Polyaniline/Small‐Sized MXene/Carbon Cloth Electrodes with 3D Hierarchical Porous Structure for All‐Solid‐State Flexible Supercapacitors

The porous structure of electrodes can exert a significant impact on electrochemical performances of supercapacitors. Herein, the polyaniline/small‐sized MXene/carbon cloth (PANI/S‐MXene/CC) electrodes with 3D hierarchical porous structure are fabricated by a facile single‐step pulsed electrodeposition. First, the PANI/S‐MXene nanowires closely overlap each other and form a nanosized pore structure, which provides large specific surface area and abundant ion diffusion channels. Second, the CC with a large pore structure can facilitate permeation of gel electrolyte. S‐MXene with small lateral size not only decreases charge transfer resistance of electrodes, but also ensures an interconnected porous framework. Consequently, the assembled all‐solid‐state flexible device delivers a high areal capacitance (478.4 mF cm −2 at 0.5 mA cm −2 ), a superior rate capability (307.5 mF cm −2 at 10 mA cm −2 ), a remarkable energy density (42.5 μWh cm −2 ), favorable cycle stability (75.4% capacitance retention after 4000 cycles), as well as 93.2% capacitance retention after 180° mechanical bending with 1000 cycles. Herein, it is revealed that size selection of nanomaterials is a priority when the porous structure is designed.