JPH0630258B2 - Organic electrolyte battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to an organic electrolyte battery. For more details,
General formula (I) LiXFn (I) (In formula, X is P, As, Sb or B, and n is X, P,
The present invention relates to an organic electrolyte battery in which the thermal stability of an organic electrolyte solution using a Lewis acid salt represented by the formula (6) in the case of As or Sb and 4 in the case of X is B is improved, and the storage characteristics are improved.

[Conventional technology]

Recently, a Lewis acid salt represented by the general formula (I) as a solute of an electrolyte solution of an organic electrolyte battery (hereinafter referred to as an electrolyte solution) has good solubility in an organic solvent, high conductivity, and perchloric acid. It is attracting attention because it has higher stability than that of the system, and various proposals have been made in the past regarding this. For example, in US Pat. No. 3,607,020 L
iPF _6, is proposed LiAsF ₆ synthesis, such as, in U.S. Pat. No. 3,907,977 using a _CH 3 CN Li
A method for synthesizing and purifying high-purity products of PF ₆ and LiAsF ₆ has been proposed. In US Pat. No. 3,639,174, LiPF ₆ / propylene carbonate and LiPF _{6 are} used as electrolytes in a Li--Al negative electrode / Cu ₂ S battery system.
A battery system using ₆ / dimethyl sulfoxide or the like has been proposed.

[Problems to be solved by the invention]

However, according to the experiments by the present inventors, LiPF ₆ was added to propylene carbonate, 1,3-dioxolane, tetrahydrofuran, 4-methyl-1,3-dioxolane,
A lithium organic electrolyte battery using an electrolytic solution dissolved in an organic solvent such as 1,2-dimethoxyethane shows good battery characteristics at room temperature, but when stored at 60 ° C, LiPF ₆ which is a solute is thermally decomposed. As a result, HF (hydrogen fluoride) is generated, and this HF causes decomposition or polymerization of the electrolytic solution solvent, resulting in a marked decrease in battery characteristics.
Further, like LiPF _6, Li represented by the general formula (I) is used.
Similar to LiPF ₆ , Lewis acid salts such as SbF ₆ , LiAsF ₆ and LiBF ₄ also have a problem in terms of thermal stability, and when they are stored at a high temperature, they are thermally decomposed to cause decomposition or polymerization of the electrolyte solvent. There is a problem of degrading battery characteristics.

[Means for solving problems]

This invention solves the above-mentioned problems of the prior art. The thermal stability of the electrolytic solution is improved by adding spartein to the electrolytic solution containing the Lewis acid salt represented by the general formula (I) as a solute. The present invention provides an organic electrolyte battery in which the deterioration of the battery performance during storage is reduced by increasing the temperature.

In the present invention, sparteine added to the electrolytic solution to increase the thermal stability of the electrolytic solution is an oily liquid present in Enishida also called lupinidine, having the following structural formula, Two tertiary amines form a stable complex with the Li ⁺ ion of the Lewis acid salt represented by the general formula (I), which is ionized in the electrolytic solution to stabilize the electrolytic solution.

Since the sparteine is a tetracyclic tertiary diamine and is a large molecule, it is difficult for the sparteine to enter the interlayer of titanium disulfide (TiS ₂ ) which is favorably used as a positive electrode active material in forming a secondary battery, and LiPF ₆ Since it has a basicity that can neutralize the HF generated by decomposition of the above, the electrolytic solution can be stabilized even with a small amount of use.

This sparteine has a larger effect of stabilizing the electrolytic solution as it increases, and from this aspect, the larger the amount added, the more preferable it is, but if it is too large, the conductivity at low temperature and the charging / discharging when used in a secondary battery are increased. Since the characteristics are deteriorated, the addition amount thereof is preferably 0.2 to 2 times mol of the Lewis acid salt represented by the general formula (I).

In the present invention, specific examples of the Lewis acid salt represented by the general formula (I) used as the solute of the electrolytic solution include LiPF ₆ (lithium hexafluorophosphate) in which X is P (phosphorus), X
Is Sb (antimony), LiSbF ₆ (lithium hexafluoroantimonate), and X is As (arsenic), LiA
sF ₆ (lithium hexafluoroarsenate), X is B (boron)
Is LiBF ₄ (lithium tetrafluoroborate).
Then, the electrolytic solution contains the Lewis acid salt represented by the general formula (I) such as propylene carbonate, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahitofuran, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,3-dioxolane, 4-methyl-1,3
-Dissolving in an organic solvent such as dioxolane or a mixed solvent of two or more kinds, and adding sparteine thereto,
Alternatively, it is prepared by adding sparteine to an organic solvent and then dissolving the Lewis acid salt represented by the general formula (I) therein. What is essential is that the electrolyte solution contains the Lewis acid salt represented by the general formula (I) and sparteine, and the order of addition of the sparteine and the Lewis acid salt represented by the general formula (I) does not matter. . The amount of the Lewis acid salt represented by the general formula (I) in the electrolytic solution is usually 0.1 to 3 mol.
l / dm ³ .

In the battery of the present invention, as the negative electrode active material, for example, lithium alloys such as lithium, lithium-aluminum, lithium-lead, lithium-indium, lithium-gallium-indium, lithium-magnesium, lithium-zinc are used, and the positive electrode active material is used. Examples of the substance include titanium disulfide (TiS ₂ ), molybdenum disulfide (MoS)
₂ ), molybdenum trisulfide (MoS ₃ ), zirconium sulfide (ZrS ₂ ), niobium disulfide (NbS ₂ ), phosphorous nickel trisulfide (NiPS ₃ ), vanadium selenide (V
Se ₂ ), iron sulfide, copper oxide, fluorocarbon, etc. are used. In particular, when used as a secondary battery, titanium disulfide is preferably used because it has a layered structure and has a large lithium diffusion constant.

〔Example〕

Next, the present invention will be described in more detail with reference to examples.

Example 1 mol of LiPF ₆ was added to a mixed solvent consisting of 57.5% by volume of 4-methyl-1,3-dioxolane, 38% by volume of 1,2-dimethoxyethane and 4.5% by volume of sparteine as an electrolytic solution.
A lithium-aluminum alloy containing 40 atomic% of lithium is used for the negative electrode, using an organic electrolyte solution dissolved so that the concentration of the electrolyte becomes / dm ³ .
A lithium organic electrolyte battery shown in FIG. 3 was assembled using a molding mixture containing titanium disulfide as a positive electrode active material for the positive electrode. In the electrolyte solution, sparteine corresponds to about 0.3 times mol of LiPF ₆ .

In FIG. 3, reference numeral 1 is a negative electrode can, the negative electrode can 1 is made of stainless steel and the surface thereof is nickel plated, and 2 is a negative electrode side current collecting net made of stainless steel, which is spotted on the inner surface of the negative electrode can 1. It is welded. Reference numeral 3 is a negative electrode made of a lithium-aluminum alloy, and 4 is a separator made of a microporous polypropylene film. Reference numeral 5 is an electrolyte absorber made of polypropylene nonwoven fabric, 6 is a positive electrode formed by pressure molding in the form of a mixture pellet containing titanium disulfide as a positive electrode active material, and 7 is a positive electrode side current collecting net made of stainless steel. . Reference numeral 8 is a positive electrode can made of stainless steel and having a surface plated with nickel, and 9 is an annular gasket made of polypropylene. The theoretical electricity quantity of the negative electrode of this battery is about 30 mAh, and the theoretical electricity quantity of the positive electrode is 13 mAh.

Comparative Example An organic electrolyte solution prepared by dissolving LiPF _{6 in an amount} of 1 mol / dm ^{3 in a} mixed solvent consisting of 60% by volume of 4-methyl-1,3-dioxolane and 40% by volume of 1,2-dimethoxyethane was used as an electrolytic solution. A lithium organic electrolyte battery similar to that of the example was assembled except that it was used.

The batteries of the above Examples and Comparative Examples were stored at 60 ° C.,
The change in internal resistance with storage at 10 kHz and the change in closed circuit voltage after discharge of 300 Ω for 5 seconds were examined. The change in internal resistance at 10 kHz is shown in FIG. 1, and the change in closed circuit voltage is shown in FIG. 10 kHz
The internal resistance of is a resistance almost dependent on the electrolytic solution.

As shown in FIG. 1, in the battery of the comparative example which is a conventional battery, the internal resistance increased remarkably with the increase in the number of days of storage, but in the battery of the example of the present invention, such a large internal resistance No increase was observed.

Further, as shown in FIG. 2, the battery of the embodiment of the present invention is
Compared to the battery of Comparative Example, the decrease in the closed circuit voltage due to storage was small, and the storage characteristics were excellent.

In the embodiment, as a Lewis acid salt represented by the general formula (I), although the case of using LiPF _6, the present invention is applied to a case of using such LiAsF _6, LiSbF _6, LiBF ₄ Needless to say.

〔The invention's effect〕

As described above, in the present invention, by adding sparteine as a stabilizer, the thermal stability of the electrolytic solution was enhanced, and an organic electrolyte battery having good storage characteristics could be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a change in internal resistance of a battery of an example of the present invention and a battery of a comparative example during storage at 10 kHz, and FIG. It is a figure which shows the closed circuit voltage change accompanying. FIG. 3 is a sectional view showing an example of the organic electrolyte battery according to the present invention. 3 ... Negative electrode, 4 ... Separator, 6 ... Positive electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-59-108276 (JP, A) JP-A-55-46298 (JP, A) JP-A-59-68184 (JP, A) JP-B-51- 3890 (JP, B2)

Claims (3)

[Claims] 1. A negative electrode containing lithium and a positive electrode, wherein the solute has the general formula (I) LiXFn (I) (wherein X is P, As, Sb or B, and n is X, P or As. Or 6 when Sb and 4 when X is B), wherein the solvent is an organic solvent, and an organic electrolyte solution to which sparteine is added as a stabilizer is used. And an organic electrolyte battery. 2. The organic electrolyte battery according to claim 1, wherein the Lewis acid salt is LiPF ₆ . 3. The organic electrolyte battery according to claim 1, wherein the positive electrode active material is titanium disulfide.