Feng Xin, Li Yu, Zhang Minghao, Li Ying, Gong Yuteng, Liu Mingquan, Bai Ying, Wu Chuan
School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, PR China.
Yangtze Delta Region Academy of Beijing Institute of Technology, Jiaxing 314019, PR China.
ACS Appl Mater Interfaces. 2022 Nov 16;14(45):50992-51000. doi: 10.1021/acsami.2c15694. Epub 2022 Nov 4.
MOF-based materials are a class of efficient precursors for the preparation of heteroatom-doped porous carbon materials that have been widely applied as anode materials for Na-ion batteries. Thereinto, sulfur is often introduced to increase defects and act as an active species to directly react with sodium ions. Although the sulfur introduction and high surface area can synergistically improve capacity and rate capability, the initial Coulombic efficiency (ICE) and electrical conductivity of carbon material are inevitably reduced. Therefore, balancing sodium storage capacity and ICE is still the bottleneck faced by adsorbent carbon materials. Here, sulfur-encapsulated microporous carbon material with nitrogen, sulfur dual-doping (NSPC) is synthesized by postprocessing, achieving the reduced specific surface area by encapsulating sulfur in micropores, and the increased active sites by edge sulfur doping. The synergy between encapsulation and sulfur doping effectively balances specific capacity, rate capability, and ICE. The NSPC material exhibits capacities of 591.5 and 244.2 mAh g at 0.5 and at 10 A g, respectively, and the ICE is as high as 72.3%. Moreover, the effect of nitrogen and sulfur on the improvement of electron/ion diffusion kinetics is resonantly demonstrated by density functional theory calculations. This synergistic preparation method may reveal a feasible thought for fabricating excellent-performance adsorption-type carbon materials for Na-ion batteries.
基于金属有机骨架（MOF）的材料是一类用于制备杂原子掺杂多孔碳材料的高效前驱体，这些多孔碳材料已被广泛用作钠离子电池的负极材料。其中，常引入硫以增加缺陷并作为活性物种直接与钠离子反应。尽管引入硫和高比表面积可以协同提高容量和倍率性能，但碳材料的初始库仑效率（ICE）和电导率不可避免地会降低。因此，平衡储钠容量和ICE仍然是吸附型碳材料面临的瓶颈。在此，通过后处理合成了具有氮、硫双掺杂的硫封装微孔碳材料（NSPC），通过将硫封装在微孔中来降低比表面积，并通过边缘硫掺杂增加活性位点。封装与硫掺杂之间的协同作用有效地平衡了比容量、倍率性能和ICE。NSPC材料在0.5 A g和10 A g时的容量分别为591.5和244.2 mAh g，ICE高达72.3%。此外，密度泛函理论计算共振地证明了氮和硫对改善电子/离子扩散动力学的作用。这种协同制备方法可能为制备高性能钠离子电池吸附型碳材料揭示一种可行的思路。
