WO2017038327A1 - Secondary cell - Google Patents

Secondary cell Download PDF

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Publication number
WO2017038327A1
WO2017038327A1 PCT/JP2016/072099 JP2016072099W WO2017038327A1 WO 2017038327 A1 WO2017038327 A1 WO 2017038327A1 JP 2016072099 W JP2016072099 W JP 2016072099W WO 2017038327 A1 WO2017038327 A1 WO 2017038327A1
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WIPO (PCT)
Prior art keywords
negative electrode
positive electrode
protective layer
inorganic filler
secondary battery
Prior art date
Application number
PCT/JP2016/072099
Other languages
French (fr)
Japanese (ja)
Inventor
稔之 有賀
拓郎 綱木
三木　健
佐々木　寛文
Original Assignee
日立オートモティブシステムズ株式会社
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Application filed by 日立オートモティブシステムズ株式会社 filed Critical 日立オートモティブシステムズ株式会社
Priority to JP2017537666A priority Critical patent/JP6586169B2/en
Publication of WO2017038327A1 publication Critical patent/WO2017038327A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • 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
    • H01M10/058—Construction or 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a secondary battery.
  • Patent Document 1 discloses that a protective layer made of organic particles and inorganic particles is provided on at least one electrode of a sealed battery, and the organic particles in the protective layer are melted when abnormal heat is generated. A technology that improves safety by providing a shutdown function that closes holes is published.
  • the present invention has been made in view of the above problems, and its purpose is to provide a protective layer between the positive electrode and the negative electrode even when the secondary battery falls into a high temperature state, so that the positive electrode and the negative electrode It is intended to provide a secondary battery that can avoid the secondary short circuit between them and improve safety.
  • the present invention includes a plurality of means for solving the above problems.
  • the secondary battery includes an electrode group in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween.
  • the melting point is higher than the melting point of the separator.
  • the negative electrode protective layer provided on the surface of the negative electrode mixture layer has an inorganic filler, a resin filler having a melting point higher than that of the separator, and a binder, abnormal heat generation above the melting point of the separator.
  • the resin filler of the protective layer softens and develops adhesive strength, binds the inorganic filler, and can suppress the outflow of the protective layer. Therefore, even if the separator shrinks due to heat, the protective layer can suppress a secondary short circuit between the positive electrode and the negative electrode. Therefore, a highly safe battery can be provided.
  • the external appearance perspective view of a square secondary battery The disassembled perspective view of a square secondary battery.
  • the perspective view of a winding group The figure explaining the structure of a positive electrode.
  • the figure explaining the structure of a negative electrode Sectional drawing of the winding group in a present Example.
  • the cross-sectional image figure which shows an example of a negative electrode protective layer The cross-sectional image figure which shows the other example of a negative electrode protective layer.
  • the present invention provides an inorganic filler and a resin filler that have ionic conductivity on the negative electrode active material layer and avoid direct contact between the positive electrode uncoated portion and the negative electrode coated portion due to separator contraction when abnormal heat is generated due to an internal short circuit or the like.
  • the present invention relates to a sealed secondary battery including a layer made of
  • the present invention is applied to a prismatic lithium ion secondary battery having a flat wound electrode group.
  • the present invention is limited to the configurations of these examples.
  • the present invention can also be applied to secondary batteries having other types of electrode groups such as a stacked type in which a plurality of positive electrodes and negative electrodes are alternately stacked.
  • FIG. 1 is an external perspective view of a prismatic secondary battery
  • FIG. 2 is an exploded perspective view of the prismatic secondary battery.
  • the prismatic secondary battery 100 includes a battery can 1 and a battery lid 6.
  • the battery can 1 has a side surface and a bottom surface 1d having a pair of opposed wide side surfaces 1b having a relatively large area and a pair of opposed narrow side surfaces 1c having a relatively small area, and an opening 1a above the side surface 1d.
  • the wound group 3 is accommodated in the battery can 1, and the opening 1 a of the battery can 1 is sealed by the battery lid 6.
  • the battery lid 6 is a substantially rectangular flat plate that closes the opening 1 a and is welded to the battery can 1 to form a battery container in cooperation with the battery can 1.
  • the battery lid 6 is provided with a positive external terminal 14 and a negative external terminal 12.
  • the wound group 3 is charged through the positive external terminal 14 and the negative external terminal 12, and power is supplied to the external load.
  • the battery cover 6 is integrally provided with a gas discharge valve 10, and when the pressure in the battery container rises to a preset value or more, the gas discharge valve 10 is opened and gas is discharged from the inside, so that the inside of the battery container The pressure of is reduced. Thereby, the safety of the prismatic secondary battery 100 is ensured.
  • the wound group 3 is accommodated in an insulating protective film 2. Since the wound group 3 is wound in a flat shape, the wound group 3 has a pair of curved surface portions facing each other and having a semicircular cross section, and a flat surface portion formed continuously between the pair of curved surface portions. ing.
  • the winding group 3 is inserted into the battery can 1 from one curved surface portion side so that the winding axis direction is along the lateral width direction of the battery can 1, and the other curved surface portion side is disposed on the opening 1a side.
  • the positive electrode metal foil exposed portion 34 b of the winding group 3 is electrically connected to the positive electrode external terminal 14 provided on the battery lid 6 via the positive electrode current collector plate 44. Further, the negative electrode metal foil exposed portion 32 b of the wound group 3 is electrically connected to the negative electrode external terminal 12 provided on the battery lid 6 via the negative electrode current collector plate 24. Thereby, electric power is supplied from the winding group 3 to the external load via the positive electrode current collecting plate 44 and the negative electrode current collecting plate 24, and externally supplied to the wound group 3 via the positive electrode current collecting plate 44 and the negative electrode current collecting plate 24. The generated power is supplied and charged.
  • a gasket 5 and an insulating plate 7 are provided on the battery lid 6. It has been.
  • the material for forming the positive electrode external terminal 14 and the positive electrode current collector plate 44 include an aluminum alloy
  • examples of the material for forming the negative electrode external terminal 12 and the negative electrode current collector plate 24 include a copper alloy.
  • the material for forming the insulating plate 7 and the gasket 5 include resin materials having insulating properties such as polybutylene terephthalate, polyphenylene sulfide, and perfluoroalkoxy fluororesin.
  • the battery lid 6 is provided with a liquid injection port 9 for injecting the electrolytic solution into the battery container.
  • the liquid injection port 9 is injected by the liquid injection plug 11 after the electrolytic solution is injected into the battery container. Sealed.
  • the liquid injection plug 11 is joined to the battery lid 6 by laser welding to seal the liquid injection port 9 and seal the rectangular secondary battery 100.
  • a nonaqueous electrolytic solution in which a lithium salt such as lithium hexafluorophosphate (LiPF 6 ) is dissolved in an organic carbonate-based organic solvent such as ethylene carbonate is used as the electrolytic solution injected into the battery container. Can do.
  • the positive electrode connecting portion 14 a and the negative electrode connecting portion 12 a have a cylindrical shape that protrudes from the lower surface of the positive electrode external terminal 14 and the negative electrode external terminal 12 and can be inserted into the positive electrode side through hole 46 and the negative electrode side through hole 26 of the battery lid 6. Have.
  • the positive electrode connecting portion 14 a and the negative electrode connecting portion 12 a penetrate the battery lid 6 and are more inside the battery can 1 than the positive electrode current collector plate 44, the positive electrode current collector plate base 41 of the negative electrode current collector plate 24, and the negative electrode current collector plate base 21.
  • the positive electrode external terminal 14, the negative electrode external terminal 12, the positive electrode current collector plate 44, and the negative electrode current collector plate 24 are integrally fixed to the battery lid 6.
  • a gasket 5 is interposed between the positive electrode external terminal 14 and the negative electrode external terminal 12 and the battery cover 6, and an insulating plate is interposed between the positive electrode current collector plate 44, the negative electrode current collector plate 24 and the battery cover 6. 7 is interposed.
  • the positive electrode current collector plate 44 and the negative electrode current collector plate 24 are a rectangular plate-shaped positive electrode current collector plate base 41, a negative electrode current collector plate base 21, and a positive electrode current collector plate base 41 that are arranged to face the lower surface of the battery lid 6.
  • the negative electrode current collector plate base 21 is bent at the side end and extends toward the bottom surface along the wide surface of the battery can 1, and the positive electrode metal foil exposed portion 34 b and the negative electrode metal foil exposed portion of the wound group 3. It has the positive electrode side connection end part 42 and the negative electrode side connection end part 22 which are connected in the state which overlapped facing 32b.
  • the positive electrode current collector plate base 41 and the negative electrode current collector plate base 21 are respectively formed with a positive electrode side opening hole 43 and a negative electrode side opening hole 23 through which the positive electrode connection part 14a and the negative electrode connection part 12a are inserted.
  • FIG. 3 is an exploded perspective view showing a state in which a part of the wound group is developed.
  • the winding group 3 is configured by winding the negative electrode 32 and the positive electrode 34 in a flat shape with separators 33 and 35 interposed therebetween.
  • the outermost electrode is the negative electrode 32, and the separators 33 and 35 are wound outside thereof.
  • the separators 33 and 35 have a role of insulating between the positive electrode 34 and the negative electrode 32.
  • the separators 33 and 35 are provided with a plurality of fine holes through which the electrolytic solution can pass.
  • the negative electrode mixture layer 32a of the negative electrode 32 (see FIG. 5B) is larger in the width direction than the positive electrode mixture layer 34a of the positive electrode 34, and the positive electrode mixture layer 34a is always the negative electrode mixture layer 32a. It is configured to be sandwiched between them.
  • the positive electrode metal foil exposed portion 34b and the negative electrode metal foil exposed portion 32b are respectively bundled at a plane portion and connected to the positive electrode current collector plate 44 and the negative electrode current collector plate 24 by welding or the like.
  • the separators 33 and 35 are wider than the negative electrode mixture layer 32a in the width direction, the separators 33 and 35 are wound at positions where the metal foil surface at the end is exposed at the positive metal foil exposed portion 34b and the negative metal foil exposed portion 32b. , It does not hinder bundled welding. Moreover, it is also possible to arrange
  • the shaft core for example, a material obtained by winding a resin sheet having higher bending rigidity than any of the positive electrode metal foil, the negative electrode metal foil, and the separators 33 and 35 can be used.
  • polyolefin separators are used as the separators 33 and 35.
  • a polyolefin multilayer separator made of polypropylene (melting point: about 130 ° C.) and polyethylene (melting point: about 100 ° C.) is used.
  • the configuration of the separator is not limited to the polyolefin-based multilayer separator, but may be a single-layer separator made of polypropylene or polyethylene or a heat-resistant separator made of aramid.
  • the heat resistant coating layer which consists of an inorganic filler in the at least single side
  • this inorganic filler the same inorganic filler as the negative electrode protective layer 32c can be used.
  • the desired place of the present invention is that the melting point of the resin filler mixed in the negative electrode protective layer 32c disposed in the negative electrode 32 described later is higher than that of the separator.
  • the separator also has a shutdown function from the viewpoint of improving safety.
  • FIG. 4A and 4B are diagrams for explaining the configuration of the positive electrode in this example.
  • FIG. 4A is a front view showing a part of the positive electrode, and
  • FIG. It is A sectional view.
  • the positive electrode 34 has a positive electrode mixture layer 34a in which a positive electrode mixture is applied to both surfaces of a positive electrode metal foil that is a positive electrode current collector, and a positive electrode mixture is provided at one end in the width direction of the positive electrode metal foil.
  • An exposed positive metal foil exposed portion 34b is provided.
  • the positive electrode metal foil exposed portion 34b is a region where the metal surface of the positive electrode metal foil is exposed, and is wound so as to be disposed at one position in the winding axis direction.
  • the positive electrode 34 10 parts by weight of flaky graphite as a conductive material and 10 parts by weight of PVDF as a binder are added to 100 parts by weight of lithium manganate (chemical formula LiMn 2 O 4 ) as a positive electrode active material. Then, NMP was added as a dispersion solvent and kneaded to prepare a slurry-like positive electrode mixture. This slurry-like positive electrode mixture was applied on both sides of an aluminum foil (positive metal foil) having a thickness of 20 ⁇ m, leaving a positive metal foil exposed portion 34b (positive electrode uncoated portion) as a welded portion. Then, the positive electrode 34 with a thickness of 90 ⁇ m of the positive electrode mixture layer 34a not including the aluminum foil was obtained through drying, pressing, and cutting processes.
  • LiMn 2 O 4 lithium manganate
  • NMP was added as a dispersion solvent and kneaded to prepare a slurry-like positive electrode mixture.
  • This slurry-like positive electrode mixture was applied on both
  • lithium manganate is used as the positive electrode active material
  • other lithium manganate having a spinel crystal structure or a lithium manganese composite oxide or layered in which a part is substituted or doped with a metal element A lithium cobalt oxide or lithium titanate having a crystal structure, or a lithium-metal composite oxide obtained by substituting or doping a part thereof with a metal element may be used.
  • PVDF was used as the binder in the positive electrode mixture, but polytetrafluoroethylene (PTFE), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene butadiene rubber, and polysulfide rubber.
  • PTFE polytetrafluoroethylene
  • Polymers such as nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride, chloroprene fluoride, and acrylic resins, and mixtures thereof can be used.
  • FIG. 5A and 5B are diagrams for explaining the configuration of the negative electrode.
  • FIG. 5A is a front view showing a part of the negative electrode
  • FIG. 5B is a cross-sectional view taken along line AA in FIG. FIG.
  • the negative electrode 32 is provided on the surface of a negative electrode mixture layer 32a provided by applying a negative electrode mixture containing a negative electrode active material on both surfaces of a negative electrode metal foil which is a negative electrode current collector, and the surface of the negative electrode mixture layer 32a. Negative electrode protective layer 32c. And the negative electrode metal foil exposure part 32b in which the negative mix is not apply
  • the negative electrode metal foil exposed portion 32b is a region where the metal surface of the negative electrode metal foil is exposed, and is wound so as to be disposed at the position on the other side in the winding axis direction.
  • styrene butadiene rubber 1 part by weight of styrene butadiene rubber (hereinafter referred to as SBR) is added as a binder to 100 parts by weight of graphite powder as a negative electrode active material, and carboxymethyl cellulose (CMC) as a thickener. Was added thereto, and H 2 O was added thereto as a dispersion solvent and kneaded to prepare a negative electrode mixture.
  • SBR styrene butadiene rubber
  • the negative electrode mixture was applied to both sides of a 10 ⁇ m thick copper foil (negative electrode metal foil) leaving the negative electrode metal foil exposed portion 32b (negative electrode uncoated portion) as a welded portion, dried and pressed, and then protected for negative electrode
  • the slurry of the layer 32c was apply
  • the negative electrode mixture is applied, dried and pressed, and then the slurry for the negative electrode protective layer 32c is applied onto the negative electrode mixture layer 32a.
  • the present invention is not limited to this.
  • the negative electrode 32 may be produced by pressing and cutting.
  • graphite is used as the negative electrode active material, but the present invention is not limited to this.
  • Carbonaceous materials, amorphous carbon, compounds such as Si and Sn (for example, SiO, TiSi 2 etc.), or composite materials thereof may be used, and the particle shape may be scale-like, spherical, fibrous, massive, etc. There is no particular limitation.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • polyethylene polystyrene
  • polybutadiene butyl rubber
  • nitrile rubber polysulfide Polymers such as rubber, nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride, chloroprene fluoride, and acrylic resins, and mixtures thereof can be used.
  • H 2 O is used as a dispersion solvent for the coated portion of the negative electrode, not limited thereto, it may be used such as polyvinylidene fluoride (NMP) solvent.
  • NMP polyvinylidene fluoride
  • FIG. 6 is a cross-sectional view of the wound group in the first embodiment.
  • the negative electrode 32 has a negative electrode mixture layer 32a facing the positive electrode mixture layer 34a and wider than the positive electrode mixture layer 34a.
  • the negative electrode protective layer 32c has a width that covers the negative electrode mixture layer 32a, and has a size that covers the negative electrode mixture layer 32a so that the negative electrode mixture layer 32a is not exposed particularly at a portion facing the positive electrode metal foil exposed portion 34b via the separator. Is a requirement.
  • the negative electrode protective layer 32c in the present embodiment will be described with reference to a cross-sectional image diagram of the negative electrode protective layer 32c in FIG. Note that the cross-sectional image diagram of FIG. 7 is a structure inspired by Example 1-2 described later.
  • the negative electrode protective layer 32c is a mixture of an inorganic filler 32c1 and a resin filler 32c2 having a melting point higher than that of the separator as a protective material, SBR as a binder 32c3, and CMC (not shown) as a thickener. And including. H 2 O is added to these mixtures as a dispersion solvent and kneaded to produce a slurry-like mixture, which is applied to the desired location, dried, and evaporated to a thickness of about 5 ⁇ m. A negative electrode protective layer 32c having the same was formed.
  • the case where SBR is included as the binder of the negative electrode protective layer 32c and CMC is included as the thickener is exemplified, but the present invention is not limited thereto, and PVDF or acrylic is used as the binder. NMP may be used as a solvent.
  • the inorganic filler 32c1 is, for example, at least iron oxide, silica (SiO 2 ), alumina (Al 2 O 3 ), boehmite (Al 2 O 3 hydrate), titanium oxide (TiO 2 ), or barium titanate (BaTiO 2 ). Have one.
  • boehmite was used for the inorganic filler 32c1, and a battery in which the presence or absence of the resin filler, the material, and the composition ratio were changed was manufactured and the effect was verified.
  • a nail penetration test was conducted in which the battery was completely penetrated with a SUS nail having a diameter of 3 mm. The set SOC was set in increments of 5%, and the highest SOC that did not lead to smoke or ignition in the nail penetration test was used as an effect index.
  • the mechanism of heat generation by the nail penetration test is not clear, but as an example of a hypothesis, the penetration portion by the nail penetration is not only indirect short circuit through the nail, but also by the electrode breakage by the nail, the positive electrode 34 It is considered that a part of the negative electrode 32 and a part of the negative electrode 32 are in contact and directly short-circuited. In general, the greater the area of the part that is directly short-circuited, and the higher the SOC, the greater the amount of heat generated during the short-circuit. These heat generations promote the shrinkage of the separators 33 and 35, and reduce the binding force of the binder (SBR) 32c3 constituting the negative electrode protective layer 32c.
  • SBR binder
  • the separators 33 and 35 are shrunk, and the binding force of the binding material 32c3 of the constituent material of the negative electrode protection layer 32c becomes insufficient, and the resin filler 32c2 of the negative electrode protection layer 32c is melted. If it flows out between the positive electrode 34 and the negative electrode 32, the positive electrode metal foil exposed portion 34b and the negative electrode mixture layer 32a come into contact with each other, a secondary short circuit occurs, and eventually, ignition and smoke are caused. Is considered.
  • the negative electrode protective layer 32c can maintain sufficient insulation, it is possible to avoid a short circuit due to contact between the positive electrode 34 and the negative electrode 32 due to nail penetration and to suppress heat generation. In addition, since the heat generation is higher in the high SOC state, the separators 33 and 35 are likely to shrink. However, if the insulating property of the negative electrode protective layer 32c is sufficient, the positive metal foil exposed portion 34b and the negative electrode 32 A secondary short circuit can be avoided and safety can be ensured.
  • the binder (SBR in this embodiment) 32c3 of the negative electrode protective layer 32c is: In the case of an abnormal heat generation state, the function as a binder is decreased by melting, but at the same time, the resin filler 32c2 is softened to exhibit tackiness and exhibit a function as a second adhesive. In addition, the movement of the inorganic filler 32c1 is suppressed, and at the same time, the pores are closed and the insulating properties are improved. Therefore, a secondary short circuit in which the positive electrode 34 and the negative electrode 32 are directly short-circuited can be avoided, and safety can be improved.
  • Table 1 shows examples and comparative examples in which the composition of the negative electrode protective layer 32c was studied and the effects thereof.
  • Comparative Example 1-1 shown in Table 1 was prepared without the negative electrode protective layer 32c shown in FIGS. 5 and 6, and Comparative Example 1-2 was a resin applied to the negative electrode protective layer 32c.
  • the filler 32c2 was not mixed and it was produced using only the inorganic filler 32c1 and the binder 32c3.
  • polyethylene (PE) having a melting point substantially equal to that of the separators 33 and 35 is used for the resin filler of the comparative example
  • polyphenylene sulfide (PPS) having a melting point higher than that of the separators 33 and 35 is used for the resin filler of the example.
  • the effect was confirmed using.
  • a spherical inorganic filler having an aspect ratio of 2 or less was used.
  • the measurement of the particle size was performed using the particle size distribution measuring apparatus by a laser diffraction / scattering method.
  • Comparative Examples 1-3 to 1-5 were equivalent or less, and no improvement effect was observed. This is because in Comparative Examples 1-3 to 1-5, the amount of the inorganic filler was substantially reduced by mixing the resin filler, and the resin filler and the binder were at the same temperature as the melting point of the separator. Therefore, the resin filler and the binder of the protective layer are melted at the same time as the separator, and the inorganic filler fixed by the resin filler and the binder becomes movable, and a part of the negative electrode protective layer 32c is formed. It is thought that it flowed out and became thin and was in a state where sufficient insulation was not obtained.
  • Examples 1-1 to 1-3 Although the inorganic filler 32c1 is substantially reduced by mixing the resin filler 32c2, the heat resistance temperature of the resin filler 32c2 is high, so that the insulating property can be maintained. In addition, the resin filler 32c2 is softened by heat generation and develops an adhesive force, binds the inorganic filler 32c1 with a certain binding force, and exhibits a function as a second binding material. This is thought to be due to the suppression of movement, resulting in increased insulation.
  • Example 1-2 the level (Example 1-2) in which the mixing ratio of the inorganic filler 32c1 and the resin filler 32c2 was 3: 1 was most effective. This is presumed that Example 1-2 was provided with a sufficient amount of the inorganic filler 32c1 capable of ensuring insulation and was suitable for serving as the second binder by the resin filler 32c2.
  • Example 2-1 was more effective and could ensure safety at a high SOC (95%).
  • the particle size of the resin filler 32c2 and the particle size of the inorganic filler 32c1 are made different from each other, so that particles of two types of particle sizes are mixed. This is thought to be due to an increase in insulation and improved insulation.
  • the particle size of the resin filler 32c2 smaller than the particle size of the inorganic filler 32c1, the number of contacts where the inorganic filler 32c1 and the resin filler 32c2 are in contact with each other can be increased.
  • the voids of the negative electrode protective layer 32c are formed by melting the resin filler 32c2. It was estimated that the insulation was further improved.
  • Example 3-1 when Example 3-1 was compared with Example 2-1, Example 3-1 was more effective, and safety at the maximum SOC (100%) could be ensured.
  • the particle shape of the resin filler 32c2 is spherical, whereas the particle shape of the inorganic filler 32c1 is a plate, as shown in the image diagram of FIG.
  • the plate-like inorganic filler 32c1 has an aspect ratio of 5 or more, and in the present embodiment, a filler having a ratio of 5 to 15 was used.
  • the measurement of the particle size was performed using the particle size distribution measuring apparatus by a laser diffraction / scattering method.
  • Table 2 shows the results of the nail penetration test when the material of the inorganic filler 32c1 was changed with respect to Example 3-1.
  • boehmite Al 2 O 3 hydrate
  • alumina Al 2 O 3
  • silica silica
  • TiO 2 titanium oxide in example 4-3
  • TiO 4-4 barium titanate
  • Table 3 shows the results of a nail penetration test when separators 33 and 35 in which inorganic filler (alumina) 32c1 is applied to separators 33 and 35 are used in Example 3-1.
  • the secondary battery was produced so that the coating layer of the separators 33 and 35 might be arrange
  • Example 5-1 had the same maximum SOC as Example 3-1 but the highest temperature reached. This is because the coated layers of the separators 33 and 35 generally have an effect of suppressing the thermal contraction of the separators 33 and 35, so that the contraction of the separators 33 and 35 around the nail is suppressed, and the break due to the nail is short-circuited. It is considered that the maximum temperature reached has decreased due to a decrease in. Therefore, higher safety can be expected by combining the coated separator with improved heat resistance and this example.
  • the protective layer 32c is mixed with the resin filler 32c2 having a melting point higher than that of the separators 33 and 35 and the binder 32c3 of the protective layer 32c.
  • the function as the binder is exhibited to suppress the movement of the inorganic filler 32c1. Accordingly, even if the separators 33 and 35 are shrunk, the secondary short circuit between the positive electrode 34 and the negative electrode 32 can be avoided by the protective layer 32c, and safety can be improved.
  • the protective layer 32c is formed by mixing the inorganic filler 32c1 and the resin filler 32c2 has been described.
  • at least a part of the inorganic filler 32c1 is made of a resin such as PPS constituting the resin filler 32c2.
  • a coated material or a resin in which the resin constituting the resin filler 32c2 is supported on the inorganic filler 32c1 may be used, and the effect of improving the safety can be obtained similarly.
  • the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed.
  • the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described.
  • a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment.

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  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
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  • Engineering & Computer Science (AREA)
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Abstract

Provided is a secondary cell in which a protective layer is interposed between a positive electrode and a negative electrode such that secondary shorts between the positive electrode and the negative electrode can be avoided even when the secondary cell is in a high temperature state, thereby improving safety. This secondary cell 100 has a negative electrode protective layer 32c provided on a surface of a negative electrode mixture layer 32a of a negative electrode 32, wherein the negative electrode protective layer 32c includes an inorganic filler 32c1, a resin filler 32c2, and a binding material 32c3. A resin having a higher melting point than separators 33, 35 and the binding material 32c3 is used as the resin filler 32c2. As a result, at times of abnormal heat generation, this resin filler 32c2 functions as a second binding material, thereby inhibiting movement of the inorganic filler 32c1. Consequently, even if the separators 33, 35 shrink, secondary shorts between a positive electrode 34 and the negative electrode 32 can be avoided, thereby improving safety.

Description

二次電池Secondary battery
　本発明は、二次電池に関する。 The present invention relates to a secondary battery.
　近年、電気自動車等の動力源として、正極電極と負極電極との間にセパレータを介在させ、これらを捲回して作製した捲回式の電極群を備えたエネルギー密度の高いリチウムイオン二次電池の開発が進められている。また、高エネルギー化の一方で、安全性の両立が要求されている。本技術分野の背景技術として、特許文献１には、密閉型電池の少なくとも一方の電極に、有機粒子と無機粒子からなる保護層を設けて、異常発熱時に保護層の有機粒子を溶融させて細孔を塞ぐシャットダウン機能を持たせることで、安全性を向上させる技術が掲載されている。 In recent years, as a power source of an electric vehicle or the like, a lithium ion secondary battery having a high energy density provided with a wound electrode group produced by winding a separator between a positive electrode and a negative electrode and winding them. Development is underway. In addition, while achieving higher energy, compatibility with safety is required. As a background art of this technical field, Patent Document 1 discloses that a protective layer made of organic particles and inorganic particles is provided on at least one electrode of a sealed battery, and the organic particles in the protective layer are melted when abnormal heat is generated. A technology that improves safety by providing a shutdown function that closes holes is published.
特開2010-225545号公報JP 2010-225545 A
　しかしながら、特許文献１の技術では、保護層に溶融温度が100～200℃の範囲である有機粒子を用いているので、例えば釘などの鋭利な金属による電池の貫通や圧壊などによる異物を介する内部短絡等によりシャットダウン温度以上の異常発熱状態に陥った場合に、保護層の有機粒子が溶融してシュリンク（収縮）する。正極電極と負極電極との間にはセパレータが介在されているが、セパレータにポリエチレンからなるシャットダウン機能を有するものを用いている場合には、セパレータも溶融してシュリンクする。したがって、正極電極と負極電極との間からセパレータと保護層の両方が流出して、正極電極と負極電極とが部分的に直接接触して二次短絡を引き起こす可能性がある。 However, in the technique of Patent Document 1, since organic particles having a melting temperature in the range of 100 to 200 ° C. are used for the protective layer, for example, the inside of the battery through a foreign object due to penetration or crushing of a battery by a sharp metal such as a nail. In the case of an abnormal heat generation state above the shutdown temperature due to a short circuit or the like, the organic particles in the protective layer melt and shrink (shrink). A separator is interposed between the positive electrode and the negative electrode, but when the separator having a shutdown function made of polyethylene is used, the separator is also melted and shrinks. Therefore, both the separator and the protective layer may flow out between the positive electrode and the negative electrode, and the positive electrode and the negative electrode may be in direct contact with each other to cause a secondary short circuit.
　本発明は、上記課題に鑑みてなされたものであり、その目的は、二次電池が高温状態に陥ったときにも正極と負極との間に保護層が介在されて、正極と負極との間の二次短絡を回避し、安全性を向上させることができる二次電池を提供することにある。 The present invention has been made in view of the above problems, and its purpose is to provide a protective layer between the positive electrode and the negative electrode even when the secondary battery falls into a high temperature state, so that the positive electrode and the negative electrode It is intended to provide a secondary battery that can avoid the secondary short circuit between them and improve safety.
　上記課題を解決するために、例えば特許請求の範囲に記載の構成を採用する。本発明は、上記課題を解決する手段を複数含んでいるが、その一例を挙げるならば、正極電極と負極電極とをセパレータを介して積層した電極群を有する二次電池であって、負極電極は、負極合剤層と該負極合剤層の表面に設けられた負極保護層を有し、該負極保護層は、無機フィラーと、樹脂フィラーと、結着材を有し、前記樹脂フィラーの融点は、前記セパレータの融点よりも高いことを特徴とする。 In order to solve the above problems, for example, the configuration described in the claims is adopted. The present invention includes a plurality of means for solving the above problems. To give one example, the secondary battery includes an electrode group in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween. Has a negative electrode mixture layer and a negative electrode protective layer provided on the surface of the negative electrode mixture layer, and the negative electrode protective layer has an inorganic filler, a resin filler, and a binder. The melting point is higher than the melting point of the separator.
　本発明によれば、負極合剤層の表面に設けられた負極保護層が、無機フィラーと、セパレータよりも融点の高い樹脂フィラーと、結着材とを有するので、セパレータの融点以上の異常発熱時に、保護層の樹脂フィラーが軟化して粘着力を発現し、無機フィラーを結着し、保護層の流出を抑制することができる。したがって、セパレータが熱によってシュリンクしても、保護層により正極電極と負極電極との間の２次短絡を抑制することができる。したがって、安全性の高い電池を提供することができる。なお、上記した以外の課題、構成及び効果は、以下の実施形態の説明により明らかにされる。 According to the present invention, since the negative electrode protective layer provided on the surface of the negative electrode mixture layer has an inorganic filler, a resin filler having a melting point higher than that of the separator, and a binder, abnormal heat generation above the melting point of the separator. Sometimes, the resin filler of the protective layer softens and develops adhesive strength, binds the inorganic filler, and can suppress the outflow of the protective layer. Therefore, even if the separator shrinks due to heat, the protective layer can suppress a secondary short circuit between the positive electrode and the negative electrode. Therefore, a highly safe battery can be provided. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.
角形二次電池の外観斜視図。The external appearance perspective view of a square secondary battery. 角形二次電池の分解斜視図。The disassembled perspective view of a square secondary battery. 捲回群の斜視図。The perspective view of a winding group. 正極電極の構成を説明する図。The figure explaining the structure of a positive electrode. 負極電極の構成を説明する図。The figure explaining the structure of a negative electrode. 本実施例における捲回群の断面図。Sectional drawing of the winding group in a present Example. 負極保護層の一例を示す断面イメージ図。The cross-sectional image figure which shows an example of a negative electrode protective layer. 負極保護層の他の例を示す断面イメージ図。The cross-sectional image figure which shows the other example of a negative electrode protective layer.
　本発明は、負極活物質層上にイオン導電性を有し、内部短絡等で異常発熱した際、セパレータ収縮による正極未塗工部と負極塗工部の直接接触を避ける、無機フィラーと樹脂フィラーからなる層を備えた密閉型の二次電池に関する。 The present invention provides an inorganic filler and a resin filler that have ionic conductivity on the negative electrode active material layer and avoid direct contact between the positive electrode uncoated portion and the negative electrode coated portion due to separator contraction when abnormal heat is generated due to an internal short circuit or the like. The present invention relates to a sealed secondary battery including a layer made of
　以下、本発明の実施例について、図面を用いて説明する。なお、以下の実施例では、扁平捲回式の電極群を有する角形のリチウムイオン二次電池に本発明を適用した場合について説明するが、本発明は、これらの実施例の構成に限定されるものではなく、例えば複数枚の正極電極と負極電極を交互に積層した積層式等、他の形式の電極群を有する二次電池にも適用することができる。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following examples, the case where the present invention is applied to a prismatic lithium ion secondary battery having a flat wound electrode group will be described. However, the present invention is limited to the configurations of these examples. For example, the present invention can also be applied to secondary batteries having other types of electrode groups such as a stacked type in which a plurality of positive electrodes and negative electrodes are alternately stacked.
［実施例１］
　図１は、角形二次電池の外観斜視図、図２は、角形二次電池の分解斜視図である。
　角形二次電池１００は、電池缶１および電池蓋６を備える。電池缶１は、相対的に面積の大きい一対の対向する幅広側面１ｂと相対的に面積の小さい一対の対向する幅狭側面１ｃとを有する側面と底面１ｄを有し、その上方に開口部１ａを有する。 [Example 1]
FIG. 1 is an external perspective view of a prismatic secondary battery, and FIG. 2 is an exploded perspective view of the prismatic secondary battery.
The prismatic secondary battery 100 includes a battery can 1 and a battery lid 6. The battery can 1 has a side surface and a bottom surface 1d having a pair of opposed wide side surfaces 1b having a relatively large area and a pair of opposed narrow side surfaces 1c having a relatively small area, and an opening 1a above the side surface 1d. Have
　電池缶１内には、捲回群３が収納され、電池缶１の開口部１ａが電池蓋６によって封止されている。電池蓋６は、開口部１ａを塞ぐ略矩形平板状であって、電池缶１に溶接されて、電池缶１との協働により電池容器を形成する。電池蓋６には、正極外部端子１４と、負極外部端子１２が設けられている。正極外部端子１４と負極外部端子１２を介して捲回群３に充電され、また外部負荷に電力が供給される。 The wound group 3 is accommodated in the battery can 1, and the opening 1 a of the battery can 1 is sealed by the battery lid 6. The battery lid 6 is a substantially rectangular flat plate that closes the opening 1 a and is welded to the battery can 1 to form a battery container in cooperation with the battery can 1. The battery lid 6 is provided with a positive external terminal 14 and a negative external terminal 12. The wound group 3 is charged through the positive external terminal 14 and the negative external terminal 12, and power is supplied to the external load.
　電池蓋６には、ガス排出弁１０が一体的に設けられ、電池容器内の圧力が予め設定された値以上まで上昇すると、ガス排出弁１０が開いて内部からガスが排出され、電池容器内の圧力が低減される。これによって、角形二次電池１００の安全性が確保される。 The battery cover 6 is integrally provided with a gas discharge valve 10, and when the pressure in the battery container rises to a preset value or more, the gas discharge valve 10 is opened and gas is discharged from the inside, so that the inside of the battery container The pressure of is reduced. Thereby, the safety of the prismatic secondary battery 100 is ensured.
　電池缶１内には、捲回群３が絶縁保護フィルム２に包まれた状態で収容されている。捲回群３は、扁平形状に捲回されているため、断面半円形状の互いに対向する一対の湾曲面部と、これら一対の湾曲面部の間に連続して形成される平坦面部とを有している。捲回群３は、捲回軸方向が電池缶１の横幅方向に沿うように、一方の湾曲面部側から電池缶１内に挿入され、他方の湾曲面部側が開口部１ａ側に配置される。 In the battery can 1, the wound group 3 is accommodated in an insulating protective film 2. Since the wound group 3 is wound in a flat shape, the wound group 3 has a pair of curved surface portions facing each other and having a semicircular cross section, and a flat surface portion formed continuously between the pair of curved surface portions. ing. The winding group 3 is inserted into the battery can 1 from one curved surface portion side so that the winding axis direction is along the lateral width direction of the battery can 1, and the other curved surface portion side is disposed on the opening 1a side.
　捲回群３の正極金属箔露出部３４ｂは、正極集電板４４を介して電池蓋６に設けられた正極外部端子１４と電気的に接続されている。また、捲回群３の負極金属箔露出部３２ｂは、負極集電板２４を介して電池蓋６に設けられた負極外部端子１２と電気的に接続されている。これにより、正極集電板４４および負極集電板２４を介して捲回群３から外部負荷へ電力が供給され、正極集電板４４および負極集電板２４を介して捲回群３へ外部発電電力が供給され充電される。 The positive electrode metal foil exposed portion 34 b of the winding group 3 is electrically connected to the positive electrode external terminal 14 provided on the battery lid 6 via the positive electrode current collector plate 44. Further, the negative electrode metal foil exposed portion 32 b of the wound group 3 is electrically connected to the negative electrode external terminal 12 provided on the battery lid 6 via the negative electrode current collector plate 24. Thereby, electric power is supplied from the winding group 3 to the external load via the positive electrode current collecting plate 44 and the negative electrode current collecting plate 24, and externally supplied to the wound group 3 via the positive electrode current collecting plate 44 and the negative electrode current collecting plate 24. The generated power is supplied and charged.
　正極集電板４４と負極集電板２４、及び、正極外部端子１４と負極外部端子１２を、それぞれ電池蓋６から電気的に絶縁するために、ガスケット５および絶縁板７が電池蓋６に設けられている。正極外部端子１４および正極集電板４４の形成素材としては、例えばアルミニウム合金が挙げられ、負極外部端子１２および負極集電板２４の形成素材としては、例えば銅合金が挙げられる。また、絶縁板７およびガスケット５の形成素材としては、例えばポリブチレンテレフタレートやポリフェニレンサルファイド、ペルフルオロアルコキシフッ素樹脂等の絶縁性を有する樹脂材が挙げられる。 In order to electrically insulate the positive electrode current collector plate 44 and the negative electrode current collector plate 24, and the positive electrode external terminal 14 and the negative electrode external terminal 12 from the battery lid 6, a gasket 5 and an insulating plate 7 are provided on the battery lid 6. It has been. Examples of the material for forming the positive electrode external terminal 14 and the positive electrode current collector plate 44 include an aluminum alloy, and examples of the material for forming the negative electrode external terminal 12 and the negative electrode current collector plate 24 include a copper alloy. Examples of the material for forming the insulating plate 7 and the gasket 5 include resin materials having insulating properties such as polybutylene terephthalate, polyphenylene sulfide, and perfluoroalkoxy fluororesin.
　電池蓋６には、電池容器内に電解液を注入するための注液口９が穿設されており、この注液口９は、電解液を電池容器内に注入した後に注液栓１１によって封止される。注液栓１１は、レーザ溶接により電池蓋６に接合されて注液口９を封止し、角形二次電池１００を密閉する。電池容器内に注入される電解液としては、例えばエチレンカーボネート等の炭酸エステル系の有機溶媒に６フッ化リン酸リチウム（ＬｉＰＦ６）等のリチウム塩が溶解された非水電解液を適用することができる。 The battery lid 6 is provided with a liquid injection port 9 for injecting the electrolytic solution into the battery container. The liquid injection port 9 is injected by the liquid injection plug 11 after the electrolytic solution is injected into the battery container. Sealed. The liquid injection plug 11 is joined to the battery lid 6 by laser welding to seal the liquid injection port 9 and seal the rectangular secondary battery 100. For example, a nonaqueous electrolytic solution in which a lithium salt such as lithium hexafluorophosphate (LiPF 6 ) is dissolved in an organic carbonate-based organic solvent such as ethylene carbonate is used as the electrolytic solution injected into the battery container. Can do.
　正極接続部１４ａ、負極接続部１２ａは、正極外部端子１４、負極外部端子１２の下面からそれぞれ突出して先端が電池蓋６の正極側貫通孔４６、負極側貫通孔２６に挿入可能な円柱形状を有している。正極接続部１４ａ、負極接続部１２ａは、電池蓋６を貫通して正極集電板４４、負極集電板２４の正極集電板基部４１、負極集電板基部２１よりも電池缶１の内部側に突出しており、先端が“かしめ”られて、正極外部端子１４、負極外部端子１２と、正極集電板４４、負極集電板２４を電池蓋６に一体に固定している。正極外部端子１４、負極外部端子１２と電池蓋６との間には、ガスケット５が介在されており、正極集電板４４、負極集電板２４と電池蓋６との間には、絶縁板７が介在されている。 The positive electrode connecting portion 14 a and the negative electrode connecting portion 12 a have a cylindrical shape that protrudes from the lower surface of the positive electrode external terminal 14 and the negative electrode external terminal 12 and can be inserted into the positive electrode side through hole 46 and the negative electrode side through hole 26 of the battery lid 6. Have. The positive electrode connecting portion 14 a and the negative electrode connecting portion 12 a penetrate the battery lid 6 and are more inside the battery can 1 than the positive electrode current collector plate 44, the positive electrode current collector plate base 41 of the negative electrode current collector plate 24, and the negative electrode current collector plate base 21. The positive electrode external terminal 14, the negative electrode external terminal 12, the positive electrode current collector plate 44, and the negative electrode current collector plate 24 are integrally fixed to the battery lid 6. A gasket 5 is interposed between the positive electrode external terminal 14 and the negative electrode external terminal 12 and the battery cover 6, and an insulating plate is interposed between the positive electrode current collector plate 44, the negative electrode current collector plate 24 and the battery cover 6. 7 is interposed.
　正極集電板４４、負極集電板２４は、電池蓋６の下面に対向して配置される矩形板状の正極集電板基部４１、負極集電板基部２１と、正極集電板基部４１、負極集電板基部２１の側端で折曲されて、電池缶１の幅広面に沿って底面側に向かって延出し、捲回群３の正極金属箔露出部３４ｂ、負極金属箔露出部３２ｂに対向して重ね合わされた状態で接続される正極側接続端部４２、負極側接続端部２２を有している。正極集電板基部４１、負極集電板基部２１には、正極接続部１４ａ、負極接続部１２ａが挿通される正極側開口穴４３、負極側開口穴２３がそれぞれ形成されている。 The positive electrode current collector plate 44 and the negative electrode current collector plate 24 are a rectangular plate-shaped positive electrode current collector plate base 41, a negative electrode current collector plate base 21, and a positive electrode current collector plate base 41 that are arranged to face the lower surface of the battery lid 6. The negative electrode current collector plate base 21 is bent at the side end and extends toward the bottom surface along the wide surface of the battery can 1, and the positive electrode metal foil exposed portion 34 b and the negative electrode metal foil exposed portion of the wound group 3. It has the positive electrode side connection end part 42 and the negative electrode side connection end part 22 which are connected in the state which overlapped facing 32b. The positive electrode current collector plate base 41 and the negative electrode current collector plate base 21 are respectively formed with a positive electrode side opening hole 43 and a negative electrode side opening hole 23 through which the positive electrode connection part 14a and the negative electrode connection part 12a are inserted.
　図３は、捲回群の一部を展開した状態を示す分解斜視図である。
　捲回群３は、負極電極３２と正極電極３４を間にセパレータ３３、３５を介して扁平状に捲回することによって構成されている。捲回群３は、最外周の電極が負極電極３２であり、さらにその外側にセパレータ３３、３５が捲回される。セパレータ３３、３５は、正極電極３４と負極電極３２との間を絶縁する役割を有している。セパレータ３３、３５には、電解液が透過可能な複数の微細孔が設けられている。 FIG. 3 is an exploded perspective view showing a state in which a part of the wound group is developed.
The winding group 3 is configured by winding the negative electrode 32 and the positive electrode 34 in a flat shape with separators 33 and 35 interposed therebetween. In the winding group 3, the outermost electrode is the negative electrode 32, and the separators 33 and 35 are wound outside thereof. The separators 33 and 35 have a role of insulating between the positive electrode 34 and the negative electrode 32. The separators 33 and 35 are provided with a plurality of fine holes through which the electrolytic solution can pass.
　負極電極３２の負極合剤層３２ａ（図５（ｂ）を参照）は、正極電極３４の正極合剤層３４ａよりも幅方向に大きく、正極合剤層３４ａは、必ず負極合剤層３２ａの間に挟まれるように構成されている。正極金属箔露出部３４ｂと負極金属箔露出部３２ｂは、それぞれ平面部分で束ねられて溶接等により正極集電板４４と負極集電板２４に接続される。 The negative electrode mixture layer 32a of the negative electrode 32 (see FIG. 5B) is larger in the width direction than the positive electrode mixture layer 34a of the positive electrode 34, and the positive electrode mixture layer 34a is always the negative electrode mixture layer 32a. It is configured to be sandwiched between them. The positive electrode metal foil exposed portion 34b and the negative electrode metal foil exposed portion 32b are respectively bundled at a plane portion and connected to the positive electrode current collector plate 44 and the negative electrode current collector plate 24 by welding or the like.
　尚、セパレータ３３、３５は幅方向で負極合剤層３２ａよりも広いが、正極金属箔露出部３４ｂ、負極金属箔露出部３２ｂで端部の金属箔面が露出する位置に捲回されるため、束ねて溶接する場合の支障にはならない。また、必要に応じて、捲回群３の最内周に軸芯を配置することも可能である。軸芯としては例えば、正極金属箔、負極金属箔、セパレータ３３、３５のいずれよりも曲げ剛性の高い樹脂シートを捲回して構成したものを用いることができる。 Although the separators 33 and 35 are wider than the negative electrode mixture layer 32a in the width direction, the separators 33 and 35 are wound at positions where the metal foil surface at the end is exposed at the positive metal foil exposed portion 34b and the negative metal foil exposed portion 32b. , It does not hinder bundled welding. Moreover, it is also possible to arrange | position an axial center in the innermost periphery of the winding group 3 as needed. As the shaft core, for example, a material obtained by winding a resin sheet having higher bending rigidity than any of the positive electrode metal foil, the negative electrode metal foil, and the separators 33 and 35 can be used.
　本実施例では、セパレータ３３、３５には、ポリオレフィン系のセパレータを用いており、具体的には、ポリプロピレン（融点：130℃程度）とポリエチレン（融点：100℃程度）からなるポリオレフィン系多層セパレータを用いた。セパレータの構成は、ポリオレフィン系多層セパレータに限定されるものではなく、ポリプロピレンやポリエチレンからなる単層セパレータやアラミドからなる耐熱セパレータでもよい。 In this embodiment, polyolefin separators are used as the separators 33 and 35. Specifically, a polyolefin multilayer separator made of polypropylene (melting point: about 130 ° C.) and polyethylene (melting point: about 100 ° C.) is used. Using. The configuration of the separator is not limited to the polyolefin-based multilayer separator, but may be a single-layer separator made of polypropylene or polyethylene or a heat-resistant separator made of aramid.
　また、セパレータの少なくとも片面に無機フィラーからなる耐熱性の塗布層を有する構成としてもよい。この無機フィラーには、負極保護層３２ｃが有する無機フィラーと同じものを用いることができる。本発明の所望とする所は、後述する負極電極３２に配置されている、負極保護層３２ｃに混合されている樹脂フィラーの融点の方がセパレータよりも高いことが要件である。また、セパレータもシャットダウン機能を有しているほうが、安全性向上の観点からも好ましいと考える。 Moreover, it is good also as a structure which has the heat resistant coating layer which consists of an inorganic filler in the at least single side | surface of a separator. As this inorganic filler, the same inorganic filler as the negative electrode protective layer 32c can be used. The desired place of the present invention is that the melting point of the resin filler mixed in the negative electrode protective layer 32c disposed in the negative electrode 32 described later is higher than that of the separator. In addition, it is preferable that the separator also has a shutdown function from the viewpoint of improving safety.
　図４は、本実施例における正極電極の構成を説明する図であり、図４(ａ)は正極電極の一部を示す正面図、図４（ｂ）は、図４（ａ）のＡ－Ａ線断面図である。 4A and 4B are diagrams for explaining the configuration of the positive electrode in this example. FIG. 4A is a front view showing a part of the positive electrode, and FIG. It is A sectional view.
　正極電極３４は、正極集電体である正極金属箔の両面に正極合剤を塗布した正極合剤層３４ａを有し、正極金属箔の幅方向一方側の端部には、正極合剤を塗布しない正極金属箔露出部３４ｂが設けられている。正極金属箔露出部３４ｂは、正極金属箔の金属面が露出した領域であり、捲回軸方向の一方側の位置に配置されるように捲回される。 The positive electrode 34 has a positive electrode mixture layer 34a in which a positive electrode mixture is applied to both surfaces of a positive electrode metal foil that is a positive electrode current collector, and a positive electrode mixture is provided at one end in the width direction of the positive electrode metal foil. An exposed positive metal foil exposed portion 34b is provided. The positive electrode metal foil exposed portion 34b is a region where the metal surface of the positive electrode metal foil is exposed, and is wound so as to be disposed at one position in the winding axis direction.
　正極電極３４に関しては、正極活物質としてマンガン酸リチウム（化学式ＬｉＭｎ２Ｏ４）１００重量部に対し、導電材として１０重量部の鱗片状黒鉛と、結着材として１０重量部のＰＶＤＦとを添加し、これに分散溶媒としてＮＭＰを添加、混練してスラリ状の正極合剤を作製した。このスラリ状の正極合剤を厚さ２０μｍのアルミニウム箔（正極金属箔）の両面に溶接部である正極金属箔露出部３４ｂ（正極未塗工部）を残して塗布した。その後、乾燥、プレス、裁断工程を経て、アルミニウム箔を含まない正極合剤層３４ａの厚さ９０μｍの正極電極３４を得た。 As for the positive electrode 34, 10 parts by weight of flaky graphite as a conductive material and 10 parts by weight of PVDF as a binder are added to 100 parts by weight of lithium manganate (chemical formula LiMn 2 O 4 ) as a positive electrode active material. Then, NMP was added as a dispersion solvent and kneaded to prepare a slurry-like positive electrode mixture. This slurry-like positive electrode mixture was applied on both sides of an aluminum foil (positive metal foil) having a thickness of 20 μm, leaving a positive metal foil exposed portion 34b (positive electrode uncoated portion) as a welded portion. Then, the positive electrode 34 with a thickness of 90 μm of the positive electrode mixture layer 34a not including the aluminum foil was obtained through drying, pressing, and cutting processes.
　また、本実施例では、正極活物質にマンガン酸リチウムを用いる場合について例示したが、スピネル結晶構造を有する他のマンガン酸リチウムや一部を金属元素で置換又はドープしたリチウムマンガン複合酸化物や層状結晶構造を有すコバルト酸リチウムやチタン酸リチウムやこれらの一部を金属元素で置換またはドープしたリチウム-金属複合酸化物を用いるようにしてもよい。 Further, in this example, the case where lithium manganate is used as the positive electrode active material is exemplified, but other lithium manganate having a spinel crystal structure or a lithium manganese composite oxide or layered in which a part is substituted or doped with a metal element A lithium cobalt oxide or lithium titanate having a crystal structure, or a lithium-metal composite oxide obtained by substituting or doping a part thereof with a metal element may be used.
　また、本実施例では、正極合剤における結着材としてＰＶＤＦを用いる場合について例示したが、ポリテトラフルオロエチレン（ＰＴＦＥ）、ポリエチレン、ポリスチレン、ポリブタジエン、ブチルゴム、ニトリルゴム、スチレンブタジエンゴム、多硫化ゴム、ニトロセルロース、シアノエチルセルロース、各種ラテックス、アクリロニトリル、フッ化ビニル、フッ化ビニリデン、フッ化プロピレン、フッ化クロロプレン、アクリル系樹脂などの重合体およびこれらの混合体などを用いることができる。 In this example, PVDF was used as the binder in the positive electrode mixture, but polytetrafluoroethylene (PTFE), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene butadiene rubber, and polysulfide rubber. Polymers such as nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride, chloroprene fluoride, and acrylic resins, and mixtures thereof can be used.
　図５は、負極電極の構成を説明する図であり、図５（ａ）は、負極電極の一部を示す正面図、図５（ｂ）は、図５（ａ）のＡ－Ａ線断面図である。 5A and 5B are diagrams for explaining the configuration of the negative electrode. FIG. 5A is a front view showing a part of the negative electrode, and FIG. 5B is a cross-sectional view taken along line AA in FIG. FIG.
　負極電極３２は、負極集電体である負極金属箔の両面に負極活物質を含む負極合剤を塗工して設けられた負極合剤層３２ａと、負極合剤層３２ａの表面に設けられた負極保護層３２ｃとを有している。そして、負極金属箔の幅方向他方側の端部には、負極合剤が塗布されていない負極金属箔露出部３２ｂが形成されている。負極金属箔露出部３２ｂは、負極金属箔の金属面が露出した領域であり、捲回軸方向の他方側の位置に配置されるように捲回される。 The negative electrode 32 is provided on the surface of a negative electrode mixture layer 32a provided by applying a negative electrode mixture containing a negative electrode active material on both surfaces of a negative electrode metal foil which is a negative electrode current collector, and the surface of the negative electrode mixture layer 32a. Negative electrode protective layer 32c. And the negative electrode metal foil exposure part 32b in which the negative mix is not apply | coated is formed in the edge part of the width direction other side of negative electrode metal foil. The negative electrode metal foil exposed portion 32b is a region where the metal surface of the negative electrode metal foil is exposed, and is wound so as to be disposed at the position on the other side in the winding axis direction.
　負極電極３２に関しては、負極活物質として黒鉛粉末１００重量部に対して、結着材として１重量部のスチレンブタジエンゴム（以下、ＳＢＲという。）を添加し、増粘剤としてカルボキシメチルセルロース（ＣＭＣ）を添加し、これに分散溶媒としてＨ２Ｏを添加し、混練して負極合剤を作製した。この負極合剤を厚さ１０μｍの銅箔（負極金属箔）の両面に溶接部である負極金属箔露出部３２ｂ（負極未塗工部）を残して塗布し、乾燥、プレスした後、負極保護層３２ｃのスラリを負極合剤層３２ａ上に塗布し、裁断工程を経て、銅箔を含まない負極活物質塗布部の厚さ７０μｍの負極電極３２を得た。 Regarding the negative electrode 32, 1 part by weight of styrene butadiene rubber (hereinafter referred to as SBR) is added as a binder to 100 parts by weight of graphite powder as a negative electrode active material, and carboxymethyl cellulose (CMC) as a thickener. Was added thereto, and H 2 O was added thereto as a dispersion solvent and kneaded to prepare a negative electrode mixture. The negative electrode mixture was applied to both sides of a 10 μm thick copper foil (negative electrode metal foil) leaving the negative electrode metal foil exposed portion 32b (negative electrode uncoated portion) as a welded portion, dried and pressed, and then protected for negative electrode The slurry of the layer 32c was apply | coated on the negative mix layer 32a, and the negative electrode 32 with a thickness of 70 micrometers of the negative electrode active material application part which does not contain copper foil was obtained through the cutting process.
　尚、本実施形態では、負極合剤を塗布し、乾燥、プレスした後に、負極保護層３２ｃのスラリを負極合剤層３２ａ上に塗布する工法を取ったが、これに限定されるわけではなく、例えば、負極合剤と同時に負極保護層３２ｃのスラリを塗布した後に、プレス、裁断して負極電極３２を作製してもよい。 In the present embodiment, the negative electrode mixture is applied, dried and pressed, and then the slurry for the negative electrode protective layer 32c is applied onto the negative electrode mixture layer 32a. However, the present invention is not limited to this. For example, after applying the slurry of the negative electrode protective layer 32c simultaneously with the negative electrode mixture, the negative electrode 32 may be produced by pressing and cutting.
　尚、本実施形態では、負極活物質に黒鉛を用いる場合について例示したが、これに限定されるものではなく、リチウムイオンを挿入、脱離可能な天然黒鉛や、人造の各種黒鉛材、コークスなどの炭素質材料や非晶質炭素やＳｉやＳｎなどの化合物（例えば、ＳｉＯ、ＴｉＳｉ２等）、またはそれの複合材料でもよく、その粒子形状においても、鱗片状、球状、繊維状、塊状等、特に制限されるものではない。 In this embodiment, the case where graphite is used as the negative electrode active material is exemplified, but the present invention is not limited to this. Natural graphite capable of inserting and removing lithium ions, various artificial graphite materials, coke, etc. Carbonaceous materials, amorphous carbon, compounds such as Si and Sn (for example, SiO, TiSi 2 etc.), or composite materials thereof may be used, and the particle shape may be scale-like, spherical, fibrous, massive, etc. There is no particular limitation.
　また、負極電極における塗工部の結着材としてＳＢＲを用いる場合について例示したが、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリテトラフルオロエチレン（ＰＴＦＥ）、ポリエチレン、ポリスチレン、ポリブタジエン、ブチルゴム、ニトリルゴム、多硫化ゴム、ニトロセルロース、シアノエチルセルロース、各種ラテックス、アクリロニトリル、フッ化ビニル、フッ化ビニリデン、フッ化プロピレン、フッ化クロロプレン、アクリル系樹脂などの重合体およびこれらの混合体などを用いることができる。また、負極電極における塗工部の分散溶媒としてＨ２Ｏを用いる場合について例示したが、これに限られたものではなく、例えばポリフッ化ビニリデン（ＮＭＰ）溶媒を用いてもよい。 Moreover, although illustrated about the case where SBR is used as a binder of the coating part in a negative electrode, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, polysulfide Polymers such as rubber, nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride, chloroprene fluoride, and acrylic resins, and mixtures thereof can be used. Further, while an example has been shown where H 2 O is used as a dispersion solvent for the coated portion of the negative electrode, not limited thereto, it may be used such as polyvinylidene fluoride (NMP) solvent.
　図６は、実施例１における捲回群の断面図である。
　負極電極３２は、正極合剤層３４ａと対向しかつ正極合剤層３４ａよりも幅広の負極合剤層３２ａを有している。負極保護層３２ｃは、負極合剤層３２ａを覆う幅とし、特に正極金属箔露出部３４ｂにセパレータを介して対向する部分において、負極合剤層３２ａが露出しないように、覆う大きさとなっていることを要件とする。 FIG. 6 is a cross-sectional view of the wound group in the first embodiment.
The negative electrode 32 has a negative electrode mixture layer 32a facing the positive electrode mixture layer 34a and wider than the positive electrode mixture layer 34a. The negative electrode protective layer 32c has a width that covers the negative electrode mixture layer 32a, and has a size that covers the negative electrode mixture layer 32a so that the negative electrode mixture layer 32a is not exposed particularly at a portion facing the positive electrode metal foil exposed portion 34b via the separator. Is a requirement.
　次に、本実施例における負極保護層３２ｃについて図７に負極保護層３２ｃの断面イメージ図を用いて説明する。尚、図７の断面イメージ図は、後述する実施例１－２をイメージした構造である。 Next, the negative electrode protective layer 32c in the present embodiment will be described with reference to a cross-sectional image diagram of the negative electrode protective layer 32c in FIG. Note that the cross-sectional image diagram of FIG. 7 is a structure inspired by Example 1-2 described later.
　負極保護層３２ｃは、保護材として、無機フィラー３２ｃ１とセパレータの融点よりも高い融点を持つ樹脂フィラー３２ｃ２との混合とし、更に結着材３２ｃ３としてＳＢＲと、増粘剤としてＣＭＣ（図示せず）と、を含む。これらの混合物に分散溶媒としてＨ２Ｏを添加、混練してスラリ状の合剤を作製し、目的の箇所に塗布し乾燥して、分散溶媒を蒸発させることで、およそ5μm程度の厚さを有する負極保護層３２ｃを形成した。尚、本実施例では、負極保護層３２ｃの結着材としてＳＢＲを含み、増粘剤としてＣＭＣを含む場合を例示したが、これに限定されるわけではなく、結着材にＰＶＤＦやアクリル系のバインダを用い、溶媒にＮＭＰを用いても良い。 The negative electrode protective layer 32c is a mixture of an inorganic filler 32c1 and a resin filler 32c2 having a melting point higher than that of the separator as a protective material, SBR as a binder 32c3, and CMC (not shown) as a thickener. And including. H 2 O is added to these mixtures as a dispersion solvent and kneaded to produce a slurry-like mixture, which is applied to the desired location, dried, and evaporated to a thickness of about 5 μm. A negative electrode protective layer 32c having the same was formed. In the present embodiment, the case where SBR is included as the binder of the negative electrode protective layer 32c and CMC is included as the thickener is exemplified, but the present invention is not limited thereto, and PVDF or acrylic is used as the binder. NMP may be used as a solvent.
　無機フィラー３２ｃ１は、例えば酸化鉄、シリカ（ＳｉＯ2）、アルミナ（Ａｌ2Ｏ3）、ベーマイト（Ａｌ2Ｏ3水和物）、酸化チタン（ＴｉＯ2）、チタン酸バリウム（ＢａＴｉＯ2）の少なくともいずれかを有する。本実施例では、無機フィラー３２ｃ１にベーマイトを用い、樹脂フィラーの有無や材質および組成比を変化させた電池を作製し効果の検証を行った。効果の検証として、通常使用される範囲外の過酷な内部短絡を模擬するために、φ３ｍｍのＳＵＳ製の釘で電池を全貫通させる釘刺し試験を実施した。尚、設定ＳＯＣは5％刻みとし、効果の指標には、釘刺し試験における発煙・発火に至らない最高ＳＯＣを用いた。 The inorganic filler 32c1 is, for example, at least iron oxide, silica (SiO 2 ), alumina (Al 2 O 3 ), boehmite (Al 2 O 3 hydrate), titanium oxide (TiO 2 ), or barium titanate (BaTiO 2 ). Have one. In this example, boehmite was used for the inorganic filler 32c1, and a battery in which the presence or absence of the resin filler, the material, and the composition ratio were changed was manufactured and the effect was verified. As a verification of the effect, in order to simulate a severe internal short-circuit outside the range normally used, a nail penetration test was conducted in which the battery was completely penetrated with a SUS nail having a diameter of 3 mm. The set SOC was set in increments of 5%, and the highest SOC that did not lead to smoke or ignition in the nail penetration test was used as an effect index.
　釘刺し試験による発熱のメカニズムについては、定かでは無いが、仮説の一例を挙げると、釘刺しによる貫通部は、釘を介しての間接短絡だけでなく、釘による電極の破断により、正極電極３４の一部と負極電極３２の一部とが接触して直接短絡していると思われる。一般的に直接短絡している部分の面積が多いほど、また、ＳＯＣが高いほど、短絡時の発熱量は多くなる。これらの発熱によりセパレータ３３、３５のシュリンクを助長し、かつ、負極保護層３２ｃの構成材料の結着材（ＳＢＲ）３２ｃ３の結着力を低下させる。 The mechanism of heat generation by the nail penetration test is not clear, but as an example of a hypothesis, the penetration portion by the nail penetration is not only indirect short circuit through the nail, but also by the electrode breakage by the nail, the positive electrode 34 It is considered that a part of the negative electrode 32 and a part of the negative electrode 32 are in contact and directly short-circuited. In general, the greater the area of the part that is directly short-circuited, and the higher the SOC, the greater the amount of heat generated during the short-circuit. These heat generations promote the shrinkage of the separators 33 and 35, and reduce the binding force of the binder (SBR) 32c3 constituting the negative electrode protective layer 32c.
　捲回群３の構造上、セパレータ３３、３５がシュリンクし、また負極保護層３２ｃの構成材料の結着材３２ｃ３の結着力が不十分になり、負極保護層３２ｃの樹脂フィラー３２ｃ２が溶融して正極電極３４と負極電極３２との間から流れ出てしまうと、正極金属箔露出部３４ｂと負極合剤層３２ａが接触することになり、二次短絡が発生し、終には発火・発煙に至ると考察している。 Due to the structure of the wound group 3, the separators 33 and 35 are shrunk, and the binding force of the binding material 32c3 of the constituent material of the negative electrode protection layer 32c becomes insufficient, and the resin filler 32c2 of the negative electrode protection layer 32c is melted. If it flows out between the positive electrode 34 and the negative electrode 32, the positive electrode metal foil exposed portion 34b and the negative electrode mixture layer 32a come into contact with each other, a secondary short circuit occurs, and eventually, ignition and smoke are caused. Is considered.
　ここで、負極保護層３２ｃが十分な絶縁性を保持できていれば、釘刺し破断による正極電極３４および負極電極３２の接触による短絡を回避し、発熱を抑制することが出来る。また、高いＳＯＣ状態では発熱がより多くなるので、セパレータ３３、３５がシュリンクしやすい状態となるが、負極保護層３２ｃの絶縁性が十分であれば、正極金属箔露出部３４ｂと負極電極３２の二次短絡を回避することができ、安全性を確保することができる。 Here, if the negative electrode protective layer 32c can maintain sufficient insulation, it is possible to avoid a short circuit due to contact between the positive electrode 34 and the negative electrode 32 due to nail penetration and to suppress heat generation. In addition, since the heat generation is higher in the high SOC state, the separators 33 and 35 are likely to shrink. However, if the insulating property of the negative electrode protective layer 32c is sufficient, the positive metal foil exposed portion 34b and the negative electrode 32 A secondary short circuit can be avoided and safety can be ensured.
　本発明が所望とするところは、異常発熱時に十分な絶縁性を確保することであり、図７を用いてメカニズムを説明すると、負極保護層３２ｃの結着材（本実施例ではＳＢＲ）３２ｃ３は、異常発熱状態になった場合、溶融して結着材としての機能が低下するが、それと同時に、樹脂フィラー３２ｃ２が軟化して粘着性を発現し、第二の接着剤としての機能を発揮し、無機フィラー３２ｃ１の動きを抑制すると同時に、細孔を塞ぎ絶縁性を向上する。したがって、正極電極３４と負極電極３２とが直接短絡する２次短絡を回避でき、安全性を向上させることができる。 What the present invention desires is to ensure sufficient insulation during abnormal heat generation. The mechanism will be described with reference to FIG. 7. The binder (SBR in this embodiment) 32c3 of the negative electrode protective layer 32c is: In the case of an abnormal heat generation state, the function as a binder is decreased by melting, but at the same time, the resin filler 32c2 is softened to exhibit tackiness and exhibit a function as a second adhesive. In addition, the movement of the inorganic filler 32c1 is suppressed, and at the same time, the pores are closed and the insulating properties are improved. Therefore, a secondary short circuit in which the positive electrode 34 and the negative electrode 32 are directly short-circuited can be avoided, and safety can be improved.
　表１は、負極保護層３２ｃの組成について検討を行った実施例及び比較例とその効果を示すものである。尚、効果比較のため、表１に示す比較例１-１は、図５および図６中の負極保護層３２ｃを配置しないものを作製し、比較例１-２は、負極保護層３２ｃに樹脂フィラー３２ｃ２を混合せず、無機フィラー３２ｃ１と結着材３２ｃ３のみを用いて作製した。また、比較例の樹脂フィラーには、セパレータ３３、３５の融点とほぼ同等のポリエチレン（ＰＥ）を用い、実施例の樹脂フィラーには、セパレータ３３、３５よりも高い融点をもつポリフェニレンサルファイド（ＰＰＳ）を用いてその効果を確認した。球状の無機フィラーは、アスペクト比が２以下のものを用いた。そして、粒径の測定は、レーザ回析・散乱法による粒度分布測定装置を用いて行った。 Table 1 shows examples and comparative examples in which the composition of the negative electrode protective layer 32c was studied and the effects thereof. For comparison of effects, Comparative Example 1-1 shown in Table 1 was prepared without the negative electrode protective layer 32c shown in FIGS. 5 and 6, and Comparative Example 1-2 was a resin applied to the negative electrode protective layer 32c. The filler 32c2 was not mixed and it was produced using only the inorganic filler 32c1 and the binder 32c3. In addition, polyethylene (PE) having a melting point substantially equal to that of the separators 33 and 35 is used for the resin filler of the comparative example, and polyphenylene sulfide (PPS) having a melting point higher than that of the separators 33 and 35 is used for the resin filler of the example. The effect was confirmed using. A spherical inorganic filler having an aspect ratio of 2 or less was used. And the measurement of the particle size was performed using the particle size distribution measuring apparatus by a laser diffraction / scattering method.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１の結果から、比較例１-１と比較例１-２を比較すると、比較例１-２の方がより高いＳＯＣまで発火・発煙に至らなかったので、負極保護層３２ｃを配置することによる安全性向上の効果が認められた。 From the results shown in Table 1, when Comparative Example 1-1 and Comparative Example 1-2 were compared, Comparative Example 1-2 did not reach ignition / smoke up to a higher SOC, so the negative electrode protective layer 32c was disposed. The safety improvement effect by was confirmed.
　次に、比較例１-２に対して、比較例１－３～１－５は、同等以下であり改善の効果は見られなかった。これは、比較例１－３～１－５は、樹脂フィラーを混合することで、実質的に無機フィラーの量が減少したことに加え、樹脂フィラーと結着材がセパレータの融点とほぼ同じ温度であるため、セパレータと同時に保護層の樹脂フィラーと結着材とが溶融し、樹脂フィラーと結着材によって固定されていた無機フィラーが移動可能になってしまい、負極保護層３２ｃの一部が流れ出て薄く租な状態となり、十分な絶縁性が得られない状態となったと考えられる。 Next, compared with Comparative Example 1-2, Comparative Examples 1-3 to 1-5 were equivalent or less, and no improvement effect was observed. This is because in Comparative Examples 1-3 to 1-5, the amount of the inorganic filler was substantially reduced by mixing the resin filler, and the resin filler and the binder were at the same temperature as the melting point of the separator. Therefore, the resin filler and the binder of the protective layer are melted at the same time as the separator, and the inorganic filler fixed by the resin filler and the binder becomes movable, and a part of the negative electrode protective layer 32c is formed. It is thought that it flowed out and became thin and was in a state where sufficient insulation was not obtained.
　次に、比較例１－２～１－５と実施例１－１～１－３を比較すると、実施例１－１～１－３はいずれも最高ＳＯＣの数値が上昇しており、安全性向上の効果がみられた。これは、実施例１－１～１－３は、樹脂フィラー３２ｃ２の混合により無機フィラー３２ｃ１は実質的に減少しているが、樹脂フィラー３２ｃ２の耐熱温度が高いため、絶縁性が保持できていることに加え、発熱により樹脂フィラー３２ｃ２が軟化して粘着力を発現し、ある程度の結着力で無機フィラー３２ｃ１を結着し、第二の結着材としての機能を発揮することで、無機フィラーの動きを抑制し、結果的に絶縁性が高まったためと考えられる。 Next, when Comparative Examples 1-2 to 1-5 and Examples 1-1 to 1-3 are compared, all of Examples 1-1 to 1-3 have increased maximum SOC values, and safety is improved. The improvement effect was seen. In Examples 1-1 to 1-3, although the inorganic filler 32c1 is substantially reduced by mixing the resin filler 32c2, the heat resistance temperature of the resin filler 32c2 is high, so that the insulating property can be maintained. In addition, the resin filler 32c2 is softened by heat generation and develops an adhesive force, binds the inorganic filler 32c1 with a certain binding force, and exhibits a function as a second binding material. This is thought to be due to the suppression of movement, resulting in increased insulation.
　実施例１－１～１－３を比較すると、無機フィラー３２ｃ１と樹脂フィラー３２ｃ２の混合比が３：１の水準（実施例１－２）が最も効果があった。これは、実施例１－２は、絶縁を確保できる十分な量の無機フィラー３２ｃ１が配置されており、かつ樹脂フィラー３２ｃ２による第二の結着材としての役割を担うに適量であったと推察される。 When Examples 1-1 to 1-3 were compared, the level (Example 1-2) in which the mixing ratio of the inorganic filler 32c1 and the resin filler 32c2 was 3: 1 was most effective. This is presumed that Example 1-2 was provided with a sufficient amount of the inorganic filler 32c1 capable of ensuring insulation and was suitable for serving as the second binder by the resin filler 32c2. The
　つぎに実施例２－１と実施例１－２を比較すると、実施例２－１はさらに効果があり、高いＳＯＣ（９５％）での安全性を確保することが出来た。これは、実施例２－１は、樹脂フィラー３２ｃ２の粒径と無機フィラー３２ｃ１の粒径を互いに異ならせて２種類の粒径の粒子を混合させており、これにより、負極保護層３２ｃの密度が高まり、絶縁性が向上したからと考えられる。そして、樹脂フィラー３２ｃ２の粒径を無機フィラー３２ｃ１の粒径よりも小さくすることで、無機フィラー３２ｃ１と樹脂フィラー３２ｃ２とが接する接点数を増加させることができ、異常発熱により樹脂フィラー３２ｃ２が第二の結着材としての機能を発揮したときに、無機フィラー３２ｃ１をより強固に結着して無機フィラー３２ｃ１の動きを抑制する効果に加えて、樹脂フィラー３２ｃ２の溶融により負極保護層３２ｃの空隙を埋め、さらに絶縁性が向上したと推察した。 Next, when Example 2-1 and Example 1-2 were compared, Example 2-1 was more effective and could ensure safety at a high SOC (95%). In Example 2-1, the particle size of the resin filler 32c2 and the particle size of the inorganic filler 32c1 are made different from each other, so that particles of two types of particle sizes are mixed. This is thought to be due to an increase in insulation and improved insulation. Then, by making the particle size of the resin filler 32c2 smaller than the particle size of the inorganic filler 32c1, the number of contacts where the inorganic filler 32c1 and the resin filler 32c2 are in contact with each other can be increased. In addition to the effect of suppressing the movement of the inorganic filler 32c1 by binding the inorganic filler 32c1 more firmly when functioning as a binder, the voids of the negative electrode protective layer 32c are formed by melting the resin filler 32c2. It was estimated that the insulation was further improved.
　つぎに、実施例３－１と実施例２－１を比較すると、実施例３－１の方がさらに効果があり、最高ＳＯＣ（１００％）での安全性を確保することが出来た。これは、実施例３－１は、図８にイメージ図を示すように、樹脂フィラー３２ｃ２の粒子形状が球状であるのに対して、無機フィラー３２ｃ１の粒子形状が板状のものを用いており、これにより、さらに接点数を増加させて無機フィラー３２ｃ１の動きを抑制し、安全性が高まったと推察した。板状の無機フィラー３２ｃ１は、アスペクト比が５以上であり、本実施例では、５以上１５以下のものを用いた。そして、粒径の測定は、レーザ回析・散乱法による粒度分布測定装置を用いて行った。 Next, when Example 3-1 was compared with Example 2-1, Example 3-1 was more effective, and safety at the maximum SOC (100%) could be ensured. In Example 3-1, the particle shape of the resin filler 32c2 is spherical, whereas the particle shape of the inorganic filler 32c1 is a plate, as shown in the image diagram of FIG. As a result, it was speculated that the number of contacts was further increased to suppress the movement of the inorganic filler 32c1 and the safety was improved. The plate-like inorganic filler 32c1 has an aspect ratio of 5 or more, and in the present embodiment, a filler having a ratio of 5 to 15 was used. And the measurement of the particle size was performed using the particle size distribution measuring apparatus by a laser diffraction / scattering method.
　表２に実施例３－１に対して無機フィラー３２ｃ１の材料を変更させたときの釘刺し試験の結果を示す。実施例３－１では、無機フィラー３２ｃ１の材料にベーマイト（Ａｌ2Ｏ3水和物）を使用したのに対し、実施例４－１ではアルミナ（Ａｌ2Ｏ3）、実施例４－２ではシリカ（ＳｉＯ2）、実施例４－３では酸化チタン（ＴｉＯ2）、実施例４－４では、チタン酸バリウム（ＢａＴｉＯ2）を使用した。 Table 2 shows the results of the nail penetration test when the material of the inorganic filler 32c1 was changed with respect to Example 3-1. In Example 3-1, boehmite (Al 2 O 3 hydrate) was used as the material for the inorganic filler 32c1, whereas alumina (Al 2 O 3 ) was used in Example 4-1, and in Example 4-2. silica (SiO 2), the titanium oxide in example 4-3 (TiO 2), in example 4-4, was used barium titanate (BaTiO 2).
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２の結果から、本試験においては無機フィラー３２ｃ１の材質には依存せず、効果があることを確認した。 From the results shown in Table 2, it was confirmed that this test was effective without depending on the material of the inorganic filler 32c1.
　表３に実施例３－１に対して、セパレータ３３、３５に無機フィラー（アルミナ）３２ｃ１を塗布したセパレータ３３、３５を用いたときの釘刺し試験の結果を示す。尚、セパレータ３３、３５の塗布層は、正極側に配置するように二次電池を作製した。 Table 3 shows the results of a nail penetration test when separators 33 and 35 in which inorganic filler (alumina) 32c1 is applied to separators 33 and 35 are used in Example 3-1. In addition, the secondary battery was produced so that the coating layer of the separators 33 and 35 might be arrange | positioned at the positive electrode side.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表３の結果から、実施例５－１は、実施例３－１にくらべ、最高ＳＯＣは同じであったが、最高到達温度が減少した。これは、セパレータ３３、３５の塗布層は一般的にセパレータ３３、３５の熱収縮を抑制する効果があるため、釘を刺した周辺のセパレータ３３、３５の収縮が抑制され、釘による破断の短絡が減少したため、最高到達温度が減少したと考えられる。したがって、耐熱を高めた塗布セパレータと本実施例と組み合わせることにより、より高い安全性が期待できる。 From the results shown in Table 3, Example 5-1 had the same maximum SOC as Example 3-1 but the highest temperature reached. This is because the coated layers of the separators 33 and 35 generally have an effect of suppressing the thermal contraction of the separators 33 and 35, so that the contraction of the separators 33 and 35 around the nail is suppressed, and the break due to the nail is short-circuited. It is considered that the maximum temperature reached has decreased due to a decrease in. Therefore, higher safety can be expected by combining the coated separator with improved heat resistance and this example.
　本発明によれば、保護層３２ｃにセパレータ３３、３５や保護層３２ｃの結着材３２ｃ３よりも融点が高い樹脂フィラー３２ｃ２を混合しているので、異常発熱時において、この樹脂フィラー３２ｃ２が第二の結着材としての機能を発揮して無機フィラー３２ｃ１の動きを抑制する。したがって、セパレータ３３、３５がシュリンクしても、保護層３２ｃにより正極電極３４と負極電極３２との間の２次短絡を回避することができ、安全性を向上させることができる。 According to the present invention, the protective layer 32c is mixed with the resin filler 32c2 having a melting point higher than that of the separators 33 and 35 and the binder 32c3 of the protective layer 32c. The function as the binder is exhibited to suppress the movement of the inorganic filler 32c1. Accordingly, even if the separators 33 and 35 are shrunk, the secondary short circuit between the positive electrode 34 and the negative electrode 32 can be avoided by the protective layer 32c, and safety can be improved.
　上述の実施例では、無機フィラー３２ｃ１と樹脂フィラー３２ｃ２とを混合することで保護層３２ｃを形成する場合について説明したが、樹脂フィラー３２ｃ２を構成するＰＰＳ等の樹脂で無機フィラー３２ｃ１の少なくとも一部をコーティングしたもの、あるいは、樹脂フィラー３２ｃ２を構成する樹脂を無機フィラー３２ｃ１に担持させたものを用いてもよく、同様に安全性向上の効果を得ることができる。 In the above-described embodiment, the case where the protective layer 32c is formed by mixing the inorganic filler 32c1 and the resin filler 32c2 has been described. However, at least a part of the inorganic filler 32c1 is made of a resin such as PPS constituting the resin filler 32c2. A coated material or a resin in which the resin constituting the resin filler 32c2 is supported on the inorganic filler 32c1 may be used, and the effect of improving the safety can be obtained similarly.
　以上、本発明の実施形態について詳述したが、本発明は、前記の実施形態に限定されるものではなく、特許請求の範囲に記載された本発明の精神を逸脱しない範囲で、種々の設計変更を行うことができるものである。例えば、前記した実施の形態は本発明を分かりやすく説明するために詳細に説明したものであり、必ずしも説明した全ての構成を備えるものに限定されるものではない。また、ある実施形態の構成の一部を他の実施形態の構成に置き換えることが可能であり、また、ある実施形態の構成に他の実施形態の構成を加えることも可能である。さらに、各実施形態の構成の一部について、他の構成の追加・削除・置換をすることが可能である。 Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.
１　電池缶
３　捲回群
６　電池蓋
１０　ガス排出弁
１２　負極外部端子
１４　正極外部端子
３２　負極電極
３２ａ　負極合剤層
３２ｂ　負極金属箔露出部
３２ｃ　負極保護層
３２ｃ１　無機フィラー
３２ｃ２　樹脂フィラー
３２ｃ３　結着材
３３、３５　セパレータ
３４　正極電極
３４ａ　正極合剤層
３４ｂ　正極金属箔露出部
１００　角形二次電池（二次電池） DESCRIPTION OF SYMBOLS 1 Battery can 3 Winding group 6 Battery cover 10 Gas discharge valve 12 Negative electrode external terminal 14 Positive electrode external terminal 32 Negative electrode 32a Negative electrode mixture layer 32b Negative electrode metal foil exposed part 32c Negative electrode protective layer 32c1 Inorganic filler 32c2 Resin filler 32c3 Binder 33, 35 Separator 34 Positive electrode 34a Positive electrode mixture layer 34b Positive metal foil exposed portion 100 Square secondary battery (secondary battery)

Claims (6)

  1. 　正極電極と負極電極とをセパレータを介して積層した電極群を有する二次電池であって、
    　前記負極電極は、負極合剤層と該負極合剤層の表面に設けられた負極保護層を有し、
    　該負極保護層は、無機フィラーと、樹脂フィラーと、結着材を有し、
    　前記樹脂フィラーの融点は、前記セパレータの融点よりも高いことを特徴とする二次電池。     A secondary battery having an electrode group in which a positive electrode and a negative electrode are laminated via a separator,
    The negative electrode has a negative electrode mixture layer and a negative electrode protective layer provided on the surface of the negative electrode mixture layer,
    The negative electrode protective layer has an inorganic filler, a resin filler, and a binder.
    A secondary battery, wherein the melting point of the resin filler is higher than the melting point of the separator.
  2. 　前記樹脂フィラーは、前記無機フィラーよりも粒径が小さいことを特徴とする請求項１に記載の二次電池。 The secondary battery according to claim 1, wherein the resin filler has a particle size smaller than that of the inorganic filler.
  3. 　前記樹脂フィラーは、ポリフェニレンサルファイドを含むことを特徴とする請求項２に記載の二次電池。 The secondary battery according to claim 2, wherein the resin filler includes polyphenylene sulfide.
  4. 　前記無機フィラーは板状の粒子であり、前記樹脂フィラーは球状の粒子であることを特徴とする請求項１から請求項３のいずれか一項に記載の二次電池。 The secondary battery according to any one of claims 1 to 3, wherein the inorganic filler is a plate-like particle, and the resin filler is a spherical particle.
  5. 　前記無機フィラーは、酸化鉄、シリカ（ＳｉＯ2）、アルミナ（Ａｌ2Ｏ3）、ベーマイト（Ａｌ2Ｏ3水和物）、酸化チタン（ＴｉＯ2）、チタン酸バリウム（ＢａＴｉＯ2）の少なくともいずれか一つの材料を有することを特徴とする請求項１から請求項３のいずれか一項に記載の二次電池。 The inorganic filler is at least any one of iron oxide, silica (SiO 2 ), alumina (Al 2 O 3 ), boehmite (Al 2 O 3 hydrate), titanium oxide (TiO 2 ), and barium titanate (BaTiO 2 ). The secondary battery according to any one of claims 1 to 3, wherein the secondary battery has one material.
  6. 　前記セパレータは塗布層を有し、該塗布層は無機フィラーを有することを特徴とする請求項１から請求項３のいずれか一項に記載の二次電池。 The secondary battery according to any one of claims 1 to 3, wherein the separator has a coating layer, and the coating layer has an inorganic filler.
PCT/JP2016/072099 2015-09-02 2016-07-28 Secondary cell WO2017038327A1 (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019003770A1 (en) * 2017-06-30 2019-01-03 日立オートモティブシステムズ株式会社 Secondary battery and method for manufacturing same
CN110364667A (en) * 2018-04-11 2019-10-22 宁德新能源科技有限公司 Perforated membrane and lithium ion battery
WO2019244401A1 (en) * 2018-06-19 2019-12-26 日立オートモティブシステムズ株式会社 Lithium ion secondary battery and method for producing same
WO2022185580A1 (en) 2021-03-05 2022-09-09 ビークルエナジージャパン株式会社 Lithium ion secondary battery and method for producing same

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997001870A1 (en) * 1995-06-28 1997-01-16 Fuji Photo Film Co., Ltd. Nonaqueous secondary battery
JP2005327680A (en) * 2004-05-17 2005-11-24 Matsushita Electric Ind Co Ltd Lithium ion secondary battery
WO2006064775A1 (en) * 2004-12-13 2006-06-22 Matsushita Electric Industrial Co., Ltd. Lithium ion secondary battery
WO2008114727A1 (en) * 2007-03-15 2008-09-25 Hitachi Maxell, Ltd. Separator for electrochemical device, electrode for electrochemical device, and electrochemical device
JP2010225545A (en) * 2009-03-25 2010-10-07 Tdk Corp Electrode for lithium ion secondary battery, and lithium ion secondary battery
JP2010225539A (en) * 2009-03-25 2010-10-07 Tdk Corp Electrode for lithium ion secondary battery, and lithium ion secondary battery

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104993097B (en) * 2015-05-26 2017-06-30 广东烛光新能源科技有限公司 A kind of negative plate, the electrochemical energy storing device containing the negative plate and preparation method thereof

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997001870A1 (en) * 1995-06-28 1997-01-16 Fuji Photo Film Co., Ltd. Nonaqueous secondary battery
JP2005327680A (en) * 2004-05-17 2005-11-24 Matsushita Electric Ind Co Ltd Lithium ion secondary battery
WO2006064775A1 (en) * 2004-12-13 2006-06-22 Matsushita Electric Industrial Co., Ltd. Lithium ion secondary battery
WO2008114727A1 (en) * 2007-03-15 2008-09-25 Hitachi Maxell, Ltd. Separator for electrochemical device, electrode for electrochemical device, and electrochemical device
JP2010225545A (en) * 2009-03-25 2010-10-07 Tdk Corp Electrode for lithium ion secondary battery, and lithium ion secondary battery
JP2010225539A (en) * 2009-03-25 2010-10-07 Tdk Corp Electrode for lithium ion secondary battery, and lithium ion secondary battery

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019003770A1 (en) * 2017-06-30 2019-01-03 日立オートモティブシステムズ株式会社 Secondary battery and method for manufacturing same
JPWO2019003770A1 (en) * 2017-06-30 2020-03-19 日立オートモティブシステムズ株式会社 Secondary battery and method of manufacturing the same
CN110364667A (en) * 2018-04-11 2019-10-22 宁德新能源科技有限公司 Perforated membrane and lithium ion battery
WO2019244401A1 (en) * 2018-06-19 2019-12-26 日立オートモティブシステムズ株式会社 Lithium ion secondary battery and method for producing same
CN112335088A (en) * 2018-06-19 2021-02-05 日本汽车能源株式会社 Lithium ion secondary battery and method for manufacturing same
JPWO2019244401A1 (en) * 2018-06-19 2021-03-11 ビークルエナジージャパン株式会社 Lithium-ion secondary battery and its manufacturing method
JP7027540B2 (en) 2018-06-19 2022-03-01 ビークルエナジージャパン株式会社 Lithium-ion secondary battery and its manufacturing method
WO2022185580A1 (en) 2021-03-05 2022-09-09 ビークルエナジージャパン株式会社 Lithium ion secondary battery and method for producing same

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