Methyl Carbamate‐Lithium Salt Deep Eutectic Electrolyte for Lithium‐Ion Batteries

Deep eutectic electrolytes (DEEs) represent a burgeoning field in electrolytes for energy storage applications. Compared to the more conventionally studied Li-ion electrolyte systems, these electrolytes offer numerous advantages, such as high ion concentration, costs, lower temperature operation, and safety. In this work, the formation of a novel eutectic electrolyte based on lithium salts and methyl carbamate was reported. These DEEs were formed via mixing lithium salts and low-cost methyl carbamate at ratios varying from 1 : 2 to 1 : 5 (mol:mol). The DEE formed from methyl carbamate and lithium hexafluorophosphate (LiPF6) at a 1 : 5 molar ratio generated a 4V stability window and a 25 degrees C conductivity of up to 3.16E(-3) S cm(-1). The DEE formed from methyl carbamate and lithium bis(trifluoromethane)sulfonimide (LiTFSI) at a 1 : 5 molar ratio generated a 3.2 V stability window and a 25 degrees C conductivity of up to 2.87E(-3) S cm(-1). The LiPF6 DEE also demonstrated a discharge capacity of 128 mAh g(-1)after 50 cycles with 93 % discharge capacity retention at moderate cycling rates of 0.5C in a lithium titanate (LTO)/lithium iron phosphate (LFP) full cell. These results demonstrate the potential for methyl carbamate to generate eutectics from lithium salts and offer alternative electrolytes for use in low-temperature Li-ion battery applications.