Low-cost H₂/K⁺ hybrid batteries for large-scale energy storage

Rechargeable hydrogen gas batteries are gaining significant attention as a highly reliable electrochemical energy storage technology. However, the high costs of both cathode and anode limit their widespread applications. Here, we demonstrate a low-cost H₂/K⁺ hybrid battery using Fe–Mn-based Prussian white - K_2·74Mn[Fe(CN)₆]_0.90·0.13H₂O (KMF) as cathode and non-noble metal high entropy alloy (NNM-HEA) as anode. It demonstrates a high capacity of 146.1 mAh g⁻¹ at 1 A g⁻¹ with excellent rate performance and stability. Even with a ∼7-fold increase in active loading of the KMF cathode, the capacity of the H₂/K⁺ battery remains as high as 100.5 mAh g⁻¹. Furthermore, a low-cost H₂/K⁺ hybrid battery using our newly developed NNM-HEA based hydrogen catalytic anode is successfully fabricated, which shows an extended capacity with a retention of 90% after 1200 cycles. This work will pave the way for designing low-cost electrode materials for high-performance, large-scale energy storage hydrogen gas batteries.