Preparation Of Honeycomb Porous Nanofibrous Carbon Membranes By Electrospinning And Their Applications For Supercapacitors

Carbon materials have the advantages of good conductivity, high specific surface area, resistance to high temperature and acid/base, pollutant free to the environment and low cost when used as electrodes of supercapacitors. Carbon nanomaterials have long attracted great interest due to their unique properties oringinating from their nanoscale dimension. In this study, honeycomb porous nanofibrous membranes (HPNMs) of polyacrylonitrile (PAN) were prepared by self-assembly during electrospinning, and the carbon HPNMs were subsequently obtained by carbonization. SEM, TGA, FT-IR and Raman Spectroscopy were used to study the formation of the HPNMs and their carbonization process; the electrochemical behavior of the carbon HPNMs was investigated by electrochemical workstation.The factors influencing the formation of PAN HPNMs include molecular weight, concentration, temperature, humidity and the electrospinning parameters. SEM images indicated through optimizing the above factors, the HPNMs with well-defined polygonal pore structures can be achieved.The effect of temperature and heating rate of preoxidation, collectors and carbonization temperature on the formation of carbon HPNMs was also studied. Too high heating rates in preoxidation caused severe cracking of the membrane. As revealed in FT-IR, the membrane could be fully preoxidized at 250℃. When carbonizing, while collectors tended to hinder stress relief and cause cracking, the honeycomb porous nanofibrous structure can only be reserved with free standing HPNMs. Raman spectrogram showed that the degree of graphitization increased with increasing carbonization temperature.Lastly cyclic voltammetry (CV), chonopotentiometry and ac impedance test were utilized to study the electrochemical behaviors of the carbon HPNMs. All CV curves approached the ideal rectangular shape. High specific capacitance (SC) at different current densities was obtained, which was much larger than that of disordered carbon nanofiber membranes also prepared by electrospinning. The highest SC of 129.23F/g obtained at the current density of 420mA/g was comparable with that of activated carbon nanofiber membranes. The carbon HPNMs showed great potential in supercapacitor application.