Safety Testing with Nonwoven Nanofiber Separators: Comparing Shutdown Separators to Thermally Stable Separators
Bibliographic record
Abstract
Pouch cells of LiFePo4 and graphite at 2700 mAh capacity were made from commercial electrodes with four different separators: 25 micron polypropylene (PP), 25 micron ceramic coated polyethylene (PE/C), 25 micron nanofiber nonwoven (Dreamweaver Silver – DWI/S), and 25 micron nanofiber nonwoven containing para-aramid fibers (Dreamweaver Gold – DWI/G). The cells had nearly identical electrical performance. The cells underwent hard short, overcharge, hot box and nail penetration tests. All cells passed hard short and overcharge tests. In hot box tests, the PE/C and PP cells experienced internal shorts when the cell temperature reached 145 C. The DWI/S and DWI/G cells showed a steady voltage for 1 hour, and continued to function after the test was completed. In the nail penetration test, the PP and PE/C cells experienced an immediate drop to zero voltage, and the temperature rose quickly to 115 C (PE/C) and 85 C (PP). The DWI/S and DWI/G cells rose to 60 C and 40C respectively, but exhibited only a ~100 mV drop in voltage and continued to function with the nail in the cell. Autopsies of the cells revealed significant shrinkage and cracking of the polyolefin separators, but primarily mechanical damage to the DWI separators.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".