Measuring the capacitance of carbon in ionic liquids: From Graphite to Graphene

Robert Dryfe, Athanasios Papaderakis, Ji Soo Roh, Jing Yang, Mark Bissett, Radha Boya, Ashok Keerthi, Ralph Adams

Research output: Contribution to journalArticlepeer-review

Abstract

The physical electrochemistry of the carbon/ionic liquids interface underpins the processes occurring in a vast range of applications spanning electrochemical energy storage, iontronics devices and lubrication. Elucidating the charge storage mechanisms at the carbon/electrolyte interface will lead to a better understanding of the operational principles in such systems. Herein, we probe the charge stored at the electrochemical double layer formed between model carbon systems, ranging from single layer graphene to graphite and the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (EMIM-TFSI). The effect of the number of graphene layers on the overall capacitance of the interface is investigated. We demonstrate that in pure EMIM-TFSI and at moderate potential biases the electronic properties of graphene and graphite govern the overall capacitance of the interface, while the electrolyte contribution to the latter is less significant. In mixtures of EMIM-TFSI with solvents of varying relative permittivity, the complex interplay between electrolyte ions and solvent molecules is shown to influence the charged stored at the interface, which under certain conditions overcomes the effects of relative permittivity. This work provides additional experimental insights into the continuously advancing topic of the electrochemical double layer structure at the interface between room temperature ionic liquids and carbon materials.
Original languageEnglish
Pages (from-to)3674–3684
JournalThe Journal of Physical Chemistry Part C: Nanomaterials, Interfaces and Hard Matter
Volume128
Issue number9
Early online date21 Feb 2024
DOIs
Publication statusPublished - 7 Mar 2024

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