Preparation and Capacitive Properties of Ni-Doped Zinc Cobaltate/Carbon Fiber Composite Porous Mesh Materials

Abstract

Nickel-element-doped zinc cobaltate/carbon fiber composites (Ni-ZnCo2O4/CF) were prepared on carbon cloth (made of a combination of carbon fibers) conductive substrates using a simple ambient stirring method combined with heat treatment. Characterization tests of the materials revealed that the prepared products were porous Ni-ZnCo2O4/CF mesh structures. This porous network structure increases the surface area of the material and helps shorten the diffusion path of ions and electrons. The samples were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) methods to investigate the effect of Ni elemental doping on the stability of the materials. The results show that there are no other impurity peaks and no other impurity elements in the Ni-ZnCo2O4/CF electrode material, which indicates that the sample purity is high. Meanwhile, the electrochemical properties of Ni-ZnCo2O4/CF electrode materials were studied. Under the condition of 15 A·g−1, the specific capacitance of Ni-ZnCo2O4/CF electrode material is 1470 F·g−1, and after 100 cycles, its specific capacity reaches 1456 F·g−1, which is 99.0% of the specific capacity of 1470 F·g−1, indicating that the electrode material has good stability. In addition, we assembled asymmetric supercapacitors (Ni-ZnCo2O4/CF//CNTs) with Ni-ZnCo2O4/CF as the positive material and carbon nanotubes (CNTs) as the negative material. In the cyclic stability experiment of Ni-ZnCo2O4/CF/CNTs devices, when the current density was 1 A·g−1, the specific capacitance was 182 F·g−1. After 10,000 cyclic charge–discharge tests, the specific capacity became 167 F·g−1, which was basically unchanged compared with the initial specific capacity, reaching 91.8%. It shows that it has higher charge–discharge performance and higher cycle stability.