Battery module

Abstract

The invention relates to a battery module (1) with several individual battery cells (3, 5) between which intermediate plates (2, 4, 6, 14) are arranged. The battery module according to the invention is characterized in that the individual battery cells (3, 5) are designed as cylindrical cells, wherein the intermediate plates (2, 4, 6, 14) have indentations extending transversely to a longitudinal direction (L), in which at least one of the individual battery cells (3, 5) is arranged with a portion of its circumference, and the intermediate plates (2, 4, 6, 14) are connected along their end edges parallel to the longitudinal direction (L) to a cover plate (15), wherein the connections are designed as welded joints, in particular as laser welds (9, 13, 16).

Description

[0001] The invention relates to a battery module with several individual battery cells, between which intermediate sheets are arranged.

[0002] Batteries with one or more battery modules, especially high-voltage batteries as defined by ECE R100, are known from the prior art. They are frequently used in vehicles with at least partial electric drive. Besides their actual function of storing electrical drive energy, the batteries or battery modules are often integrated into the vehicle's load-bearing structure. They either form load-bearing components themselves or possess sufficient strength to minimize the risk of damage to the battery module in the event of an accident. A very high rigidity of the overall module is also crucial, as it significantly influences the vehicle's stiffness and handling characteristics. Therefore, currently, very complex frame structures around the actual battery cells, made of extruded profiles or formed parts, are common.As a rule, the actual battery compartment must also contribute to the rigidity in order to achieve a compromise between battery capacity and vehicle rigidity.

[0003] In practice, for example, in battery modules with so-called cylindrical cells (individual battery cells with a cylindrical housing), foams or potting compounds are used to fill the entire space around the individual battery cells within the housing. This securely fixes the cells and ensures sufficient rigidity for the entire battery cell assembly. However, this is both complex and expensive, and often causes problems when the battery is recycled. This is because the adhesive or potting compound cannot be recycled, and the embedding of the individual battery cells in the adhesive creates structures that are very difficult to disassemble. Such adhesives and / or potting compounds are also problematic in manufacturing, as they are often hazardous to health.Furthermore, applying the adhesive, for example with glue guns, is correspondingly complex and requires a significant amount of time for cleanup. Disposing of leftover adhesive is also often very difficult.

[0004] DE 10 2013 020 942 A1 describes a battery module structure with flat cells, which have intermediate frames, for example made of sheet metal, that simultaneously serve as cell connectors and are welded together for electrical contact. A similar structure is described in generic DE 10 2021 131 506 A1, also for cylindrical cells.

[0005] Other similar structures with round cells, in which, unlike in the generic document, a welded connection of the base, intermediate plates and lid is omitted, are known from DE 10 2022 128 743 A1 and DE 10 2022 103 690 A1.

[0006] For further general information on the state of the art regarding the use of cylindrical cells, reference can be made to DE 10 2021 124 360 A1, which essentially describes cell connectors that can be attached to the ends of cylindrical cells to connect with the part of the housing forming one battery terminal of the cylindrical cell.

[0007] In light of the above, it would now be desirable to provide a battery module with high mechanical stiffness and stability, which is nevertheless easy to construct and can also be easily recycled if necessary.

[0008] According to the invention, this problem is solved by a battery module having the features of claim 1, and in particular those of the characterizing part of claim 1. Advantageous embodiments and further developments are described in the dependent claims.

[0009] In the battery module according to the invention, the individual battery cells are designed as cylindrical cells. They are arranged between intermediate plates, the intermediate plates having indentations extending transversely to a longitudinal direction, in each of which at least one of the individual battery cells is arranged with a portion of its circumference. Ideally, one of the individual battery cells is placed in the respective indentation, but several are also possible. Preferably, these are then arranged with their central axes aligned.

[0010] The cylindrical cells are thus held between intermediate plates, each of which has indentations corresponding to a portion of the circumference of the individual battery cell. The cylindrical cells can be positioned in these indentations and covered by another intermediate plate. This second plate also has indentations corresponding to the individual battery cells, allowing the individual battery cells to be held between the indentations of adjacent intermediate plates. The individual battery cells can be held in place mechanically, for example, by edges, protrusions, or similar features. Alternatively, a frictional or force-fit connection, achieved by pressing the intermediate plates together, is also possible. This arrangement eliminates the need for complex adhesives or the filling of gaps with expanding foam. Instead, the individual battery cells are securely held between their intermediate plates.The intermediate plates ensure high stability of the battery module, which can be arranged in a battery housing, for example, and the intermediate plates can be connected to the battery housing.

[0011] According to the invention, the intermediate sheets and / or the cell housings of the individual battery cells are coated with an electrically insulating layer. Such an electrically insulating coating ensures that the intermediate sheets primarily serve to stabilize the battery module and only come into electrical contact with the individual battery cells when explicitly desired. For this purpose, specific areas can be left uncoated with regard to the electrically insulating layer, or these areas can be freed from the electrically insulating layer during assembly, for example, mechanically by grinding or removing the coating using abrasive tools and / or materials, or, for example, by laser welding, which is already used for assembly.

[0012] Such a structure can be implemented, for example, with mechanical connections or, in particular, welded joints, to join the intermediate sheets and the housing. The materials used, such as steel and / or aluminum for the sheets, are readily available and inexpensive, and can be easily processed by creating the necessary indentations through methods such as bending, deep drawing, and / or embossing. The intermediate sheets can also be easily disassembled by removing the corresponding weld points using mechanical means such as grinding, sawing, or prying. This results in largely homogeneous materials, such as steel and / or aluminum, which are ideally suited for recycling.

[0013] Another very advantageous embodiment of the battery module according to the invention can provide that the individual battery cells are arranged at intervals from one another in several longitudinally extending rows, with the intermediate plates arranged between the rows. This creates a structure in which the individual rows of battery cells and the intermediate plates alternate, so that an overall mechanically very stable assembly can be achieved.

[0014] Another very advantageous embodiment of the battery module according to the invention can further provide that the intermediate sheets have alternating successive indentations on one and then the other surface in the longitudinal direction. The sheets can thus, for example, be bent in a wave-like manner, so that an indentation in one transverse direction alternates with one indentation in the other transverse direction in the longitudinal direction. This design is particularly well suited to achieving good contact between the cylindrical cells and the intermediate sheets, which contributes to the rigidity of the structure.

[0015] According to a further exceptionally advantageous embodiment of the battery module according to the invention, the indentations can also be designed as half-honeycombs. The indentations can thus be implemented in a honeycomb-like manner. Each indentation can form half of a preferably hexagonal honeycomb. If the indentations of adjacent intermediate plates then lie against each other, a structure with numerous hexagonal honeycombs is created, which completely fill the area. A round battery cell can then be inserted into each individual honeycomb, leaving only a small amount of free space if the distance between the honeycomb surfaces is structurally matched to the diameter of the battery cell.

[0016] The intermediate plates can be connected to a base plate along their end edges parallel to the longitudinal direction, according to a very advantageous design. This connection can, in principle, be implemented in any manner. Since the base plate is often designed as a cooled base plate or directly forms a cooling heat exchanger, it can be crucial to achieve a highly thermally conductive connection. In particular, a welded connection can be achieved using various welding processes such as laser welding, arc welding, friction stir welding, or arc welding. A mechanical connection, for example by riveting, or even by bolting or plugging, would also be conceivable.Another suitable joining technique could be gluing, although here the problem of the actually undesirable adhesive arises again, the amount of which in such a connection is so much smaller than in potting according to the aforementioned prior art that this would be quite tolerable.

[0017] A similar connection can also be achieved with a cover plate in the area of ​​the opposite end faces.

[0018] According to a highly advantageous further development, the intermediate plates themselves can also be connected to each other. Here, too, the variants described above are suitable for connecting the intermediate plates; in particular, they can be pressed onto the individual battery cells and then subsequently welded in the area of ​​the end edges.

[0019] A further exceptionally advantageous embodiment of the battery module according to the invention provides that the intermediate sheets have tabs on their end edges that are bent parallel to the longitudinal direction or are suitable for bending. Such tabs, which are preferably arranged directly on the intermediate sheets and formed integrally with them, can, for example, be pre-bent, preferably by 90°, in order to allow the intermediate sheet to be positioned vertically, for example, on a base plate or cooling plate of the battery module. For example, the bent tabs can be welded to the base plate. The intermediate sheets then form a comparatively stable structure, in which individual battery cells can now be inserted laterally into the recesses, which are preferably designed as half-honeycombs, before the next intermediate sheet is placed on top and clamped to the first intermediate sheet.Then its bent tabs can also be welded to the base plate. Welding the intermediate plates to each other is also conceivable.

[0020] In addition to attaching the intermediate plates to a base or top plate of a housing for the battery module using the tabs, it is also possible to bend the tabs during the manufacturing of the battery module. In this case, for example, several intermediate plates can already be welded to the base plate, creating a honeycomb pattern with the intermediate plates positioned vertically on the base plate. One of the individual battery cells, designed as a cylindrical cell, can then be inserted into each individual cell from above. The tabs on the intermediate plates that extend upwards above the top edge of the individual battery cell can then be easily and efficiently crimped or bent over to mechanically hold the individual battery cell within its respective cell.If the height of the intermediate plates is greater, in principle two - or more - aligned round cells could also be inserted into the same honeycomb and joined together.

[0021] As mentioned above, depending on the arrangement, the intermediate plates and / or tabs can be additionally welded as needed. In particular, the structure can also be closed off at the top with a cover plate, which can be welded to the bent tabs.

[0022] Further advantageous embodiments of the battery module according to the invention also result from the exemplary embodiment, which is described in more detail below with reference to the figures.

[0023] This shows: Fig. 1 a schematic sectional view through a battery module according to the invention; Fig. 2 a schematic top view of several intermediate plates of a battery module according to the invention, which are connected to a base plate; Fig. 3 a schematic sectional view according to line III - III in Fig. 1; Fig. 4 a representation analogous to the one in Fig. 3 in an alternative embodiment; Fig. 5 a view analogous to the one in Fig. 3 using the example of a parallel connection of the individual battery cells; Fig. 6 a structure analogous to the one in Fig. 3 before attaching the individual battery cells; Fig. 7 the structure according to Fig. 6 after attaching the individual battery cells; Fig. 8 the structure according to Fig. 7 with multiple individual battery cells; Fig. 9 the structure according to Fig. 8 with an attached cover plate; and Fig. 10 a top view of a battery module assembly according to Fig. 8.

[0024] In the presentation of the Fig. Figure 1 shows a schematic section of the essential components for the construction of a possible embodiment of a battery module 1 according to the invention.

[0025] The structure begins with the presentation of the Fig. 1. From bottom to top, a first intermediate plate 2, which is essentially corrugated and has alternating upward and downward directed indentations, each forming half a hexagonal honeycomb. Individual battery cells 3 are inserted into the upward-facing indentations of this first intermediate plate 2. They form a first row in a longitudinal direction L running transversely to the plane of the drawing and along the greatest extent of the first intermediate plate 2. A second intermediate plate 4 is then placed on top of this first row of individual battery cells 3, so that its downward-facing indentations now completely enclose the individual battery cells 3. It is thus positioned offset in the longitudinal direction L by one indentation relative to the first intermediate plate 2. In the area where the upward-facing indentations of the second intermediate plate 4 are located, the intermediate plates 2 and 4 are in contact.They can be connected to each other in this area if needed.

[0026] Battery cells 5, designated as such, from a second upper row of battery cells 5 are now inserted into the upward-facing recesses of the second intermediate plate 4. The battery cells 3 of the lower row and 5 of the upper row are spaced apart from each other so that they can each accommodate half of the battery cells 3 and 5 of the other row. This assembly is then completed by a third intermediate plate 6, which is essentially designed and arranged like the first intermediate plate 2. This assembly extends in width, i.e., in the longitudinal direction L in the representation of the Fig. 1 according to the desired size of the battery module 1, so that in practice each of the rows of individual battery cells 3, 5 will certainly have more than the three exemplary individual battery cells 3, 5 shown here. In the vertical direction, this structure will typically also extend over several such rows of individual battery cells 3, 5, between which one of the intermediate plates 2, 4, 6 is then arranged.

[0027] All or some of the intermediate plates 2, 4, 6 can now be shown in the representation of the Fig. 2 recognizable tabs, designated 7, which are made of the same material as the intermediate plates 2, 4, 6 and are typically formed integrally with them. They can then be bent, for example at an angle of 90°, to fit the intermediate plates 2, 4, 6, as shown in the illustration of the Fig. As can be seen in Figure 2, the device can be set up on a base plate 8. All or some of the tabs 7 are then welded to this base plate 8 via indicated laser welds 9, thus creating a stable structure consisting of the base plate and the correspondingly arranged intermediate plates 2, 4, 6. The individual battery cells 3, 5 can then be inserted into the open honeycomb spaces between the individual intermediate plates 2, 4, 6, which are formed by the indentations in the respective intermediate plates 2, 4, 6.

[0028] In the presentation of the Fig. 3. This structure is shown in a schematic section along line III - III in Fig. Figure 1 shows the base plate 8 at the bottom. In the embodiment shown here, the intermediate plate 2, then the intermediate plate 4, and the intermediate plate 6 with their respective bends 7 are positioned on this plate at the far left. The laser welds 9 between the corresponding intermediate plates 2, 4, 6 and the base plate 8, which can be designed as a cooled base plate 8, are indicated by the black triangles.

[0029] Furthermore, for electrical insulation of a cell housing 10 of the battery cell 3 (which applies analogously to the battery cells 5 of the other row), a thermal paste 11 or a thermal pad is arranged between the bottom of the cell housing 10 and the tabs 7 or the cooled base plate 8. Additionally, the intermediate sheets 2, 4, 6 are each provided with an electrically insulating coating 12, shown here with cross-hatching. This design ensures that there are no unwanted electrical connections. However, in those areas where the intermediate sheets 2, 4, 6 must be welded, this coating 12 must be removed beforehand. To increase mechanical stability, for example, the [missing information] are also [missing information]. Fig. The end faces of the intermediate plates 4 and 6, shown in the upper right, are welded together. This weld is also indicated by a black triangle, analogous to welds 9, and is marked with reference numeral 13.

[0030] The setup can be implemented even more easily and efficiently if, as shown in the illustration of the Fig. As can be seen in Figure 4, the cell housing 10 itself has the electrically insulating coating 12. This electrical insulation is shown here as a sheath around the cell housing 10 of the individual battery cell 3, 5. In this case, an electrically insulating coating 12 of the intermediate sheets, here intermediate sheets 4 and 6, can be omitted, so that they can be welded directly to each other and to the base plate 8 without preparation. Here, too, a thermal paste 11 is schematically indicated between the bottom of the cell housing 10 and the contact on the tab 7 or the base plate 8. In the illustration of the Fig. In the area of ​​the intermediate plate 6, an optional tab 7 can also be seen at the top, which is connected via a further welded connection 16 to a Fig. 9, which is explained in more detail below, can be connected to the cover plate 15.

[0031] Another possibility of dispensing with both the electrically insulating coating 12 of the intermediate sheets 2, 4, 6 and the electrical insulation of the cell housing 10 exists if, as shown in the illustration of the Fig. As indicated in Figure 5, a parallel connection of adjacent battery cells 3 and 5 is to be made. In this case, the materials can be welded directly together, as shown in the schematic representation of the Fig. 5 is indicated. The cell housings 10, which typically form the negative cell pole, are thus electrically connected via the intermediate plates 4, 6. Furthermore, in Fig. 5 a cell connector 19 can be seen, which electrically connects the cell poles 18 protruding upwards from the cell housing 10 of the battery individual cells 3, 5 via welds 20.

[0032] The individual battery cells 3, 5 can now be inserted between the intermediate plates 2, 4, 6 and pressed into place, as described above. They can be held between the intermediate plates 2, 4, 6 solely by pressing, i.e., by frictional connection, or they can also be bonded or welded to them. An alternative embodiment is shown in the illustration of the Fig. 6 and Fig. 7 indicated. Here too, analogous to the representation in Fig. 2. The corresponding honeycomb structure is produced from the corresponding indentations of the two intermediate plates 2, 4 by welding their lower tabs 7 to the base plate 8 via the weld seam 9. In the illustrated embodiment, the electrically insulating coating 12 is again indicated on both surfaces of the intermediate plates 2, 4 that are in contact with the cell housings 10 of the individual battery cell 5, 3. After the individual battery cell 3, 5 is inserted into the corresponding honeycomb structure between the intermediate plates 2, 4, further upwardly projecting tabs 7 of these two intermediate plates are bent inwards over the cell housing 10 of the individual battery cell 3, 5, as shown in the illustration after completion of the process. Fig. 7 can be seen. The individual battery cell 3, 5 is now mechanically fixed within its honeycomb structure.

[0033] Fig. Figure 8 shows the same structure again using the example of two adjacent battery cells 3, 5, where here the insulating coating 12 on the upward-facing parts of the crimped tabs 7 has been removed for subsequent welding. The structure according to Fig. 8 is analogous to the representation in Fig. 1 also again in the presentation of the Fig. Figure 10 shows a top view, clearly revealing that three of the folded tabs 7 hold each individual battery cell 3, 5 in the honeycomb structure formed by the indentations. Here too, the two adjacent intermediate plates 4, 6, located between the two individual battery cells 3, 5 shown, are connected to each other via the weld seam designated 13.

[0034] Furthermore, as mentioned above, the upward-facing parts of intermediate plates 2, 4, 6 and the intermediate plate shown on the far right, labeled 14, are finished with a bare metal surface. This structure can now be used as described in Fig. As shown in Figure 9, a cover plate 15 is placed on top, which can be welded to the respective folded-over tabs 7 of the intermediate plates 2, 4, 6, 14 via welds 16. The cover plate 15 has corresponding recesses 17 to allow electrical contact between the individual battery cells 3, 5.

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