Preparation method and application of modified polyphenyl ether (PPO)-based coated polyolefin diaphragm
Through the preparation method of modified polyphenylene ether coated polyolefin separator, the problems of poor wetting and insufficient thermal stability in lithium-ion batteries are solved, and higher thermal stability and electrolyte wetting are achieved, reducing the risk of thermal runaway, and improving the safety and performance of lithium-ion batteries.
Patent Information
- Application Number
- CN202510509099.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-22
- Publication Date
- 2025-07-29
AI Technical Summary
The existing polyolefin separators have problems such as poor electrolyte wetting and insufficient thermal stability in lithium-ion batteries, resulting in a high risk of thermal runaway.
The preparation method of modified polyphenylene ether (PPO) coated polyolefin separator is adopted, bromine atoms are introduced through bromination treatment, and a BPPO coating is constructed, and a porous structure is formed on the PE base film by non-solvent phase conversion method. A cross-linking network is constructed in combination with the in-situ amination reaction of 3-aminopropyl trihydroxysilane, and highly polar amine groups and hydroxy functional groups are introduced.
It significantly improves the thermal stability of the separator and the wetting properties of the electrolyte, reduces the thermal shrinkage rate and the contact angle of the electrolyte, and improves the safety and performance of lithium-ion batteries.
Smart Images
Figure CN120389197A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a preparation method and application of a modified polyphenylene ether (PPO)-coated polyolefin diaphragm, and more specifically to a synthesis method for preparing a coating layer using modified PPO as a coating material and a PE diaphragm as a substrate by a non-solvent phase inversion method. Background Art
[0002] In the 1970s, two serious oil crises broke out around the world, making countries realize the disadvantages of over-reliance on fossil energy and begin to actively seek diversification and transformation of their energy structure.
[0003] Against this backdrop, the development of renewable energy and supporting energy storage technologies has become a key breakthrough in alleviating the energy crisis. Lithium-ion batteries, with their unique performance advantages, have gradually become the core solution in the field of electrochemical energy storage. Lithium-ion batteries have significant advantages: First, they have high energy density, allowing them to store more energy in a smaller volume and weight, providing a technical foundation for the development of long-range electric vehicles and promoting a green revolution in the transportation sector. Second, they have long cycle life and low self-discharge rates, which can reduce the frequency of battery replacement and thus reduce resource consumption. However, as battery energy density and charging rates continue to increase, the rate of heat generation within the battery has significantly increased, and thermal runaway has become a key bottleneck restricting their large-scale application.
[0004] Research has shown that traditional polyolefin separators melt and shrink above 130°C, leading to direct contact between the positive and negative electrodes, causing a short circuit, which in turn triggers a thermal runaway chain reaction and is a major cause of battery fires and explosions. This challenge places higher demands on the development of lithium-ion battery separators, such as improved thermal stability, improved electrolyte wettability, and higher ionic conductivity. Clearly, the safety of lithium-ion batteries must be achieved through material innovation and component optimization. Achieving breakthroughs in energy density, safety, and cycle stability is highly dependent on the physical and chemical properties of core components such as electrodes, electrolytes, and separators. Summary of the Invention
[0005] The present invention aims to address the bottleneck issues of poor electrolyte wettability and insufficient thermal stability of existing polyolefin separators (PE / PP) in lithium-ion battery applications, and to provide a preparation method and application of a modified polyphenylene ether (PPO)-coated polyolefin separator. The composite separator comprises: (1) using PPO as a matrix, introducing bromine atoms through a free radical bromination reaction to construct a flame-retardant BPPO precursor; (2) constructing a porous BPPO coating on both sides of the PE base film using a non-solvent phase inversion method to form a BPPO / PE / BPPO sandwich structure; and (3) constructing a cross-linked network in the BPPO coating and introducing highly polar amine (-NH2) and hydroxyl (-OH) functional groups through an in-situ amination reaction with 3-aminopropyltrihydroxysilane.
[0006] To achieve the above object, the present invention adopts the following technical solutions:
[0007] According to the first aspect of the present invention, the present invention provides a preparation method of a modified polyphenylene oxide (PPO) coated polyolefin separator, comprising the following steps:
[0008] A preparation method of a modified polyphenylene oxide (PPO) coated polyolefin separator, characterized by comprising the following steps:
[0009] S1. Bromination treatment: After dissolving PPO in a chlorobenzene solution, an electrophilic substitution reaction is carried out with N-bromosuccinimide under N2 protection, and azobisisobutyronitrile is used as an initiator to prepare brominated polyphenylene oxide (BPPO);
[0010] S2. Preparation of a three-layer composite separator: Using the non-solvent phase inversion method, a casting solution is prepared with N-methylpyrrolidone as a solvent and polyethylene glycol as a pore-forming agent, and a BPPO coating is formed on both sides of the PE separator through a doctor blade coating process, and solidified in a deionized water / absolute ethanol coagulation bath for 24 h;
[0011] S3. Surface functionalization treatment: Through an in-situ amination reaction, the composite separator is immersed in a 3-aminopropyltrihydroxysilane solution to construct a cross-linked structure, and at the same time, amino / hydroxyl polar functional groups are introduced.
[0012] Preferably, in step S1, PPO and a chlorobenzene solution are successively added to a three-necked round-bottom flask and magnetically stirred, azobisisobutyronitrile and N-bromosuccinimide are added, under N2 protection, refluxed with condensation, heated, reacted for 4 h, poured into a methanol solvent to precipitate, the product is cut into pieces and dried to obtain a light yellow flaky solid, marked as BPPO.
[0013] Preferably, in step S1, the N2 gas flow rate is 1 mL / min - 10 mL / min, and the heating temperature is 120 - 135 °C.
[0014] Preferably, in step S2, the base film is a PE or PP separator, the stirring speed is 500 r / min to 1000 r / min, and the stirring temperature is 30 - 45 °C.
[0015] Preferably, in step S3, the cleaning agent is at least one of ethanol, methanol and water, and the drying temperature is 60 - 80 °C.
[0016] Compared with the prior art, the preparation method and application of a modified polyphenylene oxide (PPO) coated polyolefin separator provided by the present invention have at least the following beneficial effects:
[0017] (1) The method provided by the present invention first uses brominated modified PPO to prepare BPPO. Subsequently, the BPPO casting solution is uniformly coated on both sides of the PE base film by the non-solvent phase separation method. Finally, the BPPO-coated separator is immersed in a 3-aminopropyltrihydroxysilane solution to form a cross-linked BPPO coating by in-situ amination, while introducing highly polar amino and hydroxyl groups. The reaction conditions are mild and the preparation process is simple.
[0018] (2) The lithium-ion coated separator prepared by the present invention has a heat shrinkage rate reduced by 50.36% compared to the PE separator under the conditions of 160 °C / 30 min, and at the same time has excellent flame retardant properties; the instantaneous contact angle of the electrolyte is reduced by 76.3% compared to the PE separator. The performance is significantly improved compared to the commercial PE separator. Description of the Drawings
[0019] Figure 1 SEM diagram of Example 1 of the present invention Detailed Embodiments
[0020] To make the technical solutions and advantages of the present invention clearer, the following will, in conjunction with specific embodiments, clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.
[0021] Example 1
[0022] A method for preparing a lithium-ion coated separator using cross-linked brominated modified PPO as a coating material, comprising the following steps:
[0023] (1) Bromination treatment: 5 g of PPO and 60 mL of chlorobenzene solution are successively added to a three-necked round-bottom flask, magnetically stirred at room temperature until completely dissolved, 0.4 g of azobisisobutyronitrile and 9.0 g of N-bromosuccinimide are added, and under N2 protection, it is refluxed by condensation and heated to 135 °C for 6 h. After the reaction is completed, it is poured into an anhydrous ethanol solvent for precipitation, and finally the product is cut into pieces and dried. After cutting, it is placed in a vacuum drying oven and dried at 100 °C for 24 h to finally obtain a light yellow flaky solid, marked as BPPO.
[0024] (2) Construction of BPPO / PE / BPPO sandwich structure: First, take 2.57 g of BPPO and add it to 10 mL of N-methylpyrrolidone solution. After BPPO is completely dissolved, add 0.29 g of polyethylene glycol to the solution. Stir vigorously at 45 °C for 5 h, then centrifuge at 8000 r / min for 25 min to remove air bubbles. Use a 25-μm doctor blade to scrape the casting solution onto a glass plate. Connect PE to the casting solution and perform the same operation on the other side of PE. Finally, immerse the PE membrane in an ethanol coagulation bath, take it out after standing for 24 h, and dry it at 80 °C for 8 h, marked as BPPO / PE-0 membrane.
[0025] (3) Surface functionalization treatment: First, take 2.00 mL of 3-ATS and add it to 10 mL of deionized water, and stir evenly. Immerse the BPPO / PE-0 membranes in 3-aminopropyltrihydroxysilane (150 wt%) solution for 1, 2, 3 h respectively. After taking them out, rinse them repeatedly with anhydrous ethanol. Finally, put them into a vacuum oven and dry them at 80 °C for 8 h to form BPPO / PE-(1-3) membranes. The contact angle of the composite membrane electrolyte is 11.98°, and the thermal shrinkage rate at 160 °C / 30 min is 12.8%.
[0026] Example 2
[0027] (1) Bromination treatment: Add 10 g of PPO and 100 mL of chlorobenzene solution to a three-necked round-bottom flask in sequence, stir magnetically at room temperature until completely dissolved, add 0.5 g of azobisisobutyronitrile and 9.8 g of N-bromosuccinimide, condense and reflux under N2 protection, and heat to 135 °C, react for 4 h. After the reaction is completed, pour it into anhydrous ethanol solvent to precipitate, and finally cut and dry the product. After cutting, place it in a vacuum drying oven and dry it at 100 °C for 24 h to finally obtain a light yellow flaky solid, marked as BPPO.
[0028] (2) Construction of BPPO / PE / BPPO sandwich structure: First, take 3.57 g of BPPO and add it to 20 mL of N-methylpyrrolidone solution. After BPPO is completely dissolved, add 0.58 g of polyethylene glycol to the solution. Stir vigorously at 30 °C for 10 h, then centrifuge at 8000 r / min for 25 min to remove air bubbles. Use a 25-μm doctor blade to scrape the casting solution onto a glass plate. Connect PE to the casting solution and perform the same operation on the other side of PE. Finally, immerse the PE membrane in an ethanol coagulation bath, take it out after standing for 24 h, and dry it at 80 °C for 8 h, marked as BPPO / PE-0 membrane.
[0029] (3) Surface functionalization treatment: First, 4.00 mL of 3-aminopropyltrihydroxysilane was added to 20 mL of deionized water and stirred evenly. The BPPO / PE-0 separator was immersed in 3-aminopropyltrihydroxysilane (20 wt%) solution for 1, 2, and 3 h respectively. After taking it out, it was repeatedly rinsed with absolute ethanol. Finally, it was placed in a vacuum oven and dried at 80 °C for 8 h to form the BPPO / PE-(1-3) separator. The contact angle of the composite separator electrolyte was 18.98°, and the thermal shrinkage rate was 19.8% at 160 °C / 30 min.
[0030] Based on the disclosure and teachings of the above specification, those skilled in the art to which the present invention pertains are also able to make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the above specific embodiments, and any obvious improvements, substitutions, or variations made by those skilled in the art based on the present invention fall within the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.
Claims
1. A preparation method of a polyolefin separator coated with modified polyphenylene oxide (PPO), characterized in that, It includes the following steps: S1. Bromination treatment: After dissolving PPO in a chlorobenzene solution, an electrophilic substitution reaction is carried out with N-bromosuccinimide under N2 protection, and azobisisobutyronitrile is used as an initiator to prepare brominated polyphenylene oxide (BPPO); S2. Preparation of a three-layer composite separator: Using the non-solvent phase inversion method, a casting solution is prepared with N-methylpyrrolidone as the solvent and polyethylene glycol as the pore-forming agent. A BPPO coating is formed on both sides of the PE separator through a doctor blade process and cured in a deionized water / absolute ethanol coagulation bath for 24 h; S3. Surface functionalization treatment: Through an in-situ amination reaction, the composite separator is immersed in a 3-aminopropyltrihydroxysilane (3-ATS) solution to construct a cross-linked structure, and at the same time, amino / hydroxyl polar functional groups are introduced.
2. The preparation method of a polyolefin separator coated with modified polyphenylene oxide (PPO) according to claim 1, characterized in that: In step S1, (PPO) and the chlorobenzene solution are successively added to a three-necked round-bottom flask and magnetically stirred. AIBN and NBS are added, protected by N2, refluxed under condensation, heated, reacted for 4 h, poured into a methanol solvent for precipitation, the product is cut into pieces, dried, and a pale yellow flaky solid is obtained, marked as BPPO.
3. The preparation method of a polyolefin separator coated with modified polyphenylene oxide (PPO) according to claim 1, characterized in that: In step S1, the N2 gas flow rate is 1 mL / min - 10 mL / min, and the heating temperature is 120 - 135 °C.
4. A preparation method of a polyolefin separator coated with modified polyphenylene oxide (PPO) according to claim 1, characterized in that: In step S2, the base film is a PE or PP separator, the stirring speed is 500 r / min - 1000 r / min, and the stirring temperature is 30 - 45 °C.
5. The preparation method of a polyolefin separator coated with modified polyphenylene oxide (PPO) according to claim 1, wherein: In step S3, the cleaning agent is at least one of ethanol, methanol, and water, and the drying temperature is 60 - 80 °C.