Electrochemistry
Online ISSN : 2186-2451
Print ISSN : 1344-3542
ISSN-L : 1344-3542
Articles
Confinement Effects on the Rate Performance of Redox Active Molecules for Pseudocapacitive Flowable Electrodes
Daisuke TAKIMOTO Keisuke SUZUKISho HIDESHIMAWataru SUGIMOTO
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2023 Volume 91 Issue 4 Pages 047005

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Abstract

The pseudocapacitive flowable electrodes typically show high energy density because of the contribution of the faradaic charge of redox-active organic materials and the electric double layer charge of carbon materials. However, the redox reaction kinetics of organic molecules are slow due to poor diffusion kinetics. We recently reported that a pseudocapacitive flowable electrode exhibited bell-shaped cyclic voltammograms (peak separation (ΔEp) = 0 mV); specifically, the molecules were confined within slit-shaped graphitic micropores of activated carbon (AC). Herein, we studied the relationship between charge storage and the reaction mechanism to tailor the electrochemical performance of a pseudocapacitive flowable electrode by half-cell study. The results show that the redox reaction of the confined molecules entailed a charge-transfer-controlled mechanism, while the unconfined molecules exhibited a mass-transfer-controlled system. This difference inhibited the fast charging and discharging of the pseudocapacitive flowable electrode. This study demonstrates that half-cell studies are crucial for clarifying the relationship between the charge storage and rate performances of pseudocapacitive flowable electrodes.

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© The Author(s) 2023. Published by ECSJ.

This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License (CC BY-NC-SA, http://creativecommons.org/licenses/by-nc-sa/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium by share-alike, provided the original work is properly cited. For permission for commercial reuse, please email to the corresponding author. [DOI: 10.5796/electrochemistry.23-00024].
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