Electrode assembly, battery cell, battery and power consuming device

Abstract

The present invention provides an electrode assembly (100), a battery cell (200), a battery (300), and a power consumption device (400), wherein the electrode assembly (100) includes a positive electrode plate (10) and a negative electrode current collector (20) stacked along a first direction, and at least one of the positive electrode plate (10) and the negative electrode current collector (20) includes a substrate assembly (30) having a substrate layer (31) and an elastic layer (32), and the substrate layer (31) and the corresponding elastic layer (32) are stacked along the first direction.

Description

[Technical Field]

[0001] The present application relates to the field of batteries, and in particular to electrode assemblies, battery cells, batteries and power consuming devices. [Background technology]

[0002] In the related art, a battery cell includes a case and an electrode assembly, and the electrode assembly is installed in the case. During the process of charging the battery, metal (e.g., lithium, sodium, potassium) deposition occurs on the negative electrode current collector, causing the volume of the electrode assembly to expand and the volume change rate of the electrode assembly to increase. When the electrode assembly expands, a large stress is applied to the case, which may lead to the explosion of the battery cell, affecting the service life of the battery cell, and reducing the safety of using the battery cell. Summary of the Invention [Problem to be solved by the invention]

[0003] The present application aims to solve at least one of the technical problems existing in the prior art, and therefore, an object of the present application is to provide an electrode assembly in which an elastic layer of the electrode assembly can be compressed during the process of charging a battery, absorbing and mitigating the volume expansion of the electrode assembly, reducing the force applied to the battery cell case, reducing the risk of the battery cell exploding, and improving the service life and safety of the battery cell. [Means for solving the problem]

[0004] The present application further provides a battery cell.

[0005] The present application further provides a battery.

[0006] The present application further provides a power consuming device.

[0007] According to a first aspect, an embodiment of the present application provides an electrode assembly, comprising a positive electrode plate and a negative electrode current collector stacked along a first direction, at least one of the positive electrode plate and the negative electrode current collector comprising a substrate assembly having a substrate layer and an elastic layer, the substrate layer and the corresponding elastic layer being stacked along the first direction.

[0008] In the above technical solution, by providing an elastic layer, the elastic layer can be compressed during the process of charging the battery, absorbing and mitigating the volume expansion of the electrode assembly. The elastic layer absorbs the expansion force of the electrode assembly, reducing the force applied to the battery cell casing, reducing the risk of the battery cell exploding, and improving the service life and safety of the battery cell.

[0009] In some embodiments, an elastic layer is provided on at least one side of the base layer along the first direction.

[0010] In the above technical solution, an elastic layer is provided on at least one side of the substrate layer. When the positive electrode plate and the negative electrode current collector are stacked along a first direction, the elastic layer can be positioned between the positive electrode plate and the substrate layer. During charging of the battery cell, the elastic layer can be compressed, and the elastic layer can absorb and mitigate the volume expansion of the electrode assembly, thereby reducing the stress caused by the volume expansion of the electrode assembly.

[0011] In some embodiments, the substrate assembly includes a plurality of substrate layers stacked along a first direction, with an elastic layer disposed between at least two adjacent substrate layers.

[0012] In the above technical solution, an elastic layer is provided between two adjacent substrate layers, so that during charging of the battery cell, a metal ion (e.g., sodium ion) layer is deposited on the surface of the substrate layer away from the elastic layer. After the metal ions are deposited on the surface of the substrate layer, the elastic layer is compressed by the expansion force, and the elastic layer can absorb and mitigate the volume expansion of the electrode assembly, thereby reducing the stress caused by the volume expansion of the electrode assembly.

[0013] In some embodiments, the elastic layer is connected to an adjacent substrate layer.

[0014] In the above technical solution, the elastic layer is connected to the substrate layer, so that the elastic layer and the substrate layer are fixedly attached, reducing the risk of misalignment between the elastic layer and the substrate layer, and the elastic layer can be securely attached between the substrate layer and the positive electrode plate. During the charging process of the battery cell, after metal ions are deposited on the surface of the negative electrode current collector, the elastic layer is compressed in the first direction due to the expansion force, and the elastic layer can absorb and mitigate the volume expansion of the electrode assembly.

[0015] In some embodiments, the elastic layer is adhesively secured to the adjacent substrate layer.

[0016] In the above technical proposal, the elastic layer is adhered and fixed to the adjacent base layer, thereby reliably fixing the elastic layer and the base layer, reducing the risk of the elastic layer and the base layer separating and reducing the risk of misalignment between the elastic layer and the base layer. Furthermore, the elastic layer is adhered and fixed to the base layer, which simplifies the process of attaching the elastic layer and the base layer and improves the efficiency of attaching the elastic layer and the base layer.

[0017] In some embodiments, along a first direction, the substrate layer has a first side and the elastic layer has a second side, the first side abutting a corresponding second side.

[0018] In the above technical solution, the first side of the substrate layer abuts against the second side of the elastic layer, so that during charging of the battery cell, metal ions (e.g., sodium ions) are deposited on the surface of the negative electrode current collector, and the expansion force is transmitted to the elastic layer, causing the elastic layer to compress. The elastic layer can absorb and mitigate the volume expansion of the electrode assembly, thereby reducing the stress caused by the volume expansion of the electrode assembly.

[0019] In some embodiments, both the first side and the second side are configured as planar surfaces.

[0020] In the above technical solution, by making both the first side and the second side flat, the first side and the second side can be made more flat, and after the elastic layer and the base layer are attached, the contact area between the first side and the second side can be increased, and the first side and the second side can be reliably contacted. During the process of charging the battery cell, after metal ions (e.g., sodium ions) are deposited on the surface of the negative electrode current collector, the force applied to the elastic layer can be made uniform, the elastic layer can be compressed more uniformly, and the risk of stress concentration in the elastic layer can be reduced.

[0021] In some embodiments, along the first direction, an orthogonal projection of the substrate layer lies within an orthogonal projection of the elastic layer.

[0022] In the above technical solution, the orthogonal projection of the substrate layer is located within the orthogonal projection of the elastic layer. Therefore, during charging of the battery cell, after metal ions (e.g., sodium ions) are deposited on the surface of the negative electrode current collector, the elastic layer can be compressed, and the expansion force can be transmitted to the elastic layer. The elastic layer can absorb and mitigate the volume expansion of the electrode assembly, thereby reducing the stress caused by the volume expansion of the electrode assembly.

[0023] In some embodiments, the exterior surface of the negative electrode current collector has a layer of negative electrode active material.

[0024] In the above technical solution, a negative electrode plate can be formed by providing a negative electrode active material layer on the outer surface of a negative electrode current collector, and a battery cell can have a positive electrode plate and a negative electrode plate.

[0025] In some embodiments, the elastic layer is a high molecular weight polymer.

[0026] In the above technical solution, the elastic layer is made of a high molecular weight polymer, which can improve the temperature resistance, adhesive strength, and corrosion resistance of the elastic layer, thereby improving the performance of the battery cell.

[0027] In some embodiments, the thickness of the substrate layer is between 5% and 80% of the total thickness of the substrate assembly, and the thickness of the elastic layer is between 20% and 95% of the total thickness of the substrate assembly.

[0028] The above technical solution reduces the space occupied by the elastic layer in the initial uncompressed state, thereby reducing the risk of affecting the space of the electrode assembly and causing a loss of energy density, while also ensuring the space occupied by the elastic layer and increasing the compressible space of the elastic layer, thereby effectively absorbing the expansion of the electrode assembly.

[0029] In some embodiments, the initial thickness of the elastic layer is D1 and the compressed thickness of the elastic layer is D2, satisfying the relationship 0.1≦1−D2 / D1≦0.95.

[0030] In the above technical solution, the elastic layer has sufficient compressibility, and the elastic layer can be compressed and deformed as the electrode assembly expands, and can absorb the expansion of the electrode assembly. At the same time, processing problems caused by excessively large compressibility, such as deformation and rebound during the production of the electrode assembly, are reduced.

[0031] In some embodiments, the elastic layer has a hollowed-out structure.

[0032] In the above technical solution, by providing a hollowed-out structure in the elastic layer, the weight of the elastic layer can be reduced, which in turn reduces the weight of the electrode assembly, thereby reducing the weight of the battery cell, which is advantageous for achieving a lightweight design of the battery cell.

[0033] In some embodiments, the lightening structures are lightening holes and / or lightening grooves.

[0034] In the above technical proposal, by providing the cutout structure as a cutout hole and / or a cutout groove, the structure of the cutout structure can be simplified, and the cutout structure can be easily provided in the elastic layer, thereby simplifying the elastic layer structure.

[0035] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode plate and the negative electrode current collector to separate the positive electrode plate and the negative electrode current collector.

[0036] In the above technical solution, a separator is placed between the positive electrode plate and the negative electrode current collector, so that the separator separates the positive electrode plate and the negative electrode current collector, preventing short circuits caused by contact between the positive electrode plate and the negative electrode current collector, and improving the safety of the battery cell.

[0037] In some embodiments, the separator has, in the thickness direction of the separator, a positive electrode end located near the positive electrode plate and having a plurality of first apertures, and a negative electrode end located near the negative electrode current collector and having a plurality of second apertures, the aperture diameter of the first apertures being larger than the aperture diameter of the second apertures.

[0038] In the above technical solution, the separator of the present application can solve the problems of battery capacity loss and safety caused by the volume expansion of the negative electrode current collector during the battery cycling process.

[0039] In some embodiments, the diameter of the first pores is 20 nm to 1000 μm, preferably 50 nm to 500 μm.

[0040] The above technical solution can improve the liquid retention effect of the negative electrode end of the separator and increase its density, thereby resolving the problems of battery capacity loss and safety caused by the volume expansion of the negative electrode current collector during battery cycling.

[0041] In some embodiments, the diameter of the second pores is 20 nm to 500 μm, preferably 50 nm to 100 μm.

[0042] The above technical solution can improve the liquid retention effect of the negative electrode end of the separator and increase its density, thereby resolving the problems of battery capacity loss and safety caused by the volume expansion of the negative electrode current collector during battery cycling.

[0043] In some embodiments, the pore size of the separator pores increases in the direction from the negative electrode end to the positive electrode end.

[0044] The above technical solution can adjust the concentration gradient of metal ion diffusion during the charging process of the battery, so that the metal ions are uniformly deposited on the surface of the negative electrode current collector, reducing the occurrence of metal dendrites and the volume expansion of the negative electrode current collector.

[0045] In some embodiments, the separator includes a capillary structure disposed along its height, with one end flush with the bottom edge of the separator.

[0046] In the above technical solution, when the volume of the negative electrode current collector expands and presses against the separator, the siphon effect of the capillary allows the electrolyte at the bottom of the battery cell to be siphoned up into the separator, quickly replenishing the shortage of electrolyte in the height direction of the separator.

[0047] In some embodiments, the length of the capillary structure H1 > 70% H2, where H2 is the height of the separator.

[0048] The above technical solution can quickly replenish the electrolyte insufficiency in the height direction of the separator.

[0049] In some embodiments, the separator has a compressive modulus of 5% to 95%.

[0050] The above technical solution can reduce the swelling of the battery cell caused by the volume expansion of the negative electrode current collector, and improve the safety performance of the battery cell.

[0051] In some embodiments, the separator is a sponge-based film.

[0052] The above technical solution can improve the liquid retention effect and reduce the capacity loss of the battery cell.

[0053] In some embodiments, the separator includes a sponge base film and a coating layer formed on at least one side of the sponge base film, and the capillary structure is provided on the sponge base film.

[0054] The above technical solution can improve the liquid retention effect and strength of the separator, and solve the problems of capacity loss and safety of the battery cell caused by the volume expansion of the negative electrode current collector during the battery cycling process.

[0055] In some embodiments, the sponge-based film comprises at least one of glass fiber, nanofiber, polyethylene, polypropylene, and nonwoven fabric.

[0056] The above technical solution can improve the liquid retention effect and reduce the capacity loss of the battery cell.

[0057] In some embodiments, the coating layer is formed on one side of the sponge base film, the second aperture is provided in the coating layer, and the first aperture is provided at an end of the sponge base film away from the coating layer.

[0058] The above technical solution can improve the liquid retention effect and strength of the separator, and solve the problems of capacity loss and safety of the battery cell caused by the volume expansion of the negative electrode current collector during the cycle process of the battery cell.

[0059] In some embodiments, the coating layers are formed on both sides of the sponge base film, the second aperture is provided in the coating layer located at the negative electrode end, and the first aperture is provided in the coating layer located at the positive electrode end.

[0060] The above technical solution can improve the liquid retention effect and strength of the separator, and solve the problems of capacity loss and safety of the battery cell caused by the volume expansion of the negative electrode current collector during the cycle process of the battery cell.

[0061] In some embodiments, the separator includes a first separation membrane, an intermediate separation membrane, and a second separation membrane stacked along its thickness direction, and the first aperture is provided in the first separation membrane and the second aperture is provided in the second separation membrane.

[0062] In some embodiments, the pore size of the intermediate separation membrane is larger than the pore size of the first aperture or the pore size of the second aperture, and / or the porosity of the intermediate separation membrane is larger than the porosity of the first separation membrane or the second separation membrane.

[0063] The above technical solution can improve the liquid retention effect of the separator and reduce the capacity loss of the battery cell.

[0064] In some embodiments, the first separation membrane, the intermediate separation membrane, and the second separation membrane satisfy at least one of the following conditions: the porosity of the first separation membrane is 30% to 70%, the pore size of the intermediate separation membrane is 30 nm to 1 μm, the porosity of the intermediate separation membrane is 40% to 90%, and the porosity of the second separation membrane is 30% to 70%.

[0065] The above technical solution can improve the liquid retention effect of the separator and reduce the capacity loss of the battery cell.

[0066] According to a second aspect, an embodiment of the present application further provides a battery cell including the electrode assembly described above.

[0067] According to a third aspect, embodiments of the present application further provide a battery including the battery cell described above.

[0068] According to a fourth aspect, embodiments of the present application further provide a power consuming device including the battery described above.

[0069] Additional aspects and advantages of the present application will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the present application. [Brief explanation of the drawings]

[0070] [Figure 1] 1 is a structural schematic diagram of a power consumption device according to an embodiment of the present application; [Figure 2] 1 is a structural schematic diagram of a battery according to an embodiment of the present application. [Figure 3] 1 is a structural schematic diagram of a battery cell according to an embodiment of the present application. [Figure 4] 1 is a structural schematic diagram of an electrode assembly according to some embodiments of the present application. [Figure 5] 1 is a structural schematic diagram of an electrode assembly according to some embodiments of the present application. [Figure 6] 1 is a structural schematic diagram of a substrate assembly according to some embodiments of the present application. [Figure 7] 1 is a structural schematic diagram of a substrate assembly according to some embodiments of the present application. [Figure 8] 1 is a structural schematic diagram of a negative electrode current collector according to some embodiments of the present application, in which a negative electrode active material layer is provided on the outer surface thereof; [Figure 9] 1 is a structural schematic diagram of a separator according to an embodiment of the present invention; [Figure 10] FIG. 2 is a structural schematic diagram of a separator according to another embodiment of the present invention. [Figure 11] FIG. 4 is a structural schematic diagram of a separator according to still another embodiment of the present application. [Figure 12] FIG. 4 is a structural schematic diagram of a separator according to still another embodiment of the present application. [Figure 13] FIG. 4 is a structural schematic diagram of a separator according to still another embodiment of the present application. [Figure 14] FIG. 4 is a structural schematic diagram of a separator according to still another embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0071] In order to clarify the objectives, technical solutions and advantages of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without any creative efforts fall within the scope of protection of the present application.

[0072] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Terms used in the specification of the present application are merely for the purpose of describing specific embodiments and are not intended to limit the present application. The terms "comprise," "have," and any variations thereof in the specification, claims, and drawings of the present application are intended to cover a non-exclusive "inclusive" meaning. Terms such as "first," "second," and the like in the specification, claims, and drawings of the present application are intended to distinguish between different objects and are not intended to describe a specific order or a hierarchy.

[0073] In this application, when a reference is made to an "embodiment," it means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment of other embodiments.

[0074] In the description of this application, unless otherwise clearly specified or limited, the terms "attach," "connect," "connection," and "attachment" should be understood in a broad sense, and may refer to, for example, a fixed connection, a detachable connection, an integral connection, a direct connection, an indirect connection via an intervening object, or internal communication between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application according to specific circumstances.

[0075] In this application, the term "and / or" merely describes the relationship between related objects and indicates three possible relationships, for example, A and / or B can indicate three cases: only A exists, both A and B exist, and only B exists. Also, in this application, the character " / " generally indicates that the related objects before and after it are in an "or" relationship.

[0076] In the embodiments of the present application, the same reference numerals refer to the same elements, and for the sake of brevity, detailed descriptions of the same elements will be omitted in different embodiments. It should be understood that the dimensions such as thickness, length, width, etc. of various elements in the embodiments of the present application shown in the drawings, and the dimensions such as thickness, length, width, etc. of the entire integrated device are merely illustrative and do not constitute any limitations on the present application.

[0077] The term "plurality" as used herein refers to two or more (including two).

[0078] In this application, the battery cells may include lithium ion secondary batteries, lithium ion primary batteries, lithium-sulfur batteries, sodium lithium ion batteries, sodium ion batteries, magnesium ion batteries, etc., but the embodiments of this application are not limited thereto. The battery cells may be cylindrical, flat, rectangular, or have other shapes, but the embodiments of this application are not limited thereto. Battery cells are generally divided into three types based on the packaging method: prismatic battery cells, rectangular battery cells, and pouch battery cells, but the embodiments of this application are not limited thereto.

[0079] The term "battery" as used herein refers to a single physical module containing one or more battery cells to provide higher voltage and capacity. For example, the term "battery" may include a battery module or a battery pack. A battery generally includes a housing for packaging one or more battery cells or multiple battery modules. The housing can prevent liquids or other foreign objects from affecting the charging and discharging of the battery cells.

[0080] A battery cell includes a case, an electrode assembly, and an electrolyte. The case is used to accommodate the electrode assembly and the electrolyte. The electrode assembly is composed of a positive electrode plate, a negative electrode plate, and a separator. The battery cell operates primarily through the movement of metal ions between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode current collector. The positive electrode current collector without the positive electrode active material layer protrudes from the positive electrode current collector already coated with the positive electrode active material layer, and the positive electrode current collector without the positive electrode active material layer is called a positive electrode tab. For example, in a lithium-ion battery, the positive electrode current collector may be made of aluminum, and the positive electrode active material may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, lithium manganese oxide, or the like. The negative electrode plate includes a negative electrode current collector, or a negative electrode plate includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer being coated on the surface of the negative electrode current collector, the negative electrode current collector not coated with the negative electrode active material layer protruding from the negative electrode current collector already coated with the negative electrode active material layer, and the negative electrode current collector not coated with the negative electrode active material layer is called a negative electrode tab. The material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon or silicon, etc. To ensure that they do not melt even when a large current flows, the positive electrode tabs are multiple and stacked, and the negative electrode tabs are multiple and stacked.

[0081] The separator may be made of a material such as PP (polypropylene) or PE (polyethylene). The electrode assembly may have a wound structure or a stacked structure, and the embodiments of the present application are not limited thereto.

[0082] The inventors have found that during the process of charging a battery, metal (e.g., lithium, sodium, potassium) deposition occurs on the negative electrode current collector, causing the volume of the electrode assembly to expand and the volume change rate of the electrode assembly to increase. When the electrode assembly expands, the stress on the battery cell case increases, leading to the explosion of the battery cell, which affects the service life of the battery cell and reduces the safety of using the battery cell.

[0083] Based on the above considerations, in order to solve the problem of large stress on the battery cell case caused by the expansion of the electrode assembly, the inventors conducted extensive research and designed an electrode assembly, which is provided with an elastic layer. The elastic layer can be compressed during the battery charging process to absorb and mitigate the volumetric expansion of the electrode assembly. The elastic layer absorbs the expansion force of the electrode assembly, reducing the force on the battery cell case, reducing the risk of the battery cell exploding, and improving the service life and safety of the battery cell.

[0084] The batteries disclosed in the embodiments of the present application can be used in power consumption devices such as, but not limited to, vehicles, ships, and spacecraft, etc. The battery thermal management system and batteries disclosed in the present application can be used to configure a power supply system for the power consumption device, which is advantageous in expanding the scope of application of the battery thermal management system and reducing the difficulty of installing the battery thermal management system.

[0085] An embodiment of the present application provides a battery-powered power consumption device, which may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a steamship, a spacecraft, etc. Here, the electric toy may include a stationary or mobile electric toy, such as a game console, an electric car toy, an electric steamship toy, and an electric airplane toy, and the spacecraft may include an airplane, a rocket, a space shuttle, a spaceship, etc.

[0086] In the following embodiment, for convenience, the power consumption device of one embodiment of the present application is a vehicle.

[0087] Referring to FIG. 1, FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application. The vehicle may be a fuel oil vehicle, a gas vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, a range-extender vehicle, etc. A battery 300 is provided inside the vehicle, and may be provided at the bottom, front, or rear of the vehicle. The battery 300 may be used to power the vehicle, for example, as an operating power source for the vehicle. The vehicle may further include a controller 401 and a motor 402, and the controller 401 is used to control the battery 300 to power the motor 402, for example, for vehicle startup, navigation, and operating power consumption needs during driving.

[0088] In some embodiments of the present application, the battery 300 can provide not only the vehicle's operating power source, but also the vehicle's drive power source, providing drive power to the vehicle in place of, or in place of, fuel oil or natural gas.

[0089] 2, which is an exploded view of a battery 300 according to some embodiments of the present disclosure. The battery 300 includes a housing 301 and a plurality of battery cells 200, and the battery cells 200 are accommodated in the housing 301. The housing 301 is used to provide a mounting space for the battery cells 200, and the housing 301 can adopt various structures. In some embodiments, the housing 301 may include a first housing body 302 and a second housing body 303, and the first housing body 302 and the second housing body 303 are engaged with each other, and the first housing body 302, together with the second housing body 303, define a mounting space for accommodating the battery cells 200. The second housing body 303 may have a hollow structure with one end open, and the first housing body 302 may have a plate-like structure, and the first housing body 302 is engaged with the open side of the second housing body 303, and the first housing body 302 defines an installation space together with the second housing body 303. The first housing body 302 and the second housing body 303 may both have a hollow structure with one end open, and the open side of the first housing body 302 is engaged with the open side of the second housing body 303. Of course, the housing 301 formed by the first housing body 302 and the second housing body 303 may have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0090] In the battery 300, the plurality of battery cells 200 may be connected in series, in parallel, or in series-parallel, where series-parallel connection means that some of the plurality of battery cells 200 are connected in series and others are connected in parallel. The plurality of battery cells 200 may be directly connected in series, in parallel, or in series-parallel, and then the entirety of the plurality of battery cells 200 may be housed in the housing 301. Of course, the battery 300 may first have a plurality of battery cells 200 connected in series, in parallel, or in series-parallel to form a battery 300 module, and then the plurality of battery 300 modules may be connected in series, in parallel, or in series-parallel to form a whole and housed in the housing 301. The battery 300 may further include other structures, for example, the battery 300 may further include bus bar members for realizing electrical connection between the plurality of battery cells 200.

[0091] An electrode assembly 100 according to an embodiment of the present invention will now be described with reference to FIGS.

[0092] As shown in Figures 4 and 8, the present application provides an electrode assembly 100, which includes a positive electrode plate 10 and a negative electrode current collector 20 stacked along a first direction, and at least one of the positive electrode plate 10 and the negative electrode current collector 20 includes a substrate assembly 30 having a substrate layer 31 and an elastic layer 32, and the substrate layer 31 and the corresponding elastic layer 32 are stacked along the first direction.

[0093] Here, the elastic layer 32 is a metal member, and the battery cell 200 includes a case 201 and an electrode assembly 100. The electrode assembly 100 is mounted in the case 201. The outer surface of the negative electrode current collector 20 can be coated with a negative electrode active material layer 40. When the outer surface of the negative electrode current collector 20 is coated with the negative electrode active material layer 40, the negative electrode current collector 20 and the negative electrode active material layer 40 form a negative electrode plate. Alternatively, the outer surface of the negative electrode current collector 20 may not be coated with the negative electrode active material layer 40. When the outer surface of the negative electrode current collector 20 is not coated with the negative electrode active material layer 40, the battery cell 200 is a battery cell 200 without a negative electrode. The electrode assembly 100 may have a wound structure or a stacked structure. The present application will describe the electrode assembly 100 having a stacked structure as an example.

[0094] 4 and 5 , when the electrode assembly 100 is arranged as shown in FIGS. 4 and 5 , the first direction refers to the X direction in FIGS. 4 and 5 , the positive electrode plate 10 and the negative electrode current collector 20 are stacked along the first direction, and there may be multiple positive electrode plates 10 and multiple negative electrode current collectors 20, and the multiple positive electrode plates 10 are arranged in order along the first direction, with a negative electrode current collector 20 provided between any two adjacent positive electrode plates 10, and the multiple positive electrode plates 10 and multiple negative electrode current collectors 20 are stacked along the first direction. At least one of the positive electrode plate 10 and the negative electrode current collector 20 includes a substrate assembly 30, and it may be understood that the positive electrode plate 10 or the negative electrode current collector 20 includes the substrate assembly 30, or that both the positive electrode plate 10 and the negative electrode current collector 20 include the substrate assembly 30. This application will be described using the example where the negative electrode current collector 20 includes the substrate assembly 30.

[0095] The substrate assembly 30 includes a substrate layer 31 and an elastic layer 32, and the substrate layer 31 and the corresponding elastic layer 32 are stacked in a first direction. At least one negative electrode current collector 20 includes the substrate assembly 30. The present application will describe, as an example, a case in which each negative electrode current collector 20 includes a substrate assembly 30. The substrate layer 31 and the elastic layer 32 of each negative electrode current collector 20 are stacked in the first direction. The elastic layer 32 has elasticity, and when a compressive force is applied to the elastic layer 32, the thickness of the elastic layer 32 decreases. When the compressive force applied to the elastic layer 32 decreases, the elastic layer 32 has elasticity, and therefore the thickness of the elastic layer 32 increases and tends to return to its original state. During the charging process of the battery cell 200, metal ions (e.g., sodium ions) are deposited on the surface of the negative electrode current collector 20, causing the electrode assembly 100 to expand. During the expansion of the electrode assembly 100, the elastic layer 32 is compressed, and there is sufficient space within the case 201 of the battery cell 200 for the electrode assembly 100 to expand. The elastic layer 32 absorbs and relieves the volumetric expansion of the electrode assembly 100. The elastic layer 32 absorbs the expansion force of the electrode assembly 100 and reduces the force applied to the case 201 of the battery cell 200, reducing the risk of the battery cell 200 exploding and improving the service life and safety of the battery cell 200. Furthermore, the provision of the elastic layer 32 can also reduce the risk of the battery cell 200 being shut down and improving the operating performance of the battery cell 200.

[0096] In the above technical solution, by providing the elastic layer 32, during the charging process of the battery 300, the elastic layer 32 can be compressed and can absorb and mitigate the volume expansion of the electrode assembly 100. The elastic layer 32 absorbs the expansion force of the electrode assembly 100 and reduces the force applied to the case 201 of the battery cell 200, thereby reducing the risk of the battery cell 200 exploding and improving the service life and safety of the battery cell 200. Furthermore, by providing the elastic layer 32, the risk of breakage of the battery cell 200 can also be reduced and the operating performance of the battery cell 200 can be improved.

[0097] According to some embodiments of the present application, an elastic layer 32 is provided on at least one side of the base layer 31 along the first direction.

[0098] Here, as shown in Figure 6, along the first direction, the base layer 31 has opposing first and second sides, and the elastic layer 32 may be provided only on the first side of the base layer 31, or the elastic layer 32 may be provided only on the second side of the base layer 31, or the elastic layer 32 may be provided on both the first and second sides of the base layer 31. In this case, the base layer 31 is interposed between the two elastic layers 32, and this application will explain as an example the case where the elastic layer 32 is provided on one of the first and second sides of the base layer 31.

[0099] In the above technical solution, an elastic layer 32 is provided on at least one side of the substrate layer 31, so that when the positive electrode plate 10 and the negative electrode current collector 20 are stacked along a first direction, the elastic layer 32 can be positioned between the positive electrode plate 10 and the substrate layer 31. During the charging process of the battery cell 200, metal ions (e.g., sodium ions) are deposited on the surface of the negative electrode current collector 20, and then the elastic layer 32 can be compressed. The elastic layer 32 can absorb and mitigate the volume expansion of the electrode assembly 100, and reduce the stress caused by the volume expansion of the electrode assembly 100.

[0100] According to some embodiments of the present application, the substrate assembly 30 includes a plurality of substrate layers 31 stacked along a first direction, and an elastic layer 32 is provided between at least two adjacent substrate layers 31.

[0101] Here, as shown in FIG. 7 , each substrate assembly 30 may include multiple substrate layers 31 stacked along a first direction, with an elastic layer 32 provided between at least two adjacent substrate layers 31; for example, each substrate assembly 30 includes two substrate layers 31, with an elastic layer 32 provided between the two substrate layers 31; in this embodiment, the elastic layer 32 is interposed between the two substrate layers 31.

[0102] In the above technical solution, an elastic layer 32 is provided between two adjacent base layers 31. During charging of the battery cell 200, a metal ion (e.g., sodium ion) layer is deposited on the surface of the base layer 31 away from the elastic layer 32. After the metal ions are deposited on the surface of the base layer 31, the elastic layer 32 is compressed by the expansion force. The elastic layer 32 can absorb and mitigate the volume expansion of the electrode assembly 100, and reduce the stress caused by the volume expansion of the electrode assembly 100.

[0103] According to some embodiments of the present application, the elastic layer 32 is connected to the adjacent substrate layer 31 .

[0104] Here, the elastic layer 32 is connected to the adjacent base layer 31, and the adjacent elastic layers 32 of each base assembly 30 are connected to the base layer 31. There are no specific limitations on the method of connection between the elastic layer 32 and the base layer 31, as long as the elastic layer 32 and the base layer 31 can be connected. For example, the elastic layer 32 and the base layer 31 may be connected by being attached, or the elastic layer 32 and the base layer 31 may be fixed and connected via a fastening material.

[0105] In the above technical solution, the elastic layer 32 is connected to the base layer 31, so that the elastic layer 32 and the base layer 31 are fixedly attached, reducing the risk of misalignment between the elastic layer 32 and the base layer 31. The elastic layer 32 can be securely attached between the base layer 31 and the positive electrode plate 10. During the charging process of the battery cell 200, metal ions are deposited on the surface of the negative electrode current collector 20, and the expansion force causes the elastic layer 32 to be compressed in the first direction, so that the elastic layer 32 can absorb and mitigate the volume expansion of the electrode assembly 100.

[0106] According to some embodiments of the present application, the elastic layer 32 is adhesively secured to the adjacent substrate layer 31 .

[0107] Here, the elastic layer 32 can be adhered and fixed to the adjacent base layer 31 via a structural adhesive, and the adjacent elastic layer 32 and base layer 31 in each base assembly 30 are adhered and fixed.

[0108] In the above technical proposal, the elastic layer 32 is adhered and fixed to the adjacent base layer 31, thereby reliably fixing the elastic layer 32 and the base layer 31, reducing the risk of the elastic layer 32 and the base layer 31 separating and reducing the risk of misalignment between the elastic layer 32 and the base layer 31. Furthermore, the elastic layer 32 is adhered and fixed to the base layer 31, which simplifies the process of attaching the elastic layer 32 and the base layer 31 and improves the efficiency of attaching the elastic layer 32 and the base layer 31.

[0109] According to some embodiments of the present application, along a first direction, the base layer 31 has a first side 311, the elastic layer 32 has a second side 321, and the first side 311 abuts against the corresponding second side 321.

[0110] Here, along the first direction, the side of the base layer 31 facing the elastic layer 32 is the first side 311, and the side of the elastic layer 32 facing the base layer 31 is the second side 321, and when the base layer 31 and the elastic layer 32 are stacked along the first direction, the first side 311 abuts against the corresponding second side 321. Specifically, as shown in FIG. 6 , in this embodiment, an elastic layer 32 is provided on one side of the base layer 31, the side of the base layer 31 facing the elastic layer 32 is a first side 311, and the side of the elastic layer 32 facing the base layer 31 is a second side 321, the base layer 31 has one first side 311, and the elastic layer 32 has one second side 321, and when the base layer 31 and the elastic layer 32 are stacked along the first direction, the first side 311 is provided opposite the second side 321 and abuts the second side 321. As shown in Figure 7, in this embodiment, the elastic layer 32 is interposed between two adjacent base layers 31, and the side of each base layer 31 facing the elastic layer 32 is a first side 311, each base layer 31 has one first side 311, and the sides of the elastic layer 32 facing each of the two adjacent base layers 31 are second side sides 321, and the elastic layer 32 has two second side sides 321, and the two second side sides 321 of the elastic layer 32 are respectively arranged opposite the first side sides 311 of the two base layers 31, and the second side sides 321 abut against the opposing first side sides 311.

[0111] In the above technical solution, the first side 311 of the substrate layer 31 abuts the second side 321 of the elastic layer 32, so that during the charging process of the battery cell 200, metal ions (e.g., sodium ions) are deposited on the surface of the negative electrode current collector 20, and then the expansion force can be transmitted to the elastic layer 32, causing the elastic layer 32 to compress. The elastic layer 32 can absorb and mitigate the volume expansion of the electrode assembly 100, and reduce the stress caused by the volume expansion of the electrode assembly 100.

[0112] According to some embodiments of the present application, both the first side surface 311 and the second side surface 321 are configured as flat surfaces.

[0113] Here, the first side surface 311 and the second side surface 321 are both configured as flat surfaces, and after the elastic layer 32 and the base layer 31 are attached, the elastic layer 32 and the base layer 31 are brought into surface contact with each other.

[0114] In the above technical solution, by making both the first side 311 and the second side 321 flat, the first side 311 and the second side 321 can be made more flat. After the elastic layer 32 and the base layer 31 are attached, the contact area between the first side 311 and the second side 321 can be increased, and the first side 311 and the second side 321 can be reliably contacted. During the charging process of the battery cell 200, after metal ions (e.g., sodium ions) are deposited on the surface of the negative electrode current collector 20, the force applied to the elastic layer 32 can be made uniform, the elastic layer 32 can be compressed more uniformly, and the risk of stress concentration in the elastic layer 32 can be reduced.

[0115] According to some embodiments of the present application, along the first direction, the orthogonal projection of the substrate layer 31 lies within the orthogonal projection of the elastic layer 32 .

[0116] Here, along the first direction, i.e., along the direction in which the positive electrode plate 10 and the negative electrode current collector 20 are stacked, the orthogonal projection of the substrate layer 31 is located within the orthogonal projection of the elastic layer 32, and the range of the orthogonal projection of the substrate layer 31 is located within the range of the orthogonal projection of the elastic layer 32. The area of ​​the orthogonal projection of the substrate layer 31 may be smaller than the area of ​​the orthogonal projection of the elastic layer 32, or the area of ​​the orthogonal projection of the substrate layer 31 may be equal to the area of ​​the orthogonal projection of the elastic layer 32, in which case the orthogonal projection of the substrate layer 31 completely overlaps the orthogonal projection of the elastic layer 32.

[0117] In the above technical solution, the orthogonal projection of the substrate layer 31 is located within the orthogonal projection of the elastic layer 32. Therefore, during the charging process of the battery cell 200, metal ions (e.g., sodium ions) are deposited on the surface of the negative electrode current collector 20, and then can compress the elastic layer 32, transmitting the expansion force to the elastic layer 32. The elastic layer 32 can absorb and mitigate the volume expansion of the electrode assembly 100, and reduce the stress caused by the volume expansion of the electrode assembly 100.

[0118] According to some embodiments of the present application, the outer surface of the negative electrode current collector 20 has a negative electrode active material layer 40 thereon.

[0119] Here, the negative electrode active material layer 40 is provided on the outer surface of the negative electrode current collector 20, and more specifically, the negative electrode active material layer 40 is provided on the outer surface of the substrate layer 31. The type of the negative electrode active material layer 40 may be reasonably selected depending on the actual usage conditions, and is not specifically limited herein.

[0120] In the above technical solution, the negative electrode active material layer 40 is provided on the outer surface of the negative electrode current collector 20 to form a negative electrode plate, and the battery cell 200 can have a positive electrode plate 10 and a negative electrode plate.

[0121] According to some embodiments of the present application, the elastic layer 32 is a high molecular weight polymer.

[0122] Here, the polymer may be one or more of materials such as PET (polyethylene terephthalate), PP (polypropylene), and PI (polyimide). Polyethylene terephthalate has better temperature resistance and adhesive strength, while polypropylene has better corrosion resistance, which is more advantageous in the electrolyte of the battery cell 200. The non-polar polypropylene base material has strong acid and alkali resistance, resulting in better performance when applied to the battery 300.

[0123] In the above technical solution, the elastic layer 32 is made of a high molecular weight polymer, which can improve the temperature resistance, adhesive strength, and corrosion resistance of the elastic layer 32, thereby improving the performance of the battery cell 200.

[0124] According to some embodiments of the present application, the thickness of the substrate layer 31 is 5% to 80% of the total thickness of the substrate assembly 30, and the thickness of the elastic layer 32 is 20% to 95% of the total thickness of the substrate assembly 30.

[0125] Here, when no force is applied to the substrate assembly 30, the thickness of the substrate layer 31 is 5% to 80% of the total thickness of the substrate assembly 30, for example, the thickness of the substrate layer 31 is 5% of the total thickness of the substrate assembly 30, or the thickness of the substrate layer 31 is 80% of the total thickness of the substrate assembly 30, or the thickness of the substrate layer 31 is 50% of the total thickness of the substrate assembly 30. The thickness of the elastic layer 32 is 20% to 95% of the total thickness of the substrate assembly 30, for example, the thickness of the elastic layer 32 is 20% of the total thickness of the substrate assembly 30, or the thickness of the elastic layer 32 is 95% of the total thickness of the substrate assembly 30, or the thickness of the elastic layer 32 is 60% of the total thickness of the substrate assembly 30.

[0126] The above technical solution reduces the space occupied by the elastic layer 32 in the initial uncompressed state, thereby reducing the risk of affecting the space of the electrode assembly 100 and losing energy density, and also ensures the space occupied by the elastic layer 32 and increases the compressible space of the elastic layer 32, thereby effectively absorbing the expansion of the electrode assembly 100.

[0127] According to some embodiments of the present application, the initial thickness of the elastic layer 32 is D1, and the compressed thickness of the elastic layer 32 is D2, which satisfies the relationship 0.1≦1−D2 / D1≦0.95.

[0128] Here, the initial thickness of the elastic layer 32 refers to the thickness of the elastic layer 32 in an uncompressed, free state, and the compressed thickness of the elastic layer 32 refers to the thickness when a force is applied to the elastic layer 32 and it is compressed. For example, "1-D2 / D1" is 0.1, or "1-D2 / D1" is 0.95, or "1-D2 / D1" is 0.6.

[0129] In the above technical solution, the elastic layer 32 has sufficient compressibility, and the elastic layer 32 is compressively deformed as the electrode assembly 100 expands, and can absorb the expansion of the electrode assembly 100. At the same time, processing problems caused by excessively large compressibility, such as deformation and rebound during the production of the electrode assembly 100, are reduced.

[0130] According to some embodiments of the present application, the elastic layer 32 has a hollowed-out structure.

[0131] Here, the hollowed-out structure has the effect of reducing weight, and by providing the hollowed-out structure in the elastic layer 32, the weight of the elastic layer 32 can be reduced.

[0132] In the above technical solution, by providing a hollowed-out structure in the elastic layer 32, the weight of the elastic layer 32 can be reduced, and the weight of the electrode assembly 100 can be reduced, thereby reducing the weight of the battery cell 200, which is advantageous for achieving a lightweight design of the battery cell 200.

[0133] According to some embodiments of the present application, the lightening structure is a lightening hole and / or a lightening groove.

[0134] Here, the lightening structure may be provided as a lightening hole and / or a lightening groove, and may be understood as a lightening hole, a lightening groove, or a lightening hole and a lightening groove. The lightening hole may penetrate the elastic layer 32 along the thickness direction of the elastic layer 32.

[0135] In the above technical proposal, by providing the cutout structure as a cutout hole and / or a cutout groove, the structure of the cutout structure can be simplified, and the cutout structure can be easily provided in the elastic layer 32, thereby simplifying the structure of the elastic layer 32.

[0136] According to some embodiments of the present application, the electrode assembly 100 further includes a separator 50 disposed between the positive electrode plate 10 and the negative electrode current collector 20 to separate the positive electrode plate 10 from the negative electrode current collector 20 .

[0137] Here, as shown in FIGS. 4 and 5 , the electrode assembly 100 further includes a separator 50 disposed between the positive electrode plate 10 and the negative electrode current collector 20. The separator 50 can separate the positive electrode plate 10 from the negative electrode current collector 20, allows metal ions to pass through the separator 50, and serves as an insulator. The specific structure and manufacturing materials of the separator 50 may be specifically set according to the actual usage conditions, and are not specifically limited herein.

[0138] In the above technical solution, the separator 50 is disposed between the positive electrode plate 10 and the negative electrode current collector 20, so that the separator 50 separates the positive electrode plate 10 and the negative electrode current collector 20, preventing short circuits caused by contact between the positive electrode plate 10 and the negative electrode current collector 20, and improving the safety of the use of the battery cell 200.

[0139] According to some embodiments of the present application, referring to Figures 9 and 10, in the thickness direction of the separator 50, the separator 50 has a positive electrode end 11 provided near the positive electrode plate 10 and having a plurality of first openings 110, and a negative electrode end 12 provided near the negative electrode current collector 20 and having a plurality of second openings 120, and the hole diameter of the first openings 110 is larger than the hole diameter of the second openings 120.

[0140] It should be noted that the "positive electrode end 11 of the separator 50" may be understood to be the end of the separator 50 that is closer to the positive electrode plate 10 after the positive electrode plate 10, the separator 50, and the negative electrode current collector 20 are stacked together to assemble the battery cell 200, and similarly, the "negative electrode end 12 of the separator 50" may be understood to be the end of the separator 50 that is closer to the negative electrode current collector 20 after the positive electrode plate 10, the separator 50, and the negative electrode current collector 20 are stacked together to assemble the battery cell 200. In addition, "plurality" means two or more than two.

[0141] Without wishing to be limited to any theory, the inventors have conducted extensive research and have concluded that by providing first openings 110 at the positive electrode end 11 of the separator 50 and second openings 120 at the negative electrode end 12 of the separator 50, and the diameter of the first openings 110 is larger than the diameter of the second openings 120, the volume expansion of the negative electrode current collector 20 during the cycle process of the battery 300 presses against the negative electrode end 12 of the separator 50, and the compression of the negative electrode end 12 is greater than that of the positive electrode end 11, which makes it easy for the electrolyte to dry up between the negative electrode end 12 of the separator 50 and the negative electrode current collector 20, On the other hand, in the present application, second small-sized openings 120 are provided in the negative electrode end 12 of the separator 50. The second small-sized openings 120 have an excellent liquid retention effect, making it difficult for the electrolyte to dry up between the separator 50 and the negative electrode current collector 20, thereby reducing capacity loss in the battery 300. Furthermore, the negative electrode end 12 provided with the second small-sized openings 120 has excellent density, thereby reducing the probability of a short circuit caused by metal dendrites formed on the surface of the negative electrode current collector 20 piercing the separator 50, and improving the safety of the battery 300. Furthermore, it has been found that by providing the positive electrode terminal 11 with first openings 110 having a relatively large pore size and the negative electrode terminal 12 with second openings 120 having a relatively small pore size, the concentration gradient of metal ion diffusion can be adjusted during charging of the battery 300, allowing the metal ions to be uniformly deposited on the surface of the negative electrode current collector 20, reducing the possibility of metal dendrite formation and reducing the volumetric expansion of the negative electrode current collector 20, thereby improving the safety of the battery 300. As a result, by employing the separator 50 of the present application, it is possible to solve the problems of capacity loss and safety of the battery 300 caused by the volumetric expansion of the negative electrode current collector 20 during cycling of the metal battery 300.

[0142] As a result of extensive research, the inventors of the present application have found that if the separator 50 of the present application satisfies the above conditions and can further selectively satisfy one or more of the following conditions, the capacity loss of the battery 300 can be further reduced and the safety performance of the battery 300 can be further improved.

[0143] According to some embodiments of the present application, the diameter of the first apertures 110 is 20 nm to 1000 μm.

[0144] Here, for example, 30 nm to 1000 μm, 40 nm to 1000 μm, 50 nm to 1000 μm, 60 nm to 1000 μm, 70 nm to 1000 μm, 80 nm to 1000 μm, 90 nm to 1000 μm, 100 nm to 1000 μm, 200 nm to 1000 μm, 300 nm to 1000 μm, 400 nm to 1000 μm, 500 nm to 1000 μm, 600 nm to 100 0 μm, 700 nm to 1000 μm, 800 nm to 1000 μm, 900 nm to 1000 μm, 1000 nm to 1000 μm, 10 μm to 1000 μm, 50 μm to 900 μm, 100 μm to 800 μm, 150 μm to 750 μm, 200 μm to 700 μm, 250 μm to 650 μm, 300 μm to 600 μm, 350 μm to 550 μm, 400 μm to 500 μm. The inventors found that if the diameter of the first openings 110 is too small, the ionic conductivity of the positive electrode terminal 11 is relatively poor. On the other hand, if the diameter of the first openings 110 is too large, the positive electrode terminal 11 of the separator 50 adsorbs a large amount of electrolyte. When the volume of the negative electrode current collector 20 expands and presses against the separator 50 during charging and discharging, the electrolyte adsorbed by the positive electrode terminal 11 does not return in time, resulting in a blockage of some of the electrolyte, which is unevenly deposited on the surface of the negative electrode current collector 20. Furthermore, some micro-short circuits caused by the influence of particles such as powder falling off of the active material layer on the positive electrode plate 10 cannot be prevented. In some embodiments, the diameter of the first openings 110 is preferably 50 nm to 500 μm. That is, the diameter of the first openings 110 of the positive electrode terminal 11 is preferably 50 nm to 500 μm.

[0145] The above technical solution can improve the liquid retention effect of the negative electrode end 12 of the separator 50 and increase its density, thereby resolving the capacity loss and safety issues of the battery 300 caused by the volume expansion of the negative electrode current collector 20 during the cycling process of the battery 300.

[0146] According to some embodiments of the present application, the second pores 120 have a diameter of 20 nm to 500 μm.

[0147] Here, the pore size of the second openings 120 of the negative electrode terminal 12 of the separator 50 is 20 nm to 500 μm, for example, 30 nm to 500 μm, 40 nm to 500 μm, 50 nm to 500 μm, 60 nm to 500 μm, 70 nm to 500 μm, 80 nm to 500 μm, 90 nm to 500 μm, 100 nm to 500 μm, 200 nm to 500 μm, 300 nm ~500μm, 400nm~500μm, 500nm~500μm, 600nm~500μm, 700nm~500μm, 800nm~500μm, 900nm~500μm, 1000nm~500μm, 10μm~500μm, 50μm~450μm, 100μm~400μm, 150μm~350μm, 200μm~300μm. As a result, the second openings 120 that satisfy this pore size improve the liquid retention effect of the negative electrode terminal 12 and make it less likely that the electrolyte will dry up between the separator 50 and the negative electrode current collector 20, thereby reducing capacity loss in the battery 300. Furthermore, the density of the negative electrode terminal 12 can be improved, reducing the probability of a short circuit caused by metal dendrites forming on the surface of the negative electrode current collector 20 and piercing the separator 50, thereby improving the safety of the battery 300. In some embodiments, the pore size of the second openings 120 is preferably 50 nm to 100 μm, i.e., the pore size of the second openings 120 in the negative electrode terminal 12 is preferably 50 nm to 100 μm.

[0148] According to some embodiments of the present application, the pore diameter of the separator 50 increases in the direction from the negative electrode end 12 to the positive electrode end 11 .

[0149] In the above technical solution, the openings in the separator 50 are arranged to increase in size in the direction from the negative electrode end 12 to the positive electrode end 11. This further adjusts the concentration gradient of metal ion diffusion during charging of the battery 300, allowing the metal ions to be uniformly deposited on the surface of the negative electrode current collector 20, reducing the occurrence of metal dendrites and the volumetric expansion of the negative electrode current collector 20, thereby improving the safety of the battery 300.

[0150] According to some embodiments of the present application, a capillary structure 13 is provided within the separator 50 along its height, with one end flush with the bottom end of the separator 50 .

[0151] 11, in order to further improve the liquid retention effect of separator 50, a capillary structure 13 is provided in separator 50 along its height direction, with one end flush with the bottom end of separator 50. As a result, when the volume of negative electrode current collector 20 expands and presses against separator 50, the siphon effect of the capillary allows the electrolyte at the bottom of battery cell 200 to be siphon-siphoned up into separator 50, allowing any shortage of electrolyte in the height direction of separator 50 to be quickly replenished.

[0152] According to some embodiments of the present application, the length H1 of the capillary structure 13 is 70% H2, where H2 is the height of the separator 50.

[0153] Here, for example, H1 is 70% H2, 75% H2, 80% H2, 85% H2, 90% H2, 95% H2, or 100% H2. This allows the electrolyte at the bottom of the battery cell 200 to be siphoned up to the top of the separator 50, quickly replenishing any shortage of electrolyte at the top of the separator 50.

[0154] According to some embodiments of the present application, the capillary structure 13 can be a tree-like structure, for example, a combination of a main large-port structure and a branched small-port structure, with the branched small-port structure connected to the main large-port structure. This allows the main large-port structure to siphon the electrolyte at the bottom of the battery cell 200 to the upper layer of the separator 50, and the branched small-port structure to transport the electrolyte to each layer within the separator 50, allowing a shortage of electrolyte within the separator 50 to be quickly replenished.

[0155] According to some embodiments of the present application, the compressive elastic modulus of the separator 50 is 5% to 95%, for example, 10% to 90%, 20% to 80%, 30% to 70%, 40% to 60%, or 40% to 50%. Thus, by employing a separator 50 with the compressive elastic modulus of the present application, when volume expansion occurs in the negative electrode current collector 20, swelling of the battery 300 caused by the volume expansion of the negative electrode current collector 20 can be effectively alleviated, thereby improving the safety performance of the battery 300.

[0156] According to some embodiments of the present application, the compressive modulus of separator 50 is tested using a universal testing machine (MDTC-EQ-M12-01). Specifically, the method includes Step 1 of selecting a separator to be tested, in which multiple layers are stacked and tested to ensure that the sample thickness is ≥ 1 mm, thereby minimizing accuracy errors; Step 2 of collecting initial thicknesses, in which an initial pressure is applied to the separator (an initial value of ≥ 0.05 MPa is tested) to obtain the initial thickness of the separator at that constant pressure; and Step 3 of collecting compressive moduli, in which pressure is continued to be applied to the separator until the thickness becomes constant and the pressure / compression strength shows an inflection point where it increases exponentially, at which point data collection is considered complete. The slope of the initial segment of the strain-stress curve corresponds to the compressive modulus of the sample, thereby obtaining the compressive moduli of different target samples.

[0157] According to some embodiments of the present application, separator 50 is a sponge-based film.

[0158] It should be noted that the "sponge-based film" may be understood as a film having a sponge-like structure, and for example, the sponge-based film may include at least one of glass fiber, nanofiber, polyethylene, polypropylene, and nonwoven fabric.

[0159] According to some embodiments of the present application, the separator 50 includes a sponge base film 14 and a coating layer 15, the coating layer 15 being formed on at least one side of the sponge base film 14, and the capillary structure 13 being provided on the sponge base film 14.

[0160] To further improve the safety performance of the battery 300, referring to FIGS. 12 and 13, the separator 50 includes a sponge base film 14 and a coating layer 15, the coating layer 15 being formed on at least one side of the sponge base film 14, and the capillary structures 13 being formed on the sponge base film 14. For example, referring to FIG. 12, the coating layer 15 is formed on one side of the sponge base film 14, the second openings 120 are formed in the coating layer 15, and the first openings 110 are formed on one side of the sponge base film 11 away from the coating layer 15. Thus, by employing the sponge base film 14 including the capillary structures 13, the liquid retention effect of the separator 50 can be improved. Furthermore, by providing the coating layer 15 on one side of the sponge base film 14 and providing the second openings 120 in the coating layer 15 as the negative electrode end 12 of the separator 50, the puncture resistance and high temperature resistance of the separator 50 can be significantly improved, thereby improving the safety performance of the battery 300.

[0161] 13, according to some embodiments of the present application, the coating layer 15 is provided on both sides of the sponge base film 14, the second openings 120 are provided in the coating layer 15 located at the negative electrode end 12, and the first openings 110 are provided in the coating layer 15 at the positive electrode end 11. In this way, by adopting the sponge base film 14 including the capillary structure 13, the liquid retention effect of the separator 50 can be improved, and the coating layers 15 are provided on both sides of the sponge base film 14, which significantly improves the high temperature resistance of the separator 50 and improves the safety performance of the battery 300.

[0162] According to some embodiments of the present application, the coating layer 15 may include an inorganic particle coating layer or a gel electrolyte coating layer. For example, the inorganic particles employed in the inorganic particle coating layer may include one or more of boehmite (γ-AlOOH), alumina (AlO), barium sulfate (BaSO), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)), silica (SiO), tin dioxide (SnO), titanium oxide (TiO), calcium oxide (CaO), zinc oxide (ZnO), zirconia (ZrO), yttrium oxide (YO), nickel oxide (NiO), cerium oxide (CeO), zirconium titanate (SrTiO), barium titanate (BaTiO), and magnesium fluoride (MgF). These types of inorganic particles have a good effect of suppressing thermal shrinkage of the separator 50, thereby improving the high temperature resistance and puncture resistance of the separator 50. For example, the gel electrolyte in the gel electrolyte coating layer may include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer [P(VDFHFP)], polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), etc.

[0163] According to some embodiments of the present application, the thickness of the inorganic particle coating layer is 0.5 μm to 8 μm, for example, 1 μm to 8 μm, 1.5 μm to 7.5 μm, 2 μm to 7 μm, 2.5 μm to 6.5 μm, 3 μm to 6 μm, 3.5 μm to 5.5 μm, or 4 μm to 5 μm, which can improve the high temperature resistance and puncture resistance of the separator 50 and improve the safety performance of the battery 300.

[0164] According to some embodiments of the present application, the thickness of the gel electrolyte coating layer is 5 μm to 15 μm, for example, 6 μm to 15 μm, 7 μm to 14 μm, 8 μm to 13 μm, 9 μm to 12 μm, or 10 μm to 11 μm, which can improve the high temperature resistance and puncture resistance of the separator 50 and improve the safety performance of the battery 300.

[0165] According to some embodiments of the present application, the inorganic particle coating layer and the gel electrolyte coating layer may further include an adhesive, and for example, the adhesive may be one or more of styrene butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0166] According to some embodiments of the present application, the inorganic particle coating layer and the gel electrolyte coating layer may further contain other organic compounds, such as a polymer for improving heat resistance, a dispersant, a wetting agent, and other types of adhesives. The present application does not particularly limit the type of the other organic compounds, and any known material with excellent improving properties may be used.

[0167] 14 , according to some embodiments of the present application, the separator 50 includes a first separation membrane 500, an intermediate separation membrane 600, and a second separation membrane 700 stacked along its thickness direction, with the first openings 110 provided in the first separation membrane 500 and the second openings 120 provided in the second separation membrane 700. Illustratively, the pore size of the intermediate separation membrane 600 is larger than the pore size of the first openings 110 or the pore size of the second openings 120, and / or the porosity of the intermediate separation membrane 600 is larger than the porosity of the first separation membrane 500 or the second separation membrane 700. Thus, by employing an intermediate separation membrane 600 with a relatively large pore size and / or a relatively large porosity, a larger amount of electrolyte can be stored. As a result, when the volume of the negative electrode current collector 20 expands and presses against the electrolyte between the negative electrode current collector 20 and the separator 50, the electrolyte stored in the intermediate separation membrane 600 can quickly replenish the insufficient electrolyte between the negative electrode current collector 20 and the separator 50.

[0168] According to some embodiments of the present application, the first separation membrane 500, the intermediate separation membrane 600, and the second separation membrane 700 satisfy at least one of the following conditions: the porosity of the first separation membrane 500 is 30% to 70%, the pore size of the intermediate separation membrane 600 is 30 nm to 1 μm, the porosity of the intermediate separation membrane 600 is 40% to 90%, and the porosity of the second separation membrane 700 is 30% to 70%.

[0169] Here, the pore size of the intermediate separation membrane 600 is 30 nm to 1 μm, for example, 30 nm to 1 μm, 40 nm to 1 μm, 50 nm to 1 μm, 60 nm to 1 μm, 70 nm to 1 μm, 80 nm to 1 μm, 90 nm to 1 μm, 100 nm to 1 μm, 200 nm to 1 μm, 300 nm to 1 μm, 400 nm to 1 μm, 500 nm to 1 μm, 600 nm to 1 μm, 700 nm to 1 μm, 800 nm to 1 μm, or 900 nm to 1 μm. As a result, the intermediate separation membrane 600 having such a pore size can store a larger amount of electrolyte, thereby quickly replenishing any shortage of electrolyte between the negative electrode current collector 20 and the separator 50.

[0170] In some embodiments, the porosity of the first separation membrane 500 is 30% to 70%, for example, 35% to 70%, 40% to 70%, 45% to 70%, 50% to 70%, 55% to 70%, 60% to 70%, or 65% to 70%, and the porosity of the intermediate separation membrane 600 is 40% to 90%, for example, 45% to 90%, 50% to 90%, 55% to 70%, 60% to 70%, or 65% to 70%. The porosity of the second separator 700 is 30% to 70%, for example, 35% to 70%, 40% to 70%, 45% to 70%, 50% to 70%, 55% to 70%, 60% to 70%, or 65% to 70%. This allows the intermediate separator 600 with such a porosity to store a larger amount of electrolyte, thereby quickly replenishing any shortage of electrolyte between the negative electrode current collector 20 and the separator 50.

[0171] According to some embodiments of the present application, the porosity of the first separation membrane 500, the intermediate separation membrane 600, and the second separation membrane 700 may be determined by a gas displacement method. Specifically, referring to GB / T 24586-2009, the porosity may be determined by immersing the separator in ethyl methyl carbonate (EMC) to clean it, and then measuring by a gas displacement method. Here, the porosity of the separator is the proportion of the pore volume of the separator to the total volume of the separator, and is calculated by the formula: porosity = (V - V0) / V × 100%, where V0 is the true volume and V is the apparent volume.

[0172] According to some embodiments of the present application, the present application further provides a battery cell 200 including the electrode assembly 100 of the above-described embodiments. Here, the battery cell 200 may further include a case 201, and the electrode assembly 100 is mounted in the case 201.

[0173] According to some embodiments of the present application, the present application further provides a battery 300 including the battery cell 200 of the above embodiment. Here, the battery 300 may further include a housing 301, and the battery cell 200 is mounted in the housing 301.

[0174] According to some embodiments of the present application, the present application further provides a power consuming device 400 including the battery 300 of the above embodiment. The battery 300 is used to provide power to the power consuming device 400.

[0175] According to some embodiments of the present application, as shown in FIG. 4 , the present application provides an electrode assembly 100, which includes a separator 50, a positive electrode plate 10, and a negative electrode current collector 20, wherein the separator 50, the positive electrode plate 10, and the negative electrode current collector 20 are stacked along a first direction, the separator 50 is provided between the positive electrode plate 10 and the negative electrode current collector 20, and the separator 50 separates the positive electrode plate 10 and the negative electrode current collector 20, and the negative electrode current collector 20 includes a substrate assembly 30 having an elastic layer 32 and a plurality of substrate layers 31, wherein the plurality of substrate layers 31 are stacked along the first direction, and the elastic layer 32 is provided between two adjacent substrate layers 31.

[0176] 4 and the electrode assembly 100 in FIG. 5 differ in that a negative electrode active material layer 40 is not provided on the outer surface of the negative electrode current collector 20 in FIG. 4, whereas a negative electrode active material layer 40 is provided on the outer surface of the negative electrode current collector 20 in FIG. 5. The substrate assembly 30 in FIG. 6 and the substrate assembly 30 in FIG. 7 differ in that a substrate layer 31 is provided on one side of the elastic layer 32 of the substrate assembly 30 in the embodiment of FIG. 6, whereas a substrate layer 31 is provided on both sides of the elastic layer 32 of the substrate assembly 30 in the embodiment of FIG. 7, with the elastic layer 32 being provided between the two substrate layers 31. The substrate assembly 30 in FIG. 7 and the substrate assembly 30 in FIG. 8 differ in that a negative electrode active material layer 40 is provided on the outer surface of the substrate assembly 30 in FIG. 8.

[0177] In addition, unless there is a conflict, the embodiments and features of the embodiments in the present application can be combined with each other.

[0178] The above is merely a preferred embodiment of the present application, and is not intended to limit the present application. Those skilled in the art may have various modifications and variations to the present application. Any modifications, equivalent replacements, improvements, etc. that do not deviate from the spirit and intent of the present application shall be included in the protection scope of the present application.

Claims

1. an electrode assembly comprising: a positive electrode plate and a negative electrode current collector stacked along a first direction, wherein at least one of the positive electrode plate and the negative electrode current collector includes a substrate assembly having a substrate layer and an elastic layer, the substrate layer and the corresponding elastic layer being stacked along the first direction.

2. The electrode assembly according to claim 1 , wherein the elastic layer is provided on at least one side of the base material layer along the first direction.

3. 2. The electrode assembly according to claim 1, wherein the substrate assembly has a plurality of the substrate layers stacked along the first direction, and the elastic layer is provided between at least two adjacent substrate layers.

4. The electrode assembly according to any one of claims 1 to 3, wherein the elastic layer is connected to the adjacent base layer.

5. The electrode assembly according to claim 4 , wherein the elastic layer is adhesively fixed to the adjacent base layer.

6. 6. The electrode assembly according to claim 1, wherein the base material layer has a first side and the elastic layer has a second side along the first direction, and the first side abuts against the corresponding second side.

7. The electrode assembly according to claim 6 , wherein the first side surface and the second side surface are both configured as flat surfaces.

8. 8. The electrode assembly according to claim 1, wherein an orthogonal projection of the base layer is located within an orthogonal projection of the elastic layer along the first direction.

9. 9. The electrode assembly according to claim 1, wherein the outer surface of the negative electrode current collector has a negative electrode active material layer.

10. 10. The electrode assembly according to claim 1, wherein the elastic layer is a high molecular weight polymer.

11. The electrode assembly according to any one of claims 1 to 10, characterized in that the thickness of the substrate layer is 5% to 80% of the total thickness of the substrate assembly, and the thickness of the elastic layer is 20% to 95% of the total thickness of the substrate assembly.

12. The electrode assembly according to any one of claims 1 to 11, characterized in that the initial thickness of the elastic layer is D1, the compressed thickness of the elastic layer is D2, and the relationship 0.1≦1−D2 / D1≦0.95 is satisfied.

13. 13. The electrode assembly according to claim 1, wherein the elastic layer has a hollowed-out structure.

14. The electrode assembly according to claim 13 , wherein the lightening structure is a lightening hole and / or a lightening groove.

15. The electrode assembly according to any one of claims 1 to 14, further comprising a separator provided between the positive electrode plate and the negative electrode current collector to separate the positive electrode plate and the negative electrode current collector.

16. 16. The electrode assembly according to claim 15, wherein the separator has, in a thickness direction of the separator, a positive electrode end provided near the positive electrode plate and having a plurality of first openings, and a negative electrode end provided near the negative electrode current collector and having a plurality of second openings, the diameter of the first openings being larger than the diameter of the second openings.

17. 17. The electrode assembly according to claim 16, wherein the diameter of the first apertures is 20 nm to 1000 μm, preferably 50 nm to 500 μm.

18. 17. The electrode assembly according to claim 16, wherein the diameter of the second apertures is 20 nm to 500 μm, preferably 50 nm to 100 μm.

19. 17. The electrode assembly according to claim 16, wherein the pore diameters of the separator pores increase in a direction from the negative electrode end to the positive electrode end.

20. 17. The electrode assembly of claim 16, wherein a capillary structure is provided within the separator along its height, one end of which is flush with the bottom end of the separator.

21. 21. The electrode assembly of claim 20, wherein the length of the capillary structure is H1 > 70% H2, where H2 is the height of the separator.

22. 16. The electrode assembly according to claim 15, wherein the separator has a compressive modulus of elasticity of 5% to 95%.

23. 16. The electrode assembly of claim 15, wherein the separator is a sponge-based film.

24. 21. The electrode assembly of claim 20, wherein the separator includes a sponge base film and a coating layer formed on at least one side of the sponge base film, and the capillary structure is provided on the sponge base film.

25. 25. The electrode assembly of claim 24, wherein the sponge-based film comprises at least one of glass fiber, nanofiber, polyethylene, polypropylene, and nonwoven fabric.

26. 26. The electrode assembly of claim 25, wherein the coating layer is formed on one side of the sponge base film, the second opening is provided in the coating layer, and the first opening is provided at an end of the sponge base film away from the coating layer.

27. 26. The electrode assembly of claim 25, wherein the coating layer is formed on both sides of the sponge base film, the second opening is provided in the coating layer located at the negative electrode end, and the first opening is provided in the coating layer located at the positive electrode end.

28. 17. The electrode assembly of claim 16, wherein the separator includes a first separator, an intermediate separator, and a second separator stacked along its thickness direction, the first opening being formed in the first separator, and the second opening being formed in the second separator.

29. 29. The electrode assembly of claim 28, wherein the pore size of the intermediate separation membrane is larger than the pore size of the first opening or the pore size of the second opening, and / or the porosity of the intermediate separation membrane is larger than the porosity of the first separation membrane or the second separation membrane.

30. 30. The electrode assembly of claim 29, wherein the first separation membrane, the intermediate separation membrane, and the second separation membrane satisfy at least one of the following conditions: the porosity of the first separation membrane is 30% to 70%, the pore size of the intermediate separation membrane is 30 nm to 1 μm, the porosity of the intermediate separation membrane is 40% to 90%, and the porosity of the second separation membrane is 30% to 70%.

31. A battery cell comprising the electrode assembly according to any one of claims 1 to 30.

32. A battery comprising the battery cell of claim 31.

33. 33. A power consuming device comprising the battery of claim 32.

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