Battery cell, battery device, and electric device

Abstract

The present application discloses a battery cell, a battery device, and an electric device. The battery cell comprises a casing, an electrode assembly, and an end cover; the casing is provided with an opening; the electrode assembly is arranged inside the casing; the end cover covers the opening of the casing, and the end cover comprises a cover body, a pressure relief mechanism, and a protruding portion; the pressure relief mechanism is arranged on the cover body; the protruding portion protrudes towards the electrode assembly relative to the cover body, and the protruding portion is provided with a plurality of communication holes; the plurality of communication holes are communicated with each other to form an exhaust channel that allows gas to flow to the pressure relief mechanism; and the melting point or glass transition temperature of the protruding portion is greater than 200°C. The present application can improve the reliability of the battery cell.

Description

Battery cells, battery packs and electrical devices

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411997180.5, filed on December 31, 2024, entitled “Battery Cell, Battery Device and Power Consumption Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, and in particular to a battery cell, a battery device, and an electrical device. Background Technology

[0004] In recent years, with the rapid development of new energy technologies, new energy vehicles have been increasingly widely used and are gradually replacing traditional fuel vehicles, becoming one of the mainstream modes of transportation. As the power source of new energy vehicles, the power battery is one of their core components; therefore, the safety performance of the power battery has become a key focus of attention.

[0005] In the development of battery technology, improving the reliability of individual battery cells is a key research direction. Summary of the Invention

[0006] This application provides a battery cell, a battery device, and an electrical device that can improve the reliability of the battery cell.

[0007] In a first aspect, embodiments of this application provide a battery cell, which includes a housing, an electrode assembly, and an end cap. The housing has an opening; the electrode assembly is disposed inside the housing; the end cap is disposed over the opening of the housing, and the end cap includes a cover body, a pressure relief mechanism, and a protrusion. The pressure relief mechanism is disposed on the cover body, and the protrusion protrudes towards the electrode assembly relative to the cover body. The protrusion has multiple connecting holes, which are interconnected to form an exhaust channel for gas to flow to the pressure relief mechanism. The melting point or glass transition temperature of the protrusion is greater than 200°C.

[0008] In the above scheme, if a battery cell experiences thermal runaway, the protrusion is less likely to melt due to high temperatures because its melting point or glass transition temperature is greater than 200°C. The protrusion can prevent the electrode assembly from moving upwards, allowing gas at the bottom of the battery cell to pass through an exhaust channel formed by multiple connecting holes along the side of the battery cell. At the same time, it can prevent blockage of the pressure relief mechanism to a certain extent, ensuring that the gas can be discharged smoothly from the pressure relief mechanism. This can avoid problems such as weld cracking and casing damage caused by excessive gas pressure in the battery cell to a certain extent. The exhaust channel formed by the connecting holes can also provide storage space for gas generated during battery cell aging, reducing the internal gas pressure during the aging process and improving the reliability of the battery cell.

[0009] In some embodiments, the protrusion includes two first protruding sub-parts, which are respectively disposed at both ends of the cover body along the length direction of the battery cell; the first protruding sub-part includes a first bottom wall and a first side wall that is circumferentially disposed along the first bottom wall, and the connecting hole includes first connecting sub-holes respectively disposed on opposite sides of the first side wall along the length direction.

[0010] In the above solution, by providing first protruding sub-parts at both ends of the cover along the length direction, it can ensure to a certain extent that the gas at the bottom of the battery cell can pass through the first connecting sub-holes from both sides along the length direction and then be discharged by the pressure relief mechanism. It can also provide more storage space for the gas generated by the aging of the battery cell and further improve the reliability of the battery cell.

[0011] In some embodiments, the width of the first protruding sub-part along the length direction is D1, and the width of the battery cell along the length direction is D2, where D1 and D2 satisfy: 0.03≤D1 / D2≤0.15.

[0012] In the above solution, by limiting the width ratio of the first protruding sub-part and the battery cell along the length direction to a suitable range, neither the venting effect of the battery cell nor the space at the top of the battery cell will be affected.

[0013] In some embodiments, D1 and D2 satisfy: 0.05 ≤ D1 / D2 ≤ 0.12.

[0014] In the above scheme, by further limiting the ratio of D1 to D2, the exhaust effect of the battery cell can be further improved.

[0015] In some embodiments, the protrusion further includes a second protruding sub-part, the projection of the second protruding sub-part overlapping at least partially with the projection of the pressure relief mechanism along the height direction of the battery cell; the second protruding sub-part includes a second bottom wall and a second side wall arranged circumferentially around the second bottom wall, and the connecting hole further includes second connecting sub-holes respectively disposed on opposite sides of the second side wall along the length direction.

[0016] In the above solution, by providing a second protruding sub-part below the pressure relief mechanism, the risk of the pressure relief mechanism being blocked can be reduced. By providing second connecting sub-holes on opposite sides of the second sidewall of the second protruding part along the length direction, gas from the bottom of the battery cell can enter the top of the battery cell from the side and then be smoothly discharged through the second connecting sub-holes by the pressure relief mechanism.

[0017] In some embodiments, the width of the second protruding sub-part along the length direction is D3, and the width of the battery cell along the length direction is D2, wherein D3 and D2 satisfy: 0.12≤D3 / D2≤0.3.

[0018] In the above solution, by limiting the width of the second protruding part and the battery cell along the length direction to a suitable range, neither the venting effect of the battery cell nor the space at the top of the battery cell will be affected.

[0019] In some embodiments, D3 and D2 satisfy: 0.15≤D3 / D2≤0.3.

[0020] In the above scheme, by further limiting the ratio of D3 to D2, the exhaust effect of the battery cell can be further improved.

[0021] In some embodiments, the protrusion has an exhaust port on the side facing the electrode assembly, and the exhaust port is in communication with the connecting hole.

[0022] In the above scheme, the vent helps the gas on top of the battery cell to pass through when thermal runaway occurs, and then be discharged by the pressure relief mechanism. It also helps to store the gas on top of the battery cell when the battery cell ages.

[0023] In some embodiments, the protrusion has multiple vent holes along the width direction of the battery cell, which can improve venting efficiency.

[0024] In some embodiments, the vent hole is circular in shape.

[0025] In the above scheme, by selecting circular vent holes, it is possible to avoid the portion between adjacent vent holes being inserted between the electrode and the separator to a certain extent, thereby further improving the reliability of the battery cell.

[0026] In some embodiments, the material of the protrusion includes at least one of metal, polymer, and ceramic.

[0027] In the above scheme, materials with high melting point or high glass transition temperature are used to prepare the protrusions, which can ensure to a certain extent that the protrusions will not melt when the battery cell experiences thermal runaway.

[0028] In some embodiments, the material of the protrusion includes metal, and the outer surface of the protrusion is coated with an insulating layer.

[0029] In the above solution, by insulating the outer surface of the protrusion, the risk of arcing during the upward process of the electrode assembly can be reduced.

[0030] In some embodiments, the protrusion is provided with reinforcing ribs inside.

[0031] In the above solution, the supporting effect of the protrusion can be improved by setting reinforcing ribs inside the protrusion.

[0032] In some embodiments, the total area of ​​the connecting holes on any side of the protrusion along the length direction is S1, and the area of ​​the side is S2, where S1 and S2 satisfy: 0.15≤S1 / S2≤0.8.

[0033] In the above scheme, by limiting the area ratio of the connecting hole on any side of the protrusion along the length direction, the venting effect of the battery cell can be improved, and the support effect of the protrusion can be guaranteed to a certain extent.

[0034] In some embodiments, S1 and S2 satisfy: 0.3≤S1 / S2≤0.75.

[0035] In the above scheme, by further limiting the area ratio of the connecting hole on any side of the protrusion along the length direction of the battery cell, the venting effect and support effect of the battery cell can be further balanced.

[0036] In some embodiments, there are multiple protrusions, which are spaced apart along the length direction. The distance between adjacent protrusions is D4, where D4 satisfies: 10mm≤D4≤90mm.

[0037] In the above scheme, by limiting the spacing between adjacent protrusions along the length direction, the support and ventilation effects of the protrusions can be guaranteed to a certain extent, without affecting the space at the top of the battery cell.

[0038] Secondly, embodiments of this application also provide a battery device, including a battery cell of any of the above embodiments.

[0039] Thirdly, embodiments of this application also provide an electrical device, including the aforementioned battery device, which is used to provide electrical energy.

[0040] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0041] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 is a schematic diagram of the vehicle structure according to some embodiments of this application;

[0043] Figure 2 is an exploded view of a battery device according to some embodiments of this application;

[0044] Figure 3 is a schematic diagram of the structure of a battery module according to some embodiments of this application;

[0045] Figure 4 is an exploded structural diagram of a battery cell according to some embodiments of this application;

[0046] Figure 5 is an exploded view of a battery cell according to some embodiments of this application;

[0047] Figure 6 is a top view of the end cap of some embodiments of this application;

[0048] Figure 7 is a side view of the end cap of some embodiments of this application;

[0049] Figure 8 is a side view of the end cap of some other embodiments of this application;

[0050] Figure 9 is a side view of the end cap of some embodiments of this application;

[0051] Figure 10 is a cross-sectional view of the end cap of some embodiments of this application;

[0052] Figure 11 is a top view of the end cap of some other embodiments of this application;

[0053] Figure 12 is a top view of the end cap of some embodiments of this application;

[0054] Figure 13 is a schematic diagram of the protrusions in some embodiments of this application;

[0055] Figure 14 is a schematic diagram of the protrusions in some other embodiments of this application.

[0056] Explanation of reference numerals in the attached drawings: 1000, vehicle; 100, battery device; 200, controller; 300, motor; 10, top cover; 30, housing; 400, battery module; 20, battery cell; 22, casing; 21, end cap; 23, electrode assembly; 26, electrode terminal; 40, cover; 41, insulating component; 50, pressure relief mechanism; 60, protrusion; 61, connecting hole; 611, first connecting sub-hole; 612, second connecting sub-hole; 62, first protruding sub-part; 621, first bottom wall; 622, first side wall; 63, second protruding sub-part; 631, second bottom wall; 632, second side wall; 64, vent; 65, insulating layer; 66, reinforcing rib; X, length direction; Y, width direction. Detailed Implementation

[0057] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0058] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0059] In this application, the reference to "embodiment" means that a specific 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 throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0060] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0061] In this application, the battery cell may include a lithium-ion secondary battery cell, a lithium-ion primary battery cell, a lithium-sulfur battery cell, a sodium-lithium-ion battery cell, a sodium-ion battery cell, or a magnesium-ion battery cell, etc., and the embodiments of this application are not limited thereto. The battery cell may be cylindrical, flat, cuboid, or other shapes, etc., and the embodiments of this application are not limited thereto. Battery cells are generally classified into three types according to their packaging method: cylindrical battery cells, cuboid / square battery cells, and pouch battery cells, and the embodiments of this application are not limited thereto.

[0062] The battery device mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0063] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells into a single module. As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0064] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cell assemblies housed within the housing.

[0065] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0066] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0067] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0068] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.

[0069] Please refer to Figure 1, which is a schematic diagram of the vehicle structure 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. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle, etc. A battery device 100 is installed inside the vehicle 1000, and the battery device 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, the battery device 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 device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0070] In some embodiments of this application, the battery device 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.

[0071] Please refer to Figure 2, which is an exploded view of the device provided in some embodiments of this application. The battery device 100 includes a battery housing and a battery cell 20. In some embodiments, the battery housing may include a top cover 10 and a housing 30, with the top cover 10 and the housing 30 covering each other, and the top cover 10 and the housing 30 together defining a receiving cavity for accommodating the battery cell 20. The housing 30 may be a hollow structure with one end open, and the top cover 10 may be a plate-like structure, with the top cover 10 covering the open side of the housing 30 so that the top cover 10 and the housing 30 together define the receiving cavity; the top cover 10 and the housing 30 may also be hollow structures with one side open, with the open side of the top cover 10 covering the open side of the housing 30. Of course, the battery housing formed by the top cover 10 and the housing 30 may be of various shapes, such as a cylinder, a cuboid, etc.

[0072] Figure 3 is a schematic diagram of the structure of a battery module according to some embodiments of this application. In the battery device 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. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed manner, and then the whole formed by the multiple battery cells 20 is housed in a housing. Of course, the battery device 100 can also be in the form of multiple battery cells 20 first connected in series, parallel, or in a mixed manner to form a battery module 400, and then multiple battery modules 400 are connected in series, parallel, or in a mixed manner to form a whole and housed in a housing. The battery device 100 may also include other structures. For example, the battery device 100 may also include a busbar component for realizing the electrical connection between multiple battery cells 20.

[0073] 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.

[0074] End cap 21 refers to a component that covers the opening of housing 22 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 21 can be adapted to the shape of housing 22 to fit it. Optionally, end cap 21 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 21 is not easily deformed under pressure and impact, allowing battery cell 20 to have higher structural strength and improved safety performance. Functional components such as electrode terminals 26 can be provided on end cap 21. Electrode terminals 26 can be used for electrical connection with electrode assembly 23 to output or input electrical energy to battery cell 20. In some embodiments, end cap 21 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of battery cell 20 reaches a threshold. The material of end cap 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose any special limitations on this. In some embodiments, an insulating element may be provided on the inner side of the end cap 21. The insulating element can be used to isolate the electrical connection components within the housing 22 from the end cap 21 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.

[0075] When thermal runaway occurs inside the casing of a battery cell, a large amount of gas is generated inside the casing, causing a sharp increase in internal pressure. The pressure relief mechanism on the end cap opens, allowing the gas to be discharged to the outside. However, because the insulation of the end cap softens and melts at high temperatures, the electrode assembly moves upward with the airflow and blocks the exhaust channel. This prevents gas at the bottom of the battery cell from entering the top of the battery cell from the side (in severe cases, it can block the explosion-proof valve, significantly reducing the pressure relief area or even making it completely zero). Consequently, the gas cannot be discharged through the pressure relief mechanism, leading to internal pressure buildup in the battery cell. This can cause the weak points of the battery cell to be breached, resulting in an explosion and fire, thus reducing the reliability of the battery cell.

[0076] To address the aforementioned technical problems, this application provides a battery cell comprising a housing, an electrode assembly, and an end cap. The housing has an opening; the electrode assembly is disposed inside the housing; the end cap covers the opening of the housing and includes a cover body, a pressure relief mechanism, and a protrusion. The pressure relief mechanism is disposed on the cover body, and the protrusion protrudes towards the electrode assembly relative to the cover body. The protrusion has multiple connecting holes that are interconnected to form an exhaust channel for gas to flow to the pressure relief mechanism. The melting point or glass transition temperature of the protrusion is greater than 200°C.

[0077] In the above scheme, if a battery cell experiences thermal runaway, the protrusion is less likely to melt due to high temperatures because its melting point or glass transition temperature is greater than 200°C. The protrusion can prevent the electrode assembly from moving upwards, allowing the gas at the bottom of the battery cell to pass through the exhaust channel formed by multiple connecting holes along the side of the battery cell's length direction. At the same time, it can prevent the pressure relief mechanism from becoming blocked to a certain extent, ensuring that the gas is smoothly discharged from the pressure relief mechanism. This can avoid problems such as weld cracking and casing damage caused by excessive gas pressure in the battery cell to a certain extent. The exhaust channel formed by the connecting holes can also provide storage space for the gas generated by the aging of the battery cell, reducing the internal gas pressure during the aging process and improving the reliability of the battery cell.

[0078] Figure 5 is an exploded view of a battery cell according to some embodiments of this application; Figure 6 is a top view of an end cap according to some embodiments of this application.

[0079] Referring to Figures 5 and 6, in a first aspect, embodiments of this application provide a battery cell 20, which includes a housing 22, an electrode assembly 23, and an end cap 21. The housing 22 has an opening; the electrode assembly 23 is disposed inside the housing 22; the end cap 21 covers the opening of the housing 22 and includes a cover body 40, a pressure relief mechanism 50, and a protrusion 60. The pressure relief mechanism 50 is disposed on the cover body 40, and the protrusion 60 protrudes from the cover body 40 toward the electrode assembly 23. The protrusion 60 has multiple connecting holes 61, which are interconnected to form an exhaust channel for gas to flow to the pressure relief mechanism 50. The melting point or glass transition temperature of the protrusion 60 is greater than 200°C.

[0080] The cover 40 can be made of the same material as the housing 22, such as aluminum or steel. An insulating element 41 can be provided on the side of the cover 40 facing the electrode assembly 23 to isolate the electrode assembly 23 inside the housing 22 from the cover 40, thereby reducing the risk of short circuits. The insulating element 41 also effectively supports the end face of the electrode assembly 23. Since the electrode assembly 23 is slightly compressed after being installed in the housing and the end cap 21 is welded, insufficient compression can easily affect the core life or cause a short circuit. Therefore, the insulating element 41 needs to effectively support the end face of the electrode assembly 23 to reduce the possibility of vertical movement of the electrode assembly 23.

[0081] The end cap 21 and the housing 22 can be manufactured by welding. The welding position of the end cap 21 and the housing 22 has a weld, or there may be welds in other parts of the housing 22.

[0082] The pressure relief mechanism 50 can be a pressure valve type, containing an elastic component (such as a spring) and a sealing structure. Under normal circumstances, the spring force keeps the sealing structure closed, preventing gas leakage from the battery. When the pressure exceeds the spring's resistance, the sealing structure is forced open, and the gas is released through a designated channel. Alternatively, the pressure relief mechanism 50 can utilize material properties. For example, it can employ a fracture-resistant weak point; when the pressure reaches the weak point's limit, it ruptures, releasing the gas.

[0083] The protrusion 60 may be made of metal, with an insulating material coated on its outer surface; alternatively, the protrusion 60 may also be made of insulating material. The protrusion 60 may be fixed to the cover 40, or it may be a separate, independent component from the cover 40. The protrusion 60 may be located below the pressure relief mechanism 50, and / or at the end of the pressure relief mechanism 50 along its length X.

[0084] The protrusion 60 can be made of materials with high melting points or high glass transition temperatures, such as aluminum, steel, polyimide, or alumina ceramic. When the battery cell 20 experiences thermal runaway, the protrusion 60 is less likely to melt and can still provide downward resistance to the electrode assembly 23. The protrusion 60 can be a hollow structure with a connecting hole 61 on its sidewall to form an exhaust channel. Alternatively, the protrusion 60 can be a solid structure with a connecting hole 61 penetrating through it to form an exhaust channel.

[0085] Melting point is the temperature at which a substance changes from a solid to a liquid state. Glass transition temperature is primarily used to describe a property of amorphous polymers (such as plastics). When the temperature is below the glass transition temperature, the polymer is in a glassy state, where the movement of molecular chains is greatly restricted, and the material exhibits hard and brittle properties. When the temperature rises above the glass transition temperature, the polymer enters a highly elastic state, the molecular chains can move, and the material exhibits elasticity.

[0086] Differential scanning calorimetry (DSC) can be used to measure the melting point or glass transition temperature of the protrusion 60. The DSC instrument can simultaneously heat both the sample and the reference. When the sample undergoes a phase transition such as melting, it absorbs heat, and the DSC detects the difference in heat flow between the sample and the reference. An endothermic peak appears at the melting point; the melting point can be determined by analyzing the temperature corresponding to this endothermic peak. During the glass transition, the sample's heat capacity changes, resulting in a step-like change on the DSC curve. The glass transition temperature can be determined by analyzing the temperature range corresponding to this step.

[0087] It should be noted that if the protrusion 60 includes multiple mixed materials, the melting point or glass transition temperature of the protrusion 60 shall be referenced to the material with the lowest melting point or glass transition temperature, that is, the melting point or glass transition temperature of the material that begins to melt first.

[0088] In the above scheme, if the battery cell 20 experiences thermal runaway, since the melting point or glass transition temperature of the protrusion 60 is greater than 200°C, the protrusion 60 is not easily melted by high temperature. The protrusion 60 can prevent the electrode assembly 23 from moving upward, and can allow the gas at the bottom of the battery cell 20 to pass through the exhaust channel formed by multiple connecting holes 61 along the side of the battery cell 20. At the same time, it can prevent the pressure relief mechanism 50 from being blocked to a certain extent, ensuring that the gas is discharged from the pressure relief mechanism 50. To a certain extent, it can avoid the problem of the battery cell 20 cracking due to excessive gas pressure, such as the weld cracking and the shell 22 being damaged. The exhaust channel formed by the connecting holes 61 can also provide storage space for the gas generated by the aging of the battery cell 20, reduce the internal gas pressure during the aging process, and improve the reliability of the battery cell 20.

[0089] Figure 6 is a top view of an end cap according to some embodiments of the present application; Figure 7 is a side view of an end cap according to some embodiments of the present application.

[0090] Referring to Figures 6 and 7, in some embodiments, the protrusion 60 includes two first protruding sub-parts 62, which are respectively disposed at both ends of the cover 40 along the length direction X of the battery cell 20; the first protruding sub-part 62 includes a first bottom wall 621 and a first side wall 622 arranged circumferentially around the first bottom wall 621, and the connecting hole 61 includes first connecting sub-holes 611 respectively disposed on opposite sides of the first side wall 622 along the length direction X.

[0091] Figure 7 is a side view of the end cap of some embodiments of the present application; Figure 8 is a side view of the end cap of some other embodiments of the present application; Figure 9 is a side view of the end cap of some yet other embodiments of the present application.

[0092] The first protruding part 62 can be a cuboid, cube, ellipse, or other shapes. Referring to Figures 7-9, the first connecting hole 611 can be a circle, rectangle, square, trapezoid, or inverted trapezoid.

[0093] One or more first connecting holes 611 may be provided on the side of the first protruding sub-part 62 along the length direction X. The two first protruding sub-parts 62 are respectively provided on both sides of the pressure relief mechanism 50. When the battery cell 20 experiences thermal runaway, the bottom gas moves upward from the bottom through the side, then passes through the first connecting hole 611 of the first protruding sub-part 62, enters the top of the electrode assembly 23, and is finally discharged through the pressure relief mechanism 50.

[0094] The first connecting holes 611 on opposite sides of the first side 622 along the length direction X can be arranged directly opposite each other on a horizontal line, or they can be arranged in a staggered manner, as long as gas can pass through the first protruding part 62.

[0095] The first bottom wall 621 and the first side wall 622 can be enclosed to form a hollow structure, and the first connecting sub-hole 611 of the first side wall 622 communicates with the hollow structure inside the first protruding part 62. Alternatively, the first bottom wall 621 and the first side wall 622 can be enclosed to form a solid structure, with an exhaust channel penetrating the first protruding part 62 inside. The exhaust channel can be a horizontal channel extending along the length direction X, or it can be a curved channel.

[0096] The first bottom wall 621 serves as the basic structural part of the first protruding sub-part 62. Firstly, it connects to the first sidewall 622, making the entire first protruding sub-part 62 a relatively independent and stable structure. Secondly, a certain space is maintained between the first bottom wall 621 and the electrode assembly 23. This space can act as a temporary gas buffer area when the battery cell 20 generates gas. For example, when the battery first starts generating gas and the gas volume is small, the gas can first briefly accumulate in this small space enclosed by the first bottom wall 621 and the electrode assembly 23, and then flow orderly through the first connecting hole 611 on the first sidewall 622 to the exhaust channel, avoiding a rapid impact of the gas on the connecting hole 61 at the beginning, thus helping to maintain the stability of gas discharge. The first sidewall 622 is arranged circumferentially around the first bottom wall 621, constructing a relatively closed side structure.

[0097] The first protruding sub-parts 62 at both ends are equivalent to two key "drainage points" in the length direction X of the battery cell 20, which allows the gas at the bottom to converge in these two directions more evenly, thus avoiding the situation where the gas accumulates locally and causes excessive local pressure.

[0098] In the above scheme, by providing first protruding sub-parts 62 at both ends of the cover 40 along the length direction X, it can ensure to a certain extent that the gas at the bottom of the battery cell 20 can pass through the first connecting sub-holes 611 from both sides along the length direction X and then be discharged by the pressure relief mechanism 50. It can also provide more storage space for the gas generated by the aging of the battery cell 20, further improving the reliability of the battery cell 20.

[0099] In some embodiments, the width of the first protruding sub-part 62 along the length direction X is D1, and the width of the battery cell 20 along the length direction X is D2, where D1 and D2 satisfy: 0.03≤D1 / D2≤0.15.

[0100] The ratio of the width D1 of the first protruding sub-part 62 along the length direction X to the width D2 of the battery cell 20 along the length direction X can be any value between 0.03 and 0.12. For example, D1 / D2 can be 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.12, etc.

[0101] When D1 / D2 ≥ 0.03, the size of the first protruding sub-part 62 will not be too narrow, and it can provide sufficient support for the internal components of the battery cell 20, ensuring to a certain extent that the electrode assembly 23 will not jump up and block the pressure relief mechanism 50 during the exhaust process. For example, the first protruding sub-part 62 has more space to support the electrode assembly 23, and the surface pressure it bears is relatively small, which ensures the structural support to a certain extent. At the same time, the electrode assembly 23 is not easy to break or jump up, and the gas can be discharged quickly and smoothly.

[0102] When D1 / D2≤0.12, the first protruding sub-part 62 will not excessively encroach on the top space. For example, the first protruding sub-part 62 will not extend excessively in the length direction X, squeezing the space originally reserved for other components, making it difficult to install or perform other operations on these components.

[0103] In the above solution, by limiting the width ratio of the first protruding sub-part 62 and the battery cell 20 along the length direction X to a suitable range, neither the exhaust effect of the battery cell 20 nor the space at the top of the battery cell 20 will be affected.

[0104] In some embodiments, D1 and D2 satisfy: 0.05 ≤ D1 / D2 ≤ 0.12.

[0105] The ratio of the width D1 of the first protruding sub-part 62 along the length direction X to the width D2 of the battery cell 20 along the length direction X can be any value between 0.05 and 0.12. For example, D1 / D2 can be 0.05, 0.055, 0.065, 0.075, 0.085, 0.095, 0.11, 0.12, etc.

[0106] In the above scheme, by further limiting the ratio of D1 to D2, the exhaust effect of the battery cell 20 can be further improved.

[0107] Figure 10 is a cross-sectional view of the end cap of some embodiments of this application.

[0108] As shown in FIG10, in some embodiments, the protrusion 60 further includes a second protrusion sub-part 63, the projection of the second protrusion sub-part 63 at least partially overlaps with the projection of the pressure relief mechanism 50 along the height direction of the battery cell 20; the second protrusion sub-part 63 includes a second bottom wall 631 and a second side wall 632 arranged circumferentially around the second bottom wall 631, and the connecting hole 61 further includes second connecting sub-holes 612 respectively provided on opposite sides of the second side wall 632 along the length direction X.

[0109] The second protruding part 63 can be a cuboid, cube, ellipse, or other shapes. The first connecting hole 611 can be a circle, rectangle, square, trapezoid, or inverted trapezoid.

[0110] One or more first connecting holes 611 may be provided on the side of the second protruding sub-part 63 along the length direction X. The second protruding sub-part 63 may be located directly below the pressure relief mechanism 50, or it may be located diagonally below the pressure relief mechanism 50. When the battery cell 20 experiences thermal runaway, the bottom gas moves upward from the bottom through the side, then passes through the first connecting hole 611 of the first protruding sub-part 62, enters the area above the electrode assembly 23, then enters the second connecting hole 612, and finally is discharged through the pressure relief mechanism 50.

[0111] The second connecting holes 612 on opposite sides of the second side 632 along the length direction X can be arranged directly opposite each other on a horizontal line, or they can be arranged in a staggered manner, as long as gas can pass through the second protruding part 63.

[0112] The second bottom wall 631 and the second side wall 632 can be enclosed to form a hollow structure, and the second connecting hole 612 of the second side wall 632 communicates with the hollow structure inside the second protruding part 63. Alternatively, the second bottom wall 631 and the second side wall 632 can be enclosed to form a solid structure, with an exhaust channel penetrating the second protruding part 63 inside. The exhaust channel can be a horizontal channel extending along the length direction X, or it can be a curved channel.

[0113] The second bottom wall 631 serves as the basic structural part of the second protruding sub-part 63. Firstly, it connects to the second sidewall 632, making the entire second protruding sub-part 63 a relatively independent and stable structure. Secondly, a certain gap is maintained between the second bottom wall 631 and the electrode assembly 23; this space can act as a temporary gas buffer area when the battery cell 20 generates gas. The second sidewall 632 is arranged circumferentially around the second bottom wall 631, forming a relatively closed side structure.

[0114] In the above solution, by providing a second protruding part 63 below the pressure relief mechanism 50, the risk of the pressure relief mechanism 50 being blocked can be reduced. By providing second connecting holes 612 on opposite sides of the second sidewall 632 of the second protruding part 60 along the length direction X, gas at the bottom of the battery cell 20 can enter the top of the battery cell 20 from the side and then be smoothly discharged through the second connecting holes 612 from the pressure relief mechanism 50.

[0115] In some embodiments, the width of the second protruding sub-part 63 along the length direction X is D3, and the width of the battery cell 20 along the length direction X is D2, where D3 and D2 satisfy: 0.12≤D3 / D2≤0.3.

[0116] The ratio of the width D3 of the second protruding sub-part 63 along the length direction X to the width D2 of the battery cell 20 along the length direction X can be any value between 0.12 and 0.3. For example, D3 / D2 can be 0.12, 0.15, 0.17, 0.075, 0.085, 0.095, 0.11, 0.3, etc.

[0117] When D3 / D2 ≥ 0.12, the size of the second protruding sub-part 63 will not be too narrow, and it can provide sufficient support for the electrode assembly 23, ensuring that the battery assembly does not jump up and block the pressure relief mechanism 50 during the exhaust process. For example, the second protruding sub-part 63 has more space to support the electrode assembly 23, and the surface pressure it bears is relatively small, which ensures the structural support to a certain extent. At the same time, the electrode assembly 23 is not easy to break or jump up, and the gas can be discharged quickly and smoothly.

[0118] When D1 / D2≤0.12, the second protruding part 63 will not excessively encroach on the top space. For example, the second protruding part 63 will not extend excessively in the length direction X, squeezing the space originally reserved for other parts, making it difficult to install or perform other operations on these parts.

[0119] In the above solution, by limiting the width of the second protruding sub-part 63 and the battery cell 20 along the length direction X to a suitable range, neither the exhaust effect of the battery cell 20 nor the space at the top of the battery cell 20 will be affected.

[0120] In some embodiments, D3 and D2 satisfy: 0.15≤D3 / D2≤0.3.

[0121] The ratio of the width D3 of the second protruding sub-part 63 along the length direction X to the width D2 of the battery cell 20 along the length direction X can be any value between 0.15 and 0.3. For example, D3 / D2 can be 0.15, 0.16, 0.18, 0.2, 0.21, 0.22, 0.25, 0.3, etc.

[0122] In the above scheme, by further limiting the ratio of D3 to D2, the exhaust effect of the battery cell 20 can be further improved.

[0123] Figure 11 is a top view of an end cap according to some other embodiments of the present application; Figure 12 is a top view of an end cap according to yet another embodiment of the present application.

[0124] Referring to Figures 11 and 12, in some embodiments, the protrusion 60 is provided with an exhaust hole 64 on the side facing the electrode assembly 23, and the exhaust hole 64 is in communication with the connecting hole 61.

[0125] An exhaust hole 64 may be provided at the bottom of the first protruding part 62, and / or at the bottom of the second protruding part 63. The exhaust hole 64 may be circular, rectangular, square, trapezoidal, or inverted trapezoidal in shape.

[0126] When a battery cell 20 experiences thermal runaway, the gas at the top of the battery cell 20 can directly enter the protrusion 60 through the vent 64, pass through the connecting hole 61 into the gap between the protrusions 60, and then be discharged by the pressure relief mechanism 50.

[0127] For example, if an exhaust port 64 is provided at the bottom of the first protruding sub-part 62, the gas at both ends of the top of the battery cell 20 along the length direction X can enter the first protruding sub-part 62 through the exhaust port 64 of the first protruding sub-part 62, and then be discharged through the first connecting sub-hole 611 to the gap between the electrode assembly 23 and the end cap 21, and finally be discharged by the pressure relief mechanism 50.

[0128] Alternatively, an exhaust port 64 is provided at the bottom of the second protruding sub-part 63, so that the gas at the top of the battery cell 20 corresponding to the pressure relief mechanism 50 enters the second protruding sub-part 63 through the exhaust port 64 and is then discharged directly through the pressure relief mechanism 50.

[0129] In the above scheme, the vent 64 helps the gas at the top of the battery cell 20 to pass through when thermal runaway occurs, and then be discharged by the pressure relief mechanism 50. It also helps to store the gas at the top of the battery cell 20 when the battery cell 20 ages.

[0130] In some embodiments, the protrusion 60 is provided with a plurality of vent holes 64 along the width direction Y of the battery cell 20.

[0131] Multiple vent holes 64 are arranged at intervals along the width direction Y. The multiple vent holes 64 may have the same shape and / or different dimensions.

[0132] In the above scheme, by providing multiple vent holes 64 along the width direction Y of the battery cell 20 in the protrusion 60, the venting efficiency can be improved.

[0133] In some embodiments, the exhaust port 64 is circular in shape.

[0134] If the vent 64 is rectangular or square, the portion between adjacent vent 64s will also be rectangular. This rectangular portion is more likely to insert between the electrode and the separator during battery assembly and use due to vibration, displacement, or other factors. This could damage the integrity of the separator and lead to serious malfunctions such as internal short circuits. In contrast, the circular vent 64 has no sharp edges or corners, and its circumferential curvature makes it less likely to insert between the electrode and the separator, thus effectively protecting the internal structure of the battery and maintaining its normal electrical performance.

[0135] In the above scheme, by selecting a circular vent hole 64, it is possible to avoid the portion between adjacent vent holes 64 being inserted between the electrode and the separator to a certain extent, thereby further improving the reliability of the battery cell 20.

[0136] In some embodiments, the material of the protrusion 60 includes at least one of metal, polymer, and ceramic.

[0137] For example, the protrusion 60 may be made of aluminum with a melting point of 660°C, steel with a melting point of 1500°C, polyimide with a glass transition temperature of 400°C, or alumina ceramic material with a melting point of 1600°C.

[0138] In the above scheme, the protrusion 60 is made of a material with a high melting point or a high glass transition temperature, which can ensure to a certain extent that the protrusion 60 will not melt when the battery cell 20 experiences thermal runaway.

[0139] Figure 13 is a schematic diagram of the protrusions in some embodiments of this application.

[0140] As shown in Figure 13, in some embodiments, the material of the protrusion 60 includes metal, and the outer surface of the protrusion 60 is coated with an insulating layer 65.

[0141] Metallic materials are conductive. In the special electrical environment of the battery cell 20, the electrode assembly 23 carries a charge. When the electrode assembly 23 tends to push upward, if the protrusion 60 is not properly treated, due to the conductivity of its metal, it can easily form a conductive path with the electrode assembly 23, thereby causing a conductive arcing phenomenon. This will not only damage the battery cell 20 itself, but in severe cases, it may even lead to battery fire or explosion.

[0142] The insulating layer 65 acts as an "electrical barrier" between the protrusion 60 and the electrode assembly 23, preventing any potential conductive connection between them. When the electrode assembly 23 is pushed upwards due to internal pressure changes, thermal runaway, or other reasons, even if it comes into contact with the protrusion 60, the insulating layer 65 prevents current from being conducted between them, thereby reducing the risk of arcing.

[0143] For example, the insulating layer 65 can be formed using materials such as polyimide, ceramic coating, or epoxy resin. The outer surface of the protrusion 60 can also undergo insulating treatments such as electro-oxidation or surface coating with alumina.

[0144] In the above solution, by insulating the outer surface of the protrusion 60, the risk of arcing during the upward process of the electrode assembly 23 can be reduced.

[0145] Figure 14 is a schematic diagram of the protrusions in some other embodiments of this application.

[0146] As shown in Figure 14, in some embodiments, the protrusion 60 is provided with a reinforcing rib 66 inside.

[0147] The protrusion 60 serves to prevent the electrode assembly 23 from moving upwards and to provide a proper channel for gas discharge. If the protrusion 60 is excessively deformed due to external forces, the electrode assembly 23 may not be effectively blocked, potentially leading to a series of safety issues such as collisions between the electrode and other components, and arcing. Simultaneously, the deformed protrusion 60 may compress or block the gas discharge channels such as the connecting hole 61 and the vent hole 64, preventing smooth gas discharge and causing excessively high internal battery pressure, further threatening the safety of the battery cell 20.

[0148] The reinforcing ribs 66 can be made of high-strength materials, such as high-strength alloy steel or carbon fiber reinforced composite materials, or the reinforcing ribs 66 and the protrusion 60 can be integrally formed using the same material. These reinforcing ribs 66 are distributed within the protrusion 60 in a specific layout, such as a crisscrossing grid or strips arranged along the main stress direction. For example, multiple reinforcing ribs 66 can be spaced apart along the width Y direction of the battery cell 20, thereby dividing the protrusion 60 into multiple grooves.

[0149] When external pressure is applied to the protrusion 60, the reinforcing rib 66 can share a large part of the stress, preventing the material of the protrusion 60 from undergoing excessive bending or twisting deformation, so that the entire protrusion 60 can maintain high structural rigidity like a sturdy frame, providing stable and reliable support for the blocking electrode assembly 23.

[0150] In the above solution, by setting reinforcing ribs 66 inside the protrusion 60, the support effect of the protrusion 60 can be improved.

[0151] In some embodiments, the total area of ​​the connecting holes 61 on any side of the protrusion 60 along the length direction X is S1, and the area of ​​the side is S2, where S1 and S2 satisfy: 0.15≤S1 / S2≤0.8.

[0152] The ratio of the total area S1 of the connecting hole 61 on any side of the protrusion 60 along the length direction X to the area S2 of the side can be any value between 0.15 and 0.8. For example, S1 / S2 can be 0.15, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, or 0.8.

[0153] The protrusion 60 has two sides facing each other along its length X, each with a connecting hole 61. For example, the left and right sides of the first protrusion 62 are each provided with a first connecting hole 611. If the area of ​​all the first connecting holes 611 on the left side of the first protrusion 62 is S1, then the area of ​​the left side of the first protrusion 62 is S2; or if the area of ​​all the first connecting holes 611 on the right side of the first protrusion 62 is S1, then the area of ​​the right side of the first protrusion 62 is S2.

[0154] When S1 / S2≥0.15, the total area of ​​the connecting hole 61 will not be too small relative to the side area. In the case of a large amount of gas generated by the battery cell 20, such as during thermal runaway, will the flow rate of gas through the connecting hole 61 be restricted?

[0155] One of the main functions of the protrusion 60 is to provide support. When S1 / S2≤0.8, the setting of the connecting hole 61 will not weaken the structural strength of the side of the protrusion 60, so that it is not easy to deform when subjected to the top pressure of the electrode assembly 23 or external impact, thus not affecting its support effect.

[0156] In the above solution, by limiting the area ratio of the connecting hole 61 on any side of the protrusion 60 along the length direction X, the exhaust effect of the battery cell 20 can be improved, and the support effect of the protrusion 60 can be guaranteed to a certain extent.

[0157] In some embodiments, S1 and S2 satisfy: 0.3≤S1 / S2≤0.75.

[0158] The ratio of the total area S1 of the connecting hole 61 on any side of the protrusion 60 along the length direction X to the area S2 of the side can be any value between 0.3 and 0.75. For example, S1 / S2 can be 0.3, 0.35, 0.45, 0.55, 0.57, 0.62, 0.72, or 0.75.

[0159] In the above scheme, by further limiting the area ratio of the connecting hole 61 on any side of the protrusion 60 along the length direction X, the exhaust effect and support effect of the battery cell 20 can be further balanced.

[0160] In some embodiments, there are multiple protrusions 60, which are spaced apart along the length direction X. The distance between adjacent protrusions 60 is D4, where D4 satisfies: 10mm≤D4≤90mm.

[0161] The spacing D4 between adjacent protrusions 60 can be any value between 10mm and 90mm. For example, D4 ​​can be 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, or 90mm.

[0162] For battery cells 20 that are longer, the number of protrusions 60 can be increased appropriately.

[0163] With a diameter (D4) ≤ 90mm, the spacing between adjacent protrusions 60 is not excessive, and there are sufficient supporting structures in large areas along the length direction X. When the battery cell 20 is subjected to forces such as external impacts or uneven expansion of internal gas, these spaced areas are less prone to structural collapse or excessive deformation, ensuring the stable support of the protrusions 60 to a certain extent. Simultaneously, in the event of thermal runaway, the smaller spacing between adjacent protrusions 60 prevents the electrode assembly 23 from collapsing and rising, thus ensuring the top venting channel and preventing the battery cell 20 from catching fire or exploding to a certain extent.

[0164] When D4≥10mm, the protrusion 60 will not excessively encroach on the top space, and the gap between adjacent protrusions 60 has enough space for the placement of other components, such as not affecting the space of the adapter and the tab.

[0165] In the above scheme, by limiting the spacing between adjacent protrusions 60 along the length direction X, the support and ventilation effects of the protrusions 60 can be guaranteed to a certain extent, without affecting the space at the top of the battery cell 20.

[0166] Secondly, embodiments of this application also provide a battery device, including a battery cell 20 of any of the above embodiments.

[0167] Thirdly, embodiments of this application also provide an electrical device, including the aforementioned battery device, which is used to provide electrical energy.

[0168] According to some embodiments of this application, this application provides a battery cell 20, which includes a housing 22, an electrode assembly 23, and an end cap 21. The housing 22 has an opening; the electrode assembly 23 is disposed inside the housing 22; the end cap 21 covers the opening of the housing 22, and the end cap 21 includes a cover body 40, a pressure relief mechanism 50, and a protrusion 60. The pressure relief mechanism 50 is disposed on the cover body 40, and the protrusion 60 protrudes from the cover body 40 toward the electrode assembly 23. The protrusion 60 is provided with a plurality of connecting holes 61, which are interconnected to form an exhaust channel for gas to flow to the pressure relief mechanism 50. The melting point of the protrusion 60 is greater than 200°C. The protrusion 60 includes two first protruding sub-parts 62, which are respectively disposed at both ends of the cover 40 along the length direction X. The first protruding sub-part 62 includes a first bottom wall 621 and a first side wall 622 arranged circumferentially around the first bottom wall 621. The connecting hole 61 includes first connecting sub-holes 611 respectively disposed on opposite sides of the first side wall 622 along the length direction X.

[0169] Example

[0170] Preparation of positive electrode sheet

[0171] Lithium iron phosphate (specific capacity of 139 mAh / g), acetylene black, and PVDF (polyvinylidene fluoride) were mixed in a weight ratio of 96:2:2. N-methylpyrrolidone was added as a solvent, and the mixture was stirred thoroughly to obtain a positive electrode slurry. The slurry was then coated onto the aluminum foil of the positive electrode current collector. The coating weight of the negative electrode slurry was 0.224 g / 1540.25 mm2 (based on the weight excluding solvent). The mixture was then dried and cold-pressed to obtain the positive electrode sheet.

[0172] Preparation of negative electrode sheet

[0173] Artificial graphite (specific capacity of 340 mAh / g), conductive agent acetylene black, and binder SBR (styrene-butadiene rubber) + CMC (carboxymethyl cellulose) were mixed in a weight ratio of 95:1.5:3.1:0.4. Deionized water was added as a solvent, and the mixture was stirred thoroughly to obtain a negative electrode slurry. The slurry was then coated onto both surfaces of the copper foil current collector. The coating weight of the negative electrode slurry was 0.108 g / 1540.25 mm2 (excluding solvent). After drying and cold pressing, the negative electrode sheet was obtained.

[0174] Preparation of diaphragm

[0175] The separator uses a porous polyethylene membrane as the substrate and is coated with a double-sided ceramic coating.

[0176] Preparation of electrolyte

[0177] In an argon-atmosphere glove box with a water content of <10ppm, EC (ethylene carbonate), PC (propylene carbonate), and DMC (dimethyl carbonate) were mixed in a weight ratio of EC:PC:DMC = 3:3:3. Then, LiPF6 (lithium hexafluorophosphate), VC (ethylene carbonate), DTD (1,3-propanesulfonate lactone), and PS (ethylene sulfate) were added to the mixed organic solvent and stirred until homogeneous to obtain the electrolyte. The concentration of LiPF6 in the lithium-ion battery electrolyte was 1 mol / L, and the mass percentages of VC, DTD, and PS were 3%, 1%, and 1%, respectively.

[0178] Preparation of battery cell 20

[0179] The electrode sheets are cold-pressed and die-cut, then wound together with the separator into a core. After hot pressing, ultrasonic welding, laser welding of the electrode adapter, wrapping with insulating film, inserting into the shell, welding the shell 22 to the end cap 21, liquid injection, formation, secondary liquid injection, aging, welding of sealing nails, capacity testing and other processes, the hard-shell battery cell 20 is assembled.

[0180] Thermal runaway determination method 1 (heating trigger):

[0181] Referring to the UL9540A thermal runaway test method, the initial conditions are: temperature 25±5℃, humidity 50±25%, SOC (state of charge) 100%, and ≥2 charge-discharge cycles. The pre-test resting time t is 1-8 hours. Test conditions: External heating is performed using a flexible heating film (covering the surface of the battery cell 20 as much as possible, excluding safety components and electrode terminals 26). The surface heating rate R = 4℃~7℃ / min is applied until thermal runaway occurs in the battery cell 20 (the temperature on the side of the largest area of ​​the battery cell 20 rises sharply, typically >3℃ / s). Heating is immediately stopped after runaway, and the cell is allowed to stand for 1 hour. If the battery cell 20 explodes or catches fire, the test is considered unqualified.

[0182] Thermal runaway detection method 2 (overcharge + heating trigger):

[0183] Referring to GB / T 36276-2023 Thermal Runaway Test Method, the initial conditions are: temperature 25±5℃, SOC (State of Charge) reaching 100%. Test conditions: A flat heating film is used to heat one side of the largest area of ​​the battery cell (20 cells), while simultaneously overcharging at 0.5C until thermal runaway occurs on the largest area side (the temperature of the largest area side rises rapidly, typically >3℃ / s). Heating and overcharging are immediately stopped after runaway, and the cell is left to stand for 1 hour. If the cell explodes or catches fire, the test is considered unqualified.

[0184] Comparative Example 1

[0185] The protrusions 60 are made of polypropylene. The first protruding sub-part 62 has a circular vent 64. The first protruding sub-part 62 does not have a first connecting sub-hole 611, and the second protruding sub-part 63 does not have a second connecting sub-hole 612. The width of the first protruding sub-part 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protruding sub-part 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, which are spaced apart along the length direction X. The distance between adjacent protrusions 60 is D4, where D4 = 70 mm. The total area of ​​the vent 64 of the first protruding sub-part 62 is S1, and the area of ​​the bottom surface of the first protruding sub-part 62 is S2. S1 / S2 = 0.5. The pass rate of thermal runaway test method 1 was 0%, and the failure phenomenon was the explosion and fire of battery cell 20; the pass rate of thermal runaway test method 2 was 0%, and the failure phenomenon was the explosion and fire of battery cell 20.

[0186] Comparative Example 2

[0187] The protrusions 60 are made of polypropylene. The first protrusion 62 has a circular vent 64 and a circular first connecting hole 611. The second protrusion 63 has a circular vent 64 and a circular second connecting hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a distance of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.5. The pass rate of thermal runaway test method 1 was 10%, and the failure phenomenon was the explosion and fire of battery cell 20; the pass rate of thermal runaway test method 2 was 0%, and the failure phenomenon was the explosion and fire of battery cell 20.

[0188] Comparative Example 3

[0189] The protrusions 60 are made of aluminum. The first protruding sub-part 62 has a circular vent 64 and a circular first connecting sub-hole 611. The second protruding sub-part 63 has a circular vent 64 and a circular second connecting sub-hole 612. The width of the first protruding sub-part 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protruding sub-part 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a distance of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.5. The pass rate of thermal runaway test method 1 is 80%, and the failure phenomenon is that the battery cell 20 catches fire but does not explode; the pass rate of thermal runaway test method 2 is 60%, and the failure phenomenon is that the battery cell 20 catches fire but does not explode.

[0190] Comparative Example 4

[0191] The protrusions 60 are made of steel. The first protruding sub-part 62 has a circular vent 64 and a circular first connecting sub-hole 611. The second protruding sub-part 63 has a circular vent 64 and a circular second connecting sub-hole 612. The width of the first protruding sub-part 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protruding sub-part 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a distance of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.5. The pass rate of thermal runaway test method 1 is 90%, and the failure phenomenon is that the battery cell 20 catches fire but does not explode; the pass rate of thermal runaway test method 2 is 80%, and the failure phenomenon is that the battery cell 20 catches fire but does not explode.

[0192] Comparative Example 5

[0193] The protrusions 60 are made of polyimide. The first protrusion 62 has a circular vent 64 and a circular first connecting hole 611. The second protrusion 63 has a circular vent 64 and a circular second connecting hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a distance of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.82. The pass rate of thermal runaway test method 1 is 90%, and the failure phenomenon is the fire and explosion of battery cell 20; the pass rate of thermal runaway test method 2 is 70%, and the failure phenomenon is the fire and explosion of battery cell 20.

[0194] Comparative Example 6

[0195] The protrusions 60 are made of alumina ceramic material. The first protrusion 62 has a circular vent 64 and a circular first connecting hole 611. The second protrusion 63 has a circular vent 64 and a circular second connecting hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a distance of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.82. The pass rate of thermal runaway test method 1 is 80%, and the failure phenomenon is that the battery cell 20 does not catch fire or explode; the pass rate of thermal runaway test method 2 is 70%, and the failure phenomenon is that the battery cell 20 catches fire and explodes.

[0196] Comparative Example 7

[0197] The protrusion 60 is made of aluminum and its outer surface is electro-oxidized for insulation. The first protrusion 62 has a rectangular vent 64 and a rectangular first connecting sub-hole 611. The second protrusion 63 has a rectangular vent 64 and a rectangular second connecting sub-hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a spacing of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.5. The pass rate of thermal runaway test method 1 is 80%, and the failure phenomenon is the fire of battery cell 20; the pass rate of thermal runaway test method 2 is 70%, and the failure phenomenon is the fire of battery cell 20.

[0198] Comparative Example 8

[0199] The protrusion 60 is made of aluminum and its outer surface is electro-oxidized for insulation. The first protrusion 62 has a circular vent 64 and a circular first connecting hole 611. The second protrusion 63 has a circular vent 64 and a circular second connecting hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a distance of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.1. The pass rate of thermal runaway test method 1 was 10%, and the failure phenomenon was the fire and explosion of battery cell 20; the pass rate of thermal runaway test method 2 was 0%, and the failure phenomenon was the fire and explosion of battery cell 20.

[0200] Comparative Example 9

[0201] The protrusion 60 is made of aluminum and its outer surface is electrically anodized for insulation. The first protrusion 62 has a circular vent 64 and a circular first connecting hole 611. The second protrusion 63 has a circular vent 64 and a circular second connecting hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.01, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a distance of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.5. The pass rate of thermal runaway test method 1 is 60%, and the failure phenomenon is the fire and explosion of battery cell 20; the pass rate of thermal runaway test method 2 is 50%, and the failure phenomenon is the fire and explosion of battery cell 20.

[0202] Comparative Example 10

[0203] The protrusion 60 is made of aluminum and its outer surface is electrically anodized for insulation. The first protrusion 62 has a circular vent 64 and a circular first connecting hole 611. The second protrusion 63 has a circular vent 64 and a circular second connecting hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.02. There are multiple protrusions 60, spaced apart along the length direction X, with a distance of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.5. The pass rate of thermal runaway test method 1 is 50%, and the failure phenomenon is the fire and explosion of battery cell 20; the pass rate of thermal runaway test method 2 is 40%, and the failure phenomenon is the fire and explosion of battery cell 20.

[0204] Comparative Example 11

[0205] The protrusion 60 is made of aluminum and its outer surface is electro-oxidized for insulation. The first protrusion 62 has a circular vent 64 and a circular first connecting hole 611. The second protrusion 63 has a circular vent 64 and a circular second connecting hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a distance of D4 between adjacent protrusions 60, where D4 = 130 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.5. The pass rate of thermal runaway test method 1 is 80%, and the failure phenomenon is the fire and explosion of battery cell 20; the pass rate of thermal runaway test method 2 is 80%, and the failure phenomenon is the fire and explosion of battery cell 20.

[0206] Example 1

[0207] The protrusion 60 is made of aluminum and its outer surface is electrically anodized for insulation. The first protrusion 62 has a circular vent 64 and a circular first connecting hole 611. The second protrusion 63 has a circular vent 64 and a second connecting hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a distance of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.5. The pass rate for thermal runaway testing method 1 was 100%, and the pass rate for thermal runaway testing method 2 was 100%.

[0208] Example 2

[0209] The protrusion 60 is made of aluminum and has an aluminum oxide coating for insulation on its outer surface. The first protrusion 62 has a circular vent 64 and a circular first connecting hole 611. The second protrusion 63 has a circular vent 64 and a circular second connecting hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a distance of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.5. The pass rate for thermal runaway testing method 1 was 100%, and the pass rate for thermal runaway testing method 2 was 100%.

[0210] Example 3

[0211] The protrusion 60 is made of aluminum and its outer surface is electrically anodized for insulation. The first protrusion 62 has a circular vent 64 and an inverted trapezoidal first connecting sub-hole 611. The second protrusion 63 has a circular vent 64 and an inverted trapezoidal second connecting sub-hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a distance of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.5. The pass rate for thermal runaway testing method 1 was 100%, and the pass rate for thermal runaway testing method 2 was 100%.

[0212] Example 4

[0213] The protrusion 60 is made of alumina ceramic material. The first protrusion 62 has a circular vent 64 and a circular first connecting sub-hole 611. The second protrusion 63 has a circular vent 64 and a circular second connecting sub-hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a spacing of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.42. The pass rate for thermal runaway testing method 1 is 100%, and the pass rate for thermal runaway testing method 2 is 100%.

[0214] Example 5

[0215] The protrusions 60 are made of polyimide. The first protrusion 62 has a circular vent 64 and a circular first connecting hole 611. The second protrusion 63 has a circular vent 64 and a circular second connecting hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a spacing of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.5. The pass rate for thermal runaway testing method 1 is 100%, and the pass rate for thermal runaway testing method 2 is 100%.

[0216] Example 6

[0217] The protrusions 60 are made of polyimide. The first protrusion 62 has a circular vent 64 and a circular first connecting hole 611. The second protrusion 63 has a circular vent 64 and a circular second connecting hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.09, D3 / D2 = 0.26. There are multiple protrusions 60, spaced apart along the length direction X, with a spacing of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.6. The pass rate for thermal runaway testing method 1 is 100%, and the pass rate for thermal runaway testing method 2 is 100%.

[0218] Example 7

[0219] The protrusion 60 is made of aluminum and its outer surface is electrically anodized for insulation. The first protrusion 62 has a circular vent 64 and a circular first connecting hole 611. The second protrusion 63 has a circular vent 64 and a circular second connecting hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.15, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a distance of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.5. The pass rate for thermal runaway testing method 1 was 100%, and the pass rate for thermal runaway testing method 2 was 100%.

[0220] Example 8

[0221] The protrusion 60 is made of aluminum and its outer surface is electrically anodized for insulation. The first protrusion 62 has a circular vent 64 and a circular first connecting hole 611. The second protrusion 63 has a circular vent 64 and a circular second connecting hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.5. There are multiple protrusions 60, spaced apart along the length direction X, with a distance of D4 between adjacent protrusions 60, where D4 = 70 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.5. The pass rate for thermal runaway testing method 1 was 100%, and the pass rate for thermal runaway testing method 2 was 100%.

[0222] Example 9

[0223] The protrusion 60 is made of aluminum and its outer surface is electrically anodized for insulation. The first protrusion 62 has a circular vent 64 and a circular first connecting hole 611. The second protrusion 63 has a circular vent 64 and a circular second connecting hole 612. The width of the first protrusion 62 along the length direction X is D1, the width of the battery cell 20 along the length direction X is D2, and the width of the second protrusion 63 along the length direction X is D3. D1 / D2 = 0.08, D3 / D2 = 0.24. There are multiple protrusions 60, spaced apart along the length direction X, with a spacing of D4 between adjacent protrusions 60, where D4 = 10 mm. The total area of ​​the connecting hole 61 or vent 64 on any side of the protrusion 60 is S1, and the area of ​​the side is S2, where S1 / S2 = 0.5. The pass rate for thermal runaway testing method 1 was 100%, and the pass rate for thermal runaway testing method 2 was 100%.

[0224] From the above comparative examples and embodiments, it can be seen that if the protrusion 60 is made of a low-melting-point material and the connecting hole 61 is not provided, the battery cell 20 will fail the thermal runaway test and will explode and catch fire. If the protrusion 60 is made of a low-melting-point material and the connecting hole 61 is provided, the pass rate of the thermal runaway test for the battery cell 20 is still very low, and it is prone to explosion and fire. If the protrusion 60 is made of a high-melting-point metal material, the pass rate of the thermal runaway test for the battery cell 20 becomes higher, but if the outer surface of the metal protrusion 60 is not insulated, it is prone to fire but not explosion. If the vent 64 of the protrusion 60 is set to a circular shape, compared to a rectangular shape, the pass rate of the thermal runaway test will increase, and it will not catch fire or explode. The pass rate of thermal runaway test can be increased when any of the following conditions are met: 0.03≤D1 / D2≤0.15, 0.12≤D3 / D2≤0.3, 0.15≤S1 / S2≤0.8, 10mm≤D4≤90mm.

[0225] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A single battery cell, comprising: The casing has an opening; The electrode assembly is disposed inside the housing; An end cap is provided over the opening of the housing. The end cap includes a cover body, a pressure relief mechanism, and a protrusion. The pressure relief mechanism is disposed on the cover body. The protrusion protrudes from the cover body toward the electrode assembly. The protrusion has multiple connecting holes that are interconnected to form an exhaust channel for gas to flow to the pressure relief mechanism. The melting point or glass transition temperature of the protrusion is greater than 200°C.

2. The battery cell according to claim 1, wherein, The protrusion includes two first protruding sub-parts, which are respectively disposed at both ends of the cover body along the length direction of the battery cell. The first protruding sub-part includes a first bottom wall and a first side wall that is arranged circumferentially around the first bottom wall. The connecting hole includes first connecting sub-holes respectively disposed on opposite sides of the first side wall along the length direction.

3. The battery cell according to claim 2, wherein, The width of the first protruding sub-part along the length direction is D1, and the width of the battery cell along the length direction is D2. D1 and D2 satisfy: 0.03≤D1 / D2≤0.

15.

4. The battery cell according to claim 3, wherein, The condition D1 and D2 satisfy: 0.05≤D1 / D2≤0.

12.

5. The battery cell according to claim 2, wherein, The protrusion further includes a second protrusion sub-part, the projection of the second protrusion sub-part overlapping at least partially with the projection of the pressure relief mechanism along the height direction of the battery cell; The second protruding sub-part includes a second bottom wall and a second side wall that is arranged circumferentially around the second bottom wall. The connecting hole also includes second connecting sub-holes respectively disposed on opposite sides of the second side wall along the length direction.

6. The battery cell according to claim 5, wherein, The width of the second protruding sub-part along the length direction is D3, and the width of the battery cell along the length direction is D2. D3 and D2 satisfy: 0.12≤D3 / D2≤0.

3.

7. The battery cell according to claim 6, wherein, The condition D3 and D2 satisfy: 0.15≤D3 / D2≤0.

3.

8. The battery cell according to claim 1, wherein, The protrusion has an exhaust hole on the side facing the electrode assembly, and the exhaust hole is connected to the connecting hole.

9. The battery cell according to claim 8, wherein, The protrusion has a plurality of vent holes along the width direction of the battery cell.

10. The battery cell according to claim 9, wherein, The exhaust port is circular in shape.

11. The battery cell according to any one of claims 1-10, wherein, The material of the protrusion includes at least one of metal, polymer and ceramic.

12. The battery cell according to claim 11, wherein, The material of the protrusion includes metal, and the outer surface of the protrusion is coated with an insulating layer.

13. The battery cell according to any one of claims 1-12, wherein, The protrusion is provided with reinforcing ribs inside.

14. The battery cell according to any one of claims 1-13, wherein, The total area of ​​the connecting hole on any side of the protrusion is S1, and the area of ​​the side is S2. S1 and S2 satisfy: 0.15≤S1 / S2≤0.

8.

15. The battery cell according to claim 14, wherein, S1 and S2 satisfy the condition: 0.3≤S1 / S2≤0.

75.

16. The battery cell according to any one of claims 1-15, wherein, The number of protrusions is multiple, and the multiple protrusions are arranged at intervals along the length direction of the battery cell. The distance between adjacent protrusions is D4, and D4 satisfies: 10mm≤D4≤90mm.

17. A battery device comprising a battery cell as claimed in any one of claims 1-16.

18. An electrical device comprising the battery device according to claim 17, the battery device being used to provide electrical energy.

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