Characterization of Inkjet Printed Electrodes with Improved Porosity
Notice bibliographique
Résumé
Since a considerable amount of polymer electrolyte fuel cell (PEFC) stack cost is associated with platinum (Pt) that serves as a catalyst, reduction of Pt loading in the catalyst layers (CLs) without affecting the performance is a major research goal of the fuel cell industry. One of the essential factors affecting the Pt loading in the CLs is the fabrication technique used. Inkjet printing (IJP) is one such technique that can produce CLs with low Pt loading and a high Pt utilization [1-3]. However, a drawback for the IJP CLs, was found to be a reduction in porosity at higher Pt loadings, which corresponds to the increased number of deposited layers [2]. This was a major limiting factor affecting the performance of IJP electrodes, when comparing to conventionally fabricated electrodes [2]. In this work, a modified catalyst ink formulation is used, resulting in CLs that have a higher porosity compared to previous layers. Further, a methodology to determine the CL porosity, based on Archimedes law, is reported. The catalyst ink consisted of 50 wt. % Pt/C catalyst dispersed in a mixture of Isopropanol, 5 wt. % ionomer solution and a diol solvent to increase the ink viscosity. The improvement in porosity was achieved using a higher volatility solvent in the ink. A Fujifilm Dimatix inkjet printer was used for the CL fabrication process. Details regarding the fabrication process can be found in our earlier work [2]. The Pt loading in the CLs was determined by X-ray fluorescence analyzer (Themo Scientific Niton XL3t). The target Pt loading was 0.15 mg/cm2, corresponding to approximately 16 printed layers. For comparison, electrodes using the previous ink recipe were also fabricated and analyzed [2]. The CLs were imaged using a laser scanning microscope to estimate the crack density and a scanning electron microscope (SEM) to determine the CL thickness. In-situ characterization of the electrodes was done in a 40 cm 2 cell to compare the performance at different conditions, electrochemical active area and oxygen transport resistance using AFCC testing protocols. For determination of CL porosity, a commercially available density determination kit (Sartorius mechatronics) was modified in-house and used in tandem with a Python based GUI to monitor the sample weight. The setup resembled the one reported by Rashapov et al. [4]. A PTFE substrate was used for the CLs when measuring porosity. Weight of the sample (CL + substrate) was taken in air, n-octane and deionized water. The total pore volume is obtained with the hypothesis that octane intrudes all the pores in the sample, thus reflecting its solid volume fraction, whereas water does not intrude any pores owing to its high surface tension, reflecting the CL bulk volume. To reduce the measurement error, an average of at least three weight readings was taken in each medium. The overall porosity of the IJP CL using the modified recipe was found to be 69.5±2.3 % compared to 51.3±2.2 % using the previous ink recipe, indicating a substantial improvement in the porosity [2]. This is reflected in the preliminary in-situ testing where a gain between 20 – 50 mV is achieved at different operating conditions compared to previous IJP electrodes. CLs using the modified ink recipe showed a power density of 1 W/cm 2 at 0.6 V at normal operating conditions (68 0 C, 70% RH), indicating that inkjet printing appears to be a feasible technique for electrode fabrication. Further testing of the CLs is underway. References: 1. Shukla, S., Domican, K., Karan, K., Bhattacharjee, S., & Secanell, M. Electrochimica Acta , 156 , 289-300 (2015) 2. Shukla, S., Stanier, D., Saha, M. S., Stumper, J., & Secanell, M. Journal of The Electrochemical Society , 163 (7), F677-F687 (2016) 3. Saha, M. S., Malevich, D., Halliop, E., Pharoah, J. G., Peppley, B. A., & Karan, K. Journal of The Electrochemical Society , 158 (5), B562-B567 (2011) 4. Rashapov, R. R., Unno, J., & Gostick, J. T. Journal of The Electrochemical Society , 162 (6), F603-F612 (2015) Figure 1
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
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 | 0,000 | 0,000 |
| 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.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».