JPS62143365A - Manufacture of organic electrolyte battery - Google Patents

Abstract

PURPOSE:To prevent an increase in internal resistance and a drop in discharge capacity at high temperature storage from occurring, by applying heat treatment to the pellet pressurized and molded to an active material inclusive of chalcopyrite after mixing a conductive agent or this agent and a binding agent under the specified temperature range in a state of the pellet alone or being molded as one body together with a metallic case. CONSTITUTION:A positive electrode is made up of molding such a pellet that is produced as pressurized and molded to an active material after mixing a conductive agent alone or this agent and a binding agent, with itself or together with a metallic case as one body, and it is subjected to heat treatment at a temperature range of 70-120 deg.C. With this heat treatment, the positive electrode 1 is mixed with a chalcopyrite 100pts.wt. and a graphite 10pts.wt. as a conductive agent and formed into a compact. Next, this positive electrode 1 is housed in a case 2 being nickeled to iron and, after being fitted with a positive electrode ring 3 consisting of stainless steel, it is pressurized again and unitized in this case. In addition, the positive electrode 1 unitized with the case is subjected to the heat treatment at the specified temperature under decompression (or under atmospheric pressure allowable).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing an organic electrolyte battery in which a positive electrode active material made of chalcopyrite alone or a mixture of chalcopyrite and a metal oxide is heat-treated.

Conventional technology Conventionally, this type of organic electrolyte battery uses metal oxides, sulfides, etc. as the positive electrode active material, lithium, aluminum, magnesium, or alloys containing these as the negative electrode active material, and uses pyrene carbonate, pyrene carbonate, etc. as the electrolyte. Inorganic salts such as lithium perchlorate and lithium boro7onide are dissolved in a single or mixed solvent of two or more of esters such as γ-butyrolactone, ethers such as 1゜2 dimethoxyethane, and 1,3 dioxolane. It has the characteristics of high energy density, self-discharge and leakage resistance.

So-called 3V class lithium batteries, which use carbon fluoride, manganese dioxide, or thionyl chloride for the positive electrode and lithium for the negative electrode, have already been put into practical use.

Meanwhile, progress is being made in the commercialization of 1.5v class lithium batteries for compatibility with existing batteries such as silver oxide batteries and mercury batteries.

In particular, lithium batteries that use chalcopyrite as the positive electrode active material use iron disulfide (F1382) and silver oxide (Cub).
Compared to the positive electrode active material, the voltage flatness and the swelling of the positive electrode as the discharge progresses are small.
This is disclosed in Publication No. 7764 and the like.

In addition, while taking advantage of iron disulfide and cupric oxide's high energy density, we developed chalcopyrite to overcome the drawbacks of a two-stage discharge pressure curve and large swelling of the positive electrode as discharge progresses. JP-A-58-19766 and JP-A-58-2060, which were improved by mixing
There is also an example in Publication No. 56.

Chalcopyrite is a natural product made by crushing natural ores, and C
There are synthetic products synthesized from u, Fe, S, Cu2 S + Fe S2, etc. Of these, synthetic products are usually used because natural products contain many impurities that adversely affect battery performance.

However, in either case, the stability against moisture is poor, and the iron content in chalcopyrite tends to be eluted in the presence of water. For this reason, conventional dehydration treatment conditions for positive electrodes using chalcopyrite are normal pressure and reduced pressure.
It was heat-treated at a temperature of about ℃.

Problems to be Solved by the Invention Even with such conventional synthetic products, there has been a problem of deterioration of battery performance, particularly a significant increase in internal resistance and decrease in discharge capacity during high-temperature storage.

The present invention is intended to solve such problems, and is aimed at heat-treating a positive electrode body.

Means to Solve the Problem In order to solve this problem, the present invention provides pellets made by pressure molding an active material containing chalcopyrite, a conductive agent alone or a mixture of a conductive agent and a binder. It is heat-treated in a temperature range of 70 to 12C) while integrally molded into a metal case.

As a result of various analyzes of batteries with performance deterioration caused by this configuration, the reason for the performance deterioration is not necessarily clear. Heat treatment at high temperatures of °C or higher will cause desorption of sulfur in chalcopyrite, oxidation of chalcopyrite, and sulfur in the active material will dissolve in the electrolyte in the battery, resulting in decomposition of the electrolyte and deposition on the lithium negative electrode. This is thought to be because precipitation becomes more likely to occur.

On the other hand, when the treatment is carried out at a low temperature of 70° C. or lower, it is difficult to remove water in chalcopyrite or pellets, and iron in the chalcopyrite is eluted by residual water. In addition, residual moisture reacts with lithium in the negative electrode. It is thought that this causes an increase in internal resistance and a decrease in discharge capacity.

According to the present invention, the oxidation of chalcopyrite, the desorption of sulfur, its elution into the electrolytic solution, and further its precipitation on the lithium negative electrode are suppressed, resulting in stable battery performance.

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

Example ■ In Fig. 1, 1 is a positive electrode and chalcopyrite is used. In this example, synthesized chalcopyrite was used, but 100 parts by weight of natural chalcopyrite may be used, and 10 parts by weight of graphite was used as a conductive agent. It is a molded product made by mixing.

Next, this positive electrode was housed in a case made of nickel-plated iron, and after a positive electrode ring 3 made of stainless steel was attached, it was again pressurized and integrated into the case.

Furthermore, the positive electrode integrated into the case was heat-treated for 12 hours at each temperature shown in the following table under reduced pressure (or normal pressure may be used).

In this case, only the positive electrode may be heat-treated and then integrated into the case.

Sample shop Heat treatment temperature 1 60 (°C) 4 12Q 4 is a sealing plate, and 5 is a negative electrode made of metal lithium that is pressed onto the inner surface of the sealing plate. 6 is an impregnated material made of polypropylene nonwoven fabric, 7 is a separator made of polypropylene microporous film, and perchloric acid is added to a solvent containing propylene carbonate and 1.2 dimethoxyethane mixed at a volume ratio of 1:1. A predetermined area is impregnated with an electrolytic solution in which 1 mol/l of lithium is dissolved. 8 is a gasket made of polypropylene.

The battery assembled as described above was subjected to a storage test at 60'C for 6 months.

Figures 2 and 3 show internal resistance changes due to storage tests and discharge capacity when 1 sKΩ discharge (1, ov termination) was performed at 20°C.

Example ■ A positive electrode consisting of 10 parts by weight of the chalcopyrite, 5 parts by weight of acetylene black as a conductive agent, and 6 parts by weight of 47-fluorinated ethylene/fluorinated propylene copolymer as a binder was used, but the same procedure as in Example was carried out. The battery was assembled and a storage test was conducted.

FIGS. 4 and 6 show the test results, and show changes in internal resistance and discharge capacity after a storage test of 6 months at 6Q°C.

Example (2) A battery was assembled and a storage test was carried out in the same manner as in Example (2) using a positive electrode consisting of 1 part by weight of chalcopyrite 50, 5 parts by weight of cupric oxide and 10 parts by weight of graphite. The results are shown in FIGS. 6 and 7 as above.

Example ■ 50 parts by weight of chalcobyrite, 60 parts by weight of cupric oxide,
Acetylene plaque 6 parts by weight, 4-fluorinated ethylene, 67
A battery was assembled in the same manner as in Example (2) using a positive electrode made of 6 parts by weight of dipropylene copolymer, and a storage test was conducted. The results are shown in FIGS. 8 and 9 as above.

From these figures, it is clear that using positive electrode pellets heat-treated at a temperature of 80 to 120°C results in less increase in internal resistance and less decrease in discharge capacity after storage, and the lower limit of the heat treatment temperature is determined by the moisture removal described above. From this point, it is 7oC.

By heat-treating the positive electrode formed by the effects of the invention in a temperature range of 70 to 120°C, it is possible to provide an organic electrolyte battery that eliminates internal resistance and capacity deterioration during high-temperature storage of the battery.

[Brief explanation of drawings]

FIG. 1 is a half-sectional view showing an organic electrolyte battery manufactured according to an embodiment of the present invention, and FIGS. 2 and 3 show the internal resistance and discharge capacity at the initial stage and after storage of the battery described in Example Figures 4 and 5 are diagrams showing changes in the internal resistance and discharge capacity of the battery described in Example H. Figures 6 and 7 are diagrams showing the internal resistance of the battery described in Example ■. , Figures 8 and 9 are diagrams showing changes in discharge capacity at 60°C,
FIG. 3 is a diagram showing changes in internal resistance and discharge capacity due to storage for six months. 1...Positive electrode, 2...Case, 3...
Positive electrode ring, 4... Sealing plate, 6... Negative electrode, 6... Impregnating material, 7... Separator, 8... Gasket. Name of agent: Patent attorney Toshi Nakao and one other person?・−Booth 3−・−Positive ring °. 4...-Sealing root 5---Choice 7㉷F 6°°-Chopsticks r immersed 7---Here's the rotor Fig. 1 6゛-
Kasbu throat Figure 2 Processing Ei Pe ((°C Figure 4 Figure 5 Processing Bad sentence (C) Figure 6 Figure 7 so too 150
200 processing warm side (C)

Claims (2)

[Claims] (1) A method for manufacturing a battery consisting of a positive electrode containing chalcopyrite (CuFeS_2_-_x, where 0<x≦0.24), a negative electrode using a light metal as an active material, and an organic electrolyte, wherein the positive electrode is an active material. Pellets obtained by pressure molding a conductive agent alone or a mixture of a conductive agent and a binder are molded into a metal case or molded together at 70 to 120°C.
A method for producing an organic electrolyte battery, characterized by heat treatment in a temperature range of . (2) The method for manufacturing an organic electrolyte battery according to claim 1, wherein the conductive agent is made of graphite or carbon.