Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • 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
• • 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
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
• • 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
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
  • H01M10/0562—Solid materials
• • 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
  • H01M4/043—Processes of manufacture in general involving compressing or compaction
  • H01M4/0435—Rolling or calendering
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—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
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • 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
  • 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
  • H01M2004/021—Physical characteristics, e.g. porosity, surface area
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0065—Solid electrolytes
  • H01M2300/0068—Solid electrolytes inorganic
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0088—Composites
  • H01M2300/0091—Composites in the form of mixtures
• • 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 a secondary battery mixture, a secondary battery mixture sheet, a method for producing the same, and a solid secondary battery.
• a slurry obtained by mixing a binder and a solvent is applied to an electrode active material and a conductive aid, and dried to produce a solid secondary battery sheet. is commonly performed.
• fibrillating resins such as polytetrafluoroethylene resins are also used and fibrillated to be used as binders.
• Patent Literature 1 discloses a method for fabricating an electrode in which polytetrafluoroethylene is fibrillated by subjecting a mixture containing an active material and a polytetrafluoroethylene mixed binder material to high shear treatment with a jet mill.
• Patent Document 2 discloses that an inorganic sulfide having a specific composition in which a crystal phase and a glass phase coexist is used as a binder to produce a solid electrolyte layer, a positive electrode, or a negative electrode.
• a fiber having an average diameter d of 0.1 to 2 ⁇ m and an average length L of 0.2 to 50 mm is prepared by an electrospinning method, a microfluidizer method, or a wet spinning method, and the fiber and an inorganic solid electrolyte, and has a solid electrolyte-containing layer with a thickness of t ⁇ m, wherein L and t satisfy the relationship of 100 ⁇ t ⁇ L ⁇ 2500 ⁇ t.
• Patent Document 4 discloses a method for producing a film by mixing sulfur-based solid ion conductor inorganic particles and a tetrafluoroethylene (TFE) polymer to form a paste and then calendering or extruding.
• TFE tetrafluoroethylene
• the present disclosure uses a secondary battery mixture containing a sulfide-based solid electrolyte, a secondary battery mixture sheet containing the mixture, and the secondary battery mixture sheet having good properties
• An object of the present invention is to provide a solid secondary battery.
• the present disclosure provides a secondary battery mixture sheet containing a sulfide-based solid electrolyte with high productivity that can be handled without using a support when forming a secondary battery mixture sheet, and its
• An object of the present invention is to provide a mixture sheet for a secondary battery containing a mixture.
• the present disclosure is a secondary battery mixture containing a sulfide-based solid electrolyte and a binder,
• the binder is a mixture for secondary batteries, characterized in that it is a fibrillar resin.
• the fibrillar resin preferably has a fibrous structure with a fibril diameter (median value) of 100 nm or less.
• the fibrillar resin is preferably polytetrafluoroethylene resin.
• the sulfide-based solid electrolyte preferably has an average particle size of 0.1 ⁇ m or more and 20 ⁇ m or less.
• the sulfide-based solid electrolyte is preferably represented by the following formula (A). aLi 2 S-bX 1 S 2 -cLiX 2 -(1-abc)P 2 S 5 (A) (where 0.6 ⁇ a ⁇ 0.86, 0 ⁇ b ⁇ 0.333, 0 ⁇ c ⁇ 0.3, 0.05 ⁇ b + c ⁇ 0.4, X 1 is Ge, Sn, Ti or Si, X2 represents Cl, Br or I, provided that either b or c is not 0)
• the secondary battery mixture is preferably for a lithium ion solid secondary battery.
• the secondary battery mixture is a secondary battery mixture obtained by using a raw material composition containing a sulfide-based solid electrolyte and a binder, It is preferable that the binder in the raw material composition is a powdery fibrillar resin.
• the raw material composition does not substantially contain a liquid medium.
• the powdery fibrillar resin preferably has a moisture content of 500 ppm or less.
• the powdery fibrillar resin is preferably a powdery polytetrafluoroethylene resin.
• the powdery polytetrafluoroethylene resin preferably has a standard specific gravity of 2.12 to 2.20.
• the powdery polytetrafluoroethylene resin preferably contains 50% by mass or more of polytetrafluoroethylene resin having a secondary particle size of 450 ⁇ m or more.
• the present disclosure is also a secondary battery mixture sheet containing the secondary battery mixture.
• the present disclosure provides a step (1) of applying a shearing force while mixing a raw material composition containing a sulfide-based solid electrolyte and a binder.
• Step (3) wherein the binder is a powdery fibrillar resin.
• the present disclosure is also a solid secondary battery having the mixture sheet for a secondary battery.
• the present disclosure when forming a secondary battery mixture sheet containing a sulfide-based solid electrolyte, no solvent is used, and a powdery binder with little moisture is used to prevent deterioration of the sulfide-based solid electrolyte. A battery with less energy can be manufactured.
• the present disclosure provides a secondary battery mixture sheet containing a sulfide-based electrolyte, which has high productivity such that it can be handled without using a support when forming a secondary battery mixture sheet, and a secondary battery mixture sheet thereof.
• a mixture sheet for a secondary battery containing the mixture can be provided.
• the present disclosure provides a secondary battery mixture and a mixture sheet containing the same that can be suitably used in a sulfide-based solid secondary battery.
• a fibrillar resin such as polytetrafluoroethylene resin (PTFE) is used as a binder.
• PTFE polytetrafluoroethylene resin
• a resin that dissolves in a solvent such as a copolymer of vinylidene fluoride and hexafluoropropylene, is used as a binder, and a slurry containing this is applied and dried. , a method of creating a mixture for a solid secondary battery was common.
• PTFE can be used as a binding agent.
• the fibrillated PTFE entangles other powder components and binds the powder components, thereby acting as a binder when molding the powder components.
• the present disclosure uses a fibrillar resin as a binder to obtain a secondary battery having good properties without using a solvent.
• the inventors have found that a mixture for a battery and a mixture sheet containing the same can be obtained, thereby completing the present disclosure.
• the secondary battery mixture that constitutes the solid secondary battery It is desired that the sheet can be handled without a support. Furthermore, from the viewpoint of manufacturability, these secondary battery mixture sheets are desired to withstand winding with a large curvature when wound into a roll. Therefore, improvement in flexibility is also desired.
• a fibril resin as a binder it is possible to produce a mixture sheet for a secondary battery without using a solvent. A mixture sheet for a secondary battery can be produced.
• the mixture sheet for a secondary battery of the present disclosure can be easily handled and have good flexibility and strength.
• the secondary battery mixture of the present disclosure is obtained by using a raw material composition containing a sulfide-based solid electrolyte and a binder, and the binder may be a powdery fibrillar resin. preferable. Since a powdery binder is used as a raw material instead of a binder-containing dispersion, there is little water content in the mixture for secondary batteries, and problems due to mixing of water do not occur. . This has the advantage that the battery performance can be improved. Also, the battery can have excellent ion conductivity.
• the raw material composition substantially does not contain a liquid medium.
• the secondary battery mixture of the present disclosure has the advantage of not using a solvent in its production. That is, the conventional method for forming a mixture for a secondary battery uses a solvent in which a binder is dissolved to prepare a slurry in which powder as a mixture component for a secondary battery is dispersed, and then apply the slurry. ⁇ It was common to prepare a mixture sheet for a secondary battery by drying. In this case, a solvent that dissolves the binder is used.
• solvents capable of dissolving binder resins that have been generally used in the past are limited to specific solvents such as butyl butyrate.
• the content of the liquid medium in the secondary battery mixture of the present disclosure is preferably 1% by mass or less. Also in the raw material composition, the content of the liquid medium is preferably 1% by mass or less.
• the secondary battery mixture of the present disclosure has a binder having a fibrous structure as a constituent element in forming a secondary battery mixture containing a sulfide-based electrolyte.
• the binder is fibrillated.
• the fibrillated binder is present in the secondary battery mixture, and acts to bind the powders of the components constituting the secondary battery mixture. is achieved. That is, the present disclosure uses a fibrillar resin as a binder, and the binder in the secondary battery mixture has a fiber structure, so that the secondary battery mixture has good properties. and found that a mixture sheet containing the same can be obtained, thereby completing the present disclosure.
• the binder in the secondary battery mixture preferably has a fibrous structure with a fibril diameter (median value) of 100 nm or less.
• the presence of the binder having a small fibril diameter in the secondary battery mixture has the effect of further binding the powders of the components constituting the secondary battery mixture.
• the binder is finely fibrillated so that the binder has a fibrous structure with a fibril diameter (median value) of 100 nm or less.
• a fibril diameter median value
• deterioration of the oxide-based solid electrolyte can be further reduced, and good performance can be exhibited.
• the above fibril diameter is a value measured by the following method. (1) Using a scanning electron microscope (Model S-4800, manufactured by Hitachi, Ltd.), an enlarged photograph (7000 times) of the mixture sheet for a secondary battery is taken to obtain an image. (2) Draw two lines on this image at equal intervals in the horizontal direction to divide the image into three equal parts. (3) For all fibrillated binders on the upper straight line, measure the diameter at three locations per fibrillated binder, and take the average value as the diameter of the fibrillated binder. do. The three points to be measured are the points of intersection between the fibrillated binder and the straight line, and the points shifted vertically by 0.5 ⁇ m from the points of intersection. (Except primary particles of non-fiberized binder).
• the fibril diameter (median value) is preferably 100 nm or less, more preferably 85 nm or less, and even more preferably 70 nm or less. It should be noted that excessive fibrillation tends to result in loss of flexibility. Although the lower limit is not particularly limited, it is preferably 15 nm or more, more preferably 20 nm or more, and particularly preferably 31 nm or more from the viewpoint of strength.
• Step (1) of applying a shearing force while mixing a raw material composition containing a sulfide-based solid electrolyte and a binder powder.
• a method performed by step (3) can be mentioned.
• step (1) by setting the mixing conditions of the raw material composition to 3000 rpm or less, fibrillation of the binder can be advanced while maintaining the flexibility, and the shear applied can be reduced.
• the fibril diameter (median value) of the binder can be 100 nm or less.
• step (4) of applying a larger load to the obtained rolled sheet and rolling it into a thinner sheet after the step (3). It is also preferred to repeat step (4). Further, after step (3) or step (4), the obtained rolled sheet is coarsely crushed, then bulk-formed again and rolled into a sheet (5) to adjust the fibril diameter. can do. It is preferable to repeat step (5), for example, 1 to 12 times.
• the binder powder is fibrillated, and by entangling it with the powder component such as the sulfide-based solid electrolyte, a mixture for a secondary battery can be produced.
• the said manufacturing method is mentioned later.
• binder powder means a solid state as powder, not a dispersed state mixed with a liquid medium.
• the object of the present disclosure can be suitably achieved by producing a mixture for a secondary battery by using the binder in such a state and using the binder in the absence of the liquid medium.
• the powdery fibrillar resin which is a raw material for preparing the secondary battery mixture of the present disclosure, preferably has a water content of 500 ppm or less.
• a water content of 500 ppm or less is preferable in terms of reducing deterioration of the sulfide-based solid electrolyte. More preferably, the water content is 300 ppm or less.
• a fibrillar resin indicates a resin that readily fibrillates when shear stress is applied.
• the fibrillated resin entangles with other powder components, etc., thereby binding the powder components, thereby making it easier to mold the powder components.
• It can act as a binder.
• fibrillar resins include liquid crystal polymer (LCP), cellulose, acrylic resin, ultra-high molecular weight polyethylene, PTFE, etc.
• LCP liquid crystal polymer
• cellulose acrylic resin
• PTFE ultra-high molecular weight polyethylene
• PTFE is preferable in terms of chemical stability, thermal stability and workability. is.
• the PTFE is not particularly limited, and may be a homopolymer or a copolymer that can be fibrillated.
• fluorine atom-containing monomers that are comonomers include chlorotrifluoroethylene, hexafluoropropylene, fluoroalkylethylene, perfluoroalkylethylene, fluoroalkyl-fluorovinyl ether, and the like.
• the powdered PTFE preferably has a standard specific gravity of 2.12 to 2.20.
• a standard specific gravity within this range is advantageous in that a high-strength mixture sheet can be produced. More preferably, the lower limit of the standard specific gravity is 2.13 or more.
• the upper limit of the standard specific gravity is more preferably 2.19 or less, even more preferably 2.18 or less.
• the powdery PTFE preferably contains 50% by mass or more, more preferably 80% by mass or more, of a polytetrafluoroethylene resin having a secondary particle size of 450 ⁇ m or more.
• a polytetrafluoroethylene resin having a secondary particle size of 450 ⁇ m or more.
• the lower limit of the average secondary particle size of the powdery PTFE is more preferably 450 ⁇ m, and still more preferably 500 ⁇ m.
• the upper limit of the secondary particle size is more preferably 700 ⁇ m or less, and even more preferably 600 ⁇ m or less.
• the secondary particle size can be determined by, for example, a sieving method.
• the powdery PTFE preferably has an average primary particle size of 150 nm or more, since a mixture sheet having higher strength and excellent homogeneity can be obtained. It is more preferably 180 nm or more, still more preferably 210 nm or more, and particularly preferably 220 nm or more.
• the upper limit is not particularly limited, it may be 500 nm. From the viewpoint of productivity in the polymerization step, the upper limit is preferably 350 nm.
• the average primary particle size is calculated by using an aqueous dispersion of PTFE obtained by polymerization and adjusting the polymer concentration to 0.22% by mass. Create a calibration curve with the average primary particle diameter determined by measuring the directional diameter in the electron micrograph, measure the transmittance of the aqueous dispersion to be measured, and determine based on the calibration curve. can.
• PTFE for use in the present disclosure may have a core-shell structure.
• PTFE having a core-shell structure includes, for example, polytetrafluoroethylene comprising a core of high molecular weight polytetrafluoroethylene and a shell of lower molecular weight polytetrafluoroethylene or modified polytetrafluoroethylene in the particles.
• modified polytetrafluoroethylene include polytetrafluoroethylene described in JP-T-2005-527652.
• PTFE in powder form that satisfies the above parameters can be obtained by a conventional manufacturing method.
• it may be produced following the production methods described in International Publication No. 2015-080291, International Publication No. 2012-086710, and the like.
• the lower limit of the binder content in the solid secondary battery mixture is preferably 0.2% by mass or more, more preferably 0.3% by mass or more. More preferably, it exceeds 0.5% by mass.
• the upper limit of the content of the binder in the solid secondary battery mixture is preferably 10% by mass or less, more preferably 7% by mass or less, particularly preferably 6% by mass or less, and still more preferably. is 4% by mass or less, more preferably 1.7% by mass or less, and most preferably 1.0% by mass or less. If the binder is within the above range, it is possible to form a self-supporting sheet with excellent handleability while suppressing an increase in electrode resistance.
• the solid electrolyte used in the solid secondary battery mixture of the present disclosure is a sulfide-based solid electrolyte.
• the use of a sulfide-based solid electrolyte has the advantage of flexibility.
• Examples of sulfide-based solid electrolytes include lithium ion conductive inorganic solid electrolytes that satisfy the composition represented by the following formula (1).
• Li a1 M b1 P c1 S d1 A e1 (1)
• M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, Ti and Ge.
• A represents an element selected from I, Br, Cl and F;
• a1 to e1 indicate the composition ratio of each element, and a1:b1:c1:d1:e1 satisfies 1-12:0-5:1:2-12:0-10.
• a1 is preferably 1 to 9, more preferably 1.5 to 7.5.
• b1 is preferably 0-3, more preferably 0-1.
• d1 is preferably 2.5 to 10, more preferably 3.0 to 8.5.
• e1 is preferably 0 to 5, more preferably 0 to 3.
• the sulfide-based solid electrolyte preferably contains lithium.
• a sulfide-based solid electrolyte containing lithium is used in a solid battery using lithium ions as a carrier, and is particularly preferable in terms of an electrochemical device having a high energy density.
• composition ratio of each element can be controlled by adjusting the compounding amount of the raw material compound when producing the sulfide-based inorganic solid electrolyte, as described below.
• the sulfide-based inorganic solid electrolyte may be amorphous (glass), crystallized (glass-ceramics), or only partially crystallized.
• glass glass
• glass-ceramics glass-ceramics
• Li--P--S type glass containing Li, P and S, or Li--P--S type glass ceramics containing Li, P and S can be used.
• Sulfide-based inorganic solid electrolytes include, for example, lithium sulfide (Li 2 S), phosphorus sulfide (e.g., diphosphorus pentasulfide (P 2 S 5 )), elemental phosphorus, elemental sulfur, sodium sulfide, hydrogen sulfide, lithium halide (e.g., LiI, LiBr, LiCl) and sulfides of the element represented by M above (eg, SiS 2 , SnS, GeS 2 ) can be produced by reacting at least two raw materials.
• Li 2 S lithium sulfide
• phosphorus sulfide e.g., diphosphorus pentasulfide (P 2 S 5 )
• elemental phosphorus e.g., elemental sulfur
• sodium sulfide sodium sulfide
• hydrogen sulfide e.g., lithium halide
• Li 2 SP 2 S 5 —LiCl Li 2 SP 2 S 5 —H 2 S, Li 2 SP 2 S 5 —H 2 S—LiCl, Li 2 S—LiI—P 2 S 5 , Li 2 S—LiI—Li 2 OP 2 S 5 , Li 2 S—LiBr—P 2 S 5 , Li 2 S—Li 2 OP 2 S 5 , Li 2 S—Li 3 PO 4 — P2S5 , Li2SP2S5 - P2O5 , Li2SP2S5 - SiS2 , Li2SP2S5 - SiS2 - LiCl , Li2SP 2S5 - SnS , Li2SP2S5 - Al2S3 , Li2S - GeS2 , Li2S - GeS2 -ZnS, Li2S - Ga2S
• the sulfide-based solid electrolyte is preferably a sulfide-based solid electrolyte that satisfies the composition represented by the following formula (A).
• A aLi 2 S-bX 1 S 2 -cLiX 2 -(1-abc)P 2 S 5 (A) (where 0.6 ⁇ a ⁇ 0.86, 0 ⁇ b ⁇ 0.333, 0 ⁇ c ⁇ 0.3, 0.05 ⁇ b + c ⁇ 0.4, X 1 is Ge, Sn, Ti or Si, X2 represents Cl, Br or I, provided that either b or c is not 0)
• a sulfide-based solid electrolyte that satisfies the composition represented by the above formula (A) is advantageous in that high ionic conductivity can be stably obtained.
• sulfide-based solid electrolyte represented by the above formula (A) include 0.714Li 2 S-0.143SnS 2 -0.143P 2 S 5 (Li 10 SnP 2 S 12 (LSPS)) , 0.625Li 2 S-0.25LiCl-0.125P 2 S 5 (Li 6 PS 5 Cl (LPSCl)), 0.715Li 2 S-0.143GeS2-0.142P 2 S 5 (Li 10 GeP 2 S 12 (LGPS)), etc., or a mixture of two or more types can be used.
• the average particle size of the sulfide-based solid electrolyte is preferably 0.1 ⁇ m or more and 20 ⁇ m or less.
• the upper limit is more preferably 0.2 ⁇ m or more, and still more preferably 0.3 ⁇ m or more.
• the upper limit is more preferably 18 ⁇ m or less, and even more preferably 15 ⁇ m or less. If the average particle size of the sulfide-based solid electrolyte is less than 0.1 ⁇ m, it may be difficult to handle the powder. On the other hand, when the average particle size of the sulfide-based solid electrolyte exceeds 20 ⁇ m, the press formability may deteriorate.
• the average particle size of the sulfide-based solid electrolyte particles is measured according to the following procedure.
• the sulfide-based solid electrolyte particles are diluted with water (heptane in the case of water-labile substances) to prepare a 1% by mass dispersion in a 20-ml sample bottle.
• the dispersed sample after dilution is irradiated with ultrasonic waves of 1 kHz for 10 minutes and used for the test immediately after that.
• ultrasonic waves 1 kHz for 10 minutes
• JIS Z8828:2013 "Particle Size Analysis-Dynamic Light Scattering Method" as necessary. Five samples are prepared for each level and the average value is adopted.
• the method for adjusting the average particle size of the sulfide solid electrolyte is not particularly limited, it is carried out, for example, as follows.
• a known grinder or classifier is used.
• a mortar, sand mill, ball mill, jet mill or sieve is preferably used.
• a solvent such as water or ethanol may be added during pulverization.
• Classification is preferably carried out in order to obtain a desired particle size. Classification is not particularly limited, and can be performed using a sieve, an air classifier, or the like.
• the content of the sulfide-based solid electrolyte in the solid component in the secondary battery mixture is 100 solid components when considering the reduction of interfacial resistance when used in a solid secondary battery and the maintenance of the reduced interfacial resistance.
• % by mass in the electrode, it is preferably 5% by mass or more, more preferably 9% by mass or more, and particularly preferably 12% by mass or more.
• the upper limit is preferably 60% by mass or less, more preferably 50% by mass or less, and particularly preferably 40% by mass or less.
• the content is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.
• the upper limit is preferably 99.9% by mass or less, more preferably 99.8% by mass or less, and particularly preferably 99.7% by mass or less.
• the sulfide-based solid electrolytes may be used singly or in combination of two or more.
• the solid content refers to a component that does not disappear by volatilization or evaporation when drying treatment is performed at 170° C. for 6 hours in a nitrogen atmosphere.
• the secondary battery mixture of the present disclosure is particularly suitable for lithium ion solid state secondary batteries.
• the secondary battery mixture of the present disclosure is usually used in a sheet form when used in a solid secondary battery.
• the secondary battery mixture sheet of the present disclosure can be used as a positive electrode sheet or can be used as a negative electrode sheet. Further, it can be a sheet for a solid electrolyte layer. Among these, the electrode sheet further contains active material particles. The active material particles can be used as a positive electrode active material or a negative electrode active material. The secondary battery mixture sheet of the present disclosure can be more suitably used as a positive electrode sheet using a positive electrode active material. Moreover, when setting it as an electrode sheet, you may contain a conductive support agent as needed.
• Electrode active materials are described below.
• the secondary battery mixture sheet of the present disclosure contains a positive electrode active material.
• a positive electrode active material known as a positive electrode active material for solid batteries can be applied.
• the positive electrode active material is not particularly limited as long as it can electrochemically occlude and release alkali metal ions.
• a material containing an alkali metal and at least one transition metal is preferable.
• Specific examples include alkali metal-containing transition metal composite oxides, alkali metal-containing transition metal phosphate compounds, conductive polymers, and the like.
• an alkali metal-containing transition metal composite oxide that produces a high voltage is particularly preferable.
• the alkali metal ions include lithium ions, sodium ions, and potassium ions.
• the alkali metal ions may be lithium ions. That is, in this aspect, the alkali metal ion secondary battery is a lithium ion secondary battery.
• alkali metal-containing transition metal composite oxide examples include: Formula: M a Mn 2-b M 1 b O 4 (Wherein, M is at least one metal selected from the group consisting of Li, Na and K; 0.9 ⁇ a; 0 ⁇ b ⁇ 1.5; M 1 is Fe, Co, Ni, at least one metal selected from the group consisting of Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si and Ge) and manganese spinel composite oxide, Formula: MNi 1-c M 2 cO 2 (wherein M is at least one metal selected from the group consisting of Li, Na and K; 0 ⁇ c ⁇ 0.5; M2 is Fe, Co, Mn, Cu, Zn, Al, at least one metal selected from the group consisting of Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si and Ge), or Formula: MCo 1-d M 3 d O 2 (Wherein, M is at least one metal selected from the group consisting
• MCoO 2 , MMnO 2 , MNiO 2 , MMn 2 O 4 , MNi 0.8 Co 0.15 Al 0.05 O 2 , or MNi 1/3 Co 1/3 Mn 1/3 O 2 and the like are preferable, and compounds represented by the following general formula (3) are preferable.
• M is at least one metal selected from the group consisting of Li, Na and K
• alkali metal-containing transition metal phosphate compound for example, the following formula (4) M e M 4 f (PO 4 ) g (4) (wherein M is at least one metal selected from the group consisting of Li, Na and K, and M4 is selected from the group consisting of V, Ti, Cr, Mn, Fe, Co, Ni and Cu 0.5 ⁇ e ⁇ 3, 1 ⁇ f ⁇ 2, 1 ⁇ g ⁇ 3).
• M is preferably one metal selected from the group consisting of Li, Na and K, more preferably Li or Na, still more preferably Li.
• the transition metal of the lithium-containing transition metal phosphate compound is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. Specific examples include LiFePO 4 and Li 3 Fe 2 (PO 4 ). 3 , iron phosphates such as LiFeP 2 O 7 , cobalt phosphates such as LiCoPO 4 , and some of the transition metal atoms that are the main component of these lithium transition metal phosphate compounds are Al, Ti, V, Cr, Mn , Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si, and the like.
• the lithium-containing transition metal phosphate compound preferably has an olivine structure.
• positive electrode active materials include MFePO4 , MNi0.8Co0.2O2 , M1.2Fe0.4Mn0.4O2 , MNi0.5Mn1.5O2 and MV3 .
• M 2 MnO 3 (wherein M is at least one metal selected from the group consisting of Li, Na and K) and the like.
• positive electrode active materials such as M 2 MnO 3 and MNi 0.5 Mn 1.5 O 2 are used even when the secondary battery is operated at a voltage exceeding 4.4 V or at a voltage of 4.6 V or higher. , is preferable in that the crystal structure does not collapse.
• an electrochemical device such as a secondary battery using a positive electrode material containing the above-exemplified positive electrode active material is less likely to decrease in remaining capacity and less likely to change in resistance increase rate even when stored at high temperature. It is preferable because the battery performance does not deteriorate even if it is operated with a voltage.
• positive electrode active materials include M 2 MnO 3 and MM 6 O 2 (wherein M is at least one metal selected from the group consisting of Li, Na and K, M 6 is Co, Ni , transition metals such as Mn and Fe), and the like.
• Examples of the solid solution material include alkali metal manganese oxide represented by the general formula Mx[Mn (1-y) M 7 y ]O 2 .
• M in the formula is at least one metal selected from the group consisting of Li, Na and K
• M 7 consists of at least one metal element other than M and Mn, such as Co, Ni , Fe, Ti, Mo, W, Cr, Zr and Sn.
• the values of x, y, and z in the formula are in the ranges of 1 ⁇ x ⁇ 2, 0 ⁇ y ⁇ 1, and 1.5 ⁇ z ⁇ 3.
• a manganese - containing solid solution material such as Li1.2Mn0.5Co0.14Ni0.14O2 , in which LiNiO2 or LiCoO2 is dissolved based on Li2MnO3 has a high energy density. It is preferable from the point that an alkali metal ion secondary battery can be provided.
• lithium phosphate in the positive electrode active material because the continuous charging characteristics are improved.
• the use of lithium phosphate is not limited, it is preferable to use a mixture of the positive electrode active material and lithium phosphate.
• the lower limit of the amount of lithium phosphate used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and still more preferably 0.5% by mass, based on the total of the positive electrode active material and lithium phosphate. % or more, and the upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less.
• Examples of the conductive polymer include p-doping type conductive polymer and n-doping type conductive polymer.
• Examples of conductive polymers include polyacetylene-based, polyphenylene-based, heterocyclic polymers, ionic polymers, ladder and network polymers, and the like.
• the above positive electrode active material may be used in which a material having a different composition is attached to the surface of the positive electrode active material.
• Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, oxides such as bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, and calcium sulfate.
• sulfates such as aluminum sulfate
• carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate, and carbon.
• These surface-adhering substances are, for example, dissolved or suspended in a solvent and impregnated or added to the positive electrode active material, followed by drying; After impregnating and adding to the substance, it can be attached to the surface of the positive electrode active material by a method of reacting by heating or the like, a method of adding to the positive electrode active material precursor and baking at the same time, or the like.
• a method of mechanically depositing carbonaceous matter in the form of activated carbon or the like later can also be used.
• the lower limit is preferably 0.1 ppm or more, more preferably 1 ppm or more, and still more preferably 10 ppm or more, and the upper limit is preferably 20% or less, more preferably 20% or less, by mass relative to the positive electrode active material. is used at 10% or less, more preferably 5% or less.
• the surface-adhering substance can suppress the oxidation reaction of the solid electrolyte on the surface of the positive electrode active material, thereby improving the battery life. If the amount of adhesion is too small, the effect is not sufficiently exhibited, and if it is too large, the resistance may increase due to hindrance to the entry and exit of lithium ions.
• the shape of the particles of the positive electrode active material includes conventionally used lumps, polyhedrons, spheres, ellipsoids, plates, needles, columns, and the like. Also, the primary particles may aggregate to form secondary particles.
• the tap density of the positive electrode active material is preferably 0.5 g/cm 3 or more, more preferably 0.8 g/cm 3 or more, and still more preferably 1.0 g/cm 3 or more. If the tap density of the positive electrode active material is less than the above lower limit, the amount of dispersion medium required for forming the positive electrode active material layer increases, and the required amount of the conductive material and the binder increases, and the positive electrode to the positive electrode active material layer increases. In some cases, the filling rate of the active material is restricted, and the battery capacity is restricted.
• a high-density positive electrode active material layer can be formed by using a composite oxide powder with a high tap density. Generally, the higher the tap density, the better, and there is no particular upper limit.
• the upper limit is preferably 4.0 g/cm 3 or less, more preferably 3.7 g/cm 3 or less, still more preferably 3.5 g/cm 3 or less.
• the tap density is the powder filling density (tap density) g/cm 3 when 5 to 10 g of the positive electrode active material powder is placed in a 10 ml glass graduated cylinder and tapped 200 times with a stroke of about 20 mm. Ask as
• the median diameter d50 of the particles of the positive electrode active material is preferably 0.3 ⁇ m or more, more preferably 0.5 ⁇ m or more, and even more preferably 0.5 ⁇ m or more. is 0.8 ⁇ m or more, most preferably 1.0 ⁇ m or more, and is preferably 30 ⁇ m or less, more preferably 27 ⁇ m or less, even more preferably 25 ⁇ m or less, and most preferably 22 ⁇ m or less. If the lower limit is not reached, it may not be possible to obtain a product with high tap density.
• the diffusion of lithium in the particles takes time, resulting in a decrease in battery performance or the creation of the positive electrode of the battery, that is, the active material.
• the active material that is, the active material.
• a conductive material, binder, or the like is slurried with a solvent and applied as a thin film, problems such as streaks may occur.
• by mixing two or more kinds of positive electrode active materials having different median diameters d50 it is possible to further improve the filling property during the production of the positive electrode.
• the median diameter d50 is measured by a known laser diffraction/scattering particle size distribution analyzer.
• HORIBA's LA-920 is used as a particle size distribution analyzer
• a 0.1% by mass sodium hexametaphosphate aqueous solution is used as a dispersion medium for measurement, and a measurement refractive index of 1.24 is set after ultrasonic dispersion for 5 minutes. measured as
• the average primary particle size of the positive electrode active material is preferably 0.05 ⁇ m or more, more preferably 0.1 ⁇ m or more, and still more preferably 0.1 ⁇ m or more. It is 2 ⁇ m or more, and the upper limit is preferably 5 ⁇ m or less, more preferably 4 ⁇ m or less, even more preferably 3 ⁇ m or less, and most preferably 2 ⁇ m or less. If the above upper limit is exceeded, it is difficult to form spherical secondary particles, which adversely affects the powder filling property, and the specific surface area is greatly reduced, so the battery performance such as output characteristics is likely to deteriorate. Sometimes. Conversely, below the above lower limit, problems such as poor reversibility of charge/discharge may occur due to underdevelopment of crystals.
• the average primary particle size of the positive electrode active material is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification of 10,000 times, the maximum value of the intercept of the left and right boundary lines of the primary particles with respect to the horizontal straight line is obtained for arbitrary 50 primary particles, and the average value is obtained. be done.
• SEM scanning electron microscope
• the BET specific surface area of the positive electrode active material is preferably 0.1 m 2 /g or more, more preferably 0.2 m 2 /g or more, still more preferably 0.3 m 2 /g or more, and the upper limit is preferably 50 m 2 /g. g or less, more preferably 40 m 2 /g or less, and even more preferably 30 m 2 /g or less. If the BET specific surface area is smaller than this range, the battery performance tends to deteriorate.
• the BET specific surface area is measured using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken Co., Ltd.). It is defined as a value measured by the nitrogen adsorption BET one-point method by the gas flow method using a nitrogen-helium mixed gas accurately adjusted so that the value of the relative pressure of nitrogen to the atmospheric pressure is 0.3.
• the particles of the positive electrode active material are mainly secondary particles.
• the positive electrode active material particles preferably contain 0.5 to 7.0% by volume of fine particles having an average secondary particle size of 40 ⁇ m or less and an average primary particle size of 1 ⁇ m or less.
• a method for producing the positive electrode active material a general method for producing an inorganic compound is used.
• various methods are conceivable for producing spherical or ellipsoidal active materials.
• a transition metal raw material is dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring.
• a Li source such as LiOH, Li 2 CO 3 , LiNO 3 is added and sintered at a high temperature to obtain an active material. .
• the above positive electrode active materials may be used alone, or two or more of different compositions may be used together in any combination or ratio.
• Preferred combinations in this case include a combination of LiCoO 2 and a ternary system such as LiNi 0.33 Co 0.33 Mn 0.33 O 2 , LiCoO 2 and LiMn 2 O 4 or a portion of this Mn
• a combination of one substituted with a transition metal or the like, or a combination of LiFePO 4 and LiCoO 2 or a combination of a part of this Co substituted with another transition metal or the like can be mentioned.
• the content of the positive electrode active material is preferably 40% by mass or more, more preferably 50% by mass or more, and particularly preferably 60% by mass or more.
• the upper limit is preferably 94.8% by mass or less, more preferably 90.5% by mass or less, and particularly preferably 87.5% by mass or less. If the content of the positive electrode active material in the positive electrode mixture is low, the electric capacity may become insufficient. Conversely, if the content is too high, the electron/ion conductivity and strength of the positive electrode may be insufficient.
• the negative electrode active material is not particularly limited, and examples thereof include lithium metal, artificial graphite, graphite carbon fiber, resin baked carbon, pyrolytic vapor growth carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin baked carbon. , polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite and those containing carbonaceous materials such as non-graphitizable carbon, silicon-containing compounds such as silicon and silicon alloys, Li 4 Ti 5 O 12 , etc. Either selected or a mixture of two or more types can be mentioned. Among them, those containing carbonaceous material at least in part and silicon-containing compounds can be particularly preferably used.
• the content of the negative electrode active material is preferably 40% by mass or more, more preferably 50% by mass or more, and particularly preferably 60% by mass or more.
• the upper limit is preferably 94.8% by mass or less, more preferably 90.5% by mass or less, and particularly preferably 87.5% by mass or less. If the content of the negative electrode active material in the negative electrode mixture is low, the electric capacity may become insufficient. Conversely, if the content is too high, the electron/ion conductivity and strength of the negative electrode may be insufficient.
• Conductivity aid Any known conductive material can be used as the conductive aid. Specific examples include metal materials such as copper and nickel, graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black and thermal black, and needle coke. , carbon nanotubes, fullerenes, and amorphous carbon such as VGCF. In addition, these may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.
• the conductive aid When using a conductive aid, the conductive aid is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.5% by mass or more in the electrode active material layer, In addition, it is used so that it is usually contained in an amount of 50% by mass or less, preferably 30% by mass or less, more preferably 15% by mass or less. If the content is lower than this range, the electrical conductivity may be insufficient. Conversely, if the content is higher than this range, the battery capacity may decrease.
• the secondary battery mixture sheet may further contain a thermoplastic resin.
• thermoplastic resins include vinylidene fluoride, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, and polyethylene oxide. One type may be used alone, or two or more types may be used together in any combination and ratio.
• the ratio of the thermoplastic resin to the electrode active material is usually 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.10% by mass or more, and is usually 3.0% by mass or less, The range is preferably 2.5% by mass or less, more preferably 2.0% by mass or less.
• the content of the binder is usually 0.2% by mass or more, preferably 0.3% by mass, as the ratio of the binder in the secondary battery mixture sheet. % or more, more preferably 0.5 mass % or more, and usually 10 mass % or less, preferably 6.0 mass % or less, further preferably 4 mass % or less, and even more preferably 1.0 mass % or less. It is 7% by mass or less, and most preferably 1.0% by mass or less. If the ratio of the binder is too low, the active material cannot be sufficiently retained in the secondary battery mixture sheet, resulting in insufficient mechanical strength of the secondary battery mixture sheet and deterioration of battery performance such as cycle characteristics. It may let you. On the other hand, if it is too high, it may lead to a decrease in battery capacity and conductivity.
• the manufacturing method of the mixture sheet for a secondary battery of the present disclosure uses a raw material composition obtained by mixing the components described above and forming the composition into a sheet. Since the drying process can be omitted in the sheet formation, the amount of liquid medium used is reduced or not used at all, and a shear stress is applied to the powdery raw material composition without preparing a slurry. is preferred. Also, a small amount of solvent may be added as a lubricant in order to reduce the load on the device.
• the solvent is preferably an organic solvent, and the content of the solvent is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less, relative to the raw material composition.
• the secondary battery mixture sheet of the present disclosure is Step (1) of applying a shearing force while mixing a raw material composition containing an oxide-based solid electrolyte and a binder A step (2) of forming the secondary battery mixture obtained in the step (1) into a bulk shape, and rolling the bulk secondary battery mixture obtained in the step (2) into a sheet. Step (3) It can be obtained by a method for producing a secondary battery mixture sheet having.
• the resulting mixture for a secondary battery is determined by simply mixing an oxide-based solid electrolyte, a binder, and the like. It exists in an intangible state.
• Specific mixing methods include W-type mixers, V-type mixers, drum-type mixers, ribbon mixers, conical screw-type mixers, single-screw kneaders, twin-screw kneaders, mix mullers, agitating mixers, and planeters.
• a method of mixing using a Lee mixer, a Henschel mixer, a high-speed mixer, or the like can be mentioned.
• the mixing conditions may be appropriately set in terms of rotation speed and mixing time.
• the number of revolutions is preferably 15000 rpm or less.
• the range is preferably 10 rpm or more, more preferably 1000 rpm or more, still more preferably 3000 rpm or more, and preferably 12000 rpm or less, more preferably 11000 rpm or less, still more preferably 10000 rpm. If it falls below the above range, it takes time for mixing, which affects productivity. On the other hand, if the
• step (1) is preferably carried out at 30° C. or higher, more preferably 60° C. or higher. Moreover, it is preferable to include a step (A) of mixing the raw material composition and dispersing the binder before the step (1). In step (A) above, it is preferable to mix with as little shearing force as possible.
• mixing conditions may be appropriately set such as rotation speed and mixing time.
• the number of rotations is preferably 500 rpm or less. It is preferably 20 rpm or more, more preferably 30 rpm or more, still more preferably 40 rpm or more, and is preferably 400 rpm or less, more preferably 300 rpm or less, still more preferably 200 rpm.
• the mixing temperature is preferably 19° C. or lower. By setting such a temperature range, it is possible to process the material into a desired sheet shape in a shorter time.
• PTFE has two transition temperatures at about 19°C and about 30°C. Below 19°C, PTFE can be easily mixed while maintaining its shape. However, above 19°C, the structure of the PTFE particles becomes looser and more sensitive to mechanical shear. At temperatures above 30° C., a higher degree of fibrillation occurs.
• the raw material composition preferably contains substantially no liquid medium, and is preferably powder.
• the content of the liquid medium in the raw material composition, which is powder, is preferably 1% by mass or less.
• the above step (A) is preferably carried out at a temperature of 19°C or less, preferably 0°C to 19°C. That is, in such step (A), it is preferable to mix and homogenize without causing fibrillation. Then, it is preferable to fibrillate by subsequent steps (1) to (5).
• forming into a bulk shape means that the secondary battery mixture is made into one mass.
• Specific methods for bulk molding include extrusion molding and press molding.
• the term "bulk” does not have a specific shape, and may be in the form of a mass, and includes rods, sheets, spheres, cubes, and the like.
• the diameter of the cross section or the minimum side is 10000 ⁇ m or more. More preferably, it is 20000 ⁇ m or more.
• a specific rolling method in the step (3) includes a method of rolling using a roll press machine, a plate press machine, a calender roll machine, or the like.
• step (4) of applying a larger load to the obtained rolled sheet and rolling it into a thinner sheet after the step (3). It is also preferred to repeat step (4). In this way, the rolling sheet is not thinned all at once, but is gradually rolled in stages to achieve better flexibility.
• the number of times of step (4) is preferably 2 or more and 10 or less, more preferably 3 or more and 9 or less.
• a specific rolling method includes, for example, a method in which two or a plurality of rolls are rotated and a rolled sheet is passed between them to form a thinner sheet.
• the rolled sheet may be coarsely crushed, then bulk-formed again, and rolled into a sheet (5). preferable. It is also preferred to repeat step (5).
• the number of times of step (5) is preferably 1 time or more and 12 times or less, more preferably 2 times or more and 11 times or less.
• step (5) specific methods for crushing the rolled sheet and forming it into bulk include a method of folding the rolled sheet, a method of forming it into a rod or a thin film sheet, a method of chipping, and the like.
• crushing means changing the form of the rolled sheet obtained in step (3) or step (4) into another form in order to roll it into a sheet in the next step. It also includes the case of simply folding a rolled sheet.
• step (4) may be performed after step (5), or may be performed repeatedly.
• uniaxial stretching or biaxial stretching may be carried out in steps (2) to (3), (4) and (5).
• the fibril diameter (median value) can also be adjusted by the degree of coarse grinding in step (5).
• Steps (2) to (5) are preferably carried out at 30°C or higher, more preferably 60°C or higher.
• the rolling reduction is preferably 10% or more, more preferably 20% or more, preferably 80% or less, more preferably 65% or less, and further The range is preferably 50% or less. If it is less than the above range, it takes time as the number of rolling increases, which affects productivity. On the other hand, if it exceeds, fibrillation may proceed excessively, resulting in a mixture sheet having inferior strength and flexibility.
• the rolling rate refers to the reduction rate of the thickness of the sample after rolling with respect to the thickness of the sample before rolling.
• the sample before rolling may be a bulk mixture or a sheet mixture.
• the thickness of a sample refers to the thickness in the direction in which a load is applied during rolling.
• PTFE powder is fibrillated by applying a shearing force.
• a fibrous structure with a fibril diameter (median value) of 100 nm or less excessive shear stress may excessively promote fibrillation and impair flexibility.
• weak shear stress may not be sufficient in terms of strength.
• the fibril diameter (median ) can have a fibrous structure of 100 nm or less.
• the secondary battery mixture sheet of the present disclosure can be either a positive electrode sheet or a negative electrode sheet. Further, it can be a sheet for a solid electrolyte layer. When a positive electrode mixture sheet or a negative electrode sheet is produced, the positive electrode active material or negative electrode active material may be mixed together with the solid electrolyte and the binder in the production of the secondary battery mixture sheet.
• the positive electrode is preferably composed of a current collector and the positive electrode sheet.
• materials for the positive electrode current collector include metals such as aluminum, titanium, tantalum, stainless steel and nickel, and metal materials such as alloys thereof; and carbon materials such as carbon cloth and carbon paper. Among them, metal materials, particularly aluminum or alloys thereof, are preferred.
• the shape of the current collector examples include metal foil, metal cylinder, metal coil, metal plate, expanded metal, punch metal, foam metal, etc. in the case of metal materials, and carbon plate, carbon thin film, carbon thin film, carbon A cylinder etc. are mentioned. Among these, metal foil is preferred. Note that the metal foil may be appropriately formed in a mesh shape. Although the thickness of the metal foil is arbitrary, it is usually 1 ⁇ m or more, preferably 3 ⁇ m or more, more preferably 5 ⁇ m or more, and usually 1 mm or less, preferably 100 ⁇ m or less, more preferably 50 ⁇ m or less. If the metal foil is thinner than this range, the strength required as a current collector may be insufficient. Conversely, if the metal foil is thicker than this range, the handleability may be impaired.
• the surface of the current collector is coated with a conductive aid from the viewpoint of reducing the electrical contact resistance between the current collector and the positive electrode material mixture sheet.
• conductive aids include carbon and noble metals such as gold, platinum, and silver.
• the production of the positive electrode may be carried out according to a conventional method. For example, a method of laminating the positive electrode sheet and the current collector via an adhesive and drying the laminate can be used.
• the density of the positive electrode sheet is preferably 2.0 g/cm 3 or more, more preferably 2.1 g/cm 3 or more, still more preferably 2.3 g/cm 3 or more, and preferably 4.0 g/cm 3 or more. 3 or less, more preferably 3.9 g/cm 3 or less, and still more preferably 3.8 g/cm 3 or less. If this range is exceeded, the conductivity between the active materials will decrease, the battery resistance will increase, and high output may not be obtained. If it is less than that, the content of the hard and fragile active material may be low, resulting in a battery with low capacity.
• the thickness of the positive electrode is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the mixture sheet after subtracting the thickness of the current collector is preferably 10 ⁇ m as the lower limit with respect to one side of the current collector. Above, it is more preferably 20 ⁇ m or more, more preferably 500 ⁇ m or less, more preferably 450 ⁇ m or less.
• the positive electrode having a different composition adhered to the surface of the positive electrode may be used.
• Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, oxides such as bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, and calcium sulfate.
• oxides such as bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, and calcium sulfate.
• sulfates such as aluminum sulfate
• carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate, and carbon.
• the negative electrode is preferably composed of a current collector and the negative electrode sheet.
• Materials for the negative electrode current collector include metals such as copper, nickel, titanium, tantalum, and stainless steel, and metal materials such as alloys thereof; and carbon materials such as carbon cloth and carbon paper. Among them, metal materials, particularly copper, nickel, or alloys thereof are preferred.
• the shape of the current collector examples include metal foil, metal cylinder, metal coil, metal plate, expanded metal, punch metal, foam metal, etc. in the case of metal materials, and carbon plate, carbon thin film, carbon thin film, carbon A cylinder etc. are mentioned. Among these, metal foil is preferred. Note that the metal foil may be appropriately formed in a mesh shape. Although the thickness of the metal foil is arbitrary, it is usually 1 ⁇ m or more, preferably 3 ⁇ m or more, more preferably 5 ⁇ m or more, and usually 1 mm or less, preferably 100 ⁇ m or less, more preferably 50 ⁇ m or less. If the metal foil is thinner than this range, the strength required as a current collector may be insufficient. Conversely, if the metal foil is thicker than this range, the handleability may be impaired.
• the production of the negative electrode may be carried out according to a conventional method.
• a method of laminating the negative electrode sheet and the current collector with an adhesive interposed therebetween and drying the laminate can be used.
• the density of the negative electrode sheet is preferably 1.3 g/cm 3 or more, more preferably 1.4 g/cm 3 or more, still more preferably 1.5 g/cm 3 or more, and preferably 2.0 g/cm 3 or more. 3 or less, more preferably 1.9 g/cm 3 or less, and still more preferably 1.8 g/cm 3 or less. If this range is exceeded, the permeability of the solid electrolyte to the vicinity of the interface between the current collector and the active material is reduced, and the charging/discharging characteristics especially at high current densities are deteriorated, and high output may not be obtained. On the other hand, if it falls below, the conductivity between the active materials will decrease, the battery resistance will increase, and high output may not be obtained.
• the thickness of the negative electrode is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the mixture sheet minus the thickness of the metal foil of the current collector is preferably the lower limit with respect to one side of the current collector. is 10 ⁇ m or more, more preferably 20 ⁇ m or more, and preferably 500 ⁇ m or less, more preferably 450 ⁇ m or less.
• the present disclosure is also a solid secondary battery using the mixture sheet for a secondary battery.
• the solid secondary battery may be an all-solid secondary battery or a hybrid solid secondary battery in which a gel polymer electrolyte and a solid electrolyte are combined.
• the solid secondary battery is preferably a lithium ion battery.
• a solid secondary battery of the present disclosure is a solid secondary battery comprising a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode, wherein the positive electrode, the negative electrode, and the solid electrolyte layer include the present It contains a positive electrode sheet, a negative electrode sheet, or a solid electrolyte layer sheet, which is the disclosed secondary battery mixture sheet.
• a material other than the secondary battery mixture sheet of the present disclosure may be used for part of the positive electrode, the negative electrode, and the solid electrolyte layer.
• the laminated structure of the solid secondary battery in the present disclosure includes a positive electrode including a positive electrode sheet and a positive electrode current collector, a negative electrode including a negative electrode sheet and a negative electrode current collector, and a sulfide system sandwiched between the positive electrode and the negative electrode.
• a solid electrolyte layer is provided.
• the solid secondary battery of the present disclosure may have a separator between the positive electrode and the negative electrode.
• the separator include porous membranes such as polyethylene and polypropylene; nonwoven fabrics made of resins such as polypropylene; and nonwoven fabrics such as glass fiber nonwoven fabrics.
• the solid secondary battery of the present disclosure may further include a battery case.
• the shape of the battery case used in the present disclosure is not particularly limited as long as it can accommodate the above-described positive electrode, negative electrode, electrolyte layer for a sulfide-based solid battery, etc. Specifically, it is cylindrical. , square type, coin type, laminate type, and the like.
• the positive electrode, the solid electrolyte layer sheet, and the negative electrode may be sequentially laminated and pressed to form a solid secondary battery.
• the secondary battery mixture sheet of the present disclosure it is possible to manufacture a solid secondary battery in a state where the system contains less water, and a solid secondary battery having good performance can be obtained. , is preferred.
• the polytetrafluoroethylene aqueous dispersion thus obtained was diluted to a solid content concentration of 15% and gently stirred in the presence of nitric acid in a vessel equipped with a stirrer to solidify the polytetrafluoroethylene.
• the solidified polytetrafluoroethylene was separated and dried at 160° C. for 18 hours to obtain powdery PTFE-1.
• Powdered PTFE-2 was produced with reference to Preparation Example 3 of International Publication No. 2015-080291.
• Powdered PTFE-3 was produced with reference to Preparation Example 1 of International Publication No. 2012/086710.
• Powdered PTFE-4 was produced with reference to Preparation Example 1 of WO 2012-063622. Table 1 shows the physical properties of the produced PTFE.
• Example 1 A sulfide-based solid electrolyte Li 10 SnP 2 S 12 (LSPS, 0.714Li 2 S-0.143SnS 2 -0.143P 2 S 5 ) (average particle size: 7 ⁇ m) and powdered PTFE-1 were weighed and subjected to high-speed Mixed with a mixer (500 rpm, 1 minute). Stirring was carried out while the container was cooled to 10°C. After that, the mixture was stirred with a high-speed mixer (10000 rpm, 3 minutes) to obtain a mixture. Stirring was performed by heating the container to 60°C. The solid content was such that the mass ratio of solid electrolyte:binder was 98.5:1.5.
• the powdery PTFE-1 was dried in a vacuum dryer at 50° C. for 1 hour before use.
• the powdery PTFE was sieved in advance using a stainless steel sieve with an opening of 500 ⁇ m, and the material remaining on the sieve was used.
• the resulting mixture was formed into bulk and rolled into sheets. Rolling was performed by heating to 80°C. After that, the rolled sheet obtained earlier is folded in two to be roughly crushed, and then formed into a bulk shape again, and then rolled into a sheet shape using a metal roll on a flat plate to fibrillate.
• the step of accelerating was repeated four times. After that, by further rolling, a sheet-like solid electrolyte layer having a thickness of 500 ⁇ m was obtained.
• the sheet-like solid electrolyte layer was cut out and put into a press for rolling. Furthermore, the thickness was adjusted by repeatedly applying a load of 5 kN. The gap was adjusted so that the final thickness of the solid electrolyte layer was 120 ⁇ m. The above operation was performed in an Ar glove box (dew point of about -80°C).
• Example 2 A sulfide-based solid electrolyte Li 10 SnP 2 S 12 (LSPS) and powdery PTFE-2 were weighed and formed into a sheet in the same manner as in Example 1. The composition ratio was adjusted to the mass ratio shown in Table 2.
• Example 3 A sulfide-based solid electrolyte Li 10 SnP 2 S 12 (LSPS) and powdery PTFE-3 were weighed and formed into a sheet in the same manner as in Example 1. The composition ratio was adjusted to the mass ratio shown in Table 2.
• Example 4 A sulfide-based solid electrolyte Li 10 SnP 2 S 12 (LSPS) and powdery PTFE-4 were weighed and formed into a sheet in the same manner as in Example 1. The composition ratio was adjusted to the mass ratio shown in Table 2.
• Example 5 A sulfide-based solid electrolyte Li 6 PS 5 Cl (LPSCl, 0.625Li 2 S-0.25LiCl-0.125P 2 S 5 ) (average particle size: 8 ⁇ m) and powdered PTFE-1 were weighed, and Example 1 Sheet molding was performed in the same procedure as . The composition ratio was adjusted to the mass ratio shown in Table 2.
• Example 6 A positive electrode active material LiNi 0.8 Mn 0.1 Co 0.1 O 2 , a sulfide-based solid electrolyte LPSCl (average particle size: 8 ⁇ m), and powdered PTFE-1 were weighed and formed into a sheet in the same manner as in Example 1. did The composition ratio was adjusted to the mass ratio shown in Table 3.
• Example 7 A positive electrode active material LiNi 0.8 Co 0.15 Al 0.05 O 2 , a sulfide-based solid electrolyte LPSCl (average particle size: 8 ⁇ m) and powdered PTFE-1 were weighed and sheet-formed in the same manner as in Example 1. did The composition ratio was adjusted to the mass ratio shown in Table 3.
• Example 8 A sulfide-based solid electrolyte Li 10 GeP 2 S 12 (LGPS, manufactured by Ampcera, average particle size: 18 ⁇ m) and powdery PTFE-2 were weighed and formed into a sheet in the same manner as in Example 1. The composition ratio was adjusted to the mass ratio shown in Table 3.
• the solid electrolyte sheet prepared in Example 2 was layered and uniaxially molded for 3 minutes under a load of 60 kN. By doing so, they were integrated and a punched half cell with a diameter of 10 mm was produced.
• the half cell produced was placed in a flat cell and placed in a tank at 25° C. for 12 hours. Charging and discharging were performed at 0.1C (0.05C cut). As a result of 8 cycles of charging and discharging, the capacity retention rate at the 8th cycle was 98.4% when the 3rd cycle was taken as 100%.
• the secondary battery mixture of the present disclosure and the secondary battery mixture sheet containing the same can be used for manufacturing a solid secondary battery.

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