Enhanced safety of sulfone-based electrolytes for lithium-ion batteries:broadening electrochemical window and enhancing thermal stability

To meet the demands of high-voltage lithium-ion batteries(LIBs),we develop a novel electrolyte through theoretical calculations and electrochemical characterization.Triphenylphosphine oxide(TPPO)is introduced as a film-forming additive into a sulfone-based electrolyte containing 1 mol L^(−1) lithium difluoro(oxalate)borate.Density functional theory calculations show that TPPO has a lower reduction potential than the sulfone-based solvent.Hence,TPPO should be oxidized before the sulfone-based solvent and form a cathode electrolyte interphase layer on the Li-rich cathode.Our research findings demonstrate that adding 2 wt%TPPO to the sulfone-based electrolyte considerably enhances the ionic conductivity within a range of 20-60℃.In addition,it increases the discharge capacity of LIBs in a range of 2-4.8 V while maintaining excellent rate perfor-mance and cycling stability.Flammability tests and thermal gravimetric analysis results indicate excellent nonflammability and thermal stability of the electrolyte.

Sulfone-based high-voltage electrolytes for high energy density rechargeable lithium batteries:Progress and perspective

Further enhancement in the energy density of rechargeable lithium batteries calls for high-voltage cathode materials and stable anodes,as well as matched high-voltage electrolytes without compromising the overall property of batteries.Sulfone-based electrolytes have aroused great interest in recent years owing to their wide electrochemical window and high safety.However,significant challenges such as the complexity of synthesis,high melting point(typically above room temperature),high viscosity,and their poor compatibility with graphite-based anodes have drastically impeded their practical applications.In this review,recent progress of sulfone solvents in high energy density rechargeable lithium batteries is summarized theoretically and experimentally.More importantly,general improvement methods of sulfone-based electrolytes,such as adding additives and cosolvents,structural modifications of sulfo ne,superconcentrated salt strategy are briefly discussed.We expect that this review provides inspiration for the future developments of sulfone-based high-voltage electrolytes(SHVEs)and their widespread applications in high specific energy lithium batteries.