Issue 51, 2020

Resolving charge-transfer and mass-transfer processes of VO2+/VO2+ redox species across the electrode/electrolyte interface using electrochemical impedance spectroscopy for vanadium redox flow battery

Abstract

Electrochemical impedance spectroscopy is used to investigate the charge-transfer and mass-transfer processes of VO2+/VO2+ (V4+/V5+) redox species across the carbon-modified glassy carbon disk electrode/electrolyte interface. The features of the EIS patterns depend on the potential, concentrations of the redox species and mass-transport conditions at the electrode/electrolyte interface. With the starting electrolyte containing either only V4+ or V5+ redox species, EIS shows a straight line capacitor feature, as no oxidation or reduction reaction take place at the measured open circuit potential (OCP). With the electrolyte containing equimolar concentration of V4+ and V5+, EIS pattern has both charge-transfer and mass-transfer features at the equilibrium potential. The features of the charge-transfer process are observed to be influenced by the mass-transfer process. Optimum concentrations of the V4+/V5+ redox species and supporting H2SO4 electrolyte are required to resolve the EIS features corresponding to the underlying physical processes. The semi-infinite linear diffusion characteristics of the V4+/V5+ redox species observed with a static condition of the electrode converges to that of a finite diffusion under hydrodynamic condition.

Graphical abstract: Resolving charge-transfer and mass-transfer processes of VO2+/VO2+ redox species across the electrode/electrolyte interface using electrochemical impedance spectroscopy for vanadium redox flow battery

Supplementary files

Article information

Article type
Paper
Submitted
14 Jūn. 2020
Accepted
04 Aug. 2020
First published
20 Aug. 2020
This article is Open Access
Creative Commons BY license

RSC Adv., 2020,10, 30887-30895

Resolving charge-transfer and mass-transfer processes of VO2+/VO2+ redox species across the electrode/electrolyte interface using electrochemical impedance spectroscopy for vanadium redox flow battery

P. Leuaa, D. Priyadarshani, D. Choudhury, R. Maurya and M. Neergat, RSC Adv., 2020, 10, 30887 DOI: 10.1039/D0RA05224H

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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