JPS6164081A - Nonaqueous electrolyte battery - Google Patents

Abstract

PURPOSE:To improve the high-rate discharge characteristic of a nonaqueous electrolyte battery by using a solvent mixture containing propylene carbonate and a carbonic ester as the solvent and using lithium trifluoromethane sulfonate as the solute. CONSTITUTION:A liquid electrolyte is prepared by dissolving, for example, 1mol/l of lithium trifluoromethane sulfonate used as the solute in a solvent mixture prepared by combining propylene carbonate and methyl acetate in a ratio of 1:1. A positive electrode is made by combining manganese dioxide thermally treated at 350-430 deg.C used as the active material with carbon powder used as the conductive material and fluorine resin powder used as the binder in a ratio by weight of 85:10:5: and then subjecting the thus prepared mixture to compression molding and thermal treatment at 250-350 deg.C. A negative electrode with given dimensions is stamped out from a rolled lithium plate. A nonaqueous electrolyte battery with 20.0mm diameter, 2.5mm thickness and 120mAH capacity is produced by using the above parts.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention provides a negative electrode using lithium or a lithium alloy as an active material, a positive electrode using a metal oxide, sulfide, halide, etc. as an active material, The present invention relates to a non-aqueous electrolyte battery equipped with a non-aqueous electrolyte consisting of 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-'52866, globylene carbonate, r-butyrolactone, dimethoxyethane, dioxolane, tetrahydro-7ran, etc. are used as solvents, and lyticum perchlorate, lyticum perchlorate, etc. are used as solutes. Lithium chloride is known.

Now, in recent years, with the expansion of the field of application of this type of battery, 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, it is possible to obtain a solvent having a high dielectric constant and low viscosity by mixing a high viscosity solvent and a low viscosity solvent, but an appropriate mixed solvent has not yet been found. For this reason, conventional non-aqueous electrolyte batteries have problems with high rate discharge characteristics.

(c) Problems to be Solved by the Invention The problems to be solved by the present invention are to improve the high rate discharge characteristics of non-aqueous electrolyte batteries.

B) Means for Solving the Problems The present invention uses a mixed solvent containing propylene carbonate and a carboxylic acid ester as a solvent constituting a non-aqueous electrolyte. In addition, lithium trifluoromethanesulfonate is used as a solute.

(e) Effect: In a mixed solvent containing a carbonate and a carboxylic acid ester, the solute dissociates more easily than in a single solvent or a mixed solvent, and the energy for moving the solute decreases, causing ions of the negative electrode active material to dissociate. The reaction between the positive electrode active material and the positive electrode active material is carried out smoothly.

Further, if lithium trifluoromethanesulfonate is used as a solute in a mixed solvent containing probilene/carbonate and a carboxylic acid ester, the capacity can be increased compared to the case of using other solutes.

Note that methyl acetate, methyl formate, etc. are used as the carboxylic acid ester.

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

Example 1 Propylene carbonate and methyl acetate were used as solvents at 1
; Using a mixed solvent mixed at a mixing ratio of 1.

An electrolytic solution is prepared by dissolving 1 mol/l of lithium trifluoromethanesulfonate as a solute in this mixed solvent.

7: E, Otori! Manganese dioxide heat-treated at a temperature range of 150 to 450°C is used as an active material, and this manganese dioxide and
A mixture of carbon powder as a conductive agent and fluorocarbon resin powder as a binding agent in a weight ratio of 85=10=5 was pressure-molded and heat-treated at 250-350°C, and f:L The poles were made by punching lithium rolled plates into specified dimensions, with a diameter of 20.0 mm, thickness of 2.5 mm, and battery capacity of 12 mm.
A battery of the present invention of 01 nAH is obtained. This battery is designated as A1.

Example 2 Propylene carbonate and methyl formate were used as solvents at 1
Using a mixed solvent mixed at a mixing ratio of =1.

The electrolyte was prepared by dissolving 1 mol/l of lithium trifluoromethanesulfonate as a solute in this mixed solvent, and the rest was the same as in Example 1. This invention battery is designated as A2.

Next, in order to demonstrate the superiority of the battery of the present invention, various comparison batteries were prepared with various solvents and solutes.

The comparative battery was the same as Example 1 except for the solvent and solute.

Comparative Example 1 Propylene carbonate was used alone as a solvent, and an electrolytic solution was prepared by dissolving 1 mol/l of lithium trifluoromethanesulfonate as a solute in this solvent. This comparison battery is designated as B.

Comparative Example 2 Methyl acetate was used alone as a solvent, and an electrolytic solution was prepared by dissolving lithium trifluoromethanesulfonate as a solute at 1 mol/l in this solvent.

This comparative battery is designated as O.

Comparative Example 3 An electrolytic solution was prepared by dissolving 1 mol/l of lithium trifluoromethanesulfonate as a solute in a mixed solvent of equal volume of probile/carbonate and dimethoxyethane as a solvent. This comparison battery is designated as D.

Comparative Example 4 Propylene carbonate and methyl acetate were used as solvents at 1
:A mixed solvent mixed at a mixing ratio of 1? use.

Add 1 mol/mol of lithium perchlorate to this mixed solvent as a solute.
l The dissolved material is used as an electrolyte. This comparison battery is designated as E.

Comparative Example 5 Propylene carbonate, methyl formate and 1F as solvents
Using a mixed solvent mixed at a mixing ratio of r:1:1.

An electrolytic solution is prepared by dissolving lithium perchlorate (t-17 l/l) as a solute in this mixed solvent. Compare this battery? shall be.

Figure 1 shows that these batteries were heated at 25℃ immediately after assembly.
A discharge characteristic diagram when discharging with a constant resistance of 000 is shown. Second
The figure and FIG. 3 show the relationship between the mixing ratio of the mixed solvent and the battery discharge capacity in the battery of the present invention.

(g) Effect of the invention As is clear from FIG. 1, the batteries of the invention (A1) (A2)
It can be seen that among the comparative batteries) to (PI) are superior in high rate discharge characteristics.

Considering the reason for this, firstly, the mixed solvent 7 in the present invention, that is, the mixed solvent containing propylene carbonate and carboxylic acid ester, easily dissociates the solute.

The energy of solute movement is reduced, and the reaction between lithium ions and the positive bridge active material is carried out smoothly, and especially when lithium trifluoromethanesulfonate is used as a solute in the above-mentioned mixed solvent.

Although the reason is not clear compared to the case where lithium perchlorate is used as the solute, the synergistic effect between the solvent and the solute, such as the viscosity of the electrolyte, has a favorable effect on conductivity and dielectric constant. it is conceivable that.

[Brief explanation of the drawing]

Figure 1 is a diagram comparing the discharge characteristics of the battery of the present invention and the comparison battery, $2
3 and 3 are diagrams showing the relationship between the mixing ratio of the mixed solvent and the battery discharge capacity in the battery of the present invention. (A+) (A2)...Battery of the present invention, @)~(G)...
・Comparison battery.

Claims (1)

[Claims] (1) A device comprising a negative electrode using lithium or a lithium alloy as an active material, a positive electrode, and a non-aqueous electrolyte comprising a solvent and a solute, the solvent being a mixed solvent containing propylene carbonate and a carboxylic acid ester. A non-aqueous electrolyte battery, wherein the solute is lithium trifluoromethanesulfonate.