Double Concerted Two-Electron Bispyridinylidenes for Symmetric Non-Aqueous Organic Redox Flow Batteries
Bibliographic record
Abstract
Large-scale energy storage is essential in shifting from fossil fuel-based energy sources to renewables, particularly for the integration of intermittent renewable sources like wind and solar with the electrical grid. Redox flow batteries (RFBs) are a leading technology for this purpose. Most RFBs use metal-based species, with vanadium RFBs being the most developed, but organic active materials theoretically offer the possibility to store more energy per volume with lower cost and environmental impact. To date however, the development of all-organic RFBs is hindered by material crossover, limited energy density, and poor stability of active materials. Like for vanadium RFBs, major issues around crossover can be minimized through a symmetric organic RFB design, where a single bipolar organic molecule is used as the active species for both negalyte and posilyte.[1] In this presentation, our recent work on the development of bispyridinylidenes as intrinsic bipolar molecules for symmetric non-aqueous RFBs will be discussed.[2] These compounds are unique in that they exhibit basically concerted double two-electron redox activity. The effects of derivatization of the bispyridinylidenes core on solubility and stability of the various oxidation states (+2, 0, -2), as well as the cell potential, will be discussed. The performance in small scale flow cells will also be discussed. Considering previous evidence for active material solubility limits of ∼2 M, and the benefits of a symmetric design, such double concerted two-electron bipolar active materials will likely be key to developing energy dense non-aqueous organic RFBs. References: [1]. Raihan, M. A.; Dyker, C. A. Status and Prospects for Symmetric Organic Redox Flow Batteries. J. Energy Chem. 2025, 100, 125-143. [2]. Raihan, M. A.; Dyker, C. A. Ester-Substituted Bispyridinylidenes: Double Concerted Two-Electron Bipolar Molecules for Symmetric Organic Redox Flow Batteries. ACS Energy Lett. 2023, 8, 3314–3322.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".