Simplified mounting of a bursting membrane by reinforcement

Abstract

The invention relates to a membrane assembly, comprising a bursting membrane and comprising at least one reinforcing frame, wherein the reinforcing frame is connected to the bursting membrane, wherein the reinforcing frame connected to the bursting membrane is designed to be inserted into a cell housing on the inside and to be connected to the cell housing on the outside by a thermal joining method. The invention further relates to a method for connecting a bursting membrane to a battery cell housing, and to a battery cell having a membrane assembly.

Description

[0001] SIMPLIFIED ASSEMBLY OF A BURST MEMBRANE THROUGH REINFORCEMENT

[0002] The invention relates to a membrane assembly comprising a bursting membrane and at least one reinforcement frame. Furthermore, the invention relates to a method for connecting a bursting membrane to a cell housing of a battery cell, as well as to a battery cell comprising a membrane assembly.

[0003] Electrochemical storage devices, such as lithium-ion batteries, can release gaseous components under certain conditions, thus building up excess pressure in the cell casing. Excessive pressure within a battery cell casing or cell housing can result in an explosion hazard. Battery cells with integrated predetermined breaking points are already known. For example, predetermined breaking points can be introduced in the form of punched holes in the walls of battery cell casings to prevent potentially hazardous overpressure.

[0004] Furthermore, bursting membranes are already known which are connected externally to a cell housing cover of a battery cell. A problem with externally connecting bursting membranes, particularly by welding, is the need for a certain material thickness to enable a reliable connection of the bursting membrane to the corresponding section of the battery cell. For this reason, bursting membranes are predominantly arranged in a cell cover with a sufficient material thickness to avoid this problem. The cell cover usually forms the highest point of the battery cell and also has electrical connections. Depending on the arrangement and orientation of the cell stack, however, any gases produced may only be inadequately or not completely discharged via the cell cover. Furthermore, the electrical connections can impair the formation of a gas channel for discharging gases from the battery cells.In particular, a bursting membrane incorporated into a cell lid can only be coupled gas-tight to external channels with increased effort in order to enable a controlled discharge of gaseous components from a battery system with a large number of battery cells.

[0005] The present invention therefore aims to provide a membrane assembly and a method for connecting a bursting membrane that enable technically simple positioning of the bursting membrane in a bottom region of a cell housing, particularly an extruded or drawn one. This object is achieved by the features specified in claim 1. Further advantageous embodiments of the invention are part of the subclaims.

[0006] According to one aspect of the invention, a membrane assembly is provided. The membrane assembly comprises a bursting membrane and at least one reinforcing frame connected to the bursting membrane.

[0007] According to the invention, the reinforcement frame connected to the bursting membrane is designed to be inserted into a battery cell housing or cell housing on the inside and to be connected to the cell housing on the outside by a thermal joining process.

[0008] According to a further aspect of the invention, a battery cell is provided. The battery cell comprises a cell housing with at least one cell stack arranged in an interior volume of the cell housing. Furthermore, the battery cell comprises at least one membrane arrangement according to the invention. The membrane arrangement is advantageously arranged in a bottom region of the cell housing.

[0009] This allows for the bonding of bursting membranes to particularly thin-walled battery cell housings in two steps. This measure also enables the arrangement of the bursting membrane in any area of ​​the cell housing, in particular in a base area of ​​the battery cell. The base area or the base-side area of ​​the battery cell refers to a relative position in an installed state of the battery cell. The battery cell can thus be placed or placed on the base area in an assembled or installed state, for example, within a housing of a battery system or battery module. The base area is preferably oriented in the direction of gravity or towards a subsurface.

[0010] In a first step, the bursting membrane is connected to the reinforcement frame. This step can be performed using a frictional and / or material-locking and / or positive-locking connection. For example, the bursting membrane can be welded to the reinforcement frame. The resulting assembly can then be inserted into a designated opening or positioned at such an opening in the cell housing. The additional material thickness created by the reinforcement frame can then be used to connect the bursting membrane to the cell housing in a second step.

[0011] The bursting membrane can be welded to a wall of the cell casing via the reinforcement frame. The additional material thickness of the reinforcement frame enables a reliable connection of any bursting membrane, eliminating the need for separate manufacturing of bursting membranes during battery cell production.

[0012] By using the reinforcement frame, a joint, such as a weld seam, can be relocated to an area of ​​the cell housing that no longer serves any other function. This allows sealing surfaces or outer surfaces of the cell housing for accommodating seals to be kept free of joints or weld seams, achieving a particularly optimal sealing effect.

[0013] In another embodiment, the bursting membrane is plate-shaped. Advantageously, the bursting membrane rests on the edge of the reinforcement frame or is inserted into a recess in the reinforcement frame and connected to the reinforcement frame. This measure allows the bursting membrane to be connected to the reinforcement frame in a particularly versatile manner.

[0014] Joining methods such as laser welding, ultrasonic welding, soldering, and the like can be used to connect the bursting membrane to the reinforcement frame. Advantageously, at least one first joint can be introduced, which firmly connects the bursting membrane to the reinforcement frame. Such a first joint can, for example, be designed in the form of a circumferential weld seam.

[0015] The membrane arrangement can then be connected to a section or wall of a cell housing by means of at least one second joining connection.

[0016] The first joint can be offset locally, at least in some areas, from the second joint. This allows the opening of the cell housing and the bursting membrane to have different sizes, thereby expanding the range of usable bursting membranes.

[0017] The bursting membrane can be mechanically supported particularly optimally if the reinforcement frame is designed as a circumferential reinforcement frame. Advantageously, the reinforcement frame is firmly bonded to the bursting membrane along its entire circumference. This ensures a fluid-tight connection between the bursting membrane and the reinforcement frame.

[0018] According to a further embodiment, the reinforcement frame has at least one positioning pin. The reinforcement frame connected to the bursting membrane can be aligned with an opening in the cell housing by means of the at least one positioning pin. Advantageously, the at least one positioning pin protrudes at least partially into the opening in the cell housing. The use of the positioning pin enables easier assembly of the membrane assembly and precise alignment of the membrane assembly with respect to the opening in the cell housing.

[0019] The membrane arrangement can be aligned particularly precisely if the positioning pin is designed as a circumferential positioning pin. The circumferential positioning pin is further shaped such that, when inserted into the opening, it runs parallel to an edge contour of the opening in the cell housing. This measure allows the at least one second joining connection to run along the contour of the opening in the cell housing, thus firmly bonding the contour of the opening to the positioning pin. This allows the reinforcement frame to be connected to the cell housing with particularly reliable processing. The parallel course of the positioning pin to the contour of the opening enables particularly optimal tool access for inserting the second joining connection.

[0020] The membrane assembly can be further structurally stiffened or reinforced if at least one reinforcement cage is arranged on the reinforcement frame. The reinforcement cage can have a structure or ribs designed to keep a flow cross-section clear. In particular, this allows a distance between the bursting membrane and other elements, such as electrode stacks arranged in the interior volume of the cell housing or components arranged externally or outside the interior volume of the cell housing, to be adjusted and maintained.

[0021] According to a further embodiment, the at least one reinforcement cage is arranged on the inside of the cell housing or on the outside of the cell housing on the reinforcement frame. Arranging the reinforcement cage on an inside of the cell housing can efficiently prevent blockage of an area in front of the bursting membrane, so that the protective mechanism of the bursting membrane can always be ensured. Arranging the reinforcement cage on an outside of the cell housing can be used analogously to keep an area outside the cell housing clear, enabling reliable escape of gaseous components of the battery cell via the bursting membrane in the event of excess pressure.

[0022] The at least one reinforcement cage can be connected to the reinforcement frame particularly efficiently if the reinforcement frame connected to the bursting membrane is configured to be connected to the cell housing on the outside, either directly or indirectly via the at least one reinforcement cage, using a thermal joining process. This allows a joining connection, such as a weld seam, to be introduced through areas of the reinforcement cage, which simultaneously also connects the reinforcement frame to the cell housing.

[0023] According to a further embodiment, the reinforcement frame has at least one edge slope and / or a flow separation edge. An edge slope can enable particularly optimal aerodynamics of a flow flowing out through an activated or ruptured bursting membrane. The use of a flow separation edge can be used to convert the flow resulting from overpressure from the battery cell from a laminar flow state to a turbulent flow state, thereby increasing the flow velocity and allowing the overpressure to be reduced more quickly.

[0024] According to a further aspect of the invention, a method for connecting a bursting membrane to a battery cell housing is provided. In one step, the bursting membrane is aligned relative to a reinforcing frame and integrally connected to the reinforcing frame. In a further step, the reinforcing frame connected to the bursting membrane is positioned on the inside of an interior volume of a cell housing at an opening in the cell housing. Subsequently, the reinforcing frame is integrally connected to the cell housing by applying a thermal joining process to an outer side of the cell housing in the region of the opening.

[0025] The method according to the invention ensures optimal tool access to the corresponding joints during the joining process. In particular, the method avoids the introduction of a weld seam from the inside of the cell housing, which would necessitate particularly small or narrow tools. The method enables the respective components to be joined by introducing joints on external surfaces, such as an outward-facing contour of the cell housing opening.

[0026] According to one embodiment, the reinforcement frame is firmly bonded to the cell housing by a thermal joining process configured as laser welding, soldering, contact welding, or thermally activated bonding. This allows the introduction of first joining connections and / or second joining connections to be implemented flexibly using different tools or joining processes.

[0027] The membrane arrangement can be introduced into the cell housing in a particularly simple manner from a technical perspective if the reinforcing frame connected to the bursting membrane is positioned on the inside in an internal volume of the cell housing with the aid of at least one positioning pin at an opening in the cell housing. In particular, the membrane arrangement can be inserted into the opening of the cell housing and optionally secured to the opening if the positioning pin is arranged adjacent to an edge contour of the opening in the cell housing. In this way, subsequent slipping of the membrane arrangement can be avoided if it is connected to the cell housing in a material-to-material manner. According to a further exemplary embodiment, the reinforcing frame is connected to the cell housing by introducing at least one weld seam in a region between the at least one positioning pin and the edge contour of the opening in the cell housing.This measure allows the area between the edge contour of the opening and the positioning pin to be reliably connected by creating a weld seam. With such a connection, the requirements for tool guidance accuracy are relatively low, making it particularly quick and technically simple to implement.

[0028] Several embodiments of the invention are explained in more detail below with reference to the drawings. They show:

[0029] Fig. 1 is a schematic sectional view of a membrane arrangement according to an embodiment of the invention,

[0030] Fig. 2 is a schematic sectional view of a bottom region of a cell housing of a battery cell with an inserted membrane arrangement from Fig. 1,

[0031] Fig. 3 is a schematic sectional view of a bottom region of a cell housing with a membrane arrangement according to a second embodiment of the invention,

[0032] Fig. 4 is a schematic sectional view of a bottom region of a cell housing with a membrane arrangement according to a third embodiment of the invention,

[0033] Fig. 5 is a schematic sectional view of a bottom region of a cell housing with a membrane arrangement according to a fourth embodiment of the invention, Fig. 6 is a schematic sectional view of a bottom region of a cell housing with a membrane arrangement according to a fifth embodiment of the invention, and

[0034] Fig. 7 is a schematic sectional view of a bottom region of a cell housing with a membrane arrangement according to a sixth embodiment of the invention.

[0035] In the illustrations, identical reference numerals identify the same elements or structural components. The sizes and relative positions of the elements in the illustrations are not necessarily drawn to scale, and some of these elements are enlarged and positioned for clarity. Furthermore, the specific shapes of the elements shown are not intended to convey information about the actual shape of the individual elements, but were selected merely for ease of identification in the illustrations.

[0036] The figures show various embodiments of membrane arrangements 10 in a battery cell 100. The battery cell 100 is already in an assembled or installed state and stands on a base area 31 or

[0037] Bottom region 31 of a cell housing 30 on a substrate. Gravity can, for example, act perpendicularly or perpendicular to the surface on the bottom region 31 of the cell housing 30.

[0038] Fig. 1 shows a schematic sectional view of a membrane arrangement 10 according to an embodiment of the invention. In the illustrated embodiment, the membrane arrangement 10 has a bursting membrane 11 and a reinforcing frame 12. The sectional view serves to illustrate an extension of the membrane arrangement 10 along a width direction B and a height direction H. The reinforcing frame 12 is integrally connected to the bursting membrane 11. For this purpose, a first joining connection 21 was introduced through the bursting membrane 11, which creates an integral joining connection between the reinforcing frame 12 and the bursting membrane 11. The arrows illustrate a direction of action by a tool (not shown), such as a laser welding tool. The first joining connection 21 can, for example, be designed as a circumferential weld seam.

[0039] The reinforcement frame 12 is designed as a circumferential frame and has a centrally arranged recess 13 so that the bursting membrane 11 can break or open into the recess 13 in the event of excessive stress due to excess pressure.

[0040] The reinforcement frame 12 connected to the bursting membrane 11 is designed to be inserted into a battery cell housing or cell housing 30 on the inside and to be connected to the cell housing 30 on the outside by a thermal joining process (see Fig. 2).

[0041] The reinforcement frame 12 has, for example, a positioning pin 14. The reinforcement frame 12, which is connected to the bursting membrane 11, can be aligned with an opening 33 of the cell housing 30 shown in Fig. 2 by means of the positioning pin 14. The positioning pin 14 protrudes into the opening 33 of the cell housing 30.

[0042] The positioning pin 14 is circumferentially or annularly shaped and surrounds the recess 13 of the reinforcing frame 12 on the circumference. The positioning pin 14 is shaped such that, when inserted into the opening 33 of the cell housing 30, it runs parallel to an edge contour of the opening 33 of the cell housing 30 or runs along this contour of the opening 33.

[0043] Fig. 2 shows a schematic sectional view of a bottom region 31 or bottom of a cell housing 30 of a battery cell 100 with an inserted membrane arrangement 10 from Fig. 1. For the sake of clarity, the other components of the battery cell 100, such as cell stacks, cell connectors, battery terminals, electrolyte, and the like, are not shown.

[0044] The membrane assembly 10 is arranged in the bottom region 31 such that the positioning pin 14, which is shaped as a positioning ring, protrudes into the opening 33 in a form-fitting manner. Preferably, the entire reinforcement frame 12 rests flat and flush on an inner side of the bottom region 31.

[0045] The opening 33 can have a round, oval, rectangular, or similar cross-section. The membrane assembly 10 reinforces the bottom region 31 of the cell housing 30. The membrane assembly 10 is connected to the bottom region 31 of the cell housing 30 by a circumferential second joining connection 22. The second joining connection 22 is configured, for example, as a weld seam.

[0046] The arrows in Fig. 2 illustrate the action of a joining tool, such as a laser welding tool, from an outside onto a circumferential gap between the positioning pin 14 and the contour of the opening 33 of the cell housing 30.

[0047] In the illustrated embodiment, the reinforcement frame 12 extends to the lateral walls 32 of the cell housing 30 and thus stiffens the cell housing 30 at the bottom. Figure 3 illustrates a schematic sectional view of a bottom region 31 of a cell housing 30 with a membrane assembly 10 according to a second embodiment of the invention. In contrast to the embodiment shown in Figure 2, the membrane assembly 10 here has additional structural stiffening in the form of a reinforcement cage 40. The reinforcement cage 40 can serve as a spacer for a flow cross-section.

[0048] The reinforcement cage 40 surrounds the bursting membrane 11 on the outside and allows free inflow to the bursting membrane 11 in the internal volume V of the cell housing 30.

[0049] In an alternative or additional embodiment, which is illustrated in Fig. 4, the membrane assembly 10 has a reinforcement cage 40, which is connected externally to the reinforcement frame 12. Thus, an area outside the internal volume V of the cell housing 30 is kept free by the reinforcement cage 40.

[0050] Furthermore, the reinforcement cage 40 enables additional reinforcement of the bursting membrane 11 and the reinforcement frame 12.

[0051] In Fig. 4, the reinforcement frame 12 connected to the bursting membrane 11 is further connected to the cell housing 30 on the outside directly via the reinforcement cage 40. This allows a second joining connection 22, such as a weld seam, to be introduced through regions or sections of the reinforcement cage 40, which simultaneously also connects the reinforcement frame 40 to the cell housing 30 in addition to the reinforcement frame 12.

[0052] Fig. 5 shows a schematic sectional view of a bottom region 31 of a cell housing 30 with a membrane arrangement 10 according to a fourth embodiment of the invention. In contrast to the figures already described, a sectional view is shown here to illustrate an extension of the membrane arrangement 10 along a longitudinal direction L. To enable particularly efficient reinforcement or stiffening of the bottom region 31, the reinforcement frame 12 protrudes on one side beyond the opening 33 and extends essentially over the entire bottom region 31 of the cell housing 30 along the extension of the cell housing 30 in the longitudinal direction L.

[0053] For the sake of clarity, no joining connections 21, 22 are shown in Fig. 5, Fig. 6 and Fig. 7.

[0054] Fig. 6 illustrates a schematic sectional view of a bottom region 31 of a cell housing 30 with a membrane arrangement 10 according to a fifth embodiment of the invention. In this embodiment, the reinforcement frame 12 has at least one edge-side bevel 41.

[0055] Such an edge slope 41 can improve the aerodynamics of a flow flowing out through a bursting membrane 11 activated or ruptured by overpressure. The flow can contain gaseous and liquid components of the electrolyte and is illustrated by the arrows.

[0056] According to a sixth embodiment, shown in Fig. 7, another membrane arrangement 10 with a reinforcement frame 12 is illustrated. The reinforcement frame 12 has a flow separation edge 42.

[0057] The flow separation edge 42 protrudes essentially perpendicular to the bottom region 31 and thus projects into the internal volume V of the cell housing 30. Depending on the design, a flow separation edge 42 can be arranged in the longitudinal direction L at the edge of the reinforcement frame 12 in order to force a flow separation with a resulting turbulent flow when a flow arises. The flow results, analogous to Fig. 6, due to an actuation or rupture of the bursting membrane 11 by exceeding a predefined pressure in the internal volume V of the cell housing 30. The flow thus consists of components that escape from the cell housing 30 and is illustrated by the arrows.

Claims

CLAIMS 1. Membrane arrangement (10), comprising a bursting membrane (11) and comprising 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 a cell housing (30) on the inside and to be connected to the cell housing (30) of a battery cell (100) on the outside by a thermal joining process.

2. Membrane arrangement 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 into a recess of the reinforcing frame (12) and is connected to the reinforcing frame (12).

3. Membrane arrangement according to claim 1 or 2, wherein the reinforcing frame (12) is designed as a circumferential reinforcing frame (12), wherein the reinforcing frame (12) is integrally connected to the bursting membrane (11) along an entire circumference.

4. Membrane arrangement according to one of claims 1 to 3, wherein the reinforcing frame (12) has at least one positioning pin (14), wherein the reinforcing frame (12) connected to the bursting membrane (11) can be aligned by means of the at least one positioning pin (14) at an opening (33) of the cell housing (30), wherein the at least one positioning pin (14) protrudes at least partially into the opening (33) of the cell housing (30).

5. Membrane arrangement according to claim 4, wherein the positioning pin (14) is designed as a circumferential positioning pin (14), wherein the circumferential positioning pin (14) is shaped such that it runs parallel to an edge-side contour of the opening (33) of the cell housing (30) when inserted into the opening (33).

6. Membrane arrangement according to one of claims 1 to 5, wherein at least one reinforcing cage (40) is arranged on the reinforcing frame (12).

7. Membrane arrangement according to claim 6, wherein the at least one reinforcement cage (40) is arranged on the inside of the cell housing (30) or outside of the cell housing (30) on the reinforcement frame (12).

8. Membrane arrangement according to claim 6 or 7, wherein the reinforcing frame (12) connected to the bursting membrane (11) is designed to be connected to the cell housing (30) on the outside directly or indirectly via the at least one reinforcing cage (40) by a thermal joining process.

9. Membrane arrangement according to one of claims 1 to 8, wherein the reinforcing frame (12) has at least one edge-side bevel (41) and / or a flow separation edge (42).

10. A method for connecting a bursting membrane (11) to a cell housing (30), in particular a cell housing (30) of a battery cell (100), wherein the bursting membrane (11) is aligned relative to a reinforcing frame (12) and is integrally connected to the reinforcing frame (12), the reinforcing frame (12) connected to the bursting membrane (11) is positioned on the inside in an internal volume (V) of the cell housing (30) at an opening (33) of the cell housing (30), and the reinforcing frame (12) is fixed to an outside of the cell housing (30) by applying a thermal joining process in the area of ​​the opening (33) is firmly connected to the cell housing (30).

11. The method according to claim 10, wherein the reinforcement frame (12) is integrally connected to the cell housing (30) by a thermal joining process designed as laser welding or as soldering or as contact welding or as thermally activatable bonding.

12. The method according to claim 10 or 11, wherein the reinforcing frame (12) connected to the bursting membrane (11) is positioned internally in an internal volume (V) of the cell housing (30) by means of at least one positioning pin (14) at an opening (33) of the cell housing (30), wherein the positioning pin (14) is adapted to an edge contour of the opening (33) of the cell housing (30) is arranged adjacent.

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 seam in a region between the at least one positioning pin (14) and the edge contour of the opening (33) of the cell housing (30).

14. Battery cell (100), comprising a cell housing (30) with at least one cell stack, which is arranged in an inner volume (V) of the cell housing (30) and comprising a membrane arrangement (10) according to one of claims 1 to 9, wherein the membrane arrangement (10) in a bottom region (31) of the cell housing (30) is arranged according to an assembled or installed state of the battery cell (100).

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