Battery cell, battery apparatus and electrical device

Abstract

Provided in the embodiments of the present application are a battery cell, a battery apparatus and an electrical device. The battery cell comprises: a casing, the casing comprising a first casing wall provided with a pressure relief mechanism; an electrode assembly, accommodated in the casing; and an insulating structure, located between the first casing wall and the electrode assembly, the insulating structure comprising a body part and a pressure relief part arranged corresponding to the pressure relief mechanism, the pressure relief part protruding towards the electrode assembly relative to the body part, the pressure relief part comprising a first bottom wall and a first side wall that intersect each other, the first bottom wall being perpendicular to the thickness direction of the first casing wall, the first side wall being perpendicular to the width direction of the first casing wall, and the surface of the first bottom wall away from the pressure relief mechanism and the surface of the first side wall away from the pressure relief mechanism being connected by means of a chamfer. The battery cell, the battery apparatus and the electrical device in the embodiments of the present application can improve the reliability of battery cells.

Description

Battery cells, battery devices and electrical equipment Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery cell, battery device, and electrical equipment. Background Technology

[0002] Energy conservation and emission reduction are crucial for the sustainable development of the automotive industry. In this context, electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of the automotive industry's sustainable development. For electric vehicles, battery technology is a critical factor in their development. In the development of battery technology, in addition to improving the performance of individual battery cells, how to improve the safety and reliability of individual battery cells is also an issue that cannot be ignored. Summary of the Invention

[0003] This application provides a battery cell, a battery device, and an electrical appliance that can improve the reliability of the battery cell.

[0004] In a first aspect, a battery cell is provided, comprising: a housing, the housing including a first housing wall having a pressure relief mechanism; an electrode assembly housed within the housing; and an insulating structure located between the first housing wall and the electrode assembly, the insulating structure including a body portion and a pressure relief portion corresponding to the pressure relief mechanism, the pressure relief portion protruding relative to the body portion toward the electrode assembly, the pressure relief portion including an intersecting first bottom wall and a first side wall, the first bottom wall being perpendicular to the thickness direction of the first housing wall, the first side wall being perpendicular to the width direction of the first housing wall, and the surfaces of the first bottom wall away from the pressure relief mechanism and the surfaces of the first side wall away from the pressure relief mechanism being connected by a chamfer.

[0005] Therefore, in the battery cell of this application embodiment, since the length dimension of the first outer casing wall is greater than the width dimension, the deformation of the width direction of the first outer casing wall is more severe when the battery cell experiences thermal runaway. Similarly, the deformation of the insulation structure in the width direction is also more severe. For example, when the battery cell experiences thermal runaway, under the influence of internal air pressure, the central region of the insulation structure, compared to the edge region, typically bulges outward toward the battery cell along the width direction of the first outer casing wall, causing its cross-section to deform into an arch shape. The chamfer provided at the intersection of the surface of the first bottom wall away from the pressure relief mechanism and the surface of the first side wall away from the pressure relief mechanism will shift and twist toward the central region. Simultaneously, the electrode assembly will also move toward the first outer casing wall under the action of air pressure. However, since a chamfer is provided between the surface of the first bottom wall away from the pressure relief mechanism and the surface of the first side wall away from the pressure relief mechanism, the chamfer is smoother than a right angle edge, which can reduce the risk of short circuit of the battery cell caused by inserting the electrode assembly at the connection between the first bottom wall and the first side wall of the pressure relief part, and thus reduce the risk of battery cell explosion, and improve the reliability of the battery cell and the battery device in which the battery cell is located.

[0006] In some embodiments, the chamfer is rounded, making the side of the pressure relief portion facing the electrode assembly smoother. In the event of thermal runaway of the battery cell, this reduces the risk of the portion of the area being inserted into and damaged by the electrode assembly, thereby reducing the risk of short circuit in the battery cell and the risk of battery cell explosion, and improving the reliability of the battery cell and the battery device in which the battery cell is located.

[0007] In some embodiments, the radius of the fillet ranges from 1 mm to 40 mm. Setting the radius of the fillet to be greater than or equal to 1 mm makes this area smoother, reducing the risk of inserting and damaging the electrode assembly in this area, and improving the reliability of the battery cell and the battery device in which the battery cell is located. However, considering the limited space between the insulation structure and the electrode assembly, the radius of the fillet should not be too large, for example, usually less than or equal to 40 mm, in order to reduce the space occupied by the pressure relief section and increase the energy density of the battery cell.

[0008] In some embodiments, the radius of the fillet is in the range of [2mm, 10mm]. This can reduce the risk of inserting and damaging the electrode assembly in this area, thereby causing a short circuit in the battery cell, and also reduce the space occupied by the pressure relief section, so as to balance the relationship between the reliability and energy density of the battery cell.

[0009] In some embodiments, the first bottom wall abuts against the end face of the electrode assembly facing the first outer casing wall to support the electrode assembly through the pressure relief portion, thereby improving the internal structural stability of the battery cell; and, in the event of thermal runaway of the battery cell, it can reduce the displacement of the electrode assembly under the action of internal air pressure, thereby improving the stability and reliability of the battery cell.

[0010] In some embodiments, the first outer casing wall is provided with a liquid injection structure, and the insulating structure further includes a liquid injection portion corresponding to the liquid injection structure. The liquid injection portion protrudes towards the electrode assembly relative to the body portion. The liquid injection portion includes a second bottom wall, which is perpendicular to the thickness direction of the first outer casing wall and is farther away from the electrode assembly than the first bottom wall. This reduces the risk of the liquid injection portion inserting into the electrode assembly due to the obstruction of the pressure relief portion, thereby reducing the risk of short circuits in the battery cell and the risk of battery cell explosion, thus improving the reliability of the battery cell and the battery device containing it.

[0011] In some embodiments, the height difference between the second bottom wall and the first bottom wall along the thickness direction of the first outer casing wall ranges from 0.2 mm to 8 mm. By setting the height difference to be greater than or equal to 0.2 mm, the risk of the liquid injection portion inserting into the electrode assembly can be reduced, thereby reducing the risk of short circuits in the battery cell and the risk of battery cell explosion, thus improving the reliability of the battery cell and the battery device in which the battery cell is located. However, the height difference should not be too large, for example, it can be set to be less than or equal to 8 mm. On the one hand, this ensures that the distance between the second bottom wall of the liquid injection portion and the first outer casing wall along the thickness direction of the first outer casing wall is not too small, thus protecting the liquid injection structure and improving the liquid injection efficiency. On the other hand, it can improve the utilization rate of the internal space of the battery cell, thereby increasing the energy density of the battery cell.

[0012] In some embodiments, the height difference between the second bottom wall and the first bottom wall along the thickness direction of the first outer casing wall ranges from [1 mm to 5 mm]. This effectively reduces the risk of inserting the electrode assembly into the liquid injection section, and also improves the liquid injection efficiency and the internal space utilization of the battery cell.

[0013] In some embodiments, the insulation structure further includes two support portions along the length of the first outer casing wall, with the pressure relief portion located between the two support portions; the two support portions protrude toward the electrode assembly relative to the body portion. The two support portions disposed on both sides of the pressure relief portion of the insulation structure along the length of the first outer casing wall can be used to support the electrode assembly, reducing movement of the electrode assembly toward the first outer casing wall and improving the structural stability of the battery cell. Especially in the event of thermal runaway in the battery cell, the two support portions can be used to support the electrode assembly, reducing movement of the electrode assembly toward the first outer casing wall under pressure, thereby reducing the risk of the pressure relief portion inserting into and damaging the electrode assembly, thus reducing the risk of short circuit in the battery cell, and consequently reducing the risk of battery cell explosion, improving the reliability of the battery cell and the battery device containing it.

[0014] In some embodiments, the two support portions are located at both ends of the insulation structure along the length of the first outer casing wall, which facilitates processing and can effectively support the electrode assembly, further improving the stability of the electrode assembly.

[0015] In some embodiments, each of the two support portions includes a third bottom wall perpendicular to the thickness direction of the first outer casing wall, and the third bottom wall abuts against the end face of the electrode assembly facing the first outer casing wall. The third bottom wall, positioned facing the electrode assembly, effectively supports the electrode assembly, improving the internal structural stability of the battery cell; furthermore, in the event of thermal runaway in the battery cell, it reduces the displacement of the electrode assembly under internal pressure, thereby improving the stability and reliability of the battery cell.

[0016] In some embodiments, along the length of the first outer casing wall, the ratio of the total length of the third bottom wall of the two supports to the total length of the electrode assembly ranges from [1 / 20, 1 / 2]. A ratio greater than or equal to 1 / 20 allows the two supports to effectively support the electrode assembly, reducing movement and improving the stability of the battery cell. This ratio should also not be too large, for example, less than or equal to 1 / 2, to reduce the space and weight occupied by the supports and increase the energy density of the battery cell.

[0017] In some embodiments, the ratio ranges from [1 / 10, 1 / 5]. Increasing this ratio can effectively improve the structural stability and reliability of the battery cell, while limiting the maximum value of this ratio can increase the energy density of the battery cell.

[0018] In some embodiments, the third bottom walls of the two supports are the same size along the length of the first outer casing wall, so that the supporting forces of the two supports on the electrode assembly along the length of the first outer casing wall are relatively balanced, thereby improving the structural stability inside the battery cell.

[0019] In some embodiments, the tensile strength Rn of the first outer shell wall at a temperature of 500°C satisfies: 100MPa≤Rn≤1200MPa.

[0020] In some embodiments, the material of the first outer casing wall includes steel to increase the structural strength of the first outer casing wall, thereby reducing the thickness of the first outer casing wall.

[0021] In some embodiments, the thickness of the first outer casing wall ranges from [0.5 mm to 1.2 mm]. The thickness of the first outer casing wall is typically greater than or equal to 0.5 mm to meet structural strength requirements, reduce the risk of outer casing wall breakage, and improve the stability of the battery cell. However, the thickness of the first outer casing wall is typically less than or equal to 1.2 mm to increase the energy density of the battery cell.

[0022] In some embodiments, the electrode assembly includes a positive electrode sheet, which includes a positive electrode active material, and the positive electrode active material includes a nickel-containing compound; the nickel-containing compound includes a layered lithium-containing transition metal oxide, wherein the molar amount of nickel in the layered lithium-containing transition metal oxide accounts for more than 50% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide. Increasing the molar amount of nickel in the layered lithium-containing transition metal oxide to more than 50% can effectively improve the energy density and cycle life of the battery cell.

[0023] In some embodiments, the electrode assembly includes a negative electrode sheet, which includes a negative electrode active material, which includes a silicon-based material. The mass percentage (g) of the silicon-based material in the negative electrode active material satisfies 2% ≤ g ≤ 40%. Adding a silicon-based material to the negative electrode active material of the negative electrode sheet can effectively improve the energy density of the battery cell because silicon-based materials can accommodate more metal ions than other elements; for example, the capacity of silicon-based materials is about ten times that of graphite. However, the mass percentage (g) of the silicon-based material should not be set too high to reduce the processing difficulty of the electrode assembly, limit the deformation of the electrode assembly within the battery cell during use, and thus reduce the structural strength requirements and processing difficulty of the battery cell.

[0024] In some embodiments, the first outer casing wall is further provided with two electrode terminals, and the pressure relief mechanism is located between the two electrode terminals along the length direction of the first outer casing wall. On the one hand, placing the electrode terminals and the pressure relief mechanism on the same outer casing wall can improve the integration of the battery cell and facilitate processing; on the other hand, the two electrode terminals are fixed to the first outer casing wall and also relatively fixed to the insulation structure. Therefore, by providing two electrode terminals distributed along the length direction of the first outer casing wall, in the event of thermal runaway of the battery cell, the deformation of the insulation structure and the first outer casing wall along the length direction of the first outer casing wall can be reduced, the deformation of the pressure relief portion located in the middle region of the insulation structure can be reduced, and the stability and reliability of the battery cell can be improved.

[0025] In some embodiments, the pressure relief portion includes two first sidewalls disposed opposite each other along the width direction of the first outer casing wall. Each first sidewall is connected to the first bottom wall by a chamfer, so that the pressure relief portion has a symmetrical structure. This reduces the risk of electrode assemblies being inserted into and damaged at the connection between the two sidewalls and the first bottom wall, thereby causing a short circuit in the battery cell and further improving the reliability of the battery cell and the battery device in which the battery cell is located.

[0026] In some embodiments, the housing includes: a shell having a hollow structure with an opening; and a cover plate for closing the opening, the cover plate including the first housing wall for processing.

[0027] In a second aspect, a battery device is provided, comprising a plurality of battery cells, wherein the battery cells are those described in the first aspect or any embodiment thereof.

[0028] Thirdly, an electrical device is provided, comprising: a battery device including a battery cell as described in the first aspect or any embodiment of the first aspect, the battery device being used to provide electrical energy to the electrical device.

[0029] In some embodiments, the electrical equipment is a vehicle, a ship, or a spacecraft. Attached Figure Description

[0030] Figure 1 is a structural schematic diagram of a vehicle disclosed in an embodiment of this application;

[0031] Figure 2 is an exploded structural diagram of a battery device disclosed in an embodiment of this application;

[0032] Figure 3 is a schematic diagram of the structure of a battery cell disclosed in an embodiment of this application;

[0033] Figure 4 is an exploded structural diagram of a battery cell disclosed in an embodiment of this application;

[0034] Figure 5 is a schematic diagram of an insulation structure disclosed in an embodiment of this application;

[0035] Figure 6 is a schematic diagram of another structure of an insulation structure disclosed in an embodiment of this application;

[0036] Figure 7 is a top view schematic diagram of a battery cell disclosed in an embodiment of this application;

[0037] Figure 8 is a partial cross-sectional schematic diagram of a battery cell disclosed in an embodiment of this application;

[0038] Figure 9 is a partial cross-sectional schematic diagram of an insulation structure disclosed in an embodiment of this application;

[0039] Figure 10 is another partial cross-sectional schematic diagram of an insulation structure disclosed in an embodiment of this application;

[0040] Figure 11 is another partial cross-sectional schematic diagram of a battery cell disclosed in an embodiment of this application;

[0041] Figure 12 is another cross-sectional schematic diagram of a battery cell disclosed in an embodiment of this application;

[0042] Figure 13 is another partial cross-sectional schematic diagram of a battery cell disclosed in an embodiment of this application.

[0043] The accompanying drawings are not drawn to scale. Detailed Implementation

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0049] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0050] The battery apparatus 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 connected in series, parallel, or mixed connections via a busbar.

[0051] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0052] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0053] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0054] 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.

[0055] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0056] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0057] The development of battery technology must consider multiple design factors simultaneously, such as performance parameters like energy density, cycle life, discharge capacity, and charge / discharge rate. Additionally, the reliability and safety of individual battery cells must be considered. When a battery cell experiences thermal runaway, the pressure relief mechanism is activated, causing the internal pressure of the cell to exceed the external pressure, leading to the release of gas. Driven by this gas pressure, the electrode components inside the battery cell are compressed and pushed upwards towards the pressure relief mechanism. Taking a pressure relief mechanism located on a cover plate as an example, an insulating structure is typically installed between the cover plate and the electrode components. This insulating structure usually has a protrusion facing the electrode components at the location of the pressure relief mechanism. The cover plate and insulating structure deform under the influence of gas pressure, and the electrode components are compressed towards the insulating structure. This can potentially cause the edges of the protrusions in the insulating structure to penetrate the interior of the electrode components, leading to a short circuit or even an explosion in the battery cell.

[0058] Therefore, embodiments of this application provide a battery cell, a battery device, and an electrical appliance that can solve the above-mentioned problems. The battery cell of this application includes a casing, an electrode assembly, and an insulating structure. A pressure relief mechanism is provided on a first outer casing wall. The electrode assembly is housed within the casing, and the insulating structure is located between the first outer casing wall and the electrode assembly. The insulating structure includes a body portion and a pressure relief portion corresponding to the pressure relief mechanism. The pressure relief portion protrudes towards the electrode assembly relative to the body portion. The pressure relief portion includes an intersecting first bottom wall and a first side wall. The first bottom wall is perpendicular to the thickness direction of the first outer casing wall, and the first side wall is perpendicular to the width direction of the first outer casing wall. The surfaces of the first bottom wall and the first side wall that are away from the pressure relief mechanism are connected by a chamfer.

[0059] Because the length of the first outer casing wall is greater than its width, the deformation of the first outer casing wall in the width direction is more severe when a battery cell experiences thermal runaway. Similarly, the deformation of the insulation structure in this width direction is also more severe. For example, when a battery cell experiences thermal runaway, under the influence of internal air pressure, the central region of the insulation structure, compared to the edge region, typically bulges outward towards the battery cell along the width direction of the first outer casing wall, causing its cross-section to deform into an arch shape. The chamfer at the intersection of the surface of the first bottom wall away from the pressure relief mechanism and the surface of the first side wall away from the pressure relief mechanism will shift and twist towards the central region. Simultaneously, the electrode assembly will also move towards the first outer casing wall under air pressure. However, because the chamfer is provided between the surfaces of the first bottom wall and the first side wall away from the pressure relief mechanism, this chamfer is smoother than a right-angled edge. This reduces the risk of a short circuit in the battery cell caused by the insertion of the electrode assembly at the connection between the first bottom wall and the first side wall of the pressure relief section, thus reducing the risk of the battery cell exploding and improving the reliability of the battery cell and the battery device containing it.

[0060] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use battery devices.

[0061] Electrical equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, 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.

[0062] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0063] For example, as shown in Figure 1, which is a structural schematic diagram of a vehicle 1 according to an embodiment of this application, vehicle 1 can be a gasoline vehicle, a natural gas vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A motor 40, a controller 30, and a battery device 10 can be installed inside vehicle 1. The controller 30 is used to control the battery device 10 to supply power to the motor 40. For example, the battery device 10 can be installed at the bottom, front, or rear of vehicle 1. The battery device 10 can be used to power vehicle 1. For example, the battery device 10 can serve as the operating power source for vehicle 1, for example, for the electrical system of vehicle 1, such as for the power requirements of vehicle 1's starting, navigation, and operation. In another embodiment of this application, the battery device 10 can not only serve as the operating power source for vehicle 1, but also as the driving power source for vehicle 1, replacing or partially replacing gasoline or natural gas to provide driving power for vehicle 1.

[0064] For example, Figure 2 shows an exploded structural diagram of the battery device 10 according to an embodiment of this application. As shown in Figure 2, the battery device 10 according to this application embodiment may include multiple battery cells 20 to meet different power usage requirements. The shape of the battery cell 20 according to this application embodiment can be set according to actual application. For example, the battery cell 20 can be a cuboid as shown in Figure 2, or it can be a cylinder or other shape different from that shown in Figure 2. This application embodiment is not limited to this.

[0065] It should be understood that, as shown in FIG. 2, the battery device 10 of this embodiment may further include a housing 11, which can be used to accommodate multiple battery cells 20. The housing 11 of this embodiment has a hollow internal structure, and the multiple battery cells 20 are accommodated within the housing 11. The housing 11 may include two parts, referred to herein as a first housing portion 111 and a second housing portion 112, which are fastened together. The shapes of the first housing portion 111 and the second housing portion 112 can be determined according to the shape of the components housed inside, for example, according to the shape of the combination of the multiple battery cells 20 housed inside. At least one of the first housing portion 111 and the second housing portion 112 has an opening. For example, as shown in Figure 2, the first housing portion 111 and the second housing portion 112 can both be hollow cuboids with one open side each. The openings of the first housing portion 111 and the second housing portion 112 are opposite to each other, and the first housing portion 111 and the second housing portion 112 are interlocked to form a housing 11 with a closed cavity, which can be used to accommodate multiple battery cells 20. The multiple battery cells 20 are connected in parallel, series, or mixed and placed inside the housing 11 formed by the interlocking of the first housing portion 111 and the second housing portion 112.

[0066] For example, unlike what is shown in Figure 2, only one of the first housing portion 111 and the second housing portion 112 may be a hollow cuboid with an opening, while the other is plate-shaped to cover the opening. Taking the second housing portion 112 as a hollow cuboid with one opening, and the first housing portion 111 as a plate-shaped example, then the first housing portion 111 covers the opening of the second housing portion 112 to form a housing 11 with a closed chamber, which can be used to accommodate multiple battery cells 20.

[0067] In some embodiments, the battery device 10 may further include other components. For example, the battery device 10 may further include a busbar component, which can be used to realize electrical connections between multiple battery cells 20, such as in parallel, series, or mixed connections. Specifically, the busbar component can realize electrical connections between battery cells 20 by connecting to the electrode terminals 214 of the battery cells 20; or, the busbar component can also realize electrical connections between battery cells 20 by connecting to other components of the battery cells 20. The busbar component can be fixed to corresponding components of the battery cells 20 by welding, for example, by welding to the electrode terminals 214, a sealing structure, or a housing, etc., and the embodiments of this application are not limited thereto.

[0068] Figure 3 shows a structural schematic diagram of the battery cell 20 according to an embodiment of this application. Figure 4 shows an exploded structural schematic diagram of the battery cell according to an embodiment of this application; for example, Figure 4 can be an exploded structural schematic diagram of the battery cell 20 shown in Figure 3. As shown in Figures 3 and 4, the battery cell 20 according to an embodiment of this application includes a housing 21, which is a hollow structure for accommodating the electrode assembly 22. For example, the housing 21 can be formed by enclosing multiple housing walls.

[0069] It should be understood that the shape of the battery cell 20 in this application embodiment can be flexibly set according to actual application. As an example, the battery cell 20 can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries. This application has no particular limitations.

[0070] Correspondingly, the outer shell 21 of the battery cell 20 can be any polyhedral structure, such as a cuboid or a cylinder. For example, the external shape of the battery cell 20 can be the same as or different from the shape of the internal electrode assembly 22. For example, if the electrode assembly 22 is a cylindrical structure, the outer shell 21 of the battery cell 20 can also be a cylindrical structure, or it can be a cuboid structure. As another example, as shown in Figures 3 and 4, if the electrode assembly 22 is a cuboid structure, the outer shell 21 is usually also a cuboid structure, but the embodiments of this application are not limited to this.

[0071] In some embodiments, the outer casing 21 can be a steel casing, an aluminum casing, a plastic casing (such as a polypropylene casing), a composite metal casing (such as a copper-aluminum composite casing 21), or an aluminum-plastic film, etc. In some embodiments, the outer casing 21 can be a sealed structure or a non-sealed structure. As an example, when the outer casing 21 is a non-sealed structure, the outer casing 21 serves to protect the electrode assembly, and a sealing bag is also included between the outer casing 21 and the electrode assembly. The sealing bag is used to encapsulate the electrode assembly and electrolyte. Specifically, the sealing bag can be a bag-shaped insulating component or an aluminum-plastic film. When the outer casing 21 is a sealed structure, it is used to encapsulate components such as the electrode assembly and electrolyte.

[0072] In this embodiment of the application, the outer casing 21 of the battery cell 20 may include a housing 211, which is a hollow structure with an opening 2111. For example, the electrode assembly 22 may be housed inside the housing 211. The outer casing 21 may also include a cover plate 212, which is used to cover the opening 2111 of the housing 211 to isolate the external environment.

[0073] In some embodiments, the number of cover plates 212 is related to the openings 2111 of the housing 211. If the housing 211 is a hollow structure with an opening 2111 at one end, one cover plate 212 can be provided; or, the housing 211 can be a hollow structure with openings 2111 at both ends, so that the internal electrode assembly 22 can enter the housing from either side, providing installation efficiency, and two cover plates 212 can be provided, with the two cover plates 212 respectively covering the openings 2111 at both ends of the housing 211, but the embodiments of this application are not limited to this.

[0074] The shell 211 in this embodiment may be made of one or more materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. The cover plate 212 may also be made of one or more materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. The material of the cover plate 212 may be the same as or different from that of the shell 211; the materials of the different walls of the shell 211 may also be the same or different.

[0075] In this embodiment, the shell 211 and cover plate 212 are shaped to fit together. For example, as shown in Figures 3 and 4, the shell 211 can be an approximate cuboid structure, and the cover plate 212 can be an approximate rectangular plate structure adapted to the shell 211. The cover plate 212 can be any wall of the shell 21. For example, the cover plate 212 can be the wall with the largest area among the multiple walls included in the shell 21, or the wall with the smallest area, or it can be other walls. This embodiment is not limited to this. Alternatively, unlike Figures 3 and 4, the cover plate 212 can also have other structures. For example, the cover plate 212 can also be a groove structure with an opening to cover the opening 2111 of the shell 211. This embodiment is not limited to this.

[0076] For ease of explanation, this application mainly takes the shell 21 as an approximately cuboid as shown in Figures 3 and 4 as an example; the shell 211 is a hollow structure with one end open; correspondingly, by setting a cover plate 212 to cover the opening 2111 of the shell 211, for example, the shell 211 and the cover plate 212 can be sealed by welding to form a closed cavity for placing the electrode assembly 22, thereby improving the sealing reliability.

[0077] In addition, for the rectangular battery cell 20, three reference directions are defined in this embodiment for ease of description. The thickness direction of the battery cell 20 is direction Y, the height direction of the battery cell 20 is direction Z, and the length direction of the battery cell 20 is direction X. The thickness direction Y, the height direction Z, and the length direction X of the battery cell 20 are perpendicular to each other, and the dimension of the battery cell 20 in the thickness direction Y is smaller than the dimension in the length direction X.

[0078] In this embodiment of the application, the electrode assembly 22 is housed within the housing 21. The electrode assembly 22 is a component in the battery cell 20 where an electrochemical reaction occurs. Depending on actual usage requirements, the electrode assembly 22 in the battery cell 20 can be configured as one or more.

[0079] The electrode assembly 22 includes a positive electrode, a negative electrode, and a separator, with the separator positioned between the negative and positive electrodes. During the charging and discharging process of the battery cell 20, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, serves to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0080] The electrode assembly 22 can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0081] In some embodiments, the electrode assembly 22 is a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0082] In some embodiments, the electrode assembly 22 has a stacked structure.

[0083] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0084] As an example, multiple positive electrode sheets can be set, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0085] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0086] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0087] As an example, the separator can be continuously arranged between any adjacent positive or negative electrode plates by folding or rolling.

[0088] In some embodiments, the electrode assembly 22 may be cylindrical, flat, or polygonal in shape.

[0089] For any electrode assembly 22, the electrode assembly 22 may include tabs 222 and electrode body portion 221. Specifically, as shown in Figures 3 and 4, the electrode assembly 22 may include at least two tabs 222, which may include at least one positive tab 222a and at least one negative tab 222b. The positive tab 222a may be formed by stacking the portion of the positive electrode sheet that is not coated with a positive active material layer, while the portion of the positive electrode sheet coated with a positive active material layer may be formed into the electrode body portion 221 by winding or stacking. The negative tab 222b may be formed by stacking the portion of the negative electrode sheet that is not coated with a negative active material layer, while the portion of the negative electrode sheet coated with a negative active material layer may be formed into the electrode body portion 221 by winding or stacking.

[0090] In this embodiment, the plurality of tabs 222 of the electrode assembly 22 can be located on the same or different end faces of the electrode assembly 22. For example, the electrode assembly 22 may include two tabs 222 with opposite polarities. These two tabs 222 may be located on the same end face, or they may be located on different end faces, such as oppositely positioned end faces. This embodiment is not limited to this. For ease of explanation, as shown in Figures 3 and 4, this embodiment mainly uses the example where the two tabs 222 with opposite polarities of the electrode assembly 22 are both located on the same end face of the electrode assembly 22.

[0091] It should be understood that the electrode assembly 22 in this embodiment includes a positive electrode sheet, which includes a positive active material. For example, the positive electrode sheet may be provided with a positive active material that can reversibly extract and insert metal ions. The positive active material coated on the positive electrode sheet can be used to form a positive electrode film layer, which can be disposed on at least one side of the surface of the positive current collector. For example, a positive electrode film layer can be disposed on both sides of the positive current collector perpendicular to its thickness direction, but this embodiment is not limited to this.

[0092] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. An example of a metal material may be one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. An example of a polymer substrate may be one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0093] It should be understood that the positive electrode active material in the embodiments of this application can be flexibly set according to actual applications. For example, the positive electrode active material may include a nickel-containing compound. As an example, the nickel-containing compound includes a layered lithium-containing transition metal oxide, wherein the molar amount of nickel in the layered lithium-containing transition metal oxide accounts for more than 50% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide. Increasing the molar amount of nickel in the layered lithium-containing transition metal oxide to more than 50% can effectively improve the energy density and cycle life of the battery cell 20, but this proportion should not be set too high, otherwise it will increase the processing difficulty of the electrode assembly 22, and thus increase the processing cost of the battery cell 20.

[0094] Furthermore, the molar proportion of nickel in the layered lithium-containing transition metal oxide can be above 70%, or above 80%, or above 90%. This effectively increases the energy density of the battery cell 20 while controlling the processing difficulty of the electrode assembly 22, thereby reducing the processing cost of the battery cell 20.

[0095] In some embodiments, the molar percentage of nickel in the layered lithium-containing transition metal oxide of this application can be set to other values. For example, the molar percentage of nickel in the layered lithium-containing transition metal oxide can be any one of the following values ​​or between any two of the following values: 50%, 53%, 55%, 58%, 60%, 63%, 65%, 68%, 70%, 73%, 75%, 78%, 80%, 83%, 85%, 88%, 90%, 92%, 94%, 96%, and 98%.

[0096] It should be understood that the testing methods for the molar amount of nickel and the total molar amount of transition metal elements in the layered lithium-containing transition metal oxides of this application embodiment can be selected according to actual applications and can be determined using instruments and methods known in the art. For example, the positive electrode active material can be laid and adhered to conductive adhesive to form a sample to be tested with a length × width of 6cm × 1.1cm; the particle morphology can be tested using a scanning electron microscope and energy dispersive spectroscopy (such as ZEISS Sigma 300). The test can refer to JY / T010-1996. To ensure the accuracy of the test results, 20 different regions can be randomly selected in the sample to be tested for scanning, and the content of layered lithium-containing transition metal oxides in each region can be statistically calculated at a certain magnification (e.g., above 1000x). For example, the average value of the test results of the 20 test regions can be taken as the amount of layered lithium-containing transition metal oxides in the positive electrode active material, thereby determining the molar amount of layered lithium-containing transition metal oxides; similarly, the molar amount of nickel in the layered lithium-containing transition metal oxides can also be determined by this method.

[0097] In some embodiments, the layered lithium-containing transition metal oxide may include one or more of lithium cobalt oxide and ternary materials. As an example, the layered lithium-containing transition metal oxide includes LiaNibCocMdOeAf, where 0 < a ≤ 1.2, 0.5 ≤ b < 1, optionally 0.9 ≤ b < 1; 0 < c < 1; 0 < d < 1; 1 ≤ e ≤ 2; 0 ≤ f ≤ 1, M includes, but is not limited to, one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A includes, but is not limited to, one or more of N, F, S, and Cl. The molar proportion b of nickel in the layered lithium-containing transition metal oxide is set to 50% or more, i.e., this proportion b satisfies: 0.5 ≤ b < 1, and further satisfies 0.8 ≤ b < 1, or 0.9 ≤ b < 1, thereby further improving the energy density of the battery cell 20.

[0098] As an example, layered lithium-containing transition metal oxides may include, but are not limited to, LiNi. 0.5 Co 0.2 Mn 0.3 O2 (abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM811), LiNi 0.9Co 0.06 Mn 0.04 O2, LiNi 0.96 Co 0.02 Mn 0.02 O2, LiNi 0.85 Co 0.15 Al 0.05 One or more of O2.

[0099] In some embodiments, the positive electrode film may also include other materials. For example, the positive electrode film may also include a positive electrode conductive agent. This application does not impose any particular limitation on the type of positive electrode conductive agent. As an example, the positive electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0100] In some embodiments, the positive electrode film layer may further include a positive electrode binder. This application does not impose any particular limitation on the type of positive electrode binder. As an example, the positive electrode binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0101] In some embodiments, the positive electrode sheet can be prepared by the following method: the positive electrode film layer is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is typically formed by dispersing positive electrode active materials, positive electrode binders, positive electrode conductive agents, etc., in a solvent and stirring them evenly. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but the embodiments of this application are not limited to these.

[0102] It should be understood that the electrode assembly 22 in this embodiment includes a negative electrode sheet, which includes a negative electrode active material. For example, the negative electrode sheet may include a negative electrode active material capable of reversibly extracting and inserting metal ions. The negative electrode active material coated on the negative electrode sheet can be used to form a negative electrode film layer, which can be disposed on the surface of at least one side of the negative electrode current collector. For example, negative electrode film layers can be disposed on both sides of the negative electrode current collector perpendicular to its thickness direction.

[0103] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, aluminum foil, and aluminum alloy foil. The composite current collector may include a polymer substrate and a metal material layer formed on at least one surface of the polymer substrate. Examples of the metal material include one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of the polymer substrate include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0104] It should be understood that the negative electrode active material in the embodiments of this application can be flexibly configured according to actual applications. Specifically, the negative electrode active material in the embodiments of this application may include silicon-based materials, thereby improving the energy density of the battery. For example, silicon-based materials may include at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, silicon-containing alloys, or silicon-oxygen-carbon composite materials.

[0105] In some embodiments, the silicon-based material may include silicon and one or more of alkali metals and alkaline earth metals. For example, the alkali metal may include Li. For example, the alkaline earth metal may include Mg. For example, the silicon-based material may be a silicon-based material pre-intercalated with alkali metals and / or alkaline earth metals, such as a silicon-based material pre-intercalated with Li and / or Mg.

[0106] It should be understood that the mass percentage g of the silicon-based material in the embodiments of this application can be flexibly set according to actual applications.

[0107] For example, the mass percentage g of the silicon-based material can be set to satisfy 2% ≤ g ≤ 40%. Adding silicon-based material to the negative electrode active material of the negative electrode sheet can effectively improve the energy density of the battery cell 20 because silicon-based material can accommodate more metal ions than other elements; for example, the capacity of silicon-based material is about ten times that of graphite. However, the mass percentage g of the silicon-based material should not be set too high, otherwise it will increase the processing difficulty of the electrode assembly 22 and also increase the deformation of the electrode assembly 22 within the battery cell 20 during use. Especially during the charging process of the battery cell 20, the embedding of metal ions into the silicon-based material of the negative electrode sheet causes the electrode assembly 22 to expand in volume, thereby increasing the pressure of the electrode assembly 22 on the casing 211 of the battery cell 20, and further increasing the processing difficulty of the battery cell 20.

[0108] Furthermore, the mass percentage g of the silicon-based material can be set to satisfy 8% ≤ g ≤ 40%. Appropriately reducing the mass percentage g of the silicon-based material can reduce the processing difficulty of the electrode assembly 22, and also reduce the deformation of the electrode assembly 22 during the charging and discharging of the battery cell 20, that is, reduce the volume expansion of the electrode assembly 22. This reduces the pressure of the electrode assembly 22 on the casing 211 of the battery cell 20, lowers the structural strength requirements of the casing 211, facilitates processing, and reduces costs.

[0109] Furthermore, the mass percentage g of the silicon-based material can be set to satisfy 10% ≤ g ≤ 30%. Reasonably adjusting the mass percentage g of the silicon-based material can effectively increase the energy density of the battery cell 20, reduce the processing difficulty of the electrode assembly 22, and effectively reduce the deformation of the electrode assembly 22 during the charging and discharging process of the battery cell 20, thereby reducing the structural strength requirements of the casing 211.

[0110] In some embodiments, the mass percentage g of the silicon-based material in this application embodiment can be set to other values. For example, the mass percentage g of the silicon-based material can be any one of the following values ​​or between any two of the following values: 5%, 8%, 10%, 13%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, 33%, 35%, 38%, 40%, 43%, 45%, 48%, and 50%.

[0111] It should be understood that the mass percentage g of silicon-based material in the negative electrode active material of this application embodiment represents the ratio of the mass of silicon-based material to the total mass of the negative electrode active material. The test method for the mass percentage g of silicon-based material can be selected according to the actual application and can be tested using methods known in the art.

[0112] In the embodiments of this application, the negative electrode film layer may also include other materials. For example, the negative electrode film layer may also include a negative electrode binder. For example, the negative electrode binder may include one or more of the following: styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). The embodiments of this application are not limited in this regard.

[0113] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. This application does not impose any particular limitation on the type of negative electrode conductive agent. As an example, the negative electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0114] In some embodiments, the negative electrode film layer may also include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0115] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode active material. For example, in some embodiments, the negative electrode sheet may also include a conductive undercoat (e.g., composed of a conductive agent and a binder) sandwiched between the negative electrode current collector and the negative electrode active material and disposed on the surface of the negative electrode current collector; in some embodiments, the negative electrode sheet may also include a protective layer covering the surface of the negative electrode active material.

[0116] In some embodiments, the negative electrode sheet can be prepared by dispersing the negative electrode active material, optional negative electrode binder, optional negative electrode conductive agent, and optional other additives in a solvent and stirring until homogeneous to form a negative electrode slurry; coating the negative electrode slurry onto a negative electrode current collector, and then performing processes such as drying and cold pressing to form the negative electrode sheet. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but the embodiments of this application are not limited to these.

[0117] In this embodiment, the outer casing 21 includes a first outer casing wall 210 with a pressure relief mechanism 213. The first outer casing wall 210 can be any wall of the outer casing 21. The pressure relief mechanism 213 is actuated when the temperature or pressure inside the battery cell 20 reaches a threshold value to release internal gas and temperature from the battery cell 20. For example, the casing 211 includes the first outer casing wall 210, meaning the outer casing wall 210 can be any wall of the casing 211, such as a side wall or bottom wall. Alternatively, the cover plate 212 includes the first outer casing wall 210, and the pressure relief mechanism 213 is provided on the cover plate 212 to facilitate the fabrication of the pressure relief mechanism 213.

[0118] As an example, the pressure relief mechanism 213 is actuated to release internal pressure or temperature when the internal pressure or temperature of the battery cell 20 reaches a predetermined threshold. When the internal pressure or temperature of the battery cell 20 reaches the predetermined threshold, the pressure relief mechanism 213 performs an action or a weak structure provided in the pressure relief mechanism 213 is destroyed, thereby forming an opening or channel for the release of internal pressure or temperature. The threshold design varies depending on design requirements. The threshold may depend on the materials of one or more of the positive electrode, negative electrode, electrolyte, and separator in the battery cell 20.

[0119] As an example, the pressure relief mechanism 213 can be integrally formed with the first outer shell wall 210. As an example, the pressure relief mechanism 213 can also be separately configured and connected to the first outer shell wall 210.

[0120] The term "actuation" as used in this application refers to the pressure relief mechanism 213 being activated or undergoing a certain state, thereby releasing the internal pressure and temperature of the battery cell 20. The actions of the pressure relief mechanism 213 may include, but are not limited to: movement of components within the pressure relief mechanism 213 to form an exhaust channel, rupture, breakage, tearing, or opening of at least a portion of the pressure relief mechanism 213, etc. When the pressure relief mechanism 213 is actuated, the high-temperature, high-pressure substances inside the battery cell 20 are discharged outwards from the actuated portion as exhaust materials. This method enables pressure and temperature relief of the battery cell 20 under controllable pressure or temperature conditions, thereby preventing potentially more serious accidents.

[0121] In some embodiments, when the housing is a non-sealed structure, the pressure relief mechanism 213 can be configured as a through hole for discharging gas inside the battery cell 20.

[0122] The emissions from the battery cell 20 mentioned in this application include, but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of separators, high-temperature and high-pressure gases generated by the reaction, flames, etc.

[0123] In this embodiment, the battery cell 20 further includes an insulating structure 23. Figures 5 and 6 show schematic diagrams of the insulating structure 23 from different angles in this embodiment. Figure 5 mainly shows the side of the insulating structure 23 facing the first outer casing wall 210, and Figure 6 mainly shows the side of the insulating structure 23 facing the electrode assembly 22. Figure 7 shows a top view of the battery cell 20 in this embodiment; Figure 8 shows a partial cross-sectional view of the battery cell 20 in this embodiment, for example, this partial cross-sectional view shows a portion of the cross-section along the A-A' direction as shown in Figure 7.

[0124] Specifically, as shown in Figures 5 to 8, the insulating structure 23 is located between the first outer shell wall 210 and the electrode assembly 22. The insulating structure 23 includes a body portion 231 and a pressure relief portion 232 corresponding to the pressure relief mechanism 213. The pressure relief portion 232 protrudes toward the electrode assembly 22 relative to the body portion 231. The pressure relief portion 232 includes an intersecting first bottom wall 2321 and a first side wall 2322. The first bottom wall 2321 is perpendicular to the thickness direction of the first outer shell wall 210, and the first side wall 2322 is perpendicular to the width direction of the first outer shell wall 210. The surfaces of the first bottom wall 2321 and the first side wall 2322 that are away from the pressure relief mechanism 213 are connected by a chamfer 2323.

[0125] It should be understood that the insulating structure 23 in this embodiment is located between the first housing wall 210 and the electrode assembly 22. The body portion 231 of the insulating structure 23 is attached to the side of the first housing wall 210 facing the electrode assembly 22. The insulating structure 23 can be used to isolate the first housing wall 210 from the electrode assembly 22.

[0126] The insulating structure 23 includes a pressure relief portion 232 corresponding to the pressure relief mechanism 213. The pressure relief portion 232 can be used to isolate the pressure relief mechanism 213 from the electrode assembly 22. The pressure relief portion 232 protrudes toward the electrode assembly 22 relative to the body portion 231. For example, the side of the pressure relief portion 232 facing the first outer casing wall 210 can be recessed from the body portion 231 toward the electrode assembly 22, thereby providing deformation space for the pressure relief mechanism 213 and reducing the risk that the electrode assembly 22 will obstruct the actuation of the pressure relief mechanism 213.

[0127] In some embodiments, the shape of the pressure relief portion 232 can be configured according to the actual application. For example, the shape of the projection of the pressure relief portion 232 onto the first housing wall 210 can be the same as or different from that of the pressure relief mechanism 213.

[0128] In some embodiments, the pressure relief portion 232 may further include a pressure relief hole 2324, so that when the internal pressure or temperature of the battery cell 20 reaches a predetermined threshold, the internal pressure or temperature will be disrupted by the pressure relief hole 2324, thereby causing the pressure relief mechanism 213 to be actuated in a timely manner to release the internal pressure or temperature.

[0129] The pressure relief section 232 includes an intersecting first bottom wall 2321 and a first side wall 2322. The first bottom wall 2321 is perpendicular to the thickness direction of the first outer casing wall 210, and the first side wall 2322 is perpendicular to the width direction of the first outer casing wall 210. The connection between the first bottom wall 2321 and the first side wall 2322 extends along the length direction of the first outer casing wall 210. For example, as shown in Figures 5 to 8, in this embodiment, the thickness direction of the first outer casing wall 210 is taken as the height direction Z of the battery cell 20, and the width direction of the first outer casing wall 210 is taken as the width direction Y of the battery cell 20. The length direction of the first outer casing wall 210 is the length direction X of the battery cell 20. Furthermore, the first bottom wall 2321 is a wall facing the electrode assembly 22, the first side wall 2322 intersects with the first bottom wall 2321, and the connection between the first bottom wall 2321 and the first side wall 2322 extends along the length direction of the first outer casing wall 210.

[0130] As shown in Figures 5 to 8, since the length dimension of the first outer casing wall 210 is greater than its width dimension, the deformation of the first outer casing wall 210 in the width direction is more severe when the battery cell 20 experiences thermal runaway. Similarly, the deformation of the insulating structure 23 in the width direction is also more severe. For example, when the battery cell 20 experiences thermal runaway, due to the influence of internal air pressure, the central region of the insulating structure 23 will typically bulge outwards from the battery cell 20 compared to the edge region along the width direction of the first outer casing wall 210, causing its cross-section perpendicular to the length direction of the first outer casing wall 210 to deform into an arch shape. Taking the first bottom wall 2321 shown in Figure 8 as an example, along the width direction of the first outer shell wall 210, the central area of ​​the first bottom wall 2321 will bulge away from the electrode assembly 22 compared to the edge area, causing the cross section of the first bottom wall 2321 to deform into an arch shape. Then, the chamfer 2323 provided at the intersection of the surface of the first bottom wall 2321 away from the pressure relief mechanism 213 and the surface of the first side wall 2322 away from the pressure relief mechanism 213 will shift and twist towards the central area. At the same time, the electrode assembly 22 will also move towards the insulating structure 23 and the first outer shell wall 210 under the action of air pressure. However, since a chamfer 2323 is provided between the surface of the first bottom wall 2321 away from the pressure relief mechanism 213 and the surface of the first side wall 2322 away from the pressure relief mechanism 213, the chamfer 2323 is smoother than a right angle edge, which can reduce the risk of the chamfer 2323 at the connection between the first bottom wall 2321 and the first side wall 2322 of the pressure relief part 232 inserting into the electrode assembly 22 and damaging the electrode assembly 22, thereby causing a short circuit in the battery cell 20, the risk of the battery cell 20 exploding can be reduced, and the reliability of the battery cell 20 and the battery device 10 in which the battery cell 20 is located can be improved.

[0131] In some embodiments, the pressure relief section 232 includes two first sidewalls 2322 disposed opposite to each other along the width direction of the first outer casing wall 210. For example, as shown in Figures 5 to 8, the first bottom wall 2321 may be connected to the two opposing first sidewalls 2322. The surface of each first sidewall 2322 away from the pressure relief mechanism 213 is connected to the surface of the first bottom wall 2321 away from the pressure relief mechanism 213 by a chamfer 2323, so that the pressure relief section 232 has a symmetrical structure. This reduces the risk of the electrode assembly 22 being inserted into and damaged at the connection between the two sidewalls 2322 and the first bottom wall 2321, which could lead to a short circuit in the battery cell 20. This further improves the reliability of the battery cell 20 and the battery device 10 in which the battery cell 20 is located.

[0132] In some embodiments, the battery cell 20 may further include electrode terminals 214 for electrical connection with the electrode assembly 22 to output electrical energy from the battery cell 20. Specifically, the battery cell 20 may include at least two electrode terminals 214, including at least one positive electrode terminal 214a and at least one negative electrode terminal 214b. Each electrode terminal 214 is used for electrical connection with a corresponding tab 222. For example, each electrode terminal 214 can be electrically connected to a corresponding tab 222 via a connecting member. For example, the positive tab 222a of the electrode assembly 22 can be connected to the positive electrode terminal 214a via a connecting member, and the negative tab 222b of the electrode assembly 22 can be connected to the negative electrode terminal 214b via another connecting member.

[0133] At least two electrode terminals 214 of the battery cell 20 can be disposed on the same wall or different walls of the battery cell 20. For example, the position of the electrode terminals 214 can be set according to the position of the tabs 222 of the electrode assembly 22. For example, as shown in Figures 5 to 8, the embodiments of this application mainly take the battery cell 20 including two electrode terminals 214 as an example, and the two electrode terminals 214 are disposed on the same wall of the outer casing 21 of the battery cell 20.

[0134] In some embodiments, the first outer casing wall 210 is further provided with two electrode terminals 214, and the pressure relief mechanism 213 is located between the two electrode terminals 214 along the length direction of the first outer casing wall 210. On the one hand, by providing the electrode terminals 214 and the pressure relief mechanism 213 on the same outer casing wall, the integration of the battery cell 20 can be improved, which facilitates processing. On the other hand, the two electrode terminals 214 are fixed to the first outer casing wall 210 and also relatively fixed to the insulating structure 23. Therefore, by providing two electrode terminals 214 distributed along the length direction of the first outer casing wall 210, the deformation of the insulating structure 23 and the first outer casing wall 210 along the length direction of the first outer casing wall 210 can be reduced when the battery cell experiences thermal runaway. This reduces the deformation of the pressure relief portion 232 located in the middle region of the insulating structure 23, thereby improving the stability and reliability of the battery cell 20.

[0135] As shown in Figures 5 to 8, the insulating structure 23 includes two electrode lead-out holes 235, so that two electrode terminals 214 can pass through the corresponding electrode lead-out holes 235 to be fixed to the first housing wall 210. The insulating structure 23 can be used to isolate the electrode terminals 214 from the side of the first housing wall 210 facing the electrode assembly 22.

[0136] It should be understood that the configuration of the first outer shell wall 210 in this application embodiment can be flexibly configured according to actual applications.

[0137] In some embodiments, the tensile strength Rn of the first outer casing wall 210 of the outer casing 21 in this application embodiment satisfies the following condition at a temperature of 500°C: 100MPa≤Rn≤1200MPa. When a battery cell 20 experiences thermal runaway during use, the internal temperature of the battery cell 20 increases rapidly and generates a large amount of gas. This is especially true when the positive electrode active material of the positive electrode sheet contains a large amount of nickel-containing compounds, leading to a more violent reaction during thermal runaway. Therefore, increasing the tensile strength Rn of the first outer casing wall 210 at a high temperature of 500°C can improve its deformation capability during thermal runaway of the battery cell 20, making it less prone to rapid damage and explosion, thereby reducing the risk of thermal runaway in adjacent battery cells 20 and improving the reliability of the battery device 10. However, the tensile strength Rn under this high temperature condition should not be too high, otherwise it will increase processing difficulty, such as easily scratching the mold and reducing its service life. Therefore, appropriately reducing the tensile strength Rn can save costs and facilitate processing. For example, the tensile strength Rn can usually be set to satisfy 100MPa≤Rn≤1200MPa.

[0138] It should be understood that the range of tensile strength Rn of the first outer casing wall 210 under high temperature conditions of 500°C in this embodiment can be adjusted according to actual applications. For example, the value of the high-temperature tensile strength Rn can satisfy 100MPa≤Rn≤1200MPa. Another example is that the value of the high-temperature tensile strength Rn can also satisfy 112MPa≤Rn≤720MPa. On the one hand, appropriately increasing the value of the tensile strength Rn can improve the deformation capability of the first outer casing wall 210 when the battery cell 20 experiences thermal runaway, making the first outer casing wall 210 less prone to rapid damage and explosion, thereby reducing the risk of thermal runaway in adjacent battery cells 20 and improving the reliability of the battery device 10. Simultaneously, controlling the tensile strength Rn of the first outer casing wall 210 under high-temperature conditions to prevent excessively high tensile strength reduces processing difficulty, thereby saving costs and facilitating processing.

[0139] Furthermore, the high-temperature tensile strength Rn can be set to satisfy 152MPa≤Rn≤480MPa. This can improve the deformation capability of the first outer casing 210 when the battery cell 20 experiences thermal runaway, increase the structural strength of the first outer casing 210, and make the first outer casing 210 less prone to rapid damage and explosion. This reduces the risk of thermal runaway in adjacent battery cells 20, thereby improving the reliability of the battery device 10. It can also reduce processing difficulty and save costs.

[0140] In some embodiments, the high-temperature tensile strength Rn of this application can also be set to other values. For example, the high-temperature tensile strength Rn can be any one of the following values ​​or between any two of the following values: 100MPa, 112MPa, 130MPa, 150MPa, 152MPa, 168MPa, 180MPa, 200MPa, 228MPa, 250MPa, 280MPa, 300MPa, 320MPa, 350MPa, 380MPa, 400MPa, 430MPa, 450MPa, 480MPa, 500MPa. Pa, 530MPa, 550MPa, 580MPa, 600MPa, 630MPa, 650MPa, 680MPa, 700MPa, 720MPa, 750MPa, 780MPa, 800MPa, 8 30MPa, 850MPa, 880MPa, 900MPa, 930MPa, 950MPa, 980MPa, 1000MPa, 1050MPa, 1100MPa, 1150MPa and 1200MPa.

[0141] It should be understood that the tensile strength in this application embodiment refers to the maximum stress value that the material can withstand before breaking. The test method for the tensile strength Rn of the first outer shell wall 210 in this application embodiment under high temperature conditions of 500°C can be selected according to actual application. For example, the national standard GB / T 228.1-2010 can be used to test the tensile strength Rn under high temperature conditions of 500°C.

[0142] It should be understood that in this embodiment of the application, the tensile strength of the first outer shell wall 210 under 500°C conditions is set as Rn. The 500°C condition means that the test temperature of the tensile strength Rn is 500°C or approximately 500°C. For example, the specific test temperature can be 500°C ± 2°C or 500°C ± 5°C.

[0143] In some embodiments, the specific material of the first outer shell wall 210 can be flexibly set according to the actual application. For example, the material of the first outer shell wall 210 includes steel to improve the structural strength of the first outer shell wall 210. For example, this can make the first outer shell wall 210 easier to meet the above-mentioned design requirements, while also reducing the thickness of the first outer shell wall 210.

[0144] It should be understood that the above-described design of the tensile strength and material of the first outer shell wall 210 also applies to the other walls of the outer shell 21. For example, the tensile strength Rn of each wall of the outer shell 21 at a temperature of 500°C can be set to satisfy: 100MPa≤Rn≤1200MPa, and / or, the materials of each wall of the outer shell 21 can be the same to improve the overall structural strength of the outer shell 21 and facilitate processing, for example, to facilitate welding between the shell 211 and the cover plate 212 made of the same material, thereby improving processing efficiency.

[0145] In some embodiments, the thickness L1 of the first outer shell wall 210 can be flexibly set according to the actual application. For example, the thickness L1 of the first outer shell wall 210 can be set according to the material of the first outer shell wall 210 so that the structural strength of the first outer shell wall 210 meets the design requirements. For example, if the material of the first outer shell wall 210 includes steel, the thickness L1 of the first outer shell wall 210 can be reduced. As another example, considering that the first outer shell wall 210 is provided with a pressure relief mechanism 213, or may also be provided with an electrode terminal 214, the thickness of the first outer shell wall 210 is usually greater than the thickness of other outer shell walls. For example, taking the first outer shell wall 210 as a cover plate 212, the thickness of the cover plate 212 is usually greater than the thickness of the wall of the housing 211.

[0146] In some embodiments, the thickness L1 of the first outer casing 210 ranges from [0.5 mm to 1.2 mm]. The thickness L1 of the first outer casing 210 is typically greater than or equal to 0.5 mm to meet structural strength requirements, reduce the risk of the outer casing 210 cracking, and improve the stability of the battery cell 20. However, the thickness L1 of the first outer casing 210 is typically less than or equal to 1.2 mm to increase the energy density of the battery cell 20.

[0147] In some embodiments, the thickness L1 of the first outer casing 210 can also be [0.6 mm, 1 mm]. Appropriately increasing the thickness L1 of the first outer casing 210 can improve the structural strength of the first outer casing 210; or, the structural strength of the first outer casing 210 can be improved by selecting a suitable material and reducing the thickness L1 of the first outer casing 210, so as to improve the energy density of the battery cell 20.

[0148] In some embodiments, the thickness L1 of the first outer shell wall 210 may be any of the following values ​​or between any two of the following values: 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.05mm, 1.1mm, 1.15mm, and 1.2mm.

[0149] It should be understood that the thickness L1 of the first outer casing wall 210 in this embodiment can refer to the average thickness or minimum thickness of at least a portion of the first outer casing wall 210. For example, the thickness L1 of the first outer casing wall 210 can refer to the thickness of a relatively flat area of ​​the first outer casing wall 210. For example, when the first outer casing wall 210 is provided with a pressure relief mechanism 213, the thickness L1 of the first outer casing wall 210 refers to the thickness of the area of ​​the first outer casing wall 210 excluding the pressure relief mechanism 213. Similarly, when the first outer casing wall 210 is provided with an electrode terminal 214, the thickness L1 of the first outer casing wall 210 refers to the thickness of the area of ​​the first outer casing wall 210 excluding the electrode terminal 214. When the first outer casing wall 210 is provided with a liquid injection structure 215, the thickness L1 of the first outer casing wall 210 refers to the thickness of the area of ​​the first outer casing wall 210 excluding the liquid injection structure 215.

[0150] Because the thickness L1 of the first outer casing 210 is relatively thin, the deformation of the first outer casing 210 is relatively large when the battery cell 20 experiences thermal runaway, especially in the width direction of the first outer casing 210, which corresponds to a larger deformation in the width direction of the insulating structure 23. Therefore, by providing a chamfer 2323 between the surface of the first bottom wall 2321 away from the pressure relief mechanism 213 and the surface of the first side wall 2322 away from the pressure relief mechanism 213, the risk of the chamfer 2323 at the connection between the first bottom wall 2321 and the first side wall 2322 of the pressure relief part 232 being inserted into the electrode assembly 22 and damaging the electrode assembly 22, thereby causing a short circuit in the battery cell 20, can be effectively reduced. This also reduces the risk of the battery cell 20 exploding and improves the reliability of the battery cell 20 and the battery device 10 in which the battery cell 20 is located.

[0151] The chamfer 2323 of the present application embodiment will now be described with reference to the accompanying drawings. In some embodiments, the chamfer 2323 of the present application embodiment may include a rounded corner or a beveled corner.

[0152] Figure 9 shows a partial cross-sectional view of the insulating structure 23 according to an embodiment of this application. For example, Figure 9 can be a possible cross-sectional view of the chamfer 2323 of the insulating structure 23, which is perpendicular to the length direction X of the battery cell 20. For example, Figure 9 can be a possible implementation of the chamfer 2323 in Figure 8.

[0153] In some embodiments, as shown in FIG9, the chamfer 2323 is a rounded corner, that is, the connection between the first bottom wall 2321 and the first side wall 2322 is arc-shaped. The side of the pressure relief part 232 facing the electrode assembly 22 is more rounded. In the event of thermal runaway of the battery cell 20, the risk of the electrode assembly 22 being inserted into this part of the area and damaged is reduced, thereby reducing the risk of short circuit of the battery cell 20, which can also reduce the risk of explosion of the battery cell 20 and improve the reliability of the battery cell 20 and the battery device 10 in which the battery cell 20 is located.

[0154] It should be understood that the size of the fillet can be set according to the actual application. For example, the radius R of the fillet can range from 1mm to 40mm. Setting the radius R of the fillet to be greater than or equal to 1mm makes this part of the area smoother, reducing the risk of inserting this part of the area into the electrode assembly 22 and damaging the electrode assembly 22, thereby improving the reliability of the battery cell 20 and the battery device 10 in which the battery cell 20 is located. However, considering the limited space between the insulation structure and the electrode assembly 22, the radius R of the fillet should not be too large, for example, usually less than or equal to 40mm, in order to reduce the space occupied by the pressure relief part 232 and increase the energy density of the battery cell 20.

[0155] In some embodiments, the radius R of the fillet can also be [1.5mm, 20mm]. Appropriately increasing the radius R of the fillet can further reduce the risk of inserting the electrode assembly 22 into this area and damaging the electrode assembly 22, thereby improving the reliability of the battery cell 20 and the battery device 10 in which the battery cell 20 is located. At the same time, limiting the radius R of the fillet to not be too large can also improve the energy density of the battery cell 20.

[0156] Furthermore, the radius R of the rounded corner is in the range of [2mm, 10mm]. This can reduce the risk of inserting the electrode assembly 22 into this area and damaging the electrode assembly 22, thereby causing a short circuit in the battery cell 20. It can also reduce the space occupied by the pressure relief part 232, so as to balance the relationship between the reliability and energy density of the battery cell 20.

[0157] In some embodiments, the radius R of the fillet can also be any of the following values ​​or between any two of the following values: 1mm, 1.5mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 12mm, 14mm, 15mm, 16mm, 18mm, 20mm, 23mm, 25mm, 28mm, 30mm, 33mm, 35mm, 38mm, and 40mm.

[0158] Figure 10 shows another partial cross-sectional schematic diagram of the insulation structure according to an embodiment of the present application. For example, Figure 10 can be another possible cross-sectional schematic diagram of the chamfer 2323 of the insulation structure 23, which is perpendicular to the length direction X of the battery cell 20. For example, instead of Figure 9, Figure 10 can be another possible implementation of the chamfer 2323 in Figure 8.

[0159] In some embodiments, as shown in FIG10, the chamfer 2323 can also be an angled bevel for ease of processing. In the event of thermal runaway of the battery cell 20, when the first bottom wall 2321 deforms, the angled bevel may shift, and the beveled surface of the angled bends toward the electrode assembly 22, thereby reducing the risk of inserting into and damaging the electrode assembly 22 in that area. This reduces the risk of short circuit in the battery cell 20, and also reduces the risk of explosion of the battery cell 20, thus improving the reliability of the battery cell 20 and the battery device 10 in which the battery cell 20 is located.

[0160] It should be understood that the size of the bevel angle can be set according to the actual application. For example, the angle between the bevel angle and the first bottom wall 2321 can be set according to the actual application. In some embodiments, the plane of the surface of the first bottom wall 2321 facing the electrode assembly 22 intersects the plane of the surface of the first side wall 2322 facing the interior of the battery cell 20 and has an intersection line. The distance from the intersection line to the slope of the bevel angle is D, and the range of values ​​for the distance D can be set according to the actual application.

[0161] For example, the distance D is typically greater than or equal to 0.3 mm so that the angle can effectively reduce the risk of inserting the electrode assembly 22 into this area and damaging the electrode assembly 22, thereby improving the reliability of the battery cell 20 and the battery device 10 in which the battery cell 20 is located. However, the distance D should not be too large, so as to reduce the space occupied by the pressure relief section 232 and increase the energy density of the battery cell 20.

[0162] In some embodiments, the first bottom wall 2321 abuts against the end face of the electrode assembly 22 facing the first outer casing wall 210, so as to support the electrode assembly 22 through the pressure relief portion 232 and improve the internal structural stability of the battery cell 20; and, when the battery cell 20 experiences thermal runaway, it can reduce the displacement of the electrode assembly 22 under the action of internal air pressure, so as to improve the stability and reliability of the battery cell 20.

[0163] Figure 11 shows another partial cross-sectional schematic diagram of the battery cell 20 according to an embodiment of the present application. For example, this partial cross-sectional schematic diagram shows a portion of the cross-section along the B-B' direction as shown in Figure 7.

[0164] In this embodiment of the application, the first outer shell wall 210 is provided with a liquid injection structure 215, and the insulating structure 23 further includes a liquid injection part 233 corresponding to the liquid injection structure 215. The liquid injection part 233 protrudes toward the electrode assembly 22 relative to the body part 231. The liquid injection part 233 can be used to protect the liquid injection structure 215 and improve the stability of the liquid injection structure 215.

[0165] In some embodiments, the electrolyte injection structure 215 may include an injection hole disposed on the first outer casing wall 210 and a sealing structure for sealing the injection hole. Specifically, the electrolyte injection section 233 may include a through hole 2332, so that when electrolyte is injected into the battery cell 20 through the injection hole of the first outer casing wall 210, the electrolyte can flow into the interior of the battery cell 20 sequentially through the injection hole and the through hole 2332 on the electrolyte injection section 233. After the electrolyte injection is completed, the sealing structure can be used to close the injection hole, thereby improving the sealing performance of the battery cell 20. The position of the through hole 2332 can be flexibly set according to the actual application to improve the electrolyte injection efficiency. For example, the through hole 2332 may be disposed on the side wall of the electrolyte injection section 233 to disperse the electrolyte and improve wettability.

[0166] It should be understood that the dimensions of the injection section 233 in this embodiment can be set according to actual applications. For example, the dimensions of the injection section 233 can be set according to the dimensions of the pressure relief section 232.

[0167] In some embodiments, the liquid injection portion 233 includes a second bottom wall 2331, which is perpendicular to the thickness direction of the first outer casing wall 210. The second bottom wall 2331 is farther away from the electrode assembly 22 than the first bottom wall 2321. Specifically, the second bottom wall 2331 being farther away from the electrode assembly 22 than the first bottom wall 2321 means that, along the thickness direction of the first outer casing wall 210, the distance between the second bottom wall 2331 and the end face of the electrode assembly 22 facing the first outer casing wall 210 is greater than the distance between the first bottom wall 2321 and the end face of the electrode assembly 22 facing the first outer casing wall 210. Thus, with the pressure relief portion 232 blocking it, the risk of the liquid injection portion 233 inserting into the electrode assembly 22 can be reduced, thereby reducing the risk of a short circuit in the battery cell 20, which in turn reduces the risk of the battery cell 20 exploding, improving the reliability of the battery cell 20 and the battery device 10 in which it is located.

[0168] For example, as shown in Figures 8 and 11, taking the first bottom wall 2321 abutting against the end face of the electrode assembly 22 facing the first outer shell wall 210 as an example, the second bottom wall 2331 being farther away from the electrode assembly 22 than the first bottom wall 2321 means that, along the thickness direction of the first outer shell wall 210, the distance L2 between the second bottom wall 2331 and the end face of the electrode assembly 22 facing the first outer shell wall 210 is greater than zero, so as to reduce the risk of the liquid injection part 233 being inserted into the electrode assembly 22.

[0169] It should be understood that the height difference between the second bottom wall 2331 and the first bottom wall 2321 along the thickness direction of the first outer shell wall 210 can be set according to the actual application. In this embodiment of the application, taking the first bottom wall 2321 abutting against the end face of the electrode assembly 22 facing the first outer shell wall 210 as an example, as shown in FIG11, the height difference between the second bottom wall 2331 and the first bottom wall 2321 is L2.

[0170] In some embodiments, the height difference L2 between the second bottom wall 2331 and the first bottom wall 2321 along the thickness direction of the first outer casing wall 210 ranges from 0.2 mm to 8 mm. By setting the height difference L2 to be greater than or equal to 0.2 mm, the risk of the liquid injection part 233 being inserted into the electrode assembly 22 can be reduced, thereby reducing the risk of short circuit in the battery cell 20, which in turn reduces the risk of explosion in the battery cell 20, and improves the reliability of the battery cell 20 and the battery device 10 in which the battery cell 20 is located. However, the height difference L2 should not be too large. For example, it can be set to be less than or equal to 8 mm. On the one hand, this ensures that the distance between the second bottom wall 2331 of the liquid injection part 233 and the first outer casing wall 210 along the thickness direction of the first outer casing wall 210 is not too small, so as to protect the liquid injection structure 215 and improve the liquid injection efficiency. On the other hand, it can improve the utilization rate of the internal space of the battery cell 20, thereby improving the energy density of the battery cell 20.

[0171] In some embodiments, the height difference L2 between the second bottom wall 2331 and the first bottom wall 2321 along the thickness direction of the first outer casing wall 210 can also range from [0.5 mm to 7 mm]. Appropriately increasing this height difference L2 can further reduce the risk of the liquid injection portion 233 being inserted into the electrode assembly 22, and improve the reliability of the battery cell 20 and the battery device 10 in which the battery cell 20 is located. At the same time, the height difference L2 should not be too large in order to improve the liquid injection efficiency and the internal space utilization of the battery cell 20.

[0172] Furthermore, along the thickness direction of the first outer casing wall 210, the height difference L2 between the second bottom wall 2331 and the first bottom wall 2321 ranges from [1mm to 5mm]. This effectively reduces the risk of inserting the liquid injection section 233 into the electrode assembly 22, while also improving the liquid injection efficiency and the utilization rate of the internal space of the battery cell 20.

[0173] In some embodiments, along the thickness direction of the first outer shell wall 210, the height difference L2 between the second bottom wall 2331 and the first bottom wall 2321 can be any of the following values ​​or between any two of the following values: 0.2mm, 0.5mm, 0.8mm, 1mm, 1.3mm, 1.5mm, 1.8mm, 2mm, 2.3mm, 2.5mm, 2.8mm, 3mm, 3.3mm, 3.5mm, 3.8mm, 4mm, 4.3mm, 4.5mm, 4.8mm, 5mm, 5.3mm, 5.5mm, 5.8mm, 6mm, 6.3mm, 6.5mm, 6.8mm, 7mm, 7.3mm, 7.5mm, 7.8mm, and 8mm.

[0174] Figure 12 shows another cross-sectional view of the battery cell 20 according to an embodiment of the present application. For example, this cross-sectional view shows a cross-section along the C-C' direction as shown in Figure 7. Figure 13 shows another partial cross-sectional view of the battery cell 20 according to an embodiment of the present application. For example, Figure 13 can be an enlarged view of region E in Figure 12.

[0175] In this embodiment, the insulating structure 23 further includes two support portions 234. Along the length of the first outer casing wall 210, a pressure relief portion 232 is located between the two support portions 234, and the two support portions 234 protrude towards the electrode assembly 22 relative to the body portion 231. Along the length of the first outer casing wall 210, the two support portions 234 provided on both sides of the pressure relief portion 232 of the insulating structure 23 can be used to support the electrode assembly 22, reducing the movement of the electrode assembly 22 towards the first outer casing wall 210 and improving the structural stability of the battery cell 20. Especially in the event of thermal runaway in the battery cell 20, the two support portions 234 can be used to support the electrode assembly, reducing the movement of the electrode assembly 22 towards the first outer casing wall 210 under air pressure, thereby reducing the risk of the pressure relief portion 232 inserting into and damaging the electrode assembly 22, thus reducing the risk of a short circuit in the battery cell 20, and consequently reducing the risk of an explosion in the battery cell 20, improving the reliability of the battery cell 20 and the battery device 10 in which it is located.

[0176] In some embodiments, the specific positions of the two support portions 234 can be set according to the actual application. For example, the two support portions 234 are respectively located at both ends of the insulating structure 23 along the length direction of the first outer shell wall 210, so as to facilitate processing and effectively support the electrode assembly 22, further improving the stability of the electrode assembly 22.

[0177] In some embodiments, each of the two support portions 234 includes a third bottom wall 2341, which is perpendicular to the thickness direction of the first outer casing wall 210 and abuts against the end face of the electrode assembly 22 facing the first outer casing wall 210. The third bottom wall 2341, positioned facing the electrode assembly 22, effectively supports the electrode assembly 22, improving the internal structural stability of the battery cell 20. Furthermore, in the event of thermal runaway in the battery cell 20, it reduces the displacement of the electrode assembly 22 under internal pressure, thereby improving the stability and reliability of the battery cell 20.

[0178] It should be understood that the dimensions of the support portion 234 in this embodiment can be set according to actual application. For example, the dimensions of the two support portions 234 can be different to improve the design flexibility of the insulation structure 23. Alternatively, at least some of the dimensions of the two support portions 234 can be the same to facilitate processing and to balance the support force in different areas of the electrode assembly 22, thereby improving the stability of the electrode assembly 22.

[0179] In some embodiments, the third bottom walls 2341 of the two support portions 234 have the same dimensions along the length direction of the first outer shell wall 210. As shown in Figures 12 and 13, taking the length direction of the first outer shell wall 210 as the length direction X of the battery cell 20 as an example, the two support portions 234 can support the electrode assembly 22 through the third bottom walls 2341. Therefore, by setting the third bottom walls 2341 of the two support portions 234 to have the same dimensions along the length direction of the first outer shell wall 210, the supporting force of the two support portions 234 on the electrode assembly 22 along the length direction of the first outer shell wall 210 is relatively balanced, thereby improving the structural stability inside the battery cell 20. For ease of explanation, this embodiment uses the example where the length of the third bottom walls 2341 of the two support portions 234 is equal to L4 along the length direction of the first outer shell wall 210, but this embodiment is not limited to this.

[0180] In some embodiments, the dimensions of the two support portions 234 can be set according to the dimensions of the electrode assembly 22 to improve structural stability.

[0181] In some embodiments, along the length direction of the first outer casing wall 210, the ratio of the total length 2*L4 of the third bottom wall 234 of the two support portions 234 to the total length L3 of the electrode assembly 22 ranges from [1 / 20, 1 / 2]. This ratio is greater than or equal to 1 / 20, allowing the two support portions 234 to effectively support the electrode assembly 22, reducing movement of the electrode assembly 22 and improving the stability of the battery cell 20. This ratio should also not be too large, for example, less than or equal to 1 / 2, to reduce the space and weight occupied by the support portion 234 and increase the energy density of the battery cell 20.

[0182] In some embodiments, along the length direction of the first outer casing wall 210, the ratio of the total length 2*L4 of the third bottom wall 2341 of the two support portions 234 to the total length L3 of the electrode assembly 22 can also satisfy [1 / 15, 1 / 4]. Increasing this high ratio can improve the supporting effect of the two support portions 234 on the electrode assembly 22, further improving the structural stability of the battery cell 20; at the same time, limiting this ratio should not be too large, which can further improve the energy density of the battery cell 20.

[0183] Furthermore, along the length direction of the first outer casing wall 210, the ratio of the total length 2*L4 of the third bottom wall 234 of the two support portions 234 to the total length L3 of the electrode assembly 22 ranges from [1 / 10, 1 / 5]. Increasing this ratio can effectively improve the structural stability and reliability of the battery cell 20, while limiting the maximum value of this ratio can increase the energy density of the battery cell 20.

[0184] In some embodiments, along the length direction of the first outer shell wall 210, the ratio of the total length 2*L4 of the third bottom wall 2341 of the two support portions 234 to the total length L3 of the electrode assembly 22 can also be any of the following values ​​or be between any two of the following values: 1 / 20, 1 / 18, 1 / 15, 1 / 12, 1 / 10, 1 / 8, 1 / 6, 1 / 5, 1 / 4, 1 / 3, 2 / 5, and 1 / 2.

[0185] In some embodiments, the structure of the support portion 234 can be configured according to the actual application. For example, the support portion 234 may include an exhaust region 2342, which can be used for venting, especially when the battery cell 20 experiences thermal runaway, some gas can be discharged through the exhaust region 2342; in addition, the weight of the insulation structure 23 can be reduced by providing the exhaust region 2342.

[0186] In some embodiments, the exhaust region 2342 of this application may include a through-hole structure or a notch region, but this application is not limited thereto.

[0187] According to some embodiments of this application, this application also provides a battery device 10, including a battery cell 20 as described in any of the above embodiments.

[0188] According to some embodiments of this application, this application also provides an electrical device including the battery device 10 described in any of the above embodiments, and the battery device 10 is used to provide electrical energy to the electrical device.

[0189] The electrical equipment can be any of the aforementioned devices or systems that utilize battery devices.

[0190] According to some embodiments of this application, referring to Figures 5 to 13, this application provides a battery cell, including: a housing 21, the housing 21 including a first housing wall 210 provided with a pressure relief mechanism 213; an electrode assembly 22, housed within the housing 21; and an insulating structure 23 located between the first housing wall 210 and the electrode assembly 22. The insulating structure 23 includes a body portion 231 and a pressure relief portion 232 corresponding to the pressure relief mechanism 213. The pressure relief portion 232 protrudes relative to the body portion 231 toward the electrode assembly 22. The pressure relief portion 232 includes an intersecting first bottom wall 2321 and a first side wall 2322. The first bottom wall 2321 is perpendicular to the thickness direction of the first housing wall 210, and the first side wall 2322 is perpendicular to the width direction of the first housing wall 210. The surfaces of the first bottom wall 2321 and the first side wall 2322 that are away from the pressure relief mechanism 213 are connected by a chamfer 2323. The chamfer 2323 is a rounded corner. The radius of the fillet is in the range of [1mm, 40mm]; or, the radius of the fillet is in the range of [2mm, 10mm]. The first bottom wall 2321 abuts against the end face of the electrode assembly 22 facing the first outer shell wall 210.

[0191] The first outer shell wall 210 is provided with a liquid injection structure 215. The insulating structure 23 also includes a liquid injection part 233 corresponding to the liquid injection structure 215. The liquid injection part 233 protrudes toward the electrode assembly 22 relative to the body part 231. The liquid injection part 233 includes a second bottom wall 2331, which is perpendicular to the thickness direction of the first outer shell wall 210. The second bottom wall 2331 is farther away from the electrode assembly 22 than the first bottom wall 2321. Along the thickness direction of the first outer shell wall 210, the height difference between the second bottom wall 2331 and the first bottom wall 2321 ranges from [0.2mm, 8mm] to [1mm, 5mm].

[0192] The insulating structure 23 also includes two support portions 234. Along the length direction of the first outer shell wall 210, a pressure relief portion 232 is located between the two support portions 234. The two support portions 234 protrude toward the electrode assembly 22 relative to the body portion 231. The two support portions 234 are respectively located at both ends of the insulating structure 23 along the length direction of the first outer shell wall 210. Each of the two support portions 234 includes a third bottom wall 2341, which is perpendicular to the thickness direction of the first outer shell wall 210 and abuts against the end face of the electrode assembly 22 facing the first outer shell wall 210. Along the length direction of the first outer shell wall 210, the ratio of the total length of the third bottom walls 2341 of the two support portions 234 to the total length of the electrode assembly 22 ranges from [1 / 20, 1 / 2] or [1 / 10, 1 / 5].

[0193] The outer casing 21 includes: a shell 211, a hollow structure having an opening 2111; and a cover plate 212 for covering the opening 2111, the cover plate 212 including a first outer casing wall 210. The tensile strength Rn of the first outer casing wall 210 at a temperature of 500℃ satisfies: 100MPa≤Rn≤1200MPa. The material of the first outer casing wall 210 includes steel. The thickness of the first outer casing wall 210 ranges from [0.5mm, 1.2mm].

[0194] The electrode assembly includes a positive electrode sheet, which includes a positive electrode active material. The positive electrode active material includes a nickel-containing compound; the nickel-containing compound includes a layered lithium-containing transition metal oxide, wherein the molar amount of nickel in the layered lithium-containing transition metal oxide accounts for more than 50% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide. The electrode assembly also includes a negative electrode sheet, which includes a negative electrode active material. The negative electrode active material includes a silicon-based material, wherein the mass percentage (g) of the silicon-based material in the negative electrode active material satisfies 2% ≤ g ≤ 40%.

[0195] 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.

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