Shuttle-inhibited 3D sandwich MXene/SnO2QDs sulfur host for high-performance lithium-sulfur batteries

Herein, sandwich-like Ti 3 C 2 T x MXene/SnO 2 quantum dots composites were synthesized as sulfur host, aiming to alleviate the shuttle effect of polysulfides present in lithium-sulfur batteries. SnO 2 quantum dots (SnO 2 QDs) were introduced into the interlayer of MXene through a simple electrostatic self-assembly method, and the mass fraction of SnO 2 QDs was controlled to construct sandwich MXene/SnO 2 QDs. While SnO 2 QDs effectively alleviating the stacking tendency of MXene, Ti and Sn co-chemisorb polysulfides and the interlayer structure physically confines polysulfides. Significantly, the synergistic effect between MXene with SnO 2 QDs effectively alleviates the shuttle effect of polysulfides and buffers the volume expansion. Meanwhile, with the help of the catalysis of SnO 2 QDs, the liquid-solid reaction kinetics of lithium polysulfides converting to Li 2 S 2 /Li 2 S is accelerated. Electrochemical test results showed that the MXene/SnO 2 QDs/S cathode has a high initial discharge specific capacity (1147.6 mAh g −1 at 0.1 C, while MXene/S is only 615.4 mAh g −1 ), as well as excellent rate performance and cycling stability in Li-S batteries.