Method for improving temperature resistance and wetting performance of pe separator, pe separator and application

Abstract

The application discloses a method for improving temperature resistance and infiltration performance of PE diaphragm, a PE diaphragm and application, and belongs to the technical field of PE diaphragm modification. The method comprises the following steps in sequence: making PE diaphragm and F2-N2 mixed gas containing 0.1-1 v / v% F2 to have a gas-solid phase reaction, and making the obtained fluorinated product and F2-O2-N2 mixed gas containing 3 v / v% O2 and 1% v / v F2 to have a gas-solid phase reaction, so that the PE diaphragm with improved temperature resistance and infiltration performance is obtained. The temperature resistance and infiltration performance of the PE diaphragm can be significantly improved by making the PE diaphragm have two gas-solid phase reactions, and the method has the characteristics of simple process, simple operation, low cost and good commercial application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of PE diaphragm modification, and particularly relates to a method for improving temperature resistance and wetting performance of a PE diaphragm, a PE diaphragm and application. BACKGROUND

[0002] PE (polyethylene) film has excellent electrochemical stability, high mechanical strength and low cost, and has shown good commercial application in Li + battery diaphragm applications. However, when using PE film to prepare Li + battery diaphragm, the poor wetting performance, poor retention capacity and low temperature resistance of the PE film greatly limit the application of Li + batteries in high-performance batteries. Therefore, in order to meet the related applications of high-performance Li + batteries, it is necessary to improve the wetting performance and temperature resistance of the PE film.

[0003] The patent document with publication number CN 112332023 A discloses a kind of ultra-thin high-strength modified lithium ion battery diaphragm and its preparation method, which discloses that after microporous diaphragm occurs fluorination in F2-N2 mixed atmosphere and microwave grafting in polyvinyl alcohol solution, the wetting performance, liquid retention capacity and heat resistance of the diaphragm are obviously improved.

[0004] However, this technology has the following problems in industrial application: first, the process flow is long, the operability is poor, and the cost is high; second, the fluorinated microporous diaphragm needs to be immersed in polyvinyl alcohol to perform solid-liquid irradiation grafting, which increases the related costs of irradiation, cleaning and drying, greatly limiting commercial application. SUMMARY

[0005] The application discloses a method for improving the temperature resistance and wetting performance of a PE diaphragm, a PE diaphragm and application, which can significantly improve the wetting performance, liquid retention capacity and heat resistance of the PE diaphragm by sequentially subjecting the PE diaphragm to gas-solid phase reaction in a F2-N2 mixed atmosphere containing 0.1-1% F2 and an O2-N2 mixed atmosphere containing 3% O2, effectively solving the problems of long process flow, complicated operation and high cost of the above method.

[0006] In order to achieve the above purpose, the technical scheme of the application is:

[0007] The first aspect of the application provides a method for improving the temperature resistance and wetting performance of a PE diaphragm, characterized in that the method comprises the following steps:

[0008] subjecting the PE diaphragm to gas-solid phase reaction with F2-N2 mixed gas containing 0.1-1v / v% F2 to obtain a fluorination product;

[0009] The fluorination product is subjected to a gas-solid phase reaction with F2-N2 mixed gas containing 0.1-1 v / v% F2 to obtain a fluorination product.

[0010] In combination with the first aspect, preferably, the method comprises:

[0011] The PE diaphragm is placed in the reaction kettle, and after air replacement by introducing N2 into the reaction kettle, vacuum is drawn;

[0012] The reaction kettle is subjected to a gas-solid phase reaction by introducing F2-N2 mixed gas containing 0.1-1 v / v% F2 to obtain a fluorination product;

[0013] After vacuum is drawn, the reaction kettle is subjected to a gas-solid phase reaction by introducing F2-O2-N2 mixed gas containing 3 v / v% O2 and 1% v / v F2 to obtain an oxyfluorination product.

[0014] In combination with the first aspect, preferably, after obtaining the oxyfluorination product, the method further comprises:

[0015] F2 is replaced by introducing N2 into the reaction kettle.

[0016] In combination with the first aspect, preferably, after vacuum is drawn, the pressure in the reaction kettle is less than 100 Pa.

[0017] In combination with the first aspect, preferably, after introducing the F2-N2 mixed gas containing 0.1-1 v / v% F2, the pressure in the reaction kettle is 5-20 KPa;

[0018] and / or,

[0019] After introducing the F2-O2-N2 mixed gas containing 3 v / v% O2 and 1% v / v F2, the pressure in the reaction kettle is 5-20 KPa.

[0020] In combination with the first aspect, preferably, the introduction rate of the F2-N2 mixed gas containing 0.1-1 v / v% F2 is 0.1-5 L / min;

[0021] and / or,

[0022] The introduction rate of the F2-O2-N2 mixed gas containing 3 v / v% O2 and 1% v / v F2 is 0.1-5 L / min.

[0023] In combination with the first aspect, preferably, the temperature of the two gas-solid phase reactions is 0-50°C, and the time is 5-20 min.

[0024] In combination with the first aspect, preferably, the temperature of the two gas-solid phase reactions is 10-20°C, and the time is 10-20 min.

[0025] The second aspect of the present application provides the PE separator modified by the method of the first aspect.

[0026] The third aspect of the present application provides the PE separator of the second aspect for manufacturing Li + application in a battery separator.

[0027] Compared with the prior art, the advantages or beneficial effects of the present application at least include:

[0028] The modification method disclosed in the present application can form a large number of free radicals and COOH on the surface of the PE separator by the technical concept of combining fluorination with oxyfluorination, wherein the free radicals have the characteristics of micro-crosslinking reaction, thereby effectively improving the modulus and temperature resistance of the PE separator; the polar group COOH can endow the surface of the PE separator with excellent hydrophilic performance, thereby effectively improving the wetting performance of the PE separator. Meanwhile, on the basis of the combination of fluorination and oxyfluorination, by controlling the volume concentration of the effective gas, the generation of C-F2 and CF3 bonds on the surface of the PE separator is effectively reduced under the premise of effectively generating free radicals and COOH, which prevents the formation of a structure similar to tetrafluoroethylene on the surface of the PE separator and is conducive to further improving the wetting performance of the PE separator; in addition, the method of the present application can endow the PE separator with excellent temperature resistance and wetting performance by two-step gas-solid phase reaction, which is simple in process, easy to operate, low in cost, and has good commercial application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and for those skilled in the art, other drawings can also be obtained on the basis of these drawings without creating labor.

[0030] Figure 1 ATR-FTIR spectrum of the original PE separator and the modified separator PE-1 provided for the embodiments of the present application;

[0031] Figure 2 Hydrophilic performance test results of the original PE separator and the modified separator PE-1 provided for the embodiments of the present application;

[0032] Figure 3 Temperature resistance test results of the original PE separator and the modified separator PE-1 provided for the embodiments of the present application. DETAILED DESCRIPTION

[0033] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of the present application.

[0034] In the following description of the embodiments of the present application, the term "and / or" is used to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the cases of A existing alone, B existing alone and A and B existing simultaneously. Wherein A and B can be singular or plural. The character " / " generally represents that the associated objects before and after it are in an "or" relationship.

[0035] In the following description of the embodiments of the present application, the term "at least one" means one or more, and "multiple" means two or more. "At least one of the following (one)" or similar expressions means any combination of these items, including any combination of single (one) or multiple items. For example, "at least one of a, b or c", or "at least one of a, b and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b and c can be single or multiple.

[0036] Those skilled in the art should understand that in the following description of the embodiments of the present application, the order of the serial numbers does not mean the order of execution, and some or all steps can be executed in parallel or in sequence, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0037] The terms used in the embodiments of the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0038] In a first aspect, the embodiments of the present application specifically provide a modification method for improving the temperature resistance and wetting performance of PE separator, the modification method of the embodiments of the present application comprises:

[0039] The PE separator is subjected to gas-solid phase reaction with F2-N2 mixed gas containing 0.1-1v / v% F2 to obtain a fluorinated product;

[0040] The fluorinated product is subjected to gas-solid phase reaction with F2-O2-N2 mixed gas containing 3v / v% O2 and 1% v / v F2 to obtain an oxyfluorinated product.

[0041] PE separator is understood in the general sense of the art, specifically Li + The PE separator for battery can be purchased from the market or synthesized by the method well known in the art, and the specific source and performance of the PE separator are not particularly limited in the embodiments of the application. Any commercially available PE separator in the art can be used.

[0042] The modification method of the embodiments of the application can significantly improve the temperature resistance and wettability of the PE separator by performing two-stage gas-solid phase reactions. In the first stage, fluorination modification is performed by introducing a small amount of fluorine gas. On the one hand, free radicals are formed on the surface of the PE separator by grafting, and the free radicals can undergo micro-crosslinking reactions, thereby effectively improving the modulus and temperature resistance of the PE separator. On the other hand, the generation of C-F2 and CF3 bonds on the surface of the PE separator can be effectively reduced, thereby effectively preventing the formation of a tetrafluoroethylene-like structure on the surface of the PE separator, which is conducive to further improving the wettability of the PE separator. In the second stage, oxyfluorination modification is performed by introducing oxygen and fluorine gas. Oxygen groups are grafted onto the surface of the PE separator to form polar groups COOH by using fluorine gas to initiate oxygen, thereby imparting good hydrophilic properties to the surface of the PE separator, and thus improving the wettability of the PE separator. Therefore, the technical concept of combining fluorination modification and oxyfluorination modification in the embodiments of the application effectively improves the temperature resistance and wettability of the PE separator, and the modification method has the advantages of simple process, easy operation, low cost, and good commercial application prospect.

[0043] The embodiments of the application provide a specific scheme for implementing the modification method, specifically as follows:

[0044] The PE separator is placed in a reaction kettle, and N2 is introduced into the reaction kettle to replace the air in the kettle, and then vacuum is applied.

[0045] F2-N2 mixed gas containing 0.1-1v / v% F2 is introduced into the reaction kettle to perform a gas-solid phase reaction, and a fluorination product is obtained.

[0046] After vacuum is applied, F2-O2-N2 mixed gas containing 3v / v% O2 and 1% v / v F2 is introduced into the reaction kettle to perform a gas-solid phase reaction, and an oxyfluorination product is obtained.

[0047] In the embodiments of the application, N2 is first introduced into the reaction kettle to replace the air in the kettle before the specific implementation, thereby effectively avoiding the interference of residual air in the subsequent fluorination and oxyfluorination processes on the gas-solid phase reaction, making the fluorination and oxyfluorination modification more effective and efficient.

[0048] In the modification method of the embodiments of the application, after the oxyfluorination product is obtained, the method further includes:

[0049] The reaction kettle is connected with N2 to replace F2 sufficiently, so that the reaction kettle does not contain F2 residue, which not only ensures the safety of subsequent operation, but also F2 can be recycled for multiple uses, which meets the environmental protection requirements and reduces the cost.

[0050] In specific embodiments, the pressure in the reaction kettle after vacuumizing is preferably less than 100 Pa. Controlling the pressure in the kettle to be less than 100 Pa can effectively ensure better vacuum degree in the kettle, which is beneficial to improve the efficiency of gas-solid phase reaction.

[0051] In specific embodiments, the pressure in the reaction kettle after the F2-N2 mixed gas containing 0.1-1 v / v% F2 is introduced is 5-20 KPa; and / or, the pressure in the reaction kettle after the F2-O2-N2 mixed gas containing 3 v / v% O2 and 1% v / v F2 is introduced is 5-20 KPa, which can effectively improve the efficiency of the two gas-solid phase reactions. The pressure in the reaction kettle can be any value in the range of 5-20 KPa, which can be preferably 10 KPa, 20 KPa, etc.

[0052] In specific embodiments, the introduction rate of the F2-N2 mixed gas containing 0.1-1 v / v% F2 is 0.1-5 L / min; and / or, the introduction rate of the F2-O2-N2 mixed gas containing 3 v / v% O2 and 1% v / v F2 is 0.1-5 L / min, which is beneficial to improve the effect of each gas-solid phase reaction, so that the efficiency of gas-solid phase reaction is higher. The introduction rate of the two mixed gases can be any value in the range of 0.1-5 L / min, which is preferably 0.1 L / min, 0.2 L / min, 0.3 L / min, 0.4 L / min, 0.5 L / min, 1 L / min, 1.5 L / min, 2 L / min, 2.5 L / min, 3 L / min, 3.5 L / min, 4.0 L / min, 4.5 L / min and 5 L / min, etc.

[0053] In specific embodiments, the temperature of the two gas-solid phase reactions is preferably 0-50℃, and the time is preferably 5-20 min, which can improve the reaction efficiency of gas-solid phase reaction and save time. The temperature can be any value in the range of 0-50℃, which is preferably 10℃, 20℃, etc.

[0054] In a second aspect, the embodiments of the present application also provide a PE separator modified by the method of the first aspect. The surface and pore wall of the PE separator are grafted with free radicals and polar groups COOH by the modification method of the embodiments of the present application. Therefore, the PE separator modified by the method has excellent hydrophilic performance and temperature resistance.

[0055] In a third aspect, based on the excellent hydrophilic property and temperature resistance of the PE separator according to the embodiments of the present application, the embodiments of the present application provide an application of the PE separator described above. Specifically, the PE separator according to the embodiments of the present application is used to manufacture Li + The battery separator. Wherein, based on the performance characteristics of the PE separator according to the embodiments of the present application, the PE separator according to the embodiments of the present application is used as a Li + The battery separator, on the one hand, can improve the wettability of the PE separator and the electrolyte, and increase the liquid absorption rate of the PE separator and the electrolyte retention rate, thereby being conducive to improving the electrical conductivity and the Li + The number of Li + The battery migration, so as to improve the electrical performance of the Li + The battery; on the other hand, it can improve the protection ability of the PE separator to the battery at a higher temperature, so as to improve the safety performance of the Li + The battery.

[0056] The present application will be further described in detail below in combination with specific embodiments.

[0057] Embodiment 1

[0058] The present embodiment provides a method for improving the temperature resistance and wettability of the PE separator, which comprises steps S101-S104 in sequence:

[0059] S101: After the PE separator is put into the reaction kettle, N2 is introduced into the reaction kettle for air replacement for 3 times, and the pressure in the reaction kettle is less than 100 Pa;

[0060] S102: F2-N2 mixed gas containing 1v / v% F2 is introduced into the reaction kettle, the flow rate of the introduced gas is 3L / min, and the pressure in the reaction kettle is 20KPa, then gas-solid phase reaction is carried out at a temperature of 10℃ for 20min to obtain a fluorinated product;

[0061] S103: N2 is introduced into the reaction kettle for air replacement for 3 times, and the pressure in the reaction kettle is less than 100 Pa, then F2-O2-N2 mixed gas containing 3v / v% O2 and 1% v / v F2 is introduced into the reaction kettle, the flow rate of the introduced gas is 3L / min, and the pressure in the reaction kettle is 20KPa, then gas-solid phase reaction is carried out at a temperature of 10℃ for 30min to obtain an oxyfluorinated product;

[0062] S104: N2 is introduced into the reaction kettle for sufficient F2 replacement, and after the F2 in the reaction kettle is completely replaced and recovered, the oxyfluorinated product is taken out from the reaction kettle, which is the modified separator PE-1.

[0063] In order to verify the success of the modified PE separator according to the embodiments of the present application, the original PE separator and the modified separator PE-1 are subjected to ATR-FTIR spectral characterization, and the results areFigure 1 The ATR-FTIR spectra of the original PE separator and the modified separator PE-1 are shown. Among them, Figure 1 The ATR-FTIR spectra of the original PE separator and the modified separator PE-1 are shown. Among them,

[0064] According to Figure 1 It can be seen that the modified separator PE-1 has C-F absorption peaks at 1000-1300 cm -1 and C=O absorption peaks at 1650-1750 cm -1 , indicating that the C-F and COOH groups are successfully grafted on the PE separator modified in the application; and the original PE separator has no C-F and C=O absorption peaks.

[0065] Example 2

[0066] The method for improving the temperature resistance and wettability of the PE separator comprises steps S201-S204 in sequence:

[0067] S201: After the PE separator is put into the reaction kettle, N2 is introduced into the reaction kettle for air replacement for 3 times, and the pressure in the reaction kettle is less than 100 Pa;

[0068] S202: After the F2-N2 mixed gas containing 0.1v / v% F2 is introduced into the reaction kettle and the pressure in the reaction kettle is 10 KPa, the gas-solid phase reaction is carried out at 20℃ for 20 min to obtain a fluorinated product;

[0069] S203: After N2 is introduced into the reaction kettle for air replacement for 3 times and the pressure in the reaction kettle is less than 100 Pa, the F2-O2-N2 mixed gas containing 3v / v% O2 and 1% v / v F2 is introduced into the reaction kettle, and the pressure in the reaction kettle is 20 KPa, and the gas-solid phase reaction is carried out at 20℃ for 30 min to obtain an oxyfluorinated product;

[0070] S204: After N2 is introduced into the reaction kettle for sufficient F2 replacement, the oxyfluorinated product is taken out from the reaction kettle after the F2 in the reaction kettle is completely replaced and recovered, which is the modified separator PE-2.

[0071] Example 3

[0072] The method for improving the temperature resistance and wettability of the PE separator comprises steps S301-S304 in sequence:

[0073] S301: After the PE separator is put into the reaction kettle, N2 is introduced into the reaction kettle for air replacement for 3 times, and the pressure in the reaction kettle is less than 100 Pa;

[0074] S302: After the F2-N2 mixed gas containing 0.5v / v% F2 is introduced into the reactor and the pressure in the reactor is 20KPa, the gas-solid phase reaction is carried out at 10℃ for 20min to obtain the fluorinated product;

[0075] S303: After the N2 is introduced into the reactor for 3 times of air replacement and the pressure in the reactor is less than 100Pa, the F2-O2-N2 mixed gas containing 3v / v% O2 and 1% v / v F2 is introduced into the reactor, and the pressure in the reactor is 20KPa, and then the gas-solid phase reaction is carried out at 10℃ for 30min to obtain the oxyfluorinated product;

[0076] S304: After the N2 is introduced into the reactor for sufficient F2 replacement, the oxyfluorinated product is taken out from the reactor after the F2 in the reactor is completely replaced, which is the modified membrane PE-3.

[0077] To verify the actual effect of the modification method of examples 1-3, the present application provides further analysis and explanation of comparative examples 1-10.

[0078] Comparative example 1

[0079] The present comparative example provides a modification method, which comprises the steps of:

[0080] S401: After the PE membrane is put into the reactor, the N2 is introduced into the reactor for 3 times of air replacement, and the pressure in the reactor is less than 100Pa;

[0081] S402: The F2-N2 mixed gas containing 1v / v% F2 is introduced into the reactor, and the gas-solid phase reaction is carried out at the conditions of 10KPa pressure and 10℃ temperature for 20min, which is the membrane PE-4.

[0082] Comparative example 2

[0083] The present comparative example 2 provides a modification method, which comprises the steps of:

[0084] S401: After the PE membrane is put into the reactor, the N2 is introduced into the reactor for 3 times of air replacement, and the pressure in the reactor is less than 100Pa;

[0085] S402: The F2-N2 mixed gas containing 1v / v% F2 is introduced into the reactor, and the gas-solid phase reaction is carried out at the conditions of 10KPa pressure and 20℃ temperature for 20min, which is the membrane PE-5.

[0086] Comparative example 3

[0087] The present comparative example 3 provides a modification method, which comprises the steps of:

[0088] S401: After the PE membrane was put into the reactor, N2 was introduced into the reactor to replace air for 3 times, and the pressure in the reactor was less than 100 Pa;

[0089] S402: F2-N2 mixed gas containing 1v / v% F2 was introduced into the reactor, and the pressure in the reactor was 20 KPa and the temperature was 10°C, and the gas-solid phase reaction was carried out for 10 min, which was the membrane PE-6.

[0090] Comparative Example 4

[0091] Comparative Example 4 provides a modification method, which comprises the steps of:

[0092] S401: After the PE membrane was put into the reactor, N2 was introduced into the reactor to replace air for 3 times, and the pressure in the reactor was less than 100 Pa;

[0093] S402: F2-N2 mixed gas containing 1v / v% F2 was introduced into the reactor, and the pressure in the reactor was 10 KPa and the temperature was 20°C, and the gas-solid phase reaction was carried out for 30 min, which was the membrane PE-7.

[0094] Comparative Example 5

[0095] Comparative Example 5 provides a modification method, which comprises the steps of:

[0096] S401: After the PE membrane was put into the reactor, N2 was introduced into the reactor to replace air for 3 times, and the pressure in the reactor was less than 100 Pa;

[0097] S402: F2-N2 mixed gas containing 1v / v% F2 was introduced into the reactor, and the pressure in the reactor was 10 KPa and the temperature was 20°C, and the gas-solid phase reaction was carried out for 30 min, which was the membrane PE-7.

[0098] Comparative Example 6

[0099] Comparative Example 6 provides a modification method, which comprises the steps of:

[0100] S401: After the PE membrane was put into the reactor, N2 was introduced into the reactor to replace air for 3 times, and the pressure in the reactor was less than 100 Pa;

[0101] S402: F2-N2 mixed gas containing 1v / v% F2 was introduced into the reactor, and the pressure in the reactor was 20 KPa and the temperature was 30°C, and the gas-solid phase reaction was carried out for 20 min, which was the membrane PE-9.

[0102] Comparative Example 7

[0103] Comparative Example 7 provides a modification method, which comprises the steps of:

[0104] S401: After the PE membrane is put into the reaction kettle, N2 is introduced into the reaction kettle for air replacement for 3 times, and the pressure in the reaction kettle is less than 100 Pa;

[0105] S402: F2-N2 mixed gas containing 1 v / v% F2 is introduced into the reaction kettle, and the pressure in the reaction kettle is 20 KPa and the temperature is 10°C, and the gas-solid phase reaction is carried out for 5 min, which is the membrane PE-10.

[0106] Comparative Example 8

[0107] Comparative Example 8 provides a modification method, which comprises the steps of:

[0108] S401: After the PE membrane is put into the reaction kettle, N2 is introduced into the reaction kettle for air replacement for 3 times, and the pressure in the reaction kettle is less than 100 Pa;

[0109] S402: F2-N2 mixed gas containing 0.1 v / v% F2 is introduced into the reaction kettle, and the pressure in the reaction kettle is 20 KPa and the temperature is 10°C, and the gas-solid phase reaction is carried out for 20 min, which is the membrane PE-11.

[0110] Comparative Example 9

[0111] Comparative Example 9 provides a modification method, which comprises the steps of:

[0112] S401: After the PE membrane is put into the reaction kettle, N2 is introduced into the reaction kettle for air replacement for 3 times, and the pressure in the reaction kettle is less than 100 Pa;

[0113] S402: F2-N2 mixed gas containing 0.5 v / v% F2 is introduced into the reaction kettle, and the pressure in the reaction kettle is 20 KPa and the temperature is 10°C, and the gas-solid phase reaction is carried out for 20 min, which is the membrane PE-12.

[0114] Comparative Example 10

[0115] Comparative Example 10 provides a modification method, which comprises the steps of:

[0116] S401: After the PE membrane is put into the reaction kettle, N2 is introduced into the reaction kettle for air replacement for 3 times, and the pressure in the reaction kettle is less than 100 Pa;

[0117] S402: After putting the PE membrane into the reactor, N2 was introduced into the reactor for air replacement for 3 times, and the pressure in the reactor was less than 100 Pa; F2-N2 mixed gas containing 0.1 v / v% F2 was introduced into the reactor, and the gas-solid phase reaction was carried out under the condition that the pressure in the reactor was 5 KPa and the temperature was 20°C for 20 min, to obtain the membrane PE-12.

[0118] Comparative Example 11

[0119] The comparative example 11 provides a modification method, which comprises the steps of:

[0120] S501: After putting the PE membrane into the reactor, N2 was introduced into the reactor for air replacement for 3 times, and the pressure in the reactor was less than 100 Pa;

[0121] S502: N2 was introduced into the reactor, and the pressure in the reactor was 20 KPa; the gas-solid phase reaction was carried out at 10°C for 20 min to obtain the fluorinated product;

[0122] S503: After N2 was introduced into the reactor for air replacement for 3 times, and the pressure in the reactor was less than 100 Pa, O2-N2 mixed gas containing 3 v / v% O2 was introduced into the reactor, and the gas-solid phase reaction was carried out under the condition that the pressure in the reactor was 20 KPa and the temperature was 10°C for 30 min to obtain the oxyfluorinated product;

[0123] S504: N2 was introduced into the reactor for sufficient F2 replacement, and after the F2 in the reactor was completely replaced and recovered, the oxyfluorinated product was taken out from the reactor, to obtain the modified membrane PE-13.

[0124] Comparative Example 12

[0125] The comparative example 12 provides a modification method, which comprises the steps of:

[0126] S501: After putting the PE membrane into the reactor, N2 was introduced into the reactor for air replacement for 3 times, and the pressure in the reactor was less than 100 Pa;

[0127] S502: N2 was introduced into the reactor, and the pressure in the reactor was 20 KPa; the gas-solid phase reaction was carried out at 10°C for 20 min to obtain the fluorinated product;

[0128] S503: After N2 was introduced into the reactor for air replacement for 3 times, and the pressure in the reactor was less than 100 Pa, F2-O2-N2 mixed gas containing 3 v / v% O2 and 1% v / v F2 was introduced into the reactor, and the gas-solid phase reaction was carried out under the condition that the pressure in the reactor was 20 KPa and the temperature was 10°C for 20 min to obtain the oxyfluorinated product;

[0129] S504: N2 is introduced into the reactor to replace F2 completely, and then the oxygenated product is taken out from the reactor, which is the modified membrane PE-14.

[0130] The hydrophilic property and heat resistance of the membranes PE-1 to PE-14 prepared in Examples 1-3 and Comparative Examples 1-12 are tested, and the results are shown in Table 1.

[0131] Table 1-Test results of hydrophilic property and heat resistance of PE membranes

[0132]

[0133]

[0134] As shown in Table 1, the combination of fluorination and oxyfluorination can effectively improve the heat resistance and hydrophilic property of PE membranes, and by controlling the volume concentration of effective gas, the wettability of PE membranes can be further improved.

[0135] wherein, Figure 2 The hydrophilic property of the original PE membrane and the modified membrane PE-1 is tested, and the results are shown in Table 1. Figure 3 The heat resistance of the original PE membrane and the modified membrane PE-1 is tested, and the results are shown in Table 1.

[0136] According to Figures 2-3 It can be confirmed that the modification of the PE membrane according to the examples of the present application effectively improves the heat resistance and hydrophilic property of the PE membrane.

[0137] Each embodiment in the specification is described in a progressive manner, and the same or similar parts between each embodiment can be referred to each other, and each embodiment mainly explains the difference from other embodiments.

[0138] The above examples are only used to illustrate the technical solutions of the present application, and are not limited to the present application; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A method for improving the temperature resistance and wetting properties of PE separators, characterized in that, The method includes: After placing the PE diaphragm into the reactor and purging it with N2 to replace the air, a vacuum is drawn to ensure that the pressure inside the reactor is less than 100 Pa. A gas-solid phase reaction is carried out by introducing an F2-N2 mixture containing 0.1-1 v / v% F2 into the reaction vessel to obtain a fluorinated product. The pressure inside the reaction vessel after introducing the F2-N2 mixture containing 0.1-1 v / v% F2 is 20 kPa, the temperature of the gas-solid phase reaction is 10-20 °C, and the time is 20 min. Then, after evacuation, a gas-solid phase reaction is carried out in the reactor containing 3v / v% O2 and 1%v / v F2 to obtain an oxygen fluorination product. The pressure inside the reactor after the gas-solid phase reaction is carried out is 20 kPa, the temperature of the gas-solid phase reaction is 10-20 °C, and the time is 30 min.

2. The method according to claim 1, characterized in that, After obtaining the oxyfluorinated product, the method further includes: N2 is introduced into the reactor to replace the mixed gas.

3. The method according to claim 1, characterized in that, The F2-N2 mixture containing 0.1-1 v / v% F2 is introduced at a rate of 0.1-5 L / min; And / or, the F2-O2-N2 mixture containing 3v / v% O2 and 1%v / v F2 is introduced at a rate of 0.1-5 L / min.

4. A PE separator modified according to any one of claims 1-3.

5. A PE separator according to claim 4 in the manufacture of Li + Applications in battery separators.

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