The modified activated carbon treated with a low-temperature iodine plasma used as electrode material for electrochemical capacitors

• Low-temperature iodine plasma was used to modify the activated carbon material.
• Supercapacitors based on iodine-doped carbon showed an enhanced performance.
• Pseudocapacitance effect originates from iodine oxidation states.

This paper discusses a positive effect, of low-temperature plasma iodine treatment of activated carbon that could be used as electrode for electrochemical capacitor. The surface structure of the iodine-doped carbon tissue was examined using X-ray photoelectron spectroscopy (XPS). The surface area, and the carbon structure were characterized using gas adsorption method and observed by Scanning Electron Microscopy (SEM). The modified activated carbon material was used as electrode material of an electric double layer capacitor. The electrochemical characterization was carried out using cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. The electrochemical measurements confirmed an enhancement of the capacitance value after low-temperature iodine plasma treatment. The unusual behaviour of carbon/iodine interface is assumed to be related to redox activity of iodide-based species with various oxidation states from (−1) to (+5).

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