Cover assembly for a prismatic cell with rupturing region

Abstract

The invention relates to a cover assembly for a prismatic cell, comprising a metal frame which is designed to be attached to a housing of the prismatic cell. The cover assembly further comprises a base plate which is made of an electrically insulating plastic, is arranged on the metal frame and forms an interlocking and / or frictional connection with the metal frame. The cover assembly also comprises a rupturing region, which is located on the base plate. The rupturing region comprises a point of weakness which is designed to open when activated by pressure and / or temperature.

Description

[0001] Applicant: Carl Freudenberg KG, 69469 Weinheim

[0002] Cover assembly for a prismatic cell with burst area

[0003] Description

[0004] The invention relates to a cover assembly for a prismatic cell, as well as a cell arrangement with a prismatic cell.

[0005] Currently, prismatic cells have a burst zone that opens in the event of cell failure (thermal runaway) under pressure and temperature control, allowing the burning cell chemistry within the prismatic cell to escape and dissipate in a controlled manner. Without a burst zone, the pressure and temperature inside the cell would build up to such an extent in the event of cell failure that an uncontrolled release of the cell chemistry would occur. This uncontrolled release is critical because this process can be explosive and neighboring components can be affected. This can also trigger cell failure in neighboring battery cells, resulting in a chain reaction and the entire cell assembly burning down. State-of-the-art burst zones consist of many components that are assembled with great effort.There is a risk of assembly errors, leaks and age-related functional changes.

[0006] It is an object of the invention to provide an improved cover assembly and an improved cell arrangement with a prismatic cell with simple and cost-effective manufacture.

[0007] This object is achieved by a cover assembly having the features of claim 1, as well as by a cell arrangement having the features of claim 12.

[0008] The cover assembly according to the invention for a prismatic cell with the features of claim 1 comprises a metallic frame, which is designed to be attached to a housing of the 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 positive and / or non-positive connection with the metallic frame. The cover assembly also comprises a bursting area, which is arranged on the base plate. The bursting area has a weak point, which is designed to open under pressure and / or temperature activation. The cover assembly according to the invention enables simple, cost-effective, and reliable integration of the bursting area into a prismatic cell.In particular, the bursting area can be integrated directly into the cover assembly in an injection molding process, eliminating complex and error-prone assembly steps.

[0009] The metal frame can be a stamped part or an extruded and formed profile. Alternatively, the metal frame can also be a metal casting into which functional surfaces are integrated.

[0010] The base plate is preferably made of a polymer which is fiber-filled and comprises flame retardants and / or other fillers to improve thermal conductivity.

[0011] The prismatic cell is preferably an accumulator or a supercompensator.

[0012] The subclaims show preferred developments of the invention.

[0013] Preferably, the burst zone is integrated into the base plate through a reduced wall thickness. This allows the burst zone to be integrated into the cover assembly without additional components. The burst zone can be integrated directly into the base plate, for example, using an injection mold. Alternatively, the reduced wall thickness can be integrated into the base plate through a stamping process.

[0014] Further preferably, the cover assembly comprises an insert that is secured to the base plate in a form-fitting and / or force-fitting and / or material-fitting manner. The insert preferably includes the bursting area. Thus, the bursting area can be pre-integrated into an insert, which is then secured to the base plate, preferably in an injection-molding process. Further preferably, other components of the cover assembly, such as terminal feedthroughs or filling openings, are designed as inserts, thus enabling simple and cost-effective production of the cover assembly.

[0015] The bursting area particularly preferably has a notch. The notch forms a defined weak point at which the bursting area opens in the event of cell failure. The temperature and / or pressure resistance of the cell can be defined by the depth of the notch. According to a further preferred embodiment of the invention, the cover assembly comprises a first bursting area and a second bursting area. The pressure resistance and / or temperature resistance of the second bursting area is higher than the pressure resistance and / or temperature resistance of the first bursting area. The first bursting area preferably opens at a pressure of 600 kPa and the second bursting area at a pressure of 800 kPa. The first bursting area thus allows gases to be released when cell failure begins. The second bursting area serves for the targeted release of the combustion gases in the event of advanced cell failure or cell burning.The second burst zone enables a defined diversion of the combustion gases into an area where only minimal damage occurs and, ideally, no further propagation to other prismatic cells occurs. The cover assembly according to the invention facilitates the integration of a complex burst zone with different sub-areas.

[0016] The second bursting area is preferably configured to form a larger opening than the first bursting area. In particular, a second diameter of the second bursting area is larger than a first diameter of the first bursting area. Thus, a bursting area can be integrated into the lid assembly, which, in the event of a cell failure, enables the cell chemistry to be released as needed through a first or second bursting area.

[0017] More preferably, the first bursting area is arranged within the second bursting area, thereby enabling a compact design.

[0018] Alternatively or additionally, the first bursting area is preferably arranged adjacent to the second bursting area. The adjacent arrangement of the first bursting area and the second bursting area enables a reliable and independent opening behavior of the two bursting areas.

[0019] The bursting zone preferably comprises a film. The film can preferably also serve as a gas permeation-reducing layer of the lid assembly, preventing gas exchange between the interior of the prismatic cell and the atmosphere.

[0020] More preferably, the film is pre-embossed. Particularly preferably, the film is attached to the inside of the base plate. A pre-embossed film enables temperature- and / or pressure-activated opening of the film in the bursting area. The arrangement of the film on the inside of the base plate protects the film from external influences and reduces the risk of gas inclusions in the prismatic cell. Preferably, the cover assembly comprises a rib arranged adjacent to the bursting area to define an outflow direction from the bursting area. The rib can reinforce the base plate and the cover assembly. Furthermore, the arrangement of the rib between the terminal feedthrough and the bursting area enables protection of the electrical elements from a medium that may escape from the bursting area in the event of a cell failure.

[0021] Furthermore, the invention relates to a cell arrangement comprising a prismatic cell with a previously described cover assembly and a sensor. The sensor is configured to detect fluid escaping from the bursting area in order to issue a hazard warning. Thus, an occurring cell failure can be detected early, giving the operator of the cell arrangement more time to react to subsequent cell burning or propagation. The sensor is preferably an H2 sensor.

[0022] 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:

[0023] Fig. 1 is a schematic sectional view of a cell arrangement with a prismatic cell with a cover assembly according to a first embodiment,

[0024] Fig. 2 is a schematic sectional view of a prismatic cell with a first cover assembly and a second cover assembly, according to a second embodiment,

[0025] Fig. 3 is a schematic sectional view of a prismatic cell with a

[0026] Cover assembly according to a third embodiment, and

[0027] Fig. 4 is a schematic plan view of a cover assembly according to the third

[0028] Example of implementation.

[0029] A cell arrangement 100 with a cover assembly 1 according to a first embodiment of the invention is described in detail below with reference to Figure 1.

[0030] Figure 1 shows a sectional view through a longitudinal plane of a prismatic cell 3. The prismatic 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.

[0031] 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.

[0032] The cover assembly 1 in Figure 1 comprises a metallic frame 11, which is attached to the housing 2 of the prismatic 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.

[0033] 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.

[0034] The cover assembly 1 comprises two terminal feedthroughs 21, two filling openings 24, and a bursting area 22. 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.

[0035] 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 with 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 cell 3. One terminal bushing 21 is connected to the negative electrode 7, and another terminal bushing 21 is connected to a positive electrode 8. 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.

[0036] 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.

[0037] 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 temperature and pressure resistance of the first bursting area 22a is lower than the temperature and pressure resistance of the second bursting area 22b, so that in the event of cell failure, the first bursting area 22a opens first to relieve increasing pressure from the interior of the prismatic cell. The second bursting area 22b can then open if the pressure inside the prismatic cell continues to rise.

[0038] The first bursting region 22a has a first diameter D1, which is smaller than the second diameter D2 of the second bursting region 22b. The first bursting region 22a is arranged centrally within the second bursting region 22b.

[0039] A notch 10 is formed between the first bursting area 22a and the second bursting area 22b, forming a defined weak point. A notch 10 is also formed on the outer periphery of the second bursting area 22b, forming a defined weak point for the second bursting area 22b.

[0040] Between the bursting area 22 and the terminal feedthroughs 21, a rib 13 is formed, which is part of the base plate 12 and is oriented perpendicularly thereto. The rib 13 defines an outflow direction from the bursting area 22.

[0041] The filling opening 24 is arranged in the base plate 12 between the two ribs 13 and the two terminal feedthroughs 21. One filling opening 24 is used to introduce the electrolyte 9 into the prismatic cell 3. 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 closure.

[0042] On an outer side of the base plate 12 of the cover assembly 1, which is oriented perpendicular to the transverse direction R2, a gas permeation-reducing film 23b is applied, which prevents a gas exchange between the electrical energy storage device 4 and the environment outside the prismatic cell 3 when the prismatic cell 3 is filled.

[0043] The cell arrangement 100 in Figure 1 comprises, in addition to the prismatic cell 3 with the cover assembly 1, a sensor 40 configured to detect fluid escaping from the bursting area 22 in order to issue a hazard warning. For example, the operator of the cell arrangement 100 can be warned acoustically or visually. Preferably, the cell arrangement 100 comprises a plurality of prismatic cells 3 arranged adjacent to one another. Thus, the cell arrangement 100 can form, for example, a battery module in an electric vehicle.

[0044] The cover assembly 1 according to the first embodiment is preferably manufactured using an injection molding process. For this purpose, in a first step, the metallic frame 11 and the inserts 31 are inserted into a mold of an injection molding tool, aligned, and secured. Finally, an electrically insulating plastic is introduced into the mold, where the plastic comes into contact with the metallic frame 11 and the inserts 31 and hardens. The hardened plastic forms the base plate 12, which is connected to the metallic frame 11 and the inserts 31 by a positive and / or non-positive connection.

[0045] Figure 2 shows a prismatic cell 3 with the housing 2 and a first cover assembly 5 connected thereto according to a second embodiment and a further second cover assembly 6.

[0046] The first cover assembly 5 is attached to a first end of the housing 2 in the transverse direction R2. The second cover assembly 6 is attached to a second end of the housing 2 in the transverse direction R2. The first cover assembly 5 and the second cover assembly 6 are arranged parallel to each other.

[0047] The first cover assembly 5 and the second cover assembly 6 both have a stamped metallic frame 11, which is connected to the housing 2 of the prismatic cell 3 via a welded joint 27. The metallic frame 11 is connected to the base plate 12 in a force-fitting manner and in the longitudinal direction R1 in a form-fitting manner.

[0048] The first lid assembly 5 has a filling opening 24 and a burst area 22, which are directly integrated into the base plate 12 through its shape. The burst area 22 has been directly integrated into the shape of the base plate 12 in an injection molding process.

[0049] The bursting area 22 in the first cover assembly 5 in Figure 2 has a first bursting area 22a, which is arranged adjacent to the second bursting area 22b on the inside of the base plate 12. Notches 10 are arranged between the first bursting area 22a and the base plate 12, as well as between the second bursting area 22b and the base plate 12, forming a defined weak point. The wall thickness of the base plate 12 is less in the area of ​​the first bursting area 22a than in the area of ​​the second bursting area 22b, so that the first bursting area 22a has a lower compressive strength and temperature resistance than the second bursting area 22b.

[0050] Furthermore, the first cover assembly 5 has a terminal feedthrough 21, which is connected to the negative electrode 7 in the interior of the prismatic cell 3, so that the terminal feedthrough 21 of the first cover assembly 5 forms an anode. The anode is preferably made of copper in lithium-ion batteries and of aluminum in sodium-ion batteries. The second cover assembly 6 has a filling opening 24 and a terminal feedthrough 21. The filling opening 24 is integrated into the base plate 12 due to its shape. The terminal feedthrough 21 is designed as a first insert 31 and is connected to the positive electrode 8 inside the prismatic cell 3. The terminal feedthrough 21 of the second cover assembly 6 thus forms a cathode.

[0051] The pole bushings 21 of the first and second cover assemblies 5, 6 are positively connected to the base plate 12 with a dovetail-shaped connection in the longitudinal direction R1 and transverse direction R2.

[0052] The filling opening 24 of the first cover assembly 5 is arranged at a first end in the longitudinal direction R1. The filling opening 24 of the second cover assembly 5 is arranged at a second end in the longitudinal direction R1. Thus, when the prismatic cell 3 is geodetically aligned with the longitudinal direction R1 facing upwards, the electrolyte 9 can be introduced from below into the interior of the prismatic cell 3 via the filling opening 24 in the first cover assembly 5, while the displaced gas can escape through the filling opening 24 in the second cover assembly 6.

[0053] Figure 3 shows a third embodiment of the prismatic cell 3 with the housing 2, which is closed by the cover assembly 1. The bursting area 22, which comprises a pre-embossed bursting foil 23a, is arranged centrally in the cover assembly 1.

[0054] The cover assembly 1 comprises two terminal feedthroughs 21, which are designed analogously to the terminal feedthroughs 21 in the first embodiment. The metallic frame 11 has a circular cross-section and forms a positive connection with the base plate 12 via the welded joint 27.

[0055] The filling openings 24 are integrated into the shape of the base plate 12 and arranged adjacent to the terminal feedthroughs 21. Between the filling openings 24 and the bursting area 22, a rib 13 is arranged, which defines the outflow direction from the bursting area 22 and improves the mechanical strength of the base plate 12.

[0056] The bursting region 22 according to the third exemplary embodiment has a recess 15 in the base plate 12, which is closed on the inside of the base plate 12 with the bursting foil 23a. The bursting foil 23a is preferably integrally connected to the base plate 12. By placing the bursting foil 23a on the inside of the base plate 12, the bursting foil 23a is in direct contact with the electrolyte 9 and prevents an additional cavity from forming on the inside of the prismatic cell 3, in which a gas can deposit. The bursting foil 23a at the bursting region 22 extends in the longitudinal direction R1 between the ribs 13. The bursting foil 23a has an embossed portion 14 in the bursting region 22, which locally reduces the thickness of the bursting foil 23a, thereby forming a weak point. The embossing 14 enables a defined temperature and pressure activated opening of the bursting film 23a in the bursting area 22.

[0057] Between the ribs 13 and the metallic frame 11, the gas permeation-reducing film 23b is attached to the outside of the base plate 12, which film is designed to reduce gas permeation through the base plate 12.

[0058] Figure 4 shows a top view of the cover assembly 1 according to the third embodiment of the prismatic cell 3 from Figure 3.

[0059] The metallic frame 11 has a rectangular shape and forms the outer edge of the cover assembly 1.

[0060] The terminal feedthroughs 21, filling openings 24, and the bursting area 22 are distributed centrally along a longitudinal axis XX. The inserts 31 are spaced apart from the metallic frame 11. The base plate 12 has, in plan view, the oval recess 15, which is part of the bursting area 22. The bursting foil 23a is arranged in the recess 15 on the inside of the base plate 12.

[0061] The bursting foil 23a has, in plan view, the embossing 14 with a herringbone pattern.

[0062] The ribs 13 extend from one side of the metallic frame 11 to an opposite side of the metallic frame 11. The ribs 13 are aligned perpendicular to the longitudinal axis XX. Within the metallic frame 11, the gas permeation-reducing film 23b is attached between the ribs 13 on the base plate 12.

[0063] 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 (1) for a prismatic cell (3), comprising . a metallic frame (11) adapted to be fixed to a housing (2) of the prismatic 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 connection with the metallic frame (11), and . a bursting area (22) arranged on the base plate (12), . wherein the bursting area (22) has a weak point which is designed to open in a pressure- and / or temperature-activated manner.

2. Cover assembly (1) according to claim 1, wherein the bursting area (22) is integrated into the base plate (12) by a reduced wall thickness.

3. Lid assembly (1) according to claim 1, comprising an insert part (31) which is fastened to the base plate (12) in a form-fitting and / or force-fitting and / or material-fitting manner, wherein the insert part (31) comprises the bursting region (22).

4. Lid assembly (1) according to one of the preceding claims, wherein the bursting region (22) has a notch (10).

5. Lid assembly (1) according to one of the preceding claims, wherein the lid assembly (1) comprises a first bursting region (22a) and a second bursting region (22b), wherein the compressive strength and / or temperature strength of the second bursting region (22b) is higher than the compressive strength and / or temperature strength of the first bursting region (22a).

6. Lid assembly (1) according to claim 5, wherein the second burst area (22b) is configured to form a larger opening than the first burst area (22a).

7. Lid assembly (1) according to claim 5 or 6, wherein the first bursting region (22a) is arranged within the second bursting region (22b).

8. Lid assembly (1) according to claim 5 or 6, wherein the first bursting region (22a) is arranged adjacent to the second bursting region (22b).

9. Lid assembly (1) according to one of the preceding claims, wherein the bursting region (22) comprises a film (23).

10. Lid assembly (1) according to claim 9, wherein the film (23) is pre-embossed and / or wherein the film (23) is attached to the inside of the base plate (12).

11. Lid assembly (1) according to one of the preceding claims, comprising a rib (13) arranged adjacent to the burst area (22) to define an outflow direction from the burst area (22).

12. Cell arrangement (100) comprising a prismatic cell (3) with a lid assembly (1) according to one of the preceding claims and a sensor (40) which is arranged to detect a fluid escaping from the bursting area (22) in order to issue a danger message.

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