Electrochemical characterization of LaNi5 hydride electrode

Galvanostatic, cyclic voltammetric and linear polarization characteristics of LaNi5 electrode with respect to cycling are presented. Variation in voltammetric charge-discharge current and potential values observed during cycling are discussed. Cyclic voltammetric redox currents are correlated with respective steps in P-C isotherms of LaNi5 - H-2 system. The stepwise reactions taking place at the LaNi5 electrode like in normal gaseous mode of hydrogenation is established. Values of the exchange current density of LaNi5 electrode increases during cycling. Evolved gas analysis establishes the electrochemical hydrogen storage. Evolution of hydrogen from b-hydride phase takes place at room temperature, while from a-phase, hydrogen evolves at higher temperatures. Microscopic analysis indicates that microcracks in LaNi5 electrodes appear due to electrochemical cycling.