WO2017098716A1 - Élément de stockage d'énergie - Google Patents

Élément de stockage d'énergie Download PDF

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Publication number
WO2017098716A1
WO2017098716A1 PCT/JP2016/005056 JP2016005056W WO2017098716A1 WO 2017098716 A1 WO2017098716 A1 WO 2017098716A1 JP 2016005056 W JP2016005056 W JP 2016005056W WO 2017098716 A1 WO2017098716 A1 WO 2017098716A1
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Prior art keywords
active material
positive electrode
peak
material layer
particle diameter
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PCT/JP2016/005056
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English (en)
Japanese (ja)
Inventor
佐々木　丈
智典 加古
祥太 伊藤
亮介 下川
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株式会社Ｇｓユアサ
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Publication of WO2017098716A1 publication Critical patent/WO2017098716A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/24—Electrodes characterised by structural features of the materials making up or comprised in the electrodes, e.g. form, surface area or porosity; characterised by the structural features of powders or particles used therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/32—Carbon-based
    • H01G11/42—Powders or particles, e.g. composition thereof
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • 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 storage element such as a lithium ion secondary battery.
  • a lithium ion secondary battery that includes a positive electrode plate having a positive electrode active material layer containing an active material, and the positive electrode active material layer contains a particulate Li—Co based composite oxide as an active material.
  • the positive electrode active material layer includes the above Li—Co-based composite oxide composed of a small particle size group having a particle size of 1 ⁇ m to 6 ⁇ m and a large particle size group having a particle size of 15 ⁇ m to 22 ⁇ m.
  • Patent Document 1 a battery in which the positive electrode active material layer includes the above Li—Co-based composite oxide composed of a small particle size group having a particle size of 1 ⁇ m to 6 ⁇ m and a large particle size group having a particle size of 15 ⁇ m to 22 ⁇ m.
  • the weight ratio of the small particle size group to the large particle size group is 0.25 to 0.60 in the positive electrode active material layer.
  • the active material having a relatively small particle size enters the gap between the active materials having a relatively large particle size, so that the active material can be sufficiently filled. . Therefore, the battery described in Patent Document 1 can have a sufficient energy density.
  • Patent Document 1 may have a sufficient energy density, it may not always have a sufficient output.
  • An object of the present invention is to provide a power storage element having a sufficient energy density and a sufficient output.
  • the electricity storage device of the present invention includes a positive electrode having an active material layer containing a particulate active material, and the active material layer is a secondary particle in which primary particles of the active material are aggregated, and is defined by voids between the primary particles. Secondary particles formed in a porous form are included as an active material, and the particle size frequency distribution of the secondary particles includes a first peak and a second peak that appears on the larger particle diameter than the first peak. And the active material layer further includes particulate graphite, the particle diameter of the first peak is 10 ⁇ m or less, the particle diameter of the second peak is larger than 10 ⁇ m, and the average particle size of the conductive auxiliary agent The diameter is greater than 10 ⁇ m.
  • the power storage device having such a configuration can have a sufficient energy density and a sufficient output.
  • the graphite may have a lower hardness than the secondary particles.
  • the active material layer can be formed by pressing during the production of the positive electrode. If the pressing force is too large, the secondary particles having voids may be crushed by the compressive force, and the void volume may be reduced.
  • the active material layer further includes graphite having a hardness lower than that of the secondary particles, the secondary particles are further suppressed from being crushed by the graphite absorbing more compressive force. Therefore, it can further suppress that the space
  • the average particle diameter of graphite may be larger than the second peak.
  • the power storage device having such a configuration can more reliably have sufficient energy density and sufficient output.
  • FIG. 1 is a perspective view of a power storage device according to this embodiment.
  • FIG. 2 is a front view of the energy storage device according to the embodiment.
  • 3 is a cross-sectional view taken along the line III-III in FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG.
  • FIG. 5 is a perspective view of a state in which a part of the energy storage device according to the embodiment is assembled, and is a perspective view of a state in which a liquid filling tap, an electrode body, a current collector, and an external terminal are assembled to a lid plate. is there.
  • FIG. 6 is a view for explaining the configuration of the electrode body of the energy storage device according to the embodiment.
  • FIG. 7 is a cross-sectional view (cross-section VII-VII in FIG. 6) of the stacked positive electrode, negative electrode, and separator.
  • FIG. 8 is a schematic cross-sectional view of secondary particles and a conductive additive in the positive electrode active material layer.
  • FIG. 9 is a perspective view of a power storage device including the power storage element according to the embodiment.
  • each component (each component) of this embodiment is a thing in this embodiment, and may differ from the name of each component (each component) in background art.
  • the electricity storage device 1 of the present embodiment is a nonaqueous electrolyte secondary battery. More specifically, the electricity storage element 1 is a lithium ion secondary battery that utilizes electron movement that occurs in association with movement of lithium ions. This type of power storage element 1 supplies electric energy.
  • the electric storage element 1 is used singly or in plural. Specifically, the storage element 1 is used as a single unit when the required output and the required voltage are small.
  • power storage element 1 is used in power storage device 100 in combination with other power storage elements 1 when at least one of a required output and a required voltage is large. In the power storage device 100, the power storage element 1 used in the power storage device 100 supplies electric energy.
  • the storage element 1 includes an electrode body 2 including a positive electrode 11 and a negative electrode 12, a case 3 that houses the electrode body 2, and an external terminal 7 that is disposed outside the case 3. And an external terminal 7 that is electrically connected to the electrode body 2.
  • the power storage element 1 includes a current collector 5 that electrically connects the electrode body 2 and the external terminal 7.
  • the electrode body 2 is formed by winding a laminated body 22 in which the positive electrode 11 and the negative electrode 12 are laminated with the separator 4 being insulated from each other.
  • the positive electrode 11 has a metal foil 111 (positive electrode base material) and an active material layer 112 that is disposed along the surface of the metal foil 111 and contains an active material.
  • the active material layer 112 overlaps each surface of the metal foil 111.
  • the active material layers 112 are respectively disposed on both sides of the metal foil 111 in the thickness direction.
  • the thickness of the positive electrode 11 is usually 40 ⁇ m or more and 150 ⁇ m or less.
  • the metal foil 111 has a strip shape.
  • the metal foil 111 of the positive electrode 11 of this embodiment is, for example, an aluminum foil.
  • the positive electrode 11 has an uncovered portion (a portion where the positive electrode active material layer is not formed) 115 of the positive electrode active material layer 112 at one edge portion in the width direction, which is the short direction of the band shape.
  • the positive electrode active material layer 112 includes a particulate active material, a particulate conductive additive C, and a binder.
  • the thickness of the positive electrode active material layer 112 (for one layer) is usually 15 ⁇ m or more and 70 ⁇ m or less.
  • the basis weight of the positive electrode active material layer 112 (for one layer) is 5 mg / cm 2 or more and 25 mg / cm 2 or less.
  • the density of the positive electrode active material layer 112 is 2 g / cm 3 or more and 4 g / cm 3 or less. The density is a density in one layer arranged so as to cover one surface of the metal foil 111.
  • the positive electrode active material layer 112 is formed to be porous by voids between the active materials.
  • the porosity of the positive electrode active material layer 112 is usually 20% or more and 50% or less.
  • the porosity can be obtained from the measurement result by the mercury intrusion method. Specifically, the porosity is obtained by calculation from the true density and bulk volume of the positive electrode active material layer 112 and the pore volume measured by the mercury intrusion method.
  • the active material of the positive electrode 11 is a compound capable of occluding and releasing lithium ions.
  • the positive electrode active material layer 112 includes secondary particles A in which a plurality of primary particles D are aggregated as an active material.
  • the positive electrode active material layer 112 includes secondary particles A in which a plurality of primary particles D are condensed as an active material.
  • the primary particles D are fixed to each other.
  • the secondary particles A are formed porous by voids between the primary particles.
  • the secondary particles A also have voids inside.
  • the secondary particles A are formed with through holes P that connect the voids inside the secondary particles A and the external spaces. That is, the internal space communicates with the space outside the particles.
  • the electrolyte solution to be described later passes through the through hole P and enters the void inside the secondary particle A. For this reason, the electrolyte solution described later enters the gap, and the secondary particles A are impregnated with the electrolyte solution.
  • the positive electrode active material layer 112 normally contains 80% by mass or more and 95% by mass or less of secondary particles A.
  • the volume-based particle size frequency distribution of the secondary particles A contained in the positive electrode active material layer 112 has a first peak and a second peak that appears on the larger particle diameter than the first peak.
  • the particle diameter of the first peak is 10 ⁇ m or less, and the particle diameter of the second peak is larger than 10 ⁇ m.
  • the peak particle size is the particle size at the peak maximum point.
  • the particle diameter D1 of the first peak is usually 1 ⁇ m or more and 10 ⁇ m or less.
  • the particle diameter D2 of the second peak is usually larger than 10 ⁇ m (more than 10 ⁇ m) and 30 ⁇ m or less, and may be 20 ⁇ m or less. Note that the above relationship between the first peak and the second peak only needs to be satisfied between adjacent peaks, and the particle size frequency distribution may have three or more peaks.
  • the frequency with respect to the particle size of the secondary particles A is represented.
  • the particle size frequency distribution is obtained by measurement using a laser diffraction / scattering type particle size distribution measuring apparatus.
  • the particle size frequency distribution is determined on the basis of the volume of the particles.
  • the electrode active material layer
  • a solvent N-methylpyrrolidone or the like
  • Undissolved material is separated by filtration and dried.
  • the particle size frequency distribution of the secondary particles A is measured using a particle size distribution measuring device.
  • the particle diameter D1 of the first peak and the particle diameter D2 of the second peak satisfy the relational expression 1 ⁇ D2 / D1 ⁇ 30.
  • the value of D2 / D1 increases the difference in the average particle diameter between the materials of the secondary particles A to be mixed. It can be adjusted by making it smaller or smaller.
  • D2 / D1 may be 2 or more and 10 or less, or 5 or less.
  • the difference between the particle diameter D1 of the first peak and the particle diameter D2 of the second peak is usually 2 ⁇ m or more and 15 ⁇ m or less, and may be 5 ⁇ m or more and 10 ⁇ m or less.
  • the difference between the average particle sizes of the secondary particles A to be mixed is increased. It can be adjusted by making it smaller.
  • the ratio of the frequency (%) of the second peak maximum point to the frequency (%) of the first peak is usually 0.1 or more and 1.0 or less.
  • Such a ratio can be adjusted, for example, by changing the mixing ratio when the materials of the secondary particles A having different average particle diameters are mixed in the production of the positive electrode 11.
  • the ratio of the particles having a particle diameter of Dx or less is that of the secondary particles A. It is 10% or more and 50% or less with respect to all particles.
  • the ratio of particles having a particle diameter of Dx or less is determined by the ratio of the area of the portion having a particle diameter of Dx or less in the particle size frequency distribution to the total area.
  • the proportion of particles having a particle size of Dx or less is usually determined by software attached to the particle size distribution measuring apparatus described above.
  • the average particle diameter of the primary particles D constituting the secondary particles A is usually 0.1 ⁇ m or more and 1 ⁇ m or less. Such an average particle diameter is obtained by measuring the diameters of at least 100 primary particles D in the scanning electron microscope observation image of the cross section in the thickness direction of the positive electrode active material layer 112 and averaging the measured values. When the primary particles D are not spherical, the longest diameter is measured as the diameter.
  • the average particle size of the secondary particles A is usually 10 ⁇ m or more and 20 ⁇ m or less. Such an average particle size is determined by obtaining a particle size corresponding to a cumulative degree of 50% (D50) in the above particle size frequency distribution.
  • the active material of the positive electrode 11 is, for example, a lithium metal oxide.
  • the active material of the positive electrode is, for example, a composite oxide (Li x Ni a O 2 , Li x Co b O represented by Li x MeO e (Me represents one or more transition metals)).
  • 2 is a Li x Mn c O 4, Li x Ni a Co b Mn c O 2 , etc.).
  • Li x Ni a Co b Mn c M d O lithium-metal composite oxide represented by the chemical composition of e, for example, LiNi 1/3 Co 1/3 Mn 1/3 O 2, LiNi 1/6 Co 2/3 Mn 1/6 O 2 , LiCoO 2 or the like.
  • the active material of the positive electrode 11 is a polyanion compound represented by the chemical composition of Li t MA y O z (where M is at least one transition metal element, and A is bonded to oxygen O to form an anion. It is a typical element, and 0 ⁇ t ⁇ 2, 1 ⁇ y ⁇ 2, 3 ⁇ z ⁇ 7).
  • the anion (A y O z ) include at least one of PO 4 3 ⁇ , BO 3 3 ⁇ , and SiO 4 4 ⁇ .
  • the transition metal of M include Fe, Mn, Co, Ni, and the like. A part of M may be substituted with a typical element such as Mg.
  • the polyanion compound is preferably represented by a chemical composition of LiMPO 4 .
  • M is preferably at least one of Fe, Mn, Co and Ni, and more preferably at least one of Mn and Fe.
  • Mn is preferably at least one of Fe, Mn, Co and Ni, and more preferably at least one of Mn and Fe.
  • the polyanionic compound Li t FePO 4, Li t MnPO 4, Li t MnSiO 4, Li t CoPO 4 F , and the like.
  • binder used for the positive electrode active material layer 112 examples include polyvinylidene fluoride (PVdF), a copolymer of ethylene and vinyl alcohol, polymethyl methacrylate, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyacrylic acid, and polymethacrylic acid. Acid, styrene butadiene rubber (SBR).
  • SBR styrene butadiene rubber
  • the conductive additive C of the positive electrode active material layer 112 contains at least graphite.
  • graphite for example, carbon materials such as ketjen black (registered trademark) and acetylene black can be included.
  • the conductive auxiliary agent C should just contain more than half of graphite by mass conversion or volume conversion, Preferably it is more.
  • graphite refers to a carbon material having an average lattice spacing (d002) of (002) plane of less than 0.340 nm determined by a wide-angle X-ray diffraction method.
  • the graphite contained in the conductive additive C of the positive electrode active material layer 112 has a lower hardness than the secondary particles of the active material.
  • the hardness of the graphite contained in the secondary particles A and the conductive additive C of the active material is measured by a dynamic ultra-micro hardness meter (model number “DUH-211S”, etc.) manufactured by Shimadzu Corporation.
  • the measurement conditions are, for example, as follows.
  • the hardness of the active material is represented by, for example, Vickers hardness. Sample: Particles are fixed with embedding resin and the surface is polished.
  • the average particle diameter of the graphite contained in the conductive additive C contained in the positive electrode active material layer 112 is usually larger than 10 ⁇ m and not larger than 20 ⁇ m.
  • the average particle size of the graphite contained in the conductive additive C is determined by determining the particle size corresponding to 50% cumulative (D50) from the particle size frequency distribution measured in the same manner as the secondary particles A. Details of the method for measuring the average particle size of graphite contained in the conductive additive C are described in the Examples.
  • the positive electrode active material layer 112 usually contains 2% by mass or more and 15% by mass or less of the conductive auxiliary agent C described above.
  • the mass ratio of the secondary particles A to the conductive aid C is usually 6 or more and 48 or less.
  • the negative electrode 12 has a metal foil 121 (negative electrode base material) and a negative electrode active material layer 122 formed on the metal foil 121.
  • the negative electrode active material layer 122 is overlaid on both surfaces of the metal foil 121.
  • the metal foil 121 has a strip shape.
  • the metal foil 121 of the negative electrode of this embodiment is, for example, a copper foil.
  • the negative electrode 12 has an uncoated portion 125 of the negative electrode active material layer 122 (a portion where the negative electrode active material layer is not formed) at one end edge in the width direction, which is the short direction of the belt shape.
  • the thickness (for one layer) of the negative electrode 12 is usually 40 ⁇ m or more and 150 ⁇ m or less.
  • the negative electrode active material layer 122 includes a particulate active material and a binder.
  • the negative electrode active material layer 122 is disposed so as to face the positive electrode 11 with the separator 4 interposed therebetween.
  • the width of the negative electrode active material layer 122 is larger than the width of the positive electrode active material layer 112.
  • the thickness of the negative electrode active material layer 122 (for one layer) is usually 10 ⁇ m or more and 50 ⁇ m or less.
  • the basis weight (one layer) of the negative electrode active material layer 122 is usually 1 mg / cm 2 or more and 8 mg / cm 2 or less.
  • the density (one layer) of the negative electrode active material layer 122 is usually 1.0 g / cm 3 or more and 1.7 g / cm 3 or less.
  • the active material of the negative electrode 12 can contribute to the electrode reaction of the charge reaction and the discharge reaction in the negative electrode 12.
  • the active material of the negative electrode 12 has an alloying reaction with carbon materials such as graphite and amorphous carbon (non-graphitizable carbon and graphitizable carbon), or lithium ions such as silicon (Si) and tin (Sn). The resulting material.
  • carbon materials such as graphite and amorphous carbon (non-graphitizable carbon and graphitizable carbon)
  • lithium ions such as silicon (Si) and tin (Sn).
  • Si silicon
  • Sn tin
  • the binder used for the negative electrode active material layer 122 is the same as the binder used for the positive electrode active material layer 112.
  • the binder of this embodiment is polyvinylidene fluoride.
  • the ratio of the binder may be 2% by mass or more and 10% by mass or less with respect to the total mass of the negative electrode active material and the binder.
  • the positive electrode 11 and the negative electrode 12 configured as described above are wound in a state where they are insulated by the separator 4. That is, in the electrode body 2 of the present embodiment, the stacked body 22 of the positive electrode 11, the negative electrode 12, and the separator 4 is wound.
  • the separator 4 is a member having insulating properties.
  • the separator 4 is disposed between the positive electrode 11 and the negative electrode 12. Thereby, in the electrode body 2 (specifically, the laminated body 22), the positive electrode 11 and the negative electrode 12 are insulated from each other.
  • the separator 4 holds the electrolytic solution in the case 3. Thereby, at the time of charging / discharging of the electrical storage element 1, lithium ion moves between the positive electrode 11 and the negative electrode 12 which are laminated
  • the separator 4 has a strip shape.
  • the separator 4 has a porous separator base material.
  • the separator 4 of this embodiment has only a separator base material.
  • the separator 4 is disposed between the positive electrode 11 and the negative electrode 12 in order to prevent a short circuit between the positive electrode 11 and the negative electrode 12.
  • the separator substrate is made of a porous material such as a woven fabric, a nonwoven fabric, or a porous film.
  • the material for the separator substrate include polymer compounds, glass, and ceramics.
  • the polymer compound include polyesters such as polyacrylonitrile (PAN), polyamide (PA), and polyethylene terephthalate (PET), polyolefins (PO) such as polypropylene (PP) and polyethylene (PE), and cellulose. .
  • the width of the separator 4 (the dimension of the strip shape in the short direction) is slightly larger than the width of the negative electrode active material layer 122.
  • the separator 4 is disposed between the positive electrode 11 and the negative electrode 12 that are stacked in a state of being displaced in the width direction so that the positive electrode active material layer 112 and the negative electrode active material layer 122 overlap. At this time, as shown in FIG. 6, the non-covered portion 115 of the positive electrode 11 and the non-covered portion 125 of the negative electrode 12 do not overlap.
  • the uncovered portion 115 of the positive electrode 11 protrudes in the width direction from the region where the positive electrode 11 and the negative electrode 12 overlap, and the non-covered portion 125 of the negative electrode 12 extends from the region where the positive electrode 11 and the negative electrode 12 overlap in the width direction ( It protrudes in a direction opposite to the protruding direction of the non-covering portion 115 of the positive electrode 11.
  • the electrode body 2 is formed by winding the stacked positive electrode 11, negative electrode 12, and separator 4, that is, the stacked body 22.
  • the portion where only the uncovered portion 115 of the positive electrode 11 or the uncovered portion 125 of the negative electrode 12 is stacked constitutes the uncoated stacked portion 26 in the electrode body 2.
  • the uncoated laminated portion 26 is a portion that is electrically connected to the current collector 5 in the electrode body 2.
  • the uncoated laminated portion 26 has two parts (divided uncoated laminated portions divided by sandwiching the hollow portion 27 (see FIG. 6) between the wound positive electrode 11, the negative electrode 12, and the separator 4 in the winding center direction. ) 261.
  • the uncoated laminated portion 26 configured as described above is provided at each electrode of the electrode body 2. That is, the non-coated laminated portion 26 in which only the non-coated portion 115 of the positive electrode 11 is laminated constitutes the non-coated laminated portion of the positive electrode 11 in the electrode body 2, and the non-coated laminated layer in which only the non-coated portion 125 of the negative electrode 12 is laminated. The portion 26 constitutes an uncoated laminated portion of the negative electrode 12 in the electrode body 2.
  • the case 3 includes a case main body 31 having an opening and a lid plate 32 that closes (closes) the opening of the case main body 31.
  • the case 3 houses the electrolytic solution in the internal space together with the electrode body 2 and the current collector 5.
  • Case 3 is formed of a metal having resistance to the electrolytic solution.
  • the case 3 is made of an aluminum-based metal material such as aluminum or an aluminum alloy, for example.
  • the case 3 may be formed of a metal material such as stainless steel and nickel, or a composite material obtained by bonding a resin such as nylon to aluminum.
  • the electrolytic solution is a non-aqueous electrolytic solution.
  • the electrolytic solution is obtained by dissolving an electrolyte salt in an organic solvent.
  • the organic solvent include cyclic carbonates such as propylene carbonate and ethylene carbonate, and chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.
  • the electrolyte salt is LiClO 4 , LiBF 4 , LiPF 6 or the like.
  • the electrolytic solution of this embodiment is obtained by dissolving 0.5 to 1.5 mol / L of LiPF 6 in a mixed solvent in which ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate are mixed at a predetermined ratio.
  • the case 3 is formed by joining the peripheral edge of the opening of the case main body 31 and the peripheral edge of the rectangular lid plate 32 in an overlapping state.
  • the case 3 has an internal space defined by the case main body 31 and the lid plate 32.
  • the opening peripheral part of the case main body 31 and the peripheral part of the cover plate 32 are joined by welding.
  • the long side direction of the cover plate 32 is the X-axis direction
  • the short side direction of the cover plate 32 is the Y-axis direction
  • the normal direction of the cover plate 32 is the Z-axis direction.
  • the case main body 31 has a rectangular tube shape (that is, a bottomed rectangular tube shape) in which one end in the opening direction (Z-axis direction) is closed.
  • the lid plate 32 is a plate-like member that closes the opening of the case body 31.
  • the lid plate 32 has a gas discharge valve 321 that can discharge the gas in the case 3 to the outside.
  • the gas discharge valve 321 discharges gas from the inside of the case 3 to the outside when the internal pressure of the case 3 rises to a predetermined pressure.
  • the gas discharge valve 321 is provided at the center of the lid plate 32 in the X-axis direction.
  • Case 3 is provided with a liquid injection hole for injecting an electrolytic solution.
  • the liquid injection hole communicates the inside and the outside of the case 3.
  • the liquid injection hole is provided in the lid plate 32.
  • the liquid injection hole is sealed (closed) by a liquid injection stopper 326.
  • the liquid filling tap 326 is fixed to the case 3 (the cover plate 32 in the example of the present embodiment) by welding.
  • the external terminal 7 is a part that is electrically connected to the external terminal 7 of another power storage element 1 or an external device.
  • the external terminal 7 is formed of a conductive member.
  • the external terminal 7 is formed of a highly weldable metal material such as an aluminum-based metal material such as aluminum or aluminum alloy, or a copper-based metal material such as copper or copper alloy.
  • the external terminal 7 has a surface 71 on which a bus bar or the like can be welded.
  • the surface 71 is a flat surface.
  • the external terminal 7 has a plate shape extending along the lid plate 32. Specifically, the external terminal 7 has a rectangular plate shape when viewed in the Z-axis direction.
  • the current collector 5 is disposed in the case 3 and is directly or indirectly connected to the electrode body 2 so as to be energized.
  • the current collector 5 of the present embodiment is connected to the electrode body 2 through the clip member 50 so as to be energized. That is, the electrical storage element 1 includes a clip member 50 that connects the electrode body 2 and the current collector 5 so as to allow energization.
  • the current collector 5 is formed of a conductive member. As shown in FIG. 3, the current collector 5 is disposed along the inner surface of the case 3. The current collector 5 is disposed on each of the positive electrode 11 and the negative electrode 12 of the power storage element 1. In the power storage device 1 of the present embodiment, the case 3 is arranged in the uncoated stacked portion 26 of the positive electrode 11 and the uncoated stacked portion 26 of the negative electrode 12 in the electrode body 2.
  • the current collector 5 of the positive electrode 11 and the current collector 5 of the negative electrode 12 are formed of different materials. Specifically, the current collector 5 of the positive electrode 11 is formed of, for example, aluminum or an aluminum alloy, and the current collector 5 of the negative electrode 12 is formed of, for example, copper or a copper alloy.
  • the electrode body 2 (specifically, the electrode body 2 and the current collector 5) housed in a bag-like insulating cover 6 that insulates the electrode body 2 and the case 3 is the case 3. Housed inside.
  • the mixture containing an active material is apply
  • the positive electrode 11, the separator 4, and the negative electrode 12 are overlapped to form the electrode body 2.
  • the electrode body 2 is put in the case 3 and the electrolytic solution is put in the case 3 to assemble the power storage element 1.
  • the positive electrode active material layer 112 is formed by applying a mixture containing an active material, a binder, and a solvent to both surfaces of the metal foil.
  • a coating method for forming the positive electrode active material layer 112 a general method is employed.
  • the applied positive electrode active material layer 112 is roll-pressed at a predetermined temperature (for example, 80 to 150 ° C.) and a predetermined pressure (for example, a linear pressure of 50 to 500 kg / cm).
  • the density of the positive electrode active material layer 112 can be adjusted by adjusting the pressing pressure. After pressing, vacuum drying is performed at 80 to 140 ° C. for 12 to 24 hours.
  • the negative electrode is produced in the same manner.
  • the electrode body 2 is formed by winding the laminated body 22 with the separator 4 sandwiched between the positive electrode 11 and the negative electrode 12. Specifically, the positive electrode 11, the separator 4, and the negative electrode 12 are overlapped so that the positive electrode active material layer 112 and the negative electrode active material layer 122 face each other through the separator 4, thereby forming the laminate 22. Subsequently, the stacked body 22 is wound to form the electrode body 2.
  • the electrode body 2 is inserted into the case body 31 of the case 3, the opening of the case body 31 is closed with the cover plate 32, and the electrolytic solution is injected into the case 3.
  • the electrode body 2 is inserted into the case main body 31, the positive electrode 11 and the one external terminal 7 are electrically connected, and the negative electrode 12 and the other external terminal 7 are connected to each other.
  • the opening of the case body 31 is closed with the lid plate 32.
  • the particle size frequency distribution of the secondary particles A as the active material of the positive electrode 11 based on the volume is based on the first peak and the first peak. Also have a second peak that appears on the larger particle diameter.
  • the particle size frequency distribution of the secondary particles A has a first peak with a particle size of 10 ⁇ m or less and a second peak with a particle size greater than 10 ⁇ m.
  • the positive electrode active material layer 112 as shown in FIG. 8, the secondary particles A ′′ having a smaller particle diameter are likely to enter the gaps between the secondary particles A ′ having a larger particle diameter and closer to each other.
  • the active material layer 112 is sufficiently filled with the secondary particles A.
  • the positive electrode active material layer 112 is easily consolidated even when the press pressure is relatively small. It can have a sufficient density.
  • the secondary particles A of the positive electrode active material are formed to be porous by voids between the primary particles constituting the secondary particles A. Since the secondary particles A as the active material are porous, a discharge reaction occurs not only on the outer surface of the secondary particles A but also on the inner surface. Since the discharge reaction occurs on the inner surface of the secondary particle A, the output can be increased. And the secondary particle A can hold
  • the positive electrode active material layer 112 includes secondary particles A and graphite contained in the particulate conductive additive C.
  • the positive electrode active material layer 112 can be formed by pressing when the positive electrode 11 is manufactured. When the pressing force is too large, the positive electrode active material layer 112 receives a compressive force that is too large, and the secondary particles A having voids therein are crushed, and the volume of the voids can be reduced. However, since the positive electrode active material layer 112 further includes graphite contained in the conductive additive C, the secondary particles A are crushed when the graphite contained in the conductive additive C absorbs compressive force as a slipping agent. It can suppress that a space
  • the power storage element 1 can have a sufficient output.
  • the graphite contained in the conductive auxiliary agent C has a hardness lower than that of the secondary particles A, the secondary particles A are more reliably crushed and voids are reduced by more easily absorbing the compressive force. Can be suppressed. Therefore, it can suppress that the quantity of the electrolyte solution which the secondary particle A can hold
  • the average particle diameter of graphite contained in the conductive additive C of the positive electrode active material layer 112 is larger than 10 ⁇ m. That is, the positive electrode active material layer 112 includes secondary particles A ′′ that are smaller than the graphite contained in the conductive auxiliary agent C. Accordingly, the gap between the graphite contained in the conductive auxiliary agent C that is close to each other is relatively small. Secondary particles A ′′ are easily filled. Thereby, it is possible to reliably suppress the relatively small secondary particles A ′′ from being crushed by the compressive force as described above by the graphite contained in the conductive additive C for the same reason as described above.
  • the power storage element 1 can have a sufficient output.
  • the electric storage element of the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention.
  • the configuration of another embodiment can be added to the configuration of a certain embodiment, and a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment.
  • a part of the configuration of an embodiment can be deleted.
  • the particle size frequency distribution of the secondary particles A has a first peak that appears when the particle size is smaller and a second peak that appears when the particle size is larger, and the first peak
  • the first peak and the second peak are not necessarily adjacent to each other.
  • the frequency between the first peak and the second peak is smaller than any of the peaks (peak Even if a small peak (having a low height) appears, the peaks appearing on both sides of the small peak may be used as the first peak and the second peak, respectively.
  • the positive electrode in which the active material layer is in direct contact with the metal foil has been described in detail.
  • the positive electrode has a conductive layer containing a conductive additive and a binder between the active material layer and the metal foil. You may have.
  • the electrodes in which the active material layers are disposed on both sides of the metal foil of each electrode have been described.
  • the positive electrode 11 or the negative electrode 12 has the active material layer on one side of the metal foil. It may be provided only on the side.
  • the power storage element 1 including the electrode body 2 in which the multilayer body 22 is wound has been described in detail.
  • the power storage element of the present invention may include the multilayer body 22 that is not wound.
  • the storage element may include an electrode body in which a positive electrode, a separator, a negative electrode, and a separator each formed in a rectangular shape are stacked a plurality of times in this order.
  • the power storage element 1 is used as a chargeable / dischargeable non-aqueous electrolyte secondary battery (for example, a lithium ion secondary battery) has been described.
  • the type and size (capacity) of the power storage element 1 are arbitrary. is there.
  • the lithium ion secondary battery was demonstrated as an example of the electrical storage element 1 in the said embodiment, it is not limited to this.
  • the present invention can be applied to various secondary batteries, other primary batteries, and electric storage elements of capacitors such as electric double layer capacitors and lithium ion capacitors.
  • the power storage device 1 (for example, a battery) may be used in a power storage device 100 as shown in FIG. 9 (a battery module when the power storage device is a battery).
  • the power storage device 100 includes at least two power storage elements 1 and a bus bar member 91 that electrically connects two (different) power storage elements 1 to each other.
  • the technique of the present invention may be applied to at least one power storage element.
  • a nonaqueous electrolyte secondary battery (lithium ion secondary battery) was produced as shown below.
  • Example 1 Preparation of positive electrode
  • two types of secondary particles having different average particle diameters were used.
  • the details of the active material are as follows.
  • the blending amount of the binder was 5% by mass.
  • the compounding ratio (mass ratio) of the active material (secondary particles having a small particle size) and the active material (secondary particles having a large particle size) was 25:65.
  • the prepared positive electrode mixture was applied to a metal foil so that the coating amount (weight per unit area) after drying was 8 mg / cm 2 . After drying, a roll press was performed. Thereafter, it was vacuum dried to remove moisture and the like.
  • the thickness of the active material layer (for one layer) after pressing was 30 ⁇ m.
  • the density of the active material layer was 2.5 g / cm 3 .
  • the porosity of the active material layer was 35%.
  • the negative electrode mixture was prepared by mixing and kneading NMP as a solvent, a binder, and an active material.
  • the binder was blended so as to be 7% by mass, and the active material was blended so as to be 93% by mass.
  • the prepared negative electrode mixture was applied to both surfaces of a copper foil (thickness: 10 ⁇ m) so that the coating amount (weight per unit area) after drying was 4.0 mg / cm 2 . After drying, roll pressing was performed and vacuum drying was performed to remove moisture and the like.
  • the thickness of the active material layer (for one layer) was 35 ⁇ m.
  • the density of the active material layer was 1.2 g / cm 3 .
  • Separator A polyethylene microporous film having a thickness of 22 ⁇ m was used as a separator.
  • the air permeability of the polyethylene microporous membrane was 100 seconds / 100 cc.
  • electrolytic solution one prepared by the following method was used.
  • ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate were all mixed by 1 part by mass, and LiPF 6 was dissolved in the non-aqueous solvent so that the salt concentration was 1 mol / L.
  • An electrolyte solution was prepared.
  • the particle size frequency distribution of the active material (secondary particle) in the active material layer of a positive electrode was taken out from the battery once manufactured.
  • the electrode (active material layer) was taken out and immersed in N-methylpyrrolidone (NMP) to dissolve the binder. Undissolved material was separated by filtration and dried. Thereafter, the particle size frequency distribution of the active material was measured using a particle size distribution measuring device.
  • a laser diffraction particle size distribution measuring device (“SALD2200” manufactured by Shimadzu Corporation) was used as a measuring device, and a dedicated application software DMS ver2 was used as measurement control software.
  • a scattering measurement mode is adopted, and a wet cell in which a dispersion liquid in which a measurement sample (active material) is dispersed is placed in an ultrasonic environment for 2 minutes, and then laser light is irradiated.
  • the scattered light distribution was obtained from the measurement sample.
  • the scattered light distribution is approximated by a lognormal distribution, and in the particle size frequency distribution (horizontal axis, ⁇ ), the particle size is measured within a range in which the minimum is set to 0.021 ⁇ m and the maximum is set to 2000 ⁇ m. Distribution was obtained.
  • the dispersion was composed of a surfactant and SN Dispersant 7347-C (product name) or Triton X- 100 (product name).
  • particle diameter D1 of the first peak particle diameter D2 of the second peak
  • particle diameter D1 of the first peak particle diameter D1 of the first peak.
  • the particle diameter D1 was 6 ⁇ m.
  • the particle diameter at the maximum point of the peak having the larger particle diameter was defined as the particle diameter D2 of the second peak.
  • the particle diameter D2 was 15 ⁇ m.
  • Examples 2 to 9 A lithium ion secondary battery was manufactured in the same manner as in Example 1 except that the battery was changed to have the configuration shown in Table 1.
  • the compounding ratio (mass ratio) of the secondary particle with a small particle size and the secondary particle with a large particle size was 25:65.
  • blended the conductive support agent (graphite) with the active material layer the compounding quantity of the conductive support agent was 10 mass%. The following were used as conductive assistants.
  • Average particle size 19 ⁇ m Vickers hardness Hv 10 -Average particle diameter of conductive auxiliary agent (graphite) The particle diameter was measured in the same manner as the measurement of the particle size frequency distribution of the secondary particles except that the conductive auxiliary agent was separated from the active material. In the particle size frequency distribution, the particle size corresponding to a cumulative degree of 50% (D50) was defined as the average particle size. Note that the above-described mass ratio of the secondary particles having a small particle size to the secondary particles having a large particle size, and the blending amounts shown in Table 1 of the conductive aid in the active material layer are merely specific examples. As described above, any power storage element having the first peak and the second peak appearing on the larger particle diameter than the first peak is included in the present invention.
  • the energy density was sufficient and the output performance was sufficiently exhibited.
  • either the energy density or the output performance of the battery of the comparative example was not always sufficient.
  • 1 Power storage element (non-aqueous electrolyte secondary battery), 2: Electrode body, 26: Uncoated laminated part, 3: Case, 31: Case body, 32: Cover plate, 4: Separator, 5: current collector, 50: clip member, 6: Insulation cover 7: External terminal, 71: Surface, 11: positive electrode, 111: Metal foil of positive electrode (positive electrode base material), 112: Positive electrode active material layer, 12: negative electrode, 121: negative electrode metal foil (negative electrode substrate), 122: negative electrode active material layer, 91: Bus bar member, 100: Power storage device.

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  • Chemical & Material Sciences (AREA)
  • Power Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
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  • Microelectronics & Electronic Packaging (AREA)
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Abstract

L'invention concerne un élément de stockage d'énergie qui présente une densité d'énergie plus adéquate et une production en sortie plus adéquate. L'élément de stockage d'énergie selon l'invention est pourvu d'une électrode positive qui a une couche de substance active contenant une substance active particulaire. En tant que substance active, la couche de substance active contient des particules secondaires, agrégats de particules primaires de la substance active, qui sont rendues poreuses par les vides entre les particules primaires. La distribution de fréquence de diamètre de particule des particules secondaires présente un premier pic et un second pic apparaissant à un diamètre de particule supérieur à celui du premier pic. La couche de substance active contient en outre un graphite particulaire, le diamètre de particule au niveau du premier pic est inférieur ou égal à 10 µm et le diamètre de particule au niveau du second pic est supérieur à 10 μm et le diamètre moyen de particule d'un agent favorisant la conduction est supérieur à 10 µm.
PCT/JP2016/005056 2015-12-08 2016-12-05 Élément de stockage d'énergie WO2017098716A1 (fr)

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JP2017174738A (ja) * 2016-03-25 2017-09-28 株式会社Ｇｓユアサ 蓄電素子
EP3509137A4 (fr) * 2016-09-07 2020-05-06 GS Yuasa International Ltd. Élément de stockage d'électricité et procédé de production d'élément de stockage d'électricité
JP2020194708A (ja) * 2019-05-28 2020-12-03 株式会社Ｇｓユアサ 非水電解質蓄電素子の製造方法及び非水電解質蓄電素子
WO2023224071A1 (fr) * 2022-05-20 2023-11-23 株式会社Ｇｓユアサ Élément de stockage d'énergie à électrolyte non aqueux

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WO2014061399A1 (fr) * 2012-10-15 2014-04-24 日本碍子株式会社 Matériau actif positif pour batterie secondaire au lithium, et électrode positive obtenue à l'aide de celui-ci
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JPH1186845A (ja) * 1997-09-05 1999-03-30 Asahi Chem Ind Co Ltd 非水系二次電池
JPH11283628A (ja) * 1998-03-30 1999-10-15 Fuji Photo Film Co Ltd 非水二次電池
JP2000082466A (ja) * 1998-07-02 2000-03-21 Nippon Chem Ind Co Ltd 正極活物質及び非水電解質二次電池
JP2013065467A (ja) * 2011-09-16 2013-04-11 Panasonic Corp リチウムイオン二次電池
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JP2017174738A (ja) * 2016-03-25 2017-09-28 株式会社Ｇｓユアサ 蓄電素子
EP3509137A4 (fr) * 2016-09-07 2020-05-06 GS Yuasa International Ltd. Élément de stockage d'électricité et procédé de production d'élément de stockage d'électricité
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JP2020194708A (ja) * 2019-05-28 2020-12-03 株式会社Ｇｓユアサ 非水電解質蓄電素子の製造方法及び非水電解質蓄電素子
JP7215331B2 (ja) 2019-05-28 2023-01-31 株式会社Ｇｓユアサ 非水電解質蓄電素子の製造方法及び非水電解質蓄電素子
WO2023224071A1 (fr) * 2022-05-20 2023-11-23 株式会社Ｇｓユアサ Élément de stockage d'énergie à électrolyte non aqueux

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