Evaluation of Litdi Vs. LiPF<sub>6</sub> As Electrolytes in Contact with Several Cathodes and Anodes Materials
Notice bibliographique
Résumé
Introduction Lithium-ion batteries supplying energy for electric cars and other devices are mostly based on electrolytes using LiPF 6 . The popularity of this salt is mostly due to the formation of a passivation layer with aluminum which made possible the utilization of this low cost material as current collector. In counter part, the thermal instability of LiPF 6 and it’s reactivity with moisture or protic species release a toxic, highly aggressive and undesirable gaz, HF. These major drawbacks have prompt researchers to replace LiPF 6 by salts with improved thermal, chemical and electrochemical properties. Unfortunately, most attempts to replace LiPF 6 with hydrolytically-stable salts have been unsuccessful because of Al corrosion [1] . Niedzicki et al. [2] showed that lithium 4,5-dicyano-2-(trifluoromethyl) imidazolide, commonly known as LiTDI could be an interesting substitute to LiPF 6 . They showed LiTDI didn’t corrode Al, which are consistent with our results, and have a thermal stability up to 250°C. It has a satisfactory conductivity thereby showing good performances with LiMn 2 O 4 at operational voltage range of 3 - 4.3 V. In the present study, we are interested to compare LiPF 6 and LiTDI. This research is in collaboration between Arkema [3] , which has developed an industrial process to synthesize battery grade LiTDI, and Hydro-Québec. Electrochemical performances of LiTDI in EC-DEC (3-7 v-v) was evaluated in coin cells (vs. Li) with four different cathodes materials: LiNi 1/3 Mn 1/3 Co 1/3 O 2 [3-4.2V], LiMn 2 O 4 [3–4.4V], LiFePO 4 [2-4V], LiCoO 2 [3- 4.2V] and also with two type of anodes materials: graphite [0-2.5V], and Li 4 Ti 5 O 12 [1.2-2.5V]. Results The results obtained in this study with LiTDI are very promising. For all materials tested, the LiTDI has showed good compatibilities and results are comparable with those of LiPF 6 . During the formation, we found that: - for positive electrodes, results with and without FEC gave similar discharged and irreversible capacities compared to LiPF 6 . - for graphite, results showed that it’s necessary to use FEC to form a thin and stable SEI (validated by SEM analysis). - for Li 4 Ti 5 O 12 , the use of additive increases the irreversible capacity. For all materials, the ragone analysis showed competitive results between LiTDI and LiPF 6 , as it can be seen in the Figure 1, for LiNi 1/3 Mn 1/3 Co 1/3 O 2 and LiMn 2 O 4 . Moreover, thanks to its high chemical stability, LiTDI has showed better performances than LiPF 6 in term of safety. Indeed, burning experiments have been realized and clearly showed a decrease of generated dangerous gas. Pouch cells batteries with LiNi 1/3 Mn 1/3 Co 1/3 O 2 /Li 4 Ti 5 O 12 [1.5-2.8V] were also assembled for long-term cycling (C/4-D/4) at 25°C and 40°C. At the moment at 130 cycles, the lost capacity is only 2% for each temperature, which demonstrate the good stability of LiTDI. References 1. K. Krause et al , J. Power Sources, 68 ( 1997 ), 320-325 2. Niedzicki et al. , J . Power Sources , 196 ( 2011 ), 8696-8700 3. G. Schmidt et al ., FR2982610.
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Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,002 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
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