PERFORMANCE AND CHARACTERIZATION OF METAL HYDRIDE ELECTRODES IN NICKEL METAL HYDRIDE BATTERIES

In this paper, the metal hydride electrodes used in nickel/metal hydri de batteries have been investigated, especially the surface properties of the electrodes, using cyclic voltammetry, electrochemical impedanc e spectrum, in situ laser-scanning photo-electrochemical microscopy (P EM) and ex situ scanning tunnelling microscope (STM). Our results indi cate clearly that surface treatment has a great effect on the performa nce of the electrodes, affecting such as initial discharge capacity an d capacity maintenance. Some considerations about design of the surfac e treatment method are described. In addition, cathodic and anodic pho tocurrents have been observed in the potential regions of hydride form ation and hydride oxidation by using PEM techniques. Ex situ STM resul ts showed that some Ni cluster-like compounds are formed on the electr ode surface after treatment with hydrofluoric acid.