Excellent oxidation resistive MXene aqueous ink for micro-supercapacitor application

Uniform and stable interdigitated electrodes are essential for planar micro-supercapacitor applications. Two-dimensional (2D) materials, such as transition-metal MXenes have become attractive nanomaterials for micro-supercapacitor applications due to their layered structure and high electrical conductivity. However, the low stability of MXenes in aqueous media limits their long-term storage and application. Here, we demonstrate in-situ synthesis and capping of Ti₃C₂T_x MXenes with sodium ascorbate (SA) to obtain SA-MXene dispersion with high resistance against oxidation even after 80 days of storage at ambient temperature and exposed to air. The in-situ synthesis process increases the interlayer spacing of SA-MXene sheets, and increases their energy storage efficiency, without compromising their electrical conductivity. A printable SA-MXene ink was prepared with Triton X-100 and propylene glycol as modifiers to print interdigitated micro-supercapacitor electrodes with an inkjet printer. Our solid-state micro-supercapacitor made without current collector exhibits areal and volumetric capacitance of 108.1 mF cm⁻² and 720.7 F cm⁻³, respectively. This work highlights the potential application of ligand-capped stable MXenes as a water-based ink in printing devices for the fabrication of micro-electronics and supercapacitors.