Carbon-encapsulated nickel gas diffusion electrode enabling robust and durable aqueous hydrogen gas battery

Aqueous hydrogen (H2) gas batteries with unmatched lifespan are ideal for grid-scale energy storage, yet their deployment remains limited by the lack of low-cost, efficient, and durable hydrogen electrodes. Here, we report a high-throughput and durable gas diffusion electrode (GDE) based on a simply preparable carbon-coated nickel (Ni@C) catalyst and the design of H2 diffusion channels. By optimizing the carbon layer structure, a balance between the intrinsic activity and stability of the catalyst can be achieved. This Ni@C catalyst exhibits a hydrogen oxidation reaction (HOR) activity of 44 A g−1 as well as remarkable hydrogen evolution reaction (HER) performance. Experimental results and theoretical calculations confirm the electronic interaction between the carbon shell and Ni. In combination with a hydrophobic design, a robust and durable Ni@C-GDE has been fabricated. This electrode achieves a low HOR polarization of only 91 mV at 30 mA cm−2, outperforming Pt/C-GDE (154 mV), and operates stably over 4500 cycles (3200 h) for HOR/HER reversing. Enabled by this electrode, a 10 Ah Ni-H2 battery with an energy density of 156.3 Wh kg−1 and cost of 62.2 $ kWh−1 is demonstrated. This work offers a viable strategy for practical and scalable hydrogen gas batteries.