Modulating the solvation structure to enhance amorphous solid electrolyte interface formation for ultra-stable aqueous zinc anode

Abstract

Electrolyte additives are extensively validated effective in mitigating dendrite growth and parasitic reactions in aqueous zinc-ion batteries (AZIBs). Nonetheless, the mechanisms by which additives influence the formation and characteristics of the inorganic solid–electrolyte interphase (SEI) are not yet fully elucidated. Herein, we investigate how Zn(CF₃COO)₂ additives influence solvation structure and elucidate the mechanism by which these additives promote the dual reduction of anions. Through cryo-transmission electron microscopy analysis, we identified the SEI as a highly amorphous ZnS/ZnF₂ phase. This amorphous hybrid SEI demonstrates exceptional stability, mechanical robustness, and high Zn²⁺ conductivity, effectively mitigating parasitic reactions and enhancing Zn plating/stripping reversibility. Even under elevated current densities, the Zn anode exhibits ultra-stable longevity and ultra-high reversibility. This study provides a comprehensive understanding of the intrinsic mechanisms governing solvation structure modulation that lead to the formation of amorphous hybrid SEI, underscoring their efficacy in enhancing the performance and durability of AZIBs.