886,463. Batteries. ELECTRIC STORAGE BATTERY CO. Feb. 3, 1960 [March 23, 1959], No. 3904/60. Class 53. In a storage battery in which the negative electrode is subject to treeing or the growth of surface projections the electrode is given a porous structure, the pores being filled with a cellulosic material. The electrode may consist of porous zinc which is impregnated with a solution of the cellulosic material which is then precipitated in the pores of the zinc. The electrode may be made by pressing powdered zinc into a grid or by agglomerating zinc particles with a binder or by sintering zinc oxide and then reducing it to metallic zinc by electrolysis. The cellulosic material may be made from cotton linters which are first steeped in sodium hydroxide solution in an atmosphere of steam. The alkali cellulose thus formed is dried and treated with carbon bisulphide to form a cellulose xanthate solution with which the zinc electrode is impregnated. The impregnated electrode is finally treated with sulphuric acid which precipitates cellulose in the pores of the zinc. In another method the cellulose is converted into the nitrate which is dissolved in a mixture of ether and alcohol to form a collodion solution with which the zinc electrode is impregnated. The electrode is then dried to remove the solvent, and may be enclosed in a cellulose wrapper. The cellulosic fillings may also be applied to porous cadmium electrodes.
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