Preparation and electrochemical properties of MgNi–MB (M = Co, Ti) composite alloys

Alloys MgNi–MB (M = Co, Ti) were successfully synthesized by means of mechanical alloying (MA). The XRD spectroscopy suggested that the alloys were amorphous. The discharge capacity and cycle life of these alloys were tested, showing that as borides were introduced, the cycling life of the alloys became much better than MgNi alloy. For instance, 10 h composite MgNi–CoB and MgNi–TiB retained 53.2% and 54.1% of the initial capacity after 30 cycles, while the MgNi alloy kept only 23.3%. The exchange impedance spectroscopy and the potentiodynamic polarization curves proved that the electrochemical properties of the composite alloys were improved significantly. MgNi–CoB was used as an example to study the mechanism of electrochemical hydrogen storage.