CN114614199A - Diaphragm and preparation method and application thereof - Google Patents
Diaphragm and preparation method and application thereof Download PDFInfo
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- CN114614199A CN114614199A CN202210314007.5A CN202210314007A CN114614199A CN 114614199 A CN114614199 A CN 114614199A CN 202210314007 A CN202210314007 A CN 202210314007A CN 114614199 A CN114614199 A CN 114614199A
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- polytriphenylamine
- diaphragm
- additive
- mixed solution
- combination
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- 238000002360 preparation method Methods 0.000 title abstract description 15
- 239000000919 ceramic Substances 0.000 claims abstract description 48
- 229920000327 poly(triphenylamine) polymer Polymers 0.000 claims abstract description 45
- 239000000654 additive Substances 0.000 claims abstract description 27
- 239000002002 slurry Substances 0.000 claims abstract description 27
- 230000000996 additive effect Effects 0.000 claims abstract description 26
- 239000011259 mixed solution Substances 0.000 claims abstract description 23
- 239000011248 coating agent Substances 0.000 claims abstract description 18
- 238000000576 coating method Methods 0.000 claims abstract description 18
- 239000002245 particle Substances 0.000 claims abstract description 18
- 238000002156 mixing Methods 0.000 claims abstract description 17
- 238000001035 drying Methods 0.000 claims abstract description 12
- 239000000843 powder Substances 0.000 claims abstract description 9
- 239000011230 binding agent Substances 0.000 claims abstract description 7
- 239000002270 dispersing agent Substances 0.000 claims abstract description 7
- 239000002562 thickening agent Substances 0.000 claims abstract description 7
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910001416 lithium ion Inorganic materials 0.000 claims abstract description 6
- 239000002904 solvent Substances 0.000 claims abstract description 5
- 238000003756 stirring Methods 0.000 claims description 30
- 238000000034 method Methods 0.000 claims description 13
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 claims description 11
- 229920002125 Sokalan® Polymers 0.000 claims description 10
- 229910001593 boehmite Inorganic materials 0.000 claims description 10
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 claims description 10
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 9
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 9
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 claims description 9
- 239000007787 solid Substances 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 239000002253 acid Substances 0.000 claims description 7
- 150000003863 ammonium salts Chemical class 0.000 claims description 7
- 229920000642 polymer Polymers 0.000 claims description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- 239000004584 polyacrylic acid Substances 0.000 claims description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 3
- 229920003048 styrene butadiene rubber Polymers 0.000 claims description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 2
- 239000004760 aramid Substances 0.000 claims description 2
- 229920003235 aromatic polyamide Polymers 0.000 claims description 2
- 239000008367 deionised water Substances 0.000 claims description 2
- 229910021641 deionized water Inorganic materials 0.000 claims description 2
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 claims description 2
- 239000000347 magnesium hydroxide Substances 0.000 claims description 2
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims description 2
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 claims description 2
- 229920001690 polydopamine Polymers 0.000 claims description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims description 2
- 239000002356 single layer Substances 0.000 claims description 2
- 239000011734 sodium Substances 0.000 claims description 2
- 229910052708 sodium Inorganic materials 0.000 claims description 2
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 claims description 2
- 239000004743 Polypropylene Substances 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 claims 1
- -1 polypropylene ammonium Polymers 0.000 claims 1
- 239000003792 electrolyte Substances 0.000 abstract description 16
- 150000002500 ions Chemical class 0.000 abstract description 5
- 230000007774 longterm Effects 0.000 abstract description 3
- 239000007788 liquid Substances 0.000 description 26
- 239000006185 dispersion Substances 0.000 description 22
- 230000014759 maintenance of location Effects 0.000 description 10
- 238000007581 slurry coating method Methods 0.000 description 7
- 238000010521 absorption reaction Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 230000005540 biological transmission Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000010410 layer Substances 0.000 description 5
- 238000005524 ceramic coating Methods 0.000 description 4
- 239000011521 glass Substances 0.000 description 4
- 239000011165 3D composite Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 230000008595 infiltration Effects 0.000 description 3
- 238000001764 infiltration Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 2
- 239000002390 adhesive tape Substances 0.000 description 2
- 150000001450 anions Chemical class 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 229920000058 polyacrylate Polymers 0.000 description 2
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 2
- 238000006479 redox reaction Methods 0.000 description 2
- 230000002441 reversible effect Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 239000002174 Styrene-butadiene Substances 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000010041 electrostatic spinning Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 229920005646 polycarboxylate Polymers 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/403—Manufacturing processes of separators, membranes or diaphragms
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
-
- 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
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
- H01M50/497—Ionic conductivity
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Composite Materials (AREA)
- Inorganic Chemistry (AREA)
- Cell Separators (AREA)
Abstract
The invention provides a diaphragm and a preparation method and application thereof, wherein the preparation method comprises the following steps: (1) mixing a dispersing agent, a binder, a polytriphenylamine additive and a solvent in one step to obtain a mixed solution; (2) mixing a thickening agent and the mixed solution obtained in the step (1) for two times, adjusting the pH value, and adding inorganic ceramic powder particles to obtain ceramic slurry; (3) and (3) coating the ceramic slurry obtained in the step (2) on the surface of a base film, and drying to obtain the diaphragm. According to the invention, the polytriphenylamine additive is applied to the diaphragm for the lithium ion battery, and on the basis of the traditional ceramic diaphragm, the wettability of the diaphragm to electrolyte is increased, the ion conduction capability of the diaphragm is improved, and the long-term cycle performance of the large-size battery is improved.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and relates to a diaphragm, and a preparation method and application thereof.
Background
The conventional base film and the alumina/boehmite coated ceramic diaphragm have the problems of poor infiltration and increased internal resistance of the large-size battery for vehicles because the PE/PP and the inorganic ceramic powder do not absorb electrolyte and the absorption rate and the retention rate of the diaphragm to the electrolyte are low.
CN113224458A discloses a preparation method of a high-safety long-life ceramic diaphragm, which comprises the following steps: 1) preparation of polymer solution: dissolving polymer powder and removing bubbles by ultrasonic waves to prepare a polymer solution with the mass concentration of 5-30%; 2) preparing a three-dimensional composite ceramic diaphragm: taking an organic diaphragm substrate with holes, coating a layer of ceramic slurry on the surface of the organic diaphragm substrate, and drying to form a ceramic coating layer to obtain a ceramic coated diaphragm; continuously coating a layer of heat-resistant layer on the surface of the ceramic coating diaphragm and the inner wall of the hole to obtain a three-dimensional composite ceramic diaphragm; 3) preparing a high-safety long-life ceramic diaphragm: preparing a polymer layer with the thickness of 5 nm-10 mu m on the surface of the three-dimensional composite ceramic diaphragm by adopting an electrostatic spinning technology; and then drying and hot-pressing to obtain the high-safety long-life ceramic diaphragm.
CN111244368A discloses a ceramic separator, in which a first aqueous slurry coating is coated on a separator substrate, and the surface of the first aqueous slurry coating is coated with a second aqueous slurry coating. The thickness of the second aqueous slurry coating is larger than that of the first aqueous slurry coating, and the compactness of the first aqueous slurry coating is larger than that of the second aqueous slurry coating.
The diaphragm of the scheme has the problem of poor wettability or poor ion conduction capability, so that the development of the diaphragm for the lithium ion battery, which has good wettability on electrolyte and simultaneously improves the ion conduction capability of the diaphragm, is necessary.
Disclosure of Invention
The invention aims to provide a diaphragm and a preparation method and application thereof, the invention applies polytriphenylamine additives to the diaphragm for a lithium ion battery, and on the basis of the traditional ceramic diaphragm, the wettability of the diaphragm to electrolyte is increased, the ion conduction capability of the diaphragm is improved, and the long-term cycle performance of a large-size battery is improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for preparing a separator, comprising the steps of:
(1) mixing a dispersing agent, a binder, a polytriphenylamine additive and a solvent in one step to obtain a mixed solution;
(2) mixing a thickening agent and the mixed solution obtained in the step (1) for two times, adjusting the pH value, and adding inorganic ceramic powder particles to obtain ceramic slurry;
(3) and (3) coating the ceramic slurry obtained in the step (2) on the surface of a base film, and drying to obtain the diaphragm.
According to the invention, the polytriphenylamine additive is added into the ceramic coating of the diaphragm, the polytriphenylamine compound has excellent charge transmission performance, the polytriphenylamine structural unit has a specific pi conjugated structure and good hole transmission capability, the polytriphenylamine has reversible redox reaction and electrochemical stability, and the polytriphenylamine is applied to the battery as a positive electrode material along with the embedding and the separation of anions in the electrolyte in the charging and discharging processes of the battery, and simultaneously has good adsorption and liquid retention performances on the electrolyte.
Preferably, the dispersant in step (1) comprises any one of or a combination of at least two of ammonium polycarboxylate salts, ammonium polyacrylate or polyvinyl alcohol.
Preferably, the mass fraction of the dispersant is 0.1-2% based on 100% of the mixed solution, such as: 0.1%, 0.5%, 0.8%, 1%, 1.5%, 2%, etc.
Preferably, the binder comprises any one of polyacrylic acid, polyacrylic acid modified polymer, styrene butadiene rubber or polydopamine or a combination of at least two of them.
Preferably, the mass fraction of the binder is 2-10% based on 100% of the mixed solution, for example: 2%, 4%, 6%, 8%, 10%, etc.
Preferably, the solvent comprises deionized water.
Preferably, the stirring time of the one-step mixing is 8-12 min, for example: 8min, 9min, 10min, 11min or 12min and the like.
Preferably, the polytriphenylamine additive in step (1) comprises any one of polytriphenylamine or polytriphenylamine derivatives or a combination of at least two of them.
Preferably, the morphology of the polytriphenylamine additive comprises any one of spherical, spheroidal or fibrous or a combination of at least two.
Preferably, the morphology of the polytriphenylamine additive is spherical and/or spheroidal, and the median particle diameter D50 of the polytriphenylamine additive is 100-2000 nm, such as: 100nm, 500nm, 800nm, 1000nm, 1500nm or 2000nm, etc.
Preferably, the appearance of the polytriphenylamine additive is fibrous, the diameter of the polytriphenylamine additive is 30-300 nm, for example: 30nm, 50nm, 100nm, 200nm, 300nm, etc.
Preferably, the mass fraction of the polytriphenylamine additive is 2-10% based on 100% of the mixed solution, for example: 2%, 4%, 6%, 8%, 10%, etc.
Preferably, the thickening agent in step (2) comprises any one of or a combination of at least two of sodium carboxymethyl cellulose, sodium carboxymethyl cellulose derivatives, sodium proteate and sodium polyacrylate.
Preferably, the mass ratio of the thickening agent to the mixed solution is 0.001-0.05: 1, such as: 0.001:1, 0.005:1, 0.01:1, 0.03:1 or 0.05, etc. 1.
Preferably, the pH is a weakly alkaline pH of 7.0 to 9.0.
Preferably, the stirring time of the two-step mixing is 20-40 min, for example: 20min, 25min, 30min, 35min or 40min and the like.
Preferably, the inorganic ceramic powder particles of step (2) include any one of alumina, boehmite, silica or magnesium hydroxide or a combination of at least two thereof.
Preferably, the inorganic ceramic powder particles have a median particle diameter D50 of 100 to 2000nm, for example: 100nm, 500nm, 800nm, 1000nm, 1500nm or 2000nm, etc.
Preferably, the solid content of the ceramic slurry is 20-60%, for example: 20%, 30%, 40%, 50%, 60%, etc., preferably 35 to 45%.
Preferably, the base film in step (3) is made of any one or a combination of at least two of PE, PP, PI, and aramid.
Preferably, the thickness of the base film is 4 to 20 μm, for example: 4 μm, 8 μm, 10 μm, 15 μm, 20 μm, or the like.
Preferably, the thickness of the single layer coated in the step (3) is 0.5-4 μm, for example: 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, or the like.
In a second aspect, the present invention provides a separator, wherein the separator is produced by the method according to the first aspect.
In a third aspect, the present invention provides a lithium ion battery comprising a separator according to the second aspect.
Compared with the prior art, the invention has the following beneficial effects:
(1) the invention increases the liquid absorption rate and the liquid retention rate of the electrolyte on the basis of the traditional ceramic diaphragm, improves the ion conduction capability and improves the long-term cycle performance of the large-size battery.
(2) Compared with the traditional diaphragm, the liquid absorption rate of the diaphragm is improved by 1.5-2 times, the liquid retention rate is improved by 10-20%, and the cycle performance is improved by 5-15%.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
The percentages in the examples and comparative examples are mass ratios unless otherwise specified.
Example 1
The embodiment provides a diaphragm, and a preparation method of the diaphragm comprises the following steps:
(1) mixing 1% of polycarboxylic acid ammonium salt with 86% of water, stirring for 10min for dispersing to obtain a dispersion liquid, sequentially adding 5% of PAA and 5% of spherical polytriphenylamine with the median particle size of 500nm into the dispersion liquid, and continuously stirring for 10min for uniform dispersion to obtain a mixed solution;
(2) adding 3% sodium carboxymethylcellulose, adjusting pH to 9, stirring at constant speed for 10min, adding 500nm boehmite D50, and stirring for 30min to obtain ceramic slurry with solid content of 40%;
(3) and (3) transferring the ceramic slurry obtained in the step (2) to the surface of a PE base film with the thickness of 10 microns through a micro gravure roller, coating the surface with the thickness of 2 microns, and drying to obtain the diaphragm.
Example 2
The embodiment provides a diaphragm, and a preparation method of the diaphragm comprises the following steps:
(1) mixing 1.5% of ammonium polyacrylate with 84% of water, stirring for 10min for dispersing to obtain a dispersion liquid, sequentially adding 5% of SBR and 6% of spheroidal polytriphenylamine with the median particle size of 600nm into the dispersion liquid, and continuously stirring for 10min for uniform dispersion to obtain a mixed solution;
(2) adding 3.5% sodium carboxymethylcellulose, adjusting pH to 9, stirring at constant speed for 10min, adding 600nm boehmite D50, and stirring for 30min to obtain ceramic slurry with solid content of 42%;
(3) and (3) transferring the ceramic slurry obtained in the step (2) to the surface of a PE base film with the thickness of 8 microns through a micro gravure roller, coating the surface with the thickness of 2.5 microns, and drying to obtain the diaphragm.
Example 3
The embodiment provides a diaphragm, and a preparation method of the diaphragm comprises the following steps:
(1) mixing 1% of polycarboxylic acid ammonium salt with 90% of water, stirring for 10min for dispersion to obtain a dispersion liquid, sequentially adding 5% of PAA and 1% of spherical polytriphenylamine with the median particle size of 500nm into the dispersion liquid, and continuously stirring for 10min for uniform dispersion to obtain a mixed solution;
(2) adding 3% sodium carboxymethylcellulose, adjusting pH to 9, stirring at constant speed for 10min, adding 500nm boehmite D50, and stirring for 30min to obtain ceramic slurry with solid content of 40%;
(3) and (3) transferring the ceramic slurry obtained in the step (2) to the surface of a PE base film with the thickness of 10 micrometers through a micro gravure roller, coating the PE base film with the thickness of 2 micrometers, and drying to obtain the diaphragm.
Example 4
The embodiment provides a diaphragm, and a preparation method of the diaphragm comprises the following steps:
(1) mixing 1% of polycarboxylic acid ammonium salt with 79% of water, stirring for 10min for dispersing to obtain a dispersion liquid, sequentially adding 5% of PAA and 12% of spherical polytriphenylamine with the median particle size of 500nm into the dispersion liquid, and continuously stirring for 10min for uniform dispersion to obtain a mixed solution;
(2) 3 percent sodium carboxymethylcellulose is added to regulate the pH value to 9 and is stirred at a constant speed for 10min, boehmite with D50 of 500nm is added to be stirred for 30min, and ceramic slurry with the solid content of 40 percent is obtained;
(3) and (3) transferring the ceramic slurry obtained in the step (2) to the surface of a PE base film with the thickness of 10 microns through a micro gravure roller, coating the surface with the thickness of 2 microns, and drying to obtain the diaphragm.
Example 5
The embodiment provides a diaphragm, and a preparation method of the diaphragm comprises the following steps:
(1) mixing 1% of polycarboxylic acid ammonium salt with 86% of water, stirring for 10min for dispersing to obtain a dispersion liquid, sequentially adding 5% of PAA and 5% of spherical polytriphenylamine with the median particle size of 500nm into the dispersion liquid, and continuously stirring for 10min for uniform dispersion to obtain a mixed solution;
(2) adding 3% sodium carboxymethylcellulose, adjusting pH to 9, stirring at constant speed for 10min, adding 500nm boehmite D50, and stirring for 30min to obtain ceramic slurry with solid content of 40%;
(3) and (3) transferring the ceramic slurry obtained in the step (2) to the surface of a PE base film with the thickness of 10 microns through a micro gravure roller, coating the surface with the thickness of 0.3 micron, and drying to obtain the diaphragm.
Example 6
The embodiment provides a diaphragm, and a preparation method of the diaphragm comprises the following steps:
(1) mixing 1% of polycarboxylic acid ammonium salt with 86% of water, stirring for 10min for dispersing to obtain a dispersion liquid, sequentially adding 5% of PAA and 5% of spherical polytriphenylamine with the median particle size of 500nm into the dispersion liquid, and continuously stirring for 10min for uniform dispersion to obtain a mixed solution;
(2) adding 3% sodium carboxymethylcellulose, adjusting pH to 9, stirring at constant speed for 10min, adding 500nm boehmite D50, and stirring for 30min to obtain ceramic slurry with solid content of 40%;
(3) and (3) transferring the ceramic slurry obtained in the step (2) to the surface of a PE base film with the thickness of 10 microns through a micro gravure roller, coating the surface with the thickness of 5 microns, and drying to obtain the diaphragm.
Comparative example 1
The embodiment provides a diaphragm, and a preparation method of the diaphragm comprises the following steps:
(1) mixing 1% of polycarboxylic acid ammonium salt with 91% of water, stirring for 10min for dispersing to obtain a dispersion liquid, adding 5% of PAA into the dispersion liquid, and continuously stirring for 10min for uniform dispersion to obtain a mixed solution;
(2) adding 3% sodium carboxymethylcellulose, adjusting pH to 9, stirring at constant speed for 10min, adding 500nm boehmite D50, and stirring for 30min to obtain ceramic slurry with solid content of 40%;
(3) and (3) transferring the ceramic slurry obtained in the step (2) to the surface of a PE base film with the thickness of 10 microns through a micro gravure roller, coating the surface with the thickness of 2 microns, and drying to obtain the diaphragm.
And (3) performance testing:
(1) method for testing liquid absorption rate
At the temperature of 23 +/-2 ℃ and the dew point of less than-45 ℃, 1% of inert coloring agent is dripped into the electrolyte for standby, a diaphragm sample with the length of more than 200mm and the width of actual width (< 100mm) or 100mm is taken, the diaphragm sample is cut into samples with the length of 150 x 15mm, two transparent glass plates are sampled and placed on a horizontal desktop, the two transparent glass plates are placed at the interval of 100mm in parallel, and double-faced adhesive tape marks are pasted on the inner sides of the positions to prevent the positions of the glass plates from changing. The two sides of the diaphragm are fixed on the glass plate by sticking the diaphragm with a tea-colored adhesive tape, and the diaphragm is required to have no folds and no couch. And (3) sucking 50ul of electrolyte by using a liquid-transferring gun, quickly dripping the electrolyte at a position 2-5mm above the diaphragm, and recording the diffusion time after dripping. After 60s, the MD diffusion length was measured with a ruler and photographed, and the diffusion length was used as an index for measuring the liquid absorption rate.
(2) Liquid retention rate testing method
The diaphragm and the same positive and negative electrode plates are wound into a bare cell, the weight of the bare cell is W0, the bare cell is immersed into a mixed solution of Ethylene Carbonate (EC) and Propylene Carbonate (PC) in a ratio of 1:1 at room temperature, the bare cell is kept stand for 2h, then the electrolyte on the surface is sucked by filter paper and weighed, the weight is W1, the bare cell is kept stand in the air for 12h at room temperature and weighed again, the mass is W2, and the liquid retention rate is (W2-W0)/(W1-W0).
(3) Battery cycle performance testing method
Under the environment of 45 ℃, the battery cell is charged and discharged at 0.5C/1C, the first circle of discharge capacity C0 and each circle of discharge capacity Cn are recorded, the discharge capacity retention rate is Cn × 100/C0, and the test results are shown in Table 1:
TABLE 1 test results
As can be seen from Table 1, in examples 1-6, the liquid absorption rate of the diaphragm disclosed by the invention can reach 52mm, the liquid retention rate can reach more than 93.1%, the capacity retention rate can reach more than 80.6% after 1000 cycles, the mass fraction of the polytriphenylamine additive is 2-10%, and the effect is optimal when the thickness of the coating layer is 2 μm.
The comparison between the embodiment 1 and the embodiments 3 to 4 shows that the mass concentration of the polytriphenylamine additive in the mixed solution affects the performance of the prepared diaphragm, the mass concentration of the polytriphenylamine additive is controlled to be 2-10%, the performance of the prepared diaphragm is good, if the mass concentration of the polytriphenylamine additive is too low, the wettability of the coating is improved slightly, so that the improvement effect on the cycle performance of the battery is not obvious, and if the mass concentration of the polytriphenylamine additive is too high, the wetting effect of other components in the coating on the electrolyte is weakened, and the cycle performance of the battery is also easily affected.
Compared with the examples 5 to 6, the coating thickness of the ceramic slurry influences the performance of the prepared diaphragm, the coating thickness of the ceramic slurry is controlled to be 0.5-4 mu m, the prepared diaphragm has excellent performance, if the coating thickness of the ceramic slurry is too small, the content of the polytrianiline is small, the infiltration effect cannot be effectively exerted, the coating thickness of the ceramic slurry is too large, the number of particles in the ceramic layer is too large, the electrolyte transmission path is lengthened, and the infiltration effect cannot be easily exerted.
Compared with the comparative example 1, the invention has the advantages that the polytriphenylamine additive is added into the ceramic coating of the diaphragm, the polytriphenylamine compound has excellent charge transmission performance, the polytriphenylamine structural unit has a specific pi conjugated structure and good hole transmission capacity, the polytriphenylamine has reversible redox reaction and electrochemical stability, the insertion and the separation of anions in the electrolyte are accompanied in the charging and discharging process of the battery, the polytriphenylamine is used as the anode material to be applied to the battery, and meanwhile, the polytriphenylamine additive has good adsorption and liquid retention performances on the electrolyte.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (10)
1. A method for producing a separator, comprising the steps of:
(1) mixing a dispersing agent, a binder, a polytriphenylamine additive and a solvent in one step to obtain a mixed solution;
(2) mixing a thickening agent and the mixed solution obtained in the step (1) for two times, adjusting the pH value, and adding inorganic ceramic powder particles to obtain ceramic slurry;
(3) and (3) coating the ceramic slurry obtained in the step (2) on the surface of a base film, and drying to obtain the diaphragm.
2. The method according to claim 1, wherein the dispersant in step (1) comprises any one or a combination of at least two of polycarboxylic acid ammonium salt, polypropylene ammonium or polyvinyl alcohol;
preferably, the mass fraction of the dispersing agent is 0.1-2% based on 100% of the mixed solution;
preferably, the binder comprises any one or a combination of at least two of polyacrylic acid, polyacrylic acid modified polymer, styrene butadiene rubber or polydopamine;
preferably, the mass fraction of the binder is 2-10% based on 100% of the mixed solution;
preferably, the solvent comprises deionized water;
preferably, the stirring time of the one-step mixing is 8-12 min.
3. The method of claim 1 or 2, wherein the polytriphenylamine additive of step (1) comprises any one of polytriphenylamine or a polytriphenylamine derivative or a combination of at least two of them;
preferably, the morphology of the polytriphenylamine additive comprises any one of spherical, spheroidal or fibrous or a combination of at least two.
4. The method of any one of claims 1-3, wherein the polytriphenylamine additive of step (1) is spherical and/or spheroidal in morphology, and the polytriphenylamine additive has a median particle diameter D50 of 100 to 2000 nm;
preferably, the appearance of the polytriphenylamine additive is fibrous, and the diameter of the polytriphenylamine additive is 30-300 nm;
preferably, the mass fraction of the polytriphenylamine additive is 2-10% based on 100% of the mixed solution.
5. The method according to any one of claims 1 to 4, wherein the thickener in step (2) comprises any one or a combination of at least two of sodium carboxymethylcellulose, a derivative of sodium carboxymethylcellulose, sodium proteocapsus, or sodium polyacrylate;
preferably, the mass ratio of the thickening agent to the mixed solution is 0.001-0.05: 1;
preferably, the pH is weakly alkaline and the pH value is 7.0-9.0;
preferably, the stirring time of the two-step mixing is 20-40 min.
6. The method according to any one of claims 1 to 5, wherein the inorganic ceramic powder particles of step (2) comprise any one of alumina, boehmite, silica or magnesium hydroxide or a combination of at least two thereof;
preferably, the median particle diameter D50 of the inorganic ceramic powder particles is 100-2000 nm;
preferably, the solid content of the ceramic slurry is 20-60%, and preferably 35-45%.
7. The method according to any one of claims 1 to 6, wherein the base film of step (3) is made of any one or a combination of at least two of PE, PP, PI or aramid;
preferably, the thickness of the base film is 4 to 20 μm.
8. The method of any one of claims 1-7, wherein the monolayer applied in step (3) is 0.5 to 4 μm thick.
9. A separator, wherein the separator is produced by the method of any one of claims 1 to 8.
10. A lithium ion battery comprising the separator of claim 9.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115101891A (en) * | 2022-07-19 | 2022-09-23 | 中材锂膜有限公司 | Preparation method of lithium ion battery diaphragm |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113611983A (en) * | 2021-08-02 | 2021-11-05 | 湖南烁普新材料有限公司 | Composite diaphragm slurry, preparation method thereof and battery diaphragm |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113611983A (en) * | 2021-08-02 | 2021-11-05 | 湖南烁普新材料有限公司 | Composite diaphragm slurry, preparation method thereof and battery diaphragm |
Non-Patent Citations (1)
| Title |
|---|
| J.K. FENG等: ""Polytriphenylamine used as an electroactive separator material for overcharge protection of rechargeable lithium battery"", 《JOURNAL OF POWER SOURCES》, pages 545 - 549 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115101891A (en) * | 2022-07-19 | 2022-09-23 | 中材锂膜有限公司 | Preparation method of lithium ion battery diaphragm |
| CN115101891B (en) * | 2022-07-19 | 2024-03-05 | 中材锂膜有限公司 | Preparation method of lithium ion battery diaphragm |
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