Battery top cover and battery

Abstract

This application relates to the field of secondary battery technology, and provides a battery top cover and a battery. The battery top cover includes a top cover sheet and a composite film structure. The top cover sheet has an injection hole and a replenishment hole, the replenishment hole being used for secondary electrolyte injection after the initial injection; the composite film structure is used to seal the replenishment hole and is located on the side of the top cover sheet facing the secondary battery. The battery top cover provided by this application, while maintaining good sealing performance, facilitates secondary electrolyte injection to maintain sufficient electrolyte, thereby extending battery cycle life and reducing the risk of battery thermal runaway.

Description

Technical Field

[0001] This application relates to the field of secondary battery technology, and in particular to a battery top cover and a battery. Background Technology

[0002] As the medium for lithium-ion transport in secondary batteries, the electrolyte's content directly affects battery performance and plays a crucial role in cycle life. Sufficient electrolyte content provides a favorable environment for lithium-ion transport, effectively reducing internal battery losses, significantly extending battery life, and thus improving overall battery performance and economic efficiency. However, as the number of battery cycles increases, the electrolyte will gradually dry out. Utility Model Content

[0003] The gradual drying of the electrolyte hinders the insertion, extraction, and migration of lithium ions. If sufficient electrolyte is not replenished before it dries out, the battery's cycle life will be significantly shortened, and it may even lead to thermal runaway. Therefore, it is necessary to provide a battery top cover that, while maintaining good sealing, facilitates secondary electrolyte injection to ensure sufficient electrolyte levels, thereby extending battery cycle life and reducing the risk of thermal runaway.

[0004] A battery top cover includes a top cover sheet and a composite film layer structure. The top cover sheet is provided with an injection hole and a replenishment hole. The replenishment hole is used for secondary injection after the initial injection. The composite film layer structure is used to seal the replenishment hole and is located on the side of the top cover sheet facing the secondary battery.

[0005] It is understood that the injection port can be used for the initial electrolyte filling of the battery, and the replenishment port can be used for secondary electrolyte filling after the initial filling to replenish the electrolyte in the battery. Together with the composite film structure at the replenishment port, it ensures that the initially injected electrolyte will not leak through the replenishment port. Since the composite film structure is located on the side of the top cover facing the secondary battery, i.e., inside the battery, it avoids the risk of damage due to exposure to the outside of the battery, further maintaining the sealing of the replenishment port. In other words, it is precisely the combination of the replenishment port and the composite film structure that alleviates the problem of electrolyte gradually drying out after multiple cycles, ensuring sufficient electrolyte for lithium-ion insertion / extraction and migration, thus greatly extending the battery's cycle life and reducing the risk of battery thermal runaway.

[0006] In some embodiments, the composite film structure includes at least one adhesive layer and at least one metal layer, wherein the adhesive layer and the metal layer are stacked.

[0007] In some embodiments, the position adjacent to the liquid replenishment hole in the composite film structure is set as the metal layer and defined as the first metal layer, and the adhesive layer adjacent to the first metal layer is defined as the first adhesive layer; the projection of the first adhesive layer along the axial direction of the liquid replenishment hole is greater than the projection of the first metal layer along the axial direction of the liquid replenishment hole.

[0008] In some embodiments, the projection of the first metal layer along the axial direction of the fluid replenishment hole is greater than the projection of the fluid replenishment hole along the axial direction of the fluid replenishment hole.

[0009] In some embodiments, the first adhesive layer has a recess on the side facing the first metal layer, the projection of the recess along the axial direction of the fluid replenishment hole is smaller than the projection of the first adhesive layer, the first metal layer is at least partially accommodated in the recess, and the first adhesive layer is bonded and fixed to the top cover sheet on the periphery of the recess.

[0010] In some embodiments, the first metal layer is flush with the side of the top cover facing the top cover, as is the side of the recess facing the top cover.

[0011] In some embodiments, the fluid replenishment hole, the adhesive layer, and the metal layer are all circular, the diameter of the fluid replenishment hole is D1, and the diameter of the first adhesive layer is D3;

[0012] The metal layers other than the first metal layer are stacked metal layers, and the diameter of the stacked metal layer is D4, then D4 satisfies: D1≤D4≤D3; and / or, the adhesive layers other than the first adhesive layer are stacked adhesive layers, and the diameter of the stacked adhesive layer is D5, then D5 satisfies: D1≤D5≤D3.

[0013] In some embodiments, the side of the liquid replenishment hole facing the secondary battery is provided with an assembly step, and the side of the assembly step facing the secondary battery is recessed towards the side of the top cover sheet opposite to the secondary battery, and the composite film structure is at least partially accommodated within the assembly step.

[0014] In some embodiments, the liquid replenishment hole has a conical surface on the side of the assembly step away from the secondary battery, and the diameter of the conical surface gradually increases from the inside to the outside of the battery along the axial direction of the liquid replenishment hole; along the axial direction of the liquid replenishment hole, the projection of the composite film structure is greater than the projection at the minimum diameter of the conical surface.

[0015] This application also provides a battery, including a battery casing and the aforementioned battery top cover, wherein the battery top cover is connected to the battery casing. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a battery top cover provided in one embodiment of this application;

[0018] Figure 2 A partial cross-sectional view of the top cover sheet in a battery top cover provided in an embodiment of this application;

[0019] Figure 3 A partial cross-sectional view of a battery top cover provided in an embodiment of this application;

[0020] Figure 4 This is a cross-sectional view of the composite film structure in the battery top cover provided in an embodiment of this application;

[0021] Figure 5 A cross-sectional view of the composite film structure in the battery top cover provided in another embodiment of this application;

[0022] Figure 6 A cross-sectional view of the composite film structure in the battery top cover provided in another embodiment of this application;

[0023] Figure 7 A partial cross-sectional view of the battery top cover at the liquid filling hole, provided in another embodiment of this application;

[0024] Figure 8 This is a partial cross-sectional view of a battery top cover provided in another embodiment of this application.

[0025] Reference numerals: 100, Battery top cover; 110, Top cover sheet; 111, Injection hole; 112, Replenishment hole; 120, Composite film structure; 121, Metal layer; 122, Adhesive layer; 130, First sealing structure; 131, First sealing nail; 132, First protective layer; 140, Second sealing structure; 141, Second sealing nail; 142, Second protective layer; 150, Terminal post; 1121, Assembly step; 1122, Step surface; 1123, Conical surface; 1211, First metal layer; 1212, Stacked metal layer; 1220, Recess; 1221, First adhesive layer; 1222, Stacked adhesive layer. Detailed Implementation

[0026] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0027] It should be noted that when a component is referred to as being "fixed to" or "attached to" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application's specification are for illustrative purposes only and do not represent the only possible implementation.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0029] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0030] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items.

[0031] Please see Figures 1 to 3One embodiment of this application provides a battery top cover 100, which can be packaged and fitted with a battery casing. A secondary battery is installed within an assembly cavity jointly enclosed by the battery top cover 100 and the battery casing. The battery top cover 100 includes a top cover sheet 110 and a composite film structure 120. The top cover sheet 110 has an injection hole 111 and a replenishment hole 112, the replenishment hole 112 being used for secondary replenishment after the initial replenishment. The composite film structure 120 is used to seal the replenishment hole 112 and is located on the side of the top cover sheet 110 facing the secondary battery.

[0032] Understandably, the injection hole 111 can be used for the initial electrolyte filling of the battery, and is subsequently sealed to maintain its sealing performance. The sealing method for the injection hole 111 will be described later. Simultaneously, by providing the replenishment hole 112, a secondary electrolyte filling can be performed on the battery after the initial filling to replenish the electrolyte within the battery. The composite membrane structure 120, in conjunction with this, seals the replenishment hole 112, ensuring that electrolyte does not leak through it during or after the initial filling. In other words, when the battery top cover 100 is sealed to the battery casing, during the initial electrolyte filling of the secondary battery through the injection hole 111, the composite membrane structure 120 remains sealed at the replenishment hole 112 to maintain its sealing performance. When the battery has undergone multiple cycles and requires electrolyte replenishment, secondary replenishment can be performed through the replenishment hole 112. Furthermore, because the composite membrane structure 120 is located on the side of the top cover 110 facing the secondary battery, that is, the composite membrane structure 120 is located inside the battery, the risk of it being easily damaged due to being exposed to the outside of the battery is avoided, and the sealing of the liquid replenishment hole 112 is further maintained.

[0033] In summary, the battery top cover 100 provided in this application, by utilizing the combination of the liquid replenishment hole 112 on the top cover plate 110 and the composite film structure 120, not only ensures good sealing at the liquid replenishment hole 112, but also facilitates secondary liquid injection into the secondary battery, thereby alleviating the problem of the electrolyte gradually drying out after multiple cycles of use, ensuring that there is enough electrolyte in the secondary battery for lithium ion insertion / extraction and migration, greatly extending the cycle life of the battery, and reducing the risk of battery thermal runaway.

[0034] Please continue reading. Figures 1 to 3 Taking a rectangular top cover 110 as an example, the length direction of the top cover 110 is the X-axis direction, the width direction is the Y-axis direction, and the thickness direction is the Z-axis direction. The replenishment hole 112 and the injection hole 111 can be arranged at intervals along the X-axis direction. Simultaneously, both the injection hole 111 and the replenishment hole 112 are arranged through the top cover 110 along its thickness direction; therefore, the axial direction of both the injection hole 111 and the replenishment hole 112 is along the Z-axis direction.

[0035] Please see Figure 3 , Figure 4 and Figure 6 In some embodiments, the composite membrane structure 120 includes at least one adhesive layer 122 and at least one metal layer 121, with the adhesive layer 122 and the metal layer 121 stacked together. The metal layer 121 and the adhesive layer 122 are stacked along the Z-axis of the liquid replenishment hole to ensure that the overall thickness of the composite membrane structure 120 is relatively thin, which facilitates puncture and secondary liquid injection while maintaining the sealing performance.

[0036] Understandably, by utilizing the adhesive properties of the adhesive layer 122, the composite membrane structure 120 can be firmly bonded to the top cover plate 110, ensuring the reliability of the connection between the two. Furthermore, when multiple metal layers 121 are used, any two adjacent metal layers 121 are bonded and fixed together by the adhesive layer 122, forming a structure in which the metal layers 121 and the adhesive layer 122 are staggered and stacked, thereby maintaining the high strength of the composite membrane structure 120 and improving the sealing effect on the liquid replenishment hole 112.

[0037] In other words, the metal layer 121 meets the strength requirements of the composite film structure 120, and the adhesive layer 122 not only satisfies the assembly requirements between the composite film structure 120 and the top cover 110, but also ensures the bonding between the multiple metal layers 121. Furthermore, the adhesive layer 122 can also improve the overall strength of the composite film structure 120, making it more resistant to puncture during secondary liquid injection. The adhesive layer 122 is made of a flexible material, and its hardness is significantly lower than that of the metal layer 121.

[0038] like Figure 4 As shown, in some specific embodiments, the composite membrane structure 120 includes an adhesive layer 122 and a metal layer 121, which are stacked along the Z-axis of the liquid replenishment hole. The adhesive layer 122 bonds the metal layer 121 to the top cover plate 110, thereby achieving a fixed assembly of the composite membrane structure 120 and the top cover plate 110.

[0039] like Figure 5 As shown, alternatively, the composite membrane structure 120 includes an adhesive layer 122 and two metal layers 121, which are stacked and staggered along the Z-axis of the liquid replenishment hole. The adhesive layer 122 is disposed between the two metal layers 121 to satisfy the bonding and fixing of the two metal layers 121. One of the metal layers 121 is welded and fixed to the top cover plate 110; or, the projection of the adhesive layer 122 is larger than the projection of the metal layer 121 to bond and fix it to the top cover plate 110. This is only an example for illustration.

[0040] Alternatively, the composite membrane structure 120 may include two adhesive layers 122 and a metal layer 121, with the metal layer 121 disposed between the two adhesive layers 122, and one adhesive layer 122 being bonded and fixed to the top cover sheet 110.

[0041] like Figure 6 As shown, in another alternative embodiment, the composite membrane structure 120 includes two adhesive layers 122 and two metal layers 121, which are stacked and staggered along the Z-axis of the liquid replenishment hole. These four can form a stacked structure of "metal layer 121 - adhesive layer 122 - metal layer 121 - adhesive layer 122". In this case, the first metal layer 121 can be welded to the top cover plate 110, or the last adhesive layer 122 can be bonded to the top cover plate 110, as long as it can satisfy the fixed assembly of the composite membrane structure 120 and the top cover plate 110.

[0042] Of course, the number of metal layers 121 and adhesive layers 122 can also be three, four, etc., as long as the overall thickness of the composite membrane structure 120 is easily punctured and the seal of the liquid replenishment hole 112 is maintained. This is just an example.

[0043] It should be added that the number of metal layer 121 and adhesive layer 122 should not be too many. If there are too many, the overall thickness of the composite film structure 120 will be too thick, which will make it difficult to puncture the composite film structure 120.

[0044] Please see Figures 4 to 6 In some embodiments, the thickness T1 of the adhesive layer 122 ranges from 50 μm ≤ T1 ≤ 200 μm. Since the adhesive layer 122 needs to function as both a sealant and a bonding agent, its minimum thickness should not be too small, otherwise the bonding effect will be weakened. Of course, the maximum thickness of the adhesive layer 122 should also not be too large. If it is too large, not only will some of the adhesive layer 122 protrude during press bonding, but the metal layer 121 will also be insufficient to support the overall strength while maintaining the uniform thickness of the composite film structure 120.

[0045] Furthermore, the thickness T2 of the metal layer 121 is in the range of 15μm ≤ T1 ≤ 300μm. Since the metal layer 121, in addition to satisfying the sealing requirements, also needs to improve the strength of the composite membrane structure 120, the maximum thickness of the metal layer 121 should not be too small, otherwise it will lead to poor overall structural strength and weaken the sealing effect. Of course, the thickness of the metal layer 121 should also not be too large, otherwise it will be difficult to puncture.

[0046] Therefore, the thickness of the adhesive layer 122 and the metal layer 121 needs to be limited to balance sealing and strength while facilitating the break-in operation for secondary injection.

[0047] The minimum thickness of the adhesive layer 122 is greater than the minimum thickness of the metal layer 121, and in particular, the thickness of the first adhesive layer 1221 is greater than the thickness of the first metal layer 1211. This ensures high bonding reliability while utilizing the recess 1220 to mate with the first metal layer 1211. The metal layer 121 adjacent to the liquid replenishment hole 112 is defined as the first metal layer 1211, and the adhesive layer 122 adjacent to the first metal layer 1211 is also defined as the first adhesive layer 1221.

[0048] In some specific embodiments, the thickness T1 of the adhesive layer 122 can be 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, or 200 μm, etc. Meanwhile, the thickness T2 of the metal layer 121 can be 15 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, or 300 μm, etc. Of course, the thicknesses of the adhesive layer 122 and the metal layer 121 can also be the same, provided they meet the aforementioned respective ranges. This is merely an example.

[0049] Furthermore, the thickness T1 of the adhesive layer 122 ranges from 70μm to 100μm. The thickness T2 of the metal layer 121 ranges from 40μm to 100μm. This configuration further ensures sealing and strength while facilitating the break-in operation for secondary liquid injection. For example, the thickness T1 of the adhesive layer 122 can be 70μm, 80μm, 90μm, or 100μm, and the thickness T2 of the metal layer 121 can be 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, or 100μm, etc.

[0050] like Figure 3 As shown, in some embodiments, the adhesive layer 122 is made of polypropylene. Polypropylene has good chemical resistance, so when the composite film structure 120 is located on the top cover 110 facing the secondary battery, it can improve the corrosion resistance of the composite film structure 120. Simultaneously, polypropylene has high impact resistance, which can buffer impacts and ensure that the battery maintains the seal at the electrolyte filling hole 112 even when subjected to impact, mitigating leakage problems caused by impact. Furthermore, polypropylene also has certain high-temperature resistance and thermal stability, ensuring the reliable operation of the battery under high-temperature conditions.

[0051] Furthermore, the metal layer 121 is made of aluminum, stainless steel, or chromium. That is, the metal layer 121 can be made of a metal material with good corrosion resistance, strength, and toughness. Thus, when it is located on the top cover 110 facing the secondary battery, it can alleviate the problem of corrosion by the electrolyte; and this arrangement, on the one hand, maintains the high strength of the composite film structure 120, ensuring the seal at the electrolyte filling hole 112 when the battery is impacted, and on the other hand, facilitates puncture by hard tools, making it easy to create a puncture point for secondary electrolyte injection.

[0052] Please see Figure 3 In some embodiments, a metal layer 121 is positioned adjacent to the liquid replenishment hole 112 in the composite membrane structure 120. That is, the metal layer 121 covers the side of the liquid replenishment hole 112 facing the secondary battery. This arrangement ensures the strength of the composite membrane structure 120 on the side away from the secondary battery; on the other hand, the metal layer 121 has no adhesive effect, so dust, impurities, etc. will not adhere to the composite membrane structure 120, making it easier to clean and prevent damage.

[0053] Alternatively, the adhesive layer 122 can be positioned adjacent to the liquid replenishment hole 112, in which case the adhesive layer 122 is directly bonded to the top cover plate 110 located at the edge of the liquid replenishment hole 112.

[0054] Please see Figure 3 , Figure 5 and Figure 6 In some embodiments, the metal layer 121 adjacent to the replenishment hole 112 is defined as the first metal layer 1211, and the adhesive layer 122 adjacent to the first metal layer 1211 is defined as the first adhesive layer 1221. The projection of the first adhesive layer 1221 along the Z-axis of the replenishment hole is greater than the projection of the first metal layer 1211 along the Z-axis of the replenishment hole. That is, along the Z-axis of the replenishment hole, the projection of the first metal layer 1211 is located within the projection of the first adhesive layer 1221, and the projection portion of the first adhesive layer 1221 protrudes beyond the projection of the first metal layer 1211. The portion of the first adhesive layer 1221 protruding beyond the first metal layer 1211 can be bonded and fixed to the top cover plate 110, thereby satisfying the fixation of the composite film structure 120 and the top cover plate 110. In some embodiments, the portion of the first adhesive layer 1221 protruding from the first metal layer 1211 is annular, that is, the adhesive surface on the first adhesive layer 1221 for bonding and fixing with the top cover sheet 110 is arranged in annular shape, and the adhesive surface surrounds the outer periphery of the first metal layer 1211.

[0055] Furthermore, the projection of the first metal layer 1211 along the Z-axis of the replenishment hole is greater than the projection of the replenishment hole 112 along the Z-axis of the replenishment hole. This arrangement ensures that the first metal layer 1211 can completely cover the replenishment hole 112, ensuring that the first adhesive layer 1221 is not exposed within the projection of the replenishment hole 112, further reducing dust, impurities, etc. adhering to the composite film structure 120.

[0056] Please continue reading. Figure 3 , Figure 5 and Figure 6 In some embodiments, the first adhesive layer 1221 has a recess 1220 on the side facing the first metal layer 1211. The projection of the recess 1220 along the Z-axis of the fluid replenishment hole is smaller than the projection of the first adhesive layer 1221. The first metal layer 1211 is at least partially accommodated within the recess 1220. The first adhesive layer 1221 is bonded and fixed to the top cover plate 110 on the periphery of the recess 1220.

[0057] On the one hand, the cooperation between the recess 1220 and the first metal layer 1211 increases the contact area between the first metal layer 1211 and the first adhesive layer 1221, thereby improving the reliability of their connection. On the other hand, the recess 1220's accommodation of the first metal layer 1211 helps maintain the flatness of the composite film structure 120 surface, which is more conducive to the bonding and pressing of the first adhesive layer 1221 with the top cover plate 110, reducing the bonding resistance of the first adhesive layer 1221, improving the reliability of the connection with the top cover plate 110, and thus enhancing the sealing effect. In addition, the cooperation between the recess 1220 and the first metal layer 1211 limits the assembly of the first metal layer 1211, alleviating the problem of the first metal layer 1211 shifting due to extrusion pressure, ensuring that the first metal layer 1211 is aligned with and sealed against the liquid replenishment hole 112, further maintaining a high sealing effect.

[0058] Furthermore, the side of the first metal layer 1211 facing the top cover plate 110 is flush with the side of the recess 1220 facing the top cover plate 110. That is, the thickness of the first metal layer 1211 is the same as the depth of the recess 1220, and the first metal layer 1211 is completely placed within the recess 1220 to ensure that the side of the composite film structure 120 facing the top cover plate 110 is flat, further improving the bonding reliability between the first adhesive layer 1221 and the top cover plate 110 and maintaining a high level of sealing.

[0059] Please see Figure 3 , Figure 6 and Figure 7In some embodiments, at least one of the metal layer 121 and the adhesive layer 122 is provided with at least two layers. For example, the composite film structure 120 includes at least two metal layers 121 and at least one adhesive layer 122, or the composite film structure 120 includes at least two metal layers 121 and at least two adhesive layers 122. In this case, the metal layer 121 other than the first metal layer 1211 is a stacked metal layer 1212, and the adhesive layer 122 other than the first adhesive layer 1221 is a stacked adhesive layer 1222.

[0060] In some specific embodiments, the projection of the composite film structure 120 along the Z-axis of the liquid replenishment hole is circular, that is, the cross-section of the composite film structure 120 is circular. The liquid replenishment hole 112 is circular, with a diameter of D1, and the diameter of the first adhesive layer 1221 is D3. The diameter of the laminated metal layer 1212 is D4, therefore: D1≤D4≤D3. That is, the diameter of the laminated metal layer 1212 is greater than or equal to the diameter of the liquid replenishment hole 112, and less than or equal to the diameter of the first adhesive layer 1221. In other words, the diameter of the laminated metal layer 1212 is not less than the diameter of the liquid replenishment hole 112, and not greater than the diameter of the first adhesive layer 1221.

[0061] In other words, the above-described configuration ensures that each metal layer 121 completely covers the electrolyte filling hole 112, thereby improving the overall structural strength. Furthermore, each metal layer 121 does not protrude beyond the first adhesive layer 1221, reducing interference with other structures and minimizing the risk of the metal layer 121 bearing the impact before the adhesive layer 122 during battery impact. This further enhances the sealing effect at the electrolyte filling hole 112.

[0062] Furthermore, if the diameter of the laminated adhesive layer 1222 is D5, then D5 satisfies: D1 ≤ D5 ≤ D3. That is, the diameter of the laminated adhesive layer 1222 is greater than or equal to the diameter of the fluid replenishment hole 112, and less than or equal to the diameter of the first adhesive layer 1221. In other words, the diameter of the laminated adhesive layer 1222 is not less than the diameter of the fluid replenishment hole 112, and not greater than the diameter of the first adhesive layer 1221.

[0063] This design ensures that each adhesive layer 122 completely covers the liquid replenishment hole 112, and that the overall cross-section of the composite membrane structure 120 is larger than the cross-section of the liquid replenishment hole 112, thereby improving strength and sealing performance. Furthermore, the laminated adhesive layers 1222 do not protrude beyond the first adhesive layer 1221, reducing interference with other structures and thus minimizing impact on the sealing effect, further enhancing the sealing performance.

[0064] Please continue reading. Figure 3 , Figure 6 and Figure 7In some embodiments, the diameter of the first metal layer 1211 is D2, and D1 and D2 satisfy: 2mm ≤ (D2-D1) / 2 ≤ 10mm. The diameter of the first metal layer 1211 is larger than the aperture of the replenishment hole 112 to ensure complete coverage of the replenishment hole 112. Half of the difference between the diameter of the first metal layer 1211 and the aperture of the replenishment hole 112 is between 2mm and 10mm, which means that after the first metal layer 1211 covers the replenishment hole 112, the width of the radially outward protrusion of the first metal layer 1211 relative to the replenishment hole 112 is between 2mm and 10mm. By limiting the relationship between the diameter of the first metal layer 1211 and the aperture of the replenishment hole 112, it is ensured that the first metal layer 1211 fully covers the replenishment hole 112, while the width of the radially outward protrusion of the first metal layer 1211 is not excessive. In some specific embodiments, the width of the radially outward protrusion of the first metal layer 1211 relative to the liquid replenishment hole 112 can be 2mm, 4mm, 5mm, 6mm, 8mm or 10mm, etc.

[0065] Furthermore, the aperture D1 of the fluid replenishment hole 112 and the diameter D2 of the first metal layer 1211 satisfy the following condition: 4 mm ≤ (D2-D1) / 2 ≤ 7 mm. That is, the width of the radially outward protrusion of the first metal layer 1211 relative to the fluid replenishment hole 112 is between 4 mm and 7 mm. Understandably, the width of the protrusion of the first metal layer 1211 relative to the fluid replenishment hole 112 should not be too large or too small. If it is too large, the diameter of the first metal layer 1211 will be too large, which will not only easily cause assembly interference, but also reduce the contact area between the first adhesive layer 1221 and the top cover plate 110 when the dimensions of the first adhesive layer 1221 are consistent, affecting the bonding reliability between the composite film structure 120 and the top cover plate 110. Conversely, if it is too small, the coverage area of ​​the first metal layer 1211 relative to the fluid replenishment hole 112 will be small, weakening the overall strength of the composite film structure 120 and hindering sealing. In some specific embodiments, the width of the radially outward protrusion of the first metal layer 1211 relative to the liquid replenishment hole 112 can be 4mm, 5mm, 6mm or 7mm.

[0066] Please continue reading. Figure 3 , Figure 6 and Figure 7In some embodiments, the diameter D2 of the first metal layer 1211 and the diameter D3 of the first adhesive layer 1221 satisfy: 2mm ≤ (D3-D2) / 2 ≤ 10mm. The diameter of the first adhesive layer 1221 is larger than the diameter of the first metal layer 1211 to ensure that, in addition to forming the recess 1220, the first adhesive layer 1221 has sufficient area to bond and fix to the top cover plate 110. Therefore, half of the diameter difference between the first adhesive layer 1221 and the first metal layer 1211 is between 2mm and 10mm, which is equivalent to the width of the annular adhesive surface on the first adhesive layer 1221 along the radial direction of the liquid replenishment hole 112 being between 2mm and 10mm. This ensures that the first adhesive layer 1221 and the top cover plate 110 have sufficient contact area, improving connection reliability and thus ensuring good sealing.

[0067] Furthermore, the diameter D2 of the first metal layer 1211 and the diameter D3 of the first adhesive layer 1221 satisfy the following condition: 5mm ≤ (D3-D2) / 2 ≤ 7mm. That is, the width of the annular adhesive surface on the first adhesive layer 1221 along the radial direction of the liquid injection hole 112 is between 5mm and 7mm. Understandably, the width of the annular adhesive surface should not be too large or too small. If it is too large, the first adhesive layer 1221 will occupy too much of the size of the top cover plate 110, which may block the liquid injection hole 111 on the top cover plate 110 or interfere with other structures. Conversely, if it is too small, the contact area between the first adhesive layer 1221 and the top cover plate 110 will be too small, affecting the bonding strength. In some specific embodiments, the width of the annular adhesive surface on the first adhesive layer 1221 along the radial direction of the liquid replenishment hole 112 is 5mm, 5.5mm, 6mm, 6.2mm, 6.5mm, 6.8mm or 7mm, etc.

[0068] Alternatively, the projection of the composite membrane structure 120 along the Z-axis of the liquid replenishment hole can also be square, rectangular, etc. The projection shapes of the metal layer 121 and the adhesive layer 122 in the composite membrane structure 120 are the same, as long as they can be adapted to the shape of the liquid replenishment hole 112 to ensure sealing.

[0069] Please see Figure 2 , Figure 3 and Figure 7In some embodiments, the side of the replenishment hole 112 facing the secondary battery has an assembly step 1121. The side of the assembly step 1121 facing the secondary battery is recessed towards the side of the top cover plate 110 opposite to the secondary battery. The composite film structure 120 is at least partially accommodated within the assembly step 1121. That is, by utilizing the assembly step 1121 at the replenishment hole 112, the composite film structure 120 is accommodated, reducing the amount of the composite film structure 120 protruding relative to the top cover plate 110 towards the secondary battery, thereby reducing interference with other structures and ensuring the assembly reliability of the composite film structure 120 itself. Specifically, the composite film structure 120 can be entirely accommodated within the assembly step 1121, meaning the recess depth of the assembly step 1121 relative to the top cover plate 110 is greater than or equal to the thickness of the composite film structure 120, ensuring that the composite film structure 120 does not protrude from the assembly step 1121 and is not directly touched by other structures.

[0070] Alternatively, a portion of the composite membrane structure 120 may be housed within the assembly step 1121, in which case the thickness of the portion housed within the assembly step 1121 is greater than the thickness of the portion protruding from the assembly step 1121.

[0071] The recessed bottom of the assembly step 1121 is a step surface 1122, and the composite film structure 120 is pressed and bonded to the step surface 1122. That is, the composite film structure 120 contacts and is bonded to the step surface 1122 of the assembly step 1121 through its annular bonding surface located on the outer periphery of the first metal layer 1211, thereby improving the connection reliability and facilitating the bonding operation.

[0072] Alternatively, when the diameter of the first metal layer 1211 is substantially the same as the diameter of the first adhesive layer 1221, the first metal layer 1211 can be pressed into contact with the step surface 1122 and then welded to fix it.

[0073] Please continue reading. Figure 2 , Figure 3 and Figure 7 In some embodiments, the replenishment hole 112 has a conical surface 1123 on the side of the assembly step 1121 facing away from the secondary battery. The diameter of the conical surface 1123 gradually increases from the inside to the outside of the battery along the axial direction Z of the replenishment hole. Along the axial direction of the injection hole 111, the projection of the composite film structure 120 is greater than the projection at the minimum diameter of the conical surface 1123.

[0074] Understandably, the conical surface 1123 guides the insertion of the injection tool relative to the replenishment hole 112 during injection, facilitating the tool's smooth insertion into the injection hole 111 and piercing the composite membrane structure 120. Simultaneously, by ensuring complete coverage and fit between the composite membrane structure 120 and the minimum diameter of the conical surface 1123, the dimensions of the composite membrane structure 120 and its mating assembly step 1121 are constrained. In particular, the cross-sectional dimensions of the assembly step 1121 are crucial; if it is too large, it may affect the structural strength of the top cover plate 110, especially at the replenishment hole 112. Therefore, this design ensures reliable assembly between the composite membrane structure 120 and the top cover plate 110 while maintaining the required strength of the top cover plate 110 itself.

[0075] Please see Figure 8 In some embodiments, the battery top cover 100 further includes a first sealing structure 130, which is used to seal the replenishment hole 112 after secondary liquid injection. That is, after the secondary liquid injection of the secondary battery is completed through the replenishment hole 112, the first sealing structure 130 can be used to reseal the replenishment hole 112 to ensure the sealing performance of the replenishment hole 112 after secondary liquid injection. For example, the first sealing structure 130 includes a first sealing nail 131 and a first protective layer 132. Specifically, after secondary liquid injection, the first sealing nail 131 is driven into the replenishment hole 112, and then the first protective layer 132 is fixed to the side of the first sealing nail 131 facing away from the secondary battery along the Z-axis of the replenishment hole. The first protective layer 132 can be bonded to the top cover plate 110 or welded to the top cover plate 110, as long as it can meet the requirements for fixing and assembling the first protective layer 132; this is only an example.

[0076] In practical use, the battery top cover 100 also includes a second sealing structure 140, which is used to seal the injection hole 111 after liquid injection to maintain the sealing of the injection hole 111. The second sealing structure 140 includes a second sealing nail 141 and a second protective layer 142. After the second sealing nail 141 is driven into the injection hole 111, the second protective layer 142 is welded to the side of the injection hole 111 away from the secondary battery.

[0077] Alternatively, the second sealing structure 140 can also employ a composite membrane structure, which is welded or bonded to the side of the top cover 110 facing away from the secondary battery to seal the injection hole 111. In this case, the injection hole 111 can also serve as a secondary electrolyte replenishment point. For example, when electrolyte replenishment is required, the composite membrane structure at the injection hole 111 can be punctured using an injection needle. After secondary electrolyte replenishment is completed, the injection hole 111 is sealed using sealing nails. This is merely an example.

[0078] It should be added that using sealing glue nails to seal the injection hole 111 is a mature existing technology. The sealing glue nails and the filling hole 112 are similarly sealed, and the specific operation method will not be described in detail here.

[0079] like Figure 8 As shown, in actual use, after the user punctures the composite membrane structure 120 with an injection tool for secondary injection, the first sealing nail 131 in the first sealing structure 130 is driven into the replenishment hole 112. The corresponding first protective layer 132 is accommodated in the part of the replenishment hole 112 away from the secondary battery and is welded and fixed to the top cover plate 110. The first protective layer 132 is flush with the side of the top cover plate 110 away from the secondary battery to avoid problems such as the first protective layer 132 being easily touched due to protrusion.

[0080] The outer peripheral surface of the first protective layer 132 is adapted to the conical surface 1123 of the liquid replenishment hole 112. The pressing fit of the two conical surfaces further improves the assembly reliability and sealing performance.

[0081] Of course, a settling groove is provided on the side of the injection hole 111 away from the secondary battery, and the wall of the settling groove is set in a conical shape. The second protective layer 142 in the second sealing structure 140 corresponding to the injection hole 111 is set in a shape adapted to the settling groove to improve sealing performance and assembly reliability.

[0082] like Figure 1 As shown, in actual use, the top cover 110 is also equipped with an explosion-proof valve. When the internal pressure of the battery changes due to temperature variations, the explosion-proof valve can deform accordingly to compensate for the pressure change. For example, when the internal pressure of the battery increases beyond the threshold of the explosion-proof valve, the valve opens and releases pressure, preventing the battery from exploding. Simultaneously, the top cover 110 is also equipped with terminals 150 to ensure current conduction.

[0083] like Figure 1 , Figure 3 and Figure 8 As shown, another embodiment of this application provides a battery, including a battery case, a battery cell and the aforementioned battery top cover 100. The battery case and the battery top cover 100 are encapsulated and fixed together to form an assembly cavity for assembling the battery cell.

[0084] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the patent protection scope of this application should be determined by the appended claims.

Claims

1. A battery top cover characterized by, include: The top cover plate (110) is provided with an injection hole (111) and a replenishment hole (112), wherein the replenishment hole (112) is used for secondary injection after the initial injection; A composite membrane structure (120) is used to seal the liquid replenishment hole (112) and is disposed on the side of the top cover plate (110) facing the secondary battery.

2. The battery header of claim 1, wherein, The composite membrane structure (120) includes at least one adhesive layer (122) and at least one metal layer (121), wherein the adhesive layer (122) and the metal layer (121) are stacked.

3. The battery top cover according to claim 2, characterized in that, The position adjacent to the liquid replenishment hole (112) in the composite membrane structure (120) is set as the metal layer (121) and defined as the first metal layer (1211). The adhesive layer (122) adjacent to the first metal layer (1211) is defined as the first adhesive layer (1221). The projection of the first adhesive layer (1221) along the axial direction (Z) of the fluid replenishment hole is greater than the projection of the first metal layer (1211) along the axial direction (Z) of the fluid replenishment hole.

4. The battery top cover according to claim 3, characterized in that, The projection of the first metal layer (1211) along the axial direction (Z) of the replenishment hole is greater than the projection of the replenishment hole (112) along the axial direction (Z) of the replenishment hole.

5. The battery top cover according to claim 3, characterized in that, The first adhesive layer (1221) has a recess (1220) on the side facing the first metal layer (1211), and the first metal layer (1211) is at least partially accommodated in the recess (1220). The first adhesive layer (1221) is bonded and fixed to the top cover sheet (110) on the periphery of the recess (1220).

6. The battery top cover according to claim 5, characterized in that, The first metal layer (1211) is flush with the side of the top cover plate (110) facing the recess (1220) facing the top cover plate (110).

7. The battery top cover according to claim 3, characterized in that, The liquid replenishment hole (112), the adhesive layer (122), and the metal layer (121) are all circular. The diameter of the liquid replenishment hole (112) is D1, and the diameter of the first adhesive layer (1221) is D3. The metal layer (121) other than the first metal layer (1211) is a stacked metal layer (1212), and the diameter of the stacked metal layer (1212) is D4, then D4 satisfies: D1≤D4≤D3; and / or, the adhesive layer (122) other than the first adhesive layer (1221) is a stacked adhesive layer (1222), and the diameter of the stacked adhesive layer (1222) is D5, then D5 satisfies: D1≤D5≤D3.

8. The battery top cover according to claim 1, characterized in that, The liquid replenishment hole (112) is provided with an assembly step (1121) on the side facing the secondary battery. The assembly step (1121) is recessed from the side of the top cover plate (110) facing the secondary battery to the side of the top cover plate (110) away from the secondary battery. The composite film structure (120) is at least partially accommodated in the assembly step (1121).

9. The battery top cover according to claim 8, characterized in that, The liquid replenishment hole (112) has a conical surface (1123) on the side of the assembly step (1121) away from the secondary battery. The diameter of the conical surface (1123) gradually increases from the inside to the outside of the battery along the axial direction (Z) of the liquid replenishment hole. Along the axial direction (Z) of the replenishment hole, the projection of the composite membrane structure (120) is greater than the projection at the minimum diameter of the conical surface (1123).

10. A battery, characterized in that, The battery includes a battery casing and a battery top cover according to any one of claims 1 to 9, wherein the battery top cover (100) is connected to the battery casing.

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