Regulating the 3d-orbital occupancy on Ni sites enables high-rate and durable Ni(OH) cathode for alkaline Zn batteries.

The capacity and cycling stability of β-Ni(OH)-based cathodes in aqueous alkaline Ni-Zn batteries are still unsatisfactory due to their undesirable OH adsorption/desorption dynamics during the electrochemical redox process. To settle this issue, we introduce a new atomic-level strategy to finely modulate the OH adsorption/desorption of β-Ni(OH) through tailoring the 3d-orbital occupancy of Ni center by Co/Cu co-doping (denoted as Co-Cu-Ni(OH)). Both experimental outcomes and density functional theory calculations validate that the co-doping of Co and Cu endows the Ni species in Co-Cu-Ni(OH) with appropriate proportion of the unoccupied 3d-orbital, leading to optimized adsorption/desorption strength of OH. As anticipated, the Co-Cu-Ni(OH) electrode demonstrates superior performance, achieving an areal capacity of 0.83 mAh cm and a gravimetric capacity of 164.3 mAh g at ∼50 mA cm (10 A g). Furthermore, it sustains an impressive capacity of 170.8 mAh g (2.3 mAh cm) at a high mass loading of 13.5 mg cm, alongside a long-term cycling performance over 1000 cycles. The assembled Co-Cu-Ni(OH)//Zn cell is able to provide a peak energy density of 0.98 mWh cm and excellent durability. This work highlights the potential of an orbital engineering strategy in the development of next-generation high-capacity and durable energy storage materials.