Improvements in or relating to porous electrodes for electrochemical cells

Abstract

Abstract A porous electrode for an electro-chemical cell using a liquid electrolyte and gaseous reactant, e.g. a fuel cell or primary or secondary battery, is made by forming a mixture of particles of metal, e.g. stainless steel, Co, Ag or Ni, and particles of noncrystalline carbon which is subject to electrolytic attack, into a self-supporting structure using heat, and subjecting the structure to electrolysis as an anode in a liquid electrolyte, without attacking the metal e.g. KOH solution, to remove the carbon and leave a porous metal matrix. Preferably between 3 and 20 parts by weight of carbonyl Ni powder less than 10 micron size are used for each part of charcoal of maximum particle size 20 microns in the mixture, and for electrodes between 0.2 and 2mm. thick the mixture is hot-pressed e.g. using a graphite die at between 200 and 5000 p.s.i. and between 300 and 800 DEG C. A material catalysing an electro-chemical reaction may be included as particles in the mixture or deposited upon the metal matrix, e.g. graphite, Mn, Ag, Pt or Pd. The deposition may be effected by coating the metal matrix with an organic salt e.g. resinate or halogeno mercaptide-alkyl sulphide of a platinum group metal using an organic solvent and impregnating and decomposing with heat; or by electro-plating with a platinum group metal e.g. from a solution containing PdCl2, Na2 HPO4, (NH4)2 HPO4 and benzoic acid, or with Ag e.g. from a solution containing AgCN, KCN and KOH.

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