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.