Research progress on ester-based low-temperature electrolytes for sodium-ion batteries

Abstract

As a potential alternative technology to lithium-ion batteries(LIBs), sodium-ion batteries(SIBs) have seen rapid development in recent years. Because of the wide temperature range characteristics, it is considered to be a viable solution for applications in extremely cold environments such as energy storage at high altitudes, space, and deep-sea exploration. However, at extremely low temperature(LT) (<−40 °C), SIBs exhibit poor performance. As a critical component of the battery, the electrolyte greatly affects the LT performance of SIBs. Currently, both commercial SIBs and LIBs are almost based on ester-based organic solvents as the electrolyte. The optimisation of such electrolytes to enhance the LT performance of SIBs has high practical application value. In this review, we focus on the causes of the LT performance degradation of SIBs at the electrolyte level, and introduce the application of traditional carbonate and carboxylic acid ester organic solvents in LT electrolytes. In addition, an in-depth summary and analysis of the design ideas of LT electrolytes are presented, including low melting point, viscosity, weak solvation structure modulation and electrode/electrolyte interface modulation. Finally, novel electrolytes such as high-entropy electrolytes and ionic liquid electrolytes are introduced, and insights into the optimal design of ester electrolytes are provided, aiming to facilitate the large-scale commercial application of SIBs in LT environments.