Macromolecular Design Strategies for Preventing Active-Material Crossover in Non-Aqueous All-Organic Redox-Flow Batteries

Redox flow batteries are a nascent, yet promising, energy storage technology for which widespread deployment is hampered by technical and economic challenges. A performance-determining component in the reactor, present-day electrodes are often borrowed from adjacent electrochemical technologies rather than specifically designed for use in flow batteries. A lack of structural diversity in commercial offerings, coupled with the time constraints of wet-lab experiments, render broad electrode screening infeasible without a modeling complement. Herein, an experimentally validated model of a vanadium redox flow cell is used to generate polarization data for electrodes with different macrohomogeneous properties (thickness, porosity, volumetric surface area, and kinetic rate constant). Using these data sets, we then build and train a neural network with minimal average root-mean squared testing error (17.9 ± 1.8 mA cm<sup>−2</sup>) to compute individual parameter sweeps along the cell polarization curve. Finally, we employ a genetic algorithm with the neural network to ascertain electrode property values for improving cell power density. While the developed framework does not supplant experimentation, it is generalizable to different redox chemistries and may inform future electrode design strategies.

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Charge Transfer Characteristics of Diaza-Anthraquinones in Different Solvents and Their Application As Organic Active Material in Redox Flow Batteries

ECS Meeting Abstracts ◽

10.1149/ma2018-01/39/2292 ◽

2018 ◽

Keyword(s):

Charge Transfer ◽

Active Material ◽

Redox Flow Batteries ◽

Transfer Characteristics ◽

Flow Batteries

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Leveraging Neural Networks and Genetic Algorithms to Refine Electrode Properties in Redox Flow Batteries

10.26434/chemrxiv.13626821 ◽

2021 ◽

Author(s):

Kevin Tenny ◽

Richard Braatz ◽

Yet- Ming Chiang ◽

Fikile Brushett

Keyword(s):

Neural Network ◽

Structural Diversity ◽

Cell Polarization ◽

Data Sets ◽

Design Strategies ◽

Kinetic Rate Constant ◽

Individual Parameter ◽

Redox Flow Batteries ◽

Flow Batteries ◽

Testing Error

Redox flow batteries are a nascent, yet promising, energy storage technology for which widespread deployment is hampered by technical and economic challenges. A performance-determining component in the reactor, present-day electrodes are often borrowed from adjacent electrochemical technologies rather than specifically designed for use in flow batteries. A lack of structural diversity in commercial offerings, coupled with the time constraints of wet-lab experiments, render broad electrode screening infeasible without a modeling complement. Herein, an experimentally validated model of a vanadium redox flow cell is used to generate polarization data for electrodes with different macrohomogeneous properties (thickness, porosity, volumetric surface area, and kinetic rate constant). Using these data sets, we then build and train a neural network with minimal average root-mean squared testing error (17.9 ± 1.8 mA cm<sup>−2</sup>) to compute individual parameter sweeps along the cell polarization curve. Finally, we employ a genetic algorithm with the neural network to ascertain electrode property values for improving cell power density. While the developed framework does not supplant experimentation, it is generalizable to different redox chemistries and may inform future electrode design strategies.

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Blatter Radicals as Bipolar Materials for Symmetric Redox-Flow Batteries

10.26434/chemrxiv-2021-d0szn ◽

2021 ◽

Author(s):

Jelte Steen ◽

Jules Nuismer ◽

Vytautas Eiva ◽

Albert Wiglema ◽

Nicolas Daub ◽

...

Keyword(s):

Active Material ◽

Chemical Degradation ◽

Limiting Factors ◽

Redox Potentials ◽

X Ray Crystallography ◽

Redox Flow Batteries ◽

Redox Active ◽

Flow Batteries ◽

The Stability ◽

Bipolar Electrochemistry

Redox-active organic molecules are promising charge-storage materials for redox-flow batteries (RFBs), but material crossover between posolyte/negolyte and chemical degradation are limiting factors in the performance of all-organic RFBs. We demonstrate that the bipolar electrochemistry of 1,2,4-benzotriazin-4-yl (Blatter) radicals allows construction of batteries with symmetric electrolyte composition. Cyclic voltammetry shows that these radicals retain reversible bipolar electrochemistry also in the presence of water. The redox potentials of derivatives with a C(3)-CF3 substituent are least affected by water and, moreover, these compounds show >90% capacity retention after charge/discharge cycling in a static H-cell for seven days (ca. 100 cycles). Testing these materials in a flow regime at 0.1 M concentration of active material confirmed the high cycling stability under conditions relevant for RFB operation, and demonstrated that polarity inversion in a symmetric flow battery may be used to rebalance the cell. Chemical synthesis provides insight in the nature of the charged species by spectroscopy and (for the oxidized state) X-ray crystallography. The stability of these compounds in all three states of charge highlights the potential for application in symmetric organic redox-flow batteries.

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Sulfonated tryptanthrin anolyte increases performance in pH neutral aqueous redox flow batteries

Communications Chemistry ◽

10.1038/s42004-021-00523-0 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Daniela Pinheiro ◽

Marta Pineiro ◽

J. Sérgio Seixas de Melo

Keyword(s):

Alternative Energy ◽

Active Material ◽

High Energy ◽

Disodium Salt ◽

Water Soluble ◽

Great Promise ◽

Safe Alternative ◽

Redox Flow Batteries ◽

Neutral Ph ◽

Flow Batteries

AbstractAqueous organic redox flow batteries (AORFBs) hold great promise as low-cost, environmentally friendly and safe alternative energy storage media. Here we present aqueous organometallic and all-organic active materials for RFBs with a water-soluble active material, sulfonated tryptanthrin (TRYP-SO3H), working at a neutral pH and showing long-term stability. Electrochemical measurements show that TRYP-SO3H displays reversible peaks at neutral pH values, allowing its use as an anolyte combined with potassium ferrocyanide or 4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt monohydrate as catholytes. Single cell tests show reproducible charge-discharge cycles for both catholytes, with significantly improved results for the aqueous all-organic RFB reaching high cell voltage (0.94 V) and high energy efficiencies, stabilized during at least 50 working cycles.

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