GB1466456A - Electrochemical cells - Google Patents

Abstract

1466456 Electrodes for hybrid cells PPG INDUSTRIES Ine 18 Sept 1974 [19 Sept 1973] 40619/74 Heading H1B In a secondary cell, the cathode is made of an electrolyte impermeable silicon or silicon alloy substrate with at least a partial coating of an electroconductive or electrocatalytic material on its surface. Preferred example.-A rechargeable brominezinc cell has a cathode comprising a silicon alloy substrate containing 0À3 weight per cent boron and 8 weight per cent iron carrying a ruthenium dioxide-titanium dioxide coating (process for applying described). The cathode and a zinc anode are in a 2 normal aqueous zinc bromide electrolyte on top of a carbon disulphide layer. Other examples. Cathode-substrate: silicon doped with <2% nitrogen, phosphorus, aluminium or boron; silicon-silicide alloys containing 2 to 30% titanium, zirconium, hafnium, vanadium, columbium, tantolium, chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, ruthenium, rhodium, palladium, osmium, iridium, platinum, gold or silver. Electrocatalytic layer: platinum, ruthenium, rhodium, palladium, osmium, iridium or an alloy of 10-20% iridium balance platinum, oxides thereof and mixtures of oxides, e.g. crystalline combination of platinum dioxide and palladium dioxide; delafossites; pyrochlores; perovskites; mixtures of oxygen-containing compounds of platinum group metals with oxides of titanium, tungsten, zirconium, hafnium, vanadium, columbium, molybdenum or chromium; magnetite, spinels. 5, 10 or 20% of the substrate surface may be coated, thickness 5 or 10 microinches. Anode: zinc, graphite coated with zinc, silicon coated with zinc. Electrolyte: any zinc halide, oxyhalate, peroxide. Electrolyte - insoluble phase: chloroform, bromoform, iodoform, carbon tetrachloride, carbon tetrabromide, perchloroethylene, perbromoethylene. If zinc chloride electrolyte used-compressed or liquefied chlorine cylinder. Diaphragm between electrodes may be permionic perfluorinated, sulphonated hydrocarbons or perfluorinated sulphonated styrene. Electrolyte-permeable barriers also mentioned. Bipolar electrodes.-A silicon substrate coated with ruthenium dioxide-titanium dioxide on one side and zinc on the other side.