Energy storage element and method for manufacturing an energy storage element

Abstract

The invention relates to an energy storage element having a housing comprising a metal housing cup and a cover assembly. An electrode membrane composite having a sequence of anodes / membranes / cathodes / membranes is arranged in the housing cup. The electrode comprises a current collector having a band-shaped main region attached with a layer of electrode material and a free edge strip not attached with the electrode material and comprising a first longitudinal edge of the current collector, where the free edge strip leaves from the end side of the end of the electrode separator composite and forms an overhang on the end side. The contact piece member is supported on the overhang portion of the current collector and covers the end side of the end portion of the electrode separator composite and is connected to the overhang portion. The overhang portion connected to the contact piece member is an overhang portion compressed in the axial direction. The housing cup is designed to be devoid of a tool engagement structure. The invention further relates to a method for producing an energy storage element of this type.

Description

Technical Field

[0001] This invention relates to an energy storage element having a) A housing that defines the longitudinal axis and internal space of the energy storage element and includes a metallic housing cup and a cover assembly that closes the housing cup. b) A sealing assembly with a seal that radially surrounds the cover assembly and seals relative to the housing cup-shaped member, wherein the seal is compressed against the cover assembly through a free end section of the housing cup-shaped member that is radially bent inward. c) An electrode-diaphragm composite having an anode / diaphragm / cathode / diaphragm sequence, wherein the electrode-diaphragm composite is disposed within a cup-shaped housing and is in the form of a cylindrical wound body, wherein c1) The anode includes an anode current collector having a strip-shaped main region and free side strips. The strip-shaped main region is attached with a layer of negative electrode material, and the free side strips are not attached with electrode material and include a first longitudinal edge of the anode current collector, wherein the free side strips separate from the first end side of the electrode diaphragm composite and form an overhang on the first end side. c2) The cathode includes a cathode current collector having a strip-shaped main region and free side strips. The strip-shaped main region is attached with a layer of positive electrode material, and the free side strips are not attached with electrode material and include a first longitudinal edge of the cathode current collector, wherein the free side strips separate from the second end side of the electrode diaphragm composite and form an overhang on the second end side. d) Contact piece components, contact piece components d1) Supported on the overhang of the anode current collector and covering the first end side of the electrode diaphragm composite and connected to the overhang; or d2) Located on the overhang of the cathode current collector and covering the second end side of the electrode diaphragm composite and connected to the overhang.

[0002] Furthermore, the present invention relates to a method for manufacturing such an energy storage element, comprising the steps of: (A) A housing with a metal cup-shaped shell and a lid assembly; (B) Provide a sealing assembly with a seal and a support ring; (C) Provide an electrode-diaphragm composite; (D) Connecting the contact piece to the edge strip of the anode current collector or the edge strip of the cathode current collector, especially by welding them together; (D) Position the seal and support ring; (F) Connect the cover assembly to the contact piece component; (G) Closed shell cup-shaped component. Existing technology Energy storage elements of the type described at the beginning are, for example, described in the applicant’s European patent application number 23190399.8.

[0003] Electrochemical energy storage elements convert stored chemical energy into electrical energy through redox reactions. The simplest form of an electrochemical energy storage element is an electrochemical cell (hereinafter also referred to as an energy storage cell). An electrochemical cell consists of a positive electrode and a negative electrode interconnected by an electrolyte that conducts ions. A diaphragm can be arranged between the electrodes for electrostatic separation. During discharge, electrons are released at the negative electrode through an oxidation process. This generates an electron flow that can be intercepted by an external electrical load; therefore, the electrochemical cell serves as the energy supply for this load. Simultaneously, an ion flow corresponding to the electrode reactions occurs within the cell via the ion-conducting electrolyte.

[0004] An energy storage device may include one or more electrochemical cells, such as two or more energy storage cells connected in parallel or series. Such an energy storage device with multiple cells is also called a battery.

[0005] If the described discharge is reversible, meaning there is a possibility of reversing the chemical energy to electrical energy conversion that occurred during discharge and thereby recharging the cell, it is called a secondary cell. In secondary cells, the usual designation of the negative electrode as the anode and the positive electrode as the cathode generally relates to the discharge function of the electrochemical cell.

[0006] Currently, rechargeable lithium-ion cells are used in a variety of applications as energy storage devices because they can provide high current and are distinguished by their relatively high energy density. The basis of rechargeable lithium-ion cells is the use of lithium, which can migrate back and forth between the electrodes of the cell in ionic form. 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.

[0007] As the electrochemical active component (active material) for secondary lithium-ion battery cells, in principle, any material capable of absorbing and re-releasing lithium ions can be considered. For the negative electrode, carbon-based particles such as graphite carbon are used, for example. As the active material for the positive electrode, lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium iron phosphate (LiFePO4), or their derivatives can be used, for example. Electrochemical active materials are typically contained in the electrode in particulate form.

[0008] As an electrochemically inactive component, composite electrodes typically include planar and / or strip-shaped current collectors (e.g., metal foils) that serve as a carrier for the corresponding active material. The current collector for the negative electrode (anode current collector) may be formed, for example, from copper or nickel, and the current collector for the positive electrode (cathode current collector) may be formed, for example, from aluminum.

[0009] In addition, as an electrochemically inactive component, the electrode may include an electrode binder (such as polyvinylidene fluoride (PVDF) or other polymers, such as carboxymethyl cellulose), additives to improve conductivity, and other additional materials. The electrode binder ensures the mechanical stability of the electrode and often also ensures the adhesion of the active material to the current collector.

[0010] As an electrolyte, lithium-ion cells typically include a solution of lithium salts, such as lithium hexafluorophosphate (LiPF6) in an organic solvent (e.g., carbonates and ethers).

[0011] Typically, in the manufacture of lithium-ion cells, composite electrodes are combined with one or more separators to form an electrode-separator composite. Here, the electrodes and separators are mostly (but not necessarily) connected to each other under pressure, and if necessary, through lamination or bonding. Subsequently, the basic functions of the cell can be established by wetting the composite with an electrolyte.

[0012] In various embodiments, and also in this invention, the electrode-diaphragm composite is formed as a wound body, or the electrode-diaphragm composite is processed into a wound body. In a first case, for example, strip-shaped positive and negative electrodes and at least one strip-shaped diaphragm are fed separately to a winding machine and spirally wound in the winding machine to form a wound body having a positive electrode / diaphragm / negative electrode sequence. In a second case, the strip-shaped positive and negative electrodes and at least one strip-shaped diaphragm are first combined into an electrode-diaphragm composite body, for example, when the aforementioned pressure is applied. Subsequently, the composite body is wound in another step.

[0013] For applications in the vehicle sector, such as electric bicycles, or other applications with high energy demands (like those in tools), lithium-ion cells with the highest possible energy density are required, which can be loaded with high currents during both charging and discharging.

[0014] Energy storage cells for these applications, having an electrode-diaphragm composite in the form of a wound structure, are designed as cylindrical cells, typically with a length or height between 50 mm and 150 mm and a diameter between 15 mm and 60 mm. For example, modern lithium-ion cells with dimensions of 21 × 70 (diameter multiplied by height in mm) can achieve energy densities up to 270 Wh / kg.

[0015] The volume fraction of the internal space available for the winding body is particularly important for the capacity and power of an energy storage cell. With the dimensions and components of the energy storage cell remaining constant except for the winding body, a larger volume allows for a correspondingly larger winding body to be arranged within that volume, resulting in a greater capacity and power for the energy storage cell. Summary of the Invention

[0016] The object of the present invention is to provide an energy storage element, particularly an energy storage cell, taking into account this idea, and to provide a method adapted thereto.

[0017] In energy storage elements, this objective is achieved in the following ways. e) The protrusion connected to the contact piece component is a protrusion that is compressed in the axial direction; f) The housing cup-shaped part is designed to have a tool-free joint structure.

[0018] Preferably, the housing cup-shaped component includes a circular bottom and sidewalls, and a circular end opening closed by a cover assembly.

[0019] Preferably, the cup-shaped housing of the energy storage element according to the invention comprises, in axial order, a bottom, a central section formed by sidewalls, and a closed section. In a preferred embodiment, at least one of the following features is applicable: - The central section is designed as a hollow column.

[0020] - In the central section, the sleeve of the electrode diaphragm composite, which is designed as a cylindrical winding, contacts the inner side of the cup-shaped housing.

[0021] - The radially inwardly curved end section of the cup-shaped housing defines a circular opening.

[0022] - The cover assembly includes a seal (which is preferably designed to be annular) that is locked in place by a radially inwardly curved end section into a circular opening in the cup-shaped part of the housing.

[0023] In constructing the accumulator element described at the beginning, a conventional crimping process is employed to seal the cup-shaped housing via a cover assembly. In this process, the initially cylindrical, free end section of the cup-shaped housing is radially bent inwards onto the area of ​​the cover assembly, thereby compressing the seal. Details will be explained later.

[0024] At this point, the wound material is already located within the cup-shaped housing. Furthermore, to avoid damage to the wound material during the crimping process, known accumulator elements incorporate a tool engagement structure within the cup-shaped housing. The function of this tool engagement structure is to allow a portion of the crimping tool to be attached to the housing when the cup-shaped housing is closed via the crimping process. During closure, a reverse tool, which is part of the crimping tool, engages with the tool engagement structure. As part of the reverse process, this reverse tool supports the cup-shaped housing in the axial direction to counteract the forces acting during the crimping process and dissipates the forces, thereby keeping the wound material substantially unaffected by forces. Typically, a circumferentially encircling groove is provided in the cup-shaped housing for this purpose during closure; this groove remains after the accumulator element is manufactured.

[0025] Since the groove extends radially into the interior space of the housing relative to the rest of the wall of the housing cup, the area in which the groove is constructed cannot be used for the winding body, because the winding body completely fills the housing cup in the radial direction.

[0026] For example, the applicant’s European patent application No. 23202968.6 describes bending the edge strip with the aim of making the radius of the contact piece component significantly smaller than the diameter of the winding body, so as to reduce the risk of the contact piece component contacting the housing.

[0027] However, according to the present invention, it has been recognized that a wound body whose edge strip connected to the contact piece is bent or compressed, folded, or otherwise deformed in the axial direction, and generally speaking, a wound body with an overhang compressed in the axial direction, can withstand the forces generated when the cup-shaped part of the closed housing is closed without negatively affecting the function of the accumulator element. It has been further recognized that no further support is needed to counteract the forces generated during closure, and the tool engagement structure can be eliminated.

[0028] This frees up space in the axial direction for the winding, allowing the energy storage element, especially the energy storage cell, to have a larger axially extended winding in the main regions of the anode and cathode, while keeping other internal dimensions unchanged. Since the main regions carry electrode material, this directly increases the capacity and power of the energy storage element.

[0029] In a preferred embodiment, a strip-shaped diaphragm is used for the electrode-diaphragm composite, the strip-shaped diaphragm being slightly wider than the electrodes of the wound body. Preferably, the longitudinal edge of the diaphragm is located in a plane and preferably forms the end side of the wound body.

[0030] Furthermore, preferably, in its undeformed state, i.e., before axial compression of the protruding portion, the free edge of the current collector, which exits from the end side of the winding or from the side of the stack, extends no more than 5500 µm from that end side or side, and preferably no more than 4000 µm. Therefore, before axial compression, the height of the protruding portion of the free edge is preferably a maximum of 5500 µm, and particularly preferably a maximum of 4000 µm. This is especially applicable to cells of the 21700 specification (21 mm diameter, 70 mm height).

[0031] Particularly preferably, before the protruding portion is compressed axially, the free edge of the anode current collector extends no more than 3000 µm from the end of the winding body, and more preferably no more than 2000 µm. Particularly preferably, the free edge of the cathode current collector extends no more than 4000 µm from the end of the winding body, and more preferably no more than 3000 µm. Therefore, before axial compression, the height of the protruding portion of the free edge of the anode current collector is preferably a maximum of 3000 µm, and more preferably a maximum of 2000 µm. Therefore, before axial compression, the height of the protruding portion of the free edge of the cathode current collector is preferably a maximum of 4000 µm, and more preferably a maximum of 3000 µm.

[0032] Preferably, in the electrode diaphragm winding used within the scope of the present invention, the excess portion of the free edge strip departing from the first end side of the electrode diaphragm composite is compressed in the axial direction by a minimum of 10% and a maximum of 80%, preferably by 15% to 60%, and particularly preferably by 15% to 50% (relative to the height of the excess portion before compression).

[0033] Preferably, in the electrode diaphragm winding used within the scope of the present invention, the protruding portion of the free edge strip departing from the second end side of the electrode diaphragm composite is compressed in the axial direction by a minimum of 10% and a maximum of 80%, preferably by 15% to 60%, and particularly preferably by 15% to 50% (relative to the height of the protruding portion before compression).

[0034] Therefore, the uncompressed portion with a height of 3 mm can still have a height of, for example, 1.6 mm after compression.

[0035] The strip-shaped anode, strip-shaped cathode, and one or more strip-shaped diaphragms are preferably located in a composite designed as a wound body, spirally wound. To manufacture the composite, the strip-shaped electrode and the one or more strip-shaped diaphragms are preferably fed together to a winding apparatus and spirally wound about a winding axis in the winding apparatus. In several embodiments, the electrode and the one or more diaphragms are wound onto a cylindrical or hollow cylindrical winding core, which is supported on a winding mandrel and remains in the wound body after winding.

[0036] In this document, the tool engagement structure is defined as a structure within the sidewall of the cup-shaped housing, which allows the portion of the crimping tool to engage therein for the purpose of performing the crimping process, and in particular for performing the reverse process. For this purpose, the structure must have a minimum depth within the sidewall.

[0037] Such a tool engagement structure for the crimping process can exist, in particular, in the form of the grooves mentioned above, in the sidewalls, especially in annular recesses. However, it is also conceivable that multiple annularly arranged recesses in the sidewalls (e.g., 3, 4, 6, or 8 recesses) can serve as a tool engagement structure.

[0038] Conversely, this means that recesses in sidewalls with a depth less than the corresponding minimum depth are not within the scope of the term "tool engagement structure".

[0039] Therefore, the scope of protection of the invention according to claim 1 includes energy storage elements in which the sidewalls of the cup-shaped housing have no recesses. The scope also includes energy storage elements in which the sidewalls of the cup-shaped housing have one annular recess designed as a groove or multiple annularly arranged recesses, the depth of which is less than the minimum depth.

[0040] The minimum depth required for the crimping process is given under the following conditions: The depth of one or more annular recesses arranged in annular arrangement, which are designed as tool engagement structures, is preferably at least 7 times the wall thickness of the housing cup in the region of one or more recesses.

[0041] Conversely, this means that recesses with a depth less than 7 times the wall thickness of the housing cup-shaped member in one or more recessed areas are not, by definition, tool engagement structures in the sense of this application. More preferably, recesses with a depth less than 6 times, preferably less than 5 times, more preferably less than 4 times, also preferably less than 3 times, and particularly preferably less than 2 times, the wall thickness of the housing cup-shaped member in one or more recessed areas are not tool engagement structures in the sense of this application.

[0042] Regardless of the depth of any possible recesses, the tool engagement structure must always be functionally designed to interact with the engagement tool in the manner explained above.

[0043] A sealing technique for creating such shallow recesses is described in EP 3916877 A1. After the electrode diaphragm composite is pushed into a stepped cup-shaped housing, the stepped portion can be transformed into a surrounding recess by calibrating the outer diameter of the cup-shaped housing. This recess circumferentially surrounds the sidewall of the cup-shaped housing but does not have the depth required for a crimped recess.

[0044] Preferably, the cover assembly defines a closure plane, which is typically defined by a portion of the cover assembly facing the interior space of the housing. The smaller the axial distance between the main regions of the anode and cathode and the closure plane, the longer the axial length of the main region of the winding with electrode material can be installed, given the same outer dimensions of the housing. In the accumulator element according to the invention, the axial distance between the main regions of the anode and cathode and the closure plane can be between 0.6 mm and 3.0 mm, particularly between 0.8 mm and 2.5 mm, preferably between 1.0 mm and 2.0 mm, and more preferably between 1.2 mm and 1.6 mm.

[0045] More preferably, the cover assembly includes a surrounding outer closure ring, which is surrounded by a seal, wherein the closure plane is defined by the inner side of the closure ring facing the interior space of the housing.

[0046] In a particularly preferred embodiment, the cover assembly includes a metal disk, which is welded to the distance compensation structure in the connection area of ​​the distance compensation structure. a) Provided via a distance compensation piece connected to the contact piece; or b) Provided via contact piece components.

[0047] Therefore, in the latter case, the contact piece component includes a distance compensation structure. Thus, a separate distance compensation piece component is not required.

[0048] Conversely, the distance compensation plate component may have a contact area that serves as a contact plate component and is connected to the free edge of the anode current collector or the free edge of the cathode current collector.

[0049] The metal disk can provide CID functionality (CID = current interrupt device), which will be explained in more detail below.

[0050] Particularly preferably, the energy storage element is distinguished by at least one of the following features: a) A support ring is provided between the distance compensation plate component and the metal disk. The support ring is a separate component or is included in the seal. The support ring is in direct contact with the distance compensation plate component and the metal disk. b) The seal includes a support section, which is used to support the seal on the contact piece or in the area of ​​the distance from the compensation piece.

[0051] The support ring or support section provides a safety function, namely, it prevents the distance compensation plate component and / or contact plate component from lifting up along with the metal disc in the event of increased pressure within the housing, which is necessary for the aforementioned CID function.

[0052] For the purpose of providing CID functionality, the distance compensation structure may have a material weakening part, especially a groove, which encloses or even defines the connection area of ​​the distance compensation structure.

[0053] Furthermore, it is advantageous that the metal disc can be designed as a PRV (pressure relief valve) and, for this purpose, include material weakening sections, such as annular or circular weakening grooves.

[0054] The PRV will be explained in more detail below.

[0055] In this method, the above objective is achieved through the following steps: (H) Compress the edge strip in the axial direction or bend the edge strip, especially before or during step (D); (I) Perform steps (D), (E), (F), and (H) outside the shell cup-shaped part to form the cap winding composite; (K) Before performing step (G), the cap winding composite and the seal are installed into the housing cup.

[0056] According to the present invention, it has been recognized that eliminating the tool engagement structure advantageously enables the pre-forming of the cap winding composite into an assembly, which is then subsequently inserted into the housing cup-shaped part.

[0057] For variants of CID functionality and distance compensation structures, this is advantageous. (L) A distance compensation structure is provided by a distance compensation piece, and in step (F) the cover assembly is connected to the distance compensation structure and the distance compensation piece is connected to the contact piece; or (M) A distance compensation structure is provided through a contact piece component, and in step (F) the cover assembly is connected to the distance compensation structure. Attached Figure Description

[0058] Embodiments of the present invention will now be explained in more detail with reference to the accompanying drawings. Wherein: Figure 1 A longitudinal section of an energy storage cell according to the prior art is shown, the energy storage cell including a housing with a tool engagement structure in the form of a surrounding tool engagement groove; Figure 2 The electrode diaphragm composite and its components are shown; Figure 3 The energy storage cell according to the present invention is shown in the corresponding embodiment. Figure 1 The longitudinal section of the energy storage cell according to the present invention has a housing without the tooling structure according to the first embodiment; Figure 4 It shows that it has the following characteristics: Figure 3 The longitudinal section of the energy storage cell according to the present invention is a modified embodiment; Figure 5 The diagram shows a corresponding energy storage cell according to the second embodiment of the invention. Figure 1 Longitudinal section; Figure 6 The diagram shows a corresponding energy storage cell according to the invention in the third embodiment. Figure 1 Longitudinal section; Figure 7 The diagram shows a corresponding energy storage cell according to the fourth embodiment of the invention. Figure 1 The longitudinal section. Detailed Implementation

[0059] 1. Energy storage cell based on existing technology Figure 1 An exemplary energy storage element in the form of an energy storage cell 10 is shown, which has a basic structure known, for example, from the applicant’s European patent application No. 23190399.8 described above.

[0060] The energy storage cell 10 includes a gas- and liquid-sealed housing 102 that defines an internal space 102a and defines the longitudinal axis 10a of the energy storage cell 10. The housing 102 includes a metallic housing cup-shaped member 104 having a circular end opening 106. The housing cup-shaped member 104 includes, in the axial direction, a bottom 104a, a cylindrical central section 104b, and a closed section 104c.

[0061] Furthermore, the housing 102 includes a cover assembly 108 disposed within the enclosed section 104c and closing the opening 106. The cover assembly 108 includes a surrounding outer closure ring 110 extending transversely to the longitudinal axis 10a of the energy storage cell 10. Additionally, the energy storage cell 10 has a sealing assembly with an annular seal 112 made of electrically insulating material, which radially surrounds the cover assembly 108 and seals relative to the housing cup-shaped member 104. In this embodiment, the seal 112 surrounds the closure ring 110 of the cover assembly 108 and electrically insulates the housing cup-shaped member 104 and the cover assembly 108 from each other.

[0062] The closing plane 108a of the cover assembly 108 is defined by the inner side 110a of the closing ring 110 of the cover assembly 108 facing the inner space 102a of the housing 102.

[0063] The energy storage cell 10 includes an electrode diaphragm composite 114, which is housed within a cup-shaped housing 104, and... Figure 2 Its structure is shown in the figure.

[0064] The electrode diaphragm composite 114 includes a strip-shaped anode 116 having a strip-shaped anode current collector 118 having a first longitudinal edge 118a and a second longitudinal edge 118b parallel to the first longitudinal edge. The anode current collector 118 is a foil made of copper or nickel. The anode current collector 118 has a strip-shaped main region 120 and free side strips 124. The strip-shaped main region is attached with a layer composed of negative electrode material 122, and the free side strips include the first longitudinal edge 118a of the anode current collector 118 and are not attached with negative electrode material 122.

[0065] Furthermore, the electrode diaphragm composite 114 includes a strip-shaped cathode 126 having a strip-shaped cathode current collector 128, the cathode current collector having a first longitudinal edge 128a and a second longitudinal edge 128b parallel to the first longitudinal edge. The cathode current collector 128 is an aluminum foil. The cathode current collector 128 has a strip-shaped main region 130 and free side strips 134, the strip-shaped main region being coated with a layer composed of positive electrode material 132, and the free side strips including the first longitudinal edge 128a of the cathode current collector 128 and not coated with positive electrode material 132.

[0066] Figure 2 A and Figure 2 B shows either anode 116 or cathode 126 separately in their unwound state. Figure 2C illustrates an electrode-diaphragm composite 114 in the form of a wound body 136, similar to an electrode-diaphragm composite wound body that can be applied in an energy storage cell 10, wherein the anode 116 and cathode 126 are wound. Furthermore, the wound body 136 includes a first strip-shaped diaphragm 138 and a second strip-shaped diaphragm 140, which separate the anode 116 and cathode 126 from each other within the wound body 136. In this embodiment, a repeating sequence of anode 116 / diaphragm 138 / cathode 126 / diaphragm 140 is created in the wound body 136 in such a way that whether the sequence begins with the anode 116 or the cathode 126 depends on the outer layer. The wound body sleeve 136a is formed of a plastic film.

[0067] exist Figure 2 Diaphragm 138 and 140 can be seen in D. Furthermore... Figure 2 As shown in Figure D, the anode 116 and cathode 126 are arranged within the winding body 136 in such a way that the free strip 124 of the anode current collector 118 with the first longitudinal edge 118a leaves the first end side 114a of the electrode diaphragm composite 114, and the free strip 134 of the cathode current collector 128 with the first longitudinal edge 128a leaves the second end side 114b of the electrode diaphragm composite 114.

[0068] In this manner, the free side strip 124 of the anode current collector 118 forms an overhang 141a at the first end side 114a of the electrode diaphragm composite 114. Correspondingly, the free side strip 134 of the cathode current collector 128 forms an overhang 141b at the second end side 114b of the electrode diaphragm composite 114. At this time, both overhangs are shown in an uncompressed manner.

[0069] Therefore, end sides 114a and 114b are also the corresponding end sides of the winding 136. Figure 2 C shows the wound body 136 and its components in its winding configuration, in which, in particular, the strips 124 of the anode current collector 118 and the strips 134 of the cathode current collector 128, and the overhangs 141a and 141b formed by the free strips 124 and 134, are not subjected to force loading and extend freely in the axial direction relative to the wound body 136.

[0070] In the accumulator cell 10, the cathode current collector 128 of the winding 134 is preferably directly welded to the bottom 104a of the housing cup-shaped member 104 along its entire length using its free side strip 134. In other embodiments, the side strip 134 may be welded to a metal plate that is flatly supported on the side strip and electrically connected to the bottom 104, for example, also by welding.

[0071] The anode current collector 118 of the winding body 134 is connected to the contact piece component 142 by welding using its free edge strip 124. The contact piece component is supported on the free edge strip 124 of the anode current collector 118, especially on the first longitudinal edge 128a, by means of the annular contact area 142a, and covers the first end side 114a of the electrode diaphragm composite 114 or the winding body 136.

[0072] In one modification, the winding body 136 is also installed in the reverse manner. That is, in this case, the anode current collector 118 is welded to the bottom 104a of the housing cup-shaped member 104 by means of its free side strip 124, while the cathode current collector 128 is connected to the contact piece member 142.

[0073] The cover assembly 108 of the energy storage cell 10 includes an externally accessible electrode cap 144, which is electrically connected to and supported on a metal disk 146 configured to complement the annular region via an external annular region 144a, with a gap 148 between the electrode cap 144 and the metal disk 146. In the embodiment explained herein, the outer edge region 146a of the metal disk 146 is folded from the outside onto the annular region 144a of the electrode cap 144, thereby forming a closed ring 110 of the cover assembly 108. The metal disk 146 defines an internal space 102a of the housing 102, and thus defines an outer side 150a facing away from the internal space 102a and an inner side 150b facing the internal space 102a.

[0074] The metal disc 146 is also designed as a pressure relief valve (PRV) and includes an annular material weakening portion for this purpose, which in this embodiment is formed by a circular, elongated weakening groove 146b. If the pressure inside the housing 102 exceeds a predetermined limit, the metal disc 146 cracks along the groove 146b.

[0075] A distance compensation piece 152 is arranged between the metal disc 146 of the cover assembly 108 and the contact piece 142 on the winding body 134. The distance compensation piece has an annular contact area 152a, through which it is welded to the metal disc 142. The annular contact area 152a transitions radially inward into a distance compensation structure 154, which extends dome-shaped from the plane of the contact area 152a toward the metal disc 146. The distance compensation structure 154 is welded to the inner side 146b of the metal disc 146 in a connection area 154a, where the metal disc is directly attached. The connection area 154a of the distance compensation piece 152 is defined by an annular or circular groove 156 surrounding the connection area 154a.

[0076] The groove 156 in the distance compensation structure 154 is an example of a material weakening section. This groove encloses the connecting region 154a and ensures the so-called CID function (current interrupt device). If the pressure inside the housing 102 increases, the metal disc 146 arches outward. Due to the welded connection between the metal disc 146 and the distance compensation structure 154, the arched diaphragm applies tensile force to the distance compensation structure 154 of the distance compensation piece component 152. If this force is large enough, the connecting region 154a of the distance compensation piece component breaks off from the distance compensation structure 154 along the groove 156. As a result, the direct contact and electrical connection between the metal disc 146 and the distance compensation piece component 152 are interrupted, and a hole is left in the upper part of the distance compensation structure 154.

[0077] Furthermore, the distance compensation piece 152 and the metal sheet piece 142 can be replaced by components that perform the functions of these two elements. That is, for example, it is feasible to weld the contact area 152a directly to the edge strip 124 without using the metal sheet piece 142. In principle, this also applies, in particular, to the battery cells according to the invention described below.

[0078] In order to enable the metal disk 146 and the distance compensation plate component 152 to be welded together from the outside, in addition to other notches not separately indicated, the pole cap 144 also has, in particular, a through hole 144b through which the laser can reach the metal disk 146 from outside the housing 102 in the overlapping area with the connection area 154a of the distance compensation plate component 152.

[0079] Furthermore, the energy storage cell 10 includes a support ring 158 sandwiched between the metal disk 142 and the distance compensation plate component 152. The support ring 158 fits against the annular contact area 152a of the distance compensation plate component 152 and presses against the metal disk 146 from below in the outer edge region 146a of the metal disk 146. In this example, the support ring 158 is part of the seal 112, but it is not necessarily required to be.

[0080] The support ring 158 provides an additional safety function: that is, there is a risk that, when the pressure in the housing 102 increases, the entire distance compensation piece 152 itself (possibly together with the contact piece 142) may lift without breaking the connection area 154a due to the tensile force acting on the distance compensation structure 154 as explained above. In this case, the CID function fails.

[0081] However, this is avoided by the support ring 158. If the metal disc 146 arches outward, the support ring 158 keeps the distance compensation piece 152 in its position and ensures that the connection area 154a breaks, thereby guaranteeing the function of CID.

[0082] In particular, the circular opening 106 of the housing cup-shaped member 104 is closed by the cover assembly 108 using a conventional crimping process. The housing cup-shaped member 104 has a free end section 160, which is initially cylindrical, or possibly slightly tapered, before closure; this is in Figure 1 The seal 112 is shown in dashed lines. It also has a free end section, indicated by 162, which preferably extends radially inwardly alongside the end section 160 of the housing cup 104 prior to welding; this is shown in… Figure 1 The middle part is also shown with a dashed line.

[0083] In the crimping process, the free end section 160 of the housing cup-shaped member 104 is bent radially inward, wherein the seal 112 is driven by the free end section 160 and folds over the closing ring 110 of the cover assembly 108. As a result, the seal 112 is compressed in the axial direction against the cover assembly 108 by the radially inwardly bent free end section 160 of the housing cup-shaped member 104.

[0084] In order to prevent the winding body 136 or the electrode diaphragm composite 114 from being subjected to the axial force acting in the direction of the bottom 104a of the cup-shaped part at this time, the housing 102 has a tool section 104d in the axial direction between the central section 104b and the closed section 104c, in which a tool engagement structure 164 is constructed in the housing cup-shaped part 104.

[0085] The function of the tool engagement structure 164 is that it has a radially projecting portion into the interior space 102a of the housing, so that when the opening 106, specifically the housing cup-shaped part 104, is closed, the tool can be attached to the housing 102. When the opening 106 is closed, the reverse tool engages from the outside into the tool engagement structure 164, and the reverse tool axially supports the housing cup-shaped part 104 to counteract the forces acting during the crimping process and to dissipate the forces, thereby keeping the wound body 136 substantially unaffected by forces.

[0086] In order to attach the corresponding tool to the housing 102, the tool engagement structure 164 occupies an area of ​​the housing interior space 102a such that, due to the reduced cross-section, this area is no longer available for the winding body 136. The axial position of the tool engagement structure 164 determines the distance d between the main regions 120, 130 of the anode 116 or cathode 126 and the closing plane 108a of the cover assembly 108. Figure 1The distance is marked with d.

[0087] The axial extension of the cover assembly 108, as well as the distance compensation piece 152 and the contact piece 142, is coordinated with the distance d. In particular, the dome-shaped distance compensation structure 154 of the distance compensation piece 152 covers the gap 170 between the contact piece 142 and the inner side 150b of the metal disk 146, into which the tool engagement structure 164 extends.

[0088] exist Figure 1 In the energy storage cell 10 shown, the tool engagement structure 164 is formed by a radially upward-facing, inwardly circumferentially surrounding groove 166, which provides a tool engagement groove 168. However, other structures are also conceivable.

[0089] When constructing the energy storage cell 10, the tool engagement structure 164 is created only after the winding body 136 has been arranged in the internal space 102a of the housing 102, specifically the tool engagement groove 168. Otherwise, the winding body 136 would abut against the tool engagement groove 168, and due to its smaller cross-section, it might block the path into the internal space 102a. Subsequently, the cover assembly 108, together with the seal 112, is fitted onto the tool engagement groove 168 and a crimping process is performed.

[0090] It should also be noted that the groove shown has a slight undercut. This could be the result of height calibration, for example, during or after crimping. Preferably, the groove 166 for engaging the tool is initially constructed without visible undercuts. The undercut is formed only during calibration.

[0091] 2. The energy storage cell according to the present invention Figures 3 to 7 An energy storage cell 100 according to the present invention is shown, wherein functionally corresponding components and members have the same characteristics as those in the present invention. Figure 1 The same reference numerals are used in the energy storage cell 10; now, only the longitudinal axis has reference numeral 100a. Unless otherwise stated, for Figure 1 and Figure 2 The contents described for the energy storage cell 10 are applicable accordingly to these components and parts.

[0092] In the energy storage cell 100 according to the invention, the overhang 141a formed by the side strip 124 of the anode current collector 118 is compressed in the axial direction relative to the winding body 136 between the main region 120 of the anode current collector 118 and the contact piece member 142. In particular, the side strip 124 is compressed and / or bent for this purpose. Figure 3This situation is illustrated here with a partial magnification. The axially compressed overhang 141a of the anode current collector 118 is separately indicated by 172. Thus, the energy storage cell 100 according to the invention includes an electrode-diaphragm composite 114 having an axially compressed overhang 172. In the case of the arrangement of the winding 136 shown in the figure, the compressed overhang 172 is the overhang 141a of the anode current collector 118 formed by the edge strip 124; in the case of the reverse arrangement of the winding 136 explained above, which is not shown separately here, the compressed overhang 172 is the overhang 141b of the cathode current collector 128 formed by the edge strip 134. The winding 136 is shown in a partial view looking toward the anode main region 120 and the cathode main region 130, but for clarity, the diaphragms 138 and 140 are not shown therein.

[0093] For example, the bending can be performed in the manner described in the aforementioned European patent application 23202968.6, in which the outer free loop of the slat 124 of the anode current collector 118 is bent radially inward, and further pressed to a certain extent against the loop of the radially inner slat 124 when the contact piece 142 is fitted before welding. For example, the slat can be bent at an angle ranging from 30° to 90°. The slat can also be cut for this purpose, but this is not necessarily required.

[0094] For example, compression can be achieved by pressing the contact piece against the edge strip, causing the edge strip to deform. In many cases, this does not result in directional bending, but rather in non-directional compression. Therefore, some sections of the edge strip can be bent radially outward and others radially inward.

[0095] Both bending and compression create a mating surface, which is formed by the overhang that is compacted or reinforced due to bending and / or compression.

[0096] In summary, compared with the above... Figure 2 Compared to the cases of the unloaded winding configurations of the extended portions 141a and 141b, the extended portion 172 compressed in the axial direction has higher stability and stronger load capacity against forces acting on the compressed extended portion 172 in the axial direction.

[0097] At this time, the compressed overhang 172 has a smaller axial extension than the overhangs 141a and 141b in the winding configuration. Here, the axial extension of the compressed overhang 172 in the axial direction is particularly between 10% and 80%, preferably between 15% and 60%, more preferably between 15% and 50%, and even more preferably between 25% and 45% of the axial extension of the overhangs 141a and 141b in the unloaded winding configuration. If necessary, the compressed overhang 172 can also be compressed to such an axial extension that it is less than 10% of the axial extension of the overhangs 141a and 141b in the unloaded winding configuration.

[0098] In the energy storage cell 100 according to the invention shown here, the housing cup-shaped member 104 is designed without a tool engagement structure 164. That is, there is no tool engagement structure 164, whether in the form of a tool engagement groove 166 or in the form of other structures having a corresponding function for attaching a tool to the housing cup-shaped member when the opening 106 of the housing cup-shaped member 104 is closed (as explained above).

[0099] By means of the side strip 172 of the compressed or bent anode current collector 118, the electrode diaphragm composite 114, that is, the winding 136 itself (but also with the welded metal sheet component 142), has sufficient stability to act as a reverse element to overcome the axial force acting during welding, so that the end section 160 of the housing cup-shaped part can be bent without damaging the winding 136.

[0100] Here, a different closing method is used than in the case of a housing with a tool engagement structure. For example, radial bending can be performed by rotating rollers that travel circumferentially over the free end region 160 of the housing cup-shaped member 104 and press radially inward and axially against the bottom 104a of the cup-shaped member. In this case, the steps that might be necessary in the energy storage cell 100 with a housing 102 having a tool engagement structure 164, such as the height calibration mentioned above, can be omitted.

[0101] By omitting the tool engagement structure, the housing cup-shaped member 104 can be designed as a cylinder from the bottom 104a to the closed section 104c. Therefore, compared to the otherwise identical housing 102 with the tool engagement structure 164, the gap 170 between the contact piece 142 and the inner side 150b of the metal disc 146 can be kept shorter in the axial direction, allowing the winding body 136 to be designed to be longer in the axial direction. The longer winding body 136 in the axial direction allows the energy storage cell 100 to have greater capacity and power while keeping other external dimensions constant.

[0102] exist Figure 3 In the diagram, the axial distance between the main regions 120 and 130 of the anode 116 and cathode 126 and the closing plane 108a of the cover assembly is marked as d1. For comparison, Figure 3 It was also shown again in accordance with Figure 1 The corresponding distance d in the energy storage cell 100 with tool engagement structure 164.

[0103] It can be seen that the distance d1 is Δd smaller than the distance d, and the main regions 120 and 130 of the anode 116 and cathode 126 of the winding body 136 used according to the present invention have a greater than that according to the present invention. Figure 1 The winding body 136 extends axially by a large Δd. The cover assembly 108 and the distance compensation piece 152 are adapted to accommodate the now shortened gap 170 in the axial direction. In particular, the dome-shaped distance compensation structure 154 of the distance compensation piece 152 is designed to be significantly flatter, which is achieved through... Figure 1 To illustrate, a comparison is needed. In this embodiment, the metal disk 142 has also been adjusted, with the metal disk arching towards the distance compensation piece 152 in the region defined radially outward by the groove 146b. Now, this arching is smaller, which is consistent with... Figure 1 This is also reflected in the comparison.

[0104] Preferably, the length or height of the housing 102 of the energy storage cell 100 is between 50 mm and 150 mm. Preferably, its diameter is in the range of 15 mm to 60 mm. In a particularly preferred embodiment, the energy storage cell 100 has a specification of 21700.

[0105] With other aspects of the housing 102 remaining unchanged, a value of d1, for example, between 0.6 mm and 3.0 mm, particularly between 0.8 mm and 2.5 mm, preferably between 1.0 mm and 2.0 mm, and preferably between 1.2 mm and 1.6 mm, can be achieved by combining the wound body 136 used according to the invention with the compressed overhang 172 and the housing 102 according to the invention without tool engagement structure. A value of Δd, for example, between 1.2 mm and 2.5 mm, particularly between 1.8 mm and 2.2 mm, can also be achieved. The main regions 120, 130 of the anode 116 and cathode 126 can be designed to increase the value of Δd in the axial direction. With this value of Δd, a capacity increase of 1% to 3% is obtained in the case of a common housing size with a wound body diameter between 15 mm and 60 mm.

[0106] Of course, the values ​​of d1 and Δd, and the resulting capacity increase, depend on the basic dimensions of the energy storage element's structural form.

[0107] exist Figure 3In the embodiment shown, the support ring 158 is again part of the seal 112. Here, the seal has a C-shaped cross-section, wherein the support ring 158 is formed by the side of the seal 112 abutting against the inner side 110a of the closing ring 110 of the cover assembly 108. Figure 3 The configuration is shown.

[0108] Figure 4 A modification is shown in which the distance compensation structure 154 is provided via a contact piece 142. In this case, the contact piece 142 is designed to structurally correspond to the distance compensation piece 152, and the annular contact area 142a of the contact piece 142 transitions radially inward into the distance compensation structure 154.

[0109] In this case, the support ring 158 is directly attached to the contact piece component 142. Figure 4 A modified scheme is shown where the distance d1 remains constant, wherein the distance compensation structure 154 has a corresponding axial extension. The seal 112 and support ring 158 are adapted accordingly. However, the distance d1 can also be reduced again accordingly, i.e., to match the... Figure 3 , Figure 5 and Figure 6 The distance compensation structure 154 is designed in the same way as the distance compensation piece component 152 shown, but with a flatter design.

[0110] Figure 5 A second embodiment of the energy storage cell according to the invention is shown, in which the seal 112 and the support ring 158 are designed as separate components. In this case, a distance is left between the seal 112 and the contact piece 142.

[0111] In the modified version where the distance compensation structure 154 is provided by the contact piece component 142, the support ring 158 is directly supported on the contact piece component 142 in this case.

[0112] Figure 6 A third embodiment of the energy storage cell 100 according to the invention is shown, in which the seal 112 and the support ring 158 are also designed as separate components. Unlike the second embodiment, the seal 112 is supported on the contact piece member 142 and includes a support section 112a for this purpose. The support section 112a of the seal 112 extends radially alongside the distance compensation piece member 152, which extends axially between the inner side 110a of the annular section 110 of the cover assembly 108 and the contact piece member 142.

[0113] In this case, the separate support ring 158 can be omitted, and the support section 112a of the seal 112 forms the support ring 158 when the distance compensation structure 154 is provided by the contact piece component 142. If necessary, the support ring 158 is formed by the support section 112a of the seal 112 such that the support section is supported more radially inward on the contact piece component 142.

[0114] Figure 7 A fourth embodiment of the energy storage cell 100 according to the present invention is shown, wherein the seal 112 includes not only the support section 112a but also the support ring 158.

[0115] By eliminating the tooling connection structure, it is further achieved that the winding body 136 is welded to the cover assembly 108 before the winding body 136 is inserted into the housing 102, because there is no channel that would block the winding body 136 from entering the housing 102 (as described above). Figure 1 The structure described above.

[0116] This paves the way for the manufacturing method described at the beginning, in which the first step is to manufacture only... Figure 3 The entire cap-wound composite, marked with 174, is then inserted into the housing cup-shaped part 104.

Claims

1. An energy storage element having a) A housing (102) defining the longitudinal axis (100a) and internal space (102a) of the energy storage element (100) and comprising a metal housing cup (104) and a cover assembly that closes the housing cup (104). b) A sealing assembly with a seal (112) that radially surrounds the cover assembly (108) and seals relative to the housing cup-shaped member (104), wherein, The seal (112) is compressed against the cover assembly (108) by the radially inwardly bent free end section (160) of the housing cup (104). c) An electrode-diaphragm composite (114) having a sequence of anode (116) / diaphragm (138) / cathode (126) / diaphragm (140), the electrode-diaphragm composite being disposed in the housing cup-shaped member (104) and in the form of a cylindrical winding (136), wherein c1) The anode (116) includes an anode current collector (118) having a strip-shaped main region (120) and free side strips (124), the strip-shaped main region being attached with a layer of negative electrode material (122), the free side strips not being attached with the electrode material (122) and including a first longitudinal edge (118a) of the anode current collector (118), wherein the free side strips (124) are separated from a first end side (114a) of the electrode diaphragm composite (114) and form an overhang (141a) on the first end side (114a). c2) The cathode (126) includes a cathode current collector (128) having a strip-shaped main region (130) and free side strips (134), the strip-shaped main region being attached with a layer of positive electrode material (132), the free side strips not being attached with the electrode material (132) and including a first longitudinal edge (128a) of the cathode current collector (128), wherein the free side strips (134) are separated from the second end side (114b) of the electrode diaphragm composite (114) and form an overhang (141b) on the second end side (114b). d) Contact piece component (142), said contact piece component d1) Supported on the overhang (141a) of the anode current collector (118) and covering the first end side (114a) of the electrode diaphragm composite (114) and connected to the overhang (141a); or d2) Located on the overhang (141b) of the cathode current collector (128) and covering the second end side (114b) of the electrode diaphragm composite (114) and connected to the overhang (141b); Its features are, e) The extensions (141a, 141b) connected to the contact piece component (142) are extensions (172) that are compressed in the axial direction; and f) The housing cup-shaped part (104) is designed to be tool-free joint structure (164).

2. The energy storage element according to claim 1, characterized in that, The cover assembly (108) defines a closed plane (108a), and the axial distance (d1) between the main regions (120, 130) of the anode (116) and the cathode (118) and the closed plane (108a) is between 0.6 mm and 3.0 mm, particularly between 0.8 mm and 2.5 mm, preferably between 1.0 mm and 2.0 mm, and preferably between 1.2 mm and 1.6 mm.

3. The energy storage element according to claim 2, characterized in that, The cover assembly (108) includes a surrounding outer closure ring (110) surrounded by the seal (112), wherein the closure plane (108a) is defined by the inner side (110a) of the inner space (102a) of the closure ring (110) facing the housing (102).

4. The energy storage element according to claim 3, characterized in that, The cover assembly (108) includes a metal disk (146) welded to the distance compensation structure (154) in a connection region (154a), the distance compensation structure... a) Provided by a distance compensation piece (152) connected to the contact piece (142); or b) Provided via the contact piece component (142).

5. The energy storage element according to claim 4, characterized in that, The distance compensation structure (154) is provided by the distance compensation piece (152), and a) A support ring (158) is provided between the distance compensation piece (142) and the metal disc (146), the support ring being a separate component or being included within the seal (112); b) There is an axial distance between the contact piece (142) and the seal (112), or the seal (112) includes a support section (112a) which supports the seal on the contact piece (142).

6. The energy storage element according to claim 4, characterized in that, The distance compensation structure (154) is provided by the contact piece (142), and a support ring (158) is provided between the contact piece (142) and the metal disk (146), the support ring being a separate component or being included within the seal (112).

7. The energy storage element according to claim 5 or 6, characterized in that, The distance compensation structure (154) provides CID functionality, and for the purpose thereof, the distance compensation structure (154) includes a material weakening portion, in particular a groove (156), that encloses the connection region (154a) of the distance compensation structure (154).

8. The energy storage element according to any one of claims 5 to 7, characterized in that, The metal disk (146) is designed as a PRV and includes, for the purpose of the present invention, a material weakening portion, particularly an annular or circular weakening groove (156).

9. A method for manufacturing an energy storage element (100) according to any one of claims 1 to 8, comprising the following steps: (A) A housing (102) is provided with a metal housing cup-shaped part (104) and a lid assembly (108). (B) Provide a sealing assembly with a seal (112) and a support ring (158). (C) Provide an electrode diaphragm composite (114); (D) Connecting, in particular welding, the contact piece (142) to the strip (124) of the anode current collector (118) or to the strip (134) of the cathode current collector (128); (E) Position the seal (112) and the support ring (158); (F) Connect the cover assembly to the contact piece (142); (G) Close the cup-shaped part of the housing (104); Its characteristics include the following steps: (H) Compress the edge strips (124, 130) in the axial direction or bend the edge strips (124, 130), preferably before or at the same time as performing step (D); (I) Steps (D), (E), (F) and (H) are performed outside the shell cup-shaped part (104) to form a cap winding composite (174). (K) Before performing step (G), the cap winding composite (174) and the seal (112) are inserted into the housing cup (104).

10. The method according to claim 9, characterized in that, (L) The distance compensation structure (154) is provided by the distance compensation piece (152), and in step (F) the cover assembly (108) is connected to the distance compensation structure (154) and the distance compensation piece (152) is connected to the contact piece; or (M) The distance compensation structure (154) is provided through the contact piece component (142), and in step (F) the cover assembly (108) is connected to the distance compensation structure (154).

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