JP2000302451A - Positive electrode active substance for lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve initial efficiency and recycle characteristic in charging and discharging by including a Li complex oxide comprising Li, Ni3+, Co, Al, Mn, B and O and having a specific composition in which a part of Ni is substituted with Co, Al, Mn, etc. SOLUTION: This positive electrode active substance for nonaqueous electrolyte lithium ion secondary battery comprises a lithium nickel-based complex oxide represented by the formula LiyNi3+1-xM3+xO2-(2a-3)b/2(BOa)(2a-3)-b (M is Co, Al or Mn; 0.9<=y<=1.1, 0.1<x<=0.4, 1.5<a<4 and 0.005<=b<=0.05) as an active ingredient. The complex oxide is obtained by adding prescribed amount of Li and B compounds to a basic metal salt represented by the formula Ni2+(1-x) Mp+x(OH)2-2x+px-nzAzn-.mH2O [p is a valence of M, An- is an n-valent anion and n is 1-3; 0.03<=z<=0.3; 0<=m<=2], drying the resultant slurry by spray dry or freeze dry and then baking the dried material at about 600-900 deg.C for about >=4 hr under oxidative atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive electrode active material for a lithium ion secondary battery having improved initial efficiency and cycle characteristics during charge and discharge, a method for producing the same, and a positive electrode comprising the positive electrode active material as an active ingredient. The present invention relates to a non-aqueous electrolyte lithium ion secondary battery as a component.

[0002]

2. Description of the Related Art In recent years, with the miniaturization and portability of electronic devices,
Instead of nickel / cadmium and nickel metal hydride batteries
Lithium ion batteries
The demand for secondary batteries is increasing. This lithium ion secondary
Lithium ion is used as the positive electrode active material of the battery.
Layering that can be calated and deintercalated
LiNiO compound_Two, LiCoO_TwoIs known,
Among them, LiCoO_TwoIs positive for lithium ion secondary batteries
Used as a polar active material. However, LiCoO _Two
, A raw material for coal, is expensive and rare metal is supplied
LiNiO, less expensive and resource-rich, limited in quantity_TwoWhat
Alternatives are being considered. However, LiNiO_TwoIs
LiCoO_TwoHigher electric capacity but unstable structure
As a result, structural changes occur as charging and discharging progress,
There are problems with cyclability, charge / discharge efficiency, and the like.

As a countermeasure, the following formula (I) in which a part of nickel is replaced with cobalt, aluminum, boron or the like to form a solid solution.
II) Li _y [Ni ³⁺ _{(1 - x)} M ³⁺ _x ] O ₂ (III) (where M ³⁺ is cobalt, aluminum or boron)
(Japanese Patent Laid-Open No. 6-275)
No. 275, JP-A-8-45509, JP-A-8-780
06). However, even with this proposal, LiCoO ₂
The above performance has not been achieved yet.

[0004]

SUMMARY OF THE INVENTION The present inventors have proposed LiNi
As a result of intensive studies on the improvement of the charge / discharge cycle property and charge / discharge efficiency of O ₂ , a part of nickel was changed to cobalt or cobalt and aluminum having a smaller ion radius than nickel.
When a solid solution is substituted with a valent metal, the interlayer distance is reduced in proportion to the amount of the solid solution, and the structure is stabilized accordingly, and when the amount of the solid solution is replaced by at least about 20 mol% of nickel, there is no structural change during charge and discharge. I found that. As a result, the solid solution obtained by substituting about 20 mol% or more of nickel with cobalt or cobalt and aluminum has come close to the battery performance of LiCoO ₂ . However, it still does not reach the level equivalent to LiCoO ₂ . In addition, boron (B) having an ionic radius smaller than that of nickel was added to LiNiO ₂ together with cobalt or cobalt and aluminum, and a solid solution was formed. .

[0005]

SUMMARY OF THE INVENTION The inventors of the present invention did not substitute boron for nickel metal, but instead used a oxyacid anion of boron to form Li.
A general formula (I) Li _y Ni ³⁺ _(1-x) M ³⁺ _x O _{[2- (2a-3) b / 2]} (in which a part of oxygen near the crystal surface of NiO ₂ is substituted and dissolved ₎ By using BO _a ) ^(2a-3) _-b (I), the battery performance is improved as compared with the solid solution of the formula (III) in which a part of nickel is substituted by cobalt or cobalt and aluminum, and LiCoO ₂ Has been found to be an alternative. The reason is that the borate ion replaces a part of the oxygen anion layer on the crystal surface with borate ion, thereby expanding the interlayer on the crystal surface and facilitating the insertion and desorption of lithium ions. It is considered that the battery performance was improved as a result.

[0006] The spread between the layers was measured by a powder X-ray diffractometer using Cu-Kα radiation of the obtained material.
It has a crystal structure equivalent to NiO ₂ and its lattice constant C.
You can see from the spread. Boron ions have an ionic radius smaller than that of nickel, and the interlayer becomes narrower when substituted solid solution with nickel. However, in the present invention, since a part of the oxygen anion layer on the crystal surface is replaced with borate anions, the ionic radius of the borate anions is reduced. Since it is larger than oxygen, the layers spread in reverse.

[0007] Because of the above structural features, the desorption / insertion of lithium ions is facilitated, the voltage at the start of charging in the charge / discharge curve is reduced, the capacity is increased, and the initial efficiency is improved.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a positive electrode active material for a lithium ion secondary battery according to the present invention will be specifically described.

The positive electrode active material for a lithium ion secondary battery according to the present invention has a general formula (I): Li _y Ni ³⁺ _(1-x) M ³⁺ _x O _{[2- (2a-3) b / 2]} ( BO _a ) ^(2a-3) _-b (I) (wherein, M is at least one metal selected from Co, Al and Mn, and y, x, a and b are in the following ranges, respectively) , Y is 0.9 ≦ y ≦ 1.1, x is 0.1 <
x ≦ 0.4, a is 1.5 <a <4, b is 0.005 ≦ b
The positive electrode active material for a non-aqueous electrolyte lithium-ion secondary battery contains a lithium-nickel-based composite oxide represented by the following formula:

In the general formula (I), Li _y Ni ³⁺ _(1-x) Co ³⁺ _x O _{[2- (2a-3) b / 2]} (BO _a )
^(2a-3) _-b (where y, x, a, and b are in the following ranges, y is 0.9 ≦ y ≦ 1.1, x is 0.1 <x ≦ 0.4, a Is a positive number satisfying 1.5 <a <4, and b is a positive number satisfying 0.005 ≦ b ≦ 0.05) is a positive electrode active material for a non-aqueous electrolyte lithium ion secondary battery.

In the above general formula (I), Li _y Ni ³⁺ _(1-x) (Co, Al) ³⁺ _x O
_{[2- (2a-3) b / 2]} (BO _a ) ^(2a-3) _-b (where y, x, a and b are in the following ranges, respectively, and y is 0.9 ≦ y ≦ 1) .1, x is 0.1 <x ≦ 0.4, a is 1.5 <a <4, and b is a positive number satisfying 0.005 ≦ b ≦ 0.05). It is a positive electrode active material for a liquid lithium ion secondary battery.

Further, in the general formula (I), Li _y Ni ³⁺ _(1-x) (Co, Al, Mn) ³⁺ _x O
_{[2- (2a-3) b / 2]} (BO _a ) ^(2a-3) _-b (where y, x, a and b are in the following ranges, respectively, and y is 0.9 ≦ y ≦ 1) .1, x is 0.1 <x ≦ 0.4, a is 1.5 <a <4, and b is a positive number satisfying 0.005 ≦ b ≦ 0.05). It is a positive electrode active material for a liquid lithium ion secondary battery.

The lithium nickel composite oxide of the present invention can be obtained by the following production method. Specifically, the general formula (I) Li _y Ni ³⁺ _(1-x) M ³⁺ _x O _{[2- (2a-3) b / 2]} (BO _a ) ^(2a-3) _-b (I (Wherein, M is at least one metal selected from Co, Al and Mn, y, x, a and b are in the following ranges, respectively, and y is 0.9 ≦ y ≦ 1.1, x Is 0.1 <x ≦
0.4, a is 1.5 <a <4, b is 0.005 ≦ b ≦
In the lithium nickel composite oxide represented by a positive indicates the number of) that satisfies the 0.05, the general formula _{^{(II) Ni 2+ (1-}} x) M P + x (OH) (2-2x + px-nz ^{_{) (a n-) z · mH}} 2 O (II) ( wherein, p is the valence of M, a ^n-n-valent (n =. 1 to
3) The anion, z and m are each 0.03 ≦ z ≦
0.3, a positive number that satisfies the range of 0 ≦ m <2) to a basic metal salt represented by the formula (1): In a water medium, an amount of a lithium compound corresponding to the number of moles of lithium atom represented by y is further added in an aqueous medium.
It can be manufactured by firing at 00 ° C. for about 4 hours or more.

Further, an amount of a lithium compound corresponding to the number of moles of lithium atom represented by y in the general formula (I) is added to the basic metal salt represented by the general formula (II) in an aqueous medium to obtain a slurry. After spraying or freeze-drying, is further treated with the general formula (I)
B) dry mixing a boron compound in an amount corresponding to the number of moles of boron atoms shown in b, and under an oxidizing atmosphere at about 600 to 900 ° C.
It can be manufactured by firing for about 4 hours or more.

Further, an amount of a lithium compound corresponding to the number of moles of lithium atom represented by y in the general formula (I) is added to the basic metal salt represented by the general formula (II) in an aqueous medium, and the resulting slurry is obtained. Is sprayed or freeze-dried, and then calcined in an oxidizing atmosphere at about 600 to 900 ° C. for about 4 hours or more. After pulverization or pulverization, an amount of boron compound corresponding to the number of moles of boron atoms represented by b in the general formula (I) is obtained. It can be manufactured by dry mixing and firing again at about 600 to 900 ° C. for about 2 hours or more in an oxidizing atmosphere.

A feature of the above manufacturing process is that a borate is added later to a basic metal salt in which M is dissolved in nickel in advance. Therefore, boron substitution does not occur in the nickel layer, and after the firing reaction, a part of the oxygen anion on the crystal surface is substituted with a borate anion as a borate anion.

In the method for producing a basic metal salt, A ^n- is, for example, NO ₃ ⁻ , Cl ⁻ , B
r ^-, CH ₃ COO ^-, it can be selected from anions represented by CO ₃ ^2- or the like.

The basic metal salt used here is Ni ²⁺
About 0.7 to 1.0 equivalent, preferably about 0.8 to 0.95 equivalent of an alkali is added to the aqueous solution of _(1-x) MP ⁺ _x salt under a reaction condition of about 80 ° C. or less. It can be produced by reacting. Examples of the alkali used here include hydroxides of alkali metals such as sodium hydroxide, hydroxides of alkaline earth metals such as calcium hydroxide, and amines. It is more preferable that the basic metal salt is aged at 20 to 70 ° C. for 0.1 to 10 hours after the synthesis. Next, by-products are removed by washing with water to obtain a basic metal salt slurry.

As the lithium compound, for example, LiO
One or more of H, LiNO ₃ , Li ₂ CO _3, or a hydrate thereof can be selected.

As the boron compound, H ₃ BO ₃ , Li ₂
B ₄ O _{7 and the} like can be suitably used.

The slurry obtained by such a reaction is preferably dried by spraying or freeze-drying.

The spray drying method, which can be dried instantaneously and can obtain a spherical product, has a spherical granulation property and a uniform composition (in a drying method requiring a long drying time, lithium is transferred to the surface, resulting in an uneven composition). This is preferable from the viewpoint of the product and is practical.

The calcination is carried out at 600 to 900 ° C., preferably at 7 ° C.
Performed in a temperature range of 50 to 800 ° C. under an oxygen atmosphere for about 4
It is carried out for more than an hour, preferably for 4 to 72 hours. Firing time 7
If it is more than 2 hours, it will not only increase the cost,
With the volatilization of lithium, it becomes poor in purity.

According to the technique relating to the calcination, it is considered that the calcination for at least 20 hours or more is required for nickel, which is difficult to become divalent to trivalent by a known technique such as a dry method. The compound can be obtained very economically by a simple production method.

In order to increase the bulk density, a press molding method is advantageous. In the press molding method, after spraying or freeze-drying the slurry obtained in the above-mentioned production process of the present invention, the slurry is press-molded, and calcined in an oxidizing atmosphere at about 600 to 900 ° C. for about 4 hours or more, and represented by the general formula (I). This is a method for producing a lithium nickel-based composite oxide.

For example, a composite oxide having a high bulk density, a high crystallinity and a high purity can be obtained by press-molding a spray-dried product obtained by the above-mentioned spray-drying method and in which a small amount of the solid solution is uniformly dissolved. .

The spherical product, which is a spray-dried product, is a powder having excellent fluidity, moldability, and filling properties, and can be directly press-molded according to a conventional method.

The molding pressure varies depending on the press, the charged amount and the like, and is not particularly limited.
About 000 kg / cm ² is preferable. The press molding machine can be suitably used, such as a tableting machine, a briquette machine, and a roller compactor, but is not particularly limited as long as it can be pressed.

The density of the pressed product is preferably 1 to 4 g / cc, more preferably about 2 to 3 g / cc.

[0030] Press molding is extremely useful in that the distance of movement between crystal grains is reduced and crystal growth during firing is promoted. Therefore, the material to be subjected to press molding does not necessarily need to be a spray-dried spherical product, and a freeze-dried product can also be used.

This press-formed product is fired as it is. The firing temperature is usually 600 to 900 ° C., preferably 7
The reaction is performed at 50 to 800 ° C. in an oxygen stream for 4 hours or more. The longer the firing time, the larger the primary particles, so the firing time is determined by the desired size of the primary particles.

The non-aqueous electrolyte lithium ion secondary battery of the present invention comprises a positive electrode containing a positive electrode active material, a negative electrode capable of doping and undoping lithium, and a non-aqueous solution obtained by dissolving or dispersing a lithium salt in a non-aqueous medium. In a non-aqueous electrolyte lithium ion secondary battery comprising an aqueous electrolyte, the positive electrode active material is represented by the general formula (I): Li _y Ni ³⁺ _(1-x) M ³⁺ _x O _{[2- (2a-3) b / 2]} (BO _a ) ^(2a-3) _-b (I) (wherein, M is at least one metal selected from Co, Al and Mn, and y, x, a and b are each In the following range, y is 0.9 ≦ y ≦ 1.1 and x is 0.1 <
x ≦ 0.4, a is 1.5 <a <4, b is 0.005 ≦ b
A positive number satisfying ≦ 0.05).

As a method for producing a positive electrode using the positive electrode active material, for example, powder of the positive electrode active material,
For example, a conductive material such as carbon black or graphite, and a binder resin such as polyvinylidene fluoride are uniformly mixed to prepare a positive electrode mixture composition, and compression-molded to form a pellet shape for a coin-type secondary battery. A positive electrode can be manufactured.

Further, in addition to the powder of the positive electrode active material, the conductive material and the binder resin, a known solvent, for example, a solvent such as formamide or N-methylpyrrolidone is added to prepare a paste-like positive electrode mixture. Then, by applying it to a positive electrode current collector and drying it, a positive electrode for a cylindrical or prismatic secondary battery can be manufactured.

The positive electrode comprises a negative electrode made of a material capable of doping and undoping lithium, for example, a carbonaceous material or a lithium alloy, and a nonaqueous electrolyte solution made of a nonaqueous electrolyte solution in which a lithium salt is dissolved. It can be suitably used in a secondary battery. Examples of the material capable of doping and undoping lithium include, for example, pyrolytic carbons, pitch coke, petroleum coke, cokes such as needle coke, graphites, glassy carbons, phenol resins, and furan resins. An organic polymer compound fired body fired at a temperature, a carbonaceous material such as carbon fiber or activated carbon, or a polymer such as polyacetylene or polypyrrole can be used. As the lithium alloy, for example, a lithium-aluminum alloy or the like can be used.

The non-aqueous electrolyte lithium-ion secondary battery comprising the positive electrode containing the positive electrode active material of the present invention as an active ingredient and obtained by the above-mentioned production method, comprises the following negative electrode, non-aqueous electrolyte,
It can be produced by appropriately combining with a non-aqueous solvent, an electrolyte and the like.

For example, when a carbonaceous material is used as the negative electrode, the same treatment as in the case of producing the positive electrode is performed. For example, a powder of the carbonaceous material and a binder resin such as polyvinylidene fluoride are uniformly mixed. Thus, a negative electrode mixture composition is prepared, and the resultant is compression-molded, whereby a pellet-shaped negative electrode for a coin-type secondary battery can be produced. When using metallic lithium or lithium alloy as the negative electrode material, plate-shaped metallic lithium or lithium alloy must be
A negative electrode can be produced by mechanically punching (for example, a pellet shape).

As the non-aqueous electrolyte, a non-aqueous electrolyte or a solid electrolyte obtained by dissolving or dispersing a lithium salt electrolyte in a known non-aqueous medium (such as a non-aqueous solvent or an ionic conductive polymer) can be used. .

The non-aqueous solvent of the non-aqueous electrolyte includes propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, γ-butyl lactone, sulfolane, 1,2-dimethoxyethane, 1,2-
Diethoxyethane, 2-methyltetrahydrofuran, 3
-Methyl-1,3-dioxolane, methyl propionate, methyl butyrate, dimethinolecarbonate, diethyl carbonate, dipropyl carbonate and the like can be used. The above solvents may be used alone or in combination of two or more.

As the electrolyte, for example, LiClO ₄ ,
LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiCF ₃ S
O ₃ and LiN (CF ₃ SO ₂ ) can be used. Other configurations of the non-aqueous electrolyte secondary battery, for example, a separator, a battery can, and the like can be the same as the conventional non-aqueous electrolyte secondary battery, and are not particularly limited. Also, the shape of the battery is not particularly limited, and may be any shape such as a cylindrical shape, a square shape, a coin shape, and a button shape.

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

[0042]

【Example】

Example 1 A mixed aqueous solution having a total molar number of (Ni + Co) of 4.0 M was prepared using nickel nitrate and cobalt nitrate so that the molar ratio of Ni: Co was 80:20. Further 4.0
M sodium hydroxide solution was prepared, and both aqueous solutions were simultaneously added to a reaction vessel with stirring using a metering pump so as to have a pH of 9.5, and a continuous reaction was performed at a reaction temperature of 25 ° C. and a residence time of 15 minutes. Was. The obtained reaction product was filtered and washed with water (the composition of a partially dried product was Ni ²⁺ _0.8 Co ²⁺ _0.2 (O 2
H) _1.843 (NO ₃ ) _0.157 · 0.16 H ₂ O), after suspending in water, an amount of 3.0 M lithium hydroxide corresponding to a molar ratio of Li / (Ni + Co) = 1.02 An aqueous solution was added, and an aqueous solution of lithium tetraborate in an amount corresponding to (Ni + Co): B molar ratio = 100: 1 was added to form a slurry, and spray drying was performed. The obtained dried gel is put in an alumina boat and a tubular furnace (TF-630 type manufactured by Yamada Denki)
For 15 hours in the range of 750 to 800 ° C. in an oxygen flow to obtain a lithium nickel composite oxide. Then, Teflon were mixed so as to 70:20:10 at a weight ratio of acetylene black and a binder as a conductive agent with respect to the lithium nickel composite oxide, the diameter of this Seikyokuzai 75mg at 3 t / cm ² It was pressed into a pellet of 18 mm, punched out to a diameter of 16 mm, dried sufficiently, and used as a positive electrode. FIG. 1 is a cross-sectional view of a battery manufactured using the electrodes prepared as described above. The positive electrode 7 was assembled into a 2032 type coin battery in a glove box under an argon atmosphere. A lithium metal having a diameter of 15 mm and a thickness of 1 mm was used for the negative electrode 2, and a 1: 2 mixed solution of ethylene carbonate (EC) and dimethyl carbonate (DMC) using 1 mol of LiPF ₆ as a supporting salt was used for the electrolyte. . For the battery prepared as described above, 3.0V to 4.3V
A charge / discharge test was performed at a current density of 0.4 mA / cm ² in the battery range of No. 1.

COMPARATIVE EXAMPLE 1 Nickel nitrate, cobalt nitrate and boric acid were used so that the molar ratio of Ni: Co: B = 80: 20: 1 (Ni + C
A mixed aqueous solution in which the total number of moles of o + B) was 4.0 M was prepared. Further, a 4.0 M sodium hydroxide solution was prepared, and both aqueous solutions were stirred with a metering pump, and the pH was added to the reaction vessel.
Simultaneous addition was carried out to 9.5, and the reaction temperature was 25 ° C.
A continuous reaction was performed with a residence time of 15 minutes. The obtained reaction product was filtered, washed with water, suspended in water, and then Li / (Ni +
Co + B) = 3.0 M in an amount corresponding to a molar ratio of 1.03
Of lithium hydroxide was added to form a slurry, and spray drying was performed. The obtained dried gel is placed in an alumina boat, and calcined in a tubular furnace (TF-630 type manufactured by Yamada Electric Co., Ltd.) at 750 to 800 ° C. for 15 hours under an oxygen flow.
A lithium nickel composite oxide was obtained.

Example 2 A mixed aqueous solution in which the total number of moles of (Ni + Co + Al) was 4.0 M using nickel nitrate, cobalt nitrate and aluminum nitrate so that the molar ratio of Ni: Co: Al was 80: 15: 5. It was prepared and operated in the same manner as in Example 1 to obtain a fired product. The composition of the partially dried product of the reaction product obtained on the way was Ni ²⁺ _0.8 Co ²⁺ _0.15 Al ³⁺ _0.05 (O
H) _1.852 (NO ₃ ) _0.198 · 0.19 H ₂ O. Further, a battery was manufactured in the same manner as in Example 1, and a charge / discharge test was performed under the same conditions.

Comparative Example 2 The total number of moles of (Ni + Co + Al + B) was 4. using nickel nitrate, cobalt nitrate, aluminum nitrate and boric acid so that the molar ratio of Ni: Co: Al: B = 80: 15: 5: 1. A mixed aqueous solution of 0 M was prepared, and the operation was performed in the same manner as in Comparative Example 1 to obtain a fired product. Further, a battery was manufactured in the same manner as in Example 1, and a charge / discharge test was performed under the same conditions.

Example 3 Using nickel nitrate, cobalt nitrate, aluminum nitrate and manganese nitrate so that the molar ratio of Ni: Co: Al: Mn = 80: 10: 5: 5 (Ni + Co + Al + M)
preparing a mixed aqueous solution in which the total number of moles of n) is 4.0 M;
Thereafter, the same operation as in Example 1 was performed to obtain a fired product. The partially dried product of the reaction product obtained on the way had a composition of Ni
²⁺ _0.8 Co ²⁺ _0.1 Al ³⁺ _0.05 Mn ²⁺ _0.05 (OH)
_1.815 (NO ₃ ) _0.235 · 0.22 H ₂ . further,
A battery was manufactured in the same manner as in Example 1, and a charge / discharge test was performed under the same conditions.

Comparative Example 3 Ni: Co: Al: Mn: B molar ratio = 80: 10: 5:
Using nickel nitrate, cobalt nitrate, aluminum nitrate, manganese nitrate and boric acid so that the ratio becomes 5: 1 (Ni +
A mixed aqueous solution in which the total number of moles of (Co + Al + Mn + B) was 4.0 M was prepared, and the operation was performed in the same manner as in Comparative Example 1 to obtain a fired product. Further, a battery was manufactured in the same manner as in Example 1, and a charge / discharge test was performed under the same conditions.

X-ray diffraction measurements were performed on the fired products obtained in each of the examples and comparative examples. The result is shown in FIG. The obtained X-ray diffraction patterns were obtained from Joint com.
mittee onpowder diffracti
on standards (hereinafter referred to as JCPDS)
Has the same crystal structure as LiNiO ₂ registered in No. 09-0063.

Next, the lattice constant was calculated from the obtained X-ray diffraction pattern, and the results are shown in Table 1.

[Table 1]

In Examples 1, 2, and 3 in which part of the oxygen anion layer on the crystal surface was replaced with borate anion, the lattice constant C was higher than that of the corresponding comparative example. It can be seen that the size of the layer increases and the interlayer spreads.

Next, as a result of examining the initial charge / discharge curve by the charge / discharge test (FIGS. 3, 4 and 5), the open circuit voltage at the start of the charge was higher in the example substituted with the borate anion than in the comparative example. This shows that the insertion and desorption of lithium ions are easy.

The initial discharge capacity, initial efficiency, and 30
The cycle retention was determined by the following equation and is shown in Table 2. In addition, initial efficiency = initial discharge capacity / initial charge capacity, and 30-cycle retention = discharge capacity at 30th cycle / initial discharge capacity.

[Table 2]

From the above results, it can be understood that the performance of the battery can be greatly improved by substituting a part of the oxygen anion layer on the crystal surface with the borate anion.

[0055]

According to the present invention, it is possible to provide a positive electrode active material for a non-aqueous electrolyte lithium ion secondary battery having improved charge / discharge cycle characteristics and charge efficiency as compared with LiNiO ₂ .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a lithium secondary battery according to an embodiment of the present invention.

FIG. 2 shows the XR of the compounds of Examples 1 to 3 and Comparative Examples 1 to 3.
D.

FIG. 3 is a charge / discharge curve of the compounds of Example 1 and Comparative Example 1.

FIG. 4 is a charge / discharge curve of the compounds of Example 2 and Comparative Example 2.

FIG. 5 is a charge / discharge curve of the compounds of Example 3 and Comparative Example 3.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeo Miyata 16-11 Shimohata-cho, Yawatanishi-ku, Kitakyushu-shi, Fukuoka F-term in Seawater Chemical Laboratory Co., Ltd. 4G048 AA04 AB05 AC06 AE05 5H003 AA02 AA04 BA00 BA01 BA03 BA04 BB05 BC01 BD00 BD01 5H029 AJ03 AJ05 AK03 AL06 AM03 AM04 AM05 AM07 BJ03 BJ16 CJ00 CJ02 CJ08 CJ28 DJ16 HJ00 HJ02 HJ14

Claims (9)

[Claims] 1. The formula (I): Li _y Ni ³⁺ _(1-x) M ³⁺ _x O _{[2- (2a-3) b / 2]} (BO _a ) ^(2a-3) _-b (I (Wherein, M is at least one metal selected from Co, Al and Mn, y, x, a and b are in the following ranges, respectively, and y is 0.9 ≦ y ≦ 1.1) , X is 0.1 <
x ≦ 0.4, a is 1.5 <a <4, b is 0.005 ≦ b
A positive electrode active material for a non-aqueous electrolyte lithium-ion secondary battery, characterized by containing a lithium-nickel-based composite oxide represented by the following formula: 2. In the above formula (I), Li _y Ni ³⁺ _(1-x) Co ³⁺ _x O _{[2- (2a-3) b / 2]} (BO _a )
^(2a-3) _-b (where y, x, a, and b are in the following ranges, y is 0.9 ≦ y ≦ 1.1, x is 0.1 <x ≦ 0.4, a Is a positive number satisfying 1.5 <a <4, and b is a positive number satisfying 0.005 ≦ b ≦ 0.05.) The positive electrode active material for a non-aqueous electrolyte lithium ion secondary battery according to claim 1. 3. The method according to claim 1, wherein Li _y Ni ³⁺ _(1-x) (Co, Al) ³⁺ _x O
_{[2- (2a-3) b / 2]} (BO _a ) ^(2a-3) _-b (where y, x, a and b are in the following ranges, respectively, and y is 0.9 ≦ y ≦ 1) .1, x is 0.1 <x ≦ 0.4, a is 1.5 <a <4, and b is a positive number satisfying 0.005 ≦ b ≦ 0.05). The positive electrode active material for a non-aqueous electrolyte lithium ion secondary battery according to the above. 4. In the above general formula (I), Li _y Ni ³⁺ _(1-x) (Co, Al, Mn) ³⁺ _x O
_{[2- (2a-3) b / 2]} (BO _a ) ^(2a-3) _-b (where y, x, a and b are in the following ranges, respectively, and y is 0.9 ≦ y ≦ 1) .1, x is 0.1 <x ≦ 0.4, a is 1.5 <a <4, and b is a positive number satisfying 0.005 ≦ b ≦ 0.05). The positive electrode active material for a non-aqueous electrolyte lithium ion secondary battery according to the above. 5. The formula (I): Li _y Ni ³⁺ _(1-x) M ³⁺ _x O _{[2- (2a-3) b / 2]} (BO _a ) ^(2a-3) _-b (I (Wherein, M is at least one metal selected from Co, Al and Mn, y, x, a and b are in the following ranges, respectively, and y is 0.9 ≦ y ≦ 1.1) , X is 0.1 <
x ≦ 0.4, a is 1.5 <a <4, b is 0.005 ≦ b
In the lithium nickel composite oxide represented by ≦ 0.05 indicates a positive number satisfying), general formula _{^{(II) Ni 2+ (1-}} x) M P + x (OH) (2-2x + px ^{_{-nz) (a n-) z ·}} mH 2 O (II) ( wherein, p is the valence of M, a ^n-n-valent (n =. 1 to
3) The anion, z and m are each 0.03 ≦ z ≦
0.3, a positive number that satisfies the range of 0 ≦ m <2) to a basic metal salt represented by the formula (I): In a water medium, an amount of boron compound corresponding to the number of moles of boron atoms shown in b is further added in an aqueous medium.
A production method characterized by firing at 00 ° C. for about 4 hours or more. 6. The formula (I): Li _y Ni ³⁺ _(1-x) M ³⁺ _x O _{[2- (2a-3) b / 2]} (BO _a ) ^(2a-3) _-b (I (Wherein, M is at least one metal selected from Co, Al and Mn, y, x, a and b are in the following ranges, respectively, and y is 0.9 ≦ y ≦ 1.1) , X is 0.1 <
x ≦ 0.4, a is 1.5 <a <4, b is 0.005 ≦ b
In the lithium nickel composite oxide represented by ≦ 0.05 indicates a positive number satisfying), general formula _{^{(II) Ni 2+ (1-}} x) M P + x (OH) (2-2x + px ^{_{-nz) (a n-) z ·}} mH 2 O (II) ( wherein, p is the valence of M, a ^n-n-valent (n =. 1 to
3) The anion, z and m are each 0.03 ≦ z ≦
0.3, a positive number that satisfies the range of 0 ≦ m <2) to a basic metal salt represented by the formula (I): The resulting slurry was sprayed or freeze-dried, and then dry-mixed with a boron compound in an amount corresponding to the number of moles of boron atom represented by b in the general formula (I).
A manufacturing method characterized by manufacturing by baking at 00 to 900 ° C. for about 4 hours or more. 7. The formula (I): Li _y Ni ³⁺ _(1-x) M ³⁺ _x O _{[2- (2a-3) b / 2]} (BO _a ) ^(2a-3) _-b (I (Wherein, M is at least one metal selected from Co, Al and Mn, y, x, a and b are in the following ranges, respectively, and y is 0.9 ≦ y ≦ 1.1) , X is 0.1 <
x ≦ 0.4, a is 1.5 <a <4, b is 0.005 ≦ b
In the lithium nickel composite oxide represented by ≦ 0.05 indicates a positive number satisfying), general formula _{^{(II) Ni 2+ (1-}} x) M P + x (OH) (2-2x + px ^{_{-nz) (a n-) z ·}} mH 2 O (II) ( wherein, p is the valence of M, a ^n-n-valent (n =. 1 to
3) The anion, z and m are each 0.03 ≦ z ≦
0.3, a positive number that satisfies the range of 0 ≦ m <2) to a basic metal salt represented by the formula (I): It is added in a medium, and the obtained slurry is sprayed or freeze-dried, and then calcined in an oxidizing atmosphere at about 600 to 900 ° C. for about 4 hours or more. A production method characterized in that a boron compound in an amount corresponding to the number of moles is dry-mixed and calcined again in an oxidizing atmosphere at about 600 to 900 ° C for about 2 hours or more. 8. The method according to claim 5, wherein the slurry obtained by spraying or freeze-drying the slurry obtained in claims 5, 6 and 7 is press-molded, and then calcined in an oxidizing atmosphere at about 600 to 900 ° C. for about 4 hours or more. Production method. 9. A non-aqueous electrolyte lithium ion secondary battery comprising a positive electrode comprising the positive electrode active material according to claim 1, 2, 3 or 4 as an active ingredient.