CN104064708A - Membrane for lithium ion secondary battery, preparation method of membrane and battery containing membrane - Google Patents
Membrane for lithium ion secondary battery, preparation method of membrane and battery containing membrane Download PDFInfo
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- CN104064708A CN104064708A CN201410251947.XA CN201410251947A CN104064708A CN 104064708 A CN104064708 A CN 104064708A CN 201410251947 A CN201410251947 A CN 201410251947A CN 104064708 A CN104064708 A CN 104064708A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/403—Manufacturing processes of separators, membranes or diaphragms
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a membrane for a lithium ion secondary battery. The membrane comprises an isolating membrane and a plurality of porous insulating layers, wherein the porous insulating layers are arranged on at least one surface of the isolating membrane and contain inorganic particles and binding agents, and the average particle sizes of the inorganic particles of each porous insulating layer are gradually increased from the surface of the isolating membrane to the direction of a pole piece. The invention further discloses a preparation method of the membrane. The preparation method comprises the following steps: firstly, mixing and dispersing the inorganic particles and the binding agents in a solvent to obtain a mixture A, preparing multiple mixtures A by adopting the inorganic particles of which the average particle diameters are changed in a gradient manner, coating the surface of the isolating membrane with the multiple mixtures A according to the sequence of the average particle diameters of the contained inorganic particles from small to large, and drying to obtain the membrane. The invention further discloses a lithium ion secondary battery containing the membrane. The membrane has the advantages of good thermostability, low thermal shrinkage, excellent safety performance and good electrochemical performance, the preparation method of the membrane has the advantages of simplicity and convenience in operation, and the lithium ion secondary battery containing the membrane has excellent safety performance and good electrochemical performance.
Description
Technical field
The present invention relates to technical field of lithium ion secondary, relate in particular to a kind of Separator for Lithium-ion battery, its preparation method and the battery containing this barrier film.
Background technology
The features such as lithium rechargeable battery is because energy density is large, and operating voltage is high, and quality is light, at consumption electronic product, as mobile phone, notebook computer, panel computer, bluetooth earphone, MP3, the fields such as digital camera are widely used.Increasingly serious along with environmental pollution and problem of energy crisis, lithium rechargeable battery is also more and more universal in the use in the field such as electrokinetic cell and stationary electric power plant, but the safety issue of lithium rechargeable battery is the focus that people pay close attention to always.
The barrier film of lithium rechargeable battery, as the isolation of both positive and negative polarity, is clipped between both positive and negative polarity, and Main Function is to prevent that both positive and negative polarity from directly contacting and being short-circuited.Barrier film is mainly by polyethylene at present, the porous media of the TPO compositions such as polypropylene, polyalkene diaphragm has 200 DEG C of following fusing points, when lithium rechargeable battery is because inside or external factor cause being short-circuited heating and temperature while raising, very easily there is thermal contraction and cause the short circuit that both positive and negative polarity is larger to produce in barrier film, causes the thermal runaway of battery to cause accident on fire.
In order to address the above problem, industry applies at membrane surface the porous dielectric layer that one deck is made up of inorganic particulate, because inorganic particulate has good thermal stability, this porous dielectric layer can stop both positive and negative polarity directly to contact as supporting layer in the time of barrier film thermal contraction, thereby avoids occurring problem on fire.As win the patent CN101301586B of Chuan Degusai Co., Ltd, the patent CN100438140C of Samsung SDI Co., Ltd, the patent CN101326658A of LG chemistry pillar commercial firm, the patent CN102244223A of Dongguan New Energy Technology Co etc.
The pore size of barrier film is mainly in 0.1 μ m, and the pore size after both positive and negative polarity pole piece is colded pressing, mainly at 1 ~ 10 μ m, exists the abrupt change in an aperture between barrier film and both positive and negative polarity pole piece, and on this interface, lithium ion transport resistance can increase.The porous dielectric layer applying at membrane surface is according to the granular size difference of inorganic particulate and the difference of formula, general pore size is at 0.01 ~ 5 μ m, this porous dielectric layer can be from barrier film to forming preliminary gradient aperture both positive and negative polarity pole piece, can reduce the transport resistance of the lithium ion of part.Win the patent CN101301586B of Chuan Degusai Co., Ltd, the patent CN100438140C of Samsung SDI Co., Ltd, the porous dielectric layer of the patent CN102244223A of Dongguan New Energy Technology Co is all equal one deck, pore size scope is fixed, in the patent CN101326658A of LG chemistry pillar commercial firm, porous dielectric layer is inhomogeneous composition from barrier film to pole piece, use same binding agent and inorganic particulate, just the ratio of binding agent and inorganic particulate changes, can not form the graded in aperture, at barrier film interface or both positive and negative polarity pole piece interface still can there is the situation of aperture abrupt change, the transport resistance of lithium ion is still larger, the chemical property of lithium battery secondary cell still can be influenced.
Summary of the invention
One of task of the present invention is to provide a kind of good thermal stability, have ultralow thermal contraction has the Separator for Lithium-ion battery of excellent security performance and good chemical property, two of task of the present invention be to provide a kind of easy and simple to handle, flow process is simply prepared good thermal stability, have ultralow thermal contraction has a method of the Separator for Lithium-ion battery of excellent security performance and good chemical property, three of task of the present invention is to provide a kind of lithium rechargeable battery with excellent security performance and good chemical property.
The present invention realizes by following technical proposals:
A kind of Separator for Lithium-ion battery, it is characterized in that: comprise barrier film and at least one the lip-deep multi-layer porous insulating barrier that is arranged on barrier film for separating two kinds of pole pieces of battery, porous dielectric layer comprises inorganic particulate and binding agent, the mean particle size of the inorganic particulate of every layer of porous dielectric layer becomes gradually large on barrier film surface on the direction of pole piece, and makes the pore size of multi-layer porous insulating barrier form graded from small to large from barrier film to pole piece direction; The number of plies that is positioned at the porous dielectric layer of the same side of barrier film is n, n >=2, be insulating barrier 1 apart from the nearest one deck porous dielectric layer in barrier film surface, be insulating barrier n apart from barrier film surface one deck porous dielectric layer farthest, between insulating barrier 1 and insulating barrier n, be disposed with insulating barrier 2, insulating barrier 3 ... with insulating barrier n-1; Wherein inorganic particulate has no particular limits, and only otherwise oxidation can occur in lithium rechargeable battery or reduce, has good electronic isolation simultaneously.
The average grain diameter of the described inorganic particulate that described insulating barrier 1 is selected is 0.05 ~ 0.2 μ m, and particle size distribution is 0.01 ~ 2 μ m; Described insulating barrier 2 is 0.2 ~ 8 μ m to the average grain diameter of the inorganic particulate that described insulating barrier n-1 selects, and particle size distribution is 0.08 ~ 10 μ m; The average grain diameter of the inorganic particulate that insulating barrier n selects is 1 ~ 10 μ m, and particle size distribution is 0.1 ~ 12 μ m; The number of plies n of described porous dielectric layer is 2 ~ 10, and the thickness of every layer of porous dielectric layer is 0.4 ~ 10 μ m, and the thickness of preferred every layer of porous dielectric layer is 0.5 ~ 10 μ m.
The average grain diameter of the described inorganic particulate that described insulating barrier 1 is selected is preferably 0.08 ~ 0.15 μ m, and particle size distribution is 0.02 ~ 1.8 μ m; The average grain diameter of the inorganic particulate that described insulating barrier n selects is preferably 0.3 ~ 8 μ m, and particle size range is 0.1 ~ 10 μ m, and average grain diameter is 0.3 ~ 6 μ m more preferably; The thickness of every layer of described porous dielectric layer is 1 ~ 6 μ m.
The material of described barrier film is polyethylene, polypropylene, polyimides or nonwoven fabrics.
Described inorganic particulate be in calcium oxide, zinc oxide, magnesium oxide, titanium dioxide, silicon dioxide, zirconium dioxide, tin ash, ceria, alundum (Al2O3), calcium carbonate and barium titanate any one or multiple.
Described binding agent be in styrene-butadiene polymer, Kynoar, Kynoar-hexafluoropropylene, polyacrylic acid, polymethylacrylic acid, polyacrylate, polymethyl methacrylate, polyacrylonitrile, sodium carboxymethylcellulose, butadiene-acrylonitrile polymer, polyvinylpyrrolidone and polyacrylic acid-styrene any one or multiple.
The mass ratio of described inorganic particulate and binding agent is 50:50 ~ 99.9:0.1, as 50:50,60:40,70:30,80:20,90:10,99.9:0.5,99.9:0.1 etc.; Described porous dielectric layer is arranged on described barrier film by the mode applying.
A preparation method for Separator for Lithium-ion battery, is characterized in that: its step comprises as follows:
A) dispersed with stirring of described inorganic particulate and described binding agent: binding agent is dissolved in solvent to form polymer solution, then adds inorganic particulate and mix, obtain mixture A, the concentration of mixture A is 10 ~ 70wt%, more preferably 20 ~ 70wt%; Being not particularly limited of operable solvent, can dissolve binding agent and dispersed inorganic particulate and can easily remove in coating is dry;
B) on the surface of described barrier film, apply described multi-layer porous insulating barrier, make Separator for Lithium-ion battery: first the mixture A of the mean particle size minimum of the inorganic particulate comprising is coated to barrier film surface, after dry, form described insulating barrier 1, again the mean particle size of the inorganic particulate comprising is become gradually to large mixture A and be coated to successively barrier film surface, form described insulating barrier 2, insulating barrier 3 ... with insulating barrier n, insulating barrier 1, insulating barrier 2, insulating barrier 3 ... form multi-layer porous insulating barrier with insulating barrier n, after every coating one deck mixture A, need to be first dried processing and apply again lower one deck mixture A, after applying n layer mixture A, be also dried processing.
Preferred described solvent is one or more in oxolane, methylethylketone, dimethyl formamide, dimethylacetylamide, tetramethylurea, tetramethyl phosphate, acetone, carrene, chloroform, dimethylformamide, 1-METHYLPYRROLIDONE, cyclohexane, water, alcohol; The concentration of described mixture A is 20 ~ 60wt%; The mode that described step b) is coated in mixture A barrier film surface be dip-coating, die head painting, roller coat, scraper shift be coated with and intaglio plate in being coated with any one or multiple.
Lithium rechargeable battery, it comprises positive plate, negative plate, electrolyte and the barrier film between positive plate and negative plate, it is characterized in that: described barrier film is described a kind of Separator for Lithium-ion battery.
The present invention has the following advantages: described Separator for Lithium-ion battery comprises porous dielectric layer, inorganic particulate in porous dielectric layer has good thermal stability, suppress the contraction of barrier film under high-temperature condition, improve its thermal stability, on barrier film, be provided with porous dielectric layer simultaneously, form the gradient of pore size to each layer of porous dielectric layer between pole piece (positive plate or negative plate) on barrier film surface, the inorganic particulate self-assembling formation differing by selecting mean particle size in the aperture of this graded, this gradient aperture can significantly reduce lithium ion barrier film with just, the interface transport resistance of negative plate, improve the chemical property of the lithium rechargeable battery that comprises Separator for Lithium-ion battery of the present invention, the method of simultaneously preparing Separator for Lithium-ion battery is easy, easy operating.
Brief description of the drawings
Fig. 1 is the structural representation of Separator for Lithium-ion battery of the present invention;
Wherein: g1: barrier film, g2: multi-layer porous insulating barrier, g201: insulating barrier 1, g202: insulating barrier 2, g203, insulating barrier 3, g204: hole.
Embodiment
In order to make, technical solution of the present invention and effect are more clear to be understood, below in conjunction with embodiment, the present invention is done to further detailed elaboration, but embodiments of the present invention is not limited to this.
comparative example 1
The preparation of positive plate:
By cobalt acid lithium, conductive carbon, binding agent Kynoar in mass ratio 96:2.2:1.8 in 1-METHYLPYRROLIDONE (NMP) solvent, mix and make anode sizing agent, then be coated on aluminium foil and at 110 DEG C after drying cold pressing, itemize, cutting edge, tab welding, make positive plate.
The preparation of negative plate:
By graphite, conductive carbon, thickener sodium carboxymethylcellulose, binding agent butadiene-styrene rubber in mass ratio 95:1.5:1.5:2.0 in deionized water, mix and make cathode size, then be coated on Copper Foil and at 85 DEG C after drying cold pressing, itemize, cutting edge, tab welding, make negative plate.
Barrier film:
Get thickness and be the polyethylene micropore film of 9 μ m as barrier film, barrier film is barrier film.
The preparation of battery:
Above-mentioned positive plate, barrier film, negative plate are wound into battery core, then this battery core are placed in to aluminium plastic packaging bag, inject electrolyte, through encapsulating, change into, the operation such as capacity, make battery; Wherein electrolyte comprises that mass ratio is ethylene carbonate, dimethyl carbonate and the methyl ethyl carbonate of 1:2:1, and lithium hexafluoro phosphate, and the concentration of lithium hexafluoro phosphate is 1mol/L.
comparative example 2
This comparative example and comparative example 1 are similar, and wherein the preparation of the preparation of positive plate, negative plate and the preparation of battery are identical with comparative example 1, repeat no more, and barrier film is different from comparative example 1, below barrier film and preparation thereof are elaborated:
Barrier film:
Get thickness and be the polyethylene micropore film of 9 μ m as barrier film.
The preparation of porous dielectric layer slurry (being mixture A):
In deionized water, first add the polyacrylate dispersion (in the aqueous solution, the content of polyacrylate is 40wt%) of 15wt% to stir 1h, then add the Al of 85wt%
2o
3particle, stirs after 2h, then in grinding in ball grinder 1h, prepares insulating barrier slurry, and the solid content in insulating barrier slurry is 60wt%, Al
2o
3the average grain diameter of particle is 0.5 μ m, and particle size distribution is 0.1 ~ 3 μ m.
The preparation of barrier film:
The mode of use intaglio plate coating on barrier film, is porous dielectric layer after insulating barrier slurry drying by insulating barrier slurry uniform fold, and the thickness of porous dielectric layer is 6 μ m, then, then to cutting with the barrier film of 1 layer of porous dielectric layer, cut-parts.
embodiment 1
The present embodiment improves on the basis of comparative example 2, and wherein the preparation of the preparation of positive plate, negative plate and the preparation of battery are identical with comparative example 1, repeat no more, and barrier film is different from comparative example 2, below barrier film and preparation thereof is elaborated:
Barrier film:
Get thickness and be the polyethylene micropore film of 9 μ m as barrier film.
The preparation of porous dielectric layer slurry (being mixture A):
1): in deionized water, first add the polyacrylate dispersion (in the aqueous solution, the content of polyacrylate is 40wt%) of 40wt% to stir 1h, then add the Al of 60wt%
2o
3particle, stirs after 2h, then in grinding in ball grinder 1h, prepares insulating barrier slurry 1, and the solid content in insulating barrier slurry 1 is 30wt%, Al
2o
3the average grain diameter of particle is 0.2 μ m, and particle size distribution is 0.08 ~ 2 μ m;
2): in deionized water, first add the polyacrylate dispersion (in the aqueous solution, the content of polyacrylate is 40wt%) of 20wt% to stir 1h, then add the Al of 80wt%
2o
3particle, stirs after 2h, then in grinding in ball grinder 1h, prepares insulating barrier slurry 2, and the solid content in insulating barrier slurry 2 is 30wt%, Al
2o
3the average grain diameter of particle is 6 μ m, and particle size distribution is 0.5 ~ 10 μ m;
The preparation of barrier film: first use the mode of intaglio plate coating that insulating barrier slurry 1 is covered on surface of barrier film, after insulating barrier slurry 1 is dry, be insulating barrier 1, the thickness of insulating barrier 1 is 2 μ m, and then use the mode of intaglio plate coating insulating barrier slurry 2 to be covered on the barrier film that is coated with insulating barrier 1, after insulating barrier slurry 2 is dry, be insulating barrier 2, the thickness of insulating barrier 2 is 8 μ m, then to cutting with the barrier film of 2 layers of porous dielectric layer, and cut-parts.
embodiment 2
The present embodiment improves on the basis of embodiment 1, and wherein the preparation of the preparation of positive plate, negative plate and the preparation of battery are identical with embodiment 1, repeat no more herein, and barrier film is different from embodiment 1, below barrier film and preparation thereof is elaborated:
Barrier film:
Get thickness and be the polyethylene micropore film of 9 μ m as barrier film.
The preparation of porous dielectric layer slurry (being mixture A):
1): in deionized water, first add the polyacrylate dispersion (in the aqueous solution, the content of polyacrylate is 40wt%) of 40wt% to stir 1h, then add the Al of 60wt%
2o
3particle, stirs after 2h, then in grinding in ball grinder 1h, prepares insulating barrier slurry 1, and the solid content in insulating barrier slurry 1 is 20wt%, Al
2o
3the average grain diameter of particle is 0.2 μ m, and particle size distribution is 0.08 ~ 2 μ m;
2): in deionized water, first add the polyacrylate dispersion (in the aqueous solution, the content of polyacrylate is 40wt%) of 25wt% to stir 1h, then add the Al of 75wt%
2o
3particle, stirs after 2h, then in grinding in ball grinder 1h, prepares insulating barrier slurry 2, and the solid content in insulating barrier slurry 2 is 20wt%, Al
2o
3the average grain diameter of particle is 0.8 μ m, and particle size distribution is 0.2 ~ 3 μ m;
3): in deionized water, first add the polyacrylate dispersion (in the aqueous solution, the content of polyacrylate is 40wt%) of 10wt% to stir 1h, then add the Al of 90wt%
2o
3particle, stirs after 2h, then in grinding in ball grinder 1h, prepares insulating barrier slurry 3, and the solid content in insulating barrier slurry 3 is 20wt%, Al
2o
3the average grain diameter of particle is 1.5 μ m, and particle size distribution is 0.4 ~ 5 μ m;
The preparation of barrier film: first use the mode of intaglio plate coating that insulating barrier slurry 1 is covered on surface of barrier film, after insulating barrier slurry 1 is dry, be insulating barrier 1 g201, the thickness of insulating barrier 1 g201 is 2 μ m, the mode that re-uses intaglio plate coating covers insulating barrier slurry 2 on the barrier film that is coated with insulating barrier 1 g201, after insulating barrier slurry 2 is dry, be insulating barrier 2 g202, the thickness of insulating barrier 2 g202 is 2 μ m, then use the mode of intaglio plate coating insulating barrier slurry 3 to be covered on the barrier film that is coated with insulating barrier 2 g202, after insulating barrier slurry 3 is dry, be insulating barrier 3 g202, the thickness of insulating barrier 3 g202 is 2 μ m, then the barrier film of being with the porous dielectric layer that haves three layers is cut, cut-parts, as shown in Figure 1, the number of plies of its multi-layer porous insulating barrier g2 is 3 layers to the structure of the present embodiment Separator for Lithium-ion battery, is respectively insulating barrier 1 g201, insulating barrier 2 g202 and insulating barrier 3 g203.The hole g204 of porous dielectric layer of the present invention refers to the gap forming between inorganic particulate, and aperture is the size of IDS.When the number of plies n of multi-layer porous insulating barrier is the numerical value beyond 3, structure and Fig. 1 are similar, make no longer separately schematic diagram.
Can also prepare and be with multi-layer porous insulating barrier according to the method for embodiment 1 and embodiment 2, and the barrier film of its number of plies n >=4, as 4 layers, 6 layers, 8 layers, 10 layers etc., no longer describe with more embodiment herein.
embodiment 3
The present embodiment improves on the basis of embodiment 1, and wherein the preparation of the preparation of positive plate, negative plate and the preparation of battery are identical with embodiment 1, repeat no more herein, and barrier film is different from embodiment 1, below barrier film and preparation thereof is elaborated:
Barrier film:
Get thickness and be the non-woven thin-film of 20 μ m as barrier film.
The preparation of porous dielectric layer slurry (being mixture A):
1): in 1-METHYLPYRROLIDONE, first add the Kynoar of 3wt% to stir 1h at 45 DEG C, then add the TiO of 97wt%
2particle, stirs after 2h, then in grinding in ball grinder 1h, prepares insulating barrier slurry 1, and the solid content in insulating barrier slurry 1 is 65wt%, TiO
2the average grain diameter of particle is 0.05 μ m, and particle size distribution is 0.01 ~ 0.5 μ m;
2): in 1-METHYLPYRROLIDONE, first add the Kynoar of 0.5wt% to stir 1h at 45 DEG C, then add the TiO of 99.5wt%
2particle, stirs after 2h, then in grinding in ball grinder 1h, prepares insulating barrier slurry 2, and the solid content in insulating barrier slurry 2 is 50wt%, TiO
2the average grain diameter of particle is 0.2 μ m, and particle size distribution is 0.08 ~ 1.0 μ m;
The preparation of barrier film: first use the mode of die head coating that insulating barrier slurry 1 is covered on surface of barrier film, after insulating barrier slurry 1 is dry, be insulating barrier 1, thickness is 0.5 μ m, the mode that re-uses die head coating covers insulating barrier slurry 2 on the barrier film that is coated with insulating barrier 1, after insulating barrier slurry 2 is dry, be insulating barrier 2, thickness is 0.5 μ m, and cut-parts are for subsequent use.
embodiment 4
The present embodiment improves on the basis of embodiment 1, and wherein the preparation of the preparation of positive plate, negative plate and the preparation of battery are identical with embodiment 1, repeat no more herein, and barrier film is different from embodiment 1, below barrier film and preparation thereof is elaborated:
Barrier film:
Get thickness and be the polypropylene microporous film of 12 μ m as barrier film.
The preparation of porous dielectric layer slurry (being mixture A):
1): in deionized water, first add the styrene-butadiene polymer of 10wt% to stir 1h, then add the Al of 90wt%
2o
3particle, stirs after 2h, then in grinding in ball grinder 1h, prepares insulating barrier slurry 1, and the solid content in insulating barrier slurry 1 is 50wt%, Al
2o
3the average grain diameter of particle is 0.2 μ m, and particle size distribution is 0.08 ~ 2 μ m;
2): in deionized water, first add the styrene-butadiene polymer of 10wt% to stir 1h, then add the Al of 90wt%
2o
3particle, stirs after 2h, then in grinding in ball grinder 1h, prepares insulating barrier slurry 1, and the solid content in insulating barrier slurry 1 is 50wt%, Al
2o
3the average grain diameter of particle is 4 μ m, and particle size distribution is 0.5 ~ 6 μ m;
The preparation of barrier film: first use the mode of dip-coating insulating barrier slurry 1 to be covered on two surfaces of barrier film, after insulating barrier slurry 1 is dry, be insulating barrier 1, its thickness is 2 μ m, the mode that re-uses dip-coating covers insulating barrier slurry 2 on the barrier film that is coated with insulating barrier 1, after dry, be insulating barrier 2, thickness is 8 μ m.
Wherein inorganic particulate is except above-mentioned Al
2o
3particle, TiO
2particle, can also select any one or a few in calcium oxide, zinc oxide, magnesium oxide, silicon dioxide, zirconium dioxide, tin ash, ceria, alundum (Al2O3), calcium carbonate, barium titanate or Al
2o
3particle, TiO
2particle and wherein one or more combination.
Wherein binding agent is except above-mentioned preferred polyacrylate, Kynoar and styrene-butadiene polymer, also can select at least one in Kynoar-hexafluoropropylene, polyacrylic acid, polymethylacrylic acid, polyacrylate, polymethyl methacrylate, polyacrylonitrile, sodium carboxymethylcellulose, butadiene-acrylonitrile polymer, polyvinylpyrrolidone, polyacrylic acid-styrene, or wherein any one or combination multiple and polyacrylate, Kynoar and/or styrene-butadiene.Can be applicable to polyacrylate of the present invention and can be polymethyl acrylate, polyethyl acrylate etc.
Wherein solvent is except above-mentioned deionized water, 1-METHYLPYRROLIDONE, can also select in oxolane, methylethylketone, dimethyl formamide, dimethylacetylamide, tetramethylurea, tetramethyl phosphate, acetone, carrene, chloroform, dimethylformamide, 1-METHYLPYRROLIDONE, cyclohexane, water, alcohol any one or multiple, or deionized water, 1-METHYLPYRROLIDONE and wherein one or more combination.
The mode that the mixture wherein inorganic particulate and binding agent being formed is coated in barrier film surface also can be selected roller coat, scraper to shift and be coated with, can also be with the combination of several coating methods while being coated with multilayer mixture.
Wherein the mass ratio of the inorganic particulate on porous dielectric layer and binding agent also can be preferably other ratio within the scope of 50:50 ~ 99.9:0.1, and the inorganic particulate on the hole insulating barrier of different layers can be different from the mass ratio of binding agent; The thickness of each porous dielectric layer of barrier film also can be other value within the scope of 0.4 ~ 10 μ m, as 1.0 μ m, 3.5 μ m, 5 μ m, 7 μ m and 10 μ m etc., preferably 1 ~ 6 μ m, the thickness of porous dielectric layer can be adjusted as required, if when the number of plies of porous dielectric layer is more, every layer of porous dielectric layer can be thinner, as:
The thickness of n=2 porous dielectric layer can be selected 5 μ m
The thickness of n=3 porous dielectric layer can be selected 3.5 μ m
Wherein the concentration of mixture A can be selected other value within the scope of 10 ~ 70wt%, and as 10wt%, 35wt%, 60wt% and 70wt% etc., preferred concentration is 20 ~ 60wt%.
Wherein to select average grain diameter be the inorganic particulate of 0.05 ~ 0.2 μ m to insulating barrier 1, and particle size distribution is 0.01 ~ 2 μ m, and preferably average grain diameter is the inorganic particulate of 0.08 ~ 0.15 μ m, and particle size distribution is 0.02 ~ 1.8 μ m; It is the inorganic particulate of 1 ~ 10 μ m that insulating barrier n selects average grain, particle size range is 0.1 ~ 12 μ m, preferably average grain is the inorganic particulate of 0.3 ~ 8 μ m, between insulating barrier 1 and insulating barrier n, can be coated with as required layer of cloth 2 to insulating barrier n-1, insulating barrier 2 to the average grain diameter of the inorganic particulate that insulating barrier n-1 selects is 0.2 ~ 8 μ m, particle size distribution is 0.08 ~ 10 μ m, and forms bore diameter gradient variation, and the bore diameter gradient finally forming from insulating barrier 1 to insulating barrier n changes.Time prepared by barrier film, be first coated with the insulating barrier 1 near barrier film side, be then coated with successively layer of cloth 2, insulating barrier 3 ..., insulating barrier n.
experimental example 1
Carry out thermal contraction test for the barrier film in above comparative example and embodiment
Thermal contraction test: the square sample that barrier film is die-cut into 100X100mm, indicate MD and TD direction, measure initial MD and the length of TD, put it in the baking oven of 130 degree and toast 2H, after taking out, the length of the rear MD of test baking and TD direction, calculates percent thermal shrinkage=[(size after the size-baking before baking)/red size before examination] X100%.Acquired results is in table 1
Table 1 comparative example and embodiment barrier film percent thermal shrinkage
As known from Table 1, the thermal contraction of the barrier film forming at barrier film surface-coated one deck porous dielectric layer obviously improves, and the improvement of the multi-layer porous insulating barrier thermal contraction that use bore diameter gradient changes is more obvious.
experimental example 2
Carry out discharge-rate test and cycle performance test for the lithium ion battery in above comparative example and embodiment
Discharge-rate test: lithium ion battery is first adopted at 25 DEG C the multiplying power of 0.5C charge, 0.2C multiplying power discharging, records discharge capacity; Then carry out the charging of 0.5C multiplying power, 0.5C multiplying power discharging, records discharge capacity; Then carry out the charging of 0.5C multiplying power, 1.0C multiplying power discharging, records discharge capacity; Then carry out the charging of 0.5C multiplying power, 1.5C multiplying power discharging, records discharge capacity again; Finally carry out the charging of 0.5C multiplying power, 2.0C multiplying power discharging, records discharge capacity.Capability retention=(discharge capacity under the discharge capacity/0.2C multiplying power under each multiplying power) X100% under variant discharge-rate.Acquired results is in table 2
Capability retention under table 2 comparative example discharge-rates different from embodiment
As known from Table 2, be contained in barrier film surface-coated and have the lithium ion battery of the barrier film of the multi-layer porous insulating barrier in gradient aperture, battery power is learned performance and is obviously promoted, and gradient is less, and dynamic performance promotes more obvious.
experimental example 3
Carry out cycle performance test for the lithium ion battery in above comparative example and embodiment
Cycle performance test: lithium ion battery is adopted under 25 degree to the multiplying power charging of 0.5C, the multiplying power discharging of 0.5C, carry out successively 500 circulations, battery capacity under each loop test 0.5C multiplying power, and compare with the capacity under front battery 25 degree of circulation, capability retention after computation cycles, capability retention=(capacity before the capacity/circulation after circulation under 0.5C multiplying power under battery 25 degree) X100%.Acquired results is in table 3
Table 3 comparative example and embodiment circulation volume conservation rate
As known from Table 3, the multi-layer porous insulating barrier of gradient promotes very obvious to the cycle performance of lithium rechargeable battery.
experimental example 4
For carrying out drift bolt safety test with the rear battery of circulation before the lithium ion battery circulation in above comparative example and embodiment
Drift bolt test: first battery is completely filled, then test according to the standard of UL1642, nail diameter is 2.5mm, and drift bolt speed is 100mm/s.Respectively the battery before circulation and the battery after 500 circulations are carried out to drift bolt safety test.Test result is in table 4
The drift bolt test result of battery before and after table 4 circulation
As known from Table 4, barrier film surface-coated has after the multi-layer porous insulating barrier of bore diameter gradient, and security performance obviously improves, and after 500 circulations, battery has all kept very high security performance.
The announcement of book and elaboration according to the above description, those skilled in the art in the invention can also carry out suitable change and amendment to above-mentioned execution mode.Therefore, the present invention is not limited to embodiment disclosed and described above, also should fall in claim of the present invention and protection range modifications and changes more of the present invention.In addition,, although used some specific terms in this specification, these terms just for convenience of description, do not form any restriction to the present invention.
Claims (10)
1. a Separator for Lithium-ion battery, it is characterized in that: comprise barrier film and at least one the lip-deep multi-layer porous insulating barrier that is arranged on barrier film for separating two kinds of pole pieces of battery, porous dielectric layer comprises inorganic particulate and binding agent, the mean particle size of the inorganic particulate of every layer of porous dielectric layer becomes gradually large on barrier film surface on the direction of pole piece, and makes the pore size of multi-layer porous insulating barrier form graded from small to large from barrier film to pole piece direction; The number of plies that is positioned at the porous dielectric layer of the same side of barrier film is n, n >=2, be insulating barrier 1 apart from the nearest one deck porous dielectric layer in barrier film surface, be insulating barrier n apart from barrier film surface one deck porous dielectric layer farthest, between insulating barrier 1 and insulating barrier n, be disposed with insulating barrier 2, insulating barrier 3 ... with insulating barrier n-1; In lithium rechargeable battery, there is not oxidation or reduction in inorganic particulate.
2. a kind of Separator for Lithium-ion battery according to claim 1, is characterized in that: the average grain diameter of the described inorganic particulate that described insulating barrier 1 is selected is 0.05 ~ 0.2 μ m, and particle size distribution is 0.01 ~ 2 μ m; Described insulating barrier 2 is 0.2 ~ 8 μ m to the average grain diameter of the inorganic particulate that described insulating barrier n-1 selects, and particle size distribution is 0.08 ~ 10 μ m; The average grain diameter of the inorganic particulate that insulating barrier n selects is 1 ~ 10 μ m, and particle size distribution is 0.1 ~ 12 μ m; The number of plies n of described porous dielectric layer is 2 ~ 10, and the thickness of every layer of porous dielectric layer is 0.4 ~ 10 μ m.
3. a kind of Separator for Lithium-ion battery according to claim 2, is characterized in that: the average grain diameter of the described inorganic particulate that described insulating barrier 1 is selected is preferably 0.08 ~ 0.15 μ m, and particle size distribution is 0.02 ~ 1.8 μ m; The average grain diameter of the inorganic particulate that described insulating barrier n selects is 0.3 ~ 8 μ m, and particle size range is 0.1 ~ 10 μ m; The thickness of every layer of described porous dielectric layer is 1 ~ 6 μ m.
4. according to a kind of Separator for Lithium-ion battery described in arbitrary claim in claims 1 to 3, it is characterized in that: the material of described barrier film is polyethylene, polypropylene, polyimides or nonwoven fabrics.
5. according to a kind of Separator for Lithium-ion battery described in arbitrary claim in claims 1 to 3, it is characterized in that: described inorganic particulate be in calcium oxide, zinc oxide, magnesium oxide, titanium dioxide, silicon dioxide, zirconium dioxide, tin ash, ceria, alundum (Al2O3), calcium carbonate and barium titanate any one or multiple.
6. according to a kind of Separator for Lithium-ion battery described in arbitrary claim in claims 1 to 3, it is characterized in that: described binding agent be in styrene-butadiene polymer, Kynoar, Kynoar-hexafluoropropylene, polyacrylic acid, polymethylacrylic acid, polyacrylate, polymethyl methacrylate, polyacrylonitrile, sodium carboxymethylcellulose, butadiene-acrylonitrile polymer, polyvinylpyrrolidone and polyacrylic acid-styrene any one or multiple.
7. according to a kind of Separator for Lithium-ion battery described in arbitrary claim in claims 1 to 3, it is characterized in that: the mass ratio of described inorganic particulate and described binding agent is 50:50 ~ 99.9:0.1, described porous dielectric layer is arranged on described barrier film by the mode applying.
8. according to the preparation method of a kind of Separator for Lithium-ion battery described in arbitrary claim in claim 1 to 7, it is characterized in that: its step comprises as follows:
A) dispersed with stirring of described inorganic particulate and described binding agent: binding agent is dissolved in solvent to form polymer solution, then adds inorganic particulate and mix, obtain mixture A, the concentration of mixture A is 10 ~ 70wt%; Solvent be can dissolve binding agent, can dispersed inorganic particulate and be easy to the solvent of removing applying dry run;
B) on the surface of described barrier film, apply described multi-layer porous insulating barrier, make Separator for Lithium-ion battery: first the mixture A of the mean particle size minimum of the inorganic particulate comprising is coated to barrier film surface, after dry, form described insulating barrier 1, again the mean particle size of the inorganic particulate comprising is become gradually to large mixture A and be coated to successively barrier film surface, form described insulating barrier 2, insulating barrier 3 ... with insulating barrier n, insulating barrier 1, insulating barrier 2, insulating barrier 3 ... form multi-layer porous insulating barrier with insulating barrier n, after every coating one deck mixture A, need to be first dried processing and apply again lower one deck mixture A, after applying n layer mixture A, be also dried processing.
9. the preparation method of a kind of Separator for Lithium-ion battery according to claim 8, is characterized in that: described solvent is one or more in oxolane, methylethylketone, dimethyl formamide, dimethylacetylamide, tetramethylurea, tetramethyl phosphate, acetone, carrene, chloroform, dimethylformamide, 1-METHYLPYRROLIDONE, cyclohexane, water, alcohol; The concentration of described mixture A is 20 ~ 60wt%; The mode that described step b) is coated in mixture A barrier film surface be dip-coating, die head painting, roller coat, scraper shift be coated with and intaglio plate in being coated with any one or multiple.
10. lithium rechargeable battery, comprises positive plate, negative plate, electrolyte and the barrier film between positive plate and negative plate, it is characterized in that: described barrier film is a kind of Separator for Lithium-ion battery described in arbitrary claim in claim 1 to 6.
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| CN108258299A (en) * | 2018-01-10 | 2018-07-06 | 杭州华选信息科技有限公司 | A kind of lithium-ion-power cell |
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| CN109950461A (en) * | 2019-04-23 | 2019-06-28 | 江苏塔菲尔新能源科技股份有限公司 | A kind of diaphragm and preparation method thereof and battery |
| CN112490584A (en) * | 2020-03-30 | 2021-03-12 | 万向一二三股份公司 | Lithium ion battery diaphragm with alternate coating structure and preparation method thereof |
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| CN109950461A (en) * | 2019-04-23 | 2019-06-28 | 江苏塔菲尔新能源科技股份有限公司 | A kind of diaphragm and preparation method thereof and battery |
| CN112490584A (en) * | 2020-03-30 | 2021-03-12 | 万向一二三股份公司 | Lithium ion battery diaphragm with alternate coating structure and preparation method thereof |
| CN112490584B (en) * | 2020-03-30 | 2022-07-29 | 万向一二三股份公司 | Lithium ion battery diaphragm with alternate coating structure and preparation method thereof |
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