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Electrochemical stability of selected quinone and viologen derivatives for organic electrolyte based redox flow battery.

Authors: Mazur Petr | Mrlík Jindřich | Kvíčala Jaroslav | Hloušková Zuzana | Klikar Milan | Bureš Filip | Akrman Jiří | Kubáč Luboš

Year: 2019

Type of publication: ostatní - přednáška nebo poster

Page from-to: nestránkováno

Titles:

Language	Name	Abstract	Keywords
eng	Electrochemical stability of selected quinone and viologen derivatives for organic electrolyte based redox flow battery.	First part of the study aims to identify promising EAC for application in RFB. Three main groups of organic redox compounds are being thoroughly investigated: i) conjugated compounds with carbonyl functional group (quinones etc.); ii) nitrogen containing heteroaromatics (pyridine, bipyridine etc.) and iii) organometallic (mainly ferrocenes). Bipyridine derivatives exhibited promising two-step two-electron quasireversible reactions around -1.1 V vs. SHE in neutral electrolyte. Subsequent half-cell testing, however, revealed insufficient electrochemical stability of both partially and fully reduced forms (most likely due to dimerization leading to adsorption and deactivation of electrode surface). Further structural modification of the molecule was studied to prevent these negative phenomena, e.g., by addition of solubilizing groups in order to increase solubility and prevent dimerization. The main bipyridine skeleton was further modified by different electron-withdrawing and electron-donating groups. In the second part of the contribution, the electrochemical stability of selected sulphonated anthraquinones is systematically studied on single-cell level. Acidic electrolyte based on 2,7-anthraquinone-disulfonic acid (2,7-AQDS) shows stable half-cell parameters (load curve, EIS spectra, cycle efficiencies) for over 300 charge-discharge cycles at 200 mA cm-2. Moreover, no detectable permeation of 2,7-AQDS through commercial PFSA membrane was observed which correlates well with excellent coulombic efficiency (99.9 %) and negligible decrease of discharge capacity (0.02 % of initial capacity per cycle). Subsequent testing in symmetric-electrolyte and single-electrolyte set-ups is undertaken to deeply investigate the electrochemical stability of the compound and the inner cell components under different conditions (SoC, current load, temperature etc.).	quinone; viologen; redox flow battery; electrochemical