Electrochemical cell having an electrode containing a carbon fiber paper coated with catalytic metal particles
AssigneeThe Dow Chemical Company
InventorsRobert D. Door, Glenn A. Eisman
Life of this patent
Estimating the term…
Abstract
An electrochemical cell having at least one electrode containing a carbon fiber paper coated with an uncoagulated mixture of binder and catalytically active metal particles provides superior voltage characteristics at catalyst/binder ratios of about 2/1 to about 25/1.
Claims22
A process for producing an electrode comprising:
- (A) preparing a uniformly coated carbon fiber paper by applying an uncoagulated aqueous mixture consisting essentially of catalytic metal particles and a hydrophobic or hydrophilic resin binder to one side of a wet proofed carbon fiber paper, wherein said carbon fiber paper is wet proofed by coating or impregnation with a hydrophobic polymer and said catalytic metal particles are present on said coated carbon fiber paper in the amount of about 2 to about 25 parts by weight of said metal particles per part of said resin and
- (B) heating said coated carbon fiber paper to a temperature of 275.degree.-350.degree. C. to sinter the binder.
An electrode for an electrochemical cell comprising a solid polymer electrolyte membrane bonded to the coated side of a wet-proofed carbon fiber paper, said coated side having a uniform coating prepared by coating said side with an uncoagulated, aqueous mixture consisting essentially of catalytic metal particles and a hydrophilic or hydrophobic resin binder, wherein said catalytic metal particles are present in said coating in the amount of about 4 to about 25 parts by weight of said catalytic metal particles per part of hydrophilic or hydrophobic resin.
A gaseous fuel cell comprising an aqueous electrolyte positioned between and in direct electrical contact with a pair of gas diffusion hydrophobic, electrically conductive electrode elements, each of said electrode elements consisting essentially of a coated, wet proofed carbon fiber paper, wherein said paper is prepared by uniformly coating on one side with an uncoagulated aqueous mixture comprising catalytic metal particles and a hydrophobic resin binder, said metal particles and said hydrophobic resin being present in a coating on said paper on a weight basis, of about 2 to about 25 metal particles per part of hydrophobic resin, means for supplying a fuel gas to one of said electrode elements, and means for supplying an oxidant gas to the other of said electrode elements.
A membrane/electrode assembly comprising:
- (A) an electrically conductive, wet-proofed carbon fiber paper having a single, uniformly coated side wherein the coating on said side is prepared by coating said side with an uncoagulated, aqueous mixture consisting essentially of catalytic metal particles and a hydrophobic or hydrophilic resin binder, said metal particles and resin binder being present in the amount of about 2 to about 25 parts by weight of said metal particles per part of hydrophobic or hydrophilic resin and
- (B) an ion exchange membrane bonded to said coated side of said wet-proofed carbon fiber paper.
A method of generating an electric current comprising feeding streams of a fuel gas and an oxidant gas to a fuel cell, said fuel cell having at least two electrodes and a catalytic metal coating layer on one side of said electrodes and an electrolyte-containing matrix between said electrodes, said coating consisting essentially of a catalytic metal particle and binder and coated on a wet proofed carbon fiber paper wherein said binder comprises a hydrophobic polymer, said method comprising:
- (A) oxidizing a fuel at the catalytic metal particle and binder coating of one electrode to generate a stream of electrons,
- (B) conducting the electrons to a second electrode,
- (C) combining the electrons with said oxidant at the catalytic metal particle and binder coating of the second electrode, and
- (D) transferring ionic species through the electrolyte to complete the circuit,
- wherein said electrodes are prepared by applying a coating to said carbon fiber paper from an uncoagulated slurry of said hydrophobic polymer and said catalytic metal particles, said coating being uniformly applied by utilizing spray, metering bar, metering knife, or metering rod application means and, thereafter, heating said carbon fiber paper and said catalytic metal coating layer to a temperature of 275.degree. C.-350.degree. C. to sinter the binder.
An assembly for bonding a membrane and electrode assembly at elevated temperature, said assembly comprising:
- (A) a membrane and electrode assembly comprising an ion exchange membrane sandwiched between the coated sides of two layers of a carbon fiber paper coated with a catalytic layer, said coated sides having a uniform coating prepared by coating said sides with an uncoagulated aqueous mixture consisting essentially of catalytic metal particles and a hydrophilic or hydrophobic resin binder wherein said catalytic metal particles are present in said coating in an amount of 2 to about 25 parts by weight of said catalytic metal particles per part of hydrophilic or hydrophobic resin,
- (B) sandwiched layers of a release paper impregnated with polytetraflourethylene, each of said layers positioned externally to said membrane and electrode assembly, and
- (C) overlaying layers of a silicone rubber sheet on said release paper, each of said silicone rubber layers overlayed with a rigid metal sheet.
Dependencies are inferred from the claim text.