Quantitative Measurement of Compositional Inhomogeneity in NMC Cathodes by X-ray Diffraction
Bibliographic record
Abstract
A novel XRD analysis technique is described for quantitatively measuring compositional inhomogeneity in Li[NixMnyCoz]O2 (NMC) cathode materials and NMC precursors. Single-phase rock salt precursors with varying degrees of compositional inhomogeneity were prepared by grinding mixtures of Ni, Mn and Co oxides for different times and then heating. These precursors were then heated with lithium to form cathode materials. A modified Williamson-Hall analysis was used to measure the degree of compositional inhomogeneity in the precursors and the final NMC materials. This analysis showed that precursors made with low grinding times had higher compositional inhomogeneity and that this compositional inhomogeneity was amplified in the final NMC, leading to interlayer mixing and poor electrochemical performance. Higher precursor grinding times lead to more compositionally homogeneous NMC, while even higher compositional homogeneity was achieved by NMC made from conventional hydroxide precursors, with correspondingly improved electrochemical performance. The ability described here to measure the degree of compositional homogeneity in NMC precursors and NMC cathode materials by simple XRD measurements presents a powerful tool for the research and development of NMC and other cathode materials.
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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 | 0.001 |
| 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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".