Flexible MoNb Bimetallic MXene for High-Performance Lithium-Sulfur Batteries via Separator Modification

en This link goes to a English section zh This link goes to a Chinese section Lithium–sulfur batteries have attracted extensive interest owing to their exceptionally high theoretical energy density and environmental benignity. However, their practical performance remains severely constrained by intrinsic challenges, including the polysulfide shuttle effect and large volume expansion during cycling, which markedly compromise energy efficiency and fall far short of the requirements for commercialization. To address these challenges, we modify a commercial separator (PP) with a dual-transition-metal Mo 2 Nb 2 C 3 MXene, whose surface terminations are precisely regulated via distinct etching strategies, thereby substantially enhancing the electrochemical performance of lithium–sulfur batteries. Compared with cells employing the pristine commercial separator, all PP@Mo 2 Nb 2 C 3 -based cells deliver superior rate performance at a high current density of 3C. Notably, the PP@Mo 2 Nb 2 C 3 -Cl cell retains a high discharge capacity of 589 mAh g −1 after 200 cycles, nearly doubling that of the cell with the commercial PP separator (307 mAh g −1 ). At all tested C-rates, the PP@Mo 2 Nb 2 C 3 -based cells delivered higher discharge capacities than those employing the commercial PP separator. Overall, modification of Celgard 2500 with the dual-transition-metal Mo 2 Nb 2 C 3 MXene effectively suppresses the polysulfide shuttle, enhances sulfur utilization, and substantially prolongs the cycle life of lithium–sulfur batteries. This work provides valuable insights into the rational design and application of MXenes as functional modifiers for advanced lithium–sulfur batteries. 摘要 en This link goes to a English section zh This link goes to a Chinese section 锂硫电池因其高理论能量密度和对环境友好受到广泛关注,但其在工作中产生多硫化物引起的穿梭效应、体积膨胀等问题严重影响电池的效率,远不足以达到商业化的要求。针对这些问题,本文研究了双过渡金属Mo 2 Nb 2 C 3 MXene对商用Celgard 2500进行改性,通过不同的刻蚀方法调控Mo 2 Nb 2 C 3 MXene端基,进而有效提升了锂硫电池的性能。与商用Celgard 2500隔膜相比,所有基于PP@Mo 2 Nb 2 C 3 的电池在3C倍率下均表现出更优异的倍率性能。值得注意的是,PP@Mo 2 Nb 2 C 3 -Cl电池在200次循环后仍保持589 mAh g −1 的高放电比容量,几乎是使用商用Celgard 2500隔膜电池(307 mAh g −1 )的两倍。在不同倍率下,PP@Mo 2 Nb 2 C 3 电池均表现出比使用商用Celgard 2500隔膜电池更高的放电比容量。总体而言,采用双过渡金属Mo 2 Nb 2 C 3 MXene对Celgard 2500隔膜进行改性,能够有效抑制多硫化物穿梭,提高硫利用率,并延长锂硫电池的循环寿命。这项工作为合理设计和应用MXene作为先进锂硫电池的功能改性材料提供了有价值的见解。