WO2021250803A1 - ２次電池及びその製造方法 - Google Patents

２次電池及びその製造方法 Download PDF

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Publication number
WO2021250803A1
WO2021250803A1 PCT/JP2020/022791 JP2020022791W WO2021250803A1 WO 2021250803 A1 WO2021250803 A1 WO 2021250803A1 JP 2020022791 W JP2020022791 W JP 2020022791W WO 2021250803 A1 WO2021250803 A1 WO 2021250803A1
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Prior art keywords
negative electrode
secondary battery
sheet
bending
positive electrode
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Ceased
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PCT/JP2020/022791
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English (en)
French (fr)
Japanese (ja)
Inventor
健 緒方
重浩 金
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Terawatt Technology KK
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Terawatt Technology KK
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Application filed by Terawatt Technology KK filed Critical Terawatt Technology KK
Priority to KR1020227044817A priority Critical patent/KR20230014733A/ko
Priority to JP2022530418A priority patent/JP7680766B2/ja
Priority to PCT/JP2020/022791 priority patent/WO2021250803A1/ja
Priority to EP20940431.8A priority patent/EP4167333A4/en
Priority to CN202080101813.3A priority patent/CN115699397B/zh
Publication of WO2021250803A1 publication Critical patent/WO2021250803A1/ja
Priority to US18/077,025 priority patent/US20230100167A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/04—Construction or manufacture in general
    • H01M10/0431—Cells with wound or folded electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/04—Construction or manufacture in general
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/045—Cells or batteries with folded plate-like electrodes
    • H01M10/0454—Cells or batteries with electrodes of only one polarity folded
    • 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
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0583—Construction or manufacture of accumulators with folded construction elements except wound ones, i.e. folded positive or negative electrodes or separators, e.g. with "Z"-shaped electrodes or separators
    • 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
    • H01M4/0438—Processes of manufacture in general by electrochemical processing
    • H01M4/044—Activating, forming or electrochemical attack of the supporting material
    • H01M4/0445—Forming after manufacture of the electrode, e.g. first charge, cycling
    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/024—Insertable electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a secondary battery and a method for manufacturing the same.
  • a secondary battery that charges and discharges by moving metal ions between a positive electrode and a negative electrode is known to exhibit high voltage and high energy density, and is typically a lithium ion secondary battery. It has been known.
  • an active material capable of holding lithium is introduced into the positive electrode and the negative electrode, and charging / discharging is performed by exchanging lithium ions between the positive electrode active material and the negative electrode active material.
  • a lithium metal secondary battery that holds lithium by precipitating lithium metal on the surface of the negative electrode has been developed.
  • Patent Document 1 describes a high energy density, high power lithium metal anode having a volumetric energy density of greater than 1000 Wh / L and / or a mass energy density of greater than 350 Wh / kg when discharged at room temperature at a rate of at least 1 C. Secondary batteries are disclosed. Patent Document 1 discloses the use of an ultrathin lithium metal anode in order to realize such a lithium metal anode secondary battery.
  • Patent Document 2 in a lithium secondary battery including a positive electrode, a negative electrode, a separation film interposed between them, and an electrolyte, in the negative electrode, metal particles are formed on a negative electrode current collector, and the negative electrode is charged.
  • a lithium secondary battery that is moved from the positive electrode and forms a lithium metal on the negative electrode current collector in the negative electrode is disclosed.
  • Patent Document 2 provides a lithium secondary battery in which such a lithium secondary battery solves a problem caused by the reactivity of a lithium metal and a problem generated in the assembly process, and has improved performance and life. Discloses what can be done.
  • a lithium metal secondary battery that holds lithium by precipitating lithium metal on the surface of the negative electrode as described in the above patent document has a high energy density because the negative electrode does not have a negative electrode active material.
  • expensive, mass production technology for such lithium metal secondary batteries has not yet been established because the negative electrode is very thin and its handling is not easy.
  • the lithium metal secondary battery as described in the above patent document has to be produced manually, and the productivity is lowered.
  • the present invention has been made in view of the above problems, and an object of the present invention is to provide a secondary battery having high energy density and capacity, excellent cycle characteristics, and high productivity, and a method for manufacturing the same.
  • the secondary battery according to the embodiment of the present invention is a laminate formed by alternately bending a sheet having a negative electrode having no negative electrode active material and separators arranged on both sides of the negative electrode at an acute angle a plurality of times. And a plurality of positive electrodes arranged in the gaps formed between the separators facing each other by bending the sheet.
  • Such a secondary battery includes a negative electrode having no negative electrode active material, metal is deposited on the surface of the negative electrode, and the deposited metal is dissolved to perform charging and discharging. Further, the above-mentioned secondary battery has a plurality of laminated structures of a positive electrode, a negative electrode, and a separator arranged between the positive electrode and the negative electrode. As a result, the above secondary battery has high energy density and capacity. Further, the negative electrode having no negative electrode active material is very thin and difficult to handle, whereas the sheet having the negative electrode and the separators arranged on both sides of the negative electrode is thick enough to be easy to handle. It also has mechanical strength. As a result, the above-mentioned secondary battery can be automatically manufactured by using an automatic laminating device without causing breakage or twisting of the negative electrode, and is excellent in cycle characteristics and productivity.
  • the secondary battery according to the embodiment of the present invention is a laminate formed by alternately bending a sheet having a negative electrode having no negative electrode active material and a solid electrolyte arranged on both sides of the negative electrode at a sharp angle a plurality of times. It comprises a body and a plurality of positive electrodes each arranged in each gap formed between solid electrolytes facing each other by bending the sheet.
  • Such a secondary battery includes a negative electrode having no negative electrode active material, metal is deposited on the surface of the negative electrode, and the deposited metal is dissolved to perform charging and discharging. Further, the above-mentioned secondary battery has a plurality of laminated structures of a positive electrode, a negative electrode, and a solid electrolyte arranged between the positive electrode and the negative electrode. As a result, the above secondary battery has high energy density and capacity. Further, the negative electrode having no negative electrode active material is very thin and difficult to handle, whereas the sheet having the negative electrode and the solid electrolytes arranged on both sides of the negative electrode is easy to handle. Has thickness and mechanical strength. As a result, the above-mentioned secondary battery can be automatically manufactured by using an automatic laminating device without causing breakage or twisting of the negative electrode, and is excellent in cycle characteristics and productivity.
  • the secondary battery is preferably a lithium secondary battery in which lithium metal is deposited on the surface of the negative electrode and charging / discharging is performed by dissolving the deposited lithium. According to such an embodiment, the energy density is further increased.
  • the negative electrode is preferably an electrode made of at least one selected from the group consisting of Cu, Ni, Ti, Fe, and other metals that do not react with Li, alloys thereof, and stainless steel (SUS). Is. According to such an aspect, since it is not necessary to use a highly flammable lithium metal in the production, the safety and productivity are further improved. Moreover, since such a negative electrode is stable, the cycle characteristics of the secondary battery are further improved.
  • the secondary battery preferably has no lithium foil formed on the surface of the negative electrode before the initial charge. According to such an aspect, since it is not necessary to use a highly flammable lithium metal in the production, the safety and productivity are further improved.
  • the positive electrode is preferably arranged so as to be separated from the end of the bent portion of the sheet within a range of 0.01 mm or more and 5.00 mm or less.
  • the positive electrode and the negative electrode face each other in an appropriate area via the separator or the solid electrolyte, so that the energy density and the capacity are further increased.
  • the average thickness of the negative electrode is preferably 4 ⁇ m or more and 20 ⁇ m or less. According to such an embodiment, the volume occupied by the negative electrode in the secondary battery is reduced, so that the energy density of the secondary battery is further improved.
  • the secondary battery preferably has an energy density of 350 Wh / kg or more.
  • the positive electrode may have a positive electrode active material.
  • the method for manufacturing a secondary battery according to an embodiment of the present invention includes a step of preparing a sheet having a negative electrode having no negative electrode active material and separators arranged on both sides of the negative electrode, and the sheet having a plurality of sharp angles. Molding to form a molded body including a laminated body formed by alternately bending and a plurality of positive electrodes arranged in the gaps formed between separators facing each other by bending the sheet. Including the process.
  • the secondary battery obtained by the above manufacturing method has a plurality of laminated structures of a positive electrode, a negative electrode, and a separator arranged between the positive electrode and the negative electrode.
  • the secondary battery obtained by the above manufacturing method has high energy density and capacity.
  • the negative electrode having no negative electrode active material is very thin and difficult to handle, whereas the sheet having the negative electrode and the separators arranged on both sides of the negative electrode is thick enough to be easy to handle. It also has mechanical strength.
  • the above-mentioned manufacturing method can automatically manufacture the secondary battery without forming wrinkles on the negative electrode, so that the secondary battery having high cycle characteristics can be manufactured with high productivity.
  • the method for manufacturing a secondary battery according to an embodiment of the present invention includes a step of preparing a sheet having a negative electrode having no negative electrode active material and a solid electrolyte arranged on both sides of the negative electrode, and the sheet having a sharp angle a plurality of times.
  • the secondary battery obtained by the above manufacturing method has a plurality of laminated structures of a positive electrode, a negative electrode, and a solid electrolyte arranged between the positive electrode and the negative electrode.
  • the secondary battery obtained by the above manufacturing method has high energy density and capacity.
  • the negative electrode having no negative electrode active material is very thin and difficult to handle, whereas the sheet having the negative electrode and the solid electrolytes arranged on both sides of the negative electrode is easy to handle. Has thickness and mechanical strength.
  • the above-mentioned manufacturing method can automatically manufacture the secondary battery without forming wrinkles on the negative electrode, so that the secondary battery having high cycle characteristics can be manufactured with high productivity.
  • the first flat plate is pressed against the sheet from the first direction perpendicular to the laminating direction of the laminated body, and the second flat plate is pressed against the sheet from the second direction opposite to the first direction.
  • the first flat plate and the second flat plate include the positive electrode and a substrate integrated with the positive electrode, and are formed by bending the sheet at the same time as bending the sheet in the bending step.
  • the positive electrode may be inserted into each gap. According to such an embodiment, it is possible to more easily form a laminated structure of the positive electrode, the negative electrode, and the separator or the solid electrolyte arranged between the positive electrode and the negative electrode, so that the productivity is further increased.
  • the molding step may include a step of inserting the positive electrode into each gap formed by bending the sheet after the bending step.
  • the present invention it is possible to provide a secondary battery having high energy density and capacity, excellent cycle characteristics, and high productivity, and a method for manufacturing the same.
  • the present embodiments will be described in detail with reference to the drawings as necessary.
  • the same elements are designated by the same reference numerals, and duplicate description will be omitted.
  • the positional relationship such as up, down, left, and right shall be based on the positional relationship shown in the drawings unless otherwise specified.
  • the dimensional ratios in the drawings are not limited to the ratios shown.
  • FIG. 1 is a schematic cross-sectional view of a secondary battery according to the first embodiment.
  • the secondary battery 100 according to the first embodiment includes a negative electrode 120 having no negative electrode active material and a first separator 110a and a second separator 110b arranged on both sides of the negative electrode 120.
  • the laminated body 150 formed by alternately bending the sheet 130 having an acute angle a plurality of times, and a plurality of positive electrodes 140 arranged in the gaps formed between the separators facing each other due to the bending of the sheets. And.
  • the sheet 130 has a negative electrode 120 having no negative electrode active material, and a first separator 110a and a second separator 110b arranged on both sides of the negative electrode 120.
  • the negative electrode 120 does not have a negative electrode active material. It is difficult to increase the energy density of a secondary battery including a negative electrode having a negative electrode active material due to the presence of the negative electrode active material. On the other hand, since the secondary battery 100 of the present embodiment includes the negative electrode 120 having no negative electrode active material, such a problem does not occur. That is, the secondary battery 100 of the present embodiment has a high energy density because metal is deposited on the surface of the negative electrode 120 and the deposited metal is dissolved to perform charging and discharging.
  • the term "negative electrode active material” means a material for holding a metal ion that becomes a charge carrier in a battery or a metal corresponding to the metal ion (hereinafter, referred to as "carrier metal") in the negative electrode 120. However, it may be paraphrased as a host material of a carrier metal. The mechanism of such holding is not particularly limited, and examples thereof include intercalation, alloying, and occlusion of metal clusters. As used herein, the negative electrode active material is typically a material for retaining lithium metal or lithium ions in the negative electrode 120.
  • the negative electrode active material is not particularly limited, and examples thereof include carbon-based substances, metal oxides, metals, alloys, and the like.
  • the carbon-based material is not particularly limited, and examples thereof include graphene, graphite, hard carbon, mesoporous carbon, carbon nanotubes, and carbon nanohorns.
  • the metal oxide is not particularly limited, and examples thereof include titanium oxide-based compounds, tin oxide-based compounds, and cobalt oxide-based compounds.
  • the metal or alloy is not particularly limited as long as it can be alloyed with the carrier metal, and examples thereof include silicon, germanium, tin, lead, aluminum, gallium, and alloys containing these.
  • the negative electrode 120 is not particularly limited as long as it does not have a negative electrode active material and can be used as a current collector, but for example, Cu, Ni, Ti, Fe, and other metals that do not react with Li, and , These alloys, as well as those consisting of at least one selected from the group consisting of stainless steel (SUS).
  • SUS stainless steel
  • various conventionally known types of SUS can be used.
  • the negative electrode material as described above one type may be used alone or two or more types may be used in combination.
  • the “metal that does not react with Li” means a metal that does not react with lithium ions or lithium metal to alloy under the operating conditions of the secondary battery 100.
  • the negative electrode 120 is preferably a lithium-free electrode. According to such an aspect, the secondary battery 100 is further excellent in safety and productivity because it is not necessary to use a highly flammable lithium metal in the production.
  • the negative electrode 120 is more preferably selected from the group consisting of Cu, Ni, and alloys thereof, and stainless steel (SUS). It consists of one kind. From the same viewpoint, the negative electrode 120 is more preferably made of Cu, Ni, or an alloy made of these, and particularly preferably made of Cu or Ni.
  • the negative electrode does not have a negative electrode active material
  • the content of the negative electrode active material in the negative electrode is 10% by mass or less with respect to the entire negative electrode.
  • the content of the negative electrode active material in the negative electrode is preferably 5.0% by mass or less, more preferably 1.0% by mass or less, still more preferably 0.1% by mass or less, and particularly preferably 0. It is 0% by mass or less.
  • the fact that the secondary battery 100 includes a negative electrode having no negative electrode active material means that the secondary battery 100 is an anode-free secondary battery, a zero anode secondary battery, or an anodeless 2 in the sense that it is generally used. It means that it is the next battery.
  • the negative electrode 120 preferably has an adhesive layer formed on the surface thereof to enhance the adhesiveness between the deposited carrier metal and the negative electrode. According to such an aspect, when the carrier metal, particularly the lithium metal is deposited on the negative electrode 120, the adhesiveness between the negative electrode 120 and the precipitated metal can be further improved. As a result, the peeling of the precipitated metal from the negative electrode 120 can be further suppressed, so that the cycle characteristics of the secondary battery 100 are further improved.
  • Examples of the adhesive layer include metals other than the negative electrode, alloys thereof, and carbon-based substances.
  • examples of adhesive layers include Au, Ag, Pt, Sb, Pb, In, Sn, Zn, Bi, Al, Sb, Pb, Ni, Cu, graphene, graphite, etc.
  • examples thereof include hard carbon, meso-graphite carbon, carbon nanotubes, and carbon nanohorns.
  • the thickness of the adhesive layer is not particularly limited, but is preferably 1 nm or more and 300 nm or less, and more preferably 50 nm or more and 150 nm or less.
  • the adhesive layer corresponds to the above-mentioned negative electrode active material
  • the adhesive layer is 10% by mass or less, preferably 5.0% by mass or less, and more preferably 1.0% by mass or less with respect to the negative electrode. More preferably, it is 0.1% by mass or less.
  • the average thickness of the negative electrode 120 is preferably 4 ⁇ m or more and 20 ⁇ m or less, more preferably 5 ⁇ m or more and 18 ⁇ m or less, and further preferably 6 ⁇ m or more and 15 ⁇ m or less. According to such an embodiment, the volume occupied by the negative electrode 120 in the secondary battery 100 is reduced, so that the energy density of the secondary battery 100 is further improved.
  • the first separator 110a is for separating the positive electrode 140 and the negative electrode 120 to prevent the battery from short-circuiting, and to secure the ionic conductivity of the metal ion serving as a charge carrier between the positive electrode 140 and the negative electrode 120. It is made of a material that does not have conductivity and does not react with metal ions. Further, when an electrolytic solution is used, the first separator 110a also plays a role of holding the electrolytic solution.
  • the first separator 110a is not limited as long as it plays the above role, but is composed of, for example, porous polyethylene (PE), polypropylene (PP), or a laminated structure thereof.
  • the first separator 110a may be covered with a separator coating layer.
  • the separator coating layer may cover both sides of the first separator 110a, or may cover only one side.
  • the separator coating layer is not particularly limited as long as it is a member having ionic conductivity and does not react with metal ions serving as charge carriers, but the first separator 110a and the layer adjacent to the first separator 110a are firmly bonded to each other. It is preferable that it can be adhered.
  • the separator coating layer is not particularly limited, and is, for example, polyvinylidene fluoride (PVDF), a mixture of styrene-butadiene rubber and carboxymethyl cellulose (SBR-CMC), polyacrylic acid (PAA), and lithium polyacrylate.
  • Examples include those containing binders such as (Li-PAA), polyimide (PI), polyamideimide (PAI), and aramid.
  • binders such as (Li-PAA), polyimide (PI), polyamideimide (PAI), and aramid.
  • inorganic particles such as silica, alumina, titania, zirconia, magnesium oxide, and magnesium hydroxide may be added to the binder.
  • the average thickness of the first separator 110a is preferably 30 ⁇ m or less, more preferably 25 ⁇ m or less, and further preferably 20 ⁇ m or less. According to such an embodiment, the volume occupied by the first separator 110a in the secondary battery 100 is reduced, so that the energy density of the secondary battery 100 is further improved.
  • the average thickness of the first separator 110a is preferably 3 ⁇ m or more, more preferably 5 ⁇ m or more. According to such an aspect, the positive electrode 140 and the negative electrode 120 can be more reliably isolated, and the short circuit of the battery can be further suppressed.
  • the second separator 110b may be the same as or different from the first separator 110a as long as it has the above-mentioned configuration as the configuration of the first separator 110a.
  • a preferred embodiment of the second separator 110b is the same as that of the first separator 110a.
  • the laminated body 150 is formed by bending the sheet 130 at an acute angle at a plurality of bent portions 160, and the bent portions 160 and the flat surface portions 170 are alternately connected in the stacking direction Z. It has a zigzag structure (also referred to as a "spin-fold structure").
  • bending at an acute angle at the bent portion 160 means that the angle formed by the two flat portions 170 connected to the bent portion 160 is an acute angle.
  • the laminated body 150 preferably has a bent portion 160 such that the angle formed by the two flat portions 170 connected to the bent portion 160 is about 0 degrees in the bent portion 160. That is, the laminated body 150 is preferably bent so that the adjacent flat surface portions 170 are substantially parallel to each other. According to such an aspect, the number of layers in the laminate 150 can be further increased.
  • the number of laminated bodies 150 means the number of times the sheet 130 is bent, and corresponds to the number of bent portions 160.
  • the laminated body 150 formed by bending the sheet 130 three times has four flat surface portions 170 and three bent portions 160, and the number of laminated layers is three.
  • the angle formed by the two flat portions 170 connected to the bent portion 160 may be 0 degrees or more, 1 degree or more, or 3 degrees or more. It may be 5 degrees or more, 10 degrees or more, or 15 degrees or more. In the bent portion 160 of the laminated body 150, the angle formed by the two flat portions 170 connected to the bent portion 160 may be 40 degrees or less, 30 degrees or less, or 20 degrees or less. It may be 18 degrees or less.
  • the secondary battery 100 includes a laminated body having two or more laminated bodies, that is, three flat surface portions 170 and two bent portions 160.
  • the number of stacked secondary batteries 100 is preferably 3 or more, more preferably 5 or more, and further preferably 10 or more. When the number of stacked secondary batteries 100 is within the above range, the capacity of the secondary battery 100 is further improved.
  • the upper limit of the number of layers of the secondary battery 100 is not particularly limited, but the number of layers may be 50 or less, 40 or less, or 30 or less. When the number of stacked secondary batteries 100 is within the above range, the productivity is further improved.
  • FIG. 2 is a schematic cross-sectional view of a conventional secondary battery.
  • the conventional secondary battery 200 has a structure in which a plurality of positive electrodes 210, a separator 220, and a negative electrode 230 having a negative electrode active material are laminated.
  • the conventional secondary battery 200 can be automatically laminated by the automatic laminating device as follows, the energy density is low due to the presence of the negative electrode active material of the negative electrode 230.
  • the process for automatically laminating the conventional secondary battery 200 by the automatic laminating device is as follows. First, a plurality of positive electrodes 210, separator 220, and negative electrode 230 are prepared and set at predetermined positions of the automatic laminating device for each type. Next, the automatic laminating device takes out one of the positive electrodes 210 set at a predetermined position. Similarly, the automatic laminating device takes out the separator 220 and the negative electrode 230 set at predetermined positions one by one, and stacks them in the above order to form a structure in which the positive electrode 210, the separator 220, and the negative electrode 230 are laminated. obtain. By repeating the above laminating procedure, a structure in which a plurality of the positive electrode 210, the separator 220, and the negative electrode 230 shown in FIG. 2 are laminated can be obtained.
  • the secondary battery is manufactured by using the negative electrode having no negative electrode active material instead of the negative electrode 230 having the negative electrode active material, the positive electrode, the separator, and the separator are manufactured by the same automatic lamination as the above method.
  • the negative electrode having no negative electrode active material is very thin and difficult to handle, so that the laminated negative electrode tends to be wrinkled.
  • the carrier metal deposited on the negative electrode has insufficient adhesion to the negative electrode, and the carrier metal deposited on the negative electrode is removed from the negative electrode when the secondary battery is used. It becomes easy to peel off. As a result, such secondary batteries are inferior in cycle characteristics.
  • the negative electrode 120 which is very thin and difficult to handle, is not laminated alone, but is arranged on both sides of the negative electrode 120 and the negative electrode 120.
  • a laminated body 150 in which a sheet 130 in which a separator 110a of 1 and a separator 110b of a second are integrated is laminated is provided. Since the sheet 130 includes the negative electrode 120, the first separator 110a, and the second separator 110b, the average thickness thereof is thicker than the average thickness of the negative electrode 120, and the sheet 130 is easy to handle. Further, since the negative electrode 120 is sandwiched between the first separator 110a and the second separator 110b and physical pressure is applied from both sides, wrinkles are less likely to occur. As a result, the secondary battery 100 can be formed by the automatic laminating device while suppressing the occurrence of wrinkles on the negative electrode 120, so that the secondary battery 100 has excellent cycle characteristics and high productivity.
  • the positive electrode 140 is arranged in each gap formed by bending the sheet 130. More specifically, the positive electrodes 140 are arranged between the flat surface portions 170 adjacent to each other.
  • the positive electrode 140 arranged between a certain flat surface portion 170 (first flat surface portion 170) and the flat surface portion 170 (second flat surface portion 170) adjacent to the stacking direction Z of the first flat surface portion 170 is One surface faces the first separator 110a belonging to the first flat surface portion 170, and the other surface faces the first separator 110a belonging to the second flat surface portion 170.
  • the positive electrode 140 arranged between the first flat surface portion 170 and the flat surface portion 170 (third flat surface portion 170) adjacent to the first flat surface portion 170 in the direction opposite to the stacking direction Z has one side thereof.
  • the other surface faces the second separator 110b belonging to the flat surface portion 170 of 1, and the other surface faces the second separator 110b belonging to the third flat surface portion 170.
  • the positive electrode 140 Since the positive electrode 140 is arranged between the flat surface portions 170 adjacent to each other as described above, the positive electrode 140 faces the negative electrode 120 on both sides of the positive electrode 140 via the first separator 110a or the second separator 110b. .. Further, the secondary battery 100 can include a plurality of positive electrodes 140. As a result, the capacity of the secondary battery 100 is improved.
  • the positive electrode 140 is arranged so as to be separated from the end portion (bent end portion) 180 of the bent portion 160 in the laminated body 150, preferably in a range of 0.01 mm or more and 5.00 mm or less. That is, the distance d between the positive electrode 140 and the bent end portion 180 is preferably 0.01 mm or more and 5.00 mm or less. When the distance d is 0.01 mm or more, the time required for positioning the positive electrode 140 is shortened, so that the productivity of the secondary battery 100 is further improved. Further, when the distance d is 5.00 mm or less, the facing area between the positive electrode 140 and the negative electrode 120 is further increased, so that the energy density and capacity of the secondary battery 100 are further improved. From the same viewpoint, the distance d is more preferably 0.05 mm or more and 4.00 mm or less, and further preferably 0.10 mm or more and 3.00 mm or less.
  • the distance d between the positive electrode 140 and the bent end 180 may be measured as follows. First, the secondary battery 100 is cut in a plane parallel to the stacking direction Z and perpendicular to at least one bent portion 160. The obtained cut surface is observed visually, using a method such as an optical microscope or an electron microscope, and the distance d between the positive electrode 140 and the bent end portion 180 is measured for at least two or more positive electrodes 140. By obtaining the arithmetic mean of the measurement results, the distance d between the positive electrode 140 and the bent end portion 180 can be obtained.
  • the bent end portion 180 is the point where the distance from the positive electrode 140 of the bent portions 160 is the longest on the cut surface of the secondary battery 100. In other words, if the distance between the positive electrode 140 and an arbitrary point on the bent portion 160 on the cut surface of the secondary battery 100 is d', the point on the bent portion 160 where d'is maximized is the bent end. Part 180.
  • the positive electrode 140 is not particularly limited as long as it is generally used for a secondary battery, but a known material can be appropriately selected depending on the use of the secondary battery and the type of carrier metal. From the viewpoint of increasing the stability and output voltage of the secondary battery, the positive electrode 140 preferably has a positive electrode active material.
  • the "positive electrode active material” means a substance for holding the carrier metal on the positive electrode 140, and may be paraphrased as a host material of the carrier metal. As used herein, the positive electrode active material is typically a substance for retaining lithium ions in the positive electrode 140.
  • Such positive electrode active material is not particularly limited, and examples thereof include metal oxides and metal phosphates.
  • the metal oxide is not particularly limited, and examples thereof include a cobalt oxide-based compound, a manganese oxide-based compound, and a nickel oxide-based compound.
  • the metal phosphate is not particularly limited, and examples thereof include iron phosphate compounds and cobalt phosphate compounds.
  • the metal carrier is a lithium ion
  • examples thereof include O 4 , LiFePO, LiCoPO, LiFeOF, LiNiOF, and TiS 2 .
  • the positive electrode active material as described above one type may be used alone or two or more types may be used in combination.
  • the positive electrode 140 may contain components other than the above-mentioned positive electrode active material. Such components include, but are not limited to, known conductive aids, binders, solid polymer electrolytes, and inorganic solid electrolytes.
  • the conductive auxiliary agent in the positive electrode 140 is not particularly limited, and examples thereof include carbon black, single-walled carbon nanotubes (SW-CNT), multi-walled carbon nanotubes (MW-CNT), carbon nanofibers, and acetylene black. ..
  • the binder is not particularly limited, and examples thereof include polyvinylidene fluoride, polytetrafluoroethylene, styrene-butadiene rubber, acrylic resin, and polyimide resin.
  • the content of the positive electrode active material in the positive electrode 140 may be, for example, 50% by mass or more and 100% by mass or less with respect to the entire positive electrode 140.
  • the content of the conductive auxiliary agent may be, for example, 0.5% by mass and 30% by mass or less with respect to the entire positive electrode 140.
  • the content of the binder may be, for example, 0.5% by mass and 30% by mass or less with respect to the entire positive electrode 140.
  • the total content of the solid polymer electrolyte and the inorganic solid electrolyte may be, for example, 0.5% by mass and 30% by mass or less with respect to the entire positive electrode 140.
  • the secondary battery 100 may have an electrolytic solution.
  • the electrolytic solution may be infiltrated into the first separator 110a and / or the second separator 110b, or the secondary battery 100 may be the one in which the electrolytic solution is sealed together with the laminated body 150.
  • the electrolytic solution is a solution containing an electrolyte and a solvent and having ionic conductivity, and acts as a conductive path for lithium ions. Therefore, in the secondary battery 100 having the electrolytic solution, the internal resistance is further lowered, and the energy density, the capacity, and the cycle characteristics are further improved.
  • the electrolyte is not particularly limited as long as it is a salt, and examples thereof include salts of Li, Na, K, Ca, and Mg.
  • a lithium salt is preferably used as the electrolyte.
  • the lithium salt is not particularly limited, but LiI, LiCl, LiBr, LiF, LiBF 4 , LiPF 6 , LiAsF 6 , LiSO 3 CF 3 , LiN (SO 2 F) 2 , LiN (SO 2 CF 3 ) 2 , LiN.
  • LiN (SO 2 F) 2 is preferable as the lithium salt from the viewpoint of further improving the energy density, capacity, and cycle characteristics of the secondary battery 100.
  • the above lithium salts may be used alone or in combination of two or more.
  • the solvent is not particularly limited, but is not particularly limited, for example, dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, acetonitrile, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, chloroethylene carbonate, fluoroethylene carbonate, difluoroethylene.
  • the above-mentioned solvents may be used alone or in combination of two or more.
  • FIG. 3 is a schematic perspective view of the secondary battery according to the first embodiment.
  • the secondary battery 100 according to the first embodiment includes at least one negative electrode terminal 310 on the flat surface portion 170 of the laminated body 150. Further, the secondary battery 100 includes a positive electrode terminal 320 on each positive electrode.
  • the negative electrode terminal 310 and the positive electrode terminal 320 are each connected to an external circuit.
  • the material of the negative electrode terminal 310 and the positive electrode terminal 320 is not particularly limited as long as it is conductive, and examples thereof include Al and Ni.
  • the secondary battery 100 is charged and discharged by connecting the negative electrode terminal 310 to one end of the external circuit and the positive electrode terminal 320 to the other end of the external circuit.
  • the negative electrode terminal 310 When a plurality of negative electrode terminals 310 are present, all the negative electrode terminals 310 are connected to an external circuit so as to have the same potential.
  • the positive electrode terminals 320 are also connected to the external circuit so that all the positive electrode terminals 320 have the same potential.
  • the secondary battery 100 is charged by applying a voltage between the positive electrode terminal 320 and the negative electrode terminal 310 so that a current flows from the negative electrode terminal 310 to the positive electrode terminal 320 through an external circuit.
  • precipitation of carrier metal occurs at the interface between the negative electrode 120 and the first separator 110a and at the interface between the negative electrode 120 and the second separator 110b.
  • the deposited carrier metal is typically a lithium metal. Since the negative electrode 120 in the secondary battery 100 is suppressed from wrinkling, the precipitated carrier metal has excellent adhesiveness to the negative electrode 120. As a result, the carrier metal deposited on the negative electrode 120 does not easily peel off from the negative electrode, and the secondary battery 100 has excellent cycle characteristics.
  • a solid electrolyte interface layer (SEI layer) is formed at the interface between the negative electrode 120 and the first separator 110a and / or the interface between the negative electrode 120 and the second separator 110b by the initial charge. May be good.
  • the SEI layer formed is not particularly limited, but may contain, for example, an inorganic substance of the carrier metal and an organic substance of the carrier metal. Typically, an inorganic compound containing lithium, an organic compound containing lithium, and the like may be contained.
  • the typical average thickness of the SEI layer is 1 nm or more and 10 ⁇ m or less.
  • the carrier metal deposited during charging of the secondary battery 100 may be deposited at the interface between the negative electrode 120 and the SEI layer, and the SEI layer and the first separator 110a may be deposited. It may be deposited at the interface with the SEI layer, or it may be deposited at the interface between the SEI layer and the second separator 110b.
  • the secondary battery 100 After charging, when the positive electrode terminal 320 and the negative electrode terminal 310 are connected, the secondary battery 100 is discharged.
  • the precipitation of the carrier metal generated at at least one of the interface between the negative electrode 120 and the SEI layer, the interface between the SEI layer and the first separator 110a, and the interface between the SEI layer and the second separator 110b is dissolved.
  • the method for manufacturing the secondary battery of the present embodiment is formed by preparing a sheet having a negative electrode having no negative electrode active material and separators arranged on both sides of the negative electrode, and the sheet being alternately bent at a sharp angle a plurality of times.
  • the present invention includes a molding step of molding a molded body including the laminated body to be formed and a plurality of positive electrodes respectively arranged in the gaps formed between separators facing each other by bending the sheet.
  • FIG. 4 shows a flowchart of a method for manufacturing the secondary battery 100 according to the first embodiment shown in FIG. Each step will be described below.
  • sheet preparation process In the method for manufacturing a secondary battery of the present embodiment, first, a sheet having a negative electrode having no negative electrode active material and separators arranged on both sides of the negative electrode is prepared (sheet preparation step, step 1).
  • the sheet preparation step is a method that does not cause wrinkles on the negative electrode, and is not particularly limited as long as it is a step of arranging separators on both sides of the negative electrode, and for example, a roll-to-roll method can be used. ..
  • the roll-to-roll method may be, for example, as follows. That is, a roll containing a sheet containing the material constituting the negative electrode 120 (hereinafter referred to as “negative electrode sheet”) and a sheet containing the material constituting the first separator 110a (hereinafter referred to as “first separator sheet””. A roll containing the material constituting the second separator 110b (hereinafter referred to as "second separator sheet”) is prepared. These rolls are placed in a predetermined device, and the negative electrode sheet is sandwiched between the first separator sheet and the second separator sheet while returning each roll to a sheet shape, and the negative electrode sheet is pressed in the thickness direction of the sheet. A sheet in which the first separator sheet and the second separator sheet are arranged is formed on both sides. The obtained sheet can be wound into a roll and used for the next step.
  • the roll-to-roll method When the roll-to-roll method is used in the sheet preparation step, it is possible to form a sheet in which the first separator sheet and the second separator sheet are arranged on both sides of the negative electrode sheet while pulling the negative electrode sheet in the plane direction. Wrinkles are less likely to occur on the sheet. Further, since the obtained sheet is wound into a roll, it can be easily used in a subsequent process, and the productivity is further improved.
  • the negative electrode sheet may have the same thickness as the negative electrode 120, or may be thicker than the negative electrode 120. When the negative electrode sheet is thicker than the negative electrode 120, the negative electrode sheet may be thinned by rolling the negative electrode sheet before the step of sandwiching the negative electrode sheet between the first separator sheet and the second separator sheet.
  • the sheet preparation step may include a cleaning step and a drying step before and / or after forming a sheet having a negative electrode and separators arranged on both sides of the negative electrode.
  • the cleaning step include a step of cleaning the negative electrode sheet with a solvent containing sulfamic acid and then ultrasonically cleaning with ethanol.
  • the positive electrode 140 is prepared as shown in FIG. 4 (positive electrode preparation step, step 2).
  • the method for producing the positive electrode 140 is not particularly limited as long as it is a method for obtaining the positive electrode 140 described above, and for example, a positive electrode mixture obtained by mixing a positive electrode active material, a known conductive auxiliary agent, and a known binder can be used. For example, it may be obtained by applying it to one side of a metal foil (for example, Al foil) having a diameter of 5 ⁇ m or more and 1 mm or less and press-molding it. Alternatively, a commercially available positive electrode for a secondary battery may be used.
  • the molding step in order to mold a molded body including a laminated body formed by using a sheet having an appropriate thickness and mechanical strength and a positive electrode arranged in each gap of the laminated body, the molding thereof is performed. Even if an automatic laminating device is used, the negative electrode is less likely to wrinkle. That is, it is possible to automatically mold the molded product without causing wrinkles on the negative electrode. Therefore, the method for manufacturing a secondary battery of the present embodiment can manufacture a secondary battery having excellent cycle characteristics with high productivity.
  • FIG. 5 shows one aspect of the molding process.
  • the first flat plate 500 is pressed against the sheet 130 from the first direction X1 perpendicular to the stacking direction Z of the laminated body, and from the second direction X2 opposite to the first direction.
  • the sheet 130 is bent by pressing the second flat plate 510 against the sheet 130 and pressing the sheet 130 from the direction opposite to the stacking direction Z of the laminated body.
  • the first flat plate 500 includes the positive electrode 140 and the first substrate 520 integrated with the positive electrode 140
  • the second flat plate 510 includes the positive electrode 140 and the second substrate 530 integrated with the positive electrode 140. including.
  • the first substrate 520 and the second substrate 530 are removed.
  • the formation of the laminated body 150 in FIG. 1 and the insertion of the positive electrode 140 can be performed at the same time, so that the productivity is further improved.
  • the sheet 130 When bending the sheet 130 as described above, it is preferable to apply tension in the long axis direction of the sheet 130 by fixing one end of the sheet 130 in the long axis direction and pulling the other end. According to such an aspect, since the sheet 130 can be prevented from sagging, it is possible to further suppress the occurrence of wrinkles on the negative electrode 120.
  • the tension applied in the major axis direction of the sheet 130 can be appropriately adjusted depending on the thickness of the sheet 130 and the like, but may be, for example, 0.1 kgf or more and 10.0 kgf or less.
  • the method of integrating the positive electrode 140 and the first substrate 520 is not particularly limited, but for example, a method of placing the positive electrode 140 on the first substrate 520 may be used for suction.
  • a method of adsorbing the positive electrode 140 using the first substrate 520 connected to the apparatus may be used.
  • the method of adsorbing the positive electrode 140 using the first substrate 520 connected to the suction device it is necessary to release the adsorption of the positive electrode 140 before removing the first substrate 520.
  • the molding step is formed by bending the sheet 130 of FIG. 1 to form the laminate 150 of FIG. 1 and bending the sheet 130 of FIG. It may include an insertion step of inserting the positive electrode 140 of FIG. 1 into each of the gaps.
  • the first flat plate is pressed against the sheet 130 from the first direction perpendicular to the laminating direction of the laminated body, and the second flat plate is pressed against the sheet 130 from the second direction opposite to the first direction.
  • This is a step of bending the sheet 130 by hitting the sheet 130 and pressing the sheet 130 from the direction opposite to the stacking direction of the laminated body, and then removing the first flat plate and the second flat plate.
  • the laminated body 150 shown in FIG. 1 is obtained.
  • the insertion step is a step of inserting the positive electrode 140 into each gap of the laminate 150 of FIG. 1 obtained in the bending step. That is, in the insertion step, the positive electrode 140 is inserted between the flat surface portions 170 adjacent to each other.
  • a molded body in which a plurality of positive electrodes 140 are arranged in the respective gaps of the laminated body 150 is sealed in a closed container to obtain an inclusion body, which is used as a secondary battery 100.
  • the electrolytic solution may be encapsulated in a closed container.
  • the closed container in the encapsulation process is not particularly limited, and examples thereof include a laminated film.
  • FIG. 7 is a schematic perspective view of the secondary battery according to the second embodiment.
  • the secondary battery 700 according to the second embodiment includes a negative electrode terminal 310 on each flat surface portion 170 of the laminated body 150. Further, the secondary battery 700 is provided with a positive electrode terminal 320 on each positive electrode.
  • the plurality of negative electrode terminals 310 are connected to an external circuit so that all the negative electrode terminals 310 have the same potential.
  • the negative electrode 120 since the negative electrode 120 has a plurality of negative electrode terminals 310 and the negative electrode terminals 310 are connected so as to have the same potential, the negative electrode 120 is more easily maintained at the same potential and is secondary.
  • the internal resistance of the battery 700 is further reduced. As a result, the energy density, capacity, and cycle characteristics of the secondary battery 700 are further improved.
  • the secondary battery 700 has the same configuration as the secondary battery 100 according to the first embodiment except for the above, and has the same effect.
  • FIG. 8 is a schematic cross-sectional view of the secondary battery according to the third embodiment.
  • the first solid electrolyte 810a and the second solid electrolyte arranged on both sides of the negative electrode 120 and the negative electrode 120 having no negative electrode active material are provided.
  • a positive electrode 140 is provided.
  • the secondary battery 800 has the first separator 110a and the second separator 110b as the first solid electrolyte 810a and the second solid electrolyte 810b, respectively. It is a modified one.
  • Solid electrolyte In general, a battery provided with a liquid electrolyte tends to have a different physical pressure from the electrolyte to the surface of the negative electrode depending on the location due to the fluctuation of the liquid.
  • the secondary battery 800 since the secondary battery 800 includes the first solid electrolyte 810a and the second solid electrolyte 810b, the pressure applied to the surface of the negative electrode 120 from the first solid electrolyte 810a and the second solid electrolyte 810b is more uniform. Therefore, the shape of the carrier metal deposited on the surface of the negative electrode 120 can be further made uniform. That is, according to such an embodiment, the carrier metal deposited on the surface of the negative electrode 120 is further suppressed from growing in a dendrite shape, so that the cycle characteristics of the secondary battery 800 are further improved.
  • the first solid electrolyte 810a is not particularly limited as long as it is generally used for a solid battery, but a known material can be appropriately selected depending on the use of the secondary battery 800 and the type of carrier metal. ..
  • the first solid electrolyte 810a preferably has ionic conductivity and no electron conductivity. Since the first solid electrolyte 810a has ionic conductivity and no electron conductivity, the internal resistance of the secondary battery 800 is further reduced, and the short circuit inside the secondary battery 800 is further prevented. It can be suppressed. As a result, the energy density, capacity, and cycle characteristics of the secondary battery 800 are further improved.
  • the first solid electrolyte 810a is not particularly limited, and examples thereof include those containing a resin and a salt.
  • a resin is not particularly limited, but for example, a resin having an ethylene oxide unit in the main chain and / or the side chain, an acrylic resin, a vinyl resin, an ester resin, a nylon resin, a polysiloxane, a polyphosphazene, and a polyvinylidenefro.
  • Examples thereof include ride, polymethylmethacrylate, polyamide, polyimide, aramid, polylactic acid, polyethylene, polystyrene, polyurethane, polypropylene, polybutylene, polyacetal, polysulfone, polytetrafluoroethylene and the like.
  • the above resins may be used alone or in combination of two or more.
  • the salt contained in the first solid electrolyte 810a is not particularly limited, and examples thereof include salts of Li, Na, K, Ca, and Mg.
  • the lithium salt is not particularly limited, but LiI, LiCl, LiBr, LiF, LiBF 4 , LiPF 6 , LiAsF 6 , LiSO 3 CF 3 , LiN (SO 2 F) 2 , LiN (SO 2 CF 3 ) 2 , LiN. (SO 2 CF 3 CF 3 ) 2 , LiB (O 2 C 2 H 4 ) 2 , LiB (O 2 C 2 H 4 ) F 2 , LiB (OCOCF 3 ) 4 , LiNO 3 , and Li 2 SO 4 etc. Can be mentioned.
  • As the above-mentioned lithium salts one kind is used alone or two or more kinds are used in combination.
  • the content ratio of the resin and the lithium salt in the solid electrolyte is determined by the ratio of the oxygen atom of the resin to the lithium atom of the lithium salt ([Li] / [O]).
  • the content ratio of the resin to the lithium salt is such that the above ratio ([Li] / [O]) is preferably 0.02 or more and 0.20 or less, more preferably 0.03 or more. It is adjusted to be 0.15 or less, more preferably 0.04 or more and 0.12 or less.
  • the solvent is not particularly limited, and examples thereof include those exemplified in the electrolytic solution that can be contained in the secondary battery 100.
  • the average thickness of the first solid electrolyte 810a is preferably 20 ⁇ m or less, more preferably 18 ⁇ m or less, and further preferably 15 ⁇ m or less. According to such an embodiment, the volume occupied by the first solid electrolyte 810a in the secondary battery 800 is reduced, so that the energy density of the secondary battery 800 is further improved.
  • the average thickness of the first solid electrolyte 810a is preferably 5 ⁇ m or more, more preferably 7 ⁇ m or more, and further preferably 10 ⁇ m or more. According to such an aspect, the positive electrode 140 and the negative electrode 120 can be more reliably isolated, and the short circuit of the battery can be further suppressed.
  • the second solid electrolyte 810b may be the same as or different from the first solid electrolyte 810a as long as it has the above-mentioned configuration as the configuration of the first solid electrolyte 810a.
  • a preferred embodiment of the second solid electrolyte 810b is the same as that of the first solid electrolyte 810a.
  • solid electrolyte includes a gel electrolyte.
  • the gel electrolyte is not particularly limited, and examples thereof include those containing a polymer, an organic solvent, and a lithium salt.
  • the polymer in the gel electrolyte is not particularly limited, and examples thereof include a copolymer of polyethylene and / or polyethylene oxide, polyvinylidene fluoride, and a copolymer of polyvinylidene fluoride and hexafluoropropylene.
  • the secondary battery 800 can be manufactured in the same manner as the manufacturing method of the secondary battery 100 according to the first embodiment described above, except that a solid electrolyte is used instead of the separator.
  • the method for producing the first solid electrolyte 810a and the second solid electrolyte 810b is not particularly limited as long as it is a method for obtaining the above-mentioned solid electrolyte 810a, but for example, it may be as follows.
  • a resin conventionally used for a solid electrolyte and a salt (for example, the above-mentioned resin and salt as a resin that can be contained in the solid electrolyte 810a) are dissolved in an organic solvent.
  • a first solid electrolyte 810a and a second solid electrolyte 810b are obtained.
  • the compounding ratio of the resin and the lithium salt may be determined by the ratio ([Li] / [O]) of the oxygen atom of the resin and the lithium atom of the lithium salt, as described above.
  • the above ratio ([Li] / [O]) is, for example, 0.02 or more and 0.20 or less.
  • the organic solvent is not particularly limited, but acetonitrile may be used, for example.
  • the molding substrate is not particularly limited, but for example, a PET film or a glass substrate may be used.
  • the present embodiment is an example for explaining the present invention, and the present invention is not limited to the present embodiment.
  • the present invention can be modified in various ways as long as it does not deviate from the gist thereof. ..
  • the secondary battery of this embodiment may be a solid secondary battery.
  • the secondary battery of the present embodiment may be a lithium secondary battery in which lithium metal is deposited on the surface of the negative electrode and charging / discharging is performed by dissolving the deposited lithium.
  • the secondary battery of the present embodiment is preferably charged and discharged by depositing lithium metal on the surface of the negative electrode and dissolving the precipitated lithium. It is a lithium secondary battery to be performed.
  • the lithium foil may not be formed between the separator or the solid electrolyte and the negative electrode before the initial charging.
  • a lithium foil is not formed between the separator or the solid electrolyte and the negative electrode before the initial charging, it is not necessary to use a highly flammable lithium metal during production. Therefore, the secondary battery has higher safety and productivity.
  • the secondary battery of the present embodiment may have a current collector arranged so as to be in contact with the negative electrode or the positive electrode.
  • a current collector is not particularly limited, and examples thereof include a current collector that can be used as a negative electrode material.
  • the negative electrode and the positive electrode themselves act as current collectors.
  • high energy density or “high energy density” means that the total volume of the battery or the capacity per total mass is high, but preferably 800 Wh / L or more or 350 Wh. It is / kg or more, more preferably 900 Wh / L or more or 400 Wh / kg or more, and further preferably 1000 Wh / L or more or 450 Wh / kg or more.
  • excellent in cycle characteristics means that the rate of decrease in battery capacity is low before and after the number of charge / discharge cycles that can be expected in normal use. That is, when the initial capacity is compared with the capacity after the charge / discharge cycle of the number of times that can be expected in normal use, it means that the capacity after the charge / discharge cycle is hardly reduced with respect to the initial capacity. ..
  • the "number of times that can be assumed in normal use” is, for example, 50 times, 100 times, 500 times, 1000 times, 5000 times, or 10000 times, depending on the application in which the secondary battery is used. ..
  • the capacity after the charge / discharge cycle is hardly reduced with respect to the initial capacity depends on the application in which the secondary battery is used, but for example, the capacity after the charge / discharge cycle becomes the initial capacity. On the other hand, it means that it is 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, or 90% or more.
  • Example 1 As a negative electrode sheet, a sheet coated with 100 nm Sn foil on both sides of an 8 ⁇ m-thick Cu substrate was prepared. The negative electrode terminal was attached to the negative electrode sheet by joining the Ni terminal in advance by ultrasonic welding. As the first and second separator sheet, polyvinylidene fluoride (PVDF) and Al 2 separator surface with a mixture has been coated in O 3 (thickness: 15 [mu] m) was prepared. The negative electrode sheet was sandwiched between the first and second separator sheets and pressed in the thickness direction of the sheet to obtain a sheet in which the separators were arranged on both sides of the negative electrode.
  • PVDF polyvinylidene fluoride
  • Al 2 separator surface with a mixture has been coated in O 3
  • N-methyl-pyrrolidone (NMP) as a solvent, LiNi 0.8 Co 0.15 Al 0.05 O 2 as a positive electrode active material by 96 parts by mass, carbon black as a conductive auxiliary agent by 2 parts by mass, and a binder.
  • a mixture of 2 parts by mass of polyvinylidene fluoride (PVDF) was applied to both sides of a 12 ⁇ m Al foil and press-molded. The obtained molded body was punched to a predetermined size by punching to obtain a positive electrode.
  • the positive electrode terminal was attached to the Al foil in advance by joining the Al terminal by ultrasonic welding.
  • the obtained positive electrode is charged with a current equivalent to 0.1 C to 4.2 V (vs. Lithium metal counter electrode), and then discharged to 3.0 V (vs. Lithium metal counter electrode). It was determined that the discharge capacity of the positive electrode was 4.8 mAh / cm 2.
  • a sheet in which separators were arranged on both sides of the negative electrode was installed in an automatic laminating device, and the sheet was automatically bent at an acute angle a plurality of times to form a laminated body.
  • the automatic laminating device presses the first flat plate against the sheet from the first direction perpendicular to the laminating direction of the laminated body, and presses the first flat plate against the sheet from the second direction opposite to the first direction.
  • the sheet is bent, and then the steps of removing the first flat plate and the second flat plate are repeated.
  • the above sheet was automatically bent at an acute angle a plurality of times. In this step, bending was performed while applying tension in the long axis direction of the sheet. Further, the number of laminated bodies was adjusted so that the initial capacity of the obtained secondary battery was 10 Ah.
  • the positive electrodes prepared above were inserted into the gaps of the laminate obtained as described above. At this time, the positive electrode was inserted so that the distance between the positive electrode and the bent end portion of the laminated body was 0.01 mm or more and 5.00 mm or less. As described above, a structure in which the positive electrode 140 is arranged in each gap of the laminated body 150 as shown in FIG. 1 was obtained. Then, this was inserted into the outer body of the laminate.
  • DME dimethoxyethane
  • LFSI 4M LiN (SO 2 F) 2
  • Example 1 the above positive electrodes, separators, and negative electrodes were manually laminated one by one in this order.
  • the obtained laminate was inserted into the exterior of the laminate, and then a secondary battery was obtained in the same manner as in Example 1.
  • the number of laminated bodies was adjusted so that the initial capacity of the obtained secondary battery was 10 Ah.
  • Comparative Example 2 A negative electrode, a positive electrode, and a separator were prepared in the same manner as in Comparative Example 1.
  • Example 2 using an automatic laminating device different from that of Example 1, a plurality of the above positive electrodes, separators, and negative electrodes were automatically laminated in this order.
  • the automatic laminating device took out one positive electrode, one separator, and one negative electrode set at predetermined positions for each type and automatically laminated them.
  • the obtained laminate was inserted into the exterior of the laminate, and then a secondary battery was obtained in the same manner as in Example 1.
  • the number of laminated bodies was adjusted so that the initial capacity of the obtained secondary battery was 10 Ah.
  • Capacity retention rate Capacity / initial capacity (hereinafter, the ratio is referred to as "capacity retention rate") was determined.
  • the cycle characteristics of each example were evaluated according to the following criteria. The closer the capacity retention rate is to 100%, the better the cycle characteristics.
  • Table 1 shows the evaluation of cycle characteristics in each example.
  • the initial capacity was 10 Ah in all the examples.
  • the energy density obtained from the initial capacity of Example 1 was 450 Wh / kg.
  • the secondary battery of the present invention Since the secondary battery of the present invention has high energy density and capacity and excellent cycle characteristics, it has industrial applicability as a power storage device used for various purposes.

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