Hybrid graphene electrodes for supercapacitors of high energy density

We describe a process of co-reduction to reduce dispersed graphene oxide (GO) and single-walled carbon nanotubes (SWNTs) simultaneously for preparation of hybrid electrodes for graphene supercapacitors. The SWNTs are in between the inter-layer space of graphene sheets as a spacer to prevent effectively restacking of graphene that often limits seriously the electrochemical performance of graphene supercapacitors. The SWNTs also act as conductive binders to improve the electrical conduction of the electrode. A high specific capacitance of 261 F g−1 for a single electrode and specific energy density of 123 W h kg−1 measured in the two-electrode configuration have been obtained in ionic liquid (EMI-TFSI).