Solvation Chemistry of Nonaqueous Electrolytes for Rechargeable Magnesium Batteries

Rechargeable magnesium batteries (RMBs) have emerged as a promising candidate for next-generation energy storage due to their intrinsic safety and abundant resource availability. However, the development of ideal electrolytes that enable reversible Mg plating/stripping and ensure electrode compatibility remains a significant bottleneck. Over the past decades, considerable efforts have been devoted to addressing this challenge, highlighting the need for a comprehensive and fundamental understanding of the complex nature of Mg electrolytes. This review presents a comprehensive overview of the advances in nonaqueous Mg electrolytes, with an emphasis on solvation chemistry that governs ion transport, redox kinetics, and solid-electrolyte interphase formation. A systematic analysis of the interactions between ions and solvent molecules, namely active cations, anion receptors, weakly coordinated anions, and solvation structure, is offered to establish a fundamental understanding of structure-function relationships in Mg electrolytes. Furthermore, the key challenges and emerging research trends in Mg electrolytes are summarized. This work underscores the critical role of mastering solvation chemistry in optimizing RMB performance and provides principled guidance for rational, bottom-up Mg electrolyte design.