A novel synergistic composite with multi-functional effects for high-performance Li-S batteries

The rechargeable lithium-sulfur battery is regarded as a promising option for electrochemical energy storage systems owing to its high energy density, low cost and environmental friendliness. Further development of the Li-S battery, however, is still impeded by capacity decay and kinetic sluggishness caused by the polysulfide shuttle and electrode/electrolyte interface issues. Herein, a new type of metal-organic-framework-derived sulfur host containing cobalt and N-doped graphitic carbon (Co-N-GC) was synthesized and reported, in which the catalyzing for S redox, entrapping of polysulfides and an ideal electronic matrix were successfully achieved synchronously, leading to a significant improvement in the Li-S performance. The large surface area and uniform dispersion of cobalt nanoparticles within the N-doped graphitic carbon matrix contributed to a distinct enhancement in the specific capacity, rate performance and cycle stability for Li-S batteries. As a result of this multi-functional arrangement, cathodes with a high sulfur loading of 70 wt% could operate at 1C for over 500 cycles with nearly 100% coulombic efficiency and exhibited an outstanding high-rate response of up to 5C, suggesting that the S@Co-N-GC electrode was markedly improved by the proposed strategy, demonstrating its great potential for use in low-cost and high-energy Li-S batteries.