JPS6116479A - Nonaqueous electrolyte battery - Google Patents

Abstract

PURPOSE:To improve the high rate discharge characteristics by constructing a battery from a negative electrode having a light metal such as Li or Na or its alloy as the active material, a positive electrode, nonaqueous electrolyte composed of a solute and solvent, and by forming the solvent from the specified components. CONSTITUTION:When a mixed solvent which contains at least propylene carbonate and triether is used as the solvent of the nonaqueous electrolyte, the solute dissociates more readily than when a single solvent or other mixed solvents are used. Furthermore, as the energy required for migration of the solute is decreased, the reaction of the ions of the negative electrode active material with those of the positive electrode active material is carried out smoothly. For example, the batteries A1, A2 which contain propylene carbonate and diethylene glycol dimethyl ether mixed in 1:1 proportion, and propylene carbonate and diethylene glycol ether mixed in 1:1 proportion respectively show improved high rate discharge characteristics compared to a battery B containing propylene carbonate alone, or a battery C containing diethylene glycol dimethyl ether alone, or a battery D containing propylene carbonate and 1,2-dimethoxy ethane mixed in 1:1 proportion.

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 solvent and a solute, and particularly relates to improvements in the non-aqueous electrolyte.

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

Specifically, as disclosed in Japanese Patent Publication No. 57-32866, propylene carbonate, r-butyrolactone, dimethoxyethane, dioquinrane, tetrahydrofuran, etc. are used as solvents, and lithium perchlorate, lithium borofluoride are used as solutes. etc. are known.

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. However, in general, a solvent with a high dielectric constant has a high viscosity, and a solvent with a low viscosity has a low dielectric constant.

Therefore, by mixing a high viscosity solvent and a low viscosity solvent, a solvent with a high dielectric constant and low viscosity can be obtained.
■Although there is potential, an appropriate mixed solvent has not yet been found. Therefore, conventional non-aqueous electrolyte batteries have had problems with high rate discharge characteristics.

e→ Problem to be Solved by the Invention The problem to be solved by the invention is to improve the high rate discharge characteristics of a non-aqueous electrolyte battery.

B) Means for Solving the Problems The present invention uses a mixed solvent containing at least a small amount of propylene carbonate and triether as the solvent constituting the non-aqueous electrolyte.

(e) Effect A mixed solvent containing at least propylene carbonate and triny or chil dissociates the solute more easily than a single solvent or other mixed solvents (also, the energy for solute movement decreases, causing the negative electrode active material to dissociate). The reaction between the ions and the positive electrode active material is carried out smoothly.

(f) Example Examples of the first embodiment of the present invention will be described in detail below.

Example 1 A mixed solvent in which propylene carbonate and diethylene glycol dimethyl ether were mixed at a mixing ratio of 1:1 was used as a solvent, and 1 mol/l of lithium perchlorate as a solute was dissolved in this mixed solvent as an electrolyte. do.

The positive electrode is made of manganese dioxide heat-treated in a temperature range of 350 to 430°C as an active material, and this manganese dioxide is mixed with carbon powder as a conductive agent and fluororesin powder as a binder in a weight ratio of 85:10:5. The mixture was pressure-molded and heat-treated at 250 to 350°C, and the negative electrode was a lithium rolled plate punched out to the specified dimensions. A 120 mAH battery of the present invention is obtained. This battery is designated as A1.

Example 2 A battery of the present invention was prepared in the same manner as in Example 1 except that a mixed solvent of propylene carbonate and diethylene glycol diethyl ether at a mixing ratio of 1:1 was used as the solvent. This battery will be referred to as A2.

Comparative Example Next, in order to investigate the superiority of the battery of the present invention, a comparative battery (B) using propylene carbonate alone as a solvent, a comparative battery (B) using diethylene glycol dimethyl ether alone (Q, propylene carbonate and 1,2 A comparative battery was prepared using a mixed solvent with dimethoxyethane mixed at a mixing ratio of 1:1.Comparative battery tBl
(C)n is the same as in Example 1 except for the solvent.

FIG. 1 is a discharge characteristic diagram when these batteries were discharged at a constant resistance of 5000 at 25°C.

As is clear from FIG. 1, the battery of the present invention (A+) (A
2) has improved high rate discharge characteristics compared to the comparative battery (Bl fQ fD).

FIGS. 2 and 3 are diagrams showing the relationship between the mixing ratio of the mixed solvent and the discharge capacity of the battery in each example.

(G) Effects of the Invention As mentioned above, the gist of the present invention is to use a mixed solvent containing at least a small amount of propylene carbonate and triether as a solvent, and this mixed solvent is such that the solute easily dissociates, and Since the energy of solute movement is reduced and the reaction between the ions of the negative electrode active material and the positive electrode active material occurs smoothly, it is possible to obtain a non-aqueous electrolyte battery with excellent high rate discharge characteristics. This will greatly contribute to expanding the uses of seed batteries.

In the present invention, diethylene glycol dimethyl ether and diethylene glycol diethyl ether have been disclosed as examples of triethers, but dimethylene glycol dipropyl ether, trimethoxymethane, etc. can also be used.

[Brief explanation of the drawing]

FIG. 1 is a comparison diagram of the high rate discharge characteristics of the battery of the present invention and a comparative battery, and Figures 2 and 3 are diagrams showing the relationship between the mixing ratio of the mixed solvent and the discharge capacity of the battery of the present invention. (A1) (A2)...Battery of the present invention, tBl te
l fDl... Comparison battery.

Claims (1)

[Claims] (1) A negative electrode comprising a light metal such as lithium or sodium or an alloy thereof as an active material, a positive electrode, and a non-aqueous electrolyte comprising a solvent and a solute, wherein the solvent is at least propylene carbonate. A non-aqueous electrolyte battery characterized by being a mixed solvent containing triether.