Effect of partial oxidation and repolarization of TiC-derived nanoporous carbon electrodes on supercapacitor performance using a pH-neutral aqueous electrolyte

• Published in: Journal of solid state electrochemistry Vol. 26; no. 11; pp. 2365 - 2378
• Main Authors: Käärik, Maike, Arulepp, Mati, Kozlova, Jekaterina, Aruväli, Jaan, Mäeorg, Uno, Kikas, Arvo, Kisand, Vambola, Tamm, Aile, Leis, Jaan
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2022; Springer Nature B.V
• Subjects: Analytical Chemistry; Aqueous electrolytes; Capacitance; Carbon; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Cycles; Electrochemical analysis; Electrochemical impedance spectroscopy; Electrochemistry; Electrode materials; Electrodes; Electrolytic cells; Energy Storage; Graphene; Infrared analysis; Original Paper; Oxidation; Photoelectrons; Physical Chemistry; Electrical double-layer capacitor; Aqueous electrolyte; Nanoporous carbon; pH neutral electrolyte; Carbide-derived carbon
• ISSN: 1432-8488; 1433-0768
• DOI: 10.1007/s10008-022-05253-4

The present study considers TiC-derived carbon (CDC) and its partially oxidized derivative (ox-red-CDC) as potential electrode materials for pH-neutral aqueous electrolytes. The CDC was converted to ox-red-CDC by a modified Hummers’ method involving back-reduction with hydrogen at 800 °C. Oxidation degraded the graphitic CDC structures, as shown by X-ray diffraction analysis, while scanning electron microscopy confirmed the exfoliation of graphene layers on the oxidized carbon surface. The changes in the surface chemistry of the carbon materials were studied by infrared, X-ray photoelectron, and energy-dispersive X-ray spectroscopy. The gas adsorption analysis showed a slight decrease in the volume of the subnanometer-sized pores during oxidation/reduction of CDC. To elucidate the relationships between the structure and electrochemical properties of carbon materials, cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy measurements were performed in 1 M Na 2 SO 4 using 2- and 3-electrode test cells. The highest capacitance of 163 F g −1 was demonstrated by pristine TiC-derived CDC in a symmetric 2-electrode cell. The asymmetric cell, which contained ox-red-CDC as an anode and pristine CDC as a cathode, had a slightly lower capacitance but an excellent cycling lifetime (specific capacitance increased by 7% after 5000 cycles). Temporary repolarization of 2-electrode cells during cycling improved both capacitance and power characteristics. Graphical abstract