Hollow Co3S4 Nanocubes Interconnected with Carbon Nanotubes as Nanoreactors to Accelerate Polysulfide Conversion for High-Performance Lithium-Sulfur Batteries

Lithium-sulfur batteries (LSBs) with a high energy density of 2600 Wh kg-1 have drawn intensive attention based on the double electron reaction of sulfur. Nevertheless, blocked by the shuttle effect of lithium polysulfides and sluggish sulfur conversion kinetics, LSBs display a small specific capacity and a rapid capacity loss. Herein, we describe a conductive framework and electrocatalyst where numerous carbon nanotubes run through the hollow Co3S4 nanocubes as the sulfur host. The hollow structure can buffer the volume change during the discharge/charge process, while the CNTs link cubes together to facilitate electron transport. The Co3S4 catalyst can not only effectively accelerate the conversion from liquid LiPSs into solid Li2S1/2 but also promote the conversion of Li2S2 into Li2S. Based on the DFT theoretical calculation, the Li-S bond of Li2S2 became longer after interaction with Co3S4, indicating that it is easier to break into Li2S. Thus, the Co3S4/CNTs composite cathode shows a higher initial specific capacity (1252 mAh g-1) than the CNT cathode (928 mAh g-1) at 0.1C. In addition, it also shows a specific capacity of 440 mAh g-1 after 800 cycles with a decay rate of 0.08% per cycle at 1.0C. This work provides a new perspective for improving the sluggish transformation kinetics, which is conducive to the enhancement of sulfur utilization.