WO2011013604A1 - 二次電池用多孔膜及び二次電池 - Google Patents
二次電池用多孔膜及び二次電池 Download PDFInfo
- Publication number
- WO2011013604A1 WO2011013604A1 PCT/JP2010/062499 JP2010062499W WO2011013604A1 WO 2011013604 A1 WO2011013604 A1 WO 2011013604A1 JP 2010062499 W JP2010062499 W JP 2010062499W WO 2011013604 A1 WO2011013604 A1 WO 2011013604A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- secondary battery
- segment
- porous film
- polymer
- electrode
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/443—Particulate material
-
- 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
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- 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
-
- 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
-
- 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
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Definitions
- the present invention relates to a porous membrane for a secondary battery, and more particularly to a porous membrane for a secondary battery having high output characteristics and long-term cycle characteristics used for a lithium ion secondary battery or the like.
- the present invention also relates to a slurry and a production method for obtaining such a porous membrane for a secondary battery, a secondary battery having such a porous membrane for a secondary battery, and other applications.
- Lithium ion secondary batteries show the highest energy density among practical batteries, and are widely used especially for small electronics. In addition, expansion to automobile applications is also expected, and there is a demand for higher capacity, longer life and further improvement in safety.
- an organic separator made of polyolefin such as polyethylene or polypropylene is used in a lithium ion secondary battery. Since the organic separator of polyolefin has a physical property of melting at 200 ° C. or lower, when the battery becomes hot due to internal and / or external stimulation, volume change such as shrinkage and melting occurs. There is a risk of explosion due to short circuit of the negative electrode or release of electrical energy.
- Patent Document 1 discloses a porous protection formed by using a slurry containing fine particles such as alumina, silica, and polyethylene resin on an electrode and a binder having high electrolytic solution resistance such as polyvinylidene fluoride. A membrane is disclosed. In the case of these porous film protective films, even if thermal contraction of the organic separator occurs at, for example, 150 ° C. or higher, the presence of fine particles on the electrode reduces the internal short circuit rate and improves safety.
- Patent Document 2 discloses a porous film in which fine particles such as alumina or an organic compound and a binder such as a styrene-butadiene copolymer are formed on a liner having releasability. Yes.
- a porous film in which fine particles such as alumina or an organic compound and a binder such as a styrene-butadiene copolymer are formed on a liner having releasability.
- an object of the present invention to provide a porous film used in a lithium ion secondary battery or the like having further improved output characteristics and long-term cycle characteristics, a slurry and a production method for obtaining such a porous film, and output characteristics and long-term performance.
- An object of the present invention is to provide a lithium ion secondary battery and its constituent elements having further improved cycle characteristics.
- the present inventors have included non-conductive particles such as inorganic particles in the porous film and non-conductive by using a block polymer as a binder (binder). It has been found that the dispersibility is improved due to the high adsorption stability to the conductive particles, and that the porous membrane has an appropriate electrolyte solution retaining property, so that the output characteristics of the secondary battery having the porous membrane are improved. Furthermore, it has been found that the porous membrane has high electrolyte impregnation property / electrolytic solution retention property for a long period of time, so that the long-term cycle characteristics are improved in addition to the high output characteristics, and the present invention has been completed.
- the present invention for solving the above-mentioned problems includes the following matters as a gist.
- the block polymer has two segments which are a segment showing compatibility with a secondary battery electrolyte containing ethylene carbonate and diethyl carbonate and a segment showing no compatibility with the secondary battery electrolyte.
- the porous membrane for a secondary battery as described in (1).
- (3) The porous membrane for a secondary battery according to any one of (1) to (2), wherein the block polymer has a weight average molecular weight in the range of 1,000 to 500,000.
- the block polymer has a segment showing compatibility with the electrolyte solution for secondary battery, and the segment showing compatibility with the electrolyte solution for secondary battery has a solubility parameter (SP) of 8.0 or more.
- SP solubility parameter
- the block polymer has a segment that does not show compatibility with the electrolyte solution for secondary battery, and the segment that does not show compatibility with the electrolyte solution for secondary battery has a solubility parameter of less than 8.0 or
- the porous membrane for a secondary battery according to any one of (1) to (4), comprising a monomer component having 11 or more and / or a monomer component having a hydrophobic portion.
- a method for producing a porous film for a secondary battery comprising a step of applying the slurry for a secondary battery porous film according to claim 7 to a substrate and then drying.
- a current collector an electrode mixture layer including a binder and an electrode active material provided on the current collector, and (1) to (6) provided on the electrode mixture layer
- a secondary battery electrode comprising the layer of the porous film for a secondary battery according to any one of the above.
- An organic separator layer, a secondary battery separator comprising the porous membrane for a secondary battery according to any one of (1) to (6) provided on the organic separator layer.
- a secondary battery including a positive electrode, a negative electrode, a separator, and an electrolyte for a secondary battery containing ethylene carbonate and diethyl carbonate, wherein at least one of the positive electrode, the negative electrode, and the separator is any of (1) to (6 A secondary battery comprising the porous film for a secondary battery according to any one of the above.
- the porous film contains a specific binder
- high dispersibility of non-conductive particles and high electrolyte solution retention in the porous film are achieved.
- electrode or separator of the present invention its output characteristics and long-term cycle characteristics are further improved. According to the production method and the slurry for a secondary battery porous membrane of the present invention, such a porous membrane for a secondary battery can be easily formed.
- the porous membrane for a secondary battery of the present invention includes non-conductive particles and a block polymer.
- Non-conductive particles It is desired that the non-conductive particles used in the present invention are stably present in a use environment such as a lithium ion secondary battery or a nickel hydride secondary battery, and are electrochemically stable.
- a use environment such as a lithium ion secondary battery or a nickel hydride secondary battery
- various inorganic particles and organic particles can be used.
- Organic particles are preferable from the viewpoint of producing particles with low metal contamination that adversely affect battery performance at low cost.
- inorganic particles include oxide particles such as aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, BaTiO 2 , ZrO, and alumina-silica composite oxide; nitride particles such as aluminum nitride and boron nitride; silicon, diamond, and the like Covalent crystal particles; poorly soluble ion crystal particles such as barium sulfate, calcium fluoride, and barium fluoride; clay fine particles such as talc and montmorillonite are used. These particles may be subjected to element substitution, surface treatment, solid solution, or the like, if necessary, or may be a single or a combination of two or more. Among these, oxide particles are preferable from the viewpoints of stability in an electrolytic solution and potential stability.
- the organic particles particles made of various polymer compounds such as polystyrene, polyethylene, polyimide, melamine resin, and phenol resin are used.
- the polymer compound forming the particles can be used as a mixture, a modified product, a derivative, a random copolymer, an alternating copolymer, a graft copolymer, a block copolymer, a crosslinked product, and the like.
- the polymer compound that forms the organic particles may be a mixture of two or more polymer compounds.
- conductive metal such as carbon black, graphite, SnO 2 , ITO, metal powder and fine powders of conductive compounds and oxides
- electrical insulation is achieved. It is also possible to use it with a certain character.
- These non-electrically conductive particles may be used in combination of two or more.
- non-conductive particles having a metal foreign matter content of 100 ppm or less.
- the metal foreign matter or metal ion is eluted, which causes ionic crosslinking with the polymer in the slurry for porous film, There is a possibility that the slurry for the porous film aggregates and as a result, the porosity of the porous film decreases and the output characteristics deteriorate.
- the metal it is most preferable to contain Fe, Ni, Cr and the like which are particularly easily ionized.
- the metal content in the non-conductive particles is preferably 100 ppm or less, more preferably 50 ppm or less.
- the term “metal foreign matter” as used herein means a simple metal other than non-conductive particles.
- the content of the metal foreign matter in the non-conductive particles can be measured using ICP (Inductively Coupled Plasma).
- ICP Inductively Coupled Plasma
- the minimum of content of a metal foreign material is not specifically limited, Preferably it is 0 ppm.
- the average particle size (volume average D50 average particle size) of the non-conductive particles used in the present invention is preferably 5 nm or more and 10 ⁇ m or less, more preferably 10 nm or more and 5 ⁇ m or less.
- the average particle diameter of the non-conductive particles be in the range of 50 nm or more and 2 ⁇ m or less because the dispersion, the ease of coating, and the controllability of voids are excellent.
- the BET specific surface area of these particles is specifically 0.9 to 200 m 2 / g from the viewpoint of suppressing the aggregation of the particles and optimizing the fluidity of the slurry for a porous film described later. Preferably, it is 1.5 to 150 m 2 / g.
- the non-conductive particles are organic particles
- the organic fine particles preferably have high heat resistance from the viewpoint of imparting heat resistance to the porous film and improving the stability of the battery.
- the temperature at which the weight is reduced by 10% by weight when heated at a heating rate of 10 ° C./min in thermobalance analysis is preferably 250 ° C. or higher, more preferably 300 ° C. or higher, and even more preferably 350 ° C. or higher. is there.
- the upper limit of the temperature is not particularly limited, but can be, for example, 450 ° C. or less.
- the lower limit of the particle size distribution (CV value) of the non-conductive particles is preferably 0.5% or more, and the upper limit is preferably 40% or less, more preferably 30% or less, and even more preferably 20 % Or less. By setting it within the range, it is possible to suppress the increase in resistance by inhibiting the movement of lithium without filling the voids of the non-conductive particle layer.
- the shape of the non-conductive powder used in the present invention is not particularly limited, such as a spherical shape, a needle shape, a rod shape, a spindle shape, and a plate shape, but a spherical shape, a needle shape, and a spindle shape are preferable.
- porous particles can also be used as the non-conductive particles.
- the content of non-conductive particles in the porous film is preferably 5 to 99% by weight, more preferably 50 to 98% by weight. By setting the content of non-conductive particles in the porous film within the above range, a porous film exhibiting high thermal stability and strength can be obtained.
- the block polymer used in the present invention is a block polymer having two types of segments. In addition to having these two types of segments, the block polymer may further have one or more other arbitrary segments.
- the two types of segments of the block polymer used in the present invention can be composed of various components, but the porous film can have electrolyte solution impregnation and electrolyte solution retention properties, and non-conductive particles.
- one of the two segments (referred to as “segment A” for convenience) has an electrolyte solution for secondary batteries containing ethylene carbonate and diethyl carbonate (hereinafter referred to as “the above-mentioned”). It is preferable that other segments (referred to as “segment B” for convenience) do not exhibit compatibility with the secondary battery electrolyte.
- a block polymer is comprised from the segment which shows compatibility with the said electrolyte solution for secondary batteries, and the segment which does not show compatibility with the said electrolyte solution for secondary batteries.
- a segment A which is substantially composed of a segment exhibiting compatibility with the electrolyte solution for secondary battery and a segment not exhibiting compatibility with the electrolyte solution for secondary battery. And what does not contain components other than segment B can be mentioned.
- That the segment is compatible with the secondary battery electrolyte means that the segment shows a certain extent in the secondary battery electrolyte, and the segment is incompatible with the secondary battery electrolyte. It can be judged by the degree of swelling.
- showing compatibility means that the degree of swelling of the segment with respect to the secondary battery electrolyte is 500% or more, or that the segment is dissolved in the secondary battery electrolyte.
- the segment does not exhibit compatibility with the electrolyte solution for secondary battery it means that the segment does not expand in the electrolyte solution, and the degree of swelling of the segment with respect to the electrolyte solution for secondary battery is 0. % Or more and 300% or less.
- the degree of swelling of each segment is measured by the following method.
- a polymer composed of the constituent components of segment A and a polymer composed of the constituent components of segment B are each formed into a film having a thickness of about 0.1 mm, cut into about 2 cm squares, and the weight (weight before immersion) is measured. .
- it is immersed in the electrolyte solution for secondary batteries at a temperature of 60 ° C. for 72 hours.
- the soaked film was pulled up and the weight immediately after the secondary battery electrolyte was wiped off (weight after soaking) was measured, and the value of (weight after soaking) / (weight before soaking) ⁇ 100 (%) was the degree of swelling.
- the solution obtained by dissolving LiPF 6 at a concentration of 1 mol / liter in a mixed solvent obtained by mixing in (1) is used.
- non-conductive particles can be highly dispersed in the solvent in the slurry for a porous film described later.
- a porous membrane comprising the block polymer having the above structure
- the porous membrane has a high electrolyte retention property for a long period of time, and further elution of metal ions and oligomer components from the porous membrane.
- the secondary battery having the porous film exhibits high long-term cycle characteristics.
- the sea-island structure is formed by the segment A and the segment B, and the porous film shows high lithium conductivity because it has an appropriate swelling property to the electrolyte, and the secondary battery having the porous film has high output characteristics. Show.
- the block polymer used in the present invention may be an AB block structure (AB type, ABA type, BAB type) composed only of the segment A and the segment B, or a structure containing other optional components.
- these optional components may be coordinated at the end of the AB block structure or may be coordinated in the AB block structure.
- the terminal structure is a component that is compatible with the electrolyte
- the porous membrane has high electrolyte impregnation and electrolyte retention
- the secondary battery having the porous membrane has a high long-term cycle. It is preferable because it shows characteristics.
- the segment A preferably includes a monomer component having a solubility parameter of 8.0 or more and less than 11 (cal / cm 3 ) 1/2 and / or a monomer component having a hydrophilic group.
- a monomer component having a solubility parameter of 8.0 or more and less than 11 (cal / cm 3 ) 1/2 and / or a monomer component having a hydrophilic group By including such a monomer component, the degree of swelling of the segment A with respect to the electrolytic solution can be controlled by the composition to provide a segment exhibiting compatibility with the electrolytic solution.
- the term “monomer” or “monomer component” is understood to be a monomer constituting a monomer composition or constitutes a polymer depending on the context. It is understood that it is a polymerized unit based on a monomer.
- Monomers having a solubility parameter of 8.0 or more and less than 11 include alkenes such as ethylene and propylene; carbon number of alkyl groups in esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and pentyl methacrylate. 1 to 5 methacrylic acid alkyl esters; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, etc. esters such as alkyl acrylates having 1-5 carbon atoms; butadiene, isoprene, etc.
- the alkyl group in the ester has an alkyl group of 1 to 5 carbonic acid alkyl ester or ester. More preferred are methacrylic acid alkyl esters in which the alkyl group has 1 to 5 carbon atoms.
- alkyl acrylate or alkyl methacrylate examples include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, and pentyl acrylate.
- Alkyl ester having 1 to 5 carbon atoms of alkyl group methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, and pentyl methacrylate Methacrylic acid alkyl ester having 1 to 5 carbon atoms in the alkyl group in the ester.
- the solubility parameter (SP) in the segment A is 8.0.
- the content of the monomer component that is less than 11 is preferably 30% by weight or more, and more preferably 50 to 90% by weight with respect to 100% by weight of the total amount of monomers used.
- the content of the monomer component having a solubility parameter (SP) in segment A of 8.0 or more and less than 11 can be controlled by the monomer charge ratio at the time of producing the block polymer.
- the solubility parameter (SP) is 8.0 or more and less than 11 and the content of the monomer component is within an appropriate range, so that it is compatible with the electrolyte solution but does not dissolve and elution inside the battery. Does not occur and exhibits high long-term cycle characteristics.
- the solubility parameter of the polymer can be determined according to the method described in Polymer Handbook, but those not described in this publication can be determined according to the “molecular attractive constant method” proposed by Small.
- the SP value ( ⁇ ) (cal / cm 3 ) 1 / is obtained from the characteristic value of the functional group (atomic group) constituting the compound molecule, that is, the statistics of the molecular attraction constant (G) and the molecular volume according to the following formula. This is a method for obtaining 2 .
- V Specific volume
- M Molecular weight d: Specific gravity
- the monomer component having a hydrophilic group includes a monomer having a —COOH group (carboxylic acid group), a monomer having an —OH group (hydroxyl group), and a —SO 3 H group (sulfonic acid group).
- Monomer having a monomer, a monomer having —PO 3 H 2 group, a monomer having —PO (OH) (OR) group (R represents a hydrocarbon group), and a lower polyoxyalkylene group The body is mentioned.
- Examples of the monomer having a carboxylic acid group include monocarboxylic acid and derivatives thereof, dicarboxylic acid, acid anhydrides thereof, and derivatives thereof.
- Examples of monocarboxylic acids include acrylic acid, methacrylic acid, and crotonic acid.
- Monocarboxylic acid derivatives include 2-ethylacrylic acid, 2-ethylacrylic acid, isocrotonic acid, ⁇ -acetoxyacrylic acid, ⁇ -trans-aryloxyacrylic acid, ⁇ -chloro- ⁇ -E-methoxyacrylic acid, ⁇ -Diaminoacrylic acid and the like.
- Examples of the dicarboxylic acid include maleic acid, fumaric acid, itaconic acid and the like.
- Examples of the acid anhydride of dicarboxylic acid include maleic anhydride, acrylic anhydride, methyl maleic anhydride, and dimethyl maleic anhydride.
- Dicarboxylic acid derivatives include methyl maleic acid, dimethyl maleic acid, phenyl maleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid and the like methyl allyl maleate, diphenyl maleate, nonyl maleate, decyl maleate, dodecyl maleate, And maleate esters such as octadecyl maleate and fluoroalkyl maleate.
- Examples of the monomer having a hydroxyl group include ethylenically unsaturated alcohols such as (meth) allyl alcohol, 3-buten-1-ol and 5-hexen-1-ol; 2-hydroxyethyl acrylate, acrylic acid-2 Ethylene such as hydroxypropyl, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, di-2-hydroxyethyl maleate, di-4-hydroxybutyl maleate, di-2-hydroxypropyl itaconate Alkanol esters of the unsaturated unsaturated carboxylic acid; general formula CH 2 ⁇ CR 1 —COO— (CnH 2 nO) m—H (m is an integer of 2 to 9, n is an integer of 2 to 4, and R 1 is hydrogen or An ester of a polyalkylene glycol represented by a methyl group) and (meth) acrylic acid; 2-hydroxy Mono (meth) acrylic acid esters of dihydroxy esters of dicarboxylic acids such as
- Examples of the monomer having a sulfonic acid group include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth) allyl sulfonic acid, styrene sulfonic acid, (meth) acrylic acid-2-ethyl sulfonate, 2-acrylamide-2. -Methylpropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid and the like.
- Monomers having a —PO 3 H 2 group and / or —PO (OH) (OR) group include 2- (meth) acryloyloxyethyl phosphate, methyl phosphate -2- (Meth) acryloyloxyethyl, ethyl phosphate- (meth) acryloyloxyethyl, and the like.
- Examples of the monomer containing a lower polyoxyalkylene group-containing group include poly (alkylene oxide) such as poly (ethylene oxide).
- segment A showing compatibility with the electrolytic solution is composed of those having the monomer component having the hydrophilic group, among these monomers having the hydrophilic group, dispersion of non-conductive particles From the viewpoint of further improving the properties, a monomer having a carboxylic acid group is preferred.
- the content of the monomer having a hydrophilic group in the segment A in the case where the segment A exhibiting compatibility with the electrolytic solution is composed of those having the monomer component having the hydrophilic group is determined as follows. It is preferably in the range of 0.5 to 40% by weight, more preferably 3 to 20% by weight, based on 100% by weight of the total amount of the monomer.
- the content of the monomer having a hydrophilic group in the segment A can be controlled by the monomer charging ratio at the time of producing the block polymer. When the content of the monomer having a hydrophilic group in segment A is within a predetermined range, swelling to an appropriate electrolytic solution is exhibited, and elution inside the battery does not occur.
- Segment A may have one of these monomer components alone, or may have two or more in combination.
- the segment B preferably includes a monomer component having a solubility parameter of less than 8.0 or 11 or more and / or a monomer component unit having a hydrophilic group.
- a monomer component having a solubility parameter of less than 8.0 or 11 or more and / or a monomer component unit having a hydrophilic group By including such a monomer component, the degree of swelling of the segment B with respect to the electrolytic solution can be controlled by the composition, so that the segment does not exhibit compatibility with the electrolytic solution.
- the segment B preferably includes a monomer component unit having a cross-linkable group described later.
- Monomer components having a solubility parameter of less than 8.0 or 11 or more include ⁇ , ⁇ -unsaturated nitrile compounds such as acrylonitrile and methacrylonitrile; fluoroalkyl acrylate, 2- (fluoroalkyl) methyl acrylate, Fluorine-containing acrylic acid ester such as 2- (fluoroalkyl) ethyl acrylate; Fluorine-containing fluorine alkyl such as fluoroalkyl methacrylate, 2- (fluoroalkyl) methyl methacrylate, 2- (fluoroalkyl) ethyl methacrylate Examples include acrylic acid esters.
- the segment B includes a monomer component having a solubility parameter (SP) of less than 8.0 or 11 or more
- the monomer component having a solubility parameter in the segment B of less than 8.0 or 11 or more The content is preferably in the range of 30% to 100% by weight, more preferably 50% to 100% by weight, based on 100% by weight of the total amount of monomers used.
- the content of the monomer component having a solubility parameter (SP) in segment B of less than 8.0 or 11 or more can be controlled by the monomer charge ratio at the time of producing the block polymer.
- Examples of monomer components having a hydrophobic portion include styrene, ⁇ -styrene, chlorostyrene, vinyl toluene, t-butyl styrene, vinyl benzoic acid, methyl vinyl benzoate, vinyl naphthalene, chloromethyl styrene, ⁇ -methyl styrene, Styrene monomers such as divinylbenzene; acrylic acid-hexyl, acrylic acid-heptyl, acrylic acid-octyl, acrylic acid-2-ethylhexyl, acrylic acid-nonyl, acrylic acid-decyl, acrylic acid-lauryl, acrylic acid-n -Acrylic acid alkyl ester having 6 or more carbon atoms in the ester such as tetradecyl, acrylic acid-stearyl, etc .; methacrylic acid-hexyl, methacrylic acid-heptyl, methacrylic acid-octy
- an acrylic group having 9 or more carbon atoms in the alkyl group in esters such as 2-ethylhexyl acrylate, acrylate-nonyl, acrylate-decyl, acrylate-lauryl, acrylate-n-tetradecyl, acrylate-stearyl, etc.
- esters such as acid alkyl esters, 2-ethylhexyl methacrylate, methacrylate-nonyl, methacrylate-decyl, methacrylate-lauryl, methacrylate-n-tetradecyl, methacrylate-stearyl
- the methacrylic acid alkyl ester is preferable because of its low compatibility with the electrolytic solution.
- the alkyl alkyl acrylate ester having 9 or more carbon atoms in the alkyl group Preferred are methacrylic acid alkyl ester ⁇ , ⁇ -unsaturated nitrile compounds and styrene monomers having an alkyl group with 9 or more carbon atoms, and since they do not show any swelling property to the electrolyte, ⁇ , ⁇ -unsaturated nitrile compounds and Styrene monomers are more preferred, and styrene monomers are most preferred.
- segment B is composed of a monomer component having a hydrophobic part
- the content of the monomer component having a hydrophobic part in segment B is preferably based on 100% by weight of the total amount of monomers used. Is 10% by weight or more and 100% by weight or less, more preferably 20% by weight or more and 100% by weight or less.
- the content of the monomer component having a hydrophobic portion in the segment B can be controlled by the monomer charging ratio at the time of producing the block polymer. When the content of the monomer component having a hydrophobic portion in the segment B is in the above range, higher electrolyte solution resistance and long-term cycle characteristics are exhibited.
- Segment B may have one of these monomer components alone, or may have two or more in combination.
- the content ratio of the crosslinkable group in the case where the segment B includes a monomer component unit having a crosslinkable group, which will be described later, in the segment contains the thermally crosslinkable crosslinkable group in the segment B during polymerization.
- the amount of monomer is preferably in the range of 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, with respect to 100% by weight of the total amount of monomers in segment B.
- the content ratio of the heat-crosslinkable crosslinkable group in the segment B can be controlled by the monomer charge ratio when the segment B in the block polymer is produced.
- the non-conductive particles can be highly dispersed in the solvent, and the secondary film having the porous film is further provided. In the battery, elution into the electrolyte can be suppressed, and excellent porous film strength and long-term cycle characteristics can be exhibited.
- the block polymer preferably contains a segment of a soft polymer having a glass transition temperature of 15 ° C. or lower.
- the block polymer contains a segment of a soft polymer having a glass transition temperature of 15 ° C. or lower means that the block polymer of the present invention contains a segment constituting a soft polymer having a glass transition temperature of 15 ° C. or lower. Means that. Specifically, since at least one of segment A and segment B is the same segment as the segment constituting the soft polymer having a glass transition temperature of 15 ° C. or lower, an electrode having high flexibility can be obtained. Is preferred.
- segment A when segment A shows compatibility with the electrolytic solution and segment B does not show compatibility with the electrolytic solution, segment A is the same segment as that constituting the soft polymer having a glass transition temperature of 15 ° C. or lower. Preferably, it is the same segment as the segment constituting the soft polymer having a glass transition temperature of ⁇ 5 ° C. or less, more preferably the segment constituting the soft polymer having a glass transition temperature of ⁇ 40 ° C. or less. Is the same segment. Since segment A is the same segment as that constituting the soft polymer having a glass transition temperature within the above range, the mobility of segment A can be achieved while segment B in the block polymer is adsorbed on the active material surface. Therefore, the lithium acceptability at low temperature is improved. In addition, the glass transition temperature of a segment can be adjusted by further combining the combination of the monomer illustrated above and the copolymerizable monomer mentioned later.
- the ratio of segment A to segment B in the block polymer is such that the composition has a high output characteristic while having a long cycle characteristic while controlling the degree of swelling of the block polymer into the electrolyte within a predetermined range, although it varies depending on the degree of cross-linking, the ratio of segment A to segment B is 10:90 to 90:10 (weight ratio), more preferably 30 when there is no copolymer component other than segment A and segment B. : 70 to 70:30 (weight ratio).
- segment A is a (meth) acrylic acid alkyl ester having 1 to 5 carbon atoms in the ester
- segment B is a combination of an ⁇ , ⁇ -unsaturated nitrile compound or a styrene monomer.
- the segment A is a (meth) acrylic acid alkyl ester having an alkyl group of 1 to 5 carbon atoms in the ester
- the segment B is most preferable because the combination of styrene monomers is excellent in dispersibility, load characteristics, and cycle characteristics. preferable.
- the degree of swelling of the block polymer with respect to the electrolytic solution tends to decrease as the molecular weight increases and increase as the molecular weight decreases. If the molecular weight is too small, dissolution in the electrolyte solution tends to occur. Accordingly, the range of the weight average molecular weight of the block polymer for achieving a suitable degree of swelling varies depending on the structure, the degree of crosslinking, and the like. For example, when there is no copolymer component other than segment A and segment B, tetrahydrofuran ( The standard polystyrene conversion value measured by gel permeation chromatography using THF as a developing solvent is 1,000 to 500,000, more preferably 5,000 to 100,000. When the weight average molecular weight of the block polymer is within the above range, the adsorption stability of the polymer to the non-conductive particles is high, and no bridging aggregation due to the polymer occurs, and excellent dispersibility is exhibited.
- the preferred range of degree of crosslinking is, for example, dissolved when immersed in a polar solvent such as tetrahydrofuran for 24 hours or 400% or more A degree of cross-linking that swells is preferred.
- the crosslinking method of the block polymer include a method of crosslinking by heating or energy ray irradiation. By using a block polymer that can be cross-linked by heating or energy ray irradiation, the degree of cross-linking can be adjusted by heating conditions or irradiation conditions (intensity, etc.) of energy ray irradiation.
- the degree of swelling tends to decrease as the degree of crosslinking increases, the degree of swelling can be adjusted by changing the degree of crosslinking.
- the method for preparing a block polymer that can be crosslinked by heating or irradiation with energy rays include a method of introducing a crosslinkable group into the block polymer and a method of using a crosslinking agent in combination.
- Examples of the method for introducing a crosslinkable group into the block polymer include a method for introducing a photocrosslinkable crosslinkable group into the block polymer and a method for introducing a heat crosslinkable crosslinkable group.
- the method of introducing a heat-crosslinkable crosslinkable group into the block polymer can crosslink the porous film by heat-treating the porous film after forming the porous film, and further dissolve in the electrolytic solution. It can be suppressed, and a tough and flexible porous membrane is obtained, which is preferable.
- the heat-crosslinkable crosslinkable group is at least one selected from the group consisting of an epoxy group, an N-methylolamide group, an oxetanyl group, and an oxazoline group. Species are preferred, and an epoxy group is more preferred in terms of easy crosslinking and adjustment of the crosslinking density.
- Examples of the monomer containing an epoxy group include a monomer containing a carbon-carbon double bond and an epoxy group, and a monomer containing a halogen atom and an epoxy group.
- Examples of the monomer containing a carbon-carbon double bond and an epoxy group include unsaturated glycidyl ethers such as vinyl glycidyl ether, allyl glycidyl ether, butenyl glycidyl ether, o-allylphenyl glycidyl ether; butadiene monoepoxide, Diene or polyene monoepoxides such as chloroprene monoepoxide, 4,5-epoxy-2-pentene, 3,4-epoxy-1-vinylcyclohexene, 1,2-epoxy-5,9-cyclododecadiene; Alkenyl epoxides such as epoxy-1-butene, 1,2-epoxy-5-hexene, 1,2-ep
- Examples of the monomer having a halogen atom and an epoxy group include epihalohydrins such as epichlorohydrin, epibromohydrin, epiiodohydrin, epifluorohydrin, ⁇ -methylepichlorohydrin; p-chlorostyrene oxide; dibromo Phenyl glycidyl ether;
- Examples of the monomer containing an N-methylolamide group include (meth) acrylamides having a methylol group such as N-methylol (meth) acrylamide.
- Monomers containing an oxetanyl group include 3-((meth) acryloyloxymethyl) oxetane, 3-((meth) acryloyloxymethyl) -2-trifluoromethyloxetane, and 3-((meth) acryloyloxymethyl). ) -2-phenyloxetane, 2-((meth) acryloyloxymethyl) oxetane, 2-((meth) acryloyloxymethyl) -4-trifluoromethyloxetane, and the like.
- Monomers containing an oxazoline group include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2- Examples thereof include oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline and the like.
- the content ratio of the heat-crosslinkable crosslinkable group in the block polymer is preferably 0.00 with respect to 100% by weight of the total amount of monomers as the amount of the monomer containing the heat-crosslinkable crosslinkable group at the time of polymerization. It is in the range of 1 to 10% by weight, more preferably 0.1 to 5% by weight.
- the content ratio of the heat-crosslinkable crosslinkable group in the block polymer can be controlled by the monomer charge ratio when producing the block polymer. When the content of the thermally crosslinkable crosslinking group in the block polymer is within the above range, elution into the electrolytic solution can be suppressed, and excellent porous film strength and long-term cycle characteristics can be exhibited.
- the heat-crosslinkable crosslinkable group is a monomer containing a heat-crosslinkable crosslinkable group in addition to the above-mentioned monomer, and / or other copolymerizable with these monomers. It can introduce
- the block polymer used in the present invention may contain a monomer copolymerizable with these in addition to the monomer component described above as a component other than the segment A and the segment B.
- Monomers copolymerizable with these include carboxylic acid esters having two or more carbon-carbon double bonds such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and trimethylolpropane triacrylate; vinyl chloride, vinylidene chloride Halogen atom-containing monomers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, and other vinyl ethers; methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone, isopropenyl vinyl ketone, and other vinyl ketones; And heterocyclic ring-containing vinyl compounds such as vinylpyrrolidone, vinylpyridine and vinylimidazole; and amide monomers such as acrylamide and N-methylol
- the block polymer used in the present invention is not particularly limited with respect to the polymerization method as long as a block polymer having segment A and segment B is obtained.
- the monomer A is polymerized by the living polymerization method, and then the monomer B is added and polymerized without stopping the growth terminal of the obtained polymer to obtain a block polymer. Can do.
- monomer A and monomer B are separately synthesized by a living polymerization method, and polymer A and polymer B are preferably functional groups at their ends so that they can react and bond at the ends. Is introduced. Thereafter, A and B are mixed to obtain a block polymer by coupling reaction, polyaddition and polycondensation.
- a method of interfacial polycondensation or solution polycondensation of acid chloride and amine a method of polycondensation of amine-terminated polyamide and carboxylic acid-terminated polyamide in a molten state, and the like can be mentioned.
- the monomer A is polymerized by a living polymerization method, and then a functional group is introduced into the living terminal to obtain a polymer A having a terminal functional group.
- a block polymer can be obtained by introducing a radical initiator into the obtained polymer A by a terminal group reaction and chain-polymerizing with the monomer B as a macroinitiator.
- a radical initiator into the obtained polymer A by a terminal group reaction and chain-polymerizing with the monomer B as a macroinitiator.
- a method of NCO conversion with an excess diisocyanate, t-butyl hydroperoxide bonded to the end, and then radical polymerization can be mentioned.
- Living polymerization methods include various polymerization methods such as living anion polymerization, living cation polymerization, living coordination polymerization, and living radical polymerization. By using such a polymerization method, various vinyl monomers can be polymerized. Among them, living radical polymerization is preferable from the viewpoint of controlling the molecular weight and structure of the block copolymer and copolymerizing a monomer having a crosslinkable functional group.
- Living polymerisation in the narrow sense, indicates that the terminal always has activity, but generally also includes pseudo-living polymerization where the terminal is inactive and the terminal is in equilibrium. It is.
- the living radical polymerization in the present invention is a radical polymerization in which the polymerization end is activated and the inactivation is maintained in an equilibrium state, and has been actively studied in various groups in recent years.
- Examples thereof include those using a chain transfer agent such as polysulfide, those using a cobalt porphyrin complex (Journal of American Chemical Society, 1994, 116, 7943) and radical scavengers such as nitroxide compounds (Macromolecules, 1994). 27, 7228), Inferter polymerization (Macromol. Chem. Rapid Commun., 3, 133 (1982)), which irradiates light on dithiocarbamate by Otsu et al.
- a chain transfer agent such as polysulfide
- those using a cobalt porphyrin complex Journal of American Chemical Society, 1994, 116, 7943
- radical scavengers such as nitroxide compounds
- RAFT atom transfer radical polymerization
- a compound having the ester) structure reversible addition elimination chain transfer is used as a chain transfer agent (Reversible Addition-Fragmentation Chain Transfer: RAFT) can be mentioned polymerizing the like.
- RAFT Reversible Addition-Fragmentation Chain Transfer
- a stable nitroxy radical compound is used as the radical scavenger.
- the stable nitroxy radical compound is not particularly limited, and includes known stable free radical agents, such as 2,2,5,5-substituted-1-pyrrolidinyloxy radicals, and other nitroxy groups derived from cyclic hydroxyamines. Free radicals are preferred.
- an alkyl group having 4 or less carbon atoms such as a methyl group or an ethyl group is suitable.
- nitroxy free radical compounds include, but are not limited to, 2,2,6,6-tetramethyl-1-piperidinyloxy radical (TEMPO), 2,2,6,6-tetraethyl-1- Piperidinyloxy radical, 2,2,6,6-tetramethyl-4-oxo-1-piperidinyloxy radical, 2,2,5,5-tetramethyl-1-pyrrolidinyloxy radical, 1, Examples include 1,3,3-tetramethyl-2-isoindolinyloxy radical, N, N-di-t-butylamineoxy radical, and the like. Of these, 2,2,6,6, -tetramethyl-1-piperidinyloxy and 4-oxo-2,2,6,6, -tetramethyl-1-piperidinyloxy are preferable. These may be used alone or in combination of two or more.
- TEMPO 2,2,6,6-tetramethyl-1-piperidinyloxy radical
- 2-piperidinyloxy radical 2,2,6,6-tetraethyl-1
- a radical generator When using the above stable nitroxy radical compound, a radical generator is usually used.
- the radical generator is not particularly limited as long as it generates radicals at the polymerization temperature, and a general thermal decomposition polymerization initiator can be used.
- a general thermal decomposition polymerization initiator can be used.
- azobisisobutyronitrile ( AIBN) azo compounds such as azobisisobutyric acid ester and hyponitrite
- benzoyl peroxide (BPO) benzoyl peroxide (BPO), lauroyl peroxide, dicumyl peroxide, dibenzoyl peroxide and the like. These may be used alone or in combination of two or more.
- an alkoxyamine compound may be used as an initiator.
- a terminal functional group can be introduced by using an alkoxyamine having a functional group in the alkoxy group.
- the polymerization is generally carried out at a polymerization temperature of about 50 to 170 ° C. A preferred temperature range is 70 to 160 ° C.
- the reaction pressure is usually carried out at normal pressure, but it can also be carried out under pressure.
- a chain transfer agent or terminator having a target functional group in the molecule is used as a method for introducing a functional group into the terminal of the polymerized vinyl copolymer.
- the method to use etc. are mentioned.
- the chain transfer agent or terminator having the functional group in the molecule is not particularly limited.
- a hydroxyl group is introduced by mercaptoethanol, mercaptopropanol, mercaptobutanol, 2,2′-dithioethanol, etc., and 2-mercaptoacetic acid is introduced.
- 2-mercaptopropionic acid, dithioglycolic acid, 3,3′-dithiopropionic acid, 2,2′-dithiobenzoic acid and the like introduce a carboxyl group
- 3-mercaptopropylmethyldimethoxysilane introduces a silyl group
- RAFT polymerization When reversible addition / elimination chain transfer polymerization (RAFT polymerization) is used as the living polymerization, a sulfur compound such as dithioester, trithiocarbamate, xanthate or dithiocarbamate is started as a chain transfer agent (and also serves as an initiator). Polymerization is performed as an agent.
- RAFT polymerization reversible addition / elimination chain transfer polymerization
- an additional radical initiator for polymerization particularly an initiator further comprising an azo or peroxo initiator that decomposes by heat to generate radicals.
- azo compounds such as azobisisobutyronitrile (AIBN), azobisisobutyric acid ester, hyponitrite; benzoyl peroxide (BPO), lauroyl peroxide, dicumyl peroxide, dibenzoyl peroxide, and the like. These may be used alone or in combination of two or more.
- the living polymerization in the present invention can be carried out by solvent polymerization (bulk polymerization), solution polymerization in an organic solvent (for example, toluene), emulsion polymerization or suspension polymerization.
- solvent polymerization bulk polymerization
- solution polymerization in an organic solvent for example, toluene
- emulsion polymerization emulsion polymerization or suspension polymerization.
- Each stage of the polymerization process can be performed in a “batch” process (ie, a discontinuous process) in the same reactor, or in a semi-continuous or continuous process in separate reactors.
- examples of the solvent used include, but are not limited to, the following solvents.
- hydrocarbon solvents such as hexane and octane
- ester solvents such as ethyl acetate and n-butyl acetate
- ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone
- alcohol solvents such as methanol, ethanol and isopropanol
- tetrahydrofuran, diethyl ether examples include ether solvents such as dioxane and ethylene glycol dimethyl ether; amide solvents such as dimethylformamide and dimethylacetamide; aromatic petroleum solvents such as toluene, xylene and benzene.
- the type and amount of the solvent used are the solubility of the monomer used, the solubility of the resulting polymer, the polymerization initiator concentration and monomer concentration appropriate for achieving a sufficient reaction rate, the solubility of the sulfur compound, It may be determined in consideration of the influence on human body and environment, availability, price, etc., and is not particularly limited. Among them, in terms of solubility, availability, and price, industrially, toluene, dimethylformamide, tetrahydrofuran, and acetone are preferable, and toluene and dimethylformamide are more preferable.
- the emulsifier used includes, but is not limited to, the following emulsifiers.
- Anionic surfactants such as sodium, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate; polyoxyethylene alkyl ether, polyoxyethylene higher alcohol ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, poly Oxyethylene sorbitol fatty acid ester,
- emulsifiers may be used alone or in combination. If necessary, a dispersant for suspension polymerization described later may be added.
- the amount of the emulsifier used is not particularly limited, but is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the monomer from the viewpoint that the emulsified state is good and the polymerization proceeds smoothly.
- anionic surfactants and nonionic surfactants are preferred from the viewpoint of stability in the emulsified state.
- any of the commonly used dispersants can be used as the dispersant.
- the following dispersants can be mentioned, but are not limited thereto.
- examples thereof include partially saponified polyvinyl acetate, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, gelatin, and polyalkylene oxide. These may be used alone or in combination.
- an emulsifier used in the emulsion polymerization may be used in combination.
- the amount of the dispersant to be used is not particularly limited, but is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the monomer used from the viewpoint that the polymerization proceeds smoothly.
- the block polymer used in the present invention is preferably obtained through a particulate metal removal step of removing particulate metal contained in the polymer solution or polymer dispersion in the production step of the block polymer.
- the method for removing the particulate metal component from the polymer solution or polymer dispersion in the particulate metal removal step is not particularly limited.
- Examples thereof include a removal method and a removal method using magnetic force.
- the removal object is a metal component
- the method of removing by magnetic force is preferable.
- the method for removing by magnetic force is not particularly limited as long as it is a method capable of removing a metal component. However, in consideration of productivity and removal efficiency, it is preferably performed by placing a magnetic filter in the block polymer production line. .
- the content of the block polymer in the porous membrane is preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight, and most preferably 0.5 to 3% by weight.
- the content ratio of the binder in the porous film is in the above range, the migration of lithium is inhibited while maintaining the binding property between the non-conductive particles and the binding property to the electrode or the separator. And it can suppress that resistance increases.
- the porous film may further contain an arbitrary component.
- optional components include components such as a dispersant, a leveling agent, an antioxidant, a binder other than the block polymer, a thickener, and an electrolytic solution additive having a function of inhibiting electrolytic decomposition. . These are not particularly limited as long as they do not affect the battery reaction.
- dispersant examples include anionic compounds, cationic compounds, nonionic compounds, and polymer compounds.
- a dispersing agent is selected according to the nonelectroconductive particle to be used.
- the content ratio of the dispersing agent in the porous film is preferably within a range that does not affect the battery characteristics, and specifically 10% by weight or less.
- leveling agent examples include surfactants such as alkyl surfactants, silicon surfactants, fluorine surfactants, and metal surfactants. By mixing the surfactant, it is possible to prevent the repelling that occurs during coating or to improve the smoothness of the electrode.
- antioxidants examples include a phenol compound, a hydroquinone compound, an organic phosphorus compound, a sulfur compound, a phenylenediamine compound, and a polymer type phenol compound.
- the polymer type phenol compound is a polymer having a phenol structure in the molecule, and a polymer type phenol compound having a weight average molecular weight of 200 to 1000, preferably 600 to 700 is preferably used.
- binder other than the block polymer examples include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyacrylic acid derivatives, polyacrylonitrile derivatives, and soft polymers used in the electrode binder described later. Can be used.
- PTFE polytetrafluoroethylene
- PVDF polyvinylidene fluoride
- polyacrylic acid derivatives polyacrylonitrile derivatives
- soft polymers used in the electrode binder described later examples include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyacrylic acid derivatives, polyacrylonitrile derivatives, and soft polymers used in the electrode binder described later. Can be used.
- thickeners include cellulose polymers such as carboxymethylcellulose, methylcellulose, hydroxypropylcellulose, and ammonium salts and alkali metal salts thereof; (modified) poly (meth) acrylic acid and ammonium salts and alkali metal salts thereof; Polyvinyl alcohols such as polyvinyl alcohol, acrylic acid or copolymers of acrylate and vinyl alcohol, maleic anhydride or copolymers of maleic acid or fumaric acid and vinyl alcohol; polyethylene glycol, polyethylene oxide, polyvinyl pyrrolidone, modified poly Acrylic acid, oxidized starch, phosphoric acid starch, casein, various modified starches, acrylonitrile-butadiene copolymer hydride, and the like.
- cellulose polymers such as carboxymethylcellulose, methylcellulose, hydroxypropylcellulose, and ammonium salts and alkali metal salts thereof
- Polyvinyl alcohols such as polyvinyl alcohol, acrylic acid or copolymers of acrylate and vinyl
- (modified) poly means “unmodified poly” or “modified poly”
- (meth) acryl means “acryl” or “methacryl”.
- vinylene carbonate used in the electrode mixture layer slurry and the electrolytic solution described later can be used.
- Other examples include nanoparticles such as fumed silica and fumed alumina: surfactants such as alkyl surfactants, silicon surfactants, fluorine surfactants, and metal surfactants.
- the preferred content ratio of the optional components in the porous film is preferably within a range that does not affect the battery characteristics. Specifically, each optional component is 10% by weight or less, and the total content of optional components is 20% by weight or less. It is.
- Method for producing porous membrane As a method for producing a porous membrane for a secondary battery of the present invention, 1) a method for applying a slurry for porous membrane containing non-conductive particles, a block polymer and a solvent on a predetermined substrate, followed by drying; 2) A method in which a substrate is dipped in a slurry for a porous film containing non-conductive particles, a block polymer and a solvent, and then dried; 3) A slurry for a porous film containing non-conductive particles, a block polymer and a solvent is removed from the release film. And a method of transferring the resulting porous film onto a predetermined substrate.
- 1) A method of applying a slurry for a porous film containing non-conductive particles, a block polymer and a solvent to a substrate and then drying is most preferable because the film thickness of the porous film can be easily controlled.
- the method for producing a porous membrane for a secondary battery according to the present invention is characterized in that the porous membrane slurry is applied to a substrate and then dried.
- the slurry for a secondary battery porous membrane of the present invention contains non-conductive particles, a block polymer, and a solvent.
- non-conductive particles and the block polymer are the same as those described for the porous membrane for a secondary battery.
- the solvent is not particularly limited as long as it can uniformly disperse the solid content (nonconductive particles and block polymer).
- the solvent used for the slurry for the porous membrane either water or an organic solvent can be used.
- organic solvents include cycloaliphatic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; ketones such as acetone, ethylmethylketone, diisopropylketone, cyclohexanone, methylcyclohexane, and ethylcyclohexane.
- Chlorinated aliphatic hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride; esters such as ethyl acetate, butyl acetate, ⁇ -butyrolactone, ⁇ -caprolactone; acylonitriles such as acetonitrile and propionitrile; tetrahydrofuran, ethylene Ethers such as glycol diethyl ether: Alcohols such as methanol, ethanol, isopropanol, ethylene glycol, ethylene glycol monomethyl ether; N-methyl Amides such as pyrrolidone and N, N-dimethylformamide are exemplified.
- solvents may be used alone, or two or more of these may be mixed and used as a mixed solvent.
- a solvent having excellent dispersibility of non-conductive particles and having a low boiling point and high volatility is preferable because it can be removed in a short time and at a low temperature.
- acetone, toluene, cyclohexanone, cyclopentane, tetrahydrofuran, cyclohexane, xylene, water, N-methylpyrrolidone, or a mixed solvent thereof is preferable.
- the solid content concentration of the slurry for the porous membrane is not particularly limited as long as it can be applied and immersed and has a fluid viscosity, but is generally about 10 to 50% by weight.
- the slurry for the porous film may contain optional components such as a dispersant and an electrolyte additive having a function of inhibiting the decomposition of the electrolyte, in addition to the nonconductive particles, the block polymer, and the solvent. Good. These are not particularly limited as long as they do not affect the battery reaction.
- the manufacturing method of the slurry for porous membranes is not particularly limited, and can be obtained by mixing the non-conductive particles, the block polymer, and the solvent and optional components added as necessary.
- a porous film slurry in which non-conductive particles are highly dispersed can be obtained by using the above components, regardless of the mixing method and mixing order.
- the mixing device is not particularly limited as long as it can uniformly mix the above components, and a ball mill, a sand mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, a planetary mixer, and the like can be used.
- the viscosity of the slurry for the porous membrane is preferably 10 mPa ⁇ S to 10,000 mPa ⁇ S, more preferably 50 to 500 mPa ⁇ s, from the viewpoints of uniform coatability and slurry aging stability.
- the viscosity is a value measured using a B-type viscometer at 25 ° C. and a rotation speed of 60 rpm.
- the substrate is not particularly limited, but the porous membrane for a secondary battery of the present invention is formed on an electrode for a secondary battery or an organic separator. It is preferable. Among these, it is more preferable to form on the electrode surface for secondary batteries.
- the porous membrane for a secondary battery of the present invention on the electrode surface, high safety is maintained without causing a short circuit between the positive electrode and the negative electrode even when the organic separator shrinks due to heat.
- the porous membrane for a secondary battery of the present invention on the electrode surface, the porous membrane can function as a separator even without an organic separator, and a battery can be produced at low cost. become.
- porous film for secondary batteries of this invention you may form on base materials other than an electrode and an organic separator.
- the porous membrane for a secondary battery of the present invention is formed on a substrate other than an electrode or an organic separator, the porous membrane is peeled off from the substrate and directly laminated on the electrode or the organic separator when assembling the battery. Can be used.
- the method for applying the slurry for the porous film onto the substrate is not particularly limited. Examples thereof include a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, and a brush coating method. Among them, the dip method and the gravure method are preferable in that a uniform porous film can be obtained.
- the drying method include drying by warm air, hot air, low-humidity air, vacuum drying, and drying by irradiation with (far) infrared rays or electron beams. The drying temperature can be changed depending on the type of solvent used.
- a low-volatility solvent such as N-methylpyrrolidone
- it is preferably dried at a high temperature of 120 ° C. or higher with a blower-type dryer.
- a highly volatile solvent when used, it can be dried at a low temperature of 100 ° C. or lower.
- drying at a low temperature of 100 ° C. or lower is preferable.
- the adhesion between the electrode mixture layer and the porous film can be improved by a press treatment using a mold press or a roll press.
- the pressure treatment is excessively performed, the porosity of the porous film may be impaired, so the pressure and the pressure time are controlled appropriately.
- the film thickness of the porous film is not particularly limited and is appropriately set according to the use or application field of the porous film. However, if the film is too thin, a uniform film cannot be formed. Since the capacity per volume (weight) decreases, 0.5 to 50 ⁇ m is preferable, and 0.5 to 10 ⁇ m is more preferable.
- the porous membrane for a secondary battery of the present invention is formed on the surface of the electrode mixture layer of the secondary battery electrode or the organic separator, and is particularly preferably used as a protective film or separator for the electrode mixture layer.
- the secondary battery electrode on which the porous film is formed is not particularly limited, and the porous film for a secondary battery of the present invention can be formed on electrodes having various configurations.
- the porous film may be formed on any surface of the positive electrode and the negative electrode of the secondary battery, or may be formed on both the positive electrode and the negative electrode.
- Electrode for secondary battery In the secondary battery electrode of the present invention, an electrode mixture layer containing a binder and an electrode active material is attached to a current collector, and the porous film is laminated on the surface of the electrode mixture layer. Being done. That is, the electrode for a secondary battery of the present invention is provided on a current collector, an electrode mixture layer including a binder and an electrode active material provided on the current collector, and the electrode mixture layer. In addition, the layer of the porous membrane for a secondary battery of the present invention is included.
- Electrode active material What is necessary is just to select the electrode active material used for the electrode for secondary batteries of this invention according to the secondary battery in which an electrode is utilized.
- the secondary battery include a lithium ion secondary battery and a nickel hydride secondary battery.
- the electrode active material (positive electrode active material) for the lithium ion secondary battery positive electrode is composed of an inorganic compound and an organic compound. It is roughly divided into Examples of the positive electrode active material made of an inorganic compound include transition metal oxides, composite oxides of lithium and transition metals, and transition metal sulfides. As the transition metal, Fe, Co, Ni, Mn and the like are used.
- the inorganic compound used for the positive electrode active material include LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , LiFePO 4 , LiFeVO 4 and other lithium-containing composite metal oxides; TiS 2 , TiS 3 , non- Transition metal sulfides such as crystalline MoS 2 ; transition metal oxides such as Cu 2 V 2 O 3 , amorphous V 2 O—P 2 O 5 , MoO 3 , V 2 O 5 , V 6 O 13 It is done. These compounds may be partially element-substituted.
- the positive electrode active material made of an organic compound for example, a conductive polymer compound such as polyacetylene or poly-p-phenylene can be used. Iron oxide having poor electrical conductivity may be used as an electrode active material covered with a carbon material by allowing a carbon source material to be present during reduction firing. These compounds may be partially element-substituted.
- the positive electrode active material for a lithium ion secondary battery may be a mixture of the above inorganic compound and organic compound.
- the particle diameter of the positive electrode active material is appropriately selected in consideration of other constituent elements of the battery. From the viewpoint of improving battery characteristics such as output characteristics and cycle characteristics, the 50% volume cumulative diameter is usually 0.1. It is ⁇ 50 ⁇ m, preferably 1 to 20 ⁇ m. When the 50% volume cumulative diameter is within this range, a secondary battery having a large charge / discharge capacity can be obtained, and handling of the slurry for electrodes and the electrodes is easy.
- the 50% volume cumulative diameter can be determined by measuring the particle size distribution by laser diffraction.
- examples of the electrode active material (negative electrode active material) for the lithium ion secondary battery negative electrode include amorphous carbon, graphite, natural graphite, Examples thereof include carbonaceous materials such as mesocarbon microbeads and pitch carbon fibers, and conductive polymer compounds such as polyacene.
- the negative electrode active material metals such as silicon, tin, zinc, manganese, iron, nickel, alloys thereof, oxides or sulfates of the metals or alloys are used.
- lithium alloys such as lithium metal, Li—Al, Li—Bi—Cd, and Li—Sn—Cd, lithium transition metal nitride, silicon, and the like can be used.
- the electrode active material a material obtained by attaching a conductivity imparting material to the surface by a mechanical modification method can also be used.
- the particle size of the negative electrode active material is appropriately selected in consideration of the other structural requirements of the battery. From the viewpoint of improving battery characteristics such as initial efficiency, output characteristics, and cycle characteristics, a 50% volume cumulative diameter is usually The thickness is 1 to 50 ⁇ m, preferably 15 to 30 ⁇ m.
- nickel hydroxide particles may be mentioned as an electrode active material (positive electrode active material) for a nickel metal hydride secondary battery positive electrode.
- the nickel hydroxide particles may be dissolved in cobalt, zinc, cadmium, or the like, or may be coated with a cobalt compound whose surface is subjected to an alkali heat treatment.
- nickel hydroxide particles include cobalt compounds such as cobalt oxide, metal cobalt and cobalt hydroxide, zinc compounds such as metal zinc, zinc oxide and zinc hydroxide, and rare earth compounds such as erbium oxide.
- the additive may be contained.
- the hydrogen storage alloy particles are used when charging the battery.
- an electrode active material negative electrode active material
- the hydrogen storage alloy particles are used when charging the battery.
- the hydrogen storage alloy particles are preferred. Specifically, for example, LaNi 5 , MmNi 5 (Mm is a misch metal), LmNi 5 (Lm is at least one selected from rare earth elements including La), and a part of Ni of these alloys is Al, Mn, Co.
- hydrogen storage alloy particles having a composition represented by the general formula: LmNiwCoxMnyAlz (the total value of atomic ratios w, x, y, z is 4.80 ⁇ w + x + y + z ⁇ 5.40) This is suitable because the pulverization associated with is suppressed and the charge / discharge cycle life is improved.
- the electrode mixture layer contains a binder in addition to the electrode active material.
- the binder By including the binder, the binding property of the electrode mixture layer in the electrode is improved, the strength against mechanical force applied during the process of winding the electrode is increased, and the electrode mixture layer in the electrode Since it becomes difficult to detach
- Various resin components can be used as the binder.
- polyethylene polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyacrylic acid derivatives, polyacrylonitrile derivatives, and the like can be used. These may be used alone or in combination of two or more.
- the soft polymer illustrated below can also be used as a binder.
- Acrylic acid such as polybutyl acrylate, polybutyl methacrylate, polyhydroxyethyl methacrylate, polyacrylamide, polyacrylonitrile, butyl acrylate / styrene copolymer, butyl acrylate / acrylonitrile copolymer, butyl acrylate / acrylonitrile / glycidyl methacrylate copolymer
- an acrylic soft polymer which is a homopolymer of a methacrylic acid derivative or a copolymer with a monomer copolymerizable therewith;
- Isobutylene soft polymers such as polyisobutylene, isobutylene-isoprene rubber, isobutylene-styrene copolymer; Polybutadiene, polyisoprene, butadiene / styrene random copolymer, isopre
- Olefin soft polymer of Vinyl soft polymers such as polyvinyl alcohol, polyvinyl acetate, polyvinyl stearate, vinyl acetate / styrene copolymer; Epoxy soft polymers such as polyethylene oxide, polypropylene oxide, epichlorohydrin rubber; Fluorine-containing soft polymers such as vinylidene fluoride rubber and tetrafluoroethylene-propylene rubber; Other soft polymers such as natural rubber, polypeptide, protein, polyester thermoplastic elastomer, vinyl chloride thermoplastic elastomer, polyamide thermoplastic elastomer and the like can be mentioned. These soft polymers may have a cross-linked structure or may have a functional group introduced by modification.
- the amount of the binder in the electrode mixture layer is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 4 parts by weight, particularly preferably 0.5 to 4 parts by weight with respect to 100 parts by weight of the electrode active material. 3 parts by weight.
- the amount of the binder is within the above range, it is possible to prevent the active material from dropping from the electrode without inhibiting the battery reaction.
- the binder is prepared as a solution or dispersion to produce an electrode.
- the viscosity at that time is usually in the range of 1 mPa ⁇ S to 300,000 mPa ⁇ S, preferably 50 mPa ⁇ S to 10,000 mPa ⁇ S.
- the viscosity is a value measured using a B-type viscometer at 25 ° C. and a rotation speed of 60 rpm.
- the electrode mixture layer may contain a conductivity imparting material or a reinforcing material.
- a conductivity imparting material conductive carbon such as acetylene black, ketjen black, carbon black, graphite, vapor-grown carbon fiber, and carbon nanotube can be used. Examples thereof include carbon powders such as graphite, and fibers and foils of various metals.
- the reinforcing material various inorganic and organic spherical, plate-like, rod-like or fibrous fillers can be used.
- the amount of the conductivity-imparting material and the reinforcing agent used is usually 0 to 20 parts by weight, preferably 1 to 10 parts by weight with respect to 100 parts by weight of the electrode active material.
- the electrode mixture layer can be formed by adhering a slurry containing a binder, an electrode active material, and a solvent (hereinafter sometimes referred to as “electrode mixture layer forming slurry”) to a current collector. .
- any solvent that dissolves or disperses the binder in the form of particles may be used, but a solvent that dissolves is preferable.
- the binder is adsorbed on the surface, thereby stabilizing the dispersion of the electrode active material and the like.
- organic solvents include cycloaliphatic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; ketones such as ethyl methyl ketone and cyclohexanone; ethyl acetate, butyl acetate, ⁇ -butyrolactone, ⁇ -Esters such as caprolactone; Acylonitriles such as acetonitrile and propionitrile; Ethers such as tetrahydrofuran and ethylene glycol diethyl ether: Alcohols such as methanol, ethanol, isopropanol, ethylene glycol and ethylene glycol monomethyl ether; N-methyl Amides such as pyrrolidone and N, N-dimethylformamide are exemplified. These solvents may be used alone or in admixture of
- the electrode mixture layer forming slurry may contain a thickener.
- a polymer soluble in the solvent used for the slurry for forming the electrode mixture layer is used.
- the thickener illustrated with the porous film for secondary batteries of this invention can be used.
- the amount of the thickener used is preferably 0.5 to 1.5 parts by weight with respect to 100 parts by weight of the electrode active material. When the use amount of the thickener is within this range, the coating property and the adhesion with the current collector are good.
- the electrode mixture layer forming slurry contains trifluoropropylene carbonate, vinylene carbonate, catechol carbonate, 1,6-dioxaspiro [4,4] nonane in order to increase the stability and life of the battery.
- -2,7-dione, 12-crown-4-ether and the like can be used. These may be used by being contained in an electrolyte solution described later.
- the amount of the solvent in the electrode mixture layer forming slurry is adjusted so as to have a viscosity suitable for coating according to the type of the electrode active material and the binder.
- the solid content concentration of other additives such as the electrode active material, the binder and the conductivity imparting agent is preferably 30 to 90% by weight, More preferably, the amount is adjusted to 40 to 80% by weight.
- the electrode mixture layer forming slurry is obtained by mixing an electrode active material, a binder, other additives such as a conductivity imparting agent added as necessary, and a solvent using a mixer. Mixing may be performed by supplying the above components all at once to a mixer.
- an electrode active material, a binder, a conductivity-imparting material, and a thickener are used as constituents of the electrode mixture layer forming slurry, the conductivity-imparting material and the thickener are mixed in a solvent to conduct electricity. It is preferable to disperse the imparting material in the form of fine particles, and then add a binder and an electrode active material and further mix, since the dispersibility of the resulting slurry can be improved.
- a ball mill, sand mill, pigment disperser, crusher, ultrasonic disperser, homogenizer, planetary mixer, Hobart mixer, etc. can be used. It is preferable because aggregation of the resin can be suppressed.
- the particle size of the electrode mixture layer forming slurry is preferably 35 ⁇ m or less, and more preferably 25 ⁇ m or less.
- the conductive material is highly dispersible and a homogeneous electrode can be obtained.
- the current collector is not particularly limited as long as it is an electrically conductive and electrochemically durable material. From the viewpoint of having heat resistance, for example, iron, copper, aluminum, nickel, stainless steel, etc. Metal materials such as titanium, tantalum, gold, and platinum are preferable. Among these, aluminum is particularly preferable for the positive electrode of the lithium ion secondary battery, and copper is particularly preferable for the negative electrode of the lithium ion secondary battery.
- the shape of the current collector is not particularly limited, but a sheet shape having a thickness of about 0.001 to 0.5 mm is preferable. In order to increase the adhesive strength of the electrode mixture layer, the current collector is preferably used after being roughened.
- Examples of the roughening method include a mechanical polishing method, an electrolytic polishing method, and a chemical polishing method.
- a mechanical polishing method an abrasive cloth paper with a fixed abrasive particle, a grindstone, an emery buff, a wire brush provided with a steel wire or the like is used.
- an intermediate layer may be formed on the current collector surface in order to increase the adhesive strength and conductivity of the electrode mixture layer.
- the method for producing the electrode mixture layer may be any method in which the electrode mixture layer is bound in layers on at least one side, preferably both sides of the current collector.
- the electrode mixture layer forming slurry is applied to a current collector, dried, and then heated at 120 ° C. or higher for 1 hour or longer to form an electrode mixture layer.
- the method for applying the electrode mixture layer forming slurry to the current collector is not particularly limited. Examples thereof include a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, and a brush coating method.
- the drying method include drying by warm air, hot air, low-humidity air, vacuum drying, and drying by irradiation with (far) infrared rays or electron beams.
- the porosity of the electrode mixture layer of the electrode is preferably cured.
- the thickness of the electrode mixture layer is usually 5 to 300 ⁇ m, preferably 10 to 250 ⁇ m, for both the positive electrode and the negative electrode.
- the separator for a secondary battery of the present invention is formed by laminating the porous membrane for a secondary battery on an organic separator layer. That is, the separator for a secondary battery of the present invention includes an organic separator layer and the porous film for a secondary battery of the present invention provided on the organic separator layer.
- organic separator layer known ones such as a separator containing a polyolefin resin such as polyethylene or polypropylene or an aromatic polyamide resin are used.
- a porous film having a fine pore size and having no electron conductivity and ionic conductivity and high resistance to organic solvents is used.
- polyolefin polyethylene, polypropylene, polybutene, polychlorinated.
- a microporous film made of a resin such as a mixture or a copolymer thereof, polyethylene terephthalate, polycycloolefin, polyether sulfone, polyamide, polyimide, polyimide amide, polyaramid, polycycloolefin, nylon, polytetrafluoroethylene
- a microporous membrane made of a resin such as those woven with polyolefin fibers, a nonwoven fabric thereof, and an aggregate of insulating substance particles.
- the coating property of the above-mentioned slurry for porous membranes is excellent, and since the thickness of the whole separator can be reduced and the active material ratio in the battery can be increased to increase the capacity per volume, it is made of polyolefin resin.
- a microporous membrane is preferred.
- the thickness of the organic separator layer is usually 0.5 to 40 ⁇ m, preferably 1 to 30 ⁇ m, more preferably 1 to 10 ⁇ m. Within this range, the resistance due to the separator in the battery is reduced, and the workability at the time of coating on the organic separator layer is good.
- examples of the polyolefin resin used as the material for the organic separator layer include homopolymers such as polyethylene and polypropylene, copolymers, and mixtures thereof.
- examples of the polyethylene include low density, medium density, and high density polyethylene, and high density polyethylene is preferable from the viewpoint of piercing strength and mechanical strength. These polyethylenes may be mixed in two or more types for the purpose of imparting flexibility.
- the polymerization catalyst used for these polyethylenes is not particularly limited, and examples thereof include a Ziegler-Natta catalyst, a Phillips catalyst, and a metallocene catalyst.
- the viscosity average molecular weight of polyethylene is preferably 100,000 or more and 12 million or less, more preferably 200,000 or more and 3 million or less.
- polypropylene include homopolymers, random copolymers, and block copolymers, and one kind or a mixture of two or more kinds can be used.
- the polymerization catalyst is not particularly limited, and examples thereof include a Ziegler-Natta catalyst and a metallocene catalyst.
- the stereoregularity is not particularly limited, and isotactic, syndiotactic or atactic can be used. However, it is desirable to use isotactic polypropylene because it is inexpensive.
- an appropriate amount of a polyolefin other than polyethylene or polypropylene, and an additive such as an antioxidant or a nucleating agent may be added to the polyolefin as long as the effects of the present invention are not impaired.
- an organic separator layer of polyolefin As a method for producing an organic separator layer of polyolefin, a publicly known one is used.For example, after forming a film of polypropylene and polyethylene by extrusion, a crystal domain is grown at a low temperature and stretched in this state.
- a wet method in which a microporous film is formed by removing a film that has started to form a gathered island phase by using this solvent or other low-molecular solvent with another volatile solvent is selected.
- a dry method is preferable in that a large void can be easily obtained for the purpose of reducing the resistance.
- the organic separator layer used in the present invention may contain other fillers and fiber compounds for the purpose of controlling strength, hardness, and heat shrinkage rate.
- it when laminating the porous film, it may be coated with a low molecular weight compound or a high molecular compound in advance for the purpose of improving the adhesion or improving the liquid impregnation property by lowering the surface tension with the electrolytic solution.
- electromagnetic radiation treatment such as ultraviolet rays, plasma treatment such as corona discharge and plasma gas may be performed.
- the coating treatment is preferably performed with a polymer compound containing a polar group such as a carboxylic acid group, a hydroxyl group, and a sulfonic acid group from the viewpoint that the impregnation property of the electrolytic solution is high and the adhesion with the porous film is easily obtained.
- a polar group such as a carboxylic acid group, a hydroxyl group, and a sulfonic acid group
- the secondary battery of the present invention includes a positive electrode, a negative electrode, a separator, and an electrolyte solution, and the porous film is laminated on at least one of the positive electrode, the negative electrode, and the separator. That is, the secondary battery of the present invention is a secondary battery including a positive electrode, a negative electrode, a separator, and an electrolyte solution, and at least one of the positive electrode, the negative electrode, and the separator includes the porous film for a secondary battery of the present invention. Including.
- Examples of the secondary battery include a lithium ion secondary battery and a nickel hydride secondary battery.
- improvement of safety is most demanded and the effect of introducing a porous film is the highest, and in addition, improvement of output characteristics is cited as an issue. Therefore, a lithium ion secondary battery is preferable.
- the case where it uses for a lithium ion secondary battery is demonstrated.
- Electrode As the electrolytic solution for the lithium ion secondary battery, an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is used. A lithium salt is used as the supporting electrolyte.
- the lithium salt is not particularly limited, LiPF 6, LiAsF 6, LiBF 4, LiSbF 6, LiAlCl 4, LiClO 4, CF 3 SO 3 Li, C 4 F 9 SO 3 Li, CF 3 COOLi, (CF 3 CO) 2 NLi, (CF 3 SO 2 ) 2 NLi, (C 2 F 5 SO 2 ) NLi, and the like.
- LiPF 6 , LiClO 4 , and CF 3 SO 3 Li that are easily soluble in a solvent and exhibit a high degree of dissociation are preferable. Two or more of these may be used in combination. Since the lithium ion conductivity increases as the supporting electrolyte having a higher degree of dissociation is used, the lithium ion conductivity can be adjusted depending on the type of the supporting electrolyte.
- the organic solvent used in the electrolyte for the lithium ion secondary battery is not particularly limited as long as it can dissolve the supporting electrolyte, but dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene Carbonates such as carbonate (PC), butylene carbonate (BC) and methyl ethyl carbonate (MEC); esters such as ⁇ -butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfolane and dimethyl sulfoxide Sulfur-containing compounds such as are preferably used. Moreover, you may use the liquid mixture of these solvents.
- DMC dimethyl carbonate
- EC ethylene carbonate
- DEC diethyl carbonate
- PC butylene carbonate
- MEC methyl ethyl carbonate
- esters such as ⁇ -butyrolactone and methyl formate
- ethers such as 1,2-d
- carbonates are preferable because they have a high dielectric constant and a wide stable potential region. Since the lithium ion conductivity increases as the viscosity of the solvent used decreases, the lithium ion conductivity can be adjusted depending on the type of the solvent. Moreover, it is also possible to use the electrolyte solution by containing an additive. Examples of the additive include carbonate compounds such as vinylene carbonate (VC) used in the electrode mixture layer slurry.
- VC vinylene carbonate
- the concentration of the supporting electrolyte in the electrolytic solution for a lithium ion secondary battery is usually 1 to 30% by weight, preferably 5% to 20% by weight.
- the concentration is usually 0.5 to 2.5 mol / L depending on the type of the supporting electrolyte. If the concentration of the supporting electrolyte is too low or too high, the ionic conductivity tends to decrease. Since the degree of swelling of the polymer particles increases as the concentration of the electrolytic solution used decreases, the lithium ion conductivity can be adjusted by the concentration of the electrolytic solution.
- electrolytic solution other than the above examples include polymer electrolytes such as polyethylene oxide and polyacrylonitrile, gelled polymer electrolytes in which the polymer electrolyte is impregnated with an electrolytic solution, and inorganic solid electrolytes such as LiI and Li 3 N.
- the organic separator illustrated by the above-mentioned separator for secondary batteries is mentioned.
- the positive electrode and the negative electrode include those in which an electrode mixture layer containing a binder and an electrode active material exemplified in the secondary battery electrode is attached to a current collector.
- the positive electrode or the negative electrode in which the porous film is laminated may be used as the positive electrode or the negative electrode, and the separator in which the porous film is laminated may be the secondary battery.
- a battery separator may be used as the separator.
- a positive electrode and a negative electrode are overlapped via a separator, and this is wound into a battery container according to the shape of the battery.
- the method of injecting and sealing is mentioned.
- the porous membrane for a secondary battery of the present invention is formed on any one of a positive electrode, a negative electrode, and a separator. In addition, lamination with only a porous film is possible. If necessary, an expanded metal, an overcurrent prevention element such as a fuse or a PTC element, a lead plate, or the like can be inserted to prevent an increase in pressure inside the battery and overcharge / discharge.
- the shape of the battery may be any of a coin shape, a button shape, a sheet shape, a cylindrical shape, a square shape, a flat shape, and the like.
- B Settling is observed after 6 to 10 days.
- C Sedimentation is observed within 24 hours to 5 days.
- D Sedimentation is observed for 10 hours or more and less than 24 hours.
- E Sedimentation is observed for 3 hours or more and less than 10 hours.
- F Settling is observed in less than 3 hours.
- cycle characteristics The obtained full-cell coin-type battery was charged at 3 ° C to 4.3V at 0.1C at 25 ° C, and then charged / discharged from 4.3V to 3V at 0.1C for 100 cycles.
- ⁇ Battery characteristics low temperature characteristics>
- the obtained laminated cell type batteries were charged at a constant current until the voltage became 4.2 V by a constant current constant voltage charging method at a charge / discharge rate of 0.1 C at 25 ° C., respectively, and charged at a constant voltage. Thereafter, the battery is discharged to 0.1 V at 0.1 C, and the discharge capacity at 25 ° C. is obtained. Thereafter, constant current and constant voltage charging was performed at 0.1 C in a thermostat set to ⁇ 20 ° C.
- the battery capacity at 25 ° C. is a
- the battery capacity at ⁇ 20 ° C. is b.
- the low-temperature capacity retention represented by the ratio (b / a (%)) of the battery capacity b at ⁇ 20 ° C. and the battery capacity a at 25 ° C. was determined and used as an index of low-temperature characteristics. It shows that it is a battery with a favorable lithium acceptability in low temperature, so that this value is large.
- Example 1 ⁇ Synthesis of block polymer> After adding 40 parts of styrene to a four-necked flask equipped with a mechanical stirrer, nitrogen inlet, cooling tube and rubber septum, 1.3 parts of 2,2′-bipyridine was added thereto, Was replaced with nitrogen. To this was added 0.41 part of copper bromide under a nitrogen stream, the reaction system was heated to 90 ° C., and 0.6 part of 2-hydroxyethyl 2-bromo-2-methylpropionate was added as an initiator. Then, polymerization was started, and polymerization was performed at 90 ° C. for 9 hours under a nitrogen stream without adding a solvent.
- the polymerization rate (a ratio defined by dividing the weight of the polymer after heating and removing the volatile component by the weight of the polymer as it was before removing the volatile component) is 80% or more.
- n-butyl acrylate was added to this.
- the resulting mixture containing the block polymer was heated to 120 ° C. and centrifuged at 20000 G for 1 hour to obtain a crude purified block polymer (green) as a supernatant.
- the weight average molecular weight was determined by dissolving polymer-1 in tetrahydrofuran to give a 0.2 wt% solution, followed by filtration with a 0.45 ⁇ m membrane filter, and using gel permeation chromatography (GPC) as a measurement sample. The measurement was performed under conditions, and the weight average molecular weight in terms of standard polystyrene was determined.
- Measuring device HLC-8220GPC (manufactured by Tosoh Corporation) Column: TSKgel Multipore HXL-M (manufactured by Tosoh Corporation) Eluent: Tetrahydrofuran (THF) Elution rate: 0.3 ml / min Detector: RI (polarity (+)) Column temperature: 40 ° C
- NMP N-methyl-2-pyrrolidone
- ⁇ Creation of slurry for porous membrane The non-conductive particles (aluminum oxide, average particle size 0.3 ⁇ m, iron content ⁇ 20 ppm) and the polymer-1 solution so as to have a content ratio of 100: 2.5 (solid content equivalent ratio). Further, NMP was mixed so that the solid content concentration was 30% and dispersed using a bead mill to prepare a slurry 1 for porous membrane. The dispersibility of the obtained slurry for porous membrane was measured. The results are shown in Table 2.
- the mixture was mixed with a planetary mixer to prepare a slurry-like electrode composition for negative electrode (slurry for forming a negative electrode mixture layer).
- This negative electrode composition was applied to one side of a 10 ⁇ m thick copper foil, dried at 110 ° C. for 3 hours, and then roll pressed to obtain a negative electrode having a negative electrode mixture layer having a thickness of 60 ⁇ m.
- Electrode composition for positive electrode and positive electrode 92 parts of lithium manganate having a spinel structure as a positive electrode active material, 5 parts of acetylene black, and 3 parts of PVDF (polyvinylidene fluoride) as a binder are added to a solid content, and the solid content concentration is increased to 87% with NMP. After adjustment, the mixture was mixed for 60 minutes with a planetary mixer. Further, the solid content concentration was adjusted to 84% with NMP, and then mixed for 10 minutes to prepare a slurry-like electrode composition for positive electrode (slurry for forming a positive electrode mixture layer). This positive electrode composition was applied to an aluminum foil having a thickness of 18 ⁇ m, dried at 120 ° C. for 3 hours, and then roll-pressed to obtain a positive electrode having a positive electrode mixture layer having a thickness of 50 ⁇ m.
- PVDF polyvinylidene fluoride
- the porous film slurry 1 was applied using a wire bar so that the thickness of the porous film layer after drying was 5 ⁇ m, and then 90 ° C. was dried for 10 minutes to form a porous film, and a negative electrode 1 with a porous film having a layer structure of (copper foil) / (negative electrode mixture layer) / (porous film) was obtained.
- the obtained positive electrode was cut out into a circle having a diameter of 13 mm.
- the obtained negative electrode 1 with a porous film was cut out into a circle having a diameter of 14 mm.
- a single-layer polypropylene separator (porosity 55%) manufactured by a dry method having a thickness of 25 ⁇ m was cut into a circle having a diameter of 18 mm. These were housed in a stainless steel coin-type outer container (diameter 20 mm, height 1.8 mm, stainless steel thickness 0.25 mm) provided with polypropylene packing. The arrangement of these circular electrodes and separators was as follows. The circular positive electrode was disposed so that the aluminum foil was in contact with the bottom surface of the outer container.
- the circular separator was disposed so as to be interposed between the circular positive electrode and the circular negative electrode 1 with a porous film.
- a battery container was prepared using a laminate film made of an aluminum sheet and a resin made of polypropylene covering both surfaces thereof. Subsequently, the mixture layer and the porous film were removed from the end portions of the positive electrode and the negative electrode with the porous film obtained above to form a portion where the copper foil or the aluminum foil was exposed. A Ni tab was welded to the location where the aluminum foil of the positive electrode was exposed, and a Cu tab was welded to the location where the copper foil of the negative electrode was exposed. The obtained positive electrode with a tab and negative electrode with a porous film with a tab were stacked with a separator made of a polyethylene microporous film interposed therebetween.
- the surface of the electrode was disposed in a direction in which the surface on the mixture layer side of the positive electrode and the surface on the porous film side of the negative electrode with the porous film faced each other.
- the stacked electrodes and separator were wound and stored in the battery container.
- an electrolytic solution in which LiPF 6 was dissolved to a concentration of 1 mol / liter was injected into a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 2 at 25 ° C.
- the laminate film was sealed, and the laminate cell which is the lithium ion secondary battery of this invention was produced.
- the obtained battery was measured for low temperature characteristics. The evaluation results are shown in Table 3.
- Example 2 Polymers 2 to 4 having the compositions shown in Table 1 were used in place of polymer-1 as the binder constituting the porous membrane (that is, the monomer constituting segment A and the unit constituting segment B). ⁇ Synthesis of block polymer> in Example 1 except that monomers of the type shown as structures “A” and “B” in Table 1 were used in place of n-butyl acrylate and styrene, respectively. Polymers 2 to 4 were obtained in the same manner as in Example 1 except that this was used, and a slurry for porous membrane, an electrode with a porous membrane, and a battery were produced in the same manner as in Example 1. And the dispersibility of the obtained slurry for porous films, the output characteristics of the obtained battery, and the cycle characteristics were evaluated. The results are shown in Table 2.
- Example 5 ⁇ Synthesis of block polymer> The block polymer was the same as in Example 1 except that the polymerization time when styrene was added was changed from 9 hours to 36 hours and the polymerization time when n-butyl acrylate was added was changed from 12 hours to 48 hours.
- the block polymer was the same as in Example 1 except that the polymerization time when styrene was added was changed from 9 hours to 36 hours and the polymerization time when n-butyl acrylate was added was changed from 12 hours to 48 hours.
- the polymerization reaction time at 90 ° C. after adding styrene and other substances (initiator, etc.) to the flask was changed from 9 hours to 36 hours.
- the time for heating to 110 ° C. after adding 60 parts of n-butyl acrylate to the reaction mixture was changed from 12 hours to 48 hours.
- Table 1 shows the composition, ratio, weight average molecular weight, and glass transition temperature of the polymer-5 obtained.
- Example 1 a slurry for porous film, an electrode with a porous film, and a battery were prepared in the same manner as in Example 1 except that Polymer-5 was used instead of Polymer-1 as a binder constituting the porous film. Produced. And the dispersibility of the obtained slurry for porous films, the output characteristics of the obtained battery, and the cycle characteristics were evaluated. The results are shown in Table 2.
- Example 6 ⁇ Synthesis of block polymer> The block polymer was the same as in Example 1 except that the polymerization time when styrene was added was changed from 9 hours to 1 hour and the polymerization time when n-butyl acrylate was added was changed from 12 hours to 2 hours.
- Example 6 The block polymer was the same as in Example 1 except that the polymerization time when styrene was added was changed from 9 hours to 1 hour and the polymerization time when n-butyl acrylate was added was changed from 12 hours to 2 hours.
- the polymerization reaction time at 90 ° C. after adding styrene and other substances (initiator, etc.) to the flask was changed from 9 hours to 1 hour.
- the time for heating to 110 ° C. after adding 60 parts of n-butyl acrylate to the reaction mixture was changed from 12 hours to 2 hours.
- Example 1 The composition, ratio, weight average molecular weight, and glass transition temperature of the obtained polymer-6 are shown in Table 1.
- Example 1 a slurry for porous film, an electrode with a porous film, and a battery were prepared in the same manner as in Example 1 except that Polymer-6 was used instead of Polymer-1 as a binder constituting the porous film. Produced. And the dispersibility of the obtained slurry for porous films, the output characteristics of the obtained battery, and the cycle characteristics were evaluated. The results are shown in Table 2.
- Example 7 ⁇ Synthesis of block polymer> The amount of styrene added was changed from 40 parts to 20 parts, the amount of n-butyl acrylate added was changed from 60 parts to 80 parts, and the polymerization time when styrene was added was changed from 9 hours to 6 hours ( That is, the polymerization reaction time at 90 ° C. after adding styrene and other substances (initiator, etc.) to the flask was changed from 9 hours to 6 hours), and the polymerization time when n-butyl acrylate was added was Same as Example 1 except that the time was changed from 12 hours to 20 hours (ie, the time for heating to 110 ° C.
- Example 1 the slurry for porous film, the electrode with porous film, and the battery were prepared in the same manner as in Example 1 except that Polymer-7 was used instead of Polymer-1 as the binder constituting the porous film. Produced. And the dispersibility of the obtained slurry for porous films, the output characteristics of the obtained battery, and the cycle characteristics were evaluated. The results are shown in Table 2.
- Example 8 ⁇ Synthesis of block polymer> The amount of styrene added was changed from 40 parts to 80 parts, the amount of n-butyl acrylate added was changed from 20 parts to 80 parts, and the polymerization time when styrene was added was changed from 9 hours to 14 hours ( That is, the polymerization reaction time at 90 ° C. after adding styrene and other substances (initiator etc.) into the flask was changed from 9 hours to 14 hours), and the polymerization time when adding n-butyl acrylate was Same as Example 1 except that the time was changed from 12 hours to 8 hours (ie, the time for heating to 110 ° C.
- Example 1 a slurry for porous film, an electrode with a porous film, and a battery were prepared in the same manner as in Example 1 except that Polymer-8 was used instead of Polymer-1 as a binder constituting the porous film. Produced. And the dispersibility of the obtained slurry for porous films, the output characteristics of the obtained battery, and the cycle characteristics were evaluated. The results are shown in Table 2.
- Example 9 instead of polymer-1, polymers-9 to 10 having the composition shown in Table 1 were used as the binder constituting the porous membrane (that is, the monomer constituting segment A and the unit constituting segment B).
- Polymers 9 to 10 were obtained in the same manner as in Example 1 except that this was used, and a slurry for porous membrane, an electrode with a porous membrane, and a battery were produced in the same manner as in Example 1. And the dispersibility of the obtained slurry for porous films, the output characteristic of the obtained battery, cycle characteristics, and low temperature characteristics were evaluated. The results are shown in Tables 2 and 3.
- Example 11 ⁇ Creation of slurry for porous membrane>
- Non-conductive particles aluminum oxide, average particle size 0.3 ⁇ m, iron content ⁇ 20 ppm
- polymer-3 solution so as to have a content ratio of 100: 2.5 (solid content equivalent ratio).
- NMP was mixed so that the solid content concentration was 30% and dispersed using a bead mill to prepare a porous membrane slurry 11. The dispersibility of the obtained slurry for porous membrane was measured. The results are shown in Table 2.
- ⁇ Production of negative electrode composition and negative electrode> 98 parts of graphite having a particle diameter of 20 ⁇ m and a specific surface area of 4.2 m 2 / g as a negative electrode active material, and 5 parts of PVDF (polyvinylidene fluoride) as a binder are mixed, and N-methylpyrrolidone is further mixed.
- the mixture was mixed with a planetary mixer to prepare a slurry-like electrode composition for negative electrode (slurry for forming a negative electrode mixture layer).
- This negative electrode composition was applied to one side of a 10 ⁇ m thick copper foil, dried at 110 ° C. for 3 hours, and then roll pressed to obtain a negative electrode 11 having a negative electrode mixture layer having a thickness of 60 ⁇ m.
- Electrode composition for positive electrode and positive electrode 92 parts of lithium manganate having a spinel structure as a positive electrode active material, 5 parts of acetylene black, and 3 parts of PVDF (polyvinylidene fluoride) as a binder are added to a solid content, and the solid content concentration is increased to 87% with NMP. After adjustment, the mixture was mixed for 60 minutes with a planetary mixer. Further, the solid content concentration was adjusted to 84% with NMP, and then mixed for 10 minutes to prepare a slurry-like electrode composition for positive electrode (slurry for forming a positive electrode mixture layer). This positive electrode composition was applied to an aluminum foil having a thickness of 18 ⁇ m, dried at 120 ° C. for 3 hours, and then roll-pressed to obtain a positive electrode 11 having a positive electrode mixture layer having a thickness of 50 ⁇ m.
- PVDF polyvinylidene fluoride
- ⁇ Preparation of separator with porous membrane> On one surface of a single-layer polypropylene separator (porosity 55%) produced by a dry method having a thickness of 25 ⁇ m, the porous membrane layer after drying the porous membrane slurry 11 has a thickness of 5 ⁇ m.
- the film was coated using a wire bar, and then dried at 90 ° C. for 10 minutes to form a porous film on one side.
- the other side of the separator was similarly coated using a wire bar so that the thickness of the porous membrane layer after drying was 5 ⁇ m, and then dried at 90 ° C. for 10 minutes, A porous film was formed on the substrate to obtain a separator with a porous film.
- the positive electrode 11 was cut into a circle having a diameter of 13 mm.
- the negative electrode 11 was cut into a circle having a diameter of 14 mm.
- the separator with a porous membrane was cut into a circle having a diameter of 18 mm.
- These were housed in a stainless steel coin-type outer container (diameter 20 mm, height 1.8 mm, stainless steel thickness 0.25 mm) provided with polypropylene packing.
- the arrangement of these circular electrodes and separators was as follows.
- the circular positive electrode was disposed so that the aluminum foil was in contact with the bottom surface of the outer container.
- the circular separator was disposed so as to be interposed between the circular positive electrode and the circular negative electrode.
- Example 12 ⁇ Creation of slurry for porous membrane> Polymer-3 was dissolved in acetone to obtain an acetone solution of polymer-3 having a solid concentration of 20%. Non-conductive particles (cross-linked MMA (Sekisui Chemical Co., Ltd. SSX-101, average particle size: 1.0 ⁇ m)) and acetone solution of polymer-3 in a 100: 2.5 content ratio (solid content equivalent ratio) Then, acetone was further mixed so that the solid concentration was 30%, and dispersed using a bead mill to prepare a porous membrane slurry 12. The dispersibility of the obtained slurry for porous membrane was measured. The results are shown in Table 2.
- a slurry for a porous membrane, an electrode with a porous membrane, and a battery were prepared in the same manner as in Example 1 except that the porous membrane slurry 12 was used instead of the porous membrane slurry 1 as the porous membrane slurry. And the dispersibility of the obtained slurry for porous films, the output characteristic of the obtained battery, cycle characteristics, and low temperature characteristics were evaluated. The results are shown in Tables 2 and 3.
- Non-conductive particles (aluminum oxide, average particle size 0.3 ⁇ m, iron content ⁇ 20 ppm), a solution of polymer-3 (an NMP solution having a solid content of 20%), a 10% NMP solution of polyvinylidene fluoride, Are mixed so that the content ratio is 100: 1.25: 1.25 (solid content equivalent ratio), and NMP is further mixed to a solid content concentration of 30%, and dispersed using a bead mill.
- a membrane slurry 13 was prepared. The dispersibility of the obtained slurry for porous membrane was measured. The results are shown in Table 2.
- a slurry for a porous membrane, an electrode with a porous membrane, and a battery were prepared in the same manner as in Example 1 except that the porous membrane slurry 13 was used instead of the porous membrane slurry 1 as the porous membrane slurry. And the dispersibility of the obtained slurry for porous films, the output characteristic of the obtained battery, cycle characteristics, and low temperature characteristics were evaluated. The results are shown in Tables 2 and 3.
- Example 1 A slurry for a porous film and an electrode with a porous film were the same as in Example 1 except that polyvinylidene fluoride (glass transition temperature: ⁇ 40 ° C.) was used instead of polymer-1 as a binder constituting the porous film. And a battery were prepared. And the dispersibility of the obtained slurry for porous films, the output characteristics of the obtained battery, and the cycle characteristics were evaluated. The results are shown in Table 2.
- Example 2 A slurry for porous membrane, porous material as in Example 1, except that styrene-butadiene copolymer (glass transition temperature: ⁇ 15 ° C.) was used in place of polymer-1 as the binder constituting the porous membrane. A film-coated electrode and a battery were produced. And the dispersibility of the obtained slurry for porous films, the output characteristics of the obtained battery, and the cycle characteristics were evaluated. The results are shown in Table 2.
- Example 2 As in Example 1, except that n-butyl acrylate-styrene copolymer (glass transition temperature: 5 ° C.) was used in place of polymer-1 as a binder constituting the porous film. A slurry, an electrode with a porous film, and a battery were produced. And the dispersibility of the obtained slurry for porous films, the output characteristics of the obtained battery, and the cycle characteristics were evaluated. The results are shown in Table 2.
- BA is n-butyl acrylate
- ST is styrene
- AN is acrylonitrile
- 2EHA is 2-ethylhexyl acrylate
- MA is methyl acrylate
- EA represents ethyl acrylate
- PVDF polyvinylidene fluoride
- BD represents butadiene.
- the slurry for porous film having excellent dispersibility, lithium ion having excellent output characteristics and cycle characteristics can be obtained.
- a secondary battery can be obtained.
- Examples 1, 3, and 2 having segments having high compatibility with the electrolyte and segments having low compatibility, and having a weight average molecular weight in the range of 5,000 to 100,000.
- Examples Nos. 7 to 10 have excellent dispersibility and cycle characteristics of the slurry for the porous membrane, and in particular, have a segment having a glass transition temperature of ⁇ 40 ° C. or lower, and have styrene as a segment having high compatibility with the electrolytic solution. No.
- Comparative Examples 1 to 3 using a polymer having no block structure as the binder are inferior in all of the dispersibility of the slurry for the porous membrane, the output characteristics of the battery, and the cycle characteristics. Remarkably inferior.
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Cell Separators (AREA)
Abstract
Description
例えば、特許文献1には、電極上にアルミナ、シリカ、ポリエチレン樹脂などの微粒子と、ポリフッ化ビニリデン等の耐電解液性の高い結着剤とを含むスラリーを用いて形成されてなる多孔性保護膜が開示されている。これらの多孔膜保護膜の場合は、例えば150℃以上で有機セパレーターの熱収縮が起こっても、電極上に微粒子があることにより内部短絡率が低下し安全性が向上する。
さらに、特許文献2には、アルミナや有機化合物等の微粒子と、スチレンーブタジエン共重合体等の結着剤とが、離型性を有するライナー上に形成されてなる多孔質膜が開示されている。これらの多孔質膜の場合は、熱収縮が起こらないことによる内部短絡率の低下に加え、多孔質膜が熱膨潤することによりシャットダウンが起こり、信頼性や安全性が更に向上している。
また、長期サイクル特性も向上させるためには、多孔膜の電解液保持性や電解液含浸性を更に向上させる必要であることがわかった。
従って、本発明の目的は、出力特性及び長期サイクル特性が更に向上した、リチウムイオン二次電池などに使用される多孔膜、かかる多孔膜を得るためのスラリー及び製造方法、並びに、出力特性及び長期サイクル特性が更に向上した、リチウムイオン二次電池及びその構成要素を提供することにある。
(1)非導電性粒子及びブロックポリマーを含む二次電池用多孔膜。
(2)前記ブロックポリマーが、エチレンカーボネートとジエチルカーボネートを含有する二次電池用電解液に対する相溶性を示すセグメントと前記二次電池用電解液に対する相溶性を示さないセグメントである2つのセグメントを有する(1)に記載の二次電池用多孔膜。
(3)前記ブロックポリマーの重量平均分子量が、1,000~500,000の範囲にある(1)~(2)のいずれかに記載の二次電池用多孔膜。
(4)前記ブロックポリマーが、ガラス転移温度15℃以下の軟質重合体のセグメントを含む(1)~(3)のいずれかに記載の二次電池用多孔膜。
(5)前記ブロックポリマーが、前記二次電池用電解液に対する相溶性を示すセグメントを有し、前記二次電池用電解液に対する相溶性を示すセグメントが、溶解度パラメーター(SP)が8.0以上11未満である単量体成分、及び/または、親水性基を有する単量体成分を含む(1)~(4)のいずれかに記載の二次電池用多孔膜。
(6)前記ブロックポリマーが、前記二次電池用電解液に対する相溶性を示さないセグメントを有し、前記二次電池用電解液に対する相溶性を示さないセグメントが、溶解度パラメーターが8.0未満もしくは11以上である単量体成分、及び/または、疎水性部を有する単量体成分を含む(1)~(4)のいずれかに記載の二次電池用多孔膜。
(7)非導電性粒子、ブロックポリマー及び溶媒を含む二次電池多孔膜用スラリー。
(8)請求項7に記載の二次電池多孔膜用スラリーを基材に塗布し、次いで乾燥する工程を含む二次電池用多孔膜の製造方法。
(9)集電体、前記集電体上に設けられた、結着剤及び電極活物質を含む電極合剤層、及び前記電極合剤層上に設けられた、(1)~(6)のいずれかに記載の二次電池用多孔膜の層を含む二次電池用電極。
(10)有機セパレーター層、前記有機セパレーター層上に設けられた、(1)~(6)のいずれかに記載の二次電池用多孔膜を含む二次電池用セパレーター。
(11)正極、負極、セパレーター及びエチレンカーボネートとジエチルカーボネートを含有する二次電池用電解液を含む二次電池であって、前記正極、負極及びセパレーターの少なくともいずれかが、(1)~(6)のいずれかに記載の二次電池用多孔膜を含む、二次電池。
本発明の二次電池用多孔膜は、非導電性粒子及びブロックポリマーを含む。
本発明に用いる非導電性粒子は、リチウムイオン二次電池やニッケル水素二次電池などの使用環境下で安定に存在し、電気化学的にも安定であることが望まれる。例えば各種の無機粒子や有機粒子を使用することができる。電池の性能に悪影響を及ぼす金属のコンタミネーションが少ない粒子を低コストで製造できる点からは、有機粒子が好ましい。
無機粒子としては、酸化アルミニウム、酸化珪素、酸化マグネシウム、酸化チタン、BaTiO2、ZrO、アルミナ-シリカ複合酸化物等の酸化物粒子;窒化アルミニウム、窒化硼素等の窒化物粒子;シリコン、ダイヤモンド等の共有結合性結晶粒子;硫酸バリウム、フッ化カルシウム、フッ化バリウム等の難溶性イオン結晶粒子;タルク、モンモリロナイトなどの粘土微粒子等が用いられる。これらの粒子は必要に応じて元素置換、表面処理、固溶体化等されていてもよく、また単独でも2種以上の組合せからなるものでもよい。これらの中でも電解液中での安定性と電位安定性の観点から酸化物粒子であることが好ましい。
有機粒子としては、ポリスチレン、ポリエチレン、ポリイミド、メラミン樹脂、フェノール樹脂など各種高分子化合物からなる粒子等が用いられる。粒子を形成する上記高分子化合物は、混合物、変成体、誘導体、ランダム共重合体、交互共重合体、グラフト共重合体、ブロック共重合体、架橋体等であっても使用できる。有機粒子を形成する高分子化合物は、2種以上の高分子化合物の混合物であってもよい。
また、カーボンブラック、グラファイト、SnO2、ITO、金属粉末などの導電性金属及び導電性を有する化合物や酸化物の微粉末の表面を、非電気伝導性の物質で表面処理することによって、電気絶縁性を持たせて使用することも可能である。これらの非電気伝導性粒子は、2種以上併用して用いてもよい。
また、これらの粒子のBET比表面積は、粒子の凝集を抑制し、後述する多孔膜用スラリーの流動性を好適化する観点から具体的には、0.9~200m2/gであることが好ましく、1.5~150m2/gであることがより好ましい。
非導電性粒子が有機粒子である場合、該有機微粒子は高い耐熱性を有することが、多孔膜に耐熱性を賦与し電池の安定性を向上させる観点から好ましい。具体的には、熱天秤分析において昇温速度10℃/分で加熱したときに10重量%減量する温度が、好ましくは250℃以上、より好ましくは300℃以上、さらにより好ましくは350℃以上である。一方当該温度の上限は特に制限されないが、例えば450℃以下とすることができる。
非導電性粒子の粒子径分布(CV値)の下限は好ましくは0.5%以上であり、その上限は好ましくは40%以下であり、より好ましくは30%以下であり、さらにより好ましくは20%以下である。当該範囲内とすることにより、非導電性粒子層の空隙を埋めず、リチウムの移動を阻害し抵抗が増大することを抑制することができる。
本発明に用いるブロックポリマーは、2種のセグメントを有するブロック型ポリマーである。ブロックポリマーは、これら2種のセグメントを有するのに加え、さらに他の1種以上の任意のセグメントを有しうる。
好ましくは、ブロックポリマーは、前記二次電池用電解液に対する相溶性を示すセグメントと前記二次電池用電解液に対する相溶性を示さないセグメントとから構成される。より具体的なブロックポリマーの例としては、前記二次電池用電解液に対する相溶性を示すセグメントと前記二次電池用電解液に対する相溶性を示さないセグメントとから実質的になり、後述するセグメントA及びセグメントB以外の成分を含んでいないものを挙げることができる。
一方、セグメントが前記二次電池用電解液に対し相溶性を示さないとは、電解液中にてセグメントが広がりを示さないことを指し、前記二次電池用電解液に対するセグメントの膨潤度が0%以上、300%以下であることを指す。
本発明において、各セグメントの膨潤度は以下の方法で測定する。
セグメントAの構成成分からなる重合体及びセグメントBの構成成分からなる重合体をそれぞれ約0.1mm厚のフィルムに成形し、これを約2センチ角に切り取って重量(浸漬前重量)を測定する。その後、温度60℃の前記二次電池用電解液中で72時間浸漬する。浸漬したフィルムを引き上げ、前記二次電池用電解液をふき取った直後の重量(浸漬後重量)を測定し、(浸漬後重量)/(浸漬前重量)×100(%)の値を前記膨潤度とする。
前記二次電池用電解液としては、エチレンカーボネート(EC)とジエチルカーボネート(DEC)とをEC:DEC=1:2(容積比、ただしECは40℃での容積、DECは20℃での容積)で混合してなる混合溶媒にLiPF6を1モル/リットルの濃度で溶解させた溶液を用いる。
本発明に用いるブロックポリマーは、前記セグメントAとセグメントBからのみ構成されるABブロック構造(AB型、ABA型、BAB型)でも、他の任意成分を含有する構造でもよい。他の任意成分を含有する場合は、かかる任意成分がABブロック構造の末端に配位していても、ABブロック構造中に配位していても、いずれでもよい。
その中でも、特に末端の構造が電解液に対し相溶性を示す成分であるほうが、多孔膜が高い電解液含浸性と電解液保持性を有し、その多孔膜を有する二次電池が高い長期サイクル特性を示すことから好ましい。
セグメントAは、溶解度パラメーターが8.0以上11(cal/cm3)1/2未満である単量体成分、及び/または親水性基を有する単量体成分の単位を含むことが好ましい。かかる単量体成分を含むことにより、セグメントAの電解液に対する膨潤度を、組成により制御して、電解液に対する相溶性を示すセグメントとすることができる。
本願において、「単量体」又は「単量体成分」の文言は、その文脈に応じて、単量体組成物を構成する単量体であると解されるか、または、重合体を構成する、単量体に基づく重合単位であると解される。
δ=ΣG/V=dΣG/M
ΣG:分子引力定数Gの総計
V:比容
M:分子量
d:比重
低級ポリオキシアルキレン基含基を含有する単量体としては、ポリ(エチレンオキシド)等のポリ(アルキレンオキシド)などが挙げられる。
セグメントBは、溶解度パラメーターが8.0未満もしくは11以上である単量体成分、及び/または親水性基を有する単量体成分の単位を含んでなるものが好ましい。かかる単量体成分を含むことにより、セグメントBの電解液に対する膨潤度を、組成により制御して、電解液に対する相溶性を示さないセグメントとすることができる。膨潤度を、架橋により制御して、電解液に対する相溶性を示さないものにするためには、セグメントBは、後述する架橋性基を有する単量体成分の単位を含むことが好ましい。
中でもセグメントAが電解液に対する相溶性を示し、セグメントBが電解液に対する相溶性を示さない場合においては、セグメントAが、ガラス転移温度15℃以下の軟質重合体を構成するセグメントと同一のセグメントであることが好ましく、更に好ましくは、ガラス転移温度-5℃以下の軟質重合体を構成するセグメントと同一のセグメントであり、特に好ましくは、ガラス転移温度-40℃以下の軟質重合体を構成するセグメントと同一のセグメントである。セグメントAが、ガラス転移温度が上記範囲内である軟質重合体を構成するセグメントと同一のセグメントであることにより、ブロックポリマー中のセグメントBが活物質表面に吸着した状態で、セグメントAの可動性が増すため、低温でのリチウム受け入れ性が向上する。
なお、セグメントのガラス転移温度は、前記に例示した単量体の組み合わせ及び後述する共重合可能な単量体を更に組み合わせることによって調整可能である。
ブロックポリマーの架橋方法としては、加熱またはエネルギー線照射により架橋させる方法が挙げられる。加熱またはエネルギー線照射により架橋可能なブロックポリマーを架橋して用いることで、加熱条件やエネルギー線照射の照射条件(強度など)により架橋度を調節できる。また、架橋度が高いほど膨潤度が小さくなる傾向にあるので、架橋度を変えることにより膨潤度を調節することができる。
加熱またはエネルギー線照射により架橋可能なブロックポリマーとする方法としては、ブロックポリマー中に架橋性基を導入する方法や、架橋剤を併用する方法が挙げられる。
炭素-炭素二重結合およびエポキシ基を含有する単量体としては、たとえば、ビニルグリシジルエーテル、アリルグリシジルエーテル、ブテニルグリシジルエーテル、o-アリルフェニルグリシジルエーテルなどの不飽和グリシジルエーテル;ブタジエンモノエポキシド、クロロプレンモノエポキシド、4,5-エポキシ-2-ペンテン、3,4-エポキシ-1-ビニルシクロヘキセン、1,2-エポキシ-5,9-シクロドデカジエンなどのジエンまたはポリエンのモノエポキシド;3,4-エポキシ-1-ブテン、1,2-エポキシ-5-ヘキセン、1,2-エポキシ-9-デセンなどのアルケニルエポキシド;グリシジルアクリレート、グリシジルメタクリレート、グリシジルクロトネート、グリシジル-4-ヘプテノエート、グリシジルソルベート、グリシジルリノレート、グリシジル-4-メチル-3-ペンテノエート、3-シクロヘキセンカルボン酸のグリシジルエステル、4-メチル-3-シクロヘキセンカルボン酸のグリシジルエステルなどの不飽和カルボン酸のグリシジルエステル類;が挙げられる。
前記粒子状金属除去工程におけるポリマー溶液もしくはポリマー分散液から粒子状の金属成分を除去する方法は特に限定されず、例えば、濾過フィルターによる濾過により除去する方法、振動ふるいによる除去する方法、遠心分離により除去する方法、磁力により除去する方法等が挙げられる。中でも、除去対象が金属成分であるため磁力により除去する方法が好ましい。磁力により除去する方法としては、金属成分が除去できる方法であれば特に限定はされないが、生産性および除去効率を考慮すると、好ましくはブロックポリマーの製造ライン中に磁気フィルターを配置することで行われる。
本発明の二次電池用多孔膜を製造する方法としては、1)非導電性粒子、ブロックポリマー及び溶媒を含む多孔膜用スラリーを所定の基材上に塗布し、次いで乾燥する方法;2)非導電性粒子、ブロックポリマー及び溶媒を含む多孔膜用スラリーに、基材を浸漬後、これを乾燥する方法;3)非導電性粒子、ブロックポリマー及び溶媒を含む多孔膜用スラリーを、剥離フィルム上に塗布、成膜し、得られた多孔膜を所定の基材上に転写する方法;が挙げられる。この中でも、1)非導電性粒子、ブロックポリマー及び溶媒を含む多孔膜用スラリーを基材に塗布し、次いで乾燥する方法が、多孔膜の膜厚を制御しやすいことから最も好ましい。
本発明の二次電池多孔膜用スラリーは、非導電性粒子、ブロックポリマー、及び溶媒を含む。非導電性粒子、ブロックポリマーとしては、二次電池用多孔膜で説明したものと同様のものが挙げられる。
多孔膜用スラリーに用いる溶媒としては、水および有機溶媒のいずれも使用できる。有機溶媒としては、シクロペンタン、シクロヘキサンなどの環状脂肪族炭化水素類;トルエン、キシレン、エチルベンゼンなどの芳香族炭化水素類;アセトン、エチルメチルケトン、ジイソプロピルケトン、シクロヘキサノン、メチルシクロヘキサン、エチルシクロヘキサンなどのケトン類;メチレンクロライド、クロロホルム、四塩化炭素など塩素脂肪族炭化水素;芳酢酸エチル、酢酸ブチル、γ-ブチロラクトン、ε-カプロラクトンなどのエステル類;アセトニトリル、プロピオニトリルなどのアシロニトリル類;テトラヒドロフラン、エチレングリコールジエチルエーテルなどのエーテル類:メタノール、エタノール、イソプロパノール、エチレングリコール、エチレングリコールモノメチルエーテルなどのアルコール類;N-メチルピロリドン、N,N-ジメチルホルムアミドなどのアミド類があげられる。
これらの溶媒は、単独で使用しても、これらを2種以上混合して混合溶媒として使用してもよい。これらの中でも特に、非導電性粒子の分散性にすぐれ、沸点が低く揮発性が高い溶媒が、短時間でかつ低温で除去できるので好ましい。具体的には、アセトン、トルエン、シクロヘキサノン、シクロペンタン、テトラヒドロフラン、シクロヘキサン、キシレン、水、若しくはN-メチルピロリドン、またはこれらの混合溶媒が好ましい。
多孔膜用スラリーの製法は、特に限定はされず、上記非導電性粒子、ブロックポリマー、及び溶媒と必要に応じ添加される任意の成分を混合して得られる。
本発明においては上記成分を用いることにより混合方法や混合順序にかかわらず、非導電性粒子が高度に分散された多孔膜用スラリーを得ることができる。混合装置は、上記成分を均一に混合できる装置であれば特に限定されず、ボールミル、サンドミル、顔料分散機、擂潰機、超音波分散機、ホモジナイザー、プラネタリーミキサーなどを使用することができるが、中でも高い分散シェアを加えることができる、ビーズミル、ロールミル、フィルミックス等の高分散装置を使用することが特に好ましい。
多孔膜用スラリーの粘度は、均一塗工性、スラリー経時安定性の観点から、好ましくは10mPa・S~10,000mPa・S、更に好ましくは50~500mPa・sである。前記粘度は、B型粘度計を用いて25℃、回転数60rpmで測定した時の値である。
本発明の二次電池用多孔膜の製造方法においては、電極や有機セパレーター以外の基材上に形成してもよい。本発明の二次電池用多孔膜を、電極や有機セパレーター以外の基材上に形成した場合は、多孔膜を基材から剥離し、直接電池を組み立てる時に、電極上や有機セパレーター上に積層することにより使用することが出来る。
乾燥方法としては例えば温風、熱風、低湿風による乾燥、真空乾燥、(遠)赤外線や電子線などの照射による乾燥法が挙げられる。乾燥温度は、使用する溶媒の種類によってかえることができる。溶媒を完全に除去するために、例えば、N-メチルピロリドン等の揮発性の低い溶媒を用いる場合には送風式の乾燥機で120℃以上の高温で乾燥させることが好ましい。逆に揮発性の高い溶媒を用いる場合には100℃以下の低温において乾燥させることもできる。多孔膜を後述する有機セパレーター上に形成する際は、有機セパレーターの収縮を起こさずに乾燥させることが必要の為、100℃以下の低温での乾燥が好ましい。
本発明の二次電池用電極は、結着剤及び電極活物質を含んでなる電極合剤層が、集電体に付着してなり、かつ電極合剤層の表面に、前記多孔膜が積層されてなる。即ち、本発明の二次電池用電極は、集電体、前記集電体上に設けられた、結着剤及び電極活物質を含む電極合剤層、及び前記電極合剤層上に設けられた、前記本発明の二次電池用多孔膜の層を含む。
本発明の二次電池用電極に用いられる電極活物質は、電極が利用される二次電池に応じて選択すればよい。前記二次電池としては、リチウムイオン二次電池やニッケル水素二次電池が挙げられる。
無機化合物からなる正極活物質としては、遷移金属酸化物、リチウムと遷移金属との複合酸化物、遷移金属硫化物などが挙げられる。上記の遷移金属としては、Fe、Co、Ni、Mn等が使用される。正極活物質に使用される無機化合物の具体例としては、LiCoO2、LiNiO2、LiMnO2、LiMn2O4、LiFePO4、LiFeVO4などのリチウム含有複合金属酸化物;TiS2、TiS3、非晶質MoS2等の遷移金属硫化物;Cu2V2O3、非晶質V2O-P2O5、MoO3、V2O5、V6O13などの遷移金属酸化物が挙げられる。これらの化合物は、部分的に元素置換したものであってもよい。有機化合物からなる正極活物質としては、例えば、ポリアセチレン、ポリ-p-フェニレンなどの導電性高分子化合物を用いることもできる。電気伝導性に乏しい、鉄酸化物は、還元焼成時に炭素源物質を存在させることで、炭素材料で覆われた電極活物質として用いてもよい。また、これら化合物は、部分的に元素置換したものであってもよい。
本発明において、電極合剤層は、電極活物質の他に、結着剤を含む。結着剤を含むことにより電極中の電極合剤層の結着性が向上し、電極の撒回時等の工程上においてかかる機械的な力に対する強度が上がり、また電極中の電極合剤層が脱離しにくくなることから、脱離物による短絡等の危険性が小さくなる。
ポリブチルアクリレート、ポリブチルメタクリレート、ポリヒドロキシエチルメタクリレート、ポリアクリルアミド、ポリアクリロニトリル、ブチルアクリレート・スチレン共重合体、ブチルアクリレート・アクリロニトリル共重合体、ブチルアクリレート・アクリロニトリル・グリシジルメタクリレート共重合体などの、アクリル酸またはメタクリル酸誘導体の単独重合体またはそれと共重合可能な単量体との共重合体である、アクリル軟質重合体;
ポリイソブチレン、イソブチレン・イソプレンゴム、イソブチレン・スチレン共重合体などのイソブチレン軟質重合体;
ポリブタジエン、ポリイソプレン、ブタジエン・スチレンランダム共重合体、イソプレン・スチレンランダム共重合体、アクリロニトリル・ブタジエン共重合体、アクリロニトリル・ブタジエン・スチレン共重合体、ブタジエン・スチレン・ブロック共重合体、スチレン・ブタジエン・スチレン・ブロック共重合体、イソプレン・スチレン・ブロック共重合体、スチレン・イソプレン・スチレン・ブロック共重合体などジエン軟質重合体;
ジメチルポリシロキサン、ジフェニルポリシロキサン、ジヒドロキシポリシロキサンなどのケイ素含有軟質重合体;
液状ポリエチレン、ポリプロピレン、ポリ-1-ブテン、エチレン・α-オレフィン共重合体、プロピレン・α-オレフィン共重合体、エチレン・プロピレン・ジエン共重合体(EPDM)、エチレン・プロピレン・スチレン共重合体などのオレフィン軟質重合体;
ポリビニルアルコール、ポリ酢酸ビニル、ポリステアリン酸ビニル、酢酸ビニル・スチレン共重合体などビニル軟質重合体;
ポリエチレンオキシド、ポリプロピレンオキシド、エピクロルヒドリンゴムなどのエポキシ軟質重合体;
フッ化ビニリデンゴム、四フッ化エチレン-プロピレンゴムなどのフッ素含有軟質重合体;
天然ゴム、ポリペプチド、蛋白質、ポリエステル熱可塑性エラストマー、塩化ビニル熱可塑性エラストマー、ポリアミド熱可塑性エラストマーなどのその他の軟質重合体などが挙げられる。これらの軟質重合体は、架橋構造を有したものであってもよく、また、変性により官能基を導入したものであってもよい。
本発明の二次電池用セパレーターは、有機セパレーター層上に、前記二次電池用多孔膜が積層されてなる。即ち、本発明の二次電池用セパレーターは、有機セパレーター層、及び前記有機セパレーター層上に設けられた、前記本発明の二次電池用多孔膜を含む。
本発明に用いる有機セパレーター層としては、電子伝導性がなくイオン伝導性があり、有機溶媒の耐性が高い、孔径の微細な多孔質膜が用いられ、例えばポリオレフィン(ポリエチレン、ポリプロピレン、ポリブテン、ポリ塩化ビニル)、及びこれらの混合物あるいは共重合体等の樹脂からなる微多孔膜、ポリエチレンテレフタレート、ポリシクロオレフィン、ポリエーテルスルフォン、ポリアミド、ポリイミド、ポリイミドアミド、ポリアラミド、ポリシクロオレフィン、ナイロン、ポリテトラフルオロエチレン等の樹脂からなる微多孔膜またはポリオレフィンの繊維を織ったもの、またはその不織布、絶縁性物質粒子の集合体等が挙げられる。これらの中でも、前述の多孔膜用スラリーの塗工性が優れ、セパレーター全体の膜厚を薄くし電池内の活物質比率を上げて体積あたりの容量を上げることができるため、ポリオレフィンの樹脂からなる微多孔膜が好ましい。
有機セパレーター層の厚さは、通常0.5~40μm、好ましくは1~30μm、更に好ましくは1~10μmである。この範囲であると電池内でのセパレーターによる抵抗が小さくなり、また有機セパレーター層への塗工時の作業性が良い。
本発明の二次電池は、正極、負極、セパレーター及び電解液を含み、前記正極、負極及びセパレーターの少なくともいずれかに、前記多孔膜が積層されてなる。即ち、本発明の二次電池は、正極、負極、セパレーター及び電解液を含む二次電池であって、前記正極、負極及びセパレーターの少なくともいずれかが、前記本発明の二次電池用多孔膜を含む。
リチウムイオン二次電池用の電解液としては、有機溶媒に支持電解質を溶解した有機電解液が用いられる。支持電解質としては、リチウム塩が用いられる。リチウム塩としては、特に制限はないが、LiPF6、LiAsF6、LiBF4、LiSbF6、LiAlCl4、LiClO4、CF3SO3Li、C4F9SO3Li、CF3COOLi、(CF3CO)2NLi、(CF3SO2)2NLi、(C2F5SO2)NLiなどが挙げられる。中でも、溶媒に溶けやすく高い解離度を示すLiPF6、LiClO4、CF3SO3Liが好ましい。これらは、二種以上を併用してもよい。解離度の高い支持電解質を用いるほどリチウムイオン伝導度が高くなるので、支持電解質の種類によりリチウムイオン伝導度を調節することができる。
また前記電解液には添加剤を含有させて用いることも可能である。添加剤としては前述の電極合剤層スラリー中に使用されるビニレンカーボネート(VC)などのカーボネートの化合物が挙げられる。
上記以外の電解液としては、ポリエチレンオキシド、ポリアクリロニトリルなどのポリマー電解質や前記ポリマー電解質に電解液を含浸したゲル状ポリマー電解質や、LiI、Li3Nなどの無機固体電解質を挙げることができる。
本発明の二次電池において、多孔膜が積層されてなる正極や負極としては、前記二次電池用電極を正極や負極として用いればよく、多孔膜が積層されてなるセパレーターとしては、前記二次電池用セパレーターをセパレーターとして用いればよい。
実施例および比較例において、各種物性は以下のように評価した。
直径1cmの試験管内に深さ5cmまで多孔膜用スラリーを入れ、試験サンプルとする。1種の試料の測定につき5本の試験サンプルを調製する。前記試験サンプルを机上に垂直に設置する。設置した多孔膜用スラリーの状態を10日間観測し、下記の基準により判定する。5本のサンプルでの沈降に有するまでにかかる時間・日数(平均沈降所要時間(日数)という)をそれぞれもとめ、それらの平均沈降所要時間(日数)を沈降が見られた日とする。2相分離が見られないほど分散性に優れることを示す。
A:10日後にも沈降がみられない。
B:6~10日後に沈降がみられる。
C:24時間以上~5日以内に沈降がみられる。
D:10時間以上、24時間未満に沈降がみられる。
E:3時間以上、10時間未満に沈降がみられる。
F:3時間未満に沈降が見られる。
得られたフルセルコイン型電池を、25℃で0.1Cの定電流法によって4.3Vまで充電しその後0.1Cにて3.0Vまで放電し、0.1C放電容量を求める。その後、0.1Cにて4.3Vまで充電しその後20Cにて3.0Vまで放電し、20C放電容量を求める。これらの測定をフルセルコイン型電池10セルについて行う。10セルの0.1C放電容量の平均値、及び10セルの20C放電容量の平均値を求めそれぞれa及びbとする。20C放電容量bと0.1C放電容量aの電気容量の比((b/a)×100(単位:%))で表される容量保持率を求め、これを出力特性の評価基準とし、以下の基準により判定する。この値が高いほど出力特性に優れている。
A:50%以上
B:40%以上50%未満
C:20%以上40%未満
D:1%以上20%未満
E:1%未満
得られたフルセルコイン型電池を、25℃で0.1Cで3Vから4.3Vまで充電し、次いで0.1Cで4.3Vから3Vまで放電する充放電を、100サイクル繰り返し、5サイクル目の0.1C放電容量に対する100サイクル目の0.1C放電容量の割合を百分率で算出した値を容量維持率とし、下記の基準で判断した。この値が大きいほど放電容量減が少なく、サイクル特性に優れている。
A:70%以上
B:60%以上70%未満
C:50%以上60%未満
D:40%以上50%未満
E:30%以上40%未満
F:30%未満
得られたラミネートセル型電池を、それぞれ25℃で充放電レートを0.1Cとし、定電流定電圧充電法にて、4.2Vになるまで定電流で充電し、定電圧で充電する。その後0.1Cにて3.0Vまで放電し、25℃での放電容量を求める。その後、-20℃に設定した恒温槽内で0.1Cで定電流定電圧充電を行った。25℃での電池容量をa、-20℃での電池容量をbとする。-20℃での電池容量bと25℃での電池容量aの電気容量の比(b/a(%))で表される低温容量保持率を求め、これを低温特性の指標とした。この値が大きいほど、低温でのリチウム受け入れ性がよい電池であることを示す。
<ブロックポリマーの合成>
メカニカルスターラー、窒素導入口、冷却管およびラバーセプタムを備えた4つ口フラスコに、スチレン40部を入れた後、これに2,2´-ビピリジン1.3部を所定量加えてから、系内を窒素置換した。これに窒素気流下、臭化銅0.41部を加えた後、反応系を90℃に加熱し、開始剤として、2-ブロモ-2-メチルプロピオン酸2-ヒドロキシエチルを0.6部加えて重合を開始させ、溶剤を加えずに、窒素気流下で、90℃で9時間重合させた。重合率(加熱し揮発成分を除去したポリマー重量を、揮発成分を除去する前の重合液そのままのポリマー重量で割った値で定義される割合)が80%以上であることを確認した後、これにアクリル酸n-ブチル60部をラバーセプタムから添加し、これをさらに110℃で12時間加熱した。このようにして、スチレン-アクリル酸ブチルのブロックポリマーを含む混合物が得られた。得られたブロックポリマーを含む混合物を、120℃に加熱して、20000Gの遠心力で1時間遠心処理し、ブロックポリマーの粗精製物(緑色である)を、上澄として得た。このブロックポリマーの粗精製物100部にスルホン酸型カチオン交換樹脂10部を加えて、120℃で2時間撹拌した後、当該イオン交換樹脂を除去し、さらに重合触媒等を除去して、無色透明なスチレンに基づく重合単位含量約40%の重合体-1を得た。得られた重合体-1の組成、比率、重量平均分子量、及びガラス転移温度を表1に示す。ガラス移転温度は、示差走査熱量法(DSC法)により、示差走査熱量分析(セイコーインスツルメンツ社製、製品名「EXSTAR6000」)で-120℃から120℃まで20℃/分の昇温速度で測定した。重量平均分子量は重合体-1をテトラヒドロフランに溶解して、0.2重量%溶液とした後、0.45μmのメンブランフィルターで濾過し、測定試料として、ゲルパーミエーションクロマトグラフィ(GPC)を用いて下記条件にて測定し、標準ポリスチレン換算の重量平均分子量を求めた。
(測定条件)
測定装置:HLC-8220GPC(東ソー社製)
カラム:TSKgel Multipore HXL-M(東ソー社製)
溶離液:テトラヒドロフラン(THF)
溶離速度:0.3ml/分
検知器:RI(極性(+))
カラム温度:40℃
得られた重合体-1をN-メチル-2-ピロリドン(以下NMPという。)に溶解し、固形分濃度20%の重合体-1のNMP溶液を得た。
非導電性粒子(酸化アルミニウム、平均粒径0.3μm、鉄含有量<20ppm)と、重合体-1の溶液とを、100:2.5の含有割合(固形分相当比)となるように混合し、更にNMPを固形分濃度が30%になるように混合させてビーズミルを用いて分散させ多孔膜用スラリー1を調製した。得られた多孔膜用スラリーの分散性を測定した。結果を表2に示す。
負極活物質として粒子径20μm、比表面積4.2m2/gのグラファイト98部と、結着剤としてPVDF(ポリフッ化ビニリデン)を固形分相当で5部とを混合し、更にN-メチルピロリドンを加えてプラネタリーミキサーで混合してスラリー状の負極用電極組成物(負極合剤層形成用スラリー)を調製した。この負極用電極組成物を厚さ10μmの銅箔の片面に塗布し、110℃で3時間乾燥した後、ロールプレスして厚さ60μmの負極合剤層を有する負極を得た。
正極活物質としてスピネル構造を有するマンガン酸リチウム92部と、アセチレンブラック5部、結着剤としてPVDF(ポリフッ化ビニリデン)を固形分相当で3部とを加え、さらにNMPで固形分濃度87%に調整した後にプラネタリーミキサーで60分混合した。さらにNMPで固形分濃度84%に調整した後に10分間混合してスラリー状の正極用電極組成物(正極合剤層形成用スラリー)を調製した。この正極用電極組成物を厚さ18μmのアルミニウム箔に塗布し、120℃で3時間乾燥した後、ロールプレスして厚さ50μmの正極合剤層を有する正極を得た。
得られた負極の、負極合剤層側の面上に、前記多孔膜用スラリー1を乾燥後の多孔膜層の厚さが5μmになるようにワイヤーバーを用いて塗工し、次いで90℃で10分間乾燥することにより、多孔膜を形成し、(銅箔)/(負極合剤層)/(多孔膜)の層構成を有する多孔膜付負極1を得た。
次いで、得られた正極を直径13mmの円形に切り抜いた。得られた多孔膜付負極1を直径14mmの円形に切り抜いた。厚さ25μmの乾式法により製造された単層のポリプロピレン製セパレーター(気孔率55%)を直径18mmの円形に切り抜いた。これらを、ポリプロピレン製パッキンを設置したステンレス鋼製のコイン型外装容器(直径20mm、高さ1.8mm、ステンレス鋼厚さ0.25mm)中に収納した。これらの円形の電極及びセパレーターの配置は、下記の通りとした。円形の正極は、そのアルミニウム箔が外装容器底面に接触するよう配置した。円形のセパレーターは、円形の正極と円形の多孔膜付負極1との間に介在するよう配置した。円形の多孔膜付負極1は、その多孔膜側の面が、円形のセパレーターを介して円形の正極の合剤層側の面に対向するよう配置した。更に負極の銅箔上にエキスパンドメタルを載置し、この容器中に電解液(EC/DEC=1/2、1M LiPF6)を空気が残らないように注入し、ポリプロピレン製パッキンを介して外装容器に厚さ0.2mmのステンレス鋼のキャップをかぶせて固定し、電池缶を封止して、直径20mm、厚さ約3.2mmのフルセル型コインセルを製造した(コインセルCR2032)。得られた電池について出力特性、サイクル特性を測定した。結果を表2に示す。
アルミニウムシートと、その両面を被覆するポリプロピレンからなる樹脂とからなるラミネートフィルムを用いて電池容器を作成した。次いで、上記で得た正極および多孔膜付負極それぞれの端部から合剤層及び多孔膜を除去し、銅箔又はアルミニウム箔が露出した箇所を形成した。正極のアルミニウム箔が露出した箇所にNiタブを、負極の銅箔が露出した箇所にCuタブを溶接した。得られたタブ付きの正極及びタブ付きの多孔膜付負極を、ポリエチレン製の微多孔膜からなるセパレータを挟んで重ねた。電極の面は、正極の合剤層側の面と多孔膜付負極の多孔膜側の面とが対向する向きに配置した。重ねた電極及びセパレーターを、捲回して上記の電池容器に収納した。続いてここに、エチレンカーボネートとジエチルカーボネートを25℃で体積比で1:2で混合した混合溶媒に、LiPF6を1モル/リットルの濃度になるように溶解させた電解液を注入した。次いで、ラミネートフィルムを封止させて本発明のリチウムイオン二次電池であるラミネートセルを作製した。得られた電池について、低温特性を測定した。評価結果を表3に示す。
多孔膜を構成する結着剤として重合体-1のかわりに表1に示す組成からなる重合体-2~4を用いた(即ち、セグメントAを構成する単量体及びセグメントBを構成する単量体として、アクリル酸n-ブチル及びスチレンに代えて、それぞれ表1において構造「A」及び「B」として示す種類の単量体を用いた他は、実施例1の<ブロックポリマーの合成>と同様にして、重合体-2~4を得、これを用いた)他は、実施例1と同様に多孔膜用スラリー、多孔膜付電極、及び電池を作製した。そして、得られた多孔膜用スラリーの分散性、得られた電池の出力特性、サイクル特性を評価した。結果を表2に示す。
<ブロックポリマーの合成>
スチレンを加えた際の重合時間を9時間から36時間に変更し、アクリル酸n-ブチルを加えた際の重合時間を12時間から48時間に変更した他は、実施例1と同様にブロックポリマーを合成し、重合体-5を得た。即ち、フラスコにスチレン及び他の物質(開始剤等)を入れた後の90℃における重合反応の時間を9時間から36時間に変更した。また、反応混合物にアクリル酸n-ブチル60部を添加した後の110℃に加熱する時間を12時間から48時間に変更した。得られた重合体-5の組成、比率、重量平均分子量、及びガラス転移温度を表1に示す。
実施例1において、多孔膜を構成する結着剤として重合体-1のかわりに重合体-5を用いた他は、実施例1と同様に多孔膜用スラリー、多孔膜付電極、及び電池を作製した。そして、得られた多孔膜用スラリーの分散性、得られた電池の出力特性、サイクル特性を評価した。結果を表2に示す。
<ブロックポリマーの合成>
スチレンを加えた際の重合時間を9時間から1時間に変更し、アクリル酸n-ブチルを加えた際の重合時間を12時間から2時間に変更した他は、実施例1と同様にブロックポリマーを合成し、重合体-6を得た。即ち、フラスコにスチレン及び他の物質(開始剤等)を入れた後の90℃における重合反応の時間を9時間から1時間に変更した。また、反応混合物にアクリル酸n-ブチル60部を添加した後の110℃に加熱する時間を12時間から2時間に変更した。得られた重合体-6の組成、比率、重量平均分子量、及びガラス転移温度を表1に示す。
実施例1において、多孔膜を構成する結着剤として重合体-1のかわりに重合体-6を用いた他は、実施例1と同様に多孔膜用スラリー、多孔膜付電極、及び電池を作製した。そして、得られた多孔膜用スラリーの分散性、得られた電池の出力特性、サイクル特性を評価した。結果を表2に示す。
<ブロックポリマーの合成>
スチレンの添加量を40部から20部に変更し、アクリル酸n-ブチルの添加量を60部から80部に変更し、スチレンを加えた際の重合時間を9時間から6時間に変更し(即ち、フラスコにスチレン及び他の物質(開始剤等)を入れた後の90℃における重合反応の時間を9時間から6時間に変更した)、アクリル酸n-ブチルを加えた際の重合時間を12時間から20時間に変更した(即ち、反応混合物にアクリル酸n-ブチル60部を添加した後の110℃に加熱する時間を12時間から20時間に変更した)他は、実施例1と同様にブロックポリマーを合成し、重合体-7を得た。得られた重合体-7の組成、比率、重量平均分子量、及びガラス転移温度を表1に示す。
実施例1において、多孔膜を構成する結着剤として重合体-1のかわりに重合体-7を用いた他は、実施例1と同様に多孔膜用スラリー、多孔膜付電極、及び電池を作製した。そして、得られた多孔膜用スラリーの分散性、得られた電池の出力特性、サイクル特性を評価した。結果を表2に示す。
<ブロックポリマーの合成>
スチレンの添加量を40部から80部に変更し、アクリル酸n-ブチルの添加量を20部から80部に変更し、スチレンを加えた際の重合時間を9時間から14時間に変更し(即ち、フラスコにスチレン及び他の物質(開始剤等)を入れた後の90℃における重合反応の時間を9時間から14時間に変更した)、アクリル酸n-ブチルを加えた際の重合時間を12時間から8時間に変更した(即ち、反応混合物にアクリル酸n-ブチル60部を添加した後の110℃に加熱する時間を12時間から8時間に変更した)他は、実施例1と同様にブロックポリマーを合成し、重合体-8を得た。得られた重合体-8の組成、比率、重量平均分子量、及びガラス転移温度を表1に示す。
実施例1において、多孔膜を構成する結着剤として重合体-1のかわりに重合体-8を用いた他は、実施例1と同様に多孔膜用スラリー、多孔膜付電極、及び電池を作製した。そして、得られた多孔膜用スラリーの分散性、得られた電池の出力特性、サイクル特性を評価した。結果を表2に示す。
多孔膜を構成する結着剤として重合体-1のかわりに表1に示す組成からなる重合体-9~10を用いた(即ち、セグメントAを構成する単量体及びセグメントBを構成する単量体として、アクリル酸n-ブチル及びスチレンに代えて、それぞれ表1において構造「A」及び「B」として示す種類の単量体を用いた他は、実施例1の<ブロックポリマーの合成>と同様にして、重合体-9~10を得、これを用いた)他は、実施例1と同様に多孔膜用スラリー、多孔膜付電極、及び電池を作製した。そして、得られた多孔膜用スラリーの分散性、得られた電池の出力特性、サイクル特性、低温特性を評価した。結果を表2及び表3に示す。
<多孔膜用スラリーの作成>
非導電性粒子(酸化アルミニウム、平均粒径0.3μm、鉄含有量<20ppm)と、重合体-3の溶液とを、100:2.5の含有割合(固形分相当比)となるように混合し、更にNMPを固形分濃度が30%になるように混合させてビーズミルを用いて分散させ多孔膜用スラリー11を調製した。得られた多孔膜用スラリーの分散性を測定した。結果を表2に示す。
負極活物質として粒子径20μm、比表面積4.2m2/gのグラファイト98部と、結着剤としてPVDF(ポリフッ化ビニリデン)を固形分相当で5部とを混合し、更にN-メチルピロリドンを加えてプラネタリーミキサーで混合してスラリー状の負極用電極組成物(負極合剤層形成用スラリー)を調製した。この負極用電極組成物を厚さ10μmの銅箔の片面に塗布し、110℃で3時間乾燥した後、ロールプレスして厚さ60μmの負極合剤層を有する負極11を得た。
正極活物質としてスピネル構造を有するマンガン酸リチウム92部と、アセチレンブラック5部、結着剤としてPVDF(ポリフッ化ビニリデン)を固形分相当で3部とを加え、さらにNMPで固形分濃度87%に調整した後にプラネタリーミキサーで60分混合した。さらにNMPで固形分濃度84%に調整した後に10分間混合してスラリー状の正極用電極組成物(正極合剤層形成用スラリー)を調製した。この正極用電極組成物を厚さ18μmのアルミニウム箔に塗布し、120℃で3時間乾燥した後、ロールプレスして厚さ50μmの正極合剤層を有する正極11を得た。
厚さ25μmの乾式法により製造された単層のポリプロピレン製セパレーター(気孔率55%)の一方の面上に、前記多孔膜用スラリー11を乾燥後の多孔膜層の厚さが5μmになるようにワイヤーバーを用いて塗工し、次いで90℃で10分間乾燥し片面に多孔膜を形成した。さらに、セパレーターのもう一方の面に対しても同様に乾燥後の多孔膜層の厚さが5μmになるようにワイヤーバーを用いて塗工し、次いで90℃で10分間乾燥することにより、両面に多孔膜を形成し、多孔膜付セパレーターを得た。
次いで、正極11を直径13mmの円形に切り抜いた。負極11を直径14mmの円形に切り抜いた。多孔膜付セパレーターを直径18mmの円形に切り抜いた。これらを、ポリプロピレン製パッキンを設置したステンレス鋼製のコイン型外装容器(直径20mm、高さ1.8mm、ステンレス鋼厚さ0.25mm)中に収納した。これらの円形の電極及びセパレーターの配置は、下記の通りとした。円形の正極は、そのアルミニウム箔が外装容器底面に接触するよう配置した。円形のセパレーターは、円形の正極と円形の負極との間に介在するよう配置した。円形の負極は、その合剤層側の面が、円形のセパレーターを介して円形の正極の合剤層側の面に対向するよう配置した。更に負極の銅箔上にエキスパンドメタルを載置し、この容器中に電解液(EC/DEC=1/2、1M LiPF6)を空気が残らないように注入し、ポリプロピレン製パッキンを介して外装容器に厚さ0.2mmのステンレス鋼のキャップをかぶせて固定し、電池缶を封止して、直径20mm、厚さ約3.2mmのフルセル型コインセルを製造した(コインセルCR2032)。得られた電池について出力特性、サイクル特性を測定した。結果を表2に示す。
<多孔膜用スラリーの作成>
重合体-3をアセトンに溶解し、固形分濃度20%の重合体-3のアセトン溶液を得た。
非導電性粒子(架橋MMA(積水化成工業社製SSX-101、平均粒子径1.0μm))と、重合体-3のアセトン溶液とを、100:2.5の含有割合(固形分相当比)となるように混合し、更にアセトンを固形分濃度が30%になるように混合させてビーズミルを用いて分散させ多孔膜用スラリー12を調製した。得られた多孔膜用スラリーの分散性を測定した。結果を表2に示す。
多孔膜用スラリーとして多孔膜用スラリー1のかわりに多孔膜用スラリー12を用いた他は、実施例1と同様に多孔膜用スラリー、多孔膜付電極、及び電池を作製した。そして、得られた多孔膜用スラリーの分散性、得られた電池の出力特性、サイクル特性、低温特性を評価した。結果を表2及び表3に示す。
<多孔膜用スラリーの作成>
非導電性粒子(酸化アルミニウム、平均粒径0.3μm、鉄含有量<20ppm)と、重合体-3の溶液(固形分濃度20%のNMP溶液)と、ポリフッ化ビニリデンの10%NMP溶液とを、100:1.25:1.25の含有割合(固形分相当比)となるように混合し、更にNMPを固形分濃度が30%になるように混合させてビーズミルを用いて分散させ多孔膜用スラリー13を調製した。得られた多孔膜用スラリーの分散性を測定した。結果を表2に示す。
多孔膜用スラリーとして多孔膜用スラリー1のかわりに多孔膜用スラリー13を用いた他は、実施例1と同様に多孔膜用スラリー、多孔膜付電極、及び電池を作製した。そして、得られた多孔膜用スラリーの分散性、得られた電池の出力特性、サイクル特性、低温特性を評価した。結果を表2及び表3に示す。
多孔膜を構成する結着剤として重合体-1のかわりにポリフッ化ビニリデン(ガラス転移点温度が-40℃)を用いた他は、実施例1と同様に多孔膜用スラリー、多孔膜付電極、及び電池を作製した。そして、得られた多孔膜用スラリーの分散性、得られた電池の出力特性、サイクル特性を評価した。結果を表2に示す。
多孔膜を構成する結着剤として重合体-1のかわりにスチレン-ブタジエン共重合体(ガラス転移点温度が-15℃)を用いた他は、実施例1と同様に多孔膜用スラリー、多孔膜付電極、及び電池を作製した。そして、得られた多孔膜用スラリーの分散性、得られた電池の出力特性、サイクル特性を評価した。結果を表2に示す。
多孔膜を構成する結着剤として重合体-1のかわりにアクリル酸n-ブチル-スチレン共重合体(ガラス転移点温度が5℃)を用いた他は、実施例1と同様に多孔膜用スラリー、多孔膜付電極、及び電池を作製した。そして、得られた多孔膜用スラリーの分散性、得られた電池の出力特性、サイクル特性を評価した。結果を表2に示す。
一方、結着剤としてブロック構造を有さない重合体を用いた比較例1~3は、多孔膜用スラリーの分散性、電池の出力特性、サイクル特性の全てにおいて劣っており、特にサイクル特性が著しく劣る。
Claims (11)
- 非導電性粒子及びブロックポリマーを含む二次電池用多孔膜。
- 前記ブロックポリマーが、エチレンカーボネートとジエチルカーボネートを含有する二次電池用電解液に対する相溶性を示すセグメントと前記二次電池用電解液に対する相溶性を示さないセグメントとである2つのセグメントを有する請求項1に記載の二次電池用多孔膜。
- 前記ブロックポリマーの重量平均分子量が、1,000~500,000の範囲にある請求項1に記載の二次電池用多孔膜。
- 前記ブロックポリマーが、ガラス転移温度15℃以下の軟質重合体のセグメントを含む請求項1に記載の二次電池用多孔膜。
- 前記ブロックポリマーが、前記二次電池用電解液に対する相溶性を示すセグメントを有し、前記二次電池用電解液に対する相溶性を示すセグメントが、溶解度パラメーター(SP)が8.0以上11未満である単量体成分、及び/または、親水性基を有する単量体成分を含む請求項1に記載の二次電池用多孔膜。
- 前記ブロックポリマーが、前記二次電池用電解液に対する相溶性を示さないセグメントを有し、前記二次電池用電解液に対する相溶性を示さないセグメントが、溶解度パラメーターが8.0未満もしくは11以上である単量体成分、及び/または、疎水性部を有する単量体成分を含む請求項1に記載の二次電池用多孔膜。
- 非導電性粒子、ブロックポリマー及び溶媒を含む二次電池多孔膜用スラリー。
- 請求項7に記載の二次電池多孔膜用スラリーを基材に塗布し、次いで乾燥する工程を含む二次電池用多孔膜の製造方法。
- 集電体、
前記集電体上に設けられた、結着剤及び電極活物質を含む電極合剤層、及び
前記電極合剤層上に設けられた、請求項1に記載の二次電池用多孔膜の層
を含む二次電池用電極。 - 有機セパレーター層、及び
前記有機セパレーター層上に設けられた、請求項1に記載の二次電池用多孔膜
を含む二次電池用セパレーター。 - 正極、負極、セパレーター及び電解液を含む二次電池であって、前記正極、負極及びセパレーターの少なくともいずれかが、請求項1に記載の二次電池用多孔膜を含む、二次電池。
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2011524761A JP5598472B2 (ja) | 2009-07-29 | 2010-07-26 | 二次電池用多孔膜及び二次電池 |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2009176641 | 2009-07-29 | ||
JP2009-176641 | 2009-07-29 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2011013604A1 true WO2011013604A1 (ja) | 2011-02-03 |
Family
ID=43529259
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2010/062499 WO2011013604A1 (ja) | 2009-07-29 | 2010-07-26 | 二次電池用多孔膜及び二次電池 |
Country Status (3)
Country | Link |
---|---|
JP (1) | JP5598472B2 (ja) |
KR (1) | KR20120051653A (ja) |
WO (1) | WO2011013604A1 (ja) |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2013125645A1 (ja) * | 2012-02-23 | 2013-08-29 | 日本ゼオン株式会社 | 二次電池用多孔膜、二次電池用電極、二次電池用セパレーター及び二次電池 |
WO2013141140A1 (ja) * | 2012-03-22 | 2013-09-26 | 日本ゼオン株式会社 | 二次電池用多孔膜及びその製造方法、二次電池用電極、二次電池用セパレーター並びに二次電池 |
CN103563130A (zh) * | 2011-06-02 | 2014-02-05 | 协立化学产业株式会社 | 电池电极或隔板用涂布剂组合物 |
KR20140116415A (ko) * | 2012-01-19 | 2014-10-02 | 실 게엠베하 | 다공성 층을 포함하는 세퍼레이터 및 상기 세퍼레이터를 제조하는 방법 |
KR20140144182A (ko) * | 2012-03-28 | 2014-12-18 | 제온 코포레이션 | 2 차 전지용 다공막 및 그 제조 방법, 2 차 전지용 전극, 2 차 전지용 세퍼레이터 그리고 2 차 전지 |
WO2019039560A1 (ja) * | 2017-08-24 | 2019-02-28 | 日本ゼオン株式会社 | 非水系二次電池用バインダー組成物、非水系二次電池機能層用スラリー組成物、非水系二次電池用機能層、非水系二次電池用電池部材、および非水系二次電池 |
WO2019107229A1 (ja) * | 2017-11-30 | 2019-06-06 | 日本ゼオン株式会社 | 非水系二次電池用バインダー組成物、非水系二次電池機能層用スラリー組成物、非水系二次電池用機能層、非水系二次電池用電池部材および非水系二次電池 |
CN111902980A (zh) * | 2018-04-03 | 2020-11-06 | 日本瑞翁株式会社 | 非水系二次电池功能层用组合物、非水系二次电池构件以及非水系二次电池 |
WO2020257425A1 (en) * | 2019-06-19 | 2020-12-24 | Arkema Inc. | Reticulated composite material |
WO2021200083A1 (ja) * | 2020-03-31 | 2021-10-07 | 日本ゼオン株式会社 | 電気化学素子機能層用組成物、電気化学素子用積層体、および電気化学素子 |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20190386336A1 (en) | 2017-03-17 | 2019-12-19 | Zeon Corporation | Composition for non-aqueous secondary battery functional layer, functional layer for non-aqueous secondary battery, non-aqueous secondary battery, and method of manufacturing the non-aqueous secondary battery |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005353584A (ja) * | 2004-05-14 | 2005-12-22 | Matsushita Electric Ind Co Ltd | リチウムイオン二次電池とその製造法 |
JP2008503049A (ja) * | 2004-07-07 | 2008-01-31 | エルジー・ケム・リミテッド | 有機無機複合多孔性フィルム及びこれを用いる電気化学素子 |
JP2008053206A (ja) * | 2006-03-17 | 2008-03-06 | Sanyo Electric Co Ltd | 非水電解質電池及びその製造方法 |
WO2008108583A1 (en) * | 2007-03-07 | 2008-09-12 | Lg Chem, Ltd. | Organic/inorganic composite separator and electrochemical device containing the same |
-
2010
- 2010-07-26 KR KR1020127002047A patent/KR20120051653A/ko not_active Application Discontinuation
- 2010-07-26 JP JP2011524761A patent/JP5598472B2/ja active Active
- 2010-07-26 WO PCT/JP2010/062499 patent/WO2011013604A1/ja active Application Filing
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005353584A (ja) * | 2004-05-14 | 2005-12-22 | Matsushita Electric Ind Co Ltd | リチウムイオン二次電池とその製造法 |
JP2008503049A (ja) * | 2004-07-07 | 2008-01-31 | エルジー・ケム・リミテッド | 有機無機複合多孔性フィルム及びこれを用いる電気化学素子 |
JP2008053206A (ja) * | 2006-03-17 | 2008-03-06 | Sanyo Electric Co Ltd | 非水電解質電池及びその製造方法 |
WO2008108583A1 (en) * | 2007-03-07 | 2008-09-12 | Lg Chem, Ltd. | Organic/inorganic composite separator and electrochemical device containing the same |
Cited By (26)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103563130A (zh) * | 2011-06-02 | 2014-02-05 | 协立化学产业株式会社 | 电池电极或隔板用涂布剂组合物 |
EP2717353A4 (en) * | 2011-06-02 | 2015-03-18 | Kyoritsu Chemical Co Ltd | COATING COMPOSITION FOR BATTERY ELECTRODES OR SEPARATORS |
JP2015504234A (ja) * | 2012-01-19 | 2015-02-05 | ジール ゲーエムベーハーSihl GmbH | 多孔層を含むセパレータおよび前記のセパレータを製造するための方法 |
KR20140116415A (ko) * | 2012-01-19 | 2014-10-02 | 실 게엠베하 | 다공성 층을 포함하는 세퍼레이터 및 상기 세퍼레이터를 제조하는 방법 |
CN104115306A (zh) * | 2012-01-19 | 2014-10-22 | Sihl股份有限公司 | 包含多孔层的分离器和制作所述分离器的方法 |
KR102014566B1 (ko) * | 2012-01-19 | 2019-08-26 | 실 게엠베하 | 다공성 층을 포함하는 세퍼레이터 및 상기 세퍼레이터를 제조하는 방법 |
US9997755B2 (en) | 2012-01-19 | 2018-06-12 | Sihl Gmbh | Separator comprising a porous layer and method for producing said separator |
JPWO2013125645A1 (ja) * | 2012-02-23 | 2015-07-30 | 日本ゼオン株式会社 | 二次電池用多孔膜、二次電池用電極、二次電池用セパレーター及び二次電池 |
WO2013125645A1 (ja) * | 2012-02-23 | 2013-08-29 | 日本ゼオン株式会社 | 二次電池用多孔膜、二次電池用電極、二次電池用セパレーター及び二次電池 |
WO2013141140A1 (ja) * | 2012-03-22 | 2013-09-26 | 日本ゼオン株式会社 | 二次電池用多孔膜及びその製造方法、二次電池用電極、二次電池用セパレーター並びに二次電池 |
JPWO2013141140A1 (ja) * | 2012-03-22 | 2015-08-03 | 日本ゼオン株式会社 | 二次電池用多孔膜及びその製造方法、二次電池用電極、二次電池用セパレーター並びに二次電池 |
KR20140144182A (ko) * | 2012-03-28 | 2014-12-18 | 제온 코포레이션 | 2 차 전지용 다공막 및 그 제조 방법, 2 차 전지용 전극, 2 차 전지용 세퍼레이터 그리고 2 차 전지 |
KR101996361B1 (ko) | 2012-03-28 | 2019-07-04 | 제온 코포레이션 | 2 차 전지용 다공막 및 그 제조 방법, 2 차 전지용 전극, 2 차 전지용 세퍼레이터 그리고 2 차 전지 |
WO2019039560A1 (ja) * | 2017-08-24 | 2019-02-28 | 日本ゼオン株式会社 | 非水系二次電池用バインダー組成物、非水系二次電池機能層用スラリー組成物、非水系二次電池用機能層、非水系二次電池用電池部材、および非水系二次電池 |
WO2019107229A1 (ja) * | 2017-11-30 | 2019-06-06 | 日本ゼオン株式会社 | 非水系二次電池用バインダー組成物、非水系二次電池機能層用スラリー組成物、非水系二次電池用機能層、非水系二次電池用電池部材および非水系二次電池 |
CN111418098A (zh) * | 2017-11-30 | 2020-07-14 | 日本瑞翁株式会社 | 非水系二次电池用粘结剂组合物、非水系二次电池功能层用浆料组合物、非水系二次电池用功能层、非水系二次电池用电池构件及非水系二次电池 |
JPWO2019107229A1 (ja) * | 2017-11-30 | 2020-12-10 | 日本ゼオン株式会社 | 非水系二次電池用バインダー組成物、非水系二次電池機能層用スラリー組成物、非水系二次電池用機能層、非水系二次電池用電池部材および非水系二次電池 |
EP3719893A4 (en) * | 2017-11-30 | 2021-06-30 | Zeon Corporation | COMPOSITION OF BINDER FOR NON-AQUEOUS SECONDARY BATTERY, COMPOSITION OF SLURRY FOR FUNCTIONAL LAYER OF NON-AQUEOUS SECONDARY BATTERY, FUNCTIONAL LAYER OF NON-AQUEOUS SECONDARY BATTERY, BATTERY ELEMENT FOR NON-AQUEOUS SECONDARY BATTERY, AND NON-AQUEOUS SECONDARY BATTERY |
US11482707B2 (en) | 2017-11-30 | 2022-10-25 | Zeon Corporation | Binder composition for non-aqueous secondary battery, slurry composition for non-aqueous secondary battery functional layer, functional layer for non-aqueous secondary battery, battery component for non-aqueous secondary battery, and non-aqueous secondary battery |
JP7338473B2 (ja) | 2017-11-30 | 2023-09-05 | 日本ゼオン株式会社 | 非水系二次電池用バインダー組成物、非水系二次電池機能層用スラリー組成物、非水系二次電池用機能層、非水系二次電池用電池部材および非水系二次電池 |
CN111902980A (zh) * | 2018-04-03 | 2020-11-06 | 日本瑞翁株式会社 | 非水系二次电池功能层用组合物、非水系二次电池构件以及非水系二次电池 |
CN111902980B (zh) * | 2018-04-03 | 2024-02-27 | 日本瑞翁株式会社 | 非水系二次电池功能层用组合物、非水系二次电池构件以及非水系二次电池 |
WO2020257425A1 (en) * | 2019-06-19 | 2020-12-24 | Arkema Inc. | Reticulated composite material |
CN113993700A (zh) * | 2019-06-19 | 2022-01-28 | 阿科玛股份有限公司 | 网状复合材料 |
WO2021200083A1 (ja) * | 2020-03-31 | 2021-10-07 | 日本ゼオン株式会社 | 電気化学素子機能層用組成物、電気化学素子用積層体、および電気化学素子 |
CN115039282A (zh) * | 2020-03-31 | 2022-09-09 | 日本瑞翁株式会社 | 电化学元件功能层用组合物、电化学元件用层叠体以及电化学元件 |
Also Published As
Publication number | Publication date |
---|---|
JPWO2011013604A1 (ja) | 2013-01-07 |
JP5598472B2 (ja) | 2014-10-01 |
KR20120051653A (ko) | 2012-05-22 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5598472B2 (ja) | 二次電池用多孔膜及び二次電池 | |
JP5765228B2 (ja) | 二次電池用多孔膜及び二次電池 | |
JP5696664B2 (ja) | 二次電池用電極、二次電池電極用バインダー及び二次電池 | |
JP5561276B2 (ja) | 多孔膜及び二次電池 | |
JP5742717B2 (ja) | 二次電池用多孔膜及び二次電池 | |
JP5621772B2 (ja) | 二次電池用電極及び二次電池 | |
JP5617725B2 (ja) | 二次電池用電極、二次電池電極用バインダー、製造方法及び二次電池 | |
KR101921659B1 (ko) | 이차 전지 다공막 슬러리, 이차 전지 다공막, 이차 전지 전극, 이차 전지 세퍼레이터, 이차 전지, 및 이차 전지 다공막의 제조 방법 | |
KR101980368B1 (ko) | 이차 전지 다공막 슬러리, 이차 전지 다공막, 이차 전지 전극, 이차 전지 세퍼레이터 및 이차 전지 | |
JP5601472B2 (ja) | 多孔膜、二次電池電極及びリチウムイオン二次電池 | |
JP5867731B2 (ja) | 二次電池多孔膜スラリー、二次電池多孔膜、二次電池電極、二次電池セパレーター、二次電池及び二次電池多孔膜の製造方法 | |
KR101903376B1 (ko) | 이차 전지 다공막 슬러리, 이차 전지 다공막, 이차 전지 전극, 이차 전지 세퍼레이터 및 이차 전지 | |
KR101819067B1 (ko) | 이차 전지용 정극 및 그 제조 방법, 슬러리 조성물, 그리고 이차 전지 | |
KR20140004156A (ko) | 이차 전지용 다공막, 이차 전지 다공막용 슬러리 및 이차 전지 | |
WO2010016476A1 (ja) | リチウムイオン二次電池用電極 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 10804350 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2011524761 Country of ref document: JP Kind code of ref document: A |
|
ENP | Entry into the national phase |
Ref document number: 20127002047 Country of ref document: KR Kind code of ref document: A |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 10804350 Country of ref document: EP Kind code of ref document: A1 |