solid-state batteries

Abstract

The present invention provides a solid-state battery having an exterior portion containing oxide ceramics that is sufficiently resistant to reactivity with a solid electrolyte, which can form an exterior portion that is sufficiently resistant to moisture. [Solution] The present invention relates to a solid-state battery having an exterior part 2 comprising an oxide ceramic containing one or more elements (M) selected from the group consisting of Li (lithium); Mg (magnesium); and elements of Groups 4 and 5.

Description

[Technical Field]

[0001] The present invention relates to a solid-state battery. [Background technology]

[0002] In recent years, the demand for batteries as power sources for portable electronic devices such as mobile phones and portable personal computers has expanded significantly. Batteries used for such applications have traditionally used electrolytes (electrolytic solutions) such as organic solvents as a medium for ion migration. However, batteries with the above configurations have the risk of electrolyte leakage. Furthermore, organic solvents and other materials used in the electrolyte solutions are flammable. Therefore, there is a demand for improved battery safety.

[0003] Therefore, in order to improve the safety of batteries, research is being conducted into solid-state batteries that use solid electrolytes instead of electrolytic solutions.

[0004] For example, Patent Documents 1 to 4 propose solid-state batteries having an exterior portion containing oxide ceramics on the outer surface of a battery element including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer therebetween. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO2019 / 167856 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-173212 [Patent Document 3] Japanese Patent Application Laid-Open No. 2003-92092 [Patent Document 4] WO2019 / 181909 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the inventors of the present invention have found that the above-described conventional solid-state batteries have the following new problems: If the oxide ceramics contained in the exterior do not contain Li ions, the solid electrolyte contained in the battery element will react with the oxide ceramics, causing the solid electrolyte to decompose and generate by-products. This is particularly true when using highly reactive solid electrolytes with garnet-type or LISICON-type crystal structures. We found that this side reaction could be suppressed by incorporating Li ions into the oxide ceramics. However, when an exterior part containing Li ions was formed, the moisture resistance of the exterior part itself was reduced.

[0007] An object of the present invention is to provide a solid-state battery capable of forming an exterior part that is sufficiently excellent in terms of moisture resistance and that has an exterior part that contains oxide ceramics that are sufficiently excellent in terms of resistance to reactivity with a solid electrolyte. [Means for solving the problem]

[0008] The present invention provides Li (lithium); Mg (magnesium); and One or more elements (M) selected from the group consisting of elements of Groups 4 and 5 The present invention relates to a solid-state battery having an exterior portion including an oxide ceramic containing [Effects of the Invention]

[0009] According to the present invention, it is possible to form an exterior part that is sufficiently excellent in terms of moisture resistance, and it is possible to provide a solid-state battery having an exterior part that includes an oxide ceramic that is sufficiently excellent in terms of resistance to reactivity with a solid electrolyte. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a solid-state battery of the present invention, which is a combined perspective view and cross-sectional view. [Figure 2]FIG. 2 is a schematic perspective view showing another example of a solid state battery of the present invention. [Figure 3] In Example 4, the data of the XRD measurement results when determining the reactivity resistance are shown. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Solid battery] The present invention provides a solid-state battery. As used herein, the term "solid-state battery" broadly refers to a battery whose components (particularly the electrolyte layer) are made of solids, and in a narrower sense refers to an "all-solid-state battery" whose components (particularly all components) are made of solids. In a preferred embodiment, the solid-state battery of the present invention is a stacked solid-state battery in which the layers constituting the battery units are stacked on top of each other, and preferably each such layer is made of a sintered body. As used herein, the term "solid-state battery" encompasses so-called "secondary batteries" that can be repeatedly charged and discharged, and "primary batteries" that can only be discharged. In a preferred embodiment of the present invention, the "solid-state battery" is a "secondary battery." The term "secondary battery" should not be overly constrained by its name and can also encompass electrochemical devices such as "power storage devices." As used herein, the term "solid electrolyte" refers to a battery that does not contain a gel or liquid electrolyte (liquid).

[0012] As used herein, the term "plan view" refers to the state of an object viewed from above or below along the thickness direction (top view or bottom view) based on the stacking direction of the layers constituting the solid-state battery (described later). Furthermore, the term "cross-sectional view" refers to the cross-sectional state (cross-sectional view) viewed from a direction approximately perpendicular to the thickness direction based on the stacking direction L of the layers constituting the solid-state battery (described later). The term "side view" refers to the state of a solid-state battery viewed from directly to the side in the thickness (height) direction, and is equivalent to a side view. The term "mounted" refers to a placement in which the largest surface (flat surface) constituting the solid-state battery's exterior is the bottom surface. The terms "vertical direction" and "horizontal direction" used directly or indirectly in this specification correspond to the vertical direction and horizontal direction in the drawings, respectively. Unless otherwise specified, the same symbols or symbols refer to the same components or parts or have the same meaning. In a preferred embodiment, the vertical downward direction (i.e., the direction in which gravity acts) can be considered to correspond to the "downward direction," and the opposite direction can be considered to correspond to the "upward direction."

[0013] The solid-state battery of the present invention may have any shape in plan view, and typically has a rectangular shape, including a square and a rectangle.

[0014] The solid-state battery of the present invention has a layered structure (particularly a laminated structure), for example, as shown in Fig. 1. The solid-state battery of the present invention has a battery element 1 and an exterior part 2 covering the surface of the battery element 1, and usually further has an external electrode 3 for extracting the power (particularly the current) generated in the battery element to the outside. Fig. 1 is a schematic cross-sectional view showing an example of the solid-state battery of the present invention.

[0015] (exterior part) The exterior casing 2 is a member covering the outside of the battery element 1 and has the function of covering the battery element 1 to prevent moisture from entering the battery element 1. The exterior casing 2 typically has not only this function but also the function of electrically, physically, and chemically protecting the battery element, and therefore may also be referred to as a protective layer or protective film. The exterior casing 2 includes a main surface exterior casing 2a (e.g., a set of main surface exterior casings 2a) that covers the main surface of the battery element 1 and a side surface exterior casing 2b (e.g., a set of side surface exterior casings 2b) that covers the side surface of the battery element 1. The exterior casing 2 typically has a layer or film form. The exterior casing 2 may be in direct contact with the surface of the battery element 1 (particularly the main surface and / or side surface) or indirect contact via another layer (or film). From the viewpoint of more fully demonstrating the effects of the present invention, it is preferable that the exterior casing 2 be in direct contact with the surface of the battery element 1 (particularly the main surface and / or side surface).

[0016] In the solid-state battery of the present invention, the exterior part 2 contains a specific oxide ceramic. In the present invention, it is sufficient that at least one of the main surface exterior part and the side surface exterior part contains the specific oxide ceramic. From the viewpoint of further improving moisture resistance and reactivity resistance, it is preferable that both the main surface exterior part and the side surface exterior part contain the specific oxide ceramic. In this specification, moisture resistance refers to the property of preventing the intrusion of moisture, and may also refer to the property of being less susceptible to the effects of moisture even under high temperature and humidity conditions (for example, the property of being less susceptible to moisture absorption). The term "anti-reactivity" refers to a property in which the exterior (particularly the oxide ceramic contained in the exterior) is unlikely to react (e.g., undergo a side reaction) with the solid electrolyte contained in the battery element even when fired (e.g., at 800°C for 5 hours). The anti-reactivity may particularly refer to a property in which the oxide ceramic and the solid electrolyte are unlikely to react with each other even when fired together.

[0017] In the present invention, the oxide ceramic contained in the exterior portion contains one or more elements (M) selected from the group consisting of Li (lithium); Mg (magnesium); and elements of Groups 4 and 5. Specifically, the element M is one or more elements selected from the group consisting of Ti (titanium), Zr (zirconium), Hf (hafnium), Ta (tantalum), and Nb (niobium). From the viewpoint of further improving moisture resistance, the element M preferably contains Ti, and more preferably contains only Ti, or Ti and Zr or Ta. In the present invention, when the oxide ceramic contains a combination of Li, Mg, and the element M, an exterior portion with excellent moisture resistance and reactivity resistance can be obtained. If the oxide ceramic does not contain Li, Mg, or the element M, at least one of the properties of moisture resistance and reactivity resistance will be reduced.

[0018] In the oxide ceramic, the molar ratios Li / M and Mg / M are not particularly limited, but from the viewpoint of further improving moisture resistance and reactivity resistance, they are preferably within the following ranges. Li / M Preferably 0 <Li / M≦5; More preferably, 0.8≦Li / M≦4.2; More preferably, 0.8≦Li / M≦2.1. Mg / M Preferably, 0.1≦Mg / M≦9.8; More preferably, 0.3≦Mg / M≦9.8; More preferably, 0.8≦Mg / M≦4.2.

[0019] The Li / M and Mg / M in oxide ceramics are values ​​calculated from the contents (or molar ratios) of Li, Mg, and M measured using a method similar to the analytical method for the chemical composition of oxide ceramics described below.

[0020] The oxide ceramic may have any chemical composition as long as it has the above molar ratio. From the viewpoint of further improving moisture resistance and reactivity resistance, the oxide ceramic preferably has a chemical composition represented by the following general formula (1):

[0021] [ka]

[0022] In formula (1), A is one or more elements selected from the group consisting of Na, K, Rb, Ca, Sr, Ba, Sc, Y, Mo, W, Zn, Al, Ga, Ge, Sn, Sb, and Bi. M is one or more elements selected from the same group as the above-described element M, and from the viewpoint of further improving moisture resistance, it preferably contains one or more elements selected from the group consisting of Ti, Zr, Hf, Nb, and Ta, more preferably contains Ti, and even more preferably contains only Ti, or contains Ti and Zr or Ta.

[0023] In formula (1), α1 / γ and β / γ correspond to the molar ratios Li / M and Mg / M described above, respectively. Therefore, α1 / γ satisfies the same range as the molar ratio Li / M described above, and from the viewpoint of further improving moisture resistance and reactivity resistance, preferably satisfies the preferred range of Li / M, more preferably satisfies the more preferred range of Li / M, and even more preferably satisfies the more preferred range of Li / M. β / γ satisfies the same range as the molar ratio Mg / M described above, and from the viewpoint of further improving moisture resistance and reactivity resistance, preferably satisfies the preferred range of Mg / M, more preferably satisfies the more preferred range of Mg / M, and even more preferably satisfies the more preferred range of Mg / M. δ={α1+aα2+2β+nγ} / 2 (n is the average valence of M and M', and a is the average valence of A) Specifically, n is the average valence of M and M'. The average valence of M and M' is B 1For example, when n1 elements X with a valence of a+, n2 elements Y with a valence of b+, and n3 elements Z with a valence of c+ are recognized, the above-mentioned A 1 This is the same value as the average valence of the a is the average valence of A. For example, if A contains n1 elements X with a valence of a+, n2 elements Y with a valence of b+, and n3 elements Z with a valence of c+, the average valence of A is the value expressed as (n1×a+n2×b+n3×c) / (n1+n2+n3). The oxygen number δ may deviate from the above value by about ±10%, i.e., some oxygen vacancies or interstitial oxygen may be present.

[0024] In formula (1), α1 usually satisfies 0<α1<1.0, and from the viewpoint of further improving moisture resistance and reactivity resistance, preferably satisfies 0.15<α1<0.70, more preferably 0.29≦α1≦0.50. α2 usually satisfies 0≦α2≦1.0, and from the viewpoint of further improving moisture resistance and reactivity resistance, it preferably satisfies 0≦α2≦0.5, and more preferably is 0. β usually satisfies 0<β<1.0, and from the viewpoint of further improving moisture resistance and reactivity resistance, it preferably satisfies 0.03≦β<0.85, and more preferably satisfies 0.25≦β≦0.60. γ usually satisfies 0<γ<1.0, and from the viewpoint of further improving moisture resistance and reactivity resistance, preferably satisfies 0.05<γ<0.35, and more preferably satisfies 0.14≦γ≦0.26.

[0025] The chemical composition of oxide ceramics can be determined by ICP (inductively coupled plasma) analysis, LA-ICP-MS (laser ablation ICP-MS), or other methods. EDX (energy dispersive X-ray spectroscopy) and WDX (wavelength dispersive X-ray spectroscopy) may also be used. Furthermore, the chemical composition may be determined by performing quantitative analysis (composition analysis) on 100 arbitrary points on each of 100 arbitrary sintered particles and calculating the average value.

[0026] The crystal structure of the oxide ceramic is not particularly limited, and may be, for example, a rock salt crystal structure, a spinel crystal structure, a layered rock salt crystal structure, or a mixed phase structure thereof. From the viewpoint of further improving moisture resistance and reactivity resistance, the oxide ceramic preferably has a rock salt crystal structure and / or a spinel crystal structure (particularly a rock salt crystal structure or a mixed phase structure of a rock salt crystal structure and a spinel crystal structure), and more preferably has a rock salt crystal structure.

[0027] The term "rock-salt-type ceramics" used herein does not simply mean that the oxide ceramics have a "rock-salt-type crystal structure," but also encompasses a "rock-salt-type-like crystal structure." Specifically, the oxide ceramics have a crystal structure that can be recognized as a rock-salt-type or rock-salt-like crystal structure by those skilled in the art of solid-state batteries in X-ray diffraction. More specifically, the oxide ceramics may exhibit, in X-ray diffraction, one or more major peaks corresponding to Miller indices specific to the so-called rock-salt-type crystal structure diffraction pattern (ICDD Card No. 00-004-0829) at a predetermined angle of incidence. Alternatively, the oxide ceramics may exhibit one or more major peaks corresponding to Miller indices specific to the so-called rock-salt-type-like crystal structure, which differ in incidence angle (i.e., peak position or diffraction angle) and intensity ratio (i.e., peak intensity or diffraction intensity ratio) due to differences in composition from the one or more major peaks corresponding to Miller indices specific to the so-called rock-salt-type crystal structure. A representative diffraction pattern of a rock-salt-type-like crystal structure is, for example, ICDD Card No. 00-036-0308.

[0028] The expression "oxide ceramics have a spinel-type crystal structure" does not simply mean that the oxide ceramics have a "spinel-type crystal structure," but also encompasses a "spinel-like crystal structure." Specifically, the oxide ceramics have a crystal structure that can be recognized as a spinel-type or spinel-like crystal structure by those skilled in the field of solid-state batteries in X-ray diffraction. More specifically, the oxide ceramics may exhibit, in X-ray diffraction, one or more main peaks corresponding to Miller indices specific to the so-called spinel-type crystal structure diffraction pattern (ICDD Card No. 01-072-6998) at a predetermined angle of incidence, or may exhibit, as a spinel-like crystal structure, one or more main peaks that differ in angle of incidence (i.e., peak position or diffraction angle) and intensity ratio (i.e., peak intensity or diffraction intensity ratio) from one or more main peaks corresponding to Miller indices specific to the so-called spinel-type crystal structure due to differences in composition.

[0029] The oxide ceramic having a mixed phase structure of a rock salt type crystal structure and a spinel type crystal structure means that the oxide ceramic contains oxide ceramic having both the rock salt type crystal structure and the spinel type crystal structure described above.

[0030] The statement that an oxide ceramic has a layered rock-salt crystal structure does not simply mean that the oxide ceramic has a "layered rock-salt crystal structure," but also encompasses a "layered rock-salt-like crystal structure." Specifically, the oxide ceramic has a crystal structure that can be recognized as a layered rock-salt or layered rock-salt-like crystal structure by those skilled in the art of solid-state batteries in X-ray diffraction. More specifically, the oxide ceramic may exhibit, in X-ray diffraction, one or more major peaks corresponding to Miller indices specific to the so-called layered rock-salt crystal structure diffraction pattern (ICDD Card No. 00-033-0831) at a predetermined angle of incidence, or may exhibit one or more major peaks that differ in angle of incidence (i.e., peak position or diffraction angle) and intensity ratio (i.e., peak intensity or diffraction intensity ratio) from one or more major peaks corresponding to Miller indices specific to the so-called layered rock-salt-like crystal structure due to differences in composition. A representative diffraction pattern of a layered rock salt-like crystal structure is, for example, ICDD Card No. 00-033-0843.

[0031] Oxide ceramics may be produced by any method that can produce oxide ceramics of the desired composition. For example, oxide ceramics can be obtained by weighing raw materials containing a Li source, an Mg source, and an M element source to achieve the desired composition, thoroughly mixing them with water, and then firing the mixture. The firing temperature is not particularly limited and may be, for example, 800°C to 1200°C (particularly, 850°C to 1100°C). The firing time is not particularly limited and may be, for example, 1 hour to 10 hours (particularly, 3 hours to 7 hours). For example, lithium carbonate (Li2CO3) can be used as the Li source. For example, magnesium oxide (MgO) can be used as the M source. For example, titanium oxide (TiO2), niobium oxide (Nb2O5), zirconium oxide (ZrO2), tantalum oxide (Ta2O5), and hafnium oxide (HfO2) can be used as the M element source. In the production of oxide ceramics, the final composition of the oxide ceramics is determined by the ratio of the Li source, Mg source, and element M source at the time of charging. Therefore, the molar ratios Li / M and Mg / M can be controlled by adjusting the ratio of the Li source, Mg source, and element M source.

[0032] The present invention does not preclude the exterior portion 2 from containing other oxide ceramics in addition to the specific oxide ceramics described above. Examples of other oxide ceramics include oxides containing Bi. Examples include Li-Bi-O-based oxides, Li-Mg-Bi-O-based oxides, Bi2O3, and Mg-Bi-O-based oxides. The content of the specific oxide ceramics in the exterior portion 2 may typically be an area percentage of 60% to 100%, particularly 90% to 100%. This area percentage can be measured as follows: First, the solid-state battery is fractured so that the fracture surface of the ceramic exterior portion is exposed. This fracture surface is polished using a cross-section polisher or the like to obtain a polished surface. EDX analysis is performed on any surface of the exterior portion on the polished surface. The area where Mg, element M, and element A are detected, and Li is detected by TOF-SIMS, is considered to be the area of ​​the specific oxide ceramics. This can be measured by calculating the area percentage of the oxide ceramic relative to the area of ​​the exterior portion.

[0033] The thickness of the exterior part 2 is preferably 1 μm or more and 500 μm or less, more preferably 5 μm or more and 100 μm or less, and even more preferably 5 μm or more and 50 μm or less. The thickness of the exterior part 2 is the average thickness of thicknesses measured at 100 arbitrary points.

[0034] The relative density of the exterior part 2 is usually 90% or more and 100% or less, and preferably 95% or more and 100% or less. The relative density of the exterior part may be measured using Archimedes' method.

[0035] The exterior part 2 is usually insulating. Insulating means that the exterior part 2 has neither ionic conductivity nor electronic conductivity. For example, the ionic conductivity of the exterior part 2 is usually 1×10 -7 S / cm or less, especially ionic conductivity is 1×10 -10 The ionic conductivity of the exterior part 2 is usually 1×10 -18 For example, the electronic conductivity of the exterior part 2 is usually 1×10 -7 S / cm or less, especially 1×10-10 The electrical conductivity of the exterior 2 is typically 1×10 -18 S / cm or more.

[0036] The oxygen permeability in the thickness direction of the exterior part 2 is, for example, 10 -1 cc / m 2 / day / atmospheric pressure or less, especially 10 -3 cc / m 2 / day / atmospheric pressure or less. The H2O permeability in the thickness direction of the exterior part 2 is, for example, 10 -2 g / m 2 / day and below, especially 10 -4 g / m 2 / day or less. The H2O permeability is measured at 25°C using the cup method, carrier gas method, pressure method, and Ca corrosion method.

[0037] In FIG. 1, the main surface exterior portion 2a and the side surface exterior portion 2b are shown as separate components (or have separate component structures). However, as shown in FIG. 2, the main surface exterior portion 2a and the side surface exterior portion 2b may be integrated (or have an integrated structure). FIG. 2 is a schematic perspective view showing another example of a solid-state battery of the present invention. The solid-state battery of FIG. 2 is similar to the solid-state battery of FIG. 1 except that the main surface exterior portion 2a and the side surface exterior portion 2b are integrated. In the solid-state battery of FIG. 2, the exterior portions of not only the main surface exterior portion 2a but also the side surface exterior portion 2b can be manufactured using a method (green sheet method) for attaching sheets, which will be described later. In particular, manufacturing a solid-state battery (particularly the exterior portion 2) using a sheet in which the sheet corresponding to the main surface exterior portion 2a and the sheet corresponding to the side surface exterior portion 2b are continuous significantly simplifies the manufacturing of the solid-state battery (particularly the exterior portion 2). In this case, the oxide ceramic contained in the main surface exterior portion 2a typically has the same chemical composition as the oxide ceramic contained in the side surface exterior portion 2b.

[0038] When the exterior part 2 is in direct contact with the surface (particularly the main surface and / or side surface) of the battery element 1, it is preferable that the exterior part 2 and the surface be sintered together. In other words, it is preferable that the exterior part 2 be an integral sintered body formed by sintering with the surface (particularly the main surface and / or side surface) of the battery element 1. The exterior part 2 being an integral sintered body formed by sintering with the surface of the battery element 1 means that the exterior part 2 and the battery element 1 are joined by sintering. More specifically, the exterior part 2 and the battery element 1 are both sintered bodies, but are sintered together. Note that the exterior part 2 and the battery element 1 do not necessarily have to be strictly integrated in their entirety, and partial integration is also acceptable. It is sufficient that the exterior part 2 and the battery element 1 are integrated as a whole.

[0039] (battery element) The battery element 1 is the main body of the solid-state battery covered by the exterior part 2 and includes one or more battery structural units. A battery structural unit is the smallest structural unit capable of performing battery functions, and includes a pair of electrode layers 1a (specifically, one positive electrode layer and one negative electrode layer facing each other) and one solid electrolyte layer 1b disposed between the pair of electrode layers 1a (i.e., between the positive electrode layer and the negative electrode layer). The battery element 1 may have a single cell structure having only one battery structural unit, or may have a multi-cell structure in which two or more battery structural units are stacked along the stacking direction of the layers constituting each battery structural unit. The electrode layers include a positive electrode layer and a negative electrode layer. The battery element 1 usually has an insulating part 1c to ensure electrical non-contact between one electrode layer and an external electrode for extracting current from the other electrode layer to the outside. For example, the battery element 1 has an insulating portion 1c for ensuring electrical non-contact between the positive electrode layer and an external electrode (i.e., external negative electrode) for drawing current from the negative electrode layer to the outside. Also, for example, the battery element 1 has an insulating portion 1c for ensuring electrical non-contact between the negative electrode layer and an external electrode (i.e., external negative electrode) for drawing current from the positive electrode layer to the outside. The battery element usually has solid electrolyte layers 1b on the top and bottom layers of the battery element, as shown in FIG.

[0040] The battery element typically includes a solid electrolyte (hereinafter, sometimes referred to as a first solid electrolyte). The first solid electrolyte included in the battery element may have any crystal structure, such as a garnet-type crystal structure, a LISICON-type crystal structure, a perovskite-type crystal structure, or a mixed phase structure thereof. From the viewpoint of further improving moisture resistance and reactivity resistance, the first solid electrolyte included in the battery element preferably has a garnet-type crystal structure, a LISICON-type crystal structure, or a mixed phase structure thereof, and more preferably has a garnet-type crystal structure. The reactivity with the oxide ceramic of the exterior increases in the order of solid electrolytes having a perovskite-type crystal structure, solid electrolytes having a LISICON-type crystal structure, and solid electrolytes having a garnet-type crystal structure. This is because even if the battery element includes such a solid electrolyte, the oxide ceramic of the exterior can more sufficiently suppress the reaction with the solid electrolyte.

[0041] When the battery element includes such a first solid electrolyte, the first solid electrolyte may be contained in one or more layers selected from the positive electrode layer, the negative electrode layer, and the solid electrolyte layer. From the viewpoint of further improving moisture resistance and reactivity resistance, it is preferable that the first solid electrolyte be contained in at least the solid electrolyte layer.

[0042] The term "a solid electrolyte having a garnet-type crystal structure" does not simply mean that the solid electrolyte has a "garnet-type crystal structure," but also encompasses a "garnet-like crystal structure." Specifically, the solid electrolyte has a crystal structure that can be recognized as a garnet-type or garnet-like crystal structure by those skilled in the art of solid-state batteries in X-ray diffraction. More specifically, the solid electrolyte may exhibit, in X-ray diffraction, one or more major peaks corresponding to Miller indices specific to the so-called garnet-type crystal structure diffraction pattern (ICDD Card No. 422259) at a predetermined angle of incidence, or may exhibit one or more major peaks that differ in angle of incidence (i.e., peak position or diffraction angle) and intensity ratio (i.e., peak intensity or diffraction intensity ratio) from one or more major peaks corresponding to Miller indices specific to the so-called garnet-type crystal structure due to differences in composition. A representative diffraction pattern of a garnet-like crystal structure is, for example, ICDD Card No. 00-045-0109.

[0043] The solid electrolyte having a garnet-type crystal structure may have any chemical composition, for example, the chemical composition represented by the following general formula (2).

[0044] [ka]

[0045] In formula (2), A 1 A indicates a metal element that occupies the Li site in the garnet-type crystal structure. 1 is usually one or more elements selected from the group consisting of Ga (gallium), Al (aluminum), Mg (magnesium), Zn (zinc) and Sc (scandium). 1 From the viewpoint of further improving moisture resistance and reactivity resistance, is preferably one or more elements selected from the group consisting of Ga (gallium) and Al (aluminum), and more preferably two elements, Ga and Al.

[0046] In formula (2), B 1 indicates a metal element that occupies the La site in the garnet-type crystal structure. 1 is usually one or more elements selected from the group consisting of Ca (calcium), Sr (strontium), Ba (barium), and lanthanoid elements, such as Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holminium), Er (erbium), Tm (thulium), Yb (ytterbium), and Lu (lutetium).

[0047] In formula (2), D 1 refers to a metal element occupying a hexacoordinated site in a garnet-type crystal structure. The hexacoordinated site of a garnet-type crystal structure is, for example, Li5La3Nb2O 12 Nb-occupied site in (ICDD Card No. 00-045-0109), Li7La3Zr2O 12 (ICDD Card. No. 01-078-6708) is the site occupied by Zr. D 1 represents one or more elements selected from the group consisting of transition elements capable of hexacoordination with oxygen and typical elements belonging to groups 12 to 15. Examples of transition elements capable of hexacoordination with oxygen include Sc (scandium), Zr (zirconium), Ti (titanium), Ta (tantalum), Nb (niobium), Hf (hafnium), Mo (molybdenum), W (tungsten), and Te (tellurium). Examples of typical elements belonging to groups 12 to 15 include In (indium), Ge (germanium), Sn (tin), Pb (lead), Sb (antimony), and Bi (bismuth). D 1is usually one or more elements selected from the group consisting of Zr (zirconium), Sn (tin), Sb (antimony), Ti (titanium), Ta (tantalum), Nb (niobium), Hf (hafnium), Mo (molybdenum), W (tungsten), and Te (tellurium), and from the viewpoint of further improving moisture resistance and reactivity resistance, it preferably contains one or more elements selected from the group consisting of Zr (zirconium), Ta (tantalum), and Nb (niobium), and more preferably contains Zr (zirconium).

[0048] In formula (2), x satisfies 0≦x≦1.00, and from the viewpoint of further improving moisture resistance and reactivity resistance, it preferably satisfies 0≦x≦0.70, more preferably 0≦x≦0.40, even more preferably 0≦x≦0.40, and particularly preferably 0≦x≦0.20. y satisfies 0≦y≦0.50, and from the viewpoint of further improving moisture resistance and reactivity resistance, preferably satisfies 0≦y≦0.40, more preferably 0≦y≦0.30, and even more preferably 0≦y≦0.20. β satisfies 2.5≦β≦3.5, and from the viewpoint of further improving moisture resistance and reactivity resistance, β is preferably 2.7≦β≦3.3, more preferably 2.8≦β≦3.2, and even more preferably 2.9≦β≦3.1. z satisfies 0≦z≦2.00, and from the viewpoint of further improving moisture resistance and reactivity resistance, it preferably satisfies 0≦z≦1.00, more preferably 0≦z≦0.50, and even more preferably 0. γ satisfies 1.5≦γ≦2.5, and from the viewpoint of further improving moisture resistance and reactivity resistance, preferably satisfies 1.7≦γ≦2.3, more preferably 1.8≦γ≦2.2, and even more preferably 1.9≦γ≦2.0.

[0049] In formula (2), p usually satisfies 6.0≦p≦7.0, and from the viewpoint of further improving moisture resistance and reactivity resistance, preferably satisfies 6.0≦p≦6.6, more preferably 6.25≦p≦6.55. a is A 1 is the average valence of A 1 The average valence of is A 1For example, if there are n1 elements X with a valence of a+, n2 elements Y with a valence of b+, and n3 elements Z with a valence of c+, then the value is (n1×a+n2×b+n3×c) / (n1+n2+n3). b is B 1 is the average valence of B 1 The average valence of B 1 For example, when n1 elements X with a valence of a+, n2 elements Y with a valence of b+, and n3 elements Z with a valence of c+ are recognized, the above-mentioned A 1 This is the same value as the average valence of the c is D 1 is the average valence of D 1 The average valence of 1 For example, when n1 elements X with a valence of a+, n2 elements Y with a valence of b+, and n3 elements Z with a valence of c+ are recognized, the above-mentioned A 1 This is the same value as the average valence of the δ indicates the amount of oxygen vacancy, and may be 0. δ usually satisfies 0≦δ<1. The amount of oxygen vacancy δ cannot be quantitatively analyzed even with the latest equipment, so it may be considered to be 0. The molar ratio of each element in the chemical composition of the solid electrolyte ceramic of the present invention does not necessarily coincide with, for example, the molar ratio of each element in formula (2), and tends to deviate from that depending on the analytical method. However, as long as the deviation in composition is not so great as to change the properties, the effects of the present invention can be achieved.

[0050] In the present invention, the chemical composition of the solid electrolyte ceramic may be the composition of the entire ceramic material determined using ICP (inductively coupled plasma). It may also be measured and calculated using ICP-AES (inductively coupled plasma atomic emission spectroscopy) or LA-ICP-MS (laser ablation inductively coupled plasma mass spectroscopy). The chemical composition may also be measured and calculated using XPS analysis, or may be determined using TEM-EDX (energy dispersive X-ray spectroscopy) and / or WDX (wavelength dispersive X-ray spectroscopy). Furthermore, the chemical composition may be obtained by performing quantitative analysis (composition analysis) on 100 arbitrary points on each of 100 arbitrary sintered particles and calculating the average value.

[0051] Specific examples of the garnet-type solid electrolyte represented by the general formula (2) include Li 6.6 La3Zr 1.6 Ta 0.4 O 12 , Li 6.4 Ga 0.05 Al 0.15 La3Zr2O 12 , Li 6.75 La3Zr 1.75 Nb 0.25 O 12 , Li 6.53 La3Zr 1.53 Ta 0.4 Bi 0.07 O 12 Examples include:

[0052] The LISICON-type crystal structure of the solid electrolyte is I structure, β II Type structure, β II 'type structure, T I Type structure, T II Type structure, γ II The LISICON-type solid electrolyte includes the β type structure and the γ type structure. I structure, β II Type structure, β II 'type structure, T I Type structure, T II Type structure, γ IIThe solid electrolyte may contain one or more solid electrolytes having a γ type structure, a γ0 type structure, or a composite structure thereof. The LISICON type structure of the solid electrolyte is preferably a γ type structure from the viewpoint of further improving moisture resistance and reactivity resistance. II A mold structure is preferred.

[0053] The solid electrolyte is γ II The term "having a γ-type structure" means that the solid electrolyte II It means that the solid-state battery has a γ type crystal structure, and in a broad sense, it is known by those skilled in the art of solid-state batteries as II In a narrow sense, a solid electrolyte has a crystal structure that can be recognized as a γ-type crystal structure. II The term "having a γ-type structure" means that the solid electrolyte has a γ-type structure in X-ray diffraction. II γ means that the crystal structure exhibits one or more major peaks corresponding to Miller indices specific to the Li3VO4 type crystal structure at a given angle of incidence. II Compounds having this type structure (i.e., solid electrolytes) are described, for example, in the document "J. Solid State Chem" (AR West et al., J. Solid State Chem., 4, 20-28 (1972)), and an example thereof is ICDD Card No. 01-073-2850.

[0054] The solid electrolyte is β I The term "having a β-type structure" means that the solid electrolyte has a β-type structure. I In a broad sense, it means that the solid-state battery has a β type crystal structure. I In a narrow sense, the term "solid electrolyte" refers to a solid electrolyte having a crystal structure that can be recognized as a β-type crystal structure. I The term "having a β-type structure" means that the solid electrolyte has a β-type structure in X-ray diffraction. I This means that the crystal structure exhibits one or more major peaks corresponding to Miller indices specific to the Li3VO4 type crystal structure at a given angle of incidence. ICompounds having this type structure (i.e., solid electrolytes) are described, for example, in the literature "J. Solid State Chem" (A.R.West et al., J. Solid State Chem., 4, 20-28 (1972)). As an example, the XRD data (d-spacing values ​​and corresponding Miller indices) shown in the table below are shown.

[0055] [Table 1]

[0056] The solid electrolyte is β II The term "having a β-type structure" means that the solid electrolyte has a β-type structure. II In a broad sense, it means that the solid-state battery has a β type crystal structure. II In a narrow sense, the term "solid electrolyte" refers to a solid electrolyte having a crystal structure that can be recognized as a β-type crystal structure. II The term "having a β-type structure" means that the solid electrolyte has a β-type structure in X-ray diffraction. II This means that the crystal structure exhibits one or more major peaks corresponding to Miller indices specific to the Li3VO4 type crystal structure at a given angle of incidence. II Compounds having this type structure (i.e., solid electrolytes) are described, for example, in the literature "J. Solid State Chem" (A.R.West et al., J. Solid State Chem., 4, 20-28 (1972)), and an example thereof is ICDD Card No. 00-024-0675.

[0057] The solid electrolyte is β II The term "having a β' structure" means that the solid electrolyte has a β II It means that the solid-state battery has a β'-type crystal structure, and in a broad sense, it is known by those skilled in the art of solid-state batteries as II In a narrow sense, the term refers to a solid electrolyte having a crystal structure that can be recognized as a β'-type crystal structure. II The term "having a β' type structure" means that the solid electrolyte has a so-called β IIThis means that the crystal structure exhibits one or more major peaks corresponding to Miller indices specific to the β'-Li3VO4 type crystal structure at a given angle of incidence. II Compounds (i.e., solid electrolytes) having the '-type structure are described, for example, in the literature "J. Solid State Chem" (A.R.West et al., J. Solid State Chem., 4, 20-28 (1972)). As an example, the XRD data (d-spacing values ​​and corresponding Miller indices) shown in the table below are shown.

[0058] [Table 2]

[0059] Solid electrolyte is T I The term "having a T type structure" means that the solid electrolyte has a T type structure. I It means that the solid-state battery has a crystal structure of T type. I In a narrow sense, a solid electrolyte has a crystal structure that can be recognized as a T type crystal structure. I The term "having a type structure" means that the solid electrolyte has a so-called T I - This means that the crystal structure of Li3VO4 type shows one or more main peaks corresponding to Miller indices specific to the Li3VO4 type crystal structure at a given angle of incidence. I Compounds having this type structure (i.e., solid electrolytes) are described, for example, in the literature "J. Solid State Chem" (A.R.West et al., J. Solid State Chem., 4, 20-28 (1972)), and an example thereof is ICDD Card No. 00-024-0668.

[0060] Solid electrolyte is T II The term "having a T type structure" means that the solid electrolyte has a T type structure. II It means that the solid-state battery has a crystal structure of T type. II In a narrow sense, a solid electrolyte has a crystal structure that can be recognized as a T type crystal structure. IIThe term "having a type structure" means that the solid electrolyte has a so-called T II - This means that the crystal structure of Li3VO4 type shows one or more main peaks corresponding to Miller indices specific to the Li3VO4 type crystal structure at a given angle of incidence. II Compounds having this type structure (i.e., solid electrolytes) are described, for example, in the literature "J. Solid State Chem" (A.R.West et al., J. Solid State Chem., 4, 20-28 (1972)), and an example thereof is ICDD Card No. 00-024-0669.

[0061] A solid electrolyte having a γ0-type structure means that the solid electrolyte has a γ0-type crystal structure, and in a broad sense, means that the solid electrolyte has a crystal structure that can be recognized as a γ0-type crystal structure by those skilled in the art of solid-state batteries. In a narrow sense, a solid electrolyte having a γ0-type structure means that the solid electrolyte exhibits one or more major peaks in X-ray diffraction at a predetermined angle of incidence, which correspond to Miller indices specific to the so-called γ0-Li3VO4-type crystal structure. Compounds having a γ0-type structure (i.e., solid electrolytes) are described, for example, in the literature "J. Solid State Chem" (A.R.West et al., J. Solid State Chem., 4, 20-28 (1972)). Examples of such compounds include the XRD data (d-spacing values ​​and corresponding Miller indices) shown in the table below.

[0062] [Table 3]

[0063] The solid electrolyte having a LISICON-type crystal structure may have any chemical composition, for example, the chemical composition represented by the following general formula (3).

[0064] [ka]

[0065] In formula (3), A is one or more elements selected from the group consisting of Na (sodium), K (potassium), Mg (magnesium), Ca (calcium), Al (aluminum), Ga (gallium), Zn (zinc), Fe (iron), Cr (chromium), and Co (cobalt). B is one or more elements selected from the group consisting of Zn (zinc), Al (aluminum), Ga (gallium), Si (silicon), Ge (germanium), Sn (tin), P (phosphorus), As (arsenic), Ti (titanium), Mo (molybdenum), W (tungsten), Fe (iron), Cr (chromium), and Co (cobalt), and from the viewpoint of further improving moisture resistance and reactivity resistance, B is preferably one or more elements selected from the group consisting of Si (silicon) and P (phosphorus), and more preferably Si (silicon) or P (phosphorus). x satisfies the relationship 0≦x≦1.0, particularly 0≦x≦0.2, and from the viewpoint of further improving moisture resistance and reactivity resistance, preferably satisfies the relationship 0≦x≦0.1, and more preferably 0. The relationship of y is 0≦y≦1.0, and from the viewpoint of further improving the moisture resistance and the reactivity resistance, the relationship is preferably 0≦y≦0.85. a is the average valence of A. For example, if A contains n1 elements X with a valence of a+, n2 elements Y with a valence of b+, and n3 elements Z with a valence of c+, the average valence of A is the value expressed as (n1×a+n2×b+n3×c) / (n1+n2+n3). b is the average valence of B. For example, when B contains n1 elements X with a valence of a+, n2 elements Y with a valence of b+, and n3 elements Z with a valence of c+, the average valence of B is the same as the average valence of A described above.

[0066] Specific examples of the LISICON-type solid electrolyte represented by the general formula (3) include, for example, Li 3.2 V 0.8 Si 0.2 O4, Li 3.5 P 0.5 Si 0.5 O4 is an example.

[0067] When it is said that a solid electrolyte has a perovskite-type crystal structure, it is meant that the solid electrolyte not only has simply a "perovskite-type crystal structure", but also includes having a "perovskite-type similar crystal structure". Specifically, in X-ray diffraction, the solid electrolyte has a crystal structure that can be recognized as a perovskite-type or perovskite-type similar crystal structure by those skilled in the art in the field of solid-state batteries. More specifically, in X-ray diffraction, the solid electrolyte may show one or more main peaks corresponding to the Miller indices specific to the so-called perovskite-type crystal structure diffraction pattern: ICDD Card No. 00-046-0465 at a predetermined incident angle, or as a perovskite-type similar crystal structure, one or more main peaks corresponding to the Miller indices specific to the so-called perovskite-type crystal structure may show one or more main peaks whose incident angle (i.e., peak position or diffraction angle) and intensity ratio (i.e., peak intensity or diffraction intensity ratio) are different due to the difference in composition. Representative diffraction patterns of perovskite-type similar crystal structures include, for example, ICDD Card No. 00-046-0466, etc.

[0068] The solid electrolyte having a perovskite-type crystal structure may have any chemical composition. The perovskite-type solid electrolyte has, for example, a chemical composition represented by the following general formula (3).

[0069]

Chemical formula

[0070] In formula (4), x is preferably 0.09 < x < 0.167. Further, it is more preferably 0.10 < x < 0.12.

[0071] Specific examples of the perovskite-type solid electrolyte represented by general formula (4) include, for example, Li 0.35 La 0.55 TiO3, Li 0.5 La0.5 Examples include TiO3.

[0072] The chemical composition of the solid electrolyte refers to the average value of the chemical composition of the solid electrolyte in the thickness direction of a layer (e.g., a solid electrolyte layer) containing the solid electrolyte. The chemical composition of the solid electrolyte can be analyzed and measured by breaking the solid battery and performing EDX composition analysis using SEM-EDX (energy dispersive X-ray spectroscopy) in a field of view that includes the entire layer in the thickness direction.

[0073] The solid electrolyte can be obtained by the same method as that for the oxide ceramics described above, except that a raw material compound containing a predetermined metal atom is used, or can be obtained as a commercially available product.

[0074] In order to suppress battery deterioration over the long term, all layers constituting the battery element 1 may be sintered together between two adjacent layers. The phrase "all layers are sintered together between two adjacent layers" means that the two adjacent layers are joined by sintering. Specifically, the two adjacent layers are both sintered bodies, but are sintered together. Strictly speaking, the two adjacent layers do not have to be completely integrated, and partial integration is acceptable. It is sufficient that the two adjacent layers are integrated as a whole. For example, the positive electrode layer 1a, the solid electrolyte layer 1b, and the negative electrode layer 1a may be sintered together in a predetermined stacking order.

[0075] Positive and negative electrode layers The positive electrode layer is a so-called positive electrode active material layer, and may additionally include a positive electrode current collector layer. When the positive electrode layer includes a positive electrode current collector layer, the positive electrode layer may be provided on one side of the positive electrode current collector layer, or on both sides. The positive electrode layer is composed of a sintered body containing positive electrode active material particles, and may typically be composed of a sintered body containing positive electrode active material particles, electron conductive material particles, and solid electrolyte particles contained in the solid electrolyte layer. The positive electrode layer (particularly the positive electrode active material layer) may include the first solid electrolyte described above.

[0076] The negative electrode layer is a so-called negative electrode active material layer, and may additionally include a negative electrode current collecting layer. When the negative electrode layer includes a negative electrode current collecting layer, the negative electrode layer may be provided on one side of the negative electrode current collecting layer, or on both sides of the negative electrode current collecting layer. The negative electrode layer is formed of a sintered body containing negative electrode active material particles, and may be formed of a sintered body containing negative electrode active material particles, electron conductive material particles, and solid electrolyte particles contained in the solid electrolyte layer. The negative electrode layer (particularly the negative electrode active material layer) may include the first solid electrolyte described above.

[0077] The positive electrode active material contained in the positive electrode layer and the negative electrode active material contained in the negative electrode layer are substances involved in the transfer of electrons in a solid-state battery. Charging and discharging are performed by the transfer of electrons caused by the movement (conduction) of ions contained in the solid electrolyte material constituting the solid electrolyte layer between the positive electrode and the negative electrode. The mediator ions are not particularly limited as long as they allow charging and discharging, and examples thereof include lithium ions or sodium ions (particularly lithium ions). The positive electrode layer and the negative electrode layer may be layers capable of absorbing and releasing lithium ions. In other words, the solid-state battery of the present invention may be a solid-state secondary battery in which lithium ions move between the positive electrode and the negative electrode via the solid electrolyte layer to charge and discharge the battery.

[0078] The positive electrode active material contained in the positive electrode layer is not particularly limited, and may be at least one selected from the group consisting of a lithium-containing phosphate compound having a Nasicon structure, a lithium-containing phosphate compound having an olivine structure, a lithium-containing layered oxide, and a lithium-containing oxide having a spinel structure. An example of a lithium-containing phosphate compound having a Nasicon structure is Li3V2(PO4)3. An example of a lithium-containing phosphate compound having an olivine structure is Li3Fe2(PO4)3, LiMnPO4, etc. An example of a lithium-containing layered oxide is LiCoO2, LiCo 1 / 3 Ni 1 / 3 Mn 1 / 3 Examples of lithium-containing oxides having a spinel structure include LiMn2O4, LiNi 0.5 Mn1.5 Examples include O4.

[0079] The negative electrode active material contained in the negative electrode layer is not particularly limited, and examples thereof include at least one selected from the group consisting of an oxide containing at least one element selected from the group consisting of Ti, Si, Sn, Cr, Fe, Nb, and Mo, a graphite-lithium compound, a lithium alloy, a lithium-containing phosphate compound having a Nasicon structure, a lithium-containing phosphate compound having an olivine structure, a lithium-containing oxide having a spinel structure, an oxide having a β-Li3VO4 structure, or an oxide having a γ-Li3VO4 structure. An example of a lithium alloy is Li-Al. An example of a lithium-containing phosphate compound having a Nasicon structure is Li3V2(PO4)3. An example of a lithium-containing phosphate compound having an olivine structure is Li3Fe2(PO4)3. An example of a lithium-containing oxide having a spinel structure is Li4Ti5O. 12 Examples of the negative electrode active material having a β-Li3VO4 type structure include Li3VO4. Examples of oxides having a γ-Li3VO4 type structure include Li 3.2 V 0.8 Si 0.2 Examples include O4.

[0080] The electron conductive material contained in the positive electrode layer and the negative electrode layer is not particularly limited, and examples thereof include metal materials such as silver, palladium, gold, platinum, aluminum, copper, and nickel; and carbon materials. Carbon is particularly preferred because it is less likely to react with the positive electrode active material, the negative electrode active material, and the solid electrolyte material, and is effective in reducing the internal resistance of the solid-state battery.

[0081] The solid electrolyte material contained in the positive electrode layer and the negative electrode layer may be selected, for example, from the same materials as the solid electrolyte material that can be contained in the solid electrolyte layer described below.

[0082] The positive electrode layer and the negative electrode layer may each independently contain a sintering aid, which is not particularly limited and may be, for example, at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, boron oxide, silicon oxide, bismuth oxide, and phosphorus oxide.

[0083] There are no particular limitations on the thickness of the positive electrode layer and the negative electrode layer, and for example, they may each independently be 2 μm or more and 50 μm or less, particularly 5 μm or more and 30 μm or less.

[0084] ·Solid electrolyte layer The solid electrolyte layer may contain a sintering aid. The sintering aid contained in the solid electrolyte layer may be selected from the same materials as the sintering aids that may be contained in the positive electrode layer and the negative electrode layer, for example.

[0085] The thickness of the solid electrolyte layer is not particularly limited, and may be, for example, 1 μm or more and 15 μm or less, particularly 1 μm or more and 5 μm or less.

[0086] (external electrode) The external electrodes 3 are members for externally extracting the power (particularly current) generated in the battery element 1. The external electrodes 3 include a positive external electrode and a negative external electrode. The external electrodes 3 may be in the form of a sintered body from the viewpoints of reducing the manufacturing cost of the solid-state battery by co-firing and reducing the internal resistance of the solid-state battery.

[0087] When the external electrodes 3 are in the form of sintered bodies, they may be composed of, for example, a sintered body containing electron-conductive material particles and a sintering aid. The electron-conductive material contained in the external electrodes 3 may be selected from, for example, materials similar to the electron-conductive materials that may be contained in the positive electrode layer and the negative electrode layer. The sintering aid contained in the external electrodes 3 may be selected from, for example, materials similar to the sintering aids that may be contained in the positive electrode layer and the negative electrode layer.

[0088] [Solid-state battery manufacturing method] The method for producing a solid state battery of the present invention includes: forming a green laminate; and Firing the unfired laminate Includes:

[0089] (Process for forming unfired laminated body) The unfired laminate can be produced by a printing method such as a screen printing method, a green sheet method using a green sheet, a dipping method, or a combination of these methods, but it is clear that the method is not limited to these.

[0090] For example, the solid electrolyte layer and the main surface exterior part are manufactured by the green sheet method. Electrode layers (positive and / or negative electrode layers) and insulating parts are formed on the obtained solid electrolyte layer sheets by a printing method. The solid electrolyte layer sheets and the main surface exterior part sheets on which the electrode layers etc. are printed are stacked in a predetermined order, and then the side exterior parts are formed by a dipping method. Then, the external electrodes are formed by a dipping method. As a result, an unfired laminate is formed.

[0091] (Firing process) The green laminate is subjected to firing, which is carried out by removing the organic material at, for example, 500°C in a nitrogen gas atmosphere containing oxygen gas, and then heating at, for example, 550°C to 1300°C.

[0092] The present invention as described above includes the following preferred embodiments. <1> Li (lithium); Mg (magnesium); and One or more elements (M) selected from the group consisting of elements of Groups 4 and 5 A solid-state battery having an exterior portion including an oxide ceramic containing: <2> The oxide ceramic has the following molar ratio: <1> The solid-state battery according to claim 1. 0 <Li / M≦5 <3> The oxide ceramic has the following molar ratio: <1> or <2> The solid-state battery according to claim 1. 0.1≦Mg / M≦9.8 <4> The oxide ceramic has the following molar ratio: <1> ~ <3> 1. The solid-state battery according to claim 1 , 0.8≦Li / M≦4.2 <5> The oxide ceramic has the following molar ratio: <1> ~ <4> 1. The solid-state battery according to claim 1 , 0.3≦Mg / M≦9.8 <6> The oxide ceramic has the following molar ratio: <1> ~ <5> 1. The solid-state battery according to claim 1 , 0.8≦Li / M≦2.1 <7> The oxide ceramic has the following molar ratio: <1> ~ <6> 1. The solid-state battery according to claim 1 , 0.8≦Mg / M≦4.2 <8> The oxide ceramic has a rock salt type crystal structure, a spinel type crystal structure, a layered rock salt type crystal structure, or a mixed phase structure thereof. <1> ~ <7> 1. The solid-state battery according to claim 1 , <9> The oxide ceramic has a rock salt crystal structure. <1> ~ <8> 1. The solid-state battery according to claim 1 , <10> The element (M) is at least one selected from Ti, Zr, Hf, Ta, and Nb. <1> ~ <9> 1. The solid-state battery according to claim 1 , <11> The element (M) includes Ti or includes Zr and Ta; <1> ~ <10> 1. The solid-state battery according to claim 1 , <12> the solid-state battery further includes a battery element covered by the exterior portion, The battery element contains at least one solid electrolyte selected from a garnet-type solid electrolyte, a LISICON-type solid electrolyte, and a perovskite-type solid electrolyte. <1> ~ <11> 1. The solid-state battery according to claim 1 , <13> The battery element includes a garnet-type solid electrolyte or a LISICON-type solid electrolyte. <12> The solid-state battery according to claim 1. <14> The battery element includes a garnet-type solid electrolyte. <12> or <13> The solid-state battery according to claim 1. <15> The exterior portion has a layered form. <12> ~ <14> 1. The solid-state battery according to claim 1 , <16> The exterior part is in direct contact with the surface of the battery element. <12> ~ <15> 1. The solid-state battery according to claim 1 , <17> The exterior portion is an integral sintered body formed by sintering the surface of the battery element and the sintered body. <12> ~ <16> 1. The solid-state battery according to claim 1 , <18> the battery element includes one or more battery structural units including a positive electrode layer and a negative electrode layer facing each other, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; the solid electrolyte is contained in one or more layers selected from the positive electrode layer, the negative electrode layer, and the solid electrolyte layer; <12> ~ <17> 1. The solid-state battery according to claim 1 ,

[0093] The present invention will be described in more detail below based on specific examples, but the present invention is not limited to the following examples and can be implemented with appropriate modifications within the scope that does not change the gist of the present invention. [Example]

[0094] [Synthesis of oxide ceramics] Raw materials including lithium carbonate (Li2CO3), magnesium oxide (MgO), titanium oxide (TiO2), niobium oxide (Nb2O5), zirconium oxide (ZrO2), tantalum oxide (Ta2O5), and hafnium oxide (HfO2) were weighed out so that the main phase composition would be as shown in the table below. Next, water was added, the mixture was sealed in a polyethylene pot, and the pot was rotated at 150 rpm on a pot rack for 16 hours to mix the raw materials. Note that the lithium carbonate, the Li source, was charged in an amount 5% by mass in excess of the target composition, taking into account Li deficiency during sintering. Next, the obtained slurry was dried and then pre-fired for 5 hours at 1050° C. A mixed solvent of toluene and acetone was added to the obtained pre-fired product, which was then pulverized in a planetary ball mill for 12 hours and then dried to obtain oxide ceramics having the compositions shown in Comparative Examples 5 to 6 and Examples 1 to 26.

[0095] [Moisture resistance evaluation] -Preparation of sintered bodies The resulting oxide ceramic was kneaded with butyral resin, alcohol, and a binder to produce a slurry. The slurry was then formed into a sheet on a PET film using a doctor blade method. The resulting sheets were stacked until they were 1.5 mm thick, and then cut into squares with sides of 10 mm in plan view. To suppress Li volatilization, the stack was thoroughly covered with mother powder and fired at 400°C to remove the butyral resin. The laminate was then fired at 1150-1300°C for 2 hours and then cooled to obtain an exterior ceramic veneer. Using the Archimedes method, it was confirmed that all sintered bodies had a relative density of 95% or higher.

[0096] Testing Method The weight of the exterior ceramic veneer (sintered body) was measured. The sintered body was subjected to a pressure cooker test (PCT) at 125°C and 85% relative humidity for 96 hours, after which the weight of the sintered body was measured again. The weight change before and after the PCT was calculated and evaluated according to the following criteria. The weight change is expressed as a percentage of the weight increase compared to the weight before the PCT. ◎: Weight change was less than 1% (lower limit of measurement) (best); ○: Weight change was 1% or more and less than 5% (excellent); △: Weight change is 5% or more but less than 10% (pass: no practical problems); ×: The weight changed by 10% or more, or the product was powdered (failed: problematic for practical use).

[0097] [Evaluation of reactivity with solid electrolyte] The oxide ceramic was mixed with a solid electrolyte, formed into tablets, and then fired at 800°C for 5 hours. After firing, the crystalline phase was analyzed by XRD measurement and judged according to the following criteria. The tablets produced in each comparative example or each example were crushed in a mortar to form powder. The obtained powder was placed in a folder and subjected to XRD measurement using CuKα radiation at a scan rate of 4.0° / min and a measurement angle range of 10° to 60° to evaluate the crystalline phase contained in the tablets. The solid electrolyte used in comparative examples 1 to 6 and examples 1 to 19 was Li6.6 La3Zr 1.6 Ta 0.4 O 12 The solid electrolytes used in Examples 20 to 26 were the garnet-type solid electrolytes, LISICON-type solid electrolytes, and perovskite-type solid electrolytes shown in Table 7. ○: "No decomposition" of solid electrolyte and oxide ceramics (excellent); △: Partial decomposition of solid electrolyte or oxide ceramic (Pass: Crystalline phase remains) (No practical problems); ×: "Complete decomposition" of the solid electrolyte or oxide ceramic (fail: problematic in practical use).

[0098] "No decomposition" means that in the XRD measurement after firing, all of the peaks derived from the oxide ceramic and the solid electrolyte before firing are clearly observed, and no side reactions between them occur, as shown in Figure 3. Figure 3 shows the XRD measurement results data when determining the reactivity resistance in Example 4. "Partial decomposition" means that in the XRD measurement after firing, all of the peaks derived from the oxide ceramic and solid electrolyte before firing are observed, but a third heterogeneous phase is partially formed. "Complete decomposition" means that in XRD measurement after firing, no peaks of at least one compound among peaks derived from the oxide ceramic before firing and peaks derived from the solid electrolyte are observed.

[0099] The synthesis method of the solid electrolyte used in the reactivity resistance evaluation is shown below.

[0100] [Synthesis of Garnet-Type Solid Electrolyte] Raw materials, including lithium hydroxide monohydrate (LiOH·H2O), gallium oxide (Ga2O3), aluminum oxide (Al2O3), lanthanum hydroxide (La(OH)3), zirconium oxide (ZrO2), niobium oxide (Nb2O5), tantalum oxide (Ta2O5), and bismuth oxide (Bi2O3), were weighed to achieve the desired solid electrolyte composition. Water was then added, the mixture was sealed in a polyethylene pot, and the pot was rotated at 150 rpm for 16 hours on a pot rack to mix the raw materials. To account for Li deficiency during sintering, the lithium source, lithium hydroxide monohydrate (LiOH·H2O), was added in an amount 3% by mass in excess of the target composition. Next, the obtained slurry was dried and then calcined at 1000° C. for 5 hours to obtain a powder of a solid electrolyte having a predetermined composition.

[0101] [Synthesis of LISICON-type solid electrolyte] Raw materials including lithium hydroxide monohydrate (LiOH·H2O), lithium phosphate (Li3PO4), vanadium oxide (VO5), and silicon oxide (SiO2) were weighed to achieve the desired solid electrolyte composition. Water was then added, the mixture was sealed in a polyethylene pot, and the pot was rotated at 150 rpm on a pot rack for 16 hours to mix the raw materials. Furthermore, lithium hydroxide monohydrate (LiOH·H2O), the Li source, was charged in an amount 3% by mass in excess of the target composition, taking into account Li deficiency during sintering. Next, the obtained slurry was dried and then pre-fired at 900° C. for 5 hours to obtain a solid electrolyte powder having a predetermined composition.

[0102] [Synthesis of perovskite-type solid electrolyte] Raw materials including lithium hydroxide monohydrate (LiOH·H2O), titanium oxide (TiO2), and lanthanum hydroxide (La(OH)3) were weighed out so that the solid electrolyte had the desired composition. Water was then added, the mixture was sealed in a polyethylene pot, and the pot was rotated at 150 rpm on a pot rack for 16 hours to mix the raw materials. Furthermore, lithium hydroxide monohydrate (LiOH·H2O), the Li source, was charged in an amount 3% by mass in excess of the target composition, taking into account Li deficiency during sintering. Next, after drying the obtained slurry, it was calcined at 1000 °C for 5 hours to obtain a powder of a solid electrolyte with a predetermined composition.

[0103]

Table 4

[0104] As shown in Comparative Examples 1, 2, and 4, although glass materials, Al2O3, TiO2, etc. have moisture resistance, their reactivity resistance with the solid electrolyte is low and they cannot be used as exterior materials. From Comparative Examples 3 to 6, it was found that the oxide ceramics containing one or two elements selected from Li, Mg, and M (e.g., Ti) used in the present invention have problems either in moisture resistance or reactivity resistance with the solid electrolyte. As shown in Examples 1 to 6, it was found that by including Li, Mg, and M (e.g., Ti) in the oxide ceramics, it is possible to achieve both reactivity resistance and moisture resistance with the solid electrolyte.

[0105]

Table 5

[0106] From the results of Examples 1 to 14, it can be seen that by satisfying the range of 0 < Li / M ≤ 5 and 0.1 ≤ Mg / M ≤ 9.8, it is possible to achieve both moisture resistance and reactivity resistance with the solid electrolyte. Among these, from the perspective of further improving the reactivity resistance with the solid electrolyte, it is preferable that the oxide ceramics have a rock salt structure or a layered rock salt structure. Also, from the perspective of moisture resistance, it is preferable that the oxide ceramics have a rock salt type structure and / or a spinel type structure, and it is more preferable that they have a rock salt type structure.

[0107]

Table 6

[0108] From the results of Examples 15 to 19, it was found that by satisfying the range of 0 < Li / M ≤ 5 and 0.1 ≤ Mg / M ≤ 9.8, even when M is composed of Group 4 and Group 5 elements other than Ti, it is possible to achieve both moisture resistance and reactivity resistance of the solid electrolyte.

[0109] Also, from the comparison between Examples 1 to 5, 7, 9 to 12 and 15 to 19 and Examples 6, 8 and 13 to 14, it was found that if the following conditions A1 to A3 are satisfied, the moisture resistance and the reactivity resistance of the solid electrolyte are further improved, and the judgment of any property becomes "○" or higher: · Condition A1: 0.8 ≤ Li / M ≤ 4.2; · Condition A2: 0.3 ≤ Mg / M ≤ 9.8; · Condition A3: The oxide ceramics have a rock salt structure.

[0110] Furthermore, from the comparison between Examples 2 to 4 and 18 to 19 and Examples 1 and 5 to 17, it was found that if the following conditions B1 to B3 are satisfied, the moisture resistance and the reactivity resistance of the solid electrolyte are further improved, the judgment of moisture resistance becomes "◎", and the judgment of reactivity resistance becomes "○": · Condition B1: 0.8 ≤ Li / M ≤ 2.1; · Condition B2: 0.8 ≤ Mg / M ≤ 4.2; · Condition B3: The oxide ceramics have a rock salt structure.

[0111]

Table 7

[0112] From Examples 20 to 26, it was found that even when various solid electrolytes are used, the oxide ceramics contained in the exterior part in the present invention do not undergo side reactions during firing.

[0113] In Tables 4 to 7, the chemical composition is a compositional formula showing the final composition.

Industrial Applicability

[0114] The solid-state battery of the present invention can be used in various fields where battery use or power storage is envisioned. By way of example only, the solid-state battery of the present invention can be used in the field of electronics packaging. The solid-state battery according to one embodiment of the present invention can also be used in the electrical, information, and communications fields where mobile devices and the like are used (e.g., the electrical and electronic equipment fields including small electronic devices such as mobile phones, smartphones, smart watches, laptops, digital cameras, activity monitors, arm computers, electronic paper, wearable devices, RFID tags, card-type electronic money, and smart watches, or the mobile device field), household and small industrial applications (e.g., power tools, golf carts, and household, nursing care, and industrial robots), large industrial applications (e.g., forklifts, elevators, and harbor cranes), transportation systems (e.g., hybrid cars, electric cars, buses, trains, electrically assisted bicycles, and electric motorcycles), power system applications (e.g., various power generation systems, road conditioners, smart grids, and general household energy storage systems), medical applications (medical devices such as earphones and hearing aids), pharmaceutical applications (medical management systems), IoT fields, and space and deep-sea applications (e.g., space probes, submersible research vessels, and the like). [Explanation of symbols]

[0115] 1: Battery element 1a: Electrode layer (positive electrode layer and negative electrode layer) 1b: Solid electrolyte layer 1c: Insulation part 2:Exterior part 2a: Main surface exterior part 2b: Side exterior part 3: External electrodes (external positive and negative electrodes)

Claims

1. Li (lithium); Mg (magnesium); and One or more elements (M) selected from the group consisting of Group 4 and Group 5 elements A solid-state battery having an exterior portion including an oxide ceramic containing the oxide ceramic has a rock salt type crystal structure, a spinel type crystal structure, a layered rock salt type crystal structure, or a mixed phase structure thereof, The oxide ceramic has the following molar ratio: 0<Li / M≦5

2. 2. The solid-state battery according to claim 1, wherein the oxide ceramic has the following molar ratio: 0.1≦Mg / M≦9.8

3. 2. The solid-state battery according to claim 1, wherein the oxide ceramic has the following molar ratio: 0.8≦Li / M≦4.2

4. 2. The solid-state battery according to claim 1, wherein the oxide ceramic has the following molar ratio: 0.3≦Mg / M≦9.8

5. 2. The solid-state battery according to claim 1, wherein the oxide ceramic has the following molar ratio: 0.8≦Li / M≦2.1

6. 2. The solid-state battery according to claim 1, wherein the oxide ceramic has the following molar ratio: 0.8≦Mg / M≦4.2

7. The solid-state battery according to claim 1 , wherein the oxide ceramic has a rock-salt crystal structure.

8. 2. The solid state battery according to claim 1, wherein the element (M) is at least one selected from the group consisting of Ti, Zr, Hf, Ta, and Nb.

9. The solid-state battery according to claim 1 , wherein the element (M) includes Ti.

10. the solid-state battery further includes a battery element covered by the exterior portion, 2. The solid-state battery according to claim 1, wherein the battery element comprises at least one solid electrolyte selected from a garnet-type solid electrolyte, a LISICON-type solid electrolyte, and a perovskite-type solid electrolyte.

11. 11. The solid-state battery of claim 10, wherein the battery element comprises a garnet-type solid electrolyte or a LISICON-type solid electrolyte.

12. The solid-state battery of claim 10 , wherein the battery element includes a garnet-type solid electrolyte.

13. The solid-state battery according to claim 10 , wherein the exterior portion has a layered form.

14. The solid-state battery according to claim 10 , wherein the exterior portion is in direct contact with a surface of the battery element.

15. The solid-state battery according to claim 10 , wherein the exterior portion is an integral sintered body formed by sintering a surface of the battery element with the sintered body.

16. the battery element includes one or more battery structural units including a positive electrode layer and a negative electrode layer facing each other, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; The solid-state battery according to claim 10 , wherein the solid electrolyte is contained in one or more layers selected from the positive electrode layer, the negative electrode layer, and the solid electrolyte layer.

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