In-plane staging in lithium-ion intercalation of bilayer graphene

Abstract

The ongoing efforts to optimize Li-ion batteries led to the interest in intercalation of nanoscale layered compounds, including bilayer graphene. Its lithium intercalation has been demonstrated recently but the mechanisms underpinning the storage capacity remain poorly understood. Here, using magnetotransport measurements, we report in-operando intercalation dynamics of bilayer graphene. Unexpectedly, we find four distinct intercalation stages that correspond to well-defined Li-ion densities. We refer to these stages as 'in-plane', with no in-plane analogues in bulk graphite. The fully intercalated bilayers represent a stoichiometric compound C14LiC14 with a Li density of 2.7x10^{14} cm^{-2}, notably lower than fully intercalated graphite. Combining the experimental findings and DFT calculations, we show that the critical step in bilayer intercalation is a transition from AB to AA stacking which occurs at a density of 0.9x10^{14} cm^{-2}. Our findings reveal the mechanism and limits for electrochemical intercalation of bilayer graphene and suggest possible avenues for increasing the Li storage capacity.

30 pages, 17 figures

References in corpus (5)

• Electrochemically Top Gated Graphene: Monitoring Dopants by Raman Scattering
• Controlling electron-phonon interactions in graphene at ultra high carrier densities
• Adsorption and ultrafast diffusion of lithium in bilayer graphene ab initio and kinetic Monte Carlo simulation study
• Effects of Lithium Intercalation in Twisted Bilayer Graphene
• Giant atomic swirl in graphene bilayers with biaxial heterostrain