Atomistic Origins of High Rate Capability and Capacity of N-Doped Graphene for Lithium Storage
Atomistic Origins of High Rate Capability and Capacity of N-Doped Graphene for Lithium Storage
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DOI：
10.1021/nl4038592
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发表时间：
2014-03-01
期刊：
影响因子：
10.8
通讯作者：
Golberg, Dmitri
中科院分区：
文献类型：
--
作者：
Wang, Xi;Weng, Qunhong;Golberg, Dmitri
与纯石墨烯不同，氮掺杂石墨烯（GN）被发现具有高倍率性能和锂存储容量。然而，目前仍缺乏直接的实验证据和对原子尺度存储机制的基本理解，这可能为解释GN超快锂存储特性和高容量的原因提供新的线索。在这里，我们报告了原位透射电子显微镜（TEM）揭示的 GN 能量存储的原子学见解。边缘和基面上的锂化过程直接可视化，观察到吡咯氮“空穴”缺陷和扰动的固体电解质界面构型，并且还研究了三种氮存在形式的电荷转移状态。原位高分辨率TEM实验与理论计算提供了坚实的证据，证明扩大的边缘{0002}间距和表面孔缺陷可以改善表面电容效应，因此高倍率性能和高容量是由于放电过程中边缘的短距离有序化和大量的表面缺陷所致；这种现象以前无法通过标准电子或 X 射线衍射分析来理解。
Distinct from pure graphene, N-doped graphene (GN) has been found to possess high rate capability and capacity for lithium storage. However, there has still been a lack of direct experimental evidence and fundamental understanding of the storage mechanisms at the atomic scale, which may shed a new light on the reasons of the ultrafast lithium storage property and high capacity for GN. Here we report on the atomistic insights of the GN energy storage as revealed by in situ transmission electron microscopy (TEM). The lithiation process on edges and basal planes is directly visualized, the pyrrolic N "hole" defect and the perturbed solid-electrolyte-interface configurations are observed, and charge transfer states for three N-existing forms are also investigated. In situ high-resolution TEM experiments together with theoretical calculations provide a solid evidence that enlarged edge {0002} spacings and surface hole defects result in improved surface capacitive effects and thus high rate capability and the high capacity are owing to short-distance orderings at the edges during discharging and numerous surface defects; the phenomena cannot be understood previously by standard electron or X-ray diffraction analyses.