Dimerization of 9,10-anthraquinone-2,7-Disulfonic acid (AQDS)

Wiberg, Cedrik; Carney, Thomas J.; Brushett, Fikile R.; Ahlberg, Elisabet; Wang, Ergang

doi:10.1016/j.electacta.2019.05.134

Cited by 44 publications

(42 citation statements)

References 42 publications

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“…This could be rationalized by assuming that those bands were correlated to the interaction between AQDS and PI and the dimer formation reduces the interaction between AQDS and PI when the concentration of 2,7-AQDS and 2,7-AQDS 2À are comparable at the half-wave potential. [34,35] The dimer formation was also hinted in the pure 2,7-AQDS experiments in Figure 2 e, where nonmonotonous conversion at 1400-1600 cm À1 was observed. Besides these similarities, the band centered at about 3450 cm À1 showed a quite different response to CV scan compared to that at 3050 cm À1 (Figure 2 d), indicating that the two bands could be assigned to different hydrogen-bonded functional groups.…”

Section: Angewandte Chemiesupporting

confidence: 57%

“…The low molecule utilization was attributed to the pronounced dimerization when pH is shifted to > 12 after cycling, which might arise from the alkalinity of 2,7-AQDS itself and the hydroxyl products of dissolved oxygen in the first charging cycle. [21,34,35] Although the accessible concentration of 2,7-AQDS was low, the elongated plateaus after adding PI substantiates a reasonably high PI utilization of 66 % under 5 mA cm À2 , as shown in Figure 4 a. Loaded with more granules, the cell was tested for another 500 cycles at which the capacity decayed to 65 % of the initial value (Supporting Information, Figure S13). The long-term cycling along with the unchanged FTIR spectra of cycled PI granules (Supporting Information, Figure S14) show that the redox-targeting reaction and active material are reasonably stable.…”

Section: Zuschriftenmentioning

confidence: 81%

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Single‐Molecule Redox‐Targeting Reactions for a pH‐Neutral Aqueous Organic Redox Flow Battery

et al. 2020

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Aqueous organic redox flow batteries (AORFBs) have received considerable attention for large‐scale energy storage. Quinone derivatives, such as 9,10‐anthraquinone‐2,7‐disulphonic acid (2,7‐AQDS), have been explored intensively owing to potentially low cost and swift reaction kinetics. However, the low solubility in pH‐neutral electrolytes restricts their application to corrosive acidic or caustic systems. Herein, the single molecule redox‐targeting reactions of 2,7‐AQDS anolyte are presented to circumvent its solubility limit in pH‐neutral electrolytes. Polyimide was employed as a low‐cost high‐capacity solid material to boost the capacity of 2,7‐AQDS electrolyte to 97 Ah L−1. Through in situ FTIR spectroscopy, a hydrogen‐bonding mediated reaction mechanism was disclosed. In conjunction with NaI as catholyte and nickel hexacyanoferrate as the catholyte capacity booster, a single‐molecule redox‐targeting reaction‐based full cell with energy density up to 39 Wh L−1 was demonstrated.

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Section: Angewandte Chemiesupporting

confidence: 57%

Section: Zuschriftenmentioning

confidence: 81%

Single‐Molecule Redox‐Targeting Reactions for a pH‐Neutral Aqueous Organic Redox Flow Battery

et al. 2020

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“…Using bulk electrolysis in a stirred half-cell Carney et al [ 15 ] observed that an intermolecular dimerization of AQDS in acidic solution takes place at concentrations as low as 10 mmol dm −3 leading to decreased capacity utilization corresponding to 1.5 mol e – per mol AQDS. Recently, the formation of an electrochemically inactive dimer of the oxidized AQDS molecules was observed by Wiberg et al [ 16 ] significantly reducing the electrolyte utilization. According to Wermeckes et al [ 17 ] the degradation of unsubstituted AQ in an acidic environment consists of disproportionation of its 2e – reduced form (anthrahydroquinone, AQDSH 2 ) to anthraquinone and electrochemically inactive anthrone.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Electrochemical Stability of Sulfonated Anthraquinone-Based Acidic Electrolyte for Redox Flow Battery Application

Mazúr

Mrlík

et al. 2021

Molecules

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Despite intense research in the field of aqueous organic redox flow batteries, low molecular stability of electroactive compounds limits further commercialization. Additionally, currently used methods typically cannot differentiate between individual capacity fade mechanisms, such as degradation of electroactive compound and its cross-over through the membrane. We present a more complex method for in situ evaluation of (electro)chemical stability of electrolytes using a flow electrolyser and a double half-cell including permeation measurements of electrolyte cross-over through a membrane by a UV–VIS spectrometer. The method is employed to study (electro)chemical stability of acidic negolyte based on an anthraquinone sulfonation mixture containing mainly 2,6- and 2,7-anthraquinone disulfonic acid isomers, which can be directly used as an RFB negolyte. The effect of electrolyte state of charge (SoC), current load and operating temperature on electrolyte stability is tested. The results show enhanced capacity decay for fully charged electrolyte (0.9 and 2.45% per day at 20 °C and 40 °C, respectively) while very good stability is observed at 50% SoC and lower, even at 40 °C and under current load (0.02% per day). HPLC analysis conformed deep degradation of AQ derivatives connected with the loss of aromaticity. The developed method can be adopted for stability evaluation of electrolytes of various organic and inorganic RFB chemistries.

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“…NDI displayed reversible redox processes in both acidic and neutral pH at potentials appreciably below that of the archetypical ORFB candidate, 2,7‐AQDS, see Figure . Increasing the scan rate does not significantly change the reduction potentials for either the acid or neutral systems, indicating fast electron‐transfer kinetics.…”

Section: Resultsmentioning

confidence: 99%

“…A well‐performing flow battery with 9,10‐anthraquinone‐2,7‐disulfonic acid (AQDS) coupled with HBr/Br 2 was seminally demonstrated in 2014, and due to its fulfillment of many of the above criteria, AQDS has been thoroughly studied since and is often considered a model compound for aqueous ORFBs . However, AQDS in its oxidized form has been shown to self‐associate in solution, forming a redox‐inactive dimer that somewhat impedes its use in electrochemical applications …”

Section: Introductionmentioning

confidence: 99%

Electrochemical Evaluation of a Napthalene Diimide Derivative for Potential Application in Aqueous Organic Redox Flow Batteries

et al. 2019

Self Cite

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A quaternary amine‐functionalized naphthalene diimide (NDI) moiety is synthesized and considered as a redox‐active species for application in aqueous organic redox flow batteries. For the first time, this NDI is characterized electrochemically in aqueous solutions, using cyclic and rotating disk electrode voltammetry, bulk electrolysis, as well as 1H‐nuclear magnetic resonance (1H‐NMR) spectroscopy. The molecule reaches a solubility of 0.68 m in water and reversibly delivers two electrons at attractive potentials for flow battery applications. Further exploration with 1H‐NMR reveals a strong dimerization of the NDI species with an equilibrium constant of 146 m−1. Using diffusion NMR coupled with rotating disk electrode voltammetry, it is shown that the dimer retains limited redox‐activity, yielding two electrons per dimer unit. However, using galvanostatic bulk electrolysis, close to the theoretical capacity is obtained, indicating a fast dissociation reaction of the reduced dimer. Finally, the NDI species shows excellent stability; after constant cycling for 1 week, no degradation is detected. In conclusion, NDI is demonstrated to be a highly attractive candidate for aqueous redox flow batteries.

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Dimerization of 9,10-anthraquinone-2,7-Disulfonic acid (AQDS)

Cited by 44 publications

References 42 publications

Single‐Molecule Redox‐Targeting Reactions for a pH‐Neutral Aqueous Organic Redox Flow Battery

Single‐Molecule Redox‐Targeting Reactions for a pH‐Neutral Aqueous Organic Redox Flow Battery

Evaluation of Electrochemical Stability of Sulfonated Anthraquinone-Based Acidic Electrolyte for Redox Flow Battery Application

Electrochemical Evaluation of a Napthalene Diimide Derivative for Potential Application in Aqueous Organic Redox Flow Batteries

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