Isolating membrane and preparation method thereof, battery and electric device

Abstract

The invention discloses an isolating membrane and a preparation method thereof, a battery and an electric device. The isolating membrane comprises a base membrane and a coating, the coating comprises a fluorine-containing carbon material, a solid electrolyte and / or a metal oxide, the coating is arranged on at least one side of the two sides, distributed in the thickness direction, of the base membrane, and / or the coating is arranged in the middle of the base membrane in the thickness direction of the base membrane. Therefore, dendritic crystal growth can be inhibited, and the dendritic crystal puncture resistance of the isolating membrane can be improved, so that the risk that the isolating membrane is punctured by dendritic crystals and short circuit occurs in the battery can be reduced.

Description

Technical Field

[0001] This application belongs to the field of batteries, and more specifically, relates to a separator, a method for preparing the same, a battery, and an electrical device. Background Art

[0002] As an energy storage device, batteries are widely used in various fields. Taking lithium-ion batteries as an example, they have the characteristics of being green, environmentally friendly, high-energy, and low-carbon. They are not only used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric vehicles, and ships, as well as in many fields such as military equipment and aerospace. With the development of current society, people's requirements for batteries are also getting higher and higher. Summary of the Invention

[0003] In view of the technical problems existing in the background art, this application provides a separator, aiming to inhibit dendrites from piercing the separator.

[0004] To achieve the above object, a first aspect of this application provides a separator, which includes:

[0005] A base film and a coating, the coating includes a fluorocarbon material, as well as a solid electrolyte and / or a metal oxide. The coating is provided on at least one of the two sides of the base film distributed along its thickness direction, and / or, the coating is provided in the middle of the base film along its thickness direction.

[0006] The separator of this application has the following beneficial effects: It can inhibit the growth of dendrites and improve the dendrite puncture resistance of the separator, thereby reducing the risk of dendrites piercing the separator and internal short circuit of the battery.

[0007] In some embodiments of this application, the general formula of the fluorocarbon material is CFx, where 0.85 ≤ x ≤ 1.5, and optionally, 1 ≤ x ≤ 1.25. This is beneficial to further improving the performance of the battery.

[0008] In some embodiments of this application, the fluorocarbon material includes at least one of fluorinated graphite, fluorinated carbon black, fluorinated carbon, fluorinated graphene, fluorinated carbon nanotubes, and fluorinated carbon fibers. Thus, the risk of the separator being pierced by dendrites can be reduced.

[0009] In some embodiments of this application, the particle size of the fluorocarbon material is 50 nm to 5 μm, and can be 50 nm to 1 μm. Meeting the given conditions is beneficial to improving the uniformity and adhesion effect of the coating, and is also beneficial to making the separator have good ion transport ability.

[0010] In some embodiments of the present application, the volume particle size Dv50 of the fluorocarbon material is 50 nm to 1000 nm, and may be optionally 50 nm to 500 nm. This is beneficial for further balancing the uniformity of the coating and the ion transport ability of the separator membrane.

[0011] In some embodiments of the present application, the volume particle size Dv90 of the fluorocarbon material is ≤ 3 μm, and may be optionally ≤ 1 μm. This is beneficial for further balancing the uniformity of the coating and the ion transport ability of the separator membrane.

[0012] In some embodiments of the present application, the areal density of the coating is 3.5 g / m 2 ~15 g / m 2 ; and / or, the areal density of the fluorocarbon material in the coating is 2 g / m 2 ~14.5 g / m 2 .

[0013] In some embodiments of the present application, based on the mass of the fluorocarbon material, the total mass percentage content of the solid electrolyte and / or the metal oxide is ≤ 70%, and may be optionally 20% to 50%. This is beneficial for further reducing the risk of the separator membrane being pierced by dendrites and balancing a good ion transport ability.

[0014] In some embodiments of the present application, the wetting angles of the solid electrolyte and the metal oxide are each independently ≤ 15°. This can improve the affinity between the separator membrane and the strongly polar electrolyte solution and the problem that the separator membrane is easily pierced by dendrites.

[0015] In some embodiments of the present application, the ionic conductivity of the solid electrolyte at 25 °C is ≥ 10 -4 S / cm. Meeting the given conditions can further improve the ion transport ability of the separator membrane and inhibit the growth of lithium dendrites.

[0016] In some embodiments of the present application, the lithium intercalation capacity of the metal oxide is ≥ 600 mAh / g. This is beneficial for further improving the puncture resistance of the separator membrane and inhibiting the growth of lithium dendrites.

[0017] In some embodiments of the present application, the solid electrolyte includes at least one of an oxide electrolyte, a sulfide electrolyte, and an acid salt electrolyte. Optionally, it includes Li 7 La 3 Zr 2 O 12 , Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 , Li 1.5 Al 0.5 Ge1.5 (PO 4 ) 3 、Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 、LiTi 2 (PO 4 ) 3 、Li 3 PS 4 、Li 10 GeP 2 S 12 、Li 6 PS 5 at least one of Cl. This is conducive to further improving the puncture resistance of the separator and inhibiting the growth of lithium dendrites.

[0018] In some embodiments of the present application, the metal oxide includes at least one of oxides of Fe, oxides of Sn, oxides of Ti, oxides of Cu, oxides of Mn, oxides of Al, oxides of Ge, oxides of Zr, oxides of Zn. This can preferably inhibit the formation of dendrites.

[0019] In some embodiments of the present application, the coating further includes: a lithium supplement material. This is also conducive to making up for the possible minor capacity loss caused by the consumption of lithium by the coating.

[0020] In some embodiments of the present application, based on the mass of the fluorocarbon-containing material, the mass percentage content of the lithium supplement material ≤ 25%. This is both conducive to making up for the possible minor capacity loss of the battery caused by the consumption of lithium by the coating, and conducive to avoiding the risk of weakening the inhibition effect of the coating on the growth of lithium dendrites caused by excessive use of the lithium supplement material.

[0021] In some embodiments of the present application, the lithium supplement material includes at least one of LiF, Li 3 N, Li coated with M 2 O, Li x O coated with Li 2 Si, where M includes at least one of Fe, Co, Ni, Mn, and the value range of x is 0.5 - 3.75. This is conducive to achieving a better lithium supplement effect at a lower dosage.

[0022] In some embodiments of the present application, the coating further includes: at least one of a binder, a dispersant, a thickener.

[0023] In some embodiments of the present application, based on the mass of the coating, the coating satisfies at least one of the following conditions: the mass percentage content of the binder is 0.5% to 5%, optionally 1% to 3%; the mass percentage content of the dispersant is ≤2%, optionally 1% to 1.5%; the mass percentage content of the thickener is ≤2%, optionally 1% to 1.5%.

[0024] In some embodiments of the present application, the thickness of a single layer of the coating is 1.5 μm to 3.5 μm, optionally 1.5 μm to 3 μm. This can not only improve the ability of the separator to resist dendrite piercing, but also reduce the risks of problems such as an increase in the reversible capacity loss of the battery and a decrease in the battery energy density that may be caused by an overly large coating thickness.

[0025] In some embodiments of the present application, the total thickness of the coating is ≤5 μm. This is beneficial for further reducing the risks of problems such as an increase in the reversible capacity loss of the battery and a decrease in the battery energy density that may be caused by an overly large coating thickness.

[0026] In some embodiments of the present application, the ratio of the total thickness of the coating to the thickness of the base film is 1:(2.5 to 10). Meeting the given conditions can take into account both the dendrite piercing resistance of the separator and the energy density of the battery.

[0027] In some embodiments of the present application, the coating is provided only on at least one of the two sides of the base film distributed along its thickness direction. The two sides of the base film distributed along its thickness direction are respectively close to the positive electrode plate and the negative electrode plate, and the coating is provided on the side of the base film close to the negative electrode plate. This can achieve a better effect of inhibiting dendrite growth.

[0028] In some embodiments of the present application, the coating is provided only on at least one of the two sides of the base film distributed along its thickness direction, and the thickness of the coating provided on the side of the base film close to the negative electrode plate is ≥ the thickness of the coating provided on the side of the base film close to the positive electrode plate. This can achieve a better effect of inhibiting dendrite growth.

[0029] In some embodiments of the present application, the coating is provided only on at least one of the two sides of the base film distributed along its thickness direction, and the thickness of the base film is ≥7 μm.

[0030] In some embodiments of the present application, the coating is provided only in the middle of the base film along its thickness direction, and the thicknesses of the base film on both sides of the coating along its thickness direction are respectively independently ≤9 μm, optionally 5 μm to 9 μm. This is beneficial for taking into account the energy density of the battery while improving the puncture resistance of the separator.

[0031] In some embodiments of the present application, the coating is only provided in the middle of the base film along its thickness direction, and the coating includes a lithium supplement material. Based on the mass of the fluorocarbon material, the mass percentage content of the lithium supplement material is ≤10%. Meeting the given conditions can balance the dendrite puncture resistance of the separator and the energy density of the battery.

[0032] In some embodiments of the present application, the puncture strength of the separator is ≥350 gf, optionally ≥450 gf.

[0033] In some embodiments of the present application, the electronic conductivity of the coating at 25 °C is 10 -6 mS / cm to 10 - 10 mS / cm.

[0034] A second aspect of the present application provides a method for preparing the separator of the first aspect of the present application, which includes: forming a coating on at least one side of the two sides of the base film distributed along its thickness direction; and / or forming the coating in the middle of the base film along its thickness direction, the coating includes a fluorocarbon material, and a solid electrolyte and / or a metal oxide. The separator prepared by this method is beneficial to inhibiting dendrite growth and improving the dendrite puncture resistance of the separator.

[0035] In some embodiments of the present application, coating raw materials including a fluorocarbon material, a solid electrolyte and / or a metal oxide, and an adhesive are mixed with a solvent to obtain a coating slurry.

[0036] In some embodiments of the present application, the coating slurry is coated on at least one side of the two sides of the base film distributed along its thickness direction to obtain the coating; or, the base film includes a first base film and a second base film, the coating slurry is coated on one side of the two sides of the first base film distributed along its thickness direction to form the coating, and the second base film is stacked on the side of the coating away from the first base film.

[0037] A third aspect of the present application provides a battery, which includes: the separator of the first aspect of the present application, and / or a separator prepared by the method for preparing a separator of the second aspect of the present application.

[0038] A fourth aspect of the present application provides an electrical device, which includes: the battery of the third aspect of the present application.

[0039] The additional aspects and advantages of the present application will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of the present application. Description of the Drawings

[0040] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0041] Figure 1 is a schematic structural diagram of a separator according to an embodiment of the present application.

[0042] Figure 2 is a schematic structural diagram of a separator according to another embodiment of the present application.

[0043] Figure 3 is a schematic structural diagram of a separator according to yet another embodiment of the present application.

[0044] Figure 4 is a schematic structural diagram of a battery according to an embodiment of the present application.

[0045] Figure 5 is a schematic structural diagram of a battery module according to an embodiment of the present application.

[0046] Figure 6 is a schematic structural diagram of a battery pack according to an embodiment of the present application.

[0047] Figure 7 is an exploded view of a battery pack according to an embodiment of the present application.

[0048] Figure 8 is a schematic diagram of an embodiment of an electrical device using a battery as a power source according to an embodiment of the present application.

[0049] Explanation of reference numerals:

[0050] 11: base film; 11a: side of the base film close to the negative electrode tab; 11b: side of the base film close to the positive electrode tab; 111: first sub-base film; 112: second sub-base film; 12: coating; 1: battery; 2: battery module; 3: battery pack; 4: upper box body; 5: lower box body. Detailed embodiments

[0051] The present application will be further described below in conjunction with the detailed embodiments. It should be understood that these detailed embodiments are only used to illustrate the present application and not to limit the scope of the present application.

[0052] Hereinafter, embodiments of the positive electrode active material, its preparation method, positive electrode sheet, battery, and electrical device of the present application will be specifically described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary details are omitted. For example, there are cases where details of well-known matters are omitted and repeated descriptions of actually identical structures are omitted. This is to prevent the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0053] The "range" disclosed in the present application is defined in the form of a lower limit and / or an upper limit. A given range is defined by selecting a lower limit and / or an upper limit, and the selected lower limit and / or upper limit define the boundary of a particular range. The ranges defined in this way can include or exclude the end values and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form an undefined range, and any lower limit can be combined with other lower limits to form an undefined range. Similarly, any upper limit can be combined with any other upper limit to form an undefined range. In addition, each separately disclosed point or single value itself can be used as a lower limit or an upper limit and combined with any other point or single value or combined with other lower limits or upper limits to form an undefined range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, ranges of 60 to 110 and 80 to 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" have been fully listed herein, and "0 to 5" is only an abbreviated representation of these numerical combinations. Additionally, when a certain parameter is expressed as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0054] If there is no special instruction, all embodiments and alternative embodiments of the present application can be combined with each other to form a new technical solution, and such a technical solution should be considered to be included in the disclosure of the present application.

[0055] If there is no special instruction, all technical features and alternative technical features of the present application can be combined with each other to form a new technical solution, and such a technical solution should be considered to be included in the disclosure of the present application.

[0056] Unless otherwise specified, all steps of this application can be carried out sequentially or randomly, preferably sequentially.

[0057] Unless otherwise specified, the terms "comprising" and "including" mentioned in this application mean open-ended, and can also be closed-ended. For example, the said "comprising" and "including" can mean that other components not listed can also be included or comprised, or only the components listed are included or comprised.

[0058] Unless otherwise specified, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) while B is true (or exists); or both A and B are true (or exist).

[0059] Unless otherwise specified, in this application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, in this text, the character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0060] In this application, the terms "a plurality of" and "a variety of" mean two or more than two.

[0061] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification, claims and the above-mentioned drawings of this application, as well as any variations thereof, are intended to cover non-exclusive inclusion. Unless otherwise stated, the terms used in this application have the well-known meanings commonly understood by those skilled in the art. Unless otherwise stated, the numerical values of the various parameters mentioned in this application can be measured by various common measurement methods in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0062] With the continuous promotion of the green environmental protection theme, the application of batteries has penetrated into all aspects of life, including vehicles, electronic devices, energy storage devices, etc. However, with the continuous popularization of battery applications, people's requirements for batteries are also getting higher and higher. Taking lithium batteries as an example, lithium batteries, especially lithium metal batteries, face the problem of lithium dendrite growth during the cycling process, which brings the risk of dendrites piercing the separator membrane and causing short circuits, leading to thermal runaway. At present, the separators commonly used in related fields usually only play a physical barrier role. With the cycling process and dendrite growth, there is still a possibility that dendrites grow along the pores and pierce through.

[0063] In this application, by compounding a fluorocarbon material with at least one of a solid electrolyte and a metal oxide to form a coating, and making the coating formed on at least one side of the separator along its thickness direction and / or in the middle of the separator, it is not only beneficial to inhibit dendrite growth, but also can improve the dendrite-piercing resistance of the separator, thereby reducing the risk of dendrites piercing the separator and causing internal short circuits in the battery.

[0064] The separator disclosed in the embodiments of this application is applicable to secondary batteries, and the batteries disclosed in the embodiments of this application can be used in electrical equipment that uses the battery as a power source or various energy storage systems that use the battery as an energy storage element. The electrical equipment can include, but is not limited to, mobile phones, tablets, laptop computers, electric toys, power tools, battery cars, electric vehicles, ships, spacecraft, and so on. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0065] The first aspect of this application provides a separator, which includes: a base film and a coating. The coating includes a fluorocarbon material, as well as a solid electrolyte and / or a metal oxide. The coating is provided on at least one side of the base film distributed along its thickness direction, and / or the coating is provided in the middle of the base film along its thickness direction.

[0066] In this application, the fluorocarbon material refers to a carbon-based material having a carbon-fluorine covalent bond, and the solid electrolyte refers to a solid ionic conductor electrolyte. Refer to Figures 1 to 3 Understand that the separator includes a base film 11 and a coating 12. The coating 12 includes a fluorocarbon material, as well as a solid electrolyte and / or a metal oxide. The coating 12 is provided on at least one side of the base film 11 distributed along its thickness direction (refer to Figure 1 or Figure 2 Understand), and / or the coating 12 is provided in the middle of the base film 11 along its thickness direction (refer to Figure 3(Understanding). Exemplarily, the coating 12 may include a fluorocarbon material and a solid electrolyte, or may include a fluorocarbon material and a metal oxide, or may include a fluorocarbon material, a solid electrolyte, and a metal oxide at the same time. Optionally, the metal oxide may include, but is not limited to, transition metal oxides and / or oxides of metals with multiple different valence states. Among them, the material composition of the coating can be obtained by combining one or more of the conventional methods, and the conventional methods may include, but are not limited to, ICP elemental analysis, EDS energy spectrum analysis, XRD testing, XPS testing, infrared testing, atomic absorption method, etc. The position of the coating can be obtained by characterizing the microstructure of the separator cross-section with conventional instruments such as a scanning electron microscope.

[0067] In this application, the separator can be used in batteries such as lithium batteries or sodium batteries. Among them, by compounding at least one of a fluorocarbon material and a solid electrolyte (usually the solid electrolyte layer used to prepare a solid-state battery) and a metal oxide and forming a coating on the base film of the separator, it is beneficial to inhibit the generation or growth of dendrites, improve the mechanical strength of the separator, and enhance its dendrite puncture resistance, achieving a better synergistic effect. Taking a lithium-ion battery as an example, the fluorocarbon material has a high lithium intercalation capacity and lithium reaction activity, can react with Li to generate C and LiF, and has no intermediate products. This is beneficial for consuming lithium to inhibit the generation of lithium dendrites and can also react with the generated lithium dendrites to inhibit their growth. (Furthermore, forming the coating on the side of the separator facing the negative electrode sheet is beneficial for the reaction to generate a LiF interface layer, which helps to form a good and stable SEI and improve the Coulomb efficiency, which is more obvious at high rates); in addition, the solid electrolyte and the metal oxide can also react with lithium or have a certain lithium intercalation capacity, and can also consume a part of lithium, thereby inhibiting the generation and growth of lithium dendrites; moreover, the solid electrolyte also has good ion conduction ability, which can improve the ion transport ability of the coating and further inhibit the formation of lithium dendrites; further, the base film of the separator is usually a polymer. Compared with the base film, the solid electrolyte and the metal oxide have relatively better mechanical strength and heat resistance, and the oxygen that may exist in the solid electrolyte and the metal oxide can also combine with the fluorocarbon material to form a denser coating structure. Therefore, a better synergistic effect can be exerted to reduce the risk of dendrite piercing the separator and internal short circuit of the battery.

[0068] The separator of this application has the following beneficial effects: It can inhibit the growth of dendrites and improve the dendrite puncture resistance of the separator, thereby reducing the risk of dendrite piercing the separator and internal short circuit of the battery.

[0069] Furthermore, on the basis of meeting the above conditions, the separator of the first aspect of this application can optionally meet one or more of the following conditions.

[0070] In some embodiments of the present application, the general formula of the fluorocarbon material can be CFx, where 0.85 ≤ x ≤ 1.5, and optionally, 1 ≤ x ≤ 1.25.

[0071] Exemplarily, the value of x can be 0.85, 0.9, 1, 1.1, 1.2, 1.25, 1.3, 1.4, 1.5, and so on. Among them, the value of x in CFx can be obtained by combining the correlation analysis of the absorption peak area of the fluorocarbon bond and the absorption peak area of the carbon-carbon bond in the infrared spectrum. An increase in the fluorine element content (atomic percentage) in the fluorocarbon material is beneficial to obtaining improved thermal stability. In the present application, the fluorine element content in the fluorocarbon material meets the given conditions, which is beneficial to endowing the coating with good thermal stability, insulation, and ionic conduction ability, thereby further improving the performance of the battery.

[0072] In some embodiments of the present application, the fluorocarbon material can include at least one of fluorinated graphite, fluorinated carbon black, fluorinated carbon, fluorinated graphene, fluorinated carbon nanotubes, and fluorinated carbon fibers. Among them, fluorinated carbon can also include, but is not limited to, fluorinated (nano) carbon fibers, etc., and fluorinated graphite can include, but is not limited to, fluorinated graphite microflakes, etc. The fluorocarbon materials within the given range have a high lithium intercalation capacity and lithium reaction activity, and can be used in batteries such as lithium batteries or sodium batteries to inhibit dendrite growth and reduce the risk of the separator being pierced by dendrites.

[0073] In some embodiments of the present application, the particle size of the fluorocarbon material is 50 nm to 5 μm, and can be optionally 50 nm to 1 μm.

[0074] Exemplarily, the particle size of the fluorocarbon material can be 50 nm, 100 nm, 200 nm, 500 nm, 800 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, and so on. The particle size of the fluorocarbon material can be measured by conventional instruments and conventional methods such as scanning electron microscopy and particle size analyzer. Among them, an increase in the particle size of the fluorocarbon material is beneficial to reducing the risk of particle clogging of the micropores of the base film during coating formation, and further reducing the risk of ion transport channel blockage caused by the decrease in the air permeability of the separator membrane and the resulting decrease in battery capacity and cycle life; in addition, an increase in the particle size of the fluorocarbon material will also increase the viscosity of the coating slurry. Using a fluorocarbon material with a smaller particle size is not only beneficial to obtaining an appropriate viscosity of the coating slurry, reducing the risk of decreased coating uniformity and increased coating difficulty caused by a larger viscosity of the coating slurry, but also beneficial to improving the adhesion effect of the fluorocarbon material on the surface of the base film and reducing the risk of powder shedding that may occur during the coating process. The particle size of the fluorocarbon material within the given range is beneficial to coating, improving the uniformity and adhesion effect of the coating, and also beneficial to making the separator membrane have better ion transport ability. Optionally, the particle size of the fluorocarbon material can be 50 nm to 1 μm, which is beneficial to further balancing the coating uniformity and the ion transport ability of the separator membrane. Exemplarily, the air permeability of the separator membrane can be ≤ 300 s / 100 mL. Among them, when the air permeability of the separator membrane is ≤ 300 s / 100 mL, the air permeability of the separator membrane is better and has better ion transport characteristics.

[0075] In some embodiments of the present application, the volume particle size Dv50 of the fluorocarbon material can be 50 nm to 1000 nm, and can be optionally 50 nm to 500 nm. Exemplarily, the volume particle size Dv50 of the fluorocarbon material can be 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, and so on. Thus, it is beneficial to further balance the coating uniformity and adhesion effect, and make the separator membrane have better ion transport ability.

[0076] In some embodiments of the present application, the volume particle size Dv90 of the fluorocarbon material can be ≤ 3 μm, and can be optionally ≤ 1 μm. Exemplarily, the volume particle size Dv90 of the fluorocarbon material can be 100 nm to 3 μm, 200 nm to 1 μm, 500 nm to 1 μm, 300 nm, 600 nm, 800 nm, 900 nm, 1 μm, 2 μm, 3 μm, and so on. Thus, it is beneficial to further balance the coating uniformity and adhesion effect, and make the separator membrane have better ion transport ability.

[0077] In some embodiments of the present application, the particle sizes of the solid electrolyte and the metal oxide can be independently 50 nm to 5 μm, optionally independently 50 nm to 1 μm, such as can be independently 50 nm, 100 nm, 200 nm, 500 nm, 800 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, and so on. This is beneficial to further balance the uniformity of the coating and the ion transport ability of the separator membrane.

[0078] In some embodiments of the present application, the areal density of the coating can be 3.5 g / m 2 ~15 g / m 2 . Exemplarily, the areal density of the coating can be 3.5 g / m 2 、4 g / m 2 、5 g / m 2 、6 g / m 2 、7 g / m 2 、8 g / m 2 、9 g / m 2 、10 g / m 2 、11 g / m 2 、12 g / m 2 、13 g / m 2 、14 g / m 2 、15 g / m 2 , and so on. The areal density of the coating can be measured by conventional methods. For example, the areal density of the coating can be calculated by testing the weight difference of the separator membrane before and after coating peeling and the area of the separator membrane sample. The coating peeling method is not particularly limited and can include, but is not limited to, mechanical peeling method, solvent immersion method, etc. Increasing the coating thickness or coating density is beneficial to improving the dendrite puncture resistance ability of the separator membrane, and decreasing the coating thickness or coating density is beneficial to obtaining better ion transport characteristics. The areal density of the coating meeting the given range conditions is beneficial not only to reducing the risk of dendrite piercing the separator membrane but also to enabling the separator membrane to have better ion transport ability.

[0079] In some embodiments of the present application, the areal density of the fluorocarbon material in the coating can be 2 g / m 2 ~14.5 g / m 2 . Exemplarily, the areal density of the fluorocarbon material in the coating can be 2 g / m 2 、3 g / m 2 、4 g / m 2 、5 g / m 2 、6 g / m 2 、7 g / m 2 、8 g / m 2 、9 g / m 2 、10 g / m 2 、11 g / m 2 、12 g / m2 、 13 g / m 2 、 14 g / m 2 、 14.5 g / m 2 , and so on. The areal density of the fluorocarbon material in the coating can be measured by conventional methods. For example, the content relationship between the solid electrolyte and / or metal oxide and the fluorocarbon material in the coating can be analyzed by combining one or more of conventional methods such as elemental analysis and infrared testing, and then calculated in combination with the areal density of the coating. Increasing the content of the fluorocarbon material in the coating is beneficial to consuming more lithium by reacting with lithium, improving the inhibitory effect on dendrite growth. Increasing the content of the solid electrolyte and / or metal oxide in the coating is beneficial to improving the strength of the separator itself and the ability to resist dendrite piercing. When the areal density of the fluorocarbon material in the coating meets the given conditions, it is beneficial to further inhibit dendrite growth and reduce the risk of the separator being pierced by dendrites.

[0080] In some embodiments of the present application, based on the mass of the fluorocarbon material, the total mass percentage content of the solid electrolyte and / or metal oxide can be ≤ 70%, and can be optionally 20% - 50%.

[0081] Exemplarily, the total mass percentage content of the solid electrolyte and / or metal oxide can be 70%, 60%, 50%, 40%, 30%, 20%, 10%, and so on. The content relationship between the solid electrolyte and / or metal oxide and the fluorocarbon material can be analyzed by combining one or more of conventional methods such as elemental analysis and infrared testing. Increasing the content of the solid electrolyte and / or metal oxide is beneficial to further improving the mechanical strength of the separator and the ability of the separator itself to resist dendrite piercing. Making the dosage of the solid electrolyte and / or metal oxide meet the given range is not only beneficial to improving the dense structure of the coating and enhancing the ability of the separator itself to resist dendrite piercing, but also enables the coating to have a good inhibitory effect on dendrite growth. At the same time, it is also beneficial for the separator to have a good ion transport ability. Optionally, the total mass percentage content of the solid electrolyte and / or metal oxide can be 20% - 50%, which is beneficial to further reducing the risk of the separator being pierced by dendrites and having a good ion transport ability.

[0082] In some embodiments of the present application, the wetting angles of the solid electrolyte and the metal oxide can be independently ≤ 15°.

[0083] Exemplarily, the wetting angles of the solid electrolyte and the metal oxide can be 15°, 12°, 10°, 8°, 5°, etc. respectively and independently, or can be within a range composed of any of the above values respectively and independently. The wetting angles of the solid electrolyte and the metal oxide can be measured by conventional equipment and conventional methods. For example, a contact angle measuring instrument (such as Dataphysics OCA25 video optical contact angle measuring instrument, etc.) can be used to drop a water droplet of the liquid phase on the solid electrolyte or metal oxide sample, and the contact angle value can be obtained by software fitting the image contour. The fluorocarbon-containing material has strong hydrophobicity and poor affinity with the strongly polar electrolyte, which is not conducive to the separator absorbing and retaining the electrolyte. Metal oxides usually have good hydrophilicity. The oxygen-containing functional groups on their surfaces can form hydrogen bonds to improve hydrophilicity. And affected by factors such as polar hydrophilic groups, the solid electrolyte usually also exhibits strong hydrophilicity. Introducing the solid electrolyte and / or metal oxide into the coating is also beneficial for the separator to absorb and retain the electrolyte, and making the interface between the separator and the electrode sheet fully wetted by the electrolyte can also improve the problem that the separator is easily pierced by dendrites to a certain extent. Further, by making the wetting angles of the solid electrolyte and the metal oxide meet the given conditions, the affinity between the separator and the strongly polar electrolyte and the problem that the separator is easily pierced by dendrites can be further improved.

[0084] In some embodiments of the present application, the ionic conductivity of the solid electrolyte at 25 °C can be ≥ 10 -4 S / cm.

[0085] Exemplarily, the ionic conductivity of the solid electrolyte at 25 °C can be ≥ 10 -4 S / cm, ≥ 5×10 -4 S / cm, ≥ 10 -3 S / cm, ≥ 5×10 -3 S / cm, ≥ 10 -2 S / cm, etc. The ionic conductivity can be obtained by testing with the alternating current impedance method. An increase in the ionic conductivity of the solid electrolyte is beneficial to improving the ionic transport ability of the separator. Thus, meeting the given conditions can further improve the ionic transport ability of the separator and inhibit the growth of lithium dendrites.

[0086] In some embodiments of the present application, the solid electrolyte can include at least one of oxide electrolytes, sulfide electrolytes, and acid salt electrolytes.

[0087] In this application, the acid salt electrolyte refers to a solid electrolyte composed of acid salt materials (such as common acid salts like phosphates and borates), and may include but is not limited to phosphate-based solid electrolyte materials. Exemplarily, taking a lithium battery as an example, the solid electrolyte may include but is not limited to lithium lanthanum zirconium oxide (LLZO), lithium aluminum titanium phosphate (LATP), lithium titanium phosphate (LTP), lithium aluminum germanium phosphate (LAGP), lithium germanium phosphorus sulfur sulfide (LGPS), lithium thiophosphate (Li 3 PS 4 ), lithium phosphorus sulfur chloride (Li 6 PS 5 Cl), etc., and one or more of the solid electrolytes within the given range can form a dense structure in combination with a fluorocarbon-containing material, or can react with lithium to consume lithium, which is beneficial to improving the puncture resistance of the separator and inhibiting the growth of lithium dendrites. Optionally, the solid electrolyte may include but is not limited to Li 7 La 3 Zr 2 O 12 , Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 , Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 , Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 , LiTi 2 (PO 4 ) 3 , Li 3 PS 4 , Li 10 GeP 2 S 12 , Li 6 PS 5 Cl, etc., and this is beneficial to further improving the puncture resistance of the separator and inhibiting the growth of lithium dendrites.

[0088] In some embodiments of this application, the lithium intercalation capacity of the metal oxide can be ≥600 mAh / g.

[0089] Exemplarily, the lithium intercalation capacity of the metal oxide can be ≥600 mAh / g, ≥650 mAh / g, ≥700 mAh / g, ≥750 mAh / g, ≥800 mAh / g, ≥850 mAh / g, ≥900 mAh / g, and so on. The lithium intercalation capacity of the metal oxide can be represented by the reversible capacity when it is used as the negative electrode active material. It can be obtained by using it as the active material of the negative electrode sheet and assembling the battery for charge and discharge tests. A higher lithium intercalation capacity can consume more lithium, which is beneficial to further improving the inhibitory effect of the coating on dendrite growth. Thus, meeting the given conditions can not only improve the mechanical strength of the separator and enhance its puncture resistance, but also be conducive to further inhibiting the growth of lithium dendrites.

[0090] In some embodiments of the present application, the metal oxide may include at least one of oxides of Fe, Sn, Ti, Cu, Mn, Al, Ge, Zr, and Zn. The metal oxides within the given range have a certain lithium intercalation capacity or can react with lithium to consume lithium, and can preferably inhibit the growth of lithium dendrites.

[0091] In some embodiments of the present application, the coating 12 may further include: a lithium supplement material. For a lithium battery, the coating will consume a small amount of lithium due to lithium intercalation or reaction with lithium. By further incorporating a lithium supplement material, it is also beneficial to make up for the minor capacity loss that may be caused by the consumption of lithium by the coating.

[0092] In some embodiments of the present application, based on the mass of the fluorocarbon-containing material, the mass percentage content of the lithium supplement material can be ≤25%.

[0093] Exemplarily, the mass percentage content of the lithium supplement material can be 25%, 23%, 20%, 15%, 10%, 5%, and so on. The relative amounts of the lithium supplement material and the fluorocarbon-containing material can determine the specific types and contents of the fluorocarbon material and the lithium supplement material in the coating by combining conventional methods such as elemental analysis, XRD testing, and infrared testing, and can be obtained through calculation. For a lithium battery, controlling the content of the lithium supplement material within the given range is not only beneficial to making up for the minor capacity loss of the battery that may be caused by the consumption of lithium by the coating, but also can reduce the excessive self-consumption of lithium within the coating that may be caused by a relatively large amount of the lithium supplement material, resulting in a decrease in the lithium storage capacity and reaction ability outside the coating, and further weakening the risk of the inhibitory effect of the coating on the growth of lithium dendrites.

[0094] In some embodiments of the present application, the lithium supplement material may include LiF, Li 3 N, Li 2 O coated with M, Li x Si-coated Li 2At least one of O, M includes at least one of Fe, Co, Ni, Mn, and the value range of x is 0.5 to 3.75.

[0095] Exemplarily, the value of x can be 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 3.75, and so on. The specific type of the lithium supplement material can be determined by combining one or more of conventional methods such as elemental analysis, atomic absorption method, XRD test, etc. The given lithium supplement material is beneficial to achieving a good lithium supplement effect at a lower dosage. In addition, using M or Li x Si-coated Li 2 O can form a passivation layer on the surface of Li 2 O, playing a role in slow-release lithium supplementation, and at the same time can also avoid the capacity attenuation of Li 2 O caused by contact with air before addition.

[0096] In some embodiments of the present application, the coating further includes at least one of a binder, a dispersant, and a thickener. Adding a binder can improve the adhesion strength between the coating and the base film and reduce the risk of powder shedding that may exist in each component of the coating; adding a dispersant is beneficial to improving the dispersion uniformity of the coating slurry, thereby improving the uniformity of the coating; adding a thickener is beneficial to improving the stability of the coating slurry, reducing the risk of delamination or sedimentation, and improving the coating effect and uniformity of the coating. It should be noted that the binder, the dispersant, and the thickener can be respectively independently conventional selections in the relevant field, and can be prepared by conventional methods or obtained through commercial channels. For example, the binder can include but is not limited to one or more of polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), etc.; the dispersant can include but is not limited to one or more of hydrolyzed polymaleic anhydride, acrylic block polymer, polyester block polymer, polyethylene glycol type polyol, and polyethyleneimine derivative, etc.; the thickener can include but is not limited to one or more of sodium carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, polyacrylate, polyurethane, polyether, etc.

[0097] In some embodiments of the present application, based on the mass of the coating, the mass percentage content of the binder can be 0.5% to 5%, and can be optionally 1% to 3%. For example, it can be 0.5%, 1%, 2%, 3%, 4%, 5%, and so on. Thus, the adhesion strength between the coating and the base film can be effectively improved.

[0098] In some embodiments of the present application, based on the mass of the fluorocarbon-containing material, the mass percentage content of the dispersant can be ≤2%, and can be optionally 1% to 1.5%. For example, it can be 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 2%, and so on. Thus, the uniformity of the coating can be effectively improved.

[0099] In some embodiments of the present application, based on the mass of the fluorocarbon material, the mass percentage content of the thickener can be ≤2%, and can be optionally 1% - 1.5%. For example, it can be 0.5%, 1%, 2%, 3%, 4%, 5%, etc. Thus, the operability of coating application and the uniformity of the coating can be effectively improved.

[0100] In some embodiments of the present application, the thickness of the single-layer coating can be 1.5μm - 3.5μm, and can be optionally 1.5μm - 3μm.

[0101] Exemplarily, the thickness of the single-layer coating can be 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, etc. The thickness of the coating can be measured by a film thickness gauge. Meeting the given conditions can not only play a good role in improving the strength of the separator and inhibiting dendrite growth, enhancing the dendrite puncture resistance of the separator, but also obtain good processability, and at the same time reduce the risks of problems such as an increase in the reversible capacity loss of the battery and a decrease in the battery energy density that may be caused by an excessive coating thickness.

[0102] In some embodiments of the present application, the total thickness of the coating can be ≤5μm. Exemplarily, the total thickness of the coating can be 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, etc. The total thickness of the coating can be obtained by measuring the thickness of each single-sided coating with a film thickness gauge and calculating the sum. Meeting the given conditions is beneficial to further reducing the risks of problems such as an increase in the reversible capacity loss of the battery and a decrease in the battery energy density that may be caused by an excessive coating thickness on the basis of enabling the separator to have good dendrite puncture resistance.

[0103] In some embodiments of the present application, the ratio of the total thickness of the coating to the thickness of the base film can be 1:(2.5 - 10).

[0104] Exemplarily, the ratio of the total thickness of the coating to the thickness of the base film can be 1 / 2.5, 1 / 3, 1 / 4, 1 / 5, 1 / 6, 1 / 7, 1 / 8, 1 / 9, 1 / 10, etc. The thickness of the base film can also be measured by a film thickness gauge. Meeting the given conditions is beneficial to further reducing the risks of problems such as an increase in the reversible capacity loss of the battery and a decrease in the battery energy density that may be caused by an excessive coating thickness on the basis of enabling the separator to have good dendrite puncture resistance.

[0105] In some embodiments of the present application, the coating 12 can be provided on at least one of the two sides of the base film 11 distributed along its thickness direction. The two sides of the base film 11 distributed along its thickness direction are respectively close to the positive electrode plate and the negative electrode plate, and the coating 12 can be provided on the side 11a of the base film 11 close to the negative electrode plate. Reference can be made to Figure 1Understanding. Providing a coating on the side of the base film facing the negative electrode can further improve the inhibitory effect on dendrite growth.

[0106] In some embodiments of the present application, the coating 12 can be provided on at least one of the two sides of the base film 11 distributed along its thickness direction. The thickness of the coating 12 provided on the side 11a of the base film 11 close to the negative electrode can be ≥ the thickness of the coating 12 provided on the side 11b of the base film 11 close to the positive electrode. Reference can be made to Figure 2 Understanding. Providing coatings on both sides of the base film along its thickness direction is beneficial to further improve the mechanical strength and puncture resistance of the separator. Even if one side of the separator is punctured by dendrites, it is beneficial to delay the time of being completely penetrated. Optionally, the thickness of the coating 12 provided on the side 11a of the base film 11 close to the negative electrode can be greater than the thickness of the coating 12 provided on the side 11b of the base film 11 close to the positive electrode, thereby further improving the inhibitory effect on dendrite growth.

[0107] In some embodiments of the present application, the coating 12 can be provided on at least one of the two sides of the base film 11 distributed along its thickness direction. The thickness of the base film can be ≥ 7 μm. Exemplarily, the thickness of the base film can be 7 μm, 8 μm, 10 μm, 12 μm, 15 μm, etc. Meeting the given conditions is beneficial to further reduce the risk of being punctured by dendrites.

[0108] In some embodiments of the present application, the coating 12 can be provided only in the middle of the base film 11 along its thickness direction. The thicknesses of the base films on both sides of the coating 12 along its thickness direction can be independently ≤ 9 μm, and can be optionally 5 μm - 9 μm.

[0109] Reference Figure 3 Understanding, the base film 11 can include a first sub-base film 111 and a second sub-base film 112 arranged along its thickness direction, and the coating 12 can be sandwiched between the first sub-base film 111 and the second sub-base film 112. Adopting this setting can avoid direct contact between the coating and the electrode, which is beneficial to reducing the attenuation of the battery capacity that may be caused by the reaction between the solid electrolyte and / or metal oxide and lithium on the basis of improving the puncture resistance of the separator. Further, the thicknesses of the first sub-base film 111 and the second sub-base film 112 can be independently ≤ 9 μm, and can be optionally independently 5 μm - 9 μm. Exemplarily, the thicknesses of the first sub-base film 111 and the second sub-base film 112 can be independently 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, etc. Meeting the given conditions is beneficial to further taking into account the energy density of the battery on the basis of reducing the risk of the separator being punctured by dendrites.

[0110] In some embodiments of the present application, the coating 12 may be provided only in the middle of the base film 11 along its thickness direction. The coating 12 may include a lithium supplement material. Based on the mass of the fluorocarbon material, the mass percentage of the lithium supplement material may be ≤ 10%. Exemplarily, the mass percentage of the lithium supplement material may be 10%, 8%, 5%, 3%, etc. Refer to Figure 3 Understand that when the coating 12 is sandwiched between the first sub-base film 111 and the second sub-base film 112, the lithium consumption caused by the reaction of the solid electrolyte and / or metal oxide with lithium is also less. Controlling the content of the lithium supplement material within the given range is not only beneficial to compensating for the possible slight capacity loss of the battery caused by the lithium consumption of the coating, but also can reduce the risk of weakening the effect of the coating on inhibiting the growth of lithium dendrites due to the excessive amount of the lithium supplement material.

[0111] In some embodiments of the present application, the puncture strength of the separator may be ≥ 350 gf, optionally ≥ 450 gf. Exemplarily, the puncture strength of the separator may be ≥ 350 gf, ≥ 400 gf, ≥ 450 gf, ≥ 500 gf, ≥ 550 gf, ≥ 650 gf, ≥ 700 gf, ≥ 750 gf, ≥ 800 gf, etc. Meeting the given conditions can further reduce the risk of the separator being punctured by dendrites.

[0112] In some embodiments of the present application, the electronic conductivity of the coating at 25 °C may be 10 -6 mS / cm to 10 - 10 mS / cm. This can not only further reduce the negative impact that the coating may have on the impedance of the separator, but also inhibit the transfer of electrons through the separator, reducing the risk of internal short circuit in the battery.

[0113] A second aspect of the present application provides a method for preparing the separator of the first aspect of the present application, which includes: forming a coating on at least one of the two sides of the base film distributed along its thickness direction; and / or forming a coating in the middle of the base film along its thickness direction, the coating including a fluorocarbon material, as well as a solid electrolyte and / or a metal oxide. The separator prepared by this method is beneficial to inhibiting the growth of dendrites and improving the dendrite puncture resistance of the separator.

[0114] In some embodiments of the present application, coating raw materials including fluorocarbon materials, solid electrolytes and / or metal oxides, and binders can be mixed with a solvent to obtain a coating slurry. Exemplarily, according to a preset ratio, fluorocarbon materials such as graphite fluoride powder can be uniformly dispersed in the solvent for primary dispersion, and then a binder is added for secondary dispersion. Optionally, a dispersant can also be added to the primary dispersion, and the dispersion method includes but is not limited to ultrasonic dispersion, where the ultrasonic time can be flexibly selected according to the actual situation. Additionally optionally, a thickener can be added to the secondary dispersion. Further optionally, the primary dispersion and the secondary dispersion can be independently carried out under stirring conditions. For example, the stirring speed during primary dispersion can be 700 revolutions per minute to 1200 revolutions per minute, and the mixing time can be 30 min to 60 min; the stirring speed during secondary dispersion can be 1000 revolutions per minute to 1600 revolutions per minute, and the mixing time can be 30 min to 90 min. In addition, the specific type of the solvent is not particularly limited, and those skilled in the art can flexibly select according to actual needs. For example, it can include but is not limited to one or more of deionized water, N-N dimethylformamide (DMF), N-N methylpyrrolidone (NMP), N-N dimethylacetamide (DMAC), tetrahydrofuran (THF), etc. Optionally, in the coating slurry, the mass percentage of the solvent can be 55% to 75%, and further optionally can be 60% to 70%. Meeting the given conditions is beneficial to making the coating slurry have better viscosity and stability, and further beneficial to obtaining better coating effects and coating uniformity. It should be noted that the selection and relative amounts of the fluorocarbon materials, solid electrolytes, metal oxides, binders, dispersants, and thickeners have been described in detail in the foregoing part and will not be elaborated here.

[0115] In some embodiments of the present application, a coating slurry can be prepared and uniformly coated on a base film, and an isolation film with a coating can be obtained after drying. Optionally, the coating includes but is not limited to blade coating; the drying conditions are not particularly limited, and those skilled in the art can flexibly select according to actual needs. For example, the drying temperature can be 60°C to 80°C, and the drying time can be 5 min to 30 min. The thickness and distribution of the base film and the coating have been described in detail in the foregoing part and will not be elaborated here.

[0116] In some embodiments of the present application, a coating slurry may be coated on at least one of the two sides of the base film distributed along its thickness direction to obtain a coating; alternatively, the base film includes a first base film and a second base film, and a coating slurry may be coated on one of the two sides of the first base film distributed along its thickness direction to form a coating, and the second base film may be stacked on the side of the coating away from the first base film. Wherein, when a coating is formed between the first base film and the second base film, the coating on the first base film may be dried under vacuum conditions and then the second base film may be stacked on the side of the coating away from the first base film for lamination.

[0117] A third aspect of the present application provides a battery, which includes: the separator of the first aspect of the present application, and / or the separator prepared by using the method for preparing a separator of the second aspect of the present application.

[0118] Optionally, the battery may be a secondary battery, that is, a battery that can activate the active material by charging after discharging and can be used continuously.

[0119] Generally, a battery includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte. During the charge and discharge process of the battery, active ions are embedded and extracted back and forth between the positive electrode plate and the negative electrode plate. The separator is disposed between the positive electrode plate and the negative electrode plate to play a role of isolation. The electrolyte plays a role of conducting ions between the positive electrode plate and the negative electrode plate. Among them, the raw material composition and structure of the positive electrode plate, the raw material composition and structure of the negative electrode plate, the material and structural characteristics of the separator, the composition of the electrolyte, etc. can all be conventional selections in the art. The embodiments of the present application do not particularly limit the type of the battery, and it may include but is not limited to lithium batteries, sodium batteries, etc. In the present application, a lithium battery is taken as an example for detailed description:

[0120] [Positive Electrode Plate]

[0121] The positive electrode plate generally includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, and the positive electrode active material layer may include a positive electrode active material. The positive electrode current collector may be a conventional metal foil or a composite current collector (a composite current collector may be formed by disposing a metal material on a polymer substrate). As an example, the positive electrode current collector may include at least one of copper foil, aluminum foil, nickel foil, stainless steel foil, stainless steel mesh, and carbon-coated aluminum foil, and aluminum foil may be selected.

[0122] The positive electrode active material may be a positive electrode active material commonly used in lithium ion batteries, and a compound that can reversibly embed and extract Li + may be used. For example, it may include but is not limited to Li x M′O 2 or Li y M′ 2 O 4(M is a transition metal element, 0 ≤ x ≤ 1, 0 ≤ y ≤ 2) represents a lithium-containing composite oxide, a spinel-like oxide, a layered metal chalcogenide, a positive electrode active material having an olivine structure, etc. Exemplarily, it may include, but is not limited to, LiCoO 2 and other lithium cobalt oxides, LiMn 2 O 4 and other lithium manganese oxides, LiNiO 2 and other lithium nickel oxides, Li 4 / 3 Ti 5 / 3 O 4 and other lithium titanium oxides, lithium manganese nickel composite oxides, lithium manganese nickel cobalt composite oxides, materials having a LiM″PO 4 (M″ includes one or more of Fe, Mn, Ni) and other materials having an olivine-type crystal structure, etc. Optionally, a lithium-containing composite oxide having a layered structure or a spinel-like structure may be used, such as LiCoO 2 , LiMn 2 O 4 , LiNiO 2 , LiNi 1 / 2 Mn 1 / 2 O 2 and other representative lithium manganese nickel composite oxides, LiNi l / 3 Mn 1 / 3 Co 1 / 3 O 2 , LiNi 0.6 Mn 0.2 Co 0.2 O 2 and other representative lithium manganese nickel cobalt composite oxides, or LiNi 1-x-y-z Co x Al y Mg z O 2 (0 ≤ x ≤ 1, 0 ≤ y ≤ 0.1, 0 ≤ z ≤ 0.1, 0 ≤ 1 - x - y - z ≤ 1) and other lithium-containing composite oxides. In addition, the above-mentioned lithium-containing composite oxides may further include, but are not limited to, lithium-containing composite oxides doped with elements such as Ge, Ti, Zr, Mg, Al, Mo, Sn. It can also be understood that the positive electrode active material can be used alone or in combination of multiple types. For example, by simultaneously using a lithium-containing composite oxide having a layered structure and a lithium-containing composite oxide having a spinel structure, both high capacity and stability can be achieved.

[0123] In addition, conductive aids such as carbon black and acetylene black, or binders such as polyvinylidene fluoride and polyethylene oxide may be appropriately added to the positive electrode active material layer. Optionally, other optional aids may also be included. After formulating the positive electrode slurry, it is coated on the positive electrode current collector.

[0124] [Negative electrode plate]

[0125] The negative electrode plate generally includes a negative electrode current collector and a negative electrode active material layer provided on the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material. The negative electrode current collector can be a conventional metal foil or a composite current collector (for example, a composite current collector can be formed by disposing a metal material on a polymer substrate). As an example, the negative electrode current collector can be a copper foil.

[0126] The negative electrode active material can be a negative electrode active material commonly used in lithium-ion batteries, and materials capable of intercalating and deintercalating lithium metal and lithium compounds can be used. For example, it can include, but is not limited to, alloys or oxides such as aluminum, silicon, tin, etc., and various materials such as carbon materials. The oxides can include, but are not limited to, titanium dioxide, etc., and the carbon materials can include, but are not limited to, graphite, pyrolytic carbon, coke, vitreous carbon, fired bodies of organic high-molecular compounds, mesophase carbon microbeads, etc.

[0127] In addition, conductive aids such as carbon black and acetylene black, or binders such as styrene-butadiene rubber, polyvinylidene fluoride, and polyethylene oxide can be appropriately added to the negative electrode active material layer. Optionally, other optional aids can also be included. After being formulated into a positive electrode slurry, it is coated on the negative electrode current collector.

[0128] In some embodiments of the present application, the battery of the third aspect of the present application can also be a lithium metal battery. At this time, the negative electrode active material can include, but is not limited to, metallic lithium. For example, the negative electrode active material can also be an alloy formed by metallic lithium and various other metal or non-metal elements.

[0129] In some embodiments of the present application, the battery of the third aspect of the present application can also be a lithium metal battery without a negative electrode. In this case, the negative electrode can be composed only of a metal foil current collector, and there is no lithium metal on its surface. During the cycling process, only the lithium in the positive electrode is used, and it is deposited and stripped in the form of metallic lithium on the negative electrode side.

[0130] [Electrolyte solution]

[0131] The electrolyte solution can include an electrolyte salt and a solvent.

[0132] In some embodiments of the present application, the solvent can use a non-aqueous solvent (organic solvent) as a non-aqueous electrolyte solution. The non-aqueous solvent can include, but is not limited to, carbonates, ethers, etc.

[0133] The carbonate solvents may include, but are not limited to, cyclic carbonates and chain carbonates. The cyclic carbonates may include, but are not limited to, ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, thioesters (such as ethylene glycol sulfide), etc. The chain carbonates may include, but are not limited to, polar chain carbonates with low viscosity represented by dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and aliphatic branched-chain carbonate compounds. Optionally, the carbonate solvents may be a mixed solvent including cyclic carbonates (especially ethylene carbonate) and chain carbonates.

[0134] The ether solvents may include one or more of, but are not limited to, dimethyl ether tetraethylene glycol (TEGDME), ethylene glycol dimethyl ether (DME), 1,3-dioxolane (DOL), etc.

[0135] In addition to the above non-aqueous solvents, non-aqueous solvents such as chain alkyl esters like methyl propionate, chain triphosphates like trimethyl phosphate, nitrile solvents like 3-methoxypropionitrile, and branched-chain compounds with ether bonds represented by dendritic compounds may also be used.

[0136] In addition, fluorinated solvents may also be used. The fluorinated solvents may include, but are not limited to, H(CF 2 ) 2 OCH 3 、C 4 F 9 OCH 3 、H(CF 2 ) 2 OCH 2 CH 3 、H(CF 2 ) 2 OCH 2 CF 3 、H(CF 2 ) 2 CH 2 O(CF 2 ) 2 H, etc., or may include, but are not limited to, CF 3 CHFCF 2 OCH 3 、CF 3 CHFCF 2 OCH 2 CH 3Straight-chain (perfluoroalkyl) alkyl ethers such as 2-trifluoromethylhexafluoropropyl methyl ether, 2-trifluoromethylhexafluoropropyl ethyl ether, 2-trifluoromethylhexafluoropropyl propyl ether, 3-trifluoromethyloctafluorobutyl methyl ether, 3-trifluoromethyloctafluorobutyl ethyl ether, 3-trifluoromethyloctafluorobutyl propyl ether, 4-trifluoromethyldecafluoropentyl methyl ether, 4-trifluoromethyldecafluoropentyl ethyl ether, 4-trifluoromethyldecafluoropentyl propyl ether, 5-trifluoromethyldodecafluorohexyl methyl ether, 5-trifluoromethyldodecafluorohexyl ethyl ether, 5-trifluoromethyldodecafluorohexyl propyl ether, 6-trifluoromethyltetradecafluoroheptyl methyl ether, 6-trifluoromethyltetradecafluoroheptyl ethyl ether, 6-trifluoromethyltetradecafluoroheptyl propyl ether, 7-trifluoromethylhexadecafluorooctyl methyl ether, 7-trifluoromethylhexadecafluorooctyl ethyl ether, 7-trifluoromethylhexadecafluorooctyl propyl ether, etc. Optionally, the above-mentioned branched (perfluoroalkyl) alkyl ethers and the straight-chain (perfluoroalkyl) alkyl ethers can be mixed and used.

[0137] In some embodiments of the present application, the electrolyte salt may include but is not limited to perchlorates of lithium, lithium organic borates, lithium salts of fluorine-containing compounds, lithium imide salts, etc. Exemplarily, it may include but is not limited to LiClO 4 , LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiC 2 F 4 (SO 3 ) 2 , LiN(C 2 F 5 SO 2 ) 2 , LiC(CF 3 SO 2 ) 3 , LiC n F 2n+1 SO 3 (n≥2), LiN(RfOSO 2 ) 2(wherein, Rf is a fluoroalkyl group), etc. Optionally, the electrolyte salt may include a fluorinated organic lithium salt. Since the fluorinated organic lithium salt has a large anionic property and is easily separated into ions, it is easily soluble in the non-aqueous electrolyte. Further, the concentration of the electrolyte lithium salt in the electrolyte solution may be ≥0.3 mol / L, optionally ≥0.7 mol / L, further optionally ≤1.7 mol / L, and still further optionally ≤1.2 mol / L. Controlling the concentration of the electrolyte lithium salt within the given range can not only obtain good ionic conductivity but also help avoid the problem of electrolyte salt precipitation caused by incomplete dissolution of the electrolyte salt.

[0138] In some embodiments of the present application, the electrolyte solution may further include additives. For example, the additives may include negative electrode film-forming additives, may also include positive electrode film-forming additives, or may further include additives that can improve certain performance of the battery, such as additives that can improve the overcharge performance of the battery, additives that can improve the high-temperature performance of the battery, additives that can improve the low-temperature performance of the battery, etc.

[0139] [Separator membrane]

[0140] The separator membrane adopts the separator membrane of the first aspect of the present application or the separator membrane prepared by the method of the second aspect of the present application. As the base film of the separator membrane, there is no particular limitation in the present application, and any well-known porous structure film with electrochemical stability and mechanical stability can be selected according to actual needs. For example, it may include but is not limited to a single-layer or multi-layer film containing at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0141] The embodiments of the present application do not have particular limitations on the shape of the battery, and it may be cylindrical, square, or any other arbitrary shape. As Figure 4 is a battery 1 with a square structure as an example.

[0142] In some embodiments, the battery may include an outer package. The outer package is used to encapsulate the positive electrode sheet, the negative electrode sheet, and the electrolyte.

[0143] In some embodiments, the outer package may include a housing and a cover plate. Among them, the housing may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose to form a receiving cavity. The housing has an opening communicating with the receiving cavity, and the cover plate can be covered on the opening to close the receiving cavity.

[0144] The positive electrode sheet, the negative electrode sheet, and the separator membrane may form an electrode assembly through a winding process or a stacking process. The electrode assembly is encapsulated in the receiving cavity. The number of electrode assemblies included in the battery may include one or several, which can be adjusted according to requirements.

[0145] In some embodiments, the outer package of the battery may include a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.

[0146] The outer packaging of the battery may also include a soft package, such as a pouch soft package. The material of the soft package may be plastic, such as may include at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0147] In some embodiments, the battery may be a single battery cell, or a battery module or battery pack assembled from single battery cells. The number of batteries included in the battery module or battery pack may be multiple, and the specific number may be adjusted according to the application and capacity of the battery module.

[0148] Figure 5 is a battery module 2 as an example. Refer to Figure 5 , in the battery module 2, a plurality of batteries 1 may be arranged in sequence along the length direction of the battery module 2. Of course, they may also be arranged in any other manner. Further, the plurality of batteries 1 may be fixed by fasteners.

[0149] The battery module 2 may further include a housing having an accommodation space, and a plurality of batteries 1 are accommodated in the accommodation space. In some embodiments, the above battery module may also be assembled into a battery pack, and the number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0150] Figure 6 and Figure 7 is a battery pack 3 as an example. Refer to Figure 6 and Figure 7 , in the battery pack 3, it may include a battery box and a plurality of battery modules 2 disposed in the battery box. The battery box includes an upper box body 4 and a lower box body 5. The upper box body 4 can cover the lower box body 5 and form a closed space for accommodating the battery modules 2. The plurality of battery modules 2 may be arranged in the battery box in any manner.

[0151] The fourth aspect of the present application provides an electrical device, which includes: the battery of the third aspect of the present application.

[0152] Specifically, the battery may serve as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device may include, but is not limited to, mobile devices (such as mobile phones, laptops), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, ships, satellites, and energy storage systems.

[0153] Figure 8The electrical device is taken as an example. The electrical device includes a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. As another example of the electrical device, it may include a mobile phone, a tablet computer, or a laptop computer. The electrical device generally requires being thin and light, and a battery can be used as the power source.

[0154] Hereinafter, embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product instructions. For the reagents or instruments not specified in the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0155] Embodiment 1

[0156] Preparation of the separator membrane:

[0157] 1) Weigh graphite fluoride powder (particle size 500 nm - 1000 nm), Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 Disperse them evenly in N-methylpyrrolidone (NMP), and add hydrolyzed polymaleic anhydride for ultrasonic dispersion. After ultrasonic dispersion for 2 h, a uniform dispersion solution is obtained. Add sodium carboxymethyl cellulose to the dispersion for secondary dispersion, and then add a small amount of polyvinylidene fluoride (PVDF) in sequence for mixing to obtain a coating slurry. Among them, the mass ratio of graphite fluoride powder, hydrolyzed polymaleic anhydride, sodium carboxymethyl cellulose, and PVDF is 1:0.3:0.01:0.01:0.03. Among them, in the coating slurry, the mass percentage of the solvent NMP is 65%.

[0158] 2) Coat the prepared coating slurry on one side of a wet PE-based membrane with a porosity of 50% and a thickness of 9 μm by gravure transfer coating. The coating thickness is 3 μm, and bake it at 60 °C for 5 min to obtain the separator membrane.

[0159] Performance test:

[0160] 1) Puncture strength test of the separator membrane

[0161] Referring to the requirements of GB / T 36363-2018 for polyolefin separators for lithium-ion batteries, lay the separator membrane flat in the fixture and clamp it, and perform puncture at a rate of (100 + 10) mm / min. After completion, take out the specimen, and according to the provisions of GB / T 6672-2001, perform thickness tests at 4 points around the pinhole, take the average value, and calculate the puncture strength.

[0162] 2) Tensile Strength Test of the Separator Membrane (TD (Transverse) & MD (Longitudinal) Directions)

[0163] It is carried out with reference to the requirements of GB / T 36363-2018 for polyolefin separators for lithium-ion batteries.

[0164] 3) Thermal Shrinkage Rate Test of the Separator Membrane (TD & MD Directions)

[0165] It is carried out with reference to the requirements of GB / T 36363-2018 for polyolefin separators for lithium-ion batteries.

[0166] 4) Air Permeability Test of the Separator Membrane

[0167] It is carried out with reference to the standard of GB / T36363-2018.

[0168] Examples 2 to 19 and Comparative Examples 1 to 3

[0169] The differences between Examples 2 to 19 and Comparative Examples 1 to 3 and Example 1 are shown in Table 1 in detail. Among them, in Examples 2 to 19 and Comparative Examples 1 to 3, the total mass of the fluorocarbon material, solid electrolyte and metal oxide in the coating remains unchanged.

[0170] Examples 20 to 24 and Comparative Examples 4 to 5

[0171] The differences between Examples 20 to 24 and Comparative Examples 4 to 5 and Example 1 are shown in Table 2 in detail.

[0172] Relevant tests are carried out on the separator membranes and coin cells of Examples 1 to 24 and Comparative Examples 1 to 5, and the test results are shown in Table 1 and Table 2.

[0173]

[0174]

[0175] Conclusion:

[0176] From Comprehensive Examples 1 to 19 and Comparative Examples 1 to 3 and Table 1, it can be seen that mixing a solid electrolyte and / or a metal oxide with a fluorocarbon material to prepare a separator coating can significantly improve the puncture resistance of the separator. Further, appropriately increasing the thickness of the separator coating or appropriately increasing the content of the solid electrolyte and / or the metal oxide in the coating relative to the fluorocarbon material has a positive promoting effect on enhancing the puncture resistance of the separator. Moreover, disposing the coating on both sides or in the middle of the separator in the thickness direction is beneficial to improving the puncture resistance of the separator. In addition, from Examples 20 to 24 and Comparative Examples 4 to 5, it can be seen that, compared with the case where the coating is not provided, providing the coating can improve the tensile strength and heat shrinkage rate of the separator. The main reason for this analysis is that the coating, as a reinforcing material, can reduce strain and prevent the destruction of the base film structure during the stretching or heat shrinkage process. Additionally, although the air permeability of the separator is affected to a certain extent after the coating is provided, the overall air permeability is still at a good level, and good ion transport characteristics can be exhibited. Further, appropriately increasing the particle size of the fluorocarbon material has a positive promoting effect on improving the air permeability of the separator, and appropriately reducing the particle size of the fluorocarbon material has a promoting effect on improving the tensile strength and heat shrinkage rate of the separator. Making the particle size of the fluorocarbon material within a reasonable range is beneficial to simultaneously taking into account the air permeability, mechanical strength, and heat shrinkage rate of the separator.

[0177] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered within the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. An isolation film, characterized in that, it includes: a base film and a coating, the coating includes a fluorocarbon material, as well as a solid electrolyte and / or a metal oxide, the coating is provided on at least one of the two sides of the base film distributed along its thickness direction, and / or, the coating is provided in the middle of the base film along its thickness direction.

2. The isolation film according to claim 1, characterized in that, the general formula of the fluorocarbon material is CFx, 0.85 ≤ x ≤ 1.5, optionally, 1 ≤ x ≤ 1.

25.

3. The isolation film according to claim 1 or 2, characterized in that, it satisfies at least one of the following conditions: the fluorocarbon material includes at least one of fluorinated graphite, fluorinated carbon black, fluorinated carbon, fluorinated graphene, fluorinated carbon nanotubes, fluorinated carbon fibers; the particle size of the fluorocarbon material is 50 nm to 5 μm, optionally 50 nm to 1 μm; the volume particle size Dv50 of the fluorocarbon material is 50 nm to 1000 nm, optionally 50 nm to 500 nm; the volume particle size Dv90 of the fluorocarbon material ≤ 3 μm, optionally ≤ 1 μm.

4. The isolation film according to any one of claims 1 to 3, characterized in that, The areal density of the coating is 3.5 g / m 2 ~15 g / m 2 ; and / or, the areal density of the fluorocarbon material in the coating is 2 g / m 2 ~14.5 g / m 2 .

5. The isolation film according to any one of claims 1 to 4, characterized in that, based on the mass of the fluorocarbon material, the total mass percentage content of the solid electrolyte and / or the metal oxide ≤ 70%, optionally 20% to 50%.

6. The isolation film according to any one of claims 1 to 5, characterized in that, the wetting angles of the solid electrolyte and the metal oxide are each independently ≤ 15°.

7. The isolation film according to any one of claims 1 to 6, characterized in that, The ionic conductivity of the solid electrolyte at 25 °C is ≥ 10 -4 S / cm; and / or, the lithium intercalation capacity of the metal oxide is ≥ 600 mAh / g.

8. The isolation film according to any one of claims 1 to 7, characterized in that, The solid electrolyte includes at least one of oxide electrolytes, sulfide electrolytes, and phosphate electrolytes. Optionally, it includes Li 7 La 3 Zr 2 O 12 、Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 、Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 、Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 、LiTi 2 (PO 4 ) 3 、Li 3 PS 4 、Li 10 GeP 2 S 12 、Li 6 PS 5 Cl; and / or, the metal oxide includes at least one of oxides of Fe, oxides of Sn, oxides of Ti, oxides of Cu, oxides of Mn, oxides of Al, oxides of Ge, oxides of Zr, oxides of Zn.

9. The isolation film according to any one of claims 1 to 8, characterized in that, the coating further includes: a lithium supplement material.

10. The isolation film according to claim 9, characterized in that, it satisfies at least one of the following conditions: based on the mass of the fluorocarbon material, the mass percentage content of the lithium supplement material ≤ 25%; The lithium supplement material includes LiF, Li 3 N, Li coated with M 2 O, Li x O coated with Si 2 At least one of O, M includes at least one of Fe, Co, Ni, Mn, and the value range of x is 0.5 to 3.

75.

11. The isolation film according to any one of claims 1 to 10, characterized in that, the coating further includes: at least one of a binder, a dispersant, a thickener.

12. The isolation film according to claim 11, characterized in that, based on the mass of the coating, the coating satisfies at least one of the following conditions: the mass percentage content of the binder is 0.5% to 5%, optionally 1% to 3%; the mass percentage content of the dispersant ≤ 2%, optionally 1% to 1.5%; the mass percentage content of the thickener ≤ 2%, optionally 1% to 1.5%.

13. The isolation film according to any one of claims 1 to 12, characterized in that, Meet at least one of the following conditions: The thickness of a single layer of the coating is 1.5 μm to 3.5 μm, optionally 1.5 μm to 3 μm; The total thickness of the coating ≤ 5 μm; The ratio of the total thickness of the coating to the thickness of the base film is 1:(2.5 - 10).

14. The separator film according to any one of claims 1 to 13, characterized in that The coating is provided on at least one of the two sides of the base film distributed along its thickness direction and meets at least one of the following conditions: The two sides of the base film distributed along its thickness direction are respectively close to the positive electrode plate and the negative electrode plate, and the coating is provided on the side of the base film close to the negative electrode plate; and / or, The thickness of the coating provided on the side of the base film close to the negative electrode plate ≥ the thickness of the coating provided on the side of the base film close to the positive electrode plate; The thickness of the base film ≥ 7 μm.

15. The separator film according to any one of claims 1 to 13, characterized in that The coating is provided only in the middle of the base film along its thickness direction and meets at least one of the following two conditions: The thicknesses of the base films on both sides of the coating along its thickness direction are each independently ≤ 9 μm, optionally 5 μm to 9 μm; The coating includes a lithium supplement material, and based on the mass of the fluorocarbon material, the mass percentage content of the lithium supplement material ≤ 10%.

16. The separator film according to any one of claims 1 to 15, characterized in that The puncture strength of the separator film is ≥ 350 gf, optionally ≥ 450 gf; and / or, the electronic conductivity of the coating at 25 °C is 10 -6 mS / cm to 10 -10 mS / cm.

17. A method for preparing the separator film according to any one of claims 1 to 16, characterized in that comprises: Forming a coating on at least one of the two sides of the base film distributed along its thickness direction; and / or, forming the coating in the middle of the base film along its thickness direction, and the coating includes a fluorocarbon material, as well as a solid electrolyte and / or a metal oxide.

18. The method according to claim 17, characterized in that comprises: Mixing coating raw materials including a fluorocarbon material, a solid electrolyte and / or a metal oxide, and an adhesive with a solvent to obtain a coating slurry; Coating the coating slurry on at least one of the two sides of the base film distributed along its thickness direction to obtain the coating; or, the base film includes a first base film and a second base film, coating the coating slurry on one of the two sides of the first base film distributed along its thickness direction to form the coating, and stacking the second base film on the side of the coating away from the first base film.

19. A battery, characterized in that comprises: The separator film according to any one of claims 1 to 16, and / or the separator film prepared by the method according to claim 17 or 18.

20. An electrical device, characterized in that comprises: The battery according to claim 19.

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