Facile Fabrication of Flexible and Porous Single‐Walled Carbon Nanotubes/Polyaniline Composite Films via a Novel Solution Approach for Supercapacitor Applications

Due to their potential of fast and reversible redox reaction, carbon nanotubes/polyaniline (CNTs/PANI) composites are receiving increasing attention as promising electrode for supercapacitors (SCs). This study explores a facile “direct‐immersion” approach for fabricating single‐walled CNTs (SWCNTs)/PANI flexible composite films for SCs. PANI is dissolved in concentrated sulfuric acid (H₂SO₄) to form a conducting ink, into which the SWCNTs film is soaked. The concentrated H₂SO₄ promotes effective contact between PANI and CNTs, forming stable SWCNT/PANI interface through strong π–π interactions. By controlling reaction conditions, the structural integrity and supercapacitive performance of SWCNT/PANI are improved. Prolonging the immersion time to 24 h results in a flake‐like structure of PANI, with CNTs linking among the flakes. This configuration facilitates ion transport and realizes fast redox reactions. Consequently, a high specific capacitance of 329 F g⁻¹ (at 1 A g⁻¹) is achieved, demonstrating good rate capability and cycling stability. Moreover, the as‐assembled SC devices achieve a high energy density of 14 Wh kg⁻¹ at a power density of 400 W kg⁻¹. These devices exhibit remarkable electrochemical durability, without occurring obvious capacitance deterioration after 5000 charge/discharge. This work paves the way for the design and fabrication of high‐performance PANI‐based SCs.