Method of quality control for an electrochemical storage device, sensor device for the same, and method of manufacturing an electrochemical energy storage device

Abstract

Sensor devices and methods for detecting defects in a test sample based on combined thermography sensing and eddy current sensing. A sensor device is provided for detecting defects in a test sample using an eddy current sensor and a thermal camera, and a method is provided for detecting defects in a test sample by generating an eddy current in the test sample, detecting a variation in the eddy current, detecting a thermal image of the test sample, and determining a quality parameter based on the variation in the eddy current and the thermal image. Systems and methods are further provided for manufacturing an electrochemical energy storage device, particularly an electrode for any electrochemical energy storage device, using the sensor device.

Description

[0001] METHOD OF QUALITY CONTROL FORAN ELECTROCHEMICAL STORAGE DEVICE, SENSOR DEVICE FOR THE SAME, AND METHOD OF MANUFACTURING AN ELECTROCHEMICAL ENERGY STORAGE DEVICE

[0002] TECHNICAL FIELD

[0003] Embodiments of the present disclosure relate to methods and apparatus for improved quality control of electrochemical energy storage devices. Particularly, embodiments of the present disclosure relate to methods and apparatus for combined eddy current and thermography sensing of defects in components of electrochemical energy storage devices, particularly in coated electrodes of lithium-ion battery cells or in housings of lithium-ion battery cells, and particularly wherein the sensing is performed in-situ.

[0004] BACKGROUND

[0005] In the manufacturing of electrochemical energy storage devices, in particular lithium-ion battery cells, significant efforts are invested in reducing scrap rates of components and completed devices. Accordingly, the development of non-destructive, non-contact testing and quality control systems has been a major focus for detecting defective components and materials.

[0006] One area in particular where defects can occur is in the deposition of electrode active material onto an electrode substrate, as well as the subsequent drying and calendering processes. Defects in the deposited layers of electrode active material may be surface-level defects such as cracking or pitting. However, subsurface-level defects such as poor adhesion between the substrate and the electrode active material, voids in the layers of electrode active material or corrosion of the electrode substrate may be particularly difficult to detect.

[0007] Another area where defects can occur is in the final assembly of the electrochemical energy storage device into a housing. Quality issues and defects may arise in any one of the processes of welding / forming the housing, forming burst perforations in the housing, assembling an electrode stack into the housing, filling the housing with electrolyte and sealing the housing. For example, the detection and quality control of welding quality of welded joints, the proper positioning of insulation material, homogeneity of the filled electrolyte or levels of electrolyte impregnation are important. Further, the detection of defects in the housing material itself, such as cracks, impurities or corrosion, is important for ensuring quality and safety of the finished device and for identifying if material, electrodes or completed devices should be reworked or scrapped.

[0008] Non-destructive and non-contact methods are known in the state of the art for detecting surfacelevel and subsurface-level defects in electrochemical energy storage devices. For example, some manufacturers have been implementing computer tomography (CT) scanning into electrode manufacturing processes and cell assembly processes for quality control purposes. Alternative solutions include outfitting the respective processes with a number of cameras and computer vision systems for visual quality control.

[0009] However, the existing methods have significant disadvantages. CT scanning, for example, has a high up-front cost for installation, requires costly setup and maintenance, are substantially large and bulky devices, and require a significant amount of time to carry out quality control processes per electrode or per device. On the other hand, although the installation of cameras is less costly than CT scanning, computer vision systems which rely on cameras or similar optical sensors are not capable of detecting subsurface-level defects.

[0010] In view of the deficiencies in the current state of the art, improved apparatus and methods for quality control of electrochemical energy storage devices, particularly for the electrodes and / or the housings thereof, are sought.

[0011] SUMMARY In view of the above challenges and problems arising in the state of the art, improved methods and apparatus for quality control of electrochemical energy storage devices are sought.

[0012] According to a first aspect of the present disclosure, a method for detecting defects in a conductive test sample is provided. The method includes providing an eddy current sensor comprising an induction coil and a sensing coil, providing at least one thermal camera, generating an eddy current in the test sample using the induction coil of the eddy current sensor, detecting a variation in the eddy current in the test sample using the sensing coil of the eddy current sensor, detecting at least one thermal image of the test sample using the at least one thermal camera, and determining at least one quality parameter of the test sample based on the variation in the eddy current and the at least one thermal image.

[0013] According to a second aspect of the present disclosure, a method for manufacturing an electrochemical energy storage device is provided. The method includes performing at least one manufacturing process to produce an element of the electrochemical storage device, the at least one manufacturing process being controlled based on at least one process parameter, determining at least one quality parameter of the element using the method according to the first aspect, and adjusting the at least one process parameter based on the at least one quality parameter according to a predetermined process model.

[0014] According to a third aspect of the present disclosure, a sensor device for detection of defects in a conductive test sample is provided. The sensor device includes at least one eddy current sensor comprising an induction coil and a sensing coil, wherein the induction coil is configured for generating an eddy current in the test sample, and the sensing coil is configured to detect a variation in the eddy current, at least one thermal camera configured to detect at least one thermal image of the electrochemical energy storage device, and a controller configured to determine at least one quality parameter based on the variation in the eddy current and the at least one thermal image. According to a fourth aspect of the present disclosure, a system for manufacturing an electrode for an electrochemical energy storage device is provided. The system includes a slurry mixing apparatus configured for mixing a slurry of an electrode active material according to a slurry recipe, an electrode deposition apparatus configured to deposit at least one layer of the electrode active material onto a foil, an electrode drying apparatus configured to dry the deposited electrode, an electrode calendering apparatus configured for compacting the deposited electrode, and an assembly apparatus configured for assembling deposited electrodes into a housing to form the electrochemical energy storage device. The system further includes at least one sensor device according to the third aspect positioned in, between or after at least one of the electrode deposition apparatus, the electrode drying apparatus, the electrode calendering apparatus and the assembly apparatus, the at least one sensor device being configured to detect a variation in the eddy current and at least one thermal image. The system further includes a system controller configured to control the slurry mixing apparatus, the electrode deposition apparatus, the electrode drying apparatus, the electrode calendering apparatus and the assembly apparatus, wherein the system controller is further configured to determine the at least one quality parameter of at least one of the electrode and the housing based on the variation in the eddy current and the at least one thermal image.

[0015] Aspects of the present disclosure provide improved detection of surface-level and subsurfacelevel defects in electrochemical energy storage devices, particularly in electrodes and housings of the electrochemical energy storage devices. In particular, the methods of quality control, sensor devices and systems of the present disclosure are capable of non-destructive and noncontact detection of defects in real time, allowing for in-situ quality control, and further allowing for process parameters of upstream processes to be adjusted based on a level of quality detected by the quality control system. By controlling the manufacturing processes in a closed- loop fashion, the amount of scrap material, scrap electrodes and / or defective devices may be reduced and the quality and safety of the finished devices is improved.

[0016] Those skilled in the art will recognise additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The components in the figures are not necessarily to scale, instead emphasis is being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts. In the drawings:

[0019] Fig. 1 A illustrates an exemplary eddy current sensor device;

[0020] Fig. IB illustrates an exemplary thermography sensor device;

[0021] Fig. 2 illustrates a sensor device for detecting defects in a conductive test sample according to embodiments of the present disclosure;

[0022] Fig. 3 illustrates a flow chart of a method of detecting defects in a conductive test sample according to embodiments of the present disclosure;

[0023] Fig. 4 illustrate a sensor device for detecting defects in an electrochemical energy storage device according to embodiments of the present disclosure;

[0024] Figs. 5A-5B illustrate a sensor device for detecting an array of quality parameters according to embodiments of the present disclosure;

[0025] Figs. 6A-6B illustrate a sensor device for detecting an array of quality parameters according to embodiments of the present disclosure; and

[0026] Fig. 7 illustrates a system for manufacturing an electrochemical energy storage device according to embodiments of the present disclosure. DETAILED DESCRIPTION

[0027] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in each figure. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It is intended that the present disclosure includes such modifications and variations.

[0028] Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment applies to a corresponding part or aspect in another embodiment as well.

[0029] In seeking improvements to sensors, systems and methods for improved quality control and defect detection, the inventors studied the various non-destructive and non-contact sensing methods and investigated their application to detecting defects in elements of electrochemical energy storage devices. Particularly, methods which allow for the detection of defects in-situ were desirable so that further technical problems in the art could be overcome. Two methods which appeared to be particularly promising were the principles of eddy current sensing and thermography sensing.

[0030] Firstly, the fundamental principle of eddy current sensing will be described. An eddy current sensing device 100 is exemplarily shown in Fig. 1A. Eddy current sensing involves providing an induction coil 110 with an alternating current near the test sample S. By providing alternating current in the induction coil 110, a primary magnetic field FPis generated which induces an eddy current E in the test sample S. In turn, a secondary magnetic field Fsis generated by the eddy current E. Further provided is a sensing coil 120 which allows for variations in these eddy currents E to be measured. The variations in the eddy currents E within the test sample S cause variations in the secondary magnetic field Fsand, in turn, variations in the primary magnetic field FP, which may be sensed by the sending coil 120 for determining at least one of a variation in phase and a variation in magnitude. The eddy current sending device 100 may further include a controller 130 for generating a signal corresponding to a quality parameter Q. The controller 130 may include a controllable alternating current power source 131 for providing alternating current to the induction coil 110, an optional signal filtering element 132 for filtering the signal sensed by the sensing coil 120, and a processing element 133 for processing the signal sensed by the sensing coil 120 and generating the quality parameter Q.

[0031] Eddy currents E generated within the test sample S can be affected by a defect D located within the test sample S. In the case where the test sample S was uniform and free from defects, the variations in the eddy currents E generated in the test sample S would be minimal. However, the presence of a defect D would affect the eddy currents E in the test sample S, causing the eddy currents E to vary in phase and / or magnitude. Eddy current sensing is sensitive enough to detect defects such as cracks, corrosion, impurities, delamination, voids or surface pitting. Accordingly, eddy current sensing provides a non-destructive, non-contact testing method that offers several advantages for inspecting and evaluating the integrity of conductive materials and components.

[0032] Eddy current sensing also has the advantage of being a rapid inspection method, allowing for quick and efficient assessment of large areas or components. It follows that eddy current sensing is suitable for in-situ, high-speed production and quality control processes. Further, eddy current sensing can be automated, allowing for high-throughput inspection processes in industrial settings, ensuring a consistent and reliable assessment of components.

[0033] One downside to the implementation of eddy current sensing for testing electrical components is that the induction coil induces energy and heat into the test sample. A further downside of eddy current sensing is that the detection depth at which defects can be reliably detected is limited to surface-level or near surface-level defects. Although the induction of heat and energy are often undesirable for electrical systems, the method may be safely and reliably implemented for non-destructive testing of electrodes for electrochemical energy storage devices, as well as other components of the device such as the housing of the device, or the finished device in its entirety.

[0034] Secondly, the fundamental principle of thermography testing will be described. An exemplary thermography sensor device 200 is shown in Fig. IB. Thermography sensing involves using vision systems for sensing and analysing infrared radiation being emitted from a test sample S, which is directly correlated to the temperature of the test sample S. A heat source 220 is provided for generating an elevated temperature in the test sample S so that the test sample S emits infrared radiation. Particularly, the test sample S after being subjected to heating exhibits a thermal profile T. Further provided is a thermal camera 210, particularly an infrared camera, which captures a thermal image or a thermal video of the surface of the test sample S, the thermal image or thermal video being representative of the thermal profile T. The thermal image may then be analysed, for example, using computer vision systems or the like, to indicate the presence of a defect D in the test sample S based on the thermal profile T induced in the test sample S by the heat source 220. In the case where the test sample S is uniform and free from a defect D, the thermal profile T would also be substantially uniform. However, the presence of a surface-level or a subsurface-level defect D affects the thermal profile T in the test sample S, and the variations in the thermal profile T can be observed by the thermal camera 210. The thermography sensing device 200 may further include a controller 230 for generating a signal corresponding to a quality parameter Q. The controller 230 may include a controllable power source 231 for providing current to the heat source 220. Further, the controller 230 may include an optional image filtering element 232 for filtering the signal, particularly the thermal image or thermal video, being acquired by the thermal camera 210, and a processing element 233 for processing the thermal image or thermal video, e.g. using a computer vision algorithm, and generating the quality parameter Q based thereon.

[0035] As with eddy current sensing, thermography sensing also offers a rapid inspection method for quick and efficient inspection of large components, meaning thermography sensing is also suitable for in-situ quality control systems. Typical applications for thermography sensing in the current state of the art include construction, industrial applications and medicine, particularly for ensuring the structural integrity of a wide variety of materials. Thermography sensing has the advantage of a large depth of sensing, easier interpretation of visual results, and further provides qualitative data about the depth and size of defects.

[0036] Further, thermography sensing can be used to assess assemblies of components, particularly completed electrochemical energy storage devices, by providing a heat source to the assembly and analysing the subsequent thermal image of the assembly, regardless of whether the components of the assembly are made of ferromagnetic materials. For example, the position of components within the assembly may cause a distinct thermal profile of the outer housing when a temperature is induced in the assembly, allowing thermography sensing to potentially reveal defects arising in assembly, such as incorrectly positioned components, distribution of electrolyte within the housing, or other quality parameters.

[0037] The inventors discovered synergistic effects in combining the principles of eddy current sensing and thermography testing for non-destructive, non-contact detection of defects and for carrying out quality control methods for electrochemical energy storage devices. Since the induction coil of the eddy current sensor generates heat in the test sample during eddy current sensing, said heat generation may be exploited for thermography sensing without an additional heat source being required. Further, a sensing system which combines both techniques allows for more sensitive detection of defects provided by eddy current sensing, while also acquiring additional quantitative data about the size and depth of said defects provided by thermography sensing. Furthermore, since both techniques may be performed in-situ, not only can the sensing techniques both be used in real-time, but the data generated may be used for closed-loop control of the manufacturing process, where processes or sub-processes can be adjusted in real-time based on quality parameters detected by the combined sensor system.

[0038] Referring now to Fig. 2, a sensor device 300 for detection of defects D in a conductive test sample S is provided. According to an aspect of the present disclosure, the sensor device 300 includes at least one eddy current sensor 100 comprising an induction coil 110 and a sensing coil 120, wherein the induction coil 110 is configured for generating an eddy current in the test sample S and the sensing coil 120 is configured to detect a variation in the eddy current. The sensor device 300 further includes at least one thermal camera 210 configured to detect at least one thermal image of the test sample S. The sensor device 300 further includes a controller 330 configured to determine at least one quality parameter Q based on the variation in the eddy current and the at least one thermal image.

[0039] Further, referring to Fig. 3, a method 400 for detection of defects D in a conductive test sample S is provided. Commencing at start 401, the method 400 includes providing 402 an eddy current sensor 100 comprising an induction coil 110 and a sensing coil 120 and providing 403 at least one thermal camera 210. The method 400 further includes generating 404 an eddy current in the test sample S using the induction coil 110 of the eddy current sensor 100 and detecting 406 a variation in the eddy current in the test sample S using the sensing coil 120 of the eddy current sensor 100. As a result of the generating 404, heat is generated in the test sample S, resulting in a thermal profile T. The method 400 further includes detecting 405 at least one thermal image of the test sample S using the at least one thermal camera 210. The thermal image may be, for example, a representation of the thermal profile T induced in the test sample S during the generating 404. The method 400 further includes determining 409 at least one quality parameter Q, particularly an array of quality parameters [Q], of the test sample S based on the variation in the eddy current and the at least one thermal image. The method 400 concludes at end 411.

[0040] The function of the at least one eddy current sensor 100 in the combined sensor device 300 is similar to the function of a standalone eddy current sensor 100 as described previously with respect to Fig. 1 A. Further, the function of the at least one thermal camera 210 is similar to the function of the thermal camera 210 in the standalone thermography sensor 200 as described previously with respect to Fig. IB. However, in the combined sensor device 300, a separate heat source 220 as present in the standalone thermography sensor 200 is no longer required, as the induction coil 110 of the eddy current sensor 100 provides not only the generation of the eddy current in the test sample S, but also generates the heat in the test sample S, giving the test sample S a thermal profile T so that thermography sensing can be performed using the thermal camera 210.

[0041] The sensor device 300 is configured for determining at least one quality parameter Q based on the variation in the eddy current and the at least one thermal image. The variation in the eddy current generated in the test sample S may be, for example, a change in inductance, a change in ohmic resistance, a change in impedance or a change in phase angle. Optionally, the variation in the eddy current is determined by detecting a variation between the signal sensed by the sensing coil 120 and an expected signal based on a predetermined model. The thermal image, on the other hand, may be a single thermal image indicating the thermal profile T of the test sample S at an instantaneous point in time, or may include a plurality of thermal images taken at different times, indicating the rate of change of the thermal profile T. Particularly, the thermal image may include a thermal video, i.e. a stream of thermal images detected at a predetermined frame rate.

[0042] According to an embodiment, which may be combined with other aspects and embodiments described herein, the sensor device 330 is configured for quality control of an electrochemical energy storage device, and the test sample S comprises an element of the electrochemical energy storage device. Particularly, the test sample S includes at least one of the group comprising an electrode of the electrochemical energy storage device, and a housing of the electrochemical energy storage device.

[0043] By using combined eddy current sensing and thermography sensing according to the present disclosure on an electrode of an electrochemical energy storage device, quality parameters of the electrode may be measured quickly and preferably in-situ with the manufacturing process of said electrode. According to an embodiment, which may be combined with aspects and embodiments described herein, the test sample S is an electrode of an electrochemical energy storage device, the electrode comprising a substrate coated with at least one layer of coated electrode material, and the at least one quality parameter indicates a level of quality of the at least one layer.

[0044] Advantageously, since the combined sensor device 330 is both non-contact and non-destructive, the sensor device 330 may be used for testing an electrode at any stage in the electrode manufacturing process after at least one layer of electrode active material is deposited. For example, the sensor device 330 may be positioned after the coating process such that one or more quality parameters of the wet electrode are determined, may be positioned after the drying process such that one or more quality parameters of the dry electrode are determined, or may be positioned after the calendering process such that one or more quality parameters of the calendered electrode are determined.

[0045] In the case where the test sample S is a wet electrode, the sensor device 330 may be configured to determine one or more quality parameters of the wet deposited layers of electrode active material. The at least one quality parameter may include a density and / or distribution of coated electrode material in the wet deposited layers, or may include the presence of inclusions in the at least one layer, such as impurities or particles of powder material. Such quality parameters may indicate an incorrectly mixed slurry which was prepared in the slurry mixing process. Further, the at least one quality parameter may include a thickness and / or thickness distribution of the at least one layer, which may indicate quality issues arising in the coating process and / or the slurry mixing process.

[0046] In the case where the test sample S is a dry electrode or a calendered electrode, the sensor device 330 may be configured to determine one or more quality parameters of the dry and / or compressed layers of electrode active material. The at least one quality parameter may include the presence of a variety of defects in the layers of electrode active material, such as surfacelevel or subsurface-level cracks, voids, pinholes or delaminations. Further, the at least one quality parameter may include a level of adhesion between the layers of electrode active material and the substrate upon which the electrode active material is deposited. Such quality parameters may indicate quality issues arising in the coating process or the drying process.

[0047] In both cases, the defects associated with the quality parameters being determined may be evident from the variation in the eddy current sensed by the sensing coil 120 of the eddy current sensing device 100, may be evident from the thermal image captured by the thermal camera 210, or may be evident from both the variation in the eddy current and the thermal image. For example, the variations in the eddy current detected by the sensor device 300 may indicate an electrical performance defect in the electrode such as resistance or impedance, which cannot be detected by the thermography sensing. On the other hand, the thermography sensing may indicate defects deeper within the layers of electrode active material, such as voids or adhesion defects. Further, both methods may detect the same defects, such as cracks or pinholes at a surface level of the layers of electrode active material. By combining both eddy current sensing and thermography sensing in the same sensor device 300, a broader range of defects and quality parameters may be detected during quality control of the electrode. The combined sensor device 300 may alternatively be used on the housing of an electrochemical energy storage device, as exemplarily shown in Fig. 4. As shown, a plurality of electrochemical energy storage devices may be provided on an assembly line, and may optionally be moving in the transport direction x. The illustrated electrochemical energy storage devices may be fully assembled devices, or partially assembled devices. According to an embodiment, which may be combined with other aspects and embodiments described herein, the test sample S is a housing of an electrochemical energy storage device, and the at least one quality parameter indicates a level of quality of the housing and / or the electrochemical energy storage device. As exemplarily shown in Fig. 4, the eddy current sensor 100 is arranged at a top region of the housing of the electrochemical energy storage device, particularly at a top sealing region of the housing, and the thermal camera 210 is arranged at a front position so as to detect a thermal image, particularly a thermal profile T, of the housing based on the heat generated by the eddy current sensor 100. However, the present disclosure is not limited thereto, and the eddy current sensor 100 and / or the thermal camera 210 may be arranged in other positions. For example, as exemplarily shown, the thermal camera 210, or an additional thermal camera 210, may alternatively be arranged above the housing.

[0048] Similarly to the above discussion with respect to using the sensor device 300 on an electrode, one or more quality parameters of the housing may be determined. Particularly, the quality parameter may include the presence of a defect in the housing, such as a surface-level or subsurface-level crack in the housing, or may indicate a level of quality of the material of the housing. The quality parameter may further include quality parameters relating to one or more joins, such as welded portions or glued portions, indicating the quality of the joins and the quality of sealing of the housing. The quality parameter may further include a level of thermal performance of the housing, such as a rate of thermal transfer indicated by the rate of cooling of the housing. Advantageously, however, in the case of the test sample S being a housing of an electrochemical energy storage device, the sensor device 330 is further capable of determining one or more quality parameters of the electrochemical energy storage device which is housed within the housing. By carrying out additional thermography sensing using the thermal camera 210, the thermal profile T of the housing may further indicate various quality parameters of components within the housing, such as the relative positioning of the components within, including the electrodes and / or electrolyte within the housing. The combined sensing may be carried out on the housing of either a partially assembled electrochemical energy storage device or a fully assembled electrochemical energy storage device. For example, the combined sensing may be carried out on the housing of a partially assembled electrochemical energy storage device which has undergone an assembly process to assemble the electrodes within the housing and to seal the housing by welding, but prior to being filled with electrolyte. Alternatively, the same combined sensing may be carried out on the housing of a fully assembled electrochemical energy storage device which has been filled with electrolyte.

[0049] Accordingly, the sensor device 330 may be used so that the eddy current sensing device 100 of the sensor device 300 generates an eddy current in the housing of a fully assembled, or partially assembled, electrochemical energy storage device and detecting variations in the eddy currents generated allowing for defects to be detected in the housing. At the same time, or subsequently, the sensing device 300 generates heat in the housing, which generates a thermal profile T of the housing. Since the components inside, which may be contacting the housing directly or indirectly, e.g. via electrolyte, can sink heat from the housing at various rates, the housing will exhibit a thermal profile on its outside surface which indicates, for example, the positioning of components within the housing. For example, the positioning of the electrodes within the housing may be determined based on the thermal profile T, and possible assembly defects such as deflected or deformed anode or cathode tabs or defective insulation may become apparent. Further, the thermal profile may indicate quality parameters related to the electrolyte filling, such as the distribution / penetration of electrolyte between electrodes within the housing, a filling level of electrolyte, or a thermal mass of the finished electrochemical energy storage device. The thermal profile of the housing, particularly a thermal image of the housing, may be compared to a predetermined thermal image of a housing which is known to be defect-free to determine whether any quality issues or defects have arisen during the assembly process or the electrolyte filling process.

[0050] According to an embodiment, which may be combined with aspects and embodiments described herein, the controller 330 of the sensor device 300 is configured to carry out the methods for detection of defects D in a conductive test sample S according to aspects and embodiments described in the following. The controller 330 may further include a plurality of modules for operating the various components of the sensor device 300.

[0051] Optionally, the controller 330 may include a controllable alternating current power source 131 for providing alternating current to the induction coil 110. For example, the controllable alternating current power source 131 may be controlled to generate a specific strength of eddy current in the test sample S. Alternatively, the controllable alternating current power source 131 may be controlled to generate a specific temperature in the test sample S. Particularly, the controllable alternating current power source 131 may be controlled to generate a specific strength of eddy current in the test sample S according to a first parameter, then be adjusted to a second parameter different from the first parameter to generate a specific temperature in the test sample S. The controllably alternating current power source 131 may provide at least one of a controllable current, a controllable voltage, a controllable frequency or a controllable power.

[0052] The controller 330 may include at least one optional filtering element configured for filtering a signal from the eddy current sensing device 100 or from the thermal camera 210. Particularly, the controller 330 may include an optional signal filtering element 132 for filtering the signal sensed by the sensing coil 120. For example, the signal filtering element 132 may include an analog signal filter such as a bandpass filter or a comb filter, or may include a digital signal filter as part of a digital signal processor. Further, the controller 330 may include an optional image filtering element 232 for filtering the signal, particularly the thermal image or thermal video, being acquired by the thermal camera 210. The image filtering element 232 may include a digital image filter as part of a digital signal processor.

[0053] Accordingly, the method 400 may be modified to include one or more filtering steps. For example, after the detecting 406 of the variations in the eddy current, the method 400 may optionally include a step of signal filtering 407 of the signal obtained from the eddy current sensor 100 in the detecting 406, particularly from the sensing coil 120 of the eddy current sensor 100. Further, after detecting 405 the thermal image, the method 400 may optionally include a step of image filtering 408 the thermal image obtained from the thermal camera 210 in the detecting 405. These optional method steps are illustrated in Fig. 3 with dashed lines to indicate their optionality.

[0054] The controller 330 may further include a processing element 331 configured to determine the at least one quality parameter Q. The processing element 331 acquires at least one signal corresponding to a variation in the eddy current from the sensing coil 120 of the eddy current sensing device 100 and at least one thermal image from the at least one thermal camera 210. Based on the variation in the eddy current and based on the thermal image, the processing element 331 determines the quality parameter Q. Particularly, the processing element 331 may compare the signal sensed by the sensing coil 120 to a predetermined signal sensed from a test sample known to be defect-free. Similarly, the processing element 331 may compare the thermal image acquired by the thermal camera 210 to a predetermined thermal image which was acquired from a test sample known to be defect-free. Accordingly, the processing element 331 can determine the presence of defects based on the respective comparison. The processing element 331 may be further configured to receive a signal and / or data corresponding to the power parameters at which the controllable alternating current power source 131 is operating, and comparing the signal sensed by the sensing coil 120 to the power parameters based on a predetermined model of an expected eddy current signal.

[0055] The controller 330 of the sensor device 300 may be a microprocessor, a programmable logic controller (PLC), or a digital signal processor (DSP). Particularly, the controller 330 may include a processing element, at least one input and at least one output, such that a data processing operation is performed on the at least one input and output to the at least one output. The controller 330 may further include at least one storage means, which may include random access memory (RAM), read-only memory (ROM) and external data storage means such as hard disks, flash storage or network-attached storage, and may further include a network interface for connecting the controller 330 to a data network, in particular a global data network. For example, the controller 330 may be further configured to transmit at least one quality parameter to a central quality control system such that the respective test sample, particularly the respective electrochemical energy storage device may be sorted or binned according to said quality parameter, or such that the respective test sample, particularly the respective electrode, may be scrapped or reworked according to said quality parameter.

[0056] The thermal camera 210 of the sensor device 330 may include any suitable thermal camera known in the current state of the art. Preferably, the thermal camera 210 may include an infrared camera, as industrial infrared cameras are low-cost allowing the possibility of a large number of thermal cameras to be implemented, and are robust so as to be implemented within the various manufacturing processes of electrochemical energy storage devices.

[0057] As exemplarily shown in Fig. 2, the thermal camera 210 may be positioned so as to detect a thermal image of the test sample S substantially in the region where the eddy current sensing device 100 is positioned, that is, substantially in the region where the induction coil 110 generates heat in the test sample S. However, the present disclosure is not limited thereto, and the thermal camera 210 may be positioned to detect a thermal image of the test sample S in a region different to where the eddy current sensing device 100 is positioned. For example, in the case where the test sample S is moving or being transported in a production process, i.e. in-situ acquisition, the thermal camera 210 may be positioned to detect a thermal image of the test sample S substantially downstream from the region where the eddy current sensing device 100 is positioned.

[0058] Preferably, the sensor device 300 is configured to operate in-situ. That is, the eddy current sensor 100, the thermal camera 210 and the controller 330 are configured to operate in-situ. Similarly, the method 400 is configured to be carried out such that the variation in the eddy current is detected in-situ, the at least one thermal image is detected in-situ and the determining of the quality parameter is carried out in-situ. According to an embodiment, which may be combined with aspects and embodiments described herein, the eddy current sensor 100 and the thermal camera 210 are configured for in-situ detection of the variation in the eddy current and the at least one thermal image, respectively. By determining the quality parameter Q in-situ, which is achieved by implementing rapid sensing methods, the quality control can be carried out directly within the production processes of an electrochemical energy storage device.

[0059] In the context of the present disclosure, the terms “in-line” and “in-situ” are used interchangeably, and refer to the arrangement of a sensor in a process. An “in-line” or “in-situ” acquisition of a battery parameter refers to the observation, measurement or estimation of a battery parameter which is integrated directly into the process. This is in contrast to an “online” acquisition, wherein the observation, measurement or estimation of a battery parameter is taken from a separate area adjacent to the process line, and an “at-line” acquisition or “off-line” acquisition, wherein the observation, measurement or estimation of a battery parameter is performed outside of a process line, for example, in a laboratory. The nature of at-line or off-line analyses is such that automatic control based on those parameters is difficult due to the time delay in obtaining the parameter, and requires the parameter to be manually entered back into the system so that requisite adjustments to process parameters can be carried out. On the other hand, in-line / in-situ measurements have the advantage of real-time acquisition of a quality parameter, and automatic control or closed-loop control can be carried out based on said real-time acquisition. Accordingly, in comparison to quality control methods known in the state of the art such as CT scanning, the sensor device 300 of the present disclosure allows for faster acquisition of quality parameters while also allowing for closed-loop control of the respective production processes to react to quality issues, allowing for the reduction in scrap material and defective components / devices.

[0060] In the following, variations and preferred embodiments of the above-described sensor device 300 and method 400 for detecting a defect in a test sample will be described. Particularly, variations related to expanded embodiments for sensing defects in electrodes, particularly for in-situ sensing of defects in continuous foil electrodes being produced in an electrode manufacturing process, will be described.

[0061] Reference will be made to Fig. 5 A, which shows a sensor device 500 configured for determining an array of quality parameters, particularly for in-situ quality control of an electrode E. According to an embodiment, which may be combined with aspects and embodiments described herein, the sensor device 500 is configured for determining an array of quality parameters [Q] in a sensing area 510 defined by a first direction x and a second direction y perpendicular to the first direction x. The at least one eddy current sensor 100 comprises a plurality of eddy current sensors arranged in at least one row in the first direction x and / or at least one column in the second direction y. Optionally, the at least one thermal camera 210 comprises a plurality of thermal cameras arranged in at least one row in the first direction x and / or at least one column in the second direction y. Accordingly, the method 400 may be further modified such that an array of quality parameters [Q] is determined. According to an embodiment, which may be combined with aspects and embodiments described herein, method 400 is modified wherein the electrode E comprises a continuous foil coated with the at least one layer, the electrode E having a transport direction x aligned with a direction in which the electrode E is being transported, and a transverse direction y perpendicular to the transport direction. The at least one eddy current sensor 100 comprises a plurality of eddy current sensors arranged in at least one row in the transverse direction y and / or arranged in at least one column in the transport direction x, and the at least one thermal camera 210 is arranged in the transport direction x at a position downstream of the plurality of eddy current sensors 100. The method 400 further comprises generating 404 a plurality of eddy currents in the electrode using each respective induction coils of the plurality of eddy current sensors, detecting a variation in each respective eddy current in the electrode using each respective sensing coil of the plurality of eddy current sensors, and determining an array of quality parameters [Q] of the electrode based on the respective variations in the plurality of eddy currents and the at least one thermal image.

[0062] According to an embodiment, which may be combined with aspects and embodiments described herein, the method 400 may be further modified such that the at least one thermal camera 210 comprises a plurality of thermal cameras arranged in at least one row in the transverse direction y and / or arranged in at least one column in the transport direction x. The method 400 further comprises detecting 405 a plurality of thermal images from each respective thermal camera, and determining 409 the array of quality parameters [Q] of the electrode based on the respective variations in the plurality of eddy currents and the plurality of thermal images.

[0063] The sensor device 500 according to this embodiment includes an array of eddy current sensing devices 100, and optionally an array of thermal cameras 210, arranged in a geometric pattern across the surface of the electrode E. Each respective one of the plurality of eddy current sensing devices 100 and optionally the plurality of thermal cameras 210 may be connected to a common controller 330, wherein the controller 330 processes the respective signals from each sensor and determines an array of quality parameters [Q], Although the sensor device 500 is exemplarily shown as having an array of sensors over the upper surface of the electrode E, the present disclosure is not limited thereto, and a similar array of sensors may also be provided over the lower surface of the electrode E. By arranging sensor device 500 in such an array of sensors, the precise location of defects in the electrode E can be determined. Further, the sensor device 500 is capable of detecting defects which may arise in a time-based sensing of thermal images detected in the thermography sensing. Further still, the suitability of the sensor device 500 to in-situ quality control of moving electrodes, or electrodes being transported in a production process, is further enhanced.

[0064] Further, reference will be made to Fig. 5B, which shows an array of quality parameters detected by the sensor device 500 of Fig. 5A. A plurality of sensor positions is defined such that an array of sensor positions yl ...yn are arranged in the transverse direction y, and an array of sensor positions xl . . .xn are arranged in the transport direction x. Given the movement of the electrode E in the transport direction, the array of sensor positions in the transport direction x may alternatively be interpreted as time position tl . . .tn. With respect to the transport direction x in which the electrode E is being transported, and the transverse direction y which is perpendicular to the transport direction x and in the width direction of the electrode E, an array of quality parameters [Q] may be determined. Each dot shown in Fig. 5B may represent a single quality parameter Q measured at various points over the electrode. Each respective quality parameter Q may be assigned a position (x, y) at which the parameter was detected.

[0065] Furthermore, the sensor device 500 having an array of eddy current sensing device 100 may be further configured such that the height of each respective eddy current sensing device 100 may be different. In the normal direction z, which is perpendicular to the transport direction x and the transverse direction y, the respective induction coils 110 of each eddy current sensing device 100 may be adjusted in height such that the depth of eddy current generation, and hence depth of heating, may be varied. The resulting eddy current sensing and / or thermography sensing may then be used to determine a depth of a defect in the thickness direction of the electrode E. Accordingly, each single quality parameter Q may be assigned a depth value such that the array of quality parameters [Q] includes an array of single quality parameters Q(x, y, z). Optionally, the height of the respective eddy current sensing devices 100 may be adjusted based on at least one process parameter, such as a thickness of the coating being deposited.

[0066] The capability of sensor device 500 to accurately determine the position of defects in the electrode E allows for later quality control actions to be undertaken, such as identifying which section of the electrode E along its continuous length contains a defect. For example, the defective section of the continuous electrode E can be cut and removed from the remainder of the electrode E which is defect-free, thus avoiding the scrapping of the whole electrode E and reducing scrap and waste.

[0067] Furthermore, if the sensor device 500 includes an array of thermal cameras arranged in the transport direction x, the transport direction x corresponds substantially to time since a specific position on the moving electrode E passed by an eddy current sensing device 100. Therefore, the array of quality parameters [Q] may be further assigned a time at which the respective single quality parameters Q(t) were measured. Such time-based data allows for the detection of defects which may only become apparent based on, for example, a rate of cooling of the electrode E.

[0068] In a preferred embodiment, the plurality of eddy current sensors 100 may be arranged in a row across the electrode E, while the plurality of thermal cameras 210 may be arranged in a column downstream of the row of eddy current sensors 100. Particularly, the sensing area 510 of each one of the thermal cameras 210 can be specified so that a respective thermal image of the entire width of the electrode E can be detected by each thermal camera 210, negating the need for additional thermal cameras 210 in the transverse direction y. According to an embodiment, which may be combined with other embodiments described herein, the plurality of eddy current sensors 100 is arranged in a row in the transverse direction y, and the plurality of thermal cameras 210 is arranged in a column aligned in the transport direction x, wherein each one of the plurality of thermal cameras 210 has a field of view covering at least the width of the electrode E. The preferred arrangement of eddy current sensors 100 and thermal cameras 210 is exemplarily shown in Fig. 5B, where each of the grey dots arranged in the xl row corresponds to an eddy current sensor 100, and each of the black dots arranged in the y3 column corresponds to a thermal camera 210 arranged downstream of the eddy current sensors 100. Such an arrangement offers positional detection of defects, time-based detection of defects and minimises the number of eddy current sensing devices 100 and thermal cameras 210 required to obtain the array of quality parameters [Q] across the whole width of the electrode E.

[0069] Reference will be made to Fig. 6A, which shows a sensor device 600 configured for determining an array of quality parameters [Q], particularly for in-situ quality control of an electrode E. According to an embodiment, which may be combined with aspects and embodiments described herein, the sensor device 600 is configured for determining an array of quality parameters [Q] in a sensing area defined by a first direction and a second direction perpendicular to the first direction, and the sensor device further comprises a scanning unit configured to move the at least one eddy current sensor 100 and the at least one thermal camera 210 in the first direction and / or the second direction.

[0070] Accordingly, the method 400 may be further modified such that an array of quality parameters [Q] is determined. According to an embodiment, which may be combined with aspects and embodiments described herein, method 400 is modified wherein the electrode E comprises a continuous foil coated with the at least one layer, the electrode E having a transport direction x aligned with a direction in which the electrode E is being transported, and a transverse direction y perpendicular to the transport direction. The at least one eddy current sensor 100 and the at least one thermal camera 210 are configured to move in the transverse direction y. The method 400 further includes scanning 410 the at least one eddy current sensor 100 and the at least one thermal camera 210 in a plurality of scanning positions in the transvers direction y, generating 404 an eddy current in the electrode at each respective scanning position, detecting 406 a variation in the eddy current at each respective scanning position, detecting a thermal image of the electrode at each respective scanning position, and determining an array of quality parameters [Q] of the electrode based on the respective variations in the eddy currents and the respective thermal images at each respective scanning position. The modified method 400, including the additional scanning step, is exemplarily shown in Fig. 3 with the optional scanning step 410 according to the present extended embodiment shown in dashed lines.

[0071] In the embodiment exemplarily shown in Fig. 6A, the sensor device 600 exemplarily includes a single eddy current sensor 100 and a single thermal camera 210. The combined sensor device 600 is mounted on a scanning unit 620 which is configured to scan the sensor device 600 across the electrode E, particularly in a scanning direction which is aligned in the transverse direction y. As the sensor device 600 is scanned across the width of the electrode E, an eddy current measurement can be acquired and a thermal image can be acquired, and the controller 330 may determine a quality parameter Q at each respective scanning position to determine an array of quality parameters [Q],

[0072] The scanning of the sensor device 600 across the electrode E may be performed when transport of the electrode E is stopped, obtaining an array of quality parameters [Q] similar to the array as exemplarily shown in Fig. 5B. Alternatively, the scanning of the sensor device 600 may be performed when the electrode E is being transported, obtaining an array of quality parameters [Q] as exemplarily shown in Fig. 6B. Regardless of which scanning method is used, the sensor device 600 is capable of obtaining an array of quality parameters [Q] across the whole width of the electrode E, and is consequently capable of detecting defects across the whole width of the electrode E, using only a single eddy current sensor 100 and a single thermal camera 210. Furthermore, the sensing device 600 may be adjustable or configurable to perform quality control on electrodes of varying width, depending on the process which is currently being performed.

[0073] As exemplarily shown in Fig. 6A, the sensor device 600 includes a single eddy current sensor 100 and a single thermal camera 210 attached to a single scanning unit 620. However, the present disclosure is not limited thereto, and the sensor device 600 may include any number of eddy current sensors 100 or thermal cameras 210 mounted to a single scanning unit 620, or may alternatively include multiple scanning units 620 each including at least one eddy current sensor 100 and at least one thermal camera 210. For example, in dual-sided coating operations where the electrode E is coated on both sides with electrode active material, the sensor device 600 may include an upper scanning unit 620 configured for scanning an upper eddy current sensor 100 and an upper thermal camera 210 over the upper surface of the electrode E, and further include a lower scanning unit 620 configured for scanning a lower eddy current sensor 100 and a lower thermal camera 210 over the lower surface of the electrode E.

[0074] Reference will now be made to Fig. 7, which shows a schematic flow chart of a system for manufacturing an electrochemical energy storage device. According to a further aspect of the present disclosure, a system 700 for manufacturing an electrode for an electrochemical energy storage device is provided. The system 700 includes a slurry mixing apparatus 710 configured for mixing a slurry of electrode active material according to a slurry mixing recipe. The system 700 further includes an electrode deposition apparatus 720 configured to deposit at least one layer of the electrode active material onto a foil, an electrode drying apparatus 730 configured to dry the deposited electrode, and an electrode calendering apparatus 740 configured for compacting the deposited electrode. Further, the system 700 includes an assembly apparatus 750 configured for assembling the deposited electrodes into a housing to form the electrochemical energy storage device. Further, the system 700 includes at least one sensor device 770 according to any of the aspects and embodiments disclosed herein. The at least one sensor device 770 is positioned in, between or after at least one of the electrode deposition apparatus 720, the electrode drying apparatus 730, the electrode calendering apparatus 740 and the assembly apparatus 750. The at least one sensor device 770 is configured to detect a variation in the eddy current and at least one thermal image of a test sample, particularly wherein the test sample is an electrode or a housing of the electrochemical energy storage device. The system 700 further includes a system control 760 configured to control the slurry mixing apparatus 710, the electrode deposition apparatus 720, the electrode drying apparatus 730, the electrode calendering apparatus 740 and the assembly apparatus 750, preferably wherein the system controller is configured to determine the at least one quality parameter of at least one of the electrode and the housing based on the variation in the eddy current and the at least one thermal image.

[0075] Each of the sub-processes of system 700 may be controlled by the system controller 760 or may alternatively include a respective controller for controlling each sub-process. For example, as exemplarily shown in Fig. 7, the slurry mixing apparatus 710 may include a mixing controller 711 configured for controlling the slurry mixing apparatus 710 according to at least one slurry mixing process parameter. Further, the electrode deposition apparatus 720 may include a deposition controller 721 configured for controlling the electrode deposition apparatus 720 according to at least one deposition process parameter. Similarly, electrode drying apparatus 730, electrode calendering apparatus 740 and assembly apparatus 750 may each include drying controller 731, calendering controller 741 and assembly controller 751, respectively, each controller being configured for controlling the respective sub-process according to at least one process parameter. As shown in Fig. 7, the respective sensor devices 770 are provided in-line with the various processes of system 700. Each one of the sensor devices 770, comprising its own controller, may be configured to determine the quality parameter Q at each sub-process. For example, a sensor device 770 positioned in or after the electrode deposition apparatus 720 may determine at least one deposition quality parameter Qdepo, a sensor device positioned in or after the electrode drying apparatus 730 may determine at least one drying quality parameter Qdry, a sensor device positioned in or after the electrode calendering apparatus 740 may determine at least one calendering quality parameter Qcal, and a sensor device positioned in or after the assembly apparatus 750 may determine at least one drying quality parameter Qasm. Each of the quality parameters may be provided to the system controller 760 as a plurality of quality parameters QALL, SO that the system controller 760 can adjust the process parameters of the various sub-processes based on the predetermined model 761.

[0076] Alternatively, the system controller 760 may include one or more elements which implement the functions of the controller of each sensor device 770. For example, the controller of each sensor device 770 may be integrated into the system controller 760 such that quality parameters Q are determined by the system controller 760. According to an embodiment, which may be combined with aspects or embodiments described herein, the system controller is further configured to carry out any of the methods described herein.

[0077] The system controller 760 of system 700 may be a microprocessor, a programmable logic controller (PLC), or a digital signal processor (DSP). Particularly, the system controller 760 may include a processing element, at least one input and at least one output, such that a data processing operation is performed on the at least one input and output to the at least one output. The system controller 760 may further include at least one storage means, which may include random access memory (RAM), read-only memory (ROM) and external data storage means such as hard disks, flash storage or network-attached storage, and may further include a network interface for connecting the system controller 760 to a data network, in particular a global data network. For example, the system controller 760 may be further configured to transmit at least one quality parameter Q to a central quality control system such that the respective electrochemical energy storage device, or batch thereof, may be sorted or binned according to said quality parameter Q.

[0078] Aspects of the present disclosure provide methods of controlling the electrochemical energy storage device manufacturing process, and in particular, the electrode manufacturing process. In particular, the system controller 760 may be provided and configured to control the manufacturing process, particularly the electrode manufacturing process and subsequent assembly processes, according to an overarching closed-loop control regime. The quality parameters Q acquired in the various sub-processes may be used as feed-back or feed-forward signals and provided to a previous sub-process or a subsequent sub-process, respectively, so that the process parameters of the respective previous / subsequent sub-process can be adjusted based on a predetermined model of said process. Alternatively, as exemplarily illustrated in Fig. 7, the system controller 760 may be configured to adjust the process parameters of each subprocess based on a system-wide predetermined model 761.

[0079] The predetermined model 761 may include a plurality of correlations between the quality parameters Q determined at or between each of the sub-processes by in-line sensor devices 770 and the process parameters of each of the sub-processes. Using the predetermined model 761, at least one adjusted process parameter AP may be generated based on at least one of the quality parameters Q. Particularly, a set of adjusted process parameters APALL is generated, comprising one or more adjusted process parameters for the slurry mixing process APmix, the deposition process APdepo, the drying process APdry, the calendering process APC£dand the assembly processes APasmso that the process parameters within each sub-process can be updated with the adjusted process parameters. Accordingly, the system 700 operates in a closed-loop fashion. In the context of the present disclosure, the term “process parameter” refers to a parameter which defines an aspect of the process to be carried out. The process parameter may constitute a process state, e.g. an on / off condition, but typically constitutes a variable state which may be adjusted to achieve a desired process outcome. For a certain process, one or more process parameters may be initialised with a predefined set of values and may be automatically adjusted, updated or modified by a control method. For example, a process parameter may include an actuator on / off state, an actuator speed, a temperature, a pressure, or any other parameter which is used to control an aspect of a process.

[0080] Preferably, the predetermined model 761 includes a predetermined empirical model. Empirical data can be generated through operation of the electrochemical energy storage device manufacturing system, or particularly the electrode manufacturing system, or through prior knowledge of similar manufacturing systems implemented previously. Alternatively, the predetermined model 761 may include a number of correlations obtained from simulation, estimation, extrapolation or calculation. For example, for at least an initial “training” period of operating the manufacturing process, there may be insufficient empirical data on hand to build a comprehensive model. The predetermined model 761 may be operated based on a simulated, estimated, extrapolated or calculated model for a period of time while collecting empirical data, until sufficient data has been generated so that the predetermined model 761 may be replaced with an empirical model. As a further alternative, the predetermined model 761 may include a machine learning model which, when presented with an initial set of training data, is adapted to automatically improve the correlations during ongoing operation of the electrode manufacturing system.

[0081] The closed-loop control systems of the aspects and embodiments described herein allow for the acquisition of quality parameters Q of a wet deposited layer of electrode active material, a dry deposited layer of electrode active material, a calendered electrode, a housing of the electrochemical energy storage device, a partially-assembled electrochemical energy storage device and / or a fully-assembled electrochemical energy storage device to be obtained quickly and reliably. Further, the closed-loop control systems allow for variations in raw material quality, mixed slurry quality, deposition quality, housing material quality, housing welding quality, component assembly quality and other quality parameters to be detected and the respective processes to be adjusted quickly and reliably, allowing for the reduction in scrap material and a reduction in defective devices.

[0082] In view of the above, the present disclosure provides further methods with respect to system 700. According to a further aspect, a method for manufacturing an electrochemical energy storage device is provided, the method comprising performing at least one manufacturing process to produce an element of the electrochemical energy storage device, the at least one manufacturing process being controlled based on at least one process parameter, determining at least one quality parameter of the element using methods according to the aspects and embodiments described herein, and adjusting the at least one process parameter based on the at least one quality parameter according to a predetermined process model.

[0083] According to an embodiment, which may be combined with aspects and embodiments described herein, the element of the electrochemical energy storage device is an electrode comprising at least one layer of coated electrode material, the at least one manufacturing process is at least one of the group comprising a slurry coating process, an electrode drying process, and an electrode calendering process, the at least one eddy current sensor and the at least one thermal camera are provided at a position after the at least one manufacturing process, and the at least one quality parameter Q indicates a level of quality of the at least one layer. Such an embodiment allows for closed-loop control of the various sub-processes involved with electrode manufacturing to ensure high quality of the manufactured electrode, and also for reducing scrap and waste of defective electrodes by quickly reacting to quality issues and adjusting the process parameters accordingly.

[0084] According to an embodiment, which may be combined with aspects and embodiments described herein, the element of the electrochemical energy storage device is a housing of a completed electrochemical energy storage device, the at least one manufacturing process is an assembly process wherein the electrochemical energy storage device is assembled within the housing, and the at least one quality parameter indicates a level of quality of the housing and / or electrochemical energy storage device. Such an embodiment allows for closed-loop control of the various sub-processes involved with the housing of the electrochemical energy storage device, such as a welding process or sealing process, and also control of the various subprocesses involved with assembly or partial assembly of the electrochemical energy storage device, such as electrode positioning within the housing and electrolyte filling. By reacting to quality issues in a closed-loop fashion, the number of defective devices and scrap rates may be reduced.

[0085] Further, certain sub-processes in system 700 include operations which generate heat within the electrode as the sub-process is carried out. For example, the electrode drying apparatus 730 includes a heat source for drying the deposited layer of electrode active material using heat so as to evaporate the solvents contained within the deposited layer. Similarly, the electrode calendering apparatus 740 includes heated rollers for compressing the deposited layer of electrode active material. Accordingly, thermography sensing as described in the present disclosure may be carried out after or during the electrode drying process or the electrode calendering process, i.e. in or after the electrode drying apparatus 730 or the electrode calendering apparatus 740, based on the heat generated by said process and the corresponding thermal profile of the electrode. Accordingly, fewer or no eddy current sensors 100 may be necessary at this stage of the electrode manufacturing process for generating heat for thermography sensing, and the sensor device 770 may be configured instead only to carry out thermography sensing on the electrode so that defects and quality issues can be detected.

[0086] Although various exemplary embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that various changes and modifications can be made which will achieve some of the advantages of the invention without departing from the spirit and scope of the invention. It will be obvious to those reasonably skilled in the art that other components performing the same functions may be suitably substituted. It should be mentioned that features explained with reference to a specific figure may be combined with features of other figures, even in those cases in which this has not explicitly been mentioned.

[0087] Spatially relative terms such as “under”, “below”, “lower”, “over”, “upper” and the like are used for ease of description to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as “first”, “second”, and the like, are also used to describe various elements, regions, sections, etc. and are also not intended to be limiting. Like terms refer to like elements throughout the description.

[0088] As used herein, the terms “having”, “containing”, “including”, “comprising” and the like are open ended terms that indicate the presence of stated elements or features, but do not preclude additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.

[0089] With the above range of variations and applications in mind, it should be understood that the present invention is not limited by the foregoing description, nor is it limited by the accompanying drawings. Instead, the present invention is limited only by the following claims and their legal equivalents. Reference numbers

[0090] 100 Eddy current sensing device 409 Determining the at least one

[0091] 110 Induction coil quality parameter

[0092] 120 Sensing coil 410 Scanning the sensor device

[0093] 130 Controller 411 Method end

[0094] 131 AC power source 500 Sensor device, array type

[0095] 132 Signal filtering element 510 , 610 Sensing area

[0096] 133 Processing element 600 Sensor device, scanning type

[0097] 200 Thermography sensing device 620 Scanning unit

[0098] 210 Thermal camera 700 System for manufacturing an

[0099] 220 Heat source electrochemical energy storage

[0100] 230 Controller device

[0101] 231 Controllable power source 710 Slurry mixing apparatus

[0102] 232 Image filtering element 711 Mixing controller

[0103] 233 Processing element 720 Electrode deposition apparatus

[0104] 300 Sensor device 721 Deposition controller

[0105] 330 Controller 730 Electrode drying apparatus

[0106] 331 Processing element 731 Drying controller

[0107] 400 Method for detecting defects in 740 Electrode calendering apparatus a conductive test sample 741 Calendering controller

[0108] 401 Method start 750 Assembly apparatus

[0109] 402 Providing at least one eddy 751 Assembly controller current sensing device 760 System controller

[0110] 403 Providing at least one thermal 761 Predetermined model camera 770 In-line sensor device

[0111] 404 Generating an eddy current in C Eddy currents the test sample D Defect

[0112] 405 Detecting a thermal image E Electrode

[0113] 406 Detecting a variation in the FPPrimary magnetic field eddy current FsSecondary magnetic field

[0114] 407 Filtering the signal from the Q Quality parameter sensing coil [Q] Array of quality parameters

[0115] 408 Filtering the thermal image AP Adjusted process parameter

[0116] S Test sample T Thermal profile t Time x Transport direction y Transverse direction z Depth direction

Claims

Claims1. A method (400) for detecting defects in a conductive test sample (S), the method (400) comprising: providing (402) an eddy current sensor (100) comprising an induction coil (110) and a sensing coil (120); providing (403) at least one thermal camera (210); generating (404) an eddy current in the test sample (S) using the induction coil (110) of the eddy current sensor (100); detecting (406) a variation in the eddy current in the test sample (S) using the sensing coil (120) of the eddy current sensor (100); detecting (405) at least one thermal image of the test sample (S) using the at least one thermal camera (210); and determining (409) at least one quality parameter (Q, [Q]) of the test sample (S) based on the variation in the eddy current and the at least one thermal image.

2. The method (400) according to claim 1, wherein the eddy current sensor (100) and the thermal camera (210) are configured for in-situ detection of the variation in the eddy current and the at least one thermal image, respectively.

3. The method (400) according to any one of claims 1 to 2, wherein the test sample (S) is an electrode (E) of an electrochemical energy storage device, the electrode (E) comprising a substrate coated with at least one layer of coated electrode material, and the at least one quality parameter (Q, [Q]) indicates a level of quality of the at least one layer,preferably wherein the at least one quality parameter (Q, [Q]) comprises at least one of the group consisting of: the presence of a surface-level or subsurface-level crack in the at least one layer; the presence of a surface-level or subsurface-level void or pinhole in the at least one layer; the presence of inclusions in the at least one layer; a level of adhesion between the at least one layer and the substrate; a density and / or distribution of coated electrode material in the at least one layer; and a thickness and / or thickness distribution of the at least one layer.

4. The method (400) according to claims 2 and 3, wherein: the electrode (E) comprises a continuous foil coated with the at least one layer, the electrode (E) having a transport direction (x) aligned with a direction in which the electrode (E) is being transported, and a transverse direction (y) perpendicular to the transport direction (x); the at least one eddy current sensor (100) comprises a plurality of eddy current sensors (100) arranged in at least one row in the transverse direction (y) and / or arranged in at least one column in the transport direction (x); and the at least one thermal camera (210) is arranged in the transport direction (x) at a position downstream of the plurality of eddy current sensors (100), and the method further comprises: generating (404) a plurality of eddy currents in the electrode using each respective induction coils (110) of the plurality of eddy current sensors (100); detecting (406) a variation in each respective eddy current in the electrode using each respective sensing coil (120) of the plurality of eddy current sensors (100); anddetermining (409) an array of quality parameters (Q, [Q]) of the electrode based on the respective variations in the plurality of eddy currents and the at least one thermal image.

5. The method (400) according to claim 4, wherein the at least one thermal camera (210) comprises a plurality of thermal cameras (210) arranged in at least one row in the transverse direction (y) and / or arranged in at least one column in the transport direction (x), and the method further comprises: detecting (405) a plurality of thermal images from each respective thermal camera (210); and determining (409) the array of quality parameters (Q, [Q]) of the electrode based on the respective variations in the plurality of eddy currents and the plurality of thermal images.

6. The method (400) according to claim 5, wherein the plurality of eddy current sensors (100) is arranged in a row in the transverse direction (y); and the plurality of thermal cameras (210) is arranged in a column aligned in the transport direction (x), wherein each one of the plurality of thermal cameras (210) has a field of view covering at least the width of the electrode (E).

7. The method (400) according to claims 2 and 3, wherein the electrode (E) comprises a continuous foil coated with the at least one layer, the electrode (E) having a transport direction (x) aligned with a direction in which the electrode is being transported, a transverse direction (y) perpendicular to the transport direction (x); andthe at least one eddy current sensor (100) and the at least one thermal camera (210) are configured to move in the transverse direction (y), and the method further comprises: scanning (410) the at least one eddy current sensor (100) and the at least one thermal camera (210) in a plurality of scanning positions in the transverse direction (y); generating (404) an eddy current in the electrode at each respective scanning position; detecting (406) a variation in the eddy current at each respective scanning position; detecting (405) a thermal image of the electrode at each respective scanning position; and determining (409) an array of quality parameters (Q, [Q]) of the electrode based on the respective variations in the eddy currents and the respective thermal images at each respective scanning position.

8. The method (400) according to any one of claims 1 to 2, wherein the test sample (S) is a housing of an electrochemical energy storage device, and the at least one quality parameter (Q, [Q]) indicates a level of quality of the housing and / or the electrochemical energy storage device, preferably wherein the at least one quality parameter (Q, [Q]) comprises at least one of the group consisting of a level of quality of one or more welded portions in the housing; a level of material quality of the housing; the presence of a surface-level or subsurface-level crack in the housing; a level of quality of the assembly of components within the housing; a distribution of electrolyte within the housing; a level of thermal performance of the housing; anda level of thermal mass of the electrochemical energy storage device.

9. A method for manufacturing an electrochemical energy storage device, comprising: performing at least one manufacturing process to produce an element of the electrochemical energy storage device, the at least one manufacturing process being controlled based on at least one process parameter; determining at least one quality parameter (Q, [Q]) of the element using the method according to any one of claims 1 to 8; and adjusting the at least one process parameter based on the at least one quality parameter (Q, [Q]) according to a predetermined process model.

10. The method according to claim 9, wherein the element of the electrochemical energy storage device is an electrode (E) comprising at least one layer of coated electrode material; the at least one manufacturing process is at least one of the group comprising a slurry coating process, an electrode drying process, and an electrode calendering process; the at least one eddy current sensor (100) and the at least one thermal camera (210) are provided at a position after the at least one manufacturing process; and the at least one quality parameter (Q, [Q]) indicates a level of quality of the at least one layer, preferably wherein the at least one quality parameter (Q, [Q]) comprises at least one of the group consisting of: the presence of a surface-level or subsurface-level crack in the at least one layer; the presence of a surface-level or subsurface-level void or pinhole in the at least one layer;the presence of inclusions in the at least one layer; a level of adhesion between the at least one layer and the substrate; a density and / or distribution of coated electrode material in the at least one layer; and a thickness and / or thickness distribution of the at least one layer.

11. The method according to claim 9, wherein the element of the electrochemical energy storage device is a housing of a completed electrochemical energy storage device; the at least one manufacturing process is an assembly process wherein the electrochemical energy storage device is assembled within the housing; and the at least one quality parameter (Q, [Q]) indicates a level of quality of the housing and / or electrochemical energy storage device, preferably wherein the at least one quality parameter (Q, [Q]) comprises at least one of the group consisting of: a level of quality of one or more welded portions in the housing; a level of material quality of the housing; the presence of a surface-level or subsurface-level crack in the housing; a level of quality of the assembly of components within the housing; a distribution of electrolyte within the housing; a level of thermal performance of the housing; and a level of thermal mass of the electrochemical energy storage device.

12. Sensor device (300, 500, 600, 770) for detection of defects in a conductive test sample (S), the sensor device (300, 500, 600, 770) comprising:at least one eddy current sensor (100) comprising an induction coil (110) and a sensing coil (120), wherein the induction coil (110) is configured for generating an eddy current in the test sample (S) and the sensing coil (120) is configured to detect a variation in the eddy current; at least one thermal camera (210) configured to detect at least one thermal image of the test sample (S); and a controller (330) configured to determine at least one quality parameter (Q, [Q]) based on the variation in the eddy current and the at least one thermal image.

13. The sensor device (500, 770) according to claim 12, wherein the sensor device (500, 770) is configured for determining an array of quality parameters ([Q]) in a sensing area defined by a first direction and a second direction perpendicular to the first direction; the at least one eddy current sensor (100) comprises a plurality of eddy current sensors (100) arranged in at least one row in the first direction and / or at least one column in the second direction; and optionally the at least one thermal camera (210) comprises a plurality of thermal cameras (210) arranged in at least one row in the first direction and / or at least one column in the second direction.

14. The sensor device (600, 770) according to claim 12, wherein the sensor device (600, 770) is configured for determining an array of quality parameters ([Q]) in a sensing area defined by a first direction and a second direction perpendicular to the first direction; andthe sensor device (600, 770) further comprises a scanning unit (620) configured to move the at least one eddy current sensor (100) and the at least one thermal camera (210) in the first direction and / or the second direction.

15. The sensor device (300, 500, 600, 770) according to any one of claims 12 to 14, wherein the controller (330) is configured to carry out the method according to any one of claims 1 to 8.

16. The sensor device (300, 500, 600, 770) according to any one of claims 12 to 15, wherein the sensor device (300, 500, 600, 770) is configured for quality control of an electrochemical energy storage device, and the test sample (S) comprises an element of the electrochemical energy storage device, particularly at least one of the group comprising: an electrode of the electrochemical energy storage device; and a housing of the electrochemical energy storage device.

17. System (700) for manufacturing an electrode for an electrochemical energy storage device, the system (700) comprising: a slurry mixing apparatus (710) configured for mixing a slurry of electrode active material according to a slurry mixing recipe; an electrode deposition apparatus (720) configured to deposit at least one layer of the electrode active material onto a foil; an electrode drying apparatus (730) configured to dry the deposited electrode; an electrode calendering apparatus (740) configured for compacting the deposited electrode;an assembly apparatus (750) configured for assembling deposited electrodes into a housing to form the electrochemical energy storage device; at least one sensor device (300, 500, 600, 770) according to any one of claims 12 to 15 positioned in, between or after at least one of the electrode deposition apparatus (720), the electrode drying apparatus (730), the electrode calendering apparatus (740) and the assembly apparatus (750), the at least one sensor device (300, 500, 600, 770) being configured to detect a variation in the eddy current and at least one thermal image; and a system controller (760) configured to control the slurry mixing apparatus (710), the electrode deposition apparatus (720), the electrode drying apparatus (730), the electrode calendering apparatus (740) and the assembly apparatus (750), preferably wherein the system controller (760) is further configured to determine the at least one quality parameter (Q, [Q]) of at least one of the electrode and the housing based on the variation in the eddy current and the at least one thermal image.

18. The system (700) according to claim 17, wherein the system controller (760) is further configured to carry out the method according to any one of claims 1 to 11.

Images