A series of ionic liquids containing imidazolium, pyrrolidinium, or ether-functionalized pyrrolidinium cations incorporated with the same counter anion of bis(fluorosulfonyl)imide (FSI−) were synthesized to investigate the effects of the cation structures on the physical and electrochemical properties of ionic liquids. The introduction of the polar ether group was able to compensate for the loss of the mobility of pyrrolidinium cation-based ionic liquids, while maintaining the high thermal and electrochemical stability. Extensive examinations of these ionic liquids in electric double-layer capacitor (EDLC) cells were performed to investigate their voltage stability under various operating conditions. Electrochemical evaluation revealed that the cell fabricated with ether-functionalized pyrrolidinium ionic liquid could deliver larger capacitance values and stable cycling performance compared with the cell containing imidazolium-based ionic liquid at high operating voltage; demonstrating its possible applications as high voltage electrolytes for EDLCs.
Bibliographical noteFunding Information:
This work was financially supported by grants from the Fundamental R&D Program for Core Technology of Materials and Industrial Strategic Technology Development Program funded by the Ministry of Knowledge Economy, Republic of Korea. Partial funding was given by the Materials Architecturing Research Center of Korea Institute of Science and Technology (KIST) and the Korea Research Fellowship Program funded by the Ministry of Science, ICT, and Future Planning through the National Research Foundation of Korea. We would also like to give special thanks to In-hyuk Lee for valuable and sincere discussions about the experimental methods and data.
© 2016 Elsevier Ltd
- Electrical double-layer capacitor
- High operating voltage
- Ionic liquid
ASJC Scopus subject areas
- General Chemical Engineering