The interconnected carbon nanofibers were prepared by an electrospinning technique using a polymer solution composed of polyacrylonitrile (PAN), poly(acrylonitrile-co-butadiene (PAN-co-PB) copolymer, and N,N-dimethylformamide. Post-treatment including stabilization at 250 degrees C and carbonization at 800 degrees C converted electrospun fibers to bonded carbon nanofibers. The formation of interconnected carbon nanofibers was attributed to the decomposition of PB, which reduced the viscosity of nanofibers and caused the fusion of connecting points. As a result, the conductive pathways developed, leading to an increase in both the electrical conductivity and microcrystallite size. Electrochemical measurements revealed that the specific capacitance of the 90:10 PAN/PAN-co-PB derived carbon nanofibers was 170.2 F/g, which was about 24% higher than that of the neat PAN-derived carbon nanofibers. Furthermore, the fibers showed good cycling stability of energy storage with the retention ratio of 100% after 2000 cycles. Our results corroborated the advantage of these interconnected nanofibers. (c) 2014 Elsevier Ltd. All rights reserved.