Vanadium hexacyanoferrate as high-performance proton cathode for aqueous hydrogen gas-proton battery

Hydrogen gas-proton batteries (HPBs), utilizing protons as the charge carrier driven by the hydrogen gas anode, demonstrate exceptional rate capability and superior cycling stability in full-cell configurations, and are considered as ideal aqueous proton batteries (APBs) for next-generation energy storage. However, the HPBs still exhibit deficiencies in discharge voltage and specific capacity. Herein, a promising proton cathode, vanadium hexacyanoferrate (VHCF), is developed as a new choice for HPB. Benefiting from the open-framework structure and two redox-active sites (vanadium and iron) of VHCF cathode, the HPB delivers a high specific capacity of 117.8 mAh g⁻¹and a discharge voltage of 1.06 V. At room temperature, superior rate capability (48% of the initial capacity at 3000 C) and stable cycling for 600000 cycles (with 60% capacity retention) are demonstrated, which is the highest value reported for APBs to date. The excellent rate and cycling stability can be maintained at high mass loadings of 25 mg cm⁻² and low-temperature surroundings (−40 ℃). This work is anticipated to motivate the exploration of additional APBs and accelerate advancements in energy storage technology.