Method for producing a battery electrode, method for producing a battery cell winding, and battery cell having such a battery electrode

Abstract

The invention relates to a method for producing a battery electrode which is intended for use in an electrochemical battery cell, said battery electrode comprising a battery electrode carrier film (1), said battery electrode carrier film (1) being coated on at least one side with a battery electrode active material (3), so-called battery electrode active material layer (17), and said battery electrode active material layer (17) having so-called battery electrode active material pores which are completely or partially surrounded by pore-free active material, the method comprising the following steps: - providing the battery electrode carrier film (1) in the form of a strip which has a carrier film width in a carrier film width direction (21) and a carrier film length in a carrier film longitudinal direction, - transporting the battery electrode carrier film in the direction of the carrier film longitudinal direction (5), so-called production direction, - applying the battery electrode active material (3) to at least one side of the battery electrode carrier film (1) in order to produce a coated battery electrode carrier film, the carrier film (1) being covered at least in parts in the carrier film width and the carrier film length, - determining the composition of the applied battery electrode active material with respect to the proportion of the battery electrode active material pores and the proportion of the pore-free active material, so-called active material porosity, wherein the active material porosity is detected at a first location in the carrier film longitudinal direction (5) and at a plurality of further locations different from said first location, and wherein the active material porosity is thus detected at a plurality of different locations of the battery electrode in the carrier film longitudinal direction (5).

Description

[0001] 24-0119 PIF

[0002] 1

[0003] Method for manufacturing a battery electrode, method for manufacturing a battery cell winding and battery cell with such a battery electrode

[0004] The invention relates to a method for manufacturing a battery electrode. US Patent 2006 / 0151318 A1 discloses an electrode for an electrochemical battery cell, a method for manufacturing such a cell, and a battery cell with such an electrode.

[0005] The invention is described below using an energy storage cell for use in a high-voltage storage system of an electric passenger car; this is not to be understood as limiting the invention to such an application. A battery electrode has a film coated with so-called "active material," this film representing the current collector. The active material is porous, and the electrolyte is absorbed into the pores of this porosity. It is known that the porosity of a battery electrode influences its performance, in particular its charging and discharging characteristics.

[0006] Energy storage cells for high-voltage automotive batteries are known in various designs. These designs share the common feature of exhibiting a large number of electrode layers in a cross-section. Therefore, the geometric characteristics of such an electrode, particularly its thickness (the thickness of the active material layer on the current collector), are subject to stringent requirements, as even slight variations in layer thickness can lead to significant deviations in the energy storage cell due to the large number of layers.

[0007] A general goal is to achieve the most consistent possible manufacturing of a battery electrode, which in particular means that a consistent mass of active material with a consistent layer thickness and porosity is applied to the current collector. Furthermore, the aforementioned properties (amount of active material applied, porosity of the active material, layer thickness of the active material) influence each other; for example, with a constant amount of active material, a layer with higher porosity will have a greater layer thickness than a layer of the same active material with lower porosity.

[0008] It is an object of the invention to provide a method which enables the production of an improved battery electrode, as well as a method for producing a battery- 24-0119 PIF

[0009] The object of this project is to specify two battery cell windings and a battery cell with a battery electrode produced in this manner. This problem is solved by a method according to claims 1 and 7 and by a battery cell according to claim 9.

[0010] In the mass production of a battery electrode, particularly for a lithium-ion battery cell, the continuous measurement of the porosity of the active material applied to the carrier film is currently not performed. To achieve consistently high manufacturing quality of the battery electrode, the invention therefore proposes measuring the porosity of the battery electrode active material applied to the carrier film, the so-called battery electrode carrier film, and in particular measuring this continuously. Furthermore, at least three measurement methods are proposed for such a measurement of the porosity, so-called active material porosity.

[0011] The first proposed measurement method is a combined system consisting of an areal weight measurement using X-rays in combination with a thickness measurement for the same section for which the areal weight is determined. Specifically, this thickness measurement measures the thickness of the battery electrode active material applied to the battery electrode support film, the so-called active material layer thickness. From the determined areal weight and the determined active material layer thickness, the porosity of the applied active material for this section can be calculated.

[0012] The second proposed measurement method is based on a radiological imaging technique, in particular computed tomography (CT), for determining the active material porosity. In such a method, a cross-sectional image of the battery electrode active material applied to the battery electrode carrier film is generated using a radiological technique. Preferably, the porosity of the battery electrode active material examined at this point can be determined from this cross-sectional image using an image analysis method.

[0013] The third proposed measurement method is also based on an imaging technique to determine a cross-sectional image of the layer of battery electrode active material applied to the battery electrode carrier foil. This third measurement method utilizes magnetic resonance imaging, or MRI technology for short. Furthermore, it is proposed that the measurement evaluation for this third method be carried out in the same manner as for the second measurement method, with the difference that the third measurement method uses MRI technology, while the second measurement method... 24-0119 PIF

[0014] The third method is CT technology. Both measurement methods mentioned have in common that a cross-sectional image of the battery electrode active material layer applied to the battery electrode carrier film is generated.

[0015] Compared to the first measurement method, which is not based on an imaging technique and thus relies on a non-imaging method for determining active material porosity, the second and third measurement methods offer the advantage that, in an imaging technique, active material porosity is not only determined as a quantified quantity. Rather, based on an imaging technique (second and third measurement methods), it is possible to also capture the geometric characteristics of the pores in the battery electrode active material layer that define this porosity, the so-called morphology of the porosity, and in particular to determine their distribution and shape. Furthermore, particles, especially particles of the active material and particles of a binder material, can also be detected in an imaging technique.

[0016] In particular, the factors mentioned above influence the operating characteristics of the battery electrode and thus of the battery cell in which this electrode is used, and can especially affect the lifespan and charging capacity, particularly the fast-charging capability, of this battery cell. Continuous monitoring of the porosity of a battery electrode in the proposed manner makes it possible to reduce manufacturing scrap costs and improve output performance, as the operating characteristics of a battery cell can be assessed as early as the electrode manufacturing stage.

[0017] Furthermore, it is proposed to assign the data obtained during manufacturing using one of the aforementioned measurement methods to a specific length segment of the battery electrode being manufactured via a data matrix code. This approach, in turn, makes it possible to selectively assign a first battery electrode, the anode, to a second battery electrode, the cathode, resulting in a battery cell with improved operating characteristics. It is also possible to manufacture a battery cell with a matched anode, cathode, and preferably also a separator between these two, using battery electrodes whose active material porosity is known and, as previously described, measured along their length. In particular, by measuring the porosity of the active material layer, i.e., the active material porosity, in a longitudinal direction of the battery electrode, it is possible to increase the performance of the battery cell. 24-0119 PIF

[0018] 4

[0019] Such a battery cell comprises at least a cathode, an anode, and a separator to provide its electrochemical operating characteristics. Recognizing that the active material porosity of the battery electrode influences the operating characteristics of the battery cell, the battery electrodes can be combined in such a way as to produce a battery cell with improved operating characteristics. This process, in which different components are "matched" together—"matched" in this context meaning that the combination achieves an improved overall result—is also known as pancake matching.

[0020] It is therefore further proposed to apply an assignment rule according to which different battery electrodes or a battery cell separator and at least one of these battery electrodes are aligned with each other, in particular aligned with each other in the longitudinal direction, or preferably, "matching" pairs are selected. In particular, such an assignment rule can take into account different optimization goals, in particular a particularly high charge / discharge capacity or service life, or the like.

[0021] In other words, a problem in the production of a battery electrode and a battery cell with such a battery electrode is that, although it is recognized that the porosity in the active material (active material porosity) of the battery electrode influences its performance, this active material porosity is not currently measured in the ongoing manufacturing process. Therefore, this parameter is not used for optimization in production; thus, there is no alignment or selection of a battery electrode relative to another battery electrode or to a separator with respect to porosity, or a progression of the porosity in a longitudinal direction of the battery electrode.

[0022] By using an assignment rule that enables "optimal" alignment or selection of the battery electrode in the longitudinal direction against another battery electrode or a separator, the performance (output power, fast-charging capability, cycle stability) of a battery cell based on such a battery cell winding can be improved. Such an assignment rule can be based on simulation, model, or experimental data. 24-0119 PIF

[0023] 5

[0024] A fundamental principle of the invention is therefore to determine the composition of the layer of battery electrode active material applied to the carrier film of the battery electrode, the so-called battery electrode active material layer, during the production process; this can be understood as an in-line measurement. The battery electrode active material layer has pores, so-called battery electrode active material pores, which are completely or partially enclosed by pore-free active material. In the aforementioned in-line measurement, the composition of this battery electrode active material layer is determined with respect to the ratio, in particular a volume ratio, of the battery electrode active material pores and the surrounding pore-free active material, the so-called active material porosity.In-line measurement of the battery electrode active material layer determines the active material porosity at different locations along the longitudinal direction of the battery electrode during its production. The result of this in-line measurement is therefore a porosity profile of the battery electrode active material layer along its longitudinal direction, the so-called active material porosity.

[0025] Furthermore, it is proposed that, based on data tracking, the measured active material porosity be used for subsequent cell formation, i.e., the assembly of a battery cell with a battery electrode produced using the proposed method. In general, the measurement of the active material porosity can be carried out in two groups of methods. The first group involves determining the basis weight of the battery electrode active material applied to the substrate film by X-ray transmission combined with a thickness measurement to calculate an average active material porosity for a specific section. The second group involves acquiring cross-sectional images of the battery electrode active material layer using suitable imaging techniques and subsequently evaluating the image data using an analysis method.

[0026] In a preferred embodiment of the invention, for examining the battery electrode using an X-ray device, preferably for thickness measurement using such a device, it is proposed to scan it with a scanning power in kilovolts (kV) of more than 2.5, preferably more than 4, and particularly preferably 5 or more, and further preferably 200 or less, more preferably 150 or less, and particularly preferably 100 or less. It is further preferably proposed that, for examining the battery electrode using an X-ray device, preferably for thickness measurement using such a device, it be scanned with a scanning power of 24-0119 PIF.

[0027] 6. Scanning current in milliamperes (mA) of less than 2, preferably less than 1.5 and particularly preferably 1 or less.

[0028] In a preferred embodiment of the invention, for examining the battery electrode using a computed tomography (CT) system, it is proposed that such a system be scanned with a scanning power in kilovolts (kV) of more than 0, preferably more than 5, and particularly preferably 10 or more, and further preferably 300 or less, more preferably 250 or less, and particularly preferably 200 or less. It is further preferably proposed that, for examining the battery electrode using a computed tomography (CT) system, the system be operated at a voxel size of more than 20 nanometers, more preferably more than 30 nanometers, and particularly preferably 40 or more nanometers, and at 300 micrometers or less, more preferably 250 micrometers or less, and particularly preferably 200 micrometers or less.It is further preferably proposed that, for the examination of the battery electrode using a computed tomography (CT) system, such a system be scanned with a scanning current in microamperes (scanning current [A]) of less than 2000, preferably less than 1500, and particularly preferably 1000 or less. In particular, with the aforementioned values, an efficient and precise determination, especially of the active material porosity, is enabled.

[0029] It is further preferably proposed to achieve a contrast agent for improving the measurement results using an X-ray method, computed tomography method, or magnetic resonance method, and it is more preferably proposed to use such a contrast agent as a component of the active material applied to the carrier film, preferably a solvent. In particular, a solvent of the active material evaporates at least partially or completely by the time the battery cell is completed, and with it the contrast agent, so that it has no effect on the operating characteristics of the battery cell as such.

[0030] In such a cross-sectional image, the determination of which has been explained previously, both the geometric extent of the battery electrode active material layer in this section and the area ratio of the active material pores to the non-porous active material can be discerned, thus allowing the active material porosity at the location of the battery electrode where the cross-sectional image is taken to be determined. If a series of cross-sectional images are taken at different locations along the longitudinal direction of the battery electrode, the distribution of this porosity, and thus the active material porosity, can be determined. 24-0119 PIF

[0031] 7

[0032] Preferably, such a cross-sectional image extends in the width direction of the battery electrode and preferably at least substantially over its entire width.

[0033] Furthermore, the evaluation method can be supplemented by a procedure in which the performance data of a battery cell are compared with the active material porosity of the battery electrode contained in that battery cell. Based on this procedure, an assignment rule for the active material porosity of one battery electrode can be determined in relation to the active material porosity of a second battery electrode or a separator, or the porosity of a sparator. Preferably, such an evaluation method employs an artificial intelligence method, or a method containing artificial intelligence components.

[0034] In figurative terms, such a method can be understood as an optimization process in which the active material porosity of at least one battery electrode is adapted to other parameters, such as, in particular, the porosity of a separator or another battery electrode. In this context, the active material porosity, or the porosity of the separator, is to be understood, as explained, as the porosity along its longitudinal extent. With the proposed method, which can preferably be designed as a self-learning process, it is possible to classify non-performing battery electrodes as such, both during the proposed manufacturing process and, in particular, already during the coating of the carrier films with battery electrode active material.

[0035] In particular, this process makes it possible to reduce scrap costs compared to conventional manufacturing and also enables the production of particularly reliable battery cells. In conventional production, battery cells that do not meet requirements, especially due to suboptimal active material porosity, are often only identified as such in a test at the end of production, a so-called end-off-line test. The proposed manufacturing process allows for the early detection of such battery cells well before their production, thus significantly improving production efficiency.

[0036] Furthermore, as already explained, it is possible to perform porosity matching, preferably between a separator and at least one battery electrode, whereby an "optimally" matched set of at least one battery electrode and a separator, with respect to their porosities, is assembled in a battery cell. Insbeson- 24-0119 PIF

[0037] 8. It is assumed that the porosity distribution, i.e., the active material porosity, does not change significantly during continuous coating of the battery electrode carrier film with the battery electrode active material layer. However, a variation in the active material porosity can occur between different production batches, particularly of the active material, and this can be influenced and adjusted to the desired level by means of the plant parameters, preferably a drying gradient during the drying of the battery electrode active material layer, preferably a line load during the mechanical compaction of the battery electrode active material layer (so-called calendering), or a combination of these parameters.

[0038] Preferably, the active material porosity can be measured not just at one point along the battery electrode manufacturing process, but after different production steps, and thus multiple times. In particular, the arrangement of suitable measuring devices along the production line is advantageous in order to obtain a complete picture of the active material porosity, i.e., the porosity distribution in the battery electrode active material layer in the longitudinal direction.

[0039] Preferably, the porosity of the active material is measured during the application of the active material to the carrier film, whereby this application can be carried out on one or both sides of the carrier film. More preferably, measurement is taken after the active material layer has dried, and even more preferably, measurement is taken after mechanical compaction. It is also more preferably possible to measure the porosity of the separator.

[0040] For the purposes of the invention, a method for manufacturing a battery electrode is understood to be a method or a partial method for manufacturing a battery electrode for an electrochemical battery, in particular a lithium-ion battery, wherein this battery electrode has a porosity for receiving an electrolyte. The battery electrode has a battery electrode support film which is coated on at least one side with a battery electrode active material, a so-called battery electrode active material layer, preferably on both sides. The battery electrode support film is designed as a film-like component or element and is also referred to as a current collector or current conductor. As explained, the battery electrode active material layer has pores, so-called battery electrode active material pores, which are completely or partially surrounded by pore-free active material.24-0119 PIF.

[0041] 9

[0042] The proposed manufacturing process includes at least the following steps:

[0043] - Providing the battery electrode carrier film in the form of a strip which has a carrier film width in a carrier film width direction and a carrier film length in a carrier film longitudinal direction,

[0044] - Transporting the battery electrode carrier film in the direction of the carrier film's longitudinal direction, so-called production direction,

[0045] - at least one-sided application of the battery electrode active material to the battery electrode carrier film in order to produce a coated battery electrode carrier film which covers the carrier film at least section by section in the carrier film width and the carrier film length,

[0046] - Determining the composition of the applied battery electrode active material with respect to the proportion of battery electrode active material pores and the proportion of pore-free active material, so-called active material porosity, wherein the active material porosity is determined at a first location in the longitudinal direction of the carrier film and at a multitude of other locations which deviate from this first location, and wherein the active material porosity is thus determined at a multitude of different locations of the battery electrode in the longitudinal direction of the carrier film.

[0047] Preferably, the battery electrode support film is designed as a film-like element, in particular a thin-film, electrically conductive film, and is further preferably wound onto a roll from which it is unwound to manufacture the battery electrode. In particular, the battery electrode support film is thus unwound from the roll as a virtually endless strip. In particular, "thin-film" means a film thickness of a few micrometers, preferably a few hundredths of a millimeter, and further preferably, the length of the battery electrode support film is much greater than its width.

[0048] Furthermore, during the manufacture of the battery electrode, the battery electrode carrier film is transported through a production plant, in particular in its longitudinal direction through this production plant and thus unwound from the roll on which it is provided, whereby this unwinding direction and thus the longitudinal extent of the battery electrode carrier film corresponds to the production direction, i.e. the direction in which the battery electrode carrier film is conveyed through the production plant.

[0049] Furthermore, during manufacturing, the so-called battery electrode active material is applied to the battery electrode carrier film in the form of a battery electrode active material layer, so that the battery electrode carrier film, at least substantially, in its longitudinal extent and in its width, at least on one side or on both sides 24-0119 PIF

[0050] 10. The active material is applied over a large area to the battery electrode carrier film, meaning that it is coated on one or preferably both sides with the battery electrode active material, thus forming a coated battery electrode carrier film. "At least substantially with regard to the extent of the battery electrode active material layer" in the context of the invention means, in particular, that one or more areas of the battery electrode carrier film are uncoated, especially to enable electrical contact of the battery electrode carrier film in a battery cell. Furthermore, it may be necessary for one or more areas of the battery electrode carrier film to remain uncoated, particularly due to the production process.

[0051] After applying at least one layer of battery electrode active material to the battery electrode support film, it is proposed to determine the composition of this layer with respect to its porosity. This porosity in the battery electrode active material layer, known as active material porosity, is a measure of the ratio between pores in this battery electrode active material layer and the surrounding, non-porous battery electrode active material. The active material porosity, as defined by the invention, is determined at different locations within the battery electrode active material layer along the longitudinal direction of the battery electrode. Figuratively speaking, the active material porosity can be understood as a distribution of the porosity along the longitudinal direction of the battery electrode, determined at discrete locations.If this porosity were theoretically determined at an infinite number of locations along the longitudinal direction of the battery electrode, a complete profile would be known. Therefore, in the proposed method, the porosity of the battery electrode active material layer is determined at a first location along the longitudinal direction of the battery electrode and at at least one further location, differing from this first location along the longitudinal direction, and preferably at a plurality of these further locations along this longitudinal direction of the battery electrode. Preferably, all of these further locations have different positions along this longitudinal direction. Furthermore, and more preferably, the porosity determined at one location represents a value for the porosity over the entire width of the battery electrode active material layer or, more preferably, over a specific width range thereof.Preferably, the determination of the active material porosity is carried out while the battery electrode is transported in the production direction, whereas the device for determining this is stationary.

[0052] The invention is thus based on the understanding that the active material porosity has an influence on the performance of a battery cell with such a battery electrode. In particular, by measuring the active material porosity in the manner described 24-0119 PIF

[0053] 11 enables early detection of the properties of a battery cell before it is even manufactured; furthermore, it enables the properties of a battery cell with such a battery electrode to be influenced by a "suitable" selection of other components of the battery cell, i.e., in particular, matching the active material porosity of this battery electrode.

[0054] In a preferred embodiment, it is proposed to determine the active material porosity by measuring the morphology of the active material pores, at least in a cross-section of the battery electrode active material layer, preferably orthogonal to its longitudinal direction, and at least the thickness of the at least one battery electrode active material layer applied to the battery electrode support film, at this first location and at at least one of these further locations.

[0055] Preferably, an X-ray device is provided to detect the morphology of the active material pores, and a contact or non-contact geometry measuring device is provided to determine the active material layer thickness. An imaging method is proposed using an X-ray device; such radiological methods are known in the prior art. In particular, a predetermined area of ​​the battery electrode can be "illuminated" using the X-ray device, and the thickness of the battery electrode's active material layer for this illuminated area is then determined using the geometry measuring device. Since this procedure is carried out for several locations (first location, subsequent locations) of the battery electrode, the active material porosity distribution in the longitudinal direction of the substrate film can be determined, i.e., the active material porosity.

[0056] In a preferred embodiment, the active material layer thickness is measured using a tactile measuring method, i.e., a contact measuring method, and in a further preferred embodiment, this measurement is performed using a non-contact measuring method. In particular, contact measurement enables simple and efficient measurement of the active material layer thickness. In particular, a non-contact measuring method enables measurement of the active material layer thickness without affecting the battery electrode active material layer itself.

[0057] In a preferred embodiment of the invention, a method for producing a battery electrode is proposed in which, to determine the active material porosity, i.e., to determine the morphology of the active material pores and at least additionally also the active material layer thickness, at this first location and at least one of these further locations, 24-0119 PIF

[0058] 12

[0059] The proposed method employs a radiological imaging technique, such as computed tomography, to visualize the battery electrode's active material layer at each of these locations, i.e., at this first location and at least one or all of these additional locations. Preferably, a cross-sectional image is understood to be an image covering the entire cross-sectional area, particularly orthogonal to the longitudinal direction of the battery electrode or a region of this cross-sectional area of ​​the battery electrode's active material layer.Since such a procedure is carried out for several locations (first location, further locations) of the battery electrode, an active material porosity distribution in the longitudinal direction of the carrier film can be determined, i.e. the active material porosity.

[0060] In a further preferred embodiment of the invention, an imaging method based on the application of magnetic fields and radio waves, such as magnetic resonance imaging, is proposed for determining the active material porosity, in particular for determining the morphology of the active material pores and at least additionally also the active material layer thickness at this first location and at at least one of these further locations. In particular, by means of an imaging method based on the aforementioned technology, it is possible to generate at least one cross-sectional image of the battery electrode active material layer at each of these locations (first location, at least one further location).It is further proposed that this imaging method, based on magnetic fields and radio waves, generates at least one cross-sectional image of the battery electrode active material layer at each of these locations, i.e., at this first location and at least one of these further locations, or at all of these further locations. Preferably, a cross-sectional image is understood to be an image over the entire cross-sectional area, in particular orthogonal to this longitudinal direction of the battery electrode or over a region of this cross-sectional area of ​​this battery electrode active material layer. Since such a procedure is carried out for several locations (first location, further locations) of the battery electrode, an active material porosity distribution in the longitudinal direction of the support film, i.e., the active material porosity, can be determined.

[0061] In a preferred embodiment of the invention, after the battery electrode active material has been applied as a battery electrode active material layer, this layer is dried. It is further proposed that this at least one battery electrode active material layer be mechanically compacted after this drying, so-called Ka- 24-0119 PIF

[0062] 13. In this preferred embodiment of the invention, to determine the active material porosity, the composition of the applied battery electrode active material is determined at least once more with respect to the proportion of battery electrode active material pores and the proportion of pore-free active material at at least two different locations of the battery electrode in the longitudinal direction of the carrier film after drying. In particular, by this further determination of the active material porosity—thus determining it at least twice during the manufacture of the battery electrode, after drying the battery electrode active material layer—an active material porosity before drying and a further active material porosity after drying are known.Furthermore, the active material porosity distribution in the longitudinal direction of the carrier film was determined before and after drying, allowing for the assessment of the influence of specific manufacturing steps on the active material porosity. In particular, such a further, or repeated, determination of the active material porosity after drying allows the influence of drying on the active material porosity to be determined and evaluated, thus enabling an improvement in production efficiency, as the drying process can be adjusted based on the results obtained.

[0063] In a preferred embodiment of the invention, after the battery electrode active material has been applied as a battery electrode active material layer in the production direction, this layer is dried. Furthermore, this battery electrode active material layer is mechanically compacted after drying. In this embodiment of the invention, it is proposed to determine the active material porosity, or a further active material porosity, at least once more the composition of the applied battery electrode active material with respect to the proportion of battery electrode active material pores and the proportion of pore-free active material at at least two different locations of the battery electrode in the longitudinal direction of the carrier film after this mechanical compaction. In particular, in this embodiment, an active material porosity distribution in the longitudinal direction of the carrier film is thus determined before and after this mechanical compaction.In particular, by measuring the active material porosity of the battery electrode active material layer after mechanical compaction, the influence of mechanical compaction on this layer can be determined, thus enabling an increase in production quality.

[0064] In a preferred embodiment of the invention, after each of the production steps (application of at least one battery electrode active material layer, drying of at least one such battery electrode active material layer, mechanical compaction of such a 24-0119 PIF

[0065] The active material porosity was determined in the 14 dried battery electrode active material layer. In particular, such a detailed determination of the active material porosity enables an improvement in production quality.

[0066] It is further proposed to produce a battery cell winding comprising at least one battery electrode manufactured according to a manufacturing process as previously described, in particular a battery electrode in which the active material porosity is known. A manufacturing process is proposed for producing such a battery cell winding, in which at least one such battery electrode with known active material porosity is provided, and in which a battery cell separator is further provided. For the purposes of the invention, such a battery cell separator is understood to be a film-like element that is used in the battery cell winding together with at least two battery electrodes.The basic structure of a battery cell winding as such is not affected by the present invention; however, the present invention enables the targeted assignment / selection of elements, in particular at least one separator, suitable – especially with regard to the active material porosity and the porosity of the separator – to at least one battery electrode, and thus a high performance of the manufactured battery cell can be achieved with this assignment, or rather, good operating characteristics can be achieved.

[0067] As explained, such a battery cell separator is designed to be assembled into a battery cell winding with at least two battery electrodes, the active material porosity of at least one of which is known. Such a battery cell winding therefore comprises at least two battery electrodes and a battery cell separator.

[0068] Such a battery cell separator has pores, particularly for receiving an electrolyte, known as separator pores. These separator pores are completely or partially surrounded by non-porous separator material, of which this battery cell separator therefore consists at least substantially. Furthermore, the invention proposes determining the composition of this battery cell separator with respect to these separator pores and the surrounding non-porous separator material before assembling the battery cell winding, or in other words, determining the so-called battery cell separator porosity before assembling the battery cell winding. In this context, battery cell separator porosity refers to the porosity profile along the longitudinal axis of this battery cell separator, which is preferably determined in the same manner as for the battery electrode. 24-0119 PIF

[0069] 15

[0070] To determine battery cell separator porosity, it is proposed to measure the proportion of separator pores and the proportion of pore-free separator material at a first location along the longitudinal direction of the battery cell separator and at a multitude of other locations, particularly those differing in the longitudinal direction of the battery cell separator. Accordingly, when measuring battery cell separator porosity at a multitude of different locations along the longitudinal direction of the battery cell separator, its composition is examined with respect to the battery cell separator pores and the surrounding pore-free separator material. This yields a separator porosity distribution along the longitudinal direction, the so-called battery cell separator porosity.In particular, if the battery cell separator porosity is known, an assignment rule for matching a battery electrode with known active material porosity to a battery cell separator with known battery cell separator porosity can be obtained – especially from an analysis of manufactured battery cells – whereby this assignment rule takes at least one of these porosities into account.

[0071] In a preferred embodiment of the invention, a method for manufacturing a battery cell winding is proposed, in which at least one, preferably two, and preferably more battery electrodes, each with an active material porosity known at least partially, and at least one battery cell separator, the porosity of which is known at least partially in its longitudinal direction, are assembled into a battery cell winding using such an allocation rule. Preferably, the battery cell separator is aligned longitudinally with the at least one battery electrode according to this allocation rule. In particular, these components are aligned longitudinally with respect to each other so that this allocation rule is fulfilled, taking into account the active material porosity and the battery cell separator porosity.In particular, such a manufacturing process enables early detection of the properties of the battery cell winding, thereby achieving high production efficiency.

[0072] Furthermore, a battery cell is proposed which has at least one battery electrode for which at least one active material porosity is known, or a battery cell with a battery cell winding manufactured according to one of the previously described methods. Particularly for such a battery cell, good early detection of its operating characteristics is possible, so that the number of battery cells that do not meet a requirement profile can be kept low, or such battery cells can be avoided altogether, thus achieving high production efficiency. 24-0119 PIF

[0073] 16

[0074] The following section explains individual features of the invention and embodiments thereof in more detail with reference to the at least partially schematic figures; combinations of features other than those shown are also fundamentally possible to achieve an embodiment according to the invention, as shown:

[0075] Fig. 1: Schematic partial process for manufacturing a battery electrode and determining its active material porosity,

[0076] Fig. 2: Schematic partial process for manufacturing a battery electrode and determining its active material porosity in a further embodiment,

[0077] Fig. 3: Schematic device for measuring the active material porosity of a double-sided coated battery electrode,

[0078] Fig. 4: Schematic device for measuring the active material porosity of a single-sided coated battery electrode,

[0079] Fig. 5: Schematic matching of a battery electrode with a battery cell separator based on an assignment rule based on their porosities.

[0080] Figure 1 shows a highly schematic system for manufacturing a battery electrode, including the measurement of its active material porosity. The process performed by this system involves the following steps:

[0081] - Providing the battery electrode carrier film 1 in the form of a strip which has a carrier film width in the carrier film width direction and a carrier film length in a carrier film longitudinal direction,

[0082] - Transporting the battery electrode carrier film 1 in the direction of the carrier film longitudinal direction, i.e., the so-called production direction 2, through the system,

[0083] - one-sided application of the battery electrode active material 3 onto the battery electrode carrier film 1 by means of a slot nozzle device 4 to produce a coated battery electrode carrier film 8,

[0084] - Determining the composition of the applied battery electrode active material with respect to the proportion of battery electrode active material pores and the proportion of pore-free active material, so-called active material porosity, wherein the active material porosity is measured at a first location 6 in the longitudinal direction 5 of the carrier film and at a plurality of further locations 7 which differ from this first location and 24-0119 PIF

[0085] 17, whereby the active material porosity is measured at a large number of different locations on the battery electrode in the longitudinal direction of the carrier film.

[0086] Figure 1 shows that, insofar as the active material porosity is measured at this first location with respect to the coated battery electrode carrier film, this first location moves through the production plant during transport in production direction 2. To carry out the proposed process, the plant includes a slot nozzle device 4, a calendering device 9 for mechanical compaction, and a drying device 10 for applying heat. Devices 11, 12a, and 12b for measuring the active material porosity are provided downstream of these devices 4, 9, and 10, respectively. The first of these devices 11 is designed as a combined device 11, which measures the thickness of the battery electrode active material layer by means of a contact sensor 14 and the morphology of the active material pores by means of an X-ray device.The second of these three facilities, 12a, is configured as a computed tomography facility, 12a, and the third is also configured as a computed tomography facility, 12b. If the active material porosity is recorded simultaneously using these three facilities, 11, 12a, and 12b, it will be recorded at three different locations.

[0087] Figure 2 shows the system known from Figure 1 for carrying out the proposed method, in which a magnetic resonance imaging device 13a, 13b, 13c is arranged after the slot nozzle device 4, after the calendering device 9 and after the drying device 10 to detect the active material porosity.

[0088] Figure 3 shows a computed tomography system, such as the computed tomography system 12a and 12b shown in Figure 1, for determining the active material porosity, i.e., for determining the morphology of the active material pores and the active material layer thickness at a location on the battery electrode. A double-sided coated battery electrode is shown; the battery electrode carrier film 1 thus has a first battery electrode active material layer 17 and a second battery electrode active material layer 18, which at least substantially cover the battery electrode carrier film 1 in its width direction 21. The battery electrode is transported in the production direction 2 through the computed tomography system shown, in which the active material porosity of these battery electrode active material layers is determined by means of the imaging method.The first and second battery electrode active material layers 17, 18 each have a battery electrode active material layer thickness 19, 20. To detect the active material porosity, an emitter 16, which emits a measuring signal, is used.

[0089] The emitter 16 emits a signal 18 times, and a detector 15, which records the response to this measurement signal, is provided. This emitter 16 and this detector 15 are moved around the battery electrode to acquire a complete picture of it, in particular to determine its active material porosity for both the first battery electrode active material layer 17 and the second battery electrode active material layer 18.

[0090] Figure 4 shows a combined X-ray geometry measuring device 11a, which uses a non-contact sensor 14.1 to detect the layer thickness 24 of the battery electrode active material applied to one side of the battery electrode carrier film 1 as a battery electrode active material layer 25, while the latter is transported in the production direction 2. The battery electrode carrier film 1, and with it the battery electrode active material layer, extends in the width direction 21. The X-ray device 14.2 enables the detection of the active material pores contained in the battery electrode active material layer 25, and the non-contact sensor 14.1 can detect not only the layer thickness 24 but also the width direction 21 of the battery electrode active material layer 25.

[0091] Figure 5 shows a highly schematic representation of the alignment of a battery electrode with a known active material porosity 26, or one determined by the proposed method, to a separator with a known separator porosity 27, or one determined by the proposed method, in the longitudinal direction 5 of the carrier film. This is to be understood as a purely schematic representation. The battery electrode with known active material porosity 26 is aligned with the separator with known separator porosity 27 in this longitudinal direction 5, i.e., by means of the alignment rule 28, so that a matching preferred for the operating characteristics is achieved. Figure 5a) shows an arbitrary arrangement, whereas Figure 5b) shows an alignment with a preferred matching.The allocation rule can be determined experimentally or by calculation, such as a simulation of the preferred properties of the battery cell to be manufactured, depending on the application of the battery cell or other boundary conditions.

Claims

-0119 PIF 19 Claims 1. A method for producing a battery electrode intended for use in an electrochemical battery cell, wherein the battery electrode carrier film (1) comprises a battery electrode support film (1) and wherein this battery electrode support film (1) is coated on at least one side with a battery electrode active material (3), so-called battery electrode active material layer (17), and wherein this battery electrode active material layer (17) has so-called battery electrode active material pores which are completely or partially surrounded by pore-free active material, wherein this method comprises the following steps, - Providing the battery electrode carrier film (1) in the form of a strip which has a carrier film width in a carrier film width direction (21) and a carrier film length in a carrier film longitudinal direction, - Transporting the battery electrode carrier film in the direction of the carrier film longitudinal direction (5), so-called production direction, - at least one-sided application of the battery electrode active material (3) to the battery electrode carrier film (1) in order to produce a coated battery electrode carrier film which covers the carrier film (1) at least section by section in the carrier film width and the carrier film length, - Determining the composition of the applied battery electrode active material with respect to the proportion of battery electrode active material pores and the proportion of pore-free active material, so-called active material porosity, wherein the active material porosity is determined at a first location in the longitudinal direction of the carrier film (5) and at a plurality of other locations which deviate from this first location and wherein the active material porosity is thus determined at a plurality of different locations of the battery electrode in the longitudinal direction of the carrier film (5).

2. Method for producing a battery electrode according to claim 1, characterized in that, in order to determine the active material porosity, the morphology of the active material pores and at least the thickness of the at least one battery electrode active material layer (17) applied to the carrier film (1), so-called active material layer thickness (24), are recorded at this first location and at at least one of these further locations and -0119 PIF 20 that an X-ray device (14.2) is provided to detect this morphology of the active material pores and that a contact or non-contact geometry measuring device (11, 11a) is provided to detect the active material layer thickness and that an active material porosity distribution in the longitudinal direction of the carrier film is thereby determined.

3. Method for producing a battery electrode according to one of the preceding claims, characterized in that, to determine the active material porosity, i.e., to determine the morphology of the active material pores and at least additionally also the active material layer thickness (24) at this first location and at least one of these further locations, a radiological imaging method, such as computed tomography, is used, and that at least one cross-sectional image of the battery electrode active material layer (17) is thereby generated at each of these locations, and that an active material porosity distribution in the longitudinal direction (5) of the carrier film is thereby determined.

4. A method for producing a battery electrode according to one of the preceding claims, characterized in that, in order to determine the active material porosity, i.e., to determine the morphology of the active material pores and at least additionally also the active material layer thickness at this first location and at at least one of these further locations, an imaging method based on the application of magnetic fields and radio waves, such as magnetic resonance imaging, is used, by means of which at least one cross-sectional image of the battery electrode active material layer is obtained. (17) is generated at each of these locations and that an active material porosity distribution in the longitudinal direction of the carrier film is thereby determined.

5. Method for producing a battery electrode according to one of the preceding claims, characterized in that, in the production direction, after the application of the battery electrode active material as a battery electrode active material layer (17), this layer is dried, and that the battery electrode active material layer (17) is mechanically compacted after this drying, and that, in order to determine the active material porosity, the additives are added at least once more. -0119 PIF 21. The composition of the applied battery electrode active material with respect to the proportion of battery electrode active material pores and the proportion of pore-free active material is determined at at least two different locations of the battery electrode in the longitudinal direction of the carrier film after this drying, so that an active material porosity distribution in the longitudinal direction of the carrier film is determined before and after this drying.

6. A method for producing a battery electrode according to one of the preceding claims, characterized in that, in the production direction, after the application of the battery electrode active material as a battery electrode active material layer (17), this layer is dried, and that the battery electrode active material layer (17) is mechanically compacted after this drying, and that, in order to determine the active material porosity, the composition of the applied battery electrode active material with respect to the proportion of battery electrode active material pores and the proportion of pore-free active material is determined at least once more at at least two different locations of the battery electrode in the longitudinal direction (5) of the carrier film, and that an active material porosity distribution in the longitudinal direction (5) of the carrier film is thereby determined before and after this mechanical compaction.

7. A method for manufacturing a battery cell winding comprising at least one battery electrode manufactured according to a manufacturing method as defined in one of the preceding claims, wherein a battery cell separator is provided during the manufacturing of the battery cell winding, wherein the battery cell separator is assembled with at least two battery electrodes to form a battery cell winding, and wherein the battery cell separator has pores, so-called separator pores, which are completely or partially surrounded by non-porous separator material, and wherein a battery cell separator porosity is determined prior to this assembly of the battery cell winding, wherein, to determine the battery cell separator porosity, the proportion of separator pores and the proportion of non-porous separator material at a first location in a longitudinal direction of the battery cell separator and at a plurality of locations deviating from this first location are determined.further location is recorded, thereby recording the battery cell separator porosity at a large number of different locations of the battery cell separator in the longitudinal direction of the battery cell separator, -0119 PIF 22, and wherein a separator porosity distribution in its longitudinal direction is thus determined.

8. Method for producing a battery cell winding according to claim 7, wherein for the at least one battery electrode, which is produced according to a method according to one of claims 1 to 6, the active material porosity in the longitudinal direction of the carrier film is known, at least section by section, and wherein for the battery cell separator the battery cell separator porosity in its longitudinal direction is known, at least section by section, and wherein an assignment rule is specified according to which the battery cell separator is aligned longitudinally on this battery cell electrode, wherein the assignment rule takes into account both the active material porosity distribution and the separator porosity distribution.

9. Electrochemical battery cell with a battery electrode manufactured according to a method according to any one of claims 1 to 6 or with a battery cell winding manufactured according to a method according to any one of claims 7 or 8.

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