A water-resistant soap-free emulsion with high glass transition temperature, a ceramic diaphragm and its application

Abstract

The present invention belongs to the technical field of lithium batteries, and provides a water-resistant soap-free emulsion with a high glass transition temperature, a ceramic diaphragm and applications thereof. The water-resistant soap-free emulsion with a high glass transition temperature of the present invention comprises a basic monomer, a high glass transition temperature monomer, a water-resistant monomer, an initiator, a neutralizer and water, wherein specific basic monomers, high glass transition temperature monomers and water-resistant monomers are used as monomer materials. The water-resistant soap-free emulsion provided by the present invention can be used as an adhesive for a ceramic diaphragm, and the ceramic diaphragm prepared therefrom has good heat resistance, good water resistance, high hardness, good performance in oil-based coating, and strong ceramic coating peeling force. The adhesive is used to prepare a ceramic diaphragm, and is further used to prepare a lithium battery. The prepared lithium battery has a high 700T capacity retention rate at 45°C, a low thickness expansion rate, and excellent battery performance.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and more specifically to a water-resistant soap-free emulsion with a high glass transition temperature, a ceramic diaphragm and applications thereof. Background Art

[0002] At present, the surface of the ceramic diaphragm used in lithium batteries is coated with a ceramic coating, and the ceramic coating is mainly made of ceramic and water-based adhesive. At present, the water-based adhesive is mainly made of emulsion polymerization containing emulsifiers. Since it contains more emulsifiers, it has a certain impact on battery performance. At the same time, due to the presence of emulsifiers, more bubbles will be generated when the ceramic slurry refluxes at high speed, affecting the coating of the ceramic coating. In addition, since the ceramic diaphragms currently used are getting thinner and thinner (the PE diaphragms prepared by the wet method are currently in mass production, and their thickness is only about 4μm), the heat resistance of the ceramic diaphragms has decreased, and the appearance of poor appearance has become more and more serious, such as treading and water ripples. In addition, during the post-processing of lithium battery separators, oily polyvinylidene fluoride (PVDF) needs to be coated. The specific process is: a layer of PVDF solution with dimethylacetamide (DMAC) or N-methylpyrrolidone (NMP) as solvent is coated on the ceramic coating. The solvent is generally removed by water washing, that is, after the PVDF coating is coated on the ceramic coating, it is immediately extracted in a water tank to remove the solvent. This process takes about 30 minutes (50m / min). If the ceramic coating has poor water resistance, the coating will fall off completely. Therefore, the ceramic coating is also required to have a certain degree of water resistance.

[0003] As the ceramic diaphragms of lithium batteries are becoming thinner and thinner, their heat resistance and water resistance are poor and their appearance is seriously bad. Therefore, there is an urgent need to develop an adhesive for ceramic diaphragms to further produce ceramic diaphragms with good heat resistance, appearance performance and water resistance. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a water-resistant soap-free emulsion with a high glass transition temperature, a ceramic diaphragm and its application. The water-resistant soap-free emulsion provided by the present invention has a high glass transition temperature and can be used as an adhesive for ceramic diaphragms to prepare ceramic diaphragms. The prepared ceramic diaphragms have good heat resistance, water resistance and good appearance performance. The ceramic diaphragm is further used to prepare lithium batteries. The prepared lithium batteries have a high 700T capacity retention rate at 45°C, which is greater than 87.00%, and can even reach 89.00%, while the thickness expansion rate is low, not higher than 9.87%, and can even be as low as 9.27%, and the battery performance is excellent.

[0005] The first aspect of the present invention provides a water-resistant soap-free emulsion with a high glass transition temperature.

[0006] Specifically, a water-resistant soap-free emulsion with a high glass transition temperature comprises the following raw material components:

[0007] Basic monomer,

[0008] High glass transition temperature monomers,

[0009] Water-resistant monomer,

[0010] Initiator,

[0011] Neutralizer,

[0012] water;

[0013] The base monomer includes at least one of methacrylic acid, acrylic acid, methyl methacrylate, butyl acrylate, isooctyl acrylate, glycidyl methacrylate, and itaconic acid;

[0014] The high glass transition temperature monomer includes at least one of acrylamide (Tg is 165°C), tricyclodecane diacrylate (Tg is 235°C), and pentaerythritol tritetraacrylate (Tg is 275°C);

[0015] The water-resistant monomer includes at least one of versatate vinyl carbonate, lauryl acrylate and octadecyl acrylate.

[0016] The present invention uses basic monomers, high glass transition temperature monomers, water-resistant monomers, initiators, and neutralizers as the main raw material components of the water-resistant soap-free emulsion, wherein three monomers such as specific types of basic monomers, high glass transition temperature monomers, and water-resistant monomers are used to prepare polymer components. The basic monomers selected by the present invention can mainly provide flexibility and adhesion; the selected high glass transition temperature monomers can mainly provide heat resistance and help improve the stiffness of the diaphragm; when the water-resistant soap-free emulsion is further used as an adhesive for the diaphragm, the water-resistant monomers therein can provide good water resistance. The water-resistant soap-free emulsion provided by the present invention can be used as an adhesive for the diaphragm and used to prepare the ceramic coating of the diaphragm. The use of a high glass transition temperature adhesive can improve the heat resistance of the ceramic coating, thereby improving the heat resistance of the diaphragm. In addition, the addition of an adhesive with a high glass transition temperature can also effectively improve the appearance performance of the diaphragm, mainly because: lithium battery diaphragms are generally porous polyethylene (PE) films, which are formed by biaxial stretching. During this process, if there is a slight fluctuation, the quality of the diaphragm will have appearance defects such as treading and water ripples. When a high glass transition temperature adhesive is used to coat the ceramic diaphragm, due to the high glass transition temperature of the adhesive itself, at room temperature, the adhesive is in a glassy state with very high hardness and stiffness. Therefore, when the adhesive of the present invention is used to coat the ceramic diaphragm, the diaphragm can be given good hardness and stiffness, thereby reducing the appearance of defects such as treading and water ripples in the ceramic diaphragm.

[0017] Preferably, the base monomer includes at least one of methacrylic acid, acrylic acid and itaconic acid.

[0018] Preferably, the water-resistant monomer is lauryl acrylate.

[0019] Preferably, the initiator includes at least one of ammonium persulfate, sodium bisulfite and potassium persulfate.

[0020] More preferably, the initiator is ammonium persulfate.

[0021] Preferably, the neutralizing agent includes at least one of sodium bicarbonate, sodium hydroxide and ammonia water.

[0022] Preferably, the water is deionized water.

[0023] Further preferably, the neutralizing agent comprises sodium hydroxide and / or aqueous ammonia.

[0024] Preferably, the following components are included in parts by mass:

[0025]

[0026] More preferably, the following components are included in parts by mass:

[0027]

[0028] The second aspect of the present invention provides a method for preparing a water-resistant soap-free emulsion with a high glass transition temperature.

[0029] A method for preparing a water-resistant soap-free emulsion with a high glass transition temperature comprises the following steps:

[0030] Firstly, a neutralizer, part of the basic monomer and part of the water are mixed, and a protective gas is introduced; then part of the initiator is added to initiate the reaction, and a high glass transition temperature monomer, a water-resistant monomer, the remaining basic monomer and the remaining water are added dropwise, and at the same time, the remaining initiator is added dropwise, and the reaction is carried out by heat preservation to obtain the water-resistant soap-free emulsion.

[0031] The invention first mixes part of the basic monomer, the neutralizer and part of the water, adds part of the initiator to initiate the reaction in a protective gas atmosphere, then adds the high glass transition temperature monomer, the water-resistant monomer, and the remaining basic monomer, the initiator and water to prepare the water-resistant soap-free emulsion. No emulsifier needs to be added during the reaction. The preparation method of the invention is simple and easy to operate, and is helpful to prepare the water-resistant soap-free emulsion with good water resistance and high glass transition temperature.

[0032] Preferably, the method for preparing the water-resistant soap-free emulsion comprises the following steps:

[0033] Firstly, a basic monomer accounting for 1-15% of the total mass of the basic monomer, a neutralizer and water accounting for 40% of the total mass of the water are mixed, a protective gas is introduced, an initiator accounting for 40-60% of the total mass of the initiator is added to initiate a reaction, the remaining basic monomer, a high glass transition temperature monomer, a water-resistant monomer and the remaining water are added dropwise, and the remaining initiator is added dropwise at the same time, and the reaction is carried out by heat preservation to obtain the water-resistant soap-free emulsion.

[0034] Preferably, the protective gas is nitrogen.

[0035] The third aspect of the present invention provides an application of a water-resistant soap-free emulsion with a high glass transition temperature.

[0036] Application of a water-resistant soap-free emulsion with a high glass transition temperature in the preparation of ceramic diaphragms.

[0037] A ceramic diaphragm adhesive comprises the water-resistant soap-free emulsion with a high glass transition temperature.

[0038] A ceramic diaphragm comprises a ceramic coating and a diaphragm substrate. The raw material components for preparing the ceramic coating include the adhesive for the ceramic diaphragm, ceramic powder, carboxymethyl cellulose, a wetting agent and a dispersant.

[0039] Preferably, the ceramic diaphragm comprises the following raw material components in parts by mass:

[0040]

[0041] More preferably, the ceramic diaphragm comprises the following raw material components:

[0042]

[0043] Preferably, the wetting agent includes at least one of lauryl alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, and dioctyl sodium sulfosuccinate.

[0044] Preferably, the dispersant comprises sodium polyacrylate and / or sodium polymethacrylate.

[0045] Preferably, the diaphragm substrate is a porous polyethylene (PE) diaphragm.

[0046] Preferably, the thickness of the diaphragm substrate is 1-20 μm.

[0047] More preferably, the thickness of the diaphragm substrate is 5-12 μm.

[0048] More preferably, the thickness of the separator substrate is 5 μm, 7 μm, 9 μm or 12 μm.

[0049] A method for preparing a ceramic diaphragm comprises the following steps:

[0050] The ceramic diaphragm adhesive, ceramic powder, carboxymethyl cellulose, a wetting agent, and a dispersant are mixed to form a ceramic slurry, which is then coated on a diaphragm substrate.

[0051] Preferably, the solid content of the ceramic slurry is 30-40%.

[0052] A lithium battery, wherein the raw materials for preparing the lithium battery include the ceramic diaphragm.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0054] The water-resistant soap-free emulsion with a high glass transition temperature of the present invention comprises a basic monomer, a high glass transition temperature monomer, a water-resistant monomer, an initiator, a neutralizer and water, wherein specific basic monomers, high glass transition temperature monomers and water-resistant monomers are used as monomer materials. The water-resistant soap-free emulsion with a high glass transition temperature provided by the present invention can be used as an adhesive for a ceramic diaphragm, and the prepared ceramic diaphragm has good heat resistance at 130°C and 150°C, and the peeling force after soaking in water is still strong, which can reach 82-100N / m, and the hardness is high. In the post-processing process, the ceramic diaphragm is coated with double-sided oily PVDF, and then immediately enters a water tank for extraction to remove the solvent, and the appearance is normal, the ceramic coating has a strong peeling force of 106-133N / m, and various performances are excellent, and the ceramic diaphragm has good water resistance. The binder prepared by the present invention is further used to prepare ceramic diaphragms and further used to prepare lithium batteries. The prepared lithium batteries have a high 700T capacity retention rate at 45°C, which is greater than 87.00% and can even reach 89.00%, while the thickness expansion rate is low, which is no higher than 9.87% and can even be as low as 9.27%, and the battery performance is excellent. DETAILED DESCRIPTION

[0055] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0056] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0057] Example 1

[0058] A water-resistant soap-free emulsion with a high glass transition temperature comprises the components shown in Table 1.

[0059] The method for preparing the above-mentioned water-resistant soap-free emulsion with high glass transition temperature comprises the following steps:

[0060] (1) Adding acrylic acid accounting for 5% of the total amount of acrylic acid, sodium hydroxide, and deionized water accounting for 40% of the total amount of deionized water into a reaction container, stirring and dissolving at a speed of 100 rpm, so that the hydrophilic monomer acrylic acid is neutralized under sodium hydroxide to serve as the base monomer for emulsion primer;

[0061] (2) adding butyl acrylate in an amount of 5% of the total amount of butyl acrylate, and introducing nitrogen to drive out oxygen for 1 hour;

[0062] (3) heating and maintaining a constant temperature of 80°C;

[0063] (4) then adding ammonium persulfate accounting for 50% of the total amount of ammonium persulfate added to initiate the reaction, and reacting for 0.5 hours;

[0064] (5) Gradually drop the remaining acrylic acid, the remaining butyl acrylate, acrylamide, tricyclohexane diacrylate, pentaerythritol tritetraacrylate, tert-butyl acrylate, dodecyl acrylate, octadecyl acrylate, and the remaining deionized water, and at the same time drop the remaining ammonium persulfate initiator, drop for 3 hours, and heat for 1 hour before stopping, to obtain a water-resistant soap-free emulsion with a high glass transition temperature, the copolymer content is 40%, and the product is in a blue emulsion state. The Tg of the final emulsion is 86° C., which has a high glass transition temperature.

[0065] Embodiment 2-5

[0066] The difference between Example 2-5 and Example 1 is that the components are different. The specific components and their contents are shown in Table 1.

[0067] Comparative Example 1 (emulsified formulation)

[0068] The composition of one emulsion is shown in Table 1.

[0069] The preparation method of the emulsion comprises the following steps:

[0070] Sodium dodecylbenzene sulfonate (SDBS) or sodium dodecyl sulfate (SDS) and dodecylphenol polyoxyethylene ether (OP-10) are used as emulsifiers, ammonium persulfate is used as initiator, the monomer composition is butyl acrylate: methyl methacrylate: methacrylic acid: acrylamide = 4:2:4:2, the copolymer content is 40%, and the product is in a white emulsion state.

[0071] Comparative Example 2 (aqueous solution type)

[0072] The composition of one emulsion is shown in Table 1.

[0073] The preparation method of the emulsion comprises the following steps:

[0074] Ammonium persulfate is used as the initiator, the monomer composition is methacrylic acid: butyl acrylate: acrylamide = 6:4:2, the copolymer content is 20%, and the product is a yellow transparent viscous liquid.

[0075] Table 1 Components and mass percentages (wt%) of the emulsions of the embodiments and comparative examples

[0076]

[0077]

[0078] Comparative Example 3

[0079] The difference between Comparative Example 3 and Example 1 is that the water-resistant monomer is replaced by an equal amount of deionized water.

[0080] Comparative Example 4

[0081] The difference between Comparative Example 4 and Example 1 is that the water-resistant monomer is replaced by octadecyl methacrylate.

[0082] Application Example 1-5 and Comparative Application Example 1-2

[0083] Application Examples 1-5 and Comparative Application Examples 1-2 are ceramic diaphragms prepared by using the emulsions of the above-mentioned Examples 1-5 and Comparative Examples 1-2 as binders. The preparation method of the ceramic diaphragm comprises the following steps:

[0084] The basic ceramic slurry formula is: 33 parts of ceramic powder, 4 parts of binder, 0.5 parts of carboxymethyl cellulose (CMC), 0.3 parts of wetting agent, and 0.2 parts of dispersant, which are configured into a ceramic slurry with a solid content of 35%. Then, a 5μm substrate is coated with a ceramic slurry coating with a thickness of about 2μm to obtain a diaphragm containing a ceramic coating (called a ceramic diaphragm) and test the basic properties of the ceramic diaphragm. The substrate selected above is a conventional breathable diaphragm, a 9μm porous PE diaphragm, with an air permeability of 180-200s.

[0085] Product effect testing

[0086] 1. Test methods

[0087] (1) Thickness

[0088] Sampling method: Cut a rectangular sample with a length of 1m and a width equal to the width of the small roll.

[0089] Test method: After flattening the sample, use a micrometer to randomly select points at the top, middle and bottom for measurement.

[0090] Data processing: record the actual thickness value of each point measured and calculate the arithmetic mean of the thickness at each point.

[0091] (2) Surface density:

[0092] Sampling method: Base film surface density: Cut a 100mm×100mm membrane sample. Finished product surface density: Cut a rectangular membrane sample, 100mm in length and the width is the width of the small roll.

[0093] Test method: Use an electronic balance with an accuracy of 0.001 part to weigh the sample mass m, measure the sample area S, and calculate its surface density according to formula (I).

[0094]

[0095] In formula (I), BW is the surface density, the unit is parts / m 2 ; m is the mass of one layer of sample, in units of parts; S is the area of ​​one layer of sample, in units of m 2 .

[0096] (3) Heat shrinkage:

[0097] Sampling method: Use a blade to cut a rectangular specimen. The width direction of the product (small roll width, ≤500mm) is used as the TD (Transverse Direction, i.e. perpendicular to the machine direction or transverse direction) length for the heat shrinkage test. 100mm is cut along the length direction of the product as the MD (Machine Direction, mechanical stretching direction or longitudinal direction) length for the heat shrinkage test.

[0098] Test method: Heat the electric thermostat to the specified temperature, measure the longitudinal and transverse dimensions of each sample, record and number them, and evenly place the samples flat in the paper jacket layer (a total of 5 layers). The samples should not be folded, wrinkled, or stuck. Heat the electric thermostat to the specified temperature, place the paper jacket with the product flat in the middle of the thermostat oven, start timing when the oven reaches the specified temperature, and take out the sample after the specified temperature is kept constant for a specified period of time. Cool to the test environment temperature and measure the longitudinal and transverse lengths. Calculate the thermal shrinkage rate according to formula (II). Record the thermal shrinkage rate of the sample and calculate the arithmetic mean of each sample.

[0099]

[0100] In formula (II), T is the thermal shrinkage rate of the sample, in %; L0 is the length of the sample before heating, in mm; L is the length of the sample after heating, in mm.

[0101] (4) Peel force:

[0102] Sampling method: Cut a rectangular sample with a width of 45mm and a length ≥120mm.

[0103] Test method: The sample is evenly and flatly attached to a steel plate with a width greater than 25mm and a length of 120mm with double-sided tape (the surface roughness of the steel plate is 50±25nm). The long side of the sample is pulled 3-8mm in the opposite direction parallel to the length direction of the test plate to completely separate the sample from the test plate in the width direction. Then the sample and the test plate are fixed on a peeling tester for testing. The preloading speed is 20mm / min, the test speed is 300mm / min, and the test is ended when the displacement is 40-50mm.

[0104] Data processing: record the average peel force value of the sample.

[0105] (5) Moisture content:

[0106] Sampling method: Use scissors to cut a rectangular sample of about 30mm in length and 20mm in width, put it into an electronic balance to weigh and record, the weighing range is 0.02-0.2 parts.

[0107] Test method: Set the heating furnace temperature to 150℃ and the end time to 500s on the main interface of the titration table. Check whether the water reagent is sufficient (100mL). It should be a light yellow transparent liquid in normal state. Check whether the sealing of the instrument is good. Check whether the electronic balance bubble meter is in the center and cleared normally.

[0108] Data processing: record the water content test value.

[0109] (6) Glass transition temperature: It can be tested by differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and dynamic thermomechanical analysis (DMA). It can also be calculated by the FOX equation during molecular design.

[0110] 2. Test results

[0111] (1) Basic properties of the ceramic diaphragms prepared in each application example and each comparative application example

[0112] Table 2 Basic properties of ceramic diaphragms prepared in various application examples and comparative application examples

[0113]

[0114] The ceramic diaphragm made of the adhesive of Examples 1-7 is thin, has good heat resistance at 130°C and 150°C, and its peeling force after soaking in water is still strong, reaching 82-100N / m. It has good water resistance, and both heat resistance and water resistance are better than the ceramic diaphragm made of the traditional emulsion polymerization adhesive of Comparative Example 1 and the ceramic diaphragm made of the aqueous solution polymerization adhesive of Comparative Example 2.

[0115] (2) The samples of the process were tested and the three-point hardness data of the core were obtained as follows:

[0116] Table 3 Three-point hardness data of each ceramic diaphragm

[0117]

[0118]

[0119] It can be seen from the above table that the water-based diaphragms prepared from the emulsions of Examples 1-7 of the present invention have significantly greater three-point hardness of the core, which can shape the core, reduce the incidence of defective products in the packaging process, and improve the one-time yield of the packaging process.

[0120] (3) Application performance of ceramic diaphragms in post-processing

[0121] The ceramic diaphragm is coated with double-sided oily PVDF, that is, a layer of PVDF dissolved in dimethylacetamide (DMAC) is coated on the ceramic coating, and then immediately put into a water tank for extraction to remove the solvent. This process takes about 30 minutes (50m / min).

[0122] Table 4 Application performance of various ceramic diaphragms in post-processing

[0123]

[0124] As can be seen from the above table, the ceramic diaphragms made with the adhesives of Examples 1-7 performed well in oil-based coating, had normal appearance, had strong ceramic coating peeling force of 106-133N / m, had excellent performance in various properties, and had good water resistance. However, the ceramic diaphragms made with the adhesives of Comparative Application Examples 1 and 2 had poor water resistance, and after coating with oil-based PVDF, ceramic powder in the water inlet tank fell off severely, and the ceramic coating peeling force was also significantly low.

[0125] (4) Performance of ceramic diaphragms in batteries

[0126] Table 5 Performance test results of batteries made of various ceramic diaphragms

[0127]

[0128]

[0129] As can be seen from the above table, the ceramic diaphragms made from the adhesives of Examples 1-7 have a high 700T capacity retention rate at 45°C, greater than 87.00%, and can even reach 89.00%, while the thickness expansion rate is low, not higher than 9.87%, and can even be as low as 9.27%. However, the capacity retention rate of the lithium battery made from the diaphragm of Comparative Application Example 1 is low, while the thickness expansion rate is very high, and the battery performance is poor. The capacity retention rate of the lithium battery made from the ceramic diaphragm of Comparative Application Example 2 is low.

Claims

1. A ceramic diaphragm adhesive, characterized in that: It comprises a water-resistant soap-free emulsion with a high glass transition temperature, wherein the water-resistant soap-free emulsion with a high glass transition temperature is composed of the following raw material components in terms of mass percentage: Basic monomer 10-30%, High glass transition temperature monomer 10-25%, Water-resistant monomer 1-8%, Initiator 0.01-3%, Neutralizer 0.01-5%, Water 50-70%; The base monomer includes at least one of methacrylic acid, acrylic acid, methyl methacrylate, butyl acrylate, isooctyl acrylate, glycidyl methacrylate, and itaconic acid; The high glass transition temperature monomer is acrylamide; The water-resistant monomer includes at least one of versatate vinyl carbonate, lauryl acrylate and octadecyl acrylate.

2. The adhesive for ceramic diaphragms according to claim 1, characterized in that According to mass percentage, it is composed of the following components: Basic monomer 10-20%, High glass transition temperature monomer 15-25%, Water-resistant monomer 5-8%, Initiator 0.01-2%, Neutralizer 3-5%, Water 50-60%.

3. The method for preparing the adhesive for ceramic diaphragms according to claim 1 or 2, characterized in that: The steps include: Firstly, a neutralizer, part of the basic monomer and part of the water are mixed, and a protective gas is introduced; then part of the initiator is added to initiate the reaction, and a high glass transition temperature monomer, a water-resistant monomer, the remaining basic monomer and the remaining water are added dropwise, and at the same time, the remaining initiator is added dropwise, and the reaction is carried out by heat preservation to obtain the water-resistant soap-free emulsion.

4. The preparation method according to claim 3, characterized in that: The steps include: First, a basic monomer accounting for 1-15% of the total mass of the basic monomer, a neutralizer and water accounting for 40% of the total mass of water are mixed, a protective gas is introduced, an initiator accounting for 40-60% of the total mass of the initiator is added to initiate a reaction, the remaining basic monomer, a high glass transition temperature monomer, a water-resistant monomer and the remaining water are added dropwise, and the remaining initiator is added dropwise at the same time, and the reaction is carried out by heat preservation to obtain the water-resistant soap-free emulsion.

5. A ceramic diaphragm, characterized in that: The ceramic diaphragm comprises a ceramic coating and a diaphragm substrate, and the raw material components for preparing the ceramic coating comprise the adhesive for the ceramic diaphragm according to claim 1 or 2, ceramic powder, carboxymethyl cellulose, a wetting agent, and a dispersant.

6. The ceramic diaphragm according to claim 5, characterized in that: The raw material components for preparing the ceramic coating include, by weight: 1-10 parts of adhesive for ceramic diaphragm, Ceramic powder 20-40 parts, Carboxymethyl cellulose 0.01-3 parts, Wetting agent 0.01-2 parts, Dispersant 0.01-2 parts.

7. The ceramic diaphragm according to claim 6, characterized in that: The raw material components for preparing the ceramic coating include, by weight: 1-10 parts of adhesive for ceramic diaphragm, 33-40 parts of ceramic powder, Carboxymethyl cellulose 0.5-2 parts, Wetting agent 0.3-1 part, Dispersant 0.2-1 part.

8. The method for preparing a ceramic diaphragm according to any one of claims 5 to 7, characterized in that: The steps include: The ceramic diaphragm adhesive, ceramic powder, carboxymethyl cellulose, a wetting agent, and a dispersant are mixed to form a ceramic slurry, which is then coated on a diaphragm substrate.

9. A lithium battery, characterized in that: The raw materials for preparing the lithium battery include the ceramic diaphragm according to any one of claims 5 to 7.

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