Metal hydride batteries comprising an electrolyte composition which comprises an aqueous solution comprising one or more compounds selected from the group consisting of metal hydroxides, metal oxide/hydroxides and ammonium hydroxides where when the electrolyte composition comprises KOH, the composition also comprises a further compound selected from the group consisting of metal hydroxides, metal oxide/hydroxides and ammonium hydroxides, exhibit reduced degradation of the anode material during operation. Anode materials advantageously exhibit .ltoreq.95% of the degradation of the same anode material in the same battery when replacing the electrolyte composition with 6 M aqueous KOH and exhibit conductivity of .gtoreq.50% of that of 6 M aqueous KOH. Anode materials are for example ABx high capacity hydrogen storage alloys comprising Mg where x is from about 0.5 to about 5 and which has a discharge capacity of .gtoreq.400 mAh/g.
GOVERNMENT SUPPORT STATEMENT
 This invention was made with government support under DE-AR0000386 awarded by Advanced Research Projects Agency-Energy under the Robust Affordable Next Generation EV Storage Program (RANGE). The government has certain rights in the invention.