BATTERY CELL CLOSURE STRIP FOR A BATTERY CELL OF PRISMATIC OR OF POUCH-TYPE DESIGN, AND BATTERY CELL

Abstract

A battery cell closure strip for a battery cell of prismatic or of pouch-type design is disclosed. A main body has a degassing duct which extends along the vertical axis of the battery cell closure strip from an inner side of the battery cell closure strip to the outer side of the battery cell closure strip. The degassing duct is closed by means of a media-operated sealing element during regular operation of the battery cell closure strip. The sealing element opens the degassing duct when a predefined limit pressure of the battery cell is reached. An emergency degassing duct has an opening cross section through which media can flow that is at least 10 times larger than that of the degassing duct and which is closed by a bursting valve which opens the emergency degassing duct when a bursting pressure is reached or exceeded.

Claims

1. A battery cell closure strip for a battery cell of pouch-type design, comprising: a main body having: a degassing duct which extends along the vertical axis V of the battery cell closure strip from an inner side to an outer side thereof, wherein the degassing duct is closed during normal operation of the battery cell closure strip by means of a media-operated sealing element which opens the degassing duct when a predefined internal limit pressure P.sub.lim is reached; and having an emergency degassing duct which has an opening cross section through which media can flow that is at least 10 times larger than that of the degassing duct, and which is closed by means of a bursting valve which opens the emergency degassing duct when a nominal internal bursting pressure P.sub.crit, where P.sub.crit>P.sub.lim, is reached or exceeded; wherein the bursting valve comprises a bursting membrane.

2. The battery cell closure strip of claim 1, wherein the bursting valve comprises a bursting cap.

3. The battery cell closure strip of claim 2, wherein the bursting cap consists of a rubber-elastically deformable material.

4. The battery cell closure strip of claim 1, wherein the bursting cap is arranged on a retaining flange of the main body and surrounds the latter circumferentially.

5. The battery cell closure strip of claim 1, wherein the bursting valve comprises a cutting element which is movably mounted on the main body and by means of which the bursting membrane can be perforated when the nominal internal bursting pressure P.sub.max is reached or exceeded.

6. The battery cell closure strip of claims, wherein the sealing element has a circumferential, sealing lip which, in its sealing position closing the degassing duct, sealingly abuts against a sealing surface of the main body and which can be moved into an open position, in which it opens the degassing duct and in which the sealing lip is arranged at least in portions at a distance from the sealing surface.

7. The battery cell closure strip of claim 1, wherein the sealing element is arranged and retained in a seal-retaining structure of the main body in the form of a recess.

8. The battery cell closure strip of claim 7, wherein the seal retaining structure is formed on an extension of the main body which extends away from the rest of the main body in a direction, which is axial with respect to the vertical axis V of the battery cell closure strip.

9. The battery cell closure strip of claim 7, wherein the recess extends transversely to the vertical axis V of the battery cell closure strip.

10. The battery cell closure strip of claim 1, wherein the battery cell closure strip comprises the terminals of the battery cell or comprises through recesses for the terminals of the battery cell.

11. The battery cell closure strip of claim 1, wherein the battery cell closure strip has a filling opening for the battery cell, which opening can be closed by means of a closure element which is mounted displaceably on the main body.

12. The battery cell closure strip of claim 1, wherein the main body is made of a plastic material, in particular a thermoplastic material, or metal, in particular aluminum.

13. A battery cell of pouch-type design for a traction battery of an electric vehicle, wherein a housing of the battery cell comprises the battery cell closure strip of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the figures:

[0028] FIG. 1 shows a first embodiment of a battery closure strip according to the invention with an integrated degassing duct and an emergency degassing duct in a perspective view;

[0029] FIG. 2 shows an enlarged detail portion of the battery closure strip according to FIG. 1 in the region of the degassing duct with the sealing element removed;

[0030] FIG. 3 shows the battery closure strip according to FIG. 1 in a detail view of the media-operated sealing element of the degassing duct;

[0031] FIG. 4 shows a further embodiment of a battery closure strip in which the bursting valve of the emergency degassing duct and the sealing element of the degassing duct are arranged offset from one another in an axial direction with respect to the vertical axis of the battery closure strip;

[0032] FIG. 5 shows the battery closure strip according to FIG. 4 in a schematic sectional view;

[0033] FIG. 6 shows a further exemplary embodiment of a battery closure strip in which the emergency degassing duct is closed by means of a bursting membrane, the terminals being firmly connected to the main body of the battery cell closure strip;

[0034] FIG. 7 shows a further embodiment of a battery closure strip in which the emergency degassing duct is closed by means of a bursting membrane;

[0035] FIG. 8 shows a prismatic battery cell (without contents) with a battery closure line comprising a cutting piston for pressure-controlled perforation of the bursting membrane, in a sectional view; and

[0036] FIGS. 9a, 9b show a pouch-type battery cell (FIG. 9a) with a battery closure line comprising a degassing duct according to any of the preceding FIGS. 1 to 8 and which is separable/ejectable from the rest of the battery cell housing when reaching/exceeding a bursting pressure P.sub.crit (FIG. 9b).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] FIG. 1 shows a first embodiment of a battery closure strip 10 for a battery cell in prismatic or pouch-type design. Due to their compact, lightweight design, such battery cells are used in particular for traction batteries in electric vehicles, but have the disadvantage of a housing that is not very stable under pressure with respect to gas generation inside the battery cell.

[0038] The battery closure strip 10 has a main body 12 with an inner side 14 and with an outer side 16. in the mounted state, the inner side 14 faces the interior of the housing of the battery cell. The battery closure strip 10 may comprise the terminals 18, i.e. the electrical battery poles of the battery cell, or at least be provided with a through recess 20 for the terminals 18. In the first case, the terminals 18 may be embedded, glued or otherwise sealingly retained in the material of the main body 12.

[0039] The battery closure strip 10 comprises a degassing duct 22 extending along the vertical axis V of the battery closure strip 10 from the inner side 14 to the outer side 16 of the battery closure strip 10. The degassing duct 22 is provided with a valve 24 having a media-operated sealing element 26. During regular operation of the battery cell closure strip 10, the degassing duct 22 is closed in a gas-tight manner by means of the sealing element 26. When a predefined limit pressure P.sub.lim of the battery cell acting on the inside of the sealing element 26 is reached or exceeded, deformation of the sealing element 26 is caused in such a way that the sealing element 26 fluidically opens the degassing duct 22, thus enabling degassing of the battery cell. The response pressure or limit pressure P.sub.lim of the sealing element 26 can be 0.1 bar (above atmospheric pressure), for example.

[0040] In the event of massive gas generation within the battery cell, such as during thermal runaway, no sufficiently rapid atmospheric pressure equalization is possible via the degassing duct 22. The battery cell closure strip 10 therefore additionally comprises an emergency degassing duct 28. In other words, the emergency degassing duct 28 is formed separately from the degassing duct 22 in the main body 12. The emergency degassing duct 28 is closed in a gas-tight manner by means of a bursting valve 30. The bursting valve 30 is designed in such a way that it opens the emergency degassing duct 28 when a bursting pressure P.sub.crit acting on the inside of the bursting valve 30 is reached or exceeded, where P.sub.crit>P.sub.lim. The bursting pressure P.sub.crit can be equal to 1.5 bar, for example. The emergency degassing duct 28 has an opening cross section through which media can flow that is at least 10 times larger than that of the degassing duct 22. According to FIG. 1, the bursting valve 30 can comprise or be formed of a bursting cap 32. The bursting cap 32 is preferably made of plastic material, such as a rubber-elastically deformable material. It should be noted that the main body 12 of the battery cell closure strip 10 has a circumferential connection surface 34, which serves for the gas-tight attachment of the pouch-shaped or prismatic battery cell housing to the battery cell closure strip 10. This can be achieved by welding, gluing, or other means familiar to those skilled in the art.

[0041] In FIG. 2, an enlarged detail portion of the exposed battery cell closure strip 10 is shown in the region of the degassing duct 22. The main body 12 has a seal retaining structure 36 for the sealing element 26 in the form of a recess, which is circular in the present example. The recess is circumferentially bounded by a wall 38. The wall 38 can form a circumferential shoulder 40 that serves as a sealing surface for the sealing element 26.

[0042] In FIG. 3, the sealing element 26 is shown in the mounted state. The sealing element 26 has a sealing lip 42, which is circumferential in the present example, which, in regular operation of the battery cell strip 10, sealingly abuts against the sealing surface in a pretensioned manner in an axial direction with respect to the longitudinal axis L of the recess. The sealing element 26 may have a projection 44, with which it is supported on the main body 12 in an axial direction with respect to the longitudinal axis L. The inner inlet 46 and the outer outlet 48 of the degassing duct 22 can be clearly seen. It should be noted that the longitudinal axis L of the recess is arranged to extend orthogonally with respect to the vertical axis V of the battery cell closure strip 10. As a result, a sufficiently compact design for the presently relevant battery cells can be realized with the battery closure strip 10.

[0043] In FIGS. 4 and 5, another exemplary embodiment of a battery cell closure strip 10 is shown, which differs from the exemplary embodiment explained above in connection with FIGS. 1 to 3 explained above substantially in the geometric position of the sealing element 26 relative to the bursting valve 30. In this case, the seal retaining structure 36 is formed on an extension 50 of the main body 12 that extends away from the rest of the main body 12 in an axial direction with respect to the vertical axis V of the battery cell closure strip 10. Thus, the sealing element 26 and the bursting valve 30 of the emergency degassing duct 28 are spaced apart from each other in the direction of the vertical axis V and are arranged one above the other.

[0044] FIG. 5 shows a battery cell 100 with the battery cell closure strip 10. The battery cell 100 has a (generally) prismatic housing shape. In particular, the battery cell closure strip 10 may be welded to the rest of the housing 102 of the battery cell 100. The bursting cap 32 may be arranged on a retaining flange 52 of the main body 12 and may surround the latter—preferably on both sides—circumferentially.

[0045] FIGS. 6 and 7 each show further battery cell closure strips 10 in which the emergency degassing duct 28 includes a bursting valve 30 having a bursting membrane 53. The bursting membrane may be made of a plastic material, metal or composite material. The bursting membrane offers the advantage of a particularly inexpensive and compact design. The opening cross section A1 of the emergency degassing duct 28 and the significantly smaller opening cross section A2 of the degassing duct 22 can be clearly seen.

[0046] According to the exemplary embodiment shown in FIG. 6, in all embodiments explained herein, the battery cell closure strip 10 can comprise a filling opening 54 for filling the battery cell, which opening can be closed by means of a closure element 56, in particular in the form of a cylindrical plug, which is preferably displaceably mounted on the battery cell closure strip 10. According to the exemplary embodiment shown in FIG. 6, the terminals 18 may be fixedly connected to the main body 12 and form a jointly handled structural unit therewith. Referring to FIG. 7, the seal retaining structure 36 and the sealing element 26 disposed therein may be disposed at the edge of the battery cell closure strip 10.

[0047] If the battery cell closure strip 10 has a bursting membrane 53, then, according to FIG. 8, a pneumatically actuated (=media-operated) cutting element or a media-operated cutting piston 58 can be movably mounted in the emergency degassing duct 28, by means of which the bursting membrane can be mechanically perforated when the battery cell closure strip 10 is in use and when the predefined (=nominal) bursting pressure P.sub.max is reached or exceeded. The cutting piston has a cutting edge 60 associated with the bursting membrane 53. This can further improve the response behavior of the bursting valve 30.

[0048] The main body 12 of the battery cell closure strip 10 above can in principle be made of a plastic material, in particular a thermoplastic material, or metal, in particular aluminum.

[0049] FIG. 9a shows a pouch battery cell 100 with a further battery cell closure strip 10 for a better explanation. The battery cell closure strip 10 may, for example, be embodied according to any of the embodiments according to FIGS. 1 to 8. The pouch-shaped housing 102 is attached to the circumferential connection surface 34 of the main body 12 of the battery cell closure strip 10, in particular welded or bonded thereto. The main body 12 may include a degassing duct and an emergency degassing duct in a manner corresponding to the preceding embodiments.

[0050] In the embodiment shown in this case, however, the battery cell closure strip does not have an integrated emergency degassing duct. Reaching or exceeding the bursting pressure P.sub.crit, where P.sub.crit>P.sub.lim, in the battery cell 100 causes, according to FIG. 9b, a preferably complete separation, in particular ejection, of the battery cell closure strip 10 from the rest of the pouch housing 102 with formation of an emergency degassing duct 28 which, in operation, is open upwards in the direction of the vertical axis V and via which emergency degassing of the battery cell 102 is provided.