Dispersing agent based on modified benzyl resin micelle and preparation method thereof

Abstract

The preparation method comprises the following steps: S1, hydrophilic-hydrophobic bi-component modification reaction: dissolving a styrene-maleic anhydride copolymer, hydrophilic polyethylene glycol monomethyl ether and hydrophobic long-chain alkyl alcohol in butanone according to a ratio, adding a catalyst, stirring, reacting, filtering, washing, and drying to obtain the dispersing agent for the lithium battery diaphragm based on the modified benzyl resin micelle. Performing ester exchange reaction on anhydride bonds of the styrene-maleic anhydride copolymer and polyether hydroxyl and alkyl alcohol hydroxyl respectively to obtain a modified intermediate; s2, neutralization reaction: dropwise adding organic alkali into the modified intermediate, and adjusting the pH value to obtain a modified SMA solution containing carboxylate groups; s3, preparing nano-micelles: dropwise adding the modified SMA solution into deionized water, and stirring to enable the modified SMA solution to be self-assembled to form the nano-micelles, so as to obtain nano-micelle dispersion liquid; and S4, dispersing agent forming: stirring the nano-micelle dispersion liquid to remove butanone so as to obtain the water-based dispersing agent.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of lithium battery separator materials, in particular to a dispersant for lithium battery separators based on modified benzoin resin micelles and a preparation method thereof. BACKGROUND

[0002] Lithium ion batteries are widely used in portable electronic devices, electric tools, electric vehicles and large-scale energy storage systems due to their high energy density and long cycle life. As the core component of the battery, the separator bears the key function of isolating the positive and negative electrodes to prevent internal short circuit, while ensuring efficient transmission of lithium ions. The current mainstream separator adopts polyolefin materials such as polyethylene and polypropylene, but it is prone to thermal shrinkage or even melting at high temperatures, which leads to electrode material migration and abnormal internal temperature rise, seriously threatening the safety performance of the battery. With the popularity of high-energy-density ternary batteries and lithium iron phosphate batteries, ceramic-coated separators have gradually become an inevitable choice to improve the thermal stability of the battery. However, ceramic materials such as alumina and boehmite have a strong hydrophilic property, which easily absorbs moisture from the environment, resulting in excessive water content in the separator, which in turn causes the generation of gas and pressure accumulation in the battery, not only reducing the electrochemical performance, but also inducing unpredictable safety risks.

[0003] In the manufacturing process of ceramic separators, nano-sized ceramic powder needs to be uniformly dispersed in an aqueous medium to form a stable slurry. Due to the high surface energy and weak hydrophilicity of ceramic particles, they are prone to agglomeration, leading to uneven dispersion of the slurry, which ultimately affects the thickness consistency and porosity distribution of the separator. In addition, the high specific surface area of nano-ceramic powder makes it difficult to completely remove water during drying, and the residual water will damage the long-term stability and cycle life of the battery.

[0004] Existing technologies attempt to improve the performance of the slurry by adding dispersants, such as using low-molecular-weight ionic polymer dispersants to improve short-term stability, or using polystyrene-ceramic composites combined with hydrophobic components to reduce water absorption. However, these methods still face significant challenges in practical applications: the interface interaction between the dispersant and the ceramic particles is insufficient, leading to severe settling of the slurry during long-term storage; at the same time, the hydrophilicity of the dispersant cannot effectively inhibit the water absorption of the separator coating, making it difficult to meet the requirements of dispersion stability and low moisture absorption.

[0005] Therefore, there is an urgent need to develop a new dispersant system that can achieve efficient dispersion of ceramic particles, inhibit overnight settling, and significantly reduce the water absorption tendency of the separator coating through molecular structure design. SUMMARY

[0006] The purpose of the present application is to provide a dispersant for lithium battery separators based on modified benzoin resin micelles and a preparation method thereof, which has the technical effects of improving the dispersion stability of ceramic slurry, inhibiting overnight settling and reducing the water absorption of the separator coating.

[0007] The above technical objective of the present application is achieved by the following technical solutions:

[0008] A preparation method of a dispersant for lithium battery separators based on modified benzene puma resin micelles, comprising the following steps:

[0009] S1. Hydrophilic-hydrophobic two-component modification reaction: the styrene maleic anhydride copolymer, hydrophilic polyethylene glycol monomethyl ether and hydrophobic long-chain alkyl alcohol are mixed in a molar ratio of 1: (0.1-1.0): (0.1-1.6), butanone is used as a solvent, p-toluenesulfonic acid or triethylamine is added as a catalyst, and the mixture is stirred at 60-80°C under nitrogen protection for 8-12 h. The anhydride bonds of the styrene maleic anhydride copolymer are subjected to ester exchange reactions with the polyether hydroxyl groups of the hydrophilic polyethylene glycol monomethyl ether and the alkyl alcohol hydroxyl groups of the hydrophobic long-chain alkyl alcohol, respectively. After the reaction is completed, the mixture is cooled to room temperature to obtain a modified intermediate;

[0010] S2. Neutralization reaction: an organic base is added dropwise to the modified intermediate, and the mixture is stirred for 2-4 h to adjust the pH value to 7.5-9.0 to obtain a modified SMA solution containing carboxylate groups;

[0011] S3. Nanomicelle preparation: the modified SMA solution is added dropwise to deionized water at a rate of 1-2 mL / min, and the mixture is stirred at a speed of 1000-2000 rpm for 1-3 h to allow the modified SMA solution to self-assemble into nanomicelles with a particle size of 150-250 nm to obtain a nanomicelle dispersion;

[0012] S4. Dispersant shaping: the nanomicelle dispersion is stirred at a speed of 300-500 rpm for 24-48 h to remove butanone, and an aqueous dispersant with a solid content of 10-40 wt% is obtained.

[0013] Further, in the step S1, the molar content of the maleic anhydride units of the styrene maleic anhydride copolymer is 25%-50%, the molecular weight of the hydrophilic polyethylene glycol monomethyl ether is 400-20000, and the hydrophobic long-chain alkyl alcohol contains a straight-chain alkyl alcohol C 12 -C 18 The solid-liquid ratio of butanone is 1:2-1:5, and the catalyst accounts for 1%-5% of the total raw material mass.

[0014] Further, in the step S2, the organic base is one of trimethylamine, triethylamine, triethanolamine, N,N-diethyl ethanolamine or AMP-95.

[0015] A dispersant for lithium battery separators, which has a nanomicelle structure comprising a hydrophobic core and a hydrophilic shell. The hydrophobic core is composed of styrene units and long-chain alkyl ester groups, and the hydrophilic shell is composed of polyethylene glycol segments and carboxylate groups.

[0016] Further, the nanomicelles are anchored on the surface of ceramic particles by hydrophobic adsorption, and the dispersion stability is maintained by the synergistic effect of steric hindrance and electrostatic repulsion.

[0017] In summary, the present application has the following advantages:

[0018] 1. Excellent dispersion stability: synergistic effect of steric hindrance, electrostatic repulsion and hydrophobic adsorption

[0019] In the two-component modified SMA nanomicelles, the polyethylene glycol segment provides hydrophilicity and steric hindrance, the carboxylate provides hydrophilicity and electrostatic repulsion, and the styrene and long-chain alkyl provide hydrophobicity. Under the synergistic effect of steric hindrance, electrostatic repulsion and hydrophobic adsorption, ceramic particles can be uniformly wrapped, forming a "anchoring-stable" dual effect, which significantly improves the dispersion uniformity of ceramic slurry, narrows the particle size distribution (reduces large agglomerates), and makes the pore size distribution of the coating film more regular.

[0020] 2. Overnight sedimentation of slurry is greatly improved: the effect of "three-dimensional stabilization system" of nanomicelles

[0021] A stable dispersion system is constructed by "nanomicellization", and ceramic particles are wrapped in the "core-shell" structure of micelles (hydrophobic core adsorbs particles, hydrophilic shell contacts with water), which is equivalent to providing "micro carrying units" for particles, reducing the sedimentation rate of particles directly affected by gravity, and fundamentally delaying sedimentation.

[0022] The "hydration layer" formed by the polyethylene glycol segment on the surface of the micelles has uniform thickness and is not easy to break, so that the dispersion distance between particles can be maintained even after a long time (12-24h) of standing, avoiding the aggregation and sedimentation of particles due to the desorption of dispersants.

[0023] Neutralization to weak alkaline can inhibit the protonation of residual carboxyl groups in SMA molecules, avoid the decrease of electrostatic repulsion caused by the reduction of carboxylate groups, and further prolong the storage life of the slurry.

[0024] 3. The water absorption of the separator coating is significantly reduced:

[0025] The hydrophobic dominant effect of styrene and long-chain alkyl: forming a "hydrophobic barrier" on the surface or inside of the ceramic coating, the hydrophobic groups are limitedly exposed on the surface of the coating, hindering the contact between water molecules in the air and the hydrophilic sites (such as ceramic hydroxyl groups and unmodified carboxyl groups) of the coating; in addition, the hydrophobic groups are distributed in the coating, reducing the penetration channels of water molecules.

[0026] The "hydrophilic offset" optimization of polyether segments: although the single-terminated polyether segment is a hydrophilic segment, the hydrophilic part thereof is mainly distributed in the interior of the coating rather than the surface of the coating after modification, and the hydrophobic effect of the long-chain alkyl group can offset the hydrophilicity of the polyether, avoiding the overall hydrophilicity of the coating;

[0027] Weak base reduces hydrophilic group residues: the neutralization reaction can convert most of the maleic anhydride in the SMA into carboxylate (which is less hydrophilic than the free carboxyl group), reducing the number of "strongly hydrophilic sites" in the coating and further reducing the water absorption driving force.

[0028] 4. High controllability of the process, suitable for large-scale production:

[0029] The chemical modification of phenomer resin and the preparation process of micelles do not require high temperature and high pressure, and the conditions are mild and the cost is controllable, which is easy to industrialize and scale up production. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a flow chart of the preparation method of the dispersant for lithium battery separators described in the present application.

[0031] Figure 2 is the infrared spectrum of the dispersant based on modified phenomer resin micelles described in the present application. DETAILED DESCRIPTION

[0032] In order to make the technical means, creative features, purposes and effects realized by the present application easy to understand, the present application will be further described below in combination with the drawings and specific embodiments.

[0033] Referring to Figure 1 The present application provides a preparation method of a dispersant for lithium battery separators based on modified phenomer resin micelles, which comprises the following steps:

[0034] S1. Hydrophilic-hydrophobic two-component modification reaction: the styrene maleic anhydride copolymer, hydrophilic polyethylene glycol monomethyl ether and hydrophobic long-chain alkyl alcohol are mixed in a molar ratio of 1:(0.1-1.0):(0.1-1.6), butanone is used as the solvent, p-toluenesulfonic acid or triethylamine is added as the catalyst, and the mixture is stirred at 60-80°C under nitrogen protection for 8-12h, so that the anhydride bonds of the styrene maleic anhydride copolymer respectively undergo ester exchange reactions with the polyether hydroxyl groups of the hydrophilic polyethylene glycol monomethyl ether and the alkyl alcohol hydroxyl groups of the hydrophobic long-chain alkyl alcohol, and then the mixture is cooled to room temperature to obtain a modified intermediate;

[0035] S2. Neutralization reaction: an organic base is added dropwise to the modified intermediate, and stirred for 2-4h to adjust the pH value to 7.5-9.0, to obtain a modified SMA solution containing carboxylate groups;

[0036] S3. Nanomicelle preparation: The modified SMA solution is added dropwise into deionized water at a rate of 1-2 mL / min, and stirred at a speed of 1000-2000 rpm for 1-3 h, so that the modified SMA solution self-assembles to form nanomicelles with a particle size of 150-250 nm, to obtain a nanomicelle dispersion;

[0037] S4. Dispersion agent shaping: The nanomicelle dispersion is stirred at a speed of 300-500 rpm for 24-48 h to remove butanone, to obtain an aqueous dispersion agent with a solid content of 10-40 wt%.

[0038] In practical applications, the styrene maleic anhydride copolymer can be understood as a high molecular material with anhydride bond structure, and the anhydride bond can introduce different functional groups through chemical reaction, such as esterification reaction with polyol compounds to achieve functional modification. Further, the selection of hydrophilic polyethylene glycol monomethyl ether can be adjusted based on its molecular weight range, such as using low molecular weight polyethylene glycol monomethyl ether with a molecular weight of 400, or ultrahigh molecular weight polyethylene glycol monomethyl ether with a molecular weight of 20000, to meet the needs of different application scenarios. The specific implementation of the hydrophobic long-chain alkyl alcohol can include straight-chain or branched-chain alkyl alcohol, which mainly provides hydrophobic properties to enhance the interfacial interaction with ceramic particles.

[0039] The innovation of the present application is to construct a modified intermediate with specific amphiphilic structure through hydrophilic-hydrophobic two-component modification reaction, and to prepare a particle size controllable dispersion agent by combining nanomicelle self-assembly technology. Compared with the prior art, by introducing the synergistic effect of hydrophilic and hydrophobic functional groups, the dispersion uniformity and long-term stability of the ceramic slurry are significantly improved, and by removing the organic solvent, the water absorption tendency of the coating is reduced, thereby effectively solving the problems of uneven dispersion, overnight settling and high water absorption of the ceramic slurry for lithium battery separators.

[0040] The working principle of the present application is as follows:

[0041] Through hydrophilic-hydrophobic two-component modification reaction, the styrene maleic anhydride copolymer, hydrophilic polyethylene glycol monomethyl ether and hydrophobic long-chain alkyl alcohol are proportioned at a specific molar ratio, and ester exchange reaction is carried out in butanone as solvent under the action of catalyst in a nitrogen protection environment. In this process, the anhydride bond of the styrene maleic anhydride copolymer reacts with the polyether hydroxyl group of the hydrophilic polyethylene glycol monomethyl ether and the alkyl alcohol hydroxyl group of the hydrophobic long-chain alkyl alcohol, respectively, to generate a modified intermediate with amphiphilic properties. The hydrophobic part of the intermediate can enhance the interfacial interaction with ceramic particles, while the hydrophilic part improves its compatibility in aqueous phase, thereby significantly improving the initial dispersion effect of the slurry.

[0042] Further, an organic base is added dropwise to the modified intermediate and the pH value is adjusted to 7.5-9.0, so that the intermediate is converted into a modified SMA solution containing a carboxylate group. The introduction of the carboxylate group increases the ionization degree and hydrophilicity of the molecule, strengthens the electrostatic repulsion effect, effectively inhibits the short-term aggregation phenomenon of ceramic particles, and maintains the instant stability of the slurry.

[0043] Specifically, the modified SMA solution is added dropwise to deionized water at a rate of 1-2 mL / min and stirred at a speed of 1000-2000 rpm for 1-3 h, so that it self-assembles to form nanomicelles with a particle size of 150-250 nm. Nanomicelles in this size range can uniformly wrap ceramic particles, providing a steric hindrance stabilization mechanism, thereby significantly alleviating the overnight settling problem of the slurry. In addition, the structural properties of the nanomicelles also enhance their adsorption capacity on the surface of ceramic particles, further improving the dispersion effect.

[0044] Finally, the nanomicelle dispersion is stirred at a speed of 300-500 rpm for 24-48 h to remove residual butanone, obtaining an aqueous dispersant with a solid content of 10-40 wt%. The complete removal of organic solvents reduces the water absorption tendency of the coating, and the moderate solid content ensures the effectiveness of the dispersant in practical applications. Thus, the above steps work synergistically to construct an aqueous dispersant with a specific structure, solving the problems of uneven dispersion, overnight settling and high water absorption of the ceramic slurry for lithium battery separators.

[0045] The present application further proposes that the maleic anhydride unit mole content of the styrene maleic anhydride copolymer in step S1 is 25%-50%, the molecular weight of the hydrophilic polyethylene glycol monomethyl ether is 400-20000, the hydrophobic long-chain alkyl alcohol contains a linear alkyl alcohol C 12 -C 18 , the solid-liquid ratio of butanone is 1:2-1:5, and the catalyst accounts for 1%-5% of the total raw material mass.

[0046] Specifically, the maleic anhydride unit mole content of the styrene maleic anhydride copolymer refers to the proportion of maleic anhydride units in the copolymer, aiming to ensure a moderate number of anhydride bonds to achieve sufficient transesterification. The molecular weight of the hydrophilic polyethylene glycol monomethyl ether refers to the average molecular weight of the polymer segment, aiming to provide sufficient hydrophilicity to form a stable micelle shell, while avoiding steric hindrance effects that hinder the self-assembly process. The hydrophobic long-chain alkyl alcohol is defined as C 12 -C 18The linear alkyl alcohol has a moderate carbon chain length, which can strengthen the construction ability of the hydrophobic core, and enable the micelles to be firmly anchored on the surface of the ceramic particles through hydrophobic interaction. The solid-liquid ratio of butanone refers to the mass-volume ratio of solid raw materials to solvent, and aims to promote the uniform progress of the ester exchange reaction and provide a suitable medium environment for subsequent solvent removal and micelle self-assembly. The proportion of the catalyst in the total raw materials refers to the percentage of the catalyst dosage in the total mass of the reaction system, and aims to accelerate the reaction rate of the anhydride bond and the hydroxyl group, while avoiding excessive initiation of side reactions or residual impurities.

[0047] Specifically, the above technical solution realizes the efficiency of the modification reaction and the controllability of the product structure by accurately limiting the key parameters. The maleic anhydride unit molar content in the range of 25%-50% can balance the number of anhydride bonds, avoid the problems of insufficient grafting or decreased resin thermal stability, thereby ensuring the reasonable distribution of carboxylic acid groups and ester bonds in the modified intermediate. The molecular weight of the hydrophilic polyethylene glycol monomethyl ether between 400-20000 can provide sufficient hydrophilicity, and will not hinder the self-assembly process due to excessive molecular weight, ensuring that the micelles effectively play a steric hindrance stabilizing role in the dispersion system. The hydrophobic long-chain alkyl alcohol is limited to C 12 -C 18 The linear alkyl alcohol has a moderate carbon chain length, which can strengthen the construction ability of the hydrophobic core, and enable the micelles to be firmly anchored on the surface of the ceramic particles through hydrophobic interaction. The solid-liquid ratio of butanone refers to the mass-volume ratio of solid raw materials to solvent, and aims to promote the uniform progress of the ester exchange reaction and provide a suitable medium environment for subsequent solvent removal and micelle self-assembly. The proportion of the catalyst in the total raw materials refers to the percentage of the catalyst dosage in the total mass of the reaction system, and aims to accelerate the reaction rate of the anhydride bond and the hydroxyl group, while avoiding excessive initiation of side reactions or residual impurities, ensuring the purity and consistency of the modified intermediate, and ultimately improving the comprehensive performance of the dispersant on the dispersion stability of the ceramic slurry and the water absorption of the membrane coating.

[0048] Through the above technical solution, if the maleic anhydride unit content of the styrene maleic anhydride copolymer, the molecular weight of the hydrophilic polyethylene glycol monomethyl ether, the carbon chain length of the hydrophobic long-chain alkyl alcohol, the solid-liquid ratio of butanone or the proportion of the catalyst are not properly selected, the problems of incomplete ester exchange reaction and unstable structure of the modified intermediate can be solved, thereby ensuring the formation quality of the nanomicelles, enhancing the anchoring ability of the dispersant on the surface of the ceramic particles, and effectively improving the slurry dispersion uniformity and reducing the water absorption of the membrane coating.

[0049] The present application further proposes that the organic base in step S2 is one of trimethylamine, triethylamine, triethanolamine, N,N-diethyl ethanolamine or AMP-95.

[0050] Specifically, the organic base refers to an organic compound with basic properties, which can be achieved by using small molecule tertiary amine substances such as trimethylamine and triethylamine. The purpose of introducing these substances is to provide moderate basic strength to ensure efficient and controllable neutralization reaction process. In addition, triethanolamine and N,N-diethyl ethanolamine contain hydroxyl structures, which can enhance the hydrophilicity of the solution, thereby helping to stabilize the hydrophilic shell of the modified SMA molecule. AMP-95, as an amino alcohol compound, can provide buffering effect to maintain the stability of pH value and prevent micelles from aggregating due to pH fluctuation during formation.

[0051] The above technical solution optimizes the conditions of the neutralization reaction by limiting the specific type of organic base. For example, trimethylamine and triethylamine, as small molecule tertiary amines, are easy to diffuse and quickly participate in the reaction, promoting the conversion of carboxylate groups to carboxylate salts, and their volatility facilitates subsequent removal of solvents without leaving residues. Triethanolamine and N,N-diethyl ethanolamine enhance the hydrophilicity of the solution due to their hydroxyl structures, which help to stabilize the hydrophilic shell of the modified SMA molecule. The buffering properties of AMP-95 effectively avoid sharp fluctuations in pH value, thereby ensuring uniform dispersion of nanomicelles during self-assembly. The selection of such organic bases not only improves the uniformity and stability of the modified SMA solution, but also lays the foundation for subsequent self-assembly of nanomicelles, ultimately improving the dispersion stability of the dispersant for ceramic particles and reducing the water absorption of the separator coating.

[0052] Through the above technical solution, the problem of unstable neutralization reaction efficiency and inaccurate pH adjustment caused by the unqualified type of organic base is solved, thereby improving the dispersion performance of the nanomicelle dispersion liquid, reducing the water absorption of the separator coating, and improving the comprehensive performance and safety of the lithium ion battery.

[0053] Referring to Figure 2 The embodiments of the present application also disclose a dispersant for lithium battery separators, which is a nanomicelle structure containing a hydrophobic core and a hydrophilic shell. The hydrophobic core is composed of styrene units and long-chain alkyl ester groups, and the hydrophilic shell is composed of polyethylene glycol segments and carboxylate groups.

[0054] The core innovation of the present application is that by combining the hydrophobic core with the hydrophilic shell in a specific way and further introducing the design concept of nanomicelles, the dispersion stability of the ceramic slurry is significantly improved and the water absorption of the coating is reduced. Specifically, the styrene units in the hydrophobic core provide basic hydrophobicity, while the long-chain alkyl ester groups enhance the hydrophobic interaction with the surface of the ceramic particles, ensuring that the dispersant can be firmly anchored on the particle surface, preventing uneven dispersion of the slurry and overnight settling problems; at the same time, the polyethylene glycol segments in the hydrophilic shell hinder the approach of particles through steric hindrance effect, and the carboxylate groups provide electrostatic repulsion, both of which maintain the long-term dispersion stability of the slurry. In addition, the composition of the hydrophilic shell optimizes the balance of hydrophilic and hydrophobic levels at the interface, reducing the absorption of water by the coating, thereby effectively solving the problems of uneven dispersion of ceramic slurry, overnight settling and high water absorption of lithium battery separator.

[0055] The present application further proposes that the nanomicelles are anchored on the surface of the ceramic particles through hydrophobic adsorption, and the dispersion stability is maintained through the synergistic effect of steric hindrance and electrostatic repulsion.

[0056] In practical applications, nanomicelles refer to a kind of polymer nanoparticles with core-shell structure, which can be formed by self-assembly. Hydrophobic adsorption refers to the process of forming strong hydrophobic interaction between the non-polar characteristics of styrene units and long-chain alkyl ester groups in the hydrophobic core of nanomicelles and the weakly hydrophilic region of the surface of ceramic particles, which aims to ensure that the dispersant is firmly attached to the particle surface to avoid falling off during slurry preparation or standing. Steric hindrance refers to the high molecular chain steric hindrance effect produced by polyethylene glycol segments in the hydrophilic shell, which aims to inhibit direct contact between particles through physical barriers. Electrostatic repulsion refers to the repulsive force generated by the surface charge formed after the ionization of carboxylate groups, which aims to further prevent particle aggregation through repulsion between charges.

[0057] Specifically, this scheme systematically solves the core problem of insufficient dispersion stability by precisely designing the interface interaction mechanism of nanomicelles and ceramic particles. Hydrophobic adsorption provides a basic anchor point for the dispersant, ensuring that it can be firmly attached to the surface of the ceramic particles, thereby effectively resisting the risk of falling off during slurry preparation or standing. Steric hindrance and electrostatic repulsion work together to form a multidimensional repulsive force, effectively inhibiting the agglomeration phenomenon caused by van der Waals attraction between particles. Especially under overnight standing conditions, this multidimensional mechanism can significantly maintain the uniformity of the slurry, reduce the risk of settling, and reduce the tendency of the coating to absorb water. In addition, the above dispersant is prepared into a polymer nanomicelle by chemical modification of p-phenylformaldehyde resin, further improving the dispersion effect of the slurry and the performance of the separator coating, ultimately achieving the improvement of the integrity of the separator structure and the safety of the battery.

[0058] In summary, by the technical scheme, the problem of insufficient interface bonding force of nanomicelles and ceramic particles is solved, and the dispersion stability of the slurry and the comprehensive performance of the separator are significantly improved through the multi-dimensional action mechanism, thereby providing reliable guarantee for the safety and cycle performance of the lithium ion battery.

[0059] The application will be further described in detail below with reference to specific examples.

[0060] Example 1

[0061] (1) A 1L four-necked round-bottom flask equipped with a reflux condenser and a stirrer was charged with 40g of phenomas resin (styrene: maleic anhydride = 3:1), 100g of PEG1000, 2.5g of n-dodecanol, 520mg of triethylamine, 250g of butanone as a solvent, and nitrogen was blown for 15min to remove oxygen. The flask was placed in a constant-temperature oil bath, heated to 65℃, and constant-temperature stirring was performed for 8h. After cooling to room temperature, a modified phenomas resin solution was obtained.

[0062] (2) Triethylamine was added to the modified phenomas resin solution, and stirring was performed for 2h. The pH of the system was adjusted to 7.5-9.0.

[0063] (3) The neutralized modified SMA solution was slowly added to 500g of deionized water at a speed of 1000-2000rpm, and the dropping speed was 1-2mL / min. Stirring was performed for 3h to obtain a nanomicelle dispersion liquid.

[0064] (4) The nanomicelle dispersion liquid was continuously stirred at 300rpm (300-500rpm) for 24-48h to volatilize butanone, and a final aqueous dispersant was obtained.

[0065] Example 2

[0066] (1) A 1L four-necked round-bottom flask equipped with a reflux condenser and a stirrer was charged with 40g of phenomas resin (styrene: maleic anhydride = 2:1), 100g of PEG1000, 5g of n-dodecanol, 674mg of triethylamine, 300g of butanone as a solvent, and nitrogen was blown for 15min to remove oxygen. The flask was placed in a constant-temperature oil bath, heated to 65℃, and constant-temperature stirring was performed for 8h. After cooling to room temperature, a modified phenomas resin solution was obtained.

[0067] (2) Triethylamine was added to the modified phenomas resin solution, and stirring was performed for 2h. The pH of the system was adjusted to 7.5-9.0.

[0068] (3) The neutralized modified SMA solution was slowly added to 500g of deionized water at a speed of 1000-2000rpm, and the dropping speed was 1-2mL / min. Stirring was performed for 3h to obtain a nanomicelle dispersion liquid.

[0069] (4) Continue to stir the above nanomicellar dispersion at 300 rpm (300-500 rpm) for 24-48 h to remove butanone by volatilization to obtain the final aqueous dispersant.

[0070] Example Three

[0071] (1) In a 1 L four-necked round bottom flask equipped with a reflux condenser and a stirrer, 40 g of phenomer resin (styrene: maleic anhydride = 1:1), 160 g of PEG1000, 7.44 g of n-dodecanol, 1.1 g of triethylamine were sequentially added, 400 g of butanone was added as a solvent, nitrogen was bubbled for 15 min to remove oxygen, the flask was placed in a constant temperature oil bath, heated to 65 °C, constant temperature stirring reaction for 8 h, and then cooled to room temperature to obtain a modified phenomer resin solution.

[0072] (2) Triethylamine was added to the above modified phenomer resin solution, stirred for 2 h, and the pH of the system was adjusted to 7.5-9.0.

[0073] (3) The neutralized modified SMA solution was slowly added to 500 g of deionized water at a speed of 1000-2000 rpm, the dropping speed was 1-2 mL / min, and the stirring time was 3 h to obtain a nanomicellar dispersion.

[0074] (4) Continue to stir the above nanomicellar dispersion at 300 rpm (300-500 rpm) for 24-48 h to remove butanone by volatilization to obtain the final aqueous dispersant.

[0075] Example Four

[0076] (1) In a 1 L four-necked round bottom flask equipped with a reflux condenser and a stirrer, 40 g of phenomer resin (styrene: maleic anhydride = 1:1), 160 g of PEG1000, 7.44 g of n-dodecanol, 1.1 g of triethylamine were sequentially added, 400 g of butanone was added as a solvent, nitrogen was bubbled for 15 min to remove oxygen, the flask was placed in a constant temperature oil bath, heated to 65 °C, constant temperature stirring reaction for 8 h, and then cooled to room temperature to obtain a modified phenomer resin solution.

[0077] (2) Triethylamine was added to the above modified phenomer resin solution, stirred for 2 h, and the pH of the system was adjusted to 7.5-9.0.

[0078] (3) The neutralized modified SMA solution was slowly added to 500 g of deionized water at a speed of 1000-2000 rpm, the dropping speed was 1-2 mL / min, and the stirring time was 3 h to obtain a nanomicellar dispersion.

[0079] (4) Continue to stir the above nanomicellar dispersion at 300 rpm (300-500 rpm) for 24-48 h to remove butanone by volatilization to obtain the final aqueous dispersant.

[0080] Example Five

[0081] (1) In a 1L four-necked round bottom flask equipped with a reflux condenser and a stirrer, 40g of phenomas resin (styrene: maleic anhydride = 3:1), 180g of PEG2000, 2.5g of n-dodecanol, 520mg of triethylamine were sequentially added, 300g of butanone was added as a solvent, nitrogen was bubbled for 15min to remove oxygen, the flask was placed in a constant temperature oil bath, the temperature was raised to 65°C, constant temperature stirring was carried out for 8h, and then the temperature was lowered to room temperature to obtain a modified phenomas resin solution.

[0082] (2) Triethylamine was added to the above modified phenomas resin solution, stirred for 2h, and the pH of the system was adjusted to 7.5-9.0.

[0083] (3) The neutralized modified SMA solution was slowly added to 500g of deionized water at a speed of 1000-2000rpm, the dropping speed was 1-2mL / min, and stirring was carried out for 3h to obtain a nanomicelle dispersion liquid.

[0084] (4) The above nanomicelle dispersion liquid was continuously stirred at 300rpm (300-500rpm) for 24-48h to volatilize and remove butanone to obtain a final aqueous dispersant.

[0085] Example Six

[0086] (1) In a 1L four-necked round bottom flask equipped with a reflux condenser and a stirrer, 40g of phenomas resin (styrene: maleic anhydride = 3:1), 180g of PEG2000, 2.5g of n-dodecanol, 520mg of triethylamine were sequentially added, 300g of butanone was added as a solvent, nitrogen was bubbled for 15min to remove oxygen, the flask was placed in a constant temperature oil bath, the temperature was raised to 65°C, constant temperature stirring was carried out for 8h, and then the temperature was lowered to room temperature to obtain a modified phenomas resin solution.

[0087] (2) Triethylamine was added to the above modified phenomas resin solution, stirred for 2h, and the pH of the system was adjusted to 7.5-9.0.

[0088] (3) The neutralized modified SMA solution was slowly added to 500g of deionized water at a speed of 1000-2000rpm, the dropping speed was 1-2mL / min, and stirring was carried out for 3h to obtain a nanomicelle dispersion liquid.

[0089] (4) The above nanomicelle dispersion liquid was continuously stirred at 300rpm (300-500rpm) for 24-48h to volatilize and remove butanone to obtain a final aqueous dispersant.

[0090] Example Seven

[0091] (1) In a 1L four-necked round flask equipped with a reflux condenser, a stirrer, 40g of phenomer resin (styrene: maleic anhydride = 3:1), 164g of PEG2000, 2.7g of n-octadecanol, 520mg of triethylamine were sequentially added, 300g of butanone was added as a solvent, nitrogen was bubbled for 15min to remove oxygen, the flask was placed in a constant temperature oil bath, the temperature was raised to 65°C, constant temperature stirring was carried out for 8h, and then the temperature was lowered to room temperature to obtain a modified phenomer resin solution.

[0092] (3) The neutralized modified SMA solution was slowly added to 500g of deionized water at a speed of 1000-2000rpm, the dropping speed was 1-2mL / min, and stirring was carried out for 3h to obtain a nanomicelle dispersion liquid.

[0093] (4) The nanomicelle dispersion liquid was continuously stirred at 300rpm (300-500rpm) for 24-48h to volatilize butanone, and a final aqueous dispersant was obtained.

[0094] Example Eight

[0095] (1) In a 1L four-necked round flask equipped with a reflux condenser, a stirrer, 40g of phenomer resin (styrene: maleic anhydride = 3:1), 164g of PEG2000, 2.7g of n-octadecanol, 520mg of triethylamine were sequentially added, 300g of butanone was added as a solvent, nitrogen was bubbled for 15min to remove oxygen, the flask was placed in a constant temperature oil bath, the temperature was raised to 65°C, constant temperature stirring was carried out for 8h, and then the temperature was lowered to room temperature to obtain a modified phenomer resin solution.

[0096] (2) Triethylamine was added to the above modified phenomer resin solution, stirring was carried out for 2h, and the pH of the system was adjusted to 7.5-9.0;

[0097] (3) The neutralized modified SMA solution was slowly added to 500g of deionized water at a speed of 1000-2000rpm, the dropping speed was 1-2mL / min, and stirring was carried out for 3h to obtain a nanomicelle dispersion liquid.

[0098] (4) The nanomicelle dispersion liquid was continuously stirred at 300rpm (300-500rpm) for 24-48h to volatilize butanone, and a final aqueous dispersant was obtained.

[0099] Example Nine

[0100] (1) In a 1L four-necked round bottom flask equipped with a reflux condenser, a stirrer, 40g of phenomas resin (styrene: maleic anhydride = 3:1), 100g of PEG2000, 9.3g of n-dodecanol, 520mg of triethylamine were sequentially added, 300g of butanone was added as a solvent, nitrogen was blown for 15min to remove oxygen, the flask was placed in a constant temperature oil bath, heated to 65℃, constant temperature stirring was carried out for 8h, and then the temperature was lowered to room temperature to obtain a modified phenomas resin solution.

[0101] (2) Triethylamine was added to the above modified phenomas resin solution, stirred for 2h, and the pH of the system was adjusted to 7.5-9.0.

[0102] (3) The neutralized modified SMA solution was slowly added to 500g of deionized water at a speed of 1000-2000rpm, the dropping speed was 1-2mL / min, and stirring was carried out for 3h to obtain a nanomicelle dispersion.

[0103] (4) The above nanomicelle dispersion was continuously stirred at 300rpm (300-500rpm) for 24-48h to volatilize butanone, and finally an aqueous dispersant was obtained.

[0104] Table 1: Dispersion effect of each example on alumina and boehmite

[0105]

[0106] Table 2: Moisture comparison of coating films of each example

[0107] Moisture out of machine Moisture in oven (ppm) Comparative Example 980 700 Example Four 1155 655 Example Five 935 630 Example Six 1325 710 Example Seven 1000 750 Example Eight 915 625

[0108] As can be seen from the above examples, the application not only solves the problem of insufficient interfacial bonding force of nanomicelles and ceramic particles, but also significantly improves the dispersion stability of the slurry and the comprehensive performance of the separator through a multi-dimensional action mechanism, thereby providing reliable protection for the safety and cycle performance of lithium ion batteries.

[0109] In this document, the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inner", "outer", "vertical", "horizontal" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of expressing the technical solution clearly and conveniently, and therefore cannot be understood as a limitation on the application.

[0110] In this document, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, in addition to including the listed elements, other elements not explicitly listed can also be included.

[0111] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application. Various changes and improvements can be made to the present application without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A process for the preparation of a dispersant based on modified benzoin resin micelles for lithium battery separators, characterized by, The method comprises the following steps: S1. Hydrophilic-hydrophobic dual-component modification reaction: a styrene-maleic anhydride copolymer, a hydrophilic polyethylene glycol monomethyl ether and a hydrophobic long-chain alkyl alcohol are mixed at a molar ratio of 1: (0.1-1.0): (0.1-1.6), butanone is used as a solvent, p-toluenesulfonic acid or triethylamine is added as a catalyst, and the mixture is stirred at 60-80°C under nitrogen protection for 8-12h, so that the anhydride bonds of the styrene-maleic anhydride copolymer undergo ester exchange reactions with the polyether hydroxyl groups of the hydrophilic polyethylene glycol monomethyl ether and the alkyl alcohol hydroxyl groups of the hydrophobic long-chain alkyl alcohol, respectively, and after the reaction is completed, the mixture is cooled to room temperature to obtain a modified intermediate; S2. Neutralization reaction: an organic base is added dropwise to the modified intermediate, and stirred for 2-4h to adjust the pH value to 7.5-9.0 to obtain a modified SMA solution containing a carboxylate group; S3. Nanomicelle preparation: the modified SMA solution is added dropwise to deionized water at a rate of 1-2mL / min, and stirred at a speed of 1000-2000rpm for 1-3h to allow the modified SMA solution to self-assemble into nanomicelles with a particle size of 150-250nm, thereby obtaining a nanomicelle dispersion; S4. Dispersion agent shaping: the nanomicelle dispersion is stirred at a speed of 300-500rpm for 24-48h to remove butanone, thereby obtaining an aqueous dispersion agent with a solid content of 10-40wt%.

2. The method for preparing a dispersant for a lithium battery separator based on modified benzoin resin micelles according to claim 1, characterized by, The maleic anhydride unit molar content of the styrene maleic anhydride copolymer in the step S1 is 25%-50%, the molecular weight of the hydrophilic polyethylene glycol monomethyl ether is 400-20000, the hydrophobic long-chain alkyl alcohol contains a linear alkyl alcohol C with 12 to 18 carbon atoms 12 -C 18 , the solid-liquid ratio of butanone is 1:2-1:5, and the catalyst accounts for 1%-5% of the total raw material mass.

3. The method for preparing a dispersant for a lithium battery separator based on modified benzoin resin micelles according to claim 1, characterized by, The organic base in step S2 is one of trimethylamine, triethylamine, triethanolamine, N,N-diethyl ethanolamine or AMP-95.

4. A dispersant for a lithium battery separator, which is produced by the production method described in any one of claims 1 to 3, characterized by The dispersion agent is a nanomicelle structure comprising a hydrophobic core and a hydrophilic shell; the hydrophobic core is composed of styrene units and long-chain alkyl ester groups, and the hydrophilic shell is composed of polyethylene glycol segments and carboxylate groups.

5. The dispersant for lithium battery separators according to claim 4, characterized by The nanomicelles are anchored on the surface of ceramic particles through hydrophobic adsorption, and the dispersion stability is maintained through the synergistic effect of steric hindrance and electrostatic repulsion.

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