Regulating anion chemistry in electrolytes from molecular principles to interphases engineering for high energy batteries

Anion chemistry in electrolytes has recently attracted increasing attention due to its important role in governing solvation structure, interfacial reactions, and the formation of anion-derived electrode-electrolyte interphases. However, it remains challenging to elucidate the influence of anion coordination on the solvation dynamics and its correlation with interfacial reactions, and design principles for constructing anion-modulated solvation structures are still lacking. In this review, the coordination mechanism of anions in electrolyte solvation structures is elaborated in detail, as well as their effects on the electrochemical stability window of electrolytes, transport dynamics of solvation structures, and interfacial chemistry. We summarize universal strategies for regulating the interactions between electrolyte components to achieve anion-modulated solvation, with particular emphasis on salt design and solvent-anion interaction tuning. Furthermore, the influence of anions on the redox potential of solvation structures was correlated with interfacial behavior, while the resulting interphases and interfacial kinetics under anion chemistry are elucidated. Advances in characterization methods and their integration with simulations are also discussed, providing new opportunities for probing the dynamic evolution of anions in real time. By tuning the spotlight on anions, this review offers a unique perspective and theoretical foundation for electrolyte design for next-generation high-energy-density batteries. © Science China Press 2025.