2D TiN@C sheets derived from MXene as highly efficient polysulfides traps and catalysts for lithium−sulfur batteries

Well known for their high energy density, lithium-sulfur (Li-S) batteries face the problem of rapid capacity degradation caused by the polysulfides (LiPSs) shuttling. By modifying the battery separator with specific materials, the shuttle effect can be effectively alleviated. Herein, two-dimensional (2D) [email protected] sheets obtained by in-situ nitridation of MXene (Ti3C2Tx, T means the termination groups, such as -F, -O, and -OH) are designed as the traps and catalysts for LiPSs in Li-S batteries. [email protected] has strong chemical absorptivity of LiPSs and can promote their conversion to Li2S2/Li2S. By mixing with graphene, which servers as a conductive network and physical barrier, a [email protected]/G separator coating is fabricated via a vacuum filtration method. Based on the carbon black/sulfur (CB/S) cathode and [email protected]/G coated separator, the batteries deliver a surprising initial discharge capacity at 0.1 C (1490.2 mAh g−1) and show a extremely low capacity loss over 600 cycles at 1 C (0.047% per cycle). This work shows new views into the design of separator coating using 2D materials for Li-S batteries with high capacity and stability.