Battery system and motor vehicle

Abstract

The invention relates to a battery system comprising a plurality of cells, each having a cell housing with a cell vent designed to open when a predetermined limit pressure is exceeded, and a substrate carrying the cells, the substrate having a number of vent openings corresponding to the number of cells, when viewed in the normal direction of the substrate, the exhaust openings completely penetrate the substrate, and the exhaust openings and the battery cells are arranged relative to each other such that the battery cell ventilation portion of each battery cell faces one of the exhaust openings. The invention is characterized in that a support plate is arranged between the base plate and the battery cell, the support plate has a recess which is arranged corresponding to the exhaust opening and extends into the exhaust opening in the normal direction, and the support plate is designed in the region of the recess to fail in the event that a predetermined boundary condition is exceeded, thereby releasing the exhaust opening.

Description

Technical Field

[0001] The invention relates to a battery system of the type specified in the preamble of claim 1 and to a motor vehicle according to claim 10 . Background Art

[0002] Battery systems for electric vehicles or high-voltage batteries for electric vehicles are sufficiently known in the prior art and comprise a plurality of individual cells, in particular lithium-ion cells.

[0003] A known challenge of such high-voltage batteries or battery systems for electric vehicles is that due to local overheating in a cell, for example due to a short circuit in the cell caused by an internal cell defect, thermal runaway of the cell may occur, which in turn may lead to overheating and short circuits, and thus to thermal runaway of adjacent cells. A chain reaction-like spread to adjacent cells, also known as thermal propagation, must be avoided because this can lead to a fire in the entire high-voltage battery or the entire battery system, thereby posing a considerable safety risk to the occupants of the electric vehicle.

[0004] In order to prevent the battery cell from catching fire and / or exploding in the event of thermal runaway, it is known to provide a predetermined breaking point in the battery housing of the battery cell. This breaking point is designed to break when a predetermined limit pressure in the interior of the cell housing is exceeded, and to allow a gas and / or flame jet to escape from the interior of the cell housing, see DE 10 2020102 221 A1. The breaking point (hereinafter also referred to as cell vent) can be designed in various ways, for example in the form of a rupture membrane, more precisely similar to a door arranged on one hinge or a salon door arranged on two hinges.

[0005] A battery system of this type is disclosed in DE 10 2009 046 385 A1, according to which the battery cells each have a ventilation opening and are arranged on a base plate in such a way that the ventilation opening is aligned with a corresponding channel formed in the base plate. Summary of the Invention

[0006] The object of the present invention is to improve a battery system of the type specified in the preamble of claim 1 such that in the event of a thermal runaway of a cell of the battery system, a spread to adjacent cells, ie, heat propagation, is prevented.

[0007] This object is achieved by the features stated in the characterizing part of claim 1 in combination with the features of its preamble.

[0008] Dependent claims 2 to 9 present advantageous developments of the battery system according to the invention.

[0009] The battery system according to the invention comprises, as is known per se, a plurality of battery cells and a base plate carrying the battery cells. The battery cells each have a cell housing with a cell vent designed to open when a predetermined limit pressure is exceeded, while the base plate has a number of exhaust openings corresponding to the number of battery cells and, therefore, the number of cell vents, the exhaust openings completely penetrating the base plate, as viewed in a normal direction N of the base plate. The exhaust openings and the battery cells are arranged relative to one another such that the cell vent of each battery cell is aligned with and opposite one exhaust opening.

[0010] The term "battery cell" should not be construed as limiting the battery cell to a specific design. That is, the battery cell installed in the battery system may be designed as a round battery cell, a prismatic battery cell, or a pouch battery cell.

[0011] Furthermore, it should be noted, supplementally only, that the normal direction N should not be understood as limiting the battery system's installation configuration in the vehicle. That is, with reference to a vehicle-mounted coordinate system whose x-axis extends along the vehicle's longitudinal axis and points in the direction of travel (=forward), whose y-axis extends along the vehicle's transverse axis and points accordingly to the left, and whose z-axis is oriented upward along the vehicle's vertical axis, the battery system according to the present invention can be arranged such that the normal direction N points in the x-, y-, or z-direction of the vehicle-mounted coordinate system.

[0012] The battery system according to the invention is characterized in that a support plate is arranged between the base plate and the battery cells, the support plate having a recess arranged corresponding to the exhaust opening and extending into the exhaust opening in a normal direction N, wherein the support plate is designed in the region of the recess to fail when predetermined boundary conditions are exceeded, thereby releasing the exhaust opening.

[0013] Here, the predetermined boundary conditions are understood to be in particular temperature and / or pressure. That is, when a predetermined temperature is exceeded and / or a predetermined pressure is exceeded, the support plate fails in a targeted manner in the region of the recess and thus releases the exhaust opening.

[0014] The support plate provided according to the present invention has proven particularly advantageous because, in the event of thermal runaway of a cell, it acts as a protective shield for adjacent cells and thus successfully prevents a chain reaction from spreading to adjacent cells of the battery system. The recess provided according to the present invention has the effect of providing a receiving space for material displaced from the cell housing when the cell vent opens in the event of thermal runaway of a cell, thereby reducing the risk of blockages forming in front of the cell vent. A further advantage of the recess is that it also forms a compensation volume for the hot gas flow that is primarily displaced in the first phase of thermal runaway, thereby ensuring an immediate pressure reduction in the cell housing of the cell experiencing thermal runaway, which has the effect of reducing the risk of the cell housing of the cell experiencing thermal runaway opening outside the cell vent. Furthermore, it is advantageous to ensure that sensitive cell vent areas of the cell housing are not affected by assembly forces during assembly.

[0015] Preferably, the depressions in the support plate each have at least one local material weakness, which is dimensioned such that it fails, i.e., melts and / or breaks, when predetermined boundary conditions exist, in particular when a predetermined temperature and / or a predetermined pressure are exceeded. This embodiment has the advantage that the corresponding material weakness can be realized simply and therefore cost-effectively.

[0016] Another embodiment provides that the recess of the support plate has at least one predetermined breaking line, which is designed to fail under predetermined boundary conditions. Failure along the predetermined breaking line has the effect of enabling a large-scale breakage of the recess. The predetermined breaking line can be designed, for example, in the form of a perforation.

[0017] Preferably, the support plate is formed from plastic, in particular reinforced plastic. However, it is also conceivable to form the support plate from metal or composite materials.

[0018] Another embodiment is characterized in that the recess comprises a protective material on its side facing away from the exhaust opening. The applied protective material has the effect of thereby ensuring improved resistance to reflections / rebounds of gases / particles from below, thereby improving the intended protective shielding function for adjacent cells in the event of thermal runaway.

[0019] In order to ensure that the cell vent can be opened mechanically cleanly in the event of thermal runaway, a particularly preferred embodiment provides that the recess of the support plate is correspondingly designed in the form of a groove and has a bottom surface that maintains a clear distance from the associated cell vent, and the size of the recess is designed in such a way that the clear distance is greater than the maximum extension dimension of the cell housing section that can be broken out of the cell housing when the cell vent is opened.

[0020] The clearance required for a clean, mechanical opening depends, among other things, on the specific design of the cell ventilation, which, as already mentioned, can be designed, for example, in the form of a rupture membrane, similar to a door on one hinge or a salon door on two hinges, etc. However, preliminary tests have shown that the clearance should be between 4 and 6 mm.

[0021] To ensure targeted discharge of harmful gases escaping in the event of thermal runaway, the base plate has an exhaust duct on its side facing away from the support plate, into which the exhaust openings open. Particularly preferred is an arrangement in which the battery system is configured such that the normal direction N is oriented in the z-direction of a coordinate system fixed to the vehicle. In other words, when viewed in the z-direction, which is the vertical direction of the vehicle, the exhaust duct is arranged below the base plate. This advantageously ensures that exhaust in the event of thermal runaway is directed downward, thus away from the occupants.

[0022] In order to ensure sufficient protection against moisture during normal driving operation, the exhaust duct is preferably designed to be closed in cross section.

[0023] In order to enable sufficient cooling of the battery system, another embodiment provides that the base plate has at least one cooling hole oriented orthogonally to the normal direction N, through which a coolant can flow.

[0024] Another preferred embodiment is characterized in that the ventilation openings are provided with a first sealing element and / or a second sealing element arranged on the support plate, wherein, viewed in the longitudinal direction L of the ventilation openings arranged in a row, the first sealing element is assigned to an edge region of the ventilation openings oriented perpendicularly to the longitudinal direction L, and the second sealing element is assigned to an edge region of the ventilation openings oriented in the longitudinal direction L. The advantage of this design is that the sealing elements hinder the undesired escape of venting, i.e., "lateral gasses," which can still diffuse beneath the battery cells even before and / or after the recesses have been deliberately deactivated or opened, and the venting of venting into high-voltage spaces, which are typically used for the electrical connection of the battery cells, is hindered. Another advantage is that the sealing elements ensure a neat support / contact of the battery cells on the support plate.

[0025] The present invention is also based on the object of improving a motor vehicle, in particular an electric vehicle, comprising a battery system such that, in the event of a thermal runaway of a cell of the battery system, further damage to the vehicle is prevented as far as possible.

[0026] This object is achieved by a battery system according to any one of claims 1 to 9 .

[0027] All embodiments of the battery system according to the invention are transferable analogously to the motor vehicle according to the invention, so that the advantages described above can also be achieved with this motor vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Further advantages and possible applications of the invention will emerge from the following description in conjunction with the exemplary embodiments shown in the drawings.

[0029] In the attached figure:

[0030] Figure 1 shows a cross-sectional view of a first embodiment of a battery system according to the present invention;

[0031] Figure 2 A second embodiment of the battery system according to the invention is shown in a cutaway illustration; and

[0032] Figure 3 A sectional illustration of a battery system according to the invention is shown according to a third embodiment. DETAILED DESCRIPTION

[0033] In the following description and drawings, to avoid repetitions, identical components and parts are denoted by the same reference numerals, unless a further distinction is necessary or meaningful.

[0034] Figures 1 to 3 The battery system is shown in an exploded view and is generally designated by reference numeral 10. The battery system 10 mainly includes a plurality of battery cells 12 and a substrate 14 that supports the battery cells 12. The normal direction of the substrate 14 is designated by reference numeral N.

[0035] The base plate 14 of the battery system 10 has a number of exhaust openings 16 corresponding to the number of battery cells 12. When viewed in the normal direction N, the exhaust openings completely penetrate the base plate 14 and lead into an exhaust channel 18 that is closed in cross section. Figures 1 to 3 As shown, the exhaust openings 16 are arranged in a row, and the longitudinal (arrangement) direction L of the exhaust openings arranged in a row is indicated by reference symbol L.

[0036] The battery cells 12 each have a cell housing 12a having a cell vent 12b that is designed to open when a predetermined limit pressure is present, thereby enabling venting of the battery cells 12. The battery cells 12 and the vent openings 16 are arranged relative to one another such that the cell vent 12b of each battery cell 12 is aligned with and positioned opposite the vent opening 16.

[0037] Still Figures 1 to 3As shown, the battery system 10 according to the present invention further includes a support plate 20 arranged between the base plate 14 and the battery cells 12. A particular feature of the support plate 20 is that the support plate has a recess 22 arranged corresponding to the exhaust opening 16 and extending into the interior of the exhaust opening 16 when viewed in the normal direction N.

[0038] In this example, if Figures 1 to 3 As shown, the exhaust opening 16 is designed in the form of an elongated hole, and the depression 22 accordingly has a groove shape that follows the elongated hole-shaped contour of the exhaust opening 16 .

[0039] The support plate 20 is designed in such a way that, if predetermined boundary conditions are exceeded, in particular if a predetermined temperature and / or a predetermined pressure is exceeded, the support plate 20 fails in a targeted manner in the region of the depression 22 and thus releases the exhaust opening 16 .

[0040] In the present exemplary embodiment, the depression 22 has a corresponding material weakness for this purpose, which is dimensioned such that in the event of thermal runaway, the material weakness melts away in a targeted manner due to the resulting hot particle flow, thus resulting in a targeted failure.

[0041] The function of the support plate 22 is to serve as a protective shield for adjacent cells 12 in the event of thermal runaway of a cell 12 , thereby successfully preventing chain reaction-like spread to adjacent cells 12 of the battery system 10 and thus successfully preventing heat propagation.

[0042] Another advantage is that the recess 22 ensures that, in the event of thermal runaway of the cell 12 , space is provided for the material expelled from the cell housing 12 a when the cell vent 12 b is opened, thereby reducing the risk of blockage in front of the cell vent 12 b.

[0043] Another advantage is that the recess 22 also forms a compensating volume for the hot air flow discharged mainly in the first stage of thermal runaway, thereby ensuring that the pressure is immediately reduced in the cell housing 12a of the thermally runaway cell 12, which has the effect of reducing the risk of the cell housing 12a of the thermally runaway cell 12 opening at a position other than the cell ventilation portion 12b.

[0044] exist Figure 2 The second embodiment shown in FIG. 1 essentially corresponds to the embodiment shown in FIG. Figure 1 The embodiment shown in .

[0045] exist Figure 2The embodiment shown in FIG is particularly characterized by the fact that, viewed in the longitudinal direction L, the longitudinal sides of the venting openings 16 in the form of elongated holes are provided with first sealing elements 24 arranged on the support plate 20. The sealing elements 24 arranged between the battery cells 12 provide an improved sealing effect, thereby preventing undesired venting or the escape of "cross-gassing" in the event of thermal runaway. This is to say, gases that could diffuse beneath the thermally runaway battery cell 12 even before the recesses 22 have been deliberately broken or opened. A further advantage is that the sealing elements 24 have a tolerance compensation effect, thereby also ensuring, in particular, improved support and contact of the battery cells 12 on the support plate 10.

[0046] exist Figure 3 The second embodiment shown in FIG. 1 essentially corresponds to the embodiment shown in FIG. Figure 2 The embodiment shown in .

[0047] exist Figure 3 The embodiment shown in FIG is characterized in that a protective material 26 is applied to each side of the recess 22 facing away from the exhaust opening 16. The protective material 26 ensures that the back side of the recess 22 has a higher resistance to gas / particle reflection, so that in the event of a thermal runaway of the battery cell 12, the desired shielding function for adjacent battery cells 12 is improved.

Claims

1. A battery system (10), comprising a plurality of battery cells (12) and a substrate (14) supporting the battery cells (12), wherein: Each of the battery cells (12) has a battery cell housing (12a), the battery cell housing having a battery cell vent (12b), the battery cell vent being designed to open when a predetermined limit pressure is exceeded, wherein the number of exhaust openings (16) provided by the base plate (14) corresponds to the number of the battery cells (12), and the exhaust openings completely penetrate the base plate (14) when viewed in a normal direction (N) of the base plate (14), wherein the exhaust openings (16) and the battery cells (12) are arranged relative to each other such that the battery cell vent (12b) of each battery cell (12) is opposite to one exhaust opening (16), It is characterized in that A support plate (20) is arranged between the substrate (14) and the battery cell (12), and the support plate has a recess (22) arranged corresponding to the exhaust opening (16) and extending into the exhaust opening (14) along the normal direction (N), wherein the support plate (20) is designed to fail in the area of the recess (22) when a predetermined boundary condition is exceeded, thereby releasing the exhaust opening (14).

2. The battery system (10) according to claim 1, characterized in that The recesses (22) of the support plate (20) each have at least one local material weakness that is dimensioned to fail in the presence of predetermined boundary conditions.

3. The battery system (10) according to claim 1 or 2, characterized in that The recess (22) of the support plate (20) has at least one predetermined breaking line, which is designed to fail when predetermined boundary conditions exist.

4. The battery system (10) according to claim 1, characterized in that The recess (22) has a protective material (26) on its side facing away from the exhaust opening (16).

5. The battery system (10) according to claim 1, characterized in that The recess (22) of the support plate (20) is designed to be groove-shaped and has a bottom surface that maintains a clear distance from the associated battery cell ventilation portion (12b). When viewed in the normal direction (N), the size of the recess (22) is designed so that the clear distance is greater than the maximum extension size of the battery cell housing section that can be broken out of the battery cell housing (12a) when the battery cell ventilation portion (12b) is opened.

6. The battery system (10) according to claim 1, characterized in that The base plate (12) has an exhaust duct (18) on its side facing away from the support plate (20), into which the exhaust opening (16) opens.

7. The battery system (10) according to claim 6, characterized in that The exhaust duct (18) is designed to be closed in cross section.

8. The battery system (10) according to claim 1, characterized in that The base plate (12) has at least one cooling hole perpendicular to the normal direction (N) and through which a cooling medium can flow.

9. The battery system (10) according to claim 1, characterized in that The exhaust openings (16) are provided with a first sealing element (24) and / or a second sealing element arranged on a support plate (20), wherein, viewed along the longitudinal direction (L) of the exhaust openings (16) arranged in a row, the first sealing element (24) is assigned to an edge region of the exhaust openings (16) oriented perpendicular to the longitudinal direction (L), and the second sealing element is assigned to an edge region of the exhaust openings (16) oriented along the longitudinal direction (L).

10. A motor vehicle comprising a battery system (10), characterized in that The battery system (10) is a battery system according to any one of claims 1 to 9.

Images