CN111725467A - Lithium-sulfur battery composite coating diaphragm and preparation method and application thereof - Google Patents
Lithium-sulfur battery composite coating diaphragm and preparation method and application thereof Download PDFInfo
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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
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- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
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Abstract
The invention discloses a lithium-sulfur battery composite coating diaphragm and a preparation method and application thereof, wherein the preparation method comprises the following steps: uniformly mixing a carbon conductor and a lithium conducting polymer to obtain a mixture A, uniformly dispersing the mixture A in a solution B to obtain a mixture C, adding polyvinylidene fluoride and polyoxyethylene alkylated ether into the mixture C, uniformly stirring to obtain first slurry, coating the first slurry on the positive electrode side of a base film to obtain a first coating film, coating a second slurry on the first coating film to form a second coating film, and drying. The preparation method of the invention adopts water and ethanol as solvents, which reduces the cost and protects the environment, so that the diaphragm has the special effects of sulfur interception and lithium conduction, and the aluminum oxide inorganic coating is coated on the basis, thereby improving the temperature resistance and the tensile strength of the battery diaphragm.
Description
Technical Field
The invention belongs to the technical field of lithium-sulfur batteries, and particularly relates to a lithium-sulfur battery composite coating diaphragm and a preparation method and application thereof.
Background
The new energy automobile is a strategic emerging industry which is changed from global energy and green transformation, and is an important direction of a new technological revolution and industrial change. The development of a power battery with high specific energy, low cost, long service life and high safety has become a bottleneck and key for the development of new energy automobiles. Lithium sulfur batteries, having theoretical energy densities as high as 2600Wh/kg, are considered to be one of the most promising current vehicle power battery systems. However, due to the problems of solvent shuttle of the S positive electrode, dendritic growth of the metal Li negative electrode, and low flash point of the ether electrolyte, the lithium-sulfur battery still faces the challenges of high safety, long service life and high specific energy which are difficult to be coordinated, and the commercialization process of the lithium-sulfur battery is severely restricted.
The traditional lithium battery diaphragm mostly adopts a microporous polyethylene or polypropylene film, however, because lithium sulfur polymers generated by charging and discharging of the lithium sulfur battery can affect the cyclicity and the coulombic efficiency of the battery through the diaphragm, the development of the diaphragm with the functions of sulfur interception and lithium conduction becomes one of important aspects for promoting the development of the lithium sulfur battery.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a preparation method of a composite coating diaphragm of a lithium-sulfur battery.
The invention also aims to obtain the lithium-sulfur battery composite coating diaphragm obtained by the preparation method, which overcomes the defects that the traditional battery diaphragm cannot inhibit the shuttle effect (the lithium-sulfur battery has low cycle efficiency and poor safety performance), and improves the high temperature resistance and tensile strength of the battery diaphragm.
Another object of the present invention is to provide the use of the above-described composite coated separator for a lithium sulfur battery for improving tensile strength.
The invention also aims to provide application of the composite coating diaphragm of the lithium-sulfur battery in improving temperature resistance.
The invention also aims to provide application of the composite coating diaphragm of the lithium-sulfur battery in sulfur-trapping and lithium-conducting.
The purpose of the invention is realized by the following technical scheme.
A preparation method of a lithium-sulfur battery composite coating diaphragm comprises the following steps:
1) uniformly mixing a carbon conductor and a lithium conducting polymer to obtain a mixture A, and uniformly dispersing the mixture A in a solution B to obtain a mixture C, wherein the ratio of the carbon conductor to the lithium conducting polymer is (1-3): (2-9), the solid content of the mixture A in the mixture C is 2-5%, the solution B is a mixture of alcohol and water, and the ratio of the alcohol to the water in the solution B is (1-2): (2-3), the carbon conductor is graphite, and the lithium conducting polymer is one or more of polyacrylic acid, sulfonated polyether sulfone and polymethyl methacrylate;
in the step 1), the graphite is graphene, natural graphite or artificial graphite.
In the step 1), the mixture a is mixed with the solution B and then stirred in a high-speed disperser for at least 3 hours to achieve uniform dispersion of the mixture a in the solution B.
2) Under the stirring condition, adding polyvinylidene fluoride and polyoxyethylene alkylated ether into the mixture C, and uniformly stirring to obtain a first slurry, wherein the polyvinylidene fluoride accounts for 3-5 wt% of the mixture A, and the polyoxyethylene alkylated ether accounts for 4.5-8 wt% of the mixture A;
3) coating the first slurry on the positive electrode side of a base film to obtain a first coating film on the base film, wherein the base film is a polypropylene film;
in the step 3), the thickness of the first coating film is 0.5 to 4 μm, preferably 1 μm.
4) Coating a second slurry on the first coating film for forming a second coating film, and drying to obtain the lithium-sulfur battery composite coating diaphragm, wherein the second slurry is obtained by the following method: uniformly mixing alumina powder and deionized water to obtain a mixture D, and then adding a binder, a dispersant, a pore-forming additive, sodium carboxymethylcellulose and polyoxyethylene alkyl ether into the mixture D to uniformly mix to obtain a second slurry, wherein the solid content of the alumina powder in the mixture D is 20-60%, the binder is 2-5 wt% of the alumina powder, the dispersant is 5-7 wt% of the alumina powder, the pore-forming additive is 3-4 wt% of the alumina powder, the sodium carboxymethylcellulose is 5-10 wt% of the alumina powder, and the polyoxyethylene alkyl ether is 5-8 wt% of the alumina powder; the binder is polyacrylate, the dispersant is organic ammonium salt, and the pore-forming additive is one or more of polyethylene glycol, lithium chloride, polyvinylpyrrolidone and sodium nitrate.
In the step 4), mixing alumina powder and deionized water, stirring for 2-3 hours in a stirrer, introducing into a sand mill, and continuously sanding for 4-5 hours to obtain the mixture D.
In the step 4), the thickness of the second coating film is 0.5 to 2 μm.
In the step 4), the polyacrylate is polyethylacrylate, and the organic ammonium salt is polyquaternium.
The lithium-sulfur battery composite coating diaphragm obtained by the preparation method.
The lithium-sulfur battery composite coating diaphragm is applied to improving the tensile strength.
In the technical scheme, the tensile strength is 1440-1470 Kg/cm2。
The lithium-sulfur battery composite coating diaphragm is applied to improving the temperature resistance.
In the technical scheme, the heat shrinkage rate of the alloy is 1.3-1.6% at 130 ℃ for 1 hour.
The composite coating diaphragm of the lithium-sulfur battery is applied to sulfur interception and lithium conduction.
In the technical scheme, the lithium-sulfur battery is assembled by using sulfur as a positive electrode and a lithium sheet as a negative electrode, the capacity retention rate is 73-76% after the lithium-sulfur battery is cycled for 100 circles under the multiplying power of 0.5C, and the average coulombic efficiency is 99.04-99.53% after the lithium-sulfur battery is cycled for 20 circles.
The invention has the following beneficial effects:
the preparation method of the invention adopts water and ethanol as solvents, which reduces the cost and protects the environment, so that the diaphragm has the special effects of sulfur interception and lithium conduction, and the aluminum oxide inorganic coating is coated on the basis, thereby improving the temperature resistance and the tensile strength of the battery diaphragm.
Detailed Description
The technical scheme of the invention is further explained by combining specific examples.
In the following embodiments, the high-speed disperser manufacturer is Ningde Jiatuo Intelligent Equipment, Inc.;
the stirring of the following examples was carried out using a double planetary power mixer, model: HY-DLH43L, manufacturer: guangzhou Hongshang mechanical science and technology, Inc.;
the sand mill is a full ceramic nanometer grinding machine, and has the model: PT-5L, the manufacturer is a Noo mechanical equipment Co., Ltd.
Test equipment for voltage decomposition: withstand voltage insulation analyzer, model: AN9636HS, manufacturer: qingdao Ainuo
Test equipment for heat shrinkage: a high temperature test chamber;
tensile strength: shimadzu intelligent electronic tensile testing machine.
Example 1
A preparation method of a lithium-sulfur battery composite coating diaphragm comprises the following steps:
1) uniformly mixing a carbon conductor and a lithium conducting polymer to obtain a mixture A, mixing the mixture A with a solution B, and stirring in a high-speed dispersion machine for 3 hours to uniformly disperse the mixture A in the solution B to obtain a mixture C, wherein the ratio of the carbon conductor to the lithium conducting polymer is 1: 1.5, the solid content of the mixture A in the mixture C is 2.76%, the solution B is a mixture of alcohol and water, and the ratio of the alcohol to the water in the solution B is 1: 3, the carbon conductor is graphene, and the lithium conducting polymer is polyacrylic acid;
2) adding polyvinylidene fluoride and polyoxyethylene alkylated ether into the mixture C under the stirring condition, and uniformly stirring to obtain a first slurry, wherein the polyvinylidene fluoride accounts for 3 wt% of the mixture A, and the polyoxyethylene alkylated ether accounts for 5 wt% of the mixture A;
3) preparing a polypropylene film as a base film, coating the first slurry on the positive electrode side of the base film, and obtaining a first coating film with the thickness of 1 mu m on the base film;
4) coating a second slurry on the first coating film for forming a second coating film with a thickness of 1 μm, and drying at 45 ℃ for 0.5s to obtain the composite coating diaphragm of the lithium-sulfur battery, wherein the second slurry is obtained by the following method: mixing alumina powder and deionized water, stirring for 2 hours in a stirrer, introducing the mixture into a sand mill, continuously sanding for 4 hours to obtain a mixture D, adding a binder (polyethylacrylate), a dispersant (polyquaternium), a pore-forming additive (polyethylene glycol), sodium carboxymethylcellulose and polyoxyethylene alkyl ether into the mixture D, and uniformly mixing to obtain a second slurry, wherein the solid content of the alumina powder in the mixture D is 28.6%, the binder accounts for 2 wt% of the alumina powder, the dispersant accounts for 5 wt% of the alumina powder, the pore-forming additive accounts for 3 wt% of the alumina powder, the sodium carboxymethylcellulose accounts for 5 wt% of the alumina powder, and the polyoxyethylene alkyl ether accounts for 5 wt% of the alumina powder.
The decomposition voltage of the lithium-sulfur battery composite coating diaphragm prepared in the embodiment 1 is 4.7V, the thermal shrinkage rate at 130 ℃ for 1 hour is 1.3 percent, and the tensile strength is 1450Kg/cm2. The lithium-sulfur battery is assembled by adopting sulfur as a positive electrode and a lithium sheet as a negative electrode, the capacity retention rate is 75% after the battery is cycled for 100 circles under the multiplying power of 0.5C, and the average coulombic efficiency is 99.34% after the battery is cycled for 20 circles.
Example 2
A preparation method of a lithium-sulfur battery composite coating diaphragm comprises the following steps:
1) uniformly mixing a carbon conductor and a lithium conducting polymer to obtain a mixture A, mixing the mixture A with a solution B, and stirring in a high-speed dispersion machine for 3 hours to uniformly disperse the mixture A in the solution B to obtain a mixture C, wherein the ratio of the carbon conductor to the lithium conducting polymer is 1: and 2, the solid content of the mixture A in the mixture C is 2.9%, the solution B is a mixture of alcohol and water, and the ratio of the alcohol to the water in the solution B is 1: 3, the carbon conductor is graphene, and the lithium conducting polymer is polyacrylic acid;
2) adding polyvinylidene fluoride and polyoxyethylene alkylated ether into the mixture C under the stirring condition, and uniformly stirring to obtain a first slurry, wherein the polyvinylidene fluoride accounts for 3 wt% of the mixture A, and the polyoxyethylene alkylated ether accounts for 4.9 wt% of the mixture A;
3) preparing a polypropylene film as a base film, coating the first slurry on the positive electrode side of the base film, and obtaining a first coating film with the thickness of 1 mu m on the base film;
4) coating a second slurry on the first coating film for forming a second coating film with a thickness of 1 μm, and drying at 80 ℃ for 0.5s to obtain the composite coating diaphragm of the lithium-sulfur battery, wherein the second slurry is obtained by the following method: mixing alumina powder and deionized water, stirring for 2 hours in a stirrer, introducing the mixture into a sand mill, continuously sanding for 4 hours to obtain a mixture D, adding a binder (polyethylacrylate), a dispersant (polyquaternium), a pore-forming additive (polyethylene glycol), sodium carboxymethylcellulose and polyoxyethylene alkyl ether into the mixture D, and uniformly mixing to obtain a second slurry, wherein the solid content of the alumina powder in the mixture D is 23.1%, the binder accounts for 2 wt% of the alumina powder, the dispersant accounts for 5 wt% of the alumina powder, the pore-forming additive accounts for 3 wt% of the alumina powder, the sodium carboxymethylcellulose accounts for 5 wt% of the alumina powder, and the polyoxyethylene alkyl ether accounts for 5 wt% of the alumina powder.
The decomposition voltage of the lithium-sulfur battery composite coating diaphragm prepared in the embodiment 2 is 4.5V, the thermal shrinkage rate at 130 ℃ for 1 hour is 1.6 percent, and the tensile strength is 1450Kg/cm2. The lithium-sulfur battery is assembled by adopting sulfur as a positive electrode and a lithium sheet as a negative electrode, the capacity retention rate is 73% after the battery is cycled for 100 circles under the multiplying power of 0.5C, and the average coulombic efficiency is 99.12% after the battery is cycled for 20 circles.
Example 3
A preparation method of a lithium-sulfur battery composite coating diaphragm comprises the following steps:
1) uniformly mixing a carbon conductor and a lithium conducting polymer to obtain a mixture A, mixing the mixture A with a solution B, and stirring in a high-speed dispersion machine for 3 hours to uniformly disperse the mixture A in the solution B to obtain a mixture C, wherein the ratio of the carbon conductor to the lithium conducting polymer is 1: and 7, the solid content of the mixture A in the mixture C is 2.9%, the solution B is a mixture of alcohol and water, and the ratio of the alcohol to the water in the solution B is 1: 3, the carbon conductor is graphene, and the lithium conducting polymer is polyacrylic acid;
2) adding polyvinylidene fluoride and polyoxyethylene alkylated ether into the mixture C under the stirring condition, and uniformly stirring to obtain a first slurry, wherein the polyvinylidene fluoride accounts for 3 wt% of the mixture A, and the polyoxyethylene alkylated ether accounts for 5 wt% of the mixture A;
3) preparing a polypropylene film as a base film, coating the first slurry on the positive electrode side of the base film, and obtaining a first coating film with the thickness of 1 mu m on the base film;
4) coating a second slurry on the first coating film for forming a second coating film with a thickness of 1 μm, and drying at 80 ℃ for 0.5s to obtain the composite coating diaphragm of the lithium-sulfur battery, wherein the second slurry is obtained by the following method: mixing alumina powder and deionized water, stirring for 2 hours in a stirrer, introducing the mixture into a sand mill, continuously sanding for 4 hours to obtain a mixture D, adding a binder (polyethylacrylate), a dispersant (polyquaternium), a pore-forming additive (polyethylene glycol), sodium carboxymethylcellulose and polyoxyethylene alkyl ether into the mixture D, and uniformly mixing to obtain a second slurry, wherein the solid content of the alumina powder in the mixture D is 33.3%, the binder accounts for 2 wt% of the alumina powder, the dispersant accounts for 5 wt% of the alumina powder, the pore-forming additive accounts for 3 wt% of the alumina powder, the sodium carboxymethylcellulose accounts for 5 wt% of the alumina powder, and the polyoxyethylene alkyl ether accounts for 5 wt% of the alumina powder.
The decomposition voltage of the composite coating diaphragm of the lithium-sulfur battery prepared in the embodiment 3 is 4.5V, the thermal shrinkage rate at 130 ℃ for 1 hour is 1.5 percent, and the tensile strength is 1440Kg/cm2. The lithium-sulfur battery is assembled by adopting sulfur as a positive electrode and a lithium sheet as a negative electrode, the capacity retention rate is 74% after the battery is cycled for 100 circles under the multiplying power of 0.5C, and the average coulombic efficiency is 99.04% after the battery is cycled for 20 circles.
Example 4
A preparation method of a lithium-sulfur battery composite coating diaphragm comprises the following steps:
1) uniformly mixing a carbon conductor and a lithium conducting polymer to obtain a mixture A, mixing the mixture A with a solution B, and stirring in a high-speed dispersion machine for 3 hours to uniformly disperse the mixture A in the solution B to obtain a mixture C, wherein the ratio of the carbon conductor to the lithium conducting polymer is 2: and 7, the solid content of the mixture A in the mixture C is 4%, the solution B is a mixture of alcohol and water, and the ratio of the alcohol to the water in the solution B is 2: 3, the carbon conductor is graphene, and the lithium conducting polymer is sulfonated polyether sulfone;
2) adding polyvinylidene fluoride and polyoxyethylene alkylated ether into the mixture C under the stirring condition, and uniformly stirring to obtain a first slurry, wherein the polyvinylidene fluoride accounts for 4 wt% of the mixture A, and the polyoxyethylene alkylated ether accounts for 7 wt% of the mixture A;
3) preparing a polypropylene film as a base film, coating the first slurry on the positive electrode side of the base film, and obtaining a first coating film with the thickness of 2 mu m on the base film;
4) coating a second slurry on the first coating film for forming a second coating film with a thickness of 0.5 μm, and drying at 80 ℃ for 0.5s to obtain the composite coating diaphragm of the lithium-sulfur battery, wherein the second slurry is obtained by the following method: mixing alumina powder and deionized water, stirring for 2 hours in a stirrer, introducing the mixture into a sand mill, continuing sanding for 4 hours to obtain a mixture D, adding a binder (polyethylacrylate), a dispersant (polyquaternium), a pore-forming additive (lithium chloride), sodium carboxymethylcellulose and polyoxyethylene alkyl ether into the mixture D, and uniformly mixing to obtain a second slurry, wherein the solid content of the alumina powder in the mixture D is 40%, the binder accounts for 3 wt% of the alumina powder, the dispersant accounts for 7 wt% of the alumina powder, the pore-forming additive accounts for 4 wt% of the alumina powder, the sodium carboxymethylcellulose accounts for 7 wt% of the alumina powder, and the polyoxyethylene alkyl ether accounts for 8 wt% of the alumina powder.
The decomposition voltage of the composite coating diaphragm of the lithium-sulfur battery prepared in the embodiment 4 is 4.7V, the thermal shrinkage rate of the composite coating diaphragm at 130 ℃ for 1 hour is 1.3 percent, and the tensile strength is 1470Kg/cm2. The lithium-sulfur battery is assembled by adopting sulfur as a positive electrode and a lithium sheet as a negative electrodeThe capacity retention rate of the cell after 100 cycles under the multiplying power of 0.5C is 76%, and the average coulombic efficiency of the cell after 20 cycles is 99.45%.
Example 5
A preparation method of a lithium-sulfur battery composite coating diaphragm comprises the following steps:
1) uniformly mixing a carbon conductor and a lithium conducting polymer to obtain a mixture A, mixing the mixture A with a solution B, and stirring in a high-speed dispersion machine for 3 hours to uniformly disperse the mixture A in the solution B to obtain a mixture C, wherein the ratio of the carbon conductor to the lithium conducting polymer is 3: and 7, the solid content of the mixture A in the mixture C is 5%, the solution B is a mixture of alcohol and water, and the ratio of the alcohol to the water in the solution B is 2: 3, the carbon conductor is graphene, and the lithium conducting polymer is polymethyl methacrylate;
2) adding polyvinylidene fluoride and polyoxyethylene alkylated ether into the mixture C under the stirring condition, and uniformly stirring to obtain a first slurry, wherein the polyvinylidene fluoride accounts for 4 wt% of the mixture A, and the polyoxyethylene alkylated ether accounts for 7 wt% of the mixture A;
3) preparing a polypropylene film as a base film, coating the first slurry on the positive electrode side of the base film, and obtaining a first coating film with the thickness of 3 mu m on the base film;
4) coating a second slurry on the first coating film for forming a second coating film with a thickness of 0.5 μm, and drying at 80 ℃ for 0.5s to obtain the composite coating diaphragm of the lithium-sulfur battery, wherein the second slurry is obtained by the following method: mixing alumina powder and deionized water, stirring for 2 hours in a stirrer, introducing the mixture into a sand mill, continuing sanding for 4 hours to obtain a mixture D, adding a binder (polyethylacrylate), a dispersant (polyquaternium), a pore-forming additive (polyvinylpyrrolidone), sodium carboxymethylcellulose and polyoxyethylene alkyl ether into the mixture D, and uniformly mixing to obtain a second slurry, wherein the solid content of the alumina powder in the mixture D is 40%, the binder is 4 wt% of the alumina powder, the dispersant is 6 wt% of the alumina powder, the pore-forming additive is 4 wt% of the alumina powder, the sodium carboxymethylcellulose is 7 wt% of the alumina powder, and the polyoxyethylene alkyl ether is 7 wt% of the alumina powder.
The decomposition voltage of the lithium-sulfur battery composite coating diaphragm prepared in the embodiment 5 is 4.7V, the heat shrinkage rate at 130 ℃ for 1 hour is 1.4 percent, and the tensile strength is 1457Kg/cm2. The lithium-sulfur battery is assembled by adopting sulfur as a positive electrode and a lithium sheet as a negative electrode, the capacity retention rate is 76% after the battery is cycled for 100 circles under the multiplying power of 0.5C, and the average coulombic efficiency is 99.53% after the battery is cycled for 20 circles.
Example 6
A preparation method of a lithium-sulfur battery composite coating diaphragm comprises the following steps:
1) uniformly mixing a carbon conductor and a lithium conducting polymer to obtain a mixture A, mixing the mixture A with a solution B, and stirring in a high-speed dispersion machine for 3 hours to uniformly disperse the mixture A in the solution B to obtain a mixture C, wherein the ratio of the carbon conductor to the lithium conducting polymer is 2: and 5, the solid content of the mixture A in the mixture C is 3%, the solution B is a mixture of alcohol and water, and the ratio of the alcohol to the water in the solution B is 1: 3, the carbon conductor is graphene, the lithium conducting polymer is a mixture of polyacrylic acid and sulfonated polyether sulfone, and the mass ratio of the polyacrylic acid to the sulfonated polyether sulfone is 1: 1;
2) adding polyvinylidene fluoride and polyoxyethylene alkylated ether into the mixture C under the stirring condition, and uniformly stirring to obtain a first slurry, wherein the polyvinylidene fluoride accounts for 4 wt% of the mixture A, and the polyoxyethylene alkylated ether accounts for 7 wt% of the mixture A;
3) preparing a polypropylene film as a base film, coating the first slurry on the positive electrode side of the base film, and obtaining a first coating film with the thickness of 1 mu m on the base film;
4) coating a second slurry on the first coating film for forming a second coating film with a thickness of 1 μm, and drying at 80 ℃ for 0.5s to obtain the composite coating diaphragm of the lithium-sulfur battery, wherein the second slurry is obtained by the following method: mixing alumina powder and deionized water, stirring for 2 hours in a stirrer, introducing the mixture into a sand mill, continuing sanding for 4 hours to obtain a mixture D, adding a binder (polyethylacrylate), a dispersant (polyquaternium), a pore-forming additive (sodium nitrate), sodium carboxymethylcellulose and polyoxyethylene alkyl ether into the mixture D, and uniformly mixing to obtain a second slurry, wherein the solid content of the alumina powder in the mixture D is 20%, the binder accounts for 3 wt% of the alumina powder, the dispersant accounts for 6 wt% of the alumina powder, the pore-forming additive accounts for 4 wt% of the alumina powder, the sodium carboxymethylcellulose accounts for 10 wt% of the alumina powder, and the polyoxyethylene alkyl ether accounts for 5 wt% of the alumina powder.
The decomposition voltage of the lithium-sulfur battery composite coating membrane prepared in example 6 is 4.7V, the thermal shrinkage at 130 ℃ for 1 hour is 1.5%, and the tensile strength is 1448Kg/cm2. The lithium-sulfur battery is assembled by adopting sulfur as a positive electrode and a lithium sheet as a negative electrode, the capacity retention rate is 74% after the battery is cycled for 100 circles under the multiplying power of 0.5C, and the average coulombic efficiency is 99.24% after the battery is cycled for 20 circles.
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. A preparation method of a lithium-sulfur battery composite coating diaphragm is characterized by comprising the following steps:
1) uniformly mixing a carbon conductor and a lithium conducting polymer to obtain a mixture A, and uniformly dispersing the mixture A in a solution B to obtain a mixture C, wherein the ratio of the carbon conductor to the lithium conducting polymer is (1-3): (2-9), the solid content of the mixture A in the mixture C is 2-5%, the solution B is a mixture of alcohol and water, and the ratio of the alcohol to the water in the solution B is (1-2): (2-3), the carbon conductor is graphite, and the lithium conducting polymer is one or more of polyacrylic acid, sulfonated polyether sulfone and polymethyl methacrylate;
2) under the stirring condition, adding polyvinylidene fluoride and polyoxyethylene alkylated ether into the mixture C, and uniformly stirring to obtain a first slurry, wherein the polyvinylidene fluoride accounts for 3-5 wt% of the mixture A, and the polyoxyethylene alkylated ether accounts for 4.5-8 wt% of the mixture A;
3) coating the first slurry on the positive electrode side of a base film to obtain a first coating film on the base film, wherein the base film is a polypropylene film;
4) coating a second slurry on the first coating film for forming a second coating film, and drying to obtain the lithium-sulfur battery composite coating diaphragm, wherein the second slurry is obtained by the following method: uniformly mixing alumina powder and deionized water to obtain a mixture D, and then adding a binder, a dispersant, a pore-forming additive, sodium carboxymethylcellulose and polyoxyethylene alkyl ether into the mixture D to uniformly mix to obtain a second slurry, wherein the solid content of the alumina powder in the mixture D is 20-60%, the binder is 2-5 wt% of the alumina powder, the dispersant is 5-7 wt% of the alumina powder, the pore-forming additive is 3-4 wt% of the alumina powder, the sodium carboxymethylcellulose is 5-10 wt% of the alumina powder, and the polyoxyethylene alkyl ether is 5-8 wt% of the alumina powder; the binder is polyacrylate, the dispersant is organic ammonium salt, and the pore-forming additive is one or more of polyethylene glycol, lithium chloride, polyvinylpyrrolidone and sodium nitrate.
2. The production method according to claim 1, wherein in the step 1), the graphite is graphene, natural graphite, or artificial graphite;
in the step 1), the mixture a is mixed with the solution B and then stirred in a high-speed disperser for at least 3 hours to achieve uniform dispersion of the mixture a in the solution B.
3. The production method according to claim 2, wherein in the step 3), the thickness of the first coating film is 0.5 to 4 μm, preferably 1 μm.
4. The preparation method according to claim 3, wherein in the step 4), the alumina powder is mixed with deionized water, the mixture is stirred for 2 to 3 hours in a stirrer and then introduced into a sand mill for continuous sanding for 4 to 5 hours to obtain the mixture D;
in the step 4), the thickness of the second coating film is 0.5 to 2 μm.
5. The method according to claim 1, wherein in the step 4), the polyacrylate is polyethylacrylate, and the organic ammonium salt is polyquaternium.
6. The composite coating diaphragm of the lithium-sulfur battery obtained by the preparation method of any one of claims 1 to 5.
7. Use of the composite coated separator for lithium-sulfur battery according to claim 6 for increasing tensile strength.
8. Use of the composite coated separator for lithium sulfur battery according to claim 6 for improving temperature resistance.
9. The use of the composite coated separator for lithium sulfur battery as defined in claim 6 for trapping and conducting lithium.
10. The application of the lithium-sulfur battery as claimed in claim 9, wherein the sulfur is used as a positive electrode, the lithium sheet is used as a negative electrode, the lithium-sulfur battery is assembled, the capacity retention rate is 73-76% after the lithium-sulfur battery is cycled for 100 circles under the multiplying power of 0.5C, and the average coulombic efficiency is 99.04-99.53% after the lithium-sulfur battery is cycled for 20 circles.
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| CN112909425A (en) * | 2021-01-20 | 2021-06-04 | 河北金力新能源科技股份有限公司 | High-efficiency long-life lithium-sulfur battery diaphragm and preparation method thereof |
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