WO2015079549A1 - Pile rechargeable lithium-ion, son procédé de fabrication, et solution de liant pour pile rechargeable lithium-ion - Google Patents

Pile rechargeable lithium-ion, son procédé de fabrication, et solution de liant pour pile rechargeable lithium-ion Download PDF

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WO2015079549A1
WO2015079549A1 PCT/JP2013/082137 JP2013082137W WO2015079549A1 WO 2015079549 A1 WO2015079549 A1 WO 2015079549A1 JP 2013082137 W JP2013082137 W JP 2013082137W WO 2015079549 A1 WO2015079549 A1 WO 2015079549A1
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negative electrode
solvent
lithium ion
mixture layer
ion secondary
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PCT/JP2013/082137
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English (en)
Japanese (ja)
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尚貴 木村
栄二 關
ソクチョル 申
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株式会社日立製作所
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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 a lithium ion secondary battery and a method of manufacturing the same, and a binder solution for a lithium ion secondary battery.
  • an active material containing silicon As a negative electrode active material that can be expected to have a high energy density, an active material containing silicon (Si) is expected. However, since Si has a large volume change due to charge and discharge, the conductive network between the active material particles is broken, so there is a problem that the cycle deterioration is relatively large compared to other negative electrode active materials.
  • Patent Document 1 Japanese Patent Laid-Open No. 2004-349056
  • Patent Document 1 Japanese Patent Laid-Open No. 2004-349056
  • a negative electrode material for a lithium secondary battery which is characterized by comprising a substance core and a plurality of carbon fibers having one end bonded to the surface of the active substance core.
  • the conductivity between the active material cores is secured by the entanglement of innumerable carbon fibers, and the distance between the active material cores is reduced by repeating expansion and contraction of the negative electrode layer of the lithium secondary battery by charge and discharge. Even if it becomes large, the entanglement of carbon fiber is hardly affected, and as a result, it is said that the cycle characteristics are secured.
  • Patent Document 2 Japanese Patent Laid-Open No. 2009-15203 discloses a lithium secondary battery including an electrode body including a negative electrode having a negative electrode mixture layer, a positive electrode having a positive electrode mixture layer, and a separator.
  • the negative electrode mixture layer contains a negative electrode active material which is an element capable of alloying with Li or a compound having the element, and at least one binder selected from the group consisting of polyimide, polyamideimide and polyamide.
  • a lithium secondary battery is disclosed in which the separator is bonded to at least one of the negative electrode mixture layer of the negative electrode and the positive electrode mixture layer of the positive electrode. According to Patent Document 2, it is believed that it is possible to provide a lithium secondary battery that has a high capacity and suppresses the volume change of the negative electrode associated with charge and discharge.
  • the electrode of a lithium ion secondary battery was coated with a slurry for forming a mixture layer containing an active material, a binder (binder) and a solvent on a current collector (coating step) and dried Thereafter, the current collector and the dried mixture layer are compression molded.
  • the coatability of the slurry for forming the mixture layer on the current collector is poor, electrode failure (such as high resistance of the electrode due to peeling of the mixture layer from the current collector and coating unevenness) is caused. It causes the deterioration of battery characteristics. For this reason, a technique for improving the coatability of the slurry for forming the mixture layer is required.
  • Patent Document 3 Japanese Patent Application Laid-Open No. 11-260353
  • an organic solvent mainly composed of N-methyl-2-pyrrolidone is used as a lithium composite metal.
  • a method for producing a non-aqueous electrolyte secondary battery which comprises adding ethylene glycol monobutyl ether acetate to a slurry for a positive electrode prepared by dispersing an oxide, a conductive material and a binder.
  • Patent Document 3 the stability of the water content and viscosity of the slurry can be improved, and as a result, the variation of the coating amount on the current collector can be reduced.
  • the slurry for forming the mixture layer is filled in a coating dam having a coating guide, and the slurry is transferred to a transfer roll.
  • the properties (surface tension, viscosity, etc.) of the slurry a large amount of slurry will be accumulated on the coating guide side, the thickness of the edge of the mixture layer will increase, coating unevenness will occur, and electrode failure may occur. .
  • patent documents 1 and 2 attempt to suppress the volume change of the electrode and improve the cycle life, there is no disclosure of a technique for reducing the defect of the electrode.
  • attempts have been made to improve the stability of the moisture content and viscosity of the slurry and to reduce the variation in the coating amount on the current collector in Patent Document 3 described above, the cycle life is improved and combined.
  • a technique for reducing the increase in thickness of the agent layer edge surface There is no disclosure of a technique for reducing the increase in thickness of the agent layer edge surface.
  • the lithium ion secondary battery of the present invention is a lithium ion secondary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte solution containing a non-aqueous solvent and a support salt to achieve the above object
  • the negative electrode includes a negative electrode current collector and a negative electrode mixture layer
  • the negative electrode mixture layer includes a negative electrode active material, a binder, a first solvent, and a second solvent
  • the binder is at least one selected from the group consisting of polyimide, polyamideimide, and polyamide
  • the first solvent is N-methyl-2-pyrrolidone
  • the second solvent has a lower surface tension than the first solvent.
  • a lithium ion secondary which has excellent cycle life and reduces the increase in thickness of the edge surface of the negative electrode mixture layer to make the coated surface of the mixture layer uniform and reduces the electrode failure and the electrode resistance.
  • a battery can be provided.
  • FIG. 1 is an exploded perspective view schematically showing an example of a lithium ion secondary battery according to the present invention. It is a disassembled perspective view which shows the laminated electrode group 9 of FIG. 3 typically.
  • FIG. 1 is a schematic diagram which shows an example of the electrode preparation processes (a part of coating process) of a lithium ion secondary battery.
  • the slurry 12 for negative electrode mixture layer formation is filled in a coating dam 13 having a coating guide 11.
  • the negative electrode mixture layer forming slurry 12 is transferred to the transfer roll 14 and then transferred to a current collector (not shown).
  • FIG. 2A is a plan view schematically showing an example of a current collector having a negative electrode mixture layer formed according to the prior art
  • FIG. 2B is a schematic cross-sectional view of FIG. 2A.
  • the thickness of the edge surface tends to increase. It is considered that this is because a large amount of slurry is accumulated on the coating guide side depending on the properties of the slurry (surface tension, viscosity, etc.).
  • the thickness of the edge surface of the negative electrode mixture layer increases, a gap is formed between the current collector 23 provided on the upper side, and peeling of the negative electrode mixture layer 22 from the current collector 23 tends to occur easily. Further, the distance between the current collector 23 and the negative electrode mixture layer 22 is increased, and the electrode resistance is increased. As described above, when the thickness of the edge surface of the negative electrode mixture layer 22 is increased, an electrode failure is caused. Furthermore, when the thickness of the edge surface of the negative electrode mixture layer 22 is increased, there is a problem that the edge portion is caught when winding the current collector sheet, and the current collector sheet is cut.
  • the inventors of the present invention conducted intensive studies on the composition of the negative electrode mixture layer capable of enhancing the cycle life of the battery and reducing the increase in the thickness of the edge surface of the negative electrode mixture layer.
  • the negative electrode mixture layer contains at least one selected from the group consisting of polyimide, polyamideimide, and polyamide as a binder, N-methyl-2-pyrrolidone as a first solvent, and the second
  • the cycle life is excellent, and the increase in the thickness of the edge surface of the negative electrode mixture layer is reduced to coat the negative electrode mixture layer. It was clarified that the work surface can be made uniform, and electrode failure and electrode resistance can be reduced.
  • the present invention is based on the above findings.
  • Another aspect of the present invention is A method for producing a lithium ion secondary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolytic solution containing a non-aqueous solvent and a supporting salt
  • the step of manufacturing the negative electrode includes a step of preparing a negative electrode mixture layer forming slurry for preparing a negative electrode mixture layer forming slurry, and a coating step of applying the negative electrode mixture layer forming slurry on a negative electrode current collector A step of drying the negative electrode mixture layer forming slurry coated on the negative electrode current collector to obtain a negative electrode mixture layer, and a compression molding step of compression molding the negative electrode current collector and the negative electrode mixture layer
  • the negative electrode mixture layer includes a negative electrode active material, a binder, a first solvent, and a second solvent,
  • the binder is at least one selected from the group consisting of polyimide, polyamideimide, and polyamide
  • the first solvent is N-methyl-2-pyrrolidone
  • the second solvent is
  • another aspect of the present invention includes a binder, a first solvent, and a second solvent
  • the binder is at least one selected from the group consisting of polyimide, polyamideimide, and polyamide
  • the first solvent is N-methyl-2-pyrrolidone
  • the second solvent provides a binder solution for a lithium ion secondary battery characterized in that the surface tension is lower than that of the first solvent N-methyl-2-pyrrolidone.
  • a lamination type lamination cell is mentioned as a structure of a lithium ion secondary battery, it is not limited to this, Even if it is a winding structure, it is enclosed in a metal can. The same effect can be obtained even if it exists.
  • FIG. 3 is an exploded perspective view schematically showing an example of the lithium ion secondary battery according to the present invention.
  • the laminate electrode group 9 is sandwiched between the laminate films 8 and 10, and the creases of the laminate films 8 and 10 are heat sealed by welding (for example, 175 ° C. And the positive electrode terminal 1 and the negative electrode terminal 2 are penetrated in the electrically insulated state.
  • a heat-welding resin may be applied in advance or attached to the sealing portion of the terminal.
  • sealing is performed first by heat welding other than one side, and after injecting the electrolytic solution, the other side is sealed by heat welding while vacuum pressing.
  • the heat-welded portion is weaker in heat-welded strength than the other sides, and has the effect of the gas discharge valve.
  • a thin-walled portion or the like may be provided at another portion, and a portion having a gas discharge mechanism may be provided.
  • FIG. 4 is an exploded perspective view schematically showing the laminated electrode group 9 of FIG.
  • the laminated electrode group 9 is configured by laminating a plurality of plate-like positive electrodes 5 and a strip-like negative electrode 6 with a separator 7 interposed therebetween.
  • a positive electrode mixture layer is coated on both sides of a positive electrode current collector (for example, an aluminum foil having a thickness of 20 to 30 ⁇ m) in the positive electrode 5 constituting the laminated electrode group 9.
  • a negative electrode mixture layer is coated on both sides of a negative electrode current collector (for example, a copper foil having a thickness of 15 to 20 ⁇ m).
  • the positive electrode 5 has a positive electrode terminal 1 in which a part of the positive electrode is extended in a rectangular shape.
  • the negative electrode 6 has a negative electrode terminal 2 in which a part of the negative electrode is extended in a rectangular shape.
  • the positive electrode uncoated portion 3 and the negative electrode uncoated portion 4 on which the positive electrode mixture layer and the negative electrode mixture layer are not coated are formed on the positive electrode 5 and the negative electrode 6. That is, in the positive electrode uncoated portion 3 and the negative electrode uncoated portion 4, the current collector is exposed.
  • the positive electrode uncoated portion 3 and the negative electrode uncoated portion 4 are bundled and welded to the positive electrode terminal 1 and the negative electrode terminal 2 which electrically connect the inside and the outside of the battery.
  • the welding method is preferably resistance welding or ultrasonic welding.
  • the positive electrode terminal 1 and the negative electrode terminal 2 may be coated with a heat-welding resin in advance or attached to the sealing portion of the terminal.
  • the negative electrode of the lithium ion secondary battery according to the present invention includes the negative electrode current collector and the negative electrode mixture layer, and the negative electrode mixture layer contains the negative electrode active material, a binder, And a binder solution (binder solution) containing one solvent and a second solvent.
  • the negative electrode active material is not particularly limited, but it is preferable to use a negative electrode active material (Si-based negative electrode active material) containing silicon (Si).
  • a negative electrode active material Si-based negative electrode active material
  • the Si-based negative electrode active material can be expected to have a high energy density. Moreover, the volume change accompanying charging / discharging can be suppressed by using the binder mentioned later.
  • the Si-based negative electrode active material preferably includes a Si oxide represented by a chemical formula SiO x (0.5 ⁇ x ⁇ 1.5), or a Si alloy containing Si and a dissimilar metal element.
  • what mixed Si and graphite (C) may be included as a negative electrode active material.
  • the conductivity can be improved.
  • the content of Si is preferably 10 wt% or more of the negative electrode active material. If the silicon content is less than 10 wt%, sufficient energy density can not be obtained.
  • tin (Sn) -based negative electrode active materials including oxides of Sn or Sn alloys containing Sn and different metal elements
  • carbon (C) -based negative electrode active materials graphite
  • Sn-based negative electrode active material is also a material which is not as large as the Si-based negative electrode active material but relatively large in expansion and contraction due to charge and discharge.
  • Binder As the binder, at least one selected from the group consisting of polyimide (PI), polyamide imide (PAI), and polyamide (PA) is used. Expansion and contraction of the negative electrode active material can be suppressed by using such a binder.
  • the said binding agent can also be used independently, what mixed these may be used. Furthermore, they may be mixed with other binders such as polyvinylidene fluoride (PVDF) and styrene butadiene rubber (SBR).
  • PVDF polyvinylidene fluoride
  • SBR styrene butadiene rubber
  • NMP N-methyl-2-pyrrolidone
  • a solvent having a lower surface tension than the first solvent (NMP) is used as the second solvent of the negative electrode mixture layer.
  • NMP first solvent
  • the wettability between the current collector foil and the slurry for forming the negative electrode mixture layer becomes high, and it is possible to prevent the slurry for forming the negative electrode mixture layer from accumulating a large amount on the coating guide side.
  • An increase in the thickness of the edge surface can be reduced to make the coated surface uniform, and electrode defects can be reduced.
  • the surface tension of the second solvent is preferably 20 mN / m or more and less than 41 mN / m, and such solvents include 2-butoxyethanol (surface tension: 27.4 mN / m) and butyl cellosolve (surface tension: 27.4 mN / m), N, N-dimethylacetamide (surface tension: 32 mN / m), diethylene glycol diethyl ether (surface tension: 25 mN / m).
  • the surface tension of NMP is 41 mN / m. The value of the surface tension is based on the JIS standard.
  • the second solvent can be selected by actually measuring the surface tension using known methods and comparing with NMP. It can also be selected based on the values described in known literature. In addition, since surface tension changes with temperature, it is preferable to compare the surface tension of a 2nd solvent and the surface tension of NMP in the same temperature, and to select a 2nd solvent.
  • ring method ring method, JIS K2241
  • Wilhelmy method plate method or vertical plate method
  • hanging drop method rug drop method
  • the second solvent preferably has a boiling point of 150 ° C. or more and 210 ° C. or less.
  • the boiling point of NMP is about 200 ° C., and if the boiling point of the second solvent is less than 150 ° C., the second solvent evaporates first in the slurry for forming the negative electrode mixture layer to form bubbles, and the slurry is It becomes the cause of coating unevenness.
  • the boiling point of the second solvent is more than 210 ° C., the drying temperature becomes high, which is not preferable from the viewpoint of cost.
  • the remaining solvent amount of the first solvent and the second solvent in the negative electrode mixture layer (the amount of solvent remaining in the negative electrode mixture layer after drying the negative electrode mixture layer-forming slurry) is 0. 1 ppm or more and 100 ppm or less.
  • the second solvent having low surface tension remains, the wettability between the electrolytic solution and the electrode (active material) is improved, and the resistance of the electrode is considered to be reduced.
  • the amount of residual solvent in the negative electrode mixture layer can be confirmed by component analysis of the negative electrode mixture layer by gas chromatography.
  • the positive electrode includes a positive electrode current collector and a positive electrode mixture layer, and the positive electrode mixture layer includes a positive electrode active material, a binder (binder) and a solvent.
  • the positive electrode mixture layer includes a positive electrode active material, a binder (binder) and a solvent.
  • LiCoO 2 , LiNiO 2 , and LiMn 2 O 4 are suitable.
  • the separator is not particularly limited as long as it is a material that blocks lithium ions by heat contraction.
  • polyolefin etc. are used.
  • the polyolefin is mainly characterized by containing at least one of polyethylene, polypropylene and the like, but it is also possible to contain a heat resistant resin such as polyamide, polyamideimide, polyimide, polysulfone, polyethersulfone, polyphenylsulfone, polyacrylonitrile and the like Good.
  • the inorganic filler layer may be coated on one side or both sides.
  • the inorganic filler layer is characterized by containing at least one of SiO 2 , Al 2 O 3 , montmorillonite, mica, ZnO, TiO 2 , BaTiO 3 , and ZrO 2 , but from the viewpoint of cost and performance, SiO 2 or Al 2 O 3 is most preferred.
  • the electrolyte contains a non-aqueous solvent and a support salt.
  • the non-aqueous solvent and the supporting salt include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ⁇ -butyrolactone, ⁇ -valerolactone, methyl acetate , Ethyl acetate, methyl propionate, tetrahydrofuran, 2-methyltetrahydrofuran, 1,2-dimethoxyethane, 1-ethoxy-2-methoxyethane, 3-methyltetrahydrofuran, 1,2-dioxane, 1,3-dioxane, 1 Examples include 4-dioxane, 1,3-dioxolane, 2-methyl-1,3-dioxolane, 4-methyl-1,3-dioxolane and the like.
  • the supporting salt mention may be made of LiPF 6, LiBF 4, LiClO 4 , LiN (C 2 F 5 SO 2) 2 and lithium salt. Besides these, it is possible to use a known electrolyte used in a battery, such as a solid electrolyte having conductivity of lithium ions, a gel electrolyte or a molten salt. At least one of the support salts may be dissolved in at least one of the non-aqueous solvents, and used as an electrolyte (organic electrolyte).
  • the step of manufacturing the negative electrode comprises (i) preparing a slurry for forming a negative electrode mixture layer and preparing a slurry for forming a negative electrode mixture layer; (B) applying the slurry for forming the negative electrode mixture layer on the current collector; (iii) drying the slurry for forming the negative electrode mixture layer applied to the negative electrode current collector to obtain the negative electrode mixture layer; And (iv) a compression molding step of compression molding the negative electrode current collector and the negative electrode mixture layer.
  • the steps (i) to (iv) will be described.
  • the content of the second solvent is preferably more than 5 wt% and 50 wt% or less of the total weight of the first solvent and the second solvent. If the content of the second solvent is 5 wt% or less, the effect of reducing the increase in the thickness of the edge surface of the negative electrode mixture layer can not be sufficiently obtained. On the other hand, if it is more than 50 wt%, the proportion of NMP decreases, and the binder can not be sufficiently dissolved.
  • the solid content ratio of the negative electrode mixture layer-forming slurry can be 70% or more and 90% or less.
  • solid content ratio is a value defined by the following (Formula 1).
  • Solid content ratio (%) weight of binder / (weight of binder + weight of solvent) ⁇ 100 (formula 1)
  • the conventional slurry for forming the negative electrode mixture layer has a solid content ratio of 50 to 60%, but the slurry for forming the negative electrode mixture layer of the present invention achieves a higher value than before while having good coatability. it can. This is because the surface tension of the second solvent according to the present invention is low, and uniform coating can be performed even at a solid content ratio higher than that of the prior art.
  • the viscosity of the negative electrode mixture layer-forming slurry is preferably 3000 mPa or more and 10000 mPa or less, or the viscosity at 600 rpm at 0.5 rpm. It is believed that as the viscosity increases, the surface tension increases and the thickness of the edge surface of the negative electrode mixture layer increases. Therefore, in order to reduce the increase in the thickness of the edge surface of the negative electrode mixture layer, it is preferable to set the viscosity in the above range.
  • the slurry for forming the mixture layer is filled in a coating dam having a coating guide, and the slurry is transferred to a transfer roll, and then transferred to a current collector.
  • a device capable of performing such coating for example, a desk-top comma coater can be used.
  • the coating amount of the slurry for forming the negative electrode mixture layer is such that the volume ratio of the positive electrode to the negative electrode is 1.0 when the coating amount of the positive electrode is 240 g / m 2 , on one side of the electrode current collector. 10 g / m 2 or more, it is preferable that the 100 g / m 2 or less.
  • the negative electrode current collector is not particularly limited, and, for example, one made of copper or stainless steel (SUS) can be preferably used.
  • SUS has a low specific gravity and high strength, and is effective in improving cycle life and the like, copper is preferable from the viewpoint of cost.
  • the above current collector and the slurry for forming a negative electrode mixture layer are charged into a drying furnace, and the slurry for forming a negative electrode mixture layer is dried to obtain a negative electrode mixture layer.
  • the drying temperature is preferably 80 ° C. or more and 120 ° C. or less as primary drying, and more preferably 90 ° C. or more and 100 ° C. or less. Moreover, it is preferable that they are 150 degreeC or more and 350 degrees C or less as secondary drying, and it is more preferable that they are 200 degreeC or more and 300 degrees C or less.
  • composition of the negative electrode mixture layer forming slurry in each example is shown in Table 1 described later.
  • content rate (wt%) of a 2nd solvent is a value with respect to the total weight of a 1st solvent and a said 2nd solvent.
  • acetylene black was prepared as a conductive material.
  • the weight ratio of the negative electrode active material, the binder, and the conductive material was 92: 5: 3.
  • a negative electrode active material, a binder, and a conductive material were added to prepare a slurry for forming a negative electrode mixture layer.
  • (2) Production of Negative Electrode The negative electrode 6 was produced by applying the above-mentioned slurry for forming a negative electrode mixture layer on a negative electrode current collector, drying and compression molding with a roll press. Copper foil was prepared for the negative electrode current collector.
  • the table-top comma coater (made by Sunk Metal Co., Ltd.) was used for coating. Drying was performed using a drying oven at 90 ° C. for about 1 minute (primary drying), and vacuum drying (secondary drying) was further performed at 300 ° C. for 1 hour. In compression molding, the electrode density is pressed so that the porosity of the electrode is about 20 to 40%, and the negative electrode containing the SiO active material is pressed to a density of 1.3 to 1.5 g / cm 3, and Si The negative electrode containing the alloy was pressed to have a density of 2.0 to 2.4 g / cm 3 .
  • the positive electrode 5 prepares an aluminum foil as a positive electrode current collector foil, and coats the aluminum foil with a slurry for forming a positive electrode mixture layer containing a positive electrode active material, a binder and a solvent. It was made by drying and compression molding. LiNi 1/3 Mn 1/3 Co 1/3 O 2 was used as a positive electrode active material, PVDF was used as a binder, and NMP was used as a solvent. Furthermore, a carbon material was added as a conductive material to the slurry for forming a positive electrode mixture layer. The weight ratio of the positive electrode active material, the binder and the conductive material was 90: 5: 5. The coating amount of the slurry for positive electrode mixture layer formation was 240 g / m 2 . The compression molding was performed such that the density of the positive electrode 5 was 2.8 g / cm 3 .
  • the positive electrode uncoated portion 3 and the negative electrode uncoated portion 4 were bundled, and ultrasonic welding was performed on the positive electrode terminal 1 and the negative electrode terminal 2 which electrically connect the inside and the outside of the battery.
  • the welding method used resistance welding.
  • a support salt LiPF 6 of 1M EC (ethylene carbonate): EMC (ethyl methyl carbonate) 1: was used dissolved in 3 vol% of the solvent.
  • EMC ethyl methyl carbonate
  • a lithium ion secondary battery of Comparative Example 1 was produced in the same manner as in Example 1 except that the second solvent was not added to the negative electrode mixture layer-forming slurry.
  • the composition of the slurry for forming a negative electrode mixture layer in Comparative Example 1 is also described in Table 1 described later.
  • Lithium Ion Secondary Battery of Reference Example 1 A lithium ion secondary battery of Reference Example 1 was produced in the same manner as Example 1, except that the Si-based negative electrode active material was not used as the negative electrode active material, and only graphite (C) was added.
  • the composition of the slurry for forming the negative electrode mixture layer in Reference Example 1 is also described in Table 1 described later.
  • Examples 1 to 28 As shown in Tables 3 and 4, in all of Examples 1 to 28 according to the present invention, there is no peeling of the negative electrode mixture layer from the negative electrode current collector, and the thickness difference in the width direction of the negative electrode mixture layer is It became 4 micrometers or less, and it turned out that the increase in the negative mix layer edge face is a thing low enough. Also, the electrode resistance was 75 m ⁇ or less. That is, in Examples 1 to 28, no electrode failure was found, and the electrode resistance could be reduced. The low resistance in Examples 1 to 28 is due to the fact that the thickness of the negative electrode is made uniform (the coated surface of the negative electrode mixture layer is made uniform) and the distance between the electrodes is reduced, and the remaining in the negative electrode mixture layer. It is considered that the low surface tension solvent (second solvent) improves the wettability of the electrolytic solution and the electrode.
  • the low surface tension solvent second solvent
  • Example 1 by comparing Examples 1 to 4 and Comparative Example 1, the addition effect of the second solvent can be understood. Further, by comparing Example 1 with Reference Example 2, it is understood that the effect can not be obtained when the binder is PVDF, and by comparing Example 1, 13, 14 with Reference Example 3, It can be seen that the effect can not be obtained when the content of the solvent of 2 is 5 wt%.
  • the cycle life is excellent, and the increase in the thickness of the edge surface of the negative electrode mixture layer is reduced to make the coated surface of the mixture layer uniform and reduce the electrode failure and the electrode resistance. It has been demonstrated that a lithium ion secondary battery can be provided.
  • Positive electrode terminal 2 Negative electrode terminal 3: Positive electrode uncoated part 4: Negative electrode uncoated part 5.
  • Positive electrode 6 Negative electrode 7: Separator 8: Laminated film (case side) 9: lamination Electrode group, 10: laminate film (lid side), 11: coating guide, 12: slurry for forming a negative electrode mixture layer, 13: coating dam, 14: transfer roll, 15: transferred slurry, 21, 23 Current collector, 22: negative electrode mixture.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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Abstract

　L'invention concerne une pile rechargeable lithium-ion ayant une durée de vie cyclique exceptionnelle, par laquelle toute augmentation d'épaisseur d'une face latérale d'une couche de liant d'électrode négative est limitée et la surface de revêtement de la couche de mélange d'électrode négative est rendue uniforme, des défauts d'électrode étant réduits au minimum. La présente invention porte sur une pile rechargeable lithium-ion pourvue d'une électrode positive, d'une électrode négative et d'un électrolyte non aqueux contenant un solvant non aqueux et un sel support, la pile rechargeable lithium-ion étant caractérisée en ce que: l'électrode négative contient un collecteur de courant d'électrode négative et une couche de mélange d'électrode négative; la couche de mélange d'électrode négative contient un matériau actif d'électrode négative, un liant, un premier solvant et un second solvant; le liant est au moins un liant choisi dans le groupe comprenant un polyimide, un polyamide-imide et un polyamide; le premier solvant est la N-méthyl-2-pyrrolidone; et le second solvant a une plus faible tension superficielle que le premier solvant.
PCT/JP2013/082137 2013-11-29 2013-11-29 Pile rechargeable lithium-ion, son procédé de fabrication, et solution de liant pour pile rechargeable lithium-ion WO2015079549A1 (fr)

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JP2018190703A (ja) * 2016-12-09 2018-11-29 ユニチカ株式会社 バインダ溶液および塗液ならびに蓄電素子電極の製造方法
CN110299570A (zh) * 2018-03-23 2019-10-01 株式会社东芝 二次电池、电池组、车辆及固定用电源
CN112018327A (zh) * 2020-09-21 2020-12-01 珠海冠宇电池股份有限公司 一种负极片及制备方法、电池
CN115394953A (zh) * 2022-09-02 2022-11-25 湖北亿纬动力有限公司 一种凹凸阵列厚电极及其制备方法与应用
CN115394953B (zh) * 2022-09-02 2024-06-11 湖北亿纬动力有限公司 一种凹凸阵列厚电极及其制备方法与应用

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WO2006135113A1 (fr) * 2005-06-17 2006-12-21 Sumitomo Metal Mining Co., Ltd. Liquide d'enduction destiné à former une pellicule de nickel, pellicule de nickel et procédé pour la produire
JP2013219016A (ja) * 2012-01-24 2013-10-24 Daikin Ind Ltd 結着剤、正極合剤及び負極合剤
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JP2018190703A (ja) * 2016-12-09 2018-11-29 ユニチカ株式会社 バインダ溶液および塗液ならびに蓄電素子電極の製造方法
JP7116461B2 (ja) 2016-12-09 2022-08-10 ユニチカ株式会社 バインダ溶液および塗液ならびに蓄電素子電極の製造方法
CN110299570A (zh) * 2018-03-23 2019-10-01 株式会社东芝 二次电池、电池组、车辆及固定用电源
CN112018327A (zh) * 2020-09-21 2020-12-01 珠海冠宇电池股份有限公司 一种负极片及制备方法、电池
CN115394953A (zh) * 2022-09-02 2022-11-25 湖北亿纬动力有限公司 一种凹凸阵列厚电极及其制备方法与应用
CN115394953B (zh) * 2022-09-02 2024-06-11 湖北亿纬动力有限公司 一种凹凸阵列厚电极及其制备方法与应用

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