A review on low-concentration electrolytes for rechargeable batteries

Low concentration electrolytes (LCEs) offer various advantages, such as lower cost, better wettability, wider temperature operation, and a greater variety of salt species options, which have inspired considerable research interest in a range of rechargeable batteries. In recent years, there have been notable successes in LCE designs, but LCEs are still in the early stages of development, with insufficient scientific cognition and unsatisfactory electrochemical performance. Therefore, it is essential to deepen our understanding of LCE chemistry and gain more insight into design principles if practical applications of LCEs are to be expected. This review outlines the current knowledge on LCE designs and their applications in different battery systems. The solvation/desolvation behaviors of LCEs and the interfacial structures of the electrodes are discussed, with a focus on structure-function correlations. Critical issues for the application of LCEs are highlighted, and perspectives on potential strategies to accelerate their further development with enhanced functionality are provided. This review aims to inspire new efforts to develop better LCEs for practical applications in rechargeable batteries.