Non-Flammable Dual-Salt Deep Eutectic Electrolyte for High-Voltage Lithium Metal Battery

The application of high voltage cathode electrode materials is an effective way to increase the energy density of batteries. However, the development and design of a stable electrolyte at high voltages needs to be further addressed. Herein, we developed a non-flammable dual-salt deep eutectic solvent (DES) as a safe electrolyte containing LiTFSI, LiDFOB, and succinonitrile in different molar ratios. This non-flammable DES provides high ionic conductivity (4.23 mS cm(-1)) at 25 degrees C, high Li+ transference number (0.75), and wide electrochemical stability (>5.5 V). When using the designed DES electrolytes in high voltage LiCoO2||Li cells, superior electrochemical performance was achieved at cut-off voltages of 3.0-4.45 V and 3.0-4.6 V, even at a high current density of 2 C. This work offers an in-depth understanding of the critical role of dual-salts in DES and provides an approach to designing safe electrolytes for high voltage LiCoO2||Li cells.

Automated summary

The application of high voltage cathode electrode materials is an effective approach to increase battery energy density. However, the development of stable electrolytes at high voltages needs further attention. In this study, a non-flammable dual-salt deep eutectic solvent (DES) was developed as a safe electrolyte, which showed high ionic conductivity, Li+ transference number, and electrochemical stability. The designed DES electrolytes demonstrated superior electrochemical performance in high voltage LiCoO2||Li cells.