Recent advances of hollow-structured sulfur cathodes for lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) have attracted increasing interest due to their high theoretical energy density and low-cost sulfur. Challenges are still faced in the development of sulfur cathodes, due to the insulating properties of sulfur and lithium sulfide, diffusion of soluble polysulfides and slow redox kinetics of electrochemical conversion reactions. Hollow-structured materials with features such as high specific surface area, tunable pore structure, and controllable morphology and composition have shown great potential to be applied in high performance sulfur cathodes for LSBs. To promote further breakthroughs in this amazing field, this review highlights on the recent advances of hollow-structured sulfur cathodes, with an emphasis on polar inorganic/organic materials that exhibit strong interactions with polysulfides, thus suppressing the unfavourable shuttle effect, and/or efficient catalytic activity towards sulfur conversion reactions, thus improving the redox kinetics. Material design principles, experimental methods and the subsequent effects on electrochemical performance are discussed. The remaining challenges and perspectives associated with sulfur cathode design and battery evaluation are also presented.