CN112670662B - Method for coating ceramic particles with polymer and application thereof - Google Patents
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Abstract
The invention provides a method for coating ceramic particles with a polymer and application thereof. The method comprises the following steps: dispersing ceramic particles in an organic solvent, adding a coupling agent, and dispersing to form a first dispersion liquid; dissolving the first polymer and the second polymer in an organic solvent to form a second dispersion liquid; reacting the first dispersion with the second dispersion to form a third dispersion; mixing a first dispersant, an organic solvent and water to form a base solution; and simultaneously dripping the aqueous solutions of the third dispersion and the second dispersion into the base solution, wherein the water-oil ratio of the aqueous solutions of the third dispersion and the second dispersion is the same as that of the base solution. The coating method provided by the invention adopts a 'balanced injection method' to prepare the dispersion liquid of the polymer-coated ceramic particles, and controls the speed of polymer phase separation by the mass ratio of the water solution of the third dispersion liquid and the second dispersion agent to the equal water-oil mass of the base solution, so as to avoid rapid phase separation flocculation and further ensure the particle size uniformity of the polymer-coated ceramic particles.
Description
Technical Field
The invention relates to the technical field of ceramic particle coating, in particular to a method for coating ceramic particles by using a polymer and application thereof.
Background
The diaphragm is one of important materials for manufacturing the lithium ion battery, and has the function of separating a positive electrode and a negative electrode in the battery so as to prevent short circuit; meanwhile, the porous structure also has the function of electrolyte ions to pass through. At present, in order to achieve high safety and electrochemical stability, the surface of the separator is generally provided with a ceramic coating layer formed by inorganic oxide powder and a fluoropolymer coating layer, for example, a water-based paint containing ceramic particles is firstly coated on the surface of a Polyethylene (PE)/polypropylene (PP) porous base membrane, and then the fluoropolymer coating layer is continuously coated on the surface or the opposite side of the ceramic coating layer.
In the method for preparing the ceramic coating at the present stage, the water-based binder and the inorganic oxide powder are fully dispersed into ceramic slurry under the action of the dispersant, and the ceramic slurry is coated on the surface of the base film and dried to form the ceramic coating. The ceramic coating can play a mechanical supporting role for the PE/PP porous base membrane, effectively reduces the thermal shrinkage proportion of the diaphragm, but does not have the functions of bonding with a pole piece and swelling in electrolyte. Then, the polymer coating is coated on the surface of the ceramic coating diaphragm, so that the thermal stability of the ceramic diaphragm is further kept on the premise of realizing the pole piece bonding function. However, forming the ceramic coating layer first and then applying the polymer coating layer requires at least one additional coating process, increases coating production costs, and affects yield. Therefore, researchers often achieve the function of a coating while reducing the number of coating process steps by a method of coating inorganic particles with a polymer. In the process of coating inorganic particles with synthetic polymer, the phase transfer dispersion method is usually the main method. However, the phase transfer dispersion method generally suffers from the influence of transfer rate, time and the like, so that the polymer precipitation rate is uncontrollable, and flocculation occurs.
Disclosure of Invention
The present invention has been completed based on the following findings of the inventors:
the inventor of the invention finds that, compared with the conventional phase transfer dispersion coating method of directly injecting an oil phase into a water phase, the dispersion liquid of the polymer-coated ceramic particles can be prepared by adopting a 'balanced injection method', so that the stability of the water-oil ratio of the injection environment is ensured, and the phase separation and precipitation speed of the polymer can be controlled by controlling the equal water-oil ratio of the dropping liquid and the base liquid, thereby avoiding the problem of dispersion failure caused by rapid phase separation flocculation, and further ensuring the particle size uniformity of the polymer-coated ceramic particles in the polymer-coated ceramic particle suspension in the dispersion process.
In a first aspect of the invention, a method of polymer coating ceramic particles is provided.
According to an embodiment of the invention, the method comprises: (1) Dispersing ceramic particles in an organic solvent, adding a coupling agent, and dispersing to form a first dispersion liquid; (2) Dissolving the first polymer and the second polymer in an organic solvent to form a second dispersion liquid; (3) Reacting the first dispersion with the second dispersion to form a third dispersion; (4) Mixing a first dispersant, an organic solvent and water to form a base solution; (5) And simultaneously dripping the aqueous solutions of the third dispersion liquid and the second dispersion liquid into the base liquid, wherein the water-oil mass ratio of the aqueous solutions of the third dispersion liquid and the second dispersion liquid is the same as that of the base liquid, so as to obtain the suspension of the polymer-coated ceramic particles.
By adopting the coating method of the embodiment of the invention, the method of simultaneously adding two dropping liquids of the third dispersion liquid and the aqueous solution of the second dispersant into the base solution is the 'equilibrium injection method'. The suspension of the polymer-coated ceramic particles is prepared by adopting a balanced injection method, and the speed of phase separation and precipitation of the polymer can be controlled by controlling the water-oil ratio of the dropping liquid to the base liquid, so that the problem of dispersion failure caused by rapid phase separation flocculation is avoided, and the particle size uniformity of the polymer-coated ceramic particles in the suspension of the polymer-coated ceramic particles is further ensured.
In addition, the method according to the above embodiment of the present invention may further have the following additional technical features:
according to an embodiment of the present invention, the material of the ceramic particles is at least one of alumina, hydrated alumina, silica, titania, barium sulfate, magnesium oxide, and magnesium hydroxide; the coupling agent is a silane coupling agent.
According to an embodiment of the present invention, the organic solvent is at least one of N, N-dimethylacetamide, N-dimethylformamide, acetone, or N-methylpyrrolidone, and at least one of ethyl acetate, butyl acetate, tributyl phosphate, and dibutyl phthalate; the first dispersant and the second dispersant are respectively polyvinyl alcohol.
According to an embodiment of the present invention, the first polymer is at least one of polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene copolymer, and the second polymer is at least one of polyacrylonitrile, polyacrylic acid, and polyacrylate copolymer.
According to an embodiment of the invention, the molar ratio of the first polymer to the second polymer is 1: (0.1 to 0.5).
According to the embodiment of the invention, the temperature of the reaction is 35-60 ℃ and the stirring time is 0.5-2 hours.
According to the embodiment of the invention, the dripping time is 0.5 to 3 hours, the temperature is 35 to 60 ℃, and the stirring speed is 2500 to 3500r/min.
According to the embodiment of the invention, the water-oil mass ratio is 7:3 to 9: 1.
According to an embodiment of the invention, the method further comprises: and further washing, concentrating and drying the suspension obtained after dropwise adding to obtain the polymer-coated ceramic particles.
In a second aspect of the invention, a separator for a lithium ion battery is provided.
According to an embodiment of the present invention, the separator includes a separator body, the surface of the separator body is coated with a composite ceramic coating, and the raw material for forming the composite ceramic coating includes uncoated ceramic particles and polymer-coated ceramic particles prepared by the above method.
According to the diaphragm of the lithium ion battery provided by the embodiment of the invention, the uncoated ceramic particles and the polymer-coated ceramic particles prepared by the balanced injection method are mixed and coated on the diaphragm body to form the composite ceramic coating, so that the diaphragm of the lithium ion battery has higher air permeability, higher thermal bonding property and higher thermal stability. It will be understood by those skilled in the art that the features and advantages described above with respect to the method of polymer coating ceramic particles are still applicable to the separator of the lithium ion battery and will not be described in detail herein.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The foregoing aspects of the invention are explained in the description of the embodiments with reference to the following drawings, in which:
FIG. 1 is a schematic flow chart of a method of polymer coating ceramic particles according to one embodiment of the present invention;
fig. 2 is an electron micrograph of the polymer-coated ceramic particles of example 1 of the present invention forming a composite ceramic coating on the separator body.
Detailed Description
The following examples are set forth in order to illustrate the present invention and should not be construed as limiting the invention, as will be understood by those skilled in the art. Unless otherwise indicated, specific techniques or conditions are not explicitly described in the following examples, and those skilled in the art may follow techniques or conditions commonly employed in the art or in accordance with the product specifications.
In one aspect of the invention, a method of polymer coating ceramic particles is provided. According to an embodiment of the present invention, referring to fig. 1, the cladding method includes:
s100: the ceramic particles are dispersed in an organic solvent and a coupling agent is added to form a first dispersion.
In this step, ceramic particles are dispersed in an organic solvent and a coupling agent is added to form a first dispersion liquid a.
According to an embodiment of the present invention, the material of the ceramic particles may be alumina (Al) 2 O 3 ) Alumina hydrate (AlOOH), silicon dioxide (SiO) 2 ) Titanium dioxide (TiO) 2 ) Barium sulfate (BaSO) 4 ) Magnesium oxide (MgO) and magnesium hydroxide (Mg (OH) 2 ) At least one of them. In some embodiments of the present invention, the coupling agent may be selected from silane coupling agents, which may provide a stronger bond to the ceramic particles after the polymer coating.
According to an embodiment of the present invention, the organic solvent may be at least one of N, N-dimethylacetamide, N-dimethylformamide, acetone, or N-methylpyrrolidone, and at least one of ethyl acetate, butyl acetate, tributyl phosphate (TBP), and dibutyl phthalate (DBP).
S200: the first polymer and the second polymer are dissolved in an organic solvent to form a second dispersion liquid.
In this step, the first polymer P1 and the second polymer P2 are dissolved in an organic solvent to form a second dispersion liquid B. Thus, two polymers with different properties can be specially selected for the polymer coating the ceramic particles, so that the ceramic particles coated by the polymer can have chemical stability, swelling performance and hot-pressing adhesion.
According to an embodiment of the present invention, the first polymer P1 may be at least one of polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and the second polymer P2 may be at least one of Polyacrylonitrile (PAN), polyacrylic acid, and polyacrylate copolymer. Thus, the use of the first polymer P1 of the above kind has excellent chemical stability, while the second polymer P2 of the above kind has a lower softening point, so that blending can further lower the softening point of the mixture, and thus the thermal bonding temperature of the polymer-coated ceramic particles.
In some embodiments of the invention, the molar ratio of the first polymer to the second polymer may be 1: (0.1 to 0.5), specifically 1:0.1 or 1:0.5, and the like, by adjusting the proportion of the two polymers, the polymer-coated ceramic particles not only have good chemical stability, but also have controllable swelling performance, and have better thermal bonding performance with the lithium ion battery anode material at lower temperature (lower than or equal to 80 ℃). Moreover, if the molar ratio of the first polymer to the second polymer is higher than 1:0.5 is that the thermal bonding performance of the diaphragm and the pole piece is poor at low temperature, and the electrochemical stability of the diaphragm is poor; if the molar ratio is less than 1: at 0.1, the swelling of the polymer was severe, and the internal resistance of the battery was high.
S300: and reacting the first dispersion liquid with the second dispersion liquid to form a third dispersion liquid.
In this step, the first dispersion liquid a of step S100 and the second dispersion liquid B of step S200 are reacted to form a third dispersion liquid C. In some embodiments of the present invention, the reaction temperature may be 35 to 60 ℃ and the stirring time may be 0.5 to 2 hours, so that the silane coupling agent may better bond the polymer as the shell and the ceramic particles as the core through chemical bonds.
S400: the first dispersant, organic solvent and water are mixed to form a base solution.
In this step, a first dispersant, an organic solvent and water are mixed to form a base solution D. The first dispersant is polyvinyl alcohol (PVA), and thus, the emulsion system is better stabilized.
S500: and simultaneously dripping the third dispersion liquid and the aqueous solution of the second dispersing agent into the base liquid.
In this step, the third dispersion liquid C of step S300 and the aqueous solution of the second dispersant are simultaneously added dropwise to the base liquid D of step S400, and the water-oil mass ratio of the aqueous solutions of the third dispersion liquid C and the second dispersant is the same as the water-oil ratio of the base liquid C, to obtain a suspension G of polymer-coated ceramic particles. Controlling the particle size test range of the polymer-coated ceramic particles in the suspension G: d 10 <0.5μm，D 50 <1.0μm，D 90 <5.0 mu. Thus, the prepared polymer-coated ceramic particles have both the thermal stability of inorganic particles and the surface property-thermocompression bondability of organic particles.
In this step, the second dispersant is polyvinyl alcohol (PVA), and thus, the emulsion system can be more stabilized.
In addition, the inventor of the present invention has also found through research that, compared with the conventional phase transfer dispersion coating method of directly injecting an oil phase into a water phase, a "balanced injection method" can be adopted to prepare a dispersion liquid of polymer-coated ceramic particles, so that the stability of the water-oil ratio of the injection environment is ensured, and the phase separation and precipitation speed of the polymer can be controlled by controlling the equal water-oil ratio of the dropping liquid and the base liquid, thereby avoiding the problem of dispersion failure caused by rapid phase separation flocculation, and further ensuring the particle size uniformity of the polymer-coated ceramic particles in the dispersion process. In some embodiments of the invention, the water to oil mass ratio of the third dispersion to the aqueous solution of the second dispersant and the water to oil mass ratio of the base C may be in the range of 7:3 to 9:1, such as 7.
Wherein, the mass ratio of water to oil refers to the mass ratio of water to organic matters in a solution system. Specifically, the method comprises the following steps: the water-oil mass ratio of the base liquid C means the mass ratio between the total mass of water and the water contained in the first dispersing agent and the total mass of the organic solvent and the organic matter contained in the first dispersing agent; the water-oil mass ratio of the aqueous solution of the third dispersion to the aqueous solution of the second dispersion means a mass ratio of the total mass of water contained in the third dispersion and the second dispersion to the total mass of the organic solvent and the organic substances contained in the third dispersion and the second dispersion.
The specific reagents for the organic solvents used in the above steps may be the same or different, and the organic solvents used in the steps may be at least one of N, N-dimethylacetamide, N-dimethylformamide, acetone, or N-methylpyrrolidone, and at least one of ethyl acetate, butyl acetate, tributyl phosphate (TBP), and dibutyl phthalate (DBP).
In some specific examples, after step S500, the coating method may further include:
s600: and further washing, concentrating and drying the suspension obtained after dropwise adding to obtain the polymer-coated ceramic particles.
In this step, the suspension G of polymer-coated ceramic particles of step S500 is continuously washed with water and concentrated and dried, and thus, the organic solvent can be removed and concentrated and dried by washing with a large amount of deionized water by the sedimentation water washing method or ultrafiltration washing method, thereby obtaining polymer-coated ceramic particles H.
In summary, according to the embodiments of the present invention, the present invention provides a coating method, in which a "balanced injection method" is used to prepare a dispersion of polymer-coated ceramic particles, and the speed of polymer phase separation can be controlled by controlling the water-oil ratio of the dropping liquid to the base liquid, so as to avoid the dispersion failure problem caused by rapid phase separation flocculation, and further ensure the particle size uniformity of the polymer-coated ceramic particles.
In another aspect of the invention, a separator for a lithium ion battery is provided.
According to an embodiment of the present invention, a separator includes a separator body, a surface of the separator body is coated with a composite ceramic coating layer, and raw materials for forming the composite ceramic coating layer include uncoated ceramic particles and polymer-coated ceramic particles prepared by the above-described method. Thus, after the inorganic ceramic particles coated with the polymer and the inorganic ceramic particles which are not coated with the polymer are mixed, the diaphragm coating of the lithium ion battery with low air permeability, high thermal caking property and high thermal stability can be prepared in a one-time coating mode.
In some embodiments of the present invention, in the aqueous slurry applied to form the composite ceramic coating, a dispersant, a binder, and a surfactant may be added in addition to the uncoated ceramic particles and the polymer-coated ceramic particles, so that the surface of the composite ceramic coating on the separator body may be smoother, the thickness may be more uniform, and the bonding force may be stronger. In some specific examples, the aqueous coating may be applied to one or both sides of a separator of Polyolefin (PO) to form a separator of a low heat shrinkage lithium ion battery after drying.
In summary, according to the embodiments of the present invention, the present invention provides a lithium ion battery separator, in which uncoated ceramic particles and polymer-coated ceramic particles prepared by a "balanced injection method" are mixed and coated on a separator body to form a composite ceramic coating, so that the lithium ion battery separator has higher air permeability, higher thermal adhesiveness and higher thermal stability. It will be understood by those skilled in the art that the features and advantages described above with respect to the method of polymer coating ceramic particles are still applicable to the separator of the lithium ion battery and will not be described in detail herein.
The invention has the following advantages: (1) The former polymer coating process of 'water oiling' is changed, a 'balance injection method' is adopted to prepare suspension of a polymer coating material, and the environmental stability of the dispersion process is ensured by controlling the water-oil ratio of the injection environment. (2) The second polymer P2 with a lower softening point and the first polymer P1 with good chemical stability are selected, and the coating material formed by blending the two polymers has the double advantages of controllable softening point and good thermal stability. (3) The swelling proportion of the mixed coating electrolyte of the inorganic ceramic particles coated by the polymer and the ceramic particles is moderate, so that the pore blockage of a single polymer coating is avoided, the porosity of the diaphragm is high, and the lithium ion conduction effect is good. (4) The diaphragm made of the double-polymer coated ceramic particles can realize thermal bonding with the pole piece at low temperature (lower than or equal to 80 ℃) and has excellent thermal stability; (5) The coating with inorganic ceramic particles and polymer material is coated at one time, and the coating processing cost is low.
The invention will now be described with reference to specific examples, which are intended to be illustrative only and not to be limiting in any way.
Example 1
In this example, polymer-coated ceramic particles were prepared. The method comprises the following specific steps:
(1) Adding 8g of aluminum oxide into 60g of N, N-dimethylacetamide, adding 0.1g of silane coupling agent, and stirring for reaction for 1 hour to obtain modified ceramic particle dispersion liquid A;
(2) Adding 10g of PVDF-HFP copolymer and polyacrylate copolymer into 40g of N, N-dimethylacetamide to dissolve to obtain a double-copolymer solution B, wherein the molar ratio of the PVDF-HFP copolymer to the polyacrylate copolymer is 1;
(3) The copolymer solution B was mixed with the dispersion A at 60 ℃ and reacted in an oil bath for 0.5 hour to form a polymer-coated ceramic particle dispersion C.
(4) Preparing a base solution D after mixing N, N-dimethylacetamide, PVA and water, wherein the water-oil mass ratio is 2. Wherein the mass ratio of the N, N-dimethylacetamide to the PVA to the water is 2.1.
(5) The "equilibrium injection method" achieves phase transfer: the dispersion C and the aqueous solution of PVA were added to the base solution D at the same time in the same ratio of water to oil of 2.
(6) And further washing, concentrating and drying the suspension G to form the target product polymer-coated ceramic particles H.
Example 2
In this example, polymer-coated ceramic particles were prepared. The method comprises the following specific steps:
(1) Adding 8g of aluminum oxide into 60g of N, N-dimethylacetamide, adding 0.1g of silane coupling agent, and stirring for reaction for 0.5h to obtain modified ceramic particle dispersion liquid A;
(2) Adding 10g of PVDF-HFP copolymer and polyacrylate copolymer into 40g of N, N-dimethylacetamide to dissolve to obtain a double-copolymer solution B, wherein the molar ratio of the PVDF-HFP copolymer to the polyacrylate copolymer is 1;
(3) The copolymer solution B was mixed with the dispersion A at 35 ℃ and reacted in an oil bath for 3 hours to form a polymer-coated ceramic particle dispersion C.
(4) Preparing a base solution D mixed by N, N-dimethylacetamide, PVA and water, wherein the water-oil mass ratio is 2. Wherein the specific mass ratio of the N, N-dimethylacetamide to the PVA to the water is 2.1.
(5) The "equilibrium injection method" achieves phase transfer: and (3) simultaneously adding the dispersion liquid C and the PVA aqueous solution into the base liquid D according to the same water-oil mass ratio of 2.
(6) And further washing, concentrating and drying the suspension G to form the target product polymer-coated ceramic particles H.
Comparative example 1
In this comparative example, polymer-coated ceramic particles were produced in substantially the same manner and under substantially the same conditions as in example 1. The difference is that in this comparative example: (4) phase transfer: and directly adding the dispersion liquid C into an aqueous solution of PVA at the temperature of 60 ℃ for 0.5 hour to form a suspension G of the polymer-coated ceramic particles.
Comparative example 2
In this comparative example, polymer-coated ceramic particles were produced in substantially the same manner and under substantially the same conditions as in example 2. The difference is that in this comparative example: (4) phase transfer: and directly adding the dispersion liquid C into an aqueous solution of PVA at the temperature of 35 ℃ for 3 hours to form a suspension G of the polymer-coated ceramic particles.
To summarize
Firstly, mixing the polymer-coated ceramic particles of examples 1 to 2 and comparative example 1 with uncoated aluminum oxide particles, but not mixing the polymer-coated ceramic particles of comparative example 2 with uncoated aluminum oxide particles, respectively adding a dispersant, a surfactant and an adhesive to prepare aqueous slurry of the polymer-coated ceramic particles, respectively coating the aqueous slurry on one side of a polyolefin diaphragm, and drying the aqueous slurry to form the diaphragm of the lithium ion battery.
And continuously testing the diaphragm of each group of lithium ion batteries by using the data such as the particle size of the coating liquid, the air permeability of the diaphragm, the stripping force, the thermal shrinkage and the like.
Wherein, the particle size test of the coating liquid: taking about 10mL of a uniformly stirred sample, after a laser particle analyzer testing system is stable, entering a 'testing system' in a computer system toolbar, entering a computer testing system interface, and selecting a corresponding medium from option-substance Chinese names; then spot test-ultrasound-cycle (cycle 1 minute and second for 10 seconds, so cycle 3-4 times); then carrying out background calibration; adding the sample by a dropper under the ultrasonic circulation till the refractive index is between 10 and 15; the data is continuously tested and saved. Taking data of successive tests, recording D therein 10 、D 50 、D 90 . Each sample was run in duplicate and the test results averaged.
Testing the air permeability value of the diaphragm: selecting a diaphragm flat part, cutting each to-be-tested product into 3 pieces of samples of 100mm multiplied by 100mm, and clamping the samples between an upper testing cavity and a lower testing cavity of a permeability tester. The air permeability of the ceramic separator was measured by the time that 100mL of air was passed through a certain area of the separator under a certain pressure at an ambient temperature of 25 ℃.
And (3) testing the stripping force of the separator and the electrode: selecting a diaphragm flattening part, cutting each to-be-tested product into a sample of 25mm multiplied by 500mm, carrying out hot pressing on the diaphragm sample and the positive pole piece for 1min under the conditions of 1Mpa and 80 ℃, and then testing the 180-degree stripping force.
Testing the thermal shrinkage rate of the diaphragm: the high-temperature resistance of a ceramic coating film sample is represented by adopting the thermal shrinkage rate, three sample sheets of 12cm multiplied by 12cm are cut, two lines which are perpendicular to each other and have the length of about 10cm are drawn in the middle of the sample sheets and indicate the MD and TD directions, the length of the two lines is measured and recorded by adopting an Abbe's comparator, and the diaphragm is placed in heat insulation paper to prevent the diaphragm from directly contacting the inner wall of an oven. And placing the sample in an oven reaching the set temperature for a specified time, taking out the sample, cooling to room temperature, measuring and recording the lengths of the two lines by using an Abbe's comparator, and calculating the thermal shrinkage rate according to the length change of the two lines before and after baking. Shrinkage factor = (L) 0 —L 1 )/L 0 ×100%。
The test results of the separators of the lithium ion batteries of examples 1 to 2 and comparative examples 1 to 2 are shown in table 1. Fig. 2 is an electron micrograph of the separator of the lithium ion battery of example 1.
TABLE 1 test results of various performances of separators of lithium ion batteries of examples 1 to 2 and comparative examples 1 to 2
In the description of the present invention, the terms "first", "second", and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of the feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise.
In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and that changes, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (9)
1. A method of polymer coating ceramic particles, comprising:
(1) Dispersing ceramic particles in an organic solvent, adding a coupling agent, and dispersing to form a first dispersion liquid;
(2) Dissolving the first polymer and the second polymer in an organic solvent to form a second dispersion liquid;
(3) Reacting the first dispersion with the second dispersion to form a third dispersion;
(4) Mixing a first dispersant, an organic solvent and water to form a base solution;
(5) Simultaneously dropping the aqueous solutions of the third dispersion and the second dispersion into the base solution, wherein the water-oil mass ratio of the aqueous solutions of the third dispersion and the second dispersion is the same as the water-oil mass ratio of the base solution, so as to obtain a suspension of the polymer-coated ceramic particles,
the water-oil mass ratio of the aqueous solution of the third dispersion liquid to the aqueous solution of the second dispersion liquid is a ratio of the total mass of water contained in the third dispersion liquid and water contained in the aqueous solution of the second dispersion liquid to the total mass of organic matter contained in the third dispersion liquid and organic matter contained in the second dispersion liquid;
the water-oil mass ratio of the base solution is the ratio of the total mass of the water contained in the first dispersing agent and the water added in the step (4) to the total mass of the organic matter contained in the first dispersing agent and the organic solvent added in the step (4);
the first polymer is at least one of polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene copolymer, the second polymer is at least one of polyacrylonitrile, polyacrylic acid and polyacrylate copolymer,
the first dispersant and the second dispersant are polyvinyl alcohol respectively.
2. The method of claim 1, wherein the ceramic particles are made of a material selected from at least one of alumina, hydrated alumina, silica, titania, barium sulfate, magnesium oxide, and magnesium hydroxide; the coupling agent is a silane coupling agent.
3. The method according to claim 1, wherein the organic solvent is at least one of N, N-dimethylacetamide, N-dimethylformamide, acetone, or N-methylpyrrolidone, and at least one of ethyl acetate, butyl acetate, tributyl phosphate, and dibutyl phthalate.
4. The method of claim 1, wherein the molar ratio of the first polymer to the second polymer is 1: (0.1 to 0.5).
5. The process according to claim 1, characterized in that the reaction conditions are: the temperature is 35 to 60 ℃, and the stirring time is 0.5 to 2 hours.
6. The method according to claim 1, wherein the dropping conditions are: the time is 0.5 to 3 hours, the temperature is 35 to 60 ℃, and the stirring speed is 2500 to 3500r/min.
7. The method of claim 1, wherein the water to oil mass ratio is between 7:3 to 9: 1.
8. The method of claim 1, further comprising:
and further washing, concentrating and drying the suspension obtained after the dropwise addition to obtain the polymer-coated ceramic particles.
9. A diaphragm of a lithium ion battery is characterized by comprising a diaphragm body, wherein a composite ceramic coating is formed on the surface of the diaphragm body in a coating manner, and raw materials for forming the composite ceramic coating comprise uncoated ceramic particles and the polymer-coated ceramic particles obtained in any one of claims 1 to 8.
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| CN109037564A (en) * | 2018-08-23 | 2018-12-18 | 上海三瑞高分子材料股份有限公司 | A kind of coating of lithium-ion battery diaphragm ceramic slurry and preparation method thereof |
| CN109103397A (en) * | 2018-09-28 | 2018-12-28 | 河南福森新能源科技有限公司 | A kind of preparation method of lithium ion battery ceramic coating membrane |
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Address after: 072150 No. 6, Jianye Road, Mancheng Economic Development Zone, Mancheng District, Baoding City, Hebei Province Patentee after: LUCKY FILM Co.,Ltd. Address before: 071054 No.6, Lekai South Street, Jingxiu District, Baoding City, Hebei Province Patentee before: LUCKY FILM Co.,Ltd. |