Energy storage element, cover assembly and production method

Abstract

An energy storage element (100) comprises an electrode-separator composite (104) with the sequence anode (105) / separator (156) / cathode (108) having a first terminal end face (104a) and a second terminal end face (104b). The energy storage element also comprises a sheet-metal contact part (112) which is supported on a longitudinal edge (106a, 109a) of a current collector (106, 109) of one of the electrodes, covers one of the end faces (104a, 104b) and is connected to this longitudinal edge. The electrode-separator composite (104) is arranged in the interior of an air- and liquid-tightly closed housing which comprises a metal housing pot (101) with a terminal circular opening and a cover (102) with a circular edge (102a), the cover closing the circular opening. Here, the cover (102), which is preferably in the form of a cover assembly, comprises a metal disc (113) with a circular edge, wherein the metal disc (113) has an inner face which delimits the interior. The invention proposes that the sheet-metal contact part (112) comprises a distance-compensating region (112d) which, in a connecting region (112e), is connected to the inner face of the metal disc (113). As an alternative to this, a sheet-metal distance-compensating part (177) can be provided, this being welded onto the sheet-metal contact part (112), wherein the sheet-metal distance-compensating part (177) comprises a distance-compensating region (177a) which, in a connecting region (177b), is connected to the inner face of the metal disc (113). The connection between the distance-compensating region (177a) and the inner face of the metal disc (113) can be formed after the housing is closed.

Description

[0001] Energy storage element, cover assembly and manufacturing process

[0002] FIELD OF APPLICATION AND STATE OF THE ART

[0003] The invention described below relates to an energy storage element, a cover assembly and a manufacturing method.

[0004] Electrochemical energy storage elements are capable of converting stored chemical energy into electrical energy through a redox reaction. The simplest form of an electrochemical energy storage element is the electrochemical cell. It comprises a positive and a negative electrode, between which a separator is arranged. During a discharge, electrons are released at the negative electrode through an oxidation process. This results in an electron current that can be tapped by an external electrical consumer, for which the electrochemical cell serves as an energy supplier. At the same time, an ion current corresponding to the electrode reaction occurs within the cell. This ion current passes through the separator and is enabled by an ion-conducting electrolyte. The separator thus prevents direct contact between the electrodes.At the same time, it enables an electrical charge balance between the electrodes.

[0005] If the discharge is reversible, meaning it is possible to reverse the conversion of chemical energy into electrical energy during the discharge and recharge the cell, it is called a secondary cell. The commonly used designation for secondary cells is the anode for the negative electrode and the cathode for the positive electrode, which refers to the discharge function of the electrochemical cell.

[0006] Secondary lithium-ion cells are now used as energy storage elements for many applications because they can provide high currents and are characterized by a comparatively high energy density. They are based on the use of lithium, which can migrate back and forth between the cell's electrodes in the form of ions. The negative and positive electrodes of a lithium-ion cell are usually formed by so-called composite electrodes, which include both electrochemically active and electrochemically inactive components.

[0007] In principle, any material capable of absorbing and releasing lithium ions can be used as electrochemically active components (active materials) for secondary lithium-ion cells. Carbon-based particles, such as graphitic carbon, are used for the negative electrode. Lithium cobalt oxide (LiCoC), lithium manganese oxide (LiMnZC), lithium iron phosphate (LiFePC), or derivatives thereof can be used as active materials for the positive electrode. The electrochemically active materials are usually contained in the electrodes in particle form.

[0008] As electrochemically inactive components, composite electrodes generally comprise a flat and / or strip-shaped current collector, for example, a metallic foil, which serves as a carrier for the respective active material. Current collectors are typically coated with thin layers of the respective active materials. 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.

[0009] Furthermore, the electrodes can contain an electrode binder (e.g., polyvinylidene fluoride (PVDF) or another polymer, such as carboxymethyl cellulose), conductivity-enhancing additives, and other additives as electrochemically inactive components. The electrode binder ensures the mechanical stability of the electrodes and often also the adhesion of the active material to the current collectors.

[0010] Lithium-ion cells usually contain solutions of lithium salts such as lithium hexafluorophosphate (Li PFs) in organic solvents (e.g. ethers and esters of carbonic acid) as electrolytes.

[0011] During the manufacture of a lithium-ion cell, the composite electrodes are generally combined with one or more separators to form an electrode-separator composite. The electrodes and separators are often, but by no means necessarily, bonded together under pressure, possibly by lamination or adhesive bonding. The basic functionality of the cell can then be achieved by impregnating the composite with the electrolyte.

[0012] In many embodiments, the electrode-separator assembly is formed in the form of a coil or processed into a coil. In the first case, for example, a strip-shaped positive electrode and a strip-shaped negative electrode, as well as at least one strip-shaped separator, are separately fed to a winding machine and spirally wound therein into a coil with the sequence positive electrode / separator / negative electrode. In the second case, a strip-shaped positive electrode and a strip-shaped negative electrode, as well as at least one strip-shaped separator, are first combined to form an electrode-separator assembly, for example, by applying the aforementioned pressure. In a further step, the assembly is then wound up.

[0013] For applications in the automotive sector, for e-bikes or for other applications with high energy requirements, such as in power tools, lithium-ion cells with the highest possible energy density are required, which at the same time are capable of being loaded with high currents during charging and discharging.

[0014] Cells for these applications are often designed as cylindrical round cells, for example, with a form factor of 21 x 70 mm (diameter times height in mm). Cells of this type always comprise an electrode-separator assembly in the form of a coil. Modern lithium-ion cells of this form factor can achieve an energy density of up to 270 Wh / kg.

[0015] One challenge is the electrical contacting of the electrodes of an energy storage element. For example, in round cells with a form factor of 21 x 70, the electrodes of the winding must be electrically connected and connected to the electrical poles of the respective housing.

[0016] The so-called "tab design" is typically used here. One end of a strip-shaped metal sheet (the "tab") is welded to an electrode, and the other end, for example, to a functional part of a CID (current interrupt device) that is integrated into a multi-part cover of a metal housing. An example of this is described in US 7432010 B2.

[0017] The function of a CID is well known to those skilled in the art. A CID ensures that the current flow in an energy storage element is interrupted in the event of a malfunction. Another safety function is the PRV (pressure relief valve). This opens when a defined pressure limit is exceeded, preventing the buildup of dangerous overpressure in an energy storage element.

[0018] The tab design has several weaknesses. One problem is that the tab must be relatively long because it can only be welded to the inside of the lid before the housing is closed. And when closing the housing, the tab must be folded at least once, which is often not easy to achieve from a production perspective. Furthermore, the folded tab takes up space within a housing that is no longer available for electrochemical active material, and the tab itself is a bottleneck in terms of current flow in and out of the housing, as well as in terms of heat dissipation. When an electrochemical cell is in operation, heat is generated in the electrodes that must be dissipated. This is difficult when only a tab is available as a thermal bridge.

[0019] In recent years, there has been increased work on lithium-ion cells in which the electrodes are contacted using a so-called "tabless design." Tabs are dispensed with entirely. Instead, electrode-separator assemblies are manufactured in the form of a coil, in which the electrodes have metallic current collectors with uncoated longitudinal edges that protrude from the coil at the ends. Metallic contact sheet parts can be welded onto the longitudinal edges, as described, for example, in WO 2017 / 215900 A1. This makes it possible to electrically contact the current collector and thus also the associated electrode over its entire length. This significantly reduces the internal resistance within the cells. Consequently, the occurrence of large currents can be absorbed much more effectively, and heat can also be dissipated more effectively from the coil.

[0020] However, the "tabless design" in its known variants does not solve all existing problems. For example, an electrical connection is still required between the cover and the contact plate part to be contacted. A suitable electrical conductor for this purpose must be as long as the aforementioned tab, since it must be welded to the cover before the housing is closed. Consequently, the conductor, like the tab, must be folded when closing the housing, creating a dead volume within the housing.

[0021] TASK AND SOLUTION

[0022] The objective of the present invention was to provide energy storage elements characterized by high energy density. At the same time, the energy storage elements to be provided should meet the highest safety standards.

[0023] This object is achieved by the energy storage element having the features of claim 1. The cover assembly according to claim 8 is also the subject of the invention. A method associated with the invention is the subject of claim 9. Preferred embodiments of the invention can be found in the dependent claims 2 to 7.

[0024] An energy storage element (100) according to the invention is characterized by the following features: a. The energy storage element comprises an electrode-separator assembly with the sequence anode / separator / cathode. b. The electrode-separator assembly is in the form of a cylindrical coil with a first terminal end face and a second terminal end face and a coil casing located therebetween. c. The anode of the electrode-separator assembly comprises an anode current collector having a first longitudinal edge and a second longitudinal edge parallel thereto and a main region loaded with a layer of negative electrode material, as well as a free edge strip extending along its first longitudinal edge and not loaded with the negative electrode material. d.The cathode of the electrode-separator assembly comprises a cathode current collector having a first longitudinal edge and a second longitudinal edge parallel thereto, a main region loaded with a layer of positive electrode material, and a free edge strip extending along its first longitudinal edge that is not loaded with the electrode material. e. The anode and the cathode are arranged within the electrode-separator assembly such that the first longitudinal edge of the anode current collector exits the first terminal end face and the first longitudinal edge of the cathode current collector exits the second terminal end face of the electrode-separator assembly. f.The energy storage element comprises a contact sheet part that sits on the first longitudinal edge of the anode current collector and covers the first terminal end face, or sits on the first longitudinal edge of the cathode current collector and covers the second terminal end face and is connected to the latter, in particular by a materially bonded connection, particularly preferably by welding, gluing, or soldering. g. The energy storage element comprises a housing that is sealed in an airtight and liquid-tight manner and comprises a metallic housing cup with a terminal circular opening and a cover with a circular edge that closes the circular opening, and that encloses an interior space in which the electrode-separator assembly is arranged. h. The cover comprises a metal disk with a circular edge, the metal disk having an inner side that delimits the interior space.The energy storage element (100) according to the invention is particularly characterized in that i. either the contact sheet part comprises a distance compensation region which is connected to the inside of the metal disc in a connection region, or a distance compensation sheet part is welded onto the contact sheet part, wherein the distance compensation sheet part comprises a distance compensation region which is connected to the inside of the metal disc in a connection region.

[0025] The connection between the distance compensation area of ​​the contact sheet part or the distance compensation sheet part on the one side and the inside of the metal disc on the other side is preferably realized by a material connection, in particular by welding or gluing or a soldered connection.

[0026] In some embodiments, the distance compensation area and the metal disc can also be connected by a positive connection, for example a rivet connection.

[0027] As explained below, the inventive design eliminates the need for a long electrical conductor for the electrical connection between the cover and the contact plate. The function of the conductor is assumed either by the spacer plate or the contact plate with the spacer compensation area. These bridge the gap between the cover and the electrode-separator assembly within the housing. Furthermore, a welded connection to the cover can be formed only after the housing is closed, which offers significant advantages in terms of optimal utilization of the available housing volume.

[0028] The connection between the distance compensation areas and the inner side of the metal disc in the connecting areas is preferably realized by said welding. The metal disc and the contact plate part or the distance compensation plate part are preferably fused together in the connecting areas.

[0029] This bonding can be achieved by bonding the spacer areas and the inner side of the metal disc with an adhesive with electrically conductive properties. Such adhesives are known, for example, from printed circuit board technology.

[0030] Said solder joint can be formed by melting a solder and allowing it to solidify upon contact with one of the spacer adjustment areas and the inner surface of the metal disc. Said riveted joint can be realized, for example, using a blind rivet pushed through a hole in the spacer adjustment area and the metal disc.

[0031] In preferred embodiments, the cover is characterized by at least one of the immediately following features a. to e.: a. The cover is a cover assembly which, in addition to the metal disk, comprises a pole cap which is in electrical contact with the metal disk. b. The pole cap sits directly on the metal disk. c. The pole cap and the metal disk enclose a gap. d. The metal disk comprises a connecting region in which the connection to the connecting region of the distance compensation region of the contact sheet part or the distance compensation sheet part is realized. e. The pole cap comprises at least one opening through which the connecting region of the metal disk is accessible from outside the housing, in particular by means of a laser.

[0032] Particularly preferably, the immediately above features a. to e. are implemented in combination. In further preferred embodiments, at least features a. and c. - e. are implemented in combination.

[0033] When the cover is designed as a cover assembly, the opening in the pole cap ensures access to the connection area from the outside. This allows for welding using a laser.

[0034] If the aforementioned bonding or soldering is to be used instead of welding, a correspondingly positioned opening is not absolutely necessary.

[0035] In embodiments of the energy storage element according to the invention in which the contact sheet part assumes the function of distance compensation between the cover and the electrode-separator assembly, the energy storage element according to the invention is preferably characterized by at least one of the immediately following features a. to c. a. The contact sheet part comprises a contacting region, in particular a disk-shaped contacting region, to which the longitudinal edge of the anode current collector or the longitudinal edge of the is connected, in particular welded. b. The contacting region encloses the distance compensation region. c. The distance compensation region extends from the plane of the contacting region up to the metal disk.

[0036] Preferably, the immediately preceding features a. and b. are implemented in combination. Particularly preferably, the immediately preceding features a. to c. are implemented in combination.

[0037] In preferred embodiments, the contact sheet part thus comprises a contacting region and a distance compensation region extending from the plane of the contacting region to the metal disc, wherein the distance compensation region comprises a connection region in which the contact sheet part is connected to the inside of the metal disc. The connection region is thus preferably axially spaced from the plane of the contacting region. Furthermore, the contact sheet part thus preferably comprises two regions (the contacting region and the connection region) in different planes.

[0038] The contacting region of the contact sheet part can be designed as an annular disk. In other embodiments, the contacting region can have individual contact segments that are arranged around the distance compensation region and / or that are connected to one another via the distance compensation region. For example, the connecting region of the contact sheet part and the contacting region can be connected to one another via webs. The contact segments can also be ring segments, for example. As will be described below, in preferred embodiments the distance compensation region can be designed as a spring that presses downwards against the electrode-separator assembly and upwards against the cover. In preferred embodiments, the connecting region and the contacting region can be resiliently connected to one another, for example via the said webs.When clamped, the distance compensation area can be axially compressed, reducing the distance between the connection area and the contact area of ​​the contact sheet. In this case, the webs can be subjected to compressive stress.

[0039] In embodiments of the energy storage element according to the invention in which the distance compensation sheet part assumes the function of distance compensation between the cover and the electrode-separator assembly, the energy storage element according to the invention is preferably characterized by at least one of the immediately following features a. to c. a. The distance compensation sheet part comprises a contacting region, in particular an annular disk-shaped contacting region, which is connected to the contact sheet part in particular by said welding. b. The contacting region is arranged around the distance compensation region; in preferred embodiments, it encloses the distance compensation region. c. The distance compensation region extends from the plane of the contacting region up to the metal disk.

[0040] Preferably, the immediately preceding features a. and b. are implemented in combination. Particularly preferably, the immediately preceding features a. to c. are implemented in combination.

[0041] In preferred embodiments, the spacer compensating sheet metal part thus comprises a contacting region and a spacer compensating region extending from the plane of the contacting region to the metal disc, wherein the spacer compensating region comprises a connecting region in which the spacer compensating sheet metal part is connected to the inside of the metal disc. The connecting region is thus preferably axially spaced from the plane of the contacting region. Furthermore, the spacer compensating sheet metal part thus preferably comprises two regions (the contacting region and the connecting region) in different planes.

[0042] In addition to a ring-disk shape, the contacting area of ​​the spacer plate part can also have other configurations. For example, it can be ring-shaped and have a polygonal outer circumference, for example, an outer edge with six or eight corners. In other embodiments, the contacting area—as in the case of the contact plate part—can have individual contact segments that are arranged around the spacer plate area and / or that are connected to one another via the spacer plate area.

[0043] Here, too, the connecting area of ​​the spacer plate part and the contacting area can be connected to each other via webs.

[0044] In preferred embodiments, the connecting region and the contacting region can be resiliently connected to one another, for example via the aforementioned webs. In the tensioned state, the distance compensation sheet part can be axially compressed, so that the distance between the connecting region and the contacting region is reduced. In this case, the aforementioned webs can be subject to compressive stress. At this point, it should not go unmentioned that, in principle, the metal disc of the cover can also assume the task of distance compensation between the cover and the contact sheet part. For this purpose, the metal disc must comprise a distance compensation region which is connected to the contact sheet part in a connection region by welding or gluing.This distance compensation region then preferably extends in the axial direction to a contact plate part that rests on the first longitudinal edge of the anode current collector and covers the first terminal end face, or that rests on the first longitudinal edge of the cathode current collector and covers the second terminal end face and is connected, for example, welded, to the respective longitudinal edge. In preferred embodiments, the contact plate part can, for example, be flat or substantially flat.

[0045] Preferably, several safety functions are integrated into the cover of the energy storage element according to the invention: a. The metal disc of the cover is preferably designed as a PRV (pressure relief valve) and includes an elongated weakening groove for this purpose. b. In the connection area, the metal disc is characterized by a thinner material thickness than in the area surrounding the connection area.

[0046] Particularly preferably, the immediately above features a. and b. are implemented in combination. However, they can also be implemented independently of one another.

[0047] The immediately preceding feature b. is relevant in connection with a CID function of the lid, which will be explained below with reference to the drawings of the invention.

[0048] In any case, it should be noted that the energy storage element according to the invention is preferably an energy storage element that has both a PRV and a CID functionality.

[0049] With regard to the mechanical stability of the energy storage element according to the invention as well as the aforementioned safety functions, the following preferred features are also important: a. The housing comprises a seal made of a plastic material, which encloses the edge of the cover and is arranged between the cover and the housing cup. b. The energy storage element comprises a support ring made of a plastic material, which is arranged, in particular clamped, between the metal disc and the spacer plate part or between the metal disc and the contact plate part. c. The support ring rests on the contact area of ​​the contact plate part or the contact area of ​​the spacer plate part. d. The support ring is part of the seal.

[0050] Particularly preferably, the immediately above features a. to c., and in some particularly preferred embodiments also features a. to d., are implemented in combination.

[0051] In particularly preferred embodiments, the energy storage element is further characterized by the following features a. and b.: a. The housing cup comprises, in axial sequence, a base, a central section and a closure section, wherein the central section is cylindrical and, in the central section, the winding jacket of the electrode-separator assembly designed as a winding is in contact with the inside of the housing cup, and, in the closure section, the annular seal is in press contact with the edge of the cover and the inside of the housing cup, and b. In the closure section, the housing cup has an opening edge which defines the circular opening and is bent radially inwards over the edge of the cover enclosed by the seal, and which positively fixes the cover, including the seal, in the circular opening of the housing cup.

[0052] The electrode-separator assembly is preferably in direct contact with the inside of the housing cup. It is particularly preferably located directly against the inside of the housing cup. In some embodiments, however, it may be provided to electrically insulate the inside, for example, by means of a film. In this case, the electrode-separator assembly is in contact with the inner wall via the film.

[0053] The base of the housing cup is preferably circular. The housing cup is usually formed by deep drawing. However, it is also possible to form the cup by welding a base into a tubular half-section. The energy storage element according to the invention is preferably designed as a cylindrical round cell. Its height is preferably in the range of 50 mm to 150 mm. Its diameter is preferably in the range of 15 mm to 60 mm. Cylindrical round cells with these form factors are suitable, for example, for supplying power to electric drives in motor vehicles.

[0054] Embodiment as a lithium-ion energy storage element

[0055] In a particularly preferred embodiment of the invention, the energy storage element according to the invention is based on lithium-ion technology.

[0056] Basically, all electrode materials known for secondary lithium ion cells can be used for the electrodes of the energy storage element.

[0057] Carbon-based particles such as graphitic carbon or non-graphitic carbon materials capable of intercalating lithium, preferably also in particle form, can be used as active materials in the negative electrodes. Alternatively or additionally, lithium titanate (Li^3C) or a derivative thereof can also be contained in the negative electrode, preferably also in particle form. Furthermore, the negative electrode can contain as active material at least one material from the group consisting of silicon, aluminum, tin, antimony, or a compound or alloy of these materials that can reversibly intercalate and release lithium, for example silicon oxide (in particular SiO xwith 0 < x < 2), optionally in combination with carbon-based active materials. Tin, aluminum, antimony, and silicon are capable of forming intermetallic phases with lithium. The lithium absorption capacity, particularly in the case of silicon, exceeds that of graphite or comparable materials by several times. Mixtures of silicon- and carbon-based storage materials are often used. Thin anodes made of metallic lithium are also suitable.

[0058] For the positive electrodes, suitable active materials include lithium metal oxide compounds and lithium metal phosphate compounds such as LiCoO2 and LiFePO4. Lithium nickel manganese cobalt oxide (NMC) with the molecular formula LiNi is also particularly suitable. x Mn yCozO2 (where x + y + z is typically 1), lithium manganese spinel (LMO) with the molecular formula LiMn2O4, or lithium nickel cobalt aluminum oxide (NCA) with the molecular formula LiNi x Co y Al z O2 (where x + y + z is typically 1). Derivatives thereof, for example, lithium nickel manganese cobalt aluminum oxide (NMCA) with the molecular formula Lii.ii(Ni.4oMno.39Coo.i6Alo.o5)o.89O2 or Lii +xM-0 compounds and / or mixtures of the materials mentioned can be used. The cathodic active materials are also preferably used in particulate form. In addition, the electrodes of an energy storage element preferably contain an electrode binder and / or an additive to improve electrical conductivity. The active materials are preferably embedded in a matrix made of the electrode binder, with adjacent particles in the matrix preferably being in direct contact with one another. Conductive agents serve to increase the electrical conductivity of the electrodes. Common electrode binders are based, for example, on polyvinylidene fluoride (PVDF), (Li-)polyacrylate, styrene-butadiene rubber, or carboxymethyl cellulose, or mixtures of different binders. Common conductive agents are carbon black, fine graphite, carbon fibers, carbon nanotubes, and metal powder.

[0059] The energy storage element preferably comprises an electrolyte, in the case of a lithium-ion cell, in particular an electrolyte based on at least one lithium salt, such as lithium hexafluorophosphate (LiPFs), dissolved in an organic solvent (e.g., in a mixture of organic carbonates or a cyclic ether such as THF or a nitrile). Other usable lithium salts include, for example, lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(oxalato)borate (LiBOB).

[0060] The nominal capacity of a lithium-ion-based energy storage element designed as a cylindrical round cell is preferably up to 15,000 mAh. With a form factor of 21 x 70, the round cell in one embodiment as a lithium-ion cell preferably has a nominal capacity in the range of 1,500 mAh to 7,000 mAh, particularly preferably in the range of 3,000 to 5,500 mAh. With a form factor of 18 x 65, the round cell in one embodiment as a lithium-ion cell preferably has a nominal capacity in the range of 1,000 mAh to 5,000 mAh, particularly preferably in the range of 2,000 to 4,000 mAh.

[0061] In the European Union, manufacturer specifications regarding the nominal capacities of secondary batteries are strictly regulated. For example, specifications regarding the nominal capacity of secondary nickel-cadmium batteries must be based on measurements according to the standards IEC / EN 61951-1 and IEC / EN 60622; specifications regarding the nominal capacity of secondary nickel-metal hydride batteries must be based on measurements according to the standard IEC / EN 61951-2; specifications regarding the nominal capacity of secondary lithium batteries must be based on measurements according to the standard IEC / EN 61960; and specifications regarding the nominal capacity of secondary lead-acid batteries must be based on measurements according to the standard IEC / EN 61056-1. Any specifications regarding nominal capacities in this application are preferably also based on these standards.

[0062] Sodium-ion-based embodiment. In further embodiments, the energy storage element can also be a sodium-ion cell, a potassium-ion cell, a calcium-ion cell, a magnesium-ion cell, or an aluminum-ion cell. Among these variants, energy storage elements with sodium-ion cell chemistry are particularly preferred.

[0063] Preferably, the energy storage element based on sodium ions comprises an electrolyte comprising at least one of the following solvents and at least one of the following conductive salts:

[0064] Suitable solvents include organic carbonates, ethers, nitriles, and mixtures thereof. Preferred examples are:

[0065] Carbonate: Propylencarbonat (PC), Ethylencarbonat-Propylencarbonat (EC-PC), Propy-Ien- carbonat-Dimethylcarbonat-Ethylmethylcarbonat (PC-DMC-EMC), Ethylencarbonat-Diet- hylcarbonat (EC-DEC), Ethylencarbonat-Dimethylcarbonat (EC-DMC), Ethylencarbonat- Ethylmethylcarbonat (EC-EMC), Ethylencarbonat-Dimethylcarbonat-Ethylmethylcarbonat (EC-DMC-EMC), Ethylencarbonat-Dimethylcarbonat-Diethylcarbonat (EC-DMC-DEC)

[0066] Ether: Tetrahydrofuran (THE), 2-Methyltetrahydrofuran, Dimethylether (OME), 1,4-dioxane (DX), 1,3-dioxolane (DOL), Diethylenglykoldimethylether (DEGDME), Tetraethyl-englykol- dimethylether (TEGDME)

[0067] Nitrile: Acetonitril (ACN), Adiponitril (AON), y-Butyrolactone (GBL)

[0068] Weiterhin kommen auch Trimethylphosphat (TMP) und Tris(2,2,2-trifluoroethyl)phosphat (TFP) in Frage.

[0069] Bevorzugte Leitsalze sind:

[0070] NaPF6, sodium difluoro(oxalato)borate (NaBOB), NaBF4, sodium bis(fluorosulfonyl)imide (NaFSI), sodium 2-trifluoromethyl-4,5-dicyanoimidazole (NaTDI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), NaAsF6, NaBF4, NaCIO4, NaB(C2O4)2, NaP(C6H4O2)3; NaCF3SO3, sodium triflate (NaTf) and Et4NBF4.

[0071] In preferred embodiments, additives can be added to the electrolyte. Examples of preferred additives, particularly for stabilization, are the following:

[0072] Fluoroethylene carbonate (FEC), transdifluoroethylene carbonate (DFEC), ethylene sulfite (ES), vinylene carbonate (VC), bis(2,2,2-trifluoroethyl)ether (BTFE), sodium 2-trifluoromethyl-4,5-dicyanoimidazole (NaTDI), sodium bis(fluorosulfonyl)imide (NaFSI), aluminum chloride (AICI3), ethylene sulfate (DTD), sodium difluorophosphate (NaPO2F2), sodium difluoro(oxalato)borate (NaODFB), sodium difluorobisoxalatophosphate (NaDFOP) and tris(trimethylsilyl)borate (TMSB).

[0073] The negative electrode material of an energy storage element based on sodium ions is preferably at least one of the following materials:

[0074] Carbon, especially hard carbon (pure or with nitrogen and / or phosphorus doping) or soft carbon or graphene-based materials (with N-doping); carbon nanotubes, graphite

[0075] Phosphorus or sulfur (conversion anode)

[0076] Polyanions: Na2Ti3O7, NasTi^PC, TiP2O7, TiNb2O7, Na-TRPC, Na-V-(PO4)3

[0077] Prussian Blue: Low-Na variant (for systems with aqueous electrolyte)

[0078] Transition metal oxides: V2O5, MnO2, TiO2, Nb2O5, Fe2O3, Na2Ti3O7, NaCrTiC, Na4Ti50i2

[0079] MXenes with M= Ti, V, Cr, Mo or Nb and A = Al, Si, and Ga and X= C and / or N, e.g. Ti3C2

[0080] Organic: e.g. Na terephthalates (Na2CsH2O4)

[0081] Alternatively, a Na metal anode can also be used on the anode side.

[0082] The positive electrode material of a sodium ion-based energy storage element is, for example, at least one of the following materials:

[0083] Polyanions: NaFePO4(triphylite type), Na2Fe(P2O7), Na4Fe3(PO4)2(P2O7), Na2FePO4F, Na / Na2[Fei / 2 Mini / 2 ]PO4F, Na3V2(PO4)2F3, Na3V2(PO4)3, Na4(CoMnNi)3(PO4)2P2O7, NaCoPO4, Na2CoPO4F

[0084] Silicates: Na2MnSiO4, Na2FeSiO4

[0085] Layered oxides: NaCoO2, NaFeO2, NaNiO2, NaCrO2, NaVO2, NaTiO2, Na(FeCo)O2, Na(Ni-FeCo)3O2, Na(NiFeMn)O2, and Na(NiFeCoMn)O2, Na(NiMnCo)O2

[0086] In addition, the electrodes of an energy storage element according to the invention preferably contain an electrode binder and / or an additive to improve electrical conductivity. The active materials are preferably embedded in a matrix made of the electrode binder, wherein the active materials are preferably used in particulate form and adjacent particles in the matrix are preferably in direct contact with one another. Conductive agents serve to increase the electrical conductivity of the electrodes. Common electrode binders are based, for example, on polyvinylidene fluoride (PVDF), (Na) polyacrylate, styrene-butadiene rubber, (Na) alginate, or carboxymethyl cellulose, or mixtures of different binders. Common conductive agents are carbon black, fine graphite, carbon fibers, carbon nanotubes, and metal powder.

[0087] In an energy storage element based on sodium-ion technology, both the anode and cathode current collectors are particularly preferably made of aluminum or an aluminum alloy. The housing and contact plates, as well as any additional current conductors within the housing, can also be made of aluminum or the aluminum alloy. of the housing

[0088] The energy storage element according to the invention is particularly preferably characterized by at least one of the following features a. to c.: a. The central section and the closure section are separated by an indentation that runs annularly around the outside of the housing cup. b. The housing cup has an identical maximum outer diameter in the central section and the closure section. c. In the region of the indentation, the outer diameter of the housing cup is reduced, preferably by 4 to 20 times the wall thickness of the housing cup in this region.

[0089] It is preferred that at least the immediately above features a. and b. are implemented in combination. Particularly preferably, all three immediately above features a. to c. are implemented in combination.

[0090] The annular seal is preferably compressed in the closure portion. It is preferably pressed radially against the circular edge of the lid.

[0091] Contact sheet parts and spacers

[0092] Contact sheet parts suitable for the invention are preferably characterized by the following features a. to f.: a. The contact sheet part comprises a contacting region, in particular a disk-shaped contacting region, in which the connection to the longitudinal edge of the anode current collector or the longitudinal edge of the cathode current collector is formed. b. The contact sheet part comprises a distance compensation region which rises out of the plane of the contacting region. c. The contacting region is disk-shaped and preferably extends substantially in one plane. d. The contacting region encloses the distance compensation region. e. The distance compensation region comprises a central connection region with an underside pointing in the direction of the plane of the contacting region and an upper side pointing away from the plane of the contacting region. f. The upper side is flat.

[0093] Particularly preferably, the contacting area surrounds the distance compensation area in a ring shape. For example, it can be designed in the shape of an annular disk.

[0094] Spacer compensation sheet parts suitable for the invention are preferably characterized by the following features a. to f.: a. The spacer compensation sheet part comprises a contacting region, in particular an annular disk-shaped contacting region, in which the connection to the longitudinal edge of the anode current collector or the longitudinal edge of the cathode current collector is formed. b. The spacer compensation sheet part comprises a spacer compensation region which protrudes from the plane of the contacting region. c. The contacting region is disk-shaped and preferably extends substantially in one plane. d. The contacting region encloses the spacer compensation region. e. The spacer compensation region comprises a central connection region with an underside pointing in the direction of the plane of the contacting region and an upper side pointing away from the plane of the contacting region. f. The upper side is flat.Particularly preferably, the contacting area surrounds the distance compensation area in a ring shape. In particular, it can be designed in the shape of an annular disk.

[0095] A cover assembly according to the invention is characterized by the following features a. to e.: a. The cover assembly comprises a metal disk and a pole cap, which are in electrical and direct mechanical contact with one another. b. The pole cap sits directly on the metal disk. c. The pole cap and the metal disk enclose a gap. d. The pole cap comprises at least one opening through which the connection area for a laser is accessible from outside the housing, in particular is accessible for a laser from outside the housing. e. The cover assembly comprises a seal that is fitted onto its edge. rmen of the contact sheet part and the Di

[0096] In principle, the contact plate part can be electrically connected to the anode current collector or the cathode current collector.

[0097] In a particularly preferred embodiment of the invention, a contact sheet part electrically connected to the anode current collector is characterized by at least one of the following features a. and b.: a. The contact sheet part is made of nickel or copper or titanium or a nickel or copper or titanium alloy or stainless steel, for example of type 1.4303 or 1.4404 or of type SUS304, or of nickel-plated copper. b. The contact sheet part is made of the same material as the anode current collector.

[0098] In another particularly preferred embodiment of the invention, a contact sheet part electrically connected to the cathode current collector is characterized by at least one of the following features a. and b.: a. The contact sheet part is made of aluminum or an aluminum alloy. b. The contact sheet part is made of the same material as the anode current collector.

[0099] The distance compensation plate part is preferably made of the same material as the contact plate part to which it is welded.

[0100] Particularly preferably, the contact sheet part connected to the anode current collector and / or the contact sheet part electrically connected to the cathode current collector are characterized by at least one of the immediately following features a. and b.: a. The contact sheet part has a preferably uniform thickness in the range from 50 pm to 600 pm, preferably in the range from 150 pm to 350 pm. b. The contact sheet part is dimensioned such that it covers at least 40%, preferably at least 70%, particularly preferably at least 80% of the first terminal or the second terminal end face.

[0101] It is particularly preferred that the immediately above features a. and b. are implemented in combination with one another.

[0102] The spacer plate part is preferably made of a sheet with a thickness in the range of 50 pm to 1 mm.

[0103] Covering the front side as extensively as possible is important for the thermal management of the energy storage element according to the invention. The larger the cover, the easier it is to contact the longest possible sections of the first longitudinal edge of the respective current collector. Heat generated in the electrode-separator assembly can thus be effectively dissipated via the contact sheet.

[0104] In some embodiments, it has proven advantageous to subject the longitudinal edge of the current collector to a pretreatment before the contact sheet part is attached.

[0105] The longitudinal edge of the current collector may also have undergone directional deformation through pretreatment. For example, it may be bent in a defined direction. Furthermore, the longitudinal edge of the current collector may also be deformed in a non-directional manner, for example, as a result of pressure contact with the contact sheet.

[0106] Preferred design of current collectors and separators The anode current collector, the cathode current collector and the separator or separators of the cell according to the invention preferably have the following dimensions:

[0107] A length in the range of 0.5 m to 25 m

[0108] A width in the range 40 mm to 145 mm

[0109] In the electrode-separator assembly formed as a coil, the strip-shaped anode, the strip-shaped cathode, and the strip-shaped separator(s) are preferably wound spirally. To produce the electrode-separator assembly, the strip-shaped electrodes and the strip-shaped separator(s) are generally fed to a winding device and wound spirally therein, preferably around a winding axis. Gluing the electrodes and separators or contacting them at elevated temperatures is usually not necessary. In some embodiments, the electrodes and the separator(s) are wound onto a cylindrical or hollow-cylindrical winding core, which sits on a winding mandrel and remains in the coil after winding.

[0110] The winding sleeve can be formed, for example, by a plastic film or an adhesive tape. It is also possible for the winding sleeve to be formed by one or more separator windings.

[0111] The current collectors of the energy storage element according to the invention serve to electrically contact electrochemically active components contained in the respective electrode material over as large an area as possible. The current collectors are preferably made of a metal or at least have a metallized surface.

[0112] In the case of an energy storage element according to the invention designed as a lithium-ion cell, suitable metals for the anode current collector include, for example, copper or nickel or other electrically conductive materials, in particular copper and nickel alloys or nickel-coated metals. 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. Suitable nickel alloys include, in particular, alloys of the types NiFe, NiCu, CuNi, NiCr, and NiCrFe. Suitable nickel alloys include, in particular, alloys of the types NiFe, NiCu, CuNi, NiCr, and NiCrFe. Stainless steel is also generally suitable, for example, type 1.4303 or 1.4404 or type SUS304.

[0113] In the case of an energy storage element according to the invention designed as a lithium-ion cell, aluminum or other electrically conductive materials, including aluminum alloys, are particularly suitable as the metal for the cathode current collector.

[0114] Suitable aluminum alloys for the cathode current collector include aluminum alloys of type 1235, 1050, 1060, 1070, 3003, 5052, Mg3, Mg212 (3000 series), and GM55. Also suitable are AlSi, AlCuTi, AlMgSi, AlSiMg, AlSiCu, AlCuTiMg, and AlMg. The aluminum content of these alloys is preferably above 99.5%.

[0115] Preferably, the anode current collector and / or the cathode current collector are each a strip-shaped metal foil with a thickness in the range of 4 pm to 30 pm.

[0116] In addition to foils, other strip-shaped substrates such as metallic or metallized nonwovens or open-pored metallic foams or expanded metals can also be used as current collectors.

[0117] The current collectors are preferably loaded on both sides with the respective electrode material.

[0118] It is preferred that the longitudinal edges of the separator(s) form the end faces of the electrode-separator assembly formed as a coil.

[0119] Possible designs of the seal

[0120] It is preferred that the energy storage element according to the invention is characterized by at least one of the immediately following features a. and b.: a. The seal consists of a plastic material having a melting point of > 200°C, preferably > 300°C, particularly preferably a melting point of > 300°C and < 350°C. b. The plastic material is a polyetheretherketone (PEEK), a polyimide (PI), a polyphenylene sulfide (PPS), a polytetrafluoroethylene (PTFE), or a polybutylene terephthalate (PBT).

[0121] It is preferred that the immediately above features a. and b. are implemented in combination.

[0122] Method according to the invention. The method according to the invention can be used to produce an energy storage element as described above and is characterized by the following steps: a. Providing a metallic housing can with a circular opening at its end. b. Providing an electrode-separator assembly with the anode / separator / cathode sequence, which assembly has a first end face and a second end face. c. Applying a contact sheet part to one of the end faces. d. Optionally, welding a spacer compensating sheet part to the contact sheet or fixing a spacer compensating sheet part to the contact sheet part by forming a material-to-material or form-fitting connection, in particular an adhesive connection, a soldered connection, or a riveted connection. e. Inserting the electrode-separator assembly into the housing can. f.Closing the circular opening of the housing cup using a cover. g. Establishing a connection, in particular a welded connection, between the cover and the contact plate part or between the cover and the spacer plate part.

[0123] All components used in the process have already been described. Reference is hereby made to the relevant sections.

[0124] Step c. preferably takes place before step e. However, it is generally possible to apply the contact sheet part to one of the end faces (the one facing the opening) of the housing cup even after the electrode-separator assembly has been inserted into the housing cup. In both cases, it is preferable to form the connection between the longitudinal edges of the current collector emerging from this end face and the contact sheet part after application. For example, laser welding can be used to create a material-to-material bond.

[0125] In many cases, one of the end faces of the electrode-separator assembly sits directly on the bottom of the housing cup after the electrode separator has been inserted. It is then generally necessary to contact the current collector edge emerging from this end face with the housing base. This can be done, for example, by welding using a laser through the housing base. In other possible embodiments, a suitable contact plate part is applied to this end face before step e., so that after insertion only this contact plate part needs to be contacted with the housing cup or its base, for example via a welded connection. The welded connection between the contact plate part and the base can be created, for example, by resistance welding.For this purpose, a welding electrode can be guided through an axial cavity in the coil, a second welding electrode can be pressed to the ground from the outside.

[0126] Step d. is required in cases where the contact sheet itself does not include a distance compensation area. Step d. can also be performed before or after step e., i.e., the insertion of the electrode-separator assembly into the housing cup.

[0127] Conventional closure methods can be used to close the circular opening of the housing cup using the lid. Crimping is particularly preferred. During this process, the edge of the housing cup is bent radially inward, while simultaneously compressing the seal in the manner described above.

[0128] The electrode-separator assembly can be impregnated with a suitable electrolyte before or after the housing is sealed. In the second variant, the electrolyte must be added through a suitable hole in the housing, which is then sealed.

[0129] Establishing the connection, preferably a material connection, in particular a welded connection, between the cover and the contact plate part or between the cover and the distance compensation plate part after the housing has been closed is one of the core aspects of the present invention. This step makes it possible to dispense with the long tab mentioned above.

[0130] The welded connection between the cover and the contact plate part or between the cover and the spacer plate part can be achieved, in particular, by laser welding. For this purpose, a laser beam can be directed through the above-described at least one opening in the pole cap onto the also previously described connecting area of ​​the metal disc of the cover, on the inside of which the central connecting area of ​​the spacer plate part of the spacer plate part or the contact plate part rests.

[0131] In some embodiments, it is particularly preferred to guide two or more welding electrodes through the at least one opening, which are pressed onto the connecting area of ​​the metal disc of the cover at a distance from one another. When an electrical voltage is applied between the welding electrodes, the current flowing between the electrodes can flow through the metal disc and cause a weld on its inner side to the spacer plate part or the contact plate part.

[0132] If the bonding described above or the aforementioned soldering is used instead of welding, step g. of the method according to the invention is omitted. Alternatively, in these cases, it is preferred that an electrically conductive adhesive or solder is applied to the connecting area of ​​the contact sheet part or the spacer plate part. In a subsequent step, the cover or the connecting area of ​​the metal disc of the cover is pressed onto the connecting area of ​​the contact sheet part or the spacer plate part, or the adhesive or liquefied solder applied thereto. A reliable electrical connection can also be established in this way.

[0133] The cell closure is preferably followed by a calibration process in which the height of the energy storage element is calibrated. Both during closure and calibration, significant axial forces can act on the housing and the components within it. These can be compensated for by the support ring described above and the spacer plate or contact plate.

[0134] BRIEF DESCRIPTION OF THE DRAWINGS

[0135] Further features and advantages of the invention will become apparent from the claims and the following description of preferred embodiments of the invention in conjunction with the drawings. The features presented therein may be implemented individually or in combination with other features.

[0136] The drawings show schematically

[0137] Fig. 1 shows a section of a cross-sectional view of a first embodiment of an energy storage element according to the invention with a cover assembly according to the invention and a spacer compensating sheet part according to the invention;

[0138] Fig. 2 shows a section of a cross-sectional view of a second embodiment of an energy storage element according to the invention;

[0139] Fig. 3 shows a section of a cross-sectional view of a third embodiment of an energy storage element according to the invention; Fig. 4 shows a partially sectioned illustration of the first embodiment of the energy storage element according to the invention;

[0140] Fig. 5 is a representation of a preferred embodiment of a cover assembly according to the invention;

[0141] Fig. 6 is a representation of a preferred embodiment of a spacer compensating sheet part suitable for an energy storage element according to the invention;

[0142] Fig. 7 is a representation of a preferred embodiment of a contact sheet part suitable for an energy storage element according to the invention;

[0143] Fig. 8 shows an electrode-separator assembly which can be a component of an energy storage element according to the invention, as well as its components;

[0144] Fig. 9 is a view (cross-sectional representation) of the bottom region of an energy storage element according to the invention;

[0145] Fig. 10 is a cross-sectional view of a fourth embodiment of an energy storage element according to the invention.

[0146] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0147] The energy storage element 100 shown in Fig. 1 comprises the electrode-separator assembly 104, which is in the form of a cylindrical coil with two terminal end faces and a coil casing located between them. The first longitudinal edge 106a of the anode current collector 106 extends from the terminal end face 104a. This is not loaded with electrode material and is welded to the contact sheet part 112, which rests on the longitudinal edge 106a and covers the first terminal end face 104a.

[0148] Furthermore, the energy storage element 100 comprises a sealed, airtight and liquid-tight housing, which comprises the metallic housing cup 101 with a circular opening at its end and the cover assembly 102 with a circular rim 102a that closes the circular opening. The cover assembly 102 is designed according to the invention. It comprises the metal disc 113, the underside 113b of which defines the interior space 140 of the housing, and the pole cap 117, which sits directly on the metal disc 113 and is in electrical contact with it, as well as enclosing a gap therewith.

[0149] Welded onto the contact plate part 112 is the distance compensation plate part 177, which comprises a distance compensation region 177a, which is connected in a connection region 177b by welding to the inner side 113b of the metal disk 113, which rests directly on the connection region 177b. The distance compensation plate part 177 is designed according to the invention. The connection region 177b is delimited by the annular groove 178. Furthermore, the distance compensation plate part 177 comprises the annular disk-shaped contacting region 177c. This is connected to the contact plate part 112 by welding and encloses the distance compensation region 177a, which extends from the plane of the contacting region 177c to the metal disk 113. The metal disk 113 comprises the connection region 113a in its center, in which the welding to the connection region 177b is realized.It is designed as a PRV (pressure relief valve) and for this purpose includes the circular, elongated weakening groove 199.

[0150] The pole cap 117 comprises several openings, including the hole 117a, through which the connection area 113a for a laser is accessible from outside the housing.

[0151] The housing further includes the plastic seal 103, which surrounds the edge 102a of the cover assembly 102 and electrically insulates the metallic components of the cover assembly 102 from the housing cup 101. At the same time, it helps seal the housing.

[0152] The energy storage element 100 further comprises a support ring 189, which is clamped between the metal disc 113 and the spacer plate part 177. The support ring 189 rests on the contact area 177c of the spacer plate part 177 and presses against the metal disc 113 from below. In this case, the support ring 189 is part of the seal 103.

[0153] The illustrated embodiment of the energy storage cell 100 according to the invention has various advantages:

[0154] The cover assembly 102 according to the invention consists of only three parts, namely (from outside to inside) the pole cap 117, the metal disc 113, and the seal 103. Conventional cover assemblies with a comparable function generally comprise at least four parts. In contrast, the construction of the cover assembly 102 is simplified.

[0155] - The spacer plate part 177 replaces the "tabs" mentioned above.

[0156] The resulting simplified structure allows a welded connection between the spacer plate 177 and the metal disc 113 to be created only after the housing has been closed. All that is required is the hole 117a in the pole cap 117, as shown in the drawing. Welding can be performed externally using a laser. The energy storage cell 100 is characterized by two safety functions: a PRV (pressure relief valve) and the aforementioned CID. The PRV is implemented by the groove 199. If the pressure inside the housing exceeds a predefined limit, the metal disc 113 tears open along the groove 199.

[0157] - The circular groove in the spacer area 177a ensures the CID function. When the pressure inside the housing increases, the metal disc 113 bulges outward. Due to the welded connection between the metal disc 113 and the spacer area 177a, the bulging diaphragm exerts a tensile force on the spacer area 177a. If this force is strong enough, the connecting area 177b is torn out of the spacer area 177a along the groove 178. This interrupts the direct contact and electrical connection between the metal disc 113 and the spacer area 177a, leaving a hole in the upper part of the spacer area 177a.

[0158] Another important aspect: There is a risk that the aforementioned tensile force could lift the entire spacer plate 177 along with the metal disc 113, rendering the CID inoperable. To prevent such a situation, the seal can enclose the support ring 189. If the metal disc 113 bulges outward, the support ring holds the spacer plate 177 in place, ensuring the CID's function.

[0159] The energy storage element 100 shown in Fig. 2 differs from that shown in Fig. 1 only in that the support ring 189 is not formed as part of the seal 102.

[0160] The energy storage element 100 shown in Fig. 3 differs from that shown in Fig. 1 in that the support ring 189 is not formed as part of the seal 102. Another difference is that the edge 177d of the contacting area 177c is bent upward by 90°.

[0161] Fig. 4 is a partially sectioned view of the embodiment of the energy storage element according to the invention shown in Fig. 1.

[0162] The cover assembly 102 shown in Fig. 5 comprises the pole cap 117, the metal disk 113, the annular seal 103, and the support ring 116. The metal disk 113 is in direct contact with the pole cap 117. The annular seal 103 is mounted on the circular edge of the cover assembly 102. The edge of the cover assembly is in turn formed by the edge of the metal disk 113, which is folded over in a U-shape around the edge of the pole cap 117. The pole cap 117 has a central hole 117a as an opening. The center of the metal disk 113 is located below this hole. In the center of the metal disk 113 is the connecting area 113a, which is characterized by a thinner material thickness compared to the surrounding areas.

[0163] The cover assembly is shown in an unassembled state.

[0164] Fig. 6 shows a distance compensation plate part 177 that can be used in the context of the present invention. This comprises the annular disk-shaped contacting area 177c, which can be connected to the contact plate part 112 by welding. The contacting area 177c encloses the distance compensation area 177a, which protrudes from the plane of the contacting area 177c. The distance compensation area 177a, in turn, comprises the circular connecting area 177b defined by the circular groove 178, which has a flat surface, as well as three webs 177g that connect the contacting area 177c to the connecting area 177b. Between the webs, three openings 177f are arranged, which are provided for the passage of electrolyte and for pressure equalization. The recesses 177e also serve the same purpose.

[0165] Fig. 7 shows a contact sheet part 112 that can be used within the scope of the present invention. This comprises the disk-shaped contacting region 112c, which is intended for welding to the longitudinal edge 106a of the anode current collector 106 or the longitudinal edge 109a of the cathode current collector 109. Preferably, the contacting region 112c extends substantially in one plane. The contacting region 112c encloses the distance compensation region 112d, which protrudes from the plane of the contacting region 112c. The distance compensation region 112d, in turn, comprises the circular connecting region 112e, which has a flat surface, as well as three webs 112f that connect the contacting region 112c to the connecting region 112e.

[0166] In the contact area 112c, there are three beads 166 arranged in a star shape. Welding to one of the longitudinal edges can occur in the area of ​​these beads 166.

[0167] Distance compensation is often necessary in energy storage elements, as shown in Figures 1 to 4, because individual components such as the electrode-separator assembly 104 cannot always be manufactured with exactly the same dimensions, for example with exactly the same height. Instead, process-related differences arise which must be compensated for. The contact sheet part 112 shown enables tolerance compensation in the axial direction within a cell while simultaneously contacting the electrode-separator assembly or the overhang of the longitudinal edge which emerges from the front of the assembly. In the embodiment shown, the distance compensation region 112d can act as a spring which presses downwards against the electrode-separator assembly and upwards against the cover. During the calibration mentioned, this spring effect in particular can have a compensating effect.

[0168] Fig. 8 illustrates the structure of an electrode-separator composite 104, which can be a component of an energy storage element according to the invention. The composite 104 comprises the strip-shaped anode 105 with the strip-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 copper or nickel. This comprises a strip-shaped main region loaded with a layer of negative electrode material 107, as well as a free edge strip 106b, which extends along its first longitudinal edge 106a and is not loaded with the electrode material 107. Furthermore, the composite 104 comprises the strip-shaped cathode 108 with the strip-shaped cathode current collector 109, which has a first longitudinal edge 109a and a second longitudinal edge parallel thereto. The cathode current collector 109 is an aluminum foil.It comprises a band-shaped main region loaded with a layer of positive electrode material 110, as well as a free edge strip 109b extending along its first longitudinal edge 109a and not loaded with the electrode material 110. Both electrodes are shown individually in the unwound state.

[0169] The anode 105 and the cathode 108 are arranged offset from one another within the electrode-separator assembly 104, so that the first longitudinal edge 106a of the anode current collector 106 extends from the first terminal end face 104a, and the first longitudinal edge 109a of the cathode current collector 109 extends from the second terminal end face 104b of the electrode-separator assembly 104. The offset arrangement is evident in the illustration at the bottom left. Also shown there are the two band-shaped separators 156 and 157, which separate the electrodes 105 and 108 from one another in the winding.

[0170] The illustration 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 one of Figures 1 to 4. The electrode edges 106a and 109a protruding from the end faces 104a and 104b are clearly visible. The wound sheath 104c is formed by a plastic film.

[0171] Fig. 9 shows the bottom region of a preferred embodiment of an energy storage element 100 according to the invention. The electrode-separator assembly 104 is arranged in the housing can 101. The contact sheet part 132 sits on the bottom 101a of the housing can. Its underside is preferably connected to the bottom 101a by welding. The welding can be effected through the bottom 101a using a laser. Alternatively, for example, at least one welding electrode can be guided through the axial cavity 150 in the center of the electrode-separator assembly 104. A counter electrode can also be pressed against the outside of the bottom 101a. The top side of the contact sheet part 132 is in direct contact with the longitudinal edge 109a of an anode current collector. The longitudinal edge 109a and the contact sheet part 132 are preferably also connected by welding.

[0172] The contact plate part 132 is shown separately. Like the contact plate part 112, it has beads to improve contact with the longitudinal edge 109a. The slot-shaped openings serve for degassing and better distribution of the electrolyte.

[0173] The embodiment of an energy storage element according to the invention shown in Fig. 10 differs from the energy storage elements shown in Figs. 1 to 4 in that the contact sheet part 112 comprises the distance compensation region 112d, which is connected to the inside of the metal disc 113 in the connection region 112e. The embodiment shown here therefore does not comprise a distance compensation sheet part welded onto a contact sheet part. The contact sheet part itself performs the function of the distance compensation sheet part. This has obvious advantages. Starting at the pole cap, which can serve as a contact pole for tapping an electrical voltage from the energy storage element, electrical contacting of the electrode-separator assembly is realized via just two metal parts, namely the metal disc 113 and the contact sheet part 112.

[0174] The contact plate part 112 sits with the contacting region 112c on the upper end face of the electrode-separator assembly 104, which is designed as a coil, and is connected to the current collectors emerging at this end face, ideally by welding. The contact plate part 112 can be designed identically or similarly to the contact plate part shown in Fig. 7. The contacting region 112c encloses the annular distance compensation region 112d, which rises dome-like from the plane of the contacting region 112c and extends to the metal disk 113 or the connecting region 113a of the metal disk 113. The distance compensation region 112d comprises the connecting region 112e there. The contact plate part thus preferably comprises two regions (the contacting region 112c and the connecting region 112e) in different planes that are axially spaced from one another.

[0175] The metal disc 113 and the contact plate part 112 are welded together in the connecting areas 112e and 113a. As in the case of the energy storage element, the grooves 199 and 178 ensure a PRV and a CID function. The latter is supported by the support ring 189. This sits on the contacting area 112c and is arranged between it and the edge area of ​​the metal disc 113. If the center of the metal disc 113 bulges upward as a result of pressure, the contacting area 112c is fixed by the support ring on the end face of the winding 104 and cannot be lifted. This ensures that the connecting area 112e can be blown out with sufficient pressure, interrupting the current flow.

[0176] It's worth noting that the cell shown has a housing cup 101, which is characterized by an increased thickness in the closure section. Below the transition 101e, the housing cup is thinner than above. This is because, depending on the closure technology, greater mechanical strength is required in the closure section than in the central section in certain cases. Housing material can be saved there.

[0177] It is also worth mentioning that it may be advantageous if at least the metal disc 113, but possibly also the contact sheet part 112, have a hole in their respective connecting areas through which pressure equalization can occur between the housing interior and the housing environment. This can be helpful when creating the welded connection between the connecting areas. The hole(s) can be closed after the welded connection has been created or during the welded connection.

Claims

PATENT CLAIMS 1. Energy storage element (100) with the following features: a. The energy storage element comprises an electrode-separator assembly (104) with the sequence anode (105) / separator (106) / cathode (108), b. the electrode-separator assembly (104) is in the form of a cylindrical coil with a first terminal end face (104a) and a second terminal end face (104b) and a coil jacket (104c) located therebetween, c. the anode (105) of the electrode-separator assembly (104) comprises an anode current collector (106) which has a first longitudinal edge (106a) and a second longitudinal edge parallel thereto and a main region which is loaded with a layer (107) of negative electrode material, and a free edge strip which extends along its first longitudinal edge (106a) and which is not loaded with the negative electrode material, i.e.the cathode (108) of the electrode-separator assembly (104) comprises a cathode current collector (109) having a first longitudinal edge (109a) and a second longitudinal edge parallel thereto and a main region loaded with a layer of positive electrode material (110), and a free edge strip extending along its first longitudinal edge (109a) and not loaded with the electrode material (110), e. the anode (105) and the cathode (108) are arranged within the electrode-separator assembly (104) such that the first longitudinal edge (106a) of the anode current collector (106) emerges from the first terminal end face (104a) and the first longitudinal edge (109a) of the cathode current collector (108) emerges from the second terminal end face (104b) of the electrode-separator assembly (104), f.the energy storage element comprises a contact sheet part (112) which sits on the first longitudinal edge (106a) of the anode current collector (106) and covers the first terminal end face (104a) or sits on the first longitudinal edge (109a) of the cathode current collector (109) and covers the second terminal end face (104b) and is connected thereto, g. the energy storage element comprises an airtight and liquid-tight housing which has a metallic housing cup (101) with a terminal. circular opening and a cover (102) with a circular edge (102a) which closes the circular opening, and which encloses an interior space in which the electrode-separator assembly (104) is arranged, h. the cover (102) comprises a metal disc (113) with a circular edge, wherein the metal disc (113) has an inner side which delimits the interior space, characterized in that i. either the contact sheet part (112) comprises a distance compensation region (112d) which is connected to the inner side of the metal disc (113) in a connecting region (112e), or a distance compensation sheet part (177) is welded onto the contact sheet part (112), wherein the distance compensation sheet part (177) comprises a distance compensation region (177a) which is connected to the inner side of the metal disc (113) in a connecting region (177b).

2. Energy storage element (100) according to claim 1, having at least one of the following additional features: a. The cover (102) is a cover assembly which, in addition to the metal disk (113), comprises a pole cap (117) which is in electrical contact with the metal disk (113). b. The pole cap (117) sits directly on the metal disk (113). c. The pole cap (117) and the metal disk (113) enclose a gap. d. The metal disk (113) comprises a connecting region (113a) in which the connection to the connecting region (112e) or the connecting region (117b) is realized. e. The pole cap (117) comprises at least one opening (117a) through which the connecting region (113a) is accessible from outside the housing, in particular for a laser from outside the housing.

3. Energy storage element (100) according to claim 1 or claim 2 with at least one of the following additional features: a. The contact plate part (112) comprises a contacting region (112c), in particular a disk-shaped contacting region, to which the longitudinal edge (106a) of the anode current collector (106) or the longitudinal edge (109a) of the cathode current collector (109) is welded or connected via an alternative material-to-material or form-fitting connection. b. The contacting region (112c) encloses the distance compensation region (112d), which extends from the plane of the contacting region (112c) to the metal disk (113).

4. Energy storage element (100) according to claim 1 or claim 2, with at least one of the following additional features: a. The distance compensation plate part (177) comprises a contacting region (177c), in particular an annular disk-shaped contacting region (177c), which is connected to the contact plate part (112) by welding or via an alternative material-to-material or form-fitting connection to the contact plate part (112). b. The contacting region (177c) encloses the distance compensation region (177a), which extends from the plane of the contacting region (177c) up to the metal disk (113).

5. Energy storage element (100) according to one of the preceding claims, with at least one of the following additional features: a. The metal disc (113) is designed as a PRV (pressure relief valve) and, for this purpose, comprises an elongated weakening groove (199). b. In the connecting region (113a), the metal disc (113) is characterized by a thinner material thickness than in the region surrounding the connecting region (113a).

6. Energy storage element (100) according to one of the preceding claims, with at least one of the following additional features: a. The housing comprises a seal (103) made of a plastic material, which seal surrounds the edge (102a) of the cover (102) and is arranged between the cover (102) and the housing cup (101). b. The energy storage element comprises a support ring (189) made of a plastic material, which is arranged, in particular clamped, between the metal disc (113) and the spacer plate part (177) or between the metal disc (113) and the contact plate part (112). c. The support ring (189) rests on the contacting area (112c) of the contact plate part (112) or the contacting area (177c) of the spacer plate part (177). d. The support ring (189) is part of the seal (103).

7. Energy storage element (100) according to at least one of the preceding claims with at least one of the following additional features: a. The housing cup (101) comprises, in axial sequence, a base (101a), a central section (101b) and a closure section (101c), wherein the central section (101b) is cylindrical and in the central section (101b) the winding jacket (104c) of the electrode-separator assembly (104) designed as a winding is in contact with the inside of the housing cup (101), and in the closure section (101c) the annular seal (103) is in press contact with the edge of the cover (102) and the inside of the housing cup (101), and b.the housing cup (101) has, in the closure section (101c), an opening edge (101d) which defines the circular opening and which is bent radially inward over the edge of the cover (102) enclosed by the seal (103) and which fixes the cover (102) including the seal (103) in a form-fitting manner in the circular opening of the housing cup (101).

8. Cover assembly (112) having the following features: a. The cover assembly comprises a metal disc (113) and a pole cap (117) which are in electrical and direct mechanical contact with each other. b. The polar cap (117) sits directly on the metal disc (113). c. The polar cap (117) and the metal disc (113) enclose a gap. d. The polar cap (117) comprises at least one opening (117a) through which the connection region (113a) is accessible from outside the housing, in particular for a laser. e. The cover assembly comprises a seal (103) mounted on its edge.

9. A method for producing an energy storage element (100) according to one of claims 1 to 7, comprising the following steps: a. Providing a metallic housing can (101) with a circular opening at its end. b. Providing an electrode-separator assembly (104) with the sequence anode (105) / separator (156) / cathode (108), which assembly has a first end face (104a) and a second end face (104b). c. Applying a contact sheet part (112) to one of the end faces. d. Optionally, welding a spacer compensating sheet part (177) onto the contact sheet part or fixing a spacer compensating sheet part (177) to the contact sheet part by forming an alternative material-to-material connection or a form-fitting connection. e. Inserting the electrode-separator assembly (104) into the housing cup (101). f. Closing the circular opening of the housing cup (101) using a cover (102). g.Producing a connection, in particular a welded connection, between the cover (102) and the contact sheet part (112) or between the cover (102) and the distance compensation sheet part (177).

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