Effect of organic additives on electrochemical properties of Li anode in room temperature ionic liquid

Li metal rechargeable batteries have attracted much attention as a candidate for post-Li-ion batteries with higher power voltage and higher energy density. The application of room temperature ionic liquids (RTILs) to the electrolyte instead of nonaqueous electrolytes has been studied with the aim of improvement of the film property on the Li metal/electrolyte interface in order to put the Li metal rechargeable batteries into practice. In this study, the behaviors of Li plating and plating-stripping cycle property were investigated with organic additives [vinylene carbonate (VC) or ethylene sulfite (ES)] added to an RTIL (PP13[TFSA]). A more circular shape of deposit is obtained just after first plating when the organic additives are used, indicating that the organic additives suppress the local growth of Li deposition. Better cycling property and reproducibility are obtained when the organic additives are used, which is consistent with the result after first plating. Therefore, using additives in combination with RTIL-based electrolytes is advantageous.