Synthesis and Electrochemical Properties of Mesoporous α-MnO2 for Supercapacitor Applications

Authors P.I. Kolkovskyi, B.I. Rachiy , M.I. Kolkovskyi, B.K. Ostafiychuk , I.P. Yaremiy , V.O. Kotsyubynsky , R.V. Ilnitsky

Vasyl Stefanyk Precarpathian National University, 57, Shevchenko St., 76018 Ivano-Frankivsk, Ukraine

Issue Volume 12, Year 2020, Number 3
Dates Received 03 March 2020; revised manuscript received 15 June 2020; published online 25 June 2020
Citation P.I. Kolkovskyi, B.I. Rachiy, M.I. Kolkovskyi, et al., J. Nano- Electron. Phys. 12 No 3, 03030 (2020)
PACS Number(s) 61.43.Gt, 68.43.Bc
Keywords Manganese oxide, Pseudocapacity, Hybrid electrochemical capacitor, KOH.       .

In this work, the crystal structure of alpha-MnO2 has been obtained by the hydrothermal method. It was determined that the obtained material has a tunnel structure with average particle sizes of 12-15 nm. The electrochemical performances of α-MnO2 in an aqueous solution of 30 % KOH based electrolyte have been investigated by cyclic voltammetry and galvanostatic cycling methods. At the same time, it was determined that the specific capacity of the α-MnO2/electrolyte system decreased from 90 F/g to 55 F/g with an increase of the scan rate from 2 to 10 mV/s. Thus, the maximum values of specific capacitance about 104 F/g were obtained at 0.5 mV/s. The Coulomb efficiency of the electrochemical system is constant and independent of the cycle number under the charge/discharge process. Therefore, the total capacity of the material under investigation can be divided into the capacity of the double electric layer and the diffusion-controlled redox capacity due to the Faraday reverse redox reactions. It was determined that the contribution of pseudocapacity is 90 % of the total specific capacity. In addition, it has been determined that the α-MnO2/KOH electrochemical system is stable under long-term cycling process.

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