Review of Electrolyte Additives for Secondary Sodium Batteries

As the energy storage sector gains prominence, sodium batteries have garnered attention due to their affordability and the abundance of raw materials. Among the methods aimed at enhancing sodium battery performance, electrolyte additives are notably cost-effective. Despite typically comprising no more than 5% of the components, these additives play a crucial role in improving battery cycle life and overall functionality. This review begins by analyzing the factors propelling the development of sodium batteries and the diverse roles of additives, extensively examines the roles of common functional groups (fluorine(F)-containing, sulfonyl, sulfoxide, phosphate ester, nitrogenous, boron, silyl groups, etc.) in additives. Furthermore, it categorizes the latest functional electrolyte additives into five distinct types. Lastly, the review provides an overview of the potential for designing additives that are both sustainable and efficient. This comprehensive review aims to be a valuable resource for informing the strategic selection and enhancement of electrolyte additives, thereby facilitating future progress in the field. Electrolyte additives are key for better secondary sodium battery performance and durability, revolving around safety and stability. Advanced additives with different functional groups help tackle challenges like expensive salts, unstable electrodes, and isolated functions. Three key aspects for better additives are: compatible functional groups, multifunctionality, and eco-friendly characteristic, vital for next-generation batteries. image