Energy storage element

Abstract

An energy storage element (100) comprises an electrode-membrane assembly (104) consisting of a strip-shaped electrode and at least one strip-shaped membrane in the order of anode (105) / membrane (156) / cathode (108) and in the form of a cylindrical winding in which the anode (105), membrane (156) and cathode (108) are wound about a winding axis A. The anode (105) and the cathode (108) each include a current collector (106, 109) having a strip-shaped main region (107, 110) covered with an electrode material and a free edge strip (106b, 109b) along a longitudinal edge (106a, 109a) and not covered with the electrode material. The anode and cathode are arranged within the electrode-membrane assembly (104) such that a free edge strip (106b) of the anode current collector (106) protrudes from the first axial end face (104a) and a free edge strip (109b) of the cathode current collector (109) protrudes from the second axial end face (104b) of the winding. A contact sheet metal member (112) rests on one of the edge strips (106b, 109b), covers the end face (104a, 104b) from which the free edge strip projects, and is bonded to the free edge strip. A current collector (106 or 109), on the free edge strip (106b or 109b) of which a contact sheet metal member (112) is attached, is helically wound in a cylindrical winding and comprises an outer turn (181) having a maximum radius R1. The contact sheet metal member (112) has, on an end face (104a or 104b) covered by the contact sheet metal member, a maximum radial extension Emax measured from an intersection of the winding axis and the plane of the contact sheet metal member. In this case, the region of the free edge strips (106b, 109b), which is surrounded by the outer turn (181), is bent radially inward at least in sections, and Emaxt; r1 is as shown in the specification.

Description

TECHNICAL FIELD

[0001] The application described hereinafter relates to an energy storage element. BACKGROUND

[0002] An electrochemical energy storage element can convert stored chemical energy into electrical energy by means of a redox reaction. The simplest form of an electrochemical energy storage element is an electrochemical cell. An electrochemical cell comprises a positive electrode and a negative electrode, between which a separator is arranged. During discharge, electrons are released at the negative electrode as a result of an oxidation process. This generates an electronic current which can be consumed by an external electrical load, the electrochemical cell serving as an energy source for this external electrical consumer. At the same time, an ionic current corresponding to the electrode reactions occurs within the cell. This ionic current passes through the separator and is effected by means of an ionically conductive electrolyte. The separator thus prevents direct contact between the electrodes. At the same time, however, it enables charge balancing between the electrodes.

[0003] If the chemical-to-electrical energy conversion which occurs during discharge and recharge of a cell can be reversed, the cell is referred to as a secondary cell.

[0004] Today, secondary lithium-ion cells are used as energy storage elements in many applications, since they can provide a high current and have a relatively high energy density. Secondary lithium-ion cells are based on the use of lithium, which can migrate back and forth between the electrodes of the cell in the form of ions. The negative and positive electrodes of a lithium-ion cell are usually formed by so-called composite electrodes, which comprise, in addition to electrochemically active components, also electrochemically inactive components.

[0005] In principle, any material which can absorb and release lithium ions can be used as an electrochemically active component (active material) for a secondary lithium-ion cell. For the negative electrode, for example, carbon-based particles such as graphite carbon are used. Active materials for the positive electrode can include, for example, lithium cobalt oxide (LiCo02), lithium manganese oxide (LiMn204), lithium iron phosphate (LiFeP04) or derivatives thereof. The electrochemically active materials are usually contained in the electrodes in the form of particles.

[0006] As electrochemically inactive components, the composite electrodes usually comprise sheet-like and / or strip-like current collectors (for example metal foils), which serve as a carrier for the respective active material. The current collectors are usually coated with a thin layer of the respective active material. The current collectors for the negative electrode (anode current collector) can be made of, for example, copper or nickel, while the current collectors for the positive electrode (cathode current collector) can be made of, for example, aluminum.

[0007] Additionally, as electrochemically inactive components, the electrodes can include electrode binders (e.g., polyvinylidene fluoride (PVDF) or other polymers such as carboxymethyl cellulose), conductivity enhancing additives, and other additives. The electrode binders ensure the mechanical stability of the electrodes and, typically, also ensure the adhesion of the active materials to the current collectors.

[0008] As electrolytes, lithium-ion battery cells typically comprise a solution of a lithium salt (such as lithium hexafluorophosphate (LiPF6)) in an organic solvent (e.g., ethers and esters of carbonic acid).

[0009] During the manufacturing of lithium-ion battery cells, the composite electrodes are typically combined with one or more separators to form an electrode-separator assembly. The electrodes and the separators are typically (but not necessarily) connected to each other under pressure, also by lamination or gluing. The basic functionality of the battery cell can then be established by impregnating the assembly with an electrolyte.

[0010] In many embodiments, the electrode-separator assembly is formed or processed in the form of a winding. In a first case, for example, strip-shaped positive and negative electrodes and at least one strip-shaped separator are fed individually to a winding machine and wound into a winding in the helical order positive electrode / separator / negative electrode. In a second case, the strip-shaped positive and negative electrodes and the at least one strip-shaped separator are first connected to form an electrode-separator assembly, for example by applying the pressure mentioned earlier. In a further step, the assembly is then wound.

[0011] For applications in the automotive industry, for electric bicycles, or for other applications with high energy requirements, such as in power tools, lithium-ion battery cells with the highest possible energy density can be charged and discharged at high currents.

[0012] Battery cells for the aforementioned applications are typically formed as cylindrical round battery cells, for example with a size specification of 21 x 70 (diameter mm). This type of battery cell always comprises an electrode-separator assembly in the form of a winding. Modern lithium-ion battery cells of this size specification can achieve an energy density of up to 270 Wh / kg.

[0013] The electrical contacting of the electrodes of energy storage elements poses a challenge. For example, in a round battery cell with a size specification of 21 x 70, the electrodes of the winding have to be electrically connected to the electrode posts of the respective housing.

[0014] The classical approach used here is the so-called "tab design". A strip of metal has one end ("tab") welded to the electrode and the other end is connected to the functional part of a CID (current interrupt device), for example integrated into a multi-piece cover of the metal housing. An example of this is described in US 7432010 B2.

[0015] The tab design has many weaknesses. One problem is that the tab must be relatively long, because it can only be welded to the inside of the cover before the housing is closed. And when the housing is closed, the tab must be folded at least once, which is usually not easy to achieve in production. Furthermore, the folded tab occupies space inside the housing that is no longer available for electrochemically active material, and the tab itself is a bottleneck in terms of current flowing into and out of the housing, but also in terms of heat dissipation. When an electrochemical cell operates, heat is generated in the electrodes, which must be dissipated. This is difficult when only the tab is available as a thermal bridge.

[0016] In recent years, work has increased on lithium-ion cells in which the so-called "tabless design" is used to contact the electrodes. This design completely eliminates the use of tabs. Instead, the electrode-separator assembly is manufactured from a strip-shaped electrode and a separator in the form of a jellyroll, wherein the electrode has metal current collectors that have an uncoated edge strip protruding from the jellyroll at the end face. A disc-shaped contact metal sheet member can be welded to the longitudinal edge there, as described for example in WO 2017 / 215900 A1. This can make the current collectors, and thus the associated electrodes, electrically contactable over their entire length. This significantly reduces the internal resistance within the cell. As a result, large currents can be absorbed more efficiently, and heat can also be dissipated more efficiently from the jellyroll.

[0017] KR 20230073960 A describes a complex process for cutting the uncoated edge of the current collector transversely to the longitudinal direction of the current collector, thereby forming a plurality of individual tabs. In the jellyroll, these tabs can be bent radially inwards. They then form a substantially closed end face to which a disc-shaped contact sheet of the disc-shaped contact sheet known from WO 2017 / 215900 A1 can be fixed.

[0018] For assembly and safety reasons, the disc-shaped contact sheet component should not protrude beyond the edge of the end face. Otherwise, the risk of undesirable contact between the contact sheet component and the battery cell casing is too great. Furthermore, when welding to the contact sheet component, there are sometimes high individual part tolerances and limited positioning accuracy. All of this means that the diameter of the contact sheet component must be smaller than the diameter of the winding. In addition, when welding the contact sheet component, weld positioning is also affected by certain manufacturing tolerances, meaning that welding cannot proceed to the outer edge of the contact sheet component. Therefore, the outer turns of the electrode winding cannot be material-bonded to the contact sheet component and may not even be in direct contact with it, leading to increased internal resistance. Summary of the Invention

[0019] The object of the present invention is to provide an energy storage element characterized by high energy density and low internal resistance, wherein the problems described herein do not occur.

[0020] This objective is achieved by an energy storage element having the features of claim 1. Preferred embodiments of the invention are found in dependent claims 2 to 8.

[0021] The energy storage element according to the present invention is characterized by the following features a. to h.: a. The energy storage element includes an electrode-diaphragm assembly, which is composed of strip electrodes and at least one strip diaphragm in the order of anode / diaphragm / cathode.

[0022] b. The electrode-diaphragm assembly is in the form of a cylindrical wound member having a first axial end face and a second axial end face, and a wound member sheath between the first axial end face and the second axial end face, wherein the anode, diaphragm and cathode are wound around a winding axis A that defines the axial center of the wound member.

[0023] c. The anode of the electrode-diaphragm assembly includes an anode current collector having a strip-shaped main region and a free edge strip, the strip-shaped main region being loaded with a layer of negative electrode material, and the free edge strip extending along the longitudinal edge of the anode current collector and not loaded with negative electrode material.

[0024] d. The cathode of the electrode-diaphragm assembly includes a cathode current collector having a strip-shaped main region and a free edge strip, the strip-shaped main region being loaded with a layer of positive electrode material, and the free edge strip extending along the longitudinal edge of the cathode current collector and not loaded with positive electrode material.

[0025] e. The anode and cathode are arranged within the electrode-diaphragm assembly such that the free edge strip of the anode current collector protrudes from the first axial end face, and the free edge strip of the cathode current collector protrudes from the second axial end face.

[0026] f. The energy storage element includes a contact metal sheet component. - It rests against the free edge strip of the anode current collector and covers the first axial end face, and the material is bonded to the free edge strip of the anode current collector, or - It rests against the free edge strip of the cathode current collector and at least partially covers the second axial end face, and the material is bonded to the free edge strip of the cathode current collector.

[0027] g. The current collector, which has a contact metal sheet member attached to its free edge strip, is spirally wound in a cylindrical winding and includes an outer turn with a maximum radius R1.

[0028] h. The contact metal sheet member has a maximum radial extension E on the end face covered by the contact metal sheet member, measured from the intersection point of the winding axis and the plane of the contact metal sheet member. max .

[0029] Furthermore, the energy storage element according to the present invention is characterized in that, i. The region of the free edge strip surrounded by the outer ring bends radially inward at least within the segment, and jE max <R1。

[0030] For example, this combination of features ensures that when using contact sheet members with a diameter smaller than that of the winding, the outer turn can still be material-bonded to the contact sheet member. The radial bending of the free edge strip reduces the diameter of the outer turn at least in the section, allowing the longitudinal edge of the free edge strip to also be covered by the contact sheet member.

[0031] Preferably, the free edge strips extending along the longitudinal edge of the current collector have a continuous, uniform width in the region surrounded by the outer ring. This distinguishes it from the edge strips of the current collector according to KR 20230073960 A, whose width varies in the longitudinal direction due to the formation of the stand-up pieces.

[0032] Preferably, the free edge strip extending along the longitudinal edge of the current collector is not cut transversely or perpendicularly to the longitudinal direction of the current collector in the area surrounded by the outer ring.

[0033] The area of ​​the free edge strip surrounded by the outer ring is particularly preferably radially inward along its entire length.

[0034] According to KR 20230073960 A, the complex formation of the vertical plates is not a prerequisite for the effective connection of the disc-shaped contact plates.

[0035] Clarification: The maximum radius R1 does not refer to the curved edge region, but to the region of the current collector that is not radially inwardly curved, or more precisely, to the outer turn of the current collector. Thus, the maximum radius R1 corresponds to, for example, the maximum radius of the outer turn in the main region coated with the electrode material. In a finished battery cell, this can be easily determined, for example, by using a CT scan to measure the maximum diameter of the outer turn and dividing it by 2.

[0036] CT scans can also be used to determine the position of the winding axis A. For example, two straight lines perpendicular to each other can be placed in two cross-sections of the wound cylindrical electrode-separator assembly such that they intersect the wound part at the maximum diameter of the wound part. These straight lines intersect at the axial center of the wound part and thus can also define the winding axis A.

[0037] The free edge strip of the current collector also includes a longitudinal edge along which the current collector extends. Depending on the degree of deformation of the free edge strip after radial bending and the placement of the contact metal sheet member on the free edge strip, the contact metal sheet member can also abut only on the longitudinal edge without directly contacting other regions of the free edge strip.

[0038] The longitudinal edge preferably does not have incisions and / or interruptions.

[0039] Particularly preferably, not only the region of the free edge strip surrounded by the outer turn is radially inwardly curved over its entire length. More precisely, the energy storage element according to the invention preferably has at least one of the following additional features a. and b.: a. The current collector against which the contact metal sheet member abuts on its free edge strip has n additional turns adjacent to the outer turn in the direction of the winding axis A, each additional turn having a maximum radius <R1 and >E max , where each additional turn includes a region of the free edge strip that is at least in sections radially inwardly curved.

[0040] b. n = 2 to 30.

[0041] Thus, preferably, the additional turns adjacent to the outer turn can also have a radially inwardly curved edge region.

[0042] Preferably, the immediately preceding features a. and b. are implemented in combination.

[0043] Preferably, the free edge strip extending along the longitudinal edge of the current collector has a continuous and uniform width in the region surrounded by the additional turns. Particularly preferably, the free edge strip extending along the longitudinal edge of the current collector has a continuous and uniform width in the region surrounded by the outer turn and in the region surrounded by the additional turns.

[0044] Preferably, the free edge strip extending along the longitudinal edge of the current collector is not cut transversely or perpendicularly to the longitudinal direction of the current collector in the area surrounded by the additional turns. Particularly preferably, the free edge strip extending along the longitudinal edge of the current collector is not cut transversely or perpendicularly to the longitudinal direction of the current collector in the area surrounded by the outer turn and in the area surrounded by the additional turns.

[0045] The area of the free edge strip surrounded by the additional turns is also preferably bent radially inwards over its entire length.

[0046] In this case, a turn is understood as a complete 360° rotation of the current collector around the winding axis A. The outer turn is the first turn of the winding starting from the outer end of the current collector. This is followed by the additional turns in the direction of the winding axis A. A circumferential rotation of 720° around the axis A corresponds to, for example, two complete turns.

[0047] In a preferred further development, the energy storage element according to the invention has at least one of the following features a. to e. immediately following: a. The current collector against which the contact metal sheet member abuts on its free edge strip has another turn adjacent to the outer turn in the direction of the winding axis A, which turn has a maximum radius R2, where R2 < R1 and E max < R2, and the area of the free edge strip surrounded by the turn with radius R2 is bent radially inwards at least in sections.

[0048] b. The current collector against which the contact metal sheet member abuts on its free edge strip has another turn adjacent to the turn with the maximum radius R2 in the direction of the winding axis A, which turn has a maximum radius R3, where R3 < R2 and E max < R3, and the area of the free edge strip surrounded by the turn with radius R3 is bent radially inwards at least in sections.

[0049] c. The current collector against which the contact metal sheet member abuts on its free edge strip has another turn adjacent to the turn with the maximum radius R3 in the direction of the winding axis A, which turn has a maximum radius R4, where R4 < R3 and E max < R4, and the area of the free edge strip surrounded by the turn with radius R4 is bent radially inwards at least in sections.

[0050] d. The current collector against which the contact metal sheet member abuts on its free edge strip has another turn adjacent to the turn with the maximum radius R4 in the direction of the winding axis A, which turn has a maximum radius R5, where R5 < R4 and E max < R5, and the area of the free edge strip surrounded by the turn with radius R5 is bent radially inwards at least in sections.

[0051] e. The current collector against which the contact metal sheet member abuts on its free edge strip has another turn adjacent to the turn with the maximum radius R5 in the direction of the winding axis A, and this other turn has a maximum radius R6, where R6 < R5 and E max < R6, and the region of the free edge strip surrounded by the turn with the radius R6 is radially bent inwardly at least in sections.

[0052] Preferably, the free edge strip extending along the longitudinal edge of the current collector has a width of at least 1 mm in the region surrounded by the turns having the following radii: - R2 - R3 - R4 - R5 -R6 Including the above-mentioned continuous uniform width, in particular the same continuous uniform width as that of the outer turn with the radius R1.

[0053] Preferably, the free edge strip extending along the longitudinal edge of the current collector is not cut transversely or perpendicularly to the longitudinal direction of the current collector, even in the region surrounded by these turns.

[0054] In some particularly preferred embodiments, in the energy storage element according to the invention, not only the free edge strips of the outer turn and the adjacent turns are bent inwardly. More precisely, it may be particularly advantageous if the free edge strip of the inner turn is also bent, i.e., radially outwardly, i.e., in a direction opposite to the bending direction of the free edge strip of the outer turn.

[0055] In a preferred further development, the energy storage element according to the invention has the following features a. to d. immediately following: a. The electrode-separator assembly in the form of a cylindrical winding has an axial cavity that can be accessed via a hole in the end face of the winding.

[0056] b. The winding axis A is located at the center of the axial cavity.

[0057] c. The current collector against which the contact metal sheet member abuts on its free edge strip is spirally wound in the cylindrical winding and has the innermost turn surrounding the axial cavity.

[0058] d. The region of the free edge strip surrounded by the innermost turn is radially bent outwardly at least in sections, preferably over its entire length.

[0059] Features a., c. and d. are preferably implemented in combination. Features a. to d. are particularly preferably implemented in combination.

[0060] It should be emphasized that this embodiment can also be implemented independently of features h., i., and j., and in particular independently of features i. and j. Therefore, this specification also discloses an energy storage element in which only the free edge strip of the inner turn is bent.

[0061] This approach has been shown to be suitable for facilitating the formation of a material bond between the current collector and the contact metal sheet component, particularly through welding.

[0062] Particularly preferred is that not only does the region of the free edge strip surrounded by the innermost turn curve radially outward. More precisely, the energy storage element according to the invention preferably has at least one of the following additional features a. and b.: a. The current collector with a contact metal sheet attached to its free edge strip has an additional contact metal sheet attached to the innermost turn in the direction of the outer turn. m One turn.

[0063] b. The area of ​​the free edge strip surrounded by these additional turns bends radially outward, at least in the section, preferably along its entire length.

[0064] Therefore, it is preferable that the other turns adjacent to the innermost turn may also have free edge strips that curve radially outward.

[0065] Preferably, features a and b that immediately follow are implemented in combination.

[0066] The preferred option is m = 2 to 30. Particularly preferred are... m = 2 to 15.

[0067] Preferably, the free edge strips extending along the longitudinal edge of the current collector are not cut transversely or perpendicularly to the longitudinal direction of the current collector, even in the area surrounded by these turns.

[0068] In a preferred embodiment, the energy storage element according to the invention is characterized by at least one of the following additional features a to c: a. There is at least one material bond between the contact metal sheet component and the free edge strip on which the contact metal sheet component rests.

[0069] b. The material bond between the contact metal sheet component and the free edge strip on which the contact metal sheet component rests is at least one of welding, fusion joint or adhesive bonding.

[0070] c. The at least one material bond exists between the contact metal sheet member and the area surrounded by the outer ring of the free edge strip.

[0071] Particularly preferred is that the at least one material bond also exists between the contact metal sheet member and at least one additional region of the free edge strip, the at least one additional region including a turn connected to the outer turn on the winding axis, i.e., at least one of the turns having maximum radii R2, R3, R4 and R5.

[0072] Ideally, as many turns of the current collector as possible should be bonded to the contact metal sheet component by material, such as all five outer turns with the maximum radii R1 to R5 listed above.

[0073] Preferably, the at least one material combination is at least one welded connection in the form of a weld and / or a weld point.

[0074] The above-described bonding can be achieved by using an adhesive with conductive properties to connect the free edge strip and the contact metal sheet component. Such adhesives are known, for example, from printed circuit board technology.

[0075] Fusion joints are formed by melting solder and allowing it to solidify upon contact with the free edge strip and the contact metal sheet component.

[0076] The contact sheet component can generally have a variety of geometries. However, it is particularly preferred that the contact sheet component is characterized by one of the following features a. or b.: a. The contact metal sheet member is formed as a disc with a circular perimeter: This embodiment is particularly preferred because the geometry of the contact metal sheet member corresponds to the geometry of the end face to be covered. Of course, deviations from a perfect circular shape are conceivable; for example, the disc may have recesses in the edge region, which can serve as positioning aids when the contact metal sheet member is placed on the end face. It should be noted that when the disc is centered on the corresponding end face, E max This corresponds to the maximum radius of the disk.

[0077] b. The contact sheet member includes a central region connected to an extension extending toward an edge facing the end face: when the contact sheet member is centered on the end face, the center of the contact sheet member is located at the intersection of the plane of the contact sheet member and the winding axis A. The extension is preferably a strip-shaped extension.

[0078] The following lists the further preferred features a. to f.: a. The contact metal sheet component has a thickness in the range of 50 μm to 600 μm, preferably in the range of 150 μm to 350 μm.

[0079] b. The contact metal sheet component has two opposing flat sides and extends essentially in only one dimension.

[0080] c. The size of the contact metal sheet member is set such that the contact metal sheet member covers at least 25%, preferably at least 50%, and particularly preferably at least 75% of the end face, and the free edge strip of the corresponding current collector connected to the contact metal sheet member protrudes from the end face.

[0081] d. The contact metal sheet component has at least one opening, particularly at least one hole and / or at least one slot.

[0082] e. The contact metal sheet member has at least one solder bead that is elongated recessed on one flat side of the contact metal sheet member and elongated raised on the opposite flat side, wherein preferably, the contact metal sheet member rests against the free edge strip of the corresponding current collector.

[0083] f. The contact metal sheet component is welded to the free edge strip of the current collector in the area of ​​the solder ball, particularly via one or more welds and / or solder joints arranged in the solder ball.

[0084] Features a., b., and c., or combinations of features a. to d., are particularly preferred. In other embodiments, features a., c., e., and f., or features a., c., d., e., and f., are implemented in combination.

[0085] Extensive coverage of the end face is important for thermal management of the energy storage element according to the invention. Larger coverage makes it more likely to contact the longest possible segment of the first longitudinal edge of the corresponding current collector. Therefore, heat generated in the electrode-diaphragm assembly can be efficiently dissipated via the contact metal sheet members.

[0086] In embodiments of the contact metal sheet member having the aforementioned solder beads, it may be advantageous to pre-treat the longitudinal edge of the current collector before attaching the contact metal sheet member to create a recess on the longitudinal edge corresponding to the solder beads, which facilitates the attachment and (if necessary) positioning of the contact metal sheet member.

[0087] Depending on the pressure applied when the contact metal sheet component is placed on the edge of the current collector, non-directional deformation of the longitudinal edge may also occur.

[0088] At least one hole and / or at least one slot can, for example, help fill the electrolyte and / or counteract the stress generated by the heat load during welding.

[0089] Housing and housing closure The energy storage element according to the present invention is further characterized by at least one of the following features: a. The energy storage element includes a hermetically and liquidally sealed housing, the hermetically and liquidally sealed housing including a metal housing cup and a lid, the metal housing cup having a circular bottom and a circular opening at a terminal end, the lid having a circular edge that closes the circular opening, and the hermetically and liquidally sealed housing encapsulating the internal space in which an electrode-diaphragm assembly is disposed.

[0090] b. The cover is formed as a cover assembly, which includes a metal disc and a pole cap that are in electrical contact with each other and in direct mechanical contact.

[0091] c. The cover assembly includes a seal fitted onto its edge.

[0092] Features a to c that immediately follow are preferably implemented in combination.

[0093] The circular opening of the shell cup can be closed using conventional sealing methods with the aid of a cap. Flange closure is particularly preferred. In this process, the edge of the shell cup is bent radially inward while the seal is compressed in the manner described above.

[0094] In a further preferred development, the energy storage element is characterized by the following features a. and b.: a. The shell cup comprises, in axial order, a bottom, a central section, and a closed section, wherein, - The central section is cylindrical and forms a wound portion of the electrode-diaphragm assembly. The wound portion sheath contacts the interior of the housing cup, and... - In the enclosed section, the annular seal presses into contact with the edge of the cap and the interior of the housing cup, and b. The shell cup has an opening edge defining a circular opening in the closed section, the opening edge being radially inwardly curved on the edge of the cap sealed by the seal, and the cap including the seal is secured in a form-fitting manner in the circular opening of the shell cup.

[0095] The electrode-diaphragm assembly is preferably in direct contact with the interior of the housing cup. Particularly preferred is that the cap rests directly against the interior of the housing cup. However, in some embodiments, it may be proposed to electrically insulate the interior, for example, by means of a membrane. In this case, the electrode-diaphragm assembly is connected to the inner wall via the membrane.

[0096] The aforementioned winding axis A preferably coincides with the axial center of the housing, particularly the cylindrical central section. Therefore, the winding axis A can also preferably be defined as an axis passing through the center of the circular bottom of the housing and the center of the cover with a circular edge.

[0097] The energy storage element according to the invention is characterized in particular by at least one of the following features a to c: a. The central section and the closed section are separated by a recessed portion that extends annularly around the outer side of the shell cup.

[0098] b. The shell cup has the same maximum outer diameter in the central section and the closed section.

[0099] c. In the recessed region, the outer diameter of the shell cup is reduced by 4 to 20 times the wall thickness of the shell cup in that region.

[0100] Preferably, at least the immediately preceding features a. and b. are implemented in combination. Particularly preferred is that all three immediately preceding features a. to c. are implemented in combination.

[0101] Preferably, the annular seal is compressed within the closed section. The annular seal is preferably pressed radially against the circular edge of the cap.

[0102] The choice of housing is not necessarily a fundamental feature of this invention. The cap can also be fixed to the opening of the housing cup by welding, and an electrode bushing can be provided in the cap or at another point on the housing.

[0103] The bottom of the shell cup is preferably round. The shell cup is usually formed by deep drawing. However, the cup can also be formed by welding the bottom into a tubular half.

[0104] The energy storage element according to the invention is preferably formed as a cylindrical battery cell. The height of the cylindrical battery cell is preferably in the range of 50 mm to 150 mm. The diameter of the cylindrical battery cell is preferably in the range of 15 mm to 60 mm. Cylindrical battery cells with these dimensions are suitable, for example, for supplying power to electric drive systems in motor vehicles.

[0105] In many cases, after the electrode-diaphragm assembly has been inserted, one of the end faces of the electrode-diaphragm assembly rests directly against the bottom of the housing cup. It may then be necessary to bring the free edge strip of the current collector protruding from this end face into contact with the bottom of the housing. This can be accomplished, for example, by welding through the bottom of the housing using a laser. In other possible embodiments, a suitable contact metal member is applied to this end face prior to step e, such that after insertion, only this contact metal member needs to contact the housing cup or the bottom of the housing cup, for example, via a weld joint. The weld joint between the contact metal member and the bottom can be created, for example, by resistance welding. For this purpose, a welding electrode can be guided through an axial cavity in the winding, and a second welding electrode can be pressed against the bottom from the outside.

[0106] The contact metal plate component pointing towards the opening of the housing cup is preferably electrically connected to the cap, for example, by direct welding to a component of the cap or via an electrical conductor. If the cap is welded into the opening, electrical contact with the pole bushing is required.

[0107] Before or after enclosing the housing, the electrode-separator assembly can be impregnated with a suitable electrolyte. In a second variant, the electrolyte has to be metered through suitable holes in the housing and then the holes are closed.

[0108] Embodiments of lithium ion energy storage elements In a particularly preferred embodiment of the invention, the energy storage element according to the invention is based on lithium-ion technology.

[0109] Basically, all electrode materials known for secondary lithium-ion battery cells can be used for the electrodes of the energy storage element.

[0110] In the negative electrode, carbon-based particles (such as graphite carbon or non-graphite carbon materials) capable of intercalating lithium (preferably also in particulate form) can be used as the active material. Alternatively or additionally, lithium titanate (Li4Ti5O 12 ) or derivatives thereof can be included in the negative electrode, preferably also in particulate form. Additionally, the negative electrode can comprise at least one material from the group including: silicon, aluminum, tin, antimony, or compounds or alloys of these materials that can reversibly store and release lithium (such as silicon oxide (especially SiO x , where 0 < x < 2), optionally in combination with a carbon-based active material). Tin, aluminum, antimony, and silicon can form intermetallic phases with lithium. The lithium absorption capacity is many times that of graphite or similar materials, especially in the case of silicon. Mixtures of silicon-based and carbon-based storage materials are often used. Thin anodes made of metallic lithium are also suitable.

[0111] For the positive electrode, active materials such as lithium metal oxide compounds and lithium metal phosphate compounds (such as LiCoO2 and LiFePO4) are suitable. Lithium nickel manganese cobalt oxide (NMC) with the chemical formula LiNi x Mn y Co z O2 (where x + y + z is typically 1), lithium manganese spinel (LMO) with the chemical formula LiMn2O4, or lithium nickel cobalt aluminum oxide (NCA) with the chemical formula LiNi x Co y Al z O2 (where x + y + z is typically 1). Derivatives thereof can be used, such as lithium nickel manganese cobalt aluminum oxide (NMCA) with the chemical formula Li 1.11 (Ni 0.40 Mn 0.39 Co 0.16 Al 0.05 ) 0.89 O2 or Li 1+x M-O compounds, and / or mixtures of the materials mentioned above. The cathode active material is also preferably used in particulate form.

[0112] Furthermore, the electrodes of the energy storage element preferably include electrode binders and / or additives to improve conductivity. The active material is preferably embedded in the matrix of the electrode binder, wherein adjacent particles in the matrix are preferably in direct contact with each other. Conductive agents have the function of increasing the conductivity of the electrodes. Conventional electrode binders are based on, for example, polyvinylidene fluoride (PVDF), lithium polyacrylate, styrene-butadiene rubber, or carboxymethyl cellulose, or mixtures of different binders. Conventional conductive agents are carbon black, fine graphite, carbon fibers, carbon nanotubes, and metal powders.

[0113] The energy storage element preferably includes an electrolyte, and in the case of a lithium-ion battery cell, particularly an electrolyte based on at least one lithium salt (such as lithium hexafluorophosphate (LiPF6)) dissolved in an organic solvent (e.g., organic carbonates or mixtures of cyclic ethers or nitriles such as THF). Other lithium salts that can be used include lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(oxalic acid)borate (LiBOB).

[0114] The nominal capacity of the lithium-ion-based energy storage element formed as a cylindrical spherical battery cell is preferably up to 15,000 mAh. In the case of a 21 × 70 size, the spherical battery cell in the lithium-ion battery cell embodiment preferably has a nominal capacity in the range of 1500 mAh to 7000 mAh, particularly preferably in the range of 3000 mAh to 5500 mAh. In the case of a 18 × 65 size, the spherical battery cell in the lithium-ion battery cell embodiment preferably has a nominal capacity in the range of 1000 mAh to 5000 mAh, particularly preferably in the range of 2000 mAh to 4000 mAh.

[0115] In the European Union, strict regulations govern manufacturer information regarding the nominal capacity of secondary batteries. For example, information on the nominal capacity of secondary nickel-cadmium batteries must be based on measurements performed according to standards IEC / EN 61951-1 and IEC / EN 60622; information on the nominal capacity of secondary nickel-metal hydride batteries must be based on measurements performed according to standard IEC / EN 61951-2; information on the nominal capacity of secondary lithium batteries must be based on measurements performed according to standard IEC / EN 61960; and information on the nominal capacity of secondary lead-acid batteries must be based on measurements performed according to standard IEC / EN 61056-1. Any information regarding nominal capacity in this application is also preferably based on these standards.

[0116] Embodiments based on sodium ions In other embodiments, the energy storage element may also be a sodium-ion battery cell, a potassium-ion battery cell, a calcium-ion battery cell, a magnesium-ion battery cell, or an aluminum-ion battery cell. Among these variations, energy storage elements having the chemical properties of sodium-ion battery cells are particularly preferred.

[0117] Preferably, the sodium ion-based energy storage element includes an electrolyte comprising at least one of the following solvents and at least one of the following conductive salts: Organic carbonates, ethers, nitriles, and mixtures thereof are particularly suitable as solvents. Preferred examples are: - Carbonates: propylene carbonate (PC), ethylene carbonate-propylene carbonate (EC-PC), propylene carbonate-dimethyl carbonate-ethyl methyl carbonate (PC-DMC-EMC), ethylene carbonate-diethyl carbonate (EC-DEC), ethylene carbonate-dimethyl carbonate (EC-DMC), ethylene carbonate-dimethyl carbonate-ethyl methyl carbonate (EC-EMC), ethylene carbonate-dimethyl carbonate-ethyl carbonate (EC-DMC-EMC), ethylene carbonate-dimethyl carbonate-diethyl carbonate (EC-DMC-DEC) - Ethers: Tetrahydrofuran (THE), 2-Methyltetrahydrofuran, Dimethyl ether (OME), 1,4-Dioxane (DX), 1,3-Dioxolane (DOL), Diethylene glycol dimethyl ether (DEGDME), Tetraethylene glycol dimethyl ether (TEGDME) - Nitriles: Acetonitrile (ACN), Adiponitrile (AON), Gamma-Butyrolactone (GBL) It could also be trimethyl phosphate (TMP) and tri(2,2,2-trifluoroethyl) phosphate (TFP).

[0118] The preferred guiding salt is: NaPF6, sodium difluoro(oxalate)borate (NaBOB), NaBF4, sodium bis(fluorosulfonyl)imide (NaFSI), sodium 2-trifluoromethyl-4,5-dicyanoimidazolium (NaTDI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), NaAsF6, NaBF4, NaClO4, NaB(C2O4)2, NaP(C6H4O2)3, NaCF3SO3, sodium trifluoromethanesulfonate (NaTf), and Et4NBF4.

[0119] In a preferred embodiment, an additive may be added to the electrolyte. Examples of preferred additives, particularly for stabilization, are as follows: Fluorinated vinyl carbonate (FEC), trans-fluoroethylene carbonate (DFEC), vinyl sulfite (ES), vinyl carbonate (VC), bis(2,2,2-trifluoroethyl) ether (BTFE), sodium 2-trifluoromethyl-4,5-dicyanimidazolium (NaTDI), sodium bis(fluorosulfonyl)imide (NaFSI), aluminum chloride (AlCl3), vinyl sulfate (DTD), sodium difluorophosphate (NaPO2F2), sodium difluoro(oxalate)borate (NaODFB), sodium difluorodioxalate phosphate (NaDFOP), and tri(trimethylsilyl)borate (TMSB).

[0120] The negative electrode material of a sodium ion-based energy storage element is preferably at least one of the following materials: - Carbon, particularly hard carbon (pure or with nitrogen and / or phosphorus doping) or soft carbon or graphene-based materials (with N doping); carbon nanotubes, graphite -Phosphorus or sulfur (conversion anode) - Polyanionic compounds: Na2Ti3O7, Na3Ti2(PO4)3, TiP2O 7、 TiNb2O7, Na-Ti-(PO4) 3、 Na-V-(PO4)3 - Prussian blue: a sodium-poor variant (for systems with aqueous electrolytes) - Transition metal oxides: V₂O₅, MnO₂, TiO₂, Nb₂O₅, Fe₂O₃, Na₂Ti₃O₇, NaCrTiO₄, Na₄Ti₅O 12 -MXenes, where M = Ti, V, Cr, Mo or Nb and A = Al, Si and Ga, and X = C and / or N, such as Ti3C2 - Organic compounds: For example, sodium terephthalate (Na2C8H2O4).

[0121] Alternatively, a Na metal anode can be used on the anode side.

[0122] The positive electrode material of a sodium ion-based energy storage device is at least one of the following materials: - Polyanionic: NaFePO4 (triphylite type), Na2Fe(P2O7), Na4Fe3(PO4)2(P2O7), Na2FePO4F, Na / Na2[Fe 1 / 2 Mn 1 / 2 ]PO4F, Na3V2(PO4)2F3, Na3V2(PO4)3, Na4(CoMnNi)3(PO4)2P2O7, NaCoPO4, Na2CoPO4F -Silicates: Na₂MnSiO₄, Na₂FeSiO₄ - Layered oxides: NaCoO2, NaFeO2, NaNiO2, NaCrO2, NaVO2, NaTiO2, Na(FeCo)O2, Na(NiFeCo)3O2, Na(NiFeMn)O2, and Na(NiFeCoMn)O2, Na(NiMnCo)O2.

[0123] Furthermore, the electrodes of the energy storage element according to the invention preferably comprise electrode binders and / or additives to improve conductivity. The active material is preferably embedded in the matrix of the electrode binder, whereby the active material is preferably used in particulate form, and adjacent particles in the matrix are preferably in direct contact with each other. The conductive agent has the function of improving the conductivity of the electrode. Conventional electrode binders are based on, for example, polyvinylidene fluoride (PVDF), sodium polyacrylate, styrene-butadiene rubber, sodium alginate, or carboxymethyl cellulose, or mixtures of different binders. Conventional conductive agents are carbon black, fine graphite, carbon fibers, carbon nanotubes, and metal powders.

[0124] In sodium-ion-based energy storage devices, it is particularly preferred that both the anode current collector and the cathode current collector are made of aluminum or aluminum alloy. The housing, contact plates, and any other current conductors within the housing may also be made of aluminum or aluminum alloy.

[0125] Preferred embodiments of contact metal sheet members In principle, the contact metal sheet component can be electrically connected to the anode current collector or the cathode current collector.

[0126] In a particularly preferred embodiment of the invention, the contact metal sheet member electrically connected to the anode current collector is characterized by at least one of the following features a. and b.: a. The contact metal sheet component is made of nickel, or copper, or titanium, or nickel alloy, or copper alloy, or titanium alloy, or stainless steel (e.g., type 1.4303 or type 1.4404 or type SUS304), or nickel-plated copper.

[0127] b. The contact metal sheet component is made of the same material as the anode current collector.

[0128] In another particularly preferred embodiment of the invention, the contact metal sheet member electrically connected to the cathode current collector is characterized by at least one of the following features a. and b.: a. The contact metal sheet component is made of aluminum or aluminum alloy.

[0129] b. The contact metal sheet component is made of the same material as the anode current collector.

[0130] Preferred designs of electrode-separator assemblies The anode, cathode, and one or more separators of the battery cell according to the present invention preferably have the following dimensions: - Length in the range of 0.5 m to 25 m - Width in the range of 40 mm to 145 mm In an electrode-diaphragm assembly formed as a wound piece, a strip anode, a strip cathode, and one or more strip diaphragms are preferably helically wound. To manufacture the electrode-diaphragm assembly, the strip electrode and the strip diaphragm(s) are typically fed into a winding apparatus and preferably wound helically around a winding axis A. Adhesion of the electrode and diaphragm or contact at elevated temperatures is generally unnecessary. In some embodiments, the electrode and one or more diaphragms are wound onto a cylindrical or hollow cylindrical winding core, which rests against a winding mandrel and remains in the wound piece after the winding process.

[0131] The winding sleeve can be formed, for example, from a plastic film or tape. The winding sleeve can also be formed from one or more diaphragm turns.

[0132] Preferred embodiments of current collectors The current collector of the energy storage element according to the invention has the function of electrically contacting the electrochemically active components contained in the corresponding electrode material over the largest possible area. Preferably, the current collector is made of metal, or at least metallized on its surface.

[0133] The current collector preferably has substantially the same length and width as the anode and cathode of the energy storage element according to the invention.

[0134] In the case of energy storage elements formed as lithium-ion battery cells according to the present invention, metals (such as copper or nickel) or other conductive materials, particularly copper and nickel alloys or nickel-coated metals, are suitable for the anode current collector. Materials of type EN CW-004A or EN CW-008A with a copper content of at least 99.9% can be used as copper alloys. Alloys of the NiFe, NiCu, CuNi, NiCr, and NiCrFe types are particularly suitable as nickel alloys. Stainless steel is also suitable in principle, for example, type 1.4303, 1.4404, or SUS304 stainless steel.

[0135] In the case of energy storage elements formed as lithium-ion battery cells according to the present invention, aluminum or other conductive materials (including aluminum alloys) are particularly suitable as metals for cathode current collectors.

[0136] Suitable aluminum alloys for cathode current collectors include, for example, Al alloys of types 1235, 1050, 1060, 1070, 3003, 5052, Mg3, Mg212 (series 3000), and GM55. AlSi, AlCuTi, AlMgSi, AlSiMg, AlSiCu, AlCuTiMg, and AlMg are also suitable. The aluminum content of these alloys is preferably above 99.5%.

[0137] The anode current collector and / or cathode current collector are preferably strip metal foils with a thickness in the range of 4 μm to 30 μm.

[0138] Besides foil, other strip-shaped substrates (such as metal or metallized nonwovens or open-cell metal foams or porous metals) can also be used as current collectors.

[0139] The current collector is preferably coated with corresponding electrode materials on both sides.

[0140] Preferred designs of separators The diaphragm is preferably a strip of microporous plastic foil, for example, made of polyolefin. If desired, the diaphragm can be stabilized to resist thermal stress by ceramic additives or coatings.

[0141] Preferably, the longitudinal edges of one or more diaphragms form the end faces of the electrode-diaphragm assembly formed as a wound element.

[0142] Possible designs of seals Preferably, the energy storage element according to the invention is characterized by immediately following at least one of the following features a. and b.: a. The seal is made of a plastic material with a melting point >200°C, preferably >300°C, and particularly preferably >300°C and <350°C.

[0143] b. The plastic material is polyetheretherketone (PEEK), polyimide (PI), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), or polybutylene terephthalate (PBT).

[0144] Preferably, the preceding features a. and b. are implemented in combination. Attached Figure Description

[0145] Further features and advantages of the invention will be apparent from the claims and from the following description of preferred embodiments of the invention taken in conjunction with the accompanying drawings. The various features may be implemented individually or in combination with each other.

[0146] The attached diagram schematically illustrates: - Figure 1The subject of the invention is illustrated by means of two cross-sectional views of an electrode-diaphragm assembly for an energy storage element according to the invention.

[0147] - Figure 2 An embodiment of a contact metal sheet component applicable to the present invention is shown.

[0148] - Figure 3 Another embodiment of the contact metal sheet component applicable to the present invention is shown.

[0149] - Figure 4 A top view is shown of the free edge strip protruding from the end face of the current collector.

[0150] - Figure 5 The end face of the electrode-diaphragm assembly is shown, with the free edge strip of the anode current collector protruding from this end face (cross-sectional view).

[0151] - Figure 6 A cross-section of the energy storage element according to the present invention is shown.

[0152] - Figure 7 The structure of the electrode-diaphragm assembly is shown. Detailed Implementation

[0153] Figure 1 The electrode-diaphragm assemblies 104, schematically shown, are each in the form of a cylindrical wound member having a first axial end face 104a and a second axial end face 104b, and a wound member sheath 104c between the first axial end face 104a and the second axial end face 104b. In addition to the anode, each assembly includes two diaphragms and a cathode, which are wound around a winding axis A defining the axial center of the wound member. These components are not shown individually. Free edge strips belonging to the current collectors of the electrodes protrude from the end faces, with the free edge strip 106b of the anode current collector protruding from end face 104a and the free edge strip 109b of the cathode current collector protruding from end face 104b. They do not contain electrode material and can be used for electrical contact with the contact metal sheet member 112. Furthermore, they have a continuous, uniform width and are not cut transversely or perpendicularly to the longitudinal direction of the current collector.

[0154] The diagram on the left illustrates the problem this invention aims to solve. For safety reasons, a disc-shaped contact metal sheet member 112 with a diameter smaller than the maximum diameter of the winding member is selected. Correspondingly, the maximum radius R1 of the winding member is greater than the maximum radial extension E of the contact metal sheet member, measured from the intersection of the contact metal sheet member 112 and the winding axis A. max With the winding in place, the outer turn 181 or the section of the free edge strip 106b included by the outer turn is not covered by the contact metal sheet member 112.

[0155] The situation differs from that shown in the right figure for the wound component. Here, the section of the free edge strip 106b, consisting of the outer turn 181 and the adjacent turn 182, is radially bent inward, so that the turn 181 directly abuts against the bottom side of the contact metal sheet member 112. Therefore, the wound component achieves better thermal and electrical connections.

[0156] The winding shown can, for example, be configured for a 21700 type battery cell. In this case, R1 is, for example, 10 mm ± 0.8 mm, while E max For example, it is 9.75 mm ± 0.025 mm.

[0157] Figure 2 The contact metal sheet member 112 shown is formed as a disk with a circular perimeter, wherein the disk has three recesses 112c in the edge region, which can serve as positioning aids, for example, when placing the contact metal sheet member 112 on the end face of the electrode-diaphragm assembly. The disk preferably has a thickness in the range of 50 μm to 600 μm. Additionally, the disk has a central circular aperture 112d, which can be helpful during electrolyte filling. The disk includes three elongated solder beads 166 arranged in a star shape. Welding to the free edge strip of the current collector can be performed in the region of these solder beads 166.

[0158] Line 190 indicates the possible route of the edge of the axial end face of the winding of the electrode and the diaphragm. The free edge strip of the outer turn of the current collector (the free edge strip protrudes from the axial end face in the annular region between the edge of the end face and the outer edge of the contact metal sheet member 112) can only be held by the contact metal sheet member 112 when it bends radially inward.

[0159] It should be emphasized that when the disk is centrally supported on the corresponding end face, E max This corresponds to the maximum radius of the disk.

[0160] Figure 3 The contact sheet member 112 shown includes a central region 112e to which four strip-shaped extensions 112f are connected. These strip-shaped extensions extend in the direction of the end face edge when the contact sheet member 112f is abutted against the end face. When the contact sheet member is centered on the end face, the center of the contact sheet member is located at the intersection of the winding axis A and the contact sheet plane. For the purpose of explaining the invention, the outer turn 181 and the area surrounded by the turn, as well as the uncoated edge strip of the current collector, are shown in isolation. The turn 181 has its maximum radius R1 at its outer end, as do all other turns (not shown here). The maximum radial extension E of the contact sheet member 112 is also shown. max The maximum radial extension is measured from the intersection of the contact metal sheet member 112 and the winding axis.

[0161] The contact metal sheet member 112 extends substantially in only one dimension and preferably has a thickness in the range of 50 μm to 600 μm.

[0162] In the region of the strip-shaped extension, a similar configuration can be provided. Figure 3 The solder beads shown are contact metal sheet components that can be welded to the free edge strip of the current collector in this area.

[0163] Figure 4 A top view of the free edge strips protruding from the end face of the current collector is shown. Outer turns 181 to 185 are highlighted, each representing a complete 360° rotation of the current collector around the winding axis A. The outermost turn 181 begins at its end 181a and ends at line 180 after the complete 360° rotation. This is followed by turn 182, then turns 183 to 185. The edge strips are not cut transversely or perpendicularly to the longitudinal direction of the current collector.

[0164] Figure 5 A cross-section of the end face of the wound electrode-diaphragm assembly 104 is shown, from which the free edge strip 106b of the anode current collector 106 protrudes. Two outer turns 181 and 182 are radially inwardly bent and directly abut against the bottom side of the contact metal sheet member. The free edge strip is not cut transversely or perpendicularly to the longitudinal direction of the current collector.

[0165] Figure 6 The energy storage element 100 shown includes an electrode-diaphragm assembly 104 in the form of a cylindrical wound member having two axial end faces and a wound member sheath between them. A free edge strip 106b of the anode current collector 106 protrudes from the axial end face 104a. This free edge strip is not loaded with electrode material and is welded to a contact metal sheet member 112, which rests against the free edge strip 106b and covers a large portion of the first axial end face 104a. The edge strip is not cut transversely or perpendicularly to the longitudinal direction of the current collector.

[0166] Additionally, the energy storage element 100 includes a hermetically and liquidally sealed housing, comprising a metal housing cup 101 with a circular terminal opening and a cover 102 that closes the circular opening. The cover 102 includes a metal disc 113 and a terminal cap 117. The bottom side of the metal disc defines the internal space of the housing, and the terminal cap directly abuts against and is in electrical contact with the metal disc 113. An electrical conductor 133 connects the contact metal sheet member 112 and the cover 102.

[0167] The housing also includes a plastic seal 103 that surrounds the edge of the cover 102 and electrically insulates the metal parts of the cover 102 from the housing cup 101. The plastic seal also helps to seal the housing.

[0168] The section of edge strip 106b formed by outer turns 181 and 182 is bent radially inward so that it directly abuts against the bottom side of contact sheet member 112. Therefore, the winding achieves better thermal and electrical connection.

[0169] The electrode-diaphragm assembly 104 is directly attached to the bottom 101a of the housing cup 101. The free edge strip 109b is in direct contact with the bottom and can be attached to the bottom, for example, by welding. Welding can be performed using a laser through the bottom 101a.

[0170] The electrode-diaphragm assembly, in the form of a cylindrical wound element 104, has an axial cavity accessible via holes in the end faces 104a and 104b of the wound element. The winding axis A is located at the center of the axial cavity. A contact sheet member 112, abutting its free edge strip 106b, has a current collector 106 spirally wound within the cylindrical wound element and has an innermost turn 171 extending around the axial cavity. The region of the free edge strip 106b surrounded by the innermost turn 171 bends radially outward along its entire length. The same applies to the adjacent turn 172.

[0171] Figure 7 The diagram illustrates the structure of an electrode-diaphragm assembly 104, which can be part of an energy storage element according to the present invention. Assembly 104 includes a strip anode 105 having a strip anode current collector 106 having a first longitudinal edge 106a and a second longitudinal edge parallel thereto. The anode current collector 106 is a foil made of copper or nickel. The anode current collector includes a strip-shaped main region loaded with a layer of negative electrode material 107 and free edge strips 106b without electrode material 107 extending along its first longitudinal edge 106a. The free edge strips 106b have a continuous width and are thus formed. Additionally, assembly 104 includes a strip cathode 108 having a strip cathode current collector 109 having a first longitudinal edge 109a and a second longitudinal edge parallel thereto. The cathode current collector 109 is an aluminum foil. The cathode current collector includes a strip-shaped main region loaded with a layer of positive electrode material 110 and a free edge strip 109b extending along its first longitudinal edge 109a and not loaded with electrode material 110. The free edge strip 109b also has a continuous width and is thus formed. The two electrodes are shown separately in an unwound state.

[0172] The anode 105 and cathode 108 are offset from each other within the electrode-diaphragm assembly 104, such that the first longitudinal edge 106a of the anode current collector 106 protrudes from the first axial end face 104a, and the first longitudinal edge 109a of the cathode current collector 109 protrudes from the second axial end face 104b of the electrode-diaphragm assembly 104. The offset arrangement is shown in the lower left figure. Two strip-shaped diaphragms 156 and 157 are also shown there, which separate the electrodes 105 and 108 from each other within the winding.

[0173] The lower right illustration shows an electrode-diaphragm assembly 104 in a wound form, as this electrode-diaphragm assembly can be used according to... Figures 1 to 4 In one of the energy storage elements. The electrode edges 106a and 109a protruding from the end faces 104a and 104b are clearly visible. The winding sheath 104c is formed of a plastic film.

Claims

1. An energy storage element (100), said energy storage element having the following characteristics: a. The energy storage element includes an electrode-diaphragm assembly (104), which is composed of strip electrodes and at least one strip diaphragm in the order of anode (105) / diaphragm (156) / cathode (108). b. The electrode-diaphragm assembly (104) is in the form of a cylindrical wound element, the cylindrical wound element having a first axial end face (104a) and a second axial end face (104b) and a wound element sheath (104c) between the first axial end face and the second axial end face, wherein, The anode (105), the diaphragm (156), and the cathode (108) are wound around a winding axis A that defines the axial center of the wound member. c. The anode (105) of the electrode-diaphragm assembly (104) includes an anode current collector (106) having a strip-shaped main region (107) and a free edge strip (106b). The strip-shaped main region (107) is loaded with a layer of negative electrode material, and the free edge strip (106b) extends along the longitudinal edge (106a) of the anode current collector (106) and is not loaded with the negative electrode material. d. The cathode (108) of the electrode-diaphragm assembly (104) includes a cathode current collector (109) having a strip-shaped main region (110) and a free edge strip (109b), the strip-shaped main region (110) being loaded with a layer of positive electrode material, and the free edge strip (109b) extending along the longitudinal edge (109a) of the cathode current collector (109) and not loaded with the positive electrode material (110). e. The anode (105) and the cathode (108) are arranged within the electrode-diaphragm assembly (104) such that the free edge strip (106b) of the anode current collector (106) protrudes from the first axial end face (104a), and the free edge strip (109b) of the cathode current collector (109) protrudes from the second axial end face (104b). f. The energy storage element includes a contact metal sheet component (112). -Abutting against the free edge strip (106b) of the anode current collector (106) and covering the first axial end face (104a), and the material is bonded to the free edge strip (106b) of the anode current collector (106), or - It abuts against the free edge strip (109b) of the cathode current collector (109) and covers the second axial end face (104b), and the material is bonded to the free edge strip (109b) of the cathode current collector (109). in, g. The current collector (106 or 109) of the contact metal sheet member (112) abutting its free edge strip (106b or 109b) is spirally wound in the cylindrical winding and includes an outer turn (181) with a maximum radius R1, and h. The contact metal sheet member (112) has a maximum radial extension E on the end face (104a or 104b) covered by the contact metal sheet member, measured from the intersection point of the winding axis and the plane of the contact metal sheet member. max , Its features are, i. The region of the free edge strip (106b or 109b) surrounded by the outer ring (181) bends radially inward in at least one segment, and JE max <R1。 2. The energy storage element (100) according to claim 1, wherein the energy storage element has at least one of the following additional features: a. The current collector (106 or 109) against which the contact metal sheet member (112) is abutted on its free edge strip (106b or 109b) has, in the direction of the winding axis A, n additional turns, the maximum radius of each of the additional turns being < R1 and max , where Each of the additional turns includes a radially inwardly curved region in at least one segment of the free edge strip (106b or 109b). b. n = 2 to 30.

3. The energy storage element (100) according to claim 1 or claim 2, wherein the energy storage element has at least one of the following additional features: a. The current collector (106 or 109) of the contact metal sheet member (112) abutting its free edge strip (106b or 109b) has another turn (182) adjacent to the outer turn (181) in the direction of the winding axis A, the other turn having a maximum radius R2, wherein, R2 < R1 and E max < R2, and the region of the free edge strip (106b or 109b) surrounded by the turn (182) having a radius of R2 is bent radially inwards at least in one section, b. The current collector (106 or 109) against which the contact metal sheet member (112) is abutted on its free edge strip (106b or 109b) has another turn (183) adjacent to the turn (182) having the maximum radius R2 in the direction of the winding axis A, the other turn (183) having a maximum radius R3, where R3 < R2 and E max < R3, and the region of the free edge strip (106b or 109b) surrounded by the turn (183) with a radius of R3 is radially bent inward at least in one section, c. The current collector (106 or 109) against which the contact metal sheet member (112) is abutted on its free edge strip (106b or 109b) has another turn (184) adjacent to the turn (183) having the maximum radius R3 in the direction of the winding axis A, the other turn (184) having a maximum radius R4, where R4 < R3 and E max < R4, and the region of the free edge strip (106b or 109b) surrounded by the turn (184) with a radius of R4 is radially bent inward at least in one section. d. The current collector (106 or 109) against which the contact metal sheet member (112) is abutted on its free edge strip (106b or 109b) has another turn (185) adjacent to the turn (184) having the maximum radius R4 in the direction of the winding axis A, the other turn (185) having a maximum radius R5, where R5 < R4 and E max < R5, and the region of the free edge strip (106b or 109b) surrounded by the turn (185) having a radius of R5 is bent radially inward at least in one section. e. The current collector (106 or 109) against which the contact metal sheet member (112) abuts on its free edge strip (106b or 109b) has another turn (186) adjacent in the direction of the winding axis A to the turn (185) having the maximum radius R5, the other turn (186) having a maximum radius R6, the other turn (186) being adjacent in the direction of the turn axis A to the turn (185) having the maximum radius R5, where R6 < R5 and E max < R6, and the region of the free edge strip (106b or 109b) surrounded by the turn (186) with radius R6 is at least in sections bent radially inwards.

4. The energy storage element (100) according to any one of the preceding claims, wherein the energy storage element has at least one of the following additional features: a. There is at least one material bond between the contact metal sheet member (112) and the free edge strip (106b or 109b) on which the contact metal sheet member (112) abuts. b. The at least one material bond between the contact metal sheet member (112) and the free edge strip (106b or 109b) on which the contact metal sheet member (112) abuts is a welded, fused, or adhesive bond. c. The at least one material is present between the contact metal sheet member (112) and the area of ​​the free edge strip (106b or 109b) surrounded by the outer ring (181).

5. The energy storage element (100) according to any one of the preceding claims, wherein the energy storage element has at least one of the following additional features: a. The contact metal sheet component (112) is formed as a disk with a circular periphery. b. The contact metal sheet member (112) includes a central region (112a) connected to the extension (112b).

6. The energy storage element (100) according to any one of the preceding claims, wherein the energy storage element has at least one of the following additional features: a. The contact metal sheet component has a thickness in the range of 50 μm to 600 μm, preferably in the range of 150 μm to 350 μm. b. The contact metal sheet member has two opposing flat sides, and the contact metal sheet member extends substantially in only one dimension. c. The dimensions of the contact metal sheet member are set such that the contact metal sheet member covers at least 25%, preferably at least 50%, and particularly preferably at least 75% of the end face, and the free edge strip of the corresponding current collector connected to the contact metal sheet member protrudes from the end face. d. The contact metal sheet member has at least one opening (112d), particularly at least one hole and / or at least one slot. e. The contact metal sheet member has at least one solder bead, which is an elongated recess on one flat side of the contact metal sheet member and an elongated bulge on the opposite flat side, wherein preferably, the contact metal sheet member rests against the free edge strip of the corresponding current collector. f. The contact metal sheet component is welded to the free edge strip of the current collector in the area of ​​the solder ball, particularly via one or more welds and / or solder points arranged in the solder ball.

7. The energy storage element (100) according to any one of the preceding claims, wherein the energy storage element has at least one of the following additional features: a. The energy storage element includes a hermetically and liquidally sealed housing having a metal housing cup (101) and a cap (102). The metal housing cup includes a circular bottom (101a) and a circular opening at a terminal end. The cap has a circular edge (102a) that closes the circular opening. The hermetically and liquidally sealed housing encloses the internal space in which the electrode-diaphragm assembly (104) is disposed. b. The cover (102) is formed as a cover assembly, the cover assembly including a metal disc (113) and a pole cap (117) that are in electrical contact with each other and in direct mechanical contact with each other. c. The cover assembly includes a seal (103) fitted onto its edge.

8. The energy storage element (100) according to claim 7, wherein the energy storage element has at least one of the following additional features: a. The shell cup (101) comprises, in axial order, the bottom (101a), the central section (101b), and the closed section (101c), wherein, - The central section (101b) is formed in a cylindrical shape, and in the central section (101b), the winding sheath (104c) of the electrode-diaphragm assembly (104), designed as a winding element, contacts the interior of the housing cup (101), and - In the enclosed section (101c), the annular seal (103) presses into contact with the edge of the cover (102) and the interior of the housing cup (101), and b. The housing cup (101) has an opening edge (101d) in the closed section (101c) that defines the circular opening, the opening edge being radially inwardly curved on the edge of the cover (102) enclosed by the seal (103), and the opening edge securing the cover (102) containing the seal (103) in a form-fitting manner within the circular opening of the housing cup (101).

9. The energy storage element (100) according to any one of the preceding claims, wherein the energy storage element has at least one of the following additional features: a. The electrode-diaphragm assembly, in the form of the cylindrical wound element (104), has an axial cavity accessible via holes in the end faces (104a, 104b) of the wound element. b. The winding axis A is located at the center of the axial cavity. c. The current collectors (106, 109) on which the contact metal sheet member (112) is attached to the free edge strips (106b, 109b) are spirally wound in the cylindrical winding and have an innermost turn (171) extending around the axial cavity. d. The region of the free edge strip (106b, 109b) surrounded by the innermost turn (171) is radially outward in at least one segment, preferably over the entire length of the segment.

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