High breakdown strength battery separator, method of making and battery

Abstract

The application discloses a high-breakdown-strength battery diaphragm, a preparation method thereof and a battery. The high-breakdown-strength battery diaphragm comprises a porous microstructure, which contains a plurality of insulating core fibers and a voltage-resistant sheath layer coated on the insulating core fibers, and two or more insulating core fibers are interwoven to jointly define one or more micro-holes; the insulating breakdown strength of the high-breakdown-strength battery diaphragm is not less than 110 V / μm, and the core-sheath structure formed by coating the insulating core fibers with the voltage-resistant material maintains the overall thickness change rate of the diaphragm at a low level, so that the high insulating breakdown performance is realized at a low thickness increment.

Description

Technical Field

[0001] This invention relates to the field of battery manufacturing technology, and particularly to the manufacture of separators, especially to a high breakdown strength separator, its preparation method, and its application. Background Technology

[0002] Lithium-ion rechargeable batteries have advantages such as high operating voltage, high energy density, long cycle life, rapid charging and discharging, and low pollution, and are widely used in everyday electronic products, electrical appliances, digital products, as well as power batteries and energy storage batteries. In recent years, with the rapid development of new energy vehicles and the energy storage industry, the market is increasingly demanding higher energy density and higher power output from lithium-ion rechargeable batteries, while also raising higher requirements for safety performance.

[0003] The breakdown strength of the separator determines its ability to resist electrical breakdown under an applied electric field. A low breakdown strength indicates a weak barrier to electrons, making the separator susceptible to electrical breakdown under higher voltage conditions due to localized electric field concentration and insufficient insulation. This can lead to conduction between the positive and negative electrodes, causing internal short circuits and safety issues. Current technology places relatively little emphasis on the breakdown strength of separators. While separator products may meet ion transport and mechanical performance requirements, their low breakdown strength makes it difficult to meet the high safety demands of high energy density and high power output.

[0004] Therefore, how to provide a lithium-ion secondary battery separator with high breakdown strength, good ion transport performance, and safe use is one of the technical problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0005] The present invention is dedicated to solving the above-mentioned problems, and it should be understood that technical problems not mentioned above are also obvious from the following description of the present invention.

[0006] One objective of this invention is to provide a high breakdown strength battery separator, which includes a porous microstructure containing a plurality of insulating core fibers and a voltage-resistant sheath layer covering the insulating core fibers, wherein two or more of the insulating core fibers are interwoven to jointly define one or more micropores, wherein the high breakdown strength battery separator has an insulation breakdown strength of not less than 110 V / μm.

[0007] In some embodiments, the insulating core fiber comprises polyolefin.

[0008] In some embodiments, the voltage-resistant sheath comprises a voltage-resistant material, wherein the voltage-resistant material comprises hindered phenolic compounds, aramid fibers, polyimides, polyetherimides, or any combination thereof coated thereon.

[0009] In some embodiments, the voltage-resistant material comprises hindered phenolic compounds, wherein the hindered phenolic compounds include monophenolic hindered phenols, bisphenolic hindered phenols, polyfunctional hindered phenols, or any combination thereof.

[0010] In some embodiments, the voltage-resistant material includes aramid fiber.

[0011] In some embodiments, the voltage-resistant material includes polyimide, polyetherimide, or any combination thereof.

[0012] In some embodiments, the high breakdown strength battery separator further satisfies at least one of the following: the glass transition temperature of the voltage-resistant sheath is greater than 150°C.

[0013] Another objective of this invention is to provide a method for manufacturing a high breakdown strength battery separator, comprising the following steps: Step S1: preparing a base film precursor, wherein the base film precursor comprises: a porous microstructure formed by a plurality of insulating core fibers, wherein two or more of the insulating core fibers together form one or more micropores; and a pore-forming material in the micropores; Step S2: immersing the base film precursor in an extraction solution, wherein the extraction solution comprises an extraction solvent and a voltage-resistant material dissolved therein, thereby dissolving the pore-forming material in the extraction solvent, exposing the one or more micropores to obtain a base film; and Step S3: permeating the voltage-resistant material through the micropores to coat the insulating core fibers to form a voltage-resistant sheath layer, thereby obtaining a high breakdown strength battery separator, wherein the high breakdown strength battery separator has an insulation breakdown strength of not less than 110 V / μm.

[0014] In some embodiments, step S2 further includes: step S20: adding the voltage-resistant material to the extraction solvent to obtain the extraction solution, wherein step S20 may be performed before or after soaking the base film precursor, or simultaneously with soaking the base film precursor.

[0015] In some embodiments, the insulating core fiber comprises polyolefin.

[0016] In some embodiments, the voltage-resistant material includes hindered phenolic compounds, aramid fibers, polyimides, polyetherimides, or any combination thereof.

[0017] In some embodiments, the voltage-resistant material comprises a hindered phenolic compound, wherein the hindered phenolic compound includes monophenolic hindered phenols, bisphenolic hindered phenols, polyfunctional hindered phenols, or any combination thereof.

[0018] In some embodiments, the voltage-resistant material includes aramid fiber.

[0019] In some embodiments, the voltage-resistant material includes polyimide, polyetherimide, or any combination thereof.

[0020] In some embodiments, the high breakdown strength battery separator further satisfies at least one of the following: the glass transition temperature of the voltage-resistant material is greater than 150°C.

[0021] In some embodiments, the thickness of the base film is T0, and the thickness of the high breakdown strength battery separator is T1, wherein T1:T0 is (1.0~1.1):1.

[0022] In some implementations, the insulation breakdown strength gain of the high breakdown strength battery separator is greater than 10%, based on the insulation breakdown strength of the base film.

[0023] Another object of the present invention is to provide a battery comprising a high breakdown strength battery separator as described above or a high breakdown strength battery separator prepared by the method described above.

[0024] The advantages of this invention compared to prior art are that, on the porous microstructure of the base membrane, a voltage-resistant sheath layer is uniformly coated on the insulating core fiber to form a core-sheath structure, thereby improving the insulation breakdown strength of the separator. The insulation breakdown strength of the high-breakdown-strength battery separator reaches at least 110 V / μm. In addition, the voltage-resistant sheath layer is coated with a voltage-resistant material, such as an aromatic voltage-resistant material. Each molecule of the aromatic voltage-resistant material attached to the surface of the insulating core fiber has multiple aromatic rings, which effectively improves the voltage breakdown resistance of the voltage-resistant sheath layer. The high density of aromatic rings in the voltage-resistant sheath layer allows it to gain anti-breakdown performance with a relatively thin thickness, while mitigating the problem of membrane thickening after adding the coating. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the porous microstructure of the high breakdown strength battery separator of the present invention; and Figure 2 This is a flowchart illustrating the preparation method of the high breakdown strength battery separator of the present invention. Detailed Implementation

[0026] The following examples, illustrated with figures, illustrate specific embodiments of the present invention.

[0027] The present invention will be described in detail below with reference to specific embodiments. It should be noted that the embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

[0028] Please see Figure 1The first embodiment of the present invention provides a high breakdown strength battery separator, which includes a porous microstructure (1) containing a plurality of insulating core fibers (11) and a voltage-resistant sheath layer (12) covering the insulating core fibers (11), wherein two or more of the insulating core fibers (11) are interwoven to jointly define one or more micropores (P).

[0029] In a common implementation, the high-breakdown-strength battery separator has an insulation breakdown strength of not less than 110 V / μm; preferably, not less than 115 V / μm; more preferably, not less than 120 V / μm. Specifically, the so-called "insulation breakdown strength" is obtained by measuring the insulation breakdown voltage of the entire separator and dividing this insulation breakdown voltage value by the separator thickness value, which characterizes the magnitude of the breakdown voltage that each unit thickness of the separator can withstand.

[0030] In some embodiments, the insulating core fiber (11) comprises a polyolefin, such as polyethylene, polypropylene, polybutene, polypentene, polyhexene, polyoctene, or a copolymer or mixture thereof of at least one of ethylene, propylene, butene, pentene, 4-methylpentene, hexene, and octene; preferably, the polyolefin is polyethylene.

[0031] In some embodiments, the voltage-resistant sheath (12) comprises a voltage-resistant material, which may be an aromatic voltage-resistant material, referring to an organic monomer molecule containing one or more aromatic rings, or a polymer composed of one or more of the aforementioned organic monomer molecules, such as aramid, polyimide, polyetherimide, hindered phenolic compounds, or any combination thereof coated together.

[0032] In a preferred embodiment, the voltage-resistant material is polyetherimide, specifically a polyetherimide with a similar structure and / or properties to the ULTEM type. The polyetherimide may be, for example, a polyetherimide formed from 4,4'-[isopropylidene diphenoxy] phthalic anhydride and m-phenylenediamine (BPADA-MPD type polyetherimide), a polyetherimide sulfone formed from 4,4'-[isopropylidene diphenoxy] phthalic anhydride and 4,4'-diaminodiphenyl sulfone (BPADA-DDS type polyetherimide sulfone), a copolyetherimide formed from 4,4'-[isopropylidene diphenoxy] phthalic anhydride, pyromellitic dianhydride and m-phenylenediamine (BPADA-PMDA-MPD copolyetherimide), or a modified polyetherimide formed from BPADA and other aromatic diamines. Common commercial products include Ultem 1010 type polyetherimide, Ultem 1000 type polyetherimide, or Ultem 1010F type polyetherimide.

[0033] In a preferred embodiment, the voltage-resistant material is a hindered phenolic compound, wherein the hindered phenolic compound includes monophenolic hindered phenols, bisphenolic hindered phenols, polyfunctional hindered phenols, or any combination thereof.

[0034] Specifically, the hindered phenolic monophenol type can be, for example, 2,6-di-tert-butyl-4-methylphenol, also known as butylated hydroxytoluene (BHT); or, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, but is not limited thereto.

[0035] Specifically, bisphenol-type hindered phenols can be, for example: 2,2'-Methylenebis(4-methyl-6-tert-butylphenol); 2,2'-Methylenebis(4-ethyl-6-tert-butylphenol); 4,4'-Butylidenebis(3-methyl-6-tert-butylphenol); Thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; 1,6-Hexamethylenebis(3,5-di-tert-butyl-4-hydroxycinnamate). bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate); triethylene glycol bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]; or ethylene glycol bis(oxyethylene) bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], but not limited to these.

[0036] Specifically, hindered phenols with multiple functional groups can be, for example: 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane compounds; pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), with common commercial formulations such as Irganox. 1010; Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, commonly available as Irganox 1076; Thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], commonly available as Irganox 1035; Calcium bis(ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate), commonly available as Irganox 1425, but not limited to these.

[0037] In some embodiments, the glass transition temperature of the voltage-resistant sheath is greater than 150°C; preferably, the glass transition temperature of the voltage-resistant sheath is 250~350°C.

[0038] In some embodiments, the present invention is particularly applicable to ultrathin battery separators, wherein the thickness of the high breakdown strength battery separator is no more than 10 micrometers, preferably 9 to 10 micrometers, more preferably 9.0 micrometers, 9.1 micrometers, 9.2 micrometers, 9.3 micrometers, 9.4 micrometers, 9.5 micrometers, 9.6 micrometers, 9.7 micrometers, 9.8 micrometers, 9.9 micrometers or 10 micrometers.

[0039] Please see Figure 2The second embodiment of the present invention provides a method for manufacturing a high breakdown strength battery separator, which includes the following steps: Step S1: Prepare a base film precursor, wherein the base film precursor comprises a porous microstructure and a porous material in the porous microstructure; Step S2: Immerse the base film precursor in an extraction solution, wherein the extraction solution includes an extraction solvent and a voltage-resistant material dissolved therein, thereby dissolving the porous material in the extraction solvent, exposing one or more micropores in the porous microstructure to obtain a base film, wherein the micropores are formed by two or more insulating core fibers; and Step S3: Allow the voltage-resistant material to penetrate the micropores to coat the insulating core fiber and form a voltage-resistant sheath layer, thereby obtaining a high-breakdown-strength battery separator.

[0040] In a common implementation, the extraction solvent contains 0.1 wt% to 1.0 wt% of a voltage-resistant material, preferably 0.1 wt% to 0.5 wt% of a voltage-resistant material.

[0041] In some implementations, the thickness of the base film is no greater than 9 micrometers.

[0042] In a common implementation, the porosity of the porous microstructure is 30% to 60%, preferably 40% to 50%, and more preferably 45% to 50%.

[0043] In some embodiments, the high-breakdown-strength battery separator has an insulation breakdown strength gain rate greater than 10%, preferably greater than 15%, and more preferably greater than 20%, based on the insulation breakdown strength of the base film.

[0044] In a common implementation, the thickness of the base film is T0, and the thickness of the high breakdown strength battery separator is T1, with T1:T0 being (1.0~1.1):1, preferably (1.0~1.07):1, and more preferably (1.0~1.01):1.

[0045] In a common implementation, the voltage-resistant material, with its good compatibility with the extraction solvent, coats the surface of the insulating core fiber (e.g., polyolefin fiber) through microporous permeation to form a sheath structure. The microporous permeation process can be achieved by capillary permeation, negative pressure permeation, or both, without particular limitation. Under the above permeation conditions, the voltage-resistant material can uniformly penetrate and coat the surface of each insulating core fiber along the gaps between the insulating core fibers without overfilling or blocking the micropores formed between the insulating core fibers. Thus, while achieving sheath coating on the fiber surface, it also maintains the pore structure inside the membrane, ensuring its air permeability.

[0046] In a common implementation, the extraction solvent may be a poor solvent for porous microstructured materials (e.g., polyolefins) and a good solvent for voltage-resistant materials. Non-limiting examples of the extraction solvent may include toluene, dichloromethane, 1,1,1-trichloroethane, hydrocarbons such as n-hexane or cyclohexane, halogenated hydrocarbons such as fluorides, alcohols such as ethanol or isopropanol, or ketones such as acetone, 2-butanone, or N-methylpyrrolidone.

[0047] In some implementations, step S2 further includes: Step S20: Add the voltage-resistant material to the extraction solvent, wherein step S20 may be performed before or after soaking the base film precursor, or simultaneously with soaking the base film precursor; preferably, step S20 is performed simultaneously with soaking the base film precursor.

[0048] In the second embodiment, the specific conditions and parameters such as the insulating core fiber, the voltage-resistant material, the glass transition temperature of the voltage-resistant material, and the thickness of the high breakdown strength battery separator have been described in detail in the first embodiment, and will not be repeated here.

[0049] A third embodiment of the present invention provides a battery comprising a high breakdown strength battery separator as provided in the first embodiment or a high breakdown strength battery separator prepared by the method provided in the second embodiment.

[0050] The following examples illustrate the technical effects achieved by the present invention. However, these examples are not intended to limit the implementation of the present invention, and the interpretation of the scope of protection of the present invention shall still be based on the contents of the claims.

[0051] Preparation of high breakdown strength battery separators Example 1:

[0052] Using toluene as a solvent, a coating solution containing 0.1 wt% Irganox 1010 (BASF) was prepared using a voltage-resistant material containing an aromatic ring.

[0053] The prepared coating solution was applied to a wet-processed PE separator (SEMCORP, SV9, 9 μm thick, 48% porosity). After wiping away excess coating solution, the separator was dried to obtain a high-breakdown-strength battery separator with no significant change in thickness and porosity. The insulation breakdown voltage reached 1090 V, and the insulation breakdown strength calculated in units of separator thickness was 121.11 V / μm. Compared with the wet-processed PE separator provided in Comparative Example 1, the overall insulation breakdown strength of the separator increased by 18.48%. Example 2:

[0054] The preparation method of the high breakdown strength battery separator is the same as in Example 1, except that the voltage-resistant material is changed to BHT (Butylated Hydroxytoluene, Zhengzhou Meiya Chemical Products Co., Ltd.). The thickness and porosity of the obtained high breakdown strength battery separator are not significantly changed, the insulation breakdown voltage reaches 1110 V, and the insulation breakdown strength calculated in units of separator thickness is 123.33 V / μm. Compared with the wet-process PE separator provided in Comparative Example 1, the overall insulation breakdown strength gain rate of the separator reaches 20.65%. Example 3:

[0055] A coating solution containing 0.1 wt% polyimide (PI, synthesized by SEMCORP) was prepared using NMP as a solvent.

[0056] The prepared coating solution was applied to a wet-prepared PE membrane (SEMCORP, SV9, 9 μm thick, 48% porosity), and excess coating solution was wiped off.

[0057] Next, the PE diaphragm coated with voltage-resistant material is immersed in water to fix the PI.

[0058] Next, the water was dried to obtain a high-breakdown-strength battery separator with a slightly increased thickness of 9.28 μm and a thickness change rate of about 3.11%, but its porosity did not change significantly. The insulation breakdown voltage reached 1085 V, and the calculated insulation breakdown strength was 116.92 V / μm. Compared with Comparative Example 1, the overall insulation breakdown strength of the separator increased by 14.38%. Example 4

[0059] The preparation method of the high breakdown strength battery separator is the same as in Example 3, except that the voltage-resistant material is polyetherimide (PEI, Ultem1010 from Sabic). The thickness of the obtained high breakdown strength battery separator is slightly increased to 9.47 μm, with a thickness change rate of about 5.22%, but its porosity does not change significantly. The insulation breakdown voltage reaches 1089 V, and the calculated insulation breakdown strength is 114.99 V / μm. Compared with Comparative Example 1, the gain rate of the overall insulation breakdown strength of the separator reaches 12.50%. Example 5

[0060] The preparation method of the high breakdown strength battery separator is the same as in Example 3, except that the voltage-resistant material is para-aramid. The thickness of the obtained high breakdown strength battery separator is slightly increased to 9.35 μm, with a thickness change rate of about 3.89%, but its porosity does not change significantly. The insulation breakdown voltage reaches 1122 V, and the calculated insulation breakdown strength is 120 V / μm. Compared with Comparative Example 1, the gain rate of the overall insulation breakdown strength of the separator reaches 17.40%. Example 6

[0061] In the preparation process of the wet-process PE separator (SEMCORP, SV9, thickness 9μm, porosity 48%), a voltage-resistant material is added during the extraction process. In this embodiment, dichloromethane (MC) is used in the extraction process. 0.5 wt% BHT is added to the last extraction tank of the extraction process. The PE separator coated with BHT is taken out, excess extraction solvent is wiped off, and it is dried to obtain a high breakdown strength battery separator. Its thickness and porosity do not change significantly, the insulation breakdown voltage reaches 1140 V, and the calculated insulation breakdown strength is 126.67 V / μm. Compared with Comparative Example 1, the gain rate of the overall insulation breakdown strength of the separator reaches 23.91%.

[0062] Comparative Example 1: Insulation breakdown voltage and insulation breakdown strength were directly measured using untreated wet-process PE membranes (SEMCORP, SV9, 9μm thickness, 48% porosity).

[0063] Comparative Example 2: The battery separator preparation method of Comparative Example 2 adopts the traditional "post-coating process". After the wet PE separator extraction process, the extraction solution containing the voltage-resistant material is used to coat the PE separator surface. The extraction solvent and voltage-resistant material are the same as in Example 5, except that the concentration of para-aramid is 6.0 wt%. The preparation method is ordinary coating after wet PE separator extraction. The thickness of the obtained battery separator increases to 10.5 μm, with a thickness change rate of about 16.67%, but its porosity does not change significantly. The insulation breakdown voltage is 1150 V, and the calculated insulation breakdown strength is 109.52 V / μm. Compared with Comparative Example 1, the overall insulation breakdown voltage gain of the separator is 7.14%.

[0064] Insulation breakdown voltage test and evaluation of insulation breakdown strength The insulation breakdown voltage test is mainly conducted according to GB / T 1408.1-2016 "Test Methods for Electrical Strength of Insulating Materials - Part 1: Tests at Power Frequency". Before the test, high-breakdown-strength battery separator samples with smooth, clean surfaces, free of wrinkles, pinholes, and obvious defects are placed in a standard environment of 23±2℃ and 50±5% relative humidity for full conditioning to eliminate environmental stress and moisture absorption effects. Then, the samples are placed flat between the parallel plates and rounded electrodes of the breakdown tester. Insulating oil is used as an auxiliary medium to avoid surface arcing. A power frequency AC voltage is applied and increased at a constant rate until insulation breakdown occurs and the current increases sharply. The instrument automatically records the corresponding breakdown voltage value. Each test group tests 5-10 test points and discards abnormal data such as edge breakdown. The thickness at each effective breakdown test point is measured individually. The dielectric strength (breakdown strength) is calculated as: Dielectric strength (breakdown strength) = Breakdown voltage (V) ÷ The breakdown strength of each test point is calculated based on the thickness (μm) of the corresponding test point. Finally, the arithmetic mean of the effective test point breakdown strengths is used as the evaluation result of the insulation withstand voltage performance of the sample.

[0065] The insulation breakdown voltage of the diaphragms in Examples 1 to 9 and Comparative Examples 1 and 2 was measured five times. The average value was taken as the insulation breakdown voltage value. The average insulation breakdown strength was calculated according to the formula: breakdown strength = breakdown voltage (V) ÷ thickness (μm). The measurement results are shown in Table 1 below. On the other hand, the "insulation breakdown voltage gain ratio" is obtained by taking the insulation breakdown strength value of Comparative Example 1 as the reference value (B1), subtracting the insulation breakdown strength value (X) of each example from this reference value (B1), and then dividing by this reference value (B1). That is: insulation breakdown strength gain ratio (%) = [(X-B1) ÷ B1]*100. The calculation results are shown in Table 1 below.

[0066] Table 1 As shown in Table 1, voltage-resistant materials, especially hindered phenolic compounds, can uniformly penetrate into the micropores under the influence of the extraction solvent, reducing the thickness variation after membrane coating and achieving an overall increase in the insulation breakdown strength of the membrane. In contrast, in Comparative Example 2, which uses a post-coating process, the adhesion between the coating and the substrate is significantly lower than that of the extraction-in-situ addition process. The aramid coating does not fully penetrate the porous structure of the substrate, resulting in a significant increase in thickness. At the same time, at the unit thickness level, the overall insulation breakdown strength of the membrane not only does not gain, but also shows a decline in insulation breakdown strength. Therefore, the extraction-in-situ addition process used in this invention not only improves the overall insulation breakdown voltage of the membrane and increases the insulation breakdown strength, but also allows for the effective penetration of voltage-resistant materials through micropore penetration, resulting in a thickness variation of less than 6% after membrane coating, achieving high breakdown strength, and is suitable for manufacturing ultra-thin battery membranes.

[0067] The above content involving common knowledge will not be described in detail, as those skilled in the art will understand.

[0068] The embodiments described above are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A high breakdown strength battery separator, characterized in that, It includes a porous microstructure containing a plurality of insulating core fibers and a voltage-resistant sheath layer covering the insulating core fibers, wherein two or more of the insulating core fibers are interwoven to jointly define one or more micropores, and the high breakdown strength battery separator has an insulation breakdown strength of not less than 110 V / μm.

2. The high breakdown strength battery separator according to claim 1, characterized in that, The insulating core fiber comprises polyolefin.

3. The high breakdown strength battery separator according to claim 1, characterized in that, The voltage-resistant sheath layer comprises a voltage-resistant material, wherein the voltage-resistant material includes hindered phenolic compounds, aramid fibers, polyimides, polyetherimides, or any combination thereof.

4. The high breakdown strength battery separator according to claim 3, characterized in that, The voltage-resistant material includes hindered phenolic compounds, wherein the hindered phenolic compounds include monophenolic hindered phenols, bisphenolic hindered phenols, polyfunctional hindered phenols, or any combination thereof.

5. The high breakdown strength battery separator according to claim 3, characterized in that, The voltage-resistant material includes aramid fiber.

6. The high breakdown strength battery separator according to claim 3, characterized in that, The voltage-resistant material includes polyimide, polyetherimide, or any combination thereof.

7. A method for manufacturing a high breakdown strength battery separator, characterized in that, Includes the following steps: Step S1: Prepare a base film precursor, wherein the base film precursor comprises: A porous microstructure formed by a plurality of insulating core fibers, wherein two or more of the insulating core fibers together form one or more micropores; and A porous material is used to fill the micropores; Step S2: Immerse the base film precursor in an extraction solution, wherein the extraction solution includes an extraction solvent and a voltage-resistant material dissolved therein, thereby dissolving the pore-forming material in the extraction solvent, exposing one or more micropores to obtain a base film; and Step S3: Allow the voltage-resistant material to penetrate the micropores to coat the insulating core fiber and form a voltage-resistant sheath layer, thereby obtaining a high-breakdown-strength battery separator, wherein the insulation breakdown strength of the high-breakdown-strength battery separator is not less than 110 V / μm.

8. The manufacturing method according to claim 7, characterized in that, Step S2 further includes: Step S20: Add the voltage-resistant material to the extraction solvent to obtain the extraction solution, wherein step S20 may be performed selectively before or after soaking the base film precursor, or simultaneously with soaking the base film precursor.

9. The manufacturing method according to claim 7, characterized in that, The insulating core fiber comprises polyolefin.

10. The manufacturing method according to claim 7, characterized in that, The voltage-resistant material comprises hindered phenolic compounds, aramid fibers, polyimides, polyetherimides, or any combination thereof.

11. The manufacturing method according to claim 10, characterized in that, The voltage-resistant material includes hindered phenolic compounds, wherein the hindered phenolic compounds include monophenolic hindered phenols, bisphenolic hindered phenols, polyfunctional hindered phenols, or any combination thereof.

12. The manufacturing method according to claim 10, characterized in that, The voltage-resistant material includes aramid fiber.

13. The manufacturing method according to claim 10, characterized in that, The voltage-resistant material includes polyimide, polyetherimide, or any combination thereof.

14. The manufacturing method according to claim 7, characterized in that, The thickness of the base film is T0, and the thickness of the high breakdown strength battery separator is T1, wherein T1:T0 is (1.0~1.1):

1.

15. The manufacturing method according to claim 7, characterized in that, Based on the insulation breakdown strength of the base film, the insulation breakdown strength gain rate of the high breakdown strength battery separator is greater than 10%.

16. A battery, characterized in that, This includes high breakdown strength battery separators prepared according to any one of claims 1 to 6 or according to any one of claims 7 to 15.

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