CN110148695B - Preparation method of battery diaphragm - Google Patents
Preparation method of battery diaphragm Download PDFInfo
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- CN110148695B CN110148695B CN201910341649.2A CN201910341649A CN110148695B CN 110148695 B CN110148695 B CN 110148695B CN 201910341649 A CN201910341649 A CN 201910341649A CN 110148695 B CN110148695 B CN 110148695B
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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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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/431—Inorganic material
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
The invention provides a preparation method of a battery diaphragm, which comprises the following steps: s1: coating a ceramic coating liquid containing a hydrophobic substance on a base film under a light-shielding condition to obtain a ceramic diaphragm; s2: covering a mask with a pattern on the ceramic diaphragm obtained in the step S1, and performing ultraviolet irradiation to obtain the ceramic diaphragm with a hydrophilic part and a hydrophobic part; s3: the ceramic separator obtained in S2 was coated with the polyvinylidene fluoride dispersion. By adding the hydrophobic substance into the ceramic formula, the problems of hole blocking and needle blocking in spraying are solved; PVDF dot matrix coating can be realized only by a traditional coating mode, high-price equipment is avoided, and cost is saved. And the product performance is equivalent to or better than that of the existing lattice PVDF diaphragm, thereby meeting the market demand. The method is simple and feasible, and can be used for producing the dot matrix PVDF coating diaphragm in a large scale.
Description
Technical Field
The invention relates to the field of battery diaphragm preparation methods, in particular to a battery diaphragm preparation method.
Background
The battery diaphragm is a layer of diaphragm material between the positive electrode and the negative electrode of the battery, is a very critical part in the battery, has direct influence on the safety and the cost of the battery, and has the main functions of: the positive electrode and the negative electrode are separated, electrons in the battery cannot freely pass through the battery, and ions in the electrolyte freely pass between the positive electrode and the negative electrode.
The surface modification of the diaphragm is an important mode for improving the performance of the battery diaphragm, and the common method is a surface coating method. The surface coating method is mainly used for modifying the diaphragm and improving the performance of the battery diaphragm by coating or depositing a layer of thin functional film on the surface. The composition, thickness and form of the coating layer have great influence on the electrochemical properties of the modified diaphragm, so that the performance of the battery is influenced.
The PVDF (polyvinylidene fluoride) -coated lithium ion battery diaphragm is prepared by coating a PVDF material on the surface of a traditional diaphragm through special process treatment. The PVDF coating layer can be combined with an electrolyte in the lithium ion battery to form a stable gel conductive polymer, so that the performance of the lithium ion battery is remarkably improved. However, continuous coating of PVDF affects the air permeability of the separator, and to solve this problem, discontinuous coating, such as dot coating, occurs.
Chinese patent CN106784535A discloses a method for preparing an environment-friendly breathable lithium battery inner diaphragm, wherein PVDF slurry is partially coated on one side or two sides of a base film to form a PVDF dot coating, the PVDF dot coating enables the diaphragm and an electrode to have good adhesive force, and the exposed area without the PVDF slurry can realize effective transmission of lithium ions, so that the multiplying power discharge and cycle life performance of the lithium battery are improved while the air permeability of the original diaphragm is maintained unchanged. However, the screen printing technique adopted in this patent cannot realize industrialization of coating; spray techniques also suffer from the problem of clogging holes or needles.
Chinese patent CN107611315A discloses a punctiform PDVF coating method of a battery diaphragm, but the method mainly adopts an atomizer for spraying, the nozzle of the atomizer is very small, the PVDF macromolecule is easy to block when being sprayed, and the problem of hole blocking cannot be solved by actual continuous production operation, so the implementation is difficult.
In addition, the dot-shaped PDVF coating method can also use spin coating equipment, but the spin coating equipment is expensive, complex to operate and high in cost.
Therefore, it is desirable to provide a simple, effective, inexpensive and feasible method of dot-matrix PDVF coating.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a preparation method of a battery diaphragm.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a preparation method of a battery separator comprises the following steps:
s1: coating a ceramic coating liquid containing a hydrophobic substance on a base film under a light-shielding condition to obtain a ceramic diaphragm;
s2: covering a mask with a pattern on the ceramic diaphragm obtained in the step S1, and performing ultraviolet irradiation to obtain the ceramic diaphragm with a hydrophilic part and a hydrophobic part;
s3: the ceramic separator obtained in S2 was coated with the polyvinylidene fluoride dispersion.
In some embodiments, the ceramic coating solution including a hydrophobic substance in S1 includes: based on 100wt% of solvent, 20-30wt% of alumina ceramic, 0.2-0.8wt% of dispersant, 0.5-2wt% of binder, 0.2-1wt% of thickener or 1-5wt% of hydrophobic substance.
1-5wt% of hydrophobic substance, and too little addition of the hydrophobic substance requires too long ultraviolet exposure time, which is not favorable for continuous production; too much addition affects the coating of the ceramic slurry.
Further, in the ceramic coating liquid, the solvent is deionized water; the dispersing agent is polyethylene glycol and octadecyl trimethyl ammonium chloride; the binder is polyvinylpyrrolidone; the thickening agent is sodium carboxymethyl cellulose; the hydrophobic substance is fluorosilane or alkyl ketene dimer.
Still further, the fluorosilane is tridecafluorooctyltriethoxysilane, heptadecafluorodecyltriethoxysilane or octadecylfluorodecyltriethoxysilane.
Specifically, the preparation method of the ceramic coating liquid comprises the following steps: (1) adding alumina ceramic and a dispersant into a solvent, and stirring; (2) adding a thickening agent and a binder, and stirring; (3) adding hydrophobic substance, stirring to obtain ceramic coating liquid containing hydrophobic substance, and coating with aluminum foil paper in dark place.
Specifically, when the ceramic coating solution containing the hydrophobic substance is coated on the base film, the whole coating process and the drying process after the coating are also required to be carried out under the condition of keeping out of the sun; the thickness of the obtained ceramic diaphragm is 6-20 μm.
The reason for keeping out of the light is that the added hydrophobic substance is sensitive to light, and can react under long-term exposure to light, all become hydrophilic surfaces, and the final dot matrix PVDF distribution cannot be obtained, but the full coverage type PVDF coating is adopted.
Specifically, the base film is a polyolefin base film, preferably a Polyethylene (PE) base film, a polypropylene (PP) base film or a composite film of PE and PP.
In some embodiments, the pattern on the mask may be circular, oval, square, rectangular, triangular, diamond-shaped, or other irregular shapes, among others.
In some of the embodiments, the mask comprises a substrate and a light-tight layer, wherein the substrate is quartz glass, the light-tight layer is a chromium layer plated on the surface of the substrate by a sputtering method, and the chromium layer is about 0.1 μm thick; the pattern shape on the mask is obtained by wet etching.
In some of the embodiments, the pattern on the mask in S2 is circular, with a diameter of 200 μm-1mm and a spacing of 200 μm-1mm, and the diameter of the circle directly affects the size of the subsequent dot matrix PVDF. The coverage rate of PVDF on the diaphragm is 20-50%, if the coverage rate is too high, the adhesive force is improved, but the air permeability is poor; the coverage was too low, the breathability was good, but the adhesion was too low.
As shown in FIG. 1, the white part is a light-transmitting part, the diameter of the circle is generally 200 μm-1mm, the black part is a non-light-transmitting part, and the distance is 200 μm-1 mm.
In some examples, the ceramic diaphragm obtained in S1 is covered with a patterned mask and irradiated with ultraviolet light at an irradiation intensity of 250-500mj/cm2The irradiation time is 2s-100 s.
The UV light exposure time is related to the UV light intensity, and the higher the UV light intensity, the less exposure time is required, and the intensity can be adjusted by the UV light knob.
Ultraviolet light penetrates through the circular holes of the mask, the part irradiated on the ceramic diaphragm is chemically reacted to become hydrophilic, the contact angle is 50-65 degrees, the part not irradiated is still hydrophobic, the contact angle is 135-145 degrees, and therefore a hydrophilic-hydrophobic micro-pattern is constructed.
In some of these embodiments, the polyvinylidene fluoride dispersion of S3 comprises: calculated by taking the solvent as 100wt%, 20-40wt% of polyvinylidene fluoride, 1-5wt% of dispersing agent, 1-5wt% of binder or 0.2-1.0wt% of wetting agent.
Further, in the polyvinylidene fluoride dispersion liquid, the solvent is deionized water; the polyvinylidene fluoride is polyvinylidene fluoride homopolymer or polyvinylidene fluoride copolymer; the dispersant and the binder are water-soluble polymers.
Further, in the polyvinylidene fluoride dispersion liquid, the dispersing agent is sodium dodecyl benzene sulfate, polyacrylate or copolymer containing pigment affinity group structure; the binder is styrene butadiene rubber, polyvinylpyrrolidone, acrylates or polyvinyl alcohol; the wetting agent is a polyether silicone copolymer.
Further, in the polyvinylidene fluoride dispersion, the dispersant is sodium dodecyl benzene sulfate, polyacrylate or
-LP 22136; the binder is styrene butadiene rubber, polyvinylpyrrolidone, acrylates or polyvinyl alcohol; the wetting agent is a polyether silicone copolymer.
In some embodiments, the polyvinylidene fluoride dispersion of S2 is prepared by: (1) adding a dispersing agent and a wetting agent into deionized water, and stirring for dissolving; (2) adding polyvinylidene fluoride into the mixture, continuously stirring the mixture, and oscillating the mixture by using a high-speed oscillator to prepare polyvinylidene fluoride pre-dispersion liquid; (3) and adding the binder into the polyvinylidene fluoride pre-dispersion liquid, and stirring.
In some embodiments, polyvinylidene fluoride dispersion is coated on the ceramic membrane obtained in step S2 and dried to obtain a dot matrix PDVF coated membrane, wherein the PVDF coating layer has a thickness of 1-10 μm. When the polyvinylidene fluoride dispersion liquid is coated on the ceramic diaphragm obtained in the step S2, PVDF is subjected to self-assembly action and deposited on a hydrophilic part of the ceramic diaphragm and is not deposited on a hydrophobic part, so that the dot matrix coating of the PVDF is realized.
The coating method of the polyvinylidene fluoride dispersion is not particularly limited, and examples thereof include: knife coating, slot extrusion coating, or dimpled coating.
The invention has the beneficial effects that: (1) the hydrophobic substance is added into the ceramic formula, so that the problems of hole blocking and needle blocking in spraying are solved; PVDF is uniformly distributed, and the spraying stability is good. The method is simple and feasible, has operability, and can be used for continuously producing the dot matrix PVDF coating diaphragm on a large scale. (2) The battery diaphragm obtained by the invention has good air permeability. (3) The battery diaphragm obtained by the invention has good binding power. (4) The battery diaphragm obtained by the invention has good capacity retention rate in the battery test.
Definition of terms
All ranges cited herein are inclusive, unless expressly stated to the contrary.
The terms "a" or "an" are used herein to describe elements and components described herein. This is done merely for convenience and to provide a general sense of the scope of the invention. Such description should be understood to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise. "plural" means two or more.
The numbers in this disclosure are approximate, regardless of whether the word "about" or "approximately" is used. The numerical value of the number may have differences of 1%, 2%, 5%, 7%, 8%, 10%, etc. Whenever a number with a value of N is disclosed, any number with a value of N +/-1%, N +/-2%, N +/-3%, N +/-5%, N +/-7%, N +/-8% or N +/-10% is explicitly disclosed, wherein "+/-" means plus or minus, and a range between N-10% and N + 10% is also disclosed.
The following definitions, as used herein, should be applied unless otherwise indicated. For the purposes of the present invention, the chemical elements are in accordance with the CAS version of the periodic Table of elements, and the 75 th version of the handbook of chemistry and Physics, 1994. In addition, general principles of Organic Chemistry can be referred to as described in "Organic Chemistry", Thomas Sorrell, University Science Books, Sausaltito: 1999, and "March's Advanced Organic Chemistry" by Michael B.Smith and Jerry March, John Wiley & Sons, New York:2007, the entire contents of which are incorporated herein by reference.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can also be used in the practice or testing of embodiments of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety, unless a specific section is cited. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.
Drawings
FIG. 1 is a mask with circular holes according to the present invention.
FIG. 2 shows a dot matrix polyvinylidene fluoride coated membrane obtained by the present invention.
Wherein 1 represents a portion of the mask through which ultraviolet light is transmitted and 2 represents a portion of the mask through which light is not transmitted.
3 represents the PVDF lattice and 4 represents the ceramic part not coated with PVDF.
Detailed Description
Example 1
1. Coating of ceramic coating liquid
Adding 25g of alumina ceramic into 100g of deionized water, adding 0.2g of dispersant polyethylene glycol and octadecyl trimethyl ammonium chloride respectively, and stirring at a high speed of 3000r/min for 4 hours; secondly, 0.6g of sodium carboxymethylcellulose and 0.5g of polyvinylpyrrolidone are added successively and stirred until the sodium carboxymethylcellulose and the polyvinylpyrrolidone are dissolved, wherein the stirring speed is 1000 r/min; continuing to add 1g of tridecafluorooctyltriethoxysilane, uniformly stirring and dispersing for 4 hours at the stirring speed of 1000r/min to obtain a ceramic coating liquid; fourthly, coating the ceramic coating liquid on the base film by using a flat plate coating machine, drying for later use, and performing the third step and the fourth step under a light-proof condition; the thickness of the obtained ceramic separator was 16 μm.
2. Ultraviolet light irradiation
The MASK plate (PHOTO-etching chromium plate Cr PHOTO-MASK with diameter and distance of 500 μm) shown in FIG. 1 was used for ultraviolet irradiation with intensity of 250mj/cm2The illumination time is 100s, and the lamp is standby.
PVDF dispersion coating
Adding 221363 g of dispersant BYKLP and 900.6 g of wetting agent BYKLP-X209into 100g of deionized water respectively, and stirring and dissolving for 30min at the speed of 300 r/min; adding 40g of PVDF (Kynar 2801) powder into the mixed solution, continuing stirring for 30min, and oscillating for 30min by using a high-speed oscillator to prepare PVDF pre-dispersion liquid; thirdly, adding 2g of SBR (styrene butadiene rubber) binder into the PVDF pre-dispersion liquid, and stirring for 30min at the speed of 300r/min to prepare the polyvinylidene fluoride dispersion liquid; coating the polyvinylidene fluoride dispersion liquid on the treated membrane by using a flat plate coating machine; and drying to obtain the dot matrix PVDF coating membrane (the thickness is 2 mu m).
Example 2
1. Coating of ceramic coating liquid
Adding 25g of alumina ceramic into 100g of deionized water, adding 0.2g of dispersant polyethylene glycol and octadecyl trimethyl ammonium chloride respectively, and stirring at a high speed of 3000r/min for 4 hours; secondly, 0.6g of sodium carboxymethylcellulose and 0.5g of polyvinylpyrrolidone are added successively and stirred until the sodium carboxymethylcellulose and the polyvinylpyrrolidone are dissolved, wherein the stirring speed is 1000 r/min; continuing to add 3g of octadecyl decyl triethoxysilane, uniformly stirring and dispersing for 4h at the stirring speed of 1000r/min to obtain a ceramic coating liquid; fourthly, coating the ceramic coating liquid on the base film by using a flat plate coating machine, drying for later use, and performing the third step and the fourth step under a light-proof condition; the thickness of the obtained ceramic separator was 16 μm.
2. Ultraviolet light irradiation
The MASK plate (PHOTO-etching chrome plate Cr PHOTO-MASK, circle diameter and interval 500 μm) shown in FIG. 1 was used for ultraviolet irradiation with intensity of 350mj/cm2 and irradiation time of 50s for standby.
PVDF dispersion coating
Adding 221363 g of dispersant BYKLP and 900.6 g of wetting agent BYKLP-X209into 100g of deionized water respectively, and stirring and dissolving for 30min at the speed of 300 r/min; adding 30g of PVDF (Kynar 2801) powder into the mixed solution, continuing stirring for 30min, and oscillating for 30min by using a high-speed oscillator to prepare PVDF pre-dispersion liquid; thirdly, adding 2g of SBR (styrene butadiene rubber) binder into the PVDF pre-dispersion liquid, and stirring for 30min at the speed of 300r/min to prepare the polyvinylidene fluoride dispersion liquid; coating the polyvinylidene fluoride dispersion liquid on the treated membrane by using a flat plate coating machine; and drying to obtain the dot matrix PVDF coating membrane (the thickness is 2 mu m).
Example 3
1. Coating of ceramic coating liquid
Adding 25g of alumina ceramic into 100g of deionized water, adding 0.2g of dispersant polyethylene glycol and octadecyl trimethyl ammonium chloride respectively, and stirring at a high speed of 3000r/min for 4 hours; secondly, 0.6g of sodium carboxymethylcellulose and 0.5g of polyvinylpyrrolidone are added successively and stirred until the sodium carboxymethylcellulose and the polyvinylpyrrolidone are dissolved, wherein the stirring speed is 1000 r/min; continuing to add 5g of heptadecafluorodecyl triethoxysilane, uniformly stirring and dispersing for 4h at the stirring speed of 1000r/min to obtain a ceramic coating liquid; fourthly, coating the ceramic coating liquid on the base film by using a flat plate coating machine, drying for later use, and performing the third step and the fourth step under a light-proof condition; the thickness of the obtained ceramic separator was 16 μm.
2. Ultraviolet light irradiation
The MASK plate (PHOTO-etching chromium plate Cr PHOTO-MASK, circle diameter and spacing of 500 μm) shown in FIG. 1 was used for ultraviolet irradiation with intensity of 500mj/cm2 and irradiation time of 2s for use.
PVDF dispersion coating
Adding 221363 g of dispersant BYKLP and 900.6 g of wetting agent BYKLP-X209into 100g of deionized water respectively, and stirring and dissolving for 30min at the speed of 300 r/min; adding 20g of PVDF (Kynar 2801) powder into the mixed solution, continuing stirring for 30min, and oscillating for 30min by using a high-speed oscillator to prepare PVDF pre-dispersion liquid; thirdly, adding 2g of SBR (styrene butadiene rubber) binder into the PVDF pre-dispersion liquid, and stirring for 30min at the speed of 300r/min to prepare the polyvinylidene fluoride dispersion liquid; coating the polyvinylidene fluoride dispersion liquid on the treated membrane by using a flat plate coating machine; and drying to obtain the dot matrix PVDF coating membrane (the thickness is 2 mu m).
Comparative example 1
1. Coating of ceramic coating liquid
Adding 25g of alumina ceramic into 100g of deionized water, adding 0.2g of dispersant polyethylene glycol and octadecyl trimethyl ammonium chloride respectively, and stirring at a high speed of 3000r/min for 4 hours; secondly, 0.6g of sodium carboxymethylcellulose and 0.5g of polyvinylpyrrolidone are added successively and stirred until the sodium carboxymethylcellulose and the polyvinylpyrrolidone are dissolved, and the stirring speed is 1000r/min, so as to obtain ceramic coating liquid; and fourthly, coating the ceramic coating liquid on the base film by using a flat coater, and drying for later use to obtain the ceramic diaphragm with the thickness of 16 microns.
PVDF dispersion coating
Adding 221363 g of dispersant BYKLP and 900.3 g of wetting agent BYKLP-X209into 100g of deionized water respectively, and stirring and dissolving for 20min at the speed of 400 r/min; adding 20g of PVDF (Kynar 2801) powder into the mixed solution, continuously stirring for 20min, and oscillating for 30min by using a high-speed oscillator to prepare PVDF pre-dispersion liquid; thirdly, adding 2g of SBR (styrene butadiene rubber) binder into the PVDF pre-dispersion liquid, and stirring for 20min at a speed of 400r/min to prepare the polyvinylidene fluoride dispersion liquid; and fourthly, spin-coating the polyvinylidene fluoride dispersion liquid on a ceramic diaphragm (16 mu m) in a rotary spraying mode to obtain a dot matrix PVDF coating diaphragm (the thickness is 2 mu m).
Test 1
The air permeability of the membranes was tested using a gurley air permeability tester, the lattice PVDF coated membranes prepared in examples 1-3 and comparative example 1 were cut into square squares of about 200mm, and the time required for 100cc of air to permeate the membrane was recorded using a gurley air permeability tester, with the results shown in table 1:
TABLE 1
| Sample (I) | Example 1 | Example 2 | Example 3 | Comparative example 1 |
| Gurley(s/100ml) | 241 | 239 | 234 | 237 |
As can be seen from Table 1, the lattice PVDF coating membrane prepared by the method of the invention has good air permeability.
Testing the adhesive force: a diaphragm with a complete film surface and no abnormal appearance is taken, a sample with the width of 25mm and the length of 100mm is punched, two punched diaphragm samples are taken and stacked together, hot pressing is carried out on the diaphragm samples for 30min on a hot press under the conditions of the pressure of 3MPa and the temperature of 80 ℃, and the tension of the two diaphragms bonded together is tested by a tension machine, the speed is 1m/min, and the unit of the bonding strength is N/m. The results are shown in table 2:
TABLE 2
| Sample (I) | Example 1 | Example 2 | Example 3 | Comparative example 1 |
| Adhesive force N/m | 6.22 | 5.86 | 4.78 | 5.45 |
As can be seen from Table 2, the dot matrix PVDF coating membrane prepared by the method of the invention has good binding power.
The lattice PVDF coating membranes prepared in examples 1-3 and comparative example 1 are respectively used for preparing flexible package lithium ion batteries, then the prepared flexible package lithium ion batteries are charged and discharged at normal temperature by adopting 1C rate, the cycle is carried out for 600 times, and the battery capacity before and after the cycle is recorded. The capacity retention after N cycles (the battery capacity after N cycles/the battery capacity before cycles) × 100%, the results are shown in table 3:
TABLE 3
| Sample (I) | Example 1 | Example 2 | Example 3 | Comparative example 1 |
| Capacity retention ratio% | 95.18 | 94.24 | 94.67 | 94.82 |
As can be seen from Table 3, the lithium battery capacity retention rate of the dot matrix PVDF coating membrane prepared by the method is high.
According to the preparation method of the battery diaphragm, the problems of hole blocking and needle blocking in spraying are solved by adding the hydrophobic substance into the ceramic formula; the PVDF can be coated in a dot matrix manner only by a traditional coating mode, so that high-price equipment is avoided, and the cost is saved. The dot matrix PVDF coating membrane prepared by the method has the same or better performance than the existing dot matrix PVDF spraying membrane, and meets the market demand. The method is simple and feasible, and can be used for producing the dot matrix PVDF coating diaphragm in a large scale.
Claims (9)
1. A preparation method of a battery separator is characterized by comprising the following steps:
s1: coating a ceramic coating liquid containing a hydrophobic substance on a base film under a light-proof condition to obtain a ceramic diaphragm, wherein the hydrophobic substance is fluorosilane or alkyl ketene dimer;
s2: covering a mask with a pattern on the ceramic diaphragm obtained in the step S1, and performing ultraviolet irradiation to obtain the ceramic diaphragm with a hydrophilic part and a hydrophobic part;
s3: and (5) coating polyvinylidene fluoride dispersion liquid on the ceramic diaphragm obtained in the step (S2), and drying to obtain the polyvinylidene fluoride coated diaphragm distributed in a lattice manner, wherein the solvent of the polyvinylidene fluoride dispersion liquid is deionized water.
2. The method for preparing a battery separator according to claim 1, wherein the ceramic coating solution containing a hydrophobic substance in S1 comprises: based on 100wt% of solvent, 20-30wt% of alumina ceramic, 0.2-0.8wt% of dispersant, 0.5-2wt% of binder, 0.2-1wt% of thickener and 1-5wt% of hydrophobic substance.
3. The method for preparing the battery separator according to claim 2, wherein the solvent is deionized water; the dispersing agent is polyethylene glycol and octadecyl trimethyl ammonium chloride; the binder is polyvinylpyrrolidone; the thickening agent is sodium carboxymethyl cellulose.
4. The method for preparing a battery separator according to claim 3, wherein the fluorosilane is tridecafluorooctyltriethoxysilane, heptadecafluorodecyltriethoxysilane or octadecyldecyltriethoxysilane.
5. The method for preparing the battery separator according to claim 1, wherein the mask in S2 comprises a substrate and a light-tight layer, wherein the substrate is quartz glass, and the light-tight layer is a chromium layer plated on the surface of the substrate by a sputtering method; the pattern on the mask in the S2 is a circular hole, and is obtained by a wet etching mode, wherein the diameter of the circular hole is 200 mu m-1mm, and the distance is 200 mu m-1 mm.
6. The method for preparing a battery separator according to claim 1, wherein the polyvinylidene fluoride dispersion liquid of S3 comprises: calculated by taking the solvent as 100wt%, 20-40wt% of polyvinylidene fluoride, 1-5wt% of dispersing agent, 1-5wt% of binder and 0.2-1.0wt% of wetting agent.
7. The method for preparing the battery separator according to claim 6, wherein the polyvinylidene fluoride is a polyvinylidene fluoride homopolymer or a polyvinylidene fluoride copolymer; the dispersant and the binder are water-soluble polymers.
8. The method for preparing the battery separator according to claim 6, wherein the dispersant is sodium dodecyl benzene sulfate or polyacrylate; the binder is styrene butadiene rubber, polyvinylpyrrolidone, acrylates or polyvinyl alcohol; the wetting agent is a polyether silicone copolymer.
9. The method for preparing the battery separator according to claim 1, wherein the polyvinylidene fluoride dispersion liquid of S3 is prepared by the following steps: (1) adding a dispersing agent and a wetting agent into deionized water, and stirring for dissolving; (2) adding polyvinylidene fluoride into the mixture, continuously stirring the mixture, and oscillating the mixture by using a high-speed oscillator to prepare polyvinylidene fluoride pre-dispersion liquid; (3) and adding the binder into the polyvinylidene fluoride pre-dispersion liquid, and stirring.
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| CN201910341649.2A CN110148695B (en) | 2019-04-26 | 2019-04-26 | Preparation method of battery diaphragm |
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| CN201910341649.2A CN110148695B (en) | 2019-04-26 | 2019-04-26 | Preparation method of battery diaphragm |
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| CN110148695A CN110148695A (en) | 2019-08-20 |
| CN110148695B true CN110148695B (en) | 2020-12-29 |
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| CN114153013A (en) * | 2020-09-07 | 2022-03-08 | 合肥工业大学 | Preparation method of micro lens array and micro lens array |
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| CN104993088B (en) * | 2015-07-14 | 2017-06-06 | 华南理工大学 | The non-woven fabric type lithium battery diaphragm and preparation method of a kind of low temperature closed pore high-temperature stable |
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Denomination of invention: A preparation method of battery separator Effective date of registration: 20220930 Granted publication date: 20201229 Pledgee: Dongguan Rural Commercial Bank Co.,Ltd. Chang'an sub branch Pledgor: DONGGUAN HEC TECH R&D Co.,Ltd. Registration number: Y2022980017245 |