Battery cell, battery, and electric device

Abstract

A battery cell (20), a battery (100), and an electrical device are disclosed, relating to the field of batteries. The battery cell (20) includes a housing (22), the housing (22) having a wall (221), the wall (221) including a weak portion (21), the weak portion (21) being configured to be destroyed when the battery cell (20) releases internal pressure. The outer surface of the wall (221) has a center point (2213). The maximum distance between the projection of the weak portion (21) on the outer surface of the wall (221) and the center point (2213) is a, and the minimum radial dimension of the outer surface of the wall (221) is A, satisfying: a≤0.4A. Radial refers to the direction passing through the center point. By making a≤0.4A, the weak portion (21) is located in a region of the wall (221) with relatively low stiffness. When the battery cell (20) releases internal pressure, this region undergoes large deformation under the action of gas, and the weak portion (21) located in this region is easily destroyed. Under the same detonation pressure, the thickness of the weak section (21) located in this area can be greater. When the battery cell (20) is in normal use, the weak section (21) has a stronger ability to resist external impacts, thereby reducing the risk of the weak section (21) being damaged prematurely.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese patent application filed on May 31, 2023, entitled “Battery Cell, Battery and Electrical Device” (application number: 2023106369146), the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of batteries, and more specifically, to a battery cell, a battery, and an electrical device. Background Technology

[0004] Batteries are widely used in the new energy field, such as in electric vehicles and new energy vehicles, which have become a new trend in the automotive industry. Batteries are equipped with pressure relief mechanisms to release internal pressure when it reaches the explosion pressure. However, these mechanisms often open prematurely, preventing them from functioning properly. Summary of the Invention

[0005] The purpose of this application is to provide a battery cell, a battery, and an electrical device, which aims to improve the problem in related technologies where the pressure relief mechanism often opens prematurely, resulting in the inability to achieve normal pressure relief function.

[0006] In a first aspect, embodiments of this application provide a battery cell, the battery cell including a casing, the casing having a wall portion, the wall portion including a weak portion, the weak portion being configured to be destroyed when the battery cell releases internal pressure, the outer surface of the wall portion having a center point; wherein, the maximum distance between the projection of the weak portion on the outer surface of the wall portion and the center point is a, the minimum radial dimension of the outer surface of the wall portion is A, both satisfying: a≤0.4A, the radial direction refers to the direction passing through the center point.

[0007] In the above technical solution, by ensuring that a ≤ 0.4A, meaning the maximum distance between the projection of the weak portion onto the outer surface of the wall and the center point of the outer surface of the wall is less than or equal to 0.4 times the minimum radial dimension of the outer surface of the wall, the weak portion is located in a first region of the wall with relatively low stiffness. The first region is a circular area with the center point of the outer surface of the wall as its center and a radius of 0.4 times the minimum radial dimension of the outer surface of the wall. The first region is close to the center of the wall and has relatively low stiffness, making it less resistant to deformation. When the battery cell releases internal pressure, the first region undergoes significant deformation under the action of gas, making the weak portion located there prone to deformation and failure. Therefore, under the same detonation pressure, the thickness of the weak portion located in the first region can be greater. This increases the weak portion's resistance to external impacts during normal use of the battery cell, reducing the risk of premature failure. Furthermore, a larger weak portion is easier to manufacture, requiring less precision from the manufacturing equipment.

[0008] As an optional technical solution in this application embodiment, the wall portion is provided with a groove, and the weak portion is formed at the bottom of the groove.

[0009] In the above technical solution, the weak part is formed by creating grooves on the wall, which is simple, convenient and low in cost.

[0010] As an optional technical solution in this application embodiment, the projection of the weak part on the outer surface of the wall passes through the center point.

[0011] In the above technical solution, when the internal pressure of a battery cell is released, the center point is the location of the greatest deformation on the wall, and it is most easily damaged. By making the projection of the weak part on the outer surface of the wall pass through the center point, the thickness of the weak part at the center point can be increased. This makes the weak part more resistant to external impacts during normal use of the battery cell, thereby reducing the risk of premature damage to the weak part.

[0012] As an optional technical solution in this application embodiment, the weak part has a weak point corresponding to the center point, the thickness of the weak part at the weak point is a first thickness, and the maximum thickness of the weak part at other positions besides the weak point is a second thickness, wherein the first thickness is greater than or equal to the second thickness.

[0013] In the above technical solution, the first thickness is greater than the second thickness, meaning the thickness of the weak part at the weak point is greater than the maximum thickness at other locations on the weak part. The weak point is thicker than other locations, making it more resistant to external impacts and reducing the risk of premature failure. Alternatively, the first thickness can be equal to the second thickness, meaning the thickness of the weak part at the weak point is equal to the maximum thickness at other locations on the weak part. This results in a more uniform thickness for the weak part, facilitating manufacturing.

[0014] As an optional technical solution in this application embodiment, the groove includes at least one groove segment, the weak part includes at least one weak segment, and the at least one groove segment and the at least one weak segment are provided in a one-to-one correspondence.

[0015] In the above technical solution, each groove segment on the wall corresponds to a weak segment. During manufacturing, it can be quickly formed using stamping or milling, which is simple, convenient, and low-cost.

[0016] As an optional technical solution in this application embodiment, the at least one weak segment includes at least one first weak segment, the weak point is disposed on the first weak segment, the thickness of the first weak segment at the weak point is the first thickness, the thickness of the first weak segment at other positions besides the weak point is the third thickness, and the first thickness is greater than or equal to the third thickness.

[0017] In the above technical solution, the first thickness is greater than the third thickness, meaning the thickness of the first weak segment at the weak point is greater than the thickness of the first weak segment at other locations. The greater thickness of the first weak segment at the weak point compared to other locations strengthens the weak point's resistance to external impacts, reducing the risk of premature failure. Alternatively, the first thickness can be equal to the third thickness, meaning the thickness of the first weak segment at the weak point is equal to the thickness of the first weak segment at other locations. This results in a more uniform thickness for the first weak segment, facilitating manufacturing.

[0018] As an optional technical solution in this application embodiment, the at least one weak segment further includes a second weak segment and a third weak segment, the second weak segment and the third weak segment are opposite to each other and spaced apart, the first weak segment connects the second weak segment and the third weak segment, the thickness of the second weak segment and the third weak segment are both a fourth thickness, and the fourth thickness is less than the third thickness.

[0019] In the above technical solution, when a battery cell is depressurized, the weak point can open along the first, second, and third weak sections, resulting in a larger depressurization area and improving the depressurization rate. The first weak section is closer to the center of the first region than the second and third weak sections, and the thickness of the first weak section, except at the weak point, can be greater than that of the second and third weak sections, thereby enhancing the weak point's resistance to external impacts and reducing the risk of premature failure.

[0020] As an optional technical solution in this application embodiment, one end of the first weak segment is connected to the middle of the second weak segment, the other end of the first weak segment is connected to the middle of the third weak segment, and the weak point is located at the midpoint of the first weak segment.

[0021] In the above technical solution, when a battery cell is depressurized, the weak point, after being damaged, can rupture along the first weak segment towards the second and third weak segments respectively. After reaching the intersection of the first and second weak segments, it ruptures from the intersection along the extension direction of the second weak segment towards both ends. After reaching the intersection of the first and third weak segments, it ruptures from the intersection along the extension direction of the third weak segment towards both ends, thereby achieving rapid depressurization.

[0022] As an optional technical solution in this application embodiment, the second weak segment includes a first end and a second end, the third weak segment includes a third end and a fourth end, the first end and the third end are arranged opposite to each other, the second end and the fourth end are arranged opposite to each other, the first weak segment connects the first end and the fourth end or connects the second end and the third end, and the weak point is located at the midpoint of the first weak segment.

[0023] In the above technical solution, when a battery cell is depressurized, the weak point, after being damaged, can rupture along the first weak segment towards the second and third weak segments respectively. After reaching the intersection of the first and second weak segments, it ruptures from the intersection along the extension direction of the second weak segment towards the other end of the second weak segment. After reaching the intersection of the first and third weak segments, it ruptures from the intersection along the extension direction of the third weak segment towards the other end of the third weak segment, thereby achieving rapid depressurization.

[0024] As an optional technical solution in this application embodiment, the at least one weak segment further includes a fourth weak segment and a fifth weak segment. The fourth weak segment and the fifth weak segment are opposite to each other and spaced apart. The second weak segment and the fourth weak segment intersect at a first end. The third weak segment and the fifth weak segment intersect at a second end. The first weak segment connects the first end and the second end. The weak point is located at the midpoint of the first weak segment.

[0025] In the above technical solution, when a battery cell is depressurized, the weak point is damaged and can rupture along the first weak segment towards the first end and the second end respectively. After reaching the first end, it ruptures from the first end along the second and fourth weak segments respectively. After reaching the second end, it ruptures from the second end along the third and fourth weak segments respectively, thereby achieving rapid depressurization.

[0026] As an optional technical solution in this application embodiment, the at least one weak segment further includes a sixth weak segment, and the first weak segment and the sixth weak segment intersect at the weak point.

[0027] In the above technical solution, when the weak point is the intersection of the first weak segment and the sixth weak segment, the stress is more concentrated and it is easier to break. Therefore, the thickness of the weak part at the weak point can be set to be thicker, so that the weak point can resist external impacts more effectively when the battery cell is in normal use, thereby reducing the risk of the weak part being damaged prematurely.

[0028] As an optional technical solution in this application embodiment, the projection of the weak part on the outer surface of the wall is a closed structure, and the closed structure surrounds the center point.

[0029] In the above technical solution, the weak part is a closed structure extending along a closed trajectory. In this way, when the internal pressure of the battery cell reaches the explosion pressure, the internal pressure can push open the weak part from all sides, forming a larger opening, making the pressure relief faster and easier.

[0030] As an optional technical solution in this application embodiment, the center of the projection of the weak part coincides with the center point along the thickness direction of the wall.

[0031] In the above technical solution, when the weak point coincides with the center point, the deformation of the weak point is the greatest and the most likely to break when the battery cell is depressurized. Therefore, the thickness of the weak point can be made thicker so that the weak point can resist external impacts more effectively when the battery cell is in normal use, thereby reducing the risk of the weak point being damaged prematurely.

[0032] As an optional technical solution in this application embodiment, along the thickness direction of the wall portion, the center of the projection of the weak portion is offset from the center point.

[0033] In the above technical solution, by making the center of the projection of the weak part along the thickness direction deviate from the center point, it is beneficial to improve the creep resistance of the weak part.

[0034] As an optional technical solution in this application embodiment, the distance B between the center of the projection of the weak part along the thickness direction and the center point satisfies: 0 < B ≤ 5 mm.

[0035] In the above technical solution, by limiting the distance between the center of the projection of the weak part along the thickness direction and the center point to within 0 to 5 mm (excluding 0), the creep resistance of the weak part is better.

[0036] As an optional technical solution in this application embodiment, 0 < B ≤ 3 mm.

[0037] In the above technical solution, by limiting the distance between the center of the projection of the weak part along the thickness direction and the center point to within 0 to 3 mm (excluding 0), the weak part has good creep resistance. At the same time, the thickness of the weak part is relatively large, which makes the weak part more resistant to external impacts when the battery cell is in normal use, and helps to reduce the risk of the weak part being damaged prematurely.

[0038] As an optional technical solution in this application embodiment, the wall portion includes a body portion, and the weak portion is integrally formed with the body portion.

[0039] In the above technical solution, integrally molding the weak part with the main body can improve the rigidity of the weak part, thereby making the weak part more resistant to the creep and impact of the electrolyte, which is beneficial to improving the life of the weak part and reducing the risk of leakage in the weak part.

[0040] As an optional technical solution in this application embodiment, the hardness of the weak part is greater than the hardness of the body part.

[0041] In the above technical solution, the weak part can be formed by stamping, which causes cold work hardening (changes in grain arrangement, leading to lattice distortion, reducing metal plasticity, and increasing material hardness). The hardness of the weak part will be greater than that of the main body, enhancing its resistance to external impacts and making it less susceptible to damage from external impacts. In addition, the weak part has better fatigue resistance and is less prone to fatigue failure.

[0042] As an optional technical solution in this application embodiment, the wall portion includes a body portion and a pressure relief mechanism. The pressure relief mechanism is separately disposed and connected to the body portion. The weak portion is disposed on the pressure relief mechanism. The outer surface of the body portion is the outer surface of the wall portion.

[0043] In the above technical solution, the pressure relief mechanism is separately set and installed on the main body to facilitate processing and manufacturing.

[0044] As an optional technical solution in this application embodiment, the outer shell includes a housing and an end cap, the housing has an opening, the end cap closes the opening and is fixed to the housing; the wall portion is the end cap or a wall of the housing.

[0045] In the above technical solution, the wall portion can be an end cap, the bottom wall of the casing, or the side wall of the casing. The weak portion is located in the first region of the end cap, bottom wall, or side wall. Under the same detonation pressure, the thickness of the weak portion located in the first region can be greater. In this way, when the battery cell is in normal use, the weak portion has a stronger ability to resist external impacts, which helps to reduce the risk of premature damage to the weak portion.

[0046] Secondly, embodiments of this application also provide a battery, the battery comprising the aforementioned battery cell.

[0047] Thirdly, embodiments of this application also provide an electrical device, the electrical device including the aforementioned battery, the battery being used to provide electrical energy to the electrical device. Attached Figure Description

[0048] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0050] Figure 2 Exploded views of batteries provided for some embodiments of this application;

[0051] Figure 3 This is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0052] Figure 4 A top view schematic diagram of a battery cell provided in some embodiments of this application;

[0053] Figure 5 This is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0054] Figure 6 A top view schematic diagram of a battery cell provided in some embodiments of this application;

[0055] Figure 7 A top view schematic diagram of a battery cell provided for other embodiments of this application;

[0056] Figure 8 for Figure 7 A cross-sectional view of the EE location;

[0057] Figure 9A top view schematic diagram of a battery cell provided for some embodiments of this application;

[0058] Figure 10 The present application also provides top view schematic diagrams of battery cells in some embodiments;

[0059] Figure 11 A top view schematic diagram of a battery cell provided for some other embodiments of this application;

[0060] Figure 12 A top view schematic diagram of a battery cell provided for some other embodiments of this application;

[0061] Figure 13 A top view schematic diagram of a battery cell provided in some further embodiments of this application;

[0062] Figure 14 This is a top view schematic diagram of a battery cell provided in some embodiments of this application;

[0063] Figure 15 A side view schematic diagram of a battery cell provided for further embodiments of this application;

[0064] Figure 16 The present application provides further structural schematic diagrams of battery cells in some embodiments.

[0065] Icons: 10-Box; 11-First part; 12-Second part; 20-Battery cell; 21-Weak section; 211-First weak segment; 2111-Weak point; 212-Second weak segment; 2121-First end; 2122-Second end; 213-Third weak segment; 2131-Third end; 2132-Fourth end; 214-Fourth weak segment; 215-Fifth weak segment; 216-Sixth weak segment; 22-Outer shell; 221-Wall; 2211-First area; 2212-Scratched groove; 2213-Center point; 222-Shell; 2221-Side wall; 2222-Bottom wall; 223-End cap; 23-Electrode terminal; 100-Battery; 200-Controller; 300-Motor; 1000-Vehicle. Detailed Implementation

[0066] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0067] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0068] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0069] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0070] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0071] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0072] In this application, "multiple" means two or more (including two).

[0073] In this application, the battery cell may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application are not limited to these. The battery cell may be cylindrical, flat, cuboid, or other shapes, etc., and the embodiments of this application are not limited to these. Battery cells are generally divided into three types according to their packaging method: cylindrical battery cells, square battery cells, and pouch battery cells, and the embodiments of this application are not limited to these.

[0074] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application may include a battery module or a battery pack. A battery generally includes a housing for encapsulating one or more battery cells. The housing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0075] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrodes. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector. The uncoated positive current collector protrudes from the coated positive current collector and serves as the positive electrode tab. Taking a lithium-ion battery as an example, the positive current collector can be made of aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector. The uncoated negative current collector protrudes from the coated negative current collector and serves as the negative electrode tab. The negative current collector can be made of copper, and the negative active material can be carbon or silicon, etc. To ensure that a large current can pass through without melting, multiple positive tabs and multiple negative tabs are stacked together. The separator can be made of PP (polypropylene) or PE (polyethylene), etc. Furthermore, the electrode assembly can be a wound structure or a stacked structure; the embodiments of this application are not limited to these.

[0076] The development of battery technology must take into account multiple design factors, such as energy density, cycle life, discharge capacity, charge-discharge rate and other performance parameters. In addition, battery reliability also needs to be considered.

[0077] To ensure the reliability of individual battery cells, pressure relief mechanisms can be incorporated into their casings. For example, a weak point can be designed on the end cap. When the internal pressure of the battery cell reaches the detonation pressure, the weak point is breached, releasing the internal pressure and reducing the risk of explosion or fire. However, the weak point often opens prematurely, preventing the proper pressure relief function from being achieved.

[0078] The casing of a battery cell is susceptible to external impacts, which can easily affect weak points, causing these weak points to open prematurely and preventing the normal pressure relief function from being achieved.

[0079] Therefore, this application provides a battery cell including a casing with a wall. The wall includes a weak portion configured to be destroyed when the battery cell releases internal pressure. The outer surface of the wall has a center point. The maximum distance between the projection of the weak portion onto the outer surface of the wall and the center point is 'a', and the minimum radial dimension of the outer surface of the wall is 'A', both satisfying a ≤ 0.4A. Radial refers to the direction passing through the center point.

[0080] By ensuring that a ≤ 0.4A, meaning the maximum distance between the projection of the weak portion onto the outer surface of the wall and the center point of the outer surface of the wall is less than or equal to 0.4 times the minimum radial dimension of the outer surface of the wall, the weak portion is located in a first region of the wall with relatively low stiffness. The first region is a circular area with the center point of the outer surface of the wall as its center and a radius of 0.4 times the minimum radial dimension of the outer surface of the wall. The first region is close to the center of the wall and has relatively low stiffness, making it less resistant to deformation. When the battery cell releases internal pressure, the first region undergoes significant deformation under the action of gas, making the weak portion located there prone to deformation and failure. Therefore, under the same detonation pressure, the thickness of the weak portion located in the first region can be greater. This increases the weak portion's resistance to external impacts during normal use of the battery cell, reducing the risk of premature failure. Furthermore, a larger weak portion is easier to manufacture, requiring less precision from the manufacturing equipment.

[0081] The technical solutions described in the embodiments of this application are applicable to batteries and electrical devices that use batteries.

[0082] Electrical equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical equipment.

[0083] For ease of explanation, the following embodiments will use a vehicle 1000 as an example of electrical equipment.

[0084] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery 100 is disposed inside the vehicle 1000, and the battery 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0085] In some embodiments of this application, the battery 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0086] Please refer to Figure 2 , Figure 2This is an exploded view of a battery 100 provided in some embodiments of this application. The battery 100 includes a housing 10 and a battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 provides a space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, which overlap each other, jointly defining a space for accommodating the battery cell 20. The second portion 12 may be a hollow structure with one open end, and the first portion 11 may be a plate-like structure, covering the open side of the second portion 12 so that the first portion 11 and the second portion 12 jointly define the space; alternatively, the first portion 11 and the second portion 12 may both be hollow structures with one open side, with the open side of the first portion 11 covering the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder, a cuboid, etc.

[0087] In battery 100, there can be multiple battery cells 20, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, battery 100 can also be composed of multiple battery cells 20 first connected in series, parallel, or in a mixed manner to form a battery module, and then multiple battery modules are connected in series, parallel, or in a mixed manner to form a whole, which is also housed within the housing 10. Battery 100 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 20.

[0088] Each battery cell 20 can be a secondary battery cell or a primary battery cell; it can also be a lithium-sulfur battery cell, a sodium-ion battery cell, or a magnesium-ion battery cell, but is not limited to these. The battery cell 20 can be cylindrical, flat, cuboid, or other shapes.

[0089] Please refer to Figure 3 , Figure 4 , Figure 5 and Figure 6 , Figure 3 This is a schematic diagram of the structure of a battery cell 20 provided in some embodiments of this application. Figure 4 This is a top view schematic diagram of a battery cell 20 provided in some embodiments of this application. Figure 5 This is a schematic diagram of the structure of a battery cell 20 provided in some embodiments of this application. Figure 6This is a top view schematic diagram of a battery cell 20 provided in some embodiments of this application. Embodiments of this application provide a battery cell 20, which includes a housing 22. The housing 22 has a wall 221, and the wall 221 includes a weak portion 21 configured to be destroyed when the battery cell 20 releases internal pressure. The outer surface of the wall 221 has a center point 2213. The maximum distance between the projection of the weak portion 21 onto the outer surface of the wall 221 and the center point 2213 is 'a', and the minimum radial dimension of the outer surface of the wall 221 is 'A', both satisfying a ≤ 0.4A. Radial refers to the direction passing through the center point 2213.

[0090] The housing 22 includes an end cap 223 and a housing 222, the housing 222 having a receiving space with an opening at one end for accommodating an electrode assembly. The end cap 223 is connected to the housing 222 and closes the opening.

[0091] End cap 223 refers to a component that covers the opening of housing 222 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 223 can be adapted to the shape of housing 222 to fit it. Optionally, end cap 223 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 223 is less prone to deformation under pressure and impact, enabling battery cell 20 to have higher structural strength and improved reliability. The material of end cap 223 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose special limitations on this. In some embodiments, battery cell 20 further includes an insulating component disposed inside end cap 223. The insulating component can be used to isolate the electrical connection components inside housing 222 from end cap 223 to reduce the risk of short circuit. For example, the insulating component can be plastic, rubber, etc.

[0092] The housing 222 is a component used to cooperate with the end cap 223 to form the internal environment of the battery cell 20. This internal environment can accommodate the electrode assembly 23, electrolyte, and other components. The housing 222 and the end cap 223 can be independent components. An opening can be provided on the housing 222, and the end cap 223 can be used to close the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 223 and the housing 222 can be integrated. Specifically, the end cap 223 and the housing 222 can form a common mating surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 222, the end cap 223 closes the housing 222. The housing 222 can be of various shapes and sizes, such as cuboid, cylindrical, or hexagonal prism. Specifically, the shape of the housing 222 can be determined according to the specific shape and size of the electrode assembly 23. The material of the housing 222 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, or plastic. This embodiment does not impose any special limitations on this.

[0093] Electrode assemblies are components within the battery cell 20 where electrochemical reactions occur. The casing 22 may contain one or more electrode assemblies. Electrode assemblies are primarily formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body of the electrode assembly, while the portions without active material each constitute a tab. The positive and negative tabs may be located together at one end of the main body or separately at both ends of the main body. During the charging and discharging process of the battery 100, the positive and negative active materials react with the electrolyte.

[0094] Electrode terminals 23 can be disposed on the housing 22. These terminals 23 can be electrically connected to the electrode assembly for input or output of electrical energy from the battery cell 20. The electrode terminals 23 can be disposed on the end cap 223 or on the housing 222. Figure 3 In the embodiment shown, electrode terminal 23 is disposed on end cap 223.

[0095] The weak point 21 is a structure used to open when the internal pressure or temperature of the battery cell 20 reaches the detonation pressure, so as to release the internal pressure of the battery cell 20 and reduce the risk of the battery cell 20 exploding or catching fire.

[0096] The outer casing 22 has multiple walls, such as a bottom wall 2222 and side walls 2221. Each wall on the outer casing 22 can serve as a wall portion 221. For example, the bottom wall 2222 can be a wall portion 221, in which case the weak portion 21 is provided on the bottom wall 2222. Similarly, the side wall 2221 can be a wall portion 221, in which case the weak portion 21 is provided on the side wall 2221. In particular, the end cap 223 can be a single wall portion 221, in which case the weak portion 21 is provided on the end cap 223. It should be noted that the outer casing 22 can have multiple wall portions 221, in which case each wall portion 221 is provided with a weak portion 21. For example, both the bottom wall 2222 and the side wall 2221 can be wall portions 221, in which case both the bottom wall 2222 and the side wall 2221 are provided with weak portions 21.

[0097] The outer surface of the wall portion 221 has a center point 2213. Please refer to... Figure 3 and Figure 4 Taking the wall portion 221 as an example of a rectangular structure, the center point 2213 of the outer surface of the wall portion 221 is the intersection of the diagonals of the rectangle. Please refer to... Figure 5 and Figure 6 Taking the wall portion 221 as an example, the center point 2213 of the outer surface of the wall portion 221 is the center of the circle.

[0098] 'a' represents the maximum distance between the projection of the weak part 21 onto the outer surface of the wall portion 221 and the center point 2213, which is also the distance between the point farthest from the center point 2213 in the projection of the weak part 21 onto the outer surface of the wall portion 221 and the center point 2213. For example, if the weak part 21 is circular, and the center of the circle coincides with the center point 2213, then the maximum distance between the projection of the weak part 21 onto the outer surface of the wall portion 221 and the center point 2213 is the radius of the circle corresponding to the weak part 21. Similarly, if the weak part 21 is circular, and any point on the weak part 21 coincides with the center point 2213, then the maximum distance between the projection of the weak part 21 onto the outer surface of the wall portion 221 and the center point 2213 is the diameter of the circle corresponding to the weak part 21.

[0099] A represents the minimum radial dimension of the outer surface of wall portion 221. The "minimum radial dimension of the outer surface of wall portion 221" refers to the dimension of the shortest straight line segment among multiple straight line segments that pass through the center point 2213 and have any two endpoints on the edge of wall portion 221 as endpoints. Please refer to... Figure 3 and Figure 4 ,exist Figure 3 and Figure 4 In the illustrated embodiment, the outer surface of the wall portion 221 is rectangular, and the minimum radial dimension of the outer surface of the wall portion 221 is the width of the rectangle. Please refer to... Figure 5 and Figure 6 ,exist Figure 5 and Figure 6In the illustrated embodiment, the outer surface of the wall portion 221 is circular, and the minimum radial dimension of the outer surface of the wall portion 221 is the diameter of the circle. Alternatively, in some embodiments, the outer surface of the wall portion 221 is a regular hexagon, in which case the minimum radial dimension of the outer surface of the wall portion 221 is the distance between two parallel sides of the regular hexagon.

[0100] The statement "The maximum distance 'a' between the projection of the weak part 21 onto the outer surface of the wall 221 and the center point 2213, and the minimum radial dimension of the outer surface of the wall 221, satisfies: a ≤ 0.4A" can be understood as follows: The weak part 21 is located within the first region 2211 of the wall 221. The edge of the weak part 21 can overlap with the edge of the first region 2211, but cannot extend beyond the first region 2211. The first region 2211 is a circular region with the center point 2213 of the outer surface of the wall 221 as its center and a radius of 0.4 times the minimum radial dimension of the outer surface of the wall 221 as its radius. The first region 2211 is the region on the wall 221 near its center. Compared to the region near the edge of the wall 221, the first region 2211 has lower stiffness. When the internal pressure of the battery cell 20 reaches the detonation pressure, the deformation of the first region 2211 is larger.

[0101] Please refer to Figure 3 , Figure 4 , Figure 5 and Figure 6 ,exist Figure 3 , Figure 4 , Figure 5 and Figure 6 The boundary of the first region 2211 is shown by a dashed line. The first region 2211 is the area enclosed by the dashed line. It should be noted that the dashed line is only for showing the boundary of the first region 2211 and does not indicate that there are other entities or structures obscured at the location of the dashed line.

[0102] By ensuring that a ≤ 0.4A, meaning the maximum distance between the projection of the weak portion 21 onto the outer surface of the wall portion 221 and the center point 2213 of the outer surface of the wall portion 221 is less than or equal to 0.4 times the minimum radial dimension of the outer surface of the wall portion 221, the weak portion 21 is disposed in a first region 2211 of the wall portion 221 with relatively low stiffness. The first region 2211 is a circular region with the center point 2213 of the outer surface of the wall portion 221 as its center and a radius of 0.4 times the minimum radial dimension of the outer surface of the wall portion 221 as its radius. The first region 2211 is close to the center of the wall portion 221 and is a region with relatively low stiffness on the wall portion 221, thus having weak resistance to deformation. When the battery cell 20 releases its internal pressure, the first region 2211 undergoes significant deformation under the action of gas, and the weak portion 21 disposed in the first region 2211 is easily deformed and damaged. Therefore, under the same detonation pressure, the thickness of the weak portion 21 disposed in the first region 2211 can be greater. In this way, when the battery cell 20 is in normal use, the weak part 21 is more resistant to external impacts, which helps to reduce the risk of premature failure of the weak part 21. Furthermore, the greater the thickness of the weak part 21, the easier it is to manufacture, and the lower the precision requirements of the manufacturing equipment.

[0103] Please refer to Figure 7 and Figure 8 , Figure 7 This is a top view of a battery cell 20 provided in some other embodiments of this application. Figure 8 for Figure 7 A cross-sectional view at the EE position. In some embodiments, the wall portion 221 is provided with a groove 2212, and a weak portion 21 is formed at the bottom of the groove 2212.

[0104] The groove 2212 can be formed in various ways, such as stamping or milling. The groove 2212 can be located on the surface of the wall 221 facing the interior of the outer shell 22, or on the surface of the wall 221 away from the interior of the outer shell 22. Taking a rectangular flat plate structure as an example, the wall 221 has opposing inner and outer surfaces in the thickness direction. The inner surface of the wall 221 faces the interior of the outer shell 22, and the outer surface of the wall 221 is located away from the interior of the outer shell 22. The groove 2212 can be located on either the inner or outer surface of the wall 221.

[0105] The groove 2212 can be a recessed groove extending from the outer surface of the wall portion 221 along the thickness direction of the wall portion 221, and the weak portion 21 is the part of the wall portion 221 located between the inner surface and the bottom surface of the groove 2212. Alternatively, the groove 2212 can be a recessed groove extending from the inner surface of the wall portion 221 along the thickness direction of the wall portion 221, and the weak portion 21 is the part of the wall portion 221 located between the outer surface and the bottom surface of the groove 2212.

[0106] The groove 2212 is a recessed groove that is recessed from the outer surface of the wall portion 221 along the thickness direction of the wall portion 221. Please refer to [reference needed]. Figure 3 and Figure 4 The groove 2212 can be a straight groove extending along a straight trajectory. Please refer to... Figure 5 and Figure 6 The groove 2212 can also be an annular groove extending along a closed trajectory.

[0107] The weak part 21 is formed by creating a groove 2212 on the wall 221, which is simple, convenient and low cost.

[0108] Please refer to Figure 7 and Figure 8 In some embodiments, the projection of the weak portion 21 onto the outer surface of the wall portion 221 passes through the center point 2213.

[0109] The statement "the projection of the weak part 21 onto the outer surface of the wall part 221 passes through the center point 2213" can be understood as: the projection of the weak part 21 onto the outer surface of the wall part 221 covers the center point 2213. The center point 2213 can be located at the edge of the projection of the weak part 21 onto the outer surface of the wall part 221. For example, if the weak part 21 is a straight structure, the center point 2213 is located at one end of the projection of the weak part 21 onto the outer surface of the wall part 221. Alternatively, the center point 2213 can be located at the middle of the projection of the weak part 21 onto the outer surface of the wall part 221. For example, if the weak part 21 is a straight structure, the center point 2213 is located at the midpoint of the projection of the weak part 21 onto the outer surface of the wall part 221.

[0110] When the internal pressure of the battery cell 20 is released, the center point 2213 is the location of the greatest deformation on the wall 221, and it is most vulnerable to damage. By making the projection of the weak part 21 on the outer surface of the wall 221 pass through the center point 2213, the thickness of the weak part 21 at the center point 2213 can be increased. This makes the weak part 21 more resistant to external impacts during normal use of the battery cell 20, thereby reducing the risk of premature damage to the weak part 21.

[0111] Please refer to Figure 7 and Figure 8 In some embodiments, the weak portion 21 has a weak point 2111 corresponding to the center point 2213, and the thickness of the weak portion 21 at the weak point 2111 is a first thickness. The maximum thickness of the weak portion 21 at other locations besides the weak point 2111 is a second thickness. The first thickness is greater than or equal to the second thickness.

[0112] The first thickness is the thickness of the weak part 21 at the weak point 2111, or the thickness of the weak part 21 at the center point 2213. Please refer to... Figure 8 , Figure 8 The first thickness is indicated by H1.

[0113] The second thickness is the maximum thickness at all locations on the weak part 21 except for the weak point 2111. Please refer to... Figure 8 ,like Figure 8 In this context, H3 represents the maximum thickness at locations other than the weak point 2111 on the weak part 21. In this case, H3 represents the second thickness. Therefore, H1 ≥ H3.

[0114] exist Figure 8 In the illustrated embodiment, the first thickness is greater than the second thickness, H1 > H3. In other embodiments, the first thickness may be equal to the second thickness, H1 = H3.

[0115] The first thickness is greater than the second thickness, meaning the thickness of the weak portion 21 at the weak point 2111 is greater than the maximum thickness of the weak portion 21 at other locations. This means the weak point 2111 is thicker than other locations, making it more resistant to external impacts and reducing the risk of premature failure. The first thickness is equal to the second thickness, meaning the thickness of the weak portion 21 at the weak point 2111 is equal to the maximum thickness of the weak portion 21 at other locations. This results in a more uniform thickness for the weak portion 21, facilitating manufacturing.

[0116] Please refer to Figure 7 and Figure 8 In some embodiments, the groove 2212 includes at least one groove segment, and the weak portion 21 includes at least one weak segment, with at least one groove segment and at least one weak segment being provided in a one-to-one correspondence.

[0117] The groove 2212 may include two groove segments, which are arranged intersectingly. Correspondingly, the weak portion 21 is provided with two weak segments, which are arranged intersectingly.

[0118] Please refer to Figure 7 and Figure 8 The groove 2212 includes three groove segments. Correspondingly, the weak part 21 is provided with three weak segments. The arrangement of the three weak segments is the same as the arrangement of the three groove segments.

[0119] Of course, the groove 2212 may include more than three groove segments, and correspondingly, the weak part 21 is also provided with more than three weak segments. The arrangement of the more than three weak segments is the same as the arrangement of the more than three groove segments.

[0120] Each groove segment on the wall 221 corresponds to a weak segment. During manufacturing, it can be quickly formed by stamping or milling, which is simple, convenient, and low-cost.

[0121] Please refer to Figure 7 and Figure 8 In some embodiments, at least one weak segment includes at least one first weak segment 211, and a weak point 2111 is disposed on the first weak segment 211. The thickness of the first weak segment 211 at the weak point 2111 is a first thickness. The thickness of the first weak segment 211 at other locations besides the weak point 2111 is a third thickness. The first thickness is greater than or equal to the third thickness.

[0122] At least one weak segment may include one first weak segment 211, two first weak segments 211, three first weak segments 211, or more than three first weak segments 211. When at least one weak segment includes multiple first weak segments 211, the multiple weak segments intersect at a weak point 2111.

[0123] Please refer to Figure 7 and Figure 8 ,exist Figure 7 and Figure 8 In the illustrated embodiment, at least one weak segment includes a first weak segment 211, and the thickness of the first weak segment 211 at the weak point 2111 is a first thickness, such as... Figure 8 As shown in H1.

[0124] The thickness of the first weak segment 211 at locations other than the weak point 2111 is the third thickness. The thickness of the first weak segment 211 at locations other than the weak point 2111 can be non-uniform; for example, the thickness of the first weak segment 211 at locations other than the weak point 2111 can gradually increase or decrease along the extension direction of the first weak segment 211. In this case, the third thickness is the maximum thickness of the first weak segment 211 at locations other than the weak point 2111. Alternatively, the thickness of the first weak segment 211 at locations other than the weak point 2111 can be uniform, meaning the thickness of any other location of the first weak segment 211 is the same. Therefore, the thickness of any other location of the first weak segment 211 can be taken as the third thickness.

[0125] Please refer to Figure 8 The third thickness is Figure 8 As shown in H3. In Figure 8 In the embodiment shown, the thickness of the first weak segment 211 at the weak point 2111 is greater than the thickness of the first weak segment 211 at other locations besides the weak point 2111, that is, H1 > H3.

[0126] In some other embodiments, the thickness of the first weak segment 211 at the weak point 2111 can be equal to the thickness of the first weak segment 211 at other locations besides the weak point 2111, that is, H1 = H3. In this case, the thickness of the first weak segment 211 at other locations besides the weak point 2111 represents both the third thickness and the second thickness.

[0127] The first thickness is greater than the third thickness, meaning the thickness of the first weak segment 211 at the weak point 2111 is greater than the thickness of the first weak segment 211 at other locations. Because the first weak segment 211 is thicker at the weak point 2111 than at other locations, the weak point 2111 has stronger resistance to external impacts, reducing the risk of premature failure of the weak part 21. The first thickness is equal to the third thickness, meaning the thickness of the first weak segment at the weak point 2111 is equal to the thickness of the first weak segment 211 at other locations. This makes the thickness of the first weak segment 211 relatively more uniform, thus facilitating processing and manufacturing.

[0128] Please refer to Figure 7 and Figure 8 In some embodiments, at least one weak segment further includes a second weak segment 212 and a third weak segment 213, which are opposite to and spaced apart. A first weak segment 211 connects the second weak segment 212 and the third weak segment 213. The thickness of both the second weak segment 212 and the third weak segment 213 is a fourth thickness, and the fourth thickness is less than the third thickness.

[0129] The first weak segment 211, the second weak segment 212, and the third weak segment 213 can all be straight segments or non-straight segments, such as arc segments. In embodiments where the first weak segment 211, the second weak segment 212, and the third weak segment 213 are all straight segments, it is understood that the first weak segment 211, the second weak segment 212, and the third weak segment 213 all extend along a straight line. The second weak segment 212 and the third weak segment 213 can be arranged parallel to each other or at an angle. The second weak segment 212 and the third weak segment 213 can be perpendicular to the first weak segment 211 or not perpendicular to the first weak segment 211.

[0130] The connection point between the second weak segment 212 and the first weak segment 211 can be located at one end of the second weak segment 212 or at a position offset from one end of the second weak segment 212. For example, the connection point between the second weak segment 212 and the first weak segment 211 can be located at the midpoint of the second weak segment 212 in the extension direction. The connection point between the third weak segment 213 and the first weak segment 211 can be located at one end of the third weak segment 213 or at a position offset from one end of the third weak segment 213. For example, the connection point between the third weak segment 213 and the first weak segment 211 can be located at the midpoint of the third weak segment 213 in the extension direction.

[0131] The thickness of the second weak segment 212 is the same as the thickness of the third weak segment 213. The thickness of the second weak segment 212 can be non-uniform; for example, the thickness of the second weak segment 212 can gradually increase along its extension direction. In this case, the fourth thickness is the maximum thickness of the second weak segment 212. The thickness of the second weak segment 212 can also be uniform, meaning that the thickness of the second weak segment 212 is the same at any position, and the thickness of the second weak segment 212 at any position can be taken as the fourth thickness.

[0132] Please refer to Figure 8 The fourth thickness is as follows Figure 8 As shown in H4. The fourth thickness is less than the third thickness, that is: H4 < H3. At this time, the maximum thickness of the second weak segment 212 is less than the minimum thickness of the first weak segment 211 at any other position except the weak segment.

[0133] When the battery cell 20 is depressurized, the weak portion 21 can open along the first weak section 211, the second weak section 212, and the third weak section 213, providing a larger depressurization area and thus improving the depressurization rate. The first weak section 211 is closer to the center of the first region 2211 than the second weak section 212 and the third weak section 213. The thickness of the first weak section 211, except for the weak point 2111, can also be greater than the thickness of the second weak section 212 and the third weak section 213, thereby enhancing the resistance of the weak portion 21 to external impacts and reducing the risk of premature failure of the weak portion 21.

[0134] Please refer to Figure 7 and Figure 8 In some embodiments, one end of the first weak segment 211 is connected to the middle of the second weak segment 212, and the other end of the first weak segment 211 is connected to the middle of the third weak segment 213. The weak point 2111 is located at the midpoint of the first weak segment 211.

[0135] The first weak segment 211 has two opposite ends, one end of which is connected to the second weak segment 212 and the other end of which is connected to the third weak segment 213.

[0136] "One end of the first weak segment 211 is connected to the middle of the second weak segment 212" means that one end of the first weak segment 211 is connected to the midpoint of the second weak segment 212 or to an area within 3mm of the midpoint.

[0137] "The other end of the first weak segment 211 is connected to the middle of the third weak segment 213" means that the other end of the first weak segment 211 is connected to the midpoint of the third weak segment 213 or to an area within 3mm away from the midpoint.

[0138] Please refer to Figure 7 ,exist Figure 7 In the illustrated embodiment, the first weak segment 211, the second weak segment 212, and the third weak segment 213 form an H-shaped weak portion 21. The midpoint of the first weak segment 211 is the weak point 2111.

[0139] When the battery cell 20 is depressurized, the weak point 2111 is damaged and can rupture along the first weak segment 211 towards the second weak segment 212 and the third weak segment 213 respectively. After reaching the intersection of the first weak segment 211 and the second weak segment 212, it ruptures from the intersection along the extension direction of the second weak segment 212 towards both ends. After reaching the intersection of the first weak segment 211 and the third weak segment 213, it ruptures from the intersection along the extension direction of the third weak segment 213 towards both ends, thereby achieving rapid depressurization.

[0140] Please refer to Figure 9 , Figure 9 This is a top view schematic diagram of a battery cell 20 provided in some embodiments of this application. In some embodiments, the second weak segment 212 includes a first end 2121 and a second end 2122, and the third weak segment 213 includes a third end 2131 and a fourth end 2132. The first end 2121 and the third end 2131 are disposed opposite to each other, and the second end 2122 and the fourth end 2132 are disposed opposite to each other. The first weak segment 211 connects the first end 2121 and the fourth end 2132 or connects the second end 2122 and the third end 2131. The weak point 2111 is located at the midpoint of the first weak segment 211.

[0141] The first end 2121 and the second end 2122 are the two ends of the second weak segment 212 along its extension direction. The third end 2131 and the fourth end 2132 are the two ends of the third weak segment 213 along its extension direction. The first end 2121 and the third end 2131 are opposite each other, and the second end 2122 and the fourth end 2132 are opposite each other.

[0142] The first weak segment 211 is inclined, and one end of the first weak segment 211 can be connected to the first end 2121. At this time, the other end of the first weak segment 211 is connected to the fourth end 2132. One end of the first weak segment 211 can be connected to the second end 2122. At this time, the other end of the first weak segment 211 is connected to the third end 2131. The first weak segment 211, the second weak segment 212, and the third weak segment 213 form a Z-shaped groove 2212. The midpoint of the first weak segment 211 is the weak point 2111.

[0143] When the battery cell 20 is depressurized, the weak point 2111 is damaged and can rupture along the first weak segment 211 towards the second weak segment 212 and the third weak segment 213 respectively. After reaching the intersection of the first weak segment 211 and the second weak segment 212, it ruptures from the intersection along the extension direction of the second weak segment 212 towards the other end of the second weak segment 212. After reaching the intersection of the first weak segment 211 and the third weak segment 213, it ruptures from the intersection along the extension direction of the third weak segment 213 towards the other end of the third weak segment 213, thereby achieving rapid depressurization.

[0144] Please refer to Figure 10 , Figure 10 The diagram below shows a top view of a battery cell 20 provided in some embodiments of this application. In some embodiments, at least one weak segment further includes a fourth weak segment 214 and a fifth weak segment 215, which are opposite to and spaced apart. A second weak segment 212 and a fourth weak segment 214 intersect at a first end 2121, and a third weak segment 213 and a fifth weak segment 215 intersect at a second end 2122. A first weak segment 211 connects the first end 2121 and the second end 2122, and a weak point 2111 is located at the midpoint of the first weak segment 211.

[0145] The first weak segment 211, the second weak segment 212, the third weak segment 213, the fourth weak segment 214, and the fifth weak segment 215 can all be straight segments or non-straight segments, such as an arc-shaped groove. The first weak segment 211, the second weak segment 212, and the fourth weak segment 214 intersect at the first end 2121. The first weak segment 211, the third weak segment 213, and the fifth weak segment 215 intersect at the second end 2122. The first end 2121 and the second end 2122 are the two ends of the first weak segment 211 along its extension direction, respectively.

[0146] When the battery cell 20 is depressurized, the weak point 2111 is damaged and can rupture along the first weak segment 211 towards the first end 2121 and the second end 2122 respectively. After reaching the first end 2121, it ruptures from the first end 2121 along the second weak segment 212 and the fourth weak segment 214 respectively. After reaching the second end 2122, it ruptures from the second end 2122 along the third weak segment 213 and the fourth weak segment 214 respectively, so as to achieve rapid depressurization.

[0147] Please refer to Figure 11 , Figure 11 This is a top view schematic diagram of a battery cell 20 provided in some other embodiments of this application. In some other embodiments, at least one weak segment further includes a sixth weak segment 216, and the first weak segment 211 and the sixth weak segment 216 intersect at a weak point 2111.

[0148] The sixth weak segment 216 can be a straight segment or a non-straight segment, such as an arc segment. In embodiments where the first weak segment 211, the second weak segment 212, the third weak segment 213, and the sixth weak segment 216 are all straight segments, it is understood that the first weak segment 211, the second weak segment 212, the third weak segment 213, and the sixth weak segment 216 all extend along a straight line. The second weak segment 212 and the sixth weak segment 216 can be arranged parallel to each other or at an angle. The third weak segment 213 and the sixth weak segment 216 can be arranged parallel to each other or at an angle. The first weak segment 211 can be perpendicular to the sixth weak segment 216 or not perpendicular to it.

[0149] The connection point between the first weak segment 211 and the sixth weak segment 216 can be located at one end of the sixth weak segment 216 or at a position away from one end of the sixth weak segment 216. For example, the connection point between the first weak segment 211 and the sixth weak segment 216 can be located at the midpoint of the sixth weak segment 216 in the extension direction.

[0150] When the weak point 2111 is the intersection of the first weak segment 211 and the sixth weak segment 216, the stress is more concentrated and it is easier to break. Therefore, the thickness of the weak part 21 at the weak point 2111 can be made thicker so that the weak point 2111 has a stronger ability to resist external impact when the battery cell 20 is in normal use, thereby reducing the risk of the weak part 21 being damaged prematurely.

[0151] Please refer to Figure 12 , Figure 12 This is a top view of a battery cell 20 provided in some other embodiments of this application. In some other embodiments, the projection of the weak portion 21 onto the outer surface of the wall portion 221 is a closed structure, with the closed structure surrounding the center point 2213.

[0152] The projection of the weak part 21 onto the outer surface of the wall part 221 can be a circle, an ellipse, a polygon, etc.

[0153] Please refer to Figure 12 ,exist Figure 12 In the embodiment shown, the projection of the weak part 21 onto the outer surface of the wall 221 is racetrack-shaped. The racetrack shape defines a large area, which allows the weak part 21 to open a large opening in the wall 221 during pressure relief, so as to facilitate rapid pressure relief.

[0154] The weak part 21 is a closed structure extending along a closed trajectory. In this way, when the internal pressure of the battery cell 20 reaches the explosion pressure, the internal pressure can push the weak part 21 open from all sides, forming a larger opening, making the pressure relief faster and easier.

[0155] Please refer to Figure 11 and Figure 12 In some embodiments, the center of the projection of the weak portion 21 coincides with the center point 2213 along the thickness direction of the wall portion 221.

[0156] Along the thickness direction of the wall portion 221, the center of the projection of the weak portion 21 can be located either inside or outside the projection of the weak portion 21. For example, if the projection of the weak portion 21 is a straight line segment along the thickness direction of the wall portion 221, then the midpoint of the straight line segment is the center of the projection of the weak portion 21, and in this case, the center of the projection of the weak portion 21 is located inside the projection of the weak portion 21. As another example, if the projection of the weak portion 21 is annular along the thickness direction of the wall portion 221, then the center of the annular shape is the center of the projection of the weak portion 21, and in this case, the center of the projection of the weak portion 21 is located outside the projection of the weak portion 21.

[0157] Along the thickness direction of the wall portion 221, the center of the weak portion 21 can coincide with the center point 2213, or it can be spaced apart from the center point 2213. Both arrangements can make the center of the projection of the weak portion 21 along the thickness direction coincide with the center of the projection of the center point 2213 along the thickness direction.

[0158] When the weak point 2111 coincides with the center point 2213, its deformation is the greatest and it is most likely to break when the battery cell 20 is depressurized. Therefore, the thickness of the weak part 21 at the weak point 2111 can be made thicker so that the weak point 2111 has a stronger ability to resist external impact when the battery cell 20 is in normal use, thereby reducing the risk of the weak part 21 being damaged prematurely.

[0159] Please refer to Figure 13 and Figure 14 , Figure 13 This is a top view schematic diagram of a battery cell 20 provided in some embodiments of this application. Figure 14This is a top view of a battery cell 20 provided in some embodiments of this application. In some embodiments, the center of the projection of the weak portion 21 is off-center from the center point 2213 along the thickness direction of the wall portion 221.

[0160] The statement "the center of the projection of the weak part 21 is off from the center point 2213 along the thickness direction of the wall 221" can also be understood as: the center of the projection of the weak part 21 does not overlap with the center point 2213 along the thickness direction of the wall 221. Or, in other words, the center of the projection of the weak part 21 is spaced apart from the center point 2213 along a direction perpendicular to the thickness direction of the wall 221.

[0161] By offsetting the center of the projection of the weak part 21 along the thickness direction from the center point 2213, it is beneficial to improve the creep resistance of the weak part 21.

[0162] Please refer to Table 1, which shows the experimental data on the creep resistance of the weak part 21 at different distances from the center point 2213 of the projection along the thickness direction. In Table 1, B represents the distance of the center of the projection of the weak part 21 along the thickness direction from the center point 2213.

[0163] All experiments used 87203 square-shell battery cells with a capacity of 298Ah. The dimensions of the battery cell 20 are 87mm×203mm×112mm, and it is a Ni50 system.

[0164] The specific test method is as follows: a blunt barb with a diameter of 20mm is pressed on the center of the projection of the weak part 21 along the thickness direction. After standing for 7 days, the sinking distance of the weak part 21 is observed. The greater the sinking distance, the worse the creep resistance.

[0165] Table 1

[0166]

[0167] Please refer to Table 1. It can be seen from the table that when the center of the projection of the weak part 21 along the thickness direction deviates from the center point 2213, the creep resistance of the weak part 21 is better than when the center of the projection of the weak part 21 along the thickness direction coincides with the center point 2213.

[0168] Please refer to Figure 13 and Figure 14 In some embodiments, the distance B between the center of the projection of the weak portion 21 along the thickness direction and the center point 2213 satisfies: 0 < B ≤ 5 mm.

[0169] The distance between the center of the projection of the weak part 21 along the thickness direction and the center point 2213 can be: B = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.5, 1.7, 1.9, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.5, 4, 4.5, 5, etc.

[0170] As shown in Table 1, when the center of the projection of the weak part 21 along the thickness direction coincides with the center point 2213, the sinking distance is 1.76 mm. When the center of the projection of the weak part 21 along the thickness direction deviates from the center point 2213 by a distance of 0 to 5 mm (excluding 0), the sinking distance does not exceed 1.7 mm.

[0171] Therefore, by limiting the distance between the center of the projection of the weak part 21 along the thickness direction and the center point 2213 to within 0 to 5 mm (excluding 0), the creep resistance of the weak part 21 is better.

[0172] In some embodiments, 0 < B ≤ 3 mm.

[0173] The distance between the center of the projection of the weak part 21 along the thickness direction and the center point 2213 can be: B = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, etc.

[0174] As shown in Table 1, when 3mm < B ≤ 5mm, the sinking distance is greater than 1.6. However, when 0 < B ≤ 3mm, the sinking distance does not exceed 1.6. Therefore, when 0 < B ≤ 3mm, the creep resistance of the weak part 21 is better.

[0175] By limiting the distance between the center of the projection of the weak part 21 along the thickness direction and the center point 2213 to within 0 to 3 mm (excluding 0), the weak part 21 has good creep resistance. At the same time, the thickness of the weak part 21 is relatively large, which makes the weak part 21 more resistant to external impacts when the battery cell 20 is in normal use, thus reducing the risk of the weak part 21 being damaged prematurely.

[0176] In some embodiments, the wall portion 221 includes a body portion, and the weak portion 21 is integrally formed with the body portion.

[0177] One-piece molding means that the weak part 21 and the main body are provided as a single structure. For example, the weak part 21 can be formed on the wall part 221 by means of stamping or cold heading.

[0178] Integrating the weak part 21 with the main body can improve the rigidity of the weak part 21, thereby making the weak part 21 more resistant to the creep and impact of the electrolyte, which is beneficial to improving the life of the weak part 21 and reducing the risk of leakage.

[0179] In some embodiments, the hardness of the weak portion 21 is greater than the hardness of the body portion.

[0180] The weak part 21 can be formed by stamping, which causes cold work hardening (changes in grain arrangement, leading to lattice distortion, reduced metal plasticity, and increased material hardness). The hardness of the weak part 21 will be greater than that of the main body, enhancing its resistance to external impacts and making it less susceptible to damage. In addition, the weak part 21 has better fatigue resistance and is less prone to fatigue failure.

[0181] In other embodiments, the wall portion 221 includes a body portion and a pressure relief mechanism, which are separately disposed and connected to the body portion. A weak portion 21 is disposed in the pressure relief mechanism, and the outer surface of the body portion is the outer surface of the wall portion 221.

[0182] "The pressure relief mechanism and the main body are separately provided and connected" means that the pressure relief mechanism and the main body are provided separately during manufacturing and then connected together. For example, the pressure relief mechanism may be welded to the main body. In this case, the pressure relief mechanism may protrude from the outer surface of the main body, and the outer surface of the main body is used as the outer surface of the wall portion 221.

[0183] The pressure relief mechanism is separately set and installed on the main body to facilitate manufacturing.

[0184] Please refer to Figure 13 , Figure 15 and Figure 16 , Figure 15 This is a side view of a battery cell 20 provided in some further embodiments of this application. Figure 16 The following are schematic diagrams of the structure of the battery cell 20 provided in some embodiments of this application. In some embodiments, the housing 22 includes a shell 222 and an end cap 223. The shell 222 has an opening, and the end cap 223 closes the opening and is fixed to the shell 222. The wall portion 221 is a wall of the end cap 223 or the shell 222.

[0185] Please refer to Figure 13 ,exist Figure 13 In the embodiment shown, the end cap 223 is a wall portion 221.

[0186] Please refer to Figure 15 ,exist Figure 15In the illustrated embodiment, the housing 222 includes an integrally formed sidewall 2221 and a bottom wall 2222. The sidewall 2221 surrounds the bottom wall 2222, and along the thickness direction of the bottom wall 2222, one end of the sidewall 2221 is connected to the bottom wall 2222, and the other end forms an opening. An end cap 223 closes the opening. The sidewall 2221 is a wall portion 221.

[0187] When providing the housing 222, the sidewall 2221 and the bottom wall 2222 are integral structures. The sidewall 2221 and the bottom wall 2222 can be integrally formed by stamping or by casting. One end of the sidewall 2221 is connected to the bottom wall 2222, and the other end of the sidewall 2221 is connected to the end cap 223. Along the thickness direction of the end cap 223, the bottom wall 2222 and the end cap 223 are arranged opposite to each other.

[0188] Please refer to Figure 16 ,exist Figure 16 In the illustrated embodiment, the outer casing 22 includes a housing 222 and an end cap 223. The housing 222 includes an integrally formed sidewall 2221 and a bottom wall 2222. The sidewall 2221 surrounds the bottom wall 2222, and along the thickness direction of the bottom wall 2222, one end of the sidewall 2221 is connected to the bottom wall 2222, and the other end forms an opening. The end cap 223 closes the opening. The bottom wall 2222 is a wall portion 221.

[0189] The bottom wall 2222 is usually thick, but it is also more susceptible to external impacts. Therefore, by setting the weak part 21 in the first region 2211 of the bottom wall 2222, the thickness of the weak part 21 is increased, so that the weak part 21 has a stronger ability to resist external impacts when the battery cell 20 is in normal use, which helps to reduce the risk of the weak part 21 opening prematurely.

[0190] The wall portion 221 can be an end cap 223, the bottom wall 2222 of the housing 222, or the side wall 2221 of the housing 222. The weak portion 21 is located in a first region 2211 of the end cap 223, the bottom wall 2222, or the side wall 2221. Under the same detonation pressure, the thickness of the weak portion 21 located in the first region 2211 can be greater. In this way, when the battery cell 20 is in normal use, the weak portion 21 has a stronger ability to resist external impacts, which helps to reduce the risk of the weak portion 21 being damaged prematurely.

[0191] This application embodiment also provides a battery 100, which includes the aforementioned battery cell 20.

[0192] This application embodiment also provides an electrical device, which includes the battery 100 described above, and the battery 100 is used to provide electrical energy to the electrical device.

[0193] According to some embodiments of this application, please refer to Figures 3 to 16 .

[0194] This application provides a battery cell 20, which includes a housing 22. The housing 22 has a wall 221, and the wall 221 includes a weak portion 21. The weak portion 21 is configured to be destroyed when the battery cell 20 releases internal pressure. The outer surface of the wall 221 has a center point 2213. The maximum distance between the projection of the weak portion 21 onto the outer surface of the wall 221 and the center point 2213 is 'a', and the minimum radial dimension of the outer surface of the wall 221 is 'A'. Both satisfy: a ≤ 0.4A, where radial refers to the direction passing through the center point 2213. By ensuring that a ≤ 0.4A, i.e., the maximum distance between the projection of the weak portion 21 onto the outer surface of the wall 221 and the center point 2213 of the outer surface of the wall 221 is less than or equal to 0.4 times the minimum radial dimension of the outer surface of the wall 221, the weak portion 21 is disposed in a first region 2211 of the wall 221 with relatively low stiffness. The first region 2211 is a circular area with the center point 2213 of the outer surface of the wall 221 as the center and a radius of 0.4 times the minimum radial dimension of the outer surface of the wall 221 as the radius. The first region 2211 is close to the center of the wall 221 and has relatively low stiffness, making it less resistant to deformation. When the battery cell 20 releases internal pressure, the first region 2211 undergoes significant deformation under the action of gas, making the weak portion 21 located in the first region 2211 prone to deformation and failure. Therefore, under the same detonation pressure, the thickness of the weak portion 21 located in the first region 2211 can be greater. This increases the resistance of the weak portion 21 to external impacts during normal use of the battery cell 20, reducing the risk of premature failure. Furthermore, a larger thickness of the weak portion 21 makes it easier to manufacture and reduces the precision requirements of the manufacturing equipment.

[0195] The wall portion 221 is provided with a groove 2212, and the weak portion 21 is formed at the bottom of the groove 2212. The weak portion 21 is formed by opening a groove 2212 on the wall portion 221, which is simple, convenient and low cost.

[0196] The projection of the weak portion 21 onto the outer surface of the wall portion 221 passes through the center point 2213. When the battery cell 20 releases internal pressure, the center point 2213 is the location of the greatest deformation on the wall portion 221, and it is most vulnerable to damage. By making the projection of the weak portion 21 onto the outer surface of the wall portion 221 pass through the center point 2213, the thickness of the weak portion 21 at the center point 2213 can be increased. This makes the weak portion 21 more resistant to external impacts during normal use of the battery cell 20, thus reducing the risk of premature damage to the weak portion 21.

[0197] The weak portion 21 has a weak point 2111 corresponding to the center point 2213. The thickness of the weak portion 21 at the weak point 2111 is a first thickness, and the maximum thickness at other locations on the weak portion 21 excluding the weak point 2111 is a second thickness. The first thickness is greater than or equal to the second thickness. The first thickness being greater than the second thickness means that the thickness of the weak portion 21 at the weak point 2111 is greater than the maximum thickness at other locations on the weak portion 21 excluding the weak point 2111. Therefore, the weak point 2111 is thicker than other locations, making it more resistant to external impacts and reducing the risk of premature failure of the weak portion 21. The first thickness being equal to the second thickness means that the thickness of the weak portion 21 at the weak point 2111 is equal to the maximum thickness at other locations on the weak portion 21 excluding the weak point 2111. This results in a more uniform thickness for the weak portion 21, facilitating manufacturing.

[0198] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized by, include: The casing has a wall portion, the wall portion including a weak portion, the weak portion being configured to be destroyed when the internal pressure of the battery cell is released, and the outer surface of the wall portion having a center point; The maximum distance between the projection of the weak part onto the outer surface of the wall and the center point is a, and the minimum radial dimension of the outer surface of the wall is A. Both satisfy: a≤0.4A, where radial refers to the direction passing through the center point.

2. The battery cell according to claim 1, characterized in that, The wall portion is provided with a groove, and the weak portion is formed at the bottom of the groove.

3. The battery cell of claim 2, wherein, The projection of the weak portion onto the outer surface of the wall passes through the center point.

4. The battery cell of claim 3, wherein, The weak part has a weak point corresponding to the center point. The thickness of the weak part at the weak point is a first thickness, and the maximum thickness of the weak part at other positions besides the weak point is a second thickness. The first thickness is greater than or equal to the second thickness.

5. The battery cell of claim 4, wherein, The groove includes at least one groove segment, and the weak part includes at least one weak segment. The at least one groove segment and the at least one weak segment are arranged in a one-to-one correspondence.

6. The battery cell of claim 5, wherein, The at least one weak segment includes at least one first weak segment, the weak point is disposed at the first weak segment, the thickness of the first weak segment at the weak point is the first thickness, the thickness of the first weak segment at other locations besides the weak point is the third thickness, and the first thickness is greater than or equal to the third thickness.

7. The battery cell of claim 6, wherein, The at least one weak segment further includes a second weak segment and a third weak segment, the second weak segment and the third weak segment being opposite to each other and spaced apart, the first weak segment connecting the second weak segment and the third weak segment, the thickness of the second weak segment and the third weak segment being a fourth thickness, and the fourth thickness being less than the third thickness.

8. The battery cell of claim 7, wherein, One end of the first weak segment is connected to the middle of the second weak segment, and the other end of the first weak segment is connected to the middle of the third weak segment. The weak point is located at the midpoint of the first weak segment.

9. The battery cell of claim 7, wherein, The second weak segment includes a first end and a second end, and the third weak segment includes a third end and a fourth end. The first end and the third end are arranged opposite to each other, and the second end and the fourth end are arranged opposite to each other. The first weak segment connects the first end and the fourth end or connects the second end and the third end. The weak point is located at the midpoint of the first weak segment.

10. The battery cell according to claim 7, characterized in that, The at least one weak segment further includes a fourth weak segment and a fifth weak segment, the fourth weak segment and the fifth weak segment are opposite to each other and spaced apart, the second weak segment and the fourth weak segment intersect at a first end, the third weak segment and the fifth weak segment intersect at a second end, the first weak segment connects the first end and the second end, and the weak point is located at the midpoint of the first weak segment.

11. The battery cell according to any one of claims 8-10, characterized in that, The at least one weak segment further includes a sixth weak segment, wherein the first weak segment and the sixth weak segment intersect at the weak point.

12. The battery cell of claim 1 or 2, wherein, The projection of the weak part onto the outer surface of the wall is a closed structure, and the closed structure surrounds the center point.

13. The battery cell of claim 1 or 2, wherein, Along the thickness direction of the wall, the center of the projection of the weak part coincides with the center point.

14. The battery cell of claim 1 or 2, wherein, Along the thickness direction of the wall portion, the center of the projection of the weak portion deviates from the center point.

15. The battery cell of claim 14, wherein the cathode comprises a lithium metal oxide. The distance B between the center of the projection of the weak part along the thickness direction and the center point satisfies: 0 < B ≤ 5 mm.

16. The battery cell of claim 15, wherein the cathode comprises a lithium metal oxide. 0 < B ≤ 3 mm.

17. The battery cell of claim 1 or 2, wherein, The wall portion includes a body portion, and the weak portion is integrally formed with the body portion.

18. The battery cell of claim 17, wherein, The hardness of the weak part is greater than the hardness of the main body.

19. The battery cell of claim 1 or 2, wherein, The wall portion includes a body portion and a pressure relief mechanism. The pressure relief mechanism is separately disposed and connected to the body portion. The weak portion is disposed on the pressure relief mechanism. The outer surface of the body portion is the outer surface of the wall portion.

20. The battery cell as described in claim 1 or 2, characterized in that, The outer casing includes: The shell has an opening; End cap, which closes the opening and is fixed to the housing; The wall portion is one wall of the end cap or the housing.

21. A battery, characterized by Includes the battery cell as described in any one of claims 1-20.

22. An electrical device, comprising: Includes the battery as described in claim 21, the battery being used to provide electrical power to the electrical device.

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