Coaxial Spinning Ti3C2TX MXene Fibers with Spontaneous Radial Densification Achieves Simultaneous Improvements in Both Mechanical Strength and Charge Storage Ability

Abstract

Ti3C2TX MXene with good mechanical strength, metallic conductivity and ultrahigh volumetric capacitance is a promising candidate for developing advanced fibers toward the applications of fibrous supercapacitors (FSCs); however, the weak interlayer interaction, random stacking during coagulation and unsuitable channels for ion transport impose crucial difficulties in continuous spinning strong MXene fibers with desirable charge storage ability. Herein, we propose a coaxial spinning strategy accompanying with spontaneous radial densification for the simultaneous achievements of both improved fiber mechanical strength and charge storage capability. The intercalation of sodium alginate (SA) in core (S/M) expands interlayer spacing and produces suitable paths for ion diffusion, while the presence of SA/graphene oxide (S/G) sheath generates radial compression during dehydration because of capillary force, enhances stress transfer within fiber, and avoid short circuit in FSC. The optimized S/M@S/G fiber exhibits a tensile strength of 238 MPa and a volumetric capacitance of 906 F cm−3 at 1 A cm−3. The assembled FSCs provide a capacitance of 153 F cm−3 together with an energy density of 13.6 mWh cm−3. Notably, owing to the improved mechanical properties, FSCs can be weaved into glove and provide power for an electronic watch.