Improving the electrochemical performance of a lithium-sulfur battery with a conductive polymer-coated sulfur cathode

Low sulfur utilization, poor cycle life, and the security problems caused by a Li metal anode are the main drawbacks hindering the practical application of lithium-sulfur batteries. Here we report a facile modification of the traditional sulfur cathode to achieve a high capacity and considerably improved cycle life. By coating a commercially-purchased conductive polymer PEDOT:PSS onto the surface of a pristine sulfur electrode, a significant enhancement is achieved in both sulfur utilization and capacity retention. With this strategy, gravimetric energy densities of the cell with the modified S cathode are estimated to 1113 W h kg^-1 based on the total composition of the electrode. The PEDOT:PSS film not only serves as a soft buffer to restrict the polysulfides immigrating to the lithium anode, suppresses mechanical stress and sustains a stable electrode, but also provides more active surfaces to capture and reutilize the polysulfides.