JPH0254625B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvement of an organic electrolyte battery using lithium as a negative electrode active material, and aims to improve discharge performance.

The discharge reaction of an organic electrolyte battery using lithium as the negative electrode active material is a reaction in which lithium ions move to the positive electrode side and generate reaction products within the positive electrode.
As the discharge progresses, the positive electrode swells and absorbs the electrolyte, reducing the electrolyte in the separator, inhibiting the progress of the discharge reaction, and causing a decrease in discharge voltage and an increase in internal resistance.

In view of such circumstances, the present invention has been developed in an organic electrolyte battery using lithium as a negative electrode active material, by adding sodium silicate or a mixture of magnesium silicate and sodium polyacrylate to the electrolyte solution, thereby improving the efficiency of the battery as the discharge progresses. This prevents the electrolyte from being absorbed into the positive electrode side and prevents the electrolyte in the separator from running out even at the end of discharge, thereby improving discharge performance.

The reason why the discharge performance is improved by adding sodium silicate or a mixture of magnesium silicate and sodium polyacrylate to the electrolytic solution is not necessarily clear, but it is thought to be as follows.

In other words, sodium silicate and magnesium silicate fix sodium polyacrylate, and sodium polyacrylate increases the viscosity of the electrolyte.
This is thought to be due to preventing the electrolyte in the separator from moving toward the positive electrode.

In the present invention, the mixing ratio of sodium silicate or magnesium silicate and sodium polyacrylate is preferably in the range of 2:1 to 10:1 by weight, and the amount of the mixture added to the electrolyte is It is preferable to set it to 5 to 20% (weight %, the same applies hereinafter). This is based on the viewpoint that the desired effect can be achieved by adding the mixture, and the addition does not cause any adverse effects.

In the organic electrolyte battery of the present invention, as the positive electrode active material, for example, manganese dioxide, iron sulfide, copper sulfide, copper oxide, carbon fluoride, silver chromate, etc. are used, and as the electrolyte, for example, propylene carbonate, γ- butyrolactone, tetrahydrofuran,
A solution in which an electrolyte such as lithium perchlorate or lithium borofluoride is dissolved in a solvent such as 1,2-dimethoxyethane or 1,3-dioxolane alone or in a mixture of two or more is used.

Next, the present invention will be explained with reference to Examples.

FIG. 1 is a sectional view showing a flat organic electrolyte battery. In FIG. 1, 1 is a positive electrode, 2 is a stainless steel mesh, and 3 is a positive electrode can that also serves as a positive terminal. 4 is a separator made of polypropylene nonwoven fabric or the like, and 5 is a negative electrode can that also serves as a negative electrode terminal. 6 is a stainless steel mesh spot welded to the inner surface of the negative electrode can 5, and 7 is a negative electrode, which is crimped to the mesh 6. 8 is an annular gasket made of synthetic resin such as polypropylene.

The positive electrode 1 was prepared by filling a mold with 290 mg of a mixture consisting of 100 parts by weight of manganese dioxide (parts by weight, the same applies hereinafter), 10 parts of phosphorous graphite, and 2 parts of polytetrafluoroethylene, which had been heat-treated at 400°C for 4 hours. , 1t/cm ² , and then a stainless steel net 2 was placed on the preformed layer, and the diameter was 16 mm and the thickness was
Pressure molded to 0.5mm, negative electrode 7 has a diameter of 14mm,
It is made of a lithium plate with a thickness of 0.2 mm, and the battery has a diameter of 20 mm.
The thickness is 1.6mm.

The electrolyte is a mixed solvent of propylene carbonate and 1,2-dimethoxyethane with a volume ratio of 1:1, in which 1 mole of lithium perchlorate is dissolved. A mixture of sodium acrylate and sodium acrylate in a weight ratio of 5:1 is injected in various amounts.
The injection amount was 75μ for both batteries.

-10℃, 300Ω at 80% discharge of the above battery
The closed circuit voltage was measured after discharging for 5 seconds.

The results are shown in FIG.

As shown in Figure 2, the amount of the mixture of sodium silicate and sodium polyacrylate
Closed circuit voltage is high in the 20% range.

Next, mixtures with various mixing ratios of sodium silicate and sodium polyacrylate were prepared, and 10% of the mixture was added to the same electrolyte as above,
A battery similar to the above was manufactured using the same,
-10 at 80% discharge for those batteries
The closed circuit voltage was measured after discharging for 5 seconds at 300Ω at °C.
The results are shown in FIG. In Fig. 3, sodium silicate is indicated by SS, and sodium polyacrylate is indicated by SPA.

As shown in Figure 3, the mixing ratio of sodium silicate and sodium polyacrylate is 2:
The closed circuit voltage is high in the range of 1 to 10:1.

Note that similar results were obtained when magnesium silicate was used instead of sodium silicate.

That is, batteries similar to those described above were manufactured except that a mixture of magnesium silicate and sodium polyacrylate at a weight ratio of 5:1 was added to the same electrolytic solution in various amounts, and the mixture was used. , -10℃ at 80% discharge for those batteries,
The closed circuit voltage was measured after discharging at 300Ω for 5 seconds. The results are shown in FIG.

As shown in Figure 4, the amount of the mixture of magnesium silicate and sodium polyacrylate added was 5.
High closed circuit voltage in the range ~20%.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the organic electrolyte battery of the present invention, and FIG. 2 is a diagram showing the relationship between the amount of a mixture of sodium silicate and sodium polyacrylate added to the electrolyte and the closed circuit voltage. , Figure 3 shows the relationship between the mixing ratio of sodium silicate (SS) and sodium polyacrylate (SPA) and the closed circuit voltage, and Figure 4 shows the relationship between the mixture ratio of sodium silicate (SS) and sodium polyacrylate (SPA) and the electrolyte solution of the mixture of magnesium silicate and sodium polyacrylate. FIG. 3 is a diagram showing the relationship between the amount of addition and the closed circuit voltage. 7...Negative pole.

Claims (1)

[Scope of Claims] 1. An organic electrolyte battery using lithium as a negative electrode active material, characterized in that a mixture of sodium silicate or magnesium silicate and sodium polyacrylate is added to the electrolyte. 2 The mixing ratio of sodium silicate or magnesium silicate and sodium polyacrylate is 2:1 to 10:1 by weight, and the amount of the mixture added to the electrolyte is 5 to 20% by weight. The organic electrolyte battery according to scope 1.