Optimised dimensioning of a burst membrane for battery cells

Abstract

The invention relates to a membrane arrangement for a battery cell, the membrane arrangement comprising a cell housing having a prismatic shape and a burst membrane, the cell housing having at least two side surfaces and at least two narrow sides, the cell housing having a length, a width, and a height, and the burst membrane having a membrane length and a membrane width, wherein the burst membrane is positioned in or on a narrow side of the cell housing, wherein the burst membrane has a membrane length which corresponds to 0.25 times to 0.4 times the length of the cell housing, and wherein the burst membrane has a membrane width which corresponds to 0.44 times to 0.6 times the width of the cell housing. The invention also relates to a battery cell.

Description

[0001] OPTIMIZED DIMENSIONING OF A BURST MEMBRANE FOR BATTERY CELLS

[0002] The invention relates to a membrane arrangement for a battery cell, comprising a cell housing with a prismatic shape and a rupture membrane, wherein the cell housing has at least two side faces and at least two narrow sides, wherein the cell housing has a length, a width, and a height, and wherein the rupture membrane has a membrane length and a membrane width. The invention further relates to a battery cell.

[0003] Electrochemical storage devices, such as lithium-ion batteries, can release gaseous components under certain critical conditions, thereby building up overpressure within the cell casing of one or more battery cells. Such critical conditions can occur, for example, due to overload or a defect in the battery cell. Excessive pressure within the cell casing of a battery cell can result in an explosion risk. Battery cells with integrated predetermined breaking points are already known; these are designed to rupture and release the overpressure at a predefined level. For example, predetermined breaking points can be incorporated into the walls of battery cell casings in the form of punches or embossing to prevent hazardous overpressure.

[0004] Furthermore, rupture membranes are already known that are connected externally to a cell lid of the battery cell casing. However, a problem with externally connecting rupture membranes, especially by welding, is the need for a certain material thickness of both the rupture membrane and, for example, the cell lid, to ensure a reliable connection between the rupture membrane and the corresponding section of the battery cell. Increasing the material thickness of cell casings and cell lids to enable a reliable connection of the rupture membrane, however, conflicts with minimizing weight and increasing the energy density of the battery cells. For this reason, rupture membranes are predominantly integrated into cell lids with sufficient material thickness to circumvent this problem. The cell lid typically forms the highest point of the battery cell and also incorporates electrical connections.Depending on the arrangement and orientation of the cell stacks, however, the gases produced may be insufficiently or not completely vented through the cell lid. Furthermore, the electrical connections can impede the formation of a gas channel for venting gases from the battery cells. In particular, due to the electrical connections, a rupture membrane integrated into a cell lid can only be gas-tightly coupled to external channels with considerable effort to enable the controlled venting of gaseous components from a battery system or a battery module housing containing a large number of battery cells.

[0005] In addition to the position of the rupture membrane, its adequate size is also essential. A rupture membrane with an insufficient cross-sectional area can restrict the velocity of the gases escaping from the cell casing and delay pressure release. Conversely, a rupture membrane with an excessively large cross-sectional area allows for rapid pressure release but can compromise the mechanical stability of the cell casing.

[0006] The present invention therefore aims to provide a membrane arrangement for a battery cell and a battery cell which enables optimal dimensioning of the rupture membrane. This objective is achieved by the features specified in claim 1. Further advantageous embodiments of the invention are part of the dependent claims.

[0007] According to one aspect of the invention, a membrane arrangement for a battery cell is provided. The membrane arrangement comprises a cell housing with a prismatic shape and a rupture membrane. The cell housing has at least two side surfaces and at least two narrow sides. The side surfaces may have a larger area than the narrow sides.

[0008] The cell casing has a length, a width, and a height. The rupture membrane has a length and a width. The rupture membrane is positioned in or on a narrow side of the cell casing.

[0009] According to the invention, the rupture membrane has a membrane length corresponding to 0.25 to 0.4 times the length of the cell casing. Furthermore, the rupture membrane has a membrane width corresponding to 0.45 to 0.6 times the width of the cell casing.

[0010] The dimensioning of the rupture membrane depending on the dimensions of the battery cell housing enables a maximization of the possible cross-section or cross-sectional area and the mechanical stability of the cell housing.

[0011] For example, by using a membrane width of 0.44 to 0.6 times the width of the cell casing, sufficient circumferential space can be created for any seals or welds between the rupture membrane and the section of the cell casing.

[0012] Limiting the membrane length to 0.25 to 0.4 times the length of the cell casing can optimize the stability of the cell casing.

[0013] In an advantageous embodiment of the membrane arrangement, the cross-sectional area of ​​the rupture membrane relative to the cross-sectional area of ​​its narrow side can be used to dimension the membrane, instead of its length and width. For this purpose, the cross-sectional area of ​​the rupture membrane can, for example, be in the range of 0.1125 to 0.24 times the cross-sectional area of ​​its narrow side. Here, the narrow side corresponds to the side of the cell casing on which the rupture membrane is positioned.

[0014] According to a further aspect of the invention, a battery cell with a membrane arrangement according to the invention is provided. The cell housing of the battery cell is fluid-tightly sealed by at least one cell cover. At least one electrode pack is arranged in an inner volume of the cell housing.

[0015] The electrode assembly can, for example, comprise anode electrodes, cathode electrodes, and separators, which are electrically connected to the battery terminals via appropriate conductors. The anode electrodes, cathode electrodes, and separators can, for example, be stacked or wound in foil form to form electrode assemblies. One or more such electrode assemblies can be arranged within the internal volume of the cell casing. Furthermore, an electrolyte or an electrolyte solution can be provided within the internal volume of the cell casing.

[0016] The cell casing has a prismatic shape. In particular, the prismatic shape of the cell casing can have any polygonal base.

[0017] For example, the base can be rectangular, square, or similar. The base shape can form one narrow side of the cell casing. At least two lateral surfaces of the prismatic shape can serve as the sides of the cell casing.

[0018] In one embodiment, the rupture membrane is inserted into an opening in the cell housing, or, in an alternative or additional embodiment, it covers an opening in the cell housing. This allows for flexible attachment of the rupture membrane to the cell housing. Various methods, such as welding, pressing, and the like, can be used to connect the rupture membrane to the cell housing. In one embodiment, the length and width of the rupture membrane essentially correspond to the length and width of the opening. This allows the dimensions of the opening, as the maximum permissible flow cross-section of the rupture membrane, to be determined independently of the geometry or design of the rupture membrane. This measure allows for subsequent adjustment or modification of the rupture membrane while keeping the battery cell components unchanged.

[0019] The rupture membrane can be arranged behind the opening, on the opening, above the opening, partially overlapping or covering the opening, projecting into the opening, inside the opening, for example pressed into the opening, and so on.

[0020] The rupture membrane can be arranged internally, i.e., within the inner volume of the battery cell housing, and / or externally, i.e., outside the inner volume of the cell housing, on at least one outer wall.

[0021] The rupture diaphragm can be set with particular precision to a limiting overpressure if it has at least one perforation in the form of a predetermined breaking point. This perforation is designed to break upon activation of the rupture diaphragm, exposing a cross-section.

[0022] According to another embodiment, the membrane length and width correspond to the length and width of the exposed cross-section. This allows a relevant cross-sectional area of ​​the rupture membrane to be defined even when it is integrated into and / or embossed in a cell housing wall.

[0023] The rupture membrane can be connected to an external discharge channel in a particularly efficient manner if at least one perforation is incorporated into at least one narrow side of the cell housing. According to a further embodiment, the cell housing has a width and a length with a relative ratio to each other within a range of 0.05 to 0.15, including 0.05 and 0.15. According to another embodiment, the cell housing has a width and a height with a relative ratio within a range of 0.18 to 0.3, including 0.18 and 0.3. These measures allow for the provision of a cell housing with dimensions, particularly in the form of relative ratios between the height, width, and length of the cell housing, which is mechanically robust and technically easy to manufacture.

[0024] Several embodiments of the invention are explained in more detail below with reference to the drawings. The drawings show:

[0025] Fig. 1 shows a perspective view of a membrane arrangement according to an embodiment of the invention,

[0026] Fig. 2 shows a sectional view of a bottom section of a battery cell with a membrane arrangement from Fig. 1, and

[0027] Fig. 3 shows a sectional view of a bottom section of a battery cell with a membrane arrangement according to a further embodiment of the invention.

[0028] In the illustrations, identical reference numerals denote the same elements or structural components. The sizes and relative positions of the elements in the illustrations are not necessarily drawn to scale, and some of these elements are shown enlarged and repositioned for clarity. Furthermore, the specific shapes of the drawn elements are not intended to convey information about the actual shape of the individual elements but were chosen solely for easier identification in the illustrations. Fig. 1 shows a perspective view of a membrane arrangement 10 according to an embodiment of the invention. The membrane arrangement 10 is advantageously configured for use in battery cells 100, which are shown by way of example in Fig. 2.

[0029] The membrane assembly 10 has a cell housing 20 with a prismatic shape and is, by way of example, made of an aluminum alloy. In the illustrated embodiment, the cell housing 20 has a rectangular prism shape and is open on two opposite sides S1, S2 by openings 21, 22.

[0030] This allows components of the battery cell 100 to be placed into an internal volume V of the cell housing 20.

[0031] The cell housing 20 has two opposing narrow sides 23 and two larger side surfaces 24. The cell housing 20 has a length L, a width B, and a height H. In the illustrated embodiment, the narrow sides 23 are defined by the width B and the length L. The side surfaces 24 are defined by the height H and the length L.

[0032] An exemplary bottom-side narrow end 23 of the cell housing 20 is provided with an opening 31, which is closed by a rupture membrane 30. The rupture membrane 30 rests, for example, in the form of a plate on the inside of the opening 31. Depending on the embodiment, the rupture membrane 30 can be welded, glued, tilted, or soldered to the wall of the narrow end 23. A rupture membrane 30 inserted into or arranged on the opening 31 of the cell housing 20 in this manner has a membrane length I and a membrane width s, which essentially correspond to the length and width of the opening 31 itself. Preferably, the opening 31, and thus also the rupture membrane 30, is centered along the width B and decentered or laterally offset along the length L.

[0033] The rupture membrane 30 has a membrane length I, which corresponds to 0.25 to 0.4 times the length L of the cell casing 20. Furthermore, the rupture membrane 30 has a membrane width s, which corresponds to 0.45 to 0.6 times the width B of the cell casing 20.

[0034] A burst membrane 30 can therefore be designed or dimensioned particularly advantageously based on the two following relationships.

[0035] 0.44 < s / B < 0.6 0.25 < l / L < 0.4

[0036] For an exemplary cell housing 20 with a length L of 270 mm, a width B of 25 mm, and a height H of 100 mm, the rupture membrane 30 can have a membrane width s of 11 mm to 15 mm and a membrane length I of 67.5 mm to 108 mm. Within this range, which also includes the limits of the range, a particularly optimal compromise can be achieved between the stability of the cell housing 20 and the fastest possible pressure reduction in the event of the rupture membrane 30 being triggered.

[0037] For optimal formation of the cell casing 20, it can also be dimensioned using the following ratios:

[0038] 0.05 < W / L < 0.15 0.18 < W / H < 0.3

[0039] A corresponding cell housing 20 can therefore have a width-to-length ratio B / L of, for example, 20 / 250, 30 / 300, 25 / 167, and the like. Accordingly, with a width B of 25 mm, a height H of the cell housing 20 can be selected in a range from 85 mm to 140 mm, including 85 mm and 140 mm.

[0040] Figure 2 shows a sectional view of a bottom section of a battery cell 100 with a membrane arrangement 10 from Figure 1. Figure 2 illustrates the design of the rupture membrane 30 in the form of a plate, which is arranged at the opening 31 of the cell housing 20.

[0041] The rupture membrane 30 can generally have any design. The rupture membrane 30 has at least one perforation 32 in the form of a predetermined breaking point. The perforation 32 is designed to break when the rupture membrane 30 is triggered, thus exposing a cross-section. In the embodiment shown in Fig. 2, this cross-section can be limited by the dimensions of the opening 31.

[0042] The battery cell 100 has cell covers (not shown) which close the openings 21, 22 at their ends. At least one electrode pack 110 is positioned in the internal volume V of the cell housing 20. An electrolyte or an electrolyte solution can also be provided in the internal volume V of the cell housing 20.

[0043] Fig. 3 shows another sectional view of a bottom section of a battery cell 100 with a membrane arrangement 30 according to a further embodiment of the invention. In contrast to the embodiment shown in Fig. 2, the rupture membrane 30 is embossed or punched into the bottom narrow side 23. Thus, the exemplary perforation 32 is formed directly in the wall of the narrow side 23.

[0044] To limit the cross-section of the rupture membrane 30 in the event of triggering by overpressure in the internal volume V of the cell housing 20, secondary perforations 33 are provided, which define, for example, the membrane width s and the membrane length I. The rupture membrane 30 can have a design determined by the shape, extent, and number of perforations 30, 33. For example, the perforations 30, 33 can be shaped as a double Y, touching circles or semicircles, one or more intersecting or parallel lines, and the like. Using the relationships described above, the rupture membrane 30 can be dimensioned relative to the planned dimensions of the cell housing 20, regardless of its design.

[0045] EXECUTION FORMS

[0046] 1. Membrane arrangement (10) for a battery cell (100), comprising a cell housing (20) with a prismatic shape and a rupture membrane (30), wherein the cell housing (20) has at least two side faces (24) and at least two narrow sides (23), wherein the cell housing (20) has a length (L), a width (B) and a height (H), and wherein the rupture membrane (30) has a membrane length (I) and a membrane width (s), wherein the rupture membrane (30) is positioned in or on a narrow side (23) of the cell housing (20), characterized in that the rupture membrane (30) has a membrane length (I) corresponding to 0.25 to 0.4 times the length (L) of the cell housing (20) and that the rupture membrane (30) has a membrane width (s) corresponding to 0.44 to 0.6 times the width (B) of the cell housing (20). cell casing (20) corresponds.

[0047] 2. Membrane arrangement according to embodiment I, wherein the rupture membrane (30) is inserted into an opening (31) of the cell housing (20) or covers an opening (21) of the cell housing (20), wherein the membrane length (I) and membrane width (s) of the rupture membrane (30) substantially correspond to the length and width of the opening (31). Membrane arrangement according to embodiment I or 2, wherein the rupture membrane (30) has at least one perforation (32, 33) in the form of a predetermined breaking point, wherein the at least one perforation (32, 33) is configured to break upon activation of the rupture membrane (30) and expose a cross-section. Membrane arrangement according to embodiment I, wherein the membrane length (I) and the membrane width (s) correspond to the length and width of a cross-section exposed upon activation of the rupture membrane (30).Membrane arrangement according to embodiment 4, wherein the at least one perforation (32) is provided in at least one narrow side (23) of the cell housing (20). Membrane arrangement according to any one of embodiments 1 to 5, wherein the cell housing (20) has a width (B) and a length (L) with a relative ratio to each other within a range of 0.05 to 0.15, including 0.05 and 0.15. Membrane arrangement according to any one of embodiments 1 to 6, wherein the cell housing (20) has a width (B) and a height (H) with a relative ratio within a range of 0.18 to 0.3, including 0.18 and 0.3. Battery cell (100) comprising a membrane arrangement (10) according to one of the preceding claims, wherein a cell housing (20) of the membrane arrangement (10) is fluid-tightly sealed by at least one cell cover, wherein at least one electrode pack (110) is arranged in an internal volume (V) of the cell housing (20).

Claims

REQUIREMENTS 1. Membrane arrangement (10) for a battery cell (100), comprising a cell housing (20) with a prismatic shape and a rupture membrane (30), wherein the cell housing (20) has at least two side faces (24) and at least two narrow sides (23), wherein the cell housing (20) has a length (L), a width (B) and a height (H), and wherein the rupture membrane (30) has a membrane length (I) and a membrane width (s), wherein the rupture membrane (30) is positioned in or on a narrow side (23) of the cell housing (20), characterized in that the rupture membrane (30) has a membrane length (I) corresponding to 0.25 to 0.4 times the length (L) of the cell housing (20) and that the rupture membrane (30) has a membrane width (s) corresponding to 0.44 to 0.6 times the width (B) of the cell housing (20). cell casing (20) corresponds to the burst membrane (30) in an opening (31) of the cell casing (20) or covers an opening (21) of the cell casing (20), wherein the membrane length (I) and membrane width (s) of the bursting membrane (30) substantially corresponds to the length and width of the opening (31), and wherein the bursting membrane (30) has at least one perforation (32, 33) in the form of a predetermined breaking point, wherein the at least one perforation (32, 33) is designed to break upon triggering of the bursting membrane (30) and to expose a cross-section.

2. Membrane arrangement according to claim 1, wherein the membrane length (I) and the membrane width (s) correspond to a length and a width of a cross-section exposed upon activation of the burst membrane (30).

3. Membrane arrangement according to claim 1, wherein the at least one perforation (32) is inserted into at least one narrow side (23) of the cell casing (20).

4. Membrane arrangement according to any one of claims 1 to 3, wherein the cell housing (20) has a width (B) and a length (L) with a relative ratio to each other within a range of 0.05 to 0.15, including 0.05 and 0.

15.

5. Membrane arrangement according to any one of claims 1 to 4, wherein the cell housing (20) has a width (B) and a height (H) with a relative ratio within a range of 0.18 to 0.3, including 0.18 and 0.

3.

6. Battery cell (100) comprising a membrane arrangement (10) according to one of the preceding claims, wherein a cell housing (20) of the membrane arrangement (10) is fluid-tightly sealed by at least one cell cover, wherein at least one electrode pack (110) is arranged in an internal volume (V) of the cell housing (20).

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