JPS5836828B2 - Battery manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a battery using an organic electrolyte gelled with polymethacrylic acid alkyl ester.
The purpose is to simplify the manufacturing process of gel electrolyte and provide a battery with excellent performance.

Silver or mercury batteries are the main power sources for current small electronic devices, but these use an alkaline electrolyte that inherently has creep properties, and the potential of the battery has a synergistic effect. It is extremely difficult to achieve complete leak-free operation over a long period of time, and leakage causes serious damage to equipment.

As electronic devices become smaller and more power efficient, batteries are also desired to be smaller and have higher energy density.

Therefore, the present inventors proposed a method of gelling the electrolyte of an organic electrolyte battery using a light metal such as lithium as a negative electrode active material with a polymethacrylic acid alkyl ester.

According to this method, an organic electrolyte battery that does not cause leakage even at high temperatures can be obtained.

As the polymethacrylic acid alkyl ester used here, polymethyl methacrylate and polyethyl methacrylate are used because of their compatibility with propylene carbonate, γ-butyrolactone, etc., which are commonly used as electrolytes, and their ease of gelation. more suitable.

This type of methacrylic acid-based polymer has high adhesive properties due to its molecular structure.

This has contradictory advantages and disadvantages in terms of battery manufacturing and performance.

That is, when the gel electrolyte made of the above-mentioned polymer is interposed between the positive and negative electrodes, it has good contact and adhesion with both electrode plates, so that it brings about advantageous results in battery characteristics.

However, in order to obtain a gel electrolyte using this polymer, the organic solvent in which the supporting salt is dissolved and the polymer must be mixed at a concentration of 80 to 90%.
It required a process of heating to ℃ to create a thermosol, pouring it into a petri dish, etc., and cooling it.

In the manufacturing process where a thin piece of gel is cut into a predetermined shape and inserted between the positive and negative electrodes, gel is different from a single polymer, and viscoelastic factors come into play. It tends to stick to the petri dish in which it is placed, the cutting jig, or the holding jig such as a pin motte, making it extremely difficult to handle it as a battery material while keeping it in a predetermined shape.

For this reason, the shape of the gel electrolyte layer is not constant, resulting in variations in electrical characteristics or deterioration.

The present invention uses a polymethacrylic acid alkyl ester, an organic solvent that can form a gel alone with this polymer, such as propylene carbonate, γ-butyrolactone, a low boiling point solvent that dissolves the polymer and is compatible with the organic solvent, and a supporting salt. A paste-like liquid is created by mixing the mixture, and the low-boiling point solvent is evaporated and removed by heating or depressurization, and then replaced with the low-boiling point solvent to form a gel-like liquid based on propylene carbonate or γ-butyrolactone. Characterized by obtaining electrolytes.

According to the present invention, a gel electrolyte similar to the conventional one can be obtained by applying the pasty liquid onto, for example, the positive electrode and removing the low boiling point solvent by heating or reducing pressure.

Furthermore, the gel electrolyte can be produced easily and regularly without any complications unlike the conventional method.

Examples of the present invention will be described below.

FIG. 1 shows a carbon fluoride-lithium battery.

In the figure, 1 is a case made of stainless steel, 2 is a sealing plate made of the same material, and 3 is a grid welded to the inner surface of the sealing plate, and a negative electrode lithium sheet 4 is pressure-bonded to the surface of this grid.

5 is a positive electrode, which contains 100 parts by weight of carbon fluoride, 10 parts by weight of acetylene blank, 8 parts by weight of SBR resin binder, and beads of polymethyl methacrylate with a molecular weight of 700,000 to 750,000 and a particle size of 0.05 to 0.15M. 15 parts by weight mixture 0.28
1 into a disk shape, and in a dry atmosphere, 1 mol/l
After injecting 160 μl of a propylene carbonate electrolyte in which lithium borofluoride was dissolved, the gel was heated to 80°C for 1 hour to form a gel. be.

7 is a gel electrolyte, 5 parts by weight of polymethyl methacrylate;
25 parts by weight of carbon propylene, 2.4 parts by weight of lithium borofluoride
parts by weight and 4 parts by weight of methyl ethyl ketone were thoroughly mixed to form a paste, and after coating on the above positive electrode, it was heated at 45°C for 30 minutes.
It was formed by evaporating methyl ethyl ketone under reduced pressure to WHr.

After forming the positive electrode and the electrolyte layer containing the gel electrolyte in the case 1 in this way, the sealing plate 2 to which the negative electrode is bonded is assembled and sealed by caulking.

Note that 8 is a polypropylene separator interposed between the electrolyte layer and the negative electrode, and 9 is a polypropylene gasket.

In the examples, propylene carbonate was used as the organic solvent constituting the electrolyte, which together with γ-butyrolactone is a stable solvent with a high boiling point exceeding 200°C.
The vapor pressure at 5°C is also 1wII. At H1 or less, the amount of evaporation caused by the pressure reduction operation is negligible.

Methyl ethyl ketone was used in the examples as a low boiling point solvent, but acetone, tetrahydrofuran, 1,3-dioxolane, Dimethoxyethane and the like are used.

Regarding the battery A of the above example and the conventional battery B, 20
The following table shows a comparison of the electrical properties at 20°C, and the discharge characteristics at 5 K and Q at 20°C are shown in Figure 2.

Battery B is made by adding polymethyl methacrylate to a concentration of 24% by weight to propylene carbonate in which 1 mol/l of lithium borofluoride is dissolved, heating it to 80 to 90°C to create a thermosol, and cooling this. After that, the gel electrolyte layer was cut into a predetermined size, and the positive electrode was impregnated with the above thermosol under reduced pressure to contain the gel electrolyte.

As described above, according to the present invention, a battery with excellent electrical characteristics and discharge characteristics can be obtained more easily and stably than in the past.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of a battery used in an example of the present invention;
The figure shows the discharge characteristics of the battery. 4...Negative electrode, 5...Positive electrode, 7...
...Gel electrolyte layer.

Claims (1)

[Scope of Claims] 1. A method for producing a battery having a negative electrode using a light metal as an active material, a positive electrode, and an organic electrolyte gelled with polymethacrylic acid alkyl ester, polymethacrylic acid alkyl ester, polymethacrylic acid alkyl ester, etc. A gel is formed by removing the low boiling point solvent from a pasty liquid containing an organic solvent that can form a gel alone with the alkyl ester, a low boiling point solvent that dissolves the polymethacrylic acid alkyl ester, and a supporting salt that is compatible with the organic solvent. A method for manufacturing a battery, comprising a step of obtaining an electrolyte. 2. The method for manufacturing a battery according to claim 1, wherein the polymethacrylic acid alkyl ester is polymethyl methacrylate or polyethyl methacrylate.