Ultrahigh Energy and Power Density in Ni–Zn Aqueous Battery via Superoxide-Activated Three-Electron Transfer

• Efficient activation of Ni electrode employs chronopotentiostatic superoxidation. • Novel superoxide activation mechanism realizes the redox reaction with three-electron transfer (Ni ↔ Ni3+). • As-prepared CPS-Ni||Zn batteries exhibit simultaneously ultrahigh energy and power densities. • The CPS-Ni||Zn microbattery achieves exceptional energy density of 6.88 mWh cm−2 and power density of 339.56 mW cm−2, with stable operation over 10,000 cycles.