Electrochemical investigation of ionic liquid-derived porous carbon materials for supercapacitors: pseudocapacitance versus electrical double layer

• Published in: Electrochimica acta 2019-03, Vol.298 (C), p.541-551
• Main Authors: Zdolšek, Nikola, Rocha, Raquel P., Krstić, Jugoslav, Trtić-Petrović, Tatjana, Šljukić, Biljana, Figueiredo, José L., Vujković, Milica J.
• Format: Article
• Language: English
• Subjects: Aqueous electrolytes; Capacitance; Carbon; Carbon materials; Carbonization; Charge storage; Chemical composition; Electric double layer; Electrochemical analysis; Functional groups; Ionic liquids; Ions; Morphology; Organic chemistry; Porous materials; Pseudocapacitance; Supercapacitors; Surface layers; X ray photoelectron spectroscopy
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2018.12.129

This work shows the potential application of carbon materials prepared by three different ionic liquid-based methods, using 1-butyl-3-methylimidazolium methanesulfonate [bmim][MeSO3], for electrochemical supercapacitors. The effects of [bmim][MeSO3] on morphology, texture and surface chemistry of prepared materials has been explored by SEM/TEM, N2/CO2 adsorption measurements and XPS. The results indicate the possibility of synthesis of carbon materials with tunable physicochemical properties using ionic liquid based methods. The charge storage behavior of all materials was studied in three different pH aqueous electrolytes. The pseudocapacitive and double layer contributions were estimated and discussed from the aspect of the textural changes and the changes of the chemical composition of surface functional groups containing heteroatoms. CO type functional groups, with the contribution of COOH groups, were found to be responsible for a different amount of charge, which could be stored in alkaline and acidic electrolytic solution. The material prepared by direct carbonization of [bmim][MeSO3], showed the best electrochemical performance in alkaline electrolyte with a capacitance of 187 F g−1 at 5 mV s−1 (or 148 F g−1 at 1 A g−1), due to the contribution of both electric-double layer capacitance and pseudocapacitance which arises from oxygen, nitrogen and sulfur functional groups. [Display omitted] •Carbon materials were synthesized using new ionic liquid (IL) based methods.•Charge storage behavior in three pH-different electrolytes was compared.•Double layer and pseudocapacitance were separated and compared.•CO and COOH were found to be responsible for different charge storage.•Carbonized IL showed the highest capacitance due to contribution of N and S groups.