Foamed graphene flakes from the one-step pyrolysis of PEG/MgO composites for supercapacitors and lithium-ion batteries†
Three-dimensional graphene-like materials can effectively prevent the restacking of graphene layers and show tremendous potential applications in practice. In the present work, foamed graphene flakes (FGs) were easily prepared by a one-step pyrolysis of polyethylene glycol-200 (PEG)/MgO composites, and they were successfully applied in supercapacitors and lithium-ion batteries (LIBs). The FGs consisted of a large number of foamed flakes, and each flake was made up of 3 to 10 graphene layers. By changing the weight ratio of PEG/MgO, the specific surface area, porosity, and graphitization of the FGs could be adjusted. As electrode materials of supercapacitors, FGs from the PEG/MgO at a weight ratio of 1 : 1.5 showed the highest areal capacitance of 29.5 μF cm−2 and a retention rate of 92%. As the anode materials of LIBs, FGs from PEG/MgO at a weight ratio of 4 : 1.5 had a reversible discharge capacity of 787 mA h g−1 at a current density of 0.2C, and showed excellent rate performance and cycling stability. These FGs have significant potential for practical application in electrochemical energy storage.