Method for producing all-solid-state battery

Abstract

The purpose of the present invention is to provide a means for obtaining an all-solid-state battery excellent in terms of both capacity and fast charging characteristics.　The present invention provides a method for producing an all-solid-state battery including a power generation element encapsulated in a battery outer case, the power generation element comprising: a positive electrode including a positive-electrode active material layer comprising a positive-electrode active material and a first solid electrolyte; a negative electrode including a negative-electrode active material layer comprising a negative-electrode active material; and a solid electrolyte layer interposed between the positive electrode and the negative electrode and comprising a second solid electrolyte. The method includes: a chemical conversion step which includes a step for initially charging the power generation element in an inert gas atmosphere; and a step in which, after the chemical conversion step, the power generation element is encapsulated in the battery outer case under reduced pressure.

Description

Manufacturing method for all-solid-state batteries

[0001] The present invention relates to a method for manufacturing an all-solid-state battery.

[0002] In recent years, research and development into all-solid-state batteries using oxide- or sulfide-based solid electrolytes has been actively pursued. Solid electrolytes are materials primarily composed of ionic conductors capable of conducting ions in a solid state. Therefore, all-solid-state batteries have the advantage of not, in principle, encountering the various problems associated with flammable organic electrolytes that occur in conventional liquid-based secondary batteries using nonaqueous electrolytes. Furthermore, the use of high-potential, high-capacity positive electrode materials and high-capacity negative electrode materials generally leads to significant improvements in the output density and energy density of batteries.

[0003] A typical all-solid-state battery has a structure in which a power generating element, which is formed by stacking a positive electrode, a solid electrolyte layer, and a negative electrode in this order, is sealed inside a battery exterior. In manufacturing an all-solid-state battery, in order to improve battery performance, the power generating element is initially charged in an oxygen-containing atmosphere and then vacuum-sealed (JP 2017-126422 A).

[0004] However, according to the investigations of the present inventors, it has been found that when the power generating element of an all-solid-state battery is initially charged in an oxygen-containing atmosphere, as described in JP 2017-126422 A, the charge-discharge efficiency may decrease, and when the power generating element is initially charged under reduced pressure, sufficient rapid charge characteristics may not be obtained.

[0005] Therefore, an object of the present invention is to provide a means for obtaining an all-solid-state battery that is excellent in both capacity and rapid charging characteristics.

[0006] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found that the above-mentioned problems can be solved by performing an initial charge in an inert gas atmosphere and then sealing the battery element under reduced pressure, which has led to the completion of the present invention.

[0007] That is, one aspect of the present invention is a method for manufacturing an all-solid-state battery in which a power generating element including: a positive electrode having a positive electrode active material layer containing a positive electrode active material and a first solid electrolyte; a negative electrode having a negative electrode active material layer containing a negative electrode active material; and a solid electrolyte layer interposed between the positive electrode and the negative electrode and containing a second solid electrolyte is sealed inside a battery exterior body, the method comprising: a chemical formation step including a step of initially charging the power generating element under an inert gas atmosphere; and a step of, after the chemical formation step, sealing the power generating element inside the battery exterior body under reduced pressure.

[0008] FIG. 1 is a cross-sectional view schematically illustrating the overall structure of a stacked-type (internal parallel connection type) all-solid-state lithium secondary battery (stacked-type secondary battery) according to one embodiment of the present invention.

[0009] One aspect of the present invention is a method for manufacturing an all-solid-state battery in which a power generating element including a positive electrode having a positive electrode active material layer containing a positive electrode active material and a first solid electrolyte, a negative electrode having a negative electrode active material layer containing a negative electrode active material, and a solid electrolyte layer interposed between the positive electrode and the negative electrode and containing a second solid electrolyte is sealed inside a battery exterior, the method comprising: a chemical formation step including a step of initially charging the power generating element in an inert gas atmosphere; and a step of, after the chemical formation step, sealing the power generating element inside the battery exterior under reduced pressure. The method for manufacturing an all-solid-state battery according to this aspect can produce an all-solid-state battery having excellent both capacity and rapid charging characteristics.

[0010] As described in JP 2017-126422 A, in the manufacture of an all-solid-state battery having a structure in which a power generating element, which is formed by stacking a positive electrode, a solid electrolyte layer, and a negative electrode in this order, is sealed inside a battery outer casing, a process is performed in which the power generating element is initially charged in an oxygen-containing atmosphere and then vacuum-sealed. However, it has been found that initially charging the power generating element in an oxygen-containing atmosphere can sometimes result in a decrease in charge / discharge efficiency. This is thought to be due to oxidation or deterioration of the positive electrode active material, negative electrode active material, solid electrolyte, etc., caused by the initial charging in an oxygen-containing atmosphere.

[0011] On the other hand, it has been found that when the power generating element is initially charged under reduced pressure, the charge / discharge characteristics are improved, but the resistance increases, and sufficient rapid charge characteristics may not be obtained. In contrast, in the manufacturing method of the present invention, the power generating element is initially charged under an inert gas atmosphere and then sealed under reduced pressure. This suppresses the increase in resistance and improves the rapid charge characteristics.

[0012] In a reduced pressure (reducing) atmosphere, a side reaction between the solid electrolyte and the positive electrode active material (e.g., reduction of the positive electrode active material by the solid electrolyte) may occur at the contact point between the positive electrode active material and the solid electrolyte. As a result, when the initial charge is performed under reduced pressure, a layer of reactants due to the side reaction is formed on the surface of the positive electrode active material particles, leading to a significant increase in resistance. For example, in a metal oxide positive electrode active material, the metal oxide is reduced to form a metal layer on the surface of the positive electrode active material particles, which can increase resistance. However, when the initial charge is performed under an inert gas atmosphere, the positive electrode active material forms a structural change layer on the particle surface during structural change associated with charging. The increase in resistance due to the formation of this structural change layer is negligible compared to the increase in resistance during the initial charge under a reduced pressure atmosphere. Furthermore, the formation of the structural change layer can suppress further side reactions between the positive electrode active material and the solid electrolyte.

[0013] Furthermore, the inventors discovered that after initial charging in an inert gas atmosphere, neither a decrease in capacity nor an increase in resistance occurs even under reduced pressure. They also discovered that rapid charging characteristics can be improved by reducing the pressure inside the battery exterior after initial charging in an inert gas atmosphere. By reducing the pressure inside the battery exterior after initial charging in an inert gas atmosphere, the power generating element is uniformly constrained by atmospheric pressure in the stacking direction of the battery all the way to its edges. This is thought to reduce the likelihood of dendrite shorts due to heterogeneous reactions, even during charging and discharging at high current densities, thereby improving rapid charging characteristics.

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate explanations will be omitted. Furthermore, the dimensional proportions in the drawings are exaggerated for the convenience of explanation and may differ from the actual proportions.

[0015] FIG. 1 is a cross-sectional view schematically illustrating the overall structure of a stacked-type (internal parallel connection type) all-solid-state lithium secondary battery (hereinafter also simply referred to as a "stacked-type secondary battery") according to one embodiment of the present invention. FIG. 1 shows a cross section of a stacked-type secondary battery during charging, which is a lithium deposition-type all-solid-state battery. The stacked-type secondary battery 10a shown in FIG. 1 has a structure in which a substantially rectangular power generating element 21, where the actual charge / discharge reaction proceeds, is sealed inside a laminate film 29, which is a battery exterior. Here, the power generating element 21 has a structure in which a negative electrode, a solid electrolyte layer 17, and a positive electrode are stacked. The negative electrode has a structure in which a negative electrode current collector 11' and a negative electrode active material layer 13 made of lithium metal deposited on the surface of the negative electrode current collector 11' are stacked. A negative electrode intermediate layer 14 is disposed adjacent to the surface of the negative electrode active material layer 13 facing the solid electrolyte layer 17. The positive electrode has a structure in which a positive electrode active material layer 15 is disposed on the surface of a positive electrode current collector 11". The negative electrode, solid electrolyte layer, and positive electrode are laminated in this order, with the negative electrode intermediate layer 14 and the positive electrode active material layer 15 facing each other with the solid electrolyte layer 17 interposed therebetween. As a result, adjacent negative electrodes, solid electrolyte layers, and positive electrodes constitute one unit cell layer 19. Therefore, the stacked secondary battery 10a shown in FIG. 1 can be said to have a structure in which a plurality of unit cell layers 19 are laminated and electrically connected in parallel. A negative electrode current collector 25 and a positive electrode current collector 27 that are electrically connected to the respective electrodes (negative electrode and positive electrode) are attached to the negative electrode current collector 11' and the positive electrode current collector 11", respectively, and are structured so as to be sandwiched between the ends of the laminate film 29 and extended to the outside of the laminate film 29. A constraining pressure is applied to the stacked secondary battery 10a in the stacking direction of the power generating element 21 by a pressure member (not shown). Therefore, the volume of the power generating element 21 is kept constant.

[0016] The main components of the all-solid-state battery according to this embodiment will be described below.

[0017] [Current Collector] The current collector (negative electrode current collector, positive electrode current collector) has the function of mediating the movement of electrons from the electrode active material layer (negative electrode active material layer, positive electrode active material layer). There are no particular restrictions on the material that constitutes the current collector. Examples of materials that can be used for the current collector include metals such as aluminum, nickel, iron, stainless steel, titanium, and copper, as well as conductive resins. There are also no particular restrictions on the thickness of the current collector, but an example is 10 to 100 μm.

[0018] [Positive Electrode Active Material Layer] The positive electrode active material layer contains a positive electrode active material and a solid electrolyte, and may contain a binder and a conductive additive as needed.

[0019] The positive electrode active material has the function of releasing ions such as lithium ions during charging and absorbing ions such as lithium ions during discharging. As the positive electrode active material, a metal oxide is preferred because the effects of the present invention can be more significantly obtained. Examples of the positive electrode active material include LiCoO ２ , LiMnO ２ , LiNiO ２ , LiVO ２ , Li(Ni-Mn-Co)O ２ Layered rock salt active materials such as LiMn ２ O ４ , LiNi ０．５ Mn １．５ O ４ Spinel-type active materials such as LiFePO ４ , LiMnPO ４ Olivine type active materials such as Li ２ FeSiO ４ , Li ２ MnSiO ４ Examples of metal oxides include Si-containing active materials such as Li ４ Ti ５ O １２Among these, composite oxides containing lithium and nickel (lithium nickel composite oxides) are preferably used. When a metal oxide containing nickel, such as lithium nickel composite oxide, comes into contact with a solid electrolyte under a reducing atmosphere such as a reduced pressure, reduction of nickel oxide to nickel occurs easily, and therefore deactivation of the positive electrode active material easily proceeds, and resistance is likely to increase. Therefore, the effects of the present invention can be obtained more significantly. Examples of lithium nickel composite oxides include Li(Ni—Mn—Co)O ２ Also, those in which some of these transition metals have been replaced with other elements (hereinafter also simply referred to as "NMC composite oxides") can be preferably used. NMC composite oxides have a layered crystal structure in which lithium atomic layers and transition metal (Mn, Ni, and Co) atomic layers (orderly arranged) are alternately stacked with oxygen atomic layers interposed therebetween, and contain one Li atom per transition metal M atom, so that the amount of Li that can be extracted is twice that of spinel lithium manganese oxides, i.e., the supply capacity is doubled, resulting in high capacity.

[0020] As described above, the NMC composite oxide also includes composite oxides in which a portion of the transition metal element is substituted with another metal element. In this case, the other element may be Ti, Zr, Nb, W, P, Al, Mg, V, Ca, Sr, Cr, Fe, B, Ga, In, Si, Mo, Y, Sn, V, Cu, Ag, or Zn, preferably Ti, Zr, Nb, W, P, Al, Mg, V, Ca, Sr, or Cr, more preferably Ti, Zr, P, Al, Mg, or Cr, and even more preferably Ti, Zr, Al, Mg, or Cr from the viewpoint of improving cycle characteristics.

[0021] Since the NMC composite oxide has a high theoretical discharge capacity, it is preferable to use the NMC composite oxide represented by the general formula (1): Li ａ Ni ｂ Mn ｃ Co ｄ M ｘ O ２(wherein, a, b, c, d, and x satisfy 0.98≦a≦1.2, 0.6≦b≦0.9, 0<c≦0.4, 0<d≦0.4, 0≦x≦0.3, and b+c+d+x=1; and M is at least one element selected from Ti, Zr, Nb, W, P, Al, Mg, V, Ca, Sr, and Cr), where a represents the atomic ratio of Li, b represents the atomic ratio of Ni, c represents the atomic ratio of Mn, d represents the atomic ratio of Co, and x represents the atomic ratio of M. Furthermore, in the all-solid-state battery according to this embodiment, the positive electrode active material is particularly preferably an NMC composite oxide (high nickel NMC composite oxide) that satisfies the following conditions in the general formula (1): 0.8≦b≦0.9, 0<c≦0.2, 0<d≦0.2, and 0≦x≦0.2. A Ni atomic ratio b of 0.8 or more is preferable because it provides a better balance between capacity and life characteristics. Furthermore, a Ni atomic ratio b of 0.9 or less can reduce gas generation associated with the electrode reaction. Therefore, it is preferable because deterioration in cycle durability due to gas generation is less likely to occur. Furthermore, a high nickel atomic ratio can more significantly achieve the effects of the present invention. In this case, it is more preferable that c and d in the general formula (1) satisfy the following conditions: 0.05≦c≦0.2 and 0.03≦d≦0.2, from the viewpoint of improving the balance between capacity and life characteristics.

[0022] The average particle size of the positive electrode active material is not particularly limited, but from the viewpoint of achieving high output, it is preferably 1 to 100 μm, more preferably 1 to 20 μm. In this specification, the average particle size of the particles is the median diameter (D50) measured by a particle size distribution measuring device using a laser diffraction / scattering method.

[0023] The positive electrode active material layer further includes a solid electrolyte. By including the solid electrolyte in the positive electrode active material layer, the ionic conductivity of the positive electrode active material layer can be improved. Examples of the solid electrolyte include sulfide solid electrolytes and oxide solid electrolytes. In this specification, the solid electrolyte refers to a material mainly composed of an ion conductor capable of ion conduction in a solid, and in particular, a material having a lithium ion conductivity of 1×10 at room temperature (25° C.). －５ S / cm or more, and this lithium ion conductivity is preferably 1×10－４ The ionic conductivity is 200 S / cm or more. Here, the value of the ionic conductivity can be measured by an AC impedance method.

[0024] In this specification, the solid electrolyte contained in the positive electrode active material layer is referred to as the “first solid electrolyte,” and the solid electrolyte contained in the solid electrolyte layer described below is referred to as the “second solid electrolyte.” Therefore, the order of “first” and “second” itself has no meaning, and these terms are merely used to distinguish between the locations where the solid electrolytes are present.

[0025] The solid electrolyte (first solid electrolyte) contained in the positive electrode active material layer is not particularly limited, but is preferably a sulfide solid electrolyte containing an S element, from the viewpoint of exhibiting excellent lithium ion conductivity and being able to more closely follow volume changes of the electrode active material during charge and discharge. Furthermore, since the sulfide solid electrolyte easily reduces the positive electrode active material under reduced pressure, the effect of improving the rapid charging characteristics achieved by the method of the present invention can be more significantly achieved. The solid electrolyte contained in the positive electrode active material layer is more preferably a sulfide solid electrolyte containing Li, M, and S, where the M element contains at least one element selected from the group consisting of P, Si, Ge, Sn, Ti, Zr, Nb, Al, Sb, Br, Cl, and I, and even more preferably a sulfide solid electrolyte containing S, Li, and P.

[0026] The sulfide solid electrolyte is Li ３ P.S. ４ It may have a Li framework. ４ P ２ S ７ It may have a Li framework. ４ P ２ S ６ It may have a Li skeleton. ３ P.S. ４ Examples of sulfide solid electrolytes having a skeleton include LiI-Li ３ P.S. ４ , LiI-LiBr-Li ３ P.S. ４ , Li ３ P.S. ４ In addition, Li ４ P ２ S７ Examples of sulfide solid electrolytes having a skeleton include Li-P-S solid electrolytes called LPS. （４－ｘ） Ge （１－ｘ） P ｘ S ４ (x satisfies 0<x<1) or the like. More specifically, for example, LPS (Li ２ S-P ２ S ５ ), Li ７ P ３ S １１ , Li ３．２ P ０．９６ S., Li. ３．２５ Ge ０．２５ P ０．７５ S ４ , Li １０ GeP ２ S １２ , or Li ６ P.S. ５ X (wherein X is Cl, Br or I). ２ S-P ２ S ５ " is written by Li ２ S and P ２ S ５ The same applies to other descriptions. Among them, the sulfide solid electrolyte is preferably LPS (Li ２ S-P ２ S ５ ), Li ６ P.S. ５ X (wherein X is Cl, Br or I), Li ７ P ３ S １１ , Li ３．２ P ０．９６ S and Li ３ P.S. ４ is selected from the group consisting of:

[0027] Examples of the shape of the solid electrolyte include particulate shapes such as spherical shapes and oval spherical shapes, thin films, etc. When the solid electrolyte is particulate, its average particle size (D50) is not particularly limited, but is preferably 0.01 μm or more and 40 μm or less, more preferably 0.1 μm or more and 20 μm or less, and even more preferably 0.1 μm or more and 10 μm or less.

[0028] In a preferred embodiment of the present invention, the positive electrode active material layer contains a lithium-nickel composite oxide as the positive electrode active material and a sulfide solid electrolyte as the solid electrolyte. The present invention prevents a side reaction in which the positive electrode active material, which is an oxidizing agent, is reduced by the solid electrolyte, which is a reducing agent, in a reduced-pressure environment. The effects of the present invention can be obtained regardless of the type of positive electrode active material, but lithium-nickel composite oxide in particular is easily reduced by the sulfide solid electrolyte, and is therefore highly effective in improving capacity and rapid charging efficiency.

[0029] The positive electrode active material layer may further contain at least one of a conductive additive and a binder in addition to the above-described positive electrode active material and solid electrolyte.

[0030] Examples of conductive additives include metals such as aluminum, stainless steel (SUS), silver, gold, copper, and titanium, alloys or metal oxides containing these metals, carbon fibers (specifically, vapor-grown carbon fibers (VGCF), polyacrylonitrile-based carbon fibers, pitch-based carbon fibers, rayon-based carbon fibers, activated carbon fibers, etc.), carbon nanotubes (CNT), and carbon black (specifically, acetylene black, Ketjen Black (registered trademark), furnace black, channel black, thermal lamp black, etc.). Also, particulate ceramic materials or resin materials coated with the above-mentioned metal materials by plating or the like can also be used as conductive additives. Among these conductive additives, from the viewpoint of electrical stability, it is preferable to include at least one selected from the group consisting of aluminum, stainless steel, silver, gold, copper, titanium, and carbon, more preferably at least one selected from the group consisting of aluminum, stainless steel, silver, gold, and carbon, and even more preferably at least one carbon. These conductive additives may be used alone or in combination of two or more.

[0031] When the positive electrode active material layer contains a conductive additive, the content of the conductive additive in the positive electrode active material layer is not particularly limited, but is, for example, 1 to 10 mass %, more preferably 2 to 8 mass %. Within such a range, a stronger electron conduction path can be formed in the positive electrode active material layer, which can effectively contribute to improving the battery characteristics.

[0032] The binder used in the positive electrode active material layer is not particularly limited, and known binders can be used as appropriate. Examples of binders include polyvinylidene fluoride (PVDF), compounds in which the hydrogen atoms of PVDF are substituted with other halogen elements, polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC). The content of the binder in the positive electrode active material layer is not particularly limited, but is, for example, 0.1 to 10 mass%.

[0033] The thickness of the positive electrode active material layer varies depending on the configuration of the intended all-solid-state battery, but is preferably within the range of 0.1 to 1000 μm, more preferably 10 to 200 μm, and even more preferably 40 to 100 μm.

[0034] [Solid Electrolyte Layer] The solid electrolyte layer is interposed between the positive electrode active material layer and the negative electrode active material layer and contains a solid electrolyte (usually as a main component). There are no particular restrictions on the specific form of the solid electrolyte (second solid electrolyte) contained in the solid electrolyte layer, and the first solid electrolyte and its preferred forms exemplified in the section on the positive electrode active material layer can be similarly adopted. The solid electrolyte contained in the solid electrolyte layer may be the same as or different from the solid electrolyte contained in the positive electrode active material layer.

[0035] The solid electrolyte contained in the solid electrolyte layer is preferably a sulfide solid electrolyte. Because sulfide solid electrolytes are easily oxidized, the charge-discharge efficiency of all-solid-state batteries containing a sulfide solid electrolyte is likely to decrease when the battery is initially charged in an oxygen-containing atmosphere. Therefore, the effects of the present invention can be more significantly achieved.

[0036] Among these, LPS (Li ２ S-P ２ S ５ ), Li ６ P.S. ５ X (wherein X is Cl, Br or I), Li ７ P ３ S １１ , Li ３．２ P ０．９６ S and Li ３ P.S. ４ In some cases, a solid electrolyte other than the above-mentioned solid electrolytes may be used in combination.

[0037] The content of the solid electrolyte in the solid electrolyte layer is, for example, preferably in the range of 10 to 100 mass %, more preferably in the range of 50 to 100 mass %, and even more preferably in the range of 90 to 100 mass %, relative to the total mass of the solid electrolyte layer.

[0038] The solid electrolyte layer may further contain a binder in addition to the solid electrolyte. The binder is not particularly limited, and known binders can be used as appropriate. For example, the binders described above for the positive electrode active material layer can be similarly employed. The content of the binder in the solid electrolyte layer is not particularly limited, and is, for example, 1 to 10 mass %.

[0039] The solid electrolyte layer may be in a form in which a solid electrolyte is supported on a porous body. In this case, a binder may be further supported on the porous body. The material of the porous body is not particularly limited, and conventionally known knowledge may be appropriately referred to.

[0040] The thickness of the solid electrolyte layer varies depending on the intended configuration of the all-solid-state battery, but is preferably in the range of 0.1 to 1000 μm, and more preferably 10 to 100 μm.

[0041] [Negative Electrode Intermediate Layer] In the all-solid-state battery according to this embodiment, particularly in the case of a lithium deposition type all-solid-state battery, it is preferable to have a negative electrode intermediate layer adjacent to the surface of the solid electrolyte layer facing the negative electrode current collector. The negative electrode intermediate layer is not particularly limited, but preferably contains at least one selected from the group consisting of a metal material capable of alloying with lithium and a carbon material capable of absorbing lithium ions, and a binder. It is preferable that the negative electrode intermediate layer as a whole is conductive. The volume resistivity of the negative electrode intermediate layer is not particularly limited, but is preferably 10 ２ In this specification, the volume resistivity of the negative electrode intermediate layer is a value measured using an electrode resistance measurement system (manufactured by Hioki E.E. Corporation, product name: RM2610).

[0042] The negative electrode intermediate layer preferably contains at least one metal material selected from the group consisting of metal materials that can be alloyed with lithium. By including a metal material that can be alloyed with lithium in the negative electrode intermediate layer, lithium metal can be more uniformly deposited on the current collector surface. Specific examples of metal materials that can be alloyed with lithium include indium (In), aluminum (Al), silicon (Si), tin (Sn), magnesium (Mg), gold (Au), silver (Ag), zinc (Zn), and alloys containing at least one of these. Among these, the metal material preferably contains at least one selected from the group consisting of In, Al, Si, Sn, Mg, Au, Ag, and Zn, more preferably at least one selected from the group consisting of Ag, Mg, Zn, and Al, even more preferably at least one selected from the group consisting of Ag, Mg, and Zn, and particularly preferably Ag.

[0043] The negative electrode intermediate layer preferably contains at least one selected from the group consisting of carbon materials capable of absorbing lithium ions, instead of or in addition to containing at least one selected from the group consisting of metal materials capable of alloying with lithium. The inclusion of a carbon material capable of absorbing lithium ions in the negative electrode intermediate layer can suppress the precipitation and growth of lithium dendrites. Specific examples of carbon materials capable of absorbing lithium ions include carbon black (specifically, acetylene black, Ketjen Black (registered trademark), furnace black, channel black, thermal lamp black, etc.), carbon nanotubes (CNT), graphite, hard carbon, etc. Among these, the carbon material preferably contains at least one selected from the group consisting of carbon black, and more preferably contains at least one selected from the group consisting of acetylene black, Ketjen Black (registered trademark), furnace black, channel black, and thermal lamp black.

[0044] The negative electrode intermediate layer may further contain a metal material other than the metal material capable of alloying with lithium (a metal material that does not alloy with lithium) in addition to at least one selected from the group consisting of a metal material capable of alloying with lithium and a carbon material capable of absorbing lithium ions. Examples of metal materials that do not alloy with lithium include nickel (Ni) and copper (Cu). According to one embodiment, the negative electrode intermediate layer contains at least one selected from the group consisting of a carbon material capable of absorbing lithium ions and a metal material that does not alloy with lithium.

[0045] According to a preferred embodiment, the negative electrode intermediate layer includes at least one kind of metal particles containing the above-described metal material capable of alloying with lithium, and at least one kind of carbon particles containing the above-described carbon material capable of absorbing lithium ions. By using both the metal particles and the carbon particles to form the negative electrode intermediate layer, an all-solid-state battery with even better cycle characteristics can be obtained.

[0046] When both carbon particles and metal particles are used, the mass ratio of the carbon particles to the metal particles (carbon particles:metal particles) is preferably 10:1 to 1:1, more preferably 5:1 to 2:1, and even more preferably 4:1 to 2.5:1. The volume ratio of the carbon particles to the metal particles (carbon particles:metal particles) is preferably 99:1 to 70:30, and more preferably 95:5 to 75:25. When the compounding ratio (mass ratio or volume ratio) of the carbon particles to the metal particles is within the above range, an all-solid-state battery with even more excellent cycle characteristics can be obtained.

[0047] The negative electrode intermediate layer may further contain a binder. The type of binder is not particularly limited, and binders known in the art can be appropriately used. Examples of binders include polyvinylidene fluoride (PVDF), compounds in which hydrogen atoms of PVDF are substituted with other halogen elements, polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC). Among these, the binder preferably contains polyvinylidene fluoride (PVDF), and more preferably is polyvinylidene fluoride (PVDF).

[0048] The content of the binder in the negative electrode intermediate layer is, for example, 8% by mass or more and 20% by mass or less, preferably 10% by mass or more and 18% by mass or less, and more preferably 12% by mass or more and 16% by mass or less, relative to 100% by mass (the total of the masses of the metal material, the carbon material, and the binder). When the content of the binder is within the above range, the precipitation and growth of lithium dendrites can be further suppressed.

[0049] The thickness of the negative electrode intermediate layer is not particularly limited, but is preferably 1 to 20 μm, more preferably 2 to 15 μm, and even more preferably 5 to 15 μm. When the thickness of the negative electrode intermediate layer is within the above range, it is possible to simultaneously suppress the precipitation and growth of lithium dendrites and the decrease in energy density.

[0050] [Negative Electrode Active Material Layer] The negative electrode active material layer contains a negative electrode active material. The type of negative electrode active material is not particularly limited, but includes carbon materials, metal oxides, and metal active materials. Furthermore, a lithium-containing metal may be used as the negative electrode active material. Such a negative electrode active material is not particularly limited as long as it is a lithium-containing active material, and examples thereof include lithium metal and lithium-containing alloys. Examples of lithium-containing alloys include alloys of Li with at least one of In, Al, Si, Sn, Mg, Au, Ag, and Zn. The negative electrode active material preferably contains lithium metal or a lithium-containing alloy, and particularly preferably contains lithium metal. Because lithium metal is easily oxidized, initial charging in an oxygen-containing atmosphere can easily cause deactivation due to oxidation of the lithium metal negative electrode active material, which can lead to a decrease in charge / discharge efficiency. Therefore, the effect of improving battery capacity can be more pronounced. Furthermore, when the negative electrode active material is lithium metal, it is particularly susceptible to pressure distribution, and therefore, performing a depressurization process can more effectively suppress short circuits, resulting in greater performance improvements.

[0051] The negative electrode active material layer may further contain a solid electrolyte as needed. There are no particular restrictions on the specific form of the solid electrolyte contained in the negative electrode active material layer, and the solid electrolytes and their preferred forms exemplified in the section on the positive electrode active material layer may be similarly employed. The content of the solid electrolyte in the negative electrode active material layer is, for example, preferably in the range of 1 to 60 mass %, more preferably in the range of 10 to 50 mass %.

[0052] The negative electrode active material layer may further contain at least one of a binder and a conductive additive in addition to the above-described negative electrode active material and solid electrolyte. The thickness of the negative electrode active material layer varies depending on the configuration of the intended all-solid-state battery, but is preferably in the range of 0.1 to 1000 μm, more preferably 40 to 100 μm.

[0053] When lithium metal or a lithium-containing alloy is used as the negative electrode active material, the all-solid-state battery according to this embodiment may be a so-called lithium deposition type battery in which lithium metal as the negative electrode active material is deposited on the negative electrode current collector during the charging process. Therefore, in this embodiment, the thickness of the negative electrode active material layer increases as the charging process progresses, and decreases as the discharging process progresses. The negative electrode active material layer may not be present during full discharge, but in some cases, a negative electrode active material layer composed of a certain amount of lithium metal may be present during full discharge. The thickness of the negative electrode active material layer (lithium metal layer) during full charge is not particularly limited, but is typically 0.1 to 1000 μm.

[0054] <Method for Manufacturing an All-Solid-State Battery> A method for manufacturing an all-solid-state battery according to one embodiment of the present invention is a method for manufacturing an all-solid-state battery in which a power generating element including a positive electrode having a positive electrode active material layer containing a positive electrode active material and a first solid electrolyte, a negative electrode having a negative electrode active material layer containing a negative electrode active material, and a solid electrolyte layer interposed between the positive electrode and the negative electrode and containing a second solid electrolyte is sealed inside a battery outer casing, the method comprising: a chemical formation step including a step of initially charging the power generating element under an inert gas atmosphere; and a step of, after the chemical formation step, sealing the power generating element inside the battery outer casing under reduced pressure. According to this manufacturing method, an all-solid-state battery having both excellent capacity and rapid charging characteristics can be obtained. Each step in this manufacturing method is described below.

[0055] [Chemical Conversion Step (Chemical Conversion Treatment Step)] The chemical conversion step includes a step of initially charging a power generating element having a positive electrode, a solid electrolyte layer, and a negative electrode in an inert gas atmosphere.

[0056] The specific forms of the positive electrode, solid electrolyte layer, and negative electrode are as described above. The methods for producing the positive electrode, solid electrolyte layer, and negative electrode, and the method for laminating them to produce a power-generating element are not particularly limited. The steps of producing the positive electrode, solid electrolyte layer, and negative electrode and laminating them to produce a power-generating element are preferably carried out in an inert gas atmosphere.

[0057] Examples of inert gases include nitrogen and rare gases (helium, argon, xenon, neon), with argon being preferred. The inert gas may contain impurities, but from the viewpoint of preventing adverse effects on the performance of the all-solid-state battery, the impurity content is less than 0.1% by volume, preferably less than 0.01% by volume, and more preferably less than 0.001% by volume. Examples of impurities include moisture, oxygen, nitrogen, and solvents. In the method of this embodiment, an inert gas atmosphere refers to an environment filled with an inert gas having a total impurity content of less than 0.1% by volume. In the method of this embodiment, the inert gas atmosphere is not particularly limited, but is preferably an inert gas atmosphere with a dew point of −60° C. or lower, and more preferably an inert gas atmosphere with a dew point of −68° C. or lower.

[0058] The initial charge refers to the first charge of a power generating element having a positive electrode, a solid electrolyte layer, and a negative electrode. The initial charge may be performed, for example, by constant current charge, constant voltage charge, or constant current / constant voltage charge. The current density during the initial charge is not particularly limited, and may be, for example, 0.1 to 5 mA / cm. ２ and preferably 0.5 to 2 mA / cm ２ Within the above range, modification (structural change) of the surfaces of the particles of the positive electrode active material proceeds effectively, and rapid charge / discharge characteristics can be further improved.

[0059] The upper limit voltage (end-of-charge voltage) of the initial charge is not particularly limited and can be adjusted appropriately depending on the types of positive electrode active material and negative electrode active material used, but is, for example, 3.6 to 4.3 V, preferably 3.6 to 4.2 V. If the upper limit voltage is 3.6 V or higher, surface modification (structural change) of the particles of the positive electrode active material is more likely to proceed, thereby further improving rapid charge / discharge characteristics. Furthermore, if the upper limit voltage is 4.3 V or lower, particularly 4.2 V or lower, excessive oxygen desorption from the positive electrode active material and oxidation of the solid electrolyte can be suppressed. Therefore, in addition to excellent rapid charge characteristics, a higher capacity can be obtained.

[0060] In a preferred embodiment, the initial charge includes constant-voltage charging. For example, the initial charge includes constant-voltage charging or constant-current / constant-voltage charging. By including constant-voltage charging or constant-current / constant-voltage charging in the initial charge, the power generating element can be held at a constant voltage for a certain period of time, thereby sufficiently modifying the surface of the positive electrode active material particles. As a result, rapid charge characteristics can be further improved. Furthermore, the holding time at the upper limit voltage during constant-voltage charging or constant-current / constant-voltage charging is not particularly limited, but is, for example, 0.5 to 48 hours, preferably 1 to 36 hours. When the holding time at the upper limit voltage is within the above range, the surface modification of the positive electrode active material particles due to the chemical conversion process can be further advanced, thereby further improving rapid charge / discharge characteristics. In a preferred embodiment, the initial charge is performed by constant-current charging up to the desired upper limit voltage, followed by constant-voltage charging. In this case, the preferred forms of constant-current charging and constant-voltage charging are the same as those described above.

[0061] The temperature conditions during the initial charge are not particularly limited, and are, for example, 20 to 80°C, preferably 50 to 70°C.

[0062] In the power generating element after the initial charge in an inert gas atmosphere, the surface of the particles of the positive electrode active material is modified, forming a stable structurally changed layer on the surface of the particles of the positive electrode active material, making the positive electrode active material less susceptible to deterioration. Therefore, after the initial charge, the power generating element may be discharged, may be repeatedly charged and discharged, or may be left standing after charging or discharging before the reduced pressure sealing described below. Furthermore, the power generating element after the initial charge in an inert gas atmosphere may be held in an atmosphere other than the inert gas atmosphere, such as under reduced pressure, or may be further charged and discharged in an atmosphere other than the inert gas atmosphere. Preferably, all steps from the initial charge to the reduced pressure sealing described below are performed in the inert gas atmosphere used for the initial charge.

[0063] The chemical conversion step preferably further includes a step of discharging the power generating element after the initial charge. The effects of the chemical conversion treatment are realized only by the initial charge. However, because the positive and negative electrode active materials in the charged state have high oxidizing and reducing powers, they may undergo side reactions with trace amounts of atmospheric impurities (e.g., moisture, nitrogen) during the subsequent sealing process. Therefore, by discharging the power generating element after charging and then sealing it, side reactions can be suppressed. As a result, the battery capacity and rapid charging characteristics can be further improved.

[0064] The discharge step is preferably carried out in an inert gas atmosphere. The temperature conditions during discharge are not particularly limited, and are, for example, 20 to 80°C, and preferably 50 to 70°C.

[0065] The current density during discharge is not particularly limited, but is, for example, 0.1 to 10 mA / cm ２ and preferably 1 to 5 mA / cm ２ It is preferable to perform constant current discharge at the above current density. The discharge cut-off voltage is not particularly limited, but is, for example, 2.8 to 3.2 V.

[0066] [Decompression Sealing Step] In the reduction pressure sealing step, after the chemical conversion step, the power generating element is sealed in the battery outer casing under reduced pressure.

[0067] As the battery exterior, for example, a bag-shaped case using an aluminum-containing laminate film 29 that can cover the power generating element as shown in FIG. 1 can be preferably used. The laminate film can be, for example, a three-layer laminate film formed by laminating PP, aluminum, and nylon in this order, but is not limited thereto. A laminate film is desirable from the viewpoint of its high output and excellent cooling performance, making it suitable for use in batteries for large devices such as EVs and HEVs. Furthermore, it is more preferable that the battery exterior be an aluminum-containing laminate film, since this allows for easy adjustment of the collective pressure applied to the power generating element from the outside.

[0068] The method for vacuum-sealing the power generating element inside the battery exterior is not particularly limited. For example, when the battery exterior is a bag-shaped laminate film, the power generating element is housed inside the laminate film, and the inside of the laminate film is decompressed using a known decompression device. Then, the edges of the laminate film are sealed by heat fusion or the like. The degree of vacuum inside the battery exterior during decompression is also not particularly limited, and conventionally known knowledge can be appropriately adopted. The degree of vacuum is preferably 11.3 kPa or less, more preferably 6.3 kPa or less, even more preferably 2 kPa or less, and particularly preferably 1.3 kPa or less. The temperature conditions during vacuum sealing are also not particularly limited, and are, for example, 20 to 80°C.

[0069] One embodiment of the method for manufacturing an all-solid-state battery of the present invention has been described above. However, the present invention is not limited to the configurations described in the above-described embodiment, and can be modified as appropriate based on the claims.

[0070] For example, the type of battery to which the all-solid-state battery according to the present invention is applied also includes a bipolar battery including a bipolar electrode having a positive electrode active material layer electrically coupled to one surface of a current collector and a negative electrode active material layer electrically coupled to the opposite surface of the current collector.

[0071] Furthermore, the secondary battery according to the present embodiment does not have to be an all-solid-state type. That is, the solid electrolyte layer may further contain a conventionally known liquid electrolyte (electrolytic solution). There is no particular limitation on the amount of liquid electrolyte (electrolytic solution) that can be contained in the solid electrolyte layer, but it is preferably an amount that allows the shape of the solid electrolyte layer formed by the solid electrolyte to be maintained and prevents leakage of the liquid electrolyte (electrolytic solution).

[0072] The following embodiments are also included within the scope of the present invention: a method for manufacturing an all-solid-state battery according to claim 1 having the features of claim 2; a method for manufacturing an all-solid-state battery according to claim 1 or 2 having the features of claim 3; a method for manufacturing an all-solid-state battery according to any one of claims 1 to 3 having the features of claim 4; a method for manufacturing an all-solid-state battery according to any one of claims 1 to 4 having the features of claim 5; and a method for manufacturing an all-solid-state battery according to any one of claims 1 to 5 having the features of claim 6.

[0073] The present invention will be described in more detail below with reference to examples. However, the technical scope of the present invention is not limited to the following examples. In the following examples and comparative examples, the inside of a glove box with an argon atmosphere having a dew point of -68°C or less is an environment filled with argon gas containing less than 0.001% by volume of total impurities. In addition, the instruments and devices used in the glove box were thoroughly dried in advance.

[0074] <Examples of Preparation of Evaluation Cell> [Example 1] (Preparation of Positive Electrode Active Material Layer) As a constituent material of the positive electrode active material layer, NMC composite oxide (LiNi ０．８ Mn ０．１ Co ０．１ O ２ ) and a solid electrolyte, an argyrodite-type sulfide solid electrolyte (Li ６ P.S. ５ Cl), acetylene black as a conductive additive, and styrene-butadiene rubber (SBR) as a binder were prepared.

[0075] In a glove box with an argon atmosphere having a dew point of −68° C. or less, a positive electrode active material, a solid electrolyte, a conductive additive, and a binder were weighed out to a mass ratio of 72:24:3:1 and dispersed in xylene to prepare a positive electrode active material slurry. Next, the positive electrode active material slurry prepared above was applied to both sides of a carbon-coated aluminum foil serving as a positive electrode current collector and dried to form a positive electrode active material layer (100 μm thick on each side), thereby producing a positive electrode.

[0076] (Preparation of Solid Electrolyte Layer) In a glove box with an argon atmosphere having a dew point of −68° C. or less, an argyrodite-type sulfide solid electrolyte (Li ６ P.S. ５ A solid electrolyte slurry was prepared by weighing out a 97:3 mass ratio of styrene-butadiene rubber (SBR) as a binder and dispersing the mixture in xylene. The resulting solid electrolyte slurry was applied to a 40 μm-thick porous body and dried to prepare a 40 μm-thick solid electrolyte layer supported on the porous body.

[0077] (Preparation of Negative Electrode Intermediate Layer) In a glove box with an argon atmosphere having a dew point of −68° C. or less, acetylene black (AB), silver (Ag) nanoparticles, and polyvinylidene fluoride (PVDF) as a binder were weighed out to a mass ratio of 65:21:14 and dispersed in N-methylpyrrolidone to prepare a negative electrode intermediate layer slurry. The obtained negative electrode intermediate layer slurry was applied to both sides of a stainless steel foil as a negative electrode current collector and dried to obtain a negative electrode intermediate layer (10 μm thick on each side).

[0078] (Preparation of Laminate of Positive Electrode, Solid Electrolyte Layer, Negative Electrode Intermediate Layer, and Negative Electrode Current Collector) In a glove box in an argon atmosphere with a dew point of −68° C. or less, the solid electrolyte layer and negative electrode intermediate layer prepared above were placed in this order on both sides of the positive electrode prepared above, and the resulting mixture was roll-pressed to obtain a laminate in which the positive electrode active material layer, solid electrolyte layer, negative electrode intermediate layer, and negative electrode current collector were laminated in this order on both sides of the positive electrode current collector.

[0079] (Preparation of Laminated Cell) In a glove box with an argon atmosphere having a dew point of −68° C. or less, an aluminum positive electrode tab and a nickel-plated copper negative electrode tab were joined to the carbon-coated aluminum foil (positive electrode current collector) and stainless steel foil (negative electrode current collector) of the laminate prepared above, respectively, using an ultrasonic welder. This was placed inside an aluminum laminate film, and the opening of the laminate film was hermetically sealed by heat welding to obtain a laminated cell. The interior of the laminated cell prepared in this way was filled with argon gas containing less than 0.001% by volume of total impurities.

[0080] (Chemical Conversion Treatment) The chemical conversion treatment was carried out by applying a restraining pressure of 3 MPa in the lamination direction of the laminate cell produced above using a pressure member. The chemical conversion treatment was carried out using a charge / discharge tester (HJ-SD8, manufactured by Hokuto Denko Corporation) in a constant temperature bath set at 60°C. The laminate cell was placed in the bath, and after the cell temperature became constant, a chemical conversion step was carried out using a current of 1.0 mA / cm ２ The battery was charged at a constant current density of 2.0 mA / cm up to a cell voltage of 4.3 V. ２ The battery was discharged at a constant current density of 1000 kJ / s until the cell voltage reached 3.0 V.

[0081] (Decompressed Sealing) In a glove box filled with an argon atmosphere having a dew point of −68° C. or less, an opening was formed by cutting the laminate edge of the laminate cell that had undergone the chemical conversion treatment, and the inside of the laminate film was reduced in pressure to 1.3 kPa using a vacuum packaging machine (TOSPACK, manufactured by TOSEI Corporation), and the laminate was hermetically sealed at 25° C. to obtain an evaluation cell that was a lithium deposition-type all-solid-state battery of this example.

[0082] Example 2 An evaluation cell for this example was produced in the same manner as in Example 1, except that the charge cut-off voltage (upper limit voltage) of constant current charging was changed to 4.2 V in the chemical conversion treatment.

[0083] [Example 3] An evaluation cell for this example was produced in the same manner as in Example 1, except that the chemical conversion treatment was carried out as follows: (Chemical conversion treatment) The chemical conversion treatment was carried out while applying a restraining pressure of 3 MPa in the stacking direction of the laminate cell produced above. The chemical conversion treatment was carried out using a charge-discharge tester (HJ-SD8, manufactured by Hokuto Denko Corporation) in a constant temperature bath set at 60°C. The laminate cell was placed in the bath, and after the cell temperature became constant, a current of 1.0 mA / cm was applied as the chemical conversion step. ２ The cell was charged at a constant current density of 2.0 mA / cm up to a cell voltage of 4.2 V, followed by charging at a constant voltage of 4.2 V for 24 hours. ２ The battery was discharged at a constant current density of 1000 kJ / s until the cell voltage reached 3.0 V.

[0084] Example 4 An evaluation cell for this example was produced in the same manner as in Example 1, except that the charge cut-off voltage (upper limit voltage) of constant current charging was changed to 3.6 V in the chemical conversion treatment.

[0085] [Comparative Example 1] A positive electrode active material layer, a solid electrolyte layer, and a negative electrode intermediate layer were prepared in the same manner as in Example 1, and a laminate of a positive electrode, a solid electrolyte layer, a negative electrode intermediate layer, and a negative electrode current collector was obtained. In the preparation of the laminate cell of Example 1, the laminate was placed inside an aluminum laminate film, and then the inside of the laminate film was reduced in pressure to 1.3 kPa using a vacuum packaging machine (TOSPACK, TOSEI Corporation) and hermetically sealed at 25°C. The laminate cell thus obtained was subjected to the same chemical conversion treatment as in Example 1, and an evaluation cell for this comparative example was prepared.

[0086] Comparative Example 2 An evaluation cell for this comparative example was produced in the same manner as in Example 1, except that the vacuum sealing was not carried out.

[0087] [Comparative Example 3] In Example 1, the assembly in which the positive electrode tab and the negative electrode tab were joined was sealed in a laminate film under atmospheric pressure (in an atmosphere containing 20% ​​by volume of oxygen) to produce a laminate cell. Next, the above-mentioned chemical conversion treatment was performed while applying a restraining pressure of 3 MPa in the stacking direction of the laminate cell using a pressure member. Thereafter, in a glove box in an argon atmosphere with a dew point of -68 ° C or less, the laminate end of the laminate cell that had undergone the chemical conversion treatment was cut to form an opening, and the inside of the laminate film was hermetically sealed at 25 ° C under a reduced pressure of 1.3 kPa using a vacuum packaging machine (TOSPACK, manufactured by TOSEI Corporation), to obtain an evaluation cell for this comparative example.

[0088] <Evaluation of Charge / Discharge Characteristics of All-Solid-State Battery> The charge / discharge characteristics of the evaluation cell prepared above were evaluated under the following conditions. The battery charge / discharge characteristics were evaluated using a charge / discharge tester (HJ-SD8, manufactured by Hokuto Denko Corporation) in a constant temperature bath set to 60°C while applying a restraining pressure of 3 MPa in the stacking direction of the laminate cell using a pressure member. The battery was placed in the bath, and after the cell temperature became constant, a current of 2.0 mA / cm was applied. ２ The battery was charged at a constant current density of 2.0 mA / cm until the cell voltage reached 4.3 V. ２ The battery was discharged at a constant current density of 0.05 V down to a cell voltage of 3.0 V. This charge-discharge cycle was repeated five times, and the capacity per mass of active material (mAh / g) was calculated from the discharge capacity value obtained and the mass value of the active material contained in the positive electrode, and this was taken as the rated capacity of the battery. The results are shown in Table 1 below. A rating of ◯ or △ indicates that the battery can be used without any problems according to the following evaluation criteria: ◯: 190 mAh / g or more; △: 160 mAh / g or more but less than 190 mAh / g; ×: less than 160 mAh / g.

[0089] <Evaluation of rapid charging characteristics of all-solid-state battery> Of the evaluation cells prepared above, those with a rated capacity of 160 mAh / g or more were subjected to rapid charging characteristics evaluation under the following conditions. The rapid charging characteristics evaluation of the battery was carried out using a charge / discharge tester (HJ-SD8, manufactured by Hokuto Denko Corporation) in a constant temperature bath set at 60°C while applying a restraining pressure of 3 MPa in the stacking direction of the laminate cell using a pressure member. The battery was placed in the bath, and after the cell temperature became constant, a current of 2.0 mA / cm was applied.２ The battery was then charged at a constant current density of 2.0 mA / cm (equivalent to 0.1 C) up to a cell voltage of 4.3 V, and the slow charge capacity was determined. ２ After constant current discharge at a current density of 20.0 mA / cm ２ The cells were charged at a constant current density (equivalent to 1 C) up to a cell voltage of 4.3 V, and this was taken as the fast charge capacity. The ratio (percentage) of the fast charge capacity to the slow charge capacity was taken as the fast charge characteristic (%). The results are shown in Table 1 below. According to the following evaluation criteria, if a rating is ◯, the cell can be used without any problems: ◯: Fast charge characteristic is 70% or more, △: Fast charge characteristic is less than 70%, ×: Short circuit occurred during fast charge.

[0090]

[0091] The results shown in Table 1 show that, as in Examples 1 to 4, the method of the present invention can produce all-solid-state batteries with excellent rated capacity and rapid charging characteristics. On the other hand, the cell of Comparative Example 3, in which the chemical formation process was performed under atmospheric pressure, did not achieve a sufficient rated capacity. Furthermore, the cell of Comparative Example 1, in which the chemical formation process was performed under reduced pressure, achieved a sufficient rated capacity but had poor rapid charging characteristics. The cell of Comparative Example 2, in which reduced pressure sealing was not performed, experienced a short circuit during rapid charging.

[0092] REFERENCE SIGNS LIST 10a laminated secondary battery, 11' negative electrode current collector, 11" positive electrode current collector, 13 negative electrode active material layer, 14 negative electrode intermediate layer, 15 positive electrode active material layer, 17 solid electrolyte layer, 19 single cell layer, 21 power generating element, 25 negative electrode current collector, 27 positive electrode current collector, 29 laminate film.

Claims

1. A method for producing an all-solid-state battery in which a power generating element including: a positive electrode having a positive electrode active material layer including a positive electrode active material and a first solid electrolyte; a negative electrode having a negative electrode active material layer including a negative electrode active material; and a solid electrolyte layer interposed between the positive electrode and the negative electrode and including a second solid electrolyte is sealed inside a battery exterior body, the method comprising: a chemical formation step including a step of initially charging the power generating element under an inert gas atmosphere; and a step of reducing the pressure and sealing the power generating element inside the battery exterior body after the chemical formation step.

2. The method for producing an all-solid-state battery according to claim 1, wherein the initial charging includes constant voltage charging.

3. The method for producing an all-solid-state battery according to claim 1 or 2, further comprising a step of discharging the power generating element after the initial charging in the chemical formation step.

4. The method for producing an all-solid-state battery according to claim 1 or 2, wherein the positive electrode active material is a lithium nickel composite oxide, and the first solid electrolyte is a sulfide solid electrolyte.

5. The method for producing an all-solid-state battery according to claim 1 or 2, wherein the negative electrode active material contains lithium metal.

6. The method for producing an all-solid-state battery according to claim 1 or 2, wherein an end-of-charge voltage of the initial charge is 3.6 to 4.2 V.

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