Carbon nanotubes modified by Co3O4 nanoparticles as efficient sulfur host for high-performance lithium–sulfur batteries

Lithium–sulfur batteries face the challenge of fast capacity fading and low sulfur utilization owing to the “shuttle effect” caused by the electrolyte-soluble lithium polysulfides. To solve this problem, carbon nanotubes modified by Co3O4 nanoparticles were prepared as the cathode materials for lithium–sulfur batteries. Uniform-sized Co3O4 nanoparticles are highly effective to chemically adsorb the soluble polysulfides to inhibit the “shuttle effect”. Moreover, the effect of Co3O4 content on the final electrochemical performance is also discussed. Co3O4 has strong chemical interaction but a low inherent electrical conductivity. It is necessary to balance the LiPS adsorption capability as well as the electrical conductivity of the composite material, and an excess amount grown on the carbon nanotubes will not lead to further increased electrochemical performance. Finally, compared with unmodified carbon nanotubes, the optimized composite material with decorated Co3O4 delivers improved high-rate and cycling performance. The specific capacity at 0.2 C reaches 821 mAh g−1 and capacity retention of 81.7% can be achieved at 0.5 C after 200 charge and discharge cycles.