Highly Dispersed Cobalt Clusters in Nitrogen-Doped Porous Carbon Enable Multiple Effects for High-Performance Li-S Battery

The lithium-sulfur (Li-S) battery is considered a promising candidate for the next generation of energy storage system due to its high specific energy density and low cost of raw materials. However, the practical application of Li-S batteries is severely limited by several weaknesses such as the shuttle effect of polysulfides and the insulation of the electrochemical products of sulfur and Li2S/Li2S2. Here, by doping nitrogen and integrating highly dispersed cobalt catalysts, a porous carbon nanocage derived from glucose adsorbed metal-organic framework is developed as the host for a sulfur cathode. This host structure combines the reported positive effects, including high conductivity, high sulfur loading, effective stress release, fast lithium-ion kinetics, fast interface charge transport, fast redox of Li2Sn, and strong physical/chemical absorption, achieving a long cycle life (86% of capacity retention at 1C within 500 cycles) and high rate performance (600 mAh g(-1) at 5C) for a Li-S battery. By combining experiments and density functional theoretical calculations, it is demonstrated that the well-dispersed cobalt clusters play an important role in greatly improving the diffusion dynamics of lithium, and enhance the absorption and conversion capability of polysulfides in the host structure.