Abstract
Metal hydride electrodes have been widely used in alkaline aqueous batteries due to their merits of good comprehensive performance, high safety, and environmental benignity. However, their further development is hindered by poor overcharge resistance and limited cycle stability at elevated temperatures. Herein, we describe the preparation of La0.68Ce0.30-xZr0.02NbxNi4.16Co0.36Mn0.30Al0.38 (x = 0, 0.025, 0.05) metal hydride electrodes with high standard potential, bulk modulus, and hydrogen adsorption energy by doping with Nb. Combined experimental and theoretical results have indicated that Nb occupies B-sites in the AB5 structure and that its presence promotes H* formation and inhibits H2 formation by increasing the overpotential. Nb-doping improves the cycle stability of metal hydride electrodes at 50 °C by imparting resistance to pulverization and corrosion, and significantly improves the overcharge resistance performance by increasing the overpotential. Therefore, such metal hydride electrodes can be expected to display overcharge resistance at elevated temperature when deployed in aqueous batteries.
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