GB1360589A - Electro-chemical systems - Google Patents

Abstract

1360589 Electric cell electrodes UNION CARBIDE CORP 22 Dec 1972 [28 Dec 1971] 59369/72 Heading H1B Coherent electrodes for use in primary and secondary cells with aqueous electrolytes contain manganese dioxide (>70 wt. per cent), a particulate electrically conductive material (5-10 wt. per cent), an electrically conductive material of colloidal particle size (1-2 wt. per cent) and a polymeric binder (1-2 wt. per cent). Short fibres and silver oxide are optional further components of the electrode. A volatile solvent generally used in manufacture of the electrodes makes the electrodes porous as they are dried out but in the absence of such a solvent ammonium carbonate may be incorporated in the mix and thermally decomposed to give porosity. The electrode mix may be pressed about a current collector mesh or sandwiched between two of these. The collector body may be made of steel, nickel, carbon, or silver and may be coated with graphite, sintered metal powder, nickel or electroplated silver. (Tin-plated copper and tinplated steel are used to contact zinc anodes in examples.) The conductive particles in the electrode mix may be of graphite or acetylene black; the colloidal particles may be of graphite, carbon black, silver, or nickel, and the binder may be of a variety of resins (summarized in Claim 2). Anode materials used in examples are zinc (as powder + starch-gelled electrolyte; mesh; or plate), cadmium and magnesium (foils), and lead. Use of aluminium is suggested. Aqueous electrolytes used are 9N KOH; 9N KOH + 1 wt. per cent ZnO; 20 wt. per cent H 2 SO 4 ; and 4N MgBr 2 . Separators used are made of fibrousreinforced regenerated cellulose; modacrylic fibre; and methacrylate radiation-grafted on to cellulose. A zinc anode spirally wound (primary) cell with tin-plated steel can is described, as are various cells in flat (plastics-cased) and single and multicell plastics-housed forms (see Figs. 1 to 4, 15 and 16; not shown).