Solid-Liquid-Gas Management for Low-Cost Hydrogen Gas Batteries.

Jiang, Taoli; Wei, Shuyang; Li, Linxiang; Zheng, Kai; Zheng, Xinhua; Park, Sunhyeong; Liu, Shuang; Zhu, Zhengxin et al. · ACS Nano · 2023

basic_science · Level V

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Abstract

Aqueous nickel-hydrogen gas (Ni-H<sub>2</sub>) batteries with excellent durability (>10,000 cycles) are important candidates for grid-scale energy storage but are hampered by the high-cost Pt electrode with limited performance. Herein, we report a low-cost nickel-molybdenum (NiMo) alloy as an efficient bifunctional hydrogen evolution and oxidation reaction (HER/HOR) catalyst for Ni-H<sub>2</sub> batteries in alkaline electrolytes. The NiMo alloy demonstrates a high HOR mass-specific kinetic current of 28.8 mA mg<sup>-1</sup> at 50 mV as well as a low HER overpotential of 45 mV at a current density of 10 mA cm<sup>-2</sup>, which is better than most nonprecious metal catalysts. Furthermore, we apply a solid-liquid-gas management strategy to constitute a conductive, hydrophobic network of NiMo using multiwalled carbon nanotubes (NiMo-hydrophobic MWCNT) in the electrode to accelerate HER/HOR activities for much improved Ni-H<sub>2</sub> battery performance. As a result, Ni-H<sub>2</sub> cells based on the NiMo-hydrophobic MWCNT electrode show a high energy density of 118 Wh kg<sup>-1</sup> and a low cost of only 67.5 $ kWh<sup>-1</sup>. With the low cost, high energy density, excellent durability, and improved energy efficiency, the Ni-H<sub>2</sub> cells show great potential for practical grid-scale energy storage.