DE102022106343A1 - Energy storage arrangement for a motor vehicle and method for producing an energy storage arrangement - Google Patents

Abstract

The invention relates to an energy storage arrangement (62, 26) for a motor vehicle, wherein the energy storage arrangement (62, 26) comprises at least one battery cell (26) which has a cell interior (58), a cell housing (56) which has the cell interior (58). includes, and a cell chemistry unit (24, 24a, 24b, 24c, 24d) arranged inside the cell (58). The energy storage arrangement (62, 26) is designed to extract a gas (20) created in the cell interior (58) from a central area (32) of the cell chemistry unit (24, 24a, 24b) when the energy storage arrangement (62, 26) is in the intended operating state. 24c, 24d) in the direction of at least a first edge region (34) of the cell chemistry unit (24, 24a, 24b, 24c, 24d).

Description

The invention relates to an energy storage arrangement for a motor vehicle, wherein the energy storage arrangement comprises at least one battery cell which has a cell interior, a cell housing which encloses the cell interior, and a cell chemistry unit arranged in the cell interior. Furthermore, the invention also relates to a method for producing an energy storage arrangement.

Examples of energy storage arrangements include high-voltage batteries for electric vehicles. These typically have numerous battery cells, for example lithium-ion cells, which can be provided or installed in different packaging forms, for example in the form of round cells, prismatic cells or pouch cells.

The DE 10 2012 018 058 A1 describes a battery cell for a high-voltage battery with an outer shell, which has two cladding plates and at least one insulating frame arranged between them, and with cell chemistry arranged within the outer shell, as well as a drain opening, which is closed in the normal state by a layer of material, and which is in the case an overpressure opens by at least partially destroying the material layer. Furthermore, the battery cell comprises a channel which is arranged in an edge region between the cell chemistry and the outer shell and which is connected to the drain opening. In the event of an undesirable incorrect reaction, such as overcharging, a short circuit or the like, an undesirable exothermic chain reaction in the cell chemistry can occur, which is also referred to as thermal runaway. In this case, the drain opening should open to allow a controlled pressure reduction in the cell. The intended channel should enable a reliable flow of gas from the area of cell chemistry.

But gas can arise in such a battery cell not only in such critical operating states of battery cells, but also in a normal operating state of such a battery cell, which in the context of the present invention is also referred to as the intended operating state of the battery cell. In this intended operating state, there is no defect in the cell and it is functioning properly. Over the course of its service life, such a battery cell, such as a lithium-ion cell, is subject to various aging effects. For example, so-called swelling occurs in the battery cell. This swelling within the cell develops through expansion of the active materials of the cell's anode and cathode. This swelling is superimposed over the lifespan by the formation of gas, which remains in the cell and leads to additional swelling, i.e. swelling, of the cell. Uncontrolled swelling and completely suppressed swelling lead to a reduced service life. Therefore, a defined pressure on the cells is advantageous in order to enable controlled swelling of the cells.

The object of the present invention is to provide an energy storage arrangement and a method which make it possible to improve the functioning of a battery cell in its intended operating state and in particular to increase its service life.

This task is solved by an energy storage arrangement and a method with the features according to the respective independent patent claims. Advantageous embodiments of the invention are the subject of the dependent claims, the description and the figures.

An energy storage arrangement according to the invention for a motor vehicle has at least one battery cell which comprises a cell interior, a cell housing which encloses the cell interior, and a cell chemistry unit arranged in the cell interior. The energy storage arrangement is designed to divert a gas created inside the cell from a central region of the cell chemistry unit in the direction of at least a first edge region of the cell chemistry unit when the energy storage arrangement is in the intended operating state.

The invention is based on several findings: As mentioned at the beginning, gas can form inside the battery cell over the lifespan of a battery cell. In conventional cells, the resulting gas bubbles remain between the anode and cathode and cause the films to lift off from each other. This in turn leads to ions being hindered on their way to the corresponding electrode, which impairs the functioning of conventional battery cells. In addition, the gas bubbles expand and shrink due to the pressure changes during charging and discharging of the conventional battery cell, which creates mechanical stress in relatively brittle active materials. In the case of prismatic battery cells, for example, the cell housings are constructed in such a way that they have significantly greater rigidity, especially in the edge area. The structural design of the clamping of the stacks or wraps or, in general, the cell chemistry unit Significantly higher forces are applied to the stack or the electrode coil in the edge area than in the center of the battery cell. In the worst case scenario, this creates increased compression in the edge area and thus creates a kind of seal that prevents the gas bubbles from easily escaping. As a result, flat gas bubbles form in the middle of the cell. Consequently, gases generated inside the cell during normal operation of a conventional battery cell can also affect the functionality and lifespan of such a battery cell. The invention now advantageously makes use of this knowledge and accordingly provides for a design of the energy storage arrangement in such a way that it is now also possible in an intended operating state, which is therefore different from a faulty state of the energy storage arrangement or one of its cells, in particular by means of a special one constructive design of either the battery cell itself or a further component of the energy storage arrangement to divert a gas created inside the cell from a central region of the cell chemistry unit in the direction of at least a first edge region of the cell chemistry unit. This can advantageously minimize the formation of flat gas bubbles between the layers of the cell, that is, the individual electrodes and separator layers of the cell chemistry unit. The fact that the invention advantageously makes it possible to direct the gas specifically into edge areas of the cell results in numerous advantages. On the one hand, the pumping movement of the gas bubbles when charging and discharging the cell can be minimized, and this reduces the mechanical stress and the flexing movement on the coatings of the anode or cathode of the cell chemistry unit and reduces the risk of detachment. In addition, the electrically active surface is not interrupted by gas bubbles or this interruption is also reduced. Furthermore, this also reduces the cambering of the cell in the cell center and also provides a more homogeneous and reduced electrical aging of the battery cell. The invention therefore results in numerous advantages in terms of improving the functionality of the battery cell and extending its service life. Furthermore, the invention is also based on the knowledge that possibilities are currently being sought to remove the gas that develops inside the cell over the course of its lifespan during normal operation of the battery cell, and not only in an emergency in the event of overpressure or thermal runaway Battery cell. For this purpose, too, it is advantageous to be able to specifically drain the gas generated in the cell from a central area of the cell to an edge area, so that from there it can be drained much more easily into the environment of the cell through a suitable exhaust device, even during normal operation of the cell can be.

In principle, the invention can be used for any type of battery cell, in particular for prismatic cells, pouch cells and round cells. However, the invention is particularly advantageous when the at least one battery cell is, for example, a prismatic cell, since prismatic battery cells in particular have cell housings which can lead to the above-described sealing of the electrode layers in the edge region. Pouch cells, for example, typically have significantly more flexible, bag-like cell housings, which are therefore inherently significantly less affected by the problem described above. It is therefore particularly advantageous if the at least one battery cell is designed, for example, as a prismatic cell with a prismatic cell housing. Furthermore, the at least one battery cell can be, for example, a lithium-ion cell.

The energy storage arrangement can generally be, for example, a high-voltage battery for an electric vehicle mentioned at the beginning, or even just a part of such a high-voltage battery, for example a battery module with several battery cells or even just the at least one battery cell itself. If the energy storage arrangement has, for example, several battery cells, in particular several prismatic battery cells, which are combined to form a cell stack, these are arranged next to one another with respect to a first direction. This first direction can therefore correspond to a stacking direction of such a cell stack. The above-mentioned direction in which the gas created inside the cell is diverted from the central region of the cell chemistry unit to the edge region of the cell chemistry unit can be at least partially aligned perpendicular to this first direction. For example, gases are discharged between the individual layers of the cell chemistry unit or parallel to these layers. However, derivation can also take place at least partially parallel to this first direction, in particular through the layers of the cell chemistry unit, as described in more detail later.

As already defined at the beginning, the intended operating state of the energy storage arrangement should not be a defective state or faulty state and, above all, not a state in which the at least one battery cell is thermally runaway or is in the process of thermally runaway. The intended operating state can be defined, for example, such that operating parameters of the at least one battery cell are defined for the battery cell Move to normal range. Operating parameters include, for example, the temperature, pressure and/or voltage of the battery cell. A discharge of the gases from the central area into the edge area is therefore permanently possible and takes place permanently when gas is produced, at least until the pressure conditions in the cell have equalized.

In a further very advantageous embodiment of the invention, the battery cell has at least one degassing channel arranged in the interior of the cell in order to drain the gas produced inside the cell from the central region of the cell chemistry unit in the direction of the at least one first edge region of the cell chemistry unit. This degassing channel can therefore be used advantageously to direct the gas towards the edge area. This degassing channel therefore preferably leads from at least a central area of the cell chemistry unit into an edge area. By providing such a degassing channel, gas can advantageously reach the edge region of the cell much more easily even during normal operation of the battery cell. This enables a significantly more homogeneous pressure distribution and reduces cell bulging.

In addition, not only one such degassing channel can be provided, but also several degassing channels. These can, for example, also lead to different edge areas of the cell chemistry unit. However, the degassing channel itself can also lead from an edge area to an opposite edge area and through the central area of the cell chemistry unit. Gas can thus be derived from the central region of the cell chemistry unit, in particular two opposite edge regions of the cell chemistry unit. This advantageously also enables a particularly uniform gas distribution inside the cell and also a particularly uniform gas distribution to the edge regions of the cell chemistry unit or the cell interior.

The design of such a degassing channel can now take various forms, which are explained in more detail below. In general, the cell chemistry unit has a separator and two electrode layers spatially separated from the separator, with each electrode layer having a carrier layer and an active material layer arranged on the carrier layer. For example, one of the electrode layers represents an anode layer and the other a cathode layer. The anode layer and the cathode layer are completely separated from each other by the separator mentioned. The cell chemistry unit can be constructed in different ways from such layers, namely the electrode layers and the separator. For example, the cell chemistry unit can be constructed in the form of a stack or stack of several such alternating layers. The layer sequence can be, for example: anode layer, separator, cathode layer, separator, anode layer, separator, and so on. The cell chemistry unit can accordingly also have several anode layers and cathode layers that are not connected to one another, but are separated from one another by respective separator layers. However, only one anode layer and one cathode layer can be provided, which are wound into a cell coil using separators that separate these two layers. Such a cell coil can then have a round or oval geometry in its cross section. The respective carrier layers of a respective anode layer are preferably made of a metallic material, for example copper or aluminum. The corresponding carrier layers can, for example, be provided as respective metal foils; a corresponding active material is in turn applied to these metal foils to provide the active material layer. The active materials for the anode and cathode differ from each other.

If the cell chemistry unit is arranged in the cell housing, it is also in a state immersed in an electrolyte. The electrode stack or electrode wrap is completely immersed in such an electrolyte.

In a further very advantageous embodiment of the invention, it is now provided that the at least one degassing channel is provided by at least one groove in at least one of the active material layers. This has several major advantages: On the one hand, such grooves can be particularly easily introduced into active material layers. Active material layers can, for example, be rolled onto a corresponding carrier layer using a roller in the production of battery cells or cell chemistry units. In order to introduce at least one such groove or even a groove pattern into the active material layer, such a roller can be provided, for example, with a complementary groove pattern. Such a roller can, for example, have elongated elevations on its cylindrical roller surface, which introduce corresponding grooves into the active material layer when it is rolled onto the carrier layer using this roller. Such a groove therefore represents a depression, in particular an elongated or elongated depression, in the active material layer. Due to this manufacturing process, the active material in the area of the groove must be more compressed than in other areas of the active material layer without a groove. However, it is also conceivable, although less preferred, for the active material layer to be completely missing from the corresponding carrier layer in the area of the groove to form this.

However, for efficient gas removal from the central area of the cell chemistry unit, it is already sufficient if there is either less active material in the area of the groove and/or it is more compacted. This also has the advantage that active material is also present in the area of the groove, which promotes the storage capacity of the cell. The performance is therefore not, or at least not noticeably, impaired by the formation of one or more grooves. In addition, the corresponding anode layer is still very stable, since at least the carrier layer is not severed in the area of the groove, but is designed continuously. This also makes the production of the battery cell easier, especially compared to the embodiment with a slot described in more detail below.

In a further advantageous embodiment of the invention, the at least one groove runs at least from a central region of the active material layer in relation to a second direction perpendicular to the first to a first edge region of the active material layer, in particular from a second edge region of the active material layer through a central region to first area of the active material layer. The first edge region of the active material layer can correspond to the first edge region of the cell chemistry unit. However, the edge area of the cell chemistry unit can be somewhat further out from the central area than the edge area of the active material layer. This is particularly the case when the separator layer described extends further beyond the electrode layers than the electrode layers themselves extend outwards towards the edge, in order to ensure a secure spatial and electrical separation of these electrode layers, especially in edge areas. The fact that the groove also extends from one edge region to the opposite edge region has the great advantage that gases can be directed particularly evenly from the central region to two opposite edge regions. This ensures a particularly homogeneous pressure distribution in the cell.

In a further advantageous embodiment of the invention, several grooves are arranged in the electrode layer, which overlap and run in different directions, in particular in a straight line. If the battery cell is designed, for example, as a prismatic battery cell, it can have, for example, four edge areas that surround the central area. Gases can be directed into these four edge areas simultaneously through two overlapping grooves. Such intersection points or crossing points also enable particularly efficient gas removal.

According to a further very advantageous embodiment, the at least one groove is provided as a groove pattern with several grooves. The efficiency of gas removal can be optimized in this way. In principle, just a few grooves are sufficient to enable gases to be efficiently removed from the central area of the cell to the edge areas. Providing only a few grooves, for example in the single-digit range, does not impair the functionality of the battery cell due to excessive reduction of the active material.

A further advantageous embodiment of the invention is when the at least one degassing channel is provided by at least one slot in at least one of the electrode layers. In other words, the degassing channel can be provided not only as a channel in the active material, but also as a continuous slot through the entire electrode layer, that is, the active material layer including the carrier layer. Such a slot can also advantageously provide a channel which extends in particular at least from the center of the cell chemistry unit to an edge region and which facilitates the removal of gases from the central region into the edge region. Such a slot then preferably does not extend from one edge region to the opposite edge region, since this would divide the corresponding electrode layers into two parts. The slot is designed, so to speak, merely as an incision in the electrode layer, but not as an average in relation to a direction perpendicular to the surface normal of the electrode layer.

According to a further advantageous embodiment of the invention, the at least one slot extends at least from a central region of the electrode layer in relation to a second direction perpendicular to the first to a first edge region of the electrode layer. However, when providing the degassing channel as a slot, it is not preferred that it extends continuously from a second edge region of the electrode layer to the first edge region of the electrode layer, since this would divide the electrode layer.

According to a further advantageous embodiment of the invention, two of the electrode layers arranged to overlap in the first direction each have a slot, the two slots being offset from one another with respect to at least one direction perpendicular to the first. The two electrode layers can be, for example, an anode layer and a cathode layer or even two anode layers. The great advantage of this configuration is that a kink in the cell chemistry unit can be avoided, as would be the case if the respective slots were arranged one above the other in the first direction. The staggered arrangement of the slots can increase the stability of the individual layers in their overall composite, and thus the stability of the cell chemistry unit.

Preferably, not only one electrode layer has a described degassing channel, for example in the form of a groove in the active material layer or as a slot, but rather several electrode layers. This can be several anode layers as well as several cathode layers or just one anode layer and one cathode layer.

According to a further advantageous embodiment of the invention, the at least one degassing channel is at least partially provided by a through opening penetrating the two electrode layers and the separator, in particular the entire cell chemistry unit, in a first direction, which passes through at least one first opening in the separator, and in each case at least a second opening is provided in the two electrode layers, which are arranged overlapping in the first direction, wherein the at least one first opening in the separator is smaller than the respective at least one second opening in the two electrode layers. The through opening can therefore be provided as a type of degassing hole in the center of the cell or cell chemistry unit. The hole in the separator film can be made relatively small in order to effect degassing. In other words, the first opening in the separator film should be at least so large that gas can penetrate the separator film in the area of this first opening. The holes in the anode and cathode, which represent the respective second openings, are larger. This has the advantage that the electrical insulation path can be ensured via the separator film. In other words, the anode layer and the cathode layer cannot touch each other despite the first opening provided in the separator. The through opening can essentially extend in the first direction. As a result, the gas can initially escape in a simplified manner from the intermediate areas between the individual electrode layers and reach the area of the front and/or back of the cell housing and from there in turn in a simplified manner into an edge area of the cell.

The openings can be designed as circular openings and, for example, can be arranged coaxially or concentrically to one another. In principle, however, the openings can have any geometry. The first opening in the separator preferably has a maximum diameter of, for example, a few millimeters or even smaller, for example a diameter smaller than one millimeter. This is already sufficient for gas to penetrate the separator.

Furthermore, the electrode layers and separator layers are designed such that a first opening in the separator is not, or even partially, covered by part of an electrode layer. This ensures the electrical isolation of the anode layer and cathode layer from each other.

According to a further very advantageous embodiment of the invention, in order to divert the gas created inside the cell from the central region of the cell chemistry unit in the direction of the at least one first edge region of the cell chemistry unit, the energy storage arrangement is set up in such a way that a compressive force from outside the cell housing is applied over the cell housing with respect to a first direction can be exerted on the cell interior, which is larger in a central region of the cell housing than in an edge region of the cell housing in relation to a second direction perpendicular to the first direction. In other words, components of the energy storage arrangement can also be designed such that when the battery cell is in the operational state, the pressure that acts on the central region of the cell housing is greater than in an edge region. This also advantageously promotes the escape of gases from the central area of the cell chemistry unit into the edge area. A discharge of gases from the central area of the cell chemistry unit into an edge area is not only made possible by a special design of the cell interior of such a battery cell, but can also be influenced or promoted from the outside. These measures are particularly advantageous as additional measures, in particular in addition to the previously described options for forming a degassing channel inside the cell, but can also, on their own, enable and promote the discharge of gases from the inside of the cell into an edge region of the cell.

In order to provide such a designed compressive force on the cell housing, there are again more There are other options, which will now be explained in more detail below.

According to a further advantageous embodiment of the invention, the energy storage arrangement has a plurality of the at least one battery cell, the plurality of battery cells being arranged next to one another in the first direction, and a cell separating element being arranged between two of the battery cells which are arranged adjacent to one another in the first direction , which has less flexibility in a central area than in an edge area. Here too, the central area can again be defined in at least one second direction perpendicular to the first direction. The multiple battery cells can, for example, be part of a cell stack braced in the first direction. Such a clamping device will be explained in more detail below. By means of such a clamping device, for example, a compressive force can be exerted on the cell stack on both sides with respect to the first direction. By cell separating elements between the cells, which are designed so that they have less flexibility in the central area than in the edge area, it is advantageously possible to provide a pressure distribution over the outer surfaces of the cell housing, which allows higher pressure forces in the central area of the cells than in Edge areas.

In order to enable the cell separation element to have less flexibility in a central region than in an edge region, whereby here again the central region and the edge region relate to a direction that is perpendicular to the first direction defined above, the cell separation element can be used in a variety of ways be designed in different ways. For example, the cell separating element can be designed to be convexly curved in the direction of the neighboring cells. The cell separating element can also be provided from a material or sub-elements, so that the cell separating element has a greater spring hardness in the central area than in the edge area. The cell separating element can, for example, comprise one or more springs. However, numerous other training options for such a cell separation element are also conceivable. For example, the cell separation element can also be designed as an air cushion or segmented air cushion or generally as a hydraulic or pneumatic element. Preferably, the cell separation element is made from an elastomer. This enables a particularly simple design with the desired properties described above.

The cell separating element does not have to be the only element that is arranged between two adjacent cells. Additional elements or layers or plates can also be arranged here, for example for the purpose of thermal insulation.

It is particularly advantageous if the cell separating element is designed to be elastic at least with respect to the first direction. This makes it possible to at least partially compensate for the swelling described at the beginning, at least as long as no outlet is provided for the gases produced in the cells during operation of the battery cells.

According to a further advantageous embodiment of the invention, the energy storage arrangement has a cell stack comprising the at least one battery cell and a clamping device for clamping the cell stack in the first direction, the clamping device having pressure plates which delimit the cell stack on both sides with respect to the first direction and by means of which a compressive force is applied the cell stack can be exercised in the first direction, which is larger in a central area of the cell stack than in an edge area of the cell stack in relation to the second direction perpendicular to the first direction. It can also advantageously be achieved through a special design of the pressure plates to provide a pressure force on the cells or their cell housings, which is greater in a central area than in an edge area. The pressure plates can be clamped together, for example, by two side plates. The cell stack can then be arranged between these two side plates and the two pressure plates. Alternatively or additionally, it is also conceivable that these clamping plates or clamping bands are designed in such a way that the tensile force on the pressure plates is designed in such a way that it is greater in a central area than in the edge area. This also makes it possible to exert a compressive force on the respective cell housings, which is greater in the central area than in the edge area.

According to a further very advantageous embodiment of the invention, at least one of the pressure plates has an inner side surface facing the cell stack, which is curved in the direction of the cell stack. This preferably applies to both printing plates. In this way, the effect described above can be achieved in a particularly simple and cost-effective manner, that a compressive force on the cell stack is greater in a central area than in the edge area. Such a curvature can refer both to a second direction that is perpendicular to the first direction and optionally also to a further third direction that is perpendicular to the second and first directions. In other words, the inside surface can be curved two-dimensionally or three-dimensionally be educated. The maximum of such a curvature is then preferably located in the central area of the cell stack or the adjacent battery cell in relation to the second and third directions mentioned.

According to a further advantageous embodiment of the invention, at least a first side of the cell housing of the at least one battery cell has a central area and an expansion contour which runs closed around the central area in order to reduce a curvature of the central area of the first side when the cell chemistry unit is expanded in the first direction, in particular, the expansion contour adjoins an edge region of the first side. This is particularly advantageous if the at least one battery cell is designed as a prismatic cell. The expansion contour can then correspondingly have a substantially rectangular geometry. Such an expansion contour can reduce the rigidity of the cell housing in the edge area. If the cell chemical unit begins to swell over the course of its lifespan, the cell does not bulge in the first direction as described at the beginning and bulges outwards like a dome, but rather the two outer sides of the cell housing with the largest area are pushed apart in and against the first direction via the expansion contour , especially while maintaining their flat geometry or at least approximately. At least the curvature or curvature of the central region of a respective first side of the cell housing can be reduced by providing such an expansion contour. This also advantageously makes it possible for gases generated inside the cell to escape or reach an edge region more easily. The electrode coil or electrode stack is not excessively compressed and sealed along the expansion contour in the edge area, because when the cells swell, the outer surfaces of the cell housing can now expand or move apart in the edge area thanks to the expansion contour, which makes it easier for gases to escape into the edge area.

Furthermore, the invention also relates to a motor vehicle with an energy storage arrangement according to the invention or one of its embodiments.

The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus or motorcycle.

Furthermore, the invention also relates to a method for producing an energy storage arrangement with at least one battery cell, which has a cell interior, a cell housing which encloses the cell interior, and a cell chemistry unit arranged in the cell interior. The energy storage arrangement is manufactured in such a way that, when the energy storage arrangement is in the intended operating state, a gas created inside the cell is diverted from a central region of the cell chemistry unit in the direction of at least a first edge region of the cell chemistry unit.

The advantages described for the energy storage arrangement according to the invention and its design apply equally to the method according to the invention.

According to a further embodiment of the method, in the course of producing the energy storage arrangement, for example, a degassing channel is provided within the battery cell. This degassing channel can be designed in the form of a groove in the active material layer or in the form of a slot in an electrode layer or in the form of a through opening through electrode layers and the separator, as already described in connection with the energy storage arrangement according to the invention and its configurations. The method steps described in connection with these embodiments of the energy storage arrangement for forming the grooves and/or slots and/or through openings can also be viewed as further optional method steps according to exemplary embodiments of the invention.

The invention also includes developments of the method according to the invention, which have features as have already been described in connection with the developments of the energy storage arrangement according to the invention. For this reason, the corresponding developments of the method according to the invention are not described again here.

The invention also includes the combinations of the features of the described embodiments. The invention therefore also includes implementations that each have a combination of the features of several of the described embodiments, provided that the embodiments have not been described as mutually exclusive.

• 1 eine schematische perspektivische Darstellung einer Zellchemieeinheit und deren Aufblähen im Laufe der Zeit bei einer herkömmlichen Batteriezelle;
• 2 eine schematische Darstellung einer Zellchemieeinheit und deren Veränderung im Laufe der Zeit gemäß einem Ausführungsbeispiel der Erfindung;
• 3 eine schematische Darstellung einer Zellchemieeinheit für eine Batteriezelle mit in der Aktivmaterialschicht angeordneten Rillen gemäß einem Ausführungsbeispiel der Erfindung;
• 4 eine schematische Darstellung einer Zellchemieeinheit für eine Batteriezelle mit in den Elektrodenschichten angeordneten Schlitzen gemäß einem weiteren Ausführungsbeispiel der Erfindung;
• 5 eine schematische Explosionsdarstellung einer Zellchemieeinheit für eine Batteriezelle mit einer Durchgangsöffnung gemäß einem weiteren Ausführungsbeispiel der Erfindung;
• 6 eine schematische und perspektivische Querschnittsdarstellung durch eine Batteriezelle gemäß einem weiteren Ausführungsbeispiel der Erfindung;
• 7 eine schematische Darstellung eines Batteriemoduls und dessen Veränderung im Laufe der Zeit gemäß einem Ausführungsbeispiel der Erfindung; und
• 8 eine schematische Darstellung eines weiteren Ausführungsbeispiels eines Batteriemoduls und dessen Veränderung im Laufe der Lebensdauer.

Examples of embodiments of the invention are described below. This shows:

• 1 a schematic perspective representation of a cell chemistry unit and its structure bloat over time in a traditional battery cell;
• 2 a schematic representation of a cell chemistry unit and its change over time according to an embodiment of the invention;
• 3 a schematic representation of a cell chemistry unit for a battery cell with grooves arranged in the active material layer according to an exemplary embodiment of the invention;
• 4 a schematic representation of a cell chemistry unit for a battery cell with slots arranged in the electrode layers according to a further exemplary embodiment of the invention;
• 5 a schematic exploded view of a cell chemistry unit for a battery cell with a through opening according to a further exemplary embodiment of the invention;
• 6 a schematic and perspective cross-sectional view through a battery cell according to a further exemplary embodiment of the invention;
• 7 a schematic representation of a battery module and its changes over time according to an embodiment of the invention; and
• 8th a schematic representation of a further exemplary embodiment of a battery module and its changes over the course of its service life.

The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention that are to be considered independently of one another and which also further develop the invention independently of one another. Therefore, the disclosure is intended to include combinations of the features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the invention that have already been described.

In the figures, the same reference numerals designate functionally identical elements.

1 shows a schematic representation of a cell chemistry unit 10 in a new state N of a conventional battery cell and the cell chemistry unit 10 after a certain time, for example at the end of the service life L or after a certain service life L. The cell chemistry unit 10 is generally located inside a battery cell , in particular enclosed by a cell housing. The cell chemistry unit 10 can include several layers 12 to form an electrode stack. 1 shows such an electrode stack 14 for a prismatic battery cell. Such a prismatic battery cell has a substantially cuboid cell housing, not shown here. Due to the geometry and the structural design of such a conventional cell housing, higher forces are applied to the electrode stack 14 in the edge area than in the center 16. This creates increased compression in the edge area 18 and thus a seal, which prevents easy escape of gas bubbles 20, which are in the Over the lifespan of such a cell, the cells formed in it are hindered. Because these gas bubbles 20 cannot escape from the center 16, a flat gas bubble 22 forms in the middle of the cell or this center 16, which is in 1 is shown in dashed lines. So far there are no concepts to prevent such an accumulation of gas 20 between the layers or layers 12 of the cell. The creation of such large-area gas bubbles 22 between the individual layers 12 in turn results in numerous disadvantages. On the one hand, such gas bubbles remain between the anode and cathode, which are provided by respective layers 12 of the cell chemistry unit 10, and lead to the film lifting off. In other words, the distance between anode layers and cathode layers increases due to the presence of gas bubbles 22, which reduces the functionality of the cell. In addition, the gas bubbles enlarge due to the pressure changes during charging and discharging, which creates mechanical stress in the relatively brittle active materials of the cell.

The formation of such large-area gas bubbles 22 can now advantageously be prevented or reduced in extent by the invention or its embodiments.

2 shows a schematic representation of a cell chemistry unit 24 for a battery cell 26 (see for example 6 ) according to an embodiment of the invention. The cell chemistry unit 24 is again shown on the left in a new state N and on the right after a certain time or after a certain lifespan L. In this example, the cell chemistry unit 24 again comprises several layers 28 stacked in a stacking direction x, which provide an electrode stack 30. These layers 28 can include electrode layers, for example anode layers and cathode layers, as well as separator layers, such as these will be explained in more detail later. Also in relation to this cell chemistry unit 24, for example, a central area 32 can be defined, as well as an edge area 34, more precisely four edge areas 34, which limit the extent of the cell chemistry unit 24 on both sides in the y-direction and z-direction. The central area 32 of the cell chemistry unit 24 does not necessarily have to represent the exact center of the cell chemistry unit 24, for example in relation to the y-direction and z-direction, but can also include a larger area of the cell chemistry unit 24 that includes this center.

Through the exemplary embodiments explained in more detail below, it is now advantageously possible to divert the gas 20 that arises inside the cell over the course of its life from the central region 32 of the cell chemistry unit 24 into the edge region 34. This both improves the functionality of the cell and extends its lifespan. In particular, pumping movements of the gas bubbles during charging and discharging can be minimized in this way and the mechanical stress and flexing movement on the coatings of the anode and cathode are also reduced and the risk of detachment is reduced. In addition, the electrically active surface is not interrupted by gas bubbles. Furthermore, this leads to a reduced crowning of the cell in the cell center. This in turn makes it possible to provide more homogeneous and reduced electrical aging.

To make this possible, there are several options, which will now be explained below.

3 shows a schematic representation of a cell chemistry unit 24a for a battery cell 26 (cf. 6 ) according to an embodiment of the invention. The cell chemistry unit 24 can also be used as follows 2 already explained, be constructed. For better description, the cell chemistry unit 24a is in 3 only shown in a very simplified manner and includes, as an example, two electrode layers, namely an anode layer 26 and a cathode layer 29, which are spatially and electrically insulated from one another by a separator layer 31. The anode layer has a carrier layer 33 in the form of an anode foil 33, which can be provided, for example, by a copper foil. An anode active material 35, which is also referred to as active material layer 35, is arranged on this carrier layer 33. This active material layer 35 is shown in 3 arranged below the anode foil 33. The cathode layer 29 accordingly also has a carrier layer 36, which can be provided as a cathode foil 36 and can be designed, for example, as an aluminum foil. A cathode active material in the form of an active material layer 38 is also arranged on this carrier layer 36, in this case above the carrier layer 36. The respective active material layers 35, 38 of the electrode layers 27, 29 therefore face each other and the separator. Furthermore, the anode layer 27 is arranged on an anode rail 40, in this case an anode copper rail 40, and is electrically connected to it, this copper rail 40 providing a negative pole of the battery cell, while the cathode layer 29 is electrically conductive to a cathode rail 42, in this example an aluminum rail 42, which provides a positive terminal of the cell. In general, the cell chemistry unit 24a can also have several such anode layers 27 and cathode layers 29, which are stacked one above the other in the x direction, in particular in an alternating order, with a separator layer 31 for electrical insulation always being arranged between two electrode layers 27, 29. The respective anode layers 27 can then be connected to a common anode rail 40, and accordingly also the cathode layers 29 to a common cathode rail 42.

In the present example, several grooves 44 are advantageously arranged in the cathode active material 38. These provide degassing channels 46, which make it possible to drain the gas 20 created in the cell, which is illustrated here by the arrows 20, from the center 32 of the cell chemistry unit into an edge region 34. Even if the individual electrode layers 27, 29 in the edge region 34 were pressed against one another due to the structural design of a cell housing, the degassing channels 46 provided would still provide an opportunity for the gas 20 to escape from the central region 32 into the edge region 34 to get to. The formation of large gas bubbles in the central area 32 can thus advantageously be avoided.

In this example, the grooves 44 introduced in the active material 38 run in a straight line, which simplifies production. In addition, several such grooves 44 can run either parallel to one another and/or in different directions and even overlapping. Furthermore, the grooves 44 can be, for example, as in 3 shown, at least partially also extend from a first edge region 34 to the edge region 34 opposite with respect to the z-direction. Although not shown here, these can also run from an edge region 34 to a further edge region 34 which is opposite with respect to the y-direction.

Furthermore, one or more such grooves 44 can be arranged not only in the cathode active material 38, but also analogously in the anode active material 35, although not shown here.

The grooves 44 can therefore be provided by channel-shaped compressions in the respective active material 35, 38, in particular already during the manufacturing process of the respective electrode layers 27, 29. For example, by scoring on the rollers by means of which the active material 35, 38 is applied to the respective carrier layer 33, 36, the active material can be locally more compacted during the rolling process.

4 shows a schematic representation of a cell chemistry unit 24b according to a further exemplary embodiment of the invention. In general, this cell chemistry unit 24b can again be as described above, in particular as described above 3 described, designed, except for the differences described below. In this example, the individual electrode layers 27, 29 are shown in an exploded view and without the separator 31 for better illustration. In this example too, degassing channels 46 are provided, which are now designed as slots 48 and no longer as grooves 44 in the active material 38, 35. As an example, such a slot 48 is provided in the anode layer 27 and in the cathode layer 29. Such a slot 48 completely penetrates the respective electrode layer 27, 29 in the x direction. In addition, such a slot 48 extends at least starting from a central area 32 to at least one of the edge areas 34. The edge areas 34 are illustrated in relation to the respective electrode layers 27, 29, but are also part of a corresponding edge area 34 of the cell chemistry unit 24b Whole.

The anode 40 and the cathode 42 do not necessarily have to be provided as rails as shown here, but can also be provided as part of the collector foils, for example as flags or tabs or similar. Such flags or tabs can, for example, also be formed integrally with the respective carrier film 33, 36 or manufactured separately and joined to the carrier films 33, 36.

Through these slots 48 it is now advantageously possible for gases 20 to get from a central area 32 to edge areas 34 much more easily. The slots 48 in layers which are arranged one above the other in the x direction are preferably offset from one another in the y direction and/or z direction. This can increase the stability of the overall structure. These slots 48 thus advantageously form degassing lanes in the anode and cathode foils 33, 36 or in the anode and cathode layers 27, 29.

5 shows a schematic exploded view of a cell chemistry unit 24c according to a further exemplary embodiment of the invention. This cell chemistry unit 24c can also be designed as described above, except for the differences described below. In this example, the respective electrode layers 27, 29 have neither grooves 44 nor slots 48, although these can of course also be provided, although not shown here, but additionally or alternatively a through opening 50 penetrating the cell chemistry unit 24c or its layers 28. This Through opening 50 is now provided by an opening 52 in the separator 31, as well as by respective openings 54 in the anode layer 27 and in the cathode layer 29 and its sub-layers, namely the anode carrier layer 33 and the anode active material layer 35, and on the other hand the cathode carrier layer 36 and the cathode active material layer 38. In the present example, the openings 54, 52 are arranged coaxially to one another, with a central axis being illustrated by line A. The opening 52 in the separator 31 is designed to be smaller, in particular in relation to its diameter, than the openings 54 in the anode layer 27 and the cathode layer 29. This can ensure that the anode layer 27 and cathode layer 29 are safely electrically insulated from one another. Through such a through opening 50, it is now advantageously possible for the gas 20 generated in the cell to escape from a central region 32, which can, for example, include the central axis A shown, into an edge region 34. However, this edge region 34 is not shown here, but, as previously defined, refers to the edge of the cell chemistry unit 24c in relation to the y-direction and/or z-direction. In the present example, the resulting gas 20 can, in a simplified manner, pave a path in or against the x direction through the individual layers 28, which also enables the gas 20 to reach the edge region of the cell chemistry unit 24c in a simplified manner. The through opening 50 can be provided in the form of a degassing hole in the center 32 of the cell or the cell chemistry unit 24c. The hole 50 in the separator film 31 can be made relatively small in order to effect degassing. The holes 54 in the anode 27 and cathode 29 are advantageously made larger in order to ensure the electrical insulation distance across the separator film 31. It should also be noted that in 5 the respective bore diameter is shown disproportionately for illustrative purposes.

Furthermore, it is additionally or alternatively also possible to carry out a structural redesign of the cell or module structure in order to prevent gas accumulation in the middle of the cell. This will now be explained in more detail below.

This shows 6 a schematic and perspective cross-sectional view of a battery cell 26 according to an exemplary embodiment of the invention. The battery cell 26 has a cell housing 56, which includes a cell interior 58. Inside the cell 58 there is a cell chemistry unit 24, 24a, 24b, 24c, which can be designed as described above. In the present example, the battery cell 26 is designed as a prismatic battery cell. The cell housing 56 has a first side 56a and a second side 56b that is opposite with respect to the x direction, which at the same time also represent the largest sides of the cell housing 56 in terms of area. These pages 56a, 56b now each have an expansion contour 60. This is formed all around a central area Z of the cell housing 56 with respect to the y and z directions. An edge region of the cell housing 56 is designated R. This expansion contour 60 can therefore directly adjoin the edge region R of the cell housing 56 with respect to the y and z directions. This expansion contour can be provided, for example, by a corrugated membrane. The edge region R of the cell 26 is therefore designed as a membrane 60 or with such a membrane 60 in order to prevent increased surface pressure in the edge region R of the cell 26. If the cell chemistry unit 24 expands in the x direction over the course of its service life, this leads to a movement of the side surface 56a, 56b in the central area Z, that is to say within the corrugated membrane 60, outwards, that is to say in and against the x direction. A curvature in and against the x-direction of these side surfaces 56a, 56b can thereby be avoided or its extent can be greatly reduced. This makes it easier for the resulting gas to get from the central area 32 of the cell chemistry unit 24 to the corresponding edge areas 34.

7 shows a schematic representation of a battery module 62 as an example of an energy storage arrangement according to an exemplary embodiment of the invention. In particular shows 7 the battery module 62 once in a new state N on the left and on the right after a certain service life L. The battery module 62 generally comprises a plurality of battery cells 26, which are arranged next to one another in the stacking direction x. Furthermore, the battery module 62 includes a clamping device 64, which in turn has two clamping plates 66, which limit the cell stack provided by the battery cells 26 in and against the x direction. There are also cell separating elements 68 between the respective battery cells 26. Such separating elements 68 can also be arranged between a respective end cell 26 and a pressure plate 66. In the present example, the pressure plates 66 are curved in the direction of the battery cells 26, at least in the new state N. This curvature 66a can be compensated for over the course of the service life by expanding the cells 26 in or against the x direction, as shown in 7 is shown on the right. Through this curvature 66a, which relates in particular to the z-direction and additionally or alternatively also to the y-direction, it can be achieved that the pressure distribution on the cells 26 can be modified in order to be in the cell center Z, which is only an example for a cell 26 is illustrated to generate an increased surface pressure. This means that a compressive force F1 comes from outside the cell housing 56 (cf. 6 ) via the cell housing 56 to the cell interior 58 (cf. 6 ) can be exercised, which in the central area of the cell housing 56 with respect to the z-direction, and in particular also to the y-direction, is greater than the compressive force F2 in an edge area of the cell housing. Due to the increased surface pressure, the gas is driven outwards from the center into the respective edge areas R. For reasons of clarity, only two of the edge regions R are illustrated as examples for only one battery cell 26.

8th shows a schematic representation of a battery module 62 according to a further exemplary embodiment of the invention. This is again in a new condition N on the left side and after a certain lifespan L on the right side 8th shown. Incidentally, this battery module 62 can also be used like this 7 be designed as described, except for the differences described below. In this example, the cell separating elements 68 are now bulged in the new state N. 8th shows on the left side the bulged cell separating elements 68 in the compressed cell mode 62, the compression or tensioning again being carried out by means of a tensioning device 64, as described above, except that here the pressure plates 66 do not necessarily have to be curved. Instead, the bulged cell separating elements 68 can now achieve an increased prestress in the cell center Z due to the convex cell separating elements 68. This also makes it possible for a clamping force F1 acting on the central area Z of the cells 26 to be greater than the force F2 acting in the edge area R. After a certain service life L, a state of the battery module 62 results as in 8th shown on the right. In this case, the cell separating elements 68 are now squeezed, due to the swelling of the battery cells 26. This also makes it possible to advantageously achieve that an increased surface pressure can be generated in the cell center Z, through which the gas can be driven outwards from the center.

Overall, the examples show how the invention can provide cell-internal degassing, through which the formation of flat gas bubbles between the layers of the cell can be minimized.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed 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.

Cited patent literature

• DE 102012018058 A1 [0003]

Claims (10)

Energy storage arrangement (62, 26) for a motor vehicle, wherein the energy storage arrangement (62, 26) comprises at least one battery cell (26), which has: - a cell interior (58); - a cell housing (56), which encloses the cell interior (58); and - a cell chemistry unit (24, 24a, 24b, 24c, 24d) arranged inside the cell (58); characterized in that the energy storage arrangement (62, 26) is designed to extract a gas (20) created in the cell interior (58) from a central area (32) of the cell chemistry unit (24, 24a) when the energy storage arrangement (62, 26) is in the intended operating state , 24b, 24c, 24d) in the direction of at least a first edge region (34) of the cell chemistry unit (24, 24a, 24b, 24c, 24d). Energy storage arrangement (62, 26). Claim 1 , characterized in that for discharging the gas (20) created inside the cell (58) from the central region (32) of the cell chemistry unit (24, 24a, 24b, 24c, 24d) in the direction of the at least one first edge region (34) of the cell chemistry unit (24, 24a, 24b, 24c, 24d) - the battery cell (26) has at least one degassing channel (46; 44, 48) arranged in the cell interior (58). Energy storage arrangement (62, 26) according to one of the preceding claims, characterized in that the cell chemistry unit (24, 24a, 24b, 24c, 24d) has a separator (31) and two electrode layers (27, 29) spatially separated from the separator (31). has, wherein a respective electrode layer (27, 29) has a carrier layer (33, 36) and an active material layer (35, 38) arranged on the carrier layer (33, 36), wherein the at least one degassing channel (46; 44, 48) is provided is, through - at least one groove (44) in at least one of the active material layers (35, 38); and/or - at least one slot (48) in at least one of the electrode layers (27, 29). Energy storage arrangement (62, 26) according to one of the preceding claims, characterized in that the cell chemistry unit (24, 24a, 24b, 24c, 24d) has a separator (31) and two electrode layers (27, 29) spatially separated from the separator (31). has, wherein a respective electrode layer (27, 29) has a carrier layer (33, 36) and an active material layer (35, 38) arranged on the carrier layer (33, 36), wherein the at least one degassing channel (46; 44, 48) at least is provided in part by - a through opening (which penetrates the two electrode layers (27, 29) and the separator (31), and in particular the entire cell chemistry unit (24, 24a, 24b, 24c, 24d), in a first direction (x). 50; 52, 54), which is provided by at least one first opening (52) in the separator (31), and at least one second opening (54) in each of the two electrode layers (27, 29), which is in the first direction ( x) are arranged overlapping, the at least one first opening (52) in the separator (31) being smaller than the respective at least one second opening (54) in the two electrode layers (27, 29). Energy storage arrangement (62, 26) according to one of the preceding claims, characterized in that for discharging the gas (20) created in the cell interior (58) from the central region (32) of the cell chemistry unit (24, 24a, 24b, 24c, 24d) in Direction of the at least one first edge region (34) of the cell chemistry unit (24, 24a, 24b, 24c, 24d) - the energy storage arrangement (62, 26) is set up such that with respect to a first direction (x) a compressive force (F1, F2) of outside the cell housing (56) via the cell housing (56) on the cell interior (58), which is larger in a central area (Z) of the cell housing (56) than in an edge area (R) of the cell housing (56). a second direction (y, z) perpendicular to the first direction (x). Energy storage arrangement (62) according to one of the preceding claims, characterized in that the energy storage arrangement (62) has a plurality of the at least one battery cell (26), the plurality of battery cells (26) being arranged next to one another in the first direction (x), with between two of the battery cells (26), which are arranged adjacent to one another in the first direction (x), a cell separating element (68) is arranged, which has less flexibility in a central area than in an edge area. Energy storage arrangement (62, 26) according to one of the preceding claims, characterized in that the energy storage arrangement (62, 26) has a cell stack comprising the at least one battery cell (26) and a clamping device (64) for clamping the cell stack in the first direction (x). has, wherein the clamping device (64) has two pressure plates (66) which delimit the cell stack on both sides with respect to the first direction (x), by means of which a compressive force can be exerted on the cell stack in the first direction (x), which is in a central area (32 ) of the cell stack is larger than in an edge region (34) of the cell stack in relation to the second direction (y, z) perpendicular to the first direction (x). Energy storage arrangement (62). Claim 7 , characterized in that at least one of the pressure plates (66) has an inner side surface facing the cell stack, which is curved in the direction of the cell stack. Energy storage arrangement (62, 26) according to one of the preceding claims, characterized in that at least a first side (56a, 56b) of the cell housing (56) of the at least one battery cell (26) has a central area (Z) and a central area (Z) around the central area ( Z) has a shot circumferential expansion contour (60) to reduce a curvature of the central region (Z) of the first side (56a, 56b) when expanding the cell chemistry unit (24, 24a, 24b, 24c, 24d) in the first direction (x), in particular, the expansion contour (60) adjoins an edge region of the first side (56a, 56b). Method for producing an energy storage arrangement (62, 26) with at least one battery cell (26), which has: - a cell interior (58); - a cell housing (56), which encloses the cell interior (58); and - a cell chemistry unit (24, 24a, 24b, 24c, 24d) arranged inside the cell (58); characterized in that the energy storage arrangement (62, 26) is manufactured in such a way that, in a normal operating state of the energy storage arrangement (62, 26), a gas (20) created in the cell interior (58) is released from a central area (32) of the cell chemistry unit (24, 24a, 24b, 24c, 24d) is derived in the direction of at least a first edge region (34) of the cell chemistry unit (24, 24a, 24b, 24c, 24d).

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