Concentration Dependent Solution Structure and Transport Mechanism in High Voltage LiTFSI–Adiponitrile Electrolytes
Bibliographic record
Abstract
The physiochemical properties of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in adiponitrile (ADN) electrolytes were explored as a function of concentration. The phase diagram and ionic conductivity plots show a distinct relationship between the eutectic composition of the electrolyte and the concentration of maximum ionic conductivity in the 25 °C isotherm. We propose a structure-based explanation for the variation of electrolyte ionic conductivity with LiTFSI concentration, where the eutectic concentration is a transitionary region at which the structure changes from solvated contact ion pairs to extended units of [Li z (ADN) x TFSI y ] z−y aggregates. It is found through diffusion coefficient measurements using pulsed-field gradient (PFG) NMR that both <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>D</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>L</mml:mi> <mml:mi>i</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> <mml:mo stretchy="true">/</mml:mo> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>D</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>T</mml:mi> <mml:mi>F</mml:mi> <mml:mi>S</mml:mi> <mml:mi>I</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>D</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>L</mml:mi> <mml:mi>i</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> <mml:mo stretchy="true">/</mml:mo> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>D</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>A</mml:mi> <mml:mi>D</mml:mi> <mml:mi>N</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> increase with concentration until 2.9 M, where after Li + becomes the fastest diffusing species, suggesting that ion hopping becomes the dominant transport mechanism for Li + . Variable diffusion-time (Δ) PFG NMR is used to track this evolution of the ion transport mechanism. A differentiation in Li + transport between the micro and bulk levels that increases with concentration was observed. It is proposed that ion hopping within [Li z (ADN) x TFSI y ] z−y aggregates dominates the micro-scale, while the bulk-scale is governed by vehicular transport. Lastly, we demonstrate that LiTFSI in ADN is a suitable electrolyte system for use in Li-O 2 cells.
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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".