3D Interdigitated Microsupercapacitors with Record Areal Cell Capacitance

Due to their high-power density and long lifetime, microsupercapacitors have been considered as an efficient energy supply/storage solution for the operation of small electronic devices. However, their fabrication remains confined to 2D thin-film microdevices with limited areal energy. In this study, the integration of all-solid-state 3D interdigitated microsupercapacitors on 4 in. silicon wafers with record energy density is demonstrated. The device electrodes are composed of a pseudocapacitive hydrated ruthenium dioxide RuO₂ deposited onto highly porous current collectors. The encapsulated devices exhibit cell capacitance of 812 mF cm^-2 per footprint area at an energy density of 329 mJ cm^-2 , which is the highest value ever reported for planar configuration. These components achieve one of the highest surface energy/power density trade-offs and address the issue of electrical energy storage of modern electronics.