A Novel Sandwiched Porous MXene/Polyaniline Nanofibers Composite Film for High Capacitance Supercapacitor Electrode

Abstract As a class of promising 2D material, MXenes are widely applied to energy storage systems (ESSs) due to metallic conductivity and high electrochemical activities, but the restacking problem during electrode preparation restricts their electrochemical performances. Herein, polyaniline nanofibers (PANINFs) are used as conductive interlayer spacers to induce the self‐assembly of MXene (Ti 3 C 2 T x )‐based electrode. The favored sandwiched porous structure is formed due to the electrostatic adsorption and hydrogen bond interaction between the positively charged PANINFs and the negatively charged Ti 3 C 2 T x nanosheets, which provide abundant accessible sites and facilitate the diffusion of ions. As a result, the flexible freestanding Ti 3 C 2 T x /PANINFs composite electrode exhibits high conductivity (1373.3 S cm –1 ) and excellent gravimetric capacitance of 645.7 F g –1 . Due to the enhanced structural stability, it achieves impressive cycling stability of 98% capacitance retention after 5000 cycles, which is significantly improved from that of pristine Ti 3 C 2 T x electrode (84.6%). This work provides a feasible strategy for the structure regulation and performance enhancement of MXene‐based supercapacitors, which has great potential in energy storage systems.