Open circuit voltage of vanadium redox flow batteries: Discrepancy between models and experiments
By K. Knehr, E. C. Kumbur. 2011
220 citations recorded by the source corpus.
A major issue with the existing vanadium redox flow battery (VRFB) models is the inaccurate prediction of the open circuit voltage (OCV), which results in a discrepancy of 131 to 140 mV in predicted cell voltages when compared to experimental data. This deviation is shown to be caused by the incomplete description of the electrochemical double layers within the cell when calculating the OCV using the Nernst equation adopted from fuel cell literature. Here, we propose a more complete description of the Nernst equation, which accounts for two additional electrochemical mechanisms that exist in a VRFB, namely: i) the proton activity at the positive electrode due to the involvement of the protons in the redox reaction, and ii) the Donnan potential due to the proton concentration differences across the membrane. The complete form of the Nernst equation proposed herein accurately predicts the reported experimental data with an average error of 1.2%, showing a significant improvement over the incomplete Nernst equation (8.1% average error) currently used in VRFB models.
Subfields: Automotive Engineering, Electrical and Electronic Engineering, Renewable Energy, Sustainability and the Environment
View Paper: https://www.semanticscholar.org/paper/1a9021bc0b6b6cecd2ac9a812429c520e70abb8e
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In Automotive Engineering
In Electrical and Electronic Engineering
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Citations in the corpus
- A review of all‐vanadium redox flow battery durability: Degradation mechanisms and mitigation strategies (2019, background): “In a VRFB cell, the potential difference is approximately 1.4 V, which may electrolyze water into oxygen and hydrogen (Equations 15 ‐ 16) during the VRFB operation.”
- Techno-Economic Modeling and Analysis of Redox Flow Battery Systems (2016, methodology): “The theoretical value of the standard potential differences was used as the reversible cell voltage, although the actual value can be higher due to membrane potentials [12].”
- Redox flow batteries: Status and perspective towards sustainable stationary energy storage (2021, background): “The electrochemical half-reactions produced by these solutions in the cells are: The corresponding standard cell voltage is E 0 = 1.26 V at 25 ◦ C and 50% SoC, but real cells exhibit E 0 ’ = 1.4 V, due to side effects, mainly the Donnan potential appearing at the membrane surfaces [13].”