Flexible and mechanically robust Kevlar-bridged MXene film for high-performance supercapacitors

Two-dimensional MXenes exhibit metallic conductivity, pseudo-capacitive mechanism, and robust film-forming capability, recognizing them as promising electrode materials for flexible energy storage devices. However, the use of MXene films in flexible devices is limited by their restricted ionic kinetics, incomplete active site exposure and mechanical strength. Herein, a MXene film electrode with remarkable flexibility, high mechanical strength, and enlarged interlayer spacing is constructed via Kevlar nanofibers intercalation. Systematic coupling allows Kevlar to operate as a bridge and intercalator between MXene flakes, considerably improving mechanical robustness while preventing restacking and increasing interlayer separation. Consequently, being used as electrode for supercapacitors, the MXene/Kevlar film with optimal 30 wt.% Kevlar exhibits high capacitances of 437.8 and 86.5 F g −1 at 1 and 1000 A g −1 in H 2 SO 4 electrolyte, respectively, along with stable cycle performance, retaining a capacity retention of 99.3 % after 10,000 cycles at 10 A g −1 . Moreover, the flexible quasi-solid-state symmetric supercapacitor delivers a maximum energy density of 10.7 Wh kg −1 at a power density of 39.5 W kg −1 , highlighting its potential for application in flexible energy storage devices.