Hydrogen Depolarised Anode: Proof of Concept and Operational Overpotential Determination
Notice bibliographique
Résumé
Lithium hydroxide world demand is growing very fast and will drastically increase in the next years. It could become a critical material in the coming years. This lightning growth is mostly due to lithium-ion batteries development. In particular, the proportion always more important of hybrid and electric cars sell worldwide. This consumer change is mainly driven by a better environmental concern. However, the battery production price and its high environmental cost are breaking the market potential. In order to jointly decreasing these two limitations, Nemaska Lithium is developing a non conventional approach to produce battery-grade lithium hydroxide from his spodumene mine located in the north of Quebec. Its electro-membrane process mainly consumes green electricity and avoid the utilization of huge quantity of chemical products. In a constant improvement ambition, Nemaska Lithium decided to study the opportunity to use a Hydrogen Depolarized Anode (HDA) in order to save energy for the direct electro-membrane synthesis of high purity Lithium Hydroxide. This new approach is inspired from proton exchange membrane fuel cells because the anode reaction is similar (H2 → 2H+ + 2e-). This similarity has oriented the general architecture of the electrode. Thus, it was chosen to supply with hydrogen the back of the HDA and to privilege a porous structure. The other side of the HDA is in close contact with the electrolyte composed of lithium sulfate and sulfuric acid (to enhance the conductivity). The cell porosity orients the reactant to the platinum catalytic sites where the reaction itself is taking place. From this place, produced protons must travel through the Nafion and the electrolyte while electrons circulate on the opposite way across the cell porosity. As if global operation is similar between fuel cells and HDA, a certain number of specificities that do not exist in fuel cell can influence the performance of the HDA. To name just a few main examples, the influence of a liquid phase in contact with the anode and the impact of the lithium sulfate on the kinetic reaction. To reach a most complete possible comprehension of this new technology, a R&D equipment has been specifically developed to support the operation of a 50 cm2 cell. This study will demonstrate the ability of an HDA to oxidize efficiently hydrogen without needing an important overpotential. Two approaches will be developed to isolate the anode overpotential induced during its operation. Following that, the influence of different parameters like salt concentration and Nafion humidity will be quantified. By crossing the cell operation data with different ex-situ characterisations (pH or conductivity measurements, microscopy images, etc...), the influence of the different components will be deconvoluted, leading to a complete understanding of the HDA operation. Following this, an optimized composition will be proposed with a very competitive operational overpotential versus standard used anode.
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Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,001 | 0,002 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,003 | 0,002 |
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 source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».