Effects of stabilization on structures and properties of Electrospun Polyacrylonitrile based carbon nanofibers as a binder free electrode for supercapacitor application

Abstract

Electrospun nanofibers were produced with Polyacrylonitrile (PAN) precursor using the Electrospinning technique. Stabilization is an important heat treatment process before carbonization. A total of 2 samples were considered for the carbonization process. Electrospun Pure PAN nanofiber mat was used with aluminium foil substrate for the heat treatment process in a tube furnace. The first sample was stabilized at 290 °C temperature at a 2 °C/min heating rate and constant heating for 3 h. The second sample was directly used for carbonization without stabilization. Fibers were carbonized at 500 °C under a nitrogen atmosphere with a dwell time of 1 h. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to study the influence on structures and properties of carbon fibers of both samples. To investigate elemental concentration in samples Energy-dispersive X-ray spectroscopy (EDX) was used. EDX results showed 45 % and 60 % carbon atom non stabilized and stabilized carbon nanofibers respectively. An SEM result reveals a drastic fiber diameter reduction in a sample that was not stabilized before carbonization as compared with the sample which was stabilized before the carbonization process. FTIR results showed the complete conversion of CN to CN at a stabilization temperature of 290 °C. Also, FTIR results reveal that 500 °C temperature is too low for complete carbonization as some peaks are still there after the carbonization. Low temperature carbonization is necessary to avoid the melting of aluminium foil substrate during the carbonization process. Further CNF mat will be peeled off from the substrate and will be used directly as electrode material for electrochemical characterization.