CN108346765B - Composite lithium ion battery diaphragm and preparation method thereof - Google Patents
Composite lithium ion battery diaphragm and preparation method thereof Download PDFInfo
- Publication number
- CN108346765B CN108346765B CN201810095512.9A CN201810095512A CN108346765B CN 108346765 B CN108346765 B CN 108346765B CN 201810095512 A CN201810095512 A CN 201810095512A CN 108346765 B CN108346765 B CN 108346765B
- Authority
- CN
- China
- Prior art keywords
- lithium ion
- ion battery
- polyimide
- battery separator
- composite lithium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
-
- 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
-
- 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
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Cell Separators (AREA)
Abstract
The invention provides a composite lithium ion battery diaphragm and a preparation method thereof, belonging to the field of lithium ion battery materials. The composite lithium ion battery diaphragm comprises a porous base layer diaphragm and a polyimide coating coated on one side of the porous base layer diaphragm. The invention can be applied to the central link of the development and application of the lithium ion battery.
Description
Technical Field
The invention belongs to the field of lithium ion battery materials, and particularly relates to a composite lithium ion battery diaphragm and a preparation method thereof.
Background
With the development of Lithium Ion Batteries (LIBs) in the power fields of electric vehicles, aerospace, large instruments, energy storage and the like, higher requirements are put forward on the comprehensive performance of the batteries, the safety problem of the lithium ion batteries is particularly important, and especially the problem of short circuit inside the batteries is solved. The diaphragm is an indispensable component of the lithium ion battery, and has the functions of preventing the contact of the positive electrode and the negative electrode from generating short circuit and providing a channel for the migration of lithium ions in electrolyte.
The LIB separator which is most widely used in the market at present is a conventional polyolefin separator. Although it has the advantages of good mechanical property, good chemical stability and low price, the poor thermal stability can affect the isolation between the positive electrode and the negative electrode and even cause safety accidents. In addition, the traditional polyolefin diaphragm also has the problems of low porosity, insufficient electrolyte wettability and the like, becomes one of the most main factors influencing the high-temperature safety performance and high-rate discharge performance of the lithium ion battery, and is a central link restricting the development and application of the lithium ion battery.
In order to improve the comprehensive performance of the traditional polyolefin diaphragm in the application of the lithium ion battery, researchers develop an organic-inorganic (ceramic) composite lithium ion battery diaphragm, the diaphragm is simple in preparation process, combines the advantages of flexibility of polyolefin materials and liquid absorption and high temperature resistance of inorganic materials, can avoid short circuit and explosion accidents of the battery, and has a certain effect of improving the safety of the lithium ion battery. However, the ceramic layer of the ceramic composite separator has a weak bonding force with the substrate film, and the ceramic layer is likely to fall off, so that patent application CN 201610024165.1 discloses a functional coating separator, in which a slurry composed of polyvinylidene fluoride, inorganic nano ceramic particles and water is coated on a polyolefin substrate, so that the slurry and the separator have more excellent adhesion and heat resistance. However, when the ceramic powder is used for a long time or in a high-strength environment, the ceramic powder may be exfoliated due to stress generated between the inorganic ceramic material and the polyolefin-based film. Thus, this preparation method obviously also requires the addition of a binder to improve the adhesion of the ceramic layer to the substrate, but the effect is not long lasting.
Polyimide (PI) is a high-performance organic high-molecular material, integrates the advantages of excellent dielectric property, high-temperature resistance, mechanical property, chemical stability and the like, and is one of high-molecular polymers with the most application prospect. Patent application CN201610055570.X discloses a preparation method of a polyamide-imide lithium ion battery diaphragm, wherein a polyamide-imide LIB diaphragm is prepared by a non-solvent induced phase inversion method, the temperature resistance of the diaphragm is greatly improved compared with a polyolefin diaphragm, and the tensile strength and the puncture strength are lower. Therefore, how to prepare a composite LIB separator with good mechanical properties and high temperature resistance is an important issue studied in the field.
Disclosure of Invention
The invention provides a composite lithium ion battery diaphragm and a preparation method thereof, and the lithium ion battery diaphragm improves the compatibility and adhesive force of a polyolefin base layer diaphragm and a coating layer, and can effectively improve the ionic conductivity and the cycle performance of a lithium ion battery.
In order to achieve the above objects, an aspect of the present invention provides a composite lithium ion battery separator including a porous base separator and a polyimide coating layer coated on one side of the porous base separator.
Preferably, the porous base layer separator has a thickness of: 5-40 μm, porosity: 30-80% of polyolefin separator.
Preferably, the polyolefin separator is one selected from a polyethylene lithium battery separator, a polypropylene lithium battery separator, and a composite separator having three or more layers, wherein the three or more layers are formed by spacing the polyethylene lithium battery separator and the polypropylene lithium battery separator.
Preferably, the thickness of the polyimide coating is 1-10 μm, and the content of polyimide in the battery separator is 1-10%.
Another aspect of the present invention provides a method for preparing a composite lithium ion battery separator according to any one of the above technical solutions, including the following steps:
and (3) synthesis of polyimide: adding dianhydride and diamine into a reaction vessel according to a molar ratio of 0.8-1.2 in a nitrogen environment, then adding an organic solvent, carrying out mechanical stirring reaction in an ice-water bath for 12-24h to obtain a polyamic acid solution, then adding acetic anhydride and triethylamine for chemical imidization, carrying out chemical imidization for 24-48h, precipitating the obtained polymer with ethanol, fully washing with ethanol and deionized water, placing in a drying oven, and drying at 60-120 ℃ overnight; vacuum drying at the temperature of 120-150 ℃ for 12-48h to obtain polyimide;
preparing a polyimide casting solution: according to the mass percentage concentration of 1-10%: 2-20%: 70-97% of the polyimide, the pore-forming agent and the organic solvent are mixed, and mechanically stirred in an oil bath at 50-100 ℃ until the mixture is uniformly mixed and completely dissolved, so as to obtain a polyimide casting solution;
preparing a composite lithium ion battery diaphragm: standing the obtained polyimide casting solution in an oil bath at 50-100 ℃ for 12-24h for defoaming, coating the polyimide casting solution on a porous base layer diaphragm, scraping the film by using a scraper, staying in the air for 3-300s, slowly and uniformly entering a coagulating bath containing a solvent and a non-solvent at room temperature for coagulation, washing the coagulated film with water, drying at 40-80 ℃ for 3-10h, and obtaining the composite lithium ion battery diaphragm after the water is completely volatilized.
Preferably, in the preparation step of the polyimide casting solution, the mass percentage concentration is 4-8%: 8-12%: 80-88% of the synthesized polyimide, the pore-forming agent and the organic solvent are mixed.
Preferably, in the preparation step of the composite lithium ion battery separator, the viscosity of the slurry after defoaming is 40 to 800 centipoise, and preferably 60 to 600 centipoise.
Preferably, the coagulation bath is a mixed solution of one or more organic solvents of DMAc, NMP, DMF, DMP or ethanol and non-solvent water, wherein the volume percentage concentration of the organic solvent is 10-90%, preferably 20-80%.
Preferably, the dianhydride is a binary organic anhydride selected from one of biphenyl tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, pyromellitic dianhydride, oxydiphenyltetracarboxylic anhydride and bisphenol a diether dianhydride; the diamine is organic diamine, and the organic diamine is selected from one of 4,4 '-diaminodiphenyl ether, 3, 4' -diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, 3 '-diphenyl sulfone diamine and 4, 4' -diphenyl sulfone diamine.
Preferably, the organic solvent is one or a mixture of two selected from N-methyl pyrrolidone, N-dimethyl acetamide, N-dimethyl formamide, dimethyl phthalate, dimethyl sulfoxide, m-cresol, tetrahydrofuran and methanol in any proportion; the pore-forming agent is selected from one or more of lithium chloride, sodium chloride, magnesium chloride, calcium carbonate, calcium chloride, methanol, ethanol, propanol, glycerol, acetone, acetic acid, tetrahydrofuran, polyethylene glycol with different molecular weights and polyvinylpyrrolidone with different molecular weights.
Compared with the prior art, the invention has the advantages and positive effects that:
1. the composite lithium electronic battery diaphragm prepared by the invention has higher tensile strength and puncture strength and high mechanical strength, and is beneficial to assembly of the lithium electronic battery and improvement of the safety performance of the lithium electronic battery.
2. The composite lithium electronic battery diaphragm prepared by the invention has good high temperature resistance, and the microporous structure of the diaphragm can not be damaged at higher temperature, for example, the surface pore structure of the diaphragm can not be damaged basically after the diaphragm is placed in a 130 ℃ oven for 1 h.
3. The prepared composite lithium electronic battery diaphragm can improve the compatibility of the polyolefin base film and the coating layer without adding an adhesive, and improves the adhesive force of the polyolefin base layer diaphragm and the coating layer.
4. The electrolyte wettability of the composite lithium electronic battery diaphragm prepared by the invention is effectively improved, the problem of poor wettability of polyolefin to the electrolyte can be effectively solved, the imbibition rate of the diaphragm is 150% after the diaphragm is soaked in lithium hexafluorophosphate electrolyte for 6 hours, and the capacity retention rate and the cycle life of a lithium electronic battery can be effectively improved.
Drawings
FIG. 1 is a picture of a PI product synthesized in the present invention;
FIG. 2 is a photograph of the contact angle of Celgrad polypropylene LIB separator with electrolyte;
FIG. 3 is a photograph showing contact angles between the PI composite LIB separator manufactured in example 1 of the present invention and an electrolyte;
FIG. 4 is a picture of the surface topography of the PE-based membrane of the present invention as characterized by Scanning Electron Microscopy (SEM) after being placed at 90 deg.C (left) and 130 deg.C (right) for 1 hour;
fig. 5 is a picture of the surface morphology of the PI composite LIB membrane prepared in the present invention, characterized by a Scanning Electron Microscope (SEM) after being left at 90 ℃ (left) and 130 ℃ (right) for 1 h.
Detailed Description
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.
The embodiment of the invention provides a composite lithium ion battery diaphragm which comprises a porous base layer diaphragm and a polyimide coating coated on one side of the porous base layer diaphragm. The embodiment provides a composite lithium ion battery diaphragm, which is formed by compounding a porous base diaphragm and a polyimide coating, integrates the advantages of two materials of polyolefin and polyimide, improves the compatibility of the polyolefin base diaphragm and the coating, improves the adhesive force of the polyolefin base diaphragm and the coating, improves the wettability of electrolyte, effectively improves the interface performance between a positive electrode, a negative electrode and the diaphragm, and improves the ionic conductivity and the cycle performance of an LIB battery, and meanwhile, the composite lithium ion battery diaphragm has good mechanical performance, and greatly improves the high temperature resistance of the lithium ion battery diaphragm.
In a preferred embodiment, the porous-based membrane is a membrane having a thickness of: 5-40 μm, porosity: 30-80% of polyolefin separator. In this example, specific requirements for the porous base layer separator are listed, wherein the thickness and porosity are limited, and the polyolefin separator in this form is compounded with the polyimide coating layer, so that the composite lithium electronic battery separator having the desired effect can be effectively obtained. In an alternative embodiment, a specific implementation form of the polyolefin separator is also listed, for example, the polyolefin separator may be one of a polyethylene lithium battery separator, a polypropylene lithium battery separator, or a composite separator with more than three layers, wherein the three layers are arranged at intervals (PP/PE/PP) between the polyethylene lithium battery separator and the polypropylene lithium battery separator.
In a preferred embodiment, the thickness of the polyimide coating is 1-10 μm, and the content of polyimide in the battery separator is 1-10%. The thickness of the polyimide coating and the content of the polyimide coating in the battery diaphragm are limited in the embodiment, so that the prepared battery diaphragm has good performance in the aspects of thickness, strength, air permeability and heat shrinkage. In an alternative embodiment, the thickness of the coating is specifically defined, and the molecular weight of the polyimide is further defined to be 10,000-300,000 Da. The polyimide coating under the condition is compounded with the porous base layer diaphragm to obtain the lithium ion battery diaphragm with expected effect.
The embodiment of the invention also provides a preparation method of the composite lithium ion battery diaphragm, which comprises the following steps:
and (3) synthesis of polyimide: adding dianhydride and diamine into a reaction vessel according to a molar ratio of 0.8-1.2 in a nitrogen environment, then adding an organic solvent, carrying out mechanical stirring reaction in an ice-water bath for 12-24h to obtain a polyamic acid solution, then adding acetic anhydride and triethylamine for chemical imidization, carrying out chemical imidization for 24-48h, precipitating the obtained polymer with ethanol, fully washing with ethanol and deionized water, placing in a drying oven, and drying at 60-120 ℃ overnight; vacuum drying at the temperature of 120-150 ℃ for 12-48h to obtain polyimide;
preparing a polyimide casting solution: according to the mass percentage concentration of 1-10%: 2-20%: 70-97% of the polyimide, the pore-forming agent and the organic solvent are mixed, and mechanically stirred in an oil bath at 50-100 ℃ until the mixture is uniformly mixed and completely dissolved, so as to obtain a polyimide casting solution;
preparing a composite lithium ion battery diaphragm: standing the obtained polyimide casting solution in an oil bath at 50-100 ℃ for 12-24h for defoaming, coating the polyimide casting solution on a porous base layer diaphragm, scraping the film by using a scraper, staying in the air for 3-300s, slowly and uniformly entering a coagulating bath containing a solvent and a non-solvent at room temperature for coagulation, washing the coagulated film with water, drying at 40-80 ℃ for 3-10h, and obtaining the composite lithium ion battery diaphragm after the water is completely volatilized.
In the embodiment, the preparation method of the composite lithium ion battery diaphragm is specifically provided, the battery diaphragm prepared by combining the method with specific parameter indexes can improve the compatibility of the polyolefin base diaphragm and the coating layer, improve the adhesive force of the polyolefin base diaphragm and the coating layer, improve the wettability of the electrolyte, effectively improve the interface performance between the positive electrode, the negative electrode and the diaphragm, improve the ionic conductivity and the cycle performance of the LIB battery, and meanwhile, the composite lithium ion battery diaphragm has good mechanical performance and greatly improves the high temperature resistance of the lithium ion battery diaphragm.
In an alternative embodiment, in order to prepare the battery separator with further better performance, some specific parameters of the above method can be optimized, for example, in the preparation step of the polyimide casting solution, the specific parameters can be calculated according to the mass percentage concentration of 4-8%: 8-12%: 80-88% of the synthesized polyimide, the pore-forming agent and the organic solvent are mixed. For example, in the preparation step of the composite lithium ion battery separator, the viscosity of the defoamed slurry is 40 to 800 centipoise, and preferably 60 to 600 centipoise. For example, when the polyimide casting solution is applied to the porous base separator, the application method may be dip-coating, spin-coating, dip-coating, doctor blade, wire bar, micro-gravure coating, or the like.
In an alternative embodiment, the dianhydride is a binary organic anhydride selected from one of biphenyl tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, pyromellitic dianhydride, oxydiphenyltetracarboxylic anhydride, and bisphenol a diether dianhydride; the diamine is organic diamine, and the organic diamine is selected from one of 4,4 '-diaminodiphenyl ether, 3, 4' -diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, 3 '-diphenyl sulfone diamine and 4, 4' -diphenyl sulfone diamine.
In an alternative embodiment, the organic solvent is one or a mixture of two selected from the group consisting of N-methylpyrrolidone, N-dimethylacetamide, N-dimethylformamide, dimethyl phthalate, dimethyl sulfoxide, m-cresol, tetrahydrofuran and methanol in any proportion; the pore-forming agent is selected from one or more of lithium chloride, sodium chloride, magnesium chloride, calcium carbonate, calcium chloride, methanol, ethanol, propanol, glycerol, acetone, acetic acid, tetrahydrofuran, polyethylene glycol with different molecular weights (molecular weight: 200-4000Da) and polyvinylpyrrolidone with different molecular weights.
In an alternative embodiment, the coagulation bath is a mixture of one or more organic solvents selected from DMAc, NMP, DMF, DMP, or ethanol and water, wherein the concentration of the organic solvent is 10-90%, preferably 20-80% by volume.
In the above examples, specific embodiments of dianhydride, diamine, organic solvent, pore-forming agent and coagulating bath are specifically listed, and it is understood that the above components are preferably, but not limited to, listed, and other components known to those skilled in the art may be equivalently substituted.
In order to more clearly and specifically describe the composite lithium ion battery separator and the preparation method thereof provided by the embodiments of the present invention, the following description will be made with reference to specific embodiments.
Example 1
Weighing 8.00g (0.04mol) of 4, 4' -diaminodiphenyl ether and 8.9g (0.0408mol) of pyromellitic dianhydride under a nitrogen environment, weighing 160mL of DMAC, adding into a reaction vessel, and mechanically stirring in an ice-water bath for 24 hours; then, 17.6mL of acetic anhydride and 24mL of triethylamine were added to the mixture, respectively, to perform chemical imidization. After 48h, precipitating the obtained polymer with ethanol, fully washing with ethanol and deionized water, placing in a drying oven for drying overnight at 100 ℃, and then vacuum-drying at 150 ℃ for 24h to obtain a light yellow PI product, wherein the light yellow PI product is shown in figure 1.
0.5g of the solid polyimide obtained above, 2.5g of PEG2000, 2.5g of polyvinylpyrrolidone (PVP) and 44.5g of DMAc were mixed, and mechanically stirred in an oil bath at 80 ℃ until the polyimide and the pore-forming agent were completely dissolved, to obtain a casting solution of PI. After the stirring was stopped, the mixture was defoamed in an oil bath at 80 ℃ for 60 min. Spreading a 16-micron PE (polyethylene) basement membrane flatly on a clean glass plate, pouring a proper amount of defoamed polyimide casting membrane solution on the PE basement membrane, scraping the membrane by using a scraper, slowly immersing the membrane in a DMAc (dimethyl formamide) coagulating bath (the volume ratio of DMAc to water is 3:2) at a constant speed after the membrane stays in the air for 1min to carry out NIPs (N-acetyl-N-methyl-pyrrolidone) membrane forming, removing the PE membrane with the polyimide after 3min, and taking out the PE membrane after the PE membrane is immersed in water for 12 h. The polyimide content in the prepared battery separator is 1%. After drying, the prepared composite lithium ion battery separator is tested for thickness, strength, air permeability value, thermal shrinkage and the like, and the results are shown in table 1.
Example 2
The types, the amounts and the process flow of the used materials are the same as those of the example 1, except that:
1g of the solid polyimide obtained above, 2.5g of PEG2000, 2.5g of PVP and 43g of DMAc are mixed, and mechanically stirred in an oil bath at the temperature of 80 ℃ until PI and the organic pore-forming agent are uniformly mixed and completely dissolved, so that P I casting solution is obtained. After the stirring was stopped, 60min was deaerated in an oil bath at 80 ℃. Spreading a 16-micron PE (polyethylene) basement membrane flatly on a clean glass plate, pouring a proper amount of defoamed polyimide film casting solution on the PE basement membrane, scraping the film by using a scraper, slowly immersing the film in a DMAc (dimethyl formamide) coagulating bath (the volume ratio of DMAc to water is 3:2) at a constant speed after the film stays in the air for 1min to carry out NIPs (N-acetyl-N-terminal-N) film formation, removing the PE basement membrane coated with polyimide after 3min, and soaking the PE basement membrane in deionized water for 12h and. The polyimide content of the prepared battery separator is 2%. The prepared composite lithium ion battery separator is tested for thickness, strength, air permeability value, thermal shrinkage and the like, and the results are shown in table 1.
Example 3
The types, the amounts and the process flow of the used materials are the same as those of the example 1, except that:
5g of the obtained solid polyimide, 2.5g of PEG2000, 2.5g of PVP and 40g of DMAc are mixed, and mechanically stirred in an oil bath at the temperature of 80 ℃ until the PI and the organic pore-forming agent are uniformly mixed and completely dissolved, so that a casting solution of the PI is obtained. After the stirring was stopped, the mixture was defoamed in an oil bath at 80 ℃ for 60 min. Spreading a 16-micron PE (polyethylene) basement membrane flatly on a clean glass plate, pouring a proper amount of defoamed polyimide film casting solution on the PE basement membrane, scraping the film by using a scraper, slowly immersing the film in a DMAc (dimethyl formamide) coagulating bath (the volume ratio of DMAc to water is 3:2) at a constant speed after the film stays in the air for 1min to carry out NIPs (N-acetyl-N-terminal-N) film formation, removing the PE basement membrane coated with polyimide after 3min, and soaking the PE basement membrane in deionized water for 12h and. The polyimide content of the prepared battery separator is 10%. The prepared composite lithium ion battery separator is tested for thickness, strength, air permeability value, thermal shrinkage and the like, and the results are shown in table 1.
Example 4
The types, the amounts and the process flow of the used materials are the same as those of the example 1, except that:
and (3) mixing 1g of the obtained solid polyimide, 5.0g of glycerol and 44g of DMAc, and mechanically stirring in an oil bath at the temperature of 80 ℃ until the PI and the organic small molecule pore-forming agent are uniformly mixed and completely dissolved to obtain the PI membrane casting solution. After the stirring was stopped, the mixture was allowed to stand and defoamed in an oil bath at 80 ℃ for 60 min. Spreading a 16-micron PE (polyethylene) basement membrane flatly on a clean glass plate, pouring a proper amount of defoamed polyimide film casting solution on the PE basement membrane, scraping the film by using a scraper, slowly immersing the film in a DMAc (dimethyl formamide) coagulating bath (the volume ratio of DMAc to water is 3:2) at a constant speed after the film stays in the air for 1min to carry out NIPs (N-acetyl-N-methyl-pyrrolidone) film forming, removing the PE basement membrane coated with the polyimide after 3min, and taking out the PE basement membrane after the PE basement membrane is immersed in deionized water for 12 h. The polyimide content of the prepared battery separator is 2%. The prepared composite lithium ion battery separator is tested for thickness, strength, air permeability value, thermal shrinkage and the like, and the results are shown in table 1.
Example 5
The types, the amounts and the process flow of the used materials are the same as those of the example 1, except that:
1g of the solid polyimide obtained above, 2.5g of PEG2000, 2.5g of PVP and 44g of DMAc are mixed, and mechanically stirred in an oil bath at the temperature of 80 ℃ until the polyimide and the pore-forming agent are uniformly mixed and completely dissolved, so that a polyimide casting solution is obtained. After the stirring was stopped, the mixture was defoamed in an oil bath at 80 ℃ for 60 min. Spreading a 16-micron PE (polyethylene) base film on a clean glass plate flatly, pouring a proper amount of defoamed film casting liquid on the PE base film, scraping the film by using a scraper, staying in the air for 1min, slowly and uniformly immersing in a DMAc (DMAc and water volume ratio is 2:3) at room temperature to form a film, removing the polyimide-coated PE film after 3min, immersing in water for 12h, and taking out. The polyimide content of the prepared battery separator is 2%. The prepared composite lithium ion battery separator is tested for thickness, strength, air permeability value, thermal shrinkage and the like, and the results are shown in table 1.
Example 6
The types, the amounts and the process flow of the used materials are the same as those of the example 1, except that:
1g of the solid polyimide obtained above, 2.5g of PEG2000, 2.5g of PVP and 44g of DMAc are mixed, and mechanically stirred in an oil bath at the temperature of 80 ℃ until the polyimide and the pore-forming agent are completely dissolved, so that a PI membrane casting solution is obtained. After the stirring was stopped, the mixture was allowed to stand and defoamed in an oil bath at 80 ℃ for 60 min. Spreading a 16-micron PE (polyethylene) base film on a clean glass plate flatly, pouring a proper amount of defoamed polyimide film casting solution on the PE base film, scraping the film by using a scraper, slowly and uniformly immersing the PE base film in a DMAc (dimethyl formamide) coagulating bath (the volume ratio of DMAc to water is 2:3) at room temperature to form a film after the PE base film stays in the air for 30s, removing the PE film coated with the polyimide after 1min, immersing the PE base film in tap water, overflowing for 24h, and taking out. The polyimide content of the prepared battery separator is 2%. The prepared composite lithium ion battery separator is tested for thickness, strength, air permeability value, thermal shrinkage and the like, and the results are shown in table 1.
Comparative example 1
The same procedure as in example 1 was followed, except that the battery separator was composed of only a 12 μm PE-based film, and then the thickness, strength, air permeability value, and heat shrinkability were measured, and the results are shown in table 1.
Comparative example 2
The same procedure as in example 1, except that the battery separator was composed of only 18 μm celgard base film, and then the thickness, strength, air permeability, and heat shrinkability were measured, the results of which are shown in table 1.
Comparative example 3
The same procedure as in example 1, except that the battery separator was composed of only a 22 μm PP-based film, and then thickness, strength, air permeability, and heat shrinkability were measured, the results of which are shown in table 1.
Comparative example 4
The same materials, amounts and process flow as those used in example 1 were used, and the thickness, strength, air permeability and heat shrinkability were measured under the same conditions, except that 18 μm celgard was used as the base film, and the results are shown in table 1.
Comparative example 5
The same materials, amounts and processes as those used in example 1 were used, and tests of thickness, strength, air permeability and heat shrinkability were conducted under the same conditions, except that 22 μm PP was used as the base film, and the results are shown in Table 1.
Table 1 results of performance index test of battery separators provided in examples 1 to 6 and comparative examples 1 to 5 described above
As can be seen from the data in table 1, the composite lithium ion battery separator provided by the present application has good properties in terms of thickness, tensile strength, air permeability, heat shrinkability, etc., as can be seen from fig. 4 and 5, the PI composite LIB separator prepared by the present invention has substantially no change in pore structure after being placed at 90 ℃ or 130 ℃ for 1 hour; after the PE base film is placed at 90 ℃ for 1h, the surface pore structure is not damaged; however, after being placed at 130 ℃ for 1h, the pore structure of the membrane is obviously changed, and a large part of pores are closed. Meanwhile, the battery separator in the application also has a smaller contact angle, as shown in fig. 2 and 3, the contact angle of the Celgard polypropylene LIB separator to the electrolyte is 51.4 °, and the contact angle of the composite LIB separator coated with polyimide with the solid content of 2% to the electrolyte is reduced to 29.1 °. Compared with a polyolefin base film, the wetting property of the composite LIB diaphragm prepared by coating PI on the surface of the base film to electrolyte is greatly improved. In conclusion, the PI composite LIB diaphragm prepared by the NIPs has better thermal stability and good wettability to electrolyte, and the LIB taking the PI composite LIB diaphragm as the diaphragm has better battery cycle performance.
Claims (11)
1. The composite lithium ion battery separator is characterized by comprising a porous base layer separator and a polyimide coating coated on one side of the porous base layer separator;
the membrane is prepared by the following steps:
and (3) synthesis of polyimide: adding dianhydride and diamine into a reaction vessel according to a molar ratio of 0.8-1.2 in a nitrogen environment, then adding an organic solvent, carrying out mechanical stirring reaction in an ice-water bath for 12-24h to obtain a polyamic acid solution, then adding acetic anhydride and triethylamine for chemical imidization, carrying out chemical imidization for 24-48h, precipitating the obtained polymer with ethanol, fully washing with ethanol and deionized water, placing in a drying oven, and drying at 60-120 ℃ overnight; vacuum drying at the temperature of 120-150 ℃ for 12-48h to obtain polyimide;
preparing a polyimide casting solution: according to the mass percentage concentration of 1-10%: 2-20%: 70-97% of the polyimide, the pore-forming agent and the organic solvent are mixed, and mechanically stirred in an oil bath at 50-100 ℃ until the mixture is uniformly mixed and completely dissolved, so as to obtain a polyimide casting solution;
preparing a composite lithium ion battery diaphragm: standing the obtained polyimide casting solution in an oil bath at 50-100 ℃ for 12-24h for defoaming, coating the polyimide casting solution on a porous base layer diaphragm, scraping the film by using a scraper, staying in the air for 3-300s, slowly and uniformly entering a coagulating bath containing a solvent and a non-solvent at room temperature for coagulation, washing the coagulated film with water, drying at 40-80 ℃ for 3-10h, and obtaining a composite lithium ion battery diaphragm after water is completely volatilized;
the pore-forming agent is selected from one or more of lithium chloride, sodium chloride, magnesium chloride, calcium carbonate, calcium chloride, methanol, ethanol, propanol, glycerol, acetone, acetic acid, tetrahydrofuran, polyethylene glycol with different molecular weights and polyvinylpyrrolidone with different molecular weights.
2. The composite lithium ion battery separator according to claim 1, wherein the porous base layer separator is a porous base layer separator having a thickness of: 5-40 μm, porosity: 30-80% of polyolefin separator.
3. The composite lithium ion battery separator according to claim 2, wherein the polyolefin separator is one selected from a polyethylene lithium battery separator, a polypropylene lithium battery separator, and three or more layers of composite separators arranged at intervals between the polyethylene lithium battery separator and the polypropylene lithium battery separator.
4. The composite lithium ion battery separator according to claim 1, wherein the thickness of the polyimide coating is 1-10 μm, and the polyimide content in the battery separator is 1-10%.
5. The composite lithium ion battery separator according to claim 1, wherein in the step of preparing the polyimide casting solution, the polyimide casting solution is prepared by mixing the following components in percentage by mass at 4-8%: 8-12%: 80-88% of the synthesized polyimide, the pore-forming agent and the organic solvent are mixed.
6. The composite lithium ion battery separator according to claim 1, wherein in the step of preparing the composite lithium ion battery separator, the viscosity of the defoamed slurry is 40 to 800 centipoise.
7. The composite lithium ion battery separator according to claim 6, wherein the viscosity of the defoamed slurry is 60 to 600 centipoise.
8. The composite lithium ion battery separator according to claim 1, wherein the coagulation bath is a mixture of one or more organic solvents selected from DMAc, NMP, DMF, DMP, or ethanol and water, which is a non-solvent, wherein the concentration of the organic solvent is 10-90% by volume.
9. The composite lithium ion battery separator according to claim 8, wherein the volume percent concentration of the organic solvent is 20-80%.
10. The composite lithium ion battery separator according to claim 1, wherein the dianhydride is a binary organic anhydride selected from one of biphenyl tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, pyromellitic dianhydride, oxydiphenyltetracarboxylic anhydride, and bisphenol a diether dianhydride; the diamine is organic diamine, and the organic diamine is selected from one of 4,4 '-diaminodiphenyl ether, 3, 4' -diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, 3 '-diphenyl sulfone diamine and 4, 4' -diphenyl sulfone diamine.
11. The composite lithium ion battery separator according to claim 1, wherein the organic solvent is one or a mixture of two selected from the group consisting of N-methylpyrrolidone, N-dimethylacetamide, N-dimethylformamide, dimethyl phthalate, dimethyl sulfoxide, m-cresol, tetrahydrofuran, and methanol at any ratio.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810095512.9A CN108346765B (en) | 2018-01-31 | 2018-01-31 | Composite lithium ion battery diaphragm and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810095512.9A CN108346765B (en) | 2018-01-31 | 2018-01-31 | Composite lithium ion battery diaphragm and preparation method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108346765A CN108346765A (en) | 2018-07-31 |
| CN108346765B true CN108346765B (en) | 2020-02-18 |
Family
ID=62960996
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810095512.9A Active CN108346765B (en) | 2018-01-31 | 2018-01-31 | Composite lithium ion battery diaphragm and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108346765B (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109004165B (en) * | 2018-08-01 | 2021-10-26 | 上海钱丰纺织品有限公司 | Heat-resistant lithium ion battery diaphragm and preparation method thereof |
| CN109817870B (en) * | 2018-12-29 | 2020-06-05 | 东莞东阳光科研发有限公司 | Polyimide microsphere slurry, composite diaphragm and lithium ion battery |
| WO2020142708A1 (en) * | 2019-01-04 | 2020-07-09 | Celgard, Llc | Polyimide coated separator for lithium batteries or capacitor |
| CN110142189A (en) * | 2019-04-08 | 2019-08-20 | 深圳市劢全新材料科技有限责任公司 | A kind of coating method and its application in high-temperaure coating coating |
| CN110474009A (en) * | 2019-07-12 | 2019-11-19 | 大连恒超锂业科技有限公司 | A kind of lithium ion battery nonwoven fabric base composite diaphragm and preparation method thereof |
| CN111063852A (en) * | 2019-09-17 | 2020-04-24 | 宁德时代新能源科技股份有限公司 | Separator, method for producing same, lithium ion secondary battery, and device |
| CN110911615A (en) * | 2019-11-20 | 2020-03-24 | 芜湖天弋能源科技有限公司 | High-temperature-resistant lithium ion battery diaphragm, preparation method thereof and lithium ion battery prepared from high-temperature-resistant lithium ion battery diaphragm |
| CN113131089A (en) * | 2019-12-30 | 2021-07-16 | 深圳市研一新材料有限责任公司 | Spider-web structure lithium ion battery diaphragm and preparation method thereof |
| CN111234224A (en) * | 2020-01-16 | 2020-06-05 | 青岛蓝科途膜材料有限公司 | Modified aramid polymer with polyimide structure, aramid film casting liquid, lithium battery diaphragm, preparation method of lithium battery diaphragm and lithium battery |
| CN112803118B (en) * | 2021-01-13 | 2022-09-09 | 山东工业陶瓷研究设计院有限公司 | Battery separator, preparation method and polyimide porous membrane impregnation equipment |
| CN113488739B (en) * | 2021-08-03 | 2023-03-10 | 广东工业大学 | Three-layer porous diaphragm combining electrostatic spinning and phase separation method and preparation method and application thereof |
| CN114204210B (en) * | 2021-11-05 | 2024-01-05 | 东方电气集团科学技术研究院有限公司 | Preparation method of sodium ion battery diaphragm |
| CN114709558A (en) * | 2022-03-25 | 2022-07-05 | 中材锂膜有限公司 | High-heat-resistance polyamide-imide composite diaphragm and preparation method thereof |
| CN115332722A (en) * | 2022-08-16 | 2022-11-11 | 合肥国轩高科动力能源有限公司 | Modified high-heat-resistance polyamide coating diaphragm and preparation method and application thereof |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4838900A (en) * | 1988-04-13 | 1989-06-13 | E. I. Du Pont De Nemours And Company | Polyimide gas separation membranes |
| CN101343362B (en) * | 2008-09-03 | 2011-11-16 | 中国科学院化学研究所 | Polyimide resin, its midbody, preparation method and application thereof |
| CN103127846B (en) * | 2013-03-15 | 2016-05-18 | 中国石油大学(华东) | A kind of asymmetric polyimide film for separating of methyl cyclopentadiene and cyclopentadiene |
| CN103531736B (en) * | 2013-10-27 | 2016-08-24 | 乐凯胶片股份有限公司 | A kind of high heat-resisting lithium ion battery separator and preparation method thereof |
-
2018
- 2018-01-31 CN CN201810095512.9A patent/CN108346765B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN108346765A (en) | 2018-07-31 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108346765B (en) | Composite lithium ion battery diaphragm and preparation method thereof | |
| CN107240663B (en) | Polymer coating diaphragm and preparation method thereof | |
| WO2018218984A1 (en) | High temperature-resistant aramid lithium-ion battery composite separator and manufacturing method therefor | |
| Wang et al. | Preparation of thermal stable porous polyimide membranes by phase inversion process for lithium-ion battery | |
| CN106025149A (en) | High-temperature-resistant composite lithium battery diaphragm and preparation method for same | |
| CN108365151A (en) | A kind of polyimide high temperature-resistant lithium battery diaphragm and preparation method thereof | |
| Lin et al. | Mechanically robust, nonflammable and surface cross-linking composite membranes with high wettability for dendrite-proof and high-safety lithium-ion batteries | |
| CN109119572A (en) | Polyimides lithium battery diaphragm and preparation method thereof and lithium battery comprising the diaphragm | |
| CN105552278A (en) | Preparation method of polyamide-imide lithium battery membrane | |
| WO2017211126A1 (en) | Polymer electrolyte membrane and method for preparing same | |
| CN108807818B (en) | Aromatic polyamide composite diaphragm and preparation method thereof | |
| CN110828750A (en) | Porous polyimide film, preparation method thereof and lithium ion battery | |
| CN112216928A (en) | Modified composite heat-resistant lithium ion battery diaphragm and preparation method thereof | |
| CN106229445A (en) | A kind of lithium ion battery separator and preparation method thereof and lithium ion battery | |
| KR20190126012A (en) | Polymer electrolyte membranes, membrane electrode assemblies, and solid polymer fuel cells | |
| CN111234278A (en) | Porous polyimide film and preparation method thereof | |
| CN110938228B (en) | Preparation method and application of zeolite/polyimide composite membrane | |
| Zhang et al. | Highly thermostable expanded polytetrafluoroethylene separator with mussel-inspired silica coating for advanced Li-ion batteries | |
| CN113381122A (en) | Method for preparing porous meta-aramid diaphragm by non-solvent induced phase separation method | |
| KR20150036701A (en) | High temperature melt integrity separator | |
| CN110752337A (en) | Composite diaphragm, preparation method and application thereof | |
| Li et al. | Crystalline Al 2 O 3 modified porous poly (aryl ether ketone)(PAEK) composite separators for high performance lithium-ion batteries via an electrospinning technique | |
| KR101296109B1 (en) | Menufacturing Method of Meta-Aramid Based Porous Membrane for Secondary Battery and Porous Membrane thereby | |
| CN115693021A (en) | Polyimide fiber/aerogel composite membrane and preparation method thereof | |
| CN114709558A (en) | High-heat-resistance polyamide-imide composite diaphragm and preparation method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |