GAS-DIFFUSION PLATE AND ITS MANUFACTURING PROCESS Russian patent published in 2001 - IPC

FIELD: electrical engineering; chemical power supplies. SUBSTANCE: gas-diffusion plate has active layer including 85-98% of activated carbon and carbon black with specific surface area of 200-2000 sq.m/g, black- carbon content being 5 to 90%, 1.5-10% of high-molecular polyethylene, and 0.5-5% of polyisobutylene or butyl rubber as stabilizing additive; water-repelling layer including 60-90% of commercial-grade carbon, 5- 25% of high-molecular polyethylene, 3.5-10% of graphite, and 1.5-5% of polyisobutylene or butyl rubber as stabilizing additive; terminal grid. Active layer may have, in addition, catalyst in the amount of 0.1 to 5% of its carbon black content. Used as catalyst may be metal of silver- containing group, platinum-group metals, their mixtures or alloys based on them. Terminal grid may be placed between active and water-repelling layers or inside active or water-repelling layer. Used as terminal grid may be nickel grid compressed to 20-80% of initial thickness. Porosity of water-repelling layer is higher than that of active layer; total porosity of plate is 60-80%. Pore size in active and water-repelling layers is between 0.001 and 1 mcm. Plate manufacturing process includes mixing up activated carbon, carbon black, high-molecular polyethylene, and stabilizing additive for active layer and also mixing up commercial-grade carbon, graphite, high-molecular polyethylene, and stabilizing additive for water-repelling layer in above-mentioned proportions, granulating the mixtures, press-fitting granulated mixtures obtained in the process on one or both sides of terminal grid at high temperature, extracting oil from plate by means of solvent, and compressing the plate at 110-170 C and at specific pressure of 100-500 kg/sq. cm. Prior to mixing up ingredients carbon black may be impregnated with glycerin, mass content of both being 0.3 to 1; upon oil extraction plate is rinsed to remove glycerin and dried out. EFFECT: extended service life of plate. 20 cl