Electrochemical improvement due to alignment of carbon nanofibers fabricated by electrospinning as an electrode for supercapacitor

Abstract

Aligned carbon nanofibers (CNFs) were fabricated by electrospinning to evaluate the potential of aligned one-dimensional structure as a supercapacitor electrode. First, randomly oriented polyacrylonitrile (PAN) nanofibers were fabricated, and aligned PAN nanofibers were prepared by increasing the speed of the rotary collector from 250 to 2000 rpm. The prepared PAN nanofibers were carbonized for use as a supercapacitor electrode. According to increase of speed of collector, the specific surface area and electrical conductivity were improved from 533 to 635 m2 g−1 and from 342 to 626 S cm−1, respectively. This result might be caused by increased pulling strength between the fibers and the surface of the collector generated by electrospinning as well as the unique aligned nanostructure of CNFs. The specific capacitance and rate capability of the aligned carbon nanofibers (CNFs) were increased by 35.5 and 28.4%, respectively, compared to the randomly oriented CNFs. The enhanced surface area, micropore volume (from 0.19 to 0.24 cm3 g−1), mesopore volume (from 0.08 to 0.26 cm3 g−1), and aligned structure make an impact upon the unique electrochemical properties both low scan rate (10 mV s−1) and high scan rate (50 mV s−1).