Safety Testing in Lithium Ion Cells Comparing Thermally Stable Nanofiber-Based Separators to Traditional Polyolefin Separators
Bibliographic record
Abstract
2.7 Ah Pouch cells of LiFePo4 and graphite were made with four different separators: 25 micron polypropylene dry process (PP) 25 micron ceramic coated polyethylene wet process (PE) Dreamweaver Silver 25 micron Dreamweaver Gold 25 micron. Starting electrical performance was nearly identical between the cells before testing: Hard Short: The cells were shorted between their tabs. The cells all performed the same, with the anode tab (4 mm tab) getting red hot, and the cells slowly heating and internally gassing until the seal broke. Overcharge: The cells were charged at 2C from 30% SOC. All uncoated cells failed at 5.55 V by outgassing, while the ceramic coated PE failed at 5.9 V. There were no flames, and the temperature rise was uniform between cells. Hot Box: Cells made with PP and PE/ceramic separators both had fast temperature rise and they also both experienced a catastrophic short after around 20 minutes. DWI Silver and Gold cells maintained operational voltage for 1 hour and survived without shorting. The short for the PE/ceramic cell occurred with onset at around 140 C, and for the PP cell at around 145 C. Both of the DWI cells rose to 170C, the oven temperature, without experiencing a short. Nail Penetration: Cells made with both PP and PE separators dropped immediately to a persistent 0V along with faster and higher temperature rise (up to 115 C) than the cells made with Gold (40 C) and Silver (60 C). The Dreamweaver cells, on the contrary, experienced only a small voltage drop of approximately 100 mV, with a slow rise thereafter as the cell discharged. The DWI cells continued to function throughout the test and retained 2/3 of their charge and capacity after completion of the test. Shutdown Function: In no test was a shutdown function observed to improve the performance in any of the cells. 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 | 0.001 | 0.000 |
| 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".