Scalable fabrication of MXene-based flexible micro-supercapacitor with outstanding volumetric capacitance

This work demonstrates a facile and reliable process for scalable and sustainable manufacturing of on-chip and flexible microsupercapacitor (MSC) devices for future applications in wearable/portable and miniaturized microelectronics. MSCs, which can provide high power density and a virtually unlimited lifetime, can be used as power supplies integrated into electronic systems. However, lower volumetric capacitance and energy density of conventional double-layer carbon supercapacitors limits their practical applications. In this study, a microfabrication process based on photolithography and a solution process were used to fabricate interdigitated micro-patterns of pristine MXene and 3D interconnected nanoporous MXene electrodes, which were then transferred onto flexible substrates. These flexible MSCs have properties that meet expectations for scalable manufacturing (107 chips in an 8 in.-wafer). They have an outstanding volumetric capacitance of 1,727F cm⁻³ (the highest ever reported for MXenes), desirable customization (essential at the 8-inch level of integrated microelectronics), and a remarkable energy density of 41.9 mWh cm⁻³, which is maintained at a high-power density of 26.8 W cm⁻³. Furthermore, the volumetric capacitance increased by approximately 140 % after 10,000 bending cycles, which was only observed in the planar interdigitated electrode micropatterns made of 2D MXene sheets and subjected to tensile stress on flexible polymer substrates.