Effect of gel electrolytes on the performance of a minimized flexible micro-supercapacitor based on graphene/PEDOT composite using pen lithography

The objective of this study was to fabricate a minimized all solid-state micro-supercapacitor (MSC) with a patterned graphene flake (GF)/polyethylenedioxythiophene (PEDOT) composite electrode using pen lithography. This MSC demonstrated properties of a suitable gel electrolyte. It involved direct writing of GF/PEDOT composite inks with a layer-by-layer assembly and polymerization method by pen lithography on a very small area (0.38 cm²) without needing complex processing or a cleanroom environment. Furthermore, performances of three different gel electrolytes (PVA/H₂SO₄, LiClO₄, and H₃PO₄) in the MSC were investigated to obtain an MSC with high power density. Results revealed that GF/PEDOT-MSC with PVA/H₂SO₄ gel electrolyte demonstrated excellent electrochemical features such as maximum operating potential window (1.2 V), specific capacitance of 37.08 mF cm⁻², and energy density of 6.4 mWh cm⁻² with extended cycling stability up to capacitance retention rate of 89% after 2500 cycles. This study suggests potential applications of these electrode materials for an easy and scalable fabrication of a wide variety of devices.