Battery cell with directed pressure relief and battery module

Abstract

Battery cell with directed pressure relief, comprising: a housing (100); and a cover plate (200), wherein the cover plate (200) is formed on the housing (100), and the cover plate (200) is provided with an explosion-proof valve, wherein the explosion-proof valve comprises an arc notch (201) and a connecting section (202), wherein the arc notch (201) and the connecting section (202) are connected end-to-end to enclose a circular structure, wherein the circular structure divides the cover plate (200) into a circular section and an annular section, wherein the circular section and the annular section are both connected to the connecting section (202), wherein, when the explosion-proof valve is opened, the arc notch (201) is broken, and the circular section is inverted around the connecting section (202).

Description

This application claims priority to Chinese patent application No. 202221498678.3, filed with the Chinese Patent Office on June 15, 2022. The entire contents of this application are incorporated by reference into this application. Technical area The present application relates to the field of battery technology, for example to a battery cell with directed pressure relief and a battery module. State of the art To prevent the battery cell from exploding in the event of thermal runaway, the battery cell is typically equipped with an explosion-proof valve structure. The explosion-proof valve structure allows heat to be released from the battery cell, preventing the battery cell from exploding and ensuring the user's life safety. Generally, the explosion-proof valve structure in related technologies is usually a cross-notch at the bottom of the battery cell. When thermal runaway occurs in the battery cell, the pressure inside the battery cell increases, and the pressure inside the battery cell is released. However, if the cross-notch is broken, the opening direction of the cross-notch cannot be controlled, and there is a risk that the cover plate sealing the bottom of the battery cell will be released. Due to the pressure pulse of the battery cell, the cover plate may be ejected in any direction after being released, which can easily cause injury and compromise the safety of the battery cell. Disclosure of the utility model The present application provides a directional pressure relief battery cell and a battery module, wherein the explosion-proof valve can be opened directionally, and the connecting portion of the explosion-proof valve can prevent the ejection of the explosion-proof valve, thereby ensuring user safety and good safety performance. In a first aspect, the present application provides a directional pressure relief battery cell comprising: a housing; and a cover plate, wherein the cover plate is formed on the housing, and the cover plate is provided with an explosion-proof valve, the explosion-proof valve comprising an arc notch and a connecting portion, the arc notch and the connecting portion being connected end-to-end to enclose a circular structure, the circular structure separating the cover plate into a circular portion and an annular portion, the circular portion and the annular portion both being connected to the connecting portion, wherein, when the explosion-proof valve is opened, the arc notch is broken, and the circular portion is inverted around the connecting portion. In one embodiment, a side of the annular portion facing the housing is provided with a convex step groove, wherein the step groove is circular and the step groove is coaxial with the cover plate. In one embodiment, a side of the annular portion facing the housing is provided with a plurality of convex arc grooves, wherein the arc grooves are arranged along a circumferential direction of the step groove and a reinforcing rib is formed between two adjacent arc grooves. In one embodiment, the arcuate grooves are evenly distributed along the circumferential direction of the step groove. In one embodiment, an included angle is formed between a bottom wall and a side wall of the reinforcing rib, and the included angle is in the range of 30° to 60°. In one embodiment, a width of the reinforcing rib is in the range of 3mm to 5mm. In one embodiment, the curved groove arranged opposite the connecting section is provided with a positioning rib. In one embodiment, a side of the annular portion facing away from the housing is provided with an annular projecting rib, wherein the annular projecting rib is coaxial with the cover plate. In one embodiment, a length of the connecting portion is smaller than a length of the arc notch and the length of the connecting portion is 5mm to 10mm. In a second aspect, the present application provides a battery module comprising a directional pressure relief battery cell as above, wherein a plurality of directional pressure relief battery cells are provided, wherein the connecting portions of the directional pressure relief battery cells are arranged on the same side of the battery cells. The beneficial effects of this application are:The present application provides a directional pressure relief battery cell comprising: a casing; and a cover plate, wherein the cover plate is formed on the casing, and the cover plate is provided with an explosion-proof valve, the explosion-proof valve including an arc notch and a connecting portion, the arc notch and the connecting portion being connected end-to-end to enclose a circular structure, the circular structure separating the cover plate into a circular portion and an annular portion. When a thermal runaway occurs, the explosion-proof valve is breached, the arc notch is broken, and the circular portion is reversed around the connecting portion, whereby the explosion-proof valve can be opened in a specific direction to release the pressure within the casing.And due to the adjustment of the connecting section, the explosion-proof valve will not be ejected after opening, and the safety performance is better. The present application further provides a battery module comprising the above directional pressure relief battery cell, wherein a plurality of directional pressure relief battery cells are provided, wherein the connecting portions of the directional pressure relief battery cells are arranged on the same side of the battery cells so that the explosion-proof valves of the directional pressure relief battery cells are opened in the same direction when a thermal runaway occurs. Short description of the characters Fig. 1 is a schematic structural diagram of a battery cell with directional pressure relief according to an embodiment of the present application. Fig. 2 is a schematic structural diagram when an explosion-proof valve of a cover plate is not opened according to an embodiment of the present application. Fig. 3 is a schematic structural diagram when an explosion-proof valve of a cover plate is opened according to an embodiment of the present application. Reference symbol 100, housing; 200, cover plate; 201, arcuate notch; 202, connecting portion; 210, step groove; 220, arcuate groove; 2201, reinforcing rib; 2202, positioning rib; 230, annular projecting rib. Detailed embodiments In the description of this application, the terms "connected," "connected," and "fastening" should be understood in the broadest sense, unless expressly stated and limited otherwise. For example, the connection may be fixed, detachable, or one-piece, as well as mechanical and electrical. Furthermore, the connection may be direct, indirect, or established via an intermediate piece, or internally connected between two elements or interacting between two elements. Those of ordinary skill in the art can use the facts of the case to determine the intended meaning of these terms according to the present utility model. In the present application, language that a first feature is "above" or "below" a second feature includes that the first feature is in direct contact with the second feature, or it may include that the first feature is not in direct contact with the second feature, but is in contact with the second feature through additional features between them, unless expressly stated and limited otherwise. Furthermore, language that the first feature is "at," "over," and "on" the second feature includes that the first feature is directly above or diagonally above the second feature, with the first feature being higher in horizontal height than the second feature.And the phrase that the first feature is “below,” “below,” and “inferior” to the second feature implies that the first feature is directly below or diagonally below the second feature, with the first feature being lower in horizontal height than the second feature. In the description of the embodiments, the terms "top," "bottom," "left," "right," "front," "back," etc., are used to refer to the illustrated directional or positional relationship in the respective illustration. They are used solely for convenience of description and to simplify operation, and do not indicate or imply that the device or element in question must have a specific direction, be constructed, and operate in a specific direction. Therefore, they should not be construed as limiting the present application. Furthermore, the terms "first" and "second" are used merely for differentiation in the description and have no particular meaning. As shown in Fig. 1 to Fig. 3, the present application provides a directional pressure relief battery cell. The directional pressure relief battery cell includes a casing 100 and a cover plate 200, wherein the cover plate 200 is formed on the casing 100. One end of the casing 100 is provided with an opening, and an edge of the cover plate 200 is connected to the opening of the casing 100. The cover plate 200 is provided with an explosion-proof valve. The explosion-proof valve includes an arc notch 201 and a connecting portion 202, and the arc notch 201 and the connecting portion 202 are connected end-to-end to enclose a circular structure. The circular structure separates the cover plate 200 into a circular portion and an annular portion, and the circular portion and the annular portion are both connected to the connecting portion 202.When thermal runaway occurs in the battery cell with directional pressure relief, pressure inside the casing 100 increases, and the explosion-proof valve is breached, forming a flow channel to release the pressure inside the casing 100. Since the wall thickness of the arc notch 201 is thinner and the mechanical strength is relatively small compared to other parts, when pressure inside the casing 100 increases, the arc notch 201 is breached first, and the circular portion around the connecting portion 202 is turned outward, thereby realizing directional opening of the explosion-proof valve. Since two ends of the arc notch 201 are not directly connected but are connected by the connecting portion 202, the circular portion cannot be thrown out after being turned around the connecting portion 202, thus ensuring user safety.For example, a side of the circular portion facing an inner side of the housing 100 is provided with a convex stepped groove 210. The stepped groove 210 is circular, and the stepped groove 210 is coaxial with the cover plate 200. High energy density requirements exist for the directional pressure relief battery cell; therefore, the overall thickness of the cover plate 200 is generally thin in related technologies, resulting in a reduction in the pressure resistance of the cover plate 200. When pressure increases inside the housing 100, the cover plate 200 may deform and protrude outward. If the cover plate 200 protrudes from an edge of the housing 100, the heights of the directional pressure relief battery cell are different, which may lead to poor contact or a short circuit. By providing the stepped groove 210, outward bulging of the cover plate 200 can be mitigated.Even if the deformation of the cover plate 200 is slight, normal use of the battery cell with directional pressure relief is not affected. Furthermore, since the stepped groove 210 is recessed toward the inside of the casing 100, a gas storage space within the casing 100 is reduced, the time required to open the explosion-proof valve under thermal runaway conditions is shortened, the sensitivity of the opening of the explosion-proof valve is improved, and the response speed is increased, making the battery cell safer. For example, a side of the circular portion facing the housing 100 is provided with a plurality of convex arc grooves 220. The plurality of arc grooves 220 are arranged along a circumferential direction of the stepped groove 210, and a reinforcing rib 2201 is formed between two adjacent arc grooves 220. By providing the reinforcing rib 2201, the mechanical strength of the cover plate 200 can be improved, and the anti-deformation performance of the cover plate 200 can be improved. For example, the arc grooves 220 are evenly distributed along the circumferential direction of the stepped groove 210, and the arc grooves 220 have the same size and shape. Since the arc groove 220 is also recessed toward the inside of the housing 100, a gas storage space within the housing 100 is reduced, sensitivity upon opening of the explosion-proof valve is improved, and safety performance is improved. The arcuate groove 220 can be formed from sheet metal. To easily demold the arcuate groove 220 during machining, an included angle is defined between a bottom wall and a side wall of the reinforcing rib 2201, and the included angle is in the range of 30° to 60°. For example, in some embodiments, the included angle between the bottom wall and the side wall of the reinforcing rib 2201 can be set to 30°, 40°, 50°, or 60°, which is not repeated here. A width of the reinforcing rib 2201 is set to 3 mm to 5 mm. For example, the width of the reinforcing rib 2201 can be set to 3 mm, 3.5 mm, 4 mm, 4.5 mm, or 5 mm, and other values within the range of 3 mm to 5 mm, although this is not limited in the embodiment. Generally, during the assembly of directional pressure relief battery cells, the directional pressure relief battery cells must be carried or transferred. During this process, since the casing 100 and the cover plate 200 of the directional pressure relief battery cell are both circular, a position of the connecting portion 202 on the cover plate 200 is difficult to determine. If the connecting portion 202 is installed randomly, the opening directions of the explosion-proof valves of a plurality of directional pressure relief battery cells are not uniform. Therefore, a positioning structure is required to determine the installation positions of the directional pressure relief battery cells. In the embodiment, four arc grooves 220 are taken as an example for illustration. Four reinforcing ribs 2201 are also formed between the corresponding four arc grooves 220. An included angle between the center lines of two adjacent ones of the four reinforcing ribs 2201 is 90°. The connecting portion 202 and a center of two of the four arc grooves 220 are located on the same straight line. The arc groove 220 located opposite the connecting portion 202 is provided with a positioning rib 2202. In a transfer device for supporting the battery cell with directional pressure relief, a clamping groove is arranged at a position corresponding to the positioning rib 2202.The positioning rib 2202 can be clamped in the clamping groove, thereby determining an installation position of the directional pressure relief battery cell, ensuring that the connecting portions 202 on the cover plates 200 of a plurality of directional pressure relief battery cells are on the same side, and that the opening directions of explosion-proof valves of a plurality of directional pressure relief battery cells are the same. In some embodiments, the cover plate 200 and the housing 100 may be secured in a grooved seal. In this case, due to the sealing process, when the circular structure of the cover plate 200 is subjected to internal pressure, a compressive stress on the annular portion is greater than a compressive stress on the circular portion. Therefore, to ensure sufficient sealing strength of the cover plate 200, with further reference to FIGS. 2 and 3, a side of the annular portion of the cover plate 200 facing away from the housing 100 is provided with an annular protruding rib 230, and the annular protruding rib 230 is coaxial with the cover plate 200, thereby improving the compressive stress performance of the cover plate 200 and ensuring good sealing performance. In the embodiment, an outer diameter of the cover plate 200 is 44 mm, an outer diameter of the housing 100 is 46 mm, and a length of the connecting portion 202 is smaller than a length of the arc notch 201. The length of the connecting portion 202 ranges from 5 mm to 10 mm. A minimum diameter of the step groove 210 is 6 mm, and a maximum diameter of the step groove 210 is 17 mm. An inner diameter of the annular protruding rib 230 is 36 mm, and an outer diameter of the annular protruding rib 230 is 42 mm. In other embodiments, the above structures can also be set to other sizes, which are not limited by the embodiment. The embodiment of the present application further provides a battery module. The battery module includes the above directional pressure relief battery cell. A plurality of directional pressure relief battery cells are provided in the battery module. The connecting portions 202 of the directional pressure relief battery cells are arranged on the same side of the battery cells, so that the explosion-proof valves of the directional pressure relief battery cells can be opened in the same direction to release pressure within the casing 100 when a thermal runaway occurs. In addition, by providing the connecting portion 202, the explosion-proof valve cannot be ejected after opening, thus increasing safety. QUOTES CONTAINED IN THE DESCRIPTION This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature CN 202221498678.3

[0001]

Claims

A battery cell with directional pressure relief, comprising: a housing (100); and a cover plate (200), wherein the cover plate (200) is formed on the housing (100), and the cover plate (200) is provided with an explosion-proof valve, wherein the explosion-proof valve comprises an arc notch (201) and a connecting portion (202), wherein the arc notch (201) and the connecting portion (202) are connected end-to-end to enclose a circular structure, wherein the circular structure separates the cover plate (200) into a circular portion and an annular portion, wherein the circular portion and the annular portion are both connected to the connecting portion (202), wherein, when the explosion-proof valve is opened, the arc notch (201) is broken, and the circular portion is inverted around the connecting portion (202). A battery cell with directional pressure relief according to claim 1, wherein a side of the annular portion facing the housing (100) is provided with a convex step groove (210), the step groove (210) being circular and the step groove (210) being coaxial with the cover plate (200). A battery cell with directional pressure relief according to claim 2, wherein a side of the annular portion facing the housing (100) is provided with a plurality of convex arc grooves (220), the arc grooves (220) being arranged along a circumferential direction of the step groove (210), and a reinforcing rib (2201) being formed between two adjacent arc grooves (220). A battery cell with directional pressure relief according to claim 3, wherein the arc grooves (220) are evenly distributed along the circumferential direction of the step groove (210). A battery cell with directional pressure relief according to claim 3 or 4, wherein an included angle is formed between a bottom wall and a side wall of the reinforcing rib (2201), and the included angle is in the range of 120° to 150°. A battery cell with directional pressure relief according to any one of claims 3 to 5, wherein a width of the reinforcing rib (2201) is in the range of 3mm to 5mm. Battery cell with directional pressure relief according to one of claims 3 to 6, wherein the arcuate groove (220) arranged opposite the connecting portion (202) is provided with a positioning rib (2202). A battery cell with directional pressure relief according to any one of claims 1 to 7, wherein a side of the annular portion facing away from the housing (100) is provided with an annular projecting rib (230), the annular projecting rib (230) being coaxial with the cover plate (200). A battery cell with directional pressure relief according to any one of claims 1 to 8, wherein a length of the connecting portion (202) is smaller than a length of the arc notch (201) and the length of the connecting portion (202) is 5mm to 10mm. A battery module comprising a directional pressure relief battery cell according to any one of claims 1 to 9, wherein a plurality of directional pressure relief battery cells are provided, wherein the connecting portions (202) of the directional pressure relief battery cells are arranged on the same side of the battery cells so that the explosion-proof valves of the directional pressure relief battery cells are opened in the same direction.

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