Multifunctional MXene/CNT-Zr 3D Composite Cathode for Long Cycling Stability in High-Performance Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries have emerged as one of the most promising rechargeable energy storage systems, owing to sulfur’s high theoretical specific capacity (1675 mAh g -1 ) and the battery’s ultrahigh energy density (2600   Wh   kg -1 ). Nevertheless, their commercialization remains critically hindered by poor cycling durability, primarily stemming from two challenges: the shuttle effect of lithium polysulfides (LiPSs) between electrodes and the substantial volume expansion/contraction of the sulfur cathode during charge-discharge cycles. To address this issue, multifunctional composite material, MXene/CNT-1Zr, was prepared by a hydrothermal method as host material for sulfur in Li-S batteries. The enhancement of the electrical conductivity of sulfur is facilitated by the carbon nanotubes (CNTs), which also disperse and hold MXene to form a 3D framework. The in-situ loaded nano-ZrO 2 by hydrothermal method exhibits robust catalytic activity of the host material, facilitates the host to have a high-intensity chemisorption capacity for polysulfides, which effectively inhibits the shuttling effect of sulfur, thereby improving the cycling stability of batteries. Due to the multifunctional synergistic effect of framework structure, good conductivity, high specific surface area, strong adsorption ability for polysulfides, and strong catalytic activity of ZrO 2 nanoparticles, S@MXene/CNT-1Zr electrode material exhibited excellent cycling stability. The initial discharge capacity of S@MXene/CNT-1Zr at 1.0   C current was 904.8 mAh g -1 when the areal sulfur loading is 2.0   mg   cm -2 , and the residual discharge capacity was 381.1 mAh g -1 after 1000 cycles, with a capacity retention rate of 43.6% and a decay rate of only 0.057% per cycle. The multifunctional MXene/CNT-1Zr composite developed in this study shows potential for use as cathode material in Li-S batteries, offering effective solutions to the challenges encountered by these batteries.