Review of carbon materials for advanced lithium-sulfur batteries

Lithium-ion batteries (LIBs) are extensively used in numerous portable devices such as smart-phones and laptops. However, current LIBs based on the conventional intercalation mechanism cannot meet the requirements of the electronics industry and electric vehicles although they are approaching their theoretical capacity. Therefore, it is extremely urgent to seek for systems with higher energy densities. Among various promising candidates, lithium-sulfur (Li-S) batteries with a high theoretical capacity are very attractive. However, the commercial use of Li-S batteries still faces obstacles such as the low electrical conductivity of sulfur and lithium sulfide and the dissolution of polysulfides. The introduction of nanocarbon materials into Li-S batteries sheds light on the efficient utilization of sulfur by improving the conductivity of the composites and restraining the shuttle effect of polysulfides. Here, we give a brief review of recent progress on carbon/sulfur composites, especially carbon nanotube-, graphene-and porous carbon-based hybrids, new insights on the relationships between the structure and the electrochemical performance, and propose some important aspects for the future development of Li-S batteries.