Energy storage element and method for producing such energy storage element

Abstract

The invention relates to an energy storage element comprising an electrode-membrane composite in a housing. The energy storage element also includes a metal piece covering a first end face of the electrode-membrane composite and welded to a free edge strip of the current collector emerging from this end face. Furthermore, the metal part comprises a projection pointing away from the end face, and the projection is pushed into a through hole in the bottom of the housing or protrudes through the through hole, so that the projection can be mechanically contacted from the outside of the housing. The invention also relates to a method for producing such an energy storage element.

Description

Technical Field

[0001] Application fields and background technologies

[0002] The invention described below relates to an energy storage element and to a method for producing such an energy storage element. Background Art

[0003] Electrochemical energy storage elements are capable of converting stored chemical energy into electrical energy by redox reactions. The simplest form of an electrochemical energy storage element is an electrochemical cell. It comprises a positive electrode and a negative electrode separated from each other by a diaphragm. During discharge, electrons are released at the negative electrode by an oxidation process. This generates an electron flow that can be drawn by an external consumer, for which the electrochemical cell serves as an energy supplier. At the same time, an ion flow corresponding to the electrode reaction is generated in the cell. This ion flow passes through the diaphragm and is realized by an ion-conducting electrolyte.

[0004] If the discharge is reversible, i.e. the conversion of chemical energy into electrical energy during discharge is reversed again and the cell is charged again, it is called a secondary cell. In secondary cells, the negative electrode is usually called the anode and the positive electrode is called the cathode, which refers to the discharge function of the electrochemical cell.

[0005] Nowadays, for many applications, secondary lithium-ion battery cells are used as energy storage elements, because they can deliver large currents and are distinguished by a relatively high energy density. Secondary lithium-ion battery cells are based on the use of lithium, which can migrate back and forth between the electrodes of the battery cell in the form of ions.

[0006] The negative electrode and the positive electrode of a lithium-ion cell are usually formed from so-called composite electrodes which, in addition to the electrochemically active components, also comprise electrochemically inactive components.

[0007] In principle, all materials that can absorb and release lithium ions again are considered as electrochemically active components (active materials) of secondary lithium-ion battery cells. For the negative electrode, for example, carbon-based particles, such as graphite carbon, are used for this purpose. For example, lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium iron phosphate (LiFePO4) or their derivatives can be used as active materials for the positive electrode. The electrochemically active materials are generally contained in the electrode in the form of particles.

[0008] As an electrochemically inactive component, the composite electrode generally includes a flat and / or strip-shaped current collector, such as a metal foil used as a carrier of the corresponding active material. The current collector of the negative electrode (anode current collector) can be formed, for example, of copper or nickel, and the current collector of the positive electrode (cathode current collector) can be formed, for example, of aluminum. In addition, the electrode can include an electrode binder (such as polyvinylidene fluoride (PVDF) or other polymers, such as carboxymethyl cellulose), additives to improve conductivity and other additives as electrochemically inactive components. The electrode binder ensures the mechanical stability of the electrode and generally also ensures the adhesion of the active material to the current collector.

[0009] As electrolyte, lithium-ion battery cells usually include a solution of a lithium salt, such as lithium hexafluorophosphate (LiPF4), in an organic solvent such as ethers and carbonates.

[0010] When producing lithium-ion battery cells, composite electrodes are usually combined with one or more separators to form an electrode-separator composite. In this case, the electrodes and separators are usually (but not necessarily) connected to each other under pressure, if necessary also by lamination or bonding. The basic functional effectiveness of the battery cell can then be produced by impregnating the composite with an electrolyte.

[0011] In many embodiments, the electrode-separator complex is designed in the form of a wound body or is processed into a wound body. In the first case, for example, a strip-shaped positive electrode and a strip-shaped negative electrode and at least one strip-shaped separator are fed separately to a winding machine and spirally wound into a wound body in the order of positive electrode (cathode) / separator / negative electrode (anode) in the winding machine. In the second case, for example, under the pressure mentioned, the strip-shaped positive electrode and the strip-shaped negative electrode and at least one strip-shaped separator are first combined into an electrode-separator complex. Then in a further step, the complex is rolled up.

[0012] For the automotive sector, electric bicycles or other applications with a high energy demand (such as tools), lithium-ion battery cells are required that have the highest possible energy density and at the same time be able to carry large currents during charging and discharging.

[0013] Typically, battery cells for the above-mentioned applications are designed as cylindrical round battery cells with a form factor of, for example, 21×70 (diameter times height in mm). This type of battery cell always includes a composite body in the form of a jellyroll. Modern lithium-ion battery cells with this form factor can already achieve energy densities of up to 270 Wh / kg.

[0014] In WO 2017 / 215900 A1, a cylindrical round battery cell is designed, in which the electrode-diaphragm complex and its electrodes are designed as strips and exist in the form of a winding body. Each electrode has a current collector loaded with electrode material. Electrodes of opposite polarity are arranged offset from each other inside the electrode-diaphragm complex, so that the longitudinal edge of the current collector of the positive electrode emerges from one side of the winding body, and the longitudinal edge of the current collector of the negative electrode emerges from the other side of the winding body. In order to make electrical contact with the current collector, the battery cell has a contact plate, which is sleeved on the end face of the winding body and connected to the longitudinal edge of one of these current collectors by welding. It can be achieved that the current collector and therefore the electrode associated with the current collector are electrically contacted over its entire length. This significantly reduces the internal resistance in the described battery cell. Therefore, the occurrence of large currents can be better managed, and heat can also be better extracted from the winding body.

[0015] However, in battery cells such as those described in WO 2017 / 215900 A1, it is always necessary to connect the contact plate to the housing part or the pole guided through the housing part via a separate electrical conductor. The separate electrical conductor requires space in the housing. In addition, its use requires additional assembly effort. Summary of the invention

[0016] Purpose and Solution

[0017] Based on this prior art, it is desirable to further increase the energy density of energy storage elements, in particular energy storage elements of the type described in WO 2017 / 215900 A1.

[0018] This object is achieved by an energy storage element having the features of claim 1. A production method having the features of claim 11 is also the subject matter of the invention. Preferred embodiments of the invention are given in the dependent claims.

[0019] Memory element according to the present invention

[0020] In order to achieve the above-mentioned objects, the energy storage element according to the invention always has the following features a. to f.:

[0021] a. The energy storage element comprises an electrode-diaphragm complex having an anode / diaphragm / cathode sequence, wherein

[0022] The anode of the electrode-separator assembly is designed in a strip shape and comprises a strip-shaped anode current collector having a first longitudinal edge and a second longitudinal edge parallel to the first longitudinal edge,

[0023] a strip-shaped anode current collector comprising a main region loaded with a layer made of negative electrode material and a free edge strip extending along a first longitudinal edge of the anode current collector and not loaded with negative electrode material,

[0024] The cathode of the electrode-separator complex is designed in a strip shape and comprises a strip-shaped cathode current collector having a first longitudinal edge and a second longitudinal edge parallel to the first longitudinal edge,

[0025] a cathode current collector in the form of a strip comprising a main region loaded with a layer made of positive electrode material and a free edge strip extending along a first longitudinal edge of the cathode current collector and not loaded with positive electrode material,

[0026] The electrode-separator complex is in the form of a cylindrical wound body having a first end face and a second end face and a wound body side face located therebetween, and the electrode-separator complex comprises an anode and a cathode in a spirally wound form,

[0027] the anode and the cathode are formed and / or arranged in an electrode-separator assembly designed as a jellyroll in such a way that a free edge strip of the cathode current collector or a free edge strip of the anode current collector emerges from a first end face,

[0028] b. The energy storage element comprises a housing sealed against air and liquid, the housing comprising a metal housing cup having a bottom and surrounding side walls and an end opening and a cover,

[0029] c. The energy storage element comprises a metal member covering the first end surface,

[0030] d. the metal member comprises: a flat region, a free edge strip emerging from the first end face is welded to the flat region; and a protrusion pointing away from the first end face,

[0031] e. The bottom of the housing cup has a through hole into which the protrusion is pushed or through which the protrusion protrudes, so that the protrusion can be mechanically contacted from outside the housing, and

[0032] f. The bottom and the metal part are insulated from each other by an electrically insulating seal.

[0033] The free edge strip emerging from the terminal end surface may be the free edge strip of the cathode current collector or the free edge strip of the anode current collector. Preferably, it is the free edge strip of the cathode current collector.

[0034] Compared to WO 2017 / 215900 A1, the energy storage element according to the present invention has a metal part, which is simultaneously used as a closing device for the housing of the energy storage element, as a conductor for the current from the anode current collector or the cathode current collector, and as a pole. Correspondingly, there is no need for a separate electrical conductor, as is known from the prior art and is usually between the cover or cover assembly and the contact plate, as described in WO 2017 / 215900 A1. Therefore, the energy storage element according to the present invention is particularly easy to manufacture. The omission of a separate conductor and a separate pole also promotes: the internal resistance of the energy storage element can be reduced, and more available volume is provided in the housing, whereby more active material can be introduced into the housing to increase the energy density.

[0035] Preferred embodiments of metal parts

[0036] Preferably, the energy storage element according to the invention is distinguished by at least one of the following features a. and b.:

[0037] a. The protrusion of the metal part pointing away from the first end face is designed to be cup-shaped.

[0038] b. The metal piece together with the protrusion is formed in one piece.

[0039] It is preferred that the features a. and b. just mentioned above are implemented in combination.

[0040] The metal part together with the cup-shaped projection can be manufactured, for example, in a deep-drawing process, and is then also preferably formed in one piece. However, this can also be produced from a metal workpiece by forming or cutting production steps or by means of 3D printing.

[0041] Preferably, the metal part together with the projection is a metal sheet formed in a deep-drawing process.

[0042] By each of these features individually and in particular by these features in one of the abovementioned combinations, the structural complexity of the energy storage element is further reduced compared to energy storage elements known from the prior art, which allows overall more advantageous production and a greater reduction in the internal resistance of the energy storage element.

[0043] One of these electrodes is attached to the housing cup and preferably the second metal piece.

[0044] One of the electrodes of the energy storage element according to the present invention is electrically connected to the metal piece as the first metal piece via a free edge strip emerging from the first end face, and another of the electrodes is preferably electrically connected to the second metal piece. Correspondingly, the uniqueness of the energy storage element according to the present invention is preferably at least one of the following features a. to e.:

[0045] a. The strip-shaped electrode is formed and / or arranged in an electrode-separator assembly designed as a winding body in such a way that one of the free edge strips of the anode current collector or the cathode current collector emerges from a first end face and the other of the free edge strips emerges from a second end face of the electrode-separator assembly.

[0046] b. The energy storage element includes a metal member covering the first end surface as the first metal member.

[0047] c. The second metal piece covers the second terminal end surface and is directly welded to the free edge strip emerging from the second terminal end surface.

[0048] d. The second metal member constitutes the cover of the housing.

[0049] e. A second metal piece closes the end opening of the housing cup.

[0050] It is particularly preferred if the features b. and c., b. to d., b. to e., or a. to e. just mentioned above are implemented in combination.

[0051] It is applicable that the free edge strip emerging from the first end face is preferably the free edge strip of the cathode current collector. Correspondingly, the edge strip emerging from the second end face is preferably the free edge strip of the anode current collector.

[0052] In principle, it is also possible to weld a separate electrical conductor to the second metal piece, which in turn is electrically connected to one of the electrodes. In these cases, therefore, there is no direct connection between the edge strip of one of the current collectors and the second metal piece.

[0053] Preferred shapes of metal parts, end openings and seals

[0054] Preferably, the energy storage element is characterized by at least one of the following features a. to e.:

[0055] a. The end opening of the housing cup is designed to be round.

[0056] b. The first metal piece and / or the second metal piece is designed to be disc-shaped and has a rounded edge.

[0057] c. The circular edge of the second metal piece is bent 90°.

[0058] d. The seal is designed to have a rounded edge and is at least partially disc-shaped or ring-shaped.

[0059] e. The energy storage element includes an insulating device made of an electrically insulating material, which is arranged between the edge of the metal piece covering the first end surface and the housing cup and electrically insulates the edge of the first metal piece from the potential of the housing cup.

[0060] It is preferred to implement the features just mentioned above in any combination, but in particular in the combination a. and b., a., b. and d., b. and c. or a. to e.

[0061] The electrically insulating material may be, for example, a polyimide-containing material which may be evaporated, injection molded or bonded. In particular, polyimide-containing adhesive tapes (e.g., from DuPont) may be used. Adhesive tape) is particularly well suited as an electrically insulating material in order to electrically insulate the edge of the (first) metal part from the electrical potential of the housing cup.

[0062] In addition to the function of electrically insulating the first metal piece and the bottom of the housing cup from each other, the seal also has the function of sealing the housing to the outside, ie preventing electrolyte leakage or foreign matter from penetrating into the energy storage element.

[0063] Optimal design of the housing

[0064] Preferably, the energy storage element is characterized by at least one of the following features a. to c.:

[0065] a. The housing comprises a bottom, a middle section and a cover closing section in axial sequence.

[0066] b. In the middle section, the jellyroll side of the electrode-separator assembly designed as a jellyroll contacts the inner side of the housing cup.

[0067] c. The middle section is designed to be columnar.

[0068] It is preferred that the features a. to c. just mentioned above are implemented in combination.

[0069] The energy storage element according to the present invention is preferably a cylindrical round battery cell. As is well known, a cylindrical round battery cell has a cylindrical housing with a generally circular bottom.

[0070] Preferably, the height of the cylindrical round battery cell of the energy storage element according to the invention is in the range of 50 mm to 150 mm. Its diameter is preferably in the range of 15 mm to 60 mm. The cylindrical round battery cell with these shape parameters is particularly suitable for providing power for the electric drive of a motor vehicle.

[0071] Particularly preferably, the jellyroll side of the electrode-diaphragm assembly designed as a jellyroll lies directly against the inner side of the housing cup in the middle section. In some embodiments, it is provided that the inner side of the housing is electrically insulated in the middle section, for example by means of a foil. In this case, the jellyroll side of the electrode-diaphragm assembly is preferably in contact with or lies against the foil-lined inner side of the housing cup.

[0072] The cover closing section includes the area of ​​the battery cell that is closed by the cover.

[0073] Preferably, the lid closing section and the bottom of the housing cup are located at mutually opposite ends of the energy storage element.

[0074] Embodiment with spacers

[0075] Preferably, the energy storage element is characterized by at least one of the following features a. to c.:

[0076] a. The metal piece covering the first end face has a first side oriented toward the bottom of the housing cup and a second side oriented toward the electrode-diaphragm assembly.

[0077] b. An annular spacer made of an electrically insulating material is arranged between the bottom of the housing cup and the metal piece covering the first end surface.

[0078] c. The spacer, the first side of the metal part covering the first end face, and the bottom of the housing cup form an annular gap, which is filled by the sealing element.

[0079] It is preferred that the features a. to c. just mentioned above are implemented in combination.

[0080] In other embodiments described in detail above and below, the metal member covering the first end surface may be a first metal member.

[0081] Suitable materials for the spacer are thermoplastic materials, such as polybutylene terephthalate (PBT), polypropylene (PP), polyethylene (PE) or polyphenylene sulfide (PPS). The spacer has the function of keeping 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, which can be filled by a sealing member.

[0082] The seal is preferably formed from a cured casting material which is poured into the annular gap during the production of the energy storage element. Suitable plastic materials for the seal are solvent-resistant plastic materials, preferably thermosetting plastic materials (such as epoxy resins), elastomeric plastic materials or thermoplastic plastic materials (such as polyesters). For example, the seal can be made of epoxy resin (for example from Henkel) EA 9497).

[0083] Other preferred designs of the first metal member and the second metal member

[0084] Preferably, the energy storage element is characterized by at least one of the following features a. to f.:

[0085] a. The first longitudinal edge along which the free edge strip extending from the first end face of the electrode-diaphragm assembly extends forms a surface on which the metal part covering the first end face is at least partially flatly placed or into which the metal part is at least partially pressed.

[0086] b. The first longitudinal edge along which the free edge strip extending from the second end face of the electrode-diaphragm assembly extends forms a surface on which the metal part covering the second end face lies at least partially flat or into which the metal part is pressed at least partially.

[0087] c. The size of the metal piece covering the first end surface is determined so that it covers at least 40%, preferably at least 60%, particularly preferably at least 80% of the first terminal end surface.

[0088] d. The size of the metal piece covering the second end face is determined so that it covers at least 40%, preferably at least 60%, particularly preferably at least 80% of the first end face.

[0089] e. The metal piece covering the first end surface and / or the metal piece covering the second end surface preferably has a uniform thickness in the range of 50 μm to 600 μm, preferably in the range of 150 μm to 350 μm.

[0090] f. The protrusion of the metal piece covering the first end surface is designed to be columnar and is in the form of a columnar groove on the second side of the metal piece and is in the form of a columnar protrusion on the first side of the metal piece.

[0091] Preferably, the features a. and c., and / or b. and c. just mentioned above are implemented in combination. In another embodiment, the features a. and c. and e., and / or b. and c. and e. are implemented in combination. It is particularly preferred that the features a. and c. and e. and f., and / or b. and c. and e. and f. are implemented in combination.

[0092] As already mentioned above, the projection of the metal part covering the first end face serves as a pole which can be electrically connected to an external energy consumer indirectly via a conductor, or also directly mechanically.

[0093] Preferred design of the cover closing section

[0094] In a particularly preferred embodiment, the cover is welded into the end opening of the housing cup for closing the end opening.The cover and the housing cup then soften to the same polarity.

[0095] However, in another variant, the cover can also be electrically insulated from the housing cup. In this embodiment, the cover can be used as a pole of the energy storage element according to the invention, and the housing cup can be potential-free.

[0096] Preferably, in this further variant, the energy storage element is distinguished by at least one of the following immediately mentioned features a. to d.:

[0097] a. The intermediate section and the cover closing section are separated from one another by a radial bead which surrounds the outer side of the housing cup in an annular manner.

[0098] 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 member from each other.

[0099] c. A second seal is arranged in the cover closing section and is in pressure contact with the second metal part forming the cover of the housing and the inner side of the housing cup.

[0100] d. The second seal is designed to be annular and has a rounded edge.

[0101] It is preferred that the features a. to d. just mentioned above are implemented in combination.

[0102] In order to produce the pressure contact, the housing cup is usually pressed radially inwards against the cover, which causes the second seal to be compressed. This can also be done within the scope of a crimping process in which the annularly surrounding radial bead can act.

[0103] In the embodiment of the energy storage element according to the above variant with a second seal which is in pressure contact with the second metal part forming the cover of the housing and the inner side of the housing cup, it can be preferred that the energy storage element comprises a reference electrode in the housing, which is electrically connected to the housing cup. The reference electrode can be, for example, metallic lithium or a lithium compound. Preferably, the reference electrode is in direct contact with the housing cup, in particular with the inner side of the housing cup. For example, the inner side of the side surface of the housing cup can be lined with a thin layer formed by lithium.

[0104] In a further preferred embodiment, the energy storage element is distinguished by at least one of the following features a. to f.:

[0105] a. The energy storage element has a protection device against internal overpressure in the cover closing section.

[0106] b. The second metal member constituting the cover member of the housing has an opening and a recessed area surrounding the opening, and the thickness of the second metal member is reduced in the recessed area compared to the remaining portion.

[0107] c. The opening of the second metal piece is designed to be circular.

[0108] d. The opening of the second metal part is closed by a diaphragm which is designed to rupture under a certain overpressure prevailing in the interior of the housing.

[0109] e. The diaphragm enters the recessed area of ​​the second metal part.

[0110] f. The surface of the membrane facing away from the electrode-diaphragm assembly and the surface of the second metal part facing away from the electrode-diaphragm assembly extend in a common plane.

[0111] It is preferred that the features a. to f. just mentioned above are implemented in combination.

[0112] Preferred material properties for current collector, housing cup and metal parts

[0113] The current collector of the energy storage element according to the present invention is used to make electrical contact with the electrochemically active components contained in the corresponding electrode material over as large an area as possible. Preferably, the current collector is made of metal or is metallized at least on the surface.

[0114] The material properties of the current collector depend inter alia on the electrochemical conditions, especially the electrode chemistry.

[0115] In the case of an energy storage element designed as a lithium-ion battery cell according to the invention, copper or nickel or other conductive materials, in particular copper alloys and nickel alloys or nickel-coated metals, for example, are suitable as the metal of the anode current collector. 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. In particular, alloys of the NiFe, NiCu, CuNi, NiCr and NiCrFe type are considered as nickel alloys. In principle, stainless steels, for example 1.4303 or 1.4404 type or SUS304 type stainless steels, can also be considered.

[0116] In the case of energy storage elements designed as lithium-ion battery cells, aluminum or other electrically conductive materials (including aluminum alloys) are particularly suitable as metals for the cathode current collector.

[0117] Suitable aluminum alloys for the cathode current collector are, for example, aluminum alloys of the 1235, 1050, 1060, 1070, 3003, 5052, Mg3, Mg212 (3000 series) and GM55 types. In addition, AlSi, AlCuTi, AlMgSi, AlSiMg, AlSiCu, AlCuTiMg and AlMg are also suitable. The aluminum content of the alloys mentioned is preferably greater than 99.5%.

[0118] Preferably, the anode current collector and / or the cathode current collector are each a strip-shaped metal foil having a thickness ranging from 4 μm to 30 μm.

[0119] In addition to foils, however, other strip-shaped substrates such as metal or metallized nonwovens or open-pore metal foams or expanded metals can also be used as current collectors.

[0120] The current collector is preferably loaded with the corresponding electrode material on both sides.

[0121] The housing cup is preferably made of aluminum, an aluminum alloy or sheet steel (e.g. nickel-plated sheet steel). Suitable aluminum alloys for the housing cup are, for example, aluminum alloys of the 1235, 1050, 1060, 1070, 3003, 5052, Mg3, Mg212 (3000 series) and GM55 types. In addition, AlSi, AlCuTi, AlMgSi, AlSiMg, AlSiCu, AlCuTiMg and AlMg are also suitable. The aluminum content of the alloys mentioned is preferably greater than 99.5%.

[0122] The nature of the metal piece in contact with the first end face and of the second metal piece that may be present depends on whether the free edge strip emerging from the first end face is the free edge strip of the cathode current collector or the free edge strip of the anode current collector.

[0123] If the free edge strip emerging from the first end face is the free edge strip of the cathode current collector, it is preferred that the metal piece abutting the first end face is made of the same material as the cathode current collector or a chemically similar material, ie, in particular, aluminum or an aluminum alloy.

[0124] If the free edge strip emerging from the first end face is the free edge strip of the anode current collector, it is preferred that the metal part adjacent to the first end face is made of the same material or a material with similar chemical properties as the anode current collector, that is, in particular copper or nickel, nickel-plated copper, or a copper alloy or a nickel alloy, or stainless steel.

[0125] In some preferred embodiments, the seal is preferably made of an electrically insulating plastic material with a melting point > 200° C., preferably > 300° C. The plastic material is polyetheretherketone (PEEK), polyimide (PI), polyphenylene sulfide (PPS) or polytetrafluoroethylene (PTFE).

[0126] Electrodes and electrode materials

[0127] In a particularly preferred embodiment, the energy storage element according to the invention is a lithium-ion battery cell.

[0128] Basically all electrode materials known for secondary lithium-ion cells can be used for the electrodes of the energy storage element.

[0129] In the anode, carbon-based particles (such as graphite-type carbon) or non-graphite carbon materials capable of being used for lithium intercalation (preferably also in the form of particles) can be used as the active material. Alternatively or additionally, lithium titanate (Li4Ti5O 12 ) or its derivatives (preferably also in the form of particles) can also be included in the anode. In addition, as the active material, the anode can include at least one material selected from the group consisting of silicon, aluminum, tin, and antimony or compounds or alloys of these materials capable of reversibly embedding and de-embedding lithium (such as silicon oxide (especially LiO x , where 0 < x < 2)), optionally in combination with a carbon-based active material. In addition, tin, aluminum, antimony, and silicon can form intermetallic phases with lithium. Here, especially in the case of silicon, the ability to absorb lithium is many times greater than that of graphite or similar materials. Mixtures of silicon-based and carbon-based storage materials are usually used. In addition, thin anodes made of metallic lithium are also suitable.

[0130] For the cathode, for example, lithium-metal oxide compounds and lithium-metal phosphate compounds (such as LiCoO2 and LiFePO4) are considered as active materials. In addition, lithium nickel manganese cobalt oxides (NMC) with the general formula LiNi x Mn y Co z O2 (where x + y + z is usually 1), lithium manganese spinel (LMO) with the general formula LiMn2O4, or lithium cobalt aluminum oxides (NCA) with the general formula LiNi x Co y Al z O2 (where x + y + z is usually 1) are particularly suitable. Their derivatives can also be used, such as lithium nickel manganese cobalt aluminum oxides (NMCA) with the general formula Li 1.11 (Ni 0.40 Mn 0.39 Co 0.16 Al 0.05 ) 0.89 O2 or Li 1+x M-O compounds and / or mixtures of the above materials. The cathode active material is preferably also used in the form of particles.

[0131] In addition, the electrodes of the energy storage element according to the present invention preferably include an electrode binder and / or an additive for improving conductivity. The active material is preferably embedded in a matrix made of an electrode binder, where adjacent particles in the matrix preferably contact directly. Conductive agents are used to improve the conductivity of the electrode. Common electrode binders are, for example, based on polyvinylidene fluoride (PVDF), polyacrylate (lithium), styrene-butadiene rubber, or carboxymethyl cellulose or mixtures of different binders. Common conductive agents include carbon black, fine graphite, carbon fiber, carbon nanotubes, and metal powder.

[0132] Sodium-based implementation

[0133] In other embodiments, the energy storage element according to the invention can also be a sodium ion battery cell, a potassium ion battery cell, a calcium ion battery cell, a magnesium ion battery cell or an aluminum ion battery cell. According to the invention, among these variants, energy storage elements with sodium ion battery chemistry are particularly preferred.

[0134] Preferably, the energy storage element of the present invention based on sodium ions comprises an electrolyte comprising at least one of the following solvents and at least one of the following conductive salts:

[0135] In particular, organic carbonates, ethers, nitriles and mixtures thereof come into consideration as solvents. Preferred examples are:

[0136] -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)

[0137] -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)

[0138] -Nitrile: acetonitrile (ACN), adiponitrile (AON), y-butyrolactone (GBL)

[0139] Furthermore, trimethyl phosphate (TMP) and tris(2,2,2-trifluoroethyl)phosphate (TFP) may also be considered.

[0140] Preferred conductive salts are:

[0141] NaPF6, sodium difluoro(oxalato)borate (NaBOB), NaBF4, sodium bis(fluorosulfonyl)imide (NaFSI), sodium 2-trifluoromethyl-4,5-dicyanoimidazole (NaTDI), sodium bis(trifluoromethylsulfonyl)imide (NaTFSI), NaAsF6, NaBF4, NaClO4, NaB(C2O4)2, NaP(C6H4O2)3; NaCF3SO3, sodium trifluoromethanesulfonate (NaTf) and Et4NBF4.

[0142] In a preferred embodiment, additives may be added to the electrolyte. Examples of preferred additives, particularly additives for stabilization, are as follows:

[0143] Fluorinated ethylene carbonate (FEC), trans-difluoroethylene carbonate (DFEC), ethylene sulfite (ES), ethylene carbonate (VC), bis(2,2,2-trifluoroethyl) ether (BTFE), sodium 2-trifluoromethyl-4,5-dicyanoimidazole (NaTDI), sodium bis(fluorosulfonyl)imide (NaFSI), aluminum chloride (AICI3), vinyl sulfate (DTD), sodium difluorophosphate (NaPO2F2), sodium difluoro(oxalato)borate (NaODFB), sodium difluorobisoxalatophosphate (NaDFOP) and tris(trimethylsilyl)borate (TMSB).

[0144] The negative electrode material of the energy storage element of the present invention based on sodium ions is preferably at least one of the following materials:

[0145] - carbon, particularly preferably hard carbon (pure or with nitrogen and / or phosphorus doping) or soft carbon or graphene-based materials (with N doping); carbon nanotubes, graphite

[0146] - Phosphorus or sulfur (conversion anode)

[0147] - Polyanions: Na2Ti3O7, Na3Ti2(PO4)3, TiP2O7, TiNb2O7, Na-Ti-(PO4)3, Na-V-(PO4)3

[0148] -Prussian Blue: Low sodium variant (for systems with aqueous electrolytes)

[0149] - Transition metal oxides: V2O5, MnO2, TiO2, Nb2O5, Fe2O3, Na2Ti3O7, NaCrTiO4, Na4Ti5O 12

[0150] -MXene, where M = Ti, V, Cr, Mo or Nb, and A = Al, Si and Ga, and X = C and / or N, such as Ti3C2

[0151] -Organic: such as sodium terephthalate (Na2C8H2O4)

[0152] Alternatively, it is in principle also possible to use a Na metal anode on the anode side.

[0153] The positive electrode material of the energy storage element of the present invention based on sodium ions is, for example, at least one of the following materials:

[0154] - Polyanions: NaFePO4 (lithium iron phosphate type), Na2Fe-(P2O7), Na4Fe3(PO4)2(P2O7), Na2FePO4F, Na / Na2[Fe 1 / 2 Mn 1 / 2 ]PO4F, Na3V2(PO4)2F3, Na3V2(PO4)3, Na4(CoMnNi)3(PO4)2P2O7, NaCoPO4, Na2CoPO4F

[0155] -Silicate: Na2MnSiO4, Na2FeSiO4

[0156] -Layered oxides: NaCoO2, NaFeO2, NaNiO2, NaCrO2, NaVO2, NaTiO2, Na(FeCo)O2, Na(NiFeCo)3O2, Na(NiFeMn)O2, Na(NiFeCoMn)O2, Na(NiMnCo)O2

[0157] In addition, the electrode of the energy storage element according to the present invention preferably includes an electrode binder and / or an additive for improving conductivity. The active material is preferably embedded in a matrix made of an electrode binder, wherein the active material is preferably used in the form of particles, and adjacent particles in the matrix are preferably in direct contact with each other. The conductive agent is used to improve the conductivity of the electrode. Common electrode binders are based on polyvinylidene fluoride (PVDF), polyacrylate (sodium), styrene-butadiene rubber, alginate (sodium) or carboxymethyl cellulose or a mixture of different binders. Common conductive agents include carbon black, fine graphite, carbon fiber, carbon nanotubes and metal powders.

[0158] Particularly preferably, in the energy storage element according to the invention, both the anode current collector and the cathode current collector are made of aluminum or an aluminum alloy. The housing and the contact plates and, if necessary, further current conductors present in the housing can also be made of aluminum or an aluminum alloy.

[0159] Preferred material embodiments for electrolyte and separator

[0160] The energy storage element according to the invention preferably comprises a liquid electrolyte, in the case of lithium-ion battery cells, in particular an electrolyte based on at least one lithium salt, for example lithium hexafluorophosphate (LiPF6) dissolved in an organic solvent (for example a mixture of organic carbonates or cyclic ethers such as THF or nitrile). Other lithium salts that can be used are, for example, lithium tetrafluoroborate (LiBF4), lithium bistrifluoromethylsulfonyl imide (LiTFSI), lithium bisfluorosulfonyl imide (LiFSI) and lithium bisoxalatoborate (LiBOB).

[0161] The separator of the electrode-separator complex of the energy storage element according to the present invention is preferably designed in a strip shape like the electrode. If necessary, the electrode-separator complex of the energy storage element according to the present invention includes more than one strip-shaped separator. Thus, for example, it may be preferred that a strip-shaped anode or a strip-shaped cathode is arranged between two strip-shaped separators.

[0162] The separator is preferably formed by an electrically insulating plastic foil. The separator preferably has pores so that it can be penetrated by the liquid electrolyte. The plastic foil can be composed of polyolefin or polyether ketone, for example. Nonwovens and fabrics made of plastic materials or other electrically insulating flat moldings can also be used as separators. Preferably, a separator with a thickness in the range of 5 μm to 50 μm is used.

[0163] However, it is also possible in principle for the strip diaphragm to be a diaphragm made of a solid electrolyte that has inherent ion conductivity and does not have to be impregnated with a liquid electrolyte. The solid electrolyte can be, for example, a polymer solid electrolyte based on a polymer conductive salt complex, which exists in a single phase without any liquid component. As a polymer matrix, the polymer solid electrolyte can have polyacrylic acid (PAA), polyethylene glycol (PEG) or polymethyl methacrylate (PMMA). Among them, lithium conductive salts can be present, such as lithium bistrifluoromethylsulfonyl imide (LiTFSI), lithium hexafluorophosphate (LIPF6) and lithium tetrafluoroborate (LIBF4).

[0164] Preferred shapes and sizes of electrodes and separators

[0165] The anode current collector, cathode current collector and the separator or separators of the energy storage element according to the present invention preferably each have the following dimensions:

[0166] - lengths ranging from 0.5m to 25m,

[0167] - A width in the range of 40 mm to 145 mm.

[0168] Preferred embodiments of the electrode-separator complex

[0169] Preferably, the longitudinal edge or edges of the separator form the end faces of the electrode-separator assembly designed as a coil.

[0170] In order to prevent electrodes of opposite polarity from coming into direct contact at the axial ends of an electrode-separator assembly in the form of a cylindrical jellyroll, a separator is preferably used which is slightly wider than the electrodes to be separated. Therefore, in a preferred embodiment, the electrode-separator assembly at its axial ends each ends with a separator projection which in turn forms the end faces from which the free edge strips of the current collector emerge.

[0171] Preferably, the free edge strip of the current collector emerging from the terminal end face of the wound body protrudes from the end face by no more than 5500 μm, preferably no more than 4000 μm.

[0172] Particularly preferably, the free edge strip of the anode current collector protrudes no more than 3000 μm, particularly preferably no more than 2000 μm from the end face of the jellyroll. Particularly preferably, the free edge strip of the cathode current collector protrudes no more than 4000 μm, particularly preferably no more than 3000 μm from the end face of the jellyroll.

[0173] In the electrode-separator complex designed as a jellyroll, there are spirally wound strip-shaped anodes, strip-shaped cathodes and one or more strip-shaped separators. In order to produce the complex, the strip-shaped electrode is preferably supplied together with the strip-shaped separator or separators to a winding device and is preferably wound spirally around a winding axis in the winding device. In some embodiments, for this purpose, the electrode and the separator or separators are wound on a cylindrical or hollow cylindrical jellyroll core, which is sleeved on a winding mandrel and remains in the jellyroll after winding.

[0174] The jelly roll side can be formed, for example, by a plastic foil or an adhesive tape. It can also be realized that the jelly roll side is formed by one or more turns of a separator.

[0175] In a particularly preferred embodiment, the end face of the electrode-diaphragm assembly designed as a wound body is heat-treated before or during the assembly of the electrode-diaphragm assembly, in particular in such a way that the membrane extension at least partially melts or deforms under the action of heat. By means of a corresponding pretreatment, the membrane extension can also be subjected to a directional deformation. For example, the membrane edge forming the end face can be provided with a ceramic coating only on one side. If such a membrane edge is heat-treated at a suitable temperature, it rolls up and the end face can be closed in this way.

[0176] Preferably, the strip-shaped anode and the strip-shaped cathode in the electrode-separator complex are arranged offset from each other to ensure that the free edge strip of the anode current collector emerges from one of the end faces and the free edge strip of the cathode current collector emerges from the other of the end faces.

[0177] Preferred rated capacity of energy storage element

[0178] The rated capacity of the energy storage element according to the invention, which is based on lithium ions and is designed as a cylindrical round battery cell, is preferably up to 15000 mAh. In the embodiment as a lithium ion battery cell, the energy storage element with a 21×70 form factor preferably has a rated capacity in the range of 1500 mAh to 7000 mAh, particularly preferably in the range of 3000 mAh to 5500 mAh. In the embodiment as a lithium ion battery cell, the energy storage element with a 18×65 form factor preferably has a rated capacity in the range of 1000 mAh to 5000 mAh, particularly preferably in the range of 2000 mAh to 4000 mAh.

[0179] In the European Union, manufacturer information about the rated capacity of secondary batteries is strictly regulated. For example, information about the rated capacity of secondary nickel-cadmium batteries should be based on measurements according to standards IEC / EN 61951-1 and IEC / EN 60622, information about the rated capacity of secondary nickel-metal hydride batteries should be based on measurements according to standard IEC / EN 61951-2, information about the rated capacity of secondary lithium batteries should be based on measurements according to standard IEC / EN 61960, and the rated capacity of secondary lead-acid batteries should be based on measurements according to standard IEC / EN 61056-1. Any specifications about the rated capacity in this application are preferably also based on these standards.

[0180] Mobile Ionic Library

[0181] The function of a lithium or sodium cell is based on providing enough mobile ions (mobile sodium ions in the case of a sodium ion cell and mobile lithium ions in the case of a lithium ion cell) to compensate for the intercepted current by migrating between the anode and the cathode or between the negative electrode and the positive electrode. "Mobile ions" within the scope of the present application can be understood as ions that are available for the process of embedding into or de-embedding from the electrode within the scope of the discharge process and charging process of the energy storage element according to the invention, or ions that can be activated for this purpose. In the course of the discharge and charging process, for example, of a lithium ion cell, losses of mobile lithium are caused over time. These losses occur due to various side reactions that are usually unavoidable. Mobile ion losses occur already during the first charge and discharge cycle. In the first charge and discharge cycle, a covering layer is usually formed on the surface of the electrochemically active components at the negative electrode. This covering layer is called a solid electrolyte interphase (Solid Electrolyte Interphase, SEI) and is usually formed mainly by electrolyte decomposition products and in the case of a lithium ion cell by a certain amount of lithium that is firmly bound in this layer.

[0182] In order to compensate for these losses, in a preferred embodiment the energy storage element according to the invention based on sodium ions comprises a sodium reservoir or a sodium-containing material reservoir which is not contained in the sodium of the positive electrode and / or the negative electrode, by means of which the losses of mobile sodium can be compensated during its operation.

[0183] Particularly suitable as the sodium-containing material are, for example, Na 3 P and Na 3 N. For example, these materials can be added to the electrode active material.

[0184] In a preferred embodiment, the lithium-ion-based energy storage element according to the invention comprises a lithium reservoir or a lithium-containing material reservoir which is not contained in the positive electrode and / or the negative electrode sodium, by means of which losses of mobile lithium can be compensated during its operation.

[0185] For example, metallic lithium is suitable.

[0186] In a particularly preferred embodiment, the metallic lithium of the reference electrode described above can be used as a lithium reservoir. By applying a corresponding voltage to the reference electrode, the concentration of lithium ions in the electrolyte can be actively controlled particularly advantageously.

[0187] A similar situation may also be envisaged in the case of metallic sodium in the shell.

[0188] It is also conceivable to charge the electrodes with an excess of lithium ions or sodium ions by precharging.

[0189] Manufacturing method

[0190] The manufacturing method according to the invention is used to manufacture the energy storage element described above and is characterized by the following immediately mentioned features a. to e.:

[0191] a. Providing a housing cup with an end opening and a through hole in the bottom and an electrode-diaphragm complex with a first end face and a second end face, respectively as already defined above for the energy storage element.

[0192] b. Providing a metal piece, the metal piece comprising a protrusion.

[0193] c. Arranging the metal piece on the first end surface and connecting it to the free edge strip emerging from the first end surface by welding.

[0194] d. pushing the electrode-diaphragm complex together with the metal part and with the first end face facing forward through the end opening of the housing cup into the housing cup, far enough that the projection is pushed into the through-hole or protrudes through the through-hole,

[0195] e. Filling the cavity between the metal part and the bottom with a casting material having electrical insulating properties in the solidified state.

[0196] When the casting compound solidifies, it forms the above-mentioned seal for the energy storage element in the annular gap.

[0197] Preferably, the method for producing an energy storage element is characterized by at least one of the following features a. and b.:

[0198] a. Prior to step c. of the method described above, at least one spacer made of an electrically insulating material is arranged on the bottom of the housing cup or on the metal part to determine the size of the cavity between the metal part and the bottom.

[0199] b. The spacer is designed to be disk-shaped or ring-shaped.

[0200] Preferably, features a. and b. just mentioned above are implemented in combination.

[0201] Preferably, the method for producing an energy storage element is characterized additionally or alternatively by at least one of the following features a. to d.:

[0202] a. Pushing the electrode-diaphragm complex into the housing cup, wherein the strip-shaped electrodes are formed and / or arranged so that one of the free edge strips of the anode current collector or cathode current collector emerges from a first end face and the other of these free edge strips emerges from a second end face of the electrode-diaphragm complex.

[0203] b. The energy storage element includes a metal member covering the first end surface as the first metal member.

[0204] c. Before or after the electrode-diaphragm assembly has been inserted into the housing cup, a second metal part is arranged on the second end face and connected there by welding to the free edge strip emerging from the second end face.

[0205] d. The edge of the second metal piece is welded to the housing cup at its periphery.

[0206] It is preferred that the features a. to c., or a. to d. just mentioned above are implemented in combination.

[0207] Preferably, the method for producing an energy storage element is characterized additionally or alternatively by at least one of the following features a. to c.:

[0208] a. Filling the interior space of the housing cup with electrolyte through the openings in the first and second metal pieces.

[0209] b. The opening in the metal part is closed, in particular, by means of a diaphragm which is designed to rupture at a certain overpressure prevailing in the interior of the housing.

[0210] c. The opening is designed to be circular.

[0211] Preferably, the features a. and b., a. and c., or a. to c. just mentioned above are implemented in combination.

[0212] Of course, other combinations of features related to energy storage elements or methods for manufacturing energy storage elements (even if they are not explicitly listed above) are also conceivable to those skilled in the art, as long as the synergistic technical effects based on the present invention are combined with these combinations. BRIEF DESCRIPTION OF THE DRAWINGS

[0213] Other features and advantages of the present invention are derived from the claims and the following description of preferred embodiments of the present invention in conjunction with the accompanying drawings. Here, each feature can be implemented separately or in combination with each other.

[0214] Schematically in the accompanying drawings:

[0215] Figure 1 A first embodiment of an energy storage element according to the invention is shown in a longitudinal sectional view;

[0216] Figure 2 A second embodiment of the energy storage element according to the invention is shown in a longitudinal sectional view;

[0217] Figure 3 A third embodiment of the energy storage element according to the invention is shown in a longitudinal sectional view;

[0218] Figure 4 A longitudinal cross-sectional view of an electrode-diaphragm assembly is shown, to which a first metal part and a second metal part are connected by welding;

[0219] Figure 5 An electrode-diaphragm assembly and its components are shown, which is a component of the energy storage element according to the invention;

[0220] Figure 6 shows a sequence of method steps for producing an energy storage element according to the invention; and

[0221] Figure 7 A fourth embodiment of an energy storage element according to the invention is shown in a longitudinal section. DETAILED DESCRIPTION

[0222] Figure 1 and Figure 2The first and second embodiments of the energy storage element 100 according to the invention are shown, each of which comprises a housing sealed against air and liquid, the housing comprising a metal housing cup 101 having a terminal circular opening 101a, a bottom 101b, a surrounding side wall 101c and a cover 101d. The bottom 101b of the housing cup 101 has a through hole 101e, which is produced, for example, through the bottom 101b of the housing cup 101 by means of a punching process.

[0223] The energy storage element 100 includes a metal member 102, which covers a first end surface 103a of an electrode-diaphragm complex 103 (the electrode-diaphragm complex will be referred to as Figure 6 The first metal part 102 is a metal part 102 having a first shape and a second shape (e.g., ... second shape (e.g., a second shape (e.g., a second shape (e.g., a second shape (e.g., a second shape (e.g., a second shape (e.g., a second shape (e.g

[0224] The cup-shaped projection 102b protrudes through a through hole 101e in the housing cup bottom 101b so that the cup-shaped projection 102b can be mechanically contacted by an external energy consumer (not shown) from outside the housing - indirectly via a conductor (not shown) or directly mechanically contacted. The first metal part 102 is designed in the form of a disk, with a rounded edge 102c, a first side 102d oriented toward the bottom 101b of the housing cup 101, and a second side 102e oriented toward the electrode-diaphragm complex 103. The cup-shaped projection 102b is designed in the form of a column and is in the form of a columnar recess on the second side 102e of the metal part 102 and in the form of a columnar protrusion on the first side 102d of the metal part 102.

[0225] The bottom 101 b and the first metal part 102 are insulated from one another by an electrically insulating seal 104 , which is designed here as a first seal 104 and is realized by the solidified casting compound, wherein the seal 104 is designed at least partially disk-shaped and has a rounded edge 104 a .

[0226] Furthermore, an annular spacer 105 made of an electrically insulating material is arranged between the bottom 101b of the housing cup 101 and the first metal part 102, which forms an annular gap 106 together with the first side 102d of the first metal part 102 and the bottom 101b of the housing cup 101. The annular gap 106 is filled by a seal 104 formed by the solidified casting compound.

[0227] In addition, the energy storage element 100 includes an insulating device 107 made of an electrically insulating material, which is arranged between the circular edge 102c of the first metal member 102 and the housing cup 101 and electrically insulates the circular edge 102c of the first metal member 102 from the potential of the housing cup 101. In this embodiment, the insulating device 107 includes at least polyimide as a subcomponent. Specifically, the insulating device is a polyimide from DuPont In the form of tape.

[0228] In a particularly preferred embodiment, instead of the insulating element 107 which is separate from the spacer 105, an insulating element 107 may also be provided on the edge of the metal element 102 (see Figure 4 ) An annular plastic component is provided, which fulfills the functions of the spacer 105 and the insulating device 107, that is, it is used to form the mentioned annular gap and to electrically insulate the circular edge 102c of the first metal part 102 from the potential of the housing cup 101. This reduces complexity and simplifies production.

[0229] The housing cup 101 comprises, in axial sequence, a bottom 101b, a cylindrical middle section 101f and a cover closing section 101g. In the middle section 101f, the jelly roll side 103b of the electrode-diaphragm assembly 103 designed as a jelly roll contacts the inner side of the housing cup 101.

[0230] Strip electrodes (such as Figure 6 The cathode current collector is formed and arranged in an electrode-separator complex 103 designed as a winding body in such a way that an edge strip of one current collector emerges from a first end face 103a of the electrode-separator complex 103 and an edge strip of another current collector emerges from a second end face 103c. In this context, a first free edge strip of the cathode current collector emerges from a first end face 103a of the electrode-separator complex, and a free edge strip of the anode current collector emerges from a second end face 103c of the electrode-separator complex 103.

[0231] The free edge strip of the cathode current collector emerging from the first terminal end surface 103a is along the reference Figure 6 The first longitudinal edge, which is not provided with a reference numeral, extends and forms the surface on which the first metal member 102 is placed herein. The first metal member 102 is welded to the surface formed by the free edge strip of the cathode current collector and substantially covers the entire first terminal end face 103a (see Figure 4 ).

[0232] In addition to the first metal member 102, the energy storage element 100 further comprises a second metal member 108, which covers the second end face 103c of the electrode-diaphragm complex and is directly welded to the free edge strip of the electrode-diaphragm complex 103 emerging from the second end face 103c (see Figure 4 ).exist Figure 1 and Figure 2 In the embodiment of the present invention, the second metal piece 108 forms a cover 101d of the housing and closes the end circular opening 101a of the housing cup 101. Like the first metal piece 102, the size of the second metal piece 108 is also determined so that it substantially covers the entire second end face 103c of the electrode-diaphragm assembly 103. The second metal piece 108 is also designed in a disc shape and has a rounded edge 108a.

[0233] The second metal part 108 also has a circular opening 108b and a recessed area 108c around the circular opening 108b, in which the thickness is reduced compared to the rest of the second metal part 108. The circular opening 108b of the second metal part 108 is closed by a diaphragm 109, which is designed to rupture under a certain overpressure prevailing inside the housing. The diaphragm 109 thus serves as a safety device against internal overpressure in the cover closing section 101f of the housing cup 101. The diaphragm 109 enters the recessed area 108c of the second metal part 108 and is designed so that the surface 109a of the diaphragm 109 facing away from the electrode-diaphragm complex 103 and the surface 108d of the second metal part 108 facing away from the electrode-diaphragm complex 103 are in a common plane.

[0234] The first metal member 102 and the second metal member 108 have a substantially uniform thickness in a range of 150 μm to 350 μm.

[0235] In accordance with Figure 1 In the first embodiment of the energy storage element 100 , the rounded edge 108 a of the second metal piece 108 is bent by 90° and welded to the housing cup 101 at its circumference.

[0236] And according to Figure 2 In the second embodiment of the energy storage element 100, the middle section 101f of the housing cup 101 and the cover closing section 101g are separated from each other by a radial bead 101h, which surrounds the outer side of the housing cup 101 in an annular manner. The second seal 110 arranged in the cover closing section 101g is in pressure contact with the second metal part 108 and the inner side of the housing cup 101 and electrically insulates the two parts from each other. The second seal 110 preferably has a rounded edge 110a.

[0237] Figure 3The third embodiment of the energy storage element 100 shown differs from the first and second embodiments only in that the second metal part 108 is connected to the housing cup 101 via a folding lock. Of course, in this embodiment, the housing is not potential-free, and has an anode potential or a cathode potential depending on the design.

[0238] The preferred structure of the electrode-diaphragm complex is Figure 6 It is concluded that the electrode-diaphragm complex 103 includes a strip-shaped anode 111 having a strip-shaped anode current collector 112 and a strip-shaped cathode 113 having a strip-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. The anode current collector 112 and the cathode current collector 114 have a first longitudinal edge 112a, 114a and a second longitudinal edge, a main area 112b, 114b and a free edge strip 112c, 114c. The main area 112b, 114b is loaded with an electrode material layer (negative electrode material in the case of the anode 111 and positive electrode material in the case of the cathode 113). The free edge strips 112c, 114c extend along the corresponding first longitudinal edges 112a, 114a and are not loaded with electrode material. The two electrodes are displayed separately in an unwound state. In the wound electrode-diaphragm complex 103, the anode 111 and the cathode 113 are arranged offset from each other so that the first longitudinal edge 114a of the cathode current collector 114 emerges from the first end face 103a of the electrode-diaphragm complex 103. The first longitudinal edge 112a of the anode current collector 112 emerges from the second end face 103c of the electrode-diaphragm complex. This can be clearly seen in the illustration at the bottom right. The offset arrangement can be seen from the illustration at the bottom left. There are also two strip-shaped separators 115a and 115b, which separate the electrodes 111 and 113 from each other in the wound body. The wound body side 103b of the electrode-diaphragm complex 103 is formed by a plastic foil in most cases.

[0239] With the help of Figure 5 , a method for manufacturing the energy storage element 100 as described above will be described below.

[0240] In the first step shown under A, as described above, a housing cup 101 with a terminal circular opening 101a and a through hole 101e in the bottom 101b and an electrode-diaphragm complex 103 with a first terminal end face 103a and a second terminal end face 103c are provided. In addition, a first metal part 102 with a cup-shaped protrusion 102a is provided. In step A, the first metal part 102 is also arranged on the first end face 103a and connected by welding to the free edge strip 112c or 114c emerging from the first end face 103a. In addition, in this embodiment of the method, a second metal part 108 is provided and connected by welding to another of these free edge strips 112c or 114c emerging from the second end face 103c.

[0241] In the second step shown under B, the electrode-diaphragm assembly 103 is pushed into the housing cup 101 with the first metal part 102 and preferably the second metal part 108 and with the first end face 103a facing forward through the terminal circular opening 101a of the housing cup 101, so far that the cup-shaped projection 102a protrudes through the through hole 101e of the housing cup bottom 101b. An annular spacer 105 made of an electrically insulating material is arranged on the housing cup bottom 101b or on the metal part 102 to determine the size of the cavity (here the above-mentioned annular gap 106) between the metal part 102 and the bottom 101b. When according to Figure 1 When manufacturing the energy storage element 100 , the circular edge 108 a of the second metal piece is preferably welded to the housing cup 101 around the periphery by means of a laser or the like.

[0242] In the second step shown under C and D, the annular gap 106 between the first metal part 102 and the bottom 101 b is filled with a casting compound which has electrically insulating properties in the cured state and forms the first seal 104. The casting compound is then cured, for example in air and at room temperature, but preferably at 100° C. under vacuum.

[0243] In the third step shown under E, electrolyte is filled into the inner space of the housing cup 101 through the circular opening 108b in the second metal part 108. At this time, the energy storage element 100 is preferably still under vacuum. This can prevent suspended matter from undesirably penetrating into the interior of the housing.

[0244] In the last step shown under F, the circular opening 108b in the second metal part 108 is preferably closed by means of a diaphragm 109, which is designed to rupture under a certain overpressure prevailing inside the housing. To this end, the diaphragm 109 is welded to the second metal part 108 in the recessed area 108c of the second metal part 108 by means of a laser or the like.

[0245] Alternatively, the opening 108b can also be closed by means of a rivet. In this case, the rivet comprises a first flange in the housing, a second flange outside the housing, and a rod guided through the opening to connect the first flange and the second flange. Here, the first flange and the second flange surround the housing part 108 between them. In this case, the recessed area 108c is not required. In a preferred embodiment, an annular seal (for example made of a suitable polymer material) can be arranged between the first flange and the housing part 108 and / or between the second flange and the housing part 108. Alternatively, the first flange and the housing part 108 and / or the second flange and the housing part 108 can also be connected by a weld. This can be, for example, a circular weld guided around the opening 108b.

[0246] It should be understood that Figures 1 to 5 The above-described embodiments of the illustrated specific embodiments are merely preferred design variants of the invention and do not limit the scope of protection of the independent claim 1. Alternative design variants of the invention are apparent to a person skilled in the art from the general part.

[0247] Figure 7 The fourth embodiment of the energy storage element 100 shown differs from the first and second embodiments in that the second metal part 108 is a component of a multi-part cover assembly, which, in addition to the metal part 108, also includes a metal diaphragm 116 and a pole cap 117 as well as an electrically insulating seal 110. The seal 110 isolates the diaphragm 116 from the metal part 108 in the edge region. The center of the diaphragm is preferably connected to the metal part 108 by welding. In the event of an irregular overpressure in the battery cell, the diaphragm 116 can bend outwards, so that the connection with the metal part 108 is disconnected.

[0248] The energy storage element 100 also has a thin lithium layer 118 on the inner side of the housing side. This layer serves as a lithium reservoir and can compensate for lithium ion losses during operation. In addition, the layer can also be used as a reference electrode, because the layer is in direct contact with the housing and is thus in electrical contact. Thus, for example, the voltage drop between the reference electrode and the positive electrode or negative electrode can be determined. By applying a corresponding voltage, the lithium ion concentration in the electrolyte of the energy storage element can also be influenced in a targeted manner.

Claims

1. An energy storage element (100), the energy storage element having the following characteristics: a. The energy storage element (100) comprises an electrode-diaphragm complex (103) having an anode (111) / diaphragm (115a, 115b) / cathode (113) sequence, wherein The anode (111) of the electrode-separator complex (103) is designed to be strip-shaped and comprises a strip-shaped anode current collector (112), wherein the strip-shaped anode current collector has a first longitudinal edge (112a) and a second longitudinal edge parallel to the first longitudinal edge (112a), The anode current collector (112) is in the form of a strip and comprises a main region (112b) loaded with a layer made of a negative electrode material and a free edge strip (112c), the main region being loaded with a layer made of a negative electrode material, the free edge strip extending along a first longitudinal edge (112a) of the anode current collector and not loaded with the negative electrode material, The cathode (113) of the electrode-separator complex (103) is designed to be strip-shaped and comprises a strip-shaped cathode current collector (114), wherein the strip-shaped cathode current collector has a first longitudinal edge (114a) and a second longitudinal edge parallel to the first longitudinal edge (114a), The cathode current collector (114) is in the form of a strip and comprises a main region (114b) loaded with a layer of positive electrode material and a free edge strip (114c), the main region being loaded with a layer of positive electrode material, the free edge strip extending along a first longitudinal edge (114a) of the cathode current collector and not loaded with the positive electrode material, The electrode-separator complex (103) is in the form of a cylindrical wound body, the wound body has a first end face (103a) and a second end face (103c) and a wound body side face (103b) located therebetween, and the electrode-separator complex 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 composite (103) designed as a winding body in such a way that the free edge strip (114c) of the cathode current collector (114) or the free edge strip (112c) of the anode current collector (112) emerges from the first end face (103a), b. The energy storage element (100) comprises a housing sealed against air and liquid, the housing comprising a metal housing cup (101) having a bottom (101b) and a surrounding side wall (101c) as well as an end opening (101a) and a cover (101d), c. the energy storage element (100) comprises a metal piece (102) covering the first end surface (103a), d. The metal member (102) comprises: a flat region (102a), the free edge strip (112c; 114c) emerging from the first end face (103a) being welded to the flat region, wherein the first longitudinal edge (112a; 114a) forms a surface on which the metal part (102) covering the first end face (103a) is at least partially flatly placed or into which the metal part (102) is at least partially pressed, and a projection (102b) pointing away from the first end face (103a), wherein the metal part (102) together with the projection (102b) are formed in one piece, e. The bottom (101b) of the housing cup (101) has a through hole (101e), the protrusion (102b) is pushed into the through hole or the protrusion (102b) protrudes through the through hole, so that the protrusion (102b) can be mechanically contacted from the outside of the housing, and f. The bottom (101b) and the metal member (102) are insulated from each other by an electrically insulating seal (104).

2. The energy storage element (100) according to claim 1, wherein the energy storage element has at least one of the following additional features: a. the protrusion (102b) of the metal member (102) pointing away from the first end face (103a) is designed to be cup-shaped, b. The metal member (102) together with the protrusion (102b) are formed in one piece.

3. The energy storage element (100) according to claim 1 or 2, wherein the energy storage element has at least one of the following additional features: a. the strip-shaped electrodes (111, 113) are formed and / or arranged in the electrode-separator complex (103) designed as a winding body in such a way that one of the free edge strips (112c; 114c) of the anode current collector (112) or the cathode current collector (114) emerges from the first end face (103a) and the other of the free edge strips (112c; 114c) emerges from the second end face (103c) of the electrode-separator complex (103), b. the energy storage element (100) comprises the metal member (102) covering the first end face (103a) as the first metal member (102), c. a second metal piece (108) covers the second end face (103c) and is directly welded to the free edge strips (112c, 114c) emerging from the second end face (103c), d. the second metal member (108) constitutes a cover member (101d) of the housing, e. The second metal piece (108) closes the end opening (101a) of the housing cup (101).

4. The energy storage element (100) according to any one of the preceding claims, having at least one of the following additional features: a. The end opening (101a) of the housing cup (100) is designed to be circular, b. The first metal piece and / or the second metal piece (102; 108) is designed in a disc shape and has a rounded edge (102c; 108a), c. The circular edge (108a) of the second metal member is bent 90°, d. The seal (104) is designed to have a circular edge (104a) and is at least partially disc-shaped or ring-shaped, e. The energy storage element (100) comprises an insulating device (107) made of an electrically insulating material, wherein the insulating device is arranged between the edge (102c) of the metal member (102) covering the first end surface (103a) and the housing cup (101) and electrically insulates the potential of the edge (102c) of the first metal member (102) from that of the housing cup (101).

5. The energy storage element (100) according to any one of the preceding claims, having at least one of the following additional features: a. The housing comprises the bottom (101b), the middle section (101f) and the cover closing section (101g) in axial sequence, b. In the middle section (101f), the winding side (103b) of the electrode-diaphragm assembly (103) designed as a winding contacts the inner side of the housing cup (101), c. The middle section (101f) is designed to be columnar.

6. The energy storage element (100) according to any one of the preceding claims, having at least one of the following additional features: a. the metal part (102) covering the first end surface (103a) has a first side (102d) oriented toward the bottom of the housing cup (101) and a second side (102e) oriented toward the electrode-diaphragm complex, b. an annular spacer (105) made of an electrically insulating material is arranged between the bottom (101b) of the housing cup (101) and the metal member (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), which is filled by the seal (104).

7. The energy storage element (100) according to any one of the preceding claims, having at least one of the following additional features: a. the first longitudinal edge (112a; 114a) along which the free edge strip (112c; 114c) emerges from the first end face (103a) of the electrode-diaphragm assembly (103) extends forms a surface on which the metal part (102) covering the first end face (103a) lies at least partially flat or into which the metal part (102) is at least partially pressed, b. the size of the metal piece (102) covering the first end surface (103a) is determined so that it covers at least 40%, preferably at least 60%, particularly preferably at least 80% of the first end surface (103a), c. the metal piece (103) covering the first end surface (103a) has a preferably uniform thickness, the thickness being 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 surface (103a) is designed to be columnar and appears as a columnar groove on the second side (102e) of the metal part (102) and as a columnar protrusion on the first side (102d) of the metal part (102).

8. The energy storage element (100) according to any one of claims 3 to 7, wherein the energy storage element has at least one of the following additional features: a. the first longitudinal edge (112; 114a) along which the free edge strip (112c; 114c) emerging from the second end face (103c) of the electrode-diaphragm assembly (103) extends forms a surface against which the second metal part (108) at least partially bears flatly or into which the second metal part (108) is at least partially pressed, b. The size of the second metal member (108) is determined so that it covers at least 40%, preferably at least 60%, and particularly preferably at least 80% of the second end face (103c), c. The second metal piece (108) has a preferably uniform thickness in the range of 50 μm to 600 μm, preferably in the range of 150 μm to 350 μm.

9. The energy storage element (100) according to claim 5, wherein the energy storage element has at least one of the following additional features: a. the intermediate section (101f) and the cover closing section (101g) are separated from each other by a radial bead (101h), which surrounds the outer side of the housing cup (101) in an annular manner, b. the energy storage element (101) comprises the seal (104) as a first seal (104) which electrically insulates the bottom of the housing cup and the first metal member from each other, c. a second seal (110) is arranged in the cover closing section (101g), the second seal being in pressure contact with the second metal part (108) and the inner side of the housing cup (101), d. The second sealing member (110) is designed to be annular and has a circular edge (110a).

10. The energy storage element (100) according to any one of the preceding claims, having at least one of the following additional features: a. the energy storage element (100) has a safety device against internal overpressure in the cover closing section (101g), b. the second metal member (108) has an opening (108b) and a recessed area (108c) surrounding the opening (108b), and the thickness of the recessed area is reduced compared to the rest of the second metal member (108), c. The opening (108b) of the second metal member (108) is designed to be circular, d. the opening (108b) of the second metal part (108) is closed by a diaphragm (109) which is designed to rupture under a certain overpressure prevailing inside the housing, e. the diaphragm (109) enters the recessed area (108c) of the second metal member (108), f. A surface (109a) of the diaphragm (109) facing away from the electrode-diaphragm assembly (103) and a surface (108d) of the second metal part (108) facing away from the electrode-diaphragm assembly extend in a common plane.

11. A method for producing an energy storage element (100) having one or more of the features of claims 1 to 10, the method comprising the following steps: a. providing a housing cup (101) having an end opening (101a) and a through hole (101e) in the bottom (101b) and an electrode-diaphragm complex (103) having a first end face and a second end face (103a, 103c) as defined in claim 1, b. providing a metal member (102), the metal member comprising a protrusion (102b), c. arranging the metal piece (102) on the first end surface (103a) and connecting it to the free edge strip (112c; 114c) emerging from the first end surface (103a) by welding, d. pushing the electrode-diaphragm assembly (103) together with the metal part (102) and with the first end face (103a) facing forward through the end opening (101a) of the housing cup (101) into the housing cup (101) until the projection (102b) is pushed into the through hole (101e) or protrudes through the through hole (101e), e. Filling the cavity between the metal member (102) and the bottom (101b) with a casting material having electrical insulating properties in a solidified state.

12. The method according to claim 11, wherein the method has at least one of the following additional features: a. prior to step c. as claimed in claim 11, at least one spacer (105) made of an electrically insulating material is arranged on the bottom (101b) of the housing cup (101) or on the metal part (102) to determine the size of the cavity between the metal part (102) and the bottom (101b), b. The spacer (105) is designed to be disk-shaped or ring-shaped.

13. The method according to claim 11 or claim 12, wherein the method has at least one of the following additional features: a. pushing the electrode-diaphragm complex (103) into the housing cup (101), wherein the strip-shaped electrode (111; 113) is formed and / or arranged so that one of the free edge strips (112c; 114c) of the anode current collector (112) or the cathode current collector (114) emerges from the first end face (103a) and the other of the free edge strips (112c; 114c) emerges from the second end face (103c) of the electrode-diaphragm complex (103), b. the energy storage element (100) comprises the metal member (102) covering the first end face (103a) as the first metal member (102), c. before or after the electrode-diaphragm assembly (103) is pushed into the housing cup (101), a second metal part (108) is arranged on the second end face (103c) and connected there by welding to the free edge strip (112c; 114c) emerging from the second end face (103c), d. The edge (108a) of the second metal piece (108) is welded to the housing cup (101) at its periphery.

14. The method according to any one of claims 11 to 13, wherein the method has at least one of the following additional features: a. filling the inner space of the housing cup (101) with electrolyte through the opening (108b) in the second metal member (108), b. the opening (108b) in the second metal part (108) is closed, in particular, by means of a diaphragm (109), which is designed to rupture under a certain overpressure prevailing in the interior of the housing, c. The opening (108b) is designed to be circular.

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