Breakdown-resistant lithium-ion solid-state battery separator, preparation method thereof and lithium-ion battery

Abstract

The present application relates to a kind of breakdown-resistant lithium ion solid-state battery separator and its preparation method, lithium ion battery.The breakdown-resistant lithium ion solid-state battery separator has layered structure, including base film layer and the self-repairing polymer layer and composite coating sequentially arranged on the outer surface of the base film layer, the thickness of the self-repairing polymer layer is 1-5 μm, the composite coating includes nanoparticle reinforced polymer and interface enhancer.The breakdown-resistant lithium ion solid-state battery separator provided by the present application can effectively improve the breakdown-resistant performance, self-repairing ability and overall electrochemical performance of lithium ion battery separator, and can significantly improve the safety and performance of lithium ion battery, especially in high energy density and high power application has obvious advantage.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery materials technology, and in particular to a breakdown-resistant lithium-ion solid-state battery separator, its preparation method, and a lithium-ion battery. Background Technology

[0002] Lithium-ion batteries have become an indispensable energy solution in modern electronic devices and electric vehicles. However, traditional liquid electrolyte lithium-ion batteries have safety hazards, such as leakage, thermal runaway, and short circuits. Solid-state batteries have become a research hotspot due to their high safety, high energy density, and long cycle life. The battery separator plays a crucial role in solid-state batteries, its main function being to separate the positive and negative electrodes, allowing lithium ions to pass through while hindering electron transport. It is a thin film with a microporous structure that prevents the battery from overheating.

[0003] In lithium metal batteries, lithium dendrites form during charging and discharging. These dendrites can puncture the separator, causing an internal short circuit. The formation of lithium dendrites is related to the high reactivity of lithium metal, uneven deposition, and interfacial reactions between the electrolyte and lithium metal. Micropores, cracks, or other defects may exist in the separator during manufacturing; these defects can become pathways for internal short circuits during battery operation, leading to separator breakdown.

[0004] As battery usage time and charge / discharge cycles increase, the separator gradually ages. During battery aging, the separator may be subjected to various factors such as chemical corrosion, thermal aging, and mechanical stress. These factors may cause structural changes, material degradation, or accumulation of microscopic damage in the separator material, which may reduce the separator's mechanical strength, making it more susceptible to rupture or perforation under internal battery pressure or lithium dendrite growth, thus increasing the risk of separator breakdown. After separator breakdown, a short circuit occurs between the positive and negative electrodes, triggering a gas reaction inside the lithium battery, generating a large amount of heat and gas, which may lead to battery overheating, fire, or even explosion, affecting the overall performance and safety of the battery.

[0005] Therefore, it is necessary to provide a breakdown-resistant separator for lithium-ion solid-state batteries. Summary of the Invention

[0006] In the prior art, as the battery usage time increases and the number of charge-discharge cycles increases, the separator will gradually age, thereby increasing the risk of separator breakdown and affecting the overall performance and safety of the battery. Therefore, it is necessary to provide a breakdown-resistant lithium-ion solid-state battery separator and its preparation method, and a lithium-ion battery to solve the above problems.

[0007] In a first aspect, the present invention provides a breakdown-resistant lithium-ion solid-state battery separator having a layered structure, including a base film layer and a self-healing polymer layer and a composite coating sequentially disposed on the outer surface of the base film layer, wherein the thickness of the self-healing polymer layer is 1-5 μm, and the composite coating includes a nanoparticle-reinforced polymer and an interface reinforcing agent.

[0008] In one implementation, the base film layer comprises a matrix material, an inorganic filler, and an ionic conductor. The matrix material comprises any one of polyvinylidene fluoride, polyetherimide, or polyethylene oxide. The inorganic filler comprises any one of alumina, zirconium oxide, and lithium sulfide. The ionic conductor comprises any one of polyethylene oxide, lithium bis(trifluoromethanesulfonate)imide, lithium sulfide, lithium lanthanum zirconium oxide, and lithium fluoride. The thickness of the base film layer is 5-20 μm.

[0009] In one implementation, the self-healing polymer includes any one of polythiol, polymethyl methacrylate, and polyacrylate gel.

[0010] In one implementation, the nanoparticle-reinforced polymer comprises a polymer matrix and nanoparticles, wherein the polymer matrix is ​​polyvinylidene fluoride or polyethyleneimine, and the nanoparticles comprise any one of graphene, carbon nanotubes, and silver nanoparticles.

[0011] In one implementation, the mass ratio of the polymer matrix to the nanoparticles in the nanoparticle-reinforced polymer is between 80:20 and 95:5.

[0012] In one implementation, the interface enhancer is a silane coupling agent or a titanate coupling agent.

[0013] In one implementation, the thickness of the composite coating is 2-5 μm.

[0014] In one implementation, the composite coating further includes a second network polymer that forms a self-healing interpenetrating network structure with the self-healing polymer. The second network polymer includes any one of poly(hydroxyethyl methacrylate), polyurethane prepolymer, polyvinyl alcohol, and isocyanate-terminated polymers. The mass fraction of the second network polymer in the composite coating is 2 to 10 wt%.

[0015] Secondly, the present invention also provides a method for preparing a breakdown-resistant lithium-ion solid-state battery separator, which is used in the breakdown-resistant lithium-ion solid-state battery separator described in the present invention, and includes the following specific steps:

[0016] S1. The polymer matrix and inorganic filler are dispersed in an organic solvent in a certain proportion, and the mixture is ultrasonically / stirred until uniform. The film is then formed on a plate by casting to obtain the base film layer.

[0017] S2. Dissolve the self-healing polymer in a solvent to prepare a coating or colloid, and uniformly coat it onto the outer surface of the base film layer using a coating method to obtain the self-healing polymer layer.

[0018] S3. Mix the polymer matrix with nanoparticles, disperse them by ultrasonic treatment or ball milling to make the nanoparticles uniformly distributed, add an interface enhancer to mix and obtain a mixed slurry, and coat the mixed slurry on the outer surface of the self-healing polymer layer.

[0019] S4. The coated membrane material is subjected to heat treatment at a temperature of 120-180℃ for 30-60 minutes to obtain the breakdown-resistant lithium-ion solid-state battery separator.

[0020] Thirdly, the present invention also provides a lithium-ion battery comprising the breakdown-resistant lithium-ion solid-state battery separator described in any of the preceding claims.

[0021] Beneficial Effects: The breakdown-resistant lithium-ion solid-state battery separator provided by this invention not only improves the durability of the membrane through a self-healing polymer layer, but also automatically repairs itself when micro-damage occurs, increasing battery safety. The composite coating integrates anti-breakdown function and interface enhancement technology, further enhancing the overall stability and safety of the membrane. By setting a layered structure, the advantages of the composite coating and the self-healing polymer layer are fully utilized, effectively improving the breakdown resistance, self-healing ability, and overall electrochemical performance of the lithium-ion battery separator. This significantly enhances the safety and performance of lithium-ion batteries, especially in high-energy-density and high-power applications. Attached Figure Description

[0022] Figure 1 This is a flowchart of the steps involved in preparing the breakdown-resistant lithium-ion solid-state battery separator provided by the present invention.

[0023] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Furthermore, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., described below refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the technical features involved in the various embodiments of the invention can be combined with each other as long as they do not conflict with each other.

[0025] This invention provides a breakdown-resistant lithium-ion solid-state battery separator with a layered structure, including a base film layer and a self-healing polymer layer and a composite coating sequentially disposed on the outer surface of the base film layer. The thickness of the self-healing polymer layer is 1-5 μm, and the composite coating includes a nanoparticle-reinforced polymer and an interface enhancer. The breakdown-resistant lithium-ion solid-state battery separator provides basic mechanical strength and structural stability through the base film layer; the self-healing polymer layer enables self-repair when subjected to mechanical damage such as cracks or pinholes, effectively preventing short circuits or battery failure due to damage to the separator, thus improving battery life and safety; and the composite coating enhances the separator's breakdown resistance and interface stability.

[0026] Specifically, the base film layer comprises a matrix material, an inorganic filler, and an ion conductor. The matrix material comprises any one of polyvinylidene fluoride (PVDF), polyetherimide (PEI), or polyethylene oxide (PEO). The inorganic filler comprises any one of alumina (Al2O3), zirconium oxide, and lithium sulfide. The thickness of the base film layer is 5-20 μm. The ion conductor comprises any one of polyethylene oxide (PEO), lithium bis(trifluoromethanesulfonate)imide (LiTFSI), lithium sulfide (Li3PS4), lithium lanthanum zirconium oxide (LLZO), and lithium fluoride (LiF).

[0027] The matrix material provides the structural strength and mechanical stability of the separator, while the inorganic filler enhances the thermal stability, mechanical strength, and electrolyte permeability of the separator. The ionic conductor strengthens ionic conductivity and improves the overall battery performance. Through comprehensive utilization, the base film layer enables the solid-state battery separator to not only provide excellent isolation but also sufficient ionic conductivity and mechanical strength, while simultaneously improving battery safety.

[0028] Specifically, the self-healing polymer includes any one of polythiol, polymethyl methacrylate, and polyacrylate gel. This self-healing polymer possesses self-healing capabilities, which can significantly improve the durability and safety of the membrane.

[0029] Specifically, in the composite coating, the nanoparticle-reinforced polymer comprises a polymer matrix and nanoparticles. The polymer matrix is ​​polyvinylidene fluoride (PVDF) or polyethyleneimine (PEI), and the nanoparticles include any one of graphene, carbon nanotubes (CNTs), and silver nanoparticles. The nanoparticles significantly improve the mechanical strength and wear resistance of the separator, preventing it from cracking or wearing down due to mechanical stress during use. The nanoparticles also exhibit high thermal stability, improving the separator's stability under high-temperature conditions and preventing deformation or failure due to temperature changes. Furthermore, the combination of the nanoparticles and the polymer matrix optimizes the electrochemical performance of the separator, improves lithium-ion conductivity, and thus enhances the overall performance of the battery.

[0030] In the nanoparticle-reinforced polymer, the mass ratio of the polymer matrix to the nanoparticles is between 80:20 and 95:5. The interface reinforcing agent is a silane coupling agent or a titanate coupling agent. Preferably, the thickness of the composite coating is 2-5 μm. The preferred silane coupling agent is KH-550. The nanoparticle-reinforced polymer enhances the mechanical strength and conductivity of the membrane, while the silane coupling agent or titanate coupling agent improves the interfacial stability of the composite coating, reduces interfacial resistance, and enhances overall performance.

[0031] Furthermore, the composite coating further includes a second network polymer that forms a self-healing interpenetrating network (IPN) structure with the self-healing polymer. The second network polymer comprises any one of poly(hydroxyethyl methacrylate), polyurethane prepolymer (PU), polyvinyl alcohol (PVA), and isocyanate-terminated polymers, with a mass fraction of 2-10 wt% in the composite coating. Specifically, poly(hydroxyethyl methacrylate) (PHEMA) can polymerize and crosslink into a network; polyurethane prepolymer (PU) contains -NH- and -C=O, and can form hydrogen bonds with thiols; polyvinyl alcohol (PVA) is water-soluble, can form a hydrogen-bonded network, and has good interfacial affinity with polythiols; and the isocyanate-terminated polymer can undergo an addition reaction with SH to form crosslinks, exhibiting chemically coupled self-healing function.

[0032] The addition of a second network polymer creates a self-healing interpenetrating network structure, significantly enhancing the material's self-healing ability and enabling the membrane to repair itself more quickly and effectively when damaged. Furthermore, the introduction of the second network polymer improves the structural stability of the composite coating, preventing separation or detachment due to external stress or environmental changes. The second network polymer also improves the interfacial bonding between the composite coating and the self-healing polymer layer, ensuring tight adhesion between layers and enhancing the overall performance of the membrane.

[0033] See also Figure 1 , Figure 1 This is a flowchart of the steps involved in preparing the breakdown-resistant lithium-ion solid-state battery separator provided by the present invention.

[0034] This invention also provides a method for preparing a breakdown-resistant lithium-ion solid-state battery separator, which includes the following specific steps:

[0035] S1. The polymer matrix and inorganic filler are dispersed in an organic solvent in a certain proportion, and the mixture is ultrasonically / stirred until uniform. The film is then formed on a plate by casting to obtain the base film layer.

[0036] S2. Dissolve the self-healing polymer in a solvent to prepare a coating or colloid, and uniformly coat it onto the outer surface of the base film layer using a coating method to obtain the self-healing polymer layer.

[0037] S3. Mix the polymer matrix with nanoparticles, disperse them by ultrasonic treatment or ball milling to make the nanoparticles uniformly distributed, add an interface enhancer to mix and obtain a mixed slurry, and coat the mixed slurry on the outer surface of the self-healing polymer layer.

[0038] S4. The coated membrane material is subjected to heat treatment at a temperature of 120-180℃ for 30-60 minutes to obtain the breakdown-resistant lithium-ion solid-state battery separator.

[0039] When the composite coating includes a second network polymer that forms a self-healing interpenetrating network (IPN) with the self-healing polymer, step S3 further includes: adding the self-healing polymer to the composite coating slurry; after the composite coating contacts the self-healing layer, a portion of the self-healing polymer penetrates into the self-healing polymer layer; heating to 70-100°C triggers the cross-linking and molding of the self-healing interpenetrating network structure to form the final composite coating.

[0040] The layered structure of this invention allows for more precise control over the thickness, composition, and function of each layer, thereby optimizing the performance of each layer. Furthermore, during the fabrication of the layered structure, the characteristics of each layer can be precisely controlled through coating or heat treatment of each layer, and the unique properties of each material can be fully utilized. The composite coating and self-healing polymer layer can selectively leverage their respective advantages to achieve synergistic material functionality. Compared to mixing materials into a slurry, the layered structure provided by this invention offers greater adjustability and optimization, contributing to maximizing the functionality of each layer.

[0041] Example 1

[0042] Material selection:

[0043] Base film layer: Polyvinylidene fluoride (PVDF) is selected as the matrix material, alumina (Al2O3) as the inorganic filler, and lithium sulfide (Li3PS4) as the ion conductor.

[0044] Self-healing polymer layer: polythiol is selected.

[0045] Composite coating: PVDF is selected as the polymer matrix, graphene as the nanoparticles, and silane coupling agent (KH-550) as the interface reinforcing agent.

[0046] Preparation steps:

[0047] S1. Disperse PVDF and alumina in dimethylacetamide (DMAc) solvent at a mass ratio of 90:10, sonicate for 30 minutes, and stir until homogeneous. Add lithium sulfide (Li3PS4) and continue stirring for 1 hour to ensure homogeneity. Cast the film on a plate using a casting method, controlling the film thickness to 15 μm, and dry to obtain the base film layer.

[0048] S2. Preparation of the self-healing polymer layer: Polythiol was dissolved in toluene solvent to prepare a 5% coating. The coating was uniformly applied to the outer surface of the base film using a coating method, with the coating thickness controlled at 2 μm. After drying, the self-healing polymer layer was obtained.

[0049] S3. Preparation of the composite coating: PVDF and graphene were mixed at a mass ratio of 90:10 and ultrasonically treated for 30 minutes to ensure uniform distribution of nanoparticles. Silane coupling agent (KH-550) was added and stirred until homogeneous. The mixed slurry was uniformly coated onto the outer surface of the self-healing polymer layer using a coating method, with the coating thickness controlled at 3 μm. The composite coating was then dried to obtain the final product.

[0050] S4. Heat treatment: The coated membrane material is subjected to heat treatment at a temperature of 150°C for 45 minutes to obtain the final breakdown-resistant lithium-ion solid-state battery separator.

[0051] Example 2

[0052] Base film: PVDF+Al2O3+Li3PS4, thickness is 15μm;

[0053] Self-healing polymer layer: polymethyl methacrylate (PMMA), 2μm thick;

[0054] Composite coating: PVDF + graphene + KH-550, with a thickness of 3μm.

[0055] The specific preparation process is the same as in Example 1, and will not be repeated here.

[0056] Example 3

[0057] Base film: PVDF+Al2O3+Li3PS4, thickness is 15μm;

[0058] Self-healing polymer layer: polythiol, 2μm thick;

[0059] Composite coating: PEI + graphene + titanate coupling agent, with a thickness of 3μm.

[0060] The specific preparation process is the same as in Example 1, and will not be repeated here.

[0061] Example 4

[0062] Base film: PVDF+Al2O3+Li3PS4, thickness is 15μm;

[0063] Self-healing polymer layer: polyacrylate gel, 2μm thick;

[0064] Composite coating: PEI + graphene + titanate coupling agent, with a thickness of 3μm.

[0065] The specific preparation process is the same as in Example 1, and will not be repeated here.

[0066] Example 5

[0067] Base film layer: PEO + alumina (Al2O3) + lithium fluoride (LiF), with a thickness of 15μm;

[0068] Self-healing polymer layer: polythiol, 2μm thick;

[0069] Composite coating: PEO + carbon nanotubes + titanate coupling agent, with a thickness of 3μm;

[0070] The specific preparation process is the same as in Example 1, and will not be repeated here.

[0071] Example 6

[0072] Base film: PVDF + zirconium oxide (ZrO2) + lithium sulfide (Li3PS4), with a thickness of 15μm;

[0073] Self-healing polymer layer: polythiol, 2μm thick;

[0074] Composite coating: PVDF + graphene + silane coupling agent (KH-550), with a thickness of 3μm;

[0075] The specific preparation process is the same as in Example 1, and will not be repeated here.

[0076] Example 7

[0077] Base film layer: polyethylene oxide (PEO) + aluminum oxide (Al2O3) + lithium sulfide (Li3PS4), with a thickness of 15μm;

[0078] Self-healing polymer layer: polyacrylate gel, 2μm thick;

[0079] Composite coating: PEO + carbon nanotubes + silane coupling agent (KH-550), with a thickness of 3μm;

[0080] The specific preparation process is the same as in Example 1, and will not be repeated here.

[0081] Example 8

[0082] Base film layer: PEI + aluminum oxide (Al2O3) + LiTFSI, with a thickness of 15μm;

[0083] Self-healing polymer layer: polymethyl methacrylate (PMMA), 15μm thick;

[0084] Composite coating: PEI + graphene + titanate coupling agent, with a thickness of 15μm;

[0085] The specific preparation process is the same as in Example 1, and will not be repeated here.

[0086] Example 9

[0087] Base film layer: PVDF + alumina (Al2O3) + lithium sulfide (Li3PS4), with a thickness of 15μm;

[0088] Self-healing polymer layer: polymethyl methacrylate (PMMA), 2μm thick;

[0089] Composite coating: PVDF + graphene + KH-550 + polyurethane prepolymer (PU), with a thickness of 3μm;

[0090] The specific preparation process is the same as in Example 1, and will not be repeated here.

[0091] Example 10

[0092] Base film layer: PEO + alumina (Al2O3) + lithium fluoride (LiF), with a thickness of 15μm;

[0093] Self-healing polymer layer: polythiol, 2μm thick;

[0094] Composite coating: PEO + carbon nanotubes + titanate coupling agent + polyhydroxyethyl methacrylate, with a thickness of 3μm;

[0095] The specific preparation process is the same as in Example 1, and will not be repeated here.

[0096] Comparative Example 1

[0097] Base film layer: PVDF + alumina (Al2O3) + lithium sulfide (Li3PS4), with a thickness of 15μm;

[0098] Composite coating: PVDF + graphene + KH-550, with a thickness of 3μm;

[0099] Comparative Example 2

[0100] Base film layer: PVDF + alumina (Al2O3) + lithium sulfide (Li3PS4), with a thickness of 15μm;

[0101] Self-healing polymer layer: polythiol, 2μm thick;

[0102] Comparative Example 3

[0103] Base film layer: PEO + alumina (Al2O3) + lithium fluoride (LiF), with a thickness of 15μm;

[0104] Self-healing polymer layer: polythiol, 2μm thick;

[0105] Composite coating: PEO + silane coupling agent (KH-550), with a thickness of 3μm.

[0106] Comparative Example 4

[0107] Base film layer: PEI + alumina (Al2O3) + lithium sulfide (Li3PS4), with a thickness of 15μm;

[0108] Self-healing polymer layer: polyacrylate gel, 2μm thick;

[0109] Composite coating: PEI + graphene, with a thickness of 3μm.

[0110] The breakdown-resistant lithium-ion solid-state battery separators provided in the above embodiments and comparative examples were subjected to electrical performance, mechanical performance, and cycle charge-discharge tests.

[0111] 1. Electrical performance testing

[0112] Breakdown voltage test: The breakdown voltage of the diaphragm material is tested using standard voltage breakdown testing equipment according to ISO 18079. The test procedure involves applying a gradually increasing voltage across the sample until the diaphragm breaks down. The breakdown voltage is recorded.

[0113] Ionic conductivity testing: Electrodes were applied across the sample using an electrochemical impedance spectroscopy (EIS) instrument, and the impedance was measured. Ionic conductivity was obtained through Nyquist plot analysis. The test results are shown in Table 1.

[0114] Table 1. Breakdown Voltage Test Results

[0115]

[0116] As shown in Table 1, the breakdown voltage of the lithium-ion solid-state battery separator of the present invention is significantly higher than that of traditional polypropylene and polyethylene separators. The separators of the embodiments exhibit higher breakdown voltage and ionic conductivity, indicating that the design of these embodiments improves the conductivity and breakdown resistance of the separator, enabling it to withstand higher voltages and greatly reducing the risk of battery short circuits and fires. Among them, the data of Examples 9 and 10 are optimal, indicating that the addition of the second network polymer to the composite coating can play a certain promoting role.

[0117] 2. Mechanical performance testing

[0118] Tensile strength test: Tensile tests were performed using an electronic universal testing machine according to ASTM D882 standard. Standard-sized diaphragm samples (10 mm x 50 mm) were prepared, and the maximum tensile strength and elongation of the material were recorded.

[0119] Tear strength test: Tear strength was tested according to ASTM D1004 standard. Standard tear testing equipment was used to prepare standard tear samples, and the tear resistance of the diaphragm under external force was tested. The tear strength was recorded. The test results are shown in Table 2.

[0120] Table 2. Mechanical Performance Test Results

[0121]

[0122] As can be seen from the results in Table 2, the diaphragms in the embodiments provided by the present invention significantly outperform the comparative examples and conventional PP and PE diaphragms in terms of tensile strength, elongation, and tear strength. In particular, Example 9 exhibits excellent performance in tensile strength and elongation, attributed to its thickness and the excellent combination of the self-healing material, along with the addition of the second network polymer.

[0123] 3. Cyclic charge-discharge test

[0124] The separators corresponding to the examples and comparative examples were used as separators for lithium-ion solid-state batteries, and coin cells were prepared according to the following method:

[0125] Taking Example 1 as an example:

[0126] Cathode material: LiFePO4;

[0127] Anode material: graphite;

[0128] Electrolyte: LiPF6 solution;

[0129] Membrane: The PVDF+Al2O3+Li3PS4 membrane prepared in Example 1 has been treated with a self-healing layer and a composite coating.

[0130] Electrode preparation: LiFePO4 was mixed with a conductive agent (carbon black) and a binder (PVDF) in a certain proportion, coated onto aluminum foil, dried, and cut into round pieces to serve as the positive electrode. Graphite was mixed with a conductive agent and a binder in a certain proportion, coated onto copper foil, dried, and cut into round pieces to serve as the negative electrode.

[0131] Button cell assembly: Inside the glove box, place the separator on the negative electrode, add electrolyte, align the positive electrode with the separator, and press them together. Use a button cell packaging device to seal the battery, ensuring its airtightness.

[0132] Test equipment: The battery was tested using a battery testing system with multiple charge-discharge cycles. The battery charging voltage was set to 4.2V and the discharging voltage to 2.5V.

[0133] Cycle count: The test consisted of 500 charge-discharge cycles, with each cycle lasting 1 hour. The capacity retention and coulombic efficiency were recorded for each cycle.

[0134] The test results are shown in Table 3.

[0135] Table 3. Results of Cyclic Charge-Discharge Test

[0136]

[0137] The data in Table 3 shows that the materials in the examples exhibit good capacity retention, especially Examples 1, 6, 9, and 10, which all maintain a high capacity retention (over 90%) after 500 cycles. This demonstrates that the breakdown-resistant lithium-ion solid-state battery separator provided by this invention improves the battery's initial capacity, capacity retention, coulombic efficiency, and other performance characteristics, and effectively extends the battery's lifespan, enhancing its safety and stability. In particular, Examples 9 and 10 show the highest initial capacity, capacity retention, and coulombic efficiency, while the performance of the comparative examples and traditional PP and PE separators is significantly worse.

[0138] The breakdown-resistant lithium-ion solid-state battery separator in the embodiments, due to the introduction of a self-healing polymer layer and composite coating, effectively prevents short circuits and enhances the battery's breakdown resistance, ensuring battery safety during long-term use. The materials in the embodiments exhibit excellent electrochemical performance, significantly improving the capacity retention, cycle performance, and charge / discharge efficiency of lithium-ion batteries. Especially in high-energy-density and high-power applications, the separator material in the embodiments demonstrates significant advantages, meeting the needs and market trends of modern lithium-ion batteries, further demonstrating the superiority of the novel separator material provided by this invention in lithium-ion solid-state batteries.

[0139] This invention improves the breakdown resistance of the separator and reduces the risk of battery short circuits by providing a composite coating of nanoparticle-reinforced polymer and interface enhancer. The addition of a self-healing polymer layer allows for self-repair upon mechanical damage, extending the separator's lifespan and improving battery safety. The addition of a second network polymer to the composite coating forms a self-healing interpenetrating network structure, significantly enhancing the material's self-healing ability, enabling the separator to repair itself more quickly and effectively upon damage. Simultaneously, the use of materials with good ionic conductivity, such as polyethylene oxide (PEO) and lithium sulfide (Li3PS4), in the base film layer ensures efficient charge-discharge performance of the battery. Furthermore, by using appropriate matrix materials and inorganic fillers, the separator exhibits excellent mechanical strength and thermal stability, enabling stable operation at high temperatures. The breakdown-resistant lithium-ion solid-state battery separator provided by this invention can effectively improve the breakdown resistance, self-healing ability, and overall electrochemical performance of lithium-ion battery separators. It has excellent mechanical strength, conductivity, and thermal stability, ensuring that the separator can work effectively in high energy density and high power applications. It can significantly improve the safety and performance of lithium-ion batteries, especially showing obvious advantages in high energy density and high power applications.

[0140] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A breakdown-resistant lithium-ion solid-state battery separator, characterized in that, The material has a layered structure, including a base film layer and a self-healing polymer layer and a composite coating layer sequentially disposed on the outer surface of the base film layer. The thickness of the self-healing polymer layer is 1-5 μm. The composite coating layer includes a nanoparticle-reinforced polymer and an interface reinforcing agent. The composite coating layer also includes a second network polymer that forms a self-healing interpenetrating network structure with the self-healing polymer. The second network polymer includes any one of poly(hydroxyethyl methacrylate), polyurethane prepolymer, polyvinyl alcohol, and isocyanate-terminated polymers. The mass fraction of the second network polymer in the composite coating layer is 2-10 wt%.

2. The breakdown-resistant lithium-ion solid-state battery separator according to claim 1, characterized in that, The base film layer comprises a matrix material, an inorganic filler, and an ion conductor. The matrix material comprises any one of polyvinylidene fluoride, polyetherimide, or polyethylene oxide. The inorganic filler comprises any one of alumina, zirconium oxide, and lithium sulfide. The ion conductor comprises any one of polyethylene oxide, lithium bis(trifluoromethanesulfonate)imide, lithium sulfide, lithium lanthanum zirconium oxide, and lithium fluoride. The thickness of the base film layer is 5-20 μm.

3. The breakdown-resistant lithium-ion solid-state battery separator according to claim 1, characterized in that, The self-healing polymer includes any one of polythiol, polymethyl methacrylate, and polyacrylate gel.

4. The breakdown-resistant lithium-ion solid-state battery separator according to claim 1, characterized in that, The nanoparticle-reinforced polymer comprises a polymer matrix and nanoparticles. The polymer matrix is ​​polyvinylidene fluoride or polyethyleneimine, and the nanoparticles include any one of graphene, carbon nanotubes, and silver nanoparticles.

5. The breakdown-resistant lithium-ion solid-state battery separator according to claim 4, characterized in that, In the nanoparticle-reinforced polymer, the mass ratio of the polymer matrix to the nanoparticles is 80:20 to 95:

5.

6. The breakdown-resistant lithium-ion solid-state battery separator according to claim 1, characterized in that, The interface enhancer is a silane coupling agent or a titanate coupling agent.

7. The breakdown-resistant lithium-ion solid-state battery separator according to claim 1, characterized in that, The thickness of the composite coating is 2-5 μm.

8. A method for preparing a breakdown-resistant lithium-ion solid-state battery separator, used to prepare the breakdown-resistant lithium-ion solid-state battery separator according to any one of claims 1 to 7, comprising the following specific steps: S1. The polymer matrix and inorganic filler are dispersed in an organic solvent in a certain proportion, and the mixture is ultrasonically / stirred until uniform. The film is then formed on a plate by casting to obtain the base film layer. S2. Dissolve the self-healing polymer in a solvent to prepare a coating or colloid, and apply it evenly to the outer surface of the base film layer using a coating method to obtain the self-healing polymer layer. S3. Mix the polymer matrix with nanoparticles and the second network polymer, disperse the nanoparticles by ultrasonic treatment or ball milling, add an interface enhancer to obtain a mixed slurry, and coat the mixed slurry on the outer surface of the self-healing polymer layer. S4. The coated membrane material is subjected to heat treatment at a temperature of 120-180℃ for 30-60 minutes to obtain the breakdown-resistant lithium-ion solid-state battery separator.

9. A lithium-ion battery, characterized in that, Includes the breakdown-resistant lithium-ion solid-state battery separator as described in any one of claims 1 to 7.

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