Preparation of low-static lithium battery slurry and diaphragm

Abstract

The invention relates to the technical field of battery diaphragms, and provides preparation of low-static lithium battery slurry and a diaphragm. The low-static lithium battery slurry is prepared from the following components in parts by weight: 10 to 15 parts of PVDF (Polyvinylidene Fluoride), 0.5 to 1.0 part of a dispersing agent, 9 to 15 parts of a thickening agent, 10 to 20 parts of a binding agent, 4 to 10 parts of dicalcium silicate, 0.2 to 0.5 part of an antistatic agent and 60 to 70 parts of water, the antistatic agent comprises an antistatic agent A and an antistatic agent B in a weight ratio of (4-9): 1; the antistatic agent A is prepared from the following raw materials in percentage by weight: 10%-15% of binary acid, 10%-15% of diamine, 0.05%-0.5% of a catalyst and the balance of polyether; the antistatic agent B comprises maleic acid-acrylic acid copolymer sodium salt. According to the technical scheme, the problem that the electrostatic value of the lithium battery diaphragm is relatively high in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery separators, and in particular to the preparation of a low-static lithium battery slurry and a separator. Background Art

[0002] In lithium-ion battery structures, the separator is a key internal component. Its performance determines the battery's interface structure and internal resistance, which in turn directly affects battery capacity, cycle life, safety, and other characteristics. Therefore, a high-performance separator is crucial to improving the overall performance of the battery.

[0003] Currently, the primary method for improving the performance of wet-process separators is to coat the surface of the base membrane with a layer of functional material. This method effectively enhances the separator's thermal stability, mechanical strength, and puncture resistance, thereby extending the battery's cycle life.

[0004] However, during the coating and slitting stages of production, the high-speed operation of the equipment generates static electricity on the separator. This static electricity is difficult to dissipate promptly, leading to accumulation and posing a threat to battery safety. Furthermore, static electricity on the separator surface can attract dust and other small foreign matter, reducing battery consistency. During the battery cell production process, static electricity can also cause separators to cling to each other, resulting in misalignment between the separator and the electrode, reducing the efficiency of the battery separator.

[0005] Based on the above problems, the development of low-static lithium battery slurry and the subsequent preparation of low-static diaphragms are of great practical significance for reducing static electricity accumulation in the production process and improving battery safety performance. Summary of the Invention

[0006] The present invention provides a preparation method for a low-static lithium battery slurry and a separator, which solves the problem of high static electricity value of lithium battery separators in related technologies.

[0007] The technical solutions of the present invention are as follows: The present invention provides a low-static lithium battery slurry, the raw materials of which include the following components in parts by weight: PVDF 10-15 parts, dispersant 0.5-1.0 parts, thickener 9-15 parts, binder 10-20 parts, dicalcium silicate 4-10 parts, antistatic agent 0.2-0.5 parts, water 60-70 parts; The antistatic agent comprises antistatic agent A and antistatic agent B in a weight ratio of 4 to 9:1; The raw materials of the antistatic agent A are composed of the following components in percentage by weight: 10%~15% dibasic acid, 10%~15% diamine, 0.05%~0.5% catalyst, and the balance is polyether; The antistatic agent B includes maleic acid-acrylic acid copolymer sodium salt.

[0008] As a further technical solution, the polyether includes one or both of polyethylene glycol and polypropylene oxide, preferably polyethylene glycol; The dibasic acid includes one or more of adipic acid, azelaic acid, and sebacic acid, preferably adipic acid; The diamine includes one or more of hexamethylenediamine, tetramethylenediamine, m-phenylenediamine, and p-phenylenediamine, preferably hexamethylenediamine; The catalyst includes one or both of a titanium catalyst and a zirconium catalyst.

[0009] In the present invention, the catalyst can accelerate the combination of the dibasic acid and the diamine, improve the reaction rate and reaction efficiency, so that the antistatic agent A is formed in a relatively short time, reducing energy consumption and production costs. The catalyst includes one or both of a titanium catalyst and a zirconium catalyst, wherein the titanium catalyst can be one or both of tetrabutyl titanate and diisopropyl bisoleate titanate, and the zirconium catalyst can be one or both of tetrabutyl zirconate and zirconyl acetate, preferably tetrabutyl titanate.

[0010] As a further technical solution, the preparation method of the antistatic agent A comprises the following steps: mixing the polyether, dibasic acid and diamine, adding the catalyst and mixing evenly to obtain the antistatic agent A.

[0011] As a further technical solution, when the mixing is uniform, the stirring speed is 20-25 r / min, for example, 20 r / min, 21 r / min, 22 r / min, 23 r / min, 24 r / min, 25 r / min, preferably 20 r / min, 25 r / min, more preferably 25 r / min; the temperature is 180-220 ° C, for example, 180 ° C, 185 ° C, 190 ° C, 195 ° C, 200 ° C, 205 ° C, 210 ° C, 215 ° C, 220 ° C, ℃, preferably 180℃, 200℃, 220℃, more preferably 200℃; pressure is -3mPa~-2mPa, for example, it can be -3mPa, -2.2mPa, -2.4mPa, -2.5mPa, -2.6mPa, -2.8mPa, -2mPa, preferably -3mPa, -2mPa, more preferably -2mPa; mixing time is 6~8h, for example, it can be 6h, 6.5h, 7h, 7.5h, 8h, preferably 6h, 7h, 8h, more preferably 7h.

[0012] In the present invention, an antistatic agent A with excellent performance can be prepared by rationally selecting polyether, dibasic acid, diamine, and catalyst, as well as optimizing the conditions during the preparation of antistatic agent A. This antistatic agent works synergistically with antistatic agent B to effectively improve the antistatic performance of low-static lithium battery slurry, thereby reducing the static value of lithium battery separators.

[0013] As a further technical solution, the dicalcium silicate is modified dicalcium silicate, and the raw materials of the modified dicalcium silicate include dicalcium silicate, water-soluble cobalt salt and polylactic acid.

[0014] As a further technical solution, the weight ratio of the water-soluble cobalt salt and polylactic acid to the dicalcium silicate is 2-5:32; The weight ratio of the water-soluble cobalt salt to the polylactic acid is 1-4:1.

[0015] In the present invention, the water-soluble cobalt salt is a conventional cobalt salt soluble in water, for example, it can be one or more of cobalt sulfate, cobalt chloride, cobalt nitrate, and cobalt acetate, preferably cobalt sulfate. The water-soluble cobalt salt and polylactic acid are used to modify the dicalcium silicate, which can improve the dispersion of the dicalcium silicate in the lithium battery slurry, make the dicalcium silicate less likely to agglomerate, and form a denser structure in the diaphragm, thereby ensuring that the diaphragm has a low static value and improving the puncture resistance of the diaphragm. By optimizing the water-soluble cobalt salt, the dicalcium silicate can be modified. The content ratio of the water-soluble cobalt salt, polylactic acid and dicalcium silicate is as follows: when the weight ratio of the water-soluble cobalt salt and polylactic acid to the dicalcium silicate is 2-5:32, for example, it can be 2:32, 3:32, 4:32, 5:32, preferably 3:32, 4:32, and the weight ratio of the water-soluble cobalt salt and polylactic acid is 1-4:1, for example, it can be 1:1, 2:1, 3:1, 4:1, preferably 1:1, 4:1, and more preferably 4:1, the puncture resistance of the diaphragm can be improved.

[0016] As a further technical solution, the preparation method of the modified dicalcium silicate comprises the following steps: A1, after mixing the dicalcium silicate and water, adding a water-soluble cobalt salt, adjusting the pH to 9-10, mixing uniformly, concentrating, and drying to obtain a dicalcium silicate premix; A2. Dispersing the polylactic acid in dichloromethane, adding the dicalcium silicate premix, mixing evenly, concentrating, and drying to obtain modified dicalcium silicate.

[0017] As a further technical solution, when adjusting the pH, an alkaline solution is used, and the alkaline solution includes one or more of ammonia water, sodium hydroxide solution, and potassium hydroxide solution.

[0018] As a further technical solution, the mass fraction of the alkaline solution is 20% to 25%, for example, it can be 20%, 21%, 22%, 23%, 24%, 25%, and preferably 22%.

[0019] As a further technical solution, in step A1, the mixing is carried out in a reactor at a temperature of 130-140° C. for 2-3 hours.

[0020] In the present invention, in step A1, the temperature is 130~140°C, for example, it can be 130°C, 132°C, 134°C, 135°C, 136°C, 138°C, 140°C, preferably 130°C, 140°C, more preferably 130°C; the stirring speed is 100~150r / min, for example, it can be 100r / min, 110r / min, 120r / min, 130r / min, 140r / min, 150r / min, preferably 100r / min, 150r / min, more preferably 100r / min.

[0021] As a further technical solution, in step A2, when the mixing is uniform, stirring is performed at a stirring speed of 200-300 r / min for 30-40 min.

[0022] In the present invention, in step A2, the temperature is 50~60°C, for example, it can be 50°C, 52°C, 55°C, 58°C, 60°C, preferably 50°C, 60°C, more preferably 50°C; the stirring speed is 200~300r / min, for example, it can be 200r / min, 220r / min, 240r / min, 260r / min, 280r / min, 300r / min, preferably 200r / min, 300r / min, more preferably 200r / min.

[0023] As a further technical solution, the dispersant includes one or more of polyacrylate ammonium salt, polyacrylate sodium salt, and polyvinyl alcohol, preferably polyacrylate ammonium salt; The thickener includes one or more of sodium hydroxymethyl cellulose, carboxymethyl hydroxypropyl cellulose, and hydroxyethyl cellulose, preferably sodium hydroxymethyl cellulose; The binder includes one or both of acrylonitrile polymer and sodium alginate.

[0024] In the present invention, the acrylonitrile polymer may be one or more of polyacrylonitrile and acrylonitrile-styrene-butadiene copolymer, preferably polyacrylonitrile.

[0025] The present invention provides a method for preparing a low-static lithium battery slurry, which is used to prepare the low-static lithium battery slurry, comprising the following steps: S1. Mixing the remaining components except the thickener, binder and antistatic agent to obtain a mixture; S2. Add the thickener, binder and antistatic agent to the mixture and mix them evenly to obtain the low-static lithium battery slurry.

[0026] As a further technical solution, in step S1, when the mixing is uniform, the rotation speed is 1800-2400 r / min, for example, 1800 r / min, 1900 r / min, 2000 r / min, 2100 r / min, 2200 r / min, 2300 r / min, 2400 r / min, the revolution speed is 30-60 r / min, for example, 30 r / min, 40 r / min, 50 r / min, 60 r / min, and the time is 60-80 min; In step S2, when the mixing is uniform, the rotation speed is 800~1100r / min, for example, it can be 800r / min, 900r / min, 1000r / min, 1100r / min, the revolution speed is 20~40r / min, for example, it can be 20r / min, 25r / min, 30r / min, 35r / min, 40r / min, and the time is 20~40min.

[0027] The present invention also provides a diaphragm, which is obtained by coating the low-static lithium battery slurry or the low-static lithium battery slurry prepared by the preparation method on one side or both sides of a base film and drying it.

[0028] As a further technical solution, the base film includes one or both of polyethylene base film and polypropylene base film, preferably polyethylene base film.

[0029] As a further technical solution, the drying is carried out by oven drying for 1 to 3 minutes at a temperature of 50 to 70°C.

[0030] As a further technical solution, the coating speed is 30-50 m / min.

[0031] As a further technical solution, a coating is formed after the coating, and the thickness of the coating is 2 to 5 μm, for example, 2 μm, 3 μm, 4 μm, 5 μm, preferably 2 μm, 4 μm, 5 μm, and more preferably 4 μm.

[0032] The working principle and beneficial effects of the present invention are: 1. In the present invention, the low-static lithium battery slurry includes PVDF, a dispersant, a thickener, a binder, dicalcium silicate, an antistatic agent and water. PVDF is polyvinylidene fluoride, which can bind the various components in the lithium battery slurry together to form a uniform and stable system. The addition of an additional binder can further enhance the bonding force between the components in the lithium battery slurry. With the combination of dispersants, thickeners, antistatic agents and other components, the prepared low-static lithium battery slurry has good bonding properties and low static properties, which can effectively improve the safety and consistency of the battery.

[0033] 2. In the present invention, an antistatic agent is introduced into the low-static lithium battery slurry. The antistatic agent includes antistatic agent A and sodium salt of maleic acid-acrylic acid copolymer. Antistatic agent A is composed of dibasic acid, diamine, catalyst and polyether, and has excellent conductivity, which can make the lithium battery slurry have basic conductivity. Under the joint action of sodium salt of maleic acid-acrylic acid copolymer and antistatic agent A, a synergistic effect is exerted to form a conductive film while also quickly conducting away electrostatic charges, thereby reducing the accumulation of static electricity during the diaphragm coating and slitting process, reducing the misalignment of the diaphragm and the electrode during the battery cell production process, and improving the safety performance of the battery. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0035] In the following examples and comparative examples, the model of PVDF is W8200; the model of ammonium polyacrylate is 1124; the model of dicalcium silicate is Darl-1, purchased from Hubei Darli Chemical Co., Ltd.; the viscosity of sodium hydroxymethyl cellulose is 1000 mPa·s; the model of polyacrylonitrile is HT-P68; the model of sodium maleic acid-acrylic acid copolymer is PMAS-90; the model of polyethylene glycol is PEG-600; and the material of the polyethylene base film is high-density polyethylene, model DMDA-8920.

[0036] Example 1 The raw materials of antistatic agent A are composed of the following components in percentage by weight: Adipic acid 10%, hexamethylenediamine 10%, tetrabutyl titanate 0.05%, the balance being polyethylene glycol; The preparation method of antistatic agent A comprises the following steps: polyethylene glycol, adipic acid and hexamethylenediamine are mixed and added into a synthesis reactor, tetrabutyl titanate is added, and the mixture is stirred at 20 r / min for 8 hours at 180° C. and -3 mPa to obtain antistatic agent A; A method for preparing a low-static lithium battery slurry comprises the following steps: S1, 10 parts of PVDF, 0.5 parts of ammonium polyacrylate, 4 parts of dicalcium silicate and 60 parts of water were mixed for 80 minutes in a planetary stirring device with a rotation speed of 1800 r / min and a revolution speed of 30 r / min to obtain a mixture; S2, adding 9 parts of sodium hydroxymethyl cellulose, 10 parts of polyacrylonitrile, 0.16 parts of antistatic agent A and 0.04 parts of sodium salt of maleic acid-acrylic acid copolymer to the mixture, and mixing for 40 minutes under a planetary stirring device with a rotation speed of 800 r / min and a revolution speed of 20 r / min to obtain a low-static lithium battery slurry; The low-static lithium battery slurry was coated on one side of a polyethylene film at a coating speed of 30 m / min, and dried at 50° C. for 3 min to obtain a separator with a thickness of 2 μm.

[0037] Example 2 The raw materials of antistatic agent A are composed of the following components in percentage by weight: Adipic acid 13%, hexamethylenediamine 13%, tetrabutyl titanate 0.25%, the balance being polyethylene glycol; The preparation method of antistatic agent A comprises the following steps: polyethylene glycol, adipic acid and hexamethylenediamine are mixed and added into a synthesis reactor, tetrabutyl titanate is added, and the mixture is stirred at 25 rpm for 7 hours at 200° C. and −2 mPa to obtain antistatic agent A; A method for preparing a low-static lithium battery slurry comprises the following steps: S1, 13 parts of PVDF, 0.8 parts of ammonium polyacrylate, 8 parts of dicalcium silicate and 65 parts of water were mixed for 70 minutes in a planetary stirring apparatus with a rotation speed of 2200 r / min and a revolution speed of 40 r / min to obtain a mixture; S2, adding 13 parts of sodium hydroxymethyl cellulose, 18 parts of polyacrylonitrile, 0.35 parts of antistatic agent A and 0.05 parts of sodium salt of maleic acid-acrylic acid copolymer to the mixture, and mixing for 30 minutes under a planetary stirring device with a rotation speed of 900 r / min and a revolution speed of 30 r / min to obtain a low-static lithium battery slurry; The low-static lithium battery slurry was coated on one side of a polyethylene film at a coating speed of 40 m / min, and dried at 60° C. for 1 min to obtain a separator with a thickness of 4 μm.

[0038] Example 3 The raw materials of antistatic agent A are composed of the following components in percentage by weight: Adipic acid 15%, hexamethylenediamine 15%, tetrabutyl titanate 0.5%, the balance being polyethylene glycol; The preparation method of antistatic agent A comprises the following steps: polyethylene glycol, adipic acid and hexamethylenediamine are mixed and added into a synthesis reactor, tetrabutyl titanate is added, and the mixture is stirred at 25 rpm for 6 hours at 220° C. and −2 mPa to obtain antistatic agent A; A method for preparing a low-static lithium battery slurry comprises the following steps: S1, 15 parts of PVDF, 1.0 part of ammonium polyacrylate, 10 parts of dicalcium silicate and 70 parts of water were mixed for 60 minutes in a planetary stirring device with a rotation speed of 2400 r / min and a revolution speed of 60 r / min to obtain a mixture; S2, adding 15 parts of sodium hydroxymethyl cellulose, 20 parts of polyacrylonitrile, 0.45 parts of antistatic agent A and 0.05 parts of sodium salt of maleic acid-acrylic acid copolymer to the mixture, and mixing for 20 minutes under a planetary stirring device with a rotation speed of 1100 r / min and a revolution speed of 40 r / min to obtain a low-static lithium battery slurry; The low-static lithium battery slurry was coated on one side of a polyethylene film at a coating speed of 50 m / min, and dried at 70° C. for 1 min to obtain a separator with a thickness of 5 μm.

[0039] Example 4 The only difference between this embodiment and embodiment 2 is that, in this embodiment, the amount of antistatic agent A added is 0.32 parts, and the amount of maleic acid-acrylic acid copolymer sodium salt added is 0.08 parts.

[0040] Example 5 The only difference between this embodiment and embodiment 2 is that, in this embodiment, the amount of antistatic agent A added is 0.36 parts, and the amount of maleic acid-acrylic acid copolymer sodium salt added is 0.04 parts.

[0041] Example 6 The only difference between this embodiment and embodiment 5 is that, in this embodiment, the dicalcium silicate is modified dicalcium silicate, and the preparation method of the modified dicalcium silicate comprises the following steps: A1. After mixing 32 parts of dicalcium silicate and 50 parts of water in a reactor, 1.6 parts of cobalt sulfate were added, and the pH was adjusted to 9 with 22% ammonia water. The mixture was mixed at 130° C. for 3 hours, cooled, concentrated, and dried to obtain a dicalcium silicate premix; A2. Disperse 0.4 parts of polylactic acid in 35 parts of dichloromethane, add the above-mentioned dicalcium silicate premix, stir at a stirring speed of 200 r / min for 40 minutes, mix well, concentrate, and dry to obtain modified dicalcium silicate; A method for preparing a low-static lithium battery slurry comprises the following steps: S1, 13 parts of PVDF, 0.8 parts of ammonium polyacrylate, 8 parts of modified dicalcium silicate and 65 parts of water were mixed for 70 minutes in a planetary stirring device with a rotation speed of 2200 r / min and a revolution speed of 40 r / min to obtain a mixture; S2, adding 13 parts of sodium hydroxymethyl cellulose, 18 parts of polyacrylonitrile, 0.36 parts of antistatic agent A and 0.04 parts of sodium salt of maleic acid-acrylic acid copolymer to the mixture, and mixing for 30 minutes under a planetary stirring device with a rotation speed of 900 r / min and a revolution speed of 30 r / min to obtain a low-static lithium battery slurry; The low-static lithium battery slurry was coated on one side of a polyethylene film at a coating speed of 40 m / min, and dried at 60° C. for 1 min to obtain a separator with a thickness of 4 μm.

[0042] Example 7 The only difference between this embodiment and embodiment 6 is that, during the preparation of the modified dicalcium silicate in this embodiment, 4 parts of cobalt sulfate and 1 part of polylactic acid are added.

[0043] Example 8 The only difference between this embodiment and embodiment 6 is that, during the preparation of the modified dicalcium silicate in this embodiment, 2.4 parts of cobalt sulfate and 0.6 parts of polylactic acid were added.

[0044] Example 9 The only difference between this embodiment and embodiment 6 is that, during the preparation of the modified dicalcium silicate in this embodiment, 3.2 parts of cobalt sulfate and 0.8 parts of polylactic acid were added.

[0045] Example 10 The only difference between this embodiment and embodiment 6 is that, in this embodiment, the preparation method of modified dicalcium silicate is different, comprising the following steps: A1. After mixing 32 parts of dicalcium silicate and 50 parts of water in a reactor, 1 part of cobalt sulfate was added, and the pH was adjusted to 10 with 22% ammonia water. The mixture was mixed at 140° C. for 2 h, cooled, concentrated, and dried to obtain a dicalcium silicate premix; A2. Disperse 1 part of polylactic acid in 35 parts of dichloromethane, add the above-mentioned dicalcium silicate premix, stir at a stirring speed of 300 r / min for 30 minutes, mix evenly, concentrate, and dry to obtain modified dicalcium silicate.

[0046] Example 11 The only difference between this embodiment and Example 6 is that in this embodiment, the preparation method of modified dicalcium silicate is different, comprising the following steps: 32 parts of dicalcium silicate and 50 parts of water are mixed in a reactor, 2 parts of cobalt sulfate are added, the pH is adjusted to 9 with 22% ammonia water by mass, the mixture is mixed at 130° C. for 3 hours, cooled, concentrated, and dried to obtain modified dicalcium silicate.

[0047] Example 12 The only difference between this embodiment and Example 6 is that in this embodiment, the preparation method of modified dicalcium silicate is different, comprising the following steps: dispersing 2 parts of polylactic acid in 35 parts of dichloromethane, adding 32 parts of dicalcium silicate, stirring at 50°C and 200 r / min for 40 minutes, mixing evenly, concentrating, and drying to obtain modified dicalcium silicate.

[0048] Comparative Example 1 The only difference between this comparative example and Example 1 is that in this comparative example, the antistatic agent A is replaced by an equal amount of maleic acid-acrylic acid copolymer sodium salt.

[0049] Comparative Example 2 The only difference between this comparative example and Example 1 is that in this comparative example, the sodium salt of maleic acid-acrylic acid copolymer is replaced by an equal amount of antistatic agent A.

[0050] Comparative Example 3 The only difference between this comparative example and Example 1 is that no antistatic agent is added in this comparative example.

[0051] Experimental Example 1 The diaphragms prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to the following performance tests: ① Static electricity value: Use an electrostatic tester (model SIMCO FAX-003) to test the static electricity value of the diaphragm; ②Surface resistance: Use an electrostatic resistance meter (model GM3110) to test the surface resistance of the diaphragm; The test results are shown in Table 1.

[0052] Table 1 Static electricity values and surface resistance test results of Examples 1 to 5 and Comparative Examples 1 to 3

[0053] Compared with Comparative Examples 1 to 3, after the diaphragm is prepared using the low-static lithium battery slurry of Examples 1 to 5, the static value and surface resistance of the diaphragm are significantly reduced, indicating that when the antistatic agent includes antistatic agent A and maleic acid-acrylic acid copolymer sodium salt, the two have a synergistic effect. By adjusting the weight ratio of antistatic agent A and maleic acid-acrylic acid copolymer sodium salt to 4 to 9:1, the static value and surface resistance of the diaphragm can be significantly reduced.

[0054] Experimental Example 2 The puncture strength test of the separators prepared in Examples 5 to 12 was performed according to the method in GB / T 36363-2018 "Polyolefin separators for lithium ion batteries", wherein the puncture rate was 110 mm / min. The test results are shown in Table 2.

[0055] Table 2 Puncture resistance test results of Examples 5 to 12

[0056] Compared with Example 5 and Examples 11-12, after the low-static lithium battery slurry of Examples 6-10 is used to prepare the diaphragm, the puncture strength of the diaphragm can reach above 17.4N, indicating that the modification of dicalcium silicate with water-soluble cobalt salt and polylactic acid can improve the puncture resistance of the diaphragm.

[0057] Experimental Example 3 The membranes prepared in Examples 1 to 3 were tested for air permeability and surface density, wherein: Air permeability: The air permeability of the separator was tested according to the method in GB / T 36363-2018 "Polyolefin separators for lithium-ion batteries". The separator sample size was 100 mm × 100 mm, and the test result was the average of three samples. The test results are shown in Table 3: Table 3 Test results of air permeability and surface density of Examples 1 to 3

[0058] The above are only 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 should be included in the scope of protection of the present invention.

Claims

1. A low static lithium battery slurry, characterized in that: The raw materials include the following components in parts by weight: PVDF 10-15 parts, dispersant 0.5-1.0 parts, thickener 9-15 parts, binder 10-20 parts, dicalcium silicate 4-10 parts, antistatic agent 0.2-0.5 parts, water 60-70 parts; The antistatic agent comprises antistatic agent A and antistatic agent B in a weight ratio of 4 to 9:1; The raw materials of the antistatic agent A are composed of the following components in percentage by weight: 10%~15% dibasic acid, 10%~15% diamine, 0.05%~0.5% catalyst, and the balance is polyether; The antistatic agent B includes maleic acid-acrylic acid copolymer sodium salt.

2. The low-static lithium battery slurry according to claim 1, characterized in that: The polyether includes one or two of polyethylene glycol and polypropylene oxide; The dibasic acid includes one or more of adipic acid, azelaic acid, and sebacic acid; The diamine includes one or more of hexamethylenediamine, tetramethylenediamine, m-phenylenediamine, and p-phenylenediamine; The catalyst includes one or both of a titanium catalyst and a zirconium catalyst.

3. The low-static lithium battery slurry according to claim 1, characterized in that: The preparation method of the antistatic agent A comprises the following steps: mixing the polyether, dibasic acid and diamine, adding the catalyst and mixing them uniformly to obtain the antistatic agent A.

4. The low-static lithium battery slurry according to claim 3, characterized in that: When the mixing is uniform, the stirring speed is 20-25 r / min, the temperature is 180-220° C., the pressure is -3 mPa--2 mPa, and the mixing time is 6-8 h.

5. The low-static lithium battery slurry according to claim 1, characterized in that: The dicalcium silicate is modified dicalcium silicate, and the raw materials of the modified dicalcium silicate include dicalcium silicate, water-soluble cobalt salt and polylactic acid.

6. The low-static lithium battery slurry according to claim 5, characterized in that: The weight ratio of the water-soluble cobalt salt and polylactic acid to the dicalcium silicate is 2 to 5:32; The weight ratio of the water-soluble cobalt salt to the polylactic acid is 1-4:

1.

7. The low-static lithium battery slurry according to claim 5, characterized in that: The preparation method of the modified dicalcium silicate comprises the following steps: A1, after mixing the dicalcium silicate and water, adding a water-soluble cobalt salt, adjusting the pH to 9-10, mixing uniformly, concentrating, and drying to obtain a dicalcium silicate premix; A2. Dispersing the polylactic acid in dichloromethane, adding the dicalcium silicate premix, mixing evenly, concentrating, and drying to obtain modified dicalcium silicate.

8. The low-static lithium battery slurry according to claim 1, characterized in that: The dispersant includes one or more of polyacrylate ammonium salt, polyacrylate sodium salt, and polyvinyl alcohol; The thickener includes one or more of sodium hydroxymethyl cellulose, carboxymethyl hydroxypropyl cellulose, and hydroxyethyl cellulose; The binder includes one or both of acrylonitrile polymer and sodium alginate.

9. A method for preparing a low-static lithium battery slurry, for preparing the low-static lithium battery slurry according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Mixing the remaining components except the thickener, binder and antistatic agent to obtain a mixture; S2. Add the thickener, binder and antistatic agent to the mixture and mix them evenly to obtain the low-static lithium battery slurry.

10. A separator, obtained by coating a single or double-sided substrate film with the low-static lithium battery slurry according to any one of claims 1 to 8 or the low-static lithium battery slurry prepared by the preparation method according to claim 9 and drying the coating.

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