JPH02288018A - Preparation of conductive composite material - Google Patents

Abstract

PURPOSE:To easily and surely obtain a composite material which effectively displays the characteristic of a conductive polymer by applying a fiber cloth to a working electrode and after electrolytic polymerization, peeling a conductive composite material to which the fiber cloth is attached off the working electrode. CONSTITUTION:SUS 316 steel is used for a working electrode, polypropylene unwoven cloth is attached closely to the electrode, a platinum plate is used as a counter electrode, and an aqueous solution containing 1mol/l aniline and 2mol/l HBF4 is used for an electrolyte. Electrolytic polymerization is carried out for 55 minutes at 20mA/cm<2> of constant current density of a working electrode and 15 deg.C of the electrolyte. Coating the unwoven cloth all over, the resulting polyaniline film is peeled off the working electrode. By this method, a composite material which effectively displays the characteristic of a conductive polymer is obtained easily and surely.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to organic conductive materials such as polyaniline, polythenylene, polypyrrole, etc., which are suitably used as battery electrode materials, photoelectric conversion collectors, electromagnetic shielding materials, color switching elements, etc. The present invention relates to a method for producing a conductive polymer composite material of a conductive polymer compound (hereinafter referred to as a conductive polymer material) and a fibrous material such as a cloth or a nonwoven fabric.

[Conventional technology]

In recent years, conductive polymer materials are being used as functional materials such as electronic materials because they are lightweight, have excellent flexibility, have good processability, and have abundant raw materials so there is no problem of resource depletion. In particular, conductive bacterial molecular materials such as polyaniline, polythenylene, polypyrrole, polyacetylene, and poly-P-phenylene are being used as electrode materials for secondary batteries and solar cells, and as color materials. It is attracting attention as an electronic material with a wide range of uses, such as switching elements, photoelectric conversion elements, electromagnetic shielding materials, and antistatic materials, and active research and development is being carried out on it.

(H, Sh irakawa, I keda, Po
ly, J. 2.2310971), Michio Sugi, Mitsuyoshi Saito et al., Applied Physics 52.567 (1983), Masayo Yokoyama, Karasu Molecule 34.728 (1985): 1. It is known that molecular compounds can be obtained by chemical oxidative polymerization or electrolytic oxidative polymerization, but conductive polymer materials produced by either method have poor processability because they are infusible and insoluble, making it difficult to use them for their intended purpose. Methods such as manufacturing by polymerizing according to the shape of the object have been adopted.

Furthermore, as mentioned above, since conductive polymer materials are brittle and difficult to process over a long period of time, they are used by being lined with SUS steel mesh or the like.

[Problem to be solved by the invention] According to the study results of the present inventor, conductive polymer materials and SU
It has been found that the potential of conventional composites integrated with S steel mesh is different during electrolytic polymerization of polymer compounds and when used for various purposes, so the material of the composite material has a large effect. Ta. In other words, as shown in the comparative example below, austenitic stainless steel such as 5US316, which is conventionally said to have excellent corrosion resistance, shows excellent corrosion resistance when electropolymerized, but it is not suitable for product applications such as batteries. 1
! When used as a pole, the potential becomes noble and it will corrode instead.

Conversely, ferritic stainless steels such as 5US444, which are resistant to corrosion at critical potentials, do not corrode when acting as battery electrodes, but corrode in concentrated acid solutions during electropolymerization.

For example, using a 5US316 stainless steel mesh as a polymerization electrode, a polyaniline film is deposited on this using an electrolytic polymerization method, a battery is created in which this polyaniline film is used as a positive electrode, and a polymerized electrode is used as a positive electrode current collector, and the cycle life is evaluated. It was discovered that the battery life was extremely short and the battery performance was extremely poor. The cause is the positive electrode current collector (SO8316)
Pitting corrosion occurs during battery testing, and the corrosion products associated with this pitting corrosion adversely affect the electrochemically active sites of polyaniline, reducing the Coulombic effect and discharge capacity of the polyaniline positive electrode. Alternatively, as corrosion progresses, peeling occurs between the polyaniline film and the current collector, resulting in a decrease in the current collection ability of the current collector and an increase in internal resistance.

As described above, the present inventors believe that when orstenitic stainless steel such as 5US316 is used for the current collector portion and polymerization electrode, corrosion during battery testing will have a serious adverse effect on battery performance such as cycle life. Found it.

In addition, when ferritic stainless steel such as 5US444 is used for the polymerization electrode, if it is left in an electrolyte containing concentrated acid for a certain period of time during electrolytic polymerization, it will corrode, the stainless steel composition metals will be eluted, and the polymerization electrolyte will This will contaminate the steel and at the same time degrade and dissolve the stainless steel reinforcement. The reason for this is that if the polymerization electrode is left in a concentrated acid solution containing fluoroboric acid or the like for more than a certain period of time, corrosion will occur because the corrosion potential of 5US444 is less noble than that of 5US316.

As a countermeasure for this, it is necessary to start electrolytic polymerization and cover it with polyaniline before the passive film that 5O8444 already has disappears, but this is extremely difficult in actual industrial production.

Furthermore, a method of electropolymerizing on a smooth metal plate and peeling off the polyaniline film is also considered, but as mentioned above, conductive polymer materials have poor flexibility, so the thickness is limited to a few 1 opm, and it is difficult to do so. If it gets too thick, it will break.

Therefore, there is a need for the development of a composite material that can effectively electrolytically polymerize a conductive polymer material such as polyaniline as described above and effectively exhibit its properties without deteriorating its molecular performance.

The present invention aims to meet the above-mentioned needs.

[Failure to solve the problem]

In order to achieve the above object, the present inventor has finally arrived at the present invention as a result of intensive research. ,
In a method for producing a conductive polymer compound by depositing and forming a conductive polymer compound on a working electrode by an electrolytic polymerization method, a fiber fabric is disposed on the working electrode in advance,
The present invention provides a method for producing a conductive composite material, in which the conductive composite material with fiber fabric is peeled from the working electrode after electrolytic polymerization.

The present invention will be explained in more detail below.

The conductive polymer material that can be produced according to the present invention is not limited in type as long as it can be obtained by electrolytic polymerization, such as polybenzene, polyvaraphenylene,
Polymers of benzene and its derivatives such as polyaniline
Mention may be made of polymers of hetero and polyaromatic compounds such as polypyridine, polythiophene, polyfuran, polypyrrole, polyanthracene and polynaphthalene.

In the present invention, when producing the above conductive polymer material by electrolytic polymerization, an electrolytic polymerization solution is placed in an electrolytic bath, and a working electrode (polymerized electrode) and a counter electrode are placed in the electrolytic bath with a predetermined gap. Electrolytic polymerization is performed by arranging the two parts apart from each other. In that case, in the present invention, the working electrode is not particularly limited as long as it is not easily corroded by the acid of the electrolytic polymerization solution, and the above-mentioned S.U.S.
Examples include 313 stainless steel, platinum, gold, lead, palladium, nickel titanium, carbon graphite, etc.

Alternatively, these materials can be deposited on film or glass,
It may be deposited by sputtering, coating, etc.

In the present invention, a fiber fabric is placed on the working electrode before electropolymerization is started.

Electrolytic polymerization is performed under predetermined conditions with a working electrode and a counter electrode separated, and the conductive polymer material is deposited on the working electrode. As the electrolytic polymerization progresses, the conductive polymer material grows to wrap and cover the disposed fiber fabric.

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

It is preferable to peel off the above-mentioned conductive composite material from the working electrode in a wet state, and the smoother the surface of the working electrode, the easier it is.

There is no particular limitation on the fiber fabric used in the present invention, but it may be sufficient as long as it allows the electrolyte to pass through it relatively easily during electrolytic polymerization and is easily in close contact with the working electrode. , woven fabrics such as twill weave, and non-woven fabrics can be used. The material of the fiber cloth used is also not particularly limited, but it may be any material that does not dissolve or deteriorate due to electrolytic polymerization and does not dissolve or deteriorate when used in products such as batteries, such as polypropylene, polyvinyl vinylide, polyethylene, Teflon, etc. etc. are preferably used.

Furthermore, the material that can be used for the counter electrode is not particularly limited as long as it is insoluble in the polymerization solution during electrolysis, in addition to the same materials as those for the above-mentioned working electrode.

When a battery is constructed using the coating material of the present invention as a battery electrode material, known materials may be used as other battery constituent members. For example, when a conductive polymer material as described above is used as a positive electrode, the negative electrode active material may be graphite or a metal that can form a mono- or divalent cation, in addition to such a conductive polymer material. lithium, sodium,
Magnesium, calcium, barium, zinc and alloys containing them (lithium-aluminum alloys) can be used.

Also, there is no problem with using commonly used electrolytes, sealing plates, battery cases, etc.

[Effect]

When manufacturing a conductive molecular material by the manufacturing method of the present invention, there are no particular restrictions on the arrangement of the working electrode and counter electrode in the electrolytic cell, but It is preferable to arrange the electrode and the counter electrode along a substantially horizontal direction, with the working electrode on the lower side and the counter electrode on the upper side, so that the gas generated from the counter electrode during electrolytic polymerization polymerizes and forms a conductive polymer on the working electrode. It has almost no effect on the membrane,
It is possible to obtain a conductive polymer that rises from the counter electrode and has a uniform film thickness on the working electrode without pinholes or cracks. Furthermore, in this case, in order to prevent the gas generated under the counter electrode from partially condensing and stagnation, if the counter electrode is made into a net shape or other shape that allows gas to easily pass through, a more uniform film can be obtained on the working electrode. I can do it. Similarly, applying vibration to the opposite electrode is effective for gases.

However, it is possible to form the above-mentioned working electrode into a long sheet and perform electrolytic polymerization while running the working electrode continuously or intermittently, thereby making it possible to continuously mass-produce conductive polymer membranes. can do.

The composition and electrolytic conditions of the electrolytic polymerization solution used in the present invention can be conventional compositions and conditions, and may be appropriately selected depending on the type, film thickness, physical properties, etc. of the conductive polymer to be produced.

Particularly, the electrolytic polymerization conditions are as follows: (a) The temperature of the electrolytic polymerization solution is set to -40°C to 30°C, preferably -5°C to 20°C.

(b) The current density of the electrode (working electrode) on the side where the conductive polymer film is deposited is 50 A/c+yf or less.

(c) Do not stir the electrolytic polymerization solution, which may cause the generation or increase of polymer suspended matter.

It is desirable to adopt

〔Effect of the invention〕

The effects of the present invention are as follows.

The present invention is a method for producing conductive bacterial molecular material by electrolytic polymerization method by immersing a working electrode and a counter electrode in electrolytic polymerization conditions housed in an electrolytic cell. By the manufacturing method of polymerizing and then peeling off the conductive composite material with the working electrode fiber cloth, (1) it is possible to easily and reliably obtain a composite material that can effectively exhibit the properties of the conductive polymer material. .

(11) When a battery was constructed using the four-electrode cylindrical molecular material produced as described above as a battery positive electrode, and a cycle test was conducted, the results were as follows: Very good cycle life is obtained. 5US4 also causes corrosion during electrolytic polymerization.
Since there is no need to use 44 stainless steel, the electrolyte is kept pure and there is no inconvenience during work.

(iiD) Due to the presence of fiber fabric as the core material, battery work could be carried out successfully without any problems such as cracking during battery production.

qVJ The conductive composite material of the present invention has high corrosion resistance both in electrolytic polymerization and in product tests such as batteries, and at the same time effectively exhibits the characteristics of conductive polymers, it also has excellent performance in terms of processability, strength, etc., as well as price. It can be said that it is an excellent product in this respect as well.

(■) The conductive composite material in which the fiber fabric and polymer material of the present invention are integrated can be used for electrode materials such as secondary batteries and solar cells, photoelectric conversion elements, electromagnetic wave sealing materials, color switching elements, etc. When the composite material produced according to the present invention is used as an electrode for 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 the @ or pole of a battery, fiber cloth or nonwoven fabric is used as a reinforcing material, and 5US444 causes corrosion during electrolytic polymerization and pitting corrosion occurs when the battery is used. Since 5US316 is not used, electrolytic polymerization can be carried out well, and there are also advantages in terms of battery performance, such as a long cycle life.

〔Example〕

Examples of the present invention are shown below, but the present invention is not limited only to the examples.

Example 1 Stainless steel with the following composition was used for the working electrode, a polypropylene nonwoven fabric (thickness 10 μm) was adhered to the working electrode, a platinum plate was used for the counter electrode, and 1 mol/l of aniline, 2 An aqueous solution containing mol/l HBF4 was used.

The electrolytic conditions were a liquid temperature of 15°C and a working electrode current density of 20 nL.
When electrolytic oxidation polymerization was carried out for 55 minutes at a constant current of A/αi, a polyaniline film was obtained in the form of completely covering the nonwoven fabric. The polyaniline composited with this nonwoven fabric is carefully peeled off from the working electrode. The working electrode surface after peeling was free of corrosion and had a mirror surface.

Stainless steel composition (SUS 316) CO, 03% Si O, 15 Mn 0.04 p 0.015 So, 015 Ni O, 18 Cr30. O MO2,0 Other components are Fe Next, polyaniline composite material is used as the battery positive electrode, and AI is used as the negative electrode!
-Li alloy was used, and a non-aqueous electrolyte in which 1 M LiBF4 was dissolved in a mixed solvent of polypyrene carbonate and demethoxyethane was used.

This battery was subjected to a cycle life test in which it was repeatedly charged and discharged under 4-cycle drying conditions at 60°C.

The conditions for charging and discharging were to charge with a constant current of 0.6 mA until the battery voltage reached 3.3 V, and then discharge with a constant current of 0.67 Q until the battery voltage reached 2.0 ■. The cycle life of the battery was defined as the number of cycles at which the discharge capacity of the battery became 50% or less of the initial value after repeated charging and discharging.

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

Comparative Example 1 Example 1 except that a stainless steel mesh with the same composition as in Example 1 was used for the working electrode, and it was not closely covered with nonwoven fabric.
Aniline was electrolytically polymerized in the same manner as described above, and a polyaniline film was deposited on the working electrode surface to obtain a composite material in which the working electrode and the polyaniline film were integrated.

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

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

Corrosion products accompanying this pitting corrosion adversely affect the electrochemically active sites of polyaniline and cause separation between the polyaniline film and the current collector, resulting in a reduction in cycle life.

Comparative Example 2 The same electrolytic solution composition and solution temperature as in Example 1 were used, except that a stainless steel mesh having the composition shown below was used as the working electrode, and the working electrode was not closely covered with a nonwoven fabric. In this state, it was left for 2 hours without performing electrolytic polymerization. The electrolyte gradually turned brown and became opaque.

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

Composition of stainless steel (’　　　0.025* Si1. O Mn 1.0 p 0104 SO,03 (::r20.O Mo　　　2.5 Ni O,025 'l'i 0.8 Others are Fe

Claims (1)

[Claims] 1. A working electrode and a counter electrode are immersed in an electrolytic polymerization solution contained in an electrolytic cell, and a conductive polymer compound is deposited on the working electrode using an electrolytic polymerization method. In the method for producing a conductive composite material, a fiber cloth is placed on the working electrode in advance, and after electrolytic polymerization, the conductive composite material with the fiber cloth is peeled off from the working electrode. Manufacturing method. 2. The method for producing a conductive composite material according to claim 1,
A method for producing a conductive composite material in which the fiber fabric is a nonwoven fabric. 3. The method for producing a conductive composite material according to claim 2,
A method for manufacturing a conductive composite material in which the nonwoven material is polypropylene. 4. The method for producing a conductive composite material according to claim 1 or 2, wherein the material of the conductive polymer compound is polyaniline.