Method for producing an electrochemical energy storage element
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-02-03
- Publication Date
- 2026-08-13
Smart Images
Figure EP2026052812_13082026_PF_FP_ABST
Abstract
Description
[0001] Method for manufacturing an electrochemical energy storage element
[0002] DESCRIPTION
[0003] The present invention relates to a method for manufacturing an electrochemical energy storage element. The invention further relates to an electrochemical energy storage cell that can be manufactured using such a method.
[0004] SCOPE OF APPLICATION AND STATE OF THE ART
[0005] Each electrochemical energy storage element as defined in the present application comprises at least one positive and at least one negative electrode, which are separated from each other by a separator. In electrochemical energy storage elements, an electrochemical, energy-releasing reaction takes place, which consists of two electrically coupled but spatially separated partial reactions. One partial reaction, occurring at a comparatively low redox potential, takes place at the negative electrode. The other partial reaction, occurring at a comparatively high redox potential, takes place at the positive electrode. During discharge, electrons are released at the negative electrode through an oxidation process. This results in an electron flow through an external load to the positive electrode, from which a corresponding quantity of electrons is absorbed. Thus, a reduction process takes place at the positive electrode.Simultaneously, for the purpose of charge equalization, an ion current corresponding to the electrode reaction occurs within the electrochemical energy storage element. This ion current traverses the separator and is enabled by an ion-conducting electrolyte.
[0006] In secondary (rechargeable) electrochemical energy storage cells, this discharge reaction is reversible. It is therefore possible to reverse the conversion of chemical energy into electrical energy that occurred during discharge. The common designation of the negative electrode as the anode and the positive electrode as the cathode in secondary energy storage cells refers to the discharge function of the electrochemical cell.
[0007] A commonly used electrochemical energy storage device is the lithium-ion cell. A lithium-ion cell comprises electrodes that can reversibly absorb and release lithium ions, as well as a lithium-ion-containing electrolyte. Lithium-ion cells can provide high currents and are characterized by a comparatively high energy density. The negative and positive electrodes of a lithium-ion cell are typically formed by so-called composite electrodes, which include both electrochemically active and electrochemically inactive components.
[0008] In principle, any material capable of absorbing and releasing lithium ions can serve as electrochemically active components (active materials) for secondary lithium-ion cells. For the negative electrode, carbon-based particles, such as graphitic carbon, are used. Active materials for the positive electrode can include lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium iron phosphate (LiFePO4), or derivatives thereof. These electrochemically active materials are typically present in particle form within the electrodes.
[0009] As electrochemically inactive components, composite electrodes generally comprise a planar and / or ribbon-shaped current collector, for example a metallic foil, which serves as a support for the respective active material. The current collector for the negative electrode (anode current collector) can be made of copper or nickel, for example, and the current collector for the positive electrode (cathode current collector) can be made of aluminum, for example.
[0010] Furthermore, the electrodes, as electrochemically inactive components, can include an electrode binder (e.g., polyvinylidene fluoride (PVDF) or another polymer, such as carboxymethylcellulose), conductivity-enhancing additives, and other admixtures. The electrode binder ensures the mechanical stability of the electrodes and often also the adhesion of the active material to the current collectors.
[0011] Lithium-ion cells typically use electrolytes consisting of solutions of lithium salts such as lithium hexafluorophosphate (LiPF6) in organic solvents (e.g., ethers and esters of carbonic acid).
[0012] In general, during the manufacture of a lithium-ion cell, the composite electrodes are combined with one or more separators to form an electrode-separator assembly. The electrodes and separators are often, but not necessarily, bonded together under pressure, possibly also by lamination or adhesive bonding. The basic functionality of the cell can then be achieved by impregnating the assembly with the electrolyte.
[0013] Various designs are known for electrochemical energy storage elements, and especially for lithium-ion cells. Besides prismatic shapes, button cells and cylindrical cells are widely used. Both button cells and cylindrical cells have a round, and in particular a circular, base. Cylindrical cells differ from button cells in that button cells have a height that is less than their diameter, while cylindrical cells have a height that is greater than their diameter.
[0014] The housings of electrochemical energy storage elements are often composed of a cup-shaped element (or simply "cup") and a lid-like element (or simply "lid"). The electrochemical components of the energy storage element are arranged inside the housing and electrically connected to the housing and / or the terminals of the energy storage element.
[0015] Particularly in cylindrical energy storage elements, the electrode-separator assembly can be formed or processed into a coil. For manufacturing, for example, a ribbon-shaped positive electrode and a ribbon-shaped negative electrode, along with at least one ribbon-shaped separator, are fed separately to a winding machine and wound helically in the sequence positive electrode / separator / negative electrode. In other cases, a ribbon-shaped positive electrode and a ribbon-shaped negative electrode, along with at least one ribbon-shaped separator, are first combined into an electrode-separator assembly, for example, by applying the aforementioned pressure. In a further step, the assembly is then wound.
[0016] For applications in the automotive sector, for e-bikes or for other applications with high energy demands, such as in power tools, lithium-ion cells with the highest possible energy density are required, which are also capable of withstanding high currents during charging and discharging.
[0017] Energy storage cells with an electrode-separator assembly in the form of a winding for the aforementioned applications are typically designed as cylindrical cells, often with a length or height between 50 mm and 150 mm and a diameter ranging from 15 mm to 60 mm. Modern lithium-ion cells with, for example, a form factor of 21 x 70 (diameter x height in mm) can achieve an energy density of up to 270 Wh / kg.
[0018] Traditionally, the electrodes of an energy storage element are electrically contacted with the electrical poles of the respective housing via strip-shaped metal plates (tabs), which are welded to the electrodes at one end and connected to components of the housing at the other. In recent years, lithium-ion cells have increasingly been developed in which the electrodes are contacted using a so-called "tab / ess design." This design partially or completely dispenses with the aforementioned tabs. Instead, coiled electrode-separator assemblies are manufactured in which the electrodes have metallic current collectors (current collector foils) with uncoated longitudinal edges (free edge strips) that protrude from the coil at the end faces. Metallic contact plate components can be welded onto these longitudinal edges, as described, for example, in WO 2017 / 215900 A1.This makes it possible to electrically contact the current collector, and thus the associated electrode, along its entire length. This significantly reduces the internal resistance within the cells. Consequently, the occurrence of high currents can be absorbed much more effectively, and heat can also be dissipated more efficiently from the electrode winding.
[0019] For the production of the wound assembly with the coiled electrode-separator assembly and the attached contact plate components, the contact plate components are typically pressed and welded to the end faces of the coil from the respective side of the coiled electrode-separator assembly, often using a laser. For this process, the coiled electrode-separator assembly is usually positioned on its side on a prismatic mount, allowing the contact plate components to be attached to the end faces. In other manufacturing processes, the coiled electrode-separator assembly is aligned by means of a cylindrical guide during the attachment of the contact plate components.
[0020] The problem here is that pressing the contact sheet components onto both ends of the winding can result in asymmetrical compression on both ends, since deformation generally occurs in the end-face areas primarily where there is the least resistance. In particular, differing material and geometric properties in the end-face areas of the winding cause the pressure applied to the ends to deform the free edge strips of the current collector foils unevenly.The reasons for the differing material and geometric properties in the end-face areas of the winding lie primarily in the varying film thickness and material properties of the protruding uncoated edge areas of the current collector films, as well as in their respective geometries, particularly regarding the width of these protruding uncoated edge strips on both end faces of the electrode winding. Furthermore, variations due to the manufacturing process of the electrode winding and variations due to different material batches also play a role.For example, if the aluminum current collector foil in the cathode-side end region of the electrode winding is thinner than the copper current collector foil in the anode-side end region of the electrode winding, the deformation takes place primarily at the cathode-side end region, so that the deformation on the cathode side can already reach critical areas before a significant deformation takes place at the anode-side end region.
[0021] Since it is impossible to control the degree to which each end of the winding is compressed, the overall compression depth is typically kept correspondingly low. Otherwise, one-sided over-compression could damage the separator, leading to an internal short circuit. However, this safety-related limitation of the total compression depth has the disadvantage that the internal volume of the cell, and therefore its potential capacity, cannot be fully utilized.
[0022] TASK AND SOLUTION
[0023] The present invention therefore aims to provide an improved manufacturing process for electrochemical energy storage elements with coiled electrode-separator assemblies in a Tabless design, which avoids the described disadvantages.
[0024] To solve this problem, the present invention proposes the method described below for manufacturing an electrochemical energy storage element comprising an electrode-separator assembly and a housing. Energy storage elements that can be manufactured according to this method are also encompassed by the invention.
[0025] The method according to the invention comprises the following process steps:
[0026] a) An electrode-separator assembly in the form of a cylindrical winding with a first terminal end face and a second terminal end face and an intermediate winding jacket is provided, wherein
[0027] i. the electrode-separator assembly consists of ribbon-shaped electrodes and at least one ribbon-shaped separator,
[0028] ii. the ribbon-shaped electrodes and the ribbon-shaped separator are wound around a winding axis that defines the axial center of the winding,
[0029] iii. the ribbon-shaped electrodes comprise at least one anode and at least one cathode, wherein
[0030] the anode comprises an anode current collector having a strip-shaped main area loaded with a layer of negative electrode material, and a free edge strip extending along a longitudinal edge of the anode current collector that is not loaded with the negative electrode material, and / or
[0031] the cathode comprises a cathode current collector having a strip-shaped main region loaded with a layer of positive electrode material, and a free edge strip extending along a longitudinal edge of the cathode current collector which is not loaded with the positive electrode material, and wherein
[0032] the anode and / or the cathode within the electrode-separator assembly are arranged such that the free edge strip of the anode current collector protrudes from the first terminal end face, forming a protrusion, and / or the free edge strip of the cathode current collector protrudes from the second terminal end face, forming a protrusion.
[0033] b) A contact plate part is placed on at least one of the end faces of the electrode-separator assembly,
[0034] c) The at least one attached contact plate part is pressed onto the end face by deformation of the respective protrusion of the anode current collector or the cathode current collector and welded to the electrode-separator assembly,
[0035] d) the electrode-separator assembly with the at least one contact plate part is inserted into a housing,
[0036] e) The electrode-separator assembly with the at least one contact plate part is electrically contacted with the housing.
[0037] The process is further characterized by the fact that
[0038] f) the electrode-separator assembly with the at least one attached contact plate part is axially fixed during pressing and welding in step c), and that
[0039] g) axial fixation is achieved by radial clamping on the circumference of the winding jacket.
[0040] In this process, the coiled electrode-separator assembly (hereinafter also referred to as the electrode coil) is axially fixed during the end-face pressing of the contact plate(s). This creates a fixed counterpart for the pressing process of the contact plate(s) against the end face(s) of the electrode coil, so that the forces acting on the end faces essentially no longer influence each other and the pressing process can be controlled in a particularly advantageous manner. The pressing of the contact plate(s) against the end faces of the electrode coil can thus be carried out in a controlled manner, preventing undesirable uneven and asymmetrical deformation of the current collector protrusions. In particular, this reliably prevents excessive compression on one or both end faces of the electrode coil.Excessive compression would damage the separator and thus lead to the formation of internal short circuits.
[0041] Furthermore, this improved process allows for a higher degree of compression when contacting the anode and / or cathode ends of the electrode winding in the end face area. This enables the use of a wider coating width for the electrode strips within the same space requirement, thereby increasing cell capacity through optimized utilization of the cell's internal volume. The high degree of compression achievable with this method thus allows for optimized volume utilization within the cell, resulting in increased capacity.
[0042] The axial fixation during the pressing of the contact plate(s) allows for targeted and controllable axial compression of the respective current collector protrusion, enabling precise and free adjustment of the overall compression degree and / or separately for each of the two ends of the electrode winding. The compression degree describes the degree of compression of the protrusion(s) formed by the free edge strips of the current collector(s). This eliminates the need for a safety margin to maintain the total pressing depth.
[0043] The very high compression ratios achievable according to the invention also make it possible for the electrode winding to transmit significantly higher axial forces compared to conventional cells, which can be very advantageous for some applications of electrochemical energy storage elements. In particular, this also offers advantages when inserting the electrode winding into a housing and during further assembly. For example, when closing the housing by crimping, large forces can act on the end faces of electrode windings because a seal is pressed against the end face. Axially compressed electrode windings can counteract these forces much more effectively.
[0044] A further significant advantage arises with regard to the sealing function during the assembly of the energy storage elements. The sealing function is supported by the high force absorption of the electrode winding, as the seal can be pressed against the electrode winding. Welding according to the aforementioned step c) creates a material-bonded connection between the free edge strip of the respective current collector and the respective contact plate section. This welding process is also facilitated by the axial fixation of the electrode winding. In particular, the targeted axial compression of the end-face protrusions of the current collectors (current collector foils) reliably shields the separator, thus preventing internal short circuits.Furthermore, the targeted axial compression creates a larger heat sink on the back side of the respective contact plate section, enabling a particularly efficient welding process. Additionally, the tightly compressed overhang of the current collector foil at the end face of the winding results in a particularly good ratio between the joining partners, namely the thin contact plate section and the tightly compressed winding end. Finally, the controlled and maximized compression at the winding ends reduces voids in this area, further facilitating the welding process and simultaneously optimizing the volume utilization within the cell.
[0045] In particularly advantageous embodiments of the method according to the invention, the following additional feature is provided:
[0046] a) Radial clamping is carried out using a jaw chuck, in particular using a multi-segment jaw chuck.
[0047] Especially with a multi-segment chuck, axial fixation of the electrode winding is possible in a particularly reliable manner. A chuck allows the electrode winding to be gripped evenly and axially fixed around its entire circumference.
[0048] In preferred embodiments of the method, the clamping element for radial clamping, for example the chuck, engages in the central region of the longitudinal extent of the electrode winding. Preferably, the clamping element covers 70–90% of the longitudinal extent of the electrode winding. In particularly preferred embodiments of the method, the clamping zone of the clamping element extends to 80–85% of the longitudinal extent of the electrode winding.
[0049] Preferably, the pressing of the at least one contact plate part onto the respective end face of the electrode winding and the welding of the contact plate part are carried out in one operation.
[0050] In particularly preferred embodiments of the method according to the invention, the following additional feature is provided: a) The welding of the at least one contact plate part to the electrode-separator composite is carried out by laser treatment.
[0051] Laser welding is particularly preferred because it allows for very precise and accurate welding with low heat input. Furthermore, laser welding can be performed at high speeds and is easily automated.
[0052] In the method according to the invention, it can be provided that a contact plate is provided on only one side of the winding for contacting the electrodes, so that only one of the electrodes is contacted via a contact plate. The other electrode is contacted in another way, for example by means of a tab as described above. In these embodiments, the pressure for pressing the contact plate against the respective end face of the winding is expediently applied only on one side. The method according to the invention is particularly suitable for such embodiments, since the axial fixation of the electrode winding allows for particularly good control of an asymmetrically applied axial pressure.
[0053] In particularly preferred embodiments of the method according to the invention, the following additional feature is provided:
[0054] a) A contact plate part is placed on each of the end faces of the electrode-separator assembly and pressed and welded to the respective end face.
[0055] In these embodiments, both the anode and the cathode are electrically contacted at their respective end faces of the electrode winding via contact plate components. These contact plate components can, in particular, be disc-shaped contact plates known per se.
[0056] In preferred embodiments, the contact sheet parts are characterized by at least one of the following features a) to c):
[0057] a) Metal plates with a thickness in the range of 50 pm to 600 pm, preferably 150 - 350 pm, are used as contact plate parts.
[0058] b) The contact plate parts are made of alloyed or unalloyed aluminum, titanium, nickel or copper, but optionally also of stainless steel (for example, type 1.4303 or 1.4304) or nickel-plated steel. c) The contact plate parts are dimensioned such that they cover at least 25%, preferably at least 50%, particularly preferably at least 75% of the end face on which they are mounted.
[0059] In cases where the housing is cylindrical, contact plate components are generally used that have the shape of a disc, in particular a circular or at least approximately circular disc. They therefore have an outer circular or at least approximately circular disc edge.
[0060] In particularly preferred embodiments, the anode current collector and the contact sheet welded to it, in particular the contact plate welded to it, are both made of the same material.
[0061] Preferably, axial pressure is exerted on both end faces of the electrode-separator assembly to press the respective contact plate part against the two end faces.
[0062] In preferred embodiments, it is provided that the applied axial pressure, in particular the axial pressure applied on both sides, is controllable and / or adjustable.
[0063] It can be designed so that the pressure applied to both sides is the same (symmetrical pressing).
[0064] In other embodiments, the following additional feature is provided:
[0065] a) The axial pressure exerted on both end faces is different.
[0066] In this preferred embodiment of the method with an asymmetrically applied pressure, it is particularly advantageous that the differing pressure applied to both ends of the electrode winding results in a uniform deformation of the respective protrusions of the current collectors on both end faces of the electrode winding, even if the material properties and geometries in the area of the end faces of the electrode winding differ. For example, if...Since the film thickness of the current collector strips and / or the softness of the material and / or the width of the free edge strips of the current collectors differ, maximum compression at the end faces of the electrode winding can be achieved by controlling the pressure applied on both sides and by the counter-pressure by means of the axial fixation of the electrode winding according to the invention, without the risk of over-compression at one of the end faces and thus the risk of an internal short circuit. In further preferred embodiments of the method according to the invention, the following additional feature can be provided:
[0067] a) The free edge strips of the cathode current collector and / or the anode current collector are bent radially inwards at least section by section before the at least one contact plate part is placed on it.
[0068] b) The electrode-separator assembly is inserted into a housing cup with the at least one contact plate part, which is closed with a lid, the contact plate part serving as the lid and an edge section of the housing cup being bent radially inwards over the contact plate part.
[0069] The advantages of the embodiment of the method according to the invention according to feature a) are particularly relevant in cases where the diameter of the end faces of the electrode winding is larger than the diameter of the contact sheet parts.
[0070] This embodiment addresses the problem that, for assembly and safety reasons, the contact plate components, for example, disc-shaped contact plate components, should not protrude beyond the edges of the electrode winding's end faces. Otherwise, the risk of unintended contact between the contact plate components and the cell housing is too great. Furthermore, there are sometimes high tolerances for individual components and limited positioning accuracy when welding the contact plate components. For these reasons, it can be advantageous for the contact plate components to have a smaller diameter than the winding diameter. Additionally, the weld seam positioning during welding is also subject to certain manufacturing tolerances, meaning the weld cannot be executed right up to the outer edge of the contact plate components.This results in the outer turns of the electrode winding not being able to be bonded to the contact sheet parts in a material-bonded manner and possibly not being in direct contact with the contact sheet parts, which leads to an increased internal resistance.
[0071] The aforementioned bending of the free edge strips of the current collectors ensures that, particularly when using contact plate components whose diameter is smaller than the winding diameter, the outer winding can still be bonded to the contact plate component. The radial bending of the edge strip reduces the diameter of the outer winding, at least in sections, so that the longitudinal edge of the edge strip in the outer winding can also be covered by the contact plate component.
[0072] Particularly preferred is the area of the edge strip encompassed by the outer winding, which is bent radially inwards over its entire length.
[0073] In the preferred embodiment according to feature b), the electrode-separator assembly, together with at least one contact plate component applied to one of the end faces, is inserted into a housing cup, which is then closed by a lid. The contact plate component can serve as the lid and close the opening of the housing cup. To close the housing, an edge section of the housing cup is bent radially inwards so that the bent edge section overlaps the edge of the contact plate component. Forming the edge section creates a positive-locking connection between the housing cup and the contact plate component. The axial forces introduced during the bending are transmitted to the electrode-separator assembly via the contact plate component.
[0074] The invention utilizes the axial load-bearing capacity of the compressed overhangs of the electrode-separator assembly, ensuring that the clamping forces occurring during forming are reliably absorbed and transferred into the winding. The radially inwardly bent edge section of the housing cup, in combination with the contact plate section and the axial support provided by the electrode-separator assembly, forms a mechanically stable lid structure that simultaneously maintains a sealing function between the housing cup and the contact plate section. More on this below.
[0075] The invention further comprises electrochemical energy storage elements that can be manufactured according to the described method. In particular, these energy storage elements are characterized by the fact that at least one of the protrusions formed by the free edge strips of the current collectors is deformed, and preferably exhibits a controlled degree of compression. Preferably, both protrusions are deformed and exhibit a controlled degree of compression. The degree of compression here describes the ratio of the initial height of the protrusion in the axial direction before the contact plate part is pressed on to the height of the protrusion after deformation, i.e., after pressing and welding on the contact plate part.
[0076] Such energy storage elements are preferably inserted into a housing with the contact plate component, which is closed by a cover. The closure can be achieved, for example, by crimping. The housing can have a tool engagement structure such as a rolled bead for this purpose.
[0077] A particularly preferred electrochemical energy storage element produced or producible by the described process is characterized by the following features:
[0078] a) It comprises an electrode-separator assembly in the form of a cylindrical winding with a first terminal end face and a second terminal end face and an intermediate winding sheath, wherein
[0079] i. the electrode-separator assembly consists of ribbon-shaped electrodes and at least one ribbon-shaped separator,
[0080] ii. the ribbon-shaped electrodes and the ribbon-shaped separator are wound around a winding axis that defines the axial center of the winding,
[0081] iii. the ribbon-shaped electrodes comprise at least one anode and at least one cathode, wherein
[0082] the anode comprises an anode current collector having a strip-shaped main area loaded with a layer of negative electrode material, and a free edge strip extending along a longitudinal edge of the anode current collector that is not loaded with the negative electrode material, and / or
[0083] the cathode comprises a cathode current collector having a strip-shaped main region loaded with a layer of positive electrode material, and a free edge strip extending along a longitudinal edge of the cathode current collector which is not loaded with the positive electrode material, and wherein
[0084] the anode and / or the cathode within the electrode-separator assembly are arranged such that the free edge strip of the anode current collector protrudes from the first terminal end face, forming a protrusion, and / or the free edge strip of the cathode current collector protrudes from the second terminal end face, forming a protrusion;
[0085] b) a contact plate part is attached to at least one of the end faces of the electrode-separator assembly;
[0086] c) the free edge strip forming the overhang on the respective end face with an attached contact plate part is deformed by the attached contact plate part, and the overhang formed by the free edge strip is compressed in the axial direction by 10-75% compared to its uncompressed extent and thus forms an axially load-bearing compression body; d) the at least one attached contact plate part is welded to the end face with the electrode-separator assembly; and
[0087] e) The electrode-separator assembly with the at least one contact plate part is inserted into a housing.
[0088] In particularly preferred embodiments, the energy storage element is characterized by the following feature:
[0089] f) The attached contact plate part forms a wall of the housing.
[0090] In this preferred embodiment, the electrode-separator assembly with the attached contact plate component is thus inserted into a housing that surrounds the winding, with the contact plate component forming a wall of the housing, in particular a lid or a bottom of the housing. By designing the contact plate component as a wall component, the housing closure can be made particularly compact, since no separate lid assembly with additional pole structures is required. The axial load-bearing capacity of the compression body formed by the compression enables the contact plate component to be mechanically supported when the housing is closed and to absorb the forces occurring during the closing process.
[0091] In particularly preferred embodiments, electrochemical energy storage elements according to the invention are characterized by at least one of the following additional features:
[0092] a) The deformed supernatants of the anode current collector and / or the cathode current collector have a degree of compression of 20 to 60%, preferably 30 to 50%, particularly preferably 40 ± 5%.
[0093] b) The contact plate part is pressed against the electrode-separator assembly by an axial closing pressure generated when the housing is closed.
[0094] The percentages mentioned can refer to the respective protrusions of the anode current collector and / or the cathode current collector, or to the sum of these protrusions. Preferably, they refer to the protrusion formed by the free edge strip in the axial direction relative to its uncompressed extent.
[0095] In one embodiment of a lithium-ion cell with the form factor 18650, for example, the sum of the cathode-side and anode-side protrusions of the current collectors on the end faces of the electrode winding before crimping can be between 4 and 5 mm. After crimping and welding of the contact plate parts, the sum of the protrusions can be between 2 and 3 mm.
[0096] When the housing is closed, an axial closing pressure is exerted on the cell's lid structure. This closing pressure is generated, for example, by forming or crimping an edge section of the housing cup that is guided over the contact plate component. The closing pressure is transferred to the contact plate component, which is thereby pressed axially against the electrode-separator assembly.
[0097] The electrode-separator assembly mechanically absorbs this axial closing pressure and acts as a counter-element against the housing cup. This is made possible by the previously formed axially load-bearing compression body, which arises from the compressed protrusions of the free edge strips. The compression body provides a stable axial load path between the contact plate part and the winding interior, so that the forces occurring during closing can be reliably transferred into and absorbed by the electrode-separator assembly.
[0098] This axial support allows the contact plate component to act as a cover component of the housing, eliminating the need for additional structural reinforcements or rolled edges. The force transmission between the housing cup, contact plate component, and electrode-separator assembly ensures a mechanically stable and permanently leak-proof housing closure.
[0099] In further embodiments of the electrochemical energy storage elements, the following additional feature is provided:
[0100] a) The deformed protrusions of the anode current collector and the cathode current collector exhibit an identical degree of compression.
[0101] The inventive method enables precise adjustment of the degree of compression at both ends of the electrode winding by axially fixing the electrode winding during the pressing and welding of the contact plate parts. If the material properties and the geometries of the protrusions formed by the free edge strips of the current collectors differ at the ends of the electrode winding, it is particularly advantageous to apply different axial pressures to the two ends for pressing, in order to achieve an identical degree of compression at both ends.
[0102] Due to the high compression ratios achievable according to the invention, the electrode winding of the electrochemical energy storage elements manufactured according to the invention is able to transmit higher axial forces compared to conventional energy storage elements. This can be used in the manufacture of the energy storage elements to eliminate the need for, for example, a rolled bead or other tool engagement structures that are conventionally used for crimping when closing the housing, as already mentioned. In particularly preferred embodiments of the electrochemical energy storage elements manufactured according to the invention, the energy storage elements are therefore characterized by the fact that they do not have rolled bead or other tool engagement structures on the housing that are conventionally used to engage a tool when closing an opening of the housing cup.Due to the deformed and compressed free edge strip(s) of the current collectors, the electrode winding with the attached contact sheet parts is sufficiently stable as such to counteract the axial forces acting during closing, so that corresponding sections of the housing can be bent over to close the housing without the risk of damaging the electrode winding.
[0103] The electrochemical energy storage element according to the invention is further characterized in preferred embodiments by at least one of the following additional features a) to f):
[0104] a) The electrochemical energy storage element has a cylindrical housing, wherein the attached contact plate part forms an end wall of the housing.
[0105] b) The electrochemical energy storage element has a cylindrical housing comprising a housing cup and a lid, wherein the contact plate part is designed as the lid that closes the opening of the housing cup.
[0106] c) An edge section of the housing cup is bent over the contact plate part.
[0107] d) The electrochemical energy storage element includes a seal that electrically isolates the contact plate part and the housing cup from each other.
[0108] e) The seal is axially compressed between the bent edge section of the housing cup and the contact plate part.
[0109] f) The electrochemical energy storage element (100) is a cylindrical cell.
[0110] The aforementioned features a) to c) and f) are preferably implemented in combination. Furthermore, features c) to e) are preferably implemented in combination. Particularly preferably, all features a) to f) are implemented in combination. The electrochemical energy storage element thus preferably has a cylindrical housing that accommodates the electrode-separator assembly and provides external mechanical and electrical protection, wherein an end wall of the housing is formed by an attached contact plate that rests on an end face of the electrode-separator assembly and establishes an electrical connection to the respective electrode. The contact plate thus performs both an electrical contacting function and a mechanical function as a cover component.
[0111] A seal can be arranged between the housing cup and the contact plate, electrically isolating the two components from each other. In the assembled state, the seal is preferably located between the bent edge of the housing cup and the contact plate and is compressed axially. This axial compression ensures a reliable seal of the housing and prevents direct metallic contact between the housing cup and the contact plate.
[0112] The axial forces generated during closing are transferred via the contact plate component to the electrode-separator assembly, which acts as a counter-element and mechanically supports the axial compression of the seal. This is made possible by the previously formed axially compressed protrusions of the free edge strips, which form an axially load-bearing compression body. The contact plate component can thus function as an axial load carrier, transferring the closing pressure generated during the forming of the housing cup via the compression body into the winding.
[0113] The sealing force transmission function is ensured entirely by the interaction of the contact plate component, the axially compressed seal, and the load-bearing compression body, thus eliminating the need for additional forming structures in the housing. This enables particularly compact and material-efficient housing geometries.
[0114] The electrochemical energy storage element is preferably a cylindrical cell with a form factor of 18650 or 21700. However, the invention is not limited to cylindrical cells with a form factor of 18650 or 21700. In particular, the method according to the invention is also applicable to larger cell formats with particular advantage.
[0115] In particularly preferred embodiments, the energy storage element producible according to the invention is a lithium-ion cell. The electrochemical energy storage element according to the invention is further characterized in preferred embodiments by at least one of the following additional features a) and b):
[0116] a) The contact plate part is stiffened by beads which are embossed axially or radially into the contact plate cover.
[0117] b) The contact plate part is welded to the deformed free edge strip.
[0118] The ribs increase the bending stiffness of the contact plate component, enabling it to reliably withstand both the axial closing pressure generated when the housing is closed and operational mechanical loads. Furthermore, the stiffening structures allow the contact plate component to be manufactured with a particularly thin material thickness without compromising the mechanical integrity of the cover area.
[0119] The contact plate component is preferably metallurgically bonded to the free edge strip of the electrode-separator assembly protruding from the respective end face. To achieve the welding of the contact plate component to the end face of the electrode-separator assembly, the contact plate component is pressed onto the protrusion and welded to the free edge strip forming the protrusion. The deformed and compressed protrusion created by the pressing process provides a large-area and stable contact zone. The weld forms a permanently mechanically robust and electrically conductive connection between the current collector and the contact plate component. The combination of defined axial compression of the protrusion and the metallurgical bond results in homogeneous contact of the end face, which is mechanically stabilized and simultaneously exhibits low contact resistance.
[0120] In a further preferred embodiment, the electrochemical energy storage element according to the invention is characterized by the following additional feature a):
[0121] a) The contact plate part has a filling hole which is closed by a metal part which is welded onto the contact plate part.
[0122] After electrolyte filling, an open formation preferably occurs, followed by sealing the filling hole with the metal part. This is preferably welded onto the contact plate part. The metal part forms a hermetic seal and ensures that the housing is completely sealed after filling. The welded seal creates a secure, mechanically robust, and permanently leak-proof seal that provides reliable containment of the electrolyte, independent of the preceding open formation. The electrochemical energy storage element according to the invention is further characterized in preferred embodiments by at least one of the following additional features a) and b):
[0123] a) The housing includes a base with PRV functionality.
[0124] b) The contact plate part includes PRV functionality.
[0125] The housing of the electrochemical energy storage element can incorporate a pressure relief function that allows for defined pressure relief in the event of impermissible internal overpressure. For this purpose, the base of the housing, particularly the base of the aforementioned housing cup, can be equipped with a pressure relief structure designed as a PRV (Pressure Relief Vent). The PRV structure of the base can be designed to open in a controlled manner when a predetermined internal pressure is reached, thereby ensuring safe pressure equalization without causing uncontrolled housing damage. Integrating the PRV functionality into the base enables a compact design of the cover or contact plate region and spatial separation between electrical contact structures and safety elements.
[0126] Alternatively or additionally, the contact plate component, which serves as the housing's lid, can incorporate pressure relief valve (PRV) functionality. The contact plate can be structured to include a locally weakened area, a predetermined breaking point, or a defined deformation zone that yields in a controlled manner in the event of internal overpressure. The pressure relief function within the contact plate can be independent of or integrated into the electrical contact function. By integrating the PRV functionality into the contact plate, a particularly compact housing design can be achieved, as the contact plate already seals the front opening of the housing cup, providing sufficient space in this area for a pressure-sensitive structure.
[0127] Regarding further features of the energy storage elements according to the invention, reference is also made to the above description in connection with the manufacturing process.
[0128] Further advantages and features of the invention will become apparent from the following description of exemplary embodiments, which are explained in more detail with reference to the drawings. The individual features can be implemented individually or in combination with one another. BRIEF DESCRIPTION OF THE DRAWINGS
[0129] The drawings show:
[0130] Figure 1 Illustration of the structure of the coiled electrode-separator assembly;
[0131] Figure 2 schematic cross-sectional view of an electrochemical energy storage element;
[0132] Figure 3 schematic representation to illustrate the attachment of contact sheet parts to a coiled electrode-separator assembly according to a conventional method (state of the art);
[0133] Figure 4 schematic representation to illustrate the attachment of contact sheet parts to a coil-shaped electrode-separator assembly according to the inventive method;
[0134] Figure 5 Illustration of the measurement of a coil-shaped electrode-separator assembly with attached contact sheet parts before and after pressing according to the inventive method;
[0135] Figure 6 photographic representation of the cathode-side end face region of a coil-shaped electrode separator assembly with welded-on contact plate part according to a conventional manufacturing method;
[0136] Figure ? Photographic representations of the cathode-side end face area (top) and the anode-side end face area (bottom) of a coiled electrode separator assembly with welded contact sheet parts under excessive overall compression according to a conventional manufacturing method;
[0137] Figure 8 photographic representations of the cathode-side end face region (top) and the anode-side end face region (bottom) of a coil-shaped electrode separator assembly with welded-on contact sheet parts in the invention:
[0138] Figure 9 schematic representation of a preferred embodiment of an electrochemical energy storage element; and
[0139] Figure 10: Sectional view of the energy storage element shown in Fig. 9. DESCRIPTION OF PREFERRED EXECUTION EXAMPLES
[0140] The inventive method for manufacturing an electrochemical energy storage element is characterized in that the coiled electrode-separator assembly (electrode coil) is axially fixed by radial clamping during the application of contact plate components to one or both end face regions of the electrode coil. This measure creates a counter-force during the pressing and welding of the contact plate component(s), which allows for a controlled pressure build-up and thus enables the protrusion(s) formed by the free edge strips of the current collectors to be deformed and compressed in a controlled manner. In particular, this method ensures that both coil ends are pressed in to the same depth.
[0141] The electrochemical energy storage elements that can be produced using the method according to the invention comprise a coiled electrode-separator assembly designed for the attachment of one or two contact plate parts to one or both end faces of the coiled electrode-separator assembly. Fig. 1 illustrates the structure of such an electrode-separator assembly 104. The assembly 104 includes the ribbon-shaped anode 105 with the ribbon-shaped anode current collector 106, which has a first longitudinal edge 106a and a second longitudinal edge parallel thereto. The anode current collector 106 is a foil made of, for example, copper or nickel. This comprises a ribbon-shaped main area coated with a layer of negative electrode material 107, as well as a free edge strip 106b that extends along its first longitudinal edge 106a and is not coated with the electrode material 107.Furthermore, the assembly 104 comprises the ribbon-shaped cathode 108 with the ribbon-shaped cathode current collector 109, which has a first longitudinal edge 109a and a second longitudinal edge parallel to it. The cathode current collector 109 is, in particular, an aluminum foil. It comprises a ribbon-shaped main area coated with a layer of positive electrode material 110, as well as a free edge strip 109b extending along its first longitudinal edge 109a and which is not coated with the electrode material 110. Both electrodes are shown individually in their unwound state in the upper part of Fig. 1.
[0142] The anode 105 and the cathode 108 are arranged offset from each other within the electrode-separator assembly 104 (see lower left in Fig. 1), so that the free edge strip 106b of the anode current collector 106 emerges from the first terminal end face 104a and the free edge strip 109b of the cathode current collector 109 emerges from the second terminal end face 104b of the wound electrode-separator assembly 104 (see lower right in Fig. 1).
[0143] 1) The ribbon-shaped anode 105 and the ribbon-shaped cathode 108 are separated from each other in the wound state by ribbon-shaped separators 156 and 157 (see bottom left in Fig. 1).
[0144] The diagram at the bottom right shows the electrode-separator assembly 104 in wound form, as it can be used in an energy storage cell according to the invention. The winding sheath 104c can be formed from a plastic film.
[0145] The free edge strips 106b and 109b of the current collectors, protruding from the end faces 104a and 104b of the electrode winding, are free of electrode material and are available for electrical contact of the electrodes with a contact plate part or another component of the energy storage element. The free edge strips 106b and 109b form the projections that are deformed during the pressing and welding of the contact plate part(s).
[0146] The energy storage element 100, schematically depicted in Fig. 2, comprises an electrode-separator assembly 104, which is in the form of a cylindrical electrode winding with two end faces 104a and 104b and an intermediate winding sheath, as shown in Fig. 1. In this embodiment, the free edge strip 106b of the anode current collector 106 protrudes from the (upper) first end face 104a. The edge strip 106b is not loaded with electrode material. The edge strip 106b is welded to the (upper) contact plate part 112, which rests on the edge strip 106b and covers most of the first end face 104a. During assembly, the contact plate part 112 is pressed against the first terminal end face 104a, so that the protrusion formed by the edge strip 106b is deformed in a manner not shown here.
[0147] Furthermore, the energy storage element 100 comprises an airtight and liquid-tight housing, which includes a metallic housing cup 101 with a (top) end circular opening and a cover 102 that closes the circular opening. The cover 102 includes a metal disc 113, the underside of which defines the interior of the housing, and a terminal cap 117, which sits directly on the metal disc 113 and is in electrical contact with it. An electrical conductor 133 connects the contact plate part 112 and the cover 102.
[0148] In the lower region of the energy storage element is another contact plate part 122, which substantially covers the (lower) second end face 104b of the electrode winding 104. In this embodiment, this contact plate part 122 is welded to the free edge strip 109b of the cathode. During assembly, the contact plate part 122 is pressed against the second end face 104b, so that the protrusion formed by the edge strip 109b deforms in a manner not shown here.
[0149] The contact plate part 122 is in direct contact with the base 101a of the housing and can be connected to it, in particular by welding. The welding can, for example, be carried out through the base 101a using a laser.
[0150] The orientation of the polarity of the energy storage element can of course also be reversed.
[0151] The housing also includes a plastic seal 103, which surrounds the edge of the lid 102 and electrically insulates the metallic components of the lid 102 from the housing cup 101. At the same time, it contributes to sealing the housing.
[0152] By pressing the contact sheet parts 112 and 122 against the end faces of the electrode winding 104 during the attachment of the contact sheet parts to the end faces 104a and 104b, a compression (not shown here) occurs and, with respect to the longitudinal extent of the electrode winding 104, a compression of the protrusions formed by the free edge strips 106b and 109b of the current collectors occurs in the axial direction.
[0153] The resulting energy storage cell 100 therefore comprises an electrode-separator assembly 104 with axially compressed protrusions formed by the free edge strips 106b and 109b of the current collectors.
[0154] Additionally, the outer windings of the free edge strip(s) of the current collector(s) can be selectively bent radially from the outside inwards, as indicated in Fig. 2 for the upper end face region 104a. This bending can be carried out, for example, by bending the outer free windings of the free edge strip of the electrode current collector radially inwards and, moreover, by pressing them together with the radially inner windings of the free edge strip when the contact plate part 112 is placed on top before welding. For example, the edge strip can be bent at an angle in the range of 30–90°. In preferred embodiments, the edge strip can also be cut for this purpose.
[0155] Compression occurs when the contact plate parts 112 and 122 are pressed onto the free edge strips 106b, 109b of the current collectors in such a way that they are deformed. In many cases, this does not result in a directed bending, but rather in an undirected compression. Thus, sections of the edge strip can be bent radially outwards and other sections radially inwards. Both the bending and the compression result in a contact surface formed by a protrusion that is compacted or hardened as a result of the bending and / or compression.
[0156] In general terms, an axially compressed protrusion has higher stability and load-bearing capacity against forces acting on the compressed protrusion in the axial direction than would be the case for a protrusion in an unloaded winding configuration.
[0157] The compressed protrusion of the current collectors has a smaller axial extent than a protrusion in the aforementioned winding configuration with uncompressed or unloaded protrusions. The axial extent of an axially compressed protrusion is, in particular, between 10% and 80%, preferably between 20% and 60%, more preferably between 30% and 50%, and further preferably between 35% and 45% of the axial extent of a protrusion in the unloaded winding configuration or before crimping. Optionally, the compressed protrusion can also be compressed to an axial extent that is less than 10% of the axial extent of the protrusion in the unloaded winding configuration.
[0158] Fig. 3 illustrates a conventional method of manufacturing the electrode winding 104 with contact plate parts 112 and 122 welded to its end faces. The electrode winding is placed along its longitudinal extent onto a support (carrier) 200. The contact plate parts 112 and 122 are pressed and simultaneously welded to the end faces of the electrode winding 104 from both sides, preferably using a laser. The contact plate parts 112 and 122 form a positive connection with the free edge strips 106b and 109b of the current collectors. As a result of the contact pressure, the free edge strips 106b and 109b of the current collectors, which form a protrusion, deform. This uncontrolled deformation of the protrusions can lead to undesirable effects. Even slight deformation results in unused dead space in the area of the end faces of the electrode winding.Excessive deformation poses a risk of damaging the separator, which can lead to an internal short circuit.
[0159] Fig. 4 illustrates the method according to the invention. Here, the electrode winding 104 is first axially fixed and thus stabilized at the circumference of the outer surface or at the circumference of the winding shell by radial clamping using a clamping device 300, before the contact plate parts 112 and 122 are pressed and welded to the end faces of the electrode winding 104 from both sides. A multi-segment chuck can be used as the clamping device 300. Fig. 5 illustrates the measurement of a plurality of electrode windings 104 before and after the pressing and welding of the contact plate parts according to the method according to the invention. In this embodiment, the electrode windings are intended for the production of a lithium-ion cell with a form factor of 18650. The outer surface of the electrode winding 104 is formed by a plastic film on which a writing area 150 and an imprint 160 with a serial counter are provided.
[0160] On the right side of Fig. 5, the attack zone 310 of the clamping device (e.g. a chuck) for the axial fixation of the electrode winding 104 during the execution of the method according to the invention is indicated by a frame shown.
[0161] On the left side of the figure, the electrode winding 104 is illustrated with the protrusions formed by the free edge strips 109b and 106b of the current collectors before crimping and welding to the contact plate parts. The measured longitudinal extent of the electrode winding 104 without the contact plate parts averaged 62.0 ± 0.4 mm. The free edge strip (aluminum) on the cathode-side end face measured 3.05 ± 0.45 mm (A-side and B-side). The free edge strip (copper) on the anode-side end face measured 1.50 ± 0.25 mm (A-side) and ± 0.45 mm (B-side).
[0162] The right side of the figure illustrates the measurement of the electrode winding 104 with the pressed-on contact plate parts 112 and 122 after crimping and welding, where the thickness of the contact plate parts was 0.3 mm and 0.2 mm, respectively. The measured longitudinal extent of the electrode winding 104, including the attached contact plate parts 112 and 122, averaged 60.75 ± 0.10 mm after crimping and welding. The crimping was symmetrical, i.e., with equal pressure on both sides. This resulted in an effective crimping of the protrusions of 1.75 mm.
[0163] Based on the length of the overhangs, this resulted in a compression ratio of approximately 40%, since the total overhangs before pressing and welding the contact plates were 4.55 mm and after pressing and welding the contact plates were 2.80 mm.
[0164] With this geometry of the electrode winding, an effective compression of up to 2.25 mm would be achievable.
[0165] Extending the uncoated free edge strips of the electrode current collectors would allow for even higher effective compression ratios. This would be particularly advantageous for even larger cell formats. Figures 6, 7, and 8 illustrate, using photographic representations of the end-face areas of the electrode winding with the welded-on contact plate parts, the effects of the inventive method on the deformation in the end-face areas compared to the conventional method.
[0166] Fig. 6 shows the cathode-side compression of a 21700 form factor lithium-ion cell manufactured using a conventional method. The free edge strip of the aluminum anode current collector is only slightly deformed, resulting in a relatively large amount of unused dead space (indicated by the drawn frame) inside the cell, which does not contribute to the cell's capacity.
[0167] Figure 7 shows the cathode-side compression in the upper section and the anode-side compression in the lower section of a 21700 form factor lithium-ion cell manufactured using conventional methods. In this case, excessive deformation on the cathode side caused the free edge strips of the aluminum cathode current collector to be pressed through the separator onto the anode coating, resulting in short circuits (indicated by the frame in the upper section). On the opposite anode side, however, only slight deformation is observed, creating unused dead space (indicated by the frame in the lower section).
[0168] Fig. 8 shows, in the upper area, the cathode-side compression and, in the lower area, the anode-side compression of a lithium-ion cell with a form factor of 21700 manufactured according to the invention. In both the cathode-side and anode-side compression areas, deformation is observed to an optimal extent, with neither excessive unused dead space nor excessive compression that could lead to a short circuit (each indicated by the drawn frames).
[0169] Fig. 9 shows a perspective view of the exterior of an electrochemical energy storage element 100 in the form of a cylindrical cell. The energy storage element comprises a housing cup 101, which contains the electrode-separator assembly, and a contact plate 112 arranged on one end face, which serves as a lid. A seal 144 is arranged between the rim 101a of the housing cup 101 and the contact plate 112, electrically insulating both components and simultaneously contributing to the sealing of the housing. The contact plate 112 also carries a filling hole closure element 145, which is welded onto the contact plate 112 after electrolyte filling and hermetically seals the opening at the end face. The exterior view illustrates the compact design of the housing closure, in which the contact plate simultaneously performs the electrical contacting function and the mechanical lid function.The beads 144 contribute to mechanically stabilizing the contact surface between the contact plate part 112 and the compression body formed by the compressed free edge strips. The local stiffening created by the beads reduces undesirable elastic deflections of the contact plate and ensures a uniform force distribution across the end face of the electrode-separator assembly.
[0170] Fig. 10 shows a partially cutaway view of the electrochemical energy storage element 100 from Fig. 9, revealing the internal structure of the cell. Inside the housing cup 101, the electrode-separator assembly 104 is arranged in the form of a cylindrical coil. The contact plate part 112 sits on the upper end face of the assembly and is metallurgically welded to the free edge strip of the associated electrode. The seal 103 is located between the bent edge section 101a of the housing cup and the contact plate part 112. In the assembled state, the seal is axially compressed, ensuring electrical insulation and a reliable seal. The illustration clearly shows how the electrode-separator assembly mechanically absorbs the axial closing forces during the forming of the edge section 101a and thus serves as a counter-element for the housing closure.
Claims
- 28 - PATENT CLAIMS 1. Method for manufacturing an electrochemical energy storage element (100) with an electrode-separator assembly (104) and a housing (101, 102) comprising the following process steps: a) An electrode-separator assembly (104) in the form of a cylindrical winding with a first terminal end face (104a) and a second terminal end face (104b) and an intermediate winding sheath (104c) is provided, wherein i. the electrode-separator assembly (104) consists of ribbon-shaped electrodes (105, 108) and at least one ribbon-shaped separator (156, 157), ii. the ribbon-shaped electrodes (105, 108) and the ribbon-shaped separator (156, 157) are wound around a winding axis that defines the axial center of the winding, iii. the ribbon-shaped electrodes (105, 108) comprise at least one anode and at least one cathode, wherein the anode (105) comprises an anode current collector (106) having a strip-shaped main region (107) loaded with a layer of negative electrode material, and a free edge strip (106b) extending along a longitudinal edge (106a) of the anode current collector (106) which is not loaded with the negative electrode material, and / or the cathode (108) comprises a cathode current collector (109) having a strip-shaped main region (110) loaded with a layer of positive electrode material, and a free edge strip (109b) extending along a longitudinal edge (109a) of the cathode current collector (109) which is not loaded with the positive electrode material (110), and wherein a) the anode (105) and / or the cathode (108) are arranged within the electrode-separator assembly (104) such that the free edge strip (106b) of the anode current collector (106) protrudes from the first terminal end face (104a) forming a projection and / or the free edge strip (109b) of the cathode current collector (109) protrudes from the second terminal end face (104b) forming a projection, b) a contact plate part (112, 122) is placed on at least one of the end faces (104a, 104b) of the electrode-separator assembly, c) the at least one attached contact plate part (112, 122) is pressed onto the end face by deformation of the respective protrusion of the anode current collector (106) and / or the cathode current collector (109) and welded to the electrode separator assembly (104), d) the electrode-separator assembly (104) with the at least one contact plate part (112, 122) is inserted into a housing (101, 102), e) the electrode-separator assembly (104) with the at least one contact plate part (112, 122) is electrically contacted with the housing (101, 102), characterized in that f) the electrode-separator assembly (104) with the at least one attached contact plate part (112, 122) is axially fixed during pressing and welding in step c., and that g) axial fixation is achieved by radial clamping on the circumference of the winding jacket (104c).
2. The method of claim 1 with the following additional feature: a) Radial clamping is carried out using a jaw chuck, in particular using a multi-segment jaw chuck.
3. A method according to claim 1 or claim 2 with the following additional feature: a) The welding of the at least one contact plate part (112, 122) to the electrode separator assembly (104) is carried out by laser treatment.
4. Method according to any of the preceding claims with the following additional feature: a) A contact plate part (112, 122) is placed on each of the end faces (104a, 104b) of the electrode separator assembly (104) and pressed and welded to the respective end face.
5. Method according to claim 4 with the following additional feature: a) To press the respective contact sheet part (112, 122) against the two end faces of the electrode separator assembly (104), axial pressure is exerted on both end faces.
6. The method of claim 5 with the following additional feature: a) The axial pressure exerted on both end faces (104a, 104b) is different.
7. Method according to any of the preceding claims with the following additional feature: a) The free edge strips (106b, 109b) of the cathode current collector and / or the anode current collector are bent radially inwards at least section by section before the at least one contact plate part (112, 122) is placed. b) The electrode-separator assembly (104) is inserted into a housing cup (101) with the at least one contact plate part (112, 122), which is closed with a lid (102), wherein the contact plate part (112, 122) serves as the lid (102) and an edge section of the housing cup is bent radially inwards over the contact plate part (112, 122).
8. Electrochemical energy storage element (100), producible by a method according to any one of claims 1 to 7, comprising a) an electrode-separator assembly (104) in the form of a cylindrical winding with a first terminal end face (104a) and a second terminal end face (104b) and an intermediate winding sheath (104c), wherein i. the electrode-separator assembly (104) consists of ribbon-shaped electrodes (105, 108) and at least one ribbon-shaped separator (156, 157), ii. the ribbon-shaped electrodes (105, 108) and the ribbon-shaped separator (156, 157) are wound around a winding axis that defines the axial center of the winding, iii. the ribbon-shaped electrodes (105, 108) comprise at least one anode and at least one cathode, wherein the anode (105) comprises an anode current collector (106) having a strip-shaped main region (107) loaded with a layer of negative electrode material, and a free edge strip (106b) extending along a longitudinal edge (106a) of the anode current collector (106) which is not loaded with the negative electrode material, and / or the cathode (108) comprises a cathode current collector (109) having a strip-shaped main region (110) loaded with a layer of positive electrode material, and a free edge strip (109b) extending along a longitudinal edge (109a) of the cathode current collector (109) which is not loaded with the positive electrode material (110), and wherein the anode (105) and / or the cathode (108) within the electrode-separator assembly (104) are arranged such that the free edge strip (106b) of the anode current collector (106) protrudes from the first terminal end face (104a) forming a protrusion and / or the free edge strip (109b) of the cathode current collector (109) protrudes from the second terminal end face (104b) forming a protrusion, b) a contact plate part (112, 122) is placed on at least one of the end faces (104a, 104b) of the electrode-separator assembly, c) the free edge strip forming the overhang of the respective end face is deformed by the attached contact plate part (112, 122), and the overhang formed by the free edge strip is compressed in the axial direction by 10-75% compared to its uncompressed extent and thereby forms an axially load-bearing compression body, d) that at least one attached contact plate part (112, 122) is welded to the end face of the electrode-separator assembly (104), and e) the electrode separator assembly (104) with the at least one contact plate part (112, 122) is inserted into a housing (101, 102).
9. Electrochemical energy storage element according to claim 8 with the following additional feature: a) The deformed protrusions of the anode current collector (106) and / or the cathode current collector (109) exhibit a degree of compression of 20 to 60%, preferably 30 to 50%, and particularly preferably 40 ± 5% in the axial direction compared to their uncompressed extent.- 32 - b) The contact plate part (112, 122) is pressed against the electrode-separator assembly (104) by an axial closing pressure generated when the housing is closed.
10. Electrochemical energy storage element according to one of claims 8 or 9 with the following additional feature: a) The deformed protrusions of the anode current collector (106) and the cathode current collector (109) have an identical degree of compression.
11. Electrochemical energy storage element according to one of claims 8 to 10 with at least one of the following additional features: a) The electrochemical energy storage element (100) has a cylindrical housing, wherein the attached contact sheet part (112, 122) forms an end wall of the housing. b) The electrochemical energy storage element (100) has a cylindrical housing comprising a housing cup (101) and a lid (102), wherein the contact sheet part (112, 122) is designed as the lid (102) which closes the opening of the housing cup. c) An edge section of the housing cup (101) is bent over the contact plate part (112, 122). d) The electrochemical energy storage element (100) comprises a seal (103) which electrically insulates the contact plate part (112, 122) and the housing cup from each other. e) The seal (103) is axially compressed between the bent edge section of the housing cup (101) and the contact plate part (112, 122). f) The electrochemical energy storage element (100) is a cylindrical cell. g) The electrochemical energy storage element (100) is a cylindrical cell with a form factor of 18650 or 21700.
12. Electrochemical energy storage element according to one of claims 8 to 11 with the following additional feature: a) The contact plate part (112, 122) is stiffened by beads (144) which are embossed axially or radially into the contact plate cover. b) The contact plate part (112, 122) is welded to the deformed free edge strip.
13. Electrochemical energy storage element according to one of claims 8 to 12 with the following additional feature: a) The contact plate part (112, 122) has a filling hole which is closed by a metal part (145) which is welded onto the contact plate part (112, 122).
14. Electrochemical energy storage element according to one of claims 8 to 13 with the following additional feature: a) The housing (101, 102) includes a base with PRV functionality. b) The contact plate part (112, 122) includes PRV functionality.
15. Electrochemical energy storage element according to one of claims 8 to 14 with the following additional feature: a) The attached contact plate part (112, 122) forms a wall of the housing (101, 102).