Nacre-inspired surface-engineered MXene/nanocellulose composite film for high-performance supercapacitors and zinc-ion capacitors

Ti3C2Tx is a promising electrode material for supercapacitors, whereas it suffers from the re-stacking problem and fluorine-rich functional groups, thereby restricting its electrochemical performance. Herein, delaminated Ti3C2Tx flakes are modified by alkalization and post-annealing treatments to considerably decrease –F and –OH functional groups. In addition, inspired by the architecture of nacres, the modified Ti3C2Tx is combined with soybean stalk-derived nanofibrillated cellulose, which can improve mechanical properties, prevent dense packing of Ti3C2Tx, and facilitate the transport of electrolyte ions. Therefore, the optimized composite film exhibits large tensile strength (53.9 MPa), high electrical conductivity (24930 S m−1), and superior electrochemical performance for supercapacitors and zinc-ion capacitors. In particular, the composite film under quasi-solid-state supercapacitor configuration delivers high capacitances of 303.1 and 211.4 F g−1 at 1 and 10 mA cm−2, respectively, excellent cyclability (92.84% capacitance retention over 10,000 cycles), and great affordability to bending deformations. This work offers an efficient way to construct high-performance flexible electrodes for high-power applications.