All-solid-state battery

Abstract

The purpose of the present invention is to provide a means capable of improving the cycle characteristics of an all-solid-state battery. Provided is an all-solid-state battery comprising a power generation element having a positive electrode that has a positive electrode active material layer containing a positive electrode active material and a first binder, a negative electrode, and a solid electrolyte layer that is interposed between the positive electrode and the negative electrode and contains a solid electrolyte and a second binder, wherein: the first binder and the second binder are different from each other; the all-solid-state battery furthermore has an adhesive layer adjacent to each of the main surface of the positive electrode active material layer facing the solid electrolyte layer and the main surface of the solid electrolyte layer facing the positive electrode active material layer; and the adhesive layer contains a solid electrolyte, the first binder, and the second binder.

Description

All solid state battery

[0001] The present invention relates to 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 configuration in which a positive electrode, a solid electrolyte layer containing a solid electrolyte, and a negative electrode are stacked in this order. Here, the solid electrolyte layer has the function of suppressing short circuits due to electrical contact between the positive electrode and the negative electrode. On the other hand, in order to increase the capacity of the battery, it is preferable that the thickness of the solid electrolyte layer is as thin as possible.

[0004] WO 2013 / 084944 discloses a technology for achieving both high reliability and improved capacity, in which the solid electrolyte layers adjacent to the first and second electrodes are laminated with specific first and second solid electrolyte layers. According to WO 2013 / 084944, the above-mentioned problem can be solved by making the content of organic compounds (e.g., binders) in the first solid electrolyte layer smaller than the content of organic compounds in the second solid electrolyte layer and by making the thickness of the first solid electrolyte layer smaller than the thickness of the second solid electrolyte layer.

[0005] However, according to the investigations of the present inventors, it has been found that in all-solid-state batteries employing the technology described in WO 2013 / 084944, sufficient cycle characteristics may not be obtained in some cases.

[0006] Therefore, an object of the present invention is to provide a means for improving the cycle characteristics of an all-solid-state battery.

[0007] 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 providing an adhesive layer between a positive electrode active material layer and a solid electrolyte layer so as to be in contact with these layers, and by having the adhesive layer contain both the binder contained in the positive electrode active material layer and the binder contained in the solid electrolyte layer, thereby completing the present invention.

[0008] That is, one aspect of the present invention relates to an all-solid-state battery including a power generating element including a positive electrode having a positive electrode active material layer containing a positive electrode active material and a first binder, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode and containing a solid electrolyte and a second binder, wherein the first binder and the second binder are different from each other, and the battery further includes adhesive layers adjacent to a main surface of the positive electrode active material layer facing the solid electrolyte layer and a main surface of the solid electrolyte layer facing the positive electrode active material layer, respectively, and the adhesive layers contain the solid electrolyte, the first binder, and the second binder.

[0009] 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.

[0010] One aspect of the present invention is an all-solid-state battery including a power generating element including a positive electrode having a positive electrode active material layer containing a positive electrode active material and a first binder, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode and containing a solid electrolyte and a second binder, wherein the first binder and the second binder are different from each other, and the all-solid-state battery further includes adhesive layers adjacent to a main surface of the positive electrode active material layer facing the solid electrolyte layer and a main surface of the solid electrolyte layer facing the positive electrode active material layer, respectively, the adhesive layers containing the solid electrolyte, the first binder, and the second binder. The all-solid-state battery according to this aspect can have improved cycle characteristics.

[0011] 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.

[0012] 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 the stacked-type secondary battery during charging. The stacked-type secondary battery 10a shown in FIG. 1 has a structure in which a substantially rectangular power-generating element 21, where charge and discharge reactions actually proceed, is sealed inside a laminate film 29, which is a battery exterior. 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 so as to contact the negative electrode active material layer 13 and the solid electrolyte layer 17, respectively. 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". An adhesive layer 16 is disposed so as to be in contact with the positive electrode active material layer 15 and the solid electrolyte layer 17, respectively. As a result, the negative electrode current collector 11', the negative electrode active material layer 13, the negative electrode intermediate layer 14, the solid electrolyte layer 17, the adhesive layer 16, the positive electrode active material layer 15, and the positive electrode current collector 11" constitute one unit cell layer 19. Therefore, it can be said that the stacked secondary battery 10a shown in FIG. 1 has a structure in which a plurality of unit cell layers 19 are stacked 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 and positive electrodes) are attached to the negative electrode current collector 11′ and the positive electrode current collector 11″, respectively, and are configured to be sandwiched between the ends of the laminate film 29 and extend to the outside of the laminate film 29. A restraining 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.

[0013] The main components of the all-solid-state battery according to this embodiment will be described below.

[0014] [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.

[0015] [Positive Electrode Active Material Layer] The positive electrode active material layer essentially contains a positive electrode active material and a first binder, and may contain a solid electrolyte and a conductive additive as needed.

[0016] 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. 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 other than those mentioned above include Si-containing active materials such as Li ４ Ti ５ O １２ Among these, composite oxides containing lithium and nickel are preferably used, and Li(Ni—Mn—Co)O is more preferably used. ２Also, those in which some of these transition metals have been replaced with other elements (hereinafter also simply referred to as "NMC composite oxides") are 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, and high capacity can be achieved.

[0017] 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.

[0018] 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 greater 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 electrode reactions. Therefore, it is preferable because it is less likely to cause a decrease in cycle durability due to gas generation. Furthermore, because high-nickel NMC composite oxides have a high capacity, they undergo large volume changes due to contraction and expansion associated with charge-discharge reactions. This makes them prone to peeling between the positive electrode active material layer and the solid electrolyte layer due to repeated charge-discharge cycles. In the all-solid-state battery according to this embodiment, by disposing an adhesive layer in contact with both the positive electrode active material layer and the solid electrolyte layer, the adhesion between the positive electrode active material layer and the solid electrolyte layer via the adhesive layer can be improved. This can suppress peeling between the positive electrode active material layer and the solid electrolyte layer even after repeated charge and discharge. As a result, it is possible to further improve the cycle characteristics of the all-solid-state battery. Therefore, when the positive electrode active material contains a high-nickel NMC composite oxide (or the positive electrode active material is a high-nickel NMC composite oxide), the effects of the present invention can be more significantly obtained. In this case, in general formula (1), it is more preferable that c and d are 0.05≦c≦0.2 and 0.03≦d≦0.2, from the viewpoint of improving the balance between capacity and life characteristics.

[0019] 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.

[0020] The first binder is not particularly limited as long as it is different from the second binder contained in the solid electrolyte layer described above. In particular, from the viewpoint of improving the electronic conductivity and ionic conductivity of the positive electrode active material layer, the first binder is preferably a fibrous binder. In this specification, the term "fibrous binder" refers to a binder composed of fibers having an aspect ratio of 10 or more and a minimum Feret diameter of 0.2 μm or less in an observation image obtained by observing a cross section of a layer containing the binder using a scanning electron microscope (SEM). The aspect ratio is calculated by dividing the maximum Feret diameter by the minimum Feret diameter. The maximum Feret diameter is the maximum distance between two parallel lines when the outline of the binder is sandwiched between the lines, and the minimum Feret diameter is the minimum distance between the lines when the outline of the binder is sandwiched between the lines. In this specification, the term "cross section of a layer" refers to a cross section of the layer cut in the stacking direction in an all-solid-state battery (i.e., a cross section of the layer cut in the thickness direction). As such a fibrous binder, a binder that can be fibrillated by applying shear force can be suitably used. Preferred types of such fibrillated binders include polytetrafluoroethylene (PTFE), carboxymethyl cellulose, polyethylene oxide, polyvinyl alcohol, and polyethylene, with polytetrafluoroethylene (PTFE) being more preferred. The use of such a binder further improves both the binding properties and the maintenance of electron conduction paths and / or lithium ion conduction paths between particles. The polytetrafluoroethylene may include those in which a portion of the terminal or side chain is substituted (modified) with another substituent. In the case where a portion of the terminal or side chain is substituted (modified) with another substituent, the proportion of the structural units in which the terminal or side chain is substituted (modified) with another substituent relative to 100 mol% of all structural units is preferably 10 mol% or less, more preferably 5 mol% or less.

[0021] The content of the first binder in the positive electrode active material layer is not particularly limited, but is preferably in the range of 1 to 10 mass %, more preferably in the range of 1 to 5 mass %, and even more preferably 1 mass % or more and 2.5 mass % or less, relative to 100 mass % of the total solid content in the positive electrode active material layer. By having the content of the first binder in the above range, the strength of the positive electrode active material layer can be further increased, and the ionic conductivity and electronic conductivity of the positive electrode active material layer can also be improved.

[0022] The positive electrode active material layer may further include a solid electrolyte. By including a 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 term "solid electrolyte" refers to a material mainly composed of an ion conductor capable of ion conduction in a solid state, 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.

[0023] From the viewpoint of exhibiting excellent lithium ion conductivity and being able to better follow the volume change of the electrode active material that accompanies charge and discharge, the solid electrolyte is preferably a sulfide solid electrolyte containing an S element, more preferably a sulfide solid electrolyte containing a Li element, an M element, and an S element, wherein 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 an S element, a Li element, and a P element.

[0024] 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. ３P.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 S ７ 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 P３ S １１ , Li ３．２ P ０．９６ S and Li ３ P.S. ４ is selected from the group consisting of:

[0025] 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.

[0026] The positive electrode active material layer may further contain a conductive additive in addition to the above-described positive electrode active material and solid electrolyte.

[0027] 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 nanofibers (CNF), carbon nanotubes (CNT), and carbon black (specifically, acetylene black, Ketjen Black (registered trademark), furnace black, channel black, thermal lamp black, etc.). These examples are not limited to these. Furthermore, 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. It is more preferable to include at least one selected from the group consisting of aluminum, stainless steel, silver, gold, and carbon, and it is even more preferable to include at least one carbon. These conductive additives may be used alone or in combination of two or more.

[0028] 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 preferably 0 to 10 mass %, more preferably 1 to 8 mass %, and even more preferably 2 to 7 mass %, relative to the total mass of the positive electrode active material layer (total solid content 100 mass %). Within such a range, it is possible to form a stronger electron conduction path in the positive electrode active material layer, which can effectively contribute to improving battery characteristics.

[0029] The thickness of the positive electrode active material layer varies depending on the intended configuration of the all-solid-state battery, but is preferably within the range of 0.1 to 1000 μm, and more preferably 40 to 100 μm.

[0030] [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 limitations on the specific form of the solid electrolyte contained in the solid electrolyte layer, and the solid electrolytes exemplified in the section on the positive electrode active material layer and their preferred forms can be similarly adopted. Among them, from the viewpoint of high ionic conductivity, 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.

[0031] The content of the solid electrolyte in the solid electrolyte layer is, for example, preferably in the range of 10 mass % or more and less than 100 mass %, more preferably in the range of 50 mass % or more and 99 mass % or less, and even more preferably in the range of 90 mass % or more and 97 mass % or less, relative to the total mass of the solid electrolyte layer.

[0032] The solid electrolyte layer further contains a second binder in addition to the solid electrolyte described above. The second binder is not particularly limited as long as it is different from the first binder contained in the positive electrode active material layer described above. In particular, from the viewpoint of increasing the strength of the solid electrolyte layer and suppressing dendrite elongation, the second binder is preferably a non-fibrous binder. In this specification, "non-fibrous binder" refers to a binder other than the above-mentioned "fibrous binder." That is, in this specification, "non-fibrous binder" refers to a binder having an aspect ratio of less than 10 or a minimum Feret diameter of greater than 0.2 μm in an image obtained by observing a cross section of a layer containing the binder using a scanning electron microscope (SEM). Types of binders that can have such a non-fibrous shape include styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), ethyl cellulose, and acrylic resin, and styrene-butadiene rubber (SBR) is more preferred. By using such a binder with high binding properties, the strength of the solid electrolyte layer can be further improved.

[0033] The content of the second binder in the solid electrolyte layer is not particularly limited, but is preferably in the range of 1 to 15 mass %, more preferably in the range of 3 to 10 mass %, and even more preferably more than 4 mass % to 7 mass % or less, relative to 100 mass % of the total solid content in the solid electrolyte layer. By having the content of the second binder in the above range, the strength of the solid electrolyte layer can be further increased and the elongation of dendrites can be suppressed.

[0034] 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, more preferably 10 to 40 μm.

[0035] The all-solid-state battery according to the present embodiment further includes adhesive layers adjacent to a main surface of the cathode active material layer facing the solid electrolyte layer and a main surface of the solid electrolyte layer facing the cathode active material layer, the adhesive layers essentially containing a solid electrolyte, the first binder, and the second binder.

[0036] By disposing an adhesive layer having the above-described configuration in contact with the positive electrode active material layer and the solid electrolyte layer, cycle characteristics can be improved. While the mechanism by which this effect is achieved is not completely clear, the following mechanism is presumed. Conventional all-solid-state batteries have a problem of capacity reduction due to repeated charge / discharge cycles. The inventors' investigations have revealed that capacity reduction occurs when the positive electrode active material layer and the adjacent solid electrolyte layer contain binders of different types (compounds). This is thought to be due to a difference in solubility parameters (SP values) between the binder (first binder) contained in the positive electrode active material layer and the binder (second binder) contained in the solid electrolyte layer, which reduces adhesion at the interface between the positive electrode active material layer and the solid electrolyte layer. It is presumed that this leads to delamination between the positive electrode active material layer and the solid electrolyte layer as the positive electrode active material contracts and expands due to charge / discharge reactions, resulting in a deterioration in cycle characteristics. In the all-solid-state battery according to the present embodiment, an adhesive layer containing both the binder (first binder) contained in the positive electrode active material layer and the binder (second binder) contained in the solid electrolyte layer is disposed in contact with the positive electrode active material layer and the solid electrolyte layer, thereby firmly bonding the positive electrode active material layer and the solid electrolyte layer via the adhesive layer. This prevents peeling between the positive electrode active material layer and the solid electrolyte layer even after repeated charge-discharge reactions, improving cycle characteristics. Additionally, in the all-solid-state battery, a pressure member applies a constraining pressure in the stacking direction of the power generating element to maintain contact between the layers. Conventional technology requires a large constraining pressure to prevent peeling between the positive electrode active material layer and the solid electrolyte layer, which also poses a problem of increased weight and volume of the constraining jig. In the all-solid-state battery according to the present embodiment, peeling between the positive electrode active material layer and the solid electrolyte layer can be prevented, thereby simplifying the constraining jig. Therefore, the present embodiment also has the advantage of achieving a further improvement in energy density when installed in a vehicle. The above mechanism is merely based on speculation, and whether it is correct or not does not affect the technical scope of the present invention.

[0037] The specific form of the solid electrolyte contained in the adhesive layer is not particularly limited, and the solid electrolytes exemplified in the section on the positive electrode active material layer and their preferred forms can be similarly adopted. The solid electrolyte contained in the adhesive layer may be the same as or different from the solid electrolyte contained in the solid electrolyte layer. Among them, 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.

[0038] The first binder and the second binder may be the same as those exemplified in the sections for the first binder in the positive electrode active material layer and the second binder in the solid electrolyte layer, as well as their preferred forms. Among these, the first binder is preferably a fibrous binder and the second binder a non-fibrous binder, and more preferably the first binder is polytetrafluoroethylene and the second binder is styrene-butadiene rubber. The use of these binders further strengthens the adhesion between the positive electrode active material layer and the solid electrolyte layer via the adhesive layer, thereby enabling further improvement in the cycle characteristics of the all-solid-state battery.

[0039] The total amount of the first binder and the second binder in the adhesive layer is not particularly limited, but is preferably in the range of 1 to 15% by mass, more preferably in the range of 1.5 to 10% by mass, even more preferably in the range of 2 to 5% by mass, and even more preferably more than 2.5% by mass but not more than 4% by mass, relative to 100% by mass of the total solid content in the adhesive layer. By setting the total amount of the first binder and the second binder within the above range, sufficient adhesiveness can be imparted to the adhesive layer.

[0040] In this embodiment, the ratio of the content of the first binder in the positive electrode active material layer to the total solid content of the positive electrode active material layer is R ｃ (mass%), and the ratio of the total amount of the first binder and the second binder in the adhesive layer to the total solid content of the adhesive layer is R ｄ (mass%), and the ratio of the content of the second binder in the solid electrolyte layer to the total solid content of the solid electrolyte layer is R ｅ (mass%), R ｃ <R ｄ <R ｅ In this case, it is preferable that R ｃ (mass%) is 1 mass% or more and 2.5 mass% or less, and R ｄ (mass%) is more than 2.5 mass% and not more than 4 mass%, and R ｅ It is particularly preferable that the content of the binder (mass %) is more than 4 mass % and not more than 7 mass %. By adopting such a configuration (making the amount of binder contained in the adhesive layer between the amount of binder contained in the positive electrode active material layer and the amount of binder contained in the solid electrolyte layer), the positive electrode active material layer and the solid electrolyte layer can be more firmly bonded via the adhesive layer. As a result, even when charge-discharge reactions are repeated, peeling between the positive electrode active material layer and the solid electrolyte layer is suppressed, and cycle characteristics can be improved.

[0041] In the adhesive layer, the ratio of the content of the first binder to the total amount of the first binder and the second binder is preferably 1% by mass or more and 75% by mass or less, more preferably 1% by mass or more and 67% by mass or less, even more preferably 5% by mass or more and 50% by mass or less, and even more preferably 10% by mass or more and 30% by mass or less. By setting the content ratio of the first binder within the above range, the adhesion at the interface between the positive electrode active material layer and the adhesive layer and the adhesion at the interface between the adhesive layer and the solid electrolyte layer can be further strengthened. As a result, the cycle characteristics of the all-solid-state battery can be further improved.

[0042] In this embodiment, the adhesive layer preferably further contains a positive electrode active material. With this configuration, the adhesive layer contracts and expands during charge and discharge reactions, which can further suppress peeling at the interface between the positive electrode active material layer and the adhesive layer and / or the interface between the adhesive layer and the solid electrolyte layer. The specific form of the positive electrode active material contained in the adhesive layer is not particularly limited, and the positive electrode active materials exemplified in the section on the positive electrode active material layer and their preferred forms can be similarly employed. In particular, the positive electrode active material is 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.

[0043] When the adhesive layer contains a positive electrode active material, the ratio R of the solid electrolyte in the adhesive layer to the total solid content of the adhesive layer ａ (mass %) is the ratio R of the positive electrode active material in the adhesive layer to the total solid content of the adhesive layer ｂ (mass %) (i.e., the content (mass) of the solid electrolyte in the adhesive layer is greater than the content (mass) of the positive electrode active material). By adopting such a configuration, the ionic conductivity of the adhesive layer can be maintained, and the shrinkage and expansion of the adhesive layer due to the charge-discharge reaction is not too large, so that peeling between the solid electrolyte layer and the adhesive layer is further suppressed. As a result, the cycle characteristics of the all-solid-state battery can be further improved.

[0044] In this embodiment, the adhesive layer preferably further contains a conductive additive in addition to the positive electrode active material. This configuration allows the adhesive layer containing the positive electrode active material to maintain an electron conduction path. The specific form of the conductive additive contained in the adhesive layer is not particularly limited, and the conductive additives exemplified in the section on the positive electrode active material layer and their preferred forms can be similarly employed.

[0045] The thickness of the adhesive layer is not particularly limited, but is preferably 1 μm to 100 μm, more preferably 5 μm to 70 μm, and even more preferably 10 μm to 50 μm. When the thickness of the adhesive layer is within the above range, the adhesiveness between the positive electrode active material layer and the solid electrolyte layer via the adhesive layer can be maintained, and a decrease in energy density can be suppressed.

[0046] [Negative Electrode Intermediate Layer] The all-solid-state battery according to this embodiment preferably has 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 contains at least one material 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. The negative electrode intermediate layer is preferably conductive as a whole. 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).

[0047] 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.

[0048] 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 nanofibers (CNF), 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.

[0049] 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.

[0050] 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.

[0051] The negative electrode intermediate layer may further include a binder. The type of binder is not particularly limited, and binders known in the art may 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 includes polyvinylidene fluoride (PVDF), and more preferably is polyvinylidene fluoride (PVDF).

[0052] 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 particles, carbon particles, and binder). When the content of the binder is within the above range, the precipitation and growth of lithium dendrites can be further suppressed.

[0053] The thickness of the negative electrode intermediate layer is not particularly limited, but is preferably 1 μm to 10 μm, more preferably 1.5 μm to 7 μm, and even more preferably 2 μm to 6 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.

[0054] [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 metallic lithium 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 metallic lithium or a lithium-containing alloy, a silicon-based negative electrode active material, or a tin-based negative electrode active material, and particularly preferably contains metallic lithium or a lithium-containing alloy. When metallic lithium 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 charging. Therefore, in this configuration, 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 does not need to be present during full discharge, but in some cases, a negative electrode active material layer made of a certain amount of lithium metal may be present during full discharge.

[0055] The content of the negative electrode active material in the negative electrode active material layer is not particularly limited, but is preferably within the range of 40 to 100 mass %, and more preferably within the range of 50 to 90 mass %, for example.

[0056] The negative electrode active material layer may further contain a solid electrolyte as needed. There are no particular limitations on the specific form of the solid electrolyte contained in the negative electrode active material layer, and the solid electrolytes exemplified in the section on the positive electrode active material layer and their preferred forms may be similarly employed. Among them, 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.

[0057] 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 %, and more preferably in the range of 10 to 50 mass %.

[0058] 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.

[0059] Although one embodiment of the all-solid-state battery of the present invention has been described above, the present invention is not limited to the configuration described in the above embodiment, and can be modified as appropriate based on the claims.

[0060] For example, the type of battery to which the lithium ion secondary battery according to the present invention is applied 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.

[0061] 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).

[0062] The following embodiments are also included within the scope of the present invention: an all-solid-state battery according to claim 1 having the features of claim 2; an all-solid-state battery according to claim 2 having the features of claim 3; an all-solid-state battery according to any one of claims 1 to 3 having the features of claim 4; an all-solid-state battery according to any one of claims 1 to 4 having the features of claim 5; an all-solid-state battery according to claim 4 or 5 having the features of claim 6; an all-solid-state battery according to any one of claims 1 to 6 having the features of claim 7; an all-solid-state battery according to any one of claims 1 to 7 having the features of claim 8; and an all-solid-state battery according to claim 8 having the features of claim 9.

[0063] 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, the instruments and devices used in the glove box were thoroughly dried beforehand.

[0064] <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 an argyrodite-type sulfide solid electrolyte (Li ６ P.S. ５CI), carbon nanofiber (CNF) (VGCF (registered trademark) manufactured by Showa Denko K.K.) as a conductive additive, and polytetrafluoroethylene (PTFE) as a first binder (fibrous binder) were prepared. In a glove box with an argon atmosphere having a dew point of −68°C or lower, the positive electrode active material, solid electrolyte, conductive additive, and PTFE were weighed out to a mass ratio of 80:15.7:2.9:1.4 and kneaded in an agate mortar. After confirming that the binder had fibrillated, the resulting powder composition (positive electrode active material layer-forming mixture) was fed into a powder inlet set in a roll press. The powder composition was then rolled using the roll press (conditions are described below) to form the powder composition into a sheet. The resulting sheet was folded in half, and the folded sheet was again rolled using the roll press (conditions are described below) (folding and rolling process). This folding and rolling process was repeated three times to obtain a positive electrode active material layer having a thickness of 100 μm. In the folding and rolling process, the direction in which the sheet was folded in half and the direction in which the folded sheet was rolled were random. (Conditions of the Roll Press) Roll size: 250 mmφ×400 mm Roll rotation speed: 1 m / min Roll gap: 100 μm Pressure: 10 kN (linear pressure: 25 kN / m).

[0065] (Preparation of Adhesive 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. ５A slurry for preparing an adhesive layer was prepared by mixing 96.5 parts by mass of styrene-butadiene rubber (SBR) as a second binder (non-fibrous binder) dissolved in mesitylene as a solvent. The resulting slurry for preparing an adhesive layer was applied to the surface of a stainless steel foil support using an applicator and dried. The resulting laminate was pressed at 100 MPa, and the support was peeled off to obtain a sheet-like molded product. The sheet-like molded product was then pulverized in an agate mortar. 99.5 parts by mass of the resulting pulverized product was added with 0.5 parts by mass of polytetrafluoroethylene (PTFE) as a first binder (fibrous binder) (the ratio of the content of the first binder to the total amount of the first binder and the second binder was 14% by mass), and the mixture was kneaded in the agate mortar. After confirming that the binder had fibrillated, the resulting powder composition (adhesive layer-forming mixture) was fed into the powder inlet of a roll press. The powder composition was then rolled using a roll press (conditions are shown below) to form the powder composition into a sheet. The resulting sheet was folded in two, and the folded sheet was again rolled using a roll press (conditions are shown below) (folding and rolling). This folding and rolling process was repeated three times to obtain an adhesive layer with a thickness of 40 μm. In the folding and rolling process, the direction in which the sheet was folded in two and the direction in which the folded sheet was rolled were random. (Roll Press Conditions) Roll size: 250 mmφ x 400 mm Roll rotation speed: 1 m / min Roll gap: 40 μm Pressure: 10 kN (linear pressure: 25 kN / m).

[0066] (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. ５A solid electrolyte slurry was prepared by mixing 95 parts by mass of a styrene-butadiene rubber (SBR) second binder (non-fibrous binder) and 5 parts by mass of a binder solution (a styrene-butadiene rubber (SBR) second binder (non-fibrous binder) dissolved in mesitylene as a solvent). The obtained solid electrolyte slurry was applied to the surface of a stainless steel foil support using an applicator and dried to obtain a solid electrolyte layer having a thickness of 40 μm.

[0067] (Preparation of Negative Electrode Intermediate Layer) Acetylene black (AB) and silver (Ag) nanoparticles were weighed and mixed in a mass ratio of AB:Ag = 3:1. 14 parts by mass of polyvinylidene fluoride (PVDF) as a binder was added to 86 parts by mass of the resulting mixture, and N-methylpyrrolidone was added as a solvent and mixed to prepare a negative electrode intermediate layer slurry. The negative electrode intermediate layer slurry was applied to the surface of a stainless steel foil as a negative electrode current collector and dried to obtain a negative electrode intermediate layer having a thickness of 4 μm.

[0068] (Preparation of Evaluation Cell) The positive electrode active material layer and adhesive layer prepared above were stacked in this order on an aluminum foil as a positive electrode current collector. Then, the solid electrolyte layer formed on the stainless steel foil surface prepared above was stacked on the adhesive layer so that the exposed surface of the solid electrolyte layer faced the adhesive layer, and the solid electrolyte layer was transferred onto the adhesive layer by cold isostatic pressing (CIP). After peeling off the stainless steel foil adjacent to the solid electrolyte layer, the negative electrode intermediate layer formed on the stainless steel foil (negative electrode current collector) was stacked on the transferred solid electrolyte layer so that the exposed surface of the solid electrolyte layer faced the exposed surface of the negative electrode intermediate layer, and pressed by cold isostatic pressing (CIP). This resulted in a laminate in which the positive electrode current collector, positive electrode active material layer, adhesive layer, solid electrolyte layer, negative electrode intermediate layer, and negative electrode current collector were stacked in this order. Finally, an aluminum positive electrode tab and a nickel negative electrode tab were joined to the aluminum foil (positive electrode current collector) and the stainless steel foil (negative electrode current collector), respectively, using an ultrasonic welder. The resulting laminate was placed inside an aluminum laminate film and vacuum-sealed, thereby obtaining an evaluation cell that was the lithium deposition-type all-solid-state secondary battery of this example.

[0069] [Example 2] In the above "((Preparation of Adhesive Layer)")", the blending amount of each component was changed to the solid electrolyte (Li６ P.S. ５ The evaluation cell of this example was produced in the same manner as in Example 1, except that the first binder (SBR) was 96.5 parts by mass, the second binder (SBR) was 2 parts by mass, and the first binder (PTFE) was 1.5 parts by mass (the ratio of the content of the first binder to the total amount of the first binder and the second binder was 43% by mass).

[0070] [Example 3] In the above "((Preparation of Adhesive Layer)")", the blending amount of each component was changed to the solid electrolyte (Li ６ P.S. ５ The evaluation cell of this example was produced in the same manner as in Example 1, except that the first binder (SBR) was 96.5 parts by mass, the second binder (SBR) was 1 part by mass, and the first binder (PTFE) was 2.5 parts by mass (the ratio of the content of the first binder to the total amount of the first binder and the second binder was 71% by mass).

[0071] [Example 4] The above "((Preparation of Adhesive Layer))" was carried out by the following method. 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 Cl) 43 parts by mass, and NMC composite oxide (LiNi ０．８ Mn ０．１ Co ０．１ O ２53 parts by mass of carbon nanofiber (CNF) (VGCF (registered trademark) manufactured by Showa Denko K.K.) as a conductive additive, 0.5 parts by mass of a binder solution (3 parts by mass of styrene-butadiene rubber (SBR) as a second binder (non-fibrous binder) dissolved in mesitylene as a solvent) was mixed to prepare a slurry for preparing an adhesive layer. The obtained slurry for preparing an adhesive layer was applied to the surface of a stainless steel foil support using an applicator and dried. The obtained laminate was pressed at 100 MPa, and the support was peeled off to obtain a sheet-like molded product. Next, the sheet-like molded product was pulverized in an agate mortar, and 99.5 parts by mass of the resulting pulverized product was added with 0.5 parts by mass of polytetrafluoroethylene (PTFE) as a first binder (fibrous binder) (the ratio of the content of the first binder to the total amount of the first binder and the second binder was 14% by mass), and kneaded in the agate mortar. After confirming that the binder had fibrillated, the resulting powder composition (adhesive layer-forming mixture) was fed into the powder inlet of a roll press. The powder composition was then rolled using the roll press (conditions are described below) to form the powder composition into a sheet. The resulting sheet was folded in two, and the folded sheet was again rolled using the roll press (conditions are described below) (folding and rolling treatment). This folding and rolling treatment was repeated three times to obtain an adhesive layer with a thickness of 40 μm. In the folding and rolling treatment, the direction in which the sheet was folded in two and the direction in which the folded sheet was rolled were random. (Conditions of the roll press machine) Roll size: 250 mmφ×400 mm Roll rotation speed: 1 m / min Roll gap: 40 μm Pressure: 10 kN (linear pressure: 25 kN / m) Except for the above, the evaluation cell of this example was produced in the same manner as in Example 1.

[0072] [Example 5] In the above "((Preparation of Adhesive Layer)")", the blending amount of each component was changed to the solid electrolyte (Li ６ P.S. ５ Cl) 53 parts by mass, positive electrode active material (LiNi ０．８ Mn ０．１ Co ０．１ O２ The evaluation cell of this example was produced in the same manner as in Example 4, except that the components were 43 parts by mass of the first binder (CNF), 0.5 parts by mass of the conductive additive (CNF), 3 parts by mass of the second binder (SBR), and 0.5 parts by mass of the first binder (PTFE) (the ratio of the content of the first binder to the total amount of the first binder and the second binder was 14% by mass).

[0073] Comparative Example 1 In the above "((Preparation of Adhesive Layer)")", the blending amounts of each component were changed to the solid electrolyte (Li ６ P.S. ５ An evaluation cell for this comparative example was produced in the same manner as in Example 1, except that the first binder (PTFE) was not added, and the second binder (SBR) was 95 parts by mass and 5 parts by mass, respectively.

[0074] <Cycle Test> A cycle test was performed on the evaluation cell prepared above under the following conditions, while applying a restraining pressure of 3 MPa in the stacking direction using a pressure member. Charge and discharge (CC mode) at a charge / discharge rate of 0.5 C was repeated 200 times at 60°C with a cell voltage ranging from 2.5 V to 4.25 V. The ratio (percentage) of the 200th discharge capacity to the first discharge capacity was calculated and defined as the capacity retention rate (%). The results are shown in Table 1 below.

[0075]

[0076] The results shown in Table 1 demonstrate that the present invention can improve the cycle characteristics of all-solid-state batteries. A comparison of Examples 1 to 3 demonstrates that the smaller the ratio of the content of the first binder (PTFE) to the total amount of the first binder (PTFE) and the second binder (SBR) in the adhesive layer (the closer it is to 14 mass%), the more the capacity retention rate improves. A comparison of Examples 1, 4, and 5 demonstrates that the capacity retention rate is further improved by further including a positive electrode active material and a conductive additive in the adhesive layer.

[0077] 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, 16 adhesive 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. An all-solid-state battery comprising a power generating element including: a positive electrode having a positive electrode active material layer containing a positive electrode active material and a first binder; a negative electrode; and a solid electrolyte layer interposed between the positive electrode and the negative electrode and containing a solid electrolyte and a second binder, wherein the first binder and the second binder are different from each other, and the all-solid-state battery further includes an adhesive layer adjacent to a main surface of the positive electrode active material layer facing the solid electrolyte layer and a main surface of the solid electrolyte layer facing the positive electrode active material layer, respectively, and the adhesive layer contains a solid electrolyte, the first binder, and the second binder.

2. The all-solid-state battery according to claim 1, wherein in the adhesive layer, a ratio of a content of the first binder to a total amount of the first binder and the second binder is 1 mass % or more and 75 mass % or less.

3. The all-solid-state battery according to claim 2, wherein in the adhesive layer, a ratio of a content of the first binder to a total amount of the first binder and the second binder is 1 mass % or more and 67 mass % or less.

4. The all-solid-state battery according to claim 1 or 2, wherein the adhesive layer further contains a positive electrode active material.

5. The all-solid-state battery according to claim 4, wherein the adhesive layer further contains a conductive assistant.

6. Ratio R of the solid electrolyte in the adhesive layer to the total solid content of the adhesive layer ａ (mass%) is the ratio R of the positive electrode active material in the adhesive layer to the total solid content of the adhesive layer ｂ (mass%) is greater than 1. The all-solid-state battery according to claim 4.

7. The ratio of the content of the first binder in the positive electrode active material layer to the total solid content of the positive electrode active material layer is R ｃ (mass%), the ratio of the total amount of the first binder and the second binder in the adhesive layer to the total solid content of the adhesive layer is R ｄ (mass%), the ratio of the content of the second binder in the solid electrolyte layer to the total solid content of the solid electrolyte layer is R ｅ (mass%), where R ｃ <R ｄ <R ｅ The all-solid-state battery according to claim 1 or 2, which satisfies the above.

8. The all-solid-state battery according to claim 1 or 2, wherein the first binder is a fibrous binder, and the second binder is a non-fibrous binder.

9. The all-solid-state battery according to claim 8, wherein the first binder is polytetrafluoroethylene and the second binder is styrene-butadiene rubber.

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