Freestanding supercapacitor electrode applications of carbon nanofibers based on polyacrylonitrile and polyhedral oligomeric silsesquioxane

Abstract

The microstructures and electrochemical performance of polyacrylonitrile/polyhedral oligomeric silsesquioxane (PAN/POSS)-derived carbon nanofibers (CNFs) were investigated in terms of POSS content (0–60wt%) and activation process for their potential utilization as freestanding supercapacitor electrodes. For the purpose, a series of CNFs were manufactured by stabilization and carbonization of electrospun PAN/POSS nanofibers. The CNFs were then activated by potassium hydroxide (KOH) treatment to etch carbon and by hydrofluoric acid (HF) treatment to remove the POSS filler. Scanning electron microscopic images and energy dispersive X-ray spectra of PAN/POSS-based CNFs revealed the efficient removal of the POSS filler by KOH and HF treatments. The effect of POSS content on the porous structures of KOH/HF-treated CNFs was also confirmed by the specific surface area and pore size distribution analyses. The electrochemical performance of the CNFs was evaluated by using cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) test. KOH/HF-treated CNFs, which were fabricated from electrospun nanofibers with 40wt% POSS, were found to have high specific capacitance of 257.7Fg−1 at a scan rate of 5mVs−1 and 116.9Fg−1 at 100mVs−1. The GCD results demonstrated that the CNFs have high specific capacitance of 138.7Fg−1, energy density of 12.2Whkg−1, and power density of 79.6Wkg−1.