Secondary battery, battery pack, and electric device

Abstract

The invention discloses a secondary battery, a battery pack and a power utilization device, the secondary battery comprises a shell, an electrode assembly and a top cover assembly, and the shell is provided with an accommodating cavity for accommodating the electrode assembly; the top cover assembly comprises a top cover sheet and a lower insulating part; the top cover sheet is connected with the shell and covers the accommodating cavity; the lower insulating part is connected between the top cover plate and the electrode assembly; a pressure relief piece is arranged on the top cover piece, the lower insulating piece is provided with a second groove, the second groove is formed in the side, facing the electrode assembly, of the lower insulating piece, and the second groove is communicated with the containing cavity; the second groove is provided with a second bottom wall, the second bottom wall and the pressure relief piece are arranged at an interval, and the second bottom wall is configured to be exploded when the internal pressure of the secondary battery reaches a threshold value, so that the internal pressure of the secondary battery directly acts on the pressure relief piece. The second groove is formed in the lower insulating part, the second bottom wall is used for shielding the top cover piece so as to reduce the area, exposed out of metal, of the top cover piece, normal pressure relief of the battery is achieved through explosion of the second bottom wall, and the safety of the secondary battery is improved.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and specifically relates to a secondary battery, a battery pack and an electrical device. Background Art

[0002] The top cover assembly of a secondary battery usually includes a lower insulating member of the top cover sheet, an explosion-proof valve is arranged on the top cover sheet, and the lower insulating member is spaced between the top cover sheet and the electrode assembly and an exhaust hole is arranged at a position opposite to the explosion-proof valve, so that when the battery produces gas abnormally, the gas is transmitted to the explosion-proof valve so that the explosion-proof valve opens to release the internal pressure and prevent the battery from exploding. However, the pole ear or other metal foreign matter of the electrode assembly may also overlap with the explosion-proof valve through the exhaust hole, resulting in the problem of internal short circuit of the battery, and then there is a risk of corrosion and cracking of the explosion-proof valve. Summary of the invention

[0003] Purpose of the invention: An embodiment of the present application provides a secondary battery, aiming to solve the problem of short circuit caused by the tabs or other metal foreign matter in the existing battery through the exhaust holes of the lower insulating part and the explosion-proof valve; another purpose of the embodiment of the present application is to provide a battery pack, and another purpose of the embodiment of the present application is to provide an electrical device.

[0004] Technical solution: A secondary battery described in an embodiment of the present application includes:

[0005] A housing having a receiving cavity;

[0006] An electrode assembly, disposed in the accommodating cavity;

[0007] A top cover assembly comprises a top cover sheet and a lower insulating member, wherein the top cover sheet is connected to the shell and covers the accommodating cavity; the lower insulating member is arranged between the top cover sheet and the electrode assembly, and is respectively connected to the top cover sheet and the lower insulating member; a pressure relief member is arranged on the top cover sheet, and the lower insulating member has a second groove, which is arranged on the side of the lower insulating member facing the electrode assembly, and the second groove is connected to the accommodating cavity; the second groove has a second bottom wall, which is spaced apart from the pressure relief member along the direction of the lower insulating member toward the top cover sheet, and the second bottom wall is configured to explode when the internal pressure of the secondary battery reaches a threshold value, so that the internal pressure of the secondary battery directly acts on the pressure relief member.

[0008] In some embodiments, the lower insulating member is provided with a first slit, the first slit is arranged on the second bottom wall, and the first slit penetrates the second bottom wall along a direction from the lower insulating member toward the top cover sheet.

[0009] In some embodiments, an orthographic projection of the pressure relief member on the lower insulating member is at least partially located on the second bottom wall and at least partially located in the first gap.

[0010] In some embodiments, the lower insulating member is provided with a plurality of the first slits, and the plurality of the first slits are arranged at intervals and are arranged around the edge of the second bottom wall.

[0011] In some embodiments, the lower insulating member is further provided with a third groove, and the third groove is arranged on a side of the second bottom wall facing the electrode assembly and is connected with the second groove.

[0012] In some embodiments, the third groove is disposed around the edge of the second bottom wall.

[0013] In some embodiments, the lower insulating member is provided with a first slit, the first slit is arranged on the second bottom wall, and the first slit penetrates the second bottom wall along the direction of the lower insulating member toward the top cover sheet, and the third groove is connected to the first slit.

[0014] In some embodiments, the third groove has a third bottom wall, the first slit is arranged on the third bottom wall, the third bottom wall forms at least a portion of the second bottom wall, and the first slit penetrates the third bottom wall along the direction of the lower insulating member toward the top cover sheet.

[0015] In some embodiments, the lower insulating member is provided with a plurality of the third grooves, and the lower insulating member is provided with a first slit, the first slit passes through the second bottom wall, the first slit is arranged between two adjacent third grooves, and is respectively connected to the two third grooves.

[0016] In some embodiments, the lower insulating member is provided with a plurality of the third grooves, and two adjacent third grooves intersect and communicate with each other.

[0017] In some embodiments, the length dimension of the first slit is L2 mm, and the width dimension of the first slit is W1 mm; a connecting portion is provided between two adjacent first slits, and the dimension of the connecting portion along the circumference of the second bottom wall is L1 mm; satisfying:

[0018] 0.1≤L1≤5;

[0019] 0.5≤L2≤20;

[0020] 0.1≤W1≤5.

[0021] In some embodiments, along the direction from the lower insulating member toward the top cover sheet, the size of the third bottom wall is H3 mm, and the size of the second bottom wall is H4 mm, satisfying: 0.02≤H3 / H4≤0.8; wherein, 0.1≤H3≤4, 0.5≤H4≤5.

[0022] In some embodiments, the lower insulating member has a first groove, which is arranged on the side of the lower insulating member facing the top cover sheet, and the first groove has a first bottom wall, and the orthographic projection of the pressure relief member on the lower insulating member is located in the first groove, so that the pressure relief member and the lower insulating member are spaced apart; the second groove is arranged on the side of the first bottom wall facing the electrode assembly, and the second bottom wall forms at least a part of the first bottom wall.

[0023] In some embodiments, along the direction of the lower insulating member toward the top cover sheet, the depth of the second groove is H1 mm, the distance between the side of the first bottom wall facing the electrode assembly and the top cover sheet is H2 mm, and the lower insulating member satisfies: 0.01≤H1 / H2≤0.8; wherein, 0.01≤H1≤12, and / or, 1≤H2≤15.

[0024] Accordingly, a battery pack described in an embodiment of the present application includes a secondary battery as described in any one of the aforementioned embodiments.

[0025] Accordingly, an electrical device described in an embodiment of the present application includes a secondary battery as described in any one of the aforementioned embodiments, or a battery pack as described in the aforementioned embodiments.

[0026] Beneficial effect: Compared with the prior art, a secondary battery in an embodiment of the present application includes a shell, an electrode assembly and a top cover assembly, the shell having a accommodating cavity, and the electrode assembly is arranged in the accommodating cavity; the top cover assembly includes a top cover sheet and a lower insulating member, the top cover sheet is connected to the shell and covers the accommodating cavity; the lower insulating member is arranged between the top cover sheet and the electrode assembly, and is respectively connected to the top cover sheet and the lower insulating member; a pressure relief member is arranged on the top cover sheet, the lower insulating member has a second groove, the second groove is arranged on the side of the lower insulating member facing the electrode assembly, and the second groove is connected to the accommodating cavity; the second groove has a second bottom wall, and the second bottom wall is spaced apart from the pressure relief member along the direction of the lower insulating member toward the top cover sheet, and the second bottom wall is configured to explode when the internal pressure of the secondary battery reaches a threshold value, so that the internal pressure of the secondary battery directly acts on the pressure relief member. The present application provides a second groove on the lower insulating member with an opening toward the electrode assembly, and the second groove has a second bottom wall. The second bottom wall can burst open when the secondary battery thermally runs away and the internal pressure reaches a threshold value, so that the internal pressure directly acts on the pressure relief member to realize the opening and pressure relief of the pressure relief member, replacing the prior art of providing a through hole on the lower insulating member to allow the thermal runaway gas to pass through and open the pressure relief member, greatly reducing the area of ​​the top cover sheet exposed to metal, thereby greatly reducing the risk of internal short circuit in the secondary battery; wherein, the second bottom wall is spaced apart from the pressure relief member, which can provide space for the second bottom wall to burst open, thereby facilitating the internal pressure of the secondary battery to directly act on the pressure relief member; in addition, the provision of the second groove enables the second bottom wall to be spaced apart from the electrode assembly, which facilitates the gas to gather to the second groove and act on the second bottom wall when the battery thermally runs away, which is more conducive to the bursting of the second bottom wall, and can also avoid the electrode assembly from contacting the second bottom wall under vibration conditions to cause the second bottom wall to rupture, thereby ensuring the safety of the secondary battery during normal operation.

[0027] Compared with the prior art, a battery pack according to an embodiment of the present application includes a secondary battery according to any one of the aforementioned embodiments. It is understandable that the battery pack has all the technical features and technical effects of the aforementioned secondary batteries, which will not be described in detail here.

[0028] Compared with the prior art, an electric device in an embodiment of the present application includes a secondary battery as in any one of the aforementioned embodiments, or a battery pack as in the aforementioned embodiments. It is understandable that the electric device has all the technical features and technical effects of the aforementioned secondary battery or battery pack, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 is a schematic diagram of the overall structure of a secondary battery in an embodiment of the present application;

[0031] Figure 2 It is a schematic diagram of the overall structure of a top cover assembly in which a plurality of first gaps are arranged around a second bottom wall according to an embodiment of the present application;

[0032] Figure 3 yes Figure 2 A top view of

[0033] Figure 4 yes Figure 3 A magnified view of part A;

[0034] Figure 5 yes Figure 3 Sectional view of section AA;

[0035] Figure 6 yes Figure 5 A magnified view of part B;

[0036] Figure 7 This is a schematic diagram of the overall structure of a top cover assembly in which a first slit is arranged in the middle of a second bottom wall in an embodiment of the present application;

[0037] Figure 8 yes Figure 7 A top view of

[0038] Fig. 9 yes Figure 8 Sectional view of the middle BB section;

[0039] Fig.10 yes Figure 8 Enlarged view of part C;

[0040] Fig.11 It is a schematic diagram of the overall structure of a top cover assembly in which a third groove is arranged on the second bottom wall of an embodiment of the present application;

[0041] Fig.12 yes Fig.11 A top view of

[0042] Fig.13 yes Fig.12 Sectional view of the CC section;

[0043] Fig.14 It is a schematic diagram of the overall structure of a top cover assembly in an embodiment of the present application in which a first gap and a third groove are provided at the same time;

[0044] Fig.15 yes Fig.14 A top view of

[0045] Fig.16 yes Fig.15Cross-sectional view of the middle DD section;

[0046] Fig.17 It is a schematic diagram of the overall structure of a top cover assembly in which third grooves are respectively provided at both ends of a first slit in an embodiment of the present application;

[0047] Fig.18 yes Fig.17 A top view of

[0048] Fig.19 yes Fig.18 Cross-sectional view of section EE;

[0049] Fig. 20 It is a schematic diagram of the overall structure of another top cover assembly in which third grooves are respectively provided at both ends of the first slit according to an embodiment of the present application;

[0050] Fig.21 yes Fig. 20 A top view of

[0051] Fig. 22 yes Fig.21 Cross-sectional view of the FF section;

[0052] Fig.23 yes Fig. 22 A magnified view of part D in the middle;

[0053] Fig.24 It is a schematic diagram of the overall structure of a top cover assembly in which a plurality of third grooves are combined into a network according to an embodiment of the present application;

[0054] Fig.25 yes Fig.24 A top view of

[0055] Fig.26 yes Fig.25 Cross-sectional view of section GG.

[0056] Figure numerals: 1, shell; 11, accommodating chamber; 2, electrode assembly; 3, top cover assembly; 31, top cover sheet; 311, pressure relief member; 32, lower insulating member; 321, first groove; 3211, first bottom wall; 322, second groove; 3221, second bottom wall; 323, first gap; 324, third groove; 3241, third bottom wall; 325, connecting part; 326, main body; 3261, exhaust hole. DETAILED DESCRIPTION

[0057] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0058] In the description of the present application, it should be understood that the terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, "multiple" means two or more, and at least one means one, two or more, unless otherwise clearly and specifically defined. In the description of this application, "vertical" means completely vertical at 90° or almost completely vertical, for example, an angle within the range of 80° to 100° is considered vertical. Similarly, "parallel" means completely parallel or almost completely parallel, for example, an angle within 10° of completely parallel is considered parallel.

[0059] New energy will also gradually replace traditional environmentally polluting energy. As a representative of new energy, power batteries have gradually been recognized by manufacturers and consumers. As the main power source of new energy vehicles, secondary batteries have become one of the key components of electric vehicles. As a key component of secondary batteries, the top cover assembly has a significant impact on the energy density, economy and safety of secondary batteries. The top cover assembly is provided with a pressure relief part (explosion-proof valve) to open and release the internal pressure in time when the internal pressure increases sharply due to abnormal gas production of the secondary battery, so as to prevent the explosion of the secondary battery. In addition, in order to protect the pressure relief part (explosion-proof valve) from the influence of the internal parts of the secondary battery, the current mainstream design is to set a boss feature in the area of ​​the lower insulating part (lower plastic) corresponding to the explosion-proof valve to separate the explosion-proof valve and the electrode assembly, so as to avoid mechanical damage to the explosion-proof valve caused by the winding core under the working condition vibration, or interference between the pole piece and the explosion-proof valve, resulting in internal short; at the same time, in order not to affect the exhaust and pressure relief function of the explosion-proof valve, an exhaust through hole feature is set on the boss of the lower plastic to ensure that the gas produced in the secondary battery can pass smoothly and act on the explosion-proof valve. However, foreign metal matter inside the secondary battery may overlap with the pressure relief component through the through-hole feature, causing an internal short circuit, thereby creating the risk of corrosion and cracking of the pressure relief component.

[0060] In view of this, an embodiment of the present application provides a secondary battery, aiming to solve the above technical problems.

[0061] Please refer to Figure 1 , Figure 2 , Figure 5 and Figure 6 The embodiment of the present application provides a secondary battery, including a shell 1, an electrode assembly 2 and a top cover assembly 3, wherein the shell 1 has a receiving cavity 11, and the electrode assembly 2 is arranged in the receiving cavity 11; the top cover assembly 3 includes a top cover sheet 31 and a lower insulating member 32, the top cover sheet 31 is connected to the shell 1 and covers the receiving cavity 11; the lower insulating member 32 is arranged between the top cover sheet 31 and the electrode assembly 2, and is respectively connected to the top cover sheet 31 and the lower insulating member 32; a pressure relief member 311 is arranged on the top cover sheet 31, and the lower insulating member 32 is provided with a pressure relief member 312. The second groove 322 is provided on the side of the lower insulating member 32 facing the electrode assembly 2, and the second groove 322 is communicated with the accommodating chamber 11; the second groove 322 has a second bottom wall 3221, which is arranged along the direction from the lower insulating member 32 to the top cover sheet 31, and the second bottom wall 3221 is spaced apart from the pressure relief member 311, and the second bottom wall 3221 is configured to explode when the internal pressure of the secondary battery reaches a threshold value, so that the internal pressure of the secondary battery directly acts on the pressure relief member 311.

[0062] In the embodiment of the present application, a second groove 322 is provided on the lower insulating member 32, and the second groove 322 has a second bottom wall 3221. The second bottom wall 3221 can explode when the secondary battery thermally runs away and the internal pressure reaches a threshold value, so that the internal pressure directly acts on the pressure relief member 311, and the pressure relief member 311 is opened to relieve pressure, which replaces the prior art of providing a through hole on the lower insulating member 32 to allow the thermal runaway gas to pass through and open the pressure relief member 311, greatly reducing the area of ​​the top cover sheet 31 exposed to metal, thereby greatly reducing the risk of internal short circuit of the secondary battery; wherein, the second bottom wall 3221 can explode when the internal pressure reaches a threshold value due to thermal runaway of the secondary battery, so that the internal pressure directly acts on the pressure relief member 311, and the pressure relief member 311 is opened to relieve pressure. The wall 3221 is spaced apart from the pressure relief piece 311, which can provide space for the second bottom wall 3221 to burst, thereby facilitating the internal pressure of the secondary battery to act directly on the pressure relief piece 311; in addition, the second groove 322 is provided to achieve the spacing of the second bottom wall 3221 and the electrode assembly 2, which makes it convenient for gas to gather in the second groove 322 and act on the second bottom wall 3221 when the battery thermal runaway occurs, which is more conducive to the second bottom wall 3221 bursting, and can also prevent the electrode assembly 2 from contacting the second bottom wall 3221 under vibration conditions, causing the second bottom wall 3221 to rupture, thereby ensuring the safety of the secondary battery during normal operation.

[0063] Specifically, in the embodiment of the present application, the lower insulating member 32 can be a plastic member formed by a process such as injection molding, which can achieve a better insulation effect. The lower insulating member 32 is connected to the top cover sheet 31 to ensure that the lower insulating member 32 is fixed in the accommodating cavity 11 of the shell 1. At the same time, the lower insulating member 32 is connected to the electrode assembly 2. Specifically, the local position of the lower insulating member 32 can be in contact with the electrode assembly 2 to ensure that the electrode assembly 2 is fixed in the accommodating cavity 11, thereby reducing the movement of the electrode assembly 2 in the shell 1 under vibration conditions, thereby effectively avoiding abnormalities such as broken connection between the pole ear and the pole.

[0064] It can be understood that the second bottom wall 3221 of the second groove 322 of the embodiment of the present application is configured to burst when the internal pressure of the secondary battery reaches a threshold value, so that the internal pressure of the secondary battery directly acts on the pressure relief member 311. At this time, the corresponding second bottom wall 3221 is relatively thinner than other areas of the lower insulating member 32, so that it can burst when the internal pressure is high.

[0065] It should be noted that the second groove 322 of the embodiment of the present application is arranged on the side of the lower insulating member 32 facing the electrode assembly 2. At this time, it can be understood that the opening of the second groove 322 faces the electrode assembly 2. Then the corresponding second bottom wall 3221 of the second groove 322 is arranged opposite to the notch of the second groove 322. At this time, the second bottom wall 3221 will be spaced apart from the electrode assembly 2. In this way, when the secondary battery is in a vibrating condition, even if the electrode assembly 2 vibrates, it will only contact the notch of the second groove 322, and will not contact the second bottom wall 3221. In this way, the structural integrity of the second bottom wall 3221 can be effectively guaranteed when the secondary battery is operating normally, so that the second bottom wall 3221 can be effectively isolated from metal foreign matter in the battery through the second bottom wall 3221, thereby effectively avoiding the occurrence of internal short circuit of the secondary battery.

[0066] It should also be noted that in the embodiment of the present application, along the direction of the lower insulating member 32 toward the top cover piece 31, the second bottom wall 3221 and the pressure relief member 311 are spaced apart. At this time, it can be understood that there is a gap space between the second bottom wall 3221 and the pressure relief member 311, which can provide a bursting space for the second bottom wall 3221, thereby facilitating the internal pressure to directly act on the pressure relief member 311 to achieve rapid pressure relief.

[0067] It is also necessary to note that, please refer to Fig. 9 In the embodiment of the present application, the lower insulating member 32 may include a body 326, the body 326 has an exhaust hole 3261, the second bottom wall 3221 is connected to the hole wall of the exhaust hole 3261, and the second bottom wall 3221 is spaced from the top cover sheet 31 and the electrode assembly 2 along the direction of the lower insulating member 32 toward the top cover sheet 31, and the hole wall of the exhaust hole 3261 and the second bottom wall 3221 form a second groove 322, so that the top cover sheet 31 is effectively isolated from the electrode assembly 2 and the metal foreign matter through the body 326 and the second bottom wall 3221 of the lower insulating member 32; and the second bottom wall 3221 can be exploded toward the top cover sheet 31 so that the internal pressure of the battery directly acts on the pressure relief member 311, so that the pressure relief member 311 can quickly open and release pressure; at the same time, the second bottom wall 3221 can be prevented from directly contacting the electrode assembly 2, ensuring that the second bottom wall 3221 is structurally stable under vibration conditions, and avoiding the situation where the second bottom wall 3221 is damaged and the risk of internal short circuit of the battery is increased.

[0068] Please refer to Figure 2-Figure 10 , Fig.14 , Fig.15 , Fig.17 , Fig.18 , Figure 20-Figure 22 In some embodiments, the lower insulating member 32 is provided with a first slit 323 , the first slit 323 is disposed on the second bottom wall 3221 , and the first slit 323 penetrates the second bottom wall 3221 along a direction from the lower insulating member 32 toward the top cover sheet 31 .

[0069] In the embodiment of the present application, by providing the first gap 323, it is easier to break open the second bottom wall 3221 when abnormal gas production and internal pressure increase inside the secondary battery, thereby achieving rapid explosion of the second bottom wall 3221, thereby facilitating rapid opening of the pressure relief member 311 for pressure relief, thereby improving the safety of the entire battery pack.

[0070] Specifically, in the embodiment of the present application, a first slit 323 is provided on the second bottom wall 3221. At this time, the thermal runaway gas in the battery preferentially passes through the first slit 323 and flows to the gap between the pressure relief piece 311 and the second bottom wall 3221. Since the internal pressure of the battery is too high, the high-pressure thermal runaway gas can impact the second bottom walls 3221 on both sides of the first slit 323 toward the top cover sheet 31 and cause the second bottom wall 3221 to deform and explode toward the top cover sheet 31, thereby enabling the thermal runaway gas to act on the pressure relief piece 311 more quickly, thereby achieving rapid opening of the pressure relief piece 311.

[0071] It should be noted that the width of the first gap 323 in the embodiment of the present application is relatively small, so that less metal is exposed on the top cover sheet 31 and it can play a role in blocking metal foreign matter. While making the second bottom wall 3221 easier to burst open, it reduces the possibility of metal foreign matter passing through and causing an internal short circuit in the secondary battery.

[0072] In some embodiments, the orthographic projection of the pressure relief member 311 on the lower insulating member 32 is at least partially located on the second bottom wall 3221 , and at least partially located in the first slit 323 .

[0073] It is understandable that in the embodiment of the present application, along the direction from the lower insulating member 32 to the top cover sheet 31, the pressure relief member 311 is arranged opposite to the second bottom wall 3221, and further, the pressure relief member 311 is arranged opposite to the first gap 323. At this time, the high-pressure thermal runaway gas can directly act on the pressure relief member 311 after the second bottom wall 3221 explodes, so that the pressure relief member 311 can be quickly opened to release pressure. In addition, with this structural setting, when the distance between the pressure relief member 311 and the second bottom wall 3221 allows, the second bottom wall 3221 can directly act on the pressure relief member 311 when it explodes, and the second bottom wall 3221 directly contacts the pressure relief member 311, causing an impact on the pressure relief member 311, thereby rupturing the weak area of ​​the pressure relief member 311, and enabling the pressure relief member 311 to be opened and released more quickly.

[0074] Please refer to Figure 2-Figure 4 In some embodiments, the lower insulating member 32 is provided with a plurality of first slits 323 , and the plurality of first slits 323 are arranged at intervals and are disposed around the edge of the second bottom wall 3221 .

[0075] In the embodiment of the present application, the plurality of first slits 323 are arranged at intervals, which makes it easier for the second bottom wall 3221 to burst open more quickly when impacted by the internal pressure, thereby making it easier for the pressure relief member 311 to open quickly to relieve pressure.

[0076] Specifically, it can be understood that the plurality of first slits 323 are arranged at intervals, and a connecting portion 325 is provided between two adjacent first slits 323 to separate the two adjacent first slits 323. The connecting portion 325 has a relatively small area and is more easily broken when subjected to the high pressure impact inside the battery, thereby enabling the internal pressure of the battery to act on the pressure relief member 311 more quickly, making it easier for the pressure relief member 311 to open and relieve pressure.

[0077] More specifically, the second bottom wall 3221 can be connected to the hole wall of the exhaust hole 3261 through the connecting portion 325. At this time, the connecting portion 325 between the second bottom wall 3221 and the hole wall of the exhaust hole 3261 is relatively small. When impacted by thermal runaway gas, the connecting portion 325 can break quickly to realize the rapid explosion of the second bottom wall 3221, thereby facilitating the rapid opening of the pressure relief piece 311 to relieve pressure.

[0078] Please refer to Figure 11-Figure 25 In some embodiments, the lower insulating member 32 is further provided with a third groove 324 , which is disposed on a side of the second bottom wall 3221 facing the electrode assembly 2 and is connected to the second groove 322 .

[0079] In the embodiment of the present application, the third groove 324 is arranged on the second bottom wall 3221. At this time, the third groove 324 has a third bottom wall 3241. The third bottom wall 3241 is thinner than the second bottom wall 3221, which is equivalent to a weak area on the second bottom wall 3221. When the internal thermal runaway of the secondary battery causes the internal pressure to increase, the internal pressure acts on the second bottom wall 3221, and the second bottom wall 3221 starts to break from the third bottom wall 3241 of the third groove 324, thereby realizing the rapid explosion of the second bottom wall 3221, thereby realizing the rapid opening and pressure relief of the pressure relief piece 311.

[0080] It should be noted that the embodiment of the present application forms a weak area on the second bottom wall 3221 by setting a third groove 324, which facilitates the second bottom wall 3221 to burst open. At this time, the second bottom wall 3221 completely closes the exhaust hole 3261, which can completely isolate metal foreign matter and prevent the metal foreign matter from contacting the top cover sheet 31 and causing a short circuit.

[0081] Please refer to Fig.11 , Fig.12 , Fig.14 , Fig.15 , Fig.17 , Fig.18 , Fig. 20 and Fig.21In some embodiments, the third groove 324 is disposed around the edge of the second bottom wall 3221 .

[0082] In the embodiment of the present application, the third groove 324 is arranged around the edge of the second bottom wall 3221 . In this case, the third groove 324 can have a larger distribution area, which makes it easier to explode the second bottom wall 3221 .

[0083] Please refer to Fig.14 , Fig.15 , Fig.17 , Fig.18 , Fig. 20 and Fig.21 In some embodiments, the lower insulating member 32 is provided with a first slit 323 , the first slit 323 is arranged on the second bottom wall 3221 , and the first slit 323 penetrates the second bottom wall 3221 along the direction of the lower insulating member 32 toward the top cover sheet 31 , and the third groove 324 is connected to the first slit 323 .

[0084] In the embodiment of the present application, by designing the third groove 324 to cooperate with the first gap 323 , the second bottom wall 3221 can be further quickly opened on the basis of a small exposed metal area of ​​the top cover sheet 31 , thereby achieving rapid opening and pressure relief of the pressure relief member 311 .

[0085] Specifically, in the embodiment of the present application, the first slit 323 is provided to provide an opening for the second bottom wall 3221 to burst open, and the third groove 324 can provide a weak area for the second bottom wall 3221 to facilitate the bursting of the second bottom wall 3221. At the same time, the first slit 323 is connected to the third groove 324, which is equivalent to the first slit 323 opening to stretch open the bottom wall of the third groove 324, thereby reducing the difficulty of the second bottom wall 3221 bursting open.

[0086] Please refer to Fig.12 , Fig.15 and Fig.18 In some embodiments, the third groove 324 has a third bottom wall 3241, the third bottom wall 3241 forms at least a portion of the second bottom wall 3221, the first slit 323 is disposed on the third bottom wall 3241, and the first slit 323 penetrates the third bottom wall 3241 along the direction from the lower insulating member 32 toward the top cover sheet 31.

[0087] In the embodiment of the present application, the first gap 323 is directly set on the third bottom wall 3241 of the third groove 324. At this time, the high-pressure gas directly acts on the third bottom wall 3241 when it opens the first gap 323, and opens the third bottom wall 3241, thereby achieving rapid rupture of the third bottom wall 3241, which is more conducive to the explosion of the second bottom wall 3221, and is more conducive to the rapid opening and pressure relief of the pressure relief piece 311.

[0088] Please refer to Fig.11 , Fig.18 , Fig. 20 and Fig.21 In some embodiments, the lower insulating member 32 is provided with a plurality of third grooves 324 , and the lower insulating member 32 is provided with a first slit 323 , the first slit 323 passes through the second bottom wall 3221 , and the first slit 323 is arranged between two adjacent third grooves 324 and is connected to the two third grooves 324 respectively.

[0089] In the embodiment of the present application, a plurality of third grooves 324 are provided to cooperate with the first slit 323 to provide more breakthroughs for the second bottom wall 3221 to burst open, thereby further realizing the rapid burst open of the second bottom wall 3221 .

[0090] Please refer to Figure 24-26 In some embodiments, the lower insulating member 32 is provided with a plurality of third grooves 324 , and two adjacent third grooves 324 intersect and communicate with each other.

[0091] In the embodiment of the present application, multiple third grooves 324 intersect and are connected in pairs. At this time, not only the top cover sheet 31 and the electrode assembly 2 are supported, and the metal foreign matter and the top cover sheet 31 are prevented from overlapping and short-circuiting, but also multiple weak areas are provided for the second bottom wall 3221. When the battery is thermally runaway, more explosion areas are provided for the second bottom wall 3221, thereby realizing a faster explosion of the second bottom wall 3221.

[0092] See also Figure 4 In some embodiments, the length dimension of the first slit 323 is L2 mm, and the width dimension of the first slit 323 is W1 mm; a connecting portion 325 is provided between two adjacent first slits 323, and the dimension of the connecting portion 325 along the circumference of the second bottom wall 3221 is L1 mm; satisfying:

[0093] 0.1≤L1≤5;

[0094] 0.5≤L2≤20;

[0095] 0.1≤W1≤5.

[0096] In the embodiment of the present application, by controlling the size of the first gap and the connecting portion 325 within the above-mentioned range, it is possible to ensure that the overall processing difficulty of the lower insulating member 32 is not too high, and at the same time, the qualified rate of the finished product of the lower insulating member 32 can be ensured, thereby avoiding the problem of increased production difficulty and too low structural strength of the connecting portion 325 due to the first gap 323 being too narrow or the connecting portion 325 being too narrow and too long.

[0097] It should be noted that the numerical range of L1 can be any value in the range of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, or any two values. The numerical range of L2 can be any value in the range of 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18, 20, or any two values. The numerical range of W1 can be any value in the range of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, or any two values. If the size of the connection part 325 is too small, the connection part 325 is prone to breakage and internal shorting; if the size of the connection part 325 is too large, the overall strength of the connection part 325 is prone to be too high, which is not conducive to the breakage of the connection part 325, and then the second bottom wall 3221 may not be able to explode smoothly. Therefore, controlling the size of the first gap and the connection part 325 within the above range can not only realize the smooth production of the lower insulating member 32, but also ensure that the second bottom wall 3221 does not have too low structural strength to achieve the effect of blocking metal foreign matter, and at the same time ensure that the second bottom wall 3221 can be smoothly exploded when the secondary battery is thermally runaway, so that the high pressure inside the battery caused by the high-temperature gas generated by the thermal runaway of the battery directly acts on the pressure relief member 311.

[0098] See also Fig.23 In some embodiments, along the direction from the lower insulating member 32 toward the top cover sheet 31, the size of the third bottom wall 3241 is H3 mm, and the size of the second bottom wall 3221 is H4 mm, satisfying: 0.02≤H3 / H4≤0.8; wherein, 0.1≤H3≤4, 0.5≤H4≤5.

[0099] In the embodiment of the present application, by controlling the second bottom wall 3221 and the third bottom wall 3241 to satisfy: 0.02≤H3 / H4≤0.8; wherein, 0.1≤H3≤4, 0.5≤H4≤5, the third bottom wall 3241 can be made thinner than the second bottom wall 3221, which is more conducive to rapid rupture of the third bottom wall 3241 when the secondary battery has thermal runaway, thereby achieving rapid explosion of the second bottom wall 3221, and the higher internal pressure generated by thermal runaway directly acts on the pressure relief member 311.

[0100] It should be noted that the numerical range of H3 / H4 can be any one of 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, or the range between any two values. Among them, the numerical range of H3 can be any one of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, or the range between any two values. The numerical range of H4 can be any one of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, and 5, or a range between any two values. If the numerical value is too small, the processing difficulty of the lower insulating member 32 is large, the yield rate is reduced, and the production process cost is increased; if the numerical value is too small, the third groove 324 and the corresponding third bottom wall 3241 cannot play the function of assisting the second bottom wall 3221 to explode.

[0101] Please refer to Figure 5 , Figure 6 , Fig. 9 , Fig.13 , Fig.16 , Fig.19 , Fig. 22 , Fig.23 and Fig.26 In some embodiments, the lower insulating member 32 has a first groove 321, which is disposed on the side of the lower insulating member 32 facing the top cover sheet 31, and has a first bottom wall 3211. The positive projection of the pressure relief member 311 on the lower insulating member 32 is located in the first groove 321, so that the pressure relief member 311 and the lower insulating member 32 are spaced apart; the second groove 322 is disposed on the side of the first bottom wall 3211 facing the electrode assembly 2, and the second bottom wall 3221 forms at least part of the first bottom wall 3211. A first slit 323 may also be disposed on the second bottom wall 3221, and the second groove 322 is connected to the first groove 321 through the first slit 323.

[0102] In the embodiment of the present application, the opening of the first groove 321 is set toward the top cover sheet 31, and the first bottom wall 3211 of the first groove 321 is spaced apart from the top cover sheet 31; further, the positive projection of the pressure relief member 311 on the lower insulating member 32 is located in the first groove 321, and the first bottom wall 3211 is spaced apart from the pressure relief member 311; the second groove 322 is set on the side of the first bottom wall 3211 facing the electrode assembly 2, and the second bottom wall 3221 forms at least part of the first bottom wall 3211, so that the pressure relief member 311 and the second bottom wall 3221 are spaced apart; in this way, the first groove 321 is used to realize the spacing of the second bottom wall 3221 and the pressure relief member 311, and the second bottom wall 3221 can explode into the first groove 321 when the internal pressure of the battery reaches the explosion threshold, providing space for the second bottom wall 3221 to explode. At the same time, the structure around the notch of the first groove 321 can be connected to the top cover sheet 31 to achieve the stability of the structure of the top cover assembly 3.

[0103] See also Figure 6 In some embodiments, along the direction of the lower insulating member 32 toward the top cover sheet 31, the depth of the second groove 322 is H1 mm, the distance between the first bottom wall 3211 and the side facing the electrode assembly 2 and the top cover sheet 31 is H2 mm, and the lower insulating member 32 satisfies: 0.01≤H1 / H2≤0.8; wherein, 0.01≤H1≤12, and / or, 1≤H2≤15.

[0104] In the embodiment of the present application, by setting 0.01≤H1 / H2≤0.8, on the one hand, it is ensured that there is a suitable distance between the second bottom wall 3221 and the electrode assembly 2, so as to avoid the second bottom wall 3221 from contacting the electrode assembly 2 under vibration conditions, thereby avoiding the second bottom wall 3221 from being directly hit by the electrode assembly 2 and causing mechanical damage. On the other hand, it is more conducive to the thermal runaway gas to gather in the second groove 322 and act on the second bottom wall 3221, so as to achieve the rapid explosion of the second bottom wall 3221. At the same time, it can also avoid the second bottom wall 3221 from directly contacting the pressure relief member 311 under vibration conditions, causing mechanical damage to the pressure relief member 311, and avoiding the overall destruction of the battery.

[0105] It should be noted that the numerical range of H1 / H2 can be any one of 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, or the range between any two values. Among them, the numerical range of H1 can be any one of 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.5, 1, 1.5, 2, 3, 4, 5, 8, 10, 12, or the range between any two values. The numerical range of H2 can be any value of 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.5, 3, 3.5, 4, 5, 6, 7, 8, 9, 10, 12, 15, or the range between any two values.

[0106] It should be noted that if the ratio of H1 / H2 is too small, the second bottom wall 3221 is likely to contact with the electrode assembly 2 and be damaged by the electrode assembly 2 under vibration conditions, resulting in a large exposed metal area of ​​the top cover sheet 31, which may easily cause an internal short circuit in the battery; if the ratio of H1 / H2 is too large, under vibration conditions, although the second bottom wall 3221 is not easy to contact with the electrode assembly 2, the second bottom wall 3221 is likely to directly contact with the pressure relief member 311, causing mechanical damage to the pressure relief member 311, thereby causing battery failure.

[0107] It should also be noted that in the above embodiments, some commonly used dimension measurement methods can be selected to measure any one of the dimensions H1, H2, H3, H4, L1, L2, and W1. For example, a ruler, a micrometer, a vernier caliper, or other measuring tools can be used to measure the corresponding dimensions. Alternatively, a projection method can be used to measure, using a projection measurement device (such as a digital microscope or an image measuring instrument) to obtain images of the first gap and the connecting portion and measure the corresponding dimensions.

[0108] The secondary battery of the present application is described in detail below with reference to specific embodiments.

[0109] Table 1

[0110]

[0111] Table 2

[0112]

[0113]

[0114] Table 3

[0115]

[0116] Please refer to Table 1, Table 2 and Table 3. It can be seen from the above embodiments and comparative examples that when H1 and H2 satisfy: 0.01≤H1 / H2≤0.8, where 0.01≤H1≤12, and / or 1≤H2≤15, under vibration conditions, the second bottom wall 3221 will neither contact the electrode assembly 2 nor the pressure relief member 311. At this time, when the secondary battery is working normally, it can be ensured that the second bottom wall 3221 and the pressure relief member 311 will not be mechanically damaged. When H1 and / or H2 are outside the above range, the second bottom wall 3221 will either contact the electrode assembly 2 or the pressure relief member 311 under vibration conditions, which will have a significant impact on the safety of the secondary battery, causing the secondary battery to be unable to be used normally. When H3 and H4 meet: 0.02≤H3 / H4≤0.8, among which 0.1≤H3≤4, 0.5≤H4≤5, the third bottom wall 3241 can be successfully destroyed and exploded, and then the second bottom wall 3221 can be successfully exploded, so that the pressure inside the secondary battery reaches the threshold value. If the value is too small, the processing difficulty of the lower insulating part 32 increases, and it may even be impossible to process and form; if the value is too large, it is difficult for the third bottom wall 3241 to explode, which will affect the smooth pressure release when the secondary battery is in thermal runaway. When 0.1≤L1≤5, 0.5≤L2≤20, 0.1≤W1≤5, the lower insulating part 32 can be smoothly processed and formed, and the process difficulty is low. At the same time, the connecting part 325 can be destroyed when the internal pressure of the battery reaches the threshold value. If the value is too small, the processing difficulty of the lower insulating member 32 is large and the molding rate is low. If the value is too large, the strength of the connecting portion 325 is too high. When the internal pressure of the battery reaches the threshold, the second bottom wall 3221 cannot be opened smoothly, resulting in the obstruction of the exhaust and pressure relief of the pressure relief member 311. Therefore, when the secondary battery of the embodiment of the present application meets the conditions in the above table, the safety and reliability of the secondary battery can be significantly improved.

[0117] Accordingly, a battery pack according to an embodiment of the present application includes a secondary battery as described in any one of the above embodiments. It is understandable that the battery pack according to the embodiment of the present application includes all the technical features and technical effects of the above secondary batteries, which will not be described in detail here.

[0118] Accordingly, an electric device according to an embodiment of the present application includes a secondary battery as described in any one of the above embodiments, or a battery pack as described in the above embodiments. It is understandable that the electric device according to the embodiment of the present application includes all the technical features and technical effects of the above secondary battery or battery pack, which will not be repeated here.

[0119] Of course, the electrical devices referred to in this application may be application devices such as vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys and electric tools. Vehicles may be new energy vehicles, which may be pure electric vehicles, hybrid electric vehicles or extended-range vehicles, etc.; spacecraft include airplanes, rockets, space shuttles and spacecrafts, etc.; electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc.; electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers, etc. The embodiments of this application do not impose any special restrictions on the above-mentioned electrical devices.

[0120] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0121] The above is a detailed introduction to a secondary battery, a battery pack and an electrical device provided in the embodiments of the present application, and specific examples are used to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of ​​the present application; ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present application.

Claims

1. A secondary battery, characterized in that: include: A housing having a receiving cavity; An electrode assembly, disposed in the accommodating cavity; A top cover assembly comprises a top cover sheet and a lower insulating member, wherein the top cover sheet is connected to the shell and covers the accommodating cavity; the lower insulating member is arranged between the top cover sheet and the electrode assembly, and is respectively connected to the top cover sheet and the electrode assembly; a pressure relief member is arranged on the top cover sheet, and the lower insulating member has a second groove, which is arranged on the side of the lower insulating member facing the electrode assembly, and the second groove is connected to the accommodating cavity; the second groove has a second bottom wall, which is spaced apart from the pressure relief member along the direction of the lower insulating member toward the top cover sheet, and the second bottom wall is configured to explode when the internal pressure of the secondary battery reaches a threshold value, so that the internal pressure of the secondary battery directly acts on the pressure relief member.

2. The secondary battery according to claim 1, characterized in that: The lower insulating member is provided with a first slit, the first slit is arranged on the second bottom wall, and the first slit penetrates the second bottom wall along a direction from the lower insulating member toward the top cover sheet.

3. The secondary battery according to claim 2, characterized in that: The orthographic projection of the pressure relief member on the lower insulating member is at least partially located on the second bottom wall, and at least partially located in the first gap.

4. The secondary battery according to claim 3, characterized in that: The lower insulating member is provided with a plurality of the first slits, and the plurality of the first slits are arranged at intervals and are arranged around the edge of the second bottom wall.

5. The secondary battery according to claim 1, characterized in that: The lower insulating member is further provided with a third groove, and the third groove is arranged on a side of the second bottom wall facing the electrode assembly and is communicated with the second groove.

6. The secondary battery according to claim 5, characterized in that: The third groove is disposed around the edge of the second bottom wall.

7. The secondary battery according to claim 6, characterized in that: The lower insulating member is provided with a first slit, the first slit is arranged on the second bottom wall, and the first slit penetrates the second bottom wall along the direction from the lower insulating member toward the top cover sheet, and the third groove is communicated with the first slit.

8. The secondary battery according to claim 7, characterized in that: The third groove has a third bottom wall, the third bottom wall forms at least a portion of the second bottom wall, the first slit is disposed on the third bottom wall, and the first slit penetrates the third bottom wall along a direction from the lower insulating member toward the top cover sheet.

9. The secondary battery according to claim 5, characterized in that: The lower insulating member is provided with a plurality of the third grooves. The lower insulating member is provided with a first slit. The first slit penetrates the second bottom wall. The first slit is arranged between two adjacent third grooves and is communicated with the two third grooves respectively.

10. The secondary battery according to claim 5, characterized in that: The lower insulating member is provided with a plurality of the third grooves, and two adjacent third grooves intersect and communicate with each other.

11. The secondary battery according to claim 4, characterized in that: The length dimension of the first slit is L2 mm, and the width dimension of the first slit is W1 mm; a connecting portion is provided between two adjacent first slits, and the dimension of the connecting portion along the circumference of the second bottom wall is L1 mm; satisfying: 0.1≤L1≤5； 0.5≤L2≤20； 0.1≤W1≤5。 12. The secondary battery according to claim 8, characterized in that: Along the direction from the lower insulating member to the top cover sheet, the size of the third bottom wall is H3 mm, and the size of the second bottom wall is H4 mm, satisfying: 0.02≤H3 / H4≤0.8; wherein, 0.1≤H3≤4, 0.5≤H4≤5.

13. The secondary battery according to claim 1, characterized in that: The lower insulating member has a first groove, which is arranged on the side of the lower insulating member facing the top cover sheet, and the first groove has a first bottom wall. The orthographic projection of the pressure relief member on the lower insulating member is located in the first groove, so that the pressure relief member and the lower insulating member are spaced apart; the second groove is arranged on the side of the first bottom wall facing the electrode assembly, and the second bottom wall forms at least a part of the first bottom wall.

14. The secondary battery according to claim 13, characterized in that: Along the direction from the lower insulating member to the top cover sheet, the depth of the second groove is H1 mm, the distance between the first bottom wall facing the side of the electrode assembly and the top cover sheet is H2 mm, and the lower insulating member satisfies: 0.01≤H1 / H2≤0.8; wherein, 0.01≤H1≤12, and / or, 1≤H2≤15.

15. A battery pack, characterized in that: Comprising the secondary battery as claimed in any one of claims 1 to 14.

16. An electrical device, characterized in that: It comprises the secondary battery as claimed in any one of claims 1 to 14, or the battery pack as claimed in claim 15.

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