Free-standing, curled and partially reduced graphene oxide network as sulfur host for high-performance lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have received more and more attention because of higher specific capacity and energy density of sulfur than current lithium-ion batteries. However, the low electrical conductivity of sulfur and its discharge product, and also the high dissolution of polysulfides restrict the Li-S battery practical applications. To improve their performances, in this work, we fabricate a novel free-standing, curled and partially reduced graphene oxide (CPrGO for short) network and combine it with sulfur to form a CPrGO-S composite as a cathode for Li-S battery. With sulfur content of 60 wt%, the free-standing CPrGO-S composite network delievers an initial capacity of 988.9 mAh.g(-1). After 200 cycles, it shows a stable capacity of 841.4 mAh.g(1) at 0.2 C, retaining about 85% of the initial value. The high electrochemical performance demonstrates that the CPrGO-S network has great potential applications in energy storage system. Such improved properties can be ascribed to the unique free-standing and continous CPrGO-S network which has high specific surface area and good electrical conductivity. In addition, oxygen-containing groups on the partially reduced graphene oxide are beneficial to preventing the polysulfides from dissolving into electrolyte and can mitigate the "shuttle effect".