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A brief survey is given of the various classes of metal alloys and compounds that are suitable for hydrogen-storage and energy-conversion applications. Comparisons are made of relevant properties including hydrogen absorption and desorption pressures, total and reversible hydrogen-storage capacity, reaction-rate kinetics, initial activation requirements, susceptibility to contamination, and durability during long-term thermal cycling. Selected applications are hydrogen storage as a fuel, gas separation and purification, thermal switches, and sorption cryocoolers.

Electrochemical studies were performed on LaNi,Sn, with 0 x 0.5. We measured the effect of the Sn substituent on the kinetics of charge-transfer and diffusion during hydrogen absorption and desorption, and the cyclic lifetimes of LaNi,Sn, electrodes in 250 mAh laboratory test cells. We report beneficial effects of making small substitutions of Sn for Ni in LaNi, on the performance of the metal hydride alloy anode in terms of cyclic lifetime, capacity, and kinetics. The optimal concentration of Sn in LaNi5_Sn alloys for negative electrodes in alkaline rechargeable secondary cells was found to lie in the range 0.25 x 0.3.

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