Sulfone-Based Electrolytes for Highly-Efficient and Stable Lithium Metal Anode

Abstract

Lithium (Li) metal batteries (LMBs) have been regarded as a very promising next-generation energy storage system because of the high theoretical specific capacity, the lowest electrochemical potential and the very low gravimetric density of the Li metal anode. Electrolytes that have high Li metal Coulombic efficiency (CE) and high anodic stability on cathodes play a major role to enable the long-term cycling stability of LMBs. Sulfones are known for their high dielectric constants, low flammability and good oxidation stability, but their application in LMBs is restricted due to their poor compatibility with Li metal anode. Uncontrolled Li platting can result in poor Li CE and induce battery short-circuit. Moreover, their high viscosity and poor wettability towards electrodes and separators are serious issues for practical applications. Here, we demonstrate that nodule-shaped instead of dendritic Li deposition and stable Li plating/stripping cycles can be achieved in concentrated sulfone-based electrolytes with a high CE over 98%. Furthermore, with the addition of selected co-solvents, not only the Li metal CE can be further improved, but also the viscosity and wettability issues are solved, enabling high rate Li||NMC cells cycling at a wide temperature range. As a result, improved cycling performance of Li||NMC cells using sulfone-based electrolytes has been realized.