A “boxes in fibers” strategy to construct a necklace-like conductive network for the high-rate and high-loading lithium-sulfur batteries
The practical application of the lithium-sulfur batteries has been restricted by the low operating rates and the low areal sulfur loading, resulting from the insulating and dissolving nature of the sulfur and lithium polysulfides. Herein, we propose a “boxes in fibers” strategy and build a hierarchical three-dimensional conductive network, which is based on the necklace-like N-doped carbon nanofibers with threaded hollow carbon nanoboxes and TiC nanoparticles (CNB-TiC@CNF), via a facile electrospinning process. Ideally, a large amount of sulfur could be loaded in the hollow cavities of CNBs and pores of CNFs, employed by physical/chemical active sites, while the interconnected conductive network is beneficial for the fast Li+ diffusion and electronic transfer. Depending on the hierarchical and porous framework, the volume variation of the lithium polysulfides can be further alleviated. The as-constructed CNB-TiC@CNF with enhanced adsorption and conversion ability to polysulfides achieves the high discharge capacity of 1611 mAh g-1 at 0.1 C, high-rate performance up to 10 C for 400 cycles with a decay rate of 0.15% and high sulfur-loading performance with a stable areal capacity of 7.90 mAh cm-2 at 9.2 mg cm-2. Our work provides a novel and efficient strategy for the construction of the three-dimensional hierarchical host as a high-performance cathode for lithium-sulfur batteries.