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

Abstract

An energy storage cell (100) is proposed in which a free edge strip (109a) of a cathode current collector (109) is welded to a contact element (112) of a lid assembly (102). Additionally, a method of manufacturing such an energy storage cell is proposed.

Description

[Technical Field]

[0001] The invention described below relates to energy storage cells and methods of manufacture. [Background technology]

[0002] Electrochemical energy storage elements can convert stored chemical energy into electrical energy through oxidation-reduction reactions. The simplest form of an electrochemical energy storage element is an electrochemical cell, which comprises a positive electrode and a negative electrode separated from each other by a separator. During discharge, electrons are released at the negative electrode as a result of an oxidation process. This generates an electronic current that can be drawn by an external power consumer, for which the electrochemical cell acts as an energy supplier. Simultaneously, an ionic current corresponding to the electrode reactions is generated within the cell. This ionic current crosses the separator and is enabled by an ion-conducting electrolyte.

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

[0004] Secondary lithium-ion cells are used today as energy storage elements for many applications because they can provide high currents and are characterized by relatively high energy density. They are based on the use of lithium, which can be transported back and forth in ionic form between the electrodes of the cell.

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

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

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

[0008] As an electrolyte, lithium-ion cells generally contain a solution of a lithium salt, such as lithium hexafluorophosphate (LiPF6), in an organic solvent (e.g., ethers and esters of carbonic acid).

[0009] When manufacturing lithium-ion cells, composite electrodes are generally combined with one or more separators to form an electrode-separator assembly. The electrodes and separators are often, but not necessarily, joined together under pressure, sometimes by lamination or adhesive bonding. The assembly can then be impregnated with an electrolyte to establish basic cell functionality.

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

[0011] For applications in the automotive sector, for electric bicycles or for other applications with high energy demands, such as in tools, lithium-ion cells with the highest possible energy density are required that are also capable of withstanding high currents during charging and discharging.

[0012] Cells for the above-mentioned applications are often formed as cylindrical round cells with a form factor of, for example, 21 x 70 (diameter * height in mm). This type of cell necessarily comprises an assembly in the form of a winding. Modern lithium-ion cells of this form factor can already achieve energy densities of up to 270 Wh / kg.

[0013] WO 2017 / 215900 A1 describes an electrode-separator assembly and a cylindrical circular cell in which the electrodes are formed as ribbon-like windings. Each electrode has a current collector on which an electrode material is mounted. Opposite polarity electrodes are offset from one another within the electrode-separator assembly, with the longitudinal edge of the positive electrode current collector projecting from the winding on one side and the longitudinal edge of the negative electrode current collector projecting from the winding on the other side. For electrical contact of the current collectors, the cell has a contact plate mounted on one end face of the winding and connected to one longitudinal edge of the current collector by welding. This allows electrical contact with the current collector, and therefore also with the associated electrode, over its entire length. This significantly reduces the internal resistance within the cell. As a result, large currents can be absorbed much better, and heat can also be dissipated better from the winding. Summary of the Invention [Problem to be solved by the invention]

[0014] Based on this prior art, it was desirable to further increase the energy density of energy storage cells, in particular of the type described in WO 2017 / 215900 A1. This object is achieved by an energy storage cell having the features of claim 1. A manufacturing method having the features of claim 10 is also an object of the invention. Preferred embodiments of the invention can be found in the dependent claims. [Means for solving the problem]

[0015] Cell according to the present invention An energy storage cell according to the present invention necessarily has the following characteristics a. to l: a. The cell comprises an electrode-separator assembly having an anode / separator / cathode arrangement. b. The anode of the electrode-separator assembly is ribbon-shaped and includes a ribbon-shaped anode current collector having a first longitudinal edge and a parallel second longitudinal edge. c. The ribbon-shaped anode current collector includes a main area bearing a layer of negative electrode material and a free edge strip extending along a first longitudinal edge thereof and not bearing a layer of negative electrode material. d. The cathode of the electrode-separator assembly is ribbon-shaped and includes a ribbon-shaped cathode current collector having a first longitudinal edge and a second longitudinal edge parallel thereto. e. the ribbon-shaped cathode current collector includes a main area bearing a layer of positive electrode material and a free edge strip extending along a first longitudinal edge thereof that is free of positive electrode material. f. The electrode-separator assembly is in the form of a cylindrical winding having first and second end faces and a winding shell therebetween, and includes an anode and a cathode in a spirally wound form. g. The ribbon electrode is formed and / or arranged in an electrode-separator assembly formed as a winding such that a free edge strip of the anode current collector or a free edge strip of the cathode current collector protrudes from the first terminal end face. h. The cell comprises an airtight and liquidtight housing that seals an interior space in which the electrode-separator assembly is disposed, the housing having a metal housing cup with a terminal circular opening, and a lid assembly with a circular edge that closes the circular opening. i. The lid assembly includes an annular seal of electrically insulating material surrounding the circular edge thereof. j. the housing cup includes, in axial order, a bottom, a center section, and a closure section; the central section is formed as a cylinder, and within the central section, a wound shell of the electrode-separator assembly, formed as a wound body, contacts the interior of the housing cup; Within the closure section, the annular seal is in pressure contact with the lid assembly and the interior of the housing cup. k. The lid assembly includes, from the inside to the outside, a metal contact element, a metal membrane electrically coupled to the metal contact element and configured to bulge or burst outward from a predetermined overpressure inside the housing, and a metal pole cap electrically coupled to the metal membrane. The energy storage cell according to the invention is particularly characterized in that: l. A free edge strip protruding from the first terminal end face of the electrode-separator assembly is welded to a contact element of the lid assembly.

[0016] The free edge strip protruding from the first end face can be a cathode current collector free edge strip or an anode current collector free edge strip. Preferably, it is a cathode current collector free edge strip.

[0017] In contrast to WO 2017 / 215900 A1, the energy storage cell according to the present invention has a contact element that is part of the lid assembly. Therefore, no separate electrical conductor is required between the lid and the contact element. Therefore, the energy storage cell according to the present invention is easy to manufacture. The absence of a separate conductor also means that the internal resistance of the energy storage cell can be reduced and that more useful volume is available in the housing, meaning that more active material can be introduced into the housing to increase the energy density.

[0018] Connection of one of the electrodes to the housing cup One of the electrodes of the energy storage element according to the invention is electrically coupled to the lid assembly via a free edge strip protruding from the first end face, while the other of the electrodes is preferably electrically coupled to the housing cup. Thus, the energy storage element according to the invention is preferably characterized by at least one of the following features, as shown immediately below: a. The ribbon electrodes are formed and / or arranged within an electrode-separator assembly formed as a winding such that one of the free edge strips of the anode current collector and the cathode current collector protrudes from a first terminal end face and the other of the free edge strips protrudes from a second terminal end face of the electrode-separator assembly. b. The other of the free edge strips protruding from the second terminal end face of the electrode-separator assembly is electrically coupled to the bottom of the housing cup.

[0019] Again, the free edge strip projecting from the first end face is preferably the free edge strip of the cathode current collector, and accordingly, the edge strip projecting from the second end face is preferably the free edge strip of the anode current collector.

[0020] The free edge strip projecting from the second terminal end face is particularly preferably welded to the bottom of the housing cup.

[0021] Alternatively, the edge strip can also be electrically connected to the bottom of the housing cup via a separate electrical conductor, for example a plate-like conductor, which can consist, for example, of nickel, copper, titanium, or a nickel, copper, or titanium alloy, or stainless steel, for example of type 1.4303 or 1.4404, or of type SUS304, or nickel-plated copper, especially if the edge strip protruding from the second end face is the free edge strip of the anode current collector.

[0022] Preferred construction of the lid assembly The lid assembly is generally applied in a pre-assembled form. In preferred embodiments, it is characterized by at least one of the following features a. to f.: a. The membrane is in direct contact with the contact element and is connected to it by welding. b. The membrane has a circular shape and therefore a circular edge. c. The contact element has a circular shape and therefore a circular edge. d. The contact element is welded to the center of the membrane. e. The contact element and the membrane have approximately the same diameter. f. The membrane and contact element are in electrical contact with each other only through the weld area in the center of the membrane.

[0023] Preferably, the immediately preceding features a, b, d, and f are implemented in combination. Preferably, all six immediately preceding features a to f are implemented in combination.

[0024] Preferably, the membrane is in direct contact with the polar cap. In a particularly preferred embodiment, the membrane is connected to the polar cap by welding.

[0025] Preferably, the polar cap externally closes off the lid assembly.

[0026] In further preferred embodiments, the lid assembly features at least one of the following features a. to c.: a. The annular seal seals against the circular edge of the metal contact element. b. The annular seal seals the circular edge of the metal membrane. c. An annular seal separates the circular edge of the metal membrane from the circular edge of the metal contact element.

[0027] Preferably, the immediately preceding features a., b. and c. are implemented in combination.

[0028] In a preferred embodiment of the energy storage cell according to the invention, the annular seal has several functions. First, it electrically isolates the lid assembly from the metal housing cup and simultaneously seals the housing. Second, it electrically isolates the metal contact elements from the metal membrane. For this purpose, it can have, for example, an F- or E-shaped cross section, as will be explained with reference to the drawings.

[0029] Preferred embodiments of the free edge strip protruding from the first distal end face Preferably, the energy storage cell according to the invention is characterized by at least one of the following characteristics a. to c.: a. The center section and the closure section are separated from each other by a radial indentation that circumferentially surrounds the exterior of the housing cup in an annular shape. b. The free edge strip protruding from the first terminal end face is wider than the distance d between the central section and the closed section, whereby the edge strip bridges the distance d and is in direct contact with the contact element. c. The distance d is defined by the upper and lower edges of the recess in the housing cup.

[0030] It is preferable that the immediately preceding features a and b, and preferably the immediately preceding features a to c, are realized in combination.

[0031] Particularly preferably, the energy storage cell according to the invention is characterized by at least one of the following characteristics a. and b.: a. The housing cup has the same maximum outer diameter in the center section and the closure section. b. In the region of the recess, the outer diameter of the housing cup is reduced by 4 to 20 times the wall thickness of the housing cup in this region.

[0032] Preferably, the immediately preceding features a. and b. are implemented in combination.

[0033] According to the above-described embodiment, the housing cup includes a recessed section between the central section and the closure section, in which the diameter of the housing cup decreases axially from a maximum to a minimum and then increases again to a maximum.

[0034] Preferably, the energy storage cell according to the invention is characterized by at least one of the following characteristics a. and b.: a. A free edge strip protruding from the first terminal end face of the electrode-separator assembly is compressed inwardly toward the center of the housing cup within the area of ​​the recess in the housing cup. b. In the region of the recess, an electrically insulating material is arranged between the interior of the housing cup and the free edge strip, electrically insulating the free edge strip from the potential of the housing cup. Preferably, the immediately preceding features a. and b. are implemented in combination.

[0035] Preferred housing shape The energy storage cell according to the invention is preferably a cylindrically round cell. Cylindrical round cells are known to have a cylindrical housing with a generally circular bottom. The housing cup of the energy storage cell according to the invention is typically formed by deep drawing. However, it is also possible to form the cup by welding the bottom into the tubular half.

[0036] Preferably, the height of the energy storage cells according to the invention formed as cylindrical round cells is in the range of 50 mm to 150 mm. Their diameter is preferably in the range of 15 mm to 60 mm. Cylindrical round cells with these form factors are particularly suitable for supplying electrical power to electric drives in motor vehicles.

[0037] As mentioned above, in the cell according to the invention, the winding shell of the electrode-separator assembly formed as a winding is in contact with the interior of the housing cup in the central section. Particularly preferably, it is in direct contact with the interior of the housing cup. In some embodiments, it may be provided that the interior is electrically insulated, for example by means of a film. In this case, the winding shell of the electrode-separator assembly is in contact with or rests against the foil-lined interior of the housing cup.

[0038] Particularly preferably, the housing cup has an opening edge within the closure section defining a circular opening that is bent radially inward to cover the edge of the lid assembly sealed by the seal and securely fix the lid assembly including the seal within the circular opening of the housing cup.

[0039] Preferably, the annular seal is compressed within the closure section, which is preferably pressed against the edge of the lid assembly from the interior of the housing cup.

[0040] Preferred material properties of the current collector, housing cup, and lid assembly The current collectors of the energy storage cell according to the invention have the function of making electrical contact over as large an area as possible with the electrochemically active components contained in the respective electrode materials, and preferably consist of a metal or at least are metallized on the surface.

[0041] In the case of a lithium-ion cell formed as the energy storage cell according to the present invention, suitable metals for the anode current collector are, for example, copper or nickel, or other electrically conductive materials, in particular alloys of copper and nickel, or metals coated with nickel. In particular, materials of type EN CW-004A or EN CW-008A having a copper content of at least 99.9% can be used as copper alloys. Alloys of type NiFe, NiCu, CuNi, NiCr, and NiCrFe are particularly suitable as nickel alloys. Stainless steels, such as type 1.4303 or 1.4404, or type SUS304, are also suitable.

[0042] In the case of lithium-ion cells formed as energy storage cells according to the present invention, aluminum or other conductive materials, including aluminum alloys, are particularly suitable as metals for the cathode current collector.

[0043] Suitable aluminum alloys for the cathode current collector are, for example, aluminum alloys of types 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 greater than 99.5%.

[0044] Preferably, the anode current collector and / or the cathode current collector are each a ribbon-shaped metal foil having a thickness in the range of 4 μm to 30 μm.

[0045] However, in addition to films, other ribbon-like substrates such as metal or metallized nonwovens, or open-pored metallic foams, or expanded metals can also be used as current collectors.

[0046] The current collector is preferably loaded on both sides with the respective electrode materials.

[0047] The housing cup is preferably made of aluminum, an aluminum alloy, or steel sheet, for example, nickel-plated steel sheet. Suitable aluminum alloys for the housing cup are, for example, Al alloys of types 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 greater than 99.5%.

[0048] The nature of the metal components of the lid assembly often depends on whether the free edge strip protruding from the first terminal end face is a cathode current collector free edge strip or an anode current collector free edge strip.

[0049] In the case where the free edge strip protruding from the first end face is the free edge strip of a cathode current collector, the metal contact element, and preferably also the metal film, is preferably made of the same or chemically similar material as the cathode current collector, i.e., in particular, aluminum or an aluminum alloy.

[0050] If the free edge strip protruding from the first end face is the free edge strip of an anode current collector, the metal contact element, and preferably also the metal film, is preferably made of the same or chemically similar material as the anode current collector, i.e., in particular copper or nickel, or a copper or nickel alloy, or stainless steel.

[0051] The pole covers are made of, for example, nickel-plated steel, or aluminum, or an aluminum alloy.

[0052] The annular seal preferably consists of an electrically insulating plastic material having a melting point >200° C., preferably >300° C. The plastic material is polyetheretherketone (PEEK), polyimide (PI), polyphenylene sulfide (PPS) or polytetrafluoroethylene (PTFE).

[0053] Electrodes and electrode materials In a particularly preferred embodiment, the energy storage cells according to the present invention are lithium-ion cells.

[0054] Essentially, all electrode materials known for secondary lithium-ion cells can be used for the electrodes of the energy storage cell.

[0055] Carbon-based particles, such as graphitic carbon or non-graphitic carbon materials capable of intercalating lithium, preferably also in particulate form, can be used as the active material in the anode. Alternatively, or in addition, lithium titanate (Li4Ti5O 12) Or its derivatives can also be contained in the anode, preferably also in the form of particles. Furthermore, the anode contains, as an active material, silicon, aluminum, tin, antimony, or a compound or alloy of these materials that can reversibly intercalate and redeposit lithium, for example, silicon oxide (especially, SiO x , where 0 < x < 2), and can optionally contain at least one material from the group in combination with a carbon-based active material. Tin, aluminum, antimony, and silicon can form intermetallic phases with lithium. The capacity for lithium receptacle is many times more than that of graphite or equivalent materials, especially in the case of silicon. Mixtures of silicon and carbon-based storage materials are often used. Thin anodes made of metallic lithium are also suitable.

[0056] Suitable active materials for the cathode include lithium metal oxide compounds such as LiCoO2 and LiFePO4, and lithium metal phosphate compounds. Lithium nickel manganese cobalt oxide (NMC) having the chemical formula LiNi x Mn y Co z O2 (where x + y + z is usually 1) is particularly suitable, lithium manganese spinel (LMO) having the chemical formula LiMn2O4, or lithium nickel cobalt aluminum oxide (NCA) having the chemical formula LiNi x Co y Al z O2 (where x + y + z is usually 1). Derivatives of these, for example, lithium nickel manganese cobalt aluminum oxide (NMCA) having the chemical formula Li 1.11 (Ni 0.40 Mn 0.39 Co 0.16 Al 0.05 ) 0.89 O2, or Li 1+x M-O compounds, and / or mixtures of the aforementioned substances can also be used. The cathode active material is also preferably used in particulate form.

[0057] In addition, the electrodes of the energy storage cell according to the present invention preferably contain an electrode binder and / or additives to improve electrical conductivity. The active material is preferably incorporated into the matrix of the electrode binder, and adjacent particles within the matrix are preferably in direct contact with each other. The conductive agent functions to increase the electrical conductivity of the electrode. Common electrode binders are, for example, based on polyvinylidene fluoride (PVDF), (Li-) polyacrylate, styrene butadiene rubber, or carboxymethyl cellulose, or mixtures of different binders. Common conductive agents are carbon black, fine graphite, carbon fibers, carbon nanotubes, and metal powders.

[0058] Preferred Materials for the Electrolyte and Separator The energy storage cell according to the invention preferably comprises a liquid electrolyte, in the case of a lithium-ion cell in particular an electrolyte based on at least one lithium salt, for example lithium hexafluorophosphate (LiPF6), present dissolved in an organic solvent (for example in a mixture of organic carbonates, or in a cyclic ether such as THF, or in a nitrile). Other lithium salts that can be used are, for example, lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(oxalato)borate (LiBOB).

[0059] Like the electrodes, the separators of the electrode-separator assembly of the energy storage cell of the present invention are preferably formed as ribbon separators. Alternatively, the electrode-separator assembly of the energy storage cell of the present invention includes more than one ribbon separator. For example, it may be preferable for a ribbon anode or ribbon cathode to be disposed between two ribbon separators.

[0060] The separator is preferably made of an electrically insulating plastic film. It preferably has pores so that it can be permeated by the liquid electrolyte. The plastic film can be made of, for example, polyolefin or polyetherketone. Nonwoven fabrics and fabrics made of plastic materials or other electrically insulating fabrics can also be used as separators. Separators having a thickness in the range of 5 μm to 50 μm are preferred.

[0061] However, the ribbon separator can also be a separator made of a solid electrolyte, which has inherent ionic conductivity and does not need to be impregnated with a liquid electrolyte. The solid electrolyte can be, for example, a polymer solid electrolyte based on a polymer-conducting salt complex, which exists in a single phase without any liquid component. The polymer matrix of the solid polymer electrolyte can be polyacrylic acid (PAA), polyethylene glycol (PEG), or polymethyl methacrylate (PMMA). Lithium conductive salts such as lithium bis(trifluoromethane)sulfonylimide (LiTFSI), lithium hexafluorophosphate (LiPF), and lithium tetrafluoroborate (LiBF) can be present therein.

[0062] Preferred shapes and dimensions of electrodes and separators The anode current collector, cathode current collector, and separator or separators of the cell according to the invention preferably each have the following dimensions: - Length in the range of 0.5m to 25m, - Width in the range of 40mm to 145mm.

[0063] In the electrode-separator assembly formed as a wound body, the ribbon-shaped anode, ribbon-shaped cathode, and ribbon-shaped separator or separators are preferably spirally wound. To fabricate the electrode-separator assembly, the ribbon-shaped electrode, preferably together with the ribbon-shaped separator, is fed to a winding device and preferably spirally wound around a winding axis in the winding device. In some embodiments, the electrode and separator are wound onto a cylindrical or hollow cylindrical winding core that rests on a winding mandrel for this purpose and remains within the wound body after winding.

[0064] The winding shell can be formed, for example, by a plastic film or an adhesive tape. It is also possible for the winding shell to be formed by one or more separator windings.

[0065] Preferably, the longitudinal edges of the separator or separators form the end faces of the electrode-separator assembly formed as a wound body.

[0066] It is further preferred that the free edge strip of the anode or cathode current collector protruding from the first terminal end face of the electrode-separator assembly has a maximum protrusion in the range of 10 mm to 15 mm, preferably 5 mm to 15 mm, more preferably 5 mm to 10 mm, more preferably 3 mm to 10 mm, and particularly preferably 3 mm to 8 mm, which protrusion corresponds approximately to the width of the edge strip and the distance d between the central section and the closed section.

[0067] It is further preferred that the free edge strip of the anode current collector or cathode current collector protruding from the second terminal end face of the electrode-separator assembly has a maximum protrusion in the range of 1 mm to 5 mm.

[0068] Preferably, the ribbon anode and ribbon cathode are offset from one another within the electrode-separator assembly to ensure that the free edge strip of the anode current collector projects from one of the terminal end faces and the free edge strip of the cathode current collector projects from the other terminal end face.

[0069] Preferred nominal capacity of the energy storage cell The lithium-ion-based energy storage cells according to the present invention, formed as cylindrical round cells, preferably have a nominal capacity of up to 15,000 mAh. In a 21x70 form factor, the lithium-ion energy storage cells according to one embodiment have a nominal capacity of 1,500 mAh to 7,000 mAh, with 3,000 to 5,500 mAh being particularly preferred. In an 18x65 form factor, the lithium-ion energy storage cells according to one embodiment have a nominal capacity of 1,000 mAh to 5,000 mAh, with 2,000 to 4,000 mAh being particularly preferred.

[0070] In the European Union, manufacturer information regarding the nominal capacity of secondary batteries is strictly regulated. For example, information regarding the nominal capacity of secondary nickel-cadmium batteries must be based on measurements in accordance with the IEC / EN 61951-1 and IEC / EN 60622 standards, information regarding the nominal capacity of secondary nickel-metal hydride batteries must be based on measurements in accordance with the IEC / EN 61951-2 standard, information regarding the nominal capacity of secondary lithium batteries must be based on measurements in accordance with the IEC / EN 61960 standard, and information regarding the nominal capacity of secondary lead-acid batteries must be based on measurements in accordance with the IEC / EN 61056-1 standard. All information regarding nominal capacity in this application is preferably based on these standards as well.

[0071] Preferred Embodiments of the Contact Element Covering the end faces of the electrode-separator assembly as extensively as possible, thus ensuring good contact of the current collectors, is important for the current-carrying capacity and thermal management of the energy storage cell of the present invention. The greater the coverage, the easier it is to contact the longitudinal edges of each current collector along its entire length. Therefore, heat generated within the electrode-separator assembly during charging or discharging can be easily dissipated through the contact elements or the bottom of the housing cup.

[0072] Preferably, the energy storage cell according to the invention is characterized by at least one of the following characteristics a. to h.: a. The longitudinal edges along which the free edge strips protruding from the first terminal end face of the electrode-separator assembly extend form a surface on which the contact elements lie flat or into which the contact elements are pressed. b. The contact element is dimensioned so that it covers at least 40%, preferably at least 60%, particularly preferably at least 80% of the first terminal end face. c. The contact element is a disk or a polygonal plate. d. The contact element has at least one aperture, in particular at least one hole and / or at least one slot. e. The contact element preferably has a uniform thickness in the range of 50 μm to 600 μm, preferably in the range of 150 μm to 350 μm. f. The contact element has two opposite planar surfaces and extends essentially in only one dimension. g. The contact element has at least one bead that appears as an elongated depression on one flat surface of the contact element and as an elongated ridge on the opposite flat surface, and the contact element is pressed with the flat surface having the elongated ridge into the surface formed by the longitudinal edge. h. the contact elements are welded to the longitudinal edges of the respective current collectors in the region of the bead, in particular via one or more weld seams arranged within the bead.

[0073] It is particularly preferred that the immediately preceding features a to d are realized in combination with one another. It is particularly preferred that all features a to h are realized in combination with one another.

[0074] In some embodiments, it has proven advantageous to pretreat the longitudinal edge of the current collector protruding from the first end face before the contact element is attached, in particular by folding in at least one recess in the longitudinal edge, corresponding to the at least one bead or elongated ridge described above on the flat surface of the contact element facing the first end face.

[0075] The longitudinal edges of the current collector may also be oriented by pre-treatment, for example, they may be bent in a predetermined direction.

[0076] At least one aperture in the contact element can be useful, for example, to allow the electrode-separator assembly to be immersed in the electrolyte, and further, pressure generated within the interior space of the cell can act on the membrane through the aperture.

[0077] Preferred Embodiments of Polar Caps Preferably, the energy storage cell according to the invention is characterized by the following feature a: a. One or more openings are formed in the center and / or on the edge of the polar cap.

[0078] Manufacturing Process The method according to the invention is used to manufacture an energy storage cell, the energy storage cell comprising an airtight and liquidtight sealed housing that seals an interior space in which an electrode-separator assembly is disposed as described above, the housing including a metal housing cup with a terminal circular opening, and a lid assembly with a circular edge that closes the circular opening. Regarding preferred features of the housing and the lid assembly, reference is made to the above.

[0079] In a preferred embodiment, the method is used to manufacture the energy storage cells described above.

[0080] The method is characterized by the steps a. to e. immediately below: a. An electrode-separator assembly as defined in claim 1 is provided, the electrode-separator assembly having a housing cup with a circular opening in a circular shape, and a first end surface and a second end surface. b. Inserting the electrode-separator assembly into the housing cup through the circular opening in the housing cup, second end first. c. Before or after step b., a metallic contact element, in particular a contact element as described above, is placed on the first end face and fixed by welding. d. Before or after step b., membranes and polar caps, in particular the membranes and polar caps described above, are placed on the contact elements either one after the other or as a pre-assembled assembly to form a lid assembly. e. Before or after step b., but in any case after step d., a weld between the membrane and the contact element is formed.

[0081] Preferably, before step d., but if necessary after step d., the electrolyte is introduced into the housing cup.

[0082] The housing is preferably closed in step f. to form the radial recess as described above with respect to the energy storage cell of the present invention.

[0083] In principle, step e. can also be carried out after the closing in step f. However, step e. is preferably carried out before step f.

[0084] The housing is preferably closed by bending the edges of the opening defining the circular opening radially over the edges of the lid assembly sealed by the seal, thereby securely securing the lid assembly including the seal within the circular opening of the housing cup.

[0085] The radial recess is preferably made to allow axial pressure to be exerted on the cell housing from above when the opening edge is bent over.

[0086] In a further preferred embodiment, the radial recesses are formed as described in Figures 8A-C of EP 3916877 A1.

[0087] In a preferred embodiment, before or after step b., a membrane, annular seal, and polar cap, in particular the membrane, seal, and polar cap described above in relation to the cell of the present invention, are placed on the contact element, either sequentially or as a pre-assembled assembly, to form a lid assembly.

[0088] A current collector protruding from the second end face of the electrode-separator assembly can be secured to the bottom of the housing cup, for example, by welding through the bottom.

[0089] In a particularly preferred embodiment, in a further step g., height calibration of the cell to be fabricated is performed. This step can be performed, in particular, as part of the closing process (step f.) or immediately after the closing process. In such a situation, the protrusion of the free edge strip of the anode or cathode current collector protruding from the first end face of the electrode-separator assembly is important because it can be deformed by axial pressure. For example, after step f., the height of the cell can be calibrated by applying axial pressure to its cover side, which can cause compression of the protrusion. This is possible, in particular, if the above-mentioned electrically insulating material electrically insulates the protrusion from the potential of the housing cup in the region of the recess (see also claim 6, feature b.).

[0090] Further features and advantages of the invention are apparent from the claims and from the following description of preferred embodiments of the invention in conjunction with the drawings. The individual features can be realized individually or in combination with one another. The drawings show, in schematic form: [Brief explanation of the drawings]

[0091] [Figure 1] FIG. 1 is a cross-sectional view of one embodiment of an energy storage cell according to the present invention. [Figure 2] FIG. 2 is a cross-sectional detail of an embodiment of an energy storage cell according to the present invention. [Figure 3] FIG. 3 is an embodiment of an energy storage cell according to the invention in a cross-sectional detail view, in which a laser beam is directed through an opening in the polar cap onto the welding spot between the membrane and the contact element. [Figure 4] FIG. 4 shows an electrode-separator assembly and its components that are part of an energy storage cell according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0092] 1 and 2 show an energy storage cell 100 according to the present invention having an airtight and liquidtight housing including a metal housing cup 101 having a terminal circular opening, and a lid assembly 102 having a circular edge 102a closing the circular opening.

[0093] The lid assembly 102 further includes an annular seal 103 made of an electrically insulating material that surrounds its circular edge 102a and electrically insulates the housing cup 101 and the metal components of the lid assembly 102 from each other.

[0094] The housing cup 101 includes, in axial order, a bottom 101a, a center section 101b, and a closure section 101c, with the center section 101b being formed as a cylinder. Within the center section 101b, a wound shell 104c of the electrode-separator assembly 104, formed as a wound body, contacts the interior of the housing cup 101. Within the closure section 101c, the annular seal 103 is in pressure contact with the lid assembly 102 and the interior of the housing cup 101. Within the closure section 101c, the housing cup 101 has an opening edge 101d that is bent radially inward to cover the edge 102a of the lid assembly 102 sealed by the seal 103 and defines a circular opening that securely fastens the lid assembly 102, including the seal 103, within the circular opening of the housing cup 101. The central section 101c and the closed section 101d are separated from each other by a radial recess 101e that circumferentially surrounds the exterior of the housing cup 101.

[0095] The lid assembly 102 of this example includes, from the inside to the outside, a disk-shaped contact element 112, a circular metal membrane 114 that bulges or bursts outward from a predetermined overpressure inside the housing, and a pole cap 117. The contact element 112 is welded to the membrane 114, which is in turn welded to the pole cap 117, which closes the lid assembly 102 to the outside. If the membrane 114 bulges outward as a result of overpressure, which can act directly on the membrane 114 through an aperture in the contact element (not shown), electrical contact between the contact element 112 and the membrane 114 or pole cap 117 is broken. At very high pressures, the membrane 114 can even burst.

[0096] The electrode-separator assembly 104 has a first end surface 104a and a second end surface 104b with a winding shell 104c disposed therebetween. A preferred structure is shown in FIG. 4. It includes a ribbon-shaped anode 105 having a ribbon-shaped anode current collector 106 and a ribbon-shaped cathode 108 having a ribbon-shaped cathode current collector 109. The anode current collector 106 is preferably a foil made of copper or nickel. The cathode current collector 109 is preferably an aluminum foil. Both the anode current collector 106 and the cathode current collector 109 have first longitudinal edges 106a, 109a and second longitudinal edges, main regions 106b, 109b, and free edge strips 106c, 109c. The main regions 106b, 109b are loaded with a layer of electrode material—negative electrode material in the case of the anode, and positive electrode material in the case of the cathode. Free edge strips 106c, 109c extend along their respective first longitudinal edges and are not loaded with electrode material. Both electrodes are shown individually in an unwound state. Within the wound electrode-separator assembly 104, the anode and cathode are offset from one another such that the first longitudinal edge 109a of the cathode current collector 109 protrudes from the first end face 104a of the electrode-separator assembly 104. The first longitudinal edge 106a of the anode current collector 106 protrudes from the second end face 104b of the electrode-separator assembly 104. This is clearly visible in the lower right image. The offset arrangement can be seen in the lower left image. Also shown therein are two ribbon-like separators 111a and 111b which separate the electrodes 105 and 108 from each other within the winding. The winding shell 104c is typically made of a plastic film.

[0097] 1 and 2, the free edge strip 109c is welded to the contact element 112 via the first longitudinal edge 109a of the cathode current collector 109 and is preferably in direct contact with the contact element 112 along its entire length. The contact element covers the first terminal end face 104a of the electrode-separator assembly 104 and lies flat on the first longitudinal edge 109a of the cathode current collector 109. On the other hand, the first longitudinal edge 106a of the anode current collector 106 is welded directly to the bottom 101a of the housing and is preferably in direct contact with the bottom 101a along its entire length.

[0098] This design of the energy storage cell 100 may eliminate a separate conductor connecting the contact element 112 to the lid assembly.

[0099] The central section 101b and the closed section 101c are separated from each other by a radial recess 101e that externally and circumferentially surrounds the housing cup 101. A free edge strip 109c protruding from the first terminal end face 104a is wider than the distance d between the central section 101b and the closed section 101c, such that the edge strip 109c bridges the distance d and is in direct contact with the contact element 112. The distance d is here defined by an upper edge 101f and a lower edge 101g that mark the beginning and end of the recess 101e.

[0100] Because the electrode-separator assembly 104, formed as a winding, is wider than the available space in the area of ​​the recess 101e, the free edge strip 109c of the cathode current collector 109 is compressed inward within the area of ​​the recess 101e towards the center of the housing cup 101. To prevent a short circuit from occurring, an electrically insulating material 115 is applied inside the recess 101e, which electrically insulates the free edge strip 109c of the cathode current collector 109 from the potential of the housing cup 101.

[0101] The energy storage cell 100 typically has a height in the range of 60 mm to 120 mm, and its diameter is preferably in the range of 20 mm to 50 mm. The housing cup 101 typically has a wall thickness in the range of 0.1 mm to 0.3 mm in the central section 101b.

[0102] The energy storage cell 100 shown in FIG. 3 differs from that in FIGS. 1 and 2 only in that a laser beam 119 is shown guided through an opening 117a in the pole cap 117 to form a weld between the contact element 112 and the membrane 114.

Claims

1. An energy storage cell (100) having the following characteristics: a. the cell (100) comprises an electrode-separator assembly (104) having an anode (105) / separator (111a, 111b) / cathode (108) arrangement; b. the anode (105) of the electrode-separator assembly (104) is ribbon-shaped and includes a ribbon-shaped anode current collector (106) having a first longitudinal edge (106a) and a second longitudinal edge parallel thereto; c. the ribbon-shaped anode current collector (106) includes a main area (106b) bearing a layer of negative electrode material (107), and a free edge strip (106c) extending along its first longitudinal edge (106a) and not bearing said negative electrode material; d. the cathode (108) of the electrode-separator assembly (104) is ribbon-shaped and includes a ribbon-shaped cathode current collector (109) having a first longitudinal edge (109a) and a second longitudinal edge parallel thereto; e. the ribbon-shaped cathode current collector (109) comprises a main area (109b) bearing a layer of positive electrode material (110), and a free edge strip (109c) extending along its first longitudinal edge (109b) and not bearing said positive electrode material (110); f. the electrode-separator assembly (104) is in the form of a cylindrical winding having a first end face (104a) and a second end face (104b) and a winding shell (104c) disposed therebetween, and contains the anode (105) and the cathode (108) in a spirally wound configuration; g. the anode (105) and the cathode (108) are formed and / or arranged within the electrode-separator assembly (104) formed as a winding such that the free edge strip (109c) of the cathode current collector (109) or the free edge strip (106c) of the anode current collector (106) protrudes from the first end surface (104a); h) the cell (100) includes a metal housing cup (101) that is closed in an airtight and liquid-tight manner, enclosing an internal space in which the electrode-separator assembly (104) is disposed, the housing cup (101) having a terminal circular opening, and a lid assembly (102) having a circular edge (102a) that closes the circular opening; i. said lid assembly (102) including an annular seal (103) of electrically insulating material surrounding a circular edge (102a) thereof; j. the housing cup (101) comprises, in axial order, a bottom (101a), a central section (101b), and a closure section (101c); the central section (101b) is formed as a cylinder, and within the central section (101b) the winding shell (104c) of the electrode-separator assembly (104) formed as a winding is in contact with the interior of the housing cup (101); - in the closed section (101c), the annular seal (103) is in pressure contact with the lid assembly (102) and the interior of the housing cup (101); and k. The lid assembly (102) includes, from the inside to the outside, a metal contact element (112), a metal membrane (114) electrically coupled to the contact element (112) and configured to bulge or burst outward from a predetermined overpressure inside the housing, and a metal pole cap (117) electrically coupled to the metal membrane (114); and l. An energy storage cell (100), characterized in that the free edge strip (106c or 109c) protruding from the first terminal end face (104a) is welded to the contact element (112) of the lid assembly (102).

2. Additional features include: the ribbon electrodes (105, 108) are formed and / or arranged within the electrode-separator assembly (104) formed as a winding such that one of the free edge strips (106c, 109c) of the anode and cathode current collectors protrudes from the first terminal end surface (104a) and the other of the free edge strips protrudes from the second terminal end surface (104b) of the electrode-separator assembly (104); b. the other of the free edge strips protruding from the second end surface (104b) of the electrode-separator assembly (104) is electrically coupled to the bottom (101a) of the housing cup (101); 10. The energy storage cell of claim 1, comprising at least one of:

3. Additional features include: a. said membrane (114) is in direct contact with said contact element (112) and is connected thereto by welding; b. said membrane (114) has a circular shape and therefore a circular edge; c. said contact element (112) has a circular shape and therefore has circular edges; d. said contact element (112) being welded to the center of said membrane (114); e. said contact element (112) and said membrane (114) having approximately the same diameter; f. said membrane (114) and said contact element (112) being in electrical contact with each other only through a welded area in said center of said membrane (114); 3. The energy storage cell of claim 1, wherein the first electrode is a conductor.

4. Additional features include: a. said annular seal (103) surrounding said circular edge of said contact element (112); b. said annular seal (103) surrounding said circular edge of said membrane (114); c. said annular seal (103) separating said circular edge of said membrane (114) from said circular edge of said contact element (112); The energy storage cell according to any one of claims 1 to 3, comprising at least one of:

5. Additional features include: a. the central section (101b) and the closed section (101c) are separated from each other by a radial recess (101e) circumferentially surrounding the exterior of the housing cup (101); b. the free edge strip (106c or 109c) protruding from the first distal end face (104a) is wider than the distance d between the central section (101b) and the closed section (101c), such that the edge strip (106c or 109c) bridges the distance d and is in direct contact with the contact element (112); c. the distance d is defined by the upper edge (101f) and the lower edge (101g) of the recess (101e) of the housing cup (101); The energy storage cell according to any one of claims 1 to 4, comprising at least one of:

6. Additional features include: a) the free edge strip protruding from the first distal end surface (104a) of the electrode-separator assembly (104) is compressed inwardly toward the center of the housing cup (101) within the area of ​​the recess (101e) of the housing cup (101); b) an electrically insulating material (115) disposed within the region of the recess (101e) between the interior of the housing cup (101) and the free edge strip protruding from the first terminal end surface (104a) of the electrode-separator assembly (104) for electrically insulating the free edge strip from the electrical potential of the housing cup (101); 6. The energy storage cell of claim 5, comprising at least one of:

7. Additional features include: a. the housing cup (101) has the same maximum outer diameter in the central section (101b) and the closed section (101c); b. in the region of the recess (101e), the outer diameter of the housing cup (101) is reduced by 4 to 20 times the wall thickness of the housing cup (101) in this region; The energy storage cell according to any one of claims 1 to 6, comprising at least one of:

8. Additional features include: the longitudinal edges (106a, 109a) along which the free edge strips extending from the first terminal end surface (104a) of the electrode-separator assembly (104) extend form a surface on which the contact element (112) lies flat or into which the contact element (112) is pressed; b. the contact element (112) is dimensioned so that it covers at least 40%, preferably at least 60%, particularly preferably at least 80% of the first terminal end face (104a); c) the contact element (112) is a disk or a polygonal plate; d. said contact element (112) has at least one aperture, in particular at least one hole and / or at least one slot; e. said contact element (112) preferably has a uniform thickness in the range of 50 μm to 600 μm, preferably in the range of 150 μm to 350 μm; f. said contact element (112) having two opposite planar faces and extending in essentially only one dimension; g. said contact element (112) having at least one bead appearing as an elongated depression on one flat surface of said contact element (112) and as an elongated ridge on the opposite flat surface, said contact element (112) being pressed with said flat surface having said elongated ridge into said surface formed by said longitudinal edges (106a, 109a); h) the contact elements (112) are welded to the longitudinal edges (106a, 109a) of the respective current collectors in the region of the bead, in particular via one or more weld seams arranged within the bead; The energy storage cell according to any one of claims 1 to 7, comprising at least one of:

9. Additional features include: a. one or more openings (117a) formed in the center and / or at the edge of said polar cap (117); The energy storage cell according to any one of claims 1 to 8, comprising at least one of:

10. A method for manufacturing an energy storage cell having the features of any one of claims 1 to 9, comprising the following steps: a. providing an electrode-separator assembly, as defined in claim 1, having a housing cup with a circular opening, and a first end surface and a second end surface; b. inserting the electrode-separator assembly into the housing cup through the circular opening in the housing cup, second end first; c. before or after step b., a metallic contact element is placed on the first end surface and secured in place by welding; d. placing a membrane and a polar cap over the contact element to form the lid assembly; e. forming a weld between the membrane and the contact element; A method comprising:

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