CN112194935A - PVDF (polyvinylidene fluoride) slurry, diaphragm and preparation method thereof - Google Patents
PVDF (polyvinylidene fluoride) slurry, diaphragm and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
- C08J7/04—Coating
- C08J7/0427—Coating with only one layer of a composition containing a polymer binder
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1067—Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1067—Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound
- C08G73/1071—Wholly aromatic polyimides containing oxygen in the form of ether bonds in the main chain
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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- C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
- C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
- C08J2323/04—Homopolymers or copolymers of ethene
- C08J2323/06—Polyethene
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2427/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
- C08J2427/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
- C08J2427/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
- C08J2427/16—Homopolymers or copolymers of vinylidene fluoride
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2479/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2461/00 - C08J2477/00
- C08J2479/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
- C08J2479/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses PVDF slurry, a diaphragm and a preparation method thereof, wherein the preparation method of the PVDF slurry comprises the following steps: preparing a first slurry and a second slurry, uniformly mixing the first slurry and the second slurry, adding dimethyl carbonate, uniformly mixing, adding tripropylene glycol to obtain a PVDF slurry, wherein the preparation method of the first slurry comprises the following steps: cooling N-methyl pyrrolidone to 7-12 ℃, mixing with the first liquid, adding the second liquid, adjusting the temperature to 15-20 ℃, and stirring to perform an exothermic reaction; the preparation method of the second slurry comprises the following steps: and uniformly mixing the PVDF powder with N-methyl pyrrolidone so as to completely dissolve the PVDF powder in the N-methyl pyrrolidone. According to the invention, through synthesizing polyamic acid as first slurry and then adding dissolved PVDF, the polyamic acid is dehydrated at high temperature and then converted into polyimide, and the polyimide and the PVDF generate hydrogen bonds to generate the high-temperature resistant PVDF.
Description
Technical Field
The invention belongs to the technical field of battery diaphragms, and particularly relates to PVDF slurry, a diaphragm and a preparation method thereof.
Background
The oily PVDF is mainly used for bonding a battery pole piece in a lithium battery to improve the bonding force between a diaphragm and the pole piece, but the PVDF does not have the high temperature resistance, so that the thermal shrinkage performance of the diaphragm is poor, and the safety performance of the lithium battery is not favorable. The whole process is time-consuming and labor-consuming, and the process is relatively complex.
Disclosure of Invention
In order to improve the thermal stability of the PVDF coating diaphragm, the invention aims to provide a preparation method of PVDF slurry, and the preparation method can improve the thermal shrinkage performance of the diaphragm and retain the function of PVDF in a lithium battery for bonding a pole piece by applying polyimide to the PVDF slurry.
Another object of the present invention is to provide a PVDF slurry obtained by the above-mentioned preparation method.
It is another object of the present invention to provide a separator prepared based on the above-described PVDF slurry.
The purpose of the invention is realized by the following technical scheme.
A preparation method of PVDF slurry comprises the following steps:
step 1, preparing a first slurry and a second slurry, wherein,
the preparation method of the first slurry comprises the following steps: in an inert gas or nitrogen environment, cooling N-methyl pyrrolidone to 7-12 ℃, mixing with a first liquid, stirring for 15-20 min, adding a second liquid, adjusting the temperature to 15-20 ℃, stirring for 20-30 min, and carrying out an exothermic reaction to obtain a first slurry, wherein the first liquid is p-phenylenediamine or 4.4 diaminodimethyl ether, the second liquid is pyromellitic dianhydride or 3.3.4.4 biphenyl tetracarboxylic dianhydride, and the mass sum of the first liquid and the second liquid and the ratio of the N-methyl pyrrolidone are (5-10): (90-95), wherein the ratio of the first liquid to the second liquid is (1-4) in parts by weight: (2-3);
the preparation method of the second slurry comprises the following steps: uniformly mixing PVDF powder and N-methyl pyrrolidone to completely dissolve the PVDF powder in the N-methyl pyrrolidone to obtain a second slurry, wherein the mass part ratio of the PVDF powder to the N-methyl pyrrolidone is (5-10): (90-95);
in the step 1, the first liquid is p-phenylenediamine, the second liquid is pyromellitic dianhydride, and the ratio of the first liquid to the second liquid is (1-5) to (2-10) according to the parts by weight of the substances.
In the step 1, the first liquid is 4.4 diaminodimethyl ether, the second liquid is pyromellitic dianhydride, and the ratio of the first liquid to the second liquid is (1.5-4) to (2-8) in parts by weight.
In the step 1, the first liquid is p-phenylenediamine, the second liquid is 3.3.4.4 biphenyl tetracarboxylic dianhydride, and the ratio of the first liquid to the second liquid is (4-8) to (3-6) according to the parts by weight of the materials.
In the step 1, in the preparation method of the second slurry, the PVDF powder and the N-methylpyrrolidone are uniformly mixed by stirring for 60-90 min.
In the step 1, the exothermic reaction is carried out so that the system temperature of the exothermic reaction is maintained at 15 to 20 ℃.
Step 2, mixing the first slurry and the second slurry, stirring for 30-50 min, adding dimethyl carbonate, stirring for 30-50 min, adding tripropylene glycol, and stirring for 30-50 min to obtain the PVDF slurry, wherein the ratio of the first slurry to the second slurry to the dimethyl carbonate to the tripropylene glycol is (20-30) in parts by mass: (45-50): (5-25): (10-15).
PVDF slurry obtained by the preparation method.
The PVDF slurry is coated on a base film, extracted, cured, dried and rolled to obtain the diaphragm, wherein the coating thickness is 1-2 microns.
In the above technical scheme, the base film is a polyethylene base film.
The invention mainly synthesizes polyamide acid as first slurry, then adds dissolved PVDF, makes polyamide acid dehydrated at high temperature and converted into polyimide, makes polyimide and PVDF generate hydrogen bond, forms special structure of polyimide and polyvinylidene fluoride, and generates high temperature resistant PVDF. The tripropylene glycol plays a main role in the scheme of the invention in curing the surface coating of the diaphragm during extraction, the tripropylene glycol is dissolved in water to leave gaps on the diaphragm, the tripropylene glycol is a water-washing pore-forming agent of the diaphragm, and the dimethyl carbonate is mainly a gas-phase pore-forming agent during drying.
Drawings
FIG. 1 is an SEM of the separator of example 1.
Detailed Description
The technical scheme of the invention is further explained by combining specific examples.
The relevant instrumentation used in the specific embodiment of the invention is as follows:
a double planetary mixer, model HY-DLH43L, Guangzhou Hongshang mechanical science and technology Co., Ltd;
germany Mahr Mark full-automatic film thickness gauge, model C1216M-AT;
asahi Seiko Asahi Fine air permeameter, model EG01-55-1 MR;
film thermal shrinkage performance tester, model C631H
The relevant drugs used in the embodiments of the present invention are as follows:
n methyl pyrrolidone with purity of 99.5%, Ci Sus chemical reagent manufacturing Co., Ltd, Tianjin;
dimethyl carbonate with a purity of 99.5%, manufactured by sidereal chemical reagents manufacturing limited, Tianjin;
tripropylene glycol, 99.5% pure, Ci Sus fixed chemical reagents, Inc. of Tianjin;
4, 4-diamino dimethyl ether with purity of 99.5%, Nanjing blue whitening chemical Co., Ltd;
p-phenylenediamine, 99.5% pure, Nanjing blue whitening chemical Co., Ltd.
Pyromellitic dianhydride, purity 99.5%, Nanjing blue whitening chemical Co., Ltd.
3,3,4, 4-Biphenyltetracarboxylic dianhydride, purity 99.5%, Nanjing blue whitening chemical Co.
The test method is briefly described as follows:
the air permeability test method comprises the following steps: in the case of a fixed diaphragm, a certain air pressure is applied to one side of the diaphragm, and the air pressure is gradually reduced until it becomes equal to the atmospheric pressure due to the presence of the micropores in the diaphragm. The air permeability of the membrane was measured by comparing the time taken for the pressure to drop from the initial pressure to the final pressure.
Shrinkage test method: the rectangular membrane was placed in an oven and the membrane contracted to a size ratio over a specified time.
Adhesion test method: a battery pole piece with the width of 12.7mm and the length of 10cm is flatly placed on a diaphragm, the diaphragm is placed under the pressure of 60Mpa at the temperature of 80 ℃ for 10s, and then a tensile machine is used for pulling the diaphragm and the battery pole piece apart. The battery pole piece is a positive pole piece or a negative pole piece, the positive pole piece is formed by coating lithium iron phosphate on aluminum, and the negative pole piece is formed by coating graphite on copper foil.
The decomposition voltage test method comprises the following steps: the test is respectively at 0.5mol-1dm-3H2SO4With 1mol of-1dm-3Two diaphragms to be tested are inserted into the NaOH aqueous solution, and are connected with a decomposition voltage testing device, the voltage is gradually increased for electrolysis, and corresponding current values are recorded. The minimum voltage value that must be applied to continue electrolysis is referred to as the decomposition voltage of the separator under the conditions.
The closed-cell membrane rupture temperature test method comprises the following steps: diameter of cut
Sealing the round diaphragm sample in a mould filled with conductive liquid, putting the mould filled with the sample into an oven, heating at the speed of 5 ℃/min, recording the change value of internal resistance in the mould along with the temperature in the heating process, and the closed pore temperature: the initial temperature at which the internal resistance begins to rise significantly is the closed pore temperature; film breaking temperature: temperature at which the internal resistance value begins to drop significantly.
The porosity testing method comprises the following steps: 1. the membranes were stacked in 6 stacks, pulled flat, compressed and the air in the membranes was removed. Cutting the stacked diaphragm according to the cutting sample plate, and measuring the cut sample to obtain the area S of the sample;
2. measuring the thickness of the sample for 10 or 20 times, and calculating an average value B;
3. measuring the weight of the diaphragm by using an electronic balance for three times to obtain an average value M;
4. the porosity P ═ S ═ B [ (density of the separator raw material S × B-M)/(density of the separator raw material) S × B was calculated by the following company]100%, wherein the density of the raw material of the diaphragm is 930Kg/m2。
Tensile strength test method: cutting a diaphragm with the width of 15mm and the length of 150mm (the sample testing gauge length is 100mm), testing by using a microcomputer control electronic universal tensile testing machine, and then taking the average value of 5 sample tests;
(the positive pole piece and the negative pole piece are coated by adopting a compression roller, the lithium iron phosphate and the graphite are coated by NMP (N-methyl pyrrolidone), the positive pole piece and the negative pole piece are coated on two sides, the coating thickness of each side is 120 micrometers, and the positive pole piece and the negative pole piece can be used after being coated and dried in an oven.)
Example 1
A preparation method of PVDF slurry comprises the following steps:
step 1, preparing a first slurry and a second slurry, wherein,
the preparation method of the first slurry comprises the following steps: introducing nitrogen into a reaction tank, cooling the dehydrated N-methyl pyrrolidone to 7 ℃ in the reaction tank, mixing a first liquid with the dehydrated N-methyl pyrrolidone, stirring for 15min in a nitrogen environment, adding a second liquid, adjusting the temperature to 15 ℃ and stirring for 20min to obtain a first slurry, wherein the stirring process after adding the second liquid is an exothermic reaction, introducing cold water into a jacket of the reaction tank during the exothermic reaction to keep the system temperature of the exothermic reaction at 15 ℃, and the mass sum of the first liquid and the second liquid and the ratio of the N-methyl pyrrolidone are 5:95, the first liquid is p-phenylenediamine, the second liquid is pyromellitic dianhydride, and the ratio of the first liquid to the second liquid is 1:2 according to the parts by weight of the substances.
The preparation method of the second slurry comprises the following steps: uniformly mixing PVDF powder and N-methyl pyrrolidone by stirring for 60min, and completely dissolving the PVDF powder in the N-methyl pyrrolidone to obtain a second slurry, wherein the ratio of the PVDF powder to the N-methyl pyrrolidone in the preparation method of the second slurry is 7: 93;
step 2, mixing the first slurry and the second slurry, stirring for 30min, adding dimethyl carbonate, stirring for 30min, adding tripropylene glycol, and stirring for 30min to obtain the PVDF slurry, wherein the ratio of the first slurry to the second slurry to the dimethyl carbonate to the tripropylene glycol is 20: 45: 25: 10.
example 2
A preparation method of PVDF slurry comprises the following steps:
step 1, preparing a first slurry and a second slurry, wherein,
the preparation method of the first slurry comprises the following steps: introducing nitrogen into a reaction tank, cooling the N-methylpyrrolidone subjected to water removal to 10 ℃ in the reaction tank, mixing a first liquid with the N-methylpyrrolidone subjected to water removal, stirring for 18min in a nitrogen environment, adding a second liquid, adjusting the temperature to 18 ℃ and stirring for 20min to obtain a first slurry, wherein the stirring process after adding the second liquid is an exothermic reaction, introducing cold water into a jacket of the reaction tank during the exothermic reaction to keep the system temperature of the exothermic reaction at 18 ℃, and the mass sum of the first liquid and the second liquid and the ratio of the N-methylpyrrolidone are 7: 93, the first liquid is 4.4 diaminodimethyl ether, the second liquid is pyromellitic dianhydride, and the ratio of the first liquid to the second liquid is 1.5:2 according to the parts by weight of the substances.
The preparation method of the second slurry comprises the following steps: uniformly mixing PVDF powder and N-methyl pyrrolidone by stirring for 80min, and completely dissolving the PVDF powder in the N-methyl pyrrolidone to obtain a second slurry, wherein the ratio of the PVDF powder to the N-methyl pyrrolidone in the preparation method of the second slurry is 8: 92;
step 2, mixing the first slurry and the second slurry, stirring for 40min, adding dimethyl carbonate, stirring for 40min, adding tripropylene glycol, and stirring for 40min to obtain the PVDF slurry, wherein the ratio of the first slurry to the second slurry to the dimethyl carbonate to the tripropylene glycol is 25: 47: 13: 12.
example 3
A preparation method of PVDF slurry comprises the following steps:
step 1, preparing a first slurry and a second slurry, wherein,
the preparation method of the first slurry comprises the following steps: introducing nitrogen into a reaction tank, cooling the dehydrated N-methyl pyrrolidone to 12 ℃ in the reaction tank, mixing a first liquid with the dehydrated N-methyl pyrrolidone, stirring for 20min in a nitrogen environment, adding a second liquid, adjusting the temperature to 20 ℃ and stirring for 20min to obtain a first slurry, wherein the stirring process after adding the second liquid is an exothermic reaction, introducing cold water into a jacket of the reaction tank during the exothermic reaction to keep the system temperature of the exothermic reaction at 20 ℃, and the mass sum of the first liquid and the second liquid and the ratio of the N-methyl pyrrolidone are 5:95, the first liquid is p-phenylenediamine, the second liquid is 3.3.4.4 biphenyl tetracarboxylic dianhydride, and the ratio of the first liquid to the second liquid is 4:3 according to the parts by weight of the materials.
The preparation method of the second slurry comprises the following steps: uniformly mixing PVDF powder and N-methyl pyrrolidone by stirring for 90min, and completely dissolving the PVDF powder in the N-methyl pyrrolidone to obtain a second slurry, wherein the mass ratio of the PVDF powder to the N-methyl pyrrolidone in the preparation method of the second slurry is 10: 95;
step 2, mixing the first slurry and the second slurry, stirring for 50min, adding dimethyl carbonate, stirring for 50min, adding tripropylene glycol, and stirring for 50min to obtain PVDF slurry, wherein the ratio of the first slurry to the second slurry to the dimethyl carbonate to the tripropylene glycol is 30: 50: 5: 15.
comparative example 1
A method of preparing a slurry comprising: adding PVDF powder into N-methyl pyrrolidone, stirring for 90min to completely dissolve the PVDF powder, adding dimethyl carbonate, and stirring for 50min to obtain a slurry, wherein the mass part ratio of the PVDF powder to the N-methyl pyrrolidone to the dimethyl carbonate is 5:90: 5.
Comparative example 2
A method of preparing a slurry comprising:
step 1, putting PVDF powder into dimethylacetamide, stirring for 70min, revolving for 35r/min, and rotating for 1000r/min to obtain a liquid A, wherein the mass ratio of the PVDF powder to the dimethylacetamide is 5: 95.
And 2, adding boehmite into tripropylene glycol, uniformly stirring for 170min, revolving for 40r/min, and rotating for 2500r/min to obtain a liquid B, wherein the ratio of boehmite to tripropylene glycol is 33:67 in parts by weight.
And 3, stirring the liquid A and dimethyl carbonate for 30min, revolving for 35r/min, and rotating for 1000r/min to obtain a liquid C, wherein the ratio of the liquid A to the dimethyl carbonate is 90:10 in parts by weight.
And 4, mixing and stirring the liquid C and the liquid B for 30min, revolving for 35r/min, and rotating for 1000r/min to obtain slurry, wherein the ratio of the liquid C to the liquid B is 80:20 in parts by weight.
A preparation method of a diaphragm comprises the steps of coating slurry on the surface of a base film through an anilox roller, extracting, curing, drying and rolling to obtain the diaphragm, wherein the slurry is PVDF slurry obtained in examples 1-3, slurry obtained in comparative example 1 or slurry obtained in comparative example 2, the thickness of the base film is 12 micrometers, and the coating thickness is X micrometers.
The resulting separator was tested, and the test results are shown in tables 1 and 2.
The base film is a polyethylene base film, and the specification is 1000mm multiplied by 12 mu m; the specification of the anilox roller is 1150mm multiplied by 100mm multiplied by 1 mu m;
the parameters of the coating process were set as: the unwinding tension is 32N, the winding tension is 4N, the speed ratio of an anilox roller is 140%, the tension of a drying tunnel is 18N, and the extraction tension is 10N;
the extraction is carried out by the following steps: dividing the extraction tank into 10 small tanks, wherein the depth of each tank is 1m, extracting liquid in which deionized water and dimethylacetamide are mixed according to different mass ratios is arranged in the first three tanks to form a coagulating bath, the mass ratio of dimethylacetamide to water in the first tank is 3:2, the mass ratio of dimethylacetamide to water in the second tank is 1:1, the mass ratio of dimethylacetamide to water in the third tank is 2:3, and deionized water is arranged in the rest other tanks, so that a diaphragm penetrates through each tank, and the three coagulating baths and the deionized water with different concentrations are sequentially used for extraction.
TABLE 1
TABLE 2
FIG. 1 is a surface electron micrograph of example 1 showing that polyimide and PVDF are completely bonded together, the surface is flat, and the pore diameter is three-dimensional. The larger specific surface area is beneficial to improving the liquid absorption rate and the wettability of the diaphragm to the electrolyte.
The invention has been described in an illustrative manner, and it is to be understood that any simple variations, modifications or other equivalent changes which can be made by one skilled in the art without departing from the spirit of the invention fall within the scope of the invention.
Claims (10)
1. The preparation method of the PVDF slurry is characterized by comprising the following steps:
step 1, preparing a first slurry and a second slurry, wherein,
the preparation method of the first slurry comprises the following steps: in an inert gas or nitrogen environment, cooling N-methyl pyrrolidone to 7-12 ℃, mixing with a first liquid, stirring for 15-20 min, adding a second liquid, adjusting the temperature to 15-20 ℃, stirring for 20-30 min, and carrying out an exothermic reaction to obtain a first slurry, wherein the first liquid is p-phenylenediamine or 4.4 diaminodimethyl ether, the second liquid is pyromellitic dianhydride or 3.3.4.4 biphenyl tetracarboxylic dianhydride, and the mass sum of the first liquid and the second liquid and the ratio of the N-methyl pyrrolidone are (5-10): (90-95), wherein the ratio of the first liquid to the second liquid is (1-4) in parts by weight: (2-3);
the preparation method of the second slurry comprises the following steps: uniformly mixing PVDF powder and N-methyl pyrrolidone to completely dissolve the PVDF powder in the N-methyl pyrrolidone to obtain a second slurry, wherein the mass part ratio of the PVDF powder to the N-methyl pyrrolidone is (5-10): (90-95);
step 2, mixing the first slurry and the second slurry, stirring for 30-50 min, adding dimethyl carbonate, stirring for 30-50 min, adding tripropylene glycol, and stirring for 30-50 min to obtain the PVDF slurry, wherein the ratio of the first slurry to the second slurry to the dimethyl carbonate to the tripropylene glycol is (20-30) in parts by mass: (45-50): (5-25): (10-15).
2. The preparation method according to claim 1, wherein in the step 1, the first liquid is p-phenylenediamine, the second liquid is pyromellitic dianhydride, and the ratio of the first liquid to the second liquid is (1-5) to (2-10) in parts by weight.
3. The method according to claim 1, wherein in the step 1, the first liquid is 4.4 diaminodimethyl ether, the second liquid is pyromellitic dianhydride, and the ratio of the first liquid to the second liquid is (1.5-4) to (2-8) in parts by weight.
4. The preparation method according to claim 1, wherein in the step 1, the first liquid is p-phenylenediamine, the second liquid is 3.3.4.4 biphenyltetracarboxylic dianhydride, and the ratio of the first liquid to the second liquid is (4-8) to (3-6) in parts by weight.
5. The method according to any one of claims 1 to 4, wherein in the step 1, in the second slurry preparation method, the PVDF powder and the N-methylpyrrolidone are uniformly mixed by stirring for 60 to 90 minutes.
6. The production method according to claim 1, wherein in the step 1, the exothermic reaction is carried out so that a system temperature of the exothermic reaction is maintained at 15 to 20 ℃.
7. PVDF slurry obtained by the production process according to any one of claims 1 to 6.
8. A separator, characterized in that the PVDF slurry of claim 7 is coated on a base film, extracted, cured, dried and rolled to obtain the separator.
9. The separator according to claim 9, wherein the base film is a polyethylene base film.
10. The separator according to claim 9, wherein the coating thickness is 1 to 2 μm.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113136121A (en) * | 2021-04-14 | 2021-07-20 | 合肥利夫生物科技有限公司 | Bio-based diaphragm coating liquid, preparation method thereof and application thereof in lithium battery |
| CN116082894A (en) * | 2023-04-07 | 2023-05-09 | 安徽利科新材料科技有限公司 | Preparation method and device of bio-based coating slurry for improving battery diaphragm adhesion |
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