Waterborne ceramic slurry for coating, preparation method thereof and battery diaphragm
By combining modified mesoporous silica with fluorinated polybenzimidazole-silane coupling agent, a water-based ceramic slurry was prepared and polymer molecular brushes were grafted onto the surface of the polyolefin diaphragm substrate, which solved the problems of insufficient high temperature resistance and heat shrinkage resistance of the ceramic coated diaphragm and improved the safety and performance of lithium-ion batteries.
Patent Information
- Application Number
- CN202510809774.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-17
- Publication Date
- 2025-10-10
AI Technical Summary
The high temperature resistance and heat shrinkage resistance of existing ceramic coated diaphragms cannot meet the requirements under certain temperature conditions and need to be further improved.
Modified mesoporous silica is used as a binder, and the mesoporous silica is modified by a fluorinated polybenzimidazole-silane coupling agent to prepare a water-based ceramic slurry. Polymer molecular brushes are grafted on the surface of the polyolefin diaphragm substrate to improve the bonding force between the substrate and the ceramic particles and enhance the heat resistance of the diaphragm.
The heat resistance and high temperature resistance of lithium-ion battery separators are improved, the risk of thermal shrinkage of batteries is reduced, and safety is enhanced.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of lithium battery separator preparation, and in particular to a coating aqueous ceramic slurry, a preparation method thereof, and a battery separator. Background Art
[0002] With the worsening energy crisis and rising environmental awareness, the depletion of fossil fuels has drawn attention to new energy sources. Among the numerous new energy sources, lithium-ion batteries, thanks to their high energy density, excellent charge-discharge cycle performance, and mature industrial technology, have become the leading choice for mobile energy. Lithium-ion batteries primarily consist of four modules: a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is a key internal component in lithium-ion batteries. Key battery properties such as capacity, cycle performance, charge-discharge current density, high-temperature resistance, high strength, and safety are all directly related to the separator.
[0003] The most commonly used lithium-ion battery separators on the market are polyolefin separators, or coated separators based on polyolefin separators. Polyolefins are non-polar materials, with a significant difference in polarity from the polar electrolyte molecules. This results in insufficient affinity between the polyolefin separator and the electrolyte, making it difficult to retain large amounts of electrolyte for long periods of time, significantly impacting battery performance. Furthermore, due to the poor thermal stability of polyolefin materials, the separator in the battery shrinks when heated, causing a short circuit between the positive and negative electrodes, which can easily cause the battery to explode and pose safety concerns. Ceramic coating processes can address the poor thermal stability of polyolefin separators, but the high temperature resistance and heat shrinkage resistance of ceramic coated separators currently do not meet requirements under certain temperature conditions, and the high temperature resistance of ceramic coated separators needs to be further improved. Summary of the Invention
[0004] The present invention provides a water-based ceramic slurry for coating, a preparation method thereof, and a battery separator, which can solve the problem in the prior art that the high temperature resistance and heat shrinkage rate of the ceramic coated separator cannot meet the requirements under certain temperature conditions, and the high temperature resistance performance of the ceramic coated separator needs to be further improved.
[0005] The purpose of the present invention can be achieved through the following technical solutions:
[0006] In a first aspect, the present invention provides a water-based ceramic slurry for coating, comprising the following raw materials in parts by weight:
[0007] 10-12 parts of isooctyl acrylate;
[0008] 3-5 parts of methyl methacrylate;
[0009] 0.2-0.4 parts of acrylonitrile;
[0010] 5 parts of 2-ethylhexyl acrylate;
[0011] 0.1-0.3 parts of acrylamide;
[0012] 8-12 parts of modified mesoporous silica;
[0013] 1-1.5 parts emulsifier;
[0014] 70-80 parts deionized water;
[0015] 1-2 parts initiator;
[0016] The modified mesoporous silica is mesoporous silica modified by a fluorine-containing polybenzimidazole-silane coupling agent, and the silane coupling agent contains a carbon-carbon double bond.
[0017] Furthermore, the emulsifier is one or more of N-hexadecyl-N-ethylmorpholinyl ethyl sodium sulfate, pure sodium lauryl sulfate, polyoxyethylene monostearate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium ethoxylated fatty acid methyl ester sulfonate, and sodium secondary alkyl sulfonate.
[0018] Furthermore, the initiator is one or more of potassium persulfate and ammonium persulfate.
[0019] Furthermore, the preparation method of the modified mesoporous silica is:
[0020] Add mesoporous silica to the reactor, stir, and heat to 50-90°C. Mix the fluorinated polybenzimidazole-silane coupling agent, isopropyl alcohol, and deionized water and add them dropwise to the reactor. Adjust the pH to 5 and continue the reaction for 0.5-1.5 hours. After the reaction is completed, cool, wash, and dry to obtain modified mesoporous silica.
[0021] The dosage ratio of mesoporous silica, fluorinated polybenzimidazole-silane coupling agent, isopropyl alcohol and deionized water is 10 g: 1-3 g: 10-20 mL: 1-3 mL.
[0022] The -OH bonds of the hydrolyzed fluorinated polybenzimidazole-silane coupling agent react with the hydroxyl groups on the surface of the mesoporous silica to form Si-O-Si, thereby obtaining modified mesoporous silica. The modified mesoporous silica contains carbon-carbon double bonds and fluorinated polybenzimidazole. The modified mesoporous silica containing carbon-carbon double bonds can be evenly dispersed in the raw materials. Through in-situ polymerization, ceramic particles are grafted onto the prepared water-based adhesive molecular brush, resulting in the grafting of polymer molecular brushes with good compatibility onto the surface of the polyolefin diaphragm substrate, thereby improving the adhesion between the substrate and the ceramic particles. Mesoporous silica itself has the problem of poor dispersibility. Further modification can also improve the dispersibility of the mesoporous silica, which is beneficial for the modified mesoporous silica to exert its heat resistance.
[0023] Furthermore, the preparation method of the fluorinated polybenzimidazole-silane coupling agent is:
[0024] S1: Under argon protection, 2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-dicarboxylic acid, isophthalic acid, and 3,3',4,4'-benzenetetramine are added to polyphosphoric acid and stirred to mix uniformly, and the mixture is heated to 60°C for reaction for 8-9 hours, 120°C for reaction for 4-7 hours, and 250°C for reaction for 24 hours to obtain a polybenzimidazole solution; the solution is cooled and poured into water to obtain a polymer precipitate, and the polymer precipitate is washed and neutralized with a 5% mass concentration of NaHCO3 aqueous solution, and then washed with deionized water until neutral, and the precipitate is collected and dried to obtain a fluorinated polybenzimidazole;
[0025] The usage ratio of 2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-dicarboxylic acid, isophthalic acid, 3,3',4,4'-diphenyltetramine and polyphosphoric acid is 0.8-1.5g: 1-1.3g: 2.1g: 35-40g.
[0026] In the above steps, tetraamine monomer is ternarily copolymerized with isophthalic acid and dibasic acid containing trifluoromethyl groups to synthesize fluorinated polybenzimidazole containing trifluoromethyl side groups.
[0027] S2: Add fluorinated polybenzimidazole and sodium hydroxide to dimethyl sulfoxide, stir and activate at 60-75°C for 2-3 hours, then add vinyl (chloromethyl) dimethoxysilane, stir and react at 30-40°C for 36-40 hours, filter, and wash with anhydrous ethanol to obtain a fluorinated polybenzimidazole-silane coupling agent.
[0028] The usage ratio of fluorinated polybenzimidazole, sodium hydroxide, dimethyl sulfoxide and ethylene (chloromethyl) dimethoxysilane is 10g:4-7g:250mL:2.5-6g.
[0029] In the above steps, the fluorinated polybenzimidazole reacts with the chloromethyl group of vinyl(chloromethyl)dimethoxysilane under the activation of sodium hydroxide to obtain a fluorinated polybenzimidazole-silane coupling agent.
[0030] In a second aspect, the present invention provides a method for preparing an aqueous ceramic slurry for coating, comprising the following steps:
[0031] Isooctyl acrylate, methyl methacrylate, acrylonitrile, 2-ethylhexyl acrylate, acrylamide and modified mesoporous silica are mixed and stirred to obtain a mixed solution a; an emulsifier and deionized water are placed in a reactor and stirred evenly, and then the mixed solution a is added dropwise and stirred at 400-500 rpm to obtain a mixed solution b; an initiator is dissolved in deionized water, and the temperature is raised to 60-80°C and one-third of the designed amount of initiator solution is added dropwise, and nitrogen is introduced; after reacting for 30-50 minutes, one-third of the designed amount of initiator solution is continued to be added dropwise under a nitrogen atmosphere; after continuing the reaction for 30-50 minutes, one-third of the designed amount of initiator solution is added dropwise under a nitrogen atmosphere; under continuous stirring, the reaction is carried out for 3-5 hours, cooled, and the system is adjusted to pH = 7 with ammonia water to obtain a water-based ceramic slurry for coating.
[0032] In a third aspect, the present invention provides a battery separator comprising a base film and a ceramic coating formed on at least one side of the base film; the ceramic coating is made of the aqueous ceramic slurry described above or the aqueous ceramic slurry prepared by the preparation method described above.
[0033] Furthermore, the base film is a PE film or a PP film; the thickness of the base film is 3-6 μm.
[0034] Furthermore, the thickness of the ceramic coating is 0.5-3 μm.
[0035] Beneficial effects of the present invention:
[0036] The present invention incorporates modified mesoporous silica during the preparation of a water-based ceramic coating. The modified mesoporous silica is mesoporous silica modified with a fluorinated polybenzimidazole-silane coupling agent, wherein the modified silane coupling agent contains carbon-carbon double bonds. The modified mesoporous silica containing carbon-carbon double bonds can be uniformly dispersed in the raw materials. Through in-situ polymerization, ceramic particles are grafted onto the prepared water-based adhesive molecular brush, resulting in the grafting of a polymer molecular brush with good compatibility onto the surface of the polyolefin diaphragm substrate, thereby improving the adhesion between the substrate and the ceramic particles. Polybenzimidazole itself has high heat resistance. After being grafted onto the surface of the mesoporous silica, it is prepared into a ceramic slurry and coated on the surface of the base membrane, thereby improving the heat resistance of the diaphragm. The fluorinated polybenzimidazole contains trifluoromethyl groups, which themselves also have high heat resistance and can further enhance the heat resistance of the diaphragm. DETAILED DESCRIPTION
[0037] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.
[0038] Preparation Example 1
[0039] The preparation method of modified mesoporous silica is:
[0040] In a reaction kettle, 10 g of mesoporous silica was added, stirred, and heated to 60°C. 1 g of fluorine-containing polybenzimidazole-silane coupling agent, 20 mL of isopropyl alcohol and 2 mL of deionized water were mixed and then added dropwise into the reaction kettle. The pH was adjusted to 5, and the reaction was continued for 1.5 h. After the reaction was completed, the mixture was cooled, washed, and dried to obtain modified mesoporous silica.
[0041] The preparation method of the fluorine-containing polybenzimidazole-silane coupling agent is as follows:
[0042] S1: Under argon protection, 0.8 g of 2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-dicarboxylic acid, 1.3 g of isophthalic acid, and 2.1 g of 3,3',4,4'-biphenyltetramine were added to 40 g of polyphosphoric acid and stirred to mix uniformly. The mixture was heated to 60°C for 8 hours, 120°C for 6 hours, and 250°C for 24 hours to obtain a polybenzimidazole solution. The solution was cooled and then poured into water to obtain a polymer precipitate. The polymer precipitate was washed with a 5% NaHCO3 aqueous solution to neutralize, and then washed with deionized water until neutral. The precipitate was collected and dried to obtain a fluorine-containing polybenzimidazole.
[0043] S2: 10 g of fluorine-containing polybenzimidazole and 4 g of sodium hydroxide were added to 250 mL of dimethyl sulfoxide, and stirred at 60°C for 2 h. Then, 2.5 g of ethylene(chloromethyl)dimethoxysilane was added, and stirred at 40°C for 40 h. Filtration was performed, and the product was washed with anhydrous ethanol to obtain a fluorine-containing polybenzimidazole-silane coupling agent.
[0044] Preparation Example 2
[0045] The preparation method of the modified mesoporous silica is as follows:
[0046] In a reaction kettle, 10 g of mesoporous silica was added, stirred, and heated to 60°C. 1 g of fluorine-containing polybenzimidazole-silane coupling agent, 20 mL of isopropyl alcohol and 2 mL of deionized water were mixed and then added dropwise into the reaction kettle. The pH was adjusted to 5, and the reaction was continued for 1.5 h. After the reaction was completed, the mixture was cooled, washed, and dried to obtain modified mesoporous silica.
[0047] The preparation method of the fluorine-containing polybenzimidazole-silane coupling agent is as follows:
[0048] S1: Under argon protection, 1.1 g of 2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-dicarboxylic acid, 1.2 g of isophthalic acid, and 2.1 g of 3,3',4,4'-diphenyltetramine were added to 40 g of polyphosphoric acid and stirred to mix evenly. The mixture was heated to 60° C. for reaction for 8 hours, 120° C. for reaction for 6 hours, and 250° C. for reaction for 24 hours to obtain a polybenzimidazole solution; the solution was cooled and poured into water to obtain a polymer precipitate, and the polymer precipitate was washed and neutralized with a 5% mass concentration of NaHCO3 aqueous solution, and then washed with deionized water until neutral, and the precipitate was collected and dried to obtain a fluorinated polybenzimidazole;
[0049] S2: Add 10 g of fluorinated polybenzimidazole and 5 g of sodium hydroxide to 250 mL of dimethyl sulfoxide, stir and activate at 60°C for 2 h, then add 4.5 g of ethylene (chloromethyl) dimethoxysilane, stir and react at 40°C for 40 h, filter, and wash with anhydrous ethanol to obtain a fluorinated polybenzimidazole-silane coupling agent.
[0050] Preparation Example 3
[0051] The preparation method of modified mesoporous silica is:
[0052] Add 10 g of mesoporous silica to the reactor, stir, and heat to 60°C. Mix 3 g of fluorinated polybenzimidazole-silane coupling agent, 20 mL of isopropanol, and 2 mL of deionized water and add dropwise to the reactor. Adjust the pH to 5 and continue the reaction for 1.5 h. After the reaction is completed, cool, wash, and dry to obtain modified mesoporous silica.
[0053] The preparation method of fluorinated polybenzimidazole-silane coupling agent is as follows:
[0054] S1: Under argon protection, 1.5 g of 2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-dicarboxylic acid, 1 g of isophthalic acid, and 2.1 g of 3,3',4,4'-benzenetetramine were added to 40 g of polyphosphoric acid and stirred to mix evenly. The mixture was heated to 60° C. for reaction for 8 hours, 120° C. for reaction for 6 hours, and 250° C. for reaction for 24 hours to obtain a polybenzimidazole solution; the solution was cooled and poured into water to obtain a polymer precipitate, and the polymer precipitate was washed and neutralized with a 5% mass concentration of NaHCO3 aqueous solution, and then washed with deionized water until neutral, and the precipitate was collected and dried to obtain a fluorinated polybenzimidazole;
[0055] S2: Add 10 g of fluorinated polybenzimidazole and 7 g of sodium hydroxide to 250 mL of dimethyl sulfoxide, stir and activate at 75°C for 3 h, then add 6 g of ethylene (chloromethyl) dimethoxysilane, stir and react at 40°C for 40 h, filter, and wash with anhydrous ethanol to obtain a fluorinated polybenzimidazole-silane coupling agent.
[0056] Comparative Example 1
[0057] This comparative example is different from Preparation Example 1 in that the fluorinated polybenzimidazole is replaced with polybenzimidazole. The specific steps are as follows:
[0058] S1: Under argon protection, 1.7 g of isophthalic acid and 2.1 g of 3,3',4,4'-benzyltetramine were added to 40 g of polyphosphoric acid and stirred to mix evenly. The mixture was heated to 60° C. for reaction for 8 hours, 120° C. for reaction for 6 hours, and 250° C. for reaction for 24 hours to obtain a polybenzimidazole solution; the solution was cooled and poured into water to obtain a polymer precipitate, and the polymer precipitate was washed and neutralized with a 5% mass concentration of NaHCO3 aqueous solution, and then washed with deionized water until neutral, and the precipitate was collected and dried to obtain a fluorinated polybenzimidazole;
[0059] S2: Add 10 g of fluorinated polybenzimidazole and 4 g of sodium hydroxide to 250 mL of dimethyl sulfoxide, stir and activate at 60°C for 2 h, then add 2.5 g of vinyl (chloromethyl) dimethoxysilane, stir and react at 40°C for 40 h, filter, and wash with anhydrous ethanol to obtain a fluorinated polybenzimidazole-silane coupling agent. The remaining materials and steps are the same as those in Preparation Example 1.
[0060] Comparative Example 2
[0061] This comparative example differs from Preparation Example 1 in that the fluorinated polybenzimidazole is omitted. The specific steps are as follows:
[0062] 10 g of mesoporous silica was added to a reaction kettle, stirred, and heated to 60°C. A mixture of 1 g of vinyltrimethoxysilane, 20 mL of isopropanol, and 2 mL of deionized water was added dropwise to the reaction kettle. The pH was adjusted to 5, and the reaction was continued for 1.5 h. After the reaction, the mixture was cooled, washed, and dried to obtain modified mesoporous silica. The remaining raw materials and steps were the same as those in Preparation Example 1.
[0063] Example 1
[0064] 10 parts of isooctyl acrylate, 3 parts of methyl methacrylate, 0.2 parts of acrylonitrile, 5 parts of 2-ethylhexyl acrylate, 0.1 parts of acrylamide and 8 parts of modified mesoporous silica prepared in Preparation Example 1 were mixed and stirred to obtain a mixed solution a; 1 part of sodium lauryl sulfate and 70 parts of deionized water were placed in a reactor and stirred evenly, and then the mixed solution a was added dropwise and stirred at 500 rpm to obtain a mixed solution b; the temperature was raised to 80°C and one-third of the designed amount of a solution containing 1 part of potassium persulfate was slowly added dropwise, and nitrogen was introduced; after reacting for 40 minutes, one-third of the designed amount of initiator solution was continued to be added dropwise under a nitrogen atmosphere; after continuing the reaction for 40 minutes, one-third of the designed amount of initiator solution was added dropwise under a nitrogen atmosphere; the reaction was continued to stir for 5 hours, and the system was adjusted to pH = 7 with ammonia water to obtain a water-based ceramic slurry for coating; the water-based ceramic slurry was coated on one side of the PE film, and a battery separator was obtained after drying, with a base film thickness of 5 μm and a ceramic coating thickness of 1 μm.
[0065] Example 2
[0066] 10 parts of isooctyl acrylate, 3 parts of methyl methacrylate, 0.2 parts of acrylonitrile, 5 parts of 2-ethylhexyl acrylate, 0.1 parts of acrylamide and 9 parts of modified mesoporous silica prepared in Preparation Example 1 were mixed and stirred to obtain a mixed solution a; 1 part of sodium lauryl sulfate and 70 parts of deionized water were placed in a reactor and stirred evenly, and then the mixed solution a was added dropwise and stirred at 400 rpm to obtain a mixed solution b; the temperature was raised to 80°C and one-third of the designed amount of a solution containing 1 part of potassium persulfate was slowly added dropwise, and nitrogen was introduced; after reacting for 40 minutes, one-third of the designed amount of initiator solution was continued to be added dropwise under a nitrogen atmosphere; after continuing the reaction for 40 minutes, one-third of the designed amount of initiator solution was added dropwise under a nitrogen atmosphere; the reaction was continued to stir for 5 hours, and the system was adjusted to pH = 7 with ammonia water to obtain a water-based ceramic slurry for coating; the water-based ceramic slurry was coated on one side of the PE film, and a battery separator was obtained after drying, with a base film thickness of 5 μm and a ceramic coating thickness of 1 μm.
[0067] Example 3
[0068] 11 parts of isooctyl acrylate, 4 parts of methyl methacrylate, 0.3 parts of acrylonitrile, 5 parts of 2-ethylhexyl acrylate, 0.2 parts of acrylamide and 10 parts of modified mesoporous silica prepared in Preparation Example 2 were mixed and stirred to obtain a mixed solution a; 1.25 parts of sodium lauryl sulfate and 75 parts of deionized water were placed in a reactor and stirred evenly, and then the mixed solution a was added dropwise and stirred at 400-500rpm to obtain a mixed solution b; the temperature was raised to 80°C and one-third of the designed amount of a solution containing 1.5 parts of potassium persulfate was slowly added dropwise, and nitrogen was introduced; after reacting for 40 minutes, one-third of the designed amount of initiator solution was continued to be added dropwise under a nitrogen atmosphere; after continuing the reaction for 40 minutes, one-third of the designed amount of initiator solution was added dropwise under a nitrogen atmosphere; the reaction was continued to stir for 5 hours, and the system was adjusted to pH = 7 with ammonia water to obtain a water-based ceramic slurry for coating; the water-based ceramic slurry was coated on one side of the PE film, and a battery separator was obtained after drying, with a base film thickness of 5μm and a ceramic coating thickness of 1μm.
[0069] Example 4
[0070] 12 parts of isooctyl acrylate, 5 parts of methyl methacrylate, 0.4 parts of acrylonitrile, 5 parts of 2-ethylhexyl acrylate, 0.3 parts of acrylamide and 11 parts of modified mesoporous silica prepared in Preparation Example 3 were mixed and stirred to obtain a mixed solution a; 1.5 parts of sodium lauryl sulfate and 80 parts of deionized water were placed in a reactor and stirred evenly, and then the mixed solution a was added dropwise and stirred at 500 rpm to obtain a mixed solution b; the temperature was raised to 80°C and one-third of the designed amount of a solution containing 2 parts of potassium persulfate was slowly added dropwise, and nitrogen was introduced; after reacting for 40 minutes, one-third of the designed amount of initiator solution was continued to be added dropwise under a nitrogen atmosphere; after continuing the reaction for 40 minutes, one-third of the designed amount of initiator solution was added dropwise under a nitrogen atmosphere; the reaction was continued to stir for 5 hours, and the system was adjusted to pH = 7 with ammonia water to obtain a water-based ceramic slurry for coating; the water-based ceramic slurry was coated on one side of the PE film, and a battery separator was obtained after drying, with a base film thickness of 5 μm and a ceramic coating thickness of 1 μm.
[0071] Example 5
[0072] 12 parts of isooctyl acrylate, 5 parts of methyl methacrylate, 0.4 parts of acrylonitrile, 5 parts of 2-ethylhexyl acrylate, 0.3 parts of acrylamide and 12 parts of modified mesoporous silica prepared in Preparation Example 3 were mixed and stirred to obtain a mixed solution a; 1.5 parts of sodium lauryl sulfate and 80 parts of deionized water were placed in a reactor and stirred evenly, and then the mixed solution a was added dropwise and stirred at 500 rpm to obtain a mixed solution b; the temperature was raised to 80°C and one-third of the designed amount of a solution containing 2 parts of potassium persulfate was slowly added dropwise, and nitrogen was introduced; after reacting for 40 minutes, one-third of the designed amount of initiator solution was continued to be added dropwise under a nitrogen atmosphere; after continuing the reaction for 40 minutes, one-third of the designed amount of initiator solution was added dropwise under a nitrogen atmosphere; the reaction was continued to stir for 5 hours, and the system was adjusted to pH = 7 with ammonia water to obtain a water-based ceramic slurry for coating; the water-based ceramic slurry was coated on one side of the PE film, and a battery separator was obtained after drying, with a base film thickness of 5 μm and a ceramic coating thickness of 1 μm.
[0073] Comparative Example 1
[0074] Compared with Example 1, this comparative example is different in that the modified mesoporous silica prepared in Preparation Example 1 in Example 1 is replaced by the product in Control Example 1, and the remaining raw materials and steps are the same as in Example 1.
[0075] Comparative Example 2
[0076] Compared with Example 1, this comparative example is different in that the modified mesoporous silica prepared in Preparation Example 1 in Example 1 is replaced by the product in Control Example 2, and the remaining raw materials and steps are the same as in Example 1.
[0077] The thermal shrinkage test of the diaphragms prepared in Examples 1 to 5 and Comparative Examples 1 to 2 was performed: first, a 50×50 mm 2 A regularly shaped ceramic diaphragm was placed in an oven and baked at 130°C for 1 hour. Immediately after baking, the diaphragm's length (L) and width (W) were measured. The shrinkage ratio was calculated using the formula: η = (S - S1) / S = (1 - LW / 2500) × 100%, where S1 is the area of the diaphragm after baking and S is the area of the cut diaphragm. The test results are shown in Table 1.
[0078] Table 1
[0079]
[0080]
[0081] It can be seen from Table 1 that the heat resistance of the diaphragms prepared in Examples 1 to 5 is better than that in Comparative Examples 1 and 2.
[0082] The above disclosures are only a few specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present invention.
Claims
1. A water-based ceramic slurry for coating, characterized in that: It includes the following raw materials in parts by weight: 10-12 parts of isooctyl acrylate; 3-5 parts of methyl methacrylate; 0.2-0.4 parts of acrylonitrile; 5 parts of 2-ethylhexyl acrylate; 0.1-0.3 parts of acrylamide; 8-12 parts of modified mesoporous silica; 1-1.5 parts emulsifier; 70-80 parts deionized water; 1-2 parts initiator; The modified mesoporous silica is mesoporous silica modified by a fluorine-containing polybenzimidazole-silane coupling agent, and the silane coupling agent contains a carbon-carbon double bond.
2. The aqueous ceramic slurry for coating according to claim 1, characterized in that: The emulsifier is one or more of N-hexadecyl-N-ethylmorpholinyl ethyl sodium sulfate, pure sodium lauryl sulfate, polyoxyethylene monostearate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium ethoxylated fatty acid methyl ester sulfonate, and sodium secondary alkyl sulfonate.
3. The aqueous ceramic slurry for coating according to claim 1, characterized in that: The initiator is one or more of potassium persulfate and ammonium persulfate.
4. The aqueous ceramic slurry for coating according to claim 1, characterized in that: The preparation method of the modified mesoporous silica is: Add mesoporous silica to the reactor, stir, and heat to 50-90°C. Mix the fluorinated polybenzimidazole-silane coupling agent, isopropyl alcohol, and deionized water and add them dropwise to the reactor. Adjust the pH to 5 and continue the reaction for 0.5-1.5 hours. After the reaction is completed, cool, wash, and dry to obtain modified mesoporous silica.
5. The aqueous ceramic slurry for coating according to claim 4, characterized in that: The usage ratio of mesoporous silica, fluorinated polybenzimidazole-silane coupling agent, isopropyl alcohol and deionized water is 10g:1-3g:10-20mL:1-3mL.
6. The aqueous ceramic slurry for coating according to claim 4, characterized in that: The preparation method of the fluorinated polybenzimidazole-silane coupling agent is as follows: S1: Under argon protection, 2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-dicarboxylic acid, isophthalic acid, and 3,3',4,4'-benzenetetramine are added to polyphosphoric acid and stirred and mixed. The mixture is heated to 60°C for reaction for 8-9 hours, 120°C for reaction for 4-7 hours, and 250°C for reaction for 24 hours to obtain a polybenzimidazole solution; the solution is cooled and poured into water to obtain a polymer precipitate, and the polymer precipitate is washed and neutralized, washed, collected, and dried to obtain a fluorinated polybenzimidazole; S2: Add fluorinated polybenzimidazole and sodium hydroxide to dimethyl sulfoxide, stir and activate at 60-75°C for 2-3 hours, then add vinyl (chloromethyl) dimethoxysilane, stir and react at 30-40°C for 36-40 hours, filter, and wash with anhydrous ethanol to obtain a fluorinated polybenzimidazole-silane coupling agent.
7. The aqueous ceramic slurry for coating according to claim 6, characterized in that: In step S1, the usage ratio of 2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-dicarboxylic acid, isophthalic acid, 3,3',4,4'-diphenyltetramine, and polyphosphoric acid is 0.8-1.5 g: 1-1.3 g: 2.1 g: 35-40 g.
8. The aqueous ceramic slurry for coating according to claim 6, characterized in that: In step S2, the usage ratio of fluorinated polybenzimidazole, sodium hydroxide, dimethyl sulfoxide, and ethylene (chloromethyl) dimethoxysilane is 10 g: 4-7 g: 250 mL: 2.5-6 g.
9. A method for preparing a water-based ceramic slurry for coating, for preparing the water-based ceramic slurry according to any one of claims 1 to 8, characterized in that: The following steps are involved: Isooctyl acrylate, methyl methacrylate, acrylonitrile, 2-ethylhexyl acrylate, acrylamide, and modified mesoporous silica are mixed and stirred to obtain a mixed solution a; an emulsifier and deionized water are placed in a reactor and stirred evenly, and then the mixed solution a is added dropwise and stirred at 400-500 rpm to obtain a mixed solution b; an initiator is dissolved in deionized water, and the temperature is raised to 60°C-80°C, and one-third of the designed amount of the initiator solution is added dropwise, and nitrogen is introduced; after reacting for 30-50 minutes, one-third of the designed amount of the initiator solution is added dropwise under a nitrogen atmosphere; after continuing the reaction for 30-50 minutes, another one-third of the designed amount of the initiator solution is added dropwise under a nitrogen atmosphere; The mixture was reacted for 3-5 hours under continuous stirring, cooled, and the pH of the system was adjusted to 7 with aqueous ammonia to obtain a water-based ceramic slurry for coating.
10. A battery separator, characterized in that: The invention comprises a base film and a ceramic coating formed on at least one side of the base film; the ceramic coating is made of the aqueous ceramic slurry according to any one of claims 1 to 8, or the aqueous ceramic slurry prepared by the preparation method according to claim 9; The base film is a PE film or a PP film; the thickness of the base film is 3-6 μm; The thickness of the ceramic coating is 0.5-3 μm.