Inkjet-Printed Flexible Graphene-Based Supercapacitor

• A flexible, inkjet-printed, graphene-based supercapacitor has been demonstrated with a graphene specific capacitance of up to 192 F/g.
• Repeated bending of the device for hundreds of cycles resulted in a loss of capacitance of less than 5%.
• The permeability of the Kapton packaging materials is a problem for the common aqueous and organic electrolytes, but ionic liquids appear to be well contained.

A flexible supercapacitor is being developed for integrating with and powering flexible electronics for military and commercial applications. Graphene oxide dispersed in water was used as an ink for inkjet printing the electrode active material onto metal film on Kapton current collectors. After printing, the graphene oxide was thermally reduced at 200 °C to produce conductive graphene electrodes. These electrodes were heat sealed together with added electrolyte and separator, and the assembled supercapacitor performance was evaluated. The specific capacitance of the graphene is good, and the overall performance of the packaged device serves as a proof of concept. But in the future, thicker graphene electrodes and further package optimization will be required to obtain good device-level performance. A number of issues associated with using Kapton for packaging these devices are identified and discussed.