Device for coating a metal substrate and method thereof

Abstract

The invention relates to a device (1) for coating a metal substrate (2) for the manufacture of electrodes intended for electric battery cells for electric propulsion vehicles, the device comprising: - a first calender roll (3) rotating in a first direction (5) of rotation; - a second calender roll (4) rotating in a second direction (6) of rotation opposite the first direction (5) of rotation, the first roll and the second roll being arranged facing one another and at a distance from one another so as to define a passage for the metal substrate (2); - at least one first device (7) for feeding at least one active material (9) devoid of solvent onto the first roll (3); and - at least one first means (13) for controlling a thickness of active material on the first roll (3); - means for synchronizing the speeds of rotation of the first roll and of the second roll.

Description

Device for coating a metallic substrate and its process Technical field of the invention

[0001] The invention relates to the field of rechargeable metal-ion electric batteries for electric vehicles.

[0002] In particular, the invention relates to a device for coating a metallic substrate with at least a solvent-free active material.

[0003] The invention also relates to a method of coating a metallic substrate for the manufacture of electrodes. Technical background

[0004] Electric battery cells are formed from an assembly of electrodes of opposite polarity separated from each other by a porous separator film. The stack of electrodes is arranged in a casing or bag, filled with an electrolyte.

[0005] The electrodes are manufactured from a metallic substrate, said metallic substrate is then coated with an ink containing at least one active material and at least one solvent.

[0006] The metallic substrates are coated using a coating device. They are then dried to remove the solvent. Drying is carried out in a drying oven where the electrodes are heated and continuously rotate. Electrode drying is energy-intensive. Therefore, solvent removal has a significant financial and environmental impact. Furthermore, solvents can be carcinogenic, mutagenic, and reprotoxic, posing a risk to operators.

[0007] To eliminate the use of solvents in inks, manufacturers have developed a solvent-free coating technique known as "dry process." This coating technique involves depositing solvent-free active material and additives onto a metallic substrate. The substrate and active material are passed through a calender consisting of two counter-rotating rollers. In the following text, the active material and additives are simply referred to as "active material(s)."

[0008] This solvent-free coating technique has proven particularly difficult to master. In particular, it has been observed that maintaining a consistent thickness of active material on the metallic substrate over time is challenging. Frequent irregularities in the thickness of the active material are therefore observed. Current techniques thus lead to significant waste of both metallic substrate and active material, which negatively impacts the performance of production units.

[0009] The invention aims to solve the aforementioned problems.

[0010] To this end, a process for coating a metallic substrate for the manufacture of electrodes intended for electric battery cells for electric vehicles is proposed firstly, this process comprising: - a step of rotating a first calendering roller in a first direction of rotation, - a step of rotating a second calendering roller in a second direction of rotation opposite to the first direction of rotation, the first roller and the second roller being arranged opposite each other and at a distance from each other so as to define a passage for the metallic substrate, - a step of depositing, by at least a first feeding device, at least one solvent-free active material onto the first roller, - a step of controlling, by at least a first control means, the thickness of the active material deposited on the first roller,A process in which the metallic substrate continuously moves between the first and second rollers such that a first face of the metallic substrate is coated at a transfer point by the active material deposited on the first roller; a process in which the rotational speed of the first roller and the rotational speed of the second roller are substantially equal; a process in which the active material deposited on the first roller is not passed between rollers to form a film of active material before the deposition of this active material on the first roller.

[0011] Thus, the thickness of the active material on the metallic substrate remains consistent over time. Irregularities in the thickness of the active material on the substrate are virtually nonexistent. Production waste is significantly reduced.

[0012] Other additional features may be provided alone or in combination: this process further includes - a step of depositing, by at least a second feeding device, at least one solvent-free active material onto the second roller, and - a step of controlling, by at least a second control means, the thickness of the active material deposited on the second roller, a process in which the metallic substrate passes continuously between the first roller and the second roller so that a second face of the metallic substrate opposite to the first face is coated at the transfer point by the active material deposited on the second roller, a process in which the active material deposited on the second roller is not passed between rollers to form a film of active material before the deposit of this active material on the second roller;- This process further comprises a step of removing, by the first control means and by the second control means, excess active material deposited respectively on the first roller and on the second roller, the first control means and the second control means being scraper devices arranged at a predetermined scraping distance respectively from the first roller and the second roller; - the step of removing excess active material is carried out before the coating of the metallic substrate; - this process further comprises a cleaning operation intended to remove residual active material on the first roller and on the second roller, this cleaning step being carried out after the coating of the metallic substrate;- This process further comprises a polarization step, by a first and a second polarization means, of the active material at the outlet of the first feeding device and the second feeding device so that the active material moves respectively towards the first and second rollers; - This process further comprises a thermoregulation step of the first roller and the second roller.

[0013] Secondly, a device for coating a metallic substrate for the manufacture of electrodes for electric battery cells for electric vehicles is proposed, comprising: - a first rolling mill rotating in a first direction of rotation, - a second rolling mill rotating in a second direction of rotation opposite to the first direction of rotation, the first and second mills being arranged opposite each other and at a distance from each other so as to define a passage for the metallic substrate, - at least one first device for supplying at least one solvent-free active material to the first mill, and - at least one first means for controlling the thickness of the active material on the first mill.a coating device in which the metallic substrate passes continuously between the first roller and the second roller such that a first face of the metallic substrate is coated at a transfer point by the active material deposited on the first roller; a coating device comprising only two rollers such that the active material deposited on the first roller has not passed between rollers to form a film of active material before the deposition of this active material on the first roller, the rotational speed of the first roller and the rotational speed of the second roller being substantially equal.

[0014] Thus, the thickness of the active material on the metallic substrate remains consistent over time. Irregularities in the thickness of the active material on the substrate are virtually nonexistent. Production waste is significantly reduced.

[0015] Other additional features may be provided alone or in combination: - this coating device further comprises at least one second device for supplying at least one solvent-free active material onto the second roller, and at least one second means for controlling the thickness of the active material on the second roller, a coating device in which the metallic substrate passes continuously between the first roller and the second roller so that a second face of the metallic substrate opposite to the first face is coated at the transfer point by the active material deposited on the second roller,a coating device comprising only two rollers such that the active material deposited on the second roller has not passed between rollers to form a film of active material before being deposited on the second roller; - the first control means and the second control means are scraper devices arranged at a predetermined scraping distance respectively from the first roller and the second roller, the first control means and the second control means being capable of removing excess active material deposited respectively on the first roller and on the second roller; - the first control means is arranged upstream of the transfer point in the first direction of rotation,and the second control means is arranged upstream of the transfer point in the second direction of rotation; - the first feeding device is arranged upstream of the first control means and downstream of the transfer point in the first direction of rotation, and the second feeding device is arranged upstream of the second control means and downstream of the transfer point in the second direction of rotation; - this coating device further comprises a first cleaning device arranged upstream of the first feeding device and downstream of the transfer point in the first direction of rotation, said first cleaning device being capable of removing a residue of active material from the first roller; - a second cleaning device arranged upstream of the second feeding device and downstream of the transfer point in the second direction of rotation.said second cleaning device being capable of removing residual active material from the second roller; - this coating device further comprises, a first polarization means capable of polarizing the active material at the outlet of the first feeding device, - a second polarization means capable of polarizing the active material at the outlet of the second feeding device, so that the active material moves from the first and second feeding devices towards the first and second rollers respectively; - the first and second rollers are temperature-controlled. Brief description of the figures

[0016] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for which reference should be made to the attached drawing in which:

[0017] This is a schematic representation of the device for coating a metallic substrate according to the invention. Detailed description of the invention

[0018] Figure 1 represents a device for coating a metallic substrate 2 for the manufacture of electrodes for electric battery cells for electric vehicles.

[0019] The coating device 1 comprises a first calendering roller 3 and a second calendering roller 4. The first and second rollers 3, 4 are arranged opposite each other and at a predetermined distance from each other so as to define a passage for the metallic substrate 2.

[0020] The first roller 3 rotates in a first direction 5 of rotation. The second roller 4 rotates in a second direction 6 of rotation opposite to the first direction 5 of rotation.

[0021] Furthermore, the coating device 1 includes at least one first device 7 for feeding the active material 9. The active material 9 is solvent-free. In one embodiment, the active material 9 includes a binder.

[0022] The coating device 1 includes a first means 13 for controlling the thickness of the active material 9 deposited on the first roller 3. The first means 13 for controlling the thickness allows a predetermined, homogeneous thickness to be obtained on the first roller 3.

[0023] The active material 9 deposited on the first roller 3 is then deposited onto a first face 10 of the metallic substrate 2. The deposition is carried out at a transfer point 11. The metallic substrate 2 moves continuously between the first and second rollers 3, 4.

[0024] Thus, the 20 mm thickness of active material on the metallic substrate is maintained at a consistent thickness over time. Irregularities in the thickness of the active material on the substrate are virtually nonexistent. Production waste is significantly reduced.

[0025] Advantageously, the coating device 1 includes at least a second active material feeding device 8 on the second roller 4. The active material is solvent-free. In one embodiment, the active material includes a binder.

[0026] The coating device 1 includes a second means 14 for controlling the thickness of the active material 9 deposited on the second roller 4. The second control means 14 makes it possible to obtain a predetermined, homogeneous thickness on the second roller 4.

[0027] The active material 9 deposited on the second roller 4 is then deposited onto a second face 12 of the metallic substrate 2 opposite the first face 10. The deposition is carried out at a transfer point 11. The metallic substrate 2 moves continuously between the first and second rollers.

[0028] Thus, the 20 mm thickness of active material on the metallic substrate is maintained at a consistent thickness over time. Irregularities in the thickness of the active material on the substrate are virtually nonexistent. Production waste is significantly reduced.

[0029] Advantageously, the coating device includes means for synchronizing the rotational speeds of the first roller 3 and the second roller 4 so that the rotational speed of the first roller and the rotational speed of the second roller are substantially equal. When the first roller 3 and the second roller 4 have different radii, the peripheral linear speed (also called the peripheral velocity) of the first roller 3 is substantially equal to the peripheral linear speed of the second roller 4. In one embodiment, the synchronization means include direct mechanical coupling (e.g., gears, a gear train, a toothed belt, or a chain) or open-loop or closed-loop electronic control circuits. The device 1 includes only two rollers 3 and 4.In other words, there are no other rollers between which the active material is first passed to form a film before depositing this active material onto the first roller.

[0030] Unlike devices where different rotational speeds are used to first form a film of active material, in this invention the coating is not applied abruptly. Indeed, when rotational speeds are different, there is a risk of damaging the active material (shearing of the active material can alter its molecular structure). These risks are virtually eliminated with this coating device 1, where the active material is only subjected to compression at the transfer point 11. The active material is pressed and stretched uniformly on each of the two faces of the metallic substrate without undergoing significant internal friction beforehand to form a film. This allows for precise control of the thickness without degrading the electrochemical properties of the active material.Indeed, state-of-the-art coating devices include more than two rollers (for example, three rollers for each side of the metallic substrate). For instance, a pair of rollers where the active material is first passed to form a film of active material, these rollers have different rotational speeds. These state-of-the-art devices also include additional rollers to apply the active material to the metallic substrate. These devices act abruptly on the active material, which is subjected to intense mechanical stresses due to the different rotational speeds of the rollers used to first form a film of active material before it is deposited on the first roller (3) and the second roller (4).

[0031] Advantageously, the first active material thickness control means 13 is a scraper device. The first control means 13 is arranged at a predetermined scraping distance 15 from the first calendering roller 3.

[0032] Similarly, the second active material thickness control means 14 is a scraper device. This second control means 14 is arranged at a predetermined scraping distance 15 from the second calendering roller 4.

[0033] The first control means 13 and the second control means 14 allow the removal of excess 16 of active material 9 deposited respectively on the first roller 3 and on the second roller 4.

[0034] The first and second control methods allow for mechanical control of the active material thickness on the first and second rollers. By controlling the active material thickness directly at the first and second rollers, production waste is significantly reduced.

[0035] Furthermore, the use of scraper devices as a means of control simplifies the architecture of the coating system, resulting in improved robustness and longevity over time.

[0036] Advantageously, the first thickness control means 13 is arranged upstream of the transfer point 11 along the first direction 5 of rotation. The second thickness control means 14 is arranged upstream of the transfer point 11 along the second direction of rotation.

[0037] The first and second control means allow for the mechanical control of the active material thickness on the first and second rollers. By controlling the active material thickness directly at the first and second rollers and before transfer point 11, production rejects are significantly reduced.

[0038] Advantageously, the coating device 1 includes a first feeding device 7. The first feeding device 7 is located upstream of the first control means 13 and downstream of the transfer point 11 in the first direction 5 of rotation. The second feeding device 8 is located upstream of the second control means 14 and downstream of the transfer point 11 in the second direction 6 of rotation.

[0039] This arrangement allows for a significant reduction in production waste.

[0040] Advantageously, the coating device 1 includes a first cleaning device 17. The first cleaning device 17 is arranged upstream of the first feeding device 7 and downstream of the transfer point 11 in the first direction 5 of rotation. The first cleaning device 17 is suitable and intended to remove a residue 19 of active material from the first roller 3.

[0041] Advantageously, the coating device 1 includes a second cleaning device 18. The second cleaning device 18 is arranged upstream of the second feeding device 8 and downstream of the transfer point 11 in the second direction 6 of rotation. The second cleaning device 18 is suitable and intended to remove a residue 19 of active material from the second roller 4.

[0042] After transfer point 11, residues of active material may form a film on the first and second rollers 3, 4. This compressed film of active material is likely to alter the calibration of the coating device 1 on the one hand and to alter the expected performance of the electrode on the other.

[0043] Advantageously, the coating device 1 includes a first polarization means suitable for polarizing the active material at the output of the first feeding device 7.

[0044] The coating device 1 includes a second polarization means suitable for polarizing the active material at the output of the second feeding device 8.

[0045] The active material then moves from the first and second feeding devices 7,8 to the first and second rollers 4,5 respectively.

[0046] These polarization devices work by creating a polarity difference between the active material to be transferred and the first and second rollers, which are, for example, grounded. This polarity difference allows the active material to be attracted to the rollers and to adhere to them up to the transfer point 11.

[0047] Advantageously, the first roller 3 and the second roller 4 are temperature-regulated.

[0048] This allows the active material to be kept in optimal conditions for coating on the metallic substrate.

[0049] The following will describe a method for coating a metallic substrate using the coating device 1.

[0050] The process includes a step of rotating the first roller 3 in the first direction of rotation.

[0051] The process includes a step of rotating the second roller in the second direction of rotation.

[0052] The process includes a deposition step by at least the first feeding device 7 of at least one solvent-free active material onto the first roller 3.

[0053] The process includes a step to control the thickness of the active material deposited on the first roller.

[0054] In this process, the metallic substrate continuously moves between the first roller 3 and the second roller 4 so that a first face 10 of the metallic substrate 2 is coated at a transfer point 11 by the active material 9 deposited on the first roller 3.

[0055] In this process, the active material deposited on the first roller is coated on the first face 10 of the metallic substrate 2.

[0056] Thus, the thickness of the active material on the metallic substrate remains consistent over time. Irregularities in the thickness of the active material on the substrate are virtually nonexistent. Production waste is significantly reduced.

[0057] Advantageously, the process includes a step of depositing, by the second feeding device 8, at least one solvent-free active material onto the second roller 4.

[0058] The process includes a step of controlling the thickness of active material deposited on the second roller 4.

[0059] In this process, the active material deposited on the second roller is coated on the second face 12 of the metallic substrate 2.

[0060] Thus, the thickness of the active material on the metallic substrate remains consistent over time. Irregularities in the thickness of the active material on the substrate are virtually nonexistent. Production waste is significantly reduced.

[0061] Advantageously, the rotational speed of the first roller 3 and the rotational speed of the second roller 4 are substantially equal. In the process, the active material is not passed between rollers to form a film of active material before being deposited on the first roller.

[0062] Unlike devices with varying rotational speeds, the coating process is not abrupt. Indeed, when rotational speeds differ, there is a risk of damaging the substrate or the active material. These risks are virtually eliminated with this coating device. By avoiding passing the active material between rollers with different speeds, it is not subjected to intense mechanical stresses that could damage it.

[0063] Advantageously, the process includes a step of removing excess 16% of active material from the first roller and the second roller. This removal step is carried out using the first control means and the second control means.

[0064] The first and second control methods allow for mechanical control of the active material thickness on the first and second rollers. By controlling the active material thickness directly at the first and second rollers, production waste is significantly reduced.

[0065] Furthermore, the use of scraper devices as a means of control simplifies the architecture of the coating system, resulting in improved robustness and longevity over time.

[0066] Advantageously, in the process the step of removing excess 16 of active material is carried out before the deposition of active material on the metallic substrate.

[0067] By controlling the thickness of active material directly at the first and second rollers and before transfer point 11, production scrap is significantly reduced.

[0068] Advantageously, the process includes a cleaning operation designed to remove residual active material from the first and second rollers. The cleaning step is carried out after the metallic substrate has been coated at transfer point 11.

[0069] After transfer point 11, residues of active material may form a film on the first and second rollers 3, 4. This compressed film of active material is likely to alter the calibration of the coating device 1 on the one hand and to alter the expected performance of the electrode on the other.

[0070] Advantageously, the process includes a polarization step of the active material at the outlet of the first and second feed devices. During this polarization step, the active material is positively polarized.

[0071] These polarization devices work by creating a polarity difference between the active material to be transferred and the first and second rollers, which are, for example, grounded. This polarity difference allows the active material to be attracted to the rollers and to adhere to them up to the transfer point 11.

[0072] Advantageously, the process includes a thermoregulation step for the first and second rollers. During this step, the first and second rollers are maintained at a set temperature.

[0073] This allows the active material to be kept in optimal conditions for coating on the metallic substrate.

Claims

A method for coating a metallic substrate (2) for the manufacture of electrodes for electric battery cells for electric vehicles, this method comprising: - a step of rotating a first calendering roller (3) in a first direction (5) of rotation, - a step of rotating a second calendering roller (4) in a second direction (6) of rotation opposite to the first direction (5) of rotation, the first roller (3) and the second roller (4) being arranged opposite each other and at a distance from each other so as to define a passage for the metallic substrate (2), - a step of depositing, by at least a first feeding device (7), at least one solvent-free active material (9) onto the first roller (3), - a step of checking, by at least a first checking means (13), the thickness of the active material (9) deposited on the first roller (3),a process in which the metallic substrate (2) continuously moves between the first roller (3) and the second roller (4) such that a first face (10) of the metallic substrate (2) is coated at a transfer point (11) by the active material (9) deposited on the first roller (3), a process in which the rotational speed of the first roller and the rotational speed of the second roller are substantially equal, a process in which the active material deposited on the first roller is not passed between rollers to form a film of active material before the deposition of this active material on the first roller. A method according to the preceding claim comprising, furthermore: - a step of depositing, by at least a second feeding device (8), at least one solvent-free active material (9) onto the second roller (4), and - a step of checking, by at least a second checking means (14), the thickness of the active material (9) deposited on the second roller (4), a method in which the metallic substrate (2) continuously moves between the first roller (3) and the second roller (4) so ​​that a second face (12) of the metallic substrate (2) opposite to the first face (10) is coated at the transfer point (11) by the active material (9) deposited on the second roller (3), a method in which the active material deposited on the second roller (3) is not passed between rollers to form a film of active material before the deposition of this active material on the second roller. Method according to claim 2, further comprising a step of removing, by the first control means and by the second control means, an excess (16) of active material deposited respectively on the first roller and on the second roller, the first control means and the second control means being scraper devices arranged at a predetermined scraping distance (15) respectively from the first roller (3) and the second roller (4). A method according to the preceding claim, wherein the step of removing excess active material is carried out before coating the metallic substrate. A method according to any one of claims 2 to 4, further comprising a cleaning operation intended to remove residual active material on the first roller and on the second roller, this cleaning step being carried out after the coating of the metallic substrate. A method according to any one of claims 2 to 5, further comprising a polarization step, by a first and a second polarization means, of the active material at the outlet of the first feeding device and the second feeding device so that the active material (9) moves respectively towards the first and second rollers (3,4). Method according to any one of the preceding claims, further comprising a thermoregulation step of the first roller (3) and the second roller (4). Device (1) for coating a metallic substrate (2) for manufacturing electrodes for electric battery cells for electric vehicles comprising: - a first rolling roll (3) rotating in a first direction (5) of rotation, - a second rolling roll (4) rotating in a second direction (6) of rotation opposite to the first direction (5) of rotation, the first roll (3) and the second roll (4) being arranged opposite each other and at a distance from each other so as to define a passage for the metallic substrate (2), - at least a first device (7) for supplying at least one solvent-free active material (9) onto the first roll (3), and - at least a first means (13) for controlling the thickness of the active material (9) on the first roll (3),coating device (1) in which the metallic substrate (2) passes continuously between the first roller (3) and the second roller (4) such that a first face (10) of the metallic substrate (2) is coated at a transfer point (11) by the active material (9) deposited on the first roller (3) coating device comprising only two rollers (3,4) such that the active material deposited on the first roller has not passed between rollers to form a film of active material before the deposition of this active material on the first roller, the rotational speed of the first roller and the rotational speed of the second roller being substantially equal. Coating device (1) according to the preceding claim, wherein it comprises: - at least one second device (8) for supplying at least one solvent-free active material (9) onto the second roller (4), and - at least one second means (14) for controlling the thickness of the active material (9) on the second roller (4), coating device (1) wherein the metallic substrate (2) passes continuously between the first roller (3) and the second roller (4) such that a second face (12) of the metallic substrate (2) opposite to the first face (10) is coated at the transfer point (11) by the active material (9) deposited on the second roller (3), coating device comprising only two rollers (3,4) such that the active material deposited on the second roller has not passed between rollers to form a film of active material before the deposition of this active material on the second roller. Coating device (1) according to the preceding claim in which the first control means (13) and the second control means (14) are scraper devices arranged at a predetermined scraping distance (15) respectively from the first roller (3) and the second roller (4), the first control means (13) and the second control means (14) being capable of removing an excess (16) of active material deposited respectively on the first roller (3) and on the second roller (4). Coating device (1) according to claim 9 or 10 wherein the first control means (13) is arranged upstream of the transfer point (11) in the first direction (5) of rotation, and the second control means (14) is arranged upstream of the transfer point (11) in the second direction (6) of rotation. Coating device (1) according to any one of claims 9 to 11 in which the first feeding device (7) is arranged upstream of the first control means (13) and downstream of the transfer point (11) in the first direction (5) of rotation, and the second feeding device (8) is arranged upstream of the second control means (14) and downstream of the transfer point (11) in the second direction (6) of rotation. Coating device (1) according to any one of claims 9 to 12, wherein it comprises: - a first cleaning device (17) arranged upstream of the first feeding device (7) and downstream of the transfer point (11) in the first direction (5) of rotation, said first cleaning device (17) being capable of removing a residue (19) of active material from the first roller (3), - a second cleaning device (18) arranged upstream of the second feeding device (8) and downstream of the transfer point (11) in the second direction (6) of rotation, said second cleaning device (18) being capable of removing a residue (19) of active material from the second roller (4). Coating device (1) according to any one of claims 9 to 13, wherein it comprises: - a first polarization means suitable for polarizing the active material (9) at the exit of the first feeding device (7), - a second polarization means suitable for polarizing the active material (9) at the exit of the second feeding device (8), so that the active material (9) moves from the first and second feeding devices (7,8) to the first and second rollers (4,5) respectively. Coating device (1) according to any one of claims 8 to 14 wherein the first roller (3) and the second roller (4) are temperature-controlled.

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