Advanced Self‐Phase‐Separating Electrolytes for High‐Performance Lithium‐Sulfur Batteries

Abstract

Abstract 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 mg s cm −2 ). Moreover, under practical lean‐electrolyte conditions (6.2 mg s cm −2 sulfur loading, 50 µm Li, 3 µL mg s −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.