Slimmed Solvation Structure With Dual-Interface Regulation for High-Performance and Safe Lithium-Sulfur Batteries.

Abstract

A crucial step toward widespread electrochemical energy storage is the design of lithium-sulfur batteries (LSBs) that integrate high energy density with robust safety. Realizing practical LSBs demands an electrolyte that possesses high interfacial stability, excellent ion-environment regulation capability, and high electrocatalytic activity. Although current electrolyte technologies have improved the cycling performance of LSBs, preparing electrolytes that simultaneously deliver high energy density, high cycling stability, and high safety remains a significant challenge. Here, we report an electrolyte design strategy aimed at achieving high-performance and high-safety LSBs. This is primarily accomplished by incorporating symmetric ionic plastic crystals into the electrolyte to construct a slimmed solvation structure (Li⁺) regulated by suppression of anion aggregation (S_n ^2- and TFSI^-) during discharge. The electrolyte exhibits high ionic conductivity, low desolvation energy barrier, high electrocatalytic activity, and interfacial stability. This design acts simultaneously on the cathode and anode interfaces, enabling stable and rapid cycling of LSBs, with high energy density (pouch cell: 704 Wh kg^-1) and high stability (average capacity decay rate per cycle of 0.018% over 600 cycles). Our solvation structure model design provides a feasible approach for realizing high-performance and high-safety LSBs.