A novel graphene oxide-wrapped sulfur composites cathode with ultra-high sulfur content for lithium–sulfur battery

Abstract

The numerous drawbacks hindering the practical take-off of the lithium–sulfur technology requires significant breakthrough in designing novel sulfur host. Herein, bipyramidal sulfur/graphene oxide composite cathode with sulfur content of 92% is obtained via a room-temperature bottom-up approach with the aid of polyvinylpyrrolidone. Material characterization reveals the uniform coating of each individual sulfur particle by a thin wall of graphene oxide and residual polyvinylpyrrolidone molecules. The robustness and close proximity of the protective graphene oxide shell not only facilitates electron and ion transportation but also restrains the diffusion of polysulfides through interfacial chemical interaction. As a result, the cathode manifests a high initial reversible capacity of 1301 mAh g−1 at 0.2 C, outstanding capacity retention of 86.4% at 1 C after 115 cycles and long cycle life of 250 cycles with 360.6 mAh g−1 remaining capacity at 2 C. The present work provides an affordable and sustainable approach of confining sulfur at high content which is essential for high-energy density lithium–sulfur battery.