Effects of Oxygen-Containing Functional Groups on the Electrochemical Performance of Activated Carbon for EDLCs

• Published in: Nanomaterials (Basel, Switzerland) Vol. 13; no. 2; p. 262
• Main Authors: Kim, Ju-Hwan, Kim, Seok-Hwi, Kim, Byung-Joo, Lee, Hye-Min
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 07.01.2023; MDPI
• Subjects: Activated carbon; Atmosphere; Atmospheres; Capacitance; EDLCs; electric double-layer capacitors; Electrochemical analysis; Electrochemistry; Electrodes; Electrolytes; Energy; Functional groups; Gases; Heat; Heat treatment; Heat treatments; Hydrogen; Life span; Nitrogen; Oxidation; Oxygen; oxygen functional groups; Photoelectron spectroscopy; Photoelectrons; Reduction; Surface chemistry; United States > US; Japan; electric double-layer capacitors; EDLCs; activated carbon; oxygen functional groups
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano13020262

Activated carbon (AC) is used in commercial electric double-layer capacitors (EDLC) as electrode active material owing to its favorable properties. However, oxygen functional groups (OFGs) present in AC reduce the lifespan of EDLCs. Thus, we investigated the correlation between the OFGs in AC and their electrochemical characteristics. Samples were prepared by heat-treating commercial AC at 300 °C-900 °C for 1 h under two gas atmospheres (N and 4% H /N mixed gas). The textural properties were studied, and the reduction characteristics of AC under Ar and H /Ar mixed gas atmospheres were investigated. Additionally, changes in the OFGs with respect to the heat-treatment conditions were examined via X-ray photoelectron spectroscopy. The specific surface areas of AC-N and AC-H were 2220-2040 and 2220-2090 m /g, respectively. Importantly, the samples treated in hydrogen gas exhibited a higher yield than those treated in nitrogen while maintaining their pore characteristics. Additionally, the electrochemical performance of the AC was significantly enhanced after the reduction process; the specific capacitance increased from 62.1 F/g to 81.6 F/g (at 0.1 A/g). Thus, heat treatment in hydrogen gas improves the electrochemical performance of EDLCs without destroying the pore characteristics of AC.