High-performance three-dimensional flower-like CoS/MWCNT composite host for Li–S batteries

Although lithium–sulfur batteries are promising replacements for conventional lithium-ion batteries, their commercial applications have been limited due to issues such as polysulfide dissolution, volume variation, and low conductivity. To overcome these problems, we designed and hydrothermally synthesized a flower-like three-dimensional CoS/multiwall carbon nanotube (MWCNT) composite as the sulfur host material. The CoS and MWCNTs were tightly joined by chemical bonds to form a stable composite structure. The polar and catalytic CoS can promote the redox process and reduce the dissolution of polysulfides, while the flexible carbon nanotubes can buffer the expansion/shrinkage of the electrode during charging and discharging. CoS/MWCNT-S displays an excellent specific capacity (1120 mAh g −1 , 0.1 C) and high capacity retention after 200 cycles (78%, 0.5 C). Graphic abstract