Polypyrrole-S-coated MWCNT composites as cathode materials for lithium-sulfur batteries

A composite of MWCNTs@S-PPy with excellent electrical conductivity and good restriction on polysulfide has been prepared for lithium-sulfur batteries. In this composite, sulfur particles confined to polypyrrole (PPy) are uniformly distributed on the surface of carbon nanotubes. The MWCNTs@S-PPy composite with a sulfur content of 48.8 wt% delivers a high initial discharge capacity of 1304.9 mAh g−1 at 0.2 C and remains a stable capacity of 986.3 mAh g−1 after 300 cycles. The significant improvement in the electrochemical performance can be attributed to the core-shell structure supported by the multiwalled carbon nanotubes (MWCNTs) and S-PPy composite, which own excellent electronic conductivity and alleviate the “shuttle effect” of lithium polysulfide. These results suggest that the MWCNTs@S-PPy composite is a promising cathode material for high-performance lithium-sulfur batteries.