Mesoporous Co–N–C composite as a sulfur host for high-capacity and long-life lithium–sulfur batteries

Abstract

Cobalt–nitrogen-doped mesoporous carbon (Co–N–C) is synthesized as a host for lithium–sulfur batteries. With the Co–N–C composite as a sulfur host, the initial capacity of lithium–sulfur batteries is as high as 1290.8 mA h g−1 at 0.2 C, and Li–S batteries still exhibit good cycling stability and high capacity with a retained capacity of 795.7 mA h g−1 and a nearly 100% coulombic efficiency after 300 cycles. The good performance of Li–S batteries can be attributed to a higher specific surface area and pore volume of the carbon matrix and good chemical affinity of Co and N elements toward polysulfides. It is found that Co–N–C composite can effectively adsorb lithium polysulfide by physical, chemical adsorption and well inhibit the shuttle effect. In addition, Co–N–C composite which act as a catalyst can also significantly promote the conversion of polysulfide, accelerate the kinetics, thereby improving the performance of Li–S batteries.