Electrolyte design strategies and research progress for room-temperature sodium-ion batteries

Electrolyte design or functional development is very effective at promoting the performance of sodium-ion batteries, which are attractive for electrochemical energy storage devices due to abundant sodium resources and low cost. This review discusses recent advances on electrolytes for sodium-ion batteries and comprehensive electrolyte design strategies for various materials systems as well as functional applications. The discussion is divided into three electrolyte types: liquid, solid state, and gel state. Liquid electrolytes are further divided into different solvent types, including organic carbonate ester, ether, ionic liquid, and water. Solid-state electrolytes also contain two types: solid polymer and glass-ceramic composite. The challenges and prospects of electrolytes for sodium-ion batteries are discussed as well. Electrolyte design or functional development is very effective at promoting the performance of sodium-ion batteries, which are attractive for electrochemical energy storage devices due to abundant sodium resources and low cost. The roadmap of the sodium ion batteries based on electrolyte materials was drawn firstly and shows that the electrolyte type decides the electrochemical window and energy density.