Accelerated Single Li‐Ion Transport in Solid Electrolytes for Lithium–Sulfur Batteries: Poly(Arylene Ether Sulfone) Grafted with Pyrrolidinium‐Terminated Poly(Ethylene Glycol)

Abstract

Polymeric solid electrolytes have attracted tremendous interest in high‐safety and high‐energy capacity lithium–sulfur (Li─S) batteries. There is, however, still a dilemma to concurrently attain high Li‐ion conductivity and high mechanical strength that effectively suppress the Li‐dendrite growth. Accordingly, a rapidly Li‐ion conducting solid electrolyte is prepared by grafting pyrrolidinium cation (PYR⁺)‐functionalized poly(ethylene glycol) onto the poly(arylene ether sulfone) backbone (PAES–g–2PEGPYR). The PYR⁺ groups effectively immobilize anions of Li‐salts in Li‐conductive PEGPYR domains phase‐separated from PAES matrix to enhance the single‐ion conduction. The tailored PAES–g–2PEGPYR membrane shows a high Li‐ion transference number of 0.601 and superior ionic conductivity of 1.38 mS cm⁻¹ in the flexible solid state with the tensile strength of 1.0 MPa and Young's modulus of 1.5 MPa. Moreover, this PAES–g–2PEGPYR membrane exhibits a high oxidation potential (5.5 V) and high thermal stability up to 200 (C. The Li/PAES–g–2PEGPYR/Li cell stably operates for 1000 h without any short circuit, and the rechargeable Li/PAES–g–2PEGPYR/S cell discharges a capacity of 1004.7 mAh g⁻¹ at C/5 with the excellent rate capability and the prominent cycling performance of 95.3% retention after 200 cycles.