Cap assembly, energy storage cell, battery module and method for producing cap assembly

Abstract

The invention relates to a cover assembly for a cell housing of an energy storage cell wherein the cover assembly is arranged in an installed state to be able to fill the cell housing with an electrolyte wherein the cover assembly comprises: (i) an end plate having a fixing assembly comprising an opening, (ii) wherein the end plate further comprises a circumferential groove; (iii) a first closing element, which is arranged to close the opening before filling the cell housing and is penetrated by a filling element, by means of which an electrolyte can be filled into the cell housing, in order to fill the cell housing; (iv) a second closure element arranged to close the opening after filling the cell housing; (v) wherein the circumferential recess is arranged such that, when a specific overvoltage is reached or exceeded in the cell housing, the end plate can be split in the region of the recess such that the electrolyte can be discharged at least partially through the split region.

Description

Technical Field

[0001] The invention relates to a cover assembly, an energy storage battery cell, a battery module and a method for manufacturing the cover assembly. Background Art

[0002] In the field of energy storage cells, in particular battery cells, in particular lithium-ion battery cells, mainly cylindrical, prismatic and pouch-shaped battery cells are known. Battery cells for storing electrical energy play a central role in the field of so-called electric vehicles, both in vehicles with purely electric drives and in vehicles with hybrid drives. For example, a battery module for a 12V starter battery can have four battery cells, while a high-voltage energy store can have a plurality of battery modules.

[0003] In the case of battery cells, the energy storage device and the electrodes connected thereto can be arranged in the cell housing. The electrical connection to the electrodes provided can be used to tap off electrical power from outside the cell housing. The energy storage device can contain compounds that can lead to gaseous emissions in the cell housing. If the temperature is high at the same time, high voltages can occur in the cell housing, thereby increasing the risk of thermal runaway of the battery cell. Summary of the invention

[0004] An object of the present disclosure is to provide a cap assembly, an energy storage cell, a battery module, a motor vehicle, and a method for manufacturing a cap assembly, which are improved with respect to the above-mentioned problems.

[0005] This object is achieved by a cover component according to claim 1 , an energy storage cell, a battery module, a motor vehicle and a method for producing a cover component.

[0006] A first aspect of the solution relates to a cover assembly for a cell housing of an energy storage cell, wherein the cover assembly is configured in an installed state to be able to fill the cell housing with an electrolyte, wherein the cover assembly comprises: (i) an end plate having a fixing assembly, the fixing assembly comprising an opening, (ii) wherein the end plate also comprises a circumferential groove; (iii) a first closing element, which is configured to close the opening before filling the cell housing and is penetrated by a filling element for filling the cell housing, through which the electrolyte can be filled into the cell housing; (iv) a second closing element, which is configured to close the opening after filling the cell housing; (v) wherein the circumferential groove is configured to enable the end plate to rupture in the area of ​​the groove when a specific overpressure is reached or exceeded in the cell housing, so that the electrolyte can be at least partially discharged through the ruptured area.

[0007] The terms "comprises," "comprising," "containing," "having," "having," "with," or any other variations thereof as may be used herein shall cover a non-exclusive inclusion. Thus, for example, a method or apparatus that comprises or has a list of elements is not necessarily limited to those elements but may contain other elements not expressly listed or inherent to such method or apparatus.

[0008] In addition, unless expressly stated to the contrary, "or" refers to an inclusive or rather than an exclusive "or". For example, condition A or B is satisfied by one of the following conditions: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and both A and B are true (or exist).

[0009] The terms "a" or "an" as used herein are defined as meaning "one / one or more". The terms "another" and "another" and any other variations thereof should be construed as meaning "at least one other".

[0010] As used herein, the term "plurality" should be understood to mean "two or more."

[0011] As used herein, the term "configured" or "set" to fulfill a specific function (and its corresponding modification) is to be understood as meaning that the corresponding device is already in a design or setting in which it can perform the function, or that it is at least settable - i.e. configurable - so that it can perform the function after the corresponding setting. The configuration can be performed here, for example, by setting parameters of a process flow or a switch etc. accordingly to activate or deactivate a function or setting. In particular, the device can have a plurality of predetermined configurations or operating modes, so that the configuration can be performed by selecting one of these configurations or operating modes.

[0012] The term "electrode coil" as used herein is to be understood in particular as a device which, as a component of a primary cell, in particular a battery cell, also serves to store chemical energy and to output electrical energy. For this purpose, the electrode coil has at least two electrodes, an anode and a cathode, and a separator, in particular an electrically insulating separator, which can at least partially receive an electrolyte. Here, the anode, separator and cathode are wound around an axis to form an electrode coil. Before the electrical energy is output, the stored chemical energy is converted into electrical energy. During the charging of the battery cell, the electrical energy supplied to the electrode coil is converted into chemical energy and stored. Particularly preferably, some electrodes are connected to one another, in particular electrically connected.

[0013] The term "separator layer" or "separator" as used herein is to be understood as referring in particular to an electrical insulating device that separates and spaced the anode from the cathode. The separator layer is preferably applied to the anode layer and / or the cathode layer. The separator layer is preferably constructed as a separate body. The separator layer or separator can also at least partially receive an electrolyte, wherein the electrolyte preferably contains lithium ions. The electrolyte can also be electrochemically connected to adjacent layers of the electrode stack. Preferably, the shape of the separator corresponds essentially to the shape of the anode of the electrode stack. The separator is preferably constructed as a thin-walled, particularly preferably as a microporous foil. Preferably, the separator layer or separator is wetted with an additive, which also improves the mobility of the separator layer or separator. Wetting is particularly preferably carried out with an ionic additive. Preferably, the separator layer or separator extends at least partially to the boundary edge of at least one electrode. Particularly preferably, the separator layer or separator extends beyond all boundary edges of adjacent electrodes.

[0014] The term "electrolyte" as used herein is to be understood in particular as a liquid or solid material through which ions can be conducted, thereby enabling current transport between the electrodes of the battery, in particular between the cathode and the anode. Unlike the electronic conductivity (due to electrons) in the electrode material, the electrolyte must be ionically conductive, i.e. conduct the current by transporting charged atoms or molecules (ions). Advantageously, the electrolyte is chemically stable to decomposition in a wide temperature window and electrochemically stable to decomposition in the maximum possible voltage window. Ideally, it is non-toxic and non-flammable and has at least a high flash point and a low heat of combustion. Liquid systems may be more preferred than polymers and solid electrolytes due to better electrical conductivity.

[0015] According to the energy storage cell of the first aspect, it can be achieved that when the cover assembly is installed on the cell housing of the energy storage cell, when a specific pressure is reached or exceeded in the cell housing, the end plate can be split in the area of ​​the surrounding groove. This can prevent the pressure currently existing in the cell housing from increasing further. It is preferably achieved that a controlled, directional and therefore safe pressure relief is achieved. The cover assembly can thus not only achieve reliable and safe electrolyte filling under normal conditions, but also be used to reduce the overpressure that may occur in the cell due to strong heating caused by internal short circuits in the cell. In addition, the cover assembly can be manufactured separately from the cell housing. This can be advantageous when assembling the cover assembly on the cell housing, because the opening, the first closing element, the fixing assembly and the groove can be arranged or formed before the cover assembly is fixed on the cell housing. The opening is closed only by the second connecting element after filling the electrolyte. When the cover assembly is already fixed on the cell housing, the opening formed by, for example, a drilling process can cause contaminants, especially metal debris, to enter the cell housing, thereby impairing the function of the energy storage cell. This can be avoided by manufacturing the cover assembly separately.

[0016] Preferred embodiments of the cover assembly are described below, which can each be combined in any way with one another and with the further described aspects, unless this is expressly excluded or is technically impossible.

[0017] In some embodiments, the first closure element comprises a film and / or foil placed in the opening. Film or foil in this case is preferably understood to mean any thin, flat structure made of, for example, plastic, rubber, metal or other material or a combination of two or more different materials, which has a large surface area relative to its thickness. Thus, on the one hand, a good seal of the opening can be achieved, and on the other hand, a good permeability of the first closure element can be achieved. The film or foil is preferably made of an elastic material. Thus, it can be achieved that there is no or only a relatively small amount of electrolyte or solvent present at the position where the filler element penetrates the film or foil.

[0018] In some embodiments, the first closing element is configured to be pierced and / or penetrated by a filling element designed as a hollow needle for filling the cell housing, thereby making it possible to fill the closed cell housing.

[0019] In some embodiments, the second closing element is arranged to be connected to the fixing component in a force-locking manner, in particular by screwing, in order to close the opening, in particular to close the opening in a sealing manner. For example, the opening can be provided with an internal thread in this case and the second closing element can be provided with an external thread, so that the second closing element can be screwed into the opening. This makes it particularly easy to achieve a reliable sealing of the opening after filling the energy storage cell.

[0020] In some embodiments, the second closing element is arranged to be connected to the fixing component in a material-locked manner, in particular by welding and / or soldering, in order to close the opening, in particular to close the opening in a sealed manner. For this purpose, for example, a flange can be provided on the second closing element, which is welded or soldered to the fixing component of the filling connector. In this way, a reliable sealing of the opening after filling the battery cell can also be easily achieved.

[0021] In some embodiments, the first closing element is releasably arranged in the opening, so that the first closing element can be at least partially removed from the opening, in particular pressed out, by overpressure. For example, a surrounding groove can be provided in the opening, in which the first closing element is retained. If the overpressure in the battery cell exceeds a certain value, the first closing element is released from the surrounding groove of the opening, whereby the overpressure in the battery cell housing can be reduced.

[0022] In some embodiments, the second closing element has a rupture membrane or a rupture disk, which is arranged to at least partially open or release the opening when a specific overpressure is reached or exceeded in the battery cell housing, so that the electrolyte can be at least partially discharged through the opening. The rupture membrane or the rupture disk is made of a suitable material, such as aluminum, an aluminum alloy, steel or PTFE, and is therefore configured so that it can rupture and / or release the opening when a specific overpressure is reached or exceeded in the battery cell. A controlled, directional and therefore safe pressure relief is thus preferably achieved. As a result, the cover assembly can reduce the overpressure that may occur in the battery cell, for example due to strong heating caused by an internal short circuit in the battery cell.

[0023] A second aspect of the solution relates to an energy storage cell, comprising: (i) a cell housing; (ii) two electrodes arranged in the cell housing; and (iii) a cover assembly according to the first aspect, wherein the cover assembly is fixed to the cell housing so that the cell housing is closed, in particular airtight.

[0024] A third aspect of the solution relates to a battery module having a plurality of energy storage cells according to the second aspect.

[0025] A fourth aspect of the solution relates to a motor vehicle having an electric drive or a hybrid drive and a battery module according to the third aspect.

[0026] A fifth aspect of the solution relates to a method for manufacturing a cover assembly according to the first aspect, comprising the following steps: (i) providing an end plate having a circular base surface and a longitudinal axis (L) extending perpendicular to the circular base surface; (ii) forming a substantially centrally arranged through-opening along the longitudinal axis on the circular end plate; (iii) forming a groove circumferentially arranged relative to the longitudinal axis on the surface of the circular end plate; (iv) arranging a fixing component in the edge area of ​​the opening; (v) arranging a first closing element to close the opening, wherein the first closing element is configured to close the opening in the installed state before the cell housing is filled with electrolyte and the filling element is penetrated, in particular pierced or penetrated in order to fill the cell housing, so that the electrolyte can be filled into the cell housing through the filling element; (vi) arranging a second closing element in the installed state and after the cell housing is filled, wherein the second closing element is configured to close the opening after the cell housing is filled.

[0027] The features and advantages explained with respect to the first aspect of the solution also apply correspondingly to the further described aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Further advantages, features and possible applications result from the following description of preferred embodiments in conjunction with the attached drawings.

[0029] Here

[0030] Figure 1 schematically illustrates a battery cell according to one embodiment;

[0031] Figure 2 schematically illustrates a cover assembly according to one embodiment;

[0032] FIG. 3A to FIG. 3D schematically illustrates a cover assembly according to one embodiment in a manufactured state; and

[0033] Figure 4 A flow chart is shown which illustrates a preferred specific embodiment of a method for producing a battery cell. DETAILED DESCRIPTION

[0034] In the drawings, the same reference numerals are used throughout for elements that are identical or correspond to one another.

[0035] exist Figure 1 Schematically shows a battery cell 100 according to one embodiment. The battery cell 100 has a hollow cylindrical cell housing 110, which has a longitudinal axis L. The cell housing 110 can also be designed as a cuboid. The cell housing 110 includes an electrically conductive material. However, it is also conceivable that the cell housing 110 includes an electrically insulating material. The cell housing 110 is closed on one side by a base plate 130. On the side opposite to the base plate 130, the cell housing 110 is closed by a cover assembly 140. The cover assembly 140 has an end plate 120 and is Figure 2 The end plate 120 is arranged in a circumferential groove of the cell housing 110, wherein an electrical insulation element 150 is arranged between the end plate 120 and the groove, which electrically insulates the end plate 120 from the cell housing 110. In addition, the electrical insulation element 150 acts in a gas-tight manner, so that the cell housing 110 can be closed in a gas-tight manner by the cover assembly 140. The opening of the groove here points to the longitudinal axis L.

[0036] However, it is also conceivable that no electrically insulating element 150 is arranged between the end plate 120 and the recess. This may be expedient when the cell housing 110 comprises an electrically insulating material. It is also conceivable that an electrode of one polarity is led through the base plate 130 of the cell housing 110, wherein the lead-through is electrically insulated relative to the cell housing 110 and is also installed in the base plate 130. In this case, the cover can also be directly connected to the cell housing 110, in particular welded.

[0037] The electrode coil 160 is arranged in the battery cell housing 110. The electrode coil 160 includes an electrode 170 having a first positive polarity and an electrode 175 having a second negative polarity. However, the electrode coil 160 can also be configured so that the first polarity is negative and the second polarity is positive. The electrode coil 160 is arranged in the battery cell housing 110 so that the electrodes 170 of positive polarity and the electrodes 175 of negative polarity are arranged alternately in the radial direction. A separator 180 is arranged between the electrodes 170 of positive polarity and the electrodes 175 of negative polarity, respectively, so that the electrodes 170, 175 of different polarities are electrically insulated from each other, wherein the separator 180 has an electrically insulating material. In addition, an electrolyte 190 is schematically shown in the battery cell housing 110. The electrolyte 190 is filled into the battery cell housing 110 through the cap assembly 140.

[0038] exist Figure 2 Schematically shown in FIG. 1 is a cover assembly 140 according to one embodiment. The cover assembly 140 has an end plate 120. The end plate 120 has a groove 210 that is circumferential relative to the longitudinal axis L. The groove 210 has a triangular cross-section. Likewise, the cross-section may have a semicircular, rectangular or other shape. The thickness of the end plate 120 in the region of the groove 210 is smaller than the thickness of the end plate 120 when it is manufactured, and therefore the end plate can be more easily cracked in these regions.

[0039] The end plate 120 has a fixing assembly 200, which has an opening 220 arranged substantially centrally relative to the end plate 120. The fixing assembly 200 is arranged symmetrically relative to the longitudinal axis L. The fixing assembly 200 includes a first support ring 203 arranged on one side of the end plate 120 and a second support ring 207 arranged on the other side of the end plate 120. The opening 220 is closed by a membrane 230. Likewise, instead of the membrane 230, a foil can close the opening 220. The electrolyte 190 can be filled into the cell housing 110 through the membrane 220 by means of a filling tool, in particular a hollow needle (not shown here), which is suitable for being pushed through the membrane 230. After filling and after the filling tool is pulled out of the cell housing 110 and the membrane 230, the membrane 230 is closed. The closure should prevent that a large amount of electrolyte 190 can escape from the cell housing 110. In particular, in the case of an electrolyte 190 whose boiling point is below room temperature, boiling can occur. However, the closing membrane 230 is only sufficient for the filling process. A stable and permanent closure is required during operation of the battery cell 100 . Therefore, a cover 240 is additionally provided, which can comprise metal and is fastened to the fastening component 200 in a gas-tight manner.

[0040] In the event of an overpressure in the closed cell housing 110 , it is provided that the end plate 120 breaks apart in the region of the recess 210 . As a result, the gas or electrolyte 190 can escape from the cell housing 110 and a further increase in pressure can be avoided.

[0041] exist FIG. 3A to FIG. 3D Schematically illustrates a manufacturing state of a cover assembly according to one embodiment.

[0042] Figure 3A The end plate 120 is shown in a side view with a longitudinal axis L. In the side view of the end plate 120 , the longitudinal axis L extends essentially perpendicularly to the end plate 120 .

[0043] exist Figure 3B In the embodiment, the end plate 120 has an opening 220 arranged essentially in the center. A first support ring 203 is fixed to one side of the opening 220. The fixing is preferably configured as a material connection. The first support ring 203 is arranged axially symmetrically with respect to the longitudinal axis L. The end plate 120 also has a circumferential groove 210, which is arranged radially further outwards with respect to the longitudinal axis L than the first support ring 203. The opening 220 is closed by a membrane 230, which rests on the first support ring 203 in the opening 220.

[0044] Figure 3C Shown according to Figure 3B The arrangement of the second support ring 207, wherein the second support ring 207 is additionally fixed on the other side of the opening 220. This fixation is also preferably configured as a material connection. Thus, the membrane 230 is arranged between the first support ring 203 and the second support ring 207.

[0045] Figure 3D The arrangement shown in corresponds to Figure 2 The layout of Figure 3C In contrast, the cover 240 is fastened to the upper region of the fastening arrangement 200 relative to the plane of the drawing.

[0046] It is also conceivable that, instead of the first support ring 203 and the second support ring 207, the fixing component 200 is formed in one piece and forms a surrounding groove. In this case, the groove is open in a section so that the membrane 230 can be arranged in the groove. In this case, the membrane 230 is preferably deformable. The opening can then be closed by mechanical forming. The one-piece fixing component 200 can be fixed to the inner side of the opening 220 in a corresponding material-locking manner (not shown here).

[0047] Figure 4 A flow chart 400 is shown illustrating one embodiment of a method for manufacturing one embodiment of the lid assembly 140 .

[0048] In a first step 410 of the method, an end plate 120 is provided which has a circular base area and a longitudinal axis L extending perpendicularly to the circular base area.

[0049] In a further step 420 of the method, a substantially centrally arranged through-going opening 220 is formed on the circular end plate 120 along the longitudinal axis L. The opening 220 can be formed in particular by a drilling step.

[0050] In a further step 430 of the method, a circumferential groove 210 is formed on the surface of the circular end plate 120 , which groove is circumferential relative to the longitudinal axis L. The circumferential groove 210 can be formed, in particular, by milling or laser engraving.

[0051] In a further step 440 of the method, the fastening arrangement 200 is arranged in the edge region of the opening 220. In particular, the fastening arrangement 200 can have a first support ring 203 and a second support ring 207, wherein during the arrangement one of the support rings 203, 207 is fixed to the end plate 120 and the other support ring 203, 207 is provided.

[0052] In a further step 450 of the method, the film 230 is arranged to close the opening 220, wherein the film 230 is arranged to close the opening 220 in the installed state before the cell housing 110 is filled with the electrolyte 190 and to be penetrated, in particular pierced or penetrated, by a filling element for filling the cell housing 110, through which the electrolyte 190 can be filled into the cell housing 110. When closing the opening, the film 230 rests on the support elements 203, 207 fixed to the end plate 120.

[0053] In a further step 460, the provided further support ring 203, 207 is placed under contact pressure on the opening 220. This further support ring 203, 207 is then connected to the end plate 120 in a materially locked manner, so that the membrane 230 is arranged between the two support rings 203, 207. It is also conceivable that one or both support rings 203, 207 are connected to the end plate 120 in a non-positively locked manner. The materially locked connection can be achieved by a welding process, the non-positively locked connection can be achieved by a screw connection.

[0054] In a further step 470 of the method, in the installed state and after filling of the cell housing 110 , a cover 240 is arranged which is provided to close the opening 220 after filling of the cell housing 110 .

[0055] Although at least one exemplary embodiment has been described above, it should be noted that there are a large number of variations. It should also be noted that the exemplary embodiments described represent only non-limiting examples and are not intended to limit the scope, applicability, or configuration of the apparatus and methods described herein. On the contrary, the foregoing description will provide guidance for those skilled in the art for implementing at least one exemplary embodiment, wherein it should be understood that various changes may be made to the functions and arrangements of the elements described in the exemplary embodiments without departing from the subject matter and their legal equivalents respectively specified in the appended claims.

[0056] Reference numerals list

[0057] 100 battery cells

[0058] 110 battery cell shell

[0059] 120 end plate

[0060] 130 base plate

[0061] 140 cover assembly

[0062] 150 Insulation Elements

[0063] 160 electrode coil

[0064] 170 Positive polarity electrode

[0065] 175 Negative electrode

[0066] 180 partition

[0067] 190 electrolytes

[0068] 200 fixed components

[0069] 203 first support ring

[0070] 207 second support ring

[0071] 210 grooves

[0072] 220 opening

[0073] 230 Film

[0074] 240 caps

[0075] 400 is a flow chart illustrating one embodiment of a method for manufacturing a lid assembly.

[0076] 410 Provide end plate

[0077] 420 forms a substantially centrally arranged through opening

[0078] 430 forms a surrounding groove

[0079] 440 Arrangement of fixed components

[0080] 450 layout film

[0081] 460 connection fixing components

[0082] 470 layout cover

Claims

1. A cover assembly (140) for a cell housing (110) of an energy storage cell (100), wherein: The cap assembly (140) is configured to fill the cell housing (110) with an electrolyte (190) in an installed state, wherein the cap assembly (140) comprises: an end plate (120) having a fixing assembly (200) including an opening (220); Wherein, the end plate (120) further comprises a surrounding groove (210); a first closing element (230) which is arranged to close the opening (220) before the cell housing (110) is filled and is penetrated by a filling element for filling the cell housing (110), through which the electrolyte (190) can be filled into the cell housing (110); a second closing element (240) configured to close the opening (220) after the cell housing (110) is filled; The circumferential groove (210) is configured to enable the end plate (120) to rupture in the region of the groove (210) when a specific overpressure is reached or exceeded in the battery cell housing (110), so that the electrolyte (190) can be at least partially discharged through the ruptured region.

2. The cover assembly (140) according to claim 1, wherein: The first closing element (230) comprises a membrane and / or a foil arranged in the opening (220).

3. The cover assembly (140) according to claim 1 or 2, wherein: The first closing element (230) is configured to be pierced and / or penetrated by a filling element configured as a hollow needle in order to fill the cell housing (110).

4. The cover assembly (140) according to any one of the preceding claims, wherein: The second closing element (240) is configured to be connected to the fixing assembly (200) in a force-locking manner in order to close the opening (220).

5. The cover assembly (140) according to any one of the preceding claims, wherein: The second closing element (240) is configured to be connected to the fixing component (200) in a materially bonded manner in order to close the opening (220).

6. The cover assembly (140) according to any one of the preceding claims, wherein: The first closure element (230) is releasably arranged in the opening (220), such that the first closure element (230) can be at least partially removed from the opening (220) by the overpressure.

7. The cover assembly (140) according to any one of the preceding claims, wherein: The second closure element (240) has a rupture membrane or a rupture disk, which is configured to at least partially open or release the opening (220) so that the electrolyte (190) can be at least partially discharged through the opening (220) when a certain overpressure is reached or exceeded in the cell housing (110).

8. An energy storage cell (100), comprising: A battery cell casing (110); Two electrodes (170, 175) arranged in the battery cell housing (110); The cap assembly (140) according to any one of the preceding claims, wherein the cap assembly (140) is fixed to the cell housing (110) such that the cell housing (110) is closed.

9. A battery module comprising a plurality of energy storage cells (100) according to claim 8. 10 . A motor vehicle having an electric drive or a hybrid drive and a battery module according to claim 9 .

11. A method for manufacturing a cap assembly (140), comprising the steps of: Providing an end plate (120) having a circular base and a longitudinal axis (L) extending perpendicular to the circular base; A substantially centrally arranged through-opening (220) is formed on the circular end plate (120) along the longitudinal axis (L); A groove (210) is formed on the surface of the circular end plate (120) so as to surround the longitudinal axis (L); Arranging a fixing component (200) in an edge region of the opening (220); A first closing element (230) is arranged for closing the opening (220), wherein The first closing element (230) is arranged to close the opening (220) in the installed state before the cell housing (110) is filled with an electrolyte (190) and to be penetrated, in particular pierced or penetrated, by a filling element for filling the cell housing (110), through which the electrolyte (190) can be filled into the cell housing (110); In the installed state and after the cell housing (110) has been filled, a second closing element (240) is arranged, which is provided to close the opening (220) after the cell housing (110) has been filled.

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