DE102023100558A1 - High-voltage battery with a sealing element arranged in a degassing opening - Google Patents

Abstract

The invention relates to a high-voltage battery for an electrically or at least partially electrically driven vehicle, wherein the high-voltage battery has at least one battery cell (1), wherein the battery cell (1) has a cell housing with a safety valve (3) for degassing the battery cell (1), wherein the battery cell (3) is arranged in a housing enclosing the battery cell (1), wherein a housing wall (2) of the housing has a degassing opening (4) opposite the safety valve (3), wherein a sealing element (5) is arranged in the degassing opening (4), wherein the sealing element (5) has a through-channel (6) for discharging gases escaping from the safety valve (3) of the battery cell (1) from the housing, wherein the sealing element (5) has a shaft (8) circumferentially enclosing the through-channel and a flange (9) adjacent to the shaft (8), wherein the shaft (8) rests sealingly against the cell housing of the battery cell (1), wherein the shaft (8) Safety valve (3) of the battery cell (1) sealingly encloses, wherein the flange (9) engages behind the housing wall (2) on an outer side facing away from the battery cell (1), wherein the flange (9) is materially connected to the housing wall (2) and/or wherein an annular solid elastomer seal enclosing the degassing opening (4) is arranged between the flange (9) and the housing wall (2), which seals against the flange (9) and the housing wall (2).

Description

The invention relates to a high-voltage battery for an electrically or partially electrically powered vehicle, in particular for an electrically or partially electrically powered passenger car.

In electrically or partially electrically powered vehicles, numerous battery cells are connected together to form a high-voltage battery, also known as a traction battery. Such a high-voltage battery usually consists of several hundred, sometimes up to several thousand battery cells. The battery cells of the high-voltage battery are usually connected together to form battery modules, i.e. subgroups, whereby these battery modules typically have an identical number of battery cells. The battery cells are usually stacked in one stacking direction, thus forming a battery cell stack, also known as a cell stack, which is then inserted into a battery module housing.

Due to malfunctions, a battery cell can heat up considerably, causing the electrolyte of this battery cell to change into a gaseous state, which causes the pressure inside the battery cell to increase significantly within a short period of time. In order to prevent uncontrolled rupture of a cell casing or a shell of the affected battery cell, it is known to equip battery cells with a safety valve that opens at a predetermined internal cell pressure and allows the evaporated electrolyte and any other decomposition products that may have formed to escape. Such a process is also known as degassing. The safety valve can be formed by an opening in a cell casing that is closed with a rupture disk that bursts at a defined bursting pressure and thus releases the valve opening.

The gases released during degassing usually have high temperatures. The gases must be removed from the battery system or the high-voltage battery in such a way that passengers and sensitive components, such as other intact cells, are not damaged.

The battery cells are often arranged in a housing that encloses the battery cells, for example a battery module housing, to protect them against external influences and/or to directly cool the battery cells. In a design with a housing that encloses the battery cells, it is necessary to discharge the gases escaping from a safety valve of a battery cell from this housing in a controlled manner, in particular to avoid damage to the other battery cells arranged in the housing by the escaping hot gases. As a rule, such a housing has one or more venting openings for this purpose. The problem here is the permanent, secure connection of such a venting opening to the safety valve of the respective battery cell. On the one hand, there is the problem that battery cells, for example prismatic battery cells or pouch cells, are subject to a change in their thickness when charging and discharging, also known as breathing. In addition, age-related swelling can occur in battery cells. This means that the battery cells expand as they age. Such changes to the battery cells can result in the distance between the battery cell and the vent opening changing. Excessive mechanical impacts on the cell housing, such as those that could occur if the safety valves were rigidly connected to the vent opening, should also be avoided. In addition, contact between hot gas and the cooling medium should be avoided in the case of directly cooled battery cells.

The EN 10 2013 213 776 A1 In order to connect the cell valve to the degassing opening of the housing, the cell housing must have a connection piece surrounding a safety valve of the battery cell and the housing must have an opening corresponding to the connection piece, whereby a permanent mechanical connection is achieved by mechanically deforming the connection piece.

The object of the present invention is to provide a high-voltage battery which, with a simple design, ensures particularly safe discharge of the gases escaping from a battery cell during degassing.

This object is achieved by a high-voltage battery having the features of patent claim 1, and by a method having the features of patent claim 10. The high-voltage battery according to the invention is a high-voltage battery for an electrically or at least partially electrically driven vehicle, wherein the high-voltage battery has at least one battery cell, wherein the battery cell has a cell housing with a safety valve for degassing the battery cell, for protecting the battery cell from damaging overpressure, wherein the battery cell is arranged in a housing enclosing the battery cell, wherein a housing wall of the housing has a degassing opening opposite the safety valve, wherein a sealing element is arranged in the degassing opening, wherein the sealing element has a through-channel for discharging gases from the safety valve of the Battery cell escaping from the housing, wherein the sealing element has a shaft which circumferentially encloses the through-channel and a flange adjacent to the shaft, wherein the shaft rests sealingly on the cell housing of the battery cell, wherein the shaft seals around the safety valve of the battery cell, wherein the flange engages behind the housing wall on an outer side facing away from the battery cell, wherein the flange is materially connected to the housing wall, preferably welded or glued, and/or wherein an annular solid elastomer seal is arranged between the flange and the housing wall, which seals around the venting opening and rests sealingly on the flange and on the housing wall. Due to the circumferentially sealing contact of the shaft with the cell housing, the through-channel is sealed off from an interior of the housing enclosing the battery cell, so that a flow channel is formed which is sealed off from the interior of the housing for the hot gas escaping from the battery cell, more precisely the safety valve of the battery cell, through which the gas escaping from the safety valve is then discharged from the housing in a controlled manner.

The solution according to the invention offers particular advantages for directly cooled battery cells, i.e. high-voltage batteries in which a dielectric cooling medium, for example a cooling oil, flows directly around the battery cell, in particular a cell stack, and possibly other components such as contact rails and high-voltage connections in the housing. The sealing element according to the invention prevents or at least reduces mixing of the gas escaping in the event of degassing with the cooling medium. This prevents contact between the escaping gas and the cooling medium, which prevents the cooling medium from igniting on contact with the hot gas. In addition, the sealing element according to the invention prevents the safety valve from being subjected to internal pressure from the cooling medium, which has a beneficial effect on the service life of the battery cell.

The shaft does not necessarily have to be circular. It is entirely conceivable that the shaft has a rectangular cross-section or a rectangular cross-section with rounded corners.

In a particularly preferred embodiment, the shaft has a soft component at its end adjacent to the cell housing, in that it is a component that is softer than the section of the shaft adjacent to it. It is considered particularly advantageous if the shaft has an annular foam or elastomer seal at its end adjacent to the cell housing. Due to the deformability or compressibility of the annular foam or elastomer seal, the shaft end can conform particularly well to the shape of the cell housing around the safety valve and thus seal it off. In addition, a soft component or an annular foam or elastomer seal has the advantage that large tolerances in the axial direction, for example of up to several millimeters, can be compensated for by elastic deformation of the soft component, without this having a negative effect on the tightness of the shaft's connection to the cell housing. This can compensate for breathing and swelling of the battery cell.

It is considered particularly advantageous if the flange is firmly bonded to the housing wall, i.e. is glued axially to the housing wall. In this respect, it is considered particularly advantageous if an adhesive layer is applied to the underside of the flange facing the outside of the housing wall. The adhesive is preferably a PU adhesive, an epoxy resin adhesive or an acrylate adhesive.

It is considered particularly advantageous if the sealing element is designed like a sleeve.

In a particularly preferred embodiment, the sealing element works together to seal the housing enclosing the battery cell and seals off an interior of the housing that accommodates the battery cell from the outside. This seals off the interior of the housing from ambient air, dirt and moisture. In the case of a directly cooled battery cell in which a dielectric cooling medium, such as cooling oil, flows in the interior of the housing, the sealing element prevents leakage to the outside. In the case of a material-fit connection between the flange and the housing wall, the seal is preferably achieved by the material-fit connection between the flange and the housing wall. For example, an adhesive connection or welded connection that encloses the degassing opening can be provided.

In view of the need for good and simple sealing, an embodiment with an annular solid elastomer seal arranged between the flange and the housing wall, enclosing the degassing opening and sealingly abutting the flange and the housing wall, is considered to be advantageous.

It is considered particularly advantageous if the sealing element has a through-channel closing bursting membrane. This bursting membrane closes the passageway of the sealing element so that the safety valve is sealed against ambient air, dirt and moisture. The bursting membrane of the sealing element is designed in such a way that this bursting membrane bursts as soon as gas escapes from the safety valve of the corresponding battery cell and the pressure in the passageway increases as a result. For example, it is intended that the bursting membrane of the sealing element opens at internal pressures that are less than or equal to an internal pressure for opening the safety valve of the corresponding battery cell.

However, it is also quite conceivable that the sealing element as such does not have a bursting membrane closing the passage channel, but that a bursting membrane closing the passage channel is connected to the housing.

In a preferred embodiment, a plurality of battery cells are arranged in the housing, wherein the housing wall of the housing has a degassing opening opposite the respective safety valve of the battery cell, wherein a sealing element is arranged in each of the degassing openings.

Preferably, the battery cells are stacked in a stacking direction and in this way a battery cell stack, also called a cell stack, is formed, wherein the housing is formed by a battery module housing.

In a particularly preferred embodiment, the shaft has one or more locking elements, wherein the one or more locking elements engage behind the housing wall on an inner side facing the battery cell. In this respect, the sealing element comprises a clip-like locking mechanism on the housing on its inner side. These locking elements have the advantage that the locking elements form a positive connection with the housing wall, whereby the sealing element is mechanically supported on the housing wall via the locking elements. As a result, when the material-locking connection is provided, the material-locking connection in the area of the flange is relieved and the sealing element is prevented from coming loose. When the ring-shaped solid elastomer seal is provided between the flange and the housing wall, this also prevents the solid elastomer seal from no longer being sufficiently pressed against the housing wall and the flange, which can lead to leakage.

In a particularly preferred embodiment, it is provided that the one or more locking elements interact with the inside of the housing wall in such a way that the end of the shaft that is adjacent to the battery cell is pressed against the cell housing. This achieves a particularly high level of tightness in this contact area, so that volume changes of the corresponding battery cell during operation or over its lifetime and/or tolerances during production and assembly are compensated. Any deformation of the cell housing and/or the sealing element during degassing can also be compensated for in this way.

It is considered particularly advantageous if the one or more locking elements interact with the inside of the housing wall in such a way that the flange is pulled to the outside of the housing. This design ensures that, when a material-to-material connection is provided, the material-to-material connection, in particular in the form of an axial bond, between the flange and the outside of the housing is mechanically relieved of the contact pressure of the sealing element on the cell. This also enables safe and quick assembly of the sealing element since, for example, in the case of bonding, any necessary contact forces are applied by the locking elements until the bond hardens. It is then not necessary to apply such holding forces to the sealing element from the outside.

It is considered particularly advantageous if the housing is held in the area between the locking elements and the flange in the form of a press fit. This provides particularly good relief for the material connection between the flange and the outside of the housing and ensures that the solid elastomer seal is pressed on reliably.

In a preferred embodiment of the sealing element, the sealing element is a plastic part.

In a particularly preferred embodiment, the sealing element has a base body made of a first material and a sealing body made of a second material, the sealing body forming the part of the shaft that rests against the cell housing, the base body forming the rest of the shaft, in particular the locking elements, and the flange, the first material being stiffer than the second material. The sealing body is preferably molded onto the base body.

The material of the base body is preferably a temperature-resistant thermoplastic, such as polyamide (PA) or polyphthalamide (PPA) Polyetheretherketone (PEEK), or a thermosetting plastic, eg phenolic resin, which is reinforced with temperature-resistant fillers such as ceramic particles or aluminum oxide or glass fibers. The second material is preferably silicone or ethylene-propylene-diene rubber (EPDM) or a temperature-resistant foam.

It is considered particularly advantageous if the sealing element is manufactured using a two-component injection molding process, whereby a soft component of the injection molding forms the shaft end adjacent to the cell housing and a stiffer hard component of the injection molding forms the flange and the remaining shaft, in particular locking elements.

The battery cell(s) are in particular hardcase cells, such as prismatic cells or round cells.

Preferably, the cell housing of the battery cell has a thickness of 0.6 mm to 1 mm.

It is considered particularly advantageous if the housing wall of the enclosing housing has a thickness of 3 mm to 5 mm.

In a preferred embodiment, the housing is designed in the form of an extruded profile with one or more hollow chambers in which a plurality of battery cells are arranged, electrically connected and braced against swelling.

In a particularly preferred embodiment, the respective degassing opening in the housing is elongated, preferably at least twice as long in a first extension direction as in a second extension direction.

Preferably, the safety valve and the vent opening of the housing point downwards when the high-voltage battery is mounted in the vehicle.

It is considered particularly advantageous if the degassing opening of the housing is introduced by machining the housing by water jet cutting, laser beam cutting or milling or a combination of the aforementioned methods.

Preferably, the sealing element is inserted into the degassing opening from the outside of the housing.

Preferably, the housing wall 2 has a recess, wherein the flange is partially or completely received in this recess, so that the sealing element does not protrude or only slightly protrudes outwards relative to the rest of the housing wall adjacent to the recess.

In an advantageous method for producing the high-voltage battery according to the invention or one of the aforementioned advantageous embodiments of the high-voltage battery, it is provided that firstly the one or more battery cells, for example in the form of a cell stack, are inserted into the housing in an insertion direction such that the one or more degassing openings of the housing are aligned with the safety valve of the respective battery cell, wherein after the insertion of the one or more battery cells, a sealing element is inserted orthogonally to the insertion direction into the respective degassing opening and is materially connected to the housing, for example axially glued.

• 1 einen Teilbereich einer ersten Ausführungsform einer Hochvoltbatterie in einer Schnittansicht,
• 2 einen Teilbereich einer zweite Ausführungsform der Hochvoltbatterie in einer Schnittansicht.

In the following figures, the invention is explained in more detail using two exemplary embodiments, without being limited to these. They show:

• 1 a partial area of a first embodiment of a high-voltage battery in a sectional view,
• 2 a partial area of a second embodiment of the high-voltage battery in a sectional view.

The 1 shows a first embodiment of a high-voltage battery, with only a partial area of the high-voltage battery being shown. Only the area around an exemplary battery cell 1 is shown. The battery cell 1 is stacked together with a large number of other battery cells 1, which are not shown here for reasons of clarity, to form a cell stack, with this cell stack in turn being arranged in a battery module housing, with only one housing wall 2 of this battery module housing being shown. The respective battery cell 1 has a safety valve 3, often also referred to as a cell vent. This safety valve 3 is closed with a bursting membrane, with this bursting membrane opening when an internal pressure prevailing in the battery cell 1 exceeds a certain value. Accordingly, the safety valve 3 serves to degas the battery cell 1 to protect the battery cell 1 from damaging overpressure or uncontrolled rupture of a cell housing of the battery cell 1. The housing wall 2 of the battery module housing has a degassing opening 4 opposite the safety valve 3, wherein the degassing opening 4 or the housing wall 2 is spaced apart from the battery cell 1. In A sealing element 5 is inserted into the degassing opening 4 in such a way that the sealing element 5 passes through the degassing opening 4. The sealing element 5 as such has a through-channel 6 running in an axial direction Z for discharging gases escaping from the safety valve 3 of the battery cell 1 from the battery module housing. This through-channel 6 is closed in the present case by a bursting membrane 7 of the sealing element 5, wherein this bursting membrane 7 opens when the internal pressure prevailing in the through-channel 6 is lower than an internal pressure of the battery cell 1 at which the safety valve 3 of the battery cell 1 opens.

The sealing element 5 has an annular shaft 8 that circumferentially encloses the through-channel 6 and a flange 9 that adjoins the shaft 8 in the axial direction Z. The shaft 8 lies with its end facing away from the flange 9 in a sealing manner against the cell housing of the battery cell 1, with the shaft 8 circumferentially enclosing the safety valve 3 of the battery cell 1. This seals the through-channel 6 from the housing interior, in which a cooling oil flows in the present case. In order to achieve a good seal on the cell housing, the shaft 8 has an annular, deformable elastomer seal 10 on its end that adjoins the cell housing. The deformability of the elastomer seal 10 achieves a good seal and tolerance compensation. Due to the tight fit of the shaft 8 to the cell housing, the cooling oil flowing in the housing interior cannot reach the area of the safety valve 3 or the through-channel 6.

In order to hold the sealing element 5 securely in the housing wall 2, the flange 9 of the sealing element 5 protrudes radially outward from the shaft 8 and has a greater extension than the degassing opening 4. Accordingly, the flange 9 engages behind the housing wall 2 on an outer side facing away from the battery cell 1. The flange 9 is axially bonded to the housing wall 2 by an adhesive layer 11 applied to an underside of the flange 9 facing the housing wall 2. By bonding the flange 9 to the housing wall 2, the housing interior is sealed against ambient air, dirt and moisture. In an alternative embodiment, instead of or in addition to the adhesive layer 11, an annular solid elastomer seal can be arranged between the flange 9 and the housing wall 2, which seals against the flange 9 and the housing wall 2 and is pressed against the housing wall 2 via the flange 9 or is held clamped between the flange 9 and the housing wall 2. It is entirely conceivable that the flange and/or the housing wall has a groove for receiving the solid elastomer seal.

In order to ensure a particularly good and stable hold of the sealing element 5 in the housing wall 2 and to relieve the adhesive bond, the shaft 8 has several locking elements 12 that protrude radially outwards. These locking elements 12 are designed in such a way that they each have an inclined guide surface that tapers in the direction of the battery cell 1 in order to facilitate the insertion of the sealing element 5 into the opening 4 of the housing wall 2 by deforming the locking elements 12 radially inwards. As soon as the locking elements 12 reach their locking positions, which are in the 1 As shown, the locking elements 12 engage behind the housing wall 2 on an inner side of the housing wall 2 facing the battery cell 1. In this state, the sealing element 5 is virtually clipped to the housing wall 2 and is therefore additionally mechanically connected to the housing wall 2. The locking elements 12 are designed such that the locking elements 12 interact with the inner side of the housing wall 2 in such a way that the end of the shaft 8 resting on the battery cell 1, namely the elastomer seal 10, is pressed against the cell housing. In addition, the locking elements 12 are designed such that the locking elements 12 interact with the inner side of the housing wall 2 in such a way that the flange 9 is pulled to the outside of the housing wall 2. In this respect, the distance between the flange 9 and the locking elements 12 is selected such that a type of press fit is formed for the housing wall 2. The same applies to the distance between the locking elements 12 and the end of the shaft 8 or the end of the elastomer seal 10 and the distance between the battery cell 1 and the housing wall 2.

The sealing element 5 is in this case formed in one piece, wherein the sealing element 5 has a hard component and a soft component, wherein the hard component forms the flange 9, the bursting membrane 7 and a portion of the shaft 8 including the locking elements 12, and wherein the soft component of the sealing element 5 forms the shaft end adjacent to the cell housing of the battery cell 1, namely the elastomer seal 10. Such a sealing element 5 can be produced, for example, by a two-component injection molding process.

The 2 The second embodiment shown differs from that shown in the 1 illustrated first embodiment essentially in that the housing wall 2 has a recess 13, wherein the flange 9 is completely received in this recess 13, so that the sealing element 5 does not protrude outwards from the housing wall 2 adjacent to the recess 13. Furthermore, the 2 illustrated embodiment differs from that in the 1 illustrated embodiment in that the sealing element 5 as such does not have a bursting membrane, but a separate bursting membrane 14 is connected to an outer side of the housing wall 2 and closes the through-channel 6.

List of reference symbols

1

Battery cell

2

Housing wall

3

Safety valve

4

Degassing opening

5

Sealing element

6

Through channel

7

Bursting membrane

8th

shaft

9

flange

10

Elastomer seal

11

Adhesive layer

12

Locking element

13

Return

14

Bursting membrane

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• DE 102013213776 A1 [0006]

Claims (10)

High-voltage battery for an electrically or at least partially electrically powered vehicle, wherein the high-voltage battery has at least one battery cell (1), wherein the battery cell (1) has a cell housing with a safety valve (3) for degassing the battery cell (1), wherein the battery cell (3) is arranged in a housing enclosing the battery cell (1), wherein a housing wall (2) of the housing has a degassing opening (4) opposite the safety valve (3), wherein a sealing element (5) is arranged in the degassing opening (4), wherein the sealing element (5) has a through-channel (6) for discharging gases escaping from the safety valve (3) of the battery cell (1) from the housing, wherein the sealing element (5) has a shaft (8) circumferentially enclosing the through-channel and a flange (9) adjacent to the shaft (8), wherein the shaft (8) rests sealingly against the cell housing of the battery cell (1), wherein the shaft (8) seals the safety valve (3) the battery cell (1) in a sealing manner, wherein the flange (9) engages behind the housing wall (2) on an outer side facing away from the battery cell (1), wherein the flange (9) is materially bonded to the housing wall (2) and/or wherein an annular solid elastomer seal is arranged between the flange (9) and the housing wall (2) which encloses the degassing opening (4) and which bears sealingly against the flange (9) and against the housing wall (2). High-voltage battery according to Claim 1 , wherein the shaft (8) has a deformable annular foam or elastomer seal (10) at its end adjacent to the cell housing. High-voltage battery according to Claim 1 or 2 , wherein the sealing element (5) has a bursting membrane (7) closing the through-channel (6) or wherein a bursting membrane (14) closing the through-channel (6) is connected to the housing. High-voltage battery according to one of the Claims 1 until 3 , wherein a plurality of battery cells (1) are arranged in the housing, wherein the housing wall (2) of the housing has a degassing opening (4) opposite the respective safety valve (3) of the battery cell (1), wherein a sealing element (5) is arranged in each of the degassing openings (4). High-voltage battery according to one of the Claims 1 until 4 , wherein the shaft (8) has one or more locking elements (12), wherein the one or more locking elements (12) engage behind the housing wall (2) of the housing on an inner side facing the battery cell (1). High-voltage battery according to Claim 5 , wherein the one or more locking elements (12) interact with the inner side of the housing wall (2) in such a way that the end of the shaft (8) resting on the battery cell (1) is pressed against the cell housing. High-voltage battery according to one of the Claims 5 or 6 , wherein the one or more locking elements (12) interact with the inside of the housing wall (2) such that the flange (9) is pulled to the outside of the housing wall (2). High-voltage battery according to one of the Claims 1 until 7 , wherein the sealing element (5) has a base body made of a first material and a sealing body made of a second material, wherein the sealing body forms the portion of the shaft (8) adjacent to the cell housing, wherein the base body forms the remaining shaft (8) and the flange (9), wherein the first material is stiffer than the second material. High-voltage battery according to one of the Claims 1 until 8th , wherein an interior of the housing is traversed by a cooling medium. Method for producing a high-voltage battery according to one of the Claims 1 until 9 , wherein firstly the one or more battery cells (1) are pushed into the housing in an insertion direction such that the one or more degassing openings (4) of the housing are aligned with the safety valve (3) of the respective battery cell (1), wherein after the insertion of the one or more battery cells (1), a sealing element (5) is inserted orthogonally to the insertion direction into the respective degassing opening (4) and is materially connected to the housing.

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