Metal-free on-chip microsupercapacitor with high-aspect-ratio 3D interdigitated pyrolytic carbon microelectrodes derived from additive manufacturing

On-chip microsupercapacitors (μSC) have emerged as promising electrochemical energy storage systems for microelectronic devices. However, the bottleneck to achieve high energy density μSC is the lack of high aspect ratio 3D electrodes enhancing the active material loading on a given footprint area. Here, we introduce a novel strategy combining additive manufacturing and pyrolysis for the on-chip fabrication of 3D pyrolytic carbon microelectrodes with complex hierarchical 3D designs at high structural resolution down to 10 μm. An on-chip μSC based on the interdigitated microelectrode format is demonstrated with the conductive 3D electrodes serving as efficient current collector and electrodeposited polypyrrole as pseudocapacitive material. The influence of polypyrrole deposition, electrode aspect ratio and electrolyte properties on capacitive energy storage is investigated. An UV curable gel polymer electrolyte comprised of Polyethylene glycol diacrylate (PEGDA) and H 2 SO 4 is identified as a viable alternative to Poly (vinyl alcohol) (PVA)-based gel polymer electrolytes demonstrating excellent stability at ambient and low temperatures combined with simple on-chip integration. The resulting encapsulated carbon-based quasi-solid state on-chip μSC exhibits a high specific capacitance of 125 mF cm −2 at 0.5 mA cm −2 and an energy density of 11 μWh cm −2 , which are the highest values reported for pyrolytic carbon-based devices so far. • On-chip additive manufacturing of high aspect ratio 3D polymer microstructures. • Conversion into 3D interdigitated pyrolytic carbon microelectrodes by pyrolysis. • Capacitive energy storage with 3D electrodes after optimized electrodeposition. • Metal-free on-chip microsupercapacitors with PEGDA gel polymer electrolyte. • Specific capacitance 125 mF cm −2 at 0.5 mA cm −2 and energy density 11 μWh cm −2 .