Porous carbon nanotubes microspheres decorated with strong catalyst cobalt nanoparticles as an effective sulfur host for lithium-sulfur battery

The commercialization of lithium-sulfur (Li–S) battery is largely obstructed by the slow redox kinetics of sulfur cathode and the shuttle effect of polysulfides during its operation, which negatively affect the battery rate capability and cycle life. Herein, a porous CNTs/Co microsphere is synthesized and applied as sulfur host material to boost the electrochemical performance of sulfur cathode. The porous conductive CNTs spherical network can realize a rapid charge and mass transfer via fast conduction of Li+-ions and mitigate the cathode volume expansion in the course of the cycles. Importantly, the Co metal nanoparticles can attain intense chemical adsorption and fast catalytic conversion of polysulfides. Because of the above merits, the high initial discharge specific capacity 1242.5 mAh g−1 was obtained for S-CNTs/Co composite at 0.2C. The capacity decay rate was only 0.066% per cycle at 1C over 300 cycles and the excellent rate performance at up to 3C could also be obtained. Moreover, the S-CNTs/Co composite delivered a high initial areal capacity of 5.7 mAh cm−2 at a high sulfur loading (5.9 mg cm−2), indicating broad perspectives of CNTs/Co as a sulfur host in lithium-sulfur battery. •A porous CNTs/Co microsphere was prepared by spray drying.•CNTs conductive network rendered faster ionic diffusion.•Co nanoparticles impose strong adsorption and catalyzation for polysulfide.•The battery with S-CNTs/Co cathode exhibits excellent cycling performance.