Electrochemical study of LaGaO 3 as novel electrode material of hydrogen battery (Ni/ MH )

The physico‐chemical performance of the novel anode LaGaO 3 for Ni/MH accumulators was studied using the electrochemical impedance spectroscopy (EIS) method during cycling. The measured EIS data of the perovskite oxide are fitted according to the proposed equivalent circuit representing various processes involved in the mechanism of hydrogenation/dehydrogenation reactions of the oxide. Different kinetic elements such as current density , charge transfer resistance , hydrogen transfer resistance , double layer capacitance , and mass hydrogen diffusion were estimated under cycling. The EIS results relieved that current density of the oxide increases quickly during the activation process and its maximum value is obtained at the second cycle (377.67 mA g −1 ). The degradation of the charge transfer rate of the oxide after activation can be ascribed to the corrosion of the electrode/electrolyte interface. The variation of the Warburg impedance could be attributed to the change in the morphological and the structure of the working electrode over cycling. The EIS analysis relieved that electrochemical behavior of the oxide is controlled by the charge‐transfer rate and the modification of the electrode surface.