WO2013153954A1 - 電池用セパレータ及びその製造方法 - Google Patents
電池用セパレータ及びその製造方法 Download PDFInfo
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- WO2013153954A1 WO2013153954A1 PCT/JP2013/059164 JP2013059164W WO2013153954A1 WO 2013153954 A1 WO2013153954 A1 WO 2013153954A1 JP 2013059164 W JP2013059164 W JP 2013059164W WO 2013153954 A1 WO2013153954 A1 WO 2013153954A1
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- particles
- porous membrane
- porous film
- fluororesin
- battery separator
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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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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
- B32B27/322—Layered products comprising a layer of synthetic resin comprising polyolefins comprising halogenated polyolefins, e.g. PTFE
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/403—Manufacturing processes of separators, membranes or diaphragms
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
- H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
- H01M50/417—Polyolefins
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
- H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
- H01M50/42—Acrylic resins
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
- H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
- H01M50/426—Fluorocarbon polymers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/431—Inorganic material
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/446—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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
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- 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
- H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
- H01M50/491—Porosity
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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
Definitions
- the porous membrane made of thermoplastic resin is widely used as a material separation material, a permselective material and a separation material.
- a material separation material for example, battery separators for lithium ion secondary batteries, nickel-hydrogen batteries, nickel-cadmium batteries, polymer batteries, separators for electric double layer capacitors, reverse osmosis filtration membranes, ultrafiltration membranes, microfiltration membranes, etc. Filters, moisture permeable waterproof clothing, medical materials, etc.
- a polyethylene porous membrane is suitably used as a separator for a lithium ion secondary battery.
- the reason for this is not only the characteristics of excellent electrical insulation, ion permeability by impregnation with electrolyte, excellent resistance to electrolyte and oxidation, but also at a temperature of about 120 to 150 ° C. during abnormal battery temperature rise. This is because it also has a hole closing effect that cuts off current and suppresses excessive temperature rise. However, if the temperature continues to rise even after the pores are closed for some reason, a film breakage may occur at a certain temperature due to a decrease in viscosity of the melted polyethylene constituting the film and a contraction of the film.
- separators are deeply involved in battery characteristics, battery productivity, and battery safety. Excellent mechanical characteristics, heat resistance, permeability, dimensional stability, pore clogging characteristics (shutdown characteristics), melt-breaking characteristics (meltdown) Characteristics) and the like are required.
- lithium-ion secondary batteries are strongly required to improve battery productivity. For this reason, separators for lithium-ion secondary batteries will increasingly have higher processability in the battery assembly process ( It is expected that electrolyte solution permeability and low curl properties are required.
- Patent Document 1 discloses a separator for a lithium ion secondary battery in which a heat-resistant nitrogen-containing aromatic polymer containing ceramic powder is laminated on a polyolefin porous membrane.
- Patent Documents 2 and 3 disclose battery separators in which a heat-resistant layer containing inorganic particles and polyamideimide is laminated on a polyolefin porous film.
- Patent Document 4 discloses a battery separator obtained by immersing a polyolefin porous film in a dope mainly composed of polyvinylidene fluoride as a heat-resistant resin and inorganic particles.
- Patent Document 5 discloses a battery separator obtained by immersing a polyolefin porous membrane in a dope mainly composed of carboxymethyl cellulose and inorganic particles.
- the ceramic powder and the heat-resistant nitrogen-containing aromatic polymer are in a state of entering and adhering into the pores of the polyethylene porous membrane of the base material, so compared with the case of the polyolefin porous membrane alone.
- the air permeability resistance was greatly increased. Also, the electrolyte penetration was not satisfactory.
- the air permeability resistance by the heat-resistant resin layer lamination on the polyolefin-based porous film as the base material there is no material that can satisfy all of the workability such as the rate of increase in electrolyte, electrolyte permeability, and low curl properties.
- the present invention has excellent heat resistance and workability in the battery assembly process, and the rate of increase in the air resistance is improved by infiltrating a trace amount of fluororesin, which is a heat resistant resin, into the deep pores of the polyolefin porous membrane. It is a combination of the characteristics that are difficult to achieve with the conventional technique of suppressing and improving the electrolyte permeability.
- the state of microscopic penetration means that the fluororesin layer (porous membrane B) is peeled from the polyolefin porous membrane (porous membrane A) and then subjected to infrared spectroscopic measurement (transmission method).
- the absorbance (absT (1200) ) of absorption having a peak in the vicinity of 1,200 cm ⁇ 1 belonging to the resin is in the range of 0.01 or more and 0.30 or less per 10 ⁇ m thickness of the porous film A. To do.
- the term “up to the deep part in the pore” as used herein refers to the fluororesin when the infrared spectroscopic measurement (reflection method) is performed from the polyolefin porous membrane surface side (surface opposite to the porous membrane B). It means that the absorbance (absR (1200) ) of absorption having a peak in the vicinity of 1,200 cm ⁇ 1 is in the range of 0.001 or more and 0.030 or less.
- the rate of increase in the air resistance is preferably 130% or less, more preferably 120% or less, and most preferably 110% or less.
- the battery separator of the present invention has the following configuration. That is, A separator for a battery in which a porous film A made of a polyolefin resin and a porous film B containing inorganic resin or cross-linked polymer particles are laminated on a porous film A, and the content of the particles is 80% of that of the porous film B.
- the battery separator satisfies the formulas 1 and 2 by weight% or more and 97% by weight or less, and the average particle diameter is 1.5 times or more and less than 50 times the average pore diameter of the porous membrane A.
- the method for producing the battery separator of the present invention comprises: It has a configuration. That is, A method for producing the battery separator, comprising the following steps (i) and (ii).
- the inorganic particles are preferably at least one selected from silica, titanium dioxide, and alumina.
- the crosslinked polymer particles are preferably at least one selected from crosslinked polystyrene particles, crosslinked acrylic resin particles, and crosslinked methyl methacrylate particles.
- a resin component mainly composed of a fluorine-based resin is present in a trace amount in the deep pores of the polyolefin-based porous membrane A, and has excellent heat resistance, workability and low curling property)
- it has a feature that the rate of increase in air permeability resistance due to the lamination of heat-resistant resin is extremely small, and further has excellent electrolyte solution permeability, so it is suitable for use as a separator for lithium ion secondary batteries can do.
- the battery separator of the present invention has a structure in which a porous film A made of a polyolefin resin and a porous film B containing a fluorine resin and inorganic particles or crosslinked polymer particles are laminated. Since the present invention has a specific varnish, which will be described later, and a highly controlled coating technique, the fluororesin has penetrated deep into the pores of the porous membrane A made of polyolefin resin. However, since the amount of fluorine resin entering the pores of the porous membrane A is very small, the rate of increase in air resistance due to the lamination of the fluorine resin is extremely small.
- porous membrane A used in the present invention will be described.
- the resin constituting the porous membrane A is a polyolefin resin, and may be a single material or a mixture of two or more different polyolefin resins, for example, a mixture of polyethylene and polypropylene, or a copolymer of different olefins. But you can. Particularly preferred are polyethylene and polypropylene. This is because, in addition to basic characteristics such as electrical insulation and ion permeability, the battery has a hole closing effect that cuts off current and suppresses excessive temperature rise when the battery temperature rises abnormally.
- the mass average molecular weight (Mw) of the polyolefin resin is not particularly limited, but is usually 1 ⁇ 10 4 to 1 ⁇ 10 7 , preferably 1 ⁇ 10 4 to 15 ⁇ 10 6 , more preferably 1 ⁇ 10 5. ⁇ 5 ⁇ 10 6 .
- the polyolefin resin preferably contains polyethylene.
- polyethylene examples include ultra high molecular weight polyethylene, high density polyethylene, medium density polyethylene, and low density polyethylene.
- the polymerization catalyst is not particularly limited, and examples thereof include a Ziegler-Natta catalyst, a Phillips catalyst, and a metallocene catalyst. These polyethylenes may be not only ethylene homopolymers but also copolymers containing small amounts of other ⁇ -olefins.
- ⁇ -olefins other than ethylene include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, (meth) acrylic acid, esters of (meth) acrylic acid, styrene, etc. Is preferred.
- Polyethylene may be a single material, but is preferably a polyethylene mixture composed of two or more types of polyethylene.
- a polyethylene mixture a mixture of two or more types of ultrahigh molecular weight polyethylenes having different Mw, similar high density polyethylene, medium density polyethylene and low density polyethylene may be used, or ultra high molecular weight polyethylene, high density polyethylene, A mixture of two or more polyethylenes selected from the group consisting of medium density polyethylene and low density polyethylene may be used.
- the polyethylene mixture Mw of 5 ⁇ 10 5 or more ultra-high molecular weight polyethylene and Mw of 1 ⁇ 10 4 or more, the mixture is preferably composed of a polyethylene of less than 5 ⁇ 10 5.
- the Mw of the ultra high molecular weight polyethylene is preferably 5 ⁇ 10 5 to 1 ⁇ 10 7 , more preferably 1 ⁇ 10 6 to 15 ⁇ 10 6 , and 1 ⁇ 10 6 to 5 ⁇ 10 6. Is particularly preferred.
- the polyethylene having an Mw of 1 ⁇ 10 4 or more and less than 5 ⁇ 10 5 any of high density polyethylene, medium density polyethylene and low density polyethylene can be used, and it is particularly preferable to use high density polyethylene.
- polyethylene with Mw of 1 ⁇ 10 4 or more and less than 5 ⁇ 10 5 two or more types having different Mw may be used, or two or more types having different densities may be used.
- the content of high molecular weight polyethylene in the polyethylene mixture is preferably 1% by weight or more, and preferably 10 to 80% by weight.
- the specific molecular weight distribution (Mw / Mn) of Mw and number average molecular weight (Mn) of the polyolefin resin is not particularly limited, but is preferably in the range of 5 to 300, more preferably 10 to 100. When the Mw / Mn is within this preferred range, the polyolefin solution can be easily extruded, while the strength of the resulting microporous film is excellent. Mw / Mn is used as a measure of the molecular weight distribution. That is, in the case of a single polyolefin, the larger this value, the wider the molecular weight distribution.
- the Mw / Mn of a single polyolefin can be appropriately adjusted by multistage polymerization of polyolefin.
- the Mw / Mn of the polyolefin mixture can be adjusted as appropriate by adjusting the molecular weight and mixing ratio of each component.
- phase structure of the porous membrane A varies depending on the production method. As long as the above various characteristics are satisfied, the phase structure according to the purpose can be freely given by the production method. There are foaming methods, phase separation methods, dissolution recrystallization methods, stretched pore opening methods, powder sintering methods, etc., among these porous membrane production methods. Among these, phase separation is performed in terms of uniform micropores and cost. The method is preferred.
- a polyolefin and a film-forming solvent are melt-kneaded, the obtained molten mixture is extruded from a die, and cooled to form a gel-like molding, and the obtained gel-like molding is obtained.
- examples thereof include a method of obtaining a porous film by stretching a material in at least a uniaxial direction and removing the film-forming solvent.
- the porous film A may be a single layer film or a multilayer film composed of two or more layers having different pore diameters and thermal characteristics.
- a method for producing a multilayer film composed of two or more layers for example, each of the polyolefins constituting the a layer and the b layer is melt-kneaded with a film-forming solvent, and the resulting molten mixture is transferred from each extruder to one die.
- Either a method of supplying and co-extrusing the gel sheets constituting each component, or a method of heat-sealing the gel sheets constituting the respective layers superposed can be produced.
- the coextrusion method is more preferable because it is easy to obtain a high interlayer adhesive strength, and it is easy to form communication holes between layers, so that high permeability is easily maintained and productivity is excellent.
- the porous membrane A needs to have a function of blocking pores when the charge / discharge reaction is abnormal.
- the melting point (softening point) of the constituent resin is preferably 70 to 150 ° C., more preferably 80 to 140 ° C., and most preferably 100 to 130 ° C.
- the battery can be used because the pore blocking function does not appear during normal use.
- the pore blocking function is quickly developed. Therefore, sufficient safety can be secured.
- the film thickness of the porous membrane A is preferably 5 ⁇ m or more and less than 50 ⁇ m.
- the upper limit of the film thickness is more preferably 40 ⁇ m, and most preferably 30 ⁇ m.
- the lower limit of the film thickness is more preferably 10 ⁇ m, and most preferably 15 ⁇ m.
- the upper limit of the air permeability resistance (JIS P8117) of the porous membrane A is preferably 500 sec / 100 ccAir, more preferably 400 sec / 100 ccAir, and most preferably 300 sec / 100 ccAir.
- the lower limit of the air resistance is preferably 50 sec / 100 ccAir, more preferably 70 sec / 100 ccAir, and most preferably 100 sec / 100 ccAir.
- the battery has sufficient charge / discharge characteristics of the battery, in particular, ion permeability (charge / discharge operating voltage), battery life (close to the amount of electrolyte retained). On the other hand, sufficient mechanical strength and insulation can be obtained, and there is no possibility of short circuit during charging / discharging.
- the upper limit of the porosity of the porous membrane A is preferably 70%, more preferably 60%, and most preferably 55%.
- the lower limit of the porosity is preferably 30%, more preferably 35%, and most preferably 40%.
- the battery has sufficient charge / discharge characteristics of the battery, in particular, ion permeability (charge / discharge operating voltage), battery life (close to the amount of electrolyte retained). On the other hand, sufficient mechanical strength and insulation can be obtained, and there is no possibility of short circuit during charging / discharging.
- the average pore diameter of the porous membrane A is preferably 0.01 to 0.5 ⁇ m, more preferably 0.1 to 0.3 ⁇ m, because it greatly affects the pore closing rate.
- the average pore diameter of the porous membrane A is within this preferred range, the polyamideimide resin is likely to enter the deep pores of the porous membrane A, and as a result, sufficient electrolyte solution permeability can be obtained.
- the air resistance is not greatly deteriorated, and on the other hand, the response to the temperature of the hole closing phenomenon is sufficiently fast, and the hole closing temperature due to the heating rate does not shift to the high temperature side.
- porous membrane B used in the present invention will be described.
- the porous membrane B includes a fluorine resin and inorganic particles or crosslinked polymer particles.
- the porous membrane B plays a role of supporting and reinforcing the porous membrane A due to its heat resistance. Therefore, the glass transition temperature of the fluororesin is preferably 150 ° C. or higher, more preferably 180 ° C. or higher, most preferably 210 ° C. or higher, and the upper limit is not particularly limited. When the glass transition temperature is higher than the decomposition temperature, the decomposition temperature may be in the above range. When the glass transition temperature of the polyamide-imide resin constituting the porous membrane B is within this preferred range, a sufficient heat-resistant membrane breaking temperature can be obtained and high safety can be ensured.
- the reason for using the fluorine-based resin is that it has good wettability with respect to a commonly used electrolytic solution (for example, polycarbonate-based electrolytic solution) and has excellent adhesion to the electrode.
- a commonly used electrolytic solution for example, polycarbonate-based electrolytic solution
- the fluororesin is at least one selected from the group consisting of vinylidene fluoride homopolymers, vinylidene fluoride / fluorinated olefin copolymers, vinyl fluoride homopolymers, and vinyl fluoride / fluorinated olefin copolymers. Is preferably used. Particularly preferred is polytetrafluoroethylene. These polymers have high affinity with non-aqueous electrolytes, are suitable for heat resistance, and have high chemical and physical stability against non-aqueous electrolytes. The affinity of can be maintained sufficiently.
- the porous membrane B is a fluorine-based resin solution (varnish) that is soluble in a fluorine-based resin and dissolved in a solvent miscible with water, and is applied to the predetermined porous membrane A. It can be obtained by phase-separating a solvent miscible with water and further putting it in a water bath (coagulation bath) to coagulate the fluororesin. If necessary, a phase separation aid may be added to the varnish.
- Solvents that can be used to dissolve the fluororesin include N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), phosphoric acid hexamethyltriamide (HMPA), N, N-dimethyl.
- DMAc N-dimethylacetamide
- NMP N-methyl-2-pyrrolidone
- HMPA phosphoric acid hexamethyltriamide
- N, N-dimethyl examples include formamide (DMF), dimethyl sulfoxide (DMSO), ⁇ -butyrolactone, chloroform, tetrachloroethane, dichloroethane, 3-chloronaphthalene, parachlorophenol, tetralin, and acetonitrile, which can be freely selected according to the solubility of the resin. .
- phase separation aid used in the present invention water, ethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexanediol and other alkylene glycols, polyethylene glycol, polypropylene glycol, polytetramethylene glycol and other polyalkylene glycols, water-soluble At least one selected from water-soluble polyester, water-soluble polyurethane, polyvinyl alcohol, carboxymethyl cellulose and the like, and the addition amount is preferably 1 to 9% by weight, more preferably 2 to 8% by weight, based on the weight of the varnish solution, More preferably, it is added in the range of 3 to 7% by weight.
- phase separation aids By mixing these phase separation aids into the varnish, it is possible to mainly control the air permeability resistance, the surface porosity, and the layer structure formation rate. By adding the phase separation aid in such a preferable range, the phase separation rate is remarkably increased. On the other hand, the coating liquid does not become cloudy at the mixing stage, and the resin component does not precipitate.
- the logarithmic viscosity of the fluororesin is preferably 0.5 dL / g or more.
- the lower limit of the logarithmic viscosity is preferably 1.8 dL / g or less.
- Solvents that can be used to dissolve the fluororesin are not particularly limited as long as they have resin solubility and affinity for the polyolefin porous membrane B.
- DMAc N-dimethylacetamide
- NMP N-methyl -2-pyrrolidone
- HMPA phosphoric acid hexamethyltriamide
- DMF N, N-dimethylformamide
- DMSO dimethyl sulfoxide
- ⁇ -butyrolactone chloroform, tetrachloroethane, dichloroethane, 3-chloronaphthalene, Parachlorophenol, tetralin, acetone, acetonitrile and the like can be mentioned.
- These solvents may be used alone or in combination.
- the upper limit of the resin concentration in the solution component when the particle component in the varnish is removed is preferably 3.5% by weight, more preferably 3.0% by weight, and the lower limit is preferably 1.0% by weight, more preferably. Is 1.5% by weight.
- inorganic particles or crosslinked polymer particles are present in the porous membrane B in order to reduce curling. Furthermore, the presence of inorganic particles or crosslinked polymer particles in the porous membrane B prevents the internal short circuit caused by the growth of the dendritic crystals of the electrode inside the battery (dendrite prevention effect), reduces the heat shrinkage rate, Effects such as imparting slipperiness can also be obtained.
- inorganic particles or crosslinked polymer particles may be added to the varnish.
- the upper limit of the particle content in the porous membrane B is preferably 97% by weight, more preferably 95% by weight.
- the lower limit is preferably 80% by weight, more preferably 85% by weight.
- the curl reduction effect is sufficient, while the ratio of the fluororesin is appropriate with respect to the total volume of the porous membrane B, and is deep in the pores of the porous membrane A. The resin penetrates sufficiently until sufficient adhesion of the porous membrane B is obtained.
- Inorganic particles include calcium carbonate, calcium phosphate, silica, crystalline glass filler, kaolin, talc, titanium dioxide, alumina, silica-alumina composite oxide particles, barium sulfate, calcium fluoride, lithium fluoride, zeolite, molybdenum sulfide. And mica.
- Alumina, titanium dioxide, and silica are easy to obtain and suitable from the viewpoint of cost.
- crosslinked polymer particles include crosslinked polystyrene particles, crosslinked acrylic resin particles, and crosslinked methyl methacrylate particles.
- the upper limit of the average particle diameter of these particles is 25 ⁇ m, preferably 5 ⁇ m, more preferably 1 ⁇ m, and the lower limit is 0.02 ⁇ m, preferably 0.10 ⁇ m, more preferably 0.3 ⁇ m.
- the relationship between the average pore size of the porous membrane A and the average particle size of these particles is that the average particle size of the particles is 1.5 times or more and 50 times or less than the average pore size of the polyolefin-based porous membrane A. Preferably they are 1.8 times or more and 20 times or less, More preferably, they are 2.0 times or more and 5 times or less.
- the average particle diameter of the particles is within this preferable range, the pores of the polyolefin-based porous membrane A are not blocked in a state where the fluorine-based resin and the particles are mixed, and a significant increase in the air resistance can be prevented. On the other hand, it is difficult for the particles to fall off in the battery assembling process, and a serious defect of the battery can be effectively prevented.
- phase separation aid may be used to increase the processing speed.
- the amount of the phase separation aid used is preferably less than 12% by mass, more preferably 6% by mass or less, and even more preferably 5% by mass or less based on the solvent component of the varnish.
- the film thickness of the porous membrane B is preferably 1 to 5 ⁇ m, more preferably 1 to 4 ⁇ m, and most preferably 1 to 3 ⁇ m. If the film thickness of the porous film B is within this preferred range, the film breaking strength and insulation can be secured when the porous film A is melted / shrinked at a melting point or higher, while curling is difficult to increase. Is easy to handle.
- the porosity of the porous membrane B is preferably 30 to 90%, more preferably 40 to 70%.
- the electrical resistance of the membrane does not become too high, and a large current can easily flow, while the membrane strength is sufficiently high.
- the air resistance of the porous membrane B is preferably 1 to 600 sec / 100 cc Air as measured by a method based on JIS P8117. More preferably, it is 50 to 500 sec / 100 ccAir, and further preferably 100 to 400 sec / 100 ccAir.
- the air permeability resistance of the porous membrane B is within this preferable range, the membrane strength is strong, while the cycle characteristics are also good.
- the air resistance of the battery separator of the present invention is preferably 50 to 800 sec / 100 ccAir, more preferably 100 to 500 sec / 100 ccAir, and most preferably 100 to 400 sec / 100 ccAir. If the air permeability resistance of the battery separator is within this preferable range, sufficient insulation can be obtained, and there is no possibility of causing clogging of foreign substances, short circuit, and film breakage, while the membrane resistance is not too high and can be used practically. The charge / discharge characteristics and life characteristics are obtained.
- the manufacturing process of the battery separator of the present invention includes the following steps (i) and (ii).
- the porous film B is a method in which a fluorine resin solution dissolved in a solvent miscible with water and a varnish mainly composed of particles is applied to the porous film A made of a predetermined polyolefin resin. Is obtained by laminating using, followed by placing in a specific humidity environment, separating the phase of the solvent miscible with the fluororesin and water, and adding it to a water bath (coagulation bath) to coagulate the fluororesin. .
- the porous film B is once coated on a base film (for example, a polypropylene film or a polyester film) and then placed in a specific humidity environment to separate the fluororesin component and the solvent component into a porous material.
- a base film for example, a polypropylene film or a polyester film
- the absT (1200) and absR (1200) can be within a predetermined range even in a method (transfer method) in which the porous film B is transferred to the porous film A and laminated.
- a zone placed in a specific humidity environment is allowed to pass for 3 seconds or more from the coating to the charging of the coagulation tank.
- the upper limit of the passage time is not particularly limited, but 30 seconds is sufficient. During this time, the fluororesin and the solvent are phase separated.
- Humidity Absolute The zone humidity limit is 10 g / m 3, preferably 9.5 g / m 3, more preferably from 9.0 g / m 3, the lower limit is 5 g / m 3, preferably 6 g / m 3, More preferably, the zone is managed at 7.0 g / m 3 .
- the fluororesin does not absorb moisture and gelation does not proceed, so that the fluororesin can be penetrated deep into the pores of the porous membrane A, and absR ( While 1220) does not become too small, the phase separation between the fluororesin and the solvent is sufficiently performed, and a significant increase in the air resistance can be prevented.
- the fluororesin component coagulates in a three-dimensional network.
- the immersion time in the coagulation bath is preferably 3 seconds or more. When the immersion time in the coagulation bath is within this preferable range, the resin component is sufficiently coagulated.
- the upper limit of the immersion time is not limited, but 10 seconds is sufficient. The upper limit is not limited, but 10 seconds is sufficient.
- the unwashed porous membrane is immersed in an aqueous solution containing 1 to 20% by weight, more preferably 5 to 15% by weight of a good solvent for the fluororesin constituting the porous membrane B, and purified water
- a final battery separator can be obtained through a washing process using, and a drying process using hot air of 100 ° C. or lower.
- the resin penetrates thinly into the deep pores of the polyolefin-based porous membrane A, the electrolyte permeability is good, and the rate of increase in air permeability can be reduced.
- the battery separator of the present invention is desirably stored in a dry state, but when it is difficult to store in a completely dry state, it is preferable to perform a vacuum drying treatment at 100 ° C. or lower immediately before use.
- the battery separator of the present invention is a battery separator for secondary batteries such as nickel-hydrogen batteries, nickel-cadmium batteries, nickel-zinc batteries, silver-zinc batteries, lithium ion secondary batteries, lithium polymer secondary batteries, etc. Although it can be used, it is particularly preferable to use it as a separator of a lithium ion secondary battery.
- Fluorine-based resin component derived 1,200Cm -1 vicinity of absorbance obtains the value of the absorption peak height having an absorption maximum in the region of 1,200 ⁇ 20 cm -1, film of the porous membrane A The absorbance per 10 ⁇ m thickness was converted.
- the base line was a line connecting the skirts on both sides of the maximum absorption peak. In addition, smoothing was performed when the noise was large. It was confirmed in advance that all blank samples (uncoated porous film A) had no absorption having a maximum in the corresponding region.
- the fluorine-based resin component derived 1,200Cm -1 vicinity of absorbance was determined from the value of the absorption peak height having an absorption maximum in the region of 1,200 ⁇ 20 cm ⁇ 1 .
- (3) Film thickness The film thickness of the porous membrane A and the battery separator was measured using a contact-type film thickness meter (Digital Micrometer M-30 manufactured by Sony Manufacturing Co., Ltd.). The film thickness of the porous membrane A was evaluated based on a sample obtained by removing the porous membrane B from the battery separator.
- the film thickness of the porous film B was evaluated from the difference between the film thickness of the battery separator and the film thickness of the porous film A.
- (4) Porosity A 10 cm square sample was prepared, its sample volume (cm 3 ) and mass (g) were measured, and the porosity (%) was calculated from the obtained result using the following formula.
- Porosity (1 ⁇ mass / (resin density ⁇ sample volume)) ⁇ 100
- the sample volume (cm 3 ) is determined by 10 cm ⁇ 10 cm ⁇ thickness (cm).
- Adhesion of porous film B peel strength
- An adhesive tape manufactured by Nichiban Co., Ltd., No. 405; 24 mm width
- peel strength at the interface between A and the porous membrane B was measured, measured continuously between 100 mm from the start of measurement to the end of measurement, the average value of the measured values was calculated, and the peel strength was converted to a width of 25 mm. It was.
- the porous film B may not be completely peeled off at the peeling interface, and the porous film B may remain in the porous film A. In this case as well, the interface between the porous film A and the porous film B may be present.
- the peel strength was calculated.
- (6) Rate of increase in air permeability resistance Using a Gurley-type densometer type B manufactured by Tester Sangyo Co., Ltd., the battery separator or porous membrane A is not wrinkled between the clamping plate and the adapter plate. And measured according to JISP 8117. Arbitrary three places were measured and the average value was made into air permeability resistance. The air permeability resistance of only the porous membrane A of each comparative example and the air resistance of the battery separator were obtained, and the air resistance increase rate was obtained from the following equation.
- Glass transition temperature A fluororesin solution or a resin solution in which a battery separator is immersed in a good solvent to dissolve only the fluororesin is used with a PET film (Toyobo Co., Ltd. E5001) or a polypropylene film (Toyobo). Pyrene (registered trademark) -OT) manufactured by Co., Ltd. with an appropriate gap, pre-dried at 120 ° C. for 10 minutes, peeled off, and fixed to a metal frame of an appropriate size with a heat-resistant adhesive tape. The film was dried at 200 ° C.
- a test piece having a width of 4 mm and a length of 21 mm was cut out from the obtained dry film, and measured at a measurement length of 15 mm, using a dynamic viscoelasticity measuring device (DVA-220 manufactured by IT Measurement Control Co., Ltd.), 110 Hz, heating rate.
- the storage elastic modulus (E ′) was measured in the range from room temperature to 450 ° C. under the condition of 4 ° C./min. At the refraction point of the storage elastic modulus (E ′) at this time, the temperature at the intersection of the extended line of the base line below the glass transition temperature and the tangent showing the maximum inclination above the refraction point was defined as the glass transition temperature.
- Average pore diameter A test piece was fixed on a measurement cell using a double-sided tape, platinum or gold was vacuum-deposited for several minutes, and SEM observation was performed at a magnification of 20,000 times.
- a polyvinylidene fluoride resin solution, alumina particles having an average particle diameter of 0.5 ⁇ m, and N-methyl-2-pyrrolidone were blended in a weight ratio of 14:19:67, respectively, and zirconium oxide beads (manufactured by Toray Industries, Inc., “Traceram”) (Registered Trademark) beads, 0.5 mm in diameter) were placed in a polypropylene container and dispersed with a paint shaker (manufactured by Toyo Seiki Seisakusho) for 6 hours. Subsequently, it filtered with the filter of 5 micrometers of filtration limits, and prepared the varnish.
- a paint shaker manufactured by Toyo Seiki Seisakusho
- the fluororesin concentration in the solution component was 2.1%, and the weight ratio of the fluororesin (solid content) to the particles was 8:92.
- the varnish was applied to the porous membrane A (polyethylene porous film, thickness 16 ⁇ m, porosity 38%, average pore diameter 0.15 ⁇ m, air resistance 280 sec / 100 ccAir) by a blade coating method at a temperature of 25 ° C.
- a humidity control zone having an absolute humidity of 9.2 g / m 3 was passed in 20 seconds.
- the porous membrane B was formed by immersing in an aqueous solution containing 5% by weight of N-methyl-2-pyrrolidone for 10 seconds, and further washed with pure water. Finally, it was dried by passing through a hot air drying oven at 70 ° C. to obtain a battery separator having a final thickness of 18.5 ⁇ m.
- a battery separator was obtained in the same manner as in Example 1 except that the blending ratio of the fluororesin solution, alumina particles and N-methyl-2-pyrrolidone used in Example 1 was 16:19:65.
- Example 3 A battery separator was obtained in the same manner as in Example 1 except that the blending ratio of the fluororesin solution, alumina particles and N-methyl-2-pyrrolidone used in Example 1 was 10:14:76.
- Example 4 A battery separator was obtained in the same manner as in Example 1 except that the alumina particles were replaced with titanium oxide particles (manufactured by Titanium Industry Co., Ltd., trade name “KR-380”, average particle size 0.38 ⁇ m).
- Example 5 A battery separator was obtained in the same manner as in Example 1 except that the alumina particles were replaced with spherical silica particles (manufactured by Sakai Chemical Industry Co., Ltd., average particle size: 1.0 ⁇ m).
- Example 6 Example 1 except that the alumina particles were changed to polymethyl methacrylate-based crosslinked particles (“Eposter” (registered trademark) MA, type 1002, manufactured by Nippon Shokubai Co., Ltd., average particle size 2.5 ⁇ m). Thus, a battery separator was obtained.
- Example 7 Battery separator as in Example 1, except that a porous film made of polyethylene having a thickness of 20 ⁇ m, a porosity of 45%, an average pore diameter of 0.17 ⁇ m, and an average air permeability of 240 sec / 100 ccAir was used as the porous membrane A Got.
- Example 8 A battery separator was obtained in the same manner as in Example 1 except that the blending ratio of the fluororesin solution, alumina particles, and N-methyl-2-pyrrolidone used in Example 1 was changed to 11:38:51.
- Example 9 A battery separator was obtained in the same manner as in Example 1 except that the blending ratio of the fluororesin solution, alumina particles and N-methyl-2-pyrrolidone used in Example 1 was 16: 9: 75.
- Example 10 A battery separator was obtained in the same manner as in Example 1 except that the absolute humidity of the humidity control zone was changed from 9.2 g / m 3 to 5.2 g / m 3 .
- Example 11 A battery separator was obtained in the same manner as in Example 1 except that the amount of varnish applied was adjusted to a final thickness of 19.5 ⁇ m.
- Example 12 A battery separator was obtained in the same manner as in Example 1 except that the amount of varnish applied was adjusted to a final thickness of 17.5 ⁇ m.
- Example 13 Example 1 except that a polyethylene porous film having a thickness of 7 ⁇ m, a porosity of 45%, an average pore diameter of 0.14 ⁇ m, and an average air resistance of 130 sec / 100 ccAir was used as the porous membrane A, and the final thickness was 9.5 ⁇ m.
- a battery separator was obtained.
- a battery separator was obtained in the same manner as in Example 1 except that the blending ratio of the fluororesin solution, alumina particles, and N-methyl-2-pyrrolidone used in Example 1 was 4: 5: 91.
- Example 2 A battery separator was obtained in the same manner as in Example 1 except that the blending ratio of the fluororesin solution, alumina particles, and N-methyl-2-pyrrolidone used in Example 1 was set to 26:31:43.
- Example 3 A battery separator was obtained in the same manner as in Example 1 except that the blending ratio of the fluororesin solution and N-methyl-2-pyrrolidone used in Example 1 was 18:82 and no alumina particles were added.
- the concentration of the fluororesin in the solution component was 2.2%.
- Comparative Example 4 A battery separator was obtained in the same manner as in Example 1 except that the absolute humidity of the humidity control zone was changed from 9.2 g / m 3 to 18.0 g / m 3 .
- Comparative Example 5 A battery separator was prepared in the same manner as in Example 1, except that the alumina particles used in Example 1 were changed to alumina particles having an average particle diameter of 13 nm (0.013 ⁇ m) (Aerosil Aluminum Oxide C: manufactured by Nippon Aerosil Co., Ltd.). Obtained.
- Comparative Example 6 A battery separator was obtained in the same manner as in Example 1 except that the blending ratio of the fluororesin solution, alumina particles, and N-methyl-2-pyrrolidone used in Example 1 was 18: 3: 79.
- the concentration of the polyamideimide resin in the solution component was 2.2%, and the weight ratio of the fluororesin (solid content) to the particles was 42:58.
- Table 1 shows the manufacturing conditions of the battery separators of Examples 1 to 13 and Comparative Examples 1 to 6, and the characteristics of the porous membrane A and the battery separator.
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Abstract
Description
ポリオレフィン系樹脂からなる多孔質膜Aにフッ素系樹脂と無機粒子または架橋高分子粒子を含む多孔質膜Bが積層された電池用セパレータであって、該粒子の含有量は多孔質膜Bの80重量%以上、97重量%以下、且つ、平均粒径は多孔質膜Aの平均孔径の1.5倍以上、50倍未満であり、式1および式2を満足する電池用セパレータ、である。
absT(1200):多孔質膜Bを多孔質膜Aから剥離した時の赤外線分光測定(透過法)による1200cm-1付近にピークを有する吸収の多孔質膜Aの厚さ10μm当たりの吸光度
0.001≦absR(1200)≦0.030・・・式2
absR(1200):多孔質膜Aの多孔質膜Bとは反対側の面の赤外線分光測定(反射法)による1200cm-1付近最大ピークの吸光度
本発明の電池用セパレータの製造方法は、以下の構成を有する。すなわち、
以下の工程(i)及び(ii)を含む上記電池用セパレータの製造方法、である。
フッ素系樹脂は、フッ化ビニリデン単独重合体、フッ化ビニリデン/フッ化オレフィン共重合体、フッ化ビニル単独重合体、及びフッ化ビニル/フッ化オレフィン共重合体からなる群より選ばれる1種以上を使用することが好ましい。特に好ましいものはポリテトラフルオロエチレンである。これらの重合体は、非水電解液とも親和性が高く、しかも耐熱性が適切で、非水電解液に対する化学的、物理的な安定性が高いため、高温下での使用にも電解液との親和性を十分維持できる。
工程(ii):工程(i)で得られたフッ素系樹脂膜が積層された複合膜を凝固浴に浸漬させてフッ素系樹脂膜を多孔質膜Bに変換させ、洗浄、乾燥し、電池用セパレータを得る工程。
(1)absT(1200)の測定
実施例および比較例で得られた電池用セパレータについて、多孔質膜Bを粘着テープで完全に剥がし取り、試料に供した。作製した試料を下記条件の透過法により赤外吸収スペクトルを得た。ブランク試料として未塗工の多孔質膜Aについても前記と同様にして測定した。フッ素系樹脂成分由来の1,200cm-1付近の吸光度(absT(1200))は1,200±20cm-1の領域に吸収極大をもつ吸収ピーク高さの値を求め、多孔質膜Aの膜厚10μm当たりの吸光度に換算した。
(測定条件)
装置:フーリエ変換赤外分光光度計FT-720(堀場製作所製)
検出器:DLATGS
分解能:4cm-1
積算回数:100回
(2)absR(1200)の測定
実施例および比較例で得られた電池用セパレータについて、非塗工面側(多孔質膜Aの多孔質膜Bが塗工された面とは反対側の面)を反射法を用いて赤外吸収スペクトルを得た。測定する面以外は前記(1)absT(1200)の測定で用いた装置および測定方法と同様にして赤外吸収スペクトルを得、フッ素系樹脂成分由来の1,200cm-1付近の吸光度(absR(1200))は1,200±20cm-1の領域に吸収極大をもつ吸収ピーク高さの値から求めた。
(3)膜厚
多孔質膜A及び電池用セパレータの膜厚は、接触式膜厚計(ソニーマニュファクチュアリング社製デジタルマイクロメーターM-30)を使用して測定した。多孔質膜Aの膜厚は、電池用セパレータから多孔質膜Bを剥がし取った試料に基づいて評価した。多孔質膜Bの膜厚は、電池用セパレータの膜厚と多孔質膜Aの膜厚の差から評価した。
(4)空孔率
10cm角の試料を用意し、その試料体積(cm3)と質量(g)を測定し、得られた結果から次式を用いて空孔率(%)を計算した。
なお、試料体積(cm3)は、10cm×10cm×厚み(cm)で求める。
(5)多孔質膜Bの密着性(剥離強度)
実施例及び比較例で得られた電池用セパレータの多孔質膜B面に粘着テープ(ニチバン(株)製、405番;24mm幅)を貼り、幅24mm、長さ150mmに裁断し、試験用サンプルを作製した。23℃、50%RH条件下で引張り試験機[(株)エー・アンド・デイ製「テンシロンRTM-100]を用いて、ピール法(剥離速度500mm/分、T型剥離)にて多孔質膜Aと多孔質膜Bとの界面の剥離強度を測定した。測定開始から測定終了までの100mmの間において、連続的に測定し、測定値の平均値を算出し、巾25mm換算して剥離強度とした。
(6)透気抵抗度上昇率
テスター産業(株)社製のガーレー式デンソメーターB型を使用して、電池用セパレータ又は多孔質膜Aをクランピングプレートとアダプタープレートの間にシワが入らないように固定し、JISP 8117に従って測定した。任意の3カ所を測定しその平均値を透気抵抗度とした。各実施例比較例の多孔質膜Aのみの透気抵抗度および電池用セパレータの透気抵抗度を求め、次式より透気抵抗度上昇率を求めた。
(7)ガラス転移温度
フッ素系樹脂溶液、または電池用セパレータを良溶媒に漬けてフッ素系樹脂のみを溶解させた樹脂溶液を、アプリケーターによってPETフィルム(東洋紡(株)製E5001)あるいはポリプロピレンフィルム(東洋紡(株)製パイレン(登録商標)-OT)に適当なギャップで塗布し、120℃10分間予備乾燥した後に剥離して、適当な大きさの金枠に耐熱粘着テープで固定した状態で、さらに真空下で200℃12時間乾燥し、乾式フィルムを得た。得られた乾式フィルムから幅4mm×長さ21mmの試験片を切り取り、測定長15mmで動的粘弾性測定装置(アイティー計測制御(株)製DVA―220)を用いて、110Hz、昇温速度4℃/分の条件下で室温から450℃までの範囲で貯蔵弾性率(E′)を測定した。この時の貯蔵弾性率(E′)の屈折点において、ガラス転移温度以下のベースラインの延長線と、屈折点以上における最大傾斜を示す接線との交点の温度をガラス転移温度とした。
(8)平均孔径
試験片を測定用セルに上に両面テープを用いて固定し、プラチナまたは金を数分間真空蒸着させ、倍率20,000倍でSEM観察をおこなった。
(9)粒子の平均粒径
平均粒径レーザ回折・散乱式粒度分布測定機(マイクロトラックHRA:リーズ&ノースラップ社製)を用いて、イオン交換水中に粒子のエチレングリコールスラリーを適切な濃度になるまで加え、粒度分布を測定する。粒子の手段の全体積を100%として累積カーブを求めたとき、その累積カーブが50%となる点の粒径を平均粒径(μm)とした。
(10)電解液浸透性
水平に置かれた平滑なガラス板上に白色紙(PPC タイプH(伊藤忠紙パルプ(株)製))を置き、その上に実施例および比較例で得られた電池用セパレータの多孔質膜Bの面を下にして重ね合わせた。次いで、上から(多孔質膜A側から)ポリカーボネート試薬100μLを液がほぼ円形になるように滴下した。滴下後3秒後に前記白色紙から電池用セパレータを剥がし、白色紙に染みこんだポリカーボネート試薬によるシミの大きさ(長径)を読み取った。この操作を3回繰り返して平均値(BL)を求めた。多孔質膜Aのみについても同様に測定した(AL)。BL-ALから電解液浸透性(L)を評価した。
値が大きいほど電解液浸透性が優れていることを意味する。
判定
L≧5mm ・・・・excellent
5mm>L≧3mm ・・・・good
3mm>L≧0mm ・・・・bad
(11)カール性(ソリ)の評価
実施例および比較例で得られた電池用セパレータを幅方向100mm×長手方向300mmの大きさに切り取り、除電ブラシで十分除電した後、多孔質膜Bを上にして水平に置かれたガラス板上に置いた。次いで、幅方向の両端10mmを固定し、長手方向端部の浮き上がり高さを両端部についてそれぞれ測定し、平均値を求めた。
〔実施例1〕
(フッ素系樹脂の合成)
フッ素系樹脂溶液として、KFポリマー#1120(呉羽化学工業(株)製ポリフッ化ビニリデン樹脂溶液(融点175℃、12%N-メチルピロリドン溶液))を用いた。
〔実施例2〕
実施例1で用いたフッ素樹脂溶液とアルミナ粒子とN-メチル-2-ピロリドンの配合比を16:19:65とした以外は実施例1と同様にして電池用セパレータを得た。
〔実施例3〕
実施例1で用いたフッ素樹脂溶液とアルミナ粒子とN-メチル-2-ピロリドンの配合比を10:14:76とした以外は実施例1と同様にして電池用セパレータを得た。
〔実施例4〕
アルミナ粒子を酸化チタン粒子(チタン工業(株)製、商品名「KR-380」、平均粒子径0.38μm)に替えた以外は実施例1と同様にして電池用セパレータを得た。
〔実施例5〕
アルミナ粒子を球状シリカ粒子(堺化学工業(株)製、平均粒子径1.0μm)に替えた以外は実施例1と同様にして電池用セパレータを得た。
〔実施例6〕
アルミナ粒子をポリメタクリル酸メチル系架橋物粒子(“エポスター”(登録商標)MA、タイプ1002、(株)日本触媒社製、平均粒子径2.5μm)に替えた以外は実施例1と同様にして電池用セパレータを得た。
〔実施例7〕
多孔質膜Aとして厚み20μm、空孔率45%、平均孔径0.17μm、平均透気抵抗度240sec/100ccAir、のポリエチレン製多孔質フィルムを用いた以外は実施例1と同様にして電池用セパレータを得た。
〔実施例8〕
実施例1で用いたフッ素樹脂溶液、アルミナ粒子、N-メチル-2-ピロリドンの配合比を11:38:51とした以外は実施例1と同様にして電池用セパレータを得た。
〔実施例9〕
実施例1で用いたフッ素樹脂溶液、アルミナ粒子、N-メチル-2-ピロリドンの配合比を16:9:75とした以外は実施例1と同様にして電池用セパレータを得た。
〔実施例10〕
調湿ゾーンの絶対湿度を9.2g/m3から5.2g/m3に変更した以外は実施例1と同様にして電池用セパレータを得た。
〔実施例11〕
ワニスの塗布量を調整し、最終厚み19.5μmとした以外は実施例1と同様にして電池用セパレータを得た。
〔実施例12〕
ワニスの塗布量を調整し、最終厚み17.5μmとした以外は実施例1と同様にして電池用セパレータを得た。
〔実施例13〕
多孔質膜Aとして厚み7μm、空孔率45%、平均孔径0.14μm、平均透気抵抗度130sec/100ccAir、のポリエチレン製多孔質フィルムを用い、最終厚み9.5μmとした以外は実施例1と同様にして電池用セパレータを得た。
〔比較例1〕
実施例1で用いたフッ素樹脂溶液、アルミナ粒子、N-メチル-2-ピロリドンの配合比を4:5:91とした以外は実施例1と同様にして電池用セパレータを得た。
〔比較例2〕
実施例1で用いたフッ素樹脂溶液、アルミナ粒子、N-メチル-2-ピロリドンの配合比を26:31:43とした以外は実施例1と同様にして電池用セパレータを得た。
〔比較例3〕
実施例1で用いたフッ素樹脂溶液、N-メチル-2-ピロリドンの配合比を18:82とし、アルミナ粒子を添加しなかった以外は実施例1と同様にして電池用セパレータを得た。
〔比較例4〕
調湿ゾーンの絶対湿度を9.2g/m3から18.0g/m3に変更した以外は実施例1と同様にして電池用セパレータを得た。
〔比較例5〕
実施例1で用いたアルミナ粒子を平均粒径13nm(0.013μm)アルミナ微粉末(アエロジルAluminum Oxide C:日本アエロジル(株)製)に変更した以外は実施例1と同様にして電池用セパレータを得た。
〔比較例6〕
実施例1で用いたフッ素樹脂溶液、アルミナ粒子、N-メチル-2-ピロリドンの配合比を18:3:79とした以外は実施例1と同様にして電池用セパレータを得た。
Claims (4)
- ポリオレフィン系樹脂からなる多孔質膜Aにフッ素系樹脂と無機粒子または架橋高分子粒子を含む多孔質膜Bが積層された電池用セパレータであって、該粒子の含有量は多孔質膜Bの80重量%以上、97重量%以下、且つ、平均粒径は多孔質膜Aの平均孔径の1.5倍以上、50倍未満であり、式1および式2を満足する電池用セパレータ。
0.01≦absT(1200)≦0.30・・・式1
absT(1200):多孔質膜Bを多孔質膜Aから剥離した時の赤外線分光測定(透過法)による1,200cm-1付近にピークを有する吸収の多孔質膜Aの厚さ10μm当たりの吸光度
0.001≦absR(1200)≦0.030・・・式2
absR(1200):多孔質膜Aの多孔質膜Bとは反対側の面の赤外線分光測定(反射法)による1,200cm-1付近最大ピークの吸光度 - 無機粒子がシリカ、二酸化チタン、アルミナから選ばれる少なくとも一種である請求項1記載の電池用セパレータ。
- 架橋高分子粒子が架橋ポリスチレン粒子、架橋アクリル系樹脂粒子、架橋メタクリル酸メチル系粒子ら選ばれる少なくとも一種である請求項1記載の電池用セパレータ。
- 以下の工程(i)及び(ii)を含む請求項1~3のいずれかに記載の電池用セパレータの製造方法。
工程(i):ポリオレフィン系樹脂からなる多孔質膜A上にフッ素系樹脂と無機粒子または架橋高分子粒子を含み、且つフッ素系樹脂の溶液成分中の濃度が1重量%以上、3.5重量%以下である塗工液(ワニス)を塗布した後、絶対湿度5g/m3以上、絶対湿度10g/m3未満の調湿ゾーンを3秒以上、30秒未満通過させて多孔質膜A上にフッ素系樹脂膜を形成する工程。
工程(ii):工程(i)で得られたフッ素系樹脂膜が積層された複合膜を凝固浴に浸漬させてフッ素系樹脂膜を多孔質膜Bに変換させ、洗浄、乾燥し、電池用セパレータを得る工程。
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WO2015146579A1 (ja) * | 2014-03-26 | 2015-10-01 | 東レバッテリーセパレータフィルム株式会社 | ポリオレフィン製積層多孔質膜、それを用いた電池用セパレータおよびポリオレフィン製積層多孔質膜の製造方法 |
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Also Published As
Publication number | Publication date |
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EP2736095A1 (en) | 2014-05-28 |
EP2736095A4 (en) | 2014-09-10 |
US10056595B2 (en) | 2018-08-21 |
KR101423103B1 (ko) | 2014-07-25 |
EP2736095B1 (en) | 2016-03-23 |
US20150030905A1 (en) | 2015-01-29 |
JP5412009B1 (ja) | 2014-02-12 |
CN103843173B (zh) | 2015-05-13 |
KR20140049091A (ko) | 2014-04-24 |
CN103843173A (zh) | 2014-06-04 |
JPWO2013153954A1 (ja) | 2015-12-17 |
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