Engineering coaxial MXene@CNT fibers via wet-spinning for balanced mechanical, electrical, and electrochemical performance

Ti 3 C 2 T x MXene fiber has excellent electrical conductivity and energy storage properties, making it ideal for manufacturing fiber-shaped supercapacitors (FSCs). However, optimizing the MXene fiber electrode structure to improve mechanical properties and maintain maximum energy storage performance remains a critical challenge. This report presents a coaxial structure of MXene@carbon nanotube (CNT) fiber and realizes the regulation of fiber properties. Compared with MXene/CNT hybrid fibers with the same ratio, MXene@CNT coaxial fibers offer a higher electrical conductivity (4553.93 ± 108.15 S cm −1 ) and mechanical strength (tensile strength of 147.51 ± 13.02 MPa). This can be attributed to the good force transfer and intact of conductive channels in the continuous phase in MXene and CNT layers. Notably, the CNT sheath has negligible effect on the diffusion of electrolyte and the coaxial fiber demonstrates a higher specific capacitance of up to 1268 F cm −3 at high current density of 1 A cm −3 , along with excellent rate performance and long-cycle stability. When assembled into supercapacitors, the MXene@CNT coaxial fiber achieves a high energy density of ∼11.61 Wh kg −1 and a power density of ∼6007.14 W kg −1 . This study provides insight into structural engineering for the large-scale preparation of high-performance MXene-based composite fibers.