JP3038775B2 - Electropolymerization method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrolytic polymerization method for imparting a new function to a conductive polymer, and particularly to a method for forming a battery electrode incorporating active material particles. The present invention relates to a method for manufacturing a battery electrode.

[Conventional technology]

Conductive polymers are expected to be used in a variety of applications due to their unique properties. For example, attempts have been made to use functional particles as dopant anions (or a part thereof) to add new functions to conductive polymers. It has been done.

For example, in a lecture (1E17) at the Electrochemical Conference held in April 1999, it was found that particles such as tungsten oxide (WO ₃ ) dispersed in a polymerization solution could be incorporated into polypyrrole. It has been reported that polypyrrole can be imparted with a function such as electrochromism.

FIG. 2 illustrates an electropolymerization method for incorporating tungsten oxide (WO ₃ ) into polypyrrole.
In this method, a positive electrode (104) and a negative electrode (105) are vertically opposed to each other in an electrolytic tank (103) filled with an electropolymerization solution (102) in which tungsten oxide particles (101) are dispersed, and these positive electrodes ( A DC power supply (106) is placed between the negative electrode (104) and the negative electrode (105) to conduct electropolymerization, and the tungsten oxide particles (101) are electrophoretically transferred to the positive electrode (104) or the negative electrode (105). Polypyrrole is electrolytically polymerized at the same time as it is drawn. Therefore, in the obtained polypyrrole film, tungsten oxide particles are taken in, and the function of tungsten oxide is given to polypyrrole, which is a conductive polymer.

[Problems to be solved by the invention]

By the way, as described above, in the method in which the positive electrode and the negative electrode are vertically opposed to each other and electrolytically polymerized, functional particles having poor dispersibility are applied because the particles are taken in during polymerization using the electrophoretic properties of the particles. It is difficult to perform the method, and even if it has an affinity for a conductive polymer, it cannot be applied to particles without electrophoresis. Therefore, the types of applicable functional particles are limited, and it is difficult to cope with various uses.

Further, in the above-described method, the functional particles are attracted to the electrode against the gravity, and the amount of the functional particles that can be captured is naturally limited, so that a large amount of the functional particles cannot be captured.

Therefore, the present invention has been proposed in view of such a conventional situation, and has an object to enable incorporation of active material particles into a conductive polymer and enable application to battery electrode production. .

Still another object of the present invention is to provide a method for producing a battery electrode which can freely set the composition ratio between an electropolymerized conductive polymer and active material particles and can incorporate a large amount of active material particles. And

[Means for solving the problem]

The present invention is characterized in that, in order to achieve the above-described object, an electrolytic electrode is horizontally arranged in an electrolytic polymerization solution containing active material particles, and electrolytic polymerization is performed by supplying a current to the electrolytic electrode. .

That is, the present invention provides all functions by placing an electrolytic electrode horizontally in an electrolytic polymer solution and performing electropolymerization while depositing functional particles on the electrolytic electrode using gravity as well as electrophoresis. It enables the incorporation of sex particles.

The electrolytic electrode is usually composed of a pair of positive and negative electrodes, but may be arranged so that both the positive electrode and the negative electrode are horizontal, or only one of the electrodes is horizontal. It may be arranged. In short, it is only necessary that the electrolytic electrode on the side where the conductive polymer is polymerized is horizontally arranged in the electrolytic polymerization solution. Note that a slight inclination is allowed even if it is horizontal.

Electrolytic polymerization, as described above, after placing the electrode on the side where the conductive polymer is polymerized among the electrolytic electrodes horizontally near the bottom of the polymerization liquid, the functional particles are dispersed or settled in the electrolytic polymerization liquid, Alternatively, it is performed while settling. When the functional particles float, the electrode on the side where the conductive polymer is polymerized is placed in horizontal contact with the surface of the polymerization liquid. As a result, functional particles of all types, such as functional particles having poor dispersibility, functional particles having an affinity for a conductive polymer but having no electrophoretic properties, and functional particles having an extremely small particle size, can be obtained. It is taken into a conductive polymer (electrolytic polymerized film) to be electrolytically polymerized.

 The functional particles are the active material of the battery in the present invention.

On the other hand, the electrolytic polymerization solution contains a solvent or a monomer or oligomer which is a structural unit of a conductive polymer, and further contains an electrolyte or the like as necessary. Any of these solvents, monomers, oligomers, and electrolytes used in ordinary electrolytic polymerization can be used.

The conductive polymer to be electrolytically polymerized is not limited at all, and examples thereof include polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyazulene, polypyridine, triphenylamine and derivatives thereof.

[Action]

When an electrolytic electrode is disposed horizontally in an electrolytic polymerization solution containing functional particles and polymerization is performed, the functional particles are attracted to the electrode by gravity or buoyancy. Therefore, for example, performance particles having poor dispersibility, functional particles having no force toward the electrode, or even functional particles that are extremely small and float, are deposited on the electrolytic electrode surface, and are subjected to electrolytic polymerization. Incorporated in conductive polymers.

In addition, the rate of incorporation of the functional particles into the conductive polymer is largely governed by the rate of sedimentation of the particles. In other words, fine particles and functional particles having good dispersibility have a low take-in speed. On the other hand, the generation rate of the conductive polymer depends on the current value.

Therefore, the composition of the conductive polymer and the functional particles is controlled by appropriately combining the sedimentation velocity of the functional particles and the current value applied to the electrolytic electrode.

〔Example〕

 Hereinafter, the present invention will be described based on specific examples.

Example 1 The configuration of the electrolytic polymerization cell used in this example is as shown in FIG.

In this electrolytic polymerization cell, a disc-shaped platinum plate (2) is arranged at the bottom of a cylindrical glass tube (1) having a flange portion (1a) at one end, and the platinum plate (2) is used to form the glass tube. (1)
The bottom is sealed. The inner diameter of the glass tube (1) is 16 mm in this example. The platinum plate (2) and the glass tube (1) are connected to the flange portion (1) of the glass tube (1).
a) A pair of holding fittings (5) and (6) are screwed together via a disc-shaped polytetrafluoroethylene plate (3) and an O-ring (4) having substantially the same diameter. Thus, the hermetically sealed state is ensured.

In the glass tube (1), an electrolytic polymerization solution (7)
And a disk-shaped stainless steel plate (8) is horizontally arranged near the liquid surface so as to face the platinum plate (2) at the bottom of the glass tube (1). When this electrolytic polymerization cell is installed, it goes without saying that the platinum plate (2) is arranged horizontally.

A DC power supply (9) is connected to the platinum plate (2) and the stainless steel plate (8) to form an electrolytic polymerization cell using the platinum plate (2) as a positive electrode and the stainless steel plate (8) as a negative electrode. .

Using the electrolytic polymerization cell having the above-described configuration, an attempt was made to form an electrode for a battery in which the active material was functional particles.

First, lithium perchlorate as an electrolyte was added in an amount of 0.2 mol /
Of pyrrole was added at a ratio of 0.2 mol / to a propylene carbonate solution containing the same at a ratio of 1 and dispersed to prepare an electrolytic polymerization solution. Next, this electrolytic polymerization solution was injected into the glass tube (1) of the electrolytic polymerization cell.

Among them, LiCoO ₂ powder (particle size 38 μm) as functional particles
The following) was added and stirred lightly. This allows LiCoO ₂
The powder was appropriately dispersed and settled on a platinum plate (2).

Immediately thereafter, a stainless steel plate (8) having a diameter of 16 mm was immersed from above, and a polypyrrole film was electrolytically polymerized on the platinum plate (2) as a positive electrode, using the platinum plate (2) as a positive electrode and the stainless steel plate (8) as a negative electrode. did. The amount of polymerization electricity was 10 clones.

The polypyrrole-LiCoO ₂ composite film formed on the platinum plate (2) contains LiCoO ₂ powder almost as charged.
In addition, they had autonomy.

This composite membrane was washed and dried at 80 ° C. in an argon stream to form electrodes, and a coin-type battery was prototyped. For the counter electrode, a lithium metal plate punched to a diameter of 15.5 mm was used. For the electrolyte, a mixture of propylene carbonate and 1,2-dimethoxyethane in a ratio of 1: 1 (by volume) and LiClO ₄ at a ratio of 1 mol / l was used. The dissolved one was used. A polypropylene porous membrane was used for the separator.

After charging this coin type battery to 4.0V for 2 hours, at 1mA
The battery was discharged to 2.5 V, and the capacity was measured. As a result, the discharge capacity was 4.1 mAH.

Comparative Example 1 50 ml of the same electrolytic polymerization solution as in Example 1 was placed in a beaker cell, and 200 mg of LiCoO ₂ powder was suspended. Then, as shown in FIG. 2, two platinum electrodes having a diameter of 16 mm were vertically arranged therein, and electrolytic polymerization was performed. The amount of polymerization electricity is 10 clawlon as in Example 1.

As a result, a polypyrrole film having LiCoO ₂ powder sparsely attached on the positive electrode side platinum electrode was obtained.

Using this polypyrrole film as an electrode, a battery similar to that of Example 1 was trial-produced and its capacity was measured. As a result, it was 0.32 mAH.
The capacity is significantly smaller than that of the battery experimentally manufactured in Example 1. This is considered to be due to the fact that the polypyrrole film contains almost no LiCoO ₂ powder as an active material.

Example 2 First, an electrolytic polymerization solution prepared by dissolving tetrabutylammonium hexafluorophosphate as an electrolyte in nitrobenzene at a ratio of 0.1 mol / and benzene as a monomer in 1 monomer / was prepared. Poured into the polymerization cell.

Pitch coke powder (particle size)
33 mg of 38 μm or less), a stainless steel plate (8) with a diameter of 16 mm is immersed from above, and a polyparaphenylene film is formed on a platinum plate (2) as a positive electrode with the platinum plate (2) as a positive electrode and the stainless steel plate (8) as a negative electrode. Was electrolytically polymerized. The amount of polymerization electricity is also here
There were 10 clones.

The polyparaphenylene-pitch coke composite membrane thus obtained was washed and dried at 30 ° C. in an argon stream to obtain a working electrode. Then, a test cell was made as a counter electrode of lithium, and a constant current was passed between 0V and 2V.
9mAH power supply was possible.

Therefore, this composite film can be used, for example, as a negative electrode of a lithium secondary battery.

Comparative Example 2 Pitch coke powder was dispersed and electropolymerized in the same manner as in Comparative Example 1 using the same electrolytic polymerization solution as in Example 2.

However, in this case, no incorporation of the pitch coke powder into the polyparaphenylene film was observed, and the amount of electricity that could be passed on the test cell of the film polymerized with the same amount of electricity as in Example 2 was 0.18 mAH. .

〔The invention's effect〕

As is clear from the above description, in the present invention, since the electrolytic polymerization is performed by horizontally arranging the electrolytic electrodes, it is possible to incorporate all kinds of functional particles into the conductive polymer. is there.

In addition, since the functional particles can be incorporated in a large amount into the conductive polymer, it is possible to impart excellent functionality to the conductive polymer.

Furthermore, in the present invention, two or more types of functional particles can be incorporated, the composition of the functional particles can be freely changed, and it is possible to cope with various uses by combining functions.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a configuration of an electrolytic polymerization cell used in Examples. FIG. 2 is a sectional view schematically showing a conventional electrolytic polymerization method. 2 ... Platinum plate (electrolytic electrode) 7 ... Electropolymerization liquid

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mio Nishi 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (56) References JP-A-62-181329 (JP, A) JP-A Sho JP-A-62-181325 (JP, A) JP-A-63-308032 (JP, A) JP-A-63-230706 (JP, A) JP-A-63-268730 (JP, A) A) JP-A-62-250005 (JP, A) JP-A-62-279229 (JP, A) JP-A-60-137923 (JP, A) JP-A-59-23889 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) C08G 61 / 12,73 / 00

Claims (1)

(57) [Claims] 1. A method for manufacturing a battery electrode, comprising: placing an electrolytic electrode horizontally in an electrolytic polymerization solution containing active material particles;