DE102019131229A1 - Battery module for a motor vehicle and motor vehicle - Google Patents

Abstract

The invention relates to a battery module for a motor vehicle in which simple battery cells (2) are retrofitted with a simple, metallic, thin housing wall (3) in order to counteract swelling of the battery cells (2). The battery cells (2) are retrofitted by inserting intermediate layers (4) into the spaces (6) that arise when the battery cells (2) are inserted into a housing (5) of a battery module. The intermediate layers are metallic structures which, in certain embodiments, have a relief structure (6). The intermediate layers (4) lie opposite one another and cause the battery cells (2) to be clamped in the housing (5) of the battery module, which counteracts swelling forces (8). The relief structures (6), which face one another with two opposing intermediate layers (4) with competing surface structures, enable a temperature control medium and / or the pressure compensation compound to be introduced. Furthermore, in certain embodiments they have a spring effect.

Description

The invention relates to a battery module for a motor vehicle and a motor vehicle with a battery module in which prismatic battery cells with a housing wall are arranged parallel to one another in the housing of the battery module, the housing walls of the battery cells being provided with spacers in the spaces between the individual battery cells in order to to subsequently strengthen the housing walls of the battery cells in order to prevent the battery cells from expanding during charging and discharging, known as swelling.

When building a battery module, one goal is to ensure the material rigidity and strength of the battery cells. During the charging and discharging process of a battery cell, e.g. a lithium ion battery, the battery cell expands, known as swelling. In order to extend the service life of the battery cell, swelling must be prevented.

In the pamphlet US 2013/0196215 A1 discloses a battery cell housing comprised of multiple layers of polymer and metal. The housing material is formed from an outer and an inner layer. The outer layer consists of a heat-resistant resin and a metal layer. The inner layer consists of a thermoplastic resin layer. In this construction, the material stiffness of the battery cell is brought about by the material composition. The material rigidity is brought about solely by the inherent material properties of the polymer layers. The subject of this publication therefore requires complexly manufactured battery housings which are expensive to manufacture.

In the pamphlet US 2013/0209868 A1 discloses a case wall of a lithium ion battery comprising a base material layer and sequentially coated adhesive layers having an aluminum layer, an anti-corrosion treated layer and a resin layer on one side of the base material layer. In this arrangement, the material properties of this multilayer structure in the interior of the battery cell ensure a rigidity of the housing wall of the battery cell, which prevents swelling. However, this rigidity does not lie in the structure of the individual materials, but in their intrinsic chemical composition and the respective material properties.

The invention is based on the object of counteracting swelling of a battery cell in a battery module in a motor vehicle as part of a retrofit solution for the battery cells that can be attached to the battery cell from the outside.

The object is achieved by the subjects of the independent claims. Advantageous developments of the invention are described by the dependent claims, the following description and the drawings.

The invention provides a battery module for a motor vehicle, in which inexpensive battery cells with housing walls that do not have a multilayer structure, with a housing wall reinforcement that is attached from the outside afterwards, can be used during installation in the battery module. The battery module comprises a plurality of prismatic battery cells, each of which is contained in a housing which has two housing walls arranged parallel to one another, each of which provides a housing wall surface of the housing on the outside, wherein a plurality of housings are arranged one behind the other in the battery module in such a way that in each case at least two outer housing wall surfaces face one another opposite. In other words, the housing wall surfaces of adjacent battery cells are parallel to one another. At least one intermediate layer made of steel or aluminum is arranged between two outer and opposing housing wall surfaces, the two outer housing wall surfaces resting against the at least one intermediate layer and being able to effect mechanical reinforcement. In other words: The attachment of the at least one intermediate layer in the respective intermediate space of the battery cells arranged in a housing causes a mechanical stiffening of the housing wall surfaces and thus hinders or reduces swelling of the battery cells during the charging and discharging process.

The invention has the advantage that the stiffening can be effected mechanically afterwards using metal materials and not in a multilayer structure inside a battery cell itself, so that any prefabricated battery cells can be used for the battery module. This multilayer structure can also be attached to a partial piece of the respective battery cell outside. Simple and less expensive battery cells with a housing made of a metallic material and a wall thickness of a few millimeters (approx. 0.3 to 0.8 mm) without an internal multilayer structure can be used. These battery cells can then be retrofitted with these intermediate layers.

So there is no need for a multi-layer structure in the area of the interior of the battery cell itself, where all other insulation components are also attached. The multilayer structure is attached outside of the battery cell. This outer multilayer structure can also be applied to a small partial piece of the battery cell. As a result of the multi-layer structure attached to a battery cell afterwards, inexpensive battery cells with thin housing walls can be used for the production of battery modules for motor vehicles. Many battery cells have a housing wall thickness of a few millimeters. In the present invention, housing walls with a wall thickness of approximately 0.3 to 0.5 mm can be used.

The invention also includes embodiments which result in additional advantages.

In one embodiment of the invention, a plurality of intermediate layers can be arranged between two adjacent battery cells and, by means of correspondingly designed relief structures, form spaces that can accommodate a heat conduction means or a pressure equalization means. Furthermore, a partial application of the intermediate layer to the housing wall can be made possible by the invention. In addition, correspondingly thin intermediate layers enable a spring effect and thus a higher crash tolerance where the corresponding surfaces of two oppositely arranged intermediate layers are in contact with one another.

In one embodiment, simple battery cells with metallic housing walls and without a multilayer structure are used. These battery cells are inserted into a clamping device, which can be the housing of a battery module, for example. In this clamping device, the battery cells lie parallel to one another with their housing wall surface. By previously applying an intermediate layer to one side of a housing wall of a battery cell, the gaps created by arranging the battery cell in the clamping device can be filled. In this case, the intermediate layer is applied as an additional layer to at least one partial surface of the housing wall of the battery cell in a material-proof manner, for example by means of an adhesive connection. If several of these battery cells, which are provided with an additional layer, are inserted into the housing of the battery module, the resulting cavities are filled. The resulting clamping in the housing prevents the battery cells from swelling due to the mutual pressing in the clamping device through the outer walls of the housing of the battery module. It is sufficient if one battery cell is provided with an additional layer on one side of one of the housing walls. This has the advantage that simple battery cells, which have a housing wall with a very small housing wall thickness of a few millimeters (approx. 0.3 to 0.8 mm), can be done afterwards by simply attaching the intermediate layer to the housing wall of a battery cell by means of a mechanical connection, can be reinforced. The mechanical connection can be made, for example, by gluing or welding. This results in a longer service life in the motor vehicle, since swelling can be hindered during normal operation of the battery module in the motor vehicle.

The applied intermediate layers can absorb the forces that arise during swelling, so-called swelling forces, which arise during operation of the battery cells in the housing of a battery module, since these are used as a whole in the clamping device. These forces are transferred to the intermediate layers and thus to the entire housing of the battery module. This creates a counterforce that prevents the battery cells from swelling in the battery module.

One embodiment provides that the intermediate layers are provided with a relief structure. If at least one additional layer with a relief structuring is applied to the respective opposite housing walls on a battery cell on two opposite sides of the housing and is inserted into a clamping device, for example the housing of a battery module, this results when correspondingly formed relief structuring of two intermediate layers are opposite one another , between the points at which the opposing intermediate layers touch, cavities. These cavities can be filled with a heat conduction agent or a pressure equalization agent. Not only are the swelling forces of the battery cells absorbed, but a heat conduction device or pressure equalization device is also made available. Sufficient mechanical stability is nevertheless ensured by the opposing, correspondingly designed relief structures. Furthermore, the correspondingly designed relief structures that rest against one another also produce a spring effect that can bring about a base pressure equalization. This has the advantage that the crash stability and thus also a deformation tolerance of the battery modules can be increased.

The invention also includes combinations of the features of the embodiments described so far. For example, intermediate layers can be applied to the housing wall of the battery cell that only partially encompass the housing wall surface, but also have relief structures, as described in the second embodiment.

The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger vehicle or truck, or as a passenger bus or motorcycle.

The exemplary embodiments of the invention are described below.

• 1 eine schematische Darstellung eines Längsschnitts einer Einspannvorrichtung eines Batteriemoduls, in der mehrere Batteriezellen angeordnet sind und dabei die Zwischenräume durch Zwischenlagen aufgefüllt werden;
• 2 eine Darstellung einer Gehäusewand der Batteriezelle, auf der ganz (Teil a) oder partiell (Teil b) eine Zwischenlage aufgebracht ist;
• 3 eine Darstellung einer möglichen Reliefstruktur auf einer Zwischenlage in 3D (Teil a) und 2D (Teil b); und
• 4 eine Seitenansicht von zwei gegenüberliegenden Zwischenlagen mit einer jeweils korrespondierend ausgelegten Reliefstruktur.

The invention also includes the combinations of the features of the described embodiments. This shows:

• 1 a schematic representation of a longitudinal section of a clamping device of a battery module, in which several battery cells are arranged and the spaces are filled by intermediate layers;
• 2 an illustration of a housing wall of the battery cell on which an intermediate layer is applied entirely (part a) or partially (part b);
• 3 a representation of a possible relief structure on an intermediate layer in 3D (part a) and 2D (part b); and
• 4th a side view of two opposing intermediate layers, each with a correspondingly designed relief structure.

The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention which are to be considered independently of one another and which also further develop the invention independently of one another. Therefore, the disclosure is also intended to include combinations of the features of the embodiments other than those illustrated. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

In the figures, the same reference symbols denote functionally identical elements.

1 shows a battery module 1 for a motor vehicle in a longitudinal section in which individual battery cells 2 are arranged. The case 5 of the battery module is, for example, a box made of a metal having a square shape. The box of the housing 5 has four boundary walls. When in the box of the housing 5 now one after the other prismatic battery cells are arranged and the box of the housing 5 with the battery cells 2 is completely filled, the battery cells are clamped 2 due to a front and a rear wall of the housing 5 facing each other causes. The case 5 thus functions as a jig for the battery cells 2 . When the case 5 now with battery cells 2 is filled, these can be positively arranged, parallel to one another. There can be gaps 7th arise when the housing 5 and the battery cells 2 do not fit together exactly in a form-fitting manner. The battery cells 2 are simple battery cells with a housing wall 3 made of a metallic material. The case wall 3 can have a very small wall thickness of a few millimeters, especially in the case of battery cells produced inexpensively with a metallic housing wall without a multilayer structure. The housing cannot withstand large mechanical forces, for example when the battery cell swells 2 when charging and discharging, can arise, absorb and thus counteract swelling. Now the spaces in between 7th between those in the housing 5 arranged battery cells 2 with intermediate layers 4th filled up. These liners 4th can also be made of the same material as the housing wall 3 or made of another metallic material. At least one intermediate layer can be used 4th or several intermediate layers 4th between two opposing battery cells 2 each in the space in between 7th inserted. If now the individual battery cells 2 Swelling occurs during operation, the resulting swelling forces 8th from the liners 4th on the walls of the case 5 , in which the battery cells are inserted. The case 5 the battery module takes in cooperation with the intermediate layers 4th and the battery cells 2 as a clamping device, the resulting swelling forces 8th and counteracts swelling.

2 shows a battery cell 2 with a housing wall 3 on which a liner 4th is upset. The liner 4th can be as large as part of the area of the housing wall 3 of the battery cells 2 . In various embodiments, the intermediate layer 4th on a partial part of the surface of the housing wall 3 can be applied by a solid connection. This can be an adhesive connection, for example. In other cases this liner can 4th by mechanical forces when the battery cells 2 for example in the housing 5 are arranged and the spaces 7th with the liners 4th be filled up by mechanical swelling forces 8th be held. If such battery cells are now in a clamping device, such as the housing 5 a battery module 1 , are clamped, the application of an intermediate layer is sufficient 4th which is only a partial area of the housing wall 3 includes. By having multiple battery cells 2 opposite can the swelling forces 8th be caught. It is thus sufficient if part of a surface of the housing wall 3 with a liner 4th is provided. It can be advantageous if the intermediate layer 4th if possible in a medium one Area of the surface of the housing wall 3 or on a particularly flexible area of the battery cell 2 is appropriate. If such battery cells 2 are now used in a jig, the resulting swelling forces 8th through the liners 4th to the adjacent battery cell 2 and at the end on the outer walls of the housing 5 transferred so that the housing 5 works as a jig.

This creates a counter-pressure to the swelling forces 8th , causing the swelling of the battery cells 2 can be contained.

3 shows an intermediate layer 4th in a profile view on which a relief structure 6th is appropriate. This relief structure 6th can, for example, be analogous to a relief structure of a corrugated sheet metal. Other advantageous relief structures are also possible 6th , the special mechanical effects or guiding function of media in the interstices 7th between adjacent spacers 4th with the same relief structure 6th arise, exhibit.

4th shows two opposing intermediate layers in a side view 4th each with corresponding relief structures 6th facing each other. The contour of the relief structure 6th causes cavities 9 arise and the intermediate layers 4th at certain points 10 , where the correspondingly formed relief structures 6th touch. The resulting cavities 9 can cause two effects: On the one hand, create a space that is available as space for heat conduction or pressure compensation means, or create a spring path for a mechanical spring effect. This pressure equalization is also important for externally acting forces, which arise, for example, in a crash, when the battery module is operated in a motor vehicle.

The battery cells should have a temperature that is as constant as possible during operation. It can make sense to heat them in winter, to cool them in summer or when driving. The heat either has to go to the battery cells 2 are supplied or discharged. In the second embodiment of the invention, in the cavities 9 Thermally conducting media, for example a temperature conducting means in the form of a heat conducting foil or of cooling material, can be inserted. These temperature control means can be carried out by the on the cavities 9 of the intermediate layers 4th be arranged. As the liners 4th consist of metallic material and thus usually have a very good thermal conductivity, the battery cells can 2 be cooled or heated.

Another possibility is to insert a pressure compensation medium in the cavities 9 . The medium can be a material that has a special spring effect, such as a deformation foam. Furthermore, it is possible that the corresponding relief structures formed 6th a spring effect is created, which can also exert a pressure equalization mechanically. This pressure equalization causes greater deformation stability and thus better crash stability. The housing of the battery cells 2 are simply formed in the exemplary embodiment without an inner multilayer structure and their housing walls cannot absorb large forces. They deform quickly and therefore initially have a low crash stability. The embodiment of the present invention with the correspondingly designed and opposing relief structures 6th of the intermediate layers 4th can use the same battery cells 2 to absorb and dissipate these forces from the outside that arise in a crash. This also increases the general safety of the battery module 1 in the motor vehicle.

The in 1 The exemplary embodiment shown may be based on the following situation as an example: The battery cells 2 in a prismatic shape with a simple, deep-cut housing wall 3 , which consists of a metal with a wall thickness of a few millimeters (approx. 0.3 to 0.8 mm), are arranged in series in a box-shaped housing. In retrospect, the battery cells 2 modified to prevent swelling and extend the life of the battery cells 2 to increase.

The in 4th shown embodiment with the intermediate layers 4th with correspondingly designed relief structures 6th also enables a heat conduction device to be set up. This also brings about a pressure equalization effect. Battery modules must be kept within a certain temperature range in motor vehicles. As the liners 4th consist of a metallic material, they have good to very good thermal conductivity. This enables a thermally conductive medium close to the battery cells 2 to bring and thereby better supply or dissipate heat. The intermediate layers function within the framework of crash safety and the absorption of external forces that can arise in a crash 4th also as a pressure compensation mass. The pressure equalization takes place either by a spring effect, which is caused by the in point 10 corresponding formed relief structures lying on top of one another 6th is effected, or by introducing a pressure compensation mass into the cavities 9 between two intermediate layers on top of each other 4th that at in the point 10 Corresponding relief structures lying on top of one another 6th arise.

The manufacturer of battery modules for a motor vehicle is enabled on the basis of the invention to use inexpensive, simple battery cells that are purchased externally and to install them in a high-quality battery module. In addition, a further embodiment of the invention provides a heat conduction means or a pressure compensation mass, which cause cooling and suspension of the individual battery modules. This is an important criterion for installation and also for safety in the motor vehicle.

The battery cells used can be prismatic battery cells, the cell bodies of which are, for example, simply drawn bowls with a lid, these being produced, for example, from an aluminum sheet by means of deep-drawing processes and the bowl forming a deep-drawn deep-drawn part. The cell bodies cannot contain a multilayer structure inside the cell body, but only consist of a sheet metal. The cell bodies can also be made from other metallic materials.

The additional layer can consist of any material, the additional layer preferably being made of the same material as the basic cell body of the battery cell. The additional layer can be mechanically firmly connected to the cell body of the battery cell and lie tightly on the cell body, for example with an adhesive or welded connection. The application of the additional layers wholly or only partially to the cell body causes a multilayer structure on the exterior of the cell body. The geometry of the additional layers can be designed such that the additional layers have a bead structure to generate rigidity. Furthermore, this bead structure can be designed in such a way that the additional layers can be plugged into one another, so that no installation space is lost between the cell bodies of the battery cells in a battery module.

Overall, the example shows how battery modules with, inexpensively produced battery cells, which have a housing made of a metal material with a wall thickness of a few millimeters (approx. 0.3 to 0.8 mm), are subsequently reinforced and thereby a Multi-layer battery cell structure is created when the battery cells are retrofitted from the outside. In this way, battery modules which are intended for use in a motor vehicle can have a longer service life.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the 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 assumes no liability for any errors or omissions.

Patent literature cited

• US 2013/0196215 A1 [0003]
• US 2013/0209868 A1 [0004]

Claims (10)

A battery module (1) for a motor vehicle, comprising a plurality of prismatic battery cells (2), each of which is surrounded by a housing which has two housing walls (3) arranged parallel to one another, each providing a housing wall surface (3) of the housing on the outside Battery module (1) several housings are arranged one behind the other in such a way that in each case at least two outer housing wall surfaces (3) lie opposite one another, characterized in that between two outer housing wall surfaces (3) arranged opposite one another at least one intermediate layer (3) made of steel or aluminum 4) is arranged, the two outer housing wall surfaces (3) resting against the at least one intermediate layer (4). Battery module Claim 1 wherein the housings are held together by a clamping device (5) with respect to a direction perpendicular to the housing wall surfaces (3). Battery module according to one of the preceding claims, wherein the at least one intermediate layer (4) has a predetermined relief structure (6). Battery module Claim 3 , a temperature control medium and / or a pressure compensation compound being arranged in a respective cavity (9) caused by the relief structure (6) between the at least one intermediate layer (4) and the housing wall surfaces (3) resting on the intermediate layer (4). Battery module Claim 4 , two adjacent intermediate layers (4) being provided and one of the intermediate layers (4) and a further intermediate layer (4) arranged adjacent to the one intermediate layer (4) having mutually corresponding relief structures (6) for receiving the temperature control agent and / or the pressure compensation compound . Battery module according to one of the preceding claims, wherein the at least one intermediate layer (4) only partially covers the housing wall surface (3) resting against it. Battery module according to one of the preceding claims, wherein the at least one intermediate layer (4) is materially and / or positively connected to at least one of the housing wall surfaces (3) resting against it. Battery module according to one of the preceding claims, wherein the at least one intermediate layer (4) is formed from the same material as a respective housing. Battery module according to one of the preceding claims, wherein in each housing the two housing walls (3) are each made of a sheet metal, in particular with a wall thickness of less than 1 millimeter. Motor vehicle with a battery module (1) for driving an electric drive machine of the motor vehicle, the battery module (1) according to one of the Claims 1 to 9 is trained.

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