Realizing high-performance lithium-sulfur batteries via rational design and engineering strategies

Lithium-sulfur batteries (LSBs) have been of paramount interest due to their high specific energy, environmental benignity, and low-cost production as a promising candidate among the next generation of rechargeable batteries. Even they represent one of the most mature battery systems, the high discharging capacity and stable long cycling performance cannot be fully realized, especially under practical conditions, which hamper their entrance to the energy storage market in the near future. Solutions to unsolved issues that arise during the complex and multiphase conversion-type chemistry involved in LSBs are still being researched, including irreversible relocation of polysulfides, slow reaction kinetics, and low reliability of lithium anode. Achieving a scientific understanding of the current challenges toward the individual components in cells and the existing status of research strategies is vitally important to the development of LSBs. In this critical review, we attempt to summarize our current comprehension in this field, analyze and classify possible strategies to address the main concerns in the research on LSBs, and introduce design pathways for the further improvement of LSBs toward practical applications. Advanced methodology toward the synthesis of desirable host materials of the electrode with encapsulation effect via nanostructured design; the tailorable adsorption and catalysis property; chemical confinements function by covalent linking; modification of electronic structure, heteroatom doping, and defects are overviewed and highlighted. Methods for regulating salt anions, solvents, auxiliary additives in electrolytes, and the constructions of interlayers toward deployable separator and anode enabling interfacial protection; the establishment of novel electrode fabrication and functional batteries assembly systems technologies are discussed for the further development of viable LSBs. The strategies and perspectives outlined in this review will provide further research directions and help to achieve the aim of exploring high-performance LSBs technology with high energy density and long cycling stability.