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 - K2·74Mn[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.