Battery cell, battery device, and electric device

Abstract

Embodiments of the present application disclose a battery monomer, a battery device and an electric equipment. The battery monomer comprises an electrode assembly, the electrode assembly comprises a positive electrode sheet and a negative electrode sheet, the negative electrode sheet comprises a negative electrode current collector, the negative electrode current collector comprises a negative electrode body and a negative electrode tab, a first surface of the negative electrode body comprises a middle region and two first edge regions; along a first direction, the middle region is located between the two first edge regions, and the negative electrode tab extends from the first edge region of the negative electrode body, the middle region has a metal deposition layer, and at least one of the two first edge regions is provided with a first insulation structure. The battery monomer, the battery device and the electric equipment provided by the embodiments of the present application can improve the performance and structural stability of the battery monomer.

Description

Technical Field

[0001] This application relates to the field of batteries, and more specifically, to a battery cell, a battery device, and an electrical appliance. Background Technology

[0002] Energy conservation and emission reduction are key to the sustainable development of the automotive industry, and electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of this sustainable development. For electric vehicles, battery technology is a crucial factor in their development.

[0003] In the development of battery technology, while increasing the energy density of batteries, ensuring the structural stability and reliability of batteries is also an issue that cannot be ignored. Utility Model Content

[0004] This application provides a battery cell, a battery device, and an electrical appliance, which can improve the performance and structural stability of the battery cell.

[0005] In a first aspect, a battery cell is provided, the battery cell including an electrode assembly, the electrode assembly including a positive electrode and a negative electrode, the negative electrode including a negative current collector, the negative current collector including a negative electrode body and a negative electrode tab, the negative electrode body including at least one first surface, the first surface including a central region and two first edge regions; along a first direction, the central region is located between the two first edge regions, and the negative electrode tab extends from the first edge regions of the negative electrode body, the central region having a metal deposition layer, and at least one of the two first edge regions being provided with a first insulating structure.

[0006] Therefore, in the battery cell of this application embodiment, by providing a first insulating structure in at least one of the two first edge regions of the negative electrode sheet, the metal will be far away from the first edge region during deposition, and the metal deposition layer will preferentially be formed in the middle region. This reduces the accumulation of metal in the first edge region of the negative electrode sheet where the first insulating structure is provided. The first insulating structure can also reduce the overflow of metal from the first edge region where it is located, thereby reducing the overlap between the positive and negative electrodes caused by the overflow of overflowing metal. In other words, it can reduce the risk of internal short circuit in the battery cell after formation, improve the first formation efficiency, improve the cycle life of the battery cell, and improve the reliability of the battery cell.

[0007] In some embodiments, the two first edge regions are respectively provided with a first insulating structure, so that when metal is deposited, a metal deposition layer is preferentially formed in the middle region, while the first edge regions far from the sides can jointly restrict metal overflow from both sides, further reducing the risk of overlap between the positive and negative electrode sheets caused by metal overflow, so as to effectively improve the reliability of the battery cell.

[0008] In some embodiments, the thickness of the first insulating structure is greater than the thickness of the metal deposition layer, which is the same as the thickness of the metal deposition layer when the battery cell is fully charged. By providing a thicker first insulating structure, metal can be prevented from overflowing from the first edge region, thereby effectively reducing the overlap between the positive and negative electrodes caused by overflowing metal. This can reduce the risk of internal short circuits in the battery cell after formation, improve the first formation efficiency, thereby improving the performance and structural stability of the battery cell, and also increasing the cycle life of the battery cell.

[0009] In some embodiments, the difference between the thickness of the first insulating structure and the thickness of the metal deposition layer ranges from 0 μm to 10 μm. On the one hand, this can limit the volume and weight of the electrode assembly to improve the energy density of the battery cell. On the other hand, if the difference is too large, it will result in an excessively thick first insulating structure, affecting the deposition effect of the metal deposition layer, leading to a deterioration of the deposition morphology, and thus affecting the performance of the electrode assembly.

[0010] In some embodiments, the width of the first insulating structure along the first direction ranges from [0.1 mm to 3 mm]. Setting the width of the first insulating structure to be greater than or equal to 0.1 mm enables the first insulating structure to effectively prevent metal from overflowing from the first edge region where the first insulating structure is located, thereby reducing the overlap between the positive and negative electrode sheets caused by overflowing metal; setting the width of the first insulating structure to be less than or equal to 3 mm limits the area of ​​the first surface of the negative electrode sheet occupied by the first insulating structure, thereby improving the energy density of the battery cell.

[0011] In some embodiments, the areal density of the positive electrode sheet ranges from [400g / 1540.25mm²]. 2 1500g / 1540.25mm 2 The thickness of the metal deposition layer ranges from 20 μm to 90 μm, and the thickness of the first insulating structure ranges from 25 μm to 95 μm. The areal density of the positive electrode sheet is limited to 400 g / 1540.25 mm². 2 This means that the coating mass of positive electrode active material per unit area of ​​the positive electrode sheet is relatively large. This can effectively improve the energy density of the battery cell, facilitate uniform coating, reduce processing difficulty, improve production yield, and thus improve the processing efficiency of the battery cell. Additionally, the areal density of the positive electrode sheet on one side is greater than or equal to 400g / 1540.25mm². 2In this case, the thickness of the metal deposition layer is typically greater than or equal to 20 μm, which can improve the energy density and capacity of the battery cell. Corresponding to the thickness of the metal deposition layer, the thickness of the first insulating structure can be set to be greater than the thickness of the metal deposition layer. For example, the thickness of the first insulating structure is typically greater than or equal to 25 μm, so as to effectively prevent metal from overflowing from the first edge region, thereby reducing the overlap between the positive and negative electrode sheets caused by overflowing metal.

[0012] The single-sided areal density of the positive electrode sheet is limited to less than or equal to 1500g / 1540.25mm. 2 This reduces the risk of cracking and detachment of the positive electrode film, thereby improving the performance and cycle life of the battery cell. Furthermore, excessively high areal density on one side of the positive electrode can lead to an excessively thick positive electrode film, potentially increasing ion migration resistance and affecting the battery cell's capacity. Additionally, a single-sided areal density of less than or equal to 1500g / 1540.25mm is preferable. 2 In this case, the thickness of the metal deposition layer is typically less than or equal to 90 μm, which can limit the volume expansion of the negative electrode sheet to prevent excessive expansion, improve structural stability, and thus improve the performance and cycle life of the battery cell. Corresponding to the thickness of the metal deposition layer, the thickness of the first insulating structure can be set to be greater than the thickness of the metal deposition layer. For example, the thickness of the first insulating structure is typically less than or equal to 95 μm, in order to save the space occupied by the first insulating structure and improve the energy density of the battery cell.

[0013] In some embodiments, the areal density of the positive electrode sheet ranges from [600g / 1540.25mm²]. 2 800g / 1540.25mm 2 The thickness of the metal deposition layer ranges from [32μm, 46μm], and the thickness of the first insulating structure ranges from [37μm, 51μm]. Further limiting the range of the areal density on one side of the positive electrode sheet further restricts the thickness of the metal deposition layer and the thickness of the first insulating structure. This can improve the energy density of the battery cell, facilitate uniform coating, reduce processing difficulty, and improve the processing efficiency of the battery cell. It can also reduce the risk of cracking and peeling of the positive electrode film layer, thereby improving the performance and cycle life of the battery cell.

[0014] In some embodiments, the first insulating structure includes an insulating material that satisfies at least one of the following conditions: the volume distribution particle size Dv50 of the insulating material is less than or equal to 2 μm; the tap density of the insulating material is in the range of [0.8 g / cm³]. 3 2.0g / cm 3 ]; and the specific surface area of ​​the insulating material ranges from [3m] to [3m].2 / g, 25m 2 / g]. The volumetric particle size Dv50 of the insulating material is typically less than or equal to 2μm. A smaller volumetric particle size can improve the adhesion of the first insulating structure to the surface of the negative electrode current collector, thereby improving structural stability. The tap density of the insulating material is set to be greater than or equal to 0.8g / cm³. 3 The particles are densely packed, resulting in a high density of the primary insulation structure and more stable insulation performance; the tap density of the insulation material is set to be less than or equal to 2.0 g / cm³. 3 This design limits the interparticle gaps to prevent them from becoming too small, making it easier for the adhesive to fill them and thus improving the mechanical strength of the first insulation structure. The specific surface area of ​​the insulating material is set to be greater than or equal to 3 m². 2 / g can reduce the difficulty of material selection and the risk of detachment caused by a decrease in the bonding strength between the insulating material and the adhesive, thereby improving the insulation performance of the first insulation structure; the specific surface area of ​​the insulating material is set to be less than or equal to 25m². 2 / g can reduce side reactions between the insulating material and the electrolyte, thereby improving the stability and insulation of the first insulating structure.

[0015] In some embodiments, the first insulating structure includes an adhesive, with the adhesive content ranging from [10%, 20%] and the thickness ranging from [25μm, 50μm] based on the total weight of the first insulating structure; or, with the adhesive content ranging from [20%, 40%] and the thickness ranging from [50μm, 95μm] based on the total weight of the first insulating structure. When the adhesive content is relatively low, the thickness of the first insulating structure should not be too large to maintain good structural strength and improve its insulation performance even with relatively low adhesive force. Conversely, when the adhesive content is relatively high, the thickness of the first insulating structure is also larger to improve adhesive force, allowing the thicker first insulating structure to also have good structural strength, thereby improving its insulation performance. Therefore, the adhesive content in the material of the first insulating structure can be reasonably set according to different application scenarios, such as different requirements for the thickness of the first insulating structure.

[0016] In some embodiments, the electrode assembly includes a plurality of positive electrode sheets and a plurality of negative electrode sheets, which are stacked along the thickness direction of the negative electrode sheets. The first surface also includes two second edge regions, with the middle region located between the two second edge regions along a second direction perpendicular to the first direction. Each of the two second edge regions is provided with a second insulating structure. The second insulating structure can reduce metal accumulation in the second edge regions of the negative electrode sheets. Furthermore, the thickness of the second insulating structure is greater than the thickness T of the metal deposition layer, which can prevent metal from overflowing from the second edge regions, thereby reducing the overlap between the positive and negative electrode sheets caused by overflowing metal. Especially for stacked electrode assemblies, the insulating structure provided around the negative electrode sheets can effectively prevent metal from overflowing from all directions, thereby reducing the overlap between the positive and negative electrode sheets caused by overflowing metal, effectively reducing the risk of internal short circuits in the battery cell after formation, improving the first formation efficiency, thereby improving the performance and structural stability of the battery cell, and also improving the cycle life of the battery cell.

[0017] In some embodiments, the thickness of the second insulating structure is greater than the thickness of the metal deposition layer, so that the second insulating structure can effectively prevent metal from overflowing from the second edge region, thereby reducing the risk of overlap between the positive and negative electrodes caused by overflowing metal.

[0018] In some embodiments, the width of the second insulating structure along the second direction ranges from [0.1 mm to 3 mm]. Setting the width of the second insulating structure to be greater than or equal to 0.1 mm enables it to effectively prevent metal from overflowing from the second edge region where the second insulating structure is located, thereby reducing the overlap between the positive and negative electrode sheets caused by overflowing metal. Setting the width of the second insulating structure to be less than or equal to 3 mm limits the area of ​​the first surface of the negative electrode sheet occupied by the second insulating structure, thereby increasing the energy density of the battery cell.

[0019] In some embodiments, the positive electrode and the negative electrode are wound around a winding shaft to form the electrode assembly, wherein the direction of the winding shaft is the first direction. Alternatively, the electrode assembly includes a plurality of positive electrode sheets, and the negative electrode sheet includes at least one bent segment and a plurality of stacked segments interconnected, each bent segment connecting two stacked segments, and the plurality of stacked segments and the plurality of positive electrode sheets are stacked together along the thickness direction of the positive electrode sheets. Since the starting and ending ends of the negative electrode sheets in the above two types of electrode assemblies are generally longer than the starting and ending ends of the positive electrode sheets, and the portion of the negative electrode sheet that extends beyond the positive electrode sheet can be used to prevent metal leakage, a second insulating structure can be omitted to simplify the structure.

[0020] In some embodiments, the positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector, wherein the orthographic projection of the positive electrode film layer is located within the orthographic projection range of the intermediate region along the thickness direction of the negative electrode. This can reduce the amount of metal deposited near the first edge region and reduce the risk of metal overflowing from the first edge region.

[0021] 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 of the first aspect.

[0022] 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.

[0023] In some embodiments, the electrical equipment is a vehicle, a ship, or a spacecraft. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a vehicle according to one embodiment of this application;

[0025] Figure 2 This is an exploded view of a portion of the structure of a battery device according to an embodiment of this application;

[0026] Figure 3 This is an exploded structural diagram of a partial structure of a battery cell according to an embodiment of this application;

[0027] Figure 4 This is a cross-sectional schematic diagram of an electrode assembly according to an embodiment of this application;

[0028] Figure 5 This is another cross-sectional schematic diagram of an electrode assembly according to an embodiment of this application;

[0029] Figure 6 This is another cross-sectional schematic diagram of an electrode assembly according to an embodiment of this application;

[0030] Figure 7 This is a cross-sectional schematic diagram of an electrode assembly according to one embodiment of this application from another direction;

[0031] Figure 8 This is a schematic diagram of a partial structure of the negative electrode sheet according to an embodiment of this application;

[0032] Figure 9 This is a schematic diagram of another partial structure of the negative electrode sheet according to one embodiment of this application;

[0033] Figure 10 This is another cross-sectional schematic diagram of an electrode assembly according to an embodiment of this application.

[0034] The accompanying drawings are not drawn to scale. Detailed Implementation

[0035] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0038] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0039] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0040] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0041] 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.

[0042] In this application, "multiple" refers to two or more (including two), and similarly, "multiple groups" refers to two or more (including two), and "multiple pieces" refers to two or more (including two).

[0043] 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.

[0044] The battery cell can be a lithium-ion battery, a sodium-ion battery, a sodium-lithium-ion battery, a lithium metal battery, a sodium metal battery, a lithium-sulfur battery, etc., and the embodiments of this application are not limited to this.

[0045] For "self-generated negative electrode" negative electrode sheets, the negative electrode current collector is relatively thin, typically 8 to 20 μm. During stacking, more layers need to be stacked to increase energy density. However, more layers affect production efficiency and increase manufacturing costs. Furthermore, due to the use of more substrates and separators, the goal of low cost cannot be achieved. Therefore, increasing the thickness of the positive electrode sheet can effectively reduce the number of stacked layers, thereby reducing costs. However, increasing the thickness of the positive electrode sheet leads to a simultaneous increase in the thickness of the metal deposited on the surface of the negative electrode sheet. Excessively thick metal accumulating at the edges of the negative electrode sheet may be squeezed out and bypass the separator, connecting the positive and negative electrodes.

[0046] Therefore, embodiments of this application provide a battery cell, a battery device, and an electrical appliance that can solve the aforementioned problems. The battery cell implemented in this application includes an electrode assembly comprising a positive electrode and a negative electrode, wherein the negative electrode includes a negative current collector. The negative current collector includes a negative electrode body and a negative electrode tab. The negative electrode body includes at least one first surface, the first surface including a central region and two first edge regions. Along a first direction, the central region is located between the two edge regions, and the negative electrode tab extends from the first edge regions of the negative electrode body. The central region has a metal deposition layer, and at least one of the two first edge regions is provided with a first insulating structure. By providing a first insulating structure in at least one first edge region, the metal will be deposited away from the first edge region and preferentially form a metal deposition layer in the middle region. This reduces the accumulation of metal in the first edge region of the negative electrode where the first insulating structure is provided. The first insulating structure can also reduce the overflow of metal from the first edge region, thereby reducing the overlap between the positive and negative electrodes caused by the overflowing metal. This can reduce the risk of internal short circuits in the battery cell after formation, improve the first formation efficiency, improve the cycle life of the battery cell, and improve the reliability of the battery cell.

[0047] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use battery devices.

[0048] Electrical devices 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 devices.

[0049] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0050] For example, such as Figure 1The diagram shown is a structural schematic of a vehicle 1 according to one embodiment of this application. Vehicle 1 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A motor 60, a controller 70, and a battery device 10 can be installed inside vehicle 1. The controller 70 controls the battery device 10 to supply power to the motor 60. 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, to meet the electrical system requirements of vehicle 1, such as for 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.

[0051] Figure 2 An exploded view of a portion of the structure of the battery device 10 according to an embodiment of this application is shown. Figure 2 As shown, the battery device 10 of this application embodiment may include a plurality of battery cells 20 to meet different power usage requirements. The shape of the battery cell 20 in this application embodiment can be set according to actual application. For example, the battery cell 20 can be as follows: Figure 2 The cuboid shown can also be different. Figure 2 The embodiments shown are cylindrical or other shapes, but are not limited to these.

[0052] In some embodiments, the battery device 10 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 20, which are connected in series, parallel, or mixed connections via a busbar.

[0053] In some embodiments, the battery cell assembly is typically formed by arranging a plurality of battery cells 20.

[0054] As an example, the battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells 20 into a single module. As an example, the battery module can be formed by bundling multiple battery cells 20 together with cable ties.

[0055] In some embodiments, the battery device 10 may be a battery pack, which includes a housing and one or more individual battery cell assemblies housed within the housing 11. Figure 2As shown, 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 interior, 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... Figure 2 As shown, 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 chamber, 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.

[0056] For example, unlike Figure 2 As shown, either the first housing portion 111 or the second housing portion 112 may have only one 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.

[0057] Figure 3 An exploded view of a portion of the battery cell 20 according to an embodiment of this application is shown. For example, Figure 3 The battery cell 20 shown can be as follows: Figure 2 Any one of the battery cells 20 in the battery device 10 shown. As an example, the battery cell 20 in this embodiment 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 does not have any particular limitations.

[0058] like Figure 3As shown, for ease of explanation, this application embodiment takes a cuboid battery cell 20 as an example, and defines three directions based on the cuboid battery cell 20: the length direction X of the battery cell 20, the thickness direction Y of the battery cell 20, and the height direction Z of the battery cell 20. The length direction X, the thickness direction Y, and the height direction Z are perpendicular to each other, and the size of the battery cell 20 in its length direction X is greater than the size in its thickness direction Y.

[0059] In some embodiments, such as Figure 3 As shown, the battery cell 20 in this embodiment may include a casing 21. The casing 21 may be a steel casing, an aluminum casing, a plastic casing (such as polypropylene), a composite metal casing (such as a copper-aluminum composite casing), or an aluminum-plastic film, etc. In some embodiments, the casing 21 may be a sealed structure or a non-sealed structure. As an example, when the casing 21 is a non-sealed structure, the casing 21 serves to protect the internal electrode assembly 22, and a sealing bag is also included between the casing 21 and the electrode assembly 22. The sealing bag is used to encapsulate the electrode assembly 22 and the electrolyte. Specifically, the sealing bag may be a bag-shaped insulating component or an aluminum-plastic film. When the casing 21 is a sealed structure, it is used to encapsulate the electrode assembly 22 and the electrolyte, etc.

[0060] In some embodiments, the housing 21 includes a housing 211 and an end cap 212. The housing 211 has an opening 2111, and the end cap 212 covers the opening 2111. The housing 211 may have one or more openings 2111. The end cap 212 may also have one or more.

[0061] In some implementations, such as Figure 3 As shown, the battery cell 20 also includes at least one electrode terminal 23, which is used to electrically connect to the electrode assembly 22 inside the battery cell 20 to output the electrical energy of the battery cell 20. The electrode terminal 23 can be directly connected to the tab 222 of the electrode assembly 22, or indirectly connected to the tab 222 through a current collector. The battery cell 20 may include at least one positive electrode terminal 231 and at least one negative electrode terminal 232, wherein the positive electrode terminal 231 is used to electrically connect to the positive electrode tab 312, and the negative electrode terminal 232 is used to electrically connect to the negative electrode tab 412.

[0062] In this embodiment of the application, all electrode terminals 23 of the battery cell 20 can be located on any one or more walls of the battery cell 20, that is, different electrode terminals 23 can be located on the same wall or different walls of the battery cell 20. For example, Figure 3 As shown, the embodiments of this application mainly take the battery cell 20 including two electrode terminals 23 as an example, and the two electrode terminals 23 are both located on the same wall of the battery cell 20. Here, it is taken that the two electrode terminals 23 are both located on the end cover 212 as an example, but the embodiments of this application are not limited to this.

[0063] like Figure 3 As shown, the battery cell 20 in this embodiment of the application further includes at least one electrode assembly 22, wherein each electrode assembly 22 may be a wound structure or a stacked structure.

[0064] Figure 4 A cross-sectional schematic diagram of the electrode assembly 22 according to an embodiment of this application is shown, wherein... Figure 4 The electrode assembly 22 shown is a wound electrode assembly 22. For example... Figure 4 As shown, the electrode assembly 22 may include a positive electrode 30 and a negative electrode 40, which are wound around a winding shaft to form the electrode assembly 22. The tabs 222 of the wound electrode assembly 22 typically extend along the direction of its winding shaft. Figure 4 Taking the direction of the winding axis of the electrode assembly 22 as the height direction Z of the battery cell 20 as an example, the embodiments of this application are not limited to this.

[0065] In some embodiments, the shape of the wound electrode assembly 22 can be configured according to the actual application. For example, the wound electrode assembly 22 can be cylindrical, or, as... Figure 4 As shown, the cross-section of the electrode assembly 22 can also be approximated as oval.

[0066] Figure 5 and Figure 6 Two other possible cross-sectional schematic diagrams of the electrode assembly 22 according to embodiments of this application are shown, wherein... Figure 5 and Figure 6 The electrode assembly 22 shown is a stacked electrode assembly 22. For example... Figure 5 As shown, the electrode assembly 22 may include a plurality of first electrode sheets stacked together. The electrode assembly 22 also includes a second electrode sheet, which includes interconnected bent sections and a plurality of stacked sections. Each bent section connects to two stacked sections, and each stacked section connects to one or two bent sections. The plurality of stacked sections are stacked with the plurality of first electrode sheets, thereby forming a stacked electrode assembly 22. Figure 5 Taking the stacked configuration of multiple segments of the electrode assembly 22 and multiple first electrode sheets stacked along the thickness direction Y of the battery cell 20 as an example, the embodiments of this application are not limited to this.

[0067] In some embodiments, the first electrode and the second electrode have opposite polarities, for example, as shown in the figure. Figure 5As shown, the first electrode can be a positive electrode 30, and the second electrode is a negative electrode 40. Specifically, the electrode assembly 22 includes multiple positive electrode 30s, and the negative electrode 40 includes at least one bent section 401 and multiple stacked sections 402 connected to each other. Each bent section 401 connects two stacked sections 402. The multiple stacked sections 402 and the multiple positive electrode 30 are stacked along the thickness direction of the positive electrode 30, wherein the thickness direction of the positive electrode 30 is also the thickness direction of the stacked sections 402. Furthermore, the extension direction of the tab 222 of this type of electrode assembly 22 is perpendicular to the thickness direction of the positive electrode 30, that is, perpendicular to the stacking direction of the multiple stacked sections 402 and the multiple positive electrode 30.

[0068] like Figure 6 As shown, the electrode assembly 22 may further include multiple positive electrode plates 30 and multiple negative electrode plates 40, which are stacked to form another type of stacked electrode assembly 22. The stacking direction of the multiple positive electrode plates 30 and multiple negative electrode plates 40 is the thickness direction of both the positive electrode plates 30 and the negative electrode plates 40, and this stacking direction is perpendicular to the extension direction of the tabs 222 of this type of electrode assembly 22. For example, Figure 6 Taking the electrode assembly 22 as an example, where multiple positive electrode plates 30 and multiple negative electrode plates 40 are stacked along the thickness direction Y of the battery cell 20, the embodiments of this application are not limited to this.

[0069] It should be understood that the electrode assembly 22 in the embodiments of this application can be any of the electrode assemblies described above. Figure 7 A cross-sectional schematic diagram of the electrode assembly 22 according to an embodiment of this application is shown in another direction, wherein, Figure 7 Only a cross-sectional schematic diagram of a portion of the electrode plates of the electrode assembly 22 is shown. Figure 7 The cross-section shown is perpendicular to, as Figures 4 to 6 The cross-section shown, for example, Figures 4 to 6 The cross-section shown is taken as an example in the height direction Z, which is perpendicular to the battery cell 20. Figure 7 The cross-section shown is taken as an example with the length direction X perpendicular to the battery cell 20. Figure 8 This illustration shows a partial structure of the negative current collector 41 included in the negative electrode sheet 40 according to an embodiment of this application. For example, Figure 8 It can be Figure 7 The diagram shows a partial structure of the negative electrode current collector 41 of the negative electrode plate 40 included in the electrode assembly 22.

[0070] In the embodiments of this application, such as Figure 7 and Figure 8As shown, the battery cell 20 includes an electrode assembly 22, which includes a positive electrode 30 and a negative electrode 40. The negative electrode 40 includes a negative current collector 41, which includes a negative electrode body 411 and a negative electrode tab 412. The negative electrode body 411 includes at least one first surface 4110, which includes a middle region 4111 and two first edge regions 4112. Along a first direction, the middle region 4111 is located between the two first edge regions 4112, and the negative electrode tab 412 extends from the first edge region 4112 of the negative electrode body 411. The middle region 4111 is provided with a metal deposition layer 43, and at least one of the two first edge regions 4112 is provided with a first insulating structure 42.

[0071] In this embodiment, the negative electrode 40 includes a negative current collector 41. As an example, the negative current collector 41 can be a metal foil, a conductive polymer material, a carbon material, or a composite current collector. For example, as a metal foil, it can be a pure metal, an alloy, or a surface-treated metal, including but not limited to stainless steel, copper, aluminum, nickel, titanium, or silver. The composite current collector may include a polymer material substrate and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0072] The negative electrode current collector 41 in this embodiment includes a negative electrode body 411 and a negative electrode tab 412 protruding from the negative electrode body 411, wherein the negative electrode body 411 is used to form the main body 221 of the electrode assembly 22. For example, Figure 7 A cross-sectional schematic diagram of the negative electrode body 411 and the negative electrode tab 412 is shown. Figure 8 A schematic diagram of the surface of the negative electrode current collector 41 is shown, wherein, Figure 8 The surface of the negative electrode current collector 41 shown includes a first surface 4110 of the negative electrode body 411, which is the surface of the negative electrode body 411 facing the positive electrode 30 and perpendicular to the thickness direction of the negative electrode 40.

[0073] The negative electrode body 411 of this application embodiment may include at least one first surface 4110. For any one of the first surfaces 4110, the first surface 4110 includes a central region 4111 and two first edge regions 4112. Along a first direction, the central region 4111 is located between the two first edge regions 4112, and the negative electrode tab 412 extends from the first edge regions 4112 of the negative electrode body 411. That is, the first direction of this application embodiment is the distribution direction of the central region 4111 and the first edge regions 4112 within the first surface 4110, and it is also the extension direction of the negative electrode tab 412 relative to the negative electrode body 411. For example, for such... Figure 4 The spiral-wound electrode assembly 22 shown typically extends in the direction of the winding axis; therefore, this first direction is also the direction of the winding axis. For example, for a spiral-wound electrode assembly 22... Figure 5 and Figure 6 The stacked electrode assembly 22 shown has tabs 222 extending in a direction that is generally perpendicular to the stacking direction of the electrodes. Therefore, this first direction is also perpendicular to the stacking direction of the electrodes.

[0074] In some embodiments, such as Figure 7 and Figure 8 As shown, for ease of explanation, the accompanying drawings of this application embodiment mainly take the height direction Z of the battery cell 20 as an example, but since the arrangement direction of the electrode assembly 22 inside the battery cell 20 is not unique, the embodiments of this application are not limited to this. In addition, when the first direction is the height direction Z of the battery cell 20, the negative electrode tab 412 protrudes from the negative electrode body 411 along the height direction Z of the battery cell 20; and along the height direction Z of the battery cell 20, the middle region 4111 is located between the two first edge regions 4112.

[0075] In this application, metal ions are released from the positive electrode 30 of the battery cell 20 and deposited on the surface of the negative electrode 40 to form a metal deposition layer 43. Specifically, during the processing, a metal layer can be pre-formed on the surface of the negative current collector 41 of the negative electrode 40, or no metal layer can be formed on the surface of the negative current collector 41. After each charge of the battery cell 20, the active material on the surface of the positive electrode 30 is released and deposited on the surface of the negative current collector 41 to form a metal layer, that is, a metal deposition layer 43 of a certain thickness is formed on the surface of the negative current collector 41. In this embodiment, the metal deposition layer 43 refers to the metal layer on the surface of the negative current collector 41 of the negative electrode 40 of the battery cell 20 in a fully charged state. If a metal layer is pre-formed on the surface of the negative current collector 41 of the negative electrode 40 during the processing, the metal deposition layer 43 includes the pre-formed metal layer and the metal layer formed by the release of active material from the surface of the positive electrode 30.

[0076] By providing a first insulating structure 42 in at least one of the two first edge regions 4112, the metal will be deposited away from the first edge region 4112 and preferentially form a metal deposition layer 43 in the middle region 4111. This can reduce the accumulation of metal in the first edge region 4112 of the negative electrode 40 where the first insulating structure 42 is provided. The first insulating structure 42 can also reduce the overflow of metal from the first edge region 4112 where it is located, thereby reducing the overlap between the positive and negative electrodes caused by the overflowing metal. This can reduce the risk of internal short circuit in the battery cell 20 after formation, improve the first formation efficiency, improve the cycle life of the battery cell 20, and improve the reliability of the battery cell 20.

[0077] In some embodiments, the two first edge regions 4112 are respectively provided with a first insulating structure 42, that is, the first insulating structure 42 is provided on both sides of the first surface 4110 along the first direction, so that when the metal is deposited, the metal deposition layer 43 is preferentially formed in the middle region 4111, while the first edge regions 4112 far away from the sides can jointly restrict the metal overflow from both sides of the negative electrode sheet 40, further reducing the risk of overlap between the positive and negative electrode sheets caused by metal overflow, so as to effectively improve the reliability of the battery cell 20.

[0078] In some embodiments, the first insulating structure 42 may be provided on only one of the two first edge regions 4112 of the first surface 4110, while the other first edge region 4112 may not have the first insulating structure 42 provided. For example, the negative electrode tab 412 is typically located on one side of the first surface 4110, so the two first edge regions 4112 of the first surface 4110 include one first edge region 4112 closer to the negative electrode tab 412 and one first edge region 4112 farther from the negative electrode tab 412, wherein the first insulating structure 42 may be provided on either first edge region 4112. Providing the first insulating structure 42 on only one first edge region 4112 can reduce the area and area of ​​the first insulating structure 42 provided on the negative electrode sheet 40, thereby simplifying the process of processing the negative electrode sheet 40.

[0079] In some embodiments, the thickness T1 of the first insulating structure 42 is greater than the thickness T2 of the metal deposition layer 43, where the thickness T2 of the metal deposition layer 43 is the thickness of the metal deposition layer 43 when the battery cell 20 is fully charged. By providing a thicker first insulating structure 42, metal can be prevented from overflowing from the first edge region 4112, thereby effectively reducing the overlap between the positive and negative electrode plates caused by overflowing metal. This can reduce the risk of internal short circuits in the battery cell 20 after formation, improve the first formation efficiency, thereby improving the performance and structural stability of the battery cell 20, and also improving the cycle life of the battery cell 20.

[0080] It should be understood that the thickness T1 of the first insulating structure 42 in the embodiments of this application may refer to the average thickness of the first insulating structure 42 disposed in each first edge region 4112; the thickness T2 of the metal deposition layer 43 may refer to the average thickness of the metal deposition layer 43 deposited in the middle region 411 when the battery cell 20 is fully charged.

[0081] It should be understood that the difference between the thickness T1 of the first insulating structure 42 and the thickness T2 of the metal deposition layer 43 can be set according to the actual application. For example, the range of the difference between the thickness T1 of the first insulating structure 42 and the thickness T2 of the metal deposition layer 43 is (0 μm, 10 μm). By limiting the difference between the thickness T1 of the first insulating structure 42 and the thickness T2 of the metal deposition layer 43 to less than or equal to 10 μm, on the one hand, the volume and weight of the electrode assembly 22 can be limited to improve the energy density of the battery cell 20; on the other hand, if the difference is too large, the thickness T1 of the first insulating structure 42 will be too large, affecting the deposition effect of the metal deposition layer 43, leading to a deterioration of the deposition morphology, and thus affecting the performance of the electrode assembly 22.

[0082] In some embodiments, the difference between the thickness T1 of the first insulating structure 42 and the thickness T2 of the metal deposition layer 43 ranges from [2μm to 8μm]. This can effectively prevent metal from overflowing from the first edge region 4112, thereby reducing the risk of internal short circuits in the battery cell 20 after formation, and also improving the energy density and performance of the battery cell 20.

[0083] In some embodiments, the difference between the thickness T1 of the first insulating structure 42 and the thickness T2 of the metal deposition layer 43 can be any of the following values ​​or between any two of the following values: 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, or 10μm.

[0084] Figure 9 A schematic diagram of the structure of the negative electrode 40 according to an embodiment of this application is shown, for example, Figure 9 It can be Figure 7 The electrode assembly 22 shown here includes another possible structural schematic diagram of the negative electrode plate 40.

[0085] In some embodiments, the first surface 4110 further includes two second edge regions 4113; along a second direction, a middle region 4111 is located between the two second edge regions 4113, and the second direction is perpendicular to the first direction; the two second edge regions 4113 are respectively provided with a second insulating structure. For example... Figure 9 For example Figure 6Taking the negative electrode 40 of the stacked electrode assembly 22 as an example, multiple positive electrode 30s and multiple negative electrode 40s are stacked along the thickness direction of the negative electrode 40. Furthermore, in this embodiment, the second direction within the first surface 4110 is perpendicular to the first direction; that is, the first direction, the second direction, and the thickness direction of the negative electrode 40 are mutually perpendicular. In this embodiment, if the first direction is the height direction Z of the battery cell 20, then the second direction is the length direction X of the battery cell 20. Therefore, along the length direction X of the battery cell 20, the middle region 4111 is located between the two second edge regions 4113. Alternatively, for example... Figure 4 and Figure 5 The electrode assembly 22 shown has a second edge region 4113, which is the beginning and end of the extension direction of the negative electrode 40.

[0086] The second insulating structure in this embodiment is located in the second edge region 4113. This second insulating structure can reduce the accumulation of metal in the second edge region 4113 of the negative electrode sheet 40; and the second insulating structure can reduce the leakage of metal from the second edge region 4113, thereby reducing the overlap between the positive and negative electrodes caused by the overflowing metal, especially for... Figure 6 The stacked electrode assembly 22 shown can effectively reduce the leakage of metal from all directions by setting an insulating structure around the negative electrode 40, thereby reducing the overlap between the positive and negative electrodes caused by the leakage metal, effectively reducing the risk of internal short circuit in the battery cell 20 after formation, improving the first formation efficiency, thereby improving the performance and structural stability of the battery cell 20, and also improving the cycle life of the battery cell 20.

[0087] In some embodiments, the thickness of the second insulating structure is greater than the thickness T2 of the metal deposition layer 43, so that the second insulating structure can effectively prevent metal from overflowing from the second edge region 4113, thereby reducing the risk of overlap between the positive and negative electrodes caused by overflowing metal.

[0088] It should be understood that the difference between the thickness of the second insulating structure and the thickness T2 of the metal deposition layer 43 can be set according to the actual application. For example, the range of the difference between the thickness of the second insulating structure and the thickness T2 of the metal deposition layer 43 is (0 μm, 10 μm). By limiting the difference between the thickness of the second insulating structure and the thickness T2 of the metal deposition layer 43 to be less than or equal to 10 μm, on the one hand, the volume and weight of the electrode assembly 22 can be limited to improve the energy density of the battery cell 20. On the other hand, if the difference is too large, the thickness of the second insulating structure will be too large, affecting the deposition effect of the metal deposition layer 43, leading to a deterioration of the deposition morphology, and thus affecting the performance of the electrode assembly 22.

[0089] In some embodiments, the difference between the thickness of the second insulating structure and the thickness T2 of the metal deposition layer 43 ranges from [2μm to 8μm]. This can effectively prevent metal from overflowing from the second edge region 4113, thereby reducing the risk of internal short circuits in the battery cell 20 after formation, and can also improve the energy density and performance of the battery cell 20.

[0090] In some embodiments, the difference between the thickness of the second insulating structure and the thickness T2 of the metal deposition layer 43 can be any of the following values ​​or between any two of the following values: 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, or 10μm.

[0091] In some embodiments, for such Figure 4 and / or Figure 5 The electrode assembly 22 shown may also omit the second insulating structure at the beginning and end of the extension direction of its negative electrode 40. Specifically, because the beginning and end of the extension direction of the negative electrode 40 of this type of electrode assembly 22 are typically longer than the beginning and end of the extension direction of the positive electrode 30, for example, as shown... Figure 4 Taking the wound electrode assembly 22 as an example, the starting end of the winding of the negative electrode 40 is typically about 4-5 mm longer than the starting end of the winding of the positive electrode 30, and the ending end of the winding of the negative electrode 40 is typically about 5-6 mm longer than the ending end of the winding of the positive electrode 30. Therefore, the portion of the negative electrode 40 extending beyond the positive electrode 30 can be used to prevent metal leakage. Thus, a second insulating structure is not required to simplify the structure. However, to improve the energy density of the battery cell 20, the elongation of the negative electrode 40 relative to the positive electrode 30 in the direction in which the tabs 222 of the electrode assembly 22 extend (i.e., the first direction) is very limited, typically only 1-2 mm. Therefore, a first insulating structure 42 can be added to prevent metal leakage.

[0092] It should be understood that the first insulating structure 42 and the second insulating structure in the embodiments of this application may be configured in the same or similar ways. The following description mainly uses the first insulating structure 42 as an example, but the relevant description is also applicable to the second insulating structure. For the sake of brevity, they will not be described in detail.

[0093] It should be understood that the thickness T1 of the first insulating structure 42 and the thickness T2 of the metal deposition layer 43 in the embodiments of this application can be set according to actual applications. For example, the thickness T2 of the metal deposition layer 43 and / or the thickness T1 of the first insulating structure 42 can be determined according to the relevant parameters of the positive electrode 30.

[0094] In this embodiment, the positive electrode 30 includes a positive current collector 31, which can be made of metal foil, conductive polymer material, carbon material, or composite current collector. For example, as a metal foil, pure metal, alloy, or surface-treated metal can be used, including but not limited to stainless steel, copper, aluminum, nickel, titanium, or silver. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0095] Furthermore, the positive electrode 30 also includes a positive electrode film layer 32 disposed on at least one side of the positive electrode current collector 31. Specifically, the positive electrode current collector 31 has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer 32 is disposed on either or both of the two opposite surfaces of the positive electrode current collector 31, for example, Figure 7 Taking the thickness direction of the positive current collector 31 as the thickness direction Y of the battery cell 20 as an example. The area of ​​the positive current collector 31 of the positive electrode sheet 30 where the positive electrode film layer 32 is provided is used to form the main body 221 of the electrode assembly 22, and the area where the positive electrode film layer 32 is not provided is used to form the positive electrode tab 312 of the electrode assembly 22.

[0096] As an example, the positive electrode film 32 includes a positive electrode active material, which may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM)523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 )), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by modification methods such as doping or coating based on the above-mentioned substances.

[0097] In some embodiments, the thickness T1 of the first insulating structure 42 can be determined according to the positive electrode film layer 32 of the positive electrode 30.

[0098] For example, the thickness of the positive electrode film 32 is denoted as H, usually in mm; the capacity per unit area of ​​the positive electrode film 32 is denoted as M, usually in mAh / cm². 2 The theoretical specific capacity of the metal deposition layer 43 deposited on the negative electrode plate 40 during charging of the battery cell 20 is denoted as C, and the unit is usually mAh / g. For example, when the metal deposition layer 43 is sodium metal, its theoretical specific capacity is usually 1166 mAh / g, and when the metal deposition layer 43 is lithium metal, its theoretical specific capacity is usually 3860 mAh / g. The density of the metal deposition layer 43 is denoted as ρ, and the unit is usually g / cm³. 3 The thickness T1 of the first insulating structure 42 usually satisfies: M / (C×ρ)<T1<HM / (C×ρ), so that the first insulating structure 42 can effectively prevent metal from overflowing.

[0099] In some embodiments, the thickness T2 of the metal deposition layer 43 can also be determined based on the relevant parameters of the positive electrode 30.

[0100] For example, the thickness T2 of the metal deposition layer 43 is determined to be [(a*b*c) / C] / ρ, where a is the areal density of the positive electrode 30 on one side, in g / 1540.25mm. 2b represents the solid content of the slurry in the positive electrode 30, which is typically 95%; c represents the specific charging capacity of the electrode assembly 22, typically in mAh / g; C represents the theoretical specific capacity of the metal deposition layer 43, typically in mAh / g. For example, when the metal deposition layer 43 is sodium metal, its theoretical specific capacity is typically 1166 mAh / g; when the metal deposition layer 43 is lithium metal, its theoretical specific capacity is typically 3860 mAh / g; ρ represents the density of the metal deposition layer 43, typically in g / cm³. 3 For example, when the metal deposition layer 43 is sodium metal, the density is 0.968 g / cm³. 3 When the metal deposition layer 43 is lithium metal, the density is 0.534 g / cm³. 3 .

[0101] In some embodiments, the thickness T1 of the first insulating structure 42 and / or the thickness T2 of the metal deposition layer 43 can be determined based on other parameters of the positive electrode 30. For example, the thickness T2 of the metal deposition layer 43 and the thickness T1 of the first insulating structure 42 can be determined based on the areal density of one side of the positive electrode 30.

[0102] It should be understood that the areal density of the positive electrode 30 in this embodiment can be set according to actual application. In this document, "areal density" refers to the mass of other materials on a unit area of ​​the electrode, excluding the current collector. For example, the mass of the positive electrode film 32 on a unit area of ​​the positive electrode 30.

[0103] In some embodiments, the areal density of the positive electrode 30 on one side ranges from [400g / 1540.25mm²]. 2 1500g / 1540.25mm 2 The thickness T2 of the metal deposition layer 43 ranges from [20 μm to 90 μm], and the thickness T1 of the first insulating structure 42 ranges from [25 μm to 95 μm]. For example, the metal deposition layer 43 can be sodium metal or lithium metal.

[0104] By limiting the areal density of the positive electrode 30 to be greater than or equal to 400g / 1540.25mm on one side. 2 This means that the coating mass of the positive electrode active material per unit area of ​​the positive electrode sheet 30 is relatively large. This can effectively improve the energy density of the battery cell 20, facilitate uniform coating, reduce processing difficulty, improve production yield, and thus improve the processing efficiency of the battery cell 20. In addition, the areal density of one side of the positive electrode sheet 30 is greater than or equal to 400g / 1540.25mm. 2In this case, the thickness T2 of the metal deposition layer 43 is typically greater than or equal to 20 μm, which can improve the energy density and capacity of the battery cell 20. Corresponding to the thickness T2 of the metal deposition layer 43, the thickness T1 of the first insulating structure 42 can be set to be greater than the thickness T2 of the metal deposition layer 43. For example, the thickness T1 of the first insulating structure 42 is typically greater than or equal to 25 μm, so as to effectively prevent metal from overflowing from the first edge region 4112, thereby reducing the overlap between the positive and negative electrode sheets caused by overflowing metal.

[0105] The areal density of the positive electrode 30 is limited to less than or equal to 1500g / 1540.25mm on one side. 2 This reduces the risk of cracking and detachment of the positive electrode film 32 of the positive electrode 30, thereby improving the performance and cycle life of the battery cell 20. Furthermore, excessively high areal density on one side of the positive electrode 30 can lead to an excessively thick positive electrode film 32, potentially increasing ion migration resistance and affecting the capacity of the battery cell 20. Additionally, a single-sided areal density of less than or equal to 1500g / 1540.25mm is preferable. 2 In this case, the thickness T2 of the metal deposition layer 43 is typically less than or equal to 95 μm, which can limit the volume expansion of the negative electrode sheet 40 to prevent excessive expansion, improve structural stability, and thus improve the performance and cycle life of the battery cell 20. Corresponding to the thickness T2 of the metal deposition layer 43, the thickness T1 of the first insulating structure 42 can be set to be greater than the thickness T2 of the metal deposition layer 43. For example, the thickness T1 of the first insulating structure 42 is typically less than or equal to 95 μm, so as to save the space occupied by the first insulating structure 42 and improve the energy density of the battery cell 20.

[0106] In some embodiments, the areal density of the positive electrode 30 can also be other values. For example, the areal density of the positive electrode 30 can be in the range of [600g / 1540.25mm]. 2 800g / 1540.25mm 2 The thickness T2 of the metal deposition layer 43 ranges from [32μm, 46μm], and the thickness T1 of the first insulating structure 42 ranges from [37μm, 51μm]. Further limiting the range of the areal density on one side of the positive electrode 30 further limits the thickness T2 of the metal deposition layer 43 and the thickness T1 of the first insulating structure 42. This can improve the energy density of the battery cell 20, facilitate uniform coating, reduce processing difficulty, and improve the processing efficiency of the battery cell 20. It can also reduce the risk of cracking and peeling of the positive electrode film 32 of the positive electrode 30, thereby improving the performance and cycle life of the battery cell 20.

[0107] It should be understood that the method for measuring the single-sided areal density of the positive electrode 30 in this application embodiment can be set according to actual application. For example, the single-sided areal density of the positive electrode 30 can be tested by the following method: disassemble the battery cell 20 after discharging to the lower limit cutoff voltage so that the charge state of the battery cell 20 is about 0% SOC, and take the positive electrode 30 obtained from the battery cell 20 as the electrode to be tested. Randomly select N (e.g., 30) unit areas on the electrode to be tested, take the electrode to be tested from each unit area, weigh the mass of the material on one side of the unit area electrode excluding the current collector, sum the mass and divide by N (e.g., 30) to obtain the areal density of the film layer of the electrode to be tested, which is also the single-sided areal density of the positive electrode 30.

[0108] In some embodiments, the areal density of the positive electrode 30 can also be any of the following values ​​or between any of the following values: 400g / 1540.25mm 2 500g / 1540.25mm 2 600g / 1540.25mm 2 700g / 1540.25mm 2 800g / 1540.25mm 2 900g / 1540.25mm 2 1000g / 1540.25mm 2 1100g / 1540.25mm 2 1200g / 1540.25mm 2 1300g / 1540.25mm 2 1400g / 1540.25mm 2 Or 1500g / 1540.25mm 2 .

[0109] In some embodiments, the thickness T2 of the metal deposition layer 43 may be any of the following values ​​or between any of the following values: 20μm, 25μm, 30μm, 32μm, 35μm, 40μm, 45μm, 46μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, or 90μm.

[0110] In some embodiments, the thickness T1 of the first insulating structure 42 may be any of the following values ​​or between any of the following values: 25μm, 30μm, 35μm, 37μm, 40μm, 45μm, 50μm, 51μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, or 95μm.

[0111] It should be understood that other dimensions of the first insulating structure 42 in this application embodiment can also be set according to actual application.

[0112] In some embodiments, the width W1 of the first insulating structure 42 along the first direction ranges from [0.1 mm, 3 mm]. For example, as... Figure 8 As shown, taking the height direction Z of the battery cell 20 as an example, the width W1 of the first insulating structure 42 is set to be greater than or equal to 0.1 mm, which enables the first insulating structure 42 to effectively prevent metal from overflowing from the first edge region 4112 where the first insulating structure 42 is located, thereby reducing the overlap between the positive and negative electrode sheets caused by the overflowing metal; the width W1 of the first insulating structure 42 is set to be less than or equal to 3 mm, which can limit the area of ​​the first surface 4110 of the negative electrode sheet 40 occupied by the first insulating structure 42, thereby improving the energy density of the battery cell 20.

[0113] Similarly, along the second direction, the width W2 of the second insulation structure ranges from [0.1 mm to 3 mm]. For example, as... Figure 9 As shown, taking the length direction X of the battery cell 20 as an example, the width W2 of the second insulating structure is set to be greater than or equal to 0.1 mm, which enables the second insulating structure to effectively prevent metal from overflowing from the second edge region 4113 where the second insulating structure is located, thereby reducing the overlap between the positive and negative electrode sheets caused by the overflowing metal; the width W2 of the second insulating structure is set to be less than or equal to 3 mm, which can limit the area of ​​the first surface 4110 of the negative electrode sheet 40 occupied by the second insulating structure, thereby improving the energy density of the battery cell 20.

[0114] In some embodiments, the width W1 of the first insulating structure 42 can be other values ​​along the first direction; similarly, the width W2 of the second insulating structure can be other values ​​along the second direction. For example, along the first direction, the width W1 of the first insulating structure 42 can be [1.5mm, 2.5mm], which can reduce short circuits caused by metal overflowing from the first edge region 4112 where the first insulating structure 42 is located, and also improve the energy density of the battery cell 20. Similarly, along the second direction, the width W2 of the second insulating structure can also be set to [1.5mm, 2.5mm], which can reduce short circuits caused by metal overflowing from the second edge region 4113 where the second insulating structure is located, and also improve the energy density of the battery cell 20.

[0115] In some embodiments, the value of the width W1 of the first insulating structure 42 along the first direction or the value of the width W2 of the second insulating structure along the second direction may be any of the following values ​​or be between any of the following values: 0.1mm, 0.3mm, 0.5mm, 0.8mm, 1mm, 1.3mm, 1.5mm, 1.8mm, 2mm, 2.3mm, 2.5mm, 2.8mm or 3mm.

[0116] In some embodiments, the widths of the two first insulating structures 42 disposed on both sides of the intermediate region 4111 of the negative electrode current collector 41 along the first direction may be the same or different, for example... Figure 8 Taking the example where the width W1 of the two first insulating structures 42 on both sides is the same, to facilitate processing.

[0117] In some embodiments, the widths of the two second insulating structures disposed on both sides of the intermediate region 4111 of the negative electrode current collector 41 along the second direction may be the same or different, for example... Figure 9 Taking the example where the width W2 of the two second insulating structures on both sides is the same, to facilitate processing.

[0118] In some embodiments, the width W1 of the first insulating structure 42 along the first direction and the width W2 of the second insulating structure along the second direction may be the same or different to adapt to different application scenarios.

[0119] In some embodiments, along the length direction of the negative electrode sheet 40, the size of the first insulating structure 42 can be the same as the size of the negative electrode current collector 41. That is, along the length direction of the negative electrode current collector 41, the first insulating structure 42 can cover the edge of the negative electrode current collector 41, so that the first insulating structure 42 can block metal overflow in the first edge region 4112 of any area of ​​the negative electrode current collector 41, thereby improving the reliability of the battery cell 20.

[0120] In some embodiments, along the width direction of the negative electrode sheet 40, the size of the second insulating structure can be the same as the size of the negative electrode current collector 41. That is, along the width direction of the negative electrode current collector 41, the second insulating structure can cover the edge of the negative electrode current collector 41, so that the second insulating structure can block metal overflow in the second edge region 4113 of any region of the negative electrode current collector 41, thereby improving the reliability of the battery cell 20.

[0121] It should be understood that, in this embodiment of the application, the length direction of the negative electrode current collector 41 is perpendicular to the width direction, and the dimension of the negative electrode current collector 41 in the length direction is greater than the dimension in the width direction. The width direction of the negative electrode current collector 41 is the first direction. For example, as... Figures 8 to 9Taking the width direction of the negative electrode current collector 41 as an example, which is the height direction Z of the battery cell 20, the embodiments of this application are not limited to this.

[0122] It should be understood that the material of the first insulating structure 42 in this application embodiment can be selected according to the actual application.

[0123] In some embodiments, the first insulating structure 42 includes an insulating material that satisfies at least one of the following conditions: the volume distribution particle size Dv50 of the insulating material is less than or equal to 2 μm; the tap density of the insulating material is in the range of [0.8 g / cm³]. 3 2.0g / cm 3 ]; and the specific surface area of ​​the insulating material ranges from [3m 2 / g, 25m 2 / g).

[0124] The volumetric particle size Dv50 of the insulating material is typically less than or equal to 2 μm. A smaller volumetric particle size can improve the adhesion of the first insulating structure 42 to the surface of the negative electrode current collector 41, thereby improving the structural stability.

[0125] Furthermore, the volume distribution particle size Dv50 of the insulating material can also be within the range of [0.001 μm, 0.5 μm]. This not only forms a dense, continuous, and stable first insulating structure 42, but also effectively prevents metal from overflowing from the first edge region 4112 where the first insulating structure 42 is located. Specifically, limiting the volume distribution particle size Dv50 of the insulating material to be greater than or equal to 0.001 μm can reduce the difficulty of material selection, and excessively small particles may adsorb impurities in the electrolyte due to excessively high surface energy, affecting the insulation stability. Limiting the volume distribution particle size Dv50 of the insulating material to be less than or equal to 0.5 μm can further limit the size of the interparticle gaps in the insulating material, reduce corrosion caused by localized areas being immersed in electrolyte, and also limit the surface roughness of the first insulating structure 42, reducing the risk of friction between the surface of the first insulating structure 42 and the separator 50 causing puncture of the separator 50.

[0126] In some embodiments, the value of the volume distribution particle size Dv50 of the insulating material can also be any of the following values ​​or be between any of the following values: 0.001μm, 0.003μm, 0.005μm, 0.008μm, 0.01μm, 0.03μm, 0.05μm, 0.08μm, 0.1μm, 0.3μm, 0.5μm, 0.8μm, 1μm, 1.5μm, or 2μm.

[0127] In some embodiments, the tap density of the insulating material ranges from [0.8 g / cm³]. 3 2.0g / cm 3The tap density of the insulating material should be greater than or equal to 0.8 g / cm³. 3 The particles are densely packed, resulting in a high density of the first insulation structure (42) and more stable insulation performance; the tap density of the insulation material is set to be less than or equal to 2.0 g / cm³. 3 This can limit the gaps between particles to prevent them from becoming too small, making it easier for the adhesive to fill them, thereby improving the mechanical strength of the first insulating structure 42.

[0128] Furthermore, the tap density of the insulating material ranges from [0.95 g / cm³]. 3 1.40 g / cm 3 This can both increase the density of the first insulating structure 42, making the insulation performance more stable, and also improve the mechanical strength of the first insulating structure 42.

[0129] In some embodiments, the tap density of the insulating material may also be any of the following values ​​or fall between any of the following values: 0.8 g / cm³ 3 0.85g / cm 3 0.9g / cm 3 0.95g / cm 3 1g / cm 3 1.2g / cm 3 1.4g / cm 3 1.5g / cm 3 1.6g / cm 3 1.8g / cm 3 Or 2.0g / cm 3 .

[0130] In some embodiments, the specific surface area of ​​the insulating material ranges from [3m² to 10m²]. 2 / g, 25m 2 / g]. The specific surface area of ​​the insulating material is set to be greater than or equal to 3m². 2 / g can reduce the difficulty of material selection and the risk of detachment caused by a decrease in the bonding strength between the insulating material and the adhesive, thereby improving the insulation performance of the first insulating structure 42; the specific surface area of ​​the insulating material is set to be less than or equal to 25m². 2 / g can reduce side reactions between the insulating material and the electrolyte, thereby improving the stability and insulation of the first insulating structure 42.

[0131] Furthermore, the specific surface area of ​​the insulating material ranges from [7m² to 7m²]. 2 / g, 20m 2 / g], to improve the insulation performance and insulation properties of the first insulation structure 42.

[0132] In some embodiments, the specific surface area of ​​the insulating material may also be any of the following values ​​or fall between any of the following values: 3m 2 / g、5m 2 / g、7m 2 / g, 10m 2 / g、13m 2 / g, 15m 2 / g、18m 2 / g、20m 2 / g、23m 2 / g or 25m 2 / g.

[0133] In some embodiments, the first insulating structure 42 includes an insulating material and an adhesive, the ratio of which can be set according to the actual application.

[0134] For example, based on the total weight of the first insulating structure 42, the mass content of the insulating material ranges from [10%, 90%], and the mass content of the adhesive is greater than or equal to 10%. Setting the mass content of the insulating material to be greater than or equal to 10% can improve the insulation performance and structural stability of the first insulating structure 42, effectively preventing metal from overflowing from the first edge region 4112; setting the mass content of the insulating material to be less than or equal to 90%, or setting the mass content of the adhesive to be greater than or equal to 10%, can increase the content of the adhesive, thereby improving the mechanical strength of the first insulating structure 42, enhancing its impact resistance and deformation resistance, and thus improving structural stability.

[0135] Furthermore, based on the total weight of the first insulating structure 42, the mass content of the insulating material ranges from [10%, 80%], and the mass content of the adhesive ranges from [15%, 90%]. By adjusting the mass content of the insulating material and the adhesive, the mass content of the insulating material can improve the insulation of the first insulating structure 42, while the adhesive fills the gaps to make the structure dense and mechanically stable.

[0136] In some embodiments, based on the total weight of the first insulating structure 42, the mass content of the insulating material or the mass content of the adhesive may be any of the following values ​​or between any of the following values: 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%.

[0137] In some embodiments, the mass content of the insulating material may also be related to the value of the thickness T1 of the first insulating structure 42.

[0138] For example, based on the total weight of the first insulating structure 42, the mass content of the adhesive ranges from [10%, 20%], and the thickness T1 of the first insulating structure 42 ranges from [25μm, 50μm].

[0139] For example, based on the total weight of the first insulating structure 42, the mass content of the adhesive ranges from [20%, 40%], and the thickness T1 of the first insulating structure 42 ranges from [50μm, 95μm].

[0140] When the adhesive content is relatively low, the thickness T1 of the first insulating structure 42 should not be set too large, so as to maintain good structural strength of the first insulating structure 42 under relatively low adhesive force, thereby improving its insulation performance. Conversely, when the adhesive content is relatively high, the thickness T1 of the first insulating structure 42 is also larger to improve adhesive force, so that the thicker first insulating structure 42 can also have good structural strength, thereby improving its insulation performance. Therefore, the adhesive content in the material of the first insulating structure 42 can be reasonably set according to different application scenarios, such as according to different requirements for the thickness T1 of the first insulating structure 42.

[0141] It should be understood that the first insulating structure 42 in this embodiment is located in the first edge region 4112 of the first surface 4110 of the negative current collector 41, and the position of the positive electrode 30 may be related to the position of the first insulating structure 42.

[0142] In some embodiments, the positive electrode 30 includes a positive current collector 31 and a positive electrode film 32 disposed on at least one side of the positive current collector 31, and the orthogonal projection of the positive electrode film 32 along the thickness direction of the negative electrode 40 lies within the range of the orthogonal projection of the intermediate region 4111. Figures 7 to 9 As shown, taking the thickness direction of the negative electrode 40 as the thickness direction Y of the battery cell 20 as an example, when the orthogonal projection of the positive electrode film 32 is within the range of the orthogonal projection of the middle region 4111, the length L2 of the metal deposition layer 43 in the middle region 4111 along the height direction Z of the battery cell 20 is greater than or equal to the length L1 of the positive electrode film 32, so that the positive electrode film 32 is set to correspond to the metal deposition layer 43 in the middle region 4111. This can reduce the metal deposited in the area close to the first edge region 4112 and reduce the risk of metal overflowing from the first edge region 4112.

[0143] In some embodiments, along the thickness direction of the negative electrode 40, the orthogonal projection of the positive electrode film 32 is located within the range of the orthogonal projection of the positive electrode current collector 31, that is, the area of ​​the positive electrode current collector 31 is larger than the area of ​​the positive electrode film 32, so that if there is a slight misalignment between the positive electrode 30 and the negative electrode 40 during the processing and assembly of the electrode assembly 22, the risk of edge metal overflow of the negative electrode 40 can be reduced.

[0144] In some embodiments, along the width direction of the positive electrode 30, for example, taking the width direction of the positive electrode 30 as the height direction Z of the battery cell 20, the positive current collector 31 includes a positive electrode body 311 and a positive electrode tab 312. The positive electrode tab 312 protrudes from the positive electrode body 311, and the positive electrode body 311 forms the main body 221 of the electrode assembly 22. Figure 7 As shown, the surface of the positive electrode body 311 is used to form a positive electrode film layer 32. A third insulating structure 33 is also provided on the edge of the positive electrode body 311 near the positive electrode tab 312. The third insulating structure 33 is located on the side of the positive electrode film layer 32 facing the positive electrode tab 312. Furthermore, along the width direction of the positive electrode sheet 30, the positive electrode tab 312 of the positive current collector 31 protrudes from the third insulating structure 33. The third insulating structure 33 is used to isolate the positive current collector 31. For example, the third insulating structure 33 is at least used to isolate the portion of the positive current collector 31 that does not cover the positive electrode film layer 32 and corresponds to the metal deposition layer 43 of the negative electrode sheet 40, so as to reduce the risk of short circuit between the positive electrode sheet 30 and the negative electrode sheet 40.

[0145] Figure 10 Another cross-sectional schematic diagram of the electrode assembly 22 according to an embodiment of this application is shown, wherein, Figure 10 Only a partial cross-sectional schematic diagram of the electrode assembly 22 is shown. Figure 10 The cross-section shown is perpendicular to, as Figures 4 to 6 The cross-section shown, for example, Figures 4 to 6 The cross-section shown is taken as an example in the height direction Z, which is perpendicular to the battery cell 20. Figure 10 The cross-section shown is taken as an example with the length direction X perpendicular to the battery cell 20.

[0146] In some embodiments, along the thickness direction of the negative electrode sheet 40, the negative electrode sheet 40 includes two opposing first surfaces 4110. For example... Figure 10 As shown, taking the thickness direction of the negative electrode 40 as the thickness direction Y of the battery cell 20 as an example, for the case where at least a portion of the negative electrode 40 is sandwiched between two positive electrode 30s, for example, as... Figure 4 and Figure 5 A local area in the negative electrode plate 40 shown, or as Figure 6Among the plurality of negative electrode plates 40 shown, some negative electrode plates 40 may include two first surfaces 4110 provided with a first insulating structure 42. The two first surfaces 4110 are arranged opposite each other along the thickness direction of the negative electrode plate 40, so that the surface of the negative electrode plate 40 facing the positive electrode plate 30 is provided with the first insulating structure 42, so as to prevent metal from overflowing from the corresponding first edge region 4112 through the first insulating structure 42.

[0147] In some embodiments, the electrode assembly 22 of this application further includes a separator 50 located between the positive electrode 30 and the negative electrode 40 to isolate the positive electrode 30 and the negative electrode 40. In some embodiments, the separator 50 is a solid electrolyte. The solid electrolyte is disposed between the positive electrode 30 and the negative electrode 40, serving both to transport ions and to isolate the positive electrode 30 and the negative electrode 40.

[0148] This application does not impose any particular restrictions on the type of separator 50; any porous separator with good chemical and mechanical stability can be selected.

[0149] It should be understood that the material of the isolation membrane 50 in this application embodiment can be selected according to the actual application.

[0150] As an example, the main material of the separator 50 can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator 50 can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator 50 is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator 50 can be a single component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be applied to the surface of the separator 50.

[0151] In some embodiments, the separator 50 has a multilayer structure, and the porosity of the structural layer of the separator 50 facing the negative electrode 40 is greater than or equal to 70% to enhance the wettability between the electrolyte and the electrode, and also to improve the ion transport efficiency, thereby improving the performance of the electrode assembly 22.

[0152] It should be understood that the size of the separator 50 in this embodiment can be set according to actual application. For example, the thickness of the separator 50 can be determined according to the thickness of the metal deposition layer 43. For example, taking the separator 50 as a double-layer structure, the thickness of the layer structure of the separator 50 near the negative electrode 40 is usually approximately the thickness T2 of the metal deposition layer 43 divided by 0.8. This can improve ion transport efficiency to improve the performance of the battery cell 20, and also limit the space occupied by the separator 50 to improve the energy density of the battery cell 20.

[0153] The electrode assembly 22 of the present application will now be described in conjunction with specific embodiments and comparative examples.

[0154] In the following embodiments and comparative examples, battery cell 20 is used as an example. Figure 3 Taking the square-shell battery shown as an example, the preparation methods of the positive electrode 30, negative electrode 40, electrolyte and separator 50 of the electrode assembly 22 of the battery cell 20 are as follows.

[0155] 1. Preparation of positive electrode 30

[0156] The positive electrode active material sodium iron pyrophosphate, the conductive agent carbon nanotubes, and the binder metahexafluorophosphate were thoroughly mixed in N-methylpyrrolidone (NMP) at a mass ratio of 95:2:3 to form a uniform positive electrode slurry. The positive electrode slurry was coated on the surface of the positive electrode current collector 31 aluminum foil, and after drying, cold pressing, and die cutting, a positive electrode sheet 30 with a thickness of 200 μm was obtained.

[0157] 2. Preparation of negative electrode sheet 40

[0158] Alumina and polyacrylic acid (PAA) were thoroughly mixed in an appropriate amount of deionized water at a weight ratio of 70:30 to form an insulating coating slurry. The alumina had a volumetric particle size distribution (Dv50) of 0.25 μm and a tap density of 1.38 g / cm³. 3 The specific surface area is 13.4 m². 2 / g.

[0159] 10 wt% conductive carbon black and an appropriate amount of deionized water are mixed to form a slurry, and then a conductive coating with a thickness of 2 μm is formed on the surface of copper foil by extrusion coating.

[0160] In the width direction of the negative electrode current collector, an insulating coating slurry is applied to both sides of the conductive layer slurry to form a first insulating structure 42. After drying, cold pressing, and welding of the negative electrode tabs 412, a negative electrode sheet 40 is obtained.

[0161] 3. Preparation of the separating membrane 50

[0162] The separator 50 is a composite separator, consisting of a 7µm polyethylene (PE) film and a frame layer. Specifically, inorganic alumina particles and polyvinylidene fluoride binder are mixed at a mass ratio of 90:10 to obtain a slurry. The slurry is sprayed onto both sides of the 7µm PE substrate, dried to obtain a base film layer, and the frame layer is bonded to the base film layer. The composite base film is then rolled to obtain the separator 50.

[0163] 4. Preparation of electrolyte (types and formulations of solvents, lithium salts, and additives):

[0164] In an argon-filled glove box with a water content of <1ppm, diethylene glycol dimethyl ether and tetrahydrofuran were mixed at a mass ratio of 1:3, and sodium hexafluorophosphate (NaPF6) with a concentration of 1.0mol / L was added. After stirring evenly, an electrolyte was obtained.

[0165] 5. Preparation of battery cell 20

[0166] Multiple positive electrode plates 30, separator membranes 50, and multiple negative electrode plates 40 are stacked in sequence, with the separator membrane 50 positioned between the positive electrode plates 30 and the negative electrode plates 40 to isolate the positive and negative electrodes. This stacking process yields the desired result. Figure 6 The bare cell shown is welded with tabs, placed inside the casing 21, and the electrolyte prepared above is injected into the dried casing. The process includes encapsulation, settling, formation, shaping, and capacity testing to complete the preparation of the battery cell 20.

[0167] Battery cell 20 is obtained according to the above preparation method. Battery cell 20 also satisfies the conditions in Table 1 below, wherein the thickness of the first insulating structure 42 of the negative electrode 40 of battery cell 20 is T1, and the thickness of the metal deposition layer 43 is T2. In Examples 1-3, the thickness T1 of the first insulating structure 42 is set to 32 μm as an example. The different values ​​of the thickness T2 of the metal deposition layer 43 in various examples and comparative examples can be obtained by adjusting the single-sided areal density of the positive electrode 30. For example, the single-sided areal density of the positive electrode 30 can be set to approximately 430 g / 1540.25 mm. 2 This corresponds to a metal deposition layer 43 thickness T2 of 25 μm; by setting the single-sided areal density of the positive electrode 30 to approximately 600 g / 1540.25 mm. 2 This corresponds to a metal deposition layer 43 thickness T2 of 32 μm; by setting the single-sided areal density of the positive electrode 30 to approximately 800 g / 1540.25 mm. 2 The corresponding thickness T2 of the metal deposition layer 43 is 45 μm.

[0168] For the battery cell 20 of each embodiment and comparative example in Table 1, the battery cell 20 is charged at room temperature at a rate of 0.33C to a voltage of 3.65V to obtain the charging capacity C1; then it is discharged at a rate of 0.33C to a voltage of 1.5V to obtain the reversible capacity C2; the "first formation efficiency" in Table 1 is the value of C2 / C1.

[0169] Table 1

[0170] Example 1 32 25 93.8 Example 2 32 32 92 Example 3 32 45 91 Comparative Example 1 / 45 85

[0171] As shown in Table 1, when the negative electrode 40 of the battery cell 20 is provided with a first insulating structure 42, the first formation efficiency of the battery cell 20 can be improved, for example, it can reach more than 90%. However, without the first insulating structure 42, the first formation efficiency cannot meet the requirement of 90%.

[0172] In this embodiment of the application, the battery cell 20 is also used as an example. Figure 3 Taking the square-shell battery shown as an example, the positive electrode 30, negative electrode 40, electrolyte and separator 50 of the battery cell 20 are prepared in the same manner as described above, thereby obtaining the various embodiments shown in Table 2.

[0173] Specifically, in the embodiments shown in Table 2 below, for embodiments 4-7, all settings are the same except for the parameter settings shown in Table 2. The thickness of the first insulating structure 42 on the negative electrode 40 of the battery cell 20 is T1, which corresponds to the thickness of the first insulating structure 42 coated in the embodiments in Table 2 below; the thickness of the metal deposition layer 43 is T2; and the single-sided areal density of the positive electrode 30 is M, where M is 400g / 1540.25mm² in all embodiments in Table 2 below. 2 For example, the corresponding thickness T2 is 23μm; the width of the first insulating structure 42 is W1, that is, in the first direction of the negative electrode sheet 40 in each embodiment of Table 2 below, the width of the first insulating structure 42 coated is W1.

[0174] For each embodiment in Table 2, the battery cell 20 was charged at room temperature at a rate of 0.33C to a voltage of 3.65V, and the constant voltage charging capacity Cv and the total capacity C0 were recorded. If the measured Cv / C0 ratio is greater than 1%, it indicates that the battery cell 20 has experienced an internal short circuit; otherwise, it indicates that no internal short circuit has occurred. In Table 2, "internal short circuit" indicates whether the test result indicates whether the battery cell 20 has experienced an internal short circuit.

[0175] Battery cell 20 was charged at room temperature at a rate of 0.33C to a voltage of 3.65V, and then discharged at a rate of 0.33C to a voltage of 1.5V. The reversible capacity was measured as C. This charging and discharging process was repeated until the discharge capacity Cn of battery cell 20 satisfied Cn / C≤80%. The total number of cycles n was recorded. Here, Cn is the reversible capacity at the nth cycle. The "Number of Cycles" in Table 2 below represents the recorded number of cycles n.

[0176] Table 2

[0177] Example 4 24 23 400 1.5 no 2150 Example 5 25 23 400 1.5 no 2350 Example 6 28 23 400 1.5 no 2850 Example 7 31 23 400 1.5 no 2750 Example 8 31 23 400 1 no 2530 Example 9 31 23 400 3 no 2790

[0178] As shown in Table 2 above, by setting the thickness T1 of the first insulating structure 42 to be greater than the thickness T2 of the metal deposition layer 43, the risk of internal short circuits in the battery cell 20 can be effectively reduced, and the cycle life of the battery cell 20 can be increased, for example, the cycle life of the battery cell 20 can reach more than 2000. Especially when the difference between the thickness T1 of the first insulating structure 42 and the thickness T2 of the metal deposition layer 43 is in the range of [2μm, 8μm], the cycle life of the battery cell 20 can be significantly increased. Specifically, when the difference between the thickness T1 of the first insulating structure 42 and the thickness T2 of the metal deposition layer 43 is about 5μm, the cycle life of the battery cell 20 is relatively high. In addition, increasing the width W1 of the first insulating structure 42 can also effectively increase the cycle life of the battery cell 20.

[0179] According to some embodiments of this application, this application also provides a battery device including a battery cell 20 as described in any of the above embodiments.

[0180] 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.

[0181] The electrical equipment can be any of the aforementioned devices or systems that utilize the battery device 10.

[0182] According to some embodiments of this application, see Figures 7 to 10This application provides a battery cell 20, which includes an electrode assembly 22. The electrode assembly 22 includes a positive electrode 30 and a negative electrode 40. The negative electrode 40 includes a negative current collector 41, which includes a negative electrode body 411 and a negative electrode tab 412. The first surface 4110 of the negative electrode body 411 includes a central region 4111 and two first edge regions 4112. Along a first direction, the central region 4111 is located between the two first edge regions 4112, and the negative electrode tab 412 extends from the first edge regions 4112 of the negative electrode body 411. The central region 4111 has a metal deposition layer 43. The two first edge regions 4112 are respectively provided with a first insulating structure 42, and the thickness of the first insulating structure 42 is greater than the thickness of the metal deposition layer 43. Along the first direction, the width of the first insulating structure 42 ranges from [0.1 mm to 3 mm].

[0183] The single-sided areal density of the positive electrode 30 ranges from [400g / 1540.25mm]. 2 1500g / 1540.25mm 2 The thickness of the metal deposition layer 43 ranges from [20μm to 90μm], and the thickness of the first insulating structure 42 ranges from [25μm to 95μm].

[0184] The first insulating structure 42 includes an insulating material that satisfies at least one of the following conditions: the volume distribution particle size Dv50 of the insulating material is less than or equal to 2 μm; the tap density of the insulating material is in the range of [0.8 g / cm³]. 3 2.0g / cm 3 ]; and the specific surface area of ​​the insulating material ranges from [3m 2 / g, 25m 2 The first insulating structure 42 includes an adhesive, and based on the total weight of the first insulating structure 42, the mass of the adhesive ranges from [10%, 20%], and the thickness of the first insulating structure 42 ranges from [25μm, 50μm]; or, based on the total weight of the first insulating structure 42, the mass content of the adhesive ranges from [20%, 40%], and the thickness of the first insulating structure 42 ranges from [50μm, 95μm].

[0185] The electrode assembly 22 includes multiple positive electrode plates 30 and multiple negative electrode plates 40, which are stacked along the thickness direction of the negative electrode plate 40. The first surface 4110 also includes two second edge regions 4113. Along a second direction, a middle region 4111 is located between the two second edge regions 4113, and the second direction is perpendicular to the first direction. Each of the two second edge regions 4113 is provided with a second insulating structure, the thickness of which is greater than the thickness of the metal deposition layer 43. Along the second direction, the width of the second insulating structure ranges from 0.1 mm to 3 mm.

[0186] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, The battery cell includes an electrode assembly (22), the electrode assembly (22) includes a positive electrode plate (30) and a negative electrode plate (40), the negative electrode plate (40) includes a negative current collector (41), the negative current collector (41) includes a negative electrode body (411) and a negative electrode tab (412), the negative electrode body (411) includes at least one first surface (4110), the first surface (4110) includes a middle region (4111) and two first edge regions (4112); Along the first direction, the intermediate region (4111) is located between the two first edge regions (4112), and the negative electrode tab (412) extends from the first edge region (4112) of the negative electrode body (411). The intermediate region (4111) has a metal deposition layer (43), and at least one of the two first edge regions (4112) is provided with a first insulating structure (42).

2. The battery cell according to claim 1, characterized in that, The two first edge regions (4112) are respectively provided with a first insulating structure (42).

3. The battery cell according to claim 1, characterized in that, The thickness of the first insulating structure (42) is greater than the thickness of the metal deposition layer (43), and the thickness of the metal deposition layer (43) is the same as the thickness of the metal deposition layer (43) when the battery cell is fully charged.

4. The battery cell according to claim 3, characterized in that, The difference between the thickness of the first insulating structure (42) and the thickness of the metal deposition layer (43) ranges from 0 μm to 10 μm.

5. The battery cell according to claim 1, characterized in that, Along the first direction, the width of the first insulating structure (42) ranges from [0.1 mm to 3 mm].

6. The battery cell according to claim 1, characterized in that, The single-sided areal density of the positive electrode sheet (30) ranges from [400g / 1540.25mm]. 2 1500g / 1540.25mm 2 The thickness of the metal deposition layer (43) ranges from [20μm to 90μm], and the thickness of the first insulating structure (42) ranges from [25μm to 95μm].

7. The battery cell according to claim 6, characterized in that, The single-sided areal density of the positive electrode sheet (30) ranges from [600g / 1540.25mm]. 2 800g / 1540.25mm 2 The thickness of the metal deposition layer (43) ranges from [32μm, 46μm], and the thickness of the first insulating structure (42) ranges from [37μm, 51μm].

8. The battery cell according to claim 1, characterized in that, The first insulating structure (42) includes an insulating material that satisfies at least one of the following conditions: The volumetric particle size Dv50 of the insulating material is less than or equal to 2 μm; The tap density of the insulating material ranges from [0.8 g / cm³]. 3 2.0g / cm 3 ];as well as The specific surface area of ​​the insulating material ranges from [3m² to 10m²]. 2 / g, 25m 2 / g).

9. The battery cell according to claim 1, characterized in that, The first insulating structure (42) includes an adhesive. Based on the total weight of the first insulating structure (42), the mass content of the adhesive ranges from [10%, 20%], and the thickness of the first insulating structure (42) ranges from [25μm, 50μm]; or, Based on the total weight of the first insulating structure (42), the mass content of the adhesive ranges from [20%, 40%], and the thickness of the first insulating structure (42) ranges from [50μm, 95μm].

10. The battery cell according to any one of claims 1 to 9, characterized in that, The electrode assembly (22) includes a plurality of positive electrode plates (30) and a plurality of negative electrode plates (40), which are stacked along the thickness direction of the negative electrode plate (40). The first surface (4110) also includes two second edge regions (4113). Along the second direction, the intermediate region (4111) is located between the two second edge regions (4113), and the second direction is perpendicular to the first direction; The two second edge regions (4113) are respectively provided with a second insulating structure.

11. The battery cell according to claim 10, characterized in that, The thickness of the second insulating structure is greater than the thickness of the metal deposition layer (43).

12. The battery cell according to claim 10, characterized in that, Along the second direction, the width of the second insulating structure ranges from [0.1 mm to 3 mm].

13. The battery cell according to any one of claims 1 to 9, characterized in that, The positive electrode (30) and the negative electrode (40) are wound around a winding shaft to form the electrode assembly (22), wherein the direction of the winding shaft is the first direction; or, The electrode assembly (22) includes a plurality of positive electrode plates (30), and the negative electrode plate (40) includes at least one bent segment (401) and a plurality of stacked segments (402) connected to each other. Each bent segment (401) connects two stacked segments (402), and the plurality of stacked segments (402) and the plurality of positive electrode plates (30) are stacked together along the thickness direction of the positive electrode plates (30).

14. The battery cell according to any one of claims 1 to 9, characterized in that, The positive electrode (30) includes a positive current collector (31) and a positive electrode film (32) disposed on at least one side of the positive current collector (31). Along the thickness direction of the negative electrode (40), the orthogonal projection of the positive electrode film (32) is located within the range of the orthogonal projection of the intermediate region (4111).

15. A battery device, characterized in that, include: Multiple battery cells, wherein the battery cells are battery cells as described in any one of claims 1 to 14.

16. An electrical appliance, characterized in that, include: A battery device comprising a battery cell as claimed in any one of claims 1 to 14, the battery device being used to supply power to the electrical device.

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