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Papers by Wilhelm Schabel

Extended Abstract: Recent developments in the field of lithium-ion battery electrodes are multila... more Extended Abstract: Recent developments in the field of lithium-ion battery electrodes are multilayered, graded coatings with different materials and layer properties. This includes different active materials, additive/binder introduced gradients in each layer but also the coating of a primer layer to increase adhesion and electrical conductivity of the battery layer to the metal current collector foil (see figure 1 for layer structure). In this contribution, improvements of electrode properties due to multilayer electrode configuration will be shown (see also [1], [2]).

Springer Reference Technik, 2019

Die vorliegende Erfindung betrifft eine Vorrichtung fur den Warme- und Stoffubergang, insbesonder... more Die vorliegende Erfindung betrifft eine Vorrichtung fur den Warme- und Stoffubergang, insbesondere zum Trocknen von dunnen Schichten oder Beschichtungen. Im Vordergrund steht hierbei ein Prallstrahlfeld (3) mit hexagonalen Prallstrahldusen (5) und der darum angeordneten Effusionsoffnungen (4). Durch diese Geometrie der Ausstrahl- und Ansaugdusen ergibt sich ein besonders gunstiger Warme-/Stoffubergangskoeffizient bei ausgezeichneter Homogenitat. Daher ist diese Vorrichtung vorteilhaft fur die Trocknung sensibler Bauteile. Weiterhin ist die Vorrichtung gut geeignet fur Abscheideprozesse auf Oberflachen. Daruber hinaus wird eine Trocknungshaube unter Verwendung besagter Vorrichtung vorgeschlagen. Weiterhin betrifft die Erfindung ein Verfahren zur Behandlung von Oberflachenschichten, insbesondere der schonenden Trocknung organischer(opto-)elektronischer Bauteile.

Multicomponent polymer solutions are used in many manufacturing processes, e.g. membrane producti... more Multicomponent polymer solutions are used in many manufacturing processes, e.g. membrane production and optical foils. After deposition, the subsequent drying step has impact on the functionality of the final product. During drying mass transport in the coating is often a limiting factor. Despite the practical relevance, multi-component diffusion in these systems is not yet understood. Especially the mutual influence of different solvent species is theoretically well-known but in practice there are no models to describe this effect properly. The main reason is that it has been almost impossible to determine local solvent concentrations in multicomponent systems. Therefore no experimentally validated theoretical descriptions of multicomponent diffusion exist. Inverse Micro Raman Spectroscopy (IMRS) offers the possibility of in-situ measurement of solvent concentrations in thin films during drying with a high spatial resolution of about 1 to 2 μm and high accuracy.

Apparatus for intermittently coating a substrate located relative to the device in a transport di... more Apparatus for intermittently coating a substrate located relative to the device in a transport direction U in movement, comprising a nozzle body with at least two nozzles jaws, wherein a liner sheet is provided with a recess between the nozzles jaws, wherein the recess in the liner film forms a nozzle slot in the nozzle body, and the die slot transverse to the transport direction U of the substrate and parallel to the substrate extend terminates in an exit gap, wherein the exit slit via the nozzle slot in flow communication with an inlet conduit and a nozzle jaw is provided with at least two openings at least that between the inlet channel and the outlet gap in the nozzle slot open out serially and are each sealed with an elastic deformable member sealing fluid to the nozzle slot out, each elastically deformable element on the one hand with the coating material in Dusensc hlitz and on the other hand, is operatively connected to an actuator in the direction of the nozzle slot, whereb...

Water-based film forming polymer dispersions are often used as environmentally friendly, solvent ... more Water-based film forming polymer dispersions are often used as environmentally friendly, solvent free adhesive systems. These dispersions usually consist of polymer particles, water and surfactants. In the first drying regime the solvent evaporates and particle compaction occurs. When the particles are sufficiently concentrated, they start to coalesce and film formation takes place. The properties of the film are influenced by the drying process. The underlying mechanisms are complex and subject to ongoing scientific investigation. Despite intense research they are not fully understood yet.

In recent years, the demand for high performance and affordable batteries has increased significa... more In recent years, the demand for high performance and affordable batteries has increased significantly, especially in the field of electromobility. In particular, the cost pressure in the production of large battery packs has led to a significant increase in the productivity of electrode manufacturing. Although tape casting has been established as a standard process for manufacturing electrodes for lithium-ion batteries for 30 years, the potential for further improvements in this field has not yet been exhausted. New developments in plant technology and in the materials used offer the possibility of increasing production speed or reducing operating costs, thus creating the conditions for further increases in productivity in the coming years.

Drying Technology

Since the loading of electrodes for Li-ion batteries with an excessive amount of moisture affects... more Since the loading of electrodes for Li-ion batteries with an excessive amount of moisture affects the performance of the cells, the moisture is partly removed in a post-drying process step. The dry...

Journal of Power Sources

Abstract Energy dispersive x-ray spectroscopy (EDS) is evaluated regarding its applicability for ... more Abstract Energy dispersive x-ray spectroscopy (EDS) is evaluated regarding its applicability for revealing the binder distribution in lithium-ion battery electrode films. Graphite anodes comprising carbon black and PVDF binder are subject to varying drying conditions during solvent removal in order to adjust different binder distributions; fluorine is used as a marker for the presence of PVDF. For electrodes of about 70 μm thickness the fluorine concentration is detected at the surface of the electrode film as well as at the interface between electrode film and current collector foil. It is clearly visible by EDS that increasing drying temperatures (and drying rates) result in an accumulation of binder at the surface and a corresponding depletion at the interface. It is demonstrated on the basis of ion-milled cross-sections of thick electrodes (ca. 400 μm) that a quantitative mapping of the binder distribution delivers additional information about concentration gradients in dependence of the drying parameters.

Journal of Power Sources

Abstract In the current work, graphite electrodes comprising PVDF binder and carbon black are sub... more Abstract In the current work, graphite electrodes comprising PVDF binder and carbon black are subjected to characterization. An energy selective backscatter detector is used to localize carbon black and fluorine of PVDF. Therefore, it is necessary to distinguish between graphite, amorphous carbon and fluorine rich regions. Typically, an angular selective backscatter detector is employed to obtain an image providing the material contrast of the sample. Suitable materials for that detector are e.g. alloys to observe intermetallic phases, semiconductor for “channeling contrast”, or imaging SiO2 and Au nanoparticles in biological cells. However, this detector cannot be used to distinguish between light elements with low atomic numbers, such as C to P. In addition, the contrast of fluorine rich regions and graphite is poor in normal in-lens images due to the low difference of the atomic mass between C and F. The aim of this study is to enhance the contrast of fluorine rich regions to graphite to carbon black. Therefore, the energy selective backscatter detector is used and its advantages and setup is described. Finally this technique is applied to investigate 400 μm thick cross-sections of graphite electrodes dried at different temperatures and obtain the carbon black distribution.

Journal of Coatings Technology and Research, 2015

Slot die coating is a film casting process with a highly diverse variety of everyday applications... more Slot die coating is a film casting process with a highly diverse variety of everyday applications. As a pre-metered process it not only guarantees excellent film uniformity, but is also suitable for simultaneously applied multilayer coatings. Characteristic singularities like the behavior of the liquid–liquid interface and the impact of the additional mid-lip on film uniformity were already investigated before. However, the effect of an altered gap pressure regime on commonly used coating windows has not yet been discussed. In this work, we therefore extended available single-layer coating windows for Newtonian and power-law liquids to the bilayer case. Here, the emphasis was laid on the air entrainment limit. Subsequently, the theoretical results were compared to experimental data. It was found that the onset of air entrainment strongly depends on the top to bottom film thickness ratio for bilayer coatings. A critical film thickness ratio which delivers similar coating limits as those for single-layer coatings was derived and confirmed by experimentally gained results.

Springer Reference Technik, 2019

In the light of continuous improvement and optimization, recent experiments that the authors cond... more In the light of continuous improvement and optimization, recent experiments that the authors conducted give new insights into the applied evaluation method of Riegel et al. [1]: Thorough investigations of the previous results regarding the usage of the Lowry Assay showed discrepancies in the determination of the released amount of protein in the analysis solution. The accurate quantification of this parameter is crucial as it directly influences the calculation of the residual enzymatic activity. In concrete terms, this finding has a major impact on the presented and discussed results in the article “Activity determination of FAD‐dependent glucose dehydrogenase immobilized in PEDOT: PSS‐PVA composite films for biosensor applications” [1]. Thus, this commentary addresses the new insights concerning the applied evaluation method, explains necessary revisions and discusses new conclusions derived from the adjusted evaluation method.

Extended Abstract: Recent developments in the field of lithium-ion battery electrodes are multila... more Extended Abstract: Recent developments in the field of lithium-ion battery electrodes are multilayered, graded coatings with different materials and layer properties. This includes different active materials, additive/binder introduced gradients in each layer but also the coating of a primer layer to increase adhesion and electrical conductivity of the battery layer to the metal current collector foil (see figure 1 for layer structure). In this contribution, improvements of electrode properties due to multilayer electrode configuration will be shown (see also [1], [2]).

Springer Reference Technik, 2019

Die vorliegende Erfindung betrifft eine Vorrichtung fur den Warme- und Stoffubergang, insbesonder... more Die vorliegende Erfindung betrifft eine Vorrichtung fur den Warme- und Stoffubergang, insbesondere zum Trocknen von dunnen Schichten oder Beschichtungen. Im Vordergrund steht hierbei ein Prallstrahlfeld (3) mit hexagonalen Prallstrahldusen (5) und der darum angeordneten Effusionsoffnungen (4). Durch diese Geometrie der Ausstrahl- und Ansaugdusen ergibt sich ein besonders gunstiger Warme-/Stoffubergangskoeffizient bei ausgezeichneter Homogenitat. Daher ist diese Vorrichtung vorteilhaft fur die Trocknung sensibler Bauteile. Weiterhin ist die Vorrichtung gut geeignet fur Abscheideprozesse auf Oberflachen. Daruber hinaus wird eine Trocknungshaube unter Verwendung besagter Vorrichtung vorgeschlagen. Weiterhin betrifft die Erfindung ein Verfahren zur Behandlung von Oberflachenschichten, insbesondere der schonenden Trocknung organischer(opto-)elektronischer Bauteile.

Multicomponent polymer solutions are used in many manufacturing processes, e.g. membrane producti... more Multicomponent polymer solutions are used in many manufacturing processes, e.g. membrane production and optical foils. After deposition, the subsequent drying step has impact on the functionality of the final product. During drying mass transport in the coating is often a limiting factor. Despite the practical relevance, multi-component diffusion in these systems is not yet understood. Especially the mutual influence of different solvent species is theoretically well-known but in practice there are no models to describe this effect properly. The main reason is that it has been almost impossible to determine local solvent concentrations in multicomponent systems. Therefore no experimentally validated theoretical descriptions of multicomponent diffusion exist. Inverse Micro Raman Spectroscopy (IMRS) offers the possibility of in-situ measurement of solvent concentrations in thin films during drying with a high spatial resolution of about 1 to 2 μm and high accuracy.

Apparatus for intermittently coating a substrate located relative to the device in a transport di... more Apparatus for intermittently coating a substrate located relative to the device in a transport direction U in movement, comprising a nozzle body with at least two nozzles jaws, wherein a liner sheet is provided with a recess between the nozzles jaws, wherein the recess in the liner film forms a nozzle slot in the nozzle body, and the die slot transverse to the transport direction U of the substrate and parallel to the substrate extend terminates in an exit gap, wherein the exit slit via the nozzle slot in flow communication with an inlet conduit and a nozzle jaw is provided with at least two openings at least that between the inlet channel and the outlet gap in the nozzle slot open out serially and are each sealed with an elastic deformable member sealing fluid to the nozzle slot out, each elastically deformable element on the one hand with the coating material in Dusensc hlitz and on the other hand, is operatively connected to an actuator in the direction of the nozzle slot, whereb...

Water-based film forming polymer dispersions are often used as environmentally friendly, solvent ... more Water-based film forming polymer dispersions are often used as environmentally friendly, solvent free adhesive systems. These dispersions usually consist of polymer particles, water and surfactants. In the first drying regime the solvent evaporates and particle compaction occurs. When the particles are sufficiently concentrated, they start to coalesce and film formation takes place. The properties of the film are influenced by the drying process. The underlying mechanisms are complex and subject to ongoing scientific investigation. Despite intense research they are not fully understood yet.

In recent years, the demand for high performance and affordable batteries has increased significa... more In recent years, the demand for high performance and affordable batteries has increased significantly, especially in the field of electromobility. In particular, the cost pressure in the production of large battery packs has led to a significant increase in the productivity of electrode manufacturing. Although tape casting has been established as a standard process for manufacturing electrodes for lithium-ion batteries for 30 years, the potential for further improvements in this field has not yet been exhausted. New developments in plant technology and in the materials used offer the possibility of increasing production speed or reducing operating costs, thus creating the conditions for further increases in productivity in the coming years.

Drying Technology

Since the loading of electrodes for Li-ion batteries with an excessive amount of moisture affects... more Since the loading of electrodes for Li-ion batteries with an excessive amount of moisture affects the performance of the cells, the moisture is partly removed in a post-drying process step. The dry...

Journal of Power Sources

Abstract Energy dispersive x-ray spectroscopy (EDS) is evaluated regarding its applicability for ... more Abstract Energy dispersive x-ray spectroscopy (EDS) is evaluated regarding its applicability for revealing the binder distribution in lithium-ion battery electrode films. Graphite anodes comprising carbon black and PVDF binder are subject to varying drying conditions during solvent removal in order to adjust different binder distributions; fluorine is used as a marker for the presence of PVDF. For electrodes of about 70 μm thickness the fluorine concentration is detected at the surface of the electrode film as well as at the interface between electrode film and current collector foil. It is clearly visible by EDS that increasing drying temperatures (and drying rates) result in an accumulation of binder at the surface and a corresponding depletion at the interface. It is demonstrated on the basis of ion-milled cross-sections of thick electrodes (ca. 400 μm) that a quantitative mapping of the binder distribution delivers additional information about concentration gradients in dependence of the drying parameters.

Journal of Power Sources

Abstract In the current work, graphite electrodes comprising PVDF binder and carbon black are sub... more Abstract In the current work, graphite electrodes comprising PVDF binder and carbon black are subjected to characterization. An energy selective backscatter detector is used to localize carbon black and fluorine of PVDF. Therefore, it is necessary to distinguish between graphite, amorphous carbon and fluorine rich regions. Typically, an angular selective backscatter detector is employed to obtain an image providing the material contrast of the sample. Suitable materials for that detector are e.g. alloys to observe intermetallic phases, semiconductor for “channeling contrast”, or imaging SiO2 and Au nanoparticles in biological cells. However, this detector cannot be used to distinguish between light elements with low atomic numbers, such as C to P. In addition, the contrast of fluorine rich regions and graphite is poor in normal in-lens images due to the low difference of the atomic mass between C and F. The aim of this study is to enhance the contrast of fluorine rich regions to graphite to carbon black. Therefore, the energy selective backscatter detector is used and its advantages and setup is described. Finally this technique is applied to investigate 400 μm thick cross-sections of graphite electrodes dried at different temperatures and obtain the carbon black distribution.

Journal of Coatings Technology and Research, 2015

Slot die coating is a film casting process with a highly diverse variety of everyday applications... more Slot die coating is a film casting process with a highly diverse variety of everyday applications. As a pre-metered process it not only guarantees excellent film uniformity, but is also suitable for simultaneously applied multilayer coatings. Characteristic singularities like the behavior of the liquid–liquid interface and the impact of the additional mid-lip on film uniformity were already investigated before. However, the effect of an altered gap pressure regime on commonly used coating windows has not yet been discussed. In this work, we therefore extended available single-layer coating windows for Newtonian and power-law liquids to the bilayer case. Here, the emphasis was laid on the air entrainment limit. Subsequently, the theoretical results were compared to experimental data. It was found that the onset of air entrainment strongly depends on the top to bottom film thickness ratio for bilayer coatings. A critical film thickness ratio which delivers similar coating limits as those for single-layer coatings was derived and confirmed by experimentally gained results.

Springer Reference Technik, 2019

In the light of continuous improvement and optimization, recent experiments that the authors cond... more In the light of continuous improvement and optimization, recent experiments that the authors conducted give new insights into the applied evaluation method of Riegel et al. [1]: Thorough investigations of the previous results regarding the usage of the Lowry Assay showed discrepancies in the determination of the released amount of protein in the analysis solution. The accurate quantification of this parameter is crucial as it directly influences the calculation of the residual enzymatic activity. In concrete terms, this finding has a major impact on the presented and discussed results in the article “Activity determination of FAD‐dependent glucose dehydrogenase immobilized in PEDOT: PSS‐PVA composite films for biosensor applications” [1]. Thus, this commentary addresses the new insights concerning the applied evaluation method, explains necessary revisions and discusses new conclusions derived from the adjusted evaluation method.