Battery module

Abstract

The invention relates to a battery module (1) with several individual battery cells (2) and cell connectors (3) which electrically connect a battery terminal (6) of one of the individual battery cells (2) to a battery terminal (7) of an adjacent individual battery cell (2), wherein each of the individual battery cells (2) comprises a venting area (5) weakened by a predetermined breaking point (4) in its cell housing, in which one of the battery terminals (6) is arranged. The battery module according to the invention is characterized in that at least one flow guide element (12) is provided, which surrounds the venting area (5) at least around a part of its circumference and which is configured to prevent or at least disperse venting gases from adjacent individual battery cells (2), wherein the cell connector (3) is guided through that part of the circumference to the battery terminal (6) arranged in the venting area (5) which is free of the flow guide element(s) (12).

Description

[0001] The invention relates to a battery module with a plurality of individual battery cells, with cell connectors which electrically connect a battery pole of one of the individual battery cells to a battery pole of an adjacent individual battery cell, according to the type defined in more detail in the preamble of claim 1.

[0002] Battery modules with a plurality of individual battery cells electrically connected via cell connectors are known from the prior art. For individual battery cells using lithium-ion technology, it is also common to provide a so-called venting opening. This can be a pressure relief valve or, in most cases, simply a predetermined breaking point in an area of ​​the cell casing of the individual battery cell. If excess pressure builds up inside the individual battery cell, this venting opening ruptures or opens any venting valve, allowing this excess pressure to be released. This releases hot gases, which often carry sparks, glowing particles, and the like.If these venting gases enter the area of ​​neighboring individual battery cells, they can heat them accordingly and cause these neighboring individual battery cells to react thermally, which could ultimately lead to a thermal chain reaction and the entire battery module "going thermally crazy." This is also referred to as thermal propagation.

[0003] This is particularly problematic when one of the battery terminals is located in the venting area. This is often, but not exclusively, the case with round cells. Due to the contact with a cell connector, which is typically led to the battery terminal from one side, when the venting area is torn open, it only partially opens in one direction, like a hinged lid. All of the gases accumulating within the cell casing then escape from this opening. They are therefore directed in a preferred direction with almost their entire volume flow, so that the individual battery cell adjacent in this direction is heated accordingly and thus endangered.

[0004] For this reason, DE 10 2013 213 877 A1 describes a battery system in which the battery housing is spatially divided into two areas by a gas-tight separating device. Each of the individual battery cells is arranged partially in the first area and partially in the second area, in such a way that the venting opening of the individual battery cell protrudes into the second area. Any gases released thus reach only the second area, which is sealed from the first area. This prevents the risk of a chain reaction; however, the battery housing is very complex, as it must be divided into two gas-tight, separate individual housings, and the passage points of the individual battery cells must be reliably sealed by the separating device.

[0005] The solution in WO 2023 / 003 260 A1 instead provides a type of separating frame that can shield the individual cells from each other in the area of ​​their venting openings. The separating frame contains notches through which the cell connectors, implemented here as a bus, are routed to the cell terminals.

[0006] US 2021 / 0 104 718 A1 describes a similar frame, which includes integrated cell connectors and is placed on the individual battery cells.

[0007] For further information on the state of the art, reference can also be made to US 2009 / 0 111 015 A1.

[0008] The present invention therefore has the object of providing an improved battery module according to the preamble of the main claim, in which the risk of thermal impairment of neighboring cells during the release of venting gases is minimized by simple and efficient means.

[0009] According to the invention, this object is achieved by a battery module having the features in claim 1, and here in particular in the characterizing part of claim 1.

[0010] Advantageous embodiments and further developments arise from the dependent claims.

[0011] The battery module according to the invention is to be constructed such that one of the battery poles is arranged in the venting region, which is weaker than the rest of the cell housing. According to the invention, at least one flow guide element is provided which surrounds the venting region around part of its circumference and which is designed to keep venting gases away from neighboring individual battery cells or at least disperse them, i.e. to distribute them over a larger volume area. This makes it possible to minimize the heat input into the neighboring individual battery cell lying in this direction. In the battery module according to the invention, the cell connector is now guided through that part of the circumference to the battery pole arranged in the venting region which is free of the flow guide elements.The flow guide elements are therefore preferably arranged in the area where the cell connector does not protrude into the venting area to contact the battery terminal. If venting occurs, the venting area will typically rupture toward the side facing away from the cell connector inlet. The venting gases thus flow in the direction of the flow guide elements, which disperse or deflect the venting gases to thermally protect the adjacent individual battery cells.

[0012] According to the invention, the cell connector comprises a first contact region for connecting to the battery pole in the venting region and a second contact region for connecting to the other battery pole of an adjacent individual battery cell. These two contact regions are connected to one another via a connecting web, wherein the first contact region is formed by the end of the connecting web and can, for example, simply be implemented as a rounded end of a trapezoidal or cuboid-shaped connecting web. Furthermore, it is provided that the second contact region is designed such that it partially encompasses the venting region of the individual battery cell to be contacted in the circumferential direction. The second contact region can therefore be designed, for example, to be C-shaped, semicircular, or the like in order to at least partially encompass the venting region.According to the invention, the at least one flow-guiding element is formed as part of this second contact region. The arrangement, in which this contact region at least partially encompasses the venting region circumferentially, allows the flow-guiding element also arranged in this region to be integrated with this second contact region. In the simplest case of the collar, the contact region can thus simply be designed with an upwardly curved end facing the venting region. Corresponding flow-guiding pins, rods, a grid, or the like could also be arranged here.

[0013] The at least one flow guide element can be arranged around more than half the circumference of the venting area. Such a section of, for example, two-thirds of the circumference is ideal for reliably diverting the venting gases from neighboring individual battery cells.

[0014] Another very advantageous embodiment can also provide for the at least one flow guide element to be configured approximately perpendicular to the surface of the venting area. This makes it possible to either reliably disperse the venting gases or, preferably, to deflect them perpendicularly from the venting area and thus perpendicularly from the individual battery cells of the battery module. The venting gases thus do not reach the critical area of ​​the adjacent individual battery cells, or at least not before they have cooled sufficiently.

[0015] A further very advantageous embodiment of the battery module according to the invention can provide for the at least one flow-guiding element to be formed as part of the cell housing and / or as part of a battery housing. The flow-guiding element can thus be applied entirely or partially to the cell housing or be integrally formed from the material of the cell housing. This flow-guiding element can interact with corresponding counter-elements of the battery housing or can also be formed exclusively by corresponding elements of the battery housing, which extend far enough into the area of ​​the cell housing to enable the desired effect.

[0016] As already mentioned above, the at least one flow guide element can be designed in the form of individual rods or a grid. The flow is then dispersed to accelerate its cooling and distribute the concentration of the gases, and thus the concentration of the thermal energy content of the gases, over a larger surface area.

[0017] Alternatively, according to a further very advantageous embodiment, the at least one flow guide element can be designed in the form of a collar. In contrast to the rods or grids, such a collar would be a continuous flow guide element made of a strip of material, which preferably extends upwards in the region of the cell casing, so that the escaping venting gases can flow laterally against it and thus divert them upwards.

[0018] According to a very advantageous development, this collar can be formed as part of the cell connector, forming a single piece with the cell connector. The integration of such a collar as a flow guide element into the cell connector is particularly simple and efficient. Integration into the cell connector, which is in principle possible not only for the collar but also for the rods or the grid, enables an extremely simple design that can also be used efficiently with conventional individual battery cells. Only a minor adaptation of the cell connector is required, which is much easier to implement and realize than a corresponding modification of the cell housings of the individual battery cells.

[0019] According to a very advantageous further development, the second contact area itself can be C-shaped, wherein the connecting web is arranged on the side opposite the opening of the C, so that from the connecting web the C can encompass the venting area accordingly.

[0020] The use of at least one flow-guiding element or, according to the particularly advantageous embodiment of a cell connector with an integrated flow-guiding element, can be used with any type of individual battery cell. The cells can therefore be prismatic individual battery cells, for example. However, the described construction is particularly advantageous when the individual battery cells are cylindrical, and this is provided according to a very advantageous embodiment of the battery module according to the invention. Such round cells can then have the venting region with the first battery pole centrally in one of the end faces, with the cell housing itself forming the second battery pole, so that the second contact region of the cell connector can be attached at any desired location on the cell housing.It is particularly advantageous if the cell connector is designed with a C-shaped section, which, for example, has a raised collar, and is arranged around the venting area of ​​one individual battery cell. The connecting web with the second contact area can then protrude through the remaining part of the circumference of the adjacent cell connector to the battery terminal of the adjacent individual battery cell located in the venting area.

[0021] Further advantageous embodiments of the battery module according to the invention also emerge from the exemplary embodiment which is described in more detail below with reference to the figures.

[0022] Showing: Fig. 1 shows an exemplary battery module in a prior art design; Fig. 2 the battery module according to Fig. 1 with open venting area of ​​the middle battery cell; Fig. 3 shows an embodiment of a battery module according to the invention; and Fig. 4 the design of the battery module according to Fig. 3 with open venting area of ​​the middle battery cell.

[0023] In the presentation of the Fig. 1 shows a battery module designated 1 in its entirety. The section of the battery module 1 shown here comprises seven individual battery cells, each designated 2. Some of these individual battery cells 2 are electrically connected to one another via cell connectors designated 3; here, three of the individual battery cells 2 are connected in series purely as an example. The cylindrical cell housings of the individual battery cells 2, which are designed as round cells, each have a predetermined breaking point 4 on their upper end face, which is only provided with a reference symbol on the individual battery cell 2 shown in the rear center, which is shown without a cell connector 3. Within this predetermined breaking point 4 there is a venting area designated 5, which ruptures in the event of excess pressure inside the individual battery cell 2 so that the gases causing the excess pressure can be released.One of the battery poles 6, typically the positive battery pole, is located centrally in this venting area 5. The outer annular section of the cell casing surrounding the venting area 5 forms the other battery pole 7, typically the negative battery pole.

[0024] The cell connectors 3 each comprise a first contact region 8, which is designed for electrical contact with the first battery terminal 6, and a second contact region 9, which is correspondingly designed for contact with the battery terminal 7. The second contact region 9 is essentially C-shaped and surrounds the venting region 5 by approximately two-thirds of its circumference. The first contact region 8 and the second contact region 9 are connected to one another via a connecting web designated 10, with one end of this connecting web 10 directly forming the contact region 8.

[0025] In the presentation of the Fig. 2, the same structure with the same designations is repeated. In contrast to the representation in Fig. 1, however, the venting area 5 of the middle single battery cell 2 is torn open, revealing a venting opening designated 11. Through the contact between the battery terminal 6 arranged in the venting area 5 and the first contact area 8 of the cell connector 3, the venting opening 11 is created essentially on the side of the venting area 5 facing away from the supply of the connecting web 10, i.e., essentially on the left side. Accordingly, all venting gases will exit from the venting opening 11 to the left or with a primary flow direction to the left. The single battery cell 2 shown in the center left, as well as the single battery cell 2 shown at the rear left and the single battery cell 2 shown in the center front, receive the majority of the venting gases and thus the thermal energy they contain.These individual battery cells 2 are therefore subjected to particularly high loads, creating an acute risk that a thermal event could also occur in these individual battery cells 2, causing their venting area to open and venting gases to escape. In the worst case, this could lead to a thermal chain reaction, the so-called "thermal runaway" of the battery module 1 or an HV battery constructed from such battery modules 1.

[0026] In order to prevent this with simple and efficient means, flow guide elements 12 are provided in the inventive design of the battery module 1. In the illustrations of the Fig. 3 and Fig. 4, this is shown by way of example using a particularly efficient embodiment. The structure of the battery module 1 corresponds to the illustration of Fig. 3 exactly the same as the Fig. 1, with the sole difference that flow guide elements 12 are provided in the form of a collar 12. In the following, the term "collar 12" will be used for the flow guide elements 12, since only one such element is shown in the embodiment chosen here. Of course, other forms, such as individual upright elements, a grid, or the like, would be conceivable.

[0027] The collar 12 is formed as part of the cell connector 3, and here in particular as part of the second contact area 9. It is realized as an upwardly folded area, which surrounds the venting area 5 by more than half of its circumference, so that only a part of the circumference remains free, through which the connecting web 10 of the adjacent cell connector 3 can protrude. If the venting opening 11 now tears open again, which is analogous to the illustration in Fig. 2 in the representation of the Fig.4 for the middle of the individual battery cells 2, the venting gases escaping from the venting opening 11 are redirected upwards, as is again shown here by the arrows. The venting gases are thus directed away from the adjacent individual battery cells 2 in order to efficiently prevent them from heating up due to the venting gases. The structure can be used with an upward outflow as shown here, as well as laterally or upside down, so that the venting gases can be diverted downwards and, for example, guided out of a battery housing surrounding the at least one battery module 1 via a known venting channel.

Claims

[1] Battery module (1) with a plurality of individual battery cells (2), with cell connectors (3) which electrically connect a battery pole (6) of one of the individual battery cells (2) to a battery pole (7) of an adjacent individual battery cell (2), wherein each of the individual battery cells (2) comprises in its cell housing a venting region (5) weakened by a predetermined breaking point (4), in which one of the battery poles (6) is arranged, wherein at least one flow guide element (12) is provided which surrounds the venting region (5) around at least part of its circumference and which is designed to prevent or at least disperse venting gases from adjacent individual battery cells (2), wherein the cell connector (3) is guided through that part of the circumference to the battery pole (6) arranged in the venting region (5) which is free of the flow guide element(s) (12),and wherein the cell connector (3) comprises a first contact area (8) for connecting to the battery pole (6) in the venting area (5) and a second contact area (9) for connecting to the other battery pole (7) of an adjacent single battery cell (2), , characterized by in that the contact regions (8, 9) are connected via a connecting web (10), wherein the first contact region (8) is formed by one end of the connecting web (10), and wherein the second contact region (9) is designed in such a way that it at least partially encompasses the venting region (5) of the individual battery cell to be contacted in the circumferential direction, and wherein the at least one flow guide element (12) is designed as part of the second contact region (9). [2] Battery module (1) according to claim 1, characterized by that the at least one flow guide element (12) surrounds the circumference of the venting area (5) by more than half. [3] Battery module (1) according to claim 1 or 2, characterized by that the at least one flow guide element (12) is formed approximately perpendicular to the surface of the venting area (5). [4] Battery module (1) according to one of claims 1 to 3, characterized by that the at least one flow guide element (12) is designed in the form of individual rods or in the form of a grid. [5] Battery module (1) according to one of claims 1 to 3, characterized by that the at least one flow guide element (12) is designed in the form of a collar. [6] Battery module (1) according to one of claims 1 to 5, characterized by that the at least one flow guiding element (12) is formed as part of the cell housing and / or part of the battery housing. [7] Battery module (1) according to one of claims 1 to 5, characterized by that the at least one flow guide element (12) is formed as part of the cell connector (3) in one piece therewith. [8] Battery module (1) according to one of claims 1 to 7, characterized by that the second contact area (9) is C-shaped. [9] Battery module (1) according to one of claims 1 to 8 characterized by the cylindrical design of the individual battery cells (2), the venting areas (5) of which are arranged with the first battery pole (6) centrally in one of the end faces, wherein the cell housing forms the second battery pole (7).

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