Method for filling a battery cell

Abstract

The invention relates to a method for filling a battery cell, in particular a lithium-ion battery cell, with an electrolyte, the method comprising: dry-coating (S10) an electrode for a battery cell; preparing (S20) the electrode for filling with an electrolyte; and filling (S30) the electrode with an electrolyte, wherein the filling takes place at a filling pressure of at least 4 bar.

Description

[0001] 23-2686

[0002] Method for filling a battery cell

[0003] The present invention relates to a method for manufacturing a battery cell, in particular for filling the electrolyte of a battery cell, more particularly a battery cell manufactured by means of the method, and a vehicle having a corresponding battery cell.

[0004] It is an object of the invention to further improve and / or accelerate, in particular, the filling of a battery cell.

[0005] The solution to this problem is achieved according to the teaching of the independent claims. Various embodiments and developments of the invention are the subject of the dependent claims.

[0006] According to one embodiment of the present invention, a method for electrolytic filling of a battery cell, particularly a lithium-ion battery cell, is provided. In one embodiment, the method includes dry-coating an electrode of a battery cell. In one embodiment, the method includes preparing the, particularly dry-coated, electrode for filling with an electrolyte. In one embodiment, the method includes filling the prepared electrode with the electrolyte. In one embodiment, the filling has a filling pressure of at least 4 bar, particularly, at least substantially, over a partial period of the filling and / or over the, at least substantially, entire period of the filling.In one embodiment, the filling has a filling pressure of at least 4 bar, or at least 5 bar, or at least 6 bar, or at least 7 bar, or at least 8 bar, or at least 9 bar, or at least 10 bar, or at least 15 bar, or at least 17.5 bar, or at least 20 bar and / or at most 30 bar, or at most 25 bar, or at most 20 bar. In one embodiment, the preparation involves winding the dry-coated electrode, particularly with a separator, in particular such that a (usually referred to as) jelly roll (form) is formed.

[0007] As used herein, the term "dry coating" is to be understood in particular as an at least substantially solvent-free coating process for producing electrodes of energy storage cells. In particular, in one embodiment, the coating material is an electrochemically active material and, in 23-2686

[0008] one embodiment, in particular at least, a fibrillating material, in particular a binder, thereon.

[0009] The term "filling with a filling pressure of at least x bar", as used herein, is to be understood in particular as a filling that, in particular at least, temporarily maintains a filling pressure of x bar, in particular until a (in particular predetermined) dosage of the electrolyte is, at least substantially, completed or is being completed.

[0010] Advantageously, in one embodiment, this enables the filling to be carried out more quickly, in particular more quickly than in comparison with a wet-coated electrode. Furthermore, advantageously, in one embodiment, in particular over a shorter process time, the production costs of battery cells can be reduced, in particular the time used by a production employee for the production of the battery cells. In one embodiment, a filling time, in particular for standard sizes of battery cells, in particular for vehicles, can be reduced to less than 5 minutes, in particular to less than 3 minutes, and even more particularly to less than 2 minutes.

[0011] In one embodiment, the method temporarily involves filling with a filling pressure described herein or by means of a filling pressure described herein, particularly over a predetermined period, more particularly based on a filling quantity or dosing quantity for the filling. In one embodiment, the filling pressure is based on a compaction of the electrode. In one embodiment, preparing the filling includes a step of detecting a compaction of the electrode.

[0012] Advantageously, in one embodiment, this can enable the filling to be carried out more quickly, particularly enabling costs to be saved, particularly compared to wet-coated electrodes and / or electrodes with an unsuitable and / or different porosity.

[0013] In one embodiment, preparing involves adjusting, in particular compressing, the (dry) coating of the electrode, in particular such that the resulting electrode and / or the prepared electrode has a density of 1.6 g / cm 3 or 1.5 g / cm 3 , in particular 1.4 g / cm 3 , in particular less than 1.5 g / cm 3 has. 23 - 2686

[0014] Advantageously, in one embodiment, this can enable an infiltration rate (gs -05 ) of equal to or more than 1.5 gs -05 to be achieved or is achieved, in particular more than 2.5 gs -05 , or more than 3.0 gs -05 . The infiltration rate, in one embodiment, describes the rate at which electrolyte is dosed into the electrode or can be dosed. This quantity, in one embodiment, is independent of the total volume of the electrode or the (battery) cell:

[0015] The term "infiltration rate" as used herein shall preferably be understood as in accordance with the following calculation method: In one embodiment, the empty cell volume of the electrode, particularly when, in one embodiment, the electrode was evacuated before filling, is filled at least substantially immediately after electrolyte dosing. This corresponds in one embodiment to the third state diagram shown in Fig. 1 for the filling curves shown. A total volume Vo can or is calculated in one embodiment based on an electrolyte density and a dosed electrolyte mass at which the filling curve begins to level off, the start of the leveling being denoted hereinafter by mo.Yes, in particular by the initial dosage of electrolyte, the empty cell volume is at least substantially filled. With each further or continued electrolyte dosage, in particular beyond the initial electrolyte dosage, cavities in the porous electrodes and, in embodiments, in a separator of the cell are wetted, which is schematically shown in Fig. 1 for embodiments with the fourth state diagram.

[0016] According to the Lucas-Washburn equation, the change in the wetted electrolyte mass can be determined to be proportional to the square root of time:

[0017] Δm / Δt = h(t) = K / √t

[0018] where t = 0 marks the start of a filling (time) section, referred to as an imbibition process in one embodiment, while here the electrolyte density p, the electrode porosity e, and the cross-sectional area A of the electrode are assumed to be constant. In other words, in one embodiment, t = 0 is set to the time at which mo is reached or becomes (the point at which the entire dead volume in the cell housing is filled with electrolyte). The inventors have found that thereafter a linear behavior of m(t) is ensured. The slope of this linear behavior represents the infiltration rate k [g / s 05 , which is used or can be used to quantify the filling rate. The above equation usually holds for a capillary-driven imbibition of a pure wetting process23 - 2686

[0019] a porous material. Although the measurement of electrolyte uptake in our environment does not fully meet these conditions (an external pressure is exerted), by plotting the change in electrolyte over the square root of time and specifying the start time t = 0 for the point at which mo is reached, a proportionality constant can be defined, which we denote as k:

[0020] m = k√t + mo

[0021] The rate k in [g / s A0.5] serves as the infiltration rate, which is used or can be used to characterize the infiltration behavior, in particular of various electrodes and separators. Accordingly, the term "infiltration rate", as used herein, should preferably be understood. Thereby, in one embodiment, a filling time can be influenced or determined, in particular by adjusting a filling pressure and / or an evacuation pressure. In one embodiment, the method has an optimization of the filling speed based on the infiltration rate, in particular can or is used for this purpose.

[0022] In one embodiment, during dry coating or by dry coating and / or during preparation or by preparation, a pore size distribution of the electrode is formed such that at least 70% of the pore sizes, or at least 80%, or at least 90% of the pore sizes, have a diameter of 0.6 to 2.2 µm. In one embodiment, the dry coating involves applying the material using rollers, wherein in one embodiment the material is directed by circumferential speed difference(s) of the rollers, particularly of counter-rotating rollers. In one embodiment, a roller for this purpose can have a diameter of at least 150 mm, or at least 190 mm and / or at most 250 mm, or at most 210 mm.In one embodiment, a first roller has a (rotational) speed that is, at least substantially, at least 0.4 times, or at least 0.3 times, and / or at most 0.6 times, or at most 0.7 times; or in particular 0.5 times; the (rotational) speed of a second roller, wherein a material is or can be applied between the rollers, in particular such that, in one embodiment, the material is aligned (in particular has a preferred direction), in particular by the difference in the (rotational) speeds, of a binder carried by the material, which is further in particular fibrillatable. In one embodiment, the first roller has a (rotational) speed of at least substantially 10 m / min. 23 - 2686.

[0023] Advantageously, in one embodiment, this enables the filling of the battery cell to be carried out more quickly. Advantageously, in one embodiment, this enables, in particular by introducing a preferred direction (in particular by means of the described rollers), a more homogeneous pore size distribution to be achieved or made possible.

[0024] In one embodiment, the dry coating has a porosity distribution with a porosity of at least 15% and / or at most 38% of the coating, or, in one embodiment, a porosity distribution with a porosity of at least 15% and / or at most 38% of the resulting coating is produced during the dry coating.

[0025] Advantageously, in one embodiment, it is possible to (further) reduce the filling time, in particular such that the production costs of the electrode or the battery can be (further) reduced.

[0026] In one embodiment, during dry coating and / or preparation, in particular by dry coating and / or preparation, a value for the effective tortuosity, in particular for filling the electrode, measured according to an electrochemical impedance spectroscopy measurement of E-1 * 1.6 is not exceeded, where E represents the porosity of the electrode.

[0027] Porosity in the sense of the invention means (empty volume in the electrode) / (total volume of the electrode). The porous structure of the electrodes slows down the mass transport in the electrolyte according to:

[0028]

[0029] Generally, the geometric tortuosity is defined as:

[0030]

[0031] This occurs due to detours in the transport path due to the geometry of porous structures. Here, d is the material thickness in the transport direction and deff is the effective path, i.e., the path length, through the material thickness. This relationship is described in more detail in: B. Tjaden, D. J. L. Brett, P. R. Shearing, International Materials Reviews 2018, 63, 47 - 67.

[0032] described in: B. Tjaden, D. J. L. Brett, P. R. Shearing, International Materials Reviews 2018, 63, 47 - 67.

[0033] The effective tortuosity in the sense of the invention can be described as follows.

[0034] Effective tortuosity. Includes ion flow inhibiting effects of the pore surface (i.e., roughness) and different cross - sectional areas of the pores ("constrictions"). Required for the experimental determination of T: porosity s, volume conductivity K b uik of the electrolyte, effective conductivity in the porous electrode K ef f.

[0035]

[0036] Where A is the surface area of the electrode probe and d is its thickness.

[0037] An electrochemical impedance spectroscopy measurement in the sense of the invention can be a known electrochemical impedance spectroscopy measurement method. In particular, the electrochemical impedance spectroscopy measurement method can be a measurement method as described in “Turtuosity Determination of Battery Electrodes and Separators by Impedance Spectroscopy” (Johannes Landesfeind et al. 2016, Journal of the Electrochemical Society 163 (7) A1373-A1387).

[0038] The (fast) charging ability of a battery cell is usually influenced by several factors, in particular by the materials used (electrochemically active materials, binders, conductive additives, electrolyte, separators), the composition of the electrodes, the cell format, thermal management, the charging profile, and the electrode microstructure parameters (layer thickness, porosity / compaction, areal density, tortuosity). Electrode microstructure parameters usually offer the greatest degree of freedom to influence the (fast) charging ability, especially for a given electrode composition. The parameters electrode thickness, porosity / compaction, and areal density usually cannot be changed independently of each other to improve the (fast) charging ability of a battery cell.In embodiments, the (fast) charging ability can be changed, in particular influenced, by reducing the layer thickness, increasing the porosity, reducing the surface loading and / or reducing the tortuosity. A tortuosity, in particular an effective one, is a (micro)structural parameter which is, at least essentially, independent of the other 23 - 2686 parameters (layer thickness, porosity, surface loading) and can be varied. A reduction in tortuosity can in particular be achieved by ensuring that the formed pore structure of the electrode has as little influence as possible on the mass transport in the electrolyte filling the pore space. An increased tortuosity usually represents a reduced effective conductivity of ions, in particular lithium, in the pore space and / or greater overpotentials, which in particular can have a negative impact on the performance and / or safety.

[0039] Parameter (layer thickness, porosity, surface loading) and can be varied. A reduction in tortuosity can in particular be achieved by ensuring that the formed pore structure of the electrode has as little influence as possible on the mass transport in the electrolyte filling the pore space. An increased tortuosity usually represents a reduced effective conductivity of ions, in particular lithium, in the pore space and / or greater overpotentials, which in particular can have a negative impact on the performance and / or safety.

[0040] Advantageously, in one embodiment, it can be achieved by means of the method described herein that a (micro) structure of the electrode is formed or can be formed for which in particular an improved fast charging performance can be achieved or is achieved, which in particular enables a (higher) current supply and thus in particular a reduction of the charging time(s), and furthermore in particular a reduction of the production time.

[0041] In one embodiment, the method described herein is used for manufacturing a battery cell, in particular a lithium-ion battery cell.

[0042] Advantageously, in one embodiment, it can be achieved by means of this that the battery cell can be produced faster and / or more cost-effectively.

[0043] In one embodiment, preparing the electrode involves evacuating the electrode. In one embodiment, the evacuation pressure is at least 10 mbar, or at least 1 mbar and / or at most 100 mbar, or at most 20 mbar. In one embodiment, a rough vacuum or a fine vacuum is produced or set during evacuation.

[0044] Advantageously, in one embodiment, this can enable the electrode to be filled more quickly.

[0045] It is within the scope of the invention for the method steps described above to be carried out in a different order and / or method steps to be combined and / or a method step to be integrated into another method step, particularly where it is technically sensible.

[0046] According to one embodiment of the present invention, a vehicle is provided, in particular a vehicle that, in particular at least, has a battery cell produced by or made by a method described herein. 23 - 2686

[0047] Advantageously, in one embodiment, this can enable the vehicle to be produced more cost - effectively or is produced more cost - effectively.

[0048] According to one embodiment of the present invention, a system for producing a battery cell, in particular for filling a battery cell, is provided. In one embodiment, the system is configured or designed to carry out a method described herein and / or comprises: means for dry - coating an electrode; means for preparing the electrode for filling with an electrolyte; and / or means for filling the electrode with a filling pressure of at least 4 bar.

[0049] In one embodiment, the system has at least one sensor, particularly for monitoring the filling pressure.

[0050] Advantageously, in one embodiment, this enables the filling pressure to be at least substantially constant over a predetermined period of filling the electrode, particularly (in one embodiment) to be regulated or can be regulated.

[0051] A means in the sense of the present invention can be formed in terms of hardware and / or software technology, in particular at least one, preferably a digital processing unit (CPU), graphics card (GPU) or the like, which is data- or signal-connected, in particular to a memory and / or bus system, and / or have one or more programs or program modules. The processing unit can be configured to process commands implemented as a program stored in a memory system, to capture input signals from a data bus and / or to output output signals to a data bus. A memory system can have one or more, in particular different, storage media, in particular optical, magnetic, solid-state and / or other non-volatile media. The program can be configured such that it embodies the methods described herein oris capable of being executed such that the processing unit can execute the steps of such methods and thus, in particular, can operate or monitor the system.

[0052] A computer program product may, in one implementation, have a storage medium, in particular computer-readable and / or non-volatile, for storing a program or instructions or with a program stored thereon or with instructions stored thereon, in particular its own. In one 23-2686

[0053] In one implementation, causing this program or these instructions to be executed by a system or a controller, in particular a computer or an arrangement of multiple computers, causes the system or the controller, in particular the computer or computers, to execute a method described herein or one or more of its steps, or the program or instructions are configured to do so.

[0054] The computer program can in particular be stored on a non-volatile data carrier. Preferably, this is a data carrier in the form of an optical data carrier or a flash memory module. This can be advantageous if the computer program as such is to be treated independently of a processor platform on which the one or more programs are to be executed. In another implementation, the computer program can be present as a file on a data processing unit, in particular on a server, and can be downloaded via a data connection, for example the Internet or a dedicated data connection, such as a proprietary or local network. In addition, the computer program can have a plurality of interacting individual program modules. The modules can in particular be configured or at least be usable in such a way that they are in the sense of distributed computing (engl."Distributed computing" is executed on various devices (computers or processing units) that are geographically separated and connected to each other via a data network.

[0055] The system may accordingly have a program memory in which the computer program is stored. Alternatively, the system may also be configured to access a computer program available externally, for example on one or more servers or other data processing units, in particular to exchange data with it that are used during the course of the method or computer program or represent outputs of the computer program.

[0056] The features and advantages explained with respect to the first aspect of the invention correspondingly also apply to the further aspects of the invention.

[0057] The terms "comprises", "includes", "contains", "has", "with", or any other variant thereof used herein are intended to cover a non - exclusive inclusion. For example, a method or a23 - 2686

[0058] device that comprises or has a list of elements is not necessarily limited to those elements, but may include other elements that are not expressly listed or that are inherent to such a method or such a device.

[0059] Furthermore, unless expressly stated to the contrary, "or" refers to an inclusive "or" and not an exclusive "or". For example, a condition A or B is satisfied by one of the following conditions: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

[0060] As used herein, the terms "a" or "an" are defined in the sense of "one or more". The terms "another" and "a further" and any other variant thereof are to be understood in the sense of "at least one other".

[0061] As used herein, the term "plurality", if used, is to be understood in the sense of "two or more".

[0062] For the purposes here, the terms "configured" or "arranged" to perform a certain function (and respective variations thereof), as used herein, are to be understood to mean that a relevant device or component thereof is already in a configuration or setting in which it can perform the function or is at least adjustable - i.e., configurable - such that it can perform the function after appropriate adjustment. The configuration can be effected, for example, by appropriate adjustment of parameters of a process or of switches or the like for activating or deactivating functionalities or settings. In particular, the device can have several predefined configurations or operating modes, such that the configuration can be effected by selecting one of these configurations or operating modes.

[0063] Further advantages, features and possible applications of the present invention result from the following detailed description in connection with the figures. In this regard, shows

[0064] Fig. 1 schematically shows the filling of a battery cell according to an embodiment of the present method; and 23-2686

[0065] Fig. 2 is a flow diagram illustrating an embodiment of the method according to the invention.

[0066] In the figures, like reference numerals designate like, similar or corresponding elements. The elements shown in the figures are not necessarily drawn to scale. Rather, the various elements shown in the figures are represented in such a way that their function and general purpose are understandable to the person skilled in the art. The connections and couplings between functional units and elements shown in the figures can, unless expressly stated otherwise, also be implemented as an indirect connection or coupling. Functional units can in particular be implemented as hardware, software or a combination of hardware and software.

[0067] Fig. 1 schematically shows the filling of a battery cell according to one embodiment of the present method. In the diagram, two curves are schematically shown that represent the filling process, where the upper curve represents the filled mass that is introduced into the battery cell and the lower curve represents the filling pressure that remains, at least substantially, constant over the filling period (x-axis) as long as dosing is carried out or (more) electrolyte is introduced into the battery cell. This is particularly shown by the schematic representations of a battery cell arranged above the diagram, where the first two representations represent a preparation for filling. In one embodiment, the preparation can be, in particular partial, evacuation orHave a pressure reduction in the battery cell, in particular to at most 50 mbar, or at most 30 mbar, or at most 11 mbar and / or at least 8 mbar, or at least 10 mbar. The third and fourth schematic representations of the battery cell (seen from the left) represent in particular a start of filling (see also the corresponding arrow to the corresponding point in time in the diagram), and a point in time during filling, wherein in the fourth representation the electrolyte entry into the shown pores is schematically outlined. The fifth schematic representation of the battery cell represents a state after completion of filling, which in particular (in one embodiment) has a pressure of 1 bar or normal pressure or ambient pressure. The method, as described herein and in particular shown in Fig. 1, is orIt can be carried out with a higher filling pressure, especially compared to wet-coated battery cells. 23 - 2686.

[0068] Fig. 2 shows a flow diagram for illustrating an embodiment of the method according to the invention, where S10 is the dry coating of an electrode for a battery cell, S20 is the preparation of the electrode for filling with an electrolyte, and S30 is the filling of the electrode with an electrolyte, where the filling has a filling pressure of at least 4 bar. The method can or is in particular repeated for further battery cells or is repeatable for further battery cells (represented by the arrow).

[0069] Although at least one exemplary embodiment has been described above, it should be noted that a large number of variations exist. It should also be noted that the described exemplary embodiments are only non-limiting examples, and it is not intended to limit the scope, applicability, or configuration of the devices and methods described herein. Rather, the foregoing description will provide those skilled in the art with guidance for implementing at least one exemplary embodiment, understanding that various changes can be made in the operation and arrangement of the elements described in an exemplary embodiment without departing from the subject matter defined in the appended claims and their legal equivalents.23-2686

[0070] LIST OF REFERENCE NUMBERS

[0071] S10 Drying the electrode for a battery cell

[0072] S20 Preparing the electrode for filling with an electrolyte

[0073] S30 Filling the electrode with an electrolyte, wherein the filling has a filling pressure of at least 4 bar.

Claims

23-2686 REQUIREMENTS 1. Method for filling a battery cell, in particular a lithium-ion battery cell, with electrolyte, comprising: Dry coating (S10) of an electrode for a battery cell; Preparing (S20) the electrode for filling with an electrolyte; filling (S30) the electrode with an electrolyte, wherein the filling has a filling pressure of at least 4 bar.

2. Method according to the preceding claim, characterized in that the filling pressure is at least 6 bar, or at least 10 bar, or at least 15 bar, or at least 20 bar and / or at most 30 bar, or at most 25 bar, in particular temporarily.

3. Method according to one of the preceding claims, characterized in that during dry coating (S10) and / or preparation (S20) a pore size distribution is formed such that at least 70% of the pore sizes have a diameter of 0.6 to 2.2 pm.

4. Method according to one of the preceding claims, characterized in that the dry coating (S10) has a porosity distribution with a porosity of at least 15% and / or at most 38% of the coating.

5. Method according to one of the preceding claims, characterized in that during dry coating (S10) and / or preparation (S20) a tortuosity, in particular for filling, of the electrode of at least 2.5 and / or at most 8.5 is formed and / or a value for an effective tortuosity measured according to an electrochemical impedance spectroscopy measurement of E-1 * 1.6 is not exceeded, wherein E represents the porosity of the electrode.

6. Method according to one of the preceding claims, characterized in that the preparation (S20) of the electrode comprises an evacuation of the electrode.

7. Use of a method according to any of the preceding claims for manufacturing a battery cell, in particular a lithium-ion battery cell. 23-2686 8. Vehicle comprising at least one battery cell manufactured by a method according to any one of claims 1 to 6.

9. System for filling a battery cell, characterized in that the system is configured and / or comprises a method according to one of claims 1 to 6: Means for dry coating (S10) an electrode; Means for preparing (S20) the electrode for filling with an electrolyte; Means for filling (S30) the electrode with a filling pressure of at least 4 bar.

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