Battery cells, batteries and electrical devices

Abstract

The present application provides a battery cell, a battery and an electrical device. The battery cell includes a shell and an explosion-proof valve sheet, the shell includes a shell wall, and the shell wall has an exhaust channel that penetrates in the wall thickness direction. The explosion-proof valve sheet is arranged on the shell wall and is used to cover the exhaust channel. The explosion-proof valve sheet includes a reversing groove and a cracking groove. The groove depth of the reversing groove is less than the groove depth of the cracking groove. The cracking groove is configured to rupture under the action of the air pressure in the shell so that part of the explosion-proof valve sheet is turned outward around the reversing groove relative to the shell wall to open the exhaust channel. The explosion-proof valve sheet includes a stamping area. The thickness of the stamping area is less than the thickness of the unstamped area of ​​the explosion-proof valve sheet. The reversing groove and the cracking groove are provided in the stamping area. The difference between the first residual thickness of the explosion-proof valve sheet at the reversing groove and the second residual thickness of the explosion-proof valve sheet at the cracking groove is less than the difference between the thickness of the stamping area and the second residual thickness of the explosion-proof valve sheet. The technical solution of the present application avoids explosion by arranging a cracking groove on the explosion-proof valve sheet.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and more particularly to a battery cell, a battery and an electrical device. Background Art

[0002] With the continuous development of new energy, batteries are widely used in vehicles to provide electric drive for vehicles. How to improve the safety of battery use is an urgent problem to be solved. Utility Model Content

[0003] In view of the above problems, the present application provides a battery cell, a battery and an electrical device to improve the safety of battery use.

[0004] In the first aspect of the present application, a battery cell includes a shell and an explosion-proof valve sheet, wherein the shell includes a shell wall, and the shell wall has an exhaust passage that penetrates in the wall thickness direction. The explosion-proof valve sheet is arranged on the shell wall and is used to cover the exhaust passage, the explosion-proof valve sheet includes a reversing groove and a cracking groove, the groove depth of the reversing groove is less than the groove depth of the cracking groove, and the cracking groove is configured to rupture under the action of the air pressure in the shell so that part of the explosion-proof valve sheet is reversed outward around the reversing groove relative to the shell wall to open the exhaust passage, and the explosion-proof valve sheet includes a stamping area. The thickness of the stamping area is less than the thickness of the remaining unstamped area of ​​the explosion-proof valve sheet, the reversing groove and the cracking groove are provided in the stamping area, and the difference between the first residual thickness of the explosion-proof valve sheet at the reversing groove and the second residual thickness of the explosion-proof valve sheet at the cracking groove is less than the difference between the thickness of the explosion-proof valve sheet at the stamping area and the second residual thickness.

[0005] The technical solution of the embodiment of the present application is to set a cracking groove on the explosion-proof valve sheet, and the groove depth of the reversing groove is less than the groove depth of the cracking groove. When the battery cell has thermal runaway, the cracking groove of the explosion-proof valve sheet will crack under the action of air pressure, so that part of the valve sheet of the explosion-proof valve sheet will be turned outward around the reversing groove to open the exhaust channel, so that the high-temperature and high-pressure gas and other media generated by thermal runaway can be discharged to the outside of the shell through the exhaust channel, thereby avoiding explosion. The embodiment of the present application sets a stamping area on the explosion-proof valve sheet, and sets a reversing groove and a cracking groove in the stamping area, so that the stamping area is wrapped by the unstamped area. In this way, when thermal runaway occurs, the high-temperature and high-pressure medium that rushes out is blocked by the unstamped area and is not easily discharged to other places of the shell wall, thereby avoiding greater heat diffusion.

[0006] In some embodiments, the ratio (D1-D2) / (D3-D2) between the difference between the first residual thickness of the explosion-proof valve plate at the flip groove and the second residual thickness of the explosion-proof valve plate at the cracking groove and the difference between the thickness of the explosion-proof valve plate at the stamping area and the second residual thickness is less than or equal to 0.7.

[0007] If the above ratio is too large, the rigidity of the flip groove will be too large, and it will be difficult for the explosion-proof valve sheet to flip along the flip groove after thermal runaway of the battery, resulting in oblique spraying, and a high risk of the explosion-proof valves of adjacent battery cells being melted through.

[0008] In some embodiments, the ratio (D1-D2) / (D3-D2) between the difference between the first residual thickness of the explosion-proof valve plate at the flip groove and the second residual thickness of the explosion-proof valve plate at the cracking groove and the difference between the thickness of the explosion-proof valve plate at the stamping area and the second residual thickness is greater than or equal to 0.3.

[0009] When the above ratio is too small, the connection strength of the flip groove is too low. After the battery thermal runaway, the explosion-proof valve piece will detach from the shell and fall into the high-voltage connection area, increasing the risk of insulation failure.

[0010] In some embodiments, the ratio of the difference between the first residual thickness of the explosion-proof valve sheet at the flip groove and the second residual thickness of the explosion-proof valve sheet at the cracking groove to the difference between the thickness of the explosion-proof valve sheet at the stamping area and the second residual thickness is 0.3≤(D1-D2) / (D3-D2)≤0.7.

[0011] In some embodiments, 0.4≤(D1-D2) / (D3-D2)≤0.6.

[0012] In some embodiments, the explosion-proof valve disc is in an oblong shape, and the flip groove is a straight line segment extending along the length direction of the explosion-proof valve disc.

[0013] The explosion-proof valve plate of the embodiment of the present application is set to an oblong shape, which can increase the flow area of ​​the exhaust gas and further accelerate the discharge speed of the high-temperature and high-pressure gas when thermal runaway occurs. In addition, the reversal groove is set to a straight line segment extending along the length direction of the explosion-proof valve plate, so that when the explosion-proof valve plate is reversed, its reversal axis is formed by the reversal groove of the straight line segment, that is, a straight reversal axis is formed, so that when part of the valve plate is reversed upward to open the exhaust channel, the opening angle of the explosion-proof valve plate will be larger, which is more conducive to the discharge of the thermal runaway medium.

[0014] In some embodiments, the flip groove and the crack initiation groove are connected end to end to form a closed annular groove. In the length direction, the ratio between the size of the flip groove and the size of the explosion-proof valve sheet is 0.15≤L1 / L2≤0.65. When L1 / L2 is too large, the rigidity of the flip groove is too large, and the explosion-proof valve sheet is difficult to flip along the flip groove after the battery thermal runaway, and oblique spraying will occur. The risk of the explosion-proof valve sheets of adjacent battery cells being melted through is high. When L1 / L2 is too small, the connection strength of the flip groove is too low, and the explosion-proof valve sheet will detach from the shell after the battery thermal runaway and fall into the high-voltage connection area, increasing the risk of insulation failure.

[0015] In some embodiments, the ratio between the size of the inversion groove and the size of the explosion-proof valve disc is 0.3≤L1 / L2≤0.5.

[0016] A second aspect of the present application provides a battery, comprising the above-mentioned battery cell.

[0017] A third aspect of the present application provides an electrical device, comprising the above-mentioned battery, for providing electrical energy.

[0018] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of the structure of a vehicle according to some embodiments of the present application.

[0021] Figure 2 It is a schematic diagram of the exploded structure of the battery of some embodiments of the present application.

[0022] Figure 3 It is a schematic diagram of the structure of a battery cell in some embodiments of the present application.

[0023] Figure 4 It is a schematic diagram of the structure of explosion-proof valve plates in some embodiments of the present application.

[0024] Figure 5 yes Figure 4 The schematic diagram of the cross-sectional structure of the explosion-proof valve piece in the AA direction is shown.

[0025] Figure 6 yes Figure 4 The cross-sectional structure diagram of the explosion-proof valve piece is shown.

[0026] In the drawings, the drawings are not drawn to scale.

[0027] 2000. Vehicles.

[0028] 1000.Battery.

[0029] 200, battery box; 210, lower box body; 220, upper box body.

[0030] 100. Battery module.

[0031] 10. Battery cell.

[0032] 11. shell; 111. shell wall; 1111. exhaust passage.

[0033] 12. explosion-proof valve disc; 12a. stamping area; 121. turning groove; 122. cracking groove. DETAILED DESCRIPTION

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0035] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0036] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0037] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0038] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0039] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0040] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0041] At present, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric vehicles, as well as aerospace and other fields. With the continuous expansion of the application field of power batteries, its market demand is also growing.

[0042] The power-consuming device of the embodiment of the present application may be a mobile device such as a vehicle, a ship, a small aircraft, etc. Taking a vehicle as an example, the vehicle of the embodiment of the present application may be a new energy vehicle. The new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle. Figure 1 A vehicle 2000 using a battery 1000 as a power source is shown. The battery 1000 is disposed in the vehicle 2000. A drive motor is disposed in the vehicle 2000, the drive motor is electrically connected to the battery 1000, the battery 1000 provides electrical energy to the drive motor, and the drive motor is connected to the wheels through a transmission mechanism to drive the vehicle to move. Specifically, the battery 1000 can be horizontally disposed at the bottom of the vehicle 2000.

[0043] The battery 1000 of the embodiment of the present application includes at least one battery module 100. Specifically in this embodiment, Figure 2 As shown, the battery 1000 of this embodiment includes a battery module 100 and a battery box 200 for accommodating the battery module 100. The battery box 200 has a receiving cavity, and the battery module 100 is arranged in the receiving cavity. Figure 2In the illustrated embodiment, the battery box 200 includes a lower box body 210 and an upper box body 220 that cover each other. The upper box body 220 and the lower box body 210 together define a storage space for accommodating the battery module 100. Of course, in some other embodiments, the battery 1000 may also include a cover body that covers the lower box body 210, and the cover body may be a plate-like structure, for example. Of course, the shape of the battery box 200 may be a variety of shapes, such as a cuboid, a cylinder, etc.

[0044] refer to Figure 3 The battery module 100 includes a plurality of battery cells 10. The plurality of battery cells 10 are electrically connected via a connecting sheet. The plurality of battery cells 10 can be connected in series, in parallel, or in a mixed connection under the connection of the connecting sheet. Of course, the battery module is only used to describe an array formed by a plurality of battery cells. The battery module can be a battery module in which a plurality of battery cells are first connected in series, in parallel, or in a mixed connection, and then a plurality of battery modules are connected in series, in parallel, or in a mixed connection to form a whole. The battery module can also refer to a battery module.

[0045] The battery cell 10 refers to the smallest unit constituting the battery module. The battery cell 10 may include a lithium-ion secondary battery, a lithium-ion primary battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery or a magnesium-ion battery, etc. The present application embodiment is not limited to this.

[0046] The battery cell 10 includes a shell 11, an electrode assembly and other functional components. The inner cavity of the shell 11 is used to accommodate the electrode assembly, electrolyte and other components. The shell includes a shell body and an end cover, and an opening is provided on the shell body. The end cover is closed at the opening to form the internal environment of the battery cell. The shell can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present disclosure do not impose any special restrictions on this.

[0047] The electrode assembly is a component in a battery cell where electrochemical reactions occur. One or more electrode assemblies may be contained in the housing. The electrode assembly is mainly formed by winding or stacking positive and negative electrode sheets. During the charge and discharge process of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte, and the pole lugs connect the poles to form a current loop. The electrode assembly may be a winding structure or a stacked structure, and the embodiments of the present application are not limited thereto.

[0048] An explosion-proof valve is a component or part that opens to release the internal pressure or temperature of a battery cell when the internal pressure or temperature reaches a predetermined threshold. Therefore, when a battery experiences thermal runaway, how to ensure that the explosion-proof valve opens quickly to reduce the risk of battery cell explosion and improve battery safety is an urgent problem to be solved.

[0049] In response to the above problems, an embodiment of the present application provides a battery cell, the explosion-proof valve of the battery cell includes an explosion-proof valve plate, and the explosion-proof valve plate includes a cracking groove, so that when the battery suffers from thermal runaway, the cracking groove will rupture under the action of air pressure, thereby causing part of the explosion-proof valve plate to flip relative to the shell around the flip groove to open the exhaust channel, reducing the risk of explosion of the battery cell and thus improving the safety of battery use.

[0050] According to the following Figures 3 to 6 The structure and working process of the battery cells in some embodiments of the present application are described in detail.

[0051] refer to Figures 3 to 6 , the battery cell 10 provided in some embodiments of the present application includes a shell 11 and an explosion-proof valve plate 12. The shell 11 includes a shell wall 111. The shell wall 111 has an exhaust channel 1111 that runs through in the wall thickness direction. The explosion-proof valve plate 12 is arranged on the shell wall 111 and is used to cover the exhaust channel 1111. The explosion-proof valve plate 12 includes a flip groove 121 and a cracking groove 122. The groove depth of the flip groove 121 is less than the groove depth of the cracking groove 122, and the cracking groove 122 is configured to rupture under the action of the air pressure in the shell 11 so that part of the valve plate of the explosion-proof valve plate 12 flips outward around the flip groove 121 relative to the shell wall 111, thereby opening the exhaust channel 1111. Figure 4 As shown, the explosion-proof valve plate 12 includes a stamping area 12a. The thickness of the stamping area is less than the thickness of the remaining unstamped areas of the explosion-proof valve plate, and the overturning groove and the cracking groove are opened in the stamping area. The difference between the first residual thickness D1 of the explosion-proof valve plate 12 at the overturning groove and the second residual thickness D2 of the explosion-proof valve plate 12 at the cracking groove is less than the difference between the thickness D3 of the explosion-proof valve plate 12 at the stamping area 12a and the second residual thickness D2.

[0052] like Figure 3 As shown, the battery cell 10 includes a shell 11. The shell 11 includes a shell body and an end cover covered on the shell body. The shell wall 111 described in the embodiment of the present application includes multiple walls of the shell body and an end cover. Figure 3 In the specific embodiment shown, the housing 11 is a rectangular parallelepiped structure, so it includes six shell walls 111. Usually, the explosion-proof valve plate 12 is arranged on the end cover or on the bottom wall opposite to the end cover. In other embodiments not shown in the drawings, the housing 11 can also be in a shape such as a cylinder, and the embodiment of the present application does not limit this. For the cylindrical housing 11, the explosion-proof valve plate 12 is generally arranged on the axial end cover.

[0053] like Figure 3As shown, the shell wall 111 has an exhaust passage 1111 that runs through in the wall thickness direction, that is, the exhaust passage is used to connect the inner cavity of the shell 11 with the outside. During the normal operation of the battery cell 10, the explosion-proof valve sheet 12 is connected to the shell wall 111 and covers the exhaust passage 1111, so that the explosion-proof valve sheet 12 plays the role of sealing the shell to prevent the electrolyte in the shell from flowing out. When the battery cell 10 has thermal runaway, the cracking groove 122 of the explosion-proof valve sheet 12 will crack under the action of air pressure, so that part of the valve sheet of the explosion-proof valve sheet 12 will flip outward around the flip groove 121 to open the exhaust passage, so that the high-temperature and high-pressure gas and other media generated by thermal runaway can be discharged to the outside of the shell through the exhaust passage, thereby avoiding explosion.

[0054] like Figure 4 As shown, a crack initiation groove 122 and a reversal groove 121 are provided on the explosion-proof valve plate 12 of the embodiment of the present application. The groove depth of the reversal groove 121 is less than the groove depth of the crack initiation groove 122, which will make the thickness of the valve plate of the explosion-proof valve plate 12 located at the crack initiation groove 122 smaller. Therefore, if thermal runaway occurs, the crack initiation groove 122 will crack, thereby causing part of the valve plate of the explosion-proof valve plate to flip open. In some embodiments, the crack initiation groove 122 includes a straight crack initiation section extending along the length direction of the explosion-proof valve plate 12 and an arc-shaped crack initiation section extending from the end of the straight crack initiation section toward the width direction. In this way, when thermal runaway occurs in the battery cell, the crack initiation groove 122 will crack to a larger extent, thereby causing the explosion-proof valve plate 12 to flip open to a higher degree, so that the high-temperature and high-pressure gas inside the battery cell can be discharged in time.

[0055] like Figure 4 As shown, the circumferential edge of the explosion-proof valve disc 12 of this embodiment is connected to the shell wall 111, and the crack initiation groove 122 and the flip groove 121 are arranged on the inner side of the circumferential edge of the explosion-proof valve disc 12. When the crack initiation groove 122 ruptures and part of the valve disc flips open, the circumferential edge of the explosion-proof valve disc 12 still remains connected to the shell wall 111.

[0056] The technical solution of the embodiment of the present application is to set a cracking groove 122 on the explosion-proof valve sheet 12, and the groove depth of the reversing groove is less than the groove depth of the cracking groove. When the battery cell 10 has thermal runaway, the cracking groove 122 of the explosion-proof valve sheet 12 will crack under the action of air pressure, so that part of the valve sheet of the explosion-proof valve sheet 12 will be turned outward around the reversing groove 121 to open the exhaust channel, so that the high-temperature and high-pressure gas and other media generated by thermal runaway can be discharged to the outside of the shell through the exhaust channel, thereby avoiding explosion. The embodiment of the present application sets a stamping area on the explosion-proof valve sheet, and sets a reversing groove and a cracking groove in the stamping area, so that the stamping area is wrapped by the unstamped area. In this way, when thermal runaway occurs, the high-temperature and high-pressure medium that rushes out is blocked by the unstamped area and is not easily discharged to other places of the shell wall, thereby avoiding greater heat diffusion.

[0057] In some embodiments, the ratio of the difference between the first residual thickness D1 of the explosion-proof valve plate 12 at the flip groove and the second residual thickness D2 of the explosion-proof valve plate 12 at the crack initiation groove to the difference between the thickness D3 of the explosion-proof valve plate 12 at the stamping area 12a and the second residual thickness D2 is (D1-D2) / (D3-D2)≤0.7.

[0058] like Figure 6 As shown, the first residual thickness D1 refers to the remaining thickness of the stamping area 12a after the reversing groove 121 is opened, that is, the first residual thickness D1 is equal to the difference between the thickness D3 of the stamping area 12a and the groove depth d1 of the reversing groove 121. The second residual thickness D2 refers to the remaining thickness of the stamping area 12a after the cracking groove 122 is opened, that is, the second residual thickness D2 is equal to the difference between the thickness D3 of the stamping area 12a and the groove depth d2 of the cracking groove 122. The thickness D3 of the stamping area 12a refers to the thickness of the ungrooved area of ​​the stamping area 12a. Then the difference between the first residual thickness D1 of the explosion-proof valve plate 12 at the reversing groove 121 and the second residual thickness D2 of the explosion-proof valve plate 12 at the cracking groove 122 is equal to the difference between the groove depth d2 of the cracking groove 122 and the groove depth d1 of the reversing groove 121. Furthermore, the difference between the thickness D3 of the explosion-proof valve plate 12 at the stamping area 12a and the second residual thickness D2 is equal to the groove depth d2 of the crack initiation groove 122. That is, (D1-D2) / (D3-D2)=(d2-d1) / d2, so if (d2-d1) / d2 is set to be less than or equal to 0.7, it can be deduced that d1 / d2≥0.3, that is, the ratio between the groove depth d1 of the turnover groove 121 and the groove depth d2 of the crack initiation groove 122 is greater than or equal to 0.3.

[0059] If the ratio between d1 and d2 is too large, the rigidity of the flip groove will be too large. After the battery thermal runaway, the explosion-proof valve piece will be difficult to flip along the flip groove, and oblique spraying will occur. There is a high risk that the explosion-proof valves of adjacent battery cells will be melted through.

[0060] On the other hand, (D1-D2) / (D3-D2)=(d2-d1) / d2, so if (d2-d1) / d2 is greater than or equal to 0.3, it can be deduced that d1 / d2≤0.7. When the above ratio is too small, the connection strength of the flip slot is too low, and the explosion-proof valve sheet will detach from the shell after the battery thermal runaway and fall into the high-voltage connection area, increasing the risk of insulation failure.

[0061] In some embodiments, the ratio of the difference between the first residual thickness D1 of the explosion-proof valve plate 12 at the flip groove and the second residual thickness D2 of the explosion-proof valve plate 12 at the crack initiation groove to the difference between the thickness D3 of the explosion-proof valve plate 12 at the stamping area 12a and the second residual thickness D2 is 0.4≤(D1-D2) / (D3-D2)≤0.6.

[0062] In some embodiments, the explosion-proof valve disc 12 is in an oblong shape. The flip groove 121 is a straight line segment extending along the length direction X of the explosion-proof valve disc 12 .

[0063] like Figure 3 As shown, the exhaust channel 1111 is an oblong hole, and accordingly, the explosion-proof valve disc 12 is an oblong valve disc. The flip groove 121 is opened on the inner side of the edge of the explosion-proof valve disc 12 and extends along the length direction X of the explosion-proof valve disc 12.

[0064] The explosion-proof valve disc 12 of the embodiment of the present application is set to an oblong shape, which can increase the flow area of ​​the exhaust gas and further accelerate the discharge speed of the high-temperature and high-pressure gas when thermal runaway occurs. In addition, the reversal groove 121 is set to a straight line segment extending along the length direction X of the explosion-proof valve disc 12, so that when the explosion-proof valve disc 12 is reversed, its reversal axis is formed by the reversal groove 121 of the straight line segment, that is, a straight reversal axis is formed, so that when part of the valve disc is reversed upward to open the exhaust channel, the opening angle of the explosion-proof valve disc 12 will be larger, which is more conducive to the discharge of the thermal runaway medium.

[0065] It should also be noted that the straight line segment mentioned here may be an approximate straight line, and does not represent an absolute straight line. Some positions of the flip groove 121 may have deviations within the allowable range of processing.

[0066] In some embodiments, the turnover groove is connected to the crack initiation groove to form a closed annular groove. In the length direction X, the ratio between the size L1 of the turnover groove 121 and the size L2 of the explosion-proof valve disc 12 is less than or equal to 0.65.

[0067] like Figure 4As shown, the explosion-proof valve sheet 12 of this embodiment is an oblong. Therefore, its dimension L2 in the length direction is greater than its dimension in the width direction. And the dimension L1 of the reversal groove here refers to the dimension of the reversal groove 121 extending in the length direction of the explosion-proof valve sheet 12. The inventor of the present application found in the research process that the part where the reversal groove 121 is located forms the reversal axis of the explosion-proof valve sheet, and the part where the cracking groove 122 is located will be split and opened upward. Since the reversal groove 121 and the cracking groove 122 are connected end to end to form a closed annular groove, the total extension length of the reversal groove 121 and the cracking groove 122 is determined, so the length of the reversal groove 121 will affect the length of the cracking groove 122. If the length of the reversal groove 121 is set to a large value, the length of the cracking groove 122 will be reduced accordingly, thereby making the ruptured part smaller, which also makes the rigidity of the explosion-proof valve sheet larger. After the battery cell has thermal runaway, the explosion-proof valve sheet is difficult to flip, and the opening angle is very small, and the phenomenon of oblique spraying will occur, which increases the risk of the explosion-proof valve sheet of the adjacent battery cell being melted through. After testing, the embodiment of the present application proposes that the ratio between the size L1 of the flip groove 121 and the size L2 of the explosion-proof valve plate 12 be less than or equal to 0.65. Within this range, the explosion-proof valve plate can be smoothly flipped and opened at a larger angle, thereby avoiding the risk of high-temperature materials spraying obliquely and causing the explosion-proof valve plates of other battery cells to be melted through, thereby improving the overall safety of the battery.

[0068] The ratio between the size L1 of the flip groove 121 and the size L2 of the explosion-proof valve plate 12 in the embodiment of the present application is less than or equal to 0.65. Within this ratio range, the explosion-proof valve plate can be smoothly flipped and opened at a larger angle, thereby avoiding the risk of high-temperature materials spraying obliquely and causing the explosion-proof valve plates of other battery cells to be melted through, thereby improving the overall safety of the battery.

[0069] Since the flip groove 121 not only serves as the flip axis but also serves to connect the flipped open part of the valve disc, if the size L1 of the flip groove 121 is set too small, the flip groove 121 may also crack when the internal air pressure is too high, causing part of the explosion-proof valve disc to directly separate from the shell. If it falls into the high-voltage connection area, it will cause insulation failure and other safety problems.

[0070] To address this problem, in some embodiments, in the length direction X, the ratio between the size L1 of the inversion groove 121 and the size of the explosion-proof valve disc 12 is greater than or equal to 0.15.

[0071] After testing, the ratio between the size L1 of the flip groove 121 and the size of the explosion-proof valve plate 12 is set to be greater than or equal to 0.15. This can effectively ensure that after thermal runaway occurs, part of the valve plate of the explosion-proof valve plate can remain connected to the shell when it is open, avoiding detachment from the shell and causing other safety problems, thereby further improving the safety of battery cells.

[0072] In some embodiments, in the length direction, the ratio between the size L1 of the turnover groove 121 and the size L2 of the explosion-proof valve disc 12 is 0.15≤L1 / L2≤0.65.

[0073] Preferably, in some embodiments, the ratio between the size L1 of the turnover groove and the size L2 of the explosion-proof valve disc 12 is 0.3≤L1 / L2≤0.5.

[0074] When L1 / L2 is too large, the rigidity of the rollover groove is too large, and the explosion-proof valve piece is difficult to roll along the rollover groove after the battery thermal runaway, which will cause oblique spraying and a high risk of the explosion-proof valve piece of the adjacent battery cell being melted through. When L1 / L2 is too small, the connection strength of the rollover groove is too low, and the explosion-proof valve piece will detach from the shell after the battery thermal runaway and fall into the high-voltage connection area, increasing the risk of insulation failure.

[0075] In some embodiments, the depth of the flip groove 121 is less than the depth of the cracking groove 122. The depth of the flip groove 121 is set to be less than the depth of the cracking groove 122, so that the position where the cracking groove 122 is located is more likely to be broken, while the position where the flip groove 121 is located can remain connected to prevent separation from the shell.

[0076] like Figure 5 and Figure 6 As shown, in some embodiments, the explosion-proof valve sheet 12 includes a stamping area 12a. The thickness of the stamping area 12a is less than the thickness of the remaining unstamped areas of the explosion-proof valve sheet 12, and the overturning groove 121 and the cracking groove 122 are opened in the stamping area 12a. The difference between the first residual thickness D1 of the explosion-proof valve sheet 12 at the overturning groove 121 and the second residual thickness D2 of the explosion-proof valve sheet 12 at the cracking groove 122 is less than the difference between the thickness D3 of the explosion-proof valve sheet 12 at the stamping area 12a and the second residual thickness D2.

[0077] An embodiment of the present application also provides a battery, comprising the above-mentioned battery cell.

[0078] The embodiment of the present application further provides an electrical device, comprising the above-mentioned battery. The battery is used to provide electrical energy.

[0079] According to the following Figures 3 to 6 The structure of a battery cell according to a specific embodiment of the present application is described in detail.

[0080] like Figure 3 As shown, the battery cell 10 of this embodiment includes a shell 11 and an explosion-proof valve sheet 12. The shell 11 is a rectangular parallelepiped and includes a plurality of shell walls 111. The shell wall 111 includes an exhaust passage 1111. The explosion-proof valve sheet 12 is connected to the shell wall 111 to cover the exhaust passage 1111. Specifically, the circumferential edge of the explosion-proof valve sheet 12 is welded to the shell wall 111.

[0081] like Figure 4 As shown, the explosion-proof valve disc 12 includes a stamping area 12a located in the middle and an unstamped area enclosed in the circumferential direction of the stamping area 12a. The explosion-proof valve disc 12 includes an annular groove extending in the circumferential direction of the stamping area 12a and closed. The annular groove includes a turnover groove 121 and a cracking groove 122. That is, the turnover groove 121 and the cracking groove 122 are connected end to end to form a closed annular groove. The explosion-proof valve disc 12 is oblong, and the annular groove is also oblong.

[0082] The depth of the reversal groove 121 is less than the depth of the cracking groove 122. When the internal pressure of the shell 11 of the battery cell 10 reaches a threshold, the cracking groove 122 ruptures and expands, causing the explosion-proof valve sheet to reversal along the reversal groove 121, so that the high-pressure gas in the shell 11 can be discharged in time.

[0083] In this embodiment, if Figure 4 As shown, the extension direction of the flip groove 121 is consistent with the length direction of the oblong explosion-proof valve plate 12, and it is a straight groove. The cracking groove 122 includes a cracking straight line segment arranged opposite to the flip groove 121 and two connecting segments respectively arranged at both ends of the cracking straight line segment. The connecting segment includes an arc-shaped connecting segment and a straight connecting segment connected to the flip groove 121. In this way, the extension range of the cracking groove 122 is expanded to both ends of the flip groove 121, thereby making the angle of the explosion-proof valve plate flip open larger, so that the high-temperature and high-pressure gas is directly ejected upward through the exhaust channel, avoiding oblique spraying and affecting other battery cells.

[0084] The length L1 of the turnover groove 121 and the length L2 of the explosion-proof valve plate 12 satisfy:

[0085] 0.15≤L1 / L2≤0.65, preferably 0.3≤L1 / L2≤0.5.

[0086] When L1 / L2 is too large, the rigidity of the rollover groove is too large, and the explosion-proof valve piece is difficult to roll along the rollover groove after the battery cell thermal runaway, which will cause oblique spraying and a high risk of the explosion-proof valve piece of the adjacent battery cell being melted through. When L1 / L2 is too small, the connection strength of the rollover groove is too low, and the explosion-proof valve piece is easy to detach from the shell after the battery cell thermal runaway. If detachment occurs, it will fall into the high-voltage connection area, increasing the risk of insulation failure.

[0087] In this embodiment, the above range is determined by conducting a thermal runaway test on the battery cell, and the test method is as follows:

[0088] Select the heating plate according to the size of the battery cell. The size of the heating plate should cover as much of the battery cell as possible (coverage area ≥ 60%). The large surface refers to the largest surface among the multiple surfaces of the battery cell.

[0089] Before testing, charge the battery cells to 100% SOC and ensure that the battery cell temperature is 25±5℃.

[0090] Assemble the fixture so that it completely covers the large surface of the battery cell, and set the clamping force to 3000 N. Note: The arrangement order of the fixture, heating plate and battery cell is: fixture + heating plate + battery cell + fixture.

[0091] In the test, the heating plate was turned on at a power of 500W to heat the battery cell until the battery cell thermally ran away.

[0092] Thermal runaway criteria: a) The trigger object generates a voltage drop, and the voltage drops to more than 25% of the initial voltage; b) The temperature at the detection point reaches the preset maximum operating temperature; c) The temperature rise rate dT / dt at the detection point is ≥1℃ / s, and lasts for more than 3s. When a) and c) or b) and c) occur, thermal runaway is determined to have occurred.

[0093] The test results of battery cells with different lengths of flip slots are shown in the following table:

[0094]

[0095] As can be seen from the table above, in Example 1, L1 / L2 is greater than the maximum value, resulting in insufficient flipping angle of the explosion-proof plate after thermal runaway of the battery, causing oblique spraying and melting of the explosion-proof valve of the adjacent battery cell. In Example 2, L1 / L2 is less than the minimum value, resulting in the explosion-proof valve plate being separated from the shell after thermal runaway of the battery, increasing the risk of system insulation failure.

[0096] like Figure 6 As shown, in order to further optimize the explosion-proof effect of the explosion-proof valve plate of the embodiment of the present application, the ratio of the difference between the first residual thickness D1 of the explosion-proof valve plate 12 at the flip groove and the second residual thickness D2 of the explosion-proof valve plate 12 at the crack initiation groove and the difference between the thickness D3 of the explosion-proof valve plate 12 at the stamping area 12a and the second residual thickness D2 is 0.3≤(D1-D2) / (D3-D2)≤0.7.

[0097] The above thermal runaway test method was also used to test explosion-proof valve plates with different residual thicknesses. The test results are as follows:

[0098]

[0099] In comparative example 1, (D1-D2) / (D3-D2) is less than the minimum value, which causes the explosion-proof valve sheet to separate from the shell after the battery thermal runaway, resulting in an increased risk of system insulation failure. In comparative example 2, (D1-D2) / (D3-D2) is greater than the maximum value, which causes the explosion-proof valve sheet to have an insufficient flip angle after the battery thermal runaway, resulting in oblique spraying and the explosion-proof valves of adjacent cells being melted through.

[0100] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: A shell (11) comprising a shell wall (111), wherein the shell wall (111) has an exhaust passage (1111) penetrating in a wall thickness direction; and an explosion-proof valve disc (12), the explosion-proof valve disc (12) being arranged on the shell wall (111) and used for covering the exhaust passage (1111), the explosion-proof valve disc (12) comprising a turnover groove (121) and a crack initiation groove (122), the groove depth of the turnover groove (121) being smaller than the groove depth of the crack initiation groove (122), the crack initiation groove (122) being configured to rupture under the action of the air pressure in the shell (11) so that a portion of the explosion-proof valve disc (12) is turned outward relative to the shell wall (111) around the turnover groove (121) to thereby open the exhaust passage (1111); The explosion-proof valve plate (12) comprises a stamping area (12a), the thickness of the stamping area (12a) is smaller than the thickness of the remaining un-stamped areas of the explosion-proof valve plate (12), the turnover groove (121) and the crack initiation groove (122) are arranged in the stamping area (12a), and the difference between a first residual thickness (D1) of the explosion-proof valve plate (12) located at the turnover groove and a second residual thickness (D2) of the explosion-proof valve plate (12) located at the crack initiation groove is smaller than the difference between a thickness (D3) of the explosion-proof valve plate (12) located at the stamping area (12a) and the second residual thickness (D2).

2. The battery cell according to claim 1, characterized in that: The ratio (D1-D2) / (D3-D2) between the difference between the first residual thickness (D1) of the explosion-proof valve plate (12) at the turnover groove and the second residual thickness (D2) of the explosion-proof valve plate (12) at the crack initiation groove and the difference between the thickness (D3) of the explosion-proof valve plate (12) at the stamping area (12a) and the second residual thickness (D2) is less than or equal to 0.

7.

3. The battery cell according to claim 1, characterized in that: The ratio (D1-D2) / (D3-D2) between the difference between the first residual thickness (D1) of the explosion-proof valve plate (12) at the turnover groove and the second residual thickness (D2) of the explosion-proof valve plate (12) at the crack initiation groove and the difference between the thickness (D3) of the explosion-proof valve plate (12) at the stamping area (12a) and the second residual thickness (D2) is greater than or equal to 0.

3.

4. The battery cell according to claim 1, characterized in that: The ratio between the difference between a first residual thickness (D1) of the explosion-proof valve plate (12) at the turnover groove and a second residual thickness (D2) of the explosion-proof valve plate (12) at the crack initiation groove and the difference between a thickness (D3) of the explosion-proof valve plate (12) at the stamping area (12a) and the second residual thickness (D2) is 0.3≤(D1-D2) / (D3-D2)≤0.

7.

5. The battery cell according to claim 4, characterized in that: 0.4≤(D1-D2) / (D3-D2)≤0.

6.

6. The battery cell according to any one of claims 1 to 5, characterized in that: The explosion-proof valve disc (12) is in the shape of an oblong circle, and the turnover groove (121) is a straight line segment extending along the length direction (X) of the explosion-proof valve disc (12).

7. The battery cell according to claim 6, characterized in that: The reversal groove (121) and the crack initiation groove (122) are connected end to end to form a closed annular groove, and in the length direction, the ratio between the size (L1) of the reversal groove and the size (L2) of the explosion-proof valve plate (12) is 0.15≤L1 / L2≤0.

65.

8. The battery cell according to claim 7, characterized in that: The ratio between the size (L1) of the turnover groove and the size (L2) of the explosion-proof valve plate (12) is 0.3≤L1 / L2≤0.

5.

9. A battery, characterized in that: The invention comprises the battery cell according to any one of claims 1 to 8.

10. An electrical device, characterized in that: Comprising a battery as claimed in claim 9, the battery is used to provide electrical energy.

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