Engineering Hollow Cu₂O@CuSe Core-Shell Structure: Enhancing Zn²⁺ Storage Kinetics for High-Performance Rocking-Chair...

Aqueous zinc-ion batteries (AZIBs) are promising energy storage systems due to their low cost, high safety, and considerable theoretical energy density. However, the use of zinc anodes could lead to dendrite growth, low Zn stripping/plating efficiency, and side reactions, hindering rate performance and cycling stability. To address these issues, a hollow Cu₂O@CuSe core-shell structure was synthesized via a simple and eco-friendly solution method. Benefiting from its unique core-shell structure, the material exhibits high specific capacity (430 mAh g^-1 at 0.1 A g^-1), good rate performance (248 mAh g^-1 at 5.0 A g^-1), and better cycling stability (74.4% retention after 4000 cycles at 1.0 A g^-1). A series of tests and characterizations, including in situ electrochemical impedance spectroscopy (EIS), distribution of relaxation times (DRT) analysis and density functional theory (DFT) calculation, confirmed that the CuSe shell not only enhanced the redox activity at the electrode/electrolyte interface, but also provided structural stability for the Cu₂O core. A rocking-chair battery using Cu₂O@CuSe as the anode and ZnMn₂O₄ as the cathode achieves long-term stable cycling (95.7% retention after 500 cycles at 0.1 A g^-1, 84% retention after 20000 cycles at 2.0 A g^-1), demonstrating a promising strategy for high-performance AZIBs anodes.