Achieving multiplexed functionality in a hierarchical MXene-based sulfur host for high-rate, high-loading lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries hold their promise in high energy-density, low-cost energy storage. However, the areal sulfur loading and rate performance in most Li-S batteries do not suffice practical applications due to severe polysulfides shuttling and sluggish reaction kinetics. Here, we report a novel sulfur host comprising planted carbon nanotubes with embedded cobalt on a nitrogen doped hollow MXene scaffold. In this hierarchical structure, the macropores in the hollow scaffold facilitate mass transports and accommodate volumetric changes upon electrochemical lithiation/delithiation, while the cobalt, supported by the conductive carbon nanotube, accelerates polysulfides and Li2S conversion kinetics. At last, the nitrogen dopants enhance the chemisorption of sulfur species on MXene. The above multiplexed functionality enables 840 stable cycles with high capacity 900 mAh g−1 at 2.5 mg cm−2 S-loading and 1C. Even at a sulfur loading of 6 mg cm−2, we can still achieve 170 cycles with a capacity retention 85.8%.