JPS61133557A - Battery having polymer electrode and making thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application: The present invention has at least one electrode, the active material of which is composed of a conductive organic polymer compound of polyconjugated structure, which can be doped with cations or anions, and which has at least one electrode. relates to a battery comprising an aluminum derivative.

Prior art: When electrically conductive organic polymers are synthesized from the corresponding monomers, the final product is obtained either as a crystalline powder, more or less deeply colored, depending on the conditions of development, or as a sheet covering the walls of the reaction vessel in a film-like manner. . This product is then separated from the liquid reaction medium, typically a suspension of a Ziegler-Natsuta catalyst in an organic solvent, and is easily shaped and processed after purification.
' can be managed.

To date, for use as electrode material in polymer batteries, for example (OH) It was common to improve. Since the connection with the metal conductor is carried out only by mechanical pressure, this current conduction is unsatisfactory even in the case of planarly formed conductor materials due to the unavoidable contact resistance, which lowers the potential of the loaded electrode.

For this reason, means have recently been developed for chemically or physicochemically bonding polymeric materials to metal derivatives with advantageously low contact resistance.

Such measures include, for example, depositing strips of metal conductors on the membranous polymer structure, by sputtering, or by photographically producing electrically conductive layers on the polymer surface. In this case, however, it must be taken into account that the volumetric change of the polymer during charging and discharging cycles can cause rupture of the deposited or printed derivative film.

Many conductive polymers are generated from monomers by oxidation, in which primary radical ions are formed, which dimerize and are further oxidized to polymer chains via oligomer intermediate units with the addition of other monomers.

It is known from DE 53 26 19 to carry out such a synthesis of polymers directly on a porous metal molding as a substrate for polymer deposition and regrowth. The metal shaped body therefore simultaneously becomes the supporting framework and derivative of the organic electrode material that undergoes the subsequent doping (and thus enters the active state). Considering that many polymers are characterized by very high oxidation potentials A relatively corrosion-resistant metal such as nickel, nickel-chromium, copper-nickel, silver or platinum is used.

On the contrary, according to JP-A-59-12576 (West German Patent Publication No. 3624 968), aluminum is vacuum-deposited on both sides of a sheet-like polyacetylene material, and metal coating 1 is applied.
The recovered polymer is subsequently subjected to a recoil-ion implantation treatment, during which the aluminum atoms penetrate into the conductive polymer due to their high kinetic energy and a diffusion transition layer is generated between the polymer and the metallization, resulting in a low contact resistance. A strong bond is obtained.

Theoretical energy density by volume of polymer systems is already relatively low, and this drawback affects even more acutely in practical polymer batteries, namely, many known electrode supports have a single layer of polymer supported thereon with a thickness of only a few μm. Due to the relatively large dead volume compared to , the specific volumetric energy density of actual polymer electrodes is particularly much lower than the theoretical value.

Problems to be Solved by the Invention: Therefore, the object of the present invention is to provide a substrate which can be used as a deposition base material in the anodization process in the same way as known metal molded bodies, on the premise that a single layer of polymer can be directly synthesized on the metal surface. In this case, due to its advantageous low specific gravity, the aluminum lead-out body should be maintained as the main body, and therefore at least the function of lead-out body and electrode support must be achieved by inexpensive materials with lower costs compared to precious metals. Must be.

Means for solving the problem: This object is solved according to the invention by the measures according to claim 1 or claim 7.

Two alternative methods are therefore provided with the same result with respect to the desired electrode quality in order to solve the said object.

Effect: The common advantage of the two inventive processes is first of all that in the aluminum derivative used a material with very high specific weight and volumetric conductivity is produced, which has at least a small sheet thickness. When used in the form of thin sheets of a few μm, and thus when the polymer films reach similar thicknesses, the volume ratio of polymer film:derivative material can be significantly greater than 1.

Under these conditions, the energy density of the polymer battery can be maintained within a suitable range.

Aluminum sheets of the desired quality, such as those purchased from manufacturers, are mechanically stable enough but are coated with an electrically insulating natural oxide film, which alone makes the sheets as delivered susceptible to anodization of organic materials. Prevents use as a substrate for polymerization. In this case an oxidized aluminum surface.

is highly stable and prevents further oxidation of the base metal.

By coating the aluminum substrate with an electronically conductive material, which surprisingly leaves this surface condition, this substrate assumes the role of a deposition substrate for the polymerization process and also serves as an electrode support during subsequent cell operation without a tendency to corrosion. It has become clear that we can obtain the ability to satisfy an unlimited number of functions of derivatives.

A large number of metals, in particular metals from the noble metal family, such as gold or platinum, but also nickel, chromium alloys or nickel-chromium alloys are suitable as the electronically conductive material of the coating reservoir. Coating the aluminum substrate can be carried out by vapor deposition or sputtering. Another suitable method is spraying or coating a suspension prepared from metal powder and a solvent using suitable stabilizers.

Carbon coatings are particularly advantageous. Carbon is used as graphite or carbon black and can be vapor deposited or sprayed or applied, especially in suspended form like metal. A similar technique is applied with conductive lacquers.

After this pretreatment, direct electrochemical polymerization coating of active organic electrode materials can be carried out satisfactorily from monomer solutions in inert organic solvents.

The adhesive strength of the polymer layer is further increased by heat treatment at 200-300° C. for several hours before coating the noble metal or heavy metal coated polymer according to one of the above methods;
The conductivity of the oxide film on aluminum can be increased.

The selective manufacturing method of the electrode according to the present invention is to first wash the aluminum substrate with caustic potash or noda solution to remove the natural oxide coating, and then coat the bright surface of the aluminum substrate with a polymer using the same electrochemical method. Consists of things. This is, of course, a relatively zero-contamination process. Nevertheless, here too an intimate bond is achieved between the metal surface and the polymer deposited thereon, which is far superior in quality to mechanical contact alone. For example, a test cell with a polypyrrole positive electrode formed by a polymeric coating of a washed aluminum support, a lithium negative electrode, and a Lie 104-propylene carbonate electrolyte, showed no increase in internal resistance during cycling and no absorption of A/ions by the electrolyte. The risk of corrosion of the derivative bodies is therefore virtually non-existent.

However, in a preferred embodiment of the electrode formation according to the invention, the brightly cleaned aluminum surface is first coated with a corrosion-stable heavy metal, and the polymer is first deposited on this substrate. Corrosion protection of the aluminum is not necessary in this case to prevent the possible formation of a thin layer of oxide on the heavy metal coating, as long as it is itself sufficiently electronically conductive.

Particularly advantageous heavy metals for the purposes of the invention are chromium and nickel-chromium alloys. Further advantageous, although limited by price, are precious metals, especially platinum.

Organic compounds which may be mentioned in particular for polymer formation within the scope of the invention are pyrrole, thiophene, furan, aniline and p-phenylene sulfide.

Surprisingly, by means of the present invention, conditions are obtained which make it possible for the first time to conduct electrochemical processes on the surface of the oxide film on the electrolyte side, even in the case of aluminum substrates with oxides attached and therefore corrosion-resistant. Since the oxide film and especially the overlying metal film are extremely thin, it is assumed that the flow of electrons required for anodic polymerization is achieved by tunneling through the oxide film between the coated metal layer and the metallic aluminum core. Must.

Example: The drawings particularly clarify this presumed fact.

This figure schematically shows a polymer electrode according to claim 1. This electrode features 1 aluminum metal, 2 natural oxide coatings, and 3 electronically conductive coatings (noble metal or carbon).
and electrochemically deposited polymer 4. After reaching a constant potential gradient between layers 1 and 3, the electrons pass through the non-conductive oxide layer 2, in which the tunnel section 5 extends, and exit via the aluminum conductor 1.

Instead of sheets, A/net or Al! treated according to the invention can be used to improve the adhesion of the polymer to the substrate. It is advantageous to use an expanded method. In this case, the polymer film conforms to the net or expanded metal web and can no longer be peeled off from the support.

Although this method of combining the conductor material and the electrode material necessarily leaves a mesh space, this space can be used with great advantage as an electrolyte reservoir. This is because polymer electrodes each require a certain amount of electrolyte for charging, and this electrolyte is kept available in the immediate vicinity of the electrode by distributing it to the mesh. In this sense, during the production of Al net or Al expander lattice, the space between the mesh openings is formed to a size such that the stoichiometric amount of electrolyte required for electrode operation will fit into this hollow space. is advantageous. Electrodes configured in this manner help significantly increase the power density of polymer cells. This is because this electrode integrates at least a portion of the electrolyte as active ingredient, whereas otherwise only porous separators could be used to accommodate the active ingredient. Therefore, the separator can have a small thickness with low resistance as an inert component.

The alternative method for producing the polymer electrode according to claim 7 of the invention starts from an aluminum conductor which is preferably present as a sheet in the form of a net or an expanded metal. In the as-delivered state, the base metal is protected by a natural oxide film, which prevents the use of aluminum in combination with a nonconductor as a conductive support for electrochemically active materials directly or without pretreatment.

According to the invention, the pretreatment consists of thorough removal by cleaning of the natural oxide film. Potash or soda liquid is used as the cleaning liquid. After thorough water washing, the aluminum derivatives are not dried before the polymer coating or polymerization coating, and the electroplating method of coating with the heavy metal layer is first carried out.

In this way, the porosity-free coated derivative, pretreated with eg chromium, can bond strongly with the active polymer. Direct electrochemical polymeric coating of electrode materials can likewise be carried out satisfactorily with derivatives treated according to the invention as substrates deposited from monomer solutions in the same solvent as that of the battery electrolyte.

The polymeric electrodes with heavy metal coating of the aluminum support according to the invention also have the particular advantage of being stable against traces of moisture in the organic electrolyte, which cannot be maintained tolerably within the eye without considerable expense.

[Brief explanation of the drawing]

The drawing is a cross-sectional view of a polymer electrode according to the invention. 1... Aluminum base material 2... Oxide film 3...
Electron conductive coating 4... Polymer 5... Tunnel section 191. Aluminum base material

Claims (1)

[Scope of Claims] 1. A battery in which the active material is composed of a conductive organic polymer compound with a polyconjugated structure capable of doping with cations or anions, and has at least one electrode comprising an aluminum derivative, in which each of the polymer compounds is the base. 1. A cell having a polymer electrode formed by electrochemical deposition on an aluminum substrate, which retains a natural oxide film, but is provided with an electronically conductive coating, from monomers containing the same material. 2. A battery according to claim 1, wherein the electronically conductive coating consists of a metal, which metal is applied to the aluminum substrate by vapor deposition, sputtering, or by spraying or coating a suspension prepared with a solvent. 3. Claims in which the electronically conductive coating is carbon in the form of graphite or carbon black, which is vapor deposited on the oxide-bearing aluminum substrate or sprayed or applied from a suspension prepared with a solvent. The battery according to item 1. 4. The battery according to any one of claims 1 to 3, wherein the aluminum base material is an aluminum sheet material, a net, or an expanded metal. 5. The battery according to claim 4, wherein the dimensions of the spaces in the net or expanded metal mesh are adjusted according to the volume of electrolyte required for charging the polymer electrode. 6. The monomer on which the polymer compound is based is pyrrole,
A battery according to any one of claims 1 to 5, wherein the battery is selected from the group of thiophene, furan, aniline, p-phenylene sulfide. 7. In a battery in which the active material consists of a conductive organic polymer compound of polyconjugated structure which can be doped with cations or anions and has at least one electrode comprising an aluminum derivative, the polymer compounds are each washed from the monomer on which they are based. 1. A battery having a polymer electrode formed by electrochemical deposition on a bright aluminum substrate from which a natural oxide film has been removed, either directly or after being coated with a corrosion-stable heavy metal. 8. The battery according to claim 7, wherein the corrosion-stable heavy metal is chromium, a nickel-chromium alloy, or a noble metal. 9. The battery according to claim 7 or 8, wherein the aluminum base material is an aluminum sheet material, a net, or an expanded metal. 10. The battery according to claim 9, wherein the dimensions of the spaces in the net or expanded metal mesh are adjusted according to the volume of electrolyte required for charging the polymer electrode. 11. A battery according to any one of claims 7 to 10, wherein the monomer on which the polymer compound is based is selected from the group of pyrrole, thiophene, furan, aniline, p-phenylene sulfide. 12. In a method for producing a battery in which the active material is made of a conductive organic polymer compound with a polyconjugated structure that can be doped with cations or anions, and in which at least one electrode is provided with an aluminum derivative, an aluminum group with a natural oxide film attached is used. 1. A process for producing a battery with polymeric electrodes, characterized in that an electron-conducting coating is provided on a material and an organic polymer compound is electrochemically deposited onto this coating from the respective base monomer. 13. A method for producing a battery in which the active material is made of a conductive organic polymer compound with a polyconjugated structure that can be doped with cations or anions, and has at least one electrode comprising an aluminum derivative, in which the aluminum base material is washed with an alkaline solution. Then, the natural oxide film is removed,
A method for producing a battery with a polymer electrode, characterized in that monomers each based on an organic polymer compound are deposited electrochemically on a brightly cleaned aluminum surface, either directly or after being coated with a corrosion-stable heavy metal by electroplating. .