Secondary battery top cover and secondary battery

Abstract

The application relates to a secondary battery top cover and a secondary battery. The secondary battery top cover comprises a top cover sheet comprising a body, an explosion-proof valve mounting hole and a protection piece, the explosion-proof valve mounting hole is arranged in the body, and the protection piece is integrally formed with the body; and an explosion-proof valve arranged in the explosion-proof valve mounting hole; wherein the protection piece comprises a protection part arranged above or below the explosion-proof valve, the position of the protection part corresponds to the position of the explosion-proof valve in a first direction perpendicular to the body, and the protection part is provided with a first through hole. The secondary battery top cover and the secondary battery can improve the thermal runaway management efficiency of the secondary battery, reduce the risk of thermal runaway, and are low in cost.

Description

Technical Field

[0001] This application relates to the field of energy storage, and more specifically to a secondary battery top cover and a secondary battery including the secondary battery top cover. Background Technology

[0002] Lithium-ion batteries are currently the key electrochemical energy storage batteries used primarily in the energy storage field, possessing outstanding advantages such as high energy density, long cycle life, and low self-discharge. With industry development, the single-cell capacity of electrochemical energy storage lithium-ion batteries has significantly increased, and large-capacity lithium-ion batteries with capacities exceeding 500 Ah have been launched on the market. However, as cell capacity increases, safety issues caused by cell thermal runaway have become increasingly prominent. In recent years, catastrophic accidents caused by thermal runaway during lithium-ion battery applications have been frequently reported, drawing significant attention to battery safety. In energy storage applications, the safety hazard of thermal runaway caused by overcharging is a critical factor affecting the safety of energy storage power stations. Utility Model Content

[0003] This application addresses the technical problem of thermal runaway in battery cells by providing a secondary battery top cover and a secondary battery including the top cover, which can improve the thermal runaway management efficiency of the secondary battery, reduce the risk of thermal runaway, and is low in cost.

[0004] The technical solution adopted in this application to solve the above-mentioned technical problems is a secondary battery top cover, comprising: a top cover sheet, including a body, an explosion-proof valve mounting hole, and a protective component, wherein the explosion-proof valve mounting hole is formed in the body, and the protective component is integrally formed with the body; and an explosion-proof valve, disposed at the explosion-proof valve mounting hole and sealingly engaged with the explosion-proof valve mounting hole; wherein the protective component includes a protective part, which is disposed above or below the explosion-proof valve, and in a first direction perpendicular to the body, the position of the protective part corresponds to the position of the explosion-proof valve, wherein the protective part has a first through hole.

[0005] In one embodiment of this application, the protective member further includes a connecting portion that extends from the body to the protective portion.

[0006] In one embodiment of this application, at least one pole post is further included. The protective part is disposed above the explosion-proof valve. The connecting part has an inner wall surface facing the explosion-proof valve mounting hole and an outer wall surface facing away from the explosion-proof valve mounting hole. The inner wall surface includes at least one first inclined portion. Each first inclined portion corresponds to and is close to one of the pole posts. The first inclined portion is inclined in a direction away from the corresponding pole post.

[0007] In one embodiment of this application, there is a first included angle between the extending direction of the first inclined portion and the extending surface of the body, wherein the first included angle is in the range of [90°, 180°].

[0008] In one embodiment of this application, the range of the first included angle is [115°, 155°].

[0009] In one embodiment of this application, there is a first distance between the upper surface of the protective part and the upper surface of the body, and a second distance between the upper surface of the pole and the upper surface of the body, wherein the first distance is less than or equal to the second distance.

[0010] In one embodiment of this application, the distance between the lower surface of the protective part and the upper surface of the explosion-proof valve is 2.5mm-6mm.

[0011] In one embodiment of this application, the inner wall surface and the wall of the explosion-proof valve mounting hole form a continuous transition.

[0012] In one embodiment of this application, the angle between the extending direction of the hole wall and the extending surface of the body is in the range of [80°, 100°].

[0013] In one embodiment of this application, the angle between the extending direction of the hole wall and the extending surface of the body is equal to 90°.

[0014] In one embodiment of this application, at least one pole post is further included. The protective part is disposed below the explosion-proof valve. The wall of the explosion-proof valve mounting hole includes at least one second inclined part. Each second inclined part corresponds to and is close to one of the pole posts. The second inclined part is inclined in a direction away from the corresponding pole post. The extension direction of the second inclined part has a second included angle with the extension surface of the body. The range of the second included angle is [90°, 180°].

[0015] In one embodiment of this application, the range of the second included angle is [115°, 155°].

[0016] In one embodiment of this application, the protective part is disposed below the explosion-proof valve, and the explosion-proof valve covers the explosion-proof valve mounting hole above the explosion-proof valve mounting hole.

[0017] In one embodiment of this application, an explosion-proof valve mounting groove is provided on the upper surface of the body, and at least a portion of the edge of the explosion-proof valve is fixedly disposed in the explosion-proof valve mounting groove.

[0018] In one embodiment of this application, a plurality of the first through holes are evenly distributed in the protective portion.

[0019] In one embodiment of this application, the thickness of the protective portion along the first direction ranges from 0.15mm to 2mm.

[0020] In one embodiment of this application, the protective part has a first projection on the extension surface of the body, and the explosion-proof valve has a second projection on the extension surface of the body. The first projection is located inside the second projection, and the outline of the first projection does not exceed the outline of the second projection.

[0021] In one embodiment of this application, the total area of ​​the first through hole is greater than or equal to 30% of the explosion-proof valve area and less than or equal to 80% of the explosion-proof valve area.

[0022] In one embodiment of this application, the explosion-proof valve is provided with a groove, and the distance between the junction of the connecting part and the body and the groove in the length direction of the top cover is 1mm-3mm.

[0023] In one embodiment of this application, a lower protective cover is further included, disposed below the explosion-proof valve. The bottom surface of the lower protective cover has a second through hole. The first through hole has a third projection on the extension surface of the main body, and the second through hole has a fourth projection on the extension surface of the main body. The third projection and the fourth projection may overlap or not overlap.

[0024] In one embodiment of this application, the third projection and the fourth projection overlap, and the overlapping area is no greater than 40% of the explosion-proof valve area.

[0025] In one embodiment of this application, the lower protective cover is welded to the lower surface of the body, and a fluid channel is provided between the bottom surface of the lower protective cover and the lower surface of the body, the fluid channel extending along the length direction of the top cover plate.

[0026] In one embodiment of this application, in the first direction, the distance between the bottom surface of the lower protective cover and the protective part is 1.5mm-12mm, wherein, when the protective part is disposed above the explosion-proof valve, the distance is 4mm-12mm, and when the protective part is disposed below the explosion-proof valve, the distance is 1.5mm-7mm.

[0027] To solve the above-mentioned technical problems, this application also proposes a secondary battery, including the secondary battery top cover as described above.

[0028] The secondary battery top cover of this application includes a protective portion disposed above or below an explosion-proof valve, and the protective portion has a first through hole. This protective portion allows heat and pressure to be released through the first through hole when the explosion-proof valve is opened to release pressure; it also prevents or reduces the ejection of flammable materials from the explosion-proof valve mounting hole. The protective component is integrally molded with the main body, giving it sufficient strength to withstand high temperature and pressure, and avoiding the need for additional parts in the secondary battery top cover, thus simplifying its structure and reducing costs. Attached Figure Description

[0029] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings, wherein:

[0030] Figure 1 This is an exploded schematic diagram of the top cover assembly of a lithium-ion battery;

[0031] Figure 2 This is an exploded schematic diagram of the top cover of the secondary battery according to Embodiment 1 of this application;

[0032] Figure 3 This is a top view schematic diagram of the secondary battery top cover of Embodiment 1 of this application;

[0033] Figure 4 This is a front sectional view of the top cover of the secondary battery according to Embodiment 1 of this application;

[0034] Figure 5 yes Figure 4 An enlarged schematic diagram of region A1 in the diagram;

[0035] Figure 6 This is an exploded schematic diagram of the secondary battery top cover according to Embodiment 2 of this application;

[0036] Figure 7 This is a top view schematic diagram of the secondary battery top cover according to Embodiment 2 of this application;

[0037] Figure 8 This is a front sectional view of the top cover of the secondary battery according to Embodiment 2 of this application;

[0038] Figure 9 yes Figure 8 An enlarged schematic diagram of region A2 in the image;

[0039] Figure 10 This is an exploded schematic diagram of the secondary battery top cover according to Embodiment 3 of this application;

[0040] Figure 11 This is a top view schematic diagram of the secondary battery top cover according to Embodiment 3 of this application;

[0041] Figure 12This is a front sectional view of the top cover of the secondary battery according to Embodiment 3 of this application;

[0042] Figure 13 yes Figure 12 An enlarged view of region A3 in the diagram;

[0043] Figure 14 This is a partially enlarged schematic diagram of the protective component on the top cover sheet of the secondary battery in Embodiment 3;

[0044] Figure 15 This is a partial structural schematic diagram of the secondary battery top cover according to another embodiment of this application;

[0045] Figure 16 This is a perspective view of a secondary battery according to an embodiment of this application;

[0046] Figure 17 A perspective view of a secondary battery according to another embodiment of this application. Detailed Implementation

[0047] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0048] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein, and therefore this application is not limited to the specific embodiments disclosed below.

[0049] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0050] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0051] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. In addition, although the terminology used in this application is selected from commonly known and used terms, some terms mentioned in this application's specification may have been chosen by the applicant according to his or her judgment, and their detailed meanings are explained in the relevant sections of this description. Moreover, this application should be understood not only through the actual terms used, but also through the meaning implied by each term.

[0052] The embodiments of this application are described below based on the accompanying drawings. However, the embodiments shown below are examples of a secondary battery top cover and a secondary battery used to embody the technical concept of this application, and the secondary battery top cover and secondary battery of this application are not specifically defined as follows. Furthermore, in order to facilitate understanding of the scope of the claims, the components corresponding to the components shown in the "Claims" and "Utility Model Content" columns are assigned numbers to the components shown in the embodiments. However, the components shown in the claims are not intended to be specific to the components of the embodiments. In particular, the dimensions, materials, shapes, and relative arrangements of the constituent components described in the embodiments are not intended to limit the scope of this application unless specifically stated, but are merely illustrative examples.

[0053] However, the dimensions or positional relationships of the components shown in the accompanying drawings are sometimes exaggerated for clarity. Therefore, in the following description, detailed descriptions of the same names and symbols representing the same or homogeneous components are appropriately omitted. Furthermore, the elements constituting this application may be multiple elements composed of the same components, thus allowing one component to function as multiple elements; conversely, multiple components may share the function of one component. Additionally, the content described in some embodiments and implementations can be applied to other embodiments and implementations. Furthermore, in this specification, "upper" is not limited to the case of being formed in contact with an upper surface, but also includes the case of being formed separately on top, and also includes the meaning of an intermediate layer between layers.

[0054] Figure 1 The image shown is an exploded view of the top cover assembly of a lithium-ion battery. (Reference) Figure 1As shown, the top cover assembly 100 of the lithium-ion battery includes a top cover sheet 110 and a lower plastic sheet 120. The top cover sheet 110 can be a metal sheet, such as a sheet of aluminum or steel. A positive terminal mounting hole 130, a negative terminal mounting hole 140, and an explosion-proof valve mounting hole 150 are formed on the top cover sheet 110. A positive terminal through hole 133 and a negative terminal through hole 143 are formed on the lower plastic sheet 120. The top cover assembly 100 also includes a positive terminal 131, a positive terminal sealing ring 132, and a positive upper plastic sheet 134, as well as a negative terminal 141, a negative terminal sealing ring 142, and a negative upper plastic sheet 144. When the top cover assembly 100 is assembled, the top cover plate 110 and the lower plastic 120 are bonded together. The positive terminal 131 passes through the positive terminal through hole 133, the positive terminal mounting hole 130, and the through hole on the upper plastic 134 in sequence. The negative terminal 141 passes through the negative terminal through hole 143, the negative terminal mounting hole 140, and the through hole on the upper plastic 144 in sequence. The lower plastic 120 is used to isolate the top cover plate 110 from other conductive components inside the battery, preventing direct contact that could lead to a short circuit, and also provides structural support for the top cover plate 110. The upper plastic 134 and the upper plastic 144 are used to isolate the positive terminal 131 and the negative terminal 141 from surrounding potentially conductive components, preventing short circuits, and also serve as structural supports, seals, and corrosion resistant components. The positive terminal 131 and the negative terminal 141 are used to conduct current. In a lithium-ion battery, the positive terminal 131 and the negative terminal 141 can be connected to the cell tabs via adapter plates to ensure the conduction of the cell's charging and discharging current. In a battery module, the positive terminal 131 and the negative terminal 141 are electrically connected to the busbar to form multiple batteries connected in series or in parallel.

[0055] like Figure 1 As shown, the top cover assembly 100 also includes an explosion-proof valve 151, which is disposed in the explosion-proof valve mounting hole 150. An explosion-proof valve film 152 is also disposed on the upper surface of the explosion-proof valve mounting hole 150. When the battery malfunctions, the internal air pressure increases to a certain value, causing the explosion-proof valve 151 to open and release pressure, thereby reducing the risk of battery explosion.

[0056] Lithium-ion batteries typically consist of a casing, a cell, and a top cover assembly. The top cover assembly is positioned above the cell and welded to the casing, thus enclosing the bare cell within the internal space defined by the top cover assembly and the casing. The top cover assembly also serves a sealing function.

[0057] In current applications of high-capacity battery cells, gas flow is only achieved below the explosion-proof valve 151 through the flow-guiding structure 121 on the lower plastic 120. Due to the limited temperature resistance of the lower plastic 120, under high temperature and pressure conditions inside the battery cell, the lower plastic 120 often melts, and may even be ejected in large quantities from the opened explosion-proof valve 151 as a flammable material along with the active materials inside the battery cell, leading to battery cell fire, thermal runaway, and heat propagation.

[0058] This application proposes a secondary battery top cover to solve the aforementioned technical problems. This secondary battery top cover can be applied to various types of secondary batteries, including but not limited to lithium-ion batteries, lead-acid batteries, sodium-ion batteries, and potassium-ion batteries. This application uses a square battery as an example to illustrate the secondary battery top cover and the secondary battery, but it is not intended to limit the shape of the battery to square. Those skilled in the art can apply the secondary battery top cover and secondary battery of this application to cylindrical batteries, blade batteries, etc.

[0059] Figure 2 This is an exploded schematic diagram of the secondary battery top cover of Embodiment 1 of this application. Figure 3 This is a top view schematic diagram of the secondary battery top cover of Embodiment 1 of this application. Figure 4 This is a front sectional view of the top cover of the secondary battery according to Embodiment 1 of this application. Figure 5 yes Figure 4 An enlarged schematic diagram of region A1 in the image. (Combined with...) Figures 2-5 As shown, the secondary battery top cover 200 of Embodiment 1 includes a top cover plate 210 and an explosion-proof valve 220. The top cover plate 210 includes a body 211, an explosion-proof valve mounting hole 212, and a protective member 213. The explosion-proof valve mounting hole 212 is formed in the body 211, and the protective member 213 is integrally formed with the body 211. The explosion-proof valve 220 is disposed at the explosion-proof valve mounting hole 212 and is sealed to it. The protective member 213 includes a protective part 2131, which is disposed above or below the explosion-proof valve 220. In a first direction D1 perpendicular to the body 211, the position of the protective part 2131 corresponds to the position of the explosion-proof valve 220. The protective part 2131 has a first through hole 2132.

[0060] According to Embodiment 1, the secondary battery top cover 200 includes a protective portion 2131 disposed above or below the explosion-proof valve 220, and the protective portion 2131 has a first through hole 2132. This protective portion 2131 allows heat and pressure to be released through the first through hole 2132 when the explosion-proof valve 220 is opened to release pressure; it also prevents or reduces the ejection of flammable materials from the explosion-proof valve mounting hole 212. When the protective portion 2131 is disposed above the explosion-proof valve 220, it can also prevent a ruptured explosion-proof valve 220 from flying out and causing further damage. The protective component 213 is integrally formed with the body 211, giving the protective component 213 a certain strength, preventing damage under high temperature and pressure, and avoiding the addition of extra parts to the secondary battery top cover 200, thus simplifying the structure of the secondary battery top cover 200.

[0061] In some embodiments, the top cover sheet 210 is generally a sheet-like structure. The body 211 refers to the flat plate portion that constitutes the basic structure of the top cover sheet 210. For example... Figure 2As shown, the body 211 has a certain thickness along the first direction D1 and a certain length along the second direction D2, with the first direction D1 perpendicular to the second direction D2. In this application, the first direction D1 is also referred to as the thickness direction of the top cover 210 or the body 211, and the second direction D2 is referred to as the length direction of the top cover 210 or the body 211.

[0062] In some embodiments, the body 211 is made of metal and has a certain strength or hardness. In some embodiments, the body 211 is a sheet of aluminum, and the protective member 213 is integrally formed from the sheet of aluminum. In other embodiments, the body 211 is a sheet of steel, and the protective member 213 is integrally formed from the sheet of steel.

[0063] In some embodiments, integral molding is achieved through a stamping process.

[0064] exist Figures 2-5 In the secondary battery top cover 200 shown, the protective part 2131 is disposed above the explosion-proof valve 220. In this first embodiment, the protective member 213 is formed by upward stamping of the body 211. After forming, a plurality of first through holes 2132 are opened on the protective part 2131 to form the protective member 213.

[0065] like Figure 3 As shown, in some embodiments, the first through holes 2132 are evenly distributed on the protective portion 2131. When a battery experiences thermal runaway, since the location of the runaway trigger point inside the cell is unknown, the even distribution of the first through holes 2132 is suitable for runaway trigger points at various locations.

[0066] In some embodiments, the size of the first through hole 2132 located in the middle of the protective part 2131 is larger, and the size of the first through hole 2132 located at the edge of the protective part 2131 is smaller, thereby achieving a better instantaneous pressure relief effect.

[0067] like Figure 3 As shown, the first through hole 2132 can be a circular hole. In other embodiments, the first through hole 2132 can be of any shape.

[0068] In some embodiments, the thickness of the protective portion 2131 along the first direction D1 ranges from 0.15mm to 2mm. For example, the thickness is 0.15mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, or 2mm.

[0069] In some embodiments, the thickness of the protective portion 2131 along the first direction D1 is less than the thickness of the body 211 along the first direction D1. When the body 211 is a smooth aluminum sheet, the thickness of the body 211 is approximately 2.5 mm. Setting the thickness of the protective portion 2131 to between 0.15 mm and 2 mm can reduce the weight of the top cover while ensuring mechanical strength.

[0070] Combination Figure 2 and Figure 3 As shown, the explosion-proof valve mounting hole 212 is formed on the body 211, for example, it can be formed at the center of the body 211. Figure 2 As shown, the explosion-proof valve 220 typically has a racetrack-shaped profile, and correspondingly, the explosion-proof valve mounting hole 212 also has a racetrack-shaped profile. Correspondingly, the protective portion 2131 also has a racetrack-shaped profile. In other embodiments, the explosion-proof valve 220 can have other shapes, with the shape of the explosion-proof valve mounting hole 212 adapted to the explosion-proof valve 220, and the shape of the protective portion 2131 adapted to the explosion-proof valve 220. By adapting the shape of the protective portion 2131 to the explosion-proof valve 220, the protective portion 2131 can better cooperate with the explosion-proof valve 220, achieving better flow guidance, which is beneficial for the release of gas and heat inside the battery cell, and for preventing the ejection of flammable materials.

[0071] In some embodiments, the total area of ​​the first through holes 2132 is greater than or equal to 30% and less than or equal to 80% of the explosion-proof valve area of ​​the explosion-proof valve 220. For example, the total area of ​​the first through holes 2132 is 30%, 40%, 50%, 60%, 70%, or 80% of the explosion-proof valve area. The total area of ​​the first through holes 2132 is the sum of the areas of all the first through holes 2132 on the protective part 2131. If the total area of ​​the first through holes 2132 is too small, it will hinder airflow and heat dissipation after the explosion-proof valve 220 is opened. If the total area of ​​the first through holes 2132 is too large, it will hinder the blocking of solid combustibles from being ejected from the battery cell. Therefore, by setting the range of the total area of ​​the first through holes 2132, the protective part 2131 can ensure airflow without hindering the battery's heat dissipation and also block the ejection of solid combustibles.

[0072] like Figure 3 and Figure 5As shown, in some embodiments, the protective member 213 further includes a connecting portion 2133, which extends from the body 211 to the protective portion 2131. In some embodiments, a countersunk hole can be first formed on the lower surface of the body 111 to create an explosion-proof valve mounting hole 212, and then the protective portion 2131 and the connecting portion 2133 can be formed by punching upwards at the countersunk hole and using a suitable mold. Afterwards, a first through hole 2132 is formed on the protective portion 2131. According to the above-described method of forming the connecting portion 2133, the inner wall surface 2133b of the connecting portion 2133 facing the explosion-proof valve mounting hole 212 forms a continuous transition with the hole wall 2121 of the explosion-proof valve mounting hole 212, such as... Figure 5 As shown. It should be noted that in... Figure 5 In the illustrated embodiment, the hole wall 2121 extends along the first direction D1. In other embodiments, the hole wall 2121 may extend along other directions.

[0073] In some embodiments, the secondary battery top cover further includes at least one terminal post. For example... Figure 2 and Figure 3 As shown, this embodiment includes two terminals, namely a positive terminal 231 and a negative terminal 241. In these embodiments, the protective part 2131 is disposed above the explosion-proof valve 220, as shown in the reference. Figure 5 As shown, the connecting portion 2133 has an inner wall surface 2133b facing the explosion-proof valve mounting hole 212 and an outer wall surface 2133a facing away from the explosion-proof valve mounting hole 212. The inner wall surface 2133b includes at least one first inclined portion, each first inclined portion corresponding to and close to a pole post, the first inclined portion being inclined in a direction away from the corresponding pole post. Figure 3 and Figure 4 As shown, the connecting portion 2133 surrounds the outer ring of the protective portion 2131. Taking a racetrack-shaped profile as an example, the curves at both ends are close to the positive terminal 231 and the negative terminal 241, respectively. One first inclined portion is located at curve 21341, corresponding to and close to the positive terminal 231, and inclined away from the positive terminal 231. Another first inclined portion is located at curve 21342, corresponding to and close to the negative terminal 241, and inclined away from the negative terminal 241.

[0074] According to these embodiments, when combustible material is ejected, the two first inclined portions of the inner wall surface 2133b of the connecting portion 2133 can respectively guide the combustible material to be ejected in a direction away from their respective corresponding poles, so as to avoid the combustible material from contacting the poles and causing greater harm.

[0075] In some embodiments, the connecting portion 2133 with a racetrack-shaped profile may also be inclined inward toward the protective portion 2131 at the straight sections on both sides, thereby making the protective member 213 as a whole have an upward and inward tapering structure, further defining and guiding the combustible material and its ejection direction. The connecting portion 2133 is equivalent to forming a protective wall above the explosion-proof valve 220, and together with the protective portion 2131, it is used to guide the ejection direction of the combustible material, especially to make the combustible material eject away from the pole, confining the combustible material within a certain space, preventing the combustible material from contacting the pole, thereby preventing the pole from melting and reducing the risk of thermal runaway.

[0076] It should be noted that, for embodiments that include only one pole post, the inner wall surface 2133b of the connecting part 2133 may be set to be inclined in the direction away from the pole post only at one end or part of the end near the pole post.

[0077] It should be noted that, for example Figure 5 As shown, in some embodiments, the outer wall surface 2133a of the connecting portion 2133 is parallel to the inner wall surface 2133b; therefore, the outer wall surface 2133a is also inclined away from the corresponding pole post. In other embodiments, the outer wall surface 2133a may not be parallel to the inner wall surface 2133b. For example, the outer wall surface 2133a may extend along the first direction D1, i.e., perpendicular to the body 211.

[0078] In some embodiments, there is a first included angle α between the extending direction of the first inclined portion and the extending surface of the body 211, and the range of the first included angle α is [90°, 180°]. For example, the first included angle α is 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, 170°, or 179°. It should be noted that... Figure 5 The upper surface 2111 of the body 211 was selected. The body 211 itself is a plate-like structure, and the extension surface of the body 211 is parallel to the upper surface 2111.

[0079] Preferably, in one embodiment, the range of the first included angle α is [115°, 155°]. For example, the first included angle α is 115°, 120°, 125°, 130°, 135°, 140°, 145°, 150°, or 155°.

[0080] like Figure 3As shown, when combustible material is ejected from the explosion-proof valve mounting hole 212, the connecting part 2133 acts as a guide and shield, allowing the combustible material to be ejected along the extension direction of the inner wall surface 2133b of the connecting part 2133. When the first included angle α equals 90°, it is equivalent to the inner wall surface 2133b of the connecting part 2133 extending along the first direction D1. At this time, if combustible material is ejected, the connecting part 2133 guides the combustible material to be ejected upward along the first direction D1. A small amount of combustible material may be ejected through the first through hole 2132, while the remaining combustible material will be shielded by the protective part 2131.

[0081] like Figure 2 and Figure 3 As shown, in some embodiments, the secondary battery top cover 200 further includes a positive terminal post 231, a negative terminal post 241, and a lower plastic 250. Correspondingly, the top cover sheet 210 also includes a positive terminal post hole 230 and a negative terminal post hole 240. The secondary battery top cover 200 also includes an upper positive terminal plastic 234 and an upper negative terminal plastic 244. The lower plastic 250 also includes a positive terminal post through hole 233 and a negative terminal post through hole 243. After assembly, the positive terminal post 231 is sequentially inserted into the positive terminal post through hole 233, the positive terminal post hole 230, and the through hole on the upper positive terminal plastic 234, and the negative terminal post 241 is sequentially inserted into the negative terminal post through hole 243, the negative terminal post hole 240, and the through hole on the upper negative terminal plastic 244.

[0082] refer to Figure 4 and Figure 5 As shown, taking the positive terminal post 231 as an example, there is a first distance H1 between the upper surface 21311 of the protective part 2131 and the upper surface 2111 of the body 211, and a second distance H2 between the upper surface 2311 of the terminal post 231 and the upper surface 2111 of the body 211. The first distance H1 is less than or equal to the second distance H2. By setting H1 to be less than or equal to H2, the height H1 of the protective member 213 protruding from the upper surface 2111 is not higher than the height H2 of the terminal post protruding from the upper surface 2111. Thus, in the battery module, the terminals of multiple batteries are connected by a busbar, and the setting of the protective member 213 will not hinder the setting of the busbar, nor will it interfere with the busbar or other parts in the battery module. At the same time, the secondary battery top cover 200 of this embodiment will not increase the height of the battery module in the height direction and will not affect the setting of the battery pack.

[0083] It should be noted that in the above embodiments, the upper surface 21311 of the protective part 2131 and the upper surface 2111 of the body 211 are both planes, and their extending directions are parallel. Therefore, the first distance H1 can be the distance between the two planes. In other embodiments, there may be cases where the upper surface 21311 of the protective part 2131 and / or the upper surface 2111 of the body 211 are not planes, but may be non-planar. In this case, the first distance H1 can be the maximum distance between them in the first direction D1. Similarly, for the second distance H2, when the upper surface 2311 of the pole post 231 and the upper surface 2111 of the body 211 are mutually parallel planes, the second distance H2 can be the distance between the two planes; when the upper surface 2311 of the pole post 231 and / or the upper surface 2111 of the body 211 are not planes, the second distance H2 can be the maximum distance between them in the first direction D1.

[0084] In one embodiment, H1=H2. According to this embodiment, on the one hand, the protective component 213 will not interfere with the components of the battery module, and on the other hand, the height of the protective component 213 is high enough to provide a large opening space for the explosion-proof valve 220, which is beneficial to the normal operation of the explosion-proof valve 220.

[0085] In some embodiments, in the first direction D1, the position of the protective part 2131 corresponds to the position of the explosion-proof valve 220, indicating that the position of the protective part 2131 is close to the position of the explosion-proof valve 220, such that the protective part 2131 is at least partially located above the explosion-proof valve 220, and the projection of the protective part 2131 along the first direction D1 overlaps with the projection of the explosion-proof valve 220 along the first direction D1.

[0086] In some embodiments, the protective part 2131 is located directly above the explosion-proof valve 220, that is, the geometric centers of the protective part 2131 and the explosion-proof valve 220 coincide on the same plane.

[0087] In some embodiments, the protective part 2131 has a first length L1 in the second direction D2, and the explosion-proof valve 220 has a second length L2 in the second direction D2, wherein the first length L1 is smaller than the second length L2. Figure 5 As shown, an explosion-proof valve mounting groove 221 can be formed on the lower surface 2112 of the body 211 of the top cover plate 210, through which the explosion-proof valve 220 can be welded to the lower surface 2112. In some embodiments, the explosion-proof valve mounting groove 221 is a countersunk hole. These embodiments demonstrate the guiding function of the protective part 2131 in terms of length by making L1 smaller than L2. It should be noted that... Figure 5 The following is along Figure 3The cross-sectional view obtained by cutting along cutting line C1. For the runway-shaped explosion-proof valve 220, L2 is the length of the cross-section obtained by cutting along cutting line C1. When cutting line C1 is parallel to the long side of the explosion-proof valve 220 and passes through the geometric center of the explosion-proof valve 220, L2 is the longest straight length of the explosion-proof valve 220. Similarly, L1 is also the longest straight length of the protective part 2131 with the runway-shaped profile.

[0088] In some embodiments, the protective portion 2131 has a first projection on the extended surface of the body 211, and the explosion-proof valve 220 has a second projection on the extended surface of the body 211. The first projection is located inside the second projection, and the outline of the first projection does not exceed the outline of the second projection. According to these embodiments, the size relationship and relative position of the protective portion 2131 and the explosion-proof valve 220 are more specifically defined. The overall area of ​​the protective portion 2131 is smaller than the overall area of ​​the explosion-proof valve 220. According to these embodiments, for the top cover 210, the position of the protective portion 2131 corresponds to the explosion-proof valve mounting hole 212. Therefore, the explosion-proof valve mounting hole 212 and the protective portion 213 can be formed simultaneously or sequentially by integrally stamping the body 211, simplifying the manufacturing process.

[0089] refer to Figure 5 In some embodiments, the distance H0 between the lower surface of the protective part 2131 and the upper surface of the explosion-proof valve 220 is 2.5mm-6mm. By setting the distance H0, sufficient space is provided between the protective part 2131 and the explosion-proof valve 220, allowing airflow to pass smoothly. At the same time, when the explosion-proof valve 220 breaks due to impact, space is provided to allow the explosion-proof valve 220 to flip upward, which is beneficial for airflow to be ejected from the battery to relieve pressure.

[0090] refer to Figure 5 In some embodiments, the explosion-proof valve 220 is provided with a notch 222, and the distance between the junction 2113 of the connecting part 2133 and the body 211 and the notch 222 in the length direction of the top cover plate 110 is 1mm-3mm. It should be noted that the junction 2113 here can also specifically be the junction of the inner wall surface 2133b of the connecting part 2133 and the hole wall 2121. For example, this distance is 1mm, 2mm, or 3mm. According to... Figure 5 As shown, the junction 2113 is located on the outer ring of the notch 222. On the one hand, this arrangement is conducive to the welding of the explosion-proof valve 220 at the explosion-proof valve mounting groove 221, so that the body 211 provides support for the explosion-proof valve 220. On the other hand, it can ensure that when the internal gas pressure of the battery is high and impacts the explosion-proof valve 220, the explosion-proof valve 220 will disconnect from the notch 222, thereby opening the explosion-proof valve 220 to release pressure.

[0091] Furthermore, as previously described, the inner wall surface 2133b and the hole wall 2121 form a continuous transition. In some embodiments, the angle between the extending direction of the hole wall 2121 and the extending surface of the body 211 ranges from [80°, 100°]. Preferably, this angle is equal to 90°, such as... Figure 5 As shown. That is, the hole wall 2121 extends along the first direction D1, perpendicular to the extension surface of the body 211. When the included angle is too small, for example less than 80°, it may hinder the explosion-proof valve 220 from flipping upward when it breaks off from the notch 222; if the included angle is too large, for example greater than 100°, it is not conducive to the body 211 providing support for the explosion-proof valve 220, nor is it conducive to demolding after the opening is formed. Therefore, by setting the included angle between the extension direction of the hole wall 2121 and the extension surface of the body 211 to a range of [80°, 100°], sufficient space can be provided for the explosion-proof valve 220 to flip upward, while also facilitating the body 211 to provide support for the explosion-proof valve 220.

[0092] Figure 6 This is an exploded schematic diagram of the secondary battery top cover of Embodiment 2 of this application. Figure 7 This is a top view schematic diagram of the secondary battery top cover of Embodiment 2 of this application. Figure 8 This is a front sectional view of the top cover of the secondary battery according to Embodiment 2 of this application. Figure 9 yes Figure 8 An enlarged schematic diagram of region A2 is shown. It should be noted that the secondary battery top cover 600 of Embodiment 2 is largely similar in structure to the secondary battery top cover 200 of Embodiment 1; identical structures are represented by the same reference numerals. The difference between Embodiment 2 and Embodiment 1 includes that in Embodiment 2, the secondary battery top cover 600 further includes a lower protective cover 610. (Combined with...) Figures 6-9 As shown, the secondary battery top cover 600 includes a top cover plate 210 and an explosion-proof valve 220. The top cover plate 210 includes a body 211, an explosion-proof valve mounting hole 212, and a protective member 213. The explosion-proof valve mounting hole 212 is formed in the body 211, and the protective member 213 is integrally formed with the body 211. The explosion-proof valve 220 is disposed within the explosion-proof valve mounting hole 212. The protective member 213 includes a protective part 2131, which is disposed above or below the explosion-proof valve 220. In a first direction D1 perpendicular to the body 211, the position of the protective part 2131 corresponds to the position of the explosion-proof valve 220. The protective part 2131 has a first through hole 2132.

[0093] In Embodiment 2, for components with the same reference numerals as in Embodiment 1, the descriptions can refer to the descriptions in Embodiment 1 above, and will not be elaborated further.

[0094] In Embodiment 2, the lower protective cover 610 is positioned below the explosion-proof valve 220. The bottom surface 611 of the lower protective cover 610 has a second through hole 612. The first through hole 2132 has a third projection on the extended surface of the body 211, and the second through hole 612 has a fourth projection on the extended surface of the body 211. The third and fourth projections may overlap or not overlap. When the third and fourth projections do not overlap, it indicates that the first through hole 2132 and the second through hole 612 are completely offset. According to this embodiment, solid combustibles can be prevented from being ejected from the battery cell to the greatest extent possible.

[0095] When the third and fourth projections overlap, the overlapping area of ​​the third and fourth projections is no more than 40% of the explosion-proof valve area of ​​the explosion-proof valve 220. For example, the overlapping area of ​​the third and fourth projections is 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40% of the explosion-proof valve area of ​​the explosion-proof valve 220. Preferably, the overlapping area of ​​the third and fourth projections is 20-40% of the explosion-proof valve area of ​​the explosion-proof valve 220.

[0096] In one embodiment, the overlapping area of ​​the third and fourth projections is 30% of the explosion-proof valve area of ​​the explosion-proof valve 220. According to this embodiment, the protective component 213 can both ensure the flow of gas and prevent solid combustibles from being ejected from the battery cell as much as possible, achieving an optimal balance between the two effects.

[0097] like Figure 6 and Figure 9 As shown, in some embodiments, the lower protective cover 610 is welded to the lower surface 2112 of the body 211. A fluid channel 613 is provided between the bottom surface 611 and the lower surface 2112 of the lower protective cover 610. The fluid channel 613 extends along the length direction of the top cover 210, i.e., the second direction D2. In some embodiments, the lower protective cover 610 includes a bottom surface 611 and a welding portion 614. In this second embodiment, the bottom surface 611 is rectangular, and a welding portion 614 is provided on each of its two corresponding long sides. The welding portion 614 may be perpendicular to the bottom surface 611, and the top end of the welding portion 614 is welded to the lower surface 2112 of the body 211, thereby fixing the lower protective cover 610 below the body 211. The two corresponding short sides of the bottom surface 611 do not have welding portions 614, forming open sections. This allows airflow to enter the upper part of the bottom surface 611 through these two open sections, thus forming a fluid channel 613 between the bottom surface 611 and the lower surface 2112. The illustration is only an example; in other embodiments, the welding portions 614 may only be provided on the two short sides of the bottom surface 611, and the bottom surface 611 may have other shapes. By designing the lower protective cover 610 to have a fluid channel 613, it is beneficial for gas circulation and heat dissipation from the battery cell.

[0098] In some embodiments, the distance between the lower protective cover 610 and the protective part 213 in the first direction D1 is 1.5mm-12mm. For example, this distance is: 1.5mm, 3mm, 4.5mm, 6mm, 7.5mm, 9mm, 10.5mm, 12mm. Specifically, for embodiments where the protective part 213 is located above the explosion-proof valve 220, this distance is 4mm-12mm; for embodiments where the protective part 213 is located below the explosion-proof valve 220, this distance is 1.5mm-7mm. Figure 9 As shown, the distance between the lower protective cover 610 and the protective part 2131 can be specifically defined as the distance H3 between the lower surface of the bottom surface 611 of the lower protective cover 610 and the upper surface 21311 of the protective part 2131. This distance setting allows the secondary battery top cover 600 to cover all currently available battery cell models. For example, for larger battery cells, this distance H3 can be larger, and for smaller battery cells, this distance H3 can be smaller.

[0099] The minimum value of H3 can be equal to the sum of the thickness of the body 211 and the height of the lower protective cover 610 in the first direction D1. In this embodiment, the protective portion 2131 and the connecting portion 2133 in the protective member 213 both extend along the second direction D2 and are flush with the upper surface 2111 of the body 211.

[0100] It should be noted that in both Embodiment 1 and Embodiment 2, the protective part 2131 is located above the explosion-proof valve 220; therefore, it is not necessary to add any additional protective parts. Figure 1 The explosion-proof valve liner 152 shown reduces the number of parts and cost.

[0101] Figure 10 This is an exploded schematic diagram of the secondary battery top cover of Embodiment 3 of this application. Figure 11 This is a top view schematic diagram of the secondary battery top cover of Embodiment 3 of this application. Figure 12 This is a front sectional view of the top cover of the secondary battery according to Embodiment 3 of this application. Figure 13 yes Figure 12 An enlarged schematic diagram of area A3 is shown. It should be noted that the secondary battery top cover 1000 of Embodiment 3 is largely similar in structure to the secondary battery top cover 200 of Embodiment 1, and the same structures are represented by the same reference numerals. The differences between Embodiment 3 and Embodiment 1 include: In Embodiment 3, the protective component 1010 of the secondary battery top cover 1000 includes a protective part 1011, which is located below the explosion-proof valve 220. In the first direction D1 perpendicular to the body 211, the position of the protective part 1011 corresponds to the position of the explosion-proof valve 220, wherein the protective part 1011 has a first through hole 1012.

[0102] In this third embodiment, the protective component 1011 is formed by downward stamping from the body 211. The protective component 1011 may be in the form of a thin sheet.

[0103] In some embodiments, the first through holes 1012 are evenly distributed on the protective portion 1011.

[0104] In some embodiments, the protective part 1011 is disposed below the explosion-proof valve 220, and the explosion-proof valve 220 covers the explosion-proof valve mounting hole 212 above the explosion-proof valve mounting hole 212.

[0105] like Figure 13 As shown, in some embodiments, an explosion-proof valve mounting groove 1020 is formed on the upper surface 2111 of the body 211 near the wall of the explosion-proof valve mounting hole 212. At least a portion of the edge of the explosion-proof valve 220 can be welded to the body 211 through the explosion-proof valve mounting groove 1020. In this way, the explosion-proof valve 220 can seal the explosion-proof valve mounting hole 212. In other embodiments, the explosion-proof valve 220 can also be directly welded to the upper surface 2111 of the body 211, without the need to provide an explosion-proof valve mounting groove 1020 on the upper surface 2111 of the body 211. In this case, the upper surface of the explosion-proof valve 220 is higher than the upper surface 2111 of the body 211.

[0106] Compared to the upward-stamped protective component 213 in Embodiment 1, the downward-stamped protective component 1011 in Embodiment 3 has a relatively simpler process. Furthermore, since the explosion-proof valve 220 is located on the upper surface 2111 of the body 211, welding of the explosion-proof valve 220 can be performed above the top cover, i.e., outside the battery cell. This avoids welding slag falling into the battery cell and thus preventing the risk of a short circuit, thereby improving the safety and reliability of the battery cell.

[0107] In some embodiments, the protective part 1011 is disposed below the explosion-proof valve 220. For example... Figure 13 As shown, the protective part 1011 can be formed by downward stamping. Figure 14 This is a partially enlarged schematic diagram of the protective component on the top cover sheet of the secondary battery in Embodiment 3. Figure 14 The diagram shows the main body 211 of the top cover 210 and the protective part 1011 integrally formed with the main body 211.

[0108] In some embodiments, the secondary battery top cover further includes at least one terminal post. For example... Figure 11 As shown, similar to Embodiment 1, the top cover 210 includes a positive terminal 231 and a negative terminal 241. (Reference) Figure 15 As shown, the wall 2121 of the explosion-proof valve mounting hole 212 includes at least one second inclined portion, each second inclined portion corresponding to and close to a pole post, and the second inclined portion is inclined in a direction away from the corresponding pole post. Similar to Embodiment 1, refer to... Figure 11As shown, a second inclined section is located at bend 21341, corresponding to and close to the positive terminal 231, and inclined in a direction away from the positive terminal 231. Another second inclined section is located at bend 21342, corresponding to and close to the negative terminal 241, and inclined in a direction away from the negative terminal 241. The extension direction of the second inclined section (e.g.) Figure 15 The extended dashed line (as shown in the image) forms a second included angle β with the extended surface of the body 211 (parallel to the upper surface of the body 211), the second included angle β being in the range of [90°, 180°]. Figure 15 As shown.

[0109] exist Figure 13 and Figure 14 In the embodiment shown, the second included angle β is equal to 90°. Figure 15 Is Figure 13 The design was modified based on the previous one, with the only difference being that the second included angle between the hole wall 2121 and the protective part 1011 is an obtuse angle. Preferably, in some embodiments, the range of the second included angle β is [115°, 155°].

[0110] This second included angle β design also helps guide the direction of the combustible material ejection, directing it away from the pole.

[0111] like Figure 13 As shown, the explosion-proof valve 220 has a notch 1030. The junction of the hole wall 2121 and the body, i.e., the top of the hole wall 2121, has a notch 1030. The distance between the notch 1030 and the top of the hole wall 2121 along the length of the top cover plate 210 is 1mm-3mm. This design allows the body 211 to effectively support the explosion-proof valve 220 without preventing the explosion-proof valve 220 from breaking at the notch 1030 when subjected to impact.

[0112] In Embodiment 3, the configuration of the first through hole 1012, its total area, and the thickness of the protective part 1011 are the same as those of the first through hole 2132 and the protective part 2131 in Embodiment 1, and will not be elaborated further.

[0113] like Figure 10 and Figure 13 As shown, in Embodiment 3, the secondary battery top cover 1000 also includes an explosion-proof valve film 1040, which is attached above the explosion-proof valve 220.

[0114] In other embodiments, based on Embodiment 3, a lower protective cover (not shown) as in Embodiment 2 can be added below the protective part 1011. The overlapping area of ​​the projections of the second through hole on the lower protective cover and the first through hole 1012 on the protective part 1011 is 0-40% of the explosion-proof valve area of ​​the explosion-proof valve 220. When the overlapping area is 0, it indicates that the second through hole and the first through hole 1012 are completely offset.

[0115] This application also proposes a secondary battery, including a secondary battery top cover as described in any of the preceding embodiments. Figure 16 This is a perspective view of a secondary battery according to an embodiment of this application. The secondary battery 1600 includes a housing 1610 and a secondary battery top cover 1620. The secondary battery top cover 1620 may be the secondary battery top cover 200 in Embodiment 1 or the secondary battery top cover 600 in Embodiment 2. Figure 17 A perspective view of a secondary battery according to another embodiment of this application. The secondary battery 1700 includes a housing 1710 and a secondary battery top cover 1720. The secondary battery top cover 1720 may be the secondary battery top cover 1000 described in Embodiment 3 above.

[0116] The secondary battery of this application, by including the secondary battery top cover of this application, can improve the thermal runaway management efficiency of the secondary battery, reduce the risk of thermal runaway, and has low cost.

[0117] While the foregoing disclosure has discussed various embodiments that are currently considered useful, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. Rather, the claims are intended to cover all modifications and equivalent combinations that conform to the spirit and scope of the embodiments of this application. For example, although the system components described above can be implemented by hardware devices, they can also be implemented solely by software solutions, such as installing the described system on existing servers or mobile devices.

[0118] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the present application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0119] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of scope in some embodiments of this application are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

Claims

1. A top cover for a secondary battery, characterized in that, include: The top cover includes a body, an explosion-proof valve mounting hole, and a protective component. The explosion-proof valve mounting hole is formed in the body, and the protective component is integrally formed with the body. An explosion-proof valve is disposed at the explosion-proof valve mounting hole and is sealed to the explosion-proof valve mounting hole; The protective component includes a protective part, which is disposed above or below the explosion-proof valve. In a first direction perpendicular to the body, the position of the protective part corresponds to the position of the explosion-proof valve. The protective part has a first through hole.

2. The secondary battery top cover as described in claim 1, characterized in that, The protective component also includes a connecting portion that extends from the body to the protective portion.

3. The secondary battery top cover as described in claim 2, characterized in that, It also includes at least one pole post, the protective part is disposed above the explosion-proof valve, the connecting part has an inner wall surface facing the explosion-proof valve mounting hole and an outer wall surface facing away from the explosion-proof valve mounting hole, the inner wall surface includes at least one first inclined part, each first inclined part corresponds to and is close to one of the pole posts, and the first inclined part is inclined in a direction away from the corresponding pole post.

4. The secondary battery top cover as described in claim 3, characterized in that, The first inclined portion has a first included angle between its extending direction and the extending surface of the body, and the first included angle is in the range of [90°, 180°].

5. The secondary battery top cover as described in claim 4, characterized in that, The range of the first included angle is [115°, 155°].

6. The secondary battery top cover as described in claim 3, characterized in that, There is a first distance between the upper surface of the protective part and the upper surface of the body, and there is a second distance between the upper surface of the pole and the upper surface of the body, wherein the first distance is less than or equal to the second distance.

7. The secondary battery top cover as described in claim 3, characterized in that, The distance between the lower surface of the protective part and the upper surface of the explosion-proof valve is 2.5mm-6mm.

8. The secondary battery top cover as described in claim 3, characterized in that, The inner wall surface and the hole wall of the explosion-proof valve mounting hole form a continuous transition.

9. The secondary battery top cover as described in claim 8, characterized in that, The angle between the extending direction of the hole wall and the extending surface of the body is in the range of [80°, 100°].

10. The secondary battery top cover as described in claim 9, characterized in that, The angle between the extending direction of the hole wall and the extending surface of the body is 90°.

11. The secondary battery top cover as described in claim 1, characterized in that, It also includes at least one pole post, the protective part is disposed below the explosion-proof valve, the wall of the explosion-proof valve mounting hole includes at least one second inclined part, each second inclined part corresponds to and is close to one of the pole posts, the second inclined part is inclined in a direction away from the corresponding pole post, wherein the extension direction of the second inclined part has a second included angle with the extension surface of the body, the second included angle being in the range of [90°, 180°).

12. The secondary battery top cover as described in claim 11, characterized in that, The range of the second included angle is [115°, 155°].

13. The secondary battery top cover as described in claim 1, characterized in that, The protective part is located below the explosion-proof valve, and the explosion-proof valve covers the explosion-proof valve mounting hole above it.

14. The secondary battery top cover as described in claim 13, characterized in that, The upper surface of the body is provided with an explosion-proof valve mounting groove, and at least a portion of the edge of the explosion-proof valve is fixedly disposed in the explosion-proof valve mounting groove.

15. The secondary battery top cover as described in any one of claims 1-14, characterized in that, The plurality of first through holes are evenly distributed in the protective part.

16. The secondary battery top cover as described in any one of claims 1-14, characterized in that, The thickness of the protective part along the first direction ranges from 0.15mm to 2mm.

17. The secondary battery top cover as described in any one of claims 1-14, characterized in that, The protective part has a first projection on the extension surface of the body, and the explosion-proof valve has a second projection on the extension surface of the body. The first projection is located inside the second projection, and the outline of the first projection does not exceed the outline of the second projection.

18. The secondary battery top cover as described in any one of claims 1-14, characterized in that, The total area of ​​the first through hole is greater than or equal to 30% of the explosion-proof valve area and less than or equal to 80% of the explosion-proof valve area.

19. The secondary battery top cover as described in any one of claims 2-10, characterized in that, The explosion-proof valve is provided with grooves, and the distance between the junction of the connecting part and the body and the grooves in the length direction of the top cover is 1mm-3mm.

20. The secondary battery top cover as described in any one of claims 1-14, characterized in that, It also includes a lower protective cover, which is disposed below the explosion-proof valve. The bottom surface of the lower protective cover has a second through hole. The first through hole has a third projection on the extension surface of the main body, and the second through hole has a fourth projection on the extension surface of the main body. The third projection and the fourth projection may overlap or not overlap.

21. The secondary battery top cover as described in claim 20, characterized in that, The third projection and the fourth projection overlap, and the overlapping area is no more than 40% of the explosion-proof valve area.

22. The secondary battery top cover as described in claim 20, characterized in that, The lower protective cover is welded to the lower surface of the main body, and a fluid channel is provided between the bottom surface of the lower protective cover and the lower surface of the main body, the fluid channel extending along the length direction of the top cover plate.

23. The secondary battery top cover as described in claim 20, characterized in that, In the first direction, the distance between the bottom surface of the lower protective cover and the protective part is 1.5mm-12mm. Wherein, if the protective part is located above the explosion-proof valve, the distance is 4mm-12mm, and if the protective part is located below the explosion-proof valve, the distance is 1.5mm-7mm.

24. A secondary battery, characterized in that, Includes the secondary battery top cover as described in any one of claims 1-23.

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