Multi-cavity carbon nanofiber film decorated with Co-Nx doped CNTs for lithium-sulfur batteries with high-areal-capacity

The severe shuttle effect and sluggish redox kinetics are the main challenges in sulfur cathodes, leading to capacity degradation and poor rate performance of lithium-sulfur batteries, especially under high sulfur loading and low electrolyte/sulfur (E/S). Herein, a three-dimensional (3D) multi-cavity carbon nanofiber film decorated with Co-N-x doped carbon nanotubes (Co-NCNTs@CNF) has been designed and endowed with dual functions as the sulfur host and an interlayer simultaneously. The multi-cavity structure of Co-NCNTs@CNF provides enough space for high-loading sulfur and relieves the volume expansion of sulfur. In situ protruded CNTs and CNF form a conductive framework conducive to accelerating the electrons/ions transfer. The macroporous structure caused by the introduction of Co-containing hydrotalcite is beneficial for electrolyte penetration, thereby reducing the E/S. Co-N-x sites can act as high-efficiency adsorbents and catalysts to adsorb polysulfides and catalyze the conversion of polysulfides rapidly. Owing to the synergistic effect, the Co-NCNTs@CNF-0.42-S cathode with an interlayer delivers a high areal capacity of 4.77 mA h cm(-2) at 0.2C after 100 cycles under the sulfur loading of 6.7 mg cm(-2) and E/S = 10 mu L mg(-1). This strategy provides a new insight for preparing sulfur cathode materials that can work at low E/S under high sulfur loading.