Highly soluble viologen-PEG conjugates for aqueous organic redox flow batteries
Bibliographic record
Abstract
Aqueous organic redox flow batteries (AORFBs) are a promising solution for the large-scale storage of renewable energy. These systems store electricity via electrochemically active organic molecules in an aqueous solvent, which offers superior safety and renewability compared to organic solvents. Furthermore, AORFBs provide a cost-effective alternative to aqueous vanadium-based redox flow batteries. However, designing molecules with adequate electrochemical properties that are also soluble in water and stable during long-term cycling remains a challenge. In this study, we investigate the impact of PEGylation as a potential solution to address these issues. A simple and efficient synthetic approach was used to prepare PEG-containing viologens, with different chain lengths, counterions and symmetries. Their physical and electrochemical properties, including solubility, viscosity, redox potential and heterogeneous electron transfer rate constant, were studied. The results demonstrate that PEG chains enhance solubility in water, and that the chloride counterion increases solubility by 25% compared to the tosylate counterion. None of the studied modifications had a significant impact on the electrochemical properties, demonstrating the usefulness of N-substitution in tuning the solubility without compromising the use of the viologens as negolytes. Although asymmetric derivatives yielded higher solubilities (up to 2.7 M), the most stable organic negolyte under cycling conditions at high concentration (1 M) was a symmetric viologen containing two PEG units (12 days with 0.29% of capacity loss per day). Therefore, the PEGylation of organic molecules represents a valuable approach to improving the aqueous solubility of electrolytes for use in aqueous organic redox flow batteries.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".