Patent GB-1394694-A (GB)
Title: Lead acid accumulator or storage battery with supporting and/or connecting parts made of lihgt alloys
IPC: H01M50/50
Filed: 1972-10-27
Abstract: 1394694 Electrode grids and terminals for lead-acid batteries MONTECATINI EDISON SpA 27 Oct 1972 [28 Oct 1971 23 June 1972] 49773/72 Heading H1B [Also in Division C7] Support grids or electrode connections in a lead-acid storage battery are made of an aluminium and silicon base alloy the surface of which is covered directly or indirectly with a lead coating, the alloy having a minimum aluminium content of 80 wt. per cent and having a silicon content in the range 2-20 wt. per cent The alloy may contain one or more of magnesium, manganese, copper, nickel, iron, chromium and cobalt up to a total of 10 wt. per cent. the content of an individual element being less than 3À3 wt. per cent. One or more zinc or tin layers may be interposed between the alloy and the lead coating. Grids made of the material may be pasted conventionally, the spongy lead plate being produced from a paste of lead oxides and sulphuric acid and the lead dioxide plate being produced from a paste of sulphuric acid, carbon black, lead oxides, and expanders. Parts may be formed by casting, hot or cold working, or by sintering. Particular alloy compositions contain aluminium and, by weight, (a) 12% Si, 0À3% Mg, 0À5% Mn; (b) 7% Si, 0À3 Mg, 0À5% Mn, 0À15% Ti; (c) 11À5% Si, 1À6% Cu, 1À0% Ni, 0À5%Mg, 0À2% Fe; (d) 11À5% Si, 1À5% Cu, 1À0% Ni, 1À0% Mg, 0À4% Fe; (e) 10% Si, 2À2% Cu, 1À4% Mg, 1À0% Ni; (f) 12% Si, 2À0% Cu, 0À7% Fe; (g) 6% Si; (h) 13% Si. Electrode grids are made by melting an aluminium-silicon alloy, adding sodium fluoride and sodium chloride, stirring vigorously, and then allowing the melt to stand. After removal of slag the alloy is poured into cast iron moulds. Cleaned and degreased parts may be pickled, either in an aqueous solution containing 5 wt. per cent ferric chloride and 35 wt. per cent hydrogen chloride or by alternate treatments in (a) 120 g ammonium bifluoride, 250 cc. 98% sulphuric acid, 500 cc. 90% nitric acid, and water to one litre; and (b) 2À5 cc. 36% hydrochloric acid, 80 g trichloracetic acid, 250 cc. lactic acid, and water to one litre. Two chemiplating compositions are described: (a) 77À5 g. basic lead carbonate, 20 g. boric acid; 100cc. 50 wt. per cent fluoboric acid, 500 g. water, 2 g. gum arabic; and (b) 18 g. basic lead carbonate, 8 g. sodium hydroxide, 176 g. tribasic dihydrated sodium citrate, 5 g. albumin, water to one litre and adjustment to pH 12 by the addition of tartaric acid. Three electroplating methods are described:- (a) on to a chemiplated lead layer using 10A.- cm<SP>-2</SP>, a lead anode, and a composition containing 200 g. basic lead carbonate, 100 g. sulphamic acid, 200 g. glacial acetic acid, and 2000 g. water, at 25-30 C.; (b) on to a lead layer using 15 mA. cm<SP>-2</SP>, a lead anode and a composition containing 150 g. basic lead carbonate, 240 g. 50% hydrofluoric acid, 106 g. boric acid, 0À2 g. glue, and water to one litre, at 25-30 C.; and (c) direct on to the alloy using 1A.cm<SP>-2</SP> and a composition containing 160 g. sulphamic acid, 230 g. lead monoxide, 2 g. resorcinol, 0À5 g. glue, and water to one litre, at room temperature.