Additive-Free MXene Inks and Direct Printing of Micro-Supercapacitors

Direct printing of functional inks is critical for applications in diverse areas including electrochemical energy storage, smart electronics and healthcare. This chapter demonstrates two types of two-dimensional titanium carbide MXene inks, aqueous and organic in the absence of any additive or binary-solvent systems, for extrusion printing and inkjet printing, respectively. It presents examples of all-MXene-printed structures, such as microsupercapacitors, conductive tracks and ohmic resistors on untreated plastic and paper substrates, with high printing resolution and spatial uniformity. The main challenges of realizing precise MXene printing lies either in the MXene ink formulation or the solvent evaporation kinetics, or both. The additive- and binary- solvent-free, low-temperature printing technique suggests new possibilities for applications in smart electronics, sensors, electromagnetic shielding, antennas and other applications. The versatile direct-ink-printing technique highlights the promise of additive-free MXene inks for scalable fabrication of easy-to-integrate components of printable electronics.