Hierarchically porous CNF-CNT@PANI nanocomposite aerogels for flexible supercapacitors with high specific capacitance and electrochemical stability

Flexible supercapacitors have emerged as promising energy storage devices, owing to their high power density and long cycle life. However, the development of electrode materials with high specific capacitance, superior electrochemical and mechanical stability remains a critical challenge. In this work, we report a facile strategy for fabricating cellulose nanofiber (CNF)-carbon nanotube (CNT)@polyaniline (PANI) nanocomposite aerogels via TEMPO oxidation, freeze-drying, and in-situ polymerization. The CNFs serve as a dispersive scaffold to uniformly distribute CNTs, forming a three-dimensional (3D) interconnected network, while PANI coats the CNF-CNT hybrid to construct a core-shell structure, enhancing pseudocapacitive performance. The resulting CNF-CNT@PANI aerogel exhibits a hierarchical porous structure with a high specific surface area of 121.4 m 2 g -1 and low density of 12.8 mg cm -3 . The assembled flexible supercapacitors deliver a high areal specific capacitance of 722.4 mF cm -2 at 2 mA cm -2 , long-term capacitive cyclic stability (86% capacitance retention after 3000 cycles), and remarkable mechanical stability (95.2% capacitance retention after 200 bending cycles). Additionally, the device achieves a maximum areal energy density of 99.5 μWh cm -2 at a power density of 1005.4 μW cm -2 , outperforming many reported PANI-based supercapacitors. This work provides a feasible approach for designing high-performance flexible electrode materials for next-generation energy storage systems.