Bipolar Redox‐Active Molecules in Non‐Aqueous Organic Redox Flow Batteries: Status and Challenges

Li, Min; Case, Julia

doi:10.1002/celc.202001584

Cited by 48 publications

(65 citation statements)

References 81 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The need to evolve RFBs tends towards the use of organic Bipolar Redox-Active Molecules to promote a more robust and reliable design. 49 This is an elegant solution to the challenge of cross contamination and membrane costs. In the case of NARFB, the choice of solvent will allow a very large potential window and increase the accessible energy density.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, research to provide high energy density ORFB systems has already started to move towards nonaqueous (NA) systems based on organic solvents, with wider electrochemical stability window to develop the so called NAORFBs. [40][41][42][43][44][45][46][47][48][49] We have recently demonstrated that 1,3dipropylodimethoxyquinolinoacridinium tetrafluoroborate salt helicene (denoted H C + , see Scheme 1) 41 possess remarkable performance as an electrolyte material in symmetrical ORFBs via its three stable H C •++ / H C + / H C • redox states. The H C + ions showed impressive redox stability, and a high OCV of 2.12 V in a static RFB model.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Increased performance of an all-organic redox flow battery model via nitration of the [4]helicenium DMQA ion electrolyte

et al. 2022

View full text Add to dashboard Cite

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Increased performance of an all-organic redox flow battery model via nitration of the [4]helicenium DMQA ion electrolyte

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Interestingly, this strategy mirrors the use of bipolar redox-active molecules (BRMs), an emerging strategy in the development of nonaqueous RFBs such as 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). 71 The algorithm thus rediscovers a fundamental concept in radical chemistry that has shown promise in the development of symmetric RFBs. However, unlike existing BRMs with relatively bulky functional groups, those discovered by RL more efficiently blend all required functionality into a much lower molecular weight moiety.…”

Section: Error Analysis Of the Surrogate Objective Functionmentioning

confidence: 99%

Multi-objective goal-directed optimization of de novo stable organic radicals for aqueous redox flow batteries

Law

Tripp

et al. 2021

Preprint

View full text Add to dashboard Cite

Advances in the field of goal-directed molecular optimization offer the promise to find feasible candidates for even the most challenging molecular design applications. However, several obstacles remain in applying these tools to practical problems, including lengthy computational or experimental evaluation, synthesizability considerations, and a vast potential search space. As an example of a fundamental design challenge with industrial relevance, we search for novel stable radical scaffolds for an aqueous redox flow battery that simultaneously satisfy redox requirements at the anode and cathode. To meet this challenge, we develop a new open-source molecular optimization framework based on AlphaZero coupled with a fast, machine learning-derived surrogate objective trained with nearly 100,000 quantum chemistry simulations. The objective function comprises two graph neural networks: one that predicts adiabatic oxidation and reduction potentials and a second that predicts electron density and local 3D environment, previously shown to be correlated with radical persistence and stability. With no hand-coded knowledge of organic chemistry, the reinforcement learning agent finds molecule candidates that satisfy a precise combination of redox, stability, and synthesizability requirements defined at the quantum chemistry level, many of which have reasonable predicted retrosynthetic pathways. The optimized molecules show that alternative stable radical scaffolds may offer a unique profile of stability and redox potentials to enable low-cost symmetric aqueous redox flow batteries.

show abstract

“…7 For these reasons, redox flow batteries using nonaqueous solvents and redox-active organic molecules are being explored. 14,15,16,17 Non-aqueous redox flow batteries (NRFBs) have a wider window of electrochemical stability (up to 5 V in acetonitrile), enabling access to larger battery voltages. In addition, redox-active organic molecules can be synthetically tuned to achieve high energy densities, solubilities, and stabilities.…”

Section: Introductionmentioning

confidence: 99%

“…To date, many organic molecules have been evaluated as anolytes (negative charge carriers) and catholytes (positive charge carriers) in NRFBs. 14,15,16,17 Among the anolytes, Nheterocyclic aromatic compounds have been prominent due to their reversible reductions, including viologens, 18,19,20,21,22,23 Nsubstituted phthalimides, 24,25,26,27,28,29,30 2,1,3benzothiadiazoles, 31,32,33,34 pyridiniums, 35,36,37,38,39,40 and bipyrimidines. 41 Despite these successes, the structural variety within these anolytes is limited due to the stringent requirements posed by the application (i.e., combining low redox potentials and high solubility while being exceptionally stable in all states of charge).…”

Section: Introductionmentioning

confidence: 99%

Balancing high energy density and chemical stability in redox flow batteries with symmetric tetrazines

Garza

Kaur

Shkrob

et al. 2021

Preprint

View full text Add to dashboard Cite

Nonaqueous redox flow batteries are a promising technology for grid-scale energy storage, however, their commercial success relies on identifying redox active materials that exhibit extreme potentials, high solubilities in all states of charge, and long cycling stabilities. Meeting these requirements has been particularly challenging for molecules capable of storing negative charge. Within this context, the symmetric tetrazines remain unexplored despite their unique structural properties that enable them to meet these challenges. Herein, we prepared s-tetrazines substituted with methyl, methoxy, and thiomethyl substituents and evaluated their electrochemical properties, solubility, and cycling stability. These studies revealed that 3,6-dimethoxy-s-tetrazine undergoes a reversible one-electron reduction to generate a soluble (>0.5 M in electrolyte/solvent) and stable (t1/2 > 1240 h) radical anion. When implemented in a lab-scale flow battery, it exhibited a relatively slow capacity fade of 13% over 100 cycles (38 h). Given their uncommonly high solubility and cycling stability, we believe that s-tetrazine derivatives should be further explored for non-aqueous redox flow batteries.

show abstract

Bipolar Redox‐Active Molecules in Non‐Aqueous Organic Redox Flow Batteries: Status and Challenges

Abstract: in 2011. She has been a member of the Joint Center for Energy Storage Research since 2015 with her research group working on redoxmer design and characterization. Scheme 1. Schematic illustration of a redox-flow battery.

Cited by 48 publications

References 81 publications

Increased performance of an all-organic redox flow battery model via nitration of the [4]helicenium DMQA ion electrolyte

Increased performance of an all-organic redox flow battery model via nitration of the [4]helicenium DMQA ion electrolyte

Multi-objective goal-directed optimization of de novo stable organic radicals for aqueous redox flow batteries

Balancing high energy density and chemical stability in redox flow batteries with symmetric tetrazines

Contact Info

Product

Resources

About