Carbon/Nitrogen Co-Modified Nano-Ni Catalyst Endows a High Energy Density and Low Cost Aqueous Ni-H₂ Gas Battery

Aqueous hydrogen gas (H-2) batteries with high safety and proven long lifespan have shown attractive prospects for large-scale energy storage. However, the development of low-cost and relatively high activity nonprecious metal catalysts for the hydrogen oxidation reaction (HOR) for a hydrogen electrode is the key to solving its cost bottleneck. Here, We have achieved a low-cost and highly active nanonickel hydroxide catalyst through a simple ball-milling method combined with carbon-nitrogen comodification. The experiments indicate that in the presence of carbon modification, nitrogen interacts with carbon to suppress the formation of Ni3N, while trace nitrogen modification on nickel significantly enhances hydroxide activity. The optimized N-Ni/C-4 catalyst exhibits intrinsic activity 11.36 times that of Ni/Ni3N (without C modification) and 17.85 times that of commercial Raney-Ni. Moreover, based on this N-Ni/C-4 catalytic electrode, superior rate performance is demonstrated in an aqueous nickel-hydrogen gas cell compared to commercial Raney-Ni, achieving 300 cycles/1000 h of charge/discharge at 30 mA cm(-2), with no decline in Coulombic efficiency. This 900 mAh N-Ni/C-4-based Ni-H-2 cell achieves an energy density of 165 Wh kg(-1) and is currently reported to be one of the lowest-cost nickel-hydrogen cell. This low-cost, highly active nanonickel catalyst demonstrates significant potential in the conversion and application of hydrogen energy.