WO2013051155A1 - リチウムイオン二次電池 - Google Patents
リチウムイオン二次電池 Download PDFInfo
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- WO2013051155A1 WO2013051155A1 PCT/JP2011/073249 JP2011073249W WO2013051155A1 WO 2013051155 A1 WO2013051155 A1 WO 2013051155A1 JP 2011073249 W JP2011073249 W JP 2011073249W WO 2013051155 A1 WO2013051155 A1 WO 2013051155A1
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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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
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- 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
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- 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
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- 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
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
Definitions
- the present invention relates to a lithium ion secondary battery.
- second battery refers to a battery that can be repeatedly charged, and includes so-called storage batteries such as lithium secondary batteries (typically lithium ion secondary batteries) and nickel metal hydride batteries.
- active material refers to reversibly occlusion and release (typically insertion and removal) of a chemical species that serves as a charge carrier in a secondary battery (for example, lithium ions in a lithium ion secondary battery). A possible substance.
- Japanese Patent Application Publication No. Heisei 05-290844 discloses a lithium ion secondary battery using a LiPF 6- containing electrolyte as a negative electrode material capable of occluding and releasing lithium, and natural graphite and artificial graphite.
- the use of a mixture is disclosed.
- the mixture contains 10 to 50% by weight of artificial graphite. According to this configuration, it is disclosed that a rapid reaction between LiPF 6 and the carbon material can be suppressed.
- Japanese Patent Application Publication No. 2009-64574 has a plurality of negative electrode layers on a negative electrode current collector, and is farther from the negative electrode current collector than a negative electrode layer closer to the negative electrode current collector.
- a lithium ion secondary battery having a high charge rate characteristic of the negative electrode layer on the side has been proposed.
- the lithium ion secondary battery occludes lithium ions released from the positive electrode during charging in the negative electrode.
- the width of the negative electrode active material layer is increased with respect to the positive electrode active material layer that releases lithium ions. Covers the positive electrode active material layer. In such a form, it is difficult to achieve both a low reaction resistance (battery resistance) and a high capacity maintenance rate.
- a lithium ion secondary battery includes a positive electrode current collector, a positive electrode active material layer held by the positive electrode current collector, a negative electrode current collector, and a negative electrode current collector, A negative electrode active material layer disposed to cover the positive electrode active material layer.
- the negative electrode active material layer contains natural graphite and artificial graphite as negative electrode active material particles.
- the negative electrode active material layer has a portion facing the positive electrode active material layer and a portion not facing the positive electrode active material layer.
- the ratio of natural graphite is larger than in the part not facing the positive electrode active material layer, and in the part not facing the positive electrode active material layer, the positive electrode active material layer.
- the ratio of artificial graphite is larger than that of the part facing the surface. According to this configuration, the reaction resistance (battery resistance) can be kept low, and the capacity retention rate can be kept high.
- the weight ratio of natural graphite in natural graphite and artificial graphite may be 90% or more.
- the weight ratio of artificial graphite may be 90% or more among natural graphite and artificial graphite.
- Natural graphite may have an R value in the Raman spectroscopy of 0.2 to 0.6, and artificial graphite may have an R value of 0.2 or less.
- part which is not facing the average R value (Ra) of the negative electrode active material particle used for the site
- the ratio (Ra / Rb) to the average R value (Rb) of the negative electrode active material particles may be (Ra / Rb) ⁇ 1.2.
- the R value means the R value in Raman spectroscopy.
- the negative electrode active material layer includes a binder, and the portion of the negative electrode active material layer that does not face the positive electrode active material layer is compared with the portion of the negative electrode active material layer that faces the positive electrode active material layer, A high binder content is preferred.
- Natural graphite may be at least partially covered with an amorphous carbon film.
- FIG. 1 is a diagram illustrating an example of the structure of a lithium ion secondary battery.
- FIG. 2 is a view showing a wound electrode body of a lithium ion secondary battery.
- FIG. 3 is a cross-sectional view showing a III-III cross section in FIG.
- FIG. 4 is a cross-sectional view showing the structure of the positive electrode active material layer.
- FIG. 5 is a cross-sectional view showing the structure of the negative electrode active material layer.
- FIG. 6 is a side view showing a welding location between an uncoated portion of the wound electrode body and the electrode terminal.
- FIG. 7 is a diagram schematically illustrating a state of the lithium ion secondary battery during charging.
- FIG. 8 is a diagram schematically showing a state of the lithium ion secondary battery during discharge.
- FIG. 9 is a diagram showing a lithium ion secondary battery according to an embodiment of the present invention.
- FIG. 10 is a cross-sectional view showing a laminated structure of a positive electrode sheet and a negative electrode sheet of a wound electrode body in a lithium ion secondary battery according to an embodiment of the present invention.
- FIG. 11 is a cross-sectional view schematically showing the structure of a lithium ion secondary battery according to an embodiment of the present invention.
- FIG. 12 is a diagram illustrating a process of forming a negative electrode active material layer.
- FIG. 13 is a diagram illustrating an example of a die used for forming the negative electrode active material layer.
- FIG. 14 is a diagram showing a typical example of a Cole-Cole plot (Nyquist plot) in the AC impedance measurement method.
- FIG. 15 shows the reaction resistance (m ⁇ ) at ⁇ 30 ° C. and the capacity retention rate (%) after storage for Samples 1 to 5.
- FIG. 16 is a diagram showing the relationship between the 150-time tap density and the peel strength for the negative electrode active material particles.
- FIG. 17 is a diagram showing a 90-degree peel adhesion strength test method.
- FIG. 18 is a side view schematically showing a vehicle (automobile) provided with a non-aqueous secondary battery (vehicle driving battery) according to an embodiment of the present invention.
- FIG. 1 shows a lithium ion secondary battery 100.
- the lithium ion secondary battery 100 includes a wound electrode body 200 and a battery case 300.
- FIG. 2 is a view showing the wound electrode body 200.
- FIG. 3 shows a III-III cross section in FIG.
- the wound electrode body 200 includes a positive electrode sheet 220, a negative electrode sheet 240, and separators 262 and 264.
- the positive electrode sheet 220, the negative electrode sheet 240, and the separators 262 and 264 are respectively strip-shaped sheet materials.
- the positive electrode sheet 220 includes a strip-shaped positive electrode current collector 221 and a positive electrode active material layer 223.
- a metal foil suitable for the positive electrode can be suitably used.
- a strip-shaped aluminum foil having a predetermined width and a thickness of approximately 15 ⁇ m can be used.
- An uncoated portion 222 is set along the edge on one side in the width direction of the positive electrode current collector 221.
- the positive electrode active material layer 223 is held on both surfaces of the positive electrode current collector 221 except for the uncoated portion 222 set on the positive electrode current collector 221 as shown in FIG.
- the positive electrode active material layer 223 contains a positive electrode active material.
- the positive electrode active material layer 223 is formed by applying a positive electrode mixture containing a positive electrode active material to the positive electrode current collector 221.
- FIG. 4 is a cross-sectional view of the positive electrode sheet 220.
- the positive electrode active material particles 610, the conductive material 620, and the binder 630 in the positive electrode active material layer 223 are schematically illustrated so that the structure of the positive electrode active material layer 223 becomes clear.
- the positive electrode active material layer 223 includes positive electrode active material particles 610, a conductive material 620, and a binder 630.
- the positive electrode active material particles 610 a material that can be used as a positive electrode active material of a lithium ion secondary battery can be used.
- the positive electrode active material particles 610 include LiNiCoMnO 2 (lithium nickel cobalt manganese composite oxide), LiNiO 2 (lithium nickelate), LiCoO 2 (lithium cobaltate), LiMn 2 O 4 (lithium manganate), LiFePO And lithium transition metal oxides such as 4 (lithium iron phosphate).
- LiMn 2 O 4 has, for example, a spinel structure.
- LiNiO 2 or LiCoO 2 has a layered rock salt structure.
- LiFePO 4 has, for example, an olivine structure.
- LiFePO 4 having an olivine structure includes, for example, nanometer order particles.
- LiFePO 4 having an olivine structure can be further covered with a carbon film.
- the conductive material 620 examples include carbon materials such as carbon powder and carbon fiber.
- the conductive material 620 one kind selected from such conductive materials may be used alone, or two or more kinds may be used in combination.
- the carbon powder various carbon blacks (for example, acetylene black, oil furnace black, graphitized carbon black, carbon black, graphite, ketjen black), graphite powder, and the like can be used.
- the binder 630 binds the positive electrode active material particles 610 and the conductive material 620 included in the positive electrode active material layer 223, or binds these particles and the positive electrode current collector 221.
- a polymer that can be dissolved or dispersed in a solvent to be used can be used as the binder 630.
- a cellulose polymer (carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC), etc.), a fluorine resin (eg, polyvinyl alcohol (PVA), polytetrafluoroethylene, etc.) (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP, etc.), rubbers (vinyl acetate copolymer, styrene butadiene copolymer (SBR), acrylic acid-modified SBR resin (SBR latex), etc.)
- a water-soluble or water-dispersible polymer such as can be preferably used.
- a polymer polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), polyacrylonitrile (PAN), etc.
- PVDF polyvinylidene fluoride
- PVDC polyvinylidene chloride
- PAN polyacrylonitrile
- the positive electrode active material layer 223 is prepared, for example, by preparing a positive electrode mixture in which the above-described positive electrode active material particles 610 and the conductive material 620 are mixed in a paste (slurry) with a solvent, applied to the positive electrode current collector 221, and dried. And is formed by rolling.
- a solvent for the positive electrode mixture either an aqueous solvent or a non-aqueous solvent can be used.
- a preferred example of the non-aqueous solvent is N-methyl-2-pyrrolidone (NMP).
- NMP N-methyl-2-pyrrolidone
- the polymer material exemplified as the binder 630 may be used for the purpose of exhibiting a function as a thickener or other additive of the positive electrode mixture in addition to the function as a binder.
- the mass ratio of the positive electrode active material in the total positive electrode mixture is preferably about 50 wt% or more (typically 50 to 95 wt%), and usually about 70 to 95 wt% (for example, 75 to 90 wt%). It is more preferable. Further, the ratio of the conductive material to the whole positive electrode mixture can be, for example, about 2 to 20 wt%, and is usually preferably about 2 to 15 wt%. In the composition using the binder, the ratio of the binder to the whole positive electrode mixture can be, for example, about 1 to 10 wt%, and usually about 2 to 5 wt%.
- the negative electrode sheet 240 includes a strip-shaped negative electrode current collector 241 and a negative electrode active material layer 243.
- a metal foil suitable for the negative electrode can be suitably used.
- the negative electrode current collector 241 is made of a strip-shaped copper foil having a predetermined width and a thickness of about 10 ⁇ m.
- an uncoated part 242 is set along the edge.
- the negative electrode active material layer 243 is formed on both surfaces of the negative electrode current collector 241 except for the uncoated portion 242 set on the negative electrode current collector 241.
- the negative electrode active material layer 243 is held by the negative electrode current collector 241 and contains at least a negative electrode active material.
- a negative electrode mixture containing a negative electrode active material is applied to the negative electrode current collector 241.
- FIG. 5 is a cross-sectional view of the negative electrode sheet 240 of the lithium ion secondary battery 100.
- the negative electrode active material layer 243 includes negative electrode active material particles 710, a thickener (not shown), a binder 730, and the like.
- the negative electrode active material particles 710 and the binder 730 in the negative electrode active material layer 243 are schematically illustrated so that the structure of the negative electrode active material layer 243 becomes clear.
- Negative Electrode Active Material Particles 710 one or two or more materials conventionally used for lithium ion secondary batteries can be used as the negative electrode active material without any particular limitation.
- the negative electrode active material is, for example, natural graphite, natural graphite coated with an amorphous carbon material, graphite (graphite), non-graphitizable carbon (hard carbon), graphitizable carbon ( Soft carbon) or a carbon material combining these may be used.
- the negative electrode active material particles 710 are illustrated using so-called scaly graphite, but the negative electrode active material particles 710 are not limited to the illustrated example.
- the negative electrode active material layer 243 is prepared, for example, by preparing a negative electrode mixture in which the negative electrode active material particles 710 and the binder 730 described above are mixed in a paste (slurry) with a solvent, and applied to the negative electrode current collector 241 and dried. It is formed by rolling. At this time, any of an aqueous solvent and a non-aqueous solvent can be used as the solvent for the negative electrode mixture.
- a preferred example of the non-aqueous solvent is N-methyl-2-pyrrolidone (NMP).
- NMP N-methyl-2-pyrrolidone
- the binder 730 the polymer material exemplified as the binder 630 of the positive electrode active material layer 223 (see FIG. 4) can be used.
- the polymer material exemplified as the binder 630 of the positive electrode active material layer 223 may be used for the purpose of exhibiting a function as a thickener or other additive of the positive electrode mixture in addition to the function as a binder. possible.
- the separators 262 and 264 are members that separate the positive electrode sheet 220 and the negative electrode sheet 240 as shown in FIG. 1 or FIG.
- the separators 262 and 264 are made of a strip-shaped sheet material having a predetermined width and having a plurality of minute holes.
- a single layer structure separator or a multilayer structure separator made of a porous polyolefin resin can be used as the separators 262 and 264.
- the width b1 of the negative electrode active material layer 243 is slightly wider than the width a1 of the positive electrode active material layer 223.
- the widths c1 and c2 of the separators 262 and 264 are slightly wider than the width b1 of the negative electrode active material layer 243 (c1, c2>b1> a1).
- the separators 262 and 264 are made of sheet-like members.
- the separators 262 and 264 may be members that insulate the positive electrode active material layer 223 and the negative electrode active material layer 243 and allow the electrolyte to move. Therefore, it is not limited to a sheet-like member.
- the separators 262 and 264 may be formed of a layer of insulating particles formed on the surface of the positive electrode active material layer 223 or the negative electrode active material layer 243, for example, instead of the sheet-like member.
- the particles having insulating properties inorganic fillers having insulating properties (for example, fillers such as metal oxides and metal hydroxides) or resin particles having insulating properties (for example, particles such as polyethylene and polypropylene). ).
- the positive electrode sheet 220 and the negative electrode sheet 240 have a positive electrode active material layer 223 and a negative electrode active material layer 243 with separators 262 and 264 interposed therebetween. Are stacked so that they face each other. More specifically, in the wound electrode body 200, the positive electrode sheet 220, the negative electrode sheet 240, and the separators 262 and 264 are stacked in the order of the positive electrode sheet 220, the separator 262, the negative electrode sheet 240, and the separator 264.
- the positive electrode active material layer 223 and the negative electrode active material layer 243 are opposed to each other with the separators 262 and 264 interposed therebetween. Then, on one side of the portion where the positive electrode active material layer 223 and the negative electrode active material layer 243 face each other, a portion of the positive electrode current collector 221 where the positive electrode active material layer 223 is not formed (uncoated portion 222) protrudes. Yes. A portion of the negative electrode current collector 241 where the negative electrode active material layer 243 is not formed (uncoated portion 242) protrudes on the side opposite to the side where the uncoated portion 222 protrudes. Further, the positive electrode sheet 220, the negative electrode sheet 240, and the separators 262 and 264 are wound along the winding axis WL set in the width direction of the positive electrode sheet 220 in a state where they are overlapped in this way.
- the battery case 300 is a so-called square battery case, and includes a container body 320 and a lid 340.
- the container main body 320 has a bottomed rectangular tube shape and is a flat box-shaped container having one side surface (upper surface) opened.
- the lid 340 is a member that is attached to the opening (opening on the upper surface) of the container body 320 and closes the opening.
- the container main body 320 and the lid body 340 constituting the battery case 300 are made of a lightweight metal such as aluminum or an aluminum alloy. Thereby, weight energy efficiency can be improved.
- the battery case 300 has a flat rectangular internal space as a space for accommodating the wound electrode body 200. Further, as shown in FIG. 1, the flat internal space of the battery case 300 is slightly wider than the wound electrode body 200.
- the battery case 300 includes a bottomed rectangular tubular container body 320 and a lid 340 that closes the opening of the container body 320. Electrode terminals 420 and 440 are attached to the lid 340 of the battery case 300. The electrode terminals 420 and 440 pass through the battery case 300 (lid 340) and come out of the battery case 300.
- the lid 340 is provided with a liquid injection hole 350 and a safety valve 360.
- the wound electrode body 200 is flatly pushed and bent in one direction orthogonal to the winding axis WL.
- the uncoated part 222 of the positive electrode current collector 221 and the uncoated part 242 of the negative electrode current collector 241 are spirally exposed on both sides of the separators 262 and 264, respectively.
- the intermediate portions 224 and 244 of the uncoated portions 222 and 242 are gathered together and welded to the tip portions 420 a and 440 a of the electrode terminals 420 and 440.
- ultrasonic welding is used for welding the electrode terminal 420 and the positive electrode current collector 221 due to the difference in materials.
- FIG. 6 is a side view showing a welded portion between the intermediate portion 224 (244) of the uncoated portion 222 (242) of the wound electrode body 200 and the electrode terminal 420 (440), and VI in FIG. It is -VI sectional drawing.
- the wound electrode body 200 is attached to the electrode terminals 420 and 440 fixed to the lid body 340 in a state where the wound electrode body 200 is flatly pushed and bent.
- the wound electrode body 200 is accommodated in a flat internal space of the container body 320 as shown in FIG.
- the container body 320 is closed by the lid 340 after the wound electrode body 200 is accommodated.
- the joint 322 (see FIG. 1) between the lid 340 and the container main body 320 is welded and sealed, for example, by laser welding.
- the wound electrode body 200 is positioned in the battery case 300 by the electrode terminals 420 and 440 fixed to the lid 340 (battery case 300).
- an electrolytic solution is injected into the battery case 300 from a liquid injection hole 350 provided in the lid 340.
- a so-called non-aqueous electrolytic solution that does not use water as a solvent is used.
- an electrolytic solution in which LiPF 6 is contained at a concentration of about 1 mol / liter in a mixed solvent of ethylene carbonate and diethyl carbonate (for example, a mixed solvent having a volume ratio of about 1: 1) is used. Yes.
- a metal sealing cap 352 is attached (for example, welded) to the liquid injection hole 350 to seal the battery case 300.
- the electrolytic solution is not limited to the electrolytic solution exemplified here.
- non-aqueous electrolytes conventionally used for lithium ion secondary batteries can be used as appropriate.
- the positive electrode active material layer 223 has minute gaps 225 that should also be referred to as cavities, for example, between the positive electrode active material particles 610 and the conductive material 620 (see FIG. 4).
- An electrolytic solution (not shown) can penetrate into the minute gaps of the positive electrode active material layer 223.
- the negative electrode active material layer 243 has minute gaps 245 that should also be referred to as cavities, for example, between the negative electrode active material particles 710 (see FIG. 5).
- the gaps 225 and 245 are appropriately referred to as “holes”.
- the wound electrode body 200 has uncoated portions 222 and 242 spirally wound on both sides along the winding axis WL.
- the electrolytic solution can permeate from the gaps between the uncoated portions 222 and 242. For this reason, in the lithium ion secondary battery 100, the electrolytic solution is immersed in the positive electrode active material layer 223 and the negative electrode active material layer 243.
- the flat internal space of the battery case 300 is slightly wider than the wound electrode body 200 deformed flat.
- gaps 310 and 312 are provided between the wound electrode body 200 and the battery case 300.
- the gaps 310 and 312 serve as a gas escape path.
- the abnormally generated gas moves toward the safety valve 360 through the gaps 310 and 312 between the wound electrode body 200 and the battery case 300 on both sides of the wound electrode body 200, and from the safety valve 360 to the battery case 300. Exhausted outside.
- the positive electrode current collector 221 and the negative electrode current collector 241 are electrically connected to an external device through electrode terminals 420 and 440 that penetrate the battery case 300.
- the operation of the lithium ion secondary battery 100 during charging and discharging will be described.
- FIG. 7 schematically shows the state of the lithium ion secondary battery 100 during charging.
- the electrode terminals 420 and 440 (see FIG. 1) of the lithium ion secondary battery 100 are connected to the charger 290. Due to the action of the charger 290, lithium ions (Li) are released from the positive electrode active material in the positive electrode active material layer 223 to the electrolytic solution 280 during charging. In addition, charges are released from the positive electrode active material layer 223. The discharged electric charge is sent to the positive electrode current collector 221 through a conductive material (not shown), and further sent to the negative electrode sheet 240 through the charger 290. In the negative electrode sheet 240, electric charges are stored, and lithium ions (Li) in the electrolytic solution 280 are absorbed and stored in the negative electrode active material in the negative electrode active material layer 243.
- FIG. 8 schematically shows a state of the lithium ion secondary battery 100 during discharging.
- charges are sent from the negative electrode sheet 240 to the positive electrode sheet 220, and lithium ions stored in the negative electrode active material layer 243 are released to the electrolyte solution 280.
- lithium ions in the electrolytic solution 280 are taken into the positive electrode active material in the positive electrode active material layer 223.
- lithium ions pass between the positive electrode active material layer 223 and the negative electrode active material layer 243 through the electrolytic solution 280.
- electric charge is sent from the positive electrode active material to the positive electrode current collector 221 through the conductive material.
- the charge is returned from the positive electrode current collector 221 to the positive electrode active material through the conductive material.
- the above shows an example of a lithium ion secondary battery.
- the lithium ion secondary battery is not limited to the above form.
- an electrode sheet in which an electrode mixture is applied to a metal foil is used in various other battery forms.
- a cylindrical battery or a laminate battery is known as another battery type.
- a cylindrical battery is a battery in which a wound electrode body is accommodated in a cylindrical battery case.
- a laminate type battery is a battery in which a positive electrode sheet and a negative electrode sheet are stacked with a separator interposed therebetween.
- FIG. 9 shows a lithium ion secondary battery 100A as the proposed nonaqueous secondary battery.
- FIG. 10 is a cross-sectional view showing a laminated structure of the positive electrode sheet 220 and the negative electrode sheet 240A of the wound electrode body 200A.
- FIG. 11 is a cross-sectional view schematically showing the structure of the lithium ion secondary battery 100A.
- the lithium ion secondary battery 100A includes a negative electrode current collector 241A and a negative electrode active material that is held by the negative electrode current collector 241A and arranged to cover the positive electrode active material layer 223.
- Layer 243A In addition, separators 262 and 264 are interposed between the positive electrode active material layer 223 and the negative electrode active material layer 243A.
- the negative electrode active material layer 243A of the lithium ion secondary battery 100A includes natural graphite and artificial graphite as negative electrode active material particles. Further, as shown in FIGS. 10 and 11, the negative electrode active material layer 243A has a portion A1 facing the positive electrode active material layer 223 and portions A2 and A3 not facing the positive electrode active material layer 223. is doing. In the part A1 of the negative electrode active material layer 243A facing the positive electrode active material layer 223, the ratio of natural graphite is larger than in the parts A2 and A3 not facing the positive electrode active material layer 223. Furthermore, in the portions A2 and A3 that do not face the positive electrode active material layer 223, the ratio of artificial graphite is larger than the portion A1 that faces the positive electrode active material layer 223.
- the present inventor found that the proportion of natural graphite in the portion A1 of the negative electrode active material layer 243A facing the positive electrode active material layer 223 is larger than that of the portions A2 and A3 not facing the positive electrode active material layer 223. Furthermore, in the portions A2 and A3 that do not face the positive electrode active material layer 223, the reaction resistance (battery resistance) is increased by increasing the proportion of artificial graphite compared to the portion A1 that faces the positive electrode active material layer 223. It was found that the capacity retention rate can be kept high while keeping the value low.
- Natural graphite is a graphite material graphitized over many years in nature.
- artificial graphite is a graphite material graphitized by industrial production.
- These graphite materials have a layer structure in which carbon hexagonal mesh planes are overlapped so as to form a plurality of layers. In this case, at the time of charging, lithium ions penetrate from the edge part of the graphite material (the edge part of the layer) into the interlayer of the graphite material and spread between the layers.
- scaly graphite particles also referred to as scaly graphite
- the natural graphite may be covered at least partially with an amorphous carbon film, for example.
- the amorphous carbon film is a film made of an amorphous carbon material.
- natural graphite that is at least partially covered with an amorphous carbon film can be obtained by mixing pitch with natural graphite as a core and baking it.
- the weight ratio X of the amorphous carbon film is preferably about 0.01 ⁇ X ⁇ 0.10.
- the weight ratio X of the amorphous carbon film is more preferably 0.02 ⁇ X, and the upper limit is more preferably X ⁇ 0.08, and further preferably X ⁇ 0.06. .
- natural graphite has a so-called R value in Raman spectroscopy of 0.2 to 0.6
- artificial graphite has an R value of 0.2 or less.
- R value is referred to as an R value which is a ratio of two Raman spectral bands, a G band (1580 cm ⁇ 1 ) derived from a graphite structure, and a D band (1360 cm ⁇ 1 ) resulting from a structural disorder (Disorder).
- It is an intensity ratio (R I 1360 / I 1580 ).
- a device for obtaining a Raman spectral band for example, a Nicolet dispersion type laser Raman device manufactured by Thermo Fisher, Inc. can be used.
- the R value of natural graphite By setting the R value of natural graphite to 0.2 to 0.6 and the R value of artificial graphite to 0.2 or less, it is preferable to select artificial graphite having a more complete graphite structure than natural graphite.
- the natural graphite may have an R value of 0.22 or more.
- Artificial graphite may have an R value of less than 0.18. Thereby, the difference of R value can be produced more clearly between natural graphite and artificial graphite.
- the R value may be evaluated by extracting at least 100 particles and averaging them.
- the method for forming the negative electrode active material layer 243A includes, for example, the following steps A to D.
- a first mixture is prepared.
- a 1st mixture is a mixture applied to the site
- a second mixture is prepared.
- a 2nd mixture is a mixture applied to the site
- Step C the first mixture prepared in Step A is applied to a portion corresponding to the portion A1 facing the positive electrode active material layer 223 in the negative electrode current collector 241A.
- Step D the second mixture prepared in Step B is applied to portions corresponding to the portions A2 and A3 that do not face the positive electrode active material layer 223 in the negative electrode current collector 241A.
- a paste obtained by mixing natural graphite, a binder, and a solvent may be prepared.
- a paste containing natural graphite without artificial graphite can be obtained as negative electrode active material particles.
- a paste obtained by mixing artificial graphite, a binder, and a solvent may be prepared.
- a paste containing artificial graphite without natural graphite can be obtained as negative electrode active material particles.
- FIG. 12 is a diagram illustrating a process of forming the negative electrode active material layer 243A.
- the negative electrode active material layer 243A is formed by applying the first mixture prepared in Step A and the second mixture prepared in Step B to a predetermined portion of the negative electrode current collector 241A. It is formed by pressing after drying.
- a drying furnace 16 for drying the mixture applied to the negative electrode current collector 241A.
- the travel route 12 is a route on which the negative electrode current collector 241A travels.
- a plurality of guides 12b are arranged on the traveling route 12 along a predetermined route for traveling the negative electrode current collector 241A.
- a supply unit 32 that supplies the negative electrode current collector 241 ⁇ / b> A is provided at the start end of the travel path 12.
- the supply unit 32 is provided with a negative electrode current collector 241A that is previously wound around a winding core 32a.
- An appropriate amount of the negative electrode current collector 241A is appropriately supplied from the supply unit 32 to the travel path 12.
- a collection unit 34 that collects the negative electrode current collector 241A is provided at the end of the traveling path 12.
- the collection unit 34 winds the negative electrode current collector 241A that has been subjected to a predetermined process in the travel path 12 around the winding core 34a.
- the collection unit 34 is provided with, for example, a control unit 34b and a motor 34c.
- the control unit 34b is preset with a program for controlling the rotation of the winding core 34a of the collection unit 34.
- the motor 34c is an actuator that rotationally drives the winding core 34a, and is driven according to a program set in the control unit 34b.
- An electrode material coating device 14 and a drying furnace 16 are sequentially arranged on the traveling path 12.
- Electrode material application device 14 (application process) ⁇
- the wound electrode body 200 in the wound electrode body 200 (see FIG. 10 and FIG. 11) that is subsequently created, a portion A1 that faces the positive electrode active material layer 223, and portions A2 and A3 that do not face the positive electrode active material layer 223,
- the configuration of the negative electrode active material particles included in the negative electrode active material layer 243 is different.
- the electrode material coating apparatus 14 mixes a mixture in which the configuration of the negative electrode active material particles is different between the portion A1 facing the positive electrode active material layer 223 and the portions A2 and A3 not facing the positive electrode active material layer 223. Apply.
- “to make the configuration of the negative electrode active material particles different” means a case where the configuration (material and content ratio) of the negative electrode active material particles is substantially different.
- different negative electrode active material particles are used in the portion A1 facing the positive electrode active material layer 223 and the portions A2 and A3 not facing the positive electrode active material layer 223. It is included.
- two or more types of negative electrode active materials are included in a part A1 facing the positive electrode active material layer 223 and parts A2 and A3 not facing the positive electrode active material layer 223. This includes cases where particles are included and the proportions are different.
- the degree to which the content ratio of each negative electrode active material particle is slightly different due to manufacturing errors is substantially equal here. Shall be the same.
- the configuration of the negative electrode active material particles is substantially the same here for the extent that the content ratio of each negative electrode active material particle is slightly different locally in a very small region of the negative electrode active material layer 243A. .
- the electrode material coating device 14 includes flow paths 41 and 42, filters 43 and 44, and a coating unit 45, as shown in FIG.
- the electrode material application device 14 is configured to apply the mixture to the negative electrode current collector 241 that travels on the back roll 46 disposed in the travel path 12.
- the electrode material application device 14 further includes tanks 47 and 48 and pumps 49 and 50.
- the tanks 47 and 48 are containers storing different mixtures.
- the pumps 49 and 50 are devices that send the mixture from the tanks 47 and 48 to the flow paths 41 and 42, respectively.
- the flow paths 41 and 42 are flow paths through which a slurry in which negative electrode active material particles are dispersed in a solvent can flow.
- the flow paths 41 and 42 reach the application unit 45 from the tanks 47 and 48, respectively.
- the filters 43 and 44 are disposed in the flow paths 41 and 42.
- the tanks 47 and 48 are used to form a first mixture applied to a portion A1 facing the positive electrode active material layer 223 and a negative electrode active material layer having a relatively low equilibrium potential. Two combinations are prepared.
- the first mixture and the second mixture are different in the type of negative electrode active material particles contained in the solvent.
- it is preferable that a 1st mixture and a 2nd mixture do not mix easily. For example, it is difficult to mix the first mixture and the second mixture by appropriately adjusting the solid content concentration of the first mixture and the solid content concentration of the second mixture.
- FIG. 13 is a diagram illustrating an example of a die used to form the negative electrode active material layer 243A.
- a die 60 having a horizontally long discharge port 62 is used for the application unit 45.
- the discharge port 62 of the die 60 is divided into an intermediate portion 62a and both side portions 62b1 and 62b2.
- An intermediate portion 62a of the discharge port 62 communicates with the flow path 41 to which the first mixture is supplied. Further, both side portions 62b1 and 62b2 of the discharge port 62 communicate with the flow path 42 to which the second mixture is supplied. The middle portion 62a of the discharge port 62 discharges the first mixture. Further, both side portions 62b1 and 62b2 of the discharge port 62 discharge the second mixture.
- the intermediate portion 62a of the discharge port 62 of the die 60 is aligned with a portion A1 of the negative electrode current collector 241A that faces the positive electrode active material layer 223. Further, both side portions 62b1 and 62b2 of the discharge port 62 of the die 60 are aligned with portions A2 and A3 of the negative electrode current collector 241A that do not face the positive electrode active material layer 223.
- the first mixture is applied to a portion A1 of the negative electrode current collector 241A that faces the positive electrode active material layer 223.
- the second mixture is applied to portions A2 and A3 of the negative electrode current collector 241A that do not face the positive electrode active material layer 223.
- the negative electrode current collector 241A coated with the first mixture and the second mixture is supplied to the drying furnace 16 (see FIG. 12).
- a negative electrode active material layer 243A having a different configuration of the negative electrode active material particles is formed between the portion A1 facing the positive electrode active material layer 223 and the portions A2 and A3 not facing the positive electrode active material layer 223.
- the first mixture a mixture using natural graphite as the negative electrode active material particles (or a ratio of natural graphite compared to artificial graphite) is prepared.
- a mixture using artificial graphite as the negative electrode active material particles (or a ratio of artificial graphite larger than that of natural graphite) is prepared.
- the portion A1 of the negative electrode current collector 241A facing the positive electrode active material layer 223 has a large proportion of natural graphite, and the portion A2 of the negative electrode current collector 241A not facing the positive electrode active material layer 223.
- the negative electrode active material layer 243A having a large proportion of artificial graphite can be formed.
- the negative electrode active material at the portion A1 facing the positive electrode active material layer 223 and the portions A2 and A3 not facing the positive electrode active material layer 223 can be appropriately changed.
- the inventor appropriately differs the configuration of the negative electrode active material particles contained in the negative electrode active material layer 243A between the portion A1 facing the positive electrode active material layer 223 and the portions A2 and A3 not facing the positive electrode active material layer 223.
- the ratio of natural graphite is increased at the portion A1 facing the positive electrode active material layer 223, and further, the artificial graphite at the portions A2 and A3 not facing the positive electrode active material layer 223. It was found that the capacity retention rate can be kept high while the reaction resistance (battery resistance) is kept low by increasing the ratio.
- the configuration of the negative electrode active material particles included in the negative electrode active material layer 243A includes the portion A1 facing the positive electrode active material layer 223 and the portions A2 and A3 not facing the positive electrode active material layer 223.
- the evaluation cells were made appropriately different. And about each evaluation cell, reaction resistance and a capacity
- the evaluation cell was a so-called cylindrical 18650 type cell (not shown). Samples 1 to 5 having different negative electrode active material layer structures were prepared as evaluation cells.
- a positive electrode mixture was prepared.
- the positive electrode mixture includes a ternary lithium transition metal oxide (LiNi 1/3 Co 1/3 Mn 1/3 O 2 ) as a positive electrode active material, acetylene black (AB) as a conductive material, and polyfluoride as a binder. Vinylidene chloride (PVDF) was used.
- a positive electrode mixture was prepared by mixing these positive electrode active material, conductive material, and binder with ion-exchanged water.
- the positive electrode mixture was applied to both sides of the positive electrode current collector and dried.
- an aluminum foil (thickness 15 ⁇ m) as a positive electrode current collector was used.
- the positive electrode sheet was dried and then rolled with a roller press to a thickness of 110 ⁇ m.
- the amount of the positive electrode mixture applied to the positive electrode current collector was set so that the positive electrode active material layer was 25 mg / cm 2 per unit area of the positive electrode current collector after the positive electrode mixture was dried.
- ⁇ Negative electrode of evaluation cell ⁇ As the negative electrode mixture, negative electrode active material particles and carboxymethyl cellulose (CMC) and a binder were used as thickeners, respectively.
- CMC carboxymethyl cellulose
- a binder styrene-butadiene rubber
- SBR styrene-butadiene rubber
- a negative electrode mixture was prepared by mixing these negative electrode active material particles, CMC, and SBR with ion-exchanged water. Next, the negative electrode mixture was applied to both sides of the negative electrode current collector and dried. Here, a copper foil (thickness 10 ⁇ m) as a negative electrode current collector was used. This produced the negative electrode (negative electrode sheet) provided with the negative electrode active material layer on both surfaces of the negative electrode current collector. The negative electrode sheet was dried and then rolled with a roller press to a thickness of 100 ⁇ m.
- the thickness of the negative electrode active material layer formed on both surfaces of the negative electrode current collector was set to 45 ⁇ m.
- the amount of the negative electrode mixture applied to the negative electrode current collector was set so that the negative electrode active material layer was 13 mg / cm 2 per unit area of the negative electrode current collector after the negative electrode mixture was dried.
- a test 18650 type cell (lithium ion battery) was constructed using the negative electrode prepared above, the positive electrode, and the separator.
- a cylindrical wound electrode body was manufactured by laminating and winding a positive electrode sheet and a negative electrode sheet with a separator interposed. Then, the wound electrode body was housed in a cylindrical battery case, and a nonaqueous electrolyte was injected and sealed to construct an evaluation cell.
- evaluation cells having different configurations of the negative electrode active material particles were prepared in the part A1 of the negative electrode active material layer facing the positive electrode active material layer 223 and the parts A2 and A3 not facing the positive electrode active material layer 223. .
- the evaluation cell was subjected to predetermined conditioning, and then the reaction resistance at ⁇ 30 ° C. and the capacity retention ratio after storage (capacity retention ratio after storage in a predetermined high temperature environment for a predetermined time) were evaluated.
- conditioning is performed by the following procedures 1 and 2.
- Procedure 1 After reaching 4.1 V with a constant current charge of 1 C, pause for 5 minutes.
- Procedure 2 After Procedure 1, charge for 1.5 hours by constant voltage charging and rest for 5 minutes. In such conditioning, a required reaction occurs due to initial charging, and gas is generated. Moreover, a required film formation is formed on the negative electrode active material layer or the like.
- the rated capacity is measured for the evaluation cell.
- the rated capacity is measured by the following procedures 1 to 3.
- Procedure 1 After reaching 3.0V by constant current discharge of 1C, discharge by constant voltage discharge for 2 hours, and then rest for 10 seconds.
- Procedure 2 After reaching 4.1 V by constant current charging at 1 C, charge for 2.5 hours by constant voltage charging, and then rest for 10 seconds.
- Procedure 3 After reaching 3.0 V by constant current discharge of 0.5 C, discharge at constant voltage discharge for 2 hours, and then stop for 10 seconds.
- the discharge capacity (CCCV discharge capacity) in the discharge from the constant current discharge to the constant voltage discharge in the procedure 3 is defined as “rated capacity”.
- the SOC adjustment is performed by the following procedures 1 and 2.
- the SOC adjustment may be performed after the conditioning process and the measurement of the rated capacity.
- SOC adjustment is performed in a temperature environment of 25 ° C.
- Procedure 1 Charging at a constant current of 3V to 1C to obtain a charged state (SOC 60%) of about 60% of the rated capacity.
- Procedure 2 After procedure 1, charge at constant voltage for 2.5 hours. Thereby, the cell for evaluation can be adjusted to a predetermined charge state.
- SOC is adjusted to 60%
- it can be adjusted to an arbitrary charged state by changing the charged state in procedure 1. For example, when adjusting to SOC 90%, in the procedure 1, the evaluation cell may be in a charged state (SOC 90%) of 90% of the rated capacity.
- the initial capacity is measured by charging an evaluation cell adjusted to a predetermined charge state at a constant current of 1 C until the voltage between the terminals reaches 4.1 V under a temperature condition of 25 ° C.
- the battery was charged at a constant voltage until the charging time reached 2.5 hours (CC-CV charging).
- CC-CV charging CC-CV charging
- the discharge capacity at this time was defined as the initial capacity Q1 [Ah] of each battery.
- the initial capacity was measured after adjusting the evaluation cell to SOC 90%.
- the reaction resistance is a reaction resistance measured by an AC impedance measurement method.
- FIG. 14 is a diagram showing a typical example of a Cole-Cole plot (Nyquist plot) in the AC impedance measurement method.
- the DC resistance (Rsol) and the reaction resistance (Rct) can be calculated based on the Cole-Cole plot obtained by equivalent circuit fitting in the AC impedance measurement method.
- the reaction resistance (Rct) can be obtained by the following equation.
- Rct (Rsol + Rct) ⁇ Rsol;
- Such measurement and calculation of direct current resistance (Rsol) and reaction resistance (Rct) can be carried out using a commercially available apparatus programmed in advance.
- An example of such an apparatus is an electrochemical impedance measuring apparatus manufactured by Solartron.
- complex impedance measurement is performed in a frequency range of 10 ⁇ 3 to 10 4 Hz based on an evaluation cell adjusted to SOC 40% (charged state of about 40% of the rated capacity). I did it.
- the reaction resistance (Rct) obtained by the equivalent circuit fitting of the Nyquist plot was defined as “reaction resistance at ⁇ 30 ° C.”.
- Capacity maintenance rate (capacity maintenance rate after storage) is obtained by storing the evaluation cell adjusted to a predetermined state of charge in a predetermined environment for a predetermined time, and then discharging capacity (hereinafter referred to as “ It is calculated by the ratio (capacity after storage) / (initial capacity).
- “capacity after storage” is a discharge capacity measured based on an evaluation cell stored in a temperature environment of 60 ° C. for 30 days after adjusting to SOC 90%.
- “Capacity maintenance after storage” (capacity after storage) / (initial capacity) ⁇ 100 (%);
- the present inventor prepared natural graphite and artificial graphite as negative electrode active material particles.
- natural graphite coated with an amorphous carbon film was prepared as natural graphite.
- samples having different configurations of the negative electrode active material particles were prepared for the part A1 facing the positive electrode active material layer 223 and the parts A2 and A3 not facing the positive electrode active material layer 223.
- Table 1 and FIG. 15 show the reaction resistance (m ⁇ ) at ⁇ 30 ° C. and the capacity retention rate (%) after storage for the following samples 1 to 5.
- the reaction resistance (m ⁇ ) at ⁇ 30 ° C. is shown by a bar graph
- the capacity retention rate (%) after storage is shown by a plot of “ ⁇ ”.
- sample 4 in the negative electrode active material layer 243A (see FIG. 11), natural graphite and artificial graphite are formed in the portions A1 facing the positive electrode active material layer 223 and the portions A2 and A3 not facing the positive electrode active material layer 223.
- a mixture in which graphite was mixed at a predetermined ratio was used as negative electrode active material particles.
- natural graphite: artificial graphite 93: 7 in terms of mass ratio.
- the reaction resistance was 743 m ⁇ , and the capacity retention after storage was 79.4%.
- the reaction resistance (m ⁇ ) at ⁇ 30 ° C. can be kept low, but the capacity retention rate (%) after storage tends to be low.
- SEI solid electrolyte interface
- SEI can be formed by a reductive decomposition reaction of the electrolyte.
- Such SEI is indispensable for insertion / extraction of lithium ions in graphite.
- SEI is generated by a reductive decomposition reaction of the electrolytic solution, electric charge is consumed for the reaction. This causes irreversible capacity.
- the portions A2 and A3 that do not face the positive electrode active material layer 223 are portions that do not contribute much to the reaction during charge and discharge at a high rate.
- the reaction resistance of the lithium ion secondary battery increases and the capacity retention rate decreases.
- the present inventor generates excessive SEI in the portions A2 and A3 not facing the positive electrode active material layer 223 by using artificial graphite in the portions A2 and A3 not facing the positive electrode active material layer 223. It is believed that lithium ions can be prevented while being suppressed.
- the portion A1 facing the positive electrode active material layer 223 has a large proportion of natural graphite, and the portion A2 not facing the positive electrode active material layer 223.
- A3 has a large proportion of artificial graphite, the battery resistance in a low temperature environment can be kept low, and the capacity retention rate after storage in a high temperature environment can be kept high.
- natural graphite is used as the negative electrode active material particles in the portion A1 facing the positive electrode active material layer 223, and the positive electrode active material layer 223 is formed.
- Artificial graphite was used as negative electrode active material particles in the portions A2 and A3 which were not opposed to each other.
- natural graphite is used as the negative electrode active material particles in the portion A1 facing the positive electrode active material layer 223, and artificial graphite is used as the negative electrode active material particles in the portions A2 and A3 not facing the positive electrode active material layer 223. It was. Further, as the negative electrode active material particles, a mixture of natural graphite and artificial graphite may be used, respectively.
- the proportion of natural graphite is preferably increased in the portion A1 facing the positive electrode active material layer 223, and the proportion of artificial graphite is increased in the portions A2 and A3 not facing the positive electrode active material layer 223.
- materials other than natural graphite and artificial graphite may be mixed a little to such an extent that the said battery performance is acquired.
- the negative electrode active material layer 243A (see FIG. 11) has a natural graphite ratio in the portion A1 facing the positive electrode active material layer 223 as compared with the portions A2 and A3 not facing the positive electrode active material layer 223.
- a battery in a low temperature environment is obtained by increasing the proportion of artificial graphite in the portions A2 and A3 that are large and do not face the positive electrode active material layer 223 as compared with the portion A1 that faces the positive electrode active material layer 223. There was a tendency to keep resistance low and to maintain a high capacity retention rate after storage in a high temperature environment.
- the weight ratio of natural graphite of natural graphite and artificial graphite is preferably 90% or more.
- the effect which made the ratio of natural graphite high can be appropriately acquired in site
- the effect of increasing the ratio of natural graphite may be appropriately obtained in the portion A1 of the negative electrode active material layer 243A facing the positive electrode active material layer 223. Therefore, in the portion A1 of the negative electrode active material layer 243A facing the positive electrode active material layer 223, for example, the natural graphite and artificial graphite may have a weight ratio of natural graphite of 95% or more, and such a ratio. May be about 90% or about 85%.
- the weight ratio of artificial graphite of natural graphite and artificial graphite is preferably 90% or more. Thereby, the effect which made the ratio of artificial graphite high can be appropriately acquired in site
- the effect of increasing the ratio of artificial graphite may be appropriately obtained in the portions A2 and A3 that do not face the positive electrode active material layer 223 in the negative electrode active material layer 243A. Therefore, in the portions A2 and A3 of the negative electrode active material layer 243A that do not face the positive electrode active material layer 223, for example, the weight ratio of the artificial graphite of natural graphite and artificial graphite is preferably 95% or more. Such a ratio may be about 90% or about 85%.
- natural graphite has a so-called R value in Raman spectroscopy of 0.2 to 0.6
- artificial graphite has an R value of 0.2 or less.
- the R value of natural graphite By setting the R value of natural graphite to 0.2 to 0.6 and the R value of artificial graphite to 0.2 or less, it is preferable to select artificial graphite having a more complete graphite structure than natural graphite.
- the natural graphite may have an R value of 0.22 or more.
- Artificial graphite may have an R value of less than 0.18. Thereby, the difference of R value can be produced more clearly between natural graphite and artificial graphite.
- the R value may be evaluated by extracting at least 100 particles and averaging them.
- the average R value (Ra) of the negative electrode active material particles used in the portion A1 facing the positive electrode active material layer 223 and the positive electrode active material layer 223 are opposed.
- the ratio (Ra / Rb) to the average R value (Rb) of the negative electrode active material particles used in the portions A2 and A3 that are not present may be (Ra / Rb) ⁇ 1.2. More preferably, (Ra / Rb) ⁇ 1.5, and more preferably (Ra / Rb) ⁇ 2.0.
- the negative electrode active material particles used in the portion A1 of the negative electrode active material layer 243A facing the positive electrode active material layer 223 and the positive electrode active material layer 223 are opposed to each other.
- R value there is a clear difference in R value between the negative electrode active material particles used in the portions A2 and A3 that are not present.
- the average R value (Ra) of the negative electrode active material particles used in the portion A1 facing the positive electrode active material layer 223 is opposite to the positive electrode active material layer 223 in the negative electrode active material layer 243A. At least 100 or more negative electrode active material particles are extracted from the negative electrode active material particles contained in the portion A1, and the R value is obtained for each of the negative electrode active material particles. Further, the average R value (Rb) of the negative electrode active material particles used in the portions A2 and A3 not facing the positive electrode active material layer 223 is also opposed to the positive electrode active material layer 223 in the negative electrode active material layer 243A. In the portions A2 and A3 that are not formed, the negative electrode active material particles are extracted to obtain R values, respectively, and can be evaluated by their arithmetic average values.
- the extraction of the negative electrode active material particles from the negative electrode active material layer 243A is performed by peeling the negative electrode active material layer 243A from the negative electrode current collector 241A by applying ultrasonic vibration to the negative electrode sheet 240A, for example. It is good to heat 243A and to burn off a binder and a thickener. Thereby, the negative electrode active material particles contained in the negative electrode active material layer 243A can be extracted.
- the lithium ion secondary battery according to one embodiment of the present invention has been described above.
- the present invention can be further devised.
- the negative electrode active material layer 243A wants to reduce the resistance to movement (diffusion) of lithium ions. For this reason, it is desirable to reduce the amount of the binder contained in the negative electrode active material layer 243A.
- the amount of the binder contained in the negative electrode active material layer 243A is reduced, an event in which the negative electrode active material layer 243A is peeled off from the negative electrode current collector 241A may occur in use where charge / discharge at a high rate is repeated.
- charge transfer between the negative electrode active material layer 243A and the negative electrode current collector 241A is hindered, which may increase battery resistance.
- the portion A1 facing the positive electrode active material layer 223 is compared with the portions A2 and A3 not facing the positive electrode active material layer 223.
- the ratio of natural graphite is large.
- the ratio of artificial graphite is larger than the portion A1 that faces the positive electrode active material layer 223.
- the portions A2 and A3 of the negative electrode active material layer 243A that do not face the positive electrode active material layer 223 have a particularly small contribution to output characteristics, particularly in charge and discharge at a high rate. Therefore, the binder content may be increased in the portions A2 and A3 of the negative electrode active material layer 243A that do not face the positive electrode active material layer 223. Accordingly, the binding between the negative electrode active material layer 243A and the negative electrode current collector 241A becomes strong at the portions A2 and A3 that do not face the positive electrode active material layer 223. Then, the negative electrode active material layer 243A can be hardly peeled off from the negative electrode current collector 241A without substantially affecting the occlusion of lithium ions in the portion A1 facing the positive electrode active material layer 223.
- the negative electrode active material layer 243A (see FIG. 11) is a portion where the ratio of natural graphite is large at the portion A1 facing the positive electrode active material layer 223 and is not facing the positive electrode active material layer 223.
- the portions A2 and A3 of the negative electrode active material layer 243A that do not face the positive electrode active material layer 223 are further compared with the portion A1 of the negative electrode active material layer 243A that faces the positive electrode active material layer 223.
- the binder content should be increased. Accordingly, the negative electrode active material layer 243A can be prevented from being peeled from the negative electrode current collector 241A, and the durability performance of the lithium ion secondary battery 100A can be improved.
- the inventor pays attention to the tap density when natural graphite or artificial graphite is used for the negative electrode active material particles.
- the present inventor proposes that the 150-time tap density of the negative electrode active material particle is 1 g / cm 3 or more.
- the 150-times tap density reduces the apparent volume of the negative electrode active material particles by putting negative electrode active material particles into a graduated cylinder and mechanically hitting the graduated cylinder 150 times with a tapping device.
- FIG. 16 shows the relationship between the 150-time tap density and the peel strength for the negative electrode active material particles.
- FIG. 17 is a diagram showing a 90-degree peel adhesion strength test method. Here, the peel strength was measured according to a 90 degree peel adhesion strength test method (JIS K 6854-1).
- a Nitto Denko adhesive tape 105 (No. 3303N) is attached to the negative electrode active material layer 164 on one side of the negative electrode sheet 166, and the size is 15 mm wide ⁇ 120 mm long. Cut it out.
- the adhesive tape 105 is peeled off by 40 mm from one end.
- a Nitto Denko double-sided tape (No. 501F) is applied to the stage 115.
- the sample 120 is stuck on the double-sided tape 110 with the adhesive tape 105 facing down.
- the 40 mm portion from which the sample 120 has been peeled off is fixed to the chuck 125.
- the chuck 125 is pulled at 90 ° with respect to the stage 115, and the tensile load when the negative electrode active material layer 164 is peeled off from the negative electrode current collector 162 is measured.
- a Minebea universal testing machine was used to pull the chuck 125. The pulling speed was 20 m / min.
- the peel strength N / m was determined by dividing the obtained tensile load (N) by the width of the sample 120 (15 mm).
- the negative electrode active material layer 243A shown in FIG. 9 and FIG. 10 when the 150-time tap density of the negative electrode active material particles is about 1 g / cm 3 or more, the peel strength is high. Obviously, in the above-described lithium ion secondary battery 100A, the negative electrode active material layer 243A has a 150-time tap density of about 1 g / cm 3 or more, more preferably 1.08 g / cm 3 or more, and even more preferably 1.10 g. It is preferable to use negative electrode active material particles that are / cm 3 or more. Thereby, it is possible to ensure an appropriate peel strength for the negative electrode active material layer 243A.
- the lithium ion secondary battery according to one embodiment of the present invention has been described above, the lithium ion secondary battery according to the present invention is not limited to any of the above-described embodiments, and various modifications are possible. .
- the lithium ion secondary battery disclosed herein can keep the reaction resistance low even in a low temperature environment of about ⁇ 30 ° C., and is a non-aqueous secondary battery such as a lithium ion secondary battery that exhibits high performance in a low temperature environment.
- a secondary battery can be provided.
- the lithium ion secondary battery can maintain a high capacity retention rate after storage even in a high temperature environment of about 60 ° C. Therefore, as shown in FIG. 18, the lithium ion secondary battery 100A is particularly suitable as a vehicle driving battery that requires low resistance and high capacity in various temperature environments.
- the vehicle driving battery 10 may be in the form of an assembled battery formed by connecting a plurality of the lithium ion secondary batteries 100A in series.
- the vehicle 1000 having such a vehicle driving battery as a power source typically includes an automobile, particularly an automobile having an electric motor such as a hybrid automobile or an electric automobile.
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Abstract
Description
図1は、リチウムイオン二次電池100を示している。このリチウムイオン二次電池100は、図1に示すように、捲回電極体200と電池ケース300とを備えている。図2は、捲回電極体200を示す図である。図3は、図2中のIII-III断面を示している。
正極シート220は、帯状の正極集電体221と正極活物質層223とを備えている。正極集電体221には、正極に適する金属箔が好適に使用され得る。正極集電体221には、例えば、所定の幅を有し、厚さが凡そ15μmの帯状のアルミニウム箔を用いることができる。正極集電体221の幅方向片側の縁部に沿って未塗工部222が設定されている。図示例では、正極活物質層223は、図3に示すように、正極集電体221に設定された未塗工部222を除いて、正極集電体221の両面に保持されている。正極活物質層223には、正極活物質が含まれている。正極活物質層223は、正極活物質を含む正極合剤を正極集電体221に塗工することによって形成されている。
ここで、図4は、正極シート220の断面図である。なお、図4において、正極活物質層223の構造が明確になるように、正極活物質層223中の正極活物質粒子610と導電材620とバインダ630とを大きく模式的に表している。正極活物質層223には、図4に示すように、正極活物質粒子610と導電材620とバインダ630が含まれている。
導電材620としては、例えば、カーボン粉末、カーボンファイバーなどのカーボン材料が例示される。導電材620としては、このような導電材から選択される一種を単独で用いてもよく二種以上を併用してもよい。カーボン粉末としては、種々のカーボンブラック(例えば、アセチレンブラック、オイルファーネスブラック、黒鉛化カーボンブラック、カーボンブラック、黒鉛、ケッチェンブラック)、グラファイト粉末などのカーボン粉末を用いることができる。
また、バインダ630は、正極活物質層223に含まれる正極活物質粒子610と導電材620の各粒子を結着させたり、これらの粒子と正極集電体221とを結着させたりする。かかるバインダ630としては、使用する溶媒に溶解または分散可能なポリマーを用いることができる。例えば、水性溶媒を用いた正極合剤組成物においては、セルロース系ポリマー(カルボキシメチルセルロース(CMC)、ヒドロキシプロピルメチルセルロース(HPMC)など)、フッ素系樹脂(例えば、ポリビニルアルコール(PVA)、ポリテトラフルオロエチレン(PTFE)、テトラフルオロエチレン-ヘキサフルオロプロピレン共重合体(FEP)など)、ゴム類(酢酸ビニル共重合体、スチレンブタジエン共重合体(SBR)、アクリル酸変性SBR樹脂(SBR系ラテックス)など)などの水溶性または水分散性ポリマーを好ましく採用することができる。また、非水溶媒を用いた正極合剤組成物においては、ポリマー(ポリフッ化ビニリデン(PVDF)、ポリ塩化ビニリデン(PVDC)、ポリアクリルニトリル(PAN)など)を好ましく採用することができる。
正極活物質層223は、例えば、上述した正極活物質粒子610と導電材620を溶媒にペースト状(スラリ状)に混ぜ合わせた正極合剤を作製し、正極集電体221に塗布し、乾燥させ、圧延することによって形成されている。この際、正極合剤の溶媒としては、水性溶媒および非水溶媒の何れも使用可能である。非水溶媒の好適な例としてN-メチル-2-ピロリドン(NMP)が挙げられる。上記バインダ630として例示したポリマー材料は、バインダとしての機能の他に、正極合剤の増粘剤その他の添加剤としての機能を発揮する目的で使用されることもあり得る。
負極シート240は、図2に示すように、帯状の負極集電体241と、負極活物質層243とを備えている。負極集電体241には、負極に適する金属箔が好適に使用され得る。この負極集電体241には、所定の幅を有し、厚さが凡そ10μmの帯状の銅箔が用いられている。負極集電体241の幅方向片側には、縁部に沿って未塗工部242が設定されている。負極活物質層243は、負極集電体241に設定された未塗工部242を除いて、負極集電体241の両面に形成されている。負極活物質層243は、負極集電体241に保持され、少なくとも負極活物質が含まれている。負極活物質層243は、負極活物質を含む負極合剤が負極集電体241に塗工されている。
図5は、リチウムイオン二次電池100の負極シート240の断面図である。負極活物質層243には、図5に示すように、負極活物質粒子710、増粘剤(図示省略)、バインダ730などが含まれている。図5では、負極活物質層243の構造が明確になるように、負極活物質層243中の負極活物質粒子710とバインダ730とを大きく模式的に表している。
負極活物質粒子710としては、負極活物質として従来からリチウムイオン二次電池に用いられる材料の一種または二種以上を特に限定なく使用することができる。例えば、少なくとも一部にグラファイト構造(層状構造)を含む粒子状の炭素材料(カーボン粒子)が挙げられる。より具体的には、負極活物質は、例えば、天然黒鉛、非晶質の炭素材料でコートした天然黒鉛、黒鉛質(グラファイト)、難黒鉛化炭素質(ハードカーボン)、易黒鉛化炭素質(ソフトカーボン)、または、これらを組み合わせた炭素材料でもよい。なお、ここでは、負極活物質粒子710は、いわゆる鱗片状黒鉛が用いられた場合を図示しているが、負極活物質粒子710は、図示例に限定されない。
負極活物質層243は、例えば、上述した負極活物質粒子710とバインダ730を溶媒にペースト状(スラリ状)に混ぜ合わせた負極合剤を作製し、負極集電体241に塗布し、乾燥させ、圧延することによって形成されている。この際、負極合剤の溶媒としては、水性溶媒および非水溶媒の何れも使用可能である。非水溶媒の好適な例としてN-メチル-2-ピロリドン(NMP)が挙げられる。バインダ730には、上記正極活物質層223(図4参照)のバインダ630として例示したポリマー材料を用いることができる。また、上記正極活物質層223のバインダ630として例示したポリマー材料は、バインダとしての機能の他に、正極合剤の増粘剤その他の添加剤としての機能を発揮する目的で使用されることもあり得る。
セパレータ262、264は、図1または図2に示すように、正極シート220と負極シート240とを隔てる部材である。この例では、セパレータ262、264は、微小な孔を複数有する所定幅の帯状のシート材で構成されている。セパレータ262、264には、例えば、多孔質ポリオレフィン系樹脂で構成された単層構造のセパレータ或いは積層構造のセパレータを用いることができる。この例では、図2および図3に示すように、負極活物質層243の幅b1は、正極活物質層223の幅a1よりも少し広い。さらにセパレータ262、264の幅c1、c2は、負極活物質層243の幅b1よりも少し広い(c1、c2>b1>a1)。
また、この例では、電池ケース300は、図1に示すように、いわゆる角型の電池ケースであり、容器本体320と、蓋体340とを備えている。容器本体320は、有底四角筒状を有しており、一側面(上面)が開口した扁平な箱型の容器である。蓋体340は、当該容器本体320の開口(上面の開口)に取り付けられて当該開口を塞ぐ部材である。
その後、蓋体340に設けられた注液孔350から電池ケース300内に電解液が注入される。電解液は、水を溶媒としていない、いわゆる非水電解液が用いられている。この例では、電解液は、エチレンカーボネートとジエチルカーボネートとの混合溶媒(例えば、体積比1:1程度の混合溶媒)にLiPF6を約1mol/リットルの濃度で含有させた電解液が用いられている。その後、注液孔350に金属製の封止キャップ352を取り付けて(例えば溶接して)電池ケース300を封止する。なお、電解液は、ここで例示された電解液に限定されない。例えば、従来からリチウムイオン二次電池に用いられている非水電解液は適宜に使用することができる。
ここで、正極活物質層223は、例えば、正極活物質粒子610と導電材620の粒子間などに、空洞とも称すべき微小な隙間225を有している(図4参照)。かかる正極活物質層223の微小な隙間には電解液(図示省略)が浸み込み得る。また、負極活物質層243は、例えば、負極活物質粒子710の粒子間などに、空洞とも称すべき微小な隙間245を有している(図5参照)。ここでは、かかる隙間225、245(空洞)を適宜に「空孔」と称する。また、捲回電極体200は、図2に示すように、捲回軸WLに沿った両側において、未塗工部222、242が螺旋状に巻かれている。かかる捲回軸WLに沿った両側252、254において、未塗工部222、242の隙間から、電解液が浸み込みうる。このため、リチウムイオン二次電池100の内部では、正極活物質層223と負極活物質層243に電解液が浸み渡っている。
また、この例では、当該電池ケース300の扁平な内部空間は、扁平に変形した捲回電極体200よりも少し広い。捲回電極体200の両側には、捲回電極体200と電池ケース300との間に隙間310、312が設けられている。当該隙間310、312は、ガス抜け経路になる。例えば、過充電が生じた場合などにおいて、リチウムイオン二次電池100の温度が異常に高くなると、電解液が分解されてガスが異常に発生する場合がある。この実施形態では、異常に発生したガスは、捲回電極体200の両側における捲回電極体200と電池ケース300との隙間310、312を通して安全弁360の方へ移動し、安全弁360から電池ケース300の外に排気される。
図7は、かかるリチウムイオン二次電池100の充電時の状態を模式的に示している。充電時においては、図7に示すように、リチウムイオン二次電池100の電極端子420、440(図1参照)は、充電器290に接続される。充電器290の作用によって、充電時には、正極活物質層223中の正極活物質からリチウムイオン(Li)が電解液280に放出される。また、正極活物質層223からは電荷が放出される。放出された電荷は、導電材(図示省略)を通じて正極集電体221に送られ、さらに、充電器290を通じて負極シート240へ送られる。また、負極シート240では電荷が蓄えられるとともに、電解液280中のリチウムイオン(Li)が、負極活物質層243中の負極活物質に吸収され、かつ、貯蔵される。
図8は、かかるリチウムイオン二次電池100の放電時の状態を模式的に示している。放電時には、図8に示すように、負極シート240から正極シート220に電荷が送られるとともに、負極活物質層243に貯蔵されたリチウムイオンが、電解液280に放出される。また、正極では、正極活物質層223中の正極活物質に電解液280中のリチウムイオンが取り込まれる。
なお、上記はリチウムイオン二次電池の一例を示すものである。リチウムイオン二次電池は上記形態に限定されない。また、同様に金属箔に電極合剤が塗工された電極シートは、他にも種々の電池形態に用いられる。例えば、他の電池形態として、円筒型電池或いはラミネート型電池などが知られている。円筒型電池は、円筒型の電池ケースに捲回電極体を収容した電池である。また、ラミネート型電池は、正極シートと負極シートとをセパレータを介在させて積層した電池である。
図9は、ここで提案される非水系二次電池としてリチウムイオン二次電池100Aを示している。図10は、捲回電極体200Aの正極シート220と負極シート240Aとの積層構造を示す断面図である。さらに、図11は、かかるリチウムイオン二次電池100Aの構造を模式的に示す断面図である。
リチウムイオン二次電池100Aの負極活物質層243Aは、負極活物質粒子として天然黒鉛と人造黒鉛を含んでいる。また、負極活物質層243Aは、図10および図11に示すように、正極活物質層223に対向している部位A1と、正極活物質層223に対向していない部位A2,A3とを有している。負極活物質層243Aのうち正極活物質層223に対向している部位A1では、正極活物質層223に対向していない部位A2,A3に比べて天然黒鉛の割合が大きい。さらに、正極活物質層223に対向していない部位A2,A3では、正極活物質層223に対向している部位A1に比べて人造黒鉛の割合が大きい。
ここで、天然黒鉛は、自然界において長い年月を掛けて黒鉛化した黒鉛材料である。これに対して、人造黒鉛は、工業生産によって黒鉛化させた黒鉛材料である。これらの黒鉛材料は、炭素六角網平面が複数の層を形成するように重なった層構造を有している。この場合、充電時には、リチウムイオンは黒鉛材料のエッジ部(層のエッジ部)から黒鉛材料の層間に侵入し、層間に広がっていく。
この実施形態では、天然黒鉛としては、例えば、鱗片状の黒鉛粒子(鱗片状黒鉛(Flake Graphite)とも称される。)を用いることができる。さらに、天然黒鉛は、例えば、少なくとも一部が非晶質炭素膜によって覆われていてもよい。ここで、非晶質炭素膜は、非晶質な炭素材料よりなる膜である。例えば、核となる天然黒鉛にピッチを混ぜて焼くことによって、少なくとも一部が非晶質炭素膜によって覆われた天然黒鉛を得ることができる。
なお、ここで、好ましくは、天然黒鉛は、ラマン分光法におけるいわゆるR値が、0.2~0.6であり、人造黒鉛はR値が0.2以下であるとよい。なお、上述したように非晶質炭素膜が形成された天然黒鉛(非晶質コートされた天然黒鉛)では、非晶質炭素膜が形成された状態でのR値で評価される。ここで「R値」は、2つのラマン分光バンド、黒鉛構造由来のGバンド(1580cm-1)と構造の乱れ(Disorder)に起因するDバンド(1360cm-1)の比であるR値と呼ばれる強度比(R=I1360/I1580)である。ここで、ラマン分光バンドを得る装置としては、例えば、サーモフィッシャー社製のNicolet分散型レーザーラマン装置を用いることができる。
この実施形態では、負極活物質層243Aを形成する方法は、例えば、以下の工程A~Dを含んでいる。
工程Aでは、第1合剤を用意する。第1合剤は、負極集電体241Aのうち、正極活物質層223に対向している部位A1に相当する部位に塗工される合剤である。
工程Bでは、第2合剤を用意する。第2合剤は、負極集電体241Aのうち、正極活物質層223に対向していない部位A2,A3に相当する部位に塗工される合剤である。
工程Cでは、工程Aで用意された第1合剤を負極集電体241Aのうち、正極活物質層223に対向する部位A1に相当する部位に塗工する。
工程Dでは、工程Bで用意された第2合剤を負極集電体241Aのうち、正極活物質層223に対向しない部位A2,A3に相当する部位に塗工する。
工程Aで用意する第1合剤には、例えば、天然黒鉛とバインダと溶媒とを混ぜ合わせたペーストを用意するとよい。これにより負極活物質粒子として、人造黒鉛は含まず天然黒鉛を含むペーストを得ることができる。また、負極活物質粒子として、天然黒鉛と人造黒鉛とを適当な割合で混ぜ合わせたペーストを用意してもよい。また、例えば、重量割合において天然黒鉛:人造黒鉛=9:1としたペーストを用意してもよい。
工程Bで用意する第2合剤には、例えば、人造黒鉛とバインダと溶媒とを混ぜ合わせたペーストを用意するとよい。これにより負極活物質粒子として、天然黒鉛は含まず人造黒鉛を含むペーストを得ることができる。また、負極活物質粒子として、天然黒鉛と人造黒鉛とを適当な割合で混ぜ合わせたペーストを用意してもよい。また、例えば、重量割合において天然黒鉛:人造黒鉛=1:9としたペーストを用意してもよい。
以下、工程C,工程Dに関し、負極活物質層243Aが形成される工程について、一実施例を説明する。
図12は、負極活物質層243Aが形成される工程を示す図である。負極活物質層243Aは、図12に示すように、上記工程Aで用意された第1合剤と、工程Bで用意された第2合剤を負極集電体241Aの所定部位に塗布し、乾燥後、プレスして形成される。この負極活物質層243Aを形成する製造装置においては、図12に示すように、負極集電体241Aを走行させる走行経路12と、負極集電体241Aに負極活物質層243Aとなる合剤ペーストを塗布する塗布装置14と、負極集電体241Aに塗布された合剤を乾燥させる乾燥炉16とを備えている。
走行経路12は、負極集電体241Aを走行させる経路である。この実施形態では、走行経路12には、負極集電体241Aを走行させる所定の経路に沿って複数のガイド12bが配置されている。走行経路12の始端には、負極集電体241Aを供給する供給部32が設けられている。供給部32には、予め巻き芯32aに巻き取られた負極集電体241Aが配置されている。供給部32からは適宜に適当な量の負極集電体241Aが走行経路12に供給される。また、走行経路12の終端には負極集電体241Aを回収する回収部34が設けられている。回収部34は、走行経路12で所定の処理が施された負極集電体241Aを巻き芯34aに巻き取る。
この実施形態では、その後、作成される捲回電極体200(図10および図11参照)において、正極活物質層223に対向する部位A1と、正極活物質層223に対向しない部位A2,A3とで、負極活物質層243に含まれる負極活物質粒子の構成を異ならせている。このため、電極材料塗布装置14は、正極活物質層223に対向する部位A1と、正極活物質層223に対向しない部位A2、A3とで、負極活物質粒子の構成を異ならせた合剤を塗布する。
流路41、42は、それぞれ溶媒に負極活物質粒子が分散したスラリーが流通し得る流路である。この実施形態では、流路41、42は、それぞれタンク47、48から塗布部45へ至っている。フィルタ43、44は、流路41、42内に配置されている。この実施形態では、タンク47、48には、正極活物質層223に対向する部位A1に塗布する第1合剤と、相対的に平衡電位が低い負極活物質層を形成するのに用いられる第2合剤とが用意されている。第1合剤と第2合剤は、上述したように溶媒に含まれる負極活物質粒子の種類が異なっている。また、第1合剤と第2合剤とは、容易に混ざり合わないことが好ましい。例えば、第1合剤の固形分濃度と第2合剤の固形分濃度を適切に調整することによって、第1合剤と第2合剤とが混ざり難くなる。
塗布部45は、負極集電体241Aのうち、捲回された後に正極活物質層223に対向する部位A1(図11参照)に上記第1合剤を塗布する。また、塗布部45は、負極集電体241Aのうち、捲回された後に正極活物質層223に対向しない部位A2、A3に、上記第2合剤を塗布する。図13は、この負極活物質層243Aの形成に用いられるダイの一例を示す図である。この実施形態では、塗布部45には、例えば、図13に示すように、横長の吐出口62を有するダイ60が用いられている。ダイ60の吐出口62は、中間部分62aと両側部62b1、62b2とが仕切られている。
ここでは、上述したように、正極活物質層223に対向する部位A1と、正極活物質層223に対向しない部位A2,A3とで、負極活物質層243Aに含まれる負極活物質粒子の構成を適当に異ならせた評価用セルを作成した。そして、各評価用セルについて、反応抵抗と、容量維持率(ここでは、所定の高温環境に保存した後の容量維持率)を評価した。ここで、評価用セルは円筒型のいわゆる18650型セル(図示省略)で構成した。また、評価用セルには、負極活物質層の構造が異なるサンプル1~5を用意した。
正極における正極活物質層を形成するにあたり正極合剤を調製した。ここで、正極合剤は、正極活物質として三元系のリチウム遷移金属酸化物(LiNi1/3Co1/3Mn1/3O2)、導電材としてアセチレンブラック(AB)、バインダとしてポリフッ化ビニリデン(PVDF)をそれぞれ用いた。ここでは、正極活物質と、導電材と、バインダの質量比を、正極活物質:導電材:バインダ=91:6:3とした。これら正極活物質と、導電材と、バインダとを、イオン交換水と混合することによって正極合剤を調製した。次いで、正極合剤を正極集電体の両面に塗布して乾燥させた。ここでは、正極集電体としてのアルミニウム箔(厚さ15μm)を用いた。これにより、正極集電体の両面に正極活物質層を備えた正極(正極シート)を作製した。正極シートは、乾燥後、ローラプレス機によって圧延することによって厚さを110μmにした。正極集電体への正極合剤の塗布量は、正極合剤が乾燥した後において、正極集電体の単位面積あたりに、正極活物質層が25mg/cm2になるように設定した。
ここではまず、負極合剤は、負極活物質粒子、増粘剤としてカルボキシメチルセルロース(CMC)、バインダをそれぞれ用いた。サンプルAでは、バインダに、ゴム系バインダであるスチレン・ブタジエンゴム(SBR)が用いられている。
セパレータとしては、ポリプロピレン(PP)と、ポリエチレン(PE)の三層構造(PP/PE/PP)の多孔質シートからなるセパレータを用いた。ここでは、ポリプロピレン(PP)とポリエチレン(PE)の質量比を、PP:PE:PP=3:4:3とした。
上記で作製した負極と、正極と、セパレータとを用いて、試験用の18650型セル(リチウムイオン電池)を構築した。ここでは、セパレータを介在させた状態で、正極シートと負極シートとを積層して捲回した円筒形状の捲回電極体を作製した。そして、捲回電極体を円筒形状の電池ケースに収容し、非水電解液を注液して封口し、評価用セルを構築した。ここで、非水電解液としては、エチレンカーボネート(EC)と、ジメチルカーボネート(DMC)と、エチルメチルカーボネート(EMC)とを、所定の体積比(EC:DMC:EMC=3:4:3)で混合溶媒に、リチウム塩としての1mol/LのLiPF6を溶解させた電解液を用いた。
ここでコンディショニングは、次の手順1、2によって行なわれる。
手順1:1Cの定電流充電にて4.1Vに到達した後、5分間休止する。
手順2:手順1の後、定電圧充電にて1.5時間充電し、5分間休止する。
かかるコンディショニングでは、初期充電によって所要の反応が生じてガスが発生する。また、負極活物質層などに所要の被膜形成が形成される。
上記コンディショニングの後、評価用セルについて定格容量が測定される。定格容量の測定は、次の手順1~3によって測定されている。なお、ここでは温度による影響を一定にするため、定格容量は温度25℃の温度環境において測定されている。
手順1:1Cの定電流放電によって3.0Vに到達後、定電圧放電にて2時間放電し、その後、10秒間休止する。
手順2:1Cの定電流充電によって4.1Vに到達後、定電圧充電にて2.5時間充電し、その後、10秒間休止する。
手順3:0.5Cの定電流放電によって3.0Vに到達後、定電圧放電にて2時間放電し、その後、10秒間停止する。
ここで、手順3における定電流放電から定電圧放電に至る放電における放電容量(CCCV放電容量)を「定格容量」とする。
SOC調整は、次の1、2の手順によって調整される。ここで、SOC調整は、上記コンディショニング工程および定格容量の測定の後に行なうとよい。また、ここでは、温度による影響を一定にするため、25℃の温度環境下でSOC調整を行なっている。
手順1:3Vから1Cの定電流で充電し、定格容量の凡そ60%の充電状態(SOC60%)にする。
手順2:手順1の後、2.5時間、定電圧充電する。
これにより、評価用セルは、所定の充電状態に調整することができる。なお、ここでは、SOCを60%に調整する場合を記載しているが、手順1で充電状態を変更することによって、任意の充電状態に調整できる。例えば、SOC90%に調整する場合には、手順1において、評価用セルを定格容量の90%の充電状態(SOC90%)にするとよい。
初期容量の測定は、例えば、所定の充電状態に調整した評価用セルを、25℃の温度条件下において、端子間電圧が4.1Vになるまで1Cの定電流にて充電し、続いて合計充電時間が2.5時間になるまで定電圧で充電した(CC-CV充電)。充電完了から10分間休止した後、25℃において、4.1Vから3.0Vまで0.33C(1/3C)の定電流で放電させ、続いて合計放電時間が4時間となるまで定電圧で放電させた。このときの放電容量を各電池の初期容量Q1[Ah]とした。ここでは、SOC90%に評価用セルを調整した上で、初期容量を測定した。
反応抵抗は、交流インピーダンス測定法によって測定される反応抵抗である。交流インピーダンス測定法による。図14は、交流インピーダンス測定法における、Cole-Coleプロット(ナイキスト・プロット)の典型例を示す図である。図14に示すように、交流インピーダンス測定法における等価回路フィッティングによって得られるCole-Coleプロットを基に、直流抵抗(Rsol)と、反応抵抗(Rct)を算出することができる。ここで、反応抵抗(Rct)は、下記の式で求めることができる。
Rct=(Rsol+Rct)-Rsol;
ここで、容量維持率(保存後容量維持率)は、所定の充電状態に調整された評価用セルを所定環境で所定時間保存した後、初期容量と同じ条件で放電容量(以下、適宜に「保存後容量」という。)を測定し、比(保存後容量)/(初期容量)で求められる。ここでは、「保存後容量」は、SOC90%に調整した後、60℃の温度環境で30日間保存した評価用セルを基に測定した放電容量である。
「保存後容量維持率」=(保存後容量)/(初期容量)×100(%);
サンプル1では、負極活物質層243A(図11参照)のうち、正極活物質層223に対向している部位A1に負極活物質粒子として天然黒鉛を用い、正極活物質層223に対向していない部位A2,A3にも負極活物質粒子として天然黒鉛を用いた。この場合、反応抵抗は、531mΩであり、保存後容量維持率は、78.7%であった。サンプル1では、-30℃における反応抵抗(mΩ)を低く抑えることができるが、保存後容量維持率(%)が低くなる傾向があった。
サンプル2では、負極活物質層243A(図11参照)のうち、正極活物質層223に対向している部位A1に負極活物質粒子として人造黒鉛を用い、正極活物質層223に対向していない部位A2,A3に負極活物質粒子として人造黒鉛を用いた。この場合、反応抵抗は、2653mΩであり、保存後容量維持率は、84.5%であった。サンプル2では、保存後容量維持率(%)を高く維持できるものの、-30℃における反応抵抗(mΩ)が高くなる傾向があった。
サンプル3では、負極活物質層243A(図11参照)のうち、正極活物質層223に対向している部位A1に負極活物質粒子として人造黒鉛を用い、正極活物質層223に対向していない部位A2,A3に負極活物質粒子として天然黒鉛を用いた。この場合、反応抵抗は、2634mΩであり、保存後容量維持率は、81.3%であった。サンプル3では、サンプル2ほどではないが保存後容量維持率(%)を高く維持できる。しかしながら、-30℃における反応抵抗(mΩ)はサンプル2と同程度に高くなる傾向があった。
サンプル4では、負極活物質層243A(図11参照)のうち、正極活物質層223に対向している部位A1および正極活物質層223に対向していない部位A2,A3において、天然黒鉛と人造黒鉛を所定の割合で混合した混合物を負極活物質粒子として用いた。ここでは、質量割合にて、天然黒鉛:人造黒鉛=93:7とした。この場合、反応抵抗は、743mΩであり、保存後容量維持率は、79.4%であった。サンプル4では、-30℃における反応抵抗(mΩ)を低く抑えることができるが、保存後容量維持率(%)が低くなる傾向があった。
サンプル5では、負極活物質層243A(図11参照)のうち、正極活物質層223に対向している部位A1に負極活物質粒子として天然黒鉛を用い、正極活物質層223に対向していない部位A2,A3に負極活物質粒子として人造黒鉛を用いた。この場合、反応抵抗は、527mΩであり、保存後容量維持率は、82.6%であった。サンプル5では、-30℃における反応抵抗(mΩ)を低く抑えることができ、さらに保存後容量維持率(%)を高く維持できる傾向が見られた。
かかる要因として、本発明者は、人造黒鉛が天然黒鉛よりも、炭素の層が揃っており、リチウムイオンの吸収と放出がスムーズに行われる点、特に、SEI形成量が抑えられる点に着目している。ここで、SEI(solid electrolyte interface)は、リチウムが挿入できるように黒鉛の表面を不活性化・安定化させる被膜を意味している。SEIは、電解液の還元的分解反応によって形成され得る。かかるSEIは黒鉛にリチウムイオンの挿入・脱離が起こるためには必須のものである。しかし、SEIは電解液の還元的分解反応によって生成されるため、その反応に電荷が消費されることになる。これは不可逆容量の原因となる。
なお、ここで好ましくは、天然黒鉛は、ラマン分光法におけるいわゆるR値が、0.2~0.6であり、人造黒鉛はR値が0.2以下であるとよい。ここで「R値」は、上述したように、2つのラマン分光バンド、黒鉛構造由来のGバンド(1580cm-1)と構造の乱れ(Disorder)に起因するDバンド(1360cm-1)の比であるR値と呼ばれる強度比(R=I1360/I1580)である。すなわち、R値が高いほど黒鉛構造が乱れており、反対にR値が低いほど黒鉛構造が整っている。天然黒鉛のR値が0.2~0.6とし、人造黒鉛のR値が0.2以下とするとことにより、天然黒鉛よりも黒鉛構造がより整っている人造黒鉛を選択するとよい。この場合、より好ましくは、天然黒鉛のR値0.22以上で選択してもよい。また、人造黒鉛は、R値を0.18未満としてもよい。これにより、天然黒鉛と人造黒鉛とでR値の差をより明確に生じさせることができる。また、かかるR値は、少なくとも100個以上の粒子を抽出し、その平均値で評価するとよい。
12 走行経路
14 電極材料塗布装置(塗布装置)
16 乾燥炉
32 供給部
34 回収部
34b 制御部
34c モータ
41、42 流路
43、44 フィルタ
45 塗布部
46 バックロール
47、48 タンク
49、50 ポンプ
60 ダイ
62 吐出口
62a 中間部分
62b1 両側部
100、100A リチウムイオン二次電池
105 粘着テープ
110 両面テープ
115 ステージ
120 試料
125 チャック
162 負極集電体
164 負極活物質層
166 負極シート
200、200A 捲回電極体
220 正極シート
221 正極集電体
222 未塗工部
223 正極活物質層
240、240A 負極シート
241、241A 負極集電体
242、242A 未塗工部
243、243A 負極活物質層
245 隙間
262、264 セパレータ
280 電解液
290 充電器
300 電池ケース
320 容器本体
340 蓋体
350 注液孔
352 封止キャップ
360 安全弁
420 電極端子
440 電極端子
610 正極活物質粒子
620 導電材
630 バインダ
710 負極活物質粒子
730 バインダ
1000 車両
WL 捲回軸
Claims (9)
- 正極集電体と、
前記正極集電体に保持された正極活物質層と、
負極集電体と、
前記負極集電体に保持され、前記正極活物質層を覆うように配置された負極活物質層とを備え、
前記負極活物質層は、負極活物質粒子として天然黒鉛と人造黒鉛とを含み、
前記負極活物質層は、
前記正極活物質層に対向している部位と、前記正極活物質層に対向していない部位とを有し、
前記正極活物質層に対向している部位では、前記正極活物質層に対向していない部位に比べて天然黒鉛の割合が大きく、かつ、
前記正極活物質層に対向していない部位では、前記正極活物質層に対向している部位に比べて人造黒鉛の割合が大きい、リチウムイオン二次電池。 - 前記負極活物質層のうち前記正極活物質層と対向している部位では、前記天然黒鉛と前記人造黒鉛のうち前記天然黒鉛の重量割合が90%以上である、請求項1に記載されたリチウムイオン二次電池。
- 前記負極活物質層のうち前記正極活物質層と対向していない部位では、前記天然黒鉛と前記人造黒鉛のうち前記人造黒鉛の重量割合が90%以上である、請求項1または2に記載されたリチウムイオン二次電池。
- 前記天然黒鉛は、ラマン分光法におけるR値が0.2~0.6であり、かつ、前記人造黒鉛は前記R値が0.2以下である、請求項1から3までの何れか一項に記載されたリチウムイオン二次電池。
- 前記負極活物質層のうち正極活物質層に対向している部位に用いられている負極活物質粒子の平均のR値(Ra)と、正極活物質層に対向していない部位に用いられている負極活物質粒子の平均のR値(Rb)との比(Ra/Rb)が、(Ra/Rb)≧1.2である、請求項1から4までの何れか一項に記載されたリチウムイオン二次電池。
- 前記負極活物質層は、バインダを含み、
前記負極活物質層のうち前記正極活物質層と対向していない部位では、前記負極活物質層のうち前記正極活物質層と対向している部位に比べて、前記バインダの含有量が多い、請求項1から5までの何れか一項に記載されたリチウムイオン二次電池。 - 前記天然黒鉛は、少なくとも一部が非晶質炭素膜で覆われている、請求項1から6までの何れか一項に記載されたリチウムイオン二次電池。
- 請求項1から7までの何れか一項に記載されたリチウムイオン二次電池を複数組み合わせた組電池。
- 請求項1から7までの何れか一項に記載されたリチウムイオン二次電池、又は、請求項8に記載された組電池を備えた車両駆動用電池。
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/JP2011/073249 WO2013051155A1 (ja) | 2011-10-07 | 2011-10-07 | リチウムイオン二次電池 |
DE112011105715.6T DE112011105715B4 (de) | 2011-10-07 | 2011-10-07 | Lithiumionenakkumulator |
US14/349,437 US9972844B2 (en) | 2011-10-07 | 2011-10-07 | Lithium-ion secondary battery |
JP2013537371A JP6144626B2 (ja) | 2011-10-07 | 2011-10-07 | リチウムイオン二次電池 |
CN201180074017.6A CN103875118B (zh) | 2011-10-07 | 2011-10-07 | 锂离子二次电池 |
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Cited By (9)
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Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005019399A (ja) * | 2003-06-06 | 2005-01-20 | Jfe Chemical Corp | リチウムイオン二次電池用負極材料およびその製造方法、ならびにリチウムイオン二次電池用負極およびリチウムイオン二次電池 |
JP2010135313A (ja) * | 2008-10-31 | 2010-06-17 | Hitachi Maxell Ltd | 電気化学素子 |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3059820B2 (ja) | 1992-04-09 | 2000-07-04 | 三洋電機株式会社 | リチウム二次電池 |
CN2574229Y (zh) | 2001-04-11 | 2003-09-17 | 日立马库塞鲁株式会社 | 扁平形非水电解质电池 |
CN2574299Y (zh) * | 2002-07-05 | 2003-09-17 | 郭建军 | 一种开关式音频功放机 |
US7396612B2 (en) * | 2003-07-29 | 2008-07-08 | Matsushita Electric Industrial Co., Ltd. | Lithium ion secondary battery |
CN101127394B (zh) | 2006-08-15 | 2011-05-18 | 深圳市比克电池有限公司 | 一种含有石墨的锂二次电池负极及其制造方法 |
US20080121892A1 (en) * | 2006-11-29 | 2008-05-29 | Tpo Displays Corp. | Low temperature poly silicon liquid crystal display |
JP2007242630A (ja) | 2007-05-14 | 2007-09-20 | Mitsubishi Chemicals Corp | 非水系二次電池 |
JP5213015B2 (ja) | 2007-09-04 | 2013-06-19 | Necエナジーデバイス株式会社 | リチウムイオン二次電池 |
JP2010073618A (ja) | 2008-09-22 | 2010-04-02 | Sony Corp | 負極および二次電池 |
JP2010097696A (ja) | 2008-10-14 | 2010-04-30 | Nec Tokin Corp | リチウムイオン電池 |
JP5787196B2 (ja) | 2011-07-29 | 2015-09-30 | トヨタ自動車株式会社 | リチウムイオン二次電池 |
-
2011
- 2011-10-07 JP JP2013537371A patent/JP6144626B2/ja active Active
- 2011-10-07 CN CN201180074017.6A patent/CN103875118B/zh active Active
- 2011-10-07 DE DE112011105715.6T patent/DE112011105715B4/de active Active
- 2011-10-07 WO PCT/JP2011/073249 patent/WO2013051155A1/ja active Application Filing
- 2011-10-07 US US14/349,437 patent/US9972844B2/en active Active
- 2011-10-07 KR KR1020147011176A patent/KR101599168B1/ko active IP Right Grant
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005019399A (ja) * | 2003-06-06 | 2005-01-20 | Jfe Chemical Corp | リチウムイオン二次電池用負極材料およびその製造方法、ならびにリチウムイオン二次電池用負極およびリチウムイオン二次電池 |
JP2010135313A (ja) * | 2008-10-31 | 2010-06-17 | Hitachi Maxell Ltd | 電気化学素子 |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10020511B2 (en) | 2012-09-10 | 2018-07-10 | Toyota Jidosha Kabushiki Kaisha | Lithium secondary battery |
JP2014229517A (ja) * | 2013-05-23 | 2014-12-08 | 日立化成株式会社 | リチウムイオン二次電池用負極材、リチウムイオン二次電池用負極及びリチウムイオン二次電池 |
JP2015032478A (ja) * | 2013-08-02 | 2015-02-16 | トヨタ自動車株式会社 | 二次電池 |
CN105637682A (zh) * | 2013-10-28 | 2016-06-01 | 日本瑞翁株式会社 | 锂离子二次电池负极用浆料组合物、锂离子二次电池用负极、锂离子二次电池、以及制造方法 |
KR101569055B1 (ko) | 2013-12-03 | 2015-11-16 | 주식회사 엘지화학 | 출력 및 용량 특성이 다른 전극들을 포함하고 있는 하이브리드형 이차전지 |
EP3054509A4 (en) * | 2014-07-29 | 2016-10-26 | Lg Chemical Ltd | GRAPHITE SECONDARY PARTICLE, AND LITHIUM RECHARGEABLE BATTERY COMPRISING SAME |
US10361426B2 (en) | 2014-07-29 | 2019-07-23 | Lg Chem, Ltd. | Secondary graphite particle and secondary lithium battery comprising the same |
WO2016136803A1 (ja) * | 2015-02-25 | 2016-09-01 | 新日鉄住金化学株式会社 | リチウムイオン二次電池負極用活物質、それを用いた二次電池負極及び二次電池 |
CN108701816A (zh) * | 2016-09-29 | 2018-10-23 | 株式会社Lg化学 | 包括天然石墨和人造石墨的多层负极以及包括该多层负极的锂二次电池 |
CN108701816B (zh) * | 2016-09-29 | 2021-11-12 | 株式会社Lg化学 | 包括天然石墨和人造石墨的多层负极以及包括该多层负极的锂二次电池 |
JP2020047506A (ja) * | 2018-09-20 | 2020-03-26 | トヨタ自動車株式会社 | 電極の製造方法 |
Also Published As
Publication number | Publication date |
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CN103875118A (zh) | 2014-06-18 |
JPWO2013051155A1 (ja) | 2015-03-30 |
US20140248528A1 (en) | 2014-09-04 |
DE112011105715T5 (de) | 2014-06-26 |
JP6144626B2 (ja) | 2017-06-07 |
US9972844B2 (en) | 2018-05-15 |
KR20140072132A (ko) | 2014-06-12 |
CN103875118B (zh) | 2016-03-30 |
DE112011105715B4 (de) | 2021-02-25 |
KR101599168B1 (ko) | 2016-03-02 |
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