Energy storage element and method for manufacturing such an energy storage element

Abstract

The present invention relates to an energy storage element including an electrode-separator assembly in a housing, which further includes a metal portion covering a first terminal end face of the electrode-separator assembly and welded to a free end strip of a current collector protruding from the end face. The metal portion further includes a protrusion extending away from the end face, the protrusion being inserted into or protruding through an aperture in the bottom of the housing, thereby allowing the protrusion to be mechanically contacted from outside the housing. The present invention also relates to a method for manufacturing such an energy storage element.

Description

[Technical Field]

[0001] The invention described below relates to an energy storage element and a method for manufacturing such an energy storage element. [Background technology]

[0002] Electrochemical energy storage elements can convert stored chemical energy into electrical energy through oxidation-reduction reactions. The simplest form of an electrochemical energy storage element is an electrochemical cell, which contains a positive electrode and a negative electrode separated from each other by a separator. During discharge, electrons are released at the negative electrode as a result of an oxidation process. This results in an electronic current that can be extracted by an external electricity consumer, and the electrochemical cell therefore functions as an energy supplier. At the same time, an ionic current corresponding to the electrode reactions is generated within the cell. This ionic current passes through the separator, which is made possible by an ion-conducting electrolyte.

[0003] If the discharge is reversible, i.e., the conversion of chemical energy to electrical energy during discharge can be reversed and the cell can be charged again, it is called a secondary cell. The common designation of the negative electrode as the anode in a secondary cell and the positive electrode as the cathode in a secondary cell refers to the discharge function of the electrochemical cell.

[0004] Secondary lithium-ion cells are currently used in many applications as energy storage elements, as they are capable of delivering large currents and feature relatively high energy densities. They are based on the use of lithium, which can be transported in the form of ions back and forth between the electrodes of the cell.

[0005] The negative and positive electrodes of lithium-ion cells are generally formed by so-called composite electrodes, which contain an electrochemically inactive component and an electrochemically active component.

[0006] In principle, any material capable of absorbing and releasing lithium ions can be used as the electrochemically active component (active material) of a secondary lithium-ion cell. For example, carbon-based particles, such as graphitic carbon, are used in the negative electrode. Active materials that can be used in the positive electrode include lithium cobalt oxide (LiCoO), lithium manganese oxide (LiMnO), lithium iron phosphate (LiFePO), or derivatives thereof. The electrochemically active material is generally contained in the electrode in particulate form.

[0007] As electrochemically inactive components, composite electrodes generally contain flat and / or strip-shaped current collectors, e.g., metal foils, that serve as carriers for the respective active materials. The negative electrode current collector (anode current collector) may be made of, for example, copper or nickel, and the positive electrode current collector (cathode current collector) may be made of, for example, aluminum. Furthermore, electrodes may contain electrode binders (e.g., polyvinylidene fluoride (PVDF) or other polymers, e.g., carboxymethyl cellulose), additives that improve conductivity, and other additives as electrochemically inactive components. The electrode binder ensures the mechanical stability of the electrode and, in many cases, also ensures adhesion of the active materials to the current collectors.

[0008] As an electrolyte, lithium-ion cells generally contain a solution of a lithium salt, such as lithium hexafluorophosphate (LiPF4), in an organic solvent (e.g., an ether and an ester of carbonic acid).

[0009] When lithium-ion cells are fabricated, composite electrodes are typically combined with one or more separators to form an electrode-separator assembly. The electrodes and separators are often, but not necessarily, joined together, optionally under pressure, by lamination or bonding. Basic cell function can then be established by impregnating the assembly with an electrolyte.

[0010] In many embodiments, the electrode-separator assembly is formed in the form of a wound body or processed into a wound body. In the first case, for example, the ribbon-type positive electrode and ribbon-type negative electrode and at least one ribbon-type separator are separately fed into a winding machine and spirally wound to obtain a wound body having a positive electrode (cathode) / separator / negative electrode (anode) arrangement. In the second case, the ribbon-type positive electrode and ribbon-type negative electrode and at least one ribbon-type separator are first combined to form the electrode-separator assembly, for example, by applying pressure as described above. In a further step, the assembly is then wound up.

[0011] For applications in the automotive sector, for e-bikes or other applications with high energy requirements such as tools, lithium-ion cells with the highest possible energy density are required that can also withstand high currents during charging and discharging.

[0012] Cells for the aforementioned applications are often shaped as cylindrical round cells, with a form factor of, for example, 21 x 70 (diameter x height in mm). This type of cell always includes an assembly in the form of a wound body. Modern lithium-ion cells in this form factor are already capable of achieving energy densities of up to 270 Wh / kg.

[0013] According to WO 2017 / 215900 A1, a cylindrical round cell is formed in which the electrode-separator assembly and its electrodes are ribbon-shaped and in the form of a wound body. Each electrode has a current collector on which electrode material is mounted. Electrodes of opposite polarity are arranged offset from one another within the electrode-separator assembly, so that the longitudinal end of the positive electrode current collector protrudes from one side of the wound body, and the longitudinal end of the negative electrode current collector protrudes from the other side of the wound body. Regarding electrical contact of the current collectors, the cell has a contact plate located on one end face of the wound body and connected to the longitudinal end of one current collector by welding. This allows electrical contact to be made with the current collector, and therefore with the associated electrode, over its entire length. This significantly reduces the internal resistance within the described cell. As a result, the generation of large currents can be significantly reduced, and heat from welding can also be better dissipated.

[0014] However, cells such as those described in WO 2017 / 215900 A1 always require contact between the contact plates and the housing parts or the poles passing through the housing parts via separate conductors, which require space within the housing, and their use requires additional assembly steps. Summary of the Invention [Problem to be solved by the invention]

[0015] Based on this prior art, it would be desirable to further increase the energy density of energy storage elements, in particular of the type described in WO 2017 / 215900 A1. [Means for solving the problem]

[0016] This object is achieved by an energy storage element having the features of claim 1. The object of the invention is also a manufacturing method having the features of claim 11. Preferred embodiments of the invention can be found in the dependent claims.

[0017] Storage element according to the invention In order to solve the above problems, the energy storage element according to the present invention has the following features: a. the energy storage element includes an electrode-separator assembly having an anode / separator / cathode arrangement; the anode of the electrode-separator assembly is ribbon-shaped and includes a ribbon-shaped anode current collector having a first longitudinal end and a parallel second longitudinal end; the ribbon-shaped anode current collector includes a main area on which a layer of negative electrode material is carried and a free end strip extending along a first longitudinal edge thereof and not carrying any negative electrode material; the cathode of the electrode-separator assembly is ribbon-shaped and includes a ribbon-shaped cathode current collector having a first longitudinal edge and a second longitudinal edge parallel thereto; the ribbon-shaped cathode current collector includes a main area on which a layer of positive electrode material is carried and a free end strip extending along a first longitudinal edge thereof and not carrying any positive electrode material; the electrode-separator assembly is in the form of a cylindrical winding having first and second terminal end faces and a winding shell therebetween, and includes an anode and a cathode in a spirally wound form; the anode and cathode are formed and / or arranged in an electrode-separator assembly formed as a winding, so that a free end strip of the cathode current collector or a free end strip of the anode current collector protrudes from the first terminal end face; b. the energy storage element includes a housing, the housing being sealed in an airtight and liquidtight manner and having a metal housing cup having a bottom and peripheral sidewall and a terminal opening and a lid; c. the energy storage element includes a metal portion covering the first terminal end face; d. the metal portion includes a flat area to which a free end strip protruding from the first terminal end face is welded, and a protrusion extending away from the first terminal end face; e. the bottom of the housing cup has an aperture into which the protrusion is inserted or through which the protrusion protrudes, so that the protrusion can be mechanically contacted from outside the housing; f. The bottom and the metal part are insulated from each other by an electrically insulating seal; It always has the following characteristics a. to f. The free end strip protruding from the terminal end face may be a free end strip of a cathode current collector or a free end strip of an anode current collector, preferably it is a free end strip of a cathode current collector.

[0018] In contrast to WO 2017 / 215900 A1, the energy storage element according to the present invention has a metal part that simultaneously functions as a closure means for the housing of the energy storage element, as a conductor of current from the anode or cathode current collector, and as a pole. Therefore, the separate electrical conductors known in the prior art and typically arranged between the lid or lid assembly and the contact plate, as described in WO 2017 / 215900 A1, are not required. The energy storage element according to the present invention is therefore particularly easy to manufacture. The absence of separate conductors and separate poles can reduce the internal resistance of the energy storage element and also means that more effective volume within the housing is available, which means that more active material can be introduced into the housing, increasing the energy density.

[0019] Preferred design of metal parts Preferably, the energy storage element according to the present invention is characterized by at least one of the features a. and b. immediately below: a. The protrusion of the metal portion away from the first terminal end face is formed as a cup. b. The metal part including the protrusion is an integral part.

[0020] The immediately above features a. and b. are preferably realized in combination.

[0021] The metal part with the cup-shaped protrusion can be manufactured, for example, by a deep drawing process and then preferably formed as an integral part, however, it can also be manufactured from a metal workpiece by a molding or machining manufacturing step, or it can be manufactured, for example, by 3D printing.

[0022] Preferably, the metal portion including the projection is sheet metal formed in a deep drawing process.

[0023] By employing each of these features individually, and in particular in one of the aforementioned combinations, the structural complexity of the energy storage element is further reduced compared to energy storage elements known from the prior art, which makes the overall manufacturing process even more desirable and leads to an even greater reduction in the internal resistance of the energy storage element.

[0024] Connection of one of the electrodes to the housing cup and a preferred second metal part. One electrode of the energy storage element according to the present invention is electrically connected to a metal part, preferably a first metal part, via a free end strip protruding from the first terminal end face, and the other electrode is electrically connected to a metal part, preferably a second metal part. Thus, the energy storage element according to the present invention is preferably characterized by at least one of the features a. to e. immediately below: a. The ribbon-type electrode is formed as and / or disposed within an electrode-separator assembly formed as a winding such that one free end strip of the anode or cathode current collector protrudes from a first terminal end face and the other free end strip protrudes from a second terminal end face of the electrode-separator assembly. b. The energy storage element includes a metal portion covering the first terminal end face as the first metal portion. c. A second metal portion covers the second terminal end face and is welded directly to the free end strip protruding from the second terminal end face. d. The second metal portion forms a lid for the housing. e. A second metal portion closes the end opening of the housing cup.

[0025] It is particularly preferred that the immediately above features b. and c., b. to d., b. to e. or a. to e. are realized in combination.

[0026] The free end strip protruding from the first terminal end face is preferably the free end strip of the cathode current collector, and accordingly, the end strip protruding from the second terminal end face is preferably the free end strip of the anode current collector.

[0027] In principle, it is also possible to weld a separate conductor to the second metal part and then electrically couple this to one of the electrodes, so in these cases there is no direct connection between the end strip of one current collector and the second metal part.

[0028] Preferred molding of metal parts, end openings, and seals Preferably, the energy storage element is characterized by at least one of the features a. to e. immediately below: a. The terminal opening of the housing cup has a circular shape. b. The first and / or second metal portion is a disk and has a circular end. c. The circular end of the second metal part is bent 90°. d. The seal is formed as a disk or annulus in at least some areas and has rounded ends. e. The energy storage element includes an insulating means made of an electrically insulating material, which is arranged between the end of the metal portion covering the first end face and the housing cup, and electrically insulates the end of the first metal portion from the potential of the housing cup.

[0029] The above features are preferably realized in any combination, particularly a and b, a, b and d, b and c, or a to e.

[0030] The electrically insulating material may be, for example, a polyimide-containing material that can be vapor-deposited, sprayed, or attached with an adhesive. In particular, adhesive tapes containing polyimide (e.g., DuPont's Kapton® adhesive tape) are particularly suitable as electrically insulating materials for electrically insulating the end of the (first) metal part from the potential of the housing cup.

[0031] In addition to electrically insulating the first metal part and the bottom of the housing cup from each other, the seal also serves to seal the housing from the outside, i.e., to prevent electrolyte leakage or the ingress of foreign substances into the energy storage element.

[0032] Preferred housing design Preferably, the energy storage element is characterized by at least one of features a. to c. immediately below: a. The housing includes, in axial order, a bottom portion, a center portion, and a lid closure portion. b. At the central portion, the wound shell of the electrode-separator assembly, formed as a wound body, contacts the inside of the housing cup. c. The central portion has a cylindrical shape.

[0033] The immediately above features a to c are preferably realized in combination.

[0034] The energy storage element according to the invention is preferably a cylindrical round cell, which is known to have a cylindrical housing with a generally circular base.

[0035] Preferably, the height of the energy storage element according to the invention, which is formed as a cylindrical round cell, is 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 particularly suitable for supplying power to the electric drive of automobiles.

[0036] Particularly preferably, the wound shell of the electrode-separator assembly formed as a wound body is placed directly against the inside of the housing cup of the central portion. In some cases, the inside of the housing of the central portion is electrically insulated, for example by a film. In this case, the wound shell of the electrode-separator assembly is preferably in contact with or placed against the inside of the housing cup, which is lined with foil.

[0037] The lid closure portion includes the area of ​​the cell that is closed by the lid.

[0038] Preferably, the lid closure portion and the bottom of the housing cup are located at opposite ends of the energy storage element.

[0039] Embodiments with Spacers Preferably, the energy storage element is characterized by at least one of features a. to c. immediately below: a. The metal portion covering the first end face has a first side facing the bottom of the housing cup and a second side facing the electrode-separator assembly. b. An annular spacer made of an electrically insulating material is disposed between the bottom of the housing cup and the metal portion covering the first end surface. c. The spacer, the first side of the metal portion covering the first end face, and the bottom of the housing cup form an annular gap, which is filled with a seal.

[0040] The immediately above features a to c are preferably realized in combination.

[0041] In further embodiments described above and in more detail below, the metal portion covering the first end surface may be the first metal portion.

[0042] Thermoplastic materials such as polybutylene terephthalate (PBT), polypropylene (PP), polyethylene (PE), or polyphenylene sulfide (PPS) are suitable for the spacer. The spacer has a function of maintaining a distance between the metal part covering the first end face and the bottom of the housing cup, so that the first side of the metal part covering the first end face, the spacer itself, and the bottom of the housing cup form an annular gap that can be closed by a seal.

[0043] The seal preferably consists of a potting material poured into the annular gap and cured during manufacture of the energy storage element. Solvent-resistant plastic materials are suitable for the seal, preferably thermosetting plastic materials such as epoxy resins, elastomeric plastic materials, or thermoplastic plastic materials such as polyesters. For example, the seal may be made of an epoxy resin (e.g., Henkel's Loctite® EA 9497).

[0044] Further preferred embodiments of the first and second metal parts Preferably, the energy storage element is characterized by at least one of the features a. to f. immediately below: a. The first longitudinal end along which the free end strip protruding from the first terminal end face of the electrode-separator assembly extends forms an area in which the metal portion covering the first end face is flat or pressed in at least a sub-area. b. The first longitudinal end along which the free end strip protruding from the second terminal end face of the electrode-separator assembly extends forms an area in which the metal portion covering the second end face is flat or pressed in at least a sub-area. c. The metal portion covering the first end face is sized to cover at least 40%, preferably at least 60%, and particularly preferably at least 80% of the first terminal end face. d. The metal portion covering the second end face is sized to cover at least 40%, preferably at least 60%, and most preferably at least 80% of the first terminal end face. e. The metal portion covering the first end face and / or the metal portion covering the second end face preferably has a uniform thickness within a range of 50 μm to 600 μm, and more preferably within a range of 150 μm to 350 μm. f. The protrusion of the metal portion covering the first end surface has a cylindrical shape and appears as a cylindrical depression on the second side of the metal portion and as a cylindrical ridge on the first side of the metal portion.

[0045] The immediately preceding features a and c and / or b and c are preferably implemented in combination. In further embodiments, features a and c and e and / or b and c and e are implemented in combination. Particularly preferably, features a and c and e and f and / or b and c and e and f are implemented in combination.

[0046] As already mentioned above, the protrusion of the metal part covering the first end face serves as a pole that can be electrically coupled to an external energy consumer, either indirectly via a conductor or directly by mechanical means.

[0047] Preferred Embodiments of the Lid Closure Portion In a particularly preferred embodiment, the lid is welded and sealed into the end opening of the housing cup, and the lid and housing cup then have the same polarity.

[0048] However, in another variant, the lid can also be electrically insulated from the housing cup, in which embodiment the lid can function as a pole of the energy storage element according to the invention, while the housing cup can be potential-free.

[0049] Preferably, the energy storage element in this further variant is characterized by at least one of the features a. to d. immediately below: a. The central portion and the lid closure portion are separated from each other by a radial bead around the outside of the annular housing cup. b. The energy storage element includes a seal as a first seal that electrically insulates the bottom of the housing cup and the first metal portion from each other. c. A second seal is placed within the lid closure portion, which is pressed against the two metal portions forming the lid of the housing and the inside of the housing cup. d. The second seal has an annular shape and has a circular end.

[0050] The features a. to d. immediately above are preferably realized in combination.

[0051] To achieve this, the housing cup is typically forced radially inward against the lid, thereby compressing the second seal. This can also be done as part of the crimping process, in which a radial bead around the annular periphery can play a role.

[0052] In an embodiment of the energy storage element according to the above variant, which uses a second metal part forming the lid of the housing and a second seal pressed against the inside of the housing cup, it may be preferable for the energy storage element to include a reference electrode inside the housing, which is electrically connected to the housing cup. The reference electrode may be, for example, metallic lithium or a lithium compound. Preferably, the reference electrode is in direct contact with the housing cup, in particular the inside of the housing cup. For example, the inside of the casing of the housing cup may be lined with a thin layer of lithium.

[0053] In further preferred embodiments, the energy storage element is characterized by at least one of the features a. to f. immediately below: a. The energy storage element has protection against internal overpressure within the lid closure portion. b. The second metal part forming the lid of the housing has an opening and a recessed area around the opening, the recessed area having a thickness less than that of the remainder of the second metal part. c. The opening in the second metal portion has a circular shape. d. The opening in the second metal part is closed by a membrane that is designed to burst in the event of a predetermined overpressure occurring inside the housing. e. The film is embedded within the recessed area of ​​the second metal portion. f. The surface of the membrane remote from the electrode-separator assembly extends in a common plane with the surface of the second metal component remote from the electrode-separator assembly.

[0054] The features a. to f. immediately above are preferably realized in combination.

[0055] Favorable material properties of the current collector, housing cup, and metal parts The current collectors of the energy storage element according to the invention have the function of making electrical contact over as large an area as possible with the electrochemically active components contained in the respective electrode materials, and are preferably made of metal or metallized at least on their surfaces.

[0056] The material properties of the current collector are determined inter alia by the electrochemical conditions, in particular the electrode chemistry.

[0057] In the case of an energy storage element formed as a lithium-ion cell according to the present invention, suitable metals for the anode current collector are, for example, copper or nickel, or another electrically conductive material, in particular an alloy of copper and nickel, or a metal coated with nickel. In particular, materials of the EN CW-004A or EN CW-008A type 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 steels of the 1.4303 or 1.4404 types, or of the SUS304 type, can also be considered.

[0058] For energy storage elements formed as lithium-ion cells, aluminum or another conductive material, such as an aluminum alloy, is particularly suitable as the metal for the cathode current collector.

[0059] Suitable aluminum alloys for the cathode current collector include, for example, aluminum alloys of the 1235, 1050, 1060, 1070, 3003, 5052, Mg3, Mg212 (3000 series), and GM55 types. Also suitable are AlSi, AlCuTi, AlMgSi, AlSiMg, AlSiCu, AlCuTiMg, and AlMg. The aluminum content of these alloys is preferably greater than 99.5%.

[0060] Preferably, the anode current collector and / or the cathode current collector are each a ribbon-shaped metal foil having a thickness in the range of 4 μm to 30 μm.

[0061] However, in addition to films, metallic or metallized nonwoven fabrics, or open pore metallic foams, or other ribbon-type materials such as expanded metals, can also be used as current collectors.

[0062] The current collector is preferably loaded on both sides with the respective electrode materials.

[0063] The housing cup is preferably made of aluminum, an aluminum alloy, or thin steel sheet, for example nickel-plated steel sheet. Suitable aluminum alloys for the housing cup are, for example, Al alloys of the 1235, 1050, 1060, 1070, 3003, 5052, Mg3, Mg212 (3000 series), and GM55 types. Also suitable are AlSi, AlCuTi, AlMgSi, AlSiMg, AlSiCu, AlCuTiMg, and AlMg. The aluminum content of these alloys is preferably greater than 99.5%.

[0064] The nature of the metal portion adjacent the first end face, and any second metal portion present, is determined by whether the free end strip protruding from the first terminal end face is a cathode current collector free end strip or an anode current collector free end strip.

[0065] If the free end strip protruding from the first terminal end face is the free end strip of a cathode current collector, the metal portion adjacent to the first end face is preferably made of the same or a chemically similar material as the cathode current collector, i.e. in particular made of aluminum or an aluminum alloy.

[0066] If the free end strip protruding from the first terminal end face is the free end strip of the anode current collector, the metal portion adjacent to the first end face is preferably made of the same or chemically similar material as the anode current collector, i.e., in particular copper or nickel, nickel-plated copper, an alloy of copper or nickel, or stainless steel.

[0067] In some preferred embodiments, the seal is made of an electrically insulating plastic material with a melting point >200° C., preferably >300° C. The plastic material is polyetheretherketone (PEEK), polyimide (PI), polyphenylsulfide (PPS), or polytetrafluoroethylene (PTFE).

[0068] Electrodes and electrode materials In one particularly preferred embodiment, the energy storage element according to the present invention is a lithium-ion cell.

[0069] Essentially, all known electrode materials for secondary lithium-ion cells can be used for the electrodes of the present energy storage element.

[0070] Carbon-based particles, such as graphite-like carbon, or non-graphitic carbon materials that are intercalatable with lithium and preferably also in particulate form, can be used as the active material in the anode. Separately or in addition to this, lithium titanate (Li4Ti5O 12 ) or derivatives thereof may also be included in the anode, preferably also in particulate form. Further, the anode can include, as the active material, silicon, aluminum, tin, antimony, or compounds or alloys of these materials that are capable of reversible intercalation and redeposition of lithium, such as silicon oxide (especially LiO x , where 0 < x < 2), in combination with a carbon-based active material optionally. Tin, aluminum, antimony, and silicon can form intermetallic phases with lithium. In particular, in the case of silicon, the receptable capacity for lithium can be many times that of graphite or equivalent materials. Mixtures of silicon- and carbon-based storage materials are often used. Thin anodes made of metallic lithium are also suitable.

[0071] Suitable active materials for the cathode include lithium metal oxide compounds and lithium metal phosphate compounds, such as LiCoO2 and LiFePO4. Lithium nickel manganese cobalt oxide (NMC) of the chemical formula LiNi x Mn y Co z O2 (where x + y + z is typically 1), lithium manganese spinel (LMO) of the chemical formula LiMn2O4, or lithium cobalt aluminum oxide (NCA) of the chemical formula LiNi x Co y Al z O2 (where, x + y + z is typically 1) are also particularly suitable. Derivatives of these, such as lithium nickel manganese cobalt aluminum oxide (NMCA) of the chemical formula Li 1.11 (Ni 0.40 Mn 0.39 Co 0.16 Al 0.05 ) 0.89 O2 or Li 1+xMO compounds and / or mixtures of the above materials can also be used.The cathode active material is also preferably used in particulate form.

[0072] Furthermore, the electrodes of the energy storage element according to the present invention preferably contain an electrode binder and / or an additive for improving electrical conductivity. The active material is preferably embedded in the matrix of the electrode binder, and adjacent particles in the matrix preferably directly contact each other. The conductive agent functions to increase the electrical conductivity of the electrode. Common electrode binders are based on, for example, polyvinylidene fluoride (PVDF), (Li-) polyacrylate, styrene-butadiene rubber, or carboxymethyl cellulose, or a mixture of different binders. Common conductive agents are carbon black, micronized graphite, carbon fibers, carbon nanotubes, and metal powders.

[0073] Sodium Ion-Based Embodiments In further embodiments, the energy storage element according to the present invention may be a sodium-ion cell, a potassium-ion cell, a calcium-ion cell, a magnesium-ion cell, or an aluminum-ion cell. Among these variations, energy storage elements using sodium-ion cell chemistry are particularly preferred according to the present invention.

[0074] Preferably, the sodium ion based energy storage element according to the present invention comprises 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-ethyl methyl carbonate (EC-EMC), ethylene carbonate-dimethyl carbonate-ethyl methyl 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), γ-butyrolactone (GBL) is. Trimethyl phosphate (TMP) and tris(2,2,2-trifluoroethyl) phosphate (TFP) can also be used.

[0075] Preferred conductive salts are: NaPF6, sodium difluoro(oxalato)borate (NaBOB), NaBF4, sodium bis(fluorosulfonyl)imide (NaFSI), 2-trifluoromethyl-4,5-dicyanoimidazole sodium (NaTDI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), NaAsF6, NaBF4, NaClO4, NaB(C2O4)2, NaP(C6H4O2)3; NaCF3SO3, sodium triflate (NaTf), and Et4NBF4.

[0076] In a preferred embodiment, additives can be added to the electrolyte. Examples of preferred additives, especially for stabilization, are: Fluoroethylene carbonate (FEC), trans-difluoroethylene carbonate (DFEC), ethylene sulfite (ES), vinylene carbonate (VC), bis(2,2,2-trifluoroethyl)ether (BTFE), 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).

[0077] The negative electrode material of the sodium ion-based energy storage element according to the invention is preferably at least one of the following materials: - carbon, in particular hard carbon (pure or doped with nitrogen and / or phosphorus) or soft carbon or graphene-based materials (N-doped); carbon nanotubes, graphite - Phosphorus or sulfur (conversion anode) - Polyanions: Na2Ti3O7, Na3Ti2(PO4)3, TiP2O7, TiNb2O7, Na-Ti-(PO4)3, Na-V-(PO4)3 - Prussian Blue: Low Na variant (for systems with aqueous electrolytes) - Transition metal oxides: V2O5, MnO2, TiO2, Nb2O5, Fe2O3, Na2Ti3O7, NaCrTiO4, Na4Ti5O 12 MXene with M=Ti, V, Cr, Mo, or Nb, and A=AI, Si, and Ga, and X=C and / or N, such as Ti3C2 - Organic: e.g. sodium terephthalate (Na2C8H2O4)

[0078] Alternatively, a sodium metal anode can be used on the anode side.

[0079] The positive electrode material of the sodium ion-based energy storage element according to the invention is, for example, at least one of the following materials: - Polyanions: NaFePO4(Triphylit-Typ), 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

[0080] Furthermore, the electrodes of the energy storage element according to the present invention preferably comprise an electrode binder and / or an additive for improving electrical 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 preferably directly contact each other. The conductive agent serves to increase the electrical conductivity of the electrode. Common electrode binders are, for example, based 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, micronized graphite, carbon fibers, carbon nanotubes, and metal powders.

[0081] Particularly preferably, in the energy storage element according to the invention, the current collectors of both the anode and the cathode consist of aluminum or an aluminum alloy. The housing and the contact plates, as well as any further current conductors in the housing, can also consist of aluminum or an aluminum alloy.

[0082] Preferred Materials for the Electrolyte and Separator The energy storage element according to the invention preferably comprises a liquid electrolyte, and in the case of a lithium-ion cell, in particular an electrolyte based on at least one lithium salt, for example lithium hexafluorophosphate (LiPF), which is present dissolved in an organic solvent (for example in a mixture of organic carbonates or cyclic ethers or nitriles, such as THF). Other lithium salts that can be used are, for example, lithium tetrafluoroborate (LiBF), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(oxalato)borate (LiBOB).

[0083] Like the electrodes, the separators of the electrode-separator assemblies of the energy storage elements according to the invention are preferably formed as ribbon separators. Where appropriate, the electrode-separator assemblies of the energy storage elements according to the invention include two or more ribbon separators. For example, it may be desirable to arrange a ribbon anode or ribbon cathode between two ribbon separators.

[0084] The separator is preferably made of an electrically insulating plastic film, which preferably has pores that allow the liquid electrolyte to pass through. The plastic film can be made of, for example, polyolefin or polyetherketone. Nonwoven fabrics and cloths made of plastic materials, or other electrically insulating cloths, can also be used as separators. Separators with a thickness in the range of 5 to 50 μm are preferred.

[0085] However, in principle, ribbon separators can also be separators made of solid electrolytes that have inherent ionic conductivity and do not require impregnation with a liquid electrolyte. The solid electrolyte can be, for example, a polymer solid electrolyte based on a polymer-conductive salt complex that exists in a single phase without any liquid component. The polymer matrix of the solid polymer electrolyte can be polyacrylic acid (PAA), polyethylene glycol (PEG), or polymethyl methacrylate (PMMA). Lithium conductive salts such as lithium bis-(trifluoromethane)sulfonylimide (LiTFSI), lithium hexafluorophosphate (LIPF6), and lithium tetrafluoroborate (LIBF4) can be present in these.

[0086] Preferred shapes and dimensions of electrodes and separators The anode current collector, cathode current collector, and one or more separators of an energy storage element according to the present invention preferably each have the following dimensions: - Lengths ranging from 0.5m to 25m, - Width in the range of 40mm to 145mm.

[0087] Preferred Embodiments of the Electrode-Separator Assembly The longitudinal ends of one or more separators preferably form the end faces of an electrode-separator assembly formed as a wound body.

[0088] To prevent direct contact between electrodes of opposite polarity at the axial ends of an electrode-separator assembly in the form of a cylindrical winding, separators are preferably used that are slightly wider than the electrodes to be separated. Thus, in a preferred embodiment, the electrode-separator assembly terminates at its axial end with a separator protrusion that forms the end face from which the free end strip of the current collector protrudes.

[0089] The free end strip of the current collector which projects beyond the terminal end face of the winding preferably does not project beyond the end face by more than 5500 μm, preferably not more than 4000 μm.

[0090] Particularly preferably, the free end strip of the anode current collector projects from the end face of the winding by no more than 3000 μm, particularly preferably by no more than 2000 μm, and particularly preferably, the free end strip of the cathode current collector projects from the end face of the winding by no more than 4000 μm, particularly preferably by no more than 3000 μm.

[0091] In an electrode-separator assembly formed as a winding, the ribbon-type anode, ribbon-type cathode, and ribbon-type separator are spirally wound. To produce this assembly, the ribbon-type electrode, preferably together with the ribbon-type separator, is fed to a winding device and preferably wound spirally around a winding shaft within the device. In some embodiments, for this purpose, the electrode and one or more separators are wound onto a cylindrical or hollow cylindrical winding core, which rests on a winding mandrel and remains in the coil after winding.

[0092] The wrapping shell can be formed, for example, by a plastic film or an adhesive tape. It is also possible for the wrapping shell to be formed by one or more separator wraps.

[0093] In a particularly preferred embodiment, the end faces of the electrode-separator assembly formed as a wound body are heat-treated before or during assembly, in particular in such a way that the separator protrusions at least partially melt or deform under the influence of heat. A suitable pretreatment can also be carried out to induce directional deformation of the separator protrusions. For example, the separator end forming the end face can be provided with a ceramic coating on only one side. When such a separator end is heat-treated at a suitable temperature, it curls up, and in this way the end face can be closed.

[0094] Preferably, the ribbon-type anode and ribbon-type cathode are positioned offset from one another within the electrode-separator assembly so that the free end strip of the anode current collector protrudes from one terminal end face and the free end strip of the cathode current collector protrudes from the other terminal end face.

[0095] Preferred nominal capacity of the energy storage element The lithium-ion-based energy storage elements according to the invention, configured as cylindrical round cells, preferably have a nominal capacity of up to 15,000 mAh. For a 21x70 form factor, the energy storage elements in one embodiment as lithium-ion cells preferably have a nominal capacity in the range of 1,500 mAh to 7,000 mAh, particularly preferably in the range of 3,000 mAh to 5,500 mAh. For a 18x65 form factor, the energy storage elements in one embodiment as lithium-ion cells preferably have a nominal capacity in the range of 1,000 mAh to 5,000 mAh, particularly preferably in the range of 2,000 mAh to 4,000 mAh.

[0096] In the European Union, manufacturer specifications for the nominal capacity of secondary batteries are strictly regulated. For example, information about the nominal capacity of secondary nickel-cadmium batteries must be based on measurements in accordance with standards IEC / EN 61951-1 and IEC / EN 60622, information about the nominal capacity of secondary nickel-metal hydride batteries must be based on measurements in accordance with standard IEC / EN 61951-2, information about the nominal capacity of secondary lithium batteries must be based on measurements in accordance with standard IEC / EN 61960, and information about the nominal capacity of secondary lead-acid batteries must be based on measurements in accordance with standard IEC / EN 61056-1. Any information about nominal capacity in this application is preferably based on these standards.

[0097] Mobile ion reservoir The functionality of lithium or sodium cells is based on the availability of sufficient mobile ions (mobile sodium ions in the case of sodium-ion cells, mobile lithium ions in the case of lithium-ion cells) to balance the current drawn by migration between the anode and cathode or between the negative and positive electrodes. Mobile ions, in the context of this application, mean that the ions are available for, or can be activated for, storage and retrieval processes in the electrodes as part of the discharge and charge processes of the energy storage element according to the present invention. During the discharge and charge processes of, for example, a lithium-ion cell, a reduction in mobile lithium occurs over time. This reduction occurs as a result of various generally unavoidable side reactions. The reduction in mobile ions already occurs during the first charge and discharge cycles. During this first charge and discharge cycle, a top layer typically forms on the surface of the electrochemically active component on the negative electrode. This top layer, known as the solid electrolyte interphase (SEI), typically consists of electrolyte decomposition products and, in the case of lithium-ion cells, a certain amount of lithium firmly bound within the layer.

[0098] To compensate for these losses, the sodium ion-based energy storage elements according to the present invention, in preferred embodiments, comprise a reservoir of sodium or sodium-containing material, not contained in the positive and / or negative electrodes, which can be used to compensate for the loss of mobile sodium during their operation.

[0099] Particularly suitable sodium-containing materials are, for example, Na3P and Na3N. These materials can be added, for example, to the electrode active material.

[0100] In a preferred embodiment, the lithium-ion based energy storage elements according to the present invention comprise a reservoir of lithium or lithium-containing material not contained in the positive and / or negative electrodes, which can be used to compensate for the loss of mobile lithium during their operation. For example, metallic lithium is suitable.

[0101] In a particularly preferred embodiment, the metallic lithium of the aforementioned reference electrode can serve as a lithium reservoir, and by applying a corresponding voltage to the reference electrode, the concentration of lithium ions in the electrolyte can be actively controlled in a particularly advantageous manner.

[0102] The same can be said for metallic sodium in the housing. One can also consider preloading the electrode with excess lithium or sodium ions.

[0103] Manufacturing Process The manufacturing process according to the invention is used for the manufacture of the aforementioned energy storage elements and is characterized by the following characteristics a. to e.: a. An electrode-separator assembly is provided having a housing cup having an end opening and a bottom aperture, and first and second end faces, as already defined above with respect to the energy storage element. b. A metal part is provided that includes a protrusion. c. A metal portion is disposed on the first end surface and connected by welding to the free end strip protruding from the first end surface. d. the electrode-separator assembly, together with the metal portion and the leading first end surface, is pressed into the housing cup through the distal opening of the housing cup until the protrusion is inserted into or protrudes through the aperture; e. The cavity between the metal portion and the bottom is filled with a casting compound that has electrically insulating properties when hardened.

[0104] When the potting compound hardens, it forms a seal within the annular gap previously described for the energy storage element.

[0105] Preferably, the method for manufacturing an energy storage element is characterized by at least one of features a. and b. immediately below: a. Before step c. of the above method, at least one spacer made of an electrically insulating material is placed on the bottom of the housing cup or on the metal portion to define the dimensions of the cavity between the metal portion and the bottom. b. The spacer is a disk or annulus.

[0106] Preferably, features a. and b. immediately above are implemented in combination.

[0107] Preferably, the method for producing an energy storage element additionally or alternatively comprises at least one of the following features a. to d.: a. The electrode-separator assembly is inserted into the housing cup to form and / or arrange the ribbon electrodes such that a free end strip of the anode current collector or cathode current collector projects from a first terminal end face and the other free end strip projects from a second terminal end face of the electrode-separator assembly. b. The energy storage element includes a metal portion covering the first terminal end face as the first metal portion. c. Before or after the electrode-separator assembly is inserted into the housing cup, a second metal portion is placed on the second terminal end face and connected therefrom by welding to the free end strip protruding from the second terminal end face. d. The end of the second metal part is welded around the entire periphery of the housing cup.

[0108] The immediately above features a to c or a to d are preferably realized in combination.

[0109] Preferably, the method for producing an energy storage element additionally or alternatively comprises at least one of the following features a. to c.: a. An electrolyte is filled into the interior space of the housing cup through an opening in the first or second metal part. b. The opening in the metal part is closed by a membrane that is specifically designed to burst in the event of a predetermined overpressure occurring inside the housing. c. The opening has a circular shape.

[0110] The immediately above features a and b, a and c, or a to c are preferably realized in combination.

[0111] Further combinations of features relating to the energy storage element or to the method for manufacturing the energy storage element, even if not explicitly mentioned above, can naturally be envisaged by a person skilled in the art, provided that these combinations are associated with technical synergies in view of the present invention.

[0112] Further features and advantages of the invention will become apparent from the claims and from the following description of preferred embodiments of the invention in conjunction with the drawings. The distinct features can be realized individually or in combination with one another. The drawing shows schematically: [Brief explanation of the drawings]

[0113] [Figure 1] 1 is a first embodiment of an energy storage element according to the invention in a longitudinal cross section. [Figure 2] 2 is a second embodiment of an energy storage element according to the invention in a longitudinal cross section. [Figure 3] 3 is a third embodiment of an energy storage element according to the invention in a longitudinal cross section. [Figure 4] FIG. 1 is a longitudinal cross-sectional view of an electrode-separator assembly in which a first metal portion and a second metal portion are connected by welding. [Figure 5] 1 is an electrode-separator assembly that is part of and is a component of an energy storage element according to the present invention. [Figure 6] 1 is a sequence of process steps for a method of manufacturing an energy storage element according to the present invention. [Figure 7] 4 is a fourth embodiment of an energy storage element according to the invention in a longitudinal cross section. DETAILED DESCRIPTION OF THE INVENTION

[0114] Example explanation 1 and 2 show first and second embodiments of an energy storage element 100 according to the present invention, each of which has an airtight and liquid-tight sealed housing including a metal housing cup 101 having a terminal circular opening 101 a, a bottom 101 b, a peripheral sidewall 101 c, and a lid 101 d. The bottom 101 b of the housing cup 101 has an aperture 101 e formed, for example, by a stamping process through the bottom 101 b of the housing cup 101.

[0115] The energy storage element 100 includes a metal portion 102 covering a first terminal end face 103a of an electrode-separator assembly 103 (the electrode-separator assembly is described with reference to FIG. 6 ), which in this case is formed as a first metal portion 102. The first metal portion 102 includes a flat area 102a to which a free end strip of the electrode-separator assembly 103 protruding from the first terminal end face 103a is welded, and a cup-shaped protrusion 102b facing away from the first terminal end face 103a. The metal portion 102 is a unitary part including the cup-shaped protrusion 102b and is manufactured by molding, e.g., deep drawing, or a machining manufacturing step, e.g., rolling, or 3D printing.

[0116] The cup-shaped protrusion 102b protrudes through an aperture 101e in the housing cup base 101b so that it can be mechanically contacted from outside the housing either indirectly by a conductor (not shown) or directly by an external energy consumer (not shown). The first metal part 102 is a disk having a circular end 102c, a first side 102d facing the bottom 101b of the housing cup 101, and a second side 102e facing the electrode-separator assembly 103. The cup-shaped protrusion 102b has a cylindrical shape and appears as a cylindrical depression on the second side 102e of the metal part 102 and as a cylindrical protrusion on the first side 102d of the metal part 102.

[0117] The bottom 101b and the first metal part 102 are insulated from each other by an electrically insulating seal 104, which in this case is formed as a first seal 104 and is realized by a hardened casting compound, the seal 104 being formed as a disk in at least some areas and having a circular end 104a.

[0118] Furthermore, an annular spacer 105 made of an electrically insulating material is disposed between the bottom 101b of the housing cup 101 and the first metal part 102, which together with the first side 102d of the first metal part 102 and the bottom 101b of the housing cup 101 forms an annular gap 106. The annular gap 106 is filled with a seal 104 made of a hardened casting compound.

[0119] The energy storage element 100 further includes an insulating means 107 made of an electrically insulating material, which is disposed between the circular end 102c of the first metal portion 102 and the housing cup 101 and electrically insulates the circular end 102c of the first metal portion 102 from the electrical potential of the housing cup 101. In this example, the insulating means 107 includes, at least as a component part, polyimide. In particular, the insulating material is in the form of DuPont Kapton® adhesive tape.

[0120] In a particularly preferred embodiment, instead of the insulating means 107 being separate from the spacer 105, an annular plastic component can also be arranged on the end of the metal part 102 (see Figure 4), which performs both the function of the spacer 105 and of the insulating means 107, i.e., it functions to form the annular gap mentioned above, and at the same time electrically insulates the circular end 102c of the first metal part 102 from the potential of the housing cup 101. This reduces complexity and simplifies manufacturing.

[0121] The housing cup 101 includes, in axial order, a bottom portion 101b, a cylindrical central portion 101f, and a lid closure portion 101g. In the central portion 101f, a wound shell 103b of the electrode-separator assembly 103, which is formed as a wound body, contacts the inside of the housing cup 101.

[0122] 6 is formed as a wound electrode-separator assembly 103 and disposed therein in such a way that an end strip of the current collector projects from a first terminal end face 103a and another end strip of the current collector projects from a second terminal end face 103c of the electrode-separator assembly 103. In this case, a first free end strip of the cathode current collector projects from the first terminal end face 103a of the electrode-separator assembly 103 and a free end strip of the anode current collector projects from the second terminal end face 103c of the electrode-separator assembly 103.

[0123] The free end strip of the cathode current collector protruding from the first terminal end face 103a extends along the first longitudinal end, which is only indicated by reference numeral with respect to Figure 6, and forms an area in which the first metal portion 102 is disposed. The first metal portion 102 is welded to the area formed by the free end strip of the cathode current collector and covers substantially the entire first terminal end face 103a (see Figure 4).

[0124] In addition to the first metal portion 102, the energy storage element 100 includes a second metal portion 108, which covers the second terminal end face 103c of the electrode-separator assembly and is welded directly to the free end strip of the electrode-separator assembly 103 that protrudes from the second terminal end face 103c (see FIG. 4). In the embodiment of FIGS. 1 and 2, the second metal portion 108 forms the housing lid 101d and closes the terminal circular opening 101a of the housing cup 101. Like the first metal portion 102, the second metal portion 108 is sized to cover substantially the entire second terminal end face 103c of the electrode-separator assembly 103. The second metal portion 108 is also shaped as a disk and has a circular end 108a.

[0125] Additionally, the second metal member 108 has a circular opening 108b and a recessed region 108c surrounding the circular opening 108b, the recessed region 108c having a thickness less than the remainder of the second metal member 108. The circular opening 108b of the second metal member 108 is closed by a membrane 109 that is designed to rupture in the event of a predetermined overpressure occurring inside the main interior of the housing. Thus, the membrane 109 functions as a safety device against internal overpressure within the lid closure portion 101f of the housing cup 101. The membrane 109 is recessed within the recessed region 108c of the second metal member 108, and is configured such that a surface 109a of the membrane 109 facing away from the electrode-separator assembly 103 lies in the same plane as a surface 108d of the second metal member 108 facing away from the electrode-separator assembly 103.

[0126] The first metal portion 102 and the second metal portion 108 have a substantially uniform thickness within the range of 150 μm to 350 μm.

[0127] In the first embodiment of the energy storage element 100 according to FIG. 1, the circular end 108 a of the second metal part 108 is bent by 90° and welded to the housing cup 101 all around.

[0128] 2, the central portion 101f of the housing cup 101 and the lid closure portion 101g are separated from each other by a radial bead 101h that surrounds the outside of the housing cup 101 in an annular manner. A second seal 110, arranged in the lid closure portion 101g, is in pressure contact with the second metal portion 108 and the inside of the housing cup 101, electrically insulating the two portions from each other. The second seal 110 preferably has a circular end 110a.

[0129] 3 differs from the first and second embodiments only in that the second metal part 108 is connected to the housing cup 101 by a folded closure. In this embodiment, the housing is of course not potential-free, but has an anodic or cathodic potential depending on the design.

[0130] One preferred structure of the electrode-separator assembly is shown in Figure 6. The electrode-separator assembly 103 includes a ribbon-shaped anode 111 having a ribbon-shaped anode current collector 112 and a ribbon-shaped cathode 113 having a ribbon-shaped cathode current collector 114. The anode current collector 112 is preferably a foil made of copper or nickel. The cathode current collector 114 is preferably an aluminum foil. Both the anode current collector 112 and the cathode current collector 114 have first longitudinal ends 112a, 114a and second longitudinal ends, main sections 112b, 114b, and free end strips 112c, 114c. The main sections 112b, 114b carry a layer of electrode material, either negative electrode material in the case of the anode 111 or positive electrode material in the case of the cathode 113. Free end strips 112c, 114c extend along the respective first longitudinal ends 112a, 114a and are not loaded with electrode material. Both electrodes are shown individually in an unwound state. Within the wound electrode-separator assembly 103, the anode 111 and cathode 113 are offset from one another so that the first longitudinal end 114a of the cathode current collector 114 protrudes from the first terminal end face 103a of the electrode-separator assembly 103. The first longitudinal end 112a of the anode current collector 112 protrudes from the second terminal end face 103c of the electrode-separator assembly. This is clearly visible in the bottom right image. The staggered arrangement can be seen in the bottom left image. Two ribbon-type separators 115a and 115b are also shown there, which separate the electrodes 111, 113 from one another within the wound assembly. The wound shell 103b of the electrode-separator assembly 103 is typically formed from a plastic film.

[0131] With reference to FIG. 5, a method for manufacturing the aforementioned energy storage element 100 will now be described.

[0132] In a first step, designated A, an electrode-separator assembly 103 is provided, having a housing cup 101 with a terminal circular opening 101a and an aperture 101e in a bottom 101b, as described above, and a first terminal end face 103a and a second terminal end face 103c. Additionally, a first metal portion 102 having a protrusion shaped as a cup 102a is provided. Also in step A, the first metal portion 102 is disposed on the first end face 103a and connected by welding to the free end strip 112c or 114c projecting from the first end face 103a. Additionally, in this embodiment of the method, a second metal portion 108 is provided and connected by welding to the other of the free end strips 112c or 114c projecting from the second end face 103c.

[0133] In a second step indicated by B, the electrode-separator assembly 103, together with the first metal portion 102, preferably together with the second metal portion 108 and the leading first end face 103a, is pressed into the housing cup 101 through the terminal circular opening 101a of the housing cup 101 until the cup-shaped protrusion 102a protrudes through the aperture 101e in the housing cup base 101b. An annular spacer 105 made of an electrically insulating material is placed on the housing cup base 101b or on the metal portion 102 to define the dimensions of the cavity between the metal portion 102 and the bottom 101b, in this case the aforementioned annular gap 106. If the energy storage element 100 is manufactured according to the embodiment of FIG. 1, the circular end 108a of the second metal portion is preferably welded around its entire periphery to the housing cup 101, such as by laser welding.

[0134] In a second step, indicated at C and D, the annular gap 106 between the first metal portion 102 and the bottom portion 101b is filled with a potting compound that is electrically insulating in its cured state and forms the first seal 104. The potting compound is then cured, for example, in air at room temperature, but preferably at 100°C under vacuum.

[0135] In a third step, indicated by E, electrolyte is filled into the interior space of the housing cup 101 through the circular opening 108b in the second metal part 108. Preferably, the energy storage element 100 is still under vacuum at this point, thus avoiding the unwanted intrusion of suspended matter into the housing interior.

[0136] In a final step indicated at F, the circular opening 108b in the second metal part 108 is closed by a membrane 109, which is preferably designed to burst in the event of a predetermined overpressure occurring inside the main interior of the housing. To this end, the membrane 109 is welded, such as by a laser, to the second metal part 108 in the recessed area 108c of the second metal part 108.

[0137] Alternatively, opening 108b can be closed by a rivet. In this case, the rivet has a first flange on the inside of the housing, a second flange on the outside of the housing, and a shank that passes through the opening and connects the first and second flanges. The first and second flanges close the housing portion 108 therebetween. In this case, recessed area 108c is not necessary. In a preferred embodiment, annular seals, for example, made of a suitable polymer material, can be disposed between the first flange and housing portion 108 and / or between the second flange and housing portion 108. Alternatively, the first flange and housing portion 108 and / or the second flange and housing portion 108 can be assembled by a weld line. This can be, for example, a circular weld line around opening 108b.

[0138] It will be understood that the above description of the particular embodiments shown in Figures 1 to 5 are merely preferred embodiments of the invention and do not limit the scope of protection of independent claim 1. Those skilled in the art will be able to derive other embodiments of the invention from the overall part.

[0139] 7 differs from the first and second embodiments in that the second metal portion 108 is part of a multi-piece lid assembly that includes, in addition to the metal portion 108, a metallic membrane 116, a pole cap 117, and an electrically insulating seal 110. The seal 110 insulates the membrane 116 from the metal portion 108 in the end regions, while the center of the membrane is connected to the metal portion 108, preferably by welding. If an irregular overpressure occurs within the cell, the membrane 116 can expand outward, thereby breaking the connection to the metal portion 108.

[0140] Furthermore, the energy storage element 100 has a thin lithium layer 118 inside the housing shell. This layer functions as a lithium reservoir and can compensate for the loss of lithium ions during operation. Furthermore, this layer can also function as a reference electrode, since it is in direct contact with the housing and therefore in electrical contact with it. For example, a voltage gradient can be determined between the reference electrode and the positive or negative electrode. By applying a corresponding voltage, it is also possible to specifically influence the concentration of lithium ions in the electrolyte of the energy storage element.

Claims

1. An energy storage element (100) having the following characteristics: a. The energy storage element (100) includes an electrode-separator assembly (103) having an anode (111) / separator (115a, 115b) / cathode (113) arrangement; the anode (111) of the electrode-separator assembly (103) is ribbon-shaped and includes a ribbon-shaped anode current collector (112) having a first longitudinal end (112a) and a second longitudinal end parallel thereto; the ribbon-shaped anode current collector (112) comprises a main area (112b) on which a layer of negative electrode material is carried and a free end strip (112c) extending along its first longitudinal end (112a) and on which the negative electrode material is not carried; the cathode (113) of the electrode-separator assembly (103) is ribbon-shaped and includes a ribbon-shaped cathode current collector (114) having a first longitudinal end (114a) and a second longitudinal end parallel thereto; the ribbon-shaped cathode current collector (114) includes a main area (114b) on which a layer of positive electrode material is carried and a free end strip (114c) extending along its first longitudinal end (114a) and on which the positive electrode material is not carried; the electrode-separator assembly (103) is in the form of a cylindrical winding having a first terminal end face (103a) and a second terminal end face (103c) and a winding shell (103b) located therebetween, and includes the anode (111) and the cathode (113) in a spirally wound form; the anode (111) and the cathode (113) are formed and / or arranged in the electrode-separator assembly (103) formed as a wound body, so that the free end strip (114c) of the cathode current collector (114) or the free end strip (112c) of the anode current collector (112) protrudes from the first terminal end face (103a); b. the energy storage element (100) comprises a housing, the housing having a metal housing cup (101) closed in an airtight and liquid-tight manner and having a bottom (101b) and a peripheral side wall (101c) and an end opening (101a) and a lid (101d); c. the energy storage element (100) includes a metal portion (102) covering the first terminal end face (103a); d) the metal part (102) comprises a flat area (102a) to which the free end strip (112c; 114c) protruding from the first terminal end face (103a) is welded, the flat area (102a) having the first longitudinal end (112a; 114a) forming an area on which the metal part (102) covering the first end face (103a) is placed flat or into which the metal part (102) is pressed in at least a sub-area, and a protrusion (102b) extending away from the first terminal end face (103a), the metal part (102) including the protrusion (102b) being formed as an integral part; e. the bottom (101b) of the housing cup (101) has an aperture (101e) into which the protrusion (102b) is inserted or through which the protrusion (102b) protrudes, so that the protrusion (102b) can be mechanically contacted from outside the housing; f. The bottom (101b) and the metal part (102) are insulated from each other by an electrically insulating seal (104); An energy storage element (100) having:

2. Further features include: a. The protrusion (102b) of the metal portion (102) in a direction away from the first terminal end face (103a) is shaped as a cup; b. The metal portion (102) including the protrusion (102b) is formed as an integral part; The energy storage element (100) of claim 1, comprising at least one of:

3. Further features include: a) the ribbon-type electrodes (111, 113) are formed and / or arranged in the electrode-separator assembly (103) formed as a winding, whereby one of the free end strips (112c; 114c) of the anode current collector (112) or the cathode current collector (114) protrudes from the first terminal end face (103a) and the other of the free end strips (112c; 114c) protrudes from the second terminal end face (103c) of the electrode-separator assembly (103); b. The energy storage element (100) includes a first metal portion (102) covering the first terminal end surface (103a); c. a second metal portion (108) covers the second terminal end face (103c) and is welded directly to the free end strips (112c, 114c) protruding from the second terminal end face (103c); d. the second metal part (108) forms the lid (101d) of the housing; e. the second metal part (108) closes the end opening (101a) of the housing cup (101); The energy storage element (100) of claim 1 or 2, comprising at least one of:

4. Further features include: a. The end opening (101a) of the housing cup (100) has a circular shape; b. the first and / or second metal parts (102; 108) are formed as disks and have rounded ends (102c; 108a); c. the circular end (108a) of the second metal portion is bent 90°; d. The seal (104) is formed as a disk or ring in at least a portion thereof and has an annular end (104a); e. The energy storage element (100) includes an insulating means (107) made of an electrically insulating material, the insulating means (107) being disposed between the end (102c) of the metal portion (102) covering the first end face (103a) and the housing cup (101), and electrically insulating the end (102c) of the first metal portion (102) from the potential of the housing cup (101). The energy storage element (100) according to any one of claims 1 to 3, comprising at least one of:

5. Further features include: a. said housing comprising, in axial order, said bottom portion (101b), a central portion (101f), and a lid closure portion (101g); b. In the central portion (101f), the winding shell (103b) of the electrode-separator assembly (103) formed as a winding contacts the inside of the housing cup (101); c. said central portion (101f) has a cylindrical shape; The energy storage element (100) according to any one of claims 1 to 4, comprising at least one of:

6. Further features include: a. The metal portion (102) covering the first end surface (103a) has a first side (102d) facing the bottom of the housing cup (101) and a second side (102e) facing the electrode-separator assembly; b. An annular spacer (105) made of an electrically insulating material is disposed between the bottom (101b) of the housing cup (101) and the metal part (102) covering the first end surface (103a); c) the spacer (105), the first side (102d) of the metal part (102) covering the first end surface (103a), and the bottom (101b) of the housing cup (101) form an annular gap (106) into which the seal (104) is filled; The energy storage element (100) according to any one of claims 1 to 5, comprising at least one of:

7. Further features include: a) the first longitudinal end (112a; 114a) along which the free end strip (112c; 114c) protruding from the first terminal end face (103a) of the electrode-separator assembly (103) extends defines an area over which the metal portion (102) covering the first end face (103a) is disposed flat or in which the metal portion (102) is pressed in at least a sub-area; b. The metal portion (102) covering the first end face (103a) is dimensioned to cover at least 40%, preferably at least 60%, particularly preferably at least 80% of the first terminal end face (103a); c. The metal portion (103) covering the first end surface (103a) preferably has a uniform thickness in the range of 50 μm to 600 μm, preferably in the range of 150 μm to 350 μm; d. the protrusion (102b) of the metal part (102) covering the first end face (103a) has a cylindrical shape and appears as a cylindrical depression on the second side (102e) of the metal part (102) and as a cylindrical protuberance on the first side (102d) of the metal part (102); The energy storage element (100) according to any one of claims 1 to 6, comprising at least one of:

8. Further features include: a) the first longitudinal end (112; 114a) along which the free end strip (112c; 114c) protruding from the second terminal end face (103c) of the electrode-separator assembly (103) extends defines an area in which the second metal portion (108) is placed flat or in which the second metal portion (108) is pressed in at least a sub-area; b. the second metal portion (108) is dimensioned to cover at least 40%, preferably at least 60%, particularly preferably at least 80% of the second terminal end face (103c); c. said second metal portion (108) preferably has a uniform thickness in the range of 50 μm to 600 μm, preferably in the range of 150 μm to 350 μm; The energy storage element (100) according to any one of claims 3 to 7, comprising at least one of:

9. Further features include: a. said central portion (101f) and said lid closure portion (101g) are separated from each other by a radial bead (101h) circumscribing the outside of said housing cup (101) in an annular manner; b. The energy storage element (101) includes a first seal (104) that electrically insulates the bottom of the housing cup and the first metal portion from each other; c. a second seal (110) is disposed within the lid closure portion (101g) and presses against the second metal portion (108) and the inside of the housing cup (101); d. the second seal (110) has an annular shape and has a rounded end (110a); The energy storage element (100) of claim 5, comprising at least one of:

10. Further features include: a. the energy storage element (100) has protection against internal overpressure within the lid closure portion (101g); b. the second metal portion (108) has an opening (108b) and a recessed area (108c) around the opening (108b) that has a thickness less than the remainder of the second metal portion (108); c. the opening (108b) in the second metal portion (108) has a circular shape; d. the opening (108b) of the second metal part (108) is closed by a membrane (109) designed to burst in the event of a predetermined overpressure occurring inside the main interior of the housing; e. the membrane (109) is recessed within the recessed region (108c) of the second metal portion (108); f. a surface (109a) of the membrane (109) facing away from the electrode-separator assembly (103) extends in a common plane with a surface (108d) of the second metal part (108) facing away from the electrode-separator assembly; The energy storage element (100) according to any one of claims 1 to 9, comprising at least one of:

11. A method for manufacturing an energy storage element (100) having the features of any one of claims 1 to 10, comprising the steps of: a. providing a housing cup (101) having an end opening (101a) and an aperture (101e) in said bottom (101b), and an electrode-separator assembly (103) having first and second end faces (103a, 103c), each according to claim 1; b. Providing a metal part (102) including a protrusion (102b); c) assembling said metal part (102) by placing it on said first end face (103a) and welding it to said free end strips (112c; 114c) protruding from said first end face (103a); d. pushing the electrode-separator assembly (103) together with the metal portion (102) and the leading first end face (103a) into the housing cup (101) through the distal opening (101a) of the housing cup (101) until the protrusion (102b) is inserted into the aperture (101e) or protrudes through the aperture (101e); e. filling the cavity between said metal part (102) and said bottom part (101b) with a casting compound that has electrical insulating properties when hardened; A method comprising:

12. Further features include: a) before step c) of claim 11, at least one spacer (105) made of an electrically insulating material is placed on the bottom (101b) of the housing cup (101) or on the metal part (102) to define the dimensions of the cavity between the metal part (102) and the bottom (101b); b. The spacer (105) is a disk or annular; The method of claim 11 , comprising at least one of:

13. Further features include: a. An electrode-separator assembly (103) is inserted into the housing cup (101) in which the ribbon-shaped electrodes (111; 113) are formed and / or arranged, so that the free end strips (112c; 114c) of the anode current collector (112) or the cathode current collector (114) protrude from the first terminal end face (103a), and the other of the free end strips (112c; 114c) protrude from the second terminal end face (103c) of the electrode-separator assembly (103); b. The energy storage element (100) includes, as the first metal portion (102), the metal portion (102) covering the first terminal end surface (103a); c) before or after the electrode-separator assembly (103) is inserted into the housing cup (101), a second metal portion (108) is placed on the second terminal end face (103c), where (112c; 114c) are connected by welding to the free end strips protruding from the second terminal end face (103c); d. the end (108a) of the second metal part (108) is welded to the housing cup (101) around its entire periphery; The method according to claim 11 or claim 12, comprising at least one of the following:

14. Further features include: a. An electrolyte is filled into the inner space of the housing cup (101) through the opening (108b) in the second metal part (108); b. the opening (108b) in the second metal part (108) is closed by a membrane (109) specifically designed to burst in the event of a predetermined overpressure occurring inside the main interior of the housing; c. the opening (108b) has a circular shape; The method according to any one of claims 11 to 13, comprising at least one of:

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