Performance and characterization of metal hydride electrodes in nickel/metal hydride batteries

In this paper, the metal hydride electrodes used in nickel/metal hydride batteries have been investigated, especially the surface properties of the electrodes, using cyclic voltammetry, electrochemical impedance spectrum, in situ laser-scanning photo-electrochemical microscopy (PEM) and ex situ scanning tunnelling microscope (STM). Our results indicate clearly that surface treatment has a great effect on the performance of the electrodes, affecting such as initial discharge capacity and capacity maintenance. Some considerations about design of the surface treatment method are described. In addition, cathodic and anodic photocurrents have been observed in the potential regions of hydride formation and hydride oxidation by using PEM techniques. Ex situ STM results showed that some Ni cluster-like compounds are formed on the electrode surface after treatment with hydrofluoric acid.