Advances in Sodium Ion Batteries Based on Mixed Electrolytes of ILs and Organic Solvents

Sodium-ion batteries (SIBs) represent a topic of extreme interest in the research field, especially because the materials used are cheaper than those in lithium-ion batteries (LIBs). In SIBs, the choice of cathodes and electrolytes is very important because they will affect the energy density, cycling stability, and safety of the battery. This work focuses on the prospect of hybrid electrolyte cells that incorporate ionic liquids (ILs) into organic liquids in order to improve the safety and performance of SIBs. Organic solutes make ionic conductivity higher due to larger IL electrochemical windows, good thermal stability and low volatility. They have some issues like flammability, dissolution, and transport limitations, but these aspects could be solved by using hybrid electrolyte systems. In this study, we investigate the effect of using different salts and solvents on the characteristics of the SIBs. We analyze ionic conductivity, electrochemical stability, and the development of stable solid electrolyte interphase (SEI) in the SIBs by using hybrid electrolytes. Additionally, we demonstrate that the addition of ILs to organic electrolytes can improve their thermal stability, so as a result, the safety and lifecycle of the battery will be increased. In conclusion, this research shows how hybrid electrolytes could have great potential for SIB battery technology in high-performance and large-scale energy storage applications.