Towards understanding the impact of operating voltage on the stability of adiponitrile-based electrical double-layer capacitors

• Published in: Journal of power sources 2021-06, Vol.496, p.229841, Article 229841
• Main Authors: Bothe, A., Pourhosseini, S.E.M., Ratajczak, P., Beguin, F., Balducci, A.
• Format: Article
• Language: English
• Subjects: Adiponitrile; EDLCs; Gas adsorption; High voltage; Temperature programmed desorption
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2021.229841

In this work, we report about the impact of operating voltage on the electrochemical performance of carbon-based electrical double-layer capacitors (EDLCs) containing 1.75 mol L−1 1-butyl-1-methylpyrrolidinium tetrafluoroborate (Pyr14BF4) in adiponitrile (ADN) as electrolytic medium. The stability of EDLCs containing this electrolyte has been investigated at maximum voltage ranging from 3.0 V to 3.7 V at room temperature (RT) and at 60 °C. At RT, the devices displayed remarkable cycling stability, and after 100,000 galvanostatic charge discharge cycles (at 5 A g−1) up to 3.7 V they retained 81% of their initial capacitance. After 10,000 galvanostatic charge discharge cycles (at 5 A g−1) up to 3.4 V and 60 °C the EDLCs displayed a capacitance retention of 83%. After 300 h of floating at 3.0 V the cells kept 80% of their initial capacitance. Post-mortem experiments by gas adsorption and temperature programmed desorption (TPD) on the aged electrodes revealed that after long-term operation, the porous texture and surface chemistry of the positive electrode is more affected than the negative one. The results of this study reveal that 1.75 mol L−1 Pyr14BF4 in ADN is a promising electrolyte for the realization of high voltage EDLCs. •1.75 mol L−1 Pyr14BF4 in AND is a promising electrolyte for high voltage EDLCs.•ADN-based EDLCs display high stability at high operating voltage.•TPD is a powerful technique to investigate the electrode aging.