Isolation film, battery, and electric device

Abstract

The application discloses an isolation film, a battery and a power utilization device. The isolation film comprises a porous substrate and a coating arranged on at least one surface of the porous substrate, wherein the coating comprises a fibrous material and a particulate filler, the fibrous material comprises a first fibrous material and a second fibrous material, the average length of the first fibrous material is denoted as L1, the average length of the second fibrous material is denoted as L2, L1 is greater than 800 nm, and L1 / L2 is greater than or equal to 2.4. The application can make the battery have high reliability and good cycle performance.

Description

Technical Field

[0001] This application relates to a separator, a battery, and an electrical device. Background Technology

[0002] In recent years, batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and many other fields. With the application and promotion of batteries, their reliability, especially thermal stability, has received increasing attention. However, current methods for improving battery thermal stability often do not balance battery energy density and lifespan; furthermore, a sustained increase in battery temperature can easily lead to internal short circuits and induce thermal runaway, even causing safety accidents such as fires and explosions. The above statements are only for providing background information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0003] This application provides a separator, a battery, and an electrical device that enable the battery to have high reliability and good cycle performance.

[0004] In a first aspect, this application provides a separating membrane, comprising a porous substrate and a coating disposed on at least one surface of the porous substrate, the coating comprising a fibrous material and particulate filler, the fibrous material comprising a first fibrous material and a second fibrous material, the average length of the first fibrous material being denoted as L1, the average length of the second fibrous material being denoted as L2, L1 being greater than 800 nm, and L1 / L2 ≥ 2.4.

[0005] By including both a first fiber material and a second fiber material in the fiber material, and ensuring that the average length L1 of the first fiber material and the average length L2 of the second fiber material satisfy L1 > 800 nm and L1 / L2 ≥ 2.4, the second fiber material, having a smaller average length, can be flexibly interwoven between the first fiber materials to act as a connector. This allows for an integrated coating with a dendritic structure, thereby reducing the content of free filler particles in the coating, minimizing pore blockage, and improving the heat resistance of the separator.

[0006] In addition, by making the fiber material simultaneously include a first fiber material and a second fiber material, and by ensuring that the average length L1 of the first fiber material and the average length L2 of the second fiber material satisfy L1 > 800 nm and L1 / L2 ≥ 2.4, during electrolyte injection, the electrolyte can also quickly wet the separator along the first and second fiber materials. As a result, the separator can still have good electrolyte wettability and liquid retention during rapid charging and discharging of the battery, which is beneficial for ion transport and dendrite reduction, thereby enabling the battery to have good cycle performance.

[0007] Therefore, by simultaneously including a first fiber material and a second fiber material in the fiber material, and ensuring that the average length L1 of the first fiber material and the average length L2 of the second fiber material satisfy L1 > 800 nm and L1 / L2 ≥ 2.4, the coating can have a dendritic structure. Furthermore, the first fiber material, the second fiber material, and the filler particles can overlap to form an integrated coating. Thus, the separator provided in this application embodiment can possess good heat resistance, good air permeability, and good electrolyte wettability and liquid retention, thereby helping to reduce the risk of battery failure during use and enabling the battery to have high reliability and good cycle performance.

[0008] In some embodiments, L1 / L2 is 2.4-9.0, and optionally 2.7-5.8.

[0009] By further adjusting L1 / L2 within the aforementioned range, the first and second fiber materials can be better overlapped, which is beneficial for further increasing the heat resistance of the separator, reducing the content of free filler particles in the coating, and also facilitates the rapid wetting of the separator by the electrolyte along the first and second fiber materials, improving the electrolyte wettability and liquid retention of the separator, thereby enabling the battery to have higher reliability and better cycle performance.

[0010] In some embodiments, the average length L1 of the first fiber material is 850nm-3000nm, and can be selected as 1000nm-2000nm.

[0011] In some embodiments, the average length L2 of the second fiber material is 200nm-800nm, and can be selected as 300nm-550nm.

[0012] By further adjusting the average length of the first fiber material and / or the second fiber material within the above-mentioned range, it is beneficial to further reduce the risk of battery failure during use and to further improve the cycle performance of the battery.

[0013] In some embodiments, the average diameter of the first fiber material is greater than the average diameter of the second fiber material.

[0014] By further increasing the average diameter of the first fiber material to be larger than that of the second fiber material, it is beneficial for the first and second fiber materials to overlap and form a dendritic structure. It is also beneficial for the first and second fiber materials to overlap with the filler particles to form an integrated coating, reducing the content of free filler particles. This is beneficial for further improving the heat resistance of the separator, reducing the problem of separator pore blockage, improving the electrolyte wettability and electrolyte retention of the separator, and further reducing the risk of battery failure during use. It is also beneficial for further improving the cycle performance of the battery.

[0015] In some embodiments, the average diameter of the first fiber material is less than or equal to 100 nm, and may be 25 nm to 75 nm.

[0016] In some embodiments, the average diameter of the second fiber material is 12nm-40nm, and optionally 15nm-32nm.

[0017] By adjusting the average diameter of the first fiber material and / or the second fiber material within the aforementioned range, it is beneficial for the first and second fiber materials to overlap and form a dendritic structure. It is also beneficial for the first and second fiber materials to overlap with the filler particles to form an integrated coating, reducing the content of free filler particles. This is beneficial for improving the heat resistance of the separator, reducing the problem of separator pore blockage, improving the electrolyte wettability and electrolyte retention of the separator, and further reducing the risk of battery failure during use. It is also beneficial for further improving the cycle performance of the battery.

[0018] In some embodiments, the aspect ratio of the first fiber material is greater than that of the second fiber material.

[0019] By further increasing the aspect ratio of the first fiber material to be greater than that of the second fiber material, it is beneficial for the first fiber material to connect more filler particles, and for the second fiber material to better connect between the first fibers, allowing the first and second fibers to overlap and form a dendritic structure. It also facilitates the overlap of the first and second fibers with the filler particles to form an integrated coating, reducing the content of free filler particles. This improves the heat resistance of the separator, reduces pore clogging, and enhances the electrolyte wettability and electrolyte retention of the separator. Therefore, by further increasing the aspect ratio of the first fiber material to be greater than that of the second fiber material, the risk of battery failure during use can be further reduced, and the cycle performance of the battery can be further improved.

[0020] In some embodiments, the aspect ratio of the first fiber material is 12-100, and optionally 20-50.

[0021] In some embodiments, the aspect ratio of the second fiber material is 10-70, optionally 15-40.

[0022] By adjusting the aspect ratio of the first fiber material and / or the second fiber material within the above-mentioned range, it is beneficial for the first fiber material and the second fiber material to overlap and form a dendritic structure. It is also beneficial for the first fiber material, the second fiber material and the filler particles to overlap and form an integrated coating, reducing the content of free filler particles. This is beneficial for improving the heat resistance of the separator, reducing the problem of separator pore blockage, improving the electrolyte wettability and electrolyte retention of the separator, and further reducing the risk of battery failure during use. It is also beneficial for further improving the cycle performance of the battery.

[0023] In some embodiments, the content of the first fiber material is less than the content of the second fiber material.

[0024] By adjusting the content of the first fiber material to be less than that of the second fiber material, more of the second fiber material can be better connected between the first fiber materials. This facilitates the formation of a dendritic structure with more branches, which in turn allows the electrolyte to quickly wet the separator along the first and second fiber materials, improving the electrolyte wettability and liquid retention of the separator, and further improving the cycle performance of the battery.

[0025] In some embodiments, the content of the first fiber material is denoted as W. 11 The content of the second fiber material is denoted as W. 12 All are based on the total mass of the coating, W 11 / W 12 The value is 0.20-0.95, and can be selected as 0.40-0.75.

[0026] By further adjusting W 11 / W 12 Within the aforementioned range, the performance of the separator and the battery can be further improved.

[0027] In some embodiments, the content of the first fiber material is denoted as W. 11 Based on the total mass of the coating, W 11 It ranges from 5 wt% to 13 wt%.

[0028] In some embodiments, the content of the second fiber material is denoted as W. 12 Based on the total mass of the coating, W 12 It ranges from 9wt% to 21wt%.

[0029] By adjusting the content of the first fiber material and / or the second fiber material within the above range, the first fiber material and the second fiber material can be better overlapped, which is beneficial to increasing the heat resistance of the separator, reducing the content of free filler particles in the coating, and also beneficial to the electrolyte quickly wetting the separator along the first fiber material and the second fiber material, thereby improving the electrolyte wettability and liquid retention of the separator.

[0030] In some embodiments, the first fiber material and the second fiber material each independently comprise at least one of organic fiber material and inorganic fiber material.

[0031] Optionally, the organic fiber material includes at least one of nanocellulose, polytetrafluoroethylene nanofibers, and polyamide nanofibers.

[0032] Optionally, the inorganic fiber material includes at least one of halloysite nanotubes, nanorod alumina, nanorod boehmite, nanorod silica, and glass fiber.

[0033] In some embodiments, the first fiber material and the second fiber material each independently comprise nanocellulose.

[0034] Optionally, the nanocellulose includes a modifying group, which includes at least one of an amino group, a carboxyl group, an aldehyde group, a sulfonic acid group, and a phosphate group, and more preferably includes at least one of a sulfonic acid group and a phosphate group.

[0035] Optionally, the nanocellulose includes hydroxyl groups and modified groups, and the molar ratio of the modified groups to the hydroxyl groups is 1:4 to 4:1, more preferably 2:3 to 7:3.

[0036] In some embodiments, the particulate packing includes a first packing and a second packing, wherein the average particle size D1 of the first packing is smaller than the average particle size D2 of the second packing.

[0037] By including both a first filler and a second filler in the granular filler, and making the average particle size D1 of the first filler smaller than the average particle size D2 of the second filler, a certain space can be formed around the particles of the second filler in the coating. This can improve the air permeability of the separator and also help retain the electrolyte after impregnation, thereby improving the electrolyte retention and ion transport characteristics of the separator. Furthermore, the first filler particles can fill the gaps between the particles of the second filler, thereby reducing the thermal shrinkage of the separator and improving its heat resistance.

[0038] In some embodiments, the average particle size D1 of the first filler and the average particle size D2 of the second filler satisfy D2 / D1≥1.2; optionally, D2 / D1 is 1.5-16, and more preferably 2-8.

[0039] By further adjusting D2 / D1 within the aforementioned range, the performance of the separator can be improved, giving it good air permeability, good electrolyte wettability and liquid retention, as well as good heat resistance. It can also allow the first and second fillers to better overlap with the first and second fiber materials to form an integrated coating, reducing the content of free filler particles. This can further reduce the risk of battery failure during use and further improve the battery's cycle performance.

[0040] In some embodiments, the first filler has a secondary particle morphology, and the second filler has a primary particle morphology.

[0041] The secondary particles are formed by the aggregation of multiple primary particles, and the primary filler with the secondary particle morphology can better overlap with the primary and secondary fiber materials to form an integrated coating. This helps to give the coating a stable spatial network structure, which helps to improve the heat resistance of the separator. The secondary filler with the primary particle morphology helps to reduce the moisture content of the coating, improve the air permeability and ion conductivity of the coating, thereby helping to improve the cycle performance of the battery.

[0042] In some embodiments, the ratio L1 / D2 of the average length L1 of the first fiber material to the average particle size D2 of the second filler is 3.0-5.0.

[0043] By keeping L1 / D2 within the aforementioned range, more second filler particles can be connected to the first fiber material in the coating, which is beneficial for forming an integrated coating and thus for improving the heat resistance, electrolyte wettability, and liquid retention of the separator.

[0044] In some embodiments, the ratio L2 / D1 of the average length L2 of the second fiber material to the average particle size D1 of the first filler is 2.0-4.0.

[0045] By keeping L2 / D1 within the aforementioned range, more second filler particles can be connected to the second fiber material in the coating, which is beneficial for forming an integrated coating and thus for improving the heat resistance, electrolyte wettability, and liquid retention of the separator.

[0046] In some embodiments, the average particle size D1 of the first filler is less than 200 nm, and can be selected as 50 nm-185 nm.

[0047] The average particle size of the first filler is within the above range, making it easier to overlap with the first and second fiber materials to form an integrated coating, thereby improving the heat resistance, electrolyte wettability and liquid retention of the separator.

[0048] In some embodiments, the average particle size D2 of the second filler is 200nm-800nm, and can be selected as 210nm-400nm.

[0049] The average particle size of the second filler is within the above range, which helps the coating maintain a stable pore structure during long-term charge and discharge, reduces the moisture content of the coating, improves the air permeability and ion conductivity of the coating, and thus helps improve the cycle performance of the battery.

[0050] In some embodiments, the average particle size of the primary particles constituting the first filler is 10nm-50nm, and optionally 15nm-35nm.

[0051] If the average particle size of the primary particles constituting the first filler is within the above-mentioned range, the first filler can have a good secondary particle morphology, which is beneficial to improving the bonding effect between the first filler and the first fiber material and the second fiber material.

[0052] In some embodiments, the specific surface area of ​​the first packing is greater than that of the second packing.

[0053] The first filler has a larger specific surface area and better affinity with the first and second fiber materials, which can make the coating have a more stable spatial network structure, and give the separator membrane better heat resistance and higher ion conductivity; the second filler has a smaller specific surface area, which is beneficial to reducing the moisture content of the separator membrane.

[0054] In some embodiments, the specific surface area of ​​the first packing is greater than or equal to 20 m². 2 / g, optional 30m 2 / g-80m 2 / g.

[0055] When the specific surface area of ​​the first filler is within the above-mentioned range, it is beneficial to further improve the heat resistance and ion conductivity of the separator. In addition, it is also beneficial to improve the affinity between the first filler and the first fiber material and the second fiber material, so that the coating can have a more stable spatial network structure, and thus the separator has better heat resistance and higher ion conductivity.

[0056] In some embodiments, the specific surface area of ​​the second packing is less than 20 m². 2 / g, optional 5m 2 / g-15m 2 / g.

[0057] The specific surface area of ​​the second filler is within the above range, which helps to reduce the moisture content of the separator, thereby reducing the battery capacity decay rate and improving the battery cycle performance.

[0058] In some embodiments, the content of the first filler is greater than the content of the second filler.

[0059] This helps to better utilize the functions of the first and second fillers, improves the heat resistance of the separator, and enhances the electrolyte retention of the separator.

[0060] In some embodiments, the content of the first filler is denoted as W. 21 The content of the second filler is denoted as W. 22 All are based on the total mass of the coating, W 22 / W 21 The range is 0.10-0.80, and can be set to 0.25-0.50.

[0061] In some embodiments, the content of the first filler is denoted as W. 21 Based on the total mass of the coating, W 21 The range is 20wt%-70wt%, with an optional range of 36wt%-61.5wt%.

[0062] The content of the first filler within the above range is beneficial for the coating slurry to have a suitable viscosity, which is more conducive to coating; in addition, it is also beneficial for the coating to have a more stable spatial network structure, thereby enabling the separator to have better heat resistance and higher ion conductivity.

[0063] In some embodiments, the content of the second filler is denoted as W. 22 Based on the total mass of the coating, W 22 Available in 5wt%-60wt%, with an optional range of 10wt%-35wt%.

[0064] The content of the second filler is within the above range, which is beneficial for the coating to maintain a stable pore structure during long-term charge and discharge, thereby reducing the moisture content of the separator and preserving the electrolyte after impregnation, thus improving the cycle performance of the battery.

[0065] In some embodiments, the first filler comprises at least one of inorganic particles and organic particles.

[0066] Optionally, the inorganic particles include at least one of boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon oxide, tin dioxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, hafnium dioxide, cerium oxide, zirconium titanate, barium titanate, and magnesium fluoride. More preferably, the inorganic particles include at least one of boehmite, alumina, barium sulfate, magnesium oxide, silicon oxide, titanium oxide, zinc oxide, cerium oxide, and barium titanate.

[0067] Optionally, the organic particles include at least one of polystyrene and polyacrylic wax.

[0068] In some embodiments, the second filler comprises at least one of inorganic particles having a dielectric constant of 5 or higher, inorganic particles having ion conductivity but not storing ions, and inorganic particles capable of undergoing electrochemical reactions.

[0069] In some embodiments, the first filler comprises inorganic particles with secondary particle morphology, and the crystal form of the inorganic particles with secondary particle morphology includes at least two of the following: α-crystal form, θ-crystal form, γ-crystal form, and η-crystal form. Optionally, the crystal form of the inorganic particles with secondary particle morphology includes at least two of the following: α-crystal form, θ-crystal form, and γ-crystal form.

[0070] Optionally, the content of the α-crystalline secondary particle morphology inorganic particles in the secondary particle morphology inorganic particles is greater than or equal to 1.2 wt%, and more preferably from 1.2 wt% to 10 wt%, based on the total mass of the secondary particle morphology inorganic particles.

[0071] Optionally, the content of the inorganic particles with the θ-type secondary particle morphology in the inorganic particles with the secondary particle morphology is greater than or equal to 50 wt%, and more preferably 60 wt% to 85 wt%, based on the total mass of the inorganic particles with the secondary particle morphology.

[0072] Optionally, the content of the γ-crystalline secondary particle morphology inorganic particles in the secondary particle morphology inorganic particles is greater than or equal to 10 wt%, and more preferably 15 wt% to 60 wt%, based on the total mass of the secondary particle morphology inorganic particles.

[0073] Optionally, the content of the inorganic particles with the secondary particle morphology of the η-crystal type in the inorganic particles with the secondary particle morphology is less than or equal to 5 wt%, and more preferably less than or equal to 2 wt%, based on the total mass of the inorganic particles with the secondary particle morphology.

[0074] In some embodiments, the second filler comprises inorganic particles with a primary particle morphology, wherein the crystal form of the inorganic particles with the primary particle morphology includes at least one of α-crystal form and γ-crystal form, and optionally includes α-crystal form.

[0075] Optionally, the content of inorganic particles with primary α-crystalline morphology in the second filler is greater than or equal to 90 wt%, and more preferably 95 wt% to 100 wt%, based on the total mass of the second filler.

[0076] In some embodiments, the coating further includes a non-particulate binder.

[0077] Optionally, the non-particulate adhesive includes an aqueous solution-based adhesive.

[0078] Optionally, the content of the non-particulate binder in the coating is less than or equal to 2 wt%, based on the total mass of the coating.

[0079] In some embodiments, the isolation membrane further includes an adhesive layer disposed on at least a portion of the surface of the coating.

[0080] Optionally, the adhesive layer comprises a particulate adhesive. More preferably, the particulate adhesive comprises at least one of acrylate monomer homopolymers or copolymers, acrylate monomer homopolymers or copolymers, and fluorinated olefin monomer homopolymers or copolymers.

[0081] In some embodiments, the thickness of the porous substrate is less than or equal to 5 μm, and can be selected as 3 μm-4.5 μm.

[0082] In some embodiments, the thickness of the coating is less than or equal to 3 μm, and can be selected as 0.3 μm-2 μm.

[0083] In some embodiments, the heat shrinkage rate of the separator at 150°C for 1 hour is less than 2% in both the transverse and longitudinal directions.

[0084] In some embodiments, the air permeability of the isolation membrane is less than or equal to 300s / 100mL, and can be selected as 100s / 100mL-240s / 100mL.

[0085] In some embodiments, the wetting rate of the separator is greater than or equal to 3 mm / s, and can be selected as 5 mm / s-15 mm / s.

[0086] Secondly, this application provides a battery including the separator membrane of the first aspect of this application.

[0087] Thirdly, this application provides an electrical device that includes the battery described in the second aspect of this application.

[0088] The electrical device of this application includes the battery provided in this application, and therefore has at least the same advantages as the battery. Attached Figure Description

[0089] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0090] Figure 1 The diagram shows a schematic of a battery cell provided in some embodiments of this application.

[0091] Figure 2An exploded view of a battery cell provided in some embodiments of this application is shown.

[0092] Figure 3 This document shows schematic diagrams of battery modules provided in some embodiments of this application.

[0093] Figure 4 This illustration shows a schematic diagram of a battery pack provided in some embodiments of this application.

[0094] Figure 5 yes Figure 4 The diagram shown is an exploded view of the battery pack.

[0095] Figure 6 A schematic diagram of an electrical device provided in some embodiments of this application is shown.

[0096] The accompanying drawings are not necessarily drawn to scale. The reference numerals are explained as follows: 1 Battery pack, 2 Upper casing, 3 Lower casing, 4 Battery module, 5 Individual battery cell, 51 Housing, 52 Electrode assembly, 53 Cover plate. Detailed Implementation

[0097] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the separator, battery, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0098] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0099] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0100] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0101] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0102] Unless otherwise specified, in this application, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0103] In this application, the terms "multiple" or "various" refer to two or more kinds.

[0104] In the description of the embodiments of this application, unless otherwise specified, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0105] Unless otherwise stated, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0106] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in the embodiments of this application. Unless otherwise stated, the test temperature for each parameter is 25°C.

[0107] The battery mentioned in the embodiments of this application can be a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application can include battery cells, battery modules, or battery packs.

[0108] A battery cell is the smallest unit that makes up a battery, and it can independently perform the functions of charging and discharging. A battery cell can be cylindrical, cuboid, or other shapes, etc., and the embodiments of this application are not limited in this respect. Figure 1 The example shown is a rectangular battery cell 5.

[0109] When there are multiple battery cells, they are connected in series, parallel, or mixed via a busbar. In some embodiments, the battery can be a battery module; when there are multiple battery cells, they are arranged and fixed to form a battery module. In some embodiments, the battery can be a battery pack, which includes a housing and battery cells, with the battery cells or battery modules housed within the housing. In some embodiments, the housing can be part of the vehicle's chassis structure. For example, a portion of the housing can be at least part of the vehicle's floor, or a portion of the housing can be at least part of the vehicle's crossbeams and longitudinal beams.

[0110] In some embodiments, the battery can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0111] A single battery cell generally includes an electrode assembly and an electrolyte. The electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited in this regard.

[0112] The battery cell may also include an outer packaging, which can be used to encapsulate the electrode components and electrolyte. The outer packaging can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. The outer packaging can also be a flexible package, such as a pouch-type flexible package. The material of the flexible package can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0113] In some embodiments, such as Figure 2 As shown, the outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates enclosing a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 is used to cover the opening to close the receiving cavity. Electrode assemblies 52 are encapsulated in the receiving cavity. The number of electrode assemblies 52 contained in the battery cell 5 may be one or more, and can be adjusted according to requirements.

[0114] In some embodiments, individual battery cells can be assembled into a battery module, and the number of individual battery cells contained in the battery module can be multiple, the specific number of which can be adjusted according to the application and capacity of the battery module. Figure 3 This is a schematic diagram of battery module 4 as an example. Figure 3 As shown, in battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0115] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0116] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0117] Figure 4 and Figure 5 This is a schematic diagram of battery pack 1 as an example. Figure 4 and Figure 5 As shown, the battery pack 1 may include a housing and multiple battery modules 4 disposed within the housing. The housing includes an upper housing 2 and a lower housing 3. The upper housing 2 covers the lower housing 3, forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the housing.

[0118] The batteries provided in the embodiments of this application may include, but are not limited to, lithium batteries and sodium batteries, such as lithium-ion batteries and sodium-ion batteries.

[0119] Typically, an electrode assembly includes a positive electrode, a negative electrode, and a separator. The separator is placed between the positive and negative electrodes, and its main function is to prevent short circuits between the positive and negative electrodes, while allowing ions to pass freely to form a circuit.

[0120] Currently, commercially available batteries typically use polyolefin porous membranes as separators, which have poor heat resistance. When heated, they exhibit significant thermal shrinkage, causing direct contact between the positive and negative electrodes inside the battery, leading to internal short circuits. This can easily induce thermal runaway, and in severe cases, the battery may even catch fire or explode.

[0121] To address these issues, current methods primarily involve coating a heat-resistant inorganic ceramic layer onto a polyolefin porous membrane. This increases the mechanical strength of the separator, reduces its shrinkage under heat, and lowers the risk of short circuits between the positive and negative electrodes within the battery. However, commercially available inorganic ceramic particles have relatively large particle sizes, which increases the overall thickness of the separator and makes it difficult to balance the battery's energy density. This is particularly problematic in the power battery sector, hindering improvements in driving range.

[0122] This application provides an isolation membrane.

[0123] The separator includes a porous substrate and a coating disposed on at least one surface of the porous substrate. The coating includes a fibrous material and particulate fillers. The fibrous material includes a first fibrous material and a second fibrous material. The average length of the first fibrous material is denoted as L1, and the average length of the second fibrous material is denoted as L2. L1 is greater than 800 nm, and L1 / L2 ≥ 2.4.

[0124] The term "fiber material" refers to materials with an aspect ratio of 5 or greater.

[0125] The first and second fiber materials have a linear structure. The average length L1 of the first fiber material is greater than 800 nm, which allows for the connection of more filler particles. However, the overlap between the first fibers is usually poor, and the first fiber material is more likely to come into contact with larger filler particles. This may leave some smaller filler particles in a free state, leading to pore blockage and reducing the heat resistance of the separator. By including both the first and second fiber materials in the fiber material, and ensuring that the average length L1 of the first fiber material and the average length L2 of the second fiber material satisfy L1 > 800 nm and L1 / L2 ≥ 2.4, the second fiber material, with its smaller average length, can flexibly interweave between the first fibers to act as a connector. This allows for a unified coating with a dendritic structure, reducing the content of free filler particles in the coating, minimizing pore blockage, and improving the heat resistance of the separator. Furthermore, compared to inorganic ceramic coatings, the separator coating provided in this embodiment can achieve both low thickness and high heat resistance.

[0126] In addition, by making the fiber material simultaneously include a first fiber material and a second fiber material, and by ensuring that the average length L1 of the first fiber material and the average length L2 of the second fiber material satisfy L1 > 800 nm and L1 / L2 ≥ 2.4, during electrolyte injection, the electrolyte can also quickly wet the separator along the first and second fiber materials. As a result, the separator can still have good electrolyte wettability and liquid retention during rapid charging and discharging of the battery, which is beneficial for ion transport and dendrite reduction, thereby enabling the battery to have good cycle performance.

[0127] Therefore, by simultaneously including a first fiber material and a second fiber material in the fiber material, and ensuring that the average length L1 of the first fiber material and the average length L2 of the second fiber material satisfy L1 > 800 nm and L1 / L2 ≥ 2.4, the coating can have a dendritic structure. Furthermore, the first fiber material, the second fiber material, and the filler particles can overlap to form an integrated coating. Thus, the separator provided in this application embodiment can possess good heat resistance, good air permeability, and good electrolyte wettability and liquid retention, thereby helping to reduce the risk of battery failure during use and enabling the battery to have high reliability and good cycle performance.

[0128] In addition, the separator provided in this application embodiment has good heat resistance, which allows the separator to maintain high heat resistance while being relatively thin, thus also contributing to the high energy density of the battery. At the same time, the separator provided in this application embodiment can also reduce the probability of short circuit due to misalignment of the positive and negative electrode edges during battery manufacturing, thereby reducing the failure risk during battery use and the failure risk during battery manufacturing, and improving the process yield of battery products.

[0129] In some embodiments, the average length L1 of the first fiber material and the average length L2 of the second fiber material can satisfy L1 / L2 being 2.4-9.0, for example, it can be 2.4, 2.7, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, 5.2, 5.4, 5.6, 5.8, 6.0, 6.3, 6.6, 6.9, 7.2, 7.5, 7.8, 8.2, 8.6, 9.0, or any range of the above values.

[0130] Optionally, L1 / L2 can be 2.7-5.8 or 3.0-5.0.

[0131] By further adjusting L1 / L2 within the aforementioned range, the first and second fiber materials can be better overlapped, which is beneficial for further increasing the heat resistance of the separator, reducing the content of free filler particles in the coating, and also facilitates the rapid wetting of the separator by the electrolyte along the first and second fiber materials, improving the electrolyte wettability and liquid retention of the separator, thereby enabling the battery to have higher reliability and better cycle performance.

[0132] In some embodiments, the average length L1 of the first fiber material can be 850nm-3000nm, and optionally 1000nm-2000nm.

[0133] By adjusting the average length of the first fiber material within the aforementioned range, more filler particles can be connected to the same mass of the first fiber material.

[0134] In some embodiments, the average length L2 of the second fiber material can be 200nm-800nm, and optionally 300nm-550nm.

[0135] By adjusting the average length of the second fiber material to the above range, it is beneficial for the second fiber material to better connect with the first fiber material.

[0136] By adjusting the average length of the first and / or second fiber materials within the aforementioned range, it is beneficial for the first and second fiber materials to overlap and form a dendritic structure. It also facilitates the overlap of the first and second fiber materials with filler particles to form an integrated coating, reducing the content of free filler particles. This improves the heat resistance of the separator and reduces pore blockage. Adjusting the average length of the first and / or second fiber materials within the aforementioned range also facilitates rapid wetting of the separator by the electrolyte along the first and second fiber materials, enhancing the electrolyte wettability and liquid retention of the separator, thus promoting ion transport and reducing dendrite formation. Furthermore, adjusting the average length of the first and / or second fiber materials within the aforementioned range ensures the coating slurry has a suitable viscosity, which is beneficial for coating application and improves the uniformity and consistency of the coating.

[0137] Therefore, by further adjusting the average length of the first fiber material and / or the second fiber material within the above-mentioned range, it is beneficial to further reduce the risk of battery failure during use and to further improve the cycle performance of the battery.

[0138] In some embodiments, the average diameter of the first fiber material may be greater than the average diameter of the second fiber material.

[0139] When the average length of the second fiber material is small and the average diameter is large, the connecting effect of the second fiber material between the first fiber materials will be poor under the same mass, which is not conducive to the formation of a dendritic structure by overlapping with the first fiber material.

[0140] By further increasing the average diameter of the first fiber material to be larger than that of the second fiber material, it is beneficial for the first and second fiber materials to overlap and form a dendritic structure. It is also beneficial for the first and second fiber materials to overlap with the filler particles to form an integrated coating, reducing the content of free filler particles. This is beneficial for further improving the heat resistance of the separator, reducing the problem of separator pore blockage, improving the electrolyte wettability and electrolyte retention of the separator, and further reducing the risk of battery failure during use. It is also beneficial for further improving the cycle performance of the battery.

[0141] In some embodiments, the average diameter of the first fiber material may be less than or equal to 100 nm, and may be selected as 25 nm to 75 nm.

[0142] In some embodiments, the average diameter of the second fiber material can be 12nm-40nm, and optionally 15nm-32nm.

[0143] By adjusting the average diameter of the first fiber material and / or the second fiber material within the aforementioned range, it is beneficial for the first and second fiber materials to overlap and form a dendritic structure. It is also beneficial for the first and second fiber materials to overlap with the filler particles to form an integrated coating, reducing the content of free filler particles. This is beneficial for improving the heat resistance of the separator, reducing the problem of separator pore blockage, improving the electrolyte wettability and electrolyte retention of the separator, and further reducing the risk of battery failure during use. It is also beneficial for further improving the cycle performance of the battery.

[0144] In some embodiments, the aspect ratio of the first fiber material may be greater than that of the second fiber material.

[0145] By further increasing the aspect ratio of the first fiber material to be greater than that of the second fiber material, it is beneficial for the first fiber material to connect more filler particles, and for the second fiber material to better connect between the first fibers, allowing the first and second fibers to overlap and form a dendritic structure. It also facilitates the overlap of the first and second fibers with the filler particles to form an integrated coating, reducing the content of free filler particles. This improves the heat resistance of the separator, reduces pore clogging, and enhances the electrolyte wettability and electrolyte retention of the separator. Therefore, by further increasing the aspect ratio of the first fiber material to be greater than that of the second fiber material, the risk of battery failure during use can be further reduced, and the cycle performance of the battery can be further improved.

[0146] In some embodiments, the aspect ratio of the first fiber material can be 12-100, and optionally 20-50.

[0147] In some embodiments, the aspect ratio of the second fiber material can be 10-70, and optionally 15-40.

[0148] By adjusting the aspect ratio of the first fiber material and / or the second fiber material within the above-mentioned range, it is beneficial for the first fiber material and the second fiber material to overlap and form a dendritic structure. It is also beneficial for the first fiber material, the second fiber material and the filler particles to overlap and form an integrated coating, reducing the content of free filler particles. This is beneficial for improving the heat resistance of the separator, reducing the problem of separator pore blockage, improving the electrolyte wettability and electrolyte retention of the separator, and further reducing the risk of battery failure during use. It is also beneficial for further improving the cycle performance of the battery.

[0149] The average length and average diameter of the first and second fiber materials can be determined by the following method: A 3.6 mm × 3.6 mm sample is cut from a randomly selected area of ​​the separator. The microstructure of the coating in the sample is mapped using a scanning electron microscope (e.g., ZEISS Sigma 300). A high vacuum mode is selected, with a working voltage of 3 kV and a magnification of 30,000x to obtain a SEM image. Based on the obtained SEM image, multiple (e.g., more than 5) test areas are selected for length statistics. Each test area has a size of 0.5 μm × 0.5 μm. The average length of the first fiber material obtained from each test area is then taken as the average length of the first fiber material, and the average length of the second fiber material obtained from each test area is taken as the average length of the second fiber material. Based on the obtained SEM image, a Nano... The Measurer particle size distribution statistical software selects multiple (e.g., more than 5) test areas to count the diameter. The size of each test area is 0.5μm×0.5μm. Then, the average diameter of the first fiber material obtained from each test area is taken as the average diameter of the first fiber material, and the average diameter of the second fiber material obtained from each test area is taken as the average diameter of the second fiber material.

[0150] In some embodiments, the first fiber material and the second fiber material may each independently include at least one of organic fiber material and inorganic fiber material.

[0151] Alternatively, the organic fiber material may include at least one of cellulose nanofibers, polytetrafluoroethylene nanofibers, and polyamide nanofibers.

[0152] Alternatively, the inorganic fiber material may include at least one of halloysite nanotubes, nanorod alumina, nanorod boehmite, nanorod silica, and glass fiber.

[0153] In some embodiments, the first fiber material and the second fiber material may each independently comprise nanocellulose.

[0154] Nanocellulose refers to cellulose with any dimension within the nanometer range (e.g., within 100 nm). It possesses both the characteristics of cellulose and those of nanoparticles. Nanocellulose can be a high-molecular-weight nanomaterial extracted from natural sources such as wood and cotton through one or more chemical, physical, or biological methods. It has advantages such as wide availability, low cost, biodegradability, high modulus, and high specific surface area. Therefore, it is an excellent substitute for traditional petrochemical resources and can effectively alleviate environmental pollution and the shortage of petrochemical resources.

[0155] Nanocellulose exhibits excellent high-temperature resistance and minimal volume change upon heating, thereby improving the heat resistance of the separator. Its low density also reduces battery mass and increases energy density. The abundant hydroxyl groups in nanocellulose allow it to bond with filler particles and porous substrates via hydrogen bonds and van der Waals forces, enhancing adhesion between coatings and between the coating and the porous substrate, thus reducing powder shedding. Furthermore, the structure formed by the overlap of nanocellulose and filler particles can possess micropores, reducing current leakage and enabling the separator to maintain good electrolyte wettability and retention, as well as excellent voltage breakdown resistance.

[0156] Optionally, the nanocellulose includes a modifying group, which may include at least one of an amino group, a carboxyl group, an aldehyde group, a sulfonic acid group, and a phosphate group, and more preferably at least one of a sulfonic acid group and a phosphate group.

[0157] When nanocellulose has the aforementioned specific modifying groups, it can effectively improve the heat resistance of the separator, enhance the thermal stability of the battery, and reduce the risk of battery failure during use. On the other hand, it can also improve the bonding strength between the coating and the porous substrate.

[0158] When nanocellulose possesses the aforementioned specific modifying groups, it facilitates the integration of nanocellulose with filler particles to form an integrated coating. This results in a stable spatial network structure in the coating, which improves the electrolyte wettability and liquid retention of the separator, enhances its ion transport characteristics and voltage breakdown resistance, and also facilitates the matching of high-voltage positive electrode active materials, further increasing the battery's energy density. Furthermore, the presence of the modifying groups reduces the proportion of hydroxyl groups, resulting in a suitable viscosity for the coating slurry, which is more conducive to coating application, thereby improving the separator's production efficiency and enhancing the uniformity and consistency of the coating.

[0159] Optionally, the nanocellulose includes hydroxyl groups and modified groups, and the molar ratio of the modified groups to the hydroxyl groups can be from 1:4 to 4:1, or more preferably from 2:3 to 7:3.

[0160] When the molar ratio of modified groups to hydroxyl groups is within the above range, the heat resistance, ion transport characteristics, electrolyte wettability and liquid retention of the separator can be further improved, which helps to reduce the risk of battery failure during use and also helps to improve the cycle performance of the battery.

[0161] The types of modifying groups in nanocellulose can be determined using infrared spectroscopy. For example, the infrared spectrum of the material can be tested to identify its characteristic peaks, thereby determining the types of modifying groups. Specifically, the material can be analyzed using infrared spectroscopy with instruments and methods known in the art, such as an infrared spectrometer (e.g., the Nicolet IS10 Fourier transform infrared spectrometer) according to the General Rules for Infrared Spectroscopic Analysis in GB / T 6040-2019.

[0162] The molar ratio of modified groups to surface hydroxyl groups in nanocellulose can be determined by the following method: The hydroxyl values ​​(equivalent to milligrams of potassium hydroxide per gram of sample) of the raw cellulose and nanocellulose are tested according to the phthalic anhydride method in GB / T12008.3-2009. The resulting values ​​are in mg KOH / g, which are then converted to mmol / g as the hydroxyl content. The content of modified groups (i.e., the content of modified hydroxyl groups) is obtained by subtracting the hydroxyl content of nanocellulose from the hydroxyl content of the raw cellulose. The molar ratio of modified groups to surface hydroxyl groups can then be calculated.

[0163] In some embodiments, nanocellulose can be obtained by: providing cellulose powder with a whiteness of ≥80%; mixing and reacting the obtained cellulose powder with a modification solution, washing to remove impurities, adjusting the pH to neutral, and then grinding and cutting to obtain nanocellulose.

[0164] Optionally, the cellulose powder with a whiteness of ≥80% can be obtained commercially or by chemical methods (e.g., acid hydrolysis, alkali treatment, Tempo catalytic oxidation), biological methods (e.g., enzymatic treatment), or mechanical methods (e.g., ultrafine grinding, ultrasonic crushing, high-pressure homogenization). The fiber raw materials used to prepare the cellulose powder with a whiteness of ≥80% may include at least one of plant fibers, such as cotton fibers (e.g., cotton fiber, kapok fiber), hemp fibers (e.g., sisal fiber, ramie fiber, jute fiber, flax fiber, hemp fiber, abaca fiber, etc.), palm fiber, wood fiber, bamboo fiber, and grass fiber.

[0165] In some embodiments, the cellulose powder with a whiteness of ≥80% can also be prepared by the following method: after the fiber raw material is opened and slag is removed, it is cooked with an alkaline solution (e.g., an aqueous solution of NaOH, the concentration of which can be 4wt% to 20wt%, optionally 5wt% to 15wt%), and then sequentially subjected to water washing to remove impurities (e.g., water washing 3 to 6 times), bleaching (e.g., sodium hypochlorite and / or hydrogen peroxide can be used), acid washing to remove impurities, water washing to remove impurities, water removal, and air drying to obtain cellulose powder.

[0166] In some embodiments, the modified solution may be an acid solution (e.g., an aqueous solution of sulfuric acid, an aqueous solution of phosphoric acid, or an aqueous solution of acetic acid) or an alkaline solution (e.g., an organic solvent solution of urea). Optionally, the modified solution is an acid solution.

[0167] Optionally, the concentration of the acid solution can be from 5 wt% to 80 wt%. When the modifying solution is an aqueous sulfuric acid solution, the concentration of the acid solution can be from 40 wt% to 80 wt%, thereby obtaining cellulose powder with sulfonic acid groups. When the modifying solution is an aqueous phosphoric acid solution, the concentration of the acid solution can be from 45 wt% to 75 wt%, thereby obtaining cellulose powder with phosphoric acid groups. When the modifying solution is an aqueous acetic acid solution, the concentration of the acid solution can be from 40 wt% to 80 wt%, thereby obtaining cellulose powder with carboxylic acid groups.

[0168] Optionally, the urea organic solvent solution can be a urea xylene solution, thereby obtaining cellulose powder with amine groups.

[0169] In some embodiments, the mass ratio of cellulose powder to modified solution may optionally be 1:2.5 to 1:50, or optionally 1:5 to 1:30.

[0170] When sulfuric acid aqueous solution is used as the modifying solution, the mass ratio of cellulose powder to acid solution can be 1:5 to 1:30. When phosphoric acid aqueous solution is used as the modifying solution, the mass ratio of cellulose powder to acid solution can be 1:5 to 1:30. When acetic acid aqueous solution is used as the modifying solution, the mass ratio of cellulose powder to acid solution can be 1:5 to 1:30. When urea organic solvent solution is used as the modifying solution, the mass ratio of cellulose powder to urea organic solvent solution can be 1:4 to 1:40.

[0171] In some embodiments, when the modified solution is an acidic solution, the reaction can be carried out at a temperature not exceeding 80°C, preferably at a temperature between 30°C and 60°C, and the reaction time between the cellulose powder and the modified solution can be from 0.25 h to 4 h, preferably from 0.5 h to 3 h.

[0172] In some embodiments, when the modified solution is an alkaline solution, the reaction can be carried out at 100°C to 145°C, and the reaction time between the cellulose powder and the modified solution can be 0.5 h to 5 h.

[0173] In some embodiments, grinding can be performed using a grinding machine, and cutting can be performed using a high-pressure homogenizer. By adjusting the grinding parameters of the grinding machine (e.g., grinding times, grinding time, etc.) and the cutting parameters of the high-pressure homogenizer, nanocellulose with different average diameters and / or different average lengths can be obtained.

[0174] In some embodiments, the content of the first fiber material may be less than the content of the second fiber material.

[0175] By adjusting the content of the first fiber material to be less than that of the second fiber material, more of the second fiber material can be better connected between the first fiber materials. This facilitates the formation of a dendritic structure with more branches, which in turn allows the electrolyte to quickly wet the separator along the first and second fiber materials, improving the electrolyte wettability and liquid retention of the separator, and further improving the cycle performance of the battery.

[0176] Optionally, the content of the first fiber material is denoted as W. 11 The content of the second fiber material is denoted as W. 12 All figures are based on the total mass of the coating, W 11 / W 12 It can be 0.20-0.95, or optionally 0.40-0.75.

[0177] By further adjusting W 11 / W 12 Within the aforementioned range, the performance of the separator and the battery can be further improved.

[0178] In some embodiments, the content of the first fiber material is denoted as W. 11 Based on the total mass of the coating, W 11 It can be 5wt%-13wt%.

[0179] In some embodiments, the content of the second fiber material is denoted as W. 12 Based on the total mass of the coating, W 12 It can be 9wt%-21wt%.

[0180] By adjusting the content of the first fiber material and / or the second fiber material within the above range, the first fiber material and the second fiber material can be better overlapped, which is beneficial to increasing the heat resistance of the separator, reducing the content of free filler particles in the coating, and also beneficial to the electrolyte quickly wetting the separator along the first fiber material and the second fiber material, thereby improving the electrolyte wettability and liquid retention of the separator.

[0181] In some embodiments, the particulate filler may include a first filler and a second filler, wherein the average particle size D1 of the first filler may be smaller than the average particle size D2 of the second filler.

[0182] The first filler has a small particle size, and the gaps between the particles after accumulation are usually small, which is conducive to forming a capillary-like effect, thereby improving the electrolyte wetting speed of the separator. However, the separator's air permeability, electrolyte retention capacity, and ion transport capacity are not excellent, which can easily lead to increased internal resistance of the battery and increased self-heating during battery use. By making the particulate filler include both the first filler and the second filler, and making the average particle size D1 of the first filler smaller than the average particle size D2 of the second filler, a certain space can be formed around the second filler particles in the coating. This can improve the air permeability of the separator and also help retain the wetting electrolyte, thereby improving the electrolyte retention and ion transport characteristics of the separator.

[0183] The second filler particles are relatively large, and the gaps between them after accumulation are usually large. When the battery is abnormally heated, the second filler particles will come into contact with each other as the porous substrate shrinks, resulting in insufficient heat resistance of the separator. By making the granular filler include both the first and second fillers, and making the average particle size D1 of the first filler smaller than the average particle size D2 of the second filler, the first filler particles can fill the gaps between the second filler particles, thereby reducing the thermal shrinkage of the separator and improving its heat resistance.

[0184] Optionally, the average particle size D1 of the first packing and the average particle size D2 of the second packing satisfy D2 / D1≥1.2.

[0185] Optionally, D2 / D1 can be 1.5-16, or more preferably 2-8.

[0186] By further adjusting D2 / D1 within the aforementioned range, the performance of the separator can be improved, giving it good air permeability, good electrolyte wettability and liquid retention, as well as good heat resistance. It can also allow the first and second fillers to better overlap with the first and second fiber materials to form an integrated coating, reducing the content of free filler particles. This can further reduce the risk of battery failure during use and further improve the battery's cycle performance.

[0187] In some embodiments, the first filler has a secondary particle morphology, and the second filler has a primary particle morphology.

[0188] The secondary particles are formed by the aggregation of multiple primary particles, and the primary filler with the secondary particle morphology can better overlap with the primary and secondary fiber materials to form an integrated coating. This helps to give the coating a stable spatial network structure, which helps to improve the heat resistance of the separator. The secondary filler with the primary particle morphology helps to reduce the moisture content of the coating, improve the air permeability and ion conductivity of the coating, thereby helping to improve the cycle performance of the battery.

[0189] In some embodiments, the ratio L1 / D2 of the average length L1 of the first fiber material to the average particle size D2 of the second filler can be 3.0-5.0.

[0190] The first fiber material is mainly used to connect the second filler particles with larger particle sizes, and it can also connect the first filler particles with smaller particle sizes. By keeping L1 / D2 within the above range, the first fiber material in the coating can connect more second filler particles, which is beneficial for forming an integrated coating, and thus helps to improve the heat resistance, electrolyte wettability and liquid retention of the separator.

[0191] In some embodiments, the ratio L2 / D1 of the average length L2 of the second fiber material to the average particle size D1 of the first filler can be 2.0-4.0.

[0192] The second fiber material is used to connect the first filler particles, which have smaller particle sizes. By keeping L2 / D1 within the above range, the second fiber material in the coating can connect more second filler particles, which is beneficial for forming an integrated coating and thus for improving the heat resistance, electrolyte wettability, and liquid retention of the separator.

[0193] In some embodiments, the average particle size D1 of the first filler may be less than 200 nm, and may be selected as 50 nm-185 nm.

[0194] The average particle size of the first filler is within the above range, making it easier to overlap with the first and second fiber materials to form an integrated coating, thereby improving the heat resistance, electrolyte wettability and liquid retention of the separator.

[0195] In some embodiments, the average particle size D2 of the second filler can be 200nm-800nm, and optionally 210nm-400nm.

[0196] The average particle size of the second filler is within the above range, which helps the coating maintain a stable pore structure during long-term charge and discharge, reduces the moisture content of the coating, improves the air permeability and ion conductivity of the coating, and thus helps improve the cycle performance of the battery.

[0197] The average particle size of the first and second fillers can be tested using equipment and methods known in the art. For example, the microstructure of the porous coating in the sample can be mapped using a scanning electron microscope (e.g., ZEISS Sigma 300). Referring to JY / T 0584-2020, a scanning electron microscope (SEM) image of the porous coating of the separator membrane can be obtained. The longest diagonal length of the particles can be measured from the SEM image, and then the average value can be taken. The number of selected particles can be more than 100.

[0198] In some embodiments, the average particle size of the primary particles constituting the first filler can be 10nm-50nm, and optionally 15nm-35nm.

[0199] If the average particle size of the primary particles constituting the first filler is within the above-mentioned range, the first filler can have a good secondary particle morphology, which is beneficial to improving the bonding effect between the first filler and the first fiber material and the second fiber material.

[0200] In some embodiments, the specific surface area of ​​the first packing may be greater than that of the second packing.

[0201] The first filler has a larger specific surface area and better affinity with the first and second fiber materials, which can make the coating have a more stable spatial network structure, and give the separator membrane better heat resistance and higher ion conductivity; the second filler has a smaller specific surface area, which is beneficial to reducing the moisture content of the separator membrane.

[0202] In some embodiments, the specific surface area of ​​the first packing can be greater than or equal to 20 m². 2 / g, optional 30m 2 / g-80m 2 / g.

[0203] When the specific surface area of ​​the first filler is within the above-mentioned range, it is beneficial to further improve the heat resistance and ion conductivity of the separator. In addition, it is also beneficial to improve the affinity between the first filler and the first fiber material and the second fiber material, so that the coating can have a more stable spatial network structure, and thus the separator has better heat resistance and higher ion conductivity.

[0204] In some embodiments, the specific surface area of ​​the second packing may be less than 20 m². 2 / g, optional 5m 2 / g-15m 2 / g.

[0205] The specific surface area of ​​the second filler is within the above range, which helps to reduce the moisture content of the separator, thereby reducing the battery capacity decay rate and improving the battery cycle performance.

[0206] The specific surface areas of the first and second packing materials have a well-known meaning in the art and can be determined using instruments and methods known in the art. For example, they can be measured using the nitrogen adsorption specific surface area analysis method according to GB / T 19587-2017, and calculated using the BET (Brunauer-Emmett-Teller) method. Optionally, the nitrogen adsorption specific surface area analysis can be performed using a Tri-Star 3020 specific surface area and pore size analyzer from Micromeritics, USA.

[0207] In some embodiments, the content of the first filler can be greater than the content of the second filler. This is beneficial for better utilizing the functions of the first and second fillers, improving the heat resistance of the separator, and also improving the electrolyte retention of the separator.

[0208] Optionally, the content of the first filler is denoted as W. 21 The content of the second filler is denoted as W. 22 All figures are based on the total mass of the coating, W 22 / W 21 It can be 0.10-0.80, or optionally 0.25-0.50.

[0209] In some embodiments, the content of the first filler is denoted as W. 21 Based on the total mass of the coating, W 21 Available in 20wt%-70wt%, with an optional range of 36wt%-61.5wt%.

[0210] The content of the first filler within the above range is beneficial for the coating slurry to have a suitable viscosity, which is more conducive to coating; in addition, it is also beneficial for the coating to have a more stable spatial network structure, thereby enabling the separator to have better heat resistance and higher ion conductivity.

[0211] In some embodiments, the content of the second filler is denoted as W. 22 All figures are based on the total mass of the coating, W 22 Available in 5wt%-60wt%, with an optional range of 10wt%-35wt%.

[0212] The content of the second filler is within the above range, which is beneficial for the coating to maintain a stable pore structure during long-term charge and discharge, thereby reducing the moisture content of the separator and preserving the electrolyte after impregnation, thus improving the cycle performance of the battery.

[0213] In some embodiments, the total content W1 of the fiber material can be 14wt%-35wt%, optionally 15wt%-30wt%, based on the total mass of the coating. W1 = W 11 +W 12 .

[0214] In some embodiments, the total content of particulate filler W2 can be greater than or equal to 60 wt%, optionally 68 wt%-83 wt%, based on the total mass of the coating. W2 = W 21 +W 22 .

[0215] By adjusting the total content of fiber materials and the total content of particulate fillers within the above range, the coating slurry can have a suitable viscosity, which is more conducive to coating. In addition, it is also conducive to the first fiber material, the second fiber material and the first filler and the second filler overlapping to form an integrated coating, thereby enabling the coating to have a more stable spatial network structure, which can further improve the heat resistance, air permeability, electrolyte wettability and liquid retention of the separator.

[0216] In some embodiments, the first filler may include at least one of inorganic particles and organic particles.

[0217] Optionally, the inorganic particles may include at least one of boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon oxide, tin dioxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, hafnium dioxide, cerium oxide, zirconium titanate, barium titanate, and magnesium fluoride. More preferably, the inorganic particles may include at least one of boehmite, alumina, barium sulfate, magnesium oxide, silicon oxide, titanium oxide, zinc oxide, cerium oxide, and barium titanate.

[0218] Alternatively, the organic particles may include at least one of polystyrene and polyacrylic wax.

[0219] In some embodiments, the first filler includes inorganic particles with secondary particle morphology, and the crystal form of the inorganic particles with secondary particle morphology may include at least two of the following: α crystal form, θ crystal form, γ crystal form, and η crystal form. Optionally, the crystal form of the inorganic particles with secondary particle morphology may include at least two of the following: α crystal form, θ crystal form, and γ crystal form.

[0220] Optionally, the content of α-crystalline secondary particle morphology inorganic particles in the secondary particle morphology inorganic particles can be greater than or equal to 1.2 wt%, and more preferably from 1.2 wt% to 10 wt%, based on the total mass of the secondary particle morphology inorganic particles.

[0221] Optionally, the content of inorganic particles with the θ-type secondary particle morphology in the inorganic particles with the secondary particle morphology can be greater than or equal to 50 wt%, and more preferably 60 wt% to 85 wt%, based on the total mass of the inorganic particles with the secondary particle morphology.

[0222] Optionally, the content of γ-crystalline secondary particle morphology inorganic particles in the secondary particle morphology inorganic particles can be greater than or equal to 10 wt%, and more preferably 15 wt% to 60 wt%, based on the total mass of the secondary particle morphology inorganic particles.

[0223] Optionally, the content of the inorganic particles with the η-crystal secondary particle morphology in the inorganic particles with the secondary particle morphology can be less than or equal to 5 wt%, and more preferably less than or equal to 2 wt%, based on the total mass of the inorganic particles with the secondary particle morphology.

[0224] Theta-type inorganic particles possess moderate specific surface area and hardness, thus enabling them to better improve both the heat resistance and ion conductivity of the separator simultaneously; gamma-type and η-type inorganic particles have the advantage of large specific surface area. Selecting different crystal forms of the first filler helps to improve at least one of the following properties of the separator: heat resistance, ion conductivity, adhesion strength, electrolyte wettability, and electrolyte retention.

[0225] In some embodiments, inorganic particles with secondary particle morphology can be prepared by the following method: an inorganic particle precursor solution is oxidized by high-pressure sputtering, then heated at 600°C to 1200°C (e.g., 1 hour to 3 hours) to form inorganic particles with primary particle morphology, and then dried and shaped at 150°C to 250°C (e.g., 30 minutes to 60 minutes) to obtain inorganic particles with secondary particle morphology (obtained by primary particle assembly).

[0226] In some embodiments, the second filler may include at least one of inorganic particles having a dielectric constant of 5 or higher, inorganic particles having ion conductivity but not storing ions, and inorganic particles capable of undergoing electrochemical reactions.

[0227] Optionally, inorganic particles having a dielectric constant of 5 or higher may include boehmite, alumina, zinc oxide, silicon oxide, titanium oxide, zirconium oxide, barium oxide, calcium oxide, magnesium oxide, nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hydropyrite, zirconium titanate, barium titanate, Pb(Zr,Ti)O3 (abbreviated as PZT), and Pb 1-m La m Zr 1-n Ti n O3 (abbreviated as PLZT, 0 < m < 1, 0 < n < 1), Pb (Mg3Nb) 2 / 3 The coating comprises at least one of PbTiO3 (abbreviated as PMN-PT) and its respective modified inorganic particles. Optionally, the modification of each inorganic particle can be chemical modification and / or physical modification. Chemical modification methods include coupling agent modification (e.g., using silane coupling agents, titanate coupling agents, etc.), surfactant modification, polymer grafting modification, etc. Physical modification methods can include mechanical dispersion, ultrasonic dispersion, high-energy treatment, etc. Modification treatment can reduce the agglomeration of inorganic particles, thereby enabling the coating to have a more stable and uniform spatial network structure; in addition, by selecting coupling agents, surfactants or polymers with specific functional groups to modify inorganic particles, it is also helpful to improve the electrolyte wettability and liquid retention of the coating, and improve the adhesion of the coating to porous substrates.

[0228] Optionally, inorganic particles that are ion-conductive but do not store ions may include Li3PO4, lithium titanium phosphate (Li), etc. x1 Ti y1 (PO4)3, Lithium aluminum titanium phosphate (Li) x2 Al y2 Ti z1 (PO4)3、(LiAlTiP) x3 O y3 Type glass, lithium lanthanum titanate (Li) x4 La y4 TiO3, lithium germanium thiophosphate (Li) x5 Ge y5 P z2 S w Lithium nitride (Li) x6 N y6 SiS2 type glass Li x7 Si y7 S z3 and P2S5 type glass Li x8 P y8 S z4 At least one of the following: 0 < x1 < 2, 0 < y1 < 3, 0 < x2 < 2, 0 < y2 < 1, 0 < z1 < 3, 0 < x3 < 4, 0 < y3 < 13, 0 < x4 < 2, 0 < y4 < 3, 0 < x5 < 4, 0 < y5 < 1, 0 < z2 < 1, 0 < w < 5, 0 < x6 < 4, 0 < y6 < 2, 0 < x7 < 3, 0 < y7 < 2, 0 < z3 < 4, 0 < x8 < 3, 0 < y8 < 3, 0 < z4 < 7. This can further improve the ion conductivity of the separator.

[0229] Optionally, the inorganic particles capable of undergoing electrochemical reactions may include at least one of lithium-containing transition metal oxides, lithium-containing phosphates, carbon-based materials, silicon-based materials, tin-based materials, and lithium-titanium compounds.

[0230] In some embodiments, the second filler may include inorganic particles with a primary particle morphology, and the crystal form of the inorganic particles with the primary particle morphology may include at least one of α crystal form and γ crystal form, optionally including α crystal form.

[0231] Optionally, the content of α-crystalline inorganic particles with primary particle morphology in the primary particle morphology can be greater than or equal to 90 wt%, and more preferably 95 wt% to 100 wt%, based on the total mass of the primary particle morphology inorganic particles.

[0232] Alpha-crystalline inorganic particles have advantages such as high hardness, good heat resistance, low dielectric constant, high safety and high true density, which can further improve the heat resistance of the coating.

[0233] The θ-type inorganic particles exhibit diffraction peaks at 2θ values ​​of 36.68°±0.2° and 31.21°±0.2° in their X-ray diffraction patterns determined using an X-ray diffractometer. The γ-type inorganic particles exhibit diffraction peaks at 2θ values ​​of 66.95°±0.2° and 45.91°±0.2° in their X-ray diffraction patterns. The η-type inorganic particles exhibit diffraction peaks at 2θ values ​​of 31.89°±0.2° and 19.37°±0.2° in their X-ray diffraction patterns. The α-type inorganic particles exhibit diffraction peaks at 2θ values ​​of 57.48°±0.2° and 43.34°±0.2° in their X-ray diffraction patterns.

[0234] The X-ray diffraction pattern of inorganic particles can be obtained by the following method: After drying the inorganic particles, grind them in a mortar (such as an agate mortar) for 30 minutes, and then use an X-ray diffractometer (such as a Miniflex 600-C) to obtain the X-ray diffraction pattern. During the test, a Cu target, a Ni filter, a tube voltage of 40 kV, a tube current of 15 mA, and a continuous scanning range of 5°–80° can be used.

[0235] In some embodiments, the coating may further include a non-particulate binder. This application does not impose any particular limitation on the type of non-particulate binder; any known material with good adhesion can be selected. Optionally, the non-particulate binder may include an aqueous solution-based binder, which has the advantages of good thermodynamic stability and environmental friendliness, thereby facilitating the preparation and application of the coating slurry. As an example, the aqueous solution-based binder may include at least one of aqueous solution-based acrylic resins (e.g., homopolymers of acrylic acid, methacrylic acid, sodium acrylate monomers, or copolymers with other comonomers), polyvinyl alcohol (PVA), isobutylene-maleic anhydride copolymers, and polyacrylamide.

[0236] Optionally, the content of non-particulate binder in the coating can be less than or equal to 2 wt%, based on the total mass of the coating. The fibrous materials and particulate fillers in the coating can form a stable spatial network structure, thereby enabling the release membrane to maintain high adhesion while reducing the amount of binder used.

[0237] In some embodiments, the coating thickness can be less than or equal to 3 μm, optionally 0.3 μm-2 μm, and more preferably 0.5 μm-1.2 μm. This is beneficial for improving the energy density of the battery. The coating thickness refers to the thickness of the coating located on one side of the porous substrate.

[0238] The embodiments of this application do not impose any particular limitation on the material of the porous substrate. Any known substrate with good chemical and mechanical stability can be selected. For example, the porous substrate may include at least one of porous polyolefin-based resin membranes (e.g., polyethylene, polypropylene, polyvinylidene fluoride), porous aramid membranes, porous polyimide membranes, porous glass fibers, and porous nonwoven fabrics. The porous substrate can be a single-layer film or a multi-layer composite film. When the porous substrate is a multi-layer composite film, the materials of each layer can be the same or different.

[0239] In some embodiments, the thickness of the porous substrate may be less than or equal to 5 μm, and may be selected as 3 μm-4.5 μm.

[0240] In some embodiments, the separator may further include an adhesive layer disposed on at least a portion of the coating surface. The adhesive layer not only prevents the coating from peeling off and improves battery reliability, but also improves the interface between the separator and the electrodes (e.g., positive and negative electrodes), thereby contributing to improved battery cycle performance.

[0241] In some embodiments, the adhesive layer may include a particulate adhesive. Optionally, the particulate adhesive may include at least one of acrylate monomer homopolymers or copolymers, acrylate monomer homopolymers or copolymers, and fluorinated olefin monomer homopolymers or copolymers.

[0242] The comonomer may include, but is not limited to, at least one of the following: acrylate monomers, acrylic monomers, olefin monomers, halogenated olefin monomers, fluoroether monomers, etc.

[0243] Optionally, the particulate binder may comprise vinylidene fluoride polymers, such as homopolymers of vinylidene fluoride monomer (VDF) and / or copolymers of vinylidene fluoride monomer and comonomers. The comonomer may be at least one of olefin monomers, fluorinated olefin monomers, chlorinated olefin monomers, acrylate monomers, acrylic monomers, and fluoroether monomers. Optionally, the comonomer may comprise at least one of the following: trifluoroethylene (VF3), trifluorochloroethylene (CTFE), 1,2-difluoroethylene, tetrafluoroethylene (TFE), hexafluoropropylene (HFP), perfluoro(alkyl vinyl) ethers (e.g., perfluoro(methyl vinyl) ether PMVE, perfluoro(ethyl vinyl) ether PEVE, perfluoro(propyl vinyl) ether PPVE), perfluoro(1,3-m-dioxane), and perfluoro(2,2-dimethyl-1,3-m-dioxane) (PDD).

[0244] In some embodiments, the heat shrinkage rate of the separator at 150°C for 1 hour can be less than 2% in both the transverse and longitudinal directions.

[0245] The separator has a low thermal shrinkage rate at high temperatures, which improves the reliability of the battery.

[0246] In some embodiments, the air permeability of the separator membrane can be less than or equal to 300s / 100mL, and can be selected as 100s / 100mL-240s / 100mL.

[0247] The separator has good air permeability, which can improve the ion conductivity of the separator and the performance of battery capacity.

[0248] In some embodiments, the wetting rate of the separator can be greater than or equal to 3 mm / s, and can be selected as 5 mm / s-15 mm / s.

[0249] The separator has good electrolyte wettability, which can improve the ion conductivity of the separator and the battery capacity performance.

[0250] The heat shrinkage rate and air permeability of the separator have meanings known in the art and can be measured using methods known in the art. For example, they can be tested in accordance with GB / T 36363-2018.

[0251] The wetting rate of the separator has a meaning known in the art and can be measured using methods known in the art. An exemplary test method is as follows: Cut the separator into samples with a width of 5 mm and a length of 100 mm, fix both ends of the sample, and place it horizontally; drop 0.5 mg of electrolyte into the center of the sample, and after a specified time (1 min in this application), take a photograph and measure the length of electrolyte diffusion to obtain the wetting rate of the separator. To ensure the accuracy of the test results, multiple samples (e.g., 5 to 10) can be tested, and the test results are obtained by calculating the average value. The electrolyte can be prepared as follows: Mix ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a mass ratio of 30:50:20 to obtain an organic solvent, and dissolve fully dried LiPF6 in the above organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0252] It should be noted that the coating parameters (such as thickness) of the aforementioned separator are coating parameters for one side of the porous substrate. When the coating is applied to both sides of the porous substrate, if the coating parameters on either side meet the requirements of this application, it is considered to fall within the protection scope of this application.

[0253] [Preparation Method]

[0254] This application also provides a method for preparing the above-mentioned separator membrane.

[0255] The method includes the following steps: providing a porous substrate; mixing a first fiber material, a second fiber material, and particulate filler in a solvent in a predetermined ratio to prepare a coating slurry; applying the coating slurry to at least one surface of the porous substrate and drying it to obtain a release film.

[0256] In some embodiments, the solvent used when preparing the coating slurry can be water, such as deionized water.

[0257] In some embodiments, the coating slurry may also include other components, such as dispersants, wetting agents, binders, surfactants, etc.

[0258] In some embodiments, a coating machine may be used to apply the coating slurry. This application does not impose any particular limitation on the type of coating machine; for example, a commercially available coating machine may be used. The coating machine may include a gravure roller; the gravure roller is used to transfer the slurry onto a porous substrate.

[0259] In some embodiments, the preparation method may further include the following steps: applying a slurry containing particulate adhesive to at least a portion of the surface of the coating, and drying it to form an adhesive layer.

[0260] The raw materials and their content parameters used in the preparation method of the separator membrane can be referred to the separator membrane mentioned above, and will not be repeated here.

[0261] Unless otherwise specified, all raw materials used in the preparation of the separator membrane can be obtained commercially.

[0262] [Positive electrode plate]

[0263] In some embodiments, the positive electrode may include a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector and comprising a positive electrode active material. For example, the positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0264] When the battery is a lithium-ion battery, the positive electrode active material may include, but is not limited to, at least one of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, at least one of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their respective modified compounds. Examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their respective modified compounds.

[0265] In some embodiments, to further improve the energy density of the battery, the positive electrode active material for lithium-ion batteries may include materials with the general formula Li. a Ni b Co c M d O e A f At least one of lithium transition metal oxides and their modified compounds. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes, but is not limited to, at least one of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes, but is not limited to, at least one of N, F, S and Cl.

[0266] As an example, positive electrode active materials for lithium-ion batteries may include, but are not limited to, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.8 Co 0.15 Al 0.05 At least one of O2, LiFePO4, and LiMnPO4.

[0267] When the battery is a sodium-ion battery, the positive electrode active material may include, but is not limited to, at least one of sodium-containing transition metal oxides, polyanionic materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue materials.

[0268] As an example, the positive electrode active material used in sodium-ion batteries may include, but is not limited to, NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, and NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue materials, with the general formula X p M' q (PO4) r O x Y 3-x At least one of the materials in general formula X. p M' q (PO4) r O x Y 3-x In this case, 0 < p ≤ 4, 0 < q ≤ 2, 1 ≤ r ≤ 3, 0 ≤ x ≤ 2, and X includes, but is not limited to, H. + Li + Na + K + and NH4 + At least one of the following, M' is a transition metal cation, optionally including but not limited to at least one of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halide anion, optionally at least one of F, Cl and Br.

[0269] The modified compounds for the above-mentioned positive electrode active materials can be obtained by doping and / or surface coating of the positive electrode active materials.

[0270] In some embodiments, the positive electrode film may optionally include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include, but is not limited to, at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0271] In some embodiments, the positive electrode film layer may optionally include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0272] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include, but is not limited to, at least one of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0273] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing positive electrode active materials, optional positive electrode conductive agents, optional positive electrode binders, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to it.

[0274] [Negative electrode plate]

[0275] In some embodiments, the negative electrode sheet may include a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector and comprising a negative electrode active material. For example, the negative current collector has two surfaces opposite each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative current collector.

[0276] The negative electrode active material may be any negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include, but are not limited to, at least one of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include, but are not limited to, at least one of elemental tin, tin oxide, and tin alloys.

[0277] In some embodiments, the negative electrode film layer may optionally include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include, but is not limited to, at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0278] In some embodiments, the negative electrode film layer may optionally include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0279] In some embodiments, the negative electrode film layer may optionally include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0280] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, copper foil may be used. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include, but is not limited to, at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0281] The negative electrode film is typically formed by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, optional negative electrode conductive agent, optional negative electrode binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0282] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet also includes a conductive undercoat layer (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In some embodiments, the negative electrode sheet of this application also includes a protective layer covering the surface of the negative electrode film layer.

[0283] Electrolyte

[0284] The electrolyte plays a role in conducting ions between the positive and negative electrode plates.

[0285] In some embodiments, the electrolyte may include an electrolyte salt and a solvent.

[0286] When the battery is a lithium-ion battery, as an example, the electrolyte salt may include, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0287] When the battery is a sodium-ion battery, as an example, the electrolyte salt may include, but is not limited to, at least one of sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalate borate (NaDFOB), sodium dioxalate borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorodioxalate phosphate (NaDFOP), and sodium tetrafluorooxalate phosphate (NaTFOP).

[0288] In some embodiments, the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl ester carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0289] In some embodiments, the electrolyte may also include additives, for example, which may include, but are not limited to, one or more of fluoroethylene carbonate (FEC), 1,3-propanesulfonate lactone (PS), and vinylene carbonate (VC).

[0290] Optionally, the total mass of the additives can be 0.5wt%-12wt% of the total mass of the electrolyte, and optionally 2wt%-8wt%.

[0291] Methods for preparing battery cells are well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a battery cell. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with the aforementioned electrolyte. After vacuum sealing, settling, and formation processes, a battery cell is obtained. Multiple battery cells can further be connected in series, parallel, or a combination thereof to form a battery module. Multiple battery modules can also be connected in series, parallel, or a combination thereof to form a battery pack. In some embodiments, multiple battery cells can also be directly assembled into a battery pack.

[0292] This application also provides an electrical device, which includes the battery provided in this application embodiment. The battery can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device can be, but is not limited to, mobile devices (such as mobile phones, tablets, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0293] Electrical devices can choose the type of battery according to their usage needs, such as individual battery cells, battery modules, or battery packs.

[0294] Figure 6 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0295] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0296] Example

[0297] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0298] The nanocellulose used in this application can be commercially available or prepared by the following method.

[0299] Preparation of nanocellulose

[0300] After the cotton linters are opened and the slag is removed by a cotton opener, they are cooked at 150°C for 2 hours using a 5wt% NaOH aqueous solution. Then, the cotton cellulose powder with a whiteness of ≥85% is obtained by sequentially washing and removing impurities (washing 3 times), bleaching with sodium hypochlorite, washing and removing impurities with dilute hydrochloric acid, washing and removing impurities (washing 1 time), water removal, and air drying.

[0301] 1 kg of the obtained cotton cellulose powder was mixed with 30 kg of 60 wt% sulfuric acid aqueous solution and reacted at 55℃ to 60℃ for 0.5 h to 1.5 h. After the reaction, the mixture was washed with water to remove impurities (washed 3 times), filtered, and deacidified and depurified. The pH was then adjusted to neutral with 10 wt% NaOH aqueous solution. The mixture was then ground with a grinder and then nano-cut using a high-pressure homogenizer to obtain nanocellulose with sulfonic acid modified groups. The molar ratio of sulfonic acid groups to surface hydroxyl groups was between 3:3 and 5:3.

[0302] During the preparation process, nanocellulose with different average diameters and / or different average lengths can be obtained by adjusting the reaction concentration, reaction time, grinding mill parameters, and cutting parameters of high-pressure homogenizer equipment, and these nanocelluloses can be used as the first nanocellulose and the second nanocellulose, respectively.

[0303] Example 1

[0304] Preparation of positive electrode sheet

[0305] LiNi, the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2, conductive agent acetylene black, and binder polyvinylidene fluoride are mixed in a mass ratio of 94:3:3, and an appropriate amount of solvent NMP is added. The mixture is stirred evenly to obtain a positive electrode slurry. The positive electrode slurry is coated on both surfaces of the positive electrode current collector aluminum foil, and after drying, cold pressing, and slitting, a positive electrode sheet is obtained.

[0306] Preparation of negative electrode sheet

[0307] Artificial graphite (anode active material), acetylene black (conductive agent), styrene-butadiene rubber (SBR) (binder), and sodium carboxymethyl cellulose (CMC) (mass ratio 95:2:2:1) are mixed evenly in an appropriate amount of deionized water to obtain a cathode slurry. The cathode slurry is coated onto copper foil (anode current collector), and after drying, cold pressing, and slitting, a cathode sheet is obtained.

[0308] Preparation of the separating membrane

[0309] Porous PE substrate is available: 4.5μm thick.

[0310] Preparation of coating slurry: Mix the first fiber material, the second fiber material, the first filler, the second filler, and the binder polyacrylic acid in a mass ratio of 10:18:52:18:2 in an appropriate amount of deionized water to obtain the coating slurry.

[0311] The first fiber material uses first nanocellulose, with an average length of 1500 nm, an average diameter of 50 nm, and an aspect ratio of 30.

[0312] The second fiber material uses second nanocellulose, with an average length of 350 nm, an average diameter of 20 nm, and an aspect ratio of 17.5.

[0313] The first filler is alumina with a secondary particle morphology and a volume distribution particle size Dv50 of 140 nm. The contents of α-crystal, θ-crystal, γ-crystal and η-crystal in the alumina are 1.1 wt%, 68.7 wt%, 29.6 wt% and 0.6 wt%, respectively, based on the total mass of alumina.

[0314] The second filler is alumina with a primary particle morphology, a volume distribution particle size Dv50 of 320 nm, and the alumina crystal form is mainly α crystal, with a content of more than 99 wt%, based on the total mass of alumina.

[0315] Coating: The prepared coating slurry is applied to both surfaces of the PE porous substrate using a microgravure process. After drying and slitting, a release film is obtained. The coating thickness on one side of the PE porous substrate is 0.75 μm.

[0316] Preparation of electrolyte

[0317] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 20:80 to obtain an organic solvent. Fully dried LiPF6 was dissolved in the organic solvent to prepare an electrolyte with a concentration of 1 mol / L. Then, fluoroethylene carbonate (FEC) and 1,3-propanesulfonic acid lactone (PS) were added. The mass content of FEC was 3 wt% of the total mass of the electrolyte, and the mass content of PS was 0.5 wt% of the total mass of the electrolyte.

[0318] Battery manufacturing

[0319] The positive electrode, separator, and negative electrode are stacked and wound in sequence to obtain the electrode assembly. The electrode assembly is placed in an outer aluminum shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, the battery is obtained.

[0320] Example 2

[0321] The battery was prepared using a method similar to that in Example 1, except that the second fiber material used in the preparation of the separator had an average length of 250 nm, an average diameter of 20 nm, and an aspect ratio of 12.5.

[0322] Example 3

[0323] The battery was prepared using a method similar to that in Example 1, except that the average length of the second fiber material in the preparation of the separator was 550 nm, the average diameter was 20 nm, and the aspect ratio was 27.5.

[0324] Example 4

[0325] The battery was prepared using a method similar to that in Example 1, except that the average length of the first fiber material in the preparation of the separator was 850 nm, the average diameter was 50 nm, and the aspect ratio was 17.

[0326] Example 5

[0327] The battery was prepared using a method similar to that in Example 1, except that the average length of the first fiber material in the preparation of the separator was 1050 nm, the average diameter was 50 nm, and the aspect ratio was 21.

[0328] Example 6

[0329] The battery was prepared using a method similar to that in Example 1, except that the average length of the first fiber material in the preparation of the separator was 2000 nm, the average diameter was 50 nm, and the aspect ratio was 40.

[0330] Example 7

[0331] The battery was prepared using a method similar to that in Example 1, except that the average length of the first fiber material in the preparation of the separator was 3000 nm, the average diameter was 50 nm, and the aspect ratio was 60.

[0332] Example 8

[0333] The battery was prepared using a method similar to that in Example 1, except that in the preparation of the separator, the mass ratio of the first fiber material, the second fiber material, the first filler, the second filler, and the binder polyacrylic acid was 15:13:52:18:2.

[0334] Comparative Example 1

[0335] The battery was prepared using a method similar to that in Example 1, except that no second fiber material was added to the coating slurry when preparing the separator, and the mass ratio of the first fiber material, the first filler, the second filler, and the binder polyacrylic acid was 28:52:18:2.

[0336] Performance testing

[0337] (1) Battery thermal performance test

[0338] At 25℃, the batteries were charged at a constant current of 1C to 4.2V, and then charged at a constant voltage until the current was less than or equal to 0.05C, and allowed to stand for 5 minutes. Then, each battery was tested in a DHG-9070ADHG series high-temperature oven with fixtures, increasing the temperature from 25℃ to 60℃±2℃ at a rate of 5℃ / min and holding for 30 minutes. Afterward, the temperature was increased again at a rate of 5℃ / min, with each 5℃ increase followed by a 30-minute holding period. The oven temperature at which the battery failed and the holding time were recorded. A higher oven failure temperature indicates better thermal stability. For batteries with the same oven failure temperature, a longer holding time indicates better thermal stability. For accuracy, the average of five parallel samples was used as the test result.

[0339] (2) Battery cycle performance test

[0340] At 25℃, the battery was charged at a constant current of 0.33C to 4.2V, and then charged at a constant voltage until the current was less than or equal to 0.05C. At this point, the battery was fully charged, and the charging capacity was recorded, which is the first charge capacity. After the battery was left to stand for 5 minutes, it was discharged at a constant current of 1C to 2.8V. This completes one charge-discharge cycle, and the discharge capacity was recorded, which is the first discharge capacity. The battery was subjected to cyclic charge-discharge tests using the above method, and the discharge capacity after each cycle was recorded. The capacity retention rate (%) of the battery after 1000 cycles at 25℃ = discharge capacity after 1000 cycles / discharge capacity of the first cycle × 100%. For accuracy, the average value of 5 parallel samples was taken as the test result.

[0341] The test results of Examples 1 to 8 and Comparative Example 1 are shown in Table 1.

[0342] As shown in Table 1, by making the fiber material in the separator coating include both the first fiber material and the second fiber material, and by making the average length L1 of the first fiber material and the average length L2 of the second fiber material satisfy L1 > 800 nm and L1 / L2 ≥ 2.4, the battery can have high thermal stability and good cycle performance.

[0343] The test results from Examples 1 to 7 also show that by further adjusting one or more of the following: the average length L1 of the first fiber material, the average length L2 of the second fiber material, the average particle size D1 of the first filler, the average particle size D2 of the second filler, L1 / L2, L1 / D2, and L2 / D1, the thermal stability and cycle performance of the battery can be further improved.

[0344] The test results of Examples 1 and 8 also show that by making the content of the first fiber material in the separator coating less than the content of the second fiber material, the cycle performance of the battery can be further improved.

[0345] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

[0346]

Claims

1. A separator membrane comprising a porous substrate and a coating layer provided on at least one surface of the porous substrate, characterized in that, The coating comprises a fibrous material and a particulate filler, the fibrous material comprises a first fibrous material and a second fibrous material, both of the first fibrous material and the second fibrous material are organic fibrous materials, the organic fibrous material comprises nanocellulose, the average length of the first fibrous material is denoted as L1, the average length of the second fibrous material is denoted as L2, L1 is greater than 800 nm, L2 is 200 nm-800 nm, and L1 / L2 is 2.4-9.

0.

2. The separator film according to claim 1, characterized by L1 / L2 is 2.7-8.

6.

3. The separator membrane according to claim 2, characterized in that L1 / L2 is 2.7-5.

8.

4. The separator film according to claim 1, characterized in that, the average length L1 of the first fibrous material is 850 nm-3000 nm.

5. The separator film according to claim 1, characterized in that, the average length L1 of the first fibrous material is 1000 nm-2000 nm; and / or, the average length L2 of the second fibrous material is 300 nm-550 nm.

6. The separator membrane according to any one of claims 1 to 5, characterized in that, The average diameter of the first fibrous material is greater than the average diameter of the second fibrous material.

7. The separator membrane according to claim 6, characterized in that The average diameter of the first fibrous material is less than or equal to 100 nm.

8. The separator membrane according to claim 7, characterized in that The average diameter of the first fibrous material is 25 nm-75 nm.

9. The separator membrane of claim 6, wherein, The average diameter of the second fibrous material is 12 nm-40 nm.

10. The separator membrane according to claim 9, characterized in that, The average diameter of the second fibrous material is 15 nm-32 nm.

11. The separator membrane according to any one of claims 1 to 5, characterized in that, The aspect ratio of the first fibrous material is greater than the aspect ratio of the second fibrous material.

12. The separator membrane of claim 11, wherein, The aspect ratio of the first fibrous material is 12-100.

13. The separator membrane of claim 12, wherein, The aspect ratio of the first fibrous material is 20-50.

14. The separator membrane of claim 11, wherein, The aspect ratio of the second fibrous material is 10-70.

15. The separator membrane of claim 14, wherein, The aspect ratio of the second fibrous material is 15-40.

16. The separator membrane according to any one of claims 1 to 5, wherein The content of the first fibrous material is less than the content of the second fibrous material.

17. The separator membrane of claim 16, wherein, The content of the first fibrous material is denoted W 11 , the content of the second fibrous material is denoted W 12 , each based on the total mass of the coating, W 11 / W 12 is 0.20-0.

95.

18. The separator membrane of claim 17, wherein, W 11 / W 12 0.40-0.

75.

19. The separator membrane of claim 16, wherein, The content of the first fibrous material is denoted W 11 , based on the total mass of the coating, W 11 is 5-13 wt%.

20. The separator membrane of claim 16, wherein, The content of the second fibrous material is denoted W 12 , based on the total mass of the coating, W 12 is 9 wt% - 21 wt%.

21. The separator film according to claim 1, characterized in that, the nanocellulose comprises a modifying group, the modifying group comprises at least one of an amine group, a carboxyl group, an aldehyde group, a sulfonic acid group and a phosphoric acid group.

22. The separator membrane of claim 21, wherein, The modifying group comprises at least one of a sulfonic acid group and a phosphoric acid group.

23. The separator membrane of claim 1, wherein, The nanocellulose comprises a hydroxyl group and a modifying group, and the molar ratio of the modifying group to the hydroxyl group is 1:4 to 4:

1.

24. The separator membrane of claim 23, wherein, The molar ratio of the modifying group to the hydroxyl group is 2:3 to 7:

3.

25. The separator membrane of claim 1, wherein, The particulate filler comprises a first filler and a second filler, the average particle size D1 of the first filler is less than the average particle size D2 of the second filler.

26. The separator membrane of claim 25, wherein, The average particle size D1 of the first filler and the average particle size D2 of the second filler satisfy D2 / D1≥1.

2.

27. The separator membrane of claim 26, wherein, D2 / D1 is 1.5-16.

28. The separator membrane of claim 27, wherein, D2 / D1 is 2-8.

29. The separator membrane of claim 25, wherein, The first filler is a secondary particle morphology, and the second filler is a primary particle morphology.

30. The separator film according to claim 25, characterized in that, the ratio L1 / D2 of the average length L1 of the first fibrous material to the average particle size D2 of the second filler is 3.0-5.0; and / or, the ratio L2 / D1 of the average length L2 of the second fibrous material to the average particle size D1 of the first filler is 2.0-4.

0.

31. The separator of claim 25, wherein an average particle size Dl of the first filler is less than 200 nm; and / or an average particle size D2 of the second filler is 200 nm to 800 nm.

32. The separator of claim 31, wherein an average particle size Dl of the first filler is 50 nm to 185 nm; and / or an average particle size D2 of the second filler is 210 nm to 400 nm.

33. The separator membrane of claim 29, wherein, an average particle size of primary particles constituting the first filler is 10 nm to 50 nm.

34. The separator membrane of claim 33, wherein, an average particle size of primary particles constituting the first filler is 15 nm to 35 nm.

35. The separator membrane of claim 25, wherein, a specific surface area of the first filler is larger than a specific surface area of the second filler.

36. The separator membrane of claim 35, wherein, The specific surface area of the first filler is greater than or equal to 20 m 2 / g.

37. The separator membrane of claim 36, wherein, The specific surface area of the first filler is 30 m 2 / g - 80 m 2 / g.

38. The separator membrane of claim 35, wherein, The specific surface area of the second filler is less than 20 m 2 / g.

39. The separator membrane of claim 38, wherein, The specific surface area of the second filler is 5 m 2 / g-15 m 2 / g.

40. The separator membrane of claim 25, wherein, a content of the first filler is larger than a content of the second filler.

41. The separator membrane of claim 40, wherein, The content of the first filler is denoted by W 21 , the content of the second filler is denoted by W 22 , each based on the total mass of the coating, W 22 / W 21 is 0.10 to 0.

80.

42. The separator membrane of claim 41, wherein, W 22 / W 21 0.25-0.

50.

43. The separator membrane of claim 40, wherein, The content of the first filler is denoted W 21 , based on the total mass of the coating 21 is 20 wt% - 70 wt%.

44. The separator membrane of claim 43, wherein, W 21 is 36 wt% - 61.5 wt%.

45. The separator membrane of claim 40, wherein, The content of the second filler is denoted as W 22 , based on the total mass of the coating 22 is 5 wt% - 60 wt%.

46. The separator membrane of claim 45, wherein, W 22 is 10 wt% to 35 wt%.

47. The separator of claim 25, wherein the first filler includes at least one of inorganic particles and organic particles; and / or the second filler includes at least one of inorganic particles having a dielectric constant of 5 or more, inorganic particles having ionic conductivity but not storing ions, and inorganic particles capable of electrochemical reaction.

48. The separator membrane of claim 47, wherein, the first filler includes at least one of inorganic particles and organic particles, and the inorganic particles include at least one of boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon oxide compound, tin dioxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, hafnium dioxide, cerium oxide, zirconium titanate, barium titanate, and magnesium fluoride, and the organic particles include at least one of polystyrene and polyacrylic acid wax.

49. The separator membrane of claim 48, wherein, the inorganic particles include at least one of boehmite, alumina, barium sulfate, magnesium oxide, silicon oxide compound, titanium oxide, zinc oxide, cerium oxide, and barium titanate.

50. The separator membrane of claim 25, wherein, the first filler includes inorganic particles of secondary particle morphology, and crystal forms of the inorganic particles of secondary particle morphology include at least two of α crystal form, θ crystal form, γ crystal form, and η crystal form.

51. The separator membrane of claim 50, wherein, the crystal forms of the inorganic particles of secondary particle morphology include at least two of α crystal form, θ crystal form, and γ crystal form.

52. The separator membrane of claim 50, wherein, a content of the inorganic particles of secondary particle morphology of α crystal form in the inorganic particles of secondary particle morphology is 1.2 wt% or more, based on a total mass of the inorganic particles of secondary particle morphology.

53. The separator membrane of claim 52, wherein, a content of the inorganic particles of secondary particle morphology of α crystal form in the inorganic particles of secondary particle morphology is 1.2 wt% to 10 wt%, based on a total mass of the inorganic particles of secondary particle morphology.

54. The separator membrane of claim 50, wherein, a content of the inorganic particles of secondary particle morphology of θ crystal form in the inorganic particles of secondary particle morphology is 50 wt% or more, based on a total mass of the inorganic particles of secondary particle morphology.

55. The separator membrane of claim 54, wherein, a content of the inorganic particles of secondary particle morphology of θ crystal form in the inorganic particles of secondary particle morphology is 60 wt% to 85 wt%, based on a total mass of the inorganic particles of secondary particle morphology.

56. The separator membrane of claim 50, wherein, a content of the inorganic particles of secondary particle morphology of γ crystal form in the inorganic particles of secondary particle morphology is 10 wt% or more, based on a total mass of the inorganic particles of secondary particle morphology.

57. The separator membrane of claim 56, wherein, The content of the secondary particle-shaped inorganic particles of the γ crystal form in the secondary particle-shaped inorganic particles is 15 wt% to 60 wt% based on the total mass of the secondary particle-shaped inorganic particles.

58. The separator membrane of claim 50, wherein, The content of the secondary particle-shaped inorganic particles of the η crystal form in the secondary particle-shaped inorganic particles is less than or equal to 5 wt% based on the total mass of the secondary particle-shaped inorganic particles.

59. The separator membrane of claim 58, wherein, The content of the secondary particle-shaped inorganic particles of the η crystal form in the secondary particle-shaped inorganic particles is less than or equal to 2 wt% based on the total mass of the secondary particle-shaped inorganic particles.

60. The separator membrane of claim 25, wherein, The second filler includes primary particle-shaped inorganic particles, and the crystal form of the primary particle-shaped inorganic particles includes at least one of an α crystal form and a γ crystal form.

61. The separator membrane of claim 60, wherein, The crystal form of the primary particle-shaped inorganic particles includes an α crystal form.

62. The separator membrane of claim 60, wherein, The content of the primary particle-shaped inorganic particles of the α crystal form in the second filler is greater than or equal to 90 wt% based on the total mass of the second filler.

63. The separator membrane of claim 62, wherein, The content of the primary particle-shaped inorganic particles of the α crystal form in the second filler is 95 wt% to 100 wt% based on the total mass of the second filler.

64. The separator membrane of claim 1, wherein, The coating further includes a non-particulate binder.

65. The separator membrane of claim 64, wherein, The non-particulate binder includes an aqueous solution type binder.

66. The separator membrane of claim 64, wherein, The content of the non-particulate binder in the coating is less than or equal to 2 wt% based on the total mass of the coating.

67. The separator membrane of claim 1, wherein, The separator film further includes a bonding layer disposed on at least a portion of the surface of the coating.

68. The separator membrane of claim 67, wherein, The bonding layer includes a particulate binder.

69. The separator membrane of claim 68, wherein, The particulate binder includes at least one of an acrylate monomer homopolymer or copolymer, an acrylic monomer homopolymer or copolymer, and a fluorine-containing olefin monomer homopolymer or copolymer.

70. The separator membrane of claim 1, wherein The separator film satisfies at least one of the following conditions (1) to (5): (1) the thickness of the porous substrate is less than or equal to 5 μm; (2) the thickness of the coating is less than or equal to 3 μm; (3) the separator film has a transverse and longitudinal heat shrinkage of less than 2% at 150°C for 1 hour; (4) the separator film has an air permeability of less than or equal to 300 s / 100 mL; (5) the separator film has a wetting speed of greater than or equal to 3 mm / s.

71. The separator membrane of claim 70, wherein, The separator film satisfies at least one of the following conditions (1) to (4): (1) the thickness of the porous substrate is 3 μm to 4.5 μm; (2) the thickness of the coating is 0.3 μm to 2 μm; (3) the air permeability of the separator film is 100 s / 100 mL to 240 s / 100 mL; (4) the wetting speed of the separator film is 5 mm / s to 15 mm / s.

72. A battery, comprising: The separator film according to any one of claims 1 to 71.

73. An electrical device, comprising: The battery according to claim 72.

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