CN107919452B - Diaphragm for lithium ion battery, preparation method of diaphragm and lithium ion battery - Google Patents
Diaphragm for lithium ion battery, preparation method of diaphragm and lithium ion battery Download PDFInfo
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- CN107919452B CN107919452B CN201711137173.8A CN201711137173A CN107919452B CN 107919452 B CN107919452 B CN 107919452B CN 201711137173 A CN201711137173 A CN 201711137173A CN 107919452 B CN107919452 B CN 107919452B
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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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/431—Inorganic material
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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
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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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
- H01M10/058—Construction or manufacture
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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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/403—Manufacturing processes of separators, membranes or diaphragms
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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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
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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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
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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
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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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Cell Separators (AREA)
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Abstract
The invention belongs to the field of lithium ion battery materials, and particularly relates to a diaphragm for a lithium ion battery, a preparation method of the diaphragm and the lithium ion battery. The invention provides a diaphragm for a lithium ion battery, which comprises: a halogen element-containing polymer matrix and antimony oxide particles; the polymer matrix containing halogen elements is coated with the antimony oxide particles. The separator for a lithium ion battery of the present invention uses a halogen element-containing polymer substrate, and antimony oxide particles are coated on the surface of the halogen element-containing polymer substrate. The performance test shows that the diaphragm for the lithium ion battery has strong thermal stability, high liquid absorption rate, high ionic conductivity and short self-extinguishing time, and can solve the problems of poor wettability, low safety and the like of the diaphragm for the lithium ion battery and electrolyte.
Description
Technical Field
The invention belongs to the field of lithium ion battery materials, and particularly relates to a diaphragm for a lithium ion battery, a preparation method of the diaphragm and the lithium ion battery.
Background
In recent years, with the increasing demands for volume and endurance of digital products and the rapid development of electric vehicles, conventional chemical power sources such as lead storage batteries, nickel-metal hydride batteries, and nickel-cadmium batteries have failed to meet the demands. Lithium ion batteries are widely used and gradually replace traditional chemical power sources due to their high operating voltage, long cycle life, and high energy density. The lithium ion battery consists of four key parts, namely a positive electrode, a negative electrode, a diaphragm and electrolyte, wherein the performance of the lithium ion battery, such as cycle life, rate capability and safety, can be greatly influenced by the properties of the diaphragm.
The materials of the diaphragm which is widely used at present are polyolefine, such as polyethylene, polypropylene and the like. Problems with polyolefin separators include: the wettability of the diaphragm and the electrolyte is poor, the diaphragm cannot be well wetted with the electrolyte, and the cycle and rate performance of the battery are affected. In addition, the thermal stability of the polyolefin diaphragm is poor, the melting point of the polyethylene diaphragm is only about 130 ℃, the melting point of the polypropylene diaphragm is about 160 ℃, the electrolyte is flammable organic solvent, and when the battery is in high temperature or under the condition of a local short circuit and heat release and other extreme conditions, the diaphragm is heated and shrunk to cause large-area contact short circuit of the anode and the cathode and release heat, so that the combustion and explosion of the battery are caused.
Disclosure of Invention
In view of the above, the invention provides a diaphragm for a lithium ion battery, which is used for solving the problems of poor wettability and low safety of the existing diaphragm for the lithium ion battery and an electrolyte.
The specific technical scheme of the invention is as follows:
a separator for a lithium ion battery, comprising: a halogen element-containing polymer matrix and antimony oxide particles;
the polymer matrix containing halogen elements is coated with the antimony oxide particles.
Preferably, the mass percent of the antimony oxide particles is 1-50%.
Preferably, the polymer matrix containing halogen elements comprises one or more of a polyvinylidene fluoride matrix, a polytetrafluoroethylene matrix, a polyvinyl chloride matrix, a polyvinylidene fluoride-hexafluoropropylene copolymer matrix, a polyvinylidene fluoride-chlorotrifluoroethylene copolymer matrix, a chlorinated polyethylene matrix and a chlorinated polypropylene matrix.
Preferably, the antimony oxide particles comprise one or more of antimony trioxide, antimony pentoxide and antimony oxychloride.
The invention also provides a preparation method of the diaphragm for the lithium ion battery, which comprises the following steps:
a) mixing a binder and a solvent, and adding antimony oxide particles to form slurry;
b) and coating the slurry on the polymer matrix containing the halogen element to obtain the diaphragm for the lithium ion battery.
Preferably, the mass ratio of the antimony oxide particles to the binder is 1-49: 1.
preferably, the binder comprises one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-chlorotrifluoroethylene, polyvinyl alcohol, styrene butadiene rubber and carboxymethyl cellulose;
the solvent includes one or more of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran, acetone, ethanol, and water.
Preferably, the coating is spray coating or flow coating.
The invention also provides a lithium ion battery, which comprises a diaphragm and electrolyte, wherein the diaphragm is the diaphragm for the lithium ion battery or the diaphragm for the lithium ion battery prepared by the preparation method of the technical scheme.
Further, the method also comprises the following steps: a flame retardant additive;
the flame retardant additive is added to the electrolyte.
In summary, the present invention provides a separator for a lithium ion battery, including: a halogen element-containing polymer matrix and antimony oxide particles; the polymer matrix containing halogen elements is coated with the antimony oxide particles. The separator for a lithium ion battery of the present invention uses a halogen element-containing polymer substrate, and antimony oxide particles are coated on the surface of the halogen element-containing polymer substrate. The performance test shows that the diaphragm for the lithium ion battery has strong thermal stability, high liquid absorption rate, high ionic conductivity and short self-extinguishing time, and can solve the problems of poor wettability, low safety and the like of the diaphragm for the lithium ion battery and electrolyte.
Detailed Description
The invention provides a diaphragm for a lithium ion battery, which is used for solving the problems of poor wettability and low safety of the existing diaphragm for the lithium ion battery and an electrolyte.
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A separator for a lithium ion battery, comprising: a halogen element-containing polymer matrix and antimony oxide particles;
the halogen element-containing polymer matrix is coated with antimony oxide particles.
In the present invention, the mass percentage of the antimony oxide particles is 1% to 50%, and the mass percentage of the antimony oxide particles is more preferably 10% to 30%.
In the invention, the polymer matrix containing halogen elements comprises one or more of polyvinylidene fluoride matrix, polytetrafluoroethylene matrix, polyvinyl chloride matrix, polyvinylidene fluoride-hexafluoropropylene copolymer matrix, polyvinylidene fluoride-chlorotrifluoroethylene copolymer matrix, chlorinated polyethylene matrix and chlorinated polypropylene matrix.
In the invention, the polymer matrix containing halogen elements is an electrospun or non-woven fabric polymer, the thickness of the polymer matrix containing halogen elements is 5-200 mu m, and the porosity is 30-90%. The halogen element-containing polymer matrix is either self-made or commercially available.
In the invention, the antimony oxide particles comprise one or more of antimony trioxide, antimony pentoxide and antimony oxychloride, and the particle size of the antimony oxide particles is 0.02-2 μm.
According to the invention, the existence of the antimony oxide particles on the surface of the diaphragm can not only improve the thermal stability of the diaphragm, the wettability of the diaphragm and electrolyte, the ionic conductivity and other electrochemical properties of the diaphragm, but also fully exert the flame retardant property of the antimony oxide particles under the action of halogen elements, so that the diaphragm has and exerts excellent flame retardant property.
The invention also provides a preparation method of the diaphragm for the lithium ion battery, which comprises the following steps:
a) mixing a binder and a solvent, and adding antimony oxide particles to form slurry;
b) and coating the slurry on the polymer matrix containing the halogen element to obtain the diaphragm for the lithium ion battery.
In the invention, the mass ratio of the antimony oxide particles to the binder is 1-49: 1, the mass ratio of the antimony oxide particles to the binder is more preferably 5.67-19: 1.
the binder comprises one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-chlorotrifluoroethylene, polyvinyl alcohol, styrene-butadiene rubber and carboxymethyl cellulose;
the solvent comprises one or more of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran, acetone, ethanol, and water.
In the present invention, after the slurry is coated on the polymer substrate containing halogen element, and before the separator for lithium ion battery is obtained, the method further includes: the solvent was removed by drying.
The slurry is applied to one surface or both surfaces of the halogen element-containing polymer substrate.
In the present invention, the coating is spray coating or flow coating.
The preparation method of the diaphragm for the lithium ion battery is simple to operate and suitable for popularization and application.
The present invention also provides a lithium ion battery comprising: a separator for a lithium ion battery and an electrolyte.
In the invention, the method also comprises the following steps: a flame retardant additive;
the flame retardant additive is added to the electrolyte.
In the invention, the flame retardant additive is one or more of trimethyl phosphate, triethyl phosphate, triphenyl phosphate, diphenyl cresyl phosphate, tributyl phosphate, dimethyl methyl phosphonate, fluoro methyl ethylene carbonate, difluoro methyl ethylene carbonate and butyrolactone, and the mass fraction of the flame retardant additive is 0.1-10%.
In the prior art, in order to improve the safety of a lithium ion battery, the thermal stability of a diaphragm for the lithium ion battery is generally improved, and a flame retardant component is added into an electrolyte. The inorganic particles are introduced into the diaphragm, so that the thermal stability of the diaphragm can be improved, the wettability of the diaphragm and electrolyte can be improved, the ionic conductivity of the diaphragm is increased, and the electrochemical performance of the battery is finally improved. However, the safety problem of electrolyte combustion cannot be solved by improving the thermal stability of the separator alone. The flame retardant is added into the electrolyte to slow down the combustion of the electrolyte, but the actual flame retardant effect is related to the flame retardant content in the electrolyte, the flame retardant effect cannot be achieved when the flame retardant content in the electrolyte is low, and the electrochemical performance of the battery is greatly influenced when the flame retardant content is high.
In the invention, the lithium ion battery comprising the diaphragm for the lithium ion battery has excellent electrochemical performance and very high safety. The flame-retardant diaphragm uses an electrospun or non-woven fabric polymer containing halogen elements as a substrate, and antimony oxide particles are coated on the substrate by a spraying or casting method to prepare the diaphragm for the lithium ion battery with high-efficiency flame-retardant performance. The existence of antimony oxide particles in the diaphragm can improve the thermal stability of the diaphragm, the wettability with electrolyte, the ionic conductivity and other electrochemical properties of the diaphragm, and meanwhile, the antimony oxide particles can fully exert the flame retardant property under the action of halogen elements, so that the electrochemical properties of the diaphragm are improved, and the safety of the battery is improved from multiple aspects.
In the invention, antimony oxide particles are introduced into the diaphragm as an inorganic substance, so that the thermal stability, the wettability with electrolyte, the ionic conductivity and the electrochemical performance of the diaphragm can be improved, and the safety and the electrochemical performance of the battery are improved.
The antimony oxide particles are coated on the surface of the diaphragm, so that the antimony oxide particles can be rapidly melted on the surface of an object to form a protective film in the initial combustion stage, the combustion temperature is reduced through an internal endothermic reaction to achieve a flame retardant effect, and the flame retardancy of the antimony oxide particles is improved by coating the antimony oxide particles on the surface of a substrate. Although the antimony oxide particles have a general flame retardant effect when used alone, the antimony oxide particles have a good synergistic effect when used together with a halide, and the overall flame retardant effect can be greatly improved. The antimony oxide particles are coated on the electrospinning or non-woven fabric of the halogen-containing substrate, so that the thermal stability and the wettability of the diaphragm can be improved, and the antimony oxide particles can be used as a flame retardant to hinder the combustion of the electrolyte and the diaphragm, so that the aim of improving the safety of the battery from multiple aspects is fulfilled. And secondly, antimony oxide particles are rapidly decomposed into various antimony compounds and halogen free radicals under the action of halogen, so that flame energy is consumed, the chemical process of combustion is changed, and the diaphragm has high-efficiency flame retardant performance.
The invention provides a diaphragm for a lithium ion battery, which comprises: a halogen element-containing polymer matrix and antimony oxide particles; the halogen element-containing polymer matrix is coated with antimony oxide particles. The separator for a lithium ion battery of the present invention uses a halogen element-containing polymer substrate, and antimony oxide particles are coated on the surface of the halogen element-containing polymer substrate. The performance test shows that the diaphragm for the lithium ion battery has strong thermal stability, high liquid absorption rate, high ionic conductivity and short self-extinguishing time, and can solve the problems of poor wettability, low safety and the like of the diaphragm for the lithium ion battery and electrolyte.
Example 1
Dissolving polyvinylidene fluoride-chlorotrifluoroethylene with the molecular weight of 27-29 ten thousand in dimethylformamide, and preparing a spinning solution with the mass percentage of 20%. Taking out 3mL of spinning solution, placing the spinning solution in an injector, wherein the inner diameter of a needle is 0.8mm, the positive high voltage is 12kV, the negative high voltage is 1.3kV, the injection speed of the spinning solution is 0.030mm/min, the temperature is 35 ℃, and preparing the polymer matrix through electrostatic spinning. Dissolving polyvinylidene fluoride-chlorotrifluoroethylene serving as a binder in a dimethyl formamide solvent, preparing a coating solution with the mass percentage of 2%, adding antimony trioxide into the coating solution, and uniformly dispersing, wherein the mass ratio of the antimony trioxide to the polyvinylidene fluoride-chlorotrifluoroethylene is 9: 1. coating the coating solution containing the antimony trioxide on two surfaces of a matrix prepared by electrostatic spinning, wherein the mass fraction of the antimony trioxide is 16%, and drying to remove the solvent to obtain the diaphragm for the lithium ion battery.
Example 2
Dissolving polyvinylidene fluoride-hexafluoropropylene with the molecular weight of 57-60 ten thousand in dimethylformamide to prepare a spinning solution with the mass percent of 20%. Taking out 3mL of spinning solution, placing the spinning solution in an injector, wherein the inner diameter of a needle head is 0.8mm, the positive high voltage is 12kV, the negative high voltage is 1.3kV, the injection speed of the spinning solution is 0.028mm/min, the temperature is 35 ℃, and preparing the polymer matrix through electrostatic spinning. Dissolving polyvinylidene fluoride-hexafluoropropylene serving as a binder in a dimethyl formamide solvent, preparing a coating solution with the mass percent of 2%, adding antimony trioxide into the coating solution, and uniformly dispersing, wherein the mass ratio of the antimony trioxide to the polyvinylidene fluoride chlorotrifluoroethylene is 92: 8. coating the coating solution containing the antimony trioxide on two surfaces of a matrix prepared by electrostatic spinning, wherein the mass fraction of the antimony trioxide is 18%, and drying to remove the solvent to obtain the diaphragm for the lithium ion battery.
Example 3
Dissolving polyvinylidene fluoride-chlorotrifluoroethylene with the molecular weight of 27-29 ten thousand and polyvinylidene fluoride with the molecular weight of 57-60 ten thousand in dimethylformamide to prepare spinning solution with the mass percent of 18%. Taking out 3mL of spinning solution, placing the spinning solution in an injector, wherein the inner diameter of a needle head is 0.8mm, the positive high voltage is 12.2kV, the negative high voltage is 1.3kV, the injection speed of the spinning solution is 0.028mm/min, the temperature is 35 ℃, and preparing the polymer matrix through electrostatic spinning. Dissolving polyvinylidene fluoride-chlorotrifluoroethylene serving as a binder in a dimethyl formamide solvent, preparing a coating solution with the mass percentage of 2%, adding antimony pentoxide into the coating solution, uniformly dispersing, coating the coating solution containing the antimony pentoxide on two surfaces of a matrix prepared by electrostatic spinning, wherein the mass fraction of the antimony pentoxide is 16%, and drying to remove the solvent to obtain the diaphragm for the lithium ion battery.
Example 4
Dissolving polyvinylidene fluoride with the molecular weight of 100-120 ten thousand in dimethylformamide to prepare a spinning solution with the mass percent of 18%. Taking out 3mL of spinning solution, placing the spinning solution in an injector, wherein the inner diameter of a needle head is 0.8mm, the positive high voltage is 12kV, the negative high voltage is 1.3kV, the injection speed of the spinning solution is 0.028mm/min, the temperature is 35 ℃, and preparing the polymer matrix through electrostatic spinning. Dissolving polyvinylidene fluoride-chlorotrifluoroethylene serving as a binder in a dimethyl formamide solvent, preparing a spraying solution with the mass percentage of 2%, adding antimony trioxide into the spraying solution, and uniformly dispersing, wherein the mass ratio of the antimony trioxide to the polyvinylidene fluoride-chlorotrifluoroethylene is 9: 1. and (3) spraying a coating solution containing antimony trioxide on two surfaces of a matrix prepared by electrostatic spinning by using a spray gun, wherein the mass fraction of the antimony trioxide is 22%, and drying to remove the solvent to obtain the diaphragm for the lithium ion battery.
Example 5
Dissolving polyvinylidene fluoride-chlorotrifluoroethylene with the molecular weight of 27-29 ten thousand in dimethylformamide, and preparing a spinning solution with the mass percentage of 20%. Taking out 3mL of spinning solution, placing the spinning solution in an injector, wherein the inner diameter of a needle head is 0.8mm, the positive high voltage is 12kV, the negative high voltage is 1.3kV, the injection speed of the spinning solution is 0.028mm/min, the temperature is 35 ℃, and preparing the polymer matrix through electrostatic spinning. Dissolving polyvinylidene fluoride-chlorotrifluoroethylene serving as a binder in a dimethyl formamide solvent, preparing a spraying solution with the mass percentage of 2%, adding antimony pentoxide into the spraying solution, and uniformly dispersing, wherein the mass ratio of the antimony pentoxide to the polyvinylidene fluoride-chlorotrifluoroethylene is 92: 8. and (3) spraying a coating solution containing antimony pentoxide to the two surfaces of the matrix prepared by electrostatic spinning by using a spray gun, wherein the mass fraction of the antimony trioxide is 20%, and drying to remove the solvent to obtain the diaphragm for the lithium ion battery.
Comparative example 1
Dissolving polyvinylidene fluoride with the molecular weight of 100-120 ten thousand in dimethylformamide to prepare a spinning solution with the mass percent of 18%. Taking out 3mL of spinning solution, placing the spinning solution in an injector, wherein the inner diameter of a needle is 0.8mm, the positive high voltage is 12kV, the negative high voltage is 1.3kV, the injection speed of the spinning solution is 0.028mm/min, the temperature is 35 ℃, and obtaining the polyvinylidene fluoride non-woven fabric diaphragm after spinning.
Comparative example 2
Dissolving polyvinylidene fluoride-chlorotrifluoroethylene with the molecular weight of 27-29 ten thousand in dimethylformamide, and preparing a spinning solution with the mass percentage of 20%. Adding antimony trioxide into the spinning solution and uniformly dispersing, wherein the mass ratio of the antimony trioxide to the polyvinylidene fluoride-chlorotrifluoroethylene is 1: 60. taking out 3mL of spinning solution, placing the spinning solution in an injector, wherein the inner diameter of a needle head is 0.8mm, the positive high voltage is 12kV, the negative high voltage is 1.3kV, the injection speed of the spinning solution is 0.028mm/min, the temperature is 35 ℃, and obtaining the diaphragm after spinning.
Comparative example 3
Dissolving 100-120 ten thousand of polyvinylidene fluoride with molecular weight in dimethylformamide, and preparing a spinning solution with the mass percent of 20%. Adding antimony pentoxide into the spinning solution and uniformly dispersing, wherein the mass ratio of the antimony pentoxide to the polyvinylidene fluoride is 1: 50. taking out 3mL of spinning solution, placing the spinning solution in an injector, wherein the inner diameter of a needle head is 0.8mm, the positive high voltage is 12kV, the negative high voltage is 1.3kV, the injection speed of the spinning solution is 0.028mm/min, the temperature is 35 ℃, and obtaining the diaphragm after spinning.
Comparative example 4
Polyacrylonitrile with a molecular weight of 15 ten thousand was dissolved in dimethylformamide, and a spinning solution with a mass percentage of 10% was prepared. And taking 5mL of spinning solution out, placing the spinning solution into an injector, wherein the inner diameter of a needle is 0.7mm, the positive high voltage is 15kV, the negative high voltage is 2.2kV, the injection speed of the spinning solution is 0.075mm/min, the temperature is 35 ℃, and preparing the polymer matrix through electrostatic spinning. Dissolving polyvinylidene fluoride-chlorotrifluoroethylene serving as a binder in a dimethyl formamide solvent, preparing a coating solution with the mass percentage of 2%, adding antimony trioxide into the coating solution, and uniformly dispersing, wherein the mass ratio of the antimony trioxide to the polyvinylidene fluoride-chlorotrifluoroethylene is 9: 1. coating the coating solution containing the antimony trioxide on two surfaces of a matrix prepared by electrostatic spinning, wherein the mass fraction of the antimony trioxide is 16%, and drying to remove the solvent to obtain the diaphragm for the ion battery.
Comparative example 5
Dissolving polyvinylidene fluoride with the molecular weight of 100-120 ten thousand in dimethylformamide to prepare a spinning solution with the mass percent of 18%. Taking out 3mL of spinning solution, placing the spinning solution in an injector, wherein the inner diameter of a needle head is 0.8mm, the positive high voltage is 12kV, the negative high voltage is 1.3kV, the injection speed of the spinning solution is 0.028mm/min, the temperature is 35 ℃, and preparing the polymer matrix through electrostatic spinning. Dissolving polyvinylidene fluoride-hexafluoropropylene serving as a binder in a dimethyl formamide solvent, preparing a coating solution with the mass percent of 2%, adding aluminum oxide into the coating solution, and uniformly dispersing, wherein the mass ratio of the aluminum oxide to the polyvinylidene fluoride chlorotrifluoroethylene is 9: 1. coating the coating solution containing aluminum oxide on two surfaces of a matrix prepared by electrostatic spinning, wherein the mass fraction of the aluminum oxide is 18%, and drying to remove the solvent to obtain the diaphragm for the lithium ion battery.
Example 6
The performance tests were performed on the separators of examples 1 to 5 and comparative examples 1 to 5, and the performance tests included: thermal stability test, imbibition rate test, ionic conductivity test and self-extinguishing time test.
And (3) testing thermal stability: cutting the diaphragm into a square of 2cm multiplied by 2cm, measuring the area of the diaphragm after being placed at 130 ℃ for 30min and comparing the area with the initial area, and calculating the percentage of the area of the diaphragm after heat treatment to the initial area.
And (3) testing the liquid absorption rate: weighing the mass m of the diaphragm1Then, completely soaking the diaphragm in the electrolyte for 4 hours, taking out the diaphragm, removing the redundant electrolyte on the surface of the diaphragm by using filter paper, and weighing the mass m2. The liquid absorption rate is calculated according to the following formula:
liquid absorption rate
And (3) ionic conductivity test: the intrinsic resistance R of the diaphragm was measured by an electrochemical impedance method using two stainless steel sheets as working electrodes, and the thickness of the diaphragm was measured at 5 points on any sample on the diaphragm using a micrometer (accuracy: 0.01mm) and the average was taken as the thickness d. The ionic conductivity of the separator is calculated as follows:
ionic conductivity
Wherein S is the contact area of the stainless steel sheet and the diaphragm, namely the effective area of the diaphragm.
Self-extinguishing time test: a5 cm × 5cm separator was taken, 1g of an electrolyte was dropped on the separator, ignited by a lighter, and the time from ignition to extinction was recorded.
In the above Performance testThe electrolyte used in the liquid absorption rate test and the self-extinguishing time test is 1mo/L LiPF6Ethylene carbonate + diethyl carbonate (volume ratio 1: 1) electrolyte.
The performance test results are shown in table 1, and the results show that the thermal stability of the diaphragms of examples 1 to 5 is obviously higher than that of the diaphragm of comparative example 1, and is equivalent to that of the diaphragms of comparative examples 2 to 5; the liquid absorption rate of the diaphragms of the examples 1 to 5 is obviously higher than that of the diaphragm of the comparative example 1 and higher than that of the diaphragms of the comparative examples 2 to 5; the ionic conductivity of the diaphragms of the examples 1 to 5 is obviously higher than that of the diaphragm of the comparative example 1 and is higher than that of the diaphragms of the comparative examples 2 to 5; the self-extinguishing time of the separators of examples 1-5 is significantly shorter than that of the separators of comparative examples 1-5. The result shows that the diaphragm of the invention uses the polymer matrix containing halogen elements, and the surface of the polymer matrix containing halogen elements is coated with antimony oxide particles, so that the performance of the diaphragm for the lithium ion battery can be obviously improved, and the problems of poor wettability and low safety of the existing diaphragm for the lithium ion battery and electrolyte are solved.
Table 1 separator performance test results
| Thermal stability (%) | Liquid absorption Rate (%) | Ionic conductivity (mS/cm) | Self-extinguishing time(s) | |
| Example 1 | 98 | 643 | 1.07 | 11 |
| Example 2 | 97 | 701 | 1.13 | 9 |
| Example 3 | 95 | 683 | 1.10 | 10 |
| Example 4 | 94 | 653 | 1.08 | 11 |
| Example 5 | 95 | 689 | 1.10 | 10 |
| Comparative example 1 | 86 | 572 | 0.89 | 22 |
| Comparative example 2 | 94 | 589 | 0.98 | 19 |
| Comparative example 3 | 95 | 613 | 1.02 | 21 |
| Comparative example 4 | 94 | 592 | 1.05 | 22 |
| Comparative example 5 | 93 | 603 | 0.99 | 20 |
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (7)
1. A separator for a lithium ion battery, comprising: a halogen element-containing polymer matrix and antimony oxide particles;
the polymer matrix containing halogen elements is coated with the antimony oxide particles;
the thickness of the polymer matrix containing halogen elements is 5-200 mu m, and the porosity is 30% -90%;
the particle size of the antimony oxide particles is 0.02-2 μm;
the coating is spray coating or flow coating;
the coating is specifically that the halogen-containing adhesive and antimony oxide particles are mixed and then coated by a spray coating method or a flow extension method;
the diaphragm for the lithium ion battery is a diaphragm for a lithium ion secondary battery;
the antimony oxide particles comprise one or more of antimony trioxide, antimony pentoxide and antimony oxychloride;
the mass percentage of the antimony oxide particles is 10-30%;
the polymer matrix containing halogen elements comprises one or more of a polyvinylidene fluoride matrix, a polytetrafluoroethylene matrix, a polyvinyl chloride matrix, a polyvinylidene fluoride-hexafluoropropylene copolymer matrix, a polyvinylidene fluoride-chlorotrifluoroethylene copolymer matrix, a chlorinated polyethylene matrix and a chlorinated polypropylene matrix;
the preparation method of the polymer matrix containing halogen elements comprises the following steps:
preparing the halogen element-containing polymer into a spinning solution;
placing the spinning solution in a syringe;
preparing the halogen-containing polymer matrix by electrostatic spinning;
the mass percentage of the spinning solution is 20%;
the inner diameter of the injector is 0.8mm, and the injection speed is 0.028 mm/min;
the temperature of the electrostatic spinning is 35 ℃, the positive high voltage is 12KV, and the negative high voltage is 1.2 KV.
2. A method for preparing the separator for the lithium ion battery according to claim 1, comprising:
a) mixing a binder and a solvent, and adding antimony oxide particles to form slurry;
b) and coating the slurry on the polymer matrix containing the halogen element to obtain the diaphragm for the lithium ion battery.
3. The method for preparing the separator for lithium ion battery according to claim 2, wherein the method comprises
The mass ratio of the antimony oxide particles to the binder is 1-49: 1.
4. the method of preparing the separator for a lithium ion battery according to claim 2, wherein the binder comprises one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-chlorotrifluoroethylene, polyvinyl alcohol, styrene butadiene rubber, and carboxymethyl cellulose;
the solvent includes one or more of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran, acetone, ethanol, and water.
5. The method for producing the separator for a lithium ion battery according to claim 2, wherein the coating is spray coating or flow coating.
6. A lithium ion battery comprises a separator and an electrolyte, and is characterized in that the separator is the separator for the lithium ion battery of claim 1 or the separator for the lithium ion battery prepared by the preparation method of any one of claims 2 to 5.
7. The lithium ion battery of claim 6, further comprising: a flame retardant additive;
the flame retardant additive is added to the electrolyte.
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| CN101501895A (en) * | 2006-02-16 | 2009-08-05 | 株式会社Lg化学 | Lithium secondary battery with enhanced heat-resistance |
| CN103633273A (en) * | 2013-12-10 | 2014-03-12 | 深圳市星源材质科技有限公司 | High-puncture-strength lithium ion battery diaphragm and preparation method thereof |
| CN104349897A (en) * | 2012-05-31 | 2015-02-11 | Lg化学株式会社 | Gas barrier film and method for manufacturing same |
| CN107195837A (en) * | 2017-04-28 | 2017-09-22 | 深圳市沃特玛电池有限公司 | Ceramic diaphragm and lithium ion battery |
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| GB8600401D0 (en) * | 1986-01-08 | 1986-02-12 | Hydrogen Systems Nv | Ion-permeable diaphragms |
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|---|---|---|---|---|
| CN101501895A (en) * | 2006-02-16 | 2009-08-05 | 株式会社Lg化学 | Lithium secondary battery with enhanced heat-resistance |
| CN104349897A (en) * | 2012-05-31 | 2015-02-11 | Lg化学株式会社 | Gas barrier film and method for manufacturing same |
| CN103633273A (en) * | 2013-12-10 | 2014-03-12 | 深圳市星源材质科技有限公司 | High-puncture-strength lithium ion battery diaphragm and preparation method thereof |
| CN107195837A (en) * | 2017-04-28 | 2017-09-22 | 深圳市沃特玛电池有限公司 | Ceramic diaphragm and lithium ion battery |
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