Surface Tension-Driven Self-Planarization of MXene Liquid Crystalline Fiber for High-Performance Energy Storage.

2D MXene-based liquid crystalline (LC) systems have emerged as promising precursors for constructing highly ordered functional materials, such as fibers, films, and aerogels via solution-based processing. In this study, we demonstrate surface tension-mediated self-planarization of MXene LC fibers by adjusting the solvent composition during wet-spinning, targeting improved electrochemical performance. Ethanol, a poor solvent for MXene, induced spontaneous parallel alignment of MXene platelets and facilitated densification into a ribbon-like geometry during coagulation. The resulting fibers featured a pore volume of 0.11 cm3 g-1 and an average pore diameter of 34 nm, enabling a volumetric capacitance of 1721.7 F cm-3 and an electrical conductivity of 9211.66 S cm-1. The mechanism underlying the self-planarization was investigated by using a range of solvents with varying physicochemical properties to identify key processing parameters. The MXene fibers were successfully implemented into LED-powered supercapacitor prototypes, demonstrating potential applicability for wearable energy applications.