Self-support interlayer of dual-intercalation MXene for accelerating polysufides conversion in lithium-sulfur batteries

As one of the most important prerequisites for the practical application of lithium-sulfur (Li-S) batteries, the efficient utilization of active materials still meets the challenge to activate the dissolved polysulfide between the cathode side and the separator. The MXene has metallic centers and rich surface functions to anchor polysulfides, which prevent the shuttle of polysulfides, is widely used in Li-S batteries. However, the self-stacking defects of MXene hinder its chemisorption and catalytic of polysulfides. Here, a plain, scalable additive plug-in scheme was designed for MXene, and the self-supporting film obtained by dual-intercalation supplied an interlayer for Li-S batteries. The macromolecular cetyltrimethylammonium bromide is used to open the layer distance of MXene and expose the catalytic sites, and the nanometer carbon nanotubes are employed as the second insertion to distribute the conductive carbon networks on the MXene nanosheets to physically confine the polysulfides. The functional interlayer carries adsorption and catalytic activities toward polysulfides conversion. Therefore, the Li-S batteries with the interlayer had an initial discharge specific capacity of 1491.8 mA h g-1 at 0.1 C, and an ultra-low-capacity decay of 0.038% per cycle after 500 cycles at 1 C. This work provides an effective strategy on MXene to construct functional intermediate layer for Li-S batteries to hinder the shuttling effect and catalyze the redox conversion of the polysulfides.