A high-wetting modified ceramic slurry, a preparation method thereof and application thereof in the field of battery separators

Abstract

The application discloses a kind of high infiltration modified ceramic slurry and its preparation method and battery separator application, it is related to battery separator material technical field.The slurry includes the following mass parts components: interface ceramic microparticle 25-38 parts, inorganic heat-resistant filler 10-18 parts, water-based binder 2-5 parts, dispersant 0.2-0.8 parts, thickening agent 0.3-1.0 parts, non-ionic wetting agent 0.1-0.5 parts, defoaming agent 0.05-0.20 parts and deionized water 80-130 parts.The interface ceramic microparticle is boehmite as core, and the particle surface is connected polyether bridging structure and hydroxyl sulfobetaine group by silane grafting layer.Said slurry is prepared by dispersing, bead milling, defoaming and filtering each component, can improve slurry dispersion stability, base film coating spreadability, electrolyte wettability, separator air permeability and thermal dimensional stability.

Description

Technical Field

[0001] This invention relates to the field of ceramic coating materials for battery separators, specifically to a highly wettable modified ceramic slurry, its preparation method, and its application in the field of battery separators. Background Technology

[0002] Lithium-ion and sodium-ion batteries typically use polyethylene, polypropylene, or composite microporous membranes as the separator substrate. These polyolefin-based membranes possess good mechanical properties and chemical stability, but their low surface energy limits their affinity for aqueous ceramic slurries and carbonate electrolytes. During coating, issues such as edge shrinkage, localized exposure, or uneven spreading can easily occur. After electrolyte injection, slow wetting speed and insufficient localized wetting may also exist. Using heat-resistant particles such as boehmite and alumina to form a ceramic coating can improve the separator's heat resistance, dimensional stability, and electrolyte retention capacity; however, the coating performance is still affected by the particle surface condition, pore structure, and coating uniformity. Localized accumulation or excessive density of the ceramic layer can prolong the electrolyte wetting time along the thickness direction, increasing ion transport resistance. Existing aqueous ceramic slurries often directly compound unmodified inorganic particles with dispersants, binders, and wetting agents. Inorganic particles have a large specific surface area, and the interparticle forces easily cause agglomeration, flocculation, and sedimentation. Viscosity changes may occur in the slurry during storage and cyclic coating, leading to coating thickness fluctuations, uneven particle distribution, and filter clogging. While added surfactants can reduce the surface tension of the slurry, their effect is affected by the amount added, the order of addition, and the adsorption state. Insufficient addition makes it difficult to achieve sufficient wetting, while a high amount of free components may lead to increased foaming, particle re-aggregation, and changes in coating pore structure. Simply increasing the amount of wetting agent or binder can also easily alter the rheological state of the slurry and the pore structure after drying. Current technology still requires a modified ceramic slurry with stable particle interfaces, capable of maintaining uniform dispersion in the aqueous phase, and providing continuous wetting ability of the ceramic coating to the electrolyte. Summary of the Invention

[0003] The purpose of this invention is to address the problems in existing technologies, such as insufficient wetting and spreading ability of water-based ceramic slurries for polyolefin microporous membranes in battery separators, easy agglomeration and sedimentation of inorganic ceramic particles and poor slurry dispersion stability, easy free migration of added wetting agents making it difficult to maintain a stable interfacial wetting effect, and difficulty in simultaneously achieving uniformity, pore structure, electrolyte wetting performance and ion transport performance of ceramic coatings. This invention provides a highly wettable modified ceramic slurry with uniform ceramic particle dispersion, good slurry stability, strong coating adaptability, and good electrolyte wetting ability and heat resistance of the resulting ceramic coating, along with its preparation method and its application in the field of battery separators.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a highly wettable modified ceramic slurry, composed of the following components in parts by weight: 25-38 parts of interfacial ceramic microparticles, 10-18 parts of inorganic heat-resistant filler, 2-5 parts of water-based binder, 0.2-0.8 parts of dispersant, 0.3-1.0 parts of thickener, 0.1-0.5 parts of nonionic wetting agent, 0.05-0.20 parts of defoamer, and 80-130 parts of deionized water; The resulting interfacial ceramic microparticles have boehmite particles as the core, and the outer surface of the core is provided with an epoxy silane anchoring layer fixed by Al-O-Si bonds and Si-O-Si bonds. An organic transition layer containing secondary amine linkage sites and tertiary amine end groups is connected to the outside of the epoxy silane anchoring layer by ring opening of 3-dimethylaminopropylamine. The secondary amine linkage sites and polyethylene glycol diglycidyl ether form a thin-layer polyether bridging network. The tertiary amine end groups are converted into hydroxysulfobetaine groups containing quaternary ammonium cations, hydroxyl groups and sulfonate anions in the same side chain.

[0005] Furthermore, the interface ceramic microparticles are made from the following raw materials in parts by weight: 75-82 parts boehmite, 5-8 parts 3-glycidyl etheroxypropyltrimethoxysilane, 3-5 parts 3-dimethylaminopropylamine, 3-6 parts polyethylene glycol diglycidyl ether, and 6-10 parts sodium 3-chloro-2-hydroxypropanesulfonate.

[0006] Furthermore, the method for preparing the interfacial ceramic microparticles includes the following steps: S1. Add the boehmite to 5.0-6.5 times its mass of deionized water, stir at 40-50℃ and 900-1100 r / min for 20-40 min, add 10% acetic acid aqueous dispersion, adjust the pH to 4.2-4.8, and then ultrasonically disperse at 300-500W for 15-25 min to obtain activated boehmite dispersion.

[0007] S2. The 3-glycidyl etheroxypropyltrimethoxysilane is added to a mixture of 120-160 parts anhydrous ethanol and 25-35 parts deionized water, and a 10% (w / w) aqueous dispersion of acetic acid is added to adjust the pH to 4.2-4.8. The mixture is hydrolyzed at 25-35℃ and 500-700 r / min for 30-50 min. The resulting hydrolysate is added dropwise to the activated boehmite dispersion at a rate of 0.5-0.8 parts / min. After the addition is complete, the mixture is reacted at 55-65℃ and 600-800 r / min for 2-3 h to obtain an epoxysilane-grafted boehmite dispersion.

[0008] S3. Disperse the 3-dimethylaminopropylamine in 80-110 parts of deionized water, add it dropwise to the epoxysilane-grafted boehmite dispersion at a rate of 0.3-0.5 parts / min, add 10% sodium hydroxide aqueous dispersion, adjust the pH to 8.8-9.3, and react at 45-55℃ and 600-800 r / min for 2-3 h to obtain a tertiary amine interfacial boehmite dispersion.

[0009] S4. Disperse the polyethylene glycol diglycidyl ether in 100-140 parts of deionized water, and add it dropwise to the tertiary amine interfacial boehmite dispersion at a rate of 0.2-0.4 parts / min. Add 10% sodium hydroxide aqueous dispersion by mass, maintain the pH at 9.0-9.5, and react at 50-60℃ and 500-700 r / min for 3-4 hours to form a polyether bridging network and obtain a polyether bridging interfacial boehmite dispersion.

[0010] S5. Disperse the sodium 3-chloro-2-hydroxypropanesulfonate in 120-160 parts of deionized water, and add it dropwise to the polyether-bridged interface boehmite dispersion at a rate of 0.3-0.5 parts / min. Add 10% sodium hydroxide aqueous dispersion and maintain the pH at 8.2-8.8. React at 75-85℃ and 500-700 r / min for 6-8 h. After the reaction, centrifuge at 5000-7000×g for 8-12 min. Wash the obtained solid three times with deionized water and twice with anhydrous ethanol. Dry it at 60-70℃ and a vacuum degree of not less than 0.08 MPa for 10-14 h. After air jet pulverization and passing through a 1000-mesh sieve, obtain the interface ceramic microparticles.

[0011] The interfacial ceramic microparticles use boehmite as a core, and epoxy silane, after hydrolysis and condensation, is fixed to the particle surface through Al-O-Si and Si-O-Si bonds, allowing the organic groups to be independent of physical adsorption. After ring-opening, 3-dimethylaminopropylamine retains the secondary amine site and tertiary amine end group. The secondary amine reacts with polyethylene glycol diglycidyl ether to introduce a polyether bridging layer containing ether bonds and hydroxyl groups on the outer layer of the particles, reducing agglomeration caused by direct particle contact and improving the dispersion stability in the aqueous phase. The tertiary amine end group reacts with sodium 3-chloro-2-hydroxypropanesulfonate to form a hydroxysulfobetaine group containing quaternary ammonium cations, hydroxyl groups, and sulfonate anions in the same side chain. This group can enhance the affinity of the particle surface for the aqueous phase and carbonate electrolytes through ion hydration and hydrogen bonding. The polyether bridging layer is covalently fixed with the betaine side chain, which reduces the interfacial fluctuations caused by the release, migration and desorption of wetting components, keeps the particles dispersed during storage, shearing and coating, and allows the ceramic layer to retain the electrolyte to enter the required interparticle channels, which addresses the problems of easy particle flocculation, unstable wetting and insufficient local wetting in the prior art.

[0012] Furthermore, the inorganic heat-resistant filler is selected from at least one of α-alumina, γ-alumina, and unmodified boehmite.

[0013] Furthermore, the water-based adhesive is selected from at least one of water-based polyacrylate emulsion, styrene-butadiene latex, and polyvinyl alcohol.

[0014] Furthermore, the nonionic wetting agent is selected from at least one of fatty alcohol polyoxyethylene ether, polyoxypropylene polyoxyethylene copolymer, and polyether modified silicone oil.

[0015] Furthermore, the hydrolysate obtained in S2 is added dropwise within 30 minutes after the hydrolysis is completed.

[0016] Furthermore, in step S5, deionized water is used for washing until the conductivity of the final washing solution is no greater than 80 μS / cm, and the pH of the final washing solution is controlled to be 6.5-7.5; the inlet pressure of the air jet mill is 0.60-0.80 MPa, and the material temperature during the milling process is no higher than 40℃.

[0017] Furthermore, the dispersant is selected from at least one of ammonium polyacrylate, sodium polyacrylate, and sodium hexametaphosphate.

[0018] Furthermore, the thickener is selected from at least one of sodium carboxymethyl cellulose, hydroxyethyl cellulose, and xanthan gum.

[0019] Furthermore, the defoamer is polydimethylsiloxane.

[0020] A method for preparing a highly wettable modified ceramic slurry includes the following steps: B1. Take 35%-50% of the total mass of the deionized water, and add the dispersant and thickener sequentially under stirring conditions of 25-35℃ and 600-900r / min. Continue stirring for 20-40min to fully hydrate the thickener and obtain an aqueous premix.

[0021] B2. When the aqueous premixed liquid is in a high-shear dispersion state, the interfacial ceramic particles and inorganic heat-resistant filler are added sequentially. After the addition is completed, high-shear dispersion is continued, and then the resulting dispersion system is subjected to cyclic bead milling to obtain ceramic dispersion base material.

[0022] B3. Add the remaining deionized water to the ceramic dispersion base, and add the water-based binder, nonionic wetting agent and defoamer in sequence at 20-30℃ and 400-700r / min. After the addition is completed, continue stirring for 30-50min to obtain the initial ceramic slurry.

[0023] B4. Degas the initial ceramic slurry under a vacuum of 0.080-0.095 MPa for 15-30 minutes, and then filter it through a 200-300 mesh sieve to obtain the highly wettable modified ceramic slurry.

[0024] Furthermore, in B2, the high-shear dispersion rotation speed is 1800-2600 r / min, and the high-shear dispersion time is 25-45 min; the circulating bead milling process uses zirconia grinding beads with a particle size of 0.20-0.40 mm, the grinding bead filling rate is 60%-75%, the bead milling linear speed is 8-12 m / s, the process is repeated 2-4 times, and the material temperature is controlled not to exceed 35℃ during the bead milling process.

[0025] The application of a highly wettable modified ceramic slurry in the preparation of lithium-ion battery separators or sodium-ion battery separators is characterized by coating the highly wettable modified ceramic slurry onto at least one surface of a polyethylene microporous base membrane, a polypropylene microporous base membrane, or a polyethylene / polypropylene / polyethylene composite microporous base membrane using a microgravure coating method or a slot extrusion coating method, followed by segmented drying at 50-85°C to form a dry coating amount of 1.5-4.5 g / m² on the surface of the microporous base membrane. 2 A ceramic coating is applied to obtain a ceramic-coated separator for use in lithium-ion or sodium-ion batteries.

[0026] The highly wettable modified ceramic slurry of this invention uses interfacial ceramic microparticles and inorganic heat-resistant fillers as the ceramic phase. The polyether structure and hydroxysulfobetaine groups on the surface of the interfacial ceramic microparticles can improve the affinity of the particles for the aqueous phase and reduce agglomeration and sedimentation caused by direct contact between particles, thus maintaining a uniform distribution of the ceramic phase in the slurry. Dispersants are used to stabilize the particle suspension, thickeners adjust the slurry viscosity and storage stability, and aqueous binders fix the ceramic particles to the surface of the polyolefin microporous base film during drying, ensuring a continuous coating and maintaining interparticle porosity. Nonionic wetting agents improve the spreading of the slurry on low surface energy base films, and the hydrophilic and electrophilic groups fixed on the surface of the interfacial ceramic microparticles continue to exert interfacial wetting effects after film formation, reducing the impact of external wetting component migration on the coating state. Ceramic particles restrict the dimensional changes of polyolefin-based films when heated, and the interparticle channels in the coating facilitate the entry of electrolyte along the surface and thickness directions. Polyether chains, hydroxyl groups, quaternary ammonium groups, and sulfonate groups can interact with the electrolyte through dipole interactions, ionic interactions, and hydrogen bonding, allowing the electrolyte to spread in the coating. This balances coating uniformity, wettability, and ion transport conditions without excessively compressing the pores.

[0027] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention constructs a continuous covalent interface layer on the surface of boehmite, which reduces the tendency of ceramic particles to agglomerate and settle, and keeps the slurry stably dispersed during storage, shearing and coating.

[0028] 2. This invention utilizes a polyether bridging network and hydroxysulfobetaine side chains to enhance the affinity of particles for the aqueous phase and electrolyte, thereby improving slurry spreading, coating wetting, and liquid absorption properties.

[0029] 3. This invention enables the interfacial ceramic microparticles and inorganic heat-resistant fillers to form a uniformly distributed ceramic coating, while retaining interparticle channels, so that the diaphragm can take into account both air permeability and thermal dimensional stability. Attached Figure Description

[0030] Figure 1 The infrared spectrum of the interfacial ceramic microparticles prepared in Example 1 of this invention is shown. Detailed Implementation

[0031] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Preparation Example 1 Preparation of interfacial ceramic microparticles: 1. Raw material composition By weight, the following raw materials are included: boehmite: 78.0 parts; 3-glycidyl etheroxypropyltrimethoxysilane: 6.5 parts; 3-dimethylaminopropylamine: 4.0 parts; polyethylene glycol diglycidyl ether: 4.5 parts; sodium 3-chloro-2-hydroxypropanesulfonate: 8.0 parts.

[0033] The boehmite was purchased from Shandong Guoci Functional Materials Co., Ltd., model: HBO-070.

[0034] The polyethylene glycol diglycidyl ether was purchased from Sigma-Aldrich, item number 475696.

[0035] 2. Preparation method: S1. Weigh 468.0 parts of deionized water and add it to the reaction vessel. Raise the water temperature to 45℃ and slowly add the boehmite at 1000 r / min. The solid-liquid mass ratio of boehmite to deionized water is 1:6.0, and the addition time is controlled at 15 min. After the addition is completed, continue stirring at 45℃ and 1000 r / min for 30 min. Then add 10% (w / w) acetic acid aqueous dispersion to adjust the pH of the dispersion to 4.5. Maintain the dispersion temperature at 45℃ and ultrasonically disperse it at 400W power for 20 min in an air atmosphere. During the ultrasonication process, use circulating cooling water to control the material temperature to not exceed 48℃, thus obtaining an activated boehmite dispersion.

[0036] S2. Add 140.0 parts of anhydrous ethanol and 30.0 parts of deionized water to another reaction vessel, and stir and mix at 30°C and 600 r / min for 10 min. Then add the 3-glycidyl etheroxypropyltrimethoxysilane and a 10% (w / w) aqueous dispersion of acetic acid, adjust the pH of the mixture to 4.5, and hydrolyze in air at 30°C and 600 r / min for 40 min to obtain an epoxysilane hydrolysate. Within 10 min after hydrolysis, begin dropwise addition. Heat the activated boehmite dispersion to 60°C and maintain stirring at 700 r / min, adding the epoxysilane hydrolysate dropwise at a rate of 0.80 parts / min for approximately 221 min. After the dropwise addition is complete, install a reflux condenser and continue the reaction at 60°C and 700 r / min for 2.5 h to obtain an epoxysilane-grafted boehmite dispersion.

[0037] S3. Add the 3-dimethylaminopropylamine to 95.0 parts of deionized water and stir at 25°C and 500 r / min for 15 min to obtain a 3-dimethylaminopropylamine aqueous dispersion. Purge the epoxysilane-grafted boehmite dispersion with nitrogen gas at 100 mL / min for 15 min, then adjust the nitrogen flow rate to 20 mL / min to maintain a slight positive pressure, and adjust the dispersion temperature to 50°C and the stirring speed to 700 r / min. Add the 3-dimethylaminopropylamine aqueous dispersion dropwise at a rate of 0.50 parts / min for 198 min. After the dropwise addition is completed, add a 10% (w / w) sodium hydroxide aqueous dispersion to adjust the pH of the system to 9.0. Continue the reaction under nitrogen protection at 50°C and 700 r / min for 2.5 h to obtain a tertiary amine interfacial boehmite dispersion.

[0038] S4. Add the polyethylene glycol diglycidyl ether to 120.0 parts of deionized water and stir at 30℃ and 500 r / min for 20 min to obtain a polyethylene glycol diglycidyl ether aqueous dispersion. Adjust the temperature of the tertiary amine interfacial boehmite dispersion to 55℃ and the stirring speed to 600 r / min, while maintaining a nitrogen flow rate of 20 mL / min; add the polyethylene glycol diglycidyl ether aqueous dispersion dropwise at a rate of 0.40 parts / min. After the dropwise addition is complete, add a 10% (w / w) sodium hydroxide aqueous dispersion to adjust the pH of the system to 9.2, and continue the reaction at 55℃ and 600 r / min for 3.5 h to obtain a polyether-bridged interfacial boehmite dispersion.

[0039] S5. Add the sodium 3-chloro-2-hydroxypropanesulfonate to 140.0 parts of deionized water and stir at 35°C and 500 r / min for 20 min to obtain an aqueous dispersion of sodium 3-chloro-2-hydroxypropanesulfonate. Heat the polyether-bridged boehmite dispersion to 80°C and maintain stirring at 600 r / min. Under nitrogen protection at 20 mL / min, add the sodium 3-chloro-2-hydroxypropanesulfonate aqueous dispersion dropwise at a rate of 0.50 parts / min for 296 min. After the addition is complete, add a 10% (w / w) sodium hydroxide aqueous dispersion to adjust the pH of the system to 8.5. Continue the reaction at 80°C and 600 r / min for 7 h. After the reaction is complete, cool the resulting dispersion to 30°C and centrifuge at a relative centrifugal force of 6000 × g for 10 min, discarding the supernatant. Add 300.0 parts of deionized water to the obtained solid, redisperse at 25℃ and 800 r / min for 10 min, then centrifuge at 6000×g for 10 min. Repeat the above deionized water washing operation 3 times to ensure that the conductivity of the final washing solution is no greater than 80 μS / cm and the pH is 6.5-7.5. Then add 200.0 parts of anhydrous ethanol to the washed solid, disperse at 25℃ and 600 r / min for 8 min, then centrifuge at 6000×g for 10 min. Repeat the anhydrous ethanol washing operation 2 times. Place the ethanol-washed solid under vacuum drying conditions and dry at 65℃ and a vacuum degree of 0.085 MPa for 12 h. The dried material is then subjected to air jet milling with an inlet pressure of 0.70 MPa. During the milling process, the material temperature is controlled below 40℃ by cooling airflow. Finally, it is passed through a 1000-mesh sieve to obtain interfacial ceramic microparticles.

[0040] like Figure 1 As shown in the figure, approximately 3430cm -1 The broad absorption band at approximately 1650-1680 cm⁻¹ can be attributed to the hydroxyl groups on the boehmite surface, the hydroxyl groups generated after the epoxy ring-opening process, and the stretching vibrations of OH groups in adsorbed water. -1 The area primarily corresponds to the bending vibrations of adsorbed water; approximately 2950 cm. -1 The shoulder peaks correspond to aliphatic CH stretching vibrations in the propyl, dimethylaminopropyl, and polyethylene glycol segments, indicating that organic segments have been introduced into the particle surface. (Approximately 1470 cm⁻¹) -1 The absorption at this point can be achieved through the -CH2- bending vibration and the quaternization of CN. + Related vibrations contribute to this. 1200-1000cm -1 A strong and broad composite absorption band appears in the region, with approximately 1105 cm⁻¹ as the largest. -1 The main peak can be formed by the superposition of Si-O-Al or Si-O-Si, polyether COC, and sulfonate S=O vibrations, which is consistent with silane grafting, polyether bridging, and the introduction of sulfonate groups. The sulfobetaine structure is usually located at about 1210-1180 cm⁻¹.-1 and 1040cm -1 There is relevant absorption nearby. Approximately 775 -1 630 -1 and 490cm -1 The presence of boehmite Al-O and Al-OH framework vibrations indicates that the inorganic nucleus was not significantly destroyed; no protruding 910 cm² core is visible in the image. -1 The independent absorption of epoxy groups, combined with the aforementioned characteristics of newly added organic segments, ether bonds, and sulfonates, indicates that the epoxy silane grafting, amine ring-opening, polyether bridging, and quaternization reactions have been achieved.

[0041] Comparative Preparation Example 1 The preparation of the interfacial ceramic microparticles was carried out by referring to the preparation method in Preparation Example 1, except that the boehmite was replaced by α-alumina, and everything else remained the same as in Preparation Example 1.

[0042] The α-alumina was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., item number: A664978.

[0043] Comparative Preparation Example 2 The preparation of the interfacial ceramic microparticles was carried out in accordance with the preparation method in Preparation Example 1, except that 3-glycidyl etheroxypropyltrimethoxysilane was replaced by 3-aminopropyltrimethoxysilane in equal mass, while the rest remained the same as in Preparation Example 1.

[0044] Comparative preparation example 3 The preparation of the interfacial ceramic microparticles was carried out by referring to the preparation method in Preparation Example 1, except that 3-dimethylaminopropylamine was replaced with ethylenediamine by mass, and the rest remained the same as in Preparation Example 1.

[0045] Comparative preparation example 4 The preparation of the interfacial ceramic microparticles was carried out in accordance with the preparation method in Preparation Example 1, except that the polyethylene glycol diglycidyl ether was replaced by 1,4-butanediol diglycidyl ether, and the rest remained the same as in Preparation Example 1.

[0046] Comparative preparation example 5 The preparation of the interfacial ceramic microparticles was carried out by referring to the preparation method in Preparation Example 1, except that sodium 3-chloro-2-hydroxypropanesulfonate was replaced by sodium chloroacetate in equal mass, and the rest remained the same as in Preparation Example 1.

[0047] Example 1 Preparation of a highly wettable modified ceramic slurry: 1. Raw material composition: By weight, it includes the following raw materials: Interfacial ceramic microparticles: 32.0 parts of the interfacial ceramic microparticles obtained in Preparation Example 1.

[0048] Inorganic heat-resistant filler: selected from unmodified boehmite, 14.0 parts.

[0049] Water-based adhesive: 4.0 parts of water-based polyacrylate emulsion.

[0050] Dispersant: Ammonium polyacrylate, 0.50 parts.

[0051] Thickener: Sodium carboxymethyl cellulose, 0.60 parts.

[0052] Nonionic wetting agent: 0.30 parts of polyoxypropylene-polyoxyethylene copolymer.

[0053] Defoamer: 0.10 parts of polydimethylsiloxane.

[0054] Deionized water: 105.0 parts.

[0055] The boehmite was purchased from Shandong Guoci Functional Materials Co., Ltd., model: HBO-070.

[0056] The aqueous polyacrylate emulsion was purchased from Shanghai Sanrui Polymer Materials Co., Ltd., with the grade LIB-S101.

[0057] The ammonium polyacrylate was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number: P304873.

[0058] The polyoxypropylene-polyoxyethylene copolymer was purchased from Shanghai McLean Biochemical Technology Co., Ltd., item number: T832531.

[0059] The polydimethylsiloxane was purchased from Shanghai McLean Biochemical Technology Co., Ltd., item number: P708881.

[0060] 2. Preparation method: B1. Weigh 42.0 parts of deionized water and add it to a pulping container, the amount of deionized water used accounting for 40.0% of the total mass of deionized water. Under an air atmosphere, adjust the temperature of the deionized water to 30℃ and stir at 750 r / min for 5 min. Maintaining the temperature at 30℃ and the stirring speed at 750 r / min, add the ammonium polyacrylate at a rate of 0.167 parts / min; after the addition is complete, continue stirring for 5 min. Then, uniformly add the sodium carboxymethyl cellulose at a rate of 0.10 parts / min. After the sodium carboxymethyl cellulose is completely added, continue stirring at 30℃ and 750 r / min for 40 min to obtain an aqueous premix.

[0061] B2. Maintain the temperature of the aqueous premix at 30°C, switch the stirring mode to high-shear dispersion, and adjust the stirring speed to 2200 r / min. Add the interfacial ceramic particles at a rate of 2.67 parts / min; after the interfacial ceramic particles are added, add the unmodified boehmite at a rate of 2.00 parts / min. Calculate the high-shear dispersion time from the start of adding the interfacial ceramic particles. After the unmodified boehmite is added, continue high-shear dispersion at 2200 r / min for 16 min, making the total high-shear dispersion time 35 min. During the high-shear dispersion process, use circulating cooling water to control the temperature, keeping the material temperature between 30-34°C and not exceeding 35°C. Perform a circulating bead milling treatment using 0.30 mm zirconia grinding beads with a bead filling rate of 70% and a bead milling linear velocity of 10 m / s. One cycle is considered as one pass of all material through the bead mill chamber, and the process is repeated 3 times, with each cycle lasting 15 min, for a total bead milling time of 45 min. During the bead milling process, circulating cooling water is continuously introduced to ensure that the material temperature does not exceed 35℃. After bead milling, the material is stirred at 500 r / min for 10 min to obtain a ceramic dispersion matrix.

[0062] B3. Cool the ceramic dispersion base to 25°C and adjust the stirring speed to 550 r / min. Add the remaining 63.0 parts of deionized water at a rate of 6.30 parts / min; continue stirring for 5 min after the water addition is complete. Maintaining the material temperature at 25°C and the stirring speed at 550 r / min, add the aqueous polyacrylate emulsion at a rate of 0.267 parts / min; continue stirring for 5 min after the addition is complete. Then add the polyoxypropylene-polyoxyethylene copolymer at a rate of 0.10 parts / min and continue stirring for 5 min; then add the polydimethylsiloxane dropwise at a rate of 0.020 parts / min. After all raw materials have been added, continue stirring at 25°C and 550 r / min in an air atmosphere for 40 min to obtain the initial ceramic slurry.

[0063] B4. Maintain the initial temperature of the ceramic slurry at 25°C, and gradually evacuate the vacuum while stirring at a low speed of 100 r / min, achieving a vacuum degree of 0.090 MPa within 5 minutes. After reaching the set vacuum degree, stop stirring and continue to allow the slurry to stand for degassing for 15 minutes under a vacuum degree of 0.090 MPa, for a total vacuum degassing time of 20 minutes. After degassing, slowly restore the pressure to normal, and filter the slurry through a 250-mesh stainless steel screen, maintaining the slurry temperature at 25°C during filtration. Collect the filtrate to obtain a highly wettable modified ceramic slurry.

[0064] Example 2 The preparation of a highly wettable modified ceramic slurry is carried out according to the preparation method in Example 1, with the following overall adjustments: 38.0 parts of interfacial ceramic microparticles, 18.0 parts of unmodified boehmite, 5.0 parts of aqueous polyacrylate emulsion, 0.80 parts of ammonium polyacrylate, 1.00 parts of sodium carboxymethyl cellulose, 0.50 parts of polyoxypropylene-polyoxyethylene copolymer, 0.20 parts of polydimethylsiloxane, and 130.0 parts of deionized water. The other components remain the same as in Example 1.

[0065] Example 3 The preparation of a highly wettable modified ceramic slurry is carried out by referring to the preparation method in Example 1, except that the total amount of each raw material is adjusted as follows: 25.0 parts of interfacial ceramic microparticles, 10.0 parts of unmodified boehmite, 2.0 parts of aqueous polyacrylate emulsion, 0.20 parts of ammonium polyacrylate, 0.30 parts of sodium carboxymethyl cellulose, 0.10 parts of polyoxypropylene-polyoxyethylene copolymer, 0.05 parts of polydimethylsiloxane, and 80.0 parts of deionized water. The other components are the same as in Example 1.

[0066] Example 4 The preparation of a highly wettable modified ceramic slurry is carried out by referring to the preparation method in Example 1, except that the unmodified boehmite and other materials are replaced with α-alumina, and the rest is the same as in Example 1.

[0067] The α-alumina was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., item number: A664978.

[0068] Example 5 The preparation of a highly wettable modified ceramic slurry is carried out by referring to the preparation method in Example 1, except that the water-based polyacrylate emulsion is replaced by styrene-butadiene latex in equal mass, and the rest is the same as in Example 1.

[0069] The styrene-butadiene latex was purchased from Zhejiang Tianchen Rubber Industry Co., Ltd.

[0070] Example 6 The preparation of a highly wettable modified ceramic slurry is carried out by referring to the preparation method in Example 1, except that the polyoxypropylene polyoxyethylene copolymer is replaced by fatty alcohol polyoxyethylene ether in equal mass, and the rest is the same as in Example 1.

[0071] The fatty alcohol polyoxyethylene ether was purchased from Shanghai McLean Biochemical Technology Co., Ltd., item number: A909307.

[0072] Comparative Examples 1-5 The preparation of a highly wettable modified ceramic slurry, referring to the preparation method in Example 1, involves sequentially replacing the interfacial ceramic particles with the interfacial ceramic particles in Comparative Preparation Examples 1-5.

[0073] Comparative Example 6 The preparation of a highly wettable modified ceramic slurry is the same as in Example 1, except that the interfacial ceramic particles are not added.

[0074] Comparative Example 7 The preparation of a highly wettable modified ceramic slurry is carried out by referring to the preparation method of Example 1, except that the interfacial ceramic particles are replaced by spherical silica in equal mass, and the rest is the same as in Example 1.

[0075] The silica used in the ball was purchased from Shanghai McLean Biochemical Technology Co., Ltd., item number: S675805.

[0076] Comparative Example 8 The preparation of a highly wettable modified ceramic slurry is carried out by referring to the preparation method of Example 1, except that 32.0 parts by mass of interfacial ceramic microparticles are replaced with 32.0 parts of unmodified boehmite, and the rest is the same as in Example 1.

[0077] The unmodified boehmite was purchased from Shandong Guoci Functional Materials Co., Ltd., and its model number is HBO-070.

[0078] Comparative Example 9 The preparation of a highly wettable modified ceramic slurry is carried out by referring to the preparation method of Example 1, except that the polyoxypropylene-polyoxyethylene copolymer is replaced by sodium dodecyl sulfate in equal mass, and the rest is the same as in Example 1.

[0079] Application of a highly wettable modified ceramic slurry in the preparation of lithium-ion battery separators or sodium-ion battery separators: The highly wettable modified ceramic slurry of this invention is used to prepare ceramic-coated separators for lithium-ion or sodium-ion batteries. The ceramic slurry is the highly wettable modified ceramic slurry prepared in Example 1. Before use, the highly wettable modified ceramic slurry is stirred for 10-20 minutes at 20-30°C and 300-500 r / min to restore the slurry to a uniform flow state, ensuring that no obvious bubbles are generated during stirring. A polyethylene microporous membrane, a polypropylene microporous membrane, or a polyethylene / polypropylene / polyethylene composite microporous membrane is continuously unwound, keeping the membrane surface clean, flat, and free of obvious wrinkles.

[0080] The highly wettable modified ceramic slurry is uniformly coated onto one or both surfaces of a microporous substrate membrane using either a microgravure coating method or a slot extrusion coating method. During the coating process, the slurry is continuously supplied, ensuring a uniform distribution of the wet coating along the width of the substrate membrane, preventing continuous edge shrinkage, exposed substrate, or localized accumulation. The coated substrate membrane is then sequentially dried in segmented drying zones at 55°C, 70°C, and 80°C for 1.5 min, 2.0 min, and 2.0 min, respectively, allowing for gradual evaporation of moisture and enabling the water-based binder to fix the interfacial ceramic particles and inorganic heat-resistant fillers to the surface of the microporous substrate membrane.

[0081] The dry coating weight of the resulting ceramic coating is 3.0 g / m². When double-sided coating is used, the dry coating weight is the total dry coating weight of both surfaces. After drying, the ceramic-coated separator is cooled, drawn, and wound to obtain a ceramic-coated separator for lithium-ion or sodium-ion batteries.

[0082] The resulting ceramic-coated separator can be cut according to the battery design dimensions and wound or stacked with the positive and negative electrode sheets to form a battery cell. During assembly, the ceramic coating is positioned on the positive electrode side, the negative electrode side, or, under double-sided coating conditions, facing the positive and negative electrode sheets respectively. After the battery cell is injected with lithium-ion battery electrolyte or sodium-ion battery electrolyte, the interparticle pores in the ceramic coating are used to form electrolyte wetting and ion transport channels. The polyether structure, hydroxyl groups, and hydroxysulfobetaine groups on the surface of the interfacial ceramic particles are used to improve the affinity of the ceramic coating for the electrolyte, and the ceramic phase is used to limit the dimensional changes of the polyolefin microporous membrane when heated.

[0083] Performance testing: The ceramic slurries prepared in Examples 1-6 and Comparative Examples 1-9 were stirred at 25°C and 400 r / min for 15 min, respectively. They were then coated on one side of a 12.0 ± 0.3 μm thick polyethylene microporous membrane using a microgravure coating method, with the dry coating amount controlled at 3.0 g / m². 2 The coated base film was dried sequentially at 55℃, 70℃, and 80℃ for 1.5 min, 2.0 min, and 2.0 min, respectively, and then cooled and wound up. The diaphragm samples were conditioned for at least 4 hours at 23±2℃ and 50±10% relative humidity, according to the standard environment specified in GB / T2918-2018. The coating amount and segmented drying conditions described above are consistent with the diaphragm application conditions in the manuscript.

[0084] 1. Slurry storage stability and coating defect test: The initial viscosity η0 was measured at 25±1℃ using a rotational viscometer with rotor No. 3 and a speed of 60 r / min. 200 mL of slurry was placed in a 250 mL graduated cylinder, sealed, and allowed to stand for 7 days. The height of the supernatant layer h and the total height of the liquid column H were recorded. The separation rate was calculated as h / H×100%. After re-stirring at 400 r / min for 10 min, η7 was measured. The viscosity change rate was calculated as |η7-η0| / η0×100%. Five 100 mm × 100 mm areas were randomly selected from the obtained diaphragm for backlight imaging. The percentage of the projected area of ​​edge shrinkage, exposed substrate, pinholes, and particle accumulation to the tested area was calculated as the coating defect area rate. The data are shown in Table 1.

[0085] 2. Electrolyte Wetting Performance Test: In an argon-filled glove box with moisture and oxygen content not exceeding 1 ppm, a 1.0 mol / L LiPF6 EC / EMC / DMC mixed dispersion was used as the test electrolyte, with a volume ratio of 1:1:1 for the three solvents. 3.0 μL of electrolyte was added to the ceramic coating surface, and the contact angle at 1 second of droplet contact was recorded. A separate 50 mm × 50 mm sample was vacuum dried at 60℃ for 4 h, weighed (m0), immersed in the electrolyte for 30 min, removed, and vertically drained for 30 s, with only the edge liquid removed. The sample was then weighed (m1), and the liquid absorption rate was calculated as (m1 - m0) / m0 × 100%. The data are shown in Table 1.

[0086] 3. Air permeability test: The test shall be conducted in accordance with GB / T36363-2018. The sample shall be held flat in a container with an effective area of ​​6.45 cm². 2 The time required for 100 mL of air to pass through the sample was recorded in the test head under a pressure difference of 1.21 kPa. The data are shown in Table 2.

[0087] 4. Heat shrinkage rate test: The test was conducted according to GB / T36363-2018. A 100mm × 100mm sample was cut, and initial gauge lengths L0 were marked on both the longitudinal and transverse sides. The sample was placed in a tension-free oven at 105±2℃ for 1 hour, then removed and cooled in a standard environment for 30 minutes. The corresponding gauge length L1 was then measured. The longitudinal or transverse heat shrinkage rate = (L0-L1) / L0×100%. The data are shown in Table 2.

[0088] Table 1. Slurry storage, coating and electrolyte wetting properties

[0089] Table 2. Air permeability and thermal dimensional stability of ceramic-coated diaphragms

[0090] The test results show that Example 1 exhibits a balanced trend in slurry storage, base film spreading, electrolyte wetting, pore retention, and thermal dimensional control. The silane anchoring layer on the surface of the interfacial ceramic particles maintains the connection between the outer organic structure and the boehmite core. The polyether bridging network introduces ether bonds and hydroxyl groups, forming spatial intervals between particles. The hydroxysulfobetaine side chain contains quaternary ammonium groups, hydroxyl groups, and sulfonate groups, which can improve the affinity of the particles for the aqueous phase and carbonate electrolyte. The ceramic particles maintain a uniform distribution after storage and re-stirring, with less edge shrinkage, exposed substrate, and particle accumulation during coating, and retains continuous interparticle channels after drying. In Example 2, the increased amounts of thickener, binder, and ceramic phase enhance slurry suspension and thermal constraint, while also increasing air permeability resistance. In Example 3, the system viscosity and binder phase content are lower, the pores are more open, and the coating integrity and thermal constraint are slightly reduced. After replacing inorganic fillers, binders, or nonionic wetting agents within the scope of the claims, the overall trend is similar, indicating that the technical effect does not depend on any particular conventional additive. Comparative Examples 1 to 5, by changing the surface reaction basis of the core material, epoxy anchoring points, tertiary amine end groups, polyether segments, and sulfobetaine structure, respectively, resulted in a decrease in interfacial layer continuity, hydration capacity, or steric stabilization. Comparative Example 6 lacked interfacial ceramic microparticles, and the low solids content resulted in poor apparent delamination, but the coating integrity, wetting, and thermal stability tended to decrease. Comparative Examples 7 and 8 only retained the filling effect of ordinary inorganic particles, making it difficult to maintain a consistent interfacial state from storage to film formation. In Comparative Example 9, the use of anionic surfactant altered the particle distribution and pore state due to changes in free components, foam, and drying migration. While the ceramic phase can limit the thermal dimensional changes of polyolefin-based films, wetting, permeability, and thermal stability can only be maintained simultaneously when the interfacial structure, slurry rheology, and film porosity are in a matched state.

[0091] 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 highly wettable modified ceramic slurry, characterized in that, It is composed of the following components in parts by weight: 25-38 parts of interfacial ceramic microparticles, 10-18 parts of inorganic heat-resistant filler, 2-5 parts of water-based binder, 0.2-0.8 parts of dispersant, 0.3-1.0 parts of thickener, 0.1-0.5 parts of nonionic wetting agent, 0.05-0.20 parts of defoamer, and 80-130 parts of deionized water; The resulting interfacial ceramic microparticles have boehmite particles as the core, and the outer surface of the core is provided with an epoxy silane anchoring layer fixed by Al-O-Si bonds and Si-O-Si bonds. An organic transition layer containing secondary amine linkage sites and tertiary amine end groups is connected to the outside of the epoxy silane anchoring layer by ring opening of 3-dimethylaminopropylamine. The secondary amine linkage sites and polyethylene glycol diglycidyl ether form a thin-layer polyether bridging network. The tertiary amine end groups are converted into hydroxysulfobetaine groups containing quaternary ammonium cations, hydroxyl groups and sulfonate anions in the same side chain.

2. The highly wettable modified ceramic slurry according to claim 1, characterized in that, The interface ceramic microparticles are made from the following raw materials in parts by weight: 75-82 parts boehmite, 5-8 parts 3-glycidyl etheroxypropyltrimethoxysilane, 3-5 parts 3-dimethylaminopropylamine, 3-6 parts polyethylene glycol diglycidyl ether, and 6-10 parts sodium 3-chloro-2-hydroxypropanesulfonate.

3. The highly wettable modified ceramic slurry according to claim 2, characterized in that, The method for preparing the interface ceramic microparticles includes the following steps: S1. Add the boehmite to 5.0-6.5 times its mass of deionized water, stir at 40-50℃ and 900-1100 r / min for 20-40 min, add 10% acetic acid aqueous dispersion, adjust the pH to 4.2-4.8, and then ultrasonically disperse at 300-500W for 15-25 min to obtain activated boehmite dispersion. S2. The 3-glycidyl etheroxypropyltrimethoxysilane is added to a mixture of 120-160 parts anhydrous ethanol and 25-35 parts deionized water, and a 10% (w / w) aqueous dispersion of acetic acid is added to adjust the pH to 4.2-4.

8. The mixture is hydrolyzed at 25-35℃ and 500-700 r / min for 30-50 min. The resulting hydrolysate is added dropwise to the activated boehmite dispersion at a rate of 0.5-0.8 parts / min. After the addition is complete, the mixture is reacted at 55-65℃ and 600-800 r / min for 2-3 h to obtain an epoxysilane-grafted boehmite dispersion. S3. Disperse the 3-dimethylaminopropylamine in 80-110 parts of deionized water, add it dropwise to the epoxysilane-grafted boehmite dispersion at a rate of 0.3-0.5 parts / min, add 10% sodium hydroxide aqueous dispersion, adjust the pH to 8.8-9.3, and react at 45-55℃ and 600-800 r / min for 2-3 h to obtain a tertiary amine interfacial boehmite dispersion; S4. Disperse the polyethylene glycol diglycidyl ether in 100-140 parts of deionized water, add it dropwise to the tertiary amine interfacial boehmite dispersion at a rate of 0.2-0.4 parts / min, add 10% sodium hydroxide aqueous dispersion, maintain the pH at 9.0-9.5, and react at 50-60℃ and 500-700 r / min for 3-4 h to form a polyether bridging network and obtain a polyether bridging interfacial boehmite dispersion; S5. Disperse the sodium 3-chloro-2-hydroxypropanesulfonate in 120-160 parts of deionized water, and add it dropwise to the polyether-bridged interface boehmite dispersion at a rate of 0.3-0.5 parts / min. Add 10% sodium hydroxide aqueous dispersion and maintain the pH at 8.2-8.

8. React at 75-85℃ and 500-700 r / min for 6-8 h. After the reaction, centrifuge at 5000-7000×g for 8-12 min. Wash the obtained solid three times with deionized water and twice with anhydrous ethanol. Dry it at 60-70℃ and a vacuum degree of not less than 0.08 MPa for 10-14 h. After air jet pulverization and passing through a 1000-mesh sieve, obtain the interface ceramic microparticles.

4. The highly wettable modified ceramic slurry according to claim 1, characterized in that, The inorganic heat-resistant filler is selected from at least one of α-alumina, γ-alumina and unmodified boehmite.

5. The highly wettable modified ceramic slurry according to claim 1, characterized in that, The water-based adhesive is selected from at least one of water-based polyacrylate emulsion, styrene-butadiene latex, and polyvinyl alcohol; The nonionic wetting agent is selected from at least one of fatty alcohol polyoxyethylene ether, polyoxypropylene polyoxyethylene copolymer, and polyether modified silicone oil.

6. The highly wettable modified ceramic slurry according to claim 3, characterized in that, The hydrolysate obtained in S2 is added dropwise starting within 30 minutes after the hydrolysis is completed. In step S5, deionized water is used for washing until the conductivity of the final washing solution is no greater than 80 μS / cm, and the pH of the final washing solution is controlled to be 6.5-7.5; the inlet pressure of the air jet mill is 0.60-0.80 MPa, and the material temperature during the milling process is no higher than 40℃.

7. The highly wettable modified ceramic slurry according to claim 1, characterized in that, The dispersant is selected from at least one of ammonium polyacrylate, sodium polyacrylate and sodium hexametaphosphate; The thickener is selected from at least one of sodium carboxymethyl cellulose, hydroxyethyl cellulose, and xanthan gum; The defoamer is polydimethylsiloxane.

8. A method for preparing a highly wettable modified ceramic slurry as described in any one of claims 1-7, characterized in that, Includes the following steps: B1. Take 35%-50% of the total mass of the deionized water, add the dispersant and thickener sequentially under stirring conditions of 25-35℃ and 600-900r / min, and continue stirring for 20-40min to fully hydrate the thickener and obtain an aqueous premix. B2. When the aqueous premixed liquid is in a high-shear dispersion state, the interfacial ceramic particles and inorganic heat-resistant filler are added sequentially. After the addition is completed, high-shear dispersion is continued, and the resulting dispersion system is then subjected to a circulating bead milling process to obtain a ceramic dispersion base material. B3. Add the remaining deionized water to the ceramic dispersion base, and add the water-based binder, nonionic wetting agent and defoamer in sequence at 20-30℃ and 400-700r / min. After the addition is completed, continue stirring for 30-50min to obtain the initial ceramic slurry. B4. Degas the initial ceramic slurry under a vacuum of 0.080-0.095 MPa for 15-30 minutes, and then filter it through a 200-300 mesh sieve to obtain the highly wettable modified ceramic slurry.

9. The method for preparing the highly wettable modified ceramic slurry according to claim 8, characterized in that, The high-shear dispersion speed in B2 is 1800-2600 r / min, and the high-shear dispersion time is 25-45 min; the circulating bead milling process uses zirconia grinding beads with a particle size of 0.20-0.40 mm, the grinding bead filling rate is 60%-75%, the bead milling linear speed is 8-12 m / s, the process is repeated 2-4 times, and the material temperature is controlled not to exceed 35℃ during the bead milling process.

10. The application of a highly wettable modified ceramic slurry as described in any one of claims 1-7 in the preparation of lithium-ion battery separators or sodium-ion battery separators, characterized in that, The highly wettable modified ceramic slurry is coated onto at least one surface of a polyethylene microporous membrane, a polypropylene microporous membrane, or a polyethylene / polypropylene / polyethylene composite microporous membrane using a microgravure coating method or a slot extrusion coating method. After segmental drying at 50-85°C, a dry coating amount of 1.5-4.5 g / m² is formed on the surface of the microporous membrane. 2 The ceramic coating is applied to obtain a ceramic-coated separator for lithium-ion batteries or sodium-ion batteries; when coating one side, the dry coating amount is the dry coating amount of the ceramic coating on one side, and when coating two sides, the dry coating amount is the total dry coating amount of the two surfaces.

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