(78b) Rational Design of the Cathode Materials in the Lithium-Sulfur Batteries

Authors: 
Mou, T., University of Oklahoma
Wang, B., University of Oklahoma
Rational design of the sulfur electrode is essential to solve several practical problems in lithium–sulfur batteries. Great progress has been made by using carbon-based nanostructures for physically and chemically confining soluble polysulfide, however, the underlying mechanism remains unclear. Here using density functional theory calculations, we show that the interfacial interaction between Li2S8 – a typical lithium polysulfide formed at the beginning of discharge – and the oxygen/nitrogen modified graphitic surface and edges. Our results indicate that N and O impurities play a significant role in chemically stabilizing lithium polysulfide, which are otherwise soluble, onto the carbon surface. In addition, we find that O and N functional groups can work synergistically by forming the N-C-O complex, which can enhance the interfacial binding. Moreover, we show that, by manipulating the wettability of the cathode surface using oxygen-containing hydrophilic species, adsorption of the polysulfide and electronic conductivity can be controlled to improve the performance.

Acknowledgements: The calculations were performed at NERSC and OU Supercomputing Center for Education and Research (OSCER). We thank support from the U.S. DOE through a DOE/EPSCOR grant (DESC0004600).

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