Unveiling the ionic exchange mechanisms in vertically-oriented graphene nanosheet supercapacitor electrodes with electrochemical quartz crystal microbalance and ac-electrogravimetry

• Published in: Electrochemistry communications 2018-08, Vol.93, p.5-9
• Main Authors: Lé, T., Aradilla, D., Bidan, G., Billon, F., Delaunay, M., Gérard, J.M., Perrot, H., Sel, O.
• Format: Article
• Language: English
• Subjects: ac-electrogravimetry; Chemical Sciences; Graphene; Microbalance; Other; Supercapacitors
• ISSN: 1388-2481; 1873-1902
• DOI: 10.1016/j.elecom.2018.05.024

This work presents the first electrochemical quartz crystal microbalance (EQCM) results for vertically-oriented graphene nanosheets (VOGNs) as supercapacitor electrodes. Conventional EQCM technique delivered primary insights on the ionic exchange mechanisms between VOGNs and organic electrolytes, showing a major contribution of anions. A more advanced electrogravimetric methodology, ac-electrogravimetry, was then used to access specific dynamic attributes for each species exchanged at the VOGN electrode surface. Accordingly, under the conditions of this study, anions were confirmed to be the major energy storage vector with high kinetic values and low transfer resistance while cations and free solvent molecules are given non-negligible supporting roles. [Display omitted] •The mass of ions at the graphene surface is precisely measured in a varying potential.•BF4− anions exhibit a higher mobility than cations and are the main exchanged species.•Cyclic voltammetry mass variations were reconstructed using ac-electrogravimetry.