DE102021112599A1 - Method for manufacturing a battery cell, forming device and battery cell - Google Patents

Abstract

The invention relates to a method and a device for producing a battery cell (1), at least comprising a housing (2) and arranged therein at least one stack (3) of electrode foils (4) arranged one on top of the other, the housing (2) being made of a foil material (5 ) is produced by folding the film material (5).

Description

The invention relates to a battery cell and a method and a device for producing a battery cell.

The battery cell comprises a gas-tight housing and at least one stack of electrode foils arranged one on top of the other arranged therein. The housing is made of foil material by folding the foil material.

A battery cell is an electricity storage device that B. is used in a motor vehicle for storing electrical energy. In particular, z. B. a motor vehicle has an electric machine for driving the motor vehicle, wherein the electric machine can be driven by the electrical energy stored in the battery cell. In a battery cell, electrode foils, ie anodes and cathodes, are arranged stacked on top of one another, with different electrode foils being arranged separated from one another by separator foils or a separator material. The electrode foils are arranged in an electrolyte. There are e.g. B. battery cells with liquid or solid electrolytes (solid battery) are known.

A battery module includes, in particular, a plurality of battery cells which are electrically connected to one another in series or in parallel and are arranged in a module housing. Individual battery modules can also be electrically connected to one another in series or in parallel. A battery includes a battery module or a plurality of battery modules.

Battery cells can be designed as so-called pouch cells (or pocket cells). The pouch cells include a composite material referred to as a pouch film as the film material for the housing. The composite material is a composite material, in particular comprising aluminum and plastic. The housing can be formed by a plurality of film materials which are arranged one on top of the other and form a housing part which encloses the stack and an edge region which protrudes outwards from the housing part in the radial direction. The housing can also be formed from a single foil material, with the housing being formed by folding the foil material. In this case, no sealing seam for sealing the edge area is required at least on one side surface of the cell housing. In the (remaining) edge areas, the film materials lying on top of one another are connected to one another in a gas-tight manner, in particular via a sealed seam.

There may be a requirement to connect a battery cell to a cooling element or a cooling surface for cooling. Cooling cannot take place via the side surfaces of the cell housing, where the conductors are led out of the cell housing. The long, narrow side surfaces of pouch cells are regularly connected to cooling surfaces. The connection usually only takes place via the side surface on which the foil material was folded. There is a sealed seam on the other side surface. The heat conduction towards the cooling surface is impaired on this side surface as a result of the sealing seam.

In the case of housings that are formed from a foil material by folding the foil material, cracks often occur in the area of the fold during cell respiration during operation of the battery cell. Furthermore, the ability of the film material to be deep-drawn is impaired, at least in the areas of the film material that are adjacent to the fold line.

From the WO 2012/022448 A1 an electrochemical cell is known whose casing/case is made of a single piece of casing which is folded and sealed. This eliminates the need for a sealed seam on one narrow side of the cell.

From the EP 3 611 775 A1 a battery cell with a cover folded from a flat blank is known.

From the DE 10 2018 104 554 A1 a battery cell is known whose cell casing consists of a foil material that is folded along a fold line. At the ends of the fold line, a folding aid designed as a depression or material allowance is provided in each case laterally adjacent to the fold line, by means of which an overhang of the film material caused by the folding is to be counteracted.

The object of the present invention is to at least partially solve the problems cited with reference to the prior art. In particular, a method for producing a battery cell is to be proposed, by which a housing of the battery cell is produced from a single film material. The deep-drawing ability of the film material is to be improved and the formation of cracks during operation of the battery cell is to be prevented

A method with the features according to patent claim 1 contributes to the solution of these tasks. Advantageous developments are the subject matter of the dependent patent claims. The features listed individually in the claims can be combined with one another in a technologically sensible manner and can be explained by explanatory facts from the description and/or details from the Figures are supplemented, with further variants of the invention being shown.

1. a) Bereitstellen einer zumindest zweiteiligen Matrize mit zumindest einer ersten Ausnehmung in einem ersten Matrizenteil und einer beabstandet zur ersten Ausnehmung angeordneten zweiten Ausnehmung in einem zweiten Matrizenteil, der gegenüber dem ersten Matrizenteil klappbar ausgeführt ist;
2. b) (Bereitstellen mindestens eines Folienmaterials und) Anordnen mindestens eines Folienmaterials auf der in einer Ausgangsposition vorliegenden Matrize und über den Ausnehmungen in einem Flächenabschnitt;
3. c) erstes Umformen des Folienmaterials entlang einer gedachten Faltlinie mit einem Vorformstempel oder einer Vorformeinrichtung in einem Bereich, wobei die Faltlinie zwischen den Ausnehmungen verläuft; wobei der umgeformte Bereich des Folienmaterials ein Materialreservoir für die nachfolgende zweite Umformung des Folienmaterials bildet;
4. d) (Bereitstellen eines Stempelwerkzeugs mit zu den Ausnehmungen korrespondierenden Stempelgeometrien und) zweites Umformen des Folienmaterials im Bereich der Ausnehmungen mit einem Stempelwerkzeug mit zu den Ausnehmungen korrespondierenden Stempelgeometrien, wobei während der zweiten Umformung das im Materialreservoir vorliegende Folienmaterial hin zu den Ausnehmungen verschoben wird;
5. e) Anordnen des mindestens einen Stapels in dem Folienmaterial und Verschließen des Folienmaterials in einem Randbereich zur Ausbildung des Gehäuses und zur Fertigstellung der Batteriezelle.

A method for producing a battery cell is proposed. The battery cell comprises at least one housing and at least one stack of electrode foils arranged one on top of the other arranged therein. The housing is made of foil material by folding the foil material. The procedure comprises at least the following steps:

1. a) providing an at least two-part die with at least one first recess in a first die part and a second recess, spaced apart from the first recess, in a second die part which is designed to be foldable relative to the first die part;
2. b) (providing at least one foil material and) arranging at least one foil material on the die present in a starting position and over the recesses in a surface section;
3. c) first forming of the film material along an imaginary fold line with a preforming die or a preforming device in one area, the fold line running between the recesses; wherein the deformed area of the foil material forms a material reservoir for the subsequent second deformation of the foil material;
4. d) (providing a stamping tool with stamping geometries corresponding to the recesses and) second forming of the foil material in the area of the recesses with a stamping tool with stamping geometries corresponding to the recesses, with the foil material present in the material reservoir being displaced towards the recesses during the second forming;
5. e) arranging the at least one stack in the film material and sealing the film material in an edge area to form the housing and to complete the battery cell.

The above (non-exhaustive) division of the method steps into a) to e) is primarily intended to serve only as a distinction and does not impose any order and/or dependency. The frequency of the process steps can also vary. It is also possible for method steps to at least partially overlap one another in terms of time. In particular, steps a) to e) are carried out in the order listed.

In a battery cell, in particular, electrode foils, ie anodes and cathodes, are stacked one on top of the other, with different electrode foils being arranged separated from one another by separator foils or a separator material. The electrode foils are arranged in an electrolyte. There are e.g. B. battery cells with liquid or solid electrolytes (solid battery) are known. The battery cell is in particular a lithium-ion battery cell. The battery cell is electrically contacted in particular via conductors which make electrical contact with the electrode foils inside the battery cell and extend outwards via the housing, in particular via the edge regions which are formed by the foil materials folded on top of one another according to step e).

In particular, the housing is formed only by a one-piece foil material. In the context of the method, the film material is folded along a fold line which, in particular, only extends along a straight line. As a result of the folding, the housing has an edge region on a side surface of the housing that is formed by the continuous foil material and that does not require any further sealing measures. In the case of a (substantially) cuboid housing, the edge regions which extend along three side surfaces and are formed by the film material placed on top of one another as a result of the folding are sealed in a gas-tight manner, in particular by sealing seams.

The foil material is in particular a pouch foil, preferably a composite material designed as a composite material, in particular comprising aluminum and plastic.

According to step a), an at least two-part die is provided with at least one first recess in a first die part and a second recess arranged at a distance from the first recess in a second die part, which is designed to be foldable relative to the first die part. The housing halves, in particular, are formed from the film material with the recesses and are arranged one on top of the other by folding the film material to form the housing.

According to step b), in particular at least one, preferably exactly one, film material is provided and the film material is arranged on the matrix present in a starting position and over the recesses in a surface section. The at least one film material is in particular designed to be flat. In particular, the film material is provided as an endless material.

In particular, the foil material extends beyond this surface section at least along an edge of the surface section running parallel to the imaginary fold line.

The die is arranged in particular on one side of the film material.

According to step c), in particular, a first reshaping of the foil material takes place along an imaginary fold line with a preforming punch and/or a preforming device in an area, with the fold line running between the recesses. The deformed area of the foil material forms a material reservoir for the subsequent second deformation of the foil material.

The folding line that is only imaginary (planned, predetermined) at this point in time of the method and only realized later by folding extends in particular exclusively along a straight line.

The preforming punch is formed in particular between the recesses in the die and is designed to be movable with respect to the die. An area encompassing the fold line is formed with the preforming die. In particular, the first forming takes place without stretching the foil material, ie without reducing the material thickness of the foil material. In particular, a material thickness of the foil material in the formed area is reduced by at most 5%, preferably by at most 2%, particularly preferably by at most 1%, as a result of the first forming. In particular, in the course of the first reshaping, film material is fed from outside the surface section into this surface section.

In particular, as a result of the first reshaping, an extension of the film material, which is in particular previously flat, located between the recesses is lengthened by at least 10%, preferably by at least 20%, particularly preferably by at least 30%.

In particular, a sheet metal holder is arranged on the other side of the foil material, ie opposite the die, by means of which the foil material can be fixed in a predetermined position on the die. However, the blank holder makes it possible, in particular, for the film material to be fed into the surface section during the first forming operation. In particular, the foil material is only fed into the surface section from one direction, e.g. B. from an outside of the surface portion available device for the film material, z. B. a roll on which the film material is wound as a continuous material. This allows other areas of the foil material to be fixed by the sheet metal holder and the die.

The preforming stamp deforms the foil material in particular towards the sheet metal holder.

The first forming can be determined in advance via a simulation and is controlled via the blank holder and the preforming punch.

As an alternative to the design with the preforming die, the first forming can be carried out using air pressure or electromagnetic pulse technology.

According to step d), in particular, a stamping tool is provided with stamping geometries that correspond to the recesses. A second reshaping of the film material in the region of the recesses takes place with the stamping tool, with the film material present in the material reservoir being displaced towards the recesses during the second reshaping.

In particular, the stamping tool is arranged on the same side of the foil material as the blank holder. The foil material is formed into the die by the stamping tool.

As a result of the displacement of the film material present in the material reservoir, the ability of the film material to be deep-drawn is decisively improved. A stretching of the film material in the area of the recesses can be reduced in this way. In particular, during the second forming, the material reservoir is completely dissolved again, so that the extent of the foil material located between the recesses is returned to the state that was present immediately before the first forming.

In particular, the film material present between the recesses is stretched at the end of step d), ie when the stamping tool has reached its end position in the recesses. In particular, the stretching reduces a material thickness of the film material in the area of the fold line that is produced later by at least 0.5%, preferably by at least 1%.

In particular, heating elements are arranged along the recesses in the die, which can heat the foil material for the second forming at least in partial areas. As a result of the heating of the foil material, the deep-drawing of the foil material in the area of the lateral boundaries of the recesses can be improved and the risk of tearing of the foil material can be further reduced.

According to step e), the at least one stack is arranged in the foil material and the foil material is closed in an edge area or in all edge areas (except for the edge area formed by the fold) to form the housing and to complete the battery cell.

In particular, before step e), the stamping tool is removed from the recesses. In particular, the blank holder is also removed from the die. During step e), in particular after the at least one stack has been arranged, the film material is folded over the fold line so that the film material is placed on top of one another in the edge regions and a closed volume of the housing is formed. The stack is arranged in particular in the areas of the foil material that are formed as a result of the second forming and correspond to the recesses. As a result of the folding, these areas shaped to correspond to the recesses are in particular arranged in alignment with one another, so that a volume for accommodating at least the stack is formed by the foil material folded on top of one another.

In particular, the stack is aligned with the recess via the conductors of the electrode foils, so that one layer of the stack is fixed relative to the foil material. The alignment can be done using a positioning device, e.g. B. via bar elements, which are arranged in the matrix and between which the conductors are arranged during the arrangement of the stack in the recess.

In particular, during step c) a quantity of film material used for the material reservoir is fed at least partially from outside the surface section into the surface section. In particular, at least 95% of the amount of film material used for the material reservoir is fed from outside the surface section, preferably at least 99%, particularly preferably at least 99.9%. This allows the foil material to be stretched during the second forming process, so that there is sufficient material thickness for the deep-drawing, even in the areas of the recesses and in the area between the recesses, and the formation of cracks in the housing or in the foil material during subsequent operation of the Battery cell can be excluded.

In particular, before step d), possibly before or during step c), a sheet metal holder is provided, which fixes the film material in step c) in a step x) in the surface section. In particular, the film material is only fixed in the areas of the surface section that do not prevent the film material from being guided into the surface section.

In particular, the film material is trimmed between steps x) and d) so that the film material only extends over the surface section. The trimming takes place in particular by a first cutting device, which separates the foil material arranged between the die and the stamping tool from the foil material arranged outside of the surface section.

The separation is z. B. by lowering the die and stamping tool in relation to the first cutting device. In particular, as a result of the lowering, die inserts are now inserted into recesses in the die, so that an even contact surface of the die for the foil material is ensured within the surface section and outside of the recesses and the region.

In particular, during step d), a third reshaping or a third reshaping of the film material also takes place in the area of the fold line, in which a bending radius is stamped into the film material along the fold line. The third forming takes place in particular with the preforming punch, which now further forms the area formed by the first forming. The third forming takes place in particular before the second forming, i. H. before forming the foil material in the area of the recesses. To form the bending radius, the stamping tool is used, which interacts in particular with the preforming stamp. In particular, the second forming takes place at the same time as the third forming.

In particular, the third forming only takes place when, as a result of the second forming, the material reservoir formed by the first forming in the area is at least 90%, preferably at least 95%, particularly preferably at least 99%, out of the area and towards the recesses has been moved. In particular, the second forming and the third forming of the film material are completed at the same time.

The bending radius is in particular between 0.5 millimeters and 5 millimeters, preferably at least 1 millimeter, particularly preferably at least 2 millimeters, preferably at most 4 millimeters, particularly preferably at most 3 millimeters.

The fold line is defined by the bending radius impressed by the third forming, so that the folding of the foil material according to step e) takes place automatically along the fold line.

In particular, a final trimming of the foil material takes place during at least the second forming, so that a final geometry of the edge regions of the foil material is thus defined. The trimming or separating takes place in particular via a second cutting device, which is formed in the die and/or the stamping tool. The separation takes place in particular at the same time as the second forming and preferably immediately after the end of the second forming.

In particular, in step e) after the stack has been arranged in the first recess, the second die part is folded onto the first die part. As a result of the folding movement, the film material is folded along the fold line. For this purpose, the matrix parts are connected to one another via a (pivoting) joint.

During the folding movement, the foil material is fixed in the respective recess, in particular only in the moved recess, via a vacuum connection. With the vacuum connection, a vacuum is generated between the foil material and the recess, by which the foil material is held in the recess.

In particular, in a step y), the first matrix part and the second matrix part are pivoted together with the folded film material and the stack into a sealing position and the edge region of the film material is sealed in the sealing position. In particular, the die inserts are not pivoted as well, so that these areas of the die and, via these areas of the die, the edge areas of the foil material are now accessible for a sealing tool.

In particular, after step y), the matrix parts are pivoted back into the starting position and the battery cell is removed from the matrix.

In particular, the foil material is held or remains arranged in the die parts during the forming and up to the sealing according to step y), so that a high level of dimensional accuracy and reproducibility of the dimensional accuracy can be achieved.

• • eine zumindest zweiteilige Matrize mit zumindest einer ersten Ausnehmung in einem ersten Matrizenteil und einer beabstandet zur ersten Ausnehmung angeordneten zweiten Ausnehmung in einem zweiten Matrizenteil, der gegenüber dem ersten Matrizenteil klappbar ausgeführt ist;
• • einen Vorformstempel oder eine Vorformeinrichtung sowie
• • ein Stempelwerkzeug mit zu den Ausnehmungen korrespondierenden Stempelgeometrien.

A forming device for producing a housing for a battery cell is also proposed, the forming device being designed to be suitable for carrying out the method described. The forming device comprises at least

• • an at least two-part die with at least one first recess in a first die part and a second recess, spaced apart from the first recess, in a second die part, which is designed to be foldable relative to the first die part;
• • a preforming punch or a preforming device as well as
• • a stamping tool with stamping geometries corresponding to the recesses.

In particular, the forming device includes a control unit that is equipped, configured or programmed to carry out the described method.

A battery cell is also proposed, at least having a gas-tight housing produced by the method described and at least one stack of electrode foils arranged one on top of the other arranged therein. The case is formed by a sheet material having a fold line along a side face of the case.

The housing is in particular formed by a single film material, the housing being formed by folding the film material.

In the case of the housing, no sealing seam is required to seal off the edge region, at least on one side surface of the housing. In the (remaining) edge areas, the film materials lying on top of one another are connected to one another in a gas-tight manner, in particular via a sealed seam.

A battery cell arrangement is also proposed, at least comprising the battery cell described or the battery cell produced by the method described and a cooling surface, the battery cell being arranged on the cooling surface via the edge region (without a sealing seam) or being in thermally conductive contact. In particular, the battery cell arrangement includes a plurality of battery cells.

The cooling surface is in particular a solid, which is preferably on a side facing away from the cooling surface of a cooling fluid, z. B. a liquid or a gas, is applied or flows through.

In particular, during operation of the battery cell, heat is dissipated from the battery cell to an environment via the cooling surface. Of course, temperature control of the battery cell via the cooling surface is also possible, i. H. also an at least temporary heating of the battery cell, d. H. a heat conduction from the cooling surface towards the battery cell.

In particular, the battery cell arrangement is used in a motor vehicle, in particular to provide electrical energy for a traction drive.

The explanations regarding the method can be transferred in particular to the forming device and/or the battery cell or the battery cell arrangement and vice versa.

The use of indefinite articles (“a”, “an”, “an” and “an”), particularly in the claims and the description reflecting them, is to be understood as such and not as a numeral. Correspondingly introduced terms or components are to be understood in such a way that they are present at least once and in particular can also be present several times.

As a precaution, it should be noted that the numerals used here (“first”, “second”, ...) primarily (only) serve to distinguish between several similar objects, sizes or processes, i.e. in particular no dependency and/or sequence of these objects, sizes or make processes mandatory for each other. Should a dependency and/or order be necessary, this is explicitly stated here or it is obvious to the person skilled in the art when studying the specifically described embodiment. If a component can occur several times (“at least one”), the description of one of these components can apply equally to all or part of the majority of these components, but this is not mandatory.

• 1: eine Umformvorrichtung gemäß Schritt b) des Verfahrens in einer Seitenansicht im Schnitt;
• 2: die Umformvorrichtung nach 1 gemäß Schritt c) des Verfahrens in einer Seitenansicht im Schnitt;
• 3: die Umformvorrichtung nach 1 und 2 gemäß Schritt c) des Verfahrens in einer Seitenansicht im Schnitt;
• 4: die Umformvorrichtung nach 1 bis 3 gemäß Schritt d) des Verfahrens in einer Seitenansicht im Schnitt;
• 5: die Umformvorrichtung nach 1 bis 4 während Schritt d) des Verfahrens in einer Seitenansicht im Schnitt;
• 6: die Umformvorrichtung nach 1 bis 5 am Ende des Schrittes d) des Verfahrens in einer Seitenansicht im Schnitt;
• 7: die Umformvorrichtung nach 1 bis 6 während Schritt e) des Verfahrens in einer Seitenansicht im Schnitt;
• 8: die Umformvorrichtung nach 1 bis 6 während Schritt e) des Verfahrens in einer Seitenansicht im Schnitt;
• 9: die Umformvorrichtung nach 1 bis 8 während Schritt e) des Verfahrens und nachfolgend zu 8 in einer Seitenansicht im Schnitt;
• 10: die Umformvorrichtung nach 1 bis 9 während Schritt e) des Verfahrens und nachfolgend zu 9 in einer Seitenansicht im Schnitt;
• 11: die Umformvorrichtung nach 1 bis 10 während Schritt e) des Verfahrens und nachfolgend zu 10 in einer Seitenansicht im Schnitt;
• 12: die Umformvorrichtung nach 1 bis 11 während Schritt e) des Verfahrens und nachfolgend zu 11 in einer Seitenansicht im Schnitt; und
• 13: die Umformvorrichtung nach 1 bis 12 während Schritt e) des Verfahrens und nachfolgend zu 12 in einer Seitenansicht im Schnitt.

The invention and the technical environment are explained in more detail below with reference to the attached figures. It should be pointed out that the invention should not be limited by the exemplary embodiments given. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and findings from the present description. In particular, it should be pointed out that the figures and in particular the proportions shown are only schematic. Show it:

• 1 : a forming device according to step b) of the method in a side view in section;
• 2 : the forming device after 1 according to step c) of the method in a side view in section;
• 3 : the forming device after 1 and 2 according to step c) of the method in a side view in section;
• 4 : the forming device after 1 until 3 according to step d) of the method in a side view in section;
• 5 : the forming device after 1 until 4 during step d) of the method in a side view in section;
• 6 : the forming device after 1 until 5 at the end of step d) of the method in a side view in section;
• 7 : the forming device after 1 until 6 during step e) of the method in a side view in section;
• 8th : the forming device after 1 until 6 during step e) of the method in a side view in section;
• 9 : the forming device after 1 until 8th during step e) of the method and subsequently to 8th in a side view in section;
• 10 : the forming device after 1 until 9 during step e) of the method and subsequently to 9 in a side view in section;
• 11 : the forming device after 1 until 10 during step e) of the method and subsequently to 10 in a side view in section;
• 12 : the forming device after 1 until 11 during step e) of the method and subsequently to 11 in a side view in section; and
• 13 : the forming device after 1 until 12 during step e) of the method and subsequently to 12 in a side view in section.

the 1 shows a forming device 34 according to step b) of the method in a side view in section. 2 shows the forming device 34 after 1 according to step c) of the method in a side view in section. 3 shows the forming device 34 after 1 and 2 according to step c) of the method in a side view in section. 4 shows the forming device 34 after 1 until 3 according to step d) of the method in a side view in section. 5 shows the forming device 34 after 1 until 4 during step d) of the method in a side view in section. 6 shows the forming device 34 after 1 until 5 at the end of step d) of the method in a sectional side view. the 1 until 6 are described together below.

The forming device 34 comprises an at least two-part die 6 with a first shape recess 7 in a first die part 8 and a second recess 9 spaced apart from the first recess 7 in a second die part 10, which is designed to be foldable relative to the first die part 8, a preforming punch 14 and a stamping tool 16 with stamp geometries corresponding to the recesses 7, 9 .

The battery cell 1 that can be produced in particular by the method comprises a housing 2 and, arranged therein, a stack 3 of electrode foils 4 arranged one on top of the other (see FIG 13 ). The housing 2 is made from a foil material 5 by folding the foil material 5 .

According to step a), the two-part matrix 6 is prepared. The housing halves are formed from the film material 5 with the recesses 7, 9 and are arranged one on top of the other by folding the film material 5 to form the housing 2.

According to step b), a single film material 5 is provided and the film material 5 is arranged on the die 6 present in a starting position 11 and over the recesses 7, 9 in a surface section 12. The film material 5 is planar. The film material 5 is provided as an endless material.

The film material 5 extends beyond this surface section 12 along an edge of the surface section 12 running parallel to the imaginary fold line 13 . The die 6 is arranged on one side of the foil material 5 .

According to step c), a first reshaping of the film material 5 takes place along an imaginary fold line 13 with a preforming die 14 in a region 15, with the fold line 13 running between the recesses 7, 9. The formed area 15 of the film material 5 forms a material reservoir for the subsequent second forming of the film material 5. The fold line 13, which is only imaginary at this point in time of the method and was only realized later by folding, extends exclusively along a straight line.

The preforming punch 14 is formed between the recesses 7, 9 in the die 6 and is designed to be movable with respect to the die 6. A region 15 encompassing the fold line 13 is formed with the preforming die 14 . The first reshaping takes place without stretching the foil material 5, ie without reducing the material thickness of the foil material 5. In the course of the first reshaping, foil material 5 is fed from outside of the surface section 12 into this surface section 12. As a result of the first reshaping, an extension 33 of the film material 5, which is in particular previously flat, located between the recesses 7, 9 is lengthened by at least 30%.

On the other side of the film material 5, ie opposite the die 6, there is a sheet metal holder 18, by means of which the film material 5 can be fixed in a predetermined position on the die 6. However, the sheet metal holder 18 makes it possible for the foil material 5 to be fed into the surface section 12 during the first forming. The foil material 5 is only fed into the surface section 12 from one direction, by a supply device 23 for the foil material 5 outside the surface section 12, here a roll on which the foil material 5 is wound as endless material. This allows other areas of the foil material 5 to be fixed by the sheet metal holder 18 and the die 6 . The preforming punch 14 deforms the foil material 5 towards the sheet metal holder 18.

During step c), a quantity of film material used for the material reservoir is fed into the surface section 12 from outside the surface section 12 . This allows the film material 5 to be stretched during the second forming process, with the material being sufficiently thick in this area for deep-drawing and the formation of cracks in the housing 2 or in the film material 5 during later operation of the battery cell 1 can be ruled out.

The blank holder 18 is provided before step d) and immediately before step c). The sheet metal holder 18 fixes the film material 5 after step c) in a step x) in the surface section 12. The film material 5 is fixed only in the areas of the surface section 12 that do not prevent the film material 5 from being fed into the surface section 12.

The foil material 5 is trimmed between steps x) and d), so that the foil material 5 only extends over the surface section 12 . The trimming is carried out by a first cutting device 22 which separates the foil material 5 arranged between the matrix 6 and the stamping tool 16 from the foil material 5 arranged outside of the surface section 12 .

The separation is z. B. by lowering the die 6 and stamping tool 16 relative to the first cutting device 22. As a result of the lowering, die inserts 26 are inserted into recesses in the die 5, so that within the surface section 12 and outside the recesses and the area 15 there is a flat surface surface of the matrix 6 for the film material 5 is guaranteed.

The die 6 and the preforming punch 14 are movably mounted via different springs 25, so that the die 6 and preforming punch 14 can be moved independently of one another.

According to step d), a stamping tool 16 with stamping geometries corresponding to the recesses 7, 9 is provided. A second forming of the film material 5 in the region of the recesses 7, 9 takes place with the stamping tool 16, the film material 5 present in the material reservoir being displaced towards the recesses 7, 9 during the second forming.

The stamping tool 16 is arranged on the same side of the foil material 5 as the blank holder 18 . The foil material 5 is shaped towards the die 6 by the stamping tool 16 .

As a result of the displacement of the film material 5 present in the material reservoir, the ability of the film material 5 to be deep-drawn is decisively improved. A stretching of the film material 5 in the area of the recesses 7, 9 can be reduced in this way. During the second forming, the material reservoir is completely dissolved (see 5 ), so that the extension 33 of the film material 5 located between the recesses 7, 9 is returned to the state immediately before the first forming.

Arranged along the recesses 7, 9 in the die 6 are heating elements 24 which can heat the film material 5 for the second forming, at least in some areas. As a result of the heating of the film material 5, the deep-drawing of the film material 5 in the area of the lateral boundaries of the recesses 7, 9 can be improved and the risk of tearing of the film material 5 can be further reduced.

During step d), a third reshaping or a third reshaping of the film material 5 also takes place in the area of the fold line 13, in which a bending radius 19 is stamped into the film material 5 along the fold line 13. The third forming takes place with the preforming punch 14, which now further forms the area formed by the first forming. The third forming occurs before the second forming, i. H. before the forming of the film material 5 in the area of the recesses 7, 9. To form the bending radius 19, the stamping tool 16 is used, which interacts with the preforming stamp 14.

The second forming takes place at the same time as the third forming. The third forming only takes place when, as a result of the second forming, the material reservoir formed by the first forming in the area 15 has been displaced by at least 99% from the area 15 and towards the recesses 7, 9. The second forming and the third forming of the film material 5 are completed at the same time. The fold line 13 is defined by the bending radius 19 impressed by the third forming, so that the folding of the foil material 5 according to step e) takes place automatically along the fold line 13 .

During the second forming, the film material 5 is finally trimmed, so that a final geometry of the edge regions 17 of the film material 5 is thus defined. The trimming or separating takes place via a second cutting device 28 which is formed in the die 6 and the stamping tool 16 . The separation takes place at the same time as the second forming.

7 shows the forming device 34 after 1 until 6 during step e) of the method in a side view in section. 8th shows the forming device 34 after 1 until 6 during step e) of the method in a side view in section. 9 shows the forming device 34 after 1 until 8th during step e) of the method and subsequently to 8th in a side view in section. 10 shows the forming device 34 after 1 until 9 during step e) of the method and subsequently to 9 in a side view in section. 11 shows the forming device 34 after 1 until 10 during step e) of the method and subsequently to 10 in a side view in section. 12 shows the forming device 34 after 1 until 11 during step e) of the method and subsequently to 11 in a side view in section. 13 shows the forming device 34 after 1 until 12 during step e) of the method and subsequently to 12 in a side view in section. the 7 until 13 are explained together below. On the remarks on the 1 until 6 is referenced.

Before step e), the stamping tool 16 is removed from the recesses 7, 9. The blank holder 18 is also removed from the die 6.

According to step e), the stack 3 is arranged in the film material 5 and the film material 5 is closed in all edge regions 17 (except for the edge region 17 formed by the fold) to form the housing 2 and to complete the battery cell 1.

In step e), after the stack 3 has been arranged in the first recess 7, the second die part 10 is folded onto the first die part 8. The film material 5 is folded along the fold line 13 as a result of the folding movement. For this purpose, the die parts 8 , 10 are connected to one another via a (pivoting) joint 31 . During the folding movement, the foil material 5 is fixed in the second recess 9 via a vacuum connection 27 .

During step e), after the stack 3 has been arranged, the film material 5 is folded over the fold line 13 so that the film material 5 is placed one on top of the other in the edge regions 17 and a closed volume of the housing 2 is formed. The stack 3 is arranged in the areas of the film material 5 which are formed as a result of the second forming and which correspond to the recesses 7, 9. These areas, which are shaped according to the recesses 7, 9, are arranged in alignment with one another as a result of the folding, so that a volume for accommodating the stack 3 is formed by the foil material 5 folded on top of one another.

The stack 3 is aligned with the first recess 7 via the collectors 30 of the electrode foils 4 , so that one layer of the stack 3 is fixed relative to the foil material 5 and relative to the matrix 6 . Alignment takes place via a positioning device 29 with rod elements which are arranged in the die 6 and between which the conductors 30 are arranged during the arrangement of the stack 3 in the first recess 7 .

The first matrix part 8 and the second matrix part 10 are pivoted together with the folded foil material 5 and the stack 3 in a step y) into a sealing position 20 and in the sealing position 20 the edge region 17 of the foil material 5 is sealed. The die inserts 26 are not pivoted as well, so that these areas of the die 6 and, via these areas of the die 6, the edge areas 17 of the foil material 5 are now accessible for a sealing tool 32.

After step y), the matrix parts 8, 10 are pivoted back into the starting position 11 and the battery cell 1 is removed from the matrix 6. The housing 2 is formed by a film material 5 which has a fold line 13 along a side face 21 of the housing 2 . There is no sealing seam there or it is not necessary there.

Reference List

1

battery cell

2

Housing

3

stack

4

electrode foil

5

foil material

6

die

7

first recess

8th

first matrix part

9

second recess

10

second matrix part

11

starting position

12

area section

13

fold line

14

preform punch

15

area

16

stamp tool

17

edge area

18

sheet metal holder

19

bend radius

20

seal position

21

side face

22

first cutter

23

deployment device

24

heating element

25

Feather

26

die insert

27

vacuum connection

28

second cutter

29

positioning device

30

arrester

31

joint

32

sealing tool

33

extent

34

forming device

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 2012/022448 A1 [0008]
• EP 3611775 A1 [0009]
• DE 102018104554 A1 [0010]

Claims (10)

Method for producing a battery cell (1), at least comprising a housing (2) and arranged therein at least one stack (3) of electrode foils (4) arranged one on top of the other, the housing (2) being made of a foil material (5) by folding the foil material (5 ) is manufactured; the method comprising at least the following steps: a) Providing an at least two-part die (6) with at least one first recess (7) in a first die part (8) and a second recess (9) arranged at a distance from the first recess (7) in a second die part (10) opposite the first matrix part (8) is designed to be foldable; b) arranging at least one film material (5) on the matrix (6) present in a starting position (11) and over the recesses (7, 9) in a surface section (12); c) first forming of the film material (5) along an imaginary fold line (13) with a preforming die (14) or a preforming device in an area (15), the fold line (13) running between the recesses (7, 9); wherein the deformed area (15) of the foil material (5) forms a material reservoir for the subsequent second deformation of the foil material (5); d) second forming of the foil material (5) in the area of the recesses (7, 9) with a stamping tool (16) with stamping geometries corresponding to the recesses (7, 9), with the foil material (5) present in the material reservoir being pressed during the second forming is shifted to the recesses (7, 9); e) arranging the at least one stack (3) in the film material (5) and sealing the film material (5) in an edge region (17) to form the housing (2) and to complete the battery cell (1). procedure after Claim 1 , wherein during step c) a quantity of film material used for the material reservoir is fed at least partially from outside the surface section (12) into the surface section (12). Method according to one of the preceding claims, wherein before step d) a sheet metal holder (18) is provided, which fixes the foil material (5) after step c) in a step x) in the surface section (12). procedure after patent claim 3 , wherein the foil material (5) is trimmed between steps x) and d), so that the foil material (5) only extends over the surface section (12). Method according to one of the preceding claims, wherein during step d) a third reshaping of the film material (5) in the area of the fold line (13) also takes place, in which a bending radius (19) is stamped into the film material (5) along the fold line (13). becomes. Method according to one of the preceding patent claims, wherein in step e) the second die part (10) is folded onto the first die part (8) after the stack (3) has been arranged in the first recess (7); the foil material (5) being folded along the fold line (13) as a result of the folding movement. procedure after claim 6 , wherein in a step y) the first matrix part (8) and the second matrix part (10) are pivoted together with the folded film material (5) and the stack (3) into a sealing position (20) and in the sealing position (20) the Edge region (17) of the film material (5) is sealed. procedure after Claim 7 , wherein after step y) the matrix parts (8, 10) are pivoted back into the starting position (11) and the battery cell (1) is removed from the matrix (6). Forming device (34) for producing a housing (2) of a battery cell (1), the forming device (34) being suitable for carrying out the method according to one of the preceding claims, the forming device (34) at least an at least two-part die (6) with at least one first recess (7) in a first die part (8) and a second recess (9) arranged at a distance from the first recess (7) in a second die part (10) which is opposite to the first Die part (8) is designed to be foldable; • a preforming stamp (14) or a preforming device and • includes a stamping tool (16) with stamping geometries that correspond to the recesses (7, 9). Battery cell (1), at least having a gas-tight design and by the method according to one of the preceding claims or by the forming device (34). Claim 9 manufactured housing (2) and arranged therein at least one stack (3) of electrode foils (4) arranged one on top of the other; wherein the housing (2) is formed by a sheet material (5) having a fold line (13) along a side surface (21) of the housing (2).

Images