DE102024205937A1 - Method for manufacturing a battery cell assembly and a battery cell assembly - Google Patents

Abstract

The invention relates to a method for manufacturing a battery cell assembly comprising a provisioning step in which a first battery cell (3) with a first cell terminal (5) and a second battery cell (7) with a second cell terminal (9) as well as a connecting element (11) are provided, and an joining step in which the first cell terminal (5) is joined to the second cell terminal (9) by means of the connecting element (11). According to the invention, it is provided that in the joining step the first cell terminal (5) is joined to the second cell terminal (9) by means of the connecting element (11) by shrinking the connecting element (11) onto the first cell terminal (5) and onto the second cell terminal (9), and/or that in the joining step the first cell terminal (5) is joined to the second cell terminal (9) by means of the connecting element (11) by cold stretching or stretching the first cell terminal (5) and/or the second cell terminal (9) into the connecting element (11).

Description

The invention relates to a method for manufacturing a battery cell arrangement according to the preamble of claim 1 and to a battery cell arrangement according to claim 10.

A battery for, for example, an electric vehicle, has a battery cell assembly consisting of several battery cells. In a generic method for manufacturing the battery cell assembly, a first battery cell with a first cell terminal, a second battery cell with a second cell terminal, and a connecting element are first provided in a preparation step. Subsequently, the connecting element is welded to the first and second cell terminals by laser welding in a joining step, so that the first and second battery cells are in a metallurgical welded connection via the connecting element. This method has the disadvantage that the manufacturing of the battery cell assembly is complex and expensive. Furthermore, the metallurgical welded connection makes reworking or repairing the battery cell assembly more difficult.

From the US 2013/0157104 A1 A releasable connector and a method for connecting two parts using the connector are known.

One object of the invention is to provide a method for manufacturing a battery cell arrangement by means of which the battery cell arrangement can be manufactured simply and cost-effectively.

This problem is solved by the features of the independent claims. Preferred embodiments of the invention are disclosed in the dependent claims.

The invention proposes a method for manufacturing a battery cell arrangement comprising a provisioning step in which a first battery cell with a first cell pole and a second battery cell with a second cell pole, as well as a connecting element, are provided, and an joining step in which the first cell pole is joined to the second cell pole by means of the connecting element. According to the invention, in the joining step, the first cell pole is joined to the second cell pole by means of the connecting element by shrinking the connecting element onto the first cell pole and onto the second cell pole, and/or in the joining step, the first cell pole is joined to the second cell pole by means of the connecting element by cold stretching or stretching the first cell pole and/or the second cell pole into the connecting element. By means of the connecting element, a mechanical and/or an electrical connection between the first cell pole and the second cell pole is established after and/or during the shrinking process. Additionally, the electrical connection can also be partially or completely established directly between the first and second cell terminals. Because the connector is simply shrunk onto the cell terminals, no complex equipment, such as a welding machine, is required to create the joint. Furthermore, no complex processes, such as those involved in welding, are necessary during the shrink-fitting process, making the battery cell assembly simple and cost-effective to manufacture. Additional advantages of shrink-fitting include the ability to compensate for form and positional tolerances and the mechanically robust connection of the cell terminals, resulting in a stable battery cell assembly. Additionally, shrink-fitting eliminates the risk of accidentally damaging a battery cell, specifically its active material, with a laser beam used in laser welding.

In order to enable uniform radial shrinkage of the connecting element onto the cell poles, in an exemplary embodiment it is provided that the connecting element has the form of a ring, preferably closed, particularly preferably round or rectangular, wherein it is preferably provided that an inner circumferential surface of the connecting element limits a passage to the radial outside, preferably associated with the connecting element, and/or wherein it is preferably provided that the connecting element is rotationally symmetric about an axis of rotation or that the connecting element is rotationally symmetric about an axis of rotation, preferably 4-fold.

In order to be able to slide the connecting element over the cell poles and, if necessary, break up an oxide layer of the connecting element, an exemplary embodiment provides that the method includes a heating and/or cooling step in which the connecting element is heated to a heating temperature, preferably compared to the ambient temperature, and/or the first cell pole and/or the second cell pole is cooled to a cooling temperature, preferably compared to the ambient temperature, so that the connecting element, preferably with respect to an axis of rotation or a rotation axis of the connecting element, moves according to expands radially outwards and/or so that the first cell pole and/or the second cell pole contracts, wherein it is preferably provided that the first cell pole and the second cell pole are not heated during the process, preferably before the start of the joining step, or preferably at least not actively heated.

In order to ensure that the connecting element can be reliably and without interference contours pushed over the cell poles, a preferred embodiment provides that the heating temperature is higher than the temperature of the first cell pole and/or the second cell pole, and/or that the cooling temperature is lower than the temperature of the connecting element.

For example, it is provided that the heating and/or cooling step is carried out before the joining step, and/or that the heating temperature is chosen to be high enough to break up any oxide layer of the connecting element.

In order to reliably connect the cell poles during shrinking, an exemplary embodiment provides that the method includes a pre-assembly step in which the first cell pole and the second cell pole are inserted into a passage bounded to the outside by the connecting element, preferably in that the pre-assembly step is carried out after the heating and/or cooling step and/or before the joining step.

In order to be able to carry out the joining step quickly, in an exemplary embodiment it is provided that the heated connecting element is actively or passively cooled in the ambient air during the joining step by shrinking the connecting element onto the first cell pole and the second cell pole, and/or that the cooled first cell pole and/or the cooled second cell pole is actively or passively heated in the ambient air during the joining step by stretching or cold stretching the first cell pole and/or the second cell pole into the connecting element.

In order to achieve reliable shrinkage of the connecting element onto the cell poles, an exemplary embodiment provides that the connecting element shrinks radially inwards during cooling with respect to a rotational axis or a rotational axis of the connecting element, preferably that during cooling the connecting element is shrunk onto the first cell pole and/or onto the second cell pole, preferably by force-fit and/or form-fit, and/or preferably that the first cell pole and the second cell pole are pressed against each other over a surface area by the shrinkage, preferably along a common joining axis.

To achieve good current transfer between the cell poles during the joining process, a preferred embodiment provides that an inner circumferential surface of the connecting element and/or a first outer circumferential surface of the first cell pole and/or a second outer circumferential surface of the second cell pole is geometrically designed such that, due to shrinkage, preferably due to cooling, a first end face of the first cell pole facing the second cell pole is pressed against a second end face of the second cell pole facing the first cell pole, preferably along a common joining axis. It is preferably provided that the first cell pole has the shape of a truncated cone or a truncated pyramid, and particularly preferably that the first cell pole tapers towards the first battery cell, preferably along the common joining axis. Joining axis, tapered towards the second battery cell.

By way of example, it is provided that by pressing the first end face against the second end face during shrinking, preferably during cooling, of the connecting element, preferably along a common joining axis, the battery cells are positioned relative to each other at the same time.

For example, it is provided that the first cell pole has the shape of a cuboid or the shape of a cylinder, and/or that the second cell pole has the shape of a cuboid or the shape of a cylinder.

In order to obtain a mechanically stable battery cell arrangement during the joining step, an exemplary embodiment provides that, after completion of the joining step, a first section of the inner circumferential surface is pressed flat against the first outer circumferential surface of the first cell pole, and/or that, after completion of the joining step, a second section of the inner circumferential surface is pressed flat against the second outer circumferential surface of the second cell pole.

For illustrative purposes only and/or as an example, it is provided that the connecting element is a first one, belonging to the first battery cell. The connecting element has a first, second, and a second, third, surface facing the second battery cell, and the connecting element has a median plane extending parallel and centrally between the first and second surface. Preferably, the first section of the inner circumferential surface and the second section of the inner circumferential surface converge or merge into each other in the median plane and form an angle that opens radially inwards with respect to the axis of rotation.

For example, the procedure may include a test step in which the electrical connections of the battery cell assembly are checked and/or rework is carried out on the battery cell assembly.

The invention further proposes a battery cell arrangement, preferably manufactured using the method described above, comprising a first battery cell, a second battery cell, and a connecting element, wherein the first battery cell has a first cell pole, wherein the second battery cell has a second cell pole, and wherein the first cell pole is connected to the second cell pole by means of the connecting element, and wherein the first cell pole is joined to the second cell pole by means of the connecting element being shrink-fitted onto the first cell pole and the second cell pole. As already explained above with reference to the method, the battery cell arrangement can be manufactured simply and cost-effectively.

For illustrative purposes only, the battery cell assembly shown here comprises the first battery cell, the second battery cell, and the connecting element. Naturally, the battery cell assembly can also include more than two battery cells and more than one connecting element.

For illustrative purposes only, and/or by way of example, it is provided that the material of the connecting element is either electrically conductive or electrically non-conductive, preferably being copper or aluminum. The connecting element made of electrically non-conductive material has the advantage of being inexpensive to manufacture and having a low weight. The connecting element made of electrically conductive material has the advantage that the current transfer from the first cell terminal to the second cell terminal also occurs, at least partially, via the connecting element.

The following are descriptions of embodiments of the invention with reference to the accompanying figures.

• 1 in einer partiellen Seitenschnittansicht eine Batteriezellenanordnung;
• 2 in einer Seitenansicht eine erste Batteriezelle und eine zweite Batteriezelle und ein Verbindungselement;
• 3 in einer partiellen Seitenschnittansicht die erste Batteriezelle und die zweite Batteriezelle sowie das Verbindungselement in einem erwärmten Zustand zu Beginn eines Vormontageschrittes, und
• 4 in einer partiellen Seitenschnittansicht die erste Batteriezelle und die zweite Batteriezelle sowie das Verbindungselement in dem erwärmten Zustand nach Abschluss des Vormontageschrittes und vor Beginn eines Fügeschrittes.

They show:

• 1 A partial side-section view of a battery cell arrangement;
• 2 in a side view a first battery cell and a second battery cell and a connecting element;
• 3 in a partial side-section view the first battery cell and the second battery cell as well as the connecting element in a heated state at the beginning of a pre-assembly step, and
• 4 in a partial side section view the first battery cell and the second battery cell as well as the connecting element in the heated state after completion of the pre-assembly step and before the start of a joining step.

In the 1 A battery cell arrangement 1 is shown. The battery cell arrangement 1 has a first battery cell 3 with a first cell terminal 5 and a second battery cell 7 with a second cell terminal 9. Additionally, the battery cell arrangement 1 has a connecting element 11. The first cell terminal 5 and the second cell terminal 9 are connected via the connecting element 11. 1 The first cell pole 5 and the second cell pole 9 as well as the connecting element 11 are shown in section.

The first cell terminal 5 has the shape of a truncated cone and tapers towards the first battery cell 3. The second cell terminal 9 also has the shape of a truncated cone and tapers towards the second battery cell 7. Of course, cell terminals 5 and 9 can also have other shapes, such as a cuboid or a cylinder. The first cell terminal 5 is connected to the first battery cell 3 via a spacer element 13, which is integrally formed and made of the same material.

The second cell pole 9 is connected to the second battery cell 7 via a second spacer element 15 which is made of the same material and is integrally connected to the second cell pole 9.

The connecting element 11 is, here only as an example, formed by a closed ring. As this is shown in the 2 As shown, the connecting element 11 has an inner circumferential surface 21 which has a passage 23 associated with the connecting element 11, with respect to an axis of rotation R associated with the connecting element 11, The connecting element 11 is limited radially outwards. The connecting element 11 is, here only as an example, rotationally symmetrical about the axis of rotation R.

The connecting element 11 has a first cover surface 25 facing the first battery cell 3 and a second cover surface 27 facing the second battery cell 3. A median plane M associated with the connecting element 11 extends centrally between and parallel to the cover surfaces 25 and 27. The inner circumferential surface 21 has a first section 31 and a second section 33. The first section 31 transitions into the second section 33 in the median plane M. 2 The connecting element 11 is shown in a longitudinal cross-section, with the axis of rotation R extending in the section plane associated with the longitudinal section. In the longitudinal cross-section, the first section 31 and the second section 33 together enclose an angle that opens radially inwards with respect to the axis of rotation R.

The first cell pole 5 is joined to the second cell pole 9 by means of the connecting element 11, such that the connecting element 11 is shrunk onto both the first cell pole 5 and the second cell pole 9. The connecting element 11 is shrunk onto both the first cell pole 5 and the second cell pole 9 in such a way that the first section 31, with respect to the axis of rotation R, is pressed radially inward against a first outer circumferential surface 35 of the first cell pole 5, generating mechanical stresses in the connecting element 11. The connecting element 11 is also shrunk onto the second cell pole 9 in such a way that the second section 33, with respect to the axis of rotation R, is pressed radially inward against a second outer circumferential surface 37 of the second cell pole 9, generating mechanical stresses in the connecting element 11.

Because the first section 31 extends radially inwards from the median plane M towards the first cover surface 25 and with respect to the axis of rotation R, and because the second section 33 extends radially inwards from the median plane M towards the second cover surface 27 and with respect to the axis of rotation R, a first end face 41 of the first cell pole 5 and a second end face 43 of the second cell pole 9 are pressed together along a common joining axis F in the shrunk-on connecting element 11. Because the end faces 41 and 43 are pressed together in the battery cell arrangement 1, electrical current can be reliably transferred from the first end face 41 to the second end face 43. The material of the connecting element 11 can therefore be electrically conductive and, for example, comprise copper or aluminum, so that current transfer from the first battery cell 3 to the second battery cell 7 via the connecting element 11 is also possible. Alternatively, the material of the connecting element 11 can also be electrically non-conductive, in which case the current transmission takes place solely via the end faces 41 and 43.

The following is based on the 1 , 2 , 3 until 4 A method for manufacturing the battery cell assembly 1 is described. The method comprises a provisioning step, a heating step, a pre-assembly step, a joining step, and a testing step.

In the provisioning step, the first battery cell 3 with the first cell terminal 5 and the second battery cell 7 with the second cell terminal 9, as well as the connecting element 11, are initially provided. The process status after completion of the provisioning step is described in the 2 depicted.

The heating step is performed immediately following the provisioning step. During the heating step, the connecting element 11 is heated to a heating temperature using a heat source (not shown), causing it to expand radially outwards with respect to the axis of rotation R. Consequently, the opening 23 also expands radially outwards with respect to the axis of rotation R. The first cell pole 5 and the second cell pole 9, however, are not actively heated, and their temperature remains at ambient temperature. The heating temperature is therefore significantly higher than the temperature of the first cell pole 5 and the second cell pole 9. The process status after completion of the heating step is shown in the 3 depicted.

The pre-assembly step is carried out immediately following the heating step. In this step, the first cell pole 5, the second cell pole 9, and the heated connecting element 11 are arranged relative to each other in preparation for the subsequent joining step. With the connecting element 11 heated, the first cell pole 5 and the second cell pole 9 are inserted into the opening 23 such that the first end face 41 and the second end face 43 are located within the opening 23 and extend parallel to each other at a distance. The process status after completion of the pre-assembly step is described in the 4 depicted.

Immediately following the heating step, the joining step is carried out, in which the parts of the battery cell assembly 1, arranged relative to each other, are joined together. For this purpose The connecting element 11 is actively cooled, for example by means of a blower, or passively by ambient air. During cooling, the connecting element shrinks radially inwards with respect to the axis of rotation R, so that the connecting element 11 is shrunk onto the first cell pole 5, specifically the first outer circumferential surface 35, and onto the second cell pole 9, specifically the second outer circumferential surface 37, forming the battery cell arrangement 1. In this process, the first cell pole 5, specifically the first end face 41, and the second cell pole 9, specifically the second end face 43, are pressed together along the common joining axis F. After completion of the joining step, the axis of rotation R is aligned with the common joining axis F. The process state after completion of the joining step is described in the 1 depicted.

The testing step is performed immediately following the assembly step. During this step, the electrical connections of battery cell assembly 1 are checked for proper functionality. Optionally, rework can also be carried out on the battery cell assembly during this testing step.

It should also be noted that the inner circumferential surface 21 can, for example, also be smooth cylindrical. As an alternative to the smooth cylindrical design or the inclined sections 31 and 33, the inner circumferential surface 21 can have undercuts. Furthermore, the connecting element 11 can have a spring element or sensor contacts.

Reference symbol list

1

Battery cell arrangement

3

first battery cell

5

first cell pole

7

second battery cell

9

second cell pole

11

Connecting element

13

first spacer element

15

second spacer element

21

Inner perimeter area

23

passage

25

first surface

27

second surface

31

first section

33

second section

35

first outer perimeter surface

37

second outer perimeter surface

41

first front surface

43

second front surface

F

joining axis

M

Middle level

R

axis of rotation

QUOTES INCLUDED IN THE DESCRIPTION

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

• US 2013/0157104 A1 [0003]

Claims (10)

A method for manufacturing a battery cell assembly comprising: a provisioning step in which a first battery cell (3) with a first cell pole (5) and a second battery cell (7) with a second cell pole (9) as well as a connecting element (11) are provided, and an joining step in which the first cell pole (5) is joined to the second cell pole (9) by means of the connecting element (11), characterized in that in the joining step the first cell pole (5) is joined to the second cell pole (9) by means of the connecting element (11) by shrinking the connecting element (11) onto the first cell pole (5) and onto the second cell pole (9), and/or that in the joining step the first cell pole (5) is joined to the second cell pole (9) by means of the connecting element (11) by cold stretching or stretching the first cell pole (5) and/or the second cell pole (9) into the connecting element (11). Procedure according to Claim 1 , characterized in that the connecting element (11) has the form of a ring, preferably closed, wherein it is preferably provided that an inner circumferential surface (21) of the connecting element (11) defines a passage (23) to the radial outside, preferably associated with the connecting element (11), and/or wherein it is preferably provided that the connecting element (11) is rotationally symmetric about an axis of rotation (R) or that the connecting element (11) is rotationally symmetric about an axis of rotation. Procedure according to Claim 1 or 2 , characterized in that the method comprises a heating and/or cooling step in which the connecting element (11) is heated to a heating temperature and/or the first cell pole (5) and/or the second cell pole (9) is cooled to a cooling temperature, preferably in comparison to the ambient temperature, so that the connecting element (11) expands radially outwards with respect to an axis of rotation (R) of the connecting element (11) and/or so that the first cell pole (5) and/or the second cell pole (9) contracts, wherein it is preferably provided that the first cell pole (5) and the second cell pole (9) are not heated, preferably at least not actively, in the method, preferably before the start of the joining step. Procedure according to Claim 3 , characterized in that the heating temperature is higher than the temperature of the first cell pole (5) and/or the second cell pole (9), and/or that the cooling temperature is lower than the temperature of the connecting element (11). Method according to one of the preceding claims, characterized in that the method comprises a pre-assembly step in which the first cell pole (5) and the second cell pole (9) are inserted into a passage (23) bounded to the outside by the connecting element (11), wherein it is preferably provided that the pre-assembly step is carried out after the heating and/or cooling step and/or before the joining step. Procedure according to one of the Claims 3 until 5 , characterized in that the heated connecting element (11) is actively or passively cooled in the ambient air during the joining step by shrinking the connecting element (11) onto the first cell pole (5) and the second cell pole (9), and/or that the cooled first cell pole (5) and/or the cooled second cell pole (9) is actively or passively heated in the ambient air during the joining step by stretching or cold stretching the first cell pole (5) and/or the second cell pole (9) into the connecting element (11). Procedure according to Claim 6 , characterized in that the connecting element (11) shrinks radially inwards during cooling with respect to an axis of rotation (R) of the connecting element (11) or a rotation axis of the connecting element (11), wherein it is preferably provided that during cooling the connecting element (11) is shrunk onto the first cell pole (5) and/or onto the second cell pole (9), preferably by force-fit and/or form-fit, and/or wherein it is preferably provided that the first cell pole (5) and the second cell pole (9) are pressed against each other over a surface by the shrinking, preferably along a common joining axis (F). A method according to one of the preceding claims, characterized in that an inner circumferential surface (21) of the connecting element (11) and/or a first outer circumferential surface (35) of the first cell pole (5) and/or a second outer circumferential surface (37) of the second cell pole (9) is geometrically designed such that, due to shrinkage, preferably due to cooling, a first end face (41) of the first cell pole (5) facing the second cell pole (9) is pressed against a second end face (43) of the second cell pole (9) facing the first cell pole (5), preferably along a common joining axis (F), wherein it is preferably provided that the first cell pole (5) has the shape of a truncated cone or a truncated pyramid, wherein it is particularly preferably provided that the first cell pole (5) extends in the direction of the first cell pole (5), preferably along the common joining axis (F). ten battery cell (3) tapers, and/or wherein it is preferably provided that the second cell pole (9) has the shape of a truncated cone or a truncated pyramid, wherein it is particularly preferably provided that the second cell pole (9) tapers, preferably along the common joining axis (F), in the direction of the second battery cell (7). Procedure according to Claim 8 , characterized in that, after completion of the joining step, a first section (31) of the inner circumferential surface (21) is pressed flat against the first outer circumferential surface (35) of the first cell pole (5), and/or that, after completion of the joining step, a second section (33) of the inner circumferential surface (21) is pressed flat against the second outer circumferential surface (37) of the second cell pole (9). Battery cell arrangement, preferably manufactured by the method according to one of the preceding claims, comprising: a first battery cell (3), a second battery cell (7), and a connecting element (11), wherein the first battery cell (3) has a first cell pole (5), wherein the second battery cell (7) has a second cell pole (9), and wherein the first cell pole (5) is joined to the second cell pole (9) by means of the connecting element (11), and wherein the first cell pole (5) is joined to the second cell pole (9) by means of the connecting element (11) in that the connecting element (11) is shrunk onto the first cell pole (5) and onto the second cell pole (9).