JPS6325076B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention minimizes the electrical resistance between current collection means and embedded or bonded electrodes used in electrolytic SPE cells. The present invention relates to a method of manufacturing a solid polymer electrolyte (SPE) structure.

[Conventional technology]

A solid polymer electrolyte (SPE) battery is one in which one or two electrodes are bonded within a polymeric ion exchange membrane.
Or an embedded battery. Such batteries are well known in the art and are described in the following US patents.

No. 4315805, Darlington et al. (February 1982)
16th) No. 4364815, Darlington et al. (December 1982)
12) No. 4272353, Lawrence et al. (June 9, 1981) and No. 4394229, Korach (July 19, 1983) In SPE cells, the current collecting means is pressed towards and in contact with the electrode. , forming a path for current to flow from the power supply to the electrodes. The current collection means is an electrically conductive, water permeable matrix which can take a variety of shapes, sizes and formats, such as metal window screens, perforated metal plates, expanded metal, etc. and their analogs. The following US patents describe examples of commonly used current collection means.

No. 4299674, Korach (November 10, 1981) No. 4468311, de Nora et al. (August 28, 1984)
No. 4215183, Mac Leod (July 29, 1980) SPE batteries often suffer from high electrical resistance between the embedded or bonded electrode and the current collection means pressed towards the electrode. There are big problems caused by this. Many skilled in the art have attempted to solve this high resistance problem by various methods.
One version of this solution is U.S. Pat. No. 4,468,311;
Using pine tresses as shown in Nora et al. (August 28, 1984) or U.S. Pat. No. 4,239,396, Allen et al. (October 6, 1981).
and the application of an electrocatalyst directly to a conductive carbon fabric that acts as a current collection means, as described in .

[Problem that the invention seeks to solve]

The present invention provides an electrolytic SPE battery with a solid polymer electrolyte (SPE) structure capable of minimizing the electrical resistance between the current collecting means used therein and the embedded or bonded electrodes. It aims to provide a method for manufacturing products.

[Means for solving problems]

The present invention is a method for manufacturing a solid polymer electrolyte structure to solve the above problems, and includes the following steps: (a) forming a suspension from conductive particles having catalytic activity and a liquid; (b) applying said suspension onto at least one side of a fluorocarbon polymer membrane while said membrane is in its thermoplastic, plastically deformable state; and (c) applying said suspension to said membrane. removing substantially all of the liquid while leaving the particles thereon; and (d) pressing at least a portion of the particles into the membrane, wherein the liquid is 1,2- It is characterized by being selected from dibromotetrafluoroethane and 1,2,2-trichlorotrifluoroethane.

In the method of the present invention, if necessary, a conductive, water-permeable matrix may be bonded to the surface of the membrane which has been treated as described above and has the particles on its surface.

[Function and Examples]

In the accompanying drawings, a solid polymer electrolyte structure 100 of the present invention includes a solid polymer membrane 120, a plurality of conductive particles 110, and a conductive water permeable matrix 130.

Resistance to the flow of electrical energy as a result of the close contact between the polymer membrane and the conductive particles and the conductive water-permeable matrix, which acts as a current collector and is connected to a power supply source. is minimized, so the cell operates more efficiently than cells using prior art SPE structures.

The SPE structures (electrodes) of the present invention include embodiments in which conductive particles are bound or embedded on one or both sides of a polymer membrane.

The attached drawing shows such an SPE structure (electrode) 1
Indicates 00. This structure includes a polymer film 120 and a number of conductive particles 110 embedded therein.
It has the following.

The particles 110 are in physical and electrical contact with a conductive water permeable matrix 130 which is also embedded within the membrane 120.

The membrane separates the anode compartment from the cathode compartment and limits the types and amounts of fluids and/or ions that can pass between the anode and cathode compartments. The membrane may be a single layer membrane or a multilayer composite membrane.

The membrane may be constructed from a fluorocarbon-based polymeric material or a hydrocarbon-based polymeric material. Such membrane raw materials are well known in the art. Preferably, however, fluorocarbon-based polymeric materials are commonly used because of their good chemical stability.

The nonionic (thermoplastic) perfluorinated polymers described in the patents listed below are suitable for use in the present invention.

US Patent No. 3282875; 3909378; 4025405;
4065366; 4116888; 4123336; 4126588;
4151052; 4176215; 4178218; 4192725;
4209635; 4212713; 4251333; 4270996;
4329435; 4330654; 4337137; 4337211;
4340680; 4357218; 4358412; 4358545;
4417969; 4462877; 4470889; and 4478695,
and European Patent Application No. 0027009. These polymers usually have equivalent weight values in the range 500 to 2000.

In order to enable the conductive particles to be embedded in the fluorocarbon polymer film, it is desirable that the fluorocarbon polymer film be in a state where it can be plastically deformed due to its thermoplasticity. The fluorocarbon polymer membrane is in a plastically deformable state due to its thermoplastic nature when it is manufactured and before it is formed into an ion exchange state. When in this plastically deformable state, for example, the membrane has ionically bonded
rather than SO ₃ Na or SO ₃ H side chain groups.
SO ₂ X side chain group (where X is -F, -CO ₂ ,
-represents CH ₃ or a quaternary amine).

A particularly preferred fluorocarbon polymer material for use in forming the membrane is a copolymer of a first type of monomer () and a second type of monomer () described below. If necessary, a third type of monomer () may be copolymerized with monomers () and ().

The first type of monomer () is represented by the following general formula.

CF ₂ =CZZ' () However, in the above formula, Z and Z' are each independently selected from -H, -Cl, -F, and -CF ₃ .

The second type of monomer () consists of one or more monomers selected from compounds represented by the following general formula.

Y—(CF ₂ ) _a —(CFR) _b —(CFR′) _c —O—[CF(CF ₂ X) —CF ₂ —O _o ]—CF=CF ₂ () However, in the above formula, Y is— SO ₂ Z″, ―CN, ―COZ″,
and -C( ^R3 )( ^R4 )OH, Z'' is selected from I, Br, Cl, F, -OR and _-NR1R2 , and R is a branched chain having _{1 to} 10 carbon atoms. a straight-chain or straight-chain alkyl group or aryl group, R ³ and R ⁴ are each independently selected from perfluoroalkyl groups having 1 to 10 carbon atoms;
R ₁ and R ₂ are each independently H,1~
selected from branched and straight-chain alkyl groups having 10 carbon atoms, and aryl groups, and a represents a number of 0 to 6, b represents a number of 0 to 6, and c represents a number of 0 or 1, provided that a+b+c is not equal to 0, X is
selected from Cl, Br and F, and mixtures thereof when n>1, where n is a number from 0 to 6;
R and R' are independently Br, F,
Cl, perfluoroalkyl groups having 1 to 10 carbon atoms, and fluorochloroalkyl groups having 1 to 10 carbon atoms.

Particularly preferably, in the above formula, Y is -
SO ₂ F or -COOCH ₃ , n is 0 or 1, R and R' are F, and X is
A monomer which is Cl or F and a+b+c is 2 or 3.

The third type of monomer () used if necessary is preferably composed of one or more monomers selected from compounds represented by the following general formula.

Y _′ -(CF ₂ ) _a ′-(CFR) _b ′-(CFR′) _{c ′ -O-} [CF(CF ₂ In the formula, Y' is selected from F, Cl and Br,
a' and b' are each independently a number from 0 to 3, and c' is 0 or 1, provided that a'+b'+c' is never equal to 0, and n' is a number from 0 to 6. is the number of
R and R' are the same as above, and X' is F, Cl,
and Br, and a mixture thereof when n'>1.

The method of converting the Y group into an ion exchange group is well known in the art and consists of reacting the Y group with an alkaline solution. It has been found that 1,2-dibromotetrafluoroethane and 1,2,2-trichlorotrifluoroethane are good solvents for polymers made from the monomers mentioned above.

While the fluorocarbon polymer film is thermoplastically capable of plastic deformation, it can be heated to soften it and cooled to harden it. Therefore, particles can be easily forced into the membrane when the membrane is heated. The temperature at which the membrane is heated to sufficiently soften the membrane and allow particle embedding will vary depending largely on the chemical structure of the membrane. However, in general, in a film composed of a monomer having the chemical structure of the above formula (), when Y=-SO ₂ F, 150 to
Heating temperatures in the range of 350°C are used. Membranes based on hydrocarbon polymers are heated to temperatures ranging from 100°C to 190°C, depending on the exact composition of the hydrocarbon material. For example, a polymeric membrane may be coated as described in U.S. Pat.
A sulfonyl fluoride powder having an equivalent weight of 1000 was heated between two glass fiber-reinforced polytetrafluoroethylene sheets at a temperature of about 310°C.
and may be produced by heating and pressurizing for about 1.25 minutes under a pressure of about 0.75 tons per square inch (6.4516 cm ² ) (13335 KPa). The membrane bodies obtained in this way have a diameter of 15 cm to 18 cm.
0.0025mm~0.4mm preferably 0.01~0.25mm
, most preferably having a thickness of 0.05 to 0.15 mm.

In the present invention, it is important to provide an effective bond between the conductive, water-permeable matrix and the membrane. Such bonding may be accomplished with or without external pressure treatment during the bonding operation. However, the best bonding is generally achieved by first contacting the membrane with the conductive, water-permeable matrix, heating without pressure for about 1 minute, and then applying 1 ^to 8 particles per square inch. 0.2-2 at ton pressure
It has been found that this can be obtained by applying pressure for minutes.

The present invention requires that at least one of the electrodes be in the form of a multiplicity of electrically conductive particles embedded in a polymeric membrane. This constitutes the SPE electrode. The electrode made of a large number of conductive particles may be either a cathode or an anode. Optionally, both electrodes may be conductive particles embedded on opposite sides of the membrane. For the purpose of this description, the shape of both electrodes may be described such that both electrodes are conductive particles, and may be described such that both electrodes are separate conventional electrodes. Sometimes.

Conventional anodes are typically water-permeable, electrically conductive structures, such as sheets of expanded metal, perforated plates, punched plates, or diamond-shaped non-flattened expanded plates. They are formed in a variety of shapes and styles, including solid metal or woven metal wire.
Metals suitable for use as an anode include tantalum, tungsten, columbilum, zirconium, molybdenum, and, preferably, titanium, and alloys containing these metals as a majority component.

If desired, the anode can be an SPE electrode consisting of a large number of conductive particles embedded in a membrane. Materials suitable for use as electrocatalytically active anode materials include, for example, activators such as oxides of platinum group metals, i.e., ruthenium, iridium, rhodium, platinum, palladium, etc.; These materials may be used alone or in combination with film-forming metal oxides. Other suitable activated oxides include cobalt oxide alone or in combination with other metal oxides. Examples of such activated oxides are U.S. Pat. No. 3,632,498;
It is described in No. 4142005, No. 4061549, and No. 4214971.

Conventional cathodes are typically made of, for example, sheets of expanded metal, perforated plates, punched plates, diamond-shaped non-flattened expanded metal, or woven metal wires. water permeable, electrically conductive structures formed in a variety of shapes and styles. Metals suitable for the cathode include, for example, copper, iron, nickel,
Lead, molybdenum, cobalt, and alloys containing these metals as a majority component, such as low carbon stainless steel, and metals coated with materials such as silver, gold, platinum, ruthenium, palladium, and rhodium, etc. Includes alloys, etc.

If desired, the cathode may be an SPE electrode consisting of a large number of conductive particles embedded in a polymeric membrane, as described above. Materials suitable for use as electrocatalytically active cathode materials include, for example, platinum group metals and their metal oxides, such as ruthenium and ruthenium oxide. Such a cathode is disclosed in US Pat. No. 4,465,580.

The conductive particles used as an anode or a cathode are preferably finely ground and have a large surface area. For example, oxygen
or in the case of hydrogen electrode fuel cells, platinum black with a surface area greater than 25 m ² /g or high surface area platinum (800-1800 m ² /g) on activated carbon powder (average particle size 10-30 microns) can be used as the anode and It is extremely suitable for use as a cathode. In the case of chlorine batteries, a coating may be applied, but in this case,
Ruthenium dioxide particles are prepared by pyrolysis of ruthenium nitrate at a temperature of 450° C. for 2 hours. The resulting oxide is ground using a mortar and pestle, and the portion that passes through a 325 mesh sieve (less than 44 microns) is used for making electrodes.

A conductive and water permeable matrix pressed against the surface of the membrane with embedded particles
Acting as a current collecting means to transfer electrical energy to or from the SPE electrode, it can be made of carbon fabric, carbon paper, carbon felt, metal screen,
It may be constructed from a variety of materials including metal felt, porous metal sheets, and the like. However, it is preferred that the conductive and water permeable matrix is a carbon fabric. it is,
This is because carbon fabrics are readily available, have good performance, are easy to handle, and are relatively inexpensive.

The fabric most preferably used in this invention is one that has low electrical resistance, is relatively inexpensive, has sufficient strength for use, and has suitable surface properties, such as roughness. This allows good bonding between the ion exchange membrane and the fabric itself. It is also preferred to have good electrical contact between the carbon fabric of the electrode and the electrocatalytically active particles.

A suitable type of carbon fabric for use in the present invention is Panex PWB from Stackpole Fibers.
3. Those sold under the names PWB-6, KFB and SWB-8, and WCA Graphitecloth and VCK and VCA from Union Carbide.
They are commercially available from a variety of sources, including those sold under the name carbon fabrics.
Carbon fabric is also available from Fiberite.
Celion1000, Celion3000, Celion6000,
Carbon fiber commercially available under names such as Celion 12000, or C-6 or G-50 from Celanese
It may be woven from carbon fibers commercially available under the name . These materials vary in physical properties, but as long as they are strong enough to maintain their physical shape during the manufacturing process, they are suitable for the present invention. can be used. Fiber size, weave pattern, etc. may also vary, but are not critical to the successful implementation of the invention. Fabrics useful in the present invention preferably have a thickness of 0.05 to 0.65 mm and an electrical resistance of 600,000 to 1375 microohm-cm.
More preferably, the fabric used in the present invention has about
It has a resistance of 1500 microohm-cm.

The SPE construct consists of conditioning a polymer membrane to a plastically deformable state due to its thermoplastic properties, embedding electrocatalytically active particles in the membrane, and then injecting the membrane with NaOH and It is produced by denaturing this membrane into an ionic state by reacting in this manner. This polymeric membrane, if it has --SO ₂ F side chain groups, can be converted to an ionic state by reacting it with NaOH under the following conditions.

Conditions (1) Place the membrane in approximately 25% sodium hydroxide solution at approximately 90%
Soak for about 16 hours at a temperature of °C.

Condition (2) The membrane is washed twice with deionized water heated to a temperature of about 90°C, for 30 minutes or more per wash.
Take 60 minutes.

Then, the side chain group (-SO ₂ F) becomes -
It takes the form of SO ₃ ^- Na ⁺ . Cations other than Na ⁺ , such as H ⁺ , can actually be replaced by Na ⁺ . If desired, instead of bonding the current collecting means to the particles, the current collecting means may be pressed towards the particles after the membrane has been converted to the ionic form.

Various techniques can be used, such as suspending the particles in a liquid, spraying or pouring the suspension onto the membrane, removing the liquid (which may be a solvent for the polymer), e.g. The electrocatalytically active particles may be incorporated onto the surface of the membrane using various techniques, such as evaporating away the carbon fabric and then forcing the particles into the membrane, where the membrane is incorporated with the carbon fabric. It may be a single object, or it may be an uncombined object. For example, platinum and carbon particles
2-dibromotetrafluoroethane or 1,2,
It may be dispersed in a liquid such as 2-trichlorotrifluoroethane and the suspension may be poured or sprayed onto the membrane. This liquid is then evaporated off. Next, a current collecting means made of carbon cloth may be pressed onto the electrode formed as described above.

The amount of particles used on the membrane to form the SPE electrode may vary depending on the activity of the electrocatalyst, its cost, etc. Chlor-alkali
For SPE membranes, the amount of catalyst used is typically 0.4 to 1.0 micrograms catalyst per square centimeter of membrane area. There is an upper limit to the amount of particles that can be applied onto the membrane to prevent particles from seeping into the membrane. This upper limit value is set at approximately 25 micrograms of catalyst per cm ² of membrane area.

〔Effect of the invention〕

The solid polymer electrolyte structure of the present invention includes, for example,
fuel cells for continuous production of electrical energy,
It is useful in a wide variety of electrochemical cells, including electrolytic cells for the production of chemical products, cells for the intermittent production of electrical energy, and the like.

[Brief explanation of the drawing]

The accompanying drawings are explanatory diagrams showing the structure of a solid polymer electrolyte structure obtained by the method of the present invention. 100... Electrode, 110... Conductive particles, 120...
Solid polymer membrane, 130... conductive/water permeable matrix.

Claims (1)

[Claims] 1. The following steps: (a) forming a suspension from conductive particles having catalytic activity and a liquid; (b) adding the suspension to at least one of the fluorocarbon polymer membranes; (c) removing substantially all of the liquid while leaving the particles on the membrane; and (d) pressing at least a portion of the particles into the membrane, wherein the liquid is selected from 1,2-dibromotetrafluoroethane and 1,2,2-trichlorotrifluoroethane. A method of manufacturing a solid polymer electrolyte structure, characterized in that: 2. The method according to claim 1, comprising the step of bonding the surface of said membrane which has been subjected to said treatment and has said particles thereon to an electrically conductive and water permeable matrix. 3. applying a pressure treatment to the membrane-matrix combination that is sufficient to embed at least a portion of the matrix into the membrane;
The method according to claim 2. 4. The matrix according to claim 3, wherein the matrix is selected from carbon fabric, carbon paper, carbon felt, metal mesh, metal felt and porous metal sheet and has a resistance of 600000 to 1375 micro-ohm-cm. Method. 5. The method of claim 3, wherein the matrix is a carbon fabric having a thickness of 0.05 to 0.65 mm. 6. The method of claim 3, 4 or 5, wherein the matrix has a resistance of about 1500 microohm-cm. 7 The film has a thickness of 0.0025 mm to 0.4 mm and a thickness of 500 mm to 0.4 mm.
Claims 1 to 6 having an equivalent value of 2000
The method described in any one of the paragraphs. 8. A method according to any one of claims 1 to 7, wherein the particles are applied to both sides of the membrane. 9. The catalytically active particles include platinum group metals, oxides of platinum group metals, ruthenium, iridium, rhodium, platinum, and palladium, each alone and in combination with a film-forming metal, cobalt oxide alone, and cobalt oxide alone and in combination with a film-forming metal. 9. The catalytically active particles are selected from combinations with other metals and have a particle size of 1 to 30 microns and a surface area of 800 to 1800 ^m2 /g. Method. 10. The method of claim 8 or 9, wherein the catalytically active particles are present on the membrane at a level of 0.4 to 25 milligrams per cm ² of surface area of the membrane. 11. According to claim 1, a plurality of conductive particles form a positive electrode on one side of the membrane sheet, and a plurality of conductive particles form a negative electrode on the opposite side of the membrane sheet. the method of. 12. The method of claim 1, wherein one of the electrodes is comprised of a plurality of conductive particles and the other electrode is comprised of a porous metal plate.