Polymer electrolytes in lithium–sulfur batteries: Design strategies, interfacial dynamics, and performance optimization

This review highlights the major role of polymer electrolytes by addressing the key challenges in lithium-sulfur (Li–S) batteries, including polysulfide dissolution and shuttle effects, interfacial instability between electrodes, and lithium dendrite formation. The recent advances in solid, gel, and composite polymer electrolytes have significantly improved ionic conductivity, mechanical strength, and interfacial compatibility, leading to an enhanced cycling stability and rate capability. The functional group engineering for chemical polysulfide confinement, incorporation of nanofillers for physical trapping, and block copolymer design for structural integrity can effectively mitigate active material loss and stabilize the electrode-electrolyte interfaces. In addition, all-solid-state Li–S systems employing strong and self-healing polymer architectures offer improved safety, flexibility, and electrochemical performance. The emerging approaches are bio-derived polymer systems, in situ polymerization techniques for scalable fabrication, and the integration of advanced characterization with computational modeling. Collectively, these innovations have shown the potential of polymer electrolytes as key enablers for achieving Li–S batteries with high energy densities (>500 Wh kg⁻¹), extended cycle life (>1000 cycles), and strong commercial viability.