Laser-Induced Ni Foil-Supported NiO@Ni(OH)₂ Hierarchical Structures as Advanced Cathodes for Ultrahigh Performance Nickel–Zinc Batteries

Aqueous Zn-ion batteries have long been considered as a promising substitute for Li-ion batteries due to their low cost, improved safety, and better environmental sustainability. However, the unsatisfactory energy/power density and inferior cycling ability are the two key obstacles of the aqueous nickel–zinc (Ni–Zn) battery, mainly due to the low capacity and serious irreversibility of its Ni-based cathode. To solve these issues, femtosecond laser texturing along with chemical bath deposition was performed to synthesize a 3D hierarchical NiO@Ni(OH)2 composite structure on a nickel foil as an ultrahigh performance cathode for the Ni–Zn battery. Compared with the nickel foil treated only by chemical bath deposition (denoted as NN@NF), the areal capacity of the Ni foil treated by femtosecond laser texturing and the chemical deposition technique (denoted as NN@LTNF) was substantially improved, achieving 0.593 mA h cm–2 at 10 mA cm–2. Moreover, the as-prepared NN@LTNF//Zn battery demonstrated an ideal peak energy density (0.586 mW h cm–2) and power density (86.7 mW cm–2). Particularly, the NN@LTNF//Zn battery could deliver outstanding reversibility and excellent cycling durability (90.2% capacity retention after 1800 cycles). The prominent improvement of electrochemical performance can be attributed to the NiO@Ni(OH)2 composite structure with 3D network morphology and superhydrophilic property, which can facilitate electrolyte penetration and thus ion mobility to active reaction sites. This research may provide promising vistas for laser-processed advanced Ni-based cathodes in ultrahigh electrochemical performance aqueous Ni–Zn batteries.