A Novel Quantification Method for High Voltage Structural Evolution in Sodium and Lithium Layered Oxides
Bibliographic record
Abstract
Abstract High‐voltage cycling of layered alkali transition metal oxides in Li‐ and Na‐ion cells increases energy density but greatly diminishes their lifetime. One of the most common Na‐ion cathode materials, O3‐type Na[Ni 1/3 Fe 1/3 Mn 1/3 ]O 2 (NFM111), exhibits a well understood reversible octahedral to prismatic (O3↔P3) phase transition below 4.0 V, but its structural changes at higher voltage remain unclear. In this study, the structural evolution of NFM111 upon high voltage cycling is investigated by in‐situ X‐ray diffraction (XRD). It is found that the P3 phase that persists upon charging to 4 V transforms into a new octahedral/prismatic (OP) hybrid structure after just one charge to 4.3 V, with no recovery of the P3 phase in further cycles. A novel XRD‐analysis method, centered on the stacking factor “ z ”, is developed to quantify the stacking fractions in the OP hybrid structure and track their evolution during cycling, revealing structural hysteresis in the OP phase. This method is extended to the O3/O1 stacking, providing deeper understanding of high‐voltage phase transitions in Li x NiO 2 and Li x CoO 2 (x < 0.25) by revisiting previously reported in‐situ XRD data. Together, it is demonstrated that the “z‐factor” method is widely applicable to probing the high‐voltage phase transitions in both Li and Na layered oxides.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".