MgNi alloy and TiNi0.5Mn0.5 alloy were successfully synthesized by a mechanical alloying (MA) approach. The MgNi and TiNi0.5Mn0.5 alloys were mixed to prepare the MgNi-x% TiNi0.5Mn0.5 (x＝10, 30, 50) alloys by MA for 10 h. The XRD results suggested that the alloys have amorphous structures, and TiNi0.5Mn0.5 alloys have been dissolved in the main phase of the MgNi alloys. The discharge capacity and cycle life of the alloys were tested, showing that the cycle life of the alloys being doped became much better than that of the MgNi alloys. Especially, the discharge capacity of MgNi-10% TiNi0.5Mn0.5 composition was 394.46 mAh/g, which was lower than that of the MgNi alloy (443.12 mAh/g), and the discharge capacity was 232.57 mAh/g after 50 cycles with the capacity retention of 59%, potentiodynamic polarization curves showed that anti-corrosion performance of the electrodes became better; cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests showed that the electrode catalytic activity was improved significantly and the H atom diffusion impedance decreased after TiNi0.5Mn0.5 doping.

Key words: Mg-based hydrogen storage alloy, electrochemical property, mechanical alloying, cyclic stability