Xing Yi, Yang Yong, Chen Renjie, Luo Mingchuan, Chen Nan, Ye Yusheng, Qian Ji, Li Li, Wu Feng, Guo Shaojun
Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing, 100871, China.
School of Materials Science & Engineering, Beijing Institute of Technology, Beijing, 100081, China.
Small. 2018 May;14(19):e1704366. doi: 10.1002/smll.201704366. Epub 2018 Apr 14.
A highly efficient oxygen electrode is indispensable for achieving high-performance aprotic lithium-O batteries. Herein, it is demonstrated that strongly coupled carbon nanosheets/molybdenum carbide (α-MoC ) nanocluster hierarchical hybrid hollow spheres (denoted as MoC /HSC) can work well as cathode for boosting the performance of lithium-O batteries. The important feature of MoC /HSC is that the α-MoC nanoclusters, uniformly incorporated into carbon nanosheets, can not only effectively prevent the nanoclusters from agglomeration, but also help enhance the interaction between the nanoclusters and the conductive substrate during the charge and discharge process. As a consequence, the MoC /HSC shows significantly improved electrocatalytic performance in an aprotic Li-O battery with greatly reduced charge and discharge overpotentials and long cycle stability. The ex situ scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy studies reveal that the mechanism for the high-performance Li-O battery using MoC /HSC as cathode is that the incorporated molybdenum carbide nanoclusters can make oxygen reduction on their surfaces easy, and finally form amorphous film-like Li-deficient Li O with the ability to decompose at a low potential. To the best of knowledge, the MoC /HSC of this paper is among the best cathode materials for lithium-O batteries reported to date.
对于实现高性能非水锂氧电池而言，高效的氧电极必不可少。在此，研究表明强耦合碳纳米片/碳化钼（α-MoC）纳米团簇分级混合空心球（记为MoC /HSC）作为阴极可有效提升锂氧电池的性能。MoC /HSC的重要特性在于，均匀掺入碳纳米片中的α-MoC纳米团簇不仅能有效防止纳米团簇团聚，还有助于增强纳米团簇与导电基底在充放电过程中的相互作用。因此，MoC /HSC在非水锂氧电池中展现出显著提升的电催化性能，充放电过电位大幅降低，且具有长循环稳定性。非原位扫描电子显微镜、X射线衍射和X射线光电子能谱研究表明，以MoC /HSC作为阴极的高性能锂氧电池的机理在于，掺入的碳化钼纳米团簇可使氧在其表面易于还原，并最终形成具有在低电位下分解能力的非晶膜状缺锂Li O。据了解，本文中的MoC /HSC是迄今为止报道的锂氧电池最佳阴极材料之一。
