WO2023182030A1 - 電極、非水電解質二次電池、および電極の製造方法 - Google Patents

電極、非水電解質二次電池、および電極の製造方法 Download PDF

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WO2023182030A1
WO2023182030A1 PCT/JP2023/009539 JP2023009539W WO2023182030A1 WO 2023182030 A1 WO2023182030 A1 WO 2023182030A1 JP 2023009539 W JP2023009539 W JP 2023009539W WO 2023182030 A1 WO2023182030 A1 WO 2023182030A1
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Prior art keywords
electrode
binder
sheet
peak
composite material
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PCT/JP2023/009539
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English (en)
French (fr)
Japanese (ja)
Inventor
礼子 泉
大貴 山下
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Panasonic Intellectual Property Management Co Ltd
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Panasonic Intellectual Property Management Co Ltd
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Priority to EP23774627.6A priority Critical patent/EP4503153A4/en
Priority to US18/846,385 priority patent/US20250192181A1/en
Priority to CN202380027068.6A priority patent/CN118891742A/zh
Priority to JP2024510020A priority patent/JPWO2023182030A1/ja
Publication of WO2023182030A1 publication Critical patent/WO2023182030A1/ja
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/50—Electrodes characterised by their material specially adapted for lithium-ion capacitors, e.g. for lithium-doping or for intercalation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/26—Electrodes characterised by their structure, e.g. multi-layered, porosity or surface features
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/32—Carbon-based
    • H01G11/38—Carbon pastes or blends; Binders or additives therein
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/26—Electrodes characterised by their structure, e.g. multi-layered, porosity or surface features
    • H01G11/28—Electrodes characterised by their structure, e.g. multi-layered, porosity or surface features arranged or disposed on a current collector; Layers or phases between electrodes and current collectors, e.g. adhesives
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present disclosure relates to an electrode, a nonaqueous electrolyte secondary battery including the electrode, and a method for manufacturing the electrode.
  • Electrodes for non-aqueous electrolyte secondary batteries such as lithium-ion batteries are generally made by applying an electrode mixture slurry containing active materials, binders, etc. to the surface of a core material, which is metal foil, and then drying and compressing the coating film. Produced by wet method. In this case, there is a problem that migration, in which the binder moves during drying of the coating film, is likely to occur. When binder migration occurs, the amount of binder becomes larger on the surface side of the coating film (electrode composite material layer) than on the core material side, resulting in an uneven distribution of binder in the thickness direction of the electrode composite material layer.
  • Patent Document 1 discloses an electrode composite sheet prepared by mixing an active material, a fibrillable binder such as polytetrafluoroethylene (PTFE), and a conductive material using a mill to fibrillate the PTFE. ing.
  • PTFE polytetrafluoroethylene
  • An object of the present disclosure is to provide an electrode with good productivity and a high-strength composite material sheet.
  • An electrode according to the present disclosure includes a core material and a composite sheet joined to the surface of the core material, the composite sheet includes an active material and a fibrous binder, and the binder includes:
  • the ratio of the area of the first peak and the second peak other than its spinning sideband is 0.01% or more and 5.0% or less.
  • a nonaqueous electrolyte secondary battery according to the present disclosure includes the above electrode.
  • the above electrode configuration is preferably applied to a positive electrode.
  • a method for manufacturing an electrode according to the present disclosure includes an electrode mixture in which an active material and a binder mainly composed of polytetrafluoroethylene are mixed, and the solid content concentration is substantially 100% and the binder is fibrillated.
  • a first step of producing a composite material a second step of producing a composite sheet by forming and rolling an electrode composite material into a sheet shape, and a third step of joining the composite material sheet to the surface of the core material.
  • the composite sheet according to the present disclosure has a smooth surface and high tensile strength, and contributes to improving durability (cycle characteristics) when applied to an electrode of a non-aqueous electrolyte secondary battery, for example.
  • FIG. 2 is a cross-sectional view of an electrode that is an example of an embodiment.
  • FIG. 3 is a diagram showing an electrode composite material that is an example of an embodiment.
  • FIG. 3 is a diagram showing a step of manufacturing an electrode composite material in an electrode manufacturing process that is an example of an embodiment.
  • FIG. 3 is a diagram showing a process of manufacturing a composite material sheet and a process of joining it to a core material in an electrode manufacturing process that is an example of an embodiment.
  • the electrode according to the present disclosure is suitable for nonaqueous electrolyte secondary batteries such as lithium ion batteries and lithium secondary batteries, but it can also be applied to batteries containing aqueous electrolytes or power storage devices such as capacitors.
  • an electrode for a non-aqueous electrolyte secondary battery will be cited as an example.
  • the configuration and manufacturing method of an electrode for a non-aqueous electrolyte secondary battery according to the present disclosure may be applied to a negative electrode, it is particularly preferably applied to a positive electrode.
  • a non-aqueous electrolyte secondary battery includes an electrode body including a positive electrode and a negative electrode, and a non-aqueous electrolyte.
  • the non-aqueous electrolyte includes, for example, a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.
  • FIG. 1 is a cross-sectional view of an electrode 10 that is an example of an embodiment.
  • the electrode 10 includes a core material 11 and a composite sheet 12 joined to the surface of the core material 11. It is preferable that the composite material sheet 12 is joined to both sides of the core material 11.
  • the composite material sheet 12 is produced by molding an electrode composite material 20 (see FIG. 2), which will be described later, into a sheet shape, and is joined to the core material 11 to constitute an electrode composite material layer.
  • the electrode 10 may be an elongated electrode constituting a wound electrode body, or may be a rectangular electrode constituting a laminated electrode body.
  • the core material 11 metal foil, a film with a metal layer formed on the surface, or the like can be used.
  • the thickness of the core material 11 is, for example, 5 ⁇ m or more and 20 ⁇ m or less.
  • the core material 11 can be a metal foil containing aluminum as a main component.
  • metal foil containing copper as a main component can be used.
  • the main component means a component having the highest mass ratio.
  • the core material 11 may be an aluminum foil made of substantially 100% aluminum, or may be a copper foil made of substantially 100% copper.
  • the composite material sheet 12 includes an active material 21 and a binder 22.
  • the composite material sheet 12 is produced by molding the electrode composite material 20 containing the active material 21 and the binder 22 into a sheet shape.
  • the binder 22 is a fibrillated fibrous binder, and is polytetrafluoroethylene into which a predetermined branched structure has been introduced.
  • the thickness of the composite sheet 12 applied to the nonaqueous electrolyte secondary battery is, for example, 50 ⁇ m or more and 150 ⁇ m or less, preferably 80 ⁇ m or more and 140 ⁇ m or less, and more preferably 100 ⁇ m or more and 130 ⁇ m or less.
  • the composite material sheet 12 may further contain a conductive material.
  • the composite material sheet 12 when the composite material sheet 12 constitutes the positive electrode composite material layer, it is preferable that the composite material sheet 12 contains a conductive material.
  • the conductive material included in the composite sheet 12 include carbon black such as acetylene black and Ketjen black, carbon nanotubes (CNT), and carbon materials such as graphite.
  • the electrode 10 is a positive electrode, a preferable example of the content of the conductive material in the composite sheet 12 is 0.2% by mass or more and 5.0% by mass or less.
  • a lithium transition metal composite oxide is generally used as the active material of the positive electrode.
  • Metal elements contained in the lithium transition metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, and Sn. , Ta, W, etc. Among these, it is preferable to contain at least one selected from Ni, Co, and Mn.
  • the content of the positive electrode active material is preferably 85% by mass or more and 99% by mass or less, more preferably 90% by mass or more and 99% by mass or less, based on the mass of the composite sheet 12. The amount is also similar to the content of the positive electrode active material).
  • the positive electrode active material is a secondary particle formed by agglomerating a plurality of primary particles.
  • the volume-based median diameter (D50) of the positive electrode active material is preferably 3 ⁇ m or more and 30 ⁇ m or less. D50 means a particle size at which the cumulative frequency is 50% from the smallest particle size in the volume-based particle size distribution, and is also called the median diameter.
  • the particle size distribution of the positive electrode active material can be measured using a laser diffraction type particle size distribution measuring device (for example, MT3000II manufactured by Microtrac Bell Co., Ltd.) using water as a dispersion medium.
  • the active material of the negative electrode examples include carbon-based active materials such as natural graphite such as flaky graphite, lumpy graphite, and earthy graphite, and artificial graphite such as massive artificial graphite (MAG) and graphitized mesophase carbon microbeads (MCMB). is used.
  • carbon-based active materials such as natural graphite such as flaky graphite, lumpy graphite, and earthy graphite
  • artificial graphite such as massive artificial graphite (MAG) and graphitized mesophase carbon microbeads (MCMB).
  • MAG massive artificial graphite
  • MCMB graphitized mesophase carbon microbeads
  • the composite material sheet 12 When the composite material sheet 12 is divided into three equal parts in the thickness direction, and they are defined as a first region, a second region, and a third region from the core material 11 side, the content (a) of the binder 22 in the first region, the second region It is preferable that the content (b) of the binder 22 in the region and the content (c) of the binder 22 in the third region satisfy (ca)/(a+b+c) ⁇ 10%, and (ca)/ It is more preferable to satisfy (a+b+c) ⁇ 5%.
  • the binder 22 In the electrode 10, the binder 22 is not unevenly distributed in a part of the composite sheet 12, but is present substantially uniformly throughout the composite sheet 12.
  • the density of the composite sheet 12 is not particularly limited, but when the composite sheet 12 constitutes a positive electrode composite layer, the density is preferably 2.5 g/cc or more and 4.5 g/cc or less, 3.0 g/cc or more, 4.2 g/cc or less is more preferable, and 3.0 g/cc or more and 4.0 g/cc or less are particularly preferable.
  • the electrode 10 may be provided with an intermediate layer interposed between the core material 11 and the composite material sheet 12.
  • the intermediate layer includes, for example, a conductive material and a binder, improves the bonding strength of the composite sheet 12 to the core material 11, and reduces interfacial resistance.
  • FIG. 2 is a diagram showing an example of the electrode composite material 20, and also shows a state (binder 22x) before the binder 22 is fibrillated.
  • the electrode composite material 20 constituting the composite material sheet 12 includes an active material 21 and a fibrillated fibrous binder 22.
  • the electrode composite material 20 may further contain a conductive material.
  • the electrode mixture 20 is produced by, for example, fibrillating the binder 22x to form the fibrous binder 22 in the process of stirring and mixing the active material 21, the particulate binder 22x, and a conductive material (not shown). It can be made.
  • the fibrous binder 22 is fibrillated by applying a predetermined shearing force to the particulate binder 22x.
  • the fibrous binder 22 is entangled with the particles of the active material 21 and binds the particles to each other, so that the electrode composite material 20 can be molded into a single sheet.
  • the binder 22x is a material that can be fibrillated, adheres to the particle surface of the active material 21, has chemical resistance to electrolyte solution, and has polytetrafluoroethylene (PTFE) as its main component.
  • the binder 22x may contain components other than PTFE particles, such as polyvinylidene fluoride (PVdF), as long as the object of the present disclosure is not impaired, but may contain substantially only PTFE particles. .
  • the average particle diameter of the PTFE particles is not particularly limited, but is preferably 100 ⁇ m or more and 500 ⁇ m or less, more preferably 200 ⁇ m or more and 400 ⁇ m or less.
  • the average particle size of the PTFE particles can be determined by observing the PTFE particles with a scanning electron microscope (SEM). Specifically, 100 randomly selected particles are extracted, the diameter of the circumscribed circle of each of the 100 particles is measured, and each measured value is averaged.
  • the binder 22 has a predetermined branched structure.
  • a PTFE molecule with a branched structure is a molecule that has one or more branch points in the molecule.
  • a PTFE molecule with a linear structure means a molecule that does not have a branch point in the molecule.
  • the binder 22 may be composed only of PTFE molecules having a branched structure, or may be a mixture of PTFE molecules having a branched structure and PTFE molecules having a linear structure. When the binder 22 is a mixture, each molecule does not need to satisfy the area ratio (Z) condition described below, and it is sufficient that the mixture satisfies the area ratio (Z) condition.
  • the area ratio of the second peak other than the spinning sideband (hereinafter sometimes referred to as "area ratio (Z)") satisfies the condition of 0.01% or more and 5.0% or less.
  • the lower limit of the area ratio (Z) is preferably 0.02%, more preferably 0.05%.
  • the upper limit of the area ratio (Z) is preferably 4.5%, more preferably 2.0%, particularly preferably 1.5%.
  • the second peak is mainly a peak derived from F in the branched portion of PTFE, but includes a portion of a peak derived from F in the linear portion.
  • the area ratio (Z) roughly indicates the ratio of branched structures introduced into the molecules of the binder 22. Note that the peak derived from F in the linear portion included in the second peak has no substantial effect on calculating the proportion of the branched structure.
  • the binder 22 in which a branched structure is introduced in which the area ratio (Z) of the solid 19F-NMR spectrum satisfies the above conditions, the kneading properties of the electrode composite material 20 and the stretchability of the composite material sheet 12 are improved, Improves sheet strength.
  • the PTFE constituting the binder 22 may have a branched structure, but at least some of the molecules may be cross-linked. By introducing the crosslinked structure, for example, it becomes easy to achieve both good productivity and high strength of the composite material sheet 12.
  • the content of the binder 22 is preferably 0.1 parts by mass or more and 5.0 parts by mass or less, more preferably 0.2 parts by mass or more and 3 parts by mass or less, with respect to 100 parts by mass of the active material 21, and .3 parts by mass or more and 2 parts by mass or less are particularly preferred. If the content of the binder 22 is within this range, the effect of modifying the composite material sheet 12 will be more significant. As described above, the binder 22 is contained substantially uniformly throughout the composite material sheet 12. Further, the binder 22 has a crystallite size of, for example, 20 nm or more and 32 nm or less. The crystallite size of the binder 22 is determined by X-ray diffraction measurement.
  • FIG. 3 shows the process of mixing the composite material raw materials to produce the electrode composite material 20
  • FIG. 4 shows the process of rolling the electrode composite material 20 to produce the composite material sheet 12 and joining it to the elongated core material 11. Show the process.
  • the electrode 10 is manufactured through the following steps. (1) A first step of mixing the active material 21 and a binder to produce an electrode composite material 20 with a solid content concentration of substantially 100% (see FIG. 3) (2) A second step of forming and rolling the electrode composite material 20 into a sheet shape to produce the composite material sheet 12 (see left in FIG. 4) (3) Third step of joining the composite sheet 12 to the surface of the core material 11 (see right in FIG. 4) Then, in the first to third steps or before the first step, the first Branching of PTFE is performed so that the area ratio of the second peak other than the peak (area ratio (Z)) is 0.01% or more and 5.0% or less.
  • the composite material sheet 12 is manufactured by a dry process using an electrode composite material 20 with a solid content concentration of substantially 100%.
  • the electrode composite material 20 is produced, for example, by stirring and mixing the active material 21, the particulate binder 22x, and the conductive material using a mixer 30.
  • the particulate binder 22x may be fibrillated to some extent before being mixed with other raw materials, that is, before the first step.
  • a conventionally known mechanical stirring mixer that can apply mechanical shearing force can be used.
  • the mixer 30 include a cutter mill (such as Wonder Crusher manufactured by Osaka Chemical Co., Ltd.), a pin mill, a bead mill, a kneader (kneader, Banbury mixer, etc.), a planetary mixer, and a fine particle compounding device (such as a high-speed
  • a cutter mill such as Wonder Crusher manufactured by Osaka Chemical Co., Ltd.
  • a pin mill such as Wonder Crusher manufactured by Osaka Chemical Co., Ltd.
  • a bead mill such as a kneader (kneader, Banbury mixer, etc.)
  • a planetary mixer such as a high-speed
  • a fine particle compounding device such as a high-speed
  • An example is a device in which shear force is generated between a rotating rotor with a special shape and a collision plate.
  • the particulate binder 22x is fibrillated
  • the processing time of the first step (time to apply shear force to the raw material mixture) varies depending on the type of mixer 30, etc., but is preferably within several minutes, for example, 0.5 minutes or more, 10 minutes or more. It is as follows. If the processing time is too long, the amount of conductive material incorporated into the binder 22 may increase, and the conductivity of the composite material sheet 12 may decrease.
  • the first step may include a step of mixing the active material 21 and a conductive material, and a step of mixing a mixture of the active material 21 and the conductive material with a binder. In this case, the amount of conductive material incorporated into the fibrous binder 22 can be reduced.
  • a mechanofusion method may be used for dry mixing of the active material 21 and the conductive material. By applying the mechanofusion method, the binding force of the conductive material to the particle surface of the active material 21 becomes stronger.
  • Mechanofusion reactors include Nobilta (registered trademark) or Mechanofusion (registered trademark) manufactured by Hosokawa Micron Co., Ltd., hybridization system manufactured by Nara Kikai Seisakusho Co., Ltd., Balance Gran manufactured by Freund Turbo Co., Ltd., and Nippon Coke Industry Co., Ltd. Examples include COMPOSI manufactured by Co., Ltd.
  • PTFE is Perform branch processing.
  • branching treatment for PTFE include irradiating linear PTFE with an electron beam or radiation. It is known that when linear PTFE molecules are irradiated with electron beams or radiation, branching occurs, and at this time, crosslinking between molecules may proceed. By appropriately changing the output of the electron beam or radiation, the irradiation time, etc., the degree of branching, that is, the area ratio (Z) can be controlled within the desired range.
  • the branching treatment of PTFE may be performed in any or all of the first to third steps.
  • the active material 21 and the binder 22x PTFE particles
  • Fibrillation of particles may be performed by irradiating electron beams or radiation, but it is preferable to use PTFE particles that have been subjected to a branching treatment in advance. That is, it is preferable to supply PTFE particles that have been irradiated with an electron beam or radiation and have a predetermined branched structure introduced into the first step.
  • PTFE having a branched structure may be used as the binder 22, or a mixture of PTFE having a branched structure and PTFE having a linear structure may be used.
  • PTFE particles having a branched structure and having an area ratio (Z) of 0.01% or more and 5.0% or less may be supplied to the first step.
  • a mixed powder in which PTFE particles having a branched structure and PTFE particles having a linear structure are mixed and the area ratio (Z) is adjusted to 0.01% or more and 5.0% or less is subjected to the first step. May be supplied.
  • the electrode composite material 20 is formed and rolled into a sheet shape by the two rollers 31, thereby obtaining the composite material sheet 12.
  • the two rollers 31 are arranged with a predetermined gap and rotate in the same direction.
  • the electrode composite material 20 is supplied to the gap between the two rollers 31, compressed by the two rollers 31, and stretched into a sheet shape.
  • the two rollers 31 have, for example, the same diameter.
  • the composite material sheet 12 may be passed through the gap between the two rollers 31 multiple times.
  • the thickness of the composite material sheet 12 can be controlled by, for example, the gap between the two rollers 31, the circumferential speed, the number of stretching treatments, etc.
  • the electrode composite material 20 may be formed into a sheet shape using two rollers 31 whose circumferential speed ratios differ by a factor of two or more. By making the circumferential speed ratio of the two rollers 31 different, the composite material sheet 12 can be easily made into a thin film, and productivity can be improved.
  • the composite material sheet 12 may be further compressed to increase its density. In this compression step, a linear pressure of, for example, 1 t/cm or more and 3 t/cm or less may be applied.
  • the elongated composite material sheet 12 is joined to the surface of the elongated core material 11 and cut into a predetermined electrode size, thereby obtaining the electrode 10.
  • FIG. 4 shows how the composite material sheet 12 is bonded to only one side of the core material 11, the composite material sheet 12 is bonded to both surfaces of the core material 11.
  • the two composite material sheets 12 may be joined to both sides of the core material 11 at the same time, or after one sheet is joined to one surface of the core material 11, the other sheet may be joined to the other surface. good.
  • the composite material sheet 12 is bonded to the surface of the core material 11 using two rollers 32.
  • the temperature of the two rollers 32 may be room temperature, and may be 300°C or lower, preferably 200°C or lower.
  • the linear pressure applied by the two rollers 32 is smaller than the linear pressure applied in the compression process, and is, for example, 0.1 t/cm or more and 2 t/cm or less.
  • An intermediate layer may be formed on both sides of the core material 11 to be subjected to this bonding step.
  • Example 1 [Preparation of positive electrode composite sheet] Using NOB300-Nobilta (registered trademark) manufactured by Hosokawa Micron Co., Ltd., 1000 g of lithium transition metal composite oxide, which is a positive electrode active material, and 10 g of carbon black are mixed for 5 minutes, so that the carbon black is coated on the particle surface of the positive electrode active material. A carbon-coated cathode active material was prepared. This carbon-coated cathode active material and the PTFE particles (1) having a peak area ratio (Z) of 19F-NMR of 0.02% were mixed in a mass ratio of 101:0.8 using a Wonder tube manufactured by Osaka Chemical Co., Ltd. The mixture was placed in a crusher and mixed at room temperature and at a rotation speed of 5 on the scale for 5 minutes. Note that the rotation speed of the Wonder Crusher is 28,000 rpm, which is the maximum on the scale 10.
  • the PTFE particles were fibrillated to become fibrous PTFE, and a positive electrode composite material in which the carbon-coated positive electrode active material and the fibrous PTFE were uniformly dispersed was obtained.
  • the obtained positive electrode mixture had a solid content concentration of 100%.
  • This positive electrode composite material was passed between two rollers and rolled to produce a positive electrode composite sheet. The peripheral speed ratio of the two rollers was 1:1.5.
  • the obtained positive electrode composite sheet was compressed by passing it between two rollers at room temperature. The linear pressure applied in this compression step was set to 1 t/cm.
  • the thickness and tensile strength of the obtained positive electrode composite sheet were measured, and the measured values are shown in Table 1 along with the area ratio of 19F-NMR.
  • the thickness of the sheet was measured using a micrometer.
  • the tensile strength of the sheet was measured using a universal testing machine at a tensile speed of 2 cm/min. Further, the kneading properties in the mixing process of the positive electrode mixture were evaluated based on the following criteria, and the evaluation results are shown in Table 1.
  • ⁇ The material is integrated and easy to mold.
  • ⁇ The material is powdery even after kneading and is difficult to mold.
  • the positive electrode composite sheet positive electrode composite material layer
  • Example 2 In producing the positive electrode composite material, the same procedure as in Example 1 was carried out, except that PTFE particles having the 19F-NMR peak area ratio (Z) of 0.06% were used instead of the PTFE particles (1). A positive electrode composite sheet and a positive electrode were produced, and the above evaluations were performed.
  • Example 3 In producing the positive electrode composite material, the same procedure as in Example 1 was carried out, except that PTFE particles having the 19F-NMR peak area ratio (Z) of 2.0% were used instead of the PTFE particles (1). A positive electrode composite sheet and a positive electrode were produced, and the above evaluations were performed.
  • Example 4 In producing the positive electrode mixture, the same procedure as in Example 1 was carried out, except that PTFE particles having the 19F-NMR peak area ratio (Z) of 4.5% were used instead of the PTFE particles (1). A positive electrode composite sheet and a positive electrode were produced, and the above evaluations were performed.
  • ⁇ Comparative example 1> In producing the positive electrode mixture, the same procedure as in Example 1 was carried out, except that PTFE particles having the 19F-NMR peak area ratio (Z) of 0.003% were used instead of the PTFE particles (1). A positive electrode composite sheet and a positive electrode were produced, and the above evaluations were performed.
  • ⁇ Comparative example 2> In producing the positive electrode composite material, the same procedure as in Example 1 was carried out, except that PTFE particles having the above 19F-NMR peak area ratio (Z) of 7.0% were used instead of the PTFE particles (1). A positive electrode composite sheet and a positive electrode were produced, and the above evaluations were performed.
  • the thickness of the sheet obtained through the stretching process under the same conditions was thinner in the examples.
  • the thickness of the positive electrode composite sheet is preferably 100 ⁇ m or more and 130 ⁇ m or less, but in the case of Comparative Example 1, since the positive electrode composite sheet is hard, it is not easy to achieve this thickness.
  • the tensile strength of the sheet decreases as the thickness decreases, but the sheets of Examples 1 to 3 are equivalent to or greater than the sheet of Comparative Example 1, despite being thinner than the sheet of Comparative Example 1. It has strength.
  • Comparative Example 2 when PTFE with a 19F-NMR peak area ratio of more than 5% was used (Comparative Example 2), the strength of the positive electrode composite sheet was significantly reduced, and it was difficult to achieve a preferable sheet thickness. That is, if too many branched structures are introduced into PTFE, high sheet strength cannot be ensured. Furthermore, in Comparative Example 2, the kneading properties of the raw materials were also poor.

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PCT/JP2023/009539 2022-03-24 2023-03-13 電極、非水電解質二次電池、および電極の製造方法 Ceased WO2023182030A1 (ja)

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US18/846,385 US20250192181A1 (en) 2022-03-24 2023-03-13 Electrode, nonaqueous electrolyte secondary battery and method for producing electrode
CN202380027068.6A CN118891742A (zh) 2022-03-24 2023-03-13 电极、非水电解质二次电池和电极的制造方法
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WO2025109996A1 (ja) * 2023-11-22 2025-05-30 パナソニックＩｐマネジメント株式会社 非水電解質二次電池用正極、及び非水電解質二次電池

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JP2019512872A (ja) 2016-03-01 2019-05-16 マックスウェル テクノロジーズ インコーポレイテッド エネルギー貯蔵装置用電極および乾燥したエネルギー貯蔵装置用電極フィルムの製造方法
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WO2025109996A1 (ja) * 2023-11-22 2025-05-30 パナソニックＩｐマネジメント株式会社 非水電解質二次電池用正極、及び非水電解質二次電池

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US20250192181A1 (en) 2025-06-12
CN118891742A (zh) 2024-11-01

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