Embedding cobalt (II, III) oxide nanoparticles into nitrogen-doped carbon nanotubes-grafted hollow polyhedrons as sulfur hosts for ultralong-life lithium-sulfur batteries.

The sluggish reaction kinetics and unfavorable shuttling effect are regarded as obstacles to the practical application of lithium-sulfur (Li-S) batteries. To resolve these inherent drawbacks, we synthesized novel multifunctional CoO@NHCP/CNT as the cathode materials consisting of carbon nanotubes (CNTs)-grafted N-doped hollow carbon polyhedrons (NHCP) embedded with cobalt (II, III) oxide (CoO) nanoparticles. The results indicate that the NHCP and interconnected CNTs could provide favorable channels for electron/ion transport and physically restrict the diffusion of lithium polysulfides (LiPSs). Furthermore, N doping and in-situ CoO embedding could endow the carbon matrix with strong chemisorption and effective electrocatalytic activity toward LiPSs, thus prominently promoting the sulfur redox reaction. Benefiting from these synergistic effects, the CoO@NHCP/CNT electrode exhibits a high initial capacity of 1322.1 mAh/g at 0.1 C, and a capacity retention of 710.4 mAh/g after 500 cycles at 1 C. Impressively, even at a relatively high current density of 4 C, the CoO@NHCP/CNT electrode achieves a high capacity of 653.4 mAh/g and outstanding long-term cycle stability for 1000 cycles with a low decay rate of 0.035% per cycle. Hence, the design of N-doped CNTs-grafted hollow carbon polyhedrons coupled with transition metal oxides would provide effective promising perspective for developing high-performance Li-S batteries.