3D Hierarchical CNT-Based Host with High Sulfur Loading for Lithium-Sulfur Batteries

A host material capable of efficiently transporting electrons, uniformly impregnating sulfur and effectively anchoring lithium polysulfide, is the key to realizing high-loading lithium-sulfur batteries. In this paper, we construct a three-dimensional hierarchical host formed by one-dimensional nitrogen-doped carbon nanotubes(NCNTs) grown in situ on both sides of two-dimensional oxides nanosheets. The uniformly grown NCNTs not only provide excellent overall conductivity, but also prevent stacking between two-dimensional nanosheets, providing hierarchical pores for diffusion of molten sulfur, which is beneficial to the uniform impregnating of sulfur. Meanwhile, the two-dimensional oxides nanosheets(NS) and cobalt nanoparticles have a strong chemical affinity with polysulfide, promoting the polysulfides adsorption and redox kinetics. Benefiting from the synergistic effects, Li−S batteries based on Co-NCNTs/NS@S cathode delivers a high discharge capability of 1552 mAh g⁻¹ at 0.1 C with a high sulfur content of 80 %, excellent rate capability of 860 mAh g⁻¹ at 2 C and outstanding cycle life with a low capacity decay rate of 0.04 % per cycle over 550 cycles. Even at high sulfur loading of 4.8 mg cm⁻², the cathode still exhibits an areal capacity of 4.6 mAh cm⁻² after 100 cycles at 0.2 C.