CN111244374A - Coating diaphragm with improved structure and preparation method thereof - Google Patents
Coating diaphragm with improved structure and preparation method thereof Download PDFInfo
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- CN111244374A CN111244374A CN202010251477.2A CN202010251477A CN111244374A CN 111244374 A CN111244374 A CN 111244374A CN 202010251477 A CN202010251477 A CN 202010251477A CN 111244374 A CN111244374 A CN 111244374A
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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
- 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
- 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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The application discloses a coating diaphragm with an improved structure and a preparation method thereof. The coated diaphragm comprises a base film and a polymer coating coated on at least one surface of the base film, wherein the polymer coating is coated on the surface of the base film by coating slurry made of gel polymer particles; the polymer coating is distributed on the base film in a linear shape along the longitudinal direction, the line width is 0.5-1 m, and the line interval is 0.5-5 m. The coating diaphragm solves the problems of battery core bulge and battery deformation through a specially designed coating structure distributed in a stripe shape; the safety performance of the lithium ion battery is improved, and the service life of the battery is prolonged. This application coating diaphragm both can make conventional square, battery such as cylindrical, also can be through adjusting polymer coating line width and interval, folding special-shaped battery such as other rectangular shapes, polygons of formation, extension electric core preparation direction to further improve the security and the battery energy density of battery, extension battery cycle life.
Description
Technical Field
The application relates to the field of battery diaphragms, in particular to a coating diaphragm with an improved structure and a preparation method thereof.
Background
With the increasing energy density of lithium ion power batteries, the safety problem becomes the first problem to be solved in battery design. Particularly, when the energy density of the single battery reaches 300Wh/kg, the traditional polyolefin diaphragm and the ceramic diaphragm are difficult to meet the requirements of battery application. Due to the contribution of the polymer coating diaphragm to the structural design of the battery core, the safety performance of the battery is improved to a great extent, the service life of the battery is prolonged, and the polymer coating diaphragm becomes the first choice for the application of the power battery.
At present, a power battery cell comprises a square battery, a soft package battery and a cylinder, wherein the square battery adopting a winding process is more adopted by a cell manufacturer due to high manufacturing efficiency. However, the energy density of the battery cell is higher and higher, and the expansion and shrinkage rate of the electrode generated in the charging and discharging process is relatively large, and particularly, in the case of a battery cell in a winding process, the battery cell is easy to bulge under a certain winding tension of an electrode plate, and finally, the battery is deformed, so that the battery cell is scrapped. In addition, as the core power of the new energy automobile, the key point for solving the problems of safety, endurance and service life of the new energy automobile is to further improve the safety, cycle life and energy density of the battery.
Disclosure of Invention
It is an object of the present application to provide a structurally improved coated separator and a method of making the same.
In order to achieve the purpose, the following technical scheme is adopted in the application:
one aspect of the present application discloses a structure-improved coated separator, including a base film and a polymer coating layer coated on at least one surface of the base film, the polymer coating layer being formed by coating a coating slurry made of gel polymer particles on the surface of the base film; and the polymer coating is distributed on the base film in a linear shape along the longitudinal direction, the line width is 0.5-1 m, and the line interval is 0.5-5 m.
The gel polymer coating diaphragm has better air permeability through the design of the stripe-shaped coating, and solves the problems of battery core bulge and battery deformation; moreover, the stripe coating has higher ionic conductivity, can obviously improve the liquid absorption and the liquid retention of the porous base membrane, and the gel polymer coating diaphragm has good cohesiveness with the anode and the cathode; the coating diaphragm improves the safety performance of the lithium ion battery and prolongs the service life of the lithium ion battery. In addition, the coating diaphragm with the coating structure distributed in the stripe shape can be used for manufacturing conventional square, cylindrical and other batteries, more importantly, the polymer coating can be folded to form other strip-shaped, polygonal and other special-shaped batteries by adjusting the line width and line interval of the polymer coating, so that the manufacturing direction of the battery core is expanded; by amplifying the manufacturing direction of the battery core, for example, designing a special-shaped battery with a special shape meeting the use requirement or other aspects, the safety and the energy density of the battery can be further improved, and the cycle life of the battery is prolonged.
Preferably, the polymer coating has a thickness of 0.5 μm to 10 μm.
More preferably, the polymer coating has a thickness of 0.5 μm to 4 μm.
Preferably, the line width is 0.5 μm to 100mm and the line spacing is 0.5 μm to 1 m.
In the stripe coating of the present application, the interval between lines is usually 0.5 μm to 1000 mm; however, for some special use requirements, the spacing of the lines may be increased to 5m or even more. As for the line width, it is usually 0.5 μm to 100 mm; however, for some special use requirements, the line width can be increased to 1 m.
Preferably, the gel polymer particles are made of one or a copolymer or a mixture of at least two of polyvinylidene fluoride, polyurethane, polyethylene oxide, polypropylene oxide, polyacrylonitrile, polyacrylamide, polymethyl acrylate, polymethyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone and polytetraethylene glycol diacrylate.
Preferably, the coating slurry includes 10-20 parts by weight of the gel polymer particles, 0-30 parts by weight of the additive, and 60-80 parts by weight of the solvent.
It should be noted that, the additives in the coating slurry of the present application may be selectively added according to the requirements, for example, according to different coating modes, the properties such as the consistency of the coating slurry need to be adjusted, and the thickening agent, the wetting agent, etc. may be selectively added. In one implementation of the present application, since the oily coating slurry is used, i.e., the coating slurry is prepared using an organic solvent, the binder may not be added, and only the gel polymer particles need to be mixed with the organic solvent.
Preferably, the additive is at least one of a surfactant, a wetting agent, a thickener, a dispersant, a binder and a stabilizer.
Preferably, the surfactant is at least one of ethylene oxide polymer and polyether polymer.
Preferably, the wetting agent is at least one of fluoroalkyl methoxy ether alcohol, fluoroalkyl ethoxy ether alcohol, alkylphenol ethoxylate, fatty alcohol ethoxylate, fatty acid ethoxylate and polyoxyethylene.
Preferably, the thickener is at least one of sodium carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl methyl cellulose.
Preferably, the dispersant is at least one of sodium polyacrylate, ammonium polyacrylate, n-butanol, cyclohexanol and ethanol.
Preferably, the binder is a polyacrylic binder, or at least one of styrene-butadiene latex, styrene-acrylic latex, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and polyurethane.
Preferably, the stabilizer is generally an amine compound, such as ammonia, ethanol, or the like.
Preferably, the solvent is at least one of acetone, N-methylpyrrolidone, dimethylacetamide, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, dimethyl carbonate, propylene carbonate, ethylene carbonate, absolute ethanol, deionized water, cyclohexanone, ethyl acetate, and N-propanol.
Preferably, the base membrane is one or a composite membrane formed by laminating at least two of a polyolefin membrane, a ceramic coating membrane, a non-woven fabric membrane and a polyimide membrane; the ceramic coating diaphragm is formed by coating a polyolefin diaphragm with a ceramic coating.
Preferably, the polyolefin separator is a microporous membrane made of at least one of polyethylene, polypropylene, poly-1-butene and polypentene.
Another aspect of the present application discloses a method for preparing the coated separator of the present application, comprising the steps of,
(1) mixing the gel polymer particles, the solvent and the additive, and uniformly stirring to obtain coating slurry;
(2) and (3) coating the coating slurry prepared in the step (1) on the surface of the base film by adopting at least one of roll coating, dip coating, blade coating, spray coating, brush coating and extrusion coating, and drying to obtain the coating diaphragm.
Preferably, in step (1), the particle size of the gel polymer particles is 0.01 μm. ltoreq. D50. ltoreq.5 μm.
More preferably, the gel polymer particles have a particle size of 0.1 μm. ltoreq. D50. ltoreq.3 μm.
More preferably, the gel polymer particles have a particle size of 0.1 μm. ltoreq. D50. ltoreq.1 μm.
Due to the adoption of the technical scheme, the beneficial effects of the application are as follows:
the coating diaphragm solves the problems of battery core bulge and battery deformation through the specially designed coating structure distributed in a stripe shape; thereby improving the safety performance of the lithium ion battery and prolonging the service life of the lithium ion battery. The utility model provides a coating diaphragm of stripe distribution's coating structure both can make conventional square, battery such as cylindrical, also can be through adjustment polymer coating line width and lines interval, folding special-shaped battery such as other rectangular shapes, polygons of formation, extension electric core preparation direction to further improve battery security and battery energy density, extension battery cycle life.
Drawings
FIG. 1 is a schematic representation of the structure of a polymer-coated membrane of a striped coating in an embodiment of the present application.
Detailed Description
At present, no good solution is provided for the problems of battery deformation, battery core scrapping and the like caused by expansion and contraction of the battery in the charging and discharging process and battery core bulging. In addition, how to further improve the safety, cycle life and energy density of the battery is a key point for solving the safety, endurance and service life of the new energy automobile.
The structure of the coated separator is improved in an inventive way, namely, a striped coating which is distributed along the longitudinal direction (MD) and has the line width of 0.5-1 m and the line interval of 0.5-5 m is formed on the base film in a line shape, namely, as shown in figure 1, a striped coating 02 is formed on the surface of the base film 01 along the MD direction. The coating diaphragm of the application enables the polymer coating diaphragm to have better air permeability, and solves the problems of expansion and contraction, battery core bulge and battery deformation; moreover, the stripe coating has higher ionic conductivity and can obviously improve the liquid absorption and liquid retention of the porous base membrane; in addition, the coating diaphragm that stripe form distributes of this application not only can make conventional square, cylindrical battery etc. but also can fold through adjustment line width and line interval and form other special-shaped batteries such as rectangular shape, polygon, expand electric core preparation direction to further improve battery security and battery energy density, prolonged battery cycle life.
The coating diaphragm can improve the safety and service life of the battery, and on one hand, the coating diaphragm solves the problems of expansion and contraction, battery core bulge, battery deformation and the like; on the other hand, when the coating diaphragm is particularly used for a special-shaped battery, the manufacturing direction of a battery core can be enlarged, and the safety, the energy density and the service life of the battery are further improved from another angle.
The present application is described in further detail below with reference to specific embodiments and the attached drawings. The following examples are intended to be illustrative of the present application only and should not be construed as limiting the present application.
Example 1
In the embodiment, a polyethylene microporous membrane with the diameter of 8 μm, which is purchased from Shenzhen Zhongxing New Material technology GmbH, is used as a base membrane, and a coating with stripes is coated on the surface of the base membrane along the longitudinal direction by gel polymer coating slurry of polyvinylidene fluoride-hexafluoropropylene, wherein the preparation method comprises the following steps:
(1) pulping
10.0kg of polyvinylidene fluoride-hexafluoropropylene powder having an average particle size of 200nm was added to 85kg of acetone solution, stirred and heated to 50 ℃ to dissolve for 6 hours, and then 5kg of a mixed solution of dimethyl carbonate and ethanol at a ratio of 1:1 was added, stirred for 0.5 hour, and cooled to room temperature to obtain a polyvinylidene fluoride-hexafluoropropylene acetone solution, i.e., a polyvinylidene fluoride-hexafluoropropylene gel polymer coating slurry of this example.
(2) Coating of
Coating the prepared gel polymer coating slurry on the base film of the embodiment, coating on two sides, drying at 50 ℃, and obtaining a gel polymer coating diaphragm with the thickness of 10.2 mu m, wherein the dry thickness of the coating on each side is 1.1 mu m; the coating was controlled to form stripe-like coatings with a line width of 1 μm and a line interval of 10 μm on both sides.
Example 2
In this example, a 12 μm ceramic diaphragm from Shenzhen Zhongxing New Material technology GmbH was used as a base film, and a striped coating was applied to the surface of the base film in the longitudinal direction using a polyvinylidene fluoride-hexafluoropropylene gel polymer coating slurry. Wherein, the 12 μm ceramic diaphragm is a polyethylene microporous membrane with the diameter of 8 μm and a ceramic coating with the diameter of 4 μm coated on one surface. The polymer-coated separator of this example was prepared specifically as follows:
(1) pulping
10.0kg of polyvinylidene fluoride-hexafluoropropylene powder having an average particle size of 200nm was added to 85kg of acetone solution, stirred and heated to 50 ℃ to dissolve for 6 hours, and then 5kg of a mixed solution of dimethyl carbonate and ethanol at a ratio of 1:1 was added, stirred for 0.5 hour, and cooled to room temperature to obtain a polyvinylidene fluoride-hexafluoropropylene acetone solution, i.e., a polyvinylidene fluoride-hexafluoropropylene gel polymer coating slurry of this example.
(2) Coating of
Coating the prepared gel polymer coating slurry on a ceramic diaphragm base film with the thickness of 12 microns, coating on two sides, drying at 50 ℃, and obtaining a gel polymer coating diaphragm with the thickness of 14 microns, wherein the coating on each side is dry and thick by 1 micron; the coating was controlled to form stripe-like coatings with a line width of 1 μm and a line interval of 10 μm on both sides.
Example 3
In the embodiment, a polyethylene microporous membrane with the diameter of 8 μm, which is purchased from Shenzhen Zhongxing New Material technology GmbH, is used as a base membrane, and a coating with stripes is coated on the surface of the base membrane along the longitudinal direction by gel polymer coating slurry of polyvinylidene fluoride-hexafluoropropylene, wherein the preparation method comprises the following steps:
(1) pulping
15.0kg of polyvinylidene fluoride-hexafluoropropylene powder having an average particle size of 200nm was added to 85kg of deionized water, a dispersant was added thereto, and the mixture was stirred for 1.5 hours, followed by addition of a wetting agent, a binder and a surfactant, and further stirring was continued for 1.5 hours, to obtain an aqueous solution of polyvinylidene fluoride-hexafluoropropylene, i.e., a gel polymer coating slurry of polyvinylidene fluoride-hexafluoropropylene of this example.
(2) Coating of
Coating the prepared gel polymer coating slurry on a polyethylene base film with the thickness of 8 mu m, coating on a single surface, drying at 50 ℃, and obtaining a gel polymer coating diaphragm with the thickness of 9.9 mu m, wherein the dry thickness of the coating on each surface is 1.9 mu m; the coating was controlled to form stripe-like coatings with a line width of 1 μm and a line interval of 10 μm on both sides. And drying to finally obtain the polymer diaphragm.
Comparative experiment 1
Comparative analysis was performed using the polyethylene microporous membrane of 8 μm of example 1 as comparative test 1.
Comparative experiment 2
Comparative analysis was performed using the 12 μm ceramic separator of example 2 as comparative test 2.
Comparative experiment 3
Comparative experiment 3 was conducted using a commercially available polymer-coated membrane having a thickness of 10 μm, wherein the 10 μm polymer-coated membrane was coated with a 1 μm thick polyvinylidene fluoride-hexafluoropropylene coating layer normally over both sides with a 8 μm polyethylene microporous membrane as a base membrane. The test is different from example 1 in the way of covering the coating, and example 1 uses a striped coating, while the test is a normal film covering, i.e. the coating is a film covering both surfaces of the base film in a normal way.
Comparative experiment 4
A polymer coating diaphragm with the thickness of 14 mu m, model ZP14 of Shenzhen Zhongxing New Material technology corporation, Inc., is adopted as a comparison test 4 for comparison analysis, wherein the polymer coating diaphragm with the thickness of 14 mu m takes a polyethylene microporous membrane with the thickness of 8 mu m as a base membrane, a ceramic coating with the thickness of 4 mu m is normally coated on one side of the polymer coating diaphragm, and then a polyvinylidene fluoride-hexafluoropropylene coating with the thickness of 1 mu m is normally coated on the two sides of the polymer coating diaphragm. The test is different from example 2 in the way of covering the coating, example 2 uses a striped coating, while the test is a normal film covering, i.e. the coating is a film covering both surfaces of the base film in a normal way.
The polymer-coated separators or base films of the above examples 1 to 3 and comparative experiments 1 to 4 were subjected to thickness (μm), gas permeability (s/100mL), ion conductivity (μ s/cm), liquid absorption rate (%), liquid retention rate (%), positive electrode dry adhesive strength (N/m), negative electrode dry adhesive strength (N/m), and positive electrode wet adhesive strength (N/m) tests. The specific test method is as follows:
the thickness testing method is carried out by referring to GB/T6672-2001, a Mark thickness gauge with a flat contact head is adopted for measurement, the gauge is calibrated and cleared before measurement, the contact surface is kept clean, one point is taken along the TD direction of the film every 5cm for measurement, and the average value of 5 points is measured to be the thickness of the film.
And (3) testing the air permeability value: and taking 5 samples and testing by using a ventilation instrument by referring to GB/T458-2008, and taking the measured average value as the ventilation value of the sample to be measured.
Dry adhesive strength (N/m) test of positive and negative electrodes: cutting a sample with the width of 20mm multiplied by the length of 80mm from the diaphragm and the pole piece, pressing the sample on a hot press, fixing one end of the diaphragm and one end of the pole piece on a universal tensile machine, peeling the sample at 180 degrees at a constant speed of 10mm/min, and repeating the experiment for 5 times to obtain an average value.
The wet adhesion strength (N/m), namely the adhesive force after winding the anode, the cathode and the diaphragm and soaking the electrolyte, is tested by the following specific test method: cutting a sample with the width of 63.5mm from the diaphragm, manually winding the sample into a battery, standing for 0.5h after liquid injection, disassembling the battery after hot pressing by a hot press, a, observing the adhesion tightness of the diaphragm and the pole piece, and observing the amount of the active substances adhered to the negative pole piece; b. a sample of 20mm multiplied by 80mm is cut out, one end of the diaphragm and one end of the pole piece are fixed on a universal tensile machine, peeling is carried out at 180 degrees at a constant speed of 10mm/min, the experiment is repeated for 5 times, and the average value is obtained, so that the wet adhesion strength (N/m) of the pole piece is obtained.
And (3) ion conductivity test: the inert stainless steel electrode is adopted to manufacture a symmetrical battery for testing, the resistance of the battery is correspondingly increased along with the increase of the number of layers of the diaphragm, the battery resistance is in a linear relation, and the corresponding slope is the diaphragm resistance. The diaphragm ionic conductivity calculation formula is as follows: σ S ═ d/(RS × a × 10);
wherein, sigma S is the ionic conductivity of the diaphragm, and the unit is mS/cm; d is the thickness of the diaphragm, measured by a thickness gauge in μm; RS is the diaphragm resistance with unit omega; a is the effective area of the diaphragm in the symmetrical battery, and the value is 6cm2(ii) a In the denominator, "10" is a dimension conversion ratio.
Testing the liquid absorption rate and the liquid retention rate of the diaphragm, weighing a coating film with the size of 10 multiplied by 10cm, wherein the coating film has the mass of W0, soaking the coating film into a mixed solution of Ethylene Carbonate (EC)/Propylene Carbonate (PC) in a ratio of 1:1 at room temperature, standing for 2h, then completely absorbing the electrolyte on the surface by using filter paper, weighing, recording the mass as W1, standing for 10min at room temperature, weighing again, recording the mass as W2
Liquid absorption rate (W2-W0)/W0
Liquid retention rate (W1-W2)/(W1-W0)
The results of the tests are shown in Table 1.
Table 1 separator performance test results
In Table 1, the thickness is in μm, "dry adhesion" means dry adhesive strength in N/m, "wet adhesion" means wet adhesive strength in N/m, air permeability in s/100mL, ionic conductivity in μ s/cm, and liquid absorption and retention in%.
The results show that the polymer diaphragms in the examples 1, 2 and 3 have good air permeability and high ionic conductivity, the liquid absorption and liquid retention of the porous base membrane can be obviously improved, and the adhesion force between the polymer diaphragms and the positive and negative electrodes is high. In particular, in the aspect of the air permeability value, the example 1 is obviously superior to the comparative test 3 of the same type, and the example 2 is obviously superior to the comparative test 4 of the same type; the polymer separators of examples 1 and 2 also outperformed the same type of commercial product in terms of ionic conductivity. Therefore, the polymer coating diaphragm of embodiments 1 and 2 has better gas permeability, can solve the problem that electric core bulges, battery warp, improves lithium ion battery's security performance, prolongs lithium ion battery's life, and in addition, the coating structure that the stripe distributes both can make conventional square, cylindrical etc. battery, also can be through adjusting lines width and lines interval, folding formation other special-shaped batteries such as rectangular shape, polygon, extension electric core preparation direction.
Example 4
In this example, based on the above tests and comparison, stripe design of the coating layer was further tested, that is, stripe coating layers with different line widths and different line intervals were formed by the same coating method as in example 1 based on the base film and the coating slurry in example 1, and the coating thickness was the same as in example 1, and the specific tests were as follows:
test 1: the width of the lines is 0.5 μm, and the interval between the lines is 0.5 μm;
test 2: the width of the lines is 2 μm, and the line interval is 2 μm;
test 3: the width of the lines is 4 μm, and the line interval is 4 μm;
test 4: the width of the lines is 6 μm, and the line interval is 8 μm;
test 5: the width of the lines is 8 μm, and the line interval is 10 μm;
test 6: the line width is 10 μm, and the line interval is 10 μm;
test 7: the line width is 12 μm, and the line interval is 10 μm;
test 8: the line width is 14 μm, and the line interval is 12 μm;
test 9: the width of the lines is 1mm, and the line interval is 900 mm;
test 10: the width of the lines is 10mm, and the line interval is 1000 mm;
test 11: the width of the lines is 100mm, and the interval between the lines is 1000 mm;
test 12: the width of the lines is 500mm, and the line interval is 2000 mm;
test 13: the width of the lines is 1000mm, and the line spacing is 5000 mm.
In this example, 13 coated membranes of different line widths and spacings were prepared according to the above 13 tests and tested for peel strength and air permeability, respectively. The results show that the 13 polymer-coated membranes of this example all have better peel strength, comparable to example 1; the breathability is inversely related to the area covered by the coating, i.e. the wider the lines of the coating, the smaller the spacing, the poorer the breathability. Therefore, analysis has shown that a preferred embodiment is a coating with line widths of 0.5 μm to 100mm and line spacings of 0.5 μm to 1000 mm. Line widths too small, e.g., less than 0.5 μm, can affect the performance of the coating; the lines are too wide, if the lines are larger than 100mm, the improvement of air permeability is not facilitated, and the problems of battery core bulge and battery deformation are not facilitated to be solved. As for the line interval, similarly, the interval is too small, which is not favorable for improving the air permeability; too large a spacing will affect the properties of the coating itself.
However, in the actual production process, the line spacing can be very large according to special use requirements, for example, the applicant designs a stripe-shaped coating diaphragm with the line spacing of 1.2m and also designs a stripe-shaped coating diaphragm with the spacing of 5m when carrying out the test, but the performance of the corresponding coating can be influenced.
The foregoing is a more detailed description of the present application in connection with specific embodiments thereof, and it is not intended that the present application be limited to the specific embodiments thereof. It will be apparent to those skilled in the art from this disclosure that many more simple derivations or substitutions can be made without departing from the spirit of the disclosure.
Claims (10)
1. A structurally improved coated separator comprising a base film and a polymer coating applied to at least one surface of the base film, wherein: the polymer coating is formed by coating slurry made of gel polymer particles on the surface of a base film; and the polymer coating is distributed on the base film in a linear shape along the longitudinal direction, the line width is 0.5-1 m, and the line interval is 0.5-5 m.
2. The coated membrane of claim 1, wherein: the thickness of the polymer coating is 0.5-10 μm;
preferably, the thickness of the polymer coating is 0.5 μm to 4 μm;
preferably, the line width is 0.5 μm to 100mm, and the line interval is 0.5 μm to 1 m.
3. The coated membrane of claim 1, wherein: the gel polymer particles are made of one or a copolymer or a mixture of at least two of polyvinylidene fluoride, polyurethane, polyethylene oxide, polypropylene oxide, polyacrylonitrile, polyacrylamide, polymethyl acrylate, polymethyl methacrylate, polyvinyl acetate, polyvinyl pyrrolidone and polytetraethylene glycol diacrylate.
4. A coated membrane according to any one of claims 1 to 3, wherein: the coating slurry comprises 10-20 parts by weight of gel polymer particles, 0-30 parts by weight of additives and 60-80 parts by weight of solvent.
5. The coated membrane of claim 4, wherein: the additive is at least one of a surfactant, a wetting agent, a thickening agent, a dispersing agent, a binder and a stabilizer.
6. The coated membrane of claim 5, wherein: the surfactant is at least one of ethylene oxide polymer and polyether polymer;
preferably, the wetting agent is at least one of fluoroalkyl methoxy ether alcohol, fluoroalkyl ethoxy ether alcohol, alkylphenol ethoxylate, fatty alcohol ethoxylate, fatty acid ethoxylate and polyoxyethylene;
preferably, the thickener is at least one of sodium carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl methyl cellulose;
preferably, the dispersant is at least one of sodium polyacrylate, ammonium polyacrylate, n-butanol, cyclohexanol and ethanol;
preferably, the binder is a polyacrylic binder, or at least one of styrene-butadiene latex, styrene-acrylic latex, polyvinyl alcohol, ethylene-vinyl acetate copolymer and polyurethane;
preferably, the stabilizer is an amine compound.
7. The coated membrane of claim 4, wherein: the solvent is at least one of acetone, N-methyl pyrrolidone, dimethylacetamide, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, dimethyl carbonate, propylene carbonate, ethylene carbonate, absolute ethyl alcohol, deionized water, cyclohexanone, ethyl acetate and N-propanol.
8. The coated membrane of claim 1, wherein: the base membrane is one or a composite membrane formed by laminating at least two of a polyolefin membrane, a ceramic coating membrane, a non-woven fabric membrane and a polyimide membrane; the ceramic coating diaphragm is formed by coating a polyolefin diaphragm with a ceramic coating;
preferably, the polyolefin separator is a microporous membrane prepared from at least one of polyethylene, polypropylene, poly-1-butene and polypentene.
9. The method for producing a coated separator according to any one of claims 1 to 8, wherein: comprises the following steps of (a) carrying out,
(1) mixing the gel polymer particles, the solvent and the additive, and uniformly stirring to obtain the coating slurry;
(2) and (2) coating the coating slurry prepared in the step (1) on the surface of a base film by adopting at least one of roll coating, dip coating, blade coating, spray coating, brush coating and extrusion coating, and drying to obtain the coating diaphragm.
10. The method of claim 9, wherein: in the step (1), the particle size of the gel polymer particles is not less than 0.01 mu m and not more than D50 and not more than 5 mu m; preferably 0.1 mu m < D50 < 3 mu m; more preferably 0.1. mu.m.ltoreq.D 50.ltoreq.1. mu.m.
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| CN111769243A (en) * | 2020-06-29 | 2020-10-13 | 珠海恩捷新材料科技有限公司 | Digital battery diaphragm and preparation method thereof |
| CN112194936A (en) * | 2020-09-18 | 2021-01-08 | 河北金力新能源科技股份有限公司 | Ultra-high dispersion type PVDF slurry, diaphragm and preparation method thereof |
| CN113224467A (en) * | 2021-05-27 | 2021-08-06 | 江苏星源新材料科技有限公司 | Coating diaphragm |
| CN115332723A (en) * | 2021-05-10 | 2022-11-11 | 江苏星源新材料科技有限公司 | Composite diaphragm and preparation method thereof |
| CN115411459A (en) * | 2022-09-27 | 2022-11-29 | 惠州锂威新能源科技有限公司 | Diaphragm, battery and preparation method of diaphragm |
| CN115411457A (en) * | 2020-06-08 | 2022-11-29 | 德州东鸿制膜科技有限公司 | Lithium ion battery diaphragm and preparation method and application thereof |
| CN115498360A (en) * | 2022-11-15 | 2022-12-20 | 宁德卓高新材料科技有限公司 | Twill polymer composite diaphragm and preparation method and application thereof |
| WO2023273652A1 (en) * | 2021-07-02 | 2023-01-05 | 宁德时代新能源科技股份有限公司 | Diaphragm, lithium-ion battery, battery module, battery pack and power device |
| WO2023093789A1 (en) * | 2021-07-23 | 2023-06-01 | 江苏天合储能有限公司 | Lithium ion battery separator |
| WO2024016952A1 (en) * | 2023-05-09 | 2024-01-25 | 湖北亿纬动力有限公司 | Composite separator and preparation method therefor, and secondary battery |
| CN117477168A (en) * | 2023-12-26 | 2024-01-30 | 新乡华锐锂电新能源股份有限公司 | Isolation film for sodium ion battery and preparation method thereof |
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Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115411457A (en) * | 2020-06-08 | 2022-11-29 | 德州东鸿制膜科技有限公司 | Lithium ion battery diaphragm and preparation method and application thereof |
| CN111769243A (en) * | 2020-06-29 | 2020-10-13 | 珠海恩捷新材料科技有限公司 | Digital battery diaphragm and preparation method thereof |
| CN111769243B (en) * | 2020-06-29 | 2021-03-19 | 珠海恩捷新材料科技有限公司 | Digital battery diaphragm and preparation method thereof |
| WO2022001174A1 (en) * | 2020-06-29 | 2022-01-06 | 珠海恩捷新材料科技有限公司 | Digital battery separator and preparation method therefor |
| CN112194936A (en) * | 2020-09-18 | 2021-01-08 | 河北金力新能源科技股份有限公司 | Ultra-high dispersion type PVDF slurry, diaphragm and preparation method thereof |
| CN115332723A (en) * | 2021-05-10 | 2022-11-11 | 江苏星源新材料科技有限公司 | Composite diaphragm and preparation method thereof |
| CN115332723B (en) * | 2021-05-10 | 2024-04-02 | 江苏星源新材料科技有限公司 | Composite diaphragm and preparation method thereof |
| CN113224467A (en) * | 2021-05-27 | 2021-08-06 | 江苏星源新材料科技有限公司 | Coating diaphragm |
| WO2023273652A1 (en) * | 2021-07-02 | 2023-01-05 | 宁德时代新能源科技股份有限公司 | Diaphragm, lithium-ion battery, battery module, battery pack and power device |
| WO2023093789A1 (en) * | 2021-07-23 | 2023-06-01 | 江苏天合储能有限公司 | Lithium ion battery separator |
| CN115411459A (en) * | 2022-09-27 | 2022-11-29 | 惠州锂威新能源科技有限公司 | Diaphragm, battery and preparation method of diaphragm |
| CN115498360A (en) * | 2022-11-15 | 2022-12-20 | 宁德卓高新材料科技有限公司 | Twill polymer composite diaphragm and preparation method and application thereof |
| WO2024016952A1 (en) * | 2023-05-09 | 2024-01-25 | 湖北亿纬动力有限公司 | Composite separator and preparation method therefor, and secondary battery |
| CN117477168A (en) * | 2023-12-26 | 2024-01-30 | 新乡华锐锂电新能源股份有限公司 | Isolation film for sodium ion battery and preparation method thereof |
| CN117477168B (en) * | 2023-12-26 | 2024-03-08 | 新乡华锐锂电新能源股份有限公司 | Isolation film for sodium ion battery and preparation method thereof |
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