WO2020177989A1

WO2020177989A1 - Battery having a plurality of battery cells

Info

Publication number: WO2020177989A1
Application number: PCT/EP2020/053494
Authority: WO
Inventors: Dirk Steffens; Christian Elsner; Michael Brandner
Original assignee: Daimler Ag
Priority date: 2019-03-06
Filing date: 2020-02-11
Publication date: 2020-09-10
Also published as: DE102019001603A1

Abstract

The invention relates to a battery, in particular for a motor vehicle, comprising a plurality of battery cells, which are electrically conductively interconnected. Components (34, 36) designed as bleeds of a particular battery cell are interconnected by welding, and/or at least one component (34) designed as a cell connector is connected to at least one component (36) designed as a bleed of one of the battery cells in a region of overlap of the components (34, 36) by welding. A first component (34) of the interconnected components (34, 36) has a planar contact region (42), in which the first component (34) is connected to a second component (36) of the interconnected components (34, 36) by the welding. The first component (34) has, in the contact region, one or more mutually adjacent bulges (38), which are formed toward the second component (36).

Description

Battery with a plurality of battery cells

The invention relates to a battery having a plurality of battery cells which are connected to one another in an electrically conductive manner. Here, components designed as arresters of a respective battery cell are connected to one another and / or at least one is used as a cell connector

formed component connected to at least one component formed as a conductor of one of the battery cells in an overlapping area of the components by welding.

For example, DE 10 2011 085 467 A1 describes that in a lithium-ion battery, the cell terminals of a respective battery cell by means of a

Cell connector can be connected electrically in series. It can be provided that the cell connector is placed on the cell terminals and through a single-type

To weld through the cell connector with the cell terminals. The

DE 10 2011 085 467 A1, however, suggests, due to the process engineering difficulties allegedly associated with this, materially connecting side surfaces of the cell terminals to a side edge surface of the cell connector, the side edge surface of the cell connector resting against the side surface of the cell terminal without a gap. This gap-free concern is to be achieved in the subject matter of DE 10 2011 085 467 A1 in that the respective cell connector has a curved deformation area. A deformation force can be applied to the deformation area in order to bring the side edge surfaces of the cell connector into contact with the side surfaces of the cell terminals of adjacent electrochemical cells.

A disadvantage here is the fact that this type of material connection requires high-precision manufacture of the cell terminals and the cell connector, and that the handling of the cell connector with regard to the application of the deformation force entails procedural difficulties. But also when welding components of batteries, which in one

Overlap area of the components are connected to one another by welding, difficulties can arise. This should be explained with reference to FIGS. 1 and 2.

A plurality of battery cells 12 of a battery 10 is shown in FIG. 1 schematically and in sections. In particular when the battery cells 12 are designed as lithium-ion cells, first arresters 14 of negative electrodes of the respective battery cell 12 can be formed by metal sheets or foils made of copper.

In contrast, second arresters 16 of positive electrodes of the respective battery cell 12 can be formed by metal sheets or foils made of aluminum. It can be seen from FIG. 1 that the first arresters 14 of two battery cells 12, which are formed from copper, are connected to one another in an overlapping area 18 via a weld 20. In an analogous manner, the second arresters 16 formed from aluminum of two further battery cells 12 are in a further overlapping area 22 over another

Weld seam 20 connected to one another.

In Fig. 1, a cell connector 24 is also shown, which in a first

Overlap area 26 is connected to at least one of the second arresters 16 via a further weld 20 and in a second overlap area 28 via yet another weld 20 with at least one of the first arresters 14. In such a contact with the battery cells 12 by the formation of

Welded connections, which can be achieved in particular by laser beam welding, can result from upstream bending operations of different sizes between components in the form of the arresters 14, 16 among one another and between the cell connector 24 and the arresters 14, 16. This should be explained with reference to FIG.

A first component is shown in FIG. 2, which can be, for example, the cell connector 24 or one of the arresters 14, 16. For example, consider the case that the cell connector 24 with the first arrester 14 via the

Weld 20 is to be connected. What has been said with reference to the components shown by way of example in FIG second arrester 16 in the overlap area 26. Accordingly, due to component inaccuracies, which can be caused by tolerances in previous forming operations, gaps 30 of different sizes can occur between the respective components, in the example shown in FIG. 2, for example, gap 30 between cell connector 24 and arrester 14.

Due to such gaps 30, the process reliability when forming the

Welded connection restricted by producing the welds 20. A laser beam 32 producing the respective weld seam 20 is shown schematically in FIG. 2. From FIG. 2 it can also be seen that due to the size of the gap 30 in

Vertical direction (z-direction), i.e. perpendicular to a flat extension of the im

Essentially flat components, in the event that a poor connection or no connection at all is achieved. This is also disadvantageous.

The object of the present invention is therefore to create a battery of the type mentioned at the beginning in which a particularly reliable electrically conductive connection between the components can be achieved.

This object is achieved by a battery with the features of claim 1. Advantageous configurations with expedient further developments of the invention are specified in the dependent claims.

The battery according to the invention, which can be provided in particular for a motor vehicle, comprises a plurality of battery cells which are electrically conductive

are connected to each other. Components designed as arresters of a respective battery cell are connected to one another by welding in an overlapping area of the components. Additionally or alternatively, at least one component designed as a cell connector is connected by welding to at least one component designed as an arrester for one of the battery cells in an overlapping area of the components. Here, a first component of the interconnected components has a flat contact area in which the first component is connected to a second component of the interconnected components by welding. The first component has in the

Contact area one or a plurality of juxtaposed

Bulges on which are formed towards the second component.

This is based on the knowledge that a geometric contour in the form of the at least one bulge that is introduced into the first component prior to welding enables a reliable bridging of a gap between the components during the Joining process is used. In the tensioned state, in which the first component is pressed against the second component, this bulge or contour produces a secure contact between the components to be welded together. In this case, the bulge behaves flexibly, since it is compressed more intensely when there is a gap of only a small height between the components than when there is a gap of greater height. By providing the at least one contour or bulge introduced into the first component, the connection between the components can be produced reliably by welding. As a result, a particularly reliable electrically conductive connection between the components can be achieved.

In particular, the process reliability during laser beam welding can be increased in this way. In addition, the corresponding process can be used flexibly for all weldable materials. In particular, a particularly reliable electrically conductive connection of the components to one another can also be established with mixed connections, for example the welding of a component made of aluminum to a component made of copper.

Furthermore, a reliable bridging of the gap by welding can also be achieved with sizes of a gap which are less than or equal to the height of the respective bulge. In addition, the at least one bulge ensures stiffening of the first component. As a result, it is prevented that the first component can bend or bend against the direction or in the direction in which the at least one bulge is formed.

Further advantages, features and details of the invention emerge from the following description of preferred exemplary embodiments and with reference to the drawings. The features mentioned above in the description and

Combinations of features and the features and combinations of features mentioned below in the description of the figures and / or shown on their own in the figures are not only in the respectively specified combination, but also in others

Combinations or can be used alone without departing from the scope of the invention.

Show:

Fig. 1 shows a section of a battery in which the arrester of battery cells

Battery are connected to each other by welding, the arresters of different battery cells that are welded to one another are furthermore welded to a cell connector of the battery;

Fig. 2 shows the problem of the occurrence of a gap between components of the

Battery such as between the arresters or between the cell connector and one of the arresters;

3 schematically shows the provision of a bulge formed as a bead in a first, upper component and the associated bridging of the gap before two components are welded together;

4 shows the stiffening effect of such a bead, which prevents bending of the upper component in the vertical direction;

5 shows the two components to be welded to one another in a condition spaced from one another and in a mutually adjacent state; and

Fig. 6 shows a variant of the welded connection, in which the upper or first

Component is brought into contact with a second component in a two-dimensional contact area, with which the first component having a plurality of bulges is to be welded, with the

Formation of several weld seams can be provided in the contact area.

With regard to the facts explained with reference to FIGS. 1 and 2, reference is made to the introductory part of the present description.

In a left illustration in FIG. 3, a first component 34 is shown, which can be, for example, the cell connector 24 shown in FIG. 1 or one of the arresters 14, 16 of the respective battery cell 12. Furthermore, a second component 36 is shown in FIG. 3, which can be a further one of the two arresters 14, 16.

For example, the first component 34 in the form of the cell connector 24 can be welded to the first arrester 14 and / or to the second arrester 16 which the second component 36 is then provided. Furthermore, the first component 34 can be designed as one of the arresters 14, 16, which is then connected to the other arrester 14, 16, in which case the second component 36 is provided by the other arrester 14, 16. The first component 34 can also be referred to as a top plate because it is arranged above the second component 36.

By forming at least one bulge 38 in the first component 34, which is shaped towards the second component 36, the gap 30 between the two components 34, 36 can be bridged during clamping. This is because the deformation of the bulge 38, which is configured as a bead, for example, causes the bead to be compressed during tensioning. If a force F is applied to the first component 34, which is illustrated in FIG. 3 by force arrows 40, the bulge 38 becomes

compressed and so the gap 30 bridged. The bead respectively

The bulge 38 is therefore flexible with regard to the size of the gap 30.

In the illustration shown in the center of FIG. 3, the gap 30 is comparatively large.

In contrast, the gap 30 is smaller in the illustration shown on the right in FIG. 3. The illustration shown on the right in FIG. 3 also indicates how the weld seam 20 is formed by means of the laser beam 32 in order to connect the two components 34, 36 to one another in an electrically conductive manner.

In a representation on the left in FIG. 4, the case is illustrated in which the

Upper plate is bent or bulged in the form of cell connector 24 (see FIG. 2) in the vertical direction (z direction). This also ensures that the cell connector 24, as an example of the first component 34, does not lie flat against the second component 36, for example in the form of the arrester 14 (see FIG. 2). This can happen if the components 34, 36 are essentially flat, that is, if the first component 34 does not have the at least one bulge 38.

According to the illustration on the right in FIG. 4, the bulge 38 or bead formed in the first component 34 ensures that the first component 34 is more rigidly stiffened. This significantly reduces the risk of the first component 34 bending in the vertical direction (z direction). The bulge 38 or bead is shown in the illustration on the right in FIG. 4 in a side view and not in cross section as in FIG. 3.

5, advantageous dimensions of the bulge 38 are to be illustrated in relation to other parameters of the first component 34 or the gap 30 become. It can thus be provided that with a thickness to of the first component 34 for a height hi <of the bulge 38, the relationship 0.001 ^* to s hi <s 1000 ^* to applies. The

Corresponding parameters of the first component 34 in the form of the thickness to and the height Iΐk are indicated in the illustration on the left in FIG.

According to the illustration on the right in FIG. 5, it is preferably provided that the height Iΐk of the respective bulge 38 formed in the first component 34, in particular by embossing, is greater than a height hs of the gap 30. In other words, that in the first component 34 should preferably introduced contour respectively

Bulge 38 have a height Iΐk which is greater than the existing gap 30 between the components 34, 36.

The bulge 38 can have many suitable geometries. It can thus be provided that at least one of the bulges 38 is designed essentially as a linear bead, as is shown schematically and by way of example in FIGS. 3 to 5.

Additionally or alternatively, at least one of the bulges 38 can be designed in a cross-shaped and / or circular shape in a plan view. However, other suitable shapes are also conceivable.

In the illustration on the left in FIG. 6, a further possibility of connecting the first component 34 to the second component 36 is shown schematically. Here, the first component 34 has a flat contact area 42, in which the first component 34 is connected to the second component 36 by welding.

In this variant, the first component 34 has in the contact area 42 a plurality of bulges 38 which are arranged next to one another but are not shown in detail in FIG. 6 and which are shaped towards the second component 36. The contact area 42, which has a defined width b _K , provides a comparatively large contact width, which enables several weld seams 20 to be formed next to one another as well as welds with wider seams. Such wide seams or weld seams 20 can be achieved, for example, by a wobbling movement of the laser beam 32, also referred to as wobbling, during laser welding. The weld seams 20 arranged next to one another are shown on the right in FIG

Illustration shown. In the area of each of these weld seams 20, the first component 34 has a respective bulge 38 which can be designed in the manner of the bead shown in FIGS. 3 to 5. According to the illustration shown by way of example in FIG. 6, several, in particular three, contours or beads can be used

be provided next to one another in the contact area 42.

However, other geometric contours such as embossments or edges can also be provided in the respective upper part or upper plate, that is to say in the first component 34, in order to bridge the gap 30 as reliably as possible. By tensioning the components 34, 36 before the welding operation, these introduced contours are pressed together flexibly, so that the weld seams 20 formed can establish a particularly reliable electrically conductive connection between the components 34, 36.

With a thickness to of the first component 34 of to 0.5 millimeters for a width b _{K of} the contact area 42, the relation 0.1 * to sb _K s 25 * to preferably applies.

It has been shown to be further advantageous if, with a thickness to of the first component 34 of to = 0.5 millimeters for a width b _{K of} the contact region 42, the relationship

0.1 ^* to s bK s 25 ^* to applies.

Such widths b _{K of} the contact area 42 have proven to be particularly advantageous for the geometric optimization of the battery contact.

List of reference symbols

battery

Battery cell

Arrester

Overlap area

Weld

Overlap area

Cell connector

Overlap area

gap

laser beam

Component

bulge

Power arrow

Contact area

Claims

Daimler AG patent claims

1. Battery, in particular for a motor vehicle, with a plurality of battery cells (12) which are electrically conductively connected to one another, with components (34, 36) formed as arresters (14, 16) of a respective battery cell (12) with one another and / or at least one component (34) designed as a cell connector (24) with at least one component (36) designed as a conductor (14, 16) of one of the battery cells (12) in an overlapping area (18, 22, 26, 28) of the components (34, 36) are connected by welding,

characterized in that

a first component (34) of the interconnected components (34, 36) has a flat contact area (42) in which the first component (34) is welded to a second component (36) of the interconnected components (34, 36) is connected, wherein the first component (34) in the contact area has one or a plurality of juxtaposed bulges (38) which are shaped towards the second component (36).

2. Battery according to claim 1,

characterized in that

with a thickness to of the first component (34) of to - 0.5 millimeters for a width b _{K of} the contact area (42), the relation 0.1 ^* to ^ b _K ^ 25 ^* to applies.

3. Battery according to claim 1 or 2,

characterized in that

with a thickness to of the first component (34) of to s 0.5 millimeters for a width b _{K of} the contact area (42) the relationship to ^ b _K ^ 125 ^* to applies.

4. Battery according to one of claims 1 to 3,

characterized in that

at a thickness to of the first component (34) for a height Iΐk of a respective

Bulge (38) the relation 0.001 * to s hi <s 1000 * to applies.

5. Battery according to one of claims 1 to 4,

characterized in that

a height Iΐk of a respective bulge (38) is greater than or equal to a height hs of a gap (30) present between the first component (34) and the second component (36) adjacent to the contact area (42).

6. Battery according to one of claims 1 to 5,

characterized in that

at least one of the bulges (38) is designed as a substantially linear bead.

7. Battery according to one of claims 1 to 6,

characterized in that

at least one of the bulges (38) is cross-shaped and / or circular in a plan view.

8. Battery according to one of claims 1 to 7,

characterized in that

in the contact area (42) the first component (34) is connected to the second component (36) by one or a plurality of weld seams (20) arranged next to one another.