Metal hydride batteries comprising an electrolyte composition which comprises an aqueous solution comprising potassium hydroxide (KOH) and one or more halide and/or oxyacid salts exhibit reduced degradation of the anode material during operation. The salts are for instance alkali metal salts. Anode materials exhibit for instance <100% of the degradation of the same anode material in the same battery when replacing the electrolyte composition with 30 weight percent (wt %) aqueous KOH and the conductivity of the electrolyte composition is for instance .gtoreq.85% of 30 wt % 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.