CN108586757B - Adhesive for battery diaphragm coating and preparation method thereof - Google Patents

Adhesive for battery diaphragm coating and preparation method thereof Download PDF

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CN108586757B
CN108586757B CN201810368728.8A CN201810368728A CN108586757B CN 108586757 B CN108586757 B CN 108586757B CN 201810368728 A CN201810368728 A CN 201810368728A CN 108586757 B CN108586757 B CN 108586757B
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adhesive
coating
fluorine
containing polyolefin
battery
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CN108586757A (en
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汪圣龙
蒋中林
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Dongguan Mofang New Energy Technology Co ltd
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    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G81/00Macromolecular compounds obtained by interreacting polymers in the absence of monomers, e.g. block polymers
    • C08G81/02Macromolecular compounds obtained by interreacting polymers in the absence of monomers, e.g. block polymers at least one of the polymers being obtained by reactions involving only carbon-to-carbon unsaturated bonds
    • C08G81/021Block or graft polymers containing only sequences of polymers of C08C or C08F
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04Coating
    • C08J7/0427Coating with only one layer of a composition containing a polymer binder
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/12Chemical modification
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D101/00Coating compositions based on cellulose, modified cellulose, or cellulose derivatives
    • C09D101/08Cellulose derivatives
    • C09D101/26Cellulose ethers
    • C09D101/28Alkyl ethers
    • C09D101/286Alkyl ethers substituted with acid radicals
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40Additives
    • C09D7/60Additives non-macromolecular
    • C09D7/61Additives non-macromolecular inorganic
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40Additives
    • C09D7/65Additives macromolecular
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40Additives
    • C09D7/66Additives characterised by particle size
    • C09D7/67Particle size smaller than 100 nm
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/10Homopolymers or copolymers of propene
    • C08J2323/12Polypropene
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2401/00Characterised by the use of cellulose, modified cellulose or cellulose derivatives
    • C08J2401/08Cellulose derivatives
    • C08J2401/26Cellulose ethers
    • C08J2401/28Alkyl ethers
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2487/00Characterised by the use of unspecified macromolecular compounds, obtained otherwise than by polymerisation reactions only involving unsaturated carbon-to-carbon bonds
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00Use of inorganic substances as compounding ingredients
    • C08K3/18Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20Oxides; Hydroxides
    • C08K3/22Oxides; Hydroxides of metals
    • C08K2003/2227Oxides; Hydroxides of metals of aluminium
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00Specific properties of additives
    • C08K2201/011Nanostructured additives
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

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  • Chemical & Material Sciences (AREA)
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  • Wood Science & Technology (AREA)
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  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Health & Medical Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Nanotechnology (AREA)
  • Electrochemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Cell Separators (AREA)
  • Adhesives Or Adhesive Processes (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention relates to an adhesive for a battery diaphragm coating and a preparation method thereof, wherein the adhesive comprises fluorine-containing polyolefin/hydrophilic macromolecule dendritic graft polymer; the preparation method comprises the step of grafting a hydrophilic high molecular polymer onto fluorine-containing polyolefin under the action of ultraviolet rays by using a photosensitizer to form the dendritic polymer with a large number of hydrophilic groups. The adhesive is used for the lithium battery ceramic diaphragm, can effectively inhibit the shedding of ceramic powder, and effectively improve the liquid absorption/retention capacity of the diaphragm; after the diaphragm is assembled into the battery, the battery has the advantages of superior cycle performance, high ionic conductivity, excellent rate performance and the like.

Description

Adhesive for battery diaphragm coating and preparation method thereof
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to an adhesive for a battery diaphragm coating and a preparation method thereof.
Background
The diaphragm is an important component of the lithium ion battery, and the performance of the diaphragm determines the interface structure, internal resistance and the like of the battery and directly influences the capacity, cycle performance, safety and the like of the battery. The ceramic diaphragm is a novel high-safety diaphragm material developed on the conventional polyolefin diaphragm, and the main preparation method of the ceramic diaphragm is to use inorganic powder (such as Al)2O3、SiO2、TiO2Etc.), an adhesive, etc. are dispersed in a solvent, and a ceramic coating is formed on the surface of the polyolefin separator base material by a casting method or an immersion method. The thermal shrinkage performance, the liquid absorption rate and the wettability of the ceramic diaphragm and the ionic conductivity, the capacity retention and the rate capability of the lithium battery applying the ceramic diaphragm are affected by inorganic powder, adhesive and the manufacturing processThe influence of (c).
At present, the main research directions on ceramic diaphragm coatings include inorganic powder and a manufacturing process thereof, and modification and synthesis of adhesives, for example, patent CN 106186008A discloses boehmite for lithium battery diaphragm coatings and a hydrothermal preparation method thereof, and patent CN 103560219a discloses a preparation method of ceramic diaphragms using polydopamine as adhesives.
The traditional adhesive, such as polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene, has good mechanical properties, chemical resistance and adhesiveness, but has a space for improving the wettability of a diaphragm and the electrochemical performance of a battery due to the hydrophobicity of the traditional adhesive; for example, polymethyl methacrylate adhesives have a certain liquid absorption property, but have poor adhesion performance, and easily cause separation of ceramic powder of a separator, thereby causing a safety problem of a battery. Therefore, modification treatment of the conventional adhesive is inevitably required.
Disclosure of Invention
The invention aims to: aiming at the problems of poor wettability of the ceramic diaphragm, easy falling of ceramic powder and the like caused by poor hydrophilicity and weak bonding capability of the existing battery ceramic diaphragm adhesive, the adhesive for the battery diaphragm coating, which has high hydrophilicity, high adhesion and high electrochemical stability, and the preparation process thereof are provided.
In order to achieve the purpose, the invention adopts the following technical scheme:
the adhesive for coating the battery separator comprises fluorine-containing polyolefin/hydrophilic macromolecule dendritic graft polymer. The invention uses photosensitizer to graft hydrophilic high molecular polymer on fluorine-containing polyolefin under the action of ultraviolet ray, so as to form dendritic polymer with a large amount of hydrophilic groups.
The preparation method of the adhesive for the battery diaphragm coating comprises the following steps:
step (1): preparing a mixed solution of fluorine-containing polyolefin, hydrophilic polymer and photosensitizer: adding a photosensitizer, fluorine-containing polyolefin and hydrophilic polymer into a solvent according to the weight ratio of 0.3-0.5:50-80:80-100, and stirring for 4-6 hours to prepare a mixed solution with the solid content of 10-20%;
step (2): preparing a fluorine-containing polyolefin/hydrophilic polymer graft polymer solution: placing the mixed solution prepared in the step (1) into an ultraviolet reactor, irradiating for 10-30 min in an inert gas protective atmosphere at an illumination distance of 20-40 cm to prepare a fluorine-containing polyolefin/hydrophilic polymer graft polymer solution;
and (3): and (3) carrying out spray drying on the fluorine-containing polyolefin/hydrophilic high polymer graft polymer solution prepared in the step (2) to obtain the adhesive for the battery diaphragm coating.
Preferably, in step (1), the photosensitizer is at least one of benzophenone and diphenylethanone.
Preferably, in the step (1), the fluorinated polyolefin is at least one of polyvinylidene fluoride having a weight average molecular weight of 150000 to 250000 and polyvinylidene fluoride-hexafluoropropylene copolymer having a weight average molecular weight of 200000 to 300000.
Preferably, in the step (1), the hydrophilic polymer is at least one of polyacrylic acid having a weight average molecular weight of 100000-150000 and polyacrylonitrile having a weight average molecular weight of 80000-150000.
Preferably, in the step (1), the solvent is at least one of N, N-Dimethylformamide (DMF), N-Dimethylacetamide (DMAC), and 1-methyl-2-pyrrolidone (NMP).
Preferably, in the step (2), the inert gas protective atmosphere is a helium atmosphere, an argon atmosphere or a nitrogen atmosphere.
Compared with the prior art, the photosensitizer of aryl ketone mixture such as benzophenone, diphenylethanone, xanthone and the like can capture hydrogen of hydrogen donor after absorbing ultraviolet light to form two free radicals, so that different hydrogen donors react to form a graft polymer. For hydrophilic high molecular polymers polyacrylic acid and polyacrylonitrile with carbon-hydrogen bonds, under the action of a photosensitizer and ultraviolet light, the hydrophilic high molecular polymers polyacrylic acid and polyacrylonitrile can be grafted with fluorine-containing polyolefin to form fluorine-containing polyolefin/hydrophilic high molecular graft polymers, the polymer particles have a dendritic structure, hydrophilic high molecular chains containing a large number of polar groups are arranged on the periphery of the polymer particles, the polymer particles are just like tentacles of octopus, multi-point bonding can be formed, the excellent chemical resistance and the bonding property of the fluorine-containing polyolefin are achieved, and the lyophilic property of the bonding agent is improved. The adhesive is used for the lithium battery ceramic diaphragm, can effectively inhibit the shedding of ceramic powder, and effectively improve the liquid absorption/retention capacity of the diaphragm; after the diaphragm is assembled into the battery, the battery has the advantages of superior cycle performance, high ionic conductivity, excellent rate performance and the like.
Detailed Description
In order to make the technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Adding benzophenone, polyvinylidene fluoride and polyacrylic acid into N, N-Dimethylformamide (DMF) solvent according to the weight ratio of 0.5:80:100, and continuously stirring for 4 hours to prepare a mixed solution with the solid content of 10%; placing the prepared mixed solution into an ultraviolet reactor, irradiating for 30min in a nitrogen protective atmosphere at an irradiation distance of 40cm to prepare a fluorine-containing polyolefin/hydrophilic polymer graft polymer solution; and spray drying to obtain the adhesive for the battery diaphragm coating.
Adding the adhesive powder, the aluminum oxide nano particles and the carboxymethyl cellulose into the aqueous solution according to the weight ratio of 5:1:90 to prepare a mixed solution with the solid content of 50%, and mixing for 1h at the rotating speed of 20000 to obtain the coating slurry. Coating the slurry on the surface of a polypropylene diaphragm by adopting a blade coating mode, drying at 70 ℃ to obtain a lithium battery ceramic diaphragm coating with the thickness of 5 mu m, and fully soaking LiPF6Electrolyte with surface lithium ion conductivity of 3.7 × 10 measured by electrochemical workstation-3Scm-1The coating adhesion is 49Nm-1(ii) a Assembled into LiFePO4a/C lithium battery. The electrochemical workstation is adopted to test the cycle performance, and after the electrochemical workstation is cycled for 400 circles, the cycle performance is still maintainedAn initial discharge capacity of 94% was maintained. As a comparison sample, polyvinylidene fluoride, carboxymethyl cellulose and aluminum oxide nano particles are prepared into slurry and a coating according to the same proportion, and the lithium ion conductivity of the surface of the slurry and the coating is measured to be 5.7 multiplied by 10-4Scm-1The coating adhesion is 15Nm-1After 400 cycles, the capacity retention was only 79%.
Example 2
Adding diphenylethanone, polyvinylidene fluoride and polyacrylonitrile into an N, N-Dimethylacetamide (DMAC) solvent according to the weight ratio of 0.4:70:100, and continuously stirring for 5 hours to prepare a mixed solution with the solid content of 15%; placing the prepared mixed solution into an ultraviolet reactor, irradiating for 20min in an argon protective atmosphere at an irradiation distance of 20cm to prepare a fluorine-containing polyolefin/hydrophilic polymer graft polymer solution; and spray drying to obtain the adhesive for the battery diaphragm coating.
Adding the adhesive powder, the aluminum oxide nanoparticles and the hydroxypropyl methyl cellulose into the aqueous solution according to the weight ratio of 5:2:90 to prepare a mixed solution with the solid content of 45%, and mixing for 1h at the rotating speed of 15000 to obtain the slurry for the coating. Coating the slurry on the surface of a polypropylene diaphragm by adopting a blade coating mode, drying at 60 ℃ to obtain a lithium battery ceramic diaphragm coating with the thickness of 5 mu m, and fully soaking LiPF6Electrolyte with surface lithium ion conductivity of 3.5 × 10 measured by electrochemical workstation-3Scm-1The coating adhesion is 43Nm-1(ii) a Assembled into LiFePO4a/C lithium battery. The electrochemical workstation was used to test the cycling performance, and after 400 cycles, 92% of the initial discharge capacity was still maintained. As a comparison sample, polymethyl methacrylate, hydroxypropyl methyl cellulose and aluminum oxide nanoparticles are prepared into slurry and a coating according to the same proportion, and the lithium ion conductivity of the surface of the slurry and the coating is measured to be 5.7 multiplied by 10- 4Scm-1The coating adhesion is 13Nm-1After 400 cycles, the capacity retention was only 80%.
Example 3
Adding benzophenone, polyvinylidene fluoride-hexafluoropropylene copolymer and polyacrylonitrile into a 1-methyl-2-pyrrolidone (NMP) solvent according to the weight ratio of 0.3:50:90, and continuously stirring for 4 hours to prepare a mixed solution with the solid content of 17%; placing the prepared mixed solution into an ultraviolet reactor, irradiating for 20min in a helium protective atmosphere at an irradiation distance of 30cm to prepare a fluorine-containing polyolefin/hydrophilic polymer graft polymer solution; and spray drying to obtain the adhesive for the battery diaphragm coating.
Adding the adhesive powder, the titanium dioxide nano particles and the hydroxypropyl methyl cellulose into the aqueous solution according to the weight ratio of 6:2:90 to prepare a mixed solution with the solid content of 45%, and mixing for 2 hours at the rotating speed of 20000 to obtain the slurry for the coating. Coating the slurry on the surface of a polypropylene diaphragm by adopting a blade coating mode, drying at 80 ℃ to obtain a lithium battery ceramic diaphragm coating with the thickness of 5 mu m, and fully infiltrating LiPF6Electrolyte with surface lithium ion conductivity of 3.2 × 10 measured by electrochemical workstation-3Scm-1The coating adhesion is 57Nm-1(ii) a Assembled into LiFePO4a/C lithium battery. Testing the cycle performance by using an electrochemical workstation, and after circulating for 400 circles, still keeping 91% of the initial discharge capacity; as a comparison sample, polyvinylidene fluoride-hexafluoropropylene copolymer, hydroxypropyl methyl cellulose and titanium dioxide nanoparticles are prepared into slurry and a coating according to the same proportion, and the lithium ion conductivity of the surface of the slurry and the coating is measured to be 4.1 multiplied by 10-4Scm-1The coating adhesion is 18Nm-1After 400 cycles, the capacity retention was only 78%.
Example 4
Adding diphenylethanone, polyvinylidene fluoride-hexafluoropropylene copolymer and polyacrylic acid into N, N-Dimethylformamide (DMF) solvent according to the weight ratio of 0.4:70:90, and continuously stirring for 5 hours to prepare a mixed solution with the solid content of 16%; placing the prepared mixed solution into an ultraviolet reactor, irradiating for 35min in a nitrogen protective atmosphere at an irradiation distance of 25cm to prepare a fluorine-containing polyolefin/hydrophilic polymer graft polymer solution; and spray drying to obtain the adhesive for the battery diaphragm coating.
Adding adhesive powder, titanium dioxide nanoparticles and hydroxypropyl methyl cellulose into the aqueous solution according to the weight ratio of 5:3:90 to prepare a mixed solution with the solid content of 46%, and mixing at the rotating speed of 15000And mixing for 2.5h to obtain the coating slurry. Coating the slurry on the surface of a polypropylene diaphragm by adopting a blade coating mode, drying at 70 ℃ to obtain a lithium battery ceramic diaphragm coating with the thickness of 5 mu m, and fully soaking LiPF6Electrolyte with surface lithium ion conductivity of 3.6 × 10 measured by electrochemical workstation-3Scm-1Coating adhesion 47Nm-1(ii) a Assembled into LiFePO4a/C lithium battery. Testing the cycle performance by using an electrochemical workstation, and still maintaining 92% of initial discharge capacity after 400 cycles of cycle; as a comparison sample, polymethyl methacrylate, hydroxypropyl methylcellulose and titanium dioxide nano particles are prepared into slurry and a coating according to the same proportion, and the lithium ion conductivity of the surface of the slurry and the coating is measured to be 5.1 multiplied by 10-4Scm-1The coating adhesion is 20Nm-1After 400 cycles, the capacity retention was only 78%.
Variations and modifications to the above-described embodiments may also occur to those skilled in the art, which fall within the scope of the invention as disclosed and taught herein. Therefore, the present invention is not limited to the above-mentioned embodiments, and any obvious improvement, replacement or modification made by those skilled in the art based on the present invention is within the protection scope of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (5)

1. An adhesive for coating a battery separator, characterized in that: the adhesive comprises fluorine-containing polyolefin/hydrophilic macromolecule dendritic graft polymer; the fluorine-containing polyolefin is at least one of polyvinylidene fluoride with the weight-average molecular weight of 150000-250000 and polyvinylidene fluoride-hexafluoropropylene copolymer with the weight-average molecular weight of 200000-300000; the hydrophilic polymer is at least one of polyacrylic acid with the weight-average molecular weight of 100000-150000 and polyacrylonitrile with the weight-average molecular weight of 80000-150000.
2. The method for preparing the adhesive for coating the battery separator according to claim 1, comprising the steps of:
step (1): preparing a mixed solution of fluorine-containing polyolefin, hydrophilic polymer and photosensitizer: adding a photosensitizer, fluorine-containing polyolefin and hydrophilic polymer into a solvent according to the weight ratio of 0.3-0.5:50-80:80-100, and stirring for 4-6 hours to prepare a mixed solution with the solid content of 10-20%;
step (2): preparing a fluorine-containing polyolefin/hydrophilic polymer graft polymer solution: placing the mixed solution prepared in the step (1) into an ultraviolet reactor, irradiating for 10-30 min in an inert gas protective atmosphere at an illumination distance of 20-40 cm to prepare a fluorine-containing polyolefin/hydrophilic polymer graft polymer solution;
and (3): and (3) carrying out spray drying on the fluorine-containing polyolefin/hydrophilic high polymer graft polymer solution prepared in the step (2) to obtain the adhesive for the battery diaphragm coating.
3. The method for preparing the adhesive for coating the battery separator according to claim 2, wherein: in the step (1), the photosensitizer is at least one of benzophenone, diphenylethanone and xanthone.
4. The method for preparing the adhesive for coating the battery separator according to claim 2, wherein: in the step (1), the solvent is at least one of N, N-Dimethylformamide (DMF), N-Dimethylacetamide (DMAC) and 1-methyl-2-pyrrolidone (NMP).
5. The method for preparing the adhesive for coating the battery separator according to claim 2, wherein: in the step (2), the inert gas protective atmosphere is helium atmosphere, argon atmosphere or nitrogen atmosphere.
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CN111725494B (en) * 2020-06-30 2021-11-09 蜂巢能源科技有限公司 Lithium material, lithium-containing material dispersion liquid, electrode material, and preparation methods and applications thereof
CN113555645B (en) * 2021-06-01 2023-09-05 惠州锂威新能源科技有限公司 Modified diaphragm, lithium ion battery and power utilization device
CN115477876A (en) * 2021-06-16 2022-12-16 深圳市星源材质科技股份有限公司 Coating slurry, coating diaphragm and preparation method of coating diaphragm

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