Electrochemical study of LaGaO3 as novel electrode material of hydrogen battery (Ni/MH)

International audienceThe physico-chemical performance of the novel anode LaGaO3 forNi/MH accumulators was studied using the electrochemical impedancespectroscopy (EIS) method during cycling. The measured EIS data ofthe perovskite oxide are fitted according to the proposedequivalent circuit representing various processes involved in themechanism of hydrogenation/dehydrogenation reactions of the oxide.Different kinetic elements such as current density I0, chargetransfer resistance Rct, hydrogen transfer resistance Rht, doublelayer capacitance Cdl, and mass hydrogen diffusion Y0 wereestimated under cycling. The EIS results relieved that currentdensity I0 of the oxide increases quickly during the activationprocess and its maximum value is obtained at the second cycle(377.67 mA g_1). The degradation of the charge transfer rate of theoxide after activation can be ascribed to the corrosion of theelectrode/electrolyteinterface. The variation of the Warburgimpedance Y0 could be attributed to the change in the morphologicaland the structure of the working electrode over cycling. The EISanalysis relieved that electrochemical behavior of the oxide iscontrolled by the charge-transfer rate and the modification of theelectrode surface