The electrochemical performance of AB3-type hydrogen storage alloy as anode material for the nickel metal hydride accumulators

摘要

For the purpose of lowering the cost of metal hydride electrode, the La of LaY2Ni9 electrode was replaced by Ce. The electrochemical performances of the CeY2Ni9 negative electrode, at a room and different temperatures, were compared with the parent alloy LaY2Ni9. At room temperature during a long cycling, the evolution of the electrochemical capacity-the diffusivity indicator ()-the exchange current density, and the equilibrium potential were determined. At different temperatures, the electrochemical characterization of this alloy allowed the estimation of the enthalpy, the entropy, and the activation energy of the hydride formation. The evolution of the high-rate dischargeability was also evaluated at different temperatures. Compared with the parent LaY2Ni9 alloy, CeY2Ni9 exhibits an easy activation and good reaction reversibility. This alloy also conserves a good lifetime during a long-term cycling. A lower activation energy determined for this alloy corresponds to an easy absorption of hydrogen into this new alloy.