Battery cell electrode manufacturing method, battery cell electrode and battery cell having a battery cell electrode

Abstract

The invention relates to a battery cell electrode manufacturing method for manufacturing a battery cell electrode for a lithium-ion battery cell, wherein the battery cell electrode has an electrode carrier film and wherein an electrode active material is applied to said carrier film, and wherein said electrode active material is inhomogeneous and has so-called active material pores which are surrounded by electrode active material, comprising the steps of: - providing the electrode carrier film; - applying the electrode active material to the electrode carrier film in an electrode longitudinal direction; - determining the amount of electrode active material applied to a first electrode longitudinal portion; - ascertaining a first electrode layer thickness for said first electrode longitudinal portion as a function of the previously determined amount of electrode active material applied; - compacting the electrode active material in said first electrode longitudinal portion to the ascertained electrode layer thickness; - determining the amount of electrode active material applied to at least one other electrode longitudinal portion; - ascertaining another electrode layer thickness for said at least one other electrode longitudinal portion as a function of the previously determined amount of electrode active material applied thereto; - compacting the electrode active material in said at least one other electrode longitudinal portion for the ascertained other electrode layer thickness; - wherein the first electrode layer thickness differs from the at least one other electrode layer thickness.

Description

[0001] 23-3117 PIF 1 Battery cell electrode manufacturing method, battery cell electrode, and battery cell with battery cell electrode. The invention relates to a method for manufacturing an electrode for a battery cell, a so-called battery cell electrode manufacturing method, a battery cell electrode, and a battery cell with such a battery cell electrode. DE 102021109630 A1 discloses a method for manufacturing a battery cell and a battery cell, wherein the manufacturing method is based on a constant layer thickness of the electrode. The invention is explained below using a manufacturing method for manufacturing lithium-ion round cells for the automotive sector, or lithium-ion battery cells for use in a high-voltage storage device of an automobile.This is not to be understood as a limitation of the invention to such an application. In a high-voltage storage system of a motor vehicle, so-called round cells are frequently used, which are designed as lithium-ion battery cells and have a cylindrical geometry. A large number of such cells are grouped and interconnected to form the so-called high-voltage storage system. A large number of process steps are necessary for the industrial production of these battery cells. The individual process steps, particularly in the manufacture of an electrode for a battery cell, can influence its operating characteristics and thus the entire high-voltage storage system. Two essential process steps in the manufacture of the so-called electrodes for the battery cell are the coating process, in which materials for the electrochemical operation of the battery cell are applied to a carrier film, and the calendering process.in which the applied electrode material is also geometrically shaped. The calendering process therefore includes a mechanical consolidation process, which is usually designed as a rolling process. During this consolidation process, the material applied to the carrier film is mechanically compressed to a predetermined layer thickness using a rolling device. The geometric shape of the material applied to the carrier film has a significant influence on the electrochemical properties of the battery storage cell, of which the coated carrier film becomes a component. In a round cell, the electrode is used to create a battery cell coil, a so-called Jelly-23-3117 PIF 2 Roll, which is inserted into a battery cell housing. It is known from the prior art to compress the material applied to the carrier film in such a way that, after compression, it is in the longitudinal direction of the electrode,has a constant layer thickness, it is ensured that a specific length of the coated carrier film is wound into a cell coil with a specific diameter, which fits into this battery cell housing. It is an object of the invention to provide a battery cell electrode manufacturing method by means of which a battery cell electrode is produced which contributes to improved operating behavior in a battery cell to be produced therewith, and further to provide a battery cell electrode with improved operating behavior and a battery cell having such a battery cell electrode. The stated object is achieved by a manufacturing method according to patent claim 1, a battery cell electrode according to patent claim 5, and by a battery cell according to claim 7. Preferred further developments are the subject matter of the dependent patent claims. A basic idea of ​​the invention isTo adjust the porosity of an electrode active material applied to the electrode carrier foil during the production of an electrode, in particular for a lithium-ion battery storage cell, to a predetermined porosity target value by means of mechanical compaction, in particular during so-called calendering. For this purpose, it is proposed to determine the porosity of the electrode active material applied to the electrode carrier foil and thus to assign the recorded porosity values ​​to electrode track sections in an electrode longitudinal direction. To determine the porosity, in particular, a recurring or continuous measurement, so-called inline measurement, of the amount of electrode active material applied to such a section is provided. In particular, such a measurement makes it possible to perform a porosity matching of the battery cell electrode to be produced for an electrode coil.in particular for a so-called jelly roll. The proposed measure enables an improvement in the operating properties, in particular the charging properties, of the battery cell electrode to be manufactured. The invention accordingly relates to a manufacturing method for producing an electrode for use in a battery cell, preferably a lithium-ion battery cell, which is referred to below as a battery cell. Such a battery cell has as its main components a positive electrode, so-called cathode, and a negative electrode, so-called anode, which are separated from each other by an insulating layer, the so-called separator. This separator prevents, especially above a certain temperature, the continuous migration of ions between this anode and this cathode.In particular, the separator prevents components from overheating. Furthermore, the separator enables an electric current to flow through its permselectivity, i.e., the property that allows the migration of current ions. Another function of the separator is the physical separation of the electrodes, i.e., the anode and the cathode, thus preventing random current flows and ultimately preventing a short circuit in the cell. The electrodes of the battery cell are coated with a so-called active material, or electrode active material, which is crucial for the electrochemical function of the battery cell. The invention can be applied regardless of the composition of this electrode active material. The proposed manufacturing method relates to individual manufacturing steps in the production of an electrode for a battery cell.This electrode comprises a so-called electrode carrier foil and an electrode active material applied to this electrode carrier foil. The composition of this active material is not the subject of the invention in detail, since the invention is applicable to a wide variety of such active materials. Furthermore, in a later manufacturing step, which is not the subject of the invention, the electrode active material is to be filled with and absorb a so-called electrolyte. The invention proposes a battery cell electrode manufacturing method for producing a battery cell electrode, in particular for a lithium-ion battery cell. Such a battery cell electrode comprises an electrode carrier foil. For the purposes of the invention, an electrode carrier foil is to be understood as a foil, preferably an electrically conductive foil, at least in layers, which has a low foil thickness.Wherein, in the sense of the invention, a low film thickness is understood to mean a thickness of less than 0.5 mm, preferably 0.1 mm or less. Further preferably, the carrier film is designed as a single- or multi-layer film, which preferably has a metallic layer or consists of a metallic layer. Such a metallic layer is preferably understood to mean a copper foil, which preferably has a film thickness of 10 micrometers or less, and further preferably, a metallic layer is also understood to mean an aluminum foil.which preferably has a foil thickness of 15 micrometers or less. Preferably, a copper foil has a foil thickness of 6 micrometers 23-3117 PIF 4, and more preferably, an aluminum foil has a foil thickness of 12 micrometers. Further preferably, this electrode carrier foil is designed as a type of strip and has a small electrode width compared to the electrode's longitudinal extent, and more preferably, this foil thickness is many times smaller than this longitudinal and this width. Further preferably, in the context of the invention, this is to be understood as meaning that the electrode's longitudinal extent is a multiple of the electrode width, and the electrode width is a multiple of the foil thickness. Further preferably, the electrode carrier foil is designed as a flexible foil,which can be wound up or unwound during the production of a lithium-ion battery storage cell. Such an electrode carrier foil is known as such from the prior art. It serves to hold the so-called electrode active material and to conduct electrical current to a pole of the lithium-ion battery cell or from such a pole to the electrode active material on the electrode carrier foil. The electrode active material is applied as an inhomogeneous material to the electrode carrier foil. Figuratively speaking, the applied electrode active material has pores, so-called active material pores, enclosed, i.e., areas,within which no electrode active material is present. The total volume of the layer of electrode active material applied to the electrode carrier foil is thus composed of the volume of the active material pores and the volume of the electrode active material without pores. Furthermore, these active material pores are regions enclosed in the electrode active material or largely enclosed regions, and the electrode active material is preferably an open-pored material. In particular, such active material pores in this manufacturing process are therefore air- or gas-filled regions in the electrode active material layer. The electrode active material is applied in a layer to this electrode carrier foil; this layer can also be referred to as the electrode active material layer, and this electrode active material layer is, at least essentially,formed from electrode active material and active material pores. In particular, in a battery cell electrode for a lithium-ion battery cell, the electrode active material is applied in an at least substantially uniform layer to this electrode carrier foil, wherein the electrode carrier foil may have one or two uncoated edge regions. The basis weight (g / cm²) of the applied electrode active material is, particularly for the same volume of applied electrode active material, a measure of the volume of active material pores contained in the electrode active material layer. For the same layer thickness of the applied electrode active material, a large volume of active material pores leads to a low basis weight, with otherwise identical parameters. The invention utilizes this finding in the formthat, particularly under otherwise constant boundary conditions and with a known basis weight of the applied electrode active material, the volume of the active material pores, and thus their proportion in the applied layer, can be influenced by a mechanical change in the layer thickness of the electrode active material, in particular a compaction of the applied electrode active material. In particular, this compaction is carried out during the so-called calendering process. In other words, such a change in the applied layer thickness of the electrode active material influences the proportion of active material pores present in this layer, or rather, their volume. Figuratively speaking, the volume occupied by the active material pores in a specific surface section of the coated electrode carrier film can be reduced bythat the layer thickness of the applied electrode active material layer is reduced by mechanically compacting this layer, in particular by a rolling process. When applying the electrode active material to the electrode carrier foil, it can happen, due to unavoidable deviations, that the volume fraction of active material pores varies from surface section to surface section in the longitudinal direction of the battery cell electrode. In particular, such a variance in the proportion of active material pores, or the volume occupied by them, occurs in the longitudinal direction of the electrode or the longitudinal extent of the electrode. The invention counteracts such a variance and, through the mechanical compaction of the applied electrode active material, reduces this variance by adapting the compaction to the proportion of active material pores.which are present in this longitudinal section. In particular, by reducing the variance in porosity, as proposed, such an inventive electrode can be designed for higher performance than an electrode known from the prior art, or, to put it another way, less "safety buffer" in the porosity is necessary for the proposed electrode than for a conventional electrode. Particularly in so-called high-energy cells with silicon-containing anodes, the porosity of the anode is a limiting factor for further increasing energy and influences the rapid charging capacity. With the proposed invention, an improvement in these properties can be achieved. However, the invention thus accepts a variance in the layer thickness of the applied electrode active material in this longitudinal direction of the electrode.This is because, qualitatively, areas of the electrode active material applied to the carrier foil with a low proportion of active material pores are less densified than areas with a high proportion of active material pores. The proposed battery cell electrode manufacturing method comprises the following steps: - Providing the electrode carrier foil, - Applying the electrode active material to the electrode carrier foil in at least one layer in the longitudinal direction of the electrode, - Determining the amount of electrode active material applied to a first longitudinal electrode section, - Determining a first electrode layer thickness for this first longitudinal electrode section as a function of the previously determined amount of applied electrode active material, - Compacting the electrode active material in this first longitudinal electrode section to the determined electrode layer thickness,- Determining the amount of electrode active material applied to at least one further electrode longitudinal section, - Determining a further electrode layer thickness for this at least one further electrode longitudinal section as a function of the previously determined amount of electrode active material applied thereto, - Compacting the electrode active material in this at least one further electrode longitudinal section to the further electrode layer thickness determined for the further electrode layer thickness,- wherein the first electrode layer thickness differs from the at least one further electrode layer thickness. In the proposed manufacturing method, the electrode carrier foil is coated with the electrode active material as a quasi-endless strip. The longitudinal direction of the quasi-endless electrode carrier foil is thus to be understood as the electrode longitudinal direction, and the electrode width direction extends transversely to this electrode longitudinal direction. Preferably, the uncoated electrode carrier foil is provided as a roll, wherein the wound length of the carrier foil is to be understood as quasi-endless within the meaning of the invention. For coating with electrode active material, the electrode carrier foil is unwound from this roll. When applying the electrode active material to the electrode carrier foil, this electrode active material is applied as a layer with a preferably in the electrode width direction,i.e., orthogonal to the longitudinal direction of the electrode, and further preferably also in the longitudinal direction of the electrode, in a layer thickness that is uniform in the longitudinal direction of the electrode. This application can be carried out in one or more layers; furthermore, a layer that is as geometrically uniform as possible is preferably applied to the electrode carrier foil, in particular, this layer has an at least substantially constant layer thickness in the longitudinal direction of the electrode and the electrode width direction. Further preferably, after coating with the electrode active material, the electrode carrier foil has at least one, preferably two, uncoated edge regions in the electrode width direction. In the manufacturing process explained, after or during the application of the electrode active material to the electrode carrier foil,the amount of electrode active material applied to a first longitudinal section of the electrode is determined. Such a determination can preferably be carried out directly, in particular by means of a weighing device, or indirectly by means of a method in which the coated carrier film is irradiated or irradiated through. It is important for the proposed method to determine the proportion of active material pores in the electrode active material layer. Preferably, the basis weight of the electrode active material applied to the electrode carrier film is continuously determined. Furthermore, a first electrode layer thickness for this first longitudinal section of the electrode is determined using the basis weight of the applied electrode active material and the geometric shape of the electrode active material layer at the point where its basis weight is known. This first electrode layer thickness is determined in such a way thatso that a proportion of active material pores in a predetermined range is achieved. This proportion of active material pores for this first longitudinal electrode section, preferably based on the volume of the applied layer of electrode active material, is preferably greater than 20%, preferably greater than 23%, and more preferably greater than 25%, and further less than 60%, preferably less than 40%, and more preferably less than 35%. 23-3117 PIF 8 In a further step, the electrode active material applied to the electrode carrier film in this first longitudinal electrode section is adjusted by mechanical compaction to the electrode layer thickness determined for this section. In particular, this compaction determines the proportion of active material pores in the first longitudinal electrode section, or the volume they occupy.set to a value from the preferred range. This proposed determination of the amount of electrode active material applied to the electrode carrier foil and determination of a layer thickness for the electrode active material, in particular the derivation of a proportion of active material pores, which in particular forms a basis for achieving a specific proportion of active material pores, is preferably continued continuously. In particular, such continuous application creates the possibility of setting an at least substantially constant proportion of active material pores in the electrode longitudinal device using the proposed manufacturing method, whereas the layer thickness of the electrode active material applied to the electrode carrier foil exhibits a certain variance after compaction. The proposed method thus contrasts with known manufacturing methods,in which the electrode active material applied to the electrode carrier foil is compressed to a layer thickness that is constant in the longitudinal direction. In any case, in the proposed manufacturing method, the amount of electrode active material applied to this further electrode longitudinal section is determined for at least one further electrode longitudinal section, which preferably has the same length as this first electrode longitudinal section. Furthermore, based on the previously explained criteria, in particular the applied amount of electrode active material and the proportion of active material pores accommodated therein, a layer thickness is determined for this further electrode longitudinal section, the so-called further electrode layer thickness. This further electrode layer thickness is preferably determined by the proposed manufacturing method in such a way thatthat the proportion of active material pores in this further electrode longitudinal section preferably corresponds to the proportion of active material pores in the first electrode longitudinal section. When a plurality of such further electrode longitudinal sections are arranged in a row, a battery cell electrode with constant porosity (proportion of active material pores in the electrode active material layer) can be manufactured in the electrode longitudinal direction. Furthermore, after determining this further electrode layer thickness for this further electrode longitudinal section, the 23-3117 PIF 9 electrode active material applied in the further electrode longitudinal section is adjusted or compacted by means of mechanical compaction to the further electrode layer thickness calculated for this longitudinal section, and thus the proportion of active material pores in this first and this at least one further electrode longitudinal section is, at least substantially,set to the same volume fraction, whereby the geometric layer thicknesses of the electrode active material in the first and this at least one further electrode longitudinal section can differ from each other. In particular, the layer thickness of the applied electrode active material in the first electrode longitudinal section differs from the layer thickness of the electrode active material in this at least one further electrode longitudinal section, whereas the proportion of active material pores in this first and this at least one further electrode longitudinal section is at least substantially the same, or in other words, the essential control parameter when compacting the electrode active material layer is preferably not a uniform layer thickness in the electrode longitudinal direction, but the volume fraction of the active material pores in this layer, which is adjusted to a constant,a predetermined value is set. Investigations have shown that with such a manufacturing process, battery cell electrodes with particularly preferred electrochemical properties can be produced; in particular, the charging capacity of a battery cell in which such a battery electrode is used can be positively influenced. Preferably, the first or such a further electrode longitudinal section can have a length of a few 1 / 1000 mm up to several centimeters. In a preferred embodiment of the invention, a plurality of further electrode layer thicknesses are determined; preferably, this determination of the electrode layer thicknesses is carried out continuously. Furthermore, in particular through the mechanical compaction of the applied electrode active material layer,that the volume of the active material pores in a plurality of these electrode longitudinal sections does not deviate from one another by more than 20%, preferably not more than 10%, preferably not more than 5%, preferably not more than 2%, and particularly preferably not more than 1%. In particular, a uniform volume fraction of the active material pores in the electrode longitudinal direction leads to a battery cell electrode with good electrochemical properties. 23-3117 PIF 10 In a preferred embodiment of the proposed manufacturing method, the volume of the active material pores in this first and preferably a plurality and particularly preferably in all further electrode longitudinal sections, in particular through this compaction, lies within a predetermined active material pore volume range. This target value is preferably predetermined for this volume fraction and is preferably in a range,which is greater than 20% and which is less than 60%. This range is preferably greater than 20%, preferably greater than 23%, and particularly preferably greater than 25%, and further preferably the range is less than 60%, preferably less than 40%, and particularly preferably less than 35%. In particular, with a proportion of active material pores in the aforementioned range, particularly positive properties for the battery electrode are obtained. The aforementioned condition preferably applies at least to an extension in the longitudinal direction of the electrode, as provided for a single battery cell, whereby different electrode lengths can result for battery cells, in particular of different types or types. In a preferred embodiment of the proposed manufacturing method, the electrode layer thickness in the longitudinal direction of the electrode, in particular after compaction thereof by the proposed manufacturing method,a function of the amount of electrode active material applied in this area, in particular the basis weight of the applied electrode active material in this section. Furthermore, a battery cell electrode is proposed. This battery cell electrode is preferably produced using the previously explained manufacturing method, and further preferably, the battery cell electrode has the properties explained below. The proposed battery cell electrode is designed as a lithium-ion battery cell electrode or at least provided as a battery cell electrode for a lithium-ion battery cell. The proposed battery cell electrode has an electrode carrier foil, on which the electrode active material is applied in the electrode active material layer. The electrode carrier foil is, as explained, particularly for electrically contacting the electrode active material.i.e., for conducting electrical current in the battery cell. The electrode active material is designed as an inhomogeneous material and has so-called active material pores, which are essentially to be understood as a cavity or cavities surrounded by electrode active material. In the first electrode longitudinal section, which can have a predetermined length, the 23-3117 PIF 11 active material pores occupy a first active material pore volume. The total volume of the layer applied to the electrode carrier foil is therefore composed of the volume of the electrode active material (without active material pores) and the volume of the active material pores contained therein. Figuratively speaking, a high proportion of active material pores for the same volume of the electrode active material layer leads to a lower weight of the applied layer.In particular, by means of this connection, the proportion of active material pores contained therein can be determined by determining the weight of the applied electrode active material layer on the electrode carrier foil. Furthermore, the active material pores occupy a further active material pore volume in at least one further electrode longitudinal section. Furthermore, the battery cell electrode is manufactured such that this first and this further active material pore volume, based on the volume, differ from one another by less than 10%, preferably by less than 5%, and more preferably by less than 1%. Preferably, the first and the second electrode longitudinal section have, at least substantially,the same length. Preferably, the length for this first and this at least one further electrode longitudinal section is in a range between a few 1 / 1000 mm and a few centimeters. Further preferably, the battery cell electrode is manufactured such that, relative to an extension in the electrode longitudinal direction for a so-called cell coil for a battery cell, it has at least substantially a constant proportion, relative to the volume, of active material pores in the electrode active material applied to the electrode carrier foil. In particular, with such a battery cell electrode, preferred electrochemical properties can be achieved, in particular for the charging capacity of a battery cell with such a battery cell electrode. In a preferred embodiment, the battery cell electrode has a plurality of further electrode longitudinal sections,wherein the active material pores in these longitudinal electrode sections each occupy further active material pore volumes. The first and this plurality of further active material pore volumes preferably differ from each other by less than 10%, preferably by less than 5%, and particularly preferably by less than 1%. 23-3117 PIF 12 Furthermore, a lithium-ion battery cell is proposed, which has an electrode coil having at least one battery cell electrode of the previously explained design. Individual features and preferred developments of the invention are explained in more detail below with reference to the figures, at least partially in a highly simplified form. It is further pointed out that combinations of features other than those shown are also possible. It shows: Fig. 1: Schematic sequence of a battery cell production including a battery cell electrode production method,Fig. 2: Schematic sequence of the proposed battery cell electrode manufacturing process. Fig. 3: Schematic control process for the proposed battery cell electrode manufacturing process. Fig. 4: Schematic winding process for the proposed battery cell electrode manufacturing process. Fig. 5: Highly schematic representation of a calendered battery cell electrode a) according to the prior art and b) according to the proposed manufacturing process. Fig. 1 shows a schematic flow chart for a manufacturing process for a lithium-ion battery cell.as is known from the prior art and as this also forms the starting point for the proposed battery cell electrode manufacturing process. During mixing 100 of the electrode active material, the electrode active material is mixed together from its individual components for further processing. The electrode carrier film is then provided 101 and coated as evenly as possible with the mixed electrode active material. During drying 102 of the electrode active material, moisture is removed from it. After drying 102, the applied layer of electrode active material is mechanically compacted by means of a rolling process 103 and brought to a constant layer thickness, so-called calendering. Next, the electrode carrier film coated with electrode active material is cut to size in a cutting process 104 and separated 105. After separation 105, the produced battery cell electrodes,In particular, a cathode and an anode are wound into a battery cell coil, a so-called jelly roll. After winding 106, the battery cell coil is inserted into a battery cell housing 107. The battery cell housing with the battery cell coil is then filled with an electrolyte and closed 108. For forming 109, the manufactured battery cell is charged or discharged for the first time. The proposed invention is based in particular on the steps for manufacturing the battery cell electrode in order to achieve improved operating behavior of the manufactured battery cell. Fig. 2 shows a schematic representation of the proposed battery cell electrode manufacturing process. The proposed manufacturing process can be divided into two main processes: A, the determination of the applied electrode active material, and B, the derivation of the length of the manufactured battery cell electrode.These two steps aim to achieve a constant porosity of the manufactured battery cell electrode over its length, whereby the battery cell electrode is rolled up in its longitudinal direction, i.e., the longitudinal extension of the electrode, to form the battery cell coil, and the width of the battery cell electrode forms the height of this battery cell coil. The process steps shown in Figure 2 can be integrated into the sequence shown in Figure 1, or replace the corresponding process steps there. In contrast to the known mechanical compaction by the rolling process 103 (see Figure 1), in the proposed battery cell manufacturing process, the basis weight of the electrode active material applied to the electrode carrier foil is continuously determined and, based on the weight of the layer of electrode active material applied to the carrier foil, as well as its geometric shape,The volume of the active material pores contained in this layer, known as porosity, can be deduced. The compaction of the applied electrode active material is then controlled according to the proposed manufacturing process in such a way that the proportion of active material pores, particularly in the longitudinal direction of the electrode, is kept constant, or within a narrow range of values. This is achieved by the new mechanical compaction 203. Unlike in the prior art, the control variable during compaction, known as clandering, of the electrode active material applied to the carrier film is not the constant layer thickness, but rather a variable layer thickness results from the new mechanical compaction 203.which leads to a constant proportion of active material pores in the longitudinal direction of the electrode. Figure 3 shows a schematic flow chart for the control process and key influencing parameters of this process for achieving a constant porosity (proportion of active material pores in the applied layer of electrode active material). In step 101, the uncoated electrode carrier foil is provided, the electrode active material is applied to it as an electrode active material layer using a slot die 3, resulting in the coated electrode carrier foil. The electrode carrier foil is then drawn as a virtually endless strip beneath the slot die 3, i.e., in the longitudinal direction of the electrode.and fed to the further process steps as a coated electrode carrier foil 2. The determination 301 of the amount of electrode active material applied to the electrode carrier foil can be carried out by means of a continuous weighing process; in the example shown, an applied amount of electrode active material of 10 mg / cm² is determined. From this applied amount, the porosity of the electrode (PorosityElectrode) is determined 302 using the given relationships. Furthermore, the layer thickness of the applied electrode active material can also be determined from the given relationships, so that a constant porosity of this applied electrode active material results in the longitudinal direction of the electrode after mechanical compaction 203. In this case, the coated electrode carrier foil 2, in particular the electrode active material applied thereto,mechanically compacted using the proposed compaction process 203 such that a coated electrode carrier foil with a constant porosity 4, relative to the applied electrode active material, is created as a result of the mechanical compaction process 203. PorosityElectrode represents the porosity of the applied electrode active material, and VolumeCoat represents the volume of the applied layer of electrode active material before compaction. Geometrically, this volume can be described by the applied layer thickness (electrode active material), the width of this applied layer in the electrode width direction, and the length of the first or at least one further electrode longitudinal section. AreaElectrode indicates the area coated on the electrode carrier foil for the respective longitudinal section.i.e., the extent of such a section in the electrode longitudinal direction (first electrode longitudinal section or this at least one further electrode longitudinal section) and the extent of the applied layer of electrode active material in the electrode width direction. Thickness, Foil indicates the layer thickness of the electrode carrier foil. Mass coat represents the mass of electrode active material applied in the respective electrode longitudinal section. 23-3117 PIF 15 Mass Foilrepresents the mass of the electrode carrier foil in the respective longitudinal section of the electrode. MassElectrode indicates the mass determined by weighing the respective longitudinal section of the electrode. Volumex indicates the volume of a specific portion of a substance contained in the electrode active material with the portionx, and Densityx indicates the density of this substance. The sum of all substances contained in the electrode active material with their respective portions describes the total mass of the applied electrode active material, or enables the density (densityx) of the substances. Using the relationships outlined above, the layer thickness of the electrode active material applied to the electrode carrier foil is determined in such a way that it is ensured that the porosity of this material, i.e., the electrode active material layer, remains constant after mechanical compaction.Figure 4 shows method B for deriving the length of the manufactured battery cell electrode. The layer thickness set during mechanical compaction 203, which results from setting the constant porosity in the longitudinal direction of the electrode, is taken into account in order to achieve a target diameter during the production of the electrode coil that can still be inserted into the housing of the battery cell to be produced. Accordingly, the length of the electrodes is varied during production so that a constant diameter is achieved for the battery cell coil to be produced. Figure 5 shows a comparison of a battery cell electrode produced according to the prior art (see Fig. 5 a) and a battery cell electrode produced according to the proposed production method (see Fig. 5 b).Figure 5a shows a longitudinal sectional view of a battery cell electrode with an electrode carrier film 1. This is coated with electrode active material which is compressed to a constant layer thickness 6 in the electrode longitudinal direction 8. The battery cell electrode extends orthogonally to the electrode longitudinal direction 8 or the electrode longitudinal extent in the electrode width direction 16 or the electrode width extent. In contrast to the constant layer thickness of the applied electrode active material 9, which has a porosity varying in the electrode longitudinal direction 8 (volume fraction of the active material pores in the total volume of the applied electrode active material), Figure 5b shows a battery cell electrode produced according to the proposed manufacturing method in a longitudinal sectional view. The first electrode longitudinal section 6 and the second electrode longitudinal section 7 are shown as examples.The first longitudinal electrode section 6 has the first longitudinal extension 12, and the further longitudinal electrode section 7 has the further longitudinal extension 13; these sections are of equal size. The applied electrode active material has a constant porosity due to the different layer thicknesses 10, 11 in these longitudinal sections. Such a battery cell electrode configuration has improved operating characteristics compared to a battery cell electrode known from the prior art, as shown in Figure 5a) in a longitudinal section.

[0002] 23-3117 PIF 17 List of reference symbols: 1 Electrode carrier film 2 Coated electrode carrier film (uncalendered) 3 Slot nozzle for applying electrode active material 4 Coated electrode carrier film with constant porosity (calendered using the proposed manufacturing process) 5 Coated electrode carrier film with constant layer thickness (calendered according to the prior art) 6 First electrode longitudinal section 7 Further electrode longitudinal section 8 Electrode longitudinal direction 9 Layer thickness of the applied electrode active material for 5 10 Layer thickness of the applied electrode active material for 6 11 Layer thickness of the applied electrode active material for 7 12 Longitudinal extension of the first electrode longitudinal section 13 Longitudinal extension of the second electrode longitudinal section 14 Electrode active material with variable porosity in 8 15 Electrode active material with constant porosity in 8 16 electrode width direction

Claims

23-3117 PIF 18 Claims 1. Battery cell electrode manufacturing method for producing a battery cell electrode for a lithium-ion battery cell, wherein the battery cell electrode has an electrode carrier foil and wherein an electrode active material is applied to this carrier foil and wherein this electrode active material is inhomogeneous and has so-called active material pores which are surrounded by electrode active material, comprising the steps of: - providing the electrode carrier foil, - applying the electrode active material to the electrode carrier foil in an electrode longitudinal direction, - determining the amount of electrode active material applied to a first electrode longitudinal section, - determining a first electrode layer thickness for this first electrode longitudinal section as a function of the previously determined amount of applied electrode active material,- compacting the electrode active material in this first electrode longitudinal section to the determined electrode layer thickness, - determining the amount of electrode active material applied to at least one further electrode longitudinal section, - determining a further electrode layer thickness for this at least one further electrode longitudinal section as a function of the previously determined amount of electrode active material applied thereto, - compacting the electrode active material in this at least one further electrode longitudinal section to the determined further electrode layer thickness, - wherein the first electrode layer thickness differs from the at least one further electrode layer thickness.

2. Battery cell electrode manufacturing method according to claim 1, characterized in that a plurality of further electrode layer thicknesses are determined,that the volume of the active material pores in a plurality of these electrode longitudinal sections does not deviate from each other by more than X%. 23-3117 PIF 19 3. Battery cell electrode manufacturing method according to one of the preceding claims, characterized in that the volume of the active material pores in this first and all further electrode longitudinal sections, as a result of this compaction, lies within a predetermined active material pore volume range, which is greater than X volume % and which is smaller than Y volume %.

4. Battery cell electrode manufacturing method according to claim 1, characterized in that the electrode layer thickness in the longitudinal direction of the electrode is a function of the amount of electrode active material applied in this region. 5.Battery cell electrode for a lithium-ion battery cell, wherein the battery cell electrode has an electrode carrier foil and wherein an electrode active material is applied to this carrier foil, and wherein this electrode active material is inhomogeneous and has so-called active material pores which are surrounded by electrode active material, wherein in a first electrode longitudinal section the active material pores occupy a first active material pore volume and wherein in a further electrode longitudinal section the active material pores occupy a further active material pore volume, and wherein the first and this further active material pore volume differ from one another by less than 5% based on the volume. 6.Battery cell electrode for a lithium-ion battery cell according to claim 5, characterized in that it has a plurality of further electrode longitudinal sections, and the active material pores in these electrode longitudinal sections each occupy further active material pore volumes, and wherein the first and this plurality of further active material pore volumes each differ from one another by less than 5%.

7. Lithium-ion battery cell with an electrode coil, characterized in that the electrode coil has a battery cell electrode according to one of claims 5 or 6.

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