In this work, the perovskite LaMnO3 material has been prepared based on the sol-gel process of synthesis with the participation of combustion. According to the X-ray phase analysis, it was determined that the obtained material consists of LaMnO3 one phase (space group Pm-3m). Nevertheless, it has been determined that the average size of the coherent scattering region of the obtained material is about 24 nm. Moreover, the average particle size is 40-60 nm in case the approximation that the particles are spherical shape. Thus, it has been determined that the specific surface area of the material is 42.1 m2/g. The electrochemical investigations have been performed using nanosized LaMnO3 powder as a cathode material for electrochemical capacitors. The LaMnO3 material under research showed a specific capacity of 40 F/g at a discharge of up to 1V.

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In this work, the electrochemical behavior of LaMnO3 perovskite material and nanoporous carbon material in an aqueous solution of lithium sulfate are studied. The regularities of the expediency of the joint functioning of these materials as electrodes for a hybrid electrochemical capacitor are determined. It was found that the value of the specific capacity of the investigated electrochemical system of LaMnO3 / electrolyte / AC is 52 F/g during the discharge of the system to 1 V and the value of specific energy is 112.1 J /g at a discharge current of 1 mA.

In this study, the α and β modifications of MnO2 have been successfully synthesized by the hydrothermal method. The obtained materials have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and low-temperature nitrogen adsorption. In addition, the supercapacitor performance of the materials has been pre-tested to assess their suitability for practical applications. The average particle size of the α modification is 12-15 nm, and the β modification is 14-18 nm. The surface areas of the α and β modifications of MnO2 are 200 m2/g and 70 m2/g, respectively. The average pore sizes are 3.2 nm and 5.3 nm, respectively. The specific capacitance of 40 F/g is observed at 1 mV/s, which has been recorded using cyclic voltammetry and constant current charge-discharge cycling in 30 % aqueous KOH solutions. It has been determined that the specific capacitance of the β - MnO2/electrolyte system decreases from 40 F/g to 15 F/g with an increase in the scan rate from 1 to 30 mV/s. In addition, the total capacitance of the material was divided into the electric double layer capacitance and the diffusion-controlled redox capacitance due to the Faraday reverse redox reactions. Finally, the pseudocapacitance contribution has been determined to be 90 % of the total specific capacitance.