JP2021136206A - Manufacturing method of positive electrode active material composite for lithium ion secondary battery - Google Patents

Abstract

To provide a manufacturing method capable of easily obtaining a positive electrode active material composite for lithium ion secondary battery which is configured by sufficiently reducing a moisture content and effectively improves battery characteristics of a lithium ion secondary battery.SOLUTION: The present invention relates to a manufacturing method of a positive electrode active material composite for lithium ion secondary battery which is expressed by a specific formula on surfaces of layered lithium composite oxide secondary particles (A) consisting of lithium composite oxide particles which are expressed by a specific formula, and obtained by compositing lithium-based polyanion particles (B) carried on a surface by carbon (c) and the lithium composite oxide particles. The manufacturing method of the positive electrode active material composite for lithium ion secondary battery includes: a step (X) of blending the layered lithium composite oxide secondary particles (A) and the lithium-based polyanion particles, etc., and mixing an obtained blend slurry while adding a compressing force and a shearing force, thereby obtaining a composite slurry; and a step (Y) of drying the obtained composite slurry.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a positive electrode active material composite for a lithium ion secondary battery, which has both excellent battery characteristics and safety.

Conventionally, lithium composite oxide has been used as a positive electrode active material capable of forming a high-power and high-capacity lithium-ion secondary battery. Such a lithium composite oxide exhibits a layered crystal structure in which a lithium atom layer and a transition metal atom layer are alternately stacked via an oxygen atom layer, and one lithium atom is contained in each atom of the transition metal. It is also known to have a so-called layered rock salt structure.

In a lithium ion secondary battery using such a lithium composite oxide as a positive electrode active material, charging / discharging is performed by desorbing / inserting lithium ions into the lithium composite oxide, but usually, charging / discharging cycles are repeated. As the capacity decreases, the capacity of the battery may decrease significantly, especially after long-term use. It is considered that this is because the transition metal component of the lithium composite oxide elutes into the electrolytic solution during charging, so that the crystal structure is likely to collapse. Further, when the crystal structure of the lithium composite oxide is disintegrated, the transition metal component of the lithium composite oxide is eluted into the surrounding electrolytic solution, which may reduce the thermal stability and impair the safety.

Under these circumstances, various positive electrode active material materials have been developed in order to realize a lithium ion secondary battery having better battery characteristics. For example, Patent Document 1 states that in a Li—Ni composite oxide in which a core secondary particle has a specific composition and an average secondary particle size, a Li—Ni composite oxidation having a specific composition on the surface of the secondary particle. A Li—Ni composite oxide particle powder coated or present with a substance is disclosed, and as a method for producing such a powder, the Li—Ni composite oxide is coated by a chemical treatment by a wet method, a mechanical treatment by a dry method, or the like. Alternatively, the technology to be present is also disclosed.

Japanese Unexamined Patent Publication No. 2009-117369

However, when water is mixed in the lithium ion secondary battery, the LiPF ₆ contained in the electrolytic solution reacts with the water to generate hydrophosphate, which causes deterioration of the battery performance. Therefore, the positive activity of the lithium ion secondary battery is activated. It is necessary to reduce the water content of the substance. However, the chemical treatment by the wet method described in the above patent document may not sufficiently reduce the water content in the obtained positive electrode active material.
On the other hand, when the positive electrode active material is obtained by the dry method, the positive electrode active material easily adsorbs moisture in the atmosphere, so that mechanical treatment in a low humidity atmosphere is required. However, the mechanical treatment by the dry method described in the above patent document inevitably complicates the equipment and humidity control, and is still difficult to carry out industrially.

Therefore, the subject of the present invention is for a lithium ion secondary battery as a positive electrode active material material for a lithium ion secondary battery, in which the water content is sufficiently reduced and the battery characteristics of the lithium ion secondary battery are effectively improved. An object of the present invention is to provide a production method capable of easily obtaining a positive electrode active material composite.

Therefore, as a result of diligent studies to solve the above problems, the present inventor has conducted a simple method such as mixing a raw material compound with a specific organic solvent in a specific amount while applying compressive force and shearing force. As a result, we have found a production method capable of obtaining a positive electrode active material composite for a lithium ion secondary battery in which the water content is sufficiently reduced.

That is, the present invention has the following formula (I) or formula (II):
LiNi _a Co _b Mn _c M ¹ _x O ² ... (I)
In formula (I), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Indicates one or more elements selected from Bi and Ge. A, b, c, x are 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, Indicates a number that satisfies 0 ≦ x ≦ 0.3 and 3a + 3b + 3c + ( ^{valence of M 1} ) × x = 3).
^{_{LiNi d Co e Al f M 2}} y O 2 ··· (II)
In formula (II), M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Indicates one or more elements selected from Ge. D, e, f, y are 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ Indicates a number that satisfies y ≦ 0.3 and 3d + 3e + 3f + ( ^{valence of M 2} ) × y = 3).
On the surface of the layered lithium composite oxide secondary particles (A) composed of lithium composite oxide particles represented by, the following formula (III) or formula (IV):
LiCo _p M ³ _z PO ₄ ... (III)
(In formula (III), M ³ represents Fe, Mn, Mg, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. P and z are 0.3. <Indicates a number satisfying p ≦ 1, 0 ≦ z ≦ 0.3, and 2p + ( ^{valence of M 3} ) × z = 2.
LiFe _q Mn _r M ⁴ _v PO ₄ ... (IV)
(In formula (IV), M ⁴ represents Co, Mg, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. Q, r, and v are 0 ≦ met q ≦ 1,0 ≦ r ≦ 1,0 ≦ v ≦ 0.3, and q + r ≠ 0, and shows a number satisfying × v = 2 (valence of ^{M 4) 2q + 2r +.} )
A method for producing a positive electrode active material for a lithium ion secondary battery, which is represented by a composite of lithium-based polyanion particles (B) having carbon (c) supported on its surface and lithium composite oxide particles. , Next steps (X)-(Y):
(X) With respect to 100 parts by mass of the layered lithium composite oxide secondary particles (A), the lithium-based polyanion particles (B) having carbon (c) supported on the surface, and the lithium-based polyanion particles (B). A step of blending an organic solvent (D) having a boiling point of 50 ° C. to 150 ° C., which is 30 parts by mass to 3000 parts by mass, and mixing the obtained compounded slurry while applying compressive force and shearing force to obtain a composite slurry. (Y) Provided is a method for producing a positive electrode active material composite for a lithium ion secondary battery, which comprises a step of drying the obtained composite product slurry.

According to the production method of the present invention, a positive electrode active material composite for a lithium ion secondary battery can be simplified because the water content is sufficiently reduced and the battery characteristics of the lithium ion secondary battery can be effectively improved. It is a manufacturing method that can be obtained by various methods and is highly industrially useful.

Hereinafter, the present invention will be described in detail.

The method for producing a positive electrode active material composite for a lithium ion secondary battery of the present invention is a layered lithium composite oxide secondary particle composed of lithium composite oxide particles represented by the above formula (I) or formula (II). On the surface of A), lithium-based polyanion particles (B) represented by the above formula (III) or formula (IV) and having carbon (c) supported on the surface and lithium composite oxide particles are composited. This is a manufacturing method for obtaining a positive electrode active material composite for a lithium ion secondary battery.
The positive electrode active material composite for a lithium ion secondary battery is a lithium composite oxide particle represented by the above formula (I) or formula (II) on the surface of the layered lithium composite oxide secondary particles (A). A part of the layered lithium composite oxide secondary particles (A) formed by combining certain primary particles and lithium-based polyanion particles (B), or by aggregating primary particles which are lithium composite oxide particles. It is directly composited and carbon (c) is supported on the surface of the lithium-based polyanion particles (B). That is, in the positive electrode active material composite for the lithium ion secondary battery, the lithium-based polyanion particles (B) and the lithium composite oxide particles are formed so as to cover the surface of the layered lithium composite oxide secondary particles (A). The carbon (c), which is strongly composited and supported so as to densely cover the surface of the lithium-based polyanion particles (B), is the layered lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B). ), Which has a structure interposed between the gaps of), and effectively suppresses unnecessary separation between the layered lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B) while effectively suppressing the battery characteristics. It is a complex that can be enhanced. The production method of the present invention is industrially useful because it can effectively reduce the water content of the positive electrode active material composite for a lithium ion secondary battery, although it is a simple method. It is a high manufacturing method.

Specifically, the method for producing the positive electrode active material composite for a lithium ion secondary battery of the present invention is described in the following steps (X) to (Y):
(X) Layered lithium composite oxide secondary particles (A), lithium-based polyanion particles (B) in which carbon (c) is supported on the surface, and 100 parts by mass of lithium-based polyanion particles (B). A step of blending an organic solvent (D) having a boiling point of 50 ° C. to 150 ° C., which is 30 parts by mass to 3000 parts by mass, and mixing the obtained blended slurry while applying compressive force and shearing force to obtain a composite slurry. (Y) A step of drying the obtained composite slurry is provided. That is, it is a method of obtaining a positive electrode active material composite for a lithium ion secondary battery as a positive electrode active material material for a lithium ion secondary battery by mechanical treatment by a so-called wet method. In the production method of the present invention, predetermined raw material particles such as layered lithium composite oxide secondary particles (A) and lithium-based polyanion particles (B) supported by carbon (c) are blended and then finalized. There is no need to worry that the product will unnecessarily adsorb water during the process until the product is obtained, that is, during the process from the step (X) to the step (Y), and the raw material particles are described above. It is possible to effectively and efficiently obtain a positive electrode active material composite for a lithium ion secondary battery without promoting deterioration of the particles.

In the step (X), the layered lithium composite oxide secondary particles (A), the lithium-based polyanion particles (B) having carbon (c) supported on the surface, and 100 parts by mass of the lithium-based polyanion particles (B). An organic solvent (D) having a boiling point of 50 ° C. to 150 ° C., which is 30 parts by mass to 3000 parts by mass, is mixed with the mixture, and the obtained compounded slurry is mixed while applying compressive force and shearing force to form a composite slurry. Is the process of obtaining.

The layered lithium composite oxide secondary particles (A) used in the step (X) are represented by the following formula (I) or formula (II).
LiNi _a Co _b Mn _c M ¹ _x O ² ... (I)
In formula (I), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Indicates one or more elements selected from Bi and Ge. A, b, c, x are 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, Indicates a number that satisfies 0 ≦ x ≦ 0.3 and 3a + 3b + 3c + ( ^{valence of M 1} ) × x = 3).
^{_{LiNi d Co e Al f M 2}} y O 2 ··· (II)
In formula (II), M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Indicates one or more elements selected from Ge. D, e, f, y are 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ Indicates a number that satisfies y ≦ 0.3 and 3d + 3e + 3f + ( ^{valence of M 2} ) × y = 3).

Lithium-nickel composite oxide represented by the above formula (I) (so-called Li-Ni-Co-Mn oxide, hereinafter also referred to as "NCM-based composite oxide") particles, and represented by the above formula (II). The lithium nickel composite oxide (so-called Li-Ni-Co-Al oxide, hereinafter also referred to as "NCA-based composite oxide") particles are all particles having a layered rock salt structure.
These particles are formed by agglomeration of primary particles. Therefore, such layered lithium composite oxide secondary particles (A) are also similarly referred to as "NCM-based composite oxide secondary particles (A)" and "NCA-based composite oxide secondary particles (A)".

^{M 1} in the above formula (I) is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb. , Bi and Ge, one or more elements selected from.
Further, a, b, c, x in the above formula (I) are 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, 0 ≦ x ≦ 0.3, And it is a number satisfying 3a + 3b + 3c + ( ^{valence of M 1} ) × x = 3.

In the NCM-based composite oxide secondary particles (A), Ni, Co and Mn are known to have excellent electron conductivity and contribute to battery capacity and output characteristics. In view of the cycle characteristics, it is preferable that some of these transition elements are replaced by other metal elements M ^1.

Specific examples of the NCM-based composite oxide secondary particles (A) include LiNi _0.33 Co _0.33 Mn _0.34 O ₂ , LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , and LiNi _{0.33. Examples} thereof include Co _0.31 Mn _0.33 Mg 0.045 O ₂ , LiNi _0.33 Co _0.31 Mn _0.33 Zn _0.045 O _2. Among them, particles having a large amount of Ni such as _{LiNi 0.8} Co _0.1 Mn _0.1 O ₂ and LiNi _0.6 Co _0.2 Mn _0.2 O ₂ are preferable when the discharge capacity is important, and when the cycle characteristics are important. , LiNi _0.33 Co _0.33 Mn _0.34 O ₂ , LiNi _0.33 Co _0.31 Mn _0.33 Mg _0.045 O _{2 and the} like, particles having a small amount of Ni are preferable.

^{M 2} in the above formula (II) is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi. And one or more elements selected from Ge.
Further, d, e, f, y in the above formula (II) are 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ y ≦ 0.3, And it is a number satisfying 3d + 3e + 3f + ( ^{valence of M 2} ) × y = 3.

The NCA-based composite oxide secondary particles (A) are more excellent in battery capacity and output characteristics than the NCM-based composite oxide particles represented by the formula (I). In addition, due to the inclusion of Al, deterioration due to moisture in the atmosphere is unlikely to occur, and it is also excellent in safety.
Specific examples of the NCA-based composite oxide secondary particles (A) include LiNi _0.8 Co _0.1 Al _0.1 O ₂ , LiNi _0.8 Co _0.15 Al _0.03 Mg _0.03 O ₂ , and LiNi _0.8 Co _0.15 Al _0.03 Zn _0.03 O. Examples include particles consisting of _{2 mag.} Of these, particles composed of _{LiNi 0.8} Co _0.15 Al _0.03 Mg _0.03 O _{2 are preferable.}

The average particle size of the layered lithium composite oxide secondary particles (A) as primary particles is preferably 500 nm or less, more preferably 300 nm or less. The lower limit of the average particle size of the primary particles is not particularly limited, but is preferably 50 nm or more from the viewpoint of handling.
Here, the average particle size means the average value of the measured values of the particle size (length of the major axis) of several tens of particles in the observation with an electron microscope of SEM or TEM, and is synonymous with the following description. Is.

The average particle size of the layered lithium composite oxide secondary particles (A) formed by agglutination of the primary particles is preferably 25 μm or less, more preferably 20 μm or less. The lower limit of the average particle size of the secondary particles is not particularly limited, but is preferably 1 μm or more, and more preferably 5 μm or more from the viewpoint of handling.

To produce the layered lithium composite oxide secondary particles (A), for example,
A mixed powder containing a lithium compound, a nickel compound, a cobalt compound, and a manganese compound is calcined to obtain NCM-based composite oxide secondary particles (A) (manufacturing method a1), or a lithium compound, a nickel compound, and cobalt. The mixed powder containing the compound and the aluminum compound may be calcined to obtain NCA-based composite oxide secondary particles (A) (manufacturing method a2).

Specifically, in the case of the production method a1, the raw material compound, for example, a nickel compound, a cobalt compound, and a manganese compound are first dissolved in water so as to have a desired composite oxide composition to obtain an aqueous solution a.
Next, an alkaline agent such as sodium hydroxide or potassium hydroxide is added to the aqueous solution a to obtain an aqueous solution b, and the dissolved metal components are coprecipitated by a neutralization reaction to obtain a metal composite hydroxide. Then, the aqueous solution b is stirred at a temperature of 30 ° C. to 60 ° C. for 30 minutes to 120 minutes to form a metal composite hydroxide.

After stirring, it is preferable that the aqueous solution b is filtered to recover the metal composite hydroxide, washed with water, and then dried.
Next, the metal composite hydroxide and the lithium compound are dry-mixed and calcined in an oxygen atmosphere so as to have a desired composite oxide composition to obtain an NCM-based composite oxide.
Finally, the obtained fired product is washed with water, filtered, and dried to obtain NCM-based composite oxide particles (A).

In the case of the production method a2, the NCA-based composite oxide secondary particles (A) can be obtained in the same manner as in the production method a1 except that a lithium compound, a nickel compound, a cobalt compound, and an aluminum compound are used as the raw material compounds.

On the surface of the lithium composite oxide secondary particles (A) used in the step (X), the lithium-based polyanion particles (B) compounded with the lithium composite oxide particles are represented by the following formula (III) or formula (IV). ).
LiCo _p M ³ _z PO ₄ ... (III)
(In formula (III), M ³ represents Fe, Mn, Mg, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. P and z are 0.3. <Indicates a number satisfying p ≦ 1, 0 ≦ z ≦ 0.3, and 2p + ( ^{valence of M 3} ) × z = 2.
LiFe _q Mn _r M ⁴ _v PO ₄ ... (IV)
(In formula (IV), M ⁴ represents Co, Mg, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. Q, r, and v are 0 ≦ met q ≦ 1,0 ≦ r ≦ 1,0 ≦ v ≦ 0.3, and q + r ≠ 0, and shows a number satisfying × v = 2 (valence of ^{M 4) 2q + 2r +.} )
That is, the lithium-based polyanion particles (B) represented by the formula (III) contain Co alone or one or more metals (M) with Co, and the lithium-based polyanion particles represented by the formula (IV) ( B) contains a transition metal of at least one of Fe and Mn. The lithium-based polyanion particles (B) represented by the formula (III) and the lithium-based polyanion particles (B) represented by the formula (IV) both have an olivine-type structure and are good lithium ions. It is a compound that can provide conductivity.

The lithium-based polyanionic particles (B) represented by the above formula (III) are preferably 0.3 ≦ p ≦ 1 from the viewpoint of the average discharge voltage of the positive electrode active material for the secondary battery, and 0.4 ≦ p ≦ 1. Is more preferable, and 0.5 ≦ p ≦ 1 is further preferable. Specifically, for example, LiCo PO _{4 , LiCo 0.9} Mn _{0.1 PO 4,} LiCo _0.8 Mn _0.2 PO _4, LiCo _0.7 Mn _0.3 PO _4, LiCo _0.9 Fe _0.1 PO _4, LiCo _0.8 Fe _0.2 PO _4, LiCo _0.7 Fe _0.3 PO _4, LiCo _0.8 Mn _0.1 Fe _0.1 PO ₄ , among them, LiCo _{PO 4 , LiCo 0 .8} Mn _0.2 PO _4, LiCo _0.8 Fe _0.2 PO _4, LiCo _0.8 Mn _0.1 Fe _0.1 PO ₄ is preferable.

The lithium-based polyanionic particles (B) represented by the above formula (IV) are preferably 0.5 ≦ r ≦ 1 from the viewpoint of the average discharge voltage of the positive electrode active material for the secondary battery, and 0.6 ≦ r ≦. 1 is more preferable, and 0.65 ≦ r ≦ 1 is further preferable. Specifically, for example, LiMnPO ₄ , LiFe _0.1 Mn _0.9 PO ₄ , LiFe _0.2 Mn _0.8 PO ₄ , LiFe _0.15 Mn _0.75 Mg _0.1 PO ₄ , LiFe _0.19 Mn _0.75 Zr _0.03 PO ₄ , LiFe _0.3 Mn _0.7 PO ₄ , LiFe _0.4. Examples thereof include Mn _0.6 PO ₄ , LiFe _0.5 Mn _0.5 PO ₄ , and among them, LiFe _0.3 Mn _0.7 PO _{4 and} LiFe _0.2 Mn _0.8 PO ₄ are preferable.

The average particle size of the lithium-based polyanion particles (B) is preferably 20 nm to 200 nm, more preferably 30 nm to 150 nm, from the viewpoint that the positive electrode obtained by using the lithium-based polyanion particles (B) exhibits a good volumetric energy density.

The lithium ion conductivity of the lithium-based polyanionic particles (B) at 20 MPa pressurization at 25 ° C. ^{is preferably 1 × 10 -7} S / cm or more, and preferably 1 × 10 ^-6 S / cm or more. Is more preferable. The upper limit of the lithium ion conductivity of the lithium-based polyanionic particles (B) is not particularly limited.

The lithium-based polyanion particles (B) have carbon (c) supported on the surface thereof. Examples of the carbon source of such carbon (c) include cellulose nanofibers and water-soluble carbon materials.

Cellulose nanofibers, which can be a carbon source of carbon (c), are skeletal components that occupy about 50% of all plant cell walls, and can be obtained by defibrating the plant fibers constituting such cell walls to nano size. It is a lightweight and high-strength fiber that can be produced, and carbon derived from cellulose nanofibers has a periodic structure. The fiber diameter of such cellulose nanofibers is 1 nm to 100 nm, and it also has good dispersibility in water. It is firmly supported on the surface of the lithium-based polyanion particles (B) to impart electron conductivity to the lithium-based polyanion particles (B), and a useful positive electrode active material composite for a lithium ion secondary battery can be obtained.

The water-soluble carbon material that can be a carbon source of carbon (c) means a carbon material that dissolves 0.4 g or more, preferably 1.0 g or more in terms of carbon atom equivalent of the water-soluble carbon material in 100 g of water at 25 ° C. Then, when carbonized, it is present as carbon on the surface of the lithium-based polyanion particles (B). Examples of such a water-soluble carbon material include one or more selected from saccharides, polyols, polyethers, and organic acids. More specifically, for example, monosaccharides such as glucose, fructose, galactose, mannose; disaccharides such as maltose, sucrose, cellobiose; polysaccharides such as starch and dextrin; ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, butane. Polyols and polyethers such as diols, propanediols, polyvinyl alcohols and glycerins; organic acids such as citric acid, tartaric acid and ascorbic acid can be mentioned. Among them, glucose, fructose, sucrose, and dextrin are preferable, and glucose is more preferable, from the viewpoint of enhancing the solubility and dispersibility in a solvent and effectively functioning as a carbon material.

The amount of carbon (c) present on the surface of the lithium-based polyanion particles (B), that is, the atomic equivalent amount of carbon derived from cellulose nanofibers or carbon derived from a water-soluble carbon material (the amount of carbon supported) is the lithium-based polyanion particles. (B) can be confirmed as the amount of carbon measured using a carbon / sulfur analyzer.

The amount of the carbon (c) carried is preferably 0.1% by mass or more and less than 5% by mass in 100% by mass of the total amount of the lithium-based polyanionic particles (B) supported by the carbon (c), which is more preferable. Is 0.2% by mass to 4% by mass, more preferably 0.3% by mass to 3% by mass.

In order to produce lithium-based polyanionic particles (B) on which carbon (c) is supported, first,
Whether a lithium compound, a metal (M ³ ) compound ^{containing at least a cobalt compound (M 3} is synonymous with formula (III)), and a phosphoric acid compound are subjected to a hydrothermal reaction (manufacturing method b1), or a lithium compound, at least iron. ^{A metal (M 4} ) compound containing a compound or a manganese compound ^{(M 4} is synonymous with the formula (IV)) and a phosphoric acid compound may be subjected to a hydrothermal reaction (manufacturing method b2). That is, the lithium compound, the predetermined metal compound, and the phosphoric acid compound are subjected to a hydrothermal reaction, which is a so-called wet reaction, by the method of either the production method b1 or the production method b2, and the above formula (III) or formula (IV) is applied. After obtaining the lithium-based polyanion primary particles represented by), carbon may be supported on the obtained primary particles.

Specifically, as an example of a method for producing lithium-based polyanionic particles (B) in which carbon (c) is supported, a production method b2 is adopted using a lithium compound, an iron compound, a manganese compound, and a phosphoric acid compound. The case where the carbon (c) is supported after the primary particles of the lithium-based polyanion particles (B) represented by the above formula (IV) are obtained will be described below.

More specifically, the production method b2 is described in the following steps (i) to (iii):
(I) A step of mixing a phosphoric acid compound with a mixture containing a lithium compound to obtain a precursor of primary particles, and (ii) a metal salt containing the obtained precursor and at least an iron compound and / or a manganese compound. Step of subjecting the contained slurry water to a hydrothermal reaction to obtain primary particles (iii) The obtained primary particles and the slurry containing a carbon source are spray-dried, and the obtained granules are calcined to obtain primary particles. It suffices to provide a step of obtaining a fired product in which carbon is supported on the surface of the above.

In step (i), as the lithium compound which can be used, lithium hydroxide (e.g. _{LiOH, LiOH · H 2 O)} , lithium carbonate, lithium sulfate, lithium acetate, and examples of the phosphoric acid compound include orthophosphoric acid _{(H 3} PO ₄ , phosphoric acid), metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, ammonium phosphate, ammonium hydrogen phosphate and the like.
Among them, it is preferable to use phosphoric acid, add it dropwise to the mixture and add it little by little to mix, and it is preferable to purge nitrogen after mixing. Further, it is preferable that the dissolved oxygen concentration in the mixture after mixing the phosphoric acid compound is 0.5 mg / L or less.

Then, in step (ii), slurry water containing the precursor obtained in step (i) and a metal salt containing at least an iron compound and / or a manganese compound is subjected to a hydrothermal reaction.

Examples of the iron compound that can be used include iron acetate, iron nitrate, iron sulfate and the like. These may be used individually by 1 type, and may be used in combination of 2 or more type.
Examples of the manganese compound that can be used include manganese acetate, manganese nitrate, manganese sulfate and the like. These may be used individually by 1 type, and may be used in combination of 2 or more type.
Further, if necessary, as a metal salt, other than an iron compound and manganese compound metal (M ⁴⁾ may be used salts. ^{M 1} in the metal salt ^{has the same meaning as M 4} in the above formula (IV), and as such a metal salt, sulfates, halogen compounds, organic acid salts, hydrates thereof and the like can be used. These may be used alone or in combination of two or more.

The temperature of the hydrothermal reaction may be 100 ° C. or higher, preferably 130 ° C. to 180 ° C., the pressure is preferably 0.3 MPa to 0.9 MPa, and the hydrothermal reaction time is 0.1 hour to 48 hours. Is preferable.

In step (iii), the obtained primary particles and the slurry containing the carbon source are spray-dried, and the obtained granulated product is calcined to obtain a calcined product in which carbon is supported on the surface of the primary particles. Is. As the carbon source, the cellulose nanofibers or the water-soluble carbon material may be used, and these may be carbonized by firing to obtain lithium-based polyanionic particles (B) on which carbon (c) is supported. can.
The slurry to be spray-dried may be a mixture of primary particles, a carbon source, and water, and the content of the primary particles and the carbon source in the slurry is such that the carbon atom equivalent of the carbon source is obtained in the calcined product. The amount is preferably 0.1% by mass to 20% by mass.

The particle size of the granules obtained by spray drying, at D ₅₀ value in the particle size distribution based on the laser diffraction scattering method, preferably a 1 to 20 [mu] m.
The obtained granulated product is preferably calcined in a reducing atmosphere or an inert atmosphere. As the firing conditions, it is preferable that the firing temperature is 400 ° C. to 800 ° C. and the firing time is 10 minutes to 3 hours.
The lithium-based polyanion particles (B) represented by the above formula (III) on which carbon (c) is supported may also be produced according to the above-mentioned production method while appropriately selecting a raw material compound.

In the step (X) provided in the method for producing a positive electrode active material composite for a lithium ion secondary battery of the present invention, the layered lithium composite oxide secondary particles (A) and carbon (c) are supported on the surface. Lithium-based polyanion particles (B) and an organic solvent (D) having a boiling point of 50 ° C. to 150 ° C., which is 30 parts by mass to 3000 parts by mass with respect to 100 parts by mass of the lithium-based polyanion particles (B), are blended and blended. Obtain a slurry.
As described above, in the present invention, by adopting the so-called wet method in which a specific organic solvent (D) is used in a specific amount, the layered lithium composite oxide secondary particles (A) are contained in the organic solvent (D). And the lithium-based polyanion particles (B) in which carbon (c) is supported on the surface are uniformly dispersed, and the lithium-based polyanion particles (B) are formed while the layered lithium composite oxide secondary particles (A) are the core. It is finely crushed and can coat the surface of the layered lithium composite oxide secondary particles (A). In addition, during the mixing process of the compounded slurry to be added later while applying compressive force and shearing force, when the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B) are charged / blended, or at the time of charging / blending lithium ion secondary particles. It is possible to effectively prevent excessive contact with the atmosphere at the time of discharging the positive electrode active material composite for the next battery. As a result, it is possible to effectively prevent water from being adsorbed on the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B) during the process, even though it is a wet method. can.

When producing a positive electrode for a lithium secondary battery, a so-called wet method is adopted in which a positive electrode active material and a dispersion medium such as an organic solvent are mixed, but the wet method here is a method. , Different from the wet method of the present invention. For example, a positive electrode is prepared by mixing two types of particles as a positive electrode active material: lithium composite oxide secondary particles (A) and lithium-based polyanionic particles (B) that are more fragile than the particles (A) and are easily crushed. In this case, the crushing of the lithium-based polyanion particles (B) increases the viscosity and makes the obtained electrode slurry non-uniform, and the coatability as a slurry when coating the current collector deteriorates. In order to avoid the particles (B), it is necessary to set detailed mixing conditions and select a mixing device so that the lithium-based polyanion particles (B) are not crushed.
However, in the production method of the present invention, the organic solvent (D) is used in an optimum amount with respect to the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B), even though it is a wet method. By performing a specific mixing treatment while crushing the granulated product of the lithium-based polyanion particles (B), the lithium-based polyanion particles (B) are coated on the surface of the lithium composite oxide secondary particles (A). Therefore, an electrode slurry can be obtained while maintaining a low viscosity. This makes it possible to effectively improve the coatability on the current collector.

The organic solvent (D) that can be used has a boiling point of 50 ° C. to 150 ° C. and does not require unnecessary chemical reaction or dissolution with the layered lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B). , But not particularly limited as long as it does not cause physical adsorption; specifically, alcohols such as methanol, ethanol, propanol and isobutyl alcohol; ketones such as acetone, methyl ethyl ketone, diethyl ketone and methyl propyl ketone; hexane; kerosine. N-methyl-2-pyrrolidone; one or more selected from polyvinylidene fluoride and the like. Above all, ethanol is suppressed from the viewpoint of suppressing unnecessary volatilization of the organic solvent (D) due to heat in the step (X), while easily volatilizing the organic solvent (D) in the subsequent step (Y). , Propanol, acetone, hexane, one or more, preferably ethanol.

The blending amount of the organic solvent (D) is 30 to 3000 parts by mass, preferably 40 to 2500 parts by mass, and more preferably 50 to 2400 parts by mass with respect to 100 parts by mass of the lithium-based polyanionic particles (B). It is more preferably 50 to 2000 parts by mass.
Further, the mass of the blending amount of the organic solvent (D) and the blending amount of the layered lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B) having carbon (c) supported on the surface. The ratio ({(A) + (B)} / (D)) is preferably 0.2 to 10, more preferably 0.2 to 8, and even more preferably 0.2 to 6.

Mass of the amount of the lithium composite oxide secondary particles (A) and the amount of the lithium-based polyanion particles (B) on which carbon (c) is supported on the surface (including the amount of carbon (c) supported). The ratio ((A): (B)) is preferably 95: 5 to 50:50, more preferably 93: 7 to 50:50, and even more preferably 90: 10 to 50:50.

The temperature of the blended slurry is preferably 10 ° C. to 50 ° C., more preferably 10 ° C. to 45 ° C. The pH at 25 ° C. is preferably 5 to 10, more preferably 6 to 9.5.

Then, in the step (X), the obtained compounded slurry is mixed while applying a compressive force and a shearing force to obtain a composite slurry. As a mixing process while applying a compressive force and a shearing force, specifically, the crushed lithium-based polyanion particles (B) are layered while crushing the granulated body of the lithium-based polyanion particles (B). The treatment may be such that the secondary particles (A) of the type lithium composite oxide are coated, and it is preferable to perform such treatment using an apparatus equipped with an impeller or a rotor tool.

When a device equipped with such an impeller or rotor tool is used, the peripheral speed of the impeller or rotor tool effectively crushes the granulated body of the lithium-based polyanionic particles (B), and the layered lithium composite oxide secondary particles. From the viewpoint of coating (A), it is preferably 10 m / s to 40 m / s, and more preferably 12 m / s to 40 m / s. The mixing time is preferably 1 minute to 90 minutes, more preferably 2 minutes to 80 minutes. The amount of work in the mixing treatment is preferably 0.5 Wh to 75 Wh, and more preferably 1 Wh to 50 Wh.
The peripheral speed of the impeller or rotor tool means the speed of the outermost end of the rotary stirring blade (impeller) or rotor tool, and can be expressed by the following formula (1), and the compressive force and shearing force. The time required for the mixing process while adding the above may vary depending on the peripheral speed of the impeller or rotor tool so that the slower the peripheral speed of the impeller or rotor tool is, the longer the peripheral speed is.
Peripheral speed (m / s) of impeller or rotor tool =
Impeller or rotor tool diameter (m) x π x rotation speed (rpm) ÷ 60 ... (1)
The amount of work is expressed by the product of the load (W) of the device and the processing time (h), and is expressed by the following equation (2).
Work load (Wh) = device load (W) x time (h) ... (2)

Examples of the device provided with such an impeller or rotor tool include Philmix (manufactured by Primix Corporation), Henschel Mixer (manufactured by Imoto Seisakusho Co., Ltd.), and High Speeder (manufactured by Pacific Machinery & Engineering Co., Ltd.). For example, by using Philmix (manufactured by Primix Corporation), a high compressive force and a shearing force can be easily applied, which is a preferable device in the step (X).

The step (Y) provided in the method for producing a positive electrode active material composite for a lithium ion secondary battery of the present invention is a step of drying the composite slurry obtained in the step (X).
Specifically, for example, using a vacuum constant temperature dryer (VOS-301SD manufactured by Tokyo Rika Kikai Co., Ltd.), the temperature of the drying chamber is raised to 80 ° C. in advance, and then the composite slurry obtained in step (X) is added. , Vacuum pump may be used to reduce the pressure to 0.9 MPa and dry for 6 hours. Vacuum drying is preferable as the drying atmosphere, but this is not the case.
The drying temperature is preferably 50 ° C. to 150 ° C., more preferably 60 ° C. to 120 ° C. The drying time is preferably 30 minutes to 7200 minutes, more preferably 60 minutes to 1440 minutes.

In the positive electrode active material composite for a lithium ion secondary battery obtained by the production method of the present invention, the water content is preferably 3000 ppm or less, more preferably 2000 ppm or less, still more preferably 1000 ppm or less.
In the present specification, the water content is defined as the water content of the positive electrode active material composite for a lithium ion secondary battery, which is heated to 150 ° C. and held for 20 minutes, then further raised to a temperature of 250 ° C. and held for 20 minutes. The amount of water volatilized at that time was measured using a Karl Fisher Moisture Analyzer (MKC-610, manufactured by Kyoto Denshi Kogyo Co., Ltd.), and the water content in 100% by mass of the total amount of the positive electrode active material composite for lithium ion secondary batteries. It means a value converted into a quantity (mass%).

In the positive electrode active material composite for a lithium ion secondary battery obtained by the production method of the present invention, the content of the lithium composite oxide secondary particles (A) and the lithium-based polyanion in which the carbon (c) is supported on the surface. The mass ratio ((A): (B)) to the content of the particles (B) (including the amount of carbon (c) carried) is preferably 95: 5 to 50:50, more preferably 93 :. It is 7 to 50:50, more preferably 90: 10 to 50:50.

The positive electrode active material composite for a lithium ion secondary battery obtained by the production method of the present invention has carbon (c) supported on the surface of the layered lithium composite oxide secondary particles (A). The degree to which the lithium-based polyanion particles (B) and the lithium composite oxide particles are compounded can be evaluated by Raman spectroscopy. Specifically, in the Raman spectrum obtained by Raman spectroscopy, the peak intensity of carbon (c) existing on the surface of the lithium-based polyanion particles (B) (G band, around 1600 cm-1, I _(c)) is used. ) and (peak intensity derived from the binding of a transition metal and oxygen contained in a) (600 cm-1 _{around, I (a)} layered lithium composite oxide secondary particles and.) and the intensity ratio of the _{(I (a )} / I _(c) ) can be confirmed by the calculated value. Therefore, the lower the value of the intensity ratio (I _(A) / I _(c) ), the stronger the composite of the lithium-based polyanion particles (B) in which carbon (c) is supported on the surface and the lithium composite oxide particles. It is shown that the surface of the layered lithium composite oxide secondary particles (A) is well coated.
More specifically, the value of the intensity ratio (I _(A) / I _(c) ) is preferably 0.3 or less, more preferably 0.25, and further preferably 0.15 or less. be.

The positive electrode active material composite for a secondary battery of the present invention is applied as a positive electrode material, and the lithium ion secondary battery containing the positive electrode active material composite has an essential configuration of a positive electrode, a negative electrode, an electrolytic solution and a separator, or a positive electrode, a negative electrode and a solid electrolyte. There is no particular limitation as long as it does.

Here, as for the negative electrode, as long as lithium ions can be occluded at the time of charging and released at the time of discharging, the material composition is not particularly limited, and a known material composition can be used. For example, a carbon material such as lithium metal, graphite, silicon-based (Si, SiO _x ), lithium titanate, or amorphous carbon can be used. Then, it is preferable to use an electrode formed of an intercalate material capable of electrochemically occluding and releasing lithium ions, particularly a carbon material. Further, two or more kinds of the above-mentioned negative electrode materials may be used in combination, and for example, a combination of graphite and silicon can be used.

The electrolytic solution is a solution in which a supporting salt is dissolved in an organic solvent. The organic solvent is not particularly limited as long as it is an organic solvent that is usually used as an electrolytic solution for a lithium ion secondary battery. For example, carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, lactones, etc. , Oxolan compounds and the like can be used.

The type of supporting salt is not particularly limited, but is _{an inorganic salt selected from LiPF 6} , LiBF ₄ , LiClO ₄ and LiAsF ₆ , derivatives of the inorganic salt, LiSO ₃ CF ₃ , LiC (SO ₃ CF _3). ) ₂ and an organic salt selected from LiN (SO ₃ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ and LiN (SO ₂ CF ₃ ) (SO ₂ C ₄ F ₉ ), and derivatives of the organic salt. It is preferable that it is at least one of.

The separator electrically insulates the positive electrode and the negative electrode and serves to hold the electrolytic solution. For example, a porous synthetic resin film, particularly a porous film of a polyolefin polymer (polyethylene, polypropylene) may be used.

The solid electrolyte electrically insulates the positive electrode and the negative electrode and exhibits high lithium ion conductivity. For example, La _0.51 Li _0.34 TiO _2.94 , Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , Li ₇ La ₃ Zr ₂ O ₁₂ , 50Li ₄ SiO ₄・ 50Li ₃ BO ₃ , Li _2.9 PO _3.3 N _0.46 , Li _3.6 Si _0.6 P _0.4 O ₄ , Li _1.07 Al _0.69 Ti _1.46 (PO ₄ ) ₃ , Li _{1 .5 Al 0.5 Ge 1.5 (PO 4} ) 3, Li 10 GeP 2 S 12, Li 3.25 Ge 0.25 P 0.75 S 4, 30Li 2 S · 26B 2 S 3 · 44LiI, 63Li _{2 S · 36SiS 2 · 1Li 3} PO 4, 57Li 2 S · 38SiS 2 · 5Li 4 SiO 4, 70Li 2 S · 30P 2 S 5, 50Li 2 S · 50GeS 2, Li 7 P 3 S 11, Li 3.25 P _0.95 S ₄ may be used.

The shape of the lithium ion secondary battery having the above configuration is not particularly limited, and may be various shapes such as a coin type, a cylindrical type, and a square type, or an indefinite shape enclosed in a laminated outer body. ..

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[Production Example 1: Production of layered lithium composite oxide secondary particles (A)]
263 g of nickel sulfate hexahydrate, 281 g of cobalt sulfate heptahydrate, 241 g of manganese sulfate pentahydrate, and 3 L of water were mixed so that the molar ratio of Ni: Co: Mn was 1: 1: 1. Next, 25% aqueous ammonia was added dropwise to the mixed solution at a dropping rate of 300 ml / min to obtain a slurry a1 containing a metal composite hydroxide having a pH of 11 at 25 ° C.
Next, the slurry a1 was filtered and dried to obtain a mixture a2 of a metal composite hydroxide, and then 37 g of lithium carbonate was mixed with the mixture a2 by a ball mill to obtain a powder mixture a3.
The obtained powder mixture a3 was calcined by calcining at 800 ° C. for 5 hours in an air atmosphere to be crushed, and then fired at 800 ° C. for 10 hours in an air atmosphere to obtain layered lithium composite oxide secondary particles (LiNi). _0.33 Co _0.33 Mn _0.34 O ₂ , average particle size: 10 μm, BET specific surface area: 0.3 m ² / g) was obtained.

[Production Example 2: Production of Lithium-based Polyanion Particles (B) with Carbon (c) Supported on the Surface]
4071 g of LiOH · H ₂ O and 9.657 L of water were mixed to obtain slurry b1. Next, 4204 g of a 75% aqueous phosphoric acid solution was added dropwise at 40 mL / min while stirring the obtained slurry b1 for 3 minutes while maintaining the temperature at 25 ° C. to obtain a slurry b2 containing _{Li 3} PO _4.
And the resulting nitrogen purge slurry b2, added after the dissolved oxygen concentration of the slurry b2 was 0.1 mg / L, with respect to the slurry b2 total _{amount, MnSO 4 · 5H 2 O 3807g} , the FeSO ₄ · 7H 2 O 2684g To obtain the slurry b3. The molar ratio of MnSO ₄ to FeSO ₄ added (manganese compound: iron compound) was 70:30.
Next, the obtained slurry b3 was put into an autoclave, and a hydrothermal reaction was carried out at 160 ° C. for 1 hour. The pressure in the autoclave was 0.8 MPa. After the hydrothermal reaction, the produced crystals were filtered and then washed with 12 parts by mass of water per 1 part by mass of the crystals. Then, it was dehydrated with a filter press device to obtain a dehydrated cake b4.
The average particle size of the lithium-based polyanion particles in the dehydrated cake b4 was 100 nm as a result of SEM observation.
8000 g of the obtained dehydrated cake b4 was taken, and 1200 g of cellulose nanofibers (FD100F, manufactured by Daicel FineChem) and 8.5 L of water were added to obtain a slurry b5 having a solid content concentration of 30%. The obtained slurry b5 was dispersed for 10 minutes with an ultrasonic stirrer (T25, manufactured by IKA) to uniformly mix the whole, and then dried using a spray drying device (MDL-050M, manufactured by Fujisaki Electric Co., Ltd.). The granulated body b6 was obtained by spray drying at a temperature of 130 ° C.
The obtained granulated body b6 was calcined at 700 ° C. for 1 hour in an argon hydrogen atmosphere (hydrogen concentration 3%), and 2.4% by mass of carbon derived from cellulose nanofibers was supported on the lithium manganese iron phosphate. Secondary particles (LiFe _0.3 Mn _0.7 PO ₄ , carbon loading = 2.0% by mass, average particle size: 12 μm, BET specific surface area: 20.2 m ² / g) were obtained.

[Example 1]
8.1 g of layered lithium composite oxide secondary particles (A) obtained in Production Example 1, 0.9 g of lithium-based polyanion particles (B) obtained in Production Example 2, anhydrous ethanol (Fuji Film Wako Pure Chemical Industries, Ltd.) 6g was collected and kneaded for 10 minutes at 12000 rpm (peripheral speed of impeller: 28.9 m / s) using Philmix 30-L type (imperator diameter: 23 mm) manufactured by Prymix. , A composite slurry x was obtained. At this time, the electric power during operation of the compounding device was 33 W, and the workload was 5.5 Wh. Next, the obtained composite slurry x was dried in a vacuum dryer at 80 ° C. for 6 hours to obtain a positive electrode active material composite for a lithium ion secondary battery. At this time, the peripheral speed (m / s) of the impeller was a value calculated from peripheral speed (m / s) = impeller diameter (m) × π × rotation speed / 60. The work amount was set as a value calculated from the product of work amount (Wh) = electric power (W) during operation of the compounding device × device operation time (h).

[Example 2]
Example 1 except that 6.3 g of layered lithium composite oxide secondary particles (A) and 2.7 g of lithium-based polyanion particles (B) were collected and the conditions in the compounding apparatus were set to the values shown in Table 1. In the same manner as above, a positive electrode active material composite for a lithium ion secondary battery was obtained.

[Example 3]
Example 1 except that 4.5 g of layered lithium composite oxide secondary particles (A) and 4.5 g of lithium-based polyanion particles (B) were collected and the conditions in the compounding apparatus were set to the values shown in Table 1. In the same manner as above, a positive electrode active material composite for a lithium ion secondary battery was obtained.

[Example 4]
6.3 g of layered lithium composite oxide secondary particles (A), 2.7 g of lithium-based polyanion particles (B), and 9 g of anhydrous ethanol were collected, and the conditions in the compounding apparatus were set to the values shown in Table 1. Except for the above, a positive electrode active material composite for a lithium ion secondary battery was obtained in the same manner as in Example 1.

[Example 5]
6.3 g of layered lithium composite oxide secondary particles (A), 2.7 g of lithium-based polyanion particles (B), and 2 g of anhydrous ethanol were collected, and the conditions in the compounding apparatus were set to the values shown in Table 1. Except for the above, a positive electrode active material composite for a lithium ion secondary battery was obtained in the same manner as in Example 1.

[Example 6]
2.1 g of layered lithium composite oxide secondary particles (A), 0.9 g of lithium-based polyanion particles (B), and 15 g of anhydrous ethanol were collected, and the conditions in the compounding apparatus were set to the values shown in Table 1. Except for the above, a positive electrode active material composite for a lithium ion secondary battery was obtained in the same manner as in Example 1.

[Example 7]
A positive electrode active material composite for a lithium ion secondary battery was obtained in the same manner as in Example 2 except that the organic solvent (D) was methanol and the conditions in the compounding apparatus were set to the values shown in Table 1.

[Example 8]
A positive electrode active material composite for a lithium ion secondary battery was obtained in the same manner as in Example 2 except that the organic solvent (D) was 2-propanol and the conditions in the compounding device were the values shown in Table 1.

[Example 9]
A positive electrode active material composite for a lithium ion secondary battery was obtained in the same manner as in Example 2 except that the organic solvent (D) was acetone and the conditions in the compounding apparatus were set to the values shown in Table 1.

[Examples 10 to 13]
A positive electrode active material composite for a lithium ion secondary battery was obtained in the same manner as in Example 2 except that the organic solvent (D) was n-hexane and the conditions in the compounding apparatus were the values shown in Table 1.

[Examples 14 to 15]
A positive electrode active material composite for a lithium ion secondary battery was obtained in the same manner as in Example 2 except that the conditions in the compounding apparatus were set to the values shown in Table 1.

[Comparative Example 1]
Water was used instead of the organic solvent (D), and a positive electrode active material composite for a lithium ion secondary battery was obtained in the same manner as in Example 2 except that the conditions in the compounding apparatus were set to the values shown in Table 1.

[Comparative Example 2]
450 g of layered lithium composite oxide secondary particles (A) and 50 g of lithium-based polyanion particles (B) were collected and composited using Nobilta (manufactured by Hosokawa Micron, NOB-130) at 2000 rpm for 5 minutes, so-called dry method. Mixing was carried out to obtain a positive electrode active material composite for a lithium ion secondary battery.

[Comparative Example 3]
A positive electrode active material composite for a lithium ion secondary battery was obtained in the same manner as in Comparative Example 4, except that 350 g of the layered lithium composite oxide secondary particles (A) and 150 g of the lithium-based polyanion particles (B) were collected.

[Comparative Example 4]
250 g of layered lithium composite oxide secondary particles (A) and 250 g of lithium-based polyanionic particles (B) were collected, and the compounding treatment was performed for 15 minutes, but for a lithium ion secondary battery in the same manner as in Comparative Example 4. A positive electrode active material composite was obtained.

<< Evaluation of discharge capacity in lithium-ion secondary batteries >>
2.7 g of the obtained positive electrode active material composite for a lithium ion secondary battery was used as a positive electrode active material, and 0.150 g of polyvinylidene fluoride (PVDF), 4.2 mL of N-methyl-2-pyrrolidone (NMP) and 0.1500 g of acetylene black was added, and the mixture was kneaded at 5000 rpm for 5 minutes using a rotating / revolving mixer (Awatori Rentaro (registered trademark) ARE-310, manufactured by THINKY) to obtain a paste. Next, the obtained paste was applied to a current collector of aluminum foil, dried in a vacuum dryer at 80 ° C. for 6 hours, and then pressed to obtain a positive electrode for a lithium ion secondary battery. Next, a coin battery was produced using the obtained positive electrode.
Using the obtained coin battery, a discharge capacity measuring device (HJ-1001SD8, manufactured by Hokuto Denko Co., Ltd.) is used to discharge capacities of 0.1C (17mAh / g) and 3C (510mAh / g) in an environment of a temperature of 30 ° C. Was measured.

<< Evaluation of the degree of coating of lithium-based polyanionic particles (B) on the surface of layered lithium composite oxide secondary particles (A) >>
The Raman spectrophotometer (NRS-1000, manufactured by JASCO Corporation) was used to measure the Raman spectroscopic spectrum, and _{the peak intensities (I (A)} ^{) near 1600 cm -1} (G band) and the peak intensities around 600 cm ^{-1 (G band) were measured.} I _(C) ) was obtained, the strength ratio (I _(A) / I _(C) ) was calculated, and the degree of coating was evaluated.
The smaller the value of the strength ratio, the stronger the lithium-based polyanion particles (B) are coated on the surface of the layered lithium composite oxide secondary particles (A).

<< Measurement of water content of positive electrode active material composite for lithium ion secondary battery >>
The amount of water volatilized when the obtained positive electrode active material composite for a lithium ion secondary battery was heated to 150 ° C. and held for 20 minutes, and then further raised to a temperature of 250 ° C. and held for 20 minutes was curled. It was measured using a Fisher Moisture Analyzer (MKC-610, manufactured by Kyoto Denshi Kogyo Co., Ltd.), and a value converted into a water content (mass%) was calculated.

According to the results in Tables 1 and 2, the positive electrode active material composite for a lithium ion secondary battery obtained by the production method of Examples is the positive electrode active material for a lithium ion secondary battery obtained by the production method of Comparative Example. It can be seen that the water content is effectively reduced, although the battery characteristics are the same as those of the composite.

Claims (6)

The following formula (I) or formula (II):
LiNi _a Co _b Mn _c M ¹ _x O ² ... (I)
In formula (I), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Indicates one or more elements selected from Bi and Ge. A, b, c, x are 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, Indicates a number that satisfies 0 ≦ x ≦ 0.3 and 3a + 3b + 3c + ( ^{valence of M 1} ) × x = 3).
^{_{LiNi d Co e Al f M 2}} y O 2 ··· (II)
In formula (II), M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Indicates one or more elements selected from Ge. D, e, f, y are 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ Indicates a number that satisfies y ≦ 0.3 and 3d + 3e + 3f + ( ^{valence of M 2} ) × y = 3).
On the surface of the layered lithium composite oxide secondary particles (A) composed of lithium composite oxide particles represented by, the following formula (III) or formula (IV):
LiCo _p M ³ _z PO ₄ ... (III)
(In formula (III), M ³ represents Fe, Mn, Mg, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. P and z are 0.3. <Indicates a number satisfying p ≦ 1, 0 ≦ z ≦ 0.3, and 2p + ( ^{valence of M 3} ) × z = 2.
LiFe _q Mn _r M ⁴ _v PO ₄ ... (IV)
(In formula (IV), M ⁴ represents Co, Mg, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. Q, r, and v are 0 ≦ met q ≦ 1,0 ≦ r ≦ 1,0 ≦ v ≦ 0.3, and q + r ≠ 0, and shows a number satisfying × v = 2 (valence of ^{M 4) 2q + 2r +.} )
A method for producing a positive electrode active material composite for a lithium ion secondary battery, which is represented by a composite of lithium-based polyanion particles (B) having carbon (c) supported on its surface and lithium composite oxide particles. Then, the next steps (X) to (Y):
(X) With respect to 100 parts by mass of the layered lithium composite oxide secondary particles (A), the lithium-based polyanion particles (B) having carbon (c) supported on the surface, and the lithium-based polyanion particles (B). A step of blending an organic solvent (D) having a boiling point of 50 ° C. to 150 ° C., which is 30 parts by mass to 3000 parts by mass, and mixing the obtained compounded slurry while applying compressive force and shearing force to obtain a composite slurry. (Y) A method for producing a positive electrode active material composite for a lithium ion secondary battery, which comprises a step of drying the obtained composite slurry. In the step (X), the blending amount of the organic solvent (D), the layered lithium composite oxide secondary particles (A), and the lithium-based polyanion particles (B) in which the carbon (c) is supported on the surface are blended. The method for producing a positive electrode active material composite for a lithium ion secondary battery according to claim 1, wherein the mass ratio to the amount ({(A) + (B)} / (D)) is 0.2 to 10. In step (X), the process of mixing the compounded slurry while applying compressive force and shearing force is a process performed using an apparatus equipped with an impeller or rotor tool, and the peripheral speed of the impeller or rotor tool is 10 m / s to The method for producing a positive electrode active material composite for a lithium ion secondary battery according to claim 1 or 2, which is a process for setting the work amount to 0.5 Wh to 75 Wh at 40 m / s. The organic solvent (D) is one or 2 selected from methanol, ethanol, propanol, isobutyl alcohol, acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, hexane, kerosine, N-methyl-2-pyrrolidone, and polyvinylidene fluoride. The method for producing a positive electrode active material composite for a lithium ion secondary battery according to any one of claims 1 to 3, which is more than one species. The lithium ion secondary according to any one of claims 1 to 4, wherein in the step (Y), the treatment for drying the composite slurry is a treatment at a temperature of 50 ° C. to 150 ° C. for a time of 30 minutes to 7200 minutes. A method for producing a positive electrode active material composite for a battery. The method for producing a positive electrode active material composite for a lithium ion secondary battery according to any one of claims 1 to 5, wherein the water content of the positive electrode active material composite for a lithium ion secondary battery is 3000 ppm or less.