Process arrangement for the production of an electrode coating

Abstract

The invention relates to a process arrangement for manufacturing an electrode coating (1) on a carrier film (3) for an electrode of a battery cell, comprising a slurry reservoir (5) in which a slurry (7) consisting of powdered active material, solvent, binder, and additives is stored, and an application tool (13) which is in flow communication with the slurry reservoir (5), wherein the slurry (7) can be applied to the carrier film (3) by means of the application tool (13) to form the electrode coating (1). According to the invention, the process arrangement includes at least one polarimeter (27) with which a slurry composition, in particular the solids content, gas inclusions (45), and / or impurities (51), can be monitored in an inline process measurement during the manufacturing process.

Description

[0001] The invention relates to a process arrangement for manufacturing an electrode coating on a carrier film for an electrode of a battery cell according to the preamble of claim 1.

[0002] Such a generic process arrangement has a slurry reservoir in which a slurry consisting of powdered solid active material, solvent, binder and additives is held. In addition, the process arrangement has an application tool which is in fluid connection with the slurry reservoir. With the aid of the application tool, the slurry, that is to say a viscous paste which forms the starting component of the electrode coating, is applied to the carrier film to form the electrode coating.

[0003] The invention is based on the following problems. A first problem is sedimentation during the storage of slurry, i.e., the viscous starting component of the active material. During a mixing process, the active material is mixed with a solvent so that the active material is evenly distributed in the solvent. After the mixing process, the slurry is transferred to a storage tank and from there piped to the coating machine. In the storage tank, the slurry is constantly circulated at 20 to 30 revolutions per minute to prevent sedimentation. However, such sedimentation cannot be completely prevented, so it affects the solids content of the slurry at different levels in the storage tank. If the slurry reaches the coating with different solids contents, the mass loading of the active material is not uniform, and thus the capacity of the electrode is not uniform either.With the varying solid content of the slurry, its viscosity would also change, which would also lead to uneven coating thickness. During the coating process, there is no mechanism for inline control of the slurry's solid content. The coating speed is approximately 70 to 120 m / min, which makes it difficult to respond quickly to changes in the slurry.

[0004] Visual inspection, X-ray, or ultrasonic thickness measurement would not be able to distinguish the slurry based on its varying solids content. Beta rays could provide evidence of uneven feeding after coating, but not during the coating phase. Therefore, current control systems are unable to predict these defects in the coating line. It is assumed that the carbon black content measured in the slurry remains constant for at least two days before being added to the storage tank, during which time the slurry should be consumed. However, constancy or homogeneity of the slurry composition cannot be maintained because sedimentation occurs over time. The active material is not completely soluble in the solvent, and finally, two days of slurry shelf life is sometimes insufficient when the coating machine is undergoing maintenance or repair.In this case, a longer shelf life is desired, although strong sedimentation is to be expected.

[0005] A second challenge concerns impurities in the slurry that cannot be removed by magnetic filters alone. Active material contains many impurities and coarse undissolved particles, which are removed by passing the slurry through magnetic filters and mesh filters. These filters attempt to reduce defects; however, due to the fact that the filter pores eventually close and the magnetic strength decreases, it is not always possible to remove impurities and undissolved particles. These eventually penetrate the coating and are deposited on the electrode. Inline control of these materials using an optical system is impossible because these particles are also black and cannot be distinguished from the color of the slurry. Manganese-containing metallic impurities such as iron can cause a short circuit and the self-discharge of the battery.In addition, undissolved active material particles are not firmly bonded to the slurry and can lead to delamination.

[0006] A third problem area concerns gas evolution and air entrapment during slurry storage and transport. The reaction of active material with the solvent leads to gas formation, which is a continuous process. Despite degassing in the storage tank, gas entrapment is unavoidable. Sometimes the gas is also trapped in the slurry during transport through pipes. These gas or air entrapments lead to holes in the slurry. There is currently no way to eliminate these defects. The only option is to preventively remove coated areas with holes, which are detected with a camera after calendering. This can lead to high material waste. In this case, in addition to the active material, foils such as copper and aluminum are also scrapped, which further increases scrap costs.

[0007] A fourth problem is that the properties of a double-sided coated electrode, i.e., a multilayer coating, are difficult to control. Anodes can be coated with different active material layers on both sides. For example, the active material layer on the outside of the stack of a stacked-end anode may have a high binder content, while the active material layer on the inside of the stack may have a low binder content. Currently, the coating of the anode substrate foil is carried out using two slot dies spaced a certain distance apart. There is a risk that the wet slurry from the first slot die may clog the opening of the second die, making coating the second layer always difficult. Even if the profile thickness changes, it is difficult to control because it is not known whether the problem originates from the first or the second slot die.It is important to independently check the binder distribution in the slurries intended for the two different active material layers shortly before coating. Such a check is currently not possible with the state of the art.

[0008] WO 2022 / 125441 A1 discloses a measuring system and a processing method for continuous pre-lithiation of an anode for a lithium-ion battery. The measuring system integrates at least one complementary non-contact sensor for measuring the surface texture, layer thickness, or roughness in the nanoscale. EP 1 553 406 A1 discloses a double-sided optical inspection system that can detect and classify particles, pits, and scratches on thin-film discs or wafers in a single surface scan.

[0009] The object of the invention is to provide a process arrangement for producing an electrode coating on a carrier foil for an electrode of a battery cell, in which a process adaptation can be carried out depending on the current slurry composition, in particular depending on the solids content, impurities and / or gas inclusions of the slurry.

[0010] The object is solved by the features of claim 1. Preferred developments of the invention are disclosed in the subclaims.

[0011] The invention is based on a process arrangement by means of which an electrode coating can be produced on a carrier foil for an electrode of a battery cell. The process arrangement has a slurry reservoir in which a slurry consisting of powdered solid active material, solvent, binder, and additives is stored. The slurry is a viscose paste that forms the starting component for producing the electrode coating. The process arrangement also has an application tool that is in flow connection with the slurry reservoir. Using the application tool, the slurry is applied to the carrier foil, forming the electrode coating.According to the characterizing part of claim 1, the process arrangement comprises at least one polarimeter with which the slurry composition, in particular its solids content, gas inclusions and / or impurities, can be monitored in an inline process control taking place during the manufacturing process.

[0012] The main idea is to determine the content of dissolved active material inline using the light polarization filter technique and then automatically adjust the process by adding solvent or adding additional slurry or indicate in advance that a certain coating area has a defect.

[0013] The lightwave polarization filter technique is also used to detect gas pockets in the slurry and can then help activate degassing or remove slurry containing gas pockets before it reaches the deposition tool. The lightwave polarization filter can also be used to detect slurry concentration, meaning slurry with higher levels of impurities can be quickly analyzed. This can help highlight coating areas where impurities are higher.

[0014] Light polarization filter technology is a new measurement concept that uses two filters to prevent light waves from escaping. The first filter is fixed in position, and the second filter can be rotated to minimize light leakage. If the solids content is low or high (due to sedimentation), the second filter must be rotated further to prevent light leakage. This is necessary because the difference in solids content can change the polarization direction between the first and second filters. What's new is that the second filter is also fixed (it is calibrated based on the best reference value for solids content). Due to the new solids content, the light will escape from the second filter and fall on the photovoltaic cell, where it ultimately generates a voltage. Based on the generated voltage, the solids content in the slurry can be calculated.This optical polarization filter is placed inside the slitting tool. Based on the voltage signal, an additional entry point for solvent is activated (when the solids content is high due to sedimentation) or an additional entry point for slurry with high solids content (when the solids content is low).

[0015] The presence of gas pockets is detected using the same lightwave polarization filter technology in a transparent slurry feed tube. If a gas bubble is present, the voltage generated by the photovoltaic cell will be different, and this can provide a signal to open the degassing valve or the valve to divert the gas-filled slurry to another tube, which collects the slurry as scrap, or a signal is sent to the system to direct the coating zone containing the gas-filled slurry to scrap.

[0016] The presence of impurities and undissolved particles is also determined in the same way. Many waves are generated here, as each impurity and each undissolved particle generates a wave with a different polarization direction. This means that many waves exit the second filter and fall on the photovoltaic cell. This means that a voltage is generated. Impurities can be measured in the same way using the lightwave polarization filter technique. Here, this light polarization filter is placed in the last filter before the slurry enters the coating.

[0017] For example, the signal from the lightwave polarization technology alerts the maintenance team when the filter needs cleaning. A signal is also sent to the tape machine, which marks the coating zone with heavily contaminated slurry as defective. It is also possible to divert the slurry with high levels of contamination to the scrap material by diverting it through a pilot-operated check valve toward the scrap material tank.

[0018] In lightwave polarization, the light waves are essentially filtered using two filters. Initially, the angle of the second filter is adjusted so that no light passes through. This angle is found for the ideal slurry composition. At this point, the voltage of the photovoltaic cell should be zero. Any deviation in the slurry composition changes the polarization direction and creates light waves that escape the adjustment of the second filter. This creates a voltage in the photovoltaic cell. This voltage difference provides information about the difference in cell chemistry and triggers the necessary reactions to return the slurry composition to the reference value.

[0019] Visible light (such as red, green, or blue light) is normally unpolarized. This means it emits transverse waves in all directions. Assuming a filter (polarizer) is placed near the light source, only light waves whose light transmission direction is parallel to the filter slit will pass through the first filter. All other light waves are filtered out. If a second filter (analyzer) is used, which is rotated 90°, even the light wave that has passed through the first filter is blocked. This means that no light wave can escape from the second filter. It can be assumed that the filter slit in the second filter is smaller than the amplitude of the light wave, and therefore no transverse wave can pass through the second filter.If a photocell is placed after the second filter, it will not display a voltage because no light can pass through two polarizing filters positioned at a 90° angle to each other. Therefore, the two filters are able to block polarized light waves. The light was previously unpolarized, and after passing through the first filter, it is polarized. The second filter blocks this polarized light, preventing light from entering the photovoltaic cell. This is the basic principle of the lightwave polarizing filter.

[0020] It is known that the polarization direction of light changes as it passes through a liquid medium between the first and second filters. This means that the second filter, even though it is at 90° to the first filter, cannot block the polarized light from the first filter. The angle of the second filter must be changed to block the polarized light wave passing through the liquid medium.

[0021] According to the invention, the polarized light from the first filter is first passed through the reference slurry. The reference slurry is stored in a transparent tube within the slotted nozzle. The reference slurry causes the polarization direction of the light wave to change. The second filter is then adjusted so that it can capture all of the light, thus preventing any light wave from reaching the photocell (i.e., photovoltaic receiver) located behind the second filter. If, during the coating process, the solids content of the slurry changes (due to sedimentation) compared to the reference slurry, the polarization direction of the polarized light wave (coming from the first filter) changes from that of the reference slurry. According to the invention, the first filter and the second filter are arranged at a fixed angle of rotation relative to each other. The angle of rotation is calibrated based on the reference slurry.This means that any change in the solid content causes a change in the polarization direction and leads to some light emerging from the second filter. This escaping light ultimately falls on the photovoltaic cell and generates a voltage. The voltage value depends on the difference between the solid content and the reference. The greater the difference in the solid content, the more voltage is generated. This voltage difference signal controls the flow control valve, which can feed either solvent or slurry with a higher solid content into the main slurry, thus bringing the value of the solid content back to the reference value.

[0022] The unpolarized light wave is polarized by the first filter. The second filter, which is at a 90° angle to the first filter, does not allow any light waves to escape. This phenomenon is called polarization of light waves and blocking all light waves using the two-filter technique. All light sources produce unpolarized light waves. For example, red light is shown below as the light source. The filters are represented as two parallel tubes. It can be understood that the distance between the tubes is smaller than the light amplitude, and therefore only the light wave whose transmission direction lies exactly between the two tubes is allowed to pass through, while the other light waves are blocked. This means that the first filter (i.e., polarizer) can polarize light waves. The first filter is called a polarizer. The second filter (i.e., analyzer) is placed so that it has a 90° rotation to the first filter (polarizer).Now, a single polarized light wave that has passed through the first filter is blocked by the second filter (analyzer). In this way, none of the light waves will pass through the second filter. Behind the second filter (analyzer) there is a photovoltaic cell. Since no light wave can pass through the second filter, no light wave falls on the photovoltaic cell and thus no voltage is generated.

[0023] When the polarized light wave passes through a liquid solution or any medium after the first filter (polarizer), the direction of polarization changes. This means that the second filter must be adjusted to a new angle to prevent this altered polarized light wave from passing through it. This means that the analyzer must be adjusted at an angle other than 90° with respect to the polarizer. The polarizer first polarizes the light wave. Now, the reference slurry is held in the transparent tube between the polarizer and the analyzer. The analyzer is then rotated so that no more light escapes through it or the voltage generated across the photovoltaic cell is minimal or equal to zero. Once this light wave polarization filter is calibrated, it can detect any change in the solid content of the slurry by outputting a different voltage.First, the relationship between voltage and slurry concentration must be determined. This allows the output voltage to determine the solids content in the slurry. This voltage signal is fed to the controller, or control unit, which initiates corrective measures to adjust the solids content to the target value. This is the basic idea behind using optical fiber polarization filters to measure and rectify the solids content of slurry.

[0024] A light wave polarization filter can be attached to the slurry inlet into the slot die. The slot die has three chambers. The main slurry flows into the first chamber. The solids content of the slurry is checked using the light wave polarization filter (LWPF). If the solids content is below the setpoint determined by the LWPF, the pilot-operated check valve connected to the second inlet channel, which contains the second slurry with a higher solids content, opens. Once the voltage returns to the reference value, the pilot-operated check valve closes, blocking the inlet of the second slurry. If the solids content is higher than the reference value, the pilot-operated check valve connected to the third inlet channel containing the solvent opens. This dilutes the slurry and returns the solids content to normal.The photovoltaic cell voltage will return to the same voltage as the reference slurry. This will close the pilot-operated check valve connected to the third input channel, thus closing the solvent (or, if applicable, the lower solids slurry) inlet.

[0025] The feed tube has a transparent tube that allows light to pass through. The light passes through the light wave polarizing filter (LWPF) and then generates a voltage across the photocell when a gas entrainment is present. The pilot-operated check valve is opened, allowing the slurry containing gas entrainment to enter the scrap tank. Red light is shown as unpolarized light, which is polarized by the first filter, also called the polarizer. The analyzer is the second filter, which is rotated so that no light enters the photocell. Gas particles change the direction of polarization between the polarizer and the analyzer, allowing some of the light to fall on the photocell, generating a voltage. Based on the voltage, the signal is passed to a pilot-operated check valve, which directs the contaminated slurry (containing gas particles) to the wastewater. Green or blue light can also be used as a light source.

[0026] The key differences of the invention can be summarized as follows: The new lightwave polarization filter (LWPF) technology is used to measure the solids content of the slurry before it is applied to the carrier film. Based on the voltage generated by the light waves emerging from both polarization filters and incident on the solar cell, measures are taken to control the deviation in the solids content. This lightwave polarization filter is mounted inside the slitting tool. The feed line from the slurry reservoir to the application tool is equipped with the same lightwave polarization filter technology to detect gas bubbles during slurry transport. Magnetic and coarse particle filters can be used before the coating process to detect small impurities and undissolved coating particles in the slurry.Slotted nozzles can have multiple inlet chambers and one outlet chamber, allowing slurries with different compositions to be produced in a single layer. Here, too, lightwave polarization technology is used in the inlet and outlet chambers to control the cell chemistry. The new slot design enables the coating of multiple chemical slurries without the need for district layers.

[0027] Normally, defects in the coating system, such as uneven solid content, impurities, or gas bubbles, cannot be easily detected using cameras. This is now possible through the use of lightwave polarizing filters, which are presented here for the first time as a useful tool in the battery production process. It is only necessary to initially calibrate the lightwave polarizing filter so that the ideal slurry composition does not generate any voltage (i.e., no light wave can exist in the second filter). Then, one can intentionally change the ratio of the slurry's solid content and observe how much voltage is generated by the light waves present in the second filter and incident on the photovoltaic cell.Once this information is available, these LWPF sensors can be used to accurately determine the solids content in the slurry, either in the slot die, the filter, or even in the feed pipes. This essentially exploits the phenomenon of the change in the polarization direction of light waves through the flowing medium to calculate the slurry composition.

[0028] Defects detected with this lightwave polarization filter technique can also be used to mark defective coating zones with adhesive tape. This allows coating-related electrode defects to be marked and documented. Otherwise, electrode defects are only marked after the calendering process based on pressing defects. Coating defects are not taken into account. This ensures that the electrode coating is free of defects.

[0029] The advantages of the invention can be summarized as follows: It enables coating with a uniform solids content and mass loading, resulting in higher capacity. The slurry's shelf life can be increased because the problem of sedimentation is solved by inline measurement before coating and subsequent compensation of the slurry's solids content through corrective feeding measures. The slurry contains fewer impurities and undissolved drug particles. Furthermore, a degradation in the performance of the magnetic filter located in the feed line can be predicted much earlier, before more impurities escape from the filter. This increases cell safety and the self-discharge rate. The slurry has fewer gas inclusions, which means fewer holes are formed on the electrode. The electrode is not only free of calendering defects but also free of coating defects.A slot die with multiple inlets and one outlet can be helpful for taking full advantage of varying slurry chemistry along the thickness of the layer. Lightwave polarization filter technology is easily applied in the slot die. Once calibrated, the device consistently delivers reliable results because there are no mechanical parts subject to wear. This lightweight polarization technology can be used in the coating field, but it also works very well in a continuous mixing process based on the extrusion principle. The composition of the output slurry can be automatically adjusted by detecting a voltage deviation and then taking corrective measures, such as adding more active material or solvent. Coating an electrode with two or more layers is possible with a single slot die.No distinct layers are visible in the final coating; only the slurry composition is altered. This increases the cohesion of the coating layers. The new slot design with light polarization filter technology ensures that the binder concentration is maintained as desired along the layer thickness by providing corrective action via a closed-loop control system. Sedimentation is significantly higher with a water-based cathode mixture. The active cathode material and the binder (PVDF) cannot dissolve in water but remain in emulsion form. This light wave polarization filter technology can help control the properties of the slurry. The sedimentation problem will increase as the slurry will have a higher alcohol content in the future to reduce drying time.This lightwave polarization filter technology can help detect the occurrence of sedimentation and take preventive measures, such as circulating the slurry at a higher speed in the storage tank.

[0030] Embodiments of the invention are described below with reference to the attached figures: They show: Fig. 1 to 6 different views illustrating the structure and functioning of the process arrangement according to the invention.

[0031] In the Fig. 1 and Fig. 2 is a process arrangement for the production of an electrode coating 1 ( Fig. 2) on a carrier film 3 for an electrode of a battery cell to the extent necessary for understanding the invention. The process arrangement has a slurry reservoir 5 in which a slurry 7, consisting of a powdered solid active material, solvent, binder and additives, is homogeneously mixed by means of a stirring device 9 and temporarily stored. The slurry 7 is a viscous paste whose solids content is formed by the powdered active material. The viscous paste is the starting component for the electrode coating 1 to be produced. To produce the slurry 7, the powdered solid active material, the solvent, the binder and the additives are mixed in a mixer unit (not shown).

[0032] In the Fig. 1, the slurry reservoir 5 is fluidically connected to an application tool 13 via a supply line 11. The slurry 7 is conveyed by a feed pump (not shown) towards the application tool 13, which is located in the Fig. 2 is shown in an enlarged detail view. Accordingly, the application tool 13 has a total of three application nozzles 15, 17, 19. Of these, a central main application nozzle 17 is fluidically connected to the slurry reservoir 5 via the supply line 11. The slurry 7 is thus applied to the carrier film 3 through the main application nozzle 17. The carrier film 3 is in the Fig. 2 as a continuous web material, which is guided by means of roller guides along a slot-shaped nozzle opening 21 ( Fig. 2) of the application tool 13. The three application nozzles 15, 17, 19 converge at the slot-shaped nozzle opening 21. Above the main application nozzle 17 is a first secondary application nozzle 15, through which an additional slurry 23 with a reduced composition compared to a target composition can be metered. Below the main application nozzle 17 is also a second secondary application nozzle 19, through which a further additional slurry 25 with a higher composition than the target composition can be metered.

[0033] A core of the invention is that a polarimeter 27 is integrated in the main application nozzle 17, which provides an actual value U istwhich correlates with the current process composition, in particular the current process solids content, of the slurry 7 flowing through the main application nozzle 17. The polarimeter 27, together with a control unit 29 and two control valves 31, 33, is part of a control circuit. In the control unit 29, a comparison of the actual value U ist with a reference value U stored in the control unit 29 ref Based on this comparison, the control unit 29 controls the control valves 31, 33 to adjust the metered addition of the respective additional slurry 23, 25. By metering the additional slurry 23, 25, the current solids content of the slurry 7 fed through the main application nozzle 17 can be adjusted toward the target composition before it exits the slot-shaped nozzle opening 21 of the application tool 13.

[0034] Based on the Fig. 3a and Fig. Figure 3b illustrates the structure and operation of the polarimeter 27 integrated into the main application nozzle 17. Accordingly, the polarimeter 27 has a light source 35 with unpolarized light, in whose beam path a polarizer 37 and an analyzer 39 are arranged one behind the other. The polarizer 37 acts as a first polarization filter that transmits light with only one plane of oscillation, i.e., polarized light. A transparent tube section 41 is arranged between the polarizer 37 and the analyzer 39. This tube is positioned fluidically upstream of the main application nozzle 17 and through which the slurry 7 flows in the direction of the nozzle outlet. The analyzer 39 is a second polarization filter that can be rotated with respect to the polarizer 37 in a plane parallel to it. As the polarized light passes through the transparent tube section 41, the oscillation plane of the polarized light rotates by an angle of rotation.Based on the angle of rotation or a value correlating therewith (i.e. a voltage signal U generated by a photovoltaic receiver 43). ist ) the current slurry composition can be determined.

[0035] The reference value U stored in the control unit 29 ref can be according to the Fig. 3b in a reference measurement. In the reference measurement, the transparent tube section 41 of the polarimeter 27 is filled with a reference slurry 8. The oscillation plane of the polarized light rotates by a reference angle of rotation as it passes through the tube section 41. The analyzer 39 is moved to a reference angle of rotation position D ref (especially 90° to the plane of vibration). In the reference angle position D refthe polarized light is completely absorbed by the analyzer 39. A photovoltaic receiver 43 of the polarimeter 27, connected downstream of the analyzer 39 in the beam path, therefore generates a voltage signal U ref as a reference value, which is zero or a minimum value.

[0036] After determining the reference value U ref An inline process measurement can be carried out during the production of the electrode coating 1. During the inline process measurement, the transparent tube section 41 of the polarimeter 27 is flowed through with the process-current slurry 7. Its composition may differ from the reference composition of the reference slurry 8. Accordingly, the oscillation plane of the polarized light rotates as it passes through the tube section 41 by an angle of rotation different from the reference angle of rotation. This allows the polarimeter 27, which is in its reference angle of rotation position D refThe analyzer 39 located there no longer completely absorbs all the polarized light; rather, the analyzer 39 allows a portion 40 ( Fig. 3a) of the polarized light towards the photovoltaic receiver 43. This generates a voltage signal U ist as an actual value that correlates with the current slurry composition. The relationship between the voltage signal U ist and the slurry composition (in the case of Fig. 1 to 3b (especially the solids content) can be determined by preparatory reference measurements.

[0037] If the current slurry solids content is greater than the reference solids content, the control unit 29 controls the upper, first control valve 31, whereby the additional slurry 23 is metered in with a composition reduced compared to the reference composition. This reduces the current process solids content of the slurry 7 to be applied towards the reference solids content. Conversely, the control unit 29 controls the lower control valve 33 to meter the additional slurry 25 with a solids content increased compared to the reference solids content, provided that the slurry 7 has a reduced solids content compared to the reference solids content. This increases the current process solids content towards the reference solids content.

[0038] In the Fig. 4 shows a process arrangement according to a second embodiment. Accordingly, the process arrangement also has a polarimeter 27, which, as can be seen from the Fig. 3a and Fig. 3b. In contrast to the previous embodiment, in the Fig. 4, the polarimeter 27 is not integrated in the application tool 13, but in the supply line 11 leading from the slurry reservoir 5 to the application tool 13. The transparent pipe section 43 of the polarimeter 27 is in this case a component of the supply line 11. With the help of the polarimeter 27, in particular, gas inclusions 45 in the slurry flow can be determined. For this purpose, the polarimeter 27 is again integrated into a control circuit. The control unit 29 of the control circuit is in signal connection with a two-way valve 47, which can be adjusted between a first switching position shown and a second switching position. In the first switching position, the slurry flow is directed towards the application tool 13, while in the second switching position, the slurry flow is directed towards the material waste 49. In the event of an excessively large deviation between a reference composition (i.e., a correlating reference value U ref) and the current slurry composition (i.e. a correlating actual value U ist ), the control unit 29 switches the two-way valve 47 to its second switching position. In this way, the slurry 7 with the excessively large deviation from the reference composition is directed towards the material reject 49. Conversely, if a slurry flow is present that is free of gas inclusions 45, the two-way valve 47 is switched to its first switching position, in which the slurry flow is directed to the application tool 13.

[0039] In the Fig. 5 shows a process arrangement according to a further embodiment, the structure and functioning of which is essentially identical to that of the preceding embodiment of the Fig. 4. In contrast to Fig. 4, a magnetic filter 53 is provided in the area of ​​the supply line 11, with which contaminants 51 in the slurry flow can be removed. Active material contains many contaminants as well as coarse, undissolved particles. These are removed by directing the slurry 7 past the magnetic filter. If the filtering capacity of the magnetic filter 53 decreases, the contaminants 51 are no longer completely removed from the slurry flow. An increased proportion of contaminants 51 in the slurry flow can be detected by the polarizer 27. If this is the case, the control unit controls the two-way valve 47 to its second switching position, so that the contaminated slurry 7 is directed towards the material reject 49.

[0040] In the embodiment of the Fig.6 shows an application tool 13 having a total of three application nozzles 55, 57, 59, which open into a common outlet channel 61 leading to the nozzle outlet 21. Partial slurries of different compositions are coated onto the carrier film 1 via the three application nozzles 55, 57, 59. A polarimeter 27 is integrated into each of the application nozzles 55, 57, 59, which checks the solids content and binder concentration of the respective partial slurry. If, for example, the respective partial slurry has too low a binder content, the flow pressure in the associated application nozzle 55, 57, 59 is increased so that this partial slurry flows more quickly to the outlet channel 61, where all three partial slurries flow together to form a complete slurry, which is applied to the carrier film 3. To ensure that the overall slurry has the desired properties, a polarimeter 27 is also integrated in the area of ​​the outlet channel 61.

[0041] The total slurry 63 is applied as a single layer to the carrier film 3. However, viewed in the thickness direction, this consists of a multi-layer structure with different properties in the thickness direction, since the upper part of the individual layer is chemically closer to the upper incoming partial slurry and the lower part of the individual layer is chemically closer to the lower incoming partial slurry. List of reference symbols 1 Electrode coating 3 Carrier film 5 Slurry reservoir 7 Slurry 8 Reference slurry 9 Stirring device 11 Supply line 13 Application tool 15 Secondary application nozzle 17 Main application nozzle 19 Secondary application nozzle 21 Slot-shaped nozzle opening 23 Additional slurry 25 additional slurry 27 polarimeters 29 Control unit 31, 33 Control valve 35 light source 37 Polarizer 39 Analyzer 40 fraction of polarized light 41 transparent pipe section 43 photovoltaic receivers 45 Gas inclusion 47 Two-way valve 49 Material scrap 51 contaminants 53 filters 55, 57, 59 application nozzles 61 exhaust port D ref Reference rotation position U ref Reference value U ist Actual value QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2022 / 125441 A1

[0008] EP 1 553 406 A1

[0008]

Claims

[1] Process arrangement for producing an electrode coating (1) on a carrier film (3) for an electrode of a battery cell, with a slurry reservoir (5) in which a slurry (7) consisting of powdered active material, solvent, binder and additives is stored, and with an application tool (13) which is in flow connection with the slurry reservoir (5), wherein the slurry (7) can be applied to the carrier film (3) by means of the application tool (13) to form the electrode coating (1), characterized by that the process arrangement has at least one polarimeter (27) with which a slurry composition, in particular the solids content, gas inclusions (45) and / or impurities (51), can be monitored in an inline process measurement carried out during the manufacturing process. [2] Process arrangement according to claim 1, characterized bythat the polarimeter (27) has a light source (35) with unpolarized light, in the beam path of which are arranged in series one behind the other: - a polarizer (37) as a first polarization filter which transmits light with only one plane of oscillation, i.e. polarized light; - an analyzer (39) as a second polarization filter, which is rotatable in particular with respect to the polarizer (37) in a plane parallel thereto; and - a transparent tube section (41) arranged between the polarizer (37) and the analyzer (39), which can be filled with the slurry (7), that the oscillation plane of the polarized light rotates by an angle of rotation when passing through the transparent tube section (41), and that depending on the angle of rotation or a variable correlating therewith (U ist ) the slurry composition can be determined. [3] Process arrangement according to claim 2, characterized bythat for calibrating the polarimeter (27) a reference measurement is carried out, in which the transparent tube section (41) of the polarimeter (27) is filled with a reference slurry (8) having a reference composition, that during the reference measurement the oscillation plane rotates by a reference angle of rotation as the polarized light passes through the tube section (41), and that the analyzer (39) is rotated to a reference angle of rotation position (D ref ) (that is to say, in particular, 90° to the plane of oscillation), in which the analyzer (39) completely absorbs the polarized light, so that a photovoltaic receiver (43) of the polarimeter (27) connected downstream of the analyzer (39) in the beam path generates a voltage signal (U ref ) as a reference value, which is zero or a minimum value. [4] Process arrangement according to claim 3, characterized bythat during the inline process measurement, the transparent tube section (41) of the polarimeter (27) is filled with the process-current slurry (7), the composition of which may differ from the reference composition, so that the oscillation plane of the polarized light rotates by an angle of rotation different from the reference angle of rotation when passing through the tube section (41), whereby the slurry in the reference angle of rotation position (D ref ) no longer completely absorbs the polarized light, but rather allows a portion (40) of the polarized light to pass through to the photovoltaic receiver (43), generating a voltage signal (U ist ) as an actual value that correlates with the current slurry composition in the process. [5] Process arrangement according to claim 4, characterized by that the polarimeter (27) is integrated in a control circuit in which a control unit (29) on the basis of the actual value (Uist ) intervenes in the production process with a corrective measure, in particular in the control unit (29) the actual value (U ist ) with the reference value (U ref ) and that, in particular in the case of a significant deviation between the actual and reference value (U ist , U ref ) the corrective action is initiated. [6] Process arrangement according to one of the preceding claims, characterized by that the application tool (13) has a total of three application nozzles (15, 17, 19), namely - a main application nozzle (17) fluidically connected to the slurry reservoir (5), through which the slurry (7) with a reference composition is to be applied to the carrier film (3); - a first secondary application nozzle (15) through which an additional slurry (23) with a reduced composition compared to the reference composition can be metered; and - a second secondary application nozzle (19) through which an additional slurry (25) with an increased composition compared to the reference composition can be metered. [7] Process arrangement according to claim 6, characterized by that the polarimeter (27) is integrated in the main application nozzle (17), which provides an actual value (U ist ), and in particular that the control unit (29) is based on a comparison between the actual value (U ist ) and a reference value (U ref ) controls the control valves (31, 35), with the aid of which the metering via the first or second secondary application nozzle (15, 19) can be adjusted, whereby the current process composition of the slurry (7) can be adjusted towards the reference composition. [8] Process arrangement according to one of the preceding claims, characterized bythat the polarimeter (27) is integrated in a feed line (11) leading from the slurry reservoir (5) to the application tool (13), and that in particular the transparent pipe section (41) of the polarimeter (27) is a component of the feed line (11), so that the polarimeter (27) can measure an actual value (U ist ) which correlates with the current process composition, in particular impurities (51) and / or gas inclusions (45), of the slurry flow guided through the feed line (11). [9] Process arrangement according to claim 8, characterized by that the control unit (29) is in signal connection with a control valve (47), and that the control valve (47) in a first switching position directs the slurry flow to the application tool (13), and in a second switching position directs the slurry flow in the direction of the material waste (49), and that in particular in the presence of an excessively large deviation between the actual value (U ist ) and a reference value (Uref ) the control unit (29) switches the control valve (47) into its second switching position so that the slurry (7) is directed towards the material reject (49), and that the control unit (29) switches the control valve (47) into its first switching position so that the slurry (7) is directed towards the material reject (49), provided that there is no or only a slight deviation between the actual value (U ist ) and the reference value (U ref ) is present. [10] Process arrangement according to one of the preceding claims, characterized bythat the application tool (13) has several, in particular three, application nozzles (55, 57, 59) which open into a common outlet channel (61) which leads to the nozzle outlet (21), that via the three application nozzles (55, 57, 59) partial slurries of different compositions can be guided into the outlet channel (61), where all three partial slurries flow together to form an overall slurry which is applied to the carrier film (3), and that in particular in each of the application nozzles (55, 57, 59) a polarimeter (27) is integrated which checks the slurry composition, in particular the solids content and binder concentration, of the respective partial slurry, and that in particular if the respective partial slurry has, for example, too low a binder content, the flow pressure in the associated application nozzle (55, 57, 59) is increased so that this partial slurry flows faster to the outlet channel (61),and that in particular in the outlet channel (61) a further polarimeter (27) is integrated to ensure that the overall slurry has the desired properties.,

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