Cover assembly for a battery cell

Abstract

The invention relates to a cover assembly for 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); and a sealing element (5, 5') which secures and seals the terminal to the base plate (2), wherein the sealing element (5, 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 element (5, 5'), and to establish a connection between the terminal (3, 4) and the base plate (2).

Description

[0001] Battery cell cover assembly

[0002] Description

[0003] The invention relates to a cover assembly 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, 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 and the cell chemistry from the environment. The cover assembly should also enable the connection of electrodes inside the battery cell and electrical contact outside the battery cell. Previous systems have been sealed with potting compounds, for example. However, these can age over their service life, causing shrinkage and opening up leakage paths.In particular, oxygen from the environment is considered critical, as it can diffuse into the interior of the battery and significantly reduce the service life of the electrolyte.

[0005] It is an object of the invention to provide an improved cover assembly and a battery cell with such a cover assembly while being simple and cost-effective to manufacture and at the same time providing comprehensive tightness.

[0006] This object is achieved by a cover assembly having the features of claim 1 and a battery cell having the features of claim 16.

[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 of enabling significantly improved sealing in the area of ​​the electrical poles that 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 through the gap at the pole feedthroughs can be prevented according to the invention.

[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.

[0010] 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, which is molded onto the terminal and the base plate.

[0011] 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.

[0012] 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.

[0013] Further preferably, the surface-treated area is electrically conductive. The electrical

[0014] Conductivity is provided, in particular, at the cathode. This allows the cathode to be electrically connected to the metallic base plate to provide corrosion protection for the cathode.

[0015] The surface treatment of the terminal and / or the base plate on the surfaces which are 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 and / or pickling and / or etching.

[0016] More preferably, the sealing element is an injection-molded component. In particular, this allows for a simple, form-fitting adaptation of the sealing element to the terminal and / or the base plate.

[0017] Further preferably, the cover assembly comprises at least a first terminal and, depending on the design of the cell storage device, also a second terminal. According to the counting method used here, the first terminal is the cathode and the second terminal is the anode of the battery cell.

[0018] 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 sealing elements on 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 following can be used as elastomers: FFKM, FKM, NR, IR, HR, CR, ECO, EPDM, EPM, NBR, HNBR, PU, ​​ACM, AEM, VMW, FVMQ, thermoplastic elastomers, and blends thereof; preferably EPDM (ethylene propylene diene rubber) or FKM (fluoroelastomer rubber) is used.

[0019] According to an alternative embodiment of the invention, the sealing element is a plastic, in particular a thermoplastic. To make the thermoplastic electrically conductive at the cathode, it is possible to add additives that ensure the electrical conductivity of the thermoplastic. The sealing element made of thermoplastic is preferably also injection-molded onto the terminal(s) and / or the base plate. The thermoplastic is preferably PPS (polyphenylene sulfide) or PP (polypropylene). Thermosets and potting materials are also preferred. When using a thermoplastic as the sealing element, an elastomeric, flexible layer is preferably additionally provided between the thermoplastic and the terminal and / or the thermoplastic and the base plate.If electrical conductivity between the terminal and the base plate is desired, the elastomeric flexible layer can also be made electrically conductive, for example by additives.

[0020] The terminal is preferably made entirely of aluminum or of an aluminum-copper composite or of copper-coated aluminum or of stainless steel. The base plate is more preferably made of aluminum or stainless steel. More preferably, the terminals have a square, in particular rectangular, basic shape. A circumferential edge region is preferably provided on the terminals, which is directed towards the inside of the cover assembly. The circumferential edge region forms a shoulder on the terminal, against which the sealing element can additionally rest. This makes it possible to increase the contact surface between the terminal and the sealing element, so that an even more secure sealing and fixing of the terminal to the base plate is possible.

[0021] The square terminal is preferably designed so that there are no sharp corners. The corners of the square terminal are preferably rounded.

[0022] Preferably, the cover assembly comprises an insulating plate made of a non-conductive plastic that is clipped to the base plate, or an insulating plate made of a non-conductive plastic that is bonded to the base plate in an injection molding process.

[0023] Furthermore, the present invention relates to a battery cell comprising a cover assembly according to the invention.

[0024] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0025] Fig. 1 is a schematic sectional view of a cover assembly according to a first embodiment of the invention,

[0026] Fig. 2 is a schematic, enlarged partial sectional view of a first terminal of the cover assembly of Fig. 1,

[0027] Fig. 3 is a schematic, enlarged partial sectional view of a second terminal of the cover assembly of Fig. 1, Fig. 4 is a schematic representation of a battery cell with a cover assembly according to the invention, and

[0028] Fig. 5 is a schematic representation of a battery cell with a cover assembly according to a second embodiment of the invention.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] The first and second terminals have the same geometric structure and are rectangular in shape (see Fig. 4).

[0034] 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.

[0035] 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.

[0036] The first terminal 3, as further shown in Fig. 1, has a main area and a circumferential 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. A surface-treated area 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 area is electrically conductive and can be produced, for example, by plasma activation or application of a primer or application of an adhesion promoter or mechanical surface treatment such as roughening, pickling, or etching.The surface-treated surface at the contact areas with the sealing element 5 creates a gas-tight and media-tight connection to the first terminal 3 and the base plate 2 that lasts for the entire service life of the cover assembly 1.

[0037] 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.

[0038] The material of the sealing element 5 can be an electrically conductive elastomer, for example, EPDM or FKM. The sealing element 5 is electrically conductive at the first terminal 3, which forms the cathode of the cover assembly 1, in order to provide corrosion protection for the first terminal 3. Alternatively, an electrically conductive thermoplastic can also be provided as the material for the sealing element 5.

[0039] 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.

[0040] In particular, by combining the surface treatment on the first and second connecting regions 6, 7 between the sealing element 5 and the first terminal 3 or the sealing element 5 and the base plate 2, a media-tight connection can be ensured over the service life, so that no leakage is possible via the first and second connecting regions 6, 7, neither from the inside to the outside nor from the outside to the inside.

[0041] 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.

[0042] The base plate 2 also includes a filling opening 8 and a bursting area 9. 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. 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.

[0043] On the second terminal 4, the sealing element is designated by reference numeral 5'. The second sealing element 5' is geometrically identical to the first sealing element 5, since the second terminal 4 is also geometrically identical to the first terminal 3. However, the second sealing element 5' is made of a material that does not have electrically conductive properties. Thus, the material of the second sealing element 5' is electrically insulating.

[0044] Alternatively, the same electrically insulated plastic can be used on the first and second terminals 3, 4 and an electrically conductive material is sprayed onto the material on the first terminal (cathode), so that a 2K material is applied to the cathode.

[0045] 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 sealing element 5, 5' and thus to the base plate 2.

[0046] If a thermoplastic is used as the material for the sealing elements 5, 5', PPS or PP is preferably used.

[0047] It should also be noted that when using a thermoplastic as the material for the sealing elements, an elastomeric, flexible layer can additionally be provided on both contact areas of the sealing elements 5, ie, on the contact area to the terminals 3, 4 and on the contact area to the base plate 2.

[0048] The contact areas on the anode are preferably pretreated in the same way as the contact areas on the cathode.

[0049] 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, 5') which fastens and seals the terminal to the base plate (2), wherein the sealing element (5, 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 element (5, 5') and to provide a connection between the terminal (3, 4) and the base plate (2).

2. Cover assembly according to claim 1, wherein the sealing element (5, 5') is formed in one piece.

3. Lid assembly according to claim 2, wherein the sealing element (5, 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).

4. Cover assembly according to one of the preceding claims, wherein a surface of the terminal (3, 4) against which the sealing element (5, 5') rests and seals, and / or a surface of the base plate (2) against which the sealing element (5, 5') rests and seals, is formed as a surface-treated surface.

5. The cover assembly of claim 4, wherein the surface-treated surface is electrically conductive.

6. The lid assembly of claim 4 or 5, wherein the surface-treated surface is a plasma-activated surface, a primer-treated surface, a bond coat-coated surface, or a mechanically surface-treated surface.

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

8. Lid assembly according to one of the preceding claims, wherein the sealing element (5, 5') is an injection-molded component.

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

10. Lid assembly according to one of claims 1 to 8, wherein the sealing element (5, 5') is a plastic, in particular a thermoplastic, in particular PPS or PP.

11. Cover assembly according to claim 10, wherein an elastomeric layer is arranged between the sealing element (5, 5') and the terminal (3, 4) and / or between the sealing element (5, 5') and the base plate (2).

12. Cover assembly according to one of claims 7 to 11, wherein the sealing element 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 one of the preceding claims, wherein the terminal (3, 4) is rectangular and in particular has a circumferential edge.

14. Cover assembly according to one of claims 7 to 13, wherein the first terminal (3) is made of aluminum or copper or stainless steel and the second terminal (4) is made of an aluminum-copper composite or copper or copper-coated aluminum or stainless steel and the base plate is made of aluminum or stainless steel.

15. Cover assembly according to one of the preceding claims, comprising an insulating plate (10) made of a non-conductive plastic, which is clipped to the base plate (2), or an insulating plate (10) made of a non-conductive plastic, which is connected to the base plate (2) in an injection molding process.

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

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