Nitrogen-Doped Mesoporous Carbon Promoted Chemical Adsorption of Sulfur and Fabrication of High-Areal-Capacity Sulfur Cathode with Exceptional Cycling Stability for Lithium-Sulfur Batteries

Lithium-sulfur batteries have attracted increasing attention as next-generation energy storage devices for plug-in hybrid and all-electric vehicles, owing to the extremely high theoretical specific capacity (1672 mA h/g) and energy density (2600 Wh/kg) of sulfur. In addition, sulfur is low-cost, abundantly available, and eco-friendly, making Li-S batteries even more attractive.^1-3

As one important component of sulfur cathodes, the carbon host plays a key role in the electrochemical performance of lithium-sulfur batteries. In this talk, mesoporous nitrogen-doped carbon (MPNC)-sulfur nanocomposite is reported as a novel cathode for advanced Li-S batteries. The nitrogen doping in the MPNC material can effectively promote chemical adsorption between sulfur atoms and oxygen functional groups on the carbon, as verified by X-ray absorption near edge structure spectroscopy, and the mechanism by which nitrogen enables this behavior is further revealed by density functional theory calculations. Based on the advantages of the porous structure and nitrogen doping, the MPNC-sulfur cathodes show excellent cycling stability (95% retention within 100 cycles) at a high current density of 0.7 mAh/cm² with a high sulfur loading (4.2 mg S/cm²) and a sulfur content (70 wt.%). A high areal capacity (~3.3 mAh/cm²) has been demonstrated by using this novel cathode, which is crucial for the practical application of Li-S batteries. We believe that the important role of nitrogen doping promoted chemical adsorption can be extended for development of other high performance carbon-sulfur composite cathodes for Li-S batteries.

Acknowledgements

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under Contract No. DE-EE0005475.

 References

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[3]   A. Manthiram, Y. Fu, Y.-S. Su, Acc. Chem. Res. 2013, 46, 1145.