Improving Lithium-Ion Batteries By Replacing Polyethylene Terephthalate Jellyroll Tape
Bibliographic record
Abstract
Every lithium-ion battery cell produced today that is either wound or stacked contains tape. This tape serves the mechanical purpose of holding together the wound jellyroll or stacked electrodes before inserting it into the cell casing, after which the tape serves no purpose. Battery manufacturers often test inactive cell parts for their physical parameters, i.e., elongation, water absorption, and temperature resistance.1 However, their chemical stability is often overlooked. Recently, it was demonstrated that polyethylene terephthalate (PET) tape can partially dissolve in the harsh lithium-ion battery cell chemistry into its monomer dimethyl terephthalate (DMT). This molecule can act as an unwanted redox shuttle in LFP/graphite or NMC811/graphite cells, inducing self-discharge of the battery.2 Figure 1 shows Fourier-transform infrared (FTIR) spectra of tapes obtained from discarded cellphone batteries. Many well-known lithium-ion battery producers use PET tape in their products. In addition, the FTIR spectra show that after the cells have been cycled, the surface layer of these tapes is severely corroded. This study will show open circuit storage, Ultra-High Precision Coulometry, and long-term cycling results from LFP/graphite cells with PET tape. The study will also show how swapping PET tape for a more stable alternative can significantly improve the performance and reduce the self-discharge of LFP/graphite pouch cells. Figure caption: Figure 1 . FTIR spectra of jellyroll closing tapes (a) extracted from discarded cellphone batteries (b). References: E. Foreman et al., Adv. Sustainable Syst., 1, 1700061 (2017). S. Buechele et al., J. Electrochem. Soc., 170, 010511 (2023). 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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.002 |
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".