Regulating the relationship between Zn²⁺ and water molecules in electrolytes for aqueous zinc-based batteries

Aqueous zinc-based batteries (AZBs) with the advantages of high safety, low cost, and satisfactory energy density are regarded as one of the most promising candidates for future energy storage systems. Rampant dendrite growth and severe side reactions that occur at the Zn anode hinder its further development. Recently, a growing number of studies have demonstrated that side reactions are closely related to the active water molecules belonging to the Zn2+ solvated structure in the electrolyte, and reducing the occurrence of side reactions by regulating the relationship between the above two has proven to be a reliable pathway. Nevertheless, a systematic summary of the intrinsic mechanisms and practical applications of the route is lacking. This review presents a detailed description of the close connection between H2O and side reactions at Zn anodes and gives a comprehensive review of experimental strategies to inhibit side reactions by modulating the relationship between Zn2+ and H2O, including anode interface engineering and electrolyte engineering. In addition, further implementation of the above strategies and the modification means for future Zn anodes are discussed.