Simplified assembly of rupture membranes by stiffeners

Abstract

The invention relates to a membrane assembly comprising a rupture membrane and comprising at least one reinforcing frame, the reinforcing frame being connected to the rupture membrane, the reinforcing frame connected to the rupture membrane being designed to be inserted into a cell housing from the inside and to be connected to the cell housing from the outside by means of a thermal bonding method. The invention also relates to a method for connecting a rupture membrane to a battery cell housing, and to a battery cell having a membrane assembly.

Description

[0001] This invention relates to a membrane assembly comprising a burst membrane and at least one reinforcing frame. Furthermore, this invention relates to a method of connecting the burst membrane to a cell housing of a battery cell, and to a battery cell having the membrane assembly.

[0002] Electrochemical storage devices (e.g., lithium-ion batteries) may release gaseous components under certain conditions, creating overpressure within the cell casing. Excessive pressure within or on the battery cell casing can pose an explosion risk. Battery cells with integrated predetermined rupture points are known. For example, predetermined rupture points in the form of perforations can be incorporated into the wall of the battery cell casing to avoid dangerous overpressure.

[0003] Furthermore, it is known that rupture membranes are attached to the outside of the battery cell casing. However, the problem with attaching the rupture membrane, particularly by welding, is the need for a certain material thickness to reliably connect it to the corresponding part of the battery cell. Therefore, the rupture membrane is primarily arranged within the cell casing with sufficient material thickness to avoid this problem. The cell casing typically forms the highest point of the battery cell and also has electrical connections. However, depending on the arrangement and orientation of the cell stack, any generated gases can only be partially or incompletely dissipated through the cell casing. Furthermore, the electrical connections may hinder the formation of gas channels for removing gases from the battery cell. In particular, the rupture membrane integrated into the cell casing can only be hermetically coupled to external channels by increasing the workload, enabling the controlled discharge of gaseous components from a battery system with multiple battery cells.

[0004] Therefore, the object of the present invention is to create a membrane assembly and a method for connecting a rupture membrane, which enables the rupture membrane to be positioned technically and simply in the bottom side region of a cell housing, particularly an extruded or drawn cell housing. This object is achieved by the features specified in claim 1. Other advantageous embodiments of the invention are described in the dependent claims.

[0005] According to one aspect of the invention, a membrane assembly is provided. The membrane assembly has a rupture membrane and at least one reinforcing frame connected to the rupture membrane. According to the invention, the reinforcing frame connected to the rupture membrane is arranged to be inserted from the inside into a battery cell housing or a cell housing, and connected from the outside to the cell housing via a thermal bonding process.

[0006] According to another aspect of the invention, a battery cell is provided. The battery cell has a cell housing with at least one cell stack arranged within an internal volume of the cell housing. Furthermore, the battery cell has at least one membrane assembly according to the invention. Advantageously, the membrane assembly is arranged in a bottom side region of the cell housing.

[0007] This allows for the two-step attachment of the burst membrane to the particularly thin-walled battery cell housing. This measure also allows the burst membrane to be positioned in any area of ​​the cell housing, particularly in the bottom side region of the battery cell. In the first step, the burst membrane is attached to a reinforcing frame. This step can be performed using friction fits and / or material fits and / or form fits. For example, the burst membrane can be welded to the reinforcing frame. The resulting assembly can then be inserted into an opening provided for this purpose, or positioned at such an opening in the cell housing. Then, in the second step, the burst membrane can be attached to the cell housing using the additional material thickness formed by the reinforcing frame.

[0008] The rupture membrane can be welded to the wall of the cell casing via a reinforcing frame. The additional material thickness of the reinforcing frame enables a reliable process connection for any rupture membrane, eliminating the need to manufacture the rupture membrane separately as part of the battery cell production process.

[0009] By using a reinforced frame, joints (such as welds) can be placed in areas of the cell housing that do not perform any other function. This means, for example, that the outer surface or sealing surface of the cell housing used to house the seals can remain free of joints or welds to achieve a specially optimized sealing effect.

[0010] In another embodiment, the rupture membrane is plate-shaped. Advantageously, the rupture membrane rests on the edge of the reinforcing frame or is inserted into a recess in the reinforcing frame and is connected to the reinforcing frame. This allows the rupture membrane to be connected to the reinforcing frame in a particularly variety of ways.

[0011] The rupture membrane can be joined to the reinforcing frame using joining methods such as laser welding, ultrasonic welding, and brazing. Advantageously, at least one first joining connection can be introduced, which connects the rupture membrane to the reinforcing frame by material bonding. Such a first joining connection can, for example, take the form of a circumferential weld seam.

[0012] Then, at least one second bonding connection can be used to connect the membrane assembly to a section or wall of the cell housing.

[0013] In this configuration, the first joint connection can be offset from the second joint connection, at least in certain areas. Therefore, the openings in the cell housing and the rupture membrane can have different sizes, which increases the selection of suitable rupture membranes.

[0014] If the reinforcing frame is designed as a ring-shaped reinforcing frame, the rupture membrane can achieve optimal mechanical support. Advantageously, the reinforcing frame is bonded to the rupture membrane along its entire perimeter. This ensures a fluid-tight connection between the rupture membrane and the reinforcing frame.

[0015] According to another embodiment, the reinforcing frame has at least one locating pin. The reinforcing frame, connected to the rupture membrane, can be aligned with an opening in the cell housing via the at least one locating pin. Advantageously, at least one locating pin extends at least partially into the opening in the cell housing. The use of the locating pin facilitates the assembly of the membrane assembly and ensures precise alignment of the membrane assembly relative to the opening in the cell housing.

[0016] If the locating pin is designed as an annular locating pin, the alignment of the membrane assembly can be particularly precise. This annular locating pin is also shaped such that it is inserted into the opening and extends parallel to the edge profile of the opening of the cell housing. This design allows at least one second engagement connection to extend along the profile of the opening in the cell housing, thereby linking the profile of the opening to the locating pin via a material bond. This enables the reinforcing frame to be reliably attached to the cell housing using a specially engineered process. The orientation of the locating pin parallel to the profile of the opening provides particularly optimized tooling accessibility for the insertion of the second engagement connection.

[0017] If at least one reinforcing cage is arranged on the reinforcing frame, the membrane assembly can be further structurally reinforced or strengthened.

[0018] According to another embodiment, at least one reinforcing cage is arranged on the reinforcing frame on the inner side or the outer side of the cell housing. Arranging the reinforcing cage on the inner side of the cell housing effectively prevents obstruction of the area in front of the rupture membrane, thereby ensuring the protection mechanism of the rupture membrane at all times. Similarly, arranging the reinforcing cage on the outer side of the cell housing helps to keep the area outside the cell housing unobstructed, so that in the event of overpressure, the gaseous components of the battery cell can reliably escape through the rupture membrane.

[0019] If the reinforcing frame attached to the rupture membrane is configured to be connected to the outside of the cell housing directly or indirectly via at least one reinforcing cage using a thermal bonding process, then at least one reinforcing cage can be connected to the reinforcing frame particularly effectively. This allows the reinforcing frame to be connected to the cell housing while a joint connection (e.g., a weld) is formed in the area through the reinforcing cage.

[0020] According to another embodiment, the reinforcing frame has at least one edge bevel and / or stall edge. The edge bevel enables particularly optimized aerodynamic characteristics for fluid flowing out through an activated or ruptured membrane. The use of a stall edge can be used to convert fluid from a laminar to a turbulent state caused by overpressure from the battery cell, thereby increasing flow velocity and reducing overpressure more quickly.

[0021] According to another aspect of the invention, a method for attaching a burst membrane to a battery cell housing is provided. In one step, the burst membrane is aligned relative to a reinforcing frame, and the burst membrane is attached to the reinforcing frame by material bonding. In another step, the reinforcing frame attached to the burst membrane is positioned from the inside within the internal volume of the cell housing at an opening in the cell housing. The reinforcing frame is then bonded to the cell housing by applying a thermal bonding process to the outside of the cell housing in the opening region.

[0022] The method according to the invention ensures optimal tool accessibility to the respective joining joints during the application of the joining method. In particular, the method avoids introducing welds from inside the cell housing and the resulting need for particularly small or narrow tools. The method makes it possible to join the components by introducing joining joints on the outer surface (e.g., the outwardly pointing profile of the opening in the cell housing).

[0023] According to one embodiment, the reinforcing frame is joined to the cell housing via a thermal bonding process, such as laser welding, brazing, contact welding, or thermal activation bonding. Therefore, the introduction of the first and / or second bonding connections can be flexibly achieved by using different tools or bonding processes.

[0024] If the reinforcing frame attached to the rupture membrane is positioned from the inside within the internal volume of the cell housing at an opening in the cell housing by means of at least one locating pin, the membrane assembly can be inserted into the cell housing particularly easily. Specifically, if the locating pin is arranged adjacent to the edge profile of the opening in the cell housing, the membrane assembly can be inserted into the opening of the cell housing and optionally form a latching connection with the opening. Thus, if the membrane assembly is attached to the cell housing by a material bond, subsequent slippage of the membrane assembly can be prevented.

[0025] According to another embodiment, the reinforcing frame is connected to the cell housing by inserting at least one weld in the region between at least one locating pin and the edge profile of the opening in the cell housing. This measure reliably connects the region between the edge profile of the opening and the locating pin by inserting the weld. With this connection, the accuracy requirements for tool guidance are relatively low, making this connection particularly quick and technically simple to implement.

[0026] Several embodiments of the invention are explained in more detail below with reference to the accompanying drawings. The drawings show:

[0027] Figure 1 This is a schematic cross-sectional view of a membrane assembly according to an embodiment of the present invention.

[0028] Figure 2 It has Figure 1A schematic cross-sectional view of the bottom side region of the cell housing of the inserted membrane assembly of the battery cell.

[0029] Figure 3 This is a schematic cross-sectional view of the bottom side region of a cell housing having a membrane assembly according to a second embodiment of the present invention.

[0030] Figure 4 This is a schematic cross-sectional view of the bottom side region of a cell housing having a membrane assembly according to a third embodiment of the present invention.

[0031] Figure 5 This is a schematic cross-sectional view of the bottom side region of a cell housing having a membrane assembly according to a fourth embodiment of the present invention.

[0032] Figure 6 This is a schematic cross-sectional view of the bottom side region of a cell housing having a membrane assembly according to a fifth embodiment of the present invention, and

[0033] Figure 7 This is a schematic cross-sectional view of the bottom side region of a cell housing having a membrane assembly according to a sixth embodiment of the present invention.

[0034] In the accompanying drawings, the same reference numerals denote the same elements or structural components. The dimensions and relative positions of the elements in the drawings are not necessarily drawn to scale, and some of these elements are enlarged and positioned for clarity. Furthermore, the specific shapes of the elements drawn are not intended to convey any information about the actual shape of the individual elements, but are chosen solely for ease of identification in the drawings.

[0035] Figure 1 A schematic cross-sectional view of a membrane assembly 10 according to an embodiment of the present invention is shown. In the illustrated embodiment example, the membrane assembly 10 has a burst membrane 11 and a reinforcing frame 12. This cross-sectional view is used to illustrate the extension of the membrane assembly 10 along the width direction B and the height direction H.

[0036] The reinforcing frame 12 is connected to the rupture membrane 11 by a material bonding process. For this purpose, a first bonding connection 21 is introduced through the rupture membrane 11, which establishes a material bonding bonding connection between the reinforcing frame 12 and the rupture membrane 11. The arrows indicate the direction of action of the tool (not shown, e.g., a laser welding tool). The first bonding connection 21 can, for example, be designed as a circumferential weld.

[0037] The reinforcing frame 12 is designed as a ring frame and has a centrally located recess 13, which allows the burst membrane 11 to rupture or fold open into the recess 13 under excessive stress due to overpressure.

[0038] The reinforcing frame 12 connected to the burst membrane 11 is designed to be inserted into the battery cell housing or cell housing 30 from the inside and connected to the cell housing 30 from the outside via a thermal bonding process (see...). Figure 2 ).

[0039] The reinforcing frame 12 exemplarily has a positioning pin 14. The reinforcing frame 12, connected to the rupture membrane 11, can be engaged with the rupture membrane 11 via this positioning pin 14. Figure 2 The opening 33 of the cell housing 30 shown is aligned. The locating pin 14 extends into the opening 33 of the cell housing 30.

[0040] The locating pin 14 is annular or ring-shaped and surrounds the recess 13 of the reinforcing frame 12 on the circumferential side. The locating pin 14 is shaped such that when it is inserted into the opening 33 of the cell housing 30, it extends parallel to or along the edge profile of the opening 33 of the cell housing 30.

[0041] Figure 2 The insertion of the battery cell 100 is shown. Figure 1 A schematic cross-sectional view of the bottom side region 31 or bottom of the cell housing 30 of the membrane assembly 10. For clarity, other components of the battery cell 100, such as cell stacks, cell connectors, battery terminals, electrolyte, etc., are not shown.

[0042] The membrane assembly 10 is arranged in the bottom side region 31 such that the positioning pin 14, shaped as a positioning ring, extends precisely into the opening 33. Preferably, the entire reinforcing frame 12 is flat and flush with the inside of the bottom side region 31.

[0043] The opening 33 may have a circular, elliptical, rectangular, or similar cross-section. The membrane assembly 10 reinforces the bottom side region 31 of the cell housing 30. The membrane assembly 10 is connected to the bottom side region 31 of the cell housing 30 via an annular second joint connection 22. The second joint connection 22 is exemplarily designed as a weld.

[0044] Figure 2 The arrows in the diagram illustrate the effect of the joining tool (e.g., a laser welding tool) on the annular gap between the locating pin 14 and the contour of the opening 33 of the cell housing 30 from the outside.

[0045] In the illustrated embodiment example, the reinforcing frame 12 extends all the way to the sidewall 32 of the cell housing 30, thereby reinforcing the cell housing 30 on the bottom side.

[0046] Figure 3 A schematic cross-sectional view of the bottom side region 31 of a cell housing 30 is shown, the cell housing having a membrane assembly 10 according to a second embodiment of the present invention. Figure 2Compared to the example embodiment shown, the membrane assembly 10 here has additional structural reinforcement in the form of a reinforcing cage 40.

[0047] The reinforcing cage 40 surrounds the burst membrane 11 on the outside, and allows the burst membrane 11 to flow freely into the internal volume V of the cell housing 30.

[0048] exist Figure 4 In the alternative or additional embodiments shown, the membrane assembly 10 has a reinforcing cage 40 that is connected to the outside of the reinforcing frame 12. Thus, the reinforcing cage 40 maintains unobstructed access to the area outside the internal volume V of the cell housing 30.

[0049] In addition, the reinforcing cage 40 allows for additional reinforcement of the burst membrane 11 and the reinforcing frame 12.

[0050] exist Figure 4 In this configuration, the reinforcing frame 12 connected to the burst membrane 11 is also directly connected to the outside of the cell housing 30 via the reinforcing cage 40. In this way, a second joint connection 22 (e.g., a weld) can be introduced through a region or section of the reinforcing cage 40, which, in addition to connecting the reinforcing frame 12 to the cell housing 30, also connects the reinforcing frame 40 to the cell housing 30.

[0051] Figure 5 A schematic cross-sectional view of the bottom side region 31 of a cell housing 30, which has a membrane assembly 10 according to a fourth embodiment of the invention, is shown here. The cross-sectional view is shown here to illustrate the extension of the membrane assembly 10 along the longitudinal direction L, compared to the figures already described.

[0052] To achieve particularly effective reinforcement or strengthening of the bottom side region 31, the reinforcing frame 12 extends beyond the opening 33 on one side and extends substantially over the entire bottom side region 31 of the cell housing 30 along its longitudinal direction L.

[0053] For clarity, Figure 5 , Figure 6 and Figure 7 The connecting parts 21 and 22 are not shown in the figure.

[0054] exist Figure 6 The image shows a cross-sectional view of the bottom side region 31 of a cell housing 30, which has a membrane assembly 10 according to a fifth embodiment of the invention. In this embodiment, the reinforcing frame 12 has at least one edge-side bevel 41.

[0055] This edge bevel 41 can improve the aerodynamic characteristics of the fluid flowing out of the rupture membrane 11 due to overpressure. This fluid may contain both gaseous and liquid components of the electrolyte, as indicated by the arrows.

[0056] According to such Figure 7 The sixth embodiment shown illustrates another membrane assembly 10 with a reinforcing frame 12. The reinforcing frame 12 has a stall edge 42.

[0057] The stall edge 42 is substantially perpendicular to the bottom side region 31 and thus extends into the internal volume V of the cell housing 30. Depending on the configuration, the stall edge 42 can be arranged at the edge in the longitudinal direction L of the reinforcing frame 12 to force the fluid to stall and form turbulence when fluid is generated.

[0058] and Figure 6 Similarly, this fluid is generated due to the activation or rupture of the bursting membrane 11 caused by pressure exceeding a predetermined pressure within the internal volume V of the cell housing 30. Therefore, this fluid consists of components escaping from the cell housing 30, as indicated by the arrows.

Claims

1. A membrane module (10) having a burst membrane (11) and at least one reinforcing frame (12), wherein, The reinforcing frame (12) is connected to the bursting membrane (11), characterized in that the reinforcing frame (12) connected to the bursting membrane (11) is designed to be inserted into the cell housing (30) from the inside and connected to the cell housing (30) of the battery cell (100) from the outside by a thermal bonding process.

2. The membrane module according to claim 1, wherein, The bursting membrane (11) is plate-shaped, wherein the bursting membrane (11) rests on the edge of the reinforcing frame (12) or is placed in the recess of the reinforcing frame (12), and the bursting membrane (11) is connected to the reinforcing frame (12).

3. The membrane module according to claim 1 or 2, wherein, The reinforcing frame (12) is designed as a ring-shaped reinforcing frame (12), wherein the reinforcing frame (12) is connected to the burst membrane (11) in a material-locking manner along the entire periphery.

4. The membrane module according to any one of claims 1 to 3, wherein, The reinforcing frame (12) has at least one locating pin (14), wherein the reinforcing frame (12) connected to the burst membrane (11) is alignable with the opening (33) of the cell housing (30) via the at least one locating pin (14), wherein the at least one locating pin (14) extends at least partially into the opening (33) of the cell housing (30).

5. The membrane module according to claim 4, wherein, The positioning pin (14) is designed as an annular positioning pin (14), wherein the annular positioning pin (14) is shaped such that it extends parallel to the edge profile of the opening (33) when it is inserted into the opening (33) of the cell housing (30).

6. The membrane module according to any one of claims 1 to 5, wherein, At least one reinforcing cage (40) is arranged on the reinforcing frame (12).

7. The membrane module according to claim 6, wherein, The at least one reinforcing cage (40) is arranged on the reinforcing frame (12) on the inner side of the cell housing (30) or on the outer side of the cell housing (30).

8. The membrane module according to claim 6 or 7, wherein, The reinforcing frame (12) connected to the burst membrane (11) is designed to be connected to the cell housing (30) directly from the outside or indirectly via the at least one reinforcing cage (40) by a thermal bonding process.

9. The membrane module according to any one of claims 1 to 8, wherein, The reinforcing frame (12) has at least one edge side bevel (41) and / or stall edge (42).

10. A method for connecting a bursting membrane (11) to a cell housing (30), particularly a cell housing (30) of a battery cell (100), wherein, The bursting membrane (11) is aligned with the reinforcing frame (12) and connected to the reinforcing frame (12) in a material-locking manner. The reinforcing frame (12) connected to the bursting membrane (11) is positioned from the inside in the internal volume (V) of the cell housing (30) at the opening (33) of the cell housing (30), and the reinforcing frame (12) is connected to the cell housing (30) in a material-locking manner by applying a thermal bonding process to the outside of the cell housing (30) in the region of the opening (33).

11. The method according to claim 10, wherein, The reinforcing frame (12) is joined to the cell housing (30) by a thermal bonding method in a material-locking manner, the thermal bonding method being configured as laser welding, brazing, contact welding, or thermally activated bonding.

12. The method according to claim 10 or 11, wherein, The reinforcing frame (12) connected to the burst membrane (11) is positioned from the inside in the internal volume (V) of the cell housing (30) by means of at least one locating pin (14) at the opening (33) of the cell housing (30), wherein the locating pin (14) is arranged adjacent to the edge profile of the opening (33) of the cell housing (30).

13. The method according to claim 12, wherein, The reinforcing frame (12) is connected to the cell housing (30) by introducing at least one weld in the region between the at least one locating pin (14) and the edge profile of the opening (33) of the cell housing (30).

14. A battery cell (100) comprising a cell housing (30) having at least one cell stack, and including a membrane assembly (10) according to any one of claims 1 to 9, wherein the cell stack is arranged in an internal volume (V) of the cell housing (30), wherein, The membrane assembly (10) is arranged in the bottom side region (31) of the cell housing (30).

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