MXene/CNT−Co Cathode Host with Synergistic Effect for Enhancing the Performance of Lithium−Sulfur Batteries

Abstract: Lithium−sulfur (Li−S) batteries are regarded as one of the most promising next-generation energy-storage systems owing to their ultrahigh theoretical energy density and the natural abundance of sulfur. However, their practical application is severely hindered by the intrinsically low electrical conductivity of sulfur, sluggish conversion kinetics of lithium polysulfides (LiPSs), and the shuttle effect of LiPSs. To address these challenges, we constructed a three-dimensional (3D) MXene/CNT−Co composite cathode host that integrates strong adsorption with efficient catalysis. The interconnected 3D MXene/CNT conductive framework effectively mitigates the restacking of MXene and establishes continuous electron/ion transport pathways. Meanwhile, the introduced Co provides highly active catalytic sites that markedly accelerate the reversible conversion of LiPSs, enhance chemical adsorption, and suppress polysulfide shuttling. Benefiting from the synergistic regulation of structure and catalysis, the S@MXene/CNT−Co electrode delivers promising electrochemical performance, exhibiting an initial specific capacity of 877.8 mAh g −1 at 1.0 C and retaining 381.2 mAh g −1 after 1000 cycles, corresponding to a capacity retention of 43.4 % and a capacity decay rate of 0.057 % per cycle. In addition, S@MXene/CNT−Co shows excellent rate capability, delivering 443.8 mAh g −1 at 2.0 C, which corresponds to 77.6 % of the initial capacity at 0.2 C. This work provides a viable strategy and rewarding perspective for designing high-performance MXene-based cathode materials for Li−S batteries.