A Multifaceted Competitive Zn–Cu Battery Unleashed by Optimizing Charge Protocols

Abstract Rechargeable alkaline Zn–Cu batteries show great potential for energy storage systems due to their high capacity, cost‐effectiveness, and environmental‐friendliness. However, restricted by the severe dissolution upon charging, rapid capacity decline occurs throughout the cycle. Herein, the charging protocol is adjusted to bypass the dissolution stage of high‐valent states, thereby preserving the optimal reaction section of Zn–Cu batteries and greatly improving cycling stability. Additionally, a self‐activation process in the initial stage led to the spontaneous transformation of the original electroplated Cu particles on nickel foam from 10 to 4 mm, enhancing both conductivity and mass transfer, ultimately increasing the utilization of active materials. The battery achieved a discharge capacity of 349.5 mAh g −1 , an ultra‐flat charge–discharge voltage platform, over 92% energy efficiency, a low cost of only $43.25 per kWh, and an exceptionally stable cyclic performance with no noticeable decay over 400 cycles. These 5D improvements position the Cu electrode as a robust candidate for the positive electrode material in the next generation of commercial Zn batteries.