Boosting the Electrochemical Performance of Li-S Batteries with a Dual Polysulfides Confinement Strategy

摘要

Lithium-sulfur (Li-S) batteries have attracted more and more attention because they represent one of the most promising candidates to satisfy emerging energy storage demands. The biggest challenge regarding the application of the Li-S battery is to suppress the polysulfide shuttle while maintaining a high sulfur loading mass. Here, a dual polysulfide confinement strategy is designed by confinement of sulfur in polydopamine-coated MXene nanosheets (denoted as S@Mxe@PDA) that performs as a high-performance cathode for Li-S cells owing to their inherently high underlying metallic conductivity and chemical bonding and strong chemical adsorption to lithium polysulfides (LPs). This dual LPs confinement strategy is supported by the results of density functional theory calculations. It is demonstrated that the S@Mxe@ PDA cathode exhibits outstanding electrochemical properties, including high reversible capacity (1044 mAh g~(-1) after 150 cycles at 0.2 C), superior rate capability (624 mAh g~(-1) at 6 C) and excellent cycling stability (556 mAh g~(-1) after 330 cycles at 0.5 C with 4.4 mg cm~(-2) sulfur loading). This work offers a facile and effective method for boosting Li-S batteries into practical applications.