In-situ selective surface engineering of graphene micro-supercapacitor chips

Surface modification of graphene oxide (GO) is a powerful strategy to develop its energy density for electrochemical energy storage. However, pre-modified GO always exhibits unsatisfactory hydrophilia and its ink-relevant utilization is extremely limited. Although GO ink is widely utilized in fabricating micro energy storage devices via extrusion-based 3D-printing, simultaneously obtaining satisfactory hydrophilia and high energy density still remains a challenge. In this work, an in-situ surface engineering strategy was employed to enhance the performance of GO micro-supercapacitor chips. Three dimensionally printed GO micro-supercapacitor chips were treated with pyrrole monomer to achieve selective and spontaneous anchoring of polypyrrole on the microelectrodes without affecting interspaces between the finger electrodes. The interface-reinforced graphene scaffolds were edge-welded and exhibited a considerably improved specific capacitance, from 13.6 to 128.4 mF·cm−2. These results are expected to provide a new method for improving the performance of micro-supercapacitors derived from GO inks and further strengthen the practicability of 3D printing techniques in fabricating energy storage devices.