Cover assembly

Abstract

The invention relates to a cover assembly (1) of a battery cell, the cover assembly comprising: a metal base plate (2); a first terminal (3) which is arranged in a through-opening (20) in the base plate (2); a sealing element (5) which secures and seals the first terminal (3) to the base plate (2), wherein the sealing element (5) is arranged in the through-opening (20) and is designed to seal a first connection region (6) between the first terminal (3) and the sealing element (5) and a second connection region (7) between the base plate (2) and the sealing element (5) and to establish a connection between the first terminal (3) and the base plate (2), wherein the first connection region (6) has an untreated surface (11) on the first terminal (3), wherein the second connection region (7) has a treated surface (12) on the base plate (2), and wherein the sealing element (5) is designed to exert a compressive force F perpendicularly onto the untreated surface (11) of the first terminal (3) in order to seal the first connection region (6) in a fluid-tight manner.

Description

[0001] Cover assembly

[0002] Description

[0003] The present invention relates to a cover assembly and a battery cell with such a cover assembly.

[0004] Battery cells, such as prismatic cells, are used in rechargeable lithium-ion batteries, sodium-ion batteries, or supercapacitors, for example. The battery cell comprises a housing, which is usually made of aluminum, and a cover assembly that is attached to the housing and closes the housing. The cover assembly therefore has the task of closing and sealing the battery housing in order to protect the environment from the cell chemistry. The cover assembly should also prevent interfering substances such as oxygen or water from outside from entering the cell interior. Furthermore, the cover assembly should enable the connection of electrodes inside the battery cell and electrical contact outside the battery cell. For efficient cooling, it is advantageous if the battery cell is cooled by means of immersion cooling, in which the battery cell is completely placed in a liquid cooling medium.However, this places high demands on the sealing elements that seal a terminal (pole) in the base plate. In particular, problems arise regarding material compatibility between the electrolyte located inside the battery cell and the external liquid cooling medium.

[0005] The object of the present invention is to provide an improved cover assembly that is simple and cost-effective to manufacture, particularly suitable for immersion cooling with a liquid cooling medium. Furthermore, the object of the present invention is to provide a battery cell with such a cover assembly.

[0006] This object is achieved by a cover assembly having the features of claim 1 and a battery cell having the features of claim 13.

[0007] The subclaims show preferred developments of the invention.

[0008] The cover assembly according to the invention with the features of claim 1 has the advantage that the cover assembly is simple and cost-effective and is particularly suitable for immersion cooling. A sealing element which fastens a terminal to the base plate and, when mounted, seals an inside of the battery cell from an outside is particularly suitable for different liquids inside, in particular electrolytes, and outside, in particular immersion liquids. In other words, the sealing element preferably has sufficient material resistance to both an electrolyte and an immersion liquid on an outside of the battery cell over the service life of the battery cell. This is achieved according to the invention in that the cover assembly has a metallic base plate and a first terminal which is arranged in a through-opening of the base plate.The sealing element is designed to fasten and seal the first terminal to the base plate. The sealing element is thus arranged in the through-opening and designed to seal a first connection region between the terminal and the sealing element and a second connection region between the base plate and the sealing element and to provide a connection between the first terminal and the base plate. The first connection region has an untreated surface on the first terminal. The second connection region has a treated surface on the base plate. The treated surface is produced by surface treatment processes, for example as a plasma-activated surface or a surface treated with a primer or a surface coated with an adhesion promoter or a mechanically treated surface, e.g. by roughening.The sealing element is configured to exert a compressive force F perpendicular to the untreated surface of the first terminal in order to seal the first connection area between the sealing element and the first terminal in a fluid-tight manner, i.e., to seal it against liquids and gases. The untreated surface and the treated surface lie opposite one another on the sealing element. The sealing element is firmly fixed to the treated surface, and the treated surface results in unevenness and / or increased roughness compared to the untreated surface, which generates the compressive force F perpendicular to the untreated surface at the first terminal.

[0009] Thus, according to the invention, only the base plate needs to be surface treated, and the first terminal can be used without surface treatment. This makes the construction of the cover assembly simpler and more cost-effective. The compressive force F generated when the cover assembly is assembled still provides sufficient sealing capability for the sealing element on the first terminal.

[0010] Preferably, the base plate has a completely treated surface at the second connection area to the sealing element. In other words, the sealing element is fixed to the base plate only at treated surfaces of the base plate. Further preferably, the first terminal has a completely untreated surface at the first connection area. In other words, the first terminal has a surface at the first connection area, which faces the sealing element, that is free of unevenness and roughening, coatings, or the like. The surface at the first terminal is preferably a smooth metallic surface.

[0011] The sealing element is particularly preferably an elastomer. The use of an elastomer as a sealing element has the advantage that particularly high compressive forces can be easily generated toward the first connection area at the first terminal. Furthermore, elastomers have the advantage that they can be easily molded onto the base plate.

[0012] Further preferably, the first terminal is designed as a cathode, and the sealing element is made of an electrically conductive material. This provides corrosion protection for the cathode, since an electrical connection is formed between the cathode and the metallic base plate via the sealing element.

[0013] Further preferably, the sealing element undergoes a volume-enlarging treatment after assembly on the base plate and assembly of the first terminal. This volume increase of the sealing element can increase the compressive force F on the first terminal. The volume increase can be achieved, for example, by targeted swelling of the sealing element. Thus, the sealing element is preferably made of a swellable material and, after assembly, is subjected to a swelling process to increase the compressive force F of the sealing element on the first terminal. This significantly improves the sealing quality at the first connection area in a particularly cost-effective manner.

[0014] The cover assembly can further preferably be used for an immersion-cooled battery cell. The sealing element comes into contact on an inner side with an electrolyte of the battery cell and on an outer side with an immersion liquid that is used to cool the battery cell. The sealing element is preferably a one-piece component with a first partial area made of a first component and a second partial area made of a second component. The two components are made of two different materials. The first partial area is only exposed to the inside of the cover assembly and the second partial area is only exposed to the outside of the cover assembly. The first partial area therefore only comes into contact with the electrolyte on the inside of the cover assembly. The second partial area comes into contact exclusively with an immersion liquid, e.g.a heat transfer oil or the like, on the outside of the cover assembly. This makes it possible to provide a cover assembly suitable for immersion cooling in a simple and cost-effective manner.

[0015] Preferably, a dividing line is arranged between the first and second partial regions of the sealing element such that the dividing line lies in the through-opening of the base plate. The through-opening is preferably cylindrical, so that the dividing line abuts a cylindrical wall region of the through-opening.

[0016] Particularly preferably, the first component of the first subregion is selected such that the first component is resistant to an electrolyte of the battery cell. The second component is preferably selected such that the second component is resistant to a heat transfer fluid.

[0017] More preferably, the first component is made of a first elastomer, and the second component is made of a second elastomer that is different from the first elastomer. The first component is preferably EPDM (ethylene propylene diene rubber), and the second component is preferably NBR (acrylonitrile butadiene rubber).

[0018] Further preferably, a single adhesion-promoting coating is arranged on the base plate on a surface facing the sealing element. The adhesion-promoting coating improves the seal between the sealing element and the base plate. A single adhesion-promoting coating is sufficient, providing both improved adhesion of the first component of the first subregion and improved adhesion of the second component of the second subregion. The adhesion-promoting coating is preferably provided entirely within the through-opening and on an outer and inner side of the base plate.

[0019] Further preferably, the first terminal is designed as a cathode, and the first component and / or the second component exhibits electrical conductivity. This can prevent corrosion at the first terminal.

[0020] Further preferably, the first component and the second component are attached to the metallic base plate and the first terminal by means of an injection molding process. The two different components can be molded in one tool by two consecutive injection molding processes. Alternatively, two injection molding tools can be used.

[0021] More preferably, the cover assembly comprises a first and a second terminal. The sealing element at the first terminal is made of an electrically conductive material. The sealing element at the second terminal, which forms the anode, is made of an electrically non-conductive material.

[0022] The first and / or second terminal is preferably rectangular and, in particular, has a peripheral edge. The peripheral edge is preferably directed toward the inside of the battery cell.

[0023] The first terminal, which serves as the cathode, is preferably made of aluminum. The second terminal, which serves as the anode, is preferably made of an aluminum-copper composite. The base plate is more preferably made of aluminum.

[0024] More preferably, the sealing element comprises an outer region, a central region arranged in the through-opening, and an inner region. The outer region and the inner region are formed substantially parallel to the base plate and extend such that the outer region and the inner region enclose at least a portion of the base plate. The inner region is thus made from the first component, and the outer region is made from the second component.

[0025] Furthermore, the present invention relates to a battery cell comprising a cover assembly according to the invention.

[0026] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0027] Fig. 1 is a schematic sectional view of a cover assembly according to a first embodiment of the invention,

[0028] Fig. 2 is a schematic, enlarged partial sectional view of a first terminal of the cover assembly of Fig. 1,

[0029] Fig. 3 is an enlarged partial sectional view of the second terminal of the cover assembly of Fig. 1,

[0030] Fig. 4 is a schematic representation of a battery cell with a cover assembly according to the invention from Fig. 1, and

[0031] Fig. 5 is a schematic representation of a battery cell with a cover assembly according to a second embodiment of the invention.

[0032] A cover assembly 1 according to a first preferred embodiment of the invention will be described in detail below with reference to Figs. 1 to 4. As shown in Fig. 1, the cover assembly 1 comprises a metallic base plate 2. Two through-openings 20 are formed in the metallic base plate 2.

[0033] The cover assembly 1 further comprises a first terminal (cathode) 3 and a second terminal (anode) 4. One terminal each is arranged in one of the through openings 20 in the base plate 2.

[0034] The first terminal 3, which forms the cathode, is made entirely of aluminum. The second terminal 4, which forms the anode, is made of a first part 4a made of aluminum and a second part 4b made of copper.

[0035] The first and second terminals have the same geometric structure and are rectangular in shape (see Fig. 4).

[0036] The cover assembly 1 further comprises a first sealing element 5, which fixes the first terminal 3 to the base plate 2. The first sealing element 5 is made of an electrically conductive material. The first sealing element 5 comprises an outer region 50, a central region 51, and an inner region 52. The outer region 50 is directed toward the outside of the cover assembly. The inner region 52 is arranged on an inner side of the cover assembly 1.

[0037] As can be seen from Fig. 1 and 2, the sealing element is designed in a C-shaped section by two legs which are formed by the outer region 50 and the inner region 52, and the central region 51 connecting the outer region 50 and the inner region 52.

[0038] The first terminal 3, as further shown in Fig. 1, has a main area and a peripheral edge area 30, which is arranged on the inside of the cover assembly 1 and runs completely around the main area of ​​the first terminal 3. The corners of the first terminal, which is square, are rounded. This ensures a secure connection between the sealing element 5 and the first terminal 3.

[0039] The first sealing element 5 can be molded onto the first terminal 3 and the base plate 2 by an injection molding process, which can be inserted into an injection mold, for example, as inserts. Similarly, a second sealing element 5' is molded onto the second terminal 4 and the base plate 2.

[0040] The sealing elements 5, 5' on the first terminal 3 and the second terminal 4 are each geometrically identical. The sealing elements 5, 5' are arranged in the through-openings 20 and are configured to seal a first connection area 6 between the terminal and the sealing element and a second connection area 7 between the base plate and the sealing element, providing a connection between the terminals and the base plate as well as a secure fixation.

[0041] The sealing element 5 on the first terminal 3 is electrically conductive and comprises a first partial region 5a and a second partial region 5b. The sealing element 5 is a one-piece component. The first partial region 5a is made from a first component, and the second partial region 5b is made from a second component, with the two components being made of different materials. The first partial region 5a is directed exclusively toward the inside of the cover assembly and is exposed to the inside, while the second partial region 5b is directed exclusively toward the outside of the cover assembly and is exposed to the outside.

[0042] In other words, the first partial region 5a only comes into contact with an electrolyte 14 on an inner side of the cover assembly and the second partial region 5b only comes into contact with an immersion cooling fluid 15 on an outer side of the cover assembly.

[0043] A dividing line 13 between the first partial region 5a and the second partial region 5b is arranged in the region of the through-opening 20. The dividing line 13 is preferably parallel to the base plate 2. Particularly preferably, the dividing line 13 is arranged in the center of the through-opening 20 in the through-opening direction.

[0044] Since the first sealing element 5 is made of an electrically conductive material, corrosion protection can be achieved for the first terminal 3, which is designed as a cathode. It is sufficient if the first partial region 5a or the second partial region 5b is electrically conductive. An electrical connection is thus provided from the first terminal 3 to the base plate 2 via the electrically conductive first sealing element 5.

[0045] The provision of the dividing line 13 in the through-opening 20 ensures that the first partial region 5a comes into contact exclusively with the electrolyte and the second partial region 5b comes into contact exclusively with the immersion cooling fluid 15. The material of the first partial region 5a is selected such that it is resistant to the electrolyte 14. The material of the second partial region 5b is selected such that it is resistant to the immersion cooling fluid 15.

[0046] Elastomers are preferably provided as the material for the first and second partial areas 5a, 5b. The material for the first partial area 5a is preferably EPDM, and the material for the second partial area 5b is preferably NBR. At the first connection area 6, the first terminal 3 has an untreated surface 11. As can be seen in particular from Fig. 2, the sealing element 5 rests completely against the untreated surface 11 of the first terminal 3.

[0047] A treated surface 12 is formed on the base plate at the second connecting area 7. The connecting element 5 rests completely against the treated surface 12.

[0048] In other words, the sealing element 5 on the first terminal 3 lies completely against an untreated surface and the sealing element 5 on the base plate 2 lies completely against a treated surface 12.

[0049] Through these measures, the sealing element 5 is configured to exert a compressive force F perpendicularly on the untreated surface 11 of the first terminal 3. As a result, the sealing element 5 is pressed against the untreated surface 11 of the first terminal 3 with the compressive force F, so that the first connection area 6 is sealed fluid-tight.

[0050] A fluid-tight connection is established between the sealing element 5 and the base plate 2 on the treated surface 12 of the base plate 2. The treated surface 12 at the second connection region 7 can be treated using various chemical and / or mechanical processes or can have a coating. The coating is preferably an adhesion-promoting coating or a primer. Mechanical surface treatments include, for example, roughening and chemical surface treatments, such as an etching process. Various combinations of surface treatment measures are possible, which in particular increase the roughness of the treated surface 12.

[0051] As can be seen particularly from Figs. 2 and 3, no surface treatment is provided at the first connection area 6, so that the sealing element 5 is completely in contact with the untreated surface 11 at the first terminal. At the second connection area 7, the contact surface between the sealing element 5 and the base plate 2 is completely formed by the treated surface 12, so that the sealing element 5 is always in contact with the treated surface 12.

[0052] The elastomer material is preferably selected such that, after assembly of the cover assembly, a treatment for increasing the volume of the sealing element can be carried out, whereby the compressive force F of the sealing element 5 on the first terminal 3 is increased.

[0053] The first connection area 6 and the second connection area 7 on the second terminal 4 are formed in the same way as on the first terminal 3. Thus, the first terminal 3 and the second terminal 4 can be easily inserted as untreated components, for example, into an injection mold. Surface treatment is only necessary on the base plate in the area of ​​the through-openings 20.

[0054] At the second terminal 4, the first sub-region 5'a and the second sub-region 5'b of the second sealing element 5' do not have to be made of an electrically conductive material, but are made of an electrically non-conductive material. The first sub-region 5'a is resistant to the electrolyte 14, and the second sub-region 5'b is resistant to the immersion cooling fluid 15.

[0055] The cover assembly can be manufactured through multiple injection molding processes, preferably in a single injection mold. The base plate 2, the first terminal 3, and the second terminal 4 are provided as inserts. Since four different materials are used for the four sub-regions of the first and second sealing elements 5, 5', four individual injection molding processes are necessary in the shared injection mold. If only one of the two sub-regions 5'a, 5'b of the first sealing element 5 is electrically conductive, the other of the two sub-regions can be selected from the same material as the anode on the second terminal 4. As a result, only three injection molding processes are necessary, since one of the sub-regions on the first and second terminals 3, 4 can be molded in one injection process.

[0056] The C-shaped design of the sealing elements 5, 5' results in a relatively long first connection area 6, which provides media tightness between the sealing element 5 and the first terminal 3. A relatively long second connection area 7 also results between the sealing element 5, 5' and the base plate 2.

[0057] In addition to sealing the terminals 3, 4 and the base plate 2, the sealing elements 5, 5' also serve as a fixing device for fixing the terminals 3, 4 in the through-openings 20 of the base plate 2. In particular, by designing the first and second terminals 3, 4 with the circumferential edge region 30, 40 and steps 22 on the base plate 2, which lie at least partially over the circumferential edge regions 30, 40, a positive, secure fixing of the terminals 3, 4 can be realized.

[0058] A filling opening 8 and a bursting area 9 are also provided in the base plate 2.

[0059] Furthermore, an insulation plate 10 is provided on the inside of the base plate 2, which can be clipped to the base plate 2 before or after the injection process of the sealing elements 5, 5'. The insulation plate 10 has a circumferential edge 10a in the area of ​​the through-openings 20, which ensures correct positioning during the injection process of the injected sealing elements 5, 5'.

[0060] As can be further seen from Fig. 1, the two sealing elements 5, 5' are designed such that the inner region 52 partially encompasses the edge region 30, 40 of the two terminals 3, 4. This achieves an even better fixation of the terminals 3, 4 to the base plate 2.

[0061] Fig. 4 shows an assembled battery cell 100 in which the cover assembly 1 is fixed to a prismatic battery housing 101. The battery housing 101 is preferably made of the same material as the metallic base plate 2, in particular aluminum. This allows a simple connection between the cover assembly 1 and the battery housing 101, for example, by welding.

[0062] Thus, a cover assembly 1 for battery cells with immersion cooling can be provided, wherein the sealing elements 5, 5' consist of two-component materials, each of which can be optimized for resistance to the electrolyte 14 and the immersion cooling fluid 15. This achieves improved material resistance to the electrolyte and the immersion cooling fluid. The sealing elements 5, 5' are preferably injection-molded in one mold, preferably in multiple molds.

[0063] Adhesion-promoting coatings 11, 12 on the components to which the sealing elements 5, 5' are applied improve the tightness of the connecting areas 6, 7. This is further enhanced by the arrangement of the dividing lines 13 in the area of ​​the through openings 20.

[0064] Fig. 5 shows an alternative embodiment of a battery cell 100, in which two cell covers 1a and 1b are provided, each arranged on opposite narrow sides of the battery cell 100 and covering the battery housing 101. The first terminal 3 is arranged on the first cell cover 1a, and the second terminal 4 is arranged on the second cell cover 1b. The second cell cover 1b additionally has the filling opening 8. The bursting area 9 is provided in the battery housing 101 on the long narrow side (see Fig. 5). The sealing elements in Fig. 5 are designed in the same way as in the first exemplary embodiment.

Claims

Claims 1. A cover assembly (1) of a battery cell comprising: a metallic base plate (2), a first terminal (3) arranged in a through-opening (20) of the base plate (2), a sealing element (5) which fastens and seals the first terminal (3) to the base plate (2), wherein the sealing element (5) is arranged in the through-opening (20) and is configured to seal a first connection region (6) between the first terminal (3) and the sealing element (5) and a second connection region (7) between the base plate (2) and the sealing element (5) and to provide a connection between the first terminal (3) and the base plate (2), wherein the first connection region (6) on the first terminal (3) has an untreated surface (11), wherein the second connection region (7) on the base plate (2) has a treated surface (12), and wherein the sealing element (5) is configured,to exert a compressive force F perpendicular to the untreated surface (11) of the first terminal (3) in order to seal the first connection area (6) fluid-tight., 2. Lid assembly according to claim 1, wherein the base plate (2) has a fully treated surface (12) at the second connecting region (7) to which the sealing element (5) is fixed.

3. Cover assembly according to one of the preceding claims, wherein the first terminal (3) has a completely untreated surface (11) at the first connection region (6) against which the sealing element (5) seals.

4. Lid assembly according to one of the preceding claims, wherein the sealing element (5) is an elastomer.

5. Cover assembly according to one of the preceding claims, wherein the first terminal (3) is designed as a cathode and the sealing element (5) on the first terminal is made of an electrically conductive material.

6. Cover assembly according to one of the preceding claims, wherein the sealing element (5) undergoes a volume-enlarging treatment after assembly in order to increase the compressive force F on the first terminal (3).

7. Lid assembly according to one of the preceding claims, wherein the sealing element (5) is a one-piece component with a first partial region (5a) made of a first material and a second partial region (5b) made of a second material, wherein the first material is different from the second material, and wherein the first partial region (5a) is exposed exclusively to the inside of the lid assembly and the second partial region (5b) is exposed exclusively to the outside of the lid assembly.

8. Cover assembly (1) according to claim 7, wherein a dividing line (13) between the first partial region (5a) and the second partial region (5b) lies in the through opening (20).

9. Cover assembly (1) according to one of claims 7 or 8, wherein the first material of the first partial region (5a) is resistant to an electrolyte (14) and the second material of the second partial region (5b) is resistant to a heat transfer fluid (15).

10. Cover assembly (1) according to one of claims 7 to 9, wherein the first partial region (5a) is made of a first elastomer and the second partial region (5b) is made of a second elastomer which is different from the first elastomer.

11. Cover assembly (1) according to one of the preceding claims, which comprises the first terminal (3) and a second terminal (4), wherein a second sealing element (5') made of an electrically non-conductive material is arranged on the second terminal (4).

12. Cover assembly (1) according to claim 11, wherein the first terminal (3) and the second terminal (4) are each rectangular and in particular have a circumferential edge region (30, 40).

13. Battery cell comprising a cover assembly (1) according to one of the preceding claims.

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