Characterization Techniques for Probing the Electrolyte Solvation Structures of Aqueous Zinc Metal Batteries

While aqueous zinc metal batteries (AZMBs) have shown great promise for large-scale energy storage, a series of interfacial side reactions derived from the decomposition of active water molecules in the Zn²⁺ solvation structures seriously hinder the practical application of AZMBs. Recently, regulating the solvation structures of Zn²⁺ in electrolytes has been proven to be effective in alleviating the interfacial side reactions. Advanced characterization techniques to probe the solvation structures of electrolytes provide powerful tools for comprehensively understanding the underlying relationship between the solvation structures of electrolytes and the performance of AZMBs. Although significant processes have been achieved in electrolyte engineering and mechanistic understanding of the solvation structures has been preliminarily established, systematic summary of the characterization techniques for solvation structures is still absent. Considering the importance of the solvation structures in electrolyte engineering, a comprehensive review of this topic is necessary. In this review article, the advantages and application scope of the ever-used characterization techniques in studying the solvation structures are introduced and the remaining challenges and the potential opportunities in the future are discussed.