A Compact Nanoconfined Sulfur Cathode for High-Performance Lithium-Sulfur Batteries

A high-sulfur-loading cathode is the most essential component for lithium-sulfur batteries to gain considerable energy density for practical applications. The main challenges associated with high-sulfur-loading electrodes are low specific capacity caused by the insulating nature of sulfur and poor stability arising from dissolution of polysulfides into most organic electrolytes. Here, we propose a hierarchically structured sulfur cathode that simultaneously tackles both problems associated with high-sulfur-loading electrodes. Specifically, titanium monoxide hollow nanospheres are packed space efficiently and closely connected by carbon layers into microsized “clusters” as the sulfur host. As a result of this hierarchical structure design, the nanoscale reaction chambers and the microscale conductive networks cooperatively promise high capacities of sulfur at various current densities. During cycling, the titanium monoxide polar layer in every nanocompartment effectively hinders the dissolution of polysulfides, resulting in superior cycling stability for the high-sulfur-loading electrode. The number of mobile phones in the world is forecasted to exceed 5 billion in the next few years, and the marketing of electric vehicles is quickly rising worldwide. Growing along these emerging applications is the demand for long-lasting and cost-effective batteries to power not just smartphones in our hands but also the electric vehicles on the streets. Due to their high capacity and low cost, lithium-sulfur (Li-S) batteries are seen as promising candidates for next-generation electrical energy storage. However, current systems are hampered by low capacity mainly restricted by the insulating nature of S and poor stability due to the dissolution of polysulfides. Here, we propose a hierarchically structured cathode that simultaneously tackles both problems associated with the high-S-loading electrodes. We hope that this work might inspire scientists to develop high-efficiency S cathodes, so that Li-S batteries can be realized in our daily life in the near future. This work proposes a hierarchically structured cathode that simultaneously tackles several problems associated with high-sulfur-loading electrodes for lithium-sulfur batteries. This work overcomes the major limitations associated with other host materials of sulfur, and opens up new prospects for constructing more efficient nanostructures for moderating the diffusion loss of polysulfides and enhancing the reaction kinetics of sulfur. We hope this work will inspire scientists to develop better batteries to satisfy the world demand for energy storage.