Fluorine-free normal-temperature adhesive lithium battery diaphragm coating slurry as well as preparation method and application thereof

Abstract

The invention relates to the technical field of lithium battery diaphragms, and provides fluorine-free normal-temperature adhesive lithium battery diaphragm coating slurry as well as a preparation method and application thereof. The fluorine-free normal-temperature adhesive lithium battery diaphragm coating slurry is prepared from the following raw material components in parts by weight: 10 to 20 parts of modified porous ceramic, 0 to 0.5 part of cyclizing agent, 3 to 4 parts of PE (Poly Ethylene) particle balls, 1 to 3 parts of lithium carboxymethyl cellulose, 1 to 3 parts of polymethyl methacrylate, 1 to 3 parts of polyacrylamide and 100 parts of water, the modified porous ceramic is prepared from the following raw materials in parts by weight: 10 parts of porous ceramic, 1 part of polyether nitrile type cationic waterborne polyurethane, 2-4 parts of poly (ethyl acrylate) and 100 parts of water. According to the technical scheme, the problems of poor coating wettability and room-temperature adhesion of the lithium battery diaphragm in related technologies are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery separators, and specifically, to a fluorine-free room-temperature adhesive lithium battery separator coating slurry, its preparation method and application. Background Art

[0002] As a core component in the battery structure, the lithium battery separator not only ensures the integrity of the internal structure of the battery, but also optimizes the battery function. On the one hand, the separator needs to have good ionic conductivity to ensure that lithium ions can migrate smoothly between the positive and negative electrodes; on the other hand, the separator also needs to have sufficient porosity and air permeability so that the electrolyte can fully infiltrate and fill its microporous structure.

[0003] Due to the low surface energy of polyolefin materials, the wettability with the electrolyte is poor, which directly leads to the fact that the pores of the lithium battery separator cannot be fully filled with the electrolyte, causing a serious negative impact on the overall performance of the battery. In order to effectively improve the wettability of the lithium battery separator with the electrolyte, the most direct and effective strategy is to coat and modify the surface of the lithium battery separator to form a coating. However, at present, the improvement of the wettability of the separator coating is very limited, and the prepared separator coating has poor hot pressing and room-temperature adhesiveness with the battery electrode. In order to improve the wettability and adhesiveness of the separator coating, the common practice now is to increase the coating thickness. However, the increase in the coating thickness will make the battery core too thick at the battery end and cannot be continuously produced. Therefore, the development of a room-temperature adhesive lithium battery separator coating slurry is very necessary. Summary of the Invention

[0004] The present invention provides a fluorine-free room-temperature adhesive lithium battery separator coating slurry, its preparation method and application, which solve the problems of poor wettability and room-temperature adhesiveness of the lithium battery separator coating in the related art.

[0005] The technical solution of the present invention is as follows: The present invention provides a fluorine-free room-temperature adhesive lithium battery separator coating slurry, and the raw materials include the following components in parts by weight: 10-20 parts of modified porous ceramics, 0-0.5 part of a ring-forming agent, 3-4 parts of PE particle balls, 1-3 parts of lithium carboxymethyl cellulose, 1-3 parts of polymethyl methacrylate, 1-3 parts of polyacrylamide, and 100 parts of water; The raw materials of the modified porous ceramics include the following components in parts by weight: 10 parts of porous ceramics, 1 part of polyether nitrile-based cationic aqueous polyurethane, 2-4 parts of ethyl polyacrylate, and 100 parts of water.

[0006] As a further technical solution, the preparation method of the modified porous ceramics includes the following steps: mixing the porous ceramics, polyether nitrile-based cationic aqueous polyurethane and water evenly, adding ethyl polyacrylate, reacting, and drying to obtain the modified porous ceramics.

[0007] In the present invention, the preparation method of the modified porous ceramic has a simple process operation, does not require complex equipment, can achieve industrial production, and reduces the production cost and production difficulty.

[0008] As a further technical solution, during the reaction, the temperature is 60-65°C and the time is 25-30 min.

[0009] In the present invention, when preparing the modified porous ceramic, the reaction conditions are mild and do not require extreme conditions such as high temperature and high pressure. This not only saves energy but also reduces the damage to the structure of the porous ceramic matrix, which is beneficial to maintaining the original properties and structural integrity of the porous ceramic and improving the safety and stability of production.

[0010] As a further technical solution, the porous ceramic includes one of porous alumina and porous zirconia.

[0011] In the present invention, the porous ceramic has a rich pore structure, provides a large specific surface area, and is beneficial to the full reaction and adhesion of polyether nitrile-based cationic waterborne polyurethane and ethyl polyacrylate on its surface and in the pores. Preferably, it is porous alumina.

[0012] As a further technical solution, the median particle size of the porous ceramic is 0.3-0.5 μm; the specific surface area is 25-30 m 2 / g; by volume, the porosity is 35%-45%.

[0013] In the present invention, by optimizing the various parameters of the porous ceramic, the modification effect can be enhanced.

[0014] As a further technical solution, the ring-forming agent includes cyclohexane or polyethylene glycol.

[0015] In the present invention, the ring-forming agent is preferably cyclohexane or polyethylene glycol. Among them, cyclohexane has a high volatility and can quickly volatilize during the drying process of the coating to form a relatively uniform pore structure; polyethylene glycol can reduce the surface tension of the coating slurry, making the slurry easier to spread and infiltrate on the surface of the base film. The ring-forming agent is more preferably cyclohexane.

[0016] The present invention also provides a preparation method of the fluorine-free normal-temperature adhesive lithium battery separator coating slurry. When the slurry is applied by dot coating, it includes the following steps: S1: Mix the modified porous ceramic, the ring-forming agent and water, and perform the first emulsification to obtain a first substance; S2. Mix the first substance and PE particle balls, and perform the second emulsification to obtain a second substance; S3. Mix the second substance and lithium carboxymethyl cellulose, and perform the third emulsification to obtain a third substance; S4. Mix the third substance and polymethyl methacrylate, and perform the fourth emulsification to obtain the fourth substance; S5. Mix the fourth substance and polyacrylamide, and perform the fifth emulsification to obtain the slurry; or When the slurry is applied by roll coating, the following steps are included: S1: Mix the modified porous ceramic and water, and perform the first emulsification to obtain the first substance; S2. Mix the first substance and PE particle balls, and perform the second emulsification to obtain the second substance; S3. Mix the second substance and lithium carboxymethyl cellulose, and perform the third emulsification to obtain the third substance; S4. Mix the third substance and polymethyl methacrylate, and perform the fourth emulsification to obtain the fourth substance; S5. Mix the fourth substance and polyacrylamide, and perform the fifth emulsification to obtain the slurry.

[0017] As a further technical solution, when performing the first emulsification, the second emulsification, and the third emulsification, the emulsification conditions are each independently: temperature 50 - 60°C, vacuum degree -0.095 - -0.08 MPa, rotation speed 1000 - 2000 r / min, revolution speed 30 - 40 r / min, and time 30 - 40 min.

[0018] As a further technical solution, when performing the fourth emulsification and the fifth emulsification, the emulsification conditions are each independently: temperature 50 - 60°C, vacuum degree -0.095 - -0.08 MPa, rotation speed 1000 - 2000 r / min, revolution speed 30 - 40 r / min, and time 20 - 30 min.

[0019] The present invention also provides the application of the non - fluorine normal - temperature adhesiveness lithium battery separator coating slurry or the slurry obtained by the preparation method in a lithium battery separator.

[0020] As a further technical solution, the slurry is coated on at least one side of the base film by dot coating or roll coating.

[0021] As a further technical solution, during the coating, the coating amount is 0.4 - 0.6 g / m 2 .

[0022] The working principle and beneficial effects of the present invention are as follows: In the present invention, by optimizing the raw material composition of the slurry, the wettability and room - temperature adhesiveness of the lithium battery separator coating are significantly improved. Among them: (1) The modified porous ceramic can not only maintain the excellent liquid absorption and liquid retention ability of the porous ceramic, but also increase the contact area with the electrode sheet, thereby enhancing the adhesiveness; (2) The ring-forming agent can improve the interfacial properties between the slurry and the base film during the dot coating process, enabling the coating to adhere better to the surface of the base film and preventing subsequent peeling. Meanwhile, the pore structure generated during the drying process of the coating can provide more transmission channels for lithium ions, enhancing the performance of the lithium battery. (3) The compound use of PE particle balls and two non-fluorinated polymers, polymethyl methacrylate and polyacrylamide, not only endows the lithium battery separator with excellent room-temperature adhesion performance, enhances the stability of the overall structure, but also improves the safety of the lithium battery. (4) Lithium carboxymethyl cellulose can effectively promote the migration efficiency of ions inside the lithium battery by virtue of its excellent ion conduction characteristics, enhance the overall performance of the lithium battery, and extend its service life. Description of the Drawings

[0023] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0024] Figure 1 SEM image of the slurry in Example 1 of the present invention at 200 times magnification; Figure 2 SEM image of the slurry in Example 1 of the present invention at 1000 times magnification; Figure 3 SEM image of the slurry in Example 1 of the present invention at 15000 times magnification. Specific Embodiments

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0026] In the following embodiments and comparative examples, unless otherwise specified, the median particle size of the porous alumina is 0.4 μm, and the specific surface area is 28 m 2 / g, with a porosity of 40% by volume; the density of the polyether nitrile-based cationic aqueous polyurethane is 1.25 g / cm³ (25 °C), the number average molecular weight Mn is 8000 - 10000 g / mol; the number average molecular weight Mn of polyethyl acrylate is 100000 - 110000 g / mol, and the Tg is -20 °C to -15 °C; the number average molecular weight Mn of the PE particle spheres is 80000 - 90000 g / mol, the median particle size is 0.53 μm, and the Tg is 87 °C to 90 °C; the number average molecular weight Mn of polymethyl methacrylate is 200000 - 220000 g / mol, and the Tg is 100 °C to 103 °C; the number average molecular weight Mn of polyacrylamide is 300000 - 350000 g / mol, and the Tg is 170 °C to 175 °C; the median particle size of alumina is 0.4 μm.

[0027] Example 1 A method for preparing a non-fluorinated normal-temperature adhesiveness lithium battery separator coating slurry, comprising the following steps: S1: Mix 20 parts of modified porous alumina, 0.5 part of cyclohexane, and 100 parts of water, and stir at a self-rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa for the first emulsification for 40 min to obtain a first substance; S2. Mix the first substance and 4 parts of PE particle spheres, and stir at a self-rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa for the second emulsification for 40 min to obtain a second substance; S3. Mix the second substance and 3 parts of lithium carboxymethyl cellulose, and stir at a self-rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa for the third emulsification for 40 min to obtain a third substance; S4. Mix the third substance and 3 parts of polymethyl methacrylate, and stir at a self-rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.08 MPa for the fourth emulsification for 30 min to obtain a fourth substance; S5. Mix the fourth substance and 3 parts of polyacrylamide, and stir at a self-rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.08 MPa for the fifth emulsification for 30 min to obtain the slurry; Preparation method of modified porous alumina, comprising the following steps: adding 10 parts of porous alumina, 1 part of polyether nitrile type cationic waterborne polyurethane and 100 parts of water into a synthesis reactor, stirring evenly at 40 °C at a rotation speed of 30 r / min, and then pumping 2 parts of ethyl polyacrylate through a microreaction channel at a pump speed of 6 mL / min. After pumping into the synthesis reactor, reacting at 60 °C for 30 min, and drying to obtain the modified porous alumina; SEM images of the slurry at 200 times magnification, 1000 times magnification and 15000 times magnification are respectively as Figures 1 to 3 shown.

[0028] Example 2 Preparation method of a fluorine-free normal-temperature adhesive lithium battery separator coating slurry, comprising the following steps: S1: Mix 10 parts of modified porous ceramics, 0.2 part of cyclohexane and 100 parts of water, and stir at a rotation speed of 1000 r / min and a revolution speed of 30 r / min in a vacuum environment at 50 °C and a vacuum degree of -0.08 MPa for the first emulsification for 30 min to obtain a first substance; S2. Mix the first substance with 3 parts of PE particle balls, and stir at a rotation speed of 1000 r / min and a revolution speed of 30 r / min in a vacuum environment at 50 °C and a vacuum degree of -0.08 MPa for the second emulsification for 30 min to obtain a second substance; S3. Mix the second substance with 1 part of lithium carboxymethyl cellulose, and stir at a rotation speed of 1000 r / min and a revolution speed of 30 r / min in a vacuum environment at 50 °C and a vacuum degree of -0.08 MPa for the third emulsification for 30 min to obtain a third substance; S4. Mix the third substance with 1 part of polymethyl methacrylate, and stir at a rotation speed of 1000 r / min and a revolution speed of 30 r / min in a vacuum environment at 50 °C and a vacuum degree of -0.08 MPa for the fourth emulsification for 20 min to obtain a fourth substance; S5. Mix the fourth substance with 1 part of polyacrylamide, and stir at a rotation speed of 1000 r / min and a revolution speed of 30 r / min in a vacuum environment at 50 °C and a vacuum degree of -0.08 MPa for the fifth emulsification for 20 min to obtain the slurry; Preparation method of modified porous alumina, comprising the following steps: adding 10 parts of porous alumina, 1 part of polyether nitrile type cationic waterborne polyurethane and 100 parts of water into a synthesis reactor, stirring evenly at 40 °C at a rotation speed of 30 r / min, and then pumping 4 parts of ethyl polyacrylate through a microreaction channel at a pump speed of 6 mL / min. After pumping into the synthesis reactor, reacting at 65 °C for 25 min, and drying to obtain the modified porous alumina.

[0029] Example 3 A preparation method of a fluorine-free normal-temperature adhesive lithium battery separator coating slurry, comprising the following steps: S1: Mix 20 parts of modified porous alumina and 100 parts of water, and stir in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa at a rotation speed of 1200 r / min and a revolution speed of 40 r / min for the first emulsification for 40 min to obtain a first substance; S2. Mix the first substance and 4 parts of PE particle balls, and stir in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa at a rotation speed of 1200 r / min and a revolution speed of 40 r / min for the second emulsification for 40 min to obtain a second substance; S3. Mix the second substance and 3 parts of lithium carboxymethyl cellulose, and stir in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa at a rotation speed of 1200 r / min and a revolution speed of 40 r / min for the third emulsification for 40 min to obtain a third substance; S4. Mix the third substance and 3 parts of polymethyl methacrylate, and stir in a vacuum environment at 60 °C and a vacuum degree of -0.08 MPa at a rotation speed of 1200 r / min and a revolution speed of 40 r / min for the fourth emulsification for 30 min to obtain a fourth substance; S5. Mix the fourth substance and 3 parts of polyacrylamide, and stir in a vacuum environment at 60 °C and a vacuum degree of -0.08 MPa at a rotation speed of 1200 r / min and a revolution speed of 40 r / min for the fifth emulsification for 30 min to obtain the slurry; A preparation method of modified porous alumina, comprising the following steps: Add 10 parts of porous alumina, 1 part of polyether nitrile-type cationic waterborne polyurethane and 100 parts of water to a synthesis reaction kettle, stir evenly at 40 °C at a rotation speed of 30 r / min, and then pump 2 parts of ethyl polyacrylate into the synthesis reaction kettle through a micro reaction channel at a pump speed of 6 mL / min. After pumping into the synthesis reaction kettle, react at 60 °C for 30 min, and dry to obtain modified porous alumina.

[0030] Comparative Example 1 The difference between this comparative example and Example 1 is only that in this comparative example, the modified porous alumina is replaced with an equal amount of porous alumina.

[0031] Comparative Example 2 The difference between this comparative example and Example 1 is only that in this comparative example, the modified porous alumina is replaced with an equal amount of modified alumina; Preparation method of modified alumina, comprising the following steps: adding 10 parts of alumina, 1 part of polyether nitrile type cationic waterborne polyurethane and 100 parts of water into a synthesis reactor, stirring evenly at 40 °C at a rotation speed of 30 r / min, then pumping 2 parts of ethyl polyacrylate through a microreaction channel at a pump speed of 6 mL / min. After pumping into the synthesis reactor, reacting at 60 °C for 30 min, and drying to obtain the modified alumina.

[0032] Comparative Example 3 The difference between this comparative example and Example 1 is only that in this comparative example, the modified porous alumina is replaced with an equal amount of alumina.

[0033] Comparative Example 4 Preparation method of a fluorine-free normal-temperature adhesive lithium battery separator coating slurry, comprising the following steps: S1: Mix 20 parts of modified porous alumina and 100 parts of water, and stir at a rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa for the first emulsification for 40 min to obtain a first substance; S2. Mix the first substance and 4 parts of PE particle balls, and stir at a rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa for the second emulsification for 40 min to obtain a second substance; S3. Mix the second substance and 3 parts of lithium carboxymethyl cellulose, and stir at a rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa for the third emulsification for 40 min to obtain a third substance; S4. Mix the third substance and 3 parts of polymethyl methacrylate, and stir at a rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.08 MPa for the fourth emulsification for 30 min to obtain a fourth substance; S5. Mix the fourth substance and 3 parts of polyacrylamide, and stir at a rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.08 MPa for the fifth emulsification for 30 min to obtain the slurry; Preparation method of modified porous alumina, comprising the following steps: adding 10 parts of porous alumina, 1 part of polyether nitrile type cationic waterborne polyurethane and 100 parts of water into a synthesis reactor, stirring evenly at 40 °C at a rotation speed of 30 r / min, then pumping 2 parts of ethyl polyacrylate through a microreaction channel at a pump speed of 6 mL / min. After pumping into the synthesis reactor, reacting at 60 °C for 30 min, and drying to obtain the modified porous alumina.

[0034] Comparative Example 5 Preparation method of fluorine-free normal-temperature adhesiveness lithium battery separator coating slurry, comprising the following steps: S1: Mix 20 parts of modified porous alumina, 0.5 part of cyclohexane and 100 parts of water, and stir at a rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa for the first emulsification for 40 min to obtain a first substance; S2. Mix the first substance with 3 parts of lithium carboxymethyl cellulose, and stir at a rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa for the second emulsification for 40 min to obtain a second substance; S3. Mix the second substance with 3 parts of polymethyl methacrylate, and stir at a rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.08 MPa for the third emulsification for 30 min to obtain a third substance; S4. Mix the third substance with 3 parts of polyacrylamide, and stir at a rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.08 MPa for the fourth emulsification for 30 min to obtain the slurry; Preparation method of modified porous alumina, comprising the following steps: Add 10 parts of porous alumina, 1 part of polyether nitrile type cationic waterborne polyurethane and 100 parts of water into a synthesis reaction kettle, stir evenly at a rotation speed of 30 r / min at 40 °C, and then pump 2 parts of ethyl polyacrylate into the synthesis reaction kettle through a micro reaction channel at a pump speed of 6 mL / min. After pumping into the synthesis reaction kettle, react at 60 °C for 30 min, and dry to obtain modified porous alumina.

[0035] Comparative Example 6 The difference between this comparative example and Example 1 is only that in this comparative example, lithium carboxymethyl cellulose is replaced with an equal amount of sodium carboxymethyl cellulose.

[0036] Comparative Example 7 Preparation method of fluorine-free normal-temperature adhesiveness lithium battery separator coating slurry, comprising the following steps: S1: Mix 20 parts of modified porous alumina, 0.5 part of cyclohexane and 100 parts of water, and stir at a rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa for the first emulsification for 40 min to obtain a first substance; S2. Mix the first substance with 4 parts of PE particle balls, and stir at a self-rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa for 40 min for the second emulsification to obtain the second substance; S3. Mix the second substance with 3 parts of lithium carboxymethyl cellulose, and stir at a self-rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa for 40 min for the third emulsification to obtain the third substance; S4. Mix the third substance with 3 parts of polyacrylamide, and stir at a self-rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.08 MPa for 30 min for the fourth emulsification to obtain the slurry; The preparation method of the modified porous alumina includes the following steps: Add 10 parts of porous alumina, 1 part of polyether nitrile-based cationic waterborne polyurethane and 100 parts of water into a synthesis reactor, stir evenly at 40 °C at a rotation speed of 30 r / min, and then pump 2 parts of ethyl polyacrylate into it through a microreaction channel at a pump speed of 6 mL / min. After pumping into the synthesis reactor, react at 60 °C for 30 min and then dry to obtain the modified porous alumina.

[0037] Comparative Example 8 The preparation method of the slurry for the coating of the fluorine-free normal-temperature adhesive lithium battery separator includes the following steps: S1: Mix 20 parts of the modified porous alumina, 0.5 part of cyclohexane and 100 parts of water, and stir at a self-rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa for 40 min for the first emulsification to obtain the first substance; S2. Mix the first substance with 4 parts of PE particle balls, and stir at a self-rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa for 40 min for the second emulsification to obtain the second substance; S3. Mix the second substance with 3 parts of lithium carboxymethyl cellulose, and stir at a self-rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.095 MPa for 40 min for the third emulsification to obtain the third substance; S4. Mix the third substance with 3 parts of polymethyl methacrylate, and stir at a self-rotation speed of 1200 r / min and a revolution speed of 40 r / min in a vacuum environment at 60 °C and a vacuum degree of -0.08 MPa for 30 min for the fourth emulsification to obtain the slurry; Preparation method of modified porous alumina, comprising the following steps: adding 10 parts of porous alumina, 1 part of polyether nitrile type cationic waterborne polyurethane and 100 parts of water into a synthesis reactor, stirring evenly at 40 °C at a rotation speed of 30 r / min, and then pumping 2 parts of ethyl polyacrylate into the synthesis reactor through a microreaction channel at a pump speed of 6 mL / min. After pumping into the synthesis reactor, reacting at 60 °C for 30 min, and drying to obtain the modified porous alumina.

[0038] Pump the slurries prepared in Examples 1-2 and Comparative Examples 1-8 into a matrix dot coating structure, and use dot coating (dot spacing 680 μm, dot diameter 350 μm, coating amount 0.5 g / m 2 ) to coat the slurry on the wet polyvinyl film on one side (refer to the method in GB / T 36363-2018 to test the thickness of the base film as 7.1 μm and the air permeability value as 71 Sec / 100 mL), dry at 80 °C for 10 min to obtain a lithium battery separator, and conduct the following performance tests on the lithium battery separator: ① Thickness increment: Refer to GB / T 36363-2018 "Polyolefin Separators for Lithium Ion Batteries" to test the thickness of the battery separator, and calculate the thickness increment according to the formula: thickness increment = battery separator thickness - base film thickness; ② Liquid absorption rate and liquid retention rate: Cut the separator into samples with a size of 50 mm × 50 mm, and weigh the samples before the test and record it as m1; Process of testing the liquid absorption rate: Immerse the weighed separator in the electrolyte, take it out after soaking at 25 °C for 30 min, place it on industrial wiping paper, wipe the free electrolyte with industrial wiping paper, and then weigh and record it as m2; Process of testing the liquid retention rate: After weighing the sample for the liquid absorption rate, let it stand at 25 °C for 1 h and record it as m3; Liquid absorption rate (%) = (m2 - m1) / m1 × 100; Liquid retention rate (%) = (m3 - m1) / m1 × 100; The electrolyte is a mixture of an electrolyte and a solvent. The electrolyte in the electrolyte is lithium hexafluorophosphate, the solvent in the electrolyte is a mixture of ethylene carbonate and diethyl carbonate (the volume ratio of ethylene carbonate to diethyl carbonate is 1:1), and the concentration of the electrolyte in the electrolyte is 1 mol / L; Conduct the test 5 times and take the arithmetic mean as the final result; ③ Wettability: The calculation formula for wettability v is: v = h / t, where h is the wetting height (the height of the electrolyte penetrating in the vertical direction of the separator), the unit is mm, and t is the wetting time, the unit is min; The electrolyte is a mixture of an electrolyte and a solvent. The electrolyte in the electrolyte is lithium hexafluorophosphate, the solvent in the electrolyte is a mixture of ethylene carbonate and diethyl carbonate (the volume ratio of ethylene carbonate to diethyl carbonate is 1:1), and the concentration of the electrolyte in the electrolyte is 1 mol / L. Take the arithmetic mean of 5 tests as the final result. ④Ionic conductivity: Refer to GB / T 36363-2018 "Polyolefin Separators for Lithium-Ion Batteries" to test the ionic conductivity. The test temperature is 40 °C and the relative humidity is 48%. ⑤Adhesion of hot-pressed positive electrode sheet: Cut the separator to a size of 25 mm × 150 mm, and the positive electrode sheet (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) to a size of 25 mm × 150 mm; adjust the temperature of the hot press to 80 °C and the pressure to 1000 kg. Use the hot press to preheat the separator and the positive electrode sheet for 1 s and hot press for 1 s; use an electronic tensile testing machine to test the adhesion of the hot-pressed positive electrode sheet. Peel the separator and the positive electrode sheet until the tensile distance of the electronic tensile testing machine is 50 mm. The speed of the electronic tensile testing machine is 300 mm / min and the peeling angle is 180°. The adhesion of the hot-pressed positive electrode sheet = peeling force ÷ tensile distance of the electronic tensile testing machine. The peeling force is the arithmetic mean of the forces collected by the electronic tensile testing machine during the peeling of the separator and the positive electrode sheet, and is calculated based on the force data when the tensile distance is between 10 and 40 mm. ⑥Adhesion of hot-pressed negative electrode sheet: Cut the separator to a size of 25 mm × 150 mm, and the negative electrode sheet (carbon-based graphite electrode sheet with a carbon content of 91 wt%) to a size of 25 mm × 150 mm; adjust the temperature of the hot press to 80 °C and the pressure to 1000 kg. Use the hot press to preheat the separator and the negative electrode sheet for 1 s and hot press for 1 s; use an electronic tensile testing machine to test the adhesion of the hot-pressed negative electrode sheet. Peel the separator and the negative electrode sheet until the tensile distance of the electronic tensile testing machine is 50 mm. The speed of the electronic tensile testing machine is 300 mm / min and the peeling angle is 180°. The adhesion of the hot-pressed negative electrode sheet = peeling force ÷ tensile distance of the electronic tensile testing machine. The peeling force is the arithmetic mean of the forces collected by the electronic tensile testing machine during the peeling of the separator and the negative electrode sheet, and is calculated based on the force data when the tensile distance is between 10 and 40 mm. ⑦Adhesion of room-temperature positive electrode sheet: The difference from the test method of the adhesion of the hot-pressed positive electrode sheet is only that the temperature of the hot press is adjusted to 25 °C, the pressure is 1000 kg, and it is pressed for 60 s. ⑧Adhesion of room-temperature negative electrode sheet: The difference from the test method of the adhesion of the hot-pressed negative electrode sheet is only that the temperature of the hot press is adjusted to 25 °C, the pressure is 1000 kg, and it is pressed for 60 s.

[0039] The test results are shown in Table 1 below.

[0040] Table 1 Dot Coating Test Results

[0041] Comparisons between Example 1 and Comparative Examples 1-3 show that the wettability and room-temperature adhesiveness of the lithium battery separator coating can be significantly improved by modifying porous alumina. Comparisons between Example 1 and Comparative Example 4 show that the addition of a ring-forming agent during dot coating is beneficial to improving the comprehensive performance of the lithium battery separator. Comparisons between Example 1 and Comparative Example 5 show that the addition of PE particle balls is beneficial to improving the comprehensive performance of the lithium battery separator. Comparisons between Example 1 and Comparative Example 6 show that the addition of lithium carboxymethyl cellulose can improve the comprehensive performance of the lithium battery separator more than that of sodium carboxymethyl cellulose. Comparisons between Example 1 and Comparative Examples 7-8 show that the addition of two non-fluorinated polymers is beneficial to improving the comprehensive performance of the lithium battery separator.

[0042] Pump the slurry prepared in Example 3 into a gravure roll coating structure, and use roll coating (coating amount 0.5 g / m 2 ) to coat the slurry on one side of a wet-process polyethylene film (the thickness of the base film is 7.1 μm and the air permeability value is 71 Sec / 100 mL as tested by the method in GB / T 36363-2018), and dry it at 80 °C for 10 min to obtain a lithium battery separator, and perform performance tests on the lithium battery separator with reference to the above test methods. The test results are shown in Table 2 below.

[0043] Table 2 Roll Coating Test Results

[0044] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. Fluorine-free room temperature adhesive lithium battery separator coating slurry, characterized in that: The raw materials include the following components in parts by weight: 10-20 parts of modified porous ceramics, 0-0.5 parts of cyclizing agent, 3-4 parts of PE granular balls, 1-3 parts of lithium carboxymethyl cellulose, 1-3 parts of polymethyl methacrylate, 1-3 parts of polyacrylamide, and 100 parts of water; The raw materials of the modified porous ceramic include the following components in parts by weight: 10 parts of porous ceramic, 1 part of polyether nitrile type cationic waterborne polyurethane, 2-4 parts of polyethyl acrylate, and 100 parts of water.

2. The fluorine-free room temperature adhesive lithium battery separator coating slurry according to claim 1, characterized in that: The method for preparing the modified porous ceramic comprises the following steps: uniformly mixing the porous ceramic, polyether nitrile type cationic waterborne polyurethane and water, adding polyethyl acrylate, reacting, and drying to obtain the modified porous ceramic.

3. The fluorine-free room temperature adhesive lithium battery separator coating slurry according to claim 2, characterized in that: During the reaction, the temperature is 60-65° C. and the reaction time is 25-30 min.

4. The fluorine-free room temperature adhesive lithium battery separator coating slurry according to claim 1, characterized in that: The porous ceramic includes one of porous alumina and porous zirconia.

5. The fluorine-free room temperature adhesive lithium battery separator coating slurry according to claim 1, characterized in that: The median particle size of the porous ceramic is 0.3-0.5 μm; the specific surface area is 25-30 m 2 / g; by volume, the porosity is 35%~45%.

6. The fluorine-free room temperature adhesive lithium battery separator coating slurry according to claim 1, characterized in that: The cyclizing agent includes cyclohexane or polyethylene glycol.

7. The method for preparing the fluorine-free room-temperature adhesive lithium battery separator coating slurry according to any one of claims 1 to 6, characterized in that: When the slurry is applied in a dot coating manner, the following steps are included: S1: mixing the modified porous ceramic, the cyclizing agent and water, and emulsifying for the first time to obtain a first substance; S2, mixing the first substance and the PE granular balls, and emulsifying them for the second time to obtain a second substance; S3, mixing the second substance and lithium carboxymethyl cellulose, and emulsifying for the third time to obtain a third substance; S4, mixing the third substance and polymethyl methacrylate, and emulsifying for the fourth time to obtain a fourth substance; S5, mixing the fourth substance and polyacrylamide, and emulsifying for the fifth time to obtain the slurry; or When the slurry is applied by roller coating, the following steps are included: S1: mixing the modified porous ceramic and water, emulsifying for the first time, and obtaining a first substance; S2, mixing the first substance and the PE granular balls, and emulsifying them for the second time to obtain a second substance; S3, mixing the second substance and lithium carboxymethyl cellulose, and emulsifying for the third time to obtain a third substance; S4, mixing the third substance and polymethyl methacrylate, and emulsifying for the fourth time to obtain a fourth substance; S5, mixing the fourth substance and polyacrylamide, and emulsifying for the fifth time to obtain the slurry.

8. Use of the fluorine-free room-temperature adhesive lithium battery separator coating slurry according to any one of claims 1 to 6 or the slurry obtained by the preparation method according to claim 7 in lithium battery separators.

9. The use according to claim 8, characterized in that: The slurry is applied to at least one side of the base film by dot coating or roller coating.

10. The use according to claim 9, characterized in that: During the coating, the coating amount is 0.4~0.6g / m 2 .

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