Battery with immersion cooling

Abstract

A battery (1) comprising several electrochemical cells (2) is temperature-controlled by immersion cooling. The battery (1) comprises - a battery housing (3) with a prismatic basic shape, wherein the individual electrochemical cells (2) are also each prismatically shaped, - flat distributors (4, 5, 6, 7) for supplying and discharging immersion fluid on opposite sides of the battery housing (3), - meandering flow channels (12) which are formed between electrochemical cells (2) and which connect the flat distributors (4, 5, 6, 7) to one another and into which rigid spacing and flow-guiding elements (15) are inserted, wherein component groups which are formed from a plurality of cells (2) and spacing and flow-guiding elements (15) which are mechanically connected in series are each loaded by the force of a prestressing element (16).

Description

[0001] The invention relates to a battery comprising several electrochemical cells, in particular a secondary battery, with immersion cooling, i.e. immersion cooling.

[0002] Immersion cooling refers to a cooling process in which an object or assembly to be cooled, such as a battery cell and / or an electronic component, is directly surrounded by an electrically non-conductive dielectric fluid, i.e., immersed in the fluid. Depending on the requirements, the circulating immersion fluid can also be used to heat the object or assembly.

[0003] A battery that is temperature-controlled by immersion cooling is known, for example, from US Pat. No. 11,626,636 B2. One assembly of the known battery includes a compressible spacer assembly, i.e., a spacer arrangement. The battery according to US Pat. No. 11,626,636 B2 is designed for use in electric vehicles. This assembly is enclosed by an outer shell assembly. The use of a non-flammable dielectric as the immersion fluid is recommended.

[0004] Another temperature control device for individual battery cells assembled into a module is disclosed in US 11,677,107 B2. In this case, the battery cells have a cylindrical shape. The device according to US 11,677,107 B2 comprises sealing elements formed as two identical molded parts that are aligned point-symmetrically to each other.

[0005] DE 10 2020 120 746 A1 relates to a module for a high-voltage storage system with immersion cooling. The module comprises several battery cells arranged in a common housing and can, for example, be prismatically shaped or designed as pouch cells. Reversibly deformable spacer elements are arranged between the side surfaces of the battery cells. A coolant, whose thermal conductivity is specified as 0.1 W / m·K to 15 W / m·K, comes into direct contact with these side surfaces.

[0006] DE 10 2021 210 265 A1 describes a fluid management module for cooling an electrical energy storage device using immersion cooling. A valve unit is arranged between an inlet and an outlet port of the fluid management module, ensuring that fluid flows exclusively in the intended direction through a fluid path. Several cooling paths are routed through a housing of the fluid management module.

[0007] The invention is based on the object of providing a battery operating with immersion cooling that is further developed compared to the cited prior art and is characterized by a compact, production-friendly design while simultaneously achieving high achievable cooling performance. Furthermore, an advanced immersion cooling method is to be provided.

[0008] This object is achieved according to the invention by a battery, in particular a secondary battery, having the features of claim 1. The object is also achieved by a method designed according to claim 10 for cooling a battery comprising several electrochemical cells. Where reference is made to "cooling" in this text, the corresponding statements also apply to heating, i.e., generally, to temperature control. The explanations related to the cooling or heating method also apply mutatis mutandis to the device, i.e., the battery, in particular in the form of a secondary battery, and vice versa.

[0009] The battery according to the application, which has a plurality of electrochemical cells and provides for temperature control of the individual cells by immersion cooling, comprises - a battery housing with a prismatic basic shape, whereby the individual electrochemical cells are also each prismatically shaped, - several flat distributors for the supply and discharge of immersion fluid on opposite sides of the battery housing, - meandering flow channels formed between electrochemical cells, connecting the flat distributors to one another, into which rigid or elastic spacing and flow guiding elements are inserted, wherein component groups formed from several mechanically connected cells and spacing and flow guiding elements are each loaded by the force of at least one prestressing element, in particular in the form of a metallic or non-metallic spring element.

[0010] The invention is based on the idea that immersion cooling is fundamentally a highly efficient cooling method. When cooling electrochemical cells, it must be considered that the cells are subject to dimensional changes over the lifespan of the battery constructed from them, particularly due to charging and discharging processes. To accommodate such geometric changes in the cells, older approaches offer flexible spacers that also serve a flow-guiding function.

[0011] The solution according to the application deliberately departs from such approaches by separating the flow-guiding function performed by the spacer and flow-guiding elements from the geometric balancing function performed by the at least one spring element positioned in a row with the consecutively arranged cells. This enables permanent, flat contact of the spacer and flow-guiding elements with the cells over the entire service life of the battery. Alternatively, embodiments are possible in which the spacer and flow-guiding elements are elastic and identical to the preload elements. Another variant envisages combining elastic spacer elements with inherently rigid flow-guiding components.

[0012] The spacer and flow-guiding elements, which are not elastically flexible to a technically relevant extent and are generally also referred to as intermediate elements, are located in various embodiments on the largest surfaces of the cuboid-shaped cells of the battery. Of the respective surfaces, which have a square or other rectangular shape, for example, the spacer and flow-guiding element covers a partial area corresponding, for example, to less than half, in particular less than a quarter, of the aforementioned cell surface.

[0013] In this way, the cells, geometrically arranged in a row, are almost completely immersed in immersion fluid. This applies regardless of the electrical connection of the cells, i.e., the conventional parallel connections and / or series connections. The flow of the fluid, i.e., the flow of electrically non-conductive immersion fluid, is guided close to the cell walls, which can result in high flow velocities and highly pronounced turbulence. This promotes high heat dissipation and at least approximately uniform operating conditions for the cells throughout the battery housing.

[0014] The areas surrounded by the immersion fluid are not necessarily separated from other areas within the battery housing by seals. Even without such hermetic seals, flow-guiding structures can be formed within the battery housing or directly through the battery housing, in addition to the spacer and flow-guiding elements, which are inserted as rigid spacers between the individual electrochemical cells. These structures ensure a targeted distribution of the fluid flow.

[0015] For example, such flow-guiding structures are present as a perforated plate in at least one distributor for supplying or discharging immersion fluid to or from the cells. The individual openings in the perforated plate can have a cell-specific diameter. Furthermore, it is possible to separate the flow spaces on the cell side of the perforated plate from cell to cell by bringing the intermediate elements, i.e., spacer and flow-guiding elements, up to the perforated plate. This prevents any pressure differences that may exist between subvolumes bordering different cells from leading to undesirable compensating flows, which would result in uneven cooling of the cells.

[0016] The complete flow paths, fluidically connected in parallel, through which the immersion fluid can flow through the battery, can be designed such that all paths are at least approximately the same length. Embodiments can also be realized in which different flow paths have different lengths. This is possible, for example, when components in the battery housing, including the electrochemical cells arranged in a matrix, differ from one another in terms of their heat generation.

[0017] The battery housing either encloses a single interior space containing all electrochemical cells, or is modularly divided into several subspaces, each for a plurality of cells arranged in a matrix. Conversely, the battery housing, including its internal components and the cells, can represent only one module of a larger assembly of an electrochemical system, particularly a battery system. This allows for various design options for a "cell-to-pack" design. Various components of a hierarchically structured control system can be located inside or outside the battery housing.

[0018] Regardless of the number and arrangement of components inside and / or outside the battery housing that are intended to operate the battery system, in addition to the cells, each spring element that holds a row of cells under mechanical preload has the task of compensating for tolerances in exactly one dimension. In a direction orthogonal to this, the battery cells can also be arranged in rows, with the cells lined up with their narrow sides in this direction. With regard to the flow of the immersion fluid, the narrow sides of the cells are of secondary importance.Between the narrow sides, i.e. the small side surfaces of the cells, a gap may exist which forms a flow channel which is parallel to the channels formed by the spacer and flow guide elements and also contributes to the heat exchange, whereby due to the fact that the narrow sides are small compared to the surfaces against which the spacer and flow guide elements rest, a specially shaped flow channel on the small side surfaces can be dispensed with.

[0019] In a modified version, flow-guiding elements are also used on the small side surfaces of the cells. It is also possible to completely or partially close the gaps on the small side surfaces with spacers, which can increase mechanical load capacity and optimize cell attachment.

[0020] Overall, the design according to the application achieves both a stable attachment of the cells in the battery housing and a constant geometry of the flow chambers, which is relevant for immersion cooling. At the same time, the spring element, which preloads a complete row of cells as well as the spacer and flow guide elements inserted between the cells, occupies only a small installation space in relation to the cells and the entire volume in which the spacer and flow guide elements are located.

[0021] The housing of the battery has, in particular, a cuboid-like, non-cubic basic shape, with first-order distributors being arranged on opposite narrow sides and second-order distributors, which are connected to the first-order distributors, being arranged on the top and bottom of the battery housing, and with the electrochemical cells being placed in matrix form between the top and bottom of the battery housing.

[0022] Optionally, at least one pressure relief device, which can be designed as a rupture disc or a pressure relief valve, is located in the upper area of ​​the battery housing. Furthermore, vent valves can be installed, particularly at the corners of the battery housing.

[0023] The spring element, i.e., the preload element, which applies a preload force to a row of battery cells, is designed, for example, as a leaf spring, a disc spring, or an arrangement of several springs. Adjustment options can be provided by a separate, inherently rigid element, for example, in the form of a disc, against which the spring element rests.

[0024] Instead of a spring-type preload element, a flat element, such as an intermediate layer made of an elastic, optionally foamed material, can also be used to mechanically preload the battery cells. Regardless of the material and geometry of the elements against which the cells rest when exerting a compressive force, screws can be provided to adjust the preload.

[0025] One possible design of a preloading device consisting of several preloading elements provides for individually adjustable plate elements to load a row of electrochemical cells. The plate elements can be adjustable using screws.

[0026] At one point in the immersion fluid circuit, for example, between the battery housing and a pump provided for conveying the dielectric immersion fluid, a filling device can be arranged, which includes a compensation tank for the immersion fluid. Venting devices, apart from the filling device, can be arranged, in particular, at the corners of the cuboid-shaped or otherwise prismatic battery housing.

[0027] To raise the battery cells to a higher temperature level when needed, a heating device can be integrated into the immersion fluid circuit. Such a heating device is powered, for example, electrically or by waste heat from another device, in particular an internal combustion engine.

[0028] Any number of electrical, electronic, or electromechanical components, for example at least one sensor, in particular a temperature sensor and / or a voltage sensor, can be integrated into the immersion fluid circuit. Such components can generally be arranged inside or outside the battery housing.

[0029] The method according to the application for cooling a battery comprising several electrochemical cells provides for an immersion fluid to be passed through meandering channels that are at least partially connected in parallel in terms of flow. These channels are formed between the electrochemical cells and are kept open by means of spacer and flow guide elements. Spacer and flow guide elements, which are placed in several channels that are connected in parallel in terms of flow, are held under mechanical tension by the force of a spring element.

[0030] The battery according to the application, which can be temperature-controlled by the method according to claim 10, is particularly suitable for regular rapid charging due to the optimized heat transfer between the cells and the immersion fluid, especially when the battery is designed as a traction battery for a vehicle. Use of the battery in a stationary system is also conceivable.

[0031] Several embodiments of the invention are explained in more detail below with reference to a drawing. In the drawings: Fig. 1 a perspective view of a battery tempered by immersion cooling, Fig. 2 a largely corresponding to the battery according to Fig. 1 assembled battery in exploded view, Fig. 3 the battery after Fig. 1 in plan view, Fig. 4 and Fig. 5 the battery according to the Fig. 1 and Fig. 3 in sectional views, Fig. 6 a side surface of the battery Fig. 1 including structures for supplying immersion fluid, Fig. 7 in a side view a compared to the design according to Fig. 1 modified way of supplying immersion fluid to cells of a battery, Fig. 8 in a representation analogous Fig. 6 a side surface of the battery Fig. 1 including structures for the recirculation of immersion fluid, Fig. 9 the bottom of the battery Fig. 1, Fig. 10 components inside the battery casing Fig. 1 in plan view, Fig. 11 and Fig. 12 sectional views of the arrangement according to Fig. 10, Fig. 13 a detail from Fig. 12 including a spring element, Fig. 14 an alternative design of a spring element of a battery in a representation analogous Fig. 13, Fig. 15 a spacing and flow guiding element of a battery, Fig. 16 a detail of a battery including several spacing and flow guiding elements in plan view, Fig. 17 a tensioning frame of a battery in perspective view, Fig. 18 section of the clamping frame and the battery components located therein, Fig. 19 a section of a battery with an elastic intermediate layer for mechanical prestressing of battery cells, Fig. 20 the arrangement according to Fig. 19 in plan view, Fig. 21 in a side view, a section of a battery with separately adjustable plate elements, which are intended to apply a preload force to a row of battery cells, Fig. 22 shows a sectioned view of a detail of the arrangement according to Fig. 21, Fig. 23 a battery system intended for use in a vehicle including the battery according to Fig. 1.

[0032] Unless otherwise stated, the following explanations refer to all exemplary embodiments. Corresponding or essentially equivalent parts are identified by the same reference numerals in all figures.

[0033] A battery system, designated overall by reference numeral 10, comprises a rechargeable battery 1 whose battery housing 3 has a cuboidal basic shape. A plurality of electrochemical cells 2, i.e., battery cells, are temperature-controlled by immersion cooling. A dielectric fluid is used as the immersion fluid. To supply the immersion fluid to the battery cells 2, an inlet distributor 4, referred to as a first-order planar distributor, is located on a first narrow side of the battery housing 3. On the side of the battery housing 3 opposite the distributor 4, there is a collector 5, which generally also represents a first-order planar distributor. From the inlet distributor 4, the immersion fluid is passed on to a second-order planar distributor 6, which is located on the top side of the battery housing 3.In an analogous manner, a flat second-order distributor 7, which is located on the underside of the battery housing 3, is connected to the collector 5. The terms "top" and "bottom" refer to the positions shown in the . Fig. 1 and Fig. 2 and do not imply any statement about the actual orientation of the battery 1 in space.

[0034] Within the flat second-order distributor 6, several mutually parallel upper inlet transverse channels 8 are formed, which taper in the flow direction of the immersion fluid, i.e., with increasing distance from the inlet distributor 4. Each upper inlet channel 8 is assigned to a row 23 of battery cells 2. Channel sections 9 extend from the upper inlet transverse channel 8, which guide the immersion fluid between the individual battery cells 2 of a row 23. In general, flow channels, regardless of their location in the immersion fluid circuit, designated overall by 20, are designated by 11. Meander-shaped flow channels 12 are assigned to the flow channels 11, the meandering shape of which is predetermined by spacing and flow-guiding elements 15, which will be discussed in more detail below. Mounting contours 13 can be seen on the outer sides of the battery housing 3.Connection or connecting elements 14, for which the term busbar is sometimes used, are arranged partly inside and partly outside the battery housing 3.

[0035] In the embodiment according to Fig. 1 the immersion fluid flows out, as well as from Fig. 6, in the inlet manifold 4 from bottom to top. An alternative embodiment in which the immersion fluid flows in the inlet manifold 4 from top to bottom is shown in Fig. 7 illustrates.

[0036] Regarding the recirculation of the immersion fluid in collector 5, there are also various design options. Fig. 8 shows the design after Fig. 1, in which the immersion fluid flows from bottom to top in the collector 5. In an alternative embodiment not shown, a flow in the collector 5 from top to bottom is also possible. Such a configuration would be possible with the variant of the inlet distributor 4 according to Fig. 7 compatible.

[0037] If the immersion fluid flows from the upper inlet transverse channels 8 between the battery cells 2, longitudinal webs 30 and transverse webs 31, which are provided by each spacing and flow guiding element 15 and abut the adjacent battery cells 2, ensure the meandering shape of the flow channels 12. Two meandering flow channels 12 of equal length are formed through each of the flat spacing and flow guiding elements 15.

[0038] The arrangement of a row 23 of battery cells 2 and associated spacing and flow guide elements 15, which are each inserted between two battery cells 2, is prestressed by a spring element 16, generally referred to as a tensioning element or prestressing element, which is located within the battery housing 3. Forces generated, among other things, by the spring element 16, i.e. tensioning element, are absorbed by tension elements 27, which are attributable to the battery housing 3. Tension screws, which are screwed into the tension elements 27, are designated 26. Both in the embodiment according to Fig. 13 as well as in the design according to Fig. 14, the clamping element 16 comprises several disc springs 17. In the variant according to Fig. 14 also features a compensating element 18 in the form of a disc. The compensating element 18 enables tolerance compensation through so-called shims and is therefore also referred to as a shim disc.

[0039] Further details can be found in the Fig. 10 and Fig. 11. The rows 23 of battery cells 2 are then electrically connected to one another by connecting elements 24. The supply and discharge of the immersion fluid takes place via inlet-side flow cross-sections 28 and outlet-side flow cross-sections 29, which are located above and below the cells 2, respectively. The flow cross-sections 28, 29 are fluidically connected to the first-order flat distributors 4, 5 via the second-order flat distributors 6, 7. Formed by the flat distributor 4, among other things, is a lateral inlet channel 19. Within the flat distributor 5, there is, among other things, a lateral return channel 25. The latter return channel 25 is connected to a return cross-channel 21 located in the flat distributor 7, as well as channel sections 22 that adjoin the lower return cross-channel 21 and are also located in the second-order flat distributor 7.

[0040] The Fig. 17 shows a clamping frame 53 which is assigned to the battery housing 3 and which is provided for receiving the rows 23 of battery cells 2. The clamping frame 53 comprises side parts 54, 55 and partition walls 56 and is particularly suitable for use in a battery 1 according to Fig. 18, in which, among other things, several pre-tensioning elements 15 can be seen. In contrast to the variant according to Fig. 15 are the prestressing elements 15 according to Fig. 18 elastic, so that there is no need for separate elastic elements in this case.

[0041] Another possibility to apply a preload force to a row 23 of battery cells 2 is shown in the Fig. 19 and Fig. 20. Here, the function of the prestressing elements 16 is taken over by elastic intermediate layers 57, which are located within the clamping frame 53.

[0042] In the example according to the Fig. 21 and Fig. 22 comprises several adjacent plate elements 58, each of which is assigned to a row 23 of battery cells 2. Adjusting screws 59 allow the plate elements 58 to be individually adjusted, thus varying the compressive force acting on the corresponding row 23 of battery cells 2. Screws 60 are screwed into the intermediate walls 56 of the clamping frame 53.

[0043] The Fig. Figure 23 shows the connection of the immersion fluid circuit 20 to a cooling water circuit 32 in a motor vehicle. The cooling water circuit 32 comprises a cooler 33, a fan 34, a pump 35, and a control module 36, which is linked to other vehicle components. A valve within the cooling water circuit 32 is designated 37. A heat exchanger 38 represents both a component of the cooling water circuit 32 and a component of the immersion fluid circuit 20.

[0044] Instead of the cooling water circuit 32, a refrigerant circuit can also be used to transfer heat between the circuit in question and the immersion fluid. In the case of a refrigerant circuit, the pump 35 is replaced by a refrigerant compressor and the valve 37 by an expansion valve.

[0045] Within the immersion fluid circuit 20, immersion fluid lines are generally designated 52. The immersion fluid lines 52 are hermetically separated from the cooling water lines designated 51. A variable distribution of the immersion fluid flow between the heat exchanger 38 and a heating device 40 is possible by means of a control valve 39.

[0046] Immersion fluid is refilled as needed via a filling device designated overall by 44. The filling device 44 comprises a filling module 45 inserted into the immersion fluid circuit 20 and a compensation tank 46 containing a membrane 47. 48 denotes a valve associated with the filling device 44.

[0047] The immersion fluid circuit 20 further comprises a pump 49 and a filter 50. As further shown in Fig. As can be seen from Figure 23, there are vent valves 41 located at corners in the upper area of ​​the battery housing 3. A sensor 43 detects conditions within the battery housing 3. A safety valve 42 is positioned such that, in the event of an inadmissible pressure load, the smallest possible amount of immersion fluid escapes from the housing 3, thus maintaining the possibility of cooling the battery 1 as far as possible. List of reference symbols 1 battery 2 electrochemical cell, battery cell 3 battery housing 4 flat first-order distributor on a first narrow side of the battery housing, inlet distributor 5 flat first-order distributor on a second narrow side of the battery housing, collector 6 flat second-order distributor on the top of the battery case 7 flat second-order distributor on the underside of the battery housing 8 upper inlet cross channel 9 Canal section, connecting to the upper inlet cross canal 10 Battery system 11 Flow channel, general 12 Flow channel, meandering 13 Mounting contour 14 Connection or connecting element, busbar 15 Distance and flow guide element 16 Spring element, preload element 17 Disc spring 18 Compensating element, disc 19 side inlet channel 20 Immersion fluid circuit 21 lower return cross channel 22 Channel section, connected to the lower return cross channel 23 rows of battery cells 24 connecting element 25 side return channel 26 clamping screw 27 Tension element 28 Flow cross-section, inlet side 29 Flow cross-section, outlet side 30 Longitudinal web 31 Crossbar 32 Cooling water circuit 33 coolers 34 fans 35 Pump in the cooling water circuit 36 Control module 37 Valve in the cooling water circuit 38 heat exchangers 39 Control valve 40 Heating device 41 Vent valve on the battery housing 42 Safety valve 43 Sensor 44 Filling device 45 filling module 46 Expansion tank 47 Membran 48 Valve in the filling device 49 Pump in the immersion fluid circuit 50 filters 51 Cooling water line 52 Immersion fluid line 53 clamping frames 54 side panel 55 side panel 56 Partition wall 57 elastic intermediate layer 58 movable plate element 59 Adjusting screw 60 screw QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This 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

[0000] US 11,626,636 B2

[0003] US 11,677,107 B2

[0004] DE 10 2020 120 746 A1

[0005] DE 10 2021 210 265 A1

[0006]

Claims

[1] Battery (1) made of electrochemical cells (2), wherein temperature control of the electrochemical cells (2) is provided by means of immersion cooling, comprising - a battery housing (3) with a prismatic basic shape, wherein the individual electrochemical cells (2) are also each prismatically shaped, - flat distributors (4, 5, 6, 7) for supplying and draining immersion fluid on opposite sides of the battery housing (3), - meandering flow channels (12) connecting the planar distributors (4, 5, 6, 7) formed between electrochemical cells (2), into which spacer and flow guide elements (15) are inserted, wherein component groups consisting of several mechanically connected cells (2) and spacer and flow guide elements (15) are each subjected to the force of at least one prestressing element (16). [2] Battery (1) according to claim 1, characterized by, that the battery housing (3) has a cuboid, not cube-shaped, basic form, wherein first-order distributors (4, 5) are arranged on opposite narrow sides and second-order distributors (6, 7) which are connected to the first-order distributors (4, 5) are arranged on the top and bottom of the battery housing (3), wherein the electrochemical cells (2) are placed in matrix form between the top and bottom of the battery housing (3). [3] Battery (1) according to claim 1 or 2, characterized by at least one pressure relief device (42), namely a burst disc or a pressure relief valve, in the upper part of the battery housing (3). [4] Battery (1) according to any one of claims 1 to 3, characterized by at least one mechanical compensating element (18) on which the prestressing element (16) is supported. [5] Battery (1) according to any one of claims 1 to 4, characterized bya filling device (44) arranged between the battery housing (3) and a pump (49) intended for conveying immersion fluid, to which a reservoir (46) for immersion fluid is to be added. [6] Battery (1) according to any one of claims 1 to 5, characterized by , that there are vent valves (41) in the corners of the battery housing (3). [7] Battery (1) according to any one of claims 1 to 6, characterized by , that prestressing elements (16) in the form of individually adjustable plate elements (58), each of which loads a row (23) of electrochemical cells (2), are present. [8] Battery (1) according to any one of claims 1 to 7, characterized by a heating device (40) integrated into the immersion fluid circuit (20). [9] Battery (1) according to any one of claims 1 to 8, characterized by, that at least one electrical component, including at least one sensor (43), is integrated into the immersion fluid circuit (20) within the battery housing (3). [10] Method for cooling a battery (1) comprising several electrochemical cells (2), wherein an immersion fluid is guided through meandering channels (12) which are at least partially connected in parallel in terms of flow technology and which are formed between the electrochemical cells (2) and are kept open by means of spacer and flow guide elements (15), wherein spacer and flow guide elements (15) which are placed in several channels (12) connected in parallel to each other are held under mechanical tension by the force of at least one preload element (16).

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