Separator with self-laminating coating, method for preparing the same, and related secondary battery and power using device

Abstract

The application discloses a diaphragm with a self-layering coating, a preparation method thereof and a related secondary battery and an electric device. A battery diaphragm comprises a base film and a coating arranged on at least one surface of the base film, wherein the coating is obtained by one-time coating of a slurry, the slurry comprises an amino-modified organic silicon polymer, an amino-modified inorganic filler and an epoxy resin, the content of the amino-modified organic silicon polymer on the upper surface of the coating is denoted as V1, the content of the amino-modified organic silicon polymer on the lower surface of the coating is denoted as V2, and V1>V2. According to the embodiment of the application, the heat resistance and the adhesion of the base film can be simultaneously improved by one-time coating, and the heat shrinkage resistance of the diaphragm can be improved by the amino-modified organic silicon polymer, the amino-modified inorganic filler and the epoxy resin.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of batteries, and particularly relates to a separator with a self-layering coating, a preparation method thereof, and a related secondary battery and power utilization device. BACKGROUND

[0002] At present, in order to take into account the heat resistance and bonding strength of the coated separator, two coatings are often needed. That is, a layer of heat-resistant inorganic filler is first roll-coated on the surface of the base film to ensure a small heat shrinkage rate, and then a roll-coated large particle glue or a sprayed PVDF is used to improve the bonding strength of the separator, so as to resist the risk of positive and negative short circuits that easily occurs under the condition of external impact or temperature rise during use.

[0003] However, it is obvious that two coatings have a high production cost. In addition, the inorganic particles in the coating are connected mainly by the adhesive. When the external temperature continues to increase, the base film shrinkage tendency becomes larger, and the adhesive molecular chain movement becomes easier, thereby causing the heat shrinkage resistance to fail. SUMMARY

[0004] The embodiments of the present application provide a separator with a self-layering coating, a preparation method thereof, and a related secondary battery and power utilization device, which can simultaneously improve the heat resistance and bonding strength of the base film by one coating, and improve the heat shrinkage resistance of the separator by using an amino-modified organic silicon polymer, an amino-modified inorganic filler, and an epoxy resin.

[0005] In a first aspect, the embodiments of the present application provide a separator with a self-layering coating, comprising a base film and a coating arranged on at least one surface of the base film, wherein the coating is obtained by one coating of a slurry, the slurry comprises an amino-modified organic silicon polymer, an amino-modified inorganic filler, and an epoxy resin, the content of the amino-modified organic silicon polymer on the upper surface of the coating is denoted as V1, the content of the amino-modified organic silicon polymer on the lower surface of the coating is denoted as V2, and V1>V2.

[0006] In any embodiment of the present application, the thickness of the upper surface of the coating is 0.1% to 20% of the thickness of the coating, and the thickness of the lower surface of the coating is 0.1% to 20% of the thickness of the coating.

[0007] In any embodiment of the present application, the content of the amino-modified organic silicon polymer on the upper surface of the coating can be characterized by the silicon element of energy spectrum, and other characterization methods that can accurately identify the content of the amino-modified organic silicon polymer in the coating can also be used.

[0008] In any embodiment of the present application, the amino-modified organic silicon polymer, the amino-modified inorganic filler, and the epoxy resin are bonded in the coating through amino and epoxy groups to form a three-dimensional network cross-linked structure.

[0009] In any embodiment of the present application, the mass ratio of the amino-modified organosilicon polymer, the amino-modified inorganic filler and the epoxy resin is (2-10):1800:(80-120), wherein the mass of the amino-modified organosilicon polymer is calculated based on the mass of the raw material KH550 / KH560 added in the preparation of the amino-modified organosilicon polymer.

[0010] In any embodiment of the present application, the amino-modified organosilicon polymer comprises an amino-modified organosilicon pressure-sensitive adhesive.

[0011] In any embodiment of the present application, the amino-modified inorganic filler comprises at least one of a silane-modified alumina, a silane-modified boehmite, a silane-modified magnesium hydroxide, a silane-modified silica, a silane-modified titanium dioxide, a silane-modified zirconia, a silane-modified hydrotalcite and a silane-modified montmorillonite.

[0012] In any embodiment of the present application, the epoxy resin comprises a bisphenol A type epoxy resin, and the model of the bisphenol A type epoxy resin comprises at least one of E-20, E-21, E-42, E-44, E-51 and E-54.

[0013] In any embodiment of the present application, the coating further comprises a curing agent, and the curing agent comprises an amine curing agent.

[0014] In any embodiment of the present application, the amine curing agent comprises at least one of a fatty amine, a modified alicyclic amine curing agent, a cashew phenol modified fatty amine curing agent and a polyamide curing agent.

[0015] In any embodiment of the present application, the thickness of the coating is 1-6 μm.

[0016] In any embodiment of the present application, the separator satisfies at least one of the following conditions (1) to (4): (1) the longitudinal heat shrinkage rate of the separator at 150℃ for 1h is 0.80%-1.10%; (2) the transverse heat shrinkage rate of the separator at 150℃ for 1h is 0.40%-0.60%; (3) the adhesive strength of the separator is 50-70 N / m; and (4) the air permeability of the separator is 160-190 s / 100cc.

[0017] In a second aspect, the embodiments of the present application provide a preparation method of a battery separator, comprising the following steps: preparing a slurry, mixing an amino-modified organosilicon polymer, an amino-modified inorganic filler and an epoxy resin in a solvent according to a predetermined ratio to prepare a slurry; coating the slurry on at least one surface of a base film to form a coating layer and dry to obtain a separator.

[0018] In any embodiment of the present application, the solvent comprises at least one of dimethylbenzene, n-butanol, methyl isobutyl ketone, butanone, acetone, tetrahydrofuran, butyl acetate and ethyl acetate in the preparation of the slurry.

[0019] In any embodiment of the present application, the curing agent is further included in the slurry, and the mass ratio of the curing agent to the epoxy resin is (6-10):(60-120).

[0020] In any embodiment of the present application, the preparation method of the amino-modified organic silicon polymer comprises: mixing the material containing the coupling agent and the solvent, adjusting the pH of the mixed solution to 2-4, and raising the temperature of the mixed solution to 40-80℃, and then refluxing and reacting for 4-8h, and then distilling at 50-80℃ under reduced pressure to obtain polysiloxane; mixing the polysiloxane, the organic silicon polymer and the solvent according to the preset ratio, and then reacting at 90-120℃ for 2-5h, and then adding the polymer initiator and reacting for 0.5-3h to obtain the amino-modified organic silicon polymer.

[0021] In any embodiment of the present application, the mass ratio of the polysiloxane to the organic silicon polymer is (2-8):(80-220).

[0022] In any embodiment of the present application, the organic silicon polymer comprises at least one of the end hydroxyl silicone rubber and the organic silicon resin.

[0023] In any embodiment of the present application, the number average molecular weight of the end hydroxyl silicone rubber is 500-200,000.

[0024] In any embodiment of the present application, the organic silicon resin is a polyalkyl organic silicon resin, preferably a polymethyl organic silicon resin, and further preferably a methyl MQ resin.

[0025] In any embodiment of the present application, the number average molecular weight of the methyl MQ resin is 1000-8000.

[0026] In any embodiment of the present application, the M / Q value of the methyl MQ resin is 0.2-1.

[0027] In any embodiment of the present application, the polymer initiator is a free radical initiator.

[0028] In any embodiment of the present application, the preparation method of the amino-modified inorganic filler comprises: mixing the inorganic filler, the coupling agent and the solvent according to the preset ratio, and then reacting at 40-70℃ for 20-50min, and then reacting at 120-170℃ for 10-30min to obtain the amino-modified inorganic filler.

[0029] In any embodiment of the present application, the mass ratio of the inorganic filler to the coupling agent is 1800:(15-20).

[0030] In any embodiment of the present application, the coupling agent comprises KH-550 and / or KH560.

[0031] In any embodiment of the present application, in the coating, the coating method comprises roller coating or spraying.

[0032] In any embodiment of the present application, in the coating, the thickness of the base film is not limited and can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or 16 μm.

[0033] In any embodiment of the present application, in the coating, the coating speed is 40-150 m / min.

[0034] In any embodiment of the present application, the winding method can be at least one of PET release film winding, deviation correction winding, or adhesive tape winding, and post-slitting winding.

[0035] In a third aspect, the embodiments of the present application provide a secondary battery comprising the separator described above or prepared by the preparation method described above.

[0036] In a fourth aspect, the embodiments of the present application provide an electric device comprising the secondary battery described above.

[0037] The separator with a self-layered coating, the preparation method thereof, and the related secondary battery and electric device of the embodiments of the present application can realize self-layering of the amino-modified organosilicon polymer and the epoxy resin by one-time coating of the coating containing the amino-modified organosilicon polymer and the epoxy resin, because the amino-modified organosilicon polymer and the epoxy resin have different surface energies. The amino-modified organosilicon polymer is gathered on the upper surface of the coating, and the epoxy resin is gathered on the lower surface of the coating, so that the base film can have good heat resistance and good adhesion between the coating and the base film after one-time coating, thereby achieving the purpose of reducing the coating times and saving the cost. The three-dimensional network cross-linking structure is formed between the amino-modified organosilicon polymer, the amino-modified inorganic filler, and the epoxy resin through the bonding reaction of the amino groups contained in the amino-modified organosilicon polymer and the amino-modified inorganic filler and the epoxy groups contained in the epoxy resin, so as to replace the van der Waals force in the traditional method with the chemical bond between the inorganic filler and the epoxy resin (adhesive), to enhance the interaction force between the inorganic filler molecules, to reduce the movement of the inorganic filler molecules caused by the increase of the external temperature, and to improve the stability of the inorganic filler, thereby improving the heat shrinkage resistance of the separator. DETAILED DESCRIPTION

[0038] In order to more clearly understand the above objectives, features and advantages of the present application, the solutions of the present application will be further described below. It should be explained that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict, if necessary.

[0039] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. The present application, however, can be practiced without the specific details. In other instances, well-known methods have not been described in detail in order not to unnecessarily obscure aspects of the present application.

[0040] The ranges disclosed herein are defined by the lower and upper limits of the range, given by selecting a lower limit and an upper limit, which define the boundaries of the particular range. The ranges defined in this manner can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. In addition, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4 and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise stated, a numerical range "a-b" indicates a shorthand way of describing all of the real combinations between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all of the real numbers between "0-5" have been listed herein, and "0-5" is just a shorthand way of describing these numerical combinations. In addition, when it is stated that a parameter is an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0041] If not specifically stated, all the embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0042] If not specifically stated, all the technical features and optional technical features of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0043] If not otherwise specified, all steps of the present application can be carried out in sequence or randomly, preferably in sequence. For example, the method comprising steps (a) and (b) means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method comprising step (c) means that step (c) can be added to the method in any sequence, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0044] If not otherwise specified, all raw materials in the embodiments of the present application are purchased through commercial channels.

[0045] If not otherwise specified, the present application uses conventional test methods or test methods recommended by the instrument.

[0046] Generally, a secondary battery comprises an electrode assembly and an electrolyte, the electrode assembly comprises a positive electrode sheet, a negative electrode sheet and a separator, the separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly plays a role in preventing the positive electrode and the negative electrode from short-circuiting, and at the same time can make the active ions pass through the loop freely.

[0047] With the application and popularization of secondary batteries, in order to balance the heat resistance and adhesion strength of the separator, two coatings are often needed. A layer of heat-resistant inorganic filler is first roller-coated on the surface of the base film to ensure a small thermal shrinkage rate, and then a large-particle adhesive is roller-coated, PVDF is sprayed, etc. to improve the adhesion of the separator, so as to resist the risk of positive and negative short-circuiting easily occurring under the condition of external impact or temperature rise during use, and thus increase the production cost. The inorganic filler in the heat-resistant layer can bring heat-resistant performance to the separator. In order to make the inorganic filler molecules adhere to each other, an adhesive is usually used, such as commonly used acrylate, to adhere the inorganic filler molecules to each other by van der Waals force. However, with the increase of temperature, on the one hand, high temperature will accelerate the movement of the molecular chains of the adhesive, destroy the van der Waals force between the inorganic filler molecules, and make the inorganic filler layer lose the supporting effect on the base film, which will cause obvious thermal shrinkage in macroscopic view; on the other hand, high temperature will also increase the shrinkage tendency of the base film, and thus may lose the supporting effect on the coating. Thus, the positive electrode and the negative electrode in the battery directly contact each other to cause internal short-circuiting, and thus increase the safety risk of the secondary battery.

[0048] To solve the above problems, the inventors of the present application surprisingly found in the research process that by providing a coating layer including an amino-modified organic silicon polymer, an amino-modified inorganic filler and an epoxy resin on the surface of the base film, and making the surface energy of the amino-modified organic silicon polymer lower than the surface energy of the epoxy resin, the diaphragm can have good heat resistance and good adhesion between the coating layer and the base film at the same time by one coating, and the heat shrinkage resistance of the diaphragm can be improved by establishing a three-dimensional cross-linking structure among the organic silicon polymer, the inorganic filler and the epoxy resin.

[0049] Diaphragm

[0050] The embodiment of the present application provides a diaphragm with a self-layering coating, including a base film and a coating layer provided on at least one (may be one or two) surface of the base film, wherein the coating layer is obtained by one coating of a slurry, the slurry includes an amino-modified organic silicon polymer, an amino-modified inorganic filler and an epoxy resin, the content of the amino-modified organic silicon polymer on the upper surface of the coating layer is denoted as V1, and the content of the amino-modified organic silicon polymer on the lower surface of the coating layer is denoted as V2, V1>V2.

[0051] In the present application, the content of the amino-modified organic silicon polymer on the upper surface of the coating layer can be characterized by the energy spectrum silicon element, and other characterization methods that can accurately identify the content of the amino-modified organic silicon polymer in the coating layer can also be used.

[0052] In the present application, the content of the energy spectrum silicon element on the upper surface of the coating layer or the lower surface of the coating layer can be detected by using the method known in the art.

[0053] Due to the difference in surface energy between the amino-modified organic silicon polymer and the epoxy resin, the self-layering phenomenon occurs. When the self-layering coating containing the amino-modified organic silicon polymer, the amino-modified inorganic filler and the epoxy resin is coated on the base film, with the volatilization of the solvent, the amino-modified organic silicon polymer migrates to the upper surface of the diaphragm, and the epoxy resin migrates to the lower surface of the diaphragm. The amino-modified organic silicon polymer on the upper surface of the diaphragm can provide good adhesion between the diaphragm and the electrode, and since it is concentrated on the upper surface of the diaphragm, it will not block the pores of the base film on the lower surface of the diaphragm, so that the diaphragm has good porosity; the epoxy resin on the lower surface of the diaphragm can provide the bonding strength between the inorganic fillers and the adhesion between the coating layer and the base film, and the coating layer in the present application also has good heat resistance.

[0054] The thickness of the upper surface of the coating layer is 0.1% to 20% of the thickness of the coating layer, and the thickness of the lower surface of the coating layer is 0.1% to 20% of the thickness of the coating layer.

[0055] The inventors found in the process of researching the heat resistance of the separator and the coating process that people often need to perform two coatings in order to balance the heat resistance and the bonding strength of the separator. In order to bond the inorganic filler molecules to each other, an adhesive is usually used, such as the commonly used acrylate, to bond the inorganic filler molecules to each other by Van der Waals force. However, the increase in the number of coating processes will increase the production cost, and the acrylate adhesive will result in poor heat resistance of the separator.

[0056] The inventors found in further research that the heat resistance and the bonding strength of the separator can be improved simultaneously by one coating of a coating containing an amino-modified silicone polymer and an epoxy resin, and the amino-modified silicone polymer and the epoxy resin can be self-layered into a bonding layer and a heat-resistant layer due to their different surface energies, so that the base film can improve the heat resistance and the bonding strength of the separator after one coating, thereby achieving the purpose of reducing the number of coating and saving cost; and the amino-modified silicone polymer, the amino group contained in the amino-modified inorganic filler, and the epoxy group contained in the epoxy resin are bonded by a chemical bond, thereby forming a three-dimensional network cross-linked structure between the amino-modified silicone polymer, the amino-modified inorganic filler, and the epoxy resin, replacing the Van der Waals force in the traditional process, enhancing the force between the inorganic filler molecules, reducing the movement of the inorganic filler molecules caused by the increase of the external temperature, thereby improving the stability of the inorganic filler, and further improving the heat shrinkage resistance of the separator.

[0057] The material of the base film is not particularly limited in the present application, and any known base film with good chemical stability and mechanical stability can be selected, for example, the base film can include at least one of a porous polyolefin-based resin film (such as at least one of polyethylene, polypropylene, and polyvinylidene fluoride), a porous glass fiber, and a porous non-woven fabric. The base film can be a single-layer film or a multi-layer composite film. When the base film is a multi-layer composite film, the materials of the layers can be the same or different.

[0058] In some embodiments, the amino-modified silicone polymer, the amino-modified inorganic filler, and the epoxy resin are bonded in the coating layer by the amino and epoxy groups to form a three-dimensional network cross-linked structure.

[0059] The three-dimensional network cross-linked structure refers to a network cross-linked structure composed of multiple cross-linked polymer chains in three-dimensional space. In the present application, the amino functional group in the amino-modified silicone polymer and the amino-modified inorganic filler and the epoxy group in the epoxy resin are bonded by a bonding reaction to generate the three-dimensional network cross-linked structure, which can bond the silicone polymer, the inorganic filler, and the epoxy resin through a chemical bond, and the chemical bond is not easy to break at high temperature, thereby improving the stability of the silicone polymer, the inorganic filler, and the epoxy resin at high temperature, and further improving the heat resistance of the separator.

[0060] In some embodiments, the mass ratio of the amino-modified silicone polymer, the amino-modified inorganic filler, and the epoxy resin is (2-10):1800:(80-120), preferably, the mass ratio of the amino-modified silicone polymer, the amino-modified inorganic filler, and the epoxy resin is (2-8):1800:(90-110), further preferably (3-6):1800:100, for example, it can be 3:1800:100, 3.75:1800:100, 4:1800:100, 5:1800:100, 5.3:1800:100, 6:1800:100, or 8:1800:100, wherein the mass of the amino-modified silicone polymer is calculated based on the mass of the raw material KH550 / KH560 added in the preparation of the amino-modified silicone polymer.

[0061] In some embodiments, the amino-modified silicone polymer comprises an amino-modified silicone pressure-sensitive adhesive.

[0062] In some embodiments, the amino-modified inorganic filler comprises at least one of a silane-modified alumina, a silane-modified boehmite, a silane-modified magnesium hydroxide, a silane-modified silica, a silane-modified titanium dioxide, a silane-modified zirconia, a silane-modified hydrotalcite, and a silane-modified montmorillonite. Preferably, the amino-modified inorganic filler is a silane-modified boehmite.

[0063] In some embodiments, the epoxy resin comprises a bisphenol A type epoxy resin, and the model number of the bisphenol A type epoxy resin comprises at least one of E-20, E-21, E-42, E-44, E-51, and E-54.

[0064] In some embodiments, the coating layer further comprises a curing agent, and the curing agent comprises an amine curing agent. In the present application, the curing agent can cure and harden the coating in the coating layer, so that the coating can form a relatively hard protective film after a certain period of curing. At the same time, the curing agent can also increase the hardness and wear resistance of the coating layer, improve the adhesion and chemical resistance of the coating layer, and prolong the service life of the coating layer.

[0065] In some embodiments, the amine curing agent comprises at least one of a fatty amine, a modified alicyclic amine curing agent, a cashew phenol modified fatty amine curing agent, and a polyamide curing agent. Preferably, the amine curing agent comprises a fatty amine, further preferably a polyamine, and still further preferably ethylenediamine.

[0066] In some embodiments, the thickness of the coating layer is 1-6 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or 6 μm. The coating layer of the present application can significantly improve the heat resistance of the separator, so that a thinner porous base film can be selected, thereby helping to improve the energy density of the secondary battery.

[0067] In some embodiments, the heat shrinkage in the longitudinal direction of the separator at 150℃ for 1h is 0.80% to 1.10% (for example, it can be 0.91%, 0.94%, 0.98%, 1.02% or 1.07%).

[0068] In some embodiments, the heat shrinkage in the transverse direction of the separator at 150℃ for 1h is 0.40% to 0.60% (for example, it can be 0.41%, 0.44%, 0.51%, 0.53% or 0.56%).

[0069] The separator of the present application has low heat shrinkage in both the transverse and longitudinal directions at high temperature of 150℃, thereby being capable of improving the safety performance of the secondary battery.

[0070] In some embodiments, the bonding strength of the separator is 50 to 70 N / m (for example, it can be 50 N / m, 54 N / m, 59 N / m, 63 N / m or 68 N / m).

[0071] In some embodiments, the air permeability of the separator is 160 to 190 s / 100cc (for example, it can be 162 s / 100cc, 169 s / 100cc, 175 s / 100cc, 178 s / 100cc or 186 s / 100cc).

[0072] The separator of the present application has good air permeability, thereby being capable of improving the ion conductivity and the capacity performance of the secondary battery.

[0073] In the present application, the average particle size of the material is the meaning known in the art, and can be measured by using the instruments and methods known in the art. For example, the material or the separator can be measured by a scanning electron microscope, a transmission electron microscope, a particle size distribution instrument to obtain a picture, and a plurality of (for example, more than 10) test particles are randomly selected from the picture, and the average value of the shortest diagonal length of the particles is taken as the average particle size.

[0074] In the present application, the specific surface area of the material is the meaning known in the art, and can be measured by using the instruments and methods known in the art. For example, it can be tested by using the nitrogen adsorption specific surface area analysis test method according to GB / T 19587-2017, and calculated by using the BET (Brunauer Emmett Teller) method. Alternatively, the nitrogen adsorption specific surface area analysis test can be performed by using the Tri-Star 3020 type specific surface area pore size analyzer of the American Micromeritics company.

[0075] In the present application, the heat shrinkage, the adhesive strength and the air permeability of the separator all have the meanings known in the art and can be measured by the methods known in the art. For example, the tests can be performed according to the standard GB / T36363-2018.

[0076] It should be noted that the coating parameters (such as thickness, etc.) of the above-mentioned separator are the coating parameters of the single side of the base film. When the coating is arranged on both sides of the base film, the coating parameters of any one side thereof meeting the present application are considered to fall within the protection scope of the present application.

[0077] Preparation method

[0078] A preparation method of a battery separator, comprising the following steps: S1, preparing a slurry, mixing an amino-modified silicone polymer, an amino-modified inorganic filler and an epoxy resin in a solvent according to a predetermined proportion to prepare a slurry; S2, coating the slurry on at least one (may be one or two) surface of a base film to form a coating layer and dry to obtain a separator.

[0079] In some embodiments, in step S1, the solvent comprises at least one of xylene, n-butanol, methyl isobutyl ketone, butanone, acetone, tetrahydrofuran, butyl acetate and ethyl acetate.

[0080] In some embodiments, in step S1, the slurry further comprises a curing agent, and the mass ratio of the curing agent to the epoxy resin is (6-10):(60-120), preferably, the mass ratio of the curing agent to the epoxy resin is (7-9):(90-110), further preferably (7-9):100, for example, it can be 8:100, 8:110, 8:120, 6:100, 6:110 or 6:120. Alternatively, the mass ratio of the curing agent to the epoxy resin is 8:100.

[0081] In some embodiments, in step S1, the preparation method of the amino-modified silicone polymer comprises: S11, after mixing the material containing the coupling agent and the solvent, adjusting the pH of the mixed solution to 2-4, preferably pH=3, and raising the temperature of the mixed solution to 40-80℃, preferably the temperature of the mixed solution is raised to 60℃, and then refluxing for 4-8h, and then distilling under reduced pressure at 50-80℃ to obtain polysiloxane; S12, mixing the polysiloxane and the organic silicon polymer according to a predetermined proportion, reacting at 90-120℃ for 2-5h, then adding a polymer initiator and reacting for 0.5-3h to obtain the amino-modified silicone polymer.

[0082] In the present application, the polysiloxane is obtained by hydrolyzing the coupling agent KH-550 or the coupling agent KH560, and then the hydroxyl-terminated silicone rubber, the silicone resin and the polymer initiator are added to react to obtain the amino-modified silicone pressure-sensitive adhesive solution.

[0083] In some embodiments, the mass ratio of polysiloxane and silicone polymer is (2-8):(80-220), preferably, the mass ratio of polysiloxane and silicone polymer is (2-6):(80-120), further preferably (2-5):(90-110), for example, it can be 2:90, 3:90, 4:90, 5:90, 2:100, 3:100, 4:100, 5:100, 2:110, 3:110, 4:110 or 5:110. Among them, in S12, the silicone polymer includes at least one (one or two) of hydroxyl-terminated silicone rubber and silicone resin. The number average molecular weight of the hydroxyl-terminated silicone rubber is 500-2000 (for example, it can be 500, 800, 1000, 1200, 1400, 1600, 1800, 2000), preferably 800-1500, further preferably 1000. The silicone resin is a polyalkyl silicone resin, preferably a polymethyl silicone resin, further preferably a methyl MQ resin. The number average molecular weight of the methyl MQ resin is 1000-8000 (for example, it can be 1000, 2000, 3000, 4000, 5000, 6000, 7000 or 8000), preferably 1000-5000, further preferably 2000. The M / Q value of the methyl MQ resin is 0.2-1 (for example, it can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1), preferably 0.2-0.8, further preferably 0.6. The solvent is xylene, the polymer initiator is a free radical initiator, further preferably a peroxide initiator, and further preferably BPO. In S12, in order to better obtain the amino-modified silicone polymer, the silicone polymer, polysiloxane can be dissolved in the solvent first, reacted at a preset temperature for a preset time, then a solution of polymer initiator dissolved in the solvent is added, and the reaction is continued to obtain the amino-modified silicone pressure-sensitive adhesive solution. At this time, the mass ratio of polysiloxane, hydroxyl-terminated silicone rubber and silicone resin is (2-10):(30-100):(50-130), preferably, the mass ratio of polysiloxane, hydroxyl-terminated silicone rubber and silicone resin is (2-8):(30-80):(50-130), further preferably (3-6):(40-80):(60-120), for example, it can be 2:40:60, 3:40:60, 3.75:40:60, 4:40:60, 5:40:60, 5.3:70:105, 6:60:90, 6:80:120.

[0084] In some embodiments, more preferably, the separator has a better bonding strength and a smaller heat shrinkage value (MD and TD), the mass ratio of polysiloxane, hydroxyl-terminated silicone rubber and silicone resin is (2-10):(30-100):(90-130), preferably (5-6):(60-80):(105-120).

[0085] In some embodiments, more preferably, the separator has a lower air permeability value, the mass ratio of polysiloxane, hydroxyl-terminated silicone rubber and silicone resin is (2-10):(30-80):(60-80), preferably (3-4):(40-50):(60-80).

[0086] In some embodiments, more preferably, the separator has a lower air permeability value, a higher bonding strength and a smaller heat shrinkage value (MD and TD), the mass ratio of polysiloxane, hydroxyl-terminated silicone rubber and silicone resin is (4-8):(30-80):(70-100), preferably 6:60:90.

[0087] In some embodiments, in step S1, the method for preparing the amino-modified inorganic filler comprises: S13, mixing the inorganic filler, the coupling agent and the solvent according to a preset ratio, and then reacting at 40-70°C for 20-50 min, and then reacting at 120-170°C for 10-30 min to obtain the amino-modified inorganic filler.

[0088] In some embodiments, the mass ratio of the inorganic filler and the coupling agent is 1800:(15-20) (for example, it can be 1800:15, 1800:16, 1800:17, 1800:18, 1800:19 or 1800:20), preferably 1800:(16-19).

[0089] In S13, in order to better obtain the amino-modified inorganic filler, the inorganic filler can be mixed with the solvent first, and then a preset content of the coupling agent is added.

[0090] In some embodiments, the coupling agent comprises KH-550 and / or KH560.

[0091] In some embodiments, in the coating, the coating method comprises roller coating or spraying.

[0092] In some embodiments, in the coating, the thickness of the base film is not limited, and can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm.

[0093] In some embodiments, in the coating, the coating vehicle speed is 40-150 m / min, for example, can be 40 m / min, 50 m / min, 60 m / min, 70 m / min, 80 m / min, 90 m / min, 100 m / min, 110 m / min, 120 m / min, 130 m / min, 140 m / min or 150 m / min.

[0094] In some embodiments, the winding mode can be at least one of PET release film winding, deviation correction winding, or adhesive tape winding, and post-slitting winding.

[0095] Some raw materials and their content parameters used in the preparation method of the diaphragm of the present application can refer to the diaphragm of the embodiments of the present application, which will not be repeated here.

[0096] Secondary battery

[0097] A secondary battery includes the battery diaphragm described above or the battery diaphragm prepared by the preparation method described above.

[0098] The secondary battery is also called a rechargeable battery or a storage battery, which refers to a battery that can continue to be used by activating the active material through charging after the battery is discharged. Generally, the secondary battery includes an electrode assembly and an electrolyte, the electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a diaphragm, the diaphragm is arranged between the positive electrode sheet and the negative electrode sheet, mainly plays a role of preventing the positive electrode and the negative electrode from short-circuiting, and can also make active ions pass through.

[0099] The present application does not have a particular limitation on the type of secondary battery, for example, the secondary battery can be a lithium ion battery, a sodium ion battery, etc., in particular, the secondary battery can be a lithium ion secondary battery.

[0100] The secondary battery of the present application includes the diaphragm of the embodiments of the present application or the diaphragm prepared by the method of the embodiments of the present application, and the diaphragm is arranged between the positive electrode sheet and the negative electrode sheet. Optionally, at least one side of the diaphragm close to the negative electrode sheet has a coating of the present application. Thus, the secondary battery of the present application can have high energy density, high thermal safety performance, and long service life.

[0101]

Positive electrode sheet

[0102] In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector and including a positive electrode active material. For example, the positive electrode current collector has two opposite surfaces in the thickness direction of itself, and the positive electrode film layer is arranged on any one or both of the two opposite surfaces of the positive electrode current collector.

[0103] When the secondary battery of the present application is a lithium ion battery, the positive active material can include, but is not limited to, at least one of lithium-containing transition metal oxides, lithium-containing phosphates, and modified compounds thereof. Examples of the lithium-containing transition metal oxides can include, but are not limited to, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and modified compounds thereof. Examples of the lithium-containing phosphates can include, but are not limited to, at least one of lithium iron phosphate, a composite of lithium iron phosphate and carbon, lithium manganese phosphate, a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium manganese iron phosphate and carbon, and modified compounds thereof.

[0104] As an example, the positive active material for a lithium ion battery can include at least one of LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.15 Al 0.05 O2, LiFePO4, LiMnPO4.

[0105] When the secondary battery of the present application is a sodium ion battery, the positive active material can include, but is not limited to, at least one of sodium-containing transition metal oxides, polyanion materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), Prussian blue-based materials.

[0106] As an example, the positive active material for a sodium ion battery can include NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3O2, NaFePO4, NaMnPO4, NaCoPO4, at least one of Prussian blue materials.

[0107] In the present application, the modified compound of each of the above positive electrode active materials can be a doping modification and / or a surface coating modification to the positive electrode active material.

[0108] In some embodiments, the positive electrode film layer can further optionally include a positive electrode conductive agent. The present application does not have a particular limitation on the type of the positive electrode conductive agent, and as an example, the positive electrode conductive agent includes at least one of super P, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage content of the positive electrode conductive agent is ≤ 5% based on the total mass of the positive electrode film layer.

[0109] In some embodiments, the positive electrode film layer can further optionally include a positive electrode binder. The present application does not have a particular limitation on the type of the positive electrode binder, and as an example, the positive electrode binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic resin. In some embodiments, the mass percentage content of the positive electrode binder is ≤ 5% based on the total mass of the positive electrode film layer.

[0110] In some embodiments, the positive electrode current collector can adopt a metal foil or a composite current collector. As an example of the metal foil, an aluminum foil can be adopted. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material can include at least one of aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. As an example, the polymer material base layer can include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0111] The positive electrode film layer is generally formed by coating a positive electrode slurry on a positive electrode current collector, drying, and cold pressing. The positive electrode slurry is generally formed by dispersing a positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent and stirring uniformly. The solvent can be N-methyl pyrrolidone (NMP), but is not limited thereto.

[0112]

Negative electrode sheet

[0113] In some embodiments, the negative electrode tab includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and including a negative electrode active material. For example, the negative electrode current collector has two surfaces opposite in the thickness direction of itself, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0114] The negative electrode active material can employ a negative electrode active material for a secondary battery known in the art. As an example, the negative electrode active material can include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, a silicon-based film material, a tin-based film material, and lithium titanate. The silicon-based film material can include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material. The tin-based film material can include at least one of elemental tin, tin oxide, and tin alloy material.

[0115] In some embodiments, the negative electrode film layer can further optionally include a negative electrode conductive agent. The present application does not have a particular limitation on the kind of the negative electrode conductive agent, and as an example, the negative electrode conductive agent can include at least one of super P, conductive graphite, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber. In some embodiments, the mass percentage content of the negative electrode conductive agent is ≤ 5% based on the total mass of the negative electrode film layer.

[0116] In some embodiments, the negative electrode film layer can further optionally include a negative electrode binder. The present application does not have a particular limitation on the kind of the negative electrode binder, and as an example, the negative electrode binder can include at least one of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the mass percentage content of the negative electrode binder is ≤ 5% based on the total mass of the negative electrode film layer.

[0117] In some embodiments, the negative electrode film layer can further optionally include other auxiliary agents. As an example, the other auxiliary agents can include a thickening agent, for example, sodium carboxymethyl cellulose (CMC), PTC thermistor material, etc. In some embodiments, the mass percentage content of the other auxiliary agents is ≤ 2% based on the total mass of the negative electrode film layer.

[0118] In some embodiments, the negative current collector can employ a metal foil or a composite current collector. As an example of the metal foil, a copper foil can be employed. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material can include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer can include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0119] The negative film layer is generally formed by coating a negative slurry on a negative current collector, drying, and cold-pressing. The negative slurry is generally formed by dispersing a negative active material, an optional conductive agent, an optional binder, and other optional additives in a solvent and stirring uniformly. The solvent can be N-methyl pyrrolidone (NMP) or deionized water, but is not limited thereto.

[0120] The negative electrode sheet does not exclude other additional functional layers in addition to the negative film layer. For example, in some embodiments, the negative electrode sheet described herein further includes a conductive primer layer (e.g., composed of a conductive agent and a binder) interposed between the negative current collector and the negative film layer and disposed on the surface of the negative current collector. In some other embodiments, the negative electrode sheet described herein further includes a protective layer covering the surface of the negative film layer.

[0121]

Electrolyte

[0122] During charging and discharging of the secondary battery, active ions are inserted and de-inserted between the positive electrode sheet and the negative electrode sheet, and the electrolyte plays a role in conducting the active ions between the positive electrode sheet and the negative electrode sheet. The type of the electrolyte is not particularly limited in the present application and can be selected according to the actual needs.

[0123] The electrolyte includes an electrolyte salt and a solvent. The types of the electrolyte salt and the solvent are not particularly limited and can be selected according to the actual needs.

[0124] When the secondary battery of the present application is a lithium ion battery, as an example, the electrolyte salt can include, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro-oxalato-borate (LiDFOB), lithium difluoro-oxalato-borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluoro-dioxalato-phosphate (LiDFOP), and lithium tetrafluoro-oxalato-phosphate (LiTFOP).

[0125] When the secondary battery of the present application is a sodium-ion battery, as an example, the electrolyte salt can include, but is not limited to, at least one of sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium bisfluorosulfonylimide (NaFSI), sodium bis-trifluoromethanesulfonylimide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluoro oxalate borate (NaDFOB), sodium bisoxalate borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluoro di-oxalate phosphate (NaDFOP), and sodium tetrafluoro oxalate phosphate (NaTFOP).

[0126] As an example, the solvent can include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0127] In some embodiments, the electrolyte solution can also optionally include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and / or an additive capable of improving certain performance of the battery, such as an additive capable of improving overcharge performance of the battery, an additive capable of improving high-temperature performance of the battery, an additive capable of improving low-temperature power performance of the battery, and / or the like.

[0128] In some embodiments, the positive electrode sheet, the separator, and the negative electrode sheet can be made into an electrode assembly through a roll-pressing process and / or a stacking process.

[0129] In some embodiments, the secondary battery can include an outer package. The outer package can be used to encapsulate the electrode assembly and the electrolyte solution described above.

[0130] In some embodiments, the outer package of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, and / or the like. The outer package of the secondary battery can also be a soft package, such as a pouch soft package. The soft package can be made of plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0131] The preparation method of the secondary battery of the present application is known. In some embodiments, the positive electrode sheet, the separator, the negative electrode sheet and the electrolyte can be assembled to form the secondary battery. As an example, the positive electrode sheet, the separator, the negative electrode sheet can be formed into an electrode assembly through a winding process and / or a stacking process, the electrode assembly is placed in an outer package, the electrolyte is injected after drying, and the secondary battery is obtained through processes such as vacuum packaging, standing, formation, shaping, etc.

[0132] In some embodiments of the present application, the secondary battery according to the present application can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0133] Electric device

[0134] A power consuming device includes the above-mentioned secondary battery. The power consuming device includes at least one of the secondary battery, the battery module or the battery pack of the present application. The secondary battery, the battery module or the battery pack can be used as a power source of the power consuming device, or can be used as an energy storage unit of the power consuming device. The power consuming device can be, but is not limited to, a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc.

[0135] Embodiment 1

[0136] (1) Preparation of amino-modified silicone polymer

[0137] ① 0.3 parts by mass of water was prepared into a solution with pH = 3 using acetic acid.

[0138] ② 3 parts by mass of KH-550 and 4.5 parts by mass of tetrahydrofuran were added to the acetic acid aqueous solution in ①, stirred uniformly and heated to 60°C, and condensed refluxed for 6h.

[0139] ③ After the reaction was completed, the solvent and water were removed by distillation under reduced pressure at 65°C to obtain a polysiloxane in the form of a viscous liquid.

[0140] ④ The prepared polysiloxane, 40 parts by mass of hydroxyl-terminated silicone rubber (number average molecular weight 100,000) and 60 parts by mass of methyl MQ resin (number average molecular weight 2000, M / Q value: 0.6) were dissolved in 40 parts by mass of xylene, and stirred in a reaction kettle at 110°C for 3h.

[0141] ⑤ A solution containing 1.5 parts by mass of BPO dissolved in 3.5 parts by mass of xylene was further added, and stirred for 1h to obtain an amino-modified silicone pressure-sensitive adhesive solution.

[0142] (2) Preparation of amino-modified inorganic filler

[0143] 1800 parts by mass of boehmite was placed in deionized water, stirred and dispersed uniformly, then 17 parts by mass of KH-550 was added, and after reaction at 60℃ for 30 minutes, the temperature was raised to 150℃, and the reaction was continued for 15 minutes. Then, the filterate was placed in an oven and dried at 110℃ for 4 hours. After grinding into powder, silane-modified boehmite was obtained.

[0144] (3) The amino-modified silicone pressure-sensitive adhesive solution obtained in step (1), the silane-modified boehmite obtained in step (2), 100 parts by mass of E-51, and 8 parts by mass of ethylenediamine curing agent were added to 2500 parts by mass of a mixed solvent (a solution of dimethylbenzene:n-butanol in a mass ratio of 7:3), and stirred uniformly to obtain a self-laminating slurry.

[0145] (4) The self-laminating slurry obtained in step (3) was coated on both sides of a 7μm PE base film by roll coating using a double-dispensing and double-receiving double-sided coating line, and finally dried (solvent condensation reflux for reuse) to form a coating. The coating speed was 100m / min, the coating thickness was 2μm, and a PET release film was used for winding to prevent the separator from sticking.

[0146] The silicon element content of the upper and lower surfaces of the coating was detected by EDS energy spectrum, and V1>V2.

[0147] Examples 2-5 and Comparative Examples 1-2

[0148] The experimental steps of Examples 2-5 and Comparative Examples 1-2 were basically the same as those of Example 1, except that the mass fractions of the coupling agent in step (1) and step (2) and the mass fractions of the hydroxyl-terminated silicone rubber and methyl MQ resin in step (1) were different, as shown in Table 1.

[0149] Table 1: Mass fraction of formula and coating speed

[0150]

[0151] Data analysis:

[0152] 1. Permeability test method: The permeability of the separator was tested using a digital Wang-type permeability tester.

[0153] 2. Heat shrinkage test method: Take a 15 cm * 15 cm block-shaped separator, mark it as MD along the coating running direction, and mark it as TD vertically. Draw two mutually perpendicular line segments in the MD and TD directions, with lengths L0 and T0. Place the sample flat between two A4 papers and put it in an oven at 150°C for 1 hour. After heating, remove the sample and test the lengths of the two line segments in the MD and TD directions after it returns to room temperature. The lengths are L1 and T1. The separator heat shrinkage calculation formula is as follows: MD% = (L0-L1) / L0*100%, TD% = (T0-T1) / T0*100%.

[0154] 3. Adhesion strength test method: First, fold the coated side against each other, then use A4 paper to clamp the coated film and send it into a plastic packaging machine, with a temperature of 100°C and a speed setting of 1. After the end, use a 2.5 cm x 30 cm tooling mold to cut the sample, and finally test it on a tensile testing machine at a speed of 50 mm / min, test three times and take the average value.

[0155] The test results are shown in Table 2:

[0156] Table 2

[0157]

[0158]

[0159] It can be found from Comparative Examples 1-5 that as the mass fraction of silicone increases, the adhesion performance increases, and finally remains unchanged, the heat resistance also improves to a certain extent, but the air permeability becomes worse and worse. This is because the enrichment degree of silicone pressure-sensitive adhesive in the upper layer is constantly rising, and the support is getting stronger, but too much adhesive will cause hole blocking, which will reduce the air permeability of the separator.

[0160] Comparative Example 1 and Comparative Example 1 can find that when the coating speed reaches 180 m / min, the slurry cannot be layered in time due to the too fast drying speed, and the silicone resin cannot be enriched in the upper layer, so the adhesion strength is greatly reduced.

[0161] Comparative Example 1 and Comparative Example 2, non-crosslinked separator without KH550 modification, although the adhesion performance is basically unchanged, but the heat resistance is obviously reduced. This is because the coating layer has no crosslinking point support, and the support to the base film is also reduced.

[0162] The above merely describes a specific implementation of the present application. Those skilled in the art can clearly understand the specific working processes of the system, modules and units described above for the convenience and brevity of description, and can refer to the corresponding processes in the foregoing method embodiments, which will not be described herein again. It should be understood that the protection scope of the present application is not limited to this, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements should be covered within the protection scope of the present application.

Claims

1. A battery separator, comprising a base film and a coating disposed on at least one surface of the base film, characterized in that, The coating is obtained by applying a slurry in one step. The slurry includes an amino-modified organosilicon polymer, an amino-modified inorganic filler, and an epoxy resin. The content of the amino-modified organosilicon polymer on the upper surface of the coating is denoted as V1, and the content on the lower surface of the coating is denoted as V2, where V1>V2. The surface energy of the amino-modified organosilicon polymer is lower than that of the epoxy resin. The amino-modified organosilicon polymer aggregates on the upper surface of the coating, and the epoxy resin aggregates on the lower surface of the coating. The diaphragm satisfies at least one of the following conditions (1) to (4): (1) The longitudinal thermal shrinkage rate of the diaphragm at 150 °C for 1 h is 0.80%~1.10%; (2) The transverse thermal shrinkage rate of the diaphragm at 150 °C for 1 h is 0.40%~0.60%; (3) The adhesive strength of the diaphragm is 50~70 N / m; (4) The air permeability of the diaphragm is 160~190 s / 100cc.

2. The battery separator according to claim 1, characterized in that, The amino-modified organosilicon polymer, the amino-modified inorganic filler, and the epoxy resin are bonded together in the coating through the reaction of amino and epoxy groups to form a three-dimensional network cross-linked structure.

3. The battery separator according to claim 1, characterized in that, The mass ratio of the amino-modified organosilicon polymer, the amino-modified inorganic filler, and the epoxy resin is (2~10):1800:(80~120); and / or, The amino-modified organosilicon polymer includes amino-modified organosilicon pressure-sensitive adhesive; The amino-modified inorganic filler includes at least one of amino-modified alumina, amino-modified boehmite, amino-modified magnesium hydroxide, amino-modified silica, amino-modified titanium dioxide, amino-modified zirconium oxide, amino-modified hydrotalcite, and amino-modified montmorillonite. The epoxy resin includes bisphenol A type epoxy resin, and the type of bisphenol A type epoxy resin includes at least one of E-20, E-21, E-42, E-44, E-51 and E-54.

4. The battery separator according to claim 1, characterized in that, The coating also includes a curing agent, which includes amine curing agents.

5. The battery separator according to claim 4, characterized in that, The amine curing agent includes at least one of aliphatic amines, modified alicyclic amine curing agents, cashew phenol modified aliphatic amine curing agents, and polyamide curing agents.

6. The battery separator according to claim 1, characterized in that, The thickness of the coating is 1~6 μm; The thickness of the upper surface of the coating is 0.1% to 20% of the total coating thickness, and the thickness of the lower surface of the coating is 0.1% to 20% of the total coating thickness.

7. A method for preparing a battery separator, characterized in that, Includes the following steps: To prepare the slurry, amino-modified organosilicon polymer, amino-modified inorganic filler, and epoxy resin are mixed in a solvent in a predetermined ratio. The slurry is applied to at least one surface of the base film to form a coating and then dried to obtain a battery separator.

8. The preparation method according to claim 7, characterized in that, In the preparation of the slurry, the solvent includes at least one selected from xylene, n-butanol, methyl isobutyl ketone, butanone, acetone, tetrahydrofuran, butyl acetate, and ethyl acetate; and / or, The slurry also includes a curing agent, and the mass ratio of the curing agent to the epoxy resin is (6~10):(60~120). And / or, The preparation method of the amino-modified organosilicon polymer in the formulation of the slurry includes: Materials containing coupling agents and solvents are mixed, the pH of the mixture is adjusted to 2-4, and the temperature of the mixture is raised to 40-80 °C. The mixture is then refluxed for 4-8 hours, followed by vacuum distillation at 50-80 °C to obtain a polysiloxane. The polysiloxane, organosilicon polymer, and solvent are mixed according to a preset ratio and reacted at 90-120 °C for 2-5 hours. A polymer initiator is then added, and the reaction is continued for 0.5-3 hours to obtain the amino-modified organosilicon polymer; and / or, The mass ratio of the polysiloxane to the organosilicon polymer is (2~8):(80~220); and / or, The preparation method of the amino-modified inorganic filler includes: Inorganic filler, coupling agent, and solvent are mixed according to a preset ratio, reacted at 40–70 °C for 20–50 min, and then reacted at 120–170 °C for 10–30 min to obtain the amino-modified inorganic filler; and / or, The coupling agent includes KH-550, and the mass ratio of the inorganic filler to the coupling agent is 1800:(15~20); and / or, In coating, the coating method includes roller coating or spray coating.

9. A secondary battery comprising the battery separator according to any one of claims 1-6 or the battery separator prepared by the preparation method according to any one of claims 7-8.

10. An electrical device comprising the secondary battery of claim 9.

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