Two-dimensional sandwich-like MXene–conductive polymer nanocomposite with in-plane cylindrical mesopores for long cycling lithium-sulfur batteries

Abstract

Li-S batteries have received much attention due to their high energy density, low cost and environmental friendliness. However, the poor conductivity of sulfur and the ‘shuttle effect’ of polysulfides still impede their practical applications. In this study, thin layered MXene nanosheets sandwiched by conductive poly(m-phenylenediamine) with in-plane cylindrical mesochannels (mPmPD/MXene) are constructed as sulfur hosts for the cathode materials of Li–S batteries. The polar active sites on MXene and mesoporous conductive PmPD polymers synergistically alleviate the polysulfide shuttling through chemisorption and physical confinement; the high metallic conductivity of MXene and conductive PmPD ensure the transport of electrons and promote the redox kinetics; the in-plane cylindrical mesochannels on mPmPD/MXene provide hosting space for high sulfur loading (∼71 wt%) and facilitate smooth electrolyte transport in the internal space of the cathode. Profiting from these advantages, the Li–S battery based on the mPmPD/MXene cathode exhibits a capacity decay of 0.0593% after 800 cycles at 1 C (53% capacity retention). The optimized battery shows stable cycling performance even at high sulfur loading (6.8 mg cm−2) with 5.6 mAh cm−2 capacity remained after 60 cycles at 0.1 C. This study provides insights for the rational design of 2D heterostructures with in-plane mesochannels for high-performance Li-S batteries.