Testing system and testing procedure for electrodes

Abstract

The present disclosure relates to a test system (100) for electrodes (EL), comprising: - at least one optical sensor module (110A, 110B, 110C) configured to detect a test area for an electrode (EL); - at least one first lighting module (120) configured to illuminate the test area from a first direction (1), wherein the first direction (1) corresponds to substantially frontal illumination of the test area; - at least one second lighting module (130A, 130B) configured to illuminate the test area from a second direction (2), wherein the second direction (2) corresponds to lateral illumination of the test area; and - an analysis module (140) that is set up to perform a quality check and / or defect detection of the electrode (EL) based on acquisition data (ED) from at least one optical sensor module (110A, 110B, 110C).

Description

[0001] The present disclosure relates to a testing system for electrodes, a roll-to-roll system for the production of battery cells, a testing method for electrodes, and a storage medium for executing the testing method. The present disclosure relates in particular to an illumination strategy for testing an electrode using an optical system. State of the art

[0002] A key step in the production of lithium-ion cells is the electrode coating process, which must meet the highest quality standards. For example, particles larger than 50 µm can cause short circuits in the finished cells, significantly impacting both their lifespan and safety. Failure to comply with these stringent requirements makes the production of a safe product impossible.

[0003] Conventional optical inspection methods for electrodes often involve illuminating the electrodes and capturing the image with cameras. Typically, the illumination is from above, with the light reflected from the electrode and back into the camera to reveal surface defects. These common methods allow for the identification of larger defects such as particles or uncoated areas.

[0004] However, it has become apparent that existing testing methods and lighting strategies struggle to reliably detect minor defects, such as missing stripes in the coating or horizontal damage like waviness. This poses a problem because these small defects often go undetected and can compromise product quality. In particular, the testing methods used so far are primarily designed to identify large and highly visible defects, while smaller and more subtle defects are frequently overlooked. Disclosure of the invention

[0005] The purpose of this disclosure is to provide a testing system for electrodes, a roll-to-roll system for the production of battery cells, a testing method for electrodes, and a storage medium for executing the testing method, all of which are capable of reliably detecting even the smallest defects in the electrode. In particular, the purpose of this disclosure is to ensure compliance with quality requirements for electrodes, e.g., those of lithium-ion batteries.

[0006] This problem is solved by the subject matter of the independent claims. Advantageous embodiments are specified in the dependent claims.

[0007] According to an independent aspect of the present disclosure, a test system for electrodes, in particular of battery cells, is specified. The test system comprises: - at least one optical sensor module configured to detect a test area for an electrode; - at least one first lighting module configured to illuminate the test area from a first direction, the first direction being substantially frontal illumination of the test area; - at least one second lighting module configured to illuminate the test area from a second direction, the second direction corresponding to lateral illumination of the test area; and - an analysis module that is set up to perform a quality check and / or defect detection of the electrode based on acquisition data from at least one optical sensor module.

[0008] According to the invention, the test area is illuminated both frontally and laterally. In particular, the frontal illumination is directed, for example, in the direction of the electrode's path, to detect defects occurring horizontally with respect to the path. Additionally, the electrode is illuminated laterally, creating shadows that make defects more clearly visible to the optical sensor, thus enabling the detection of even very fine defects in the electrode. The combination of frontal and lateral illumination significantly improves the detection of defects, including small and horizontal ones. In this way, the high quality requirements for electrodes, for example, for lithium-ion batteries, can be reliably met.

[0009] The analysis module may include software components / algorithms that are set up to run on at least one processor and thereby perform the functionalities of the analysis module.

[0010] The term "test area" refers to a specific area or section, e.g. within a roll-to-roll system, in which the electrode is subjected to a quality test.

[0011] The electrode is a conductive component that serves as either the anode (negative electrode) or the cathode (positive electrode). Such an electrode typically consists of an active material applied to a substrate using a coating process. The substrate is, for example, a metallic foil, such as copper for the anode or aluminum for the cathode. This substrate serves as a carrier for the active material, which is applied via the coating process. In this process, a mixture of active materials (such as graphite for the anode or lithium metal oxides for the cathode), binders, and conductive additives is evenly applied to the substrate. After application, the coating is usually dried and calendered to obtain a uniform and dense layer.

[0012] Preferably, the analysis module is configured to perform quality control and / or defect detection by analyzing a shadow cast on the electrode surface. A shadow is cast on the electrode surface when incident light strikes irregularities or protrusions on the electrode. These defects partially or completely block the light, making dark areas or shadows visible on the opposite side of the defect. The shadow highlights the shape and structure of the defects, making them more clearly visible to the optical sensor module because the contrasts between illuminated and unilluminated areas make them stand out more.

[0013] Preferably, the at least one first illumination module is arranged above the test area to illuminate the electrode frontally from above. The term "above" means that the at least one first illumination module is physically positioned above the test area. It is therefore located directly above the test area and thus the electrode under test, so that the light falls onto the electrode essentially perpendicularly from above. This arrangement of the at least one first illumination module enables frontal illumination, in which the light strikes the electrode from above and is reflected from its surface to make defects visible.

[0014] Preferably, the first direction is essentially perpendicular to a path direction of a substrate coated with the electrode that moves through the test area.

[0015] The term "path direction" refers to the direction of movement of the substrate coated with the electrode as it is guided through a manufacturing system, such as a roll-to-roll system.

[0016] The term "perpendicular" refers to an essentially perpendicular alignment, e.g., of directions and / or surfaces, whereby a deviation of a few degrees, e.g., up to 5° or even up to 10°, from a perfectly perpendicular alignment is still considered an "essentially perpendicular alignment." Similarly, the term "parallel" refers to an essentially parallel alignment, e.g., of directions and / or surfaces, whereby a deviation of a few degrees, e.g., up to 5° or even up to 10°, from a perfectly parallel alignment is still considered an "essentially parallel alignment."

[0017] Preferably, the first direction is essentially perpendicular to a surface of the electrode.

[0018] Preferably, the second direction is essentially perpendicular to the path direction of the substrate coated with the electrode.

[0019] Preferably, the second direction is essentially parallel to the surface of the electrode. In particular, the at least one second illumination module can be arranged laterally at the same height as the electrode and / or the substrate to ensure optimal illumination.

[0020] Preferably, the second direction is essentially perpendicular to the first direction.

[0021] Preferably, the at least one second illumination module comprises a first lateral illumination module and a second lateral illumination module arranged on opposite sides of the test area, so that the electrode is illuminated from both sides. This two-sided illumination further improves defect detection.

[0022] Preferably, the first and second side lighting modules are arranged offset along the direction of travel. In other words, the first and second side lighting modules cannot be directly opposite each other, thus increasing the amount of shadow cast.

[0023] Preferably, the at least one first lighting module comprises, or is, an LED strip. The at least one first lighting module can be configured, in particular, to enable high intensity and precise direction of the light.

[0024] Preferably, the at least one second lighting module comprises, or is, an LED strip. The at least one second lighting module can be configured, in particular, to enable high intensity and precise direction of the light.

[0025] Preferably, the at least one optical sensor module comprises at least one first optical sensor module configured to detect the test area from the first direction; and at least one second optical sensor module configured to detect the test area from the second direction.

[0026] Preferably, the at least one second optical sensor module comprises a first lateral sensor module and a second lateral sensor module arranged on opposite sides of the test area, so that the electrode is detected from both sides. Detection from both sides further improves defect detection.

[0027] Preferably, the at least one optical sensor module comprises, or is, a line scan camera. In particular, the at least one first optical sensor module and / or the at least one second optical sensor module (e.g., the first lateral sensor module and / or the second lateral sensor module) can comprise or be a line scan camera.

[0028] A line scan camera is a special type of camera that does not capture image information as a complete image all at once, but rather line by line. Unlike a conventional area scan camera, which captures a two-dimensional image with a fixed number of pixels in height and width, the sensor of a line scan camera consists of a single row of pixels.

[0029] However, the embodiments of the present disclosure are not limited to line scan cameras and other types of optical sensors, in particular cameras, can be used.

[0030] According to another independent aspect of the present disclosure, a roll-to-roll plant for the manufacture of battery cells is specified. The roll-to-roll plant includes the testing system according to the embodiments of the present disclosure.

[0031] A roll-to-roll system is a production system designed to continuously unwind flexible materials, such as films or tapes, from a take-up reel, guide them through various processing steps, and then wind them onto a take-up reel. Guide rollers (also known as "guide rollers") serve to precisely guide and support the flexible materials in the desired direction and control their movement to ensure consistent processing.

[0032] The roll-to-roll system described in this disclosure can be a coating system. A coating system designed as a roll-to-roll system is a specialized production system that continuously processes flexible materials such as films, tapes, or other substrates by unwinding them from a take-up reel, passing them through one or more coating stations, and then rewinding them onto a take-up reel. During transport through the system, the flexible material is coated with a layer of liquids, pastes, or powder materials. The coating can be applied in various forms, such as wet coating, dry coating, or by applying thin films using methods like slot-die coating, roller coating, or spray coating.

[0033] The roll-to-roll system described in this disclosure can be an electrode coating system for the production of battery cells, such as lithium-ion cells. In such an electrode coating system, an active material (e.g., lithium metal oxide or graphite) can be applied to a metallic substrate (e.g., aluminum or copper).

[0034] Preferably, the test area is arranged on a guide roller of the roll-to-roll system. In particular, a portion of the electrode that rests on or is supported by the guide roller can be tested.

[0035] According to another independent aspect of the present disclosure, a test method for electrodes, in particular of battery cells, is specified. The test method comprises: - Illuminating, by means of at least a first illumination module, a test area for an electrode from a first direction, wherein the first direction corresponds to a substantially frontal illumination of the test area; - Illuminating the test area from a second direction by means of at least one second lighting module, wherein the second direction corresponds to lateral illumination of the test area; - Detection of the test area by means of at least one optical sensor module; and - Performing, through an analysis module, a quality check and / or defect detection of the electrode based on acquisition data from at least one optical sensor module.

[0036] The electrode testing procedure can implement the aspects of the electrode testing system described in this document.

[0037] According to another independent aspect of the present disclosure, a software (SW) program is specified. The SW program can be configured to run on one or more processors and thereby perform the electrode testing procedure described in this document.

[0038] According to another independent aspect of the present disclosure, a storage medium is specified. The storage medium may include a software program configured to run on one or more processors and thereby execute the electrode testing procedure described in this document.

[0039] According to another independent aspect of the present disclosure, software with program code is specified. The software is designed to carry out the testing procedure for electrodes when the software runs on one or more software-controlled devices.

[0040] According to another independent aspect of the present disclosure, a system is specified. The system comprises one or more processors; and at least one memory connected to the one or more processors and containing instructions that can be executed by the one or more processors to perform the electrode testing procedure described in this document.

[0041] A processor or processor module is a programmable computing unit, i.e., a machine or an electronic circuit that controls other elements according to given instructions and thereby advances an algorithm (process). Brief description of the drawings

[0042] Examples of the manifestation of the revelation are shown in the figures and are described in more detail below. They show: Fig. 1 schematically a side view of a test system for electrodes according to embodiments of the present disclosure, Fig. 2 schematically a top view of a test system for electrodes according to embodiments of the present disclosure, and Fig. 3 a flowchart of a test procedure for electrodes according to embodiments of the present disclosure. Implementations of the revelation

[0043] Unless otherwise noted, the same reference symbols are used for identical and equivalent elements in the following.

[0044] Fig. Figure 1 schematically shows a side view of a test system 100 for electrodes according to embodiments of the present disclosure. Fig. Figure 2 schematically shows a top view of the test system 100.

[0045] In some embodiments, the test system 100 can be part of a battery cell production plant or can be connected to the production plant. The production plant can, for example, be a roll-to-roll plant for the manufacture of battery cells, but the present disclosure is not limited to this.

[0046] The electrode is a conductive component that serves either as an anode (negative electrode) or a cathode (positive electrode). Such an electrode typically consists of an active material applied to a substrate using a coating process, for example, in a roll-to-roll system. The substrate is, for instance, a metallic foil, such as copper for the anode or aluminum for the cathode. This substrate serves as a carrier for the active material, which is applied via the coating process.

[0047] The test system 100 for the electrode EL applied to the substrate SUB by means of the coating process comprises at least one optical sensor module 110A, 110B, 110C configured to detect a test area for an electrode EL; at least one first illumination module 120 configured to illuminate the test area from a first direction 1, wherein the first direction 1 corresponds to substantially frontal illumination of the test area or the electrode EL; at least one second illumination module 130A, 130B configured to illuminate the test area from a second direction 2, wherein the second direction 2 corresponds to lateral illumination of the test area or the electrode EL; and an analysis module 140 configured to perform a quality check and / or defect detection of the electrode EL based on detection data ED from the at least one optical sensor module 110A, 110B, 110C.

[0048] Regarding the Fig. 2 and Fig. 3. It should be noted that the arrangement of the lighting modules and sensor modules side by side and / or one above the other is merely exemplary. Other spatial arrangements are also possible that are equally suitable for carrying out the functions according to the invention.

[0049] The test area is a specific area or section, e.g., within the roll-to-roll system, where the electrode EL is subjected to a quality inspection. In some embodiments, the test area is located on a guide roller of the roll-to-roll system (not shown). In particular, a portion of the electrode EL that rests on or is supported by the guide roller can be tested.

[0050] The analysis module 140 can be configured to perform quality control and / or defect detection by analyzing shadows cast on the surface of the EL electrode. A shadow is cast on the electrode surface when incident light strikes irregularities or protrusions on the electrode. The shadow highlights the shape and structure of the defects, making them more easily detectable by the optical sensor modules 110A, 110B, and 110C, as the contrast between illuminated and unilluminated areas increases their visibility.

[0051] In some embodiments, the at least one first lighting module 120 comprises, or is, an LED strip. The at least one first lighting module 120 can be configured, in particular, to enable high intensity and precise direction of the light.

[0052] In some embodiments, the at least one first illumination module 120 is arranged above the test area to illuminate the electrode EL frontally from above, so that the light falls onto the electrode EL essentially perpendicularly from above. In other words, the first direction 1 can be essentially perpendicular to a surface of the electrode EL. This arrangement of the at least one first illumination module 120 enables frontal illumination, in which the light strikes the electrode from above and is reflected from its surface, for example, to make horizontal defects visible.

[0053] The first direction 1 can be essentially perpendicular to a path direction 3 of the substrate SUB coated with the electrode EL, which moves through the test area. The path direction denotes the direction of movement of the substrate SUB coated with the electrode EL as it is guided through a manufacturing system, such as a roll-to-roll system.

[0054] The second direction 2 can also be essentially perpendicular to the path direction 3 of the substrate SUB coated with the electrode EL, and in particular can be essentially parallel to the surface of the electrode EL. For example, the at least one second illumination module 130A, 130B can be arranged laterally at the same height as the electrode EL and / or the substrate SUB to ensure optimal illumination.

[0055] In some embodiments, the at least one second lighting module 130A, 130B comprises, or is, an LED strip. The at least one second lighting module 130A, 130B can be configured, in particular, to enable high intensity and precise direction of the light.

[0056] In some embodiments, the at least one second illumination module 130A, 130B comprises a first lateral illumination module 130A and a second lateral illumination module 130B, which are arranged, for example, along the second direction 2 on opposite sides of the test area, so that the electrode EL is illuminated from both sides. This two-sided illumination can further improve defect detection. In some embodiments, it can be advantageous if the first lateral illumination module 130A and the second lateral illumination module 130B are not directly opposite each other or are offset along the path direction 3 (not shown), so that shadowing can be increased.

[0057] In some embodiments, the at least one optical sensor module 110A, 110B, 110C comprises at least one first optical sensor module 110A configured to detect the test area from the first direction 1; and at least one second optical sensor module 110B, 110C configured to detect the test area from the second direction 2.

[0058] The at least one second optical sensor module 110B, 110C can comprise a first lateral sensor module 110B and a second lateral sensor module 110C, which are arranged, for example, along the second direction 2 on opposite sides of the test area, so that the electrode EL is detected from both sides. Detection from both sides can further improve defect detection.

[0059] In some embodiments, the at least one optical sensor module 110A, 110B, 110C comprises, or is, a line scan camera. In particular, the at least one first optical sensor module 110A and / or the at least one second optical sensor module 110B, 110C (e.g., the first lateral sensor module 110A and / or the second lateral sensor module 110C) can comprise or be a line scan camera.

[0060] Fig. Figure 3 schematically shows a flowchart of a test method 300 for electrodes according to embodiments of the present disclosure. The test method 300 can be implemented by suitable software that can be executed by one or more processors (e.g., a CPU).

[0061] The test method 300 comprises, in block 310, illumination of a test area for an electrode from a first direction by at least one first illumination module, wherein the first direction corresponds to substantially frontal illumination of the test area; in block 320, illumination of the test area from a second direction by at least one second illumination module, wherein the second direction corresponds to lateral illumination of the test area; in block 330, detection of the test area by at least one optical sensor module; and in block 340, performance of a quality check and / or defect detection of the electrode by an analysis module based on detection data from the at least one optical sensor module.

[0062] According to the invention, the test area is illuminated both frontally and laterally. In particular, the frontal illumination is directed, for example, in the direction of the electrode's path, to detect defects occurring horizontally with respect to the path. Additionally, the electrode is illuminated laterally, creating shadows that make defects more clearly visible to the optical sensor, thus enabling the detection of even very fine defects in the electrode. The combination of frontal and lateral illumination significantly improves the detection of defects, including small and horizontal ones. In this way, the high quality requirements for electrodes, for example, for lithium-ion batteries, can be reliably met.

[0063] Although the invention has been further illustrated and explained in detail by means of preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived from them by a person skilled in the art without departing from the scope of protection of the invention. It is therefore clear that a multitude of possible variations exist. It is also clear that the embodiments mentioned as examples are truly only examples and are not to be understood in any way as limiting, for example, the scope of protection, the possible applications, or the configuration of the invention.Rather, the preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete terms, whereby the person skilled in the art, with knowledge of the disclosed inventive concept, can make various changes, for example with regard to the function or the arrangement of individual elements mentioned in an exemplary embodiment, without leaving the scope of protection defined by the claims and their legal equivalents, such as further explanations in the description.

Images