A high temperature resistant flame retardant composite current collector base film and preparation method thereof

Abstract

The present invention relates to the field of composite current collector production, and in particular to a high temperature resistant flame retardant composite current collector base film and a preparation method thereof. The composite current collector base film is calculated by weight and includes the following components: 100 parts of polyphenylene sulfide resin, 15-25 parts of carbon fiber, 10-30 parts of flame retardant, 2-4 parts of plasticizer, 0.6-2 parts of compatibilizer, 0.2-0.8 parts of coupling agent, 1-3 parts of lubricant, 0.3-1 parts of anti-blocking agent and 0.5-1.5 parts of antioxidant. The composite current collector base film prepared by the present invention not only has excellent high temperature resistance and flame retardancy, but also has relatively excellent performance in terms of mechanical strength and dimensional stability. In addition, the bonding force with the metal is also enhanced to a certain extent, making it more suitable for use in high-end lithium batteries or electrolyzer products.

Description

Technical Field

[0001] The present invention relates to the field of composite current collector production, and in particular to a high-temperature resistant and flame-retardant composite current collector base film and a preparation method thereof. Background Art

[0002] The current collector is an essential component of lithium-ion batteries. As a structure or component that collects current, its function is to collect the electrons generated by the electrochemical reaction and conduct them to an external circuit, thereby converting chemical energy into electrical energy. Common current collectors include metal foil and composite current collectors. Compared to traditional current collectors (aluminum foil or copper foil), composite current collectors can reduce metal usage, improve energy density and safety, and are expected to be widely used in secondary batteries.

[0003] The composite current collector has a multi-layer structure, with a polymer film as the substrate in the middle and metal layers on both sides of the substrate, wherein the substrate is generally PP, PET or PI. These substrates have very weak polarity, low surface tension, and poor affinity with metals, resulting in poor adhesion at the interface between them and the metal, and weak bonding with the metal. During the preparation of the current collector, the metal layer is easy to fall off, resulting in a low yield rate of the composite current collector. At the same time, their mechanical performance indicators are poor, and there is a risk of film breakage during the preparation process. In addition, other types of composite current collector base films on the market have more or less technical defects such as poor resistance to electrolyte corrosion, insufficient flame retardancy, poor high temperature resistance, and insufficient mechanical properties.

[0004] Therefore, there is a need in the art to develop a new type of composite current collector base film that is resistant to high temperature, corrosion, flame retardant and has excellent mechanical properties. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a high-temperature resistant and flame-retardant composite current collector base film and a preparation method thereof.

[0006] The purpose of the present invention is achieved by adopting the following technical solutions:

[0007] In a first aspect, the present invention provides a high-temperature resistant and flame-retardant composite current collector base film, which comprises the following components in parts by weight:

[0008] 100 parts of polyphenylene sulfide resin (PPS), 15-25 parts of carbon fiber, 10-30 parts of flame retardant, 2-4 parts of plasticizer, 0.6-2 parts of compatibilizer, 0.2-0.8 parts of coupling agent, 1-3 parts of lubricant, 0.3-1 parts of anti-blocking agent and 0.5-1.5 parts of antioxidant.

[0009] Preferably, the polyphenylene sulfide resin (PPS) is a linear high molecular weight polyphenylene sulfide resin (PPS) with a density of 1.34-1.36 g / cm3 , melt index 20-80g / 10min (330℃, 5kg).

[0010] Preferably, the carbon fiber is chopped carbon fiber with a length of 3-5 mm and a diameter of 5-8 μm.

[0011] Preferably, the flame retardant is a product obtained by subjecting 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine to chlorination treatment and then subjecting it to amidation reaction with 3-aminobenzotrifluoride.

[0012] Preferably, the plasticizer is one or a combination of epoxidized soybean oil (ESO), triethyl citrate (TEC), tributyl citrate (TBC), and trioctyl citrate (TOC), and more preferably epoxidized soybean oil (ESO).

[0013] Preferably, the compatibilizer is polypropylene grafted with glycidyl methacrylate (PP-g-GMA) or polypropylene grafted with maleic anhydride (PP-g-MAH). More preferably, it is polypropylene grafted with glycidyl methacrylate (PP-g-GMA), with a grafting rate of 0.8% and a melt index of 120 g / 10 min (190°C, 2.16 kg).

[0014] Preferably, the coupling agent is one or a combination of KH-550, KH-560, and KH-570.

[0015] Preferably, the lubricant is one or a combination of calcium stearate, magnesium stearate, zinc stearate, and barium stearate.

[0016] Preferably, the anti-adhesion agent is nano-scale silicon dioxide, and the particle size is preferably 20-50 nm.

[0017] Preferably, the antioxidant is a mixture of a main antioxidant 1010 and an auxiliary antioxidant 168 in a mass ratio of 1-3:1.

[0018] Preferably, the preparation method of the flame retardant comprises:

[0019] S1. Weigh 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine and add it to thionyl chloride. Stir thoroughly under a nitrogen atmosphere and an ice-water bath. Then gradually raise the temperature to 78-86°C and reflux with stirring for 12-24 hours. After the reaction is completed, remove the thionyl chloride and dry the mixture to obtain an intermediate product.

[0020] S2. Weigh the intermediate product and add it to tetrahydrofuran, add a basic catalyst, stir evenly under a nitrogen atmosphere and an ice-water bath, then add 3-aminotrifluorotoluene dropwise. After the addition is complete, continue stirring in the ice-water bath for at least half an hour, then gradually warm to room temperature, stir at room temperature for 20-30 hours, and after the reaction is completed, purify to obtain a flame retardant.

[0021] Preferably, in S1, the mass volume ratio of 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine and thionyl chloride is (0.22-0.66) g:(2-10) mL.

[0022] Preferably, in S2, the mass volume ratio of the intermediate product, 3-aminotrifluorotoluene and tetrahydrofuran is 1 g: (1.2-1.6) g: (20-40) mL.

[0023] Preferably, in S2, the alkaline catalyst is pyridine, and the amount of pyridine added is 4.2-6.5 times the mass of the intermediate product.

[0024] Preferably, in S2, the purification is performed by silica gel column chromatography, and the eluent used is a mixture of ethyl acetate and petroleum ether in a volume ratio of 1:2.

[0025] In a second aspect, the present invention provides a method for preparing a high-temperature resistant flame-retardant composite current collector base film, comprising the following steps:

[0026] Step 1: weigh PPS resin and dry it in vacuum at 120° C. for 4 hours; and treat the carbon fiber surface with a coupling agent before use;

[0027] Step 2: Add the dried PPS resin, flame retardant and compatibilizer into a high-speed mixer, stir and mix at a speed of 600-1000 rpm for 3-6 minutes, then add the plasticizer and lubricant, continue to stir and mix for 2-3 minutes, then add the anti-blocking agent and antioxidant, continue to stir and mix for 4-5 minutes, and finally add the carbon fiber treated with the coupling agent, stir and mix at a speed of 400-600 rpm for 1-3 minutes to obtain a mixture;

[0028] Step 3: introducing the mixed material into a twin-screw extruder with a length-to-diameter ratio of L / D=40:1, and melt-extruding in a temperature range of 290-320°C (zone I 290°C, zone II 310°C, zone III 320°C, and die head 305°C) to obtain a mixed melt;

[0029] Step 4: The mixed melt was cast through a T-die (die lip gap 0.8 mm) onto a cooling roller (25°C) to form a 200 μm thick casting sheet;

[0030] Step 5: preheating the cast sheet and then longitudinally stretching it, wherein the preheating temperature is 100-120°C, the time is 30s, the stretching temperature is 95-115°C, and the stretching ratio is 3.2 times;

[0031] Step 6: preheating the cast sheet and then transversely stretching it, wherein the preheating temperature is 100-110°C, the time is 30s, the stretching temperature is 110-125°C, and the stretching ratio is 3.5 times;

[0032] Step 7: heat-set the stretched cast sheet at 210-250°C for 10s, and perform corona treatment with the following parameters: power 8kW, speed 5m / min. After corona treatment, the sheet is cut and rolled up with the cutting tension controlled at 20N to obtain a high-temperature resistant and flame-retardant composite current collector base film.

[0033] The beneficial effects of the present invention are:

[0034] 1. This invention prepares a composite current collector base film. The base resin material is a high-strength, high-stability polyphenylene sulfide resin (PPS), with carbon fibers as a filler and reinforcement, and a fluorinated triazine derivative as a flame retardant. Furthermore, auxiliary materials such as plasticizers, compatibilizers, and coupling agents are added. The composite current collector base film prepared by this invention not only exhibits excellent high-temperature resistance and flame retardancy, but also exhibits superior mechanical strength and dimensional stability. Furthermore, its bonding strength with metals is enhanced, making it more suitable for use in high-end lithium batteries or electrolyzers.

[0035] 2. The filler used in the present invention is carbon fiber. After being treated with a silane coupling agent, the surface properties are enhanced, the compatibility with the resin material is better, a three-dimensional network skeleton is formed, and the thermal expansion coefficient is reduced.

[0036] 3. The flame retardant of this invention is a fluorinated triazine derivative synthesized by amidation of triazine acid chloride and 3-aminobenzotrifluoride. Its rigid triazine core, trifluoromethyl groups, and amide bonds provide it with exceptional flame retardancy. The triazine structure in the flame retardant promotes char formation, releasing CF3 upon heating. This dual-action gas-phase and condensed-phase flame retardancy significantly enhances the flame retardant effect.

[0037] 4. The composite current collector base film of the present invention has the synergistic effect of "PPS heat-resistant skeleton + carbon fiber reinforcement + fluorinated triazine flame retardant", which has high safety (flame retardant grade V-0), high stability (heat shrinkage <0.3%), lightweight (density <1.5g / cm 3 )’s core advantages, especially suitable for the high-end high-energy density battery needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention is further described with reference to the accompanying drawings. However, the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative effort.

[0039] Figure 1 These are SEM images of the front and back surfaces of the high-temperature resistant flame-retardant composite current collector base film prepared in Example 1 of the present invention, wherein (a) and (b) are the front surfaces, and (c) and (d) are the back surfaces;

[0040] Figure 2 1 is an SEM image of a cross section of a high-temperature resistant flame-retardant composite current collector base film prepared in Example 1 of the present invention, wherein (a) and (b) are cross-sectional views of different thicknesses;

[0041] Figure 3 This is an FTIR-ATR graph of the high-temperature resistant flame-retardant composite current collector base film prepared in Example 1 of the present invention;

[0042] Figure 4 This is the XPS graph (395-405 eV) of the high-temperature resistant flame-retardant composite current collector base film prepared in Example 1 of the present invention;

[0043] Figure 5 This is the XPS graph (280-295 eV) of the high-temperature resistant flame-retardant composite current collector base film prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the presence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments in their relative relationships, without substantially changing the technical content, should also be regarded as the scope of the present invention.

[0045] In order to better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0046] The present invention will be further described below with reference to the following examples.

[0047] Example 1:

[0048] A high-temperature resistant and flame-retardant composite current collector base film, comprising the following components in parts by weight:

[0049] 100 parts of polyphenylene sulfide resin (PPS), 20 parts of carbon fiber, 22 parts of flame retardant, 3 parts of plasticizer, 1.2 parts of compatibilizer, 0.6 parts of coupling agent, 2 parts of lubricant, 0.7 parts of anti-blocking agent and 1 part of antioxidant.

[0050] Among them, polyphenylene sulfide resin (PPS) is a linear high molecular weight polyphenylene sulfide resin (PPS) with a density of 1.35g / cm 3 , melt index 60g / 10min (330℃, 5kg).

[0051] Among them, the carbon fiber is chopped carbon fiber with a length of 3-5 mm and a diameter of 5-8 μm; the plasticizer is epoxidized soybean oil (ESO).

[0052] Among them, the compatibilizer is polypropylene grafted glycidyl methacrylate (PP-g-GMA), the grafting rate is 0.8%, and the melt index is 120g / 10min (190℃, 2.16kg).

[0053] The coupling agent is KH-550; the lubricant is calcium stearate; the anti-adhesion agent is nano-scale silicon dioxide with a particle size of 20-50 nm; and the antioxidant is a mixture of main antioxidant 1010 and auxiliary antioxidant 168 in a mass ratio of 2:1.

[0054] The preparation method of the flame retardant includes:

[0055] S1, chlorination treatment:

[0056] Weigh 0.44 g of 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (TCT-COOH) and add it to 8 mL of thionyl chloride. Stir thoroughly under a nitrogen atmosphere and an ice-water bath. Then gradually raise the temperature to 83°C and reflux with stirring for 18 hours. After the reaction is complete, remove the excess thionyl chloride by rotary evaporation and dry in vacuo to obtain the intermediate product (TCT-COCl).

[0057] S2. Amidation reaction:

[0058] 1 g of the intermediate product (TCT-COCl) was weighed and added to 30 mL of tetrahydrofuran (solvent), 5.3 g of pyridine was added as a catalyst, and the mixture was stirred evenly under a nitrogen atmosphere and an ice-water bath. Then, 1.4 g of 3-aminotrifluorotoluene was added dropwise. After the addition was completed, stirring was continued in the ice-water bath for at least half an hour, and then the temperature was gradually raised to room temperature. Stirring was carried out at room temperature for 25 hours. After the reaction was completed, the mixture was poured into ice water with a volume twice that of the reaction solution, the solid was collected by filtration, and washed three times with ice water. After drying, it was purified by silica gel column chromatography (eluent volume ratio: ethyl acetate / petroleum ether = 1:2), and the product was dried to obtain a flame retardant.

[0059] The method for preparing the high temperature resistant flame retardant composite current collector base film comprises the following steps:

[0060] Step 1: weigh PPS resin and dry it in vacuum at 120° C. for 4 hours; and treat the carbon fiber surface with a coupling agent before use;

[0061] Step 2: Add the dried PPS resin, flame retardant and compatibilizer into a high-speed mixer, stir and mix at a speed of 800 rpm for 4 minutes, then add the plasticizer and lubricant, continue to stir and mix for 3 minutes, then add the anti-blocking agent and antioxidant, continue to stir and mix for 5 minutes, and finally add the carbon fiber treated with the coupling agent, stir and mix at a speed of 500 rpm for 2 minutes to obtain a mixture;

[0062] Step 3: introducing the mixed material into a twin-screw extruder with a length-to-diameter ratio of L / D=40:1, and melt-extruding in a temperature range of 290-320°C (zone I 290°C, zone II 310°C, zone III 320°C, and die head 305°C) to obtain a mixed melt;

[0063] Step 4: The mixed melt was cast through a T-die (die lip gap 0.8 mm) onto a cooling roller (25°C) to form a 200 μm thick casting sheet;

[0064] Step 5: After preheating the cast sheet, longitudinally stretch it, wherein the preheating temperature is 110° C., the time is 30 seconds, the stretching temperature is 105° C., and the stretching ratio is 3.2 times;

[0065] Step 6: preheating the cast sheet and then transversely stretching it, wherein the preheating temperature is 110°C, the time is 30s, the stretching temperature is 120°C, and the stretching ratio is 3.5 times;

[0066] Step 7: heat-set the stretched cast sheet at 230°C for 10s, and perform corona treatment with the following parameters: power 8kW, speed 5m / min. After corona treatment, the sheet is cut and rolled up with the cutting tension controlled at 20N to obtain a high-temperature resistant and flame-retardant composite current collector base film.

[0067] The present invention performs corresponding tests on the composite current collector base film prepared in Example 1.

[0068] in, Figure 1 and Figure 2 This is a SEM schematic diagram of the composite current collector base membrane. It can be seen that there are a small amount of small particles on both the front and back sides of the composite current collector base membrane, which may be traces of carbon fiber, flame retardant or other additives.

[0069] Figure 3 This is the FTIR-ATR graph of the composite current collector base film. It can be seen from the figure that there are obvious double peaks of amide bonds (C=O and NH) and trifluoromethyl characteristic peaks (-CF3), indicating that the carboxyl group is successfully condensed with the amino group after chlorination, and also confirms the synthesis of the target product flame retardant.

[0070] at the same time, Figure 4 and Figure 5 They are the XPS images of the composite current collector base film in different scanning ranges, Figure 4 (range: 395-405 eV) can indicate that the membrane contains characteristic groups of amide -CONH; Figure 5 (Range: 280-295eV) can illustrate the presence of characteristic groups of O=CO and CO bonds in the film.

[0071] Example 2:

[0072] A high-temperature resistant and flame-retardant composite current collector base film is different from Example 1 only in that the preparation method of the flame retardant is different.

[0073] The preparation method of the flame retardant includes:

[0074] S1, chlorination treatment:

[0075] Weigh 0.22 g of 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (TCT-COOH) and add it to 2 mL of thionyl chloride. Stir thoroughly under a nitrogen atmosphere and an ice-water bath. Then gradually raise the temperature to 78°C and reflux with stirring for 24 hours. After the reaction is complete, remove the excess thionyl chloride by rotary evaporation and dry in vacuo to obtain the intermediate product (TCT-COCl).

[0076] S2. Amidation reaction:

[0077] 1 g of the intermediate product (TCT-COCl) was weighed and added to 20 mL of tetrahydrofuran (solvent). Pyridine was added as a catalyst in an amount of 4.2 times the mass of the intermediate product. The mixture was stirred evenly under a nitrogen atmosphere and an ice-water bath. Then, 1.2 g of 3-aminotrifluorotoluene was added dropwise. After the addition was completed, stirring was continued in an ice-water bath for at least half an hour, and then the temperature was gradually raised to room temperature. Stirring was carried out at room temperature for 20 hours. After the reaction was completed, the mixture was poured into ice water with a volume twice that of the reaction solution, the solid was collected by filtration, and washed three times with ice water. After drying, it was purified by silica gel column chromatography (eluent volume ratio: ethyl acetate / petroleum ether = 1:2) to obtain a flame retardant after drying.

[0078] Example 3:

[0079] A high-temperature resistant and flame-retardant composite current collector base film is different from Example 1 only in that the preparation method of the flame retardant is different.

[0080] The preparation method of the flame retardant includes:

[0081] S1, chlorination treatment:

[0082] Weigh 0.66 g of 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (TCT-COOH) and add it to 10 mL of thionyl chloride. Stir thoroughly under a nitrogen atmosphere and an ice-water bath. Then gradually raise the temperature to 86°C and reflux with stirring for 12 hours. After the reaction is complete, remove the excess thionyl chloride by rotary evaporation and dry in vacuo to obtain the intermediate product (TCT-COCl).

[0083] S2. Amidation reaction:

[0084] 1 g of the intermediate product (TCT-COCl) was weighed and added to 40 mL of tetrahydrofuran (solvent). Pyridine was added as a catalyst in an amount of 6.5 times the mass of the intermediate product. The mixture was stirred evenly under a nitrogen atmosphere and an ice-water bath. Then, 1.6 g of 3-aminotrifluorotoluene was added dropwise. After the addition was completed, stirring was continued in an ice-water bath for at least half an hour, and then the temperature was gradually raised to room temperature. Stirring was carried out at room temperature for 30 hours. After the reaction was completed, the mixture was poured into ice water 3 times the volume of the reaction solution, the solid was collected by filtration, and washed 3 times with ice water. After drying, it was purified by silica gel column chromatography (eluent volume ratio: ethyl acetate / petroleum ether = 1:2) to obtain a flame retardant after drying.

[0085] Example 4:

[0086] A high-temperature resistant and flame-retardant composite current collector base film, comprising the following components in parts by weight:

[0087] 100 parts of polyphenylene sulfide resin (PPS), 15 parts of carbon fiber, 10 parts of flame retardant, 2 parts of plasticizer, 0.6 parts of compatibilizer, 0.2 parts of coupling agent, 1 part of lubricant, 0.3 parts of anti-blocking agent and 0.5 parts of antioxidant.

[0088] Among them, polyphenylene sulfide resin (PPS) is a linear high molecular weight polyphenylene sulfide resin (PPS) with a density of 1.35g / cm 3 , melt index 60g / 10min (330℃, 5kg); carbon fiber is chopped carbon fiber with a length of 3-5mm and a diameter of 5-8μm; plasticizer is triethyl citrate (TEC).

[0089] Among them, the compatibilizer is polypropylene grafted glycidyl methacrylate (PP-g-GMA), the grafting rate is 0.8%, and the melt index is 120g / 10min (190℃, 2.16kg).

[0090] Among them, the coupling agent is KH-560; the lubricant is magnesium stearate; the anti-adhesive agent is nano-scale silicon dioxide, and the particle size is preferably 20-50nm; the antioxidant is a mixture of main antioxidant 1010 and auxiliary antioxidant 168 in a mass ratio of 1:1.

[0091] The preparation method of the flame retardant is the same as that in Example 1 of the present invention.

[0092] The preparation method of the above-mentioned high temperature resistant flame retardant composite current collector base film is the same as that in Example 1.

[0093] Example 5:

[0094] A high-temperature resistant and flame-retardant composite current collector base film, comprising the following components in parts by weight:

[0095] 100 parts of polyphenylene sulfide resin (PPS), 25 parts of carbon fiber, 30 parts of flame retardant, 4 parts of plasticizer, 2 parts of compatibilizer, 0.8 parts of coupling agent, 3 parts of lubricant, 1 part of anti-blocking agent and 1.5 parts of antioxidant.

[0096] Among them, polyphenylene sulfide resin (PPS) is a linear high molecular weight polyphenylene sulfide resin (PPS) with a density of 1.35g / cm 3 , melt index 60g / 10min (330℃, 5kg); carbon fiber is chopped carbon fiber with a length of 3-5mm and a diameter of 5-8μm; plasticizer is trioctyl citrate (TOC).

[0097] Among them, the compatibilizer is polypropylene grafted glycidyl methacrylate (PP-g-GMA), the grafting rate is 0.8%, and the melt index is 120g / 10min (190℃, 2.16kg).

[0098] Among them, the coupling agent is KH-570; the lubricant is zinc stearate; the anti-blocking agent is nano-scale silicon dioxide, and the particle size is preferably 20-50nm; the antioxidant is a mixture of main antioxidant 1010 and auxiliary antioxidant 168 in a mass ratio of 3:1.

[0099] The preparation method of the flame retardant is the same as that in Example 1 of the present invention.

[0100] The preparation method of the above-mentioned high temperature resistant flame retardant composite current collector base film is the same as that in Example 1.

[0101] Comparative Example 1:

[0102] A composite current collector base film, which differs from Example 1 in that all flame retardants are replaced by common triazine flame retardant: 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (TCT-COOH), and the other components are the same as those in Example 1.

[0103] Comparative Example 2:

[0104] A composite current collector base film differs from Example 1 in that the flame retardant is replaced with a common triazine flame retardant: a mixture of 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (TCT-COOH) and 3-aminobenzotrifluoride, with the mass ratio of TCT-COOH to 3-aminobenzotrifluoride being 1:1.4. Other components are the same as those in Example 1.

[0105] Experimental testing:

[0106] In order to more clearly illustrate the content of the present invention, comparative examples 1-2 are provided using Example 1 of the present invention as a benchmark.

[0107] The mechanical strength, heat resistance and flame retardancy, and surface properties of Example 1 and Comparative Examples 1-2 were tested respectively.

[0108] The specific tests are as follows:

[0109] 1. The test items and reference standards for mechanical strength include:

[0110] Tensile strength and elongation at break: GB / T 1040.3-2006, room temperature, rate 50 mm / min; elastic modulus: ISO 527-1:2019; notched impact strength: GB / T 1043.1-2008, specimen dimensions: 80 mm × 10 mm × 4 mm, notch depth 2 mm, angle 45°.

[0111] Table 1 Mechanical strength test results

[0112]

[0113] 2. The test items and reference standards for heat resistance and flame retardancy include:

[0114] Heat Deflection Temperature: GB / T 1634.2-2019; UL94 Flame Retardant Rating: UL94-2018; Limiting Oxygen Index (LOI): GB / T 2406.2-2009; Thermal Shrinkage: GB / T 13519-2016, 200°C, 30 min constant temperature.

[0115] The test results are shown in Table 2:

[0116] Table 2 Test results of heat resistance and flame retardancy

[0117]

[0118] 3. Surface performance test items and reference standards include:

[0119] Electrolyte immersion tensile strength retention: Tensile strength retention was measured in 85°C electrolyte (1M LiPF6 EC / DEC) for 7 days. Volume swelling ratio: GB / T 1034-2008. Metal adhesion: GB / T 2792-2014, using a 90° peel test with copper (Cu) at a peel speed of 50 mm / min and a copper foil width of 3.18 mm.

[0120] Table 3 Test results of surface properties

[0121]

[0122] The above test results show that the composite current collector base film prepared in Example 1 of the present invention exhibits superior mechanical strength, heat resistance, flame retardancy, and surface properties. The flame retardant used in Example 1 of the present invention achieves synergistic flame retardancy through chemical bonding, outperforming the conventional triazine flame retardant used in Comparative Example 1 in all aspects, and significantly improving safety compared to the physical mixing system in Comparative Example 2.

[0123] In the description of this specification, reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification.

[0124] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A high temperature resistant flame retardant composite current collector base film, characterized in that: Calculated by weight, it includes the following ingredients: 100 parts of polyphenylene sulfide resin, 15-25 parts of carbon fiber, 10-30 parts of flame retardant, 2-4 parts of plasticizer, 0.6-2 parts of compatibilizer, 0.2-0.8 parts of coupling agent, 1-3 parts of lubricant, 0.3-1 parts of anti-blocking agent and 0.5-1.5 parts of antioxidant; The flame retardant is a product obtained by chlorinating 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine and then reacting it with 3-aminobenzotrifluoride for an amidation reaction. The carbon fibers are surface treated with a coupling agent before use.

2. The high temperature resistant flame retardant composite current collector base film according to claim 1, characterized in that: The polyphenylene sulfide resin is a linear high molecular weight polyphenylene sulfide resin with a density of 1.34-1.36 g / cm 3 The melt index is 20-80 g / 10 min at 330° C. and 5 kg. The carbon fiber is chopped carbon fiber with a length of 3-5 mm and a diameter of 5-8 μm.

3. The high temperature resistant flame retardant composite current collector base film according to claim 1, characterized in that: The plasticizer is one or a combination of epoxy soybean oil, triethyl citrate, tributyl citrate, and trioctyl citrate.

4. The high temperature resistant flame retardant composite current collector base film according to claim 1, characterized in that: The compatibilizer is polypropylene grafted with glycidyl methacrylate or polypropylene grafted with maleic anhydride.

5. The high temperature resistant flame retardant composite current collector base film according to claim 1, characterized in that: The coupling agent is one or more combinations of KH-550, KH-560, and KH-570; the lubricant is one or more combinations of calcium stearate, magnesium stearate, zinc stearate, and barium stearate; the anti-blocking agent is nano-scale silicon dioxide; and the antioxidant is a mixture of a main antioxidant 1010 and an auxiliary antioxidant 168 in a mass ratio of 1-3:

1.

6. The high temperature resistant flame retardant composite current collector base film according to claim 1, characterized in that: The preparation method of the flame retardant comprises: S1. Weigh 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine and add it to thionyl chloride. Stir thoroughly under a nitrogen atmosphere and an ice-water bath. Then gradually raise the temperature to 78-86°C and reflux with stirring for 12-24 hours. After the reaction is completed, remove the thionyl chloride and dry the mixture to obtain an intermediate product. S2. Weigh the intermediate product and add it to tetrahydrofuran, add a basic catalyst, stir evenly under a nitrogen atmosphere and an ice-water bath, then add 3-aminotrifluorotoluene dropwise. After the addition is complete, continue stirring in the ice-water bath for at least half an hour, then gradually warm to room temperature, stir at room temperature for 20-30 hours, and after the reaction is completed, purify to obtain a flame retardant.

7. The high temperature resistant flame retardant composite current collector base film according to claim 6, characterized in that: In the S1, the mass volume ratio of 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine and thionyl chloride is (0.22-0.66) g:(2-10) mL.

8. The high temperature resistant flame retardant composite current collector base film according to claim 6, characterized in that: In the above-mentioned S2, the mass volume ratio of the intermediate product, 3-aminotrifluorotoluene and tetrahydrofuran is 1 g: (1.2-1.6) g: (20-40) mL.

9. The high temperature resistant flame retardant composite current collector base film according to claim 6, characterized in that: In the step S2, the alkaline catalyst is pyridine, and the amount of pyridine added is 4.2-6.5 times the mass of the intermediate product.

10. A method for preparing a high-temperature resistant flame-retardant composite current collector base film, applicable to the high-temperature resistant flame-retardant composite current collector base film according to claim 1, characterized in that: The following steps are involved: Step 1: weigh PPS resin and dry it in vacuum at 120° C. for 4 hours; and treat the carbon fiber surface with a coupling agent before use; Step 2: Add the dried PPS resin, flame retardant and compatibilizer into a high-speed mixer, stir and mix at a speed of 600-1000 rpm for 3-6 minutes, then add the plasticizer and lubricant, continue to stir and mix for 2-3 minutes, then add the anti-blocking agent and antioxidant, continue to stir and mix for 4-5 minutes, and finally add the carbon fiber treated with the coupling agent, stir and mix at a speed of 400-600 rpm for 1-3 minutes to obtain a mixture; Step 3: introducing the mixed material into a twin-screw extruder with a length-to-diameter ratio of L / D=40:1, and melt-extruding in a temperature range of 290-320°C (zone I 290°C, zone II 310°C, zone III 320°C, and die head 305°C) to obtain a mixed melt; Step 4: The mixed melt was cast through a T-die (die lip gap 0.8 mm) onto a cooling roller (25°C) to form a 200 μm thick casting sheet; Step 5: preheating the cast sheet and then longitudinally stretching it, wherein the preheating temperature is 100-120°C, the time is 30s, the stretching temperature is 95-115°C, and the stretching ratio is 3.2 times; Step 6: preheating the cast sheet and then transversely stretching it, wherein the preheating temperature is 100-110°C, the time is 30s, the stretching temperature is 110-125°C, and the stretching ratio is 3.5 times; Step 7: heat-set the stretched cast sheet at 210-250°C for 10s, and perform corona treatment with the following parameters: power 8kW, speed 5m / min. After corona treatment, the sheet is cut and rolled up with the cutting tension controlled at 20N to obtain a high-temperature resistant and flame-retardant composite current collector base film.

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