Understanding H₂-X redox flow battery performance through modeling and design of experiments
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Published version
Author(s)
Type
Journal Article
Abstract
This work investigates the impact of operating conditions on the performance of H₂-X redox flow battery (RFB),
using the H₂-V RFB as a case study. A lumped model incorporating electrochemical kinetics and membrane
water transport mechanisms was built and parameterized using polarization tests on a 25 cm2 cell under varying states of charge (SOC), temperatures and catholyte flow rates (𝑄v), following a full-factorial design of experiments. The effect of these conditions on voltage efficiency and discharge power density was analyzed. Results revealed that ohmic overpotential, driven by membrane dehydration, dominated total overpotentialeven at 100% relative humidity at the hydrogen inlet. This dehydration resulted from catholyte species uptake and water transport processes, exacerbated at high discharge current due to electro-osmotic drag driving water away from the gas side. Elevated operating temperatures mitigated dehydration, improving performance. At 1500 Am−2, 50% SOC and 70 mL min−1 𝑄v, increasing temperature from 24 to 40 ◦C improved peak power
density from 2325 to 3123 W m−2 and voltage efficiency from 81.3% to 85.1%. Avoiding operating the cell at 10% or lower SOC reduced ohmic overpotential associated with membrane resistance caused by higher catholyte species uptake at low SOC. At 1500 A m−2, 32 ◦C and 45 mL min−1 𝑄v, voltage efficiency increased from 80.7% to 82.9% as SOC was reduced from 90% to 50%, but dropped to 76.3% at 10% SOC. Catholyte flow rate had a smaller impact compared to temperature or SOC, primarily affecting concentration overpotential.
using the H₂-V RFB as a case study. A lumped model incorporating electrochemical kinetics and membrane
water transport mechanisms was built and parameterized using polarization tests on a 25 cm2 cell under varying states of charge (SOC), temperatures and catholyte flow rates (𝑄v), following a full-factorial design of experiments. The effect of these conditions on voltage efficiency and discharge power density was analyzed. Results revealed that ohmic overpotential, driven by membrane dehydration, dominated total overpotentialeven at 100% relative humidity at the hydrogen inlet. This dehydration resulted from catholyte species uptake and water transport processes, exacerbated at high discharge current due to electro-osmotic drag driving water away from the gas side. Elevated operating temperatures mitigated dehydration, improving performance. At 1500 Am−2, 50% SOC and 70 mL min−1 𝑄v, increasing temperature from 24 to 40 ◦C improved peak power
density from 2325 to 3123 W m−2 and voltage efficiency from 81.3% to 85.1%. Avoiding operating the cell at 10% or lower SOC reduced ohmic overpotential associated with membrane resistance caused by higher catholyte species uptake at low SOC. At 1500 A m−2, 32 ◦C and 45 mL min−1 𝑄v, voltage efficiency increased from 80.7% to 82.9% as SOC was reduced from 90% to 50%, but dropped to 76.3% at 10% SOC. Catholyte flow rate had a smaller impact compared to temperature or SOC, primarily affecting concentration overpotential.
Date Issued
2025-10-15
Date Acceptance
2025-07-14
Citation
Journal of Energy Storage, 2025, 132 (Part C)
ISSN
2352-152X
Publisher
Elsevier BV
Journal / Book Title
Journal of Energy Storage
Volume
132
Issue
Part C
Copyright Statement
© 2025 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
License URL
Publication Status
Published
Article Number
117765
Date Publish Online
2025-08-05