In this study, the substitution of Mg with Zr in La0.7Mg0.3(Ni0.85Co0.15)3.5 was carried out with the purpose of improving the electrochemical performances. The structural and hydrogen storage properties in both gas-solid reaction and the electrochemical system were systematically studied on La0.7(Mg0.3−xZrx)(Ni0.85Co0.15)3.5 (x = 0.05, 0.1, 0.2, 0.3) alloys. Each tested alloy is composed of LaNi3 phase, LaNi5 phase and ZrNi3 phase with different phase abundances. The electrochemical studies indicated that all Zr-substituted anodes possessed a much higher cycling capacity retention than pristine La0.7Mg0.3(Ni0.85Co0.15)3.5. However, the maximum discharge capacity was reduced with the increase of Zr content. The potential-step tests showed that the diffusion of hydrogen atoms inside the anodes was decelerated after the introduction of Zr.
