Polypyrrole coated g-C3N4/rGO/S composite as sulfur host for high stability lithium-sulfur batteries

Abstract

Lithium-sulfur batteries (LSBs) are next-generation electrochemical power devices. However, the poor electrical conductivity of sulfur and the shuttle effect by mediators generated during charging and discharging remain important issues to be addressed. In this study, to overcome these issues, a sulfur-loaded g-C3N4 and rGO composite was coated with PPy using a polymerization method with pyrrole (g-C3N4/rGO/S@PPy) to fabricate a cathode for high-performance LSBs. g-C3N4/rGO/S@PPy demonstrated a high capacity of 1189 mAh g- 1 and high retention of 91% after 200 cycles. Furthermore, even under a high sulfur loading of 5 mg cm(-2) , g-C3N4/ rGO/S@PPy showed a high areal capacity of 5.5 mAh cm(-2) , comparable to that of commercial lithium-ion batteries. PPy as the conducting polymer coated on g-C3N4/rGO/S can facilitate the electronic conduction in the electrode and suppress the dissolution of Li-polysulfide formed during cycling, exhibiting improved stability in the LSB.