Determining the Transport Properties of Electrolyte Solutions By in-Situ NMR Imaging and Inverse Modeling
Bibliographic record
Abstract
We used NMR imaging (MRI) combined with a data analysis by modeling of the inverse mass transport problem, to determine salt diffusion coefficients D+ and transference numbers t+ in electrolyte solutions of interest for Li-ion batteries. Sensitivity analyses have shown that accurate estimates of these parameters (as a function of concentration) are critical to the reliability of the predictions provided by models of porous electrodes. The inverse modeling (IM) solution was generated with an extension of the Planck-Nernst model for the transport of ionic species in electrolyte solutions. Concentration dependent diffusion coefficients and transference numbers were derived using concentration profiles obtained from in-situ 19F MRI measurements. Material properties were reconstructed with minimal assumptions, using methods of variational optimization to minimize the least-square deviation between experimental and simulated concentration values. Diffusion coefficients obtained by pulsed field gradient NMR (PFG NMR) fall within the 95% confidence bounds for the diffusion coefficient values obtained by the MRI+IM method. This demonstrates that PFG NMR determines chemical (Fickian) diffusion coefficients in concentrated electrolyte solutions and not self-diffusion coefficients. The MRI+IM method also yields the concentration dependence of the Li+transference number in agreement with trends obtained by electrochemical methods for similar systems and with predictions of theoretical models for concentrated electrolyte solutions, in marked contrast to the salt concentration dependence of transport numbers determined from PFG NMR data. Acknowledgements The authors acknowledge funding through the NSERC APC program and GM of Canada. Figure 1
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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 | 0.001 |
| 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 | 0.000 | 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".