Ultrahigh Energy and Power Density in Ni–Zn Aqueous Battery via Superoxide-Activated Three-Electron Transfer
Authors: Yixue Duan, Bolong Li, Kai Yang, Zheng Gong, Xuqiao Peng, Liang He, Derek Ho
Aqueous Ni–Zn microbatteries are safe, reliable and inexpensive but notoriously suffer from inadequate energy and power densities. Herein, we present a novel mechanism of superoxide-activated Ni substrate that realizes the redox reaction featuring three-electron transfers (Ni ↔ Ni3+). The superoxide activates the direct redox reaction between Ni substrate and KNiO2 by lowering the reaction Gibbs free energy, supported by in-situ Raman and density functional theory simulations. The prepared chronopotentiostatic superoxidation-activated Ni (CPS-Ni) electrodes exhibit an ultrahigh capacity of 3.21 mAh cm−2 at the current density of 5 mA cm−2, nearly 8 times that of traditional one-electron processes electrodes. Even under the ultrahigh 200 mA cm−2 current density, the CPS-Ni electrodes show 86.4% capacity retention with a Columbic efficiency of 99.2% after 10,000 cycles. The CPS-Ni||Zn microbattery achieves an exceptional energy density of 6.88 mWh cm−2 and power density of 339.56 mW cm−2. Device demonstration shows that the power source can continuously operate for more than 7 days in powering the sensing and computation intensive practical application of photoplethysmographic waveform monitoring. This work paves the way to the development of multi-electron transfer mechanisms for advanced aqueous Ni–Zn batteries with high capacity and long lifetime.
