Identification of electrochemical reaction products in lithium–oxygen cells with <sup>7</sup>Li nutation spectroscopy
Bibliographic record
Abstract
In the Li–O 2 battery system, it is has been shown to be challenging to differentiate the discharge products or determine the electrolyte stability with direct 7 Li NMR. Defined 7 Li quadrupole lineshapes are not observed for cycled cathodes. Here, 7 Li nutation NMR is demonstrated to be an effective method for the identification of Li 2 O 2 in cycled cathodes. The 7 Li quadrupole interaction of Li 2 O 2 (35 kHz) and Li 2 CO 3 (120 kHz) are of similar magnitude to typically radiofrequency fields (ranging from 40 to 60 kHz). The 7 Li nutation frequency will therefore be influenced by both interactions. The discharge products of the cycled cathodes were determined by comparing the 7 Li nutation frequencies of the cycled cathodes to the 7 Li nutation frequency of the pristine materials when the applied radiofrequency field was 30 kHz. Li 2 CO 3 was determined to be the main discharge product in the propylene carbonate/dimethyl carbonate and trimethyl phosphate electrolyte systems, since the 7 Li nutation frequencies of the cathodes corresponded to the 7 Li nutation frequency of pristine Li 2 CO 3 . The 7 Li nutation frequency of the tetraethylene glycol dimethyl ether cathode was between the 7 Li nutation frequencies of both pristine Li 2 O 2 and pristine Li 2 CO 3 , indicating that both Li 2 O 2 and Li 2 CO 3 were discharge products influencing the observed nutation frequency. From 7 Li nutation NMR the novel trimethyl phosphate electrolyte was determined to be an unsuitable Li–O 2 electrolyte, as the fast 7 Li nutation frequency indicated that Li 2 O 2 was not a primary discharge species. With 17 O NMR, Li 2 CO 3 was confirmed to be a main discharge product formed with the trimethyl phosphate electrolyte.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".