Energy storage cell and method for producing such an energy storage cell

Abstract

The invention relates to an energy storage cell (100), in which a free edge strip (109a) of a cathode current collector (109) is welded to a contact element (112) of a cover assembly (102). The invention further relates to a method for producing such an energy storage cell.

Description

Technical Field

[0001] The invention described below relates to an energy storage battery cell and a method of manufacturing the same. Background Art

[0002] 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 inside the cell. This ion flow passes through the diaphragm and is realized by an ion-conducting electrolyte.

[0003] 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.

[0004] Nowadays, for many applications, secondary lithium-ion battery cells are used as energy storage elements, since 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.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] As electrolyte, lithium-ion battery cells usually include a solution of a lithium salt, such as lithium hexafluorophosphate (LiPF6), in an organic solvent such as ethers and carbonates.

[0009] 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.

[0010] In many embodiments, the electrode-separator complex is designed in the form of a jelly roll or is processed into a jelly roll. 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 winder and spirally wound into a jelly roll of the sequence positive electrode / separator / negative electrode in the winder. 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. Subsequently, in a further step, the complex is rolled up.

[0011] 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.

[0012] 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.

[0013] A cylindrical round battery cell is described in WO 2017 / 215900 A1, 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 extends from one side of the winding body, and the longitudinal edge of the current collector of the negative electrode extends 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 the 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. Summary of the invention

[0014] Based on this prior art, it is desirable to further increase the energy density of energy storage battery cells, in particular energy storage battery cells of the type described in WO 2017 / 215900 A1.

[0015] This object is achieved by an energy storage cell having the features of claim 1. The invention also provides a production method having the features of claim 10. Preferred embodiments of the invention are given in the dependent claims.

[0016] Battery cell of the present invention

[0017] The energy storage cell according to the invention always has the following features a. to l.:

[0018] a. A battery cell comprises an electrode-separator complex having an anode / separator / cathode sequence.

[0019] b. The anode of the electrode-separator complex is designed in a strip shape and includes a strip-shaped anode current collector having a first longitudinal edge and a second longitudinal edge parallel thereto.

[0020] c. The strip-shaped anode current collector comprises 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.

[0021] d. The cathode of the electrode-separator complex is designed in a strip shape and includes a strip-shaped cathode current collector having a first longitudinal edge and a second longitudinal edge parallel thereto.

[0022] e. The cathode current collector in the form of a strip comprises a main area 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.

[0023] f. 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 includes an anode and a cathode in a spirally wound form.

[0024] g. The strip-shaped electrode is formed and / or arranged in an electrode-separator assembly designed as a jellyroll in such a way that a free edge strip of the anode current collector or a free edge strip of the cathode current collector protrudes from the first end face.

[0025] h. The battery cell comprises a housing sealed against gas and liquid, which encloses an inner space in which the electrode-diaphragm assembly is arranged, and has a metal housing cup with a circular opening at the end and a cover assembly with a circular edge that closes the circular opening.

[0026] i. The cover assembly includes an annular seal made of an electrically insulating material, the annular seal surrounding a circular edge of the cover assembly.

[0027] j. The housing cup comprises a bottom, a middle section and a closed section in axial order, wherein

[0028] The middle section is designed as a column, and in the middle section, the jellyroll side of the electrode-separator assembly designed as a jellyroll is in contact with the inner side of the housing cup, and

[0029] • In the closed section, the annular seal is in pressure contact with the cover assembly and the inside of the housing cup.

[0030] k. The cover assembly includes, from the inside to the outside: a metal contact element; a metal diaphragm that is electrically connected to the metal contact element and bulges or bursts outward from a defined overpressure in the housing; and a metal pole cap that is electrically connected to the metal diaphragm.

[0031] The unique features of the energy storage battery cell according to the present invention are:

[0032] 1. The free edge strip extending from the first end face of the electrode-diaphragm assembly is welded to the contact element of the cover assembly.

[0033] The free edge strip extending from the first end face may be a free edge strip of the cathode current collector or a free edge strip of the anode current collector. Preferably, it is a free edge strip of the cathode current collector.

[0034] Unlike WO 2017 / 215900 A1, the energy storage battery cell according to the present invention has a contact element, which is part of the cover assembly. Correspondingly, no separate electrical conductor is required between the cover and the contact element. Therefore, the energy storage battery cell according to the present invention is easy to manufacture. The omission of a separate conductor also makes it possible to reduce the internal resistance of the energy storage battery cell and provide more available volume in the housing, thereby allowing more active material to be introduced into the housing to increase the energy density.

[0035] Connect one of the electrodes to the housing cup

[0036] One of the electrodes of the energy storage element according to the present invention is electrically connected to the cover assembly via a free edge strip extending from the first end face, while another of the electrodes is preferably electrically connected to the housing cup. Correspondingly, the uniqueness of the energy storage element according to the present invention is preferably at least one of the following immediately mentioned features:

[0037] a. Strip-shaped electrodes are formed and / or arranged in an electrode-diaphragm assembly designed as a winding body in such a way that one of the free edge strips of the anode current collector and the cathode current collector extends from a first end face and the other of the free edge strips extends from a second end face of the electrode-diaphragm assembly.

[0038] b. Another of these free edge strips extending from the second end face of the electrode-diaphragm complex is electrically connected to the bottom of the housing cup.

[0039] Here, it also applies that the free edge strip extending from the first end face is preferably a free edge strip of the cathode current collector. Correspondingly, the edge strip extending from the second end face is preferably a free edge strip of the anode current collector.

[0040] Particularly preferably, the free edge strip protruding from the second end face is welded to the bottom of the housing cup.

[0041] Alternatively, however, the edge strip can also be electrically connected to the bottom of the housing cup via a separate electrical conductor, for example a plate-shaped conductor. This separate electrical conductor can be made, for example, of nickel or copper or titanium or a nickel alloy or a copper alloy or a titanium alloy or a stainless steel (such as type 1.4303 or 1.4404 or type SUS304) or nickel-plated copper, especially when the edge strip extending from the second end face is a free edge strip of the anode current collector.

[0042] Preferred structure of cover assembly

[0043] The cover assembly is installed in each case in preassembled form. In a preferred embodiment, the cover assembly is characterized by at least one of the following features a. to f.:

[0044] a. The diaphragm is in direct contact with the contact element and is connected to it by welding.

[0045] b. The diaphragm is designed to be circular and therefore has rounded edges.

[0046] c. The contact element is designed to be circular and therefore has rounded edges.

[0047] d. The contact element is welded to the center of the diaphragm.

[0048] e. The contact element and the diaphragm have approximately the same diameter.

[0049] f. The diaphragm and the contact element are in electrical contact with each other only via the welding area in the center of the diaphragm.

[0050] It is preferred that the features a. and b. and d. and f. just mentioned above are implemented in combination. It is preferred that all six features a. to f. just mentioned above are implemented in combination.

[0051] Preferably, the diaphragm is in direct contact with the pole cap. In a particularly preferred embodiment, the diaphragm is connected to the pole cap by welding.

[0052] Preferably, a pole cap terminates the cover assembly outwardly.

[0053] In a further preferred embodiment, the lid assembly is distinguished by at least one of the following features a. to f.:

[0054] a. The annular seal surrounds the circular edge of the metal contact element.

[0055] b. The annular seal surrounds the circular edge of the metal diaphragm.

[0056] c. An annular seal separates the circular edge of the metal diaphragm from the circular edge of the metal contact element.

[0057] It is preferred that the features a. and b. and c. just mentioned above are implemented in combination.

[0058] In a preferred embodiment of the energy storage cell according to the invention, the annular seal has several functions. On the one hand, the annular seal electrically separates the cover assembly from the metal housing cup and simultaneously seals the housing. On the other hand, the annular seal electrically separates the metal contact element from the metal diaphragm. For this purpose, the annular seal can, for example, have an F or E-shaped cross section, as will be explained further with reference to the figures.

[0059] Preferred design of the free edge strip extending from the first end face

[0060] Preferably, the energy storage battery cell according to the present invention is characterized by at least one of the following features a. and b.:

[0061] a. The intermediate section and the closing section are separated from one another by a radial recess which annularly surrounds the outside of the housing cup.

[0062] b. The free edge strip extending from the first end face is wider than the distance d between the middle section and the closed section, so that the edge strip spans the distance d and is in direct contact with the contact element.

[0063] c. The distance d is defined by the upper and lower edges of the recess of the housing cup.

[0064] It is preferred that the features a. and b. just mentioned above, preferably the features a. to c. just mentioned above, are implemented in combination.

[0065] Particularly preferably, the energy storage cell according to the invention is distinguished by at least one of the following features a. and b.:

[0066] a. The housing cup has the same maximum outer diameter in the middle section and the closed section.

[0067] b. In the region of the depression, the outer diameter of the housing cup is reduced by 4 to 20 times the wall thickness of the housing cup in this region.

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

[0069] According to the above embodiment, the housing cup includes a recessed section between the middle section and the closed section, in which the diameter of the housing cup decreases from a maximum value to a minimum value in the axial direction and then increases again to a maximum value.

[0070] Preferably, the energy storage battery cell according to the present invention is characterized by at least one of the following features a. and b.:

[0071] a. The free edge strip extending from the first end face of the electrode-diaphragm assembly is pressed inwardly in the recessed area of ​​the housing cup toward the center of the housing cup.

[0072] b. In the region of the depression, an electrically insulating material is arranged between the inner side of the housing cup and the free edge strip, which electrically insulates the free edge strip from the electrical potential of the housing cup.

[0073] It is preferred that the features a. and b. just mentioned above are implemented in combination.

[0074] Preferred shell shape

[0075] The energy storage battery cell 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.

[0076] The housing cup of the energy storage cell according to the invention is usually formed by deep drawing. However, it is also possible to form the cup by welding the bottom into the tubular half.

[0077] Preferably, the height of the energy storage battery cell according to the invention, which is designed as a cylindrical round battery 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 battery cells with these shape parameters are particularly suitable for providing power for electric drives of motor vehicles.

[0078] As described above, in the battery cell according to the invention, the jellyroll side of the electrode-separator assembly designed as a jellyroll is in contact with the inner side of the housing cup in the middle section. Particularly preferably, the assembly directly adjoins the inner side of the housing cup. In some embodiments, it can be provided that the inner side is electrically insulated, for example, by means of a foil. In this case, the jellyroll side of the electrode-separator assembly is in contact with or rests against the foil-lined inner side of the housing cup.

[0079] Particularly preferably, the housing cup has an opening edge in the closed section defining a circular opening, which is bent radially inward beyond the edge of the cover component surrounded by the seal and fixes the cover component including the seal in the circular opening of the housing cup in a form-fitting manner.

[0080] Preferably, the annular seal is present in a compressed form in the closing section. The annular seal is preferably pressed from the inside of the housing cup toward the edge of the cover assembly.

[0081] Preferred material properties for current collector, housing cup and lid assembly

[0082] The current collector of the energy storage battery cell according to the present invention is used to establish electrical contact with the electrochemically active components contained in the corresponding electrode material over the largest possible area. Preferably, the current collector is made of metal or is metallized at least on the surface.

[0083] In the case of energy storage cells designed as lithium-ion battery cells according to the invention, copper or nickel or other conductive materials (especially copper alloys and nickel alloys or metals coated with nickel) are suitable as metals for 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, such as 1.4303 or 1.4404 type or SUS304 type stainless steels, can also be considered.

[0084] In the case of energy storage cells according to the invention designed as lithium-ion cells, in particular aluminum or other electrically conductive materials (including also aluminum alloys) are suitable as metals for the cathode current collector.

[0085] 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%.

[0086] 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.

[0087] 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.

[0088] The current collector is preferably loaded with the corresponding electrode material on both sides.

[0089] 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%.

[0090] The nature of the metal component of the cap assembly generally depends on whether the free edge strip extending 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.

[0091] If the free edge strip extending from the first end face is the free edge strip of the cathode current collector, it is preferred that the metal contact element and preferably also the metal diaphragm are made of the same or chemically similar material as the cathode current collector, i.e., in particular made of aluminum or aluminum alloy.

[0092] If the free edge strip extending from the first end face is the free edge strip of the anode current collector, it is preferred that the metal contact element and preferably also the metal diaphragm are made of the same or chemically similar material as the anode current collector, i.e., in particular made of copper or nickel, or copper alloy or nickel alloy, or stainless steel.

[0093] For example, the pole cap is made of nickel-plated steel or aluminum or aluminum alloy.

[0094] The annular 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).

[0095] Electrodes and electrode materials

[0096] In a particularly preferred embodiment, the energy storage battery cell according to the invention is a lithium-ion battery cell.

[0097] Basically all electrode materials known for secondary lithium-ion battery cells can be used for the electrodes of the energy storage battery cell.

[0098] 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 particulate form) can be used as the active material. Alternatively or additionally, lithium titanate (Li4Ti5O 12 ) or its derivatives (preferably also in particulate form) 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, antimony or compounds or alloys of these materials capable of reversibly embedding and de-embedding lithium (such as silicon oxide (especially SiO 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 exceeds that of graphite or similar materials many times. Usually, a mixture of silicon-based and carbon-based storage materials is used. In addition, a thin anode made of metallic lithium is also suitable.

[0099] 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, the general formula is LiNi x Mn y Coz O2 (where x+y+z is usually 1) lithium nickel manganese cobalt oxide (NMC), lithium manganese spinel (LMO) with the general formula LiMn2O4 or lithium nickel manganese cobalt oxide (NMC) with the general formula LiNi x Co y Al z Lithium nickel cobalt aluminum oxide (NCA) of O2 (where x+y+z is usually 1) is particularly suitable. Its derivatives can also be used, such as those 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 Lithium nickel manganese cobalt aluminum oxide (NMCA) of the MO compound and / or mixtures of the above materials. The cathode active material is preferably also used in particulate form.

[0100] In addition, the electrode of the energy storage battery cell according to the present invention preferably contains 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 adjacent particles in the matrix are preferably in direct contact. The conductive agent is used to improve the conductivity of the electrode. Common electrode binders are based on polyvinylidene fluoride (PVDF), polyacrylate (lithium), styrene-butadiene rubber or carboxymethyl cellulose or a mixture of different binders. Common conductive agents include carbon black, fine graphite, carbon fiber, carbon nanotubes and metal powders.

[0101] Preferred material embodiments for electrolyte and separator

[0102] The energy storage cell according to the invention preferably comprises a liquid electrolyte, in the case of a lithium-ion cell, 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).

[0103] The separator of the electrode-separator complex of the energy storage battery cell according to the invention is preferably designed in the form of a strip, just like the electrode. If necessary, the electrode-separator complex of the energy storage battery cell according to the invention comprises 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.

[0104] The diaphragm is preferably formed by an electrically insulating plastic foil. The diaphragm 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 diaphragms. Preferably, a diaphragm with a thickness in the range of 5 μm to 50 μm is used.

[0105] However, it is also possible that the strip diaphragm is 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).

[0106] Preferred shapes and sizes of electrodes and separators

[0107] The anode current collector, the cathode current collector and the separator or separators of the battery cell according to the invention preferably each have the following dimensions:

[0108] - Length in the range of 0.5m to 25m;

[0109] -Widths in the range of 40mm to 145mm.

[0110] In an electrode-separator complex designed as a jellyroll, the strip-shaped anode, the strip-shaped cathode and the strip-shaped separator(s) are preferably present in a spirally wound form. In order to produce the electrode-separator complex, the strip-shaped electrode is preferably supplied to a winding device together with the strip-shaped separator(s) and is preferably spirally wound around a winding axis in the winding device. In some embodiments, for this purpose, the electrode and the separator are wound on a cylindrical or hollow cylindrical jellyroll core, which is sleeved on a winding mandrel and remains in the jellyroll after winding.

[0111] 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.

[0112] Preferably, the longitudinal edge or edges of the separator form the end faces of the electrode-separator assembly designed as a coil.

[0113] It is also preferred that the free edge strip of the anode current collector or cathode current collector extending from the first end face of the electrode-separator assembly has a maximum protrusion distance in the range of 10 mm to 15 mm, preferably 5 mm to 15 mm, further preferably 5 mm to 10 mm, further preferably 3 mm to 10 mm, particularly preferably 3 mm to 8 mm. The protrusion distance corresponds approximately to the width of the edge strip and the distance d between the middle section and the closed section.

[0114] It is also preferred that the free edge strip of the anode current collector or cathode current collector extending from the second end face of the electrode-separator assembly has a maximum protrusion distance in the range of 1 mm to 5 mm.

[0115] 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 protrudes from one of the end faces and the free edge strip of the cathode current collector protrudes from the other of the end faces.

[0116] Preferred rated capacity of energy storage battery cells

[0117] The rated capacity of the energy storage battery cell 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 battery cell with a 21×70 shape parameter preferably has a rated capacity in the range of 1500 mAh to 7000 mAh, particularly preferably in the range of 3000 to 5500 mAh. In the embodiment as a lithium ion battery cell, the battery cell with an 18×65 shape parameter preferably has a rated capacity in the range of 1000 mAh to 5000 mAh, particularly preferably in the range of 2000 to 4000 mAh.

[0118] 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.

[0119] Preferred embodiments of the contact element

[0120] Covering the end faces of the electrode-diaphragm assembly over the largest possible area and thus connecting the current collector well is of great importance for the current carrying capacity and thermal management of the energy storage cell according to the invention. The greater the coverage, the more likely it is that the longitudinal edge of the respective current collector will be contacted over its entire length. As a result, the heat generated in the electrode-diaphragm assembly during charging or discharging can be dissipated well via the contact element or the bottom of the housing cup.

[0121] Preferably, the energy storage battery cell according to the invention is distinguished by at least one of the following features a. to h.:

[0122] a. The longitudinal edge along which the free edge strip extending from the first end face of the electrode-diaphragm assembly extends forms the surface on which the contact element lies flat or into which the contact element is pressed.

[0123] b. The contact element is dimensioned such that it covers at least 40%, preferably at least 60%, particularly preferably at least 80% of the first end face.

[0124] c. The contact element is a disc or a polygonal plate.

[0125] d. The contact element has at least one through-opening, in particular at least one hole and / or at least one groove.

[0126] e. The contact element has a preferably uniform thickness in the range of 50 μm to 600 μm, preferably in the range of 150 μm to 350 μm.

[0127] f. The contact element has two mutually opposite planar sides and extends substantially in only one dimension.

[0128] g. The contact element has at least one bead which appears as an elongated groove on one planar side of the contact element and as an elongated protrusion on the opposite planar side, wherein the contact element is pressed into the surface formed by the longitudinal edge with the planar side having the elongated protrusion.

[0129] h. In the region of the bead, the contact element is welded to the longitudinal edge of the respective current collector, in particular via one or more weld seams arranged in the bead.

[0130] It is particularly preferred that the features a. to d. just mentioned above are implemented in combination with one another. It is particularly preferred that all features a. to h. are implemented in combination with one another.

[0131] In some embodiments, it has proven to be advantageous to subject the longitudinal edge of the current collector protruding from the first end face to a pretreatment before the contact element is fitted. In particular, at least one groove can be folded into the longitudinal edge, which corresponds to the at least one bead or elongated projection of the flat side of the contact element facing the first end face.

[0132] The longitudinal edge of the current collector can also be subjected to directional deformation by pretreatment, for example, the longitudinal edge can be bent in a defined direction.

[0133] The at least one through-hole in the contact element can, for example, facilitate the ability to immerse the electrode-separator assembly with electrolyte. Furthermore, the pressure generated in the interior of the battery cell can act on the membrane via the through-hole.

[0134] Preferred Embodiments of the Pole Cap

[0135] Preferably, the energy storage battery cell according to the present invention is characterized by the following immediately mentioned feature a.:

[0136] a. One or more openings are formed in the center and / or edge of the polar cap.

[0137] Manufacturing method

[0138] The method according to the invention is used to manufacture an energy storage battery cell, which comprises a housing sealed against gas and liquid, which encloses an inner space in which the electrode-diaphragm complex is arranged, wherein the housing comprises a metal housing cup with a circular opening at the end and a cover assembly with a circular edge that closes the circular opening. For the preferred characteristics of the housing and the cover assembly, reference is made to the above-mentioned embodiments.

[0139] In a preferred embodiment, the method is used to manufacture the above energy storage battery cell.

[0140] The method is unique in that the following features a. to e. are mentioned immediately below:

[0141] a. Providing a housing cup having a circular opening and an electrode-diaphragm complex having a first end surface and a second end surface as defined in claim 1.

[0142] b. Push the electrode-diaphragm assembly with the second end facing forward through the circular opening of the housing cup into the housing cup.

[0143] c. Before or after step b., a metal contact element, in particular the above-mentioned contact element, is arranged on the first end face and fixed by welding.

[0144] d. Before or after step b., attaching a membrane and a pole cap, in particular the above-mentioned membrane and pole cap, to the contact element successively or as a preassembled assembly to form a cover assembly.

[0145] e. Before or after step b., but in any case after step d., forming a weld between the membrane and the contact element.

[0146] Preferably, before step d., but if necessary also after step d., electrolyte is metered into the housing cup.

[0147] Preferably, the housing is closed in step f., thereby forming the radial recess described above in conjunction with the energy storage battery cell according to the invention.

[0148] In principle, step e. can also be carried out only after the closing in step f. is complete. However, step e. is preferably carried out before step f.

[0149] The housing is preferably closed by radially bending an opening edge defining the circular opening beyond an edge of the cover assembly surrounded by the seal, so that the cover assembly together with the seal is fixed in the circular opening of the housing cup in a form-fitting manner.

[0150] Preferably, radial depressions are introduced so that axial pressure can be exerted on the battery cell housing from above when bending the opening edge.

[0151] In a further preferred embodiment, the radial depressions are formed as described in FIGS. 8A to 8C of EP 3916877 A1.

[0152] In a preferred embodiment, before or after step b., a diaphragm, annular seal and pole cap, in particular the diaphragm, seal and pole cap described above in conjunction with the battery cell according to the invention, are arranged on the contact element successively or as a preassembled component to form a cover assembly.

[0153] The current collector protruding from the second end face of the electrode-separator assembly can be fixed to the bottom of the housing cup, for example, by means of welding through the bottom.

[0154] In a particularly preferred embodiment, within the scope of the method, the height of the battery cell to be manufactured is calibrated in a further step g. This can be carried out in particular within the scope of the closing process (step f.) or immediately after the closing process. In this regard, the protrusion of the free edge strip of the anode current collector or cathode current collector that protrudes from the first end face of the electrode-diaphragm complex is of great significance, since this protrusion can be deformed due to axial pressure. Thus, for example, after step f., the height of the battery cell can be calibrated by axial pressure on the cover side of the battery cell. In this case, the protrusion can be bent. This can be achieved in particular when the above-mentioned electrically insulating material electrically insulates the protrusion from the potential of the housing cup in the recessed area (see also claim 6, feature b.). BRIEF DESCRIPTION OF THE DRAWINGS

[0155] 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.

[0156] Schematically in the accompanying drawings:

[0157] Figure 1 An embodiment of an energy storage battery cell according to the present invention is shown in a cross-sectional general view;

[0158] Figure 2 An embodiment of an energy storage cell according to the invention is shown in a cross-sectional detail view;

[0159] Figure 3 An embodiment of an energy storage cell according to the invention is shown in a cross-sectional detail view, showing a laser beam directed through an opening in the pole cap to a weld point between a membrane and a contact element; and

[0160] Figure 4 An electrode-separator assembly and its components are shown, which is a constituent part of an energy storage cell according to the invention. DETAILED DESCRIPTION

[0161] Figure 1 and Figure 2 An energy storage cell 100 according to the invention is shown, which has a housing sealed against gas and liquid, comprising a metal housing cup 101 with a circular opening at the end and a cover assembly 102 with a circular edge 102a closing the circular opening.

[0162] The cover assembly 102 further comprises an annular seal 103 made of an electrically insulating material, which surrounds the circular edge 102a of the cover assembly and electrically insulates the housing cup 101 and the metal parts of the cover assembly 102 from each other.

[0163] The housing cup 101 includes a bottom 101a, a middle section 101b and a closed section 101c in axial order, wherein the middle section 101b is designed to be cylindrical. In the middle section 101b, the winding body side 104c of the electrode-diaphragm composite 104 designed as a winding body is in contact with the inner side of the housing cup 101. In the closed section 101c, the annular seal 103 is in pressure contact with the cover component 102 and the inner side of the housing cup 101. The housing cup 101 has an opening edge 101d defining a circular opening in the closed section 101c, which is radially bent inward beyond the edge 102a of the cover component 102 surrounded by the seal 103, and the opening edge fixes the cover component 102 including the seal 103 in the circular opening of the housing cup 101 in a form-fitting manner. The center section 101 c and the closing section 101 d are separated from one another by a radial recess 101 e which surrounds the outer side of the housing cup 101 in an annular manner.

[0164] The cover assembly 102 of the present embodiment comprises, from the inside to the outside, a disc-shaped contact element 112, a circular metal diaphragm 114 which bulges or bursts outwards from a defined overpressure in the housing, and a pole cap 117. The contact element 112 is welded to the diaphragm 114, which is in turn welded to the pole cap 117, which terminates the cover assembly 102 outwards. If the diaphragm 114 bulges outwards due to an overpressure which can act directly on the diaphragm 114 via a through hole in the contact element, which is not shown, the electrical contact between the contact element 112 and the diaphragm 114 or the pole cap 117 is disconnected. In the case of very high pressures, the diaphragm 114 can also burst.

[0165] The electrode-diaphragm composite 104 has a first end face 104a and a second end face 104b and a winding body side face 104c located therebetween. Figure 4. The electrode-diaphragm complex comprises a strip-shaped anode 105 having a strip-shaped anode current collector 106 and a strip-shaped cathode 108 having a strip-shaped cathode current collector 109. The anode current collector 106 is preferably a foil made of copper or nickel. The cathode current collector 109 is preferably an aluminum foil. The anode current collector 106 and the cathode current collector 109 have a first longitudinal edge 106a, 109a and a second longitudinal edge, a main region 106b, 109b and a free edge strip 106c, 109c. The main regions 106b, 109b are loaded with an electrode material layer (negative electrode material in the case of an anode and positive electrode material in the case of a cathode). The free edge strips 106c, 109c extend along the corresponding first longitudinal edges and are not loaded with electrode material. The two electrodes are shown separately in an unwound state. In the wound electrode-diaphragm complex 104, the anode and cathode are arranged offset from each other so that the first longitudinal edge 109a of the cathode current collector 109 protrudes from the first end face 104a of the electrode-diaphragm complex 104. The first longitudinal edge 106a of the anode current collector 106 protrudes from the second end face 104b of the electrode-diaphragm complex 104. 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 111a and 111b, which separate the electrodes 105 and 108 from each other in the wound body. The side 104c of the wound body is usually composed of a plastic foil.

[0166] Back to Figure 1 and Figure 2 Here, the free edge strip 109c is welded to the contact element 112 via the first longitudinal edge 109a of the cathode current collector 109, and is preferably in direct contact with the contact element 112 over its entire length. The contact element covers the first end face 104a of the electrode-diaphragm assembly 104 and is flatly placed on the first longitudinal edge 109a of the cathode current collector 109. The first longitudinal edge 106a of the anode current collector 106 is directly welded to the bottom 101a of the housing, and is preferably in direct contact with the bottom 101a over its entire length.

[0167] In such a structure of the energy storage cell 100 , a separate conductor connecting the contact element 112 to the cover assembly can be omitted.

[0168] The middle section 101b and the closed section 101c are separated from each other by a radial recess 101e which annularly surrounds the outside of the housing cup 101. The free edge strip 109c protruding from the first end face 104a is wider than the distance d between the middle section 101b and the closed section 101c, so that the edge strip 109c spans the distance d and is in direct contact with the contact element 112. The distance d is defined by the upper edge 101f and the lower edge 101g, which mark the beginning and the end of the recess 101e.

[0169] Since the electrode-separator complex 104 designed as a winding is wider than the available space in the region of the recess 101e, the free edge strip 109c of the cathode current collector 109 is pressed inwardly in the region of the recess 101e toward the center of the housing cup 101. In order to prevent short circuits, an electrically insulating material 115 is applied to the inner side of the recess 101e, which electrically insulates the free edge strip 109c of the cathode current collector 109 from the potential of the housing cup 101.

[0170] The energy storage cell 100 typically has a height in the range of 60 mm to 120 mm, and its diameter is preferably in the range of 20 mm to 50 mm. The housing cup 101 typically has a wall thickness in the range of 0.1 mm to 0.3 mm in the middle section 101 b.

[0171] Figure 3 The energy storage battery cell 100 is shown in FIG. Figure 1 and Figure 2 The illustration of the energy storage cell in FIG. 1 differs only in that a laser beam 119 is shown which is directed through an opening 117 a in a pole cap 117 in order to form a weld between the contact element 112 and the diaphragm 114 .

Claims

1. An energy storage battery cell (100), the energy storage battery cell having the following characteristics: a. The battery cell (100) comprises an electrode-diaphragm complex (104) having an anode (105) / diaphragm (111a, 111b) / cathode (108) sequence, b. the anode (105) of the electrode-separator complex (104) is designed to be strip-shaped and comprises a strip-shaped anode current collector (106), wherein the strip-shaped anode current collector has a first longitudinal edge (106a) and a second longitudinal edge parallel thereto, c. the anode current collector (106) being in the form of a strip comprises a main region (106b) loaded with a layer made of a negative electrode material (107) and a free edge strip (106c), the main region being loaded with a layer made of a negative electrode material (107), the free edge strip extending along a first longitudinal edge (106a) of the anode current collector and not loaded with the negative electrode material, d. The cathode (108) of the electrode-separator complex (104) is designed to be strip-shaped and includes a strip-shaped cathode current collector (109), wherein the strip-shaped cathode current collector has a first longitudinal edge (109a) and a second longitudinal edge parallel thereto, e. the cathode current collector (109) being in strip form comprises a main region (109b) loaded with a layer made of a positive electrode material (110) and a free edge strip (109c), the main region being loaded with a layer made of a positive electrode material (110), the free edge strip extending along a first longitudinal edge (109a) of the cathode current collector and not loaded with the positive electrode material (110), f. the electrode-separator complex (104) is in the form of a cylindrical wound body, the wound body has a first end face (104a) and a second end face (104b) and a wound body side face (104c) located therebetween, and the electrode-separator complex comprises the anode (105) and the cathode (108) in a spirally wound form, g. the anode (105) and the cathode (108) are formed and / or arranged in the electrode-separator assembly (104) designed as a winding body so that the free edge strip (109c) of the cathode current collector (109) or the free edge strip (106c) of the anode current collector (106) protrudes from the first end face (104a), h. The battery cell (100) comprises a housing sealed against gas and liquid, the housing enclosing an inner space in which the electrode-diaphragm assembly (104) is arranged, and the housing has a metal housing cup (101) with a circular opening at the end and a cover assembly (102) with a circular edge (102a) closing the circular opening, i. the cover assembly (102) comprises an annular seal (103) made of an electrically insulating material, the annular seal surrounding the circular edge (102a) of the cover assembly, j. The housing cup (101) comprises, in axial order, a bottom (101a), an intermediate section (101b) and a closed section (101c), wherein The middle section (101b) is designed to be cylindrical, and in the middle section (101b), the winding body side (104c) of the electrode-diaphragm composite (104) designed as a winding body is in contact with the inner side of the housing cup (101), and In the closed section (101c), the annular seal (103) is in pressure contact with the cover assembly (102) and the inside of the housing cup (101), and k. The cover assembly (102) comprises from the inside to the outside: a metal contact element (112); a metal diaphragm (114) electrically connected to the contact element (112) and bulging or bursting outward from a defined overpressure in the housing; and a metal pole cap (117) electrically connected to the metal diaphragm (114), It is characterized in that 1. The free edge strip (106c or 109c) extending from the first end face (104a) is welded to the contact element (112) of the cover assembly (102).

2. The energy storage battery cell according to claim 1, wherein the energy storage battery cell has at least one of the following additional features: a. the strip-shaped electrodes (105, 108) are formed and / or arranged in the electrode-separator assembly (104) designed as a winding body so that one of the free edge strips (106c, 109c) of the anode current collector and the cathode current collector protrudes from the first end face (104a) and the other of the free edge strips protrudes from the second end face (104b) of the electrode-separator assembly (104), b. The other of the free edge strips extending from the second end face (104b) of the electrode-diaphragm complex (104) is electrically connected to the bottom (101a) of the housing cup (101).

3. The energy storage battery cell according to any one of the preceding claims, wherein the energy storage battery cell has at least one of the following additional features: a. the diaphragm (114) is in direct contact with the contact element (112) and is connected thereto by welding, b. the diaphragm (114) is designed to be circular and therefore has rounded edges, c. the contact element (112) is designed to be circular and therefore has rounded edges, d. the contact element (112) is welded to the center of the diaphragm (114), e. the contact element (112) and the diaphragm (114) have substantially the same diameter, f. The diaphragm (114) and the contact element (112) are in electrical contact with each other only via a welding area at the center of the diaphragm (114).

4. The energy storage battery cell according to any one of the preceding claims, wherein the energy storage battery cell has at least one of the following additional features: a. the annular seal (103) surrounds the circular edge of the contact element (112), b. the annular seal (103) surrounds the circular edge of the diaphragm (114), c. The annular seal (103) separates the circular edge of the diaphragm (114) from the circular edge of the contact element (112).

5. The energy storage battery cell according to any one of the preceding claims, wherein the energy storage battery cell has at least one of the following additional features: a. the intermediate section (101b) and the closed section (101c) are separated from each other by a radial recess (101e) which annularly surrounds the outer side of the housing cup (101), b. the free edge strip (106c or 109c) extending from the first end face (104a) is wider than the distance d between the middle section (101b) and the closed section (101c), so that the edge strip (106c or 109c) spans the distance d and is in direct contact with the contact element (112), c. The distance d is defined by the upper edge (101f) and the lower edge (101g) of the recess (101e) of the housing cup (101).

6. The energy storage battery cell according to claim 5, wherein the energy storage battery cell has at least one of the following additional features: a. the free edge strip extending from the first end face (104a) of the electrode-diaphragm assembly (104) is pressed inwardly toward the center of the housing cup (101) in the region of the recess (101e) of the housing cup (101), b. In the region of the recess (101e), an electrically insulating material (115) is arranged between the inner side of the housing cup (101) and the free edge strip extending from the first end face (104a) of the electrode-diaphragm complex (104), which electrically insulates the free edge strip from the potential of the housing cup (101).

7. The energy storage battery cell according to any one of the preceding claims, wherein the energy storage battery cell has at least one of the following additional features: a. the housing cup (101) has the same maximum outer diameter in the middle section (101b) and the closed section (101c), b. In the region of the depression ( 101 e ), the outer diameter of the housing cup ( 101 ) is reduced by 4 to 20 times the wall thickness of the housing cup ( 101 ) in this region.

8. The energy storage battery cell according to any one of the preceding claims, wherein the energy storage battery cell has at least one of the following additional features: a. the longitudinal edges (106a, 109a) along which the free edge strip extending from the first end face (104a) of the electrode-diaphragm assembly (104) extends form the surface on which the contact element (112) lies flat or into which the contact element (112) is pressed, b. the contact element (112) is dimensioned so as to cover at least 40%, preferably at least 60%, particularly preferably at least 80% of the first end face (104a), c. The contact element (112) is a disk or a polygonal plate, d. the contact element (112) has at least one through-hole, in particular at least one hole and / or at least one groove, e. the contact element (112) has a preferably uniform thickness in the range of 50 μm to 600 μm, preferably in the range of 150 μm to 350 μm, f. the contact element (112) has two mutually opposite planar sides and extends substantially in only one dimension, g. the contact element (112) has at least one bead, which is in the form of an elongated groove on one planar side of the contact element (112) and in the form of an elongated protrusion on the opposite planar side, wherein the contact element (112) is pressed into the surface formed by the longitudinal edges (106a, 109a) with the planar side with the elongated protrusion, h. In the region of the bead, the contact element (112) is welded to the longitudinal edge (106a, 109a) of the respective current collector, in particular via one or more weld seams arranged in the bead.

9. The energy storage battery cell according to any one of the preceding claims, wherein the energy storage battery cell has at least one of the following additional features: a. One or more openings (117a) are formed at the center and / or edge of the polar cap (117).

10. A method for producing an energy storage battery cell having the features of any one of claims 1 to 9, the method having the following features: a. providing a housing cup having a circular opening and an electrode-diaphragm complex having a first end surface and a second end surface as defined in claim 1, b. pushing the electrode-diaphragm complex into the housing cup through the circular opening of the housing cup with the second end facing forward, c. before or after step b., arranging a metal contact element on the first end surface and fixing it by welding, d. mounting the diaphragm and the pole cap on the contact element to form the cover assembly, e. Forming a weld between the diaphragm and the contact element.

Images