High-Entropy Multiple-Anion Aqueous Electrolytes for Long-Life Zn-Metal Anodes.

Abstract

Aqueous zinc-ion batteries (AZIBs) hold great promise for large-scale energy storage applications, however, their practical use is significantly hindered by issues such as zinc dendrite growth and hydrogen evolution. To address these challenges, we propose a high-entropy (HE) electrolyte design strategy that incorporates multiple zinc salts, aimed at enhancing ion kinetics and improving the electrochemical stability of the electrolyte. The interactions between multiple anions and Zn²⁺ increase the complexity of the solvation structure, resulting in smaller ion clusters while maintaining weakly anion-rich solvation structures. This leads to improved ion mobility and the formation of robust interphase layers on the electrode-electrolyte interface. Moreover, the HE electrolyte effectively suppresses hydrogen evolution and corrosion side reactions while facilitating uniform and reversible Zn plating/stripping processes. Impressively, the optimized electrolyte enables dendrite-free Zn plating/stripping for over 3000 h in symmetric cells and achieves a high Coulombic efficiency of 99.5% at 10 mA cm^-2 in asymmetric cells. Inspiringly, full cells paired with Ca-VO₂ cathodes demonstrate excellent performance, retaining 81.5% of the initial capacity over 1800 cycles at 5 A g^-1. These significant findings highlight the potential of this electrolyte design strategy to improve the performance and lifespan of Zn-metal anodes in AZIBs.