Decoupling Electrochemical Kinetics of Li-Rich and Li-Poor Phases in LiFePO<sub>4</sub> Cathodes Using Single-Particle Electrochemical Impedance Spectroscopy
Bibliographic record
Abstract
LiFePO 4 (LFP) undergoes a two-phase transformation during lithium insertion or extraction, forming lithium-rich and lithium-poor phases. Determining the kinetic parameters of these phases is crucial for electrochemical models but remains challenging. In this study, we decouple the reaction and diffusion kinetics of the Li-rich and Li-poor phases in LFP cathodes using single-particle electrochemical impedance spectroscopy (EIS). LFP agglomerates comprising primary particles are fabricated into single-particle microelectrodes. EIS measurements are conducted on single LFP particles at various insertion ratios. A physics-based impedance model is developed for phase-transformation electrodes, and the evolution of the exchange current density ( i 0 ) and diffusion coefficient ( D Li ) for both phases is extracted. In the single-phase region, the Li-poor phase exhibits a steeper change in i 0 with varying insertion ratios compared with the Li-rich phase. In the two-phase coexistence region, the Li-poor phase shows a higher i 0 than the Li-rich phase. Additionally, D Li for the Li-poor phase is higher than that for the Li-rich phase in both the single-phase and two-phase coexistence regions. We also compare the kinetic parameters of the Li-rich and Li-poor phases in LFP agglomerates of varying particle sizes to clarify the impact of particle size on electrochemical kinetics. The proposed impedance-based approach decouples the electrochemical kinetics of Li-rich and Li-poor phases in LFP cathodes, and the extracted kinetic parameters serve as the basis for developing models considering phase transformation.
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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 | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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 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".