Key issues and modification strategies towards high-performance polymer all-solid-state lithium-sulfur batteries

•Various challenges of solid polymer electrolytes used in lithium-sulfur batteries are summarized.•The electrolyte classification based on matrix materials and ion transport mechanisms are comprehensively reviewed.•Several future research directions of solid polymer electrolyte materials are prospected.•This review provides specific perspectives on the modification and design of lithium salt structures and composite electrolytes. Lithium-sulfur batteries have been recognized as an important development direction for the new energy systems generation because of their advantages of strong energy density, abundant resources, poor price, non-toxicity and harmlessness. The flammability in organic electrolytes have a significant impact on the safety of lithium-sulfur batteries. Replacing liquid electrolytes with solid electrolytes provides a practical solution to the problems. Polymer-based solid electrolytes are widely used in various fields owing to their powerful safety, strong processability, and superb flexibility. However, primary obstacles preventing the commercial use of polymer-based solid electrolytes at the moment are their poor ionic conductivity at ambient temperature, substantial “shuttle effect”, lithium dendrite formation, and interfacial compatibility between electrode and electrolyte. This article discusses the classification of polymer solid-state electrolytes, ion transport mechanisms, and ways to overcome current problems and obstacles by designing and optimizing lithium salt structures, modifying composite electrolytes, and using other modification techniques. The paper concludes by giving an overview on the advancement of polymer solid-state electrolytes and establishing the groundwork for the creation of innovative polymer electrolytes for use in superior performance solid-state lithium-sulfur batteries.