Energy storage cell having a cylindrical housing and method for production

Abstract

The invention proposes an energy storage cell (100; 300; 700) having a cylindrical housing which is closed in a liquid-tight fashion and has a first housing end side (140) and a second housing end side (150) and a housing lateral surface (200), as well as a method for producing the energy storage cell. The cylindrical energy storage cell (100; 300) comprises an electrode-separator assembly (104) which is arranged in the housing. The electrode-separator assembly (104) is in the form of a cylindrical winding which is formed from electrode strips (105, 108) and at least one strip-like separator (116, 117) and has a first and a second terminal winding end side (120, 130) and a winding lateral surface. Here, the electrode-separator assembly (104) is axially arranged in the housing such that the first winding end side (120) faces in the direction of the first housing end side (140) and the second winding end side (130) faces in the direction of the second housing end side (150). The energy storage cell is characterized in that the housing lateral surface (200) of the energy storage cell is formed from a spirally wound film or foil, preferably a spirally wound metal foil, and comprises at least two plies of the film or foil, preferably the metal foil.

Description

[0001] Energy storage cell with cylindrical housing and method for manufacturing

[0002] AREA OF APPLICATION

[0003] The present invention relates to a cylindrical energy storage cell with an electrode-separator assembly in the form of a coil and a method for its production.

[0004] STATE OF THE ART

[0005] Electrochemical energy storage elements are capable of converting stored chemical energy into electrical energy through a redox reaction. The simplest form of an electrochemical energy storage element is the electrochemical cell. It comprises a positive and a negative electrode, between which a separator is arranged. During a discharge, electrons are released at the negative electrode through an oxidation process. This results in an electron current that can be tapped by an external electrical consumer, for which the electrochemical cell serves as an energy supplier. At the same time, an ion current corresponding to the electrode reaction occurs within the cell. This ion current passes through the separator and is enabled by an ion-conducting electrolyte. The separator thus prevents direct contact between the electrodes.At the same time, it enables an electrical charge balance between the electrodes.

[0006] If the discharge is reversible, meaning it is possible to reverse the conversion of chemical energy into electrical energy during the discharge and recharge the cell, it is called a secondary cell. The commonly used designation for secondary cells is the anode for the negative electrode and the cathode for the positive electrode, which refers to the discharge function of the electrochemical cell.

[0007] Secondary lithium-ion cells are now used as energy storage cells for many applications because they can deliver high currents and are characterized by a comparatively high energy density. They are based on the use of lithium, which can migrate back and forth between the cell's electrodes in the form of ions. The negative and positive electrodes of a lithium-ion cell are typically formed by so-called composite electrodes, which include both electrochemically active and electrochemically inactive components.

[0008] In principle, any material capable of absorbing and releasing lithium ions can be considered as electrochemically active components (active materials) for secondary lithium-ion cells. Carbon-based particles, such as graphitic carbon, are used for the negative electrode. Lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium iron phosphate (LiFePO4), or derivatives thereof can be used as active materials for the positive electrode. The electrochemically active materials are usually contained in the electrodes in particle form.

[0009] As electrochemically inactive components, the composite electrodes generally comprise a flat and / or strip-shaped current collector, for example, a metallic foil, which serves as a carrier for the respective active material. The current collector for the negative electrode (anode current collector) can be made of copper or nickel, for example, and the current collector for the positive electrode (cathode current collector) can be made of aluminum, for example. Furthermore, the electrodes can comprise an electrode binder (e.g., polyvinylidene fluoride (PVDF) or another polymer, such as carboxymethyl cellulose), conductivity-enhancing additives, and other additives as electrochemically inactive components. The electrode binder ensures the mechanical stability of the electrodes and often also the adhesion of the active material to the current collectors.

[0010] Lithium-ion cells usually contain solutions of lithium salts such as lithium hexafluorophosphate (LiPF6) in organic solvents (e.g. ethers and esters of carbonic acid) as electrolytes.

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

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

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

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

[0015] WO 2017 / 215900 A1 describes cylindrical round cells in which the electrode-separator assembly and its electrodes are strip-shaped and in the form of a coil. The electrodes each have strip-shaped current collectors loaded or coated with electrode material. Oppositely polarized electrodes are arranged offset from one another within the electrode-separator assembly, so that the longitudinal edges of the current collectors of the positive electrodes emerge from the coil on one side and the longitudinal edges of the current collectors of the negative electrodes emerge from the coil on another side. To electrically contact the current collectors, the cells have sheet metal parts that sit flat on the end faces of the coil and are welded to the longitudinal edges of the current collectors. This makes it possible to electrically contact the current collectors and thus also the associated electrodes over their entire length.Cells with windings contacted in this way exhibit significantly reduced internal resistance. Consequently, high currents can be absorbed much more effectively, and heat can also be dissipated more effectively from the winding. Electrochemical energy storage cells typically have a metallic housing. The housing of cylindrical round cells often comprises a housing cup, which serves to accommodate the wound electrode-separator assembly, and a cover component that closes the opening of the housing cup. The housing cup can, for example, be a deep-drawn component, for example, made of aluminum, nickel-plated steel, or stainless steel, with a wall thickness in the range of 0.1 mm - 2 mm.

[0016] A seal is usually arranged between the cover component and the housing cup. This seal serves to seal the housing and also electrically insulate the cover component and the housing cup from each other. The seal is usually pulled over the edge of the cover component for assembly. To seal the cylindrical cells, for example, the opening edge of the housing cup can be bent radially inward over the edge of the cover component enclosed by the seal (flanging process), so that the cover component, including the seal, is positively secured in the opening of the housing cup.

[0017] To assemble the cells, the electrode-separator assembly must first be manufactured before the electrode-separator assembly is inserted into the cylindrical and metallic housing in a separate step, which is then sealed.

[0018] In the case of wound electrode-separator assemblies, the electrode coil itself is first produced on a winding machine, then transported to a separate assembly line and inserted into the cup.

[0019] A further disadvantage of this approach is that a certain amount of clearance, or play, is often required between the outer diameter of the coil and the inner diameter of the can to insert the coil into the can. This clearance remains unused in the assembled energy storage cell from an energy perspective. The relatively high weight of conventional housing cans is also detrimental to the cell's energy density. This can account for up to 15% of the total weight of a cell. Furthermore, conventional housing cans made of the aforementioned metals are comparatively expensive and, in the case of steel, often prone to rust, particularly around cut edges caused by manufacturing processes. Furthermore, the system technology for feeding and inserting the coil into the can is complex and cost-intensive. TASK AND SOLUTION

[0020] Against this background, the invention aims to provide an improved energy storage cell that allows optimal utilization of its volume. At the same time, the cell manufacturing process is to be simplified, thereby enabling cost savings in cell production.

[0021] This object is achieved by an energy storage cell having the features of claim 1. Furthermore, this object is achieved by a manufacturing method for such an energy storage cell according to the further independent claim 15. Advantageous embodiments of the energy storage cell are the subject of the dependent claims.

[0022] The energy storage cell according to the invention has a cylindrical, liquid-tight housing with a first housing end face and a second housing end face and a housing shell. The energy storage cell comprises the following features: a. The cylindrical energy storage cell comprises an electrode-separator assembly arranged in the housing; b. The electrode-separator assembly is in the form of a cylindrical coil formed from electrode strips and at least one strip-shaped separator, which has a first and a second terminal coil end face and a coil shell; c. The electrode-separator assembly is arranged axially in the housing such that the first coil end face points towards the first housing end face and the second coil end face points towards the second housing end face.

[0023] The core aspect of the invention is the following feature: d. The housing shell of the energy storage cell is formed from at least one spirally wound foil, preferably a spirally wound metal foil, and comprises at least two layers of the foil, preferably the metal foil.

[0024] The electrode strips preferably each comprise a strip-shaped current collector and a coating of an electrode material arranged thereon. The energy storage cell according to the invention can, in particular, be a cylindrical round cell. In other embodiments, it can also be a button cell, whereby a button cell differs from a cylindrical round cell in particular in that it is smaller, and in the case of a button cell, the height of the cell is smaller than its diameter.

[0025] According to the inventive concept, the energy storage cell according to the invention dispenses with a conventional metallic housing. Rather, the energy storage cell according to the invention is characterized in that the housing shell of the cell is formed from wound foil layers, in particular metal foil layers. The foil, in particular the metal foil, is present in at least two layers. In other words, the housing shell is formed from at least two turns of the foil, in particular the metal foil.

[0026] Housing shell

[0027] The housing shell preferably comprises 2 to 50 layers of film. 2 to 25 layers are particularly preferred, and 5 to 25 layers are most preferred.

[0028] The foil, in particular the wound metal foil, preferably has a thickness in the range of 4 to 300 μm, preferably 4 to 100 μm. A thickness of 4 to 50 μm is particularly preferred, and most preferably 4 to 25 μm.

[0029] The number of layers for the housing shell can be adjusted depending on the thickness of the foil used. The thinner the foil, the more layers may be required. The thickness of the foil used and the number of layers influence the strength and stability of the resulting housing shell. Furthermore, the size or form factor of the energy storage cell can also play a role in choosing the thickness of the foil and the number of layers. The smaller the energy storage cell, the less material can be sufficient to achieve the required stability of the housing shell.

[0030] Forming the foil as a metal foil can be preferable for many reasons. For example, a housing shell made of metal foil is usually sufficiently resistant to common liquid electrolytes, exhibits high mechanical strength, and can serve as a housing terminal. Furthermore, a housing shell made of metal foil has the particular advantage that the metallic material imparts particularly good heat-dissipating properties to the housing shell.

[0031] In some embodiments, however, the film used to form the housing shell can also be a plastic film. This is preferably free of pores that can be penetrated by an electrolyte and preferably has electrically insulating properties. Fiber-reinforced plastic films can be particularly preferred. A housing shell formed from such a film cannot serve as a housing pole. Corresponding pole feedthroughs through the housing can be provided for contacting the electrodes, or the housing end faces can, for example, be metallic and are in electrical contact with the electrodes. It is also possible to provide a pole feedthrough for contacting one of the electrodes and to make one of the housing end faces metallic for contacting the other electrode and to connect it electrically to the other electrode.

[0032] In other embodiments, it can be provided that the housing shell of the cell is formed from different foils, for example a multi-layer metal foil wound on the coil-shaped electrode-separator composite and a multi-layer plastic foil wound on the metallic foil layers, or vice versa.

[0033] Advantages of the invention

[0034] The inventive concept, with the formation of the housing shell from a wound foil, in particular a wound metal foil, offers several significant advantages. In particular, the energy storage cell according to the invention does not require a separate metallic housing cup to form the housing, into which the electrode-separator composite would have to be inserted in a separate work step and which would then have to be contacted, sealed, and closed accordingly. Rather, the inventive concept makes it possible to carry out the assembly of the energy storage cell largely on a winding machine on which the electrode-separator composite is already manufactured. With the inventive concept, a separate assembly line for inserting the electrode-separator composite and for assembling the housing can therefore be dispensed with.Another particular advantage of the inventive concept is that the interior of the energy storage cell can be optimally utilized. The previously mentioned clearance between the outer diameter of the winding and the inner diameter of the can is not required. The housing shell is wound directly onto the electrode-separator assembly, possibly separated from it only by a thin, electrically insulating layer. No clearance is provided between the winding and the housing shell to be formed. This allows the cell's interior volume to be optimally utilized for energy supply.

[0035] Avoiding a gap between the winding sleeve and the housing is also beneficial for optimal cell cooling. In conventional cells, this gap, usually filled with air, can form a thermal insulation layer that makes cell cooling difficult.

[0036] A further particular advantage of the inventive concept is that any inequalities in the winding diameter that may arise due to the coating process during the manufacture of the electrode strips can be optimally compensated. For example, if the coating with electrode material is already somewhat uneven, the diameter of the winding will be slightly larger or smaller for a given length of wound electrode strips. Even small fluctuations in diameter can lead to problems during assembly and difficulties when inserting the electrode-separator assembly into the housing cup. This problem is also completely avoided with the inventive concept.

[0037] Furthermore, the inventive concept also results in significant cost savings. Conventional deep-drawn housing cups are significantly more expensive than the foil, especially the metal foil, from which the housing shell is formed according to the invention.

[0038] Electrode-separator composite

[0039] The electrode-separator assembly is preferably first manufactured in a conventional manner. Preferably, the electrode strips, in particular an electrode strip for the anode and an electrode strip for the cathode, as well as the at least one strip-shaped separator, are first provided for this purpose. Within the electrode-separator assembly, the arrangement of these strips is, for example, as follows: first electrode strip (e.g., anode) - strip-shaped separator - second electrode strip (e.g., cathode) - strip-shaped separator. In the electrode-separator assembly, which is designed as a coil, the strip-shaped anode, the strip-shaped cathode, and the strip-shaped separator(s) are wound spirally.

[0040] To produce the electrode-separator assembly, the strip-shaped electrodes are preferably fed together with the at least one strip-shaped separator to a winding device and wound spirally therein, preferably around a winding axis, for example a winding mandrel.

[0041] In some embodiments, the electrodes and the at least one separator are wound onto a cylindrical or hollow-cylindrical winding core, which remains in the winding after winding. For this purpose, for example, a first strip-shaped separator can first be attached to the winding core, e.g., glued or welded. The electrode strips and another strip-shaped separator located between the electrode strips are inserted, and the winding process is started.

[0042] Alternatively, the roll can also be formed on a winding mandrel, which is pulled out of the roll again after the roll has been formed.

[0043] Within the electrode-separator assembly, the individual strips are not necessarily firmly connected to each other in the sense of being glued or laminated, but they are in contact with each other, preferably in a press contact.

[0044] It is also possible that a band-shaped electrode-separator composite is first formed from the band-shaped electrodes, with a band-shaped separator arranged between the electrodes, and that this electrode-separator composite is then processed into the coil.

[0045] The winding sleeve can be formed, for example, by a plastic film or an adhesive tape. It is also possible for the winding sleeve to be formed by one or more turns of the strip-shaped separator.

[0046] In particularly preferred embodiments, the electrode-separator assembly of the energy storage cell according to the invention is characterized by at least one of the following features a. to c.: a. One of the electrode strips of the electrode-separator assembly is an electrode strip with positive polarity, which comprises a strip-shaped cathode current collector having a first longitudinal edge and a second longitudinal edge parallel thereto and is coated on both sides with a positive electrode material; b. One of the electrode strips of the electrode-separator assembly is an electrode strip with negative polarity, which comprises a strip-shaped anode current collector having a first longitudinal edge and a second longitudinal edge parallel thereto and is coated on both sides with a negative electrode material; c. The at least one strip-shaped separator electrically insulates the oppositely polarized strip-shaped electrode strips from one another.

[0047] Preferably, the aforementioned features a. and b., and particularly preferably the aforementioned features a., b. and c. are implemented together.

[0048] Preferred electrochemical embodiment

[0049] In particularly preferred embodiments, the energy storage cell according to the invention can be a lithium-ion cell, wherein in principle all electrode materials known for lithium-ion cells, in particular for all secondary lithium-ion cells, can be used for the electrodes or the electrode strips of the energy storage cell.

[0050] In the negative electrodes, carbon-based particles, such as graphitic carbon or non-graphitic carbon materials capable of intercalating lithium, preferably also in particle form, can be used as active materials. Alternatively or additionally, lithium titanate (Li4Ti5O12 ) or a derivative thereof may be contained in the negative electrode, preferably also in particle form. Furthermore, the negative electrode may contain as active material at least one material from the group consisting of silicon, aluminum, tin, antimony, or a compound or alloy of these materials that can reversibly incorporate and de-incorporate lithium, for example silicon oxide (in particular SiO x with 0 < x < 2), optionally in combination with carbon-based active materials. Tin, aluminum, antimony, and silicon are capable of forming intermetallic phases with lithium. The lithium absorption capacity, particularly in the case of silicon, exceeds that of graphite or comparable materials by several times. Mixtures of silicon- and carbon-based storage materials are particularly suitable. Thin anodes made of metallic lithium are also suitable.

[0051] For the positive electrodes, suitable active materials include lithium metal oxide compounds and lithium metal phosphate compounds such as LiCoO2 and LiFePO4. Also particularly suitable is lithium nickel manganese cobalt oxide (NMC) with the molecular formula LiNi. x Mn y Co z O2 (where x + y + z is typically 1), lithium manganese spinel (LMO) with the molecular formula LiMn2O4, or lithium nickel cobalt aluminum oxide (NCA) with the molecular formula LiNi x Co y Al z O2 (where x + y + z is typically 1). Derivatives thereof, for example, lithium nickel manganese cobalt aluminum oxide (NMCA) with the molecular formula Li(NiO,4O,MnO,3O,AlO,O,5)O,8O,8O, or Li 1 +x M-0 compounds and / or mixtures of the above-mentioned materials can be used. The cathodic active materials are also preferably used in particulate form.

[0052] In addition, the electrodes of an energy storage cell according to the invention preferably contain an electrode binder and / or an additive to improve electrical conductivity. The active materials are preferably embedded in a matrix made of the electrode binder, with adjacent particles in the matrix preferably being in direct contact with one another. Conductive agents serve to increase the electrical conductivity of the electrodes. Suitable electrode binders are based, for example, on polyvinylidene fluoride (PVDF), lithium polyacrylate, styrene-butadiene rubber, or carboxymethyl cellulose, or mixtures of different binders. Suitable conductive agents include carbon black, fine graphite, carbon fibers, carbon nanotubes, and metal powder.

[0053] The energy storage cell according to the invention particularly preferably comprises an electrolyte, in the case of a lithium-ion cell, in particular an electrolyte based on at least one lithium salt, such as lithium hexafluorophosphate (LiPF6), dissolved in an organic solvent (e.g., in a mixture of organic carbonates or a cyclic ether such as THF or a nitrile). Other suitable lithium salts include, for example, lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(oxalato)borate (LiBOB).

[0054] Preferably, the layers of the positive and negative electrode material as well as the at least one band-shaped separator are impregnated with the electrolyte.

[0055] The at least one separator is preferably formed from an electrically insulating plastic film. It preferably has pores so that it can be penetrated by the liquid electrolyte. The plastic film can be made of a polyolefin or a polyether ketone, for example. Nonwovens and woven fabrics made of plastic materials or other electrically insulating sheet-like structures can also be used as separators. Separators with a thickness in the range of 5 μm to 50 μm are preferred.

[0056] However, it is also possible for the strip-shaped separator to be a separator made of a solid electrolyte, which has intrinsic ionic conductivity and does not require impregnation with a liquid electrolyte. The solid electrolyte can, for example, be a polymer solid electrolyte based on a polymer-conducting salt complex that exists as a single phase without any liquid component. A polymer solid electrolyte can have polyacrylic acid (PAA), polyethylene glycol (PEG), or polymethyl methacrylate (PMMA) as the polymer matrix. These can contain lithium conducting salts such as lithium bis(trifluoromethane)sulfonylimide (LiTFSI), lithium hexafluorophosphate (LiPF6), and lithium tetrafluoroborate (LiBF4).

[0057] Nominal capacity

[0058] The nominal capacity of a lithium-ion-based energy storage cell according to the invention, designed as a cylindrical round cell, is preferably up to 15,000 mAh. With a form factor of 21 x 70, the energy storage cell in one embodiment as a lithium-ion cell preferably has a nominal capacity in the range of 1,500 mAh to 7,000 mAh, particularly preferably in the range of 3,000 to 5,500 mAh. With a form factor of 18 x 65, the cell in one embodiment as a lithium-ion cell preferably has a nominal capacity in the range of 1,000 mAh to 5,000 mAh, particularly preferably in the range of 2,000 to 4,000 mAh.

[0059] In the European Union, manufacturer specifications regarding the nominal capacities of secondary energy storage cells are strictly regulated. For example, specifications regarding the nominal capacity of secondary nickel-cadmium cells must be based on measurements according to the standards IEC / EN 61951-1 and IEC / EN 60622; specifications regarding the nominal capacity of secondary nickel-metal hydride cells must be based on measurements according to the standard IEC / EN 61951-2; specifications regarding the nominal capacity of secondary lithium cells must be based on measurements according to the standard IEC / EN 61960; and specifications regarding the nominal capacity of secondary lead-acid cells must be based on measurements according to the standard IEC / EN 61056-1. Any specifications regarding nominal capacities in this application are preferably also based on these standards.

[0060] Preferred embodiments of current collectors / separators

[0061] The anode current collector band, the cathode current collector band and the at least one band-shaped separator of the cell according to the invention preferably have the following dimensions:

[0062] A length in the range of 0.5 m to 25 m;

[0063] A width in the range 40 mm to 145 mm.

[0064] The current collectors of the energy storage cell according to the invention serve to electrically contact electrochemically active components contained in the respective electrode material over as large an area as possible. In particular, the strip-shaped current collectors consist of a metal foil or are at least surface-metallized.

[0065] In the case of an energy storage cell according to the invention designed as a lithium-ion cell, suitable metals for the anode current collector include, for example, copper or nickel, or other electrically conductive materials, in particular copper and nickel alloys or nickel-coated metals. Materials of type EN CW-004A or EN CW-008A with a copper content of at least 99.9% can be used as copper alloys. Suitable nickel alloys include, in particular, alloys of the types NiFe, NiCu, CuNi, NiCr, and NiCrFe. Stainless steel is also generally suitable, for example, type 1.4303 or 1.4404 or type SUS304.

[0066] In the case of an energy storage cell according to the invention designed as a lithium-ion cell, aluminum or other electrically conductive materials, including aluminum alloys, are particularly suitable as the metal for the cathode current collector.

[0067] Suitable aluminum alloys for the cathode current collector include aluminum alloys of type 1235, 1050, 1060, 1070, 3003, 5052, Mg3, Mg212 (3000 series), and GM55. Also suitable are AlSi, AlCuTi, AlMgSi, AlSiMg, AlSiCu, AlCuTiMg, and AlMg. The aluminum content of these alloys is preferably above 99.5%.

[0068] Preferably, the anode current collector and / or the cathode current collector are each a strip-shaped metal foil with a thickness in the range of 4 pm to 30 pm.

[0069] With regard to the inventive design of the housing shell of the energy storage cell using a spirally wound foil, two variants are particularly preferred. In the first of these variants, the housing shell is formed by a terminal section of one of the current collectors, which is also included in the electrode-separator assembly. In the second variant, the housing shell is formed by a separate metal foil.

[0070] Formation of the housing shell from the terminal current collector section

[0071] According to the first variant, the energy storage cell according to the invention is characterized by at least one of the following additional features a. to c.: a. The spirally wound foil which forms the housing shell of the energy storage cell is a spirally wound terminal section of the strip-shaped cathode current collector which is not coated with the positive electrode material; b. The spirally wound foil which forms the housing shell of the energy storage cell is a spirally wound terminal section of the strip-shaped anode current collector which is not coated with the negative electrode material; c. The strip-shaped cathode current collector and the strip-shaped anode current collector have a substantially constant width over their entire length.

[0072] The aforementioned features a. and b. are to be considered as alternatives, so that in this variant the housing shell is formed either by the metal foil that also forms the cathode current collector of the electrode-separator assembly or by the metal foil that also forms the anode current collector of the electrode-separator assembly.

[0073] In a particularly preferred manner, the aforementioned features a. and c., or b. and c. are implemented in combination with one another.

[0074] In the case where the housing shell is formed from the uncoated cathode current collector strip, the structure of the electrode-separator assembly is preferably as follows: Viewed from the inside out, the negative electrode strip, including the anode current collector strip, ends first. The double-sided coating of the cathode current collector also ends in this area. However, the metal foil strip forming the cathode current collector continues. The strip-shaped separator(s) also continue, for example, for two or three more turns. Then the strip-shaped separator(s) also end, leaving only the uncoated cathode current collector strip. The cathode current collector strip is then wound in several turns to form the housing shell.

[0075] In the case where the housing shell is formed by the uncoated anode current collector strip, the structure of the electrode-separator assembly is preferably as follows: From the inside out, the positive electrode strip, including the cathode current collector strip, ends first. The coating of the anode current collector also ends in this area, but the anode current collector itself continues with the strip-shaped separator(s), for example, for two or three turns. Then the strip-shaped separators also end, leaving the uncoated anode current collector, which is wound in several turns to form the housing shell.

[0076] Formation of the housing shell from separate metal foil

[0077] In the second preferred variant of the energy storage cell according to the invention, the housing shell is formed by the separate metal foil (shell metal foil). The energy storage cell according to the invention is characterized by at least one of the following additional features a. to d.: a. The spirally wound foil that forms the housing shell of the energy storage cell is a spirally wound shell metal foil strip that is wound onto the wound shell of the electrode-separator composite; b. The wound shell of the electrode-separator composite is formed from an electrically insulating material; c. The shell metal foil strip has a substantially constant width over its entire length; d. The shell metal foil strip has a greater width than the strip-shaped cathode current collector and / or the strip-shaped anode current collector of the electrode-separator composite.

[0078] In particularly preferred embodiments, the aforementioned features a. and b., or a. to c., or a. to d. are implemented in combination with one another.

[0079] The electrically insulating material according to the aforementioned feature b. can, in particular, be windings of the at least one strip-shaped separator. Alternatively or additionally, a separate adhesive film or similar material can be applied to the electrode-separator assembly to form the winding jacket after the winding of the electrode-separator assembly or after the end of the electrode strips and, if applicable, the at least one strip-shaped separator.

[0080] It may be advantageous if the sheath metal foil strip for the housing sheath has a greater width than the strip-shaped current collectors of the electrode-separator assembly in order to simplify the subsequent connection between the housing sheath and the housing end faces, for example by welding.

[0081] However, it is also possible to use the same metal strip as the anode current collector or cathode current collector as the metal foil strip. Thus, after winding the electrode strips, it is possible to cut the electrode strips, form the winding sleeve by further winding at least one strip-shaped separator, then insert the same metal strip that is used as the anode current collector or cathode current collector in the anode or cathode between two turns of the separator, and then cut the separator, leaving only the metal strip to continue winding.

[0082] Choice of material for housing shell

[0083] In particularly preferred embodiments of the energy storage cell according to the invention, the energy storage cell is characterized by one of the following features a. to c. with regard to the material of the foil for the housing shell: a. The spirally wound metal foil that forms the housing shell of the energy storage cell is made of aluminum or an aluminum alloy; b. The spirally wound metal foil that forms the housing shell of the energy storage cell is made of copper or nickel or of a copper alloy or a nickel alloy. c. The spirally wound foil that forms the housing shell of the energy storage cell is made of plastic.

[0084] The aforementioned features a., b., and c. are generally to be understood as alternatives. However, it is also possible in principle for the housing shell to be formed from several metal foils made of different materials, or from a metal foil and a plastic foil.

[0085] The metal foil made of aluminum or an aluminum alloy according to the immediately above-mentioned feature a. can preferably be a terminal section of the cathode current collector (according to the above first preferred variant). The metal foil made of copper or nickel or of a copper alloy or a nickel alloy according to the above-mentioned feature b. can preferably be a terminal section of the anode current collector (according to the above first preferred variant). In other embodiments, these metal foils (according to the above second preferred variant) can be separate metal foils that are separate from the current collector strips and optionally have a different width.

[0086] The use of aluminum or an aluminum alloy as metal foil for the formation of the housing shell may be particularly preferred, since this is the more cost-effective material compared to copper or nickel.

[0087] However, the use of copper or nickel or a copper alloy or a nickel alloy for the metal foil that forms the housing shell can offer particular advantages, since these materials can generally be welded very well.

[0088] As stated above, in some embodiments, the at least one film may also be a plastic film. One possible starting material would be a polyether ketone.

[0089] In some particularly preferred embodiments, it is also possible to cover the spirally wound metal foil forming the housing shell with a plastic sleeve for mechanical stabilization and / or to seal the housing. This plastic sleeve can be formed, for example, from a single plastic molded part or two or more preformed plastic molded parts that are joined together by welding or gluing. Another possibility is to cover the shell and, if appropriate, at least parts of the housing end faces with a plastic sleeve using a liquid plastic or a liquid plastic precursor, for example by overmolding in a suitable injection mold.

[0090] Adhesive layer

[0091] In particularly preferred embodiments, the energy storage cell according to the invention is characterized by the following additional feature: a. The layers formed from the at least one foil, in particular the metal foil, which form the housing shell of the energy storage cell, are connected to one another by an adhesive layer arranged between the layers of the foil, in particular the metal foil.

[0092] Bonding the layers of the housing shell can be particularly advantageous, as it can improve the tightness of the housing. Conventional liquid or hot-melt adhesives or similar materials can be used for this purpose. For example, thermoplastics can be used, which are then thermally cured. Suitable plastics can also be sealed, for example, based on polyurethane or similar.

[0093] Adhesive tapes can also be used as the adhesive layer, with both sides capable of forming an adhesive bond to the layers of the film, especially the metal foil. Suitable for this purpose are, for example, adhesive tapes coated with an adhesive on both sides or tapes with intrinsic adhesive properties.

[0094] In preferred embodiments, such an adhesive layer can be sprayed or doctored onto the at least one film before winding. For example, the last few centimeters of a current collector, which is uncoated in this section and intended for forming the housing shell, can be pre-coated with a thermoplastic.

[0095] Formation of the housing front sides

[0096] In a particularly preferred embodiment of the energy storage cell according to the invention, the cell is characterized by at least one of the following additional features a. to d.: a. The first housing end face of the energy storage cell is formed by a round, in particular circular, metal disc or a metallic cap which comprises a round, in particular circular, base and a circumferential side wall; b. The metal disc or cap forming the first housing end face is connected to the housing shell by welding; c. The second housing end face of the energy storage cell is formed by a round, in particular circular, metal disc or a metallic cap which comprises a round, in particular circular, base and a circumferential side wall; d. The metal disc or cap forming the second housing end face is connected to the housing shell by welding.

[0097] In preferred embodiments, the aforementioned features a. and b., or the aforementioned features c. and d., are implemented in combination with one another. In principle, both housing end faces can also be formed by a round metal disc or a metallic cap, so that the aforementioned features a. and c., or, particularly preferably, the aforementioned features a. to d., are implemented in combination with one another.

[0098] The circumferential side wall of the cap is preferably an inwardly projecting collar or flange of the cap. The side wall is preferably at an angle of approximately 90° to the circular base. This circumferential side wall can facilitate the assembly and joining of the individual elements of the energy storage cell according to the invention and the connection of the housing shell to the housing end faces.

[0099] The round shape of the metal disc or the round shape of the cap base is characterized by its lack of corners, making it easy to integrate into the winding process. A circular shape is particularly preferred, as it is particularly well suited to a uniformly wound electrode-separator assembly with a circular base.

[0100] Pole feedthrough through the front of the housing

[0101] In a further preferred embodiment of the energy storage cell according to the invention, the cell is characterized by at least one of the following additional features a. and b.: a. An electrical contact pole is guided through the first and / or second housing end face, which electrically insulates from the respective housing end face and is electrically connected to one of the strip-shaped current collectors directly or via a metallic conductor; b. One of the strip-shaped current collectors is electrically connected directly or via a metallic conductor to the metal disc or cap forming the first housing end face or to the metal disc or cap forming the second housing end face.

[0102] In some preferred embodiments, the aforementioned features a. and b. are implemented in combination with one another, wherein one of the poles of the energy storage cell, for example the negative pole, is formed by a contact pole protruding from one housing end face, and the other pole of the energy storage cell, for example the positive pole, is formed by the opposite housing end face. The contact pole, which is guided through one of the end faces, can be, for example, a hollow bolt, through whose cavity a weld can be made so that the bolt can be fastened to an underlying component. The opening in the bolt can then be closed. The bolt itself is expediently electrically insulated from the rest of the housing end face, for example by a plastic, ceramic, or glass seal.For the assembly of the energy storage cell, it is particularly advantageous if a cap or disc forming the respective end face of the energy storage cell, together with the bolt insulated from it, forms a pre-assembled closure component that can be assembled as such.

[0103] Direct connection of a current collector to the front of the housing

[0104] In particularly preferred embodiments of the energy storage cell according to the invention, the cell is characterized by at least one of the following additional features a. to c.: a. The strip-shaped anode current collector comprises a main region which is loaded with a layer of the negative electrode material, and a free edge strip which extends along its first longitudinal edge and which is not loaded with the negative electrode material; b. The strip-shaped cathode current collector comprises a main region which is loaded with a layer of positive electrode material, and a free edge strip which extends along its first longitudinal edge and which is not loaded with the positive electrode material; c.The electrode strips are arranged within the electrode-separator assembly designed as a winding in such a way that the first longitudinal edge of the anode current collector or the first longitudinal edge of the cathode current collector emerges from one of the terminal winding end faces, or that the first longitudinal edge of the cathode current collector emerges from one terminal winding end face and the first longitudinal edge of the anode current collector emerges from the other terminal winding end face of the electrode-separator assembly.

[0105] Preferably, the aforementioned features a. and c., or b. and c., or, particularly preferably, a., b. and c. are implemented in combination with one another.

[0106] In the above-mentioned embodiment, in which the band-shaped current collectors are directly connected to the metal disc or cap forming the first housing end face or to the metal disc or cap forming the second housing end face, the first longitudinal edge of the anode current collector emerging from one of the terminal winding end faces or the first longitudinal edge of the cathode current collector is particularly preferably directly connected to the metal disc or cap, preferably by welding.

[0107] The edge strips of the current collectors, which protrude from the respective winding end faces and are free of electrode material, allow particularly advantageous contacting of the electrodes according to the following, particularly preferred feature: a. One of the band-shaped current collectors is directly connected to the metal disc or metallic cap forming the first housing end face or to the metal disc or metallic cap forming the second housing end face, wherein the first longitudinal edge or the free edge strip of the respective current collector sits directly on the metal disc or the base of the cap and is connected to it by welding, preferably over its entire length.

[0108] This form of direct contact between the current collectors via their longitudinal edges allows for contact between the electrodes along their entire length. Cells with this type of contact between the electrodes are characterized by significantly reduced internal resistance, allowing large currents to be absorbed much more effectively than with conventional electrode contact, and heat can also be dissipated more effectively from the winding.

[0109] In some preferred embodiments, this type of contact is provided either only for the anode or only for the cathode, preferably only for the cathode, wherein for the other electrode, in particular for the anode, contact can be provided, for example, via a contact strip or the like, as will be described below.

[0110] Electrical connection of a current collector via at least one contact lug

[0111] In further preferred embodiments of the energy storage cell according to the invention, at least one of the following additional features a. and b. is provided: a. At least one of the strip-shaped current collectors has at least one free section that is not coated with the electrode material and to which a metallic contact strip is welded; b. The metallic contact strip welded to the current collector emerges from one of the winding end faces.

[0112] Preferably, the aforementioned features a. and b. are implemented in combination with one another.

[0113] The metallic contact strip, also known as a conductor strip, allows for particularly easy contact between the electrodes. The metallic contact strip is preferably perpendicular to the winding or running direction of the electrode strip or the strip-shaped current collector.

[0114] Contacting one of the electrode strips via such a contact strip can be combined with other contacting options. In this case, one of the electrodes can be contacted via a contact strip, while the other electrode can be contacted in another way, for example, by directly connecting a longitudinal edge of one of the spirally wound electrode strips to a plate-shaped metal sheet on the end face.

[0115] The contact strips are preferably made of the same materials as the respective current collector. For example, a contact strip made of copper or a copper alloy is suitable for the anode, and a contact strip made of aluminum or an aluminum alloy is suitable for the cathode.

[0116] In a particularly preferred development of this aspect of the invention, the energy storage cell is characterized by the following additional feature a.: a. The metallic contact strip welded to the current collector is directly connected to the metal disc or cap forming the first housing end face or to the metal disc or cap forming the second housing end face, preferably by welding.

[0117] Preferably, only one of the current collectors is connected to the first or second housing end face via a metallic contact strip. The current collector of the oppositely polarized electrode is preferably contacted in a different way.

[0118] In the above-mentioned embodiment, in which the strip-shaped current collectors are connected via an electrical conductor to the metal disc or cap forming the first housing end face, or to the metal disc or cap forming the second housing end face, the electrical conductor is particularly preferably the contact strip. The contact strip can be welded directly to the metal disc or cap.

[0119] The winding end face, from which the contact strip or one of the longitudinal edges of the current collectors emerges, is formed by at least one longitudinal edge of the at least one band-shaped separator, which protrudes slightly beyond the coating of the electrode bands on the end face of the winding.

[0120] Targeted forming of the longitudinal edge of the current collectors

[0121] In particularly preferred embodiments, the energy storage cell according to the invention is characterized by at least one of the following additional features a. and b.: a. The first longitudinal edge of the anode current collector and / or the first longitudinal edge of the cathode current collector emerges from one of the terminal winding faces and has a spiral shape; b. At least the outer turn of the first longitudinal edge is bent in the direction of a central axis of the electrode-separator assembly or in the direction away from the central axis.

[0122] Preferably, the aforementioned features a. and b. are implemented in combination with one another.

[0123] Bending the first longitudinal edge of the current collectors projecting on one or both winding end faces is particularly advantageous in particular during assembly of the energy storage cell according to the invention, since in this way a front-side cap or a front-side disc can be attached particularly well and efficiently to the respective winding end face.

[0124] Metallic contact element

[0125] In particularly preferred embodiments of the energy storage cell according to the invention, the cell is characterized by at least one of the following additional features a. to e.: a. The energy storage cell comprises at least one metallic contact element, optionally including a separate electrical conductor fixed to the contact element, which is connected to the first longitudinal edge of the cathode current collector or the anode current collector by welding, in some preferred embodiments over its entire length, and via which this current collector is electrically connected to the metal disc or cap forming the first housing end face or to the metal disc or cap forming the second housing end face; b. The contact element sits flat on the first longitudinal edge of the cathode current collector or the anode current collector; c.The contact element comprises a first element which sits flat on the first longitudinal edge of the current collector emerging from the first or second terminal end face and extends parallel to the respective winding end face, and comprises a second element which adjoins the first element at an angle and via which the first element is electrically connected to the metal disc or cap forming the first housing end face or to the metal disc or cap forming the second housing end face; d. The contact element is directly connected, in particular by welding, to the metal disc or cap forming the first housing end face or to the metal disc or cap forming the second housing end face; e. The contact element is in contact, directly or via an electrical conductor, with an electrical contact pole guided through the first and / or second housing end face.

[0126] In particularly preferred embodiments, the aforementioned features a. and b., or a. and b. and c., or a. and b. and c. and d., or the features a. to e. are implemented in combination with one another.

[0127] In particular, it is preferred if such a contact element sits on the first longitudinal edge of the anode current collector.

[0128] The contact element is preferably a sheet metal component, for example in the form of a cap or disc, or in the form of a strip. The sheet metal component preferably has a thickness in the range of 0.05 to 1.0 mm.

[0129] The contact element can also be a star-shaped sheet metal component.

[0130] The energy storage cell preferably comprises an insulating element that electrically insulates the contact element from a metal disc or cap forming the housing end face by preventing direct contact between the contact element and the metal disc or cap. In this embodiment, a contact pole according to the aforementioned feature e. is particularly preferably provided, whereby the electrical contact is directed to the outside. The contact pole, for example, a conventional contact pin, contacts the contact element, which in turn is in electrical contact with the respective electrode.

[0131] This implementation of the electrical contact with a contact pole can be provided in particular for the anodic side, whereas the aforementioned feature d. can be provided, for example, on the cathodic side of the energy storage cell.

[0132] Alternatively, in a preferred embodiment, a contact element can be omitted, for example on the cathodic side, so that the housing end face on the cathodic side is formed, for example, by a metal disc or a metallic cap that is directly in contact with the free edge strip of the cathode current collector protruding from this side of the winding. Alternatively, an electrical connection can also be established via a metallic contact strip as described above.

[0133] There are two preferred variants (variant A and variant B) for electrically connecting the contact element, which is preferably connected by welding to the first longitudinal edge or the free edge strip of the current collector emerging from the first terminal winding end face, to the metal disc or metallic cap forming the housing end face, which can each also be referred to as a cover component.

[0134] According to variant A, the cell according to the invention is characterized by at least one of the immediately following features a. to c.: a. The contact element is directly connected to the cover component. b. The contact element comprises a first element or a first section that sits flat on the first longitudinal edge of the current collector emerging from the terminal winding end face and extends parallel to the winding end face. c. The contact element comprises a second element or a second section that adjoins the first section at an angle and via which the first section is electrically connected to the cover component.

[0135] It is preferred that the immediately above features a. and b. are implemented in combination. Particularly preferred are the immediately above features a. to c. in combination.

[0136] According to variant B, the cell according to the invention is characterized by at least one of the immediately following features a. and b.: a. The contact element is connected to the cover component via the separate electrical conductor. b. The contact element sits flat on the first longitudinal edge of the current collector emerging from the terminal winding end face. It is preferred that the immediately above features a. and b. are implemented in combination.

[0137] If the separate electrical conductor is used, it is preferably made of the same material as the contact element itself.

[0138] Of course, not only the first longitudinal edge of the current collector emerging from one terminal winding end face must be electrically contacted. Rather, the first longitudinal edge of the current collector emerging from the other terminal winding end face must also be electrically contacted. According to the invention, the following two variants C and D are preferred:

[0139] According to variant C, the cell according to the invention is characterized by the immediately following feature a.: a. The first longitudinal edge of the current collector emerging from the other terminal winding face rests directly on a metal disc or cap forming this housing face and is connected to it by welding.

[0140] According to variant D, the cell according to the invention is characterized by the immediately following feature b.: b. The energy storage cell comprises a contact element which is welded to the first longitudinal edge of the current collector emerging from the other terminal winding end face and via which this current collector is electrically connected to a metal disc or metallic cap forming this housing end face.

[0141] In both cases, the longitudinal edge of the current collector emerging from the other terminal winding end face can be electrically and / or thermally connected over its entire length, as in the case of the current collector emerging from the opposite terminal winding end face.

[0142] The energy storage cell according to the invention is particularly preferably characterized by the following feature a.: a. The current collector emerging from the first terminal winding end face is the anode current collector and the current collector emerging from the second winding end face is the cathode current collector.

[0143] This configuration is particularly advantageous when the foil forming the housing shell is made of aluminum or an aluminum-containing alloy, since the cathode current collector is also preferably made of aluminum.

[0144] In a particularly preferred embodiment of the invention, the contact element electrically connected to the anode current collector is characterized by at least one of the following features a. and b.: a. The contact element is made of nickel or copper or titanium or a nickel or copper or titanium alloy or stainless steel, for example, type 1.4303 or 1.4404 or type SUS304, or nickel-plated copper. b. The contact element is made of the same material as the anode current collector.

[0145] It is preferred that the immediately above features a. and b. are implemented in combination.

[0146] Copper is particularly preferred as the material for the contact element connected to the anode current collector.

[0147] In embodiments in which the cathode current collector is also electrically connected via a contact element, this contact element is characterized by at least one of the following features a. and b.: a. The contact element is made of aluminum or an aluminum alloy. b. The contact element is made of the same material as the cathode current collector.

[0148] It is preferred that the immediately above features a. and b. are implemented in combination.

[0149] Aluminum is particularly preferred as the material for the contact element that is connected to the cathode current collector. Contact elements that can be used according to the invention for contacting the longitudinal edges of the current collectors are particularly preferably characterized by at least one of the immediately following features a. to g.: a. They have a preferably uniform thickness in the range from 50 pm to 600 pm, preferably in the range from 150 pm to 350 pm. b. They have two opposite flat sides and extend essentially in only one dimension. c. They are designed as a disk or as a polygonal plate or in a star shape or comprise such a disk or plate. d. They are dimensioned such that they cover at least 40%, preferably at least 60%, particularly preferably at least 70% of the first terminal and / or the second terminal winding end face. e.They have at least one opening, in particular at least one hole and / or at least one slot. f. They have at least one bead, which is formed as an elongated depression on one flat side of the contact element and as an elongated elevation on the opposite flat side, wherein they rest on the first longitudinal edge of the respective current collector with the flat side bearing the elongated elevation. g. They are welded to the first longitudinal edge of the respective current collector in the region of the bead, in particular via one or more weld seams arranged in the bead.

[0150] It is particularly preferred that the immediately above features a., b., and d. are implemented in combination with one another. In a preferred embodiment, features a., b., and d. are implemented in combination with one of features c. or e., or features f. and g. Particularly preferably, all features a. to g. are implemented in combination with one another.

[0151] Covering the winding end face as extensively as possible is important for the thermal management of the energy storage cell according to the invention. The larger the cover, the easier it is to contact the first longitudinal edge of the respective current collector over its entire length. The heat generated in the electrode-separator assembly can thus be effectively dissipated via the contact element(s).

[0152] Current collector pretreatment

[0153] In some embodiments, it has proven advantageous to pretreat the longitudinal edge of a current collector before a contact element is attached. In particular, at least one recess can be crimped into the longitudinal edge, corresponding to the at least one bead or elongated elevation provided on the corresponding flat side of the contact element. This also applies to the attachment of a metal disc or cap that forms a housing end face and that may be directly contacted with the respective winding end face. This metal disc or cap can also be provided with one or more beads, which can facilitate contact with the current collector edges.

[0154] The longitudinal edges of the current collectors can also be subjected to directional deformation through pretreatment. For example, they can be bent in a defined direction, particularly toward a central axis of the electrode-separator assembly, as already described above in connection with the contacting of the metal disc or cap.

[0155] The at least one opening in the contact elements can be used to particular advantage to impregnate the electrode-separator assembly with an electrolyte during assembly of the energy storage cell. This opening can then be closed, for example, with a blind rivet.

[0156] Preferred feature combinations

[0157] In a particularly preferred embodiment of the energy storage cell according to the invention, the cell is characterized by at least one of the following features a. to f., preferably by a combination of the following features a. to f.: a. The spirally wound foil which forms the housing shell of the energy storage cell is a spirally wound terminal section of the strip-shaped cathode current collector which is not coated with the positive electrode material, or a spirally wound terminal section of the strip-shaped cathode current collector which is not coated with the positive electrode material; b. The first housing end face of the energy storage cell is formed by a metallic cap which comprises a round, in particular circular, base and a circumferential side wall, the cap having an opening edge which delimits the circumferential side wall; c.The opening edge of the cap forming the first housing end face is connected to the housing shell by welding; d. The second housing end face of the energy storage cell is formed by a metallic cap comprising a round, in particular circular, base and a circumferential side wall; e. The spirally wound foil rests from the outside against the side wall of the cap forming the second housing end face; f. The spirally wound foil is connected to the side wall of the cap forming the second housing end face by a circumferential weld seam.

[0158] This embodiment of the energy storage cell according to the invention according to the aforementioned features a. to f. is characterized in particular by the fact that the housing shell is formed by a terminal section of one of the current collectors, which is wound around the electrode-separator assembly. This is preferably the cathode current collector, which is made of aluminum or an aluminum alloy.

[0159] In this case, it can preferably be provided that the first housing end face forms the negative pole of the cell, i.e. the anodic side, and the second housing end face forms the positive pole, i.e. the cathodic side of the cell.

[0160] Particularly advantageously, in addition to the aforementioned features a. to f., the first housing end face additionally comprises a contact element. This contact element is preferably directly electrically contacted with the free edge regions of the anode current collector projecting on this side of the winding. Furthermore, the contact element is preferably electrically insulated from the cap forming this first housing end face. In addition, a terminal feedthrough is preferably provided on this housing end face, which leads the electrical contact, i.e., the negative terminal, to the outside on this end face of the cell.

[0161] In another preferred embodiment of the energy storage cell according to the invention, the cell is distinguished by at least one of the following features a. to f., wherein preferably a combination of these following features a. to f. is provided: a. The spirally wound foil which forms the housing shell of the energy storage cell is a spirally wound shell foil strip, in particular a shell metal foil strip, which is wound onto the winding shell of the electrode-separator composite; b. The first housing end face of the energy storage cell is formed by a metallic disk, wherein the disk has a boundary edge; c. The boundary edge of the disk forming the first housing end face is connected to the housing shell by welding; d.The second housing end face of the energy storage cell is formed by a metallic cap comprising a round, in particular circular, base and a circumferential side wall; e. The spirally wound foil rests from the outside against the side wall of the cap forming the second housing end face; f. The spirally wound foil is connected to the side wall of the cap forming the second housing end face by a circumferential weld seam.

[0162] In contrast to the previous embodiment, an energy storage cell according to this preferred embodiment is characterized in that not one of the current collectors forms the housing shell, but rather that a separate shell foil strip, in particular a shell metal foil strip, is provided for this purpose, which is wound onto the winding shell of the electrode-separator assembly. This shell foil strip can have a somewhat greater width than the electrode strips and the strip-shaped separators of the electrode-separator assembly, so that the wound housing shell has a greater height than the winding. The housing end faces can be designed accordingly, in that, in particular in the region of the first housing end face, a metallic disk is provided instead of a metallic cap. This allows a flush closure of the first housing end face to be realized in a particularly advantageous manner.Furthermore, this embodiment of the energy storage cell can be designed in a manner comparable to the previously described embodiment of the energy storage cell.

[0163] It may also be preferred that the foil strip, in particular the metal foil strip, be thicker than the current collectors of the electrode strips. Fewer windings are then required to form the housing shell.

[0164] In preferred embodiments of the energy storage cell according to the invention, an insulating element is expediently provided at least in the region of one of the end faces of the cell. The insulating element can, in particular, electrically insulate the metal disc or the cap forming the first housing end face from a contact element provided in this region and from the upper region of the winding in this region of the cell.

[0165] Insulating element

[0166] The insulating element can be implemented as follows, wherein in a first embodiment the energy storage cell according to the invention is distinguished by at least one of the following features a. to c.: a. The at least one insulating element is or comprises an insulating tape which is applied to the edge which delimits the winding end face and protects this from direct contact with the inside of the housing end face and / or the housing shell. b. The at least one insulating element is or comprises an annular molded part made of plastic with a preferably L-shaped cross section, which is applied to the edge which delimits the winding end face and protects this from direct contact with the inside of the housing end face and / or the housing shell. c. The insulating tape or the annular molded part made of plastic has a thickness in the range from 10 μm to 200 μm.

[0167] It is preferred that the immediately above features a. and c., or b. and c., are implemented in combination with one another.

[0168] The insulating tape can, for example, be a Kapton / polyimide adhesive tape.

[0169] The ring-shaped plastic part, preferably with an L-shaped cross-section, can be manufactured by injection molding, for example, and slid onto the edge to be protected. It can be made of Teflon or polyamide, for example.

[0170] In a further preferred embodiment of this aspect of the invention, the energy storage cell according to the invention is characterized by at least one of the immediately following features a. and b.: a. The at least one insulating element is or comprises an electrically insulating plastic coating that surrounds an edge of the contact element. b. The electrically insulating coating is formed by overmolding the edge of the contact element.

[0171] It is preferred that the immediately above features a. and b. are implemented in combination.

[0172] Basically, any thermoplastic material with electrically insulating properties is suitable for overmolding the edge of the contact element. Polyamide, for example, is suitable.

[0173] If necessary, a combination of these designs of the insulating element can also be provided, wherein an insulating strip or annular molded part made of plastic is realized in addition to a plastic coating of the edge of the contact element.

[0174] In particularly preferred embodiments, the energy storage cell according to the invention is characterized by at least one of the following additional features: a. The metallic cap, which forms at least one of the housing end faces, has a circumferential recess, in particular an annular recess, in its edge region, which is delimited outwardly by the circumferential side wall of the metallic cap; b. The circumferential side wall of the metallic cap lies flat against the foil that forms the housing shell.

[0175] Preferably, the aforementioned features a. and b. are implemented in combination with one another.

[0176] The particular advantage of this design lies primarily in the fact that the circumferential recess in the metallic cap offers a particularly good engagement option for welding the film that forms the housing shell to the housing front, i.e. to the metallic cap. This recess makes it particularly suitable, for example, to apply a laser beam in such a way that, in order to weld the housing shell to the cap, it first penetrates the (usually thicker) side wall of the metallic cap before it hits the film layers of the housing shell. It has been found that this produces a particularly stable connection between the housing shell and the housing front. In particular, the laser beam can be applied in such a way that it penetrates all film layers of the housing shell from the inside out.

[0177] The recess itself can be designed, in particular, as an annular gap or groove and can be produced, for example, during a deep-drawing process. It preferably has a triangular cross-section.

[0178] Inventive method

[0179] The invention further comprises a method for producing an energy storage cell with a cylindrical, liquid-tight housing with a first housing end face and a second housing end face and a housing shell according to the above description. This method comprises the following steps: a. An electrode-separator assembly in the form of a coil with two terminal coil end faces and a coil shell is produced on a winding machine, wherein the electrode-separator assembly is formed, in particular wound, from electrode strips, between which at least one strip-shaped separator is arranged, wherein the electrode strips preferably each comprise a strip-shaped current collector coated with electrode material; b. The housing shell is formed by winding a foil, in particular a metal foil.

[0180] The housing shell of the energy storage cell is particularly preferably formed by winding the foil, in particular the metal foil, spirally around the electrode-separator composite, in particular such that it comprises at least two layers of the foil, in particular the metal foil.

[0181] The current collectors are preferably coated on both sides with electrode material.

[0182] The electrode-separator assembly is preferably manufactured in a conventional manner on a winding machine. The key difference from conventional manufacturing processes for energy storage cells with a wound electrode-separator assembly lies in the formation of the housing shell. According to the invention, the housing shell is formed by winding at least two layers of foil, in particular metal foil, onto the wound shell of the electrode-separator assembly. The associated advantages, firstly with regard to the optimal utilization of the internal volume of the energy storage cell and, secondly, above all, the significantly simplified manufacturing process, have already been explained in connection with the energy storage cell itself.In particular, this process allows for a significant simplification of the system technology and associated cost savings, as the housing shell can be produced on the winding machine by continuing the winding process. A separate assembly line for inserting the coil into a housing and assembling the housing is no longer necessary.

[0183] Two variants of the method according to the invention are particularly preferred. In the first variant, the method is characterized by the immediately following additional feature a.: a. To form the housing shell of the energy storage cell, the housing shell is formed from a terminal section of one of the current collectors after the electrode-separator assembly has been manufactured.

[0184] This terminal section of the ribbon-shaped current collector is not coated with electrode material.

[0185] In the second variant, the method is characterized by the immediately following additional feature b.: b. To form the housing shell of the energy storage cell, after the electrode-separator composite has been manufactured, a separate shell foil, in particular a separate shell metal foil, is wound onto the winding shell of the electrode-separator composite.

[0186] For further details of the method and the energy storage cell that can be produced thereby, reference is made to the above description of preferred embodiments of the energy storage cell according to the invention.

[0187] In preferred embodiments, the method according to the invention comprises the following additional feature: a. After winding at least two layers of the foil, in particular the metal foil, to form the housing shell on the winding shell of the electrode-separator composite, the formed housing shell is welded to the edge regions of the housing end faces, in particular by laser welding.

[0188] By welding the housing shell formed by the metal foil layers to the edge areas of the housing end faces, a liquid-tight housing can be created in a particularly advantageous manner. Such welding is widely used in the assembly of energy storage cells and can be carried out very accurately and precisely, even in an automated manner.

[0189] Depending on the specific design of the housing end faces, which, as described above, can be realized as a metallic disc or cap, or in the form of a combination of a cap with a contact element or a disc with a contact element, the welding can take place in different areas. For example, it is possible for the metal foil layers forming the housing shell to be wrapped from the outside over a circumferential side wall of a metallic cap forming the housing end face. In this case, the housing shell can be attached and sealed to the cap using laser welding across the entire material thickness.

[0190] In other embodiments, it is possible for the foil layers forming the housing shell, in particular the metal foil layers, to be wound in such a way that a flush finish is created at the edge region of the spirally wound foil strip. In the area of ​​this flush finish, welding to a metal disc or metal cap on the front side of the housing can be performed, for example, by laser welding at the seam.

[0191] With regard to the welding of the foil-wound housing shell to the housing end faces, the method according to the invention is particularly preferably characterized by at least one of the following additional features: a. The welding is carried out by laser welding; b. The welding is carried out in such a way that a laser beam first penetrates the side wall of the metallic cap before it strikes the foil layers of the housing shell; c. At least one of the housing end faces is formed by a metallic cap with a circumferential recess according to the above description, the recess being delimited on the outside by the side wall of the cap.

[0192] Preferably, the aforementioned features a. and b., and particularly preferably the aforementioned features a. to c., are implemented in combination with one another.

[0193] The circumferential recess of the metallic cap according to the aforementioned feature c. has an outer first recess side (the inner side of the side wall of the cap) and an inner second recess side, which delimit the circumferential recess on both sides.

[0194] The circumferential recess in the metallic cap provides a very advantageous way of applying a welding beam, especially a laser beam, in such a way that the welding beam penetrates the side wall of the front cap and welds the foil layers forming the housing shell to the circumferential side wall of the cap. Such a weld, which starts at the rigid metallic material of the front element and welds the foil layers starting from the rigid metallic material, has proven particularly advantageous.

[0195] In preferred embodiments of the method according to the invention, at least one of the following additional features a. and b. is provided: a. The first and / or the second housing end face of the energy storage cell are formed by a round metal disc or a metallic cap comprising a round base and a circumferential side wall, wherein after the winding of the electrode-separator assembly, the first and / or the second winding end face are welded to the round metal disc or the metallic cap before the housing shell of the energy storage cell is formed; b.To form the first and / or the second housing end face of the energy storage cell, at least one contact element, optionally including a separate electrical conductor fixed to the contact element, is welded to the first and / or the second winding end face before the housing shell of the energy storage cell is formed, wherein preferably the contact element is electrically insulated from the metal disc or cap forming the first housing end face or from the metal disc or cap forming the second housing end face.

[0196] Preferably, the aforementioned features a. and b. are implemented in combination with one another, whereby on one side of the energy storage cell, one winding end face is preferably directly contacted with the metal disc or cap forming the housing end face. On the other side, in addition to the metal disc or cap forming the housing end face, a contact element is provided, to which the corresponding winding end face is connected.

[0197] To simplify the contacting of the winding end faces with the metal disc or the metallic cap or the contact element, the following additional feature is provided in preferred embodiments: a. Before welding the winding end faces of the electrode-separator assembly to the round, in particular circular, metal disc and / or to the metallic cap and / or to the contact element, the edge region of the current collector which may emerge on the respective side of the electrode-separator assembly at the winding end face and which is free of electrode material is bent in the direction of a central axis of the electrode-separator assembly.

[0198] As already explained above in connection with the energy storage cell according to the invention, it can be provided that the metallic disc or metallic cap forming a housing end face, or optionally the contact element, have an opening or recess. This opening or recess can be used during assembly of the energy storage cell according to the invention to introduce an electrolyte fluid into the interior of the energy storage cell in order to impregnate the electrode-separator assembly with it. The opening or recess can then be closed, for example, using a blind rivet.

[0199] Furthermore, within the scope of the method according to the invention for producing the energy storage cell, at least one insulating means is advantageously used to prevent a short circuit between the cell's electrodes. This insulating means is preferably placed between a contact element and the metallic disc or cap forming the respective housing end face of the cell.

[0200] For further details regarding this insulating material, please refer to the above description. In particular, the insulating material can be applied after the winding end faces have been connected to the metallic discs or caps forming the housing end faces, or, if necessary, to a contact element. Only then is the winding of the foil layers to form the housing shell carried out. For example, a ring-shaped insulating material or an insulating tape is suitable for this purpose, which is applied to the edge of the winding that lies in the area of ​​the housing end face to be insulated.

[0201] In a particularly preferred embodiment of the method according to the invention, the foil layers, in particular the metal foil layers, which form the housing shell, are glued together during the method. For this purpose, the metal foil strip or a corresponding section of the metal foil strip intended for forming the housing shell can be provided in advance with an adhesive layer, which is sprayed on or doctored on, for example. This can be a liquid adhesive, a hot melt adhesive, or a thermoplastic adhesive. When using a thermoplastic adhesive, the housing shell can be sealed, in particular subsequently, by curing the adhesive. With regard to this adhesive, reference is also made to the above explanations in connection with the energy storage cell according to the invention.

[0202] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments in conjunction with the drawings. The individual features can be implemented individually or in combination with one another.

[0203] BRIEF DESCRIPTION OF THE DRAWINGS

[0204] In the drawings shows:

[0205] Figure 1 Longitudinal section through an energy storage cell according to the invention;

[0206] Figure 2 Longitudinal section through a further embodiment of an inventive

[0207] energy storage cell;

[0208] Figure 3 Schematic representation of the components of an electrode-separator assembly;

[0209] Figure 4 Schematic representation as a plan view of an electrode-separator assembly with inventive design of the housing shell of the energy storage cell;

[0210] Fig. 5 Schematic longitudinal sectional views (A - C) of further embodiments of an energy storage cell according to the invention; and Fig. 6 Schematic longitudinal section through a further embodiment of an energy storage cell according to the invention.

[0211] DESCRIPTION OF PREFERRED EMBODIMENTS

[0212] Fig. 1 shows a preferred embodiment of an energy storage cell 100 according to the invention. Located at the center of the cell is an electrode-separator assembly 104, formed from a winding of electrode strips 105, 108 and strip-shaped separators. For the sake of clarity, the strip-shaped separators are not shown here.

[0213] The electrode-separator assembly 104 in the form of a coil is arranged axially within the energy storage cell 100. The electrode-separator assembly 104 comprises a first coil end face 120 and a second coil end face 130. The first coil end face 120 is located in the region of the first housing end face 140. The second coil end face 130 is located in the region of the second housing end face 150. For example, the negative pole of the cell is located in the region of the first housing end face 140, and the positive pole of the cell is located in the region of the second housing end face 150.

[0214] The electrode-separator assembly 104 is designed such that the electrode strips 105, 108 each have a longitudinal edge that is not coated with electrode material. These free longitudinal edges of the electrode strips 105, 108 protrude from the electrode-separator assembly 104 at the opposite winding end faces 120, 130. In the exemplary embodiment illustrated here, the uncoated edge of the anode current collector of the negative electrode 105 protrudes from the first winding end face 120. The uncoated edge of the cathode current collector of the positive electrode 108 protrudes from the second winding end face 130. The electrical contact between the electrodes is established via these edge regions of the current collectors. For this purpose, a metallic cap 160, which is equipped with a circumferential side wall 161, is provided on the second winding end face 130.The metallic cap 160 is equipped with several beads 162, which facilitate electrical contact with the cathode current collector through welding. The metallic cap 160 also forms the second housing end face 150.

[0215] In the area of ​​the first winding end face 120, a metallic contact element 170 is arranged, which is designed in the form of a metallic disk with a plurality of beads 171. Here, too, electrical contact is made with the edge region of the anode current collector free of electrode material via a weld. The first housing end face 140 is formed on this side by a metallic cap 180 with a circumferential side wall 181. In the center of the metallic cap 180 is a terminal feedthrough 190, through which a terminal bolt 191 is guided. The terminal bolt 191 is electrically insulated from the metallic cap 180 by an insulating means 192, for example, an insulating ring. The terminal bolt 191 is in electrical contact with the contact element 170, so that the anodic potential is conducted to the outside via the terminal bolt 191.

[0216] An insulating means 193, for example a circumferential insulating ring or a circumferential insulating tape, is placed between the contact element 170 and the upper edge of the electrode-separator assembly on this side of the cell on the one hand and the metallic cap 180 on the other hand.

[0217] According to the invention, the housing shell 200 of the energy storage cell 100 in this embodiment is formed by a multilayer metal foil wound onto the electrode-separator composite 104. In this exemplary embodiment, the metal foil forming the housing shell 200 is a continuous winding of the metal foil strip that forms the cathode current collector of the positive electrode 108 and is not coated with electrode material.

[0218] To produce the housing shell 200, the electrode-separator assembly 104 is first wound on a winding machine in a conventional manner. A strip-shaped separator is provided between each electrode strip. Viewed from the inside outward, one electrode strip runs out first, followed simultaneously or slightly later by the coating of the other electrode strip, with the strip-shaped separators and the current collector of the other electrode strip continuing. After, for example, two further turns, the strip-shaped separators also end, thus completing the winding of the electrode-separator assembly. The current collector of the other electrode strip, however, still remains.

[0219] The winding end contact is now made on both sides of the electrode-separator assembly using a metallic cap, a metallic disk, or a contact element. For this purpose, the remaining current collector strip is expediently cut slightly, for example, to facilitate the placement of the metallic cap 160. To increase the accuracy of fit when placing the cap 160 and the contact element 170, the free edge areas of the spirally wound current collectors, which protrude from the electrode-separator assembly at both winding end faces, can be bent toward the center of the winding. After welding the cap 160 and the contact element 170, the winding of the remaining current collector strip is continued so that these metal foil layers form the housing shell 200.

[0220] In the embodiment illustrated in Fig. 1, the winding of the cathode current collector strip or the metal foil forming the housing shell 200 is carried out such that the metal foil rests on the outer side of the circumferential side wall 161 of the metal cap 160 in the region of the second housing end face 150. In the region of the first housing end face 140, the edge of the metal foil forming the housing shell 200 is flush such that the metal cap 180, with its circumferential side wall 181, can sit on this flush edge of the metal foil forming the housing shell 200. In the region of the second housing end face 150, the metal foil layers forming the housing shell 200 are attached and sealed by laser welding across the entire material thickness. In the area of ​​the first housing end face 140, laser welding is performed at the seam between the flush edge of the housing shell 200 and the opening edge of the side wall 181 of the cap 180.The arrows in Fig. 1 indicate the welding starting points.

[0221] In preferred embodiments of the energy storage cell 100, the metallic cap 160 on the second end face 150 can be formed from aluminum or an aluminum alloy. The cathode current collector is also preferably formed from aluminum or an aluminum alloy. The contact element 170 on the first end face 140 is preferably formed from copper or a copper alloy. The anode current collector is also preferably formed from copper or a copper alloy.

[0222] Fig. 2 shows a further embodiment of an energy storage cell 300 according to the invention, which is largely comparable to the embodiment of the energy storage cell 100 from Fig. 1. The corresponding elements are therefore provided with the same reference numerals, and in this context, reference is made to the description of Fig. 1. In contrast to the embodiment from Fig. 1, the housing shell 200 in the energy storage cell 300 is not formed by a continuous current collector strip, but by a separate shell metal foil wound onto the electrode-separator composite 104.

[0223] In the embodiment illustrated in Fig. 2, the sheath metal foil forming the housing shell 200 has a slightly greater width than the electrode strips and strip-shaped separators forming the electrode-separator composite 104. Therefore, the wound housing shell 200 protrudes somewhat further beyond the first winding end face 120 with the contact element 170 welded thereto in the region of the first housing end face 140 than in the embodiment illustrated in Fig. 1. In adaptation to this, the first end face 140 of the energy storage cell 300 is closed off by a metallic disk 280. To connect the metallic disk 280 to the edge of the wound housing shell 200, laser welding can be performed from above in the corresponding edge regions, as indicated by the arrows.

[0224] In the area of ​​the second housing end face 150, the metal foil layers forming the housing shell 200 are connected and sealed by laser welding across the entire material thickness of the housing shell 200, as in the embodiment of the energy storage cell 100 in Fig. 1.

[0225] A preferred structure of the electrode-separator assembly 104 is illustrated in Fig. 3. The assembly 104 comprises the strip-shaped anode 105 with the strip-shaped anode current collector 106, which has a first longitudinal edge 106a and a second longitudinal edge parallel thereto. The anode current collector 106 is a foil made of, for example, copper or nickel. This comprises a strip-shaped main region loaded with a layer of negative electrode material 107, as well as a free edge strip 106b extending along its first longitudinal edge 106a and not loaded with the electrode material 107.

[0226] The electrode-separator assembly 104 further comprises the strip-shaped cathode 108 with the strip-shaped cathode current collector 109, which has a first longitudinal edge 109a and a second longitudinal edge parallel thereto. The cathode current collector 109 is, in particular, an aluminum foil. It comprises a strip-shaped main region loaded with a layer of positive electrode material 110, as well as a free edge strip 109b extending along its first longitudinal edge 109a and not loaded with the electrode material 110. Both electrodes are shown individually in the unwound state.

[0227] The anode 105 and the cathode 108 are arranged offset from one another within the electrode-separator assembly 104, so that the first longitudinal edge 106a of the anode current collector 106 extends from the first terminal end face 104a, and the first longitudinal edge 109a of the cathode current collector 109 extends from the second terminal end face 104b of the electrode-separator assembly 104. The offset arrangement is evident in the illustration at the bottom left. Also shown there are the two band-shaped separators 116 and 117, which separate the electrodes 105 and 108 from one another in the winding.

[0228] The illustration at the bottom right shows the electrode-separator assembly 104 in wound form, as it can be used in an energy storage cell according to Fig. 1 or Fig. 2 or in an energy storage cell according to Figs. 5A-C explained below. The electrode edges 106a and 109a extending from the end faces 104a and 104b are clearly visible. The winding jacket 104c is formed, for example, by several windings of the strip-shaped separators 116, 117 or, for example, by a plastic film.

[0229] Such an electrode-separator assembly 104 in the form of a coil is expediently produced on a winding machine. To facilitate contact with the components of the energy storage cell at the winding end, the uncoated edge regions of the electrode strips 105, 108 are preferably placed in a targeted manner toward the winding core.

[0230] The metallic disc or metallic cap 160 or a contact element 170, via which contact is made with the electrodes 105, 108, are preferably welded onto the winding end faces on the winding machine. This can be done particularly in the area of ​​the advantageously present beads 162, 171 on these elements, i.e., on the metallic disc or metallic cap or contact element.

[0231] Advantageously, these components on the winding end face have a central opening that can be used during positioning in the winding machine to guide these elements on a winding needle. This central opening can also be used for dosing an electrolyte.

[0232] In the case of a metallic cap with a circumferential sidewall, this cap is advantageously positioned so that the height of the circumferential sidewall is just below the width of the uncoated area of ​​the respective electrode strip. The diameter of the circumferential sidewall is comparable to the diameter of the coil. The height of the sidewall is comparable to the uncoated area of ​​the electrodes. The height of the sidewall can be, for example, between 1.5 and 2.5 mm.

[0233] The beads 162 of the metallic cap 160 or the beads 171 of the contact element 170 can be arranged in a star shape, for example, three beads per cap 160 or per contact element 170. In the center of the cap 160 or the contact element 170 there can be an opening or a hole that can be used to pass a winding needle through and thus to position these elements on the winding end faces.

[0234] Fig. 4 illustrates the structure of the electrode-separator assembly 104 with the housing shell wound around it as a cross-sectional view of an energy storage cell 100, 300 according to the invention. In the center of the spiral structure, the winding starts with a first band-shaped separator 117, a first electrode band, for example the negative electrode band 105, a second band-shaped separator 116 and the second electrode band, for example the positive electrode band 108. After a plurality of turns, the negative electrode band 105 ends first. The electrode material coating of the positive electrode band 108 ends in approximately the same area, with the uncoated cathode current collector 109 and the band-shaped separators 116 and 117 being continued for a few turns. Then the band-shaped separators 116 and 117 also end, so that only the cathode current collector 109 is continued for several turns.These last turns of the cathode current collector 109 alone form the housing shell 200. In this embodiment, the housing shell 200 is thus formed by an aluminum foil, provided that the cathode current collector 109 is an aluminum foil.

[0235] Analogously, the anode current collector, which consists of copper foil, for example, can be used to form the housing shell. In other embodiments, a separate foil can be used to form the housing shell 200. This foil can be a metal foil, a plastic foil, or a combination of both. During the production of the housing shell 200, the metal foil can thus come directly from the electrode coils as an uncoated current collector or be separately added within the winding machine. It is thus either directly connected to the electrode potential or already insulated.

[0236] The foil used to form the housing shell 200, in particular the metal foil used to form the housing shell 200, can be wound with the same or different thicknesses until the maximum outer diameter of the energy storage cell is reached. This foil forms the actual outer surface of the cell housing and replaces a housing cup used in conventional energy storage cells.

[0237] Advantageously, the winding machine can control the position of the overlap of the electrode strips and the strip-shaped separators. This makes it possible for the foil, in particular the metal foil, to be moved further toward the center of the end face during the formation of the housing shell. This allows for various designs of the housing shell 200. If the housing shell 200 is formed, for example, exclusively from aluminum foil, i.e., in particular, by extending the cathode current collector, the foil material can be moved back and forth between the anode and cathode sides, so that the end regions of the housing shell are thinner. Similarly, the housing shell can be formed with a copper foil, which is used, in particular, as a continuous section of the anode current collector for winding the housing shell.

[0238] In other embodiments, the housing shell may be formed from different foils, for example from different metal foils, for example from an aluminum foil and a copper foil.

[0239] The current collector foils can be cut to shape on the machine or in an upstream machine, if necessary, for example, if a wider foil needs to be narrowed at the end faces. Cutting the current collector foil or another foil forming the housing shell can be done, for example, using a laser, a punch, or a scissor cut. During the winding of the foil forming the housing shell, the first or, if necessary, all layers can be welded to the elements forming the housing end faces, in particular a metallic cap or metallic disc.

[0240] These processes create a winding body with a solid outer surface and end caps. Electrolyte can be metered through any holes or openings in the end caps, which are also used for the winding needles. These openings or holes can later be sealed, for example, with a blind rivet.

[0241] Particularly advantageously, the winding layers forming the housing shell 200 are glued together, ensuring the tightness of the housing shell. Conventional adhesives, such as liquid adhesive, can be used for this purpose. Alternatively, a plastic material can be sealed in. For such a seal, the corresponding sections of the foil strips can be pre-coated. If the housing shell 200 is formed, for example, by a terminal section of the current collector of an electrode strip, this terminal section, for example, the last few centimeters of the current collector strip, can be coated directly with a thermoplastic, so that a seal can later be applied over this thermoplastic.

[0242] A conventional energy storage cell with the 21700 form factor generally has a housing wall thickness of 0.25 mm and is made of nickel-plated steel, for example. To accommodate an electrode-separator assembly or the electrode winding in the housing cup, a clearance of approximately 0.2 mm in diameter is required, which remains unused for the electrode material. In the energy storage cell according to the invention with the wound housing shell, this unused space can be fully utilized. It is even possible that, to achieve particular stability of the housing shell in the cell according to the invention, the wall thickness of the foil layers forming the housing shell is greater than the usual wall thickness of 0.25 mm for a conventional cell, without reducing the capacity of the resulting cell.For example, the wall thickness of the energy storage cell according to the invention can be up to 0.35 mm, for example formed by 20 layers of aluminum foil, without the cell diameter increasing compared to a conventional energy storage cell and without the capacity being reduced. The assembly of a conventional energy storage cell, including the upstream production of the electrode-separator composite and cell assembly using a housing can, typically accounts for about one-third of the total production costs, of which about one-third is attributable to the production of the electrode-separator composite. Since the cell assembly line is eliminated in the production of the energy storage cell according to the invention, production costs can be significantly reduced, even if the winding process must be adapted to the inventive design of the housing shell using a foil.

[0243] As an alternative to the direct contacting of the electrode strips via the flat end-face elements of the energy storage cell, as illustrated in Figs. 1 and 2, i.e., in particular, directly via a metallic disc or cap on the housing end face or directly via a flat contact element (contact plate design), metallic contact strips can also be used to contact the electrodes in a conventional manner. It is particularly preferred if one of the electrodes, for example the cathode, is contacted via the flat contacting of the spiral edge of the uncoated cathode current collector emerging at the respective winding end face, and the anodic side of the electrode-separator assembly is contacted via a metallic contact strip.This contact strip can be welded, in particular perpendicular to the running direction of the corresponding electrode strip, to a free section of the strip-shaped current collector which is not loaded with electrode material and can emerge from the winding at the corresponding winding end face and be used for contacting.

[0244] The size or form factor of the energy storage cells according to the invention is, in principle, not limited. The height of the energy storage cell according to the invention, designed as a cylindrical round cell, is preferably in the range of 50 mm to 150 mm. Its diameter is preferably in the range of 15 mm to 60 mm. Cylindrical round cells with these form factors are particularly suitable for supplying power to electric drives in motor vehicles. However, smaller cylindrical round cells or button cells, for example, can also be readily produced according to the principle of the invention.

[0245] In addition to metallic foils, other strip-shaped substrates such as metallic or metallized nonwovens or open-pore metallic foams or expanded metals can in principle also be used as current collectors. In this case, the described preferred embodiment of the cell, in which the housing shell is formed by a terminal section of one of the current collectors, is generally unsuitable. However, the embodiment in which the housing shell is formed by a separate shell foil can also be readily implemented with such other strip-shaped substrates.

[0246] Fig. 5 illustrates, in sub-figures A, B, and C, further possible embodiments 400, 500, and 600 of an energy storage cell according to the invention. The energy storage cells 400, 500, and 600 each comprise a coil-shaped electrode-separator assembly 104. In contrast to the embodiments of an energy storage cell according to the invention illustrated in Figs. 1 and 2, the housing shell 200 of the energy storage cells 400, 500, and 600 is at least partially formed by a plastic film.

[0247] In the energy storage cell 400 shown in Fig. 5A, the electrical connection of the electrodes of the electrode-separator assembly 104 is realized by two metallic caps 460 located in the respective end regions of the energy storage cell 400. After the completion of the coil-shaped electrode-separator assembly 104, these metallic caps 460 are electrically connected, in particular welded, to the current collector strips of the electrodes forming the respective end faces of the coil. Subsequently, several plastic film layers 210 are wound over the outer circumference of the electrode-separator assembly 104 to form the housing shell 200. The housing can be sealed by welding the plastic film layers 210 to the end caps 460.

[0248] Fig. 5B shows a further embodiment of an energy storage cell 500 according to the invention. Here, the end faces of the electrode-separator assembly 104 are electrically contacted with metallic components 560, which each cover the end faces of the electrode-separator assembly and simultaneously form a terminal pin 570. The housing shell 200 is formed by plastic film layers 210 that are wound around the outside of the electrode-separator assembly 104. A plastic encapsulation 580 or a corresponding plastic perforated disk can be provided around the respective terminal pin 570, which flush seals the end faces of the energy storage cell 500 to the outside. The embodiment of an energy storage cell 600 illustrated in Fig. 5C has a housing shell 200, which is formed in the inner region by several layers of a metal foil 220 and in the outer region by several layers of a plastic film 210.For electrical contacting of the electrodes, a metallic cap 650 is provided on the lower end face of the electrode-separator assembly 104 in this illustration, and a metallic component 660 with a molded-on pole pin 670 is provided on the upper end face of the electrode-separator assembly 104. A circumferential insulating element 680, in particular a plastic encapsulation, encompasses both the outer edge of the metallic component 660 and the upper edge of the electrode-separator assembly in the region of its end face in order to electrically insulate the metallic component 660 from the other components of the energy storage cell 600. At the same time, the insulating element 680 flush seals the upper end face of the energy storage cell 600.

[0249] Fig. 6 shows a further particularly advantageous embodiment of the energy storage cell 700 according to the invention. The energy storage cell 700 is largely similar to the embodiment of the energy storage cell 300 illustrated in Fig. 2. Therefore, with regard to most of the described features, reference is made to the description of Fig. 2.

[0250] Compared to the embodiment of the energy storage cell 300 according to Fig. 2, the end face 150, which forms the positive pole of the cell, is designed somewhat differently in the energy storage cell 700. Specifically, the metallic cap 160 has a circumferential recess in its edge region, which is bounded on the outside by the side wall 165 of the cap 150 and on the inside by the beveled wall 166. The bounding walls 165, 166 form a channel or groove in the outer edge region of the metallic cap 160. This cavity formed can be used to apply a laser beam, indicated by the two oblique arrows, in such a way that the foil layers forming the housing shell 200 are welded through the side wall 165. This procedure for welding the housing shell 200 to the front side of the cell has proven to be particularly advantageous and practical.

Claims

PATENT CLAIMS Energy storage cell (100; 300; 400; 500; 600; 700) with a cylindrical, liquid-tight sealed housing having a first housing end face (140) and a second housing end face (150) and a housing jacket (200), with the following features: a. The cylindrical energy storage cell (100; 300; 400; 500; 600; 700) comprises an electrode-separator assembly (104) arranged in the housing; b. The electrode-separator assembly (104) is in the form of a cylindrical winding formed from electrode strips (105, 108) and at least one strip-shaped separator (116, 117), which has a first and a second terminal winding end face (120, 130) and a winding jacket; c.The electrode-separator assembly (104) is axially arranged in the housing such that the first winding end face (120) points towards the first housing end face (140) and the second winding end face (130) points towards the second housing end face (150); characterized by the following feature: d. The housing shell (200) of the energy storage cell is formed from at least one spirally wound film, preferably a spirally wound metal film, and comprises at least two layers of the film, preferably the metal film. Energy storage cell according to claim 1 with at least one of the following additional features: a. The electrode-separator assembly (104) comprises an electrode strip (108) with positive polarity, which includes a ribbon-shaped cathode current collector (109) having a first longitudinal edge and a second longitudinal edge parallel thereto, and coated on both sides with a positive electrode material (110); b.The electrode-separator assembly (104) comprises an electrode strip (105) with negative polarity, which includes a ribbon-shaped anode current collector (106) having a first longitudinal edge and a second longitudinal edge parallel to it. is coated on both sides with a negative electrode material (107); c. The at least one ribbon-shaped separator (116, 117) electrically isolates the oppositely polarized ribbon-shaped electrode strips (105, 108) from each other. Energy storage cell according to claim 2 with at least one of the following additional features: a. The spirally wound film forming the housing shell (200) of the energy storage cell is a spirally wound terminal section of the ribbon-shaped cathode current collector (109) that is not coated with the positive electrode material; b. The spirally wound film forming the housing shell (200) of the energy storage cell is a spirally wound terminal section of the ribbon-shaped anode current collector (106) that is not coated with the negative electrode material; c.The ribbon-shaped cathode current collector (109) and the ribbon-shaped anode current collector (106) have a substantially constant width over their entire length. Energy storage cell according to claim 1 or claim 2 with at least one of the following additional features: a. The spirally wound foil forming the housing shell (200) of the energy storage cell is a spirally wound shell foil strip, in particular a spirally wound shell foil strip wound onto the winding shell of the electrode-separator assembly (104); b. The winding shell of the electrode-separator assembly (104) is made of an electrically insulating material; c. The shell foil strip, in particular the shell metal foil strip, has a substantially constant width over its entire length. d. The sheath foil tape, in particular the sheath metal foil tape, has a greater width than the ribbon-shaped cathode current collector (109) and / or the ribbon-shaped anode current collector (106) of the electrode-separator assembly (104). Energy storage cell according to one of the preceding claims with one of the following additional features: a. The spirally wound foil forming the housing sheath (200) of the energy storage cell is made of aluminum or an aluminum alloy; b. The spirally wound foil forming the housing sheath (200) of the energy storage cell is made of copper or nickel or a copper alloy or a nickel alloy. c. The spirally wound foil forming the housing sheath (200) of the energy storage cell is made of plastic. Energy storage cell according to one of the preceding claims with the following additional feature: a.The layers formed from the foil, in particular the metal foil, which constitute the housing shell (200) of the energy storage cell, are bonded together by an adhesive layer arranged between the layers. Energy storage cell according to one of the preceding claims with at least one of the following additional features: a. At least one of the ribbon-shaped current collectors has at least one free section that is not coated with the electrode material and to which a metallic contact strip is welded; b. The metallic contact strip welded to the current collector protrudes from one of the winding end faces.

8. Energy storage cell according to one of the preceding claims with at least one of the following additional features: a. The first housing end face (140) of the energy storage cell is formed by a round, in particular circular, metal disc (280) or a metallic cap (180) comprising a round, in particular circular, base and a circumferential side wall (181); b. The metal disc (280) or cap (180) forming the first housing end face is connected to the housing shell (200) by welding; c. The second housing end face (150) of the energy storage cell is formed by a round, in particular circular, metal disc or a metallic cap (160) comprising a round, in particular circular, base and a circumferential side wall (161); d. The metal disc or cap (160) forming the second housing end face is connected to the housing shell (200) by welding.

9. Energy storage cell according to claim 8 in combination with claim 7 with the following additional feature: a. The metallic contact strip welded to the current collector is directly connected to the metal disc or cap forming the first housing end face or to the metal disc or cap forming the second housing end face, preferably by welding.

10. Energy storage cell according to claim 8 or claim 9 with at least one of the following additional features: a. An electrical contact pole (191) is guided through the first and / or through the second housing end face (140, 150), which is electrically insulated from the respective housing end face and which is electrically connected directly or via a metallic conductor to one of the ribbon-shaped current collectors (106; 109); b. One of the ribbon-shaped current collectors (106; 109) is electrically connected directly or via a metallic conductor to the metal disc or cap forming the first housing end face (140) or to the metal disc or cap (160) forming the second housing end face (150).

11. Energy storage cell according to any one of claims 2 to 10 with at least one of the following additional features: a. The ribbon-shaped anode current collector (106) comprises a main region loaded with a layer of the negative electrode material (107) and a free edge strip (106b) extending along its first longitudinal edge (106a) and not loaded with the negative electrode material; b. The ribbon-shaped cathode current collector (109) comprises a main region loaded with a layer of positive electrode material (110) and a free edge strip (109b) extending along its first longitudinal edge (109a) and not loaded with the positive electrode material; c.The electrode strips (105, 108) are arranged within the electrode-separator assembly (104) designed as a winding such that the first longitudinal edge (106a) of the anode current collector or the first longitudinal edge (109a) of the cathode current collector emerges from one of the terminal winding end faces, or that the first longitudinal edge (109a) of the cathode current collector emerges from one terminal winding end face and the first longitudinal edge (106a) of the anode current collector emerges from the other terminal winding end face of the electrode-separator assembly.

12. Energy storage cell according to claim 11 in combination with claim 8 with the following additional feature: a. One of the ribbon-shaped current collectors (106; 109) is directly connected to the The first housing end face (140) is electrically connected to the metal disc or cap forming the first housing end face (140) or to the metal disc or cap forming the second housing end face (150), wherein the first longitudinal edge of the respective current collector sits directly on the metal disc or the base of the cap and is welded to it, preferably over its entire length. Energy storage cell according to claim 11 or claim 12 with at least one of the following additional features: a. The first longitudinal edge (106a) of the anode current collector and / or the first longitudinal edge (109a) of the cathode current collector emerges from one of the terminal winding end faces and has a helical shape; b. At least the outermost turn of the first longitudinal edge is bent in the direction of a central axis of the electrode-separator assembly (104).Energy storage cell according to one of claims 2 to 13 in combination with claim 8 with at least one of the following additional features: a. The energy storage cell comprises at least one contact element (170), optionally including a separate electrical conductor fixed to the contact element, which is welded to the first longitudinal edge of the cathode current collector (109) or the anode current collector (106), preferably over its entire length, and via which this current collector is electrically connected to the metal disc or cap forming the first housing end face (140) or to the metal disc or cap forming the second housing end face; b. The contact element (170) sits flat on the first longitudinal edge of the cathode current collector or the anode current collector; c.The contact element comprises a first element that sits flat on the first longitudinal edge of the current collector emerging from the first or the second terminal end face and extends parallel to the respective winding end face, and comprises a second element that connects to the first element at an angle and extends over. the first element is electrically connected to the metal disc or cap forming the first housing end face or to the metal disc or cap forming the second housing end face; d. The contact element is directly connected to the metal disc or cap forming the first housing end face or to the metal disc or cap forming the second housing end face, in particular by welding; e. The contact element (170) is in direct contact or in contact via an electrical conductor with an electrical contact pole (191) extending through the first and / or the second housing end face. Energy storage cell (700) according to one of claims 8 to 14 with at least one of the following additional features: a.The metallic cap, which forms at least one of the housing end faces, has a circumferential recess, in particular an annular recess, in its edge region, which is bounded externally by the circumferential side wall of the metallic cap; b. The circumferential side wall of the metallic cap lies flat against the foil that forms the housing shell. Method for manufacturing an energy storage cell (100; 300; 400; 500; 600; 700) with a cylindrical, liquid-tight sealed housing having a first housing end face (140) and a second housing end face (150) and a housing shell (200) according to one of the preceding claims, comprising the following steps: a.An electrode-separator assembly (104) in the form of a winding with two terminal winding end faces and a winding jacket is produced on a winding machine, wherein the electrode-separator assembly is formed from electrode strips (105, 108) between which at least one band-shaped separator (116, 117) is arranged, wherein preferably the electrode strips each comprise a band-shaped current collector which is coated with electrode material; b. The housing shell (200) is formed by winding from a foil, in particular from a metal foil. Method according to claim 16 with the following additional feature: a. The housing shell (200) wound from foil is welded to at least one of the housing end faces (140, 150). Method according to claim 17 with at least one of the following additional features: a. The welding is carried out by laser welding; b. The welding is carried out such that a laser beam first penetrates the side wall of the metallic cap before striking the foil layers of the housing shell; c. At least one of the housing end faces is formed by a metallic cap with a circumferential recess according to the above description, wherein the recess is bounded on the outside by the side wall of the cap.

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