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Preasphaltene (PA) in coal liquefaction residues is a major precursor for synthesizing carbon nanofibers film by electrospinning, stabilization and carbonization. In this study, terephthalic acid (TPA) was used as an additive in a spinning solution to improve the nanostructural and electrochemical performance of PA based carbon nanofibers (PACF). The effect of TPA on the stabilization, carbon nanostructural characteristics and electrochemical performance of the supercapacitors for PACF were characterized and evaluated. The results showed that TPA could promote the oxidation of PA and decelerate the weight loss rate of the stabilized fibers, affording a good fiber morphology and satisfactory flexibility. Furthermore, the introduction of TPA facilitated the generation of pore structures in carbon nanofibers, which heightened the specific surface area, resulting in an elevated specific capacity (204 F g−1 at 1 A g−1) alongside excellent cycling stability (97.5 % capacitance retention after 10,000 cycles at 2 A g−1). [Display omitted] • The effect of TPA on the stabilization of PA/PAN film was investigated. • The influence of TPA in nanostructural characteristics of PACF was evaluated. • TPA improved the pore structures and enhanced specific surface area of PACF. • TPACF-3 exhibits good electrochemical performance for SCs. [ABSTRACT FROM AUTHOR]

In this study, amorphous zinc oxide incorporated with sulfur-doped carbon composite nanofiber (ZnO@S-CNF) was obtained through a facile electrospinning technique and calcination. The ZnO@S-CNF composite was characterized in detail in order to understand the structural features of the electrodes and applied for supercapacitors. As a self-supporting electrode, it achieved a high capacitance of 209 F/g at 1 A/g and sustained 158 F/g at 10 A/g. Also, an asymmetric supercapacitor (ASC) assembled by ZnO@S-CNF as the positive and carbon nanofiber as the negative electrode (−CNF//ZnO@S-CNF+) achieved a specific energy of 11.2 Wh/kg at a specific power of 900 W/kg in 0–1.8 V. The excellent electrochemical performance can be ascribed to the enhanced surface area, increased micropore volume, and heteroatom content. This study can provide a feasible way for the development of other carbon composite electrodes with remarkable performance. [Display omitted] • Modification of the electronic structure by heteroatom doping, thereby promoting the supercapacitive performance. • Increased surface area with the synergistic effect of amorphous zinc oxide and introduction of sulfur in the carbon skeleton. • ASC device with a specific energy of 11.2 Wh/kg at a specific power of 900 W/kg. [ABSTRACT FROM AUTHOR]