Composite material and preparation method therefor, separator, electrode sheet, battery, and electric device

Abstract

Disclosed in the present application are a composite material and a preparation method therefor, a separator, an electrode sheet, a battery, and an electric device. The composite material comprises an organic polymer and an inorganic substance, wherein the polymerization monomers of the organic polymer comprise a first monomer and a second monomer. The structural formula of the first monomer comprises: (I), wherein R1 comprises a hydrogen atom or an alkyl having 1-6 carbon atoms; and R2 comprises a hydrogen atom, a substituted or unsubstituted alkyl having 1-21 carbon atoms, a cycloalkyl having 3-6 carbon atoms, an alkylene oxide group having 3-6 carbon atoms, and a substituted or unsubstituted isobornyl, the substituent of the substituted alkyl having 1-15 carbon atoms comprising a hydroxyl. The structural formula of the second monomer comprises: (II), wherein R6, R7, R8 and R9 each independently comprise a hydrogen atom, a substituted or unsubstituted phenyl, a substituted or unsubstituted cycloalkyl, and a linear or branched alkyl or alkenyl. The energy storage modulus of the composite material is 100-1000 MPa.

Description

Composite material and preparation method thereof, isolation film, pole piece, battery and electrical device Technical Field

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

[0002] Secondary batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as in military equipment, aerospace and other fields.

[0003] Currently, the separator adhesive in batteries uses polyvinylidene fluoride. Polyvinylidene fluoride is coated on the separator, wound around the electrode, and then heated and pressed to bond the electrode to the separator, increasing the hardness of the battery cell and maintaining the consistency of the cell thickness. However, after hot pressing, the adhesion between the electrode and the separator is too strong, causing the positive and / or negative electrode sheets to easily release during the battery cycle, thereby reducing the battery's cycling performance.

[0004] Summary of the Invention

[0005] In view of the technical problems existing in the background technology, the present application provides a composite material, which aims to achieve cold pressing bonding between the isolation membrane and the pole piece, thereby improving the cycle performance of the battery.

[0006] In order to achieve the above-mentioned object, the present application provides a composite material in one aspect, wherein the composite material comprises an organic polymer and an inorganic substance, wherein the polymerization monomer of the organic polymer comprises a first monomer and a second monomer, and the structural formula of the first monomer comprises:

[0007] wherein R1 comprises a hydrogen atom or an alkyl group of 1 to 6 carbon atoms, R2 comprises a hydrogen atom, a substituted or unsubstituted alkyl group of 1 to 21 carbon atoms, a cycloalkyl group of 3 to 6 carbon atoms, an epoxyalkyl group of 3 to 6 carbon atoms, or a substituted or unsubstituted isobornyl group, and the substituent in the substituted alkyl group of 1 to 15 carbon atoms comprises a hydroxyl group;

[0008] The structural formula of the second monomer includes:

[0009] Wherein, R6, R7, R8, and R9 independently include a hydrogen atom, a substituted or unsubstituted phenyl group, a substituted or unsubstituted cycloalkyl group, a linear or branched alkyl group, or an alkenyl group, and the storage modulus of the composite material is 100 MPa-1000 MPa.

[0010] The present application includes at least the following beneficial effects: when the composite material of the present application that meets the above-mentioned composition and storage modulus is used for an isolation membrane, after being wound with the positive and negative pole pieces and subjected to a cold pressing process, the composite material can penetrate well into the pores of the pole pieces, so that a strong mechanical linkage occurs between the composite material and the pole pieces, achieving cold pressing bonding between the isolation membrane and the pole pieces, and the bonding force between the pole pieces and the isolation membrane is appropriate, thereby improving the cycle performance of the battery.

[0011] In some embodiments of the present application, the storage modulus of the composite material is 200 MPa-800 MPa, thereby achieving cold-press bonding between the isolation membrane and the pole piece.

[0012] In some embodiments of the present application, the mass ratio of the first monomer to the second monomer is 1:0.55-1, and can be 1:0.6-0.8. Thus, when the composite material is used for an isolation membrane, cold pressing bonding between the isolation membrane and the electrode can be achieved.

[0013] In some embodiments of the present application, the first monomer includes at least one of acrylic acid, methacrylic acid, crotonic acid, heptenoic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, or vinyl acetate. Alternatively, the first monomer includes at least one of methyl methacrylate, lauryl acrylate, or lauryl methacrylate. Thus, the toughness of the composite material during application can be improved, which is more conducive to achieving good bonding.

[0014] In some embodiments of the present application, the second monomer includes at least one of ethylene, styrene, butadiene, or isoprene. This can improve the adhesion and electrolyte resistance of the composite material, thereby helping to improve the safety performance of the battery.

[0015] In some embodiments of the present application, the organic polymer further comprises a third monomer comprising an unsaturated nitrile group. Thus, the use of a third monomer comprising an unsaturated nitrile group can result in the inclusion of a highly polar nitrile group in the composite material, thereby improving the ionic conductivity of the composite material and thereby enhancing the cycling performance of the battery.

[0016] In some embodiments of the present application, the structural formula of the third monomer includes:

[0017] Wherein, R3 includes a hydrogen atom or an alkyl group of 1 to 6 carbon atoms. Thus, a highly polar cyano group can be introduced into the composite material, which helps to improve the ionic conductivity of the composite material and thus improve the cycle performance of the battery.

[0018] In some embodiments of the present application, the third monomer includes at least one of acrylonitrile, methacrylonitrile, or ethacrylonitrile, and may be at least one of acrylonitrile or methacrylonitrile. This helps to improve the ionic conductivity of the composite material, thereby improving the cycle performance of the battery.

[0019] In some embodiments of the present application, the weight ratio of the first monomer, the second monomer, and the third monomer is 1:0.55-1:0.01-0.8, and optionally 1:0.6-0.8:0.05-0.6. This allows the resulting composite material to possess a suitable storage modulus, enabling it to fully utilize its bonding properties under battery operating conditions, thereby improving the battery's cycling performance and safety. Furthermore, when applied to a separator, the composite material helps reduce the separator's electrical resistance and increase its ionic conductivity, thereby improving battery cycling performance.

[0020] In some embodiments of the present application, the polymerized monomer of the organic polymer further includes a fourth monomer, and the fourth monomer includes an unsaturated amide group, thereby improving the electrolyte resistance of the polymer.

[0021] In some embodiments of the present application, the structural formula of the fourth monomer includes:

[0022] Wherein, R4 comprises a hydrogen atom or an alkyl group of 1 to 6 carbon atoms, and R5 comprises a hydrogen atom, an alkyl group of 1 to 6 carbon atoms substituted with a hydroxyl group, or an alkoxy group of 1 to 6 carbon atoms.

[0023] In some embodiments of the present application, the fourth monomer includes at least one of acrylamide, N-methylol acrylamide, or N-butoxymethyl acrylamide, and may be selected from at least one of acrylamide and N-methylol acrylamide. This can improve the electrolyte resistance of the composite material.

[0024] In some embodiments of the present application, the weight ratio of the first monomer, the second monomer, the third monomer, and the fourth monomer is 1:0.55-1:0.01-0.8:0.05-0.7, and optionally 1:0.6-0.8:0.05-0.6:0.1-0.5. This ensures that the storage modulus of the resulting composite material falls within the aforementioned range, enabling cold-press bonding between the separator and the electrode. Furthermore, the separator containing this composite material exhibits lower electrical resistance, increasing its ionic conductivity and improving the battery's cycling performance.

[0025] In some embodiments of the present application, the particle size of the composite material satisfies the following: 2 μm ≤ D50 ≤ 15 μm. Therefore, when used on a separator, the energy density of the battery cell can be increased and the probability of separator clogging can be reduced.

[0026] In some embodiments of the present application, the particle size distribution of the composite material is (D90-D10) / D50, and the particle size distribution of the composite material is less than or equal to 5, and optionally less than 4.5. Thus, when the composite material is used in a separator, the probability of pore blockage can be reduced.

[0027] In some embodiments of the present application, the inorganic material is attached to the surface of the organic polymer and / or dispersed within the organic polymer. Thus, with the organic polymer as the backbone, the inorganic material can be dispersed both within and on the surface of the organic polymer, or distributed solely within the organic polymer, or distributed solely on the surface of the organic polymer. This allows the composite material to fully utilize its bonding properties under battery operating conditions, thereby helping to improve the battery's cycling performance and safety.

[0028] In some embodiments of the present application, the particle size of the inorganic material is 0.0001 μm-2 μm, and optionally the particle size of the inorganic material is 0.005 μm-0.05 μm. This allows the inorganic material and the organic polymer to be fully mixed, thereby improving the ionic conductivity and electrolyte resistance of the separator containing the composite material.

[0029] In some embodiments of the present application, the inorganic substance includes at least one of silicon oxide, aluminum oxide, calcium oxide, zinc oxide, magnesium oxide, sodium sulfate, sodium benzoate, calcium carbonate and modified materials thereof. The inorganic substance may optionally include at least one of silicon dioxide, aluminum oxide, zinc oxide, magnesium oxide or sodium benzoate. More optionally, the inorganic substance includes at least one of fumed silica, silicon powder, aluminum oxide or sodium benzoate.

[0030] In some embodiments of the present application, the inorganic material includes silicon dioxide, and the particle size of the silicon dioxide is 0.0001 μm-2 μm, and optionally 0.005 μm-0.05 μm. Thus, the ionic conductivity and electrolyte resistance of the separator containing the composite material can be improved.

[0031] In some embodiments of the present application, the organic polymer accounts for 50% to 99.9% by weight of the composite material, and optionally 70% to 99% by weight, thereby providing the composite material with good bonding properties, thereby helping to improve the cycle performance and safety performance of the battery.

[0032] In some embodiments of the present application, the outer surface of the composite material is uneven, thereby increasing the contact area between the composite material and the isolation membrane and the electrode, thereby improving the bonding effect.

[0033] A second aspect of the present application provides a method for preparing a composite material, comprising: mixing an organic polymer and an inorganic substance to obtain a composite material, wherein the polymerization monomer of the organic polymer comprises a first monomer and a second monomer, and the structural formula of the first monomer comprises:

[0034] wherein R1 comprises a hydrogen atom or an alkyl group of 1 to 6 carbon atoms, R2 comprises a hydrogen atom, a substituted or unsubstituted alkyl group of 1 to 21 carbon atoms, a cycloalkyl group of 3 to 6 carbon atoms, an epoxyalkyl group of 3 to 6 carbon atoms, or a substituted or unsubstituted isobornyl group, and the substituent in the substituted alkyl group of 1 to 15 carbon atoms comprises a hydroxyl group;

[0035] The structural formula of the second monomer includes:

[0036] Wherein, R6, R7, R8, and R9 each independently comprise a hydrogen atom, a substituted or unsubstituted phenyl group, a substituted or unsubstituted cycloalkyl group, a linear or branched alkyl group, or an alkenyl group. The storage modulus of the composite material is 100 MPa-1000 MPa. Thus, the resulting composite material can be used in an isolation membrane to achieve cold-press bonding between the isolation membrane and the electrode.

[0037] In a third aspect, the present application provides a separator, comprising the composite material or the composite material obtained by the method, thereby improving the cold-pressing adhesion between the separator and the electrode, and improving the cycle performance of the battery.

[0038] In some embodiments of the present application, the ionic conductivity of the isolation membrane is 0.3 mS·cm -1 -0.6mS·cm -1 , optional 0.35mS·cm -1 -0.55mS·cm -1 As a result, its conductive properties can be fully utilized to further improve the cycle performance of the battery.

[0039] In a fourth aspect, the present application provides a pole piece comprising the composite material or the composite material obtained by the method described above, thereby improving the cold-pressing adhesion between the pole piece and the separator and improving the cycle performance of the battery.

[0040] In a fifth aspect, the present application provides a battery comprising the aforementioned separator and / or the aforementioned electrode, thereby having excellent cycle performance and safety performance.

[0041] In a sixth aspect, the present application provides an electrical device comprising the above-mentioned battery, thereby having excellent cycle performance and safety performance.

[0042] 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

[0043] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0044] FIG1 is a schematic diagram of a battery according to one embodiment of the present application.

[0045] FIG. 2 is an exploded view of the battery according to one embodiment of the present application shown in FIG. 1 .

[0046] FIG3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0047] FIG4 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0048] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application.

[0049] FIG6 is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0050] Explanation of reference numerals: 1 battery; 11 housing; 12 electrode assembly; 13 cover plate; 2 battery module; 3 battery pack; 31 upper case; 32 lower case. DETAILED DESCRIPTION

[0051] The following embodiments of the technical solution of the present application are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only used as examples and are not intended to limit the scope of protection of the present application.

[0052] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0053] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0054] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0055] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0056] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

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

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

[0059] Currently, market developments indicate that secondary batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As the application of secondary batteries continues to expand, market demand is also growing.

[0060] The battery cell includes a positive electrode sheet, a negative electrode sheet, and a separator. The battery cell has a certain hardness. That is, because the positive and negative electrode sheets and the separator are bonded together and support each other, a structure with a certain thickness is formed. A structure with a certain thickness has a certain hardness. The negative electrode will expand during the charge and discharge process. If the bonding force is weak, a gap will form between the positive and negative electrode sheets and the separator. The positive and negative electrode sheets and the separator cannot adhere to each other and support each other, causing the battery cell to become loose and the hardness to decrease. For example, in electric vehicles, loose battery cells will cause the battery charging speed to slow down and the battery cycle performance to deteriorate, which will directly shorten the battery life. Electric vehicles need to replace batteries frequently, and consumers' costs for electric vehicles increase.

[0061] A tight fit between the separator and the electrode can improve the battery's discharge capacity, reduce internal resistance, minimize polarization loss, extend the battery's cycle life, and increase the utilization rate of the secondary battery. The adhesive commonly used on existing separators is polyvinylidene fluoride, which requires a hot pressing process (heating during the pressing process after the separator and electrode are stacked) to achieve a tight bond between the separator and the electrode.

[0062] The composite material disclosed in the embodiments of the present application is suitable for 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, for example, 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.

[0063] In a first aspect, the present application provides a composite material, comprising an organic polymer and an inorganic substance, wherein the polymerization monomers of the organic polymer comprise a first monomer and a second monomer, and the structural formula of the first monomer comprises:

[0064] wherein R1 comprises a hydrogen atom or an alkyl group of 1 to 6 carbon atoms, R2 comprises a hydrogen atom, a substituted or unsubstituted alkyl group of 1 to 21 carbon atoms, a cycloalkyl group of 3 to 6 carbon atoms, an epoxyalkyl group of 3 to 6 carbon atoms, or a substituted or unsubstituted isobornyl group, and the substituent in the substituted alkyl group of 1 to 15 carbon atoms comprises a hydroxyl group;

[0065] The structural formula of the second monomer includes:

[0066] Wherein, R6, R7, R8, and R9 independently include a hydrogen atom, a substituted or unsubstituted phenyl group, a substituted or unsubstituted cycloalkyl group, a linear or branched alkyl group, or an alkenyl group, and the storage modulus of the composite material is 100 MPa-1000 MPa.

[0067] In this application, storage modulus refers to the ratio of the energy stored in a material to its strain amplitude under cyclic strain loading. It reflects the elastic recovery ability of a material under strain loading, that is, when a material is subjected to strain loading, it can store a certain amount of elastic energy, and when the strain loading stops, it can release the stored energy and return to its original shape. The storage modulus can be tested using instruments and methods known in the art. For example, a mold can be used to press the composite material into a sample block with a size of 10mm*10mm*4mm, and then the storage modulus of the sample can be tested using Perkin Elmer's DMA 8000, where the test conditions are: single cantilever mode, frequency 1Hz, amplitude 0.5mm, temperature 25°C.

[0068] The composite material of the present application is a combination of organic polymers and inorganic substances, and the polymerization monomers of the organic polymer include the first monomer and the second monomer mentioned above. The inorganic substance can adjust the storage modulus of the composite material, thereby obtaining the composite material with the above storage modulus. When it is used for an isolation membrane, cold pressing bonding between the isolation membrane and the pole piece can be achieved.

[0069] When the storage modulus of the composite material is higher, the composite material's ability to resist deformation is stronger when the separator and the electrode are cold pressed, and the material mainly undergoes elastic deformation, that is, the composite material is relatively hard, resulting in poor infiltration and bonding between the composite material and the separator and the electrode, resulting in poor bonding; and when the storage modulus of the composite material is lower, the material mainly undergoes viscous deformation, that is, the composite material is relatively soft, and it is easy to penetrate into the pores of the separator, causing pore blockage, and also reducing the gap between the separator and the electrode, that is, the bonding between the separator and the electrode is too strong, resulting in easy demolding of the positive electrode and / or negative electrode during the battery cycle.

[0070] The storage modulus of the composite material of the present application is 100MPa-1000MPa. Therefore, when the composite material is used for the isolation membrane, after being wound with the positive and negative pole pieces and subjected to a cold pressing process, the composite material can penetrate well into the pores of the pole pieces, so that a strong mechanical linkage occurs between the composite material and the pole pieces, thereby realizing cold pressing bonding between the isolation membrane and the pole pieces. In addition, the composite material with the storage modulus is not easy to penetrate into the pores of the isolation membrane and cause pore blockage. At the same time, the bonding force between the pole piece and the isolation membrane is appropriate, thereby improving the cycle performance of the battery.

[0071] In some embodiments of the present application, the storage modulus of the composite material is 100 MPa-1000 MPa, for example, 100 MPa-900 MPa, 200 MPa-800 MPa, 300 MPa-700 MPa, 400 MPa-600 MPa, 500 MPa-600 MPa, etc. In other embodiments of the present application, the storage modulus of the composite material is 200 MPa-800 MPa.

[0072] In the structural formula of the above-mentioned first monomer, the alkyl group with 1-6 carbon atoms can be understood as an alkyl group with 1-6 carbon atoms, such as methyl (-CH3), ethyl (-CH2CH3), n-propyl (-CH2CH2CH3), isopropyl (-CH(CH3)2), n-butyl (-CH2CH2CH2CH3), tert-butyl (-C(CH3)3), n-pentyl (-CH2CH2CH2CH2CH3), n-hexyl (-CH2CH2CH2CH2CH2CH3), etc.

[0073] As an example, a substituted or unsubstituted alkyl group of 1-21 carbon atoms, wherein the substituted alkyl group of 1-21 carbon atoms can be understood as a group in which at least one hydrogen atom on an alkyl group with 1-21 carbon atoms is replaced by other groups, such as -CH2OH, -CH2CH2OH, -CH2CH2CH2OH, -CH(CH2OH)2, -CH2CH2CH2CH2OH, -C(CH2OH)3, -CH2CH2CH2CH2CH2OH, etc.; an unsubstituted alkyl group of 1-21 carbon atoms can be understood as an alkyl group with 1-21 carbon atoms, such as methyl (-CH3), ethyl (-CH2CH3), n-propyl (-CH2CH2CH3), isopropyl (-CH(CH3 )2), n-butyl (-CH2CH2CH2CH3), tert-butyl (-C(CH3)3), n-pentyl (-CH2CH2CH2CH2CH3), n-hexyl (-CH2CH2CH2CH2CH2CH3), etc.; cycloalkyl groups of 3-6 carbon atoms, which can be understood as cycloalkyl groups with 3-6 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc.; epoxyalkyl groups of 3-6 carbon atoms, which can be understood as epoxyalkyl groups with 3-6 carbon atoms, such as epoxypropyl, epoxybutyl, epoxypentyl, epoxyhexyl, etc.; substituted isobornyl in substituted or unsubstituted isobornyl groups can be understood as groups after at least one hydrogen atom in the isobornyl group is replaced by other groups, such as methylisobornyl.

[0074] It should be noted that the substituted phenyl group can be understood as a phenyl group in which at least one hydrogen on the phenyl group is replaced by other groups, such as benzyl, phenethyl, etc.; the substituted cycloalkyl group can be understood as a group in which at least one hydrogen on the cycloalkyl group is replaced by other groups, such as cyclopropylmethyl, cyclobutylmethyl, etc.

[0075] In some embodiments of the present application, the weight ratio of the first monomer to the second monomer is 1:0.55-1, for example, 1:0.6-1, 1:0.65-0.95, 1:0.7-0.9, 1:0.75-0.85, 1:0.8-0.85, etc. Thus, by using the first monomer and the second monomer in this mixing ratio to prepare an organic polymer, which, when combined with an inorganic substance, can obtain a composite material with the above-mentioned storage modulus. When the composite material is used in an isolation membrane, after being wound with the positive and negative electrode sheets and subjected to a cold pressing process, the composite material can well penetrate into the pores of the electrode sheet, so that a strong mechanical linkage effect occurs between the composite material and the electrode sheet, achieving cold pressing bonding between the isolation membrane and the electrode sheet, and the bonding force between the electrode sheet and the isolation membrane is appropriate, thereby improving the cycle performance of the battery. In other embodiments of the present application, the weight ratio of the first monomer to the second monomer is 1:0.6-0.8.

[0076] In some embodiments of the present application, the first monomer includes at least one of acrylic acid, methacrylic acid, butenoic acid, heptenoic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate or vinyl acetate. Thus, by using at least one of the above organic substances as the first monomer, the storage modulus of the organic polymer can be adjusted, thereby helping the composite material to exert a good bonding effect. In other embodiments of the present application, the first monomer includes at least one of methyl methacrylate, lauryl acrylate or lauryl methacrylate. In this way, the storage modulus of the organic polymer can be further adjusted to achieve cold pressing bonding between the isolation membrane and the pole piece. In addition, the composite material with the storage modulus is not easy to penetrate into the pores of the isolation membrane and cause pore blockage. At the same time, the bonding force between the pole piece and the isolation membrane is appropriate, thereby improving the cycle performance of the battery.

[0077] In some embodiments of the present application, the second monomer includes at least one of ethylene, styrene, butadiene or isoprene.

[0078] In some embodiments of the present application, the organic polymer further comprises a third monomer comprising an unsaturated nitrile group. This allows the introduction of highly polar cyano groups into the composite material, thereby improving the composite material's ionic conductivity and, consequently, the battery's cycling performance.

[0079] In some embodiments of the present application, the structural formula of the third monomer includes:

[0080] Wherein, R3 includes a hydrogen atom or an alkyl group of 1 to 6 carbon atoms. Thus, a highly polar cyano group can be introduced into the composite material, which helps to improve the ionic conductivity of the composite material and thus improve the cycle performance of the battery.

[0081] In some embodiments of the present application, the third monomer includes at least one of acrylonitrile, methacrylonitrile, or ethacrylonitrile. In other embodiments of the present application, the third monomer includes at least one of acrylonitrile or methacrylonitrile. This helps to improve the ionic conductivity of the composite material, thereby improving the cycling performance of the battery.

[0082] In some embodiments of the present application, the weight ratio of the first monomer, the second monomer and the third monomer is 1:0.55-1:0.01-0.8, for example, 1:0.6-1:0.01-0.8, 1:0.65-0.95:0.01-0.8, 1:0.7-0.9:0.01-0.8, 1:0.75-0.85:0.01-0.8, 1:0.8-0.85:0.01-0.8, 1:0.55-1:0.05-0.8, 1:0.55-1:0.1-0.7, 1:0.55-1:0.2-0.6, 1:0.55-1:0.3-0.5, 1:0.55-1:0.4-0.45, etc. Thus, an organic polymer is prepared using the first monomer, the second monomer, and the third monomer in this mixing ratio, which can be combined with an inorganic substance to obtain the above-mentioned composite material. When the composite material is used in an isolating membrane, after being wound with the positive and negative pole pieces and subjected to a cold pressing process, the composite material can penetrate well into the pores of the pole pieces, so that a strong mechanical linkage occurs between the composite material and the pole pieces, achieving cold pressing bonding between the isolating membrane and the pole pieces, and the bonding force between the pole pieces and the isolating membrane is appropriate, thereby improving the cycle performance of the battery. The resulting composite material has good ionic conductivity, further improving the cycle performance of the battery. In other embodiments of the present application, the weight ratio of the first monomer, the second monomer, and the third monomer is 1:0.6-0.8:0.05-0.6.

[0083] In some embodiments of the present application, the organic polymer may further include a fourth monomer comprising an unsaturated amide group, thereby adjusting the molecular weight of the organic polymer and improving the adhesion of the organic polymer.

[0084] In some embodiments of the present application, the structural formula of the fourth monomer includes:

[0085] Wherein, R4 comprises a hydrogen atom or an alkyl group of 1 to 6 carbon atoms, and R5 comprises a hydrogen atom, an alkyl group of 1 to 6 carbon atoms substituted with a hydroxyl group, or an alkoxy group of 1 to 6 carbon atoms. Thus, the fourth monomer contains an unsaturated amide group, which can adjust the molecular weight of the organic polymer and improve the adhesion of the composite material.

[0086] In some embodiments of the present application, the fourth monomer comprises at least one of acrylamide, N-methylol acrylamide, or N-butoxymethyl acrylamide. Thus, using at least one fourth monomer of the present application can adjust the molecular weight of the organic polymer and improve the adhesion of the composite material. In some embodiments of the present application, the fourth monomer comprises at least one of acrylamide or N-methylol acrylamide.

[0087] In some embodiments of the present application, the weight ratio of the first monomer, the second monomer, the third monomer and the fourth monomer is 1:0.55-1:0.01-0.8:0.05-0.7, for example, 1:0.6-1:0.01-0.8:0.05-0.7, 1:0.65-0.95:0.01-0.8:0.05-0.7, 1:0.7-0.9:0.01-0.8:0.05-0.7, 1:0.75-0.85:0.01-0.8:0.05-0.7, 1:0.55-1:0.05- 0.8: 0.05-0.7, 1: 0.55-1: 0.1-0.7: 0.05-0.7, 1: 0.55-1: 0.2-0.6: 0.05-0.7, 1: 0.55-1: 0.3-0.5: 0.05-0.7, 1: 0.55-1: 0.4-0.45: 0.05-0.7, 1: 0.55-1: 0.01-0.8: 0.1-0.7, 1: 0.55-1: 0.01-0.8: 0.2-0.6, 1: 0.55-1: 0.01-0.8: 0.3-0.5, 1: 0.55-1: 0.01-0.8: 0.4-0.5, etc. Thus, by mixing the first monomer, the second monomer, the third monomer, and the fourth monomer in the above-mentioned proportions, the organic polymer containing them and the inorganic substance can be combined to obtain a composite material with the above-mentioned storage modulus. When the composite material is used in the separator, after being wound with the positive and negative electrode sheets and then subjected to a cold pressing process, the composite material can well penetrate into the pores of the electrode sheet, so that a strong mechanical linkage effect occurs between the composite material and the electrode sheet, achieving cold pressing bonding between the separator and the electrode sheet, and the bonding force between the electrode sheet and the separator is appropriate, thereby improving the cycle performance of the battery. In other embodiments of the present application, the weight ratio of the first monomer, the second monomer, the third monomer, and the fourth monomer is 1:0.6-0.8:0.05-0.6:0.1-0.5.

[0088] In some embodiments of the present application, the particle size of the inorganic material is 0.0001 μm-2 μm, for example, 0.0005 μm-2 μm, 0.001 μm-2 μm, 0.005 μm-2 μm, 0.01 μm-2 μm, 0.05 μm-2 μm, 0.08 μm-2 μm, 0.1 μm-2 μm, 0.2 μm-1.8 μm, 0.5 μm-1.5 μm, 0.7 μm-1.2 μm, 1 μm-1.2 μm, etc. Thus, by using an inorganic material of this particle size, the inorganic material and the organic polymer can be fully mixed to obtain a composite material with the above-mentioned storage modulus, and the ionic conductivity and electrolyte resistance of the separator containing the composite material are improved. In other embodiments of the present application, the particle size of the inorganic material is 0.01 μm-0.05 μm.

[0089] In some embodiments of the present application, the inorganic material is attached to the surface of the organic polymer and / or dispersed within the organic polymer. Thus, with the organic polymer as the backbone, the inorganic material can be dispersed both within and on the surface of the organic polymer, or distributed solely within the organic polymer, or distributed solely on the surface of the organic polymer. This allows the composite material to fully utilize its bonding properties under battery operating conditions, thereby helping to improve the battery's cycling performance and safety.

[0090] In some embodiments of the present application, the inorganic substance includes at least one of silicon oxide, aluminum oxide, calcium oxide, zinc oxide, magnesium oxide, sodium sulfate, sodium benzoate, calcium carbonate, and modified materials thereof. Thus, the composite material obtained by compounding at least one of the above-mentioned inorganic substances with an organic polymer has good bonding properties, thereby improving the cycle performance and safety performance of the battery. In other embodiments of the present application, the inorganic substance includes at least one of silicon dioxide, aluminum oxide, zinc oxide, magnesium oxide, or sodium benzoate. Furthermore, the inorganic substance includes at least one of fumed silica, silicon powder, aluminum oxide, or sodium benzoate.

[0091] In some embodiments of the present application, the inorganic material includes silicon dioxide, and the particle size of the silicon dioxide is 0.0001 μm-2 μm, for example, 0.0005 μm-2 μm, 0.001 μm-2 μm, 0.005 μm-2 μm, 0.01 μm-2 μm, 0.05 μm-2 μm, 0.08 μm-2 μm, 0.1 μm-2 μm, 0.2 μm-1.8 μm, 0.5 μm-1.5 μm, 0.7 μm-1.2 μm, 1 μm-1.2 μm, etc. Therefore, by using silicon dioxide in this particle size range as an inorganic material and compounding it with the above-mentioned organic polymer to obtain a composite material, and using this composite material in an isolation membrane, pore blocking will not occur, and the ionic conductivity and electrolyte resistance of the isolation membrane containing the composite material can be improved. In other embodiments of the present application, the particle size of the silicon dioxide is 0.005 μm-0.05 μm.

[0092] In some embodiments of the present application, based on the mass of the composite material, the mass proportion of the organic polymer is 50%-99.9%, for example, 55%-99%, 60%-95%, 65%-90%, 70%-85%, 75%-80%, etc. Therefore, when the composite material is used for the separator, after being wound with the positive and negative pole pieces and subjected to a cold pressing process, the composite material can penetrate well into the pores of the pole piece, so that a strong mechanical linkage effect occurs between the composite material and the pole piece, achieving cold pressing bonding between the separator and the pole piece, and the bonding force between the pole piece and the separator is appropriate, thereby improving the cycle performance of the battery. In other embodiments of the present application, based on the mass of the composite material, the mass proportion of the organic polymer is 70%-99%.

[0093] In some embodiments of the present application, the particle size of the composite material satisfies the following conditions: 2 μm ≤ D50 ≤ 15 μm, for example, 3 μm ≤ D50 ≤ 14 μm, 5 μm ≤ D50 ≤ 12 μm, 8 μm ≤ D50 ≤ 10 μm, etc. Therefore, when a composite material with this particle size is used in a separator, the energy density of the battery cell can be increased while reducing the probability of separator pore blockage.

[0094] It should be noted that, in the examples of the present application, the D50 of the composite material is the particle size corresponding to when the cumulative particle size volume distribution percentage reaches 50%, and the test method is:

[0095] Reference standard GB / T 19077-2016 / ISO 13320:2009 particle size distribution laser diffraction method. Use a laser particle size analyzer (Malvern 3000, MasterSizer 3000) for testing, and use a helium-neon red light source as the main light source. Take a clean small beaker and add 1g of the sample to be tested, add a drop of surfactant, add 20ml of deionized water (the sample concentration ensures that the light shielding is 8-12%), and ultrasonicate at 53KHz / 120W for 5 minutes to ensure that the sample is completely dispersed. Turn on the laser particle size analyzer, clean the optical path system, and automatically test the background. Stir the ultrasonicated test solution to make it evenly dispersed, place it in the sample cell as required, and start measuring the particle size. The measurement results can be read from the instrument.

[0096] In some embodiments of the present application, the particle size distribution of the composite material is (D90 - D10) / D50, and the particle size distribution of the composite material is less than or equal to 5. This results in a relatively uniform particle size of the composite material, which can reduce the probability of pore blockage when used in a separator. In other embodiments of the present application, the particle size distribution of the composite material is less than 4.5.

[0097] It should be noted that the test method for D50 is as described above. In the embodiments of the present application, D90 refers to the particle size corresponding to when the cumulative particle size volume distribution percentage of the particles reaches 90%, and D10 refers to the particle size corresponding to when the cumulative particle size volume distribution percentage of the particles reaches 10%. The test method is the same as the test method for D50.

[0098] In some embodiments of the present application, the outer surface of the composite material is uneven, thereby increasing the contact area between the composite material and the isolation membrane and other components, thereby improving the bonding effect.

[0099] A second aspect of the present application provides a method for preparing a composite material, comprising: mixing an organic polymer and an inorganic substance to obtain a composite material, wherein the polymerization monomer of the organic polymer comprises a first monomer and a second monomer, and the structural formula of the first monomer comprises:

[0100] wherein R1 comprises a hydrogen atom or an alkyl group of 1 to 6 carbon atoms, R2 comprises a hydrogen atom, a substituted or unsubstituted alkyl group of 1 to 21 carbon atoms, a cycloalkyl group of 3 to 6 carbon atoms, an epoxyalkyl group of 3 to 6 carbon atoms, or a substituted or unsubstituted isobornyl group, and the substituent in the substituted alkyl group of 1 to 15 carbon atoms comprises a hydroxyl group;

[0101] The structural formula of the second monomer includes:

[0102] Wherein, R6, R7, R8, and R9 each independently comprise a hydrogen atom, a substituted or unsubstituted phenyl group, a substituted or unsubstituted cycloalkyl group, a linear or branched alkyl group, or an alkenyl group. The storage modulus of the composite material is 100 MPa-1000 MPa. Thus, the resulting composite material can be used in an isolation membrane to achieve cold-press bonding between the isolation membrane and the electrode.

[0103] In some embodiments of the present application, the method for preparing a composite material includes:

[0104] Mixing water, an emulsifier, an initiator, a first monomer and a second monomer, and heating the mixture for reaction to obtain an organic polymer emulsion;

[0105] The organic polymer emulsion and the inorganic substance are mixed to obtain a composite material.

[0106] The organic polymer can be prepared by emulsion polymerization of a first monomer, a second monomer, and optionally a third monomer and an optional fourth monomer.

[0107] The present application obtains an organic polymer emulsion by emulsion polymerization, and then mixes the organic polymer emulsion with an inorganic substance and obtains a composite material by spray drying.

[0108] Emulsion polymerization is a process in which monomers are dispersed in water with the help of emulsifiers and mechanical stirring to form an emulsion, and then an initiator is added to initiate monomer polymerization.

[0109] Emulsifiers are substances that can transform mutually incompatible oils and water into an emulsion that is difficult to separate. Emulsifiers are typically surfactants that have both hydrophilic polar groups and hydrophobic (lipophilic) non-polar groups. For example, emulsifiers include at least one of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, sodium dodecylbenzene sulfate, sodium laurate, sodium stearate, or sodium palmitoleate.

[0110] An initiator is a substance that can initiate polymerization of monomers. For example, a free radical initiator refers to a class of compounds that readily decompose into free radicals (i.e., primary free radicals) upon heating and can be used to initiate free radical polymerization and copolymerization of olefinic and dienic monomers. For example, initiators include at least one of potassium persulfate, ammonium persulfate, azobisisobutyronitrile, dimethyl azobisisobutyrate, benzoyl peroxide, or dioctanoyl peroxide.

[0111] Water, emulsifier, initiator, and monomers constituting organic polymers are blended and stirred. Water and emulsifier are stirred and dispersed to form an emulsion, that is, the emulsifier forms micelles in the aqueous phase, and monomers are solubilized in most of the micelles. Under heating conditions, the initiator initiates polymerization of the monomers inside the micelles to obtain an emulsion.

[0112] Spray drying, through mechanical action, disperses the material to be dried (a mixture of organic polymer emulsion and inorganic matter) into very fine mist-like particles (increasing the water evaporation area and accelerating the drying process). When in contact with hot air, most of the water is removed instantly, and the solid matter in the material is dried into powder.

[0113] The third aspect of the present application provides a separator, comprising the composite material of the first aspect of the present application or a composite material obtained by the method of the second aspect. Thus, when the composite material described above is applied to the separator, after being wound with the positive and negative electrode sheets and then cold-pressed, the composite material can effectively penetrate the pores of the electrode sheets, resulting in a strong mechanical interlocking effect between the composite material and the electrode sheets, achieving cold-pressed bonding between the separator and the electrode sheets. Furthermore, the composite material with a storage modulus is not likely to penetrate the pores of the separator and cause pore blockage. At the same time, the bonding force between the electrode sheets and the separator is appropriate, thereby improving the cycle performance of the battery.

[0114] In some embodiments of the present application, the ionic conductivity of the isolation membrane is 0.3 mS·cm -1 -0.6mS·cm -1 , for example 0.35mS·cm -1 -0.55mS·cm -1, 0.4mS·cm -1 -0.5mS·cm -1 , 0.45mS·cm -1 -0.5mS·cm -1 Conductivity is the ability of the separator to conduct current, and is expressed in Siemens per meter (S / m). The ionic conductivity of the separator of the present application is within the above range, which can give full play to its conductive and adhesive properties, further improving the cycle performance of the secondary battery. In other embodiments of the present application, the ionic conductivity of the separator is 0.35mS·cm -1 -0.55mS·cm -1 .

[0115] It should be noted that the ionic conductivity test method of the composite material described in this application is as follows: the isolation membrane is cut into 40mm x 20mm test pieces, and the cut isolation membranes are stacked in groups of 4 layers. A commercial electrolyte is used (at 25°C, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain a mixed solvent, and then LiPF6 is dissolved in the above mixed solvent to obtain an electrolyte, wherein the concentration of LiPF6 is 1 mol / L) to completely wet the isolation membrane, and then assembled into a symmetrical battery for testing in a glove box. The impedance of the isolation membrane is tested using an electrochemical workstation with a measurement range of 1Hz to 100,000Hz, and the applied AC signal polarization is 5mV. The ionic conductivity can be calculated from the test results of the AC impedance, and the formula is as follows: δ = 1000L / RA

[0116] Where δ represents the ionic conductivity, unit: mS / cm; A represents the area of ​​the single-layer isolation membrane, unit: cm 2 , L represents the thickness of the test isolation film, the unit is cm; R represents the resistance of the test isolation film, the unit is Ω.

[0117] In some embodiments of the present application, the isolation film of the present application includes a base film and an adhesive layer, wherein the adhesive layer is formed on at least one side of the base film, and the adhesive layer includes the composite material of the first aspect of the present application or the composite material obtained by the method described in the second aspect. For example, the adhesive layer is formed on both opposite sides of the base film.

[0118] In the present application, there is no particular limitation on the type of base membrane, and any known base membrane with a porous structure having good chemical stability and mechanical stability can be selected.

[0119] In some embodiments of the present application, the base film may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, or polyvinylidene fluoride. The base film may be a single-layer film or a multi-layer composite film, without particular limitation. When the base film is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0120] The isolation membrane described herein can be prepared using conventional methods in the art. For example, the composite material described in the first aspect of the present invention can be dissolved in an organic solvent to obtain a slurry, which can then be coated on a base film and then dried to remove the organic solvent, thereby obtaining the isolation membrane described herein.

[0121] In some embodiments of the present application, the coating density of the composite material on one side of the base film is 0.3 g / m 2 -1.0g / m 2 , for example 0.4g / m 2 -0.9g / m 2 , 0.5g / m 2 -0.8g / m 2 , 0.6g / m 2 -0.7g / m 2 In this way, the bonding force between the separator and the electrode can be improved, and the dynamic performance and safety performance of the battery can be improved. In other embodiments of the present application, the coating density of the composite material on one side of the base film can be 0.3g / m 2 -0.8g / m 2 .

[0122] It should be noted that the coating density on one side refers to the coating amount on one side. The test method for the coating density of the composite material on one side of the base film includes: taking a certain area of ​​the isolation film and obtaining the isolation film area S in m 2 , weigh the weight M1 of the isolation film (having an adhesive layer including a composite material) in g, weigh the mass M2 of the isolation film without the adhesive layer of the same area S in g, and the coating density of the composite material on one side of the base film is calculated as (M1-M2) / S.

[0123] In a fourth aspect, the present application provides a pole piece, comprising the composite material of the first aspect or the composite material obtained by the method of the second aspect, thereby improving the stability of the pole piece and the cycle performance and safety performance of the battery.

[0124] It should be noted that the electrode described in this application can be a positive electrode or a negative electrode.

[0125] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer includes the composite material of the first aspect of the present application. Specifically, the composite material can be used as a binder in the positive electrode active material layer.

[0126] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0127] In some embodiments of the present application, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0128] In some embodiments of the present application, the positive electrode active material may be a positive electrode active material for batteries known in the art.

[0129] As an example, when the positive electrode plate is used in a lithium-ion battery, the positive electrode active material may adopt a positive electrode active material for lithium-ion batteries that is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al 0.05 O2) or at least one of its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, or a composite material of lithium iron manganese phosphate and carbon.

[0130] For example, when the positive electrode plate is used in a sodium ion battery, the positive electrode active material may be a positive electrode active material known in the art for use in sodium ion batteries. For example, the positive electrode active material may include, but is not limited to, at least one of a layered transition metal oxide, a polyanion compound, and a Prussian blue analog.

[0131] Examples of the layered transition metal oxides include:

[0132] Na 1-x Cu h Fe k Mn l M 1 m O 2-y , where M 1 Including at least one of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn or Ba, 0 <x≤0.33,0<h≤0.24,0≤k≤0.32,0<l≤0.68,0≤m<0.1,h+k+l+m=1,0≤y<0.2;

[0133] Na 0.67 Mn 0.7 Ni z M 2 0.3-z O2, where M 2 including at least one of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn or Ba, 0 <z≤0.1;

[0134] Na a Li bNi c Mn d Fe e O2, where 0.67 < a ≤ 1, 0 < b < 0.2, 0 < c < 0.3, 0.67 < d + e < 0.8, and b + c + d + e = 1.

[0135] As an example of the above polyanion compound, for example, the following can be listed:

[0136] A 1 f M 3 g (PO4) i O j X 1 3-j , where A 1 includes at least one of H, Li, Na, K, or NH4, M 3 includes at least one of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, or Zn, X 1 is at least one of F, Cl, or Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, 0 ≤ j ≤ 2;

[0137] Na n M 4 PO4X 2 , where M 4 includes at least one of Mn, Fe, Co, Ni, Cu, or Zn, X 2 is at least one of F, Cl, or Br, 0 < n ≤ 2;

[0138] Na p M 5 q (SO4)3, where M 5 includes at least one of Mn, Fe, Co, Ni, Cu, or Zn, 0 < p ≤ 2, 0 < q ≤ 2;

[0139] Na s Mn t Fe 3-t (PO4)2(P2O7), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example, t is 0, 1, 1.5, 2, or 3.

[0140] As an example of the above Prussian blue analog, for example, the following can be listed:

[0141] A u M 6 v [M 7 (CN)6] w ·xH2O, where A includes H + 、NH4+ At least one of an alkali metal cation or an alkaline earth metal cation, M 6 and M 7 Each independently includes at least one of transition metal cations, 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, 0 < x < 6. For example, A includes H + 、Li + 、Na + 、K + 、NH4 + 、Rb + 、Cs + 、Fr + 、Be 2+ 、Mg 2+ 、Ca 2+ 、Sr 2+ 、Ba 2+ or Ra 2+ At least one of, M 6 and M 7 Each independently includes at least a cation of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn or W.

[0142] In some embodiments of the present application, the positive electrode active material layer may further optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene or carbon nanofibers. <00-00424>In some embodiments, the positive electrode active material layer may further optionally include other binders. As an example, the other binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer or tetrafluoroethylene-hexafluoropropylene copolymer and fluorinated acrylate resin.

[0144] In some embodiments, the positive electrode sheet can be prepared by the following method: dispersing the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the composite material and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode sheet can be obtained.

[0145] In some embodiments of the present application, based on the total mass of the positive electrode active material layer, the mass ratio of the composite material in the positive electrode sheet is 1% - 3%, such as 1.2% - 2.8%, 1.5% - 2.5%, 1.8% - 2.2%, 2% - 2.2%, etc. Thus, the score loss of the positive electrode sheet can be reduced, thereby improving the cycle performance of the battery containing it.​

[0146] Similarly, the electrode sheet described herein may also be a negative electrode sheet. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector. The negative electrode active material layer includes the composite material described in the first aspect of this application. Specifically, the composite material may be used as a binder in the negative electrode active material layer.

[0147] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0148] In some embodiments of the present application, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0149] In some embodiments of the present application, the negative electrode active material may be a negative electrode active material for a battery that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, or silicon alloys. The tin-based material may include at least one of elemental tin, tin oxides, or tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0150] In some embodiments of the present application, the negative electrode active material layer may further include a conductive agent, which may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0151] In some embodiments of the present application, the negative electrode active material layer may optionally further include other binders, and the other binders may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

[0152] In some embodiments of the present application, the negative electrode active material layer may optionally further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0153] In some embodiments of the present application, the negative electrode sheet can be prepared by the following method: the above-mentioned components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the composite material and any of the above-mentioned optional components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0154] In some embodiments of the present application, based on the total mass of the negative electrode active material layer, the composite material accounts for 1% to 3% by mass in the negative electrode sheet, for example, 1.2% to 2.8%, 1.5% to 2.5%, 1.8% to 2.2%, 2% to 2.2%, etc. This can reduce the shedding of the negative electrode sheet, thereby improving the cycle performance of the battery containing the composite material.

[0155] In a fifth aspect, the present application provides a battery comprising the separator according to the third aspect and / or the electrode according to the fourth aspect, thereby providing the battery with excellent cycle performance and safety performance.

[0156] Typically, a battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0157] The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or solid.

[0158] In some embodiments of the present application, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0159] In some embodiments of the present application, when the battery is a lithium ion battery, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, or lithium tetrafluorooxalatophosphate.

[0160] In some embodiments of the present application, when the battery is a sodium ion battery, the electrolyte sodium salt may include at least one of sodium hexafluorophosphate, sodium difluorooxalatoborate, sodium tetrafluoroborate, sodium bisoxalatoborate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium trifluoromethylsulfonate or sodium bis(trifluoromethylsulfonyl)imide.

[0161] In some embodiments of the present application, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone or diethyl sulfone.

[0162] In some embodiments of the present application, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0163] The battery of the present application includes a battery cell form, a battery module form and a battery pack form.

[0164] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0165] In some embodiments, the battery cell may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0166] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the battery cell may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0167] The present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square, or any other shape. For example, FIG1 shows a battery cell 1 having a square structure as an example.

[0168] In some embodiments, referring to Figure 2, the outer packaging may include a shell 11 and a cover plate 13. The shell 11 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 11 has an opening connected to the receiving cavity, and the cover plate 13 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 12 through a winding process or a lamination process. The electrode assembly 12 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 12. The number of electrode assemblies 12 contained in the battery cell 1 can be one or more, and those skilled in the art can select according to specific actual needs.

[0169] In some embodiments, battery cells may be assembled into a battery module. The battery module may contain one or more battery cells. The specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0170] Figure 3 shows an example battery module 2. Referring to Figure 3 , within the battery module 2, multiple battery cells 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 battery cells 1 may be secured together using fasteners.

[0171] Optionally, the battery module 2 may further include a housing having an accommodation space, and the plurality of battery cells 1 are accommodated in the accommodation space.

[0172] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0173] Figures 4 and 5 illustrate an example battery pack 3. Referring to Figures 4 and 5 , a battery pack 1 may include a battery box and multiple battery modules 2 disposed within the box. The battery box comprises an upper case 31 and a lower case 32. The upper case 31 can be positioned over the lower case 32 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.

[0174] In addition, the present application also provides an electrical device, which includes the battery provided in the present application. The battery cell, battery module, or battery pack can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.

[0175] As the electrical device, a battery cell, a battery module or a battery pack can be selected according to its usage requirements.

[0176] Figure 6 shows an example of an electric device. This device is a pure electric vehicle, hybrid electric vehicle, or plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the battery cells, a battery pack or battery module can be used.

[0177] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be lightweight and thin, and may use a battery cell as a power source.

[0178] 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.

[0179] Example 1

[0180] Preparation of organic polymer 1

[0181] Methyl methacrylate (the first monomer), ethylene (the second monomer), acrylonitrile (the third monomer), and acrylamide (the fourth monomer) were mixed uniformly in a mass ratio of 1:0.8:0.5:0.5. 1000 g of the mixed monomers, 30 g of sodium lauryl sulfate (an emulsifier), 10 g of ammonium persulfate (an initiator), and 1200 g of deionized water were added to a 5000 mL four-necked flask equipped with a mechanical stirrer, a thermometer, and a condenser. Emulsification was carried out at high speed stirring for 30 minutes. Under nitrogen protection, the temperature was raised to 75°C and the reaction was allowed to proceed for 4 hours. The pH was then adjusted to 6-8, and the temperature was lowered to below 40°C before discharging to obtain organic polymer 1.

[0182] Preparation of composite material 1

[0183] 1 kg of organic polymer 1 was added with 450 g of silicon dioxide and 1 kg of deionized water, and stirred for 1 hour. The mixture was then spray-dried to obtain composite material powder, which was then ground and pulverized to obtain composite material 1.

[0184] Preparation of isolation film 1

[0185] The composite material 1 is dispersed in water to obtain slurry, and the slurry is then coated on a PE film, and then water is removed by dry weight to obtain the isolation film 1.

[0186]

Lithium-ion battery preparation

[0187] (1) Preparation of positive electrode sheet

[0188] Polyvinylidene fluoride (PVDF), lithium iron phosphate (LFP), conductive carbon black, and N-methylpyrrolidone (NMP) were mixed in a mass ratio of 1.2:58.38:0.42:40 and stirred thoroughly to prepare a positive electrode slurry. 2 The loading amount is evenly coated on the positive electrode current collector aluminum foil, and then dried, cold pressed and cut to obtain the positive electrode sheet.

[0189] (2) Preparation of negative electrode sheet

[0190] Artificial graphite, conductive agent acetylene black, binder styrene butadiene rubber (SBR), thickener sodium carboxymethyl cellulose (CMC-Na) were added into deionized water in a mass ratio of 96.2:1.0:1.6:1.2, and stirred thoroughly to prepare a negative electrode slurry (solid content of 63%). 2 The loading amount is coated on the negative electrode current collector copper foil, and then dried, cold pressed and cut to obtain the negative electrode sheet.

[0191] (3) Preparation of electrolyte

[0192] At 25°C, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain a mixed solvent, and then LiPF6 is dissolved in the above mixed solvent to obtain an electrolyte, wherein the concentration of LiPF6 is 1 mol / L.

[0193] (4) The isolation membranes 1 described above were used.

[0194] (5) Preparation of lithium-ion batteries

[0195] The positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, wound, and cold-pressed to obtain a battery cell; the battery cell is placed in an outer package, and the prepared electrolyte is added. After packaging, standing, forming, aging, and other processes, a lithium-ion battery is obtained.

[0196] The methods for preparing lithium batteries in Examples 2 to 29 and Comparative Examples 1-2 are the same as in Example 1, except that the compositions of the composite materials used to prepare the separators are different, and the parameters in Table 1 are used.

[0197] The storage modulus, ionic conductivity of the separator, cold pressing bonding performance of the separator, and cycle performance of the lithium-ion battery of the composite materials obtained in Examples 1-29 and Comparative Examples 1-4 were characterized. The characterization results are shown in Table 2.

[0198] 1. Storage modulus test of composite materials: The composite materials were pressed into specimens with a size of 10 mm * 10 mm * 4 mm using a mold. The storage modulus of the specimens was then measured using a Perkin Elmer DMA 8000. The test conditions were: single cantilever mode, frequency 1 Hz, amplitude 0.5 mm, and temperature 25°C.

[0199] 2. Ion conductivity test of the isolation membrane: Cut the isolation membrane into 40mm×20mm test pieces, stack the cut isolation membranes into groups of 4 layers, use a commercial electrolyte (at 25°C, mix ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 1:1:1 to obtain a mixed solvent, and then dissolve LiPF6 in the above mixed solvent to obtain an electrolyte, wherein the concentration of LiPF6 is 1 mol / L) to completely wet the isolation membrane, and then assemble it into a symmetrical battery for testing in a glove box. The isolation membrane impedance is tested using an electrochemical workstation with a measurement range of 1Hz to 100,000Hz and an applied AC signal polarization of 5mV. The ionic conductivity can be calculated from the test results of the AC impedance using the following formula:

[0200] δ=1000L / RA

[0201] Where δ represents the ionic conductivity, unit: mS / cm; A represents the area of ​​the single-layer isolation membrane, unit: cm 2 , L represents the thickness of the test isolation film, the unit is cm, R represents the resistance of the test isolation film, the unit is Ω.

[0202] 3. Cycle performance test:

[0203] At 25°C, the prepared battery was charged at a constant current of 1 / 3C to 3.65V, then charged at a constant voltage of 3.65V to a current of 0.05C, left for 5 minutes, and then discharged at 1 / 3C to 2.5V. The obtained discharge capacity was recorded as the initial capacity C0. Repeat the above steps for the same battery and record the discharge capacity C of the battery after the nth cycle. n , then the battery capacity retention rate P after each cycle n =(C n / C0)×100%. The difference in cycle performance can be reflected by the battery capacity retention rate after 500 cycles.

[0204] 4. Cold press bonding test:

[0205] The battery negative electrode sheet and separator were stacked together and placed on a hot press. Pressing parameters were set at 25°C, 7t, and 15s to produce a bonded separator / negative electrode sheet sample. The separator / electrode sheet sample was cut into 150mm x 20mm rectangular strips. The electrode sheet side of the strip was affixed to a steel plate using double-sided tape. At one end of the strip, the separator and electrode sheet were separated by 2cm along the length to produce the test specimen.

[0206] The steel plate was held horizontally and secured with the lower clamp of a universal testing machine (Xie Qiang Instrument Manufacturing (Shanghai) Co., Ltd., Model CTM2100). The peeled end of the separator, as described above, was secured with the upper clamp of the universal testing machine and connected to a tensile testing machine. The test conditions were set to a tensile rate of 20 mm / min and a horizontal pull of 10 cm. Once the tensile force stabilized, the tensile force was recorded. The ratio of the tensile force to the sample width was used to determine the adhesion strength between the separator and the electrode.

[0207] Table 2

[0208] As can be seen from Table 2, the composite materials of Examples 1-29 include organic polymers and inorganic substances, and the polymerization monomers of the organic polymers include at least a first monomer and a second monomer. The storage modulus of the obtained composite material is between 100 MPa and 1000 MPa, and the cold pressing adhesion between the isolation membrane containing the composite material and the negative electrode plate, the ionic conductivity of the isolation membrane, and the capacity retention rate of the battery are all higher than those of Comparative Examples 1-4. This shows that when the composite material with the composition and storage modulus of the present application is used for the isolation membrane, cold pressing bonding between the isolation membrane and the electrode plate can be achieved, and the bonding force is appropriate, thereby improving the cycle performance of the battery.

[0209] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0210] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A composite material, characterized in that, Comprising an organic polymer and an inorganic substance, the polymerization monomers of the organic polymer include a first monomer and a second monomer, and the structural formula of the first monomer includes: Among them, R1 includes a hydrogen atom or an alkyl group with 1 - 6 carbon atoms, R2 includes a hydrogen atom, a substituted or unsubstituted alkyl group with 1 - 21 carbon atoms, a cycloalkyl group with 3 - 6 carbon atoms, an epoxyalkyl group with 3 - 6 carbon atoms, a substituted or unsubstituted isobornyl group, and the substituent in the substituted alkyl group with 1 - 15 carbon atoms includes a hydroxyl group; The structural formula of the second monomer includes: Among them, R6, R7, R8, and R9 each independently include a hydrogen atom, a substituted or unsubstituted phenyl group, a substituted or unsubstituted cycloalkyl group, a straight-chain or branched-chain alkyl or alkenyl group, and the storage modulus of the composite material is 100 MPa - 1000 MPa.

2. The composite material according to claim 1, characterized in that, The storage modulus of the composite material is 200 MPa - 800 MPa.

3. The composite material according to claim 1, characterized in that The mass ratio of the first monomer to the second monomer is 1:0.55 - 1.

4. The composite material according to any one of claims 1 to 3, characterized in that, The first monomer includes at least one of acrylic acid, methacrylic acid, crotonic acid, heptenoic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, or vinyl acetate.

5. The composite material according to any one of claims 1-4, characterized in that, The second monomer includes at least one of ethylene, styrene, butadiene, or isoprene.

6. The composite material according to any one of claims 1-5, characterized in that, The polymerization monomer of the organic polymer further includes a third monomer, and the third monomer includes an unsaturated nitrile group.

7. The composite material according to claim 6, wherein, The structural formula of the third monomer includes: Among them, R3 includes a hydrogen atom or an alkyl group with 1 - 6 carbon atoms.

8. The composite material according to claim 6 or 7, characterized in that, The third monomer includes at least one of acrylonitrile, methacrylonitrile, or ethylacrylonitrile.

9. The composite material according to any one of claims 6-8, characterized in that, The weight ratio of the first monomer, the second monomer, and the third monomer is 1:0.55 - 1:0.01 - 0.

8.

10. The composite material according to any one of claims 6-9, characterized in that, The weight ratio of the first monomer, the second monomer, and the third monomer is 1:0.6 - 0.8:0.05 - 0.

6.

11. The composite material according to any one of claims 6-10, characterized in that, The polymerization monomer of the organic polymer further includes a fourth monomer, and the fourth monomer includes an unsaturated amide group.

12. The composite material according to claim 11, wherein The structural formula of the fourth monomer includes: Among them, R4 includes a hydrogen atom or an alkyl group with 1 - 6 carbon atoms, and R5 includes a hydrogen atom, a hydroxyl-substituted alkyl group with 1 - 6 carbon atoms, or an alkoxy group with 1 - 6 carbon atoms.

13. The composite material according to claim 11 or 12, characterized in that, The fourth monomer includes at least one of acrylamide, N-hydroxymethylacrylamide, or N-butoxymethylacrylamide.

14. The composite material according to claim 12 or 13, characterized in that, The weight ratio of the first monomer, the second monomer, the third monomer, and the fourth monomer is 1:0.55 - 1:0.01 - 0.8:0.05 - 0.

7.

15. The composite material according to any one of claims 12 - 14, characterized in that, The weight ratio of the first monomer, the second monomer, the third monomer, and the fourth monomer is 1:0.6 - 0.8:0.05 - 0.6:0.1 - 0.

5.

16. The composite material according to any one of claims 1 to 15, characterized in that, Meet at least one of the following conditions: The particle size of the composite material satisfies: 2 μm ≤ D50 ≤ 15 μm; The particle size distribution of the composite material = (D90 - D10) / D50, and the particle size distribution of the composite material is less than or equal to 5; The particle size of the inorganic substance is 0.0001 μm - 2 μm.

17. The composite material according to any one of claims 1-16, characterized in that, The inorganic substance is attached to the surface of the organic polymer and / or dispersed inside the organic polymer.

18. The composite material according to any one of claims 1-17, characterized in that, The inorganic substance includes at least one of silicon oxide, aluminum oxide, calcium oxide, zinc oxide, magnesium oxide, sodium sulfate, sodium benzoate, calcium carbonate and its modified materials.

19. The composite material according to any one of claims 1-18, characterized in that, The inorganic substance includes silicon dioxide, and the particle size of the silicon dioxide is 0.0001 μm - 2 μm.

20. The composite material according to any one of claims 1-19, characterized in that, Based on the mass of the composite material, the mass proportion of the organic polymer is 50% - 99.9%.

21. The composite material according to any one of claims 1-20, characterized in that, The outer surface of the composite material is uneven.

22. A method for preparing a composite material, characterized in that, Comprising: Mix an organic polymer and an inorganic substance to obtain a composite material. The polymerization monomers of the organic polymer include a first monomer and a second monomer. The structural formula of the first monomer includes: Wherein, R1 includes a hydrogen atom or an alkyl group with 1 - 6 carbon atoms, and R2 includes a hydrogen atom, a substituted or unsubstituted alkyl group with 1 - 21 carbon atoms, a cycloalkyl group with 3 - 6 carbon atoms, an epoxyalkyl group with 3 - 6 carbon atoms, a substituted or unsubstituted isobornyl group, and the substituent in the substituted alkyl group with 1 - 15 carbon atoms includes a hydroxyl group; The structural formula of the second monomer includes: Wherein, R6, R7, R8, and R9 each independently include a hydrogen atom, a substituted or unsubstituted phenyl group, a substituted or unsubstituted cycloalkyl group, a straight-chain or branched-chain alkyl group or alkenyl group, and the storage modulus of the composite material is 100 MPa - 1000 MPa.

23. An isolation film, characterized in that, Comprising the composite material according to any one of claims 1 - 21 or the composite material obtained by the method according to claim 22.

24. The separator film according to claim 23, wherein The ionic conductivity of the separator membrane is 0.3 mS·cm -1 -0.6 mS·cm -1 .

25. A pole piece, characterized in that, Comprising the composite material according to any one of claims 1 - 21 or the composite material obtained by the method according to claim 22.

26. A battery, characterized in that, Comprising the separator according to claim 23 or 24 and / or the electrode sheet according to claim 25.

27. An electrical device, characterized in that, Comprising the battery according to claim 26.

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