Study of functional characteristics of mesoporous electrodes of supercapacitors based on silicon-carbon films

Abstract

The study of the supercapacitor electrodes based on silicon-carbon films obtained by electrochemical deposition from solutions with different ratios of methanol/hexamethyldisilane and addition of manganese and nickel salts was carried out using cyclic voltammetry, electrochemical impedance spectroscopy and impedance Nyquist plots simulation by equivalent circuits method. The predominance of mesopores in the electrode samples was confirmed by the functional density method. According to a scanning electron microscopy study, the surface morphology of the silicon-carbon films is highly developed due to the presence of three-dimensional agglomerates and "foliated" structures. The best retention of specific capacity after 450 charge/discharge cycles is observed for electrode samples containing manganese and nickel. Simulation of equivalent circuits showed that all types of electrodes have hierarchical pore structure. Ffter 450 charge/discharge cycles an increase in pore storage resistance and a decrease in transport pore resistance due to the activation of deeper pore levels is observed. The applicability of Peukert's law for the electrodes based on silicon-carbon films for prediction of electrode discharge time is shown. Keywords: Porous electrodes, silicon-carbon films, electrochemical impedance spectroscopy, equivalent circuit models, Peukert's law.