KR20190000457A - Positive electrode active material for nonaqueous electrolyte secondary battery, method for producing the same, and nonaqueous electrolyte secondary battery - Google Patents

Abstract

An objective of the present invention is to provide a positive electrode active material for a nonaqueous electrolyte secondary battery which obtains high capacity and high output, and suppresses tungsten use. The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery includes mixing first lithium nickel composite oxide particles containing lithium tungstate and second lithium nickel composite oxide particles which do not contain lithium tungstate. The first lithium nickel composite oxide particles have a composition represented by Li_z1Ni_(1-x1-y1Co_x1)M^1_y1O_2, and include: a core material containing secondary particles wherein a plurality of primary particles are aggregated; and the lithium tungstate existing on at least a portion of a surface of the primary particles on a surface of and inside the first lithium nickel composite oxide particles. The second lithium nickel composite oxide particles have a composition represented by Li_z2Ni_(1-x2-y2Co_x2)M^2_y2O_2, and include secondary particles wherein a plurality of primary particles are aggregated.

Description

TECHNICAL FIELD [0001] The present invention relates to a positive electrode active material for a non-aqueous electrolyte secondary battery, a method for preparing the same, and a non-aqueous electrolyte secondary battery,

The present invention relates to a positive electrode active material for a nonaqueous electrolyte secondary battery, a method for producing the same, and a nonaqueous electrolyte secondary battery.

BACKGROUND ART In recent years, with the spread of portable electronic devices such as cellular phones and notebook computers, development of a small and lightweight secondary battery having a high energy density has been strongly desired. In addition, development of a high-output secondary battery as a battery for an electric vehicle including a hybrid vehicle is strongly desired.

As a secondary battery satisfying such a demand, there is a non-aqueous electrolyte secondary battery represented by a lithium ion secondary battery. This lithium ion secondary battery is composed of a negative electrode, a positive electrode and an electrolyte, and a material capable of separating and inserting lithium into the active material of the negative electrode and the positive electrode is used.

Such a non-aqueous electrolyte secondary battery is being actively studied and developed at present. Among them, a lithium ion secondary battery using a layered or spinel type lithium-nickel composite oxide as a positive electrode material has a high voltage of 4V , A battery having a high energy density has been put to practical use.

As materials that are mainly proposed so far, the synthesis is relatively easy to lithium cobalt oxide (LiCoO ₂₎ or lithium nickel composite oxide with low nickel than cobalt (LiNiO _2), lithium nickel cobalt manganese composite oxide (LiNi _1/3 and the like _{Co 1/3 Mn 1/3} O 2), lithium-manganese composite oxide with a manganese (LiMn ₂ O _4). Among them, the lithium-nickel composite oxide is attracting attention as a material having good cycle characteristics, low resistance and high output, and in recent years, low resistance required for high output has been emphasized.

As a method for achieving the above resistance reduction, the addition of the different element is used, and it is said that a transition metal capable of taking a high valence such as W, Mo, Nb, Ta, Re and the like is particularly useful. For example, Patent Document 1 discloses a lithium secondary battery positive electrode material in which at least one element selected from Mo, W, Nb, Ta and Re is contained in an amount of 0.1 to 5 mol% relative to the total molar amount of Mn, Ni and Co A lithium transition metal-based compound powder has been proposed. The total atomic ratio of Mo, W, Nb, Ta and Re with respect to the sum of Li of the surface portion of the primary particles and metal elements other than Mo, W, Nb, Ta and Re, And more preferably 5 times or more of According to this proposal, the lithium transition metal compound powder for the lithium secondary battery positive electrode material can be both reduced in cost and safety, and both the high load property and the powder handling property can be improved.

However, the lithium transition metal-based compound powder is obtained by pulverizing a raw material in a liquid medium, spray-drying the slurry in which the raw material is uniformly dispersed, and firing the obtained dried powder. As a result, some of these elements such as Mo, W, Nb, Ta, and Re are substituted with Ni arranged in a layered manner, and battery characteristics such as capacity and cycle characteristics of the battery are deteriorated.

Patent Document 2 discloses a positive electrode active material for a nonaqueous electrolyte secondary battery having a lithium-transition metal composite oxide having at least a layered structure, and the lithium-transition metal composite oxide is in the form of particles containing one or both of primary particles and secondary particles And at least a surface of the particles has at least one compound selected from the group consisting of molybdenum, vanadium, tungsten, boron and fluorine on the surface of the positive electrode active material for a nonaqueous electrolyte secondary battery. According to this proposal, a positive electrode active material for a non-aqueous electrolyte secondary battery having excellent cell characteristics can be obtained even under a more severe use environment. Particularly, the surface of the particles is coated with at least one By having the compound having the species, the initial characteristics are improved without impairing the improvement of the thermal stability, the load characteristics, and the output characteristics.

However, the effect of at least one kind of additive element selected from the group consisting of molybdenum, vanadium, tungsten, boron and fluorine lies in the improvement of the initial characteristics, that is, the initial discharge capacity and the initial efficiency, Not to mention. In addition, according to the production method disclosed in Patent Document 2, since the additive element is mixed with the hydroxide which is heat-treated at the same time as the lithium compound and is baked, part of the additive element is replaced with nickel arranged in layers, . ≪ / RTI >

Patent Document 3 discloses that a metal containing at least one selected from Ti, Al, Sn, Bi, Cu, Si, Ga, W, Zr, B and Mo and / And / or an oxide is coated on the positive electrode active material. With such a coating, safety can be secured by absorbing oxygen gas, but no output characteristics have been disclosed at all. In addition, the disclosed production method is to coat with an oil-based ball mill. In such a coating method, physical damage is given to the positive electrode active material, and battery characteristics are deteriorated.

Patent Document 4 proposes a positive electrode active material in which a tungstic acid compound is attached to a composite oxide particle mainly composed of lithium nickel oxide and subjected to heat treatment, and the content of carbonate ions is 0.15 wt% or less. According to this proposal, since the decomposition product of the tungstic acid compound or the tungstic acid compound is present on the surface of the positive electrode active material and the oxidation activity of the surface of the composite oxide particle in the charged state is suppressed, generation of gas by decomposition of the non- However, the output characteristics are not disclosed at all.

In addition, the production method disclosed in Patent Document 4 is preferably a method in which a sulfuric acid compound, a nitric acid compound, a boric acid compound or a phosphoric acid compound together with a tungstic acid compound is added to a composite oxide particle heated to a boiling point or higher of a solution in which the adhered component is dissolved Since the solvent is removed in a short time, there is a problem that the tungsten compound is not sufficiently dispersed on the surface of the composite oxide particle and is not uniformly deposited.

In addition, improvement in high output of the lithium-nickel composite oxide is also being carried out. For example, Patent Document 5 discloses a lithium-nickel composite oxide including secondary particles composed of primary particles and primary particles aggregated therein, and Li ₂ WO ₄ , Li ₄ WO ₅ , and Li ₆ W ₂ O ₉ , a positive electrode active material for a non-aqueous liquid electrolyte secondary battery having fine particles containing lithium tungstate is proposed, and a high output can be obtained with a high capacity.

Japanese Patent Application Laid-Open No. 2009-289726 Japanese Patent Application Laid-Open No. 2005-251716 Japanese Patent Laid-Open No. 11-16566 Japanese Patent Application Laid-Open No. 2010-40383 Japanese Patent Application Laid-Open No. 2013-171785

In Patent Document 5, although the high capacity is maintained while the high capacity is maintained, a higher capacity of a single layer is required. Further, since tungsten is a rare element and expensive, it is necessary to reduce the amount of tungsten used. Further, since tungsten is added in the middle of the manufacturing process, since the production line is contaminated with tungsten after the addition of the tungsten compound, it is necessary to perform line cleaning in the case of producing various types of products, It can be considered as an assignment.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a positive electrode active material for a non-aqueous electrolyte secondary battery in which a high output is obtained in combination with a high capacity when the negative electrode active material is used in a non-aqueous electrolyte secondary battery, and the use amount of tungsten is suppressed . It is another object of the present invention to provide a method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery that is easy to manufacture, has high productivity, and is suitable for production of various types of products.

In the first aspect of the present invention, a method for producing a positive electrode active material for a non-aqueous liquid electrolyte secondary battery includes the steps of mixing a first lithium-nickel composite oxide particle containing lithium tungstate and a second lithium-nickel composite oxide particle not containing lithium tungstate provided that the mixture, and the first lithium nickel complex oxide particles, a composition of _{Li z1 Ni 1 -x1- y1 Co x1} M 1 y1 O 2 ( However, 0≤x1≤0.35, 0≤y1≤0.35, 0.95≤z1 ≤1.15, M ¹ is a core and comprising a secondary particle which is represented by at least one element), a plurality of primary particles agglomerated with each other is selected from Mn, V, Mg, Mo, Nb, Ti and Al the 2 composite oxide particle, and the second lithium-nickel composite oxide particle is composed of lithium tungstate existing on at least a part of the surface of the primary particle located on the surface and in the interior of the composite oxide particle, and the second lithium-nickel composite oxide particle has a composition Li _z Ni _{1 -x 2- y 2} Co _{x 2} M _{² y2} O ² (However, 0≤x2≤0.35, 0≤y2≤0.35, 0.95≤z2≤1.15, M 2 is from Mn, V, Mg, Mo, Nb, Ti and Al And at least one selected element), and the plurality of primary particles are composed of secondary particles aggregated with each other.

Further, the second lithium-nickel composite oxide particles may be washed with water before mixing. The slurry concentration at the time of washing may be 500 g / L or more and 2500 g / L or less. The amount of lithium contained in the lithium compound other than lithium tungstate existing on the surfaces of the primary lithium particles and the primary lithium particles located on both surfaces of the primary lithium-nickel composite oxide particle and the secondary lithium- And may be 0.05 mass% or less with respect to the total amount. The first lithium-nickel composite oxide particle and the second lithium-nickel composite oxide particle may be mixed so that the content of the first lithium-nickel composite oxide contained in the positive electrode active material is 10 mass% or more with respect to the total amount of the positive electrode active material. The amount of tungsten contained in the first lithium-nickel composite oxide particle is preferably 0.03 atom% or more and 2.5 atom% or less with respect to the total number of atoms of Ni, Co, and M contained in the positive electrode active material. And mixing the oxide particles and the second lithium nickel composite oxide particles.

In addition, before mixing, the composition of Li ₁ Ni _{z3 -x3-} Co _{x3 y3 y3} M ¹ O ₂ (However, 0.03≤x3≤0.35, 0.01≤y3≤0.35, 0.95≤z3≤1.20, M 1 is Mn, V, At least one element selected from Mg, Mo, Nb, Ti, and Al), a base material containing secondary particles composed of a plurality of primary particles formed by aggregation, a water content of at least 2 mass% Preparing a tungsten mixture containing a compound or a lithium compound not containing a tungsten compound and tungsten; and heat treating the obtained tungsten mixture to form lithium tungstate on the surface of the primary material and on the surface of the primary particles, And the molar ratio of the total amount of lithium contained in the water, the tungsten compound, and the lithium compound to the total amount of tungsten contained in the tungsten mixture may be 5 or less. The amount of the lithium contained in the lithium compound other than lithium tungstate present on the surface and the surface of the primary particles of the first lithium-nickel composite oxide particle is preferably not more than 0.05 mass% with respect to the first lithium-nickel composite oxide particle It may be. Further, before the heat treatment, the base material and water may be mixed to form a slurry, washing the base material with water, and solid-liquid separation of the washed base material. The concentration of the water-washing slurry of the base material may be 500 g / L or more and 2500 g / L or less. When the washed base material is subjected to solid-liquid separation, the moisture content of the obtained washing cake may be controlled to 3.0% by mass or more and 15.0% by mass or less. The tungsten compound may include at least one of tungsten oxide (WO ₃ ), tungstic acid (WO ₃ .H ₂ O), Li ₂ WO ₄ , Li ₄ WO ₅ and Li ₆ W ₂ O ₉ . The temperature of the heat treatment in the heat treatment may be 100 deg. C or higher and 600 deg. C or lower. The amount of tungsten contained in the tungsten compound may be 0.05 to 3.0 atomic% with respect to the total number of atoms of Ni, Co and M contained in the base material.

In the second aspect of the present invention, the positive electrode active material for a non-aqueous liquid electrolyte secondary battery comprises a first lithium-nickel composite oxide particle containing lithium tungstate and a second lithium-nickel composite oxide particle not containing lithium tungstate, The first lithium-nickel composite oxide particle has a composition of Li _z Ni _{1 -x1- y1} Co _x1 M ¹ _y1 O ₂ (provided that 0? X? ^1? 0.35, 0? Y1? 0.35, 0.95? Z1? And at least one kind of element selected from the group consisting of Mn, V, Mg, Mo, Nb, Ti and Al), and a core material comprising a plurality of primary particles, and is composed of lithium tungstate present in at least a portion of the surface of the primary particles which is located therein, the second lithium nickel complex oxide particles, a composition of (Ni _{1 -x2- y2 z2} stage Li _x2 M ² _y2 O ₂ Co , 0≤x2≤0.35, 0≤y2≤0.35, 0.95≤z2≤1.15, M 2 is at least one kind of element selected from Mn, V, Mg, Mo, Nb, Ti and Al ), And a plurality of primary particles are composed of secondary particles aggregated with each other.

The amount of lithium contained in the lithium compound other than lithium tungstate existing on the surface of the first lithium-nickel composite oxide particle and the second lithium-nickel composite oxide particle and on the surface of the primary particle located inside the lithium- By mass or less with respect to the total amount of water. The amount of the first lithium-nickel composite oxide particles contained in the positive electrode active material may be 10 mass% or more with respect to the total amount of the positive electrode active material. The amount of tungsten contained in the lithium tungstate may be 0.03 atomic% or more and 2.5 atomic% or less with respect to the total number of atoms of Ni, Co, and M contained in the positive electrode active material. The amount of tungsten contained in lithium tungstate may be 0.05 atomic% or more and 3.0 atomic% or less based on the total number of atoms of Ni, Co, and M contained in the tungsten-coated composite oxide particles. Lithium tungstate may also be present on the surface of the first lithium-nickel composite oxide particle as a fine particle having a particle diameter of 1 nm or more and 500 nm or less and on the surface of primary particles inside. Lithium tungstate may also be present on the surface of the first lithium-nickel composite oxide particle and on the surface of the primary particles in the film as a film having a thickness of 1 nm to 200 nm. Lithium tungstate is present on the surface of the first lithium-nickel composite oxide particle and on the surface of the primary particles in the form of both the fine particles having a particle diameter of 1 nm to 500 nm and the coating film having a thickness of 1 nm to 200 nm You can.

In the third aspect of the present invention, the non-aqueous electrolyte secondary battery has a positive electrode including a positive electrode active material for a non-aqueous electrolyte secondary battery.

According to the present invention, when used for a positive electrode material of a secondary battery, a positive electrode active material for a non-aqueous electrolyte secondary battery in which a high output is obtained together with a high capacity and in which tungsten consumption is suppressed is obtained. In addition, its production method is easy, high in productivity, suitable for production on an industrial scale, and its industrial value is very large.

Fig. 1 is a schematic view (A) showing an example of a positive electrode active material according to an embodiment, and Fig. 1 (B) showing an example of a manufacturing method thereof.
2 is a schematic view showing an example of the first lithium nickel composite oxide.
3 is a cross-sectional SEM photograph (observation magnification: 10000 times) showing an example of the first lithium-nickel composite oxide (the circle surrounds lithium tungstate).
4 is a diagram showing an example of a method for producing the first lithium-nickel composite oxide.
5 is a view showing an example of a method for producing a tungsten mixture.
6 is a schematic explanatory diagram of a measurement example of impedance evaluation and an equivalent circuit used in the analysis.
7 is a schematic cross-sectional view of a coin-type battery used for evaluating a battery.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, parts are emphasized or a part thereof is shown in a simplified manner in order to facilitate understanding of the respective components, and the actual structure, shape, scale, and the like may be different. Hereinafter, the present embodiment will be described.

1. Positive electrode active material for non-aqueous electrolyte secondary battery and manufacturing method thereof

1 (A) is a schematic view showing an example of a positive electrode active material 10 for a non-aqueous liquid electrolyte secondary battery according to the present embodiment (hereinafter, simply referred to as "positive electrode active material"). FIG. 1 is a view showing an example of a method for producing the positive electrode active material 10 of the embodiment. Hereinafter, first, the positive electrode active material 10 will be described, and then a method for producing the positive electrode active material 10 and a nonaqueous electrolyte secondary battery using the positive electrode active material 10 (hereinafter simply referred to as " secondary battery " .

(1) Positive electrode active material for non-aqueous electrolyte secondary battery

1 (A), the positive electrode active material 10 is composed of a first lithium-nickel composite oxide particle (hereinafter sometimes referred to as "first complex oxide particle") 1 containing lithium tungstate and a second lithium- , And second lithium-nickel composite oxide particles 2 (hereinafter sometimes referred to as " second composite oxide particles ") not containing lithium tungstate.

The first composite oxide particle 1 is composed of a core material 5 including secondary particles 4 in which a plurality of primary particles 3 are aggregated with each other and a core material 5 including a surface of the first composite oxide particle 1 And lithium tungstate 6 (6a and 6b) present in at least a part of the surface of the primary particles 3 (3a and 3b) located therein. The first complex oxide particle 1 has lithium tungstate 6 on the surface of the primary particles 3 to obtain a high output when the positive electrode active material 10 is used in a secondary battery, (Hereinafter sometimes referred to as " battery capacity ") can be improved.

Generally, when the surface of a lithium-nickel composite oxide particle is completely covered with a heterogeneous compound, the movement (intercalation) of lithium ions is largely limited, and consequently, the advantage that the lithium-nickel composite oxide has a high capacity have.

On the other hand, the first composite oxide particle 1 used in the present embodiment has lithium tungstate (hereinafter referred to as " LWO compound ") on the surface and inside surfaces of the primary particles 3 (3a and 3b) (6). ≪ / RTI > This LWO compound (6) has high lithium ion conductivity and has an effect of accelerating the movement of lithium ions. Thus, when the positive electrode active material 10 is used in a secondary battery, the LWO compound 6 is provided on the surface of the primary particles 3 (3a and 3b) of the first composite oxide particle 1, (Hereinafter referred to as " positive electrode resistance ") can be reduced by forming a conduction path of Li at the interface between the positive and negative electrodes 3a and 3b and the electrolyte. By reducing the positive electrode resistance, the voltage lost in the battery is reduced, and the voltage actually applied to the load side is relatively high, so that a high output can be obtained. Further, as the voltage applied to the load side is increased, insertion / removal of lithium from the positive electrode is sufficiently performed, and thus the battery capacity can be improved.

In the case where only the secondary particle surface of the lithium-nickel composite oxide particle is covered with the layered material as in the prior art, since the specific surface area is lowered irrespective of the coating thickness, the coating has a high lithium ion conductivity The contact area with the electrolytic solution decreases. Further, in the case of forming a layered product only on the surface of the secondary particle, it is likely that the formation of the compound (layered product) is concentrated on the specific secondary particle surface. Therefore, the layered product as the coating has a high lithium ion conductivity, thereby improving the charge / discharge capacity and reducing the reaction resistance. However, the effect is not sufficient and there is room for improvement.

On the other hand, when the positive electrode active material 10 is used in a secondary battery, the contact between the first complex oxide particle 1 and the electrolyte occurs on the surface of the primary particles 3. Here, the surface of the primary particles 3 refers to the surface portion of the primary particles 3 to which the electrolyte can contact, and refers to the surface area of the primary particles (for example, primary particles 3a) exposed on the outer surface of the secondary particles (For example, primary particles 3b) exposed to the surface or the vicinity of the surface of the secondary particles capable of permeating the electrolyte through the outside of the secondary particles 4 and the voids therein. Further, the surface of the primary particles 3 includes, for example, intergranular particles between the primary particles in which the bonding of the primary particles is incomplete and the electrolyte solution is permeable.

When the positive electrode active material 10 is used in the secondary battery as described above, contact between the first complex oxide particle 1 and the electrolyte is prevented by not only contacting the outer surface of the secondary particles 4 formed by agglomeration of the primary particles 3, In the vicinity of the surface of the substrate and in voids inside the substrate and incomplete grain boundaries. Therefore, by further forming the LWO compound 6 on the surface of the primary particles (3) (3a, 3b), the movement of lithium ions can be further promoted. The first complex oxide particle 1 is not limited not only to the surface of the primary particle 3a located on the surface of the secondary particle 4 but also to the surface of the primary particle 3b located inside the secondary particle 4, 6), the reaction resistance of the lithium-nickel composite oxide particles can be further reduced.

Fig. 2 is a schematic view showing an example of the first composite oxide particle 1, and Fig. 3 is a cross-sectional SEM photograph (observation magnification 10,000 times) showing an example of the first complex oxide particle 1. Fig. When the LWO compound 6 contained in the first complex oxide particle 1 is present on the surface of the primary particles 3 (3a, 3b), the form thereof is not particularly limited. The LWO compound 6 can be prepared by dispersing the primary particles 3 (3a) and (3b) in the form of fine particles 6a and 6b having a particle diameter of 1 nm to 500 nm, for example, . In such a case, since the contact area with the electrolytic solution is sufficient, and lithium ion conduction can be effectively improved, the charge / discharge capacity can be improved and the positive electrode resistance can be more effectively reduced.

When the particle diameter of the LWO compound (fine particles) 6a, 6b is less than 1 nm, the fine particles 6a, 6b may not have sufficient lithium ion conductivity. When the particle diameter of the LWO compound (fine particles) 6a and 6b exceeds 500 nm, the formation of the fine particles (LWO compound 6) on the surface of the primary particles 3 (3a and 3b) And the effect of reducing the reaction resistance may not be sufficiently obtained. From the viewpoint of uniformly distributing the fine particles of the LWO compound 6 on the surfaces of the primary particles 3 (3a and 3b) and obtaining a higher effect, the particle size of the LWO compound (fine particles) 6a and 6b is preferably Is not less than 1 nm and not more than 300 nm, and more preferably not less than 5 nm and not more than 200 nm.

The LWO compound 6 is not necessarily formed on the entire surface of the primary particle surface, but may be in a state of being dotted. If LWO is formed on the surface of the primary particle exposed on the outer surface and inside of the lithium-nickel composite oxide particle, the effect of reducing the reaction resistance can be obtained even in the state where the LWO compound 6 is dotted. Not all of the LWO compounds (fine particles) 6a and 6b need to be present as fine particles having a particle diameter of 1 nm to 500 nm, and preferably LWO compounds (fine particles) 6a and 6b formed on the surfaces of the primary particles When the number is 50% or more and the particle diameter is 1 nm or more and 500 nm or less, a high effect can be obtained.

The LWO compound 6 exists in such a form that the surfaces of the primary particles 3a and 3b are coated with the thin films (coatings) 6c and 6d formed of the LWO compound, for example, as shown in FIG. 2 (B) You can. When such coatings 6c and 6d are formed, it is possible to form a conduction path of Li at the interface with the electrolyte while suppressing the decrease of the specific surface area, thereby improving the charge / discharge capacity and reducing the reaction resistance Is obtained.

In the case of covering the surfaces of the primary particles by the coatings 6c and 6d, it is preferable that they exist on the surface of the primary particles of the lithium metal composite oxide as coatings having a thickness of 1 nm to 200 nm. In order to obtain the higher effect, the film thickness is more preferably 1 nm or more and 150 nm or less, and further preferably 1 nm or more and 100 nm or less. When the thickness of the thin films 6c and 6d is less than 1 nm, the coating may not have sufficient lithium ion conductivity. On the other hand, when the film thickness of the thin films 6c and 6d exceeds 200 nm, the lithium ion conductivity is lowered and the effect of lowering the reaction resistance may not be obtained.

The coatings 6c and 6d may be formed on at least a part of the primary particles 3a and 3b and may be partially formed on the surfaces of the primary particles 3a and 3b, for example. The film thicknesses of all the coating films 6c and 6d need not be 1 nm or more and 200 nm or less. For example, when the coatings 6c and 6d having the above-mentioned film thicknesses are formed on at least a part of the surface of the primary particles, the coatings 6c and 6d have a high effect.

The LWO compound 6 may be present on the surface of the primary particles by mixing the form of the fine particles 6a and 6b and the form of the coating of the coatings 6c and 6d as shown in Fig. do. Even in this case, a high effect on the battery characteristics can be obtained.

The properties of the primary particle surfaces 3 (3a, 3b) of the first composite oxide particle 1 can be judged by observation with, for example, an electric field type scanning electron microscope or a transmission electron microscope. In the positive electrode active material for a non-aqueous liquid electrolyte secondary battery of the present invention, for example, as shown in Fig. 3, it is confirmed that lithium tungstate is formed on the surface of primary particles of the first composite oxide particle (1).

The LWO compound (6) is not limited to the one in which W and Li are in the form of lithium tungstate, and includes those containing W and Li. The LWO compound (6) is, for example, Li ₂ WO ₄ , Li ₄ WO ₅ , Li ₆ WO ₆ , Li ₂ W ₄ O ₁₃ , Li ₂ W ₂ O ₇ , Li ₆ W ₂ O ₉ , Li ₂ W ₂ O ₇ , Li ₂ W ₅ O ₁₆ , Li ₉ W ₁₉ O ₅₅ , Li ₃ W ₁₀ O ₃₀ , Li ₁₈ W ₅ O _15, or a hydrate thereof. When such lithium tungstate is lithium, the lithium ion conductivity is further increased, and the effect of reducing the reaction resistance becomes greater.

The amount of tungsten contained in the LWO compound (6) is preferably 0.05 atomic% or more and 3.0 atomic% or less with respect to the total number of atoms of Ni, Co, and M contained in the first composite oxide particle (1) , More preferably not less than 2.0 at%, and still more preferably not less than 0.08 at% and not more than 1.0 at%. When the amount of tungsten is in the above range, a higher charge / discharge capacity and output characteristics can be compatible. The amount of tungsten can be measured by IPC emission spectroscopy (ICP method).

When the amount of tungsten is less than 0.05 atomic%, the effect of improving the output characteristics may not be sufficiently obtained. On the other hand, when the amount of tungsten exceeds 3.0 atomic%, the amount of the compound to be formed becomes excessively large, so that the lithium conduction of the lithium-nickel composite oxide and the electrolytic solution is inhibited and the charge-discharge capacity may decrease.

As shown in Fig. 1 (A), the second composite oxide particles (2) is a composition of _{Li z2 Ni 1 -x2-y2 Co} x2 M 2 y2 O 2 ( However, 0≤x2≤0.35, 0≤y2 And M ² is at least one element selected from Mn, V, Mg, Mo, Nb, Ti and Al), and the plurality of primary particles (7) Particles 8, and does not contain lithium tungstate. The positive electrode active material 10 can be obtained, for example, by mixing the first composite oxide particle 1 and the second composite oxide particle 2 as shown in Fig. 1 (B). When the first composite oxide particle 1 and the second composite oxide particle 2 are mixed, when the positive electrode active material 10 is used for the positive electrode of the secondary battery, a high output can be obtained and battery capacity can be improved have.

Generally, if there are variations in the battery characteristics among the composite oxide particles constituting the positive electrode active material, a load is applied to specific particles, and the cycle characteristics are likely to be deteriorated and reaction resistance is likely to be increased. Further, it is considered that the content of the lithium-nickel composite oxide particle containing tungsten such as the first complex oxide particle (1) is decreased, which is disadvantageous for improvement of the battery characteristics.

However, the inventors of the present invention have found that, when the first composite oxide particle (1) containing an LWO compound and the composite oxide (2) containing no LWO compound are mixed, 1) (1) is used alone as a positive electrode active material, the battery characteristics such as the output characteristics and the battery capacity are neither deteriorated nor deteriorated even if they are very small, (2) the primary particles 7 have no LWO compound It is clear that the battery characteristics can be improved as compared with the case where the second complex oxide particles (2) alone are used.

The improvement in the battery characteristics can be achieved by mixing the first composite oxide particles 1. However, in order to make the effect more satisfactory, the amount of the first composite oxide particles 1 mixed in the positive electrode active material 10 The lower limit is preferably 10 mass% or more, and more preferably 20 mass% or more, with respect to the positive electrode active material (10).

On the other hand, the upper limit of the amount of the first composite oxide particles (1) is preferably 70 mass% or less, more preferably 60 mass% or less, and most preferably 50 mass% or less, Or less. When the content of the first composite oxide particle 1 in the positive electrode active material 10 is increased, the battery characteristics become closer to the case of using the first composite oxide particle 1 alone, but from the viewpoint of suppressing the use amount of tungsten, The amount of the composite oxide particles (1) is preferably as small as possible within a range in which the improvement of the battery characteristics can be obtained.

The amount of tungsten contained in the first complex oxide particle 1 (lithium tungstate) is preferably 0.03 atomic percent to 2.5 atomic percent with respect to the total number of atoms of Ni, Co, and M contained in the positive electrode active material 10, More preferably 0.05 atomic% or more and 1.5 atomic% or less, and still more preferably 0.05 atomic% or more and 1.0 atomic% or less. The amount of tungsten is an indicator of the amount of lithium tungstate 6 present in that the positive electrode active material 10 improves the battery characteristics by the lithium tungstate 6. When the amount of tungsten is within the above range, sufficient battery characteristics can be obtained when the positive electrode active material 10 is used in a battery.

In the positive electrode active material 10, the amount of lithium contained in the lithium compound other than lithium tungstate existing on the surface of the primary particles of the first composite oxide particle (1) and the second composite oxide particle (2) Is preferably 0.05 mass% or less, and more preferably 0.03 mass% or less, with respect to the total amount of the positive electrode active material 10. By limiting the amount of excess lithium to the above range, a higher charge / discharge capacity and output characteristics can be obtained and the cycle characteristics can be improved.

The lithium compound is a compound containing lithium other than lithium tungstate present on the surface of the primary particles (3, 7). Examples of the lithium compound include lithium hydroxide, lithium carbonate and the like. These lithium compounds are inferior in the conductivity of lithium and may inhibit the migration of lithium ions from the lithium nickel complex oxide material (including the first composite oxide particle 1 and the second composite oxide particle 2). The amount of lithium contained in these lithium compounds may represent the amount of excess lithium present.

By reducing the amount of excess lithium in the positive electrode active material 10, the effect of accelerating the movement of lithium ions by the lithium tungstate 6 is enhanced, and the load on the lithium-nickel composite oxide during charging and discharging is reduced to further improve the output characteristics , The cycle characteristics can be further improved. Further, by controlling the amount of excess lithium in the positive electrode active material 10 to fall within the above range, lithium ions (lithium ions) in the lithium-nickel composite oxide particles (including the first composite oxide particle 1 and the second composite oxide particle 2) And the load on the specific lithium-nickel composite oxide particle is suppressed, and the above effect can be enhanced.

The lower limit of the amount of residual lithium is not particularly limited, but is preferably 0.01% by mass or more from the viewpoint of suppressing deterioration of battery characteristics. An excessively small amount of excess lithium indicates that lithium is excessively drawn out from the crystal of the lithium-nickel composite oxide particle, and battery characteristics are liable to be deteriorated. The amount of excess lithium can be calculated by adding pure water to the positive electrode active material and stirring for a certain period of time and then analyzing the state of the lithium compound eluted from the neutralization point appearing by adding hydrochloric acid while measuring the pH of the filtered solution .

The content of the sulfate group (sulfate group) in the positive electrode active material 10 is preferably 0.05 mass% or less, more preferably 0.025 mass% or less, and still more preferably 0.020 mass% or less. When the content of the sulfate group in the positive electrode active material 10 exceeds 0.05 mass%, the negative electrode material is required to be used for the battery further as much as the irreversible capacity of the positive electrode active material in constituting the battery. As a result, The capacity per unit volume and the volume becomes small, and the extra lithium accumulated in the negative electrode as irreversible capacity is also not preferable from the viewpoint of safety. The lower limit of the sulfuric acid radical content in the positive electrode active material 10 is not particularly limited, but is, for example, 0.001 mass% or more. The sulfuric acid muscle content can be determined by converting the amount of sulfur (S) measured by IPC emission spectrochemical analysis (ICP method) into the amount of sulfuric acid radical (SO ₄ ).

The lithium amount of the entire positive electrode active material 10 (including the first complex oxide particle 1 and the second complex oxide particle 2) is preferably such that the sum (Me) of the number of atoms of Ni, Co and M in the positive electrode active material, The ratio of the number of atoms of Li (Li / Me) is preferably in the range of 0.95 or more and 1.20 or less, more preferably 0.97 or more and 1.15 or less. When the Li / Me is less than 0.95, the reaction resistance of the positive electrode in the non-aqueous electrolyte secondary battery using the obtained positive electrode active material becomes large, so that the output of the battery becomes low. If Li / Me exceeds 1.20, the initial discharge capacity of the positive electrode active material decreases and the reaction resistance of the positive electrode also increases. Li / Me can be measured by IPC emission spectroscopy (ICP method).

Lithium nickel composite oxide particle as a first core material 5 of the composite oxide particles (1) is a composition of _{Li z1 Ni 1 -x1- y1 Co x1} M 1 y1 O 2 ( However, 0≤x1≤0.35, 0≤ y1≤0.35, 0.95≤z1≤1.15, M ¹ is represented by at least one element) selected from Mn, V, Mg, Mo, Nb, Ti and Al. The Li / Me in the core material 5 is more preferably 0.95 or more and 1.15 or less, and still more preferably 0.95 or more and 1.10 or less.

The positive electrode active material 10 improves the output characteristics and the cycle characteristics by forming lithium tungstate 6a and 6b on the surfaces of the primary particles 3a and 3b of the first composite oxide particle 1. The powder characteristics such as particle diameter and tap density as the positive electrode active material may be within the range of the normally used positive electrode active material.

The effect of providing lithium tungstate on the surface of the primary particles of the lithium-nickel composite oxide particle can be achieved by using a powder such as a lithium-cobalt-based composite oxide, lithium-manganese-based composite oxide, lithium nickel- The present invention can be applied not only to the positive electrode active material of the present invention but also to the generally used positive electrode active material for a lithium secondary battery.

(2) Manufacturing method of positive electrode active material for non-aqueous electrolyte secondary battery

1 (B), the production method of the positive electrode active material 10 comprises the first lithium-nickel composite oxide particles (first complex oxide particle) 1 containing lithium tungstate (LWO compound) 6, And second lithium-nickel composite oxide particles (second composite oxide particles) (2) not containing the LWO compound (6). 4 is a diagram showing an example of a method for producing the first composite oxide particle 1. Referring to Fig. 5, when describing the method for producing the first composite oxide particle 1, as appropriate. In addition, the following description is an example of the manufacturing method, and the manufacturing method is not limited thereto.

A first complex oxide particles (1) is a composition of _{Li z1 Ni 1 -x1- y1 Co x1} M 1 y1 O 2 ( However, 0≤x1≤0.35, 0≤y1≤0.35, 0.95≤z1≤1.15, ¹ M A core material 5 represented by an element selected from the group consisting of Mn, V, Mg, Mo, Nb, Ti, and Al and containing secondary particles in which a plurality of primary particles are aggregated with each other, And an LWO compound 6 present on at least a part of the surface of the oxide particle 1 (core material) and the surface of the primary particle 3 located inside the oxide particle 1 (core material). The method for producing the first complex oxide particle (1) may be any method capable of presenting lithium tungstate on the surface thereof, and a conventionally known production method can be used. Hereinafter, an example of a method of manufacturing the first composite oxide particle 1 will be described with reference to FIGS. 4 and 5. FIG.

A first complex oxide particles (1) are prepared, as shown in Fig. 4 (A), first, a composition of Li ₁ Ni _{z3 -x3-} Co _{x3 y3 y3} M ¹ O ₂ (end of, 0.00≤x3≤0.35 , 0.00≤y3≤0.35, 0.95≤z3≤1.20, M ¹ is represented by at least one element) selected from Mn, V, Mg, Mo, Nb, Ti and Al, is configured with a plurality of primary particles are agglomerated A tungsten-coated base material (hereinafter simply referred to as " base material ") containing secondary particles and a tungsten mixture containing at least 2% by mass of water and tungsten compound in the total amount of the base material are adjusted. From the viewpoint of high capacity and high safety, it is preferable that 0.01? X3? 0.10, 0.01? Y3? 0.05, and 0.97? Z3?

The tungsten mixture contains 2% by mass or more of water with respect to the entire base material. As a result, tungsten in the tungsten compound penetrates the voids between the primary particles communicating with the outside of the secondary particles (base material) and the intergranular particles between the incomplete primary particles, and a sufficient amount of tungsten can be dispersed on the surfaces of the primary particles . The upper limit of the amount of water is not particularly limited, but is, for example, 20 mass% or less. In the case where the excessive amount of water is excessive, the heat treatment efficiency of the subsequent process is lowered, or the elution of lithium from the lithium metal composite oxide particles (base material) increases, so that the molar ratio of Li eluted in the tungsten mixture becomes excessively high, The battery characteristics when used in the positive electrode of the battery may deteriorate.

The amount of moisture with respect to the total amount of the base material is preferably 2 mass% or more and 20 mass% or less, more preferably 3 mass% or more and 15 mass% or less, further preferably 3 mass% or more and 10 mass% or less. When the amount of water is in the above range, the pH is raised by the lithium component eluted in the water, and the effect of suppressing the elution of excessive lithium is exhibited. The water content in the tungsten mixture can be easily controlled within the above range by washing the base material with water and solid-liquid separation as described later. The molar ratio of Ni, Co and M ^{1 in} the base material powder is maintained up to the first complex oxide particle 1 (core material 5).

The tungsten compound is a compound containing tungsten (W), and preferably has a water solubility such that it is soluble in the water contained in the tungsten mixture. When the tungsten compound is water-soluble, tungsten (W) can sufficiently penetrate to the primary particle surface inside the secondary particles (base material). The tungsten compound may be, for example, a solid state or an aqueous solution state. When the tungsten compound is in the form of an aqueous solution, the tungsten compound (aqueous solution) may be an amount capable of penetrating to the primary particle surface in the secondary particle (base material), and may include a solid state in a part of the aqueous solution. The tungsten compound may be a compound that dissolves in water at room temperature, or dissolves in water at the time of heat treatment. Further, in the tungsten compound, the water content in the tungsten mixture is alkaline due to the lithium contained in the base material, so that the tungsten compound may be soluble in alkalinity.

The tungsten compound is not particularly limited as long as it is a water-soluble compound, and examples thereof include tungsten oxide, tungstic acid, lithium tungstate, ammonium tungstate, and sodium tungstate. Of these, tungsten oxide, tungstic acid, lithium tungstate and ammonium tungstate are more preferable, and tungsten oxide (WO ₃ ), tungstic acid (WO ₃ .H ₂ O), tungsten More preferable is lithium lithium (Li ₂ WO ₄ , Li ₄ WO ₅ , Li ₆ W ₂ O ₉ ). The tungsten compound may be used alone or in combination of two or more.

The upper limit of the molar ratio of the water and the tungsten compound or the total amount of lithium (Li) contained in the water and the tungsten compound to the lithium compound (hereinafter referred to as " Li molar ratio ") with respect to the amount of tungsten (W) Preferably 5.0 or less, more preferably 4.5 or less, and further preferably 4.0 or less. When the upper limit of the Li molar ratio is in the above range, the excess lithium amount of the first composite oxide particle can be suppressed, the output characteristics can be improved, and the cycle characteristics can be improved.

On the other hand, the lower limit of the Li molar ratio is preferably 0.5 or more, more preferably 1.0 or more, and still more preferably 1.5 or more. Lithium calculated as a molar ratio of Li in the tungsten mixture forms tungsten (W) derived from a tungsten compound and lithium tungstate upon a subsequent heat treatment. At least a part of the lithium may be lithium derived from the base material. When the lower limit of the Li molar ratio is less than 0.5, if the Li molar ratio is less than 0.5, lithium from the base material is drawn out from the base material and lithium tungstate is formed excessively, thereby deteriorating the battery characteristics of the first composite oxide particle.

The amount of tungsten contained in the tungsten mixture is preferably 0.05 atom% or more and 3.0 atom% or less, more preferably 0.05 atom% or more and 2.0 atom% or less, relative to the total number of atoms of Ni, Co, and M contained in the base material And preferably 0.08 atom% or more and 1.0 atom% or less. When the amount of tungsten is within the above range, the amount of tungsten contained in lithium tungstate in the first composite oxide particle 1 can be set within a preferable range, and when the positive electrode active material 1 is used in a secondary battery, The capacity and the output characteristics can be made compatible at a higher level.

When adjusting the above tungsten mixture, water may be supplied and mixed with the tungsten compound so that the water content of the tungsten mixture is 2 mass% or more. Alternatively, an aqueous solution of tungsten compound or water and tungsten compound may be separately supplied.

Further, the lithium source forming the lithium tungstate is a lithium source derived from, for example, a tungsten compound such as lithium tungstate, or a lithium source derived from a base material (Li _{z 3} Ni _{1 -x 3 -y 3} Co _{x 3} M ¹ _{y 3} O ₂ or surplus lithium) And can be derived from lithium. Further, as shown in Fig. 4 (B), the tungsten mixture may contain a lithium compound not containing tungsten in addition to the base material, water, and tungsten compound. The lithium compound may be a lithium source that forms lithium tungstate. Examples of the lithium compound not containing tungsten include water-soluble compounds such as lithium hydroxide.

5 is a view showing an example of a method of adjusting a tungsten mixture obtained in the process of manufacturing the first composite oxide particle (1). As shown in Fig. 5, the lithium-nickel composite oxide particles to be the base material may be washed with water before adjusting the tungsten mixture. Washing can be performed by mixing the base material with water and slurrying. When the base material is washed with water, impurity elements such as unreacted lithium compounds and sulfuric acid radicals existing in excess to deteriorate battery characteristics can be removed. Examples of the unreacted lithium compound include lithium hydroxide and lithium carbonate.

When the base material is washed with water, the amount of lithium present in the water in the tungsten mixture is reduced, and the upper limit of the Li mole ratio can be easily controlled. In general, lithium metal complex oxides obtained by firing a metal complex hydroxide or a metal complex oxide with a lithium compound have unreacted lithium compounds on the surfaces of secondary particles and primary particles. Lithium (Li) derived from the unreacted lithium compound contained in the base material is eluted in the added water when the tungsten mixture is adjusted. When the amount of lithium eluted in the water becomes excessively large, it may be difficult to control the upper limit of the Li molar ratio within the above range.

Further, the washed base material may be subjected to solid-liquid separation after washing with water to adjust the water content. When the base material is subjected to solid-liquid separation, the amount of water contained in the tungsten mixture can be easily adjusted.

The washing condition by the slurrying of the base material is not particularly limited as long as it can sufficiently reduce the unreacted lithium compound. The amount of the unreacted lithium compound contained in the base material after washing is, for example, 0.08 mass% or less, preferably 0.05 mass% or less, with respect to the total amount of the base material. The amount of the unreacted lithium compound contained in the base material can be measured in the same manner as the amount of excess lithium in the positive electrode active material 1. [

Washing by slurrying is carried out, for example, by mixing the base material powder and water and stirring. The concentration of the base material powder contained in the slurry is, for example, from 200 g to 5000 g per 1 L of water. When the concentration of the base material powder is within this range, it is possible to sufficiently reduce the unreacted lithium compound while suppressing deterioration due to elution of lithium from the base material.

The washing time may be, for example, from 5 minutes to 60 minutes or less. When the water washing time is in this range, the amount of unreacted lithium compound contained in the base material can be reduced. The rinsing temperature may be in the range of 10 占 폚 to 40 占 폚. When the rinsing temperature is in this range, the amount of unreacted lithium compound contained in the base material can be reduced.

In the case of washing the base material, the procedure for adding the tungsten compound is not particularly limited as long as the tungsten mixture as described above is obtained. For example, as shown in Fig. 5A, after the tungsten mixture is adjusted by mixing the base material and the tungsten compound, the tungsten mixture (including the base material) may be washed with water. In this case, since the tungsten compound is washed out by washing with water, the amount of tungsten in the tungsten mixture sometimes becomes insufficient. Therefore, it is preferable to obtain a tungsten compound by adding a tungsten compound in at least one of the steps of washing the base material or the solid-liquid separation step, for example, as shown in FIGS. 5 (B) and 5 Do.

When a tungsten compound is added in a water washing step, a tungsten compound may be added to water to be mixed with a base material (powder) in advance to prepare an aqueous solution or suspension. Alternatively, a tungsten compound may be added to the slurry after mixing the base material and water to form a slurry do.

As shown in Fig. 5 (B), when a tungsten compound is added at the time of washing the base material, it is preferable to use a compound that dissolves the tungsten compound in the slurry at the time of water washing or a compound that does not contain lithium. Examples of the lithium-containing tungsten compound dissolved in the slurry include lithium tungstate (Li ₂ WO ₄ , Li ₄ WO ₅ , and Li ₆ W ₂ O ₉ ), and as the tungsten compound containing no lithium , For example, tungsten oxide (WO ₃ ) and tungstic acid (WO ₃ .H ₂ O). By using these tungsten compounds, the amount of lithium in the tungsten mixture can be easily controlled without being affected by the amount of lithium contained in the tungsten compound in the tungsten mixture.

When the tungsten compound is added after the solid-liquid separation as shown in Fig. 5 (C), there is no lithium or tungsten to be removed together with water at the time of solid-liquid separation, and the tungsten compound remains in the mixture. . In this case, the tungsten compound may be in the form of an aqueous solution or a powder.

When a tungsten compound is added during the washing process, the tungsten compound may be in the form of an aqueous solution or a powder. The tungsten compound is added to the slurry and stirred to obtain a homogeneous mixture.

When the aqueous solution or a water-soluble compound is used for the tungsten compound to be used, most of the tungsten compound dissolved in the slurry is removed together with the slurry liquid component in the solid-liquid separation step after water washing. However, the amount of tungsten in the tungsten mixture can be made sufficient by tungsten dissolved in water in the tungsten mixture. The amount of tungsten in the tungsten mixture can be stabilized with water content by washing or solid-liquid separation conditions. Therefore, these conditions can be determined in addition to the kind and amount of tungsten compound to be added by a preliminary test. The amount of water for tungsten in the tungsten mixture and the total amount of lithium contained in the tungsten compound (hereinafter referred to as the total amount of lithium) can be determined by a preliminary test like the amount of tungsten.

Further, the amount of tungsten in the mixture when the tungsten compound is added in the washing step can be determined by ICP emission spectroscopy. The amount of lithium contained in the water constituting the mixture can be determined from the analytical value of lithium and the water content by ICP emission spectroscopy in liquid components separated by solid-liquid separation after washing with water.

The amount of lithium contained in the tungsten compound of the solid component constituting the tungsten mixture is obtained by adding a tungsten compound to an aqueous lithium hydroxide solution having the same concentration as that of the liquid component after the water rinsing and stirring under the same conditions as those at the time of washing with water, The amount remaining as a solid component in the tungsten mixture is calculated from the remaining tungsten compound as a solid component.

Further, the amount of tungsten in the mixture when the tungsten compound is added after the solid-liquid separation step can be obtained from the amount of the tungsten compound to be added.

On the other hand, the total amount of lithium in the tungsten mixture is determined by the amount of lithium in the water determined from the analytical value and water content of lithium in the liquid component separated by solid-liquid separation after washing with water and the amount of lithium in the tungsten compound, Can be calculated as a sum.

When the tungsten compound is added as an aqueous solution after the solid-liquid separation step, it is necessary to adjust the aqueous solution so that the water content does not exceed 20 mass%, as described above, and the tungsten concentration is preferably 0.05 mol / L or more and 2 mol / L or less. When the tungsten concentration is within the above range, the amount of tungsten necessary can be added while suppressing the moisture content of the tungsten mixture. When the water content exceeds 20 mass%, it is necessary to adjust the water content again by solid-liquid separation, but it is necessary to determine the amount of tungsten and the amount of lithium in the removed liquid component to confirm the Li molar ratio of the mixture.

In order to make the water content included in the tungsten mixture 2 mass% or more, mixing after solid-liquid separation is preferably performed at a temperature of 50 캜 or lower. If the temperature is higher than 50 占 폚, the moisture content may be less than 2 mass% by drying during mixing.

The mixing with the tungsten compound is not limited as long as it is a device capable of mixing uniformly, and a general mixer can be used. For example, the lithium metal composite oxide particles may be sufficiently mixed with the tungsten compound to such an extent that the fracture of the lithium metal composite oxide particles is not destroyed by using a shaker mixer, a Reedge mixer, a Julia mixer, or a V blender.

The composition of the first complex oxide particle (1) is composed of a composite oxide particle as a base material, tungsten which is increased by addition in the adjustment process, and a lithium component which is added as required. In view of the high capacity and low reaction resistance, the base material preferably has a composition represented by the general formula Li _z Ni _{1 -x- y} Co _x M _y O ₂ (with 0 < _x ? 0.35, 0? Y? 0.35, 0.95? Z Lt; 1.20, and M is at least one element selected from Mn, V, Mg, Mo, Nb, Ti and Al).

On the other hand, in the case of washing the base material, Li / Me (equivalent to z in the general formula) in the base material is reduced by dissolving lithium in the washing with water, so the reduction amount is confirmed by a preliminary test in advance, Li / Me adjusted base material can be used. The amount of reduction of Li / Me by general water washing conditions is about 0.03 to 0.08. Further, even when a small amount of water is supplied in the mixing step, lithium is eluted. Therefore, in the case of washing with water, z representing Li / Me of the base material before washing is preferably 0.95? Z? 1.20, more preferably 0.97? Z? 1.15.

In addition, since it is advantageous in improving the output characteristics that the contact area with the electrolytic solution is increased, it is advantageous in that it is composed of secondary particles formed by agglomeration of primary particles and primary particles, It is preferable to use an oxide powder.

When mixing the base material and the tungsten compound, or the tungsten compound and the lithium compound, a general mixer can be used. For example, a shaker mixer, a loader mixer, a julia mixer, a V blender, an air blender or the like may be used to sufficiently mix the moldings of the tungsten-coated base material so as not to be broken. In addition, the surplus Li contained in the base material adsorbs carbon dioxide to form lithium carbonate, which causes gas generation. Therefore, it is preferable that the mixed atmosphere is performed at a carbon dioxide concentration of 0 to 100 ppm.

Then, as shown in Fig. 4, the tungsten mixture thus obtained is heat-treated. By the heat treatment, lithium contained in the water of the tungsten mixture reacts with tungsten, and lithium tungstate (LWO compound) is formed on the surface of the primary particles of the base material (core material) to obtain the first composite oxide particle (1) .

The heat treatment conditions are not particularly limited as long as the LWO compound 6 is formed on the surface of the primary particles of the base material (core material). The heat treatment conditions are, for example, in order to prevent deterioration of the electrical characteristics when the positive electrode active material 10 is used in the secondary battery, avoid reaction with moisture or carbonic acid in the atmosphere, Atmosphere.

It is preferable that the heat treatment is performed at a temperature of 100 占 폚 or higher and 600 占 폚 or lower from the viewpoint of preventing deterioration of electrical characteristics when the positive electrode active material 10 is used in a secondary battery. When the heat treatment temperature is less than 100 ° C, evaporation of water is not sufficient and the LWO compound 6 may not be sufficiently formed. On the other hand, if the heat treatment temperature exceeds 600 ° C, the primary particles of the lithium metal composite oxide cause sintering, and a part of tungsten is dissolved in the layered structure of the lithium metal composite oxide, so that the charge- .

On the other hand, when the tungsten compound contained in the tungsten mixture is not dissolved in water and remains as a solid matter, and particularly when a tungsten compound is added as a powder after the solid-liquid separation step, while the solids are sufficiently dissolved, It is preferable to set the temperature raising rate to 0.8 to 1.2 캜 / minute until it exceeds 90 캜. Even in the step of adjusting the tungsten compound, the powder of the tungsten compound is dissolved in the water contained in the mixture. However, at such a temperature raising rate, the solid tungsten compound is sufficiently dissolved during the heating to penetrate the surface of the primary particles in the secondary particles . In the case of dissolving a solid tungsten compound, it is preferable that heat treatment is performed in a closed container so that moisture does not volatilize while the dissolution is sufficiently performed.

The heat treatment time is not particularly limited, but is preferably from 3 hours to 20 hours, more preferably from 5 hours to 15 hours from the viewpoint of sufficiently evaporating the water in the tungsten mixture to form the LWO compound (6) Do.

The heat treatment may be performed by a first heat treatment in which a tungsten compound is dissolved by reacting a lithium compound existing on the surface of the primary particles of the base material with a tungsten compound to perform a first heat treatment for dispersing tungsten on the surface of the primary particles, And then performing a second heat treatment for forming a lithium tungstate compound on the surface of primary particles of the lithium-nickel composite oxide particle by heat-treating at a higher temperature.

In the first heat treatment, by heating the tungsten compound containing tungsten compound, not only the lithium eluted in the mixture but also the lithium compound remaining on the surface of the primary particles of the base material reacts with the tungsten compound to dissolve. As a result, the surplus lithium in the obtained tungsten-coated composite oxide particles can be greatly reduced and battery characteristics can be improved. Further, it has an effect of drawing excess lithium present in the base material, and the drawn lithium reacts with the tungsten compound to contribute to the improvement of the crystallinity when the tungsten-coated composite oxide particles are formed, . By the first heat treatment, tungsten is sufficiently dissolved in moisture in the tungsten mixture, and penetrates into voids or incomplete grain boundaries between primary particles in the secondary particles of the base material, and tungsten can be dispersed on the surface of the primary particles.

The heat treatment temperature in the first heat treatment is preferably 60 to 80 캜. When the heat treatment temperature is within this range, the reaction proceeds sufficiently and moisture can remain until the tungsten penetrates, and the lithium compound and the tungsten compound can be reacted to sufficiently disperse the tungsten on the surface of the primary particles. When the first heat treatment temperature is less than 60 占 폚, the reaction between the lithium compound and the tungsten compound existing on the surface of the primary particles of the base material does not sufficiently take place and the required amount of lithium tungstate may not be synthesized in some cases. On the other hand, when the first heat treatment temperature is higher than 80 deg. C, evaporation of water is too rapid, so that the reaction between the lithium compound and the tungsten compound existing on the surface of the primary particles and the penetration of tungsten may not sufficiently proceed.

The heating time in the first heat treatment is not particularly limited, but is preferably 0.5 to 2 hours so that the lithium compound reacts with the tungsten compound to sufficiently penetrate the tungsten.

The second heat treatment is a heat treatment at a temperature higher than the heat treatment temperature of the first heat treatment to sufficiently evaporate moisture in the mixture to form a lithium tungstate compound on the surface of the primary particles of the lithium-nickel composite oxide particle.

The heat treatment temperature of the second heat treatment is preferably 100 ° C or more and 200 ° C or less. If the second heat treatment temperature is less than 100 占 폚, evaporation of water is not sufficient and the lithium tungstate compound may not be sufficiently formed. On the other hand, if the second heat treatment temperature is higher than 200 ° C, the lithium nickel composite oxide particles form a neck through the lithium tungstate, or the specific surface area of the lithium-nickel composite oxide particle is significantly lowered, .

The heat treatment time for the second heat treatment is not particularly limited, but is preferably 1 to 15 hours, preferably 5 to 12 hours, in order to sufficiently evaporate moisture to form a lithium tungstate compound.

The atmosphere in the heat treatment (including the first heat treatment and the second heat treatment) may be performed in a decarbonated air, an inert gas, or a vacuum atmosphere in order to avoid moisture in the atmosphere or lithium reaction of the surfaces of the carbonate and lithium- desirable.

Next, as shown in Fig. 1 (B), the positive electrode active material 10 is obtained by mixing the first composite oxide particle 1 and the second composite oxide particle 2 obtained by the above method. The method for producing the second composite oxide particle (2) is not particularly limited, and a conventionally known method for producing a lithium nickel composite oxide particle can be used.

The second complex oxide particles (2) are preferably washed with water before mixing. The washing conditions can be the same as those for washing the base material of the first composite oxide particle (1). When the second composite oxide particles are washed with water, unreacted lithium compounds such as lithium hydroxide and lithium carbonate which deteriorate the battery characteristics, sulfuric acid radicals and other impurity elements can be removed.

The mixing ratio of the first composite oxide particle 1 and the second composite oxide particle 2 is such that the amount of the first composite oxide particle 1 is 10 mass% or more with respect to the positive electrode active material 10, It is preferable to mix it with oxide particles (2). The amount of the tungsten contained in the first complex oxide particle 1 is set to 0.03 to 2.5 atomic% with respect to the total number of atoms of Ni, Co and M contained in the positive electrode active material 10 1) and the second complex oxide particles (2) are mixed. Thus, higher charging / discharging capacity and output characteristics can be achieved at the same time.

When mixing the first composite oxide particle (1) and the second composite oxide particle (2), a general mixer can be used. For example, a shaker mixer, a loader mixer, a julia mixer, a V blender, an air blender or the like may be used to sufficiently mix the moldings of the tungsten-coated base material so as not to be broken.

2. Non-aqueous electrolyte secondary battery

The non-aqueous liquid electrolyte secondary battery of the present embodiment includes a positive electrode, a negative electrode, a non-aqueous electrolyte, and the like, and is constituted by the same constituent elements as a general non-aqueous electrolyte secondary battery. The embodiments described below are merely illustrative, and the non-aqueous liquid electrolyte secondary battery of the present invention is variously modified and improved based on the knowledge of those skilled in the art based on the embodiments described herein can do. The non-aqueous electrolyte secondary battery of the present invention is not particularly limited in its use.

(a) Positive electrode

Using the positive electrode active material for the non-aqueous electrolyte secondary battery described above, the positive electrode of the non-aqueous electrolyte secondary battery is manufactured, for example, as follows.

First, a positive electrode active material powder, a conductive material and a binder are mixed, and if necessary, a solvent such as activated carbon and viscosity adjustment is added and kneaded to prepare a positive electrode composite paste.

The mixing ratio of each of the positive electrode composite paste is also an important factor for determining the performance of the non-aqueous electrolyte secondary battery. When the total mass of the solid content of the positive electrode mixture excluding the solvent is 100 parts by mass, the content of the positive electrode active material is set to 60 to 95 parts by mass and the content of the conductive material is set to 1 to 20 parts by mass , And the content of the binder is preferably 1 to 20 parts by mass.

The obtained positive electrode material mixture paste is coated on the surface of, for example, an aluminum foil current collector, dried and scattered. If necessary, a pressure may be applied by a roll press or the like in order to increase the electrode density. In this manner, a sheet-shaped positive electrode can be produced. The sheet-like positive electrode can be provided in the production of a battery by cutting or the like in an appropriate size according to the intended battery. However, the manufacturing method of the positive electrode is not limited to the example, and other methods may be used.

As the conductive agent, for example, graphite (natural graphite, artificial graphite, expanded graphite and the like), carbon black-based materials such as acetylene black and Ketjenblack (registered trademark) can be used in the production of the positive electrode.

The binder acts to connect the active material particles and includes, for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), fluorine rubber, ethylene propylene diene rubber, styrene butadiene, cellulose resin, Etc. may be used.

If necessary, a solvent for dispersing the positive electrode active material, the conductive material, and the activated carbon and dissolving the binder is added to the positive electrode material. As the solvent, specifically, an organic solvent such as N-methyl-2-pyrrolidone can be used. Activated carbon may be added to the positive electrode mixture to increase the electric double layer capacity.

(b) Negative electrode

The negative electrode is formed by mixing a negative electrode active material capable of intercalating and deintercalating metal lithium or a lithium alloy or a lithium ion and a binding agent into a paste form by adding a suitable solvent to a surface of a metal foil current collector such as copper Coated, dried, and compressed to increase the electrode density as needed.

As the negative electrode active material, for example, a powder of a carbon material such as natural graphite, artificial graphite, a sintered body of an organic compound such as a phenol resin, or a coke can be used. In this case, as the negative electrode binder, a fluorine-containing resin such as PVDF may be used in the same manner as the positive electrode, and an organic solvent such as N-methyl-2-pyrrolidone may be used as a solvent for dispersing the active material and the binder .

(c) Separator

A separator is interposed between the positive electrode and the negative electrode.

The separator separates the positive electrode and the negative electrode and holds the electrolyte. The separator is a thin film such as polyethylene or polypropylene, and a film having many minute holes can be used.

(d) Non-aqueous liquid electrolyte

The nonaqueous electrolyte solution is obtained by dissolving a lithium salt as a supporting salt in an organic solvent.

Examples of the organic solvent to be used include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and trifluoropropylene carbonate, and organic solvents such as diethyl carbonate, dimethyl carbonate, ethyl methyl Chain carbonates such as carbonates and dipropyl carbonate, ether compounds such as tetrahydrofuran, 2-methyltetrahydrofuran and dimethoxyethane, sulfur compounds such as ethylmethylsulfone and butane sultone, triethyl phosphate , Phosphorus compounds such as trioctyl, and the like, or a mixture of two or more of them may be used.

As the supporting salt, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiN (CF ₃ SO ₂ ) ₂ , and the like, and complex salts thereof can be used.

In addition, the non-aqueous liquid electrolyte may contain a radical scavenger, a surfactant, a flame retardant, and the like.

(e) Shape and composition of battery

The non-aqueous electrolyte secondary battery of the present invention composed of the positive electrode, the negative electrode, the separator, and the non-aqueous liquid electrolyte described above may have various shapes such as a cylindrical shape, a laminate shape, and the like.

The positive electrode and the negative electrode are laminated via the separator to form an electrode body. The obtained electrode body is impregnated with a non-aqueous liquid electrolyte, and the positive electrode collector and the negative electrode collector are connected to each other, And the negative electrode terminal leading to the outside are connected to each other by using an collecting lead or the like and sealed in the battery case to complete the non-aqueous electrolyte secondary battery.

(f) Characteristic

The nonaqueous electrolyte secondary battery using the positive electrode active material of the present invention is high capacity and high output.

In particular, the nonaqueous electrolyte secondary battery using the positive electrode active material according to the present invention obtained in a more preferable form has a high initial discharge capacity of 165 mAh / g or more and a low positive electrode resistance when used for a positive electrode of a 2032 coin battery And is of higher capacity and higher output. In addition, it can be said that the thermal stability is high and the safety is also excellent.

A method of measuring the positive electrode resistance in the present invention is as follows.

When the frequency dependency of the battery reaction is measured by a general AC impedance method as an electrochemical evaluation method, a Nyquist line based on the solution resistance, the negative electrode resistance and the negative electrode capacity, and the positive electrode resistance and the positive electrode capacity are obtained as shown in FIG. 6 .

The battery reaction in the electrode includes a resistance component accompanied by charge transfer and a capacitance component by the electric double layer. When represented by an electric circuit, it becomes a parallel circuit of resistance and capacitance. It is expressed as an equivalent circuit in which the circuits are connected in series.

Fitting calculations are performed for the Nyquist curve measured using this equivalent circuit, and the resistance components and the capacitance components can be estimated.

The positive electrode resistance is equivalent to the diameter of the semicircle on the low frequency side of the obtained Nyquist line. From the above, it is possible to estimate the positive electrode resistance by performing AC impedance measurement on the produced positive electrode and fitting calculation on the obtained Nyquist curve by an equivalent circuit.

[Example]

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples at all.

The performance (initial discharge capacity, positive electrode resistance, cycle characteristics) of the secondary battery having the positive electrode using the positive electrode active material obtained by the present invention was measured.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is by no means limited to these Examples.

(Preparation and Evaluation of Battery)

For the evaluation of the positive electrode active material, a 2032 type coin battery (CBA) shown in Fig. 7 (hereinafter referred to as coin type battery) was used. As shown in Fig. 7, the coin-type battery (CBA) comprises an electrode EL and a case CA for housing the electrode EL therein. The electrode EL includes a positive electrode PE, a separator SE1 and a negative electrode NE and is stacked in this order so that the positive electrode PE is in contact with the inner surface of the positive electrode can PC, (NE) is held in the case (CA) so as to contact the inner surface of the negative electrode can (NC).

The case CA has a positive electrode can PC which is hollow and one end is opened and a negative electrode can NC which is disposed in the opening of the positive electrode can PC. , A space for accommodating the electrode EL is formed between the negative electrode can NC and the positive electrode can PC. The case CA is provided with a gasket GA and relative movement is fixed by the gasket GA so that the positive electrode can PC and the negative electrode can NC maintain a noncontact state. The gasket GA also has a function of sealing the gap between the positive electrode can PC and the negative electrode can NC to hermetically seal the gap between the inside of the case CA and the outside.

A coin-type battery (CBA) was produced as follows.

First, 52.5 mg of a positive electrode active material for a non-aqueous liquid electrolyte secondary battery, 15 mg of acetylene black and 7.5 mg of polytetrafluoroethylene resin (PTFE) were mixed and press-molded to a diameter of 11 mm and a thickness of 100 m at a pressure of 100 MPa, PE). The prepared positive electrode (PE) was dried in a vacuum dryer at 120 占 폚 for 12 hours. Using this positive electrode PE, the negative electrode NE, the separator SE1 and the electrolytic solution, a coin cell (CBA) was fabricated in a glove box in an Ar atmosphere controlled at -80 占 폚.

Graphite powder having an average particle diameter of about 20 mu m punched out in a circular disk having a diameter of 14 mm and an anode sheet coated with polyvinylidene fluoride on a copper foil were used for the anode NE. As the separator SE1, a polyethylene porous film having a thickness of 25 mu m was used. As an electrolytic solution, a mixture of an equal amount of ethylene carbonate (EC) and diethyl carbonate (DEC) (made by Tomiyama Kakin Kogyo K.K.) containing 1 M of LiClO ₄ as a supporting electrolyte was used.

The initial discharge capacity and the positive electrode resistance, which indicate the performance of the prepared coin-type battery (CBA), were evaluated as follows. The initial discharge capacity was set to about 24 hours after the coin type battery (CBA) was fabricated. After the open circuit voltage OCV (Open Circuit Voltage) was stabilized, the current density to the positive electrode was set to 0.1 mA / And the discharge capacity was 3.0 V after a rest of 1 hour and the cutoff voltage was 3.0 V. The initial discharge capacity was defined as the capacity.

The positive electrode resistance was measured by an AC impedance method using a frequency response analyzer and a Potenshogalvanostat (Solatron, 1255B) charged with a coin cell (CBA) at a charging potential of 4.1 V, A quiz plot is obtained. Since this Nyquist plot is shown as the sum of the solution resistance, the negative electrode resistance and its capacity, and the characteristic curve representing the positive electrode resistance and capacity thereof, fitting calculation is performed using an equivalent circuit based on this Nyquist plot, And the resistance value was calculated. Also, the positive electrode resistance was calculated by setting the relative value of Comparative Example 1 to "1.00".

In addition, in this example, each sample of the reagent grade of Wako Junyaku Kogyo Co., Ltd. was used for the preparation of the complex hydroxide, the positive electrode active material and the secondary battery.

(Example 1)

[Production of positive electrode active material]

(Preparation of First Composite Oxide Particle)

Li _{1 & lt ; / RTI & gt ;} obtained by a known technique in which an oxide containing Ni as a main component and lithium hydroxide are mixed and fired _{. 020} Ni _{0 . 91} Co _{0 . 06} Al _{0 . 03} O &lt; _{2 &} gt ;. 500 g of pure water at 25 캜 was added to 500 g of the base material to prepare a slurry, which was then stirred for 15 minutes and washed with water. The slurry after washing with water was filtered using a vacuum, and solid-liquid separation was carried out. The moisture content of the obtained cleansing cake was 8.5% by mass.

3.58 g of tungsten oxide (WO ₃ ) was added to the washing cake so that the amount of W was 0.30 at% with respect to the total number of atoms of Ni, Co and Al contained in the base material, and the mixture was transferred to a shaker mixer apparatus (Wylabakopen (WAB) Tungsten TURBULA Type T2C) to obtain a tungsten mixture.

The obtained tungsten mixture was put into an aluminum bag, and after purging with nitrogen gas, it was laminated and placed in a dryer heated to 80 DEG C for about 1 hour. After warming, it was taken out from the aluminum bag, transferred to a container made of SUS, allowed to stand for 10 hours in a vacuum drier heated to 190 DEG C, and then subjected to heat treatment.

The obtained dried tungsten mixture was sifted into a sieve having an eye size of 38 mu m to obtain lithium nickel composite oxide particles (first composite oxide particles) having a lithium tungstate compound on the surface of the primary particles of the core material (base material). It was confirmed that the obtained first composite oxide particle had a residual lithium amount (amount of Li contained in the lithium compound other than lithium tungstate) of 0.05 mass% or less.

(Production of second composite oxide particles)

Li _{1 & lt ; / RTI & gt ;} obtained by a known technique in which an oxide containing Ni as a main component and lithium hydroxide are mixed and fired _{. 020} Ni _{0 . 91} Co _{0 . 06} Al _{0 .} To 600 g of the powder of the lithium nickel complex oxide represented by ₀₃ O ₂ , 667 mL of pure water at 25 캜 was added to prepare a slurry, which was then washed with water for 15 minutes, separated by solid-liquid separation and dried to obtain second composite oxide particles. It was confirmed that the amount of residual lithium in the obtained second composite oxide particle was 0.05% by mass or less.

(Mixing of the first composite oxide particle and the second composite oxide particle)

300 g of a lithium nickel composite oxide (second composite oxide particle) not containing a lithium tungstate compound was added to 300 g of the obtained lithium-nickel composite oxide particle (first complex oxide particle), followed by stirring in a shaker mixer apparatus (WAB) Ltd., manufactured by Wako Pure Chemical Industries, Ltd.) to obtain a positive electrode active material. The tungsten content of the obtained positive electrode active material was analyzed by the ICP method, and it was confirmed that the tungsten content was 0.15 atomic% with respect to the total number of atoms of Ni, Co and Al. It was also confirmed that the sulfurous acid root content of the obtained positive electrode active material was 0.05 mass% or less.

[Surplus Lithium Analysis]

The excess lithium in the obtained positive electrode active material was evaluated by titrating Li eluted from the positive electrode active material. To 1 g of the obtained positive electrode active material, 10 ml of pure water was added and stirred for 1 minute. While the pH of the filtered solution was measured, hydrochloric acid was added to the resulting filtrate, and the state of the lithium compound eluted from the neutralization point appeared. The amount of surplus lithium was 0.02 mass% with respect to the total amount of the positive electrode active material.

[Evaluation of Battery]

The battery characteristics of the coin type battery (CBA) having the positive electrode prepared using the obtained positive electrode active material were evaluated. The positive electrode resistance was a relative value obtained by setting "1.00" as Comparative Example 1 as the evaluation value. The initial discharge capacity was 213.1 mAh / g.

The following examples and comparative examples show only the materials and conditions that are changed in Comparative Example 1. Table 1 and Table 2 together show the initial discharge capacity and the evaluation value of the positive electrode resistance of the examples and the comparative examples.

(Example 2)

Except that 5.37 g of tungsten oxide (WO ₃ ) was added to the cleaning cake such that the amount of W was 0.45 at% with respect to the total number of atoms of Ni, Co and Al contained in the lithium-nickel composite oxide (base material) Was sufficiently mixed using a shaker mixer device (TURBULA Type T2C, manufactured by WAB) to obtain a tungsten mixture.

The obtained mixture was put into an aluminum bag, and after purging with nitrogen gas, it was laminated and placed in a dryer heated to 80 DEG C for about 1 hour. After warming, the bag was taken out from the bag made of aluminum, transferred to a container made of SUS, allowed to stand for 10 hours using a vacuum drier heated to 190 캜, and then air-cooled.

The resulting dried tungsten mixture was sifted through a sieve having an eye size of 38 mu m to obtain a lithium nickel composite oxide (first composite oxide) having a lithium tungstate compound on the surface of the primary particles of the core material (base material). 600 g of a lithium nickel composite oxide (second composite oxide particle) containing no lithium tungstate compound obtained in the same manner as in Example 1 was added to 300 g of the resultant composite oxide (first complex oxide), followed by stirring in a shaker mixer apparatus WBAB TURBULA Type T2C) to obtain a positive electrode active material.

The tungsten content of the obtained positive electrode active material was analyzed by the ICP method, and it was confirmed that the tungsten content was 0.15 atomic% with respect to the total number of atoms of Ni, Co and Al.

(Example 3)

Except that 8.98 g of tungsten oxide (WO ₃ ) was added to the cleaning cake so that the amount of W was 0.75 at% with respect to the total number of atoms of Ni, Co and Al contained in the lithium-nickel composite oxide (base material) Was sufficiently mixed using a shaker mixer device (TURBULA Type T2C, manufactured by WAB) to obtain a tungsten mixture.

The obtained tungsten mixture was put into an aluminum bag, and after purging with nitrogen gas, it was laminated and placed in a dryer heated to 80 DEG C for about 1 hour. After warming, the bag was taken out from the bag made of aluminum, transferred to a container made of SUS, allowed to stand for 10 hours using a vacuum drier heated to 190 캜, and then air-cooled.

The obtained dried tungsten mixture was sieved through a sieve having an eye size of 38 mu m to obtain a lithium nickel complex oxide (first complex oxide) having a lithium tungstate compound obtained in the same manner as in Example 1 on the surface of the primary particles of the core material &Lt; / RTI &gt;

1200 g of a lithium nickel composite oxide (second composite oxide particle) not containing a lithium tungstate compound was added to 300 g of the obtained complex oxide (first complex oxide), and a shaker mixer apparatus (TURBULA TypeT2C manufactured by WAB Corp.) And sufficiently mixed to obtain a positive electrode active material.

The tungsten content of the obtained positive electrode active material was analyzed by the ICP method, and it was confirmed that the tungsten content was 0.15 atomic% with respect to the total number of atoms of Ni, Co and Al.

(Example 4)

To 500 g of the base material, 667 mL of pure water at 25 DEG C was added to prepare a slurry, which was then washed with water for 15 minutes. After washing with water, the filtrate was subjected to solid-liquid separation. The moisture content of the cleaning cake was 8.5% by mass.

4.04 g of lithium tungstate (LWO: Li ₂ WO ₄ ) was added to the washing cake so that the amount of W was 0.30 at% with respect to the total number of atoms of Ni, Co and Al contained in the lithium-nickel composite oxide (base material) And sufficiently mixed using a shaker mixer device (TURBULA Type T2C, manufactured by WAB) to obtain a tungsten mixture.

The obtained tungsten mixture was put into an aluminum bag, and after purging with nitrogen gas, it was laminated and placed in a dryer heated to 80 DEG C for about 1 hour. After warming, the bag was taken out from the bag made of aluminum, transferred to a container made of SUS, allowed to stand for 10 hours using a vacuum drier heated to 190 캜, and then air-cooled.

The resulting dried tungsten mixture was sifted through a sieve having an eye size of 38 mu m to obtain a lithium nickel composite oxide (first composite oxide) having a lithium tungstate compound on the surface of the primary particles of the core material (base material).

300 g of the lithium nickel composite oxide (second composite oxide particle) containing no lithium tungstate compound obtained in the same manner as in Example 1 was added to 300 g of the obtained complex oxide (first complex oxide), and the mixture was dispersed in a shaker mixer apparatus (TURBULA TypeT2C, manufactured by WAB) to obtain a mixed positive electrode active material.

The tungsten content of the obtained positive electrode active material was analyzed by the ICP method, and it was confirmed that the tungsten content was 0.15 atomic% with respect to the total number of atoms of Ni, Co and Al.

(Example 5)

To 500 g of the base material, 667 mL of pure water at 25 DEG C was added to prepare a slurry, which was then washed with water for 15 minutes. After washing with water, the filtrate was subjected to solid-liquid separation. The moisture content of the cleaning cake was 8.5% by mass.

6.06 g of lithium tungstate (LWO: Li ₂ WO ₄ ) was added to the washing cake so that the amount of W was 0.45 at% with respect to the total number of atoms of Ni, Co and Al contained in the lithium-nickel composite oxide (base material) And sufficiently mixed using a shaker mixer device (TURBULA Type T2C, manufactured by WAB) to obtain a tungsten mixture.

The obtained tungsten mixture was put into an aluminum bag, and after purging with nitrogen gas, it was laminated and placed in a dryer heated to 80 DEG C for about 1 hour. After warming, the bag was taken out from the bag made of aluminum, transferred to a container made of SUS, allowed to stand for 10 hours using a vacuum drier heated to 190 캜, and then air-cooled.

The obtained dried tungsten mixture was sifted through a sieve having an eye size of 38 mu m to obtain a lithium nickel composite oxide having a lithium tungstate compound (first composite oxide) on the surface of the primary particles of the core material (base material).

600 g of a lithium nickel composite oxide (second composite oxide) containing no lithium tungstate compound obtained in the same manner as in Example 1 was added to 300 g of the resultant composite oxide (first complex oxide), and the mixture was dispersed in a shaker mixer apparatus (WAB ) TURBULA Type T2C) to obtain a positive electrode active material.

The tungsten content of the obtained positive electrode active material was analyzed by the ICP method, and it was confirmed that the tungsten content was 0.15 atomic% with respect to the total number of atoms of Ni, Co and Al.

(Example 6)

To 500 g of the base material, 667 mL of pure water at 25 DEG C was added to prepare a slurry, which was then washed with water for 15 minutes. After washing with water, the filtrate was subjected to solid-liquid separation. The moisture content of the cleaning cake was 8.5% by mass.

10.14 g of lithium tungstate (LWO: Li ₂ WO ₄ ) was added to the washing cake so that the amount of W was 0.75 at% with respect to the total number of atoms of Ni, Co and Al contained in the lithium-nickel composite oxide (base material) And sufficiently mixed using a shaker mixer device (TURBULA Type T2C, manufactured by WAB) to obtain a tungsten mixture.

The obtained tungsten mixture was put into an aluminum bag, and after purging with nitrogen gas, it was laminated and placed in a dryer heated to 80 DEG C for about 1 hour. After warming, the bag was taken out from the bag made of aluminum, transferred to a container made of SUS, allowed to stand for 10 hours using a vacuum drier heated to 190 캜, and then air-cooled.

The obtained dried tungsten mixture was sifted through a sieve having an eye size of 38 mu m to obtain a lithium nickel composite oxide having a lithium tungstate compound (first composite oxide) on the surface of the primary particles of the core material (base material).

1200 g of a lithium nickel composite oxide (second composite oxide) containing no lithium tungstate compound obtained in the same manner as in Example 1 was added to 300 g of the resultant composite oxide (first complex oxide), followed by stirring in a shaker mixer apparatus (WAB ) TURBULA Type T2C) to obtain a mixed positive electrode active material.

The tungsten content of the obtained positive electrode active material was analyzed by the ICP method, and it was confirmed that the tungsten content was 0.15 atomic% with respect to the total number of atoms of Ni, Co and Al.

(Comparative Example 1)

500 g of pure water at 25 DEG C was added to 500 m &lt; 2 &gt; of a lithium nickel composite oxide particle having the same composition as that of the above-mentioned base material to obtain a slurry, and a tungsten compound was not added to the cleansing cake after solid- The composite oxide particles (corresponding to the second composite oxide) were obtained in the same manner as the oxide, and used as the positive electrode active material.

(Comparative Example 2)

The slurry was prepared by adding 667 mL of pure water at 25 DEG C to a lithium nickel composite oxide particle having the same composition as that of 500 g of the base material and that a slurry was prepared by adding pure water at 25 DEG C and that the tungsten compound was not added to the washing cake after the solid- , Composite oxide particles (corresponding to the second composite oxide) were obtained and used as the positive electrode active material.

(Comparative Example 3)

Except that 667 mL of pure water at 25 DEG C was added to 500 g of the base material to prepare a slurry, and the tungsten compound was not added to the washing cake after the solid-liquid separation, thereby obtaining a composite oxide particle Complex oxide) was obtained. 2.0 g of lithium tungstate (LWO: Li ₂ WO ₄ ) powder was added to the resulting composite oxide particle (corresponding to the second composite oxide), and the mixture was dispersed by using a shaker mixer apparatus (TURBULA TypeT2C, manufactured by WAB) And sufficiently mixed to obtain a positive electrode active material.

The tungsten content of the obtained positive electrode active material was analyzed by the ICP method, and it was confirmed that the tungsten content was 0.15 atomic% with respect to the total number of atoms of Ni, Co and Al.

[evaluation]

As is clear from Tables 1 and 2, the positive electrode active material of the examples was produced in accordance with the present invention, so that the initial discharge capacity was high and the positive electrode resistance was low, and the battery characteristics were superior to those of Comparative Examples 1 and 2 . 3 shows an example of the result of observation of the cross-sectional SEM of the positive electrode active material obtained in the example of the present invention. However, the obtained positive electrode active material contains secondary particles composed of primary particles and primary particles aggregated, and tungstic acid It was confirmed that lithium was formed. The fine particles including lithium tungstate are shown surrounded by a circle in Fig.

On the other hand, in Comparative Example 1 and Comparative Example 2, since the fine particles containing lithium tungstate were not formed on the surfaces of the primary particles, the positive electrode resistance was remarkably high and it was difficult to meet the demand for high output. In Comparative Example 3, although the resistance reduction effect was obtained by adding lithium tungstate, since the lithium tungstate compound was not formed on the surface of the primary particles of the lithium-nickel composite oxide, the battery had a low initial discharge capacity.

The non-aqueous liquid electrolyte secondary battery using the positive electrode active material of the present invention is suitably used for a power source of a small portable electronic device (notebook-type personal computer, mobile phone terminal, etc.) Can be used. Further, the non-aqueous electrolyte secondary battery of the present invention can be suitably used as a power source for an electric vehicle, which is restricted by the space for mounting, because it has excellent safety, can be downsized, and can achieve high output. Also, the non-aqueous electrolyte secondary battery using the positive electrode active material of the present invention can be used not only as a power source for an electric vehicle driven purely by electric energy, but also as a power source for a so-called hybrid vehicle which is used in combination with a combustion engine such as a gasoline engine or a diesel engine .

1: First lithium nickel composite oxide
2: Second lithium nickel composite oxide
3, 3a and 3b: primary particles (first lithium nickel composite oxide)
4: secondary particles (first lithium-nickel composite oxide)
5: Core material
6, 6a, 6b: Lithium tungstate
7: primary particles (second lithium-nickel composite oxide)
8: secondary particles (second lithium-nickel composite oxide)
10: positive electrode active material
CBA: Coin type battery
CA: Case
PC: positive electrode cans
NC: negative electrode can
GA: Gasket
EL: Electrode
PE: positive
NE: negative pole
SE1: Separator

Claims (23)

Comprising mixing a first lithium-nickel composite oxide particle containing lithium tungstate and a second lithium-nickel composite oxide particle not containing lithium tungstate,
The first lithium nickel complex oxide particles, a composition of _{Li z1 Ni 1 -x1- y1 Co x1} M 1 y1 O 2 ( However, 0≤x1≤0.35, 0≤y1≤0.35, 0.95≤z1≤1.15, ¹ M And at least one kind of element selected from Mn, V, Mg, Mo, Nb, Ti and Al), and a core material comprising a plurality of primary particles, And lithium tungstate existing on at least a part of the surface of the primary particle located on the surface and inside of the oxide particle,
The second lithium nickel complex oxide particles, a composition of _{Li z2 Ni 1 -x2- y2 Co x2} M 2 y2 O 2 ( However, 0≤x2≤0.35, 0≤y2≤0.35, 0.95≤z2≤1.15, M ² Is at least one element selected from the group consisting of Mn, V, Mg, Mo, Nb, Ti and Al), and the plurality of primary particles are composed of secondary particles
Wherein the positive electrode active material for a non-aqueous liquid electrolyte secondary battery is a positive electrode active material. The method of claim 1, wherein the second lithium-nickel composite oxide particles are washed with water before the mixing. The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 2, wherein the slurry concentration during the water washing is 500 g / L or more and 2500 g / L or less. 4. The lithium-nickel composite oxide particle according to any one of claims 1 to 3, wherein the first lithium-nickel composite oxide particle and the second lithium-nickel composite oxide particle are composed of tungstic acid Wherein the amount of lithium contained in the lithium compound other than lithium is 0.05 mass% or less with respect to the total amount of the positive electrode active material. The lithium secondary battery according to any one of claims 1 to 3, wherein the content of the first lithium-nickel composite oxide particles contained in the positive electrode active material is 10 mass% or more with respect to the total amount of the positive electrode active material, Wherein the composite oxide particle and the second lithium-nickel composite oxide particle are mixed with each other to form a positive electrode active material for a non-aqueous electrolyte secondary battery. The lithium-nickel composite oxide particle according to any one of claims 1 to 3, wherein the amount of tungsten contained in the first lithium-nickel composite oxide particle is 0.03 atom Wherein the first lithium-nickel composite oxide particle and the second lithium-nickel composite oxide particle are mixed so that the total amount of the lithium-nickel composite oxide particles is not less than 2.5% by atom and not more than 2.5% by atom. 4. The method according to any one of claims 1 to 3,
_Z3 composition Li ₁ Ni Co _{-x3- y3 x3 y3} M ¹ O ₂ (However, 0.00≤x3≤0.35, 0.00≤y3≤0.35, 0.95≤z3≤1.20, M 1 is Mn, V, Mg, Mo, Nb , At least one element selected from the group consisting of Ti and Al), a base material containing secondary particles composed of a plurality of primary particles aggregated,
2% by mass or more of water relative to the whole amount of the base material,
A tungsten compound, or a lithium compound not containing a tungsten compound and tungsten
To adjust the tungsten mixture,
Heat-treating the obtained tungsten mixture to form lithium tungstate on the surface of the primary material and on the surface of the primary particles in the primary material to obtain the first lithium-nickel composite oxide particle
And,
The tungsten mixture preferably has a molar ratio of the total amount of lithium contained in the water and the tungsten compound or the water, the tungsten compound and the lithium compound to the total amount of tungsten contained is 5 or less
Wherein the positive electrode active material for a non-aqueous liquid electrolyte secondary battery is a positive electrode active material. The lithium-nickel composite oxide particle according to claim 7, wherein the amount of lithium contained in the lithium compound other than lithium tungstate existing on the surface and the surface of the primary particles of the first lithium- By mass based on the total mass of the non-aqueous electrolyte secondary battery. The nonaqueous electrolyte secondary battery according to claim 7, further comprising a step of mixing the base material with water to form a slurry before the heat treatment, washing the base material with water, and solid-liquid separating the washed base material. A method for producing an active material. The method of manufacturing a positive electrode active material for a non-aqueous electrolyte secondary cell according to claim 9, wherein the concentration of the water-washing slurry in the base material is 500 g / L or more and 2500 g / L or less. The method for producing a positive electrode active material for a nonaqueous-electrolyte secondary battery according to claim 9, wherein when the washed base material is subjected to solid-liquid separation, the water content of the obtained washing cake is controlled to 3.0% by mass or more and 15.0% by mass or less. The method according to claim 7, wherein the tungsten compound is at least one of tungsten oxide (WO ₃ ), tungstic acid (WO ₃ .H ₂ O), Li ₂ WO ₄ , Li ₄ WO ₅ and Li ₆ W ₂ O ₉ Wherein the positive electrode active material for the non-aqueous electrolyte secondary battery is a positive electrode active material. The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 7, wherein the temperature of the heat treatment in the heat treatment is 100 占 폚 or more and 600 占 폚 or less. The nonaqueous electrolyte secondary battery according to claim 7, wherein the amount of tungsten contained in the tungsten compound is 0.05 atomic% or more and 3.0 atomic% or less relative to the total number of atoms of Ni, Co, and M contained in the base material A method for producing a positive electrode active material for a battery. A first lithium-nickel composite oxide particle containing lithium tungstate and a second lithium-nickel composite oxide particle not containing lithium tungstate,
The first lithium nickel complex oxide particles, a composition of _{Li z1 Ni 1 -x1- y1 Co x1} M 1 y1 O 2 ( However, 0≤x1≤0.35, 0≤y1≤0.35, 0.95≤z1≤1.15, ¹ M And at least one kind of element selected from Mn, V, Mg, Mo, Nb, Ti and Al), and a core material comprising a plurality of primary particles, And lithium tungstate existing on at least a part of the surface of the primary particle located on the surface and inside of the oxide particle,
The second lithium nickel complex oxide particles, a composition of _{Li z2 Ni 1 -x2- y2 Co x2} M 2 y2 O 2 ( However, 0≤x2≤0.35, 0≤y2≤0.35, 0.95≤z2≤1.15, M ² Is at least one element selected from the group consisting of Mn, V, Mg, Mo, Nb, Ti and Al), and the plurality of primary particles are composed of secondary particles
And a positive electrode active material for a non-aqueous liquid electrolyte secondary battery. The lithium secondary battery according to claim 15, wherein the amount of lithium contained in the lithium compound other than lithium tungstate existing on the surfaces of the first lithium-nickel composite oxide particles and the second lithium-nickel composite oxide particles, Is 0.05% by mass or less based on the total amount of the positive electrode active material. 16. The positive electrode active material according to claim 15, wherein the amount of the first lithium-nickel composite oxide particles contained in the positive electrode active material is at least 10 mass% with respect to the total amount of the positive electrode active material. 16. The nonaqueous electrolyte according to claim 15, wherein the amount of tungsten contained in lithium tungstate is 0.03 atom% or more and 2.5 atom% or less based on the total number of atoms of Ni, Co, and M contained in the positive electrode active material A positive electrode active material for a secondary battery. 16. The lithium-nickel composite oxide particle according to claim 15, wherein the amount of tungsten contained in lithium tungstate is 0.05 atomic% to 3.0 atomic% with respect to the total number of atoms of Ni, Co and M contained in the first lithium-nickel composite oxide particle Wherein the positive electrode active material is a positive electrode active material for a non-aqueous electrolyte secondary battery. 16. The nonaqueous electrolyte secondary battery according to claim 15, wherein the lithium tungstate is present on the surface of the first lithium-nickel composite oxide particle and on the surface of the primary particles inside the particle as fine particles having a particle diameter of 1 nm to 500 nm A positive electrode active material for a secondary battery. 16. The nonaqueous electrolyte secondary battery according to claim 15, wherein the lithium tungstate is a coating having a film thickness of 1 nm to 200 nm, which is present on the surface of the first lithium-nickel composite oxide particle and on the surface of the primary particles therein A positive electrode active material for a secondary battery. The lithium secondary battery according to claim 15, wherein the lithium tungstate is a mixture of fine particles having a particle diameter of 1 nm to 500 nm and a coating film having a thickness of 1 nm to 200 nm, Wherein the positive electrode active material is present on the surface of the primary particles. A nonaqueous electrolyte secondary battery having a positive electrode comprising the positive electrode active material for a nonaqueous electrolyte secondary battery according to any one of claims 15 to 22.

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