3D printing of interdigitated electrode for all-solid-state microsupercapacitors

This paper presents fabrication of interdigitated electrodes for all-solid-state microsupercapacitors by heat-assisted 3D printing. The 3D printing of electrodes features a continuous ejection of a trickle of carbon nanotube (CNT) ink with moderate solid contents. A real-time heating base is employed to regulate the drying of CNT ink so as to ensure the adhesion of two overlapping layers. This allows us to maintain the structural integrity of printed features and to achieve 3D structures of relatively small-sized lateral dimensions by reducing the extent to which extruded ink travels on the base. The microstructure of 3D-printed electrodes is characterized by randomly stacked CNTs and cross-linked pores that are desirable for charge storage. The final all-solid-state microsupercapacitors are made of 3D-printed interdigitated electrodes 124 μm in height, filled with a polyvinyl alcohol-H₃PO₄ gel electrolyte. The electrochemical performance of the microsupercapacitors is characterized by galvanostatic charge-discharge measurements, showing an areal capacitance of 5.9 mF cm^-2 and excellent cycle stability.