Phase-Transition Mechanism Investigations in Monoclinic Li<sub>2</sub>FeSiO<sub>4</sub> Orthosilicate Cathode
Bibliographic record
Abstract
Lithium transition metal silicates Li2 M SiO4 ( M = Fe, Mn, Co, etc.)1 , 2, well-known for their 2-Li theoretical capacity, draw increasingly more attention. In this text, we propose a hydrothermal method3 to obtain phase-pure nanoscale lithium iron silicate Li2FeSiO4 for probing its electrochemical performance as Li-ion battery cathode. Two types of Li2FeSiO4 crystals are prepared, namely low-temperature monoclinic phase and high-temperature orthorhombic phase and their electrochemical performance is found to be strongly structure-depended. As a result, the electrochemistry-structure relationships are systematically investigated using in-situ synchrotron XRD/XANES characterizations and first-principles calculations. The results demonstrate that there are obvious phase transitions for the metastable monoclinic Li2FeSiO4 electrode upon cycling4 and the Li ion has poor diffusion kinetics with activation energy of minimum 0.80 eV in both structures. Furthermore the charge compensation mechanism is discussed by XANES and calculations in monoclinic Li2FeSiO4 structure for more than one Li extraction. All of these findings reveal some missing links in our fundamental comprehension of these materials and provide ideas for designing/obtaining improved silicate cathode materials. References 1. Nyten, A., Abouimrane, A., Armand, M., Gustafsson, T. & Thomas, J. O. Electrochemical performance of Li2FeSiO4 as a new Li-battery cathode material. Electrochem. Commun. 7, 156-160, (2005). 2. Gummow, R. J., He, Y., Recent progress in the development of Li2MnSiO4 cathode materials. J. Power Sources, 253 , 253, 315-331 (2014). 3. Wei, H.J. et al. Synthesis and Characterization of Li2FeSiO4 as Candidate High-Capacity Li-ion Battery Cathode Material. 227th ECS Meeting, May 24-28 (2015), Chicago, Illinois, USA. 4. Xia Lu, Huijing Wei, Hsien-Chieh Chiu, Raynald Gauvin, Pierre Hovington, Abdelbast Guerfi, Karim Zaghib and George P. Demopoulos, Rate-dependent phase transitions in Li2FeSiO4 cathode nanocrystals, Sci. Re. in revision (2014).
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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) | 0.000 | 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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".