Hydriding properties of Mg‐3d/M‐type nanocomposites (3d = Cu, Ni; M = C, Ni, Cu, Pd)

Abstract Magnesium‐based hydrogen storage alloys have been also considered to be possible candidates for electrodes in Ni‐MH batteries. In this work, we have studied experimentally the structure and properties of Mg 2 Ni(Cu)/M‐type hydrogen storage nanocomposite materials (M = C, Ni, Pd). These materials were prepared by mechanical alloying (MA) followed by annealing and by ball milling, respectively. In nanocrystalline Mg 2 Cu powder, discharge capacities up to 26 mA h g −1 were measured. It was found that nickel substituting copper in Mg 2 (Cu–Ni) alloy greatly improved the discharge capacity of studied material. In nanocrystalline Mg 2 Ni powder, discharge capacities up to 100 mA h g −1 were measured. Additionally, mechanically coated Mg 2 Ni‐based alloys with graphite, nickel, copper or palladium have effectively reduced the degradation rate of the studied electrode materials. They show substantially enhanced cycle life, at room temperature. Results showed also that the strong modifications of the electronic structure of the nanocrystalline alloys could significantly influence on their hydrogenation properties.