DE102018104554B4 - Battery cell and method - Google Patents

Abstract

Battery cell (1) for a battery, in particular for a motor vehicle, comprising at least one cell casing (2) made from at least one foil material (3) made, for example, from a material containing aluminum, the foil material (3) of the cell casing (2) being formed along at least one fold line (4) is folded in order to provide at least one bag (12) for an electrochemical component (11) of the battery and the bag (12) being closed at least in sections, the film material (3) comprising at least one folding aid (5) which is suitable and is designed to counteract at least one overhang (100) of the film material (3) caused by the folding and wherein the folding aid (5) is designed as at least one depression (6) worked into the film material (3), characterized in that the Depression (6) is provided by at least one deep-drawn section (16) of the film material (3) and that on both sides of the fold line (4) at least one depression (6) is arranged in each case and the depressions (6) are arranged at a substantially equal distance from the fold line (4).

Description

The present invention relates to a battery cell and a method for producing a battery cell. The battery cell comprises at least one cell casing made of at least one sheet material, the sheet material of the cell casing being folded along at least one fold line to provide at least one pouch for an electrochemical component of the battery.

The external shape of a battery cell has a significant impact on the complexity with which the cell can be connected to a cooling device. In addition, the external shape is also very important for the space required in a battery. For example, there is always a space between round cells that often remains unused.

Battery cells designed as pouch cells, which are also called pouch cells or coffee bag cells, have therefore become known in the prior art. The pouch cells often have an aluminum-based foil covering. To do this, two foil parts are often placed around a flat stack of electrodes and welded together. Such bag cells offer a space-saving arrangement and a correspondingly large cooling surface.

the US 2017/0047616 A1 discloses a "Nonaqueous Electrolyte Secondary Battery and a Method of Manufacturing Same" wherein an electrode is suspended in a non-aqueous liquid. It is essential that the bag-shaped film material covers the electrode and electrically insulates the various components from one another.

With the U.S. 8,501,343 B2 bag cells with the features of the preamble of claim 1 have become known.

In order to improve the space requirement and the cooling connection, bag cells have become known in which a bag is formed by folding the film. The bag is then sealed on the three open, unfolded sides. A denser arrangement and a better cooling connection are possible on the folded side due to the saved welding seam.

However, it can be observed with such bag cells that when the film is folded, folds form, with excess material being deposited in the area of the fold line. This material tends to push outward, increasing the width of the pouch cell at that point. This results in an uneven connection to existing cooling devices. In addition, such bag cells cannot be arranged particularly closely due to the overhang.

In contrast, it is the object of the present invention to provide an improved battery cell which preferably has a particularly compact shape that can be easily cooled and which can also be produced particularly economically.

This object is achieved by a battery cell having the features of claim 1 and a method according to claim 8. Preferred developments of the invention are the subject matter of the dependent claims. Further advantages and features of the present invention result from the general description and the description of the exemplary embodiments.

The battery cell according to the invention is intended for a battery, in particular for a motor vehicle. The battery cell comprises at least one cell casing made from at least one film material made from, for example, a material containing aluminum. The cell wrap sheet material is folded along at least one fold line to provide at least one pouch for an electrochemical component of the battery. The bag is closed at least in sections. The film material includes at least one folding aid. The folding aid is suitable and designed to counteract at least one overhang of the foil material caused by the creases. The folding aid is designed as at least one depression worked into the foil material. The folding aid can additionally be designed as at least one local addition of material to the film material. The depression is provided by at least one deep-drawn section of the foil material. At least one depression is arranged on each side of the fold line. The depressions are arranged at a substantially equal distance from the fold line.

The battery cell according to the invention offers many advantages. The folding aid offers a considerable advantage, with which the occurrence of protrusions can be counteracted in an uncomplicated and cost-effective manner. Overhangs that press outwards and increase the width of the bag cell are effectively avoided or at least significantly reduced by the folding aid. As a result, the battery cell according to the invention can be arranged in a battery with considerably less space requirement. By avoiding or reducing the overhang, the battery cell according to the invention also offers a particularly flat or level contact surface, so that a significantly improved cooling connection can be ensured. The folding aid designed as a sink can be particularly be integrated uncomplicatedly into the foil material, so that the battery cell according to the invention can be produced very inexpensively.

According to the invention, the depression is provided by at least one deep-drawn section of the foil material. Such a sink can be produced particularly cost-effectively and economically. In addition, excess material or protruding fold formation can be particularly greatly reduced or even completely avoided by such a deep-drawn section. A depression produced by deep-drawing is preferably provided. It is also possible for the depression to be produced by at least one other suitable forming process.

In particular, the sink is directed towards an interior of the bag. This offers a particularly space-saving accommodation of the depression or the overhang without increasing the outer dimensions of the bag. In particular, the sink is directed inwards when the bag is closed or when the battery cell is in an operational state.

According to the invention, at least one depression is arranged on both sides of the fold line. In this case, the depressions arranged on both sides of the fold line are arranged at a substantially equal distance, in particular at the same distance, from the fold line. This results in particular in the fact that the depressions are opposite one another at the same height in the bag. Wrinkling can be prevented particularly well in this way. It is possible that the distance to the fold line is chosen such that the sink touches and/or intersects the fold line.

In particular, the depressions are arranged at a substantially equal distance, in particular the same distance, from a side of the film material running transversely to the fold line. For example, the depressions are arranged symmetrically on both sides of the fold line, with the fold line in particular representing a mirror axis.

However, it is also possible for at least one depression to be arranged only on one side of the fold line. It is also possible that the depressions are arranged at different distances from the fold line. In this case, the depressions are in particular offset opposite one another in the bag.

In particular, at least one depression is arranged on at least one side of the film material running transversely to the fold line. At least one depression is preferably arranged on two opposite sides, which run transversely to the fold line.

It is possible for at least one additional material to be arranged on both sides of the fold line. The material allowances can be arranged at a substantially equal distance, in particular the same distance, from the fold line. It is also possible and preferred that at least one material allowance is arranged only on one side of the fold line. The material allowance can be arranged on at least one side of the film material running transversely to the fold line. It is also possible and preferred that the material allowance is arranged on two opposite sides, which run transversely to the fold line.

In an advantageous embodiment, the depression is arranged in an enlarged section of the foil material. The widening section protrudes in particular from at least one side of the film material running transversely to the fold line. The fact that the sink is relocated to the expansion section has the particular advantage that the area of the film material that can be used to accommodate the electrochemical component is not unnecessarily reduced. In addition, the formation of folds can be prevented particularly well with a depression arranged there.

In particular, at least one expansion section is arranged on two opposite sides of the film material, which run transversely to the fold line. In particular, an expansion section comprises at least one sink and particularly preferably at least two sinks. In particular, the fold line runs through the extension section. In particular, the expansion section is divided into two halves by the fold line, with at least one depression being arranged in each half. However, it is also possible for at least one separate expansion section to be provided for each depression.

In particular, the extension section is shorter than the side running transversely to the fold line. However, it is also possible for the extension section to extend over the entire page, which runs transversely to the fold line. The extension section can also be arranged on another side, e.g. B. on one side with the fold line.

At least one additional material can be arranged on the expansion section. The expansion section can also be formed by adding material.

It is possible that the sink will intersect with the fold line. It is also possible for the depression to be delimited at least in sections by the fold line. Since wrinkling occurs particularly frequently in these areas, so that the arranged there depression can compensate particularly well for the excess material.

In a preferred embodiment, the additional material includes at least one tab. In particular, the tab is unfolded along at least one further fold line and in particular placed on the bag. Such a flap has the advantage that the excess material can be placed close to the bag, so that the excess material only insignificantly affects the dimensions of the bag. In addition, such a tab enables a particularly flat cooling surface. The tab is arranged in particular where protruding folds form, so that the excess can be folded over with the tab and placed on the bag in a targeted manner.

In particular, the folded flap is attached to the bag. For example, the tab is welded and/or glued. In particular, the tab protrudes from an outer contour of the film material. For example, the tab protrudes on at least one side of the foil material running transversely to the fold line. The tab may also protrude from a side of the sheet material that is in the same direction as the fold line. It is possible for at least one depression to be arranged in the tab.

The additional fold line preferably runs at an angle to the fold line. This has the advantage that the flap can be placed particularly tightly against the bag without further unfavorable folds forming. For example, the further fold line runs at an angle of 45° with a margin of +/-15° to the fold line. However, it is also possible for the further fold line to run more acutely or flatly in relation to the fold line. It is possible that the further fold line is arranged at an angle of 90° with a margin of +/-15° to the fold line.

In all of the configurations, it is preferred that the foil material comprises at least one deep-drawn receiving space for the electrochemical component. In this case, the folding aid is arranged in particular outside of the receiving space in the foil material. As a result, the film material can enclose the electrochemical component particularly closely, so that very compact and space-saving battery cells are possible. In particular, the sink does not correspond to the deep-drawn receiving space. However, it is also possible for the folding aid to be arranged at least partially in the receiving space.

In one embodiment, at least one receiving space can be arranged on each side of the fold line. In particular, the two recording spaces can complement each other in the manner of two halves. For example, the two receiving spaces can be joined together like two half-shells. The receiving space is curved in particular towards an outside of the bag. In particular, the receiving space is curved in a direction opposite to the depression.

In the case of a bag cell with a deep-drawn receiving space, a particularly marked formation of folds usually occurs. In particular, excess material is deposited on the fold line in the area of the transition between the deep-drawn receiving space and the non-deep-drawn areas of the film material or the film areas lying on top of one another. As a result, the width of such bag cells increases in a particularly unfavorable manner. The bag cell presented here therefore offers a particular advantage in an embodiment with at least one deep-drawn receiving space. The formation of creases in bags with deep-drawn receiving spaces can be counteracted particularly effectively by the folding aid. In addition, the receiving space can be deep-drawn together with the depression, so that cost-effective production is possible.

The folding aid preferably borders on the folding line. The folding aid can touch and/or overlap the fold line. In particular, the tab is adjacent to the fold line. It is also possible that the widening section and/or the depression border on the fold line.

In an advantageous embodiment, the folding aid is arranged on at least one corner area of the bag. In the corner area, in particular, the fold line meets a side of the bag running transversely to the fold line. There, the folding aid can be used particularly effectively to avoid or reduce overhangs.

In particular, the folding aid is at least partially arranged on an underside of the bag. The underside is in particular the side on which the fold line runs. The folding aid can also be arranged at least partially on another side of the bag.

The method according to the invention is used to produce the battery cell described above for a battery, in particular for a motor vehicle. The battery cell comprises at least one cell casing made from at least one film material made from, for example, a material containing aluminum. The cell wrap sheet material is folded along at least one fold line to provide at least one pouch for an electrochemical component of the battery. The bag is at least partially and in particular completely closed. The foil material is equipped with at least one folding aid in order to counteract at least one overhang of the foil material caused by the creases. For this purpose, the foil material is deep-drawn in certain areas and can be equipped with at least one additional material.

The method according to the invention offers many advantages. It offers particularly economical production of compact battery cells. For example, the thermoforming of the film material is a particularly effective and at the same time inexpensive to produce folding aid. Adding material can also be implemented easily and economically and offers a significant reduction or avoidance of overhangs.

According to the invention, the battery cell described above is produced by the method according to the invention. In particular, the battery cell described above can be produced using the method according to the invention.

In a preferred embodiment, the foil material is deep-drawn at least in an area outside the folding aid in order to produce at least one receiving space for the electrochemical component. Such a configuration is particularly economical since the receiving space and the deep-drawn folding aid can be produced in a common production step. In this way, protrusions or the formation of folds can be avoided without an unfavorable additional effort.

In particular, the deformation is incorporated before folding. However, it is also possible for the deformation to be incorporated after folding. The material is added in particular when the film material is cut to size. However, it is also possible for the additional material to be added to the film material after it has been cut.

The film material which is deep-drawn in some areas is preferably pressed in during the folding and/or after the folding. In particular, a depression created by deep-drawing is indented during folding and/or after folding. In particular, the inside of the bag is pressed.

The material allowance is preferably turned over during the folding and/or after the folding and in particular placed against the bag. For example, the tab is attached to the bag by welding and/or gluing and/or other suitable joining methods.

The battery cell is designed in particular as a pouch cell. The battery cell is designed in particular as a lithium-ion cell. In particular, the electrochemical component comprises at least one electrode and preferably at least one electrode stack. It is possible for at least one connection device and, for example, a supply line to emerge on at least one side of the battery cell.

In particular, the bag comprises at least four sides. In particular, the bag comprises at least two opposite sides which are transverse to the fold line. In particular, the bag comprises at least one side opposite the fold line.

In particular, the bag is closed at the sides and preferably sealed. For example, the bag is sealed. In particular, the film material lying on top of one another is joined and preferably welded on the unfolded sides or the sides outside of the fold line. Other joining techniques are also possible. The pouch is preferably inherently sealed along the fold line. However, it is also possible for an additional connection of the film regions lying on top of one another to be provided along the fold line.

In particular, the bag has an at least approximately rectangular or square shape. Other shapes are also possible, for example the bag can be designed to be polygonal.

In particular, the fold line runs straight. It is also possible for the fold line to run unevenly and, for example, in a curve. The fold line preferably divides the film material into two film areas. In particular, the electrochemical component can be accommodated between these foil areas. The two film areas are in particular joined together. In particular, at least one receiving space is arranged in each film area.

Further advantages and features of the present invention result from the exemplary embodiment, which is explained below with reference to the attached figure.

• 1 eine stark schematische Batteriezelle in einer Draufsicht;
• 2 eine stark schematische erfindungsgemäße Batteriezelle mit einem ungefalteten Folienmaterial in einer Draufsicht; und
• 3 eine stark schematische Detailansicht einer erfindungsgemäßen Batteriezelle mit einem gefalteten Folienmaterial in einer Draufsicht.

In the figures show:

• 1 a highly schematic battery cell in a plan view;
• 2 a highly schematic battery cell according to the invention with an unfolded film material in a plan view; and
• 3 a highly schematic detailed view of a battery cell according to the invention with a folded film material in a plan view.

the 1 shows a battery cell 1 according to the invention designed as a pouch cell. The foil material 3 is made of a material containing aluminum, for example.

The film material 3 is folded along a fold line 4 here, resulting in a bag 12 . An electrochemical component 11 and, for example, an electrode stack are accommodated in the bag 12 here. Connection devices 21 for contacting the electrochemical component 11 are provided here on two opposite sides 101 , 102 running transversely to the fold line 4 . The connection devices 21 are designed here as electrical connections.

On the sides 101, 102 and on a side 103 opposite the fold line 4, the bag 12 is tightly closed here and welded, for example. The fold line 4 is arranged on one side 104 .

The film material 3 was here provided with a receiving space 23 for the electrochemical component 11 on both sides of the fold line 4 using a deep-drawing technique. The receiving spaces 23 serve here as half-shells, which are brought together by folding along the fold line 4 . For example, the receiving spaces 23 can also be formed by deep-drawn areas.

When the film material 3 is folded along the fold line 4, corresponding battery cells 1 from the prior art generally fold. To illustrate such a formation of folds, a projection 100 is indicated schematically in the example shown here, which, however, would not occur in the present invention. The supernatant 100 occurs z. B. at a corner area 22, where the fold line 4 meets the sides 101,102. The protruding folds or the overhang 100 lead to an increase in the external dimensions of the bag 12 or the battery cell 1. In the present invention, the folds or overhangs can be reliably avoided.

During the formation of folds in conventional pouch cells, excess material is deposited on the fold line 4 in the area of the transition between the deep-drawn receiving spaces 23 and the non-deep-drawn areas. The excess material is pressed outwards as an overhang 100 and increases the width of the bag cell 1 in this area. As a result, in contrast to the present invention, an optimal cooling surface for connection to a cooling device cannot be guaranteed.

In the 2 a battery cell 1 according to the invention is shown. The battery cell 1 is manufactured using the method according to the invention. The battery cell 1 has here in addition to the reference to 1 features described on a folding aid 5. This effectively prevents the overhang 100 caused by folding.

The battery cell is shown here in an unfolded state. In order to produce the pouch 12 for holding an electrochemical component 11 , the foil material 3 is folded along the fold line 4 . A deep-drawn receiving space 23 is provided on each side of the fold line 4 . For the sake of clarity, the electrochemical component 11 has not been drawn in here.

The folding aid 5 here comprises two or four depressions 6 worked into the film material 3 . The depressions 6 are each provided by a deep-drawn section 16 of the film material 3 . The deep-drawn sections 16 are shown hatched here. The deep-drawn sections 16 can be designed, for example, as an extension of a deep-drawn receiving space 23 for receiving the electrochemical component 11 . The depressions 6 are essentially the same distance from the fold line 4 here. The sinks 6 can intersect with the fold line 4 or be delimited by it.

The depressions 6 are arranged in a corner area 22 of the bag 12 here.

The depressions 6 are deep-drawn here in such a way that they extend into the interior of the bag 12 . The excess material can be used or compensated accordingly by the depressions 6 . This effectively prevents a projection 100 from forming or excess material from protruding outwards.

In an optional embodiment, the battery cell 1 shown here can be configured with a sink 6 shown here with a broken line. In such an embodiment, a single sink extends on both sides of the fold line 4. Such a sink, for example, fulfills the function of the two separate sinks 6 described above. The sink 6 is formed in particular by a continuous deep-drawn section 16.

After the film material 3 has been folded, the excess material can be automatically pressed into the interior of the bag 12 by the deep-drawn sections 16 . It can also be provided that, after the film material 3 has been folded, the deep-drawn sections 16 are pressed inwards in a targeted manner, so that the depressions 6 point into the interior of the bag 12 .

In addition, such a folding aid 5 with one or more depressions 6 is also in the 1 drawn. A recess 6 designed as a deep-drawn section 16 is shown hatched there.

the 3 shows a battery cell 1 according to the invention, which is equipped here with a folding aid 5 designed as a material allowance 7 . The battery cell 1 is shown here in part. The foil material 3 is folded along the fold line 4 to form a bag 12 . The overhang 100 caused by the folding can be significantly reduced here by the folding aid 5.

The material allowance 7 is designed here as a tab 17 which is arranged in a corner area 22 of the bag 12 . This positioning allows an overhang 100 to be leveled out or placed tightly against the bag 12 by folding over the flap 17 .

The tab 17 is arranged here along the fold line 4 so that any excess material or protruding material 100 that is produced there can be folded particularly well in the direction of the tab 17 . As a result, a lateral protrusion of the overhang 100 is avoided in a particularly effective manner.

The flap 17 is folded over here along a further fold line 27 which runs at an angle to the fold line 4 . The folded flap 17 is preferably attached to the bag 12 in order to allow the flattest possible cooling surface.

The battery cell 1 shown here preferably also has a material allowance 7 designed as a tab 17 on the opposite corner region 22 . In this way, the overhangs 100 that occur in this corner area 22 during folding can also be removed or reduced by folding them over.

The material allowance 7 shown here can be produced, for example, by an extended cutting of the foil material 3 .

The one in the 2 shown embodiment of the folding aid 5 as a sink 6 can with the in the 3 shown, designed as a material allowance 7 folding aid 5 are combined and vice versa.

Such a material addition 7 is also in the 1 outlined in dashed and dotted lines.

Claims (8)

Battery cell (1) for a battery, in particular for a motor vehicle, comprising at least one cell casing (2) made from at least one foil material (3) made, for example, from a material containing aluminum, the foil material (3) of the cell casing (2) being formed along at least one fold line (4) is folded in order to provide at least one bag (12) for an electrochemical component (11) of the battery and wherein the bag (12) is closed at least in sections, the film material (3) comprising at least one folding aid (5) which is suitable and designed to counteract at least one overhang (100) of the film material (3) caused by the folding and wherein the folding aid (5) is designed as at least one depression (6) worked into the film material (3), characterized in that the Depression (6) is provided by at least one deep-drawn section (16) of the film material (3) and that on both sides of the Faltli never (4) at least one sink (6) is arranged and wherein the sinks (6) are arranged at a substantially equal distance from the fold line (4). Battery cell (1) according to the preceding claim, wherein the depressions (6) are directed into an interior of the bag (12). Battery cell (1) according to one of the preceding claims, wherein the folding aid (5) is designed as at least one local material allowance (7) of the film material (3) and wherein the material allowance (7) comprises at least one tab (17) which runs along at least one another fold line (27) is turned over and applied to the bag (12). Battery cell (1) according to the preceding claim, wherein the further fold line (27) runs obliquely to the fold line (4). Battery cell (1) according to one of the preceding claims, wherein the foil material (3) comprises at least one deep-drawn receiving space (23) for the electrochemical component (11) and wherein the folding aid (5) is arranged outside of the receiving space (23) in the foil material (3). is. Battery cell (1) according to one of the preceding claims, wherein the folding aid (5) is adjacent to the fold line (4). Battery cell (1) according to one of the preceding claims, wherein the folding aid (5) is arranged on at least one corner area (22) of the bag (12). Method for producing a battery cell (1) according to one of the preceding claims.

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