Carbon nanotubes-intercalated Co-N-C as a robust sulfur host for lithium-sulfur batteries

We design a novel sulfur host composite with carbon nanotubes (CNTs) intercalated to the polyhedrons consisting of metallic cobalt and N-doped carbon derived from zeolite imidazolate framework-67 (Co-N-C/CNTs). As compared with the pristine Co-N-C, the intercalated CNTs can lead to significant enhancements of specific surface area, sulfur loading and electroconductivity, thus pronouncedly improving the overall Li-S battery performance. More specifically, the Co-N-C/CNTs/S cathode delivers an initial discharge capacity of 1440.6 mA h g(-1) at 0.1C while 1104.4 mA h g(-1) for Co-N-C/S. At 1C, the capacity decay rate of Co-N-C/CNTs/S is 0.09% per cycle after 500 cycles with the coulombic efficiency more than 98.2%, while 0.14% per cycle with the coulombic efficiency of 96.4% for Co-N-C/S. Evidently, the interpenetration of CNTs into the sulfur host materials is a simple and effective strategy to promote the Li-S battery performance.