Diffusion Mechanism of Lithium Ion through Basal Plane of Layered Graphene

Fei Yao (1, 2) , Fethullah Gunes (2) , Hui Quang Ta (2) , Seung Mi Lee (3) , Seung Jin Chae (2) , Kyeu Yoon Sheem (4) , Costel Sorin Cojocaru (5) , Si Shen Xie (2) , Young Hee Lee (2)

1 LPICM - Laboratoire de physique des interfaces et des couches minces [Palaiseau]
2 Department of Energy Science
3 Center for Nanocharacterization
4 Samsung SDI Corporate R&D Center
5 NanoMaDe

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.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Fei Yao, Fethullah Gunes, Hui Quang Ta, Seung Mi Lee, Seung Jin Chae, et al.. Diffusion Mechanism of Lithium Ion through Basal Plane of Layered Graphene. Journal of the American Chemical Society, 2012, 134 (20), pp.8646--8654. ⟨10.1021/ja301586m⟩. ⟨hal-00793916⟩