Modular device for thermal control of battery cells with central, coaxial conductor

Abstract

The invention relates to a device for temperature control of electrochemical cells, in particular cylindrical cells, with a coaxially constructed conduit running centrally inside the cell for conveying a liquid or gaseous temperature control medium. The outer tube of the conduit has an external thread that is electrically connected to a first pole of the cell, while the cell housing forms the second pole. The cell is screwed to a base plate via the thread, which has complementary fluidic and electrical connections. The screwing action simultaneously establishes the mechanical, electrical, and fluidic connections. An insulating layer is optionally provided between the conduit and the active cell components. The device enables space-saving, uniform temperature control and allows for the easy replacement of individual cells in modular battery systems.

Description

The invention relates to a device for temperature control of electrochemical energy storage units, in particular cylindrical cells, as used in battery systems for electric vehicles, stationary storage facilities, or comparable applications. The device enables the targeted temperature control of the cells as well as their electrical and mechanical integration into a modular battery system. 2 TECHNICAL BACKGROUND In modern electrochemical energy storage systems, particularly traction batteries for electric vehicles or stationary storage systems, a large number of individual battery cells are typically connected to form a composite system. The flawless functioning of each individual cell is essential for the performance and safety of the overall system. A key challenge is thermal management. It is known that temperature differences within or between cells can lead to uneven aging, efficiency losses, or, in extreme cases, safety risks. Therefore, cooling systems are used to maintain the cells within an optimal temperature range during operation. In many known systems, cooling is achieved via external structures such as cooling plates or pipes, which are mounted on or between the cell modules and often bonded or potted in place. These solutions have several disadvantages. Firstly, they are space-consuming and make it difficult to replace individual cells, as these are mechanically and thermally integrated into the cooling system. Secondly, cooling units arranged on only one side, in particular, often lead to asymmetrical heat dissipation, which can result in uneven temperature distribution across the cells. Several solutions aimed at improving thermal performance are known from the prior art. For example, EP 3 089 257 A1 describes a battery system with a duplex pipe to reduce the need for cooling space. US 10 193 196 B1 discloses a central heat pipe for heat dissipation from the cell interior. US 10 381 694 B2 shows a cooling system with integrated cooling channels in structural hollow bodies. DE 10 2022 106 656 A1 describes a battery cooling device with cooling channels integrated into the cell housing for direct heat dissipation. Furthermore, solutions are known in which temperature control or functional elements are arranged within the battery cell or interact with its structural design. For example, DE 10 2023 120 433 A1 describes battery cell arrangements with a coolant pipe structure located within the cell housing, which interacts with a cooling plate assembly for supplying and removing a coolant. DE 10 2021 121 017 A1 relates to a cylindrical battery cell with a central rod extending along the cell's longitudinal axis, passing through an end face, and serving to secure the cell in a battery module. DE 10 2023 128 944 A1 discloses hollow prismatic or cylindrical battery cells with a hollow central tube around which electrode and separator layers are arranged, as well as a heat exchange system with fluid channels for supplying the central tube with fluid.The CN 2 22 190 914 U relates to a tube-cooled cylindrical battery in which a cooling tube is passed through the center of a cylindrical cell and fluidically connected to the cell ends. The solutions mentioned demonstrate different approaches to temperature control and the structural integration of battery cells. However, limitations remain, particularly regarding modularity and the ability to easily replace individual cells within a cell assembly without affecting adjacent components. Furthermore, disadvantages persist concerning the required installation space and the need for a uniform temperature distribution. 3 The problem underlying the invention The invention is therefore based on the objective of providing a device for temperature control of electrochemical cells that enables effective and uniform temperature control without restricting the modularity of the overall system. In particular, the replacement of individual cells, even in densely packed cell assemblies, should be possible without damaging adjacent components or temperature control elements. 4 The solution according to the invention The problem is solved by a device for temperature control of electrochemical cells, in which a coaxially constructed conduit for conveying a temperature control medium runs centrally through the interior of the cell. The conduit is permanently integrated into the cell and serves to supply and remove a liquid or gaseous medium suitable for precise temperature control of the cell. The coaxial cable consists of an inner tube and an outer tube arranged concentrically around it. The outer tube has an external thread at its free end and is electrically connected to one pole of the cell. The second electrical pole is formed by the cell housing or the end face of the cell. The cell can be screwed to a multi-layered base plate via the aforementioned external thread on one side. The base plate has complementary connections for fluidic and electrical contact. Screwing the components together simultaneously establishes mechanical fixation, electrical connection between both poles, and coupling of the fluidic lines. An electrically insulating layer is provided between the coaxial cable and the electrical components inside the cell, provided a conductive temperature control medium is used. This insulating layer can be omitted if electrically non-conductive media are used. The design according to the invention allows for uniform and effective temperature control of the cell while requiring minimal installation space. Furthermore, the single-sided screw connection and modular construction significantly simplify the replacement of individual cells within a larger cell assembly. List of characters Fig. 1 shows a schematic overall view of an electrochemical cylindrical cell with a centrally integrated coaxial line for temperature control. Fig. 2 shows a first embodiment of the connection between a cell and a base plate, including mechanical, electrical, and fluidic contacts. Fig. 3 shows a second embodiment of the connection between the cell and the base plate with an alternative sealing design. Fig. 4 shows a first embodiment of the transition from the inner to the outer tube without insulation. Fig. 5 shows a first embodiment of a transition from the inner tube to the outer tube of the coaxial line with an insulating layer. Fig. 6 shows a second embodiment of the transition from the inner to the outer tube without insulation. Fig. 7 shows a second embodiment of the transition from the inner tube to the outer tube of the coaxial line with insulation. 5 Concrete examples of implementation Fig. 1 shows an electrochemical cell (1), for example a cylindrical cell, which has a cell winding (2) around a coaxially arranged winding mandrel (3). For temperature control of the cell, a liquid or gaseous medium is supplied via an inlet channel (4) and discharged via an outlet channel (5). The medium flows along a coaxially arranged channel consisting of an outer tube (6) and an inner tube (8), thus forming an annular channel (9). An electrically insulating layer (7) can be provided if the temperature control medium used is conductive. The outer tube (6) is equipped at its free end with an external thread (10) for screwing it to a base plate. During operation, the outer tube (6) acts as the first electrical pole, while the cell housing forms the second pole. 5.1 First embodiment (Fig. 2) Fig. 2 shows the mechanical, electrical, and fluidic connection of the cell (1) to a base plate. The external thread (10) of the outer tube (6) engages a complementary internal thread (11) of the base plate. Screwing in the tube creates an axial preload that simultaneously serves as a mechanical fix, a seal, and an electrical connection. A sealing element (12) prevents the temperature control medium from escaping. The contact surface (13) electrically connects the cell housing (pole 2); the contact surface (14) couples the external thread (pole 1). An insulating layer (15) in the base plate reliably separates both poles from each other and from the temperature control medium. 5.2 Second embodiment (Fig. 3) Fig. 3 shows an alternative base plate design in which the position of the seal (12) and insulating layer (15) is changed. The sealing element (12) can, for example, be positioned higher or lower in the base plate to accommodate different housing or connection geometries. Here, too, the connection is made via the external thread (10) on the outer tube (6); this simultaneously connects the cell (1) and the base plate fluidically and electrically. 5.3 Variants of the coaxial cable (Figs. 4 to 7) The outer tube (6) and inner tube (8) together form the annular channel (9) for the temperature control medium. In all versions, the inner tube (8) is mechanically fixed to the outer tube (6) or to the intermediate insulating layer (7) via radially extending connecting elements and guided centrally. Figures 4, 5, 6 to 7 differ in the geometry of the transition from the inner to the outer tube. While the designs according to Figures 4 and 5 are structurally simple, the variants according to Figures 6 and 7 allow for improved flow guidance in the transition area. Figure 4: Transition without insulating layer (7); suitable for non-conductive temperature control media. Figure 5: Transition with full-surface insulating layer (7) for electrical separation of the inner and outer tubes. Figure 6: Flow-optimized design according to Figure 4 with adapted transition geometry. Figure 7: Flow-optimized design according to Figure 5 with integrated insulating material. In all variants, the external thread (10) allows the cell (1) to be removed from the base plate from one side. This supports the modular design, and the coaxial cable ensures uniform and efficient temperature control of the cell. Reference symbol list 1 Electrochemical cell / cylindrical cell 2 Cell winding 3 Coaxially mounted winding mandrel 4 Inlet channel for temperature control medium 5 Outlet channel for temperature control medium 6 Outer tube of the coaxial line (electrically conductive) 7 Electrically insulating layer 8 Inner tube 9 Channel for guiding the temperature control medium 10 External thread of the outer tube 11 Internal thread of the base plate (complementary to 10) 12 Sealing element in the base plate 13 Contact surface for cell housing (pole 2) including busbar 14 Contact surface for external thread (pole 1) including busbar 15 Insulating layer inside the base plate

Claims

Device for temperature control of at least one electrochemical cell comprising (a) an electrochemical cell (1), which has a conduit running centrally inside the cell for guiding a temperature control medium, which is coaxially constructed from an inner tube (8) and an outer tube (6) extending concentrically around it, wherein the temperature control medium is guided within the conduit, wherein the outer tube (6) has an external thread (10) at its end extending out of the cell (1), wherein the external thread (10) is electrically connected to a first pole of the cell (1), and wherein a cell housing or an end face of the cell (1) serves as the second electrical pole, (b) a base plate, which forms a receptacle for the cell (1), and which is designed complementary to the coaxial conduit, wherein the base plate has fluidic connections to the inner tube (8) and to the outer tube (6) of the conduit.- wherein the base plate has electrical contact points for the external thread (10) as well as for the cell housing or the end face of the cell (1),- wherein the mechanical, electrical and fluidic connection is simultaneously established by screwing the cell (1) to the base plate,- and wherein the screwing takes place on an end face of the cell (1). Device according to claim 1, characterized in that an electrically insulating layer (7) is provided between the inner tube (8) and the outer tube (6). Device according to one of the preceding claims, characterized in that the base plate has a multi-layered structure with electrically conductive (13, 14) and electrically insulating layers (15) and that the cell-side receiving of the base plate comprises seals (12) which provide a fluidic seal of the connection to the coaxial line. Device according to one of the preceding claims, characterized in that the cell (1) is attached exclusively to the base plate and does not require any further fixing points. Device according to one of the preceding claims, characterized in that the temperature control medium is liquid or gaseous and serves for the active cooling or heating of the cell (1). Device according to one of claims 1 or 3 to 5, characterized in that when using an electrically non-conductive temperature control medium, an electrically insulating layer (7) can be dispensed with. Device according to one of the preceding claims, characterized in that the electrical contacting is effected by force-fit pressing of the end-face pole surface of the cell (1) onto a planar contact surface (13, 14) in the base plate. Device according to claim 7, characterized in that alternatively resilient or elastically prestressed contact surfaces (13, 14) are provided. Device according to one of the preceding claims, characterized in that by screwing the external thread (10) of the outer tube (6) into the base plate an axial preload is generated which effects both the fluidic sealing and the electrical contacting.

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