Double-layered hollow carbon sphere with large interlayer space combined with Co-SnS cat. as efficient sulfur hosts for Li-S batteries

Abstract

The low sulfur utilization and the serious shuttle effect of polysulfides severely hamper practical application of Li-S batteries. Herein, sulfur cathodes with the multi-functional structures, featured with double-layered hollow carbon sphere with up to 50 nm interlayer space (DLHC-50) in situ grown Co-SnS catalytic layer is designed and synthesized for lithium sulfur batteries. Co-SnS/DLHC-50 can encapsulate 72% sulfur, higher than 63% for Co-SnS/DLHC-20 due to the large interlayer spaces of DLHC-50. Meanwhile, polysulfides are also effectively restricted via physical entrapment from DLHC-50 as well as chemical binding between Co-SnS and polysulfides. Benefiting from the well-constructed host framework, Co-SnS/DLHC-50 @S shows higher specific capacity/capacity retention of 760.4 mA h g−1/72.9% after 500 cycles at 0.5 C, than that of 546.5 mA h g−1/62.2% and 668.9 mA h g−1/62.2%, for DLHC-50 @S, and Co-SnS/DLHC-20 @S, respectively. In addition, the strategy can be also extended to prepare other metal oxides (sulfides)/DLHC-50 for wide applications. Therefore, this work demonstrates a promising route to combat some bottlenecks such as low sulfur utilization, and the shuttle effect of polysulfides for Li-S batteries.