CN116247382A - Clean high-adhesion-performance lithium battery composite diaphragm and preparation method thereof - Google Patents

Clean high-adhesion-performance lithium battery composite diaphragm and preparation method thereof Download PDF

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CN116247382A
CN116247382A CN202310472578.6A CN202310472578A CN116247382A CN 116247382 A CN116247382 A CN 116247382A CN 202310472578 A CN202310472578 A CN 202310472578A CN 116247382 A CN116247382 A CN 116247382A
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adhesive
lithium battery
adhesion
clean high
boehmite
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贺金梅
刘兴原
白永平
程凤
黄玉东
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Harbin Institute of Technology
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Harbin Institute of Technology
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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
    • 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
    • H01M50/403—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
    • 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
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/423—Polyamide resins
    • 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
    • H01M50/434—Ceramics
    • 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
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • 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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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Composite Materials (AREA)
  • Ceramic Engineering (AREA)
  • Cell Separators (AREA)

Abstract

A clean high-adhesion lithium battery composite diaphragm and a preparation method thereof. The two-component polyurethane is used as an adhesive, the thermoplastic polyurethane is used as a thickener and an adhesive, the boehmite is used as a filler, and the pollution-free and low-toxicity solvent butyl acetate is added and then the coating is carried out. The TDI of polyurethane and polyol are utilized to react and crosslink to provide adhesion, a large amount of voids provided by BH are utilized to enhance the porosity of the coating, then thermoplastic polyurethane is utilized to enhance the initial viscosity of casting solution, so that the initial small molecule bi-component polyurethane can not permeate into the surface of the microporous membrane, and finally hydroxyl functional groups rich in BH surface are utilized to enhance the lyophilicity of the coating to electrolyte. The composite diaphragm solves the problems of environmental pollution, poor binding force of water-based adhesive and the like of the traditional oily adhesive diaphragm by introducing bi-component polyurethane, and solves the problem of serious powder falling caused by small molecules penetrating into micropores at the beginning by taking thermoplastic polyurethane as a thickener.

Description

Clean high-adhesion-performance lithium battery composite diaphragm and preparation method thereof
Technical Field
The invention belongs to the field of lithium ion batteries, and particularly relates to a clean high-adhesion-performance lithium battery composite diaphragm and a preparation method thereof.
Background
With the continuous popularization of electric automobiles, the use frequency of lithium ion batteries is increased, and the requirements on the safety performance and the electrochemical performance of the batteries are also increased. The lithium ion battery has the advantages of high working voltage, high energy density, good cycle performance, small self-discharge, no memory effect, wide working temperature range and the like. The lithium ion battery mainly comprises an anode, a cathode, electrolyte and a diaphragm. The diaphragm is used as a crucial part in the composition of the lithium ion battery, and the function of the diaphragm is embodied in isolating the anode and the cathode of the battery to prevent the direct contact short circuit of the anode and the cathode; and the lithium ion battery is used as a channel for lithium ion transmission, so that lithium ions can continuously shuttle and swing between the positive chamber and the negative chamber. The separator plays a very important role in the safety performance of the battery, for example, under the environment of high temperature and the like, the separator is thermally contracted to cause the positive electrode and the negative electrode to be directly contacted with short circuit to release heat, so that the internal temperature of the battery is increased, and the thermal runaway reaction further occurs, thereby causing severe damages such as explosion combustion and the like. Thus, the separator plays an irreplaceable role in the lithium ion battery assembly.
The lithium ion battery diaphragm commonly used in the market at present is generally a polyolefin diaphragm, and the diaphragm has the advantages of stable chemical structure, excellent mechanical strength, good electrochemical performance and the like. Commercial separators are mainly Polyethylene (PE) or polypropylene (PP) single-layer microporous separators, PP/PE/PP multilayer composite microporous films and ceramic composite separators. The single-layer microporous membrane has poor thermal stability, and when the membrane reaches a certain temperature, serious thermal shrinkage occurs to lead the anode and the cathode to be in direct contact, so that a large amount of heat is generated, and finally, the battery is disabled due to thermal runaway. Although the PP/PE/PP multilayer composite microporous membrane has a thermal shutdown function, due to the limitation of the melting temperature of the PP substrate, severe thermal shrinkage occurs in the range of 155-165 ℃ so as to cause the failure of the battery. The ceramic composite diaphragm has excellent heat stability and can keep the initial shape at high temperature without shrinkage, but the common adhesive of the ceramic composite diaphragm is oily adhesive, and the adhesive has good bonding strength but serious pollution. However, the use of an environment-friendly aqueous adhesive has the fatal disadvantage of insufficient adhesive strength.
Disclosure of Invention
The invention aims to solve the problems that an oil-soluble binder used for a ceramic composite diaphragm has pollution, a water-soluble binder has weak bonding strength and the like, and provides a clean high-bonding-performance lithium battery composite diaphragm and a preparation method thereof.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the clean high-adhesion-performance lithium battery composite diaphragm comprises a base film and a coating, wherein the coating comprises, by mass, 70% -90% of boehmite, 1% -3% of a coupling agent and 10% -30% of an adhesive; the adhesive consists of thermoplastic polyurethane and bi-component polyurethane, wherein the mass ratio of the thermoplastic polyurethane to the adhesive is controlled to be 50-80%, and the bi-component polyurethane is obtained by polymerizing polyisocyanate and polyol. According to the proportion, the obtained diaphragm has strong bonding strength, high lyophilic property, strong electrolyte resistance and clean high bonding property, and the diaphragm is obtained by coating the casting solution on the base film, and the thickness of the finally obtained diaphragm is not more than 25 mu m.
Further, the boehmite has a particle size of 200-500nm and a layered lattice structure (see FIG. 6), and the structure contains crystal water as a main precursor for industrial production of alumina, al having a higher hardness than that of the particles 2 O 3 Boehmite is a lighter, softer, cheaper inorganic ceramic filler than Al 2 O 3 The boehmite has the advantages of better dispersibility, high interfacial free energy, large specific surface area and easiness in forming pores among the boehmite.
Further, the polyisocyanate is one or more of diphenylmethane diisocyanate (MDI), toluene Diisocyanate (TDI), polymeric MDI (PAPI); the degree of polymerization of the polyisocyanate is 2-6; the polyalcohol is one or more of polyoxypropylene glycol (PPG), glycerol random polyether (GPE-3000) and propylene glycol block polyether (L35); the functionality of the polyol is 2-3.5.
Further, the mass ratio of the polyisocyanate to the polyol is 1 to 1.2:1.
further, the coupling agent is one or more of KH550, KH560 and KH 570.
The preparation method of the clean high-adhesion lithium battery composite diaphragm comprises the following steps:
step one: mixing boehmite, a coupling agent and alcohol, uniformly stirring, reacting for 1-2 hours in a water bath at 70-80 ℃ and at a stirring speed of 500-800rpm, then ultrasonically cleaning for 3-5 times, and finally drying the modified boehmite in a drying oven at 80-100 ℃ for 1 hour;
step two: mixing boehmite obtained in the first step with polyol in the bi-component polyurethane and thermoplastic polyurethane, adding a solvent, and stirring for 0.5-1h under the conditions of water bath at 40 ℃ and 300-500rpm to obtain a mixture in which the thermoplastic polyurethane is completely dissolved;
step three: adding polyisocyanate into the mixture obtained in the step two, and continuously stirring for 10-15min under the conditions of water bath at 40 ℃ and 300-500rpm to obtain a mixture with initial crosslinking degree;
step four: and (3) spreading the mixture obtained in the step (III) on a base film by using a bar coater, and then putting the base film into an oven for curing.
Further, in the second step, the boehmite to solvent ratio is 1:1.3-1.5.
Further, in the second step, the solvent is one or more of butyl acetate, ethyl acetate and n-propyl acetate.
Further, in the fourth step, the curing temperature is 60-80 ℃ and the curing time is 2-3h. The thickness of the coating layer of the diaphragm is 6-16 mu m, the thickness of the base film is generally 9-16 mu m, and the total thickness of the diaphragm is not more than 25 mu m after the thickness of the coating layer is added.
Further, the specification of the bar coater is 12-20 mu m, the base film is one or more of PE, PP, PET and a composite film thereof, the base film is ultrasonically cleaned for 3 times by absolute ethyl alcohol for 10 minutes each time, and finally the drying temperature is 50 ℃ and the drying time is 0.5h.
Compared with the prior art, the invention has the beneficial effects that:
(1) In the invention, the bi-component polyurethane is used as the adhesive, and compared with the aqueous adhesives such as aqueous polyurethane, polyvinyl alcohol and the like, the cross-linked network formed by isocyanate groups and hydroxyl groups of the bi-component polyurethane can bond boehmite on the surface of the base film well, so that the coating has excellent electrolyte resistance and bonding strength. Compared with other organic solvents such as NMP, DMAC, DMF, the organic solvent has the advantages of environment friendliness due to the fact that low-toxicity and volatile butyl acetate is used as the solvent.
(2) The added inorganic ceramic boehmite has high interfacial free energy, large specific surface area, easy formation of gaps between boehmite and existence of a large number of hydroxyl groups on the surface, so that the lyophilic property of the coating is well improved.
(3) The viscosity of the system can be increased by adding the thickener thermoplastic polyurethane, and the initial low-molecular bi-component polyurethane can not permeate into micropores of the diaphragm to have a crosslinking and bonding effect, so that the problem of serious powder falling of high-proportion boehmite is solved. The composite film coated by the bi-component polyurethane mixed boehmite has the advantages of environmental protection, good bonding performance, good electrolyte resistance and the like, and is expected to be widely applied to the field of commercial lithium ion batteries.
Drawings
FIG. 1 is a graph showing the bonding strength of a composite film with different proportions of thermoplastic polyurethane to colloid in the examples;
FIG. 2 is a graph showing the adhesive strength of the composite film at different proportions of thermoplastic polyurethane to colloid in the comparative example;
FIG. 3 is a schematic view of electrolyte resistance of the composite film in examples with different proportions of thermoplastic polyurethane to colloid;
FIG. 4 is a schematic view of electrolyte resistance of the composite film in comparative examples with different amounts of thermoplastic polyurethane;
FIG. 5 is a schematic view of the lyophilicity of a composite film with varying proportions of Thermoplastic Polyurethane (TPU) to colloid;
FIG. 6 is a graph of boehmite microtopography of a composite membrane surface.
Detailed Description
The following further describes the technical scheme of the present invention according to the drawings and the embodiments, but is not limited thereto, and all modifications and equivalents of the technical scheme of the present invention are included in the scope of the present invention without departing from the scope of the technical scheme of the present invention.
In the invention, bi-component polyurethane is used as an adhesive, thermoplastic polyurethane is used as a thickener and an adhesive, boehmite is used as a filler, and a pollution-free and low-toxicity solvent butyl acetate is added and then the coating is carried out. The TDI of polyurethane and polyol are utilized to react and crosslink to provide adhesion, a large amount of voids provided by BH are utilized to enhance the porosity of the coating, then thermoplastic polyurethane is utilized to enhance the initial viscosity of casting solution, so that the initial small molecule bi-component polyurethane can not permeate into the surface of the microporous membrane, and finally hydroxyl functional groups rich in BH surface are utilized to enhance the lyophilicity of the coating to electrolyte. The composite diaphragm solves the problems of environmental pollution, poor binding force of water-based adhesive and the like of the traditional oily adhesive diaphragm by introducing bi-component polyurethane, and solves the problem of serious powder falling caused by small molecules penetrating into micropores at the beginning by taking thermoplastic polyurethane as a thickener. The composite film has good bonding strength, electrolyte resistance and lyophilic property, thereby expanding the application field of polyurethane.
Example 1:
the preparation method comprises the following steps of:
step one: chemical modification treatment is carried out on boehmite, 99 parts of boehmite, 1 part of coupling agent KH550 and 200 parts of alcohol are mixed, uniformly stirred and then reacted for 2 hours in a water bath at 80 ℃ and at a stirring speed of 500rpm, then ultrasonic cleaning is carried out for multiple times, and finally the modified boehmite is put into a baking oven at 100 ℃ for drying for 1 hour; treatment with KH550 is mainly because boehmite surface has a large number of hydroxyl groups, KH550 can react with hydroxyl groups to modify boehmite. The modified boehmite has better adhesion with the adhesive polyurethane.
Step two: and (3) mixing 80 parts of modified boehmite with 20 parts of adhesive, wherein the proportion of thermoplastic polyurethane in 20 parts of adhesive to the two-component polyurethane is 0.5, and the proportion of isocyanate groups to hydroxyl groups in the two-component polyurethane is 1.2:1. Firstly, mixing boehmite with hydroxyl components in the two-component polyurethane and thermoplastic polyurethane, adding 125 parts of butyl acetate, and stirring for 0.5h under the conditions of water bath at 40 ℃ and 300rpm to dissolve the thermoplastic polyurethane.
Step three: the isocyanate-based component of the two-component polyurethane was added to the mixture obtained in step two and stirred for 10min still in a water bath at 40℃and 300rpm to give an initial degree of crosslinking.
Step four: and (3) scraping the mixture obtained in the step (III) on a polyethylene film by using a bar coater to obtain a composite film with the thickness of 8-18 mu m, and then curing the composite film in a 60 ℃ oven for 3 hours.
Example 2:
this example differs from example 1 in that in step two, the 20 parts of adhesive thermoplastic polyurethane make up a ratio of 0.6 of the two-component polyurethane to itself.
Example 3:
this example differs from example 1 in that in step two, the 20 parts of adhesive thermoplastic polyurethane make up a ratio of 0.8 of the two-component polyurethane to itself.
Example 4:
this example differs from example 1 in that in step two, the 20 parts of adhesive thermoplastic polyurethane make up 1.0 of the two-component polyurethane to itself.
Example 5:
this example differs from example 1 in that in step two, the 20 parts of adhesive thermoplastic polyurethane make up a ratio of 0.1 of the two-component polyurethane to itself.
Example 6:
this example differs from example 1 in that in step two, the 20 parts of adhesive thermoplastic polyurethane make up a ratio of 0.3 of the two-component polyurethane to itself.
Comparative example 1:
this example differs from example 1 in that no thickener thermoplastic polyurethane was added.
Comparative example 2:
this example differs from example 1 in that no thickener is added and that a two-component polyurethane is used which has a ratio of 0.3 to boehmite.
Comparative example 3:
this example differs from example 1 in that the binder used is oil-soluble PVDF, the diluent is NMP, and no thickener is added.
The test results obtained for the examples and comparative examples are as follows:
the adhesive strength test is carried out on the prepared composite film by using the adhesive tape, as shown in fig. 1 and 2, the experimental result is that when the thermoplastic polyurethane accounts for 0.5-0.8 of the total adhesive, the adhesive performance is good, only a small amount of boehmite on the surface of the adhesive tape drops off, and the surface of the composite film after the adhesive tape treatment is complete; the thermoplastic polyurethane accounts for 1.0 of the total adhesive, namely when the adhesive is thermoplastic polyurethane, the adhesive performance is poor, more boehmite is stripped from the surface of the adhesive tape, and the surface of the composite film after the adhesive tape treatment is complete. And when the proportion of the thickener is reduced to less than 0.5 of the colloid amount, the powder falling phenomenon is serious. In comparative examples 1 and 2, in which no thickener was added, the powder falling phenomenon was also more serious than in the examples in which a thickener was added. In comparative example 3, PVDF is an oil-soluble adhesive, so that it has a better powder falling phenomenon than that of the two-component polyurethane, but the two-component polyurethane when a proper amount of thickener is added has a little different adhesive strength from that of the two-component polyurethane. According to the data, no matter what proportion the thermoplastic polyurethane is adjusted in the adhesive, the adhesive strength of the adhesive tends to be increased and then decreased with the increase of the thermoplastic polyurethane content, and the adhesive effect between the coating and the base film is best when the thickener thermoplastic polyurethane accounts for 0.5-0.8 of the colloid.
The prepared composite film is soaked in electrolyte for 72 hours, the surface morphology of the electrolyte before and after soaking is observed, as shown in fig. 3 and 4, and the experimental result shows that when 80% of boehmite in the composite film is obtained, the surface morphology is complete when the thickener thermoplastic polyurethane accounts for 0.5-0.8 of the colloid, and the excellent electrolyte resistance is reflected. In the previous studies, the prepared two-component polyurethane composite film cannot have good adhesive strength under the condition of meeting the electrolyte resistance performance under the condition of high boehmite filling amount.
The contact angle between the diaphragm and the electrolyte is tested by using an electrostatic contact angle tester, the test result is shown in figure 5, the test result shows that the contact angle between all diaphragms and the electrolyte is close to 0 degrees, the contact angle between the PE base film and the electrolyte is 48 degrees, and the addition of boehmite proves that the lyophilic property of the composite film is successfully improved, so that the composite film has excellent lyophilic property.
The strength of the bonding strength of the composite film can influence the specific charge and discharge capacity, coulomb efficiency and polarization degree in the cycling process of the lithium ion battery. The composite film with weak bonding strength can gradually drop in the charge and discharge process, so that the physical and chemical properties of the composite film are poor, the polarization degree of the lithium ion battery is increased, and the cycle service life of the lithium ion battery is seriously attenuated. Therefore, the composite film prepared by the invention improves the bonding strength, thereby avoiding the problem of increased polarization degree caused by coating falling in the charge-discharge process, further prolonging the cycle service life of the lithium ion battery, and avoiding the separator from participating in the charge-discharge reaction in the battery in the cycle process, so that the integrity of the composite film can be maintained in the cycle process. The strength of the lyophilic property of the separator affects the lithium ion migration number of the separator, and the lithium ion migration number of the separator having poor lyophilic property is low, and thus the capacity, the rate performance, and the like of the separator are poor. The separator with good lyophilic property is often used in the field of batteries requiring high capacity and high rate because it can improve the mobility of lithium ions. The prepared composite film has good application prospect.

Claims (10)

1. The utility model provides a clean high adhesive property lithium electricity composite membrane which characterized in that: the diaphragm comprises a base film and a coating, wherein the coating comprises, by mass, 70% -90% of boehmite, 1% -3% of a coupling agent and 10% -30% of an adhesive; the adhesive consists of thermoplastic polyurethane and bi-component polyurethane, wherein the mass ratio of the thermoplastic polyurethane to the adhesive is controlled to be 50-80%, and the bi-component polyurethane is obtained by polymerizing polyisocyanate and polyol.
2. The clean high-adhesion lithium battery composite diaphragm according to claim 1, wherein: the boehmite has a particle size of 200-500nm and a layered lattice structure.
3. The clean high-adhesion lithium battery composite diaphragm according to claim 1, wherein: the polyisocyanate is one or more of diphenylmethane diisocyanate (MDI), toluene Diisocyanate (TDI) and polymeric MDI (PAPI); the degree of polymerization of the polyisocyanate is 2-6; the polyalcohol is one or more of polyoxypropylene glycol (PPG), glycerol random polyether (GPE-3000) and propylene glycol block polyether (L35); the functionality of the polyol is 2-3.5.
4. A clean high adhesion performance lithium battery composite separator according to claim 1 or 3, characterized in that: the mass ratio of the polyisocyanate to the polyol is 1-1.2:1.
5. the clean high-adhesion lithium battery composite diaphragm according to claim 1, wherein: the coupling agent is one or more of KH550, KH560 and KH 570.
6. A method for preparing the clean high-adhesion lithium battery composite diaphragm according to claims 1-5, which is characterized in that: the method comprises the following steps:
step one: mixing boehmite, a coupling agent and alcohol, uniformly stirring, reacting for 1-2 hours in a water bath at 70-80 ℃ and at a stirring speed of 500-800rpm, then ultrasonically cleaning for 3-5 times, and finally drying the modified boehmite in a drying oven at 80-100 ℃ for 1 hour;
step two: mixing boehmite obtained in the first step with polyol in the bi-component polyurethane and thermoplastic polyurethane, adding a solvent, and stirring for 0.5-1h under the conditions of water bath at 40 ℃ and 300-500rpm to obtain a mixture in which the thermoplastic polyurethane is completely dissolved;
step three: adding polyisocyanate into the mixture obtained in the step two, and continuously stirring for 10-15min under the conditions of water bath at 40 ℃ and 300-500rpm to obtain a mixture with initial crosslinking degree;
step four: and (3) spreading the mixture obtained in the step (III) on a base film by using a bar coater, and then putting the base film into an oven for curing.
7. The method for preparing the clean high-adhesion lithium battery composite diaphragm, which is disclosed in claim 6, is characterized in that: in the second step, the ratio of boehmite to solvent is 1:1.3-1.5.
8. The method for preparing the clean high-adhesion lithium battery composite diaphragm, which is disclosed in claim 6, is characterized in that: in the second step, the solvent is one or more of butyl acetate, ethyl acetate and n-propyl acetate.
9. The method for preparing the clean high-adhesion lithium battery composite diaphragm, which is disclosed in claim 6, is characterized in that: in the fourth step, the curing temperature is 60-80 ℃ and the curing time is 2-3h.
10. The method for preparing the clean high-adhesion lithium battery composite diaphragm, which is disclosed in claim 6, is characterized in that: the specification of the bar coater is 12-20 mu m, and the base film is one or more of PE, PP, PET and a composite film thereof.
CN202310472578.6A 2023-04-27 2023-04-27 Clean high-adhesion-performance lithium battery composite diaphragm and preparation method thereof Pending CN116247382A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118126644A (en) * 2024-05-08 2024-06-04 宁波长阳科技股份有限公司 Main gate-free heterojunction battery packaging adhesive film and preparation method thereof

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