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.