JPS60193272A - Nonaqueous electrolyte battery - Google Patents

Abstract

PURPOSE:To obtain a nonaqueous electrolyte battery having good high rate discharge performance by using mixed solvent containing at least methyl sulfoxide and fatty ester as solvent. CONSTITUTION:A mixed solvent having a mixing ratio of 1:1 of dimethyl sulfoxide and methyl acetate is used as solvent. Electrolyte is prepared by dissolving lithium perchlorate serving as solute in this mixed solvent. Carbon powder and fluorine resin powder is mixed to manganese dioxide, and the mixture is press-molded, then heated to use as a positive electrode. Lithium plate is punched in a specified dimension to use as a negative electrode. Since solvent is prepared by mixing dimethyl sulfoxide having high dielectric constant and high viscosity and methyl acetate having low dielectric constant and low viscosity, disadvantage of single solvent is suppressed by synergetic effect of both solvents and electrolyte having high conductivity is obtained. This results in good high rate discharge performance.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to a negative electrode using light metals such as lithium, sodium, or alloys thereof as an active material, and a negative electrode using a metal oxide, sulfide, halide, etc. as an active material. The present invention relates to a non-aqueous electrolyte battery comprising a positive electrode and a non-aqueous electrolyte comprising a solute and a solvent, and particularly relates to improvements in the non-aqueous electrolyte.

(b) Prior Art Various solutes and solvents have been proposed for forming the non-aqueous electrolyte used in this type of battery.

Solutes include lithium perchlorate, lithium fluoroborate,
Lithium trifluoromethanesulfonate and the like are used, and examples of solvents include r-butyrolactone, propylene carbonate, dimethyl sulfoxide, 3-methyl-2-
Oxazolidone, tetrahydrofuron, etc. are used.

Now, in recent years, as the fields of application of this type of battery have expanded, there has been a demand for improvements in battery characteristics, and one of these is the desire to improve high rate discharge characteristics.

Incidentally, from the viewpoint of conductivity and ion diffusion, a solvent suitable for high rate discharge is required to have a high dielectric constant and a low viscosity, but in general, a solvent with a high dielectric constant has a high viscosity;
Solvents with low viscosity have low dielectric constants.

Therefore, by mixing a high viscosity solvent and a low viscosity solvent, it is possible to obtain a solvent having a high dielectric constant and low viscosity. However, combinations of various solvents have not yet been sufficiently studied.

(c) Purpose of the Invention The object of the present invention is to provide a non-aqueous electrolyte battery that improves the non-aqueous electrolyte and has excellent high-rate discharge characteristics in °C.

(d) Structure of the Invention The present invention provides a non-aqueous electrolyte battery comprising a negative electrode using light metals such as lithium and sodium or alloys thereof as active materials, a positive electrode, and a non-aqueous electrolyte comprising a solute and a solvent. The method is characterized in that a mixed solvent containing at least dimethyl sulfoxide and fatty acid ester is used as the solvent.

(e) Examples Examples of the present invention will be described in detail below.

A mixed solvent in which dimethyl sulfoxide and methyl acetate are mixed at a mixing ratio of 1:1 is used as a solvent, and an electrolyte solution is prepared by dissolving 1 mole of lithium perchlorate as a solute in this mixed solvent.

The positive electrode uses manganese dioxide heat-treated at 350 to 430°C as an active material, and this manganese dioxide is mixed with carbon powder (conductive agent) and fluororesin powder (binding agent) at a ratio of 85:10.
After mixing at a weight ratio of :5, this mixture was pressure molded and heat treated at 250 to 350°C.

The negative electrode was a lithium rolled plate punched out to the specified dimensions, with a diameter of 20.0 mm, a thickness of 2.5 mm, and a battery capacity of 1.
A 20 mAH battery (A) of the present invention was prepared.

Next, in order to examine the superiority of the battery of the present invention, a comparative battery (B) using dimethyl sulfoxide alone as a solvent,
Similarly, a comparative battery (C) using methyl acetate alone was prepared. Note that the comparative batteries (B) and (C) are the same as the batteries of the present invention except for the solvent.

FIG. 1 is a comparison diagram of discharge characteristics when these batteries were discharged at a constant resistance of 500Ω at 25°C.

Moreover, FIG. 2 is a diagram showing the relationship between the mixing ratio of the mixed solvent and the electrical conductivity of the electrolytic solution in the present invention.
It can be seen that high conductivity is exhibited in the range of 50,150, and in particular, the highest conductivity is exhibited in the case of a mixing ratio of 50150.

(f) Effects of the Invention As is clear from FIG. 1, the battery of the present invention exhibits superior high rate discharge characteristics compared to the comparative battery.

Considering the reason for this, in the battery of the present invention, the solvent constituting the nonaqueous electrolyte is composed of a mixed solvent of dimethyl sulfoxide, which has a high dielectric constant and high viscosity, and methyl acetate, which has a low dielectric constant and low viscosity. It is thought that due to the mutual action of the two, the drawbacks of a single solvent are suppressed and an electrolyte with high conductivity is formed, resulting in excellent high rate discharge characteristics.

Although methyl acetate was shown in the example as an example of a fatty acid ester that is a low dielectric constant and low viscosity solvent, similar effects can be obtained by using ethyl formate or ethyl acetate.

As mentioned above, by using a mixed solvent of dimethyl sulfoxide and fatty acid ester as a solvent, the high rate discharge characteristics of non-aqueous electrolyte batteries can be improved, which greatly contributes to expanding the applications of this type of battery. .

[Brief explanation of the drawing]

FIG. 1 is a comparison diagram of the high rate discharge characteristics of a battery of the present invention and a comparative battery, and FIG. 2 is a diagram showing the relationship between the mixing ratio of the mixed solvent and the conductivity of the electrolytic solution. (A)...Battery of the present invention, (B)<C)...Comparison battery. Applicant Sanyo Oki Co., Ltd. Agent Patent Attorney Shizuo Sano

Claims (1)

[Claims] (1) Comprising a negative electrode whose active material is a light metal such as lithium or sodium or an alloy thereof, a positive electrode, and a non-aqueous electrolyte comprising a solute and a solvent, where the solvent contains at least dimethyl sulfoxide and a fatty acid ester. A non-aqueous electrolyte battery characterized by a mixed solvent.