Mass Transport Optimization for Redox Flow Battery Design

The world is moving to the next phase of the energy transition with high penetrations of renewable energy. Flexible and scalable redox flow battery (RFB) technology is expected to play an important role in ensuring electricity network security and reliability. Continuous performance improvements will further enhance their value by reducing parasitic losses and maximizing available energy conversion over broader operating conditions. Concentration overpotentials from poor internal reactant distribution at high and low states of charge (SOC) limit power densities and are thus an important area of investigation. However, efforts to address these coupled electrochemical phenomena can compromise mechanical performance. Modelling and simulation of cell design innovations have shown it is possible to reduce losses from pump energy while increasing the availability of active species where required. The combination of wedge-shaped cells with static mixers investigated in this paper can reduce pressure drop and improve energy efficiency. Toroidal vanadium redox flow battery (VRB/VRFB) designs incorporating this innovation are presented for further development to improve community engagement with the technology.

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Mass Transport Optimization for Redox Flow Battery Design

Applied Sciences ◽

10.3390/app10082801 ◽

2020 ◽

Vol 10 (8) ◽

pp. 2801 ◽

Cited By ~ 4

Author(s):

Nicholas Gurieff ◽

Declan Finn Keogh ◽

Mark Baldry ◽

Victoria Timchenko ◽

Donna Green ◽

...

Keyword(s):

Computer Aided Design ◽

Pump Energy ◽

Energy Transition ◽

Active Species ◽

Operating Conditions ◽

Vanadium Redox Flow Battery ◽

Redox Flow Battery ◽

Flow Battery ◽

Charge Voltage ◽

Available Energy

The world is moving to the next phase of the energy transition with high penetrations of renewable energy. Flexible and scalable redox flow battery (RFB) technology is expected to play an important role in ensuring electricity network security and reliability. Innovations continue to enhance their value by reducing parasitic losses and maximizing available energy over broader operating conditions. Simulations of vanadium redox flow battery (VRB/VRFB) cells were conducted using a validated COMSOL Multiphysics model. Cell designs are developed to reduce losses from pump energy while improving the delivery of active species where required. The combination of wedge-shaped cells with static mixers is found to improve performance by reducing differential pressure and concentration overpotential. Higher electrode compression at the outlet optimises material properties through the cell, while the mixer mitigates concentration gradients across the cell. Simulations show a 12% lower pressure drop across the cell and a 2% lower charge voltage for improved energy efficiency. Wedge-shaped cells are shown to offer extended capacity during cycling. The prototype mixers are fabricated using additive manufacturing for further studies. Toroidal battery designs incorporating these innovations at the kW scale are developed through inter-disciplinary collaboration and rendered using computer aided design (CAD).

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Cerium/Ascorbic Acid/Iodine Active Species for Redox Flow Energy Storage Battery

Molecules ◽

10.3390/molecules26113443 ◽

2021 ◽

Vol 26 (11) ◽

pp. 3443

Author(s):

Tzu-Chin Chang ◽

Yu-Hsuan Liu ◽

Mei-Ling Chen ◽

Chen-Chen Tseng ◽

Yung-Sheng Lin ◽

...

Keyword(s):

Ascorbic Acid ◽

Composite Electrode ◽

Active Species ◽

Ion Pair ◽

Vanadium Redox Flow Battery ◽

Carbon Paper ◽

Nitrate Hexahydrate ◽

Redox Flow Battery ◽

Flow Battery ◽

Oxidation Reduction

In this study, we developed a novel cerium/ascorbic acid/iodine active species to design a redox flow battery (RFB), in which the cerium nitrate hexahydrate [Ce(NO3)3·6H2O] was used as a positive Ce3+/Ce4+ ion pair, and the potassium iodate (KIO3) containing ascorbic acid was used as a negative I2/I− ion pair. In order to improve the electrochemical activity and to avoid cross-contamination of the redox pair ions, the electroless plating and sol–gel method were applied to modify the carbon paper electrode and the Nafion 117 membrane. The electrocatalytic and electrochemical properties of the composite electrode using methanesulfonic acid as a supporting electrolyte were assessed using the cyclic voltammetry (CV) test. The results showed that the Ce (III)/Ce (IV) active species presented a symmetric oxidation/reduction current ratio (1.09) on the C–TiO2–PdO composite electrode. Adding a constant amount of ascorbic acid to the iodine solution led to a good reversible oxidation/reduction reaction. Therefore, a novel Ce/ascorbic acid/I RFB was developed with C–TiO2–PdO composite electrodes and modified Nafion 117–SiO2–SO3H membrane using the staggered-type flow channel, of which the energy efficiency (EE%) can reach about 72%. The Ce/ascorbic acid/I active species can greatly reduce the electrolyte cost compared to the all-vanadium redox flow battery system, and it therefore has greater development potential.

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Mitigating capacity decay and improving charge-discharge performance of a vanadium redox flow battery with asymmetric operating conditions

Electrochimica Acta ◽

10.1016/j.electacta.2019.04.032 ◽

2019 ◽

Vol 309 ◽

pp. 283-299 ◽

Cited By ~ 6

Author(s):

M.Y. Lu ◽

W.W. Yang ◽

Y.M. Deng ◽

W.Z. Li ◽

Q. Xu ◽

...

Keyword(s):

Operating Conditions ◽

Vanadium Redox Flow Battery ◽

Redox Flow Battery ◽

Flow Battery ◽

Discharge Performance ◽

Vanadium Redox ◽

Charge Discharge ◽

Capacity Decay

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Dynamic Model of a Vanadium Redox Flow Battery for System Performance Control

Journal of Solar Energy Engineering ◽

10.1115/1.4024928 ◽

2013 ◽

Vol 136 (2) ◽

Cited By ~ 8

Author(s):

Victor Yu ◽

Dongmei Chen

Keyword(s):

Mass Transfer ◽

System Performance ◽

Operating Cost ◽

Operating Conditions ◽

Vanadium Redox Flow Battery ◽

Electrochemical Kinetics ◽

Voltage Response ◽

Redox Flow Battery ◽

Flow Battery ◽

Vanadium Redox

The vanadium redox flow battery (VRFB) is an attractive grid scale energy storage option, but high operating cost prevents widespread commercialization. One way of mitigating cost is to optimize system performance, which requires an accurate model capable of predicting cell voltage under different operating conditions such as current, temperature, flow rate, and state of charge. This paper presents a lumped isothermal VRFB model based on principles of mass transfer and electrochemical kinetics that can predict transient performance with respect to the aforementioned operating conditions. The model captures two important physical phenomena: (1) mass transfer at the electrode surface and (2) vanadium crossover through the membrane. Mass transfer effects increase the overpotential and thus reduce the battery output voltage during discharge. Vanadium crossover causes a concentration imbalance between the two half-cells that negatively affects the voltage response particularly after long term cycling. Further analysis on the system linearity is conducted to assess the feasibility of using a linear control design methodology.

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