JPH09241026A - Lithium nickel multiple oxide, its production and it use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a large capacity battery by mixing a Li source material and a Ni source material in a specified atomic ratio of Li/Ni and calcining the mixture in an inert gas flow to form a Li-Ni multiple oxide expressed by specified compsn. formula. SOLUTION: A Li compd. such as Li2 O and a Ni compd. such as NiO are mixed in a dry atmosphere by 2.0/1.0 to 2.5/1.0 molar ratio of Li/Ni. The mixture is formed into a specified shape and calcined in an inert gas flow such as a gaseous nitrogen at 400 to 750 deg.C for about 12 hours to obtain a Li-Ni multiple oxide expressed by Li2+x Ni1-x O2 , wherein x satisfies 0.0<x<1/7. In this multiple oxide, planer quadruple coordinate structures of NiO4 having common sides facing each other are connected to form a one-dimensional chain and NiO4 chains of the planer quadruple coordinate structure are arranged parallel to each other so that the planes face each other. A nonwater-base secondary cell can be obtd. by using a positive pole containing the obtd. multiple oxide as an active material for the positive pole, a negative pole containing a Li metal or a material which can occlude and release Li, and an ionic conductive material.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel lithium nickel composite oxide and a method for producing the same, and in particular, the lithium nickel composite oxide of the present invention is capable of charging and discharging a large capacity and having excellent cycle characteristics. And can be usefully used for non-aqueous secondary batteries. In addition to the battery material, the novel lithium nickel oxide of the present invention is expected to be used as a catalyst, an adsorbent, a dielectric, and a magnetic material.

[0002]

2. Description of the Related Art Secondary batteries are often used as a power source for portable devices in terms of economy. There are various types of secondary batteries, and the nickel-cadmium battery is the most common at present, and the nickel-hydrogen battery is becoming popular recently. However, since lithium secondary batteries using lithium have higher output voltage and higher energy density than these secondary batteries, they have been partially put into practical use and have been actively researched in recent years to further improve performance. There is. The commercially available positive electrode material for this lithium secondary battery is LiCo.
O ₂ . However, since cobalt, which is a raw material of LiCoO ₂ , is expensive, LiNiO ₂ using nickel, which is a cheaper raw material, has the same crystal structure and almost the same electrochemical behavior, and is a next-generation lithium It is considered to be a positive electrode material for secondary batteries.

Li as a lithium nickel composite oxide
It is known that NiO ₂ exists most stably and can be synthesized relatively easily. Since LiNiO ₂ exists in the state of Ni ^{3+ in} the crystal, when LiNiO ₂ is used as the positive electrode, lithium is electrochemically extracted from the structure by charging. Sometimes nickel will be oxidized from 3+ to 4+. Since the maximum oxidation number of nickel is 4+ and further oxidation cannot be performed, even if all the lithium can be electrochemically extracted by charging it, its electric capacity is 1 electron equivalent. The above cannot be achieved, that is, the theoretical capacity cannot be more than 274.6 mAh / g.

Under the present circumstances, when LiNiO ₂ is used as a positive electrode active material of a lithium secondary battery and is operated as an actual battery, the capacity as a positive electrode is only about half of these theoretical capacities. Electrochemically, it is possible to obtain a capacity of about 70 to 80% of their theoretical capacities, but in that case the cycle performance becomes extremely poor, and it becomes impossible to construct a practical secondary battery. This is LiNiO
₂ is a so-called layered structure, which is composed of a Li layer and a NiO layer, and when lithium is extracted too much from the lithium layer, the repulsion between the NiO layers becomes large, the structure cannot be maintained, and the crystal structure itself collapses. Further, when lithium is removed, nickel in the NiO layer may fall into the lithium site, which may hinder the diffusion of lithium, resulting in a decrease in capacity.

Various methods have been adopted in order to improve these points, but the above-mentioned properties come from the basic structure of LiNiO ₂ , and at present, no fundamental improvements have been made. As described above, the known lithium nickel composite oxide has a fundamental problem, and it is desired to use a novel positive electrode active material in order to provide a lithium secondary battery having excellent characteristics, particularly a large capacity. ing.

On the other hand, as the negative electrode, a lithium alloy such as metallic lithium or lithium aluminum, a carbon material, or a substance capable of inserting / releasing lithium ions, for example, a conductive polymer such as polyacetylene, polythiophene, polyparaphenylene, or transition. Metal oxides, transition metal sulfides, transition metal nitrides, lithium transition metal oxides, lithium transition metal sulfides, lithium transition metal nitrides and the like can be used alone or as a composite. Among these, since lithium metal or lithium aluminum alloy has a large capacity per unit weight, a high energy density secondary battery can be constructed. However, when lithium or lithium aluminum is repeatedly charged and discharged, dendrites, so-called dendrites are formed on the lithium metal surface. The grown dendrite eventually comes into contact with the positive electrode, causing a short circuit inside the battery, and in the worst case, there is a risk of ignition. Therefore, as the negative electrode for the secondary battery, it is preferable to use a material other than these metallic lithium or lithium aluminum alloy, which utilizes the insertion-elimination reaction of lithium ions into the interior, but the energy density and the price thereof. Therefore, carbon materials are considered to be the most promising.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and uses a lithium-nickel composite oxide having a structure that has not existed in the past, and has a new capacity that is larger than the conventional capacity. Another object of the present invention is to provide a high-capacity secondary battery by combining the new positive-electrode active material with a carbon material or the like.

[0008]

[Means for Solving the Problems] In order to overcome the above-mentioned problems, the inventors have searched for a new material which replaces the conventional LiNiO ₂ . When attempting to electrochemically desorb lithium or other alkali metal and extract chemical energy therefrom, in order to obtain a larger energy density, more lithium or alkali metal should be desorbed. Need to be separated. However, if the elements constituting the original crystal are excessively desorbed, the structure of the crystal itself cannot be maintained and the crystal collapses, resulting in a decrease in capacity. In order to prevent this, if a crystal containing a large amount of lithium or alkali metal is synthesized beforehand and these elements are desorbed from it, crystal collapse does not occur and an electrode material with a large energy density is obtained. I thought that it would be possible to overcome the above problems.

The present inventors have studied various compounds by paying attention to this point, and found that Li _{2 + x} Ni _1-x O ₂ (0.0 <x ≦) having a completely different structure from LiNiO _2. 1
It has been found that a novel lithium nickel composite oxide represented by / 7) can be synthesized by a solid phase reaction, and this is a very promising electrode material.

Li _{2 + x} Ni _1-x O ₂ (0.0 <x
In the case of ≤ 1/7), lithium is present in the structure in an amount twice or more that of nickel. Further, nickel has an average valence of 2+ to 4+, and nickel itself has a valence of 2+ to 4+.
Since the valence of + can be taken, Li _{2 + x} Ni _1-x O ₂ (0.0
There is a possibility that 1 to 2 lithium can be electrochemically desorbed from <x ≦ 1/7). If the composition formula is Li _2.14 Ni
_{In the case of 0.86} O ₂ (x = 1/7), it can be seen that if one lithium is desorbed from this, about 275 mAh / g, and if two are desorbed, it has a very large capacity of about 550 mAh / g. In the case of LiNiO ₂ , assuming that lithium is completely desorbed, the amount is about 275 mAh / g, but about half of that is practically usable. Li _{2 + x} Ni _{1-x of the} present invention
With O ₂ (0.0 <x ≦ 1/7), a very large capacity of about 275 mAh / g can be obtained even if half of the total lithium is used.

LiN as a lithium nickel composite oxide
It is known that Li ₂ NiO ₂ exists in addition to iO ₂ . However, Li ₂ NiO ₂ has not been previously reported to be synthesized by the solid phase method, and is reported to be obtained by electrochemically inserting lithium into LiNiO ₂ (H. Rieck et.al., Z.
Anorg. Allg. Chem., 392 (1972) 193, JRDahn et.al.,
Solid State Ionic 44 (1990) 87, I. Davidson et.al.,
Solid State Ionics 46 (1991), IJDavidson et.al.,
Solid State Chem, 105 (1993) 410). L in the present invention
i _{2 + x} Ni _1-x O ₂ (0.0 <x ≦ 1/7) is Li ₂ NiO
It is a new compound with a structure very similar to ₂ , but a different structure with a different ratio of lithium and nickel.

FIG. 1 shows the Li ₂ synthesized by the same method as the present invention.
NiO ₂ and Li _{2 + x} Ni _1-x O ₂ (0.0 <x ≦ 1 of the present invention
/ 7) C from the enclosed X-ray tube targeting Cu
3 shows a powder X-ray diffraction pattern using uK _α rays. The X-ray diffraction pattern of the substance was 2θ = 19.6 ± 0.5, 25.
6 ± 0.5, 44.3 ± 0.5, 45.3 ± 0.5, 4
It has peaks in the ranges of 8.5 ± 0.5 and 58.0 ± 0.5, and the peak intensity ratio is 2θ = 25.6.
The peak existing at ± 0.5 ° is defined as the strongest intensity, which is 10
When standardized as 0, 20-35, 100,
28-35, 18-22, 10-14, 17-20. By indexing this diffraction pattern, it was confirmed that Li _{2 + x} Ni _1-x O ₂ (0.0 <x ≦ 1/7) of the present invention belongs to the space group Immm. Further, as a result of powder X-ray structural analysis using the Rietveld method based on this space group, the results obtained when it was considered that lithium was located at the 4j site, nickel at the 2b site, and lithium and oxygen at the 4i site were found. It showed the best agreement with the most measured pattern.

FIG. 2 shows the Li _{2 + x} Ni _1-x O ₂ (0.
The basic structure of 0 <x ≦ 1/7) is shown. Known Li ₂
NiO ₂ has lithium at 4j site, only nickel at 2b site has oxygen atom at 4I site, and has Li _{2 + x} Ni _1-x O ₂ (0.
It can be said that it is completely different from 0 <x ≦ 1/7).

Li _{2 + x} Ni _1-x O ₂ (0.0 <x
≦ 1/7) has a basic structure of plane tetracoordinated NiO ₄ or plane tetracoordinated LiO ₄ (below, plane tetracoordinated (Ni-L)
i) O ₄ ) are connected in a one-dimensional linear form sharing the opposite sides, and the respective straight lines are positioned in parallel so that their respective faces face each other, which is a kind of layer (hereinafter referred to as (Ni -Li) O ₄ layer) is formed,
Further, it has a structure in which lithium exists between the (Ni-Li) O ₄ layer and the (Ni-Li) O ₄ layer.

Further, although lithium is located between the (Ni-Li) O ₄ layers, its positional relationship with oxygen corresponds to the center of the tetrahedral site having four oxygen as vertices, and is paraphrased as a LiO ₄ tetrahedral layer. You can also In the case of LiNiO ₂ ,
Lithium is located between the NiO ₆ layers and can be said to be a LiO ₆ octahedron from the positional relationship with oxygen. As is clear from the examples of tetrahedral and octahedral sites in the spinel structure,
The tetrahedral site is more advantageous for the diffusion of lithium, which means that the Li _{2 + x} Ni of the present invention is more advantageous than LiNiO _2.
1-x O ₂ (0.0 <x ≦ 1/7) diffuses Li more quickly and can be expected to have charge / discharge characteristics at a large current.

FIG. 3 shows Li _2.05 Ni _0.95 O ₂ and Li _2.14 N.
The i _0.86 O ₂ of Cu shows a powder X-ray diffraction pattern of the inclusion X-ray tube in which a target has a radiation source. Comparing the two, there is no big difference, but 2θ = 19.6 ± 0.5, 133.
The peak intensities near 8 ± 0.5 are slightly different, indicating that part of nickel is replaced with lithium.

Li _{2 + x} Ni _1-x O ₂ (0.0 <x
≤ 1/7), nickel acetate, nickel amidosulfate, diammonium nickel (II) sulfate (hexahydrate), nickel benzoate, nickel bromide, basic nickel carbonate, nickel carbonyl, nickel chloride,
Nickel citrate, nickel cyanide, nickel diphosphate, nickel 2-ethylhexanoate, nickel fluoride nickel formate, nickel hydroxide nickel hypophosphite, nickel iodide, nickel lactate, nickel naphthenate, nickel nitrate, olein Nickel oxalate, nickel oxalate, nickel monoxide, dinickel trioxide, nickel perchlorate, nickel phosphate, nickel phosphinate, nickel pyrophosphate, nickel stearate, nickel sulfate, nickel sulfide, nickel tartrate, nickel metal One or more nickel raw materials selected from the group and metallic lithium, lithium oxide, lithium peroxide, lithium sulfide, lithium nitride, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium hydroxide , Lithium nitrate, Lithium carbonate Beam, formic acid lithium, lithium acetate,
Lithium benzoate, lithium citrate, lithium lactate,
At least one lithium raw material selected from the group consisting of lithium oxalate, lithium pyruvate, lithium stearate, and lithium tartrate was used.

Li _{2 + x} Ni _1-x O ₂ (0.0 <x ≦ 1 /
It is preferable to use those which are Ni ²⁺ in feed stage because in 7) in present in the form of a little nickel Ni ^2+, more preferably NiO.

These raw materials were mixed and fired so that the ratio of lithium to nickel was 2.01: 0.99 to 2.14: 0.86, and Li _{2 + x} Ni _1-x O ₂ ( 0.0 <x
≦ 1/7) could be obtained. If the firing temperature is too low, the reactivity is poor, so long-term firing is required to obtain a single phase, and conversely, if the temperature is too high, lithium sublimation-scattering is severe and the production cost is high. Will be higher. Further, at a temperature of 750 ° C. or higher, NiO is stabilized and the reactivity becomes extremely poor, and Li _{2 + x} Ni
_1-x O ₂ (0.0 <x ≤ 1/7) could not be synthesized and the raw material Li
Only a mixture of ₂ O and NiO can be obtained. Therefore, the preferable firing temperature is 400 ° C to 750 ° C.

The atmosphere during firing was 99.9% or more of an inert gas. As the inert gas, one or more kinds of gas selected from the group consisting of nitrogen, helium, neon, argon and krypton can be used.
If the inert gas is about 0.1%, H ₂ O,
Even if O ₂ , CO _2, etc. are contained as impurities, there is no effect. As mentioned above, since we want to synthesize nickel in the 2+ state, when synthesizing Li _{2 + x} Ni _1-x O ₂ (0.0 <x ≦ 1/7), the oxygen partial pressure is lower than that in the atmosphere. Is preferable, and more preferably 0.1% in terms of oxygen volume fraction.
It is as follows.

When a part of nickel is replaced with lithium,
The amount of lithium that can be taken out is large, and since nickel with a large atomic weight is replaced by lithium with a small atomic weight, the mass per unit volume becomes smaller and the capacity per unit weight increases, but on the other hand, the charge Since the amount of nickel to be compensated for decreases, it leads to a decrease in capacity. Also becomes possible when replacing nickel with lithium planar four-coordinate is an electron conduction path (Ni-Li) O ₄ one-dimensional chains are separated in the middle, as a positive electrode for a lithium secondary battery as a result the electron conductivity becomes poor The overall performance of the is reduced. Further, in the region of x> 1/7 or more, the raw material Li remains, and the practical replacement limit is x
≦ 1/7. Further, in the range of X <0, the nickel raw material was always left in some form. X <0 and x> 1/7
Although Li _{2 + x} Ni _1-x O ₂ can be synthesized even in the above range, the raw material remains in some form as described above, which is not preferable for use as an electrode material.

[0022] In order to form an electrode of a lithium secondary battery using Li _2.14 Ni _0.86 O ₂ of the present invention, the Li _2.14 Ni _0.86 O ₂ powder as the positive electrode active material, this conductive agent, a binder and In some cases, it is formed by mixing solid electrolytes. A carbon material such as acetylene black and graphite powder, metal powder, and conductive ceramics can be used as the conductive agent, but the conductive material is not limited thereto. As the binder, a fluorine-based polymer such as polytetrafluoroethylene or polyvinylidene fluoride, or a polyolefin-based polymer such as polyethylene or polypropylene can be used, but the binder is not limited thereto. The mixing ratio of these is 1 to 50 parts by weight of the conductive agent with respect to 100 parts by weight of lithium nickel oxide.
The amount of the binder and the binder may be 1 to 50 parts by weight.
If the amount of the conductive agent is less than 1 part by weight, the resistance or polarization of the electrode increases and the capacity of the electrode decreases, so that a practical lithium secondary battery cannot be constructed. On the other hand, if the amount of the conductive agent is more than 50 parts by weight, the amount of lithium nickel oxide in the electrode is reduced and the capacity is reduced, which is not preferable. If the amount of the binder is less than 1 part by weight, the binding ability will be lost and the electrode cannot be formed. Also, the binder is 3
If the amount is more than 0 parts by weight, the resistance or polarization of the electrode increases, and the amount of lithium nickel oxide in the electrode decreases, so that the capacity decreases, which is not practical. The positive electrode can be constituted by a method in which these mixtures are pressed onto a current collector or dissolved in a solvent such as N-methyl-2-pyrrolidone to form a slurry, which is applied to the current collector and dried. A conductive material such as a metal foil, a metal mesh, or a metal non-woven cloth can be used as the current collector. The material and shape of the current collector are not limited to these.

Further, the negative electrode in the non-aqueous secondary battery of the present invention is a lithium alloy such as metallic lithium or lithium aluminum, or a substance capable of inserting and releasing lithium ions, such as polyacetylene, polythiophene, polyparaphenylene, etc. Polymer, pyrolytic carbon, pyrolytic carbon vapor-decomposed in the presence of a catalyst, carbon calcined from pitch, coke, tar, etc., carbon obtained by calcining macromolecules such as cellulose and phenol resin, natural Graphite, artificial graphite,
A graphite material such as expanded graphite, a substance capable of intercalating / deintercalating lithium ions such as WO ₂ and MoO ₂ or a complex thereof can be used, but among them, gas phase decomposition in the presence of decomposed carbon and a catalyst. Pyrolysis carbon, pitch, coke,
Carbon materials such as carbon calcined from tar and the like, carbon obtained by calcining polymers such as cellulose and phenol resin, natural graphite, artificial graphite and expanded graphite are preferable. The negative electrode can be formed by a method in which these mixtures are pressed onto a current collector or dissolved in a solvent such as N-methyl-2-pyrrolidone to form a slurry, which is applied to the current collector and dried.

As the current collector, a conductive material such as a metal foil, a metal mesh or a metal non-woven cloth can be used. The material and shape of the current collector are not limited to these.

Further, as the ionic conductor in the non-aqueous secondary battery of the present invention, for example, an organic electrolytic solution, a polymer solid electrolyte, an inorganic solid electrolyte, a molten salt or the like can be used, and among them, the organic electrolytic solution is preferable. . The organic electrolyte is composed of an organic solvent and an electrolyte.

Examples of the organic electrolyte include esters such as propylene carbonate, ethylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate and γ-butyrolactone, and substituted hydrofurans such as tetrahydrofuran and 2-methyltetrahydrofuran, dioxolane and diethyl. Ethers such as ether, dimethoxyethane, diethoxyethane, methoxyethoxyethane, dimethyl sulfoxide,
Examples thereof include sulfolane, methylsulfolane, acetonitrile, methyl formate, methyl acetate and the like. These organic solvents may be used alone or in combination of two or more.

Examples of the electrolyte include lithium salts such as lithium perchlorate, lithium borofluoride, lithium hexafluorophosphate, lithium arsenate hexafluoride, lithium trifluoromethanesulfonate, lithium halides and lithium chloroaluminate. At least one of these can be used.

The solvent and the electrolytic solution are not limited to the above. The electrolytic solution is preferably dehydrated with active aluminum, metallic lithium or the like, and the water content thereof is preferably 1000 ppm or less, more preferably 100 ppm. Further, a dehydrated electrolyte or solvent may be used instead of the dehydration step, or a dehydrated solute and an electrolyte may be used.

The non-aqueous secondary battery in the present invention is constructed by bonding the positive electrode and the current collector, and the negative electrode and the current collector to the external electrodes, respectively, and further interposing the ion conductor therebetween. It If necessary, a separator such as porous polyethylene or porous polypropylene may be interposed together with the ionic conductor. The material and shape of the separator are not limited to these. Furthermore, it is preferable to perform packing or hermetic sealing of polypropylene or polyethylene so that the external electrodes to which the positive electrode and the negative electrode are joined do not come into contact with each other. These battery manufacturing steps are preferably carried out in an inert atmosphere such as argon or in extremely dry air in order to prevent the entry of water.

The shape of the non-aqueous secondary battery of the present invention is not particularly limited, and examples thereof include a cylindrical type, a button type, a prismatic type and a sheet type.

The operation of the present application will be described below.

According to the present invention, the composition formula is Li _{2 + x} Ni _1-x
There is provided a novel lithium nickel composite oxide characterized by comprising O ₂ (0.0 <x ≦ 1/7).

According to the production method of the present invention, nickel acetate,
Nickel amidosulfate, diammonium nickel (II) sulfate (hexahydrate), nickel benzoate, nickel bromide,
Basic nickel carbonate, nickel carbonyl, nickel chloride, nickel citrate, nickel cyanide, nickel diphosphate, nickel 2-ethylhexanoate, nickel fluoride nickel formate, nickel hydroxide nickel hypophosphite,
Nickel iodide, nickel lactate, nickel naphthenate, nickel nitrate, nickel oleate, nickel oxalate,
One selected from the group consisting of nickel monoxide, dinickel trioxide, nickel perchlorate, nickel phosphate, nickel phosphinate, nickel pyrophosphate, nickel stearate, nickel sulfate, nickel sulfide, nickel tartrate, and nickel metal. Alternatively, two or more kinds of nickel raw materials and metallic lithium, lithium oxide, lithium peroxide, lithium sulfide, lithium nitride, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium hydroxide, lithium nitrate, lithium carbonate, One or more nickel raw materials selected from the group consisting of lithium formate, lithium acetate, lithium benzoate, lithium citrate, lithium lactate, lithium oxalate, lithium pyruvate, lithium stearate, and lithium tartrate. , Lithium and nickel The molar ratio of 2.0: 1.0
By mixing so as to be 2.5: 1.0 and firing under an inert gas or oxygen-inert gas mixed gas flow,
A lithium nickel composite oxide characterized by forming a lithium nickel composite oxide represented by Li _{2 + x} Ni _1-x O ₂ (0.0 <x ≦ 1/7) is easily manufactured.

The lithium nickel composite oxide of the present invention is
Since one Ni has two Lis, even if one or more Lis are desorbed, one Li still remains.
i remains, the crystal structure can be sufficiently maintained, and the state at this time (Li _2.14 Ni _0.86 O ₂ → Li _1.14 N
In i _0.86 O ₂ ), only 50% of the existing Li was released, and the change in the lattice volume itself was extremely small as compared with LiCoO ₂ or the like, and a positive electrode active material excellent in cycle characteristics can be provided.

In the lithium-nickel composite oxide of the present invention, if one lithium is lost, about 275 mAh / g,
It is possible to provide a positive electrode active material having a very large capacity of about 550 mAh / g if two more are omitted.

Further, since the lithium nickel composite oxide of the present invention uses Ni, which is relatively inexpensive, as a raw material, Co
It is possible to obtain a positive electrode active material and a non-aqueous secondary battery, which have extremely low raw material prices and high industrial value as compared with.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION Specific examples will be shown below.
The present invention is in no way limited thereby.

Example 1 A positive electrode active material was synthesized by the following method.

First, NiO and Li ₂ O have an atomic ratio of Li and Ni of 2.05: 0.95 (x = 1/20), 2.14:
Weighed to be 0.86 (x = 1/7) and mixed in a mortar. This is hydraulically pressed at 150 k / cm ²
The pressure was applied to form a disk having a diameter of 8 mm and a thickness of 3 mm. Up to this point, the work of weighing-mixing-press forming is 1% humidity.
The following was performed in dry air. The pellets thus obtained were placed on a porcelain boat, and nitrogen gas was introduced into the electric furnace. After the atmosphere in the electric furnace was sufficiently replaced with nitrogen gas, the temperature of the electric furnace was raised from room temperature to 750 ° C. and kept at 750 ° C. for 12 hours. Nitrogen gas was flowed at a flow rate of 2 l / min during the temperature rise and the holding time. After the lapse of a predetermined holding time, the temperature of the electric furnace was lowered, and the sample was taken out after the temperature inside the electric furnace reached a temperature near room temperature. All of the powders thus obtained were dark green. The starting composition is an atomic ratio of lithium to nickel of 2.05: 0.95 (x = 1/20), 2.14: 0.
Those of 86 (x = 1/7) are referred to as A1a and A1b, respectively. The X-ray diffraction pattern of the A1a powder is shown in FIG.
As an X-ray source, CuK _α from a target Cu enclosure tube
The measurement was performed using a wire at an output of 2 kW. A1a, A1
b, each X-ray diffraction pattern has 2θ = 19.
6 ± 0.5, 25.6 ± 0.5, 44.3 ± 0.5, 4
5.3 ± 0.5, 48.5 ± 0.5, 58.0 ± 0.5
, And the peak intensity ratio of the peaks at 2θ = 25.6 ± 0.5 ° is the strongest intensity, and when normalized to 100, the peak intensity ratio is 2
0-35, 100, 28-35, 18-22, 10-1
It was 4, 17-20. When this diffraction pattern was indexed, it was confirmed that A1a and A1b belong to the space group Immm. Further, from the results of valence analysis of nickel by the iodometry method and elemental analysis by ICP, A1a and A1b are Li _2.05 Ni, respectively.
It was confirmed to be _0.95 O ₂ and Li _2.14 Ni _0.86 O ₂ .

(Embodiment 2) The firing temperature is set to 400 in Embodiment 1.
Samples were prepared using exactly the same procedure except at 0 ° C. Starting composition is 2.0 atomic ratio of lithium and nickel
5: 0.95 (x = 1/20), 2.14: 0.86
Those (x = 1/7) are referred to as A2a and A2b, respectively. All of the powders thus obtained were dark green. The X-ray diffraction pattern of the A2b powder is shown in FIG. The X-ray diffraction measurement was performed under the same conditions as in Example 1. When this diffraction pattern was indexed, A2a, A2
It was confirmed that 2b belongs to the space group Immm. Also, nickel valence analysis and IC by iodometry method
From the result of elemental analysis by P, it was confirmed that A2a and A2b were Li _2.05 Ni _0.95 O ₂ and Li _2.14 Ni _0.86 O ₂ , respectively.

Example 3 A sample was prepared using exactly the same procedure as in Example 1 except that the firing atmosphere was argon gas. The starting composition is an atomic ratio of lithium to nickel of 2.05: 0.95 (x = 1/20), 2.14: 0.
Those of 86 (x = 1/7) are referred to as A3a and A3b, respectively. All of the powders thus obtained were dark green. The X-ray diffraction measurement was performed under the same conditions as in Example 1. When this diffraction pattern was indexed, A
It was confirmed that 3a and A3b belong to the space group Immm. Moreover, from the results of valence analysis of nickel by the iodometry method and elemental analysis by ICP, A3a, A3b
_Are Li _2.05 Ni _0.95 O ₂ and Li _2.14 Ni _0.86 O _{2 respectively.}
Was confirmed.

Example 4 A sample was prepared by using the same procedure as in Example 1 except that Ni (OH) ₂ and Li ₂ O were used as raw materials. The starting composition is an atomic ratio of lithium to nickel of 2.05: 0.95 (x = 1/20), 2.1.
4: 0.86 (x = 1/7) is A4a,
A4b. All of the powders thus obtained were dark green. Indexing this diffraction pattern confirmed that A4a and A4b belonged to the space group Immm. Also, from the results of valence analysis of nickel by the iodometry method and elemental analysis by ICP,
A4a and A4b are Li _2.05 Ni _0.95 O ₂ and Li, respectively.
It was confirmed to be _2.14 Ni _0.86 O ₂ .

(Comparative Example 1) The firing temperature was set to 350 in Example 1.
Samples were prepared using exactly the same procedure except at 0 ° C. Starting composition is 2.0 atomic ratio of lithium and nickel
5: 0.95 (x = 1/20), 2.14: 0.86
Those (x = 1/7) are designated as B1a and B1b, respectively. The X-ray diffraction pattern of B1a is shown in FIG. The X-ray diffraction measurement was performed under the same conditions as in Example 1. From this diffraction pattern, B1a and B1b are both the raw material Li ₂ O.
Was confirmed to be a mixture of NiO and NiO.

(Comparative Example 2) The firing temperature was set to 800 with respect to Example 1.
Samples were prepared using exactly the same procedure except at 0 ° C. Starting composition is 2.0 atomic ratio of lithium and nickel
5: 0.95 (x = 1/20), 2.14: 0.86
Those (x = 1/7) are referred to as B2a and B2b, respectively. The X-ray diffraction measurement was performed under the same conditions as in Example 1. From this diffraction pattern, B2a and B2b are both NiO
It was confirmed to be a mixture of Li ₂ O and Li ₂ O.

Comparative Example 3 A sample was prepared by using exactly the same procedure as in Example 1 except that the firing atmosphere was oxygen gas. The starting composition is the atomic ratio of lithium to nickel 2.
05: 0.95 (x = 1/20), 2.14: 0.86
Those (x = 1/7) are designated as B3a and B3b, respectively. The X-ray diffraction pattern of B3a is shown in FIG. The X-ray diffraction measurement was performed under the same conditions as in Example 1. From this diffraction pattern, both B3a and B3b are rock salt type LiNiO.
It was confirmed to be ₂ .

COMPARATIVE EXAMPLE 4 The starting composition of Example 1 was 1.95: 1.05 (x = -1) in terms of atomic ratio of lithium and nickel.
/ 20), 2.2: 0.8 (x = 1/5), and the sample was prepared using exactly the same procedure. The atomic ratio of lithium to nickel is 1.95: 1.05 (x = -1 /
20) 2.2: 0.8 (x = 1/5) are referred to as B4a and B4b, respectively. The X-ray diffraction patterns of B4a and B4b are shown in FIGS. 8 and 9. The X-ray diffraction measurement was performed under the same conditions as in Example 1. When indexing was performed on this diffraction pattern, it was confirmed that A4a and A4b consisted of substances belonging to the space group Immm and impurities other than them. From this diffraction pattern, B4a is Li ₂ NiO ₂ and N
It was confirmed that iO and B4b were a mixture of Li ₂ NiO ₂ and Li ₂ O.

(Embodiment 5) FIG. 10 is a schematic view of a three-electrode battery which is an embodiment of the present invention. In FIG. 10, 1 is a glass cell, 2 is a lid, 3a, 3b, 3c are all leads, 4
Indicates the opposite pole. Approximately 10 wt% of acetylene black as a conductive agent is mixed with powder obtained by crushing A1a in a mortar, and then approximately 10 wt% of Teflon resin powder is mixed as a binder, and the mixture is pelletized by a tablet molding machine. The molded product was pressed onto a metal mesh to give a positive electrode. For the negative electrode and the counter electrode, a metallic lithium sheet pressure-bonded to a Ni mesh was used. As an electrolyte, 50% by volume of ethylene carbonate-50% by volume of diethyl carbonate and 1 mo
It was used as the LiClO ₄ was dissolved in l / l. These positive electrode, negative electrode and electrolyte were incorporated into a glass cell and a charge / discharge test was conducted. The above work was performed in an Ar dry box.

FIG. 11 shows changes in the potential when the battery thus assembled was charged and discharged at a constant current in the range of 1.5 V to 4.2 V. FIG. 12 shows changes in the capacity with charge / discharge cycles. Is shown in Table 1. 450 mAh on first charge
/ G is charged and discharged about 390mAh / g
That is an extremely large capacity. The capacity of the first charge corresponds to the release of about 1.8 lithium from Li ₂ NiO ₂ and the return of about 1.6 lithium during discharge. Also, it can be seen that the charging / discharging efficiency is very high.

[0049]

[Table 1]

The charge / discharge potential range is from 2.5 V to 4.
FIG. 13 shows the change in potential when the voltage was 2 V, and FIG. 14 and Table 2 show the change in capacity with charge / discharge cycles. A very large capacity of about 320 mAh / g is obtained during the first charge, and the potential is also very flat. This capacity is L
It is shown that about 1.4 lithium atoms were _removed from i _2.14 Ni _0.86 O ₂ . The potential of the discharge gradually dropped, and a discharge capacity of about 140 mAh / g was obtained. No significant change was observed in the capacity even after repeated charging and discharging.

[0051]

[Table 2]

(Example 6) About 1 wt% of acetylene black was mixed as a conductive agent into powder obtained by crushing A1a in a mortar, and then about 50 wt% of Teflon resin powder was mixed as a binder, and this was mixed. A pellet formed by a tablet forming machine was pressed onto a metal mesh to obtain a positive electrode. For the negative electrode and the counter electrode, a metal lithium sheet Ni mesh press-bonded was used. As an electrolyte, 50 vol% propylene carbonate-50 vol% tetrahydrofuran in 1 mo
It was used by dissolving LiPF ₆ in l / l. The positive electrode, the negative electrode, and the electrolyte were incorporated into a glass cell similar to that in Example 5, and a charge / discharge test was conducted. The charge / discharge potential range was 2.5 V to 4.2 V.

Table 3 shows the change in capacity during charging / discharging when charging / discharging was performed at a constant current. It was found that the battery of Example 6 showed almost the same tendency as the battery of Example 5, had a large capacity, and had high charge / discharge efficiency.

[0054]

[Table 3]

(Embodiment 7) FIG. 15 is a schematic view of a coin battery which is an embodiment of the present invention. In FIG. 15, 8 is a positive electrode can, 9 is a positive electrode current collector, 10 is a negative electrode can, 11 is a negative electrode current collector, 12 is packing, and 13 is a separator. Approximately 50 wt% of acetylene black was mixed as a conductive agent with powder obtained by crushing A2a in a mortar, and then approximately 1 wt.
% Teflon resin powder is mixed as a binder, and the mixture is molded into pellets by a tablet molding machine and pressed into a metal mesh to form a positive electrode. Next, the negative electrode is combined with about 1 wt% Teflon resin powder. As a binder, a mixture of graphite powder, pelletized by a tablet molding machine, and pressure bonded to a metal mesh was used. As the electrolyte, a solution prepared by dissolving 0.5 mol / l of LiPF ₆ in 10 vol% propylene carbonate-90 vol% tetrahydrofuran was used. The positive electrode, the negative electrode, and the electrolyte were incorporated into a coin cell, and a charge / discharge test was conducted. The charge / discharge potential range was 2.5 V to 4.2 V. The above work is Ar
It was carried out in a dry box. Table 4 shows the change in capacity during charge and discharge. It was found that the battery of Example 7 also showed a tendency similar to that of the battery of Example 5 and had a large capacity and high charge / discharge efficiency.

[0056]

[Table 4]

Comparative Example 5 A cell was constructed and charged / discharged at a constant current using exactly the same procedure as in Example 5 except that LiNiO ₂ was used for the positive electrode. LiNiO ₂ was obtained by thoroughly mixing LiOH and NiO and firing in an oxygen stream at 750 ° C. for 12 hours. Table 5 shows changes in the charge capacity, discharge capacity and charge / discharge efficiency when the charge / discharge potential range of this cell was changed from 2.5V to 4.2V. As can be seen by comparing Table 2 and Table 5, Li _2.14 Ni _0.86 O in the present invention
_It can be seen that the cell using ₂ has a larger capacity than the cell using the conventional LiNiO ₂ and has good cycle characteristics.

[0058]

[Table 5]

[0059]

According to the present invention, by using Li _{2 + x} Ni _1-x O ₂ (0 <x ≦ 1/7) using nickel, which is an inexpensive material, as the positive electrode, the conventional LiNiO ₂ Compared to this, it has become possible to provide a battery with a larger capacity.

[Brief description of drawings]

FIG. 1 shows Li _2.14 Ni _0.86 O ₂ and Li ₂ N in the present invention.
is a diagram showing an X-ray diffraction pattern of iO _2.

FIG. 2 is a diagram showing a basic structure of Li _2.14 Ni _0.86 O ₂ in the present invention.

FIG. 3 shows Li _2.05 Ni _0.95 O ₂ and Li according to the present invention.
_2.14 is a diagram showing an X-ray diffraction pattern of Ni _0.86 O _2.

FIG. 4 Li _2.05 Ni _0.95 O of Example 1 of the present invention
It is a figure which shows the X-ray-diffraction pattern of ₂ (A1a).

FIG. 5: Li _2.14 Ni _0.86 O of Example 2 of the present invention
It is a figure which shows the X-ray-diffraction pattern of ₂ (A2b).

FIG. 6 is a diagram showing an X-ray diffraction pattern of B1a of Comparative Example 1 in the present invention.

FIG. 7 is a view showing an X-ray diffraction pattern of B3a of Comparative Example 3 in the present invention.

FIG. 8 is a diagram showing an X-ray diffraction pattern of B4a of Comparative Example 4 in the present invention.

FIG. 9 is a diagram showing an X-ray diffraction pattern of B4b of Comparative Example 4 in the present invention.

FIG. 10 is a schematic diagram of a triode battery of Example 5 of the present invention.

FIG. 11 is a diagram showing changes in potential during charge / discharge of A1a according to Example 5 of the present invention.

FIG. 12 is a diagram showing a change in capacity with charge / discharge cycles of A1a of Example 5 of the present invention.

FIG. 13 is a diagram showing changes in potential during charge / discharge of A1a according to Example 5 of the present invention.

FIG. 14 is a diagram showing a change in capacity with charge / discharge cycles of A1a of Example 5 of the present invention.

FIG. 15 is a schematic view of a coin battery of Example 7 of the present invention.

[Explanation of symbols]

 1 glass cell 2 lid 3a lead 3b lead 3c lead 4 counter electrode 5 positive electrode 6 negative electrode 7 electrolyte 8 positive electrode can 9 positive electrode current collector 10 negative electrode can 11 negative electrode current collector 12 packing 13 separator 14 positive electrode 15 negative electrode 16 electrolyte

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01M 10/40 C04B 35/00 J

Claims (14)

[Claims] 1. A composition formula Li _{2 + x} Ni _1-x O ₂ (0.0 <x
A lithium nickel composite oxide represented by ≦ 1/7). 2. Li _{2 + x} Ni _1-x O ₂ (0.0 <x ≦ 1 /
7) shows that planar four-coordinated NiO ₄ sharing the facing sides are connected in a one-dimensional chain, and the planar four-coordinated NiO ₄ one-dimensional chains are positioned in parallel so that the planes of the planar four-coordinated NiO ₄ face each other. The lithium nickel composite oxide according to claim 1, wherein 3. The lithium nickel composite oxide according to claim 1, having a structure belonging to the space group Immm. 4. An X-ray diffraction pattern using CuK _α rays, at least 2θ = 19.6 ± 0.5, 25.6.
± 0.5, 44.3 ± 0.5, 45.3 ± 0.5, 4
The lithium nickel composite oxide according to claim 1, which has peaks in the ranges of 8.5 ± 0.5 and 58.0 ± 0.5, respectively. 5. An X-ray diffraction pattern using CuK _α rays, at least 2θ = 19.6 ± 0.5, 25.6.
± 0.5, 44.3 ± 0.5, 45.3 ± 0.5, 4
It has peaks in the ranges of 8.5 ± 0.5 and 58.0 ± 0.5, and the peak intensity ratio is 2θ = 25.6 ± 0.
When the peak existing at 5 ° is regarded as the strongest intensity and this is standardized as 100, 15-20, 100, 27-
32, 17 to 20, 10 to 13, and 17 to 20. The lithium nickel composite oxide according to claim 1, 2, 3, or 4. 6. Li metal, lithium oxide, lithium peroxide, lithium sulfide, lithium nitride, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium hydroxide, lithium nitrate, lithium carbonate, lithium formate,
Lithium acetate, lithium benzoate, lithium citrate,
At least one lithium raw material selected from the group consisting of lithium lactate, lithium oxalate, lithium pyruvate, lithium stearate, and lithium tartrate, and nickel acetate, nickel amidosulfate, and diammonium nickel (II) sulfate. (Hexahydrate), nickel benzoate, nickel bromide, basic nickel carbonate, nickel carbonyl, nickel chloride, nickel citrate, nickel cyanide, nickel diphosphate, nickel 2-ethylhexanoate, nickel fluoride formic acid. Nickel, nickel hydroxide nickel hypophosphite, nickel iodide, nickel lactate,
Nickel naphthenate, nickel nitrate, nickel oleate, nickel oxalate, nickel monoxide, dinickel trioxide, nickel perchlorate, nickel phosphate, nickel phosphinate, nickel pyrophosphate, nickel stearate, nickel sulfate, nickel sulfide , One or more nickel raw materials selected from the group consisting of nickel tartrate and metallic nickel are mixed so that the molar ratio of lithium to nickel is 2.0: 1.0 to 2.5: 1.0. Li _{2 + x} Ni by firing in an inert gas stream
_A method for producing a lithium-nickel composite oxide, which comprises forming a lithium-nickel composite oxide represented by _{1-xO 2} (0.0 <x ≦ 1/7). 7. The method for producing a lithium-nickel composite oxide according to claim 6, wherein the raw materials are lithium oxide (Li ₂ O) and nickel oxide (NiO). 8. The inert gas is nitrogen, helium, neon,
The method for producing a lithium nickel composite oxide according to claim 6 or 7, wherein the gas is one or more gases selected from the group consisting of argon and krypton. 9. The method for producing a lithium nickel composite oxide according to claim 6, 7, or 8, wherein the firing temperature is 400 to 750 ° C. 10. A positive electrode active material comprising the lithium nickel composite oxide according to any one of claims 1, 2, 3, 4, and 5. 11. A negative electrode comprising a positive electrode containing the lithium nickel composite oxide according to claim 1, as a positive electrode active material, and a lithium metal or a material capable of inserting and extracting lithium. And a non-aqueous secondary battery comprising an ionic conductor. 12. The non-aqueous secondary battery according to claim 11, wherein the negative electrode is a graphite material. 13. The non-aqueous secondary battery according to claim 11, wherein the negative electrode is a carbon material. 14. The non-aqueous secondary battery according to claim 11, wherein the ionic conductor is a non-aqueous electrolyte.