Organosulfide‐Based Deep Eutectic Electrolyte for Lithium Batteries

Abstract Deep eutectic electrolytes (DEEs) are a new class of electrolytes with unique properties. However, the intermolecular interactions of DEEs are mostly dominated by Li⋅⋅⋅O interactions, limiting the diversity of chemical space and material constituents. Herein, we report a new class of DEEs induced by Li⋅⋅⋅N interactions between 2,2′‐dipyridyl disulfide (DpyDS) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The strong ion‐dipole interaction triggers the deep eutectic phenomenon, thus liberating the Li + from LiTFSI and endowing the DEEs with promising ionic conductivity. These DEEs show admirable intrinsic safety, which cannot be ignited by flame. The DEE at the molar ratio of DpyDS:LiTFSI=4:1 (abbreviated as DEE‐4:1) is electrochemically stable between 2.1 and 4.0 V vs. Li/Li + , and exhibits an ionic conductivity of 1.5×10 −4 S cm −1 at 50 °C. The Li/LiFePO 4 half cell with DEE‐4:1 can provide a reversible capacity of 130 mAh g −1 and Coulombic efficiency above 98 % at 50 °C.