JPS5836826B2 - Manufacturing method of organic electrolyte battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an organic electrolyte battery using a light metal as a negative electrode active material. The purpose is to fix the battery and improve the leakage resistance of the battery.

Another object of the present invention is to improve the discharge start-up and voltage flatness of a battery using a gelled electrolyte.

Currently, the power supplies for electronic devices on the market are:
Silver batteries and mercury batteries are the mainstream, but these batteries inherently have creep properties because they use an aqueous solution of caustic potash or caustic soda as an electrolyte.

In addition, due to the interaction with the potential of the battery, if stored for a long time even at room temperature, leakage may occur, potentially causing serious damage to the equipment used.

On the other hand, organic electrolyte batteries that use light metals as negative electrode active materials are nonaqueous and use solvents with high viscosity, so they are extremely unlikely to leak compared to batteries that use alkaline electrolytes; Occasionally leakage occurred, and it was not completely eliminated.

Leakage is something that equipment manufacturers hate the most because it has a serious impact on the equipment used, and is more important than the performance of the battery in question.

Therefore, in order to eliminate liquid leakage, it is best to immobilize the electrolyte that exists freely.

When the electrolyte is immobilized, the ionic conductivity of the solution decreases,
Although high-rate discharge performance deteriorates as a result, this is not a problem because recent electronic components are moving towards power saving.

As a method for immobilizing an electrolytic solution, the present inventors previously proposed a method of forming a gel using polymethyl methacrylate.

The method for producing the gel is to add 20 to 50% of polymethyl methacrylate to an organic electrolyte that dissolves polymethyl methacrylate, such as propylene carbonate or γ-butyrolactone, in which lithium borofluoride or lithium perchlorate is dissolved.
Add 50% by weight and heat on an oil bath at 90-100°C.

This turns the whole into a sol, and when this is cooled, a jelly-like gel is formed.

This gel has sufficient flexibility even when stored at 60° C., and no syneresis phenomenon is observed, so batteries manufactured using this gel do not leak.

The performance of this battery varies greatly depending on how the positive electrode is treated.

In general, organic electrolyte batteries have the disadvantage of high internal impedance, but when using a gel electrolyte, simply interposing it between the positive and negative electrodes will generally prevent the active material powder from containing a conductive material and a binder. In addition, the contact between the positive electrode obtained by molding and the electrolyte is insufficient, resulting in poor discharge rise and flat voltage, in particular.

The present invention solves the above-mentioned drawbacks by impregnating the positive electrode with a hot sol during the process of obtaining a gel electrolyte.

The present invention will be described below with reference to drawings showing embodiments thereof.

FIG. 1 shows the schematic structure of the carbon-lithium fluoride battery used in the examples.

In the figure, 1 is a negative electrode constructed by pressing a lithium sheet with a size of 20 x 20 mm and a thickness of 1 mm onto a nickel grid 2. 3 is a negative electrode composed of 100 parts by weight of fluorocarbon, 10 parts by weight of acetylene black, and a fluororesin bond. A mixture containing 20 parts by weight of the adhesive was molded into a size 20 x 20 mm and a thickness of 0.8 mm with a titanium grid 4 as the center, and the filling amount was 250 m.
This is the positive electrode of Ah.

5 is a separator made of polypropylene.

6 is a cylindrical glass cell with a thickness of 2 mm, an inner diameter of 26 mm, and a depth of 60 mm.

Pre-dried microspheres of polymethyl methacrylate with a molecular weight of 700,000 to 750,000 (particle size 0.05 to 0.15 mm:
3.6 g of the above-mentioned power generation element were stored in a cell 6, 15 cc of a propylene carbonate electrolyte of lithium borofluoride with a concentration of 1 mol/l was injected, and the cells were heated in an oil bath at 95 to 97°C for 10 to 12 g.
When heated for a minute, the electrolyte becomes a sol.

At this point, the entire power generation element is impregnated at a reduced pressure of 30 mmHg for 1 minute, and the hot sol of the electrolyte permeates into the positive electrode.

Thereafter, a gel-like organic electrolyte having a polymer concentration of 24% by weight was obtained by cooling.

With the above configuration, the power generating element is immersed in a heated sol-like organic electrolyte, impregnated with the sol-like electrolyte under reduced pressure, and cooled to obtain a gel-like battery. The gel-like battery obtained by immersing the battery in water and cooling it is referred to as B.

The following table shows the electrical characteristics of each battery at 20°C, and FIG. 2 shows the discharge characteristics at 20°C and 5KΩ.

As is clear from these results, a gel battery using a positive electrode impregnated with a thermosol electrolyte has superior electrical characteristics, and also superior discharge characteristics in terms of discharge rise and flat voltage.

Generally, in batteries using liquid organic electrolytes, the flat voltage is the same even if there is a difference in impedance.
It turns out that this kind of gel battery is different.

Several methods can be considered for producing gel electrolytes.

Therefore, there are methods of impregnating a positive electrode with a thermosol electrolyte under reduced pressure and cooling it to obtain a positive electrode containing gel, methods of immersing a positive electrode in a thermosol electrolyte and cooling it to obtain a gel-adhered positive electrode, and In this section, we will explain the comparative results for batteries that simply stack a gel electrolyte and a negative electrode.

FIG. 3 shows a carbon monolithium fluoride battery constructed in a flat shape.

In the figure, 8 is a case made of stainless steel, 9 is a sealing plate made of the same material, and 10 is a grid welded to the inner surface of the sealing plate, and a lithium sheet 11 is pressure-bonded to the surface of this grid.

12 is a positive electrode containing gel, 100 parts by weight of carbon fluoride, 10 parts by weight of acetylene black, and fluororesin binder 2.
0 parts by weight of mixture 0. 26 g was molded into a disk shape and impregnated with gel by the following method.

That is, 3.4 microspheres (particle size 0.05-0.15u+) of polymethyl methacrylate with a molecular weight of 700,000 to 750,000
A weighing bottle containing 5 g and 15 cc of 1 mol/l lithium borofluoride propylene carbonate electrolyte was heated in an oil bath to
The disk-shaped molded body was heated to 7° C. to form a sol, immersed in this sol, impregnated for 1 minute at a reduced pressure of 30 mmHg, taken out, cooled, and formed into a positive electrode containing a gel with a polymer concentration of 23% by weight. did.

This positive electrode was placed on a titanium grid 13 welded to the inner surface of the case 8.

On the other hand, 3.0 g of the same polymethyl methacrylate was added to 12 CC of the above electrolyte and heated in the same manner to form a sol.
It was poured into an aluminum container and cooled at 20° C. for 12 hours to produce a jelly-like gel electrolyte with a polymer concentration of 25% by weight, which was cut into a predetermined size and placed on the lithium negative electrode 11.

14 is this electrolyte layer.

At the same time, the polypropylene separator 15 was also wetted with hot sol in advance and then slowly cooled before use.

16 is a polypropylene gasket.

Battery a according to the present invention manufactured by this method, battery b using a gel-adhered positive electrode obtained by immersing the positive electrode in a thermosol electrolyte and cooling it, and battery b using a gel-attached positive electrode obtained by immersing the positive electrode in a thermosol electrolyte and cooling it, and a battery b in which a gel electrolyte and a negative electrode are placed on the molded positive electrode as it is. Let C be the battery installed.

Table 2 shows the electrical properties of these cells at 20°C.

Moreover, FIG. 4 shows the characteristics when discharging at 20°C and IIKΩ.

As is clear from these results, the battery a according to the present invention
is excellent in battery impedance, short circuit current, discharge rise, and flat voltage, and has a discharge capacity of 1307FL.
It can be seen that it has excellent performance with Ah and utilization rate of 76%.

As described above, according to the present invention, a leak-free battery having excellent performance can be obtained.

[Brief explanation of the drawing]

Figure 1 is a schematic vertical cross-sectional view of a lithium carbon fluoride battery used in an example of the present invention, Figure 2 is a diagram showing its discharge characteristics, and Figure 3 is a diagram showing its discharge characteristics.
The figure is a longitudinal cross-sectional view of a flat battery, and FIG. 4 shows its discharge characteristics. 1, 11... Negative electrode, 3, 12... Positive electrode, 7, 14... Electrolyte.

Claims (1)

[Claims] 1. A method for manufacturing a battery having a negative electrode using a light metal as an active material, an organic electrolyte gelled with polymethyl methacrylate, and a positive electrode, the method comprising a thermosol obtained by heating polymethyl methacrylate and the organic electrolyte. A method for producing an organic electrolyte battery, comprising the step of impregnating a positive electrode with under reduced pressure.