Cover assembly for a battery cell

Abstract

The disclosure relates to a cover assembly for a battery cell (3). The cover assembly comprises a metal frame (11) which is designed to be fastened to a housing (2) of the battery cell (3), a base plate (12) made of an electrically insulating plastic, which is arranged on the metal frame and forms an interlocking and / or frictional connection to the metal frame, an anode (25) which is electrically insulated from the metal frame by the base plate (12), and a high-ohmic current conductor (10) between the anode and the metal frame. The high-ohmic current conductor is designed to provide the housing with electrons of the anode.

Description

[0001] Applicant: Carl Freudenberg KG, 69469 Weinheim

[0002] Cover assembly for a battery cell

[0003] Description

[0004] The invention relates to a cover assembly for a battery cell with a metallic housing, a battery cell and a method for producing a cover assembly.

[0005] During oxidation, ambient humidity (water droplets) acts as an electrolyte on the metallic surface of a battery cell (particularly for prismatic cells and round cells, described below using a prismatic cell as an example), removing electrons from the metal. The positively charged metal ions then react with the ambient oxygen to form the corresponding oxide. Corrosive damage develops on the metal surface. This is particularly critical when battery cells are used for 10-20 years, as in electric vehicles.

[0006] It is an object of the invention to provide a cover assembly for a battery cell which can prevent corrosion on the metallic housing of a battery cell while being inexpensive and easy to manufacture.

[0007] This object is achieved by a cover assembly according to claim 1, as well as by a battery cell according to claim 6 and a method for producing the cover assembly according to claim 7.

[0008] The subclaims show preferred developments of the invention.

[0009] The cover assembly according to the invention with the features of claim 1 comprises a metallic frame, which is designed to be fastened to a housing of the battery cell, in particular a prismatic cell. Furthermore, the cover assembly comprises a base plate made of an electrically insulating plastic, which is arranged on the metallic frame and forms a material-to-material, form-fitting, and / or force-fitting connection with the metallic frame. The form-fitting connection preferably has a toothing, so that the mechanical strength and sealing properties of the connection are improved. The electrically insulating plastic can be a material from the group of thermoplastics, elastomers, thermosets, or thermoplastic elastomers. In particular, the base plate is made of PPS, PPA, EPDM, or PP.The cover assembly further comprises an anode which is electrically insulated from the metallic frame by the base plate. A high-resistance current conductor is arranged between the anode and the metallic frame and is designed to supply electrons from the anode to the housing. The metallic frame is preferably made of the same material as the housing of the battery cell and is connected to it via a welded joint. The conductivity of the high-resistance current conductor is preferably so high that any loss of electrons from the housing due to oxidative reactions is compensated for by the electrical current from the anode to the metallic frame. The high-resistance current conductor can be arranged on the inside of the cover assembly, the outside of the cover assembly, or in the base plate of the cover assembly. The arrangement on the inside enables a structure that is protected from external influences.The high-resistance conductor's external location allows for subsequent installation and easy maintenance. The high-resistance conductor's location within the base plate allows for a protected and space-saving design of the cover assembly.

[0010] The battery cell is preferably a prismatic cell and preferably comprises an accumulator or a supercapacitor.

[0011] The high-resistance conductor preferably comprises an additional electrical resistance component configured to form a predetermined resistance. This allows a defined current to flow from the anode to the metallic frame. Depending on the application, the resistance of the high-resistance conductor can be adapted to the corrosion properties of the environment. The electrical resistance component can be connected to the electrical conductor, for example, by soldering, clamping, or screwing. Furthermore, the electrical resistance component can be integrated into the base plate, for example, by overmolding.

[0012] According to a further preferred embodiment of the invention, the high-resistance current conductor comprises an electrically conductive coating applied to the base plate. This has the advantage that the high-resistance current conductor can be integrated into the cover assembly in a space-saving manner.

[0013] More preferably, the high-resistance conductor comprises an electrically conductive plastic arranged between the anode and the metallic frame. The conductive plastic can be manufactured with the base plate in a multi-component injection molding process. Preferably, sufficient conductive particles are added to the high-resistance conductor until the percolation threshold is reached and the plastic becomes slightly conductive.

[0014] Preferably, the anode is an insert designed to form a positive connection with the base plate. This allows the anode to be easily and cost-effectively integrated into the cover assembly.

[0015] Furthermore, the invention relates to a battery cell, in particular a prismatic cell, comprising a housing and a cover assembly as described above. The high-resistance current conductor, which electrically connects the anode to the housing, can prevent corrosion of the housing.

[0016] The invention also describes a method for producing a cover assembly for a battery cell. The method comprises the steps of arranging a metallic frame and an anode relative to one another. Subsequently, a base plate is produced by injection molding the metallic frame and the anode using an electrically insulating plastic, thereby forming a positive and / or force-fitting connection between the base plate and the anode and a positive connection between the first insert and the base plate. Furthermore, a high-resistance current conductor is attached between the anode and the metallic frame.

[0017] In the method, the high-resistance current conductor is preferably produced by a multi-component injection molding process with a conductive plastic.

[0018] More preferably, the high-resistance current conductor is printed, sputtered or glued onto the base plate.

[0019] Further details, advantages, and features of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawings. It shows:

[0020] Fig. 1 is a schematic sectional view of a prismatic battery cell with a cover assembly according to a first embodiment,

[0021] Fig. 2 is a schematic plan view of the cover assembly according to the first embodiment,

[0022] Fig. 3 is a schematic plan view of the cover assembly according to a second

[0023] embodiment, and

[0024] Fig. 4 is a schematic plan view of the cover assembly according to a third

[0025] Embodiment. A prismatic battery cell 3 with a cover assembly 1 and a method for producing the cover assembly 1 according to a first embodiment of the invention are described in detail below with reference to Figures 1 and 2.

[0026] Figure 1 shows a sectional view through a longitudinal plane of a prismatic battery cell 3. The prismatic battery cell 3 comprises a housing 2, which is closed on an upper side by the cover assembly 1. An electrical energy storage device 4 is arranged within the housing 2.

[0027] The electrical energy storage device 4 comprises at least one negative electrode 7 and one positive electrode 8, which are enclosed by an electrolyte 9. The electrical energy storage device 4 can be, for example, a lithium-ion battery, a sodium-ion battery, or a supercapacitor.

[0028] The cover assembly 1 in Figure 1 has a metallic frame 11, which is attached to the housing 2 of the prismatic battery cell 3 by a welded joint 27. The housing 2 preferably has a wall thickness of 0.3 - 1.0 mm and is made of aluminum.

[0029] A base plate 12 made of an electrically insulating plastic is arranged within the metallic frame 11. A positive connection is formed between the base plate 12 and the metallic frame 11.

[0030] The cover assembly 1 comprises two terminal feedthroughs 21, two filling openings 24, and a bursting area 22 with a first bursting area 22a and a second bursting area 22b. The two terminal feedthroughs 21, the two filling openings 24, and the bursting area 22 are designed as inserts 31, which are overmolded with the electrically insulating plastic of the base plate 12. The outer contour of the inserts 31 enables the formation of positive connections between the base plate 12 and the inserts 31.

[0031] The terminal bushings 21 have a U-shaped cross-section, with the electrically insulating plastic of the base plate 12 flowing between the two legs of the U-shaped cross-section to form a positive connection. The U-shaped cross-section is aligned coplanar to the base plate 12. An outer side of the U-shaped cross-section of the terminal bushing 21 is directed towards the interior of the prismatic battery cell 3. One terminal bushing 21 is connected to the negative electrode 7, thus forming an anode 25, and another terminal bushing 21 is connected to a positive electrode 8, thus forming a cathode 26. The other outer side of the U-shaped cross-section of the terminal bushing 21 is directed outwards and is designed to be contacted with an electrical conductor. The anode 25 is preferably made of copper. The cathode is preferably made of aluminum.

[0032] The terminal bushings 21 are arranged in the longitudinal direction R1 at two lateral ends near the metallic frame 11. The distance to the metallic frame 11 must be large enough to prevent voltage breakdown from the terminal bushing 21 to the housing.

[0033] At a first end of the cover assembly 1 in the longitudinal direction R1, a high-resistance current conductor 10 is formed between the anode 25 and the metallic frame 11. The high-resistance current conductor 11 is configured to supply electrons to the housing 2 via the metallic frame 11 in order to prevent corrosion of the housing 2.

[0034] The plastic of the high-resistance current conductor 10 is filled with conductive particles so that the percolation threshold of the plastic is just exceeded, resulting in a slightly conductive plastic. By making the high-resistance current conductor 10 from a conductive plastic, the high-resistance current conductor 10 replaces the base plate 12 at the first end of the cover assembly 1.

[0035] The bursting area 22 is arranged centrally in the cover assembly 1. The bursting area 22 has a stepped structure, forming a first bursting area 22a and a second bursting area 22b. The first bursting area 22a has a smaller thickness than the second bursting area 22b. Thus, the compressive strength of the first bursting area 22a is lower than the compressive strength of the second bursting area 22b, so that in the event of a cell failure, the first bursting area 22a opens first to relieve increasing pressure from the interior of the prismatic battery cell 3. The second bursting area 22b can then open if the pressure inside the prismatic battery cell 3 continues to rise. The first bursting region 22a is arranged within the second bursting region 22b, wherein a notch is formed between the first bursting region 22a and the second bursting region 22b, which notch forms a defined failure point.A notch is also formed on the outer circumference of the second bursting area 22b, which forms a defined failure point for the second bursting area 22b.

[0036] The filling opening 24 is arranged in the base plate 12 between the bursting area 22 and the two terminal feedthroughs 21. One filling opening 24 is used to introduce the electrolyte 9 into the prismatic battery cell 3, and the other filling opening 24 is used to expel the gas displaced by the electrolyte 9. For this purpose, the filling openings 24 have a cylindrical through-opening which is designed to be closed by a plug. A gas permeation-reducing coating 23 is applied to an outer side of the base plate 12 of the cover assembly 1, which is oriented perpendicular to the transverse direction R2. This coating prevents gas exchange between the electrical energy storage device 4 and the environment outside the prismatic battery cell 3 when the prismatic battery cell 3 is filled.

[0037] The cover assembly 1 according to the first embodiment is manufactured using an injection molding process. For this purpose, in a first step, the metallic frame 11, the first insert 31, the second insert 32, and the third insert 33 are inserted into a mold of an injection molding tool, aligned, and fixed. Finally, an electrically insulating plastic and an electrically conductive plastic are introduced into the mold, with the plastic coming into contact with the metallic frame 11 and the inserts 31 and curing. The cured electrically insulating plastic forms the base plate 12, which is connected to the metallic frame 11 and the inserts 3 by a positive and / or non-positive connection. The electrically conductive plastic forms the high-resistance current conductor 10.

[0038] Figure 2 shows a top view of the cover assembly 1 of the prismatic battery cell 3 from Figure 1.

[0039] The metallic frame 11 has a rectangular shape and forms the outer edge of the cover assembly 1. The base plate 12, on which the gas permeation-reducing coating 23 is applied, is arranged within the frame.

[0040] The terminal feedthroughs 21, filling openings 24, and the bursting area 22 are distributed centrally along a longitudinal axis XX and spaced from the metallic frame 11. The bursting area 22 has an oval shape in plan view.

[0041] At the first end of the cover assembly 1 in the longitudinal direction R1, the electrically conductive plastic, which forms the high-resistance current conductor 10, is arranged between the anode 26 and the metallic frame 11. The electrically conductive plastic is also arranged between the legs of the U-shaped terminal bushing 21 and adjoins the base plate 12 there.

[0042] Figure 3 shows a schematic plan view of the cover assembly 1 of the prismatic battery cell 3 according to a second embodiment.

[0043] The cover assembly 1 according to the second embodiment is similar to the cover assembly 1 according to the first embodiment. In this case, the cover assembly 1 in Figure 3 only has one filling opening 24 between the burst opening 22 and the cathode 25. Furthermore, the high-resistance current conductor 10 of the second embodiment differs from the first embodiment. The high-resistance current conductor 10 in Figure 3 has a resistance component 13 which is arranged between two electrical conductors of the high-resistance current conductor 13. The resistance component 13 is an ohmic resistor which limits the current flowing between the anode 25 and the metallic frame 11. In this case, an electrical current can be set between the anode 25 and the metallic frame 11 which is just high enough to prevent corrosion of the housing 2.

[0044] Figure 4 shows a schematic plan view of the cover assembly 1 of the prismatic battery cell 3 according to a third embodiment.

[0045] The cover assembly 1 according to the third embodiment is similar to the cover assembly 1 according to the second embodiment and differs only in the design of the high-resistance current conductor 10.

[0046] The high-resistance current conductor in Figure 4 is applied as an electrically conductive coating 14 to the base plate 12 and establishes an electrical connection between the anode 25 and the metallic frame 11. The conductive coating 14 has a high ohmic resistance, so that only a very low electrical current flows between the anode 25 and the metallic frame 11. The conductive coating 14 is preferably printed, sputtered, or glued to the base plate 12.

[0047] In addition to the above written description of the invention, reference is hereby explicitly made to the graphic representation of the invention in the figures for its supplementary disclosure.

Claims

Patent claims 1 . Cover assembly for a battery cell (3), comprising . a metallic frame (11) which is adapted to be attached to a housing (2) of the battery cell (3), . a base plate (12) made of an electrically insulating plastic, which is arranged on the metallic frame (11) and forms a positive and / or non-positive and / or material connection with the metallic frame (11), . an anode (25) which is electrically insulated from the metallic frame (11) by the base plate (12), and . a high-resistance current conductor (10) between the anode (25) and the metallic frame (11), . wherein the high-resistance current conductor (10) is arranged to provide electrons of the anode (25) to the housing (2).

2. Cover assembly according to claim 1, wherein the high-resistance current conductor (10) comprises an additional electrical resistance component (13) which is designed to form a predetermined resistance.

3. Cover assembly according to one of the preceding claims, wherein the high-resistance current conductor (10) comprises an electrically conductive coating (14) which is applied to the base plate (12). 4 Cover assembly according to one of the preceding claims, wherein the high-resistance current conductor (10) comprises an electrically conductive plastic which is arranged between the anode (25) and the metallic frame (11).

5. Cover assembly according to one of the preceding claims, wherein the anode (25) is an insert (31) which is designed to form a positive connection with the base plate (12).

6. Battery cell comprising a housing (2) and a cover assembly (1) according to one of the preceding claims, wherein the cover assembly (1) comprises a high-resistance current conductor (10) which is configured to provide the housing (2) with electrons of an anode (25).

7. A method for producing a cover assembly (1) for a battery cell (3), comprising the steps: - arranging a metallic frame (11) and the anode (25) relative to each other, and - producing a base plate (12) by an injection molding process on the metallic frame (11) and on the anode (25) with an electrically insulating plastic, so that a positive and / or non-positive connection is formed between the base plate (12) and the anode (25) and a positive connection is formed between the first insert part (31) and the base plate (12), and - Attaching a high-resistance current conductor (10) between the anode (25) and the metallic frame (11).

8. The method according to claim 7, wherein the high-resistance current conductor (10) is manufactured by a multi-component injection molding process with a conductive plastic.

9. The method according to claim 7, wherein the high-resistance current conductor (10) is printed onto the base plate (12) or wherein the high-resistance current conductor (10) is sputtered onto the base plate (18) or wherein the high-resistance current conductor (10) is applied to the base plate (18) is glued on.

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