PE separator for lead-acid battery and preparation method thereof

Abstract

This invention discloses a PE separator for lead-acid batteries and its preparation method, belonging to the field of lead-acid battery technology. The PE separator, by weight, comprises 120-130 parts silica, 50-55 parts ultra-high molecular weight polyethylene resin powder, 180-200 parts raw material oil, 1-1.5 parts antioxidant, and 2.5-3 parts silicon-polyethylene fiber composite material, wherein the silicon-polyethylene fiber composite material is high molecular weight polyethylene fiber loaded with silica. The silicon-polyethylene fiber composite material added to this PE separator delays the thermo-oxidative aging process through physical barriers, free radical adsorption, increased heat distortion temperature, and synergistic effects with conventional antioxidants. The introduction of the silicon-polyethylene fiber composite material provides anchoring sites for the antioxidant, which can be adsorbed onto the silicon surface through hydrogen bonds or van der Waals forces, reducing its migration and loss rate and extending the effective protection period.

Description

Technical Field

[0001] This invention belongs to the field of lead-acid battery technology, specifically relating to a PE separator for lead-acid batteries and its preparation method. Background Technology

[0002] The separator in a lead-acid battery is one of the core components, primarily responsible for isolating the positive and negative plates to prevent short circuits, absorbing electrolyte, and supporting the active materials of the plates. Currently, in industrial applications, lead-acid battery separators mainly include sintered polyvinyl chloride (PVC) separators, polyethylene (PE) separators, glass fiber composite separators, and AGM separators. Among these, PE separators, using ultra-high molecular weight polyethylene (UHMWPE) and silica as the main raw materials, possess advantages such as low resistance, high porosity, encapsulationability, and excellent chemical stability, thus enjoying widespread use.

[0003] PE separators still face the technical challenge of oxidative aging in practical applications. Lead-acid batteries operate in a harsh environment, with separators constantly immersed in corrosive sulfuric acid electrolyte, and simultaneously subjected to oxidative corrosion from multiple factors including positive electrode active materials, oxygen, peroxides, and chemical impurities. Especially during battery charge-discharge cycles, the temperature of the positive electrode plate continuously rises, and the release of oxygen during water electrolysis at the end of charging creates a high-temperature and high-oxidation-prone operating condition, leading to thermo-oxidative aging of the PE separator.

[0004] Under the combined action of heat and oxygen, the UHMWPE molecular chain undergoes a series of free radical reactions, including initiation, growth, and termination, generating hydrogen peroxide and further decomposing, ultimately causing the polymer macromolecular chain to break. This degradation of the molecular chain leads to the separator material becoming brittle and pulverized, forming voids, losing its insulating function, and consequently causing internal short-circuit failure of the battery.

[0005] To improve the antioxidant properties of PE separators, current technologies primarily rely on adding antioxidants to interrupt the auto-oxidation chain propagation reaction, which has become the mainstream approach. Antioxidants can react with free radicals and peroxide free radicals, inhibiting the formation and decomposition of hydroperoxides, thereby delaying the degradation of polymer chains. In industrial applications, composite antioxidants or a main-auxiliary antioxidant synergistic system are often used, with the antioxidant dosage typically controlled at around 2% of the total PE powder content. Furthermore, increasing the processing oil content has also been proven to improve the antioxidant properties of separators; oil content is positively correlated with the oxidation induction period, and higher oil content helps extend the stability time of the separator in high-temperature oxidizing environments.

[0006] Although the aforementioned techniques improve the oxidation resistance of PE separators, significant technical drawbacks remain in practical applications. First, existing antioxidant systems lack stability under long-term high-temperature oxidation conditions. As battery cycle counts increase, antioxidants gradually deplete or become ineffective, making oxidative aging of the separator inevitable. Second, while simply increasing oil content can extend the oxidation induction period, excessively high oil content can lead to oil leaching, forming black floating matter on the electrolyte surface and contaminating the battery's internal environment.

[0007] In summary, existing PE separator technology still faces challenges in terms of oxidation resistance. Developing a PE separator for lead-acid batteries that also possesses excellent oxidation resistance is of significant technical and practical value for improving the cycle life and reliability of lead-acid batteries. Summary of the Invention

[0008] The purpose of this invention is to provide a PE separator for lead-acid batteries and a method for preparing it, so as to solve the problem of poor oxidation resistance of PE separators for lead-acid batteries.

[0009] The objective of this invention can be achieved through the following technical solutions: The first aspect of the present invention provides a PE separator for lead-acid batteries, comprising, by weight, 120-130 parts of silicon dioxide, 50-55 parts of ultra-high molecular weight polyethylene resin powder, 180-200 parts of raw material oil, 1-1.5 parts of antioxidant, and 2.5-3 parts of silicon-polyethylene fiber composite material, wherein the silicon-polyethylene fiber composite material is silicon dioxide supported on high molecular weight polyethylene fibers.

[0010] In some possible implementations, the diameter of the ultra-high molecular weight polyethylene resin powder is 120-150 μm; the average particle size of silica is 10-25 μm.

[0011] In some possible implementations, the antioxidants are antioxidant 1010 and antioxidant 168, with a mass ratio of antioxidant 1010 to antioxidant 168 of 1:1-2.

[0012] In some possible implementations, the feedstock oil is either a paraffinic mineral oil or a naphthenic mineral oil.

[0013] In some possible implementations, the silicon-polyethylene fiber composite material is prepared by the following steps: At a temperature of 20-30℃, the nonionic surfactant alkylphenol polyoxyethylene ether is dissolved in water with stirring. The ratio of alkylphenol polyoxyethylene ether to water is 1-2 g: 50-100 mL. Then, concentrated ammonia or dilute NaOH solution is added to adjust the pH of the system to 9-11. A silicon source is slowly added dropwise under vigorous stirring, with the molar ratio of silicon source to nonionic surfactant controlled at 1-4: 0.1-0.5. Stirring continues for 30-60 min to form a sol. The silicon source is tetraethyl orthosilicate (TEOS) or sodium silicate solution. Activated ultra-high molecular weight polyethylene (UHMWPE) fibers were added to the sol to ensure complete fiber wetting. Hydrothermal crystallization was performed at 80-120℃ for 12-48 hours. After crystallization, the fibers were allowed to cool naturally to room temperature. The composite fibers were then removed, rinsed with water to prevent clumping, and allowed to stand at room temperature for 5-6 hours. Finally, they were dried in a vacuum drying oven at 50-70℃ for 8-16 hours to obtain the silicon-polyethylene fiber composite material. Silica was then grown in situ on the surface of the activated UHMWPE fibers using a sol-gel method. A nonionic surfactant was used as a template agent (structure directing agent), embedding the surfactant within the pores of the mesoporous silica, thus achieving slow release through the mesoporous channels.

[0014] The materials used in PE separators are mainly silica and polyethylene, which have poor hydrophilicity. During production, wetting agents are usually added to improve the wettability of the PE separator. However, because the wetting agents in the separator have a certain degree of water absorption, a dynamic equilibrium will be reached between the moisture in the air and the water absorbed by the separator when the separator is stored in environments with varying humidity. When the relative humidity in the air is high, the separator will absorb moisture from the air, resulting in a decrease in its insulation resistance. Lead-acid battery separator materials need to have high insulation resistance to reduce leakage current during short-circuit tests of the electrode assembly, ensuring battery performance and safety.

[0015] In this invention, when the separator is stored in a dry state, the wetting agent is fixed within the pores and remains stable without migration. When the battery is injected with electrolyte (dilute sulfuric acid aqueous solution), water molecules preferentially enter the hydrophilic mesoporous pores, replacing the wetting agent molecules and causing them to accumulate precisely. This reduces the contact angle between the separator and the electrolyte, maintains good interfacial wettability, and keeps the separator resistance stable.

[0016] In some possible implementations, the nonionic surfactant is at least one of alkylphenol polyoxyethylene ethers and fatty alcohol polyoxyethylene ethers.

[0017] Nonionic surfactants can be used as template agents. Adding a removal step during the preparation of silicon-polyethylene fiber composites can form mesoporous structures. This invention reduces the removal step, essentially pre-loading the wetting agent into the mesoporous silica channels. In traditional separators, during long-term storage, free wetting agents slowly migrate to the surface, where they undergo auto-oxidation upon contact with oxygen in the air, leading to wetting agent failure. Simultaneously, oxidation products may contaminate the separator surface, weakening its antioxidant capacity. The physical shielding effect of the mesoporous silica in this invention significantly reduces the heat exposure of the wetting agent during extrusion, protecting it from decomposition. This not only improves the effective utilization rate of the wetting agent but also eliminates additional aging sources introduced by wetting agent degradation.

[0018] Mesoporous structures possess a certain adsorption and capture capacity for free radicals and peroxides in electrolytes, which can help delay the diffusion and propagation of oxidation chain reactions. The pore size distribution and surface hydroxyl content of mesoporous silica need to be coordinated and optimized with the oil-based pore-forming agent and antioxidant system to avoid pore blockage or unnecessary interfacial side reactions.

[0019] In some possible implementations, activated ultra-high molecular weight polyethylene fibers are prepared through the following steps: Ultra-high molecular weight polyethylene (UHMWPE) fibers are added to an oxidative acid treatment solution at a temperature of 60-80℃ for 3-4 minutes. After removal, the fibers are washed and dried to obtain activated UHMWPE fibers. The oxidative acid treatment solution is a mixture of potassium chromate, sulfuric acid solution, and water in a ratio of 4g:7g:90-100mL, with the sulfuric acid solution having a mass fraction of 30%.

[0020] In some possible implementations, the treatment temperature is 70℃ and the treatment time is 3 minutes; the oxidizing acid treatment solution is a mixture of potassium chromate, sulfuric acid solution, and water in a ratio of 4g:7g:90mL. The ultra-high molecular weight polyethylene (UHMWPE) fibers have a length of 10-20mm and a diameter of 10μm-50μm. The molecular weight of the UHMWPE fibers is approximately 1.7 million. The molecular weight of the UHMWPE resin powder is approximately 6.8 million.

[0021] The first aspect of this invention provides a method for preparing a PE separator for lead-acid batteries, comprising the following steps: Ultra-high molecular weight polyethylene resin powder, silica, antioxidants, and silicon-polyethylene fiber composite materials are mixed, and then raw material oil is added and mixed further. The mixture is then fed into a twin-screw extruder for extrusion molding. The screw speed is controlled at 15-18 r / min, and the temperatures of each section of the extruder are set as follows: zone 1 180℃, zone 2 190℃, zone 3 200℃, zone 4 205℃, and die head 210℃. After the extrudate is cooled and shaped, it is extracted with a low-boiling-point solvent, ethanol, to extract paraffin from the membrane and form a microporous structure. Finally, it is dried in a vacuum drying oven at 50-60℃ to remove residual solvent, yielding a PE separator for lead-acid batteries.

[0022] The beneficial effects of this invention are: This invention provides a PE separator for lead-acid batteries. The silicon-polyethylene fiber composite material added to this PE separator slows down the thermo-oxidative aging process through physical barriers, free radical adsorption, increased heat distortion temperature, and synergistic effects with conventional antioxidants. The introduction of the silicon-polyethylene fiber composite material provides anchoring sites for antioxidants, which can be adsorbed onto the silicon surface through hydrogen bonds or van der Waals forces, reducing their migration and loss rate and extending the effective protection period.

[0023] The high-density polyethylene fibers used in the silicon-polyethylene fiber composite material possess high strength, high modulus, and excellent chemical corrosion resistance, and have good compatibility with the ultra-high molecular weight polyethylene matrix. Loading with silica simultaneously improves the dispersibility and interfacial compatibility of the inorganic filler, reducing localized weak areas caused by phase separation. The high-density polyethylene fibers themselves possess high strength, high modulus, and excellent chemical corrosion resistance. Based on the good compatibility with the ultra-high molecular weight polyethylene matrix, the fiber morphology forms a three-dimensional network reinforcement skeleton within the separator matrix. When the separator is punctured by the active material of the electrode plate or subjected to mechanical compression of the grid, the fibers can inhibit damage propagation through mechanisms such as bridging, crack deflection, and energy dissipation, thereby improving the structural integrity of the separator during cycling. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Obviously, the following description is merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0026] However, there may be instances where unnecessary detailed descriptions are omitted. For example, detailed descriptions of well-known matters or repetitive descriptions of essentially the same structure may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the following description is provided to enable those skilled in the art to fully understand this application and is not intended to limit the subject matter of the claims.

[0027] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions, and all technical features and optional technical features of this application can be combined to form new technical solutions.

[0028] The following is a detailed description of a PE separator for lead-acid batteries and its preparation method according to an embodiment of this application.

[0029] The following is a detailed description with reference to specific examples.

[0030] Example 1 This embodiment provides a PE separator for lead-acid batteries, comprising, by weight, 125 parts silica, 50 parts ultra-high molecular weight polyethylene resin powder, 190 parts raw material oil, 1 part antioxidant, and 3 parts silicon-polyethylene fiber composite material, wherein the silicon-polyethylene fiber composite material is high molecular weight polyethylene fiber loaded with silica. The antioxidant is antioxidant 1010 and antioxidant 168, with a mass ratio of antioxidant 1010 to antioxidant 168 of 1:1. The raw material oil is paraffinic mineral oil.

[0031] The silicon-polyethylene fiber composite material is prepared through the following steps: Ultra-high molecular weight polyethylene (UHMWPE) fibers were added to an oxidative acid treatment solution at a temperature of 70°C for 3 minutes. After removal, the fibers were washed and dried to obtain activated UHMWPE fibers. The oxidative acid treatment solution was a mixture of potassium chromate, sulfuric acid solution, and water in a ratio of 4g:7g:90mL, with the sulfuric acid solution having a mass fraction of 30%. At 20°C, the nonionic surfactant alkylphenol polyoxyethylene ether (nonylphenol polyoxyethylene ether Tx-15) was dissolved in water and stirred until dissolved. The ratio of alkylphenol polyoxyethylene ether to water was 1 g: 50 mL. Then, concentrated ammonia was added to adjust the pH of the system to 9. A silicon source (tetraethyl orthosilicate TEOS) was slowly added dropwise under vigorous stirring, with the molar ratio of silicon source to alkylphenol polyoxyethylene ether controlled at 1:0.1. Stirring was continued for 30 min to form a sol. Activated ultra-high molecular weight polyethylene fibers were added to the above sol to ensure that the fibers were completely wetted by the sol. The fibers were then hydrothermally crystallized at 100°C for 24 hours. After crystallization, the fibers were naturally cooled to room temperature. The composite fibers were then removed and allowed to stand at room temperature for 5 hours. Finally, the fibers were dried in a vacuum drying oven at 60°C for 16 hours to obtain the silicon-polyethylene fiber composite material.

[0032] The method for preparing the PE separator for lead-acid batteries includes the following steps: Ultra-high molecular weight polyethylene resin powder, silica, antioxidants, and silicon-polyethylene fiber composite materials were mixed, and then raw material oil was added for further mixing. The mixture was then fed into a twin-screw extruder for extrusion molding, with the screw speed controlled at 15 r / min. The temperatures of each section of the extruder were set as follows: zone 1 180℃, zone 2 190℃, zone 3 200℃, zone 4 205℃, and die head 210℃. After the extrudate was cooled and shaped, it was extracted with a low-boiling-point solvent, ethanol, to extract paraffin from the membrane and form a microporous structure. Finally, it was dried in a vacuum drying oven at 60℃ to remove residual solvent, yielding a PE separator for lead-acid batteries.

[0033] Example 2 This embodiment provides a PE separator for lead-acid batteries, which, by weight, includes 120 parts of silica, 50 parts of ultra-high molecular weight polyethylene resin powder, 180 parts of raw material oil, 1 part of antioxidant, and 2.5 parts of silicon-polyethylene fiber composite material. The remaining raw materials and preparation process are the same as in Example 1.

[0034] Example 3 This embodiment provides a PE separator for lead-acid batteries, which, by weight, includes 130 parts of silica, 55 parts of ultra-high molecular weight polyethylene resin powder, 200 parts of raw material oil, 1.5 parts of antioxidant, and 3 parts of silicon-polyethylene fiber composite material. The remaining raw materials and preparation process are the same as in Example 1.

[0035] Example 4 This embodiment provides a PE separator for lead-acid batteries. The difference between this embodiment and embodiment 1 is that the antioxidants are antioxidant 1010 and antioxidant 168, and the mass ratio of antioxidant 1010 to antioxidant 168 is 1:1.5. The other raw materials and preparation process are the same as in embodiment 1.

[0036] Example 5 This embodiment provides a PE separator for lead-acid batteries. Compared with Example 1, the antioxidants in this embodiment are antioxidant 1010 and antioxidant 168, with a mass ratio of antioxidant 1010 to antioxidant 168 of 1:2. The remaining raw materials and preparation process are the same as in Example 1.

[0037] Example 6 This embodiment provides a PE separator for lead-acid batteries. Compared with Example 1, the activated ultra-high molecular weight polyethylene fibers in the silicon-polyethylene fiber composite material are prepared through the following steps: Ultra-high molecular weight polyethylene (UHMWPE) fibers were added to an oxidative acid treatment solution at a temperature of 70°C for 3 minutes. After removal, the fibers were washed and dried to obtain activated UHMWPE fibers. The oxidative acid treatment solution was a mixture of potassium chromate, sulfuric acid solution, and water in a ratio of 4g:7g:100mL, with the sulfuric acid solution having a mass fraction of 30%. The remaining raw materials and preparation process were the same as in Example 1.

[0038] Example 7 This embodiment provides a PE separator for lead-acid batteries. Compared with Example 1, the silicon-polyethylene fiber composite material in this embodiment is prepared by the following steps: At 20°C, the nonionic surfactant alkylphenol polyoxyethylene ether (nonylphenol polyoxyethylene ether Tx-15) was dissolved in water and stirred until dissolved. The ratio of alkylphenol polyoxyethylene ether to water was 1 g: 50 mL. Subsequently, concentrated ammonia was added to adjust the pH of the system to 9. A silicon source (tetraethyl orthosilicate) was slowly added dropwise under vigorous stirring, with the molar ratio of silicon source to alkylphenol polyoxyethylene ether controlled at 1:0.2. Stirring was continued for 30 min to form a sol. Activated ultra-high molecular weight polyethylene fiber (same as in Example 1) was added to the above sol to ensure that the fiber was completely wetted by the sol. Hydrothermal crystallization was carried out at 100°C for 24 hours. After crystallization, the fiber was naturally cooled to room temperature. The composite fiber was taken out, rinsed with water to prevent it from sticking together, and left to stand at room temperature for 5 hours. It was then dried in a vacuum drying oven at 60°C for 16 hours to obtain the silicon-polyethylene fiber composite material. The remaining raw materials and preparation process were the same as in Example 1.

[0039] Example 8 This embodiment provides a PE separator for lead-acid batteries. Compared with Example 1, the silicon-polyethylene fiber composite material in this embodiment is prepared by the following steps: At 20°C, the nonionic surfactant alkylphenol polyoxyethylene ether (octylphenol polyoxyethylene ether TX-100) was dissolved in water and stirred until dissolved. The ratio of alkylphenol polyoxyethylene ether to water was 1 g: 50 mL. Then, concentrated ammonia was added to adjust the pH of the system to 9. A silicon source (tetraethyl orthosilicate TEOS) was slowly added dropwise under vigorous stirring, with the molar ratio of silicon source to alkylphenol polyoxyethylene ether controlled at 1:0.1. Stirring was continued for 30 min to form a sol. Activated ultra-high molecular weight polyethylene fiber (same as in Example 1) was added to the above sol to ensure that the fiber was completely wetted by the sol. Hydrothermal crystallization was carried out at 100°C for 24 hours. After crystallization, the fiber was naturally cooled to room temperature. The composite fiber was taken out, rinsed with water to prevent it from sticking together, and left to stand at room temperature for 5 hours. It was then dried in a vacuum drying oven at 60°C for 16 hours to obtain the silicon-polyethylene fiber composite material. The remaining raw materials and preparation process were the same as in Example 1.

[0040] Comparative Example 1 The difference between this comparative example and Example 1 is that no antioxidant is added, while the other raw materials and preparation process remain the same as in Example 1.

[0041] Comparative Example 2 The difference between this comparative example and Example 1 is that no silicon-polyethylene fiber composite material is added, while the other raw materials and preparation methods remain the same as in Example 1.

[0042] Comparative Example 3 The difference between this comparative example and Example 1 lies in the preparation process of the "silicon-polyethylene fiber composite material." Specifically: after crystallization, the composite fibers were allowed to cool naturally to room temperature, then removed and rinsed with water to prevent clumping. They were then washed with a mixture of ethanol and concentrated hydrochloric acid (volume ratio 2:1), and then alternately washed four times with deionized water and anhydrous ethanol. The remaining raw materials and preparation process remained the same as in Example 1. The purpose was to remove the template agent.

[0043] Test Example 1 Performance tests were performed on Examples 1-8 and Comparative Examples 1-3; Antioxidant activity: The mass concentration was (1.300±0.005) g / cm³. 3 A mixed oxidizing solution was prepared by mixing sulfuric acid solution and hydrogen peroxide solution with a mass fraction of 30% at a volume ratio of 3.8:1. The sample was completely immersed in the mixed oxidizing solution at a treatment temperature of 80±2℃ for 20 hours. After removal, the sample was rinsed with warm water until neutral (pH test paper test), and then the surface moisture was absorbed with filter paper. The transverse elongation of the sample was tested using a microcomputer-controlled electronic universal testing machine. The results are shown in Table 1: Table 1

[0044] As can be seen from Table 1, based on the comparison between Example 1 and Comparative Example 1, the PE separator without added antioxidant has a low transverse elongation after oxidation. In Comparative Example 2, the lack of support from the silicon-polyethylene fiber composite material leads to a decrease in mechanical properties. In Comparative Example 3, the removal of the template agent may affect the dispersibility of the silicon-polyethylene fiber composite material in the system, resulting in a decrease in performance.

[0045] Test Example 2 Electrode assembly short circuit test leakage current test: After cutting the partition into 25mm×15mm pieces, use an insulation resistance tester to test the insulation resistance under a relative humidity of 85%.

[0046] The resistivity was measured after immersion in sulfuric acid electrolyte for 30 min, 3 h, and 6 h, and the results are shown in Table 2 below: Table 2

[0047] According to Table 2, a comparison with Example 1 and Comparative Examples 1-3 shows that the introduction of a silicon-polyethylene fiber composite material in this invention stabilizes the separator resistance. In the silicon-polyethylene fiber composite material of this invention, the wetting agent is fixed within the pores, remaining stable and non-migrating. When the battery is injected with electrolyte (dilute sulfuric acid aqueous solution), water molecules preferentially enter the hydrophilic mesoporous channels, replacing the wetting agent molecules and precisely enriching them, thus reducing the contact angle between the separator and the electrolyte and maintaining good interfacial wettability.

[0048] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A PE separator for lead-acid batteries, characterized by, By weight, it includes 120-130 parts of silica, 50-55 parts of ultra-high molecular weight polyethylene resin powder, 180-200 parts of raw material oil, 1-1.5 parts of antioxidant, and 2.5-3 parts of silicon-polyethylene fiber composite material, wherein the silicon-polyethylene fiber composite material is high molecular weight polyethylene fiber loaded with silica.

2. The PE separator for lead-acid batteries according to claim 1, characterized by The diameter of the ultra-high molecular weight polyethylene resin powder is 120-150 μm; the average particle size of silica is 10-25 μm.

3. The PE separator for lead-acid batteries according to claim 1, characterized in that, The antioxidants are antioxidant 1010 and antioxidant 168, with a mass ratio of antioxidant 1010 to antioxidant 168 of 1:1-2.

4. The PE separator for lead-acid batteries according to claim 1, characterized in that, The feedstock oil is either paraffinic mineral oil or naphthenic mineral oil.

5. A PE separator for lead-acid batteries according to claim 1, characterized in that, Silicon-polyethylene fiber composite materials are prepared through the following steps: At a temperature of 20-30℃, dissolve the nonionic surfactant in water and stir until dissolved. Then, add a silicon source to adjust the pH of the system to 9-11. The molar ratio of silicon source to nonionic surfactant is controlled at 1-4:0.1-0.

5. Continue stirring for 30-60 minutes to form a sol. Activated ultra-high molecular weight polyethylene fibers were added to the above sol and hydrothermally crystallized at 80-120℃ for 12-48 hours. After crystallization, the mixture was naturally cooled to room temperature, removed, and left to stand at room temperature for 5-6 hours. It was then vacuum dried at 50-70℃ for 8-16 hours to obtain the silicon-polyethylene fiber composite material.

6. A PE separator for lead-acid batteries according to claim 5, characterized in that, The nonionic surfactant is at least one of alkylphenol polyoxyethylene ethers and fatty alcohol polyoxyethylene ethers.

7. A PE separator for lead-acid batteries according to claim 5, characterized in that, The activated ultra-high molecular weight polyethylene fiber is prepared through the following steps: Ultra-high molecular weight polyethylene (UHMWPE) fibers are added to an oxidative acid treatment solution at a temperature of 60-80℃ for 3-4 minutes. After removal, the fibers are washed and dried to obtain activated UHMWPE fibers. The oxidative acid treatment solution is a mixture of potassium chromate, sulfuric acid solution, and water in a ratio of 4g:7g:90-100mL, with the sulfuric acid solution having a mass fraction of 30%.

8. A PE separator for lead-acid batteries according to claim 1, characterized in that, The treatment temperature is 70℃ and the treatment time is 3 minutes; the oxidizing acid treatment solution is a mixture of potassium chromate, sulfuric acid solution and water in a ratio of 4g:7g:90mL.

9. A method for preparing a PE separator for lead-acid batteries, used to prepare the PE separator for lead-acid batteries according to any one of claims 1-8, characterized in that, Includes the following steps: Ultra-high molecular weight polyethylene resin powder, silica, antioxidant and silicon-polyethylene fiber composite material are mixed, then raw material oil is added and mixed again. The mixture is fed into a twin-screw extruder for extrusion molding. After the extrudate is cooled and shaped, oil is extracted, gas is removed and dried to obtain PE separator for lead-acid batteries.

10. A method for preparing a PE separator for a lead-acid battery according to claim 9, characterized in that, Extrusion molding: The screw speed is controlled at 15-18 r / min, and the temperature of each section of the extruder is set as follows: Zone 1 180-185℃, Zone 2 190-195℃, Zone 3 190-200℃, Zone 4 200-205℃, and Die head 200-210℃.

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