A distinctive field in the coatings industry is the coating of porous media, with broad applications in paper, apparel, textile, electronics, bioengineering, filtration and energy sector. A primary industrial scale process that can be used to coat porous media in a fast and flexible manner is slot die extrusion. A major concern when coating porous media with a wetting fluid is fluid penetration into the substrate. Although some level of penetration is desirable to obtain specific material properties, inadequate or excessive fluid penetration can negatively affect the strength, functionality or performance of the resulting material. In spite of its apparent industrial importance, limited modeling and experimental work has been conducted to study fluid penetration into porous media during fabrication. The effects of processing parameters on the penetration depth, the effects of penetration on material quality, and the method to predict and control the penetration depth are not well understood. This dissertation is composed of two parts. Part I is an applied study for coating onto porous media. This part focuses on the first objective of this dissertation which is to elucidate clearly the feasibility, advantages and disadvantages of the direct coating method as a potential fabrication route for membrane electrode assembly (MEA). MEA samples are fabricated using both traditional and the direct coating methods. Then, the quality and performance of the MEA samples are examined. Experimental results in Part I demonstrate that it is feasible to fabricate MEAs using the direct coating method. However, Nafion® solution penetrates into the catalyst layer during the coating process and causes lower performance of fuel cells, which is the motivation for Part II of this thesis. The objective of Part II is to fundamentally understand the fluid penetration process and predict the penetration depth when directly coating porous media, using a comprehensive approach. A series of computational and analytical models are developed to predict the penetration depth for both Newtonian and non-Newtonian fluids with or without capillary pressure. Finally the accuracy of developed models are validated through experiments. The relative error between the predicted and experimentally measured penetration depth is generally lower than 20%.

In dieser Dissertation wird eine umfassende Untersuchung von Perowskit-Tintenformulierungen für die Herstellung von hocheffizienten MAPbI3- und FAPbI3-Bauelementen durchgeführt. Darüber hinaus schlagen wir einen kombinatorischen Slot-Die-Beschichtungsansatz für das Screening und die Herstellung von Perowskit-Zusammensetzungen vor. Diese Ergebnisse zeigen, dass die Slot-Die-Beschichtung eine vielversprechende Technik für die Hochskalierung von Metallhalogenid-Perowskit-Dünnschichten ist. / This dissertation gives a comprehensive investigation into perovskite ink formulations for the fabrication of highly efficient MAPbI3 and FAPbI3 devices. Additionally, we propose a combinatorial slot-die coating approach for screening and fabricating perovskite compositions. These results demonstrate that slot-die coating is a promising technique for the upscaling of metal-halide perovskite thin-films.

Defect generation and propagation in thin films, such as separation membranes, can lead to premature or catastrophic failure of devices such as polymer electrolyte membrane fuel cells (PEMFC). It is hypothesized that defects (e.g., air bubbles, pin-holes, and holes) originate during the manufacturing stage, if precise control is not maintained over the coating process, and they propagate during system operation. Experimental and numerical studies were performed to detect and eliminate defects that were induced during slot die coating of high-viscosity (1 to 40 Pa-s), shear-thinning solutions. The effects of fluid properties, geometric parameters and processing conditions on air entrainment and coating windows (limited set of processing conditions for which defect-free coating exists) were studied. When smaller slot gaps and coating gaps were used, relatively small bubbles were entrained in the coated film. The air bubble sizes increased as the viscosity of the coating solution decreased. A semi-empirical model correlating the maximum coating speed to a solution's material properties, geometric parameters and processing conditions was developed. Such a predictive model will enable engineers to determine the maximum coating boundary for shear-thinning and Newtonian solutions within certain constraints. Smaller coating gaps and low-viscosity solutions produced higher coating speeds. The surface tension property of the coating solution provided stability to the coating bead. Therefore, solutions with higher surface tension could be processed at higher coating speeds.

Lithium-ion batteries (LIB) represent a promising energy storage solution in the pursuit of electrification to combat climate change. In order for LIBs to be used across different industries, they have to be commercially viable. The viability for manufacturing LIBs at scale is increasing, with manufacturing costs decreasing 89% in the last ten years. However, the LIB manufacturing process is complex and can generate large amounts of scrap due to various non-conformities (NCs). Therefore, to further increase the ability to manufacture high-quality LIBs at scale, it is crucial to minimize the occurrence of NCs by understanding their root causes. This thesis examines the characteristics of one of the non-conformities occurring in the electrode coating process, namely the formation of craters on the coated surface of the anode electrode. The thesis was conducted at Northvolt Labs using a DMAIC approach to establish relationships between various process parameters and the formation of craters in two processes, coating, and its precursor process, slurry mixing. Utilizing the data models linear regression, CART regression, regularized linear regression, and a slurry experiment, process parameters and characteristics that affect crater formation were identified. Firstly, from the data models, it was distinguished that the speed of the supply pump used in transferring the slurry from the supply tank to the slot die, and the pressure in the filter pump, have the largest effect on crater formation. Further, the time that the slurry spends in storage, i.e. from a completely mixed slurry batch to it being applied in coating, affects crater formation. In this case, the longer the slurry is stored, the more craters are found. Another notable result is that refilling the coating supply tank induces crater formation. The mentioned results indicate that the various stages of slurry transfer undertaken before coating can result in advantageous conditions for craters to form. Moreover, it was discovered that changes in the loading level of the coated anode surface can indicate crater formation. The slurry experiment discovered that by contaminating the slurry with lubricant grease, NCs with similar characteristics to the crater could be generated. While not likely related to craters, this result provides valuable insights for slurry contamination. In addition to the data models and experiments, actions to facilitate future statistical analysis investigations are proposed. This thesis also proposes actions that can be undertaken to potentially mitigate the formation of craters. Suggested actions include methods to investigate the optimal storage time of the slurry before used in coating. Further, we recommend that the coating process should be monitored through the use of control charts on the loading level measurements of the coated surface. Consequently, large changes in loading level can be detected, entailing potential crater formation. We also propose adding lubricant grease as a potential risk in the PFMEA Northvolt uses for process risk evaluation. This recommendation is also complemented with suggested actions on how to handle the risks of lubricant grease contamination. / Användandet av litiumjonbatterier (LIB) som energilagring är en potentiell lösning för omställning till ett elektrifierat samhälle. Tillverkningsprocessen för LIBs är dock komplex och har en tendens att generera stora mängder kassationer på grund av olika typer av defekter. Denna studie ämnar att undersöka egenskaperna hos en av defekterna som kallas krater som kan förekomma i en av delprocesserna för litiumjonbatteritillverkning, elektrodbeläggning, där batteriets elektroder skapas genom att en blandning av aktiva material appliceras på en metallfolie. Kratern förekommer som en cirkulär form på den belagda ytan av anodelektroden. Studien genomfördes hos batteritillverkaren Northvolt Labs och använde en struktur enligt DMAIC cykeln. Syftet med studien var att fastställa samband mellan olika processparametrar och kraterformation för två olika processer, elektrodbeläggning och dess föregångare, framställning av den aktiva materialblandningen. Genom att använda datamodellerna linjär regression, CART-regression, en regulariserad linjär regression  samt ett experiment kunde processparametrar och egenskaper som påverkar kraterbildningen etableras. Resultaten från datamodellerna indikerar att varvtalet i pumpen som tillför ytbeläggningsmaskinen med den aktiva materialblandningen samt trycket i filterpumpen har den största effekten på kraterbildning. Vidare så påverkar tiden som den aktiva materialblandningen lagras innan den används i beläggningsprocessen. Resultaten indikerar att ju längre tid en aktiv materialblandning lagras, desto mer kraterbildning. Samtliga resultat som nämnts ovan anvisar att de olika stadier den aktiva materialblandningen överförs bland olika behållare och verktyg kan ge upphov till kraterbildning. Ytterligare resultat från datamodellerna indikerar att en minskad tjocklek av den belagda ytan, mätt med enheten g/cm2, kan påvisa när kratrar uppstår. Detta resultat kan härledas till att kratrarna orsakar en nedåtbuktning i den belagda ytan. Utifrån experimentet med den aktiva materialblandningen kunde det fastlås att kraterliknande defekter kunde genereras genom att kontaminera blandningen med smörjfett. Dessa defekter är sannolikt inte besläktade med kratern, men dess uppkomst ger värdefulla insikter hur kontaminering kan påverka kvaliteten på den belagda ytan. Utöver resultat från datamodellerna och experimentet så presenterar även denna studie förslag på hur framtida undersökningar av statistisk karaktär kan förbättras. Studien föreslår också konkreta åtanganden som kan genomföras med syfte att reducera kraterbildning. Detta inkluderar hur ett projekt med syfte att fastslå den optimala lagringstiden för den aktiva materialblandningen innan den används i ytbeläggningsprocessen kan utformas. Vidare rekommenderas att ytbeläggningsprocessen övervakas med hjälp av att upprätta styrdiagram för ytbeläggningens nivåförändringar. Följaktligen kan stora förändringar i ytbeläggningens jämnhet detekteras, vilket kan vara en indikator på kraterbildning. Studien rekommenderar också att tillägga kontaminering av smörjfett i den aktiva materialblandningen som en potentiell risk i Northvolts PFMEA. Denna rekommendation kompletteras även med förslag på åtanganden som kan tas för att hantera risken för kontaminering av smörjfett.

This diploma thesis deals with material printing using roll to roll material printer. Several kinds of printing inks were prepared and their parameters, like viscosity and homogeneity were optimized. Corona treated PET foil was used as the flexible substrate. Thin layers of function material were prepared by coating by using the smooth cylinder and slot die method. Layers homogeneity was characterized by optical density. Layer thickness was measured by profilometer.