Distinguishing Bulk Redox from Near-Surface Degradation in Lithium Nickel Oxide Cathodes
Bibliographic record
Abstract
Ni-rich layered cathodes deliver high energy densities, but uncertainties remain about their charge compensation mechanisms and the degradation processes that limit their cycle life. Recent studies have identified trapped molecular O2 within LiNiO2 at high states of charge, as seen for Li-rich cathodes where excess capacity is associated with reversible O2−/O2 redox. Here we show that bulk redox in LiNiO2 occurs by Ni-O rehybridization, lowering the electron density on O sites, but without significant involvement of molecular O2. Trapped O2 is predominantly associated with surface degradation through contact with the electrolyte, and is accompanied by Ni reduction. O2 is removed on discharge, but an excess of Ni2+ remains forming a reduced surface layer that impedes Li transport. Our findings highlight the importance of separating bulk redox from near-surface degradation, and implicate the instability of delithiated LiNiO2 in contact with the electrolyte in surface degradation through O2 formation.
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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 | 0.000 | 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 | 0.000 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.003 |
| 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".