Critical role of structural order in bipolar redox-active molecules for organic redox flow batteries

Li, Min; Agarwal, Garvit; Shkrob, Ilya A.; VanderLinden, Ryan T.; Case, Julia; Prater, Matthew B.; Rhodes, Zayn; Assary, Rajeev S.

doi:10.1039/d1ta04821j

Cited by 15 publications

(5 citation statements)

References 53 publications

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“…The simple hybrid design with moderate polarity was soluble up to 0.3 M in 1,3-dioxolane with 1.0 M TBABF 4 and showed good chemical stability over 50 cycles with current densities ranging from 20 to 60 µA cm −2 (1.0 to 3.0 C). However, although small molecules and short linkers could instinctively reduce the need for solubilizing molecular parts that do not partake in the charging or discharging process, Li et al showed important irregularities in chemical behavior between phenothiazine and phthalimide moieties tethered through various chain length linkers [161]. Molecular conformations arising from specific chain lengths and flexibilities are found to have a profound effect on the ability to undergo charge transfer and the molecular packing.…”

Section: Bipolar Electrolytesmentioning

confidence: 99%

Building Bridges: Unifying Design and Development Aspects for Advancing Non-Aqueous Redox-Flow Batteries

et al. 2022

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Renewable energy sources have been a topic of ever-increasing interest, not least due to escalating environmental changes. The significant rise of research into energy harvesting and storage over the years has yielded a plethora of approaches and methodologies, and associated reviews of individual aspects thereof. Here, we aim at highlighting a rather new avenue within the field of batteries, the (noaqueous) all-organic redox-flow battery, albeit seeking to provide a comprehensive and wide-ranging overview of the subject matter that covers all associated aspects. This way, subject matter on a historical perspective, general types of redox-flow cells, electrolyte design and function, flow kinetics, and cell design are housed within one work, providing perspective on the all-organic redox-flow battery in a broader sense.

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Section: Bipolar Electrolytesmentioning

confidence: 99%

Building Bridges: Unifying Design and Development Aspects for Advancing Non-Aqueous Redox-Flow Batteries

et al. 2022

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“…A specific approach involves connection of two independent electronically decoupled redox-active cores with an inert linker. Even though such a strategy can provide modularity in bipolar electrolyte design, it can significantly inflate the molecular weight, in addition to introducing nontrivial and potentially detrimental effects of the linker structure on stability . A more challenging approach that could address these limitations involves introducing two electrophores into a single π-system. ,,− Although conjugation of two redox orthogonal functionalities increases peak-to-peak separation between redox events, it leads to destabilization of both charged states.…”

Section: Introductionmentioning

confidence: 99%

Development of Modular Nitrenium Bipolar Electrolytes for Possible Applications in Symmetric Redox Flow Batteries

Varenikov,

Gandelman,

Sigman

2024

J. Am. Chem. Soc.

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Amid the escalating integration of renewable energy sources, the demand for grid energy storage solutions, including non-aqueous organic redox flow batteries (oRFBs), has become ever more pronounced. oRFBs face a primary challenge of irreversible capacity loss attributed to the crossover of redox-active materials between half-cells. A possible solution for the crossover challenge involves utilization of bipolar electrolytes that act as both the catholyte and anolyte. Identifying such molecules poses several challenges as it requires a delicate balance between the stability of both oxidation states and energy density, which is influenced by the separation between the two redox events. We report the development of a diaminotriazolium redox-active core capable of producing two electronically distinct persistent radical species with typically extreme reduction potentials (E 1/2 red < −2 V, E 1/2 ox > +1 V, vs Fc 0/+ ) and up to 3.55 V separation between the two redox events. Structure−property optimization studies allowed us to identify factors responsible for fine-tuning of potentials for both redox events, as well as separation between them. Mechanistic studies revealed two primary decomposition pathways for the neutral radical charged species and one for the radical biscation. Additionally, statistical modeling provided evidence for the molecular descriptors to allow identification of the structural features responsible for stability of radical species and to propose more stable analogues.

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“…Similar symmetric cell architectures have been explored in the development of bipolar organic molecules, though they have yet to be commercialized. [29][30][31][32][33][34] To address the inherent tradeoff relationship between the solute concentration and the performance of RFBs, we are interested in designing a rechargeable half-cell reaction where the charged and discharged species are both gaseous. With this approach, the redox-active gas, in principle, no longer needs to remain dissolved in the electrolyte all the time and can be stored in a gas tank and supplied on demand (Figure 1B).…”

Section: Introductionmentioning

confidence: 99%

Gaseous Nitrogen Oxides Catholyte for Rechargeable Redox Flow Batteries

2023

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There is a strong interest in finding highly soluble redox compounds to improve the energy density of redox flow batteries (RFBs). However, the performance of electrolytes is often negatively influenced by high solute concentration. Herein, we designed a highpotential (0.5 V vs. Ag/Ag + ) catholyte for RFBs, where the charged and discharged species are both gaseous nitrogen oxides (NO x ). These species can be liberated from the liquid electrolyte and stored in a separate gas container, allowing scale-up of storage capacity without increasing the concentration and volume of the electrolyte. The oxidation of NO in the presence of NO 3 À affords N 2 O 3 , and the reduction of N 2 O 3 regenerates NO and NO 3 À , together affording the electrochemical reaction: NO 3 À + 3 NO* * 2 N 2 O 3 + e À with a low mass/charge ratio of 152 grams per mole of stored electron. A proofof-concept NO x symmetric H-cell shows 200 stable cycles over 400 hours with > 97 % Coulombic efficiency and negligible capacity decay.

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Critical role of structural order in bipolar redox-active molecules for organic redox flow batteries

Abstract: Bipolar redox-active molecules (BRMs) have been suggested as a means to address crossover related issues in all-organic redox flow batteries (RFBs). In such species, electron donors (anolytes) and electron acceptors...

Cited by 15 publications

References 53 publications

Building Bridges: Unifying Design and Development Aspects for Advancing Non-Aqueous Redox-Flow Batteries

Building Bridges: Unifying Design and Development Aspects for Advancing Non-Aqueous Redox-Flow Batteries

Development of Modular Nitrenium Bipolar Electrolytes for Possible Applications in Symmetric Redox Flow Batteries

Gaseous Nitrogen Oxides Catholyte for Rechargeable Redox Flow Batteries

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