Improved electrochemical performance of Li-S battery with carbon and polymer-modified cathode

In-situ precipitation method is used to synthesize nano-sulfur particles and acetylene black/sulfur (AB/S) binary composite. And then AB/S/polypyrrole (AB/S/PPy) ternary composite is prepared by chemical oxidation polymerization method. AB is an effective sulfur storage substrate, and its chain-like structure provides a good basis for the rapid transmission of lithium ions and electrons. PPy as an outermost coating layer not only alleviates volume expansion but also effectively inhibits the shuttle effect of lithium-sulfur batteries (LSBs) during charge and discharge process. The experimental results demonstrate that the addition of carbon and the conductive polymer significantly contributes to improving the electrochemical performance of AB/S/PPy composite cathode. At a current density of 200 mA g(-1), the initial specific discharge capacity of AB/S/PPy composite cathode is 1090 mAh g(-1), and retains 577 mAh g(-1) after 100 cycles. In comparison, AB/S composite and pure sulfur electrode exhibit poor electrochemical performance. Therefore, all the experimental results indicate that AB/S/PPy ternary composite is a potential cathode material for LSBs.