Lithium ion battery slurry and coating process thereof

Abstract

The invention discloses lithium ion battery slurry and a coating process thereof, and belongs to the technical field of battery diaphragms. The lithium ion battery slurry comprises the following raw materials in parts by weight: 40-50 parts of ceramic powder, 10-15 parts of bio-based semi-aromatic polyamide, 10-15 parts of polyvinylidene fluoride, 35-45 parts of a solvent and 1-4 parts of a dispersing agent. The coating process comprises the following steps: A1, sequentially adding a solvent and a dispersing agent into a stirring tank, then adding ceramic powder, bio-based semi-aromatic polyamide and polyvinylidene fluoride, and uniformly stirring and mixing to obtain bio-based coating slurry; a2, feeding a polyethylene-based membrane into a coating device, coating by using the bio-based coating slurry prepared in the step A1, coating at least one side of a battery diaphragm by adopting a micro-concave roller coating mode, and drying and rolling the coated battery diaphragm to obtain a finished product of the ceramic-coated lithium battery composite diaphragm. The dispersing agent is used in the process of preparing the coating slurry, so that the mechanical property, the heat resistance and the adhesion property of the diaphragm can be improved.

Description

Technical Field

[0001] The present invention relates to the field of battery separators, and particularly to a lithium-ion battery slurry and its coating process. Background Art

[0002] Lithium-ion batteries have the characteristics of high energy density, high specific power, good cycle performance, no memory effect, and no pollution. They have good economic, social, and strategic significance and have become the most prominent green chemical power sources at present. With the development of lithium batteries, especially the increasing requirements for the energy density and capacity of power lithium-ion batteries, higher requirements are also put forward for the thermal stability of lithium-ion battery separators. At present, coating a coating on the base film is an important means to improve the thermal stability of lithium-ion battery separators.

[0003] Ceramic-coated separators are the most widely used lithium battery separators at present. This coating can effectively reduce the thermal shrinkage rate of lithium battery separators. However, ceramic particles and whiskers have a large specific surface area and are prone to agglomeration, and have poor adhesion to lithium battery electrodes. Moreover, ceramic separators have low mechanical strength and are prone to fracture and piercing, causing short circuits in lithium batteries. Patent CN116190913B provides a preparation method and device for a bio-based coating slurry. In this patent, PVDF (polyvinylidene fluoride) is first added to the mixed slurry of ceramic and solvent for dispersion, and then bio-based semi-aromatic polyamide is added for dispersion and mixing, and finally coated on the base film. The lithium battery separator produced by coating this slurry on the base film has high adhesion and strength. However, there are still defects in the poor compatibility between raw materials in this patent, which affects the overall performance of the separator. Summary of the Invention

[0004] The present invention provides a lithium-ion battery slurry and its coating process, which can solve the problem that the poor compatibility between raw materials in the background art affects the overall performance of the separator.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] In the first aspect, the present invention provides a lithium-ion battery slurry, comprising the following raw materials in parts by weight: 40-50 parts of ceramic powder, 10-15 parts of bio-based semi-aromatic polyamide, 10-15 parts of polyvinylidene fluoride, 35-45 parts of solvent, and 1-4 parts of dispersant; the dispersant is silane-modified polyurethane acrylate composite PDA@GO.

[0007] Further, the ceramic powder is one or more of alumina, silica, titanium dioxide, zirconium dioxide, magnesium oxide, zinc oxide, and barium oxide.

[0008] Further, the bio-based semi-aromatic polyamide is high molecular weight furyl aromatic polyamide.

[0009] Further, the solvent is N-methylpyrrolidone or N,N-dimethylacetamide.

[0010] Further, the preparation method of the dispersant is as follows:

[0011] A1: Add graphene oxide into Tris buffer solution, ultrasonicate for 4 - 5 h to obtain a GO suspension; add dopamine hydrochloride, stir for 20 - 30 min, then centrifuge, wash with deionized water 4 - 5 times, and freeze-dry for 12 - 24 h to obtain PDA@GO;

[0012] Among them, the dosage ratio of graphene oxide, Tris buffer solution, and dopamine hydrochloride is 0.3 - 0.5 g : 300 - 320 mL : 0.5 g; the Tris buffer solution is 10 mM and the pH value is 8.5.

[0013] In the above steps, dopamine hydrochloride self-polymerizes on the surface of graphene oxide to obtain PDA@GO. Graphene oxide has high heat resistance, which can improve the heat resistance of the separator. However, the dispersibility of graphene oxide is poor and it is easy to agglomerate, affecting the performance. In the present invention, polydopamine is coated on the surface of graphene oxide, which helps to improve the dispersibility of graphene oxide. Moreover, polydopamine itself has good heat resistance and adhesiveness, and it can improve the adhesiveness of the slurry while synergistically improving the heat resistance of the separator with graphene oxide.

[0014] A2: Dissolve isophorone diisocyanate, isocyanatopropyltriethoxysilane, and dibutyltin dilaurate in THF to obtain a mixed solution a; add the mixed solution a into a three-necked round-bottom flask, pre-pass nitrogen for 30 - 40 min, dissolve polytetramethylene ether glycol in THF to obtain a solution b; add the solution b dropwise into the mixed solution a, react at 80°C for 2 - 3 h, then continue to add 2-hydroxyethyl methacrylate, and continue to react at 80°C for 2 - 3 h. After the reaction is completed, purify with petroleum ether, sediment repeatedly 3 times, and then rotary evaporate the precipitate to obtain silane-modified polyurethane acrylate;

[0015] Among them, the dosage ratio of isophorone diisocyanate, isocyanatopropyltriethoxysilane, dibutyltin dilaurate, and THF in the mixed solution a is 2.80 g : 3.12 g : 0.09 g : 25 - 30 mL; the dosage ratio of polytetramethylene ether glycol and THF in the solution b is 24 g : 125 - 140 mL; the dosage ratio of the mixed solution a, the solution b, and 2-hydroxyethyl methacrylate is 25 mL : 125 - 140 mL : 1.98 g.

[0016] The above steps are carried out in two steps by solution polymerization. In the first step, polytetramethylene ether glycol reacts with isophorone diisocyanate and isocyanatopropyltriethoxysilane to obtain a prepolymer capped with -NCO and -Si(OEt)3. In the second step, the -NCO group reacts with the -OH of 2-hydroxyethyl methacrylate to obtain a silane-modified polyurethane acrylate capped with C=C double bond and -Si(OEt)3.

[0017] A3: Add the PDA@GO obtained in step A1 and the silane-modified polyurethane acrylate obtained in step A2 into an ethanol aqueous solution, react at 65 °C for 10 - 12 h, wash, and dry to obtain a dispersant.

[0018] Among them, the dosage ratio of PDA@GO, silane-modified polyurethane acrylate, and ethanol aqueous solution is 4 g : 0.4 - 0.6 g : 50 mL; the volume ratio of absolute ethanol to deionized water in the ethanol aqueous solution is (8 - 9) : 1.

[0019] In the above steps, the ethoxysilane in the silane-modified polyurethane acrylate will hydrolyze in the presence of water to generate silanol groups (Si-OH). The generated silanol groups (Si-OH) can undergo a condensation reaction with the hydroxyl groups (-OH) on the surface of PDA@GO to form siloxane bonds (Si-O-Si), thereby closely binding between PDA@GO and the silane-modified polyurethane acrylate, and obtaining a dispersant.

[0020] In the second aspect, the present invention provides a coating process for a lithium-ion battery slurry, including the following steps:

[0021] A1: Sequentially add a solvent and a dispersant into a stirring tank, then add ceramic powder, bio-based semi-aromatic polyamide, and polyvinylidene fluoride, and stir and mix evenly to obtain a bio-based coating slurry.

[0022] A2: Feed a polyethylene film into a coating device, use the bio-based coating slurry prepared in step A1 for coating, and coat it on at least one side of the battery separator by means of micro-embossing roll coating. The coated battery separator is dried and wound up to obtain a finished ceramic-coated lithium battery composite separator.

[0023] Further, the stirring speed in step A1 is 1500 - 2000 rpm / min, and the time is 1 - 2 h.

[0024] Advantages of the present invention:

[0025] In the process of preparing the coating slurry, the present invention uses a dispersant, which is a silane-modified polyurethane acrylate composite PDA@GO, and can improve the mechanical properties, heat resistance, and adhesion properties of the separator, specifically as follows:

[0026] (1) The long-chain structure of polyurethane acrylate can provide steric hindrance to prevent particles from approaching, improving the dispersibility of ceramic powder in the raw materials. The silane-modified polyurethane acrylate of the present invention contains chemical groups that are the same as or similar to those of bio-based semi-aromatic polyamide and polyvinylidene fluoride, which can enhance the compatibility with other matrices while improving the dispersibility of ceramic powder, and improve the mechanical properties of the separator.

[0027] (2) PDA@GO has high heat resistance and adhesion properties. When PDA@GO is combined with silane-modified polyurethane acrylate, it can be better dispersed in the raw materials, which is conducive to the exertion of the heat resistance and adhesion properties of this substance, improving the heat resistance and adhesion properties of the separator. Moreover, PDA@GO can adsorb on the surface of ceramic powder particles and other raw materials, further improving the dispersibility of the raw materials, thereby enhancing the mechanical properties of the separator. Specific Embodiments

[0028] The following describes the specific embodiments of the present invention in detail, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0029] Example 1

[0030] This example provides a lithium-ion battery slurry, which includes the following raw materials in parts by weight: 40 parts of silica ceramic powder, 10 parts of bio-based semi-aromatic polyamide, 10 parts of polyvinylidene fluoride, 35 parts of N-methylpyrrolidone, and 1 part of dispersant.

[0031] The coating process of the lithium-ion battery slurry is as follows:

[0032] A1: Add the solvent and dispersant to the stirring tank in sequence, then add the ceramic powder, bio-based semi-aromatic polyamide, and polyvinylidene fluoride, and stir at 1500 rpm / min for 1 h to mix evenly to obtain a bio-based coating slurry;

[0033] A2: Feed the polyethylene film into the coating device, and use the bio-based coating slurry prepared in step A1 for coating. Coating is carried out on at least one side of the battery separator by means of micro-gravure coating. The coated battery separator is dried and wound up to obtain a finished ceramic-coated lithium battery composite separator.

[0034] The preparation method of the dispersant is as follows:

[0035] A1: Add 0.3 g of graphene oxide to 300 mL (10 mM, pH value of 8.5) Tris buffer solution, ultrasonicate for 4 h to obtain a GO suspension; add 0.5 g of hydrochloric acid dopamine, stir for 20 min, then centrifuge, wash 4 times with deionized water, and freeze-dry for 12 h to obtain PDA@GO;

[0036] A2: Dissolve 2.80 g of isophorone diisocyanate, 3.12 g of isocyanatopropyltriethoxysilane, and 0.09 g of dibutyltin dilaurate in 25 mL of THF to obtain a mixed solution a; add the mixed solution a to a three-necked round-bottom flask, and pre-pass nitrogen for 30 min. Dissolve 24 g of polytetramethylene ether glycol in 140 mL of THF to obtain a solution b; add 140 mL of the solution b dropwise to 25 mL of the mixed solution a, react at 80 °C for 2 h, then continue to add 1.98 g of 2-hydroxyethyl methacrylate, and continue to react at 80 °C for 2 h. After the reaction is completed, purify with petroleum ether, sediment repeatedly 3 times, and then rotary evaporate the precipitate to obtain a silane-modified polyurethane acrylate;

[0037] A3: Add 4 g of the PDA@GO obtained in step A1 and 0.4 g of the silane-modified polyurethane acrylate obtained in step A2 to 50 mL of an ethanol aqueous solution (the volume ratio of absolute ethanol to deionized water is 9:1), and react at 65 °C for 10 h to obtain a dispersant.

[0038] Example 2

[0039] This example provides a lithium-ion battery slurry, which includes the following raw materials in parts by weight: 42 parts of silica ceramic powder, 11 parts of bio-based semi-aromatic polyamide, 11 parts of polyvinylidene fluoride, 38 parts of N-methylpyrrolidone, and 2 parts of dispersant.

[0040] The coating process of the lithium-ion battery slurry is as follows:

[0041] A1: Add the solvent and the dispersant to the stirring tank in sequence, then add the ceramic powder, bio-based semi-aromatic polyamide, and polyvinylidene fluoride, and stir at 2000 rpm for 2 h to mix evenly to obtain a bio-based coating slurry;

[0042] A2: Feed the polyethylene film into the coating device, use the bio-based coating slurry prepared in step A1 for coating, and coat it on at least one side of the battery separator by means of micro-embossing roll coating. The coated battery separator is dried and wound up to obtain a finished ceramic-coated lithium battery composite separator.

[0043] The preparation method of the dispersant is as follows:

[0044] A1: Add 0.4 g of graphene oxide to 310 mL (10 mM, pH value 8.5) of Tris buffer solution, ultrasonicate for 5 h to obtain a GO suspension; add 0.5 g of hydrochloric acid dopamine, stir for 25 min, then centrifuge, wash with deionized water 5 times, and freeze-dry for 24 h to obtain PDA@GO;

[0045] A2: Dissolve 2.80 g of isophorone diisocyanate, 3.12 g of isocyanatopropyltriethoxysilane, and 0.09 g of dibutyltin dilaurate in 25 mL of THF to obtain a mixed solution a; add the mixed solution a to a three-necked round-bottom flask, pre-pass nitrogen for 40 min, dissolve 24 g of polytetramethylene ether glycol in 135 mL of THF to obtain a solution b; add 135 mL of the solution b dropwise to 25 mL of the mixed solution a, react at 80 °C for 3 h, then continue to add 1.98 g of 2-hydroxyethyl methacrylate, and continue to react at 80 °C for 3 h. After the reaction, purify with petroleum ether, sediment repeatedly 3 times, and then rotary evaporate the precipitate to obtain silane-modified polyurethane acrylate;

[0046] A3: Add 4 g of PDA@GO obtained in step A1 and 0.5 g of the silane-modified polyurethane acrylate obtained in step A2 to 50 mL of an ethanol aqueous solution (the volume ratio of absolute ethanol to deionized water is 9:1), and react at 65 °C for 11 h to obtain a dispersant.

[0047] Example 3

[0048] This example provides a lithium-ion battery slurry, which includes the following raw materials in parts by weight: 45 parts of silica ceramic powder, 13 parts of bio-based semi-aromatic polyamide, 13 parts of polyvinylidene fluoride, 40 parts of N-methylpyrrolidone, and 2.5 parts of dispersant.

[0049] The coating process of the lithium-ion battery slurry is as follows:

[0050] A1: Add the solvent and the dispersant to the stirring tank in sequence, then add the ceramic powder, bio-based semi-aromatic polyamide, and polyvinylidene fluoride, and stir at 2000 rpm for 2 h to mix evenly to obtain a bio-based coating slurry;

[0051] A2: Feed the polyethylene film into the coating device, use the bio-based coating slurry prepared in step A1 for coating, and coat it on at least one side of the battery separator by means of micro-gravure coating. After coating, the battery separator is dried and wound up to obtain a finished ceramic-coated lithium battery composite separator.

[0052] The preparation method of the dispersant is as follows:

[0053] A1: Add 0.5 g of graphene oxide to 320 mL (10 mM, pH value 8.5) of Tris buffer solution, ultrasonicate for 5 h to obtain a GO suspension; add 0.5 g of hydrochloric acid dopamine, stir for 30 min, then centrifuge, wash with deionized water 5 times, and freeze-dry for 24 h to obtain PDA@GO;

[0054] A2: Dissolve 2.80 g of isophorone diisocyanate, 3.12 g of isocyanatopropyltriethoxysilane and 0.09 g of dibutyltin dilaurate in 30 mL of THF to obtain a mixed solution a; add the mixed solution a into a three-necked round-bottom flask, and pre-pass nitrogen for 40 min. Dissolve 24 g of polytetramethylene ether glycol in 125 mL of THF to obtain a solution b; slowly add 125 mL of the solution b dropwise into 25 mL of the mixed solution a, react at 80 °C for 3 h, then continue to add 1.98 g of 2-hydroxyethyl methacrylate, and continue to react at 80 °C for 3 h. After the reaction is completed, purify with petroleum ether, sediment repeatedly 3 times, and then rotary evaporate the precipitate to obtain a silane-modified polyurethane acrylate;

[0055] A3: Add 4 g of the PDA@GO obtained in step A1 and 0.6 g of the silane-modified polyurethane acrylate obtained in step A2 into 50 mL of an ethanol aqueous solution (the volume ratio of absolute ethanol to deionized water is 9:1), and react at 65 °C for 12 h to obtain a dispersant.

[0056] Example 4

[0057] The difference between this example and Example 3 is that:

[0058] A lithium-ion battery slurry includes the following raw materials in parts by weight: 47 parts of silica ceramic powder, 14 parts of bio-based semi-aromatic polyamide, 14 parts of polyvinylidene fluoride, 42 parts of N-methylpyrrolidone, and 3 parts of dispersant;

[0059] The remaining raw materials and steps are the same as those in Example 3.

[0060] Example 5

[0061] The difference between this example and Example 3 is that:

[0062] A lithium-ion battery slurry includes the following raw materials in parts by weight: 50 parts of silica ceramic powder, 15 parts of bio-based semi-aromatic polyamide, 15 parts of polyvinylidene fluoride, 45 parts of N-methylpyrrolidone, and 4 parts of dispersant;

[0063] The remaining raw materials and steps are the same as those in Example 3.

[0064] Comparative Example 1

[0065] The difference between this comparative example and Example 1 is that PDA is not added. The specific steps are as follows:

[0066] A1: Dissolve 2.80 g of isophorone diisocyanate, 3.12 g of isocyanatopropyltriethoxysilane, and 0.09 g of dibutyltin dilaurate in 25 mL of THF to obtain a mixed solution a; add the mixed solution a to a three-necked round-bottom flask, and pre-pass nitrogen for 30 min. Dissolve 24 g of polytetramethylene ether glycol in 140 mL of THF to obtain a solution b; slowly add 140 mL of the solution b dropwise to 25 mL of the mixed solution a, react at 80 °C for 2 h, then continue to add 1.98 g of 2-hydroxyethyl methacrylate, and continue to react at 80 °C for 2 h. After the reaction is completed, purify with petroleum ether, sediment repeatedly 3 times, and then rotary evaporate the precipitate to obtain silane-modified polyurethane acrylate;

[0067] A2: Add 4 g of GO and 0.4 g of the silane-modified polyurethane acrylate obtained in step A1 to 50 mL of an ethanol aqueous solution (the volume ratio of absolute ethanol to deionized water is 9:1), and react at 65 °C for 10 h to obtain a dispersant.

[0068] The remaining raw materials and steps are the same as those in Example 1.

[0069] Comparative Example 2

[0070] The difference between this comparative example and Example 1 is that the preparation method of the dispersant is as follows:

[0071] Add 4 g of GO and 0.4 g of polyurethane acrylate to 50 mL of an ethanol aqueous solution (the volume ratio of absolute ethanol to deionized water is 9:1), mechanically stir for 10 h and then dry to obtain a dispersant.

[0072] Comparative Example 3

[0073] The difference between this comparative example and Example 1 is that the dispersant is replaced with polyurethane acrylate, and the remaining raw materials and steps are the same as those in Example 1.

[0074] Comparative Example 4

[0075] The difference between this comparative example and Example 1 is that the dispersant is replaced with polyurethane, and the remaining raw materials and steps are the same as those in Example 1.

[0076] Comparative Example 5

[0077] The difference between this comparative example and Example 1 is that 1 part of the dispersant is replaced with 0.5 part of the dispersant, and the remaining raw materials and steps are the same as those in Example 1.

[0078] Comparative Example 6

[0079] The difference between this comparative example and Example 5 is that 4 parts of the dispersant are replaced with 4.5 parts of the dispersant, and the remaining raw materials and steps are the same as those in Example 5.

[0080] Performance tests were carried out on Examples 1 - 5 and Comparative Examples 1 - 6. According to GB / T 12027 - 2004, the thermal shrinkage rate of the separator baked at 200 °C for 1 h was tested; according to GBT 2792 - 2014, the adhesion strength performance of the separator was tested; the film was cut into a rectangle with a length of 15 cm and a width of 2.5 cm, and a tensile testing machine was used to input the corresponding parameters to obtain its tensile strength. The test results are shown in Table 1:

[0081] Table 1

[0082]

[0083]

[0084] As can be seen from Table 1, the heat resistance, adhesion and mechanical properties of the separators prepared in Examples 1 - 5 are all better than those in Comparative Examples 1 - 6.

[0085] In Comparative Example 1, PDA was not contained, and its thermal shrinkage rate, adhesion and mechanical properties all decreased, indicating that polydopamine itself has good heat resistance and adhesion. It can improve the heat resistance of the separator and the adhesion of the slurry while synergistically oxidizing graphene. And PDA@GO can adsorb on the surface of ceramic powder particles and other raw materials, further improving the dispersibility of the raw materials, thereby enhancing the mechanical properties of the separator.

[0086] In Comparative Example 2, the compatibility between GO and polyurethane acrylate is not as good as that in Comparative Example 1, so its comprehensive performance is worse than that in Comparative Example 1 and Example 1.

[0087] In Comparative Example 3, the dispersant is polyurethane acrylate, and in Comparative Example 4, the dispersant is polyurethane. The comprehensive performance of the separator is lower than that in Example 1.

[0088] The addition amounts of the dispersants in Comparative Examples 5 and 6 are lower than that in Example 1 and higher than that in Example 5 respectively. Their comprehensive performances are lower than those in Example 1 and Example 5, indicating that too much or too little addition amount of the dispersant will affect the comprehensive performance of the separator, and the addition amount in the present invention is the optimal amount.

[0089] The above discloses only several specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any changes that can be thought of by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A lithium-ion battery slurry, characterized in that, It includes the following raw materials in parts by weight: 40-50 parts of ceramic powder, 10-15 parts of bio-based semi-aromatic polyamide, 10-15 parts of polyvinylidene fluoride, 35-45 parts of solvent, and 1-4 parts of dispersant; the dispersant is silane-modified polyurethane acrylate composite PDA@GO.

2. The lithium-ion battery slurry according to claim 1, characterized in that, The ceramic powder is one or more of alumina, silica, titanium dioxide, zirconium dioxide, magnesium oxide, zinc oxide, and barium oxide.

3. A lithium-ion battery slurry according to claim 1, characterized in that, The bio-based semi-aromatic polyamide is high molecular weight furyl aromatic polyamide.

4. A lithium-ion battery slurry according to claim 1, characterized in that, The solvent is N-methylpyrrolidone or N,N-dimethylacetamide.

5. A lithium-ion battery slurry according to claim 1, characterized in that, The preparation method of the dispersant is as follows: A1: Add graphene oxide to Tris buffer solution, ultrasonicate for 4-5 h to obtain a GO suspension; add dopamine hydrochloride, stir for 20-30 min, then centrifuge, wash with deionized water 4-5 times, and freeze-dry for 12-24 h to obtain PDA@GO; A2: Dissolve isophorone diisocyanate, isocyanatopropyltriethoxysilane, and dibutyltin dilaurate in THF to obtain a mixed solution a; add the mixed solution a to a three-necked round-bottom flask, pre-pass nitrogen for 30-40 min, dissolve polytetramethylene ether glycol in THF to obtain a solution b; add the solution b dropwise to the mixed solution a, react at 80 °C for 2-3 h, then continue to add 2-hydroxyethyl methacrylate and react at 80 °C for another 2-3 h. After the reaction, purify with petroleum ether, sediment repeatedly 3 times, and then rotary evaporate the precipitate to obtain silane-modified polyurethane acrylate; A3: Add the PDA@GO obtained in step A1 and the silane-modified polyurethane acrylate obtained in step A2 to an ethanol aqueous solution, and react at 65 °C for 10-12 h to obtain the dispersant.

6. The lithium ion battery slurry according to claim 5, wherein, In step A1, the dosage ratio of graphene oxide, Tris buffer solution, and dopamine hydrochloride is 0.3-0.5 g: 300-320 mL: 0.5 g; the Tris buffer solution is 10 mM and the pH value is 8.

5.

7. A lithium-ion battery slurry according to claim 5, wherein In step A2, the dosage ratio of isophorone diisocyanate, isocyanatopropyltriethoxysilane, dibutyltin dilaurate, and THF in the mixed solution a is 2.80 g: 3.12 g: 0.09 g: 25-30 mL; the dosage ratio of polytetramethylene ether glycol and THF in the solution b is 24 g: 125-140 mL; the dosage ratio of the mixed solution a, the solution b, and 2-hydroxyethyl methacrylate is 25 mL: 125-140 mL: 1.98 g.

8. The lithium-ion battery slurry according to claim 5, wherein In step A3, the dosage ratio of PDA@GO, silane-modified polyurethane acrylate, and ethanol aqueous solution is 4 g: 0.4-0.6 g: 50 mL; the volume ratio of absolute ethanol and deionized water in the ethanol aqueous solution is (8-9):

1.

9. A coating process for the lithium-ion battery slurry according to any one of claims 1-8, characterized in that, It includes the following steps: A1: Add the solvent and the dispersant to a stirring tank in sequence, then add the ceramic powder, bio-based semi-aromatic polyamide, and polyvinylidene fluoride, and stir and mix evenly to obtain a bio-based coating slurry; A2: Feed the polyethylene film into the coating device, coat it with the bio-based coating slurry prepared in step A1, and coat it on at least one side of the battery separator by means of micro-embossing roll coating. After coating, the battery separator is dried and wound up to obtain the finished product of the ceramic-coated lithium battery composite separator.

10. A coating process for a lithium-ion battery slurry according to claim 9, characterized in that, The stirring speed in step A1 is 1500 - 2000 rpm / min, and the time is 1 - 2 h.

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