Cell of high-voltage battery and motor vehicle

Abstract

The invention relates to a cell (10) having a cell housing (12) which encloses a cell interior (20), the cell housing (12) having a first housing side (14) in which an openable cell vent opening (16) is arranged. The cell also has an electrode layer structure (22) arranged in the cell interior (20) and an insulating element (24) made of an electrically insulating material arranged in the cell interior (20) between the electrode layer structure (22) and the first housing side (14). In this case, the insulating element (24) has a rupture region (26), which directly faces the openable cell vent opening (16).

Description

Technical Field

[0001] The present invention relates to a battery cell having a cell housing that surrounds the cell interior, wherein the cell housing has a first housing side in which an openable cell exhaust opening is arranged. The battery cell also includes an electrode layer structure arranged in the cell interior and an insulation element made of an electrically insulating material arranged in the cell interior between the electrode layer structure and the first housing side. The present invention also relates to a motor vehicle. Background Art

[0002] If a battery cell experiences thermal runaway, particularly in high-voltage batteries for motor vehicles, very high pressures can build up inside the cell. To prevent uncontrolled cell rupture, such cells typically have an openable cell exhaust opening, such as a rupture membrane or pressure relief valve. This opening can also be referred to as a gas outlet, cell outlet, vent, or vent membrane. When a certain overpressure develops within the cell, the rupture membrane opens and / or ruptures, allowing hot gases and particles to escape from the cell through the subsequently opened rupture membrane. However, in thermal runaway cases of prismatic cells, it is often observed that even the cell cup (typically the cell housing) partially melts due to the hot gases. The cell cup is typically made of aluminum, which has a melting point in the range of 600 to 650 degrees Celsius. On the other hand, the exhaust gases (i.e., the gases escaping from the thermally runaway cell) reach a temperature of approximately 1200 to 1300 degrees Celsius, thus far exceeding the melting point of the cell cup. This makes it difficult to control the venting of the battery cells through the openable cell vent openings. The melting phenomenon begins, for example, at the edge of the vent in the cell cover and partially spreads deep into the sidewalls of the cell cup. However, using a high-temperature-resistant metal (such as stainless steel) to form the cell housing significantly increases the cost of such a battery cell.

[0003] US2018 / 0166676 A1 describes a battery cover structure comprising a cover, electrodes arranged on the cover, and an insulating element fixed below the cover. A vent valve is located in the center of the cover. A corresponding through-opening is arranged in the insulating element below the cover. Summary of the Invention

[0004] The object of the present invention is to provide a battery cell and a motor vehicle which, in the event of a thermal runaway of such a battery cell, can be opened to enable as limited a venting of the battery cell as possible through a releasable battery cell venting opening in a manner as cost-effective and efficient as possible, and at the same time prevent the melting of the battery cell housing as much as possible, or at least reduce or delay its melting as much as possible.

[0005] This object is achieved by a battery cell and a motor vehicle having the features according to the respective independent claims. Advantageous embodiments of the invention are the subject matter of the dependent claims, the description and the drawings.

[0006] The battery cell according to the present invention includes a cell housing that surrounds the cell interior, wherein the cell housing has a first housing side surface in which an openable cell vent opening is arranged; an electrode layer structure arranged in the cell interior; and an insulating element made of an electrically insulating material and arranged in the cell interior between the electrode layer structure and the first housing side surface. Furthermore, the insulating element has a rupture region that is directly opposite the openable cell vent opening.

[0007] The present invention is based on the following recognitions: a battery cell usually comprises an insulating element, for example made of plastic, in its cell interior, which is located between the electrode layer structure (for example an electrode roll with active material and / or an electrode stack with active material) and the cell container (i.e. generally the cell housing of such a battery cell). The main task of this insulating element is to ensure the electrical insulation properties within such a battery cell. Furthermore, the present invention is based on the recognition that the design and layout of such an insulating element influence the melting characteristics of the cell housing during cell venting. If such an insulating element is embodied as closed in the area directly opposite the openable cell venting opening, direct gas discharge through the insulating element and the openable cell venting opening cannot be achieved during venting. Therefore, the outflowing gas must bypass the insulating element, which leads to lateral melting of the cell housing. In contrast, designs of such insulating elements with permanent openings allow unimpeded airflow directly to the releasable cell venting openings of the cell separator elements during venting. However, this can also lead to melting of the cell housing starting from the edge region of the releasable cell venting opening due to the unimpeded airflow impinging on the edge region. Furthermore, permanent openings in the insulating element can impair the insulating function of the insulating element or reduce insulation safety during normal operation. The design according to the present invention, in which the region of the insulating element opposite the releasable cell venting opening comprises a rupture region that is substantially or completely closed during normal operation and is only simply ruptured during venting, allowing air to flow through the insulating element, ensures that insulation safety is not reduced during normal operation and that venting is facilitated in the event of thermal runaway. This allows for more effective prevention or at least reduction in degree or duration of lateral flow around the insulating element and the resulting melting of the cell housing. In particular, the rupture region allows gas to flow directly out of the cell through the releasable cell venting opening without the insulating element obstructing this direct outflow path. In addition, by means of the advantageous design of the rupture zone of the rupture element, which can also be referred to as an insulating element, an additional protection and / or shielding function is provided for the cell housing, in particular for the edge of the openable cell venting opening, during venting of the cell, as will be explained in detail later. In particular, in the event of a rupture of the rupture zone, for example, the rupture zone can be destroyed or torn in such a way that parts of the rupture zone are flipped up or folded up, thereby also being able to at least temporarily protect the edge of the openable cell venting opening from direct impact by the gas. It is therefore also possible to advantageously resist melting of the cell housing starting from the edge region of the openable cell venting opening during venting. Therefore, by means of this design of the insulating element, it is possible to advantageously facilitate the targeted venting of the cell through the openable cell venting opening in the event of thermal runaway, and in a particularly simple and efficient manner.

[0008] The battery cell can generally be designed, for example, as a prismatic cell, a pouch cell, or a round cell. The battery cell is preferably designed as a prismatic cell. In this case, the cell housing has a substantially cuboid geometry. In this case, the first cell housing side can be any of the six cell housing sides of this cuboid cell housing. The cell housing can include a housing cover and a cell container, the housing cover comprising the first cell housing side, and the cell container comprising the remaining five of these cell housing sides. The releasable cell vent opening and, in particular, the two cell poles (zell poles) of the cell can be arranged on the housing cover. The insulating element can be part of a cover assembly comprising the housing cover and, optionally, the cell poles. However, the cell housing can also have a different design or configuration. Preferably, the first housing side is a housing side that is not one of the two cell housing sides with the largest area. The releasable cell vent opening can, for example, be located on this first housing side between the two cell poles of the cell. The cell can, for example, be designed as a lithium-ion cell. The cell housing can be made of aluminum. This allows for a particularly weight-saving and cost-effective design. However, other materials can also be used.

[0009] An electrode layer structure can be understood in particular as an electrode stack or electrode coil. This electrode layer structure can include multiple electrode layers, such as an anode layer, a cathode layer, and at least one or more separator layers that separate the anode layer from the electrode layers. This layer structure can be wound, which then forms an electrode coil, or it can be stacked in multiple layers, which then forms an electrode stack. This electrode layer structure can be electrically connected to the corresponding poles of the battery cell via corresponding discharge elements. Furthermore, an electrolyte may be present within the battery cell.

[0010] The insulating element is arranged between this electrode layer structure and the first shell side. As a result, direct contact between the electrode layer structure and the first shell side can be avoided or prevented by the insulating element. The insulating element can be made of plastic, for example. In this case, it is very advantageous if the insulating element is made of a plastic that is as fireproof and / or flame-retardant as possible, in particular a plastic that meets V0 class. The insulating element can, for example, have an opening that is directly opposite the corresponding cell pole arranged on the first shell side in order to, for example, enable the electrode layer structure to come into contact with the corresponding cell pole. However, such contact can also be achieved in other ways. In this case, it is generally very advantageous and therefore preferred if the insulating element has as few permanent openings as possible and is, if possible, constructed as completely closed at least in the largest possible intermediate area adjacent to the rupture area.

[0011] The insulating element can, for example, be plate-shaped. In particular, it can be oriented substantially parallel to the first housing side surface. For example, the first housing side surface can have a first inner side surface facing the interior of the battery cell. The insulating element can extend over the entire or substantially the entire first inner side surface of the first housing side surface.

[0012] Furthermore, the cell may optionally also comprise one or more further insulating elements at other locations within the cell, but this is not essential within the scope of the present invention.

[0013] The openable cell vent opening can be designed as a rupture membrane or a pressure relief valve, for example. As mentioned at the beginning, the openable cell vent opening can also be referred to as a cell gas outlet or gas outlet opening, etc. For example, a passively opening and pressure-dependent opening rated breaking portion can be provided in the side surface of the first housing via the openable cell vent opening.

[0014] The rupture region of an insulating element can also be understood as a rated breaking portion. Here, the insulating element is designed in the rupture region so that in the event of thermal runaway of the battery cell or gas escape from the battery cell, the insulating element opens in this rupture region and, at the same time, is partially destroyed or ruptured, for example. For example, the rupture region can be implemented as a material weakening. Various design options for the rupture region will be explained in more detail below. Here, the rupture region is also preferably constructed as a single piece with other regions of the insulating element. Therefore, the rupture region is preferably not provided by a separate component. The rupture region and the rest of the insulating element can be made of the same material.

[0015] In another particularly advantageous embodiment of the present invention, the area of the rupture zone is smaller than the area of the openable cell vent opening, in particular, the rupture zone is completely within the projection area of the insulating element, which is generated by an imaginary vertical projection of the openable cell vent opening onto the insulating element. This vertical projection can, for example, be based on a first direction. For example, the rupture zone can be directly opposite the openable cell vent opening relative to the first direction. Therefore, the rupture zone is preferably smaller than the openable cell vent opening relative to a second direction and / or a third direction, each of which is perpendicular to the first direction and is defined as being perpendicular to each other. This has the significant advantage that, in the event of cell venting, a flow directly toward the edge region of the openable cell vent opening can be at least temporarily blocked by the insulating element, because the edge region of the insulating element surrounding the rupture zone, due to the rupture zone being designed to be smaller in the venting direction (which can correspond to the first direction mentioned above), covers the edge region of the openable cell vent opening. As a result, melting of the cell housing in the edge region of the openable cell vent opening can be more effectively prevented or at least delayed for a longer period of time.

[0016] According to another advantageous design of the present invention, the rupture region is designed as a localized material weakening. This weakening can be achieved, for example, by reducing the wall thickness of the insulating element. Consequently, the insulating element can have a thinner wall thickness in the rupture region than in other areas of the insulating element. During cell venting, the rupture region is the first region of the insulating element to be breached by the outflowing gas due to this weakening. This provides targeted gas guidance.

[0017] It can also be provided that the material weakening is provided by a reduced wall thickness of the insulation element throughout the entire rupture region. In other words, the entire rupture region can be designed with a reduced wall thickness compared to other regions of the insulation element. Within the rupture region, the insulation element can, for example, be designed with a constant wall thickness. This makes the design of the rupture region particularly simple.

[0018] According to another advantageous design of the present invention, the rupture zone is designed to have a material weakening that extends locally along at least one line and / or line structure (e.g., a line configuration) extending within the rupture zone. A boundary contour surrounding the rupture zone can also be understood as such a line. Therefore, the rupture zone can be designed so that it does not have an overall reduced wall thickness, but rather, for example, has a reduced wall thickness along one or more such defined lines or a line structure having multiple lines. In the event of a rupture, this advantageously enables targeted tearing or ripping of the rupture zone along the defined lines and / or lines of the line structure. This enables a more controlled and defined opening behavior of the rupture zone. For example, a boundary contour that encloses the rupture zone can be designed as such a rated breaking line, such as an incision line, or a groove or perforation line extending along the boundary line. For example, in the event of exhaust, this enables the rupture zone within the boundary contour to be completely torn off. Therefore, a material weakening can also be provided along a boundary contour that circumferentially surrounds the rupture zone, in particular, where the line structure completely or only partially surrounds the boundary contour. Alternatively, only the boundary contour can be designed as an incision. In the event of exhaust, the rupture region is then completely torn off from the remainder of the insulation element, for example.

[0019] According to another advantageous embodiment of the invention, the material weakening is designed as a continuously extending cut or a single or multiple interrupted cut, in particular along a line and / or line structure extending in the rupture area. For example, the cut can be understood as a groove taper or a material taper, which, however, does not completely penetrate the insulating element in this area. Therefore, the insulating element is closed in the area of the cut in the normal state. In the area of the cut, the insulating element has a reduced wall thickness. When pressure is applied, the insulating element is most likely to tear or open in the area of the cut. In order to enable the rupture area to tear or open along a defined line and / or line configuration, this line or the line of this line configuration or line structure can be designed with a continuously extending cut or groove, or with locally arranged cuts or groove sections spaced apart from each other, that is, they are at a certain distance relative to each other.

[0020] According to another advantageous embodiment of the present invention, the material weakening can also be designed as a continuously extending slot that completely penetrates the insulating element along at least one line and / or linear structure extending within the rupture region. In other words, the rupture region can also be configured as a slot that penetrates the insulating element. This facilitates opening the rupture region during degassing, while only a small opening in the insulating element exists through such a slot. According to another advantageous embodiment of the present invention, the material weakening can be designed as a perforated line formed by perforations and / or slots that completely penetrate the insulating element, particularly also along a line and / or linear structure. In other words, the rupture region can also be implemented as having one or more such perforated lines. This also allows for targeted opening along such defined lines, while minimizing the open area of the insulating element under normal circumstances.

[0021] In this case, the above-described embodiment variants of the material weakening can also be combined with one another in any desired manner within the same breaking region.

[0022] However, it is very advantageous if the insulation element has a material weakening in the rupture region which does not completely penetrate the insulation element, ie, for example, in the form of an above-mentioned cutout or groove, thereby maximizing the insulation protection effect of the insulation element in the normal state.

[0023] According to another advantageous embodiment of the present invention, the thread structure is designed such that the rupture zone includes at least one fold adjacent to the fold edge, wherein the contour of the fold edge and the fold edge is part of the thread structure, and in particular, the thread structure is designed such that the rupture zone is divided into a plurality of fold edges adjacent to the respective fold edge. Such fold edges or fold edges can be easily realized by the above-mentioned measures, namely by designing the threads of the thread structure as corresponding material weakenings, for example in the form of cuts, slits, perforations, etc. The fold edge can also be provided in a simple manner by grooves or cuts along the thread and / or other types of material weakenings in the form of the thread. This makes it easier to fold the fold edge around such a defined fold edge. Thus, a hinge or a hinge effect can be formed by the fold edge.

[0024] The remaining contour of this folded portion can also be designed as a corresponding material weakening, such as a groove, cutout, perforation, slit, etc. Thus, the contour portion of the folded portion that is to be torn apart during degassing (i.e., to be separated from the rest of the insulating element) can be arranged, for example, in an area of the rupture zone that is subject to higher gas pressure, such as an area more centrally located relative to the openable cell degassing opening. The folded edge can be positioned closer to the edge of the rupture zone or form such an edge or part of the boundary contour of the rupture zone. The contour line of the folded portion (along which the rupture zone is torn during degassing) can also be designed to have a greater material weakening than the folded edge. In other words, the folded edge can, for example, be implemented with a reduced wall thickness relative to the area of the insulating element outside the rupture zone, while the contour of the folded portion or the folded portion has a reduced wall thickness relative to the folded edge. For example, the folded edge can be designed as a groove whose depth is less than the depth of the groove along the folded portion or along the contour of the folded portion.

[0025] The embodiment of a rupture element with such a folded-over portion, i.e., a rupture zone, offers the additional significant advantage that the folded-over portion of the rupture zone can provide additional protection for the edge region of the releasable cell venting opening. By folding over the folded-over portion during venting, the folded-over portion of the rupture zone is positioned above the edge region of the releasable cell venting opening. This additionally protects the edge region from the outflowing hot gases, at least temporarily. Consequently, melting of the housing can be effectively prevented for a longer period of time. This protective effect, achieved by partially folding over the rupture zone, is particularly effective when the rupture zone is designed to be slightly smaller than the releasable cell venting opening.

[0026] Furthermore, it is advantageous if the material weakening (eg, a notch or a groove) providing the fold edge is located on the side of the insulating element facing away from the first housing side, thereby making it easier to fold open the folded portion.

[0027] According to another advantageous embodiment of the present invention, the fold edge is provided as part of the line structure by a boundary contour surrounding the rupture area in the circumferential direction, in particular wherein the line structure completely or only partially includes the boundary contour. In other words, the boundary contour surrounding the rupture area is particularly suitable as a fold edge. Here, the boundary contour can play the role of such a fold edge completely or only partially or partially. For example, the rupture area can be torn in its middle area, and the section generated in this process can be folded open accordingly around the boundary contour of the rupture area as a fold portion. Designing the boundary contour completely as such a fold edge or at least partially as such a fold edge or partially as such a fold edge makes it possible that the fold portion generated during rupture can be torn and folded up particularly advantageously.

[0028] According to another advantageous design solution of the present invention, the line structure includes a first line that extends linearly in a specific direction through most or the entire rupture area or extends almost completely through the rupture area, for example, at least 80% of the rupture area. Here, the direction can be, for example, the second direction or the third direction defined above. In addition, the rupture area is preferably geometrically adapted to the openable battery cell exhaust opening. The battery cell exhaust opening is, for example, designed to be elongated and / or elliptical and, for example, larger in size in the second direction than in the third direction. Therefore, it is also preferred that the rupture area is larger in size in the second direction than in the third direction. In this case, it is also very advantageous that the first line is, for example, a line extending in the second direction. The first line thus crosses the entire rupture area or almost the entire rupture area, for example, linearly, for example, in the second direction. Here, the first line is also preferably arranged as centrally as possible with respect to the third direction. The rupture area can be said to be divided in half by the first line. This advantageously achieves that the rupture area is torn along its center line during exhaust. The fold produced in this process is then preferably folded outwards around the fold edge extending along the circumferential contour or the boundary contour as described above and thus protects at least part, in particular a large part, of the edge region of the subsequently opened cell exhaust opening.

[0029] According to another advantageous design solution of the present invention, the line structure includes a second line and a third line, which are parallel to each other and intersect perpendicularly with the first line, and in particular almost or completely pass through the entire rupture area, especially in the third direction defined above. It can be said that this line structure can divide the rupture area into six sub-areas. When a rupture occurs, these six sub-areas correspond to six folding portions, and these six folding portions can be folded around the outer contour of the rupture area. This design is particularly advantageous when the rupture area is designed to be elliptical. This makes it simple to open the rupture area, especially in the rounded area. It can be said that this line structure can provide a double T profile. This can maximize the protective effect of the open battery cell exhaust opening in the event of exhaust.

[0030] Furthermore, the present invention relates to a battery for a motor vehicle, comprising a battery cell according to the present invention or one of its embodiments. The battery can be designed as a high-voltage battery, for example.

[0031] Furthermore, the present invention relates to a motor vehicle having a battery cell according to the present invention or one of its embodiments. In particular, the motor vehicle can include a battery according to the present invention or one of its embodiments.

[0032] The present invention also includes improvements of the battery according to the invention, which have the features already described in conjunction with the improvements of the battery cell according to the invention. Therefore, the corresponding improvements of the battery cell according to the invention will not be described again here.

[0033] The motor vehicle according to the invention is preferably designed as an automobile, in particular as a passenger car or truck, or as a bus or motorcycle.

[0034] The invention also includes combinations of features of the described embodiments. Thus, the invention also includes implementations each having a combination of features of a plurality of non-mutually exclusive described embodiments among the described embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The following describes an embodiment of the present invention.

[0036] Figure 1 is a schematic diagram of a battery cell according to an embodiment of the present invention;

[0037] Figure 2 is a schematic diagram of an insulating element of a battery cell according to an embodiment of the present invention;

[0038] Figure 3 is a schematic cross-sectional view of a battery cell in a normal operating state according to an embodiment of the present invention;

[0039] Figure 4 In the exhaust case according to an embodiment of the present invention Figure 3 Schematic diagram of the battery cell in;

[0040] Figure 5 is a schematic diagram of an insulating element of a battery cell according to another embodiment of the present invention;

[0041] Figure 6 is a schematic cross-sectional view of a battery cell in a normal operating state according to an embodiment of the present invention; and

[0042] Figure 7 In the exhaust case according to an embodiment of the present invention Figure 6 Schematic cross-sectional view of the battery cell in FIG.

[0043] The embodiments explained below are preferred embodiments of the present invention. In the embodiments, the components described in the embodiments are each individual, independently considered features of the present invention, which further improve the present invention independently of each other. Therefore, the present disclosure should also include feature combinations other than the feature combinations of the illustrated embodiments. In addition, the described embodiments may also be supplemented by other features of the present invention that have already been described.

[0044] In the figures, the same reference numerals respectively denote elements with the same function. DETAILED DESCRIPTION

[0045] Figure 1 A schematic diagram of a battery cell 10 according to an embodiment of the present invention, viewed from above, is shown. In this case, the battery cell 10 has a battery cell housing 12, which is made of a metal material, such as aluminum, for example. In this case, the housing 12 comprises a first housing side 14, on which an openable battery cell exhaust opening 16 is arranged, and in this example, the openable battery cell exhaust opening is constructed as a rupture element or rupture membrane 16 with an edge 16a as part of the housing 12. The battery cell 10 also comprises two battery cell poles 18, only one of which is visible in this illustration. In this example, both battery cell poles 18 are also arranged on the first housing side 14. The battery cell poles 18 are electrically conductively connected to the electrode layer structure 22 located in the battery cell interior 20 (see Figure 3 ).

[0046] Here, Figure 3 A schematic cross-sectional view of such a cell 10 is shown, for example, in normal operating state Z1, in which the openable cell vent opening 16 is closed. The electrode layer structure 22 contains active material. Furthermore, the electrolyte of the cell 10 can be present in the cell interior 20 . Furthermore, the cell 10 includes an insulating element 24 arranged between the electrode layer structure 22 and the first housing side 14 . The insulating element 24 is made of plastic, for example.

[0047] In the event of thermal runaway, depending on the design, conventional battery cells can face a design conflict between the insulating properties of the insulation elements, the freest possible outflow of exhaust gases, and the integrity of the cell container (i.e., the integrity of the cell housing). In extreme cases, the closed design of these insulation elements can lead to blockage of the gas outlets (i.e., the openable cell exhaust openings), which can cause erratic, sometimes expressive, exhaust behavior. The loss of cell container integrity caused by the melting process significantly reduces the controllability of heat propagation phenomena. In the area of the locally melted cell container, the insulating cell separators, which are usually located between adjacent cells, are then also eroded by the abrasive exhaust gases—i.e., by the outflowing gas flow and the abrasive particles contained therein—and gradually lose their insulating properties. This increases the likelihood of propagation to adjacent cells. Under these known conditions, a reliable and cost-effective fire safety design in the system has been extremely difficult to achieve.

[0048] The present invention or its design advantageously achieves in this case that the venting behavior of such a cell 10 is improved in a simple and efficient manner. This can be achieved in particular by a specific design of the insulating element 24. The insulating element advantageously has a rupture region 26, which is as follows Figure 2 shown.

[0049] Here, Figure 2 A schematic diagram of an insulating element 24 for a battery cell 10 according to an embodiment of the present invention is shown. The insulating element 24 is shown here as an example in a plan view from below, that is, from the battery cell interior 20 of the battery cell housing 12 . The insulating element 24 thus has a rupture region 26 that is directly opposite the releasable battery cell vent opening 16 relative to a specific direction, in this example, the z-direction shown. Furthermore, the x-direction shown may correspond to the second direction defined above, while the y-direction shown may correspond to the third direction defined above. Furthermore, the coordinate system shown may be a Cartesian coordinate system.

[0050] Furthermore, the dashed line 28 shown shows a projected area, which is obtained by the vertical projection of the openable cell exhaust opening 16 onto the insulating element 24 in the direction opposite to the z direction. The rupture area 26, which is bounded by the surrounding boundary line 26a, is preferably designed to be similar in geometry to the openable cell exhaust opening 16 and is also designed to be smaller, in particular both with respect to the shown x-direction and with respect to the shown y-direction. Therefore, the rupture area 26 is completely located within the projected area 28. This is very advantageous because it allows for the openable cell exhaust opening 16, in particular the edge area 16a provided by the cell housing 12 (see Figure 1) provides a special protective function. Because the portion 24' of the insulating element 24 that directly surrounds the rupture region 26 and is in contact with the rupture region 26 prevents gas from flowing directly to the edge region 16a during exhaust. In addition, the rupture region 26 is also designed so that it is completely or substantially completely closed (e.g., when the battery cell 10 is not in thermal runaway) in the normal operating state Z1. Figure 3 As shown), while in exhaust condition Z2 (as Figure 4 Schematically shown), a through-opening 30 is opened through the insulating element 24. For this purpose, the rupture region 26 can be at least partially destroyed and / or torn open and / or bent open, etc.

[0051] Here, Figure 3 A schematic cross-sectional view of a cell 10 is shown having an insulating element 24 with a rupture region 26 arranged directly below the cell exhaust opening 16 that can be opened. In this example, the rupture region 26 is designed so that it has a wall thickness d1 that is smaller than the wall thickness d2 of the insulating element 24 outside the rupture region 26. In this example, the rupture region 26 is particularly designed to have a constant wall thickness d1. The rupture region 26 is designed to have a very thin wall in this region, so that in the case of Figure 4 In the case of thermal runaway of the cell 10 shown, the rupture region can be easily broken through or penetrated by the outflowing air flow 32. Figure 3 and Figure 4 In the example shown, the rupture zone 26 can also be completely separated from the remaining insulation element 24 in the exhaust situation Z2. Figure 4 It can be seen that the at least temporarily intact part 24 ′ of the insulation element 24 protects the edge region 16 a of the cell degassing opening 16 which is subsequently opened in the degassing situation Z2 .

[0052] However, a different design is also possible for the rupture region 26. In particular, the rupture region does not necessarily have to be designed as a material weakening as a whole, but can, for example, also comprise a local material weakening extending along a line and / or a line structure.

[0053] Figure 5A schematic diagram of an insulation element 24 according to another embodiment of the present invention is shown. With the exception of the differences described below, the insulation element can be designed in the manner described above. In this example, the boundary outline 26a of the rupture region 26 is indicated by a dashed line, and the boundary of the projected area 28 is also indicated by a dashed line. In this case, it is also preferred that the rupture region 26 is smaller than the projected area 28. The rupture region 26 is not configured as a monolithic material weakening, but rather includes a line structure 30 that implements the material weakening of the rupture region 26. In other words, the material weakening of the rupture region 26 can be limited to the line structure 30. In this example, the line structure 30 includes a first line 32 that extends substantially straight in the second direction (i.e., the x-direction), particularly over a majority of the rupture region 26, and in particular over nearly the entire rupture region 26. Furthermore, the line structure 30 includes two second lines 34 that are spaced apart from each other in the x-direction, arranged parallel to each other, and particularly intersecting the first line 32 at right angles. These second lines 34 extend, for example, substantially straight in the y-direction, and in particular substantially straight in the y-direction over the entire width of the rupture region 26. Thus, the rupture region 26 can be subdivided into six regions 36a, 36b, namely two large regions 36a and four smaller regions 36b. In addition, a portion of the boundary contour 26a of the rupture region 26 (which can also be considered as part of the line structure 30 in particular) can be designed to have a material weakening, such as a groove or a cutout. At least the section of the boundary contour extending in the x-direction is designed to have such a material weakening and to provide a corresponding fold 38a. The material weakening design for providing such a fold 38a can be smaller than the material weakening design along the first line 32 and the second line 34. Thus, a hinge effect can be provided for the fold 36a by means of these folds 38a. Optionally, the boundary contour 26a in the region of the small fold 36b can also be constructed to have a corresponding material weakening for providing a corresponding fold 38b. This flip-open effect in the venting situation Z2 can provide additional protection for the edge region 16 a of the releasable cell venting opening 16 .

[0054] Figure 6 A schematic diagram of a cell 10 with an insulating element 24 is shown. Figure 5 Designed based on the description. Figure 6 In particular, the material weakening for providing the fold edge 38a and the material weakening for providing the predetermined breaking line 32 can be seen. Figure 6 In particular, the cell 10 is shown again in the normal operating state Z1, while Figure 7 The cell 10 is shown in the exhaust situation Z2. Figure 7The insulating element 24 with the outwardly turned fins 36a is correspondingly shown in the thermal runaway Z2. These fins protect the cell container 12 and the gas outlet 16 from the high temperature of the outflowing exhaust gas 32. Part of the rupture region 24, the folded portion 36a, is folded upward around the fold edge 38a and is simultaneously positioned protectively above the edge region 16a of the openable cell gas outlet opening 16—in particular, the cell gas outlet opening 16 that is thus opened in this case. This folding is indicated by the arrow 40. Thus, a hinge region is formed by the fold edges 38a, 38b. Furthermore, the cell 10 can be designed in the manner already described.

[0055] Furthermore, it is very advantageous if the insulating element 24 is generally designed with as few through-openings etc. as possible. Figure 2 and Figure 5 In the illustrated example, a central region B of the insulating element 24 is shown, which may extend over the entire width in the y-direction and, for example, over a substantial portion of the length of the insulating element 24 in the x-direction. A rupture zone 26 is provided in this central region B. The portion of the insulating element 24 surrounding the rupture zone 26 within this region B is preferably designed to be completely closed without any openings or perforations. Optionally, the rupture zone 26 may be designed with smaller openings, such as slots and / or perforations, to provide the aforementioned material weakening.

[0056] That is, a rated breaking portion in the form of a rupture region 26 can advantageously be arranged in the insulating element 24, which opens in the event of thermal runaway. In the insulating element 24, the rated breaking portion 26 can be geometrically smaller in scope or size than the projected opening 28 of the gas outlet 16. This prevents the hot exhaust gas 32 from flowing directly onto the metal 12 of the cell container and softening it. Consequently, the loss of integrity of the cell container due to the melting process can be effectively avoided or at least delayed. The rated breaking portion 26 in the insulating element 24 can be implemented by local thinning of the surface of the rupture region 24, or by a geometric cut along a specific rupture line and / or along the edge region 26a of the opening 30 to be created. During normal operation of the cell 10, as indicated by state Z1, the insulating element 24 performs the task of electrically insulating the interior of the cell without impairment. For example, a structure 30 can be introduced into the insulation element 24. This structure can be formed by the previously described wire structure 30 with material weakenings, and during thermal runaway, as indicated by state Z2, this structure opens and can be elastically bent by the outflowing exhaust gas 32, so that two fins 36a are positioned protectively in front of the metal edge 16a of the gas outlet 16. This creates a thermal insulation layer that protects the material of the cell container 12 and the gas outlet 16 from very high gas temperatures and significantly delays or, ideally, prevents melting processes in the cell container 12. This double-T geometry of the wire structure 30 can be designed as a slot and / or perforation, or as a taper, or generally as a predetermined breaking point in the insulation element 24.

[0057] Overall, these examples illustrate the potential of the present invention to provide an insulating element within a battery cell that has a protective function in the event of a thermal runaway of the battery cell. The design features described can largely resolve the conflicting objectives between electrical insulation, free venting, and the integrity of the cell container. This results in: improved venting behavior while maintaining the electrical safety of the prismatic cell; a defined and reproducible output / venting behavior; improved integrity of the cell container due to a delayed melting process; and a simpler and more cost-effective module and assembly design due to the elimination of expensive and very complex measures. For the design of the insulating element, the following features can be used in particular and, if necessary, combined: a closed design, in particular without openings or holes outside the gas outlet area, a predetermined breaking point in the gas outlet area of the prismatic cell, and a protective function of the thermally stable plastic of the insulating element.

Claims

1. A battery cell (10), comprising: - a cell housing (12), which surrounds the cell interior (20), wherein: The cell housing (12) has a first housing side surface (14), in which an openable cell exhaust opening (16) is arranged. - an electrode layer structure (22) arranged in the interior (20) of the cell, and an insulating element (24) made of an electrically insulating material, arranged in the interior (20) of the cell between the electrode layer structure (22) and the first housing side (14), It is characterized in that The insulating element (24) has a rupture region (26) which is directly opposite the releasable cell exhaust opening (16).

2. The battery cell (10) according to claim 1, characterized in that The area of the rupture region (26) is smaller than the area of the openable cell vent opening (16), in particular, the rupture region (26) is completely located within a projected area (28) of the insulating element (24), the projected area (28) being generated by an imaginary vertical projection of the openable cell vent opening (16) onto the insulating element (24).

3. The battery cell (10) according to one of the preceding claims, characterized in that The rupture region (26) is designed as a local material weakening, in particular wherein the material weakening is provided by a reduced wall thickness (d1) of the insulation element (24) in the entire rupture region (26).

4. The battery cell (10) according to one of the preceding claims, characterized in that The rupture region (26) is designed with a material weakening which extends locally in the rupture region (26) along at least one line (32, 34) and / or line structure (30) extending in the rupture region (26).

5. The battery cell (10) according to claim 4, characterized in that Material weakening - designed as a continuously extending incision or as a single or multiple interrupted incision; - a slot designed to extend continuously and completely penetrate the insulating element (24); - is designed as a perforated line having perforations which completely penetrate the insulating element (24).

6. The battery cell (10) according to any one of claims 4 or 5, characterized in that: The wire structure (30) is designed so that the rupture area (26) includes at least one folded portion (36a, 36b) adjacent to the fold edge (38a, 38b), wherein the fold edge (38a, 38b) and the contour of the folded portion (36a, 36b) are part of the wire structure (30), and in particular, the wire structure (30) is designed so that the rupture area (26) is divided into a plurality of folded portions (36a, 36b) adjacent to the corresponding fold edge (38a, 38b).

7. The battery cell (10) according to claim 6, characterized in that As part of the wire structure (30), the folds (38a, 38b) are provided by a boundary contour (26a) surrounding the rupture region (26) in the circumferential direction, in particular wherein the wire structure (30) completely or only partially includes the boundary contour (26a).

8. The battery cell (10) according to any one of claims 4 to 7, characterized in that: The line structure (30) includes a first line (32) that extends linearly in a specific direction through the entire rupture region (26) or at least a majority of the entire rupture region (26).

9. The battery cell (10) according to any one of claims 4 to 8, characterized in that: The thread structure (30) comprises a second thread and a third thread (34) which are parallel to each other and intersect the first thread (32) perpendicularly, and in particular extend through the entire rupture region (26).

10. A motor vehicle having a battery cell (10) according to any one of the preceding claims.

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