High-rate, two-electron-transfer vanadium-hydrogen gas battery

Aqueous rechargeable hydrogen gas batteries have low cost and high safety, which are expected to be used in large-scale energy storage. Here, we design a novel static vanadium-hydrogen gas (V-H) battery by pairing V³⁺/VO₂ ⁺ liquid redox cathode with the hydrogen gas anode. The two-electron reactions between V³⁺ and VO₂ ⁺ in static hydrogen gas batteries is reported for the first time. The V-H battery has a volumetric capacity of 18.1 Ah/L and an energy efficiency of 61 % at a high current density of 500 mA/cm². Moreover, it achieves a high capacity retention of 80 % after 900 cycles and an energy density of 22.6 Wh/L at 300 mA/cm². Finite element simulation proves excellent reversibility of the anode HER/HOR reactions and cathode V³⁺/VO₂ ⁺ redox reactions. This study sheds light on the development of cost-effective, high-energy density, long cycle life, liquid-phase cathode hydrogen batteries for large-scale energy storage applications.