HYBRID Mg-BASED MATERIALS FOR HYDROGEN STORAGE

The major problem in a future world with renewable energies and less environmental pollution is energy storage Novel nanocomposite hydride materials proposed for anodes in hydride based rechargeable Ni-MHx batteries may successfully solve this problem Generally, these materials can be synthesized by mechanical alloying (MA) of two components a major component having good hydrogen storage properties and a minor component used us surface activator In this work, we have synthesized an amorphous hybrid Mg2Ni-Nix-30%La (x=50, 100, 200%) nanocomposites The Mg2Ni electrode, mechanically alloyed, displayed the maximum discharge capacity (90 mA h g(-1)) at the 1(st) cycle but degraded strongly with cycling The poor cyclic behaviour of Mg2Ni electrodes is attributed to the formation of Mg(OH)(2) on the electrodes, which has been considered to arise from the charge-discharge cycles To avoid the surface oxidation, we have examined the effect of nickel and/or lanthanum addition in Mg2Ni-type material This alloying greatly improved the discharge capacities For example, Mg2Ni vertical bar 100%Ni vertical bar 30%La alloy presents higher electrochemical capacities than amorphous or nanocrystalline Mg2Ni The experimental XPS valence bands measured for studied nanocomposite alloys showed a significant broadening compared to that obtained for the microcrystalline alloys Results showed that the strong modifications of the electronic structure of the nanocrystalline alloys could significantly influence on their hydrogenation properties