An easily manipulated protocol for patterning of MXenes on paper for planar micro-supercapacitors

Recently, a unique class of bidimensional layered transition-metal carbides/nitrides, namely MXenes, has shown great potential for use in high-performance on-chip microsupercapacitors (MSCs). Patterning of MXenes on film substrates to form coplanar interdigital electrodes is the key to realize the fabrication of high-performance MXene-based planar MSCs. Herein, through a combination of ordinary laser printing, vacuum-assisted deposition and physical sputtering, a simple protocol for fast and on-demand patterning of few-layered MXene flakes on paper into a coplanar arrangement to fabricate planar symmetric MSCs is reported. Benefiting from the as-obtained binder/conductive-additive free MXene-based interdigital electrodes with a unique layered porous structure and high electrical conductivity attributed to the good alignment along the c-axis of the closely restacked few-layered MXene flakes, the as-fabricated all-solid-state planar MXene-based symmetric MSCs can acquire a maximal areal capacitance of 27.29 mF cm-2as the thickness of the MXene electroactive layer increases, achieving at least 460% enhancement compared to the value of advanced carbon-based planar symmetric MSCs (0.1-6 mF cm-2), without obvious deterioration of the volumetric capacitance. Our work provides a simple and convenient platform to fabricate MXene-based on-chip symmetric MSCs with thick coplanar interdigital electrodes to increase the capacity per device within a limited footprint.