Activated Carbon Nanofibers Derived from Thermally Rearranged Polyimides for Binder‐Free Supercapacitors

Supercapacitors (SCs) based on carbon nanofibers (CNF S ) are being paid much attention due to their fast charge–discharge rate, high power density, and excellent cyclic stability. Herein, a kind of preferred hydroxyl‐containing poly(amic acid) solution is first synthesized by using 2,2‐bis(3‐amino‐4‐hydroxyphenyl)hexafluoropropane and pyromellitic dianhydride as monomers, and electrospun to prepare nanofiber membranes. Then, thermal imidization, thermally rearranged treatment, and carbonization are employed to successfully fabricate the corresponding hydroxyl‐containing polyimide (HPI)‐CNFs. Next, the activated CNF S are obtained through a simple activation treatment with KOH. After optimizing the concentration of KOH solution, the self‐standing and binder‐free CNF electrode A–HPI–CNFs–1/3 exhibits a maximum specific surface area of 2058 m 2 g −1 and pore volume of 1.04 cm 3 g −1 , leading to a high specific capacitance of 387.7 F g −1 at 0.5 A g −1 and rate capability of 70% at 10 A g −1 . In addition, the assembled symmetrical SC device shows outstanding cycle stability performance after 50000 runs of charge–discharge with a specific capacitance retention of 99.93% at 1 A g −1 . Finally, the SC demonstrates a specific power of 12.7 Wh kg −1 at a specific energy of 250.0 W kg −1 , suggesting potential application prospects in the field of SCs.