Method and arrangement for detecting ageing of rechargeable battery cells

Abstract

A method for detecting ageing of rechargeable battery cells (1) which are combined in at least one stack and / or at least one row to form a module (2) or a battery. A temperature-control body (7) is inserted between two adjacent battery cells (1) such that it bears against the adjacent battery cells (1), wherein an outer casing (9) of the temperature-control body (7) is formed substantially from two planar contact elements (8a), (8b) which are connected directly or indirectly to one another circumferentially at the edge and enclose at least one fluid-conducting cavity (10) between them, and wherein at least one of the planar contact elements (8a), (8b) is deformable flexibly or elastically in such a way that it can give rise to an ageing-induced bulging of the adjacent battery cells (1) by reducing the volume of the fluid-conducting cavity (10). By detecting changes in volume of the fluid-conducting cavity (10) and evaluating the detected changes in volume with regard to ageing-induced bulging of the battery cells (1), the ageing of said battery cells can be detected.

Description

[0001] Method and arrangement for detecting aging of rechargeable battery cells

[0002] Description

[0003] The invention relates to a method for detecting the aging of rechargeable battery cells that are combined in a stack and / or a row to form a module or a battery. The invention also relates to an arrangement for carrying out this method.

[0004] A primary application area for the invention is rechargeable batteries in battery-electric vehicles. These are usually composed of a multitude of battery cells, which can be grouped into several modules. However, the invention can also be used in other fields of application, particularly in those where the required battery space for a certain storage capacity must be as small as possible, such as in stationary energy storage systems for photovoltaically generated electrical energy in buildings, especially residential buildings.

[0005] In these main application areas, there is typically only a narrow gap between the individual battery cells or modules, into which heat sinks are usually also inserted to dissipate the heat generated in the battery cells during charging and discharging. Thermal paste (gap filler) is commonly used to ensure optimal heat transfer between the battery cells or modules and the intervening heat sinks. This is not only due to the fact that the surfaces of the modules and battery cells to be cooled are often not flat: Conventional battery cells, especially those used in battery-electric vehicles, change their volume during charging and discharging; this is referred to as "breathing" of the battery cells.Accordingly, the gaps between the individual battery cells (and possibly also those between the individual modules) become narrower and wider with each charge-discharge cycle, with prismatic battery cells in particular bulging out on their broad sides as they increase in volume.

[0006] In WO 2022 / 069524 Al, a heat sink, more generally a temperature control element, as a cooling device for a rechargeable battery, is disclosed, the outer shell of which is essentially formed from two flat contact elements. These are connected to each other around their edges, enclosing a fluid-carrying cavity between them, which is provided with an inlet and an outlet. According to this prior art, the flat contact elements are each made of a single- or multi-layered film, in particular a plastic composite film. An important property of these films is their flexibility, which, when inserted into a gap between battery cells or modules, allows them to adapt to any unevenness, bulges, or movement of the battery cells or modules when fluid is flowing through them, thus establishing a thermally conductive contact over a large area without the need for gap fillers.

[0007] However advantageous the plastic film outer casing of the temperature control elements may be according to the current state of the art due to its shape-shifting capabilities, it does little to address the challenge that conventional battery cells age and, after reaching a lifespan that is usually related to the number of charging cycles completed but can vary individually from cell to cell, can generate significant heat that can lead to spontaneous combustion ("thermal runaway"). A major, as yet unresolved problem is the chain reaction that results, since after one battery cell ignites, its neighboring cells typically also catch fire. Naturally, this must be avoided, especially in applications in vehicles and buildings.

[0008] To prevent a chain reaction should a battery cell ignite or generate excessive heat, there are considerations to use flame barriers as propagation protection between the individual battery cells. However, these require additional installation space in the gap between the battery cells and can also impede heat transfer to a temperature control element located there.

[0009] The invention is therefore based on the objective of providing a method for detecting the aging of rechargeable battery cells and an arrangement for carrying out this method, so that the risk that a battery cell could be subject to an aging-related "thermal runaway" can be detected in time.

[0010] This problem is solved by a method having the features of claim 1 and by an arrangement having the features of claim 14.

[0011] Preferred embodiments of the method according to the invention are set out in claims 2 to 13. Advantageous further developments of the arrangement according to the invention are set out in claims 15 to 28.

[0012] In the method according to the invention, at least one temperature control element is inserted between two adjacent battery cells, whereby the temperature control element bears directly, or optionally also indirectly, against the adjacent battery cells. An outer shell of the temperature control element is essentially formed from two planar contact elements which are connected to each other directly or indirectly around their edges and enclose at least one fluid-carrying cavity between them. At least one of the planar contact elements is flexible or elastically deformable in such a way that it can yield to age-related bulging of the adjacent battery cells, thereby reducing the volume of the fluid-carrying cavity.

[0013] For the sake of readability, the following description of the invention refers only to a single fluid-carrying cavity of the temperature control element. However, it should be noted that, within the scope of the present invention, a temperature control element may also have more than one fluid-carrying cavity, and mentioning only one cavity does not preclude this.

[0014] The invention is based on the understanding that the deformability of the temperature control element, and thus also of its fluid-carrying cavity, is advantageous not only because it eliminates the need for gap fillers and compensates for volume changes in the battery cells, but also because the volume changes of the fluid-carrying cavity of the temperature control element are easy to detect and evaluate. In particular, a reduction in the volume of the fluid-carrying cavity is directly related to a bulging or volume increase of the adjacent battery cell. Since battery cells bulge or increase in volume over a longer period due to aging, this age-related bulging can also be easily distinguished from the "breathing" of the battery cell.

[0015] The arrangement according to the invention for carrying out the method accordingly comprises a temperature control element of the type described above, which is inserted between two adjacent battery cells in such a way that it bears directly or indirectly against the adjacent battery cells. Further essential elements of the arrangement are a measuring device for detecting volume changes of the fluid-carrying cavity and a data processing device for evaluating the detected volume changes with regard to age-related bulging of the battery cells. In a first embodiment, which is not accessible from the outside, the fluid-carrying cavity of the temperature control element used according to the invention is expediently filled with a gas so that it can change its volume. In this case, the detection of volume changes of the fluid-carrying cavity can be carried out by means of a pressure sensor and / or a motion sensor.Because if the volume of the fluid-carrying cavity changes, the pressure of the gas within it also changes. A motion sensor can be particularly useful if the flat contact elements of the temperature control element are not designed to be flexible; in such cases, the distance between the two flat contact elements can simply serve as a measure of the volume change in the fluid-carrying cavity.

[0016] However, it is particularly preferred within the scope of the present invention if the fluid-carrying cavity of the temperature control element is accessible from the outside via at least one inlet and at least one outlet through the outer shell. This allows it to be connected to a fluid circuit in order to fulfill its original purpose of temperature-controlling, i.e., generally cooling, the adjacent battery cells by means of a circulating temperature control fluid, preferably a water-glycol mixture. Battery cells, which typically heat up during charging and discharging, usually need to be cooled to an operating temperature at which they function optimally. In battery-electric vehicles, it may also be desirable or even necessary, depending on the situation, to bring the battery cells to an optimal or at least suitable operating temperature by heating them.

[0017] The use of a temperature control element whose fluid-carrying cavity is connected to a liquid circuit is particularly preferred within the scope of the present invention because the liquid circuit can be equipped with a defined liquid volume, so that it is sufficient to monitor the liquid volume and detect an increase in the liquid volume in the parts of the liquid circuit not belonging to the fluid-carrying cavity in order to recognize how much temperature control fluid is in the fluid-carrying cavity and / or how much temperature control fluid is displaced from it, for example by an aging-related bulging of the adjacent battery cells.The detected fluid volume in the parts of the fluid circuit not belonging to the fluid-carrying cavity is a direct measure of the volume of the fluid-carrying cavity of the temperature control element, and this in turn is directly related to the volume changes of the adjacent battery cells. As a result, an age-related bulging of the battery cells can be detected from the increase in fluid volume in the parts of the fluid circuit not belonging to the fluid-carrying cavity.

[0018] The change in fluid volume in the parts of the fluid circuit not belonging to the fluid-carrying cavity can be detected particularly advantageously at an expansion tank of this fluid circuit. If the fluid circuit is otherwise volume-stable, the fluid volume in the expansion tank is directly related to the fluid volume in the fluid-carrying cavity of the temperature control element. This means that only the fill level of the expansion tank, or alternatively a gas pressure in the expansion tank (provided it is gas-tight), needs to be detected to determine the current volume of the fluid-carrying cavity.In this way, for example, it is particularly easy to trigger an alarm message such as the illumination of a red warning light when the filling volume of the expansion tank reaches or exceeds a maximum value that indicates a degree of bulging of the battery cells, which gives concrete cause to fear an impending thermal runaway.

[0019] Besides the primary advantage of the invention, namely the ability to detect age-related bulges in the monitored battery cells, the inventive method and the corresponding system can also advantageously be used to detect and evaluate charge cycle-related volume changes in the battery cells, and in particular to determine the number of charge cycles the battery cells have undergone. For this purpose, it may be sufficient, for example, to detect volume flows in the fluid circuit to or from a reservoir and to evaluate their flow direction and the number of changes in flow direction with regard to charge cycle-related volume changes in the battery cells.Especially for battery electric vehicles, which are not only traded in new condition but for which there is a used market, the number of charging cycles performed is an important value-determining factor for the rechargeable battery and thus also for the entire battery electric vehicle.

[0020] The present invention can be implemented using temperature control elements such as those known from the aforementioned WO 2022 / 069524A1. However, the thermal conductivity of the plastic films used as planar contact elements is not optimal, and the low mechanical resistance of the plastic films can also be problematic in the manufacture of the rechargeable battery.

[0021] Within the scope of the present invention, it is therefore particularly preferred to use a temperature control element whose planar contact elements consist of a metal plate or a planar molded part made of metal, in particular stainless steel (preferably material number 1.4404), the material thickness of which is selected in relation to its planar extent or in relation to the extent and shape of the fluid-carrying cavity or cavities such that the outer shell of the temperature control element is subjected to a negative pressure in a range of 100 mbar to 700 mbar, preferably 400 mbar to 600 mbar, by pressurizing the fluid-carrying cavity.with a rough vacuum, or with overpressure in a range of 0.5 bar to 10 bar, preferably 0.5 bar to 1.5 bar, and subsequently returns essentially to its original shape by the elastic restoring force inherent in the metal and / or by an elastic restoring force of a spring element provided in the fluid-carrying cavity.

[0022] The use of metal plates or flat metal components as flat contact elements forming the outer shell of the temperature control element has several significant advantages over the aforementioned prior art, according to which plastic or plastic composite films are used as flat contact elements:

[0023] Metal surfaces are inherently more mechanically resistant than plastic surfaces, which simplifies handling during battery module assembly, particularly when inserting temperature control elements between two modules. Furthermore, metallic materials generally have good thermal conductivity, whereas plastics tend to have heat-insulating properties; however, the thermal conductivity of the outer shell is a crucial characteristic for a temperature control element. The recyclability of metals is superior, and their long-term stability is virtually unmatched by plastics, especially in battery-electric vehicles, which must operate reliably across a very wide temperature range. Moreover, the vehicle's movement generates relative motion within the battery and corresponding friction between the contacting surfaces.

[0024] It is particularly advantageous that the preferred temperature control element, whose outer casing is made of metal on at least one side, is fire-resistant and can therefore effectively delay or even prevent a fire originating in one of the battery cells from spreading (propagation) across the battery. Even in the event of thermal runaway or spontaneous combustion of a battery cell, the cooling effect of the temperature control element is not lost, which, in addition to its fire-resistant properties, ensures additional protection against propagation.

[0025] Due to the choice of the (small) material thickness of the metal plate or the flat metal molded part, such a preferred temperature control element can be very easily inserted into a gap between two battery cells or modules, particularly when the fluid-carrying cavity is evacuated with a rough vacuum and the outer shell is thereby elastically deformed. The clear gap width of this gap is approximately equal to or less than the original height of the outer shell of the temperature control element. Subsequent ventilation of the fluid-carrying cavity causes the outer shell of the temperature control element to elastically deform back, thereby making contact over a large area with the adjacent battery cells or modules, or with at least one battery cell or module. This is the case even if the surfaces of the battery cells or modules are not flat.

[0026] The large contact area with the adjacent battery cells or modules naturally offers advantages with regard to the temperature control function of the temperature control element, because the larger and closer the heat-conducting contact between the temperature control element and the adjacent battery cell or module, the more efficient the desired heat transfer.

[0027] The close contact of the elastically deformable temperature control element with adjacent battery cells or modules is also highly advantageous because it provides a spring-like fixation between the battery cells or modules. Due to the aforementioned "breathing" behavior of battery cells during charging and discharging, as well as age-related warping, gaps or expansion joints must remain between the individual battery cells. However, these gaps, especially during the operation of battery-electric vehicles with their typical movements and vibrations, can cause the battery cells to move relative to each other and, in the worst case, collide, causing rattling noises or even damage.The temperature control elements preferably used within the scope of the present invention prevent this by forming a kind of spring cushion due to their elastic deformability, which springs together the adjacent battery cells or modules.

[0028] The insertion of the temperature control element between two adjacent battery cells or modules can be done in two ways:

[0029] In a first embodiment of the inventive method developed in this way, a stack of at least two battery cells or modules, arranged in a fixed position relative to one another, is first provided, and a plane-parallel or contoured gap with a predetermined clear gap width is left between them. The temperature control element, which is to serve as an intermediate layer, is selected such that its height, viewed in the direction of a mean surface normal of the planar contact elements, essentially corresponds to the clear gap width or is preferably greater than this gap width. In order to be able to insert the temperature control element between the two adjacent battery cells or modules, its fluid-carrying cavity is subjected to a vacuum in the range of 100 mbar to 700 mbar, preferably 400 mbar to 600 mbar, so that the height of the temperature control element changes due to elastic deformation of its outer shell, i.e.,The pressure of at least one of the first two planar contact elements is reduced and is therefore less than the clear gap width. In this state, the cooling element can be inserted into the gap. Subsequently, the negative pressure is removed, for example by simply venting the fluid-carrying cavity, so that the elastic deformation of the first planar contact element or of the two contact elements of the cooling element is substantially reversed by its or their inherent elastic restoring force and / or by at least one spring element arranged in the fluid-carrying cavity, and the outer shell of the cooling element thereby conforms to the adjacent battery cells or modules, preferably with preload, in order to establish a thermally conductive contact and / or to resiliently fix the battery cells or modules.

[0030] Optionally, the fluid-carrying cavity of the temperature control element can also be pressurized to a pressure in the range of 0.5 bar to 10 bar, preferably 0.5 bar to 1.5 bar, so that any residual plastic deformations are eliminated and / or to optimize the contact of the outer shell with uneven module or battery cell surfaces. Pressurizing the fluid-carrying cavity of the temperature control element is particularly preferred when the gap is not perfectly parallel to the surface but has areas with a larger gap width than the clear gap width, for example, in undercut areas.

[0031] In a second variant, a stack of at least two battery cells or modules is provided, between which a temperature control element is pre-positioned, in contact with the adjacent battery cells or modules. The battery cells or modules are then clamped against each other, for example, using a clamping frame, by moving them towards each other against the elastic restoring force of the temperature control element's outer shell until the outer shell, due to its elasticity, optionally with the aid of pressurizing the fluid-carrying cavity, presses against the adjacent battery cells or modules to establish the desired thermally conductive contact. This method is particularly suitable for modules with contoured surfaces, preferably using a correspondingly contoured molded part as the surface contact element of the temperature control element.

[0032] The first planar contact element of the preferred temperature control element has a material thickness of less than 1 mm, preferably less than or equal to 0.1 mm, to ensure the properties according to the invention, particularly when stainless steel, preferably with the aforementioned material number or an equivalent material, is used. It has been shown that, for typical dimensions of rechargeable batteries consisting of a battery cell or module stack used in battery-electric vehicles, a material thickness of the outer shell of the temperature control element according to the invention of slightly less than 0.1 mm is optimal with regard to the properties according to the invention, as well as with regard to robustness, fire resistance, and an advantageously low overall height of the temperature control element, typically less than 4 mm, while still providing sufficient heat dissipation.

[0033] The fluid-carrying cavity of the preferred temperature control element is particularly preferably designed as a meandering channel between the at least one inlet and the at least one outlet. This ensures that the temperature control element is permeated by the fluid at the most uniform velocity possible across its surface, preventing the formation of areas where the fluid flow is reduced. Simultaneously, a meandering channel can generate turbulence in the fluid flow, which ensures better heat transfer from the module surface to be tempered into the fluid, as the fluid is continuously mixed as it flows through the cavity.

[0034] To enhance or selectively influence the mixing effect of the fluid in the fluid-carrying cavity, thereby optimizing the heat distribution in the flowing fluid and consequently the heat transfer from the fluid to the module or vice versa, it is also particularly preferred within the scope of the invention, regardless of the shape of the fluid-carrying cavity, if it is equipped with flow-influencing elements for generating or enhancing turbulent flow behavior of a fluid flowing through the cavity, wherein these flow-influencing elements are preferably formed into at least the first planar contact element. Forming can be carried out in particular by embossing, for example, stamping, which is a particularly efficient forming technique for metal sheets.A major advantage of molded-in, flow-influencing elements can also be that they can prevent the fluid-carrying cavity from collapsing during evacuation.

[0035] In order to achieve a simple and cost-effective manufacturing process for the temperature control element according to the invention, it is preferred if the outer shell of the temperature control element is formed essentially from two thin-walled metal plates, preferably less than 1 mm thick, and more preferably less than or equal to 0.1 mm thick, made from blanks, in particular stainless steel blanks, as planar contact elements. These plates are joined to each other around their edges by welding, soldering, or bonding and enclose a fluid-carrying cavity between them. The metal plates can, for example, be prepared in a drop forging process such that they enclose, for instance, a meandering channel as the fluid-carrying cavity between them.

[0036] This preferred embodiment of a temperature control element also preferably features an imprinted structure in its thin-walled metal plates for influencing the flow of a fluid that flows from the inlet to the outlet through the fluid-carrying cavity. Here, too, the imprinted structures can also serve to prevent the fluid-carrying cavity from collapsing during evacuation. Advantageously, the imprinted structure can be formed into the thin-walled metal plates simultaneously with the formation of the fluid-carrying cavity by forming, in particular cold forming, for example in a drop forging process.

[0037] In this preferred embodiment of the temperature control element, whose outer shell essentially consists of two thin-walled metal plates, the inlet and outlet (or multiple inlets and outlets) comprise at least one inlet nozzle and at least one outlet nozzle, each of which is soldered, welded, or bonded to an opening in one of the thin-walled metal plates, or which is inserted at the edge junction of the thin-walled metal plates and soldered, welded, or bonded in place, depending on the desired flow conditions or the installation situation. Inlet and outlet nozzles whose axes run essentially parallel to the central plane of the temperature control element offer the advantage of minimal flow resistance.

[0038] Within the scope of the present invention, a plurality of temperature control elements can be used in a rechargeable battery. These can be interconnected, for example, by means of metal hoses, in particular corrugated hoses, or Meta II bellows. The metal hoses or bellows can be attached to the inlets and / or outlets of the temperature control elements, so that the fluid flows through them, in particular in series.

[0039] This design is particularly easy to manufacture, requires minimal installation space, and, thanks to the flexibility of the metal tubes or bellows, ensures an exceptional service life even when the battery is located in a battery-electric vehicle, is subject to movement and vibration during operation, and the assembly is subject to temperature-related expansion. Furthermore, this design allows for the implementation of the preferred method in which the temperature control elements are first inserted between the battery modules and the modules are then clamped against each other, naturally reducing the distance between the individual temperature control elements.

[0040] Alternatively, a supply pipe and a return pipe can be provided, which interconnect a multitude of temperature control elements. The temperature control elements are connected to the supply pipe via metal hoses, in particular corrugated hoses, or metal bellows attached to the inlets of the temperature control elements, and to the return pipe via metal hoses, in particular corrugated hoses, or metal bellows attached to the outlets of the temperature control elements. The metal hoses or bellows can be attached to the inlets and / or outlets of the temperature control elements using quick-release couplings, allowing the temperature control elements to be initially inserted as intermediate layers between the battery cells or modules and then easily connected to the supply and outlet pipes.

[0041] In this second variant, the individual temperature control elements are arranged in parallel from a fluid dynamics perspective, meaning the fluid flows through them in parallel rather than successively in series. This is advantageous for applications where the fluid temperature changes significantly during operation due to heat transfer to and from the modules.

[0042] The present invention thus provides a method and an arrangement for carrying out the method, which offers protection against thermal runaway between individual battery cells or modules of a rechargeable battery. This is achieved by an integrated temperature control element that forms a flame barrier, as it consists of metal plates and is permeated by a cooling fluid. Simultaneously, the temperature control elements ensure sufficient preload between the individual battery cells or modules to hold them resiliently in place and, in particular, to prevent movement noise. They also allow the battery cells to "breathe" and compensate for the increase in volume of the battery cells with age, optionally even with constant restoring forces. Above all, the invention enables the proactive detection of potential thermal runaway of battery cells by monitoring their age-related volume increase.

[0043] To illustrate the present invention, drawings are included in which exemplary embodiments of an arrangement for carrying out the method according to the invention are shown, and with reference to which the method is also explained below by way of example. The drawings and the described exemplary embodiments limit the scope and significance of the preceding description of the

[0044] The invention and the patent claims do not include, but may contain further features essential to the invention.

[0045] They show:

[0046] Figure 1 shows a series of interconnected battery cells in their new and aged states;

[0047] Figure 2 is a diagram illustrating the charging cycle-related breathing and the aging-related thresholding of rechargeable battery cells;

[0048] Figure 3 shows a temperature control element for use in the inventive method and arrangement in a horizontal sectional view;

[0049] Figures 4a / b show vertical sectional views of a part of the temperature control element from Figure 3 in its initial state and in an elastically deformed state;

[0050] Figures 5a / b / c show the insertion of a temperature control element into a gap between two

[0051] Battery cells;

[0052] Figure 6 shows a stack of battery cells with interposed temperature control elements and a liquid circuit;

[0053] Figure 7 shows a temperature control element as in Figure 3, but in a different embodiment; Figures 8a / b show a schematic illustration of a method for clamping a temperature control element between battery cells or modules of a battery.

[0054] The figures are schematic representations and are neither to scale nor proportionate to the dimensions shown. In particular, the height of the temperature control unit has been exaggerated for illustrative purposes. Spatial orientations are also only shown as examples.

[0055] Figure 1 schematically shows four battery cells 1, in their new state on the left and in their aged state on the right, which are connected to form a module 2 of a battery. The battery cells 1 are located in a frame (not shown) that essentially holds them in a fixed position. A gap 3 is located between each individual battery cell 1 to allow for changes in volume. This is because they "breathe" during charging cycles, i.e., they bulge slightly and then essentially return to their original shape.

[0056] Column 3 is therefore typically filled with compressible materials (not shown) to prevent noise generation caused by the individual battery cells striking each other, particularly during vehicle use involving impacts and vibrations. Alternatively or additionally, flame-retardant barriers (not shown) can be inserted into column 3 to prevent a thermally perforated battery cell from causing a chain reaction in module 2. It is also known to insert heat sinks or temperature control elements into column 3 to maintain the battery cells 1 within an optimal temperature range during both charging and discharging. However, prior to the present invention, these three functions could not be implemented simultaneously, or only with considerable effort.In the right half of Figure 1, module 2 from the left half is shown in an aged state. With each charging cycle, the battery cells 1 no longer fully return to their original shape, but gradually bulge outwards, so that the degree of bulging is a measure of the aging of the battery cells and can be used, among other things, to determine when the risk of thermal runaway is no longer negligible or is even imminent.

[0057] This is illustrated by the diagram in Figure 2, which plots the cell thickness against the number of charge cycles: Starting with a new cell thickness 4, the battery cell "breathes" with each charge cycle, with the average cell thickness increasing as the number of charge cycles increases. Thus, there is a thickness change amplitude 5 of the battery cell, which, upon reaching a lifetime cell thickness 6, indicates the end of the battery cell's lifetime, as continued operation of the battery cell then carries the risk of thermal runaway.

[0058] Figure 3 is a schematic top view of an embodiment of a temperature control element 7, as used in a method and arrangement according to the invention for carrying out this method, and which can be inserted into the gap 3 between two battery cells 1. The temperature control element 7, which is shown schematically here in a horizontal sectional view along its plane of extension, consists of two thin-walled stainless steel plates with a material thickness of 0.1 mm, which form an outer shell 9 of the temperature control element 7 as a first planar contact element 8a and a second planar contact element 8b (omitted here due to the sectional view), which are connected to each other around their edges by welding.

[0059] By appropriately shaping the two flat contact elements 8a, 8b through stamping and embossing, a fluid-carrying cavity 10 is formed inside the outer shell 9. In this embodiment, this cavity meanders from an inlet 11a inside the temperature control body 7 to an outlet 11b. A temperature control fluid 12 can be introduced into the fluid-carrying cavity 10 through the inlet 11a and is then discharged from the temperature control body 7 through the outlet 11b.

[0060] In the stamping and embossing of the planar contact elements 8a, 8b, in which the fluid-carrying cavity 10 was formed, a number of nubs 13 were also introduced in the present embodiment of a temperature control body 7, which structure the wall of the fluid-carrying cavity 10 and thereby, on the one hand, generate flow turbulence in the temperature control fluid 12 and thereby optimize the heat transfer between the temperature control fluid 12 and the planar contact elements 8a, 8b, and on the other hand, prevent the planar contact elements 8a, 8b from coming into large-area contact with each other when the fluid-carrying cavity 10 is evacuated and the fluid-carrying cavity 10 from collapsing as a result.For the fluid-carrying cavity 10 can be evacuated or pressurized with a gas pressure above normal pressure via the inlet 11a and the outlet 11b, especially as long as it has not yet been filled with a temperature control fluid, as illustrated below with reference to Figures 4a and 4b as well as Figures 5a to 5c.

[0061] Figures 4a and 4b schematically show a cross-sectional view of a portion of the temperature control element 7 from Figure 1, with the section perpendicular to the plane of extension of the temperature control element 7. The two flat contact elements 8a, 8b (exaggerated in their material thickness and height) are joined together, connected around their edges, and thus form the outer shell 9 of the temperature control element 7 and the fluid-carrying cavity 10. Only two sections of the fluid-carrying cavity 10 are shown as examples. Nubs 13 are incorporated into each flat contact element 8a, 8b, which, in addition to influencing the flow of liquid through the fluid-carrying cavity 10, in particular prevent its collapse when the outer shell 9 is deformed by evacuation; this is shown in Figure 4b. In this case, the flat contact elements 8a, 8b were formed from stainless steel sheets.The material thickness of the stainless steel plates was selected based on the expansion of the fluid-carrying cavity 10 and the shape of the planar contact elements 8a, 8b, such that a mechanical stress is generated when the temperature control element 7 is deformed. For example, the material thickness can be 0.1 mm for typical battery cells, which are used particularly in battery-electric vehicles.

[0062] Figure 4a shows the temperature control element 7 at normal pressure in the fluid-carrying cavity 10. In this example, the contour shown corresponds to the original shape of the temperature control element 7. Elastic deformation can occur, for example, if the fluid-carrying cavity 10 is initially subjected to overpressure or underpressure. During such deformation, mechanical stress arises in the temperature control element 7 due to the selected material, the material thickness, the expansion, and the shape of the outer shell 9 and the fluid-carrying cavity 10. Upon a return to normal pressure, the temperature control element 7, or rather its outer shell 9, resumes its original shape due to the mechanical stress.

[0063] Figure 4b shows the temperature control element 7 when a vacuum is applied to the fluid-carrying cavity 10. The vacuum causes the fluid-carrying cavity 10 to contract, thus thinning the temperature control element 7. This is an elastic deformation, resulting in a mechanical stress that counteracts the vacuum. In addition to this mechanical stress, the nubs 13 incorporated into the outer shell 9 also counteract the vacuum and prevent the fluid-carrying cavity 10 from collapsing. When normal pressure is restored in the fluid-carrying cavity 10 by venting, the temperature control element 7 returns to its original shape, as shown in Figure 4a, due to the mechanical stress.

[0064] This elastic deformation behavior of the embodiment for a temperature control element 7 shown in Figures 3, 4a and 4b enables a preferred insertion of the temperature control element 7 into the gap 3 between two battery cells 1 or modules, as shown in the schematic representations of Figures 5a, 5b and 5c:

[0065] Two battery cells 1 (or modules 2) are arranged at a predetermined distance from each other, leaving the gap 3 between them. A temperature control element 7 with a height 14 wider than the gap 3 is provided, as shown in Figure 5a, and its fluid-carrying cavity 10 is connected to a vacuum pump (not shown) via a connection port 15 at the inlet and / or outlet. Evacuating the fluid-carrying cavity 10 deforms the outer shell 9 of the temperature control element 7, reducing its height 14 until it is narrower than the gap 3. This is illustrated in Figure 5b. The temperature control element 7 can then be easily inserted into the gap 3 between the battery cells 1.

[0066] Figure 5c shows the situation after the temperature control element 7 has been inserted into the gap 3 and the fluid-carrying cavity 10 has been vented again. As a result, the outer shell 9 of the temperature control element 7 has deformed back towards its normal state due to its elastic restoring force, although the adjacent battery cells 1 limit this deformation. The height of the temperature control element 7 is now equal to the width of the gap 3, and the two planar contact elements 8a, 8b are in contact with the battery cells 1 under preload. This ensures excellent heat transfer between the temperature control fluid 12 circulating through the fluid-carrying cavity 10 and the battery cells 1. Furthermore, the temperature control element 7 also preloads the battery cells 1 against each other, thus holding them resiliently in place.Finally, the elastic deformability of the outer shell 9 of the temperature control body 7 allows the battery cells 1 to bulge out during breathing in the charging cycles and due to an aging-related increase in volume without being damaged.

[0067] Figure 6 now shows a stack of four battery cells 1, between each of which a

[0068] Temperature control elements 7 are located, preferably inserted into the gap 3 between the battery cells 1 using a method according to Figures 5a to 5c. These temperature control elements 7 are connected to a liquid circuit 16, which is only shown schematically here. It essentially consists of a supply pipe 17a, which is connected to the inlets 11a of all temperature control elements 7, a return pipe 17b, which is connected to the outlets 11b of all temperature control elements 7, a heat exchanger 18, a pump 19, and an expansion tank 20, which is monitored by a measuring device 21. This measuring device is in turn connected to a data processing unit 23 via a data line 22.

[0069] In this embodiment of an arrangement according to the invention, the temperature control elements 7 are circulated in parallel with the temperature control fluid 12, which is circulated by the pump 19 and brought to the desired temperature in the heat exchanger 18. The fluid circuit 16 contains a defined fluid volume, and the fluid-conducting parts, with the exception of the temperature control elements 7, are dimensionally stable at the temperatures and pressures prevailing during operation. Therefore, if the fluid-conducting cavities 10 of the temperature control elements 7 deform due to a change in the volume of the battery cells 1 (or even just one battery cell 1), the filling volume of a fluid component 24 present in the expansion tank 20 changes, and consequently, so does the gas pressure of a gas 25 located in the expansion tank 20.Both the fill volume of the liquid component 24 and the gas pressure can be detected by the measuring device 21, which allows the data processing unit 23 to infer the volume change of the fluid-carrying cavities 10 of the temperature control elements 7. This, as mentioned, is a measure of the volume change of the battery cells 1, whether due to "breathing" during charging cycles or due to aging-related bulging.

[0070] The periodic fluctuations of the parameters detected by the measuring device 21 can also be counted to determine the number of charging cycles completed by the battery cells 1. The amplitude of these periodic fluctuations can also be used to resolve partial charge cycles, meaning that, if necessary, it can be determined how far the battery cells were discharged and / or charged in each case.

[0071] Figure 7 shows, in a representation similar to Figure 3, another embodiment of a temperature control element 7. This temperature control element 7 also consists of two thin-walled stainless steel plates with a material thickness of 0.1 mm, which form the outer shell 9 of the temperature control element 7 as a first flat contact element 8a and a second flat contact element 8b (omitted for the sectional view), joined around their edges. The fluid-carrying cavity 10, bounded by the two flat contact elements 8a and 8b, this time completely fills the space within the outer shell 9; it does not form a meandering channel as in the embodiment shown in Figure 3. Here, too, temperature control fluid 12 can be introduced into the fluid-carrying cavity 10 through the inlet 11a and discharged again through the outlet 11b.

[0072] This embodiment is also suitable for connection to a liquid circuit. However, it is also suitable for being filled with a gas and then sealed in order to detect, by means of a pressure sensor 26 (only indicated here), a change in the volume of the fluid-carrying cavity, from which changes in the volume of the adjacent battery cells 1 can be inferred. In this case, the temperature control element can hardly regulate the temperature of the adjacent battery cells; however, its functions according to the invention—to detect volume changes with regard to age-related bulging of the battery cells and to simultaneously provide protection against propagation—remain intact.

[0073] An embodiment of a further development of the method according to the invention, in which several temperature control elements 7 are inserted between battery cells 1 (or modules 2) and hydraulically connected to one another, is schematically illustrated in Figures 8a and 8b: Figure 8a shows several temperature control elements 7 that have been inserted between the battery cells 1 of a battery. Here, normal pressure prevails in the fluid-carrying cavities 10 of the temperature control elements 7, so that the temperature control elements 7 are in their original shape. Alternatively, the fluid-carrying cavities 10 of the temperature control elements 7 can be pressurized, so that their respective height 14 is less than in their original shape, or alternatively, they can be pressurized to increase their elastic restoring force against compression. The battery cells 1 are not yet in contact with the temperature control elements 7 in this figure.It is also possible that they are in contact, but not firmly clamped against each other.

[0074] In the subsequent step, shown in Figure 8b, the battery cells 1 and the temperature control elements 7 are clamped against each other, which is achieved here by means of a clamping frame 27. The inherent restoring force of the temperature control elements 7, which may be increased by overpressure, counteracts the external clamping force, so that the fluid-carrying cavities 10 of the temperature control elements 7 do not collapse.

[0075] In this embodiment, the temperature control elements 7 are fluidically connected to one another by metal bellows 28, each of which is attached on one side to the inlet 11a of one temperature control element 7 and on the other side to the outlet 11b of an adjacent temperature control element 7, thus fluidly connecting these two adjacent temperature control elements 7. The metal bellows 28 are axially movable, so that they are not damaged during the clamping of the battery cells 1 as described above.

[0076] Reference symbol list:

[0077] 1 battery cell, 15 connection spigots

[0078] 2 Module 16 Liquid Cycle

[0079] 3 gap 17a supply pipe

[0080] 4 New cell thickness 17b Return pipe

[0081] 5 Thickness change amplitude 18 Heat exchangers

[0082] 6 Lifetime cell thickness 19 Pump

[0083] 7 temperature control elements 20 expansion tanks

[0084] 8a, 8b Surface contact elements 21 Measuring device

[0085] 9 Outer casing 22 Data line

[0086] 10 Fluid-carrying cavity 23 Data processing unit

[0087] 11a Inlet 24 Liquid content

[0088] 11b Expiry 25 Gas

[0089] 12 Temperature control fluid 26 Pressure sensor

[0090] 13 studs 27 tension frames

[0091] 14 Construction height (of 7) 28 Metal bellows

Claims

34 AMENDED CLAIMS received by the International Bureau on 14 November 2025 (14.11.2025) 1. Method for detecting aging of rechargeable battery cells (1) which are combined in at least one stack and / or at least one row to form a module (2) or a battery, comprising the following method steps: Inserting at least one temperature control element (7) between two adjacent battery cells (1), wherein the temperature control element (7) bears directly or indirectly against the adjacent battery cells (1), wherein an outer shell (9) of the temperature control element (7) is essentially formed from two planar contact elements (8a, 8b) which are directly or indirectly connected to each other around their edges and enclose at least one fluid-carrying cavity (10) between them, and wherein at least one of the planar contact elements (8a, 8b) is flexible or elastically deformable in such a way that it can yield to an age-related bulging of the adjacent battery cells (1) by reducing the volume of the fluid-carrying cavity (10), Detecting volume changes of the fluid-carrying cavity (10), and evaluating the detected volume changes with regard to age-related bulging of the battery cells (1).

2. Method according to claim 1, wherein the fluid-carrying cavity (10) is filled with a gas under a predetermined pressure and the detection of volume changes of the fluid-carrying cavity (10) is carried out by means of a pressure sensor (26) or a motion sensor.

3. The method according to claim 1, wherein a temperature control element (7) is used, the fluid-carrying cavity (10) of which is accessible from the outside through the outer shell (9) via at least one inlet (11a) and at least one outlet (11b), comprising the following additional method steps: Connecting the fluid-carrying cavity (10) of the temperature control element (7) to a liquid circuit (16) with a defined liquid volume, AMENDED SHEET (ARTICLE 19) 35 Monitoring the fluid volume and detecting an increase or change in the fluid volume in the parts of the fluid circuit (16) that do not belong to the fluid-carrying cavity (10) in order to detect and evaluate the volume changes of the fluid-carrying cavity (10).

4. Method according to claim 3, wherein a liquid circuit (16) with a compensating reservoir (20) is used and volume changes of the liquid volume are detected by measuring the filling volume of the liquid fraction (24) present in the compensating reservoir (20) or by measuring a gas pressure in the compensating reservoir (20).

5. Method according to at least one of claims 1 to 4, wherein the detected volume changes of the fluid-carrying cavity (10) are evaluated with regard to charge cycle-related bulges of the battery cells (1) and are used in particular to determine the number of charge cycles undergone by the adjacent battery cells (1).

6. Method according to claim 3 or 4, wherein volume flows in the liquid circuit (16) to and from the expansion tank (20) or to and from the temperature control body (7) are detected and their flow direction and the number of changes in flow direction with regard to charge cycle-related bulges of the battery cells (1) are evaluated and used to determine the number of charge cycles undergone by the adjacent battery cells (1).

7. Method according to at least one of claims 1 to 6, wherein the liquid circuit (16) is used for temperature control, in particular cooling, of the battery cells (1) adjacent to a temperature control element (7).

8. Method according to at least one of claims 1 to 7, wherein a temperature control element (7) is used, the planar contact elements (8a, 8b) of which consist of a metal plate or a planar shaped part made of metal, in particular stainless steel, preferably of material number 1.4404, the material thickness of which is in relation to its planar extent or in relation to the AMENDED SHEET (ARTICLE 19) The extent and shape of the fluid-carrying cavity (10) is selected such that the outer shell (9) of the temperature control element (7) can be deformed by applying negative pressure to the fluid-carrying cavity (10) in a range of 100 mbar to 700 mbar, preferably 400 mbar to 600 mbar, or by applying positive pressure in a range of 0.5 bar to 10 bar, preferably 0.5 bar to 1.5 bar, and subsequently returns substantially to its original shape by elastic restoring force.

9. Method according to claim 8, wherein a temperature control element (7) is used, the planar contact elements (8a, 8b) of which have a material thickness of less than 1 mm, preferably less than or equal to 0.1 mm.

10. Method for detecting aging of rechargeable battery cells (1) which are combined in at least one stack and / or at least one row to form a module (2) or a battery, comprising the method steps according to at least one of claims 1 to 12, wherein the temperature control element (7) is placed between two modules (2) or between a module (2) and another wall of the battery instead of between two battery cells (1), and wherein in the method steps the battery cells (1) adjacent to the temperature control element (7) are replaced by at least one module (2) adjacent to the temperature control element (7).

11. Arrangement for carrying out the method according to at least one of claims 1 to 10, comprising a number of rechargeable battery cells (1) which are combined in at least one stack and / or at least one row to form a module (2) or a battery, comprising at least one temperature control element (7) which is inserted between two adjacent battery cells (1) in such a way that it bears directly or indirectly against the adjacent battery cells (1), wherein an outer shell (9) of the temperature control element (7) is formed essentially from two planar contact elements (8a, 8b) which are connected to each other directly or indirectly at their perimeter and enclose at least one fluid-carrying cavity (10) between them, and wherein at least one of the planar contact elements (8a, 8b) is flexibly or elastically deformable in such a way that it AMENDED SHEET (ARTICLE 19) a aging-related bulging of the adjacent battery cells (1) with a reduction in the volume of the fluid-carrying cavity (10), with a measuring device (21) for detecting volume changes of the fluid-carrying cavity (10), and with a data processing device (23) for evaluating the detected volume changes with regard to aging-related bulging of the battery cells (1).

12. Arrangement according to claim 11, wherein the fluid-carrying cavity (10) is filled with a gas at a predetermined pressure and has a pressure sensor (26) or a motion sensor as a measuring device for detecting volume changes of the fluid-carrying cavity (10).

13. Arrangement according to claim 11, wherein the fluid-carrying cavity (10) of the temperature control element (7) has at least one inlet (11a) and at least one outlet (11b) through which it is accessible from the outside via the outer shell (9), and wherein the fluid-carrying cavity (10) is connected to a liquid circuit (16) with a defined liquid volume by means of the inlet (11a) and the outlet (11b), and wherein the measuring device (21) is configured to detect volume changes of the fluid-carrying cavity (10) in order to monitor the liquid volume and to detect an increase or change in the liquid volume in the parts of the liquid circuit (16) that do not belong to the fluid-carrying cavity (10).

14. Arrangement according to claim 13, wherein the liquid circuit (16) comprises a compensating reservoir (20) and the measuring device (21) is configured to detect volume changes of the liquid volume by measuring the filling volume of the liquid fraction (24) present in the compensating reservoir (20) or by measuring a gas pressure in the compensating reservoir (20). AMENDED SHEET (ARTICLE 19) 38 15. Arrangement according to at least one of claims 11 to 14, wherein the planar contact elements (8a, 8b) of the temperature control element (7) consist of a metal plate or a planar molded part made of metal, in particular stainless steel, preferably of material number 1.4404, the material thickness of which is selected in relation to its planar extent or in relation to the extent and shape of the fluid-carrying cavity (10) such that the outer shell (9) of the temperature control element (7) can be deformed by applying negative pressure to the fluid-carrying cavity (10) in a range of 100 mbar to 700 mbar, preferably 400 mbar to 600 mbar, or positive pressure in a range of 0.5 bar to 10 bar, preferably 0.5 bar to 1.5 bar, and subsequently returns substantially to its original shape by elastic restoring force.

16. Arrangement according to claim 15, wherein the planar contact elements (8a, 8b) of the tempering body (7) have a material thickness of less than 1 mm, preferably less than or equal to 0.1 mm.

17. Arrangement according to at least one of claims 11 to 16, wherein the fluid-carrying cavity (10) is designed as a meandering channel.

18. Arrangement according to at least one of claims 11 to 17, wherein the fluid-carrying cavity (10) is equipped with flow-influencing elements for generating or enhancing turbulent flow behavior of a fluid flowing through the cavity (10). AMENDED SHEET (ARTICLE 19) 39 19. Arrangement according to claim 18, wherein the flow-influencing elements are formed in at least one of the planar contact elements (8a, 8b), in particular by embossing.

20. Arrangement according to at least one of claims 11 to 19, wherein the elastic restoring force which allows the outer shell (9) of the temperature control element (7) to substantially return to its original shape is inherent in the material and / or is generated by spring elements which are preferably arranged in the fluid-carrying cavity (10).

21. Arrangement according to at least one of claims 11 to 20, wherein the outer shell (9) of the temperature control element (7) is essentially formed from two thin-walled metal plates made of circuit boards, in particular stainless steel circuit boards, as planar contact elements (8a, 8b) which are connected to each other around the perimeter by welding, soldering or gluing and enclose the fluid-carrying cavity (10) between them.

22. Arrangement according to claim 21, wherein the thin-walled metal plates have an embossed structure for influencing the flow of a fluid flowing through the fluid-carrying cavity (10).

23. Arrangement according to one of claims 21 or 22, wherein contours such as channels or channel halves are formed into the thin-walled metal plates to form the fluid-carrying cavity (10), in particular by cold forming, preferably stamping.

24. Arrangement according to claim 23, wherein a number of knobs (13) and / or short beads are formed into the contours, in particular stamped, as flow-influencing elements, which in particular also prevent the fluid-carrying cavity (10) from collapsing. AMENDED SHEET (ARTICLE 19) 25. Arrangement according to at least one of claims 11 to 24, wherein a plurality of temperature control elements (7) is inserted between battery cells (1), preferably one temperature control element (7) is inserted between all battery cells (1) of a module (2) or the battery. AMENDED SHEET (ARTICLE 19)

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