Self‐Supported Cu Electrode as the Cathode for Hybrid Zn‐Air/Cu Batteries Achieving Long‐Term Operation Under Oxygen‐Free Condition

ABSTRACT The integration of Zn‐air batteries with Zn‐metal batteries enables the efficient realization of hybrid Zn‐based batteries with synergistic high energy and power density. In this hybrid system, the reduction potential of CuO in the Zn‐Cu battery is lower than the oxygen reduction reaction (ORR), thus allowing CuO to replace the ORR and enable discharging under oxygen‐free conditions. Herein, carbon nanotubes are deposited onto copper foam, followed by one‐step calcination process to fabricate self‐supported electrode CuO x @CNTs/CF for hybrid Zn‐air/Cu batteries. The hybrid Zn‐air/Cu batteries deliver the peak power density of 117.5 mW cm −2 and specific capacity of 792.6 mAh g −1 , with a stable cycling life of 800 h. More importantly, the self‐supported electrode enables stable operation for up to 340 h in oxygen‐free environments. Furthermore, the introduction of NiFe‐based active species to construct hybrid Zn‐air/Cu/Ni batteries boosts the peak power density to an excellent 458.4 mW cm −2 . The hybrid batteries exhibit stable cycling life for 1200 h under oxygen‐rich conditions and 390 h in oxygen‐free environments, respectively. This work provides profound insights into the rational design, development and practical applications of hybrid Zn‐based batteries for future energy storage systems.