Apparatus for coating a sheet-shaped carrier material with a slurry

Abstract

The present invention relates to an apparatus for coating a sheet-like carrier material (1) with a conductive or ceramic slurry (3), the apparatus having a continuously rotating microgravure roll (2) designed to transfer the conductive or ceramic slurry on the circumference (21) of the microgravure roll to the sheet-like carrier material transported in a feed direction (11). According to the invention, the apparatus has a pressure chamber doctor blade (4) designed to transfer the conductive or ceramic slurry onto the circumference of the microgravure roll under positive pressure. The present invention also relates to an assembly for producing a separator film.

Description

[Technical Field]

[0001] The present invention relates to the technical field of manufacturing separator films and electrode diverters, and in particular to an apparatus for manufacturing separator films and electrode diverters for lithium ion batteries. [Background technology]

[0002] Separator films are used to spatially separate electrodes within a battery. To this end, they must act as a barrier to electronic conduction to prevent short circuits between the electrodes. Furthermore, they must allow ion transport between the electrodes. For these reasons, separator films are often made from ceramic materials, and their advantageous properties can be achieved by tailoring their porosity during manufacturing.

[0003] To increase the gravimetric energy density of the battery, the separator must be as thin and light as possible. However, to prevent the battery from catching fire or experiencing thermal runaway, the mechanical strength of the film must be ensured. This places particularly high demands on the achievable tolerances of the manufacturing process and manufacturing equipment.

[0004] Typically, a sheet-like carrier material is coated with a conductive or ceramic slurry. The ceramic slurry is a suspension of ceramic raw material particles in a solvent, usually deionized water. The ceramic slurry layer is finally transferred to a dryer, where the solvent evaporates. The above-mentioned important properties of the separator film are already decisively influenced during the coating of the sheet-like carrier material.

[0005] The conductive slurry can be a carbon-containing slurry, such as a conductive carbon slurry and / or graphite slurry and / or activated carbon slurry for electrode diverters. Like ceramic slurries for coating separator films, conductive adhesion promoters for battery applications also tend to settle and foam during application to the current collector. In particular, carbon black, the main ingredient in the formulation, tends to form chain-like aggregates. These carbon black aggregates have a good affinity with air, further stabilizing the microcellular foam that forms. Common coating defects include "pinholes," which are micro-bubbles that burst after application to the current collector, and uneven, streaky, opaque coatings caused by the precipitation of components in the coating mass within the application unit due to settling / separation. These defects result in uneven transfer to the current collector.

[0006] Conventional coating devices for coating with coating liquids, such as inks or adhesives, have a continuously rotating microgravure roll designed to transfer the coating liquid on the circumference of the microgravure roll to a sheet-like carrier material transported in the feed direction. Such devices are described in the document EP 0 214 574 A1. To transfer the coating liquid to the circumference of the microgravure roll, corresponding devices have a flash chamber and a doctor blade, which forms a coating gap on the circumference of the microgravure roll along the length of the microgravure roll. The coating liquid is supplied directly to the coating gap via the flash chamber and transferred to the circumference. Similar devices are also described in documents DE 100 61 710 A1, DE 197 54 684 A1, DE 199 26 956 A1, DE 299 17 981 U1, DE 20 2006 003 265 U1, EP 2 632 605 B1 or WO 2020 / 025349 A1.

[0007] The problem here is that conductive or ceramic slurries differ from conventional coating liquids. Specifically, slurries are multiphase fluids with solid particles and are prone to settling. The conductive or ceramic particles tend to form deposits on the walls of the device, particularly in the flash chamber and on the doctor blade. As the device operates for an extended period of time, the flow field within the device and the effective width of the coating gap change. To ensure precise manufacturing tolerances, operation must be interrupted periodically to thoroughly clean the device of deposits.

[0008] A further problem arises from the inflow of ambient air into the conductive or ceramic slurry, which essentially occurs in the flash chamber. In devices known in the prior art, this inflow leads to coating defects, such as insufficient wetting of the film due to microscopic air bubbles. When the microscopic air bubbles in the conductive or ceramic slurry are transferred onto the web using a gravure roll, the air bubbles displace the coating mass, forming defects there. This means that there is no or very little conductive or ceramic slurry in these areas. These defects reduce the protective effect of the conductive or ceramic layer.

[0009] Furthermore, ceramic slurries differ from conventional coating materials in terms of rheology. Therefore, even at moderate gravure roll rotation speeds or low web feed rates, ceramic slurries tend to bounce back. The bounce back on the web causes coating defects. Furthermore, structural measures in coating plants must protect the surrounding area from heavy contamination.

[0010] Conventionally used gravure rolls with diameters of 250 mm to 400 mm have a radius of curvature that is too large. The wider the coating line formed between the gravure roll and the carrier material, the more separation processes occur between the ceramic solids and the solvent of the ceramic slurry in the area of ​​the transfer point to the web. This results in undesirable streaky coating. Summary of the Invention

[0011] It is therefore an object of the present invention to further develop the initially mentioned device so that it is suitable for coating a sheet-like carrier material with an electrically conductive or ceramic slurry. A corresponding device is described by claim 1. Advantageous embodiments are the subject matter of claims 2 to 14. Claim 15 describes an assembly for producing an electrically conductive or ceramic separator film or electrode diverter, which comprises a corresponding device.

[0012] Thus, an apparatus is provided comprising a pressure chamber doctor blade designed to transfer a conductive or ceramic slurry to the circumference of a microgravure roll.

[0013] When coating a sheet-like carrier material with a conductive or ceramic slurry, the microgravure roll is characterized by a relatively small diameter. The small diameter and the resulting small radius of curvature prevent unwanted separation processes. The microgravure roll can have a diameter of 60 mm to 150 mm.

[0014] However, the small diameter of the microgravure roll in typical equipment often has a negative impact on the maximum achievable speed of the carrier material. In particular, when the carrier material speed is high, and thus the rotation speed of the microgravure roll is significantly higher than that of a conventional gravure roll, low-viscosity conductive or ceramic slurries tend to separate from the gravure roll due to centrifugal force and splash or atomize. On the other hand, the pressure chamber doctor blade counteracts this effect, allowing for higher carrier material speeds. Carrier material speeds can be up to 500 m / min.

[0015] The feed and rotation directions of the microgravure roll may be opposite.

[0016] Furthermore, the pressure chamber doctor blade may have a pressure chamber adjacent to the first circumferential portion of the microgravure roll and isolated from the environment of the apparatus. In the pressure chamber, an overpressure at the inlet side of the pressure chamber forms a liquid barrier between the adjacent pressure chamber doctor blade and the microgravure roll, thereby minimizing air infiltration into the pressure chamber. The conductive or ceramic slurry in the pressure chamber is maintained substantially free of microbubbles. The overpressure in the pressure chamber may be 50 to 800 mbar, particularly 100 to 500 mbar.

[0017] A further benefit of the overpressure in the pressurized chamber results from faster filling of the cups and / or engraved lines of the microgravure roll. Because only a small amount of conductive or ceramic slurry is applied, the scoop volume of the microgravure roll is small and therefore the structure of the microgravure roll is very fine. The device is suitable for a 10 g / m 2 Less than 5g / m 2 The carrier material may be designed to be coated with a conductive or ceramic slurry having a surface density of less than 1000 .mu.m.

[0018] This type of equipment often encounters problems filling the cups and / or engraved lines of the microgravure roll, especially at high coating speeds. Here, overpressure in the pressurized chamber facilitates accelerated filling of the cups and / or engraved lines, thereby enabling these coating speeds. Furthermore, they can easily be "overdosed" on the outflow doctor blade. A positive pressure gradient between the pressurized chamber and ambient pressure forces additional coating fluid downstream below the doctor blade, overfilling the gravure roll in a controlled manner, which has a positive effect on fluid transfer to the web and thus coating quality.

[0019] The pressure chamber doctor blades may have a delivery doctor blade and a receiving doctor blade that seal the pressure chamber from the environment in the direction of rotation of the microgravure roll or against the direction of rotation of the microgravure roll.

[0020] The pressure chamber may have a feed line designed to supply the conductive or ceramic slurry into the pressure chamber. The pressure chamber may also have an outlet designed to remove the conductive or ceramic slurry from the pressure chamber. In this way, the statistical residence time of the conductive or ceramic slurry within the apparatus can be precisely adjusted. Thus, the slurry can be removed from the pressure chamber not only through the circumference of the microgravure roll, but also discharged through the outlet using a controlled mass flow. If the residence time is too long, the conductive or ceramic slurry will tend to agglomerate the conductive or ceramic raw material particles, which will increasingly change the particle diameter distribution. This will then accelerate sedimentation and significantly affect the porosity of the separator film or electrode diverter.

[0021] The pressure chamber doctor blade may have a pressurized reservoir upstream of the feed section and / or downstream of the discharge section to prevent pressure fluctuations within the pressure chamber. This additional volume for the conductive or ceramic slurry is fluidly connected to the pressure chamber and assists in distributing the conductive or ceramic slurry along the length of the pressure chamber doctor blade parallel to the longitudinal axis of the microgravure roll. Transient effects, such as fluctuations in the rotational speed of the microgravure roll or fluctuations in the mass flow provided by a pump, can cause pressure fluctuations within the pressure chamber doctor blade. The large amount of conductive or ceramic slurry within the pressure chamber doctor blade prevents the amplitude of these pressure fluctuations. Therefore, the additional volume provided by the pressurized reservoir allows the volume of the pressure chamber to be kept small, preventing pressure fluctuations within the pressure chamber from adversely affecting porosity or coating thickness. At the same time, the small volume of the pressure chamber also prevents sedimentation within the pressure chamber.

[0022] Furthermore, the apparatus may include a filter unit for filtering the conductive slurry or the ceramic slurry, the filter unit being fluidly connected to the pressure chamber doctor blade and positioned upstream of the inlet.

[0023] Specifically, the feed line may include at least one nozzle through which the conductive or ceramic slurry can be dispensed into the pressurized chamber, the at least one nozzle configured to induce a rotational flow field within the pressurized chamber. Due to the narrowing of the flow cross section within the nozzle, the conductive or ceramic slurry accelerates before entering the pressurized chamber. The inlet angle of the nozzle is oriented away from the geometric center of gravity of the pressurized chamber, thereby inducing a rotational flow field. This ensures continuous mixing of the conductive or ceramic slurry within the pressurized chamber and prevents agglomeration. Furthermore, the rotational flow field creates a velocity gradient near the walls of the pressurized chamber, which prevents settling on the walls of the pressurized chamber or deteriorates the formation of a sedimentation layer.

[0024] The feed line may include at least two nozzles, each with a different inlet position and / or inlet angle to induce a rotational flow field. The at least two nozzles may have two opposing inlet angles and positions on either side of the pressurized chamber. The at least two nozzles may be configured to alternately change the rotation direction of the rotational flow field. For this purpose, the nozzles may be designed to individually control the dispensed mass flow of the conductive slurry or ceramic slurry. Alternatively or additionally, the inlet may have a swirl flap. Preferably, the rotation axis of the rotational flow field may be parallel to the rotation axis of the microgravure roll. Furthermore, the pressurized chamber may have a guide wall shape designed to induce a rotational flow field.

[0025] The apparatus may include a first guide roll and a second guide roll configured to guide the sheet-like carrier material onto the circumferential portion of the microgravure roll.

[0026] This is advantageous for the transfer of conductive or ceramic slurries in the so-called kiss-coating process. The microgravure roll is positioned between two guide rolls on the carrier material, and a coating line (kiss-coating line) is formed between the gravure roll and the web. The overloading of the gravure roll by the overpressure in the pressure chamber and the resulting full-surface contact of the coating liquid with the web in the kiss-coating line region ensure a uniform coating of the sheet-like carrier material.

[0027] The circumferential section may have a wrap angle of between 5° and 30°, preferably between 8° and 22°.

[0028] The diameter of the first guide roll and / or the second guide roll may be larger than the diameter of the microgravure roll, and specifically may be several times larger than the diameter of the microgravure roll.

[0029] The diameter of the first guide roll and / or the second guide roll may be smaller than the diameter of the microgravure roll. As a result, the microgravure roll can be positioned with a short distance between the first guide roll and the second guide roll. This provides good contact between the web guided between the first guide roll and the second guide roll and the microgravure roll. This favors the transfer of the conductive or ceramic slurry applied by the microgravure roll to the web. This allows for the formation of a narrow kiss coating line between the gravure roll and the web at a moderate wrap angle.

[0030] The apparatus may further be configured to move the pressure chamber doctor blade horizontally and oscillate relative to the longitudinal axis of the microgravure roll, thereby enabling solids / agglomerates adhering to the pressure chamber doctor blade to be removed, which can then be transported and filtered with the circulating fluid.

[0031] The setting of the delivery doctor blade of the pressure chamber doctor blade can be positive or negative (also referred to as trailing or piercing). Depending on the properties of the conductive or ceramic slurry, this variability in doctor blade position can have a positive impact on the quality of the coating film.

[0032] The pressure chamber doctor blade type may further comprise a minimized pressure chamber, which has a minimized volume for the conductive or ceramic slurry. By minimizing the volume, surfaces on which sediment can accumulate are avoided. The delivery doctor blade and / or the receiving doctor blade may be designed on both sides as negatively angled doctor blades. Alternatively or in addition to the outlet, the pressure chamber doctor blade may have an overflow body for removing excess conductive or ceramic slurry from the pressure chamber.

[0033] Finally, an assembly for producing a separator film or an electrode diverter is claimed, the assembly comprising an apparatus for coating a sheet-like carrier material according to any one of the above embodiments, the sheet-like carrier material, at least one deflection roll, and a dryer, wherein the at least one deflection roll is designed to transport the sheet-like carrier material from the apparatus for coating the sheet-like carrier material to the dryer.

[0034] Conductive adhesion promoters may be provided for use in electrodes of batteries, including lithium polymer batteries, to ensure adhesion of the active anode or cathode mass to the respective current collectors, i.e., no delamination should occur during battery operation (charging / discharging).

[0035] Conductive adhesion promoters can be made with Henkel's Bonderite or LOCTIDE EDAG. Conductive adhesion promoters can also be made with polymer binders based on metal oxides or polyacrylic acid, optionally with conductive additives. Alternatively, adhesion promoters can be made with rubbers based on polyolefins, polyvinyl ethers, polystyrene, or styrene-butadiene rubber.

[0036] The separator films or electrode diverters (also called current collectors) may preferably be in the form of foil, fiber, nonwoven, mesh, smooth, textured or perforated.

[0037] The conductive slurry may include, for example, a conductive polymer such as polypyrrole, polyaniline, or polythiophene. Alternatively, the conductive slurry may consist of a filled plastic provided with carbon black, graphite, and / or metal powder as a filler material. Additionally, the conductive slurry may include metals such as silver, copper, tin, aluminum, titanium, chromium, and / or nickel. Alternatively, the metal may be present as a coating on a plastic film or other material.

[0038] Surprisingly, the use of conductive slurries has shown that problems, especially with (micro)foam formation, are significantly reduced compared to conventional engraving processes. This is accompanied by a reduction in the occurrence of coating defects (pinholes), which has a positive impact on the functionality of the applied layer / battery.

[0039] The active anode mass and active cathode mass, together with the current collector to which they are applied, form an electrode. Transition metal oxides such as Co(III) oxide, Ni(II) oxide, Mn(IV) oxide, tungstate, molybdate, titanate, ferrate, and / or chromate can be used as the active mass for the cathode, as can Li-containing forms such as LiCoO, LiNiO, and LiMnO. Graphite, carbon, soot, and / or fibers can be used as the active mass for the anode.

[0040] An important component of the anode or cathode mass is an adhesion promoter. Adhesion promoters typically ensure the adhesion of the material to the current collector. The goal of the transition metal oxide or carbon adhesion or bonding is to create a bond to the current collector that is stable, i.e., does not exhibit any delamination, even over a cycling period of more than 200 cycles. Furthermore, the adhesion promoter must be stable so that mechanical stresses, such as buckling or pressing pressure, do not cause cracking, delamination, or displacement from the current collector. Polymers can be used as adhesion promoters to ensure the adhesion of the anode or cathode material to the current collector while being insensitive to processes and ion exchange reactions within the battery system.

[0041] For example, polyolefins such as polyisobutene, EPDM rubber, and / or styrene-butadiene (isoprene) polymers are used as adhesion promoters. The molecular weight of the polymers can be 20,000 to 2,000,000, preferably 50,000 to 300,000. The amount used is 2 to 25 wt%, preferably 3.5 to 15 wt%.

[0042] Furthermore, electrical conductivity is also an important prerequisite for the effectiveness of the system. It may be specified that the proportion of adhesion promoter in the active anode mass or active cathode mass does not exceed 25% based on the solid mass. This may be, for example, 5-15%. To improve the electrical conductivity, it may be specified that conductive fillers such as conductive carbon black, graphite, polypyrrole, polyaniline, or the like are used. The material may be added in an amount of up to 50% by weight based on the adhesion promoter.

[0043] Further details and features of the invention are illustrated and explained with the aid of the drawings. [Brief explanation of the drawings]

[0044] [Figure 1A] 1 shows a schematic diagram of a prior art device;

[0045] [Figure 1B] 1 shows a detailed enlarged view of the surface of a microgravure roll in a prior art device.

[0046] [Figure 2A] 1 shows a schematic diagram of an apparatus according to the present invention;

[0047] [Figure 2B] 1 shows a detailed enlarged view of the surface of the microgravure roll in an apparatus according to the invention.

[0048] [Figure 3]1 shows a detailed view of one embodiment of a pressure chamber doctor blade according to the present invention.

[0049] [Figure 4] 1 shows a detailed view of one embodiment of a pressure chamber doctor blade according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0050] FIG. 1 shows a schematic diagram of a typical apparatus for coating a sheet-like carrier material 1. The sheet-like carrier material 1 is transported in a feed direction 11 and guided onto a gravure roll 2. In this case, a conductive or ceramic slurry 3 is transferred to the sheet-like carrier material 1 via the gravure roll's circumference 21, thereby coating it. A flashing chamber is located next to the gravure roll 2. In this flashing chamber, the conductive or ceramic slurry is applied under air pressure and finally transferred to the gravure roll's circumference 21. Such an apparatus has significant drawbacks with regard to the quality of the final separator film as well as the economic efficiency of the manufacturing process. First, air is introduced into the conductive or ceramic slurry 1. Second, the conductive or ceramic slurry 1 tends to settle in the flashing chamber. Third, depending on the rotation speed of the gravure roll, the conductive or ceramic slurry 1 begins to splash off at a certain web feed speed. Another problem is the small scoop volume of the gravure roll 2 due to the thin thickness of the separator film. As a result, the structures introduced into the circumference 21, such as lines or cups, are also very fine. In the devices known from the prior art, even at moderate carrier material velocities, problems of filling the cups or lines occur.

[0051] This is illustrated in the detailed enlargement of "A" shown in FIG. 1A. A greatly enlarged section of the circumference 21 of the gravure roll is shown at a position just before the conductive or ceramic slurry 3 is transferred to the carrier material 1. In the flash chamber, the conductive or ceramic slurry 1 is transferred to the surface 21 of the gravure roll. Due to the air pressure in the flash chamber and the negligible geographic pressure of the liquid column, even at carrier material speeds of less than 100 m / min, only the cups inserted into the surface are filled with the conductive or ceramic slurry. The carrier material is then coated with a patchy or discontinuous thickness while the conductive or ceramic slurry 3 is transferred to the carrier material 1.

[0052] 2A shows a schematic diagram of an apparatus according to the invention. A sheet-like carrier material 1 is transported in a feed direction 11 and guided by a first guide roll 5 and a second guide roll 6 onto a circumferential section 22 of a microgravure roll 2 in a so-called kiss coating process. In this case, a conductive or ceramic slurry 3 is transferred to the sheet-like carrier material 1 via the circumference 21 of the gravure roll, thus coating the carrier material. For this purpose, the feed direction 11 and the direction of rotation 23 of the microgravure roll 2 are opposite. The coated sheet-like carrier material is then transported via a rubberized deflection roll 7 to a dryer (not shown), where the conductive or ceramic slurry 3 is dried by evaporating the solvent.

[0053] The conductive or ceramic slurry 3 is transferred under positive pressure to the circumference 21 of the microgravure roll 2 below the microgravure roll 2 by the pressure chamber doctor blade 4. The pressure chamber doctor blade 4 is shown here as a notch. The pressure chamber doctor blade has a pressure chamber 41 adjacent to the microgravure roll 2 and sealed off from the environment of the apparatus. For this purpose, the pressure chamber doctor blade 4 has a pair of doctor blades that seal the pressure chamber 41 across the entire width of the microgravure roll in the direction of rotation 23 or opposite to the direction of rotation 23, so that a positive pressure can be created in the pressure chamber 41. The conductive or ceramic slurry 3 is fed into the pressure chamber 41 via a feed line 42.

[0054] A pressurized reservoir 44 is arranged upstream of the inlet in the pressure chamber doctor blade 4, thereby suppressing or reducing operating pressure fluctuations in the pressure chamber doctor blade 4. The pressure chamber doctor blade 4 is supplied with the conductive or ceramic slurry 3 via a feed line equipped with a pump and filter unit (not shown). The pressure chamber 41 further includes an outlet 43 configured to remove the conductive or ceramic slurry 3 from the pressure chamber 41. The pressurized reservoir 44 is also arranged downstream of the outlet. A controlled mass flow of the conductive or ceramic slurry 3 can be removed via a drain. Positive pressure in the pressure chamber can be ensured via a throttle or controllable valve and / or pump pressure. Thus, the statistical residence time of the conductive or ceramic slurry 3 in the pressure chamber doctor blade 4 can be affected. Specifically, the discharged conductive or ceramic slurry 3 can be mixed into the feed line and thus recirculated.

[0055] The positive pressure in the pressurizing chamber 41 allows the cups of the microgravure roll to fill more quickly. Similar to the close-up shown in FIG. 1A, a close-up of the surface of the microgravure roll 2 of an apparatus according to the present invention is shown in FIG. 2B. Downstream of the pressurizing chamber, the gravure roll can be easily "overdosed" by adjusting the positive pressure. The positive pressure gradient between the pressurizing chamber 41 and ambient pressure causes additional conductive or ceramic slurry 3 to flow downstream below the pressurizing chamber doctor blade 4, overfilling the cups on the surface of the microgravure roll 1. This is advantageous for transferring the conductive or ceramic slurry 3 during the kiss coating process. The overfilling of the gravure roll 2 and the resulting full-surface contact of the coating liquid with the carrier material 1 in the kiss coating line region maintain uniform coating even at carrier material speeds well above 100 m / min.

[0056] FIG. 3 shows an alternative embodiment of the pressurized chamber doctor blade 4. Here, the feed line 42 has a nozzle 421 through which the conductive or ceramic slurry 3 is fed into the pressurized chamber. Within the nozzle, the conductive or ceramic slurry accelerates horizontally along the dashed line at the bottom of the pressurized chamber 41. This induces a rotational flow field 422 within the pressurized chamber 41. The flow field 422 rotates around a rotation axis 423 extending parallel to the rotation axis of the microgravure roll 2. The rotation of the flow field 422 is amplified by the wall-guiding shape of the pressurized chamber 41 as well as by the rotating surface 21 of the microgravure roll 2. The rotational flow field 422 mixes and thus homogenizes the conductive or ceramic slurry 3 within the pressurized chamber 41, actively preventing settling. Additionally, the rotational flow field 422 creates strong velocity gradients, and hence shear stresses, near the walls of the pressurized chamber, which inhibit sediment deposition or break up and remove wall deposits.

[0057] FIG. 4 shows another embodiment of the pressure chamber doctor blade 4 having a minimized pressure chamber 41, which has a minimized volume for the conductive or ceramic slurry 3. Minimizing the volume avoids the formation of a surface on which sediment can accumulate and minimizes the introduction of ambient air into the conductive or ceramic slurry 3 in the pressure chamber. Both the delivery doctor blade and the receiving doctor blade are designed as negatively angled doctor blades. To further reduce the volume of the pressure chamber 41, the pressure chamber 41 does not have an outlet 43. Instead, excess conductive or ceramic slurry 3 is removed from the pressure chamber 41 via the receiving doctor blade.

[0058] The features of the invention disclosed in the above description, in the drawings and in the claims may, both individually and in any combination, be essential to the implementation of the invention.

[0059] List of reference numbers: 1. Sheet-shaped carrier material 2 Microgravure roll 3. Conductive or ceramic slurry 4 Pressure Chamber Doctor Blade 5. First induction roll 6 Second induction roll 7 Deflection Roll 11 Feed Direction 21 Microgravure roll circumference 22 Circumferential Section 23 Microgravure roll rotation direction 41 Pressurized Chamber 42 Feed Line 43 Outlet 44 Pressurized Reservoir 421 Nozzle 422 Rotating Flow Field 423 Rotation axis of the flow field α Wrap angle

Claims

1. 1. An apparatus for coating a sheet-like carrier material (1) with a conductive slurry (3) containing, for example, carbon, such as a conductive carbon black slurry and / or graphite slurry and / or activated carbon-containing slurry, or a ceramic slurry (3), comprising: The device comprises a continuously rotating microgravure roll (2) designed to transfer a conductive or ceramic slurry (3) on the circumference (21) of the microgravure roll (2) onto the sheet-like carrier material (1) transported in a feed direction (11), The device is characterized in that it has a pressure chamber doctor blade (4) designed to transfer the conductive slurry (3) or the ceramic slurry (3) onto the circumference (21) of the microgravure roll (2) under positive pressure. The device.

2. 2. The apparatus according to claim 1, wherein the feed direction (11) and the direction of rotation (23) of the microgravure roll are opposite in the region of a coating line formed between the microgravure roll (2) and the sheet-like carrier material (1).

3. 10. Apparatus according to any one of the preceding claims, wherein the pressure chamber doctor blade (4) comprises a pressure chamber (41), which is open to the microgravure roll (2) but is closed off from the environment of the apparatus.

4. 4. Apparatus according to claim 3, wherein in the pressurized chamber (41) there is a positive pressure of 50 to 800 mbar, preferably 100 to 500 mbar.

5. An apparatus according to any one of the preceding claims, wherein the microgravure roll (2) has a diameter of between 60 mm and 150 mm.

6. 10. The apparatus according to any one of the preceding claims, wherein the pressurized chamber (41) has a feed line (42) designed to feed the conductive slurry (3) or the ceramic slurry (3) into the pressurized chamber (41).

7. 10. The apparatus according to claim 1, wherein the pressurized chamber (41) has an outlet (43), and the conductive slurry (3) or the ceramic slurry (3) is discharged from the pressurized chamber (41) through the outlet (43).

8. 8. The device according to claim 6 or 7, wherein the pressure chamber doctor blade (4) has a pressure reservoir (44) upstream of the feed (42) and / or downstream of the outlet (43), the pressure reservoir (44) providing an additional volume for the conductive slurry (3) or the ceramic slurry (3) to avoid pressure fluctuations in the pressure chamber (41).

9. 9. The apparatus according to claim 6, further comprising a filter unit for filtering the conductive slurry (3) or the ceramic slurry (3), the filter unit being fluidly connected to the pressure chamber doctor blade (4) and preferably located upstream of the feed line (42).

10. 10. The apparatus according to claim 7, wherein the feed line (42) has at least one nozzle (421) through which the conductive slurry (3) or the ceramic slurry (3) can be fed into the pressurized chamber (41), and the at least one nozzle (421) is designed to induce a rotational flow field (422) in the pressurized chamber (41).

11. 11. The apparatus of claim 10, wherein the feed line (42) has at least two nozzles, each nozzle having a different inlet position and / or inlet angle to induce the rotational flow field (422).

12. 12. Apparatus according to claim 10 or 11, wherein the at least one nozzle (421) is configured to induce an axis of rotation (423) of the rotational flow field parallel to an axis of rotation of the microgravure roll (2).

13. 10. The apparatus according to claim 1, further comprising a first guide roll (5) and a second guide roll (6), the first guide roll (5) and the second guide roll (6) being designed to guide the sheet-like carrier material (1) onto the circumferential section (22) of the microgravure roll (2).

14. 14. Apparatus according to claim 13, wherein the circumferential section (22) has a wrap angle (α) of between 5° and 30°, preferably between 8° and 22°.

15. 15. An assembly for producing separator films or electrode diverters, comprising an apparatus for coating a sheet-like carrier material (1) according to any one of claims 1 to 14, the sheet-like carrier material (1), at least one deflection roll (7), and a dryer, wherein the at least one deflection roll (7) is designed to transport the sheet-like carrier material (1) from the apparatus for coating the sheet-like carrier material (1) to the dryer.

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