Synchrotron X-Ray radiography of vanadium redox flow batteries – Time and spatial resolved electrolyte flow in porous carbon electrodes
Bibliographic record
Abstract
A porous carbon electrode fully saturated with electrolyte is one crucial aspect of vanadium redox flow battery efficiency. It determines the electrochemically active surface area, provides more active sites for the reaction during operation, and prevents local degradation due to inhomogeneities in electrolyte distribution. We investigate the electrolyte invasion and distribution at open-circuit potential in heat-treated carbon felt electrodes at varying compression ratios and flow field configurations, using synchrotron X-ray radiography. The quantitative analysis yields time-resolved saturation values of the injection and resolves local changes in saturation to detect areas of lower electrolyte accessibility. Compression ratios of 50% and above lead to a high electrode utilization with more than 97% saturation over the felt thickness. In contrast, carbon felts at 25% and 17% compression only reach 49% and 15% saturation near the flow fields. However, increasing the flow velocity after the injection causes the boundary area next to the flow field to fill even at low compressions. This area is especially critical for the electrode utilization since it is invaded after the bulk. Depending on the compression level, it does not reach full saturation.
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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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".