A high-temperature-resistant collector base film and a preparation method thereof

Abstract

The application relates to the field of current collector films, in particular to a high-temperature-resistant current collector base film and a preparation method thereof. The current collector base film comprises the following components in parts by weight: 75-85 parts of PET resin, 8-12 parts of a high-temperature-resistant modifier, 5-8 parts of silane-modified nano-silicon dioxide, 0.5-1.5 parts of a lubricant, 0.5-1.5 parts of a stabilizer, 1-3 parts of a nucleating agent and 0.2-1 part of an antioxidant. The current collector base film takes the PET resin as the main material, adds the high-temperature-resistant modifier and the silane-modified nano-silicon dioxide as the reinforcing modifier, and further adds other auxiliary agents. The current collector base film prepared by the application has excellent high-temperature resistance, good mechanical strength, good flame retardance, excellent comprehensive performance and is particularly suitable for preparing a composite current collector for a high-safety and long-service-life lithium battery.

Description

Technical Field

[0001] This invention relates to the field of current collector membranes, and more specifically to a high-temperature resistant current collector base membrane and its preparation method. Background Technology

[0002] With the rapid development of new energy vehicles, energy storage power stations, and consumer electronics, higher requirements have been placed on the energy density, power density, and safety performance of lithium-ion batteries. As a key component of lithium-ion batteries, the current collector plays a crucial role in collecting current and carrying active materials; its performance directly affects the battery's internal resistance, cycle life, and safety. Currently, commercially available lithium-ion batteries primarily use aluminum foil as the positive electrode current collector and copper foil as the negative electrode current collector.

[0003] However, traditional metal foil current collectors have several limitations: First, their weight restricts further improvements in battery energy density; second, metal foil is prone to corrosion and breakage during long-term battery cycling, affecting battery life; and third, and most critically, when a battery experiences thermal runaway due to internal short circuits, overcharging, or other reasons, the internal temperature rises sharply. Aluminum foil has a melting point of approximately 660℃, copper foil approximately 1083℃, while commonly used polyolefin separators (such as PE and PP) typically have a closed-cell temperature between 135-165℃ and a melting temperature between 150℃-170℃. In the early stages of thermal runaway, the separator melts and contracts, resulting in extremely large contact areas between the positive and negative electrodes, generating a huge short-circuit current and releasing a large amount of heat instantaneously. At this point, the temperature may have far exceeded the melting point of the aluminum foil, causing it to melt and break. The positive electrode active material separates from the current collector, leading to uneven current distribution throughout the battery, accelerating the thermal runaway process, and even causing serious safety accidents such as fires and explosions.

[0004] Currently, commonly used composite current collectors typically employ a sandwich structure of "metal-polymer base film-metal," with polyethylene terephthalate (PET) being the most frequently used polymer base film. However, PET has a glass transition temperature of approximately 70°C and a melting point of approximately 250°C, resulting in a relatively low heat resistance. At high temperatures, it will still experience severe shrinkage and melting, failing to effectively support the metal layer and ultimately leading to the failure of the current collector structure.

[0005] Therefore, developing a novel current collector base film that combines excellent high-temperature resistance and good mechanical strength is of vital importance for the preparation of high-safety, high-performance lithium-ion batteries and for promoting the development of new energy vehicles and energy storage industries. Summary of the Invention

[0006] To address the problems existing in the prior art, the purpose of this invention is to provide a high-temperature resistant current collector base film and its preparation method.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] In a first aspect, the present invention provides a high-temperature resistant current collector base film, comprising, by weight parts:

[0009] 75-85 parts PET resin, 8-12 parts high-temperature resistant modifier, 5-8 parts silane-modified nano silica, 0.5-1.5 parts lubricant, 0.5-1.5 parts stabilizer, 1-3 parts nucleating agent and 0.2-1 parts antioxidant.

[0010] Preferably, the density of the PET resin is 1.38-1.40 g / cm³. 3 The melt flow index is 15-25 g / 10 min (280℃ / 2.16 kg).

[0011] Preferably, the high-temperature resistant modifier is prepared by epoxy-functionalized benzoxazine and o-aminobenzenesulfonamide through an epoxy ring-opening reaction.

[0012] Preferably, the silane-modified nano-silica is obtained by modifying nano-silica with a silane coupling agent KH-570.

[0013] Preferably, the method for preparing the silane-modified nano-silica includes:

[0014] Weigh out silane coupling agent KH-570 and nano silica and add them to an ethanol solution. After sonication and homogenization, reflux at 60-80℃ for 3-8 hours. After centrifugation, washing and drying, silane-modified nano silica is obtained.

[0015] Preferably, the ratio of the nano-silica, silane coupling agent KH-570 and ethanol solution is 1g:(0.18-0.32)g:(6-12)mL.

[0016] Preferably, the lubricant is at least one of calcium stearate, zinc stearate, and sodium stearate.

[0017] Preferably, the stabilizer is at least one of carbodiimide, oxazoline, and isocyanate.

[0018] Preferably, the nucleating agent is ultrafine talc powder with a particle size of 100-200 nm.

[0019] Preferably, the antioxidant is a mixture of primary antioxidant 1010 and secondary antioxidant 168, and the mass ratio of primary antioxidant 1010 to secondary antioxidant 168 is 2-4:1.

[0020] Preferably, the preparation method of the epoxy-functionalized benzoxazine includes:

[0021] p-Allylphenol and n-octylamine were mixed into 1,4-dioxane, nitrogen was introduced as a protective gas, paraformaldehyde was added, and the mixture was stirred at 90-120℃ for 6-8 hours. After the reaction was completed, the mixture was filtered and post-treated to obtain allyl-functionalized benzoxazine. Allyl-functionalized benzoxazine was added to dichloromethane, and m-chloroperoxybenzoic acid was added under ice-water bath conditions. The mixture was stirred for 2-3 hours, and the temperature was gradually raised to room temperature. The reaction was continued to be stirred for 8-12 hours. The mixture was washed and dried to obtain epoxy-functionalized benzoxazine.

[0022] Preferably, the ratio of p-allylphenol, n-octylamine, paraformaldehyde and 1,4-dioxane is 1.34 g:(1.21-1.37) g:(0.6-0.8) g:(40-60) mL.

[0023] Preferably, the ratio of allyl-functionalized benzoxazine, m-chloroperoxybenzoic acid and dichloromethane is 1.67 g:(0.96-1.15) g:(40-60) mL.

[0024] Preferably, the preparation method of the high-temperature resistant modifier includes:

[0025] Weigh out o-aminobenzenesulfonamide and add it to toluene. Stir well under nitrogen protection and heat to 75-85℃. Gradually add epoxy-functionalized benzoxazine and continue stirring until well mixed. Then add catalyst and keep warm and stir for 8-10 hours. After the reaction is complete, wash with water, rotary evaporate and vacuum dry in sequence to obtain high temperature resistant modifier.

[0026] Preferably, the ratio of epoxy-functionalized benzoxazine, o-aminobenzenesulfonamide and toluene is 1g:(0.23-0.38)g:(5-15)mL.

[0027] Preferably, the catalyst is triethylamine, and the amount added is 0.8%-1.6% of the mass of the epoxy-functionalized benzoxazine.

[0028] Secondly, the present invention provides a method for preparing a high-temperature resistant current collector base film, comprising the following steps:

[0029] Step 1: Vacuum-dried PET resin, high-temperature resistant modifier, nano-inorganic filler, lubricant, stabilizer, nucleating agent and antioxidant are added to a high-speed mixer in the proportion of parts by weight and mixed thoroughly to obtain a premix.

[0030] Step 2: The premixed material is fed into a twin-screw extruder, melt-blended, extruded, cooled, and pelletized to obtain composite masterbatch;

[0031] Step 3: After drying the composite masterbatch, it is fed into a single-screw extrusion casting machine and formed into a casting sheet on a cooling roller. The casting sheet is then biaxially stretched and wound up to obtain a high-temperature resistant current collector base film.

[0032] The beneficial effects of this invention are as follows:

[0033] 1. This invention prepares a current collector base film. The current collector base film uses PET resin as the main material, with the addition of a high-temperature resistant modifier and silane-modified nano-silica as reinforcing modifiers, along with other additives. The current collector base film prepared by this invention possesses excellent high-temperature resistance and good mechanical strength, as well as good flame retardancy. Its comprehensive performance is excellent, making it particularly suitable for preparing high-safety, long-life composite current collectors for lithium batteries.

[0034] 2. This invention introduces a high-temperature resistant modifier into the base film composition. The active groups in the structure can strongly interact with the PET matrix and participate in the crystallization process, thereby improving the compatibility with the matrix. In addition, the high-temperature resistant modifier, used synergistically with silane-modified nano-silica, can significantly improve the glass transition temperature and thermal dimensional stability of the base film. The benzoxazine and sulfonamide structures it contains also endow the material with certain flame retardancy.

[0035] 3. The high-temperature resistant modifier added in this invention is prepared by an epoxy-functionalized benzoxazine and o-aminobenzenesulfonamide through an epoxy ring-opening reaction. The epoxy-functionalized benzoxazine is prepared by first synthesizing allyl-functionalized benzoxazine, and then epoxidizing the allyl group to introduce an active epoxy group into the benzoxazine monomer; the epoxy-functionalized benzoxazine undergoes an epoxy-amino combination reaction with o-aminobenzenesulfonamide containing an amino group to prepare a benzoxazine compound containing a benzenesulfonamide group. Detailed Implementation

[0036] To better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. While 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 to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0037] The present invention will be further described below with reference to the following embodiments.

[0038] Example 1

[0039] A high-temperature resistant current collector base film, comprising, by weight parts:

[0040] 80 parts PET resin, 10 parts high-temperature modifier, 6 parts silane-modified nano silica, 1 part lubricant, 1.2 parts stabilizer, 2 parts nucleating agent and 0.7 parts antioxidant.

[0041] The density of the PET resin is 1.39 g / cm³. 3The melt flow index is 22 g / 10 min (280℃ / 2.16 kg).

[0042] The lubricant is calcium stearate; the stabilizer is carbodiimide; and the nucleating agent is ultrafine talc powder with a particle size of 100-200 nm.

[0043] The antioxidant is a mixture of primary antioxidant 1010 and secondary antioxidant 168, with a mass ratio of primary antioxidant 1010 to secondary antioxidant 168 of 3:1.

[0044] The method for preparing the silane-modified nano-silica includes:

[0045] 0.26g of silane coupling agent KH-570 and 1g of 100nm nano-silica were weighed and added to 8mL of 80wt% ethanol solution. After ultrasonic homogenization, the solution was refluxed at 70℃ for 5h. After centrifugation, washing and drying, silane-modified nano-silica was obtained.

[0046] The preparation method of the high-temperature resistant modifier includes:

[0047] S1. Preparation of epoxy-functionalized benzoxazine:

[0048] a. Add 1.34 g of allylphenol and 1.29 g of n-octylamine to 50 mL of 1,4-dioxane, stir thoroughly to dissolve, then purge with nitrogen as a protective gas, slowly add 0.7 g of paraformaldehyde, and stir the reaction at 110 °C for 7 h. After the reaction is complete, pour the mixture into 2 times the volume of n-hexane to precipitate the product, filter to collect the precipitate, wash it 3 times with n-hexane, and dry it in a vacuum oven at 60 °C for 18 h to obtain a white solid powder, which is allyl-functionalized benzoxazine.

[0049] b. Add 1.67g of allyl-functionalized benzoxazine to 50mL of dichloromethane, disperse it evenly in an ice-water bath, and then slowly add 1.03g of m-chloroperoxybenzoic acid, controlling the temperature not to exceed 10℃. After all the acid has been added, stir in an ice-water bath for 2h, then gradually raise the temperature to room temperature and continue stirring for 10h. Wash the mixture three times with saturated sodium bicarbonate solution, then wash it three times with pure water. After removing the water, dry it under reduced pressure to remove the solvent, and obtain a pale yellow solid powder, which is epoxy-functionalized benzoxazine.

[0050] S2. Preparation of high-temperature resistant modifier:

[0051] Weigh 0.31 g of o-aminobenzenesulfonamide and add it to 10 mL of toluene. Stir well under nitrogen protection and heat to 80 °C. Gradually add 1 g of epoxy-functionalized benzoxazine over half an hour and continue stirring until well mixed. Then add the catalyst triethylamine, the amount of which is 1.2% of the mass of epoxy-functionalized benzoxazine. Keep the mixture warm and stir for 10 h. After the reaction is complete, cool the reaction solution to room temperature, wash with water until neutral, remove the solvent by rotary evaporation, and dry under vacuum at 80 °C for 8 h to obtain the high-temperature resistant modifier.

[0052] The preparation method of the above-mentioned high-temperature resistant current collector base film includes the following steps:

[0053] Step 1: Vacuum dry PET resin at 140℃ for more than 6 hours, then add it to a high-speed mixer in the proportion of parts by weight of high-temperature modifier, nano-inorganic filler, lubricant, stabilizer, nucleating agent and antioxidant, and mix thoroughly for 10 minutes to obtain premix.

[0054] Step 2: The premixed material is fed into a twin-screw extruder, melt-blended, extruded, cooled, and pelletized at a temperature range of 260-285℃ to obtain composite masterbatch;

[0055] Step 3: After drying, the composite masterbatch is fed into a single-screw extrusion casting machine and formed into a casting sheet on a cooling roller through a T-die. The casting sheet is then subjected to bidirectional stretching in the longitudinal (MD) and transverse (TD) directions. The longitudinal stretching temperature is 95℃ with a stretching ratio of 3.5:1, and the transverse stretching temperature is 105℃ with a stretching ratio of 4:1. Afterward, it is heat-set at 240℃ for 10 seconds and then wound up to obtain a high-temperature resistant current collector base film.

[0056] Example 2

[0057] A high-temperature resistant current collector base film, comprising, by weight parts:

[0058] 75 parts PET resin, 8 parts high-temperature modifier, 5 parts silane-modified nano silica, 0.5 parts lubricant, 0.5 parts stabilizer, 1 part nucleating agent and 0.2 parts antioxidant.

[0059] The density of the PET resin is 1.39 g / cm³. 3 The melt flow index is 22 g / 10 min (280℃ / 2.16 kg).

[0060] The lubricant is zinc stearate; the stabilizer is oxazoline; and the nucleating agent is ultrafine talc powder with a particle size of 100-200 nm.

[0061] The preparation method of the high-temperature resistant modifier is the same as that in Example 1.

[0062] The antioxidant is a mixture of primary antioxidant 1010 and secondary antioxidant 168, and the mass ratio of primary antioxidant 1010 to secondary antioxidant 168 is 2:1.

[0063] The method for preparing the silane-modified nano-silica includes:

[0064] 0.18g of silane coupling agent KH-570 and 1g of 100nm nano-silica were weighed and added to 6mL of 80wt% ethanol solution. After ultrasonic homogenization, the solution was refluxed at 60℃ for 8h. After centrifugation, washing and drying, silane-modified nano-silica was obtained.

[0065] The preparation method of the above-mentioned high-temperature resistant current collector base film includes the following steps:

[0066] Step 1: Vacuum dry PET resin at 135℃ for more than 6 hours, then add it to a high-speed mixer in the proportion of parts by weight of high-temperature modifier, nano-inorganic filler, lubricant, stabilizer, nucleating agent and antioxidant, and mix thoroughly for 5 minutes to obtain premix.

[0067] Step 2: The premixed material is fed into a twin-screw extruder, melt-blended, extruded, cooled, and pelletized at a temperature range of 260-285℃ to obtain composite masterbatch;

[0068] Step 3: After drying, the composite masterbatch is fed into a single-screw extrusion casting machine and formed into a casting sheet on a cooling roller through a T-die. The casting sheet is then subjected to bidirectional stretching in the longitudinal (MD) and transverse (TD) directions. The longitudinal stretching temperature is 90℃ with a stretching ratio of 3:1, and the transverse stretching temperature is 100℃ with a stretching ratio of 3.5:1. Afterward, it is heat-set at 230℃ for 15s and then wound up to obtain a high-temperature resistant current collector base film.

[0069] Example 3

[0070] A high-temperature resistant current collector base film, comprising, by weight parts:

[0071] 85 parts PET resin, 12 parts high-temperature modifier, 8 parts silane-modified nano silica, 1.5 parts lubricant, 1.5 parts stabilizer, 3 parts nucleating agent and 1 part antioxidant.

[0072] The density of the PET resin is 1.39 g / cm³. 3 The melt flow index is 22 g / 10 min (280℃ / 2.16 kg).

[0073] The lubricant is sodium stearate; the stabilizer is isocyanate; and the nucleating agent is ultrafine talc powder with a particle size of 100-200 nm.

[0074] The preparation method of the high-temperature resistant modifier is the same as that in Example 1.

[0075] The antioxidant is a mixture of primary antioxidant 1010 and secondary antioxidant 168, with a mass ratio of primary antioxidant 1010 to secondary antioxidant 168 of 4:1.

[0076] The method for preparing the silane-modified nano-silica includes:

[0077] 0.32g of silane coupling agent KH-570 and 1g of 100nm nano-silica were weighed and added to 12mL of 80wt% ethanol solution. After ultrasonic homogenization, the solution was refluxed at 80℃ for 3h. After centrifugation, washing and drying, silane-modified nano-silica was obtained.

[0078] The preparation method of the above-mentioned high-temperature resistant current collector base film includes the following steps:

[0079] Step 1: Vacuum dry PET resin at 145℃ for more than 6 hours, then add it to a high-speed mixer in the proportion of parts by weight of high-temperature modifier, nano-inorganic filler, lubricant, stabilizer, nucleating agent and antioxidant, and mix thoroughly for 10 minutes to obtain premix.

[0080] Step 2: The premixed material is fed into a twin-screw extruder, melt-blended, extruded, cooled, and pelletized at a temperature range of 285°C to obtain composite masterbatch;

[0081] Step 3: After drying, the composite masterbatch is fed into a single-screw extrusion casting machine and formed into a casting sheet on a cooling roller through a T-die. The casting sheet is then subjected to bidirectional stretching in the longitudinal (MD) and transverse (TD) directions. The longitudinal stretching temperature is 100℃ and the stretching ratio is 3.5:1; the transverse stretching temperature is 110℃ and the stretching ratio is 4:1. After that, it is heat-set at 245℃ for 5 seconds. After winding, a high-temperature resistant current collector base film is obtained.

[0082] Example 4

[0083] A high-temperature resistant current collector base film differs from Example 1 only in the preparation method of the high-temperature resistant modifier.

[0084] The preparation method of the high-temperature resistant modifier includes:

[0085] S1. Preparation of epoxy-functionalized benzoxazine:

[0086] a. Add 1.34 g of allylphenol and 1.21 g of n-octylamine to 40 mL of 1,4-dioxane, stir thoroughly to dissolve, then purge with nitrogen as a protective gas, slowly add 0.6 g of paraformaldehyde, and stir the reaction at 90-120 °C for 6 h. After the reaction is complete, pour the mixture into 2 times the volume of n-hexane to precipitate the product, filter to collect the precipitate, wash it 3 times with n-hexane, and dry it in a vacuum oven at 60 °C for 18 h to obtain a white solid powder, which is allyl-functionalized benzoxazine.

[0087] b. Add 1.67g of allyl-functionalized benzoxazine to 40mL of dichloromethane, disperse it evenly in an ice-water bath, and then slowly add 0.96g of m-chloroperoxybenzoic acid, controlling the temperature not to exceed 10℃. After all the acid has been added, stir in an ice-water bath for 2h, then gradually raise the temperature to room temperature and continue stirring for 8h. Wash the mixture three times with saturated sodium bicarbonate solution, then wash it three times with pure water. After removing the water, dry it under reduced pressure to remove the solvent, and obtain a pale yellow solid powder, which is epoxy-functionalized benzoxazine.

[0088] S2. Preparation of high-temperature resistant modifier:

[0089] Weigh 0.23 g of o-aminobenzenesulfonamide and add it to 5 mL of toluene. Stir well under nitrogen protection and heat to 75 °C. Gradually add 1 g of epoxy-functionalized benzoxazine over half an hour and continue stirring until well mixed. Then add the catalyst triethylamine, which is 0.8% of the mass of epoxy-functionalized benzoxazine. Keep the mixture warm and stir for 10 h. After the reaction is complete, cool the reaction solution to room temperature, wash with water until neutral, remove the solvent by rotary evaporation, and dry under vacuum at 80 °C for 6 h to obtain the high-temperature resistant modifier.

[0090] Example 5

[0091] A high-temperature resistant current collector base film differs from Example 1 only in the preparation method of the high-temperature resistant modifier.

[0092] The preparation method of the high-temperature resistant modifier includes:

[0093] S1. Preparation of epoxy-functionalized benzoxazine:

[0094] a. Add 1.34 g of allylphenol and 1.37 g of n-octylamine to 60 mL of 1,4-dioxane, stir thoroughly to dissolve, then purge with nitrogen as a protective gas, slowly add 0.8 g of paraformaldehyde, and stir the reaction at 120 °C for 8 h. After the reaction is complete, pour the mixture into 2 times the volume of n-hexane to precipitate the product, filter to collect the precipitate, wash it 3 times with n-hexane, and dry it in a vacuum oven at 60 °C for 18 h to obtain a white solid powder, which is allyl-functionalized benzoxazine.

[0095] b. Add 1.67g of allyl-functionalized benzoxazine to 60mL of dichloromethane, disperse it evenly in an ice-water bath, and then slowly add 1.15g of m-chloroperoxybenzoic acid, controlling the temperature not to exceed 10℃. After all the acid has been added, stir in an ice-water bath for 3h, then gradually raise the temperature to room temperature and continue stirring for 12h. Wash the mixture three times with saturated sodium bicarbonate solution, then wash it three times with pure water. After removing the water, dry it under reduced pressure to remove the solvent, and obtain a pale yellow solid powder, which is epoxy-functionalized benzoxazine.

[0096] S2. Preparation of high-temperature resistant modifier:

[0097] Weigh 0.38 g of o-aminobenzenesulfonamide and add it to 15 mL of toluene. Stir well under nitrogen protection and heat to 85 °C. Gradually add 1 g of epoxy-functionalized benzoxazine over half an hour and continue stirring until well mixed. Then add the catalyst triethylamine, which is 1.6% of the mass of epoxy-functionalized benzoxazine. Keep the mixture warm and stir for 8 h. After the reaction is complete, cool the reaction solution to room temperature, wash with water until neutral, remove the solvent by rotary evaporation, and dry under vacuum at 80 °C for 12 h to obtain the high-temperature resistant modifier.

[0098] Comparative Example 1

[0099] A current collector-based membrane differs from Example 1 only in that the high-temperature resistant modifier is replaced with an epoxy-functionalized benzoxazine.

[0100] Comparative Example 2

[0101] A current collector base film differs from Example 1 only in that the high-temperature modifier is replaced with a mixture of epoxy-functionalized benzoxazine and benzenesulfonamide, with a mass ratio of epoxy-functionalized benzoxazine to benzenesulfonamide of 1:0.31.

[0102] Experimental Example

[0103] The performance of the current collector base films prepared in Example 1 and Comparative Examples 1-2 was tested, and all tests were conducted in accordance with national or international standards.

[0104] The testing items include:

[0105] 1. Mechanical strength: tensile strength (refer to GB / T 1040.3-2006), elongation at break (refer to GB / T 1040.3-2006), modulus of elasticity (refer to GB / T 1040.3-2006).

[0106] 2. High temperature resistance: Vicat softening temperature (refer to GB / T 1633-2000), heat shrinkage rate (200℃, 30min, refer to GB / T 12027-2004);

[0107] 3. Flame retardancy: Limiting oxygen index (refer to GB / T 2406.2-2009) and UL94 rating (thickness 0.1mm, refer to ANSI / UL-94-1985).

[0108] The test results are shown in Tables 1 and 2:

[0109] Table 1. Test results of mechanical properties of different current collector base films

[0110]

[0111] Table 2. Test results of high temperature resistance and flame retardancy of different current collector base films.

[0112]

[0113] As can be seen from Tables 1 and 2, the current collector base film prepared in Example 1 of this invention exhibits excellent mechanical properties, high-temperature resistance, and flame retardancy. The properties of Comparative Example 1 are all weaker than those of Example 1, particularly the significant decrease in heat shrinkage and flame retardancy. This may be because the chemical connection or interaction between the epoxy-functionalized benzoxazine and the PET molecular chain is weaker, and the lack of sulfonamide groups leads to a decrease in thermal stability and flame retardancy. The overall performance of Comparative Example 2 is weaker than the other two, especially in terms of thermal stability. This may be because the addition of low-melting-point benzenesulfonamide lowers the softening temperature of the entire system, significantly affecting shrinkage performance.

[0114] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0115] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A high-temperature resistant current collector base film, characterized in that, Calculated by weight, including: 75-85 parts PET resin, 8-12 parts high-temperature modifier, 5-8 parts silane-modified nano-silica, 0.5-1.5 parts lubricant, 0.5-1.5 parts stabilizer, 1-3 parts nucleating agent and 0.2-1 parts antioxidant; The high-temperature resistant modifier is prepared by reacting and combining epoxy-functionalized benzoxazine and o-aminobenzenesulfonamide. The preparation method of the epoxy-functionalized benzoxazine includes: p-Allylphenol and n-octylamine were mixed into 1,4-dioxane, nitrogen was introduced as a protective gas, paraformaldehyde was added, and the mixture was stirred at 90-120℃ for 6-8 hours. After the reaction was completed, the mixture was filtered and post-treated to obtain allyl-functionalized benzoxazine. Allyl-functionalized benzoxazine was added to dichloromethane, and m-chloroperoxybenzoic acid was added under ice-water bath conditions. The mixture was stirred for 2-3 hours, and the temperature was gradually raised to room temperature. The reaction was continued to be stirred for 8-12 hours. The mixture was washed and dried to obtain epoxy-functionalized benzoxazine.

2. The high-temperature resistant current collector substrate film according to claim 1, characterized in that, The density of the PET resin is 1.38-1.40 g / cm³. 3 The melt index is 15-25 g / 10 min at 280℃ and 2.16 kg.

3. The high-temperature resistant current collector substrate film according to claim 1, characterized in that, The silane-modified nano-silica is obtained by modifying nano-silica with the silane coupling agent KH-570.

4. The high-temperature resistant current collector substrate film according to claim 1, characterized in that, The lubricant is at least one of calcium stearate, zinc stearate, and sodium stearate; the stabilizer is at least one of carbodiimide, oxazoline, and isocyanate; and the nucleating agent is ultrafine talc powder with a particle size of 100-200 nm.

5. The high-temperature resistant current collector substrate film according to claim 1, characterized in that, The antioxidant is a mixture of primary antioxidant 1010 and secondary antioxidant 168, with a mass ratio of primary antioxidant 1010 to secondary antioxidant 168 of 2-4:

1.

6. The high-temperature resistant current collector substrate film according to claim 1, characterized in that, The ratio of allylphenol, n-octylamine, paraformaldehyde, and 1,4-dioxane was 1.34 g:(1.21-1.37) g:(0.6-0.8) g:(40-60) mL; the ratio of allyl-functionalized benzoxazine, m-chloroperoxybenzoic acid, and dichloromethane was 1.67 g:(0.96-1.15) g:(40-60) mL.

7. The high-temperature resistant current collector substrate film according to claim 1, characterized in that, The preparation method of the high-temperature resistant modifier includes: Weigh out o-aminobenzenesulfonamide and add it to toluene. Stir well under nitrogen protection and heat to 75-85℃. Gradually add epoxy-functionalized benzoxazine and continue stirring until well mixed. Then add catalyst and keep warm and stir for 8-10 hours. After the reaction is complete, wash with water, rotary evaporate and vacuum dry in sequence to obtain high temperature resistant modifier.

8. The high-temperature resistant current collector substrate film according to claim 1, characterized in that, The ratio of epoxy-functionalized benzoxazine, o-aminobenzenesulfonamide and toluene is 1g:(0.23-0.38)g:(5-15)mL; the catalyst is triethylamine, and the amount added is 0.8%-1.6% of the mass of epoxy-functionalized benzoxazine.

9. A method for preparing a high-temperature resistant current collector substrate film according to claim 1, characterized in that, Includes the following steps: Step 1: Vacuum-dried PET resin, high-temperature resistant modifier, nano-inorganic filler, lubricant, stabilizer, nucleating agent and antioxidant are added to a high-speed mixer in the proportion of parts by weight and mixed thoroughly to obtain a premix. Step 2: The premixed material is fed into a twin-screw extruder, melt-blended, extruded, cooled, and pelletized to obtain composite masterbatch; Step 3: After drying the composite masterbatch, it is fed into a single-screw extrusion casting machine and formed into a casting sheet on a cooling roller. The casting sheet is then biaxially stretched and wound up to obtain a high-temperature resistant current collector base film.

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