Method for coating a carrier material with an active material to produce an electrode foil for a battery cell

Abstract

The invention relates to a method for coating a carrier material (1) with an active material (2) by means of a Laval nozzle (5) for producing an electrode foil (3) of a battery cell (4), wherein the Laval nozzle (5) has, arranged in succession in the flow direction (6), at least one constricted first section (7), a second section (8) having a minimum flow cross section (9) and an expanded third section (10). The invention also relates to a battery cell.

Description

Technical Field

[0001] This invention relates to a method for coating a carrier material with an active material for manufacturing electrode foils for batteries. The carrier material particularly includes strip-shaped carrier materials. Background Technology

[0002] Batteries, especially lithium-ion batteries, are increasingly used to power motor vehicles. Batteries typically consist of single cells, each with a stack of anode plates, cathode plates, and separators. At least a portion of the anode and cathode plates are designed as current conductors (or dischargers) to conduct the current supplied by the single cell to a load located outside the single cell.

[0003] In the production of lithium-ion battery cells, a carrier material, particularly a strip-shaped carrier material (such as a carrier membrane), is coated with a slurry on both sides using a coating tool. The slurry consists of various components, such as active materials, conductive carbon black, binders, solvents, and other additives if necessary. After coating one side, the coated carrier material is sent to a drying process to evaporate the contained solvents and firmly bond the remaining components to the carrier membrane. The carrier membrane then forms the current conductor of the battery cell.

[0004] The coating produced in this way is porous. Porosity is reduced through calendering, as the coating is compacted during this process. This compaction is essential for increasing a specific capacity (referring to volume) and electrical conductivity.

[0005] The known method of coating the anode and cathode with a slurry, followed by drying and final rolling and cutting, has the following problems:

[0006] • It will generate additional costs and energy requirements for drying solvents (such as NMP-N-Methyl-2-pyrrolidon for the cathode and water for the anode);

[0007] • Compaction must be achieved through calendering, which causes wrinkling and requires complex machinery.

[0008] • It is difficult to produce coatings consisting of different layers with varying densities; therefore, a coating-calendering-coating-calendering cycle must be implemented, and more frequently as needed, thus extending manufacturing time and increasing operating costs.

[0009] • The coating has poor adhesion, so delamination may occur.

[0010] Some suppliers recommend dry coating (solvent-free) as an alternative to wet coating (containing slurry). However, dry coating has the following disadvantages:

[0011] • After dry coating, a heated calendering method is required to melt the binder and distribute it evenly; this increases costs.

[0012] It is also difficult to produce different layers with different densities here;

[0013] • The adhesion of the active material to the carrier material (before calendering) is relatively low.

[0014] Therefore, the known methods have the following drawbacks:

[0015] • The carrier material to be coated must undergo various processes, such as coating and calendering;

[0016] • The carrier material must be rewound after each process step; this results in bending stress and particulate contamination at the electrodes.

[0017] A separate process increases space requirements, cost, and waste;

[0018] • Layer-by-layer coating and compaction in calendering machines are difficult;

[0019] Solvent drying and recovery are energy-intensive and costly processes.

[0020] • The solvent NMP is a hazardous substance and must be handled with care;

[0021] • The viscosity of the slurry plays a decisive role in the quality of the coating; the rheological properties depend on the conductive carbon, binder, and solvent.

[0022] • If degassing is not performed correctly, the wet coating may contain air / gas.

[0023] • The adhesion of the coating to the carrier material depends on the drying area; drying too quickly can lead to cracks and / or reduced adhesion.

[0024] Calendering is associated with problems such as wrinkling caused by uneven stretching between coated and uncoated areas;

[0025] • High compression during the rolling process can lead to lithium plating (or lithium deposition) on the anode;

[0026] Low compression can lead to a loss of cathode conductivity.

[0027] Solutions to problems associated with wet coatings are known. Replacing wet coating with dry coating (solvent-free coating) is primarily done in two different ways:

[0028] Based on the aerosol principle, a dry mixture is sprayed onto the substrate through electrostatic discharge; this creates a porous coating layer; the coating is then calendered at a high temperature (approximately 150°C) to soften and uniformly disperse the binder.

[0029] • The dried mixture is applied to the substrate using a roller / vibrator / sieve and then calendered at a temperature; therefore, no spraying mechanism is required, i.e., coating and calendering are integrated into one operation, or additional rollers can be used to supplement calendering.

[0030] The above solution still has the following problems:

[0031] Strong mixing stress during the dry mixing process can cause conductive carbon black to agglomerate and reduce viscosity;

[0032] • Coatings formed by electrostatic aerosol discharge have low adhesion; this leads to delamination during recoating in the winding process; a calendering process is required for compaction.

[0033] • During the coating and calendering process using rollers, the carrier material wrinkles; in this case, the calendering rollers must be heated, which results in high energy consumption.

[0034] As known from US 2013 / 273407 A1, the active material of the electrode foil has a heat-resistant coating. This coating is applied as a dry coating through a Laval nozzle.

[0035] A method and apparatus for uniform, continuous coating of a carrier material are known from US 8,936,830 B2. The coating material is applied to the carrier material through a Laval nozzle.

[0036] Methods of applying coatings using a supersonic nozzle are known from US 2003 / 0219542 A1 and US 2002 / 0168466 A1.

[0037] An apparatus for producing batteries is known from US 8,142,569 B2. A metal foil is coated with an active material. The coating is applied via a Laval nozzle. Summary of the Invention

[0038] The technical problem to be solved by the present invention is to at least partially solve the problems described with reference to the prior art. In particular, a method for arranging active materials on a carrier material is proposed. The aim is to achieve high efficiency in the manufacturing process while maintaining low cost and high product quality.

[0039] A method for coating a carrier material with an active material using a Laval nozzle helps to solve the aforementioned technical problem.

[0040] This application discloses a method for coating a carrier material with an active material for producing electrode foil for a single battery cell. The coating is performed using a Laval nozzle, wherein the Laval nozzle has a first constricting section, a second section having a minimum flow cross-section (of the Laval nozzle or all three sections), and a third expanding section arranged sequentially along the flow direction. The method includes at least the following steps:

[0041] a) The first airflow is introduced into the Laval nozzle through the first section;

[0042] b) The first particle stream is introduced into the Laval nozzle through the third section, the first particle stream comprising at least an active material or a binder for the active material;

[0043] c) Mix the first airflow and the first particulate stream, and accelerate the first particulate stream by the first airflow flowing at supersonic speed in the third section;

[0044] d) Coating the carrier material with the first particle stream to form a layer of coating.

[0045] The above (non-final) method steps are divided into a) to d) primarily for differentiation, not to enforce order and / or dependency. The frequency of method steps may also vary. Process steps may also overlap at least partially in time. Preferably, steps a) to d) are at least temporarily parallel or synchronous in time. Steps b) to d) are particularly performed after or simultaneously with step a.

[0046] In particular, within the scope of this method, only one Laval nozzle is used, meaning that the airflow and / or particle flow passes through only one Laval nozzle (at least partially). However, for different layers of the coating, Laval nozzles of different designs can be used so that the coating can be produced by different Laval nozzles.

[0047] Laval nozzles are generally known. They typically consist of a converging first section, a second section with a minimum flow cross-section, and a diffusing third section. The Laval nozzle has an inlet upstream of the first section and an outlet downstream of the third section. The Laval nozzle extends along its entire length between the inlet and outlet in the flow direction. The individual sections extend separately for a certain length.

[0048] The principle of a Laval nozzle is based on the different properties of gases flowing at subsonic and supersonic speeds. Due to a constant mass flow rate, the velocity of the subsonic airflow increases as the flow cross-section narrows. The airflow through a Laval nozzle is particularly isentropic (the gas entropy is almost constant). In subsonic flow, sound propagates through the gas. In the second section, the cross-sectional area, or flow cross-section, is at its minimum, and the gas velocity locally becomes sonic (Mach number = 1.0); this state is called choking or "blocked flow." As the flow cross-sectional area of ​​the Laval nozzle increases again in the third section, the gas begins to expand, and the airflow increases to supersonic speeds. A Laval nozzle only produces choking when the pressure and mass flow rate through the nozzle are sufficient to achieve the required rotational speed. Otherwise, supersonic flow is not achieved, and the Laval nozzle behaves similarly to a Venturi tube. When using a Laval nozzle, the inlet pressure in the nozzle must always be significantly higher than the ambient pressure. Furthermore, the gas pressure at the outlet of the third section of the Laval nozzle should not be too low. In practice, the ambient pressure should not exceed approximately twice the supersonic airflow pressure at the outlet so that the supersonic airflow can exit the nozzle.

[0049] In particular, solvent-free coating of the carrier material is recommended. Solvent-free coating using dry particles is an ideal alternative to wet slurry methods because the cost of solvents, as well as the costs of their removal and recycling, are eliminated. With the proposed method, dry powder can be used for coating. That is, no solvent is used. The coating is sprayed onto the carrier material, rather than being applied via electrostatic discharge (using Venturi / aerosol technology).

[0050] Using a Laval nozzle, a supersonic velocity of the gas medium can be achieved at the nozzle's outlet. This means that particles are accelerated to very high speeds, thus applying the carrier material. Due to the high kinetic energy, the dried mixture adheres strongly enough to the carrier material. Furthermore, the coating immediately exhibits high density after coating, thus eliminating the need for calendering for (further) compaction of the active material.

[0051] During calendering, the carrier material for the coating is guided through a roller assembly, which is temperature-controlled if necessary to heat the carrier material. The coating is then compacted by the rollers. Typically, the coating density increases by at least 20%.

[0052] In particular, only a small amount of binder or adhesive material is needed because the high kinetic energy connects the active materials to each other in the coating through solid-state welding.

[0053] The coating can be applied in several layers or with multiple layers applied sequentially. In particular, the last layer applied is heated and leveled according to the known principle of band stretching (leveling). Each layer can have different chemical composition, density, and thickness. Therefore, the desired properties can be adjusted in terms of electrolyte diffusion, conductivity, coating adhesion to the carrier material, and solid-state bonding between particles.

[0054] After coating, the electrode foil produced in this way can undergo a skin drawing process to adjust the final thickness of the electrode foil. During skin drawing, both sides of the coating or the coated carrier material are compressed, while the strip drawing (Nivellieren / ) is performed. Only one side of the coating is treated.

[0055] The final manufacturing step involves breaking the coil before winding. Here, the (uncoated) current collector area, or discharger, is shaped into its final form using a punching process.

[0056] Specifically, prior to step d), i.e., before coating, the carrier material is cut to its final size (width) for the electrode foil. In particular, the width of the carrier material can be coated using a Laval nozzle without relative movement between the carrier material and the Laval nozzle along the width direction. However, if necessary, several Laval nozzles can be used to coat the carrier material together, i.e., using a strip of coating apparatus arranged adjacent to each other along the width.

[0057] The main advantages of the aforementioned method are:

[0058] • No calendering is required after coating because the coating density required for using electrode foil is achieved through high-speed deposition of particles;

[0059] • Dry-mixed powder, i.e., active material and / or binder material, is fed into the third section of the Laval nozzle; this means that at least some of the particles are not heated, but are only accelerated by the airflow escaping from the Laval nozzle.

[0060] • Laval nozzles generate supersonic speeds for particle deposition;

[0061] • For cost reasons, dry air or nitrogen (instead of helium) can be used for the gas flow.

[0062] Here, the Laval nozzle is specifically configured such that the pressure of the airflow in the third section (preferably at the outlet of the Laval nozzle) corresponds to or is slightly lower than the ambient pressure (e.g., at most 20% lower).

[0063] The first airflow moves at a subsonic speed, particularly upon entering the first section. As it converges in the first section up to the lowest flow cross-section, the airflow is accelerated. In the second section, the flow cross-section is smallest, and the gas velocity along the flow direction becomes faster. Downstream from the lowest flow section, in the expanding third section, the flow cross-section becomes increasingly larger. The gas expands, and the airflow velocity increasingly increases into the supersonic range.

[0064] The first gas flow includes at least one of nitrogen, helium, a mixture of nitrogen and helium, or air. The first gas flow may have a high purity relative to the mentioned components. Thus, the first gas flow has at least 95% by volume percentage of, for example, the corresponding components, namely nitrogen, helium, a mixture of nitrogen and helium, or air.

[0065] The airflow at the inlet of the Laval nozzle, i.e., upstream of the first section, has a pressure of 2 to 15 bar, preferably 3 to 12 bar. The first airflow particularly has a temperature not exceeding 120 degrees Celsius, preferably a maximum of 105 degrees Celsius. Particularly preferably, the temperature in the first airflow is at least 80 degrees Celsius, more preferably at least 90 degrees Celsius.

[0066] The pressure of the airflow at the outlet of the Laval nozzle (i.e., downstream of the third section) is 1 to 2 bar. The airflow temperature there is between 40 and 80 degrees Celsius, especially between 50 and 70 degrees Celsius.

[0067] In particular, the volumetric flow rate of the first airflow is 15 to 30 cubic meters per hour.

[0068] At the outlet, the first airflow specifically reaches a Mach number of 1 to 5, preferably 1 to 3.

[0069] The distance between the carrier material and the outlet can be between 5 and 40 mm, especially between 10 and 30 mm.

[0070] The velocity of particles escaping from the outlet is particularly (as an average) between 70% and 90% of the (e.g., first) airflow velocity.

[0071] The particle stream escaping from the Laval nozzle outlet is guided to the carrier material, thereby generating an interaction between the particle stream and the carrier material.

[0072] For particles to be deposited on a carrier material, the particles must move at a critical velocity. The critical velocity depends on the particles being coated. If the particle velocity is below the critical velocity, the particles will be bounced off the carrier material. If the particle velocity is above the critical velocity, the particles will penetrate the substrate and damage it. Particles with a velocity equal to the critical velocity are coated onto the substrate.

[0073] Therefore, high critical velocities are required for the particles. In this method, the particles reach supersonic speeds during the initial gas flow acceleration. The parameters temperature and pressure can be varied to set the particle kinetic energy. The active material is intensely compressed during deposition through a Laval nozzle, thus achieving high density. Subsequent compaction and / or calendering are not required.

[0074] High speeds cannot be achieved in known Venturi tube deposition processes. Gas flow temperature has no effect here; velocity is changed only by pressure. The density of the carrier material is too low, therefore calendering is still necessary.

[0075] In particular, the carrier material is thoroughly cleaned before coating to remove oil, grease, dirt, paint, and other foreign matter. Specifically, the surface of the carrier material is roughened to improve the interaction between the coating and the carrier material and to reduce / remove any inherent oxide layer on the surface. Various methods exist for cleaning surfaces, such as plasma blasting, ultrasonic cleaning, or irradiation.

[0076] The carrier materials used specifically include 10 to 12 μm thick copper for the anode and 12 to 15 μm thick aluminum for the cathode.

[0077] After cleaning, the carrier material is first cut into smaller widths, particularly by mechanical segmentation, laser, waterjet, or ultrasonic cutting. Segmentation is especially important before coating, so that deposition can be performed on the final desired width of the carrier material. If the segmentation or cutting of the carrier material or coating carrier material is performed after coating, a lower-density powder layer can adhere to the cutting edge and the cutting margin.

[0078] In particular, Laval nozzles can be used to produce different coatings with different densities.

[0079] In particular, the material to be applied to the coating is powder and solvent-free.

[0080] In particular, the material of the first particle stream is in powder form and solvent-free.

[0081] Specifically, it includes at least one of conductive carbon black, NMC (lithium nickel cobalt manganese as lithium storage active material), graphite (as lithium storage active material), CNT (carbon nanotubes), SBR (styrene-butadiene rubber as binder), CMC (carboxymethyl cellulose polymer), PVDF (polyvinylidene fluoride), and porous graphite. Components among these materials that are not binders are hereinafter considered active materials.

[0082] The coating materials to be applied include, for example, 2% conductive carbon black, 0.5% CNT, 2% porous graphite, PVDF and NMC for cathodes.

[0083] The coating materials to be applied include, for example, 2% conductive carbon black, 0.5% CNT, 2% porous graphite, 3 to 4% SBR, 1 to 2% CMC, and the remainder (non-porous) graphite for the anode.

[0084] Particle size, especially the median of particles in at least one particle stream, is particularly between 5 and 100 μm (diameter).

[0085] As the first particle stream enters the third section, for example, a higher temperature can be set for the first gas flow so that the gas flow rate can be adjusted. This can prevent at least partial melting of the first particle stream or the binding material, or prevent unwanted particle agglomeration of the first particle stream, such as conductive carbon black.

[0086] Particle aggregation is detrimental to the flowability of the particle stream and, for example, affects the achievable density of the coating.

[0087] In addition, it can prevent the Laval nozzle from clogging in the second section, since at least a portion of the coating material to be applied is fed downstream of the second section.

[0088] Furthermore, compared to the highly turbulent flow conditions of the second section, the third section exhibits laminar flow conditions. This results in reduced friction in the material used for coating, and the material can be accelerated to higher velocities.

[0089] In particular, the first particle stream mixes with the second airflow before being introduced into the third section. Specifically, the second airflow branches off from the first airflow. However, separate airflows can also be generated. Through the second airflow, the first particle stream can be better introduced into the third section and distributed there.

[0090] The explanation of the first airflow can be applied to the second (or third) airflow, and vice versa.

[0091] Specifically, the first particle flow is introduced into the third section through multiple inlet openings. In particular, at least two, preferably at least three, and more preferably at least four inlet openings are provided.

[0092] In particular, at least two inlet openings are at different distances from the minimum flow cross-section. Specifically, the difference in distance is at least 3 to 15 mm, preferably 3 to 8 mm.

[0093] In particular, at least two inlet openings are offset from each other along the transverse flow direction. In particular, the inlet openings are uniformly distributed along the circumferential direction.

[0094] Turbulence can be prevented by using multiple inlet openings and, if necessary, special arrangements.

[0095] Specifically, the active material (particularly without binder) is introduced into the Laval nozzle as a second particulate stream through the first section, and the binder material (with or without active material) is introduced into the Laval nozzle as a first particulate stream through the third section. Each particulate stream may be mixed with the second (or third) gas flow before being introduced into the respective section, particularly before the respective section.

[0096] By using the input through the third section, the melting of the binder particles can be prevented.

[0097] As the active material is fed through the first section, it can be heated by the temperature of the first gas flow located there, thereby softening the particles in the second particle flow. However, this will not exceed the melting temperature of the active material.

[0098] Specifically, the third airflow is introduced into the Laval nozzle through the third section. Specifically, the third airflow is introduced into the third section through its own inlet opening. Specifically, the third airflow is supplied separately (i.e., not as particulate flow supplied through the same inlet opening) to the third section.

[0099] In particular, the third airflow is used to further mix the cementing material entering the third section with the second particulate flow entering through the first section. Specifically, the third airflow is designed to generate additional turbulence in the third section, thereby causing better mixing of the particulate flow.

[0100] In particular, the supply of particulate flow and / or gas flow into the Laval nozzle can be controlled by an adjustable valve.

[0101] Specifically, steps a) to d) are performed sequentially multiple times on the carrier material to apply the active material to multiple layers. In particular, between the processes of each step a) to d), i.e., especially after each layer of coating is applied, the surface of the coating is subjected to heat treatment (cooling or heating) of the coated carrier material and / or strip drawing of the coating surface.

[0102] In particular, after any coating of the carrier material, a cooling process occurs first, through which the coating is cooled.

[0103] Specifically, the carrier material to be coated is directly heated before stretching or stretching, particularly to a temperature between 100 and 140 degrees Celsius, preferably between 110 and 130 degrees Celsius.

[0104] Specifically, the first (first applied) layer of the coating has a first thickness, and the second layer applied after the first layer has a second thickness greater than the first thickness. For example, the first thickness is between 5 and 20 μm, and the second thickness is between 20 and 40 μm. The thickness of other layers can be between 20 and 60 μm. In particular, the third layer is thicker than the second layer.

[0105] Specifically, the first (first applied) layer of the coating has a first thickness, and the second layer applied after the first layer has a second thickness, which is less than the first thickness. Other layers may each have other thicknesses. In particular, the third layer has a thickness less than the second layer. The thickness of each layer can be adjusted, especially by regulating the pressure of at least one airflow (particularly the first airflow).

[0106] In particular, each layer may have at least one of its own, if necessary, different configurations regarding at least one of the following parameters: density, thickness, composition.

[0107] In particular, after step d), the thickness of at least one coating layer is further increased by a maximum of 10%, preferably by a maximum of 5%, and more preferably by a maximum of 2%.

[0108] Laval nozzles are characterized by a first section that converges upstream in the flow direction and a third section that expands downstream. The properties of the Laval nozzle are determined by the profile and length of the expanding third section and the ratio of the outlet section to the minimum flow cross-section (expansion ratio). The minimum flow cross-section is located in or forms the second section. The Laval nozzles used here can be tapered (constant expansion angle) or bell-shaped (expansion angle that decreases along the length of the third section) in the third section.

[0109] The bell-shaped profile of the third section particularly allows for better application behavior of the applied particles. Therefore, it is especially advantageous if the entire third section is bell-shaped. However, only a portion of the third section can be bell-shaped, while the remainder can differ, for example, being designed as a cone or cylinder. The beginning of the third section, i.e., the connection with the second section, is preferably bell-shaped. The bell shape should extend at least 30% or at least 50% of the length of the third section along the flow direction. Afterward, the remainder of the third section may transition to another form. Abrupt transitions from bell-shaped to conical or cylindrical shapes should be particularly avoided. Abrupt transitions can disrupt the uniformity (laminar) of the airflow or particle flow.

[0110] The length of the third section extends along the flow direction between the minimum flow cross section, or the beginning of the expansion section, and the outlet of the Laval nozzle.

[0111] The bell-shaped expansion of the third section produces a particularly pronounced laminar flow in the airflow or particle flow. Therefore, the highest particle velocities can be achieved in the particle flow because friction is minimized.

[0112] Favorable coating effects can be achieved using Laval nozzles with an expansion ratio (outlet diameter / minimum flow cross-section diameter) between 1 and 25. This is particularly advantageous if the Mach number of the airflow and / or particles at the outlet is between 1 and 5, depending on the particle size. For thicker coatings, smaller particles require higher Mach numbers.

[0113] In particular, the third section of the Laval nozzle may have one of the following shapes:

[0114] • Conical shape;

[0115] • The conical shape transitions into a cylindrical shape in the flow direction; the transitions occur at 30% and 50% of the length of the third section, respectively.

[0116] Bell-shaped;

[0117] • Bell-shaped, wherein the bell shape transitions to a cube or pyramid shape; the transition occurs after 30% or 50% of the length of the third segment.

[0118] In particular, the diameter of the Laval nozzle inlet is between 5 and 30 mm, especially 10 to 20 mm. In particular, the diameter of the Laval nozzle outlet is between 15 and 60 mm, especially 20 to 50 mm. In particular, the diameter of the minimum flow cross-section is between 2 and 5 mm. In particular, the length of the first section along the flow direction is between 10 and 25 mm, especially between 10 and 20 mm. In particular, the length of the third section along the flow direction is between 25 and 40 mm, especially between 30 and 35 mm.

[0119] The shape of the Laval nozzle can be specifically selected based on the desired thickness or uniformity of thickness. Preferably, a bell shape followed by a square third section is used, as this achieves a uniform coating thickness.

[0120] In addition, a single battery cell is proposed, comprising at least a housing and at least one electrode foil disposed therein, the electrode foil being coated with at least an active material by the method described.

[0121] The battery cell includes, in particular, a housing that surrounds a certain volume and at least one electrode foil of a first electrode type disposed in the volume, a second electrode foil of a second electrode type, a separator material disposed between the two electrode foils, and a liquid electrolyte.

[0122] Single-cell batteries are specifically pouch cells (with a deformable casing made of foil pouches) or cylindrical cells (with a rigid casing). A pouch is a known deformable casing component used as the casing for so-called pouch batteries. It is a composite material, including, for example, plastics and aluminum.

[0123] Single-cell batteries, especially lithium-ion single-cell batteries.

[0124] Multiple electrode foils are arranged individually in a stack, and in particular, form a stack. The electrode foils are assigned to different electrode types, i.e., they are designed as anodes or cathodes. The anodes and cathodes are arranged separately from each other by a diaphragm material.

[0125] A battery cell is an electrical storage device, for example, used to store electrical energy in a motor vehicle. Specifically, the motor vehicle has an electric motor (traction drive) that drives the vehicle, and the motor is powered by the electrical energy stored in the battery cell.

[0126] A motor vehicle is also proposed, comprising at least a traction drive and a battery with at least one of the battery cells, wherein the traction drive is powered by at least one battery cell.

[0127] This method is implemented, in particular, by means of a controller equipped, configured, or programmed to implement the method. At least the following can be performed with the aid of a controller:

[0128] • The carrier material is fed relative to at least one Laval nozzle;

[0129] • Adjust at least one airflow;

[0130] • Adjust at least one particle flow;

[0131] Adjust the above parameters, such as pressure, temperature, and volumetric flow rate.

[0132] In particular, a coating apparatus is proposed that is particularly suitable for carrying out the above-described method.

[0133] The coating apparatus specifically includes the aforementioned control unit.

[0134] In addition, the method can also be executed by a computer or using the processor of a control unit.

[0135] Therefore, a data processing system is also proposed, which includes a processor adapted / configured to perform partial steps of the proposed or suggested method.

[0136] A computer-readable storage medium is provided herein, comprising instructions that, when executed by a computer / processor, cause it to perform at least some steps of the method or the suggested method.

[0137] The implementation of this method can be specifically transferred to a single battery cell, a motor vehicle, a coating device, a control unit, and a method that can be transferred to a computer (i.e., a computer or processor, a data processing system, a computer-readable storage medium), and vice versa.

[0138] The use of indefinite articles ("a", "a", "a" and "a"), particularly in the claims and descriptions that repeat them, should be understood as such, rather than as a numeral. Therefore, terms or components introduced with them should be understood in such a way that they appear at least once, but in particular, they may appear multiple times.

[0139] It should be noted beforehand that the numerals used herein ("first," "second," ...) are primarily (only) used to distinguish several similar objects, sizes, or processes; that is, they do not necessarily specify any dependency and / or order among these objects, sizes, or processes. If dependency and / or sequence are required, they will be explicitly stated here, or will be obvious to a person skilled in the art when studying the specifically described design. A description of one of these components may apply equally to all or part of multiple such components, provided that a component can appear multiple times ("at least one"), but this is not mandatory. Attached Figure Description

[0140] The invention and its technical content are explained in more detail below with reference to the accompanying drawings. It should be noted that the invention is not limited to the illustrated embodiments. In particular, unless explicitly stated otherwise, certain aspects of the facts explained in the drawings can be extracted and combined with other components and knowledge in this specification. It should be particularly noted that the drawings shown, and especially the scale shown, are merely schematic. In the drawings:

[0141] Figure 1 A coating apparatus for performing the method according to the first embodiment is shown;

[0142] Figure 2 A portion of a coating apparatus for performing the method according to the second embodiment is shown;

[0143] Figure 3 A coating apparatus for performing the method according to the third embodiment is shown;

[0144] Figure 4 A coating apparatus for performing the method according to the fourth embodiment is shown;

[0145] Figure 5 A perspective view showing a first embodiment of the Laval nozzle;

[0146] Figure 6 A perspective view showing a second embodiment of the Laval nozzle;

[0147] Figure 7 A perspective view showing a third embodiment of the Laval nozzle;

[0148] Figure 8 A perspective view showing a fourth embodiment of the Laval nozzle; and

[0149] Figure 9 A single battery cell is shown. Detailed Implementation

[0150] Figure 1A coating apparatus 31 for implementing the method according to the first embodiment is shown. The coating apparatus 31 includes a Laval nozzle 5 having a constricted first section 7, a second section 8 having a minimum flow cross-section 9, and an expanding third section 10 arranged sequentially along a flow direction 6. The Laval nozzle 5 has an inlet 32 ​​upstream of the first section 7 and an outlet 33 downstream of the third section 10. The Laval nozzle 5 extends along the flow direction 6 over its entire length between the inlet 32 ​​and the outlet 33. The individual sections 7, 8, and 10 each extend over a length 25.

[0151] According to step a) of the method, the first airflow 11 is introduced into the first section 7 of the Laval nozzle 5 through the inlet 32. The first airflow 11 is controlled by the valve 30. The first airflow 11 is compressed to a predetermined pressure by the compressor 27 and heated to a predetermined temperature by the heating device 28.

[0152] According to step b), a first particle stream 12 is introduced through the third section 10 of the Laval nozzle 5, which includes at least the active material 2 and the binder material 13 for the active material 2. The active material 2 and the binder material 13 are mixed in the mixing device 29 and introduced into the third section 10 as a common first particle stream 12 through the inlet opening 17.

[0153] As the first particle stream 12 is supplied to the third section 10, a higher temperature can be set for the first airflow 11 so that the speed of the airflow 11 can be adjusted. At least partial melting of particles of the first particle stream 12, such as the binder material 13, or unwanted particle agglomeration of the active material 2, such as conductive carbon black, can thus be prevented.

[0154] Furthermore, clogging of the Laval nozzle 5 in the second section 8 can be prevented because the material of the coating 15 to be applied is fed downstream of the second section 8.

[0155] Furthermore, compared to the relatively turbulent flow conditions in the second section 8, the third section 10 further establishes laminar flow conditions. This results in reduced friction in the material used for the coating 15, and the material can be accelerated to higher speeds.

[0156] The first particle stream 12 is mixed with the second airflow 16 before being introduced into the third section 10. The second airflow 16 branches off from the first airflow 11. Due to the second airflow 16, the first particle stream 12 can be better introduced into the third section 10 and dispersed there.

[0157] According to step c), the first airflow 11 and the first particulate stream 12 are mixed in the third section 10 and the first particulate stream 12 is accelerated by the first airflow flowing at supersonic speed in the third section 10.

[0158] According to step d), the first particle stream 12 is applied to the carrier material 1 to form layers 14, 23 of the coating 15. The distance 18 between the carrier material 1 and the outlet 33 can be between 5 and 40 mm.

[0159] Figure 2 A portion of a coating apparatus for performing the method according to the second embodiment is shown. A description of the first embodiment is cited.

[0160] Unlike the first embodiment, the first particle flow 11 is introduced into the third section 10 through multiple inlet openings 17. Four inlets 17 are provided here.

[0161] The distances between the inlet opening 17 and the minimum flow section 9 are different.

[0162] Furthermore, the inlet openings 17 are offset from each other along a circumferential direction 19 transverse to the flow direction 6. The inlet openings 17 are evenly distributed along the circumferential direction 19 and offset from each other by 90 degrees.

[0163] Turbulence in the third section 10 can be prevented by the multiple inlet openings 17 and their special arrangement.

[0164] Figure 3 A coating apparatus 31 for performing the method according to the third embodiment is shown. A description of the first embodiment is cited.

[0165] Unlike the first embodiment, the active material 2 (unbound material 13) is introduced into the Laval nozzle 5 as a second particle stream 20 through the first section 7, and the binder material 13 is introduced into the Laval nozzle 5 as a first particle stream 12 through the third section 10. Each particle stream 12, 20 is mixed with the second gas stream 16 and then introduced into the corresponding sections 7, 10. A respective mixing device 29 is provided for the active material 2 and for the binder material 13.

[0166] The cementing material 13 is input through the third section 10, which prevents the cementing agent particles from melting.

[0167] As the active material 2 is input through the first section 7, it can be heated by the temperature of the first gas flow 11 located there, thus softening the particles of the second particle flow 20. However, the melting temperature of the active material 2 is not exceeded.

[0168] The input of airflows 11 and 16 and particulate flows 12 and 20 is controlled by valve 30.

[0169] Figure 4 A coating apparatus for performing the method according to the fourth embodiment is shown. A description of the third embodiment is cited.

[0170] Unlike the third embodiment, the third airflow 21 is introduced into the Laval nozzle 5 through the third section 10. The third airflow 21 is introduced into the third section 10 through a separate inlet opening 17. The third airflow 21 is supplied separately (i.e., without the particle flow 12, 20 input through the same inlet opening 17) to the third section 10.

[0171] The third airflow 21 is used to further mix the cementing material 13 input to the third section 10 with the second particulate stream 20 supplied via the first section 7. In particular, the third airflow 21 is designed to generate additional turbulence in the third section 10, thereby causing better mixing of the particulate streams 12, 20.

[0172] The input of each particle stream 12, 20 and each airflow 11, 16, 21 to the Laval nozzle 5 is controlled by an adjustable valve 30.

[0173] Figure 5 A perspective view of a first embodiment of the Laval nozzle 5 is shown. The Laval nozzle 5 has a constricted first section 7, a second section 8 having a minimum flow cross-section 9, and an expanding third section 10 arranged sequentially along the flow direction 6. The Laval nozzle 5 has an inlet 32 ​​upstream of the first section 7 and an outlet 33 downstream of the third section 10. The Laval nozzle 5 extends along the entire length of the flow direction 6 between the inlet 32 ​​and the outlet 33. Each individual section 7, 8, and 10 extends for a length of 25.

[0174] The performance of the Laval nozzle 5 is determined by the profile and length 25 of the expanded third section 10, as well as the ratio (expansion ratio) of the outlet cross section to the minimum flow cross section 9. The minimum flow cross section 9 is arranged in or forms the second section 8.

[0175] The current Laval nozzle 5 is implemented in a conical shape (constant expansion angle) in the third section 10.

[0176] Figure 6 A perspective view of a second embodiment of the Laval nozzle 5 is shown. Figure 5 The description was cited.

[0177] Unlike the first embodiment, the Laval nozzle 5 has a conical (conical) shape that transitions to a cylindrical shape in the flow direction 6; wherein the transition occurs after approximately 50% of the length 25 of the third segment 10.

[0178] Figure 7 A perspective view of a third embodiment of the Laval nozzle 5 is shown. Figure 5 The description was cited.

[0179] Unlike the first embodiment, this Laval nozzle 5 has a bell-shaped profile in the third segment 10.

[0180] Figure 8 A perspective view of a fourth embodiment of the Laval nozzle 5 is shown. Figure 7 The description was cited.

[0181] Unlike the third embodiment, only a portion of the third section 10 of the Laval nozzle 5 is bell-shaped, while the rest of the third section 10 is pyramid-shaped or the bell-shaped horizontal portion gradually transitions to a square cross-section at the outlet 33.

[0182] The bell-shaped diffusion shape of the third section 10 produces a particularly pronounced laminar flow of airflows 11, 16, 21 or particle flows 12, 20. As a result, the maximum velocity of the particles in particle flows 12, 20 can be achieved because friction is reduced to a minimum.

[0183] Figure 9 A single battery cell 4 is shown, comprising at least a housing 26 and at least one electrode foil 3 disposed therein, which is coated at least with an active material 2 by the method described. The electrode foil 3 comprises a carrier material 1 with coatings 15 on both sides.

[0184] The first (pre-applied) layer 14 of coating 15 has a first thickness 22, and the second layer 23 following the first layer 14 and applied on the first layer 14 has a second thickness 24, wherein the second thickness 24 is greater than the first thickness 22. These descriptions apply to each coating applied to different sides of the carrier material 15.

[0185] List of reference numerals

[0186] 1. Carrier material

[0187] 2. Active materials

[0188] 3. Electrode foil

[0189] 4 single-cell battery

[0190] 5. Laval nozzle

[0191] 6. Circulation Direction

[0192] 7. First Section

[0193] 8. Second Part

[0194] 9. Flow cross-section

[0195] 10. Third Section

[0196] 11 First airflow

[0197] 12 First Particle Flow

[0198] 13. Adhesive materials

[0199] 14 First Layer

[0200] 15 Coatings

[0201] 16 Second airflow

[0202] 17. Entrance opening

[0203] 18 Distance

[0204] 19. Circumferential direction

[0205] 20 Second Particle Flow

[0206] 21 Third airflow

[0207] 22 First Thickness

[0208] 23 Second Floor

[0209] 24 Second Thickness

[0210] 25 Length

[0211] 26. Shell

[0212] 27 Compressor

[0213] 28 Heating device

[0214] 29. Mixing equipment

[0215] 30 valve

[0216] 31 Coating Equipment

[0217] 32 entrances

[0218] 33 Exports

Claims

1. A method for coating a carrier material (1) with an active material (2) using a Laval nozzle (5) for use in manufacturing an electrode foil (3) for a single battery cell (4), characterized in that, The Laval nozzle (5) has at least one constricting first section (7), a second section (8) having a minimum flow cross-section (9), and an expanding third section (10) arranged sequentially along the flow direction (6); wherein the method comprises at least the following steps: a) The first airflow (11) is introduced into the Laval nozzle (5) through the first section (7); b) The first particle stream (12) is introduced into the Laval nozzle (5) through the third section (10), the first particle stream (12) comprising at least a binder material (13) for the active material (2); c) Mix the first airflow (11) and the first particulate stream (12), and accelerate the first particulate stream (12) by the first airflow (11) flowing at supersonic speed in the third section (10); d) Coat the carrier material (1) with the first particle stream (12) to form layers (14, 23) of the coating (15). The active material (2) is introduced into the Laval nozzle (5) as a second particle stream (20) through the first section (7), and the cementing material (13) is introduced into the Laval nozzle (5) as the first particle stream (12) through the third section (10). The active material input through the first section is heated to a temperature not exceeding the melting temperature of the active material by the temperature of the first gas flow, thereby being softened.

2. The method according to claim 1, characterized in that, The first gas flow (11) includes at least one of nitrogen, helium, a mixture of nitrogen and helium, or air.

3. The method according to claim 1, characterized in that, The material of the first particle stream (12) is powder and solvent-free, and includes at least one of conductive carbon black, NMC, graphite, CNT, SBR, CMC, PVDF and porous graphite.

4. The method according to claim 1, characterized in that, The first particle stream (12) is mixed with the second airflow (16) before being introduced into the third section (10).

5. The method according to claim 1, characterized in that, The first particle stream (12) is introduced into the third section (10) through multiple inlet openings (17).

6. The method according to claim 5, characterized in that, At least two inlet openings (17) are arranged at different distances (18) from the minimum flow cross section (9).

7. The method according to claim 5 or 6, characterized in that, At least two inlet openings (17) are arranged offset from each other in a circumferential direction (19) that extends laterally to the flow direction (6).

8. The method according to claim 1, characterized in that, The third airflow (21) is introduced into the Laval nozzle (5) through the third section (10).

9. The method according to claim 1, characterized in that, Steps a) to d) for the carrier material (1) are performed sequentially multiple times, thereby applying the active material (2) to multiple layers (14, 23).

10. The method according to claim 9, characterized in that, The first layer (14) of the coating (15) has a first thickness (22), and the second layer (23) applied after the first layer (14) has a second thickness (24), wherein the second thickness (24) is greater than the first thickness (22).

11. The method according to claim 9 or 10, characterized in that, The first layer (14) of the coating (15) has a first density, and the second layer (23) applied after the first layer (14) has a second density, wherein the second density is less than the first density.

12. The method according to claim 1, characterized in that, The density of layers (14, 23) after step d) increases by up to 10%.

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