Electrochemical Characterization of Single Layer Graphene/Electrolyte Interface: Effect of Solvent on the Interfacial Capacitance

Abstract

The development of the basic understanding of the charge storage mechanisms in electrodes for energy storage applications needs deep characterization of the electrode/ electrolyte interface. In this work, we studied the charge of the double layer capacitance at single layer graphene (SLG) electrode used as a model material, in neat (EMIm-TFSI) and solvated (with acetonitrile) ionic liquid electrodes. The combination of electrochemical impedance spectroscopy and gravimetric electrochemical quartz crystal microbalance (EQCM) measurements evidence that the presence of solvent drastically increases the charge carrier density at the SLG/ionic liquid interface. The capacitance is thus governed not only by the electronic properties of the graphene, but also by the specific organization of the electrolyte side at the SLG surface originating from the strong interactions existing between the EMIm + cations and SLG surface. EQCM measurements also show that the carbon structure, with the presence of sp 2 carbons, affects the charge storage mechanism by favoring counter-ion adsorption on SLG electrode versus ion exchange mechanism in amorphous porous carbons.

High Energy and Power Zinc Ion Capacitors: A Dual-Ion Adsorption and Reversible Chemical Adsorption Coupling Mechanism

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The electrochemical double layer at the graphene/aqueous electrolyte interface: what we can learn from simulations, experiments, and theory

“…More recently, however, there has been a renewed interest in more "fundamental" studies of the capacitance of graphene electrodes, with a focus on the effects of ion and substrate identity. For example, electrochemical impedance spectroscopy and quartz crystal microbalance methods have been confined to interrogate the double-layer formed with ionic liquids (either neat, or dissolved in acetonitrile) at monolayer graphene electrodes, prepared via CVD 102 . Specific adsorption of the imidazolium cation is the notable finding of this work, attributed to  interactions between the graphene and the cation.…”

Ion Dynamics at the Carbon Electrode/Electrolyte Interface: Influence of Carbon Nanotubes Types

“…In supercapacitors, the charge storage is based on a reversible adsorption of electrolyte ions towards the surface of electrodes [ 3 , 4 , 5 , 6 , 7 , 8 ]. Therefore, the selection of the electrode materials is important due to a certain number of parameters such as: specific surface area, porosity, structure, electrical conductivity, surface wettability, and electrochemical stability to improve the performance of electrodes [ 2 , 9 , 10 , 11 , 12 ].…”