Home – Home – Jornals – Chemistry for Sustainable Development 2019 number 6

Preparation and properties of nanostructured composites promising for the development of electrode materials for supercapacitors are considered. The composites are based on carbon fibres made of multiwalled carbon nanotubes (MCNT), filled with the nanoparticles of mixed cobalt and nickel hydroxides which are deposited on the surface and in the channels of these nanotubes. The composition and morphology of nanostructured composites were studied using transmission electron microscopy and X-ray diffractometry, including the method of small-angle X-ray scattering and X-ray fluorescence analysis. The electrochemical properties of the obtained electrode nanocomposite material were considered. It is shown that variations of the cobalt to nickel ratio in the composition of the mixed hydroxide lead to significant changes in the electrochemical properties of composite electrodes. In general, an increase in their capacitance is due to the contribution of the pseudocapacity of nickel-cobalt hydroxides, and the highest capacitance values are achieved with the Co/Ni ratio close to 1 : 1. Analysis of voltammetric curves also revealed a decrease in the specific electric capacity of the electrode material with an increase in scanning rate for samples having a pseudocapacity component, which was obtained by matrix functionalization and the introduction of cobalt and nickel hydroxides, because redox reactions on the electrodes proceed with lower rates than charge accumulation due to the double electrical layer. The functionalization of carbon nanofibres consisting of multilayer carbon nanotubes was carried out by ozonation, followed by the introduction of a hydroxide filler containing transition metal hydroxides. This treatment caused an increase in their specific electric capacity, thus it is promising for the development of highly efficient electrode materials based on carbon matrices.