Localized high-concentration electrolytes for rechargeable batteries

Localized high-concentration electrolytes (LHCEs), a novel electrolyte system, are gradually gaining attention in large-scale battery applications owing to their relatively lower viscosity, faster ion transport, and enhanced wettability toward electrodes and separators. Despite several studies on LHCE designs in recent years, research on LHCEs remains in the early stages and lacks the scientific understanding required for practical application. Therefore, it is imperative to elucidate the operating mechanisms of LHCEs and the corresponding electrode-electrolyte interface chemistry. This review systematically summarizes the latest advancements in LHCEs, analyzing their fundamental properties, design principles, advanced functions, and electrochemical behaviors in rechargeable batteries. Meanwhile, various advanced characterization and operando monitoring technologies are discussed to reveal the functionalization mechanisms of LHCEs. Finally, this review proposes insightful conclusions on existing challenges and future research directions of LHCEs, providing valuable guidance for developing advanced electrolytes for rechargeable batteries.