Effects of doping Fe and Al on microstructure and electrochemical characteristics of Mg-based hydrogen storage alloys

The Mg-based hydrogen storage alloys Mg2Ni, Mg2Ni0.7Fe0.3 and Mg1.7Al0.3Ni were successfully synthesized by a two-step process (sintering and ball milling). The crystal structure and microstructure were examined by X-ray diffraction, Scanning Electron Microscope and Malvern particle size analyzer. New phase appears in the tripe alloys doped with Al and Fe, and the particle size ranges from 3 μm to 5 μm. The electrochemical performance studies indicate that the partial substitution of Al for Mg, and Fe for Ni significantly improve the cycle life, reversibility of hydrogen absorption and desorption. The diffusion process is the control step in the electrode reaction of hydrogen storage alloys.

The Mg-based hydrogen storage alloys Mg2Ni, Mg2Ni0.7Fe0.3 and Mgl.7Alo.3Ni were successfully synthesized by a two-step process （sintering and ball milling）. The crystal structure and microstructure were examined by X-ray diffraction, Scanning Electron Microscope and Malvern particle size analyzer. New phase appears in the tripe alloys doped with A1 and Fe, and the particle size ranges from 3μm to 5 μm. The electrochemical performance studies indicate that the partial substitution of AI for Mg, and Fe for Ni significantly improve the cycle life, reversibility of hydrogen absorption and desorption. The diffusion process is the control step in the electrode reaction of hydrogen storage alloys.