Ionic Liquids Electrolytes for High Performance Sodium Batteries—Chemistry, Composition, and Interfaces

ABSTRACT Novel energy storage and energy generation technologies have been extensively supported by taking advantage of the unique properties of ionic liquids (ILs). In particular, the low volatility, high ionic conductivity, and large chemical and electrochemical stability of some ionic liquid chemistries have been key in the development of high‐performance electrolytes for electrochemical devices including sodium batteries. Recently, exploration has turned to modifications in the ionic liquid cation chemistry, as well as the sodium salt concentration, demonstrating significant influence on the anode cycling performance (both metal sodium and hard carbon), while the initial cycling protocols also have a marked effect on cycling stability. While the beneficial properties of ILs in energy storage applications have been well demonstrated, there is still a great deal to learn about their interactions both in the bulk and at electrode interfaces to facilitate further improvements in their chemical design. Future work to advance next‐generation sodium battery technologies should focus on the design and synthesis of new IL cations and anions with structural features promoting high sodium ion transport through improved coordination structures, as well as improved understanding of the interface interactions that contribute to improved solid electrolyte interphases solid–electrolyte interphase and uniform sodium plating.