NaV<sub>1.25</sub>Ti<sub>0.75</sub>O<sub>4</sub>: A Potential Post-Spinel Cathode Material for Mg Batteries
Bibliographic record
Abstract
Rechargeable Mg batteries are promising candidates for high energy density storage in theory, when a Mg metal anode is combined with an oxide cathode material. Despite the widely observed sluggish Mg 2+ diffusion in most oxide lattices, recent first-principles calculations predicted low diffusion barriers in the calcium ferrite (CF)-type post-spinel structures. In the present work, we experimentally examine the prospect of CF-type NaV 1.25 Ti 0.75 O 4 as a Mg cathode. The Na + ions, which lie in the ion migration pathway, need to be removed or exchanged with Mg 2+ to allow Mg 2+ de/intercalation. Partial desodiation was achieved through chemical and electrochemical methods, as proven by X-ray diffraction and X-ray absorption spectroscopy, but deep desodiation was accompanied by partial amorphization of the material. Mg 2+ ion exchange at moderate temperature (80 °C) resulted in the formation of Na 0.19 Mg 0.41 V 1.25 Ti 0.75 O 4; however, phase transformation was observed when higher temperatures were applied to attempt complete ion exchange. Such phenomena point to the instability of the CF lattice when the tunnel is empty or occupied by a small ion (Mg 2+ ). Thus, while the low migration barrier predicted by computation is partly based on the relative metastability of the theoretical CF-Mg x V 1.25 Ti 0.75 O 4 lattice, the difficulty in stabilizing it also renders the material synthetically nonaccessible, hindering this post-spinel’s application as an electrode material.
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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".