Nickel@Nickel Oxide Core-Shell Electrode with Significantly Boosted Reactivity for Ultrahigh-Energy and Stable Aqueous Ni-Zn Battery

The main bottlenecks of aqueous rechargeable Ni-Zn batteries are their relatively low energy density and poor cycling stability, mainly arising from the low capacity and inferior reversibility of the current Ni-based cathodes. Additionally, the complicated and difficult-to-scale preparation procedures of these cathodes are not promising for large-scale energy storage. Here, a facile and cost-effective ultrasonic-assisted strategy is developed to efficiently activate commercial Ni foam as a robust cathode for a high-energy and stable aqueous rechargeable Ni-Zn battery. 3D Ni@NiO core-shell electrode with remarkably boosted reactivity and an area of 300 cm(2) is readily obtained by this ultrasonic-assisted activation method (denoted as SANF). Benefiting from the in situ formation of electrochemically active NiO and porous 3D structure with a large surface area, the as-fabricated SANF//Zn battery presents ultrahigh capacity (0.422 mA h cm(-2)) and excellent cycling durability (92.5% after 1800 cycles). Moreover, this aqueous rechargeable SANF//Zn battery achieves an impressive energy density of 15.1 mW h cm(-3) (0.754 mW h cm(-2)) and a peak power density of 1392 mW cm(-3), outperforming most reported aqueous rechargeable energy-storage devices. These findings may provide valuable insights into designing large-scale and high-performance 3D electrodes for aqueous rechargeable batteries.