FABRICATION DES ELECTRODES A GAZ POUR PILES A COMBUSTIBLES

摘要

1321315 Fuel cell electrodes COMPAGNIE GENERALE D'ELECTRICITE 20 Nov 1970 [21 Nov 1969] 55419/70 Heading H1B A gas electrode for a fuel cell is made by a process comprising forming an aqueous suspension of a fibrous compound capable of being carbonized, preferably a cellulosic compound, e.g. paper pulp, or a polyamide based compound; forming a suspension comprising a water-repellent agent, e.g. P.T.F.E., in a wetting agent, e.g. alkylphenoxypolyethoxyethanol, and mixing to - gether the two suspensions. The P.T.F.E. may be in the solid state in the form of granules of diameter 35 microns or may be in the form of an emulsion comprising grains of 0À3 microns in an aqueous solution of ammonia. Particles providing the catalytic and conductive properties of the electrode are added to the mixed suspensions, these particles may comprise acetylene black containing 8% by weight of silver. When the P.T.F.E. is in the form of an emulsion, acetone is now added to gelatinize the emulsion. This mixture is deposited as a layer on a liquid-permeable conductive support of the electrode. This support may comprise a thin plate of sintered nickel or of graphite gauze. The liquid is removed from the layer by subjecting the uncoated side of the support to a vacuum and by drying at 100‹ C. Finally, the electrode is heated at 380‹ C. under a nitrogen atmosphere containing hydrogen to produce carbonization of the fibrous compound whereby the porous volume of the layer is increased.