JPS5836827B2 - 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 a polymethacrylic acid alkyl ester.

Silver and mercury batteries are currently used as the main power source for small electronic devices, but in addition to using an alkaline electrolyte that inherently has cleaving properties, the potential of the battery has a synergistic effect. However, it is very difficult to achieve complete leak-free operation over a long period of time, and leakage causes serious damage to equipment.

Therefore, the present inventors previously proposed a method of gelling and immobilizing 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 leak even when stored at high temperatures can be obtained.

Particularly in the current situation of small and thin batteries with high energy density, organic electrolyte batteries are advantageous from the above points as well.

The polymethacrylic acid alkyl ester used here includes propylene carbonate, which is commonly used as an electrolyte,
Polymethyl methacrylate and polyethyl methacrylate are more suitable because of their compatibility with γ-butyrolactone and the like and ease of gelation.

However, it is known that methacrylic acid-based polymers such as polymethyl methacrylate and polyethyl methacrylate have high adhesive properties due to their molecular structure.

On the one hand, this is advantageous in terms of battery characteristics because the gel sandwiched between the positive and negative electrodes has good contact with both electrode plates, but on the other hand, there are the following problems.

In other words, in order to obtain a gel electrolyte using this type of polymer, it is necessary to heat the organic electrolyte and polymer to a temperature of 80 to 90°C to create a thermosol, which is then poured into a petri dish and cooled. be.

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 when it is made of a single polymer, and viscoelastic factors come into play, especially when using manufacturing jigs and tools, such as gel. It sticks to the petri dish in which it is placed, a cutting jig, a clamping jig such as tweezers, etc., and it is extremely difficult to maintain and handle the battery material in a predetermined shape as a prick.

As a result, the shape of the gel electrolyte layer is not constant, resulting in variations in electrical characteristics and poor discharge characteristics.

The present invention eliminates the above-mentioned conventional drawbacks and simplifies the manufacturing process of gel electrolytes.

That is, in the present invention, a porous body of polymethacrylic acid alkyl ester is disposed within a battery, for example, on the positive electrode, an organic electrolyte is injected into the porous body, and the electrolyte is gelled by heating after sealing the battery. .

According to this method, a gel electrolyte having appropriate elasticity and good adhesion to the positive and negative electrodes can be obtained, and a battery of constant quality can be manufactured much more easily than in the past.

If the above-mentioned heating temperature is high, gelation will be completed in a short time, but if it is too high, it will have a negative effect on the sealing ring, etc.
A temperature of 0 to 60°C is suitable.

Suitable heating times are about 10 minutes at 90°C and about 10 hours at 60°C.

The present inventors have also proposed a method in which an electrolyte in which polymethacrylic acid alkyl ester particles are dispersed is injected into a battery and then heated to gel. However, in this method, the polymer absorbs the electrolyte. Before it becomes a thermosol, the electrolyte exists freely within the battery, so it circulates around the gap between the sealing plate and the gasket, for example, and this liquid is absorbed by the polymer and does not participate in becoming a thermosol. This solution was often present as it is, and this solution sometimes leaked during high-temperature storage of batteries, so it was not sufficient.

In the present invention, most of the electrolyte is held in a porous body of polymer, and the electrolyte is completely turned into a gel-like electrolyte by heating, so that there is no free liquid involved in leakage, and no leakage occurs.

Furthermore, this gel electrolyte has heat resistance, and the gel maintains its elasticity up to a certain temperature and does not cause syneresis.

Embodiments of the present invention will be described below with reference to the drawings.

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 containing 100 parts by weight of carbon fluoride, 10 parts by weight of acetylene black, 8 parts by weight of SBR binder, and a molecular weight of 7.
0.28 g of a mixture of 15 parts by weight of polymethyl methacrylate having a particle size of 0.000000 to 0.750000 and a particle size of 0.05 to 0.15 ixi was formed into a disk shape, and it was pressed onto the titanium grid 6 welded to the inner surface of the case 1. There is.

This battery was assembled as follows.

First, a separator 7 made of a polypropylene nonwoven fabric and a disk made of a sintered porous body (porosity about 45%) of polymethyl methacrylate particles are placed on the positive electrode in the case, and then
mol/t of lithium borofluoride dissolved in propylene carbonate 0. After injecting 25 CC, the sealing plate to which the negative electrode was bonded and the polypropylene gasket 8 were combined into the case 1 and sealed by caulking.

Thereafter, aging was performed at 80° C. for 1 hour to gel the electrolyte within the battery.

9 is an electrolyte layer in which a porous material of polymethyl methacrylate absorbs an electrolyte and becomes a gel.

Note that a part of the electrolyte injected into the case permeated into the porous positive electrode and gelled together with polymethyl methacrylate in the positive electrode.

When the battery manufactured as described above was disassembled, there was no free electrolyte in the gap between the sealing plate and the packing.

In the above example, a sintered porous body of polymethyl methacrylate was used, but in addition, tetrahydrofuran, methyl ethyl ketone, 1,3-dioxolane, 1, When a predetermined amount of polymethyl methacrylate is dissolved in 2-dimethoxyethane and a conventional liquid retaining material such as polypropylene nonwoven fabric or cotton is immersed in this solution and heated, the low boiling point solvent will evaporate. A porous body of polymethyl methacrylate is obtained using nonwoven fabric, cotton, or the like as a base material.

A similar battery was constructed using these, and satisfactory results were obtained.

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 5KΩ at 20°C are shown in Figure 2.

Battery B is made by adding polymethyl methacrylate to propylene carbonate in which 1 mol/t of lithium borofluoride is dissolved to give a concentration of 24% by weight, heating the mixture to 80 to 90°C to create a thermosol, which is then cooled. After that, the gel electrolyte 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.

Claims (1)

[Scope of Claims] 1. A method for manufacturing 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, the method comprising: A method for manufacturing a battery, comprising injecting an organic electrolyte into a porous body of acid alkyl ester, and heating the electrolyte after sealing the battery to gel the electrolyte. 2. The method for manufacturing a battery according to claim 1, wherein the polymethacrylic acid alkyl ester is polymethyl methacrylate or polyethyl methacrylate.