Ligand exchange of Li-ion solvation sheath enables balanced electrolytes

Abstract

An ideal electrolyte for high-energy, wide-temperature, and safe lithium-ion batteries (LIBs) should simultaneously satisfy the stringent requirements of bulk and interfacial/interphasial properties, which are unfortunately often in conflict with each other. No existing electrolyte design can address such a conflict. Here, we introduce an electrolyte additive that decouples the convoluted relationship based on the bulk and interfacial/interphasial chemistry, which provides a methodology for designing balanced electrolytes in LIBs. The dynamic conversion of the lithium-ion solvation structure enforced by non-solvents in the optimum ethyl methyl sulfone-based electrolyte brings excellent interphasial chemistries and fast ion-transport kinetics, which serve as the foundation for the balanced electrochemical properties. Such an electrolyte enables wide-temperature, highly stable LIBs with a high energy density of 275 Wh kg⁻¹ and high power density of 680 W kg^–1 for 3 Ah-pouch cells. This work demonstrates a keen appreciation for interfacial/interphasial chemistry and provides a versatile tool for designing better electrolytes.