Fabrication and Electrochemical Characterization of Single and Multi-Layer Graphene Anodes for Lithium-Ion Batteries

Abstract

Single and multilayer graphene films offer the potential for significant weight reduction in lithium-ion batteries for next-generation power systems, including microbatteries. When scaling down Li-ion battery size and weight, it is important to understand the impact of reducing the number of graphene layers on electrochemical performance. We compared the electrochemical performance of anodes fabricated from pristine single layer graphene (SLG), few layers of multilayer graphene (MLG), and several thousand layers of highly oriented pyrolytic graphite (HOPG). Coin-cell anodes were fabricated without a binder from graphene films grown directly on copper and nickel foils. Cycling at 5 μA/cm2 indicated reversible capacities of ∼0.047 and 0.040 mAh/cm2 for SLG-Cu and MLG-Ni. Subtracting substrate contribution and normalizing to the mass of the graphene layer(s), the specific capacities for SLG and MLG are high (13263 mAh/g and 1185 mAh/g). Distinct peaks were observed in cyclic voltammograms of MLG indicating lithium intercalation into the graphene layers, but not in SLG, suggesting a different mechanism for lithium storage. XPS results of charged SLG-Cu suggest that the reversible charge is present both on top of the SLG and between SLG and Cu. The performance of HOPG was poor (23 mAh/g) and appears to be Li-diffusion limited.