JP2001052744A - Nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte battery excellent in preservation characteristics, by keeping the electrolyte so as not to be decomposed by a positive electrode active material or a negative electrode active material even if it is preserved in a charged state. SOLUTION: This nonaqueous electrolyte battery 10 is equipped with a carbon material as a component material for a positive electrode collector, and a nonaqueous electrolyte containing at least one kind of electrolyte salt selected from lithium perfluoroalkyl sulfonic acid imide expressed by LiN (CmF2m+1SO2) (CnF2n+1SO2) [where (m) and (n) are independently integers from 1 through 4] or lithium perfluoroalkyl sulfonic acid methide expressed by LiC (CpF2p+1SO2) (CqF2q+1SO2) (CrF2f+1SO2) [where (p), (q) and (r) are independently integers from 1 through 4].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte battery comprising a positive electrode capable of inserting and removing lithium ions, a negative electrode capable of inserting and removing lithium ions, and a non-aqueous electrolyte. In particular, it relates to improvement of a non-aqueous electrolyte in which a positive electrode current collector and a lithium salt are dissolved.

[0002]

2. Description of the Related Art In recent years, lithium secondary batteries have come into practical use as small, lightweight, high-capacity, chargeable / dischargeable batteries, and portable electronic and communication equipment such as small video cameras, mobile phones, and notebook computers. And so on.
This type of lithium secondary battery uses a carbon-based material or lithium metal or lithium alloy capable of inserting and extracting lithium ions as a negative electrode active material, and uses LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , and Li as positive electrode active materials.
The battery comprises a lithium-containing transition metal oxide such as FeO ₂ and a nonaqueous electrolyte in which a lithium salt is dissolved as a solute in an organic solvent.

As a solvent for a non-aqueous electrolyte used in such a lithium secondary battery, ethylene carbonate (E
C), propylene carbonate (PC), vinylene carbonate (VC), butylene carbonate (BC), diethyl carbonate (DEC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC),
1,2-diethoxyethane (DEE), 1,2-dimethoxyethane (DME), ethoxymethoxyethane (EM
A single solvent such as E) or a mixed solvent of two or more components is used. Also, as a solute dissolved in this solvent,
LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiAs
F ₆ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ S
O ₂ ) ₃ , LiCF ₃ (CF ₂ ) ₃ SO _{3 and the} like are used.

[0004]

In such a lithium secondary battery, aluminum is generally used as a positive electrode current collector. By the way, when aluminum is used for the positive electrode current collector of the lithium secondary battery, the aluminum is corroded as the charge / discharge cycle progresses, and the charge / discharge cycle characteristics are remarkably deteriorated, resulting in a problem that the battery life is short. . In JP-A-10-125352, a carbon material or a resin film or a metal foil coated with a carbon material is used for a positive electrode current collector, and lithium perfluoroalkylsulfonate or lithium perfluoroalkylsulfonylamide is used as a nonaqueous electrolyte. Lithium secondary batteries used as solutes have been proposed. This prevents corrosion of the positive electrode current collector,
The cycle characteristics have been improved.

However, Japanese Patent Application Laid-Open No. H10-125352 discloses
Even in the lithium secondary battery proposed in the publication, a carbon material or a resin film or a metal foil coated with the carbon material serving as a positive electrode current collector is formed by using lithium perfluoroalkyl sulfonate or lithium perfluoroalkyl sulfonylamide as a solute. Since the non-aqueous electrolyte is in direct contact with the non-aqueous electrolyte, the solvent of the non-aqueous electrolyte decomposes during charging when the potential of the positive electrode becomes high. occured. Therefore, the present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a nonaqueous electrolyte battery having excellent charge storage characteristics by preventing the nonaqueous electrolyte from being decomposed even when stored in a charged state. It is in.

[0006]

[Means for solving the problems and their functions and effects]
In order to solve the above problems, the non-aqueous electrolyte battery of the present invention
In addition, a carbon material is provided as a constituent material of the positive electrode current collector.
And LiN (C_mF_{2m + 1}SO_Two) (C _nF_{2n + 1}S
O_Two(Where m and n are each independently 1 to 4 integers)
Lithium perfluoroalkyl sulfone represented by
Acid imide or LiC (C_pF_{2p + 1}SO_Two) (C_qF
_{2q + 1}SO_Two) (C_rF_{2r + 1}SO_Two) (However, p, q and
And r are each independently an integer of 1-4)
Selected from perfluoroalkylsulfonic acid methides
A non-aqueous electrolyte containing at least one electrolyte salt
I am trying to.

When at least one kind of electrolyte salt selected from lithium perfluoroalkylsulfonic acid imide or lithium perfluoroalkylsulfonic acid methide is provided and a carbon material is provided as a constituent material of the positive electrode current collector, Since a film (protective film) is formed on the surface of the positive electrode current collector, the non-aqueous electrolyte can be prevented from directly contacting the positive electrode current collector by the protective film. As a result, even if such a non-aqueous electrolyte battery is stored in a charged state, the non-aqueous electrolyte can be prevented from being decomposed, and the charge storage property is improved.

[0008] This is because a stable anion resulting from ionic dissociation of lithium perfluoroalkylsulfonimide or lithium perfluoroalkylsulfonate is bonded to carbon of the positive electrode current collector, so that the surface of the positive electrode current collector has good quality. (A film serving as a protective film) is formed. This is because the coating is stably present at a high temperature and blocks the contact between the positive electrode current collector and the solvent molecules of the non-aqueous electrolyte to prevent deterioration (decomposition) of the non-aqueous electrolyte.

Then, the spacing (d ₀₀₂ ) of the (002) plane
When a carbon material whose crystallite size in the c-axis direction (Lc) is 250 ° or more is used as a constituent material of the positive electrode current collector, the surface of the positive electrode current collector As a result, a dense and thin film is generated, so that deterioration (decomposition) of the nonaqueous electrolyte is further prevented.

The present invention can be used without any limitation on the positive electrode active material, the negative electrode active material, the solvent of the non-aqueous electrolyte, the type of separator, and the like. For example, as the positive electrode active material, the composition formula is Li _a MO _b (M is Co, N
one kind of metal element selected from i, Mn, Fe, etc.
A composite oxide of metal M and Li represented by 0 ≦ a ≦ 2 and 1 ≦ b ≦ 5) can be used. Specifically, modified M
nO ₂ , LiNiO ₂ , LiCoO ₂ , LiMn ₂ O ₄ , L
iMn _1.5 Ni _0.5 O ₄ is preferred.

Of these, the composition formula is LiMn _2-X Ni _X
When a composite oxide represented by O ₄ (0 <X ≦ 0.6) is used as the positive electrode active material, the positive electrode potential during charge storage increases, and a denser and higher quality coating is formed on the surface of the positive electrode current collector. And the charge storage characteristics are remarkably improved. Here, the reason why the composition of Ni in the composite oxide is limited to 0.6 or less is to suppress a decrease in the effect of improving the cycle life characteristics due to a structural change of the oxide phase of Ni.

As the negative electrode active material, graphite (natural graphite, artificial graphite) which can occlude and release Li electrochemically,
Carbon materials such as coke and fired organic material, Li-Al alloy, Li-Mg alloy, Li-In alloy, Li-Al-M
N-alloys and lithium metals are preferred.

As the solvent of the non-aqueous electrolyte, ethylene carbonate (EC), propylene carbonate (PC),
Cyclic carbonates such as butylene carbonate (BC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), diethyl carbonate (DE
A mixed solvent with a chain carbonate such as C) is preferred.
Further, the cyclic carbonate, 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DE
A mixed solvent with an ether solvent such as E) and ethoxymethoxyethane (EME) is also preferable.

Further, as the non-aqueous electrolyte, a gel polymer electrolyte obtained by impregnating a polymer such as polyethylene oxide or polyacrylonitrile with a non-aqueous electrolyte may be used. The non-aqueous electrolyte used in the present invention is a Li compound (LiN (C _m F
_{2m + 1} SO ₂ ) (C _n F _{2n + 1} SO ₂ ) (where m and n
Are each independently an integer from 1 to 4) represented by lithium perfluoroalkylsulfonic acid imide or LiC (C
_{p F 2p + 1 SO 2)} (C q F 2q + 1 SO 2) (C r F 2r + 1 SO 2)
(Where p, q and r are each independently an integer of 1 to 4), and a solvent for dissolving and maintaining the same is a voltage at the time of charging, discharging, or storing the battery. Can be used without restriction as long as it is not decomposed.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the nonaqueous electrolyte battery according to the present invention will be described below. 1. Preparation of positive electrode current collector Heat treatment was performed by heating the aromatic polyimide film (starting material) at a temperature of 2500 ° C. for 10 hours in an argon atmosphere to prepare a carbon sheet as a positive electrode current collector. When the obtained carbon sheet was analyzed, the (002) plane spacing (d _{00 2} ) was 3.358 °, and the crystallite size (Lc) in the c-axis direction was 600 °. As a starting material, a polymer film such as aromatic polyamide, polyphenylene oxadiazole, or polybenzothiazole may be used in addition to the aromatic polyimide film.

2. Preparation of positive electrode Lithium-containing cobalt oxide (Li
90 parts by weight of CoO ₂ ) powder, 5 parts by weight of a carbon-based conductive agent such as artificial graphite, acetylene black, and graphite, and 5 parts by weight of polyvinylidene fluoride (PVdF)
These were mixed with an N-methyl-2-pyrrolidone (NMP) solution to prepare a slurry. This slurry was uniformly applied to both surfaces of the carbon sheet (positive electrode current collector) prepared as described above using a doctor blade or the like to form a positive electrode plate coated with an active material layer. After this, 150 ° C
After drying under vacuum for 2 hours to remove the organic solvent necessary for preparing the slurry, the roll was rolled by a roll press to prepare a positive electrode plate 11 (see FIG. 1). As the positive electrode active material, modified MnO ₂ , L instead of LiCoO ₂
iNiO ₂ , LiCoO ₂ , LiMn ₂ O ₄ , LiMn _1.5
A composite oxide such as Ni _0.5 O ₄ may be used.

3. Preparation of negative electrode 95 parts by weight of natural graphite (d = 3.35 °) powder as a negative electrode active material and 5 parts of polyvinylidene fluoride (PVdF)
Parts by weight, and N-methyl-2-
A slurry was prepared by mixing with a pyrrolidone (NMP) solution. This slurry was uniformly applied to both surfaces of a copper negative electrode current collector having a thickness of 20 μm to form a negative electrode plate coated with an active material layer. Thereafter, drying was performed at a temperature of 150 ° C. to produce a negative electrode 12 made of a carbon material (see FIG. 1). Note that, as the carbon material, artificial graphite, coke, a fired organic material, or the like may be used instead of natural graphite.

4. Preparation of Electrolyte (Electrolyte) (1) Example 1 First, ethylene carbonate (EC: hereinafter simply referred to as EC) and diethyl carbonate (DEC: hereinafter simply D)
EC) is dissolved in a mixed solvent in a volume ratio of 50:50 by mixing 1.0 mol / L of LiN (CF ₃ SO ₂ ) ₂ as lithium perfluoroalkylsulfonimide to form an electrolytic solution (electrolyte). ) Was prepared. To this electrolyte solution, isoxazole was added as an additive in an amount of 5% by weight based on the electrolyte solution, and mixed to prepare an electrolyte solution a of Example 1. Note that LiN (CF ₃ S), which is a lithium perfluoroalkyl sulfonimide used as a solute, was used.
O ₂ ) ₂ is LiN (C _m F _{2m + 1} SO ₂ ) (C _n F _{2n + 1} S
O ₂ ) corresponds to m = 1 and n = 1. This is represented as (m, n) = (1, 1) below.

(2) Example 2 LiN (C ₂ F ₅ SO ₂ ) ₂ as lithium perfluoroalkylsulfonimide was added to a mixed solvent in which EC and DEC were mixed at a volume ratio of 50:50. 0 mol / liter was dissolved to prepare an electrolytic solution. To this electrolyte solution, isoxazole was added as an additive in an amount of 5% by weight based on the electrolyte solution and mixed to prepare an electrolyte solution b of Example 2. LiN (C ₂ F ₅ SO ₂ ) ₂ , which is a lithium perfluoroalkyl sulfonimide used as a solute,
_{LiN (C m F 2m + 1} SO 2) (C n F 2n + 1 SO 2) and represented when the (m, n) corresponding to = (2,2).

(3) Example 3 LiN (CF ₃ SO ₂ ) (C ₄ F ₉ S) as a lithium perfluoroalkyl sulfonimide was mixed in a mixed solvent of EC and DEC in a volume ratio of 50:50.
O ₂ ) was dissolved at 1.0 mol / liter to prepare an electrolyte solution. To this electrolyte solution, isoxazole was added as an additive in an amount of 5% by weight based on the electrolyte solution, and mixed to prepare an electrolyte solution c of Example 3. In addition, LiN which is lithium perfluoroalkylsulfonic acid imide used as a solute was used.
(CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ) is LiN (C _m F _{2m + 1)}
SO ₂ ) (C _n F _{2n + 1} SO ₂ ) when (m,
n) = (1, 4).

(4) Example 4 EC and DEC are mixed at a volume ratio of 50:50.
Lithium perfluoroalkyl sulfo
LiC (CF_ThreeSO_Two)_Three1.0 mol
/ Liter dissolved to prepare an electrolytic solution. Add this electrolyte
Isoxazole as additive is 5% by weight of the electrolyte
Then, the mixture was added and mixed to prepare an electrolyte solution d of Example 4. What
The lithium perfluoroalkyl used as the solute
Lisulfonate methide LiC (CF_ThreeSO_Two)_ThreeIs
LiC (C_pF_{2p + 1}SO_Two) (C_qF _{2q + 1}SO_Two) (C_rF
_{2r + 1}SO_Two), P = 1, q = 1, r =
1, ie, (p, q, r) = (1, 1, 1)
You.

(9) Comparative Example 1 In a mixed solvent in which EC and DEC were mixed at a volume ratio of 50:50, 1.0 mol / liter of lithium perfluoroalkylsulfonate (LiCF ₃ SO ₃ ) was dissolved. To prepare an electrolytic solution. To this electrolyte solution, isoxazole was added as an additive in an amount of 5% by weight based on the electrolyte solution, and mixed to prepare an electrolyte solution x of Comparative Example 1.

(10) Comparative Example 2 Lithium perfluoroalkylsulfonylamide (LiNHCF ₃ SO ₂ ) (1.0 mol / l) was dissolved in a mixed solvent of EC and DEC mixed at a volume ratio of 50:50. To prepare an electrolytic solution. Isoxazole as an additive was added to this electrolyte at a ratio of 5% by weight based on the electrolyte, and mixed to prepare an electrolyte y of Comparative Example 2.

In each of the above Examples and Comparative Examples, EC
And DEC are described as using a mixed solvent in which the volume ratio is 50:50. In addition to EC and DEC, propylene carbonate (PC) and butylene carbonate (BC) are used as the electrolyte solvent. And dimethyl carbonate (DM
C), a mixed solvent with a chain carbonate such as methyl ethyl carbonate (MEC), and the above cyclic carbonate;
1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), ethoxymethoxyethane (EM
A mixed solvent with an ether solvent such as E) may be selected and used.

[5] Production of Lithium Secondary Battery Next, an example of producing a lithium secondary battery will be described with reference to FIG. The positive electrode plate 11 and the negative electrode plate 12 produced as described above were overlapped with a separator 13 made of a microporous polypropylene film interposed therebetween, and then spirally wound to produce a spiral electrode body. . Next, a cylindrical outer can 14 is prepared, a spiral electrode body is inserted into the outer can 14, and a negative electrode lead 12 a extending from the negative electrode plate 12 is welded to the bottom of the outer can 14. The positive electrode lead 11a extending from the plate 11 is connected to the lid 1 of the sealing body.
6 was welded to the bottom.

Then, the electrolytes a to d of Examples 1 to 4 and the electrolytes x and x of Comparative Examples 1 and 2 prepared as described above were prepared.
After injecting the y into the outer can 14, the insulating packing 19 arranged on the periphery of the lid 16 is arranged on the concave portion 14a provided on the upper part of the outer can 14, and the opening provided on the upper part of the outer can 14 is formed. The portion 14b was liquid-tightly sealed by caulking inward to produce lithium secondary batteries 10 of AA size and A to D and XY of a nominal capacity of 600 mAh. In addition,
The sealing body is composed of a lid 16 and a positive electrode cap 15,
A projection 18 projecting downward from the positive electrode cap 15 is formed on the lower surface of the positive electrode cap 15, and a gas exhaust port (not shown) provided in the lid 16 is sealed on the upper surface of the lid 16. A valve element 17 is provided which swells upward due to an increase in battery internal pressure. A gas vent (not shown) is provided on the side wall of the positive electrode cap 15.

As a result, when the internal pressure of the battery rises above a predetermined pressure, the valve body 17 bulges upward and pierces the tip of the projection 18, so that the valve body 17 is damaged, and the battery is discharged from a gas exhaust port (not shown). Excess gas generated in the battery is discharged to the outside of the battery through the gas vent, and the battery 10
Can be prevented from exploding. Note that battery A
Is a battery in which the electrolyte a of Example 1 is injected, a battery B is a battery in which the electrolyte b of Example 2 is injected, and a battery C is a battery in which the electrolyte c of Example 3 is injected. D is obtained by injecting the electrolytic solution d of Example 4. The battery X was injected with the electrolyte x of Comparative Example 1, and the battery Y was injected with the electrolyte y of Comparative Example 2.

6. Charge / discharge cycle test Each of the batteries A to D and X, Y produced as described above was charged at a constant current of 4.2 mA at room temperature (25 ° C.) with a charge current of 200 mA until the voltage reached 4.2 V, and then discharged at 200 mA. In the flow 2.
Constant current discharge was performed until the voltage reached 75 V, and the initial discharge capacity was determined. Next, these batteries A to D and X, Y were
After charging at a constant current of 4.2 V with a charged current of 0 mA until storage at 60 ° C. for 20 days, discharging at a constant current of 2.75 V with a discharged current of 200 mA until the voltage reaches 2.75 V, and after high-temperature storage Was obtained. Next, when the ratio of the discharge capacity after high-temperature storage to the initial discharge capacity was calculated as the remaining capacity ratio, the results shown in Table 1 below were obtained.

[0029]

[Table 1]

As is clear from Table 1, the battery X of Comparative Example 1 in which lithium perfluoroalkylsulfonate (LiCF ₃ SO ₃ ) was used as the electrolyte salt, and lithium perfluoroalkylsulfonylamide (LiNHCF ₃ SO ₂ )
The remaining capacity of the battery Y of Comparative Example 2 in which
The remaining capacity of the batteries A to D of Examples 1 to 4 using lithium perfluoroalkylsulfonic acid imide or lithium perfluoroalkylsulfonic acid methide as the electrolyte salt was 72. 5%
７６76.7%, which indicates that the charge storage characteristics are excellent.

This is because the non-aqueous electrolyte contains lithium perfluoroalkylsulfonimide or lithium perfluoroalkylsulfonate methide, so that a good quality film due to stable anions can be formed on the surface of the carbon sheet (cathode current collector). It is presumed that this coating prevented contact between the carbon sheet (cathode current collector) and the solvent molecules to prevent deterioration of the non-aqueous electrolyte during charge storage.

7. Examination of the physical property value of the carbon sheet Next, the effect of the charge storage characteristic on the physical property value of the carbon sheet was examined. (1) Example 5 An aromatic polyimide film was coated with 180 in an argon atmosphere.
Heat treatment was performed at a temperature of 0 ° C. for 10 hours to produce a carbon sheet as a positive electrode current collector. When the obtained carbon sheet was analyzed, the spacing (d) of the (002) plane was determined.
₀₀₂ ) was 3.420 °, and the crystallite size (Lc) in the c-axis direction was 65 °. Using this positive electrode current collector, a positive electrode plate 11 was produced in the same manner as described above, and a spiral electrode body was produced using the negative electrode plate 12 produced in the same manner as above,
The lithium secondary battery 10 of Example 5 was manufactured using the electrolyte solution a of Example 1. This lithium secondary battery 10 is
And

(2) Example 6 An aromatic polyimide film was prepared for 200 hours in an argon atmosphere.
Heat treatment was performed at a temperature of 0 ° C. for 10 hours to produce a carbon sheet as a positive electrode current collector. When the obtained carbon sheet was analyzed, the spacing (d) of the (002) plane was determined.
₀₀₂ ) was 3.370 °, and the crystallite size (Lc) in the c-axis direction was 250 °. Using this positive electrode current collector, a positive electrode plate 11 was produced in the same manner as described above, and a spiral electrode body was produced using the negative electrode plate 12 produced in the same manner as described above, and the electrolyte solution a of Example 1 was used. Thus, a lithium secondary battery 10 of Example 6 was produced. This lithium secondary battery 10 was designated as Battery F.

(3) Example 7 An aromatic polyimide film was placed in an argon atmosphere at 230
Heat treatment was performed at a temperature of 0 ° C. for 10 hours to produce a carbon sheet as a positive electrode current collector. When the obtained carbon sheet was analyzed, the spacing (d) of the (002) plane was determined.
₀₀₂ ) was 3.365 ° and the crystallite size (Lc) in the c-axis direction was 480 °. Using this positive electrode current collector, a positive electrode plate 11 was produced in the same manner as described above, and a spiral electrode body was produced using the negative electrode plate 12 produced in the same manner as described above, and the electrolyte solution a of Example 1 was used. Thus, a lithium secondary battery 10 of Example 7 was produced. This lithium secondary battery 10 was referred to as battery G.

(4) Example 8 An aromatic polyimide film was coated with 280 in an argon atmosphere.
Heat treatment was performed at a temperature of 0 ° C. for 10 hours to produce a carbon sheet as a positive electrode current collector. When the obtained carbon sheet was analyzed, the spacing (d) of the (002) plane was determined.
₀₀₂ ) was 3.354 ° and the crystallite size (Lc) in the c-axis direction was 850 °. Using this positive electrode current collector, a positive electrode plate 11 was produced in the same manner as described above, and a spiral electrode body was produced using the negative electrode plate 12 produced in the same manner as described above, and the electrolyte solution a of Example 1 was used. Thus, a lithium secondary battery 10 of Example 8 was produced. This lithium secondary battery 10 was designated as Battery H.

(5) Example 9 An aromatic polyimide film was prepared in an argon atmosphere at 300
Heat treatment was performed at a temperature of 0 ° C. for 10 hours to produce a carbon sheet as a positive electrode current collector. When the obtained carbon sheet was analyzed, the spacing (d) of the (002) plane was determined.
₀₀₂ ) was 3.354 ° and the crystallite size (Lc) in the c-axis direction was 1200 °. Using this positive electrode current collector, a positive electrode plate 11 was produced in the same manner as described above, and a spiral electrode body was produced using the negative electrode plate 12 produced in the same manner as described above, and the electrolyte solution a of Example 1 was used. Thus, a lithium secondary battery 10 of Example 9 was produced. This lithium secondary battery 10 was referred to as Battery I.

Next, each of the batteries E to E produced as described above was used.
3. I was charged at room temperature (25 ° C.) with a charge current of 200 mA.
After constant-current charging until the voltage reached 2 V, constant-current discharging was performed at a discharge current of 200 mA until the voltage reached 2.75 V, and the initial discharge capacity was determined. Next, each of these batteries E to I was 200 m
After charging at a constant current until the voltage of A reaches 4.2 V,
After being stored at a temperature of 60 ° C. for 20 days, the battery was discharged at a constant current of 200 mA at a discharge current of 2.75 V until the discharge capacity after storage at a high temperature was determined. Next, when the ratio of the discharge capacity after high-temperature storage to the initial discharge capacity was calculated as the remaining capacity ratio, the results shown in Table 2 below were obtained. Table 2 also shows the results of the battery A of Example 1.

[0038]

[Table 2]

As is clear from Table 2, (002)
The plane spacing (d ₀₀₂ ) of the planes is greater than 3.37 ° and c
The remaining capacity of the battery E of Example 5 in which the crystallite size (Lc) in the axial direction was less than 250 ° showed a low value of 58.4%. On the other hand, in Examples 1 and 2, the spacing (d ₀₀₂ ) of the (002) plane was 3.35 ° or more and 3.37 ° or less, and the crystallite size (Lc) in the c-axis direction was 250 ° or more. The remaining capacity of the batteries A and FI of Examples 6 to 9 was 7
It is 1.3% to 81.0%, which indicates that the battery has excellent charge storage characteristics.

This is the distance (d ₀₀₂ ) between the (002) planes.
The carbon sheet whose is not less than 3.35 ° and not more than 3.37 ° and the crystallite size (Lc) in the c-axis direction is not less than 250 ° has lithium perfluoroalkylsulfonic acid imide or lithium perfluoroalkylsulfonic acid methide on its surface. It is considered that a denser and thinner film was formed at the time of film formation caused by stable anions due to the above. From this, it is necessary to use a carbon sheet in which the (002) plane spacing (d ₀₀₂ ) is 3.35 ° or more and 3.37 ° or less and the crystallite size (Lc) in the c-axis direction is 250 ° or more. Can be preferred.

8. Investigation of positive electrode active material Next, the effect of the positive electrode active material on the charge storage characteristics was examined. (1) Example 10 After mixing LiOH, MnO ₂ and Ni (OH) ₂ in a mortar such that the molar ratio of each element is Li: Mn: Ni = 1: 1.5: 0.5. A heat treatment was performed at a temperature of 750 ° C. for 20 hours in an oxygen atmosphere. Next, this was pulverized to obtain a composite oxide represented by LiMn _1.5 Ni _0.5 O ₄ . Using this composite oxide as a positive electrode active material, a positive electrode plate 11 was produced in the same manner as described above using the carbon sheet (positive electrode current collector) of Example 1, and a negative electrode plate 12 produced in the same manner as described above The spirally wound electrode body is manufactured by using the lithium secondary battery 1 of Example 10 using the electrolyte solution a of Example 1.
0 was produced. This lithium secondary battery 10 was designated as Battery J.

Next, the battery J prepared as described above was charged at room temperature (25 ° C.) with a constant current of 200 mA until the voltage reached 4.2 V, and then charged at 2.75 V with a discharge current of 200 mA. The discharge was carried out at a constant current until the discharge capacity reached, and the initial discharge capacity was determined. Subsequently, the battery J was charged at a constant current of 200 mA at a charge current of 4.2 V until it reached 4.2 V, stored at a temperature of 60 ° C. for 20 days, and then charged at a current of 200 mA with a discharge current of 2.75.
The battery was discharged at a constant current until the voltage reached V, and the discharge capacity after high temperature storage was determined. Next, when the ratio of the discharge capacity after high-temperature storage to the initial discharge capacity was calculated as the remaining capacity ratio, the results shown in Table 3 below were obtained. Table 3 also shows the results of the battery A of Example 1.

[0043]

[Table 3]

As is clear from Table 3, the capacity remaining ratio of the battery J using LiMn _1.5 Ni _0.5 O ₄ (0 <X ≦ 0.6) as the positive electrode active material was LiCo as the positive electrode active material.
It can be understood that the capacity remaining ratio of the battery A using O ₂ is improved and the battery A has excellent charge storage characteristics. This is because when a composite oxide represented by a composition formula of LiMn _2-X Ni _X O ₄ is used as a positive electrode active material, the positive electrode potential during charge storage increases, and a denser and higher quality coating is formed on a carbon sheet ( This is because it was formed on the surface of the positive electrode current collector, and the effect of improving the charge storage characteristics was remarkably obtained. Here, N in the composite oxide
The reason why the composition X of i is defined to be 0.6 or less is to suppress a decrease in the cycle life characteristic improving effect due to a structural change of the Ni oxide phase.

As described in detail above, in the present invention, the specific electrolyte salt (LiN (C _m F _{2 m + 1} SO ₂ ) (C _n
F _{2n + 1} SO ₂ ) (where m and n are each independent 1)
To 4 lithium perfluoroalkylsulfonic acid imide or LiC represented by an _{integer) (C p F 2p + 1} SO 2)
_{(C q F 2q + 1 SO} 2) (C r F 2r + 1 SO 2) ( however, p,
q and r each represent an independent integer of 1 to 4)) and a specific positive electrode current collector (surface spacing (d
₀₀₂ ) is 3.35 ° or more and 3.37 ° or less and carbon having a crystallite size (Lc) of 250 ° or more in the c-axis direction is used, which results from the decomposition of the solvent of the non-aqueous electrolyte. Deterioration of the non-aqueous electrolyte is suppressed, and a non-aqueous electrolyte battery having excellent charge storage characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross section of a lithium secondary battery according to one embodiment of the present invention.

[Explanation of symbols]

10: lithium secondary battery, 11: positive electrode, 12: negative electrode, 1
3 ... separator, 14 ... outer can, 15 ... positive electrode cap,
16 ... lid, 17 valve, 18 ... projection, 19 ... insulating packing

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shin Fujitani 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in SANYO Electric Co., Ltd. 4G048 AA04 AC06 AD06 AE05 5H003 AA03 BB05 BB12 BD00 BD03 5H014 AA04 EE07 EE10 HH01 5H017 AA03 AS02 EE06 HH01 5H029 AJ04 AJ07 AK03 AL06 AL07 AL12 AM01 AM02 AM03 AM04 AM05 AM07 BJ02 BJ14 DJ07 EJ04 HJ02 HJ13

Claims (4)

[Claims] 1. A non-aqueous electrolyte battery comprising: a positive electrode having a positive electrode current collector coated with a positive electrode active material capable of inserting and removing lithium ions; and a negative electrode capable of inserting and removing lithium ions. And a carbon material as a constituent material of the positive electrode current collector, and LiN (C _m F _{2m + 1} SO ₂ ) (C _n F _{2n + 1} SO ₂ ) (where m and n are each 1 to 4 lithium perfluoroalkylsulfonic acid imide or LiC represented by an _{integer) (C p F 2p + 1} SO 2) (C q F 2q + 1 SO 2) (C
_r F _{2r + 1} SO ₂ ) (where p, q and r are each independently an integer of 1 to 4), containing at least one electrolyte salt selected from lithium perfluoroalkylsulfonic acid methide. A non-aqueous electrolyte battery comprising a water electrolyte. 2. The carbon material has a (002) plane spacing (d ₀₀₂ ) of not less than 3.35 ° and not more than 3.37 °, and a crystallite size (Lc) in the c-axis direction of not less than 250 °. The non-aqueous electrolyte battery according to claim 1, wherein: 3. The positive electrode active material has a composition formula of Li _a MO
_b (where M is at least one metal element selected from Co, Ni, Mn, Fe, 0 ≦ a ≦ 2; 1 ≦ b
The non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte battery is a lithium-containing metal oxide represented by ≦ 5). 4. The positive electrode active material has a composition formula of LiMn _2-X
Ni _X O ₄ (where, 0 <X ≦ 0.6) a non-aqueous electrolyte battery according to any one of claims 1 to claim 3, characterized in that a lithium-containing composite metal oxide represented by.