A lithium-ion battery separator, its preparation method and lithium-ion battery

Abstract

This application discloses a lithium-ion battery separator, its preparation method, and a lithium-ion battery, belonging to the field of battery separator technology. The lithium-ion battery separator of this application comprises a base film and an organic-inorganic hybrid layer composited on one or both sides of the base film; the precursor slurry for preparing the organic-inorganic hybrid layer comprises hair-like organic-inorganic hybrid nanoparticles, a binder, and a dispersant, wherein the hair-like organic-inorganic hybrid nanoparticles comprise: (a) a nano-silica core modified with a double-bonded silane coupling agent; and (b) hair-like polymer brushes grafted onto the surface of the nano-silica core modified with a double-bonded silane coupling agent, the hair-like polymer brushes being formed by in-situ polymerization of hydroxyl-containing acrylate monomers and epoxy-containing acrylate monomers; the binder comprises poly(butyl acrylate) and a combination of poly(butyl acrylate) and sodium carboxymethyl cellulose. The lithium-ion battery separator of this application can maintain good dimensional stability, electrolyte wettability, and ionic conductivity at high temperatures, effectively improving the cycle performance and rate performance of lithium-ion batteries.

Description

Technical Field

[0001] This application belongs to the field of battery separator technology, and specifically discloses a lithium-ion battery separator, its preparation method and lithium-ion battery. Background Technology

[0002] Lithium-ion batteries, with their advantages of high energy density, long cycle life, and low self-discharge rate, have become the core power source for electric vehicles and energy storage systems. As a key component of lithium-ion batteries, the performance of the battery separator directly affects the battery's safety, rate performance, and cycle life. However, traditional commercial battery separators mostly use PP, PE, and PP / PE composite membranes, which generally suffer from poor electrolyte wettability and severe high-temperature thermal shrinkage, significantly hindering the safe application of lithium metal batteries. Therefore, it is necessary to improve the performance of PP and / or PE battery separators.

[0003] Currently, methods for coating organic-inorganic core-shell composite coatings onto diaphragm surfaces to improve diaphragm performance have been disclosed in related fields. For example, prior art published in CN 103035866 A discloses a core-shell composite coating with silica as the core and acrylate-based polymer as the shell, achieving optimized improvements in coating uniformity and electrolyte adsorption capacity.

[0004] However, existing organic-inorganic core-shell composite coatings generally have shortcomings. For example, the fully encapsulated core-shell structure easily weakens the rigid support and heat resistance of inorganic particles, making it difficult to suppress the high-temperature thermal shrinkage of the composite separator. Furthermore, physically encapsulated shells still have problems such as weak interfacial bonding, poor mechanical strength and heat resistance, and the coating is prone to swelling and peeling. They cannot effectively solve the problems of insufficient electrolyte wettability and large high-temperature shrinkage, making it difficult to meet the requirements of high-safety and long-cycle batteries. Summary of the Invention

[0005] This application discloses a lithium-ion battery separator, its preparation method, and a lithium-ion battery, aiming to overcome the technical problems of insufficient electrolyte wettability and large high-temperature shrinkage in existing organic-inorganic core-shell composite coatings.

[0006] To achieve the above objectives, the technical solution provided in this application is as follows: The first aspect of this application provides a lithium-ion battery separator, which comprises a polyolefin-based membrane and an organic-inorganic hybrid layer composited on one or both sides of the polyolefin-based membrane. The precursor slurry for preparing the organic-inorganic hybrid layer comprises hair-like organic-inorganic hybrid nanoparticles, a binder, and a dispersant, wherein the hair-like organic-inorganic hybrid nanoparticles comprise: (a) A nano-silica core modified with a double-bonded silane coupling agent; and, (b) A hair-like polymer brush grafted onto the surface of the nano-silica core modified with a double-bonded silane coupling agent, the hair-like polymer brush being formed by in-situ polymerization of a hydroxyl-containing acrylate monomer and an epoxy-containing acrylate monomer. The adhesive comprises poly(butyl acrylate) and a combination of poly(butyl acrylate) and sodium carboxymethyl cellulose.

[0007] According to the preferred disclosure of the first aspect, the hydroxy acrylate monomer is selected from one of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl acrylate.

[0008] According to the preferred disclosure of the first aspect, the epoxy-containing acrylate monomer is selected from glycidyl methacrylate and glycidyl acrylate.

[0009] According to the preferred disclosure of the first aspect, the double-bonded silane coupling agent is selected from one of γ-methacryloyloxypropyltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane.

[0010] According to a preferred disclosure of the first aspect, the dispersant is selected from one of ammonium polyacrylate, polyethylene glycol, polyvinylpyrrolidone, and triethanolamine.

[0011] According to the preferred disclosure of the first aspect, the average particle size of the nano-silica core is 100~800nm, and the specific surface area is 50~300m². 2 / g.

[0012] The second aspect of this application also discloses a method for preparing the lithium-ion battery separator described above, which includes the following steps: Under an inert atmosphere, nano-silica and a silane coupling agent containing double bonds are thermally reacted in a dispersion solvent to obtain nano-silica modified with a silane coupling agent containing double bonds. The modified nano-silica containing double-bonded silane coupling agent, hydroxyl-containing acrylate monomers, and epoxy-containing acrylate monomers were subjected to a thermal polymerization reaction in a reaction solvent containing an initiator. Subsequently, they were washed, centrifuged, and dried to obtain hair-like organic-inorganic hybrid nanoparticles. After dispersing the hair-like organic-inorganic hybrid nanoparticles in an ethanol / water mixed solution to prepare a hybrid nanoparticle dispersion, a binder and a dispersant are added to prepare a precursor slurry. The precursor slurry is laid on the surface of a polyolefin-based membrane, cured and dried to obtain the lithium-ion battery separator.

[0013] According to the preferred disclosure of the second aspect, the dispersing solvent is selected from toluene, ethanol, and N,N-dimethylformamide.

[0014] According to the preferred disclosure of the second aspect, the reaction solvent is selected from N,N-dimethylformamide, toluene, and ethanol.

[0015] According to the preferred disclosure of the second aspect, the initiator is selected from one of azobisisobutyronitrile, benzoyl peroxide, and potassium persulfate.

[0016] According to the preferred disclosure of the second aspect, when the nano-silica and the double-bonded silane coupling agent are thermally reacted in a dispersion solvent, the mass ratio of nano-silica to the double-bonded silane coupling agent is 1:(0.5~1:2), the reaction temperature is 70~90℃, and the reaction time is 12~20h.

[0017] According to the preferred disclosure of the second aspect, when the double-bonded silane coupling agent-modified nano-silica, hydroxyl-containing acrylate monomers, and epoxy-containing acrylate monomers are subjected to a thermal polymerization reaction in a reaction solvent containing an initiator, the mass ratio of the double-bonded silane coupling agent-modified nano-silica to the hydroxyl-containing acrylate monomers is 1:(0.5~1.5), the molar ratio of the hydroxyl-containing acrylate monomers to the epoxy-containing acrylate monomers is 1:(0.3~1), the amount of initiator is 0.5~3% of the total mass of the monomers, the reaction temperature is 60~80℃, and the reaction time is 12~20h.

[0018] According to the preferred disclosure of the second aspect, the precursor slurry comprises the following components by mass: Hybrid nanoparticle dispersion 85-95%; Dispersant 1~3%; Adhesive 4~10%; The hybrid nanoparticle dispersion has a solid content of 15-25%.

[0019] According to the preferred disclosure of the second aspect, the film-laying method includes spin coating, blade coating and dip coating.

[0020] According to the preferred disclosure of the second aspect, the curing and drying temperature is 40~80°C and the time is 10~30 min.

[0021] The third aspect of this application also discloses a lithium-ion battery comprising a positive electrode, a negative electrode, and the lithium-ion battery separator described in this application.

[0022] Compared with the prior art, the advantages or beneficial effects of this application include at least: This application utilizes hydroxyl-containing acrylate monomers and epoxy-containing acrylate monomers to construct a polymer brush with a hair-like grafted structure and multiple active functional groups on the surface of nano-silica modified with a double-bonded silane coupling agent, thereby constructing core-shell structured organic-inorganic hybrid nanoparticles. The hair-like organic-inorganic hybrid nanoparticles, along with binders and dispersants, are then coated onto the surface of a polyolefin-based membrane to prepare a coated diaphragm. Firstly, the hair-like polymer brush layer has an outwardly extending configuration, which allows the open pore structure to fully utilize the heat resistance and rigid support of the nano-silica, while simultaneously forming a continuous nanoscale transition interface, effectively reducing phase separation and local defects. Firstly, the coating suppresses high-temperature thermal shrinkage of the separator at the structural level, giving the coated separator excellent high-temperature dimensional stability. Secondly, the multi-functionalized polymer brush layer not only significantly improves electrolyte wettability and ion transport efficiency through the synergistic effect between active functional groups, but also significantly improves the dispersion stability of nanoparticles in the precursor slurry through self-crosslinking to construct chemical anchoring interfaces. At the same time, it enhances the interfacial bonding force with binders and polyolefin-based films, greatly improving the uniformity and structural integrity of the nanoparticle coating. As a result, the coated separator can maintain good dimensional stability, electrolyte wettability, and ionic conductivity at high temperatures, effectively improving the cycle performance and rate performance of lithium-ion batteries. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 Synthetic route diagram for preparing hair-like organic-inorganic hybrid nanoparticles for this application; Figure 2 The SiO2, SiO2@KH570, and SiO2@P(HEA-) provided in this application co -GMA) and SiO2@P(AA- co FT-IR spectrum of -AN); Figure 3 HEA, GMA, and P(HEA-) provided for this application co -GMA) copolymers and AA, AN, P(AA- co FT-IR spectrum of the -AN) copolymer; Figure 4 The SiO2, SiO2@KH570, and SiO2@P(HEA-) provided in this application co -GMA) and SiO2@P(AA- coThermogravimetric analysis curve of -AN); Figure 5 The PE / SiO2 and PE / SiO2@P(HEA-) provided in this application co -GMA) and PE / SiO2@P(HEA- co SEM image of GMA-CMC; Figure 6 Dynamic light scattering diagrams of SiO2, SiO2@P(AA-co-AN) and SiO2@P(HEA-co-GMA) provided in this application; Figure 7 The PE / SiO2 and PE / SiO2@P(AA-) provided in this application co -AN), PE / SiO2@P(HEA- co -GMA) and PE / SiO2@P(HEA- co -GMA)-CMC air permeability analysis diagram; Figure 8 The PE / SiO2 and PE / SiO2@P(AA-) provided in this application co -AN), PE / SiO2@P(HEA- co -GMA) and PE / SiO2@P(HEA- co Analysis of wetting properties of GMA-CMC electrolyte; Figure 9 The PE / SiO2 and PE / SiO2@P(AA-) provided in this application co -AN), PE / SiO2@P(HEA- co -GMA) and PE / SiO2@P(HEA- co Analysis diagram of the heat shrinkage properties of GMA-CMC; Figure 10 The PE / SiO2 and PE / SiO2@P(AA-) provided in this application co -AN), PE / SiO2@P(HEA- co -GMA) and PE / SiO2@P(HEA- co Electrochemical performance diagram of GMA-CMC. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort are within the scope of protection of this application.

[0026] In the descriptions related to this application, the term "and / or" is used to describe the relationship between related objects, indicating the existence of three relationships. For example, A and / or B can represent: A existing alone, B existing alone, and A and B existing simultaneously. Here, A and B can be singular or plural; the symbol " / " means "or".

[0027] In the descriptions related to this application, the term "at least one" refers to one or more, and "multiple" refers to two or more; the term "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of A, B, or C" or "at least one of A, B, and C" can mean any one of A, B, and C, or A+B, or A+C, or B+C, or A+B+C, where A, B, and C can be single or multiple.

[0028] In the description of this application, the order of the serial numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be specifically determined by its function and internal logic, and does not constitute any limitation on the execution process of this embodiment.

[0029] In the description of this application, the numerical range should be understood to specifically disclose each intermediate value between the upper and lower limits of the range. Any intermediate value within a stated range, as well as any other stated value or each smaller range between intermediate values ​​within a stated range, are also included in this embodiment, and the upper and lower limits of the smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise stated, the technical / scientific terms used in this application have the meanings commonly understood by one of ordinary skill in the art. While this application describes only preferred materials and methods, similar or equivalent methods and materials may be used in specific embodiments or test cases. All references to this application are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this application shall prevail.

[0031] To address the shortcomings of existing organic-inorganic core-shell composite coatings in effectively solving the problems of insufficient electrolyte wettability and large high-temperature shrinkage, a first aspect of this application provides a lithium-ion battery separator. This lithium-ion battery separator comprises a polyolefin base film and an organic-inorganic hybrid layer composited on one or both sides of the polyolefin base film. The precursor slurry for preparing the organic-inorganic hybrid layer comprises hair-like organic-inorganic hybrid nanoparticles, a binder, and a dispersant. The hair-like organic-inorganic hybrid nanoparticles comprise: (a) a nano-silica core modified with a double-bonded silane coupling agent; and (b) hair-like polymer brushes grafted onto the surface of the nano-silica core modified with the double-bonded silane coupling agent. The hair-like polymer brushes are formed by in-situ polymerization of hydroxyl-containing acrylate monomers and epoxy-containing acrylate monomers. The binder comprises poly(butyl acrylate) and a combination of poly(butyl acrylate) and sodium carboxymethyl cellulose.

[0032] It should be noted that the polyolefin-based membrane described in this application refers to a functional polymer membrane specifically designed for lithium-ion battery separators. Specifically, it is a functional membrane prepared using polyolefin resin as the core raw material, supplemented with functional modifying components, and processed through a specific molding path. It allows lithium-ion conduction while blocking electron passage. Options include polypropylene (PP) separators, polyethylene (PE) separators, and polypropylene / polyethylene (PP / PE) composite separators. In this application, polyethylene (PE) separators are used as an example to illustrate the general effects of the organic-inorganic hybrid coating and do not constitute any limitation on the scope of protection. PP separators and PP / PE composite separators are also applicable to the technical solutions of this application, and will not be illustrated individually.

[0033] It should be noted that the hair-like organic-inorganic hybrid nanoparticles described in this application refer to hair-like polymer brushes that are grafted onto the surface of nano-silica, thereby forming organic-inorganic hybrid nanoparticles with a core-shell structure. The hair-like polymer brush layer structure can construct an open pore structure, which allows the heat resistance and rigid support of nano-silica to be fully utilized.

[0034] Based on the above description, this application utilizes hydroxyl-containing acrylate monomers and epoxy-containing acrylate monomers to construct a polymer brush with a hair-like grafted structure and multiple active functional groups on the surface of nano-silica modified with a double-bonded silane coupling agent in situ, thereby constructing core-shell structured organic-inorganic hybrid nanoparticles. The hair-like organic-inorganic hybrid nanoparticles, along with binders and dispersants, are then coated onto the surface of a polyolefin-based membrane to prepare a coated diaphragm. Firstly, the hair-like polymer brush layer has an outwardly extending configuration, which allows the open pore structure to fully utilize the heat resistance and rigid support of the nano-silica, while simultaneously forming a continuous nanoscale transition interface, effectively reducing phase separation and localized phase transitions. The defects are addressed by firstly, suppressing high-temperature thermal shrinkage of the separator at the structural level, thus enabling the coated separator to possess excellent high-temperature dimensional stability; secondly, the multi-functionalized polymer brush layer can not only significantly improve electrolyte wettability and ion transport efficiency through the synergistic effect between active functional groups, but also significantly improve the dispersion stability of nanoparticles in the precursor slurry through self-crosslinking to construct chemical anchoring interfaces. At the same time, it can also enhance the interfacial bonding force with binders and polyolefin-based films, greatly improving the uniformity and structural integrity of the nanoparticle coating. As a result, the composite separator can maintain good dimensional stability, electrolyte wettability, and ionic conductivity at high temperatures, effectively improving the cycle performance and rate performance of lithium-ion batteries.

[0035] It should be noted that this application does not limit the coating thickness of the organic-inorganic hybrid layer, as long as a coated separator that meets the requirements of lithium-ion batteries and has a good modification effect is obtained. In this embodiment, the preferred coating thickness is approximately 2 μm, and the overall loading is 1.7 mg / cm³. 2 .

[0036] It should be noted that the hydroxyl-containing acrylate monomers described in this application refer to acrylate monomers containing an active hydroxyl group (-HO) in their molecular structure, preferably one of 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA), and 2-hydroxypropyl acrylate (HPA). In this application, 2-hydroxyethyl acrylate (HEA) is used as a representative example to illustrate the general effects of this type of monomer structure and does not constitute any limitation on the scope of protection. 2-hydroxyethyl methacrylate (HEMA) and 2-hydroxypropyl acrylate (HPA) are also applicable to the technical solutions of this application, and will not be illustrated individually here.

[0037] It should be noted that the epoxy-containing acrylate monomers described in this application refer to acrylate monomers containing epoxy groups in their molecular structure, preferably one of glycidyl methacrylate (GMA) and glycidyl acrylate (GA). In this application, glycidyl methacrylate (GMA) is used as a representative example to illustrate the general effects of this type of monomer structure and does not constitute any limitation on the scope of protection. 2-Hydroxypropyl acrylate (HPA) is also applicable to the technical solutions of this application, and will not be illustrated individually here.

[0038] It should be noted that the double-bond silane coupling agent described in this application refers to a silane coupling agent containing carbon-carbon double bonds (C=C) in its molecular structure, preferably one of γ-methacryloyloxypropyltrimethoxysilane (KH570), vinyltrimethoxysilane (KH171), and vinyltriethoxysilane (KH151).

[0039] It should be noted that the dispersant described in this application is preferably one of ammonium polyacrylate, polyethylene glycol, polyvinylpyrrolidone, and triethanolamine. The embodiments in this application use ammonium polyacrylate as a representative example for illustration, aiming to demonstrate the modification effect of the hair-like organic-inorganic hybrid nanoparticles of this application, and do not constitute any limitation on the scope of protection. The polyethylene glycol, polyvinylpyrrolidone, or triethanolamine mentioned above are also applicable to the technical solutions of this application, and will not be illustrated individually here.

[0040] It should be noted that the average particle size of the nano-silica core described in this application is 100~800nm, and the specific surface area is 50~300m². 2 / g. In the embodiments of this application, the average particle size is 300~500nm, and the specific surface area is approximately 200m². 2 The example of / g nano-silica is provided only because the particle size and specific surface area are close to the middle value of the preferred range, which can clearly verify the modification effect of the hair-like organic-inorganic hybrid nanoparticles of this application. It does not constitute any limitation on the scope of protection, and this application will not provide examples one by one.

[0041] The second aspect of this application provides a method for preparing the lithium-ion battery separator described in this application, preferably comprising the following steps: Under an inert atmosphere, nano-silica and a silane coupling agent containing double bonds are thermally reacted in a dispersion solvent to obtain nano-silica modified with a silane coupling agent containing double bonds. The modified nano-silica containing double-bonded silane coupling agent, hydroxyl-containing acrylate monomers, and epoxy-containing acrylate monomers were subjected to a thermal polymerization reaction in a reaction solvent containing an initiator. Subsequently, they were washed, centrifuged, and dried to obtain hair-like organic-inorganic hybrid nanoparticles. After dispersing the hair-like organic-inorganic hybrid nanoparticles in an ethanol / water mixed solution to prepare a hybrid nanoparticle dispersion, a binder and a dispersant are added to prepare a precursor slurry. The precursor slurry is laid on the surface of a polyolefin-based membrane, cured and dried to obtain the lithium-ion battery separator.

[0042] In possible disclosed examples, the dispersing solvent described in this application is selected from one of toluene, ethanol, N,N-dimethylformamide (DMF), etc.; the reaction solvent is selected from one of N,N-dimethylformamide (DMF), toluene, ethanol, etc.; and the initiator is selected from one of azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), potassium persulfate, etc.

[0043] In possible disclosed examples, when the nano-silica and the double-bonded silane coupling agent undergo a thermal reaction in a dispersion solvent, the preferred mass ratio of nano-silica to the double-bonded silane coupling agent is 1:(0.5~1:2), the preferred reaction temperature is 70~90℃, and the reaction time is 12~20h. Specifically, this application uses a mass ratio of nano-silica to the double-bonded silane coupling agent of 1:1.2 as an example, and conducts a thermal reaction at 80℃ for 16h. This is intended to verify the surface modification effect of the double-bonded silane coupling agent on nano-silica and does not constitute any limitation on the scope of protection. Further examples are not provided in this application.

[0044] In possible public examples, when the double-bonded silane coupling agent-modified nano-silica, hydroxyl-containing acrylate monomers, and epoxy- or cyano-containing acrylate monomers are thermally polymerized in a reaction solvent containing an initiator, the mass ratio of the double-bonded silane coupling agent-modified nano-silica to the hydroxyl-containing acrylate monomers is preferably 1:(0.5~1.5), the molar ratio of the hydroxyl-containing acrylate monomers to the epoxy-containing acrylate monomers is preferably 1:(0.3~1), the amount of initiator is preferably 0.5~3% of the total mass of the monomers, the reaction temperature is preferably 60~80℃, and the reaction time is preferably 12~20h. In this embodiment, the mass ratio of nano-silica modified with double-bonded silane coupling agent to hydroxyl-containing acrylate monomer is 1:0.7, the molar ratio of hydroxyl-containing acrylate monomer to epoxy-containing or cyano-containing acrylate monomer is 1:0.5, and the amount of initiator is preferably 1.3% of the total monomer mass. The thermal polymerization reaction is carried out at 70°C for 16 hours. This is intended to illustrate the improvement effect of the hair-like organic-inorganic hybrid nanoparticles of this application and does not constitute any limitation on the scope of protection. This application will not provide further examples.

[0045] In possible examples of disclosure, the precursor slurry described in this application preferably comprises the following components by mass: Hybrid nanoparticle dispersion 85-95%; Dispersant 1~3%; Adhesive 4~10%; The hybrid nanoparticle dispersion has a solid content of 15-25%.

[0046] It should be noted that the embodiments of this application are illustrated by: (1) 90% hybrid nanoparticle dispersion, 8% binder and 2% dispersant; (2) 88% hybrid nanoparticle dispersion, 10% binder and 2% dispersant, respectively, in order to illustrate the modification effect of the hair-like organic-inorganic hybrid nanoparticles of this application on polyolefin-based films, and do not constitute any limitation on the scope of protection. This application will not provide examples for each of them.

[0047] In possible disclosed examples, the film-laying method described in this application includes spin coating, blade coating, and dip coating. The embodiments in this application use spin coating as an example only to illustrate the technical effect of using hair-like organic-inorganic hybrid nanoparticles to coat modified polyolefin-based films, and do not constitute any limitation on the scope of protection. This application will not provide further examples of each process.

[0048] In possible disclosed examples, the curing and drying temperature described in this application is preferably 40~80℃, and the time is preferably 10~30min. The example in this application, drying at 50℃ for 20min, is intended to verify the feasibility of the curing conditions for the organic-inorganic hybrid coating of this application and does not constitute any limitation on the scope of protection; therefore, this application will not provide further examples.

[0049] A third aspect of the embodiments of this application also provides a lithium-ion battery, which includes a positive electrode, a negative electrode and a separator, wherein the separator is the lithium-ion battery separator described in this application.

[0050] The technical solution of this application will be further described below with reference to specific embodiments.

[0051] Example 1 This example provides a lithium-ion battery separator (PE / SiO2@P(HEA-) co The specific preparation process for GMA is as follows: Step 1 - Preparation of hair-like organic-inorganic hybrid nanoparticles; the synthetic route is as follows: Figure 1 As shown: 3.0g of nano-SiO2 microspheres (average particle size approximately 300~500nm, specific surface area approximately 200m²) were used. 2 / g) was dispersed in 35mL of toluene solvent and sonicated for 1h to ensure complete dispersion. Nitrogen gas was introduced into the dispersion system for 0.5h to ensure complete deoxygenation. The temperature was raised to 80℃, and 3.5mL (1.045g / mL) of γ-methacryloyloxypropyltrimethoxysilane (KH570) was added under stirring. The reaction was carried out for 16h. After the reaction was completed, the mixture was cooled to room temperature, washed thoroughly with anhydrous ethanol, centrifuged 3 times, and dried under vacuum at 40℃ for 12h to obtain nano-silica (SiO2@KH570) modified with double bond silane coupling agent. 3.0 g SiO2@KH570 was dispersed in 27 mL of N,N-dimethylformamide (DMF) and sonicated for 1 h. Then, 2.2 g (21.97 mmol) of 2-hydroxyethyl acrylate (HEA) and 1.6 g (11.26 mmol) of glycidyl methacrylate (GMA) were added and stirred until homogeneous. Nitrogen gas was bubbled through the solution for 0.5 h to remove oxygen. The solution was then heated to 70 °C, and 0.05 g (0.30 mmol) of azobisisobutyronitrile (AIBN) was added under stirring. The reaction was carried out for 16 h. After the reaction was completed, the solution was cooled to room temperature, washed with ethanol, and centrifuged three times to collect the hair-like organic-inorganic hybrid nanoparticles (SiO2@P(HEA- co -GMA)).

[0052] Step 2 - Preparation of precursor slurry The hair-like organic-inorganic hybrid nanoparticles (SiO2@P(HEA- co -GMA)) was redispersed in a 50wt.% aqueous ethanol solution at a solid content of 20% to obtain a hybrid nanoparticle dispersion. The hybrid nanoparticle dispersion, ammonium polyacrylate and poly(butyl acrylate) were then mixed at a mass ratio of 90:2:8 to prepare a precursor slurry.

[0053] Step 3 - Coating the diaphragm The precursor slurry was spin-coated onto one side surface of the PE separator (approximately 2 μm thick), and then dried in an oven at 50°C for 20 minutes to obtain the lithium-ion battery separator (PE / SiO2@P(HEA- co -GMA)).

[0054] Example 2 This example provides a lithium-ion battery separator (PE / SiO2@P(HEA-) co The specific preparation process for GMA-CMC is as follows: Step 1 - Preparation of hair-like organic-inorganic hybrid nanoparticles; the synthetic route is as follows: Figure 1 As shown: 3.0g of nano-SiO2 microspheres (average particle size approximately 300~500nm, specific surface area approximately 200m²) were used.2 The γ-methacryloxypropyltrimethoxysilane (KH570) was dispersed in 35 mL of toluene solvent and sonicated for 1 h to ensure complete dispersion. Nitrogen gas was then introduced into the dispersion system for 0.5 h to remove oxygen. The temperature was raised to 80 °C, and 3.5 mL (1.045 g / mL) of γ-methacryloxypropyltrimethoxysilane (KH570) was added under stirring. The reaction was carried out for 16 h. After the reaction was completed, the mixture was cooled to room temperature, washed thoroughly with anhydrous ethanol, centrifuged three times, and then vacuum dried at 40 °C for 12 h to obtain nano-silica modified with double-bonded silane coupling agent (SiO2@KH570). 3.0 g SiO2@KH570 was dispersed in 27 mL of N,N-dimethylformamide (DMF) and sonicated for 1 h. Then, 2.2 g (21.97 mmol) of 2-hydroxyethyl acrylate (HEA) and 1.6 g (11.26 mmol) of glycidyl methacrylate (GMA) were added and stirred until homogeneous. Nitrogen gas was bubbled through the solution for 0.5 h to remove oxygen. The solution was then heated to 70 °C, and 0.05 g (0.30 mmol) of azobisisobutyronitrile (AIBN) was added under stirring. The reaction was carried out for 16 h. After the reaction was completed, the solution was cooled to room temperature, washed with ethanol, and centrifuged three times to collect the hair-like organic-inorganic hybrid nanoparticles (SiO2@P(HEA- co -GMA)).

[0055] Step 2 - Preparation of precursor slurry The hair-like organic-inorganic hybrid nanoparticles (SiO2@P(HEA- co -GMA)) was redispersed in a 50wt.% ethanol aqueous solution at a solid content of 20% to obtain a hybrid nanoparticle dispersion. The hybrid nanoparticle dispersion, ammonium polyacrylate, poly(butyl acrylate) and sodium carboxymethyl cellulose (CMC) were then mixed in a mass ratio of 88:2:5:5 to prepare a precursor slurry.

[0056] Step 3 - Coating the diaphragm The precursor slurry was spin-coated onto one side surface of the PE separator (approximately 2 μm thick), and then dried in an oven at 50°C for 20 min to obtain the lithium-ion battery separator (PE / SiO2@P(HEA- co -GMA)-CMC).

[0057] Comparative Example 1 This example provides a SiO2-coated separator (PE / SiO2), which is prepared as follows: 3.0g of nano-SiO2 microspheres (average particle size approximately 300~500nm, specific surface area approximately 200m²) were used. 2 / g) was directly dispersed in water with a solid content of 20%, and then ammonium polyacrylate and poly(acrylate-butyl acrylate) were added at a mass ratio of 90:2:8 for SiO2 aqueous dispersion, dispersant and binder to prepare a precursor slurry. The precursor slurry was spin-coated onto one side surface of the PE membrane (approximately 2 μm thick), and then dried in an oven at 50°C for 20 min to obtain a SiO2-coated membrane (PE / SiO2).

[0058] Comparative Example 2 This example provides a lithium-ion battery separator (PE / SiO2@P(AA-) co The specific preparation process for -AN)) is as follows: Step 1 - Preparation of organic-inorganic hybrid nanoparticles 3.0g of nano-SiO2 microspheres (average particle size approximately 300~500nm, specific surface area approximately 200m²) were used. 2 The γ-methacryloxypropyltrimethoxysilane (KH570) was dispersed in 35 mL of toluene solvent and sonicated for 1 h to ensure complete dispersion. Nitrogen gas was then introduced into the dispersion system for 0.5 h to remove oxygen. The temperature was raised to 80 °C, and 3.5 mL (1.045 g / mL) of γ-methacryloxypropyltrimethoxysilane (KH570) was added under stirring. The reaction was carried out for 16 h. After the reaction was completed, the mixture was cooled to room temperature, washed thoroughly with anhydrous ethanol, centrifuged three times, and then vacuum dried at 40 °C for 12 h to obtain nano-silica modified with double-bonded silane coupling agent (SiO2@KH570). 3.0 g of SiO2@KH570 was dispersed in 27 mL of N,N-dimethylformamide (DMF) and sonicated for 1 h. Then, 3.31 g (45.95 mmol) of acrylic acid (AA) and 0.49 g (9.19 mmol) of acrylonitrile (AN) were added and stirred until homogeneous. Nitrogen gas was bubbled through the solution for 0.5 h to remove oxygen. The temperature was then raised to 70 °C, and 0.05 g (0.30 mmol) of azobisisobutyronitrile (AIBN) was added under stirring. The reaction was carried out for 16 h. After the reaction was completed, the mixture was cooled to room temperature, washed with ethanol, and centrifuged three times to collect the organic-inorganic hybrid nanoparticles (SiO2@P(AA- co -AN)).

[0059] Step 2 - Preparation of precursor slurry The organic-inorganic hybrid nanoparticles (SiO2@P(AA-) co -AN)) was redispersed in a 50wt.% ethanol aqueous solution at a solid content of about 20% to obtain a hybrid nanoparticle dispersion. The hybrid nanoparticle dispersion, ammonium polyacrylate dispersant and poly(butyl acrylate) binder were then mixed at a mass ratio of 90:2:8 to prepare a precursor slurry.

[0060] Step 3 - Coating the diaphragm The precursor slurry was spin-coated onto one side surface of the PE separator (approximately 2 μm thick), and then dried in an oven at 50°C for 20 min to obtain the lithium-ion battery separator (PE / SiO2@P(AA- co -AN)).

[0061] Test Example 1 This application provides SiO2, SiO2@KH570, and SiO2@P(HEA- co -GMA) and SiO2@P(AA- co The FT-IR spectrum of -AN) is as follows: Figure 2 As shown.

[0062] according to Figure 2 It can be seen that SiO2@P(HEA- co Compared to SiO2, SiO2@P(HEA-GMA) co -GMA) at 1730cm -1 A stretching vibration peak of the ester carbonyl group (C=O) appeared at 1640 cm⁻¹ (corresponding to the ester structure of HEA and GMA); -1 A stretching vibration peak of the C=C double bond was observed at 2850-2950 cm⁻¹, and its intensity was significantly weaker than that of the monomer, indicating that the double bond had undergone polymerization; -1 A saturated CH stretching vibration peak appeared within the range, consistent with the characteristic peak of SiO2@KH570, at 3400 cm⁻¹. -1 The broad peak at [location] is attributed to the hydroxyl (-OH) stretching vibration peak of the HEA monomer, corroborating the introduction of HEA. Simultaneously, the Si-O-Si stretching vibration peak of the SiO2 framework (1100 cm⁻¹) is also present. -1 The presence and broadening of the peak indicate that the structure of the nano-SiO2 microspheres was not destroyed during the grafting process, and that the peaks overlapped with the COC vibration peaks of the organic chains, proving that SiO2@P(HEA- co The successful preparation of (-GMA). Similarly, SiO2@P(AA- co Compared to SiO2, SiO2@P(AA-) co -AN) at 1718cm -1 A distinct C=O stretching vibration peak appeared at 1635 cm⁻¹ (corresponding to the carboxyl group structure in the AA monomer); -1 A stretching vibration peak of the C=C double bond was observed at 3200~3500 cm⁻¹, and its intensity was significantly weaker than that of the monomer, indicating that the double bond underwent a polymerization reaction; -1 The broad peak at this location is attributed to the stretching vibration of the hydroxyl (-OH) group of the AA unit, which also corroborates the presence of AA. Meanwhile, the Si-O-Si stretching vibration peak of the SiO2 framework (~1100 cm⁻¹) is also present.-1 The presence and broadening of the peak indicate that the structure of the nano-SiO2 microspheres was not destroyed during the grafting process, and that the peaks overlapped with the COC vibration peaks of the organic chains, proving that SiO2@P(AA-) co Successful preparation of -AN).

[0063] This application provides HEA, GMA, and P(HEA- co -GMA) copolymers and AA, AN, P(AA- co The FT-IR spectrum of the -AN) copolymer was obtained. Figure 3 As shown.

[0064] according to Figure 3 It can be seen that both HEA and GMA monomers have a concentration of 1640 cm⁻¹. -1 The region exhibits a strong C=C stretching vibration peak, while P(HEA-) co The intensity of this peak is significantly reduced in the GMA copolymer, while the 1720 cm⁻¹ peak is retained. -1 The ester carbonyl peak is located at [location missing], and the characteristic peak of the epoxy group unique to GMA monomer is 908~760 cm⁻¹. -1 The fact that some epoxy groups are still observable indicates that some epoxy groups were retained after polymerization, while SiO2@P(HEA- co -GMA) and P(HEA- co The infrared peak positions of the -GMA) copolymer are highly consistent, further confirming that the organic component grafted onto the SiO2 surface is P(HEA- co -GMA) copolymer. Similarly, AA monomer at 1720cm -1 The AN monomer exhibits a strong C=O stretching vibration peak at 2228 cm⁻¹. -1 The region exhibits a strong -C≡N stretching vibration peak, while P(AA-) co The 1720 cm⁻¹ of the AN) copolymer was retained simultaneously. -1 The carboxyl peak and 2228 cm⁻¹ -1 The cyano peak, and the characteristic peak of the C=C double bond in both (1640 cm⁻¹) -1 The strength of both decreased significantly, indicating that AA and AN underwent a copolymerization reaction and were grafted onto the SiO2 surface.

[0065] Test Example 2 This application provides SiO2, SiO2@KH570, and SiO2@P(HEA- co -GMA) and SiO2@P(AA- co The thermogravimetric analysis curve of -AN) yielded the following results: Figure 4 As shown.

[0066] according to Figure 4As can be seen, the SiO2 microspheres exhibit virtually no thermal weight loss within the temperature range of 0–800℃, demonstrating the excellent intrinsic thermal stability of SiO2. SiO2@KH570 begins to lose weight slowly after 300℃, with a total weight loss of approximately 1% at 800℃. This weight loss corresponds to the thermal decomposition of KH570 on the SiO2 microsphere surface, proving that KH570 has been successfully grafted onto the SiO2 surface, providing double bond active sites for subsequent free radical polymerization. SiO2@P(HEA- co Significant weight loss was observed in the P(HEA-) grafted onto the surface of the SiO2 microspheres in the 300–500 °C range, with a total weight loss of approximately 3.5% up to 800 °C. This weight loss originated from P(HEA-) grafted onto the surface of the SiO2 microspheres. co After deducting the weight loss contribution of KH570 from the thermal decomposition of the HEA-GMA copolymer, P(HEA-GMA) can be estimated. co The grafting amount of the P(HEA-) copolymer was approximately 2.5%, quantitatively confirming that P(HEA-) co Successful grafting of α-GMA copolymer onto the surface of SiO2 microspheres. SiO2@P(AA- co The weight loss of AA- is more significant in the 300~500℃ range, with a total weight loss of approximately 4.5% at 800℃. After deducting the weight loss contribution of KH570, the weight loss of AA- can be estimated. co The grafting amount of the -AN copolymer is approximately 3.5%.

[0067] Test Example 3 This application provides PE / SiO2, PE / SiO2@P(HEA- co -GMA) and PE / SiO2@P(HEA- co SEM image of -GMA-CMC, the result is Figure 5 As shown.

[0068] according to Figure 5 It can be seen that SiO2, SiO2@P(HEA- co -GMA) and SiO2@P(HEA- co -GMA)-CMC both formed a composite layer structure on the surface of the PE base film, and SiO2 and SiO2@P(HEA- co Both SiO2@P(HEA-GMA) exhibit highly regular spherical structures with clear boundaries and no obvious aggregation, indicating that the SiO2@P(HEA-GMA) in this application possesses a high degree of regularity. co -GMA) can be used in composite modified PE-based films to maintain good sphericity and dispersibility.

[0069] Test Example 4 This application provides SiO2, SiO2@P(AA- co -AN) and SiO2@P(HEA- co Dynamic light scattering diagram of GMA.

[0070] according to Figure 6 It can be seen that the average particle size of the nano-SiO2 microspheres is 485.7±3.1 nm, and the SiO2@P(AA- co The average particle size of SiO2@P(HEA-) increased to 497.3±2.5 nm. co The average particle size of -GMA increases to 530.0 ± 3.5 nm. Therefore, the SiO2@P(HEA- co -GMA) can form a structure comparable to SiO2@P(AA- co -AN) A more porous composite layer structure.

[0071] Test Example 5 This application tested the above-mentioned PE / SiO2 and PE / SiO2@P(AA-) respectively. co -AN), PE / SiO2@P(HEA- co -GMA) and PE / SiO2@P(HEA- co The air permeability, electrolyte wettability, thermal shrinkage rate, and electrochemical properties of GMA-CMC are as follows: 5.1 Breathability The above PE / SiO2, PE / SiO2@KH570, and PE / SiO2@P(AA-) were respectively tested. co -AN), PE / SiO2@P(HEA- co -GMA) and PE / SiO2@P(HEA- co -GMA)-CMC was tested for breathability, and the results were: Figure 7 As shown.

[0072] according to Figure 7 It can be seen that the air permeability of PE / SiO2 is 184s / 100cc; the air permeability of PE / SiO2@KH570 is 220s / 100cc; and the air permeability of PE / SiO2@P(AA- co The air permeability of PE / SiO2@P(HEA-) is 234s / 100cc; co -GMA) air permeability is 214.28s / 100cc; PE / SiO2@P(HEA- co The air permeability of SiO2@P(HEA-GMA)-CMC is 290.34 s / 100 cc, indicating that SiO2@P(HEA-GMA)-CMC has good permeability. co -GMA) compared to SiO2@P(AA- co The relatively low density of the SiO2@P(HEA-AN) composite layer indicates that the SiO2@P(HEA-AN) composite layer has a relatively low density. co- The GMA composite layer creates an open pore structure; at the same time, the use of a combination binder of poly(butyl acrylate) and sodium carboxymethyl cellulose reduces air permeability.

[0073] 5.2 Electrolyte wettability The above PE / SiO2 and PE / SiO2@P(AA-) were respectively tested. co -AN), PE / SiO2@P(HEA- co -GMA) and PE / SiO2@P(HEA- co Electrolyte wettability tests were conducted using GMA-CMC, and the results were as follows: Figure 8 As shown.

[0074] according to Figure 8 It can be seen that the wetting width of PE / SiO2 at 120s is approximately 60mm, and the wetting width of PE / SiO2@P(AA- co -AN) had a wetting width of approximately 19.7 mm at 120 s, significantly lower than that of PE / SiO2@P(HEA- co -GMA) 84mm and PE / SiO2@P(HEA- co The 76mm of GMA-CMC indicates that the present application significantly improves the electrolyte wetting performance by forming a hair-like polymer brush through in-situ polymerization of hydroxyl-containing acrylate monomers and epoxy-containing acrylate monomers on the surface of the nano-silica core modified with double-bonded silane coupling agent. Furthermore, the use of a combination binder of poly(butyl acrylate) and sodium carboxymethyl cellulose can further improve the electrolyte wetting performance.

[0075] 5.3 Thermal shrinkage rate The above PE / SiO2 and PE / SiO2@P(AA-) were respectively tested. co -AN), PE / SiO2@P(HEA- co -GMA) and PE / SiO2@P(HEA- co The heat shrinkage performance of GMA-CMC was tested, and the results were as follows: Figure 9 As shown.

[0076] according to Figure 9 It can be seen that the length shrinkage rate of PE / SiO2 is approximately 25%, and the width shrinkage rate is approximately 23.3%; PE / SiO2@P(AA- co The length shrinkage rate of PE / SiO2@P(HEA-) is approximately 26.7%, and the width shrinkage rate is approximately 26%; co The length shrinkage rate of PE / SiO2@P(HEA-GMA) is approximately 4.8%, and the width shrinkage rate is approximately 3%; coThe length shrinkage rate of GMA-CMC is about 4.5%, and the width shrinkage rate is about 3%, indicating that the heat resistance of the hair-like polymer brush formed by in-situ polymerization of 2-hydroxyethyl acrylate and glycidyl methacrylate on the surface of the nano-silica core modified with double bond silane coupling agent is significantly improved. Furthermore, the heat resistance can be further improved by using a combination binder of poly(butyl acrylate) and sodium carboxymethyl cellulose.

[0077] 5.4 Electrochemical performance The above PE / SiO2 and PE / SiO2@P(AA-) were respectively tested. co -AN), PE / SiO2@P(HEA- co -GMA) and PE / SiO2@P(HEA- co Electrochemical performance was tested using GMA-CMC. Specifically, CR2032 coin cells were assembled using lithium iron phosphate cathode, lithium foil anode, electrolyte, and separator. The separators used were Celgard separator, PE / SiO2 separator, and PE / SiO2@P(HEA- co -GMA) separator and PE / SiO2@P(HEA- co -GMA)-CMC diaphragm; the electrolyte is prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) in a mass ratio of 3:5:2.

[0078] (1) Constant current charge-discharge test: After the above-mentioned CR2032 coin cells were left to stand at room temperature overnight, a cycle test was performed. Specifically, the coin cells were fully charged and discharged at room temperature at rates of 0.33C, 1C, 2C and 5C respectively (charge-discharge voltage window is 4~2.8V). Among them, the long cycle test of 1C requires the battery to be charged and discharged at a constant current rate of 0.33C for 5 cycles before starting the 1C charge-discharge cycle; the test procedure of 2C is the same, first charge and discharge at a rate of 0.33C for 5 cycles, and then perform the 2C charge-discharge cycle.

[0079] (2) Rate Cycling Test: After the CR2032 coin cells were left to stand at room temperature overnight, rate performance tests were conducted. The test charge / discharge voltage window was set to 4~2.8V, and constant current charge / discharge was performed within this voltage range. The charging rates were sequentially set to 0.1C, 0.2C, 0.4C, 0.6C, 0.8C, 1C, and 2C. After 5 cycles at each rate, the rate was restored to 0.1C and 5 cycles were performed again to evaluate the battery's capacity recovery capability after experiencing high-rate charge / discharge. During the test, the charging capacity, charging time, voltage curve, and battery surface temperature changes were recorded to analyze the capacity retention, charge / discharge efficiency, polarization characteristics, and thermal behavior at different rates. The results are as follows: Figure 10 As shown.

[0080] according to Figure 10 It is evident that after 80 cycles at 0.33C, the capacity of PE / SiO2 rapidly decreases to approximately 60 mAh / g, with an ICE of only 63.85%; PE / SiO2@P(AA- co -AN) after 80 cycles at 0.33C, the capacity rapidly decreased to approximately 60 mAh / g, with an ICE of only 63.85%; PE / SiO2@P(HEA- co -GMA) maintained a capacity of 128mAh / g after 80 cycles at 0.33C, with an ICE efficiency of 88.5% in the first cycle; PE / SiO2@P(HEA- co The GMA-CMC retains a capacity of 130mAh / g after 80 cycles at 0.33C, with an ICE efficiency of 87.2% in the first cycle.

[0081] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0082] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A lithium-ion battery separator, characterized by, It comprises a polyolefin-based membrane and an organic-inorganic hybrid layer composited on one or both sides of the polyolefin-based membrane; The precursor slurry for preparing the organic-inorganic hybrid layer comprises hair-like organic-inorganic hybrid nanoparticles, a binder, and a dispersant, wherein the hair-like organic-inorganic hybrid nanoparticles comprise: (a) A nano-silica core modified with a double-bonded silane coupling agent; and, (b) A hair-like polymer brush grafted onto the surface of the nano-silica core modified with a double-bonded silane coupling agent, the hair-like polymer brush being formed by in-situ polymerization of a hydroxyl-containing acrylate monomer and an epoxy-containing acrylate monomer. The adhesive comprises poly(butyl acrylate) and a combination of poly(butyl acrylate) and sodium carboxymethyl cellulose.

2. The lithium-ion battery separator of claim 1, wherein, The hydroxyl-containing acrylate monomer is selected from one of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl acrylate. And / or, the epoxy-containing acrylate monomer is selected from glycidyl methacrylate and glycidyl acrylate.

3. The lithium-ion battery separator according to claim 1, characterized in that, The double-bond silane coupling agent is selected from one of γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane; And / or, the dispersant is selected from one of ammonium polyacrylate, polyethylene glycol, polyvinylpyrrolidone, and triethanolamine.

4. The lithium-ion battery separator of claim 1, wherein, The average particle size of the nano-silicon oxide core is 100-800 nm, and the specific surface area is 50-300 m 2 / g.

5. A method for producing the separator for lithium ion batteries according to any one of claims 1 to 4, characterized by, Includes the following steps: Under an inert atmosphere, nano-silica and a silane coupling agent containing double bonds are thermally reacted in a dispersion solvent to obtain nano-silica modified with a silane coupling agent containing double bonds. The modified nano-silica containing double-bonded silane coupling agent, hydroxyl-containing acrylate monomers, and epoxy-containing acrylate monomers were subjected to a thermal polymerization reaction in a reaction solvent containing an initiator. Subsequently, they were washed, centrifuged, and dried to obtain hair-like organic-inorganic hybrid nanoparticles. After dispersing the hair-like organic-inorganic hybrid nanoparticles in an ethanol / water mixed solution to prepare a hybrid nanoparticle dispersion, a binder and a dispersant are added to prepare a precursor slurry. The precursor slurry is laid on the surface of a polyolefin-based membrane, cured and dried to obtain the lithium-ion battery separator.

6. The method of claim 5 wherein the step of forming the first and second layers comprises the step of: The dispersion solvent is selected from toluene, ethanol, and N,N-dimethylformamide; ​ And / or, the reaction solvent is selected from one of N,N-dimethylformamide, toluene, and ethanol; And / or, the initiator is selected from one of azobisisobutyronitrile, benzoyl peroxide, and potassium persulfate.

7. The method of claim 5 wherein the step of forming the first and second layers comprises the step of: When the nano-silica and the double-bonded silane coupling agent are thermally reacted in a dispersion solvent, the mass ratio of nano-silica to the double-bonded silane coupling agent is 1:(0.5~1:2), the reaction temperature is 70~90℃, and the reaction time is 12~20h. ​ And / or, when the double-bonded silane coupling agent-modified nano-silica, hydroxyl-containing acrylate monomers, and epoxy-containing acrylate monomers are subjected to thermal polymerization in a reaction solvent containing an initiator, the mass ratio of the double-bonded silane coupling agent-modified nano-silica to the hydroxyl-containing acrylate monomers is 1:(0.5~1.5), the molar ratio of the hydroxyl-containing acrylate monomers to the epoxy-containing acrylate monomers is 1:(0.3~1), the amount of initiator is 0.5~3% of the total mass of the monomers, the reaction temperature is 60~80℃, and the reaction time is 12~20h.

8. The method of claim 5 wherein the step of forming the first and second layers comprises the step of: The precursor slurry comprises the following components by mass: ​ Hybrid nanoparticle dispersion 85-95%; Dispersant 1~3%; Adhesive 4~10%; The hybrid nanoparticle dispersion has a solid content of 15-25%.

9. The method of claim 5 wherein the step of forming the first and second layers comprises the step of: The film-laying method includes spin coating, blade coating, and dip coating; ​ And / or, the curing and drying temperature is 40~80℃, and the time is 10~30min.

10. A lithium ion battery comprising a positive electrode, a negative electrode, and a separator, characterized in that, The separator is the lithium-ion battery separator according to any one of claims 1 to 4.

Images