Explosion-proof valve for secondary battery top cover, top cover assembly, secondary battery and automobile

Abstract

This application relates to an explosion-proof valve for a secondary battery top cover, a top cover assembly, a secondary battery, and an automobile. The explosion-proof valve includes a flat base and a raised portion protruding outward from the flat base. The raised portion has a horizontal groove and a branch groove connected to one end of the horizontal groove, the horizontal groove and the branch groove forming a non-zero angle. The explosion-proof valve includes a raised portion protruding outward from the top cover assembly relative to the flat base. The raised portion has a horizontal groove and a branch groove connecting to the horizontal groove. When the pressure inside the housing increases excessively, gas stress concentrates at the raised portion and tears the explosion-proof valve through the horizontal groove and the branch groove, allowing the gas inside the housing to be released. This reduces the risk of secondary battery explosion and improves the safety of the secondary battery.

Description

Technical Field

[0001] This application relates to the field of energy storage device technology, and in particular to an explosion-proof valve for a secondary battery top cover, a top cover assembly, a secondary battery, and an automobile. Background Technology

[0002] Secondary batteries can be charged and discharged. If a secondary battery is subjected to conditions such as overcharging, having its electrodes punctured by a metal conductor, or being tested in a hot chamber, heat and gas will rapidly accumulate inside the secondary battery, causing an increase in internal pressure. In severe cases, this can lead to the secondary battery expanding and exploding.

[0003] Secondary batteries are usually equipped with explosion-proof valves. When the internal pressure of the secondary battery increases to the opening pressure of the explosion-proof valve, the internal gas is released from the explosion-proof valve, thereby preventing dangerous accidents such as explosion of the secondary battery. Summary of the Invention

[0004] This application provides an explosion-proof valve for a secondary battery top cover, a top cover assembly, a secondary battery, and an automobile, aiming to improve the safety of secondary batteries.

[0005] This application provides an explosion-proof valve for a secondary battery top cover. The explosion-proof valve includes a flat base and a raised portion protruding outward relative to the flat base. The raised portion is provided with a horizontal and vertical groove and a branch groove connected to one end of the horizontal and vertical groove. The horizontal and vertical groove and the branch groove form a non-zero angle.

[0006] Optionally, the raised portion has a ridge-shaped sharp angle, and the inner surface of the explosion-proof valve opposite to the raised portion has a recess corresponding to the shape of the raised portion.

[0007] Optionally, both the horizontal and vertical notches and the branching notches are located at the top of the ridge-like sharp corner, and / or

[0008] Both the horizontal and vertical grooves and the branch grooves are located at the bottom of the recessed portion, corresponding to the ridge-shaped sharp corner.

[0009] Optionally, there are two branch marks, and the horizontal and vertical marks and the two branch marks are Y-shaped.

[0010] Optionally, the two branch marks are symmetrical with respect to the horizontal and vertical marks, and both ends of the horizontal and vertical marks are connected to the two branch marks.

[0011] Optionally, the angle between the branch groove and the horizontal groove is 120° to 150°.

[0012] Optionally, the length of the horizontal or vertical groove is 1.5 to 2.5 times the length of the branch groove.

[0013] Optionally, the explosion-proof valve further includes a transition portion, the raised portion being connected to the flat base portion via the transition portion, and the transition portion being inclined relative to the flat base portion.

[0014] Optionally, the tilt angle of the transition section is 2° to 15°.

[0015] This application also provides a secondary battery top cover assembly, including a top cover sheet and an explosion-proof valve connected to the top cover sheet, wherein the explosion-proof valve is any of the explosion-proof valves described above.

[0016] This application also provides a secondary battery, comprising:

[0017] Electrode assembly;

[0018] The shell has an opening;

[0019] And the aforementioned secondary battery top cover assembly,

[0020] The secondary battery top cover assembly is connected to the opening of the housing and forms an encapsulation space. The electrode assembly is encapsulated within the encapsulation space, and the raised portion protrudes in a direction away from the electrode assembly.

[0021] This application also provides a vehicle including the aforementioned secondary battery.

[0022] The technical solution provided in this application can achieve the following beneficial effects:

[0023] This application provides an explosion-proof valve for a secondary battery top cover assembly. The explosion-proof valve includes a raised portion protruding outward relative to a flat base. The raised portion is provided with horizontal and vertical grooves and branch grooves connecting the horizontal and vertical grooves. When the pressure inside the housing increases excessively, the gas generates stress concentration at the raised portion and tears the explosion-proof valve from the horizontal and vertical grooves and the branch grooves, allowing the gas inside the housing to be released. This reduces the risk of secondary battery explosion and improves the safety of the secondary battery.

[0024] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0025] Figure 1 An exploded view of a secondary battery provided in an embodiment of this application;

[0026] Figure 2 This is a top view of the secondary battery top cover assembly provided in an embodiment of this application;

[0027] Figure 3 An exploded view of the secondary battery top cover assembly provided in an embodiment of this application;

[0028] Figure 4 A schematic diagram of the explosion-proof valve of the secondary battery top cover assembly provided in the embodiments of this application;

[0029] Figure 5 A cross-sectional view of a portion of the structure of the explosion-proof valve provided in an embodiment of this application;

[0030] Figure 6 A cross-sectional view of a portion of the structure of an explosion-proof valve provided in another embodiment of this application.

[0031] Figure label:

[0032] 1000-secondary battery;

[0033] 100 - Housing;

[0034] 200 - Top cover assembly;

[0035] 202-Top cover plate;

[0036] 202a - Explosion-proof port;

[0037] 204 - First terminal block;

[0038] 206 - Second terminal board;

[0039] 208 - Explosion-proof valve;

[0040] 2082 - Edge connection part;

[0041] 2084 - Central Exhaust Section;

[0042] 20842-Flat base;

[0043] 20844 - Elevated portion;

[0044] 20844a - Horizontal and vertical scratches;

[0045] 20844b - Branch notch;

[0046] 20846 - Transition Section;

[0047] 300-Electrode Assembly;

[0048] 302 - First electrode;

[0049] 304 - Second electrode;

[0050] 400 - Insulating film;

[0051] 500 - First collector;

[0052] 502 - First electrode connection part;

[0053] 600 - Second collector;

[0054] 602 - Second pole ear connection part.

[0055] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation

[0056] The present application will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0057] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when it is mentioned that one element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0058] Please refer to Figure 1 , Figure 1 An exploded view of a secondary battery is shown.

[0059] The secondary battery 1000 includes a housing 100, a secondary battery top cover assembly 200 (hereinafter referred to as the top cover assembly), an electrode assembly 300, and an insulating film 400. The electrode assembly 300 and the insulating film 400 are housed within the housing 100, with the electrode assembly 300 enclosed by the insulating film 400. The opening of the housing 100 can be sealed by the top cover assembly 200, and the contact portions of the top cover assembly 200 and the housing 100 can be connected to each other, for example, by welding.

[0060] The electrode assembly 300 is manufactured by winding or stacking and includes a first electrode, a second electrode, and a separator for separating the first electrode and the second electrode. Here, the first electrode can be used as a negative electrode and the second electrode can be used as a positive electrode, or vice versa.

[0061] Both the first electrode and the second electrode include a coated portion coated with active material and an uncoated portion uncoated with active material. Since the active materials coated on the first electrode and the second electrode are different, the first electrode and the second electrode can have different polarities.

[0062] For example, the first electrode is a positive electrode, and the active material coated on the positive electrode can be lithium iron phosphate, lithium cobalt oxide, or lithium manganese oxide, etc. The second electrode is a negative electrode, and the active material coated on the negative electrode can be carbon or silicon. The uncoated portion of the first electrode forms the first tab 302, and the uncoated portion of the second electrode forms the second tab 304.

[0063] The secondary battery also includes a first current collector 500 and a second current collector 600. The first electrode and the second electrode of the electrode assembly 300 can be connected to the first current collector 500 and the second current collector 600, respectively. The first current collector 500 is made of conductive material and is connected to a first tab 302 located at one end of the electrode assembly 300 so as to connect with the first electrode.

[0064] The first current collector 500 includes a first terminal connection portion and a first electrode connection portion 502. The first electrode connection portion 502 is connected to a first electrode tab 302, and the first terminal connection portion is connected to a first electrode terminal (not shown in the figures) of the top cover assembly 200. A connection hole is provided on the first terminal connection portion, and the first electrode terminal is matched with the connection hole so as to accommodate the first electrode terminal in the connection hole. The first electrode terminal and the first terminal connection portion can be connected to each other, for example, by welding.

[0065] The second current collector 600 is made of conductive material and is connected to the second tab 304 located at one end of the electrode assembly 300 so as to connect to the second electrode plate.

[0066] The second current collector 600 includes a second terminal connection portion and a second electrode connection portion 602. The second electrode connection portion 602 is connected to a second electrode tab 304, and the second terminal connection portion is connected to a second electrode terminal (not shown in the figures) of the top cover assembly 200. A connection hole is provided on the second terminal connection portion, and the second electrode terminal is matched with the connection hole to be accommodated within the connection hole. The second electrode terminal and the second terminal connection portion can be connected to each other, for example, by soldering.

[0067] It should be noted that, Figure 1 Although the first tab 302 and the second tab 304 are shown extending from the side of the electrode assembly 300, the structure of the electrode assembly 300 is not limited to this.

[0068] Please refer to Figure 2 , Figure 2 A top view of the top cover assembly is shown.

[0069] The top cover assembly 200 includes a top cover plate 202, a first electrode terminal, and a second electrode terminal (not shown in the figures). The top cover plate 202 has terminal holes (not shown in the figures) to allow the first and second electrode terminals to extend outwards. For example, the portion of the first electrode terminal extending out of the top cover plate 202 is connected to a first terminal plate 204, and subsequently to an external conductive terminal.

[0070] A similar structure can also be applied to the second electrode terminal, that is, the portion of the second electrode terminal extending out of the top cover plate 202 is connected to the second terminal plate 206.

[0071] The top cover assembly 200 also includes an explosion-proof valve 208, which is connected to the top cover plate 202 and is located approximately in the center of the top cover plate 202.

[0072] Please refer to Figure 3 , Figure 3 An exploded view of the top cover assembly is shown.

[0073] The top cover plate 202 has an explosion-proof port 202a, which is sealed by an explosion-proof valve 208. For example, the explosion-proof port 202a is configured as an elongated oval opening. The shape of the explosion-proof valve 208 matches the shape of the explosion-proof port 202a. The explosion-proof valve 208 includes an edge connecting part 2082 and a central exhaust part 2084. The edge connecting part 2082 is sealed to the top cover plate 202 and connected to the periphery of the explosion-proof port 202a. The central exhaust part 2084 allows gas inside the housing 100 to be discharged after tearing.

[0074] In one exemplary embodiment, the thickness of the edge connecting portion 2082 can be greater than the thickness of the central exhaust portion 2084, so that a more reliable connection can be formed between the edge connecting portion 2082 and the top cover plate 202. The edge connecting portion 2082 is connected to the inner surface of the top cover plate 202, and the connection method can be welding, such as laser welding.

[0075] Please refer to Figure 4 , Figure 4 A top view of the explosion-proof valve is shown.

[0076] The central exhaust section 2084 includes a flat base 20842 and a raised portion 20844 protruding outward relative to the flat base 20842. The flat base 20842 has a flat surface, and the raised portion 20844 protrudes from the flat base 20842 toward the side away from the electrode assembly 300 (protruding toward the outside of the top cover assembly 200) to form a protruding structure.

[0077] The raised portion 20844 is provided with a horizontally shaped notch 20844a and a branch notch 20844b connected to the end of the horizontally shaped notch 20844a. The horizontally shaped notch 20844a extends along the length of the elongated oval explosion-proof valve 208, and the angle between the branch notch 20844b and the horizontally shaped notch 20844a is not zero. When the internal pressure inside the housing 100 is greater than a preset pressure (e.g., due to overcharging and excessive gas production), the horizontally shaped notch 20844a and the branch notch 20844b can be opened faster than other parts of the housing 100 to form a tear for gas to escape. This tear can quickly release the gas inside the housing 100 to relieve the internal pressure of the housing 100, thereby reducing the risk of secondary battery explosion.

[0078] Please refer to Figure 5 , Figure 5 A cross-sectional view of the explosion-proof valve is shown.

[0079] The raised portion 20844 bulges outward from the side away from the internal space of the housing 100 and is ridge-shaped. Both the horizontal and vertical notches 20844a and the branch notches 20844b are located at the top of the ridge-shaped peak. Since the raised portion 20844 forms a recess at a corresponding location on the inner surface after bulging, when there is sufficient internal pressure in the housing 100, the internal pressure of the housing 100 can be concentrated in the recess, i.e., at the top of the ridge-shaped peak. At this time, the horizontal and vertical notches 20844a and the branch notches 20844b located at the top of the raised portion 20844 can be rapidly torn apart under a preset pressure to instantaneously respond to the excessively increased gas pressure inside the housing 100.

[0080] Optional, please refer to Figure 6 The horizontal and vertical grooves 20844a and the branch grooves 20844b can also be provided on the inner surface of the raised portion 20844 facing the electrode assembly 300, that is, at the bottom of the recess. Similarly, under the action of the internal pressure of the housing 100, the gas accumulates in the recess and forms stress concentration at the horizontal and vertical grooves 20844a and the branch grooves 20844b. The gas is quickly ejected after tearing the horizontal and vertical grooves 20844a and the branch grooves 20844b.

[0081] It is known that the raised portion 20844 bulges outward relative to the flat base portion 20842, rather than bending towards the internal space of the housing 100. This arrangement is to avoid fatigue fracture caused by repeated expansion of the central exhaust portion 2084 under internal pressure, and to prevent the defect of reduced opening pressure of the explosion-proof valve 280.

[0082] Please continue to refer to this. Figure 4 In order to increase the area of ​​the tear formed at the horizontal and vertical notches 20844a and the branch notches 20844b, two branch notches 20844b can be set at the same end of the horizontal and vertical notches 20844a. In this way, the two branch notches 20844b and the one horizontal notch 20844a can form an approximately Y-shaped notch. The Y-shaped notch can increase the opening area after tearing, thereby increasing the flow rate when the gas is discharged.

[0083] Furthermore, in order to enable the explosion-proof valve 208 to be opened quickly, the two ends of the horizontal and vertical groove 20844a can be respectively set as Y-shaped grooves, that is, the two ends of the horizontal and vertical groove 20844a are connected to two branch grooves 20844b. After this setting, the two ends of the horizontal and vertical groove 20844a and the two branch grooves 20844b respectively form two intersections. The central exhaust part 2084 can be torn open from the two intersections first, and quickly form a tear that connects and penetrates the flat base 20842. At this time, the tear allows the gas to release the pressure inside the housing 100 with a larger exhaust volume.

[0084] Two branch marks 20844b located at the same end of the horizontal and vertical marks 20844a can be symmetrically arranged about the line containing the horizontal and vertical marks 20844a. This ensures that the lengths of each branch mark 20844b are equal, and the angles between them and the horizontal and vertical marks 20844a are also equal. Under the internal pressure of the housing 100, the intersection of the two branch marks 20844b and the horizontal and vertical marks 20844a becomes the starting point of the tear. From this tearing starting point, the central vent 2084 can be simultaneously torn along the two branch marks 20844b and one horizontal and vertical mark 20844a until the tear is completely opened, thereby shortening the gas release time within the housing 100 and improving the safety of the secondary battery.

[0085] According to an exemplary embodiment, the angle θ between each branch notch 20844b and the horizontal and vertical notches 20844a can be selected within the range of 120° to 150°. Analysis shows that within this range, when the tear extends along the three paths from the intersection of the three notches, the opening can remain synchronized when the three notches form approximately equal intervals. This is because when gas is rapidly ejected, the stress concentration point is the intersection of the three notches, which opens first, and the central exhaust section 2084 is torn open radially from this point. If the angles between the three notches are approximately equal, the gas impact force on each notch is essentially equal, and the three notches can be torn synchronously under the same gas impact force.

[0086] In an optional embodiment, the angle between each branch notch 20844b and the horizontal / vertical notch 20844a can be further selected within the range of 130° to 140°. In this case, the interval angles between the three notches are more equal, and when the central exhaust portion 2084 is torn at the notch, the tearing process of the branch notches 20844b and the horizontal / vertical notches 20844a will be faster and smoother, and the area of ​​the tear opening will be larger.

[0087] On the other hand, to improve the synchronization of tearing, this application further sets the length of the transverse groove 20844a to 1.5 to 2.5 times the length of the branch groove 20844b. The length of the transverse groove 20844a refers to the length of the transverse groove 20844a along its extension direction (e.g., ...). Figure 2 As shown, the extension direction of the horizontal score 20844a is parallel to the length direction of the top cover plate, and the length of the branch score 20844b refers to the length of the branch score 20844b along its extension direction (e.g., Figure 2 As shown, the extension direction of the branch notch 20844b is at a non-zero angle to the extension direction of the horizontal notch 20844a. For the scheme of setting branch notches 20844b at both ends of the horizontal notch 20844a, there is a possibility that the two tearing initiation points can be opened simultaneously. At each tearing initiation point, if the tear is made along three notches of approximately equal length, the three tearing paths are basically equal. Therefore, the time required for the two Y-shaped notches to tear is approximately equal, and they are torn almost simultaneously. This ensures that the explosion-proof valve 208 is fully opened in a shorter time.

[0088] In one alternative embodiment, the length of the horizontal serration 20844a can be further set to 1.8 to 2.2 times the length of the branch serration 20844b. This results in the three serrations intersecting at the same tear initiation point having closer lengths, leading to greater synchronicity when the two Y-shaped serrations open.

[0089] Please refer to this again. Figure 4 The central exhaust section 2084 also includes a transition section 20846, through which the raised portion 20844 is connected to the flat base portion 20842, and the transition section 20846 is inclined relative to the flat base portion 20842. The transition section 20846 allows the raised portion 20844 to gradually protrude relative to the flat base portion 20842 and form a gradually increasing ridge-like protrusion. At the same time, the transition section 20846 can also guide the gas inside the housing 100 to accumulate in the recess, and ultimately form stress concentration phenomena such as tearing horizontal and vertical scratches 20844a and branch scratches 20844b in the recess.

[0090] In one exemplary embodiment, the tilt angle α of the transition portion 20846 can be set to 2° to 15° (see [reference]). Figure 6 The explosion-proof valve 208 is manufactured by stamping. The transition part 20846 can provide assistance for the raised part 20844 to protrude at a preset height relative to the flat base part 20842. At the same time, the setting of the transition part 20846 can improve the processability of the raised part 20844 and prevent the raised part 20844 from protruding too high, which would cause the central exhaust part 2084 to break.

[0091] Optionally, the tilt angle α of the transition section 20846 can be further set to 3° to 6°.

[0092] This application also provides a vehicle that includes the secondary battery in any of the above embodiments.

[0093] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A secondary battery, characterized in that, include: Electrode assembly; The shell has an opening; And a secondary battery top cover assembly, the secondary battery top cover assembly including a top cover sheet and an explosion-proof valve connected to the top cover sheet; the secondary battery top cover assembly is connected to the opening of the housing and forms an encapsulation space, and the electrode assembly is encapsulated in the encapsulation space; The explosion-proof valve includes a flat base and a raised portion protruding outward relative to the flat base. The raised portion is provided with a horizontal and vertical groove and a branch groove connected to one end of the horizontal and vertical groove. The horizontal and vertical groove and the branch groove form a non-zero angle. The raised portion protrudes away from the electrode assembly, and the flat base portion is closer to the electrode assembly of the secondary battery than the raised portion. The raised portion has a ridge-shaped sharp angle, and the inner surface of the explosion-proof valve opposite to the raised portion has a recessed portion corresponding to the shape of the raised portion; Both the horizontal and vertical grooves and the branching grooves are located at the top of the ridge-like sharp corner, and / or Both the horizontal and vertical grooves and the branch grooves are located at the bottom of the recessed portion, corresponding to the ridge-shaped sharp corner.

2. The secondary battery according to claim 1, characterized in that, There are two branch marks, and the horizontal and vertical marks and the two branch marks form a Y shape.

3. The secondary battery according to claim 2, characterized in that, The two branch marks are symmetrical with respect to the horizontal and vertical marks, and both ends of the horizontal and vertical marks are connected to the two branch marks.

4. The secondary battery according to claim 1, characterized in that, The angle between the branch marks and the horizontal and vertical marks is 120°~150°.

5. The secondary battery according to claim 1, characterized in that, The length of the horizontal and vertical grooves is 1.5 to 2.5 times the length of the branch grooves.

6. The secondary battery according to any one of claims 1-5, characterized in that, The explosion-proof valve also includes a transition section, the raised portion is connected to the flat base portion via the transition section, and the transition section is inclined relative to the flat base portion.

7. The secondary battery according to claim 6, characterized in that, The inclination angle of the transition section is 2°~15°.

8. A car, characterized in that, Includes the secondary battery as described in any one of claims 1-7.

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