Diffusion Mechanism of Lithium Ion through Basal Plane of Layered Graphene
详细信息 查看全文
- 作者：Fei Yao ; Fethullah G眉ne艧 ; Huy Quang Ta ; Seung Mi Lee ; Seung Jin Chae ; Kyeu Yoon Sheem ; Costel Sorin Cojocaru ; Si Shen Xie ; Young Hee Lee
- 刊名：The Journal of the American Chemical Society
- 出版年：2012
- 出版时间：May 23, 2012
- 年：2012
- 卷：134
- 期：20
- 页码：8646-8654
- 全文大小：639K
- 年卷期：v.134,no.20(May 23, 2012)
- ISSN：1520-5126
文摘
Coexistence of both edge plane and basal plane in graphite often hinders the understanding of lithium ion diffusion mechanism. In this report, two types of graphene samples were prepared by chemical vapor deposition (CVD): (i) well-defined basal plane graphene grown on Cu foil and (ii) edge plane-enriched graphene layers grown on Ni film. Electrochemical performance of the graphene electrode can be split into two regimes depending on the number of graphene layers: (i) the corrosion-dominant regime and (ii) the lithiation-dominant regime. Li ion diffusion perpendicular to the basal plane of graphene is facilitated by defects, whereas diffusion parallel to the plane is limited by the steric hindrance that originates from aggregated Li ions adsorbed on the abundant defect sites. The critical layer thickness (lc) to effectively prohibit substrate reaction using CVD-grown graphene layers was predicted to be 6 layers, independent of defect population. Our density functional theory calculations demonstrate that divacancies and higher order defects have reasonable diffusion barrier heights allowing lithium diffusion through the basal plane but neither monovacancies nor Stone-Wales defect.