Cobalt cathode prodn. for alkaline accumulator - by impregnating support with aluminium salt soln. before cobalt and aluminium salt soln. to increase capacity

摘要

Prodn. of a Co cathode for alkaline accumulators involves immersing a porous electrically conductive support in a soln. of a Co salt and Al salt(s) in a solvent and then pptg. the hydroxides in an alkaline medium, as in DT2731063. The novel feature is that the support is preimpregnated with a soln. contg. an Al salt. The ampere-hour capacity of the cathode is increased by ca. 10%. In an example, a thin rectangular plate of spongy Ni cross-sectional area 7.25 cm2; dry mass 1.8 g) was preimpregnated with an aq. soln. of Al(NO3)3.9H2O (density 1.153 g/cm3) for 1 min at 80-90 degrees C then impregnated with a soln. of 5 g Co(NO3)2.6H2O in 2 cm3 acetone and 2 cm3 aq. soln. of AlCl3 (density 1.275 g/cm3) for 3-5 min. After max. 30 min., the electrode was dipped in alkaline soln. (e.g. aq. KOH, NaOH and/or LiOH) at 40-80 degrees C for ca. 30 min. to ppte. the hydroxides. The wet mass of the electrode gas then ca. 3.6 g and the specific capacity 108 Ah/kg (cf. ca. 100 Ah/kg is preimpregnation was omitted).