Is vanadium ion permeability independent of membrane thickness?
Bibliographic record
Abstract
Testing the diffusion-driven crossover of vanadium ions in diffusion cells is a standard characterization method for membranes used in vanadium redox flow batteries. For better comparability, the flux is recalculated into a permeability value by normalizing the flux for membrane thickness, area, the cell volume, and the concentration difference between the donating and receiving cells. The assumption is that permeability is an intrinsic material property, independent of membrane thickness. However, this work reveals that this assumption is not correct. By analyzing the vanadium crossover through membranes of different thickness, it is demonstrated that the transport of VO 2+ ions across membranes is controlled by two transport resistances: R IF (a resistance hindering ion transport over the membrane/solution interface into and out of the membrane) and R bulk (the transport resistance through the membrane). Comparable permeability values are only obtained when membrane thicknesses are so large that R bulk >> R IF . Consequently, the permeability data reported in the literature might have low accuracy. R IF emerges as an important new development target, which, if well understood, can lead to breakthroughs in membrane performance.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".