JPH0779007B2 - Manufacturing method of conductive composite material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to organic conductive materials such as polyaniline, polythienylene, polypyrrole, which are preferably used as battery electrode materials, photoelectric conversion elements, electromagnetic wave shielding materials, color switching elements and the like. The present invention relates to a method for producing a conductive polymer composite material of a conductive polymer substitute (hereinafter simply referred to as a conductive polymer material) and a fibrous material such as cloth or nonwoven fabric.

[Conventional technology]

In recent years, conductive polymer materials have been used as functional materials such as electronic materials because of their light weight, excellent flexibility, good workability, and the abundance of raw materials that do not cause resource exhaustion. Conductive research and development have been actively carried out, and among them, conductive polymer materials such as polyaniline, polythienylene, polypyrrole, polyacetylene, and poly-P-phenylene are used as electrode materials for secondary batteries and solar cells. It has attracted attention as an electronic material having a wide range of applications such as a color switching element, a photoelectric conversion element, an electromagnetic wave shielding material, and an antistatic material, and vigorous research and development has been conducted. [H. Shirakawa, Ikeda, Poly.J.2.231 (1971),
Sugi Michio, Saito Mitsuyoshi et al., Applied Physics 52.567 (1983), Yokoyama Masaaki, Polymer 34.728 (1985)] Conventionally, conductive polymer compounds such as those mentioned above have been prepared by chemical oxidative polymerization or electrolytic oxidative polymerization. It is known to be obtained, but the conductive polymer material produced by either method is infusible and insoluble, so that it is inferior in processability, and is produced by polymerizing in accordance with the shape of the intended use. Etc. are adopted.

Further, as described above, since the conductive polymer material is brittle and difficult to be secondary processed, it is used by being lined with a net made of SUS steel or the like.

[Problems to be Solved by the Invention]

According to the examination result of the present inventor, conductive polymer material and SUS
It has been found that the potential of the composite material in a conventional composite material that integrates a steel net has a great influence during electropolymerization of polymer compounds and when it is used for various purposes. . That is, as shown in Comparative Examples below, austenitic stainless steel such as SUS316, which is conventionally said to be excellent in corrosion resistance, shows excellent corrosion resistance during electrolytic polymerization, but is used for products such as batteries. When used as an electrode, it becomes corrosive because it has a noble potential.

On the other hand, ferritic stainless steels such as SUS444, which have excellent corrosion resistance at noble potential, do not corrode when acting as a battery electrode, but corrode with a concentrated acid solution during electrolytic polymerization.

For example, a net of SUS316 stainless steel is used as a polymerization electrode, and a polyaniline film is deposited and formed on this by an electrolytic polymerization method, and a battery using the polyaniline film as a positive electrode and the polymerization electrode as a positive electrode current collector is prepared, and the cycle life is increased. Upon evaluation, it was found that the battery life was extremely short and the battery performance was extremely poor. The cause is that pitting corrosion occurs on the positive electrode current collector (SUS316) during the battery test, and the corrosion product accompanying this pitting corrosion adversely affects the electrochemically active site of polyaniline, and the polyaniline positive electrode Coulomb effect. Or to reduce the discharge capacity, or to cause peeling between the polyaniline film and the current collector with the progress of corrosion, which causes a decrease in the current collecting ability of the current collector and an increase in internal resistance. is there.

In this way, when an austenitic stainless steel such as SUS316 is used for the current collector, that is, the polymerized electrode, the present inventor may have a serious adverse effect on the battery performance such as cycle life due to corrosion during the battery test. Was found by.

Further, when a ferrite type stainless steel such as SUS444 is used for the above-mentioned polymerization electrode, it is corroded when left in an electrolytic solution containing concentrated acid for a certain time or more during electrolytic polymerization, the stainless steel composition metal is eluted, and the polymerization electrolytic solution At the same time, it will deteriorate and dissolve the stainless steel reinforcing material. This is because the corrosion potential of SUS444 is SUS3 when it is left in a concentrated acid solution containing borofluoric acid, etc.
Corrosion occurs because it is baser than that of 16.

As a countermeasure against this, it is necessary to start electrolytic polymerization before the passivation film already possessed by SUS444 and cover it with polyaniline, which is extremely difficult in actual industrial production.

A method of stripping the polyaniline coating by electrolytic polymerization on a smooth metal plate is also conceivable. However, since the conductive polymer material is inferior in flexibility as described above, the thickness is limited to several tens of μm, and the thickness is further increased. Then it will break.

Therefore, there has been a demand for the development of a composite material which effectively electrolytically polymerizes a conductive polymer material such as polyaniline as described above and effectively exhibits its characteristics without deteriorating the performance as a polymer. The present invention aims to meet the above-mentioned needs.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present inventor has conducted earnest research and, as a result, finally reached the present invention.The present invention involves immersing a working electrode and a counter electrode in an electropolymerization solution contained in an electrolytic cell. ,
By depositing and forming a conductive polymer compound on the working electrode by an electrolytic polymerization method, in a method for producing a conductive polymer compound, the working electrode and the counter electrode in the electrolytic polymerization liquid of the electrolytic cell in a substantially horizontal direction. Then, the working electrode is arranged on the lower side and the counter electrode is arranged on the upper side, and the fiber cloth is previously arranged on the working electrode,
The present invention provides a method for producing a conductive composite material in which the conductive composite material with a fiber cloth is peeled off from the working electrode after electrolytic polymerization.

The present invention will be described in more detail below.

The conductive polymer material that can be produced according to the present invention is not limited in kind as long as it can be obtained by electrolytic polymerization, and examples thereof include polybenzene and polyparaphenylene.
Polymers of benzene and its derivatives, such as polyaniline,
Examples include polymers of hetero- and polynuclear aromatic compounds such as polypyridine, polythiophene, polyfuran, polypyrrole, polyanthracene and polynaphthalene.

In the present invention, when the above-mentioned conductive polymer material is produced by an electrolytic polymerization method, an electrolytic polymerization solution is put into an electrolytic cell, and a predetermined working electrode (polymerization electrode) and counter electrode are put in the electrolytic cell. Electropolymerization is performed by arranging them at intervals. In that case, in the present invention, the working electrode is not particularly limited as long as it is difficult to be corroded by the acid of the electrolytic polymerization solution, and the above-mentioned SUS313 stainless steel, platinum, gold, lead, palladium, nickel, titanium, carbon graphite, etc. Is mentioned. Alternatively, these materials may be deposited on a film or glass by vapor deposition, sputtering, coating or the like.

In the present invention, the fiber cloth is arranged on the working electrode before the electrolytic polymerization is started.

The electropolymerization is performed between the working electrode and the counter electrode under certain conditions, but the conductive polymer material is deposited on the working electrode. As the electrolytic polymerization progresses, the conductive polymer material grows so as to cover and cover the arranged fiber cloth.

After predetermined conditions, the polymerization is stopped, and the conductive composite material is peeled off from the working electrode using the fiber cloth as the core material.

The above-mentioned conductive composite material is preferably peeled off from the working electrode in a wet state, and the smoother the working electrode surface, the easier the peeling.

The fiber cloth used in the present invention is not particularly limited, as long as it allows the electrolytic solution to pass relatively easily during the electropolymerization and easily adheres to the working electrode, a plain weave of various cloths, a blind weave, A woven fabric such as a twill or a non-woven fabric can be used. Further, the material of the fiber cloth used is not particularly limited, but it does not dissolve or deteriorate due to electrolytic polymerization, and even when used in products such as batteries, it does not have to dissolve and deteriorate, and polypropylene, polyvinyl chloride, polyethylene, Polyester or the like is preferably used.

The material that can be used for the counter electrode may be the same as the material for the working electrode described above, and is not particularly limited as long as it is insoluble in the polymerization liquid during electrolysis.

When a battery is constructed by using the composite material of the present invention as a battery electrode material, other known battery constituent members can be used. For example, when the above-mentioned conductive polymer material is used as the positive electrode, as the negative electrode active material, in addition to such conductive polymer material, a graphite or a metal capable of becoming a mono- or divalent cation, such as lithium , Sodium, magnesium, calcium, barium, zinc and alloys containing them (lithium-aluminum alloys) can be used.

In addition, there is no problem in using electrolytes, sealing plates, battery cases, etc. that are normally used.

[Action]

When producing a conductive polymer material by the production method of the present invention, there is no particular limitation on the arrangement of the working electrode and the counter electrode disposed in the electrolytic cell, but the working electrode and the counter electrode in the electrolytic polymerization liquid of the electrolytic cell. And in a substantially horizontal direction, and the working electrode on the lower side,
It is preferable to arrange the counter electrode on the upper side, whereby the gas generated from the counter electrode during electrolytic polymerization hardly affects the conductive polymer film polymerized and formed on the working electrode and rises from the counter electrode. The effect that a uniform conductive polymer having a uniform film thickness without pinholes or cracks on the working electrode can be obtained. Furthermore, in this case, in order to prevent the gas generated below the counter electrode from partially condensing and stagnating, if the counter electrode is formed in a mesh shape or other shape that allows easy gas passage, a more uniform film can be obtained on the working electrode. You can Similarly, applying vibration to the counter electrode is effective in separating gas.

Further, the working electrode can be formed in a long sheet shape, and electrolytic polymerization can be carried out while running the working electrode continuously or intermittently, whereby a conductive polymer film is continuously mass-produced. be able to.

The composition and electrolysis conditions of the electropolymerization solution used in the present invention may be the conventional compositions and conditions, and may be appropriately selected according to the type, film thickness and physical properties of the conductive polymer to be produced.

(A) The temperature of the electropolymerization liquid is -40 ° C to 30 ° C, preferably -5.
Set to ℃ ~ 20 ℃.

(B) The current density of the electrode (working electrode) on the side where the conductive polymer film is deposited is set to 50 A / cm ² or less.

(C) Do not stir the electropolymerization liquid, which may cause generation or increase of polymer suspended matter.

It is desirable to adopt.

〔The invention's effect〕

The effects of the present invention are summarized as follows. The present invention is a method of immersing a working electrode and a counter electrode in an electrolytic polymerization solution housed in an electrolytic cell, and producing a conductive polymer material by an electrolytic polymerization method, in which a fiber cloth is disposed on the working electrode in advance. Then, by the manufacturing method in which the conductive composite material with the fiber cloth is peeled off from the working electrode after the electrolytic polymerization, (i) the composite material capable of effectively exhibiting the characteristics of the conductive polymer material is simple and reliable. Can be obtained.

(Ii) When a battery is constructed using the conductive polymer material produced as described above as a battery positive electrode and a cycle test is performed, there is no material that causes pitting corrosion such as SUS316 stainless steel, so it is extremely good. Cycle life is obtained. In addition, since it is not necessary to use SUS444 stainless steel which causes corrosion even in electrolytic polymerization, the electrolytic solution is kept pure and there is no inconvenience in work.

(Iii) Since the fiber cloth is present as the core material, the battery work was satisfactorily carried out without causing any inconvenience such as cracking when the battery was produced.

(Iv) The conductive composite material of the present invention has high corrosion resistance both in electrolytic polymerization and in product tests of batteries and the like, and effectively exhibits the characteristics of the conductive polymer, and at the same time, in terms of performance such as workability and strength, It can be said that it is an excellent product in terms of price.

(V) The conductive composite material in which the fiber cloth of the present invention and a polymer material are integrated is used for an electrode material of a secondary battery or a solar cell, a photoelectric conversion element, an electromagnetic wave sealing material, a color switching element, or the like. Therefore, when the composite material manufactured according to the present invention is used as an electrode of a battery, the conductive composite material effectively functions as a positive electrode and / or a negative electrode. In this way, when the composite material of the present invention is used as a battery electrode, a fiber cloth or a non-woven fabric is used as a reinforcing material, and SUS444 that causes corrosion in electrolytic polymerization or SUS316 that causes pitting corrosion when using a battery is used. Since it is not used, it has advantages such that good electrolytic polymerization can be carried out and the cycle life is long in battery performance.

(Vi) Generated from the counter electrode during electropolymerization by arranging the working electrode and the counter electrode in the electropolymerization solution in the electrolytic cell in a substantially horizontal direction, and disposing the working electrode on the lower side and the counter electrode on the upper side. The gas has almost no effect on the conductive polymer film formed by polymerization on the working electrode and rises from the counter electrode to obtain a uniform conductive polymer having a film thickness on the working electrode without pinholes or cracks. it can.

〔Example〕

Examples of the present invention will be shown below, but the present invention is not limited to the examples.

Example 1 A stainless steel having the following composition was used as a working electrode, a polypropylene non-woven fabric (thickness 10 μm) was closely placed on the working electrode, a platinum plate was used as a counter electrode, and 1 mol / l of aniline was used as an electrolytic solution. An aqueous solution containing mol / l HBF ₄ was used.

As electrolysis conditions, electrolytic oxidative polymerization was carried out for 55 minutes at a constant temperature of a working electrode current density of 20 mA / cm ² at a liquid temperature of 15 ° C., and a polyaniline coating was obtained in a form in which the nonwoven fabric was completely covered. The polyaniline composited by this non-woven fabric is carefully peeled off from the working electrode. The surface of the working electrode after peeling was not corroded and showed a mirror surface.

Stainless steel composition (SUS316) C 0.03% Si 0.15 Mn 0.04 P 0.015 S 0.015 Ni 0.18 Cr 30.0 Mo 2.0 Other components are Fe Next, polyaniline composite material is used for battery positive electrode and negative electrode is Al-Li.
An alloy was used, and as the electrolyte, a non-aqueous electrolyte in which iMLiBF ₄ was dissolved in a mixed solvent of polypropylene carbonate and dimethoxyethane was used.

This battery was subjected to a cycle life test in which charging and discharging were repeated under a constant temperature condition of 60 ° C. Charge / discharge is 0.6mA
The battery is charged at a constant current of 3.3V until the battery voltage becomes 3.3V, and then discharged at a constant current of 0.6mA until the battery voltage becomes 2.0V. The cycle number of the battery was defined as the number of cycles when the discharge capacity reached 50% or less of the initial value.

As a result of the experiment, the cycle life in the present invention was 189 times, and it was confirmed that the composite in which the polyaniline and the nonwoven fabric were integrated had excellent characteristics as a battery electrode.

Comparative Example 1 Electrolytic polymerization of aniline was carried out in the same manner as in Example 1 except that a stainless steel net having the same composition as in Example 1 was used as the working electrode, and the non-woven fabric was not used for adhesion coating, and polyaniline was applied to the working electrode surface. A film was deposited and formed to obtain a composite material in which the working electrode and the polyaniline film were integrated.

Next, using the polyaniline film as the battery electrode and the working electrode as it was as the positive electrode current collector, a battery similar to that of Example 1 was prepared, and its cycle life was measured. The result was 89 times.

After the end of the test, the battery of Comparative Example 1 was disassembled and the positive electrode current collector was observed by an electron microscope. As a result of the research conducted by the present inventors, it was confirmed that pitting corrosion occurred in the stainless steel.

Corrosion products resulting from the occurrence of pitting corrosion adversely affect the electrochemically active sites of polyaniline and cause peeling between the polyaniline film and the current collector, thus shortening the cycle life.

Comparative Example 2 The same electrolytic solution composition and liquid temperature as in Example 1 were used, except that a stainless steel net having the following composition was used for the working electrode, and the working electrode was not covered with a non-woven fabric. In this state, electrolytic polymerization was not carried out and the mixture was left for 2 hours. The electrolyte gradually became dark brown and became opaque.

Further, when the working electrode after immersion was taken out and observed with an electron microscope, it was confirmed that pitting corrosion had occurred on the stainless steel surface. It was confirmed that the corrosion product accompanying the occurrence of pitting corrosion was a brownish substance.

Composition of stainless steel C 0.025% Si 1.0 Mn 1.0 P 0.04 S 0.03 Cr 20.0 Mo 2.5 Ni 0.025 Ti 0.8 Others are Fe

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Claims (4)

[Claims] 1. A conductive polymer is prepared by immersing a working electrode and a counter electrode in an electrolytic polymerization solution contained in an electrolytic cell and depositing a conductive polymer compound on the working electrode by an electrolytic polymerization method. In the method for producing a compound, a working electrode and a counter electrode are arranged in a substantially horizontal direction in an electrolytic polymerization solution in an electrolytic cell, and the working electrode is disposed on the lower side and the counter electrode is disposed on the upper side, and the working electrode is preliminarily made of a fiber cloth. Is provided, electrolytic polymerization is performed, and then the conductive composite material with the fiber cloth is peeled off from the working electrode. 2. The method for producing a conductive composite material according to claim 1, wherein the fiber cloth is a non-woven fabric. 3. The method for producing a conductive composite material according to claim 2, wherein the material of the non-woven fabric is polypropylene. 4. The method for producing a conductive polymer composite material according to claim 1, wherein the material of the conductive polymer compound is polyaniline.