Preparation and electrochemical properties of carbon nanofibers derived from polybenzimidazole/polyimide precursor blends

Carbon nanofibers (CNFs) were fabricated by thermal treatment of electrospun nanofibers obtained from precursor blends of polybenzimidazole (PBI) and Matrimid®. The microcarbon structures of CNFs obtained from PBI, and the 50:50 and 75:25 blends were studied using XRD and Raman spectra. Nitrogen adsorption/desorption measurements revealed that surface area and porosity of CNFs increased with an increase in Matrimid® content. Electrochemical performance of these CNF electrodes was studied for their application in energy storage devices. The CNFs from the PBI/Matrimid® (75:25)-precursor blend showed the lowest electrochemical impedance, and highest specific capacitance (111 F/g) and energy and power densities of 24 and 6 kW/kg, respectively. Steam activation and annealing further enhanced the performance resulting in a specific capacitance of 126 F/g, and energy and power densities of 49 and 7 kW/kg, respectively.