JPH07153456A - Manufacture of positive electrode material for battery - Google Patents

Abstract

PURPOSE:To apply a large quantity of doping in a short manufacturing period by drying a solution film obtained by spreading or coating a solution dissolved with a conductive polymer material and a dopant precursor. CONSTITUTION:An oxidant is added under the low-temperature condition to an aqueous solution of an acid conductive polymer material to obtain a conductive polymer material soluble in an organic solvent. This conductive polymer material and a dopant precursor soluble in an organic solvent are dissolved in the organic solvent to obtain a mixed solution. This mixed solution is spread or applied on a substrate, then it is heated to remove the solvent, and a film is obtained. A nonaqueous electrolytic material 2 is sandwiched and fixed between a positive electrode material 1 for a battery obtained when the film is processed and a negative electrode 3, then it is stored in a case 4, a positive lead 5 is connected to the positive electrode material 1, and a negative electrode lead 6 is connected to the negative electrode 3 to obtain the battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a positive electrode material for a battery, and in particular, using a conductive polymer substance as an electrode material,
The present invention relates to a method for manufacturing a positive electrode material for a battery, which is suitable for manufacturing a small-sized and large-capacity battery. In recent years, due to remarkable progress in microelectronics, especially semiconductor device manufacturing technology,
Highly integrated highly functional devices, represented by large scale integrated circuits (VLSI), have been realized. By adopting this in the control system of various devices, dramatic downsizing of electronic equipment has been achieved. Highly integrated and highly functional devices have contributed greatly not only to various industries but also to miniaturization and multifunctionalization of home appliances in general households.

The above-mentioned electronic equipment has a self-contained power supply device and can be operated without relying on a commercial power supply or the like, and is progressing toward so-called cordless. A battery is generally used as the power supply device. In order to reduce the size and weight of the entire electronic device and operate the device for a long time, development of high-performance batteries is required. In recent years, a battery using a conductive polymer material as a positive electrode active material has attracted attention as a material suitable for reducing the size and weight of the entire electronic device. This is because the conductive polymer substance is an organic substance, and thus has a light weight, and since it has excellent flexibility, it has excellent processability of the battery itself.

[0003]

2. Description of the Related Art Conventionally, in a battery using a conductive polymer substance as a positive electrode active material, a conductive polymer substance such as polypyrrole, polythiophene, polyacetylene or polyaniline has been used. When such a conductive polymer substance is used, as disclosed in JP-A-61-71552, a conductive polymer substance as a positive electrode active material is deposited by an electrolytic polymerization method to form a positive electrode. It is used as an electrode. In the negative electrode, an electrode is formed by using an alkali metal such as lithium or its alloy.

By connecting both electrodes with a non-aqueous electrolyte, a reduction reaction at the positive electrode, that is, a dedoping phenomenon of the dopant doped in the conductive polymer substance, progresses, and at the same time, at the negative electrode, a corresponding amount of electricity is obtained. The base substance is oxidized and diffused during electrolysis, and a voltage based on the difference in electrochemical potential between the two is output. As a method for producing a positive electrode material for a battery using such a conductive polymer substance, an electrolytic polymerization method and a casting method have been conventionally known.

According to the electrolytic polymerization method, a conductive polymer material is electrolytically polymerized in advance to form a film-like battery positive electrode material, and the film-like battery positive electrode material is assembled as an electrode. In addition, a soluble conductive polymer substance,
For example, when soluble polyaniline is used, a film is formed by a casting method, and the film is dipped in an aqueous solution of a protonic acid to perform a doping process.

[0006]

However, the conventional method for producing a positive electrode material for a battery by the electrolytic polymerization method has a problem that the efficiency of the electrolytic polymerization is low and improvement in productivity cannot be expected. That is, in the electrolytic polymerization method, the polymerization reaction proceeds only at the electrode interface of a limited area, and the reaction rate is proportional to the amount of current, so that the electrolytic polymerization rate should be kept above a certain rate in order to maintain the film quality. It was difficult to set to, and there was a limit to the manufacturing efficiency.

On the other hand, in the method of doping after forming a soluble conductive polymer by a casting method, it takes a lot of time for the dopant to diffuse into the film, and the amount of the dopant to be doped is diffused. Since there is a limitation that it is determined by the interaction between the action and the conductive polymer substance, there is a problem that a certain amount or more of doping cannot be performed and only a battery having a small amount of accumulated electricity can be manufactured.

An object of the present invention is to provide a method for producing a positive electrode material for a battery, which has a high production efficiency and can perform a large amount of doping in a short production time.

[0009]

The above-mentioned object is to cast or coat a mixed solution of a conductive polymer substance and a dopant precursor in a solvent to form a solution film, and to heat the solution film. This is achieved by the method for producing a positive electrode material for a battery, which comprises a step of removing the solvent from the solution film and drying.

In the above method for producing a positive electrode material for a battery,
The conductive polymer material is preferably polyaniline or a derivative thereof. In the method for producing a battery positive electrode material, the dopant precursor is preferably an aromatic sulfonic acid ester. In the above method for producing a battery positive electrode material, the aromatic sulfonic acid is benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, alkylnaphthalenesulfonic acid, styrenesulfonic acid, or n-dodecylbenzenesulfonic acid. Is desirable.

[0011]

According to the present invention, a mixed solution in which a conductive polymer substance and a dopant precursor are dissolved in a solvent is cast or applied to form a solution film, and the solution film is heated to remove the solution film from the solution film. Since the solvent is removed and drying is performed, a large amount of doped positive electrode material for a battery can be manufactured in a short manufacturing time.

[0012]

EXAMPLES Details of the method for producing a positive electrode material for a battery according to the present invention will be described. First, a conductive polymer polyaniline soluble in an organic solvent is obtained by adding an appropriate oxidizing agent to an aniline aqueous solution acidified with hydrochloric acid or sulfuric acid under low temperature conditions. This is dissolved in a suitable solvent, and then an aromatic sulfonic acid ester soluble in this solvent is added to form a uniform solution.

Next, this solution is applied on a suitable substrate by a casting method or the like and dried to obtain a homogeneous positive electrode active material film. When this film is heat-treated at a suitable temperature under a high humidity condition, the ester is hydrolyzed to generate an aromatic sulfonic acid. This acid is doped with polyaniline to increase the conductivity as an electrode, and at the same time,
Acts as a counter ion when operating as a battery,
It will determine the capacity of the battery.

FIG. 1 shows a specific example of a battery using the film thus manufactured. The film produced by the method of the present invention is processed and used as the positive electrode material 1, and as the negative electrode metal 3, a metal having a large reducing property, that is, a property of being easily oxidized, for example, an alkali metal, preferably lithium or A lithium / aluminum alloy is used.

A non-aqueous electrolyte 2 is sandwiched and fixed between the positive electrode material 1 and the negative electrode 3. The positive electrode substance 1, the non-aqueous electrolyte 2 and the negative electrode 3 are housed in a case 4, the positive electrode lead 5 is connected to the positive electrode substance 1, the negative electrode lead 6 is connected to the negative electrode 3, and they are projected outside the case 4. . According to the invention,
During production of an electrode active material film of a solvent-soluble conductive polymer substance, a conductive polymer is formed by mixing a substance that generates an acid in a subsequent process and becomes a dopant of the conductive polymer substance to form a film. Large amounts of dopant can be incorporated into the film without degrading the quality of the solution. Therefore, it becomes possible to form a high quality battery positive electrode active material film more efficiently and easily than the conventional electrolytic polymerization method.

Further, since it becomes possible to allow a large amount of dopant to be present in the system, rather than holding the acid serving as a dopant by diffusion after forming the positive electrode active material, the capacity of the battery is improved, and the battery is small and high in size. A battery of capacity can be constructed. Next, examples of the present invention and comparative examples will be described. Example First, a solvent-soluble polyaniline was obtained by adding the same mole number of ammonium persulfate as aniline to an aqueous 0.2M aniline solution acidic with 1N hydrochloric acid and performing chemical polymerization at -5 ° C.

Next, the polyaniline was boiled under reflux in a 1N aqueous sodium hydroxide solution, washed with pure water, and dried by heating to obtain a dedoped doping material. Next, 1 part of this polyaniline and 1 part of methyl p-toluenesulfonate were dissolved in 20 parts of N-methyl-2-pyrrolidone (NMP) to prepare a uniform solution. Next, this solution was cast on a polyester substrate, dried under reduced pressure at 80 ° C. for 1 hour, and then left under high temperature and high humidity conditions of 80 ° C. and 90% RH for 1 hour to accelerate the hydrolysis reaction of the dopant. .

The non-aqueous electrolyte (polyoxymethylene / propylene carbonate / lithium nitrate mixture) 2 is sandwiched between the positive electrode material 1 made of the positive electrode material for battery manufactured by the above treatment and the negative electrode metal 3 made of lithium, and the positive electrode material is obtained. After providing the positive electrode lead 5 and the negative electrode lead 6 on 1 and the negative electrode metal 3, the periphery was molded with the epoxy resin to form the case 4, and the battery was manufactured.

The discharge characteristics of the battery of the example manufactured as described above were measured when a constant current of 1 mA was applied and the battery was discharged. As is clear from the measurement result of FIG. 2, in the embodiment, it takes about 4 times until the voltage of 3V drops to 2V.
Needed 0 hours. (Comparative Example) A polyaniline film was prepared and then doped by immersing it in an acid solution (dopant: p-toluenesulfonic acid) for 2 to 3 hours to obtain a battery positive electrode material.

Using the battery positive electrode material thus obtained as the positive electrode substance 1, a non-aqueous electrolyte (polyoxymethylene / propylene carbonate / metal oxide) was formed between the negative electrode metal 3 made of lithium in the same manner as in Example. Lithium nitrate mixture 2 was sandwiched, positive electrode lead 5 and negative electrode lead 6 were provided on positive electrode material 1 and negative electrode metal 3, and then the periphery was molded with epoxy resin to form case 4.

The discharge characteristics of the battery of the comparative example manufactured as described above were measured when the battery was discharged by applying a constant current of 1 mA. As is clear from the measurement result of FIG. 2, in the comparative example, the initial voltage of 3V was 2V in about 18 hours.
Fell to. As described above, according to the above-described embodiment, a battery having a capacity twice as large as that of the comparative example could be manufactured in substantially the same manufacturing time.

Further, it took about 4 hours to produce a positive electrode material for a battery having the same characteristics by the electrolytic polymerization method. Therefore, according to the example described above, the manufacturing time could be shortened to 50 to 60% as compared with the electrolytic polymerization method.

[0023]

As described above, according to the present invention, a mixed solution in which a conductive polymer substance and a dopant precursor are dissolved is cast or applied to form a solution film, and the solution film is heated. As a result, the solvent is removed from the solution film and the solution film is dried. Therefore, a large amount of doped positive electrode material for a battery can be manufactured in a short manufacturing time. For this reason,
By using the positive electrode material for a battery of the present invention, a small-sized and large-capacity battery can be realized in a short manufacturing time.
Therefore, it greatly contributes to downsizing of devices using batteries, such as cordless devices.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a battery according to the present invention.

FIG. 2 is a graph showing constant current discharge characteristics of a battery of Example and a battery of Comparative Example.

[Explanation of symbols]

 1: Positive electrode material 2: Non-aqueous electrolyte 3: Negative electrode metal 4: Case 5: Positive electrode lead 6: Negative electrode lead

Claims (4)

[Claims] 1. A step of casting or coating a mixed solution of a conductive polymer substance and a dopant precursor dissolved in a solvent to form a solution film, and heating the solution film to remove the solution film from the solution film. A method for producing a positive electrode material for a battery, comprising the step of removing the solvent and drying. 2. The method for producing a positive electrode material for a battery according to claim 1, wherein the conductive polymer substance is polyaniline or a derivative thereof. 3. The method for producing a battery positive electrode material according to claim 1, wherein the dopant precursor is an aromatic sulfonic acid ester. 4. The method for producing a battery positive electrode material according to claim 3, wherein the aromatic sulfonic acid is benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, alkylnaphthalenesulfonic acid, styrenesulfonic acid, or A method for producing a positive electrode material for a battery, which is n-dodecylbenzenesulfonic acid.