Review of regulating Zn²⁺ solvation structures in aqueous zinc-ion batteries

Aqueous zinc-ion batteries, due to their high power density, intrinsic safety, low cost, and environmental benign, have attracted tremendous attentions recently. However, their application is severely plagued by the inferior energy density and short cycling life, which was mainly ascribed to zinc dendrites, and interfacial side reactions, narrow potential window induced by water decomposition, all of which are highly related with the Zn²⁺ solvation structures in the aqueous electrolytes. Therefore, in this review, we comprehensively summarized the recent development of strategies of regulating Zn²⁺ solvation structures, specially, the effect of zinc salts, nonaqueous co-solvents, and functional additives on the Zn²⁺ solvation structures and the corresponding electrochemical performance of aqueous zinc-ion batteries. Moreover, future perspectives focused on the challenges and possible solutions for design and commercialization of aqueous electrolytes with unique solvation structures are provided.