Yang Xinyue, Chen Shang, Gong Wenbin, Meng Xiaodong, Ma Junpeng, Zhang Jie, Zheng Lirong, Abruña Héctor D, Geng Jianxin
Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, 15 North Third Ring East Road, Chaoyang District, Beijing, 100029, China.
School of Physics and Energy, Xuzhou University of Technology, Xuzhou, 221018, China.
Small. 2020 Dec;16(48):e2004950. doi: 10.1002/smll.202004950. Epub 2020 Nov 5.
The reaction kinetics of sulfur cathodes generally control the performance of lithium-sulfur (Li-S) batteries. Here, N-doped porous graphitic carbon with bound VN nanocrystals (3D VN@N-PGC), which is synthesized in one pot by heating a mixture of glucose as C source, urea as N source, and NH VO as V source, is reported to be an superior electrocatalytic cathode host for Li-S batteries. Notably, the VN nanocrystals, strongly bound to the N-PGC network, form via in situ reactions among the thermolytic products of starting materials. The dopant N atoms and bound VN nanocrystals exhibit synergistic electrocatalytic effects to promote the cathode reactions of the Li-S cells. The observed enhancements are supported by density functional theory simulations and by the observation of electrocatalytic N- and V-intermediate species, via X-ray absorption near-edge structure spectroscopy. Li-S cells assembled using 3D VN@N-PGC as cathode host exhibit superior performance in terms of specific capacity (1442 mA h g at 0.1 C), rate capability (641 mA h g at 4 C), and cycle life (466 mA h g after 1700 cycles at 2 C, corresponding to a capacity decay of 0.020% per cycle). The one-pot methodology is facile and scalable and offers a new approach for synthesis of various metal nitride-containing materials for other electrocatalytic applications.
硫正极的反应动力学通常控制着锂硫（Li-S）电池的性能。在此，据报道，通过加热以葡萄糖为碳源、尿素为氮源、NH₄VO₃为钒源的混合物一锅合成的具有结合VN纳米晶体的N掺杂多孔石墨碳（3D VN@N-PGC）是一种用于Li-S电池的优异电催化正极主体。值得注意的是，与N-PGC网络紧密结合的VN纳米晶体通过起始材料的热解产物之间的原位反应形成。掺杂的N原子和结合的VN纳米晶体表现出协同电催化作用，以促进Li-S电池的正极反应。密度泛函理论模拟以及通过X射线吸收近边结构光谱对电催化N和V中间物种的观察支持了所观察到的增强效果。使用3D VN@N-PGC作为正极主体组装的Li-S电池在比容量（0.1 C时为1442 mA h g⁻¹）、倍率性能（4 C时为641 mA h g⁻¹）和循环寿命（2 C下1700次循环后为466 mA h g⁻¹，对应于每循环0.020%的容量衰减）方面表现出优异的性能。这种一锅法简便且可扩展，为合成用于其他电催化应用的各种含金属氮化物的材料提供了一种新方法。
