Modulating electrolyte solvation structure and ion dynamics for thermotolerant Li–S batteries

Traditional electrolytes impose tremendous limitation on the effective operation of lithium–sulfur (Li–S) batteries at elevated temperatures due to insufficient thermal stability and aggravated side reactions, wherein battery failure mechanism and electrolyte design principle remain elusive. Herein, we developed a varied-temperature multimodal nuclear magnetic resonance (VT-mNMR) methodology to elucidate temperature-dependent electrolyte solvation structure and ion dynamics, whereby a thermotolerant bistratal solvation structure electrolyte (BSSE) was formulated to concurrently maintain compact inner solvation sheath and restrict polysulfide shuttling at high temperatures. Cryogenic transmission electron microscopy combined with X-ray photoelectron spectroscopy depth profiling discloses rich inorganic components in the inner layer of solid electrolyte interface. Consequently, Li–S batteries with BSSE can sustain stable operation with a high capacity retention of 90 % at 60 °C, which also harvest a stable cycling performance under a wide temperature range within 20–80 °C. Our study provides a reliable toolbox for studying liquid electrolyte chemistry in Li–S batteries and beyond, which opens a new avenue for advancing extreme-temperature electrolyte design.