Cover assembly comprising a cap for battery cells

Abstract

The invention relates to a cover assembly of a battery cell, the cover assembly comprising: a metal base plate (2); at least one terminal (3, 4) which is arranged in a through-opening (20) in the base plate (2); a sealing element (5) which secures and seals the terminal to the base plate (2), wherein the sealing element (5) has an outer face, wherein the sealing element (5) is arranged in the through-opening (20) and is designed to seal a first connection region (6) between the terminal (3, 4) and the sealing element (5) and a second connection region (7) between the base plate (2) and the sealing region (5) and to establish a connection between the terminal (3, 4) and the base plate (2); and a cap (11, 11') which completely covers the sealing element (5) on the region thereof lying towards the outside.

Description

[0001] Cover assembly with cap for battery cells

[0002] Description

[0003] The present invention relates to a cover assembly with a cap for a battery cell, in particular a prismatic cell, and to 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, typically made of aluminum, and a cover assembly that is attached to the housing and seals the housing. The cover assembly thus serves to seal the battery housing in a media-tight manner in order to protect the environment from the cell chemistry. The cover assembly should also prevent interfering substances such as oxygen or water from penetrating the cell interior. Furthermore, the cover assembly should enable the connection of electrodes inside the battery cell and electrical contact outside the battery cell.

[0005] It is an object of the invention to provide an improved cover assembly and a battery cell with such a cover assembly with simple and cost-effective manufacture.

[0006] This object is achieved by a cover assembly having the features of claim 1 and a battery cell having the features of claim 15.

[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 a significantly improved seal is possible in the area of ​​the electrical poles, which extend through through openings in the cover assembly. The cover assembly according to the invention has a particularly simple and cost-effective design. A gap at the pole feedthrough can be reliably sealed in all operating situations, particularly at very cold and very hot temperatures, so that leakage via the gap at the pole feedthroughs can be prevented according to the invention. The provision of a cap enables particularly good protection, especially in areas adjacent to the pole feedthrough.

[0009] This is achieved according to the invention in that the cover assembly of a battery cell comprises a metallic base plate and at least one terminal (electrical pole) which is arranged in a through-opening of the base plate. The terminal is designed to enable electrical contact between an outer side of the battery cell and an inner side of the battery cell. Furthermore, the cover assembly comprises a sealing element which fastens and seals the terminal to the base plate. The sealing element thus has a dual function: on the one hand, to seal the terminal and on the other hand to fasten the terminal. The sealing element is arranged in the through-opening of the base plate and designed to seal a first leakage path between the terminal and the sealing element and a second leakage path between the base plate and the sealing element, and to provide a connection and fixation between the terminal and the base plate.The sealing element has an outer side, with a cap arranged on the outwardly facing areas of the sealing element. The cap completely covers all outwardly facing areas of the sealing element. This improves the sealing element's protection, ensuring complete protection against external influences throughout the service life of the cover assembly. This enables the sealing element to adequately seal a battery cell and thus fully meet the necessary safety requirements throughout the entire service life of the cover assembly.

[0010] Particularly preferably, a positive first clip connection is formed between the base plate and the cap. According to a further preferred embodiment, a positive second clip connection is formed between the terminal and the cap. The clip connections have the advantage of simple and secure assembly. Furthermore, the clip connections enable non-destructive disassembly of the cap in the event of necessary maintenance and / or repair work.

[0011] Particularly preferably, the first and / or second clip connection are designed such that, when the cap is clipped in, a preload is exerted on the cap. This enables a secure connection between the cap and the terminal and between the cap and the base plate. This is particularly advantageous when the cap is provided as an electrical connection element between the terminal and the base plate, when the terminal is designed as a cathode. For a secure connection, the base plate is preferably designed with a circumferential groove and / or individual embossings to accommodate a first free end region of the cap.

[0012] The terminal preferably has embossing and / or an undercut. The undercut is preferably a protruding, circumferential edge on which a second free end region of the cap is arranged.

[0013] The cap is preferably made of a thermoplastic material. More preferably, the cap is made of a flame-retardant material. The cap is particularly preferably an injection-molded component made of a plastic, in particular a thermoplastic. PPS (polyphenylene sulfide) or PP (polypropylene) is preferably used as the thermoplastic.

[0014] More preferably, the cover assembly comprises a first terminal and a second terminal. The first terminal is the cathode and the second terminal is the anode of the battery cell.

[0015] According to a particularly preferred embodiment of the invention, the sealing element is an elastomer, in particular an electrically conductive elastomer, if the sealing element is arranged on the cathode. The elastomer can be produced, for example, by injection molding in a vulcanization tool in which the base plate and the terminal(s) are inserted as inserts. If the cover assembly comprises two terminals, it is possible to use different materials for the first terminal and the second terminal. In particular, an electrically insulating elastomer is used for the anode, and an electrically conductive elastomer is used for the cathode. The elastomer used is preferably EPDM (ethylene propylene diene rubber) or FKM (fluoroelastomer rubber).However, it is particularly preferred that the materials for the sealing elements at the first and second terminals be the same and preferably made of an electrically non-conductive material. Then, the cap at the cathode can be made of an electrically conductive material, thus establishing electrical contact between the cathode and the base plate. The cap at the anode is made of an electrically non-conductive material.

[0016] The terminal is preferably made entirely of aluminum or an aluminum-copper composite. The base plate is more preferably made of aluminum. The terminals also preferably have a square, particularly rectangular, basic shape.

[0017] Preferably, a peripheral edge area is provided on the terminals, which faces the inside of the cover assembly. This peripheral edge area forms a shoulder on the terminal, against which the sealing element can additionally rest. This allows for an increased contact area between the terminal and the sealing element, enabling even more secure sealing and fixation of the terminal to the base plate.

[0018] The square terminal is preferably designed so that there are no sharp corners. The corners of the square terminal are preferably rounded.

[0019] The sealing element is preferably formed as a single piece. The sealing element can thus be manufactured simply and cost-effectively. Particularly preferably, the sealing element is a component manufactured by injection molding that is molded onto the terminal.

[0020] Particularly preferably, the sealing element is constructed such that the sealing element has an outer region, a central region arranged in the through-opening, and an inner region, wherein the outer region and the inner region extend parallel to the base plate and enclose at least part of the base plate. This allows for a particularly secure fixation of the sealing element to the base plate. In the assembled state, the outer region lies outside the battery cell, and the inner region lies inside the battery cell.

[0021] Further preferably, a surface of the terminal against which the sealing element rests and seals, and / or a surface of the base plate against which the sealing element rests and seals, is formed as a surface-treated surface. The surface-treated surface enables a secure connection between the sealing element and the terminal and / or the base plate. Preferably, the terminal and the base plate are processed with the same surface treatment on the surfaces against which the sealing element rests.

[0022] Further preferably, the surface-treated area is electrically conductive. Electrical conductivity is provided, in particular, at the cathode. This allows the cathode, in particular, to be bonded to the metallic base plate to provide corrosion protection for the cathode.

[0023] The surface treatment of the terminal and / or the base plate on the surfaces in contact with the sealing element is preferably carried out by means of plasma activation and / or application of a primer and / or application of an adhesion promoter and / or mechanical surface treatment, for example, roughening, pickling, plasma treatment, and / or etching. More preferably, the sealing element is an injection-molded component. In particular, this enables a simple, form-fitting adaptation of the sealing element to the terminal and / or the base plate.

[0024] Furthermore, the present invention relates to a battery cell comprising a cover assembly according to the invention.

[0025] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0026] Fig. 1 is a schematic sectional view of a cover assembly according to a first embodiment of the invention,

[0027] Fig. 2 is a schematic, enlarged partial sectional view of a first terminal of the cover assembly of Fig. 1,

[0028] Fig. 3 is a schematic, enlarged partial sectional view of a second terminal of the cover assembly of Fig. 1,

[0029] Fig. 4 is a schematic representation of a battery cell with a cover assembly according to the invention, and

[0030] Fig. 5 is a schematic representation of a battery cell with a cover assembly according to a second embodiment of the invention.

[0031] 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.

[0032] The cover assembly 1 comprises, as shown in Fig. 1, 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.

[0035] 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.

[0036] The first and second terminals have the same geometric structure and are rectangular in shape (see Fig. 4).

[0037] The cover assembly 1 further comprises a first sealing element 5, which seals the first

[0038] Terminal 3 is fixed 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 faces the outside of the cover assembly. The inner region 52 is arranged on an inside of the cover assembly 1.

[0039] As can be seen from Fig. 1, 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.

[0040] 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.

[0041] A surface-treated surface is formed on a surface of the terminal 3 and a surface of the base plate 2, against which the sealing element 5 rests and seals. The surface-treated surface is electrically conductive and can be created, for example, by plasma activation, the application of a primer, an adhesion promoter, or mechanical surface treatment such as roughening, pickling, or etching. The surface-treated surface in the contact areas with the sealing element 5 creates a gas-tight and media-tight bond to the first terminal 3 and the base plate 2 that lasts for the service life of the cover assembly 1.

[0042] The sealing element 5 can be injection-molded onto the first terminal 3 and the base plate 2 by an injection-molding process, which can be inserted, for example, as inserts into an injection-molding tool.

[0043] Furthermore, the cover assembly 1 comprises a cap 11 on the first terminal 3 and a cap 1T on the second terminal 4. The two caps 11, 1T are made of a particularly flame-retardant material and form a protection for the sealing elements 5 and 5'.

[0044] Thus, it is possible for the two sealing elements 5 to be made of the same material, in particular an elastomer. If the elastomer of the sealing element 5 at the first terminal 3 is made of an electrically non-conductive material, the cap 11 can be made of an electrically conductive material and thus establish the electrical connection between the first terminal 3 and the base plate 2 to provide corrosion protection for the first terminal 3.

[0045] As can be seen particularly from Figures 2 and 3, a positive-locking first clip connection 12 is formed between the cap 11 and the base plate 2. A positive-locking second clip connection 13 is formed between the cap 11 and the first terminal 3. Similarly, two clip connections are also provided on the cap 11 at the second terminal 4.

[0046] More precisely, the cap 11 is arranged at a first free end region in a circumferential groove 21 in the base plate 2. A second free end of the cap is arranged at the second clip connection 13 behind an undercut provided by a protruding, circumferential edge 31 of the first terminal 3. This allows a clip connection to be achieved in a simple and secure manner.

[0047] Furthermore, the cap 11 is designed such that, when the cap is mounted, a preload of the cap is created in the first clip connection 12 and in the second clip connection 13. This ensures secure contact between the cap 11, on the one hand, and the base plate 2, on the other hand, and the first terminal 3. Thus, a secure electrical connection can be realized between the first terminal 3 and the base plate 2, particularly at the first terminal 3 designed as a cathode. This also improves the sealing properties of the cap with respect to the base plate 2 and the first terminal 3.

[0048] The preload is achieved, for example, by a small oversize of the two legs of the cap 11 visible in the section.

[0049] It should be noted that the electrical conductivity of the cap 11 on the first terminal 3 can preferably also be achieved by a coating provided on the inside and / or outside with an electrically conductive material, wherein the material for the cap can then be selected from an electrically non-conductive material. As a result, the number of identical parts for the cover assembly can be increased by using identical caps 11 and 1T, and the cap provided on the first terminal 3 can then be provided with an electrically conductive coating. The electrically conductive coating can be provided entirely on the outside and / or inside or only partially on the outside and / or inside.

[0050] The C-shaped design of the sealing element 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 and the base plate 2.

[0051] In particular, the combination of surface treatment on the first and second connection areas 6, 7 between the sealing element 5 and the first terminal 3 or between the sealing element 5 and the base plate 2 ensures a media-tight connection throughout the service life, preventing any leakage through the first and second connection areas 6, 7, either from the inside out or from the outside in. The caps 11, 1T additionally protect the sealing element 5 against external influences, ensuring a secure seal at the through-opening 20 throughout the service life of the cover assembly.

[0052] In addition to sealing the first terminal 3 or the base plate 2, the sealing element 5 also serves as a fixing device for fixing the first terminal 3 in the through-opening 20 of the base plate 2. In particular, by designing the first terminal 3 with the circumferential edge region 30 and a step on the base plate 2, which lies at least partially over the circumferential edge region 30, a positive, secure fixing of the first terminal 3 can be realized.

[0053] A filling opening 8 and a bursting area 9 are also provided in the base plate 2.

[0054] 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 the injection process of the sealing elements 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 element 5.

[0055] The sealing element 5 is formed on the second terminal 4 and the cap 1T is formed on the first terminal 3, since the second terminal 4 is also geometrically designed the same as the first terminal 3.

[0056] As can be further seen from Fig. 1, the two sealing elements 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.

[0057] The contact areas on the anode are preferably pretreated in the same way as the contact areas on the cathode.

[0058] 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 enables a simple connection between the cover assembly 1 and the battery housing 101, for example by welding. Fig. 5 shows an alternative embodiment of a battery cell 100 in which two cell covers 1a and 1b are provided, each of which is arranged on opposite narrow sides of the battery cell 100 and covers 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 embodiment.

Claims

Claims 1. A cover assembly of a battery cell, comprising: a metallic base plate (2), at least one terminal (3, 4) which is arranged in a through-opening (20) of the base plate (2), a sealing element (5) which fastens and seals the terminal to the base plate (2), wherein the sealing element (5) has an outer side, wherein the sealing element (5) is arranged in the through-opening (20) and is designed to seal a first connection region (6) between the terminal (3, 4) and the sealing element (5) and a second connection region (7) between the base plate (2) and the sealing region (5) and to provide a connection between the terminal (3, 4) and the base plate (2), and a cap (11, 1T) which completely covers the sealing element (5) at its region facing the outside.

2. Lid assembly according to claim 1, wherein a positive first clip connection (12) is formed between the base plate (2) and the cap (11, 1T).

3. Cover assembly according to one of the preceding claims, wherein a positive second clip connection (13) is formed between the terminal (3, 4) and the cap (11, 1 T) 4. Lid assembly according to claim 2 or 3, wherein the first clip connection (12) and / or the second clip connection (13) are designed such that in the clipped-in state a prestress is exerted on the cap (11, 1 T).

5. Lid assembly according to one of the preceding claims, wherein the base plate (2) has a circumferential groove (21) or individual embossings for receiving a first free end region of the cap (11, 1 T).

6. Lid assembly according to claim one of the preceding claims, wherein the terminal (3, 4) has embossings and / or an undercut, in particular a projecting, circumferential edge (31), on which a second free end region of the cap (11, 1T) is arranged.

7. Lid assembly according to one of the preceding claims, wherein the cap (11, 1T) is made of a thermoplastic material and / or a flame-retardant material.

8. Cover assembly according to one of the preceding claims, which comprises a first terminal (3) and a second terminal (4).

9. Cover assembly according to one of the preceding claims, wherein the sealing element (5) is made of an elastomeric material, in particular EPDM or FKM.

10. Cover assembly according to one of claims 8 or 9, wherein the cap (11, 1T) on the first terminal (3) is made of an electrically conductive material and the sealing element (5) on the first terminal (3) is made of an electrically non-conductive material and / or wherein the cap (11, 1T) and the sealing element (5) on the second terminal (4) are made of an electrically non-conductive material.

11. Cover assembly according to one of the preceding claims, wherein the terminal (3, 4) is rectangular and in particular has a circumferential edge region (40).

12. Cover assembly according to one of claims 8 and 9, wherein the sealing element (5) on the first terminal (3) is made of an electrically conductive material and the sealing element (5) on the second terminal (4) is made of an electrically non-conductive material.

13. Cover assembly according to claim 12, wherein the cap (11) on the first terminal (3) and the cap (1T) on the second terminal (4) are made of the same material, in particular electrically non-conductive material.

14. Cover assembly according to one of the preceding claims, wherein the sealing element (5) is formed in one piece and in particular wherein the sealing element (5) has an outer region (50), a central region (51) arranged in the through opening (20) and an inner region (52), wherein the outer region and the inner region extend substantially parallel to the base plate (2) and enclose a part of the base plate (2).

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

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