WO2020196042A1 - 全固体二次電池及びその製造方法 - Google Patents

全固体二次電池及びその製造方法 Download PDF

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Publication number
WO2020196042A1
WO2020196042A1 PCT/JP2020/011507 JP2020011507W WO2020196042A1 WO 2020196042 A1 WO2020196042 A1 WO 2020196042A1 JP 2020011507 W JP2020011507 W JP 2020011507W WO 2020196042 A1 WO2020196042 A1 WO 2020196042A1
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Prior art keywords
active material
electrode active
negative electrode
material layer
positive electrode
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PCT/JP2020/011507
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English (en)
French (fr)
Japanese (ja)
Inventor
真二 今井
信 小澤
鈴木　秀幸
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富士フイルム株式会社
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Priority to KR1020217031566A priority Critical patent/KR102661063B1/ko
Priority to JP2021509098A priority patent/JP7119214B2/ja
Priority to CN202080023512.3A priority patent/CN113748543A/zh
Publication of WO2020196042A1 publication Critical patent/WO2020196042A1/ja

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat 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
    • H01M4/13—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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of 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
    • H01M4/36—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
    • H01M4/386—Silicon or alloys based on silicon
    • 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
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0065—Solid electrolytes
    • H01M2300/0068—Solid electrolytes inorganic
    • 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 an all-solid-state secondary battery and a method for manufacturing the same.
  • a lithium ion secondary battery is a storage battery that has a negative electrode, a positive electrode, and an electrolyte sandwiched between the negative electrode and the positive electrode, and can be charged and discharged by reciprocating lithium ions between the two electrodes. ..
  • an organic electrolyte has been used as an electrolyte in a lithium ion secondary battery.
  • the organic electrolytic solution is liable to leak, and there is a possibility that a short circuit may occur inside the battery due to overcharging or overdischarging, and further improvement in reliability and safety is required. Under such circumstances, the development of an all-solid secondary battery using a nonflammable inorganic solid electrolyte instead of the organic electrolyte is underway.
  • the negative electrode, electrolyte, and positive electrode are all made of solid, which can greatly improve the safety or reliability of batteries using organic electrolytes, and can also extend the service life. It is said that it will be.
  • a secondary battery that reciprocates metal ions between both poles usually has an irreversible capacity, and when charged for the first time after the battery is manufactured, the amount of metal that is the source of metal ions (all-solid lithium ion secondary battery). In the case of a battery, the amount of lithium) may be reduced (leading to loss of discharge capacity) and the desired battery capacity may not be achieved.
  • As one of the measures for reducing the amount of metal by the above-mentioned initial charging there is a technique of replenishing the corresponding metal ion separately from the active material forming the negative electrode active material layer or the positive electrode active material layer.
  • Patent Document 1 describes a laminate of a positive electrode precursor containing a positive electrode active material and a specific lithium compound, a negative electrode, and a separator in a lithium ion secondary battery using a non-aqueous electrolyte solution.
  • a method of predoping lithium ions on a negative electrode by applying a voltage between a positive electrode precursor and a negative electrode under specific conditions to decompose a lithium compound in the presence of a non-aqueous electrolyte solution is described.
  • the high-load charge / discharge cycle characteristics of the lithium ion secondary battery can be improved by holding the non-aqueous electrolyte solution in the pores generated by the decomposition of the lithium compound.
  • An object of the present invention is to provide an all-solid-state secondary battery and a method for manufacturing the same, which realizes not only a high battery capacity but also a high energy density.
  • the present inventors prepare a laminate of a positive electrode active material layer containing a negative electrode active material precursor and a solid electrolyte layer, charge the laminated body, and then compress the positive electrode active material layer to obtain a battery capacity.
  • a positive electrode active material layer containing a negative electrode active material precursor and a solid electrolyte layer
  • charge the laminated body and then compress the positive electrode active material layer to obtain a battery capacity.
  • the present invention has been further studied based on these findings and has been completed.
  • a method for manufacturing an all-solid secondary battery having a solid electrolyte layer containing an inorganic solid electrolyte and a positive electrode active material layer on one surface of the solid electrolyte layer A step of forming a positive electrode active material layer on one surface of the solid electrolyte layer by using a positive electrode composition containing a positive electrode active material and a negative electrode active material precursor.
  • ⁇ 2> The method for manufacturing an all-solid-state secondary battery according to ⁇ 1>, wherein the laminate is pressurized at a pressure of 10 to 1000 MPa in the step of compressing.
  • ⁇ 3> The method for manufacturing an all-solid-state secondary battery according to ⁇ 2>, wherein the pressure is 80 MPa or more.
  • ⁇ 4> The method for manufacturing an all-solid-state secondary battery according to any one of ⁇ 1> to ⁇ 3>, wherein the charging step is performed in a state where the laminated body is pressure-constrained in the stacking direction.
  • ⁇ 5> The method for manufacturing an all-solid-state secondary battery according to any one of ⁇ 1> to ⁇ 4>, wherein the step of compressing is performed without applying a voltage to the laminated body.
  • ⁇ 6> Any of ⁇ 1> to ⁇ 5>, wherein the negative electrode active material precursor is at least one compound selected from carbonates, oxides, and hydroxides of alkali metals or alkaline earth metals.
  • ⁇ 7> The method for producing an all-solid-state secondary battery according to any one of ⁇ 1> to ⁇ 6>, wherein the all-solid-state secondary battery has a negative electrode active material layer on the other surface of the solid electrolyte layer.
  • the all-solid-state secondary according to ⁇ 7> which comprises a step of forming a negative electrode active material layer using a composition for a negative electrode containing silicon or an alloy containing a silicon element before the step of charging. How to make a battery.
  • ⁇ 9> An all-solid-state secondary battery obtained by the method for manufacturing an all-solid-state secondary battery according to any one of ⁇ 1> to ⁇ 8> above.
  • an all-solid-state secondary battery exhibiting a high battery capacity and a high energy density can be manufactured.
  • the all-solid-state secondary battery of the present invention exhibits high battery capacity and high energy density.
  • FIG. 1 is a vertical cross-sectional view schematically showing a preferred embodiment of the all-solid-state secondary battery of the present invention.
  • the numerical range represented by using “-” means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
  • an all-solid-state secondary battery (also referred to as an all-solid-state secondary battery of the present invention) manufactured by the method for manufacturing an all-solid-state secondary battery of the present invention will be described.
  • the all-solid secondary battery of the present invention has a positive electrode active material layer, a negative electrode active material layer facing the positive electrode active material layer, and a solid electrolyte layer between the positive electrode active material layer and the negative electrode active material layer.
  • the positive electrode active material layer, the solid electrolyte layer and the negative electrode active material layer are preferably adjacent to each other.
  • the negative electrode active material layer is a metal layer (precipitated by charging) in addition to the negative electrode active material layer (negative electrode active material layer in the form in which the negative electrode active material layer is formed in advance) formed in advance.
  • the negative electrode active material layer in a form in which the negative electrode active material layer is not formed in advance) is included.
  • each layer constituting the all-solid-state secondary battery may have a single-layer structure or a multi-layer structure as long as it performs a specific function.
  • the all-solid-state secondary battery of the present invention is not particularly limited as long as it has the above configuration (solid electrolyte layer between the positive electrode active material layer and the negative electrode active material layer).
  • the all-solid-state secondary battery is not particularly limited. A known configuration for the next battery can be adopted.
  • FIG. 1 is a cross-sectional view schematically showing a laminated state of each constituent layer constituting the battery for one embodiment of an all-solid-state secondary battery.
  • the negative electrode current collector 1, the negative electrode active material layer 2, the solid electrolyte layer 3, the positive electrode active material layer 4, and the positive electrode current collector 5 are laminated in this order when viewed from the negative electrode side.
  • the adjacent layers are in direct contact with each other.
  • the charging / discharging of the all-solid-state secondary battery of the present invention having such a structure is the same as that of a normal all-solid-state secondary battery except for the predoping of metal ions, but will be briefly described below.
  • the negative electrode active material precursor in the positive electrode active material layer is (oxidized) decomposed, and ions of alkali metal or alkaline earth metal (all).
  • ions of alkali metal or alkaline earth metal (all) are generated, and these ions pass through the solid electrolyte layer and move to the negative electrode side to be replenished (doped). Since this ion replenishment is performed before the use of the all-solid-state secondary battery, it is also referred to as pre-doping to distinguish it from the ion replenishment during use.
  • the metal ions accumulated in the negative electrode are returned (moved) to the positive electrode side, and the electrons generated in the negative electrode are supplied to the operating portion 6 to reach the positive electrode.
  • a light bulb is used for the operating portion 6, and the light bulb is turned on by electric discharge.
  • the negative electrode active material layer can take various forms.
  • the negative electrode active material layer that can be taken include a negative electrode active material layer containing a negative electrode active material, which will be described later, and a negative electrode active material layer containing a silicon material or a silicon-containing alloy exhibiting a high battery capacity (also referred to as Si negative electrode). ),
  • a form in which the solid electrolyte layer and the negative electrode current collector are laminated without having the lithium metal layer and the negative electrode active material layer (a form in which the negative electrode active material layer is not formed in advance) and the like can be mentioned.
  • the form of the negative electrode active material layer can be appropriately selected according to the required characteristics, manufacturing conditions, and the like.
  • metal ions belonging to Group 1 of the periodic table or Group 2 of the periodic table accumulated in the negative electrode current collector during charging.
  • Some of the metal ions (alkaline earth metal ions) belonging to the above combine with electrons to form voids on the negative electrode current collector (interface with the solid electrolyte layer or in the solid electrolyte layer) as the negative electrode active material (for example, metal).
  • the negative electrode active material layer is formed by utilizing the phenomenon of precipitation in). That is, in this form of the all-solid-state secondary battery, the metal deposited on the negative electrode current collector functions as the negative electrode active material layer.
  • lithium metal is said to have a theoretical capacity 10 times or more that of graphite, which is widely used as a negative electrode active material. Therefore, the lithium metal layer can be formed by depositing the lithium metal on the negative electrode current collector, and the thickness can be made thinner because the negative electrode active material layer is not formed (laminated) in advance, and the energy density can be increased. It becomes possible to realize a further improved all-solid-state secondary battery.
  • the all-solid-state secondary battery in which the negative electrode active material layer is not formed in advance has an uncharged mode (a mode in which the negative electrode active material is not precipitated) and a charged mode (a negative electrode active material is precipitated). Includes both aspects.
  • the all-solid secondary battery in which the negative electrode active material layer is not formed in advance means that the negative electrode active material layer is not formed in the layer forming step in the battery manufacturing, and as described above, the negative electrode active material is not formed.
  • the material layer is formed on the negative electrode current collector by charging.
  • the solid electrolyte layer 3 is an inorganic solid electrolyte (also referred to as inorganic solid electrolyte particles when it is in the form of particles) having conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, and the effects of the present invention. It contains the components described below within a range that does not impair the above, and usually does not contain the positive electrode active material and / or the negative electrode active material.
  • This solid electrolyte layer is a layer that functions as a separator that exhibits electron insulation while exhibiting the conductivity of the ions, and the solid electrolyte layer provided in the conventional all-solid secondary battery can be applied without particular limitation. ..
  • the solid electrolyte layer is formed of the particles of the inorganic solid electrolyte.
  • the content of the inorganic solid electrolyte and the like in the solid electrolyte layer is the same as the content in 100% by mass of the solid content of the solid electrolyte composition described later.
  • the positive electrode active material layer is composed of an inorganic solid electrolyte having conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a positive electrode active material, and components described later as long as the effects of the present invention are not impaired. contains. Further, in the first uncharged state of the all-solid-state secondary battery, it is one of the preferable embodiments that the negative electrode active material precursor described later is contained. The inorganic solid electrolyte, positive electrode active material, negative electrode active material precursor, etc. will be described later. The content of the positive electrode active material, the inorganic solid electrolyte, the negative electrode active material precursor, and the like in the positive electrode active material layer is the same as the content in 100% by mass of the solid content in the positive electrode composition described later.
  • the positive electrode active material layer contains the negative electrode active material precursor
  • Battery capacity can be improved.
  • by compressing the positive electrode active material layer after the decomposition reaction (crushing the voids generated by the decomposition) the positive electrode active material layer is thinned and the (volume) energy density of the all-solid secondary battery is increased. Can be done.
  • the positive electrode active material layer containing the negative electrode active material precursor is preferably applied to the above-mentioned form in which the Si negative electrode or the negative electrode active material layer is not formed in advance.
  • the silicon material or the silicon-containing alloy has a large irreversible capacity, and the capacity (movable lithium ion amount) is greatly reduced by the initial charging. Further, even in the form in which the negative electrode active material layer is not formed in advance, the capacity loss due to the initial charging becomes large as in the case of the Si negative electrode.
  • the positive electrode active material layer contains the negative electrode active material precursor, and the decomposition reaction occurs during the first charging. By doing so, it is possible to replenish the reduced metal ions (the metal ions are stored in the Si negative electrode).
  • the negative electrode active material precursor when the negative electrode active material precursor is contained in the positive electrode active material layer, expansion due to metal ion storage or expansion due to metal precipitation (volume expansion of the negative electrode active material layer) during charging is caused by the negative electrode active material layer. Since it can be canceled by the voids generated in the decomposition reaction of the precursor of the above, the destruction of the solid electrolyte layer can be prevented, and the arrival of the dendrite at the positive electrode (occurrence of a short circuit) can be suppressed. Moreover, the energy density can be improved by crushing the voids.
  • the negative electrode active material layer is a layer containing a negative electrode active material, an inorganic solid electrolyte having ionic conductivity of a metal belonging to Group 1 or Group 2 of the Periodic Table, and further a component described later. , Lithium metal layer, etc. are adopted.
  • the inorganic solid electrolyte, negative electrode active material, etc. will be described later.
  • the lithium metal layer that can form the negative electrode active material layer means a lithium metal layer, and specifically includes a layer formed by depositing or molding lithium powder, a lithium foil, a lithium vapor deposition film, and the like.
  • the negative electrode active material layer is preferably a negative electrode active material layer containing a carbonaceous material in that volume expansion and contraction due to charge and discharge are small.
  • a form in which the negative electrode active material layer is not formed in advance is preferable, and a Si negative electrode is preferable in that a high battery capacity can be achieved and the occurrence of a short circuit can be effectively prevented.
  • the negative electrode active material layer is in a form in which the Si negative electrode or the negative electrode active material layer is not formed in advance, metal ions can be replenished by the initial charging, and the battery capacity and energy density can be increased while taking advantage of the Si negative electrode and the above-mentioned form. It can be improved.
  • the content of the negative electrode active material, the inorganic solid electrolyte, and the like in the negative electrode active material layer is the same as the content in 100% by mass of the solid content in the negative electrode composition described later.
  • the thicknesses of the negative electrode active material layer, the solid electrolyte layer, and the positive electrode active material layer are not particularly limited.
  • the thickness of each layer is preferably 10 to 1,000 ⁇ m, more preferably 20 ⁇ m or more and less than 500 ⁇ m.
  • the thickness of the negative electrode active material layer in the form in which the negative electrode active material layer is not formed in advance varies depending on the amount of metal precipitated by charging, and is not uniquely determined. In the all-solid-state secondary battery, it is more preferable that the thickness of at least one of the positive electrode active material layer, the solid electrolyte layer and the negative electrode active material layer is 50 ⁇ m or more and less than 500 ⁇ m.
  • the thickness of the lithium metal layer can be, for example, 0.01 to 100 ⁇ m regardless of the thickness of the negative electrode active material layer.
  • the positive electrode current collector 5 and the negative electrode current collector 1 are preferably electron conductors.
  • either or both of the positive electrode current collector and the negative electrode current collector may be collectively referred to as a current collector.
  • a current collector As a material for forming the positive electrode current collector, in addition to aluminum, aluminum alloy, stainless steel, nickel and titanium, the surface of aluminum or stainless steel is treated with carbon, nickel, titanium or silver (a thin film is formed). Of these, aluminum and aluminum alloys are more preferable.
  • As a material for forming the negative electrode current collector in addition to aluminum, copper, copper alloy, stainless steel, nickel and titanium, carbon, nickel, titanium or silver is treated on the surface of aluminum, copper, copper alloy or stainless steel.
  • aluminum, copper, copper alloy and stainless steel are more preferable.
  • the shape of the current collector is usually a film sheet, but a net, a punched body, a lath body, a porous body, a foam body, a molded body of a fiber group, or the like can also be used.
  • the thickness of the current collector is not particularly limited, but is preferably 1 to 500 ⁇ m. It is also preferable that the surface of the current collector is made uneven by surface treatment.
  • a functional layer or a member or the like is appropriately interposed or arranged between or outside each of the negative electrode current collector, the negative electrode active material layer, the solid electrolyte layer, the positive electrode active material layer and the positive electrode current collector. You may. Further, each layer may be composed of a single layer or a plurality of layers.
  • the all-solid-state secondary battery manufactured by the method for manufacturing an all-solid-state secondary battery of the present invention may be used as an all-solid-state secondary battery with the above structure depending on the application, but is in the form of a dry battery or the like. It is also preferable to use the battery in a suitable housing.
  • the housing may be made of metal or resin (plastic). When metallic materials are used, for example, those made of aluminum alloy and stainless steel can be mentioned. It is preferable that the metallic housing is divided into a positive electrode side housing and a negative electrode side housing, and electrically connected to the positive electrode current collector and the negative electrode current collector, respectively. It is preferable that the housing on the positive electrode side and the housing on the negative electrode side are joined and integrated via a gasket for preventing a short circuit.
  • the all-solid-state secondary battery manufactured by the manufacturing method of the present invention exhibits a high battery solubility and a high (volume) energy density. That is, in the all-solid secondary battery of the present invention, the negative electrode active material layer is pre-doped with metal ions by the first charge, and the negative electrode activity formed by using a silicon material or a silicon-containing alloy having a large irreversible capacity as the negative electrode active material. Sufficient battery characteristics are exhibited even if the material layer is provided or the negative electrode active material layer is not formed in advance. In addition, it has a positive electrode active material layer in which the voids formed by the first charge are crushed, and the volume is smaller than that before the first charge, so that the energy density is high.
  • the constituent layer of the all-solid-state secondary battery is formed of solid particles, or even if the all-solid-state secondary battery is repeatedly charged and discharged (rapidly), the occurrence of a short circuit can be suppressed.
  • Such suppression of short-circuit occurrence can also be realized by adopting a layer made of graphite and a lithium metal layer as the negative electrode active material layer.
  • the all-solid-state secondary battery of the present invention exhibiting the above-mentioned excellent characteristics shall be used in a state of being pressure-constrained in the stacking direction of the constituent layers (the stacking direction of the constituent layers, usually the thickness direction of the constituent layers). Is preferable.
  • the amount of the negative electrode active material decreases during discharge, the contact between the solid electric field material layer and the negative electrode active material is maintained, and in particular, in a form in which the metal deposited on the negative electrode current collector functions as the negative electrode active material layer. Since the amount of metal deactivation (isolated metal amount) due to charge / discharge can be reduced, the decrease in battery capacity due to charge / discharge is suppressed, and excellent cycle characteristics are also exhibited.
  • the all-solid-state secondary battery of the present invention can be applied to various applications.
  • the application mode is not particularly limited, but for example, when mounted on an electronic device, a laptop computer, a pen input computer, a mobile computer, an electronic book player, a mobile phone, a cordless phone handset, a pager, a handy terminal, a mobile fax, or a mobile phone. Examples include copying, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, mini discs, electric shavers, transceivers, electronic notebooks, calculators, portable tape recorders, radios, backup power supplies, memory cards, etc.
  • Other consumer products include automobiles (electric vehicles, etc.), electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, watches, strobes, cameras, medical equipment (pacemakers, hearing aids, shoulder massagers, etc.). .. Furthermore, it can be used for various munitions and space. It can also be combined with a solar cell.
  • the production method of the present invention preferably has the following forming steps.
  • Step of forming (solid electrolyte layer) Step of forming a solid electrolyte layer using a solid electrolyte composition containing a solid electrolyte
  • This step of forming includes a step of forming the positive electrode active material layer and the following negative electrode activity. It can be performed before or after the step of forming the material layer, and each step of forming can be appropriately determined in the order of implementation according to the form and the forming method of each layer to be formed.
  • the production method of the present invention may include the following discharging steps.
  • the step of discharging may or may not be after the step of compressing, and the step of discharging is performed before the step of compressing. It is preferable not to have a step of discharging.
  • the production method of the present invention preferably has the following steps of forming.
  • Step of Forming Material Layer This forming step is preferably performed before the step of charging.
  • performing steps in order means the time ahead and after performing a certain step and another step, and another step (pause step) is performed between one step and another step. Includes.)
  • the mode in which a certain step and another step are performed in order also includes a mode in which the time, place, or practitioner is appropriately changed.
  • a solid electrolyte layer, a positive electrode active material layer, and a negative electrode active material layer are formed, respectively.
  • Each layer may be formed individually, or two or more kinds of layers may be formed collectively or sequentially as a laminated body.
  • Each layer is usually formed into a sheet shape or a plate shape, and may include a base material, another layer, or the like.
  • the base material is not particularly limited as long as it can support the solid electrolyte layer, and examples thereof include a sheet body (plate-like body) such as the material described in the above-mentioned current collector, an organic material, and an inorganic material.
  • Examples of the organic material include various polymers, and specific examples thereof include polyethylene terephthalate, polypropylene, polyethylene, and cellulose.
  • Examples of the inorganic material include glass and ceramics.
  • Examples of other layers include a protective layer (release sheet), a current collector, a coat layer, and the like.
  • the solid electrolyte layer used in a form in which the negative electrode active material layer is not formed in advance preferably has a negative electrode current collector on its surface.
  • a sheet containing a solid electrolyte layer and not having a positive electrode active material layer and a negative electrode active material layer is a solid electrolyte sheet
  • a sheet containing a negative electrode active material layer is a negative electrode sheet
  • a sheet containing a positive electrode active material layer is a positive electrode sheet. It is called.
  • the layer thickness of each layer is the same as the layer thickness of each layer described in the all-solid-state secondary battery of the present invention.
  • a solid electrolyte layer, a positive electrode active material layer, and a negative electrode active material layer are formed (prepared) when the all-solid-state secondary battery has a negative electrode active material layer in advance. ..
  • a solid electrolyte composition is prepared.
  • the solid electrolyte composition contains an inorganic solid electrolyte, and further contains a binder, a dispersion medium, a conductive auxiliary agent described later, and other components as appropriate.
  • the solid electrolyte composition is preferably a non-aqueous composition.
  • the non-aqueous composition includes not only a water-free aspect but also a form having a water content (also referred to as a water content) of 200 ppm or less.
  • the water content of the solid electrolyte layer is preferably 150 ppm or less, more preferably 100 ppm or less, and even more preferably 50 ppm or less.
  • the water content indicates the amount of water contained in the solid electrolyte composition (mass ratio to the solid electrolyte composition).
  • the water content can be determined by filtering the solid electrolyte composition with a 0.45 ⁇ m membrane filter and performing Karl Fischer titration.
  • the inorganic solid electrolyte is an inorganic solid electrolyte
  • the solid electrolyte is a solid electrolyte capable of transferring ions inside the solid electrolyte. Since it does not contain organic substances as the main ionic conductive material, it is an organic solid electrolyte (polymer electrolyte typified by polyethylene oxide (PEO), organic typified by lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), etc. It is clearly distinguished from electrolyte salts).
  • PEO polyethylene oxide
  • LiTFSI lithium bis (trifluoromethanesulfonyl) imide
  • the inorganic solid electrolyte is a solid in a steady state, it is usually not dissociated or liberated into cations and anions. In this respect, it is clearly distinguished from the electrolytic solution or the inorganic electrolyte salt (LiPF 6 , LiBF 4 , LiFSI, LiCl, etc.) in which cations and anions are dissociated or released in the polymer.
  • the inorganic solid electrolyte is not particularly limited as long as it has the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and is generally one having no electron conductivity.
  • Inorganic solid electrolytes have ionic conductivity of metals belonging to Group 1 or Group 2 of the Periodic Table.
  • a solid electrolyte material applicable to this type of product can be appropriately selected and used.
  • the inorganic solid electrolyte include (i) a sulfide-based inorganic solid electrolyte, (ii) an oxide-based inorganic solid electrolyte, (iii) a halide-based inorganic solid electrolyte, and (iV) a hydride-based solid electrolyte.
  • a sulfide-based inorganic solid electrolyte is preferable in terms of high ionic conductivity and ease of interparticle interface bonding.
  • the inorganic solid electrolyte material can be appropriately selected and used as the inorganic solid electrolyte material applied to this kind of product.
  • the all-solid-state secondary battery of the present invention is an all-solid-state lithium-ion secondary battery
  • the inorganic solid electrolyte preferably has lithium ion ionic conductivity.
  • the sulfide-based inorganic solid electrolyte contains a sulfur atom, has ionic conductivity of a metal belonging to Group 1 or Group 2 of the Periodic Table, and is electronically insulated. A compound having a property is preferable.
  • the sulfide-based inorganic solid electrolyte preferably contains at least Li, S and P as elements and has lithium ion conductivity, but other than Li, S and P may be used depending on the purpose or case. It may contain elements.
  • Examples of the sulfide-based inorganic solid electrolyte include a lithium ion conductive sulfide-based inorganic solid electrolyte satisfying the composition represented by the following formula (1).
  • L represents an element selected from Li, Na and K, with Li being preferred.
  • M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al 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 satisfy 1 to 12: 0 to 5: 1: 2 to 12: 0 to 10.
  • a1 is preferably 1 to 9, more preferably 1.5 to 7.5.
  • b1 is preferably 0 to 3, more preferably 0 to 1.
  • the 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.
  • composition ratio of each element can be controlled by adjusting the compounding ratio of the raw material compound when producing the sulfide-based inorganic solid electrolyte as described below.
  • the sulfide-based inorganic solid electrolyte may be non-crystal (glass) or crystallized (glass-ceramic), or only a part thereof may be crystallized.
  • Li-PS-based glass containing Li, P and S, or Li-PS-based 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 (for example, diphosphorus pentasulfide (P 2 S 5 )), simple phosphorus, simple sulfur, sodium sulfide, hydrogen sulfide, and lithium halide (for example). It can be produced by the reaction of at least two or more raw materials in sulfides of LiI, LiBr, LiCl) and the element represented by M (for example, SiS 2 , SnS, GeS 2 ).
  • the ratio of Li 2 S and P 2 S 5 is, Li 2 S: at a molar ratio of P 2 S 5, preferably 60: 40 ⁇ It is 90:10, more preferably 68:32 to 78:22.
  • the lithium ion conductivity can be made high.
  • the lithium ion conductivity can be preferably 1 ⁇ 10 -4 S / cm or more, and more preferably 1 ⁇ 10 -3 S / cm or more. There is no particular upper limit, but it is practical that it is 1 ⁇ 10 -1 S / cm or less.
  • Li 2 S-P 2 S 5 Li 2 S-P 2 S 5 -LiCl, Li 2 S-P 2 S 5 -H 2 S, Li 2 S-P 2 S 5 -H 2 S-LiCl, Li 2 S-LiI-P 2 S 5 , Li 2 S-LiI-Li 2 O-P 2 S 5 , Li 2 S-LiBr-P 2 S 5 , Li 2 S-Li 2 O-P 2 S 5 , Li 2 S-Li 3 PO 4- P 2 S 5 , Li 2 S-P 2 S 5- P 2 O 5 , Li 2 S-P 2 S 5- SiS 2 , Li 2 S-P 2 S 5- SiS 2- LiCl, Li 2 S-P 2 S 5- SnS, Li 2 S-P 2 S 5- Al 2 S 3 , Li 2 S-GeS 2 , Li 2 S-GeS 2 , Li 2 S-Ge
  • the mixing ratio of each raw material does not matter.
  • an amorphization method can be mentioned.
  • the amorphization method include a mechanical milling method, a solution method and a melt quenching method. This is because processing at room temperature is possible and the manufacturing process can be simplified.
  • the oxide-based inorganic solid electrolyte contains oxygen atoms, has ionic conductivity of a metal belonging to Group 1 or Group 2 of the Periodic Table, and is electronically insulated. A compound having a property is preferable.
  • the oxide-based inorganic solid electrolyte preferably has an ionic conductivity of 1 ⁇ 10 -6 S / cm or more, more preferably 5 ⁇ 10 -6 S / cm or more, and 1 ⁇ 10 -5 S / cm or more. It is particularly preferable that it is / cm or more.
  • the upper limit is not particularly limited, but it is practical that it is 1 ⁇ 10 -1 S / cm or less.
  • nb (M bb is at least one element of Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, Sn, xb satisfies 5 ⁇ xb ⁇ 10, and yb is 1 ⁇ yb.
  • zb satisfies 1 ⁇ zb ⁇ 4, mb satisfies 0 ⁇ mb ⁇ 2, nb satisfies 5 ⁇ nb ⁇ 20), Li xc Byc M cc zc Onc (M cc is). At least one or more elements of C, S, Al, Si, Ga, Ge, In, and Sn, xc satisfies 0 ⁇ xc ⁇ 5, yc satisfies 0 ⁇ yc ⁇ 1, and zc satisfies 0 ⁇ zc ⁇ .
  • Li, P and O Phosphorus compounds containing Li, P and O are also desirable.
  • lithium phosphate Li 3 PO 4
  • LiPON in which a part of oxygen of lithium phosphate is replaced with nitrogen
  • LiPOD 1 Li is Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr. , Nb, Mo, Ru, Ag, Ta, W, Pt, Au and the like (at least one selected from) and the like.
  • LiA 1 ON A 1 is at least one selected from Si, B, Ge, Al, C, Ga and the like
  • a 1 ON A 1 is at least one selected from Si, B, Ge, Al, C, Ga and the like
  • the halide-based inorganic solid electrolyte contains a halogen atom, has ionic conductivity of a metal belonging to Group 1 or Group 2 of the Periodic Table, and is electronically insulated. A compound having a property is preferable.
  • the halide-based inorganic solid electrolyte is not particularly limited, and examples thereof include compounds such as Li 3 YBr 6 and Li 3 YCl 6 described in LiCl, LiBr, LiI, ADVANCED MATERIALS, 2018, 30, 1803075. Of these, Li 3 YBr 6 and Li 3 YCl 6 are preferable.
  • the hydride-based inorganic solid electrolyte contains a hydrogen atom, has ionic conductivity of a metal belonging to Group 1 or Group 2 of the Periodic Table, and is electronically insulated. A compound having a property is preferable.
  • the hydride-based inorganic solid electrolyte is not particularly limited, and examples thereof include LiBH 4 , Li 4 (BH 4 ) 3 I, and 3 LiBH 4- LiCl.
  • the inorganic solid electrolyte is preferably particles.
  • the particle size (volume average particle size) of the inorganic solid electrolyte is not particularly limited, but is preferably 0.01 ⁇ m or more, and more preferably 0.1 ⁇ m or more.
  • the upper limit is preferably 100 ⁇ m or less, and more preferably 50 ⁇ m or less.
  • the particle size of the inorganic solid electrolyte is measured by the following procedure. Inorganic solid electrolyte particles are prepared by diluting 1% by mass of a dispersion in a 20 mL sample bottle with water (heptane in the case of a water-unstable substance).
  • the diluted dispersion sample is irradiated with 1 kHz ultrasonic waves for 10 minutes, and immediately after that, it is used for the test.
  • data was captured 50 times using a laser diffraction / scattering particle size distribution measuring device LA-920 (trade name, manufactured by HORIBA) at a temperature of 25 ° C. using a measuring quartz cell. Obtain the volume average particle size.
  • LA-920 trade name, manufactured by HORIBA
  • the content of the inorganic solid electrolyte in the solid electrolyte composition is not particularly limited, but is 50% by mass or more at 100% by mass of the solid content in terms of dispersibility, reduction of interfacial resistance, and binding property. It is preferably 70% by mass or more, and particularly preferably 90% by mass or more.
  • the upper limit is not particularly limited and may be 100% by mass, but from the same viewpoint, it is preferably 99.99% by mass or less, more preferably 99.95% by mass or less, and 99. It is particularly preferable that it is 9.9% by mass or less.
  • the solid content (solid component) refers to a component that does not disappear by volatilizing or evaporating when the solid electrolyte composition is dried at 130 ° C. for 6 hours under an atmospheric pressure of 1 mmHg and a nitrogen atmosphere. .. Typically, it refers to a component other than the dispersion medium described later.
  • the solid electrolyte composition may contain a binder that binds solid particles such as an inorganic solid electrolyte.
  • the binder include organic polymers, and known organic polymers used in the production of all-solid-state secondary batteries can be used without particular limitation. Examples of such organic polymers include fluororesins, hydrocarbon-based thermoplastic resins, acrylic resins, polyurethane resins, polyurea resins, polyamide resins, polyimide resins, polyester resins, polyether resins, polycarbonate resins, cellulose derivative resins and the like. Can be mentioned.
  • the binder is preferably particles. One type of binder may be used alone, or two or more types may be used.
  • the content of the binder in the solid content of the solid electrolyte composition is not particularly limited, but is preferably 0.1 to 10% by mass, more preferably 1 to 10% by mass, for example. 2 to 5% by mass is more preferable.
  • the solid electrolyte composition of the present invention also preferably contains a dispersion medium.
  • the dispersion medium may be any one that disperses each component contained in the solid electrolyte composition.
  • the dispersion medium is preferably a non-aqueous dispersion medium containing no water, and is usually selected from organic solvents.
  • the term "water-free" includes aspects in which the water content is 0% by mass and 0.1% by mass or less. However, the water content in the solid electrolyte composition is preferably within the above range (non-aqueous composition).
  • the organic solvent is not particularly limited, and examples thereof include organic solvents such as alcohol compounds, ether compounds, amide compounds, amine compounds, ketone compounds, aromatic compounds, aliphatic compounds, nitrile compounds, and ester compounds.
  • the dispersion medium contained in the solid electrolyte composition may be one kind or two or more kinds.
  • the content of the dispersion medium in the solid electrolyte composition is not particularly limited, and is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and particularly preferably 40 to 60% by mass.
  • the solid electrolyte composition may contain other components.
  • the other components are not particularly limited, and examples thereof include various additives.
  • the additive include a thickener, a cross-linking agent (such as one that undergoes a cross-linking reaction by radical polymerization, condensation polymerization or ring-opening polymerization), a polymerization initiator (such as one that generates an acid or radical by heat or light), and the like. It can contain a defoaming agent, a leveling agent, a dehydrating agent, an antioxidant and the like.
  • the content of the other components in the solid electrolyte composition is not particularly limited and is appropriately set.
  • the solid electrolyte composition can be prepared, for example, as a solid mixture or slurry by mixing an inorganic solid electrolyte and an appropriate binder, dispersion medium, other components and the like with, for example, various commonly used mixers. ..
  • the mixing method is not particularly limited, and can be carried out using a known mixer such as a ball mill, a bead mill, or a disc mill. Further, the mixing conditions are not particularly limited.
  • the mixed atmosphere may be any of air, dry air (dew point ⁇ 20 ° C. or lower), inert gas (for example, argon gas, helium gas, nitrogen gas) and the like. Since the inorganic solid electrolyte reacts with moisture, the mixing is preferably carried out under dry air or in an inert gas.
  • the solid electrolyte layer is not particularly limited, but is a molding method in which the solid electrolyte composition is pressure-molded, a coating drying method in which a solid electrolyte composition (slurry) containing a dispersion medium is applied and dried, and then pressure is preferably applied.
  • the method for molding the solid electrolyte composition may be any method as long as the solid electrolyte composition can be molded in a layered or film form, and various known molding methods can be applied, and press molding (for example, using a hydraulic cylinder press machine) is used. Press molding) is preferable.
  • the pressure at the time of molding is not particularly limited, but is usually preferably set in the range of 50 to 1500 MPa, more preferably set in the range of 150 to 600 MPa, and set in the range of 100 to 300 MPa. Is more preferable.
  • the molding (pressing) time may be a short time (for example, within several hours) or a long time (one day or more).
  • the solid electrolyte composition may be heated at the same time as the pressurization, but in the present invention, premolding is preferable without heating, and for example, molding is preferably performed at an environmental temperature of 10 to 50 ° C.
  • the atmosphere during molding is preferably carried out under dry air or in an inert gas.
  • Examples of the coating method of the solid electrolyte composition include wet coating methods such as spin coating coating, dip coating, slit coating, stripe coating and bar coating coating.
  • the drying temperature is not particularly limited, but is preferably 30 to 300 ° C, more preferably 60 to 250 ° C, for example. It is preferable to pressurize the coating dry layer of the solid electrolyte composition.
  • the pressurizing method and pressure are not particularly limited, and for example, a method and pressure similar to the molding method and pressure of the solid electrolyte composition can be appropriately adopted. This pressurization can also be performed, for example, after laminating the active material layer or the like.
  • a composition for a negative electrode contains a negative electrode active material, preferably an inorganic solid electrolyte, a conductive auxiliary agent, and further appropriately contains a binder, a dispersion medium, a lithium salt, and other components.
  • the negative electrode composition may be the negative electrode active material itself, and is preferably a non-aqueous composition.
  • the inorganic solid electrolyte, binder, dispersion medium and other components that can be used in the composition for the negative electrode are as described above.
  • the lithium salt those used for all-solid-state secondary batteries can be used without particular limitation.
  • the negative electrode active material used in the present invention is a substance capable of inserting and releasing ions of metal elements belonging to Group 1 or Group 2 of the periodic table.
  • the negative electrode active material is preferably one capable of reversibly inserting and releasing lithium ions.
  • the material is not particularly limited as long as it has the above characteristics, and is a carbonaceous material, an oxide of a metal or a semi-metallic element (including a composite oxide), a simple substance of lithium, a lithium alloy, or an alloy with lithium. Examples thereof include a negative electrode active material that can be converted (forms an alloy with lithium). Of these, carbonaceous materials, metalloid element oxides, metal composite oxides, or elemental lithium are preferable in terms of reliability.
  • a negative electrode active material that can be alloyed with lithium is preferable in that the capacity of the all-solid-state secondary battery can be increased.
  • the carbonaceous material used as the negative electrode active material is a material substantially composed of carbon.
  • carbon black such as acetylene black (AB), graphite (artificial graphite such as natural graphite and vapor-grown graphite), and PAN (polyacrylonitrile) -based resin or furfuryl alcohol resin.
  • Examples thereof include carbonic materials obtained by firing a resin.
  • various carbon fibers such as PAN-based carbon fibers, cellulose-based carbon fibers, pitch-based carbon fibers, vapor-grown carbon fibers, dehydrated PVA (polypoly alcohol) -based carbon fibers, lignin carbon fibers, graphitic carbon fibers and activated carbon fibers.
  • carbonaceous materials can also be divided into non-graphitizable carbonaceous materials (also referred to as hard carbon) and graphite-based carbonaceous materials depending on the degree of graphitization. Further, the carbonaceous material preferably has the interplanar spacing or density and the size of crystallites described in JP-A-62-22066, JP-A-2-6856, and JP-A-3-45473.
  • the carbonaceous material does not have to be a single material, and a mixture of natural graphite and artificial graphite described in JP-A-5-90844, graphite having a coating layer described in JP-A-6-4516, and the like should be used. You can also.
  • As the carbonaceous material hard carbon or graphite is preferably used, and graphite is more preferably used.
  • the metal or semi-metal element oxide applied as the negative electrode active material is not particularly limited as long as it is an oxide capable of storing and releasing lithium, and is a composite of a metal element oxide (metal oxide) and a metal element.
  • metal oxide metal oxide
  • examples thereof include oxides or composite oxides of metal elements and semi-metal elements (collectively referred to as metal composite oxides) and oxides of semi-metal elements (semi-metal oxides).
  • metal composite oxides oxides or composite oxides of metal elements and semi-metal elements
  • oxides of semi-metal elements semi-metal elements
  • amorphous oxides are preferable, and chalcogenite, which is a reaction product of a metal element and an element of Group 16 of the Periodic Table, is also preferable.
  • the metalloid element means an element exhibiting properties intermediate between a metalloid element and a non-metalloid element, and usually contains six elements of boron, silicon, germanium, arsenic, antimony and tellurium, and further selenium. , Polonium and astatine.
  • Amorphous means an X-ray diffraction method using CuK ⁇ rays, which has a broad scattering zone having an apex in a region of 20 ° to 40 ° in 2 ⁇ value, and a crystalline diffraction line is used. You may have.
  • the strongest intensity of the crystalline diffraction lines seen at the 2 ⁇ value of 40 ° to 70 ° is 100 times or less of the diffraction line intensity at the apex of the broad scattering band seen at the 2 ⁇ value of 20 ° to 40 °. It is preferable that it is 5 times or less, and it is particularly preferable that it does not have a crystalline diffraction line.
  • the amorphous oxide of the metalloid element or the chalcogenide is more preferable, and the elements of the groups 13 (IIIB) to 15 (VB) of the periodic table (for example).
  • Al, Ga, Si, Sn, Ge, Pb, Sb and Bi) alone or a combination of two or more (composite) oxides, or chalcogenides are particularly preferred.
  • preferable amorphous oxides and chalcogenides include, for example, Ga 2 O 3 , GeO, PbO, PbO 2 , Pb 2 O 3 , Pb 2 O 4 , Pb 3 O 4 , Sb 2 O 3 , Sb 2.
  • Negative negative active materials that can be used in combination with amorphous oxides such as Sn, Si, and Ge include carbonaceous materials that can occlude and / or release lithium ions or lithium metals, lithium alone, lithium alloys, and lithium.
  • a negative electrode active material that can be alloyed with is preferably mentioned.
  • the oxide of a metal or a metalloid element contains at least one of titanium and lithium as a constituent component from the viewpoint of high current density charge / discharge characteristics.
  • the lithium-containing metal composite oxide include lithium oxide and the metal (composite) oxide or a composite oxide of the chalcogenide, more specifically, Li 2 SnO 2.
  • the negative electrode active material for example, a metal oxide, contains a titanium element (titanium oxide).
  • Li 4 Ti 5 O 12 lithium titanate [LTO]
  • Li 4 Ti 5 O 12 has excellent rapid charge / discharge characteristics due to small volume fluctuations during storage and release of lithium ions, and electrode deterioration is suppressed and lithium ion secondary It is preferable in that the life of the battery can be improved.
  • the lithium alloy as the negative electrode active material is not particularly limited as long as it is an alloy usually used as the negative electrode active material of the secondary battery, and examples thereof include a lithium aluminum alloy.
  • the negative electrode active material that can be alloyed with lithium is not particularly limited as long as it is usually used as the negative electrode active material of the secondary battery. Such an active material has a large expansion and contraction due to charging and discharging of the all-solid-state secondary battery.
  • the active material include a negative electrode active material (alloy) having a silicon element or a tin element, and each metal such as Al and In, and a negative electrode active material having a silicon element (silicon element-containing activity) that enables a higher battery capacity. (Material) is preferable, and a silicon element-containing active material having a silicon element content of 50 mol% or more of all the constituent elements is more preferable.
  • a negative electrode containing these negative electrode active materials Si negative electrode containing a silicon element-containing active material, Sn negative electrode containing an active material containing a tin element, etc.
  • a carbon negative electrode graphite, acetylene black, etc.
  • silicon element-containing active material examples include silicon materials such as Si and SiOx (0 ⁇ x ⁇ 1), and silicon-containing alloys containing titanium, vanadium, chromium, manganese, nickel, copper, lanthanum, and the like (for example,).
  • LaSi 2 , VSi 2 , La-Si, Gd-Si, Ni-Si) or organized active material (eg LaSi 2 / Si), as well as other silicon and tin elements such as SnSiO 3 , SnSiS 3 Examples include active materials containing.
  • SiOx itself can be used as a negative electrode active material (semi-metal oxide), and since Si is generated by the operation of an all-solid secondary battery, a negative electrode active material that can be alloyed with lithium (its It can be used as a precursor substance).
  • the negative electrode active material having a tin element include Sn, SnO, SnO 2 , SnS, SnS 2 , and the active material containing the silicon element and the tin element.
  • a composite oxide with lithium oxide for example, Li 2 SnO 2 can also be mentioned.
  • the above-mentioned negative electrode active material can be used without particular limitation, but in terms of battery capacity, a negative electrode active material that can be alloyed with silicon is a preferable embodiment as the negative electrode active material.
  • a negative electrode active material that can be alloyed with silicon is a preferable embodiment as the negative electrode active material.
  • the above-mentioned silicon material or silicon-containing alloy (alloy containing a silicon element) is more preferable, and it is further preferable to contain silicon (Si) or a silicon-containing alloy.
  • the shape of the negative electrode active material is not particularly limited, but it is preferably in the form of particles.
  • the particle size (volume average particle size) of the negative electrode active material is preferably 0.1 to 60 ⁇ m.
  • a normal crusher or classifier is used to obtain a predetermined particle size.
  • a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling airflow type jet mill, a sieve and the like are preferably used.
  • wet pulverization in which water or an organic solvent such as methanol coexists can also be performed. It is preferable to perform classification in order to obtain a desired particle size.
  • the classification method is not particularly limited, and a sieve, a wind power classifier, or the like can be used. Both dry and wet classifications can be used.
  • the average particle size of the negative electrode active material particles can be measured by the same method as the above-mentioned method for measuring the volume average particle size of the inorganic solid electrolyte.
  • the chemical formula of the compound obtained by the firing method can be calculated from the inductively coupled plasma (ICP) emission spectroscopic analysis method as a measuring method and the mass difference of the powder before and after firing as a simple method.
  • ICP inductively coupled plasma
  • the surface of the negative electrode active material may be surface-coated with another metal oxide.
  • the surface coating agent include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si or Li. Specific examples thereof include spinel titanate, tantalum oxide, niobate oxide, lithium niobate compound and the like.
  • the surface of the electrode containing the negative electrode active material may be surface-treated with sulfur or phosphorus.
  • the particle surface of the negative electrode active material may be surface-treated with active light rays or an active gas (plasma or the like) before and after the surface coating.
  • the negative electrode active material may be used alone or in combination of two or more.
  • the mass (mg) (grain amount) of the negative electrode active material per unit area (cm 2 ) of the negative electrode active material layer is not particularly limited. It can be appropriately determined according to the designed battery capacity.
  • the composition for the negative electrode preferably contains a conductive auxiliary agent, and in particular, the silicon element-containing active material as the negative electrode active material is preferably used in combination with the conductive auxiliary agent.
  • the conductive auxiliary agent is not particularly limited, and those known as general conductive auxiliary agents can be used.
  • graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black, ketjen black and furnace black, amorphous carbon such as needle coke, vapor-grown carbon fibers or carbon nanotubes, which are electron conductive materials.
  • It may be a carbon fiber such as graphene or fullerene, a metal powder such as copper or nickel, or a metal fiber, and a conductive polymer such as polyaniline, polypyrrole, polythiophene, polyacetylene, or polyphenylene derivative. You may use it.
  • the active material and the conductive auxiliary agent are used in combination, among the above conductive auxiliary agents, the conductive auxiliary agent that does not insert and release Li when the battery is charged and discharged and does not function as the active material. And. Therefore, among the conductive auxiliary agents, those that can function as active materials in the active material layer when the battery is charged and discharged are classified as active materials instead of conductive auxiliary agents.
  • the shape of the conductive auxiliary agent is not particularly limited, but is preferably in the form of particles.
  • the conductive auxiliary agent one kind may be used, or two or more kinds may be used.
  • the content of the negative electrode active material in the composition for the negative electrode is not particularly limited, and is preferably 100% by mass or less, more preferably 10 to 80% by mass, and 20% by mass, based on 100% by mass of the solid content. It is more preferably to 80% by mass.
  • the total content of the inorganic solid electrolyte and the negative electrode active material in the composition for the negative electrode is preferably 5% by mass or more at 100% by mass of the solid content. It is more preferably 10% by mass or more, particularly preferably 15% by mass or more, further preferably 50% by mass or more, particularly preferably 70% by mass or more, and 90% by mass or more. Most preferably.
  • the upper limit is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, and particularly preferably 99% by mass or less.
  • the content of the conductive auxiliary agent in the composition for the negative electrode is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, based on 100 parts by mass of the solid content.
  • the contents of the binder and the dispersion medium in the composition for the negative electrode are not particularly limited, and can be, for example, the above contents in the above solid electrolyte composition.
  • the content of the lithium salt and other components in the composition for the negative electrode is not particularly limited and may be appropriately set, for example, the above content in the solid electrolyte composition.
  • composition for negative electrode can be prepared by the same method and conditions as the preparation of the above-mentioned solid electrolyte composition.
  • the negative electrode active material layer is not particularly limited, but can be prepared by the same method and conditions as those for forming the solid electrolyte layer.
  • the coated and dried composition for the negative electrode may be heated at the same time as pressurization.
  • the heating temperature is not particularly limited, but is generally in the range of 30 to 300 ° C.
  • the method for forming the negative electrode active material layer on the surface of the solid electrolyte layer on the opposite side (the other side) of the positive electrode active material layer is not particularly limited, and a usual method can be applied.
  • a method of forming a solid electrolyte layer and a negative electrode active material layer and laminating both layers and a method of forming a negative electrode active material layer or a solid electrolyte layer on the surface of the solid electrolyte layer or the negative electrode active material layer can be mentioned.
  • the method of laminating both layers is not particularly limited, and examples thereof include a method of crimping and laminating, a method of placing a negative electrode active material on the surface of a solid electrolyte layer and pressurizing it, and a method of laminating.
  • the method of pressure-bonding and laminating is not particularly limited, and examples thereof include a method of placing (arranging) the negative electrode active material layer on the surface of the solid electrolyte layer and then pressing.
  • the method and conditions of crimping and laminating or pressurizing are not particularly limited as long as both layers can be crimped.
  • the pressure may be any pressure as long as it can crimp the negative electrode active material layer, and can be set to, for example, 1 MPa or more, preferably 1 to 150 MPa, more preferably 5 to 60 MPa.
  • the crimp lamination or pressurization may be performed under heating, but in the present invention, it is preferably performed under non-heating, and more preferably performed at an environmental temperature of 0 to 50 ° C., for example.
  • the atmosphere for crimp lamination or pressurization is the same as the atmosphere at the time of preparation of the solid electrolyte composition.
  • the method of bonding is not particularly limited, and examples thereof include a method of placing (arranging) the negative electrode active material layer after applying the electrolytic solution to the surface of the solid electrolyte layer.
  • the electrolytic solution to be used is not particularly limited.
  • the method for directly forming the negative electrode active material layer or the solid electrolyte layer on the surface of the solid electrolyte layer or the negative electrode active material layer is not particularly limited, and for example, the composition for the negative electrode on the surface of the solid electrolyte layer or the negative electrode active material layer.
  • a method of applying and drying the solid electrolyte composition can be mentioned.
  • the method and conditions for coating and drying are not particularly limited, and for example, the method and conditions for coating and drying the solid electrolyte composition can be applied.
  • the negative electrode active material layer is formed by the charging step described later.
  • a compound that generates ions of a metal belonging to Group 1 or Group 2 of the periodic table for example, a positive electrode active material
  • the negative electrode active material layer can be formed by combining the ions generated from this compound with electrons in or near the negative electrode current collector and precipitating them as a metal.
  • a composition for a positive electrode is prepared.
  • the positive electrode composition contains a positive electrode active material, a negative electrode active material precursor, preferably an inorganic solid electrolyte, a conductive auxiliary agent, and further appropriately contains a binder, a dispersion medium, a lithium salt, and other components.
  • the positive electrode composition is preferably a non-aqueous composition.
  • the inorganic solid electrolyte, conductive additive, binder, dispersion medium, lithium salt and other components that can be used in the positive electrode composition are as described above.
  • the positive electrode active material used in the present invention is a substance capable of inserting and releasing ions of metal elements belonging to Group 1 or Group 2 of the periodic table.
  • a metal oxide preferably a transition metal oxide
  • the positive electrode active material is preferably one that can reversibly insert and release lithium ions.
  • the material is not particularly limited as long as it has the above-mentioned properties, and may be a transition metal oxide, an organic substance, an element that can be composited with Li such as sulfur, or a composite of sulfur and a metal.
  • the 1 (Ia) group elements of the transition metal oxide to elemental M b (Table metal periodic other than lithium, the elements of the 2 (IIa) group, Al, Ga, In, Ge , Sn, Pb, Elements such as Sb, Bi, Si, P or B) may be mixed.
  • the mixing amount is preferably 0 ⁇ 30 mol% relative to the amount of the transition metal element M a (100mol%). That the molar ratio of li / M a was synthesized were mixed so that 0.3 to 2.2, more preferably.
  • transition metal oxide examples include (MA) a transition metal oxide having a layered rock salt type structure, (MB) a transition metal oxide having a spinel type structure, (MC) a lithium-containing transition metal phosphoric acid compound, and (MD). ) Lithium-containing transition metal halide phosphoric acid compound, (ME) lithium-containing transition metal silicic acid compound, and the like.
  • transition metal oxide having a layered rock salt structure examples include LiCoO 2 (lithium cobalt oxide [LCO]), LiNi 2 O 2 (lithium nickel oxide), LiNi 0.85 Co 0.10 Al 0. 05 O 2 (Lithium Nickel Cobalt Oxide [NCA]), LiNi 1/3 Co 1/3 Mn 1/3 O 2 (Lithium Nickel Manganese Cobalt Oxide [NMC]) and LiNi 0.5 Mn 0.5 O 2 ( Lithium manganese nickel oxide).
  • LiCoO 2 lithium cobalt oxide [LCO]
  • LiNi 2 O 2 lithium nickel oxide
  • LiNi 0.85 Co 0.10 Al 0. 05 O 2 Lithium Nickel Cobalt Oxide [NCA]
  • LiNi 1/3 Co 1/3 Mn 1/3 O 2 Lithium Nickel Manganese Cobalt Oxide [NMC]
  • LiNi 0.5 Mn 0.5 O 2 Lithium manganese nickel oxide
  • (MB) Specific examples of the transition metal oxide having a spinel structure, LiMn 2 O 4 (LMO) , LiCoMnO 4, Li 2 FeMn 3 O 8, Li 2 CuMn 3 O 8, Li 2 CrMn 3 O 8 and Li 2 Nimn 3 O 8 can be mentioned.
  • Examples of the (MC) lithium-containing transition metal phosphate compound include olivine-type iron phosphate salts such as LiFePO 4 and Li 3 Fe 2 (PO 4 ) 3 , iron pyrophosphates such as LiFeP 2 O 7 , and LiCoPO 4.
  • Examples thereof include cobalt phosphates of the above and monoclinic panocycon-type vanadium phosphate salts such as Li 3 V 2 (PO 4 ) 3 (lithium vanadium phosphate).
  • (MD) as the lithium-containing transition metal halogenated phosphate compound for example, Li 2 FePO 4 F such fluorinated phosphorus iron salt, Li 2 MnPO 4 hexafluorophosphate manganese salts such as F and Li 2 CoPO 4 F
  • cobalt fluoride phosphates such as.
  • Examples of the (ME) lithium-containing transition metal silicic acid compound include Li 2 FeSiO 4 , Li 2 MnSiO 4, and Li 2 CoSiO 4 .
  • a transition metal oxide having a (MA) layered rock salt type structure is preferable, and LCO or NMC is more preferable.
  • the shape of the positive electrode active material is not particularly limited, but it is preferably in the form of particles.
  • the volume average particle size (sphere-equivalent average particle size) of the positive electrode active material is not particularly limited. For example, it can be 0.1 to 50 ⁇ m.
  • a normal crusher or classifier may be used.
  • the positive electrode active material obtained by the firing method may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.
  • the average particle size of the positive electrode active material particles can be measured by the same method as the above-mentioned method for measuring the volume average particle size of the inorganic solid electrolyte.
  • the surface of the positive electrode active material may be surface-coated with another metal oxide as in the negative electrode active material.
  • the positive electrode active material one type may be used alone, or two or more types may be used.
  • the mass (mg) (grain amount) of the positive electrode active material per unit area (cm 2 ) of the positive electrode active material layer is not particularly limited. It can be appropriately determined according to the designed battery capacity.
  • the negative electrode active material precursor is a compound that generates (releases) ions (metal ions) of metal elements belonging to Group 1 or Group 2 of the periodic table in the positive electrode active material layer by a charging step described later. ..
  • the generated metal ions reach the negative electrode active material layer or the like by charging the all-solid-state secondary battery and pre-dope the negative electrode active material layer.
  • metal ions reach the negative electrode current collector and combine with electrons to precipitate as a metal, and the negative electrode active material layer is pre-doped.
  • the negative electrode active material precursor is not particularly limited as long as it has such characteristics or functions, and examples thereof include compounds containing the above metal elements, but lithium as a supporting electrolyte used as a material for an all-solid secondary battery. It differs from salt in that it releases lithium ions during the first charge and decomposes, and does not contribute to the release of lithium ions during the next charge.
  • the negative electrode active material precursor is a compound different from the positive electrode active material in that lithium ions cannot be reversibly inserted and released by charging and discharging.
  • the negative electrode active material precursor is preferably an inorganic compound containing the above metal element, more preferably an inorganic salt that generates the above metal ion and an anion, and carbonate or oxidation of the above metal element (alkali metal or alkaline earth metal). Substances or hydroxides are more preferred, and compounds selected from carbonates are particularly preferred.
  • the inorganic salt is not particularly limited, but one that generates a gas by decomposition at normal temperature and pressure, preferably in a charging environment is preferable. For example, carbonates generate metal element ions and carbonate ions by oxidative decomposition.
  • the generated metal element ions serve as a constituent material of the negative electrode active material layer, and the carbonate ions are changed to carbon dioxide gas and released (disappeared) from the positive electrode active material layer to the outside. Therefore, the carbonate does not remain in the positive electrode active material layer including the decomposed product, and the deterioration of the battery characteristics (energy density) due to the inclusion of the carbonate can be avoided.
  • the all-solid-state secondary battery is an all-solid-state lithium-ion secondary battery, lithium is preferable as the metal element forming the negative electrode active material precursor.
  • the negative electrode active material precursor examples include inorganic salts of the above metal elements such as carbonates, oxides, hydroxides and halides, and organic salts such as the above metal element carboxylates (for example, oxalates). Can be mentioned.
  • Specific examples of the lithium element-containing compound (lithium salt) as the negative electrode active material precursor include lithium carbonate, lithium oxide, lithium hydroxide, lithium fluoride, lithium chloride, lithium oxalate, and lithium iodide.
  • lithium nitride, lithium sulfide, lithium phosphate, lithium nitrate, lithium sulfate, lithium phosphate, lithium oxalate, lithium formate, lithium acetate and the like examples thereof include lithium carbonate, lithium oxide or lithium hydroxide in the air. Lithium carbonate is more preferable because it can be handled safely (low moisture absorption).
  • the positive electrode composition may contain one kind of negative electrode active material precursor or two or more kinds.
  • the average particle size of the negative electrode active material precursor is not particularly limited, but is preferably 0.01 to 10 ⁇ m, and more preferably 0.1 to 1 ⁇ m.
  • the average particle size is a value measured in the same manner as the average particle size of the above-mentioned inorganic solid electrolyte particles.
  • the content of the positive electrode active material in the composition for the positive electrode is not particularly limited, and is preferably 10 to 95% by mass, more preferably 30 to 90% by mass, and further 50 to 85% by mass in terms of solid content of 100% by mass. It is preferable, and 55 to 80% by mass is particularly preferable.
  • the positive electrode composition contains an inorganic solid electrolyte
  • the total content of the inorganic solid electrolyte and the positive electrode active material in the positive electrode composition is preferably 5% by mass or more at a solid content of 100% by mass. It is more preferably 10% by mass or more, particularly preferably 15% by mass or more, further preferably 50% by mass or more, particularly preferably 70% by mass or more, and 90% by mass or more. Most preferably.
  • the upper limit is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, and particularly preferably 99% by mass or less.
  • the content of the negative electrode active material precursor in the positive electrode composition varies depending on the amount of ions of the metal element to be replenished, and is not uniquely determined. It is more preferably 5 to 30% by mass, and even more preferably 7 to 20% by mass.
  • the total content of the positive electrode active material and the negative electrode active material precursor in the positive electrode composition is not particularly limited and is preferably 70 to 90% by mass.
  • the content of the conductive auxiliary agent in the composition for the positive electrode is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, based on 100 parts by mass of the solid content.
  • the contents of the binder and the dispersion medium in the positive electrode composition are not particularly limited, and can be, for example, the above contents in the above solid electrolyte composition.
  • the content of the other component in the composition for the positive electrode is not particularly limited and may be set as appropriate, and may be, for example, the above-mentioned content described in the solid electrolyte composition.
  • the positive electrode composition can be prepared by the same method and conditions as those for preparing the solid electrolyte composition.
  • the positive electrode active material layer is not particularly limited, but can be prepared by the same method and conditions as those for forming the solid electrolyte layer. In forming the positive electrode active material layer, it is preferable to heat the coated and dried positive electrode composition at the same time as pressurization. The heating temperature is not particularly limited, but is generally in the range of 30 to 300 ° C.
  • the method for forming the positive electrode active material layer on the surface of the solid electrolyte layer on the opposite side (one side) of the negative electrode active material layer is not particularly limited, and a usual method can be applied.
  • a method of forming a solid electrolyte layer and a positive electrode active material layer and laminating both layers, and a method of forming a positive electrode active material layer or a solid electrolyte layer on the surface of the solid electrolyte layer or the positive electrode active material layer can be mentioned.
  • a method for forming the positive electrode active material layer on one surface of the solid electrolyte layer a positive electrode active material, a positive electrode active material layer or a positive electrode composition is used instead of the negative electrode active material, the negative electrode active material layer or the negative electrode composition. Except for this, a method similar to the method of forming the negative electrode active material layer on the other surface of the solid electrolyte layer can be mentioned.
  • the steps of forming the solid electrolyte layer and the positive electrode active material layer are performed to prepare a laminate containing the positive electrode active material layer and the solid electrolyte layer.
  • the all-solid secondary battery has a mode in which the negative electrode active material layer is formed in advance
  • a step of further forming the negative electrode active material layer is performed, and a laminate including the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer is performed.
  • the laminate thus obtained is an all-solid-state secondary battery before initial charging and compression, and is also referred to as an all-solid-state secondary battery precursor.
  • the charging conditions may be any conditions as long as the negative electrode active material precursor in the positive electrode active material layer can be oxidatively decomposed, and examples thereof include the following conditions.
  • the charging step is preferably performed in an open state rather than in a sealed laminate. The atmosphere at this time is the same as that at the time of preparing the solid electrolyte composition.
  • the charging step is preferably performed by pressure-constraining the laminated body in the laminating direction. As a result, problems due to volume fluctuation of the negative electrode active material layer (for example, damage to the solid electrolyte layer) can be suppressed.
  • the pressure at this time is not particularly limited, but is preferably 0.05 MPa or more, and more preferably 1 MPa.
  • the upper limit may be a pressure that does not compress the positive electrode active material layer, and is preferably less than 10 MPa, more preferably 8 MPa or less, for example.
  • charging may be performed once or multiple times.
  • the negative electrode active material precursor in the positive electrode active material layer is oxidatively decomposed to generate metal ions and anions.
  • the generated metal ions move to or near the negative electrode active material layer and dope the negative electrode active material layer.
  • the anions may remain in the positive electrode active material layer, but are preferably changed to a gas and released to the outside of the laminate.
  • predoping can be safely and concisely performed without using a lithium metal or the like. In this way, when charging is completed, voids derived from the oxidatively decomposed negative electrode active material precursor are generated in the positive electrode active material layer.
  • the void ratio in the positive electrode active material layer after charging is the type or particle size of the positive electrode active material, the formation conditions of the positive electrode active material layer, and the negative electrode active material. Since it varies depending on the type, particle size, content, etc. of the precursor, it is not uniquely determined, but it can be, for example, 5 to 30%, preferably 15 to 25%.
  • the porosity of the positive electrode active material layer is measured by the following method.
  • a negative electrode current collector or the like that can serve as a scaffold for precipitating metal ions belonging to Group 1 or Group 2 of the periodic table can be appropriately used. ..
  • this charging step not only the doping by the decomposition of the negative electrode active material precursor but also the negative electrode active material layer is formed.
  • a step of discharging the laminate can also be performed.
  • the discharge conditions are not particularly limited, and examples thereof include the following conditions. Current: 0.05 to 1 mA / cm 2 Voltage: 2.5-3.0V Charging time: 1 to 20 hours Temperature: 25 to 60 ° C
  • the discharge step is preferably performed with the laminate open because the anions of the negative electrode active material precursor can be released to the outside of the laminate.
  • the atmosphere at this time is the same as that at the time of preparing the solid electrolyte composition.
  • the step of discharging is preferably performed by restraining the laminated body under pressure in the laminating direction. As a result, the contact between the current collector and the electrode layer can be maintained.
  • the pressure at this time is not particularly limited and can be set in the above pressure range in the charging step, and may be the same as or different from the pressure in the charging step.
  • the discharge may be performed once or a plurality of times.
  • the metal ions are generated from the negative electrode active material layer or its vicinity and reach the positive electrode active material layer.
  • the metal ion and the positive electrode active material incorporating the metal ion do not completely fill the voids derived from the negative electrode active material precursor, and the positive electrode active material layer has voids that are crushed in the compression step described later. (Remaining).
  • the porosity of the positive electrode active material layer after discharge is not particularly limited, but can be, for example, 10% or more, preferably 20% or more.
  • the metal precipitated by the charging step is ionized and moved to the positive electrode active material layer by the discharging step (the volume of the negative electrode active material layer is reduced).
  • initial charging charging by the charging step
  • discharging by the discharging step is called initial discharging.
  • initialization initial charge and the initial discharge are collectively referred to as initialization, and the initialization may be performed in one cycle or a plurality of cycles with one initial charge and one initial discharge as one cycle.
  • a step of pressurizing and compressing the positive electrode active material layer is then performed.
  • the voids formed in the positive electrode active material layer after charging or the voids remaining in the positive electrode active material layer after discharge are crushed (crushed), and the positive electrode active material layer is thinned (densified). To do.
  • the total thickness (volume) of the all-solid-state secondary battery is reduced, and the energy density is improved.
  • the positive electrode active material layer In the step of compression, it is sufficient that at least the positive electrode active material layer can be compressed, but in consideration of compressing the positive electrode active material layer after charging, the positive electrode activity is activated by pressurizing the above-mentioned laminate as the all-solid-state secondary battery precursor. It is preferable to compress the material layer.
  • the method of pressurizing and compressing the positive electrode active material layer is not particularly limited, and various known pressurizing methods can be applied, and press pressurization (for example, press pressurization using a hydraulic cylinder press machine) is preferable.
  • the pressure in this step is not particularly limited as long as it can crush the voids, and is preferably higher than the pressure constraint in the charging step.
  • the pressure is appropriately determined according to the type or content of the positive electrode active material, the amount of voids, and the like, but is preferably set in the range of, for example, 10 to 1000 MPa.
  • the lower limit of the pressure is more preferably 40 MPa or more, further preferably 50 MPa or more, particularly preferably 60 MPa or more, most preferably 80 MPa or more, and the upper limit is more preferably 1000 MPa or less, further preferably 750 MPa or less.
  • the pressing time is not particularly limited, and may be a short time (for example, within several hours) or a long time (one day or more).
  • the positive electrode active material layer may be heated at the same time as pressure compression, but in the present invention, pressure compression is preferably performed without heating, and for example, pressure compression is preferably performed at an environmental temperature of 10 to 50 ° C. ..
  • the atmosphere during pressure compression is not particularly limited, and examples thereof include a mixed atmosphere of the solid electrolyte composition.
  • the step of compressing is preferably performed without applying a voltage (not charging / discharging) to at least the positive electrode active material layer, usually the all-solid-state secondary battery precursor.
  • a voltage not charging / discharging
  • the term "no voltage is applied” includes a mode in which no voltage is applied to the positive electrode active material layer or the like, and a mode in which a voltage of 2.5 to 3.0 V corresponding to the final discharge voltage is applied. To do.
  • the compression of the positive electrode active material layer is performed until the porosity of the positive electrode active material layer after compression becomes smaller than the porosity of the positive electrode active material layer after charging.
  • This compression is ideally performed until the voids derived from the negative electrode active material precursor are completely crushed (until the void ratio of the positive electrode active material layer before charging is reached), but in reality, before charging. It is carried out until the vicinity of the void ratio of the positive electrode active material layer of.
  • the porosity of the positive electrode active material layer before charging is compressed to 1.5%, preferably 1%, and more preferably 0.5% higher than the porosity.
  • This compression step differs from the pressure constraint preferably applied when using an all-solid-state secondary battery in that the positive electrode active material layer is compressed (the voids are crushed).
  • an all-solid-state secondary battery when manufacturing an all-solid-state secondary battery, a laminate having a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer depending on the form of the all-solid-state secondary battery (all-solid-state secondary battery precursor) is used. It is not pressurized with such a pressure that the layer is compressed. This is because if there are voids in the negative electrode active material layer and the positive electrode active material layer, cracks or cracks occur in the solid electrolyte layer existing between the two layers, and the battery does not function sufficiently as a secondary battery.
  • the step of compressing the positive electrode active material layer is performed after the step of charging, voids derived from the negative electrode active material precursor are formed in the positive electrode active material layer of the laminated body to be compressed.
  • the voids in the negative electrode active material layer have hardly increased since the formation of the negative electrode active material layer.
  • the production method of the present invention in which the amount of voids is set for the positive electrode active material layer and the negative electrode active material layer and the laminate is pressed, the positive electrode active material layer is formed without cracking or cracking in the solid electrolyte layer. Can be compressed. The occurrence of cracks in the solid electrolyte layer can be suppressed more effectively if the discharge step is not performed immediately before the compression step (the charging step and the compression step are performed without interposing the discharging step). ..
  • the compression step is carried out to produce an initial charge, preferably an initialized all-solid-state secondary battery.
  • This all-solid-state secondary battery exhibits high battery capacity and high energy density, as described above.
  • lithium sulfide Li 2 S, Aldrich Corp., purity> 99.98%) 2.42 g, diphosphorus pentasulfide (P 2 S 5, Aldrich Co., purity> 99%) 3.90 g were weighed, charged into an agate mortar, using an agate pestle and mixed for 5 minutes.
  • Example 1 an all-solid-state secondary battery having a positive electrode active material layer containing a negative electrode active material precursor and a Si negative electrode (negative electrode active material layer) was manufactured.
  • Macol registered trademark
  • the prepared composition for a negative electrode was wet-coated on a copper foil having a thickness of 8 ⁇ m at a basis weight of 2 mg / diameter of 10 mm, dried at 100 ° C., and temporarily pressed at 180 MPa to form a Si negative electrode active material layer. .. In this way, a negative electrode sheet having a copper foil and a Si negative electrode active material layer (thickness 30 ⁇ m) was produced.
  • the Si negative electrode active material layer of the disk-shaped negative electrode sheet punched from the prepared negative electrode sheet into a disk shape having a diameter of 10 mm is in contact with the surface of the disk-shaped solid electrolyte sheet punched from the solid electrolyte sheet into a disk shape having a diameter of 10 mm.
  • the negative electrode sheet was laminated on the solid electrolyte sheet, and the pressure was set to 24 MPa at 25 ° C. under an argon gas atmosphere, and the pressure was applied for 1 minute. In this way, a negative electrode sheet on which the solid electrolyte layer was laminated was produced.
  • a positive electrode sheet composed of a positive electrode current collector and a positive electrode active material layer was produced.
  • -Preparation of positive electrode composition 66 zirconia beads with a diameter of 5 mm were placed in a zirconia 45 mL container (manufactured by Fritsch), and 2.0 g of Li-PS-based glass synthesized in Synthesis Example 1 above and styrene-butadiene rubber (product code 182907, Aldrich). 0.1 g and 22 g of octane as a dispersion medium were added. After that, this container was set in a planetary ball mill P-7 manufactured by Fritsch, and stirred at a temperature of 25 ° C.
  • the positive electrode composition obtained above is applied to an aluminum foil having a thickness of 20 ⁇ m as a current collector at a basis weight of 15 mg / diameter of 10 mm by a baker-type applicator, heated at 80 ° C. for 2 hours, and then the positive electrode is used.
  • the composition for use was dried.
  • the composition for the positive electrode layer dried to a predetermined density was pressurized (600 MPa, 1 minute) while heating (120 ° C.). In this way, a positive electrode sheet having an aluminum foil and a positive electrode active material layer (thickness 110 ⁇ m) was produced.
  • a positive electrode active material layer of a disk-shaped positive electrode sheet punched into a disk shape having a diameter of 10 mm from the produced positive electrode sheet, and an electrolytic solution for a lithium ion battery are applied to the surface of the solid electrolyte layer of the disk-shaped negative electrode sheet on which a solid electrolyte layer is laminated. It was attached by applying a liquid mixed with polyethylene oxide (PEO).
  • PEO polyethylene oxide
  • Comparative Example 1 An all-solid-state secondary battery was manufactured in the same manner as in Example 1 except that the pressure in the compression step was set to 8 MPa.
  • the positive electrode active material layer in this all-solid-state secondary battery had a porosity of 7% and was not compressed (thinned) before and after the step of compressing.
  • Comparative Example 2 an all-solid-state secondary battery having a positive electrode active material layer containing no negative electrode active material precursor and a Si negative electrode (Si negative electrode active material layer) was manufactured.
  • the following composition was used for the positive electrode (the production of the positive electrode sheet is the same as that of Example 1), and the step of compressing was not performed.
  • An all-solid-state secondary battery having a positive electrode active material layer containing no negative electrode active material precursor was manufactured in the same manner as in the production of the all-solid-state secondary battery of Example 1.
  • each all-solid-state secondary battery produced above was constrained with a restraining pressure of 8 MPa in the stacking direction, 0.09 mA / cm 2 , final voltage 2.5 V, charging time 18 hours. The initial discharge was performed under the conditions of the temperature of 25 ° C. Next, each all-solid-state secondary battery was charged / discharged (rapidly) under the following conditions, and a charge / discharge cycle characteristic test (severe acceleration condition) was carried out. (conditions) Was charged at a current density of 2.2 mA / cm 2 to 4.25 V, was repeated seven cycles charge-discharge cycle for the discharge at a current density of 2.2 mA / cm 2 to 2.5V as one cycle.
  • Example 1 The all-solid-state secondary battery of Example 1 had a discharge capacity of 7 cycles equivalent to that of Comparative Example 2 (having the same basis weight of the positive electrode active material) using 7.9 g of the positive electrode active material NCA. As a result, it was confirmed that this all-solid-state secondary battery showed the same discharge capacity as that of Comparative Example 2, and that the battery volume was reduced due to the thinning of the positive electrode active material layer, and the volumetric energy density was improved. .. In addition, the charge / discharge efficiency of all 7 cycles was stable at 99%. As a result, it can be seen that the occurrence of a short circuit can be suppressed.
  • the interface peeling between the negative electrode active material layer and the solid electrolyte layer due to the volume expansion and contraction of the negative electrode active material layer can be prevented, and a high discharge capacity is maintained.
  • the cross-sectional portion of the solid electrolyte layer was observed by SEM after performing ion beam milling, the occurrence of cracks and cracks could not be confirmed.
  • Comparative Example 1 In the all-solid-state secondary battery of Comparative Example 1, since the positive electrode active material layer was not compressed, improvement in volume energy density could not be confirmed. Comparative Example 2 In the all-solid-state secondary battery of Comparative Example 2, since the positive electrode active material layer does not contain the negative electrode active material precursor, it is not possible to compensate for the decrease in the amount of lithium metal in the Si negative electrode active material layer, and the discharge capacity is high. Not enough. Moreover, since the thickness of the positive electrode active material layer is constant (unchanged), improvement in volumetric energy density could not be confirmed.

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