Graphene Aerosol Gel Ink for Printing Micro-Supercapacitors

Synthesizing crumpled and porous graphene with sub-100-nm particle size and dispersing them uniformly in a solvent to form a stable colloidal suspension are key factors for obtaining a promising route toward graphene-based printed electronics. Here, we report the formulation of a stable graphene aerosol gel ink that could be used in number of technologies, such as supercapacitors for printed electronics. We use a gel-type graphene nanostructure, called graphene aerosol gel, synthesized via an energy efficient, catalyst-free, and nonhazardous chemical precursor detonation method, such as hydrocarbons (e.g., acetylene) in the presence of controlled oxygen. As a proof of concept, in this work, we have used the formulated graphene aerosol gel ink to print microsupercapacitors in interdigitated electrodes (IDEs) geometry on 25-μm thick polyimide substrates using a microplotter. The graphene aerosol gel printed IDE microsupercapacitors with 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF₄) ionic liquid (IL) electrolyte demonstrate promising supercapacitor stability when electrochemically cycled between 0 and 1 V potential window. These printed microsupercapacitors show an aerial capacitance of 55 μF/cm² and volumetric capacitance of 3.25 F/cm³ at a current density of 6.0 microamp/cm² and 20 milliamp/cm³, respectively. The printed devices do not show a significant distortion in the cyclic voltammetry scan even at a high scan rate of 2000 mV s^–1 and demonstrate ∼80% of capacitance retention after 10 000 cycles of operation, making our graphene aerosol gel ink a promising ink technology for printed energy storage devices and systems.