Water-soluble lithium ion battery ceramic diaphragm adhesive as well as preparation method and application thereof

Abstract

The invention relates to a water-soluble lithium ion battery ceramic diaphragm adhesive as well as a preparation method and application thereof, and belongs to the technical field of battery diaphragm adhesives. The technical problem to be solved by the invention is to provide the water-soluble lithium ion battery ceramic diaphragm adhesive. The adhesive comprises a polymer, and polymerization raw materials of the polymer comprise the following components in parts by weight: 1-30 parts of a water-soluble polymer component; 40 to 70 parts of an acrylamide monomer; 1-20 parts of a water-resistant monomer; 0-20 parts of a carboxyl or sulfonic monomer; and 0.01 to 0.5 part of an initiator. The adhesive disclosed by the invention has good water solubility, self-dispersibility, self-wettability and water absorption, can be smoothly coated on the surface of a base membrane and leveled, has good adhesive ability to powder ceramic and the base membrane, good heat resistance and water resistance, and is simple in preparation process, good in process and product stability, low in cost and suitable for industrial production. The production process can be effectively butted with the production process of the ceramic diaphragm slurry, and the production process flow of the lithium battery ceramic diaphragm is optimized.

Description

Technical Field

[0001] This invention relates to water-soluble lithium-ion battery ceramic separator adhesives, their preparation methods, and applications, belonging to the field of battery separator adhesive technology. Background Technology

[0002] Currently, lithium batteries primarily employ a ceramic coating on a polyolefin separator. This ceramic coating effectively improves the separator's heat resistance. The ceramic coating is mainly prepared using ceramics and water-based binders, and its quality directly impacts the performance of the final battery.

[0003] Existing lithium-ion battery ceramic separators primarily use emulsion-type waterborne adhesives with acrylate monomers as the main raw material. However, emulsion-type waterborne adhesives suffer from poor mechanical stability and storage stability. Furthermore, when using waterborne adhesives to formulate lithium-ion battery ceramic separator slurries, they exhibit poor dispersibility with water and ceramic powder, resulting in poor wetting performance of polyolefin-based membranes. Therefore, it is necessary to add dispersants, thickeners, wetting agents, and other additives to improve the stability of the slurry.

[0004] Compared to traditional double-sided coating, single-sided coating is a cost-effective design for industrial applications. Practical applications show that ceramic-coated separators prepared with single-sided coating also exhibit excellent overall performance. Currently, lithium-ion battery ceramic separators are becoming increasingly thin, resulting in poor heat and water resistance and significant appearance defects. Therefore, there is a need to develop a more stable solution-based aqueous adhesive that possesses self-dispersibility, self-wetting properties, and excellent heat and water resistance.

[0005] Chinese invention application CN110190235A discloses an aqueous solution-type ceramic separator adhesive for lithium batteries, its preparation method and application. The aqueous solution-type ceramic separator adhesive obtained by this patent has good self-dispersibility and self-wetting properties, but it fails to fully meet the requirements of ceramic separator adhesives for various properties such as water resistance, thermal stability and peel strength. Summary of the Invention

[0006] To address the above deficiencies, the technical problem solved by this invention is to provide a water-soluble lithium-ion battery ceramic separator adhesive, which, when applied to the separator, provides good water resistance.

[0007] The present invention relates to a water-soluble lithium-ion battery ceramic separator adhesive, comprising a polymer, wherein the polymer raw materials comprise the following components in parts by weight:

[0008] Water-soluble polymer component: 1–30 parts;

[0009] Acrylamide monomers: 40-70 parts;

[0010] Water-resistant monomer: 1-20 parts;

[0011] Carboxyl or sulfonic acid monomers: 0-20 parts;

[0012] Initiator: 0.01–0.5 parts;

[0013] The water-soluble polymer component includes at least one of polyvinyl alcohol, polyethylene glycol, sodium carboxymethyl cellulose, and hydroxyethyl cellulose; the acrylamide monomer includes at least one of acrylamide, methacrylamide, N-hydroxymethylacrylamide, N-hydroxyethylacrylamide, N,N′-dimethylacrylamide, N,N′-methylenebisacrylamide, N-methyl-2-acrylamide, and N-isopropylacrylamide; the water-resistant monomer includes at least one of acrylonitrile, methacrylonitrile, vinyl ethylene carbonate, vinylpyridine, and vinylthiophene; and the carboxyl or sulfonic acid monomer includes at least one polymerizable organic carboxylic acid or its salt, an anhydride of a polymerizable organic carboxylic acid or its salt after hydrolysis, or a sulfonic acid-containing monomer or its salt.

[0014] In one specific embodiment of the present invention, the carboxyl or sulfonic acid monomer comprises at least one of acrylic acid, methacrylic acid, crotonic acid, fumaric acid, 2-ethylacrylic acid, cis-butenedioic acid, lithium maleate, trans-butenedioic acid, 2-methylenesuccinic acid, trans-2-methyl-2-butenedioic acid, cis-2-methyl-2-butenedioic acid, propylene-1,2,3-tricarboxylic acid, 2-acrylamido-2-methylpropanesulfonic acid, vinyl sulfonic acid, allyl sulfonic acid, and p-styrene sulfonic acid.

[0015] In one specific embodiment of the present invention, the polymer raw materials comprise the following components in parts by weight: polyvinyl alcohol: 1-30 parts; acrylamide monomers: 40-70 parts; acrylonitrile: 1-20 parts; lithium maleate: 1-20 parts; initiator: 0.01-0.5 parts;

[0016] In one specific embodiment of the present invention, the polymer raw materials include the following components in parts by weight: polyvinyl alcohol: 21.5 parts; acrylamide monomers: 53.5 parts; acrylonitrile: 11 parts; lithium maleate: 13 parts; initiator: 0.01 to 0.5 parts.

[0017] In one specific embodiment of the present invention, the water-soluble lithium-ion battery ceramic separator adhesive further includes a solvent, wherein the solvent is water.

[0018] In a preferred embodiment, the solvent is deionized water.

[0019] In one specific embodiment of the present invention, the viscosity of the water-soluble lithium-ion battery ceramic separator adhesive is 5000 to 20000 cp, based on a solid content of 20%.

[0020] The present invention also provides a method for preparing the water-soluble lithium-ion battery ceramic separator adhesive described herein.

[0021] The present invention discloses a method for preparing a water-soluble lithium-ion battery ceramic separator adhesive, comprising the following steps:

[0022] 1) Dissolve the water-soluble polymer component in water to obtain a water-soluble polymer solution; dissolve the other components in the polymerization raw material, excluding the water-soluble polymer component, in water to obtain a monomer solution;

[0023] 2) Add the monomer solution to the water-soluble polymer solution to obtain the reaction solution, and then react for 5 to 20 hours to obtain the water-soluble lithium-ion battery ceramic separator adhesive.

[0024] In one specific embodiment of the present invention, in step 2), the monomer solution is added dropwise to the water-soluble polymer solution at a uniform rate, and the reaction temperature is 70-75°C.

[0025] In one specific embodiment of the present invention, in step 2), the pH value of the reaction solution is controlled to be 6.0 to 7.0.

[0026] The present invention also provides the application of the water-soluble lithium-ion battery ceramic separator adhesive described herein in the preparation of lithium battery ceramic separators.

[0027] This invention relates to a water-soluble lithium-ion battery ceramic separator adhesive, applicable to lithium-ion battery ceramic separators. This adhesive exhibits excellent wetting ability towards polyolefin-based membranes, allowing ceramic separator slurries prepared using this adhesive to be smoothly coated and leveled onto the base membrane surface. It also demonstrates good adhesion to powdered ceramics and the base membrane. When the slurry prepared with this adhesive is coated onto the base membrane surface and dries, it forms a uniform and dense powdered ceramic coating without any powdery or fragmentary shedding. Separators prepared using this adhesive, after treatment at 150°C for 1 hour, show a transverse and longitudinal thermal shrinkage rate of no more than 2%, and after immersion and stirring in deionized water, exhibit a water resistance exceeding 45%.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The adhesive of this invention has all raw materials with good water solubility, and the product is a homogeneous and transparent aqueous solution that can be diluted with water in any way and does not precipitate or separate after prolonged standing. It has good self-dispersibility and self-wetting properties. When ceramic diaphragm slurries are prepared using this adhesive, they can be smoothly coated onto the surface of the base membrane and leveled, reducing the need for dispersants, thickeners, wetting agents and other additives. It also has good water absorption; when the adhesive film is placed at 65% humidity for 7 days, the absorption rate does not exceed 3%.

[0030] The adhesive of this invention exhibits excellent dispersion ability for powdered ceramics, and the prepared ceramic diaphragm slurry shows no significant sedimentation after standing at room temperature for 24 hours. It also demonstrates good adhesion between the powdered ceramics and the base membrane; when the slurry prepared with this adhesive is coated onto the surface of the base membrane and dries, it forms a uniform and dense powdered ceramic coating without any powdery or fragmented shedding. Furthermore, it possesses good heat resistance; after treatment at 150°C for 1 hour, the diaphragm coated with the slurry prepared with this adhesive shows a transverse and longitudinal thermal shrinkage rate of no more than 2%. Finally, it exhibits good water resistance; after soaking and stirring in deionized water, the water resistance of the diaphragm exceeds 50%.

[0031] The adhesive of this invention uses an aqueous solution polymerization method, which has a simple preparation process, good process and product stability, and the production process can be effectively integrated with the production process of ceramic separator slurry, thus optimizing the production process of lithium battery ceramic separator. Detailed Implementation

[0032] The present invention relates to a water-soluble lithium-ion battery ceramic separator adhesive, comprising a polymer, wherein the polymer raw materials comprise the following components in parts by weight:

[0033] Water-soluble polymer component: 1–30 parts;

[0034] Acrylamide monomers: 40-70 parts;

[0035] Water-resistant monomer: 1-20 parts;

[0036] Carboxyl or sulfonic acid monomers: 0-20 parts;

[0037] Initiator: 0.01–0.5 parts;

[0038] The water-soluble polymer component includes at least one of polyvinyl alcohol, polyethylene glycol, sodium carboxymethyl cellulose, and hydroxyethyl cellulose; the acrylamide monomer includes at least one of acrylamide, methacrylamide, N-hydroxymethylacrylamide, N-hydroxyethylacrylamide, N,N′-dimethylacrylamide, N,N′-methylenebisacrylamide, N-methyl-2-acrylamide, and N-isopropylacrylamide; the water-resistant monomer includes at least one of acrylonitrile, methacrylonitrile, vinyl ethylene carbonate, vinylpyridine, and vinylthiophene; and the carboxyl or sulfonic acid monomer includes at least one polymerizable organic carboxylic acid or its salt, an anhydride of a polymerizable organic carboxylic acid or its salt after hydrolysis, or a sulfonic acid-containing monomer or its salt.

[0039] This invention relates to a water-soluble lithium-ion battery ceramic separator adhesive, which is polymerized from specific raw materials. The product is water-soluble and not only meets the requirements of lithium batteries for heat resistance, adhesion, and low water absorption in ceramic separator adhesives, but also possesses self-dispersibility, self-wetting ability, and water resistance. It exhibits good dispersion ability for powdered ceramics and wetting ability for polyolefin-based membranes, and the coated separator demonstrates excellent water resistance.

[0040] In one specific embodiment of the present invention, the carboxyl or sulfonic acid monomer comprises at least one of acrylic acid, methacrylic acid, crotonic acid, fumaric acid, 2-ethylacrylic acid, cis-butenedioic acid, lithium maleate, trans-butenedioic acid, 2-methylenesuccinic acid, trans-2-methyl-2-butenedioic acid, cis-2-methyl-2-butenedioic acid, propylene-1,2,3-tricarboxylic acid, 2-acrylamido-2-methylpropanesulfonic acid, vinyl sulfonic acid, allyl sulfonic acid, and p-styrene sulfonic acid.

[0041] In one specific embodiment of the present invention, the polymer raw materials comprise the following components in parts by weight: polyvinyl alcohol: 1-30 parts; acrylamide monomers: 40-70 parts; acrylonitrile: 1-20 parts; lithium maleate: 1-20 parts; initiator: 0.01-0.5 parts;

[0042] In one specific embodiment of the present invention, the polymer raw materials include the following components in parts by weight: polyvinyl alcohol: 21.5 parts; acrylamide monomers: 53.5 parts; acrylonitrile: 11 parts; lithium maleate: 13 parts; initiator: 0.01 to 0.5 parts.

[0043] The initiator described in this invention is a commonly used initiator in the field, including but not limited to peroxides such as ammonium persulfate and potassium persulfate, and azo initiators such as azobisisobutyronitrile can also be used.

[0044] In one specific embodiment of the present invention, the water-soluble lithium-ion battery ceramic separator adhesive further includes a solvent, wherein the solvent is water.

[0045] In a preferred embodiment, the solvent is deionized water.

[0046] In one specific embodiment of the present invention, the viscosity of the water-soluble lithium-ion battery ceramic separator adhesive is 5000 to 20000 cp, based on a solid content of 20%.

[0047] The present invention also provides a method for preparing the water-soluble lithium-ion battery ceramic separator adhesive described herein.

[0048] The present invention discloses a method for preparing a water-soluble lithium-ion battery ceramic separator adhesive, comprising the following steps:

[0049] 1) Dissolve the water-soluble polymer component in water to obtain a water-soluble polymer solution; dissolve the other components in the polymerization raw material, excluding the water-soluble polymer component, in water to obtain a monomer solution;

[0050] 2) Add the monomer solution to the water-soluble polymer solution to obtain the reaction solution, and then react for 5 to 20 hours to obtain the water-soluble lithium-ion battery ceramic separator adhesive.

[0051] In one specific embodiment of the present invention, in step 2), the monomer solution is added dropwise to the water-soluble polymer solution at a uniform rate, and the reaction temperature is 70-75°C.

[0052] In one specific embodiment of the present invention, in step 2), the pH value of the reaction solution is controlled to be 6.0 to 7.0.

[0053] The present invention also provides the application of the water-soluble lithium-ion battery ceramic separator adhesive described herein in the preparation of lithium battery ceramic separators.

[0054] This invention relates to a water-soluble lithium-ion battery ceramic separator adhesive, applicable to lithium-ion battery ceramic separators. This adhesive exhibits excellent wetting ability towards polyolefin-based membranes, allowing ceramic separator slurries prepared using this adhesive to be smoothly coated and leveled onto the base membrane surface. It also demonstrates good adhesion to powdered ceramics and the base membrane. When the slurry prepared with this adhesive is coated onto the base membrane surface and dries, it forms a uniform and dense powdered ceramic coating without any powdery or fragmentary shedding. Separators prepared using this adhesive, after treatment at 150°C for 1 hour, show a transverse and longitudinal thermal shrinkage rate of no more than 2%, and after immersion and stirring in deionized water, exhibit a water resistance exceeding 45%.

[0055] The specific embodiments of the present invention will be further described below with reference to examples, but the present invention is not limited to the scope of the embodiments described herein.

[0056] The polyvinyl alcohol used in the examples had a degree of alcoholysis of 70.0–100.0%, a viscosity of 20.0–200.0 mPa·s, and a pH of 5–7. Sodium carboxymethyl cellulose had a viscosity of 3000–5000 mPa·s, a pH of 6.0–8.5, and a degree of substitution (M / C6) of 0.65–0.75. Hydroxyethyl cellulose had a viscosity of 140–150 mPa·s and a pH of 6.0–8.0.

[0057] Example 1

[0058] (1) By weight, the following proportions of raw materials are prepared: polyvinyl alcohol 4.3%, lithium maleate 2.6%, acrylonitrile 2.2%, acrylamide 10.7%, initiator (ammonium persulfate) 0.2%, and the remainder is water (all deionized water);

[0059] The water is divided into two parts: the first part accounts for 47% of the total water volume, and the second part accounts for 53% of the total water volume, which are to be used later.

[0060] (2) Add polyvinyl alcohol and the first portion of water into a reaction flask, heat to 95°C and stir until completely dissolved, cool the polyvinyl alcohol solution to 70°C and continue stirring, and set aside for use;

[0061] (3) After dissolving lithium maleate, acrylonitrile, and acrylamide in the second part of water, add ammonium persulfate and stir until completely dissolved, then set aside for use;

[0062] (4) The liquid from step (3) is added dropwise to the liquid from step (2) at a uniform rate using a vacuum peristaltic pump over a period of 1 hour. After the addition is complete, the pH of the reaction solution is maintained at 6.0–7.0, and the temperature is maintained at 70–75°C for another 10 hours with stirring. The mixture is then cooled and collected. The resulting product is a yellow, transparent, homogeneous aqueous solution with a viscosity of approximately 7000 cp and a solid content of 20%.

[0063] Example 2

[0064] Example 2 involves directly pouring the liquid from step (3) of Example 1 into step (2), and stirring at 70-75°C for 10 hours. After cooling, the product is collected as a yellowish-brown transparent aqueous solution with a viscosity of approximately 10,000 cp and a solid content of 20%.

[0065] Example 3

[0066] Example 3 differs from Example 1 in that it uses carboxyl or sulfonic acid monomers accounting for 2.3% of the total monomers. The pH of the reaction solution is monitored by a pH meter to be 5-6, and the product is a yellowish-brown transparent aqueous solution with a viscosity of about 12000 cp and a solid content of 20%.

[0067] Examples 4-11

[0068] The difference from Example 1 is that the polymerization raw materials are changed, and the specific changes are shown in Table 1.

[0069] Table 1

[0070]

[0071] Comparative Example 1

[0072] The difference between Comparative Example 1 and Example 1 is that 2.2% of acrylonitrile was replaced with an equal amount of deionized water, resulting in a yellow transparent aqueous solution with a viscosity of about 7000 cp and a solid content of 18%.

[0073] Comparative Example 2

[0074] The comparative example differs from Example 1 in that the water-soluble polymer is blended with the polymerized monomer, i.e., it is prepared according to the following method:

[0075] (1) By weight, the following proportions of raw materials are prepared: polyvinyl alcohol 4.3%, lithium maleate 2.6%, acrylonitrile 2.2%, acrylamide 10.7%, initiator (ammonium persulfate) 0.2%, and the remainder is water (all deionized water);

[0076] The water is divided into two parts: the first part accounts for 47% of the total water volume, and the second part accounts for 53% of the total water volume, which are to be used later.

[0077] (2) Add polyvinyl alcohol and the first portion of water into a reaction flask, heat to 95°C and stir until completely dissolved, cool the polyvinyl alcohol solution to 70°C and continue stirring, and set aside for use;

[0078] (3) After dissolving lithium maleate, acrylonitrile, and acrylamide in the second part of water, add ammonium persulfate and stir until completely dissolved. The pH of the reaction solution is 6.0 to 7.0, and the solution is kept at 70 to 75°C and stirred for 10 hours.

[0079] (4) Mix the liquid from step (2) and the liquid from step (3) thoroughly. The resulting product is a yellow, semi-transparent, homogeneous aqueous solution.

[0080] The physicochemical properties of the adhesive prepared above are shown in Table 2.

[0081] Table 2

[0082] serial number Appearance Solid content % Viscosity cp Placed at room temperature for 7 days Film water absorption rate % Example 1 Yellow, transparent, homogeneous aqueous solution 20 7000 No sediment 2.4 Example 2 Yellowish-brown transparent aqueous solution 19.7 10000 No sediment 2.5 Example 3 Yellowish-brown transparent aqueous solution 20 12000 No sediment 2.0 Example 4 Yellow transparent aqueous solution 20 8000 No sediment 3.0 Example 5 Yellow transparent aqueous solution 20 8500 No sediment 2.8 Example 6 Yellowish-brown transparent aqueous solution 20 15000 No sediment 2.8 Example 7 Yellow transparent aqueous solution 20 7000 No sediment 2.5 Example 8 Yellow transparent aqueous solution 20 7000 No sediment 2.8 Example 9 Yellow transparent aqueous solution 20 8000 No sediment 2.8 Example 10 Yellow transparent aqueous solution 20 8000 No sediment 2.6 Example 11 Yellow transparent aqueous solution 20 8000 No sediment 2.6 Comparative Example 1 Yellow transparent aqueous solution 18 7000 No sediment 8.5 Comparative Example 2 Yellow transparent aqueous solution 20 6000 No sediment 5.0

[0083] The viscosity measurement method is as follows: The temperature in the constant temperature bath is raised to 25℃ and maintained at this temperature. Approximately 350g of the sample to be tested is poured into a clean, dry measuring cup, sealed with the rubber stopper of a thermometer, and then placed in the constant temperature bath for heating until the sample reaches 25℃ (stirring approximately every 5 minutes to ensure uniform concentration and temperature within the sample), and then maintained at this temperature for another 10 minutes before testing. The sample, heated to 25℃, is then tested using a digital viscometer with a 64-gauge rotor at 30 rpm for 3 minutes. Data is collected by averaging single-point measurements.

[0084] The method for determining water absorption rate is as follows: Weigh the dried film and record the weight as M1; place the film at 65% humidity for 7 days and record the weight as M2.

[0085] Water absorption rate = (M2 - M1 / ​​M1 * 100%)

[0086] Preparation method of adhesive film: Pour the adhesive liquid evenly into a fixed circular mold, place it in a forced-air drying oven, and dry at 70℃ for 12 hours.

[0087] Test case

[0088] The adhesives prepared in the above examples and comparative examples were applied to ceramic diaphragms.

[0089] The preparation method of the ceramic diaphragm includes the following steps:

[0090] Basic ceramic slurry formulation: 97 parts ceramic powder and 3 parts binder are mixed to form a ceramic slurry with a solid content of 38%. The slurry is dispersed using a top-mounted electric stirrer equipped with a four-blade impeller at a speed of 800–1000 rpm for 30–60 minutes to obtain the ceramic diaphragm slurry. Then, using a polyolefin (PE) diaphragm as the substrate, a ceramic slurry coating of approximately 2 μm thickness is applied to obtain a diaphragm with a ceramic coating (referred to as a ceramic diaphragm). The basic properties of the ceramic diaphragm are then tested.

[0091] 1. Testing Method

[0092] (1) Thickness

[0093] Sampling method: Cut a rectangular sample, 1m in length and the width of a small roll.

[0094] Test method: After flattening the sample, use a micrometer to randomly select points at the top, middle and bottom to measure.

[0095] Data processing: Record the measured thickness values ​​at each point and calculate the arithmetic mean of the thickness at each point.

[0096] (2) Surface density

[0097] Sampling methods: Base membrane areal density: Cut a circular diaphragm sample with a diameter of d = 86 mm. Finished product areal density: Cut a circular diaphragm sample with a diameter of d = 86 mm.

[0098] Test method: Weigh a sample with a mass m using an electronic balance with an accuracy of 0.001g, measure the sample area S, and calculate its surface density according to formula (Ⅰ).

[0099] Formula (I):

[0100] In equation (Ⅰ), BW is the areal density, with units of g / cm³. 2 m represents the mass of one sample layer in grams; S represents the area of ​​one sample layer in centimeters. 2 BW0 represents the surface density of the PE diaphragm.

[0101] (3) Thermal shrinkage

[0102] Sampling method: Cut rectangular samples with a blade. The width of the product (small roll width, ≤500mm) is used as the length of the TD (Transverse Direction, i.e., perpendicular to the machine direction or transverse direction) for heat shrinkage rate testing. Cut 100mm along the length of the product as the length of the MD (Machine Direction, mechanical stretching direction or longitudinal direction) for heat shrinkage rate testing.

[0103] Test Method: Heat the sample in an electric constant temperature chamber to the specified temperature. Measure and record the longitudinal and transverse dimensions of each sample, and number them. Place the sample evenly and flat within the paper sleeve layers (5 layers in total). Ensure the sample is free of folds, wrinkles, and adhesions. Heat the electric constant temperature chamber to the specified temperature, and place the paper sleeve containing the product flat in the center of the constant temperature chamber. Start timing after the chamber reaches the specified temperature. After maintaining the temperature for the specified duration, remove the sample. Cool to the ambient temperature and measure the longitudinal and transverse lengths. Calculate the heat shrinkage rate according to formula (II). Record the heat shrinkage rate of each sample and calculate the arithmetic mean of all samples.

[0104] Formula (II):

[0105] In formula (II), T is the thermal shrinkage rate of the sample, in %; L0 is the length of the sample before heating, in mm; and L is the length of the sample after heating, in mm.

[0106] (4) Peeling force

[0107] Sampling method: Cut rectangular samples with a width of 45mm and a length of ≥120mm.

[0108] Test method: The sample is evenly and flatly attached to a steel plate with a width greater than 25 mm and a length of 120 mm (the surface roughness of the steel plate is 50±25 nm) with double-sided tape. The long side of the sample is pulled away from the test plate by 3-8 mm in the opposite direction, so that the sample is completely separated from the test plate in the width direction. Then the sample and the test plate are fixed on the peel test machine for testing. The preload speed is 20 mm / min, the test speed is 300 mm / min, and the test ends when the displacement is 40-50 mm.

[0109] Data processing: Record the average peel force value of the sample.

[0110] (5) Moisture content:

[0111] Sampling method: Cut a rectangular sample about 30mm long and 20mm wide with scissors, put it into an electronic balance, weigh it and record the weight. The weighing range is 0.02 to 0.2 parts.

[0112] Test method: Set the heating furnace temperature to 150℃ and the termination time to 500s on the main interface of the titration station. Check whether the water reagent is sufficient (100mL). Under normal conditions, it is a light yellow transparent liquid. Check whether the sealing of all parts of the instrument is good. Check whether the electronic balance bubble level is in the center position and zeroed normally.

[0113] Data processing: Record water content test values.

[0114] (6) Water resistance rate after soaking in water for 10 minutes

[0115] Sampling method: Cut a circular diaphragm sample with d = 86 mm and weigh it. Pour deionized water into a beaker and place a magnetic stir bar to stir the water to create a vortex. Put the circular sample into the beaker and stir for 10 minutes. Remove it, hang it to dry, and weigh it.

[0116] Calculate the water resistance rate according to formula (Ⅲ).

[0117] Formula (III):

[0118] Where M1 is the weight of the diaphragm after coating with slurry, M2 is the weight of the diaphragm after being stirred in water for 10 minutes and then suspended and dried, and M0 is the weight of the base membrane.

[0119] 2. Test Results

[0120] The basic properties of the ceramic diaphragms prepared in each embodiment and comparative example are shown in Table 3.

[0121] Table 3

[0122]

[0123]

[0124] It is evident that the adhesive of the present invention has excellent properties and can be used in the preparation of ceramic diaphragms.

Claims

1. A water-soluble ceramic separator adhesive for lithium-ion batteries, characterized in that: The polymer comprises a polymer, wherein the polymeric raw material comprises the following components in parts by weight: Water-soluble polymer component: 1–30 parts; Acrylamide monomers: 40-70 parts; Water-resistant monomer: 1-20 parts; Carboxyl or sulfonic acid monomers: 0-20 parts; Initiator: 0.01–0.5 parts; The water-soluble polymer component includes at least one of polyvinyl alcohol, polyethylene glycol, sodium carboxymethyl cellulose, and hydroxyethyl cellulose; the acrylamide monomer includes at least one of acrylamide, methacrylamide, N-hydroxymethyl acrylamide, N-hydroxyethyl acrylamide, N,N′-dimethyl acrylamide, N,N′-methylenebisacrylamide, N-methyl-2-acrylamide, and N-isopropylacrylamide; the water-resistant monomer includes at least one of acrylonitrile, methacrylonitrile, vinyl ethylene carbonate, vinylpyridine, and vinylthiophene; and the carboxyl or sulfonic acid monomer includes at least one of polymerizable organic carboxylic acids or their salts, anhydrides of polymerizable organic carboxylic acids or their salts obtained after hydrolysis, and sulfonic acid-containing monomers or their salts.

2. The water-soluble lithium-ion battery ceramic separator adhesive according to claim 1, characterized in that: The carboxyl or sulfonic acid monomers include at least one of acrylic acid, methacrylic acid, crotonic acid, fumaric acid, 2-ethylacrylic acid, cis-butenedioic acid, lithium maleate, trans-butenedioic acid, 2-methylenesuccinic acid, trans-2-methyl-2-butenedioic acid, cis-2-methyl-2-butenedioic acid, propylene-1,2,3-tricarboxylic acid, 2-acrylamido-2-methylpropanesulfonic acid, vinyl sulfonic acid, allyl sulfonic acid, and p-styrene sulfonic acid.

3. The water-soluble lithium-ion battery ceramic separator adhesive according to claim 1, characterized in that: The polymer raw materials comprise the following components in parts by weight: Polyvinyl alcohol: 1-30 parts; Acrylamide monomers: 40-70 parts; Acrylonitrile: 1-20 parts; Lithium maleate: 0-20 parts; Initiator: 0.01–0.5 parts; More preferably, the polymer raw materials comprise the following components in parts by weight: polyvinyl alcohol: 21.5 parts; acrylamide monomers: 53.5 parts; Acrylonitrile: 11 parts; Lithium maleate: 13 parts; Initiator: 0.01 to 0.5 parts.

4. The water-soluble lithium-ion battery ceramic separator adhesive according to claim 1, characterized in that: The water-soluble lithium-ion battery ceramic separator adhesive also includes a solvent, wherein the solvent is water; preferably, the solvent is deionized water.

5. The water-soluble lithium-ion battery ceramic separator adhesive according to claim 1, characterized in that: With a solid content of 20%, the viscosity of this water-soluble lithium-ion battery ceramic separator adhesive is 5000-20000 cp.

6. The method for preparing the water-soluble lithium-ion battery ceramic separator adhesive according to any one of claims 1 to 5, characterized in that, Includes the following steps: 1) Dissolve the water-soluble polymer component in water to obtain its solution; The monomer solution is obtained by dissolving the components of the polymer raw material other than the water-soluble polymer component in water. 2) Add the monomer solution to the water-soluble polymer solution to obtain the reaction solution, and then react for 5 to 20 hours to obtain the water-soluble lithium-ion battery ceramic separator adhesive.

7. The method for preparing the water-soluble lithium-ion battery ceramic separator adhesive according to claim 6, characterized in that: In step 2), the monomer solution is added dropwise to the water-soluble polymer solution at a uniform rate, and the reaction temperature is 70-75℃.

8. The method for preparing the water-soluble lithium-ion battery ceramic separator adhesive according to claim 6, characterized in that: In step 2), the pH of the reaction solution is controlled to be 6.0 to 7.0 by adding carboxyl or sulfonic acid monomers and using a pH meter to monitor and adjust the pH.

9. The application of the water-soluble lithium-ion battery ceramic separator adhesive according to any one of claims 1 to 5 in the preparation of lithium battery ceramic separators.

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