High capacity porous VB2/Ni anodes for VB2/air batteries

Abstract VB 2 has been widely used as an anode material in alkaline air batteries due to its extremely high energy density. However, the currently available VB 2 anodes are unable to deliver the high energy density and only utilized in small capacity cells. Herein, we report a high-capacity porous VB 2 /Ni anode produced by a powder metallurgical route. The effect of sintering temperature on the phase transition, electrical conductivity, electrochemical behavior, and discharge performance of the porous anodes were investigated. The porous VB 2 /Ni anode sintered at 900 °C displays a discharge capacity of 7818 mAh, specific capacity of 3475 mAh/g, coulombic efficiency of 85.6% and specific energy of 2373 mWh/g. The unique porous structure of the VB 2 /Ni anode increases ionic diffusion kinetics while the presence of conductive Ni 2 B or Ni 3 B phases ensures the good electrical conductivity. These nickel borides also enhanced corrosion resistance in the alkaline electrolyte, thus lowering charge-transfer resistance. As a result, the anode sintered at 900 °C performs best. This research sheds light on development of high-capacity VB 2 /air batteries.