The electrochemical enhancement due to the aligned structural effect of carbon nanofibers in a supercapacitor electrode

- Supercapacitor using CNFs' aligned structure and deposition of NiCo2O4 is proposed.
- Alignment of carbon nanofibers improves the electrochemical properties.
- Mixed transition metal oxides, NiCo2O4, can offer rich redox faradaic reactions.
- Availability of aligned carbon nanofiber as supercapacitor's electrode is proposed.

Aligned carbon nanofibers (ACNFs) were fabricated by electrospinning using a high speed of rotary collector (2000 rpm). To achieve a synergy effect of the electron double layer and redox faradaic reaction, NiCo2O4 was deposited on the surface of the ACNFs using an electrodeposition method. The improved electrochemical performance of the electrodes was investigated by cyclic voltammetry, galvanostatic charge-discharge testing, and electrochemical impedance analysis. Among the prepared electrodes, which were deposited for different times (5, 10, 20, and 30 s), the sample deposited by NiCo2O4 for 10 s had the highest specific capacitance (90.1 F g−1 at 5 mV s−1), good rate capability (64.7%), and cycle stability (85.2% after 1000 cycles). In addition, to examine the effects of the alignment and redox faradaic reaction of NiCo2O4, the ACNFs covered with NiCo2O4 for 10 s (NC-ACNFs) were compared with the ACNFs deposited by Co3O4 (C-ACNFs) and randomly oriented carbon nanofibers covered with NiCo2O4 (NC-RCNFs). The NC-ACNFs had a 15.8% and 11.3% higher specific capacitance than that of the C-ACNFs and NC-RCNFs, respectively. These results suggested that the electrochemical properties of carbon nanofibers could be improved through the structural effects of aligned nanofibers and a redox faradaic reaction of NiCo2O4.