Carbon nanotubes boosts the toughness and conductivity of wet-spun MXene fibers for fiber-shaped super capacitors

Mechanically strong and electrically conducting fibers, particularly those with high specific capacitances, are promising fiber-shaped electrodes for fiber- and textile-based energy storage devices like fiber-shaped supercapacitors (FSCs). However, a high loading of fillers or bridging agents is commonly required to fabricate fiber electrodes with good mechanical strength , which compromises electrical conductivity and energy storage performance. Herein, an easily scalable wet-spinning strategy is reported to fabricate multifunctional Ti 3 C 2 T x MXene/carbon nanotubes (MXene/CNT) hybrid fibers from a harmonious mixture of MXene and CNT in water and using acetic acid as a coagulation bath . The hybrid fiber achieved high strength (61 ± 7 MPa), good conductivity (1142.08 ± 40.04 S cm −1 ) and excellent energy storage performance (∼295 F g −1 at 5 mV s −1 ) at a very low CNT content of ∼1 wt%. When CNT loading increased to ∼9 wt%, the maximum strain at broken reached 161 ± 19 MPa and conductivity further increased to 1715 ± 22 S cm −1 . The excellent mechanical performance allows hybrid fibers to be knitted into textiles for energy storage textiles. The assembled FSCs exhibit energy and power densities of ∼6.08 mW h cm −3 and ∼6440 mW cm −3 , respectively. The excellent performance of MXene/CNT fiber and good feasibility for scalable production will open up new opportunities for the development of wearable and textile-based devices in the near future.