Enhancing the Electrochemical Performance of ZnO-Co3O4 and Zn-Co-O Supercapacitor Electrodes Due to the In Situ Electrochemical Etching Process and the Formation of Co3O4 Nanoparticles
Abdullin K. Gabdullin M. Kalkozova Z. Kudryashov V. Mirzaeian M. Yelemessov K. Baskanbayeva D. Serikkanov A.
April 2024Multidisciplinary Digital Publishing Institute (MDPI)
Energies
2024#17Issue 8
Zinc oxide (ZnO) and materials based on it are often used to create battery-type supercapacitor electrodes and are considered as promising materials for hybrid asymmetric supercapacitors. However, when creating such electrodes, it is necessary to take into account the instability and degradation of zinc oxide in aggressive environments with a non-neutral pH. To the best of our knowledge, studies of the changes in the properties of ZnO-containing electrodes in alkaline electrolytes have not been carried out. In this work, changes in the structure and properties of these electrodes under alkaline treatment were investigated using the example of ZnO-containing composites, which are often used for the manufacturing of supercapacitor electrodes. Supercapacitor electrodes made of two materials containing ZnO were studied: (i) a heterogeneous ZnO-Co3O4 system, and (ii) a hexagonal h-Zn-Co-O solid solution. A comparison was made between the structure and properties of these materials before and after in situ electrochemical oxidation in the process of measuring cyclic voltammetry and galvanostatic charge/discharge. It has been shown that the structure of both nanoparticles of the heterogeneous ZnO-Co3O4 system and the h-Zn-Co-O solid solution changes due to the dissolution of ZnO in the alkaline electrolyte 3.5 M KOH, with the short-term alkaline treatment producing cobalt and zinc hydroxides, and long-term exposure leading to electrochemical cyclic oxidation–reduction, forming cobalt oxide Co3O4. Since the resulting cobalt oxide nanoparticles are immobilized in the electrode structure, a considerable specific capacity of 446 F g−1 or 74.4 mA h g−1 is achieved at a mass loading of 0.0105 g. The fabricated hybrid capacitor showed a good electrochemical performance, with a series resistance of 0.2 Ohm and a capacitance retention of 87% after 10,000 cycles.
cobalt oxide nanoparticles , supercapacitor electrode , ZnO-based composite
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National Nanotechnology Laboratory of Open Type (NNLOT), Al-Farabi Kazakh National University, Al-Farabi Avenue 71, Almaty, 050040, Kazakhstan
Satbayev University, Institute of Physics and Technology, Almaty, 050013, Kazakhstan
Kazakh-British Technical University, Tole bi Street, 59, Almaty, 050000, Kazakhstan
Lab of Renewable Energy, National Laboratory Astana, Nazarbayev University, Astana, 010000, Kazakhstan
School of Computing, Engineering and Physical Sciences, University of the West of Scotland, Paisley, PA1 2BE, United Kingdom
Institute of Energy and Mechanical Engineering named after A. Burkitbayev, Satbayev University, 22 Satbaev Str., Almaty, 050013, Kazakhstan
National Academy of Sciences of the Republic of Kazakhstan under the President of the Republic of Kazakhstan, Shevchenko Str. 28, Almaty, 050010, Kazakhstan
National Nanotechnology Laboratory of Open Type (NNLOT)
Satbayev University
Kazakh-British Technical University
Lab of Renewable Energy
School of Computing
Institute of Energy and Mechanical Engineering named after A. Burkitbayev
National Academy of Sciences of the Republic of Kazakhstan under the President of the Republic of Kazakhstan
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