JP3016447B2 - Non-aqueous electrolyte battery - Google Patents

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, and more particularly to a solute of the non-aqueous electrolyte.

[0002]

2. Description of the Related Art In recent years, lithium or a lithium alloy or a carbon material has been used as a negative electrode active material, and manganese dioxide (MnO ₂ ), molybdenum disulfide (MoS ₂ ), lithium cobalt composite oxide has been used as a positive electrode active material. (Li
CoO ₂ ) or the like, and propylene carbonate (PC), 1,2-dimethoxyethane (DME), γ-
Butyrolactone (γ-BL), tetrahydrofuran (T
HF) or other non-aqueous solvent containing LiClO ₄ , LiBF ₄ ,
A battery using an electrolytic solution in which a lithium salt such as LiAsF ₆ , LiPF ₆ , or LiCF ₃ SO ₃ is dissolved is known.
The combination of the negative electrode, the positive electrode, and the electrolytic solution provides a high-capacity, high-energy density battery.

[0003]

However, LiCl
O ₄ , LiBF ₄ , LiAsF ₆ , LiPF ₆ , LiC
A battery using an electrolytic solution in which F ₃ SO ₃ or the like is dissolved has a problem that self-discharge is large. On the other hand, in recent years, LiN (C
A battery using an electrolytic solution in which F ₃ SO ₂ ) ₂ or LiC (CF ₃ SO ₂ ) ₃ or the like is dissolved has been studied. However, these have low self-discharge, but large anions,
The conductivity as an electrolyte tends to be lower than when other solutes are used.

The present invention has been made in order to solve the above-mentioned problems, and includes LiAsF ₆ , LiClO ₄ ,
Electrolyte using a mixture of at least one lithium salt selected from the group consisting of LiBF ₄ , LiPF ₆ and LiCF ₃ SO ₃ and at least two or more lithium salts containing at least one lithium salt represented by the following formula The purpose of the present invention is to provide a non-aqueous electrolyte battery having improved electrolyte conductivity and improved storage characteristics. _{LiN (C n X 2n + 1} Y) 2 ............... LiC (C n X 2n + 1 Y) 3 ............... LiCR (C n X 2n + 1 Y) 2 ............... However, X: F, Cl, Br, I Y: CO, SO ₂ n: an integer from 1 to 4 R: an alkyl group

[0005]

According to the present invention, there is provided a negative electrode comprising lithium or an alloy thereof or a composite of lithium and a carbon material, a positive electrode, and an electrolyte comprising a solute and a solvent, wherein the solute is LiAsF ₆ , LiClO 2. _4, LiBF _4, Li
A mixture of at least one kind of lithium salt selected from the group consisting of PF ₆ and LiCF ₃ SO ₃ and at least two kinds of lithium salts containing at least one kind of lithium salt having the structure of the above formula (1) or (2) is used. It is a non-aqueous electrolyte battery. As the lithium salt having the above structure, L
iN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ ,
LiCCH ₃ (CF ₃ SO ₂ ) _{2 and the} like, but are not particularly limited thereto. According to the above configuration, a non-aqueous electrolyte battery having a high energy density, in which the conductivity of the electrolyte is improved, the storage characteristics are improved, and the self-discharge is reduced.

[0006]

Embodiment 1 The present invention will be described below with reference to embodiments. (Example 1) FIG. 1 is a sectional view of a lithium secondary battery using manganese dioxide for a positive electrode, metallic lithium for a negative electrode, and a non-aqueous electrolyte. Reference numeral 1 denotes a case also serving as a positive electrode terminal, 2 denotes a sealing plate serving as a negative electrode terminal, and 3 denotes a polypropylene gasket for insulating the case and the sealing plate. Reference numeral 4 denotes a positive electrode, which is composed of 85 parts by weight of manganese dioxide, acetylene black 1
0 parts by weight and 5 parts by weight of polytetrafluoroethylene were kneaded and formed into a sheet having a thickness of 0.7 mm.
It is formed by punching to 0 mm. After that, it was dried at high temperature under vacuum and pressure-bonded to the positive electrode current collector 5 which had been welded to the case 1 in advance. Reference numeral 6 denotes a negative electrode formed of lithium metal,
It was pressed to the negative electrode current collector 7 with a thickness of 0.4 mm and a diameter of 16 mm. Reference numeral 8 denotes a separator made of a polypropylene microporous membrane. As the electrolyte, propylene carbonate (PC) and 1,2-dimethoxyethane (DME) were used as solvents.
And a mixing ratio of 1: 1 was used. LiBF ₄ and LiN (CF ₃ SO ₂ ) ₂ were used as solutes in an amount of 0.
The solution dissolved at 5 mol / l was used. The battery created with the above configuration is referred to as battery A.

(Example 2) LiBF as a solute of an electrolytic solution
₄ and LiC (CF ₃ SO ₂ ) ₃ each in 0.5 mol
Everything was prepared in the same manner as in Example 1 except that the solution dissolved in / l was used. This battery is referred to as battery B.

(Comparative Example 1) LiBF as a solute of an electrolytic solution
All were prepared in the same manner as in Example 1 except that ₄ was dissolved at 1 mol / l. This battery is referred to as battery C.

Comparative Example 2 LiN was used as a solute of the electrolytic solution.
Except for using 1 mol / l of (CF ₃ SO ₂ ) ₂ dissolved, all were prepared in the same manner as in Example 1. This battery is referred to as Battery D.

Comparative Example 3 LiC as a solute of an electrolytic solution
(CF ₃ SO ₂ ) ₃ was prepared in the same manner as in Example 1 except that 1 mol / l was used. This battery is referred to as battery E.

The batteries A, B, C,
The following tests were performed for D and E. The test conditions are as follows. (Capacity test) Test temperature: 25 ° C Charge: constant current 0.5 mA, end voltage 3.5 V Discharge: constant current 1.0 mA, end voltage 2.4 V

(Storage test) Test temperature: 25 ° C. Charge: constant current 0.5 mA, final voltage 3.5 V Storage: After 10 cycles of charge, left at 60 ° C. for 20 days Discharge: constant current 1.0 mA, final voltage 2. 4V

Table 1 shows Examples 1 and 2 and Comparative Example 1.
The conductivity at 20 ° C. of the electrolyte solution used in 2 and 3 is shown. Table 1
As is clear, the electrolytes used in Examples 1 and 2 have higher conductivity than the electrolytes used in Comparative Examples 2 and 3, and the effect of the present invention is exhibited. .

[0014]

Table 2 shows the results of one cycle of the discharge capacity in the capacity test. However, the initial capacity of battery A is 100%
And As is clear from Table 2, batteries A and B correspond to battery D,
It can be seen that the capacity is larger than that of E and the effect of the present invention is exhibited.

[0016]

Table 3 shows the results of the storage test. As is clear from Table 3, the amount of self-discharge due to storage of the batteries A and B is smaller than that of the battery C, and the effect of the present invention that the self-discharge is suppressed is exhibited. From the above results, the batteries A and B had almost the same amount of self-discharge as the batteries D and E, but the conductivity and capacity of the electrolyte solution were improved. The batteries A and B have almost the same conductivity and capacity of the electrolytic solution as the battery C, but have improved self-discharge. Although the cause of these improvements is not clear, due to the common ionic effect due to the addition of the salt used in the present invention,
It is considered that the dissociation of LiBF ₄ was reduced and self-discharge was reduced.

[0018]

Although the solvent according to the present invention is not particularly limited, for example, a solvent having a high dielectric constant represented by propylene carbonate, ethylene carbonate, γ-butyrolactone, sulfolane, etc., and tetrahydrofuran,
There is a low-viscosity solvent represented by -methyltetrahydrofuran, 1,2-dimethoxyethane, and 1,3-dioxolane. Among these, an electrolytic solution using one or more solvents is preferable.

[0020]

As described above, the present invention suppresses self-discharge, improves storage characteristics, improves the conductivity of the electrolyte,
Since a non-aqueous electrolyte battery having a higher energy density can be provided, its industrial value is extremely large.

[Brief description of the drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Case 2 Sealing plate 3 Gasket 4 Positive electrode 5 Positive electrode collector 6 Negative electrode 7 Negative electrode collector 8 Separator

Claims (1)

(57) [Claims] A negative electrode comprising lithium or an alloy thereof or a composite of lithium and a carbon material, a positive electrode, and an electrolytic solution comprising a solute and a solvent, wherein the solute is LiAsF ₆ , LiC
10 ₄ , LiBF ₄ , LiPF ₆ and LiCF ₃ SO ₃
A non-aqueous electrolyte battery using a mixture of at least one lithium salt selected from the group consisting of and at least two or more lithium salts containing at least one lithium salt represented by the following formula. _{LiN (C n X 2n + 1} Y) 2 ............... LiC (C n X 2n + 1 Y) 3 ............... LiCR (C n X 2n + 1 Y) 2 ............... However, X: F, Cl, Br, I Y: CO, SO ₂ n: an integer from 1 to 4 R: an alkyl group