Multifunctional Metal Halide Perovskite‐Modified Aqueous Electrolytes for Zinc Metal Batteries

Abstract The performance of Zn metal batteries (ZMBs) is significantly hindered by the poor cycling stability and dendrite growth of Zn metal anodes. Herein, Cs ₂ SnCl ₆ is introduced, a lead‐free metal halide double perovskite, as a multifunctional electrolyte additive to address the challenges of Zn anodes. Utilizing a combination of molecular dynamics simulations, COMSOL simulations, and various characterization techniques, it is demonstrated that Cl ⁻ , Sn ⁴⁺ , and Cs ⁺ ions generated from partial hydrolysis of Cs ₂ SnCl ₆ in the 2 m ZnSO ₄ electrolyte can optimize the electrolyte solvation structures, suppress side reactions, facilitate Zn nucleation process, and modulate Zn deposition behavior. As a result, Zn||Zn symmetric cells with Cs ₂ SnCl ₆ ‐enhanced electrolyte achieve remarkable cycling stability over 5000 h at 1 mA cm ⁻² , while the full cell also shows a capacity retention of 99.96% after 1000 cycles. This work provides insights into electrolyte‐driven interface modulation strategies for next‐generation aqueous ZMBs.