Abstract: The invention relates to an additive, to be added to conventional electrolytes of alkaline secondary zinc cells or to alkaline zinc plating baths, adapted to establish in said liquids a minimum concentration of 10.sup.-6 M per liter of cobalt ions and a minimum concentration of 5.10.sup.-6 M per liter of cadmium ions, said additive being a coprecipitate of cobalt hydroxide and cadmium hydroxide and either magnesium hydroxide or calcium hydroxide, to electrolytes for alkaline secondary zinc cells and alkaline zinc plating baths containing such additives and to a process for the production of such additives.

Abstract: The invention relates to mixed oxides of the spinel type or of similar structure, containing a quantity of boron adapted to reduce the electrical resistance of the oxide by a factor of at least 1000 calculated on the corresponding compound without boron, some of the preferred compounds being selected from compounds of the formulae Co.sub.x Fe.sub.3-x O.sub.n and Co.sub.x Ni.sub.3-x O.sub.n, wherein x is between 0.05 and 3, n is between 3 and 5, containing from 0.05 to 20 atom per cent boron calculated on the mixed oxides, wherein part of the Co,Ni. or Fe may be substituted by an equivalent quantity of magnesium or calcium, said compounds being optionally doped with lithium; electrocatalytically active electrodes made from such compounds and electrical cells containing such electrodes.