Electrochemical characterization of LaNi5 hydride electrode

Galvanostatic, cyclic voltammetric and linear polarization characteristics of LaNi5 electrode with respect to cycling are presented. Variation in volt ammetric charge-discharge current and potential values observed during cycl ing are discussed. Cyclic voltammetric redox currents are correlated with r espective steps in P-C isotherms of LaNi5 - H-2 system. The stepwise reacti ons taking place at the LaNi5 electrode like in normal gaseous mode of hydr ogenation is established. Values of the exchange current density of LaNi5 e lectrode increases during cycling. Evolved gas analysis establishes the ele ctrochemical hydrogen storage. Evolution of hydrogen from b-hydride phase t akes place at room temperature, while from a-phase, hydrogen evolves at hig her temperatures. Microscopic analysis indicates that microcracks in LaNi5 electrodes appear due to electrochemical cycling.