MXene/Carbon Nanotube Composite Yarn for Energy Storage and Electromagnetic Interference Shielding

MXene or MXene‐based composite fibers hold potential for powering flexible, wearable smart garments as flexible capacitors. However, pure MXene suffers from extremely poor mechanical properties, while MXene composite fibers exhibit low specific capacitance, both of which limit their practicality for wearable smart clothing applications. To overcome the challenge of low specific capacitance in MXene composite fibers, carbon nanotube (CNT) yarn was acted as an important substrate to be coated with MXene to obtain MXene/CNT yarn supercapacitor (YSC) with excellent electromagnetic interference shielding (EMI). By fully leveraging the synergistic effect between MXene and CNT yarn, the MXene/CNT yarn achieved a conductivity of 1263.82 S/cm with a MXene loading of 0.41 mg/cm. The thermodynamics and kinetics of the coating process were examined. The MXene/CNT YSC achieved a specific capacitance of 70.25 F cm −1 at 20 mV s −1 and 183 F cm −3 at 0.1 A cm −3 and a capacitance retention of ≈86% after 12,000 galvanostatic charge–discharge (GCD) cycles at 0.1 A cm −3 . A fully woven MXene/CNT fabric provided EMI shielding of 35 dB with a thickness of 0.45 mm. Our work provided a new strategy for fabricating energy storage yarns with outstanding EMI shielding performance.