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

Abstract

The present disclosure provides sensor devices and methods for detecting corrosion of an electrode substrate, particularly for water-based electrode coating. According to aspects and embodiments of the present disclosure, a method for quality control of an electrode is provided for determining at least one quality parameter based on a measurement of an amount of hydrogen gas emitted from an electrode using a hydrogen gas sensor. The method may further include measuring an amount of hydrogen gas using a hydrogen gas sensor combined with microwave sensing to determine at least one quality parameter. Systems and methods are further provided for manufacturing an electrode electrochemical energy storage device, particularly an electrode for any electrochemical energy storage device.

Description

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

[0002] TECHNICAL FIELD

[0003] Embodiments of the present disclosure relate to methods for improved quality control of electrodes for electrochemical energy storage devices, as well as systems and methods for manufacturing of said electrodes. Particularly, embodiments of the present disclosure relate to methods for detecting corrosion of a coated substrate using hydrogen gas sensing and optionally microwave sensing, and particularly wherein the respective 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 the use of toxic materials which are detrimental to human health and the environment. Traditional electrode fabrication is based on the use of an organic solvent such as N-Methyl-2-pyrrolidone (NMP) which is mixed with electrode active material precursors to form the slurry which is coated onto the electrode substrate to produce a coated electrode. The coated electrode is then subjected to a drying process to evaporate the organic solvent. Other substances such as per- and poly-fluoroalkyl substances (PF AS).

[0006] However, organic solvents such as NMP are toxic and environmentally hazardous, requiring special handling processes and systems as well as extensive ventilation systems to control its use. NMP solvent and NMP -based slurry mixtures are also sensitive to humidity, requiring a controlled environment for storage. Further, organic solvents require expensive recovery systems to collect and recycle the solvent. Further, substances such as PF AS which are also used in electrode manufacturing, particularly in electrode coating, are beginning to be restricted by governing bodies due to their impact on human health and the environment.

[0007] In view of the problems associated with the use of organic solvents such as NMP, manufacturers of electrochemical energy storage devices are switching from NMP -based coatings to waterbased coatings, seeking benefits in cost reduction and reduced environmental and human impact. However, many challenges have arisen in the implementation of water-based electrode coating.

[0008] One particular challenge is that using water in electrode coatings can cause corrosion of components of the electrode. For example, typical coatings used in electrodes such as nickel manganese cobalt oxide (NMC) or nickel cobalt aluminium (NCA) for cathodes, and lithium titanate oxide (LTO) for anodes, are typically coated onto aluminium substrates as the current collector. Water-based coatings cause excessive corrosion of the aluminium substrate, causing pinholes and other surface defects which affect the adhesion of the coating to the substrate. Although sensing systems such as vision-based and laser-based sensing systems are used in the current state of the art for quality control of electrodes, corrosion on the surface of the aluminium substrate is not detectable with such sensing systems.

[0009] A further challenge arises in that electrochemical energy storage devices, particularly lithium ion batteries, are sensitive to moisture content within components of the device. Extensive drying processes are required to control the water content of the electrodes after coating. Unlike traditional solvent-based coatings which have a low water content, moving to a water-based coating requires extensive monitoring of the water content in the electrode to maintain quality.

[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 thereof, are sought. SUMMARY

[0011] 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 quality control of an electrode for an electrochemical energy storage device is provided. The method includes providing at least one hydrogen gas sensor in at least one of an electrode coating apparatus and an electrode drying apparatus carrying out at least one of coating an electrode in the electrode coating apparatus and drying an electrode in the electrode drying apparatus acquiring a measurement of hydrogen gas being generated during the coating and / or the drying, and determining at least one quality parameter of the electrode based on the measurement of hydrogen gas.

[0013] According to a second aspect of the present disclosure, a method for manufacturing an electrode for an electrochemical energy storage device is provided. The method includes performing at least one manufacturing process to produce the electrode 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 electrode 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 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 electrode active material according to a slurry mixing recipe, an electrode coating apparatus configured to deposit at least one layer of the electrode active material onto a foil, an electrode drying apparatus configured to dry the coated electrode, an electrode calendering apparatus configured for compacting the coated electrode, at least one hydrogen sensor positioned in at least one of the electrode coating apparatus and the electrode drying apparatus, the at least one hydrogen sensor being configured to acquire a measurement of hydrogen gas generated during coating and / or drying of the electrode, and a system controller configured to control the slurry mixing apparatus, the electrode coating apparatus, the electrode drying apparatus and the electrode calendering apparatus, wherein the system controller is further configured to determine at least one quality parameter of the electrode based on the measurement of hydrogen gas.

[0015] Aspects of the present disclosure provide improved detection of corrosion on an electrode substrate when subjected to water-based coating. In particular, the methods of quality control, sensor devices and systems of the present disclosure are capable of non-destructive and noncontact detection of corrosion 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 illustrates a flow chart of a method for quality control of an electrode for an electrochemical energy storage device according to embodiments of the present disclosure; Fig. 2 illustrates a sensor device for quality control of an electrode according to embodiments of the present disclosure;

[0020] Fig. 3 illustrates a system for manufacturing an electrode for an electrochemical energy storage device according to embodiments of the present disclosure;

[0021] Fig. 4 illustrates a secondary drying apparatus according to embodiments of the present disclosure; and

[0022] Fig. 5 illustrates a system for manufacturing an electrode for an electrochemical energy storage device according to embodiments of the present disclosure.

[0023] DETAILED DESCRIPTION

[0024] 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.

[0025] 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.

[0026] 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 electrodes 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. For detecting corrosion which has occurred on the electrode, particularly the current collector of the electrode, either during coating, drying or calendering of the electrode, the inventors found that detecting the presence of hydrogen in the various process apparatus indicated that corrosion has occurred.

[0027] Production of the electrode active materials, in particular for lithium-ion batteries, generally produce lithium hydroxide impurities into the slurry after mixing. When new water-based coating methods are used to manufacture coated electrodes, the presence of Li OH impurities in the electrode slurry will lead to corrosion of an aluminium substrate, i.e. the current collector, according to the following chemical reaction:

[0028] 2LiOH + 2A1 + 2H2O 2LiA102+ 3H2$ ... (1)

[0029] The resulting corrosion causes defects to be introduced into the surface of the aluminium substrate, such as pinholes or a surface deposit of lithium aluminate. Such defects develop on the surface of the aluminium substrate to which the layers of electrode active material are coated, and quality problems arise with respect to layer adhesion.

[0030] The above example is provided for the reaction and subsequent corrosion of an aluminium substrate in the presence of lithium hydroxide impurities. However, the present disclosure is not limited thereto, and the aspects and embodiments of the present disclosure are also applicable to other cell chemistries and other electrode substrate materials known in the art.

[0031] When new water-based coating methods are used, although the pH of the slurry can be adjusted by introducing additives during the slurry mixing process, the pH of the slurry varies significantly as the water evaporates. This variation in pH is challenging to control using openloop control methods without in-situ sensing, and introduces significant problems with corrosion of the aluminium substrate. Further, the elevated temperatures at which the subsequent drying and calendering processes are carried out exacerbates the problem. Known methods exist for at least mitigating the corrosion of the aluminium substrate, for example, by controlling various parameters of the slurry mixing process and the drying process. One option is to control the drying process so as to evaporate the water from the electrode as quickly as possible. However, there are limitations to drying temperature and drying power, and other quality problems may arise with high-power or high-speed drying such as cracking of the electrode active material layer.

[0032] Other options include introducing additives into the mixed slurry to control the pH of the mixed slurry, such as including a pH buffer, or introducing additives to form a protective film on the current collector prior to or during coating. For example, a pH buffer such as ammonium sulfate (NH4)SO4or sulfuric acid H2SO4may be introduced to maintain the pH value of the slurry below 10, so that corrosion of the aluminium substrate is mitigated. Alternatively, an additive such as trace amounts of sodium metavanadate NaVO3may be introduced into the mixed slurry to form a protective barrier on the aluminium current collector, such that the vanadium content of the additive bonds to the aluminium to form a protective alloy layer to mitigate corrosion.

[0033] Another option includes adjusting the slurry mixing recipe to compensate for the corrosion. Parameters such as a solid content of the water-based slurry mixture may be adjusted, or other parameters such as the mixing time or storage time may be adjusted.

[0034] However, in all of the above corrosion mitigation methods, the adjustments and / or introduction of additives is merely carried out only in reaction to a defective batch of electrodes which may have been subjected to off-line quality control in a laboratory setting. Without a means to acquire a level of corrosion in real time, using an in-situ acquisition means, the above mitigating methods cannot be carried out in real-time, resulting in potentially whole batches of coated electrodes being scrapped due to inadequate corrosion mitigation.

[0035] In the present disclosure, detecting the presence and / or amount of hydrogen using at least one hydrogen gas sensor provided within the electrode manufacturing system allows for a level of corrosion which has occurred on the surface of the aluminium substrate to be determined. As shown in equation (1) above, the corrosion caused by the lithium hydroxide impurities generates hydrogen, which is emitted from the electrode as corrosion occurs and as the water in the coated electrode evaporates. Further, the detection of hydrogen can be carried out as a real-time, in- situ acquisition using conventional hydrogen gas sensors, so that closed-loop control of the electrode manufacturing process can be implemented in a cost-effective manner. Further, the above-mentioned corrosion mitigation methods can be implemented in real-time, achieving a significant reduction in scrap electrodes and improving the quality of the coated electrodes.

[0036] Reference will now be made to Fig. 1, which shows a flow chart of a method 400 for quality control according to aspects and embodiments of the present disclosure. Sections of the flow chart marked in dashed lines are marked as optional elements. The method 400 for quality control of an electrode for an electrochemical energy storage device commences at start 401 and includes providing 402 at least one hydrogen gas sensor in at least one of an electrode coating apparatus and an electrode drying apparatus, carrying out at least one of coating 404 an electrode in the electrode coating apparatus and drying 405 an electrode in the electrode drying apparatus, acquiring 406 a measurement of hydrogen gas being generated during the coating 404 and / or the drying 405, and determining 409 at least one quality parameter Q of the electrode based on the measurement of hydrogen gas. The method concludes at end 410.

[0037] Preferably, the at least one quality parameter Q corresponds to a level of corrosion which has occurred on the electrode, particularly on the current collector of the electrode, such as an aluminium foil. According to an embodiment, which may be combined with aspects and embodiments described herein, the electrode comprises a continuous foil coated with at least one layer of electrode active material, and the at least one quality parameter Q corresponds to a level of corrosion of the foil. Particularly, the at least one quality parameter Q corresponds to a level of corrosion on the surface of the foil onto which the at least one layer of electrode active material is coated. With conventional vision-based or laser-based sensing techniques, the detection of such corrosion is not possible since the electrode active material is coated thereon. Similarly, in-situ detection of corrosion is difficult, particularly with continuous electrodes. However, the apparatus and methods of the present disclosure allow such corrosion to be detected by sensing the amount of hydrogen emitted by the coated electrode, and further allows said detection in-situ with continuous electrodes undergoing coating, drying or calendering.

[0038] The at least one hydrogen gas sensor as used in the methods of the present disclosure may include any suitable hydrogen gas sensor known in the current state of the art, including but not limited to optical fibre hydrogen sensors, electrochemical hydrogen sensors and thin film hydrogen sensors. Particularly, the hydrogen gas sensor may be sufficiently sensitive for detecting trace amounts of hydrogen, particularly in the gas and water vapour evaporated from the coated electrode. The hydrogen gas sensor is to be suitable for operating in regions of elevated temperature, such as an electrode drying apparatus or an electrode calendering apparatus.

[0039] Although the provision of at least one hydrogen gas sensor achieves the objectives of the present disclosure by enabling the detection of corrosion of the current collector of an electrode, and further allowing closed-loop control of various processes in the electrode manufacturing process, the present quality control methods may be further enhanced by the addition of a microwave sensor. Since corrosion of the current collector of an electrode is dependent upon the water content of the coated electrode, the provision of an additional microwave sensor capable of detecting the water content of the coated electrode is further advantageous over a hydrogen gas sensor alone, and is also synergistic with the hydrogen gas sensor. The microwave sensor is a non-contact and non-destructive sensor capable of in-situ acquisition. Further, the microwave sensor can further detect other quality parameters associated with the coated electrode in addition to the water content, allowing for further improved quality control. Accordingly, a sensor device 500 as exemplarily shown in Fig. 2 is provided by the present disclosure, wherein the sensor device 500 combines hydrogen gas sensing with microwave sensing. The sensor device 500 as illustrated includes a hydrogen gas sensor 510 configured for detecting an amount of hydrogen in the gas G being emitted from a coated electrode E, and further includes a microwave sensor. The microwave sensor includes a microwave source 540 configured for generating a microwave signal, a transmitter 520 configured for emitting the microwave signal onto the electrode E, and a receiver 530 configured to detect a reflection of the emitted microwave signal. Depending on various properties of the electrode, particularly the layers of coated electrode active material, the reflection of the microwave signal causes variations in the microwave signal which can be detected by the sensor device 500. Said variations indicate properties of the coated electrode, including but not limited to a water content of the coated electrode. The sensor device 500 further comprises a controller 550 configured for acquiring signals from the hydrogen gas sensor 510 and the receiver 530 and determining a level of quality Q therefrom.

[0040] Further to the above-described sensor device 500, the method 400 for quality control of an electrode may be further modified to include the optional microwave sensing, as illustrated by the elements of Fig. 1 marked by dashed lines. According to an embodiment, which may be combined with aspects and embodiments described herein, the method 400 further includes providing 403 at least one microwave sensor in, after or between at least one of the electrode coating apparatus, the electrode drying apparatus and an electrode calendering apparatus, the at least one microwave sensor comprising a microwave source 540, a transmitter 520 and a receiver 530. The method 400 further includes emitting 407 a microwave signal onto the electrode E using the transmitter 520, detecting 408 a reflected microwave signal being reflected from the electrode E using the receiver 530, and determining 409 at least one quality parameter Q of the electrode based on the reflected microwave signal. Particularly, the at least one quality parameter Q of the electrode is based on the reflected microwave signal and the amount of hydrogen detected by the hydrogen gas sensor 510.

[0041] The controller 550 may include the microwave source 540 for providing a microwave signal to the transmitter 520. For example, the microwave source 540 may be controllable so as to generate a specific microwave signal, or to vary the microwave signal. For example, the controllable microwave source 540 may be controlled to generate a specific microwave signal according to a first parameter for measuring one type of quality parameter, then be adjusted to a second parameter different from the first parameter to generate a specific microwave signal for measuring a different type of quality parameter. The microwave source 540 may provide at least one of a controllable power, a controllable amplitude, a controllable frequency or a controllable wave shape depending on, for example, a coating thickness of the electrode or the type of quality parameter being acquired. For the context of the present disclosure, the term “microwave” refers to waveforms having a frequency ranging from 0.3 MHz up to 40 GHz, or waveforms having a wavelength ranging from 1 mm to 1 m.

[0042] The controller 550 may further include a processing element 570 configured to determine the at least one quality parameter Q. The processing element 570 acquires at least one signal corresponding to an amount of hydrogen gas detected by the hydrogen gas sensor 510 and a signal corresponding to the reflected microwave signal detected by the receiver 530. Based on the amount of hydrogen and the reflected microwave signal, the processing element 570 determines the quality parameter Q. Particularly, the processing element 331 may compare the signal from the receiver 530 to a predetermined signal measured previously from an electrode having a known water content so as to determine the water content of the coated electrode. Alternatively, a lookup table of predetermined water content values may be used, or a predetermined model may be used to determine the water content. Similarly, the processing element 570 may compare the amount of hydrogen detected by the hydrogen gas sensor to a predetermined threshold to determine if an excessive amount of corrosion has occurred. The processing element 570 may be further configured to receive a signal and / or data corresponding to the parameters at which the controllable microwave source 540 is operating, and comparing the signal acquired from the receiver 530 to the parameters using a predetermined model to determine, for example, a variation in the microwave signal reflected from the electrode to determine the quality parameter Q.

[0043] The controller 550 may include at least one optional filtering element configured for filtering a signal from the microwave sensor. Particularly, the controller 550 may include an optional signal filtering element 560 for filtering the signal acquired by the receiver 530. For example, the signal filtering element 560 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.

[0044] The controller 550 of the sensor device 500 may be a microprocessor, a programmable logic controller (PLC), or a digital signal processor (DSP). Particularly, the controller 550 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 550 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 550 to a data network, in particular a global data network. For example, the controller 550 may be further configured to transmit at least one quality parameter to a central quality control system such that the respective coated electrode may be sorted or binned according to said quality parameter, or such that the respective electrode may be scrapped or reworked according to said quality parameter.

[0045] Preferably, the sensor device 500 is configured to operate in-situ. That is, the microwave sensor including the microwave source 540, transmitter 520 and receiver 530, as well as the hydrogen gas sensor 510 and the controller 550 are configured to operate in-situ. Similarly, the method 400 is configured to be carried out such that the reflected microwave signal is detected in-situ, the amount of hydrogen gas is detected in-situ and the determining of the quality parameter is carried out in-situ.

[0046] According to an embodiment, which may be combined with aspects and embodiments described herein, the at least one hydrogen gas sensor is configured for in-situ acquisition of the measurement of hydrogen gas. Similarly, according to a further embodiment, which may be combined with aspects and embodiments described herein, the at least one microwave sensor is configured for in-situ detection of the reflected microwave signal. 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 the electrode manufacturing process, and closed-loop control thereof is further possible.

[0047] 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 quality parameter is performed outside of a process line, for example, in a laboratory.

[0048] 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 for determining the level of corrosion of the current collector, such as time-consuming and costly analysis using scanning electron microscopes (SEM), the sensor device 300 of the present disclosure allows for faster acquisition of quality parameters such as a level of corrosion, 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.

[0049] Although the sensor device 500, particularly the microwave sensor of the sensor device 500, is exemplarily described primarily for obtaining a quality parameter Q corresponding to a water content of the coated electrode, the present disclosure is not limited thereto. The microwave sensing may be further used for detecting other quality parameters Q of the electrode. According to an embodiment, which may be combined with other embodiments described herein, the at least one quality parameter Q comprises at least one of the group containing a moisture content of the electrode, a presence of a surface defect in the electrode, a presence of a subsurface defect in the electrode, and a surface topography of the electrode. As discussed above, the implementation of a microwave sensor into the methods of the present disclosure not only allow for the synergistic detection of a water content for further improving the quality control in relation to the corrosion level of the current collector, the same microwave sensor can also contribute further quality parameters Q of the electrode, potentially removing the need for further sensors such as vision-based or laser-based sensors, particularly for detecting surface properties of the coated electrode.

[0050] The present disclosure is not limiting with respect to the arrangement or positioning of the at least one hydrogen gas sensor, and optionally the at least one microwave sensor, within the various sub-processes and processing apparatus of the electrode manufacturing system. However, a number of embodiments are preferable with respect to the respective positioning of the hydrogen gas sensor, the optional microwave sensor, and / or a sensor device 500 according to aspects of the present disclosure.

[0051] Referring now to Fig. 3, which shows an exemplarily electrode manufacturing system 100, various positions and arrangements of sensors is possible according to the present disclosure. The electrode manufacturing system 100 is exemplarily shown as including an electrode coating apparatus 110, an electrode drying apparatus 120 and an electrode calendering apparatus 130. An electrode E, or more specifically, the current collector in the form of e.g. an aluminium foil, is provided from a supply roll 101 into the electrode coating apparatus 110, in which at least one layer of electrode active material is coated. The wet-coated electrode E then passes through the electrode drying apparatus 120, which may include a number of staged drying furnaces 122a, 122b, 122c to evaporate the water from the coated electrode E. The dried electrode E then passes through the electrode calendering apparatus 130 where at least one pair of heated rollers 132a, 132b compress the coated electrode E, and the resulting electrode E is wound onto a take-up roll 102. Further details of the electrode coating apparatus 110, the electrode drying apparatus 120 and the electrode calendering apparatus 130 are known in the state of the art and are beyond the scope of the present disclosure.

[0052] The possible positions of the sensors of the present disclosure are shown by a plurality of sensor positions 301-309. The respective sensor positions 301-309 represents possible positions at which a hydrogen gas sensor, a microwave sensor, or a combined sensor including both a hydrogen gas sensor and a microwave sensor, may be positioned.

[0053] Firstly, the one or more sensors may be positioned in one of the electrode coating apparatus 110, the electrode drying apparatus 120 or the electrode calendering apparatus 130. For example, the electrode coating apparatus 110 may include a coating enclosure 111 in which the coating is performed, and a sensor position 301 may be provided. Similarly, the electrode drying apparatus 120 may include a drying enclosure 121 in which the drying is performed, and a sensor position 302 may be provided. Further, the electrode calendering apparatus 130 may include a calendering enclosure 131 in which the calendering is performed, and a sensor position 303 may be provided. These sensor positions 301, 302, 303 would be suitable for positioning of a hydrogen gas sensor and / or a microwave sensor.

[0054] In the case of the electrode drying apparatus 120, one or more sensor positions may be further provided within the separate staged drying furnaces 122a, 122b, 122c, such as at sensor position

[0055] 304, Similar to the above sensor positions 301, 302, 303, the sensor position 304 provided within a drying furnace 122a, 122b, 122c would also be suitable for positioning of a hydrogen gas sensor and / or a microwave sensor.

[0056] Optionally, the one or more sensors may be positioned between neighbouring process apparatus. For example, at least one sensor may be provided at a sensor position 305 between the electrode coating apparatus 110 and the electrode drying apparatus 120 to detect a quality parameter of a wet-coated electrode prior to drying. Alternatively, at least one sensor may be provided at a sensor position 306 between the electrode drying apparatus 120 and the electrode calendering apparatus 130 to detect a quality parameter of a dry-coated electrode prior to calendering. A further alternative would be to provide at least one sensor at a sensor position 307 after the electrode calendering apparatus 130 and before the coated electrode E is wound onto the takeup roll 102, so as to detect at least one quality parameter Q of the coated electrode prior to winding and prior to further manufacturing processes.

[0057] Although the sensor positions 305, 306, 307 positioned between or after the respective processing apparatus do not exclude the provision of a hydrogen gas sensor, the sensor positions

[0058] 305, 306, 307 are most suitable for providing a microwave sensor. Particularly, a sensor device 500 may be provided such that the microwave sensor is provided at one of sensor positions 305,

[0059] 306, 307 and the hydrogen gas sensor is provided at one of sensor positions 301, 302, 303 within the respective process apparatus. In a preferred embodiment, the electrode coating apparatus 110 and / or the electrode drying apparatus 120 each have a consolidated exhaust path through which any gas or water vapour which is emitted or evaporated from the coated electrode is collected and exhausted from the respective process apparatus. As exemplarily shown, the electrode coating apparatus 110 includes a coating apparatus exhaust path 114 for exhausting gas and water vapour from the electrode coating apparatus 110. Similarly, the electrode drying apparatus 120 exemplarily includes a drying apparatus exhaust path 124 for exhausting gas and water vapour from the electrode drying apparatus 120.

[0060] In the above-described preferred embodiment, according to an embodiment which may be combined with aspects and embodiments described herein, the at least one hydrogen gas sensor may be provided in an exhaust path 114, 124 of the electrode coating apparatus 110 and / or the electrode drying apparatus 120, and the at least one hydrogen gas sensor acquires a measurement of hydrogen gas which is present in the exhaust of the electrode coating apparatus 110 and / or the electrode drying apparatus 120. As exemplarily shown, the at least one hydrogen gas sensor may be provided at a sensor position 308 provided in the coating apparatus exhaust path 114, or may be provided at a sensor position 309 provided in the drying apparatus exhaust path 124.

[0061] Further, the electrode manufacturing system 100 may further include a water recovery system 103 which is configured to recover water which evaporates from the coated electrodes during the coating or drying processes. As exemplarily shown, the water recovery system 103 is common to both the electrode coating apparatus 110 and the electrode drying apparatus 120, and the respective exhaust paths 114, 124 direct exhausted gas and water vapor to the water recovery system 103. In cases where a water recovery system 103 is provided, a further sensor position 310 is possible wherein at least one hydrogen gas sensor is provided within the water recovery system 103. By providing the at least one hydrogen sensor in an exhaust path, particularly of a water recovery system, the at least one hydrogen sensor is provided in a region where the entire volume of emitted gas and evaporated water vapour can be analysed, leading to a more accurate detection of the amount of hydrogen emitted from the electrode.

[0062] The amount of hydrogen detected by the hydrogen sensor could further be compared to the amount of water recovered from the electrode in a water recovery system 103. For example, if the ratio of hydrogen gas detected by the hydrogen sensor to the amount of water recovered by the water recovery system 103 is below a predetermined threshold, this may indicate that the level of corrosion of the aluminium current collector is sufficiently low, indicating no quality issues. On the other hand, an elevated amount of hydrogen as compared to the amount of water recovered may indicate an excessive rate of corrosion of the aluminium current collector, indicating a quality issue.

[0063] The methods of the present disclosure may further be implemented on further processes to which the coated electrode is subjected during manufacturing. Particularly when water-based coating methods are used, the water content is desired to be as low as possible prior to assembly into an electrochemical energy storage device. After the coating, drying and calendering processes performed in the electrode manufacturing system 100 illustrated in Fig. 3, the water content of the coated electrode may be in the order of several thousand parts per million. Accordingly, an additional secondary drying process may be carried out whereby the coated electrode, after being coated, dried and calendered, is subjected to further drying in a secondary drying apparatus, so that a target water content in the order of several hundred parts per million is achieved.

[0064] Referring now to Fig. 4, a secondary drying apparatus 200 is shown. The secondary drying apparatus 200 is configured for carrying out a secondary drying process on at least one coated electrode 201, preferably wherein the at least one coated electrode 201 is in a wound coil form or in a jelly roll form. For example, the at least one coated electrode 201 may be subjected to the secondary drying process directly after calendering and before slitting, where the electrode is wound directly onto a take-up roll 102. Alternatively, the at least one electrode 201 could be in a substantially finished form whereby the electrode has been cut to size, wound and / or layered into a desired stack, jelly roll or winding, and ready for assembly into an electrochemical energy storage device.

[0065] Note that in the context of the present disclosure, any reference to an “electrode drying apparatus”, as well as features and details related thereto, are equally applicable to the secondary drying apparatus 200 described herein.

[0066] The secondary drying apparatus 200 may include a drying enclosure within which the at least one electrode 201 is dried. Here, at least one hydrogen gas sensor may be provided at sensor position 311 so as to detect an amount of hydrogen emitted from the at least one electrode 201 during the secondary drying process.

[0067] Similar to the electrode drying apparatus 120 in Fig. 3, the secondary drying apparatus 200 may include a number of drying furnaces 220a, 220b in which groups of electrodes 201 are dried. The at least one hydrogen gas sensor may be provided at sensor position 312 within one or more of the drying furnaces 220a, 220b.

[0068] According to the preferable embodiment described above, the secondary drying apparatus 200 may similarly include a drying apparatus exhaust path 202 through which all of the emitted gas and evaporated water vapour passes from the electrodes 201 being subjected to the secondary drying process. The secondary drying apparatus 200 may further include a water recover system 203 attached to said exhaust 202. In the same fashion as for the electrode drying apparatus 120 described above, the at least one hydrogen gas sensor may be positioned at a sensor position 313 within the exhaust path 202 of the secondary drying apparatus 200. Reference will now be made to Fig. 5, 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 coating apparatus 720 configured to deposit at least one layer of electrode active material onto a foil, an electrode drying apparatus 730 configured to dry the coated electrode, and an electrode calendering apparatus 740 configured for compacting the coated electrode. Further, the system 700 includes at least one hydrogen sensor positioned in at least one of the electrode coating apparatus 720 and the electrode drying apparatus 730, the at least one hydrogen sensor being configured to acquire a measurement of hydrogen gas generated during coating and / or drying of the electrode. The system 700 further includes a system control 760 configured to control the slurry mixing apparatus 710, the electrode coating apparatus 720, the electrode drying apparatus 730, the electrode calendering apparatus 740 and the assembly apparatus 750, wherein the system controller 760 is further configured to determine at least one quality parameter of at least one of the electrode based on the measurement of hydrogen gas. The coated electrode may then proceed to a subsequent process 790, such as an assembly process, a slitting process or any other processes carried out in the manufacture of an electrochemical energy storage device.

[0069] 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. 5, 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 coating apparatus 720 may include a coating controller 721 configured for controlling the electrode coating apparatus 720 according to at least one coating process parameter. Similarly, electrode drying apparatus 730 and electrode calendering apparatus 740 may each include drying controller 731 and calendering controller 741, respectively, each controller being configured for controlling the respective sub-process according to at least one process parameter.

[0070] As shown in Fig. 5, sensor devices 770, 780 are provided in-line with the various processes of system 700. The sensor devices 770, 780 shown in Fig. 5 correspond to possible positions at which the respective sensors are positioned in the system 700. In the context of the present disclosure, the term “sensor device” may refer to a sensor comprising a hydrogen sensor, a microwave sensor, or both a hydrogen sensor and a microwave sensor. Further, respective sensors arranged at different positions within a sub-process may be recognised as belonging to the same “sensor device” for the purposes of the present disclosure.

[0071] For example, the in-line sensor devices 770 which are positioned within the sub-processes may comprise a hydrogen sensor positioned in an exhaust path of the sub-process for detecting hydrogen gas emitted by the electrode within said sub-process, and additional microwave sensors arranged at the beginning and end of the sub-process for detecting water content of the electrode. As a further example, the in-line sensor devices 780 provided between sub-processes may comprise primarily at least one microwave sensor and optionally an additional hydrogen sensor provided within the preceding sub-process or subsequent sub-process for detecting hydrogen gas emitted by the electrode.

[0072] According to an embodiment, which may be combined with aspects and embodiments described herein, the at least one hydrogen sensor is provided in an exhaust path of the electrode coating apparatus and / or the electrode drying apparatus, and the at least one hydrogen sensor is configured to acquire a measurement of hydrogen gas which is present in the exhaust of the electrode coating apparatus and / or electrode drying apparatus. Particularly, the electrode coating apparatus and / or the electrode drying apparatus may include a water recovery system, and the exhaust path of the electrode coating apparatus and / or the electrode drying apparatus may be the respective water recovery path, i.e. the path from the electrode coating apparatus to the water recovery system and / or the path from the electrode drying apparatus to the water recovery system.

[0073] By providing the hydrogen sensor in an exhaust path of a water recovery system, the amount of hydrogen detected by the hydrogen sensor could further be compared to the amount of water recovered from the electrode. If the ratio of hydrogen gas detected by the hydrogen sensor to the amount of water recovered by the water recovery system is below a predetermined threshold, this may indicate that the level of corrosion of the aluminium current collector is sufficiently low as to not indicate a quality issue. On the other hand, an elevated amount of hydrogen as compared to the amount of water recovered may indicate an excessive rate of corrosion of the aluminium current collector, indicating a quality issue.

[0074] According to an embodiment, which may be combined with aspects and embodiments described herein, the system 700 further includes at least one microwave sensor positioned in, after or between at least one of the electrode coating apparatus 720, the electrode drying apparatus 730 and the electrode calendering apparatus 740, wherein the at least one microwave sensor includes a microwave source 540, a transmitter 520 and a receiver 530. The at least one microwave sensor is configured to emit a microwave signal onto the electrode E and detect a reflected microwave signal being reflected from the electrode using the receiver. Further, the system controller 760 is configured to determine the at least one quality parameter of the electrode based on the reflected microwave signal.

[0075] As discussed above, a microwave sensor in combination with the hydrogen sensor provides synergistic improvements in quality control of an electrode. Particularly, where the hydrogen gas sensor allows for the detection of corrosion which has occurred on the surface of a current collector of the electrode, the microwave sensor further allows for the real-time detection of a water content of the coated electrode, among other quality parameters. This allows for closed- loop control of the respective sub-processes to be carried out to not only react based on the corrosion detected, but also pro-actively reduce corrosion by closely controlling the water content of the coated electrode.

[0076] Each one of the sensor devices 770, 780, which may comprise its own controller, may be configured to determine the quality parameter Q at each sub-process. For example, a sensor device 770, 780 positioned in or after the electrode coating apparatus 720 may determine at least one coating quality parameter Qdepo, a sensor device 770, 780 positioned in or after the electrode drying apparatus 730 may determine at least one drying quality parameter Qdiy, and a sensor device 770, 780 positioned in or after the electrode calendering apparatus 740 may determine at least one calendering quality parameter Qcal. 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.

[0077] Alternatively, the system controller 760 may include one or more elements which implement the functions of the controller of each sensor device 770, 780. For example, the controller of each sensor device 770, 80 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.

[0078] 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 electrode, electrochemical energy storage device, or batch thereof, may be sorted or binned according to said quality parameter Q.

[0079] 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 which is 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. 5, the system controller 760 may be configured to adjust the process parameters of each subprocess based on a system -wide predetermined model 761.

[0080] 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, 780 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 coating process APcoat, the drying process APdryand the calendering process APca[so 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.

[0081] 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.

[0082] Preferably, the predetermined model 761 includes a predetermined empirical model. Empirical data can be generated through operation of 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.

[0083] 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 or a calendered electrode to be obtained quickly and reliably. In particular, a level of corrosion of the electrode, particularly the current collector, may be determined at various stages in the electrode manufacturing process. Further, the closed- loop control systems allow for variations in raw material quality, mixed slurry quality, coating quality, water content 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.

[0084] 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 electrode for an electrochemical energy storage device is provided, the method comprising performing at least one manufacturing process to produce the electrode 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 electrode 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.

[0085] The at least one manufacturing process according to the method above may be further controlled by using e.g. feed-forward of the at least one quality parameter Q acquired or determined in a preceding manufacturing process, or free-back of the at least one quality parameter Q acquired or determined in a subsequent manufacturing process. Preferably, the method according to the above aspect may include any one of the following control schemes. According to an embodiment, which may be combined with aspects and embodiments described herein, the at least one manufacturing process includes a slurry mixing process being controlled based on at least one slurry mixing process parameter, the hydrogen sensor and optionally the microwave sensor are provided in at least one of a subsequent electrode coating process, a subsequent electrode drying process and a subsequent electrode calendering process, and the at least one slurry mixing process parameter is adjusted based on the at least one quality parameter using a predetermined slurry mixing model. Such an embodiment allows for closed-loop control of the slurry mixing process based on, for example, a level of corrosion or a water content of the electrode detected at a later stage in the manufacturing process.

[0086] Particularly, the process parameters of the slurry mixing process may be adjusted so as to change the slurry mixing recipe or to include a corrosion inhibitor or a pH buffer. According to an embodiment which may be combined with other embodiments described herein, the at least one process parameter includes an amount of a corrosion inhibitor, an amount of pH buffer and / or an amount of water to be fed into the slurry mixing process according to a slurry mixing recipe, the at least one quality parameter includes a level of corrosion of a foil of the electrode based on the measurement of hydrogen gas acquired by the at least one hydrogen gas sensor, and the amount of corrosion inhibitor, the amount of pH buffer and / or the amount of water to be fed into the slurry mixing process is adjusted based on the level of corrosion. According to an embodiment, which may be combined with aspects and embodiments described herein, the at least one manufacturing process comprises an electrode coating process being controlled based on at least one coating process parameter, the hydrogen sensor and optionally the microwave sensor are provided in at least one of the electrode coating process, a subsequent electrode drying process and a subsequent electrode calendering process, and the at least one coating process parameter is adjusted based on the at least one quality parameter using a predetermined coating model. Such an embodiment allows for closed-loop control of the coating process based on, for example, a level of corrosion or a water content of the electrode detected at a later stage in the manufacturing process. For example, the coating process may be adjusted so that a corrosion inhibiting coating may be applied to the current collector prior to the electrode active material being coated thereon if, for example, the amount of corrosion in a subsequent process is excessive or if the water content of the slurry resulting from the slurry mixing process is excessive.

[0087] According to an embodiment, which may be combined with aspects and embodiments described herein, the at least one manufacturing process comprises an electrode drying process being controlled based on at least one drying process parameter; the hydrogen sensor and optionally the microwave sensor are provided in at least one of a preceding electrode coating process, the electrode drying process and a subsequent electrode calendering process, and the at least one drying process parameter is adjusted based on the at least one quality parameter using a predetermined drying model. Such an embodiment allows for closed-loop control of the drying process based on, for example, a water content of the electrode detected at an earlier stage (feed-forward) or at a later stage (feed-back) in the manufacturing process. Particularly, the process parameters of the electrode drying process may be adjusted so as to change various parameters of the drying based on a water content in the electrode. According to an embodiment which may be combined with other embodiments described herein, the at least one process parameter includes a drying time, a drying power and / or a drying temperature of the electrode drying process, the at least one quality parameter includes a moisture content of the electrode acquired by the at least one microwave sensor, and the drying time, the drying power and / or the drying temperature is adjusted based on the moisture content. Accordingly, the drying process can be automatically adapted to suit the amount of water which is to be evaporated from the coated electrode so that water content targets can be met, but also as a preventative measure to reduce the amount of corrosion of the current collector of the electrode.

[0088] 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.

[0089] Spatially relative terms such as “under”, “below”, “lower”, “over”, “upper”, “downstream”, “upstream” 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.

[0090] 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.

[0091] 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

[0092] 100 System for manufacturing an 407 Emitting a microwave signal electrode 408 Detecting a reflected

[0093] 101 Supply roll micro wave signal

[0094] 102 Take-up roll 409 Determining the at least one

[0095] 103 Water recovery system quality parameter

[0096] 110 Electrode coating apparatus 410 Method end

[0097] 111 Coating enclosure 500 Sensor device

[0098] 114 Coating apparatus exhaust path 501 Roller

[0099] 120 Electrode drying apparatus 510 Hydrogen gas sensor

[0100] 121 Drying enclosure 520 Microwave emitter

[0101] 122a-c Drying furnace 530 Microwave receiver

[0102] 124 Drying apparatus exhaust path 540 Microwave source

[0103] 130 Electrode calendering apparatus 550 Sensor controller

[0104] 131 Calendering enclosure 560 Signal filter

[0105] 132a-b Calendering rollers 570 Processing element

[0106] 200 Secondary drying apparatus 700 System for manufacturing an

[0107] 201 Electrode rolls electrode

[0108] 202 Drying apparatus exhaust path 710 Slurry mixing apparatus

[0109] 203 Water recovery system 711 Mixing controller

[0110] 210 Drying enclosure 720 Electrode coating apparatus

[0111] 220a-b Drying furnace 721 Coating controller

[0112] 301-313 Sensor positions 730 Electrode drying apparatus

[0113] 400 Method for quality control of an 731 Drying controller electrode 740 Electrode calendering apparatus

[0114] 401 Method start 741 Calendering controller

[0115] 402 Providing at least one hydrogen 760 System controller gas sensor 761 Predetermined model

[0116] 403 Providing at least one 770, 780 In-line sensor device microwave sensor 790 Subsequent process

[0117] 404 Coating an electrode E Electrode

[0118] 405 Drying an electrode G Gas emitted from electrode

[0119] 406 Acquiring a measurement of Q Quality parameter hydrogen gas AP Adjusted process parameter

Claims

Claims1. A method for quality control of an electrode for an electrochemical energy storage device, the method comprising: providing at least one hydrogen gas sensor in at least one of an electrode coating apparatus and an electrode drying apparatus; carrying out at least one of coating an electrode in the electrode coating apparatus and drying an electrode in the electrode drying apparatus; acquiring a measurement of hydrogen gas being generated during the coating and / or the drying; and determining at least one quality parameter of the electrode based on the measurement of hydrogen gas.

2. The method according to claim 1, wherein the at least one hydrogen gas sensor is configured for in-situ acquisition of the measurement of hydrogen gas.

3. The method according to any one of claims 1 to 2, wherein the electrode comprises a continuous foil coated with at least one layer of electrode active material, and the at least one quality parameter corresponds to a level of corrosion of the foil.

4. The method according to any one of claims 1 to 3, wherein the at least one hydrogen gas sensor is provided in an exhaust path of the electrode coating apparatus and / or the electrode drying apparatus, and the at least one hydrogen gas sensor acquires a measurement of hydrogen gas which is present in the exhaust of the electrode coating apparatus and / or the electrode drying apparatus, particularly wherein the exhaust path is a water recovery path.

5. The method according to any one of claims 1 to 4, further comprising: providing at least one microwave sensor in, after or between at least one of the electrode coating apparatus, the electrode drying apparatus and an electrode calendering apparatus, the at least one microwave sensor comprising a microwave source, a transmitter and a receiver; emitting a microwave signal onto the electrode using the transmitter; detecting a reflected microwave signal being reflected from the electrode using the receiver; and determining at least one quality parameter of the electrode based on the reflected micro wave signal.

6. The method according to claim 5, wherein the at least one microwave sensor is configured for in-situ detection of the reflected microwave signal.

7. The method according to claim 5, wherein the at least one quality parameter comprises at least one of the group containing: a moisture content of the electrode; a presence of a surface defect in the electrode; a presence of a subsurface defect in the electrode; and a surface topography of the electrode.

8. A method for manufacturing an electrode for an electrochemical energy storage device, the method comprising:performing at least one manufacturing process to produce the electrode 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 electrode using the method according to any one of claims 1 to 9; and adjusting the at least one process parameter based on the at least one quality parameter according to a predetermined process model.

9. The method according to claim 8, characterized by at least one of the following: the at least one manufacturing process comprises a slurry mixing process being controlled based on at least one slurry mixing process parameter; the hydrogen sensor and optionally the microwave sensor are provided in at least one of a subsequent electrode coating process, a subsequent electrode drying process and a subsequent electrode calendering process; and the at least one slurry mixing process parameter is adjusted based on the at least one quality parameter using a predetermined slurry mixing model; the at least one manufacturing process comprises an electrode coating process being controlled based on at least one coating process parameter; the hydrogen sensor and optionally the microwave sensor are provided in at least one of the electrode coating process, a subsequent electrode drying process and a subsequent electrode calendering process; and the at least one coating process parameter is adjusted based on the at least one quality parameter using a predetermined coating model; and / or the at least one manufacturing process comprises an electrode drying process being controlled based on at least one drying process parameter; the hydrogen sensor and optionally the microwave sensor are provided in at least one of a preceding electrode coating process, the electrode drying process and a subsequent electrode calendering process; and the at leastone drying process parameter is adjusted based on the at least one quality parameter using a predetermined drying model.

10. The method according to any one of claims 8 to 9, wherein: the at least one process parameter includes an amount of a corrosion inhibitor, an amount of pH buffer and / or an amount of water to be fed into the slurry mixing process according to a slurry mixing recipe; the at least one quality parameter includes a level of corrosion of a foil of the electrode based on the measurement of hydrogen gas acquired by the at least one hydrogen gas sensor; and the amount of corrosion inhibitor, the amount of pH buffer and / or the amount of water to be fed into the slurry mixing process is adjusted based on the level of corrosion.

11. The method according to any one of claims 8 to 10, wherein the at least one process parameter includes a drying time, a drying power and / or a drying temperature of the electrode drying process; the at least one quality parameter includes a moisture content of the electrode acquired by the at least one microwave sensor; and the drying time, the drying power and / or the drying temperature is adjusted based on the moisture content.

12. System for manufacturing an electrode for an electrochemical energy storage device, the system comprising: a slurry mixing apparatus configured for mixing a slurry of electrode active material according to a slurry mixing recipe;an electrode coating apparatus configured to deposit at least one layer of the electrode active material onto a foil; an electrode drying apparatus configured to dry the coated electrode; an electrode calendering apparatus configured for compacting the coated electrode; at least one hydrogen sensor positioned in at least one of the electrode coating apparatus and the electrode drying apparatus, the at least one hydrogen sensor being configured to acquire a measurement of hydrogen gas generated during coating and / or drying of the electrode; and a system controller configured to control the slurry mixing apparatus, the electrode coating apparatus, the electrode drying apparatus and the electrode calendering apparatus, wherein the system controller is further configured to determine at least one quality parameter of the electrode based on the measurement of hydrogen gas.

13. The system according to claim 12, wherein the at least one hydrogen sensor is provided in an exhaust path of the electrode coating apparatus and / or the electrode drying apparatus, and the at least one hydrogen gas sensor is configured to acquire a measurement of hydrogen gas which is present in the exhaust of the electrode coating apparatus and / or the electrode drying apparatus, particularly wherein the exhaust path is a water recovery path.

14. The system according to any one of claims 12 to 13, further comprising: at least one microwave sensor positioned in, after or between at least one of the electrode coating apparatus, the electrode drying apparatus and the electrode calendering apparatus, wherein the at least one microwave sensor comprises a microwave source, a transmitter and a receiver,wherein the at least one microwave sensor is configured to emit a microwave signal onto the electrode and detect a reflected microwave signal being reflected from the electrode using the receiver, and wherein the system controller is further configured to determine the at least one quality parameter of the electrode based on the reflected microwave signal.

15. The system according to any one of claims 12 to 14, wherein the system controller is configured to carry out the method according to any one of claims 1 to 11.

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