Cobalt Nanoparticles Decorated “Wire in Tube” Framework as a Multifunctional Sulfur Reservoir

The various designs of sulfur host materials for the lithium–sulfur (Li–S) battery have attracted ever-increasing interest in alleviating the fatal shuttle effect of lithium polysulfide (LiPS) intermediates. Designing host materials for sulfur cathodes needs particular attention in both physical confinement and surface chemistry. Herein, the Co, N codoped "wire in tube" carbon fiber (WIT-Co) is rationally fabricated and serves as the sulfur host. Benefiting from the synergistic effects of excellent LiPS absorption and electrocatalysis capability, the WIT-Co/S cathode reveals a high initial capacity of 1462 mAh g–1 at 0.1 C and stable cycling performance of 650 mAh g–1 at 2.0 C after 400 cycles with a low-capacity decay of 0.021% per cycle. Notably, even with the high sulfur loading of 5.6 mg cm–2 and low electrolyte/sulfur ratio of 5 μL mg–1, the WIT-Co/S electrode still exhibits an excellent areal capacity of 4.8 mAh cm–2 at 0.2 C after 100 cycles. This work provides a superior structure of the sulfur host, which not only accelerates the conversion of LiPSs but also alleviates the shuttle effect, therefore facilitating the practical application of Li–S batteries.