Cover assembly, energy storage cell, battery module and method for producing a cover assembly

Abstract

The invention relates to a cover assembly for a cell housing of an energy storage cell, wherein, in the installed state, the cover assembly is designed so as to enable the cell housing to be filled with an electrolyte, the cover assembly comprising: (i) an end plate with an attachment assembly, which comprises an opening, (ii) wherein the end plate also comprises a circumferential groove; (iii) a first closure element, which is designed to close the opening, before filling of the cell housing, and to be penetrated by a filling element for filling the cell housing, through which the electrolyte can be filled into the cell housing; (iv) a second closure element which is designed to close the opening after filling of the cell housing; (v) wherein the circumferential groove is designed to enable the end plate to break open in the region of the groove if a certain excess pressure is reached or exceeded in the cell housing, so that an at least partial escape of the electrolyte is enabled through the broken open region.

Description

[0001] COVER ASSEMBLY, ENERGY STORAGE CELL, BATTERY MODULE AND METHOD FOR MANUFACTURING A COVER ASSEMBLY

[0002] The present invention relates to a cover assembly, an energy storage cell, a battery module and a method for producing a cover assembly.

[0003] In the field of energy storage cells, especially battery cells, especially lithium-ion battery cells, cylindrical, prismatic, and pouch-shaped battery cells are the most common. Battery cells for storing electrical energy play a central role in the field of electromobility, both in purely electric vehicles and in hybrid vehicles. For example, a battery module for a 12V starter battery can have four battery cells, whereas a high-voltage storage system can have several battery modules.

[0004] Battery cells can contain an energy storage device and associated electrodes within a cell housing. Electrical power can be tapped from outside the cell housing via electrical connections to the electrodes. The energy storage device can contain chemical compounds that can lead to gas emissions within the cell housing. At high temperatures, high pressure can build up within the cell housing, increasing the risk of thermal runaway of the battery cell.

[0005] It is an object of the present disclosure to provide a cover assembly, an energy storage cell, a battery module, a motor vehicle and a method for producing a cover assembly which is improved with regard to the above-mentioned problems.

[0006] This object is achieved by a cover assembly according to claim 1, an energy storage cell, a battery module, a motor vehicle and a method for producing a cover assembly.

[0007] A first aspect of the solution relates to a cover assembly for a cell housing of an energy storage cell, wherein the cover assembly, in the installed state, is configured to enable filling of the cell housing with an electrolyte, wherein the cover assembly comprises: (i) a cover plate with a fastening assembly having an opening, (ii) wherein the cover plate further comprises a circumferential groove; (iii) a first closure element, which is configured to close the opening before filling the cell housing and to be penetrated by a filling element through which the electrolyte can be filled into the cell housing for filling the cell housing; (iv) a second closure element, which is configured to close the opening after filling the cell housing;(v) wherein the circumferential groove is designed to enable the end plate to be broken open in the region of the groove when a certain overpressure has been reached or exceeded in the cell housing, so that at least partial escape of the electrolyte through the broken open region is possible;

[0008] The terms "comprises," "includes," "includes," "has," "has," "with," or any other variation thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a method or apparatus that includes or has a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or that are inherent in such a method or apparatus.

[0009] Furthermore, unless explicitly stated otherwise, "or" refers to an inclusive "or" and not an exclusive "or." For example, a condition A or B is satisfied by one of the following conditions: A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), and both A and B are true (or present).

[0010] The terms "a" or "an" as used herein are defined to mean "one or more." The terms "another" and "another," and any other variations thereof, are defined to mean "at least one more." The term "plural," as used herein, is defined to mean "two or more."

[0011] The term “configured” or “set up” to fulfil a specific function (and respective variations thereof) as used here is to be understood to mean that the corresponding device is already in a design or setting in which it can carry out the function or is at least adjustable - i.e. configurable - so that it can carry out the function after being set accordingly. The configuration can be carried out, for example, by appropriately setting parameters of a process sequence or of switches or similar for activating or deactivating functionalities or settings. In particular, the device can have a plurality of predetermined configurations or operating modes, so that the configuration can be carried out by selecting one of these configurations or operating modes.

[0012] The term "electrode coil" as used here refers in particular to a device which, as an assembly of a galvanic cell, in particular a battery cell, also serves to store chemical energy and release electrical energy. For this purpose, the electrode coil comprises at least two electrodes, namely an anode and a cathode, and a separator, in particular an electrically insulating separator, which can at least partially accommodate an electrolyte. The anode, separator, and cathode are wound around an axis to form an electrode coil. Before electrical energy is released, stored chemical energy is converted into electrical energy. During charging of the 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.

[0013] The term "separator layer" or "separator" as used here refers in particular to an electrically insulating device that separates and spaces an anode from a cathode. Preferably, a separator layer is applied to an anode layer and / or a cathode layer. Preferably, the separator layer is formed as an independent body. The separator layer or separator can also at least partially accommodate an electrolyte, wherein the electrolyte preferably contains lithium ions. The electrolyte can also be electrochemically bonded to adjacent layers of the electrode stack. Preferably, the shape of a separator essentially corresponds to the shape of an anode of the electrode stack. Preferably, a separator is thin-walled, particularly preferably as a microporous film. Preferably, the separator layer or separatorThe separator is wetted with an additive that also increases the mobility of the separator layer or separator. Wetting is particularly preferably carried out with an ionic additive. The separator layer or separator preferably extends at least partially over a boundary edge of at least one electrode. The separator layer or separator particularly preferably extends beyond all boundary edges of adjacent electrodes.

[0014] The term "electrolyte" as used here refers in particular to a liquid or solid material through which ions can be conducted, enabling current transport between the electrodes of a battery, in particular between a cathode and an anode. Unlike electronic conductivity (through electrons) in the electrode materials, the electrolyte must be ionically conductive, i.e., conduct electrical current by transporting charged atoms or molecules (ions). The electrolyte is advantageously chemically stable over a wide temperature range and electrochemically stable against decomposition over the largest possible voltage range. Ideally, it is non-toxic and non-flammable and possesses at least a high flash point and low heat of combustion. Liquid systems may be preferred over polymer and solid electrolytes due to their better conductivity.

[0015] The energy storage cell according to the first aspect makes it possible for the cover assembly to rupture in the region of the circumferential groove when a certain pressure in the cell housing is reached or exceeded when the cover assembly is installed on a cell housing of an energy storage cell. This can prevent the pressure currently prevailing in the cell housing from rising further. This preferably achieves controlled, directed, and thus safe pressure relief. The cover assembly therefore not only enables reliable and safe electrolyte filling under normal conditions, but also serves to relieve any excess pressure that may occur in the cell, for example as a result of strong heating due to internal cell short circuits. Furthermore, the cover assembly can be manufactured separately from the cell housing.This can be advantageous when assembling the cover assembly onto the cell housing, as the opening, the first closure element, the fastening assembly, and the groove can already be arranged or formed before the cover assembly is attached to the cell housing. Only the second connection element closes the opening after the electrolyte has been filled. Forming the opening, for example, by drilling, when the cover assembly is already attached to the cell housing can lead to contaminants, particularly metal chips, entering the cell housing, which can impair 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 be combined with each other as well as with the other aspects described, unless this is expressly excluded or is technically impossible.

[0017] In some embodiments, the first closure element comprises a membrane and / or a film which is arranged in the opening. A membrane or film is preferably understood to be any thin, flat structure made of plastic, rubber, metal or other materials, or a combination of two or more different materials, which has a large surface area in relation to its thickness. This makes it possible to achieve, on the one hand, good sealing of the opening and, on the other hand, good penetrability of the first closure element. The membrane or film is preferably made of an elastic material. This makes it possible to ensure that no or only a relatively small amount of electrolyte or solvent escapes at the point at which the filling element penetrates the membrane or film.

[0018] In some embodiments, the first closure element is designed to be pierced and / or penetrated by a filling element designed as a hollow needle in order to fill the cell housing. This allows filling of a closed cell housing. In some embodiments, the second closure element is designed to be connected to the fastening assembly in a force-fitting manner, in particular by screwing, in order to close the opening, in particular to seal it hermetically. For example, the opening can be provided with an internal thread and the second closure element with an external thread, such that the second closure element can be screwed into the opening. This makes it particularly easy to reliably seal the opening after the energy storage cell has been filled.

[0019] In some embodiments, the second closure element is designed to be connected to the fastening assembly in a materially bonded manner, in particular by welding and / or soldering, in order to close the opening, in particular to seal it hermetically. For example, flanges can be provided on the second closure element for this purpose, which are welded or soldered to the fastening assembly of the filling connection. This also allows for a reliable sealing of the opening after filling the cell in a simple manner.

[0020] In some embodiments, the first closure element is detachably mounted in the opening, so that the first closure element can be at least partially removed, in particular pushed out, from the opening by the excess pressure. For example, a circumferential groove can be provided in the opening, in which the first closure element is held. If the excess pressure in the cell exceeds a certain value, the first closure element is released from the circumferential groove of the opening, thereby reducing excess pressure in the cell housing.

[0021] In some embodiments, the second closure element comprises a bursting membrane or bursting disc which is configured to at least partially open or release the opening in order to allow at least partial escape of the electrolyte through the opening when a certain overpressure is reached or exceeded in the cell housing. A bursting membrane or bursting disc consists of a suitable material, such as aluminum, an aluminum alloy, steel or PTFE, and is designed such that it can burst and / or release the opening if a certain overpressure in the cell is reached or exceeded. This preferably achieves a controlled, directed and therefore safe pressure relief. The cover assembly thus enables any overpressure that may occur in the cell, for example as a result of strong heating due to short circuits within the cell, to be reduced.

[0022] 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; (iii) a cover assembly according to the first aspect, wherein the cover assembly is attached to the cell housing such that the cell housing is closed, in particular gas-tight.

[0023] A third aspect of the solution relates to a battery module with a plurality of energy storage cells according to the second aspect.

[0024] A fourth aspect of the solution relates to a motor vehicle with an electric drive or a hybrid drive and a battery module according to the third aspect.

[0025] A fifth aspect of the solution relates to a method for producing a cover assembly according to the first aspect, comprising the steps: (i) providing an end plate with a circular base and a longitudinal axis (L) running perpendicular to the circular base; (ii) forming a substantially centrally arranged through opening along the longitudinal axis on the circular end plate; (iii) forming a groove circumferential with respect to the longitudinal axis on a surface of the circular end plate; (iv) arranging a fastening assembly in the edge region of the opening;(v) Arranging a first closure element for closing the opening, wherein the first closure element is configured, in the installed state, to close the opening before filling the cell housing with an electrolyte and, in order to fill the cell housing, to be penetrated, in particular pierced or punctured, by a filling element through which the electrolyte can be filled into the cell housing; (vi) Arranging a second closure element in the installed state and following the filling of the cell housing, which is configured to close the opening after filling the cell housing. The features and advantages explained with regard to the first aspect of the solution also apply accordingly to the further aspects described.

[0026] Further advantages, features and possible applications emerge from the following description of preferred embodiments in conjunction with the figures.

[0027] This shows

[0028] Fig. 1 schematically shows a battery cell according to an embodiment;

[0029] Fig. 2 schematically shows a cover assembly according to an embodiment;

[0030] Fig. 3A to 3D schematically show manufacturing states of a cover assembly according to an embodiment; and

[0031] Fig. 4 is a flow chart illustrating a preferred embodiment of a method for producing a battery cell.

[0032] Throughout the figures, the same reference numerals are used for the same or corresponding elements.

[0033] Figure 1 schematically shows a battery cell 100 according to one embodiment. The battery cell 100 has a hollow cylindrical cell housing 110 with a longitudinal axis L. The cell housing 110 can also be cuboid-shaped. The cell housing 110 comprises an electrically conductive material. However, it is also conceivable for the cell housing 110 to comprise an electrically insulating material. The cell housing 110 is closed on one side by a base plate 130. On a side opposite 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 described in more detail in Figure 2. The end plate 120 is arranged in a circumferential groove of the cell housing 110, wherein an electrically insulating 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 electrically insulating element 150 acts as a gas seal, so that the cell housing 110 can be sealed gas-tight by the cover assembly 140. The opening of the groove points toward the longitudinal axis L.

[0034] However, it is also conceivable that no electrically insulating element 150 is arranged between the end plate 120 and the groove. This can be useful if the cell housing 110 comprises an electrically insulating material. Furthermore, it is conceivable that an electrode of one polarity is guided through the base plate 130 of the cell housing 110, with the feedthrough being electrically insulated from the cell housing 110 and also being incorporated into the base plate 130. In this case, too, the cover can be connected directly to the cell housing 110, in particular by welding.

[0035] An electrode coil 160 is arranged in the cell housing 110. The electrode coil 160 has electrodes with a first, positive, polarity 170 and electrodes with a second, negative, polarity 175. However, the electrode coil 160 can also be constructed such that the first polarity is negative and the second polarity is positive. The electrode coil 160 is arranged in the cell housing 110 such that electrodes with a positive polarity 170 and electrodes with a negative polarity 175 are arranged alternately in the radial direction. A separator 180 is arranged between each of the positively polarized electrodes 170 and the negatively polarized electrodes 175, so that the differently polarized electrodes 170, 175 are electrically insulated from one another, wherein the separator 180 comprises an electrically insulating material. Furthermore, an electrolyte 190 is schematically shown in the cell housing 110. The electrolyte 190 is filled into the cell housing 110 through the lid assembly 140.

[0036] Figure 2 schematically shows 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 running circumferentially with respect to a longitudinal axis L. The groove 210 has a triangular cross-section. The cross-section can also have a semicircle, a rectangle, or another shape. The end plate 120 has a smaller thickness in the region of the groove 210 than the thickness of the end plate 120 during its manufacture, and can therefore break open more easily in these areas. The end plate 120 has a fastening assembly 200 with an opening 220 arranged substantially centrally with respect to the end plate 120. The fastening assembly 200 is arranged symmetrically to the longitudinal axis L.The fastening assembly 200 has a first support ring 203 arranged on one side of the end plate 120 and a second support ring 207 arranged on another side of the end plate 120. The opening 220 is closed by a membrane 230. Likewise, a film can close the opening 220 instead of the membrane 230. An electrolyte 190 can be filled into the cell housing 110 through the membrane 220 using a filling tool, in particular a hollow needle (not shown here) that is suitable for piercing the membrane 230. After filling and withdrawing the filling tool from the cell housing 110 and the membrane 230, the membrane 230 closes. This closure is intended to prevent significant amounts of the electrolyte 190 from escaping from the cell housing 110. Especially with electrolytes 190, whose boiling point is below room temperature, boiling off can occur.However, sealing the 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 may be made of metal and is attached to the mounting assembly 200 in a gas-tight manner.

[0037] In the event of overpressure within the closed cell housing 110, the closure plate 120 is designed to break open in the region of the groove 210. This allows gas or the electrolyte 190 to escape from the cell housing 110, preventing further pressure buildup.

[0038] Figures 3A to 3D schematically show manufacturing states of a cover assembly according to one embodiment.

[0039] Figure 3A shows a side view of an end plate 120 having a longitudinal axis L. In the side view of the end plate 120, the longitudinal axis L runs substantially perpendicular to the end plate 120.

[0040] In Figure 3B, the end plate 120 has a substantially centrally arranged opening 220. A first support ring 203 is fastened to one side of the opening 220. The fastening is preferably formed by a material fit. The first support ring 203 is arranged axially symmetrically to the longitudinal axis L. The end plate 120 further has a circumferential groove 210, which is arranged radially further outward 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.

[0041] Figure 3C shows an arrangement according to Figure 3B, wherein a second support ring 207 is additionally attached to another side of the opening 220. This attachment is also preferably formed with a material fit. As a result, the membrane 230 is arranged between the first support ring 203 and the second support ring 207.

[0042] The arrangement shown in Figure 3D corresponds to the arrangement of Figure 2. In comparison to Figure 3C, a cover 240 is attached to the upper region of the fastening assembly 200 with respect to the plane of the drawing.

[0043] It is also conceivable that, instead of the first support ring 203 and the second support ring 207, the fastening assembly 200 is formed in one piece and forms a circumferential groove. The groove is open at one section so that the membrane 230 can be arranged in the groove. The membrane 230 is preferably deformable. This opening can then be closed by mechanical deformation. The one-piece fastening assembly 200 can accordingly be firmly attached to an inner side of the opening 220 (not shown here).

[0044] Figure 4 shows a flow chart 400 illustrating one embodiment of a method for manufacturing a cover assembly 140 of one embodiment.

[0045] In a first step 410 of the method, a cover plate 120 having a circular base area and a longitudinal axis L running perpendicular to the circular base area is provided.

[0046] In a further step 420 of the method, a substantially centrally arranged through opening 220 is formed along the longitudinal axis L on the circular end plate 120. The opening 220 can be formed in particular by a drilling step.

[0047] In a further step 430 of the method, a circumferential groove 210 is formed on a surface of the circular end plate 120 with respect to the longitudinal axis L. The circumferential groove 210 can be formed in particular by milling or laser engraving.

[0048] In a further step 440 of the method, a fastening assembly 200 is arranged in the edge region of the opening 220. In particular, the fastening assembly 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 fastened to the end plate 120 and the other support ring 203, 207 is provided.

[0049] In a further step 450 of the method, a membrane 230 is arranged to close the opening 220. The membrane 230 is configured, in the installed state, to close the opening 220 before filling the cell housing 110 with an electrolyte 190 and to be penetrated, in particular pierced or punctured, by a filling element through which the electrolyte 190 can be filled into the cell housing 110 in order to fill the cell housing 110. When closing the opening, the membrane 230 is placed on the support element 203, 207 that is attached to the end plate 120.

[0050] In a further step 460, the other support ring 203, 207 that was provided is placed under contact pressure at the opening 220. This other support ring 203, 207 is then materially connected to the end plate 120, so that the membrane 230 is arranged between the two support rings 203, 207. It is also conceivable that one of the support rings 203, 207 or both support rings 203, 207 are force-fitted to the end plate 120. The materially connected connection can be achieved by a welding process, and the force-fit connection can be achieved by a screw connection. In a further step 470 of the method, a cover 240 is arranged in the installed state and following the filling of the cell housing 110, which cover is configured to close the opening 220 after the filling of the cell housing 110.While at least one exemplary embodiment has been described above, it should be appreciated that a large number of variations exist. It should also be understood that the described exemplary embodiments are only non-limiting examples and are not intended to limit the scope, applicability, or configuration of the devices and methods described herein. Rather, the foregoing description will provide those skilled in the art with a guide for implementing at least one exemplary embodiment, it being understood that various changes in the operation and arrangement of the elements described in an exemplary embodiment may be made without departing from the subject matter defined in the appended claims, as well as their legal equivalents.

[0051] LIST OF REFERENCE SYMBOLS

[0052] 100 battery cells

[0053] 110 cell casings

[0054] 120 end plate

[0055] 130 base plate

[0056] 140 cover assembly

[0057] 150 Insulating element

[0058] 160 electrode coils

[0059] 170 electrodes with positive polarity

[0060] 175 electrodes with negative polarity

[0061] 180 Separator

[0062] 190 Electrolyte

[0063] 200 mounting assembly

[0064] 203 First support ring

[0065] 207 Second support ring

[0066] 210 groove

[0067] 220 opening

[0068] 230 membrane

[0069] 240 lids

[0070] 400 Flowchart illustrating an embodiment of a method for manufacturing a cover assembly

[0071] 410 Providing a cover plate

[0072] 420 Forming a substantially centrally arranged through opening

[0073] 430 Forming a circumferential groove

[0074] 440 Arranging a mounting assembly

[0075] 450 Arranging a membrane

[0076] 460 Connecting the mounting assembly

[0077] 470 Arranging a lid

Claims

CLAIMS Cover assembly (140) for a cell housing (110) of an energy storage cell (100), wherein the cover assembly (140) in the installed state is configured to enable the cell housing (110) to be filled with an electrolyte (190), wherein the cover assembly (140) comprises: a cover plate (120) with a fastening assembly (200) which has an opening (220); wherein the cover plate (120) further comprises a circumferential groove (210); a first closure element (230) which is configured to close the opening (220) before the cell housing (110) is filled and to be penetrated by a filling element through which the electrolyte (190) can be filled into the cell housing (110) for filling the cell housing (110); a second closure element (240) which is adapted to close the opening (220) after filling the cell housing (110);wherein the circumferential groove (210) is configured to enable the end plate (120) to be broken open in the region of the groove (210) when a certain overpressure has been reached or exceeded in the cell housing (110), such that at least partial escape of the electrolyte (190) through the broken open region is possible. Cover assembly (140) according to claim 1, wherein the first closure element (230) comprises a membrane and / or a film which is mounted in the opening (220). Cover assembly (140) according to claim 1 or 2, wherein the first closure element (230) is configured to be pierced and / or penetrated by a filling element designed as a hollow needle in order to fill the cell housing (110). The lid assembly (140) according to any one of the preceding claims, wherein the second closure element (240) is configured to be force-fitted to the fastening assembly (200) to close the opening (220). The cover assembly (140) according to any one of the preceding claims, wherein the second closure element (240) is configured to be integrally connected to the fastening assembly (200) in order to close the opening (220). The cover assembly (140) according to any one of the preceding claims, wherein the first closure element (230) is detachably mounted in the opening (220) such that the first closure element (230) can be at least partially removed from the opening (220) by the overpressure. The cover assembly (140) according to any one of the preceding claims, wherein the second closure element (240) comprises a bursting membrane or bursting disk configured to at least partially open or release the opening (220) in order to allow at least partial escape of the electrolyte (190) through the opening (220) when a specific overpressure is reached or exceeded in the cell housing (110).An energy storage cell (100), comprising: a cell housing (110); two electrodes (170, 175) arranged in the cell housing (110); a cover assembly (140) according to any one of the preceding claims, wherein the cover assembly (140) is fastened to the cell housing (110) such that the cell housing (110) is closed. A battery module with a plurality of energy storage cells (100) according to claim 8. A motor vehicle with an electric drive or a hybrid drive and a battery module according to claim 9. A method for producing a cover assembly (140), comprising the following steps: Providing an end plate (120) having a circular base and a longitudinal axis (L) perpendicular to the circular base; Forming a substantially centrally arranged through opening (220) along the longitudinal axis (L) on the circular end plate (120); Forming a groove (210) circumferential with respect to the longitudinal axis (L) on a surface of the circular end plate (120); Arranging a fastening assembly (200) in the edge region of the opening (220); Arranging a first closure element (230) for closing the opening (220), wherein the first closure element (230) is designed 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 punctured, by a filling element through which the electrolyte (190) can be filled into the cell housing (110) in order to fill the cell housing (110); Arranging a second closure element (240) in the installed state and following the filling of the cell housing (110), which is designed to close the opening (220) after the filling of the cell housing (110).

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