DE102020213244A1 - Cell arrangement for a high-voltage battery, in particular a cell pack or cell module - Google Patents

Abstract

The invention relates to a cell arrangement for a high-voltage battery, in particular a cell module or cell pack, in which a number of pouch cells (3) of identical construction are stacked one behind the other in a stacking direction (S) to form a cell stack (Z), with opposite end faces (19, 25 ) of the pouch cell (3) each have a different geometry, and for a double-sided thermal coupling of the cell stack (Z), the cell end faces (19, 25) located on a first cell stack side have a first thermally conductive material (5) in are thermally coupled to a cooling/heating system (13) and the cell end faces located on an opposite side of the cell stack are thermally coupled to the cooling/heating system (13) via a second thermally conductive material (9). According to the invention, the geometrically identical end faces (19, 25) of all pouch cells (3) are not on the same side of the cell stack of the cell arrangement, but on the opposite sides of the cell stack, each of which has a cooling/heating interface to the cooling/heating system (13 ) form.

Description

The invention relates to a cell arrangement for a high-voltage battery according to the preamble of claim 1. Such a cell arrangement can be implemented as a cell module or as a cell pack. A cell pack is an integration of individual cells in a battery housing that is detached from the module.

A generic cell arrangement for a high-voltage battery has a number of structurally identical pouch cells, which are stacked one behind the other in a stacking direction to form a cell stack. Each of the pouch cells has a cell housing with opposite narrow end faces and opposite flat side walls. In addition, the pouch cell has two opposite narrow sides, from each of which a conductor protrudes.

In the cell stack, the pouch cells are in contact with one another on their flat side walls. The opposite end faces of the pouch cells have a different geometric structure from one another: one end face is usually designed as a flat sealed seam (hereinafter also referred to as a fold edge) and the other end face as a folded seam. In a cell arrangement known from the prior art, the end faces of all pouch cells, which are geometrically identical in construction, lie on the same side of the cell stack.

The thermal coupling of pouch cells to cooling and heating surfaces poses a particular challenge due to the design principle in the area of the seams, which are located on the front sides of the pouch cells compensate for geometric differences and tolerances. In the case of a one-sided thermal coupling of the cell stack to the thermal management with cooling and/or heating function, the cell stack side is selected as the thermal interface, where the flat sealing seams of the pouch cells, which are more suitable for this purpose, are located.

However, as soon as a double-sided thermal coupling is to be implemented with this cell type, the thermal contacting for the different end faces must also be technically solved differently. Due to the asymmetrical geometries and distances, a thermal coupling with comparable heat conduction properties is difficult to implement or requires additional process steps or different material properties of the heat-conducting material. For an optimal temperature distribution, however, comparable thermal conductivity properties should be aimed for, averaged over all pouch cells on the opposite end faces.

From the WO 2010/121831 A1 a battery module is known.

The object of the invention is to provide a cell arrangement for a high-voltage battery in which double-sided thermal coupling can take place more homogeneously than in the prior art.

The object is solved by the features of claim 1. Preferred developments of the invention are disclosed in the dependent claims.

The invention relates to a cell arrangement for a high-voltage battery, in which a number of pouch cells of identical construction are stacked one behind the other in a stacking direction to form a cell stack. Each pouch cell has opposite end faces and opposite flat side walls. In the cell stack, the pouch cells are in contact with their flat side walls. The opposing end faces of the pouch cell each have a different geometry. For a double-sided thermal coupling of the cell stack, the cell end faces located on a first side of the cell stack are thermally coupled to a cooling/heating system via a first heat conducting material, while the cell end faces located on an opposite side of the cell stack are connected via a second heat conducting material in thermal coupling with the cooling/heating system.

1. 1. Die im Zellstapel gestapelten Pouch-Zellen weisen jeweils an ihrer einen Stirnseite eine Falznaht auf, die materialaufwendig sowie bauraumintensiv gestaltet ist, so dass sich eine entsprechende Wärmeleiteigenschaft einstellt. Demgegenüber weisen die Pouch-Zellen an ihrer gegenüberliegenden Stirnseite eine materialreduziert sowie bauraumreduziert gestaltete Siegelnaht (das heißt Faltkante) auf, so dass sich eine vergleichsweise unterschiedliche (typischerweise gesteigerte) Wärmeleiteigenschaft einstellt.
2. 2. Werden solche Pouch-Zellen im Zellstapel in der Stapelrichtung deckungsgleich sowie mit gleicher Orientierung hintereinander verbaut, ergibt sich folgende Problematik:
   • Insgesamt weist der Zellstapel an seiner einen (eine thermische Schnittstelle bildenden) Zellstapel-Seite und an seiner gegenüberliegenden (eine thermische Schnittstelle bildenden) Zellstapel-Seite jeweils unterschiedliche (das heißt reduzierte oder gesteigerte) Wärmeleiteigenschaften auf. Dadurch ergibt sich im Stand der Technik eine Inhomogenität in der Zellkühlung an den gegenüberliegenden Flachseitenwänden, was gegebenenfalls die Leistungsfähigkeit bzw. die Lebensdauer der Pouch-Zellen beeinflussen kann.

The invention is based on the following facts:

1. 1. The pouch cells stacked in the cell stack each have a folded seam on one end face, which is designed to be material-intensive and space-intensive, so that a corresponding heat-conducting property is established. In contrast, the pouch cells have a sealing seam (i.e. folding edge) that is designed with reduced material and space on their opposite end face, so that a comparatively different (typically increased) heat conduction property is established.
2. 2. If such pouch cells are installed in the cell stack congruently in the stacking direction and one behind the other with the same orientation, the following problem arises:
   • Overall, the cell stack has different (i.e reduced or increased) thermal conductivity properties. In the prior art, this results in an inhomogeneity in the cell cooling on the opposite flat side walls, which can possibly affect the performance or the service life of the pouch cells.

Against this background, according to the characterizing part of claim 1, the geometrically identical end faces of all pouch cells are no longer on the same cell stack side of the cell arrangement. Rather, the geometrically identical end faces of all pouch cells lie on the opposite sides of the cell stack, each of which forms a cooling/heating interface to the cooling/heating system.

In a technical implementation, the pouch cells in the cell stack can be divided into two groups. The pouch cells of the first group are positioned in a first installation position in the cell stack, while the pouch cells of the second group are positioned in a second installation position in the cell stack. In the second installation position, the pouch cells are positioned upside down compared to the first installation position, that is to say turned over by 180° about a pivot axis aligned in the stacking direction. In this way, the inhomogeneity in the heat conduction property of one side of the cell stack and the heat conduction property of the other side of the cell stack can be significantly reduced.

According to the invention, for the implementation of a double-sided cooling/heating concept for pouch cells on the flat side walls (end faces) with different geometries when installing the cell assembly, instead of a repeating identical arrangement of the cells, i.e. always the same flat side walls (end faces ), an alternating arrangement of the respective different end faces was chosen.

Since the heat conduction properties are different, this principle can also be implemented in other arrangement patterns in order to set the heat conduction properties on both cooling/heating surfaces in the cell assembly in a way that meets the requirements over all end faces.

In the case of the heat conduction mechanism, it is assumed that the different heat conduction properties on the end faces of the individual cells are compensated for by the large-area contact between the cells. In this way, a cell assembly can be implemented which, averaged over all heat conduction properties, has a heat conduction that is adapted to the needs of the respective cooling and heating surfaces.

Through an alternating arrangement of the thermally different contact surfaces of individual cells, comparable thermal conductivity properties are achieved in the cell assembly; an adjustment through different process steps or different thermally conductive materials can be avoided in this way.

In a technical implementation, the pouch cells are positioned alternately in the first installation position and in the second installation position, viewed in the stacking direction.

The invention is particularly relevant for the cell housing structure described below: The cell housing can be made from a deep-drawn, pocket-shaped foil blank in which two opposite flat side walls merge into one another at a fold edge of the same material and in one piece (i.e. without a flange connection). In the cell housing, the two flat side walls can be brought into a flange connection at their cut edges, specifically with the formation of a housing flange. The housing flange can have at least one fold seam on the front side of the housing opposite the fold edge, which seam is formed by processing the fold of the housing flange.

In the cell housing structure described above, the fold edge (compared to the opposite fold seam) has reduced material and space requirements due to production, so that a different (typically increased) thermal coupling to the heat-conducting material can be provided at the fold edge. In contrast to this, the fold seam requires a lot of material and space due to the manufacturing process, so that there is a different (typically reduced) thermal coupling to the thermally conductive material at the fold seam. According to the invention, the pouch cells arranged one behind the other in the stacking direction are arranged alternately with fold edges and fold seams and vice versa, whereby heat dissipation on the cover side and heat dissipation on the bottom side from the cell stack can be homogenized.

In a technical implementation, the housing flange can be bent by approximately 90° at a first fold edge on the housing end face opposite the fold edge, specifically forming a fold leg on the housing side, which merges into an outer fold leg at the first fold edge. A free flange edge of the outer fold leg can be folded over by about 180° at a second fold edge, so that the outer fold leg is constructed in four layers in total, which requires a lot of material.

An exemplary embodiment of the invention is described below with reference to the accompanying figures.

• 1 in einer schematischen Seitenschnittansicht ein Zellmodul;
• 2 und 3 jeweils Ansichten einer in dem Zellmodul verbauten Pouch-Zelle;
• 4 eine Ansicht entsprechend der 1; und
• 5 in einer Ansicht entsprechend der 1 eine nicht von der Erfindung umfasste Vergleichsform.

Show it:

• 1 in a schematic side sectional view, a cell module;
• 2 and 3 in each case views of a pouch cell installed in the cell module;
• 4 a view according to the 1 ; and
• 5 in a view according to the 1 a comparative form not covered by the invention.

In the 1 a cell module for a high-voltage battery is shown to the extent necessary for understanding the invention. Accordingly, the cell module has a module housing 1 in which a number of identical pouch cells 3 are stacked one behind the other in a stacking direction S to form a cell stack Z. For double-sided thermal coupling, the top side of the cell stack is thermally connected to a module housing cover 7 via a heat-conducting material 5 on the cover side. In addition, the underside of the cell stack is thermally connected to a module housing base 11 via a heat-conducting material 9 on the base. Both the module housing base 11 and the module housing cover 7 are components of an indicated cooling system 13 or form the thermal interface to a separate cooling system.

The pouch cells 3 installed in the cell stack Z are all identical in design. Each of the pouch cells 3 has according to the 2 and 3 a cell housing 14 each with two opposite flat side walls 15, 17 in the stacking direction S. In the cell stack Z, the pouch cells 3 are in contact with one another with their flat side walls 15, 17. The cell housing 14 is in the 2 and 3 made from a deep-drawn, pocket-shaped foil blank, in which the two opposite flat side walls 15, 17 merge into one another at a fold edge 19 of the same material and in one piece. The two flat side walls 15, 17 are at their trimmed edges 21 (only in the 3 shown) each brought, for example, by a sealing process in flange connection, to form a housing flange 23. The housing flange 23 has in FIG 2 and 3 on the front side of the housing opposite the folding edge 19 there is a folded seam 25 which is formed by processing the housing flange 23 by folding.

How from the 3 As can be seen, the housing flange 23 is folded at the fold seam 25 by about 90° around a first fold edge 27, specifically with the formation of a fold leg 29 on the housing side, which merges into an outer fold leg 31 at the first fold edge 27. In addition, the fold seam 25 has a second fold edge 33 on which a free flange edge 35 is folded over by 180°, so that the outer fold leg 31 is constructed in four layers overall.

Within the cell housing 14 are in the 3 An anode 37 and a cathode 39 are arranged in a material layer structure, each with separators 41 arranged in between.

According to the invention, it was recognized that the material-intensive and space-intensive design of the fold seam 25 results in a correspondingly different thermal coupling to the respective heat-conducting material 5, 9 compared to the comparatively reduced material/space-reduced folded edge 19 to the respective heat-conducting material 5, 9.

Against this background are in the 1 the pouch cells 3 in the cell stack Z are not congruent and are arranged one behind the other in the stacking direction S with the same orientation. Rather are in the 1 and 2 the pouch cells 3 are positioned alternately in the stacking direction S in a first installation position E1 and in a second installation position E2. In the second installation position E2, the respective pouch cell 3 is positioned upside down compared to the first installation position E1, ie rotated by 180° about a pivot axis aligned in the stacking direction S.

In this way, according to the 4 the different heat flows Q _F , Q _S , Q _Z are balanced over the end faces of the pouch cells 3 and in the stacking direction S, resulting in a homogeneous temperature distribution overall with comparable thermal properties of the cooling surfaces in the cell stack Z. Therefore, according to the invention, the cell stack Z is more or less mirror-symmetrical with respect to the averaged heat transfer. As an alternative to the alternating arrangement shown, further optimization potential is possible by varying the sequence in order to adapt different properties of the cooling surfaces if necessary.

In the 5 a comparative form not covered by the invention is shown. Accordingly, the pouch cells 3 are arranged congruently one behind the other, viewed in the stacking direction S. The folded edges 19 of the pouch cells 3 are in the 5 all positioned on the cell stack bottom, while the fold seams 25 are all positioned on the cell stack top. This results in a strongly pronounced cover-side thermal coupling with increased heat transfer capability, while the bottom-side thermal coupling only has a reduced heat transfer capacity. Such a different thermal coupling to the module housing base 11 on the one hand and to the module housing cover 7 on the other leads to inhomogeneity in the heat dissipation from the cell stack Z, which impairs the service life and the functionality of the pouch cells 3 .

In the in the 1 until 4 In the exemplary embodiment shown, the pouch cells 3 are arranged with upright flat side walls 15, 17, while the cooling interfaces 13 on both sides are arranged horizontally in the battery housing 1. However, the invention is not limited to such an arrangement. In an alternative embodiment variant, the pouch cells 3 can in principle also be arranged rotated by 90°. In this case, the cells 3 are arranged horizontally with their flat side walls 15, 17, while the cooling interfaces 13 on both sides are arranged vertically in the module housing 1.

Reference List

1

module housing

3

pouch cells

5

lid-side heat-conducting material

6, 8

arrester

7

Module housing cover

9

bottom thermal conductive material

11

Module housing bottom

13

cooling system

14

cell case

15, 17

flat sidewalls

19

folding edge

21

crop edges

23

housing flange

25

folded seam

27

first folding edge

29

case-side fold leg

31

outer folding leg

33

second fold edge

35

free flange edge

37

anode

39

cathode

41

separator

S

stacking direction

Z

cell stack

e.g

housing vertical direction

E1, E2

installation positions

QUOTES INCLUDED IN DESCRIPTION

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

Patent Literature Cited

• WO 2010/121831 A1 [0006]

Claims (10)

Cell arrangement for a high-voltage battery, in particular a cell module or cell pack, in which a number of identical pouch cells (3) are stacked one behind the other in a stacking direction (S) to form a cell stack (Z), with opposite end faces (19, 25) of the pouch Cell (3) each have a different geometry, and for double-sided thermal coupling of the cell stack (Z), the cell end faces (19, 25) located on a first side of the cell stack are thermally coupled via a first heat-conducting material (5) to a cooling/heating system (13) and the cell end faces located on an opposite side of the cell stack are thermally coupled to the cooling/heating system (13) via a second heat-conducting material (9), characterized in that the end faces ( 19, 25) of all pouch cells (3) are not on the same cell stack side of the cell arrangement, but on the opposite cell stack Se Iten lie, each forming a cooling / heating interface to the cooling / heating system (13). cell arrangement claim 1 , characterized in that the pouch cells (3) in the cell stack (Z) are divided into two groups, of which the pouch cells (3) of the first group are positioned in a first installation position (E1) in the cell stack (Z) and the pouch cells (3) of the second group are positioned in a second installation position (E2) in the cell stack (Z), in which the pouch cells (3) are positioned at an angle of 180° compared to the first installation position (E1). cell arrangement claim 2 , characterized in that in the second installation position (E2) positioned pouch cells (3) compared to the, in the first installation position (E1) positioned pouch cells (3) in the stacking direction (S) aligned pivot axis or a pivot axis aligned transversely to the stacking direction (S) are rotated by 180°. cell arrangement claim 2 or 3 , characterized in that the respective adjacent pouch cells (3) in the stacking direction (S) are positioned alternately in the first installation position (E1) and in the second installation position (E2). Cell arrangement according to one of the preceding claims, characterized in that each pouch cell (3) has opposite flat side walls (15, 17), and that the pouch cells (3) in the cell stack (Z) with their flat side walls (15, 17) in System are, and that each pouch cell (3) has opposite narrow sides, from each of which a conductor (6, 8) protrudes. Cell arrangement according to one of the preceding claims, characterized in that of the two cell end faces a first cell end face (25) is designed to be material-intensive and space-intensive for manufacturing reasons, so that a first, in particular reduced, thermal conductivity property results, and that a second cell end face (19) is designed with reduced material and space due to production, so that a different, second, in particular increased, thermal conductivity property results. cell arrangement claim 6 , characterized in that the cell housing (14) of each pouch cell (3) is made from a deep-drawn, bag-shaped foil blank, in which the two opposite flat side walls (15, 17) are of the same material and integral with each other at a folded edge (19). go over, and that in particular the folded edge (19) is the second cell end face with the different second, in particular increased thermal conductivity property. cell arrangement claim 7 , characterized in that in the cell housing (14) the two flat side walls (15, 17) are flanged at their trimmed edges (21), to be precise with the formation of a housing flange (23), and that the housing flange (23) at the fold edge (19) has at least one fold seam (25) on the opposite housing end face, which is formed by fold processing of the housing flange (23), and that in particular the fold seam (25) is the first cell end face with the first, in particular reduced, thermal conductivity property. cell arrangement claim 8 , characterized in that the housing flange (23) is bent by about 90° at a first folded edge (27) on the end face opposite the folded edge (19), specifically with the formation of a folded leg (29) on the housing side, which at the first folded edge (27) merges into an outer folding leg (31). cell arrangement claim 9 , characterized in that a free flange edge (35) of the outer fold leg (31) is turned over by about 180° at a second fold edge (33), so that the outer fold leg (31) is constructed in four layers.

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