Screen-printing fabrication of high volumetric energy density micro-supercapacitors based on high-resolution thixotropic-ternary hybrid interdigital micro-electrodes

Abstract

Printed micro-supercapacitors (MSCs) have been acknowledged as promising on-chip energy storage systems for miniaturized printed electronics. However, scalable fabrication of the printed MSCs with both high energy density and power density as well as micrometer-level electrode resolution remains unsolved. Herein, we demonstrate a general and scalable screen-printing technique for the one-step construction of high-performance MSCs, utilizing thixotropic hybrid ink of hydrous ruthenium oxide (RuO₂·xH₂O) nanoparticles–silver nanowire (AgNW)–graphene oxide (GO) as interdigital in-plane microelectrodes. Benefited from the synergistic effects from the ternary nanocomponents, high-resolution microelectrode fingers of up to 50 μm, and outstanding electrical conductivity >5000 S cm⁻¹ of microelectrode, the resulting fully-printed MSCs deliver record volumetric capacitance of 338 F cm⁻³, landmark volumetric energy density of 18.8 mW h cm⁻³ and power density of 40.9 W cm⁻³, all of which are higher than those of previously reported printed MSCs. Furthermore, our printed MSCs exhibit long-term cycling stability with a high capacitance retention of 91.6% after 8000 cycles, and remarkably mechanical flexibility, showing 88.6% of initial capacitance after 2000 bending cycles. Finally, this simple printing approach in junction with high functionality of the electrode ink enables the fast and scalable fabrication of flexible MSCs with various geometries and efficient production of MSC arrays connected in series and/or in parallel connection without requirement of additional metal-based contacts and interconnectors, showing great potential for applications in wearable system-on-a-chip.