Development of carbon nanofibers based on rearrangeable polyimides containing O/N/S heteroatoms for supercapacitor applications

Heteroatom-doped carbon electrodes have garnered significant interest. Herein, a novel hydroxyl-functionalized diamine monomer, 4,4′-bis(4-amino-3-hydroxyphenoxy)diphenyl sulfide (BAHPDS), is synthesized and polymerized with 4,4′-(hexafluoroisopropylidene)diphthalic anhydride to produce a poly(amic acid) solution (PAA). Then, the electrospun PAA membrane is subjected to stepwise thermal treatment for imidization, rearrangement, and pyrolysis. When the carbonization temperature and PAA concentration are individually adjusted to 800°C and 20 wt%, the obtained carbon nanofiber (CNF) sample presents a capacitance of approximately 224 F g −1 . Next, KOH activation treatment is carried out. Upon achieving an optimal weight ratio of activator to CNF of 3:1, the obtained specimen demonstrates an enhanced specific capacitance of approximately 330.7 F g −1 , along with a rate performance of approximately 73% from 0.5 to 10 A g −1 . Moreover, the coin-type supercapacitor constructed using the self-supported membrane electrodes attains a maximum energy density of 11.26 Wh kg −1 at 249.9 W kg −1 and showcases exceptional operational stability over 10,000 charging-discharging cycles without significant degradation. This work develops a novel rearrangeable polyimide containing O/N/S heteroatoms as a precursor to fabricate CNFs for supercapacitor applications, which provides certain insights into self-supporting carbon electrode materials.