A novel hafnium boride catalyst for vanadium redox flow battery

Vanadium redox flow batteries have the advantages of long life, flexible design, safety, and reliability, so they have broad development prospects in the field of energy storage. Borides are extensively used in electrochemistry due to their excellent electrical conductivity. In this program, HfB 2 was used as catalyst for the V 3+ /V 2+ pair. The catalytic effect was verified by electrochemical impedance spectroscopy and cyclic voltammetry. The result shows that the cell using HfB 2 as negative catalyst can exhibit excellent rate capability when the current density is 50 ~ 125 mA cm −2 . At 125 mA cm −2 , the discharge capacity of the modified cell is 68.7 mA h, which is much higher than pristine cell (22.8 mA h). And the energy efficiency of pristine cells is 11.2% lower than that of modified cells. These consequences suggest that HfB 2 is a catalyst with promising prospects to enhance electrochemical activity of V 3+ /V 2+ redox reaction in VRFB.