WO2011001848A1 - 二次電池用電極及び二次電池 - Google Patents
二次電池用電極及び二次電池 Download PDFInfo
- Publication number
- WO2011001848A1 WO2011001848A1 PCT/JP2010/060565 JP2010060565W WO2011001848A1 WO 2011001848 A1 WO2011001848 A1 WO 2011001848A1 JP 2010060565 W JP2010060565 W JP 2010060565W WO 2011001848 A1 WO2011001848 A1 WO 2011001848A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- segment
- electrode
- secondary battery
- graft polymer
- polymer
- 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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/621—Binders
-
- 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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
- H01M4/139—Processes of manufacture
-
- 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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
-
- 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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/621—Binders
- H01M4/622—Binders being polymers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Definitions
- the present invention relates to an electrode for a secondary battery and a binder that is a component thereof, and more particularly to an electrode that can be used for a lithium ion secondary battery and the like and that can provide a battery having high output characteristics and cycle characteristics.
- the present invention also relates to a secondary battery having such an electrode.
- Lithium ion secondary batteries show the highest energy density among practical batteries, and are widely used especially for small electronics. It is also expected to be used for automobile applications. Among them, there is a demand for higher output of lithium ion secondary batteries and further improvement in reliability such as cycle characteristics.
- Lithium ion secondary batteries are generally used as a positive electrode active material by bonding lithium-containing metal oxides such as LiCoO 2 , LiMn 2 O 4 and LiFePO 4 with a binder such as polyvinylidene fluoride. Is formed.
- the negative electrode is formed by bonding a carbonaceous (amorphous) carbon material, metal oxide or metal sulfide used as a negative electrode active material with a binder such as a styrene-butadiene copolymer. Is formed.
- Patent Document 1 discloses that a graft polymer is added as a dispersant in addition to a binder such as polyvinylidene fluoride in the positive electrode. ing.
- a graft polymer composed of vinylpyrrolidone and styrene as the dispersant, the dispersibility of the conductive agent is improved.
- non-uniformity of the conductive agent in the electrode is suppressed, and a battery having excellent cycle characteristics is obtained. It has been.
- Patent Document 2 discloses that a graft polymer composed of an olefin and acrylonitrile is used in the positive electrode, and maintains the binding property with the active material by suppressing the swelling property to the electrolytic solution, A battery having excellent cycle characteristics is obtained.
- an object of the present invention is to provide an electrode for a lithium ion secondary battery in which the obtained secondary battery has high output characteristics and gas generation is suppressed.
- the present inventors include, as a binder, a graft polymer composed of a component having a low swellability to an electrolytic solution and a high component as a binder.
- a graft polymer composed of a component having a low swellability to an electrolytic solution and a high component as a binder.
- a graft polymer contains a component with low swellability to electrolyte solution, and a high component
- a low swelling component adsorb
- the present invention for solving the above-mentioned problems includes the following matters as a gist.
- An electrode for a secondary battery comprising a segment A and a segment polymer having a swelling degree of 500 to 50,000% with respect to the electrolytic solution or a segment B dissolved in the electrolytic solution.
- the segment B is a segment of a soft polymer having a glass transition temperature of 15 ° C. or lower.
- a graft polymer comprising a segment A having a degree of swelling with respect to the electrolytic solution of 100 to 300% and a segment B having a degree of swelling with respect to the electrolytic solution of 500 to 50,000% or dissolved in the electrolytic solution.
- a binder for secondary batteries is a binder for secondary batteries.
- Graft polymer, active material comprising segment A having a degree of swelling of 100 to 300% with respect to the electrolyte and segment B having a degree of swelling with respect to the electrolyte of 500 to 50,000% or dissolved in the electrolyte
- the slurry containing the solvent is applied onto a current collector and dried, the method for producing an electrode for a secondary battery according to (1) above.
- a lithium ion secondary battery having a positive electrode, an electrolytic solution, and a negative electrode, wherein at least one of the positive electrode and the negative electrode is the secondary battery electrode according to any one of (1) to (4).
- the graft polymer suppresses gas generation on the surface of the electrode active material, and further has a high conductive agent dispersibility.
- the electrode for secondary batteries which can show a high output characteristic can be obtained.
- the electrode for a secondary battery of the present invention (hereinafter sometimes simply referred to as “electrode”) is formed by laminating an electrode active material layer containing an active material and a binder on a current collector. That is, the electrode of the present invention includes a current collector and an electrode active material layer that is laminated on the current collector and contains an active material and a binder.
- the electrode of the present invention comprises, as the binder, a segment A having a degree of swelling of 100 to 300% with respect to the electrolytic solution, and a segment having a degree of swelling of 500 to 50,000% with respect to the electrolytic solution or dissolved in the electrolytic solution.
- a graft polymer consisting of B. Electrode active material
- the electrode active material used for the secondary battery electrode of the present invention is generally selected according to the secondary battery in which the electrode is used. Examples of 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 such as polyacetylene or poly-p-phenylene can be used.
- An iron-based 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 load 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-based carbon fibers, and conductive polymers 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 diameter of the negative electrode active material is appropriately selected in consideration of other constituent elements of the battery. From the viewpoint of improving battery characteristics such as initial efficiency, load 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.
- Particles made of a hydrogen storage alloy are preferred.
- 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 preferable because the pulverization associated with is suppressed and the charge / discharge cycle characteristics are improved.
- the content ratio of the electrode active material used in the present invention in the electrode active material layer is preferably 90 to 99.9% by mass, more preferably 95 to 99% by mass.
- the electrode for a secondary battery according to the present invention includes, as a binder, a segment A having a degree of swelling of 100 to 300% with respect to the electrolyte and a degree of swelling of 500 to 50,000% with respect to the electrolyte or A graft polymer consisting of segment B which dissolves.
- the graft polymer used in the present invention has two segments (segment A and segment B), one of which constitutes the main chain, and the other has a branched structure constituting the graft portion (side chain).
- the graft polymer may further comprise one or more optional segments.
- each of the first segment and the second segment may be a segment based on only one type of polymerization unit, or may be a segment based on two or more types of polymerization units.
- the two segments have a swelling degree of 100 to 300% with respect to the electrolyte so that the retention of the electrolyte can be improved to improve the output characteristics, and further, the adsorption to the active material can be enhanced to suppress gas generation.
- segment B having a swelling degree of 500 to 50,000% with respect to the electrolytic solution or dissolved in the electrolytic solution.
- the graft polymer includes a segment A having a degree of swelling of 100 to 300% with respect to the electrolytic solution and a segment B having a degree of swelling of 500 to 50,000% with respect to the electrolytic solution or dissolved in the electrolytic solution, It was found that the segment A, which is a low swelling component, adsorbs to the active material and the conductive agent in the slurry, and the segment B, which is a high swelling component, spreads in the solvent, thereby exhibiting high slurry stability and dispersibility.
- the graft polymer used in the present invention may constitute the graft portion (side chain), regardless of which of the two segments constitutes the main chain.
- the graft polymer used in the present invention since the highly swollen segment B spreads in the slurry solvent in the slurry, and the low swollen segment A adsorbs to the active material and the conductive agent, it exhibits high conductive agent dispersibility and active material protection effect.
- a structure composed of segment A having a low swelling side chain is preferable. Therefore, a graft polymer in which segment A constitutes a graft portion (side chain) and segment B constitutes a main chain is preferable.
- 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. . Thereafter, it is immersed in an electrolytic solution at a temperature of 60 ° C. for 72 hours. The soaked film is pulled up, the weight immediately after wiping off the electrolytic solution (weight after soaking) is measured, and the value of (weight after soaking) / (weight before soaking) ⁇ 100 (%) is defined as the degree of swelling.
- a solution prepared by dissolving LiPF 6 at a concentration of 1 mol / liter in a mixed solvent is used.
- the degree of swelling of segment A and segment B with respect to the electrolyte can be controlled by the composition, molecular weight, and degree of crosslinking.
- the degree of swelling of the segment A with respect to the electrolytic solution is 100% to 300%, the adsorptivity to the active material and the conductive agent is increased, and the effect of suppressing gas generation is increased. preferable.
- the degree of swelling of the segment B with respect to the electrolytic solution is 500% to 50,000% or dissolved, and high binding property can be maintained while maintaining the electrolytic solution retention. , 000%, more preferably 500% to 5,000%.
- the weight average molecular weight of the segment A shall be 4,000 or more and 10,000 or less. By making the weight average molecular weight fall within this range, the dispersibility in the conductive agent and the active material and the slurry stability can be improved.
- the weight average molecular weight refers to a polystyrene-converted weight average molecular weight measured by gel permeation chromatography (GPC).
- 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 solubility parameter of the monomer can be determined according to the “molecular attraction 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.
- G molecular attraction constant
- the monomer component having a hydrophobic portion examples include styrene such as styrene, ⁇ -styrene, chlorostyrene, vinyl toluene, t-butylstyrene vinyl methyl benzoate, vinyl naphthalene, chloromethyl styrene, ⁇ -methyl styrene, and divinylbenzene.
- System monomers the segment A having a degree of swelling of 100 to 300% is preferably an ⁇ , ⁇ -unsaturated nitrile compound or a styrene monomer because it does not show any swellability to an electrolytic solution.
- a styrene monomer is most preferable because of high dispersibility of the conductive agent.
- the content of the monomer component having a hydrophobic part in segment A is preferably 10% by mass or more and 100% by mass or less, more preferably 20% by mass or more and 100% by mass with respect to 100% by mass of the total amount of monomers. It is as follows.
- the content of the monomer component having a hydrophobic portion in the segment A can be controlled by the monomer charge ratio at the time of producing the graft polymer. By making content of the monomer component which has the hydrophobic part in the segment A into the said range, higher electrolyte solution resistance and a high temperature characteristic are shown.
- these monomers may be used alone or in combination of two or more.
- the weight average molecular weight of the segment B shall be 10,000 or more and 500,000 or less. By making the weight average molecular weight fall within this range, it has high binding properties and does not cause peeling of the electrode active material layer.
- Monomers having a solubility parameter of 8.0 to less than 11 include alkenes such as ethylene and propylene; methacrylic acid alkyl esters such as butyl methacrylate, hexyl methacrylate, lauryl methacrylate, stearyl methacrylate; butyl acrylate, hexyl acrylate Alkyl acrylates such as lauryl acrylate and stearyl acrylate; diene monomers such as butadiene and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate and vinyl benzoate.
- acrylic acid alkyl ester or methacrylic acid alkyl ester is more preferable because of its high swellability to electrolyte solution and high stability to redox.
- alkyl acrylate or alkyl methacrylate examples include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, acrylic Acrylic acid alkyl esters such as 2-methoxyethyl acid, 2-ethoxyethyl acrylate, and benzyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, methacryl Methacrylic acid alkyl esters such as t-butyl acid, 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, and benzyl methacrylate; It is.
- the content of the monomer component having a solubility parameter (SP) in Component B of 8.0 or more and less than 11 is preferably 30% by mass or more, more preferably 50 to 90% with respect to 100% by mass of the total amount of monomers. It is the range of mass%.
- the content of the monomer component having a solubility parameter (SP) in the second segment of 8.0 or more and less than 11 can be controlled by the monomer charge ratio at the time of producing the graft polymer.
- the content of the monomer component having a solubility parameter (SP) of 8.0 or more and less than 11 is in an appropriate range, so that it does not dissolve but exhibits elution inside the battery while exhibiting swelling property to the electrolyte. It does not occur and exhibits high temperature characteristics.
- the monomer component having a hydrophilic group includes a monomer having a —COOH group (carboxylic acid group), a monomer having a —OH group (hydroxyl group), and a monomer having a —SO 3 H group (sulfonic acid group).
- 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, R1 is hydrogen or methyl An ester of a polyalkylene glycol represented by a group and (meth) acrylic acid; Mono (meth) acrylic acid esters of dihydroxy esters of dicarboxylic acids such as ethyl
- Examples of monomers 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-acrylamido-2-methyl. Examples thereof include propanesulfonic acid and 3-allyloxy-2-hydroxypropanesulfonic acid.
- 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 B is composed of a monomer component having the hydrophilic group, among these monomers having a hydrophilic group, from the viewpoint of further improving the dispersibility of the active material, A monomer having an acid group is preferred.
- the content of the monomer component having a hydrophilic group in the segment B is preferably 0.5 to 40% by mass with respect to 100% by mass of the total amount of monomers as a monomer having a hydrophilic group at the time of polymerization. %, More preferably 3 to 20% by mass.
- the content of the monomer having a hydrophilic group in the segment B can be controlled by the monomer charging ratio at the time of producing the graft polymer. When the content of the monomer having a hydrophilic group in the segment B is within a predetermined range, swelling to an appropriate electrolytic solution is exhibited, and elution or the like inside the battery does not occur.
- these monomers may be used alone or in combination of two or more.
- a copolymer of an acrylic acid alkyl ester or a methacrylic acid alkyl ester and a monomer having a carboxylic acid group is preferable because it has a high swellability to an electrolytic solution and is highly stable in redox.
- the glass transition temperature of segment A, segment B, or both of these is 15 ° C. or lower because an electrode having high flexibility can be obtained.
- the segment A is adsorbed on the active material surface inside the electrode, and the segment B is present on the outside (the surface of the binder layer attached to the surface of the active material particles on the side far from the active material). Therefore, the glass transition temperature of segment B is preferably 15 ° C. or lower, more preferably ⁇ 5 ° C. or lower, particularly preferably ⁇ 40 ° C. or lower.
- the mobility of the segment B site is increased in a state where the segment A site in the graft polymer is adsorbed on the active material surface, so that the Li ion acceptability at a low temperature is improved.
- the lower limit of the glass transition temperature of segment A, segment B, or both is not particularly limited, but is ⁇ 100 ° C. This can be done.
- the glass transition temperature of a segment can be adjusted by combining further the combination of the monomer of an illustration, and the copolymerizable monomer mentioned later.
- the ratio of segment A to segment B in the graft polymer varies depending on the composition, the degree of crosslinking, etc. in order to have high rate characteristics while controlling the degree of swelling in the electrolyte within a predetermined range.
- the ratio of segment A: segment B is 20:80 to 80:20, more preferably 30:70 to 70:30 by mass ratio. .
- the degree of swelling of segment A and segment B in the graft polymer with respect to the electrolyte can be adjusted by controlling the molecular weight and the degree of crosslinking in addition to the ratio of segment A and segment B described above.
- the degree of swelling with respect to the electrolytic solution increases as the molecular weight decreases, and tends to decrease as the molecular weight increases. Therefore, the range of the weight average molecular weight of the graft polymer for obtaining a suitable degree of swelling varies depending on the structure and the degree of crosslinking, but is measured by, for example, gel permeation chromatography using tetrahydrofuran (THF) as a developing solvent.
- THF tetrahydrofuran
- the standard polystyrene equivalent value is 1,000 to 500,000, more preferably 2,000 to 100,000.
- the degree of swelling of the segment A and segment B in the graft polymer with respect to the electrolyte solution is controlled by the degree of crosslinking of the graft polymer
- the preferred range of degree of crosslinking varies depending on the structure, molecular weight, etc. It is preferable that the degree of crosslinking is such that it dissolves or swells to 400% or more when immersed in a solvent for 24 hours.
- the degree of crosslinking method of the graft polymer include a method of crosslinking by heating or energy ray irradiation.
- the degree of crosslinking can be adjusted by heating conditions or irradiation conditions (intensity, etc.) of irradiation with energy rays. Further, since 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. Examples of the method for obtaining a graft polymer that can be crosslinked by heating or energy ray irradiation include a method of introducing a crosslinkable group into the graft polymer and a method of using a crosslinking agent in combination.
- Examples of the method of introducing a crosslinkable group into the graft polymer include a method of introducing a photocrosslinkable crosslinkable group into the graft polymer and a method of introducing a heat crosslinkable crosslinkable group.
- the method of introducing a heat-crosslinkable crosslinkable group into the graft polymer can crosslink the binder by applying heat treatment to the electrode plate after applying the electrode plate, and further dissolve in the electrolyte. This is preferable because a tough and flexible electrode plate can be obtained.
- the heat-crosslinkable crosslinkable group is selected from the group consisting of an epoxy group, an N-methylolamide group, an oxetanyl group, and an oxazoline group.
- an epoxy group is more preferable 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 graft polymer is preferably 0.1% with respect to 100% by mass 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 mass, more preferably 0.1 to 5% by mass.
- the content ratio of the heat-crosslinkable crosslinkable group in the graft polymer can be controlled by the monomer charge ratio when the graft polymer is produced.
- the segment A and the segment B exhibit a predetermined swelling property, and can exhibit high rate characteristics and a gas generation suppressing effect.
- 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 degree of swelling of the graft polymer with respect to the electrolytic solution is preferably in the range of 100% to 300%, and more preferably in the range of 100% to 200%. Since the degree of swelling of the graft polymer with respect to the electrolyte solution is in the above range, the rate of swelling of the electrolyte material without losing the active material is exhibited while exhibiting the binding property in the positive electrode layer at the time of battery production. Characteristic can be expressed.
- the degree of swelling of the graft polymer with respect to the electrolytic solution can be adjusted by controlling the composition, molecular weight, and degree of crosslinking in the same manner as the degree of swelling of the segment A and segment B with respect to the electrolytic solution.
- the graft polymer used in the present invention may contain a monomer copolymerizable with these in addition to the monomer components described above.
- 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 vinyl acetate, vinyl propionate, vinyl butyrate, etc .; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether; methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone , Vinyl ketones such as hexyl vinyl ketone and isopropenyl vinyl ketone; heterocycle-containing vinyl compounds such as N-vinyl pyrrolidone, vinyl pyridine and vinyl imidazole; acrylamide, N-methyl
- the glass transition temperature of the graft polymer can impart flexibility to the electrode plate at room temperature, and suppress cracks during winding and winding of the electrode plate, chipping of the electrode plate layer, and the like. From the viewpoint of being able to reduce the temperature, it is preferably 20 ° C or lower, more preferably 0 ° C or lower.
- the lower limit of the glass transition temperature of the graft polymer is not particularly limited, but can be ⁇ 100 ° C. or higher.
- the glass transition temperature of the graft polymer can be adjusted by changing the use ratio of the constituent monomers.
- the graft polymer used in the present invention is synthesized by 1) a method of copolymerizing to form a branched structure, or 2) a method of modifying the obtained polymer to generate a branched structure.
- the method 1) is preferable because the desired structure can be obtained in one step.
- a method of copolymerizing so as to constitute 1) the branched structure for example, a graft polymer can be obtained by a chain transfer reaction by polymerizing a graft monomer in the presence of a trunk polymer by a known polymerization method.
- a graft polymer can be obtained by introducing a functional group capable of generating radicals or ions into the trunk polymer and initiating a polymerization reaction of the graft monomer from the functional group.
- a branch polymer obtained by polymerizing a graft monomer capable of forming a branched structure at the time of polymerization by a known polymerization method may be added to the trunk polymer by a radical addition reaction or the like.
- the graft polymer can be produced by a method described in JP-B-6-51767.
- the structure control is most easily controlled by a method in which a branched polymer obtained by polymerizing a graft monomer capable of forming a branched structure at the time of polymerization by a known polymerization method is added to a trunk polymer by a radical addition reaction or the like. Since the slurry for secondary battery electrodes described later is easy to stabilize, it is preferable. Specifically, a method of copolymerizing using a macromonomer as a branch polymer can be mentioned.
- One-terminal methacryloylated polystyrene-acrylonitrile oligomer (“AN-6S” manufactured by Toa Gosei Kagaku Kogyo Co., Ltd.) and the like.
- a polymer having a functional group such as a hydroxyl group at one end such as polyoxyethylene monomethyl ether, isocyanatoethyl methacrylate, acrylic acid or methacrylic acid (hereinafter sometimes abbreviated as “(meth) acrylic acid”)
- Various macromonomers can also be obtained by reacting an ethylenically unsaturated monomer having a functional group such as (meth) acrylic acid chloride and glycidyl (meth) acrylate.
- a graft polymer can be obtained by copolymerizing these macromonomers and other ethylenically unsaturated monomers.
- the polymerization method of the graft polymer is not particularly limited, and any method such as a solution polymerization method, a suspension polymerization method, a bulk polymerization method, and an emulsion polymerization method can be used.
- the polymerization method any method such as ionic polymerization, radical polymerization, and living radical polymerization can be used.
- the polymerization initiator used for the polymerization include lauroyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-butyl peroxypivalate, 3,3,5-trimethylhexanoyl peroxide, and the like.
- Organic peroxides, azo compounds such as ⁇ , ⁇ ′-azobisisobutyronitrile, ammonium persulfate, potassium persulfate, and the like.
- the graft 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 graft polymer production step.
- the content of the particulate metal component contained in the graft polymer composition is 0 ppm or more and 10 ppm or less, the metal ion cross-linking between polymers in the secondary battery electrode slurry described later is prevented, and the viscosity is increased. Can be prevented. Furthermore, there is little concern about self-discharge increase due to internal short circuit of the secondary battery or dissolution / precipitation during charging, and the cycle characteristics and safety of the battery are improved.
- 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, but in consideration of productivity and removal efficiency, it is preferably performed by placing a magnetic filter in the graft polymer production line. .
- the content ratio of the graft polymer in the binder is preferably 30% by mass or more and 100% by mass or less, more preferably 45% by mass or more and 100% by mass or less, and most preferably 60% by mass, assuming that the total amount of the binder is 100% by mass. It is not less than 100% by mass.
- the content ratio of the graft polymer in the binder is within the above range, the lithium migration is inhibited while maintaining the binding property between the active material particles and the binding property to the electrode or the separator. An increase in resistance can be suppressed.
- the binder may further contain other binder components (that is, the binder of the present invention can act as a binder other than the graft polymer).
- the electrode for a secondary battery of the present invention may contain a component that can act as a binder other than the graft polymer. .)
- binder components various resin components can be used in combination.
- polyethylene polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyacrylic acid, polyacrylonitrile, polyacrylate, polymethacrylate, or the like may be used. it can.
- a copolymer containing 50% or more of the resin component that is, in the unit of the copolymer and constituting the copolymer, the same unit as the unit constituting the resin is 50% or more and 100% or less
- polyacrylic acid derivatives such as acrylic acid-styrene copolymers and acrylic acid-acrylate copolymers, acrylonitrile-styrene copolymers, acrylonitrile-acrylate copolymers, etc.
- the polyacrylonitrile derivative can also be used.
- 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 Or a homopolymer of a methacrylic acid derivative or a copolymer of monomers copolymerizable therewith; an acrylic soft polymer; an isobutylene soft such as polyisobutylene, isobutylene / isoprene rubber, isobutylene / styrene copolymer Polymer: Polybutadiene, polyisoprene, butadiene / styrene random copolymer, isoprene / styrene random copolymer, acrylonitrile
- These soft polymers may have a cross-linked structure or may have a functional group introduced by modification. These may be used alone or in combination of two or more. Among these, a polyacrylonitrile derivative is preferable for improving the dispersibility of the active material.
- the content of other binders is preferably 5% by mass to 80% by mass, more preferably 10% by mass to 70% by mass, and most preferably 20% by mass or more, with the total binder amount being 100% by mass. 60% by mass or less.
- the binder is within the above range, the internal resistance of the battery is not increased and high life characteristics can be exhibited.
- the content of the total binder in the secondary battery electrode is 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the active material. Since the content of the binder in the secondary battery electrode is in the above range, the binding between the active materials and the current collector is excellent and the flexibility is maintained, but the movement of Li is not hindered. Resistance does not increase.
- the electrode for a secondary battery of the present invention is formed by laminating an electrode active material layer containing an active material and a binder on a current collector.
- 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.
- the current collector is preferably used after roughening in advance.
- the roughening method include a mechanical polishing method, an electrolytic polishing method, and a chemical polishing method.
- the 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.
- the electrode for a secondary battery of the present invention may further contain an arbitrary component.
- the optional component include a conductivity-imparting material, a reinforcing material, a dispersant, a leveling agent, an antioxidant, a thickener, and an electrolytic solution additive having functions such as suppression of electrolytic solution decomposition. These are not particularly limited as long as they do not affect the battery reaction.
- 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 conductivity imparting material By using the conductivity imparting material, the electrical contact between the electrode active materials can be improved. In particular, when used in a lithium ion secondary battery, the discharge load characteristics can be improved.
- the reinforcing material various inorganic and organic spherical, plate-like, rod-like or fibrous fillers can be used. By using a reinforcing material, a tough and flexible electrode can be obtained, and excellent long-term cycle characteristics can be exhibited.
- the amount of the conductivity-imparting material and the reinforcing agent used is usually 0.01 to 20 parts by mass, preferably 1 to 10 parts by mass with respect to 100 parts by mass of the electrode active material. By being included in the said range, a high capacity
- the dispersant examples include anionic compounds, cationic compounds, nonionic compounds, and polymer compounds.
- a dispersing agent is selected according to the electrode active material and electrically conductive agent to be used.
- the content ratio of the dispersant in the electrode is preferably 0.01 to 10 parts by mass.
- the 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.
- the content of the leveling agent in the electrode is preferably 0.01 to 10 parts by mass. When the leveling agent is within the above range, the productivity, smoothness, and battery characteristics during electrode production are excellent.
- the antioxidant 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.
- the content of the antioxidant in the electrode is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass. When the antioxidant is in the above range, the slurry stability, battery capacity and cycle characteristics are excellent.
- 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, copolymers of acrylic acid or acrylate and vinyl alcohol, maleic anhydride or copolymers of maleic acid or fumaric acid and vinyl alcohol; polyethylene glycol, polyethylene oxide, polyvinyl pyrrolidone, modified Polyacrylic 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; (modified) poly (meth) acrylic acid and ammonium salts and alkali metal salts thereof
- (modified) poly means “unmodified poly” or “modified poly”
- (meth) acryl means “acryl” or “methacryl”.
- the content of the thickener in the electrode is preferably 0.01 to 10 parts by mass.
- the electrolytic solution additive vinylene carbonate used in an electrode slurry and an electrolytic solution described later can be used.
- the content ratio of the electrolytic solution additive in the electrode is preferably 0.01 to 10 parts by mass.
- the electrolytic solution additive is in the above range, the cycle characteristics and the high temperature characteristics are excellent.
- Other examples include nano-particles such as fumed silica and fumed alumina: surfactants such as alkyl surfactants, silicon surfactants, fluorine surfactants, and metal surfactants.
- the slurry stability and productivity are excellent, and high battery characteristics are exhibited.
- the dispersibility of the active material and the like in the electrode forming slurry can be improved, and the smoothness of the electrode obtained thereby can be improved.
- the content ratio of the surfactant in the electrode is preferably 0.01 to 10 parts by mass.
- the method for producing an electrode for a secondary battery of the present invention may be any method as long as the electrode is bonded in layers on at least one side, preferably both sides of the current collector.
- a secondary battery electrode slurry described later is applied to a current collector, dried, and then heat-treated at 120 ° C. or higher for 1 hour or longer to form an electrode.
- the upper limit of the temperature of heat processing is not specifically limited, It can be 200 degrees C or less.
- the upper limit of the heat treatment time is not particularly limited, but can be 24 hours or less.
- the secondary battery electrode slurry used in the present invention includes a binder containing a graft polymer, an active material, and a solvent.
- a binder containing a graft polymer examples include the same materials as those described for the secondary battery electrode.
- the solvent is not particularly limited as long as it can uniformly dissolve or disperse the binder of the present invention.
- the solvent used for the secondary battery electrode slurry 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; acetone, ethyl methyl ketone, disopropyl ketone, cyclohexanone, methylcyclohexane, and ethylcyclohexane.
- Ketones Chlorinated aliphatic hydrocarbons such as methylene chloride, chloroform, and carbon tetrachloride; Esters such as ethyl acetate, butyl acetate, ⁇ -butyrolactone, and ⁇ -caprolactone; Acylonitriles such as acetonitrile and propionitrile; Tetrahydrofuran , Ethers such as ethylene 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 solubility of the polymer of the present invention, excellent dispersibility of the electrode active material and the conductive agent, and having a low boiling point and high volatility is preferable because it can be removed at a low temperature in a short time.
- 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 secondary battery electrode used in the present invention is not particularly limited as long as the slurry can be applied and immersed, and has a fluid viscosity, but is generally 10 to 80. It is about mass%.
- Components other than the solid content are components that volatilize in the drying process, and include, in addition to the solvent, for example, a medium in which these are dissolved or dispersed during the preparation and addition of the graft polymer. Since the secondary battery electrode slurry of the present invention is for forming the secondary battery electrode of the present invention, the inclusion of the electrode active material and the graft polymer in the total solid content of the secondary battery electrode slurry. The ratio is, of course, as described above for the electrode active material layer of the secondary battery electrode of the present invention.
- the secondary battery electrode slurry further includes a dispersant used in the above-mentioned secondary battery electrode and an electrolytic solution decomposition inhibitor.
- a dispersant used in the above-mentioned secondary battery electrode and an electrolytic solution decomposition inhibitor.
- Arbitrary components such as electrolyte solution additive which has a function, may be contained. These are not particularly limited as long as they do not affect the battery reaction.
- the method for producing the slurry for the secondary battery electrode is not particularly limited, and can be obtained by mixing the binder, the active material, and the solvent including the graft polymer with other components added as necessary. .
- an electrode slurry in which the electrode active material and the conductive agent are highly dispersed can be obtained regardless of the mixing method and the mixing order.
- the mixing device is not particularly limited as long as it can uniformly mix the above-mentioned components. Bead mill, ball mill, roll mill, sand mill, pigment disperser, crusher, ultrasonic disperser, homogenizer, planetary mixer, fill mix, etc.
- the viscosity of the secondary battery electrode slurry is preferably 10 mPa ⁇ s to 100,000 mPa ⁇ s, more preferably 100 to 50,000 mPa ⁇ s, from the viewpoints of uniform coating properties 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 method for applying the slurry for the secondary battery electrode to the current collector is not particularly limited. Examples thereof include a doctor blade method, a zip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, and a brush coating method. Examples of 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 it is preferable to lower the porosity of the electrode by pressure treatment using a mold press or a roll press.
- a preferable range of the porosity is 5% to 15%, more preferably 7% to 13%. If the porosity is too high, charging efficiency and discharging efficiency are deteriorated. When the porosity is too low, there are problems that it is difficult to obtain a high volume capacity, or that the electrodes are easily peeled off and are likely to be defective. Further, when a curable polymer is used, it is preferably cured.
- the thickness of the electrode for a secondary battery of the present invention is usually 5 to 300 ⁇ m, preferably 10 to 250 ⁇ m. When the electrode thickness is in the above range, both load characteristics and energy density are high.
- the secondary battery of the present invention includes a positive electrode, a negative electrode, a separator, and an electrolytic solution, and at least one of the positive electrode and the negative electrode is the secondary battery electrode.
- the conductive agent and the active material are often used in combination, the rate characteristics are often lowered due to poor dispersibility of the conductive agent, and the reaction of the electrolyte solution on the active material surface due to the high potential is also observed. A large effect can be obtained when it is used for the positive electrode because it is likely to occur and a large amount of gas is generated.
- Examples of the secondary battery include a lithium ion secondary battery and a nickel hydride secondary battery.
- lithium ion secondary battery is used as the most demanded performance improvement such as suppression of gas generation and improvement of output characteristics.
- a battery is preferred.
- the case where it uses for a lithium ion secondary battery is demonstrated.
- Electrode for lithium ion secondary battery 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 above-described slurry for secondary battery electrodes.
- VC vinylene carbonate
- the concentration of the supporting electrolyte in the electrolytic solution for the lithium ion secondary battery is usually 1 to 30% by mass, preferably 5 to 20% by mass.
- 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.
- the electrolytic solution other than the above 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.
- separator for lithium ion secondary battery
- known ones such as a microporous film or non-woven fabric made of polyolefin such as polyethylene and polypropylene; a porous resin coat containing inorganic ceramic powder; and the like can be used.
- a separator for a lithium ion secondary battery known ones such as a microporous film or non-woven fabric containing a polyolefin resin such as polyethylene or polypropylene or an aromatic polyamide resin; a porous resin coat containing an inorganic ceramic powder can be used. .
- a polyolefin film polyethylene, polypropylene, polybutene, polyvinyl chloride
- a microporous film made of a resin such as a mixture or copolymer thereof, polyethylene terephthalate, polycycloolefin, polyether sulfone, polyamide, polyimide, polyimide amide
- a microporous membrane made of a resin such as polyaramid, polycycloolefin, nylon, and polytetrafluoroethylene, or a woven fabric of polyolefin fibers, a nonwoven fabric thereof, an aggregate of insulating substance particles, or the like.
- a microporous film made of a polyolefin-based resin is preferable because the thickness of the entire separator can be reduced and the active material ratio in the battery can be increased to increase the capacity per volume.
- the thickness of the separator 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 during battery production is excellent.
- 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. 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.
- a solution prepared by dissolving LiPF 6 at a concentration of 1 mol / liter in the mixed solvent is used. The smaller the swelling degree, the higher the electrolyte resistance of the polymer.
- ⁇ Slurry characteristics Dispersibility> A slurry is put into a test tube having a diameter of 1 cm to a height (depth) of 5 cm to obtain a test sample. Five test samples are prepared per measurement of one sample. The test sample is placed vertically on a desk. The state of the installed slurry is observed for 10 days and judged according to the following criteria. Of the five samples, the day when sedimentation was earliest was taken as the day when sedimentation was observed. It shows that the dispersibility is so excellent that no sedimentation is observed. A: No settling is observed even after 10 days. B: Settling is observed after 6 to 10 days. C: Sedimentation is observed after 2 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.
- ⁇ Battery characteristics Output characteristics> About a half cell coin type lithium ion secondary battery, it charges to 4.3V by a 0.1C constant current method, and discharges to 3.0V at 0.1C after that, and calculates
- the capacity retention represented by the ratio of the electric capacity of the 20C discharge capacity b and the 0.1C discharge capacity a ((b / a) ⁇ 100 (unit:%)) is obtained, and this is used as an evaluation criterion for rate characteristics. Judgment based on the criteria of. The higher this value, the better the output characteristics (rate characteristics).
- Example 1 ⁇ Production of graft polymer> In an autoclave equipped with a stirrer, 230 parts of toluene, 40 parts of styrene macromonomer (single-end methacryloylated polystyrene oligomer, “AS-6”, manufactured by Toagosei Co., Ltd.) as segment A, and monomer constituting segment B 60 parts of butyl acrylate and 1 part of t-butylperoxy-2-ethylhexanate as a polymerization initiator were added, stirred well, heated to 90 ° C., and polymerized (hereinafter referred to as “graft polymer”). 1 ”) was obtained.
- graft polymer 60 parts of butyl acrylate and 1 part of t-butylperoxy-2-ethylhexanate
- the polymerization conversion rate determined from the solid content concentration was approximately 98%.
- the weight average molecular weight of the graft polymer 1 was about 50,000.
- the weight average molecular weight was measured by gel permeation chromatography (GPC), and the weight average molecular weight in terms of standard polystyrene was determined.
- GPC was performed using HLC-8220 (manufactured by Tosoh Corporation).
- HLC-8220 manufactured by Tosoh Corporation
- the main chain was composed of butyl acrylate (a component exhibiting swelling property with respect to the electrolytic solution) and the side chain was composed of styrene (a component not exhibiting swelling property with respect to the electrolytic solution).
- the obtained toluene solution of graft polymer 1 was dried at 120 ° C. for 10 hours in a nitrogen atmosphere to prepare a polymer film, and the degree of swelling and the glass transition temperature were measured. The results are shown in Table 1.
- NMP N-methyl-2-pyrrolidone
- the positive electrode slurry 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
- a battery container was prepared using a laminate film in which both surfaces of an aluminum sheet were coated with a resin made of polypropylene. Next, the active material layer was removed from each end of the positive electrode and the negative electrode obtained above, and a tab was welded to the exposed foil. As the tab, a Ni tab was used for the positive electrode and a Cu tab was used for the negative electrode.
- the obtained positive and negative electrodes with tabs and a separator made of a polyethylene microporous membrane were stacked so that the active material layer surfaces of both electrodes faced each other and the separator was positioned therebetween. The obtained laminate was wound and stored in the battery container.
- LiPF 6 was dissolved to a concentration of 1 mol / liter in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 2 at 25 ° C. to prepare an electrolytic solution.
- This electrolyte was poured into the battery container.
- the laminate film was sealed, and the laminate cell which is the lithium ion secondary battery of this invention was produced.
- the gas generation amount of the obtained laminate cell was measured. The evaluation results are shown in Table 2.
- the positive electrode obtained above was cut into a circle having a diameter of 13 mm.
- a metal lithium metal foil was cut into a circle having a diameter of 14 mm as a negative electrode.
- 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.
- a circular positive electrode, metallic lithium metal foil, and a separator were placed 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.
- Example 2 In an autoclave equipped with a stirrer, 230 parts of toluene, 40 parts of styrene-acrylonitrile macromonomer (single terminal methacryloylated polystyrene-acrylonitrile oligomer, “AN-6S”, manufactured by Toagosei Co., Ltd.) as segment A, segment B 60 parts of butyl acrylate as a monomer and 1 part of t-butylperoxy-2-ethylhexanate as a polymerization initiator were added and stirred sufficiently. , “Graft Polymer 2”). The polymerization conversion rate determined from the solid content concentration was approximately 98%.
- the weight average molecular weight of the obtained graft polymer 2 was about 50,000.
- the main chain was composed of butyl acrylate (a component exhibiting swelling property with respect to the electrolytic solution), and the side chain was composed of acrylonitrile and styrene (a component not exhibiting swelling property with respect to the electrolytic solution).
- a polymer film of segment A and segment B was prepared in the same manner as in Example 1 except that a styrene-acrylonitrile macromonomer was used instead of the styrene macromonomer, and the degree of swelling and glass transition temperature were measured.
- the results are shown in Table 1.
- a polymer film, a slurry for a positive electrode, and a battery were prepared in the same manner as in Example 1 except that the graft polymer 2 was used instead of the graft polymer 1 as a binder constituting the positive electrode. Then, the swelling degree of the polymer film, the glass transition temperature, the sedimentation property in the positive electrode slurry, the rate characteristics of the battery, and the amount of gas generated were evaluated. The results are shown in Tables 1 and 2.
- Example 3 In an autoclave equipped with a stirrer, 230 parts of toluene, 57 parts of ethyl acrylate as a monomer constituting segment B, 3 parts of glycidyl methacrylate, and 1 part of t-butylperoxy-2-ethylhexanate as a polymerization initiator The mixture was sufficiently stirred and then polymerized by heating to 80 ° C. to obtain a polymer solution. Subsequently, after adding 40 parts of polyacrylonitrile having a terminal modified with a carboxyl group as a component constituting the segment A, the mixture is heated to 120 ° C.
- graft polymer 3 heat-modified polymer (hereinafter referred to as “graft polymer 3”). ) was obtained.
- the polymerization conversion rate determined from the solid content concentration was approximately 98%.
- the weight average molecular weight of the graft polymer 3 was about 70,000.
- the main chain was composed of ethyl acrylate (a component exhibiting swelling property with respect to the electrolytic solution), and the side chain was composed of acrylonitrile (a component not exhibiting swelling property with respect to the electrolytic solution).
- a polymer film, a slurry for positive electrode, and a battery were prepared in the same manner as in Example 1 except that graft polymer 3 was used instead of graft polymer 1 as a binder constituting the positive electrode. Then, the swelling degree of the polymer film, the glass transition temperature, the sedimentation property in the positive electrode slurry, the rate characteristics of the battery, and the amount of gas generated were evaluated. The results are shown in Tables 1 and 2.
- Example 4 In an autoclave equipped with a stirrer, 230 parts of toluene, 40 parts of styrene-acrylonitrile macromonomer (single terminal methacryloylated polystyrene-acrylonitrile oligomer, “AN-6S”, manufactured by Toagosei Co., Ltd.) as segment A, segment B After adding 60 parts of n-ethyl acrylate as a monomer, 1 part of t-butylperoxy-2-ethylhexanate as a polymerization initiator, and 0.05 part of n-dodecyl mercaptan as a molecular weight regulator, the mixture is sufficiently stirred.
- styrene-acrylonitrile macromonomer single terminal methacryloylated polystyrene-acrylonitrile oligomer, “AN-6S”, manufactured by Toagosei Co., Ltd.
- graft polymer 4 a polymer (hereinafter referred to as “graft polymer 4”) solution.
- the polymerization conversion rate determined from the solid content concentration was approximately 98%.
- the weight average molecular weight of the graft polymer 4 was about 30,000.
- the main chain was composed of n-ethyl acrylate (a component exhibiting swelling property with respect to the electrolytic solution), and the side chain was composed of styrene-acrylonitrile (a component not exhibiting swelling property with respect to the electrolytic solution).
- a polymer film of segment A was prepared in the same manner as in Example 1 except that a styrene-acrylonitrile macromonomer was used instead of the styrene macromonomer, and the degree of swelling and the glass transition temperature were measured. The results are shown in Table 1.
- a polymer film, a slurry for a positive electrode, and a battery were produced in the same manner as in Example 1 except that the graft polymer 4 was used instead of the graft polymer 1 as a binder constituting the positive electrode. Then, the swelling degree of the polymer film, the glass transition temperature, the sedimentation property in the positive electrode slurry, the rate characteristics of the battery, and the gas generation were evaluated. The results are shown in Tables 1 and 2.
- Example 5 ⁇ Production of graft polymer> In an autoclave equipped with a stirrer, 230 parts of toluene, 40 parts of styrene macromonomer (single-end methacryloylated polystyrene oligomer, “AS-6”, manufactured by Toagosei Co., Ltd.) as segment A, and monomer constituting segment B After adding 58 parts of butyl acrylate, 2 parts of glycidyl methacrylate and 1 part of t-butylperoxy-2-ethylhexanate as a polymerization initiator, the mixture was sufficiently stirred and heated to 90 ° C.
- styrene macromonomer single-end methacryloylated polystyrene oligomer, “AS-6”, manufactured by Toagosei Co., Ltd.
- the polymer to polymerize the polymer (hereinafter referred to as “polymer”). , “Graft Polymer 5”).
- the polymerization conversion rate determined from the solid content concentration was approximately 98%.
- the graft polymer 5 had a weight average molecular weight of about 50,000.
- the obtained graft polymer was composed of a copolymer of butyl acrylate and glycidyl methacrylate (a component showing swelling properties with respect to the electrolyte) and a side chain of styrene (a component not showing swelling properties with respect to the electrolyte). .
- the obtained toluene solution of the graft polymer 5 was dried at 120 ° C. for 10 hours in a nitrogen atmosphere to prepare a polymer film, and the degree of swelling was measured. The results are shown in Table 1.
- the positive electrode slurry 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.
- ⁇ Production of negative electrode slurry and negative electrode> As a negative electrode active material, 98 parts of graphite having a particle diameter of 20 ⁇ m and a specific surface area of 4.2 m 2 / g are mixed with 1.6 parts of a graft polymer 5 corresponding to a solid content as a binder, and N-methylpyrrolidone is further added. And mixed with a planetary mixer to prepare an electrode slurry for a negative electrode. This negative electrode slurry 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 active material layer having a thickness of 60 ⁇ m.
- a battery container was prepared using a laminate film in which both surfaces of an aluminum sheet were coated with a resin made of polypropylene. Next, the active material layer was removed from each end of the positive electrode and the negative electrode obtained above, and a tab was welded to the exposed foil. As the tab, a Ni tab was used for the positive electrode and a Cu tab was used for the negative electrode.
- the obtained positive and negative electrodes with tabs and a separator made of a polyethylene microporous membrane were stacked so that the active material layer surfaces of both electrodes faced each other and the separator was positioned therebetween. The obtained laminate was wound and stored in the battery container.
- LiPF 6 was dissolved to a concentration of 1 mol / liter in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 2 at 25 ° C. to prepare an electrolytic solution.
- This electrolyte was poured into the battery container.
- the laminate film was sealed, and the laminate cell which is the lithium ion secondary battery of this invention was produced.
- the laminated cell obtained was evaluated for lithium low temperature acceptance characteristics. The evaluation results are shown in Table 3.
- Example 6 In an autoclave equipped with a stirrer, 230 parts of toluene, 40 parts of styrene macromonomer (single-end methacryloylated polystyrene oligomer, “AS-6”, manufactured by Toagosei Co., Ltd.) as segment A, and monomer constituting segment B 50 parts of n-ethyl acrylate, 10 parts of acrylonitrile and 1 part of t-butylperoxy-2-ethylhexanate as a polymerization initiator were added and stirred sufficiently, and then heated to 90 ° C. to polymerize. (Hereinafter referred to as “graft polymer 6”).
- the polymerization conversion rate determined from the solid content concentration was approximately 98%.
- the graft polymer 6 had a weight average molecular weight of about 50,000.
- the main chain is composed of a copolymer of n-ethyl acrylate and acrylonitrile (a component exhibiting swelling property with respect to the electrolytic solution), and the side chain is composed of styrene (a component not exhibiting swelling property with respect to the electrolytic solution). It was.
- Polymer films of segment A and segment B were prepared in the same manner as in Example 1 except that vinylpyrrolidone was used instead of butyl acrylate and butyroacrylate macromonomer was used instead of styrene macromonomer. Was measured. The results are shown in Table 1.
- a polymer film, a slurry for positive electrode, and a battery were prepared in the same manner as in Example 1 except that graft polymer 7 was used instead of graft polymer 1 as a binder constituting the positive electrode. Then, the swelling degree of the polymer film, the glass transition temperature, the sedimentation property in the positive electrode slurry, the rate characteristics of the battery, and the gas generation were evaluated. The results are shown in Tables 1 and 2.
- a polymer film of segment A and segment B was prepared in the same manner as in Example 1 except that 500 parts of butyl acrylate and 50 parts of styrene were used instead of 100 parts of butyl acrylate, and a styrene-acrylonitrile macromonomer was used instead of the styrene macromonomer. It produced and measured the swelling degree and the glass transition temperature. The results are shown in Table 1.
- a polymer film, a slurry for positive electrode, and a battery were prepared in the same manner as in Example 1 except that graft polymer 8 was used instead of graft polymer 1 as a binder constituting the positive electrode. Then, the swelling degree of the polymer film, the glass transition temperature, the sedimentation property in the positive electrode slurry, the rate characteristics of the battery, and the gas generation were evaluated. The results are shown in Tables 1 and 2.
- graft polymer 9 Polymerization was conducted by heating to obtain a polymer solution (hereinafter referred to as “graft polymer 9”).
- the polymerization conversion rate determined from the solid content concentration was approximately 98%.
- the graft polymer 9 had a weight average molecular weight of about 10,000.
- a polymer film, a slurry for positive electrode, and a battery were prepared in the same manner as in Example 1 except that graft polymer 9 was used instead of graft polymer 1 as a binder constituting the positive electrode. Then, the swelling degree of the polymer film, the glass transition temperature, the sedimentation property in the positive electrode slurry, the rate characteristics of the battery, and the gas generation were evaluated. The results are shown in Tables 1 and 2.
- a polymer film of segment A and segment B was prepared in the same manner as in Example 1 except that 50 parts of butyl acrylate and 50 parts of styrene were used instead of 100 parts of butyl acrylate, and the degree of swelling and the glass transition temperature were measured. . The results are shown in Table 1.
- a polymer film, a slurry for positive electrode, and a battery were prepared in the same manner as in Example 1 except that the graft polymer 10 was used instead of the graft polymer 1 as a binder constituting the positive electrode. Then, the swelling degree of the polymer film, the glass transition temperature, the sedimentation property in the positive electrode slurry, the rate characteristics of the battery, and the gas generation were evaluated. The results are shown in Tables 1 and 2.
- a polymer film of segment A and segment B was prepared in the same manner as in Example 1 except that 33.3 parts of ethylene and 66.7 parts of ethyl acrylate were used instead of 100 parts of butyl acrylate. Measurements were made. The results are shown in Table 1.
- a polymer film, a slurry for a positive electrode, and a battery were prepared in the same manner as in Example 1 except that the graft polymer 11 was used instead of the graft polymer 1 as a binder constituting the positive electrode. Then, the swelling degree of the polymer film, the glass transition temperature, the sedimentation property in the positive electrode slurry, the rate characteristics of the battery, and the gas generation were evaluated. The results are shown in Tables 1 and 2.
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Secondary Cells (AREA)
Abstract
Description
また、特許文献2には、オレフィンとアクリロニトリルからなるグラフトポリマーを正極電極中に使用することが開示されており、電解液への膨潤性を抑えることで活物質との結着性を維持し、サイクル特性に優れた電池が得られている。
従って、本発明の目的は、得られる二次電池が高い出力特性を有し、ガス発生が抑制されたリチウムイオン二次電池用電極を提供することにある。
(1)集電体、及び前記集電体上に積層された、活物質及び結着剤を含有する電極活物質層を含み、前記結着剤として、電解液に対する膨潤度が100~300%であるセグメントAと、電解液に対する膨潤度が500~50,000%であるかまたは電解液に溶解するセグメントBとからなるグラフトポリマーを含むことを特徴とする二次電池用電極。
(2)前記グラフトポリマーにおける前記セグメントAと前記セグメントBとの比率が、20:80~80:20(質量比)である前記(1)記載の二次電池用電極。
(3)前記グラフトポリマーの重量平均分子量が1,000~500,000の範囲にある前記(1)~(2)のいずれかに記載の二次電池用電極。
(4)前記セグメントBが、ガラス転移温度15℃以下の軟質重合体のセグメントである前記(1)~(3)のいずれかに記載の二次電池用電極。
(5)電解液に対する膨潤度が100~300%であるセグメントAと、電解液に対する膨潤度が500~50,000%であるかまたは電解液に溶解するセグメントBとからなるグラフトポリマーを含むことを特徴とする二次電池用結着剤。
(6)前記グラフトポリマーにおける前記セグメントAと前記セグメントBとの比率が、20:80~80:20(質量比)である前記(5)記載の二次電池用結着剤。
(7)前記セグメントBが、ガラス転移温度15℃以下の軟質重合体のセグメントである前記(5)~(6)のいずれかに記載の二次電池用結着剤。
(8)電解液に対する膨潤度が100~300%であるセグメントAと、電解液に対する膨潤度が500~50,000%であるかまたは電解液に溶解するセグメントBとからなるグラフトポリマー、活物質及び溶媒を含むスラリーを、集電体上に塗布し、乾燥する工程を含む前記(1)記載の二次電池用電極の製造方法。
(9)正極、電解液及び負極を有するリチウムイオン二次電池であって、前記正極及び負極の少なくともいずれかが、前記(1)~(4)のいずれかに記載の二次電池用電極であることを特徴とする、二次電池。
本発明の二次電池用電極(以下、単に「電極」ということがある。)は、活物質及び結着剤を含有してなる電極活物質層が、集電体上に積層されてなる。即ち、本発明の電極は、集電体、及び前記集電体上に積層された、活物質及び結着剤を含有する電極活物質層を含む。本発明の電極は、前記結着剤として、電解液に対する膨潤度が100~300%であるセグメントAと、電解液に対する膨潤度が500~50,000%であるかまたは電解液に溶解するセグメントBとからなるグラフトポリマーを含む。
(電極活物質)
本発明の二次電池用電極に用いられる電極活物質は、一般的に、電極が利用される二次電池に応じて選択される。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を用いることもできる。電気伝導性に乏しい、鉄系酸化物は、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。
本発明の二次電池用電極は、結着剤として、電解液に対する膨潤度が100~300%であるセグメントAと、電解液に対する膨潤度が500~50,000%であるかまたは電解液に溶解するセグメントBとからなるグラフトポリマーを含む。
本発明に用いるグラフトポリマーは、二つのセグメント(セグメントA、セグメントB)を有し、その一方のセグメントが主鎖を構成し、他方がグラフト部(側鎖)を構成する分岐型構造を有する。グラフトポリマーは、第一セグメント及び第二セグメントを備えるのに加え、さらに1以上の任意のセグメントを備えうる。また、第一セグメント及び第二セグメントのそれぞれは、一種類のみの重合単位に基づくセグメントであってもよく、二種類以上の重合単位に基づくセグメントであってもよい。
本発明に用いるグラフトポリマーは、二つのセグメントのいずれが主鎖を構成しても、グラフト部(側鎖)を構成してもよい。その中でもスラリー中にて高膨潤のセグメントBがスラリー溶媒中に広がり、低膨潤のセグメントAが活物質及び導電剤への吸着することにより高い導電剤分散性と活物質保護効果を示すことから、特に側鎖が低膨潤のセグメントAからなる構造が好ましい。従って、セグメントAがグラフト部(側鎖)を構成し、セグメントBが主鎖を構成するグラフトポリマーが好ましい。
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、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。
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。
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、電解液に対する膨潤度を100~300%とするためには、溶解度パラメーターが8.0未満あるいは11以上である単量体成分、または疎水性部を有する単量体成分で構成するのが好ましい。また、膨潤度を重量平均分子量により制御する場合は、セグメントAの重量平均分子量を4,000以上10,000以下とするのが好ましい。重量平均分子量を本範囲に入るようにすることにより、導電剤や活物質への分散性及びスラリー安定性を向上させることができる。本発明において重量平均分子量はゲルパーミエーションクロマトグラフィー(GPC)で測定されるポリスチレン換算重量平均分子量をいう。
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
本発明においては、膨潤度が100~300%であるセグメントAとしては、電解液への膨潤性を全く示さないことからα,β-不飽和ニトリル化合物及びスチレン系単量体が好ましい。更には導電剤の分散性が高いことからスチレン系単量体が最も好ましい。
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、電解液に対する膨潤度を500~50,000%とするためには、溶解度パラメーターが8.0以上11未満である単量体成分、または親水性基を有する単量体成分で構成するのが好ましい。また、膨潤度を重量平均分子量により制御する場合は、セグメントBの重量平均分子量を10,000以上500,000以下とするのが好ましい。重量平均分子量を本範囲に入るようにすることにより、高い結着性を有し、電極活物質層の剥がれ等を生じない。
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。
なお、セグメントのガラス転移温度は、例示の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を組み合わせることによって調整可能である。
電解液に対する膨潤度は、分子量が小さいほど大きくなり、分子量が大きいほど小さくなる傾向にある。従って、好適な膨潤度とするためのグラフトポリマーの重量平均分子量の範囲は、その構造、架橋度などにより異なるが、例えば、テトラヒドロフラン(THF)を展開溶媒としたゲル・パーミエーション・クロマトグラフィーで測定した標準ポリスチレン換算値で1,000~500,000、更に好ましくは2,000~100,000である。グラフトポリマーの重量平均分子量を上記範囲とすることにより、セグメントA及びセグメントBが所定の膨潤性を示し高いレート特性とガス発生抑制効果を示す。
グラフト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グラフト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グラフトポリマーとする方法としては、グラフト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1)分岐構造を構成するように共重合させる方法としては、例えば、幹ポリマーの存在下にグラフトモノマーを公知の重合法により重合することで連鎖移動反応によりグラフトポリマーを得ることができる。また、幹ポリマー中にラジカルやイオンを発生し得る官能基を導入し、該官能基からグラフトモノマーの重合反応を開始させることによりグラフトポリマーを得ることもできる。そのほか、重合時に分岐構造を形成しうるグラフトモノマーを公知の重合法により重合して得た枝ポリマーを、ラジカル付加反応などにより幹ポリマーに付加させてもよい。具体的には、特公平6-51767号公報などに記載された方法によってグラフトポリマーを製造することができる。
これらの中でも、特に重合時に分岐構造を形成しうるグラフトモノマーを公知の重合法により重合して得た枝ポリマーを、ラジカル付加反応などにより幹ポリマーに付加させる方法が最も構造制御が容易であり、後述する二次電池電極用スラリーを安定化し易いので好ましい。具体的には枝ポリマーとしてマクロモノマーを用いて共重合させる方法があげられる。
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、好ましくはグラフト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。
更に、下に例示する軟質重合体も結着剤として使用することができる。
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、アクリル系軟質重合体;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系軟質重合体;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系軟質重合体;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系軟質重合体;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系軟質重合体;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系軟質重合体;フッ化ビニリデン系ゴム、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、ポリエステル系熱可塑性エラストマー、塩化ビニル系熱可塑性エラストマー、ポリアミド系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。これらは単独で用いてもよく、2種以上を組み合わせて用いてもよい。
中でも、ポリアクリロニトリル誘導体が活物質の分散性を向上させるために好ましい。その他結着剤の含有割合は、全結着剤量を100質量%として、好ましくは5質量%以上80質量%以下、更に好ましくは10質量%以上70質量%以下、最も好ましくは20質量%以上60質量%以下である。その他結着剤が上記範囲に入ることにより電池内部の抵抗が上がることがなく高い寿命特性を示すことが出来る。
本発明の二次電池用電極は活物質及び結着剤を含む電極活物質層が、集電体上に積層されてなる。
集電体は、電気導電性を有しかつ電気化学的に耐久性のある材料であれば特に制限されないが、耐熱性を有するとの観点から、例えば、鉄、銅、アルミニウム、ニッケル、ステンレス鋼、チタン、タンタル、金、白金などの金属材料が好ましい。中でも、リチウムイオン二次電池の正極用としてはアルミニウムが特に好ましく、リチウムイオン二次電池の負極用としては銅が特に好ましい。集電体の形状は特に制限されないが、厚さ0.001~0.5mm程度のシート状のものが好ましい。集電体は、電極の接着強度を高めるため、予め粗面化処理して使用するのが好ましい。粗面化方法としては、機械的研磨法、電解研磨法、化学研磨法などが挙げられる。機械的研磨法においては、研磨剤粒子を固着した研磨布紙、砥石、エメリバフ、鋼線などを備えたワイヤーブラシ等が使用される。また、電極の接着強度や導電性を高めることを目的に、集電体表面に中間層を形成してもよい。
本発明に用いる二次電池電極用スラリーは、グラフトポリマーを含む結着剤、活物質、及び溶媒を含む。グラフトポリマーを含む結着剤、活物質としては、二次電池用電極で説明したものと同様のものが挙げられる。
溶媒としては、本発明の結着剤を均一に溶解または分散し得るものであれば特に制限されない。
二次電池電極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系脂肪族炭化水素;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、本発明の重合体の溶解性に優れ、電極活物質及び導電剤の分散性にすぐれ、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。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。
固形分以外の成分は、乾燥の工程により揮発する成分であり、前記溶媒に加え、例えば、グラフトポリマーの調製及び添加に際しこれらを溶解または分散させていた媒質をも含む。
本発明の二次電池電極用スラリーは、本発明の二次電池用電極を形成するためのものであるので、二次電池電極用スラリーの固形分全量中の、電極活物質及びグラフトポリマーの含有割合は、当然ながら、本発明の二次電池用電極の電極活物質層について上述した通りとされる。
本発明においては、二次電池電極用スラリーの製法は、特に限定はされず、グラフトポリマーを含む結着剤、活物質、及び溶媒と必要に応じ添加される他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、電極活物質と導電剤が高度に分散された電極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、ビーズミル、ボールミル、ロールミル、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、フィルミックスなどを使用することができるが、中でも高濃度での分散が可能なことから、ボールミル、ロールミル、顔料分散機、擂潰機、プラネタリーミキサーを使用することが特に好ましい。
二次電池電極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~100,000mPa・s、更に好ましくは100~50,000mPa・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。
本発明の二次電池は、正極、負極、セパレーター及び電解液を含み、前記正極及び負極の少なくともいずれかが、前記二次電池用電極である。中でも、導電剤と活物質を併用して用いることが多く、導電剤の分散性不良によるレート特性の低下が多く見られること、更には電位が高いことによる活物質表面での電解液の反応が起こりやすくガス発生が多く見られることから、正極に用いた際に大きな効果を得ることができる。
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二次電池電極用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系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。
セパレーターとしては、ポリエチレン、ポリプロピレンなどのポリオレフィン製の微孔膜または不織布;無機セラミック粉末を含む多孔質の樹脂コート;など公知のものを用いることができる。リチウムイオン二次電池用セパレーターとしては、ポリエチレン、ポリプロピレンなどのポリオレフィン樹脂や芳香族ポリアミド樹脂を含む微孔膜または不織布;無機セラミック粉末を含む多孔質の樹脂コート;など公知のものを用いることができる。例えばポリオレフィン系(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系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、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、ポリオレフィン系の樹脂からなる微多孔膜が好ましい。
セパレーターの厚さは、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、また電池作成時の作業性に優れる。
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。
約0.1mm厚のポリマーのフィルムを約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、電解液をふき取ってすぐ重量(浸漬後重量)を測定し、(浸漬後重量)/(浸漬前重量)×100(%)の値を膨潤度とし、下記の基準により判定する。なお、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。前記膨潤度が小さいほど、ポリマーの耐電解液性が高いことを示す。
A:100%を超え200%以下
B:200%を超え300%以下
C:300%を超え500%以下
D:500%を超え700%以下
E:700%を超え1500%以下
F:1500%を超え50,000%以下
G:50,000%を超えるもしくは溶解する
直径1cmの試験管内に高さ(深さ)5cmまでスラリーを入れ、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本のサンプルの中で、最も早く沈降した日を沈降が見られた日とする。沈降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:2~5日後に沈降がみられる。
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。
ハーフセルコイン型のリチウムイオン二次電池について、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。これらの測定をハーフセルコイン型のリチウムイオン二次電池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、これをレート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(レート特性)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%以下
E:1%未満
ラミネートセル型のリチウム二次イオン電池について0.1Cの定電流法によって4.3Vまで充電した後、80℃で50時間保存する。ラミネートセル型リチウム二次イオン電池をガラス板にてセルを挟み、マイクロゲージにてセルの厚さを計測する。80℃保存前のセルの厚さをa、80℃50時間保存後のセルの厚さをbとし、80℃保存前後の厚さの比(b/a)を求め、以下の基準により判定する。
A:1.00倍以上1.05倍以下
B:1.05倍を超え1.10倍以下
C:1.10倍を超え1.15倍以下
D:1.15倍を超え1.20倍以下
E:1.20倍以上
得られたラミネートセル型電池のそれぞれを、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。充電後に3Vまで放電する。この定電流定電圧充電と放電のサイクルをもう1回繰り返し、その後0℃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。この定電流定電圧充電における定電流時に得られた電池容量をリチウム受け入れ性の指標とし、下記の基準で判定した。この値が大きいほど、リチウム受入性がよく、低温においても電池性能が低下しない電池であることを示す。
A:200mAh/g以上
B:180mAh/g以上200mAh/g未満
C:160mAh/g以上180mAh/g未満
D:140mAh/g以上160mAh/g未満
E:140mAh/g未満
<グラフトポリマーの作製>
撹拌機付きのオートクレーブに、トルエン230部、セグメントAとしてスチレンマクロモノマー(片末端メタクリロイル化ポリスチレンオリゴマー、東亜合成化学工業社製、「AS-6」)40部、セグメントBを構成する単量体としてブチルアクリレート60部、重合開始剤としてt-ブチルパーオキシ-2-エチルヘキサネート1部をそれぞれ入れ、十分に撹拌した後、90℃に加温して重合し、重合体(以下、「グラフトポリマー1」という。)の溶液を得た。固形分濃度から求めた重合転化率はほぼ98%であった。また、このグラフトポリマー1の重量平均分子量は約5万であった。重量平均分子量はゲルパーミエーションクロマトグラフィ(GPC)で測定し、標準ポリスチレン換算の重量平均分子量を求めた。GPCはHLC-8220(東ソー社製)を用いて行った。得られたグラフトポリマーは、主鎖がブチルアクリレート(電解液に対する膨潤性を示す成分)、側鎖がスチレン(電解液に対する膨潤性を示さない成分)で構成されていた。得られたグラフトポリマー1のトルエン溶液を120℃10時間窒素雰囲気下で乾燥し、ポリマーフィルムを作製し、膨潤度及びガラス転移温度の測定を行った。結果を表1に示す。
スチレンマクロモノマー(片末端メタクリロイル化ポリスチレンオリゴマー、東亜合成化学工業社製、「AS-6」)のトルエン溶液を120℃10時間窒素雰囲気下で乾燥し、セグメントAのポリマーフィルムを作製し、膨潤度、ガラス転移温度の測定を行った。結果を表1に示す。
撹拌機付きのオートクレーブに、トルエン230部、ブチルアクリレート100部、重合開始剤としてt-ブチルパーオキシ-2-エチルヘキサネート1部をそれぞれ入れ、十分に撹拌した後、90℃に加温して重合し、セグメントBからなる重合体の溶液を得た。得られた前記重合体溶液を120℃10時間窒素雰囲気下で乾燥し、セグメントBのポリマーフィルムを作製し、膨潤度、ガラス転移温度の測定を行った。結果を表1に示す。
得られたグラフトポリマー1のトルエン溶液をN-メチル-2-ピロリドン(以下NMPという。)溶液へ転相し、固形分濃度17.8%のグラフトポリマー1のNMP溶液を得た。
ディスパー付きのプラネタリーミキサーに正極活物質としてマンガン酸リチウム100部を入れ、これに導電剤としてアセチルブラック5部を加え混合した。得られた混合物に前記のグラフトポリマー1のNMP溶液(固形分濃度17.8%)を3.4部(グラフトポリマー1として1.2部)添加し、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分混合した。これを脱泡処理して艶のある流動性の良い正極用電極スラリーを得た。得られたスラリーの沈降性を評価した。結果を表2に示す。
上記正極用電極スラリーを厚さ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。
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負極用電極スラリーを調製した。この負極用電極スラリーを厚さ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の負極活物質層を有する負極を得た。
アルミニウムシートの両面がポリプロピレンからなる樹脂で被覆された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負極のそれぞれの端部から活物質層を除去し、露出した箔にタブを溶接した。タブとしては、正極はNiタブを、負極はCuタブを用いた。得られたタブ付きの正極及び負極、並びにポリエチレン製の微多孔膜からなるセパレーターを、両極の活物質層面が対向し、その間にセパレータが位置するように重ねた。得られた積層物を、捲回して上記の電池容器に収納した。続いて、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して電解液を調製した。この電解液を、電池容器に注入した。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。得られたラミネートセルのガス発生量を測定した。評価結果を表2に示す。
上記で得られた正極を直径13mmの円形に切り抜いた。負極として金属リチウム金属箔を直径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。円形の正極、金属リチウム金属箔及びセパレーターを、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)中に配置した。かかる配置により、正極電極の正極合剤層側の面と、負極の金属リチウム金属箔とが、セパレーターを介して対向し、外装容器底面に正極のアルミニウム箔が接した。更に負極の金属リチウム上にエキスパンドメタルを置き、外装容器中に収納した。この外装容器中に電解液(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のリチウムイオン二次電池を製造した(コインセルCR2032)。得られた電池についてレート特性を測定した。結果を表2に示す。
撹拌機付きのオートクレーブに、トルエン230部、セグメントAとしてスチレン-アクリロニトリルマクロモノマー(片末端メタクリロイル化ポリスチレン-アクリロニトリルオリゴマー、東亜合成化学工業社製、「AN-6S」)40部、セグメントBを構成する単量体としてアクリル酸ブチル60部、重合開始剤としてt-ブチルパーオキシ-2-エチルヘキサネート1部を入れ、十分に撹拌した後、90℃に加温して重合し、重合体(以下、「グラフトポリマー2」という。)の溶液を得た。固形分濃度から求めた重合転化率はほぼ98%であった。得られたグラフトポリマー2の重量平均分子量は約5万であった。得られたグラフトポリマー2は、主鎖がアクリル酸ブチル(電解液に対する膨潤性を示す成分)、側鎖がアクリロニトリルおよびスチレン(電解液に対する膨潤性を示さない成分)で構成されていた。
正極電極を構成する結着剤としてグラフトポリマー1のかわりにグラフトポリマー2を用いた他は、実施例1と同様にポリマーフィルム、正極電極用スラリー、及び電池を作製した。そして、ポリマーフィルムの膨潤度、ガラス転移温度、正極電極用スラリーにおける沈降性、電池のレート特性、及びガス発生量を評価した。結果を表1および表2に示す。
撹拌機付きのオートクレーブに、トルエン230部、セグメントBを構成する単量体としてアクリル酸エチル57部、グリシジルメタクリレートを3部、重合開始剤としてt-ブチルパーオキシ-2-エチルヘキサネート1部を入れ、十分に撹拌した後、80℃に加温して重合し、重合体溶液を得た。続けて、セグメントAを構成する成分として末端がカルボキシル基で変性されたポリアクリロニトリル40部を添加後、120℃に加温して変性し、熱変性重合体(以下、「グラフトポリマー3」という。)の溶液を得た。固形分濃度から求めた重合転化率はほぼ98%であった。また、このグラフトポリマー3の重量平均分子量は約7万であった。得られたグラフトポリマーは、主鎖がアクリル酸エチル(電解液に対する膨潤性を示す成分)、側鎖がアクリロニトリル(電解液に対する膨潤性を示さない成分)で構成されていた。
撹拌機付きのオートクレーブに、トルエン230部、セグメントAとしてスチレン-アクリロニトリルマクロモノマー(片末端メタクリロイル化ポリスチレン-アクリロニトリルオリゴマー、東亜合成化学工業社製、「AN-6S」)40部、セグメントBを構成する単量体としてアクリル酸n-エチル60部、重合開始剤としてt-ブチルパーオキシ-2-エチルヘキサネート1部、分子量調整剤としてn-ドデシルメルカプタンを0.05部入れ、十分に撹拌した後、90℃に加温して重合し、重合体(以下、「グラフトポリマー4」という。)の溶液を得た。固形分濃度から求めた重合転化率はほぼ98%であった。また、このグラフトポリマー4の重量平均分子量は約3万であった。得られたグラフトポリマーは、主鎖がアクリル酸n-エチル(電解液に対する膨潤性を示す成分)、側鎖がスチレン-アクリロニトリル(電解液に対する膨潤性を示さない成分)で構成されていた。
正極電極を構成する結着剤としてグラフトポリマー1のかわりにグラフトポリマー4を用いた他は、実施例1と同様にポリマーフィルム、正極電極用スラリー、及び電池を作製した。そして、ポリマーフィルムの膨潤度、ガラス転移温度、正極電極用スラリーにおける沈降性、電池のレート特性、及びガス発生を評価した。結果を表1および表2に示す。
<グラフトポリマーの作製>
撹拌機付きのオートクレーブに、トルエン230部、セグメントAとしてスチレンマクロモノマー(片末端メタクリロイル化ポリスチレンオリゴマー、東亜合成化学工業社製、「AS-6」)40部、セグメントBを構成する単量体としてブチルアクリレート58部、グリシジルメタクリレート2部、重合開始剤としてt-ブチルパーオキシ-2-エチルヘキサネート1部を入れ、十分に撹拌した後、90℃に加温して重合し、重合体(以下、「グラフトポリマー5」という。)の溶液を得た。固形分濃度から求めた重合転化率はほぼ98%であった。また、このグラフトポリマー5の重量平均分子量は約5万であった。得られたグラフトポリマーは、主鎖がブチルアクリレートとグリシジルメタクリレートの共重合体(電解液に対する膨潤性を示す成分)、側鎖がスチレン(電解液に対する膨潤性を示さない成分)で構成されていた。得られたグラフトポリマー5のトルエン溶液を120℃10時間窒素雰囲気下で乾燥し、ポリマーフィルムを作製し、膨潤度の測定を行った。結果を表1に示す。
スチレンマクロモノマー(片末端メタクリロイル化ポリスチレンオリゴマー、東亜合成化学工業社製、「AS-6」)のトルエン溶液を120℃10時間窒素雰囲気下で乾燥し、セグメントAのポリマーフィルムを作製し、膨潤度、ガラス転移温度の測定を行った。結果を表1に示す。
撹拌機付きのオートクレーブに、トルエン230部、ブチルアクリレート96.3部、グリシジルメタクリレート3.3部、重合開始剤としてt-ブチルパーオキシ-2-エチルヘキサネート1部を入れ、十分に撹拌した後、90℃に加温して重合し、セグメントBからなる重合体の溶液を得た。得られたセグメントBからなる重合体のトルエン溶液を120℃10時間窒素雰囲気下で乾燥し、セグメントBのポリマーフィルムを作製し、膨潤度、ガラス転移温度の測定を行った。結果を表3に示す。
得られたグラフトポリマー5のトルエン溶液をNMP溶液へ転相し、固形分濃度17.8%のグラフトポリマー5のNMP溶液を得た。
ディスパー付きのプラネタリーミキサーに正極活物質としてマンガン酸リチウム100部を入れ、これに導電剤としてアセチルブラック5部を加え混合した。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部を添加し、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分混合した。これを脱泡処理して正極用電極スラリーを得た。
上記正極用電極スラリーを厚さ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。
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、結着剤としてグラフトポリマー5を固形分相当で1.6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負極用電極スラリーを調製した。この負極用電極スラリーを厚さ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の負極活物質層を有する負極を得た。
アルミニウムシートの両面がポリプロピレンからなる樹脂で被覆された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負極のそれぞれの端部から活物質層を除去し、露出した箔にタブを溶接した。タブとしては、正極はNiタブを、負極はCuタブを用いた。得られたタブ付きの正極及び負極、並びにポリエチレン製の微多孔膜からなるセパレーターを、両極の活物質層面が対向し、その間にセパレータが位置するように重ねた。得られた積層物を、捲回して上記の電池容器に収納した。続いて、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して電解液を調製した。この電解液を、電池容器に注入した。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。得られたラミネートセルのリチウム低温受け入れ特性を評価した。評価結果を表3に示す。
撹拌機付きのオートクレーブに、トルエン230部、セグメントAとしてスチレンマクロモノマー(片末端メタクリロイル化ポリスチレンオリゴマー、東亜合成化学工業社製、「AS-6」)40部、セグメントBを構成する単量体としてアクリル酸n-エチル50部、アクリロニトリル10部、重合開始剤としてt-ブチルパーオキシ-2-エチルヘキサネート1部を入れ、十分に撹拌した後、90℃に加温して重合し、重合体(以下、「グラフトポリマー6」という。)の溶液を得た。固形分濃度から求めた重合転化率はほぼ98%であった。また、このグラフトポリマー6の重量平均分子量は約5万であった。得られたグラフトポリマーは、主鎖がアクリル酸n-エチルとアクリロニトリルの共重合体(電解液に対する膨潤性を示す成分)、側鎖がスチレン(電解液に対する膨潤性を示さない成分)で構成されていた。
正極電極を構成する結着剤としてグラフトポリマー5のかわりにグラフトポリマー6を用いた他は、実施例5と同様にポリマーフィルム、負極電極用スラリー、及び電池を作製した。そして、ポリマーフィルムの膨潤度、及びリチウム低温受け入れ特性を評価した。結果を表1、3に示す。
撹拌機付きのオートクレーブに、トルエン230部、セグメントAとして合成したブチロアクリレートマクロモノマー(片末端メタクリロイル化ポリスチレンオリゴマー、東亜合成化学工業社製、「AB-6」)40部、セグメントBを構成する単量体としてビニルピロリドン60部、重合開始剤としてt-ブチルパーオキシ-2-エチルヘキサネート1部を入れ、十分に撹拌した後、90℃に加温して重合し、重合体(以下、「グラフトポリマー7」という。)の溶液を得た。固形分濃度から求めた重合転化率はほぼ98%であった。また、このグラフトポリマー7の重量平均分子量は約5万であった。
撹拌機付きのオートクレーブに、トルエン230部、セグメントAとしてスチレン-アクリロニトリルマクロモノマー(片末端メタクリロイル化ポリスチレン-アクリロニトリルオリゴマー、東亜合成化学工業社製、「AN-6S」)40部、セグメントBを構成する単量体としてブチルアクリレート30部、スチレン30部、重合開始剤としてt-ブチルパーオキシ-2-エチルヘキサネート1部を入れ、十分に撹拌した後、90℃に加温して重合し、重合体(以下、「グラフトポリマー8」という。)の溶液を得た。固形分濃度から求めた重合転化率はほぼ98%であった。また、このグラフトポリマー8の重量平均分子量は約5万であった。
撹拌機付きのオートクレーブに、トルエン230部、セグメントAとしてブチルアクリレートマクロモノマー(片末端メタクリロイル化ポリアブチルアクリレートオリゴマー、東亜合成化学工業社製、「AB-6」)40部、セグメントBを構成する単量体としてブチルアクリレート60部、重合開始剤としてt-ブチルパーオキシ-2-エチルヘキサネート1部、分子量調整剤としてn-ドデシルメルカプタン0.5部を入れ、十分に撹拌した後、90℃に加温して重合し、重合体(以下、「グラフトポリマー9」という。)の溶液を得た。固形分濃度から求めた重合転化率はほぼ98%であった。また、このグラフトポリマー9の重量平均分子量は約1万であった。
撹拌機付きのオートクレーブに、トルエン230部、セグメントAとしてスチレンマクロモノマー(片末端メタクリロイル化ポリスチレンオリゴマー、東亜合成化学工業社製、「AS-6」)40部、セグメントBを構成する単量体としてブチルアクリレート30部及びスチレン30部、並びに重合開始剤としてt-ブチルパーオキシ-2-エチルヘキサネート1部を入れ、十分に撹拌した後、90℃に加温して重合し、重合体(以下、「グラフトポリマー10」という。)の溶液を得た。固形分濃度から求めた重合転化率はほぼ98%であった。また、このグラフトポリマー10の重量平均分子量は約5万であった。
撹拌機付きのオートクレーブに、トルエン230部、セグメントAとしてスチレンマクロモノマー(片末端メタクリロイル化ポリスチレンオリゴマー、東亜合成化学工業社製、「AS-6」)40部、セグメントBを構成する単量体としてエチレン20部及びエチルアクリレート40部、並びに重合開始剤としてt-ブチルパーオキシ-2-エチルヘキサネート1部を入れ、十分に撹拌した後、90℃に加温して重合し、重合体(以下、「グラフトポリマー11」という。)の溶液を得た。固形分濃度から求めた重合転化率はほぼ98%であった。また、このグラフトポリマー11のガラス転移温度は10℃、重量平均分子量は約5万であった。
また、表3より、このグラフトポリマーを負極を構成する結着剤として用いることで、リチウム低温受け入れ特性が向上することが明らかとなった。
Claims (9)
- 集電体、及び前記集電体上に積層された、活物質及び結着剤を含有する電極活物質層を含み、前記結着剤として、電解液に対する膨潤度が100~300%であるセグメントAと、電解液に対する膨潤度が500~50,000%であるかまたは電解液に溶解するセグメントBとからなるグラフトポリマーを含むことを特徴とする二次電池用電極。
- 前記グラフトポリマーにおける前記セグメントAと前記セグメントBとの比率が、20:80~80:20(質量比)である請求項1記載の二次電池用電極。
- 前記グラフト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電極。
- 前記セグメントBが、ガラス転移温度15℃以下の軟質重合体のセグメントである請求項1に記載の二次電池用電極。
- 電解液に対する膨潤度が100~300%であるセグメントAと、電解液に対する膨潤度が500~50,000%であるかまたは電解液に溶解するセグメントBとからなるグラフトポリマーを含むことを特徴とする二次電池用結着剤。
- 前記グラフトポリマーにおける前記セグメントAと前記セグメントBとの比率が、20:80~80:20(質量比)である請求項5記載の二次電池用結着剤。
- 前記セグメントBが、ガラス転移温度15℃以下の軟質重合体のセグメントである請求項5~6のいずれかに記載の二次電池用結着剤。
- 電解液に対する膨潤度が100~300%であるセグメントAと、電解液に対する膨潤度が500~50,000%であるかまたは電解液に溶解するセグメントBとからなるグラフトポリマー、活物質及び溶媒を含むスラリーを、集電体上に塗布し、乾燥する工程を含む請求項1記載の二次電池用電極の製造方法。
- 正極、電解液及び負極を有するリチウムイオン二次電池であって、
前記正極及び負極の少なくともいずれかが、請求項1に記載の二次電池用電極であることを特徴とする、二次電池。
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2011520870A JP5621772B2 (ja) | 2009-06-30 | 2010-06-22 | 二次電池用電極及び二次電池 |
CN201080029217.5A CN102473917B (zh) | 2009-06-30 | 2010-06-22 | 二次电池用电极及二次电池 |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2009156249 | 2009-06-30 | ||
JP2009-156249 | 2009-06-30 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2011001848A1 true WO2011001848A1 (ja) | 2011-01-06 |
Family
ID=43410925
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2010/060565 WO2011001848A1 (ja) | 2009-06-30 | 2010-06-22 | 二次電池用電極及び二次電池 |
Country Status (4)
Country | Link |
---|---|
JP (1) | JP5621772B2 (ja) |
KR (1) | KR101539819B1 (ja) |
CN (1) | CN102473917B (ja) |
WO (1) | WO2011001848A1 (ja) |
Cited By (29)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2013031690A1 (ja) * | 2011-08-30 | 2013-03-07 | 日本ゼオン株式会社 | 二次電池負極用バインダー組成物、二次電池用負極、負極用スラリー組成物、製造方法及び二次電池 |
JP2013213201A (ja) * | 2012-03-08 | 2013-10-17 | Waseda Univ | ベンゾジチオフェンキノンポリマー、電荷貯蔵材料、電極活物質、電極、及び電池 |
WO2014024937A1 (ja) * | 2012-08-09 | 2014-02-13 | 日本ゼオン株式会社 | 二次電池用負極、二次電池、スラリー組成物、及び製造方法 |
WO2014088070A1 (ja) * | 2012-12-05 | 2014-06-12 | 日本ゼオン株式会社 | リチウムイオン二次電池 |
JP2014123488A (ja) * | 2012-12-21 | 2014-07-03 | Sumitomo Metal Mining Co Ltd | 二次電池の発生ガス量の評価方法 |
EP2765633A1 (en) * | 2013-02-12 | 2014-08-13 | Jtekt Corporation | Production apparatus and production method for electric storage material |
WO2014148064A1 (ja) * | 2013-03-22 | 2014-09-25 | 日本ゼオン株式会社 | リチウムイオン二次電池負極用スラリー組成物、リチウムイオン二次電池用負極およびリチウムイオン二次電池 |
WO2015005151A1 (ja) * | 2013-07-10 | 2015-01-15 | 日本ゼオン株式会社 | リチウムイオン二次電池用多孔膜組成物、リチウムイオン二次電池用セパレータ、リチウムイオン二次電池用電極、及びリチウムイオン二次電池 |
WO2015005145A1 (ja) * | 2013-07-10 | 2015-01-15 | 日本ゼオン株式会社 | リチウムイオン二次電池用接着剤、リチウムイオン二次電池用セパレータ、及びリチウムイオン二次電池 |
WO2015053224A1 (ja) * | 2013-10-09 | 2015-04-16 | 電気化学工業株式会社 | 正極用バインダー組成物、正極用スラリー、正極及びリチウムイオン二次電池 |
JP2015088253A (ja) * | 2013-10-28 | 2015-05-07 | 日本ゼオン株式会社 | リチウムイオン二次電池用接着剤、リチウムイオン二次電池用セパレータ及びリチウムイオン二次電池 |
WO2015174036A1 (ja) * | 2014-05-14 | 2015-11-19 | 日本ゼオン株式会社 | 二次電池電極用バインダー組成物、二次電池電極用スラリー組成物、二次電池用電極およびその製造方法、並びに、二次電池 |
WO2016017066A1 (ja) * | 2014-07-30 | 2016-02-04 | 日本ゼオン株式会社 | 非水系二次電池機能層用組成物、非水系二次電池用機能層付き基材、非水系二次電池用積層体の製造方法および非水系二次電池 |
JP2016024866A (ja) * | 2014-07-16 | 2016-02-08 | 日本ゼオン株式会社 | 非水系二次電池多孔膜用複合粒子、非水系二次電池用多孔膜、非水系二次電池用電池部材、および非水系二次電池 |
WO2016024383A1 (ja) * | 2014-08-11 | 2016-02-18 | 日本ゼオン株式会社 | 二次電池電極用バインダー組成物、二次電池電極用スラリー組成物、二次電池用電極および二次電池 |
WO2016031163A1 (ja) * | 2014-08-28 | 2016-03-03 | 日本ゼオン株式会社 | 非水系二次電池用積層体および非水系二次電池部材の製造方法 |
WO2016051674A1 (ja) * | 2014-09-29 | 2016-04-07 | 日本ゼオン株式会社 | 電気化学素子用接着剤組成物、電気化学素子用接着層、および電気化学素子 |
JP2016094581A (ja) * | 2014-11-17 | 2016-05-26 | パナック株式会社 | 固体高分子型燃料電池シール材用の樹脂組成物及び該樹脂組成物を用いた固体高分子型燃料電池用のシール材 |
WO2016110894A1 (ja) * | 2015-01-09 | 2016-07-14 | 日本ゼオン株式会社 | 非水系二次電池用セパレータおよびその製造方法、並びに、非水系二次電池 |
KR20170023788A (ko) * | 2014-06-27 | 2017-03-06 | 니폰 제온 가부시키가이샤 | 비수계 이차전지 기능층용 조성물, 비수계 이차전지용 기능층 및 비수계 이차전지 |
US9662806B2 (en) | 2014-02-26 | 2017-05-30 | Jtekt Corporation | Kneading device |
WO2017094252A1 (ja) * | 2015-11-30 | 2017-06-08 | 日本ゼオン株式会社 | 非水系二次電池接着層用組成物、非水系二次電池用接着層、積層体および非水系二次電池 |
JPWO2017155059A1 (ja) * | 2016-03-10 | 2019-01-10 | 日本ゼオン株式会社 | 非水系二次電池電極用バインダー、非水系二次電池電極用スラリー、非水系二次電池用電極、および非水系二次電池 |
US10374217B2 (en) | 2014-02-26 | 2019-08-06 | Jtekt Corporation | Apparatus and process for producing electricity storage material |
WO2019159706A1 (ja) * | 2018-02-19 | 2019-08-22 | 日本ゼオン株式会社 | 非水系二次電池電極用バインダー組成物、非水系二次電池電極用スラリー組成物、非水系二次電池用電極および非水系二次電池 |
JP2021046491A (ja) * | 2019-09-18 | 2021-03-25 | 株式会社日本触媒 | グラフト共重合体の製造方法 |
US11552297B2 (en) | 2014-06-04 | 2023-01-10 | Zeon Corporation | Binder composition for lithium ion secondary battery electrode-use, slurry composition for lithium ion secondary battery electrode-use, electrode for lithium ion secondary battery-use, and lithium ion secondary battery |
CN116948128A (zh) * | 2023-09-20 | 2023-10-27 | 宁德时代新能源科技股份有限公司 | 接枝聚合物、制备方法、正极极片、二次电池和用电装置 |
WO2024124424A1 (zh) * | 2022-12-14 | 2024-06-20 | 江阴纳力新材料科技有限公司 | 导电粘结剂及其制备方法、集流体、电极和电池 |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103351448B (zh) * | 2013-06-28 | 2015-12-23 | 中国科学院青岛生物能源与过程研究所 | 一种耐高温型锂离子二次电池粘合剂及制备方法 |
US10566628B2 (en) * | 2014-04-02 | 2020-02-18 | Zeon Corporation | Slurry for lithium ion secondary battery positive electrode-use, method for producing slurry for lithium ion secondary battery positive electrode-use, method for producing positive electrode for lithium ion secondary battery-use, and lithium ion secondary battery |
US10050246B2 (en) | 2014-12-26 | 2018-08-14 | Samsug SDI Co., Ltd. | Binder for rechargeable battery, separator for rechargeable battery including same, and rechargeable battery including same |
CN111406340B (zh) * | 2017-11-17 | 2024-01-16 | 富士胶片株式会社 | 固体电解质组合物、片材、电极片、电池及制造方法 |
JP7347218B2 (ja) * | 2018-02-09 | 2023-09-20 | 株式会社レゾナック | 非水系電池電極用スラリー、並びに非水系電池電極及び非水系電池の製造方法 |
EP3771003A4 (en) * | 2018-03-23 | 2022-02-09 | Zeon Corporation | NON-WATER SECONDARY BATTERY ELECTRODE BINDER COMPOSITION, NON-WATER SECONDARY BATTERY ELECTRODE CONDUCTIVE MATERIAL PASTE COMPOSITION, NON-WATER SECONDARY BATTERY ELECTRODE SLURRY COMPOSITION, NON-WATER SECONDARY BATTERY ELECTRODE, AND NON-WATER SECONDARY BATTERY ELECTRODE |
US20220045360A1 (en) * | 2018-12-28 | 2022-02-10 | Zeon Corporation | Binder composition for all-solid-state secondary battery |
CN112563453A (zh) * | 2020-12-10 | 2021-03-26 | 珠海冠宇电池股份有限公司 | 一种负极片及包括该负极片的锂离子电池 |
CN114388869A (zh) * | 2021-12-23 | 2022-04-22 | 荣盛盟固利新能源科技股份有限公司 | 一种凝胶聚合物电池及其制备方法 |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH1021926A (ja) * | 1996-07-05 | 1998-01-23 | Sumitomo Bakelite Co Ltd | 非水電解液二次電池用電極フィルム |
JPH1167274A (ja) * | 1997-08-22 | 1999-03-09 | Daikin Ind Ltd | リチウム二次電池及び高分子ゲル電解質並びにリチウム二次電池用結着剤 |
JP2003203676A (ja) * | 2000-11-21 | 2003-07-18 | Dainichiseika Color & Chem Mfg Co Ltd | 電池用電解質溶液の固形化材および電池 |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN1086516C (zh) * | 1997-09-19 | 2002-06-19 | 中国科学院化学研究所 | 一种锂电池正极材料及其制备方法和用途 |
-
2010
- 2010-06-22 JP JP2011520870A patent/JP5621772B2/ja not_active Expired - Fee Related
- 2010-06-22 KR KR1020117030261A patent/KR101539819B1/ko active IP Right Grant
- 2010-06-22 CN CN201080029217.5A patent/CN102473917B/zh active Active
- 2010-06-22 WO PCT/JP2010/060565 patent/WO2011001848A1/ja active Application Filing
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH1021926A (ja) * | 1996-07-05 | 1998-01-23 | Sumitomo Bakelite Co Ltd | 非水電解液二次電池用電極フィルム |
JPH1167274A (ja) * | 1997-08-22 | 1999-03-09 | Daikin Ind Ltd | リチウム二次電池及び高分子ゲル電解質並びにリチウム二次電池用結着剤 |
JP2003203676A (ja) * | 2000-11-21 | 2003-07-18 | Dainichiseika Color & Chem Mfg Co Ltd | 電池用電解質溶液の固形化材および電池 |
Cited By (63)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2013031690A1 (ja) * | 2011-08-30 | 2013-03-07 | 日本ゼオン株式会社 | 二次電池負極用バインダー組成物、二次電池用負極、負極用スラリー組成物、製造方法及び二次電池 |
JPWO2013031690A1 (ja) * | 2011-08-30 | 2015-03-23 | 日本ゼオン株式会社 | 二次電池負極用バインダー組成物、二次電池用負極、負極用スラリー組成物、製造方法及び二次電池 |
US10224549B2 (en) | 2011-08-30 | 2019-03-05 | Zeon Corporation | Binder composition for secondary battery negative electrode, negative electrode for secondary battery, negative electrode slurry composition, manufacturing method, and secondary battery |
JP2013213201A (ja) * | 2012-03-08 | 2013-10-17 | Waseda Univ | ベンゾジチオフェンキノンポリマー、電荷貯蔵材料、電極活物質、電極、及び電池 |
WO2014024937A1 (ja) * | 2012-08-09 | 2014-02-13 | 日本ゼオン株式会社 | 二次電池用負極、二次電池、スラリー組成物、及び製造方法 |
JPWO2014024937A1 (ja) * | 2012-08-09 | 2016-07-25 | 日本ゼオン株式会社 | 二次電池用負極、二次電池、スラリー組成物、及び製造方法 |
WO2014088070A1 (ja) * | 2012-12-05 | 2014-06-12 | 日本ゼオン株式会社 | リチウムイオン二次電池 |
JPWO2014088070A1 (ja) * | 2012-12-05 | 2017-01-05 | 日本ゼオン株式会社 | リチウムイオン二次電池 |
JP2014123488A (ja) * | 2012-12-21 | 2014-07-03 | Sumitomo Metal Mining Co Ltd | 二次電池の発生ガス量の評価方法 |
EP2765633A1 (en) * | 2013-02-12 | 2014-08-13 | Jtekt Corporation | Production apparatus and production method for electric storage material |
US9531007B2 (en) | 2013-02-12 | 2016-12-27 | Jtekt Corporation | Production apparatus and production method for electric storage material |
WO2014148064A1 (ja) * | 2013-03-22 | 2014-09-25 | 日本ゼオン株式会社 | リチウムイオン二次電池負極用スラリー組成物、リチウムイオン二次電池用負極およびリチウムイオン二次電池 |
JPWO2014148064A1 (ja) * | 2013-03-22 | 2017-02-16 | 日本ゼオン株式会社 | リチウムイオン二次電池負極用スラリー組成物、リチウムイオン二次電池用負極およびリチウムイオン二次電池 |
US10566627B2 (en) | 2013-03-22 | 2020-02-18 | Zeon Corporation | Slurry composition for negative electrode for lithium-ion secondary battery, negative electrode for lithium-ion secondary battery, and lithium-ion secondary battery |
WO2015005145A1 (ja) * | 2013-07-10 | 2015-01-15 | 日本ゼオン株式会社 | リチウムイオン二次電池用接着剤、リチウムイオン二次電池用セパレータ、及びリチウムイオン二次電池 |
JPWO2015005151A1 (ja) * | 2013-07-10 | 2017-03-02 | 日本ゼオン株式会社 | リチウムイオン二次電池用多孔膜組成物、リチウムイオン二次電池用セパレータ、リチウムイオン二次電池用電極、及びリチウムイオン二次電池 |
KR102211534B1 (ko) | 2013-07-10 | 2021-02-02 | 제온 코포레이션 | 리튬 이온 2 차 전지용 접착제, 리튬 이온 2 차 전지용 세퍼레이터, 및 리튬 이온 2 차 전지 |
KR20160030891A (ko) * | 2013-07-10 | 2016-03-21 | 제온 코포레이션 | 리튬 이온 2 차 전지용 접착제, 리튬 이온 2 차 전지용 세퍼레이터, 및 리튬 이온 2 차 전지 |
US10141557B2 (en) | 2013-07-10 | 2018-11-27 | Zeon Corporation | Adhesive for lithium ion secondary batteries, separator for lithium ion secondary batteries, and lithium ion secondary battery |
WO2015005151A1 (ja) * | 2013-07-10 | 2015-01-15 | 日本ゼオン株式会社 | リチウムイオン二次電池用多孔膜組成物、リチウムイオン二次電池用セパレータ、リチウムイオン二次電池用電極、及びリチウムイオン二次電池 |
US10283748B2 (en) | 2013-07-10 | 2019-05-07 | Zeon Corporation | Porous film composition for lithium ion secondary batteries, separator for lithium ion secondary batteries, electrode for lithium ion secondary batteries, and lithium ion secondary battery |
JPWO2015005145A1 (ja) * | 2013-07-10 | 2017-03-02 | 日本ゼオン株式会社 | リチウムイオン二次電池用接着剤、リチウムイオン二次電池用セパレータ、及びリチウムイオン二次電池 |
US9941518B2 (en) | 2013-10-09 | 2018-04-10 | Denka Company Limited | Cathode binder composition, cathode slurry, cathode, and lithium ion secondary battery |
JPWO2015053224A1 (ja) * | 2013-10-09 | 2017-03-09 | デンカ株式会社 | 正極用バインダー組成物、正極用スラリー、正極及びリチウムイオン二次電池 |
WO2015053224A1 (ja) * | 2013-10-09 | 2015-04-16 | 電気化学工業株式会社 | 正極用バインダー組成物、正極用スラリー、正極及びリチウムイオン二次電池 |
JP2015088253A (ja) * | 2013-10-28 | 2015-05-07 | 日本ゼオン株式会社 | リチウムイオン二次電池用接着剤、リチウムイオン二次電池用セパレータ及びリチウムイオン二次電池 |
US10374217B2 (en) | 2014-02-26 | 2019-08-06 | Jtekt Corporation | Apparatus and process for producing electricity storage material |
US9662806B2 (en) | 2014-02-26 | 2017-05-30 | Jtekt Corporation | Kneading device |
WO2015174036A1 (ja) * | 2014-05-14 | 2015-11-19 | 日本ゼオン株式会社 | 二次電池電極用バインダー組成物、二次電池電極用スラリー組成物、二次電池用電極およびその製造方法、並びに、二次電池 |
JPWO2015174036A1 (ja) * | 2014-05-14 | 2017-04-20 | 日本ゼオン株式会社 | 二次電池電極用バインダー組成物、二次電池電極用スラリー組成物、二次電池用電極およびその製造方法、並びに、二次電池 |
US11552297B2 (en) | 2014-06-04 | 2023-01-10 | Zeon Corporation | Binder composition for lithium ion secondary battery electrode-use, slurry composition for lithium ion secondary battery electrode-use, electrode for lithium ion secondary battery-use, and lithium ion secondary battery |
KR20170023788A (ko) * | 2014-06-27 | 2017-03-06 | 니폰 제온 가부시키가이샤 | 비수계 이차전지 기능층용 조성물, 비수계 이차전지용 기능층 및 비수계 이차전지 |
KR102422232B1 (ko) * | 2014-06-27 | 2022-07-15 | 니폰 제온 가부시키가이샤 | 비수계 이차전지 기능층용 조성물, 비수계 이차전지용 기능층 및 비수계 이차전지 |
JP2016024866A (ja) * | 2014-07-16 | 2016-02-08 | 日本ゼオン株式会社 | 非水系二次電池多孔膜用複合粒子、非水系二次電池用多孔膜、非水系二次電池用電池部材、および非水系二次電池 |
JPWO2016017066A1 (ja) * | 2014-07-30 | 2017-04-27 | 日本ゼオン株式会社 | 非水系二次電池機能層用組成物、非水系二次電池用機能層付き基材、非水系二次電池用積層体の製造方法および非水系二次電池 |
WO2016017066A1 (ja) * | 2014-07-30 | 2016-02-04 | 日本ゼオン株式会社 | 非水系二次電池機能層用組成物、非水系二次電池用機能層付き基材、非水系二次電池用積層体の製造方法および非水系二次電池 |
WO2016024383A1 (ja) * | 2014-08-11 | 2016-02-18 | 日本ゼオン株式会社 | 二次電池電極用バインダー組成物、二次電池電極用スラリー組成物、二次電池用電極および二次電池 |
KR102494518B1 (ko) * | 2014-08-28 | 2023-01-31 | 니폰 제온 가부시키가이샤 | 비수계 이차 전지용 적층체 및 비수계 이차 전지 부재의 제조 방법 |
JPWO2016031163A1 (ja) * | 2014-08-28 | 2017-06-08 | 日本ゼオン株式会社 | 非水系二次電池用積層体および非水系二次電池部材の製造方法 |
WO2016031163A1 (ja) * | 2014-08-28 | 2016-03-03 | 日本ゼオン株式会社 | 非水系二次電池用積層体および非水系二次電池部材の製造方法 |
KR20170044640A (ko) * | 2014-08-28 | 2017-04-25 | 니폰 제온 가부시키가이샤 | 비수계 이차 전지용 적층체 및 비수계 이차 전지 부재의 제조 방법 |
JPWO2016051674A1 (ja) * | 2014-09-29 | 2017-07-06 | 日本ゼオン株式会社 | 電気化学素子用接着剤組成物、電気化学素子用接着層、および電気化学素子 |
WO2016051674A1 (ja) * | 2014-09-29 | 2016-04-07 | 日本ゼオン株式会社 | 電気化学素子用接着剤組成物、電気化学素子用接着層、および電気化学素子 |
JP2016094581A (ja) * | 2014-11-17 | 2016-05-26 | パナック株式会社 | 固体高分子型燃料電池シール材用の樹脂組成物及び該樹脂組成物を用いた固体高分子型燃料電池用のシール材 |
JPWO2016110894A1 (ja) * | 2015-01-09 | 2017-10-19 | 日本ゼオン株式会社 | 非水系二次電池用セパレータおよびその製造方法、並びに、非水系二次電池 |
WO2016110894A1 (ja) * | 2015-01-09 | 2016-07-14 | 日本ゼオン株式会社 | 非水系二次電池用セパレータおよびその製造方法、並びに、非水系二次電池 |
WO2017094252A1 (ja) * | 2015-11-30 | 2017-06-08 | 日本ゼオン株式会社 | 非水系二次電池接着層用組成物、非水系二次電池用接着層、積層体および非水系二次電池 |
KR20220032117A (ko) * | 2016-03-10 | 2022-03-15 | 니폰 제온 가부시키가이샤 | 비수계 2차 전지 전극용 바인더, 비수계 2차 전지 전극용 슬러리, 비수계 2차 전지용 전극, 및 비수계 2차 전지 |
KR102455298B1 (ko) | 2016-03-10 | 2022-10-14 | 니폰 제온 가부시키가이샤 | 비수계 2차 전지 전극용 바인더, 비수계 2차 전지 전극용 슬러리, 비수계 2차 전지용 전극, 및 비수계 2차 전지 |
US10910651B2 (en) | 2016-03-10 | 2021-02-02 | Zeon Corporation | Binder for non-aqueous secondary battery electrode, slurry for non-aqueous secondary battery electrode, electrode for non-aqueous secondary battery, and non-aqueous secondary battery |
JPWO2017155059A1 (ja) * | 2016-03-10 | 2019-01-10 | 日本ゼオン株式会社 | 非水系二次電池電極用バインダー、非水系二次電池電極用スラリー、非水系二次電池用電極、および非水系二次電池 |
US20190097235A1 (en) * | 2016-03-10 | 2019-03-28 | Zeon Corporation | Binder for non-aqueous secondary battery electrode, slurry for non-aqueous secondary battery electrode, electrode for non-aqueous secondary battery, and non-aqueous secondary battery |
EP3429001A4 (en) * | 2016-03-10 | 2019-07-31 | Zeon Corporation | BLEACHERS FOR WATER-FREE SECONDARY BATTERY ELECTRODES, INSULATION FOR WATER-FREE SECONDARY BATTERY ELECTRODE, ELECTRODE FOR WATER-FREE SECONDARY BATTERIES AND WATER-FREE SECONDARY BATTERY |
US20200411867A1 (en) * | 2018-02-19 | 2020-12-31 | Zeon Corporation | Binder composition for non-aqueous secondary battery electrode, slurry composition for non-aqueous secondary battery electrode, electrode for non-aqueous secondary battery, and non-aqueous secondary battery |
WO2019159706A1 (ja) * | 2018-02-19 | 2019-08-22 | 日本ゼオン株式会社 | 非水系二次電池電極用バインダー組成物、非水系二次電池電極用スラリー組成物、非水系二次電池用電極および非水系二次電池 |
JP7327379B2 (ja) | 2018-02-19 | 2023-08-16 | 日本ゼオン株式会社 | 非水系二次電池電極用バインダー組成物、非水系二次電池電極用スラリー組成物、非水系二次電池用電極および非水系二次電池 |
US11996562B2 (en) * | 2018-02-19 | 2024-05-28 | Zeon Corporation | Binder composition for non-aqueous secondary battery electrode, slurry composition for non-aqueous secondary battery electrode, electrode for non-aqueous secondary battery, and non-aqueous secondary battery |
JPWO2019159706A1 (ja) * | 2018-02-19 | 2021-02-12 | 日本ゼオン株式会社 | 非水系二次電池電極用バインダー組成物、非水系二次電池電極用スラリー組成物、非水系二次電池用電極および非水系二次電池 |
JP2021046491A (ja) * | 2019-09-18 | 2021-03-25 | 株式会社日本触媒 | グラフト共重合体の製造方法 |
JP7395297B2 (ja) | 2019-09-18 | 2023-12-11 | 株式会社日本触媒 | グラフト共重合体の製造方法 |
WO2024124424A1 (zh) * | 2022-12-14 | 2024-06-20 | 江阴纳力新材料科技有限公司 | 导电粘结剂及其制备方法、集流体、电极和电池 |
CN116948128A (zh) * | 2023-09-20 | 2023-10-27 | 宁德时代新能源科技股份有限公司 | 接枝聚合物、制备方法、正极极片、二次电池和用电装置 |
CN116948128B (zh) * | 2023-09-20 | 2024-02-23 | 宁德时代新能源科技股份有限公司 | 接枝聚合物、制备方法、正极极片、二次电池和用电装置 |
Also Published As
Publication number | Publication date |
---|---|
KR20120038939A (ko) | 2012-04-24 |
JPWO2011001848A1 (ja) | 2012-12-13 |
CN102473917A (zh) | 2012-05-23 |
JP5621772B2 (ja) | 2014-11-12 |
CN102473917B (zh) | 2015-06-17 |
KR101539819B1 (ko) | 2015-07-27 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5621772B2 (ja) | 二次電池用電極及び二次電池 | |
JP5561276B2 (ja) | 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 | |
CN103636027B (zh) | 二次电池用多孔膜、制造方法及用途 | |
KR102165556B1 (ko) | 이차 전지용 세퍼레이터 | |
KR101819067B1 (ko) | 이차 전지용 정극 및 그 제조 방법, 슬러리 조성물, 그리고 이차 전지 | |
JP5549739B2 (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及び二次電池 | |
JP6222102B2 (ja) | リチウムイオン二次電池負極用スラリー組成物、リチウムイオン二次電池用負極及びその製造方法、並びにリチウムイオン二次電池 | |
JP5733219B2 (ja) | 二次電池用正極及び二次電池 | |
JP5598472B2 (ja) | 二次電池用多孔膜及び二次電池 | |
JP5534245B2 (ja) | 二次電池用正極及び二次電池 | |
JP6020209B2 (ja) | 二次電池負極用スラリー組成物の製造方法 | |
WO2010016476A1 (ja) | リチウムイオン二次電池用電極 | |
WO2011148970A1 (ja) | 二次電池用正極及び二次電池 | |
KR20120081983A (ko) | 이차 전지용 전극, 이차 전지 전극용 바인더 및 이차 전지 | |
WO2011078263A1 (ja) | 二次電池用電極及び二次電池 | |
JP5682557B2 (ja) | 二次電池用正極及び二次電池 | |
KR102654732B1 (ko) | 전기 화학 소자용 바인더 조성물, 전기 화학 소자 기능층용 슬러리 조성물, 전기 화학 소자 접착층용 슬러리 조성물, 및 복합막 | |
KR20230113728A (ko) | 전기 화학 소자용 전극 및 전기 화학 소자 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 201080029217.5 Country of ref document: CN |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 10794018 Country of ref document: EP Kind code of ref document: A1 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2011520870 Country of ref document: JP |
|
ENP | Entry into the national phase |
Ref document number: 20117030261 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: 10794018 Country of ref document: EP Kind code of ref document: A1 |