Electrochemical hydrogen storage performance of Mg₃GeNi₂ alloy

Mg₃GeNi₂ hydrogen storage electrode alloy was synthesized successfully via mechanical milling followed by sintering, and its electrochemical performance as the negative electrode material in a nickel-metal hydride (Ni-MH) battery was studied for the first time. Then, different amounts of nano-nickel were added to the selected alloy with the pre-milling duration of 60 h to further improve the electrochemical performance. XRD results indicate that partial substitution of Mg by Ge in Mg₂Ni can form a stable new phase of Mg₃GeNi₂ with excellent cycle stability. Nano-Ni addition can increase dramatically the discharge capacity and electrochemical kinetics of the alloy, which is attributed to the good electrocatalytic capability of the nano-Ni. The Mg₃GeNi₂-5 wt.% nano-Ni sample shows the optimum overall properties with the best electrochemical kinetics and the highest discharge capacity.