Separator, preparation method therefor, battery, and electrical apparatus

Abstract

A separator, a preparation method therefor, a battery, and an electrical apparatus. The separator comprises: a base film and a coating; the coating comprises a fluorine-containing carbon material, and a solid electrolyte and / or a metal oxide; the coating is arranged on at least one side of the two sides of the base film distributed in the thickness direction thereof, and / or the coating is arranged in the middle of the base film in the thickness direction thereof. Thus, dendritic crystal growth can be inhibited, and the dendritic crystal puncture resistance of the separator can be improved, thereby reducing the risks of dendritic crystals puncturing separators and short circuits in batteries.

Description

Isolation film and preparation method thereof, battery and electrical device Technical Field

[0001] The present application belongs to the field of batteries, and specifically relates to an isolation membrane and a preparation method thereof, a battery and an electrical device. Background Art

[0002] Batteries, as energy storage devices, are widely used in various fields. Lithium-ion batteries, for example, are green, environmentally friendly, high-energy, and low-carbon. They are not only used in energy storage power systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric vehicles, and ships, as well as in military equipment and aerospace. With the development of today's society, people's demands for batteries are also becoming increasingly higher.

[0003] Public content

[0004] In view of the technical problems existing in the background technology, the present application provides an isolation membrane, which is intended to inhibit dendrites from piercing the isolation membrane.

[0005] In order to achieve the above objectives, the first aspect of the present application provides an isolation film, which includes:

[0006] A base film and a coating, wherein the coating comprises a fluorocarbon material, a solid electrolyte and / or a metal oxide, and the coating is arranged on at least one of the two sides of the base film along its thickness direction, and / or the coating is arranged in the middle of the base film along its thickness direction.

[0007] The isolation membrane of the present application has the following beneficial effects: it can inhibit dendrite growth and improve the isolation membrane's resistance to dendrite penetration, thereby reducing the risk of dendrites penetrating the isolation membrane and causing short circuits within the battery.

[0008] In some embodiments of the present application, the general formula of the fluorine-containing carbon material is CFx, 0.85≤x≤1.5, optionally, 1≤x≤1.25, which is conducive to further improving the performance of the battery.

[0009] In some embodiments of the present application, the fluorinated carbon material includes one or more of fluorinated graphite, fluorinated carbon black, fluorinated carbon, fluorinated graphene, fluorinated carbon nanotubes, and fluorinated carbon fibers, thereby reducing the risk of dendrites piercing the isolation membrane.

[0010] 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. Meeting the given conditions is beneficial to improving the uniformity and adhesion of the coating, and also helps the isolation membrane to have good ion transmission capability.

[0011] In some embodiments of the present application, the volume particle size Dv50 of the fluorocarbon-containing material is 50 nm to 1000 nm, and can be optionally 50 nm to 500 nm, which is beneficial for further balancing the uniformity of the coating and the ion transmission capacity of the isolation membrane.

[0012] In some embodiments of the present application, the volume particle size Dv90 of the fluorocarbon-containing material is ≤3 μm, and may be ≤1 μm, thereby facilitating a balance between the uniformity of the coating and the ion transmission capability of the isolation membrane.

[0013] In some embodiments of the present application, the surface density of the coating is 3.5 g / m 2 ~15g / m 2 ; and / or, the surface density of the fluorocarbon material in the coating is 2g / m 2 ~14.5g / m 2 .

[0014] In some embodiments of the present application, the total mass percentage of the solid electrolyte and / or the metal oxide is ≤ 70% based on the mass of the fluorocarbon-containing material, and may be 20% to 50%. This helps further reduce the risk of dendrite puncture of the separator while maintaining good ion transmission capacity.

[0015] In some embodiments of the present application, the wetting angles of the solid electrolyte and the metal oxide are independently ≤15°, thereby improving the affinity between the separator and the highly polar electrolyte and the problem that the separator is easily pierced by dendrites.

[0016] 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 capacity of the separator and inhibit the growth of lithium dendrites.

[0017] In some embodiments of the present application, the lithium insertion capacity of the metal oxide is ≥600 mAh / g, which is beneficial for further improving the puncture resistance of the separator and inhibiting the growth of lithium dendrites.

[0018] In some embodiments of the present application, the solid electrolyte includes one or more of an oxide electrolyte, a sulfide electrolyte, and an acid salt electrolyte, and optionally includes Li7La3Zr2O 12 、Li 1.4 Al 0.4 Ti 1.6 (PO4)3、Li 1.5 Al 0.5 Ge 1.5 (PO4)3、Li 1.3 Al 0.3 Ti1.7 (PO4)3, LiTi2(PO4)3, Li3PS4, Li 10 GeP2S 12 , Li6PS5Cl. This is beneficial to further improve the puncture resistance of the isolation membrane and inhibit the growth of lithium dendrites.

[0019] In some embodiments of the present application, the metal oxide includes one or more of Fe oxide, Sn oxide, Ti oxide, Cu oxide, Mn oxide, Al oxide, Ge oxide, Zr oxide, and Zn oxide, thereby effectively suppressing the formation of dendrites.

[0020] In some embodiments of the present application, the coating further comprises a lithium-replenishing material, which is helpful in compensating for the slight capacity loss that may be caused by the consumption of lithium by the coating.

[0021] In some embodiments of the present application, the lithium-supplementing material has a mass percentage of ≤25% based on the mass of the fluorocarbon-containing material. This helps compensate for the slight capacity loss of the battery caused by lithium consumption by the coating, while also helping to avoid the risk of weakening the coating's ability to inhibit lithium dendrite growth due to excessive use of the lithium-supplementing material.

[0022] In some embodiments of the present application, the lithium supplement material includes LiF, Li3N, M-coated Li2O, Li x In one or more Si-coated Li2O, M includes one or more elements selected from Fe, Co, Ni, and Mn, and the value of x ranges from 0.5 to 3.75. This facilitates achieving a better lithium supplementation effect at a lower dosage.

[0023] In some embodiments of the present application, the coating further comprises: one or more of a binder, a dispersant, and a thickener.

[0024] In some embodiments of the present application, based on the mass of the coating, the coating satisfies one or more of the following conditions: (I) the mass percentage of the binder is 0.5% to 5%; (II) the mass percentage of the dispersant is ≤2%; (III) the mass percentage of the thickener is ≤2%.

[0025] In some embodiments of the present application, based on the mass of the coating, the coating satisfies one or more of the following conditions: (i) the mass percentage of the binder is 1% to 3%; (ii) the mass percentage of the dispersant is 1% to 1.5%; (iii) the mass percentage of the thickener is 1% to 1.5%.

[0026] In some embodiments of the present application, the thickness of a single layer of the coating is 1.5 μm to 3.5 μm, and optionally 1.5 μm to 3 μm. This not only improves the separator's resistance to dendrite penetration, but also reduces the risk of increased battery reversible capacity loss and decreased battery energy density caused by excessive coating thickness.

[0027] In some embodiments of the present application, the total thickness of the coating is ≤5 μm, which helps to further reduce the risks of increased loss of battery reversible capacity and decreased battery energy density caused by excessive coating thickness.

[0028] 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:(2.5-10). Meeting the given conditions can take into account both the dendrite penetration resistance of the isolation film and the energy density of the battery.

[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 along its thickness direction, with the two sides of the base film along its thickness direction being adjacent to the positive electrode tab and the negative electrode tab, respectively, and the coating being provided on the side of the base film adjacent to the negative electrode tab. This can effectively inhibit dendrite growth.

[0030] In some embodiments of the present application, the coating is provided only on at least one of the two sides of the base film along its thickness direction, and the thickness of the coating provided on the side of the base film close to the negative electrode tab is greater than the thickness of the coating provided on the side of the base film close to the positive electrode tab. This can effectively inhibit dendrite growth.

[0031] In some embodiments of the present application, the coating is provided only on at least one of the two sides of the base film along the thickness direction thereof, and the thickness of the base film is ≥7 μm.

[0032] 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 thickness of the base film on both sides of the coating along its thickness direction is independently ≤ 9 μm, and can be 5 μm to 9 μm. This helps to improve the puncture resistance of the separator while maintaining the energy density of the battery.

[0033] In some embodiments of the present application, the coating is disposed only in the middle portion of the base film along its thickness. The coating includes a lithium-replenishing material, and the weight percentage of the lithium-replenishing material is ≤ 10% based on the weight of the fluorocarbon-containing material. Meeting these conditions can achieve a balance between the separator's dendrite penetration resistance and the battery's energy density.

[0034] In some embodiments of the present application, the puncture strength of the isolation membrane is ≥350 gf, and optionally ≥450 gf.

[0035] In some embodiments of the present application, the electronic conductivity of the coating at 25°C is 10 -6 mS / cm~10 -10 mS / cm.

[0036] The second aspect of this application provides a method for preparing the separator of the first aspect of this application, comprising: forming a coating on at least one of two sides of a base film along its thickness; and / or forming the coating in the middle of the base film along its thickness, the coating comprising a fluorocarbon material and a solid electrolyte and / or a metal oxide. The separator prepared using this method is advantageous in suppressing dendrite growth and improving the separator's resistance to dendrite penetration.

[0037] In some embodiments of the present application, a coating raw material including a fluorocarbon material, a solid electrolyte and / or a metal oxide, and an adhesive is mixed with a solvent to obtain a coating slurry.

[0038] In some embodiments of the present application, the coating slurry is coated 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, and the coating slurry is coated on one 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.

[0039] The third aspect of the present application provides a battery, which includes: the isolation membrane of the first aspect of the present application, and / or the isolation membrane prepared by the method for preparing the isolation membrane of the second aspect of the present application.

[0040] The fourth aspect of the present application provides an electrical device, which includes: the battery of the third aspect of the present application.

[0041] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0043] FIG1 is a schematic structural diagram of an isolation membrane according to one embodiment of the present application.

[0044] FIG2 is a schematic structural diagram of an isolation membrane according to another embodiment of the present application.

[0045] FIG3 is a schematic structural diagram of an isolation membrane according to another embodiment of the present application.

[0046] FIG4 is a schematic structural diagram of a battery according to an embodiment of the present application.

[0047] FIG5 is a schematic structural diagram of a battery module according to an embodiment of the present application.

[0048] FIG6 is a schematic structural diagram of a battery pack according to an embodiment of the present application.

[0049] FIG7 is an exploded view of a battery pack according to an embodiment of the present application.

[0050] FIG8 is a schematic diagram of an electric device using a battery as a power source according to an embodiment of the present application.

[0051] Explanation of the reference numerals: 11: base film; 11a: side of the base film close to the negative electrode; 11b: side of the base film close to the positive electrode; 111: first sub-base film; 112: second sub-base film; 12: coating; 1: battery; 2: battery module; 3: battery pack; 4: upper case; 5: lower case. DETAILED DESCRIPTION

[0052] The present application will be further described below in conjunction with specific embodiments. It should be understood that these specific embodiments are only used to illustrate the present application and are not used to limit the scope of the present application.

[0053] Below, with appropriate reference to the accompanying drawings, the embodiments of the positive electrode active material and its preparation method, the positive electrode sheet, the battery and the electric device of the present application are described in detail. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the 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 described in the claims.

[0054] The "range" disclosed in this application is defined in the form of a lower limit and / or an upper limit, and 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 boundaries of a particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form an unspecified range, and any lower limit can be combined with other lower limits to form an unspecified range, and similarly any upper limit can be combined with any other upper limit to form an unspecified range. In addition, each separately disclosed point or single value itself can be combined with any other point or single value as a lower limit or upper limit or with other lower limits or upper limits to form an unspecified range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that a range of 60 to 110 and 80 to 120 is 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: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise specified, the numerical range "a-b" is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in this document, and "0-5" is just an abbreviation for these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0055] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0056] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of this application.

[0057] Unless otherwise specified, all steps of the present application can be performed sequentially or randomly, preferably sequentially.

[0058] Unless otherwise specified, the term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Furthermore, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0059] In this application, the terms "plurality" and "multiple" refer to two or more.

[0060] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned description of the drawings and any variations thereof are intended to cover non-exclusive inclusions. Unless otherwise specified, the terms used in this application have the well-known meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the examples of this application).

[0061] With the continuous advancement of the theme of green environmental protection, the application of batteries has penetrated into all aspects of life, including vehicles, electronic equipment, energy storage devices, etc. However, with the continuous promotion of battery applications, people's requirements for batteries are getting higher and higher. Taking lithium batteries as an example, lithium batteries, especially lithium metal batteries, face the problem of lithium dendrite growth at the anode during the cycle, which brings the risk of dendrites piercing the isolation membrane, causing a short circuit and triggering thermal runaway. At present, the isolation membranes that are widely used in related fields usually only serve as physical barriers. As the cycle progresses and the dendrites grow, there is still the possibility of dendrites growing along the pores and piercing through.

[0062] In the present application, a coating is formed by compounding a fluorocarbon material with one or both of a solid electrolyte and a metal oxide, and the coating is formed on at least one side of the two sides of the diaphragm along its thickness direction and / or the middle of the diaphragm. This is not only beneficial for inhibiting dendrite growth, but also for improving the dendrite penetration resistance of the isolation membrane, thereby reducing the risk of dendrites penetrating the isolation membrane and causing a short circuit in the battery.

[0063] The isolation membrane disclosed in the embodiments of the present application is suitable for secondary batteries, and the batteries disclosed in the embodiments of the present application can be used in electrical devices that use batteries as power sources or various energy storage systems that use batteries as energy storage elements. Electrical devices may include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, battery cars, electric cars, ships, spacecraft, and the like. Among them, electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like, and spacecraft may include airplanes, rockets, space shuttles, and spacecraft, and the like.

[0064] The first aspect of the present application provides an isolation membrane, which includes: a base membrane and a coating, the coating including a fluorocarbon-containing material, and a solid electrolyte and / or a metal oxide, the coating being arranged on at least one of the two sides of the base membrane distributed along its thickness direction, and / or the coating being arranged in the middle of the base membrane along its thickness direction.

[0065] In the present application, the fluorocarbon-containing material refers to a carbon-based material having a carbon-fluorine covalent bond, and the solid electrolyte refers to a solid ion conductor electrolyte. With reference to Figures 1 to 3, the isolation membrane includes a base membrane 11 and a coating 12, the coating 12 includes a fluorocarbon-containing material, and a solid electrolyte and / or a metal oxide, and the coating 12 is provided on at least one of the two sides of the base membrane 11 distributed along its thickness direction (for understanding with reference to Figure 1 or Figure 2), and / or, the coating 12 is provided in the middle of the base membrane 11 along its thickness direction (for understanding with reference to Figure 3). Exemplarily, the coating 12 may include a fluorocarbon-containing material and a solid electrolyte, or may include a fluorocarbon-containing material and a metal oxide, or may include a fluorocarbon-containing material, a solid electrolyte and a metal oxide at the same time. Optionally, the metal oxide may include, but is not limited to, a transition metal oxide and / or an oxide of a metal having a plurality of different valence states. Among them, the material composition of the coating can be obtained by combining one or more analyses of 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 spectrometry, etc. The position of the coating can be obtained by characterizing the microstructure of the cross section of the isolation membrane with the help of conventional instruments such as scanning electron microscopes.

[0066] In the present application, the isolation membrane can be used for batteries such as lithium batteries or sodium batteries, wherein a fluorine-containing carbon material is compounded with a solid electrolyte (usually used to prepare a solid electrolyte layer of a solid-state battery) and at least one of a metal oxide and a coating is formed on the base membrane of the isolation membrane, which is beneficial for inhibiting the generation or growth of dendrites, and can also improve the mechanical strength of the isolation membrane and enhance its resistance to dendrite penetration, thereby achieving a better synergistic effect. Taking lithium-ion batteries as an example, fluorocarbon materials have a high lithium insertion capacity and lithium reaction activity, can react with Li to generate C and LiF, and have no intermediate products. They are beneficial to consuming lithium to inhibit the generation of lithium dendrites, and can also react the generated lithium dendrites to inhibit the growth of lithium dendrites (further, forming the coating on the side of the isolation membrane facing the negative electrode is also beneficial to the reaction to generate a LiF interface layer, which helps to form a good and stable SEI and improve the coulombic efficiency, which is more obvious at high rates); in addition, solid electrolytes and metal oxides can also react with lithium or have a certain lithium insertion capacity, and can also consume part of the lithium, thereby inhibiting the generation and growth of lithium dendrites; furthermore, solid electrolytes also have good ion conductivity, which can improve the ion transport capacity of the coating and further inhibit the generation of lithium dendrites; further, the base film of the isolation membrane is usually a polymer. Compared with the base film, the mechanical strength and heat resistance of the solid electrolyte and metal oxide are relatively better, and the oxygen that may exist in the solid electrolyte and metal oxide can also combine with the fluorocarbon material to form a denser coating structure. Furthermore, a better synergistic effect can be exerted to reduce the risk of dendrites piercing the isolation membrane and short circuiting within the battery.

[0067] The isolation membrane of the present application has the following beneficial effects: it can inhibit the growth of dendrites and improve the isolation membrane's resistance to dendrite penetration, thereby reducing the risk of dendrites penetrating the isolation membrane and causing short circuits within the battery.

[0068] Furthermore, the isolation membrane of the first aspect of the present application may optionally meet one or more of the following conditions on the basis of meeting the above conditions.

[0069] In some embodiments of the present application, the general formula of the fluorocarbon material may be CFx, 0.85≤x≤1.5. Optionally, 1≤x≤1.25.

[0070] 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 the like. Optionally, 1≤x≤1.25. Wherein, the value of x in CFx can be obtained by combining the correlation analysis of the fluorine-carbon bond absorption peak area and the carbon-carbon bond absorption peak area in the infrared spectrum. Increasing the fluorine content (atomic percentage) in the fluorine-containing carbon material is conducive to obtaining improved thermal stability. In the present application, the fluorine content in the fluorine-containing carbon material meets the given conditions, which is conducive to making the coating have good thermal stability, insulation and ion conductivity, thereby helping to further improve the performance of the battery.

[0071] In some embodiments of the present application, the fluorinated carbon material may include one or more of fluorinated graphite, fluorinated carbon black, fluorinated carbon, fluorinated graphene, fluorinated carbon nanotubes, and fluorinated carbon fibers. Fluorinated carbon may also include, but is not limited to, fluorinated (nano) carbon fibers, and fluorinated graphite may include, but is not limited to, fluorinated graphite microsheets. Fluorinated carbon materials within the given range have high lithium insertion capacity and lithium reactivity, and can be used in lithium batteries, sodium batteries, and other types of batteries to inhibit dendrite growth and reduce the risk of dendrites piercing the isolation membrane.

[0072] In some embodiments of the present application, the particle size of the fluorocarbon-containing material may be 50 nm to 5 μm. Alternatively, the particle size of the fluorocarbon-containing material may be 50 nm to 1 μm.

[0073] Exemplarily, the particle size of the fluorocarbon-containing material can be 50nm, 100nm, 200nm, 500nm, 800nm, 1μm, 2μm, 3μm, 4μm, 5μm, and the like. The particle size of the fluorocarbon-containing material can be measured using conventional instruments and methods such as a scanning electron microscope and a particle size analyzer. The increase in the particle size of the fluorocarbon-containing material is beneficial for reducing the risk of particles clogging the micropores of the base membrane when forming the coating, thereby reducing the risk of ion transmission channel blockage and the resulting decrease in battery capacity and cycle life due to decreased permeability of the isolation membrane. In addition, the increase in the particle size of the fluorocarbon-containing material will also increase the viscosity of the coating slurry. The use of a fluorocarbon-containing material with a smaller particle size is not only beneficial for obtaining a suitable viscosity for the coating slurry, reducing the risk of decreased coating uniformity and increased coating difficulty due to the high viscosity of the coating slurry, but also helps to improve the adhesion of the fluorocarbon-containing material to the base membrane surface and reduce the risk of powdering that may occur during the coating process. The particle size of the fluorocarbon-containing material falling within the given range is beneficial for coating application, improving coating uniformity and adhesion, and also helps ensure that the separator has good ion transmission capabilities. Optionally, the particle size of the fluorocarbon-containing material can be 50 nm to 1 μm, thereby further balancing the uniformity of the coating and the ion transmission capabilities of the separator. For example, an air permeability of the separator can be achieved of ≤300 s / 100 mL. When the air permeability of the separator is ≤300 s / 100 mL, the separator has good air permeability and good ion transmission properties.

[0074] In some embodiments of the present application, the volume particle size Dv50 of the fluorocarbon-containing material can be 50 nm to 1000 nm. Alternatively, the volume particle size Dv50 of the fluorocarbon-containing material can be 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. This helps to further balance the uniformity and adhesion of the coating, while also allowing the isolation membrane to have good ion transmission capabilities.

[0075] In some embodiments of the present application, the volume particle size Dv90 of the fluorocarbon-containing material may be ≤3 μm. Alternatively, the volume particle size Dv90 of the fluorocarbon-containing material may be ≤1 μm. Exemplarily, the volume particle size Dv90 of the fluorocarbon-containing material may 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. This helps to further balance the uniformity and adhesion of the coating, while also allowing the isolation membrane to have good ion transmission capabilities.

[0076] 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. Alternatively, the particle sizes of the solid electrolyte and the metal oxide can be independently 50 nm to 1 μm, such as 50 nm, 100 nm, 200 nm, 500 nm, 800 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, and so on. This helps to further balance the uniformity of the coating and the ion transport capacity of the isolation membrane.

[0077] In some embodiments of the present application, the surface density of the coating can be 3.5 g / m 2 ~15g / m 2 For example, the surface density of the coating can be 3.5 g / m 2 , 4g / m 2 , 5g / m 2 , 6g / m 2 , 7g / m 2 , 8g / m 2 , 9g / m 2 , 10g / m 2 , 11g / m 2 , 12g / m 2 , 13g / m 2 , 14g / m 2 , 15g / m 2 , etc. The surface density of the coating can be measured by conventional methods. For example, the surface density of the coating can be calculated by testing the weight difference of the isolation membrane before and after coating stripping and the area of ​​the isolation membrane sample. The coating stripping method is not particularly limited and may include but is not limited to mechanical stripping, solvent immersion, etc. Increasing the coating thickness or coating density is beneficial to improving the isolation membrane's resistance to dendrite penetration, while reducing the coating thickness or coating density is beneficial to obtaining better ion transmission characteristics. The surface density of the coating that meets the given range conditions is beneficial to reducing the risk of dendrites piercing the isolation membrane and also helps the isolation membrane to have better ion transmission capabilities.

[0078] In some embodiments of the present application, the surface density of the fluorocarbon-containing material in the coating can be 2 g / m 2 ~14.5g / m 2 For example, the surface density of the fluorocarbon material in the coating can be 2 g / m 2 , 3g / m 2 , 4g / m 2 , 5g / m 2 , 6g / m 2 , 7g / m 2 , 8g / m 2 , 9g / m 2 , 10g / m 2 , 11g / m2 , 12g / m 2 , 13g / m 2 , 14g / m 2 , 14.5g / m 2 , and so on. The surface density of the fluorocarbon-containing material in the coating can be measured by conventional methods. For example, the relationship between the content of the solid electrolyte and / or metal oxide and the fluorocarbon-containing material in the coating can be obtained by combining one or more analyses of conventional methods such as elemental analysis and infrared testing, and calculated in combination with the surface density of the coating. Increasing the content of fluorocarbon-containing material in the coating is beneficial to consuming more lithium by reacting with lithium, thereby improving the inhibitory effect on dendrite growth. Increasing the content of solid electrolyte and / or metal oxide in the coating is beneficial to increasing the strength of the isolation membrane itself and improving the ability to resist dendrite penetration. The surface density of the fluorocarbon-containing material in the coating meets the given conditions, which is beneficial to further inhibiting dendrite growth and reducing the risk of the isolation membrane being penetrated by dendrites.

[0079] In some embodiments of the present application, based on the mass of the fluorocarbon material, the total mass percentage of the solid electrolyte and / or metal oxide may be ≤70%. Alternatively, the total mass percentage of the solid electrolyte and / or metal oxide may be 20% to 50%.

[0080] Exemplarily, the total mass percentage of the solid electrolyte and / or metal oxide can be 70%, 60%, 50%, 40%, 30%, 20%, 10%, and so on. The content relationship of the solid electrolyte and / or metal oxide and the fluorocarbon-containing material can be obtained by combining one or more analyses 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 improve the mechanical strength of the isolation membrane and improve the isolation membrane's own resistance to dendrite penetration. Making the amount of the solid electrolyte and / or metal oxide meet the given range is not only beneficial to improve the dense structure of the coating and improve the isolation membrane's own resistance to dendrite penetration, but also enables the coating to have a better inhibitory effect on dendrite growth, and is also beneficial to the isolation membrane to have better ion transmission capacity. Optionally, the total mass percentage of the solid electrolyte and / or metal oxide can be 20% to 50%, which is beneficial to further reduce the risk of the isolation membrane being pierced by dendrites and to have better ion transmission capacity.

[0081] In some embodiments of the present application, the wetting angles of the solid electrolyte and the metal oxide may be independently ≤15°.

[0082] For example, the wetting angles of the solid electrolyte and the metal oxide can be independently 15°, 12°, 10°, 8°, 5°, etc., or can be independently a range consisting of any of the above values. The wetting angles of the solid electrolyte and the metal oxide can be measured using conventional equipment and conventional methods. For example, a contact angle meter (such as Dataphysics OCA25 video optical contact angle meter, etc.) can be used to drop a liquid phase water droplet on the solid electrolyte or metal oxide sample, and the contact angle value can be obtained by fitting the image profile using software. Fluorocarbon materials are highly hydrophobic and have poor affinity with highly polar electrolytes, making it difficult for the separator to absorb and retain the electrolyte. Metal oxides generally have good hydrophilicity, and the oxygen-containing functional groups on their surfaces can form hydrogen bonds to improve hydrophilicity. Influenced by factors such as polar hydrophilic groups, solid electrolytes generally also exhibit strong hydrophilicity. Introducing solid electrolytes and / or metal oxides into the coating also helps the separator absorb and retain the electrolyte. Fully wetting the interface between the separator and the electrode with the electrolyte can also, to a certain extent, improve the problem of the separator being easily pierced by dendrites. Furthermore, by ensuring that the wetting angles of the solid electrolyte and the metal oxide meet the given conditions, the affinity of the separator with highly polar electrolytes and the problem of the separator being easily pierced by dendrites can be further improved.

[0083] In some embodiments of the present application, the ionic conductivity of the solid electrolyte at 25°C may be ≥10 -4 S / cm.

[0084] For example, the ionic conductivity of the solid electrolyte at 25°C may 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 measured using an AC impedance method. Increasing the ionic conductivity of the solid electrolyte is beneficial for improving the ion transport capacity of the separator. Therefore, satisfying the given conditions can further improve the ion transport capacity of the separator and inhibit the growth of lithium dendrites.

[0085] In some embodiments of the present application, the solid electrolyte may include one or more of an oxide electrolyte, a sulfide electrolyte, and an acid salt electrolyte.

[0086] In the present application, the acid salt electrolyte refers to a solid electrolyte composed of an acid salt material (such as common acid salts such as phosphates and borates), which may include but is not limited to phosphate solid electrolyte materials. For example, taking lithium batteries 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 phosphosulfur sulfide (LGPS), lithium tetrathiophosphate (Li3PS4), lithium phosphorus sulfur chlorosulfide (Li6PS5Cl), etc. One or more of the solid electrolytes in the given range can be combined with fluorocarbon materials to form a dense structure, or can react with lithium to consume lithium, which is beneficial to improving the puncture resistance of the isolation membrane and inhibiting the growth of lithium dendrites. Optionally, the solid electrolyte may include but is not limited to Li7La3Zr2O 12 、Li 1.4 Al 0.4 Ti 1.6 (PO4)3、Li 1.5 Al 0.5 Ge 1.5 (PO4)3、Li 1.3 Al 0.3 Ti 1.7 (PO4)3, LiTi2(PO4)3, Li3PS4, Li 10 GeP2S 12 , Li6PS5Cl, thereby further improving the puncture resistance of the isolation membrane and inhibiting the growth of lithium dendrites.

[0087] In some embodiments of the present application, the lithium insertion capacity of the metal oxide may be ≥600 mAh / g.

[0088] Exemplarily, the lithium insertion capacity of the metal oxide can be ≥600mAh / g, ≥650mAh / g, ≥700mAh / g, ≥750mAh / g, ≥800mAh / g, ≥850mAh / g, ≥900mAh / g, and so on. The lithium insertion capacity of the metal oxide can be expressed by the reversible capacity when it is used as a negative electrode active material. It can be used as an active material for the negative electrode plate and assembled into a battery for charge and discharge tests. A higher lithium insertion capacity can consume more lithium, which is beneficial to further improve the coating's inhibitory effect on dendrite growth. Therefore, meeting the given conditions can not only improve the mechanical strength of the isolation membrane and improve its puncture resistance, but also help to further inhibit the growth of lithium dendrites.

[0089] In some embodiments of the present application, the metal oxide may include one or more of Fe oxide, Sn oxide, Ti oxide, Cu oxide, Mn oxide, Al oxide, Ge oxide, Zr oxide, and Zn oxide. The metal oxides within the given range have a certain lithium insertion capacity or can react with lithium to consume lithium, thereby effectively suppressing the growth of lithium dendrites.

[0090] In some embodiments of the present application, the coating 12 may also include a lithium-replenishing material. For lithium batteries, the coating consumes a small amount of lithium due to lithium insertion or reaction with lithium. Further incorporation of the lithium-replenishing material can help compensate for the slight capacity loss that may be caused by the coating's lithium consumption.

[0091] In some embodiments of the present application, based on the mass of the fluorine-containing carbon material, the mass percentage of the lithium-supplementing material may be ≤25%.

[0092] For example, the mass percentage of the lithium-supplementing material can be 25%, 23%, 20%, 15%, 10%, 5%, and so on. The relative amounts of the lithium-supplementing material and the fluorinated carbon material can be determined by combining conventional methods such as elemental analysis, XRD testing, and infrared testing to determine the specific types and contents of the fluorinated carbon material and the lithium-supplementing material in the coating, and obtained by calculation. For lithium batteries, controlling the content of the lithium-supplementing material within the given range is not only beneficial for compensating for the slight capacity loss of the battery that may be caused by the consumption of lithium by the coating, but also reduces the risk of excessive self-consumption of lithium in the coating due to the excessive use of the lithium-supplementing material, resulting in a decrease in the storage capacity and reaction ability of lithium outside the coating, thereby weakening the coating's effect of inhibiting lithium dendrite growth.

[0093] In some embodiments of the present application, the lithium supplement material may include LiF, Li3N, M-coated Li2O, Li x One or more Si-coated Li2O, M includes one or more of Fe, Co, Ni, and Mn, and the value of x ranges from 0.5 to 3.75.

[0094] For example, the value of x can be 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 3.75, etc. The specific type of lithium supplement material can be determined by combining one or more conventional methods such as elemental analysis, atomic absorption spectrometry, XRD testing, etc. The given lithium supplement material is conducive to achieving a better lithium supplement effect at a lower dosage. In addition, the use of M or Li x Si-coated Li2O can form a passivation layer on the surface of Li2O, which plays a role in slow-release lithium replenishment, and also avoid the capacity attenuation caused by contact with air before Li2O is added.

[0095] In some embodiments of the present application, the coating further comprises: one or more 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 powdering that may exist in the components 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 stratification 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 independently selected from conventional options in the relevant field and can be prepared by conventional methods or obtained commercially. 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 acid block polymer, polyester block polymer, polyethylene glycol type polyol and polyethyleneimine derivative; the thickener can include but is not limited to one or more of sodium hydroxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, polyacrylate, polyurethane, polyether, etc.

[0096] In some embodiments of the present application, the binder content can be 0.5% to 5% by weight based on the weight of the coating. Alternatively, the binder content can be 1% to 3% by weight. For example, it can be 0.5%, 1%, 2%, 3%, 4%, 5%, etc. This can effectively improve the adhesion strength between the coating and the base film.

[0097] In some embodiments of the present application, the mass percentage of the dispersant can be ≤2% based on the mass of the fluorocarbon-containing material. Alternatively, the mass percentage of the dispersant can be 1% to 1.5%. For example, it can be 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 2%, etc. This can effectively improve the uniformity of the coating.

[0098] In some embodiments of the present application, the mass percentage of the thickener may be ≤2% based on the mass of the fluorocarbon-containing material. Alternatively, the mass percentage of the thickener may be 1% to 1.5%. For example, it may be 0.5%, 1%, 2%, 3%, 4%, 5%, etc. This can effectively improve the operability of the coating and the uniformity of the coating.

[0099] In some embodiments of the present application, the thickness of a single-layer coating may be 1.5 μm to 3.5 μm. Alternatively, the thickness of a single-layer coating may be 1.5 μm to 3 μm.

[0100] For example, the thickness of a single-layer coating can be 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, and so on. The coating thickness can be measured using a film thickness meter. Meeting these conditions can not only effectively improve the strength of the separator and inhibit dendrite growth, enhancing the separator's resistance to dendrite penetration, but also achieve better workability. It also reduces the risk of increased reversible capacity loss and decreased battery energy density caused by excessive coating thickness.

[0101] In some embodiments of the present application, the total thickness of the coating may be ≤5 μm. For example, the total thickness of the coating may be 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, and so on. The total thickness of the coating can be obtained by testing the thickness of each single-side coating with a film thickness meter and calculating the sum. Meeting the given conditions is beneficial to further reduce the risk of problems such as increased battery reversible capacity loss and decreased battery energy density due to excessive coating thickness, while enabling the isolation membrane to obtain better resistance to dendrite penetration.

[0102] In some embodiments of the present application, the ratio of the total thickness of the coating layer to the thickness of the base film may be 1:(2.5-10).

[0103] For example, 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, and so on. The thickness of the base film can also be measured using a film thickness meter. Meeting these conditions helps to improve the insulation film's resistance to dendrite penetration while further reducing the risk of increased battery reversible capacity loss and decreased battery energy density caused by excessive coating thickness.

[0104] In some embodiments of the present application, the coating 12 may be provided only on at least one of the two sides of the base film 11 along its thickness direction. The two sides of the base film 11 along its thickness direction are respectively adjacent to the positive electrode tab and the negative electrode tab, and the side 11a of the base film 11 adjacent to the negative electrode tab may be provided with the coating 12. This can be understood by referring to Figure 1. Providing a coating on the side of the base film facing the negative electrode tab can further improve the effect of inhibiting dendrite growth.

[0105] In some embodiments of the present application, the coating 12 may be provided only on at least one of the two sides of the base film 11 distributed along its thickness direction, and the thickness of the coating 12 provided on the side 11a of the base film 11 close to the negative electrode sheet may be ≥ the thickness of the coating 12 provided on the side 11b of the base film 11 close to the positive electrode sheet. Please refer to Figure 2 for understanding. Providing coatings on both sides of the base film along its thickness direction is conducive to further improving the mechanical strength and puncture resistance of the separator, and even if one side of the separator is punctured by dendrites, it is conducive to delaying the time of being completely punctured. Optionally, the thickness of the coating 12 provided on the side 11a of the base film 11 close to the negative electrode sheet may be greater than the thickness of the coating 12 provided on the side 11b of the base film 11 close to the positive electrode sheet, thereby further improving the effect of inhibiting dendrite growth.

[0106] In some embodiments of the present application, the coating 12 may be provided only on at least one of the two sides of the base film 11 along its thickness direction. The thickness of the base film may be ≥ 7 μm. For example, the thickness of the base film may be 7 μm, 8 μm, 10 μm, 12 μm, 15 μm, etc. Meeting these conditions further reduces the risk of dendrite penetration.

[0107] In some embodiments of the present application, the coating layer 12 may be provided only in the middle portion of the base film 11 along its thickness direction, and the thickness of the base film on both sides of the coating layer 12 along its thickness direction may be independently ≤ 9 μm. Alternatively, the thickness of the base film on both sides of the coating layer 12 along its thickness direction may be independently 5 μm to 9 μm.

[0108] With reference to FIG3 , it can be understood that the base film 11 may include a first sub-base film 111 and a second sub-base film 112 arranged along its thickness direction, and the coating 12 may be sandwiched between the first sub-base film 111 and the second sub-base film 112. This arrangement 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 of the solid electrolyte and / or metal oxide with lithium while improving the puncture resistance of the separator. Furthermore, the thickness of the first sub-base film 111 and the second sub-base film 112 can be independently ≤9μm, and optionally can be independently 5μm to 9μm. For example, the thickness of the first sub-base film 111 and the second sub-base film 112 can be independently 9μm, 8μm, 7μm, 6μm, 5μm, 4μm, etc. Meeting the given conditions is beneficial to further take into account the energy density of the battery while reducing the risk of the separator being punctured by dendrites.

[0109] 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, and the coating 12 can include a lithium-supplementing material. Based on the mass of the fluorocarbon material, the mass percentage of the lithium-supplementing material can be ≤10%. For example, the mass percentage of the lithium-supplementing material can be 10%, 8%, 5%, 3%, and so on. With reference to FIG3 , it can be understood that when the coating 12 can be sandwiched between the first sub-base film 111 and the second sub-base film 112, the amount of lithium consumed by the reaction of the solid electrolyte and / or metal oxide with lithium is also less. Controlling the content of the lithium-supplementing material within the given range is not only conducive to compensating for the slight capacity loss of the battery that may be caused by the consumption of lithium by the coating, but also reduces the risk of weakening the inhibitory effect of the coating on lithium dendrite growth due to the excessive use of the lithium-supplementing material.

[0110] In some embodiments of the present application, the puncture strength of the isolation membrane may be ≥350 gf. For example, the puncture strength of the isolation membrane may be ≥350 gf, ≥400 gf, ≥450 gf, ≥500 gf, ≥550 gf, ≥650 gf, ≥700 gf, ≥750 gf, ≥800 gf, and so on. Meeting these conditions can further reduce the risk of dendrite puncture of the isolation membrane. Alternatively, the puncture strength of the isolation membrane may be ≥450 gf.

[0111] In some embodiments of the present application, the electronic conductivity of the coating at 25°C may be 10 -6 mS / cm~10 -10 mS / cm. This not only further reduces the negative impact that the coating may have on the impedance of the separator, but also inhibits the transfer of electrons through the separator, reducing the risk of short circuits within the battery.

[0112] The second aspect of this application provides a method for preparing the separator of the first aspect of this application, comprising: forming a coating on at least one of two sides of a base film along its thickness; and / or forming a coating in the middle of the base film along its thickness, the coating comprising a fluorocarbon material and a solid electrolyte and / or a metal oxide. The separator prepared using this method is advantageous in suppressing dendrite growth and improving the separator's resistance to dendrite penetration.

[0113] In some embodiments of the present application, a coating raw material including a fluorocarbon material, a solid electrolyte and / or a metal oxide, and an adhesive can be mixed with a solvent to obtain a coating slurry. Exemplarily, a fluorocarbon material such as fluorinated graphite powder can be uniformly dispersed in a solvent according to a preset ratio 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, wherein the ultrasonic time can be flexibly selected according to actual conditions. Optionally, a thickener can also be added to the secondary dispersion. Optionally, the primary dispersion and the secondary dispersion can be carried out separately and independently under stirring conditions. For example, the stirring speed during the primary dispersion can be 700 rpm to 1200 rpm, and the mixing time can be 30 min to 60 min; the stirring speed during the secondary dispersion can be 1000 rpm to 1600 rpm, 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 it according to actual needs. For example, it can include but is not limited to one or more of deionized water, N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), N-dimethylacetamide (DMAC), tetrahydrofuran (THF), etc. Optionally, the mass percentage of the solvent in the coating slurry can be 55% to 75%, and optionally 60% to 70%. Meeting the given conditions is conducive to making the coating slurry have good viscosity and stability, and thus is conducive to obtaining good coating effect and coating uniformity. It should be noted that the selection and relative amounts of fluorocarbon materials, solid electrolytes, metal oxides, binders, dispersants and thickeners have been described in detail in the previous section and will not be repeated here.

[0114] In some embodiments of the present application, a coating slurry can be prepared and evenly applied to a base film, followed by drying to produce a coated isolation film. Optionally, the coating includes, but is not limited to, blade coating. Drying conditions are not particularly limited and can be flexibly selected by those skilled in the art based on practical needs. For example, the drying temperature can be 60°C to 80°C, and the drying time can be 5 to 30 minutes. The base film thickness and coating thickness and distribution have been described in detail in the previous section and will not be repeated here.

[0115] In some embodiments of the present application, a coating slurry may be applied to at least one of the two sides of a base film along its thickness direction to form a coating. Alternatively, if the base film includes a first base film and a second base film, a coating slurry may be applied to one of the two sides of the first base film 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. When forming a coating between the first and second base films, the coating on the first base film may be dried under vacuum conditions before the second base film is stacked on the side of the coating away from the first base film for lamination.

[0116] The third aspect of the present application provides a battery, which includes: the isolation membrane of the first aspect of the present application, and / or the isolation membrane prepared by the method for preparing the isolation membrane of the second aspect of the present application.

[0117] Optionally, the battery may be a secondary battery, ie, a battery that can be recharged after being discharged to activate the active material and continue to be used.

[0118] Typically, a battery includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte. During the charge and discharge process of the battery, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet to act as an isolater. The electrolyte acts as an ion conductor between the positive electrode sheet and the negative electrode sheet. Among them, the raw material composition and structure of the positive electrode sheet, the raw material composition and structure of the negative electrode sheet, the material and structural characteristics of the separator, the composition of the electrolyte, etc. can all be conventional choices in this field. The embodiment of the present application has no special restrictions on the type of battery, which may include but is not limited to lithium batteries, sodium batteries, etc. In this application, lithium batteries are used as an example for detailed description:

[0119] [Positive electrode]

[0120] The positive electrode sheet typically includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector. 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 metal material may be disposed on a polymer substrate to form a composite current collector). 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.

[0121] The positive electrode active material can be a positive electrode active material commonly used in lithium-ion batteries, and can be a material that can reversibly embed and deintercalate Li + Compounds, for example, may include but are not limited to Li x M′O2 or Li yLithium-containing composite oxides represented by M'2O4 (M is a transition metal element, 0≤x≤1, 0≤y≤2), spinel-shaped oxides, layered metal chalcogenides, olivine-structured positive electrode active materials, etc. Exemplary materials include but are not limited to lithium cobalt oxides such as LiCoO2, lithium manganese oxides such as LiMn2O4, lithium nickel oxides such as LiNiO2, Li 4 / 3 Ti 5 / 3 O4, lithium titanium oxide, lithium manganese nickel composite oxide, lithium manganese nickel cobalt composite oxide, materials with olivine type crystal structure such as LiM "PO4 (M" includes one or more of Fe, Mn, Ni), etc. Alternatively, a layered structure or spinel structure of lithium-containing composite oxides such as LiCoO2, LiMn2O4, LiNiO2, LiNi 1 / 2 Mn 1 / 2 Lithium manganese nickel composite oxide represented by O2, LiNi l / 3 Mn 1 / 3 Co 1 / 3 O2、LiNi 0.6 Mn 0.2 Co 0.2 Lithium manganese nickel cobalt composite oxide represented by O2, or LiNi 1-x-y-z Co x Al y Mg z O2 (0≤x≤1, 0≤y≤0.1, 0≤z≤0.1, 0≤1-xyz≤1) and other lithium-containing composite oxides. In addition, the above-mentioned lithium-containing composite oxides may also include but are not limited to lithium-containing composite oxides doped with elements such as Ge, Ti, Zr, Mg, Al, Mo, and Sn. It can also be understood that the positive electrode active material can be used alone or in combination. For example, by using a layered lithium-containing composite oxide and a spinel lithium-containing composite oxide at the same time, it is possible to take into account both large capacity and improved stability.

[0122] In addition, conductive additives 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, and other optional additives may be optionally included. After the positive electrode slurry is prepared, it is coated on the positive electrode current collector.

[0123] [Negative electrode]

[0124] The negative electrode sheet typically includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector. 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 metal material disposed on a polymer substrate to form a composite current collector). As an example, the negative electrode current collector can be copper foil.

[0125] The negative electrode active material may be any commonly used negative electrode active material for lithium-ion batteries, and may include compounds capable of intercalating and deintercalating lithium metal or lithium. For example, various materials may include, but are not limited to, alloys or oxides of aluminum, silicon, tin, and the like, and carbon materials. Oxides may include, but are not limited to, titanium dioxide, and carbon materials may include, but are not limited to, graphite, pyrolytic carbon, coke, glassy carbon, sintered organic polymer compounds, and mesocarbon microbeads.

[0126] In addition, conductive additives such as carbon black, acetylene black, or binders such as styrene-butadiene rubber, polyvinylidene fluoride, polyethylene oxide, etc. may be appropriately added to the negative electrode active material layer. Other optional additives may also be included. After preparing the positive electrode slurry, it is coated on the negative electrode current collector.

[0127] In some embodiments of the present application, the battery of the third aspect of the present application may also be a lithium metal battery. In this case, the negative electrode active material may include, but is not limited to, metallic lithium. For example, the negative electrode active material may also be an alloy formed by metallic lithium and various other metal or non-metal elements.

[0128] In some embodiments of the present application, the battery of the third aspect of the present application can also be a negative electrode-free lithium metal battery. In this case, the negative electrode can be composed only of a metal foil current collector without lithium metal on its surface. During the cycle, only the lithium in the positive electrode is used, and it is precipitated and stripped in the form of lithium metal on the negative electrode side.

[0129] [Electrolyte]

[0130] The electrolyte solution may include an electrolyte salt and a solvent.

[0131] In some embodiments of the present application, the solvent may use a non-aqueous solvent (organic solvent) as a non-aqueous electrolyte. The non-aqueous solvent may include but is not limited to carbonates, ethers, and the like.

[0132] Described carbonate solvent can include but not limited to cyclic carbonate and chain carbonate, and cyclic carbonate can include but not limited to ethylene carbonate, propylene carbonate, butylene carbonate, gamma-butyrolactone, thioester (ethylene glycol sulfide etc.) etc. Chain carbonate can include but not limited to the low-viscosity polar chain carbonate, aliphatic branched-chain carbonate compound that dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate etc. are representative. Alternatively, described carbonate solvent can be a mixed solvent comprising cyclic carbonate (particularly ethylene carbonate) and chain carbonate.

[0133] The ether solvent may include, but is not limited to, one or more of tetraethylene glycol dimethyl ether (TEGDME), ethylene glycol dimethyl ether (DME), 1,3-dioxolane (DOL), and the like.

[0134] In addition to the above nonaqueous solvents, nonaqueous solvents that can be used include chain alkyl esters such as methyl propionate, chain triesters such as trimethyl phosphate, nitrile solvents such as 3-methoxypropionitrile, and branched compounds having ether bonds such as dendrimers.

[0135] In addition, fluorine-based solvents can also be used. The fluorine-based solvents may include but are not limited to H(CF2)2OCH3, C4F9OCH3, H(CF2)2OCH2CH3, H(CF2)2OCH2CF3, H(CF2)2CH2O(CF2)2H, etc., or may include but are not limited to CF3CHFCF2OCH3, CF3CHFCF2OCH2CH3 and other linear (perfluoroalkyl) alkyl ethers, i.e., 2-trifluoromethylhexafluoropropyl methyl ether, 2-trifluoromethylhexafluoropropyl ethyl ether, 2-trifluoromethylhexafluoropropyl propyl ether, 3-trifluoromethyloctafluorobutyl methyl ether , 3-trifluoromethyl octafluorobutyl ethyl ether, 3-trifluoromethyl octafluorobutyl propyl ether, 4-trifluoromethyl decafluoropentyl methyl ether, 4-trifluoromethyl decafluoropentyl ethyl ether, 4-trifluoromethyl decafluoropentyl propyl ether, 5-trifluoromethyl dodecafluorohexyl methyl ether, 5-trifluoromethyl dodecafluorohexyl ethyl ether, 5-trifluoromethyl dodecafluorohexyl propyl ether, 6-trifluoromethyl tetradecafluoroheptyl methyl ether, 6-trifluoromethyl tetradecafluoroheptyl ethyl ether, 6-trifluoromethyl tetradecafluoroheptyl propyl ether, 7-trifluoromethyl hexadecafluorooctyl methyl ether, 7-trifluoromethyl hexadecafluorooctyl ethyl ether, 7-trifluoromethyl hexadecafluorooctyl propyl ether, etc. Optionally, the above-mentioned iso(perfluoroalkyl)alkyl ethers and the above-mentioned linear (perfluoroalkyl)alkyl ethers can be mixed.

[0136] In some embodiments of the present application, the electrolyte salt may include but is not limited to lithium perchlorate, organic boron lithium salt, lithium salt of fluorine-containing compound, lithium imide salt, etc., for example, may include but is not limited to LiClO4, LiPF6, LiBF4, LiAsF6, LiSbF6, LiCF3SO3, LiCF3CO2, LiC2F4(SO3)2, LiN(C2F5SO2)2, LiC(CF3SO2)3, LiC n F 2n+1 SO3 (n ≥ 2), LiN (RfOSO2) 2 (wherein Rf is a fluoroalkyl group), etc. Optionally, the electrolyte salt may include a fluorine-containing organic lithium salt, which is easily soluble in a non-aqueous electrolyte due to its large anionicity and easy separation into ions. Furthermore, the concentration of the electrolyte lithium salt in the electrolyte may be ≥ 0.3 mol / L, optionally ≥ 0.7 mol / L, and optionally ≤ 1.7 mol / L, and further optionally ≤ 1.2 mol / L. Controlling the concentration of the electrolyte lithium salt within the given range can not only obtain better ion conductivity, but also help avoid the problem of electrolyte salt precipitation due to failure of the electrolyte salt to completely dissolve.

[0137] In some embodiments of the present application, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, or additives capable of improving certain battery properties, such as but not limited to additives for improving battery overcharge performance, additives for improving battery high-temperature performance, and additives for improving battery low-temperature performance.

[0138] [Isolation film]

[0139] The isolation membrane adopts the isolation membrane of the first aspect of the present application or the isolation membrane prepared by the method of the second aspect of the present application. The base membrane of the isolation membrane is not particularly limited in the present application, and any well-known porous structure membrane with electrochemical stability and mechanical stability can be selected according to actual needs. For example, it can 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.

[0140] The embodiment of the present application has no particular limitation on the shape of the battery, which can be cylindrical, square or any other shape. FIG4 shows a square battery 1 as an example.

[0141] In some embodiments, the battery may include an outer packaging for encapsulating the positive electrode sheet, the negative electrode sheet, and the electrolyte.

[0142] In some embodiments, the outer packaging may include a housing and a cover. The housing may include a bottom plate and side plates connected to the bottom plate, with the bottom plate and side plates enclosing a receiving cavity. The housing may have an opening communicating with the receiving cavity, and the cover may be positioned over the opening to seal the receiving cavity.

[0143] The positive electrode sheet, negative electrode sheet, and separator can be wound or laminated to form an electrode assembly. The electrode assembly is encapsulated in the housing. The number of electrode assemblies in a battery can include one or more, which can be adjusted according to needs.

[0144] In some embodiments, the outer packaging of the battery may include a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.

[0145] The outer packaging of the battery may also include a soft bag, such as a bag-type soft bag. The material of the soft bag may be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0146] In some embodiments, the battery may be either a single battery cell or a battery module or battery pack assembled from battery cells. The battery module or battery pack may contain multiple batteries, and the specific number may be adjusted according to the application and capacity of the battery module.

[0147] Figure 5 shows an example battery module 2. Referring to Figure 5 , within the battery module 2, multiple batteries 1 may be arranged sequentially along the length of the battery module 2. Of course, they may also be arranged in any other manner. Furthermore, the multiple batteries 1 may be secured together using fasteners.

[0148] The battery module 2 may further include a housing having a housing space, wherein the housing space accommodates a plurality of batteries 1. In some embodiments, the battery modules may be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0149] Figures 6 and 7 illustrate an example battery pack 3. Referring to Figures 6 and 7 , the battery pack 3 may include a battery box and multiple battery modules 2 disposed within the battery box. The battery box comprises an upper case 4 and a lower case 5. The upper case 4 can be placed over the lower case 5 to form an enclosed space for accommodating the battery modules 2. The multiple battery modules 2 can be arranged in any manner within the battery box.

[0150] The fourth aspect of the present application provides an electrical device, which includes: the battery of the third aspect of the present application.

[0151] Specifically, the battery can serve as a power source or an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops), electric vehicles (e.g., 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.

[0152] Figure 8 shows an example of an electrical device. This device may include a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. Another example of an electrical device may include a mobile phone, a tablet computer, or a laptop computer. These devices are typically required to be lightweight and thin, and may use batteries as a power source.

[0153] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0154] Example 1

[0155] Preparation of isolation membrane:

[0156] 1) Weigh graphite fluoride powder (particle size 500nm~1000nm), Li 1.3 Al 0.3 Ti 1.7 (PO4)3 is evenly dispersed in N-methylpyrrolidone (NMP), and hydrolyzed polymaleic anhydride is added for ultrasonic dispersion. After ultrasonic dispersion for 2 hours, a uniform dispersed solution is obtained. Sodium hydroxymethyl cellulose is added to the dispersion for secondary dispersion, and then a small amount of polyvinylidene fluoride (PVDF) is added and mixed to obtain a coating slurry. Among them, the mass ratio of fluorinated graphite powder, hydrolyzed polymaleic anhydride, sodium hydroxymethyl cellulose and PVDF is 1:0.3:0.01:0.01:0.03, and the mass percentage of solvent NMP in the coating slurry is 65%.

[0157] 2) The prepared coating slurry was coated on one side of a wet-process PE base film with a porosity of 50% and a thickness of 9 μm by gravure transfer coating. The coating thickness was 3 μm and baked at 60° C. for 5 min to obtain a separator.

[0158] Performance testing:

[0159] 1) Puncture strength test of separator: Referring to the requirements of GB / T 36363-2018 Polyolefin separators for lithium-ion batteries, the separator was flattened in a fixture and clamped. The puncture was performed at a rate of (100+10) mm / min. After completion, the sample was removed and the thickness was tested at 4 points around the pinhole in accordance with the provisions of GB / T 6672-2001. The average value was taken and the puncture strength was calculated.

[0160] 2) Tensile strength test of separator (TD (transverse) & MD (longitudinal) direction): refer to the requirements of GB / T 36363-2018 Polyolefin separators for lithium-ion batteries.

[0161] 3) Thermal shrinkage test of separator (TD & MD directions): refer to the requirements of GB / T 36363-2018 Polyolefin separators for lithium-ion batteries.

[0162] 4) Isolation membrane air permeability test: refer to GB / T36363-2018 standard.

[0163] Examples 2 to 19 and Comparative Examples 1 to 3

[0164] The differences between Examples 2 to 19 and Comparative Examples 1 to 3 and Example 1 are detailed in Table 1. 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.

[0165] Examples 20 to 24 and Comparative Examples 4 to 5

[0166] The differences between Examples 20 to 24 and Comparative Examples 4 to 5 and Example 1 are shown in Table 2.

[0167] Relevant tests were performed on the separators and button batteries of Examples 1 to 24 and Comparative Examples 1 to 5. The test results are shown in Tables 1 and 2.

[0168] in conclusion:

[0169] Based on Examples 1-19, Comparative Examples 1-3, and Table 1, it can be seen that mixing a solid electrolyte and / or metal oxide with a fluorocarbon-containing material to prepare a separator coating can significantly improve the separator's puncture resistance. Furthermore, appropriately increasing the separator coating thickness or appropriately increasing the solid electrolyte and / or metal oxide content relative to the fluorocarbon-containing material in the coating has a positive effect on improving the separator's puncture resistance. Furthermore, applying the coating on both sides or in the middle of the separator along its thickness also helps improve the separator's puncture resistance. In addition, in combination with Examples 20 to 24 and Comparative Examples 4 to 5, it can be seen that compared with not setting the coating, setting the coating can improve the tensile strength and thermal shrinkage of the isolation membrane. The main reason for this is that the coating, as a reinforcing material, can reduce strain and prevent the base membrane structure from being destroyed during stretching or thermal shrinkage. In addition, although the air permeability of the isolation membrane is affected to a certain extent after the coating is set, the overall air permeability is still at a good level, and it can exert good ion transmission characteristics. Furthermore, appropriately increasing the particle size of the fluorocarbon-containing material has a positive promoting effect on improving the air permeability of the isolation membrane, and appropriately reducing the particle size of the fluorocarbon-containing material has a promoting effect on improving the tensile strength and thermal shrinkage of the isolation membrane. Keeping the particle size of the fluorocarbon-containing material within a reasonable range is beneficial to taking into account the air permeability, mechanical strength and thermal shrinkage of the isolation membrane at the same time.

[0170] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments 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. A separation film, wherein: include: A base film and a coating, wherein the coating comprises a fluorine-containing carbon material, and a solid electrolyte and / or a metal oxide, wherein the coating is arranged on at least one of the two sides of the base film along its thickness direction, and / or the coating is arranged in the middle of the base film along its thickness direction.

2. The isolation film according to claim 1, wherein: The general formula of the fluorine-containing carbon material is CFx, 0.85≤x≤1.

5.

3. The isolation film according to claim 1 or 2, wherein: One or more of the following conditions are met: (1) The fluorinated carbon material includes one or more of fluorinated graphite, fluorinated carbon black, fluorinated carbon, fluorinated graphene, fluorinated carbon nanotubes, and fluorinated carbon fibers; (2) The particle size of the fluorine-containing carbon material is 50 nm to 5 μm; (3) The volume particle size Dv50 of the fluorine-containing carbon material is 50 nm to 1000 nm; (4) The volume particle size Dv90 of the fluorine-containing carbon material is ≤3 μm.

4. The separator according to any one of claims 1 to 3, wherein One or more of the following conditions are met: (a) The general formula of the fluorine-containing carbon material is CFx, 1≤x≤1.25; (b) the particle size of the fluorine-containing carbon material is 50 nm to 1 μm; (c) the volume particle size Dv50 of the fluorine-containing carbon material is 50 nm to 500 nm; (d) The volume particle size of the fluorine-containing carbon material is Dv90≤1 μm.

5. The separator according to any one of claims 1 to 4, wherein The surface density of the coating is 3.5 g / m 2 ~15g / m 2 ; and / or, the surface density of the fluorocarbon material in the coating is 2g / m 2 ~14.5g / m 2 .

6. The separator according to any one of claims 1 to 5, wherein Based on the mass of the fluorine-containing carbon material, the total mass percentage of the solid electrolyte and / or the metal oxide is ≤70%.

7. The separator according to any one of claims 1 to 6, wherein The wetting angles of the solid electrolyte and the metal oxide are independently ≤15°.

8. The separator according to any one of claims 1 to 7, wherein The ionic conductivity of the solid electrolyte at 25°C is ≥10 -4 S / cm; and / or, the lithium insertion capacity of the metal oxide is ≥600 mAh / g.

9. The separator according to any one of claims 1 to 8, wherein The solid electrolyte includes one or more of an oxide electrolyte, a sulfide electrolyte, and an acid salt electrolyte; and / or, The metal oxide includes one or more of Fe oxide, Sn oxide, Ti oxide, Cu oxide, Mn oxide, Al oxide, Ge oxide, Zr oxide, and Zn oxide.

10. The separator according to any one of claims 1 to 9, wherein Based on the mass of the fluorine-containing carbon material, the total mass percentage of the solid electrolyte and / or the metal oxide is 20% to 50%; and / or, The solid electrolyte includes Li7La3Zr2O 12 , Li 1.4 Al 0.4 Ti 1.6 (PO4)3、Li 1.5 Al 0.5 Ge 1.5 (PO4)3、Li 1.3 Al 0.3 Ti 1.7 (PO4)3. LiTi2(PO4)3, Li3PS4, Li 10 GeP2S 12 , Li6PS5Cl or more.

11. The separator according to any one of claims 1 to 10, wherein The coating also includes: lithium supplement material.

12. The isolation film according to claim 11, wherein: Based on the mass of the fluorine-containing carbon material, the mass percentage of the lithium supplementing material is ≤25%; and / or, The lithium supplement material includes LiF, Li3N, M-coated Li2O, Li x One or more of Si-coated Li2O, M includes one or more of Fe, Co, Ni, and Mn, and the value range of x is 0.5 to 3.

75.

13. The separator according to any one of claims 1 to 12, wherein: The coating further comprises: one or more of a binder, a dispersant, and a thickener.

14. The isolation film according to claim 13, wherein: Based on the quality of the coating, the coating satisfies one or more of the following conditions: (I) The mass percentage of the binder is 0.5% to 5%; (II) the mass percentage of the dispersant is ≤ 2%; (III) The mass percentage of the thickener is ≤2%.

15. The isolation film according to claim 13 or 14, wherein: Based on the quality of the coating, the coating satisfies one or more of the following conditions: (i) the mass percentage of the binder is 1% to 3%; (ii) the mass percentage of the dispersant is 1% to 1.5%; (iii) The mass percentage of the thickener is 1% to 1.5%.

16. The separator according to any one of claims 1 to 15, wherein One or more of the following conditions are met: (A) The thickness of a single layer of the coating is 1.5 μm to 3.5 μm; (B) the total thickness of the coating is ≤ 5 μm; (C) The ratio of the total thickness of the coating layer to the thickness of the base film is 1:(2.5-10).

17. The separator according to any one of claims 1 to 16, wherein: The coating is disposed only on at least one of the two sides of the base film along the thickness direction thereof and satisfies one or more of the following conditions: (i) The two sides of the base film along the thickness direction are respectively close to the positive electrode sheet and the negative electrode sheet, and the coating is provided on the side of the base film close to the negative electrode sheet; (ii) the thickness of the coating provided on the side of the base film close to the negative electrode plate is greater than or equal to the thickness of the coating provided on the side of the base film close to the positive electrode plate; (iii) The thickness of the base film is ≥7 μm.

18. The separator according to any one of claims 1 to 16, wherein The coating is only provided in the middle of the base film along the thickness direction thereof and satisfies one or both of the following two conditions: (α) the thickness of the base film on both sides of the coating along the thickness direction thereof is independently ≤ 9 μm; (β) The coating layer includes a lithium supplementing material, and the mass percentage of the lithium supplementing material is ≤10% based on the mass of the fluorine-containing carbon material.

19. The isolation film according to claim 18, wherein: The thickness of the base film located on both sides of the coating layer along the thickness direction thereof is independently 5 μm to 9 μm.

20. The separator according to any one of claims 1 to 19, wherein The puncture strength of the isolation film is ≥350 gf; and / or the electronic conductivity of the coating at 25°C is 10 -6 mS / cm~10 -10 mS / cm.

21. The separator according to any one of claims 1 to 20, wherein: The thickness of a single layer of the coating is 1.5 μm to 3 μm; and / or the puncture strength of the isolation film is ≥450 gf.

22. A method for preparing the isolation film according to any one of claims 1 to 21, wherein: include: forming a coating layer on at least one of the two sides of the base film distributed along the thickness direction thereof; And / or, the coating layer is formed in the middle of the base film along the thickness direction thereof, and the coating layer includes a fluorine-containing carbon material, and a solid electrolyte and / or a metal oxide.

23. The method according to claim 22, wherein: include: Mixing coating raw materials including fluorine-containing carbon materials, solid electrolytes and / or metal oxides, and adhesives with a solvent to obtain a coating slurry; The coating slurry is applied 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, the coating slurry is applied on one 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 a side of the coating away from the first base film.

24. A battery, wherein: include: The isolation film according to any one of claims 1 to 21, and / or an isolation film produced by the method according to claim 22 or 23.

25. An electrical device, wherein: include: The battery of claim 24.

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