Advanced Self-Phase-Separating Electrolytes for High-Performance Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries face a critical challenge in synergistically optimizing high-sulfur-loading redox kinetics and suppressing soluble lithium polysulfide (LiPSs) shuttle effects. Herein, we propose a self-phase-separating electrolyte design strategy based on heterogeneous LiPSs dissolution characteristics, using co-solvents of 1,2-dimethoxyethane (DME) and cyclopentyl methyl ether (CPME) to induce spontaneous phase separation during LiPSs dissolution through solvation disparity. The constructed electrolyte system facilitates formation of a strong-solvation region at the cathode to maintain rapid sulfur redox kinetics while establishing a weak-solvation region at the anode to form a stable solid electrolyte interphase (SEI), thereby achieving dual objectives of "kinetics promotion and shuttle suppression" via a spatially partitioned dual-zone synergistic mechanism. This strategy enables steady cycling above 170 cycles of single-layer Li-S pouch cells with ultra-thin Li anodes (50 µm) and high-sulfur-loading cathodes (4.3 mgs cm-2). Moreover, under practical lean-electrolyte conditions (6.2 mgs cm-2 sulfur loading, 50 µm Li, 3 µL mgs -1 electrolyte), a 1.8 Ah multi-layer pouch cell delivers 323 Wh kg-1 energy density with stable cycling above 50 cycles. This work provides an effective solution for resolving the critical trade-off between rapid sulfur conversion kinetics and stable anode interfacial behavior in metal-sulfur batteries.