Nanostructured electrode materials for Ni-MH x batteries prepared by mechanical alloying

Nanocrystalline TiFe- and Mg₂Ni-type alloys were prepared by mechanical alloying followed by annealing. The structure and electrochemical properties of these materials were studied. The properties of hydrogen host materials can be modified substantially by alloying to obtain the desired storage characteristics. It was found that the respective replacement of Fe in TiFe by Ni and Mn improved not only the discharge capacity but also the cycle life of these electrodes. On the other hand, a partial substitution of Mg by Mn in Mg_2?x M _x Ni alloy leads to an increase in discharge capacity, at room temperature. Furthermore, the effect of the nickel and graphite coating on the structure of the nanocrystalline alloys and the electrodes characteristics were investigated. In Mg₂Ni-type alloy mechanical coating with graphite effectively reduced the degradation rate of the studied electrode materials.