Development of high capacity Lithium battery anode materials will have a profound and direct impact on current commercial and emerging markets such as portable electronics, electric vehicles and electric grid storages.

 Graphite’s capacity of intercalating lithium in rechargeable batteries is limited (theoretically, 372 mAh/g) due to low diffusion of lithium atoms within commensurately-stacked infinite graphene layers. Graphene foam with highly enriched incommensurately-stacking layers is grown using Chemical Vapor Deposition (CVD) method and applied as an active electrode in rechargeable batteries. Raman spectroscopy is used to estimate the fraction of incommensurately-stacking layers in a bulk material. ~90% incommensurate graphene foam is demonstrated up to 1540 mAh/g reversible specific capacity at 100 mA/g current density stable throughout hundred cycles with 75-100% Coulombic efficiency. C-rate testing of the electrochemical cells exhibit stability under high current densities which makes these cells feasible.

 XRD, XPS and Raman analysis of graphene anodes show that lithium atoms highly intercalate within weakly interacting incommensurately-stacked graphene structure, followed by a flexible rearrangement of layers for a long-term stable cycling. We have tested several samples with various incommensurateness degree and found that specific capacity is enhanced when commensurately-stacking order of graphene layers is reduced in an anode material¹. The incommensurately-stacked infinite layer graphene cab be considered as a “graphite-like” structure with weakened interplanar interaction which may exhibit exceptionally high lithium capacity of 1116 mAh/g with LiC₂ stoichiometry. New intercalation model of multilayer graphene is considered, where capacity varies with N number of layers, resulting Li_N+1C_2N stoichiometry in which the finite layers of graphene can demonstrate higher capacity, achieving a maximum of 1674 mAh/g in bilayer configuration. An effective capacity increase over six times compared to commonly use commercial graphite battery cells promises the feasibility of the rapid development of lightweight, cost-efficient and high energy density secondary batteries.

1. Paronyan, T. M. et al. Incommensurate Graphene Foam as a High Capacity Lithium Intercalation Anode. Sci. Rep. 6, 39944; doi: 10.1038/srep39944 (2016).