Traction battery for a motor vehicle

Abstract

The invention relates to a traction battery (1) for a motor vehicle, comprising a battery housing in which several battery cells (2) and at least one cell separator (4) arranged between the battery cells (2) are provided. The cell separator (4) is provided to consist of a plurality of separate seeds (6).

Description

[0001] The invention relates to a traction battery for a motor vehicle, comprising a battery housing in which several battery cells and at least one cell separator element arranged between the battery cells are present.

[0002] For example, the prior art includes German patent application DE 10 2022 129 393 A1. This describes a cell separator element for thermally shielding two battery cells and for arrangement between the two battery cells of a battery, wherein the cell separator element comprises a gas-filled cushion having a length in a first direction, a width in a second direction and a thickness in a third direction, wherein the cushion has a first wall with a first closed circumferential edge region that limits the first wall in and opposite to the first direction and in and opposite to the second direction.

[0003] Furthermore, the cushion has a second wall opposite the first wall in the third direction, which has a closed and circumferential second edge region that limits the second wall in and against the first direction and in and against the second direction, with a gas-filled cavity formed between the first and second walls; wherein the first wall and the second wall are designed to be flexible such that the thickness of the cushion can be changed when the cushion is subjected to external force in the third direction. The first edge region is provided to be gas-tightly joined to the second edge region by a continuous joint.

[0004] Furthermore, German patent application DE 44 24 946 A1 discloses a foamed starch material, producible by: introducing a water-containing starch starting material with a content of one or more thermoplastic additives into an extruder; extruding the starch-containing material with foaming, wherein the product temperature immediately before the nozzle is 150 to 250 °C and the pressure is 30 to 70 bar, with expansion occurring when the material exits the extruder; and shaping the extruded foamed starch-containing material in a manner known per se.

[0005] Furthermore, the publication DE 20 2023 105 758 U1 describes an insulating material made from popped corn, in particular a non-flammable, waterproof, vapor-permeable material made from popped corn for the production of insulating panels. The insulating material is formed from a mixture containing 23 to 38 wt.% popped corn, 55.9 to 68 wt.% aqueous silicate solution, 2 to 6 wt.% aluminum hydroxide, 1 to 3 wt.% water, and 0.1 to 1 wt.% water glass stabilizer.

[0006] The object of the invention is to propose a traction battery for a motor vehicle which has advantages over known traction batteries, in particular ensuring a particularly reliable mechanical separation and thermal insulation of the battery cells from each other by means of the cell separating element.

[0007] According to the invention, this is achieved with a traction battery for a motor vehicle having the features of claim 1. It is provided that the cell separator element consists of a plurality of separate seeds, preferably seeds arranged loosely to one another, and in particular puffable seeds.

[0008] Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims. It should be noted that the exemplary embodiments described in the description are not limiting; rather, any variations of the features disclosed in the description, the claims, and the figures are possible.

[0009] The traction battery is preferably an integral part of the motor vehicle; however, it can, of course, also be separate from it, particularly until the traction battery is mounted on or in the motor vehicle. The traction battery is designed and configured for the intermediate storage of electrical energy for the motor vehicle's drive system. The drive system serves to propel the motor vehicle, thus providing drive torque for propelling the motor vehicle. To provide the drive torque, the drive system has at least one drive unit, which is designed as an electric traction motor electrically connected to the traction battery.

[0010] The traction battery comprises a battery cell assembly, which in turn contains several battery cells. The battery cells are preferably prismatic or pouch cells. The battery cell assembly forms, for example, a component of a cell module, which in turn can be part of a battery module. The battery module preferably includes end plates and / or a clamping device in addition to the battery cell assembly. The end plates are, for example, part of a battery module housing and accommodate the battery cell assembly between them. The battery cell assembly is positioned between the end plates and clamped by means of the clamping device to form the battery module. In this respect, the end plates are arranged on opposite sides of the battery cell assembly. Preferably, the battery module is cuboid or at least approximately cuboid.

[0011] The battery cells of the battery cell assembly are preferably electrically interconnected. For this purpose, the battery cells are arranged, for example, such that the electrical connections of the battery cells are located on the same side and / or facing each other. The connections are preferably electrically connected to each other by means of one or more busbars, which are also preferably electrically connected to electrical connections of the battery module and / or the traction battery. In other words, the battery cells of the battery module are electrically connected to the terminals via the busbars.

[0012] The traction battery has a battery housing containing a battery module receptacle designed and configured to hold one or more battery modules. During the manufacturing process, the battery module is inserted into this receptacle. Preferably, the battery housing does not contain just a single battery module, but rather multiple battery modules. In such a configuration, the battery housing has a corresponding battery module receptacle designed and configured to hold multiple battery modules.

[0013] The battery cells of a traction battery must be thermally and electrically insulated from one another to prevent a breakdown, particularly thermal breakdown, of adjacent battery cells in the event of thermal runaway in one cell. This is achieved using a cell separator. Known cell separators are made of materials such as aerogels, fleeces, or similar substances. However, these materials have the disadvantage of poorly absorbing forces acting between the battery cells; instead, they transmit these forces between the cells. Such forces can be caused, for example, by the expansion of the battery cells, which occurs over time within the traction battery. This expansion is also known as "swelling." Due to their inability to absorb the forces acting between the battery cells, the lifespan of the traction battery is reduced.

[0014] In some cases, a fluid-filled cushion is used as a cell separator. This is relatively well-suited to absorbing the forces acting between the battery cells. However, if these forces exceed a certain threshold, the cushion can be compressed. In this case, the battery cells are no longer separated by the cushion, which can lead to unwanted heat transfer between them through and despite the cushion.

[0015] For this reason, the cell separator element according to the invention is to be made of a more suitable material. Surprisingly, the applicant has found that the use of seeds as a component of the cell separator element is advantageous. The seeds are understood to be granular seeds of a plant. The seeds are thus a natural raw material that can be easily recycled. The seeds are used essentially unprocessed, in particular chemically and / or physically unchanged. At most, cleaning and / or sorting of the seeds by size is provided. However, apart from cleaning, the seeds are not thermally treated, at least not in such a way that a change in the volume of the seeds occurs.

[0016] In any case, the seeds are used separately; each seed therefore has at least a seed coat and an embryo enclosed within the seed coat. The seed coat remains unchanged in its shape; in particular, it is not opened or broken before the cell separator is placed in the battery housing. The seeds are loosely arranged relative to one another, allowing them to move freely. This enables the seeds to shift slightly as the battery cells expand, although this movement is limited by the available space. Therefore, unlike other cell separators, the described cell separator made from the seeds is not completely compressible. Alternatively, the seeds can be fixed relative to one another, for example, by means of a suitable support.

[0017] Puffable seeds are preferably used as seeds. Puffable seeds are seeds, specifically seeds or fruiting bodies of plants, which, due to their specific physical, chemical, and / or structural properties, significantly increase in volume under the influence of heat, pressure, and / or moisture. The increase in seed volume is primarily caused by the evaporation of moisture present within the seeds, thereby building up pressure that ultimately ruptures the seed coat.

[0018] Preferably, the seeds arranged in the battery housing initially have a completely closed seed coat, allowing the aforementioned pressure to build up within it, ultimately causing the seed coat to rupture. This rupture process is called puffing. Using the seeds, an active cell separator is achieved, which expands in volume when the battery cells' temperature increases, thereby pushing the battery cells apart. The seeds are preferably selected such that at a first temperature below a threshold value, they remain in their original state, particularly in an unpuffed state. At a second temperature above the threshold value, however, the seeds increase in volume, particularly through puffing, so that the seeds between the battery cells are in their unpuffed state.

[0019] Furthermore, the seeds are preferably selected such that in their puffed state they exhibit a stronger thermal insulation effect than in their unpuffed state, thus thermally decoupling the battery cells more effectively in the puffed state than in the unpuffed state. The cell separator element, composed of the seeds, is arranged between two of the battery cells. Preferably, such a cell separator element is located between each pair of battery cells, so that ultimately the seeds are arranged between all battery cells, spacing them apart and thermally separating them. Surprisingly, the seeds achieve a particularly effective result.

[0020] A further development of the invention provides that the seeds of the cell divider have grain sizes that differ from one another by at most 25%, at most 15%, or at most 10%. The seeds are thus selected based on their grain size; for example, an equivalent diameter of the seeds is used as the grain size. The grain sizes of the seeds that are part of the cell divider have at least similar values. Preferably, they differ from one another by at most 25%, at most 15%, or at most 10%, so that a fairly uniform distribution of the seeds in the cell divider can be achieved, particularly if they are loosely arranged.

[0021] A further development of the invention provides that a cavity located between the seeds is evacuated or filled with a fluid. In addition to the seeds, the cell separator includes the cavity, which is defined as the space within the cell separator not occupied by the seeds. For example, the cavity exists between seeds that are in contact at specific points, since these typically do not have a shape that allows for surface contact. This cavity is, for example, evacuated; that is, a negative pressure, in particular a partial vacuum, is created within the cavity.

[0022] Alternatively, the cavity can also be filled with the fluid, which in this context refers specifically to a gaseous fluid or a gas. For example, air or another suitable gas, such as nitrogen or a noble gas, is used. This further improves the effectiveness of the cell separator. The fluid can also be a binding agent that interacts with the seeds, particularly unpuffed seeds. For example, the binding agent is chosen such that at a temperature below the threshold, it allows the seeds to move relative to each other. However, if the temperature reaches or exceeds the threshold, the binding agent fixes the seeds relative to each other, thus holding them in a defined position between the battery cells.

[0023] A further development of the invention provides that the seeds are arranged in a casing and / or in a frame and / or attached to one or more supports. The casing is understood to be an element that completely encloses the seeds. The casing therefore has a closed interior space in which the seeds are arranged. The frame is an element that encompasses the seeds in only one direction; for example, the frame lies completely and continuously in an imaginary plane. It is possible for the casing and the frame to be combined.

[0024] The frame preferably forms a spacer that rests against the battery cells enclosing the cell separator on opposite sides, establishing a defined distance between them. The seeds are preferably arranged within the casing, which is enclosed by the frame. For example, in this case, the casing and the frame are manufactured as a single piece and / or from a single material. The aforementioned cavity is preferably enclosed by the casing, thus corresponding to the interior space already mentioned.

[0025] Additionally or alternatively, the seeds can be attached to the carrier(s), particularly by means of a material bond, for example, using a binding agent, especially an adhesive. For example, the carrier(s) are arranged within and / or attached to the frame. Additionally or alternatively, they can be located within the casing. With such a configuration, a defined structure of the seeds is achieved. Overall, the advantages described are reliably achieved with the described configuration of the cell separator element or the traction battery.

[0026] A further development of the invention provides that the casing consists of a fibrous material or a film and / or contains one or more of the following materials: plastic, metal, and ceramic. The casing can, in principle, be designed in any way desired; however, particularly good properties can be achieved with a casing made of the fibrous material or the film. The fibrous material consists of a plurality of fibers arranged in a defined fiber structure. For example, the fibrous material is fluid-permeable, particularly air-permeable. The film, on the other hand, is preferably fluid-impermeable, so that it encloses the seeds in a fluid-tight manner. The casing can consist of plastic, metal, or ceramic, or at least incorporate these materials. For example, a fibrous material or a film made of one of the aforementioned materials is used. This achieves the advantages already mentioned.

[0027] A further development of the invention provides that seeds are arranged on the carrier(s) either on one side or on both sides. In the former case, the seeds are arranged exclusively on one side of the carrier(s), while in the latter case, the seeds are located on the opposite side of the carrier(s) or are attached to the respective carrier(s) there. This also serves to achieve the advantages already described.

[0028] A further development of the invention provides that the cell separator is arranged in a space between the battery cells, which is closed by a cover attached to the battery cells. The space between the battery cells is created by spacing the battery cells apart from one another, for example, using the frame. It can be provided that the space is completely filled by the cell separator.

[0029] Especially if the space is not completely filled, it is advisable to seal the gap using the cover. The cover is attached to the battery cells and, together with the battery cells, completely seals the space, particularly creating a fluid-tight and airtight seal. The cover is preferably used with loosely arranged seeds, which are placed between the battery cells without a support and, in particular, without a casing and / or frame. The cover reliably holds the seeds between the battery cells.

[0030] A further development of the invention provides that a moisture reservoir is arranged in the cell separating element. The moisture reservoir is understood to be an element that holds moisture or a liquid and releases it to the seeds as needed. In particular, the moisture reservoir is designed such that it maintains a defined moisture level in the seeds or at least a defined moisture level in the interior of the coating or in the cavity.

[0031] For example, the moisture reservoir consists of a hygroscopic material that prevents the presence of liquid in the traction battery but releases moisture in the form of vapor or gas when needed. The moisture reservoir is preferably located within the casing and / or attached to the frame and / or the support. As already explained, sufficient moisture is often a prerequisite for seed puffing. This is reliably ensured by using the moisture reservoir.

[0032] A further development of the invention provides that the seeds are in the form of one of the following grains: cereal grains, in particular corn kernels, rice kernels, wheat kernels, spelt kernels, millet kernels and barley kernels; amaranth kernels and quinoa kernels. The aforementioned grains are each puffable, i.e., characterized by an increase in volume when a certain temperature is exceeded.

[0033] The grains mentioned can be divided into cereal grains and non-cereal grains. Cereal grains include corn kernels, rice kernels, wheat kernels, spelt kernels, millet kernels, and barley kernels. Amaranth kernels and quinoa kernels, however, do not originate from cereal plants and are therefore non-cereal grains. Of the grains mentioned, cereal grains, and of these, corn kernels, are particularly preferred, as trials conducted by the applicants have revealed especially positive properties.

[0034] A further development of the invention provides that the seeds are in an unpuffed state. This has already been mentioned. At least until the temperature of the battery cell exceeds the threshold, the seeds are therefore in a chemically and physically unchanged state, namely in an unpuffed state. However, if the temperature reaches or exceeds the threshold, the seeds puff, so that they are subsequently arranged at least partially, preferably completely, in an unpuffed state between the battery cells. This achieves the aforementioned advantages.

[0035] The features and combinations of features described in the description, in particular those described in the following figure description and / or shown in the figures, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention, in particular the scope of the claims. Thus, embodiments that are not explicitly shown or explained in the description and / or the figures, but which emerge from or can be derived from the explained embodiments, particularly within the scope of the claims, are also to be considered as encompassed by the invention.

[0036] The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing, without limiting the invention. The drawing shows: Fig. 1 a schematic sectional view through a traction battery, wherein in particular several battery cells and a cell separator arranged between them are shown in a first embodiment, and Fig. 2 a schematic representation of the cell separating element of the traction battery in a second embodiment.

[0037] The Fig. Figure 1 shows a schematic sectional view of a traction battery 1 for a motor vehicle. The traction battery 1 has a battery housing (not shown) in which several battery cells 2 are arranged. A cell separator 4 is arranged between the battery cells 2, i.e., in a space 3 between the battery cells 2. Additionally, the space 3 is sealed from the external environment, for example, by means of a fluid-tight cover 5. The cover 5 is preferably flexible and / or elastic, thus allowing relative movement of the battery cells 2 to at least a defined extent.

[0038] The cell divider 4 comprises a plurality of separate seeds 6, of which only a portion is shown here by way of example. The seeds 6 are arranged in a frame 7 of the cell divider 4, which completely encloses an interior space 8 of the cell divider 4 in one direction. Additionally, the seeds 6 are arranged in a casing 9, which, together with the frame 7, completely encloses the interior space 8. In the illustrated first embodiment of the cell divider 4, the seeds 6 are loosely arranged, i.e., movable relative to one another. The cell divider 4 also includes a moisture reservoir 10, in which moisture is stored and released into the interior space 8 as needed, so that the seeds 6 always have a defined moisture content.

[0039] The Fig.Figure 2 shows a schematic representation of a second embodiment of the cell separator element 4. This embodiment is fundamentally similar to the first embodiment, so reference is made to the corresponding descriptions, and only the differences are discussed below. These differences lie in the fact that the seeds 6 are no longer loosely arranged, but rather attached to a carrier 11. For example, the seeds 6 are bonded to the carrier 11, particularly using a binding agent, preferably an adhesive. The carrier 11 may be arranged in the interior 8 enclosed by the aforementioned casing 9. However, it may also be arranged that the seeds 6, together with the carrier 11, are located between the battery cells 2 without the use of the frame 7 and / or the casing 9.

[0040] In any case, the described cell separator element 4 ensures reliable mechanical and thermal separation of the battery cells 2. Furthermore, it is made of a renewable raw material that is easily recyclable. Accordingly, the traction battery 1 is designed to be more resource-efficient than previously available batteries. REFERENCE MARK LIST: 1 traction battery 2 battery cells 3 spaces 4 cell separator 5 Cover 6 seeds 7 frames 8 Interior 9 case 10 moisture reservoirs 11 carriers QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. 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

[0000] DE 10 2022 129 393 A1

[0002] DE 44 24 946 A1

[0004] DE 20 2023 105 758 U1

[0005]

Claims

Traction battery (1) for a motor vehicle, comprising a battery housing in which several battery cells (2) and at least one cell separating element (4) arranged between the battery cells (2) are present, characterized in that the cell separating element (4) consists of a plurality of separate seeds (6). Traction battery according to claim 1, characterized in that the seed grains (6) of the cell separating element (4) have grain sizes that differ from each other by at most 25%, at most 15% or at most 10%. Traction battery according to one of the preceding claims, characterized in that a cavity located between the seeds (6) is evacuated or filled with a fluid. Traction battery according to one of the preceding claims, characterized in that the seeds (6) are arranged in a casing (9) and / or in a frame (7) and / or are attached to one or more supports (11). Traction battery according to one of the preceding claims, characterized in that the casing (9) consists of a fiber material or a film and / or contains one or more of the following materials: plastic, metal and ceramic. Traction battery according to one of the preceding claims, characterized in that seeds (6) are arranged on the carrier (11) or carriers (11) only on one side or on both sides. Traction battery according to one of the preceding claims, characterized in that the cell separating element (4) is arranged in an intermediate space (3) between the battery cells (2), which is closed by a cover (5) attached to the battery cells (2). Traction battery according to one of the preceding claims, characterized in that a moisture storage element (10) is arranged in the cell separating element (4). Traction battery according to one of the preceding claims, characterized in that the seed grains (6) are in the form of one of the following grains: cereal grains, amaranth grains and quinoa grains. Traction battery according to one of the preceding claims, characterized in that the seeds (6) are in an unpuffed state.

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