【摘要】 多硫化物（LiPSs）的穿梭效应和迟缓的氧化还原动力学严重阻碍了锂硫电池的发展。鉴于此，本工作制备了一种负载于掺氮多孔碳（NPC）基体上的超细α-MoC纳米晶材料MoC/NPC,并通过调控碳源和钼源比例优化了碳对MoC纳米晶的限域作用。适当的MoC纳米晶尺寸和NPC含量的MoC/NPC对LiPSs具有最强的吸附作用并能够充分暴露亲硫反应活性位点，从而在有效抑制穿梭效应的同时加速Li₂S沉积形核的反应动力学。最优产物MoC/NPC-12（碳源与钼源的质量比为12）用作硫载体且负载量约1.2 mg·cm^-2时，表现出良好的倍率性能(4C,634.4 mAh·g^-1)、高放电比容量(0.2C,1 203.9 mAh·g^-1)以及优异的循环稳定性（1C倍率下循环400次的每圈容量衰减率仅为0.093%）。当硫负载量增加到3.8 mg·cm^-2时，MoC/NPC-12@S的初始放电面容量为4.7 mAh·cm^-2。本工作为锂硫电池催化剂载体材料的合理设计和优化提供了参考。更多还原

【Abstract】 The shuttle effect of lithium polysulfides（LiPSs） and the sluggish redox kinetics severely hinder the commercial application of lithium-sulfur batteries. The present work made a successful attempt to synthesize an ultrafine α-MoC nanocrystalline material loaded on a nitrogen-doped porous carbon（NPC） substrate, namely MoC/NPC, in which the confinement effect of carbon on MoC nanocrystals could be optimized by controlling the ratio of carbon source to molybdenum source. Appropriate MoC nanocrystal diameter and NPC content were found to lead to the strongest adsorption for LiPSs and full exposure of sulfur-reactive active sites. This not only effectively suppresses the shuttle effect but also accelerates the reaction kinetics of Li₂S deposition and nucleation. The optimum product, MoC/NPC-12, synthesized with a mass ratio of dicyandiamide（C source） to CdMoO₄（Mo source） of 12, demonstrated excellent rate capability(634.4 mAh·g^-1 at 4C), high discharge capacity(1 203.9 mAh·g^-1 at 0.2C), and exceptional cycle stability（a capacity decay rate of only 0.093% per cycle during 400 cycles at 1C） when loaded with～1.2 mg·cm^-2 sulfur. And despite a further increment of sulfur loading to 3.8 mg·cm^-2, an initial areal capacity of MoC/NPC-12@S of 4.7 mAh·cm^-2 could still be achieved. This work provides valuable insights for the rational design and optimization of catalyst host materials in lithium-sulfur batteries.更多还原