DE102023125810A1 - Method for producing a battery with round cells and battery for a motor vehicle - Google Patents

Abstract

The invention relates to a The invention relates to a battery (10) for a motor vehicle, comprising a cell arrangement (12) with a plurality of first round cells (14), each having the same first cell diameter (D1), and which are arranged relative to one another according to a first pattern, with first intermediate spaces (18) being located between the first round cells (14). The battery (10) comprises a plurality of second round cells (16), each having the same second cell diameter (D2), which is different from the first cell diameter (D1), with the second round cells (16) being arranged in at least some of the first intermediate spaces (18).

Description

The invention relates to a battery for a motor vehicle, comprising a cell arrangement with a plurality of first round cells, each of which has an identical first cell diameter and is arranged relative to one another according to a first pattern, with first gaps between the first round cells. Furthermore, the invention also relates to a method for producing a battery.

In a battery, especially a motor vehicle battery, the aim is to arrange battery cells as closely together as possible so that there are as few empty spaces between the cells as possible. However, especially with round cells, there will always be gaps between the battery cells. Two arrangement patterns have proven advantageous: hexagonal circular packing, in which a round cell is surrounded by six nearest neighboring cells, and square circular packing, in which the cells are arranged in non-offset rows and columns, so that the centers of four cells, two of each of two adjacent cell rows, form the corners of a square. The theoretical maximum space utilization according to hexagonal circular packing is a maximum of 90.7%. If this closest circular packing is not possible or not feasible in the given installation space, so-called square circular packing is used. This achieves a maximum packing density of only 78.5%. If hexagonal circular packing is the goal, the battery cells generally have to be built small. This requires a high level of integration into the battery, which is known to be a significant disadvantage of round cells compared to prismatic battery cells and pouch cells. However, with larger cells, the likelihood of having to resort to square packaging increases, which, however, results in significantly lower space utilization.

The DE 10 2010 043 716 A1 describes a battery arrangement in which heat exchange elements of a temperature control device are provided in an intermediate space between adjacent lithium-ion battery cells, through which a heat exchange medium can flow in order to exchange heat with the heat to control the temperature of the lithium-ion battery cells.

Spaces between the cells can be used to accommodate other components, such as heat exchangers, but this does not improve the space utilization of the battery cells themselves and thus the volumetric energy density.

The object of the present invention is therefore to provide a battery with round cells and a method which make it possible to provide the greatest possible volumetric energy density of the cell arrangement.

This object is achieved by a battery and a method having the features according to the respective independent patent claims. Advantageous embodiments of the invention are the subject of the dependent patent claims, the description, and the figures.

A battery according to the invention for a motor vehicle comprises a cell arrangement with a plurality of first round cells, each having an identical first cell diameter, and arranged relative to one another according to a first pattern, with first spaces between the first round cells. The battery comprises a plurality of second round cells, each having an identical second cell diameter that differs from the first cell diameter, with the second round cells being arranged in at least some of the first spaces.

The spaces between the first round cells can now be advantageously used to accommodate additional round cells with a different cell diameter, namely the second round cells. This advantageously increases the volumetric energy density. This also simplifies the use of larger round cells, for example, than the first round cells, since the resulting larger spaces do not remain unused but can be used to accommodate additional round cells, namely the second round cells. This significantly improves the overall utilization of the installation space.

A round cell is generally understood to mean a battery cell, e.g., a lithium-ion cell, that has a substantially cylindrical geometry. Relative to the cylinder axis of such a cylindrical geometry, the first and second round cells can be configured with substantially the same height. The round cells, i.e., both the first round cells and the second round cells, can be arranged relative to one another in the cell arrangement such that they touch at their lateral surfaces, or they can also have a certain distance from one another, which is then preferably significantly smaller than the first and/or second cell diameter, e.g., by approximately one order of magnitude. Furthermore, the round cells, i.e., both the first round cells and the second round cells, are arranged relative to one another in the cell arrangement such that their respective cylinder axes are essentially aligned parallel to each other.

The first and second round cells can be, for example, lithium-ion cells. The battery can be designed, for example, as a high-voltage battery. In particular, the battery should preferably be a traction battery for a motor vehicle, in particular an electric vehicle.

In a further advantageous embodiment of the invention, the first pattern represents a regular pattern. The first pattern can be provided, for example, by one of the sphere packings mentioned above. A regular pattern repeats itself periodically, e.g., in one or two spatial directions. This simplifies the arrangement of the battery cells relative to one another and enables easy scalability of the cell arrangement.

According to a further advantageous embodiment of the invention, one of the second round cells is arranged in each first intermediate space not adjacent to an edge region of the cell arrangement. Thus, at least all "inner" intermediate spaces between the round cells can advantageously be used to provide one of the second round cells, in particular precisely one of the second round cells, therein. This allows for optimized space utilization.

According to a further advantageous embodiment of the invention, the second round cells are arranged relative to one another according to a second regular pattern. If the first round cells are arranged according to the first pattern, which represents a regular pattern, and one of the second round cells is arranged in each of the resulting internal spaces, this automatically results in a regular second pattern according to which the second round cells are arranged relative to one another. This is particularly advantageous because the arrangement of the battery structure or cell arrangement is then very simple, both for the first battery cells and for the second battery cells. The first pattern does not necessarily have to correspond to the second pattern. Especially if the first round cells are arranged relative to one another according to a hexagonal sphere packing, for example, the second round cells will have a different arrangement pattern. If the first round cells are arranged relative to one another according to a square sphere packing, for example, the second pattern of the second round cells will also be in the form of a square sphere packing, but with a greater distance from one another than for the first round cells, if the first round cells have a larger cell diameter than the second round cells.

In principle, either the first round cells can be larger than the second round cells in terms of cell diameter, or vice versa. Furthermore, according to the arrangement options described, not only are the round cells arranged in the first spaces between the first round cells, but conversely, first round cells are also arranged in second spaces between the second round cells. To simplify the description, however, it is assumed below that the first cell diameter is larger than the second cell diameter. The first round cells therefore represent the round cells with the larger cell diameter. The first and second round cells are then preferably arranged in such a way that minimal distances result between any two adjacent first round cells. The first round cells can therefore be arranged in such a way that they are placed as close to one another as possible, while the second round cells are then arranged in the available, remaining first spaces.

According to a further advantageous embodiment of the invention, the first round cells are arranged relative to one another according to the first pattern such that each of the first round cells that does not represent an edge cell has four first round cells as the first nearest neighboring cells. In the description of the first pattern, the second round cells are disregarded. In other words, a first round cell can also have second round cells as the nearest neighboring cells, which can then be called second nearest neighboring cells, but which are not considered here in the description of the first pattern. The first round cells can therefore be arranged relative to one another in the form of the square sphere packing described above. This first pattern can also be described such that a first center is assigned to each respective "inner" space, with the first round cells being arranged relative to one another according to the first pattern such that each first center of four first round cells adjacent to the space assigned to the first center is equidistant. The first round cells can therefore be arranged in rows and columns that are not offset from one another. The centers of the first round cells of a same row, based on a top view of the first round cells on their front sides, thus lie on a theoretical or imaginary line. Furthermore, several rows of such first round cells can be arranged next to each other in such a way that perpendicular to the rows Columns are formed, with the centers of the first round cells of the same column also lying on a straight, imaginary line perpendicular to the aforementioned imaginary line along the row. The centers of the first round cells, when connected by imaginary lines, form a square grid, so to speak.

As described above, such a square sphere packing has a lower packing density than the hexagonal sphere packing. However, by providing the additional second battery cells, the space utilization can be significantly increased more efficiently in the square sphere packing than, for example, in the hexagonal sphere packing. This increases, in particular, the theoretical packing density from the original 78.5% to 92.0%. As a result, a packing density can be achieved with the square sphere packing that even exceeds that of the conventional hexagonal sphere packing.

According to a further advantageous embodiment of the invention, the second cell diameter is between 30.0% and 55.0% of the first cell diameter. According to a theoretical model, according to which the first round cells are arranged in contact with one another according to the square sphere packing, and the second round cells are also arranged in the resulting spaces in contact with the four first round cells surrounding a respective second round cell, this results in a maximum possible second cell diameter of 41.0% of the first cell diameter. In the actual cell arrangement, the first round cells can be spaced apart by a certain distance. Furthermore, the second round cells do not necessarily have to be arranged in contact with the first round cells, so that more or less large distances can be provided here as well. Accordingly, the second cell diameter can also be slightly more or less than 41.0% of the first cell diameter. It is also very advantageous, for example, if the second cell diameter is between 35.0% and 45.0% of the first cell diameter. With these diameter ratios, a very high packing density can be achieved.

According to a further advantageous embodiment of the invention, the first round cells are arranged relative to one another according to the first pattern such that each of the first round cells that does not represent an edge cell has six of the first round cells as the first nearest neighboring cells. This essentially corresponds to the hexagonal sphere packing described above. The first pattern can be defined such that a first center is assigned to a respective first intermediate space, wherein the first round cells are arranged relative to one another according to the first pattern such that a respective first center of three first round cells adjacent to the first intermediate space assigned to the first center is at the same distance. The first round cells can therefore be arranged in several parallel rows, wherein two cell rows arranged adjacent to one another in a specific first direction are offset from one another in a second direction perpendicular to the first direction, in particular by at least the first cell diameter, and in particular by half the distance between the centers of two first round cells arranged adjacent to one another in the same cell row. Thus, essentially only three of the first round cells border a first intermediate space. If the first three round cells touch each other, the first gap is enclosed by these three round cells. Even with hexagonal sphere packing, the packing density can be increased, albeit not to the same extent as with square sphere packing, if the second round cells are arranged in the first gaps between the first round cells as described. This can also ultimately lead to an increase in the volumetric energy density of the cell arrangement.

Especially with this design, it is very advantageous if the second cell diameter is between 10.0% and 30.0% of the first cell diameter. Theoretically, the maximum possible second cell diameter, when the first and second round cells are arranged in such a way that they touch each other, is 15.5% of the first cell diameter. Here, too, however, more or less large distances can be provided between the first round cells and/or the second round cells. It is also advantageous, for example, if the second cell diameter is between 10.0% and 20.0% of the first cell diameter. This also makes it possible to increase the overall use of installation space and achieve a very high volumetric energy density, in particular a calculated maximum of 92.7%.

In any case, it is preferred, i.e. regardless of the selected first pattern according to which the first round cells are arranged relative to one another, that the second cell diameter is at least 8 mm. Starting with this very small cell diameter of at least 8 mm, a very economical cost-benefit ratio can be achieved. Such a small second cell diameter also enables the integration of the second round cells into the spaces between the first ten round cells arranged according to the hexagonal sphere packing, without having to dimension the first round cells excessively large. This ensures efficient use of space, especially in the edge regions. Furthermore, it enables more frequent use of the hexagonal sphere packing of the first round cells, even in situations where the square sphere packing would otherwise have to be used due to the inefficiency in the edge region.

An edge cell is, in particular, a round cell arranged at the edge of the cell arrangement. If the round cells are arranged, for example, in several rows, where these rows may or may not be offset from one another, then an edge cell has only one neighboring cell in the cell row direction relative to the direction in which the cell row is defined. In the case of inner round cells, each of these round cells has two neighbors relative to the cell row direction.

This also applies analogously to the above-mentioned spaces adjacent to the edge region. These outer spaces are formed at least partially between edge cells, in particular exclusively between edge cells.

Furthermore, the invention also relates to a motor vehicle with a battery according to the invention or one of its embodiments.

The advantages described for the batteries according to the invention and their configurations apply equally to the motor vehicle according to the invention.

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

Furthermore, the invention also relates to a method for producing a battery for a motor vehicle, wherein a cell arrangement is provided with a plurality of first round cells, each having an identical first cell diameter, and which are arranged relative to one another according to a first pattern, resulting in first spaces between the first round cells. A plurality of second round cells, each having an identical second cell diameter that differs from the first cell diameter, is provided, wherein the second round cells are arranged in at least some of the first spaces.

The invention also includes further developments of the method according to the invention that have features already described in connection with the further developments of the battery according to the invention. For this reason, the corresponding further developments of the method according to the invention are not described again here.

The invention also encompasses combinations of the features of the described embodiments. The invention therefore also encompasses implementations that each have a combination of the features of several of the described embodiments, unless the embodiments are described as mutually exclusive.

• 1 eine schematische Darstellung einer Batterie gemäß einem ersten Ausführungsbeispiel der Erfindung,
• 2 eine schematische Darstellung einer Batterie gemäß einem zweiten Ausführungsbeispiel der Erfindung.

Exemplary embodiments of the invention are described below. Shown are:

• 1 a schematic representation of a battery according to a first embodiment of the invention,
• 2 a schematic representation of a battery according to a second embodiment of the invention.

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 that can be considered independently of one another, each of which also develops the invention independently of one another. Therefore, the disclosure is intended to encompass combinations of the features of the embodiments other than those shown. 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 schematic representation of a battery 10 according to a first exemplary embodiment of the invention. The battery 10 has a cell arrangement 12. This comprises, on the one hand, a plurality of first round cells 14, of which, for reasons of clarity, only some are provided with a reference symbol. In addition, the cell arrangement 12 also comprises a plurality of second round cells 16, of which, likewise for reasons of clarity, only some are provided with a reference symbol. The round cells 14, 16 have a substantially cylindrical geometry. The cylinder axis of the respective round cells 14, 16 runs substantially parallel to the illustrated z-direction. The cell arrangement 12 is shown in a plan view of the end faces 14a, 16a of the respective round cells 14, 16. The first round cells 14 each have an identical first cell diameter D1 and the second round cells 16 each have an identical second cell diameter D2, which in this example is smaller than the first cell diameter D1. In addition, a first center point M1 can be defined for each first round cell 14, for example as the center point M1 of the corresponding end face 14a. In a corresponding manner, each second round cell 16 can also be defined as a center point M2, for example as the center point M2 of the corresponding end face 16a of the second round cell 16.

In this example, the first battery cells 14 are arranged relative to one another according to a square sphere packing as an example of the first pattern. The center points M1 of the first round cells 14 thus form a square grid, which is illustrated here by dashed lines. Between every four first round cells 14, a corresponding first intermediate space 18 is formed, in which one of the second round cells 16 is arranged. For a respective inner intermediate space 18 that does not border an edge region R, a center Z can be defined accordingly, which is at the same distance from the four first round cells 14 bordering the associated intermediate space 18. The second round cells 16 are preferably arranged in the respective intermediate spaces 18 such that their center points M2 coincide with the center Z of the respective intermediate space 18. The edge region R can be defined, for example, by a frame 20 of a battery housing 22 of the battery 10.

In addition, each round cell 14, 16 has an associated lateral surface 15, 17. The lateral surfaces of the first round cells 14 are designated by 15, and those of the second round cells 16 by 17. The first round cells 14 can be arranged relative to one another such that their respective lateral surfaces 15 touch, or they can also be spaced apart by a small distance, which is not explicitly shown here. The second round cells 16 can also be arranged in the intermediate spaces 18 such that they contact the surrounding first four round cells 14 or their lateral surfaces 15, or are spaced apart from them.

The second diameter D2 of each second round cell 16 is preferably at least 8 mm. Furthermore, the second diameter D2 is between 30.0% and 55.0% of the first cell diameter D1. In this example, namely in the case of a contacting arrangement, the second cell diameter D2 is approximately 41.0% of the first cell diameter D1. This allows the packing density of the square sphere packing, which would be approximately 78.5% without the second round cells 16, to be increased to approximately 92.0%. Thus, by additionally providing the second round cells 16 in the spaces 18 between the first round cells 14, the volumetric energy density of the battery pack, namely of the cell arrangement 12, can be significantly increased.

The respective cells 14, 16 can each have a substantially identical height in the z-direction shown. In principle, however, the cells 14, 16 can also be designed with different heights. By combining two round cells 14, 16 with a defined diameter ratio, a packing density maximization can be achieved. In practice, the diameter ratio may deviate slightly from the stated theoretical values.

2 shows a schematic representation of a battery 10 according to a further exemplary embodiment of the invention. This also has a cell arrangement 12, which in turn comprises first round cells 14 and second round cells 16. The first round cells 14 are in turn assigned a corresponding end face 14a, a first cell diameter D1, a first center point M1, and a lateral surface 15, and the second battery cells 16 are assigned a corresponding second end face 16a, a second cell diameter D2, a second center point M2, and a second lateral surface 17. In this example, the first round cells 14 are now arranged relative to one another according to a hexagonal sphere packing. Each of the first cells 14 that does not represent an edge cell 14' is surrounded by six first nearest neighboring round cells 14. Three of the first round cells 14 thus enclose an intermediate space 18, in which one of the second round cells 16 is arranged. A respective second round cell 16 is thus surrounded by three first battery cells 14. Each first battery cell 14, which in turn does not constitute an edge cell 14', is in turn surrounded by six second battery cells 16, and each second battery cell 16, which does not constitute an edge cell 16', is surrounded by three first round cells 14.

In this example, it is preferred that the second cell diameter D2 be between 10.0% and 30.0% of the first cell diameter D1. With an ideal diameter ratio between the first and second cell diameters D1, D2 of 1:0.155, the packing density for this hexagonal circular packing can also be increased from approximately 90.7% to approximately 92.7%, or by 2.0%. In this example, it is also preferred that the second cell diameter D2 be at least 8 mm.

The first and second round cells 14, 16 with different cell diameters D1, D2 can also be arranged relative to one another according to any other circular packing and arrangement patterns. Furthermore, it is conceivable for the cell arrangement 12 to comprise further battery cells with different cell diameters, for example, third battery cells with a third cell diameter that differs from the first and second cell diameters D1, D2.

Overall, the examples demonstrate how the invention can provide a mixed installation of two round cells, i.e., round cells with two different dimensions and a defined diameter ratio, to maximize packing density. By mixed installation of two round cells, i.e., round cells with two different diameters, the packing density can be maximized and the volumetric energy density of the battery pack can be increased accordingly. Furthermore, larger round cells can be used more easily, especially since gaps in edge areas can be filled and utilized more efficiently by providing additional smaller round cells.

QUOTES CONTAINED IN THE DESCRIPTION

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

Cited patent literature

• DE 10 2010 043 716 A1 [0003]

Claims (10)

Battery (10) for a motor vehicle comprising a cell arrangement (12) with a plurality of first round cells (14), each having the same first cell diameter (D1), and which are arranged relative to one another according to a first pattern, with first intermediate spaces (18) being located between the first round cells (14), characterized in that the battery (10) comprises a plurality of second round cells (16) each having the same second cell diameter (D2), which is different from the first cell diameter (D1), with the second round cells (16) being arranged in at least some of the first intermediate spaces (18). Battery (10) after Claim 1 , characterized in that the first pattern represents a regular pattern. Battery (10) according to one of the preceding claims, characterized in that one of the second round cells (16) is arranged in each of the first intermediate spaces (18) not adjacent to an edge region (R) of the cell arrangement (12). Battery (10) according to one of the preceding claims, characterized in that the second round cells (16) are arranged relative to one another according to a second regular pattern. Battery (10) according to one of the preceding claims, characterized in that the first cell diameter (D1) is larger than the second cell diameter (D2). Battery (10) according to one of the preceding claims, characterized in that the first round cells (14) are arranged relative to one another according to the first pattern such that each of the first round cells (14) which does not represent an edge cell (14') has four of the first round cells (14) as the first nearest neighboring cells. Battery (10) after Claim 6 , characterized in that the second cell diameter (D2) is between 30% and 55% of the first cell diameter (D1). Battery (10) according to one of the Claims 1 until 5 , characterized in that the first round cells (14) are arranged relative to one another according to the first pattern in such a way that each of the first round cells (14) which does not represent an edge cell (14') has six of the first round cells (14) as the first nearest neighboring cells. Battery (10) after Claim 8 , characterized in that the second cell diameter (D2) is between 10% and 30% of the first cell diameter (D1), and in particular is at least 8 mm. Method for producing a battery (10) for a motor vehicle, wherein a cell arrangement (12) is provided with a plurality of first round cells (14) which each have the same first cell diameter (D1) and which are arranged relative to one another according to a first pattern, so that first intermediate spaces (18) are formed between the first round cells (14), characterized in that a plurality of second round cells (16) are provided with a respective same second cell diameter (D2) which is different from the first cell diameter (D1), wherein the second round cells (16) are arranged in at least some of the first intermediate spaces (18).

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