Study on the preparation and electrochemical characteristics of MgNi–CoB alloys

To improve the electrochemical performance of MgNi hydrogen storage electrode in alkaline solution, the cobalt boride powder which was prepared by mechanical alloying (MA) method was introduced. MgNi–CoB composites were prepared also by MA. The XRD patterns show they have amorphous structures. SEM photographs suggest the particle size of the composite is about 2–3 μm. It is found that the cycle stability is improved by adding small amount of CoB. The relationship of the mass ratio of MgNi:CoB and electrochemical properties was also studied. After 50 charge–discharge cycles, the discharge capacity of the MgNi–CoB composite was 29.65% higher than MgNi alloy. The cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and anticorruption test (potentiodynamic polarization) were also carried out. The results show that the cycle stability and the anticorrosion behavior of MgNi alloy in alkaline solution benefit from CoB doping.