Self‐Adaptive Cobalt‐Based Prussian Blue Analog Cathode for High‐Performance Aqueous Copper Metal Battery

Abstract Aqueous copper metal batteries have garnered significant attention due to their high reliability and low cost. However, the high electrode potential of the copper metal anode, combined with strong interactions between copper ions and the cathode material, results in low energy density and limited cycle life for these batteries. In this work, a structure‐adaptive cobalt‐based Prussian blue analog (Co‐PBA) cathode and an acidic CuSO 4 electrolyte are utilized to enhance the performance of ACMBs. Adding H 2 SO 4 into the CuSO 4 electrolyte can significantly improve the kinetics and reversibility of Cu deposition and dissolution while preventing the formation of Cu dendrites. Physicochemical and electrochemical characterizations of the cathode indicate that the active material undergoes a self‐adaptive structural transformation from Co‐PBA to a Cu‐substituted Co‐PBA (CuCo‐PBA) when immersed in a CuSO 4 ‐containing electrolyte. The in situ‐formed CuCo‐PBA shows increased operating voltage, enhanced structural stability, and improved Cu‐ion diffusion kinetics. Consequently, the Cu||acidic CuSO 4 ||Co‐PBA battery demonstrates outstanding electrochemical performance, including a high capacity of 86.2 mAh·g −1 at 200 mA g −1 , excellent cycling stability of up to 10 000 cycles with a capacity retention of 69.3%, and a remarkable power density of 4513 W kg −1 at 10 A g −1 , showing promising potential as a next‐generation energy storage solution.