JP2967051B2 - Non-aqueous electrolyte secondary battery and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-aqueous electrolyte secondary battery and a method of manufacturing the same, and more particularly, to a non-aqueous electrolyte secondary battery having a positive electrode containing lithium-containing nickel oxide as an active material and a method of manufacturing the same. It is related to.

[0002]

2. Description of the Related Art In recent years, non-aqueous electrolyte secondary batteries have attracted attention. This is probably because the successful development of a relatively safe negative electrode material and the realization of a high-voltage battery by increasing the decomposition voltage of the non-aqueous electrolyte are thought to be major reasons. Among them, a secondary battery using lithium ions has a particularly high discharge potential, and thus is expected to be a battery having a high energy density.

As a positive electrode active material of a nonaqueous electrolyte secondary battery using lithium ions, manganese spinel (Li
Mn ₂ O ₄ ), lithium-containing cobalt oxide (LiCo
O ₂ ), lithium-containing nickel oxide (LiNiO ₂ )
It has been known. Although the manganese spinel is less expensive than the other two oxides, the positive electrode containing the manganese spinel has a problem that the theoretical capacity is small. The LiCoO ₂ is easier to synthesize than the other two oxides, and the LiCoO ₂
Is excellent in that the theoretical capacity is large.
However, the positive electrode has a problem that the discharge potential is higher than those of the other two oxides, the capacity in a potential range where the nonaqueous electrolyte does not decompose is as low as about half the theoretical capacity, and the price of cobalt is relatively high. There is.

On the other hand, the positive electrode containing LiNiO ₂ has a large theoretical capacity and an optimum discharge potential,
Since the crystal structure of LiNiO ₂ collapses as the charge / discharge cycle progresses, the discharge capacity decreases. In other words, a secondary battery provided with the positive electrode has a short charge-discharge cycle life, and is difficult to commercialize as it is.

[0005] Incidentally, the claims of Japanese Patent Application Laid-Open Publication No. 6-243871 disclose a positive electrode active material in a non-aqueous secondary battery in which a material capable of inserting and extracting lithium ions or metallic lithium is used for the negative electrode. as a composition formula _{Li x Ni 1-y Co y} O w F a ( where, 0 <x ≦ 1.
3,0 ≦ y ≦ 1,1.8 ≦ w + 0.5a ≦ 2.2,0.
25 ≦ a ≦ 2. A non-aqueous secondary battery characterized by using the fluorine-containing composite oxide represented by the formula (1) is disclosed. Further, Examples 1 to 5 of the above publication include:
A disk-shaped positive electrode containing a positive electrode active material, a disk-shaped negative electrode made of metallic lithium, and a flat nonaqueous secondary battery manufactured using a nonaqueous electrolyte, wherein the positive electrode active material LiNiO _1.75 F _0.5 , LiNiO _1.875 F _0.25 , Li
_{NiO 1. 5 F 1, LiNiO 1.25} F 1.5, LiNiO 1
A non-aqueous secondary battery using a fluorine-containing composite oxide represented by F ₂ is described.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a non-aqueous electrolyte secondary battery having improved discharge capacity and charge / discharge cycle life by improving a positive electrode, and a method of manufacturing the same. is there.

[0007]

A non-aqueous electrolyte secondary battery according to the present invention comprises a positive electrode, a negative electrode, and a non-aqueous electrolyte,
The positive electrode includes a lithium-containing nickel oxide represented by a composition formula of Li _{1 + x} Ni _1-x O _uy F _y , wherein x, y, and u satisfy the following formulas (1) to (3). (Y + 0.05) / 2 ≦ x <(y + 1) / 3 (1) y> 0 (2) 1.9 ≦ u ≦ 2.1 (3) Non-water It is an electrolyte secondary battery.

A method for manufacturing a non-aqueous electrolyte secondary battery according to the present invention is a method for manufacturing a non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte. , At least one compound selected from lithium oxide, lithium carbonate and lithium nitrate, at least one compound selected from nickel hydroxide, nickel oxide, nickel carbonate and nickel nitrate, and lithium fluoride And a molar ratio of 0.85 to 1.0: 0.8 to 0.9.
5: mixing at 0.05 to 0.35; maintaining the obtained mixture at 550 to 600 ° C. in an oxygen atmosphere; and firing at 600 to 680 ° C. in an oxygen atmosphere. A method for producing a non-aqueous electrolyte secondary battery, wherein the positive electrode is produced by a method provided.

The non-aqueous electrolyte secondary battery according to the present invention comprises a particle mainly composed of lithium-containing nickel oxide and a film mainly composed of lithium-containing oxide formed on at least a part of the surface of the particle. A positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the lithium-containing nickel oxide has a composition formula represented by Li _{1 + x} Ni _1-x O _uy F _y , wherein the x and y
And u satisfies the following equations (4) to (7): y / 2 ≦ x <(y + 1) / 3 (4) y> 0 (5) x ≧ 0.05 (6) 1.9 ≦ u ≦ 2.1 (7) The lithium-containing oxide has a composition formula of LiMO ₂ (where M is at least selected from Al, Co, Ni, Li, Mn, Ga and Ru). A non-aqueous electrolyte secondary battery.

A method for manufacturing a non-aqueous electrolyte secondary battery according to the present invention is a method for manufacturing a non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, comprising a lithium hydroxide. , At least one compound selected from lithium oxide, lithium carbonate and lithium nitrate, at least one compound selected from nickel hydroxide, nickel oxide, nickel carbonate and nickel nitrate, and lithium fluoride And a molar ratio of 0.85 to 1.0: 0.8 to 0.9.
5: a step of mixing at 0.05 to 0.35; a step of maintaining the obtained mixture at 550 ° C. to 600 ° C. in an oxygen atmosphere; and a step of firing at 600 ° C. to 680 ° C. in an oxygen atmosphere. A step of impregnating the particles with an aqueous solution containing either a lithium nitrate or a lithium organic acid salt and either the element M nitrate or the element M organic acid salt; Are Al, Co,
A step of baking at 500 to 600 ° C. in an oxygen atmosphere at least one selected from Ni, Li, Mn, Ga, and Ru; This is a method for manufacturing a secondary battery.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A non-aqueous electrolyte secondary battery (for example, a cylindrical non-aqueous electrolyte secondary battery) according to the present invention will be described below with reference to FIG.

A bottomed cylindrical container 1 made of, for example, stainless steel has an insulator 2 disposed at the bottom. Electrode group 3
Are stored in the container 1. The electrode group 3 includes:
A belt-like material in which a positive electrode 4, a separator 5 and a negative electrode 6 are laminated in this order is spirally wound so that the separator 5 is located outside. The separator 5
Is formed from, for example, a synthetic resin nonwoven fabric, a polyethylene porous film, or a polypropylene porous film.

The container 1 contains an electrolytic solution. The insulating paper 7 having a central portion opened is placed above the electrode group 3 in the container 1. The insulating sealing plate 8
The sealing plate 8 is disposed at the upper opening of the container 1 and caulked in the vicinity of the upper opening inward.
Is fixed to the container 1 in a liquid-tight manner. The positive terminal 9 is
The insulating sealing plate 8 is fitted at the center. Positive lead
One end of the cathode 10 is connected to the positive electrode 4, and the other end is connected to the positive electrode terminal 9.
Connected to each other. The negative electrode 6 is connected to the container 1 as a negative terminal via a negative lead (not shown).

Next, the configurations of the positive electrode 4, the negative electrode 6, and the non-aqueous electrolyte will be specifically described.

1) Configuration of Positive Electrode 4 The positive electrode 4 has a composition formula of Li _{1 + x} Ni _1-x as an active material.
O _uy F _y , where x, y and u satisfy the following equations (1) to (3): (y + 0.05) / 2 ≦ x <(y + 1) / 3 (1) y> 0 .. (2) 1.9 ≦ u ≦ 2.1 (3) Including a lithium-containing nickel oxide represented by the following formula: This oxide has an α-NaFeO ₂ structure. The atomic ratio of lithium (1 + x) in the above composition formula is a value at the time of oxide synthesis. The amount of lithium in the lithium-containing nickel oxide may increase or decrease as lithium ions are absorbed and released during charge and discharge.

The positive electrode 4 is prepared by, for example, preparing a slurry by mixing particles containing the lithium-containing nickel oxide as a main component, a conductive agent, a binder and a solvent, and applying the slurry to a current collector. After drying, it is produced by pressure molding.

In the lithium-containing nickel oxide, as shown in FIG. 2, x and y are three straight lines x = (y + 0.05) / 2, x = (y + 1) / 3 and y
= 0 (y + 0.05) / 2 ≦ x <
It is possible to take a value in a region satisfying (y + 1) / 3, y> 0. X and y are defined as x <(y + 0.05) /
When the value is within the range satisfying 2 and y> 0, the charge / discharge cycle life may be reduced. On the other hand, when x and y are set to values in a region satisfying x ≧ (y + 1) / 3 and y> 0, the lithium-containing nickel oxide having such a composition has an average valence of nickel component of 4 or more. Therefore, synthesis is impossible in principle.

In the lithium-containing nickel oxide, the value of u is limited to the above range for the following reason. When u is less than 1.9, x
Even if the value of y is in the above range, a part of nickel in the oxide can be divalent, and the charge / discharge efficiency is reduced. On the other hand, when u exceeds 2.1, the charge / discharge efficiency of the battery decreases. This is considered to be due to excess oxygen distorting the crystal lattice and hindering the movement of lithium ions.

A more preferred lithium-containing nickel oxide has a composition formula of Li _{1 + x} Ni _1-x O _{u- y} F _y , wherein u satisfies the above formula (3), and the x and y Satisfy the following expressions (4) and (5).

(Y + 0.05) / 2 ≦ x ≦ (y + 0.2) / 2 (4) 0 <y ≦ 0.4 (5) where x and y are the above formulas (4) to (5). When the expressions are simultaneously satisfied, the x and y are, as shown in FIG. 2 described above, four straight lines x = (y + 0.05) / 2 and x = (y
+0.2) / 2, (y + 0.05) / 2 ≦ x ≦ (y + 0.2) / in the region surrounded by y = 0 and y = 0.4
2, a value within a region satisfying 0 <y ≦ 0.4 can be taken. A non-aqueous electrolyte secondary battery including a positive electrode containing such a lithium-containing nickel oxide can dramatically improve discharge capacity and charge / discharge cycle life.

The lithium-containing nickel oxide may have a composition in which the nickel component is a solid solution of nickel and cobalt or a solid solution of nickel and manganese.

The particles containing the lithium-containing nickel oxide as a main component can be synthesized, for example, by the following method. At least one selected from lithium hydroxide, lithium oxide, lithium carbonate and lithium nitrate
The species, at least one selected from nickel hydroxide, nickel oxide, nickel carbonate and nickel nitrate, and lithium fluoride in a molar ratio of 0.85 to 1.0:
0.8 to 0.95: mixing at 0.05 to 0.35, keeping the resulting mixture at 550 ° C. to 600 ° C. in an oxygen atmosphere, more preferably at 550 ° C. for about 5 hours After that, the particles containing the lithium-containing nickel oxide as a main component are synthesized by firing at 600 ° C. to 680 ° C. for 5 hours or more in an oxygen atmosphere.

The particles containing lithium-containing nickel oxide as a main component include lithium hydroxide, lithium oxide, lithium carbonate, lithium nitrate, nickel hydroxide, nickel oxide, nickel carbonate, nickel nitrate, lithium It is allowed to contain unreacted substances such as fluoride.

In the above synthesis method, if the molar ratio is out of the above range, particles containing lithium-containing nickel oxide as a main component having a composition satisfying the above (1) to (3) may not be obtained. . The molar ratio is 0.95
1.0: 0.9 to 0.95: More preferably, it is 0.05 to 0.15.

The firing temperature is limited to the above range for the following reason. The firing temperature is set at 600
When the temperature is lower than 0 ° C, the time required for sufficiently performing the reaction takes too long, and is not practical. On the other hand, if the firing temperature exceeds 680 ° C., the value of u may decrease to 1.9 or less. A more preferred firing temperature is 6
The range is from 50 ° C to 680 ° C.

Examples of the conductive agent include acetylene black, carbon black, graphite and the like. The conductive agent is used in an oxygen atmosphere at 150 ° C. to 2 ° C.
It is preferable that heat treatment is performed at 50 ° C. for 5 hours or more.

Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyether sulfone (PES), ethylene-propylene-diene copolymer (EPDM), and styrene-butadiene rubber. (SBR) or the like can be used.

As the current collector, for example, an aluminum foil, a stainless steel foil, a nickel foil, or the like is preferably used.

2) Configuration of Negative Electrode 6 As the negative electrode 6, for example, a material made of a substance that absorbs and releases lithium ions (for example, a carbonaceous substance, a chalcogen compound, and a light metal) can be used. Among them, a negative electrode containing a carbonaceous material that occludes and releases lithium ions or a chalcogen compound that occludes and releases lithium ions,
It is preferable because battery characteristics such as cycle life of the secondary battery are improved.

Examples of the carbonaceous material that occludes and releases lithium ions include coke, carbon fiber, pyrolytic gas phase carbon material, graphite, resin fired body, and mesophase pitch carbon. Among the mesophase pitch-based carbons, mesophase pitch-based carbon fibers graphitized at 2500 ° C. or more are preferably mesophase spherical carbons graphitized at 2500 ° C. or more. Such a carbon fiber or a negative electrode containing spherical carbon is preferable because the capacity is increased.

The carbonaceous material is particularly 700 ppm by differential thermal analysis.
It has an exothermic peak above ℃, more preferably above 800 ℃, and has a graphite structure (101)
The intensity ratio P ₁₀₁ / P ₁₀₀ between the diffraction peak (P ₁₀₁ ) and the (100) diffraction peak (P ₁₀₀ ) is preferably in the range of 0.7 to 2.2. Since the negative electrode containing such a carbonaceous material can rapidly store and release lithium ions, the rapid charging and discharging performance of the secondary battery is improved.

The chalcogen compounds that occlude and release lithium ions include titanium disulfide (TiS ₂ ), molybdenum disulfide (MoS ₂ ), and niobium selenide (NbS).
e ₂ ). When such a chalcogen compound is used for the negative electrode, the capacity of the negative electrode increases although the voltage of the secondary battery decreases, so that the capacity of the secondary battery is improved. Further, since the negative electrode has a high diffusion rate of lithium ions, the rapid charge / discharge performance of the secondary battery is improved.

Examples of the light metals that occlude and release lithium ions include aluminum, aluminum alloys, magnesium alloys, lithium metals, and lithium alloys.

For the negative electrode, for example, a slurry is prepared by mixing the carbonaceous material or the chalcogen compound, a binder and a solvent, and applying the slurry to a current collector.
After drying, it is produced by pressure molding.

Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene-propylene-diene copolymer (EPDM), styrene-butadiene rubber (SBR),
Carboxymethyl cellulose (CMC) or the like can be used.

As the current collector, for example, a copper foil, a stainless steel foil, a nickel foil, or the like is preferably used.

3) Structure of Nonaqueous Electrolyte As the nonaqueous electrolyte, a solution in which an electrolyte (lithium salt) is dissolved in a nonaqueous solvent is used.

As the non-aqueous solvent, a known non-aqueous solvent as a solvent for a lithium secondary battery can be used, and is not particularly limited. Ethylene carbonate (EC) has a melting point lower than that of ethylene carbonate and a donor. It is preferable to use a non-aqueous solvent mainly composed of a mixed solvent with one or more non-aqueous solvents having a number of 18 or less (hereinafter, referred to as a second solvent). Such a non-aqueous solvent is advantageous in that it is stable with respect to a negative electrode containing a carbonaceous material having a developed graphite structure, hardly undergoes reductive decomposition or oxidative decomposition of an electrolytic solution, and has high conductivity.

The non-aqueous electrolyte containing ethylene carbonate alone has the advantage of being hardly reductively decomposed to the graphitized carbonaceous material, but has a high melting point (39 ° C. to 40 ° C.).
℃) Because of high viscosity, the conductivity is small and not suitable for a secondary battery operated at room temperature. The second solvent mixed with ethylene carbonate has a lower viscosity than the ethylene carbonate in the mixed solvent to improve conductivity. Further, by using the second solvent having a donor number of 18 or less (provided that the number of donors of ethylene carbonate is 16.4), the ethylene carbonate is not easily solvated selectively with lithium ions, and the graphite structure is developed. It is considered that the reduction reaction of the second solvent with respect to the carbonaceous material is suppressed. Further, by setting the number of donors of the second solvent to 18 or less, the oxidative decomposition potential becomes 4 with respect to the lithium electrode.
V or more, and has an advantage that a high-voltage lithium secondary battery can be realized.

As the second solvent, for example, chain carbon is preferable, and among them, dimethyl carbonate (DM
C), methyl ethyl carbonate (MEC), diethyl carbonate (DEC), or propylene carbonate (PC), γ-butyrolactone (γ-BL), acetonitrile (AN), ethyl acetate (EA), toluene, xylene or methyl acetate (MA) and the like.
These second solvents can be used alone or in the form of a mixture of two or more. In particular, the second solvent more preferably has a donor number of 16.5 or less.

The viscosity of the second solvent is preferably 28 cp or less at 25 ° C. The mixing amount of the ethylene carbonate in the mixed solvent is 1 by volume ratio.
Preferably it is 0-80%. If the ratio is out of this range, the conductivity may be reduced or the solvent may be decomposed, and the charge / discharge efficiency may be reduced. A more preferable blending amount of the ethylene carbonate is 20 to 75% by volume ratio.
By increasing the amount of ethylene carbonate in the non-aqueous solvent to 20% by volume or more, the conductivity of the electrolytic solution is improved.

A more preferred composition of the mixed solvent is EC
And MEC, EC and PC and MEC, EC and MEC and DE
C, EC, MEC, DMC, EC, MEC, PC, DE
In the mixed solvent of C, the volume ratio of MEC is preferably set to 30 to 70%. Thus, the volume ratio of MEC is set to 30.
By setting the content to 70%, more preferably 40% to 60%, the conductivity can be improved. On the other hand, from the viewpoint of suppressing the reductive decomposition reaction of the solvent, using an electrolytic solution in which carbon dioxide (CO ₂ ) is dissolved is effective in improving the capacity and cycle life.

The main impurities present in the mixed solvent (non-aqueous solvent) include water and organic peroxides (eg, glycols, alcohols, carboxylic acids). Each of the impurities may affect the cycle life and the capacity. In addition, self-discharge during high-temperature (60 ° C. or higher) storage may increase. For this reason, it is preferable that the impurities be reduced as much as possible in the electrolytic solution containing the non-aqueous solvent. Specifically, the water content is preferably 50 ppm or less, and the organic peroxide content is preferably 1000 ppm or less.

Examples of the electrolyte contained in the nonaqueous electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), and lithium arsenide hexafluoride (LiBF ₄ ). LiAs
F ₆ ), lithium trifluorometasulfonate (LiC
F ₃ SO ₃ ) and lithium salts (electrolytes) such as lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO ₂ ) ₂ ]. Among them, LiPF ₆ , Li
It is preferable to use BF ₄ or LiN (CF ₃ SO ₂ ) ₂ .

The amount of the electrolyte dissolved in the non-aqueous solvent is desirably 0.5 to 2.0 mol / 1.

In FIG. 1 described above, an example in which the present invention is applied to a cylindrical non-aqueous electrolyte secondary battery which is spirally wound with a separator interposed between a positive electrode and a negative electrode and housed in a cylindrical container having a bottom. However, for example, a separator is interposed between the positive electrode and the negative electrode, the same applies to a square non-aqueous electrolyte secondary battery in which a laminate obtained by laminating a plurality of these is housed in a bottomed rectangular cylindrical container. Can be applied to

The non-aqueous electrolyte secondary battery according to the present invention comprises a particle mainly composed of lithium-containing nickel oxide and a film mainly composed of lithium-containing oxide formed on at least a part of the surface of the particle. A positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the lithium-containing nickel oxide has a composition formula represented by Li _{1 + x} Ni _1-x O _uy F _y , wherein the x and y
And u satisfies the following equations (6) to (9): y / 2 ≦ x <(y + 1) / 3 (6) y> 0 (7) x ≧ 0.05 (8) 1.9 ≦ u ≦ 2.1 (9) The lithium-containing oxide has a composition formula of LiMO ₂ (where M is at least selected from Al, Co, Ni, Li, Mn, Ga and Ru). A non-aqueous electrolyte secondary battery represented by the following formula:

The secondary battery is manufactured by forming an electrode group with a separator interposed between the positive electrode and the negative electrode, storing the electrode group and the non-aqueous electrolyte in a container, and closing the container. Can be manufactured.

As the negative electrode, the separator and the electrolytic solution, the same ones as described above can be used.

(Positive Electrode) This positive electrode contains, as an active material, particles mainly composed of lithium-containing nickel oxide and a film mainly composed of lithium-containing oxide formed on at least a part of the surface of the particles. The lithium-containing nickel oxide has a composition formula of Li _{1 + x} Ni _1-x O _uy F _y , wherein x, y and u simultaneously satisfy the following formulas (6) to (9): y / 2 ≦ x <(y + 1) / 3 (6) 0 <y (7) 0.05 ≦ x (8) 1.9 ≦ u ≦ 2.1 (9) This oxide has an α-NaFeO ₂ structure. The atomic ratio of lithium in the composition formula (1+
x) is a value at the time of oxide synthesis. The amount of lithium in the lithium-containing nickel oxide may increase or decrease as lithium ions are absorbed and released during charge and discharge.

The lithium-containing nickel oxide may have a composition in which the nickel component is a solid solution of nickel and cobalt or a solid solution of nickel and manganese.

The lithium-containing oxide of the film has a composition formula of LiMO ₂ (where M is Al, Co, Ni, Li, M
one, two, or three elements selected from n, Ga, and Ru). Among them, M is A
It is good to be 1, Co, or Mn.

The positive electrode is prepared by, for example, preparing a slurry by mixing particles having the above-described structure, a conductive agent, a binder, and a solvent, applying the slurry to a current collector, drying the slurry, and then pressing it. It is produced by

In the lithium-containing nickel oxide, x and y are four straight lines as shown in FIG. 3, x = y / 2, x = (y + 1) / 3, y = 0, x =
In the region surrounded by 0.05, values in regions other than x = (y + 1) / 3 and y = 0 can be taken. When the value of x and the value of y take a value in a region satisfying x <y / 2 and y> 0, or a value in a region satisfying 0.05> x and y> 0, lithium-containing nickel oxide having such a composition is obtained. In the product, part of the nickel component becomes divalent, and the average valence of the nickel component becomes less than three, so that the charge / discharge cycle life of the secondary battery decreases. Further, x and y are defined as x ≧
When the value is within the range satisfying (y + 1) / 3 and y> 0, the lithium-containing nickel oxide having such a composition has an average valence of nickel component of 4 or more, and cannot be synthesized in principle. It is.

In the lithium-containing nickel oxide, the value of u is limited to the above range for the following reason. When u is less than 1.9, x
Even if the value of y is in the above range, a part of nickel in the oxide can be divalent, and the charge / discharge efficiency is reduced. On the other hand, when u exceeds 2.1, the charge / discharge efficiency of the battery decreases. This is considered to be because excess oxygen distorts the crystal lattice and hinders the movement of lithium ions.

More preferable lithium-containing nickel oxide has a composition formula of Li _{1 + x} Ni _1-x O _{u- y} F _y , wherein u satisfies the above-mentioned formula (9), and the above-mentioned x and y Satisfy the following (8), (10), and (11) at the same time.

0.05 ≦ x (8) (y + 0.05) / 2 ≦ x ≦ (y + 0.2) / 2 (10) 0 <y ≦ 0.4 (11) The x and the y are Equations (8), (10) and (1)
When the expression (1) is satisfied at the same time, the x and the y are expressed by five straight lines x = (y + 0.0) as shown in FIG.
5) / 2, x = (y + 0.2) / 2, y = 0, y = 0.
Among the regions surrounded by 4 and x = 0.05, values within the region excluding y = 0 can be taken. A non-aqueous electrolyte secondary battery including a positive electrode including particles mainly composed of a lithium-containing nickel oxide having such a composition and having at least a part of the surface thereof coated with the film has an initial capacity of In addition, the charge / discharge cycle life can be significantly improved.

The film may be formed on at least a part of the surface of the particles containing the lithium-containing nickel oxide as a main component. A preferred particle morphology is one in which the entire surface is coated with the film.

The film is preferably formed by epitaxial growth on the surface of a particle containing the lithium-containing nickel oxide as a main component. Here, the epitaxial growth means that the lithium-containing oxide crystal grows on the surface of the lithium-containing nickel oxide crystal (base crystal) such that at least the direction of the c-axis is the same as the direction of the c-axis of the base crystal. I do. Lithium ions are absorbed and released into the lithium-containing nickel oxide crystal and the lithium-containing oxide crystal along a direction perpendicular to the c-axis of these crystals. Therefore, the film mainly composed of the lithium-containing oxide formed by the epitaxial growth has the same direction as the particles mainly composed of the lithium-containing nickel oxide in which the lithium ions are inserted and extracted. The particles formed on the surface can smoothly occlude and release lithium ions, and can avoid an increase in internal impedance at the time of storing and releasing lithium ions due to film formation.

The thickness of the film is preferably in the range of 1 nm to 50 nm. This is due to the following reasons. When the thickness of the film is less than 1 nm, it is difficult to suppress or avoid the reaction between the fluorine component of the lithium-containing nickel oxide and the conductive agent or the electrolytic solution of the positive electrode. There is a risk that improvement may be difficult. On the other hand, the thickness of the film is 50 n
If it exceeds m, the lithium-containing oxide crystal cannot sufficiently follow the change in the lattice constant of the lithium-containing nickel oxide crystal due to the occlusion and release of lithium ions, so that distortion occurs at the contact interface between the film and the particles. And the film may peel off from the lithium-containing nickel oxide particles. In addition, the ratio of the lithium-containing nickel oxide in the positive electrode may be insufficient, and the capacity of the positive electrode may be reduced. More preferred film thickness is 10 nm to 30 n
m.

The lithium-containing nickel oxide (Li _{1 + x} Ni _1-x O) whose surface is at least partially covered with a film containing the lithium-containing oxide (LiMO ₂ ) as a main component.
_uy F _y) particles composed mainly of, for example, can be prepared by methods described below.

First, at least one selected from lithium hydroxide, lithium oxide, lithium carbonate and lithium nitrate, and nickel hydroxide, nickel oxide,
A molar ratio of at least one selected from nickel carbonate and nickel nitrate to lithium fluoride is 0.85 to 0.85.
1.0: 0.8 to 0.95: 0.05 to 0.35, and the resulting mixture is heated to 550 ° C to 60 ° C in an oxygen atmosphere.
After maintaining at 0 ° C., more preferably at 550 ° C. for about 5 hours, and then in an oxygen atmosphere at 600 ° C. to 680 ° C.
(6) to (9)
Particles mainly composed of lithium-containing nickel oxide having a composition satisfying the formula are synthesized.

As a lithium source, lithium nitrate or a lithium organic acid salt (for example, lithium acetate) and an element M (M is Al, Co, Ni, Li, Mn, Ga and Ru)
A nitrate of the element M or an organic acid salt of the element M (for example, acetate) is dissolved in distilled water at a molar ratio of 1: 1 to prepare a film-forming solution. . After impregnating the particles with the obtained solution,
By baking at 500 ° C. to 600 ° C. for 5 hours or more in an oxygen atmosphere, at least a part of the particle surface has a composition formula of LiMO ₂ (M is Al, Co, Ni, Li, Mn, Ga
And at least one selected from Ru) are formed by epitaxial growth. The amount of the solution for impregnating the particles is preferably such that the molar ratio of the lithium-containing oxide film formed to the particles is 2% or less.
By such a method, particles containing the lithium-containing nickel oxide as a main component, at least a part of the surface of which is coated with the lithium-containing oxide film, are produced.

The firing temperature in the film forming step is limited to the above range for the following reason. If the calcination temperature is lower than 500 ° C., the time required for the film formation reaction takes too long, and the mass productivity may be reduced. On the other hand, if the calcination temperature exceeds 600 ° C., the film-forming solution and the particles cause mutual diffusion and are mixed, and the film may not be formed on the surface of the particles. A more preferred firing temperature is in the range of 530C to 580C.

The particles containing lithium-containing nickel oxide as a main component include lithium hydroxide, lithium oxide, lithium carbonate, lithium nitrate, nickel hydroxide, nickel oxide, nickel carbonate, nickel nitrate. , And unreacted substances such as lithium fluoride.

The film containing the lithium-containing oxide as a main component is made of a lithium nitrate, a lithium organic acid salt, and an element M (M is Al, Co, Ni, Li, Mn, Ga, and Ru).
And at least one unreacted substance such as an organic acid salt of the element M.

As the conductive agent, the binder and the current collector, the same ones as described above can be used.

As described above, the nonaqueous electrolyte secondary battery according to the present invention has a composition formula of Li _{1 + x} Ni _1-x O
_uy F _y , where x, y and u satisfy the following equations (1) to (3): (y + 0.05) / 2 ≦ x <(y + 1) / 3 (1) y> 0 (2) 1.9 ≦ u ≦ 2.1 (3) A positive electrode containing a lithium-containing nickel oxide represented by the following formula (3) is provided. Such a secondary battery can improve discharge capacity (initial capacity) and charge / discharge cycle life. It is not clear why the nonaqueous electrolyte secondary battery according to the present invention can achieve high capacity and long life, but it is presumed to be due to the following mechanism.

In the nonaqueous electrolyte secondary battery provided with the positive electrode containing LiNiO ₂ as an active material, the collapse of the crystal structure of LiNiO ₂ accompanying the progress of the charge / discharge cycle is caused by the following explanation. Likely to occur.

The nickel component of LiNiO ₂ tends to have two valences. Since the radius of divalent nickel is substantially equal to that of lithium ions, the presence of divalent nickel is mixed into the lithium sites of LiNiO ₂ . The divalent nickel mixed into the lithium site hinders the lithium ions moving through the LiNiO ₂ during charging and discharging.
The internal impedance when moving O ₂ increases. As a result, since the over-voltage and the internal stress applied to the LiNiO ₂ is increased, the crystal structure of LiNiO ₂ collapses with the progress of charge and discharge cycles.

The LiNiO ₂ undergoes a structural phase transition when lithium ions are absorbed and released, which causes the collapse of the crystal structure. The structural phase transition is defined by Jahn-Tel
A mechanism based on the ler effect has been proposed. That is, in LiNiO ₂ , when lithium ions are occluded in all the lithium sites, the valence of nickel existing in the nickel sites is trivalent. On the other hand, when lithium ions are released from all the lithium sites, the valence of nickel existing at the nickel sites becomes tetravalent. Trivalent nickel tends to be distorted from a spherical shape due to the Jahn-Teller effect. In the state where lithium ions are occluded in all lithium sites of LiNiO ₂ , 3
Valent nickel is regulated in spherical shape by this lithium ion. When lithium ions are released, Li
Since a gap is formed in NiO ₂ , that is, the regulation by lithium ions is released, the distortion of trivalent nickel increases. As a result, the LiNiO ₂ is distorted as lithium ions are released therefrom. This distortion is eliminated when nickel becomes tetravalent by releasing lithium ions from all lithium sites of the LiNiO ₂ and the Jahn-Teller effect becomes small. Therefore, when lithium ions are repeatedly inserted into and released from LiNiO ₂ , this structural phase transition is repeatedly performed, so that LiNiO ₂ becomes brittle and the crystal structure is collapsed.

In such LiNiO ₂ , when a part of oxygen atoms is replaced by fluorine atoms, for example, the composition formula Li
_x NiO _w F _a (where 0 <x ≦ 1.3, 1.8 ≦ w +
0.5a ≦ 2.2, 0.25 ≦ a ≦ 2. ) Is obtained. In the fluorine-containing composite oxide, the total valency of the anions is smaller than the total valency of the anions of LiNiO _{2 because} a part of the oxygen atoms is replaced by fluorine atoms. The fluorine-containing composite oxide has an atomic ratio of lithium and nickel of Li
Since it is the same as that of NiO ₂ , such a decrease in the positive charge accompanying the decrease in the negative charge is made by a decrease in the valence of the nickel component from trivalent to divalent.

For this reason, the fluorine-containing composite oxide is
The proportion of divalent nickel in the nickel component increases, and the internal impedance at the time of inserting and extracting lithium ions increases. Moreover, since the average valence of the nickel component of the fluorine-containing composite oxide is less than 3, the degree of distortion due to the Jahn-Teller effect of nickel existing at nickel sites when lithium ions are released is increased. As a result, the non-aqueous secondary battery including the positive electrode including the fluorine-containing composite oxide as an active material has a reduced charge / discharge cycle life because the crystal structure of the oxide collapses with progress of charge / discharge. .

The composition formula Li _{1 + x} Ni _1-x O according to the present invention
_The lithium-containing nickel oxide represented by _uy F _y is L
A part of the oxygen atom of iNiO ₂ is replaced with a fluorine atom, and the reduction of the total valency of the cation corresponding to the reduction of the total valency of the anion caused by this substitution is performed by replacing a part of the nickel atom with a lithium atom. Since the substitution is performed, the proportion of divalent nickel in the nickel component can be significantly reduced, and the average valence of the nickel component can be increased to three or more. As a result, the lithium-containing nickel oxide can suppress an increase in internal impedance at the time of lithium ion occlusion and release caused by mixing of divalent nickel into the lithium site, and simultaneously release lithium ions. In this case, the nickel Jahn-Tell existing at the nickel site
The distortion due to the er effect can be suppressed. Further, since fluorine has a higher electronegativity than oxygen, the Coulomb force between fluorine and lithium is weaker than the Coulomb force between oxygen and lithium. For this reason, the lithium-containing nickel oxide can reduce the interaction (Coulomb force) with lithium ions by the fluorine component of the oxide, and reduce the internal impedance when lithium ions move (occlusion / release). Can be reduced.

Accordingly, the nonaqueous electrolyte secondary battery provided with the positive electrode containing the lithium-containing nickel oxide as an active material can suppress or avoid the collapse of the oxide crystal structure accompanying the progress of the charge / discharge cycle. Therefore, the discharge capacity (initial capacity) and the charge / discharge cycle life can be improved.

The method for manufacturing a non-aqueous electrolyte secondary battery according to the present invention is a method for manufacturing a non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, comprising a lithium hydroxide. , At least one compound selected from lithium oxide, lithium carbonate and lithium nitrate, at least one compound selected from nickel hydroxide, nickel oxide, nickel carbonate and nickel nitrate, and lithium fluoride And a molar ratio of 0.85 to 1.0: 0.8 to 0.9.
5: mixing at 0.05 to 0.35; maintaining the obtained mixture at 550 to 600 ° C. in an oxygen atmosphere; and firing at 600 to 680 ° C. in an oxygen atmosphere. The positive electrode is manufactured by the provided method. According to such a method, a non-aqueous electrolyte secondary battery including a positive electrode including particles containing lithium-containing nickel oxide as a main component represented by the above-described composition formula can be manufactured.
A nonaqueous electrolyte secondary battery with improved discharge capacity (initial capacity) and charge / discharge cycle life can be provided.

Another non-aqueous electrolyte secondary battery according to the present invention mainly comprises particles containing lithium-containing nickel oxide as a main component and a lithium-containing oxide formed on at least a part of the surface of the particles. A positive electrode including a film as a component, a negative electrode, and a non-aqueous electrolyte are provided. The lithium-containing nickel oxide has a composition formula of Li _{1 + x} Ni _1-x O _uy F _y ,
X, y, and u satisfy the following equations (4) to (7): y / 2 ≦ x <(y + 1) / 3 (4) 0 <y (5) 0.05 ≦ x ( 6) 1.9 ≦ u ≦ 2.1 (7) Further, the lithium-containing oxide has a composition formula of LiMO ₂ (where M is Al, Co, Ni, Li,
And at least one element selected from Mn, Ga and Ru).

In such a secondary battery, the discharge capacity (initial capacity) and the charge / discharge cycle life can be significantly improved. It is not clear why the secondary battery according to the present invention can achieve high capacity and long life, but it is presumed to be due to the mechanism described below.

The lithium-containing nickel oxide represented by the composition formula Li _{1 + x} Ni _1-x O _uy F _y has a structure in which a part of oxygen atoms are replaced by fluorine atoms, and a reduction in negative charges caused by the replacement is _achieved. The proportionate reduction in positive charge is achieved by substituting some of the nickel atoms with lithium atoms, so that the proportion of divalent nickel in the nickel component can be significantly reduced. As a result, the particles containing the lithium-containing nickel oxide as a main component can suppress an increase in internal impedance at the time of lithium ion occlusion and release caused by mixing of divalent nickel into the lithium site, and at the same time, When lithium ions are released, Jah of nickel existing at nickel sites
Distortion due to the n-Teller effect can be suppressed. In addition, the particles containing the lithium-containing nickel oxide as a main component can reduce the interaction with lithium ions due to the fluorine component, and thus reduce the internal impedance at the time of insertion and extraction of lithium ions due to the interaction. Can be reduced.

Further, in the film mainly composed of a lithium-containing oxide formed on at least a part of the surface of the particles, the fluorine component in the particles is a component of a battery (for example, a conductive agent in the positive electrode, (A non-aqueous electrolyte) can be suppressed or avoided, that is, a decrease in positive charge accompanying a decrease in negative charge caused by this reaction, that is, a valence of the nickel component changes from trivalent to divalent Can be suppressed or avoided. For this reason, the above-mentioned oxide film forming particles can suppress or avoid an increase in the proportion of divalent nickel in the nickel component of the lithium-containing nickel oxide as the charge-discharge cycle progresses.

Therefore, a non-aqueous electrolyte secondary battery provided with a positive electrode containing particles mainly composed of lithium-containing nickel oxide and having a film mainly composed of lithium-containing oxide formed on at least a part of the surface thereof is Since the ratio of divalent nickel in the nickel component of the lithium-containing nickel oxide can be maintained at a low value over a long period of time, the collapse of the crystal structure of the lithium-containing nickel oxide due to the progress of the charge / discharge cycle is suppressed. In addition, the discharge capacity (initial capacity) and the charge / discharge cycle life can be significantly improved.

Further, by forming a film mainly composed of a lithium-containing oxide by epitaxial growth on at least a part of the surface of the particle mainly composed of the lithium-containing nickel oxide, lithium in the oxide of the particle is obtained. Since the direction in which ions are inserted and released and the direction in which lithium ions in the lithium-containing oxide of the film are inserted and released can be made to match, the particles are able to smoothly and promptly disperse lithium ions as in the case of non-film-formed particles. Can be inserted and released. Therefore, a nonaqueous electrolyte secondary battery including a positive electrode containing such particles as an active material can further improve the discharge capacity (initial capacity) and the charge / discharge cycle life.

Further, by setting the thickness of the film formed on at least a part of the surface of the particles containing the lithium-containing nickel oxide as a main component to be in the range of 1 nm to 50 nm, the charge-discharge cycle is progressed. The peeling of the film can be suppressed or avoided, and the film prevents the fluorine component of the lithium-containing nickel oxide from reacting with a battery component (for example, the conductive agent in the positive electrode, the non-aqueous electrolyte). It can be suppressed or avoided, and at the same time, the capacity of the positive electrode can be maintained at a high value. Therefore, a non-aqueous electrolyte secondary battery provided with a positive electrode containing such particles as an active material,
The discharge capacity (initial capacity) and the charge / discharge cycle life can be further improved.

The method of manufacturing a non-aqueous electrolyte secondary battery according to the present invention is a method of manufacturing a non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte. At least one compound selected from an oxide, lithium oxide, lithium carbonate and lithium nitrate, at least one compound selected from nickel hydroxide, nickel oxide, nickel carbonate and nickel nitrate, and lithium The molar ratio of fluoride to 0.85 to 1.0: 0.8 to
0.95: a step of mixing at 0.05 to 0.35; a step of maintaining the obtained mixture at 550 ° C. to 600 ° C. in an oxygen atmosphere; firing at 600 ° C. to 680 ° C. in an oxygen atmosphere. Producing particles by the following method: either lithium nitrate or lithium organic acid salt and the element M
Impregnating the particles with an aqueous solution containing either a nitrate or an organic acid salt of element M, wherein M is A
1, at least one member selected from the group consisting of Co, Ni, Li, Mn, Ga, and Ru;
Baking at 00 ° C. to produce the positive electrode. According to such a method, the lithium-containing nickel oxide represented by the above-described composition formula as a main component,
Since it is possible to manufacture a nonaqueous electrolyte secondary battery including a positive electrode including particles in which a film containing a lithium-containing oxide having the above composition as a main component is formed on at least a part of the surface, the discharge capacity (initial capacity) ) And a non-aqueous electrolyte secondary battery with significantly improved charge / discharge cycle life can be provided.

[0085]

Embodiments of the present invention will be described below in detail with reference to the drawings. It should be noted that the present invention is not limited to the following embodiments at all, and can be implemented with appropriate changes within a scope that does not change the gist of the present invention.

The composition formula of the lithium-containing nickel oxide used as the positive electrode active material in the following Examples 1 to 9, 37, 39 and 48 is shown in Table 1 below. FIG. 4 shows the distribution of the composition of these oxides.

[0087]

[Table 1]

Example 1 <Preparation of Positive Electrode> LiOH.H ₂ O, Ni (OH) ₂ and L
iF was mixed at a molar ratio of 1.0: 0.95: 0.05, and kept at 550 ° C. for 5 hours in 1 atm of pure water oxygen.
And crushed in an agate mortar to produce particles containing lithium-containing nickel oxide as a main component represented by a composition formula of Li _1.05 Ni _0.95 O _1.96 F _0.04 . The average particle size of the obtained particles was 8.5 μm. The obtained particles, acetylene black as a conductive agent, and polytetrafluoroethylene powder as a binder were mixed at a weight ratio of 80: 17: 3 to prepare a positive electrode mixture. Affixing the positive electrode mixture to a stainless steel net as a current collector,
A positive electrode of 0 mm square × 0.5 mm was produced.

<Preparation of Negative Electrode> A lithium metal foil was attached to a stainless steel net as a current collector to prepare a 20 mm square negative electrode.

<Preparation of Reference Electrode> A 10 mm square reference electrode was prepared by attaching a lithium metal foil to a stainless steel net as a current collector.

<Preparation of Nonaqueous Electrolyte> A nonaqueous electrolyte was prepared by dissolving LiClO ₄ as an electrolyte at a concentration of 1 mol / l in a mixed solvent composed of propylene carbonate and dimethoxyethane.

<Preparation of Battery for Positive Electrode Evaluation>
After thoroughly drying the negative electrode, reference electrode and non-aqueous electrolyte,
Using these members in an argon atmosphere, an evaluation battery provided with a beaker-type glass cell shown in FIG. 5 was assembled.

That is, the non-aqueous electrolyte 22 is accommodated in the glass cell 21. The positive electrode 23 and the negative electrode 24 housed in the bag-shaped separator are stacked with a separator 25 interposed therebetween, and immersed in the electrolytic solution 22 in the glass cell 21. The two holding plates 26 sandwich the laminate between them. The reference electrode 27 accommodated in the bag-shaped separator is immersed in the electrolytic solution 22 in the glass cell 21. 3 glass filters 2
8 has one end protruding outside through the upper surface of the glass cell 21 and the other end connected to the positive electrode 23, the negative electrode 24, and the reference electrode 27, respectively. Such a glass cell 21 is subjected to a sealing treatment so that the atmosphere does not enter during the charge / discharge test.

Example 2 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.98: 0.9: 0.12, and the mixture was heated to 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After being held and calcined at 650 ° C. for 20 hours, the mixture is pulverized in an agate mortar, whereby the composition formula becomes L.
A positive electrode was produced in the same manner as in Example 1, except that lithium-containing nickel oxide represented by i _1.1 Ni _0.9 O _1.9 F _0.1 was used as a main component and particles having an average particle size of 8.5 μm were synthesized. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 3 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.98: 0.85: 0.17, and the mixture was heated to 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After being held and calcined at 650 ° C. for 20 hours, the mixture is pulverized in an agate mortar to make a lithium-containing nickel oxide represented by a composition formula of Li _1.15 Ni _0.85 O _1.85 F _0.15 as a main component and an average particle size of 8. A positive electrode similar to that of Example 1 was prepared except that particles of 5 μm were synthesized. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 4 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 1.14: 0.8: 0.06, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After being held and calcined at 650 ° C. for 20 hours, the mixture is pulverized in an agate mortar, whereby the composition formula becomes L.
A positive electrode was produced in the same manner as in Example 1 except that lithium-containing nickel oxide represented by i _1.2 Ni _0.8 O _1.95 F _0.05 was used as a main component and particles having an average particle size of 8.5 μm were synthesized. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 5 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 0.95: 0.8: 0.25, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After being held and calcined at 650 ° C. for 20 hours, the mixture is pulverized in an agate mortar, whereby the composition formula becomes L.
A positive electrode was produced in the same manner as in Example 1, except that lithium-containing nickel oxide represented by i _1.2 Ni _0.8 O _1.8 F _0.2 was used as a main component and particles having an average particle size of 8.5 μm were synthesized. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 6 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.8: 0.8: 0.4, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water oxygen. After being held and calcined at 650 ° C. for 20 hours, the composition formula is Li by grinding in an agate mortar.
A positive electrode similar to that of Example 1 was produced, except that lithium-containing nickel oxide represented by _1.2 Ni _0.8 O _1.65 F _0.35 was used as a main component and particles having an average particle size of 8.5 μm were synthesized. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 7 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 1.0: 0.85: 0.15, and the mixture was heated to 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After being held and calcined at 650 ° C. for 20 hours, the mixture is pulverized in an agate mortar, whereby the composition formula becomes L.
A positive electrode was produced in the same manner as in Example 1 except that lithium-containing nickel oxide represented by i _1.15 Ni _0.85 O _1.85 F _0.12 was mainly used and particles having an average particle diameter of 8.5 μm were synthesized. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 8 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 1.0: 0.9: 0.1, and the mixture was heated to 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After being held and calcined at 650 ° C. for 20 hours, the composition formula is Li by grinding in an agate mortar.
A positive electrode similar to that of Example 1 was produced except that particles containing lithium nickel oxide represented by _1.1 Ni _0.9 O _1.92 F _0.09 as a main component and having an average particle diameter of 8.5 μm were synthesized. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 9 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 1.0: 0.8: 0.2, and the mixture was heated to 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After being held and calcined at 650 ° C. for 20 hours, the composition formula is Li by grinding in an agate mortar.
A positive electrode similar to that of Example 1 was produced, except that particles containing lithium-containing nickel oxide represented by _1.2 Ni _0.8 O _1.77 F _0.19 as a main component and having an average particle diameter of 8.5 μm were synthesized. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 1 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 0.83: 1.0: 0.17, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After being held and calcined at 650 ° C. for 20 hours, the mixture is pulverized in an agate mortar, whereby the composition formula becomes L.
The lithium-containing nickel oxide represented by iNiO _1.85 F _{0. 15} as a main component, the average particle size except to synthesize particles of 8.5 .mu.m, was produced in the same manner as positive electrode as in Example 1. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 2 LiOH.H ₂ O and Ni (OH) ₂ in a molar ratio of 1.02
5: 0.975 and mixed in pure water at 1 atm.
° C. To 5 hours, after firing at 650 ° C. 20 hours, the composition formula by grinding in an agate mortar Li _1.025 Ni
A positive electrode was produced in the same manner as in Example 1, except that lithium-containing nickel oxide represented by _0.975 O ₂ was a main component and particles having an average particle size of 8.5 μm were synthesized. Using the positive electrode, the negative electrode, the reference electrode, and the non-aqueous electrolyte similar to those in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 3 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.85: 0.95: 0.2, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After being held and calcined at 650 ° C. for 20 hours, the mixture is pulverized in an agate mortar, whereby the composition formula becomes L.
A positive electrode similar to that of Example 1 was produced except that lithium-containing nickel oxide represented by i _1.05 Ni _0.95 O _1.83 F _0.17 was mainly used and particles having an average particle size of 8.5 μm were synthesized. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 4 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.85: 0.9: 0.25, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After being held and calcined at 650 ° C. for 20 hours, the mixture is pulverized in an agate mortar, whereby the composition formula becomes L.
A positive electrode similar to that of Example 1 was produced except that lithium-containing nickel oxide represented by i _1.1 Ni _0.9 O _1.79 F _0.21 was mainly used and particles having an average particle size of 8.5 μm were synthesized. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 5 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 0.75: 0.9: 0.35, and the mixture was heated to 550 ° C. for 5 hours in one atmosphere of pure water oxygen. After being held and calcined at 650 ° C. for 20 hours, the mixture is pulverized in an agate mortar, whereby the composition formula becomes L.
A positive electrode similar to that of Example 1 was produced except that lithium-containing nickel oxide represented by i _1.1 Ni _0.9 O _1.7 F _0.3 was used as a main component and particles having an average particle size of 8.5 μm were synthesized. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 6 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.75: 0.85: 0.4, and the mixture was heated to 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After being held and calcined at 650 ° C. for 20 hours, the mixture is pulverized in an agate mortar, whereby the composition formula becomes L.
A positive electrode was produced in the same manner as in Example 1 except that lithium-containing nickel oxide represented by i _1.15 Ni _0.85 O _1.62 F _0.38 was used as a main component and particles having an average particle size of 8.5 μm were synthesized. Using the positive electrode, the negative electrode, the reference electrode, and the non-aqueous electrolyte similar to those in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 7 The molar ratio of LiOH.H ₂ O to Ni (OH) ₂ was 1.1.
5: 0.85, 550 ° C. in 1 atm of pure water oxygen
And calcined at 650 ° C. for 20 hours, and then pulverized in an agate mortar to obtain a composition formula of Li _1.15 Ni _0.85
A positive electrode was produced in the same manner as in Example 1, except that lithium-containing nickel oxide represented by O ₂ was a main component and particles having an average particle size of 8.5 μm were synthesized. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 8 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 0.8: 0.85: 0.35, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After being held and calcined at 650 ° C. for 20 hours, the mixture is pulverized in an agate mortar, whereby the composition formula becomes L.
A positive electrode was produced in the same manner as in Example 1 except that lithium-containing nickel oxide represented by i _1.15 Ni _0.85 O _1.7 F _0.3 was used as a main component and particles having an average particle size of 8.5 μm were synthesized. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

The batteries of Examples 1 to 9 and Comparative Examples 1 to 8 were charged until the current reached 4.2 V at a current value of 1 mA.
The current was stopped for 0 minutes, and then the discharge was performed at a current value of 1 mA for 3.0 minutes.
The cycle is repeated until the voltage reaches V, and the current is stopped again for 30 minutes. Changes in the discharge capacity according to the number of cycles are measured, and the initial charge capacity and the discharge capacity at the 100th cycle are shown in Table 2 below.

[0111]

[Table 2]

As is clear from Table 2, the batteries of Examples 1 to 9 have better cycle life than the batteries of Comparative Examples 1 to 8. As can be seen from Table 1 and FIG. 5, in the batteries of Examples 1 to 9, the composition formula Li _{1 + x} Ni _1-x O _uy F _y as the positive electrode active material, x, y, and u were used. (Y + 0.05) / 2 ≦ x <(y + 1) / 3 (1) y> 0 (2) 1.9 ≦ u ≦ 2.1 ((1) to (3)) 3) This is because a lithium-containing nickel oxide represented by the following formula was used.

On the other hand, the short cycle life of the batteries of Comparative Examples 1 to 8 is apparent from Table 1 and FIG.
This is because, as the positive electrode active material, a lithium-containing composite oxide having a composition outside the range satisfying the above formulas (1) to (3) was used.

Further, after charging the batteries of Example 1 and Comparative Example 2 until the voltage reached 4.2 V at a current value of 1 mA, the current was stopped for 30 minutes, and then discharging was performed at a current value of 3.0 mA at a current value of 1 mA. , The cycle of stopping the current again for 30 minutes is repeated, and the discharge capacity up to the 30th cycle is measured. The result is shown in FIG.

As is apparent from FIG. 6, the battery of Example 1 provided with the positive electrode containing the lithium-containing nickel oxide represented by the above-described composition formula Li _{1 + x} Ni _1-x O _Uy F _y has a capacity of 3
It can be seen that high capacity can be maintained over 0 cycles. In contrast, the battery of Comparative Example 2 had a higher initial capacity than that of Example 1, but had a discharge capacity at the 30th cycle of Example 1.
It turns out that it is low compared with. This is because using the Li _1.025 Ni _0.975 O ₂ as the positive electrode active material.

The composition formula of the lithium-containing nickel oxide used as the positive electrode active material in the following examples is shown in Table 3 below.
Shown in FIG. 7 shows the distribution of the composition of these oxides.

[0117]

[Table 3]

Example 10 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 1.0: 0.95: 0.05, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, the mixture was baked at 650 ° C. for 20 hours, and crushed in an agate mortar, whereby the composition formula was L.
Particles mainly composed of lithium-containing nickel oxide represented by i _1.05 Ni _0.95 O _1.96 F _0.04 were produced. The average particle size of the obtained particles was 8.5 μm. On the other hand, a 1 mol / l mixed aqueous solution composed of lithium nitrate and cobalt nitrate was prepared. The molar ratio of lithium and cobalt contained in the mixed aqueous solution was 1: 1. 5 mol of the mixed aqueous solution was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles.
By baking at 0 ° C. for 20 hours, a film (thickness: 20 nm) containing LiCoO ₂ as a main component was formed on the entire surface of the particles by epitaxial growth. LiC of the film
oO ₂ has a c-axis orientation of the above Li _1.05 Ni _0.95 O _1.96 F
It had the same crystal structure as the c-axis orientation of _0.04 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 11 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.98: 0.9: 0.12, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, the mixture was baked at 650 ° C. for 20 hours, and crushed in an agate mortar, whereby the composition formula was L.
Particles mainly composed of lithium-containing nickel oxide represented by i _1.1 Ni _0.9 O _1.9 F _0.1 were produced. The average particle size of the obtained particles was 8.5 μm. 5 mol of a mixed aqueous solution having the same composition as in Example 10 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in 1 atm of pure water oxygen. L is epitaxially grown on the entire surface of the particles.
A film (thickness: 20 nm) containing iCoO ₂ as a main component was formed. LiCoO ₂ of the film has a c-axis direction of Li
It had a crystal structure that was the same as the direction of the c-axis of _1.1 Ni _0.9 O _1.9 F _0.1 .

A positive electrode was produced in the same manner as in Example 1 except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 12 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.9: 0.9: 0.2, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, baked at 650 ° C. for 20 hours and pulverized in an agate mortar, whereby the composition formula is Li
Particles mainly composed of lithium-containing nickel oxide represented by _1.1 Ni _0.9 O _1.83 F _0.17 were produced. The average particle size of the obtained particles was 8.5 μm. 5 cc of a mixed aqueous solution having the same composition as in Example 10 was added to 1 mol of the particles,
After the solution is sufficiently impregnated into the particles, the particles are calcined at 550 ° C. for 20 hours in 1 atm of pure water and oxygen, and Li is epitaxially grown on the entire surface of the particles by Li.
A film (thickness: 20 nm) containing CoO ₂ as a main component was formed. LiCoO ₂ of the film has a c-axis orientation of the Li _1.
1 Ni _0.9 O _1.83 F _{0.17 had} the same crystal structure as the direction of the c-axis.

A positive electrode was prepared in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 13 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.98: 0.85: 0.17, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, 20 minutes at 650 ° C
The particles were baked for a period of time and pulverized in an agate mortar to produce particles mainly composed of lithium-containing nickel oxide represented by a composition formula of Li _1.15 Ni _0.85 O _1.85 F _0.15 . The average particle size of the obtained particles was 8.5 μm. 5 mol of a mixed aqueous solution having the same composition as in Example 10 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in 1 atmosphere of pure water oxygen. A film (thickness: 20 nm) containing LiCoO ₂ as a main component was formed on the entire surface of the particles by epitaxial growth. LiCoO ₂ of the film has a c-axis orientation of the L
It had the same crystal structure as the direction of the c-axis of i _1.15 Ni _0.85 O _1.85 F _0.15 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 14 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 0.8: 0.85: 0.35, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, the mixture was baked at 650 ° C. for 20 hours, and crushed in an agate mortar, whereby the composition formula was L.
Particles mainly composed of lithium-containing nickel oxide represented by i _1.15 Ni _0.85 O _1.7 F _0.3 were produced. The average particle size of the obtained particles was 8.5 μm. 5 mol of a mixed aqueous solution having the same composition as in Example 10 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in one atmosphere of pure water oxygen. L is epitaxially grown on the entire surface of the particles.
A film (thickness: 20 nm) containing iCoO ₂ as a main component was formed. LiCoO ₂ of the film has a c-axis orientation of the L
It had the same crystal structure as the direction of the c-axis of i _1.15 Ni _0.85 O _1.7 F _0.3 .

A positive electrode was produced in the same manner as in Example 1 except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 15 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 1.14: 0.8: 0.06, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, the mixture was baked at 650 ° C. for 20 hours, and crushed in an agate mortar, whereby the composition formula was L.
Particles mainly composed of lithium-containing nickel oxide represented by i _1.2 Ni _0.8 O _1.95 F _0.05 were produced. The average particle size of the obtained particles was 8.5 μm. 5 mol of a mixed aqueous solution having the same composition as in Example 10 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in 1 atm of pure water oxygen. A film (thickness: 20 nm) containing LiCoO ₂ as a main component was formed on the entire surface of the particles by epitaxial growth. LiCoO ₂ of the film has a c-axis orientation of the L
It had the same crystal structure as the direction of the c-axis of i _1.2 Ni _0.8 O _1.95 F _0.05 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 16 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 0.95: 0.8: 0.25, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, the mixture was baked at 650 ° C. for 20 hours, and crushed in an agate mortar, whereby the composition formula was L.
Particles mainly composed of lithium-containing nickel oxide represented by i _1.2 Ni _0.8 O _1.8 F _0.2 were produced. The average particle size of the obtained particles was 8.5 μm. 5 mol of a mixed aqueous solution having the same composition as in Example 10 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in 1 atm of pure water oxygen. A film (thickness: 20 nm) containing LiCoO ₂ as a main component was formed on the entire surface of the particles by epitaxial growth. LiCoO ₂ of the film has a c-axis orientation of the L
It had the same crystal structure as the direction of the c-axis of i _1.2 Ni _0.8 O _1.8 F _0.2 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 17 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed in a molar ratio of 0.8: 0.8: 0.4, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, baked at 650 ° C. for 20 hours and pulverized in an agate mortar, whereby the composition formula is Li
Particles mainly composed of lithium-containing nickel oxide represented by _1.2 Ni _0.8 O _1.65 F _0.35 were produced. The average particle size of the obtained particles was 8.5 μm. 5 cc of a mixed aqueous solution having the same composition as in Example 10 was added to 1 mol of the particles,
After the solution is sufficiently impregnated into the particles, the particles are calcined at 550 ° C. for 20 hours in one atmosphere of pure water and oxygen, whereby LiC is epitaxially grown on the entire surface of the particles.
A film containing oO ₂ as a main component (having a thickness of 20 nm) was formed. LiCoO ₂ of the film has a c-axis direction of Li
It had the same crystal structure as the direction of the c-axis of _1.2 Ni _0.8 O _1.65 F _0.35 .

A positive electrode was produced in the same manner as in Example 1 except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 9 The molar ratio of LiOH.H ₂ O to Ni (OH) ₂ was 1.15:
0.85 and mixed at 550 ° C. in 1 atmosphere of pure water oxygen.
After holding for a period of time, the mixture was calcined at 650 ° C. for 20 hours and pulverized in an agate mortar to give a composition formula of Li _1.15 Ni _0.85 O ₂
Particles containing a lithium-containing nickel oxide represented by the following formula as a main component were produced. The average particle size of the obtained particles is 8.5 μm.
Met. 5 mol of a mixed aqueous solution having the same composition as in Example 10 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles.
By firing for 0 hours, a film (thickness: 20 nm) containing LiCoO ₂ as a main component was formed on the entire surface of the particles by epitaxial growth. LiCoO _{2 of the} film
_Had a crystal structure in which the direction of the c-axis was the same as the direction of the Li _1.15 Ni _0.85 O ₂ c-axis.

A positive electrode was produced in the same manner as in Example 1 except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 10 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.85: 1.0: 0.15, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, the mixture was baked at 650 ° C. for 20 hours, and crushed in an agate mortar, whereby the composition formula was L.
The lithium-containing nickel oxide represented by iNiO _1.85 F _{0. 15} to prepare particles consisting mainly. The average particle size of the obtained particles was 8.5 μm. 5 mol of a mixed aqueous solution having the same composition as in Example 10 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. LiCoO ₂ is epitaxially grown on the entire surface of the particles.
Was formed (having a thickness of 20 nm). LiCoO ₂ of the membrane, the orientation of the c-axis is the LiNiO _{1. 85}
The crystal had the same crystal structure as that of the c-axis of F _0.15 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 11 The molar ratio of LiOH.H ₂ O to Ni (OH) ₂ was 1.02.
5: 0.975 and mixed in pure water at 1 atm.
After 5 hours at ° C., and calcined at 650 ° C. 20 hours, the composition formula by grinding in an agate mortar Li _1.025 Ni
Particles mainly composed of lithium-containing nickel oxide represented by _0.975 O ₂ were produced. The average particle size of the obtained particles was 8.5 μm. 5 mol of a mixed aqueous solution having the same composition as in Example 10 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles.
By baking at 50 ° C. for 20 hours, a film (thickness: 20 nm) containing LiCoO ₂ as a main component was formed on the entire surface of the particles by epitaxial growth. Li of the film
CoO ₂ has a c-axis orientation of the above Li _1.025 Ni _0.975 O
It had the same crystal structure as the direction of the c-axis of ₂ .

A positive electrode was produced in the same manner as in Example 1 except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 12 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.85: 0.95: 0.2, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, the mixture was baked at 650 ° C. for 20 hours, and crushed in an agate mortar, whereby the composition formula was L.
Particles mainly composed of lithium-containing nickel oxide represented by i _1.05 Ni _0.95 O _1.83 F _0.17 were produced. The average particle size of the obtained particles was 8.5 μm. 5 cc of a mixed aqueous solution having the same composition as in Example 10 was added to 1 mol of the particles,
After the solution is sufficiently impregnated into the particles, the particles are calcined at 550 ° C. for 20 hours in one atmosphere of pure water and oxygen, whereby LiC is epitaxially grown on the entire surface of the particles.
A film containing oO ₂ as a main component (having a thickness of 20 nm) was formed. LiCoO ₂ of the film has a c-axis orientation of the Li _1.
05 Ni _0.95 O _1.83 F _{0.17 had} the same crystal structure as the c-axis direction.

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 13 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.85: 0.9: 0.25, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, the mixture was baked at 650 ° C. for 20 hours, and crushed in an agate mortar, whereby the composition formula was L.
Particles mainly composed of lithium-containing nickel oxide represented by i _1.1 Ni _0.9 O _1.79 F _0.21 were produced. The average particle size of the obtained particles was 8.5 μm. 5 cc of a mixed aqueous solution having the same composition as in Example 10 was added to 1 mol of the particles,
After the solution is sufficiently impregnated into the particles, the particles are calcined at 550 ° C. for 20 hours in one atmosphere of pure water and oxygen, whereby LiC is epitaxially grown on the entire surface of the particles.
A film containing oO ₂ as a main component (having a thickness of 20 nm) was formed. LiCoO ₂ of the film has a c-axis orientation of the Li _1.
It had a crystal structure is the same as ₁ Ni _0.9 O _1.79 F _0.21 c-axis orientation of the.

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 14 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.75: 0.9: 0.35, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, the mixture was baked at 650 ° C. for 20 hours, and crushed in an agate mortar, whereby the composition formula was L.
Particles mainly composed of lithium-containing nickel oxide represented by i _1.1 Ni _0.9 O _1.7 F _0.3 were prepared. The average particle size of the obtained particles was 8.5 μm. 5 cc of a mixed aqueous solution having the same composition as in Example 10 was added to 1 mol of the particles,
After the solution is sufficiently impregnated into the particles, the particles are calcined at 550 ° C. for 20 hours in one atmosphere of pure water and oxygen, whereby LiC is epitaxially grown on the entire surface of the particles.
A film containing oO ₂ as a main component (having a thickness of 20 nm) was formed. LiCoO ₂ of the film has a c-axis orientation of the Li _1.
1 Ni _0.9 O _1.7 F _{0.3 had} the same crystal structure as the direction of the c-axis.

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 15 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 0.75: 0.85: 0.4, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, the mixture was baked at 650 ° C. for 20 hours, and crushed in an agate mortar, whereby the composition formula was L.
i _1.15 Ni _0.85 O _1.62 F _0.38 Particles containing lithium-containing nickel oxide as a main component were prepared. The average particle size of the obtained particles was 8.5 μm. 5 cc of a mixed aqueous solution having the same composition as in Example 10 was added to 1 mol of the particles,
After the solution is sufficiently impregnated into the particles, the particles are calcined at 550 ° C. for 20 hours in one atmosphere of pure water and oxygen, whereby LiC is epitaxially grown on the entire surface of the particles.
A film containing oO ₂ as a main component (having a thickness of 20 nm) was formed. LiCoO ₂ of the film has a c-axis orientation of the Li _1.
It had a crystal structure is the same as the ₁₅ Ni _0.85 O _1.62 F _0.38 c-axis orientation of the.

A positive electrode was produced in the same manner as in Example 1 except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

After charging the batteries of Examples 10 to 17 and Comparative Examples 9 to 15 at 4.2 mA at a current value of 1 mA, the current was stopped for 30 minutes, and then discharging was performed at a current value of 1 mA. The cycle is repeated until the voltage reaches 0 V, and the current is stopped again for 30 minutes. Changes in the discharge capacity according to the number of cycles are measured. The initial charge capacity and the discharge capacity at the 100th cycle are shown in Table 4 below.

[0149]

[Table 4]

As apparent from Table 4, Examples 10 to 1
It can be seen that the battery of No. 7 has a better charge / discharge cycle life than the batteries of Comparative Examples 9 to 15. This is because, as shown in Table 3 and FIG.
Particles satisfying the two characteristics, ie, the above (4) to (7)
This is because particles containing a lithium-containing nickel oxide having a composition that satisfies the formula at the same time as a main component, and a film having LiCoO ₂ as a main component formed on the entire surface are included as an active material.

Y / 2 ≦ x <(y + 1) / 3 (4) y> 0 (5) x ≧ 0.05 (6) 1.9 ≦ u ≦ 2.1 (7) On the other hand, the cycle life of the batteries of Comparative Examples 9 to 15 is short because the lithium-containing nickel oxide having a composition in which the positive electrodes of these batteries are out of the range defined by the above formulas (4) to (7) It is because particles mainly composed of

Example 18 A composition formula of Li _1.05 Ni was obtained in the same manner as in Example 10.
Particles having a mean particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by _0.95 O _1.96 F _0.04 as a main component were produced. On the other hand, a 1 mol / l mixed aqueous solution comprising lithium nitrate and aluminum nitrate was prepared. The molar ratio of lithium and aluminum contained in the mixed aqueous solution was 1: 1. 5 cc of the mixed aqueous solution per 1 mol of the particles
Is added, and this solution is sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in 1 atm of pure water and oxygen to form a film containing LiAlO ₂ as a main component by epitaxial growth on the entire surface of the particles. (The thickness is 20n
m) was formed. LiAlO ₂ of the film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.05 Ni _0.95 O _1.96 F _0.04 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 19 By a method similar to that in Example 11, the composition formula was Li _1.1 Ni
Particles having a mean particle size of 8.5 μm mainly composed of a lithium-containing nickel oxide represented by _0.9 O _1.9 F _0.1 were prepared. 5 mol of a mixed aqueous solution having the same composition as in Example 18 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of LiAlO ₂ was formed on the entire surface of the particles by epitaxial growth. LiAlO ₂ of the film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.1 Ni _0.9 O _1.9 F _0.1 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 20 A composition formula of Li _1.1 Ni was obtained in the same manner as in Example 12.
Particles having a mean particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by _0.9 O _1.83 F _0.17 as a main component were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 18 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in 1 atm of pure water oxygen. A film (thickness: 20 nm) mainly composed of LiAlO ₂ was formed on the entire surface of the particles by epitaxial growth. LiAlO ₂ of the film is c
Axis orientation had a same a crystal structure and orientation of the c-axis of the _{Li 1.1 Ni 0.9 O 1.83 F 0.17} .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 21 A composition formula of Li _1.15 Ni was obtained in the same manner as in Example 13.
Particles having a mean particle size of 8.5 μm mainly composed of a lithium-containing nickel oxide represented by _0.85 O _1.85 F _0.15 were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 18 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of LiAlO ₂ was formed on the entire surface of the particles by epitaxial growth. LiAlO ₂ of the film is c
It had a crystal structure in which the direction of the axis was the same as the direction of the c-axis of Li _1.15 Ni _0.85 O _1.85 F _0.15 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 22 A composition formula of Li _1.15 Ni was obtained in the same manner as in Example 14.
Particles containing lithium-containing nickel oxide represented by _0.85 O _1.7 F _0.3 as a main component and having an average particle diameter of 8.5 μm were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 18 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of LiAlO ₂ was formed on the entire surface of the particles by epitaxial growth. LiAlO ₂ of the film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.15 Ni _0.85 O _1.7 F _0.3 .

A positive electrode was prepared in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 23 By a method similar to that in Example 15, the composition formula was Li _1.2 Ni
Particles containing lithium-containing nickel oxide represented by _0.8 O _1.95 F _0.05 as a main component and having an average particle diameter of 8.5 μm were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 18 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of LiAlO ₂ was formed on the entire surface of the particles by epitaxial growth. LiAlO ₂ of the film is c
It had a crystal structure in which the direction of the axis was the same as the direction of the c-axis of Li _1.2 Ni _0.8 O _1.95 F _0.05 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 24 A composition formula of Li _1.2 Ni was obtained in the same manner as in Example 16.
Particles having a mean particle size of 8.5 μm mainly composed of a lithium-containing nickel oxide represented by _0.8 O _1.8 F _0.2 were prepared. 5 mol of a mixed aqueous solution having the same composition as in Example 18 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of LiAlO ₂ was formed on the entire surface of the particles by epitaxial growth. LiAlO ₂ of the film is c
It had a crystal structure in which the direction of the axis was the same as the direction of the c-axis of Li _1.2 Ni _0.8 O _1.8 F _0.2 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 25 A composition formula of Li _1.2 Ni was obtained in the same manner as in Example 17.
Particles having a mean particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by _0.8 O _1.65 F _0.35 as a main component were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 18 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in 1 atmosphere of pure water oxygen. A film (thickness: 20 nm) mainly composed of LiAlO ₂ was formed on the entire surface of the particles by epitaxial growth. LiAlO ₂ of the film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.2 Ni _0.8 O _1.65 F _0.35 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 16 The composition formula was Li _1.15 Ni _{0.85 in the same} manner as in Comparative Example 9.
Particles mainly composed of lithium-containing nickel oxide represented by O ₂ and having an average particle diameter of 8.5 μm were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 18 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles.
By firing at 550 ° C. for 20 hours in one atmosphere of pure water oxygen, a film (thickness: 20 nm) containing LiAlO ₂ as a main component was formed on the entire surface of the particles by epitaxial growth. LiAlO ₂ of the film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of _1.15 Ni _0.85 O _{2 of} Li.

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 17 The composition formula was LiNiO _{1.85 in the same} manner as in Comparative Example 10.
Particles containing lithium-containing nickel oxide represented by F _0.15 as a main component and having an average particle size of 8.5 μm were produced. 5 cc of a mixed aqueous solution having the same composition as in Example 18 was added to 1 mol of the particles.
Is added, and this solution is sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in 1 atm of pure water and oxygen to form a film containing LiAlO ₂ as a main component by epitaxial growth on the entire surface of the particles. (The thickness is 20n
m) was formed. LiAlO ₂ of the film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of LiNiO _1.85 F _0.15 .

A positive electrode was produced in the same manner as in Example 1 except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 18 A composition formula of Li _1.025 Ni was obtained in the same manner as in Comparative Example 11.
Particles having a mean particle size of 8.5 μm mainly composed of a lithium-containing nickel oxide represented by _0.975 O ₂ were prepared. A mixed aqueous solution 5c having the same composition as in Example 18 was added to 1 mol of the particles.
After adding c, the solution is sufficiently impregnated into the particles, and baked at 550 ° C. for 20 hours in 1 atm of pure water and oxygen, whereby LiAlO ₂ is a main component by epitaxial growth on the entire surface of the particles. Film (20n thickness)
m) was formed. LiAlO ₂ of the film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.025 Ni _0.975 O ₂ .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 19 The composition formula was Li _1.05 Ni in the same manner as in Comparative Example 12.
Particles having a mean particle size of 8.5 μm containing a lithium-containing nickel oxide represented by _0.95 O _1.83 F _0.17 as a main component were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 18 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in 1 atmosphere of pure water oxygen. A film (thickness: 20 nm) mainly composed of LiAlO ₂ was formed on the entire surface of the particles by epitaxial growth. LiAlO ₂ of the film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.05 Ni _0.95 O _1.83 F _0.17 .

A positive electrode was produced in the same manner as in Example 1 except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 20 The composition formula was Li _1.1 Ni in the same manner as in Comparative Example 13.
Particles containing lithium-containing nickel oxide represented by _0.9 O _1.79 F _0.21 as a main component and having an average particle diameter of 8.5 μm were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 18 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in 1 atmosphere of pure water oxygen. A film (thickness: 20 nm) mainly composed of LiAlO ₂ was formed on the entire surface of the particles by epitaxial growth. LiAlO ₂ of the film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.1 Ni _0.9 O _1.79 F _0.21 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 21 A composition formula of Li _1.1 Ni was obtained in the same manner as in Comparative Example 14.
Particles having a mean particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by _0.9 O _1.7 F _0.3 as a main component were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 18 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of LiAlO ₂ was formed on the entire surface of the particles by epitaxial growth. LiAlO ₂ of the film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.1 Ni _0.9 O _1.7 F _0.3 .

A positive electrode was prepared in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 22 The composition formula was Li _1.15 Ni in the same manner as in Comparative Example 15.
Particles having a mean particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by _0.85 O _1.62 F _0.38 as a main component were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 18 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of LiAlO ₂ was formed on the entire surface of the particles by epitaxial growth. LiAlO ₂ of the film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.15 Ni _0.85 O _1.62 F _0.38 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

After charging the batteries of Examples 18 to 25 and Comparative Examples 16 to 22 at 4.2 mA at a current value of 1 mA, the current was stopped for 30 minutes, and then discharging was performed at a current value of 1 mA.
The cycle is repeated until the voltage reaches 3.0 V, and the current is again stopped for 30 minutes. The change in the discharge capacity according to the number of cycles is measured. The initial charge capacity and the discharge capacity at the 100th cycle are shown in Table 5 below.

[0183]

[Table 5]

As is clear from Table 5, Examples 18 to 2
It can be seen that the battery of No. 5 has better charge / discharge cycle life than the batteries of Comparative Examples 16 to 22. This is because, as shown in Table 3 and FIG. 7, the positive electrodes of the batteries of Examples 18 to 25 satisfy the two characteristics, that is, the above-described (4) to (4).
This is because particles containing lithium-containing nickel oxide having a composition that satisfies the expression (7) at the same time as a main component and having a film mainly composed of LiAlO ₂ formed on the entire surface are included as an active material.

On the other hand, the cycle life of the batteries of Comparative Examples 16 to 22 was short because the lithium-containing nickel having a composition in which the positive electrode of these batteries was out of the range defined by the above formulas (4) to (7). This is because it contains particles mainly composed of an oxide.

Example 26 By a method similar to that in Example 10, the composition formula was Li _1.05 Ni
Particles having a mean particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by _0.95 O _1.96 F _0.04 as a main component were produced. On the other hand, a 1 mol / l mixed aqueous solution composed of lithium nitrate and manganese nitrate was prepared. The molar ratio of lithium and manganese contained in the mixed aqueous solution was 2: 1. 5 mol of the mixed aqueous solution is added to 1 mol of the particles, and the solution is sufficiently impregnated into the particles, and then baked at 550 ° C. for 20 hours in 1 atm of pure water and oxygen to epitaxially grow on the entire surface of the particles. By L
A film (thickness: 20 nm) containing i ₂ MnO ₃ as a main component was formed. Li ₂ MnO _{3 of the} film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.05 Ni _0.95 O _1.96 F _0.04 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 27 By a method similar to that in Example 11, the composition formula was Li _1.1 Ni
Particles having a mean particle size of 8.5 μm mainly composed of a lithium-containing nickel oxide represented by _0.9 O _1.9 F _0.1 were prepared. 5 mol of a mixed aqueous solution having the same composition as in Example 26 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles, and then fired at 550 ° C. for 20 hours in 1 atm of pure water oxygen. A film (thickness: 20 nm) mainly composed of Li ₂ MnO ₃ was formed on the entire surface of the particles by epitaxial growth. Li ₂ MnO _{3 of the} film is:
orientation of the c-axis was achieved with the same a crystal structure and orientation of the c-axis of the _{Li 1.1 Ni 0.9 O 1.9 F 0.1} .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 28 By a method similar to that in Example 12, the composition formula was Li _1.1 Ni
Particles having a mean particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by _0.9 O _1.83 F _0.17 as a main component were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 26 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of Li ₂ MnO ₃ was formed on the entire surface of the particles by epitaxial growth. Li ₂ MnO of the film
₃ indicates that the direction of the c-axis is Li _1.1 Ni _0.9 O _1.83 F _0.17
Has the same crystal structure as the direction of the c-axis.

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 29 By a method similar to that in Example 13, the composition formula was Li _1.15 Ni
Particles having a mean particle size of 8.5 μm mainly composed of a lithium-containing nickel oxide represented by _0.85 O _1.85 F _0.15 were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 26 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of Li ₂ MnO ₃ was formed on the entire surface of the particles by epitaxial growth. Li ₂ MnO of the film
₃ has a c-axis orientation of Li _1.15 Ni _0.85 O _1.85 F _0.15
Has the same crystal structure as the direction of the c-axis.

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 30 By a method similar to that in Example 14, the composition formula was Li _1.15 Ni
Particles containing lithium-containing nickel oxide represented by _0.85 O _1.7 F _0.3 as a main component and having an average particle diameter of 8.5 μm were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 26 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles, and then fired at 550 ° C. for 20 hours in 1 atm of pure water oxygen. A film (thickness: 20 nm) mainly composed of Li ₂ MnO ₃ was formed on the entire surface of the particles by epitaxial growth. Li ₂ MnO _{3 of the} film is:
It had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.15 Ni _0.85 O _1.7 F _0.3 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 31 By a method similar to that in Example 15, the composition formula was Li _1.2 Ni
Particles containing lithium-containing nickel oxide represented by _0.8 O _1.95 F _0.05 as a main component and having an average particle diameter of 8.5 μm were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 26 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of Li ₂ MnO ₃ was formed on the entire surface of the particles by epitaxial growth. Li ₂ MnO of the film
₃ indicates that the direction of the c-axis is Li _1.2 Ni _0.8 O _1.95 F _0.05
Has the same crystal structure as the direction of the c-axis.

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 32 By a method similar to that in Example 16, the composition formula was Li _1.2 Ni
Particles having a mean particle size of 8.5 μm mainly composed of a lithium-containing nickel oxide represented by _0.8 O _1.8 F _0.2 were prepared. 5 mol of a mixed aqueous solution having the same composition as in Example 26 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of Li ₂ MnO ₃ was formed on the entire surface of the particles by epitaxial growth. Li ₂ MnO of the film
₃ indicates that the direction of the c-axis is Li _1.2 Ni _0.8 O _1.8 F _0.2
Has the same crystal structure as the direction of the c-axis.

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 33 By a method similar to that in Example 17, the composition formula was Li _1.2 Ni
Particles having a mean particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by _0.8 O _1.65 F _0.35 as a main component were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 26 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of Li ₂ MnO ₃ was formed on the entire surface of the particles by epitaxial growth. Li ₂ MnO _{3 of the} film is:
It had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.2 Ni _0.8 O _1.65 F _0.35 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 23 By a method similar to that of Comparative Example 9, the composition formula was Li _1.15 Ni _0.85
Particles mainly composed of lithium-containing nickel oxide represented by O ₂ and having an average particle diameter of 8.5 μm were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 26 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles.
A film mainly composed of Li ₂ MnO ₃ (thickness: 20 nm) is formed by baking at 550 ° C. for 20 hours in one atmosphere of pure water oxygen by epitaxial growth on the entire surface of the particles.
Was formed. Li ₂ MnO _{3 of the} film had a crystal structure in which the direction of the c-axis was the same as the direction of the _1.15 Ni _0.85 O ₂ c-axis of Li.

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 24 A composition formula of LiNiO _1.85 was obtained in the same manner as in Comparative Example 10.
Particles containing lithium-containing nickel oxide represented by F _0.15 as a main component and having an average particle size of 8.5 μm were produced. 5 cc of a mixed aqueous solution having the same composition as in Example 26 was added to 1 mol of the particles.
Is added, and the solution is sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in 1 atm of pure water and oxygen, whereby Li ₂ MnO ₃ as a main component is epitaxially grown on the entire surface of the particles. Film (thickness is 20n)
m) was formed. Li ₂ MnO _{3 of the} film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of LiNiO _1.85 F _0.15 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 25 A composition formula of Li _1.025 Ni was obtained in the same manner as in Comparative Example 11.
Particles having a mean particle size of 8.5 μm mainly composed of a lithium-containing nickel oxide represented by _0.975 O ₂ were prepared. A mixed aqueous solution 5c having the same composition as in Example 26 was added to 1 mol of the particles.
c, and the solution is sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in 1 atm of pure water and oxygen, whereby Li ₂ MnO ₃ is a main component by epitaxial growth on the entire surface of the particles. Film (thickness is 20n)
m) was formed. Li ₂ MnO _{3 of the} film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.025 Ni _0.975 O ₂ .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 26 The composition formula was Li _1.05 Ni in the same manner as in Comparative Example 12.
Particles having a mean particle size of 8.5 μm containing a lithium-containing nickel oxide represented by _0.95 O _1.83 F _0.17 as a main component were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 26 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles, and then fired at 550 ° C. for 20 hours in 1 atm of pure water oxygen. A film (thickness: 20 nm) mainly composed of Li ₂ MnO ₃ was formed on the entire surface of the particles by epitaxial growth. Li ₂ MnO _{3 of the} film is:
It had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.05 Ni _0.95 O _1.83 F _0.17 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 27 A composition formula of Li _1.1 Ni was obtained in the same manner as in Comparative Example 13.
Particles containing lithium-containing nickel oxide represented by _0.9 O _1.79 F _0.21 as a main component and having an average particle diameter of 8.5 μm were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 26 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of Li ₂ MnO ₃ was formed on the entire surface of the particles by epitaxial growth. Li ₂ MnO _{3 of the} film is:
orientation of the c-axis was achieved with the same a crystal structure and orientation of the c-axis of the _{Li 1.1 Ni 0.9 O 1.79 F 0.21} .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 28 A composition formula of Li _1.1 Ni was obtained in the same manner as in Comparative Example 14.
Particles having a mean particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by _0.9 O _1.7 F _0.3 as a main component were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 26 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of Li ₂ MnO ₃ was formed on the entire surface of the particles by epitaxial growth. Li ₂ MnO _{3 of the} film is:
orientation of the c-axis was achieved with the same a crystal structure and orientation of the c-axis of the _{Li 1.1 Ni 0.9 O 1.7 F 0.3} .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 29 A composition formula of Li _1.15 Ni was obtained in the same manner as in Comparative Example 15.
Particles having a mean particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by _0.85 O _1.62 F _0.38 as a main component were produced. 5 mol of a mixed aqueous solution having the same composition as in Example 26 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles. A film (thickness: 20 nm) mainly composed of Li ₂ MnO ₃ was formed on the entire surface of the particles by epitaxial growth. Li ₂ MnO _{3 of the} film is:
It had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.15 Ni _0.85 O _1.62 F _0.38 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

After charging the batteries of Examples 26 to 33 and Comparative Examples 23 to 29 at 4.2 mA at a current value of 1 mA, the current was stopped for 30 minutes, and then discharging was performed at a current value of 1 mA.
The cycle is repeated until the voltage reaches 3.0 V, and the current is again stopped for 30 minutes. The change in the discharge capacity according to the number of cycles is measured, and the initial charge capacity and the discharge capacity at the 100th cycle are shown in Table 6 below.

[0219]

[Table 6]

As is clear from Table 6, Examples 26 to 3
It can be seen that the battery of No. 3 has better charge / discharge cycle life than the batteries of Comparative Examples 23 to 29. This is because, as shown in Table 3 and FIG. 7, the positive electrodes of the batteries of Examples 26 to 33 satisfy the two characteristics, that is, the particles (4) to (4) described above.
This is because particles containing a lithium-containing nickel oxide having a composition that satisfies the expression (7) at the same time as a main component, and a film having a film mainly composed of Li ₂ MnO ₃ formed on the entire surface are included as an active material.

On the other hand, the cycle life of the batteries of Comparative Examples 23 to 29 was short because the lithium-containing nickel having a composition in which the positive electrode of these batteries was out of the range defined by the above formulas (4) to (7). This is because it contains particles mainly composed of an oxide.

Example 34 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.98: 0.92: 0.1, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, the mixture was baked at 650 ° C. for 20 hours, and crushed in an agate mortar, whereby the composition formula was L.
The i _1.075 Ni _{0.92 5} O _1.9 lithium-containing nickel oxide represented by F _0.1 to prepare particles consisting mainly. The average particle size of the obtained particles was 8.5 μm. On the other hand, a 1 mol / l film forming aqueous solution comprising lithium nitrate and cobalt nitrate was prepared. The molar ratio of lithium and cobalt contained in this aqueous solution was 1: 1. The particles 1
5 cc of the aqueous solution was added to the mole, and the solution was sufficiently impregnated into the particles.
By firing at 20 ° C. for 20 hours, a film (thickness: 10 nm) containing LiCoO ₂ as a main component was formed on the entire surface of the particles by epitaxial growth. LiCo of the film
O _2, the orientation of the c-axis Li _1.075 Ni _{0.92 5} O _1.9
It had a crystal structure is the same as the direction of the c axis of F _0.1.

A positive electrode was prepared in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 35 By a method similar to that in Example 34, the composition formula was Li _1.075 Ni.
Particles having a mean particle size of 8.5 μm mainly composed of a lithium-containing nickel oxide represented by _0.925 O _1.9 F _0.1 were prepared. On the other hand, a 0.4 mol / l mixed aqueous solution composed of lithium nitrate and cobalt nitrate was prepared. The molar ratio of lithium and cobalt contained in the mixed aqueous solution was 1: 1. 5 cc of the mixed aqueous solution per 1 mol of the particles
Is added, and the solution is sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in 1 atm of pure water and oxygen to form a film containing LiCoO ₂ as a main component by epitaxial growth on the entire surface of the particles. (4 nm thick)
Was formed. LiCoO ₂ of the film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.075 Ni _0.925 O _1.9 F _0.1 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 36 By a method similar to that in Example 34, the composition formula was Li _1.075 Ni.
Particles having a mean particle size of 8.5 μm mainly composed of a lithium-containing nickel oxide represented by _0.925 O _1.9 F _0.1 were prepared. On the other hand, a 2 mol / l mixed aqueous solution comprising lithium nitrate and cobalt nitrate was prepared. The molar ratio of lithium and cobalt contained in the mixed aqueous solution was 1: 1.
I made it. 5 mol of the mixed aqueous solution is added to 1 mol of the particles, and the solution is sufficiently impregnated into the particles, and then baked at 550 ° C. for 20 hours in 1 atm of pure water and oxygen to epitaxially grow on the entire surface of the particles. By L
A film (thickness: 20 nm) containing iCoO ₂ as a main component was formed. LiCoO ₂ of the film has a c-axis direction of Li
_The crystal had the same crystal structure as the direction of the c-axis of _1.075 Ni _0.925 O _1.9 F _0.1 .

A positive electrode was prepared in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 37 By a method similar to that in Example 34, the composition formula was Li _1.075 Ni.
Particles having a mean particle size of 8.5 μm mainly composed of a lithium-containing nickel oxide represented by _0.925 O _1.9 F _0.1 were prepared. A positive electrode was produced in the same manner as in Example 1 except that the obtained particles were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, FIG.
The positive electrode evaluation battery shown in FIG.

Comparative Example 30 LiOH.H ₂ O and Ni (OH) ₂ were mixed at a molar ratio of 1.0.
3: Mixing at 0.97, 550 ° C. in 1 atm of pure water oxygen
And then calcined at 650 ° C. for 20 hours, and pulverized in an agate mortar to give a composition formula of Li _1.02 Ni _0.98
Particles containing lithium-containing nickel oxide represented by O _2.02 as a main component were produced. The average particle size of the obtained particles is 8.
It was 5 μm. 5 cc of a film-forming aqueous solution having the same composition as in Example 34 was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles.
By firing at 0 ° C. for 20 hours, a film (thickness: 10 nm) mainly composed of LiCoO ₂ was formed on the entire surface of the particles by epitaxial growth. LiC of the film
oO ₂ had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.02 Ni _0.98 O _2.02 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 31 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 0.78: 0.92: 0.3, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, the mixture was baked at 650 ° C. for 20 hours, and crushed in an agate mortar, whereby the composition formula was L.
The i _1.075 Ni _{0.92 5} O _1.7 lithium-containing nickel oxide represented by F _0.29 to prepare particles consisting mainly. The average particle size of the obtained particles was 8.5 μm. Example 34
5 cc of a film forming aqueous solution having the same composition as described above was added to 1 mol of the particles, and this solution was sufficiently impregnated into the particles.
By firing at 550 ° C. for 20 hours in 1 atm of pure water oxygen, a film (thickness: 10 nm) containing LiCoO ₂ as a main component was formed on the entire surface of the particles by epitaxial growth. LiCoO ₂ of the film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.075 Ni _0.925 O _1.7 F _0.29 .

A positive electrode was produced in the same manner as in Example 1 except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

After charging the batteries of Examples 34 to 37 and Comparative Examples 30 to 31 at 4.2 mA at a current value of 1 mA, the current was stopped for 30 minutes, and then the discharge was performed at a current value of 1 mA.
The cycle is repeated until the current reaches 3.0 V, and the current is again stopped for 30 minutes. The change in the discharge capacity according to the number of cycles is measured. The initial charge capacity and the discharge capacity at the 30th cycle are shown in Table 7 below.

[0232]

[Table 7]

As is clear from Table 7, Examples 34 to 3
It can be seen that the battery of No. 7 has a better charge / discharge cycle life than the batteries of Comparative Examples 30 and 31. Among them, a film mainly containing lithium-containing nickel oxide having a composition that simultaneously satisfies the above formulas (4) to (7) and a film mainly containing LiCoO ₂ is formed on the entire surface. It can be seen that the batteries of Examples 34 to 36 provided with the positive electrode containing the particles as the active material have excellent cycle characteristics.

On the other hand, the cycle life of the batteries of Comparative Examples 30 and 31 was short because the particles used as the positive electrode active material of these batteries had the LiCoO ₂ film formed on the entire surface, but the (4) ) To (7) because the main component is a lithium-containing nickel oxide having a composition outside the range defined by the formulas.

Example 38 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.96: 0.9: 0.15, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, the mixture was baked at 650 ° C. for 20 hours, and crushed in an agate mortar, whereby the composition formula was L.
Particles mainly composed of lithium-containing nickel oxide represented by i _1.1 Ni _0.9 O _1.85 F _0.14 were produced. The average particle size of the obtained particles was 8.5 μm. 5 cc of a film-forming aqueous solution having the same composition as in Example 34 was added to 1 mol of the particles, and the solution was sufficiently impregnated into the particles, and then fired at 550 ° C. for 20 hours in 1 atm of pure water and oxygen. L on the entire surface of the particle by epitaxial growth
A film (thickness: 10 nm) containing iCoO ₂ as a main component was formed. LiCoO ₂ of the film has a c-axis direction of Li
It had the same crystal structure as the direction of the c-axis of _1.1 Ni _0.9 O _1.85 F _0.14 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 39 By a method similar to that in Example 38, the composition formula was Li _1.1 Ni
Particles containing lithium-containing nickel oxide represented by _0.9 O _1.85 F _0.14 as a main component and having an average particle diameter of 8.5 μm were produced. A positive electrode was produced in the same manner as in Example 1 except that the obtained particles were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

The batteries of Examples 38 to 39 were charged at a current value of 1.
After the current reached 4.2 V at mA, the current was stopped for 30 minutes, then the discharge was performed at a current value of 1 mA until the voltage reached 3.0 V, and the cycle of stopping the current again for 30 minutes was repeated. Measure the change in discharge capacity,
Table 8 below shows the initial charge capacity and the discharge capacity at the 30th cycle. Table 8 also shows the initial charge capacity and the discharge capacity at the 30th cycle of the batteries of Comparative Examples 30 and 31.

[0239]

[Table 8]

As apparent from Table 8, Examples 38 and 3
It can be seen that the battery of No. 9 has better cycle life than the batteries of Comparative Examples 30 and 31.

Example 40 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 0.96: 0.92: 0.12, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, 20 minutes at 650 ° C
By calcining for an hour and pulverizing in an agate mortar, particles having a composition formula of Li _1.08 Ni _0.92 O _1.9 F _0.1 and containing lithium-containing nickel oxide as a main component and having an average particle size of 8.5 μm were produced. A positive electrode was produced in the same manner as in Example 1 except that the obtained particles were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 41 By a method similar to that in Example 40, the composition formula was Li _1.08 Ni.
Particles having a mean particle size of 8.5 μm containing a lithium-containing nickel oxide represented by _0.92 O _1.9 F _0.1 as a main component were produced. On the other hand, a 1 mol / l film forming aqueous solution comprising lithium nitrate and cobalt nitrate was prepared. The molar ratio of lithium and cobalt contained in this aqueous solution was 1: 1. 5 mol of the aqueous solution is added to 1 mol of the particles, and the solution is sufficiently impregnated into the particles, and then baked at 550 ° C. for 20 hours in 1 atm of pure water oxygen to thereby epitaxially grow the entire surface of the particles. LiCo
A film containing O ₂ as a main component (having a thickness of 10 nm) was formed.
LiCoO ₂ of the film has a c-axis orientation of the Li _1.08 N
It had the same crystal structure as the direction of the c-axis of i _0.92 O _1.9 F _0.1 .

A positive electrode was produced in the same manner as in Example 1 except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 42 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 0.96: 0.92: 0.12, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, 20 minutes at 650 ° C
By calcining for a period of time and pulverizing in an agate mortar, particles having an average particle size of 4.5 μm and containing lithium-containing nickel oxide represented by the composition formula of Li _1.08 Ni _0.92 O _1.9 F _0.1 as a main component were produced. A positive electrode was produced in the same manner as in Example 1 except that the obtained particles were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 43 By a method similar to that in Example 42, the composition formula was Li _1.08 Ni
Particles having a mean particle size of 4.5 μm mainly composed of a lithium-containing nickel oxide represented by _0.92 O _1.9 F _0.1 were prepared. On the other hand, a 2 mol / l film forming aqueous solution comprising lithium nitrate and cobalt nitrate was prepared. The molar ratio of lithium and cobalt contained in this aqueous solution was 1: 1. 5 mol of the aqueous solution is added to 1 mol of the particles, and the solution is sufficiently impregnated into the particles, and then baked at 550 ° C. for 20 hours in 1 atm of pure water oxygen to thereby epitaxially grow the entire surface of the particles. LiCoO
A film mainly composed of ₂ (having a thickness of 10 nm) was formed. The LiCoO ₂ of the film has a c-axis orientation of the Li _1.08 Ni
It had a crystal structure that was the same as the direction of the c-axis of _0.92 O _1.9 F _0.1 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 32 LiOH.H ₂ O and Ni (OH) ₂ were mixed at a molar ratio of 1: 1 and kept at 550 ° C. for 5 hours in 1 atm of pure water oxygen, and then at 650 ° C. for 20 hours. By baking and pulverizing in an agate mortar, the average particle diameter of which is mainly composed of a lithium-containing nickel oxide represented by a composition formula of LiNiO ₂ is 8.5 μm.
m particles were produced. A positive electrode was produced in the same manner as in Example 1 except that the obtained particles were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

The batteries of Examples 40 to 43 and Comparative Example 32 were charged until the current reached 4.2 V at a current value of 1 mA.
The current was stopped for 30 minutes, and then discharge was performed at a current value of 1 mA.
The cycle is repeated until the voltage reaches 0 V, and the current is stopped again for 30 minutes. The cycle is repeated 50 times, and the discharge capacity of each cycle is measured. The result is shown in FIG.

As is apparent from FIG.
It can be seen that the battery of No. 3 can maintain a high capacity for 50 cycles. On the other hand, the initial capacity of the battery of Comparative Example 32 was higher than that of the batteries of Examples 40 to 43.
It can be seen that the discharge capacity at the 0th cycle is extremely low and the cycle life is shorter than those of the batteries of Examples 40 to 43.

Example 44 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 0.9: 0.9: 0.2, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, baked at 650 ° C. for 20 hours and pulverized in an agate mortar, whereby the composition formula is Li
Particles containing lithium-containing nickel oxide represented by _1.1 Ni _0.9 O _1.83 F _0.17 as a main component and having an average particle diameter of 8.5 μm were produced. On the other hand, a 1 mol / l film forming aqueous solution comprising lithium nitrate and cobalt nitrate was prepared. In addition,
The molar ratio of lithium and cobalt contained in this aqueous solution was 1: 1. 5 mol of the aqueous solution is added to 1 mol of the particles, the solution is sufficiently impregnated into the particles, and then baked at 550 ° C. for 20 hours in 1 atm of pure water oxygen, thereby epitaxially growing the entire surface of the particles by epitaxial growth. A film (having a thickness of 10 nm) containing LiCoO ₂ as a main component was formed. LiCoO ₂ of the film had a crystal structure in which the direction of the c-axis was the same as the direction of the c-axis of Li _1.1 Ni _0.9 O _1.83 F _0.17 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 45 By a method similar to that in Example 44, the composition formula was Li _1.1 Ni.
Particles having a mean particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by _0.9 O _1.83 F _0.17 as a main component were produced. On the other hand, a 1 mol / l film forming aqueous solution comprising lithium nitrate and cobalt nitrate was prepared. The molar ratio of lithium and cobalt contained in this aqueous solution was 1: 1. 15 cc of the aqueous solution was added to 1 mol of the particles, and the solution was sufficiently impregnated into the particles.
By baking at 550 ° C. for 20 hours in the atmosphere, LiC is epitaxially grown on the entire surface of the particles.
A film (thickness: 30 nm) containing oO ₂ as a main component was formed. LiCoO ₂ of the film has a c-axis direction of Li
It had the same crystal structure as the direction of the c-axis of _1.1 Ni _0.9 O _1.83 F _0.17 .

A positive electrode was produced in the same manner as in Example 1 except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 46 By a method similar to that in Example 44, the composition formula was Li _1.1 Ni.
Particles having a mean particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by _0.9 O _1.83 F _0.17 as a main component were produced. On the other hand, a 2 mol / l film forming aqueous solution comprising lithium nitrate and cobalt nitrate was prepared. The molar ratio of lithium and cobalt contained in this aqueous solution was 1: 1. 12.5 cc of the aqueous solution was added to 1 mol of the particles, and the solution was sufficiently impregnated into the particles, and then calcined at 550 ° C. for 20 hours in 1 atm of pure water and oxygen to cover the entire surface of the particles. A film (thickness: 50 nm) containing LiCoO ₂ as a main component was formed by epitaxial growth. LiCoO ₂ of the film has a c-axis orientation of the L
It had the same crystal structure as the direction of the c-axis of i _1.1 Ni _0.9 O _1.83 F _0.17 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Example 47 By a method similar to that in Example 44, the composition formula was Li _1.1 Ni
Particles having a mean particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by _0.9 O _1.83 F _0.17 as a main component were produced. On the other hand, a 2 mol / l film forming aqueous solution comprising lithium nitrate and cobalt nitrate was prepared. The molar ratio of lithium and cobalt contained in this aqueous solution was 1: 1. 25 mol of the aqueous solution was added to 1 mol of the particles, and the solution was sufficiently impregnated into the particles.
By baking at 550 ° C. for 20 hours in the atmosphere, LiC is epitaxially grown on the entire surface of the particles.
A film (having a thickness of 100 nm) containing oO ₂ as a main component was formed. LiCoO ₂ of the film has a c-axis direction of Li
It had the same crystal structure as the direction of the c-axis of _1.1 Ni _0.9 O _1.83 F _0.17 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using this positive electrode, the same negative electrode, reference electrode and non-aqueous electrolyte as in Example 1, the above-described positive electrode evaluation battery shown in FIG. 5 was assembled.

Comparative Example 33 LiOH.H ₂ O, Ni (OH) _2, and LiF were mixed at a molar ratio of 0.9: 0.9: 0.2, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, baked at 650 ° C. for 20 hours and pulverized in an agate mortar, whereby the composition formula is Li
Particles containing lithium-containing nickel oxide represented by _1.1 Ni _0.9 O _1.83 F _0.17 as a main component and having an average particle diameter of 8.5 μm were produced. A positive electrode was produced in the same manner as in Example 1 except that the obtained particles were used. This positive electrode and Example 1
Using the same negative electrode, reference electrode and non-aqueous electrolyte as described above, the positive electrode evaluation battery shown in FIG. 5 was assembled.

The obtained Examples 44 to 47 and Comparative Example 33
Was charged at a current value of 1 mA until it reached 4.2 V, the current was stopped for 30 minutes, and then the battery was discharged at a current value of 1 m.
The cycle is repeated until the voltage reaches 3.0 V at A, and the current is stopped again for 30 minutes. The change in the discharge capacity according to the number of cycles is measured. Table 9 also shows the initial charge capacity and the discharge capacity at the 100th cycle of the battery of Example 12.

[0260]

[Table 9]

As apparent from Table 9, Examples 12 and 4
It can be seen that the batteries Nos. 4 to 47 have a longer charge / discharge cycle life than Comparative Example 33. In particular, Examples 12 and 45 in which the thickness of the film containing LiCoO ₂ as a main component is 20 to 50 nm,
It can be seen that the battery of No. 46 has better cycle characteristics than the batteries of Examples 44 and 47.

Example 48 <Preparation of Positive Electrode> LiOH.H ₂ O, Ni (OH) ₂ and L
mixing iF in a molar ratio of 0.96: 0.92: 0.12,
After holding at 550 ° C. for 5 hours in one atmosphere of pure water oxygen, 6
The particles were baked at 50 ° C. for 20 hours and pulverized in an agate mortar to produce particles containing lithium-containing nickel oxide as a main component represented by a composition formula of Li _1.08 Ni _0.92 O _1.9 F _0.1 . The average particle size of the obtained particles was 8.5 μm.

The obtained particles, acetylene black, polyvinylidene fluoride and N-methyl 2-pyrrolidone were mixed at a weight ratio of 85: 5: 10: 90, and then dispersed to prepare a slurry. The slurry was applied to an aluminum substrate having a thickness of 20 μm, dried at 150 ° C., and pressed by a roll press to obtain a thickness of 200 μm.
Was produced.

<Preparation of Negative Electrode> Mesophase carbon fiber, polyvinylidene fluoride and N-methyl 2-pyrrolidone were mixed at a weight ratio of 300: 24: 216 and dispersed to prepare a slurry. The slurry is 20 μm thick.
Was dried at 150 ° C. and pressed by a roll press machine to produce a negative electrode having a thickness of 200 μm.

After laminating the positive electrode, the separator made of a porous film made of polyethylene, and the negative electrode in this order, they were spirally wound so that the negative electrode was located outside, thereby producing an electrode group.

<Preparation of Electrolyte Solution> Lithium hexafluorophosphate (LiPF ₆ ) was added to a mixed solvent of ethylene carbonate and ethyl methyl carbonate (mixing volume ratio 1: 1).
A non-aqueous electrolyte was prepared by dissolving at a molar ratio of 1: 1.

The electrode group and the electrolytic solution were housed in stainless steel bottomed cylindrical containers, respectively, and had the structure shown in FIG. 1 described above, and had a diameter of 18 mm and a height of 65 mm. An electrolyte secondary battery was assembled.

Example 49 By a method similar to that in Example 48, the composition formula was Li _1.08 Ni
Particles having a mean particle size of 8.5 μm containing a lithium-containing nickel oxide represented by _0.92 O _1.9 F _0.1 as a main component were produced. On the other hand, a 1 mol / l film forming aqueous solution comprising lithium nitrate and cobalt nitrate was prepared. The molar ratio of lithium and cobalt contained in this aqueous solution was 1: 1. 5 mol of the aqueous solution is added to 1 mol of the particles, and the solution is sufficiently impregnated into the particles. The particles are baked at 550 ° C. for 20 hours in 1 atm of pure water oxygen to thereby epitaxially grow the entire surface of the particles. LiCo
A film containing O ₂ as a main component (having a thickness of 10 nm) was formed.
LiCoO ₂ of the film has a c-axis orientation of the Li _1.08 N
It had the same crystal structure as the direction of the c-axis of i _0.92 O _1.9 F _0.1 .

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using the positive electrode, the negative electrode, the separator, and the non-aqueous electrolyte similar to those in Example 48, the above-described non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled.

Comparative Example 34 LiOH.H ₂ O and Ni (OH) ₂ in a molar ratio of 1.02
After mixing at 5: 1 and maintaining at 550 ° C. for 5 hours in 1 atm of pure water oxygen, the mixture was calcined at 650 ° C. for 20 hours and pulverized in an agate mortar to obtain a composition formula of Li _1.025 Ni _0.975 O
Particles having a mean particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by ₂ as a main component were produced.

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using the positive electrode, the negative electrode, the separator, and the non-aqueous electrolyte similar to those in Example 48, the above-described non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled.

Comparative Example 35 LiOH.H ₂ O, Ni (OH) ₂ and LiF were mixed at a molar ratio of 0.75: 0.9: 0.35, and the mixture was heated at 550 ° C. for 5 hours in one atmosphere of pure water and oxygen. After holding, the mixture was baked at 650 ° C. for 20 hours, and crushed in an agate mortar, whereby the composition formula was L.
Particles having an average particle size of 8.5 μm and containing a lithium-containing nickel oxide represented by i _1.1 Ni _0.9 O _1.7 F _0.3 as a main component were produced.

A positive electrode was produced in the same manner as in Example 1, except that the particles thus obtained were used. Using the positive electrode, the negative electrode, the separator, and the non-aqueous electrolyte similar to those in Example 48, the above-described non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled.

The obtained Examples 48 to 49 and Comparative Example 34
After charging the batteries of ~ 35 at a current value of 1000 mA until reaching 4.2 V, the batteries were charged in a constant voltage mode for 30 minutes,
Next, discharge was performed at a current value of 1000 mA until the voltage reached 2.7 V, and a cycle of stopping the current for 30 minutes was repeated. Changes in the discharge capacity according to the number of cycles were measured, and the initial charge capacity and the discharge capacity at the 300th cycle were calculated as follows. It is shown in Table 10.

[0275]

[Table 10]

As is clear from Table 10, Examples 48 to
It can be seen that the secondary battery of No. 49 has excellent both initial capacity and cycle life. In contrast, the secondary battery of Comparative Example 34 has a high initial capacity but a short cycle life. Further, it can be seen that the secondary battery of Comparative Example 35 is inferior in both the initial capacity and the cycle life.

[0277]

As described above, according to the present invention,
A non-aqueous electrolyte secondary battery with improved discharge capacity and cycle life and a method for manufacturing the same can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a non-aqueous electrolyte secondary battery according to the present invention.

FIG. 2 is a characteristic diagram showing a relationship between x and y in a composition formula of a lithium-containing nickel oxide contained in a nonaqueous electrolyte secondary battery according to the present invention.

FIG. 3 shows x and y in the composition formula of lithium-containing nickel oxide contained in another nonaqueous electrolyte secondary battery according to the present invention.
FIG.

FIG. 4 is a characteristic diagram showing a composition of a lithium-containing nickel oxide included in the batteries of Examples 1 to 9, 37, 39, and 48 of the present invention.

FIG. 5 is a schematic diagram showing a positive electrode evaluation battery used in Examples 1 to 47 of the present invention.

FIG. 6 is a characteristic diagram showing the relationship between the number of cycles and the discharge capacity in the battery of Example 1 of the present invention.

FIG. 7 shows Examples 10 to 36, 38, 44 to 4 of the present invention.
7 is a characteristic diagram showing the composition of a lithium-containing nickel oxide included in the batteries of Nos. 7 and 49.

FIG. 8 is a characteristic diagram showing the relationship between the number of cycles and the discharge capacity in the batteries of Examples 40 to 43 of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... container, 3 ... electrode group, 4 ... positive electrode, 5 ... separator, 6
... negative electrode, 8 ... sealing plate.

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Shinji Arai 72 Horikawa-cho, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Inside the Toshiba Kawasaki Office (72) Inventor Motoki Kanda 72 Horikawacho, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Stock Company (56) References JP-A-7-153466 (JP, A) JP-A-4-237970 (JP, A) JP-A 8-195200 (JP, A) JP-A 9-147867 (JP) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H01M 4/58 H01M 4/02 H01M 10/40

Claims (5)

(57) [Claims] A positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the positive electrode includes a lithium-containing nickel oxide represented by a composition formula of Li _{1 + x} Ni _1-x O _uy F _y , X, y, and u satisfy the following expressions (1) to (3): (y + 0.05) / 2 ≦ x <(y + 1) / 3 (1) y> 0 (2) 1 .9 ≦ u ≦ 2.1 (3) A non-aqueous electrolyte secondary battery characterized by the following: 2. A method for manufacturing a non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the method is selected from lithium hydroxide, lithium oxide, lithium carbonate, and lithium nitrate. The molar ratio of at least one compound, at least one compound selected from nickel hydroxide, nickel oxide, nickel carbonate and nickel nitrate, and lithium fluoride is 0.85 to 1.
0: 0.8 to 0.95: mixing at 0.05 to 0.35; 550 ° C. to 6 at 550 ° C. in an oxygen atmosphere.
Step of maintaining at 00 ° C; 600 ° C to 6 in an oxygen atmosphere
Baking at 80 ° C .; producing the positive electrode by a method comprising: baking at 80 ° C. 3. A positive electrode comprising particles containing lithium-containing nickel oxide as a main component and a film containing lithium-containing oxide as a main component formed on at least a part of the particle surface;
A negative electrode and a non-aqueous electrolyte, wherein the lithium-containing nickel oxide has a composition formula of Li _{1 + x} N
i _1-x O _uy F _y, where x, y and u
Satisfies the following equations (4) to (7); y / 2 ≦ x <(y + 1) / 3 (4) y> 0 (5) x ≧ 0.05 (6) 9 ≦ u ≦ 2.1 (7) The lithium-containing oxide has a composition formula of LiMO ₂ (where M is at least one kind selected from Al, Co, Ni, Li, Mn, Ga and Ru). A non-aqueous electrolyte secondary battery characterized by being represented by the following formula: 4. The non-aqueous electrolysis according to claim 3, wherein the film containing lithium-containing oxide as a main component is formed on at least a part of the surface of the particles containing lithium-containing nickel oxide as a main component by epitaxial growth. Liquid secondary battery. 5. A method for producing a non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the method is selected from lithium hydroxide, lithium oxide, lithium carbonate and lithium nitrate. The molar ratio of at least one compound, at least one compound selected from nickel hydroxide, nickel oxide, nickel carbonate and nickel nitrate, and lithium fluoride is 0.85 to 1.
0: 0.8 to 0.95: mixing at 0.05 to 0.35; 550 ° C. to 6 at 550 ° C. in an oxygen atmosphere.
Step of maintaining at 00 ° C; 600 ° C to 6 in an oxygen atmosphere
Baking the particles at 80 ° C. to produce particles; an aqueous solution containing either a lithium nitrate or a lithium organic acid salt and either the element M nitrate or the element M organic acid salt is mixed with the aqueous solution. Impregnating the particles, wherein M is at least one selected from the group consisting of Al, Co, Ni, Li, Mn, Ga and Ru;
Baking at a temperature of from 00 to 600 ° C .; and producing the positive electrode by a method comprising: