Fabrication of NiCo2O4 and carbon nanotube nanocomposite films as a high-performance flexible electrode of supercapacitors

Abstract

Herein, we demonstrated facile fabrication of NiCo₂O₄ nanoparticles on a CNT film by a chemical deposition method, followed by thermal annealing treatment processing. The synthesized NiCo₂O₄/CNT nanocomposite films were still highly flexible, porous, and conductive. Scanning electrical microscopy (SEM) and transmission electronic microscopy (TEM) observation showed that the web-like structure of the films is still preserved and each carbon nanotube in the film was uniformly wrapped by ball-like nanoparticles (ca. 5 nm). X-Ray Diffraction (XRD) measurement confirmed that spinel NiCo₂O₄ was successfully synthesized during the experiment. The contents of NiCo₂O₄ in the composite films could be controlled by tuning the deposition times. The flexible, porous and conductive nanocomposite films could be employed as high-performance flexible energy saving installments. The three-pole measurements illustrated that the composite films possessed a capacitance of 828 F g⁻¹ at 1 A g⁻¹, and retained over 99% of their capacitance after 3000 cycles of charge/discharge at 5 A g⁻¹, showing high-performance electrochemical properties. Finally, an asymmetric supercapacitor installment was assembled by using the composite film as the positive electrode and commercially available activated carbon (AC) as the negative electrode. The measurement gave an energy density of 28.58 W h kg⁻¹ at a power density of 0.7 kW kg⁻¹.