Unveiling the Ionic Exchange Mechanisms in Vertical Graphene Nanosheet Supercapacitor Electrodes by Using AC-Electrogravimetry
Abstract
Vertically oriented graphene nanosheets (VOGNs) have recently shown a great potential as
electrodes for electrochemical double layer capacitors due to their peculiar characteristics such
as high conductivity, ion access facility and open structure with high surface area [1, 2].
This work presents, for the first time, the electrochemical
quartz crystal microbalance (EQCM) results obtained on
VOGNs using various organic electrolytes. The
measurements were performed on VOGNs grown on goldpatterned GaPO4 piezoelectric resonator electrodes
according to our previous experimental conditions (Fig. 1a)
[2]. In this direction, EQCM measurements provide fruitful
insights derived from mass variations concerning the
behavior of ions upon cycling (Fig. 1b).
A more advanced electrogravimetric technique, acelectrogravimetry, combines electrochemical impedance
spectroscopy with mass measurements to obtain specific
dynamic attributes for each species exchanged at the
electrode surface (Fig. 1c).
This unique technique was used on VOGNs to attain the
deconvolution of the global EQCM outcome into
individual dynamic responses for each species exchanged
at the electrode-electrolyte interface [3]. Depending on the
nature of cations and anions, the energy storage mechanism
was driven by different species from the electrolyte. The
fundamental insight obtained in this study paves the way to
better understand the supercapacitor’s key mechanisms for
energy storage, which is crucial for further developing
new electrode designs.
References
[1] Z. Bo, S. Mao, Z.J. Han, K. Cen, J. Chen,
K.K. Ostrikov, Chem. Soc. Rev. 2015, 44, 2108–2121.
[2] D. Aradilla, M. Delaunay, S. Sadki, J.M. Gérard, G. Bidan, J. Mater. Chem. A. 2015,
3, 19254–19262.
[3] H. Goubaa, F. Escobar-Teran, I. Ressam, W. Gao, A.E. Kadib, I.T. Lucas, M.
Raihane, M. Lahcini, H. Perrot, O. Sel, J. Phys. Chem. C. 2017, 121, 9370–9380.