Electrolyte Engineering for Low-Temperature Aqueous Rechargeable Metal-Ion Batteries: Design Strategies and Perspectives

Aqueous rechargeable metal-ion batteries (ARMBs) represent a promising research field due to their inherent sustainability and safety. However, the practical applications of ARMBs require reliable operation under diverse environmental conditions, particularly at low temperatures. The fundamental challenge for low-temperature ARMBs stems from the solidification of aqueous electrolytes at subzero temperatures, which severely impedes ion transport and electrochemical kinetics. Electrolyte engineering has emerged as the pivotal strategy to overcome this limitation. This review provides a comprehensive summary of recent advances in low-temperature ARMBs, with a specific focus on breakthrough modification strategies for both liquid and hydrogel electrolytes. Furthermore, it compares the effectiveness of various optimization strategies aimed at improving low-temperature performance. Finally, promising future research directions for advancing this rapidly evolving field are outlined. This review offers a foundational understanding and a pragmatic design perspective to guide the development of low-temperature ARMBs for future applications.