Reduced graphene oxide coated porous carbon-sulfur nanofiber as a flexible paper electrode for lithium-sulfur batteriesElectronic supplementary information (ESI) available. See DOI: 10.1039/c7nr02423a

Lithium-sulfur (Li-S) batteries have attracted great attention owing to their excellent electrochemical properties, such as the high discharge voltage of 2.3 V, specific capacity of 1675 mA h g −1 and energy density of 2600 Wh kg −1 . The widely used slurry made electrodes of Li-S batteries are plagued by the serious shuttle effect and insulating nature of sulfur. Herein, a reduced graphene oxide coated porous carbon nanofiber flexible paper (rGO@S-PCNP) was fabricated and directly used as an additive-free cathode for Li-S batteries. The results show that the rGO@S-PCNP is certified to be effective at relieving the shuttle effect and improving the conductivity, thus achieving high electrochemical performance. The rGO@S-PCNP composite with a sulfur content of 58.4 wt% delivers a high discharge capacity of 623.7 mA h g −1 after 200 cycles at 0.1 C (1 C = 1675 mA g −1 ) with the average Coulombic efficiency of 97.1%. The excellent cyclability and high Coulombic efficiency indicate that the as-prepared rGO@S-PCNP composite paper can be a promising cathode for lithium-sulfur batteries, and is envisioned to have great potential in high energy density flexible power devices. This facile strategy brings great significance for large-scale industrial fabrication of flexible lithium-sulfur batteries. A flexible additive-free rGO@S-PCNP cathode for Li-S batteries with excellent electrochemical performance was obtained via a facile strategy.