Battery cell, separator, battery device, and electric device

Abstract

The embodiment of the application provides a battery monomer, a separation film, a battery device and a power utilization device, and belongs to the technical field of batteries. The battery monomer comprises a shell and an electrode assembly, the electrode assembly is arranged in the shell, the electrode assembly comprises a first pole piece, a separation film and a second pole piece, and the separation film is arranged between the first pole piece and the second pole piece; wherein at least one layer of the separation film closest to the shell is a first type of separation film, the first type of separation film comprises a first film body and second and third film bodies located on both sides of the first film body in the thickness direction, the porosity of the first film body is P1, the porosity of the second film body is P2, and the porosity of the third film body is P3, and the following conditions are met: P1>P2 and P1>P3. The application can improve the impact resistance of the battery monomer, improve the mass energy density of the battery monomer, and improve the reliability of the battery monomer.

Description

Technical Field

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

[0002] Currently, excessive localized stress on electrode components under high-speed impact can lead to brittle cracking of the electrode sheets. Cracked electrodes can easily puncture the separator, causing the anode and cathode to overlap, triggering an internal short circuit and causing safety issues. One related technology involves increasing the separator thickness to improve the impact resistance of individual battery cells, but this significantly impacts the energy density and power performance of the battery cells. Utility Model Content

[0003] This application provides a battery cell, a separator, a battery device, and an electrical device to improve the impact resistance of the battery cell without affecting its energy density and power performance.

[0004] In a first aspect, embodiments of this application provide a single battery cell, comprising:

[0005] shell;

[0006] An electrode assembly is disposed within the housing. The electrode assembly includes a first electrode, a separator, and a second electrode. The separator is disposed between the first electrode and the second electrode. At least one separator closest to the housing is a first type of separator. The first type of separator includes a first membrane body and a second membrane body and a third membrane body located on both sides of the first membrane body along the thickness direction. The porosity of the first membrane body is P1, the porosity of the second membrane body is P2, and the porosity of the third membrane body is P3, satisfying: P1 > P2, P1 > P3.

[0007] In the above technical solution, by setting the base membrane of the first type of separator to a three-layer structure with a porosity gradient, the first membrane (middle layer) is a high-porosity membrane, and the second and third membranes (side layers) are low-porosity membranes. The high-porosity membrane can increase the electrolyte storage capacity, and the low-porosity membrane can increase the difficulty of electrolyte flowing out of the separator when the battery cell is impacted. Thus, the first type of separator can provide a better liquid buffering effect when the battery cell is impacted. Compared with conventional separator design, it can improve the impact resistance of the battery cell and improve the reliability of the battery cell.

[0008] In some embodiments, the electrode assembly is wound, and the porosity of the first type of separator monotonically does not increase from the outside to the inside along the winding direction.

[0009] In some embodiments, the electrode assembly is wound, and along the winding direction of the electrode assembly, the porosity of the first membrane body in the outermost region of the first type of separator is greater than the porosity of other regions of the first type of separator.

[0010] In some embodiments, the electrode assembly further includes a second type of separator, wherein the innermost end of the first type of separator is connected to the outermost end of the second type of separator along the winding direction of the electrode assembly, and the average porosity of the second type of separator is less than the average porosity of the first type of separator.

[0011] In some embodiments, the electrode assembly is a wound type, wherein the side of the first membrane facing the second membrane along the width direction is connected to the side of the second membrane along the width direction, and the side of the first membrane facing the third membrane along the width direction is connected to the side of the third membrane along the width direction.

[0012] In some embodiments, the second membrane and the third membrane protrude from the end of the first membrane along the width direction, and the side of the second membrane distributed along the width direction is connected to the side of the third membrane distributed along the width direction.

[0013] In some embodiments, the electrode assembly is a stacked type, and a plurality of the separators are spaced apart along the stacking direction, wherein the porosity of the first membrane located on the outermost layer is greater than the porosity of the first membrane located on the middle layer.

[0014] In some embodiments, the porosity of the plurality of first membranes decreases monotonically from the outermost layer to the middle layer along the stacking direction.

[0015] In some embodiments, the electrode assembly is a stacked type, with the periphery of the side of the first membrane facing the second membrane connected to the periphery of the second membrane, and the periphery of the side of the first membrane facing the third membrane connected to the periphery of the third membrane.

[0016] In some embodiments, the second membrane protrudes from the end of the first membrane in a direction perpendicular to the thickness direction, the third membrane protrudes from the end of the first membrane in a direction perpendicular to the thickness direction, and the periphery of the second membrane and the periphery of the third membrane are connected.

[0017] In some embodiments, the following conditions are met: P1-P2 > 10%, P1-P3 > 10%.

[0018] In some embodiments, the following conditions are met: 40% ≤ P1 ≤ 60%, 30% ≤ P2 ≤ 40%, and 30% ≤ P3 ≤ 40%.

[0019] In some embodiments, the second membrane and the third membrane have different thicknesses.

[0020] In some embodiments, the thickness of the first membrane is H1, the thickness of the second membrane is H2, and the thickness of the third membrane is H3, satisfying: 20% ≤ H1 / (H1+H2+H3) ≤ 40%.

[0021] In some embodiments, the thickness of the first membrane is H1, the thickness of the second membrane is H2, and the thickness of the third membrane is H3, satisfying: H2 / (H1+H2+H3)≥20%, H3 / (H1+H2+H3)≥20%.

[0022] In some embodiments, the following condition is satisfied: H2 / (H1+2H2)≥20%.

[0023] Secondly, embodiments of this application provide a separating membrane, comprising: a first membrane body and a second membrane body and a third membrane body located on both sides of the first membrane body along the thickness direction, wherein the porosity of the first membrane body is P1, the porosity of the second membrane body is P2, and the porosity of the third membrane body is P3, satisfying: P1 > P2, P1 > P3.

[0024] Thirdly, embodiments of this application provide a battery device, including: a plurality of battery cells as described in any of the above embodiments.

[0025] Fourthly, embodiments of this application provide an electrical device, including: a battery cell as described in any of the above embodiments, and a battery device as described in any of the above embodiments, wherein the battery cell or the battery device is used to store or provide electrical energy. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This application provides schematic diagrams of the structure of an energy storage system according to some embodiments.

[0028] Figure 2 This is a schematic diagram of the structure of a charging network provided in some embodiments of this application;

[0029] Figure 3 This application provides structural schematic diagrams of vehicles for some embodiments;

[0030] Figure 4Exploded views of the structure of the battery device provided in some embodiments of this application;

[0031] Figure 5 This is a schematic diagram of the structure of an electrode assembly provided in some embodiments of this application;

[0032] Figure 6 This is one of the structural schematic diagrams of the isolation membrane provided in some embodiments of this application;

[0033] Figure 7 This is a second schematic diagram of the structure of the isolation membrane provided in some embodiments of this application;

[0034] Figure 8 This is the third schematic diagram of the structure of the isolation membrane provided in some embodiments of this application.

[0035] Figure label:

[0036] Energy storage device 1, power conversion device 2, power generation device 3, charging pile 4, connector 5;

[0037] 1000 vehicles;

[0038] Battery device 100;

[0039] Box 10, first box body 11, second box body 12;

[0040] Battery cell 20, electrode assembly 21, first electrode 211, first type of separator 212, first membrane 2121, second membrane 2122, third membrane 2123, coating 2124, second electrode 213;

[0041] Controller 200; Motor 300. Detailed Implementation

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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).

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

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

[0050] Battery cells can be cylindrical, flat, cuboid, or other shapes, and this application embodiment is not limited to any of these. Battery cells are generally classified into three types according to their packaging method: cylindrical battery cells, square battery cells, and pouch battery cells, and this application embodiment is not limited to any of these types either.

[0051] A battery cell includes a casing, electrode components, and electrolyte. The casing houses the electrode components and electrolyte. The electrode components consist of a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrode components. The positive electrode includes a positive current collector and a positive active material layer. The positive current collector includes a current collector body and a positive electrode tab. The positive active material layer is coated on the surface of the current collector body, while the positive electrode tab is not coated with the positive active material layer and protrudes from the current collector body. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative active material layer. The negative current collector includes a current collector body and a negative electrode tab. The negative active material layer is coated on the surface of the current collector body, while the negative electrode tab is not coated with the negative active material layer and protrudes from the current collector body. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon or silicon, etc. To ensure that a large current can be passed without melting, there are multiple positive electrode tabs stacked together, and there are multiple negative electrode tabs stacked together.

[0052] The separator can be made of PP (polypropylene) or PE (polyethylene), etc. Furthermore, the electrode assembly can be a wound structure or a stacked structure; the embodiments of this application are not limited to these.

[0053] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft, including aircraft, rockets, space shuttles, and spacecraft. Individual battery cells are used to store or provide electrical energy.

[0054] The inventors discovered that, currently, excessive localized stress on electrode components under high-speed impact can cause brittle cracking of the electrode sheets. Cracked electrode sheets can easily puncture the separator, leading to contact between the anode and cathode, triggering an internal short circuit and causing safety issues. Related technologies have proposed increasing the separator thickness to enhance the impact resistance of individual battery cells, but this significantly impacts the energy density and power performance of the battery cells.

[0055] Based on the above considerations, in order to solve the problem of poor impact resistance of battery cells, the inventors, after in-depth research, designed a battery cell including a shell and an electrode assembly. The electrode assembly is located inside the shell and includes a first electrode, a separator, and a second electrode. The separator is located between the first electrode and the second electrode. At least the separator closest to the shell is a first type of separator. The first type of separator includes a first membrane body and a second membrane body and a third membrane body located on both sides of the first membrane body along the thickness direction. The porosity of the first membrane body is P1, the porosity of the second membrane body is P2, and the porosity of the third membrane body is P3, satisfying: P1 > P2, P1 > P3.

[0056] In this type of battery cell, a first-type separator is placed at least in the layer closest to the outer shell. The base membrane of the first-type separator is set as a three-layer structure with a porosity gradient. The first membrane (middle layer) is a high-porosity membrane, and the second membrane (side layers) is a low-porosity membrane. The high-porosity membrane can increase the electrolyte storage capacity, and the low-porosity membrane can increase the difficulty of electrolyte flowing out of the separator when the first-type separator is impacted. Thus, the first-type separator can provide a better liquid buffering effect. Compared with conventional separator designs, it can improve the impact resistance of the battery cell, increase the mass energy density of the battery cell, and improve the reliability of the battery cell.

[0057] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0058] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0059] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0060] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0061] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0062] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0063] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0064] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0065] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0066] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use battery devices, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft. The battery device is used to store or provide electrical energy.

[0067] This application provides an energy storage device including one or more battery clusters to increase the voltage and capacity of the energy storage device. The battery cluster may include multiple battery devices, which are connected in series via a busbar to increase the voltage of the energy storage device. When the energy storage device includes multiple battery clusters, the multiple battery clusters are connected in parallel to increase the capacity of the energy storage device.

[0068] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, an energy storage device can store electrical energy during off-peak hours and provide power to relevant users or electrical devices during peak hours. The energy storage system provided in this application embodiment can be any power system that requires energy storage devices.

[0069] In some embodiments, the energy storage device is an energy storage container or an energy storage cabinet.

[0070] In some embodiments, the energy storage device may include a cabinet and one or more battery clusters housed within the cabinet.

[0071] In some embodiments, the energy storage device may include modules such as a thermal management module, a main control module, a central control module, a power distribution module, and a fire protection module.

[0072] As an example, the thermal management module may include a liquid cooling unit that supplies coolant to each battery device via piping to regulate the temperature of the individual battery cells.

[0073] As an example, the main control module can serve as the battery management unit for the battery cluster, used to monitor and manage the battery cluster. The main control module can monitor information such as the current, voltage, power, or temperature of the battery cluster. For instance, it can control the charging and discharging current and voltage of the battery cluster. The main control module includes modules such as an auxiliary battery management unit (SBMU) and a fusion switch.

[0074] As an example, the central control module can serve as the battery management unit for an energy storage device, used to monitor and manage the device. The central control module can monitor information such as the energy storage device's current, voltage, power, state of charge, or temperature. For instance, it can control the charging and discharging current and voltage of the energy storage device. As an example, the central control module includes modules such as an Insulation Monitoring Module (IMM), a Master Battery Management Unit (MBMU), an Ethernet (ETH) module, and a fiber optic conversion module.

[0075] As an example, a fire protection system includes control panels, detectors, alarm devices, etc., used to detect, alarm, or extinguish fires in energy storage systems.

[0076] As an example, the power distribution unit can be used to distribute power to the power modules of the energy storage device.

[0077] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use energy storage devices, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft. The energy storage device is used to store or provide electrical energy.

[0078] In some embodiments, such as Figure 1As shown, the energy storage system may include one or more energy storage devices 1 and a power converter system (PCS), wherein the power converter system 2 is used to connect the power generation device 3 and the energy storage device 1. The power generation device 3 is used to generate electrical energy, and the electrical energy generated by the power generation device 3 can be stored in the energy storage device 1 through the power converter system 2. As an example, the power generation device 3 may specifically be a solar panel, a hydroelectric power generation device, a thermal power generation device, a wind power generation device, etc. The specific type of the power generation device 3 is not limited in this application.

[0079] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use energy storage systems, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft, including aircraft, rockets, space shuttles, and spacecraft. Energy storage devices are used to store or provide electrical energy.

[0080] Please refer to Figure 2 This application provides a charging network including a charging pile 4 and an energy storage device 1. The charging pile 4 is electrically connected to the energy storage device 1, and the energy storage device 1 provides electrical energy to the charging pile 4. The charging pile 4 is electrically connected to a battery device in the energy storage device 1 via a cable, and the battery device can provide its stored electrical energy to the charging pile 4. The charging pile 4 has one or more connectors 5, which are used to connect to electrical devices (such as vehicles) to replenish energy to the electrical devices.

[0081] Energy storage devices can be located inside the charging pile (e.g., an integrated energy storage and charging unit) or outside the charging pile.

[0082] This application provides an electrical device that uses a single battery cell, battery device, energy storage device, or energy storage system as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, and spacecraft. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft.

[0083] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.

[0084] Please refer to Figure 3 , Figure 3This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle, etc. A battery device 100 is installed inside the vehicle, and the battery device 100 can be located at the bottom, front, or rear of the vehicle. The battery device 100 can be used to power the vehicle; for example, the battery device 100 can serve as the vehicle's operating power source. The vehicle may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle during starting, navigation, and driving.

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

[0086] Please refer to Figure 4 , Figure 4 This is an exploded view of the structure of a battery device 100 provided in some embodiments of this application. The battery device 100 includes a housing 10 and a plurality of battery cells 20, which are housed within the housing 10. The housing 10 provides assembly space for the battery cells 20, and the housing 10 can adopt various structures. In some embodiments, the housing 10 may include a first housing body 11 and a second housing body 12, which overlap each other, and together define an assembly space for accommodating the battery cells 20. The second housing body 12 may be a hollow structure open at one end, and the first housing body 11 may be a plate-like structure, with the first housing body 11 covering the open side of the second housing body 12, so that the first housing body 11 and the second housing body 12 together define the assembly space; alternatively, the first housing body 11 and the second housing body 12 may both be hollow structures open on one side, with the open side of the first housing body 11 covering the open side of the second housing body 12. Of course, the box 10 formed by the first box body 11 and the second box body 12 can be of various shapes, such as cylinder, cuboid, etc.

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

[0088] Please refer to Figure 4 , Figure 4 This is a partial structural schematic diagram of a battery device 100 provided in some embodiments of this application. The battery device 100 includes multiple rows of battery cells 20, which are arranged along a first direction. Each row of battery cells 20 includes multiple battery cells 20 arranged along a second direction. The first direction and the second direction are the length direction and the width direction of the housing 10, respectively, and the first direction and the second direction are perpendicular to each other.

[0089] According to some embodiments of this application, refer to Figure 5 This application provides a battery cell 20.

[0090] The battery cell 20 in this embodiment includes: a housing and an electrode assembly 21, wherein the electrode assembly 21 is disposed inside the housing, as shown in the reference. Figure 6 The electrode assembly 21 includes a first electrode 211, a separator, and a second electrode 213, with at least a portion of the separator disposed between the first electrode 211 and the second electrode 213.

[0091] The separator is located between the first electrode 211 and the second electrode 213 to isolate the first electrode 211 and the second electrode 213. When the battery cell 20 is impacted and the separator between the first electrode 211 and the second electrode 213 breaks, it will cause a short circuit between the first electrode 211 and the second electrode 213, and the battery cell 20 will fail.

[0092] Reference Figure 7 and Figure 8 At least the layer of the isolation membrane closest to the outer shell is a first type of isolation membrane 212. The first type of isolation membrane 212 includes a first membrane body 2121 and a second membrane body 2122 and a third membrane body 2123 located on both sides of the first membrane body 2121 along the thickness direction. The porosity of the first membrane body 2121 is P1, the porosity of the second membrane body 2122 is P2, and the porosity of the third membrane body 2123 is P3, satisfying: P1 > P2, P1 > P3.

[0093] Among them, one of the first electrode 211 and the second electrode 213 is a positive electrode, and the other of the first electrode 211 and the second electrode 213 is a negative electrode.

[0094] In this embodiment, the electrode assembly 21 can be a wound structure or a stacked structure, and the embodiments of this application are not limited thereto.

[0095] Among them, reference Figure 7 The electrode assembly 21 includes a first type of separator 212, which includes a base film and coatings 2124 disposed on both sides of the base film in the thickness direction. The base film is a composite structure of three layers, and the base film includes a second film 2122, a first film 2121 and a third film 2123 in sequence along the thickness direction.

[0096] The types of the first membrane 2121, the second membrane 2122, and the third membrane 2123 can be the same or different, and the embodiments of this application are not limited thereto.

[0097] For example, the type of the first membrane 2121 includes, but is not limited to, polyethylene (PE), polypropylene (PP), and nonwoven membrane (polyimide, aramid).

[0098] For example, the types of the second membrane 2122 and the third membrane 2123 include, but are not limited to, polyethylene (PE), polypropylene (PP), and nonwoven membranes (polyimide, aramid).

[0099] The porosity P1 of the first membrane 2121 is greater than the porosity P2 of the second membrane 2122, that is, the first membrane 2121 and the second membrane 2122 form a porosity gradient; the porosity P1 of the first membrane 2121 is greater than the porosity P3 of the third membrane 2123, that is, the first membrane 2121 and the third membrane 2123 form a porosity gradient.

[0100] In other words, the first membrane 2121 of the middle layer is designed as a high-porosity membrane, while the second membrane 2122 and the third membrane 2123 of the two side layers are designed as low-porosity membranes with a porosity lower than that of the first membrane 2121.

[0101] It should be noted that the second membrane 2122 and the third membrane 2123 can be of normal porosity, that is, the second membrane 2122 and the third membrane 2123 can be porous membranes that allow lithium ions to shuttle normally in related technologies.

[0102] The porosity of the first membrane 2121 is greater than that of the second membrane 2122 and the third membrane 2123. That is, the porosity of the first membrane 2121 is greater than the normal porosity, so it will not affect the shuttle of lithium ions in the first type of separator.

[0103] After the battery cell 20 is immersed in electrolyte at high temperature, the electrolyte fills the pores of the separator. In this embodiment, the three layers of the base membrane have different porosities, forming a porosity gradient. The first membrane 2121 (middle layer) is a high-porosity membrane, while the second membrane 2122 and the third membrane 2123 (side layers) are low-porosity membranes. In this structural design, the first membrane 2121 (middle layer) is a high-porosity membrane, while the second membrane 2122 and the third membrane 2123 (side layers) have normal porosity. The first membrane 2121 (high-porosity membrane) has a better electrolyte absorption capacity than the second membrane 2122 and the third membrane 2123 (low-porosity membrane). The pores of the first membrane 2121 have a stronger electrolyte storage capacity (absorb more electrolyte). Compared with a separator of the same thickness and normal porosity, this design can absorb more electrolyte.

[0104] When the battery cell 20 is subjected to a high-speed impact, the electrode assembly 21 is squeezed. At this time, the electrolyte in the pores of the first type of separator 212 dissipates energy due to the squeezed flow, thus playing a liquid buffering role. On the one hand, the first type of separator 212 of this application absorbs more electrolyte than a normal porosity separator of the same thickness. Therefore, the greater electrolyte flow dissipates the absorbed energy, thus playing a liquid buffering role. On the other hand, since the first membrane 2121 (intermediate layer) has a high porosity and absorbs more liquid, and there is a porosity gradient between the high porosity membrane and the normal porosity membranes on both sides, when the first type of separator 212 is squeezed, the electrolyte in the first membrane 2121 (intermediate layer) will have more difficulty passing through the second membrane 2122 and the third membrane 2123 due to the storage capacity and porosity gradient. That is, more energy is required to squeeze the electrolyte flow out of the first membrane 2121, thus dissipating more energy and providing a better liquid buffering effect. Compared to conventional separator designs, this composite first-class separator 212 design has stronger structural strength and mechanical properties, which can improve the impact resistance of the battery cell 20.

[0105] Furthermore, when the battery cell 20 is subjected to a high-speed impact, the side of the electrode assembly 21 closest to the outer shell is the first to be squeezed and subjected to the greatest force. The first type of separator 212 is set as the separator closest to the outer shell. When the battery cell 20 is subjected to an external impact, the first type of separator 212 can effectively resist and absorb the impact energy, thereby reducing the direct transmission of impact energy to the inside of the electrode assembly 21.

[0106] Among them, the first type of separator 212 can be provided in one or more layers closest to the outer shell and along the winding direction to improve the impact resistance of the battery cell 20. When the battery cell 20 is impacted by an external force from the thickness direction, the high mechanical strength and liquid buffering performance of the first type of separator 212 can effectively dissipate energy, thereby helping to reduce the risk of short circuit when the battery cell 20 is impacted by an external force.

[0107] Among them, the electrode assembly 21 is a wound type, and the wound structure includes straight areas and bent areas that are connected in sequence and alternately arranged.

[0108] When the battery cell 20 has an electrode assembly 21, when the large surface (i.e. the front) of the battery cell 20 is subjected to an external force impact, by providing a first type of separator 212 in the flat area corresponding to the large surface of the electrode assembly 21, the higher mechanical strength and deformation volume of the first type of separator 212 can buffer the external force impact from the large surface; in addition, by providing a first type of separator 212 in the bending area, the external force impact from the side (e.g., the length direction of the battery cell 20) can be buffered, thereby further reducing the risk of short circuit when the battery cell 20 is subjected to an external force impact.

[0109] When the battery cell 20 has multiple electrode assemblies 21, the multiple electrode assemblies 21 are stacked along the first direction and the second direction. A first type of separator 212 is provided in the electrode assembly 21 closest to the outer casing. When the outer casing of the battery cell 20 is impacted by an external force, the impact from the external force can be buffered by providing the first type of separator 212 in the electrode assembly 21 closest to the outer casing. This helps to further reduce the risk of short circuit when the battery cell 20 is impacted by an external force, and can also reduce costs and increase energy density.

[0110] For example, the electrode assembly 21 is in a single row and stacked along the thickness direction. The flat area facing the outer shell and the bending area on both sides of the flat area in the electrode assembly 21 at both ends are set as the first type of separator 212. The first type of separator 212 is only set in the bending area facing the outer shell in the electrode assembly 21 in the middle, which is beneficial to achieving a balance between the safety performance and energy density of the battery cell 20.

[0111] Among them, the first type of separator 212 is disposed in the region closest to the outer shell among the multiple electrode components 21 closest to the outer shell. It can buffer the impact of external force from the outer shell, thereby helping to further reduce the risk of short circuit when the battery cell 20 is subjected to external force impact, reduce the impact energy directly transferred to the internal electrode components 21, and improve the impact resistance and reliability of the battery cell.

[0112] In some embodiments, the separator further includes an extension section extending beyond the first electrode 211 or the second electrode 213 along the winding direction, wherein the extension section has a winding number of turns greater than 0 along the winding direction.

[0113] Along the winding direction, the extension section can have 2, 3 or more turns. By adding an extension section that extends beyond the outer end of the first electrode 211 or the second electrode 213, the extension section can reduce the direct transfer of impact energy to the electrode assembly when the battery cell 20 is impacted. This provides sufficient physical barrier and electrochemical isolation for the first electrode 211 or the second electrode 213, ensuring that the outer end of the first electrode 211 or the second electrode 213 is not directly exposed to the electrolyte or other environments that may cause short circuits or damage. At the same time, it can also restrain the outer end of the first electrode 211 or the second electrode 213, increasing the impact resistance of the battery cell 20 and extending its service life.

[0114] The electrode assembly 21 includes at least the following two structures:

[0115] Firstly, the electrode assembly 21 is of the wound type.

[0116] The insulating membrane of the wound electrode assembly 21 includes at least the following two structures:

[0117] First, the separator of the electrode assembly 21 may consist only of a first type of separator 212, which extends from the inside to the outside along the winding direction.

[0118] In some embodiments, the porosity of the first type of separator 212 does not increase monotonically from the outside to the inside along the winding direction.

[0119] The porosity of the first type of isolation membrane 212 can be the average porosity of the first membrane 2121, the second membrane 2122 and the third membrane 2123 in the first type of isolation membrane 212, or it can be the porosity of the first membrane 2121.

[0120] For example, the porosity of the first type of separator 212 remains unchanged. The porosity of the first type of separator 212 remains unchanged from the outside to the inside along the winding direction, which improves the impact resistance and reduces the assembly difficulty of the electrode assembly 21.

[0121] For example, the porosity of the first type of separator 212 gradually decreases from the outside to the inside along the winding direction, that is, the average porosity of the first type of separator 212 or the porosity of the first membrane 2121 gradually decreases from the outside to the inside along the winding direction, which further improves the impact resistance and increases the energy density.

[0122] For example, the porosity of the first type of separator 212 gradually decreases from the outside to the inside along the winding direction and then remains constant. That is, the average porosity of the first type of separator 212 or the porosity of the first membrane 2121 gradually decreases from the outside to the inside along the winding direction and then remains constant, thereby improving impact resistance.

[0123] It is understandable that porosity is measured by instruments or experiments. In reality, the pores of a membrane are not uniform along the thickness direction. The measured porosity result already includes the error in the distribution of pores. That is, the measured porosity data is the average porosity of the membrane.

[0124] The following provides a method for calculating the average porosity of a first-type separating membrane 212:

[0125] The thickness of the first membrane 2121 is H1, the thickness of the second membrane 2122 is H2, the thickness of the third membrane 2123 is H3, the total thickness of the first type of separator 212 is X, the porosity of the first membrane 2121 is P1, the porosity of the second membrane 2122 is P2, and the porosity of the third membrane 2123 is P3.

[0126] The total thickness X of the first type of separator 212 satisfies: X = H1 + H2 + H3;

[0127] The average porosity P of the first type of separator 212 satisfies: P=P1*(H1 / X)+P2*(H2 / X)+P3*(H3 / X).

[0128] In some embodiments, the electrode assembly 21 is a wound type, and along the winding direction of the electrode assembly 21, the porosity of the first membrane 2121 in the outermost region of the first type of separator 212 is greater than the porosity of other regions of the first type of separator 212.

[0129] Among them, the porosity of the first membrane 2121 in the outermost region of the first type of isolation membrane 212 is greater than the porosity of other regions of the first membrane 2121.

[0130] In this embodiment, the outermost region of the first type of separator 212 is the region most susceptible to impact damage. Setting the porosity of the first membrane 2121 in the outermost region of the first type of separator 212 to the maximum porosity can reduce the risk of the electrode assembly 21 being damaged by impact and improve its impact resistance.

[0131] Second, the separator of the electrode assembly 21 may include a first type of separator 212 and a second type of separator. Along the winding direction of the electrode assembly 21, the innermost end of the first type of separator 212 is connected to the outermost end of the second type of separator. The average porosity of the second type of separator is less than the average porosity of the first type of separator 212.

[0132] For example, the second type of separator can be a common separator in the related art, or it can be a separator with an average porosity that is less than that of the first type of separator 212.

[0133] The first type of separator 212 has a stronger liquid buffering capacity than the second type of separator. Along the winding direction of the electrode assembly 21, the first type of separator 212 is positioned closer to the outer shell than the second type of separator, which can improve the resistance of the electrode assembly 21 to external impact, thereby reducing the risk of short circuit when the battery cell 20 is subjected to external impact.

[0134] In this embodiment, the outer casing serves as the direct interface through which the battery cell 20 withstands external impacts. When the battery cell 20 is subjected to an external impact, the impact energy is easily transferred through the outer casing to the adjacent electrode assembly 21. By providing a first-type separator 212 in the region of the electrode assembly 21 adjacent to the outer casing, the first-type separator 212 possesses higher mechanical strength and deformation volume. When the battery cell 20 is subjected to an external impact, the first-type separator 212 can more effectively resist and absorb the impact energy due to its own strength and deformation capacity, thereby reducing the direct transfer of impact energy to the interior. This design can reduce the probability of brittle cracking of the first electrode 211 and the second electrode 213 due to impact, thereby reducing the risk of short circuit in the battery cell 20. Furthermore, providing a second-type separator in the interior region away from the outer casing, where the impact risk is lower, can reduce the impact on the battery energy density and is beneficial for maintaining the good electrochemical performance of the battery cell 20.

[0135] For example, the innermost end of the first type of separator 212 and the outermost end of the second type of separator may have an overlapping area to reduce processing difficulty and reduce the risk of short circuit caused by the formation of a gap between the innermost end of the first type of separator 212 and the outermost end of the second type of separator.

[0136] In some embodiments, such as Figure 7 As shown, the electrode assembly 21 is a wound type. The side of the first membrane 2121 facing the second membrane 2122 along the width direction is connected to the side of the second membrane 2122 along the width direction. The side of the first membrane 2121 facing the third membrane 2123 along the width direction is connected to the side of the third membrane 2123 along the width direction.

[0137] The second membrane 2122 is connected to the side of the third membrane 2123 along the width direction via the first membrane 2121, thereby sealing the side of the first type of isolation membrane 212 along the width direction.

[0138] In some embodiments, such as Figure 8As shown, the second membrane 2122 and the third membrane 2123 protrude from the end of the first membrane 2121 along the width direction, and the side of the second membrane 2122 distributed along the width direction is connected to the side of the third membrane 2123 distributed along the width direction.

[0139] The second membrane 2122 is directly connected to the side of the third membrane 2123 along the width direction, thereby sealing the side of the first type of isolation membrane 212 along the width direction and reducing the volume of both ends of the electrode assembly 21 along the width direction.

[0140] In this embodiment, the first type of separator 212 is closed along the side in the width direction. When subjected to external impact, it can reduce the leakage of electrolyte from the side wall of the first type of separator 212 in the width direction, thereby having a stronger liquid buffering effect and further improving the impact resistance of the battery cell 20.

[0141] Secondly, when the electrode assembly 21 is a stacked type, the first type of separator 212 is arranged sequentially along the stacking direction.

[0142] The insulating membrane of the wound electrode assembly 21 includes at least the following two structures:

[0143] First, the electrode assembly 21 is a stacked type, and the separator of the electrode assembly 21 may only include the first type of separator 212. Multiple first type separators 212 are distributed at intervals along the stacking direction to improve the impact resistance of the battery cell 20.

[0144] In some embodiments, a plurality of first-type isolation membranes 212 are spaced apart along a stacking direction, wherein the porosity of the first membrane 2121 located in the outermost layer is greater than that of the first membrane 2121 located in the middle layer.

[0145] In this embodiment, the part closest to the large surface of the outer shell along the stacking direction is the area most susceptible to impact damage. Setting the first membrane 2121 located on the outermost layer to have the largest porosity can reduce the risk of the electrode assembly 21 being damaged by impact and improve its impact resistance.

[0146] In some embodiments, the porosity of the plurality of first membranes 2121 remains monotonically constant from the outermost layer to the middle layer along the stacking direction.

[0147] For example, the porosity of the first membrane 2121 remains unchanged, and the porosity of the first membrane 2121 remains unchanged from the outside to the inside along the stacking direction, thereby improving impact resistance and reducing assembly difficulty.

[0148] For example, the porosity of the plurality of first membranes 2121 decreases monotonically from the outermost layer to the middle layer along the stacking direction, further improving impact resistance and increasing energy density.

[0149] For example, the porosity of the plurality of first membranes 2121 gradually decreases from the outside to the inside along the stacking direction and then remains constant. That is, the average porosity of the first type of isolation membrane 212 or the porosity of the first membrane 2121 gradually decreases from the outside to the inside along the winding direction and then remains constant, thereby improving impact resistance.

[0150] Second, the isolation membrane of the electrode assembly 21 may include a first type of isolation membrane 212 and a second type of isolation membrane. Along the stacking direction of the electrode assembly 21, a plurality of first type of isolation membranes 212 and a plurality of second type of isolation membranes are distributed along the stacking direction, with the first type of isolation membranes 212 distributed along the stacking direction at the outer ends of the plurality of second type of isolation membranes.

[0151] In this embodiment, the outer casing serves as the direct interface through which the battery cell 20 withstands external impacts. When the battery cell 20 is impacted along its thickness, the impact energy is easily transferred through the outer casing to the adjacent electrode assembly 21. By providing a first-type separator 212 in the region of the electrode assembly 21 adjacent to the outer casing, the first-type separator 212 possesses higher mechanical strength and deformation volume. When the battery cell 20 is impacted, the first-type separator 212 can more effectively resist and absorb the impact energy due to its own strength and deformation capacity, thereby reducing the direct transfer of impact energy to the interior. This design reduces the probability of brittle fracture of the first electrode 211 and the second electrode 213 due to impact, thereby reducing the risk of short circuit in the battery cell 20. Furthermore, providing a second-type separator in the interior region, away from the outer casing, where the impact risk is lower, can reduce the impact on the battery energy density and is beneficial for maintaining the good electrochemical performance of the battery cell 20.

[0152] In some embodiments, such as Figure 7 As shown, the electrode assembly 21 is a stacked type, with the periphery of the side of the first membrane 2121 facing the second membrane 2122 connected to the periphery of the second membrane 2122, and the periphery of the side of the first membrane 2121 facing the third membrane 2123 connected to the periphery of the third membrane 2123.

[0153] The periphery of the second membrane 2122 is the edge of the second membrane 2122, and the periphery of the third membrane 2123 is the edge of the third membrane 2123.

[0154] In this embodiment, the periphery of the second membrane 2122 is connected to the periphery of the third membrane 2123 through the first membrane 2121, thereby sealing the side of the first type of isolation membrane 212 along the width direction.

[0155] In some embodiments, such as Figure 8As shown, the second membrane 2122 protrudes from the end of the first membrane 2121 in a direction perpendicular to the thickness direction, and the third membrane 2123 protrudes from the end of the first membrane 2121 in a direction perpendicular to the thickness direction. The periphery of the second membrane 2122 and the periphery of the third membrane 2123 are connected.

[0156] The periphery of the second membrane 2122 protrudes beyond the periphery of the first membrane 2121, and the periphery of the third membrane 2123 protrudes beyond the periphery of the first membrane 2121. The periphery of the second membrane 2122 is directly connected to the periphery of the third membrane 2123, thereby sealing the periphery of the first type of isolation membrane 212, reducing the volume of the periphery of the electrode assembly 21, and increasing the energy density.

[0157] In this embodiment, the periphery of the first type of separator 212 is sealed, which can reduce the leakage of electrolyte from the periphery of the first type of separator 212 when subjected to external impact, thereby having a stronger liquid buffering effect and further improving the impact resistance of the battery cell 20.

[0158] It should be noted that, compared with separators of the same thickness, the first membrane 2121 (intermediate layer) in the first type of separator 212 of this application has high porosity. High porosity means that the mass of the membrane will be reduced under the same volume, thereby reducing the mass of the separator under the same volume, which can improve the mass energy density of the battery cell 20.

[0159] Because high-porosity membranes absorb and store more electrolyte, their thermal conductivity is better than that of ordinary porous membranes, which can further improve the thermal conductivity of the first type of separator and improve the uniformity of temperature distribution of the battery cell 20 during normal charging and discharging.

[0160] High-porosity membranes are more conducive to storing electrolytes, thus improving the power performance of the battery cell 20. For example, the ions can be lithium ions or sodium ions, depending on the type of battery cell 20.

[0161] In related technologies, a solution has emerged that improves the impact resistance of the battery cell 20 by increasing the thickness of the separator, but this significantly affects the energy density and power performance of the battery cell 20. This application, without changing the separator thickness, sets the base film to a three-layer structure. The total thickness of the first film 2121 and the two second films 2122 on both sides is similar to or the same as the total thickness of a conventional single-layer base film for the separator. This can improve the impact resistance limit of the battery cell 20 without affecting its energy density and power performance, thereby increasing the reliability of the battery cell 20.

[0162] In related technologies, a three-layer base membrane separator structure has also emerged. To improve ion transport efficiency, the separator is designed with a porosity greater than that of the middle layer on both sides. However, this structure increases the thickness of the separator, reducing the energy density of the battery cell 20. Furthermore, with this approach, when the separator is compressed, the electrolyte is easily squeezed out of the separator because the porosity of the two sides is greater than that of the middle layer, making it impossible to store a certain amount of electrolyte in the middle layer to achieve a liquid buffering effect.

[0163] Since ion transport efficiency is positively correlated with the porosity of the membrane, in related technologies, to avoid affecting ion transport efficiency, the base membrane of the multilayer membrane structure is generally not designed with a porosity gradient. Even if a porosity gradient is set, the porosity gradient of the multilayer membrane will increase from the inside to the outside, with the porosity of the outer membrane being greater than that of the inner membrane, in order to improve ion transport efficiency.

[0164] If the base membrane is set as a multilayer membrane with a porosity gradient that decreases from the inside to the outside, the outer membrane will hinder ion transport in the electrolyte of the inner membrane, which will affect the ion transport efficiency.

[0165] In the first type of separating membrane 212 of this application, the porosity of the inner first membrane 2121 is set to be greater than that of the outer second membrane 2122 and third membrane 2123, while the porosity of the outer second membrane 2122 and third membrane 2123 is the normal porosity. This allows ions to pass normally through the first membrane 2121, second membrane 2122, and third membrane 2123, and the pores within the first membrane 2121, second membrane 2122, and third membrane 2123 are also filled with ions. Both membranes store electrolyte. Since the porosity of the second membrane 2122 and the third membrane 2123 is less than that of the first membrane 2121, the first membrane 2121 stores more electrolyte in its pores. When subjected to impact or compression, the second membrane 2122 and the third membrane 2123 will restrict the outflow of electrolyte from the pores of the first membrane 2121. The electrolyte in the pores of the first membrane 2121 will act as a liquid buffer, thereby improving the impact resistance of the separator.

[0166] According to the battery cell 20 provided in the embodiments of this application, by setting the base membrane of the first type of separator to a three-layer structure with a porosity gradient, the first membrane 2121 (middle layer) is a high-porosity membrane, and the second membrane 2122 and the third membrane 2123 (side layers) are low-porosity membranes. The high-porosity membrane can increase the electrolyte storage capacity, and the low-porosity membrane can increase the difficulty of electrolyte flowing out of the separator when the battery cell 20 is impacted. Thus, the first type of separator can provide a better liquid buffering effect when the battery cell 20 is impacted. Compared with conventional separator design, it can improve the impact resistance of the battery cell 20 and improve the reliability of the battery cell 20, thereby helping to reduce the risk of short circuit when the battery cell 20 is impacted by external force.

[0167] In some embodiments, refer to Figure 6 The separator also includes a coating 2124, which is disposed on the side of the second membrane 2122 and the third membrane 2123 away from the first membrane 2121.

[0168] In this embodiment, the first type of separator membrane includes, in sequence along the thickness direction, a coating 2124, a second membrane 2122, a first membrane 2121, a third membrane 2123, and a coating 2124.

[0169] For example, coating 2124 includes, but is not limited to, ceramic coating 2124 and polymer coating 2124. Ceramic coating 2124 includes alumina, silicon dioxide, and titanium dioxide, etc. Polymer coating 2124 includes polyvinylidene fluoride (PVDF) and polymethyl methacrylate (PMMA), etc.

[0170] The coating 2124 can improve the thermal stability of the separator, enhance electrolyte affinity, and reduce the oxidation of the separator.

[0171] For example, when the coating 2124 is a ceramic coating 2124, the ceramic coating 2124 can suppress the shrinkage of the separator at high temperature, prevent thermal runaway, and improve thermal stability; when the coating 2124 is a polymer coating 2124, it can improve electrolyte wettability, accelerate lithium ion migration, and enhance electrolyte affinity.

[0172] According to some embodiments of this application, the following conditions are met: P1-P2 > 10%, P1-P3 > 10%.

[0173] For example, P1-P2 can be 11%, 13%, 15%, 20% or greater, and P1-P3 can be 11%, 13%, 15%, 20% or greater.

[0174] In this embodiment, the difference in porosity between the first membrane 2121 and the second membrane 2122 is greater than 10%, and the difference in porosity between the first membrane 2121 and the third membrane 2123 is also greater than 10%. This further increases the difficulty of the electrolyte being squeezed out of the first type of separator, requiring more energy to expel this portion of the electrolyte. Therefore, the first type of membrane can dissipate more energy and provide a better liquid buffering effect. Compared to conventional separator designs, this porosity gradient design can further improve the impact resistance of the battery cell 20.

[0175] Table 1. Experimental data on the relationship between porosity gradient and impact strength of individual battery cells.

[0176] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 Example 2 Example 3 P1-P2 (%) -10 0 5 10 11 15 30 Impact resistance energy (J) 6 7 7.2 7.5 8 10 12.5

[0177] As can be seen from Table 1, the impact energy that the first type of separator 212 can withstand is directly proportional to the difference between P1 and P2. The larger the value of P1-P2, the greater the impact energy that the first type of separator 212 can withstand.

[0178] The test method for the impact energy boundary is as follows:

[0179] It uses 20 ternary soft-pack battery cells with a capacity of 2.0Ah and a fully charged battery.

[0180] Uses a 10kg ball head with a diameter of 25mm, and the ball head is insulated.

[0181] Different heights (energy) are thrown at the center of the large surface of the battery cell 20 to monitor the positive and negative electrode voltage and the temperature of the large surface of the battery cell 20;

[0182] Judgment criteria: The boundary of impact energy resistance is defined as no fluctuation in cell voltage and no change in surface temperature within 30 minutes after the ball drops.

[0183] According to some embodiments of this application, the following conditions are met: 40% ≤ P1 ≤ 60%, 30% ≤ P2 ≤ 40%, and 30% ≤ P3 ≤ 40%.

[0184] The porosity P2 of the second membrane 2122 and the porosity P3 of the third membrane 2123 can be equal or unequal, as long as they can form a porosity gradient with the porosity P1 of the first membrane 2121.

[0185] For example, the porosity P1 of the first membrane 2121 can be 40%, and the porosity P2 and P3 of the second membrane 2122 can be 30%; or, the porosity P1 of the first membrane 2121 can be 45%, the porosity P2 of the second membrane 2122 can be 33%, and the porosity P3 of the third membrane 2123 can be 35%; or, the porosity P1 of the first membrane 2121 can be 55%, the porosity P2 of the second membrane 2122 can be 35%, and the porosity P3 of the third membrane 2123 can be 31%; or, the porosity P1 of the first membrane 2121 can be 60%, the porosity P2 of the second membrane 2122 can be 40%, and the porosity P3 of the third membrane 2123 can be 31%.

[0186] In this embodiment, by setting the ranges of the porosity P1 of the first membrane 2121, the porosity P2 of the second membrane 2122, and the porosity P3 of the third membrane 2123, the permeability of ions is not affected, and a porosity gradient is formed to restrict the flow of electrolyte, thus providing a better liquid buffering effect.

[0187] In some embodiments, the thicknesses of the two second membranes 2122 can be the same or different, as long as the porosity gradient of the three-layer structure can be guaranteed. The specific settings can be made according to the actual situation.

[0188] According to some embodiments of this application, the two second membranes 2122 located on both sides of the first membrane 2121 have different thicknesses to adapt to various application scenarios.

[0189] For example, the thickness ratios of the second membrane 2122, the first membrane 2121, and the second membrane 2122 along the thickness direction can be 40%, 20%, and 40% respectively; or, the thickness ratios of the second membrane 2122, the first membrane 2121, and the second membrane 2122 along the thickness direction can be 20%, 40%, and 40% respectively.

[0190] According to some embodiments of this application, the two second membranes 2122 located on both sides of the first membrane 2121 have the same thickness to reduce processing difficulty.

[0191] According to some embodiments of this application, refer to Figure 6 and Figure 7 The thickness of the first membrane 2121 is H1, the thickness of the second membrane 2122 is H2, and the thickness of the third membrane 2123 is H3, satisfying: 20% ≤ H1 / (H1+H2+H3) ≤ 40%.

[0192] For example, H1 can account for 20%, 25%, 30%, 35%, or 40% of the total thickness.

[0193] For example, the thickness H1 of the first membrane 2121 accounts for 20% of the total thickness of the base membrane, and the sum of the thickness H2 of the second membrane 2122 and the thickness H3 of the third membrane 2123 accounts for 80% of the total thickness of the base membrane; or, the thickness H1 of the first membrane 2121 accounts for 30% of the total thickness of the base membrane, and the sum of the thickness H2 of the second membrane 2122 and the thickness H3 of the third membrane 2123 accounts for 70% of the total thickness of the base membrane.

[0194] In this embodiment, H1+H2+H3 represents the total thickness of the base membrane in the first type of separator 212. By setting the ratio of the first membrane 2121 with high porosity to the total thickness of the base membrane, the liquid absorption capacity of the first membrane 2121 can be increased, and the impact on the toughness and strength of the first type of separator 212 can be reduced.

[0195] Table 2. Test data on the relationship between the proportion of the first membrane 2121 in the total thickness of the base film and the impact resistance of the battery cell.

[0196]

[0197] As shown in Table 2, the ratio of the impact resistance energy of the battery cell 20 to the total thickness of the first film 2121 in the base film shows a trend of first increasing and then decreasing. The impact resistance energy that the battery cells 20 with H1 / (H1+H2+H3)<20% and H1 / (H1+H2+H3)>40% can withstand is less than the impact resistance energy that the battery cells 20 with 20%≤H1 / (H1+H2+H3)≤40% can withstand.

[0198] As shown in Table 2, when the porosity P1 of the first membrane 2121 is 50%, the porosity P2 of the second membrane 2122 and the porosity P3 of the third membrane 2123 are both 30%, the liquid absorption of the first type of isolation membrane 212 is directly proportional to the ratio of the first membrane 2121 to the total thickness of the base membrane.

[0199] In summary, considering both impact resistance and liquid absorption capacity, the limit is set at 20% ≤ H1 / (H1+H2+H3) ≤ 40%.

[0200] According to some embodiments of this application, refer to Figure 6 and Figure 7 The thickness of the first membrane 2121 is H1, the thickness of the second membrane 2122 is H2, and the thickness of the third membrane 2123 is H3, satisfying: H2 / (H1+H2+H3)≥20%, H3 / (H1+H2+H3)≥20%.

[0201] For example, the thickness of the second membrane 2122 can be 20%, 25%, 30%, 40% or more of the total thickness of the base membrane, and the thickness of the third membrane 2123 can be 20%, 25%, 30%, 40% or more of the total thickness of the base membrane.

[0202] In this embodiment, the thickness of the second membrane 2122 or the third membrane 2123 should be at least greater than or equal to 20% of the total thickness of the base membrane in order to increase the liquid absorption capacity of the first type of isolation membrane 212 and also increase the strength of the entire first type of isolation membrane 212.

[0203] Table 3. Test data on the relationship between the proportion of the second membrane 2122 in the total thickness of the base membrane and the impact strength of the battery cell.

[0204]

[0205] As shown in Table 3, the impact resistance energy of the battery cell 20 shows a monotonic trend as the ratio of the second membrane 2122 to the total thickness of the base membrane increases; when the porosity P1 of the first membrane 2121 is 50%, the porosity P2 of the second membrane 2122 and the porosity P3 of the third membrane 2123 are both 30%, the liquid absorption of the first type of separator 212 is inversely proportional to the ratio of the second membrane 2122 to the total thickness of the base membrane.

[0206] In summary, considering both impact resistance and liquid absorption capacity, the following settings are made: H2 / (H1+H2+H3)≥20% and H3 / (H1+H2+H3)≥20%.

[0207] According to some embodiments of this application, refer to Figure 6 and Figure 7 This application also provides a separating membrane, comprising: a first membrane 2121 and a second membrane 2122 and a third membrane 2123 located on both sides of the first membrane 2121 along the thickness direction, wherein the porosity of the first membrane 2121 is P1, the porosity of the second membrane 2122 is P2, and the porosity of the third membrane 2123 is P3, satisfying: P1 > P2, P1 > P3.

[0208] According to the separator provided in the embodiments of this application, by setting the base membrane of the separator to a three-layer structure with a porosity gradient, the first membrane 2121 (middle layer) is a high-porosity membrane, and the second membrane 2122 and the third membrane 2123 (side layers) are low-porosity membranes. The high-porosity membrane can increase the electrolyte storage capacity, and the low-porosity membrane can increase the difficulty of electrolyte flowing out of the separator when the battery cell 20 is impacted. Thus, the separator can provide a better liquid buffering effect when the battery cell 20 is impacted. Compared with conventional separator design, it can improve the impact resistance of the battery cell 20 and improve the reliability of the battery cell 20, thereby helping to reduce the risk of short circuit when the battery cell 20 is impacted by external force.

[0209] The processing methods for the base film of the separator include at least the following four methods:

[0210] Firstly, the impregnation and roll pressing composite method: by impregnating material layers with different pore sizes in a binder and metal halide solution, and then rolling them layer by layer to form a gradient pore structure;

[0211] Secondly, the casting and lamination pressing method: by adjusting the material ratio, membranes with different pore sizes are prepared, and then laminated and pressed to form a gradient;

[0212] Third, the pore-forming agent gradient method: using pore-forming agents of different molecular weights to form a gradient pore structure;

[0213] Fourth, template agent control method: using template agents to precisely control the porosity of each layer to form a gradient structure.

[0214] According to some embodiments of this application, this application also provides a battery device, which includes a plurality of battery cells 20.

[0215] According to some embodiments of this application, this application also provides an energy storage device 1, which includes a plurality of battery cells 20 of any kind, the battery cells 20 being used to store or provide electrical energy; or the energy storage device 1 includes a plurality of battery devices of any kind, the battery devices being used to store or provide electrical energy.

[0216] According to some embodiments of this application, this application also provides an energy storage system, which includes: a power conversion device 2 and an energy storage device 1 of any of the above schemes, wherein the power conversion device 2 is used to electrically connect the power generation equipment 3 and the energy storage device 1.

[0217] According to some embodiments of this application, this application also provides an electrical device. The electrical device includes a battery cell 20 of any of the above-described embodiments, the battery cell 20 being used to store or provide electrical energy; or the electrical device includes a battery device of any of the above-described embodiments, the battery device being used to store or provide electrical energy; or the electrical device includes an energy storage device 1 of any of the above-described embodiments, the battery cell 20 or the battery device being used to store or provide electrical energy; or the electrical device includes an energy storage system of any of the above-described embodiments, the battery cell 20 or the battery device being used to store or provide electrical energy.

[0218] The electrical device can be any of the aforementioned devices or systems that utilize battery devices.

[0219] According to some embodiments of this application, this application also provides a charging network, which includes a charging pile 4 and an energy storage device 1 or an energy storage system of any of the above schemes, wherein the energy storage device 1 is used to provide electrical energy to the charging pile 4.

[0220] The energy storage device 1 can be located inside the charging pile 4 (e.g., an integrated energy storage and charging unit) or outside the charging pile 4.

[0221] According to some embodiments of this application, see Figures 5-7As shown, this application provides a battery cell 20, which includes a housing and an electrode assembly 21, wherein the electrode assembly 21 is disposed within the housing. Figure 6 The electrode assembly 21 includes a first electrode 211, a separator, and a second electrode 213, with the separator disposed between the first electrode 211 and the second electrode 213.

[0222] Reference Figure 7 At least the layer of the isolation membrane closest to the outer shell is a first type of isolation membrane 212. The first type of isolation membrane 212 includes a first membrane body 2121 and a second membrane body 2122 and a third membrane body 2123 located on both sides of the first membrane body 2121 along the thickness direction. The porosity of the first membrane body 2121 is P1, the porosity of the second membrane body 2122 is P2, and the porosity of the third membrane body 2123 is P3, satisfying: P1 > P2, P1 > P3.

[0223] The first type of separator membrane includes five layers along the thickness direction: coating 2124, second membrane 2122, first membrane 2121, third membrane 2123, and coating 2124. The second membrane 2122, first membrane 2121, and third membrane 2123 are combined to form the base membrane structure of the separator membrane. The first membrane 2121 is a high-porosity membrane, while the second membrane 2122 and third membrane 2123 are low-porosity membranes.

[0224] According to the battery cell 20 provided in the embodiments of this application, by setting the base membrane of the first type of separator 212 as a three-layer structure with a porosity gradient, the first membrane 2121 (middle layer) is a high-porosity membrane, and the second membrane 2122 and the third membrane 2123 (side layers) are low-porosity membranes. The high-porosity membrane can increase the electrolyte storage capacity, and the low-porosity membrane can increase the difficulty of electrolyte flowing out of the separator when the battery cell 20 is impacted. Thus, the first type of separator 212 can provide a better liquid buffering effect when the battery cell 20 is impacted. Compared with conventional separator design, it can improve the impact resistance of the battery cell 20 and improve the reliability of the battery cell 20, thereby helping to reduce the risk of short circuit when the battery cell 20 is impacted by external force.

[0225] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0226] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0227] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized in that, include: shell; An electrode assembly is disposed within the housing. The electrode assembly includes a first electrode, a separating membrane, and a second electrode, wherein the separating membrane is disposed between the first electrode and the second electrode. At least the layer of the isolation membrane closest to the outer shell is a first type of isolation membrane. The first type of isolation membrane includes a first membrane body and a second membrane body and a third membrane body located on both sides of the first membrane body along the thickness direction. The porosity of the first membrane body is P1, the porosity of the second membrane body is P2, and the porosity of the third membrane body is P3, satisfying: P1 > P2, P1 > P3.

2. The battery cell according to claim 1, characterized in that, The electrode assembly is of the wound type, and the porosity of the first type of separator monotonically does not increase from the outside to the inside along the winding direction.

3. The battery cell according to claim 2, characterized in that, The electrode assembly is a wound type. Along the winding direction of the electrode assembly, the porosity of the first membrane in the outermost region of the first type of separator is greater than the porosity of other regions of the first type of separator.

4. The battery cell according to claim 1, characterized in that, The electrode assembly further includes a second type of isolation membrane. Along the winding direction of the electrode assembly, the innermost end of the first type of isolation membrane is connected to the outermost end of the second type of isolation membrane, and the average porosity of the second type of isolation membrane is less than that of the first type of isolation membrane.

5. The battery cell according to any one of claims 1-4, characterized in that, The electrode assembly is of the wound type, wherein the side of the first membrane facing the second membrane along the width direction is connected to the side of the second membrane along the width direction, and the side of the first membrane facing the third membrane along the width direction is connected to the side of the third membrane along the width direction.

6. The battery cell according to any one of claims 1-4, characterized in that, The second membrane and the third membrane protrude from the end of the first membrane along the width direction, and the side of the second membrane distributed along the width direction is connected to the side of the third membrane distributed along the width direction.

7. The battery cell according to claim 1, characterized in that, The electrode assembly is a stacked type, and multiple isolation membranes are distributed at intervals along the stacking direction. In the stacking direction, the porosity of the first membrane located on the outermost layer is greater than that of the first membrane located on the middle layer.

8. The battery cell according to claim 7, characterized in that, The porosity of the plurality of first membranes decreases monotonically from the outermost layer to the middle layer along the stacking direction.

9. The battery cell according to claim 7 or 8, characterized in that, The electrode assembly is a stacked type, with the periphery of the side of the first membrane facing the second membrane connected to the periphery of the second membrane, and the periphery of the side of the first membrane facing the third membrane connected to the periphery of the third membrane.

10. The battery cell according to claim 7 or 8, characterized in that, The second membrane protrudes from the end of the first membrane in a direction perpendicular to the thickness direction, and the third membrane protrudes from the end of the first membrane in a direction perpendicular to the thickness direction. The periphery of the second membrane and the periphery of the third membrane are connected.

11. The battery cell according to any one of claims 1-10, characterized in that, The following conditions must be met: P1-P2 > 10%, P1-P3 > 10%.

12. The battery cell according to any one of claims 1-11, characterized in that, The following conditions must be met: 40% ≤ P1 ≤ 60%, 30% ≤ P2 ≤ 40%, and 30% ≤ P3 ≤ 40%.

13. The battery cell according to any one of claims 1-12, characterized in that, The second membrane and the third membrane have different thicknesses.

14. The battery cell according to any one of claims 1-13, characterized in that, The thickness of the first membrane is H1, the thickness of the second membrane is H2, and the thickness of the third membrane is H3, satisfying the following condition: 20% ≤ H1 / (H1+H2+H3) ≤ 40%.

15. The battery cell according to any one of claims 1-13, characterized in that, The thickness of the first membrane is H1, the thickness of the second membrane is H2, and the thickness of the third membrane is H3, satisfying: H2 / (H1+H2+H3)≥20%, H3 / (H1+H2+H3)≥20%.

16. A separating membrane, characterized in that, include: A first membrane and a second and a third membrane located on either side of the first membrane along the thickness direction, wherein the porosity of the first membrane is P1, the porosity of the second membrane is P2, and the porosity of the third membrane is P3, satisfying: P1 > P2, P1 > P3.

17. A battery device, characterized in that, include: The battery cell as described in any one of claims 1-15.

18. An electrical appliance, characterized in that, include: The battery cell as described in any one of claims 1-15, or the battery device as described in claim 17, wherein the battery cell or the battery device is used to store or provide electrical energy.

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