Redox Flow Batteries: How to Determine Electrochemical Kinetic Parameters

Wang, H; Sayed, Sayed Youssef; Luber, Erik J.; Olsen, Brian C.; Shirurkar, Shubham M.; Venkatakrishnan, Sankaranarayanan; Tefashe, Ushula M.; Farquhar, Anna K.; Smotkin, Eugene S.; McCreery, Richard L.; Buriak, Jillian M.

doi:10.1021/acsnano.0c01281

Cited by 153 publications

(126 citation statements)

References 44 publications

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“…From Fig. 3c and d, an increase in ΔEp with increasing scan rate can be found, which is consistent with many studies showing that the redox reaction of vanadium ions on the electrode is a quasi-reversible reaction [51][52][53] . As the scan rate increases, ΔEp increases because a larger overpotential is required due to the enhanced polarization effect, which suggests that the reaction kinetics come into competition with mass transfer.…”

Section: Electrochemical Properties Of Electrolytessupporting

confidence: 90%

Molybdenum-assisted reduction of VO2+ for low cost electrolytes of vanadium redox flow batteries

Hwang¹,

Ha²,

Park³

2021

Preprint

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Efficient and affordable energy storage systems are indispensable to accomplish a successful energy transition from fossil fuels to renewable sources. Although all-vanadium redox flow batteries (VRFB) possess many distinctive advantages, much improvement in the process for electrolyte preparation is needed to overcome low productivity and complexity of the current electrolysis process. Herein, we demonstrate a simple one-pot process for the preparation of V3.5+ electrolytes from V2O5 by utilizing hydrazine monohydrate as a residue-free reducing agent and molybdenum as a homogeneous catalyst accelerating the reduction of VO2+. It is confirmed that the performance of the electrolytes prepared by the newly developed process is identical to that by electrolysis in terms of charge-discharge efficiency and capacity up to current density of 200 mA cm-2. This study can contribute to the wide spread of VRFB by providing a scalable process suitable for the mass production of V3.5+ electrolyte.

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Section: Electrochemical Properties Of Electrolytessupporting

confidence: 90%

Molybdenum-assisted reduction of VO2+ for low cost electrolytes of vanadium redox flow batteries

Hwang¹,

Ha²,

Park³

2021

Preprint

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“…Excess catholyte is used to ensure complete electrochemical reaction of AzoPh in the anolyte side. The open‐circuit voltage (OCV) of a RFB is dictated by the state of charge (SOC) and the potential of the redox couples [2c,32] . The OCV of the AzoPh/PEG3‐PTZ battery rapidly increases with SOCs ranging from 10 % to 30 %, and a potential plateau was observed at 2.05 V in the SOC range of 30 %∼100 % (Figure 3a), corresponding to the redox couples of AzoPh − /AzoPh 0 (−1.69 V vs. Ag/Ag + ) and PEG3‐PTZ 0 /PEG3‐PTZ + (−0.39 V vs. Ag/Ag + ).…”

Section: Resultsmentioning

confidence: 99%

Azobenzene‐Based Low‐Potential Anolyte for Nonaqueous Organic Redox Flow Batteries

et al. 2020

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Redox flow batteries (RFBs) using organic materials in organic solvents are particularly promising because of the diversity of organic materials and the wide redox‐innocent window of organic solvents, yet the further development of this type of RFB has been hindered by the lack of suitable anolyte materials with high potentials, solubility, and stability. Herein, we examine the physical and electrochemical properties of azobenzene (AzoPh) compounds and investigate their degradation mechanism in nonaqueous organic RFB. The azobenzene displayed two‐electron activity at −1.69 and −2.20 V vs. Ag/Ag+. Paired with a well‐established PEGylated phenothiazine (PEG3‐PTZ ) catholyte, the battery presents a high theoretical cell voltage of 2.08 V. The azobenzene‐based RFB displays a capacity retention of 93.3 % over 50 cycles with an average fade rate of 0.13 % per cycle. The capacity decay mechanism was probed by proton nuclear magnetic resonance spectroscopy, cyclic voltammetry, and high‐resolution mass spectrometry, and revealed proton‐assisted degradation mechanisms.

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“…Cathode catalysts are usually chosen from platinum group metals, as these elements are all active as hydrogenation catalysts [6,[13][14][15]21,[40][41][42][43][44][45][46][47]. Their utility is limited when the supporting electrolyte is aqueous because they are also active for reducing water (to make H 2 ).…”

Section: Choosing/designing Electrocatalysts For Organic Redox Flow Bmentioning

confidence: 99%

Electrocatalysts for Using Renewably-Sourced, Organic Electrolytes for Redox Flow Batteries

Weber

2021

Catalysts

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Biomass could be a source of the redox shuttles that have shown promise for operation as high potential, organic electrolytes for redox flow batteries. There is a sufficient quantity of biomass to satisfy the growing demand to buffer the episodic nature of renewably produced electricity. However, despite a century of effort, it is still not evident how to use existing information from organic electrochemistry to design the electrocatalysts or supporting electrolytes that will confer the required activity, selectivity and longevity. In this research, the use of a fiducial reaction to normalize reaction rates is shown to fail.

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Redox Flow Batteries: How to Determine Electrochemical Kinetic Parameters

Cited by 153 publications

References 44 publications

Molybdenum-assisted reduction of VO2+ for low cost electrolytes of vanadium redox flow batteries

Molybdenum-assisted reduction of VO2+ for low cost electrolytes of vanadium redox flow batteries

Azobenzene‐Based Low‐Potential Anolyte for Nonaqueous Organic Redox Flow Batteries

Electrocatalysts for Using Renewably-Sourced, Organic Electrolytes for Redox Flow Batteries

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