Final Film Thickness Research Articles

On the role of the porous support membrane in seawater reverse osmosis membrane synthesis, properties and performance

In this study, we explore the role of the polysulfone (PSU) support membrane skin-layer and whole-body pore morphology on the physical-chemical properties and separation performance of hand-cast polyamide-PSU (PA-PSU) composite seawater reverse osmosis (SWRO) membranes. We tailor the support membrane pore morphology by varying the PSU concentration and the coagulation bath temperature. In order to isolate the impacts of the PSU support, all of the porous supports are coated using identical m-phenylene diamine (MPD) and trimesoyl chloride (TMC) solution compositions, reaction conditions, and post-treatments. As PSU concentration increases, PSU support membrane pore size, surface and body porosity, water permeability, MPD mass uptake (by the PSU support), and PA-PSU composite membrane water permeability decrease, while MPD and TMC conversion, PA film mass and thickness, crosslinking degree (XD), and PA-PSU composite membrane NaCl rejection increase. As PSU support membrane coagulation bath temperature increases, support membrane pore size, surface and body porosity, MPD uptake, PA film mass, thickness and XD, MPD and TMC conversion, and NaCl rejection increase, while composite PA-PSU membrane water and NaCl permeability decrease. Composite membrane permeabilities were 70–90 percent of the (theoretical) unsupported PA film permeabilities due to the high XD and low PA coating film thickness. Composite PA-PSU membrane water/salt permeabilities both correlate most strongly with PA coating film mass/thickness and XD, which in turn correlate most strongly with TMC conversion. The key to increasing water permeability is lower PA film mass/thickness and XD with higher support membrane surface pore size and porosity. In contrast, the key to increasing NaCl rejection is higher PA film mass/thickness and XD with lower support membrane surface pore size and porosity.

The dual action of N2 on morphology regulation and mass-transfer acceleration of CO2 hydrate film

The morphology characteristics of CH4, CO2 and CO2+N2 hydrate film forming on the suspending gas bubbles are studied using microscopic visual method at supercooling conditions from 1.0 to 3.0 K. The hydrate film vertical growth rate and thickness along the planar gas-water interface are measured to study the hydrate formation kinetics and mass transfer process. Adding N2 in the gas mixture plays the same role as lowering the supercooling conditions, both retarding the crystal nucleation and growth rates, which results in larger single crystal size and rough hydrate morphology. N2 in the gas mixture helps to delay the secondary nucleation on the hydrate film, which is beneficial to maintain the pore-throat structure and enhance the mass transfer. The vertical growth rate of hydrate film mainly depends on the supercooling conditions and gas compositions but has weak dependence with the experimental temperature and pressure. Under the same gas composition condition, the final film thickness shows a linear relationship with the supercooling conditions. The mass transfer coefficient of CH4 molecules in hydrates ranges from 4.54 to 7.54×10–8 mol·cm–2·s–1·MPa–1. The maximum mass transfer coefficient for CO2+N2 hydrate occurs at the composition of 60% CO2+40% N2, which is 3.98×10–8 mol·cm–2·s–1·MPa–1.

Preparation of PVA/CNTs film with high stability and humidity sensitivity based on multiple process

Polyvinyl alcohol (PVA) is a polyhydroxylated water-soluble polymer with rapid response to water molecules in environment. In this paper, a humidity sensitive PVA film with both high stability and satisfactory humidity sensitivity were prepared based on multiple process, i.e., crosslinking, foaming, spin coating and composition with hydroxylated carbon nanotubes (CNTs). The crosslinking of PVA with formaldehyde enhances the stability of the film under cyclic test condition, which exhibits deviation ratio of 1.1 and 1.2 in response and recovery process respectively. The pore structure generated by foaming agent promotes the water vapor exchange efficiency and improve the humidity response and recovery performance. The spin coating speed significantly influences the pore structure and thickness of the prepared films. CNTs facilitate the dissociation of water molecule through hole carriers and hydroxyl groups to reduce the resistance of PVA/CNTs films and enlarge the humidity response range. The spin coating speed and CNTs content jointly determine the final foaming structure and film thickness. Based on the multiple methods, the obtained crosslinked open pore film exhibits satisfactory humidity sensitive properties with the response time of 48 s and equilibrium time of 296 s, which should have good application prospect.

Numerical simulation and experimental study of dip angle spray film thickness under elliptical double Gaussian sum model

To address the problem of modeling the growth rate of coating film thickness when spraying at inclination angle, based on Gaussian sum model, it is proposed to use the elliptic double Gaussian sum model to establish the cumulative model of coating film thickness when spraying at static inclination angle of the spray gun. The differential geometry amplification theorem is used to establish the coating growth rate model with the spraying inclination angle as the variable; after that, the static inclination spraying experiments are carried out, and the coating thickness data of the sampling points are recorded through the spraying experiments, and the Levenberg-Maquart algorithm is used for the least-squares fitting of the model, which results in the static spraying film thickness distribution model. Finally, compared with the elliptic double β model, the fitting accuracy of the elliptic double Gaussian sum model is 6.3% higher than that of the elliptic double β model when spraying at inclination angle by comparing the R-square values, and the elliptic double Gaussian sum model is more capable of obtaining a better fitting accuracy, which further confirms the validity and practicability of the model.

Dip coating of shear-thinning particulate suspensions.

Dip coating a planar substrate with a suspension of particles in a shear-thinning liquid will entrain particles in the liquid film, facilitating filtration and sorting of particles. Experiments were performed for both monodisperse and bidisperse particle suspensions of shear-thinning Xanthan Gum solutions. Particle entrainment occurs when the coating thickness at the stagnation point of the thin film flow is larger than the particle diameter. A model is developed to predict the entrainment criteria using lubrication theory applied to an Ostwald power-law fluid which yields a modified Landau-Levich-Derjaguin (LLD) law governing the coating film thickness that depends upon a properly defined capillary number Ca. The critical withdrawal velocity for particle entrainment depends upon the particle size and fluid rheology through a relationship between Ca and the bond number Bo, which agrees well with our model predictions and prior experimental results of A. Sauret et al. Phys. Rev. Fluids, 2019, 4, 054303 for the limiting case of Newtonian suspensions. Single particle entrainment and particle clustering is observed for monodisperse suspensions, which depends on Ca and the particle volume fraction ϕ. In bidisperse suspensions, particle sorting can occur whereby only the smaller particles are entrained in the film over an active filtration range of Ca and Bo, which also agrees well with our model predictions.

Interfacial Dynamics Around a Swirling Roller in the Presence of Oppositely Imposed Horizontal Crossflows

Abstract The behavior of interfacial dynamics around a swirling circular drum is reported in the presence of horizontal crossflows of gaseous phase. A constant submergence ratio of the rotary drum is considered throughout this work. Forward and reverse crossflows are defined based on the direction of rotation of drum. A clockwise rotation is imposed on the drum and the rotation direction remains fixed throughout the present investigation. The pattern of film flow and cusp entrainment is observed thoroughly by considering rotational speed (ω) and strength of crossflow as influencing parameters. Strength of crossflow of gaseous phase is calibrated using flow Reynolds number based on roller diameter (Reflow=ρgUD/μg). Subsequently, we characterized the coated film thickness (h*=h/D) and cusp width (H*=H/D) by varying ω and Reflow. Furthermore, efforts are made to observe the influence of gravitational pull (calibrated using Archimedes number, Ar) and viscous drag (determined using Morton number, Mo) on interfacial morphology. The interfacial structures respond more to the rotational inertia compared to crossflow with the continuous increase of Mo. Again, the trailing end of cusp gets widened for the case of forward crossflow, whereas the cusp growth is obstructed in the presence of reverse crossflow, which is visualized using velocity vectors. We have also predicted appropriate correlations for film thickness (h*), cusp width (H*), and steady cusp length (θs*) in the presence of forward as well as reverse crossflow of air stream. Lastly, a theoretical framework is also developed to estimate film thickness and cusp width for both cases of crossflows and this framework agrees well with the simulated predictions.

Material characterization and inter/intra-particle validation for DEM simulation of urea coating process

Particle coating is a common operation in the controlled-release fertilizer (CRF) industry, where a coating layer is appliedto the urea cores. A discrete element method (DEM) computer simulation was applied to model the coating process for the urea granules using measured model parameters. The accuracy of DEM input parameters for the coating material properties and the physical and mechanical characterizations of urea granules are crucial to the study of particle coating processes. Thus, to enhance the simulation accuracy, information on the material properties (urea granules) is required. In this study, the elasticity parameters, shear modulus, coefficient of restitution (CoR), and coefficient of rolling and static friction (CoRF) and (CoSF) of urea granules are estimated experimentally in addition to the physical characteristics. The sensitivity of the angle of repose of the urea bed was investigated at different coefficients of friction. According to the obtained experimental value of the angle of repose, values of 0.2 and 0.3 for CoRF and CoSF, respectively, were adjusted to obtain consistent urea granules’ motion for simulation and the experiment. Moreover, the spray droplet sizes and velocity distributions were estimated using the video-imaging process technique. Based on this experimental characterization, elasticity parameters and spray properties were integrated into DEM simulation software as input data to perform numerical analysis of the coating process to compare simulation and experimental results, which show uniformity at three different pan speeds with a maximum deviation of 0.033 at 5 rpm. Also, consistency between DEM and experiment results was achieved in terms of average coating thickness (μm) of the selected samples and average intra-particle thickness variation (CoVintra). These results revealed that the coating film thickness is proportional to the rotation speed for the experiment and simulation. To enhance the inter-particle coating uniformity, the effects of the most significant parameters such as pan speed, filling ratio, particle size, spray rate, and spray angle, were examined. A low spray rate, filling ratio, and high pan speed improved the coating uniformity. The particle size and spray angle show considerable influence on the coating uniformity, where larger particle sizes and spray angles tend to reduce the inter-particle coating uniformity.

Multiscale Evaluation of Mechanical Properties for Metal-Coated Lattice Structures

With the combination of 3D printing and electroplating technique, metal-coated resin lattice is a viable way to achieve lightweight design with desirable responses. However, due to high structural complexity, mechanical analysis of the macroscopic lattice structure demands high experimental or numerical costs. To efficiently investigate the mechanical behaviors of such structure, in this paper a multiscale numerical method is proposed to study the effective properties of the metal-coated Body-Centered-Cubic (BCC) lattices. Unlike studies of a similar kind in which the effective parameters can be predicted from a single unit cell model, it is noticed that the size effect of representative volume element (RVE) is severe and an insensitive prediction can be only obtained from models containing multiple-unit-cells. To this end, the paper determines the minimum number of unit cells in single RVE. Based on the proposed method that is validated through the experimental comparison, parametric studies are conducted to estimate the impact of strut diameter and coating film thickness on structural responses. It is shown that the increase of volume fraction may improve the elastic modulus and specific modulus remarkably. In contrast, the increase of thickness of coating film only leads to monotonously increased elastic modulus. For this reason, there should be an optimal coating film thickness for the specific modulus of the lattice structure. This work provides an effective method for evaluating structural mechanical properties via the mesoscopic model.

Performance study of CrN coatings prepared by DC magnetron sputtering

Cutting edge declaration strategies and the progression of advanced troublesome coating materials are fundamental for the making of high-quality mechanical components. The point of this work is to induce prepared CrN coatings by magnetron sputtering at unmistakable nitrogen stream rates and to look at the effect of moving nitrogen stream rates on the composition, film thickness and mechanical properties of the gotten chromium nitride coatings. The outcomes appear that the nitrogen stream rate impacts the sputtering rate of the coating, i.e. the affirmation rate diminishes as the degree of nitrogen interior the plasma increments. In expansion, as the nitrogen stream rate increments, the grain gage of the coating diminishes, and the hardness modulus of the coating increments. Flexibility data illustrate that extending the N2 stream rate increases the wear resistance and flexibility of the coating.

Ultra-high-resolution optical coherence tomography for the investigation of thin multilayered pharmaceutical coatings

Optical Coherence Tomography (OCT) has recently gained attention as a promising technology for in-line monitoring of pharmaceutical film-coating processes for (single-layered) tablet coatings and end-point detection with commercial systems. An increasing interest in the investigation of multiparticulate dosage forms with mostly multi-layered coatings below 20 µm final film thickness demands advancement in OCT technology for pharmaceutical imaging. We present an ultra-high-resolution (UHR-) OCT and investigate its performance based on three different multiparticulate dosage forms with different layer structures (one single-layered, two multi-layered) with layer thicknesses in a range from 5 to 50 µm. The achieved system resolution of 2.4 µm (axial) and 3.4 µm (lateral, both in air) enables the assessment of defects, film thickness variability and morphological features within the coating, previously unattainable using OCT. Despite the high transverse resolution, the provided depth of field was found sufficient to reach the core region of all dosage forms under test. We further demonstrate an automated segmentation and evaluation of UHR-OCT images for coating thicknesses, where human experts struggle using today’s standard OCT systems.

Graphene/carbon nanotube/polypyrrole composite films for electromagnetic interference shielding

AbstractPolypyrrole (PPy), an ideal organic electroactive material, shows limited application in the field of electromagnetic interference (EMI) shielding for its relatively low shielding effectiveness (SE), significant stiffness, difficult solubility, and poor processing performance. A strategy is proposed to construct three‐dimensional network structures of graphene/CNT/polypyrrole by electrochemical deposition to improve the EMI SE of polypyrrole composite films. In the graphene/CNT/polypyrrole films, the graphene/CNT substrates form the skeletons, and polypyrrole acts as bridges between graphene sheets and CNTs to form percolation networks in the multiphase and multihierarchical nanocomposites. When the deposition time increases to 80 min, the content of polypyrrole increases to 30 wt%, the conductivity improves by 27.7%, and the EMI SE improves by 11.4% at X‐band. The final film thickness is 249 μm, the conductivity is 3.06 S/mm, and the average EMI SE is 59.6 dB.

Antibacterial coating of corona treated Poly(lactic acid) / Poly(butylene succinate) film with Chitosan and Zinc oxide nanoparticle

The biodegradable PLA/PBS 90/10 wt% films were extruded and surface treated with corona discharge. Two electrical inputs of the corona treatment were used, 2 or 6 amperes, which the change of the surface tension was evaluated using corona measuring pens. The blend films were coated with the antibacterial mixture between chitosan and zinc oxide nanoparticles (ZnO-NP) in four concentrations: 1.0/0.4, 1.0/0.5, 1.5/0.5, and 1.5/0.5 wt%/wt%. This film could be used to replace transparent disposable packaging in the circular economy. It was found that the surface tension of the blend film was 30 dyne (mN/m) which was much like the neat PLA due to PLA being the main composition. Since the overall coated film thickness was kept constant, there was no significant difference in the coating weight among four coating concentrations. Compared to the uncoated PLA/PBS film, the tensile strength of the coated films tended to be higher with the increase of ZnO-NP content. However, the elongation at break of the coated films decreased significantly, which the stiffer coating layers became the stress concentrators. From SEM, it was seen that the good adhesion between the polymer and the coating layer was achieved. When the coated films were torn apart in the trouser tear testing, the failure was the breakage of the blend film with there was some coating layer delaminated.

Application and characterization of a novel PVDF-HFP/PVP polymer composite with MoO3 nanowires as a protective coating for wood

The coatings on wood must sometimes give aesthetic and basic protection to wooden elements and prevent the development and transmission of microorganisms. Several polymers containing different nanoparticles have already been offered to day for this purpose. The research presents a novel poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/polyvinylpyrrolidone (PVP) polymer composite with MoO3 nanowires with the ability to form coating films on wood. The films of the developed coating exhibit elastic behaviour, which depends on the coating film thickness [tested wet film thicknesses (90, 180 and 360) µm]. The coating showed the ability to interact well with the surface of common beech (Fagus sylvatica L.) wood, in terms of wetting (contact angles of 15.6°), fast spilling on the surface, good penetration of the coating in wood structure and formation of up to 40 µm-thick films with excellent pull-off adhesion strength (6 MPa). An increased roughness of wood coated with C + MoO3 was a consequence of wood etching by the dimethylformamide solvent present in the coating. Moreover, the presence of C + MoO3 on wood made it considerably more hydrophobic, with contact angle of water raising to 123° from initially 46° measured on uncoated wood. The irradiation of wood surfaces with ultra-violet light resulted in visible colour changes on both uncoated and coated wood. The wood coated with C + MoO3 has a good resistance to water, alcohol and dry heat (grade 3 to 4). The antimicrobial testing showed that the presence of MoO3 in the coating plays an important role in the resistance of the coated wood to blue-stain fungi and mould development. The developed PVDF-HFP/PVP/MoO3 coating has an excellent ability to interact with the wood surface and has the potential to be used as a protection for wood in sensitive environments.

Development and optimisation of a SiO2 PVD technique based on the thermal decomposition of PDMS

Mass and heat rate dependant deposition of SiO2 vapour species by controlled thermal degradation of PDMS on solid substrates.

Effects of Co-Solvent-Induced Self-Assembled Graphene-PVDF Composite Film on Piezoelectric Application

A persistent purpose for self-powered and wearable electronic devices is the fabrication of graphene-PVDF piezoelectric nanogenerators with various co-solvents that could provide enhanced levels of durability and stability while generating a higher output. This study resulted in a piezoelectric nanogenerator based on a composite film composed of graphene, and poly (vinylidene fluoride) (PVDF) as a flexible polymer matrix that delivers high performance, flexibility, and cost-effectiveness. By adjusting the co-solvent in the solution, a graphene-PVDF piezoelectric nanogenerator can be created (acetone, THF, water, and EtOH). The solution becomes less viscous and is more diluted the more significant the concentration of co-solvents, such as acetone, THF, and EtOH. Additionally, when the density is low, the thickness will be thinner. The final film thickness for all is ~25 µm. Furthermore, the- crystal phase becomes more apparent when graphene is added and combined with the four co-solvents. Based on the XRD results, the peak changes to the right, which can be inferred to be more dominant with the β-phase. THF is the co-solvent with the highest piezoelectric output among other co-solvents. Most of the output voltages produced are 0.071 V and are more significant than the rest.

Nanodroplet wetting and electrowetting behavior on liquid-infused surfaces: A molecular simulation study

Due to the block of the lubricant on liquid-infused surfaces (LISs), the molecular processes near the liquid-liquid interface and the shape ofdropletunderelectrowetting actuation are still difficult to observe with simple optical methods. Molecular dynamics (MD) simulation provides a visual method for observing the nanodroplet morphology on the LISs. In this paper, the impacts of the substrate characteristics and the lubricant thickness on the cloaking state, the wetting state and the diffusion diameter of nanodroplet were studied by the MD simulation. It is found the coating film of the nanodroplet increases with the lubricant layer thickness on the LISs of silicon nanopillarsubstrate, while the nanodroplet is always in the not cloaking state on the LISs of copper nanopillarsubstrate, even with a very thick lubricant layer. Subsequently, the electrowetting behaviors of the nanodroplet under the external electric field in the parallel and perpendicular directions to the surface were studied. The results indicate the droplet changes from the Cassie state to the partial Wenzel state under the influence of the external electric field on the LISs of both substrates. Meanwhile, the coating film thickness increases with the electric field intensity, the nanodroplet changes from a not cloaking state to a cloaking state on the LISs of copper substrate, while still is in a not cloaking state on the LISs of silicon substrate. Compared to the LISs of the silicon substrate, the electro-stretching is easier to happen on the LISs of the copper substrate. Finally, the impact of lubricant layer thickness on the nanodroplet electrowetting was studied on both copper and silicon substrates. It is found the reduction of nanodroplet apparent contact angle increases with the lubricant layer thickness under an external parallel electric field, while it has a maximum on the moderate lubricant thickness under an external electric field in a perpendicular upward or downward direction. Our results indicate the droplet deformation on LISs under the external electric field is contributed to the competition of the electrowetting, the electro-stretching, and the pinning effect.

Enhancing the anti-corrosion performance and biocompatibility of AZ91D Mg alloy by applying roughness pretreatment and coating with in-situ Mg(OH)2/Mg-Al LDH

Corrosion-resistant and biocompatible films were fabricated on AZ91D Mg alloy substrates by varying their roughness levels using metallographic preparation and subsequent hydrothermal procedures. The coated films comprised a mixed structure of Mg(OH)2 and Mg-Al layered double hydroxides (LDH) and exhibited excellent compactness. Coating film thickness increased with decreasing surface roughness. Corrosion resistance was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy. Metallographic pretreatment influenced the chemical activity of the Mg alloy surface and helped modulate the dissolution rate of the Mg17Al12 phase during the hydrothermal procedure. With decreasing roughness of the Mg substrate, the Al3+ concentration gradually increased, accelerating the in-situ formation of the Mg(OH)2/LDH composite coating and improving its crystallinity. A thick and dense Mg(OH)2/LDH coating was synthesized on the Mg substrate with the least roughness, substantially improving the corrosion resistance of the AZ91D alloy. The lowest corrosion current density ((5.73 ± 2.75) × 10−8 A·cm−2) was achieved, which was approximately three orders of magnitude less than that of bare AZ91D. Moreover, the coating demonstrated biocompatibility with no evident cytotoxicity, cellular damage, and hemolytic phenomena. This study provides an effective method for preparing coatings on Mg alloy surfaces with excellent corrosion resistance and biocompatibility.

Blade coating analysis of carreau fluid model with Magnetohydrodynamics and slip effects

Coating is a process that improves and enhances life, quality and efficiency of the web. Common industrial adhesive application to board and paper, metal foils polymer coatings, photographic film emulsions, recording films, textile fabrics, paints, coating on food items, medicine, catalogues are common examples. There are many fluids that are used as coatings. This paper analyses blade coating using both plane as well as exponential geometries along with slip and magnetohydrodynamics effects for a Carreau fluid model. To study the blade coating phenomenon, slip is introduced at the blade surface and a magnetic field is applied normal to the fluid flow. The LAT (Lubrication approximation theory) has been introduced to convert governing partial differential equations into a simpler form and a numerical solution is obtained by using shooting method. The significant physical quantities like volumetric flow rate, pressure, velocity, load, coated film thickness and pressure gradient are discussed in detail. The effects of power law index, slip parameter, Weissenberg number and Hartmann number on these physical quantities are presented. The observations are depicted in tabular data and in the graphical form as well. The Weissenberg number and Hartmann number play a very important role in controlling the load and coated film thickness.

Characterization and Model-Based Investigation of Lithium-Ion Battery Cell Formation

The formation process of lithium-ion battery cells is one of the main contributors to the overall cell cost [1]. During this process step the solid electrolyte interface (SEI) is initially built. It is agreed upon that the composition and morphology of the SEI influences the safety and aging behaviour of the battery cell. However, the processes behind the initial build-up are not fully understood due to the manifold influencing factors, such as electrolyte composition, electrode structure, temperature, and formation protocol, which all impact the complex nanoscale processes at the interface [2,3,4]. High experimental effort is needed to investigate and optimize this process. Detailed multiscale models based on first principles can provide insights into the SEI formation but require many parameters that are difficult to determine and are also associated with uncertainty [5,6]. Therefore, those approaches are limited in terms of exploration and optimization of the formation process. Hence, there is a need for novel methods that enable to obtain information about the SEI growth and investigate the influential factors to effectively accelerate the development process. Here, we suggest a model-based approach that uses lumped growth models that can quickly be identified by using differential voltage data of formation experiments. Further, models are applied to simulate the impact of the formation protocol on the SEI formation with minimal experimental effort.Firstly, we present a parameter identification process for the applied growth model, which is based on a slow formation protocol and a reference measurement in a 3-electrode setup. The parameterization of the SEI model is conducted by combining coulometry and differential voltage analysis (DVA). Shifts of distinct peaks, i.e. feature, within the anode potential curve during the formation and the reference measurement are used to deduce the capacity loss due to the SEI growth. Using the SEI density and surface area of the electrode, the capacity loss is converted into an effective layer thickness, which is used to fit the parameters of the growth model. Within the SEI model different growth mechanisms can be implemented and compared. It is demonstrated that this approach can show differences in the SEI formation for a variation of electrolyte compositions, i.e. the electrolyte additives as can be seen in Figure 1. Afterwards, a simulation study for different formation protocols is presented. The identified growth model has been coupled with a pseudo-2-dimensional (P2D) model. Simulations are also compared to experimental data for various formation protocols and are shown to be in good agreement. Simulations reveal that the final effective film thickness is only slightly affected by current magnitude and mainly depends on the formation time as well as the anode potential. Furthermore, it can be seen that higher formation currents affect the homogeneity of the SEI across the electrode negatively.To sum up, the DVA analysis of the formation yields information about the SEI growth. This can be used to parametrize SEI growth models and investigate film growth mechanisms for different electrolyte compositions. Coupling growth models with P2D models enables to explore the influence of the formation protocols. To conclude, this novel approach enables to significantly accelerate the optimization of battery cell formation. In future work the approach could be refined to enable application to full cell voltage data, which would allow its use within battery production lines and could support end of line testing.[1] A. Kwade, W. Haselrieder, R. Leithoff, A. Modlinger, F. Dietrich, K. Dröder, Current status and challenges for automotive battery production technologies, Nature Energy, 2018, 3, DOI: 10.1038/s41560-018-0130-3[2] G. E. Blomgren, Liquid electrolytes for lithium and lithium-ion batteries, Journal of Power Sources, 2003, 119, DOI: 10.1016/S0378-7753(03)00147-2[3] S. J. An, J. Li, C. Daniel, D. Mohanty, S. Nagpure, D. L. Wood, The state of understanding of the lithium-ion-battery graphite solid electrolyte interphase (SEI) and its relationship to formation cycling, Carbon, 2016, 105, DOI: 10.1016/j.carbon.2016.04.008.[4] K. Xu, Electrolytes and interphases in Li-ion batteries and beyond, Chemical reviews, 2014, 114(23), DOI: 10.1021/cr500003w.[5] A. Wang, S. Kadam, H. Li, S. Shi, Y. Qi, Review on modeling of the anode solid electrolyte interphase (SEI) for lithium-ion batteries, npj Computational Materials, 2018, 4, DOI: 10.1038/s41524-018-0064-0[6] F. Röder, R. D. Braatz, U. Krewer, Multi-scale simulation of heterogeneous surface film growth mechanisms in lithium-ion batteries, Journal of the Electrochemical Society, 2017, 164 (11), DOI: 10.1149/2.0241711jes. Figure 1

Effects of Wet Film Application Parameters on the Structure and Performance of Fuel Cell Catalyst Layers Prepared Using Scalable Methods

The use of high-volume manufacturing processes for polymer electrolyte fuel cells is obligatory to bring the manufacturing cost closer to 80USD/kW fuel cell system cost target for long-Haul Trucks [1] and thereby make this technology an economical competitor in the carbon neutral transportation sector. For the membrane electrode assembly, thin film roll good materials are therefore the norm in the industry. On the lab scale however, catalyst layers and catalyst coated membranes (CCMs) are commonly prepared with low throughput multi-sub-layer coating application techniques, such as ultrasonic spray coating. Overall, each catalyst sub-layer is dried before the next sub-layer is applied via another spraying pass, until the desired catalyst loading and therewith the overall catalyst layer is created. This multi-sub-layer coating approach is therefore time consuming.However, to simulate high volume manufacturing at the lab scale, direct layer coating techniques such as film applicator or Mayer bar coating can be utilized. These coating methods are designed to form a one pass final catalyst wet film thickness, similar to what transpires in a continuous high throughput roll to roll (R-2-R) manufacturing process. As opposed to the multi-layer coating techniques, the entire wet thickness of the catalyst layer is dried in one step, which allows greater throughput, but also influences the catalyst layer formation. Because when a catalyst wet film dries, there are forces related to evaporation, diffusion, and sedimentation which influence the distribution of materials and the ultimate catalyst layer structure [2]. Furthermore, catalyst inks used for Mayer-rod, film applicator, and R-2-R coating methods generally have higher solids content than the inks used in spray coating. With the one pass techniques, CCMs are typically fabricated by coating catalyst ink on a decal film, such as polytetrafluoroethylene (PTFE), followed by a hot lamination process, such as decal transfer, of the catalyst layer to the membrane [3]. Due to the interaction of the catalyst ink with the coating substrate and drying process, there are many factors that may influence the quality of the catalyst layer obtained with direct layer coating, considering both ink formulation and coating parameters.To understand the interaction of these influences, we investigate the effects of wet film application parameters on the structure and performance of fuel cell catalyst layers, prepared using scalable methods. The same drying technique of hot air drying is used to obtain a closer representation of the direct layer R-2-R process. In more detail, we are determining the influence of the following factors on the catalyst layer formation, when coated on a PTFE substrate: drying temperature, ionomer-to-carbon support ratio, ink water-to-alcohol ratio, and wet film thickness for each of the two-lab scale direct layer coating methods. Finally, we will discuss the influence of these factors on the catalyst structure via microscopy. As well as performance and electrochemical analysis data, of selected catalyst layers, after being decal transferred onto a membrane and tested.Figure 1 shows an example of the variance of dried catalyst layers coated via two direct coating methods on PTFE substrates from the alterations of Ink Water-to-Alcohol (2-Propanol, 1-Propanol, Ethanol) ratio and coating wet thicknesses. As can be seen the dried catalyst layer structure vary depending on the Ink Water-to-Alcohol ratio, wet thickness and application method used. Acknowledgments This research was supported by the Simon Fraser University Community Trust Endowment Fund, Natural Sciences and Engineering Research Council of Canada, Canada Foundation for Innovation, British Columbia Knowledge Development Fund, Western Economic Diversification Canada, and Canada Research Chairs. Reference [1] Menezes, Mark W., et al. “"US Department of Energy Hydrogen Program Plan” https://www.hydrogen.energy.gov/roadmaps_vision.html (2020)[2] C.M. Cardinal, Y.D. Jung, K.H. Ahn, L.F. Francis, Drying regime maps for particulate coatings, AIChE J. 56 (2010) 2769–2780, https://doi.org/10.1002/ aic.12190.[3] Wei, Zhaoxu, et al., High performance polymer electrolyte membrane fuel cells (PEMFCs) with gradient Pt nanowire cathodes prepared by decal transfer method. International Journal of Hydrogen Energy 40.7 (2015): 3068-3074. Figure 1