DE102019121720A1 - Method for testing or designing an electrical energy store - Google Patents

Abstract

A method for testing and / or designing an electrical energy store, comprising the steps of: providing a battery housing; arranging at least one expansion element in the battery housing; applying an internal pressure to the battery housing by means of the at least one expansion element.

Description

The present invention relates to a method for testing and / or designing an electrical energy store, an arrangement for testing and / or designing an electrical energy store, a use of an expansion element and an electrical energy store.

One focus here is in particular on lithium-ion cells. Due to their high power and energy density, these are widely used as electrochemical energy storage devices in mobile applications. The storage and retrieval of lithium ions and aging processes lead to volume change effects in the active materials. These lead to a change in thickness of the cell or an increase in force when the cells are pretensioned. In modules for electric vehicles, several cells are usually braced over a corresponding frame. The problem here is that, among other things, this results in loads that have a negative effect on the service life of the cells and their operating behavior.

It is therefore an object of the present invention to specify a method for testing and / or designing an electrical energy store, an arrangement for testing and / or designing an electrical energy store, a use of an expansion element and an electrical energy store so that in particular energy stores can be provided, which have an optimal operating behavior with a long service life.

This object is achieved by a method according to claim 1, by an arrangement according to claim 6, by a use according to claim 12 and by an electrical energy store according to claim 13. Further advantages and features emerge from the subclaims as well as the description and the attached figures.

• - Bereitstellen eines Batteriegehäuses;
• - Anordnen zumindest eines Expansionselements in dem Batteriegehäuse;
• - Aufbringen eines Innendrucks auf das Batteriegehäuse mittels des zumindest einen Expansionselements, insbesondere durch eine zumindest bereichsweise Druckbeaufschlagung mittels des Expansionselements oder auch durch eine Volumenvergrößerung des Expansionselements.

According to the invention, a method for testing and / or designing an, in particular electrical, energy storage device comprises the steps:

• - Provision of a battery housing;
• - Arranging at least one expansion element in the battery housing;
• Applying an internal pressure to the battery housing by means of the at least one expansion element, in particular by applying pressure at least in certain areas by means of the expansion element or also by increasing the volume of the expansion element.

According to a preferred embodiment, the energy store is an electrical energy store, in particular a lithium ion store. A large number of individual cells are typically configured into cell modules. During the production of these cell modules, the individual cells are pressed together with a defined force and kept in this state, for example by means of cell module frames. During the operation of the cells, among other things, when the cells are cycled (charging / discharging), so-called swelling forces arise inside the cells, the level of which depends on the state of charge and age. These forces or swelling forces press against the housing from the inside and, depending on the installation situation, cause the cells to bulge. Since the individual cells are held by the aforementioned frame, strong tension can arise, in particular if, for example, such a bulging of the cell (s) is not possible at all due to the geometrical or structural conditions. Damage to the cell or at least a reduction in life expectancy are very likely as a result. The use of the at least one expansion element represents an effective and effective approach to simulating the aforementioned forces, in particular swelling forces, in order to be able to optimally design the electrical storage device. As a result, the electrical energy storage device can be tested and / or designed in the best possible way, for example in a prototype or development phase. In particular, it is also a method for testing and / or designing a housing for an electrical energy storage device, such as, in particular, a lithium-ion cell. By increasing the volume of the expansion element, the battery housing can be acted upon from the inside with exactly the same forces as they would or would also result in real operation.

According to one embodiment, the increase in volume or the pressure in the expansion element is generated fluidically, in particular by introducing a fluid, liquid or gaseous, into the at least one expansion element.

According to a preferred embodiment, the at least one expansion element is a pressure pad. According to one embodiment, the pressure pad has a wall which is made of a textile and / or plastic material. Preferred materials are also rubber-like materials and / or rubber materials. At least in some areas, metallic materials or a mixture of the aforementioned materials can also be used for the wall. According to a preferred embodiment, the pressure pad is constructed and joined in several parts, for example at least two, three, four, five parts, the joining points or connection or contact points of the individual wall parts can be used to distribute a pressure acting in the expansion element differently on the battery housing.

• - Lokal unterschiedliches Aufbringen des Innendrucks.

According to one embodiment, the method comprises the step:

• - Locally different application of the internal pressure.

This takes into account the fact that the battery housing does not experience a uniform application of pressure and / or force from the inside in real operation, but that it is locally different.

• - Lokal unterschiedliches Aufbringen des Innendrucks über eine nur bereichsweise Anlage des Expansionselements am Batteriegehäuse.

According to one embodiment, the method comprises the step:

• - Locally different application of the internal pressure via an only area-wise contact of the expansion element on the battery housing.

This enables an exact and exact introduction of force into or onto precisely those areas of the battery housing which are actually subjected to pressure and / or force in real operation. According to one embodiment, simulation data are used, on the one hand, to determine the pressure in the expansion element, in which case a pressure profile over time can also advantageously be used, and, on the other hand, to precisely determine the locally different contact of the expansion element inside the battery housing.

• - Anordnen einer Vielzahl von Expansionselementen in dem Batteriegehäuse.

According to one embodiment, the method comprises the step:

• - Arranging a plurality of expansion elements in the battery housing.

This advantageously makes it possible, among other things, to achieve different pressures or pressure ranges. Depending on the geometry of the battery housing, the use of several expansion elements also enables the battery housing to be filled more easily with the expansion element.

The expansion element expediently completely fills the battery housing to be tested or designed. The battery housing is therefore preferably closed. In order to fill and / or empty the expansion element, the battery housing expediently has a corresponding opening or a corresponding recess. This is expediently provided with a valve. The expression “completely filled” does not mean that the wall of the expansion element must lie completely on the inside of the wall of the battery housing. As already mentioned, a better distribution of the forces or pressures prevailing during operation can be achieved through a targeted non-concern. Typical battery housing shapes in the present case are, for example, prismatic cells, round cells or pouch cells. Basically, the battery housings in question are in particular solid battery housings, in particular made of plastic and / or metal, such as aluminum. Electrical energy stores with flexible battery housings, such as pouch cells, etc., are also suitable for arranging such an expansion element.

The invention also relates to an arrangement or device for testing and / or designing an electrical energy store, in particular a battery housing, comprising at least one expansion element, arranged or mountable in a battery housing, as well as a pressure generation unit, whereby the battery housing is pressurized via the at least one expansion element can be. The pressure can in particular also be a pressure profile, that is to say a pressure curve with which the expansion element is acted upon over time. At this point it should be mentioned that the advantages and features mentioned in connection with the method apply analogously and correspondingly to the arrangement, and vice versa. According to one embodiment, the pressure generating unit is a suitable pump or a compressor. A gas, such as air, or a liquid, such as water or oil, can be used as the means for generating pressure.

The expansion element expediently has a wall, the wall being at least partially or completely flexible. This enables the wall to rest optimally on the inside of the battery housing, in particular regardless of its geometry.

According to one embodiment, the wall is designed to rest against the battery housing only in areas in the expanded state. The forces, pressures or swelling forces occurring during operation can expediently be optimally simulated. This area-wise system can also be implemented, inter alia, in that the wall is designed to be flexible only at least in areas.

According to one embodiment, the wall is locally reinforced and / or stiffened or precisely not flexible, as a result of which a shape of the wall can be set during expansion.

According to one embodiment, the aforementioned reinforcements or stiffeners are formed by seam and / or adhesive areas. Such a principle is known, for example, from air mattresses. A very good seal can be achieved through the combination of seams and glued joints become. In particular, the shape of the expansion element in the expanded state can be adjusted through the targeted introduction of seams. In this way, “chambers” can advantageously be formed.

Preferred pressures in the expanded state of the expansion element are in a range of approximately 6-12 bar. The aforementioned adhesive points or seams can, particularly preferably in combination, withstand these pressures. As already mentioned, the expansion element is preferably a pressure pad. This is preferably composed of a large number of individual parts or individual elements, it being possible to set a shape of the expansion element or the pressure pad, in particular in the expanded state, through this structure. The aforementioned seam or adhesive areas can in particular be used in addition to shaping.

According to one embodiment, the wall has at least regionally shaped elements, and the shaped elements are designed as projections and / or recesses. The shaped elements are expediently designed to enable an at least locally different introduction of pressure or force into the battery housing. According to one embodiment, the shaped elements are designed as knobs, grooves, webs or correspondingly designed recesses, whereby a force action on the battery housing from the inside can be simulated in a very targeted and local manner.

The invention is also directed to the use of an expansion element, in particular a pressure pad, for emulating or simulating pressures, in particular swelling forces, in a battery housing. The advantages and features mentioned in connection with the method and the arrangement apply analogously and correspondingly to the use or vice versa.

The invention is also directed to an electrical energy store, in particular a lithium-ion cell, for example with a prismatic battery housing or a cylindrical housing (round cell), or also designed as a pouch cell, which is designed or manufactured according to the method according to the invention.

Further advantages and features emerge from the following description of embodiments of the method or of arrangements for testing and / or designing an electrical energy store with reference to the attached figures. Different features can be combined with one another within the scope of the invention.

• 1: eine schematische Ansicht eines Batteriegehäuses sowie eines Expansionselements in einer Schnittansicht;
• 2: zwei Seitenansichten von Expansionselementen, von außen gesehen;
• 3: eine weitere Ausführungsform eines Expansionselements in einer Seitenansicht, sowie eine entsprechend skizzierte Schnittdarstellung,
• 4: zwei weitere Ansichten von Expansionselementen mit unterschiedlich angeordneten Klebe- bzw. Nahtbereichen;
• 5: eine weitere Ausführungsform eines Expansionselements mit Formelementen, von außen gesehen, wobei eine Wandung des Expansionselements mehrere Formelemente aufweist.

Show it:

• 1 : a schematic view of a battery housing and an expansion element in a sectional view;
• 2 : two side views of expansion elements, seen from the outside;
• 3 : Another embodiment of an expansion element in a side view, as well as a correspondingly sketched sectional view,
• 4th : two further views of expansion elements with differently arranged adhesive or seam areas;
• 5 : Another embodiment of an expansion element with shaped elements, seen from the outside, wherein a wall of the expansion element has several shaped elements.

1 shows a prismatic battery housing in a sectional view 10 , in which an expansion element is arranged. A wall can be seen here in particular 24 , wherein the aforementioned cut along a glue point 28 is carried out. There is also a seam in the area of the splice 30th arranged. This is shown as a dashed line. The expansion element can be through an opening in the battery housing 10 , for example by means of a valve 22nd , filled and / or emptied. It can be seen that the wall 24 completely inside the battery housing 10 is applied. As will be shown later, it is also possible to deviate from such a complete system, at least locally. With reference to the 2 two embodiments of expansion elements are now shown, which compared to the arrangement in FIG 1 rotated by 90 °. For better orientation, please also refer to the 1 and 2 referenced coordinate system.

2 shows two embodiments of expansion elements, as for example in the 1 are sketched. A battery case is not shown here. Compared to the orientation or arrangement in the 1 are the expansion elements in the 2 turned by 90 degrees. In the present case, in particular, the course of the glue point is intended 28 or the interface 30th it becomes clear which is formed circumferentially in the present embodiments. At the glue point 28 or at the interface 30th are a first wall part 25th and a second wall part 26th of the expansion element joined together overlapping. By combining gluing and sewing, high internal pressures can also be achieved, for example up to a range of 6-12 bar. It can be seen that the expansion elements, which are in the 2 are shown in the expanded state, have a different shape or geometry. This is due to the shape of the wall parts 25th or. 26th as well as through the splice 28 or interface 30th realized. As an alternative to the embodiments shown here, the seam can also be formed on the inside. The first part of the wall 25th and the second wall part 26th are sewn accordingly and then turned inside out so that only a slit can be seen on the outside.

3 shows a further side view of an expansion element with a wall 24 as well as a valve 22nd for filling. There are three glue points on the outside 28 , combined with seams 30th , arranged. To show their function and effect, a section is shown in the lower half of the picture. It can be seen that the arrangement or distribution of the adhesive points 28 or seams 30th leads to the fact that a kind of chamber profile is formed, as is known, for example, from air mattresses. As a result, a locally different introduction of force or pressure into the battery housing, cf. 1 , will be realized. Such shapes can also be achieved in that the wall element 24 is stiffened locally, for example by a different choice of material. As an alternative, such shapes can be realized by using a plurality of expansion elements. Appropriately, such shapes can also be achieved through the design of the wall 24 be realized themselves, in particular, for example, by a multi-part design of the wall 24 .

4th shows two further embodiments of expansion elements. The examples are intended to show that the splices 28 or seams 30th can be distributed very flexibly as required.

5 shows a further view of an expansion element with a wall 24 , with form elements on the outside 32 , in the embodiment shown here in the form of knobs, are arranged. These enable, among other things, a targeted or differentiated introduction of force into a battery housing, for example as in FIG 1 outlined.

List of reference symbols

10

Battery case

22nd

Valve

24

Wall

25th

first wall part

26th

second wall part

28

Glue point, glue area

30th

Seam, seam area

32

Form element

x, y, z

Coordinates

Claims (13)

A method for testing and / or designing an electrical energy store (10), comprising the steps: - providing a battery housing (10); - Arranging at least one expansion element in the battery housing (10); - applying an internal pressure to the battery housing (10) by means of the at least one expansion element. Procedure according to Claim 1 , wherein the at least one expansion element is a pressure pad. Procedure according to Claim 1 or 2 , comprising the step: - Locally different application of the internal pressure. Method according to one of the preceding claims, comprising the step: - Locally different application of the internal pressure via an only area-wise contact of the expansion element on the battery housing (10). Method according to one of the preceding claims, comprising the step: - Arranging a plurality of expansion elements in the battery housing (10). Arrangement for testing and / or designing an electrical energy store (10), comprising at least one expansion element, arranged or mountable in a battery housing (10), as well as a pressure generating unit, whereby the battery housing (10) can be subjected to pressure via the at least one expansion element. Arrangement according to Claim 6 , wherein the expansion element has a wall (24), and wherein the wall (24) is flexible at least in some areas. Arrangement according to Claim 7 , the wall (24) being designed to rest against the battery housing (10) only in areas in the expanded state. Arrangement according to one of the Claims 7 or 8th wherein the wall (24) is locally reinforced and / or stiffened, whereby a shape of the wall can be adjusted during expansion. Arrangement according to Claim 9 wherein the reinforcement (s) and / or stiffening (s) are formed by seams (30) and / or adhesive areas (28). Arrangement according to one of the Claims 7 to 10 , the wall (24) in some areas Has shaped elements (32), and wherein the shaped elements (32) are designed as protrusions and / or recesses. Use of an expansion element to simulate pressures, in particular swelling forces, in a battery housing (10). Electrical energy storage, designed according to a method according to one of Claims 1 - 5 .

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