Battery cell

Abstract

Battery cell (11), in particular a lithium-ion battery cell, comprising a housing wall (13) and a means (14) for protection against overpressure, which is arranged on the housing wall (13) and has a first, a second and a third groove (15, 16, 17), wherein the first and the second groove (15, 16) are arranged next to one another on the same side of the housing wall (13), characterized in that the third groove (17) lies between the first and second grooves (15, 16) and is arranged on a side of the housing wall (13) opposite the first and second grooves (15, 16), wherein the third groove (17) is arranged on the inner side (21) of the housing wall (13).

Description

State of the art

[0001] The invention is based on a battery cell according to the preamble of the independent claim.

[0002] Various types of batteries are known from the prior art. One such battery is shown, for example, in US 2007 013 45 47 A1. A battery (or a battery system), as used in hybrid or electric vehicles, for example, usually consists of several battery modules, which in turn are made up of individual battery cells (e.g. lithium-ion battery cells). An individual battery cell has a housing and electrical storage elements (also referred to as galvanic cells or, more simply, as cells) arranged in the housing. Batteries are subject to predetermined restrictions, which affect, for example, the maximum possible housing dimensions. On the one hand, these are specified by industry standards, and on the other hand, they are limited by the installation space available for battery cells or modules.The limited battery cell volume is partially filled by the storage elements (electrochemically active materials and electrolytes) and partially by inert components (current collectors, seals, separators, etc.). An unfilled residual volume usually remains, which is necessary to absorb reaction products or to compensate for other effects such as material expansion due to high temperatures. Electrochemical cells can generate gas during both charging and discharging. Gas evolution can occur particularly under unusual conditions, such as accidental deep discharge or during the initial charging of a primary cell. Accordingly, cells are designed to allow internal excess pressure to escape from the cell in a controlled manner.

[0003] For example, from the aforementioned US 2007 013 45 47 A1 a battery is known in which a pressure relief valve ensures the controlled escape of gas. For this purpose, an annular groove is provided in the housing wall, which is interrupted at least two places. If excess pressure builds up within the battery, the housing wall ruptures preferentially in the area of ​​the groove, where the housing wall is thinner. However, a disadvantage of this device is that the predetermined bursting pressure at which the groove ruptures varies within a wide range around the preferred bursting pressure. Another disadvantage is that the pressure relief valve is incorporated in thin membranes. These must be subsequently welded or clamped into openings in the housing wall, which results in increased labor and cost. In addition, with this type of membrane there is always the risk of a leak between the membrane and the housing.

[0004] JP 2010282851A shows a sealed battery with a safety valve. The safety valve is integrated into the battery housing and designed as a tapered section of the housing wall, surrounded by a slot designed to interrupt heat transfer. The housing wall for the safety valve is tapered from the outside. The slot surrounding the safety valve extends from the inside of the housing into the housing.

[0005] It is the object of the invention to provide a battery cell having an improved pressure relief valve. Advantages of the invention

[0006] The battery cell according to the invention with the characterizing part of claim 1 has the advantage that it has an improved pressure relief valve which opens at a defined bursting pressure, allowing excess pressure to escape from the battery.

[0007] For this purpose, the invention provides that the housing has a pressure relief valve as a means of protection against overpressure, which pressure relief valve is arranged on the housing wall. The pressure relief valve has a first, a second and a third groove, wherein the first and the second groove are arranged next to one another on the same side of the housing wall. The third groove lies between the first and second grooves and on a side of the housing wall opposite the first and second grooves. The third groove is arranged on the inside of the housing wall. If the housing bulges outwards in the area of ​​the grooves due to increased internal pressure, the three grooves act together like a hinge, enabling a controlled opening of the housing. The third groove therefore advantageously makes it easier to break open the housing.This arrangement of the grooves allows the bursting pressure, i.e. the pressure at which the housing breaks open in the area of ​​the grooves, to be precisely adjusted.

[0008] The measures mentioned in the dependent claims enable advantageous further developments of the device specified in the independent claim.

[0009] Advantageously, the first groove and the second groove are arranged at a distance A_1 of 5 to 20 mm from each other. If the distance A_1 between the two grooves is less than 5 mm or greater than 20 mm, the burst pressure can no longer be specified within the desired accuracy.

[0010] Furthermore, it has proven particularly advantageous for setting the bursting pressure that the first groove and / or the second groove have a length L_1 in the range of 10 to 40 mm and / or the third groove has a length in the range of 5 to 30 mm.

[0011] In addition, it has been found to be advantageous that at least one of the three grooves has a depth T_1 in the range of 0.2 to 0.5 mm and / or the first and / or the second and / or the third groove each has a width B_1 in the range of 0.3 to 0.6 mm.

[0012] It is particularly advantageous to position the third groove centrally between the first and second grooves. In this position, the hinge effect can be particularly effective and the burst pressure can be adjusted with greater precision.

[0013] Advantageously, the first and second grooves are connected at at least one end by a further groove to form a circumferential groove. Due to the circumferential groove design, the opening area is advantageously enlarged.

[0014] An elliptical embodiment of the circumferential groove has proven to be particularly advantageous, wherein the circumferential groove has a length L_2 in the range of 10 to 40 mm and / or a width B_2 in the range of 5 to 20 mm.

[0015] It is also advantageous to position the third groove in the area enclosed by the circumferential groove. The central positioning of the third groove allows the hinge-like effect between the first two grooves and the third groove to be optimally developed, allowing the desired burst pressure to be optimally adjusted. drawing

[0016] The invention is explained in more detail below in several embodiments with reference to the accompanying drawings. Fig. 1 shows a perspective view of a battery cell of a first embodiment. Fig. 2 shows a section of the housing wall of the first embodiment. Fig. 3 shows a sectional view of the housing wall of a battery cell. Fig. 4 shows another sectional view of the housing wall of a battery cell. Fig. 5 shows another section of the housing wall of a battery cell. Fig. 6 shows another section of the housing wall of a battery cell. Embodiments of the invention

[0017] Fig. 1 shows a perspective view of a battery cell 11 as a first exemplary embodiment of the invention. The battery cell 11 is essentially rectangular and flat and has a small thickness. At least one electrical storage element (not shown here) is located in the housing 12 of the battery cell 11, which is designed in particular as a lithium-ion storage cell with a flat design without an inherently rigid casing (“jelly rolls” or “coffee bag”). The means 14 for protection against excess pressure (pressure relief valve) is located on the housing wall 13. The pressure relief valve 14 is composed of a first groove 15, a second groove 16, and a third groove 17, wherein the first two grooves 15, 16 are arranged on the outer side 20 of the housing wall 13, whereas the third groove 17 is arranged on the inner side 21 (not shown here) of the housing wall 13.In the direction of view from the first plane 27, in which the first and second grooves 15, 16 are arranged, to the second plane 28 (not shown here), in which the third groove 17 lies, the third groove 17 is arranged centrally between the first and second grooves 15, 16. As a further embodiment of the invention (not shown here), the first and second grooves 15, 16 can also be arranged on the inner side 21 of the housing wall, wherein the third groove 17 lies between the first and second grooves 15, 16 and is arranged on the opposite side of the housing wall 13, the outer side 20.

[0018] Fig. 2 shows a plan view of a section of the housing wall 13 of the battery cell 11 according to the first embodiment of the invention from Fig. 1. The first groove 15 and the second groove 16 are arranged at a distance A_1 of 5 to 20 mm and preferably 12 mm from each other, wherein the first groove 15 and / or the second groove 16 have a length L_1 in the range of 10 to 40 mm and preferably 25 mm. The third groove 17 has a length L_2 in the range of 5 to 30 mm and preferably 20 mm and is located centrally between the first and second grooves 15, 16 and on the side of the housing wall 13 opposite the first and second grooves.

[0019] Fig. 3 shows a sectional view of the housing wall 13 of the battery cell 11 according to the first embodiment of the invention from Fig. 1. The first and / or the second and / or the third groove 15, 16, 17 have a depth T_1 in the range of 0.2 to 0.5 mm and preferably 0.4 mm.

[0020] Fig. 4 shows a further sectional view of the housing wall 13 of the battery cell 11 according to the first embodiment of the invention from Fig. 1, wherein the first and / or the second and / or the third groove 15, 16, 17 have a width B_1 in the range of 0.3 to 0.6 mm and preferably 0.4 mm.

[0021] Fig. 5 shows, as a further embodiment of the invention, a further section of the housing wall 13 of the battery cell 11 from Fig. 1. The first groove 15 is connected to the second groove 16 at one end by a further fourth groove 19 to form a circumferential groove 18. The circumferential groove 18 is open on one side and U-shaped. The area 22 enclosed by the circumferential groove 18 has a length L_1 in the range of 10 to 40 mm, and the legs of the U-shaped circumferential groove 18 are arranged at a distance A_1 of 5 to 20 mm from one another. The third groove 17 is arranged centrally in the area 22 enclosed by the circumferential groove 18 and has a length L_2 in the range of 5 to 30 mm.

[0022] All grooves 15, 16, 17, 18, 19 have a depth T_1 in the range of 0.2 to 0.5 mm and a width B_1 in the range of 0.3 to 0.6 mm. The circumferential groove 18 can be arranged on both the inner side 21 and the outer side 20 of the housing wall 13.

[0023] Fig. 6 shows, as a further embodiment of the invention, a further section of the housing wall 13 of the battery cell 11 from Fig.1. The first groove 15 is connected to the second groove 16 at both ends by further grooves 19, 23 to form a circumferential groove 18. The circumferential groove 18 is closed and elliptical. The circumferential groove 18 forms an ellipse 24 with a large diameter L_1 in the range of 10 to 40 mm and a small diameter A_1 of 5 to 20 mm. The third groove 17 is arranged centrally in the area 24 enclosed by the circumferential groove 19, thus lying on the connecting line of the two focal points 25, 26 of the ellipse formed by the circumferential groove 18 and has a length L_2 in the range of 5 to 30 mm. All grooves 15, 16, 17, 18, 19 have a depth T_1 in the range of 0.2 to 0.5 mm and a width B_1 in the range of 0.3 to 0.6 mm. The circumferential groove 18 can be arranged on both the inner side 21 and the outer side 20 of the housing wall 13.

Claims

[1] Battery cell (11), in particular a lithium-ion battery cell, comprising a housing wall (13) and a means (14) for protection against overpressure, which is arranged on the housing wall (13) and which has a first, a second and a third groove (15, 16, 17), wherein the first and the second groove (15, 16) are arranged next to each other on the same side of the housing wall (13), characterized by , that the third groove (17) is located between the first and second grooves (15, 16) and is arranged on a side of the housing wall (13) opposite the first and second grooves (15, 16), wherein the third groove (17) is arranged on the inside (21) of the housing wall (13). [2] Battery cell (11) according to claim 1, characterized by , that the first groove (15) and the second groove (16) are arranged at a distance A_1 of 5 to 20 mm from each other. [3] Battery cell (11) according to any of the preceding claims, characterized by, that the first groove (15) and / or the second groove (16) have a length L_1 in the range of 10 to 40 mm. [4] Battery cell (11) according to any of the preceding claims, characterized by , that the third groove (17) has a length L_2 in the range of 5 to 30 mm. [5] Battery cell (11) according to any of the preceding claims, characterized by , that at least one of the three grooves (15, 16, 17) has a depth T_1 in the range of 0.2 to 0.5 mm. [6] Battery cell (11) according to any of the preceding claims, characterized by , that the first and / or the second and / or third groove (15, 16, 17) each have a width B_1 in the range of 0.3 to 0.6 mm. [7] Battery cell (11) according to any of the preceding claims, characterized by , that the third groove (17) is located midway between the first groove (15) and the second groove (16). [8] Battery cell (11) according to any of the preceding claims, characterized by, that the first and second grooves (15, 16) are connected at at least one end by a fourth groove (19) to form a circumferential groove (18). [9] Battery cell (11) according to any of the preceding claims, characterized by , that the circumferential groove (18) is elliptical. [10] Battery cell (11) according to any of the preceding claims, characterized by , that the circumferential groove (18) has a length L_2 in the range of 10 to 40 mm. [11] Battery cell (11) according to any of the preceding claims, characterized by , that the circumferential groove (18) has a width B_2 in the range of 5 to 20 mm. [12] Battery cell (11) according to any of the preceding claims, characterized by , that the third groove (17) is encompassed by the area (24) enclosed by the circumferential groove (18).

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