DE102022212886A1 - Battery system, in particular for a motor vehicle, and motor vehicle - Google Patents

Abstract

The invention relates to a battery system (10) with a plurality of battery cells (14) combined to form a cell stack, wherein the battery cells (14) each have a cell housing (16) and an electrochemical cell (18) accommodated in the cell housing (16). The cell housings (16) have an at least substantially cuboidal basic shape with opposing surface sides (20) oriented at least substantially at right angles to the stacking direction, two opposing first narrow sides (22) and two opposing second narrow sides (24). The battery cells (14) are subjected to a contact force acting in the stacking direction (X), wherein elastically compressed intermediate layers (28) are arranged between adjacent battery cells (14) by a first portion of the contact force, wherein the first portion of the contact force is transmitted through the intermediate layers (28) between adjacent battery cells (14). Spacer elements (30) are arranged between adjacent battery cells (14), wherein a second portion of the contact pressure is transmitted between adjacent battery cells (14) via the spacer elements (30). The battery system (10) is designed such that the second portion of the contact pressure is transmitted at least predominantly via the housing areas forming the first narrow sides (22) of the respective cell housing (16).

Description

The invention relates to a battery system, in particular for supplying an electric drive of a motor vehicle with electrical energy, according to the preamble of claim 1, and to a motor vehicle with such a battery system.

Battery systems of the type in question are used in particular to supply electrical energy to electrical consumers that require high electrical power and/or high capacity. A common application is where the electrical consumer is a drive system of an electrically powered motor vehicle.

In order to achieve the required high performance and/or capacity, battery systems of the type in question typically have a plurality of battery cells. One possibility for arranging the battery cells in the battery system is to combine a plurality of battery cells into a cell stack.

A change in the cell volume can occur during the charging and discharging processes. It is also possible that the cell volume increases over the course of the operating period. Experts refer to this as the "swelling" of the battery cells.

In addition, it is generally advantageous to apply a mechanical compressive stress to the electrochemical cells, which counteracts the swelling of the cells. To achieve this, the battery cells combined to form a cell stack can be subjected to a contact force acting in the direction of the stack.

To ensure that the contact forces acting between the battery cells in a cell stack do not increase disproportionately when the interior of the cells swells, it has proven useful to arrange intermediate layers made of an elastically compressible intermediate layer material between the battery cells in a cell stack. The elastic intermediate layers can act as a type of spring-loaded force buffer between the battery cells and thus prevent the compressive forces acting in a cell stack from increasing disproportionately if the mechanical tension of the cells in the cell stack does not give in to the increasing compressive forces in the cell stack.

However, component tolerances can lead to displacements along the stacking direction in a clamped cell stack. In addition, the dependence of the force with which the stack is clamped on the elastic compression of the intermediate layers means that the clamping force is highly dependent on the resulting stack length and the resulting stack length on the clamping force.

In practice, this leads to the need for tolerance compensation measures in the area of the electrical contact of the battery cells. However, it would be desirable to be able to dispense with such measures.

One way to counteract this is to provide spacer elements between the battery cells so that a portion of the force with which the cell stack is braced is transferred via the spacer elements between neighboring battery cells. This should lead to defined distances between neighboring battery cells, but in previous solutions the force is transferred via the battery cells via areas of the battery cells with very different mechanical properties. This makes it more difficult to achieve an advantageous contact force distribution on intermediate layers and spacer elements.

The object of the present invention is therefore to demonstrate a battery system and a motor vehicle with such a battery system, in which properties with regard to the defined cell positions in the stacking direction within a cell stack and the defined force distribution between spacer elements and intermediate layers are improved.

The object is achieved by a battery system and a motor vehicle having the features of the independent claims. The features of the dependent claims relate to advantageous embodiments.

The battery system has a plurality of battery cells combined to form a cell stack. The battery cells can in particular be so-called prismatic cells. The battery system can have a plurality of cell stacks of the type described below.

The battery cells each have a cell housing and an electrochemical cell housed in the cell housing. The electrochemical cell is in particular a lithium-ion cell. Alternatively, however, it can also be another type of rechargeable electrochemical cell.

The cell housings have a, at least essentially, cuboidal basic shape. The cell housings each have two opposite surface sides. The surfaces sides are oriented, at least substantially, at right angles to the stacking direction. Furthermore, the cell housings each have two opposing first narrow sides and two opposing second narrow sides. The first narrow sides and the second narrow sides are in particular, at least substantially, oriented parallel to the stacking direction. Battery cells designed in this way can be combined particularly well to form cell stacks. The individual battery cells in particular have a thickness direction oriented parallel to the stacking direction, in which the spatial extent of the respective battery cell is significantly smaller than in the extension directions of the respective battery cell oriented perpendicular to the narrow sides of the respective battery cell.

The battery cells are subjected to a contact pressure acting in the direction of the stack. The contact pressure can be generated in particular by the mechanical tension of pressure elements that are arranged at the ends of the cell stack and transfer the contact pressure to the cell stack.

Intermediate layers are arranged between neighboring cells. The intermediate layers are elastically compressed by a first portion of the contact force. The first portion of the contact force is transferred through the intermediate layers between neighboring battery cells. The intermediate layers can contain an aerogel as a component. Aerogels have proven to be particularly suitable for producing intermediate layers that are particularly thermally well-insulated and suitable in terms of flexibility with regard to cell swelling.

Spacer elements are arranged between adjacent battery cells. A second portion of the contact force is transferred between adjacent battery cells via the spacer elements. The contact force transferred by the spacer elements is introduced into the battery cells in particular via the facing surfaces of adjacent battery cells. The local distribution of the force introduction into the respective cell housings is determined in particular by the arrangement of the contact surfaces of the spacer elements lying on the surfaces.

The object is achieved in particular in that the battery system is designed in such a way that the second portion of the contact pressure is transmitted at least predominantly via the housing areas forming the first narrow sides of the respective cell housing. A predominantly portion is to be understood in particular as a portion of at least 50%, in particular at least 80%, of the second portion of the contact pressure transmitted by the spacer elements. It has been found that, due to the typically prevailing structure of such battery cells, certain areas of the cell housing are better suited to transmitting forces than others. These are typically areas of the cell housing that form certain narrow sides, in particular narrow sides that lie opposite one another. The present invention takes advantage of this circumstance to enable advantageous support of the second portion of the contact pressure, which is transmitted by the spacer elements, by the cell housing.

In particular, this enables the at least extensive decoupling of the transmission of this second portion of the contact force from the transmission of the first portion of the contact force, which takes place through the intermediate elements and is to be transmitted, if possible, through the electrochemical cells arranged within the cell housings in order to counteract swelling.

This means that the cell stack can be clamped with a relatively high contact force without the contact force acting on the intermediate layers and the electrochemical cells becoming too high, since after the intermediate elements have been compressed to a certain level, the spacer elements absorb the contact force and transfer it to housing areas that are particularly suitable for this purpose. By further increasing the contact force, the intermediate elements are not compressed significantly more, and the first part of the contact force transmitted by the respective intermediate elements is therefore not increased significantly. At the same time, the spacer elements and their support on the cell housings specify a defined distance between adjacent battery cells. This results in a precisely defined position of the respective battery cells along the stack direction that is not influenced, or at least to a significantly lesser extent, by the swelling that occurs during further operation.

The cell housings can each have a greater wall thickness on a first narrow side, in particular on both first narrow sides, than on their other surface sides and narrow sides. The greater wall thicknesses result in higher mechanical load capacities in the area of the first narrow sides. In connection with the transmission of the majority of the second part of the contact force via the housing areas forming the first narrow sides, this results in an advantageous absorption of the forces in areas of the cell housing with greater wall thicknesses.

The cell housings can each have a cell closure plate, in particular a welded-in one, on a first narrow side, in particular on both first narrow sides. Such cell housing designs, in which cell closure plates are present, in particular welded-in, on one narrow side or on two opposite narrow sides, can have a higher mechanical load capacity in the area of the cell closure plates than in other areas of the cell housing. It can therefore be advantageous if the second part of the contact pressure transmitted by the spacer elements is transmitted, at least for the most part, by cell closure plates.

The spacer elements can be arranged on the first narrow sides of the cell housing and have spacer regions for transmitting the second part of the contact force, which extend from the first narrow side between the surface sides of adjacent battery cells. Such an arrangement of the spacer elements on the narrow sides makes it possible, in particular in an advantageous manner, to design the spacer elements so that they fulfill additional functions. In addition, the fastening of the spacer elements to the battery cells on the first narrow side can be simplified, in particular by designing the spacer elements so that they encompass the edges of the battery cell.

Alternatively and/or additionally, however, spacer elements, for example in strip form, can only be attached to the surface sides, for example glued to them. In other words, such spacer elements can be reduced to the spacer areas arranged between the surface sides of adjacent battery cells.

The spacer elements can each have at least two spacer regions, one of which extends between the surface sides of neighboring battery cells in the region of each of the two surface sides of the battery cell, on the narrow side of which the respective spacer element is arranged. Spacer elements designed in this way make it possible to provide spacer regions on both surface sides of the respective battery cell in a one-piece design. The spacer regions are connected to one another in particular by a connecting region arranged on the first narrow side of the respective battery cell and extend in particular from this connecting region between the surface sides of neighboring battery cells.

The spacer elements can be made in one piece. In particular, they can be injection-molded components. These can be manufactured in large quantities at low cost and with low tolerances. The spacer elements can in particular be made of a plastic. In particular, it can be a plastic that has low flow properties under pressure. Alternatively and/or additionally, it can be a plastic that is hardened using light, in particular UV light.

In particular, the spacer elements can be injection-molded onto the battery cells. This can be done particularly advantageously in conjunction with a plastic that is cured using light or UV light, as the pressures and temperatures when injection-molded onto the battery cell can then be reduced to a level that is tolerable for the battery cell. Injection-molded allows tolerances in the battery cells to be compensated, particularly in the stacking direction.

Alternatively and/or additionally, the spacer elements can be glued to the battery cell. The adhesive can in particular provide tolerance compensation. In this case, tolerance compensation in the direction of the stacking direction can be achieved in particular by adhesive films whose thickness is oriented parallel to the stacking direction. Tolerances in the dimensions of the battery cells can be compensated for by the thickness of the adhesive film.

The spacer elements can be designed as end caps. Spacer elements designed in this way can be plugged onto the battery cells on the respective narrow side. This makes it easy to install the spacer elements. Alternatively and/or additionally, the spacer elements can be molded onto the battery cells on the respective narrow side.

The spacer elements of adjacent battery cells and/or the spacer regions of the spacer elements of adjacent battery cells can support one another in the stacking direction. The spacer elements or the spacer regions of the spacer elements support one another in particular in such a way that the thicknesses of the spacer elements and/or spacer regions supporting one another add up. In this way, for example, symmetrical designs of the spacer elements can be realized and thus a comparatively universal usability of identical parts at the different positions in the cell stack can be improved.

The spacer elements and/or the spacer regions of the spacer elements can extend in strip form over regions of the surface sides that border on the first narrow sides. These zones of the surface sides are typically located in the region of the cell housing where particularly resilient regions of the cell housing that form the first narrow sides border on or merge into those regions of the cell housing that form the surface sides. A strip-shaped extension of the spacer elements or spacer regions over these regions of the surface sides leads to a force being introduced at the resulting contact surface, which is also strip-shaped, between the surface side and the spacer region or spacer element, which leads to a direct transfer of the forces into those particularly resilient regions of the cell housing on the first narrow side.

The spacer elements or a part of the spacer elements can each have an area which is adapted in terms of its geometry to a manipulator used in assembling the battery system. Such an area can, for example, be an engagement area for a gripper which is used as a manipulator in assembling the battery system.

Alternatively and/or additionally, the spacer elements or a part of the spacer elements can each have a region that is adapted to a cell contact unit in terms of its geometry. In this way, the spacer elements can be used as a carrier for such a cell contact unit or a cell contact unit can be attached to the respective battery cell by means of the spacer elements.

Alternatively and/or additionally, the spacer elements or a part of the spacer elements can each have a region which is adapted in terms of its geometry to a complementary geometry of a region of a spacer element of an adjacent battery cell. In this way, in particular, a spatial alignment of the adjacent battery cells to one another can be improved or ensured by the spacer elements.

Alternatively and/or additionally, the spacer elements or a part of the spacer elements can each have an area that is adapted to a sensor. The sensor can be a temperature sensor, for example. In this way, the spacer elements can be used as a carrier for a sensor or a sensor can be attached to the respective battery cell using the spacer elements.

Alternatively and/or additionally, the spacer elements or a part of the spacer elements can each have an area that is adapted to a pole of a battery cell. This can in particular make it easier to contact the pole. The area can be an opening, for example. For example, the pole can pass through the opening and be contacted in a simple manner.

Alternatively and/or additionally, the spacer elements or a part of the spacer elements can each have an area that is adapted to another component of the battery system. In this way, the spacer elements can be used as a carrier for such another component or such another component can be attached to the respective battery cell by means of the spacer elements. Alternatively and/or additionally, the attachment of the respective battery cell to another component of the battery system is also conceivable.

Alternatively and/or additionally, the spacer elements or a part of the spacer elements can each have an area that is adapted to reference points of a reference point system. The adapted area can be designed in particular as a surface, hole, slot or pin. The spacer element can therefore be used as a reference for the positioning of battery cells, cell stacks and/or the battery system.

The invention further relates to a motor vehicle with a battery system as described above. The motor vehicle has an electric drive. The electric drive is supplied with electrical energy by the battery system.

• 1 eine schematische perspektivische Darstellung einer beispielhaften Batteriezelle mit Abstandshalterelementen an den ersten Schmalseiten,
• 2 und 3 Darstellungen der Abstandshalterelemente aus 1,
• 4 eine Schnittdarstellung durch eine Batteriezelle entsprechend der 1 im Bereich einer ersten Schmalseite,
• 5 eine schematische perspektivische Darstellung eines Zellstapels zu dem eine Mehrzahl Batteriezellen entsprechend der 1 zusammengefasst ist,
• 6 eine Draufsicht auf einen Bereich des Zellstapels aus 5.

The invention is described below with reference to 1 to 6 schematically explained in more detail. Shown are:

• 1 a schematic perspective view of an exemplary battery cell with spacer elements on the first narrow sides,
• 2 and 3 Representations of the spacer elements from 1 ,
• 4 a cross-sectional view of a battery cell according to the 1 in the area of a first narrow side,
• 5 a schematic perspective view of a cell stack to which a plurality Battery cells according to the 1 is summarized,
• 6 a top view of a section of the cell stack 5 .

The battery system 10 has a plurality of battery cells 14 combined to form a cell stack 12. The battery cells 14 can have cell housings 16.

The battery cells 14 each have a cell housing 16. Furthermore, the battery cells 14 each have an electrochemical cell 18 accommodated in the cell housing 16. This is particularly evident in the sectional view in 4 to recognize.

The cell housings 16 have, as for example in 1 can be seen, an at least substantially cuboid-shaped basic shape with mutually opposite surface sides 20 oriented at least substantially vertically, at least substantially at right angles to the stacking direction X, two mutually opposite first narrow sides 22 and two mutually opposite second narrow sides 24.

The battery cells 14 are subjected to a contact pressure acting in the stacking direction X. This can be done, for example, by means of pressure elements 26, as in the example shown.

Intermediate layers 28 are arranged between adjacent battery cells 14. The intermediate layers 28 are elastically compressed by a first portion of the contact force. The first portion of the contact force is transmitted through the intermediate layers 28 between adjacent battery cells 14.

The intermediate layers 28 are particularly in the 6 shown.

A second part of the contact pressure is transmitted via spacer elements 30 between adjacent battery cells 14. The battery system 10 is designed such that the second part of the contact pressure is transmitted at least predominantly via the housing areas forming the first narrow sides 22 of the respective cell housing 16.

As in the example shown, the cell housings 16 can each have a greater wall thickness on both first narrow sides 22 than on their other surface sides 20 and narrow sides 24. For this purpose, the cell housings 16 can have, in particular, welded cell closure plates 32 on their first two narrow sides 22. This is particularly the case in the 4 to recognize.

The spacer elements 30 can be arranged on the first narrow sides 22 of the cell housings 16, as in the example shown. To transmit the contact pressure, the spacer elements 30 can have spacer regions 34, as in the example shown, which extend from the first narrow side 22 between the surface sides 20 of adjacent battery cells 14. This is particularly the case in the 4 and 6 As in the example shown, the spacer elements 30 can each have two spacer areas 34, one of which extends in the area of each of the two surface sides 20 of the battery cell 14, on the narrow side 22 of which the respective spacer element 30 is arranged, between the surface sides 20 of adjacent battery cells 14. This is also particularly evident in the 4 and 6 As in the example shown, the spacer elements 30 can in this context each have a connecting region 36 connecting the spacer elements 34.

As in the example shown, the spacer regions 34 of the spacer elements 30 of adjacent battery cells 14 can support one another in the stacking direction X. The thicknesses of the spacer regions 34 supporting one another can be added together, as in the example shown.

As in the example shown, the spacer areas 34 of the spacer elements 30 can extend in strip form over areas of the surface sides 20 adjacent to the first narrow sides 22. This is particularly the case in the 1 and 4 to recognize. Also in 3 the strip-shaped surfaces of the spacer regions 34 adjacent to the surface sides 20 can be seen.

As in the example shown, the spacer elements 30 can each have a region 38 which is adapted in terms of its geometry to a pole 40 of the respective battery cell 14.

As in the example shown, the region 38 can be designed as an opening, in particular in a connecting region 36 of the respective spacer element 30. As in the example shown, the poles 40 can pass through the adapted regions 38 of the spacer elements 30 designed as openings.

As in the example shown, the spacer elements 30 can be designed as end caps that are placed on the battery cells 14 at the respective Narrow sides 22 are plugged on and/or molded onto the battery cells 14 on the respective narrow side 22, 24. In this way, the spacer elements 30 can be mounted in a simple manner.

The features of the invention disclosed in the present description, in the drawings and in the claims can be essential for the realization of the invention in its various embodiments both individually and in any combination. The invention can be varied within the scope of the claims and taking into account the knowledge of the competent person skilled in the art.

List of reference symbols

10

Battery system

12

Cell stack

14

Battery cells

16

Cell housing

18

electrochemical cell

20

Surface pages

22

first narrow sides

24

second narrow sides

26

Pressure element

28

Intermediate layers

30

Spacer element

32

Cell closure plates

34

Social distancing areas

36

Connection area

38

Area, adjusted

40

Pole

X

Stacking direction

Y

Direction

Z

Direction

Claims (10)

Battery system (10) with a plurality of battery cells (14) combined to form a cell stack, wherein the battery cells (14) each have a cell housing (16) and an electrochemical cell (18) accommodated in the cell housing (16), wherein the cell housings (16) have an at least substantially cuboidal basic shape with mutually opposite surface sides (20) oriented at least substantially at right angles to the stacking direction, two mutually opposite first narrow sides (22) and two mutually opposite second narrow sides (24), wherein the battery cells (14) are subjected to a contact force acting in the stacking direction (X), wherein elastically compressed intermediate layers (28) are arranged between adjacent battery cells (14) by a first portion of the contact force, wherein the first portion of the contact force is transmitted through the intermediate layers (28) between adjacent battery cells (14), wherein spacer elements (30) are arranged between adjacent battery cells (14), wherein Spacer elements (30) a second portion of the contact pressure is transmitted between adjacent battery cells (14), characterized in that the battery system (10) is designed such that the second portion of the contact pressure is transmitted at least predominantly via housing areas forming the first narrow sides (22) of the respective cell housing (16). Battery system (10) according to Claim 1 , characterized in that the cell housings (16) each have a greater wall thickness on a first narrow side (22), in particular on both first narrow sides (22), than on their other surface sides (20) and narrow sides (24). Battery system (10) according to one of the preceding claims, characterized in that the cell housings (16) each have a cell closure plate (32), in particular a welded-in one, on a first narrow side (22), in particular on both first narrow sides (22). Battery system (10) according to one of the preceding claims, characterized in that the spacer elements (30) are arranged on the first narrow sides (20) of the cell housings (16) and have spacer regions (34) for transmitting the second portion of the contact force, which extend from the first narrow side (22) between the surface sides (20) of adjacent battery cells (14). Battery system (10) according to Claim 4 , characterized in that the spacer elements (30) each have at least two spacer regions (34), one of which extends in the region of each of the two surface sides (20) of the battery cell (14), on the narrow side (22, 24) of which the respective spacer element (30) is arranged, between the surface sides (20) of adjacent battery cells (14). Battery system (10) according to one of the preceding claims, characterized in that the spacer elements (30) of adjacent battery cells (14) and/or the spacer region surface (34) of the spacer elements (30) of adjacent battery cells (14) are supported on one another in the stacking direction (X), in particular such that the thicknesses of the spacer elements (30) and/or spacer regions (34) supported on one another add up. Battery system (10) according to one of the preceding claims, characterized in that the spacer elements (30) and/or the spacer regions (34) of the spacer elements (30) extend in strip form over regions of the surface sides (20) adjacent to first narrow sides (22). Battery system (10) according to one of the preceding claims, characterized in that the spacer elements (30) or a part of the spacer elements (30) each have a region (38) which is adapted in terms of its geometry to: • a manipulator used in the assembly of the battery system (10), • reference points of a reference point system, • a cell contacting unit, • a complementary geometry of a region of a spacer element (30) of an adjacent battery cell (14), • a sensor, in particular a temperature sensor, • a pole (40) of a battery cell (14) and/or • another component of the battery system (10). Battery system (10) according to one of the preceding claims, characterized in that the spacer elements (30) are designed as end caps which are in particular plugged onto the battery cells (14) on the respective narrow side (22, 24) and/or are injection-molded onto the battery cells (14) on the respective narrow side (22, 24). Motor vehicle with a battery system (10) according to one of the preceding claims and an electric drive, wherein the electric drive is supplied with electrical energy by the battery system (10).

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