Evaluation of Two-Electron Bispyridinylidene Anolytes and a TEMPO Catholyte for Non-Aqueous Redox Flow Batteries
Bibliographic record
Abstract
All-organic, non-aqueous cells employing a 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) catholyte and two separate bispyridinylidene derivatives, one featuring a N,N′-propylene bridge and the other N,N′-di- n -propyl substituted, as anolyte-active materials have been investigated under static conditions in 0.8 M sodium tetrafluoroborate (NaBF 4 )/dimethylformamide (DMF) supporting electrolyte and an anion exchange membrane. Longer cycle life was achieved using the bridged bispyridinylidene (52 h/39 cycles to 50% theoretical discharge capacity, with E cell of 1.88 V) vs unbridged derivative (7 h/5 cycles to 50% theoretical discharge capacity, with E cell of 1.93 V). Based on stability tests conducted by NMR spectroscopy, both redox states (0/2+) for the two bispyridinylidene anolytes showed relatively high stability in the electrolyte, individually, which contrasts the poor cycling performance of their cells. A number of factors were identified that contributed to this including cross contamination through the membrane, the instability of TEMPO cation in the electrolyte, and the observation that the unbridged bispyridinylidene reacts with the corresponding bipyridinium redox partner over time in DMF. This work indicates the importance of having an alkyl bridge between pyridyl rings to support bispyridinylidene stability over cycling, and the need for more stable catholyte alternatives to TEMPO in DMF.
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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 | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".