Electrochemical Properties of MgNi-ZrB Hydrogen Storage Alloys

A series of MgNi-ZrB composites were prepared from MgNi alloy and ZrB alloy by a mechanical alloying (MA) method. The influences of ZrB doping on the structures and the electrochemical properties of MgNi alloy were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), charge-discharge cycles, cyclic voltammetry (CV), Tafel polarization and electrochemical impedance spectroscopy (EIS). The results demonstrate that ZrB doping obviously improves the cycle life of MgNi alloy. The MgNi-ZrB (100:5) composite made from the doped powder ball milled for 15 h exhibits the best electrochemical performances. It shows high discharge capacities of 226 and 209 mAh·g−1 after 20 and 50 cycle, respectively, which are much higher than that of MgNi alloy. Potentiodynamic polarization and EIS tests show that ZrB doping improves the anticorrosion and the electrochemical kinetic properties of MgNi alloy significantly.