Solid electrolyte and solid-state battery

Abstract

The present disclosure provides a solid electrolyte having higher ion conductivity both before and after exposure to the atmosphere. The present disclosure relates to a solid electrolyte containing, in a portion thereof, a glassy substance having an NZSP composition containing Na, Zr, Si, P, and O.

Description

Solid electrolytes and solid batteries

[0001] This disclosure relates to solid electrolytes and solid batteries.

[0002] Rechargeable batteries, which can be repeatedly charged and discharged, have long been used in a variety of applications. For example, rechargeable batteries are used as power sources for electronic devices such as smartphones and laptop computers.

[0003] In secondary batteries, a liquid electrolyte is generally used as a medium for ion transfer that contributes to charging and discharging. In other words, so-called electrolyte solutions are used in secondary batteries. However, safety is generally required in such secondary batteries in terms of preventing electrolyte leakage. Furthermore, since organic solvents used in electrolyte solutions are flammable substances, safety is also required in that respect.

[0004] Therefore, research is underway on solid-state batteries that use solid electrolytes instead of liquid electrolytes. For example, Patent Document 1 describes a NASICON-type solid electrolyte (NZSP composition) with Na ions as the conductive species, which has high Na ion conductivity and is used as an electrolyte for solid-state batteries. Since this ionic conductivity is exhibited in the crystalline state, solid-state batteries are manufactured using solid electrolytes that have been synthesized in the crystalline state beforehand.

[0005] Japanese Patent Publication No. 2015-26483

[0006] The inventors of this application recognized that there are problems that need to be overcome with conventional solid electrolytes and solid-state batteries using such solid electrolytes, and newly identified the need to take countermeasures. Specifically, they identified the following problems.

[0007] The NASICON-type solid electrolyte contained in conventional solid batteries is water and CO2. ２ The reaction with the crystalline particles created a reaction layer on the surface, which inhibited ionic conductivity. This phenomenon was easily caused by exposure to moisture in the atmosphere.

[0008] The present disclosure has been made in view of such problems. That is, the main object of the present disclosure is to provide a solid electrolyte having a higher ionic conductivity before and after exposure to air, and a solid battery including the solid electrolyte.

[0009] The present disclosure relates to a solid electrolyte that partly includes a glassy substance having an NZSP composition containing Na, Zr, Si, P, and O.

[0010] The present disclosure also relates to a sintered solid battery including a positive electrode layer containing a positive electrode active material, a negative electrode layer containing a negative electrode active material, and a solid electrolyte layer, wherein at least one layer selected from the group consisting of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer contains the above solid electrolyte.

[0011] The solid electrolyte according to the present disclosure and the solid battery including the solid electrolyte have a higher ionic conductivity before and after exposure to air.

[0012] An XRD chart for explaining the first peak and the second peak in the solid electrolyte of the present disclosure. An NMR chart of the solid electrolyte collected from the sintered tablet obtained in Example 1 is shown. An NMR chart of the solid electrolyte collected from the sintered tablet obtained in Comparative Example 2 is shown. A graph showing the relationship between the peak intensity ratio and the ionic conductivity (before and after air exposure) for the solid electrolyte manufactured in each example / comparative example.

[0013] Hereinafter, the solid electrolyte and the solid battery of the present disclosure will be described in detail. Although the description will be made with reference to the drawings as necessary, the illustrated content is merely schematic and exemplary for understanding the present disclosure.

[0014] [Solid Electrolyte] The solid electrolyte of this disclosure contains in part a glassy substance having an NZSP composition. More specifically, while substances having an NZSP composition usually exist in a crystalline state, the solid electrolyte of this disclosure is a mixture of a substance having an NZSP composition that is in a glassy state (glassy substance) and a substance having an NZSP composition that is in a crystalline state (crystalline substance). More specifically, the solid electrolyte of this disclosure contains both a portion in a glassy state and a portion in a crystalline state while having an NZSP composition. By thus including in part a glassy substance having an NZSP composition, the solid electrolyte of this disclosure contains water and CO ２ The formation of a reaction layer on the surface due to the reaction is suppressed, resulting in higher ionic conductivity both before and after exposure to the atmosphere. Although the detailed mechanism by which this phenomenon occurs is unknown, one possible factor is that solid electrolytes containing glassy material with an NZSP composition become less permeable (or permeable) to moisture.

[0015] The "higher ionic conductivity" of the solid electrolyte of this disclosure is more effective when the solid electrolyte of this disclosure is used as a component material of a solid-state battery. For this reason, the solid electrolyte of this disclosure is useful as a solid electrolyte included in a solid-state battery, as will be detailed later. For example, if a solid electrolyte has an NZSP composition but is entirely in a crystalline state, its ionic conductivity decreases after exposure to air. Also, for example, if a solid electrolyte has an NZSP composition but is entirely in a glassy state, its inclusion as a component material in a solid-state battery will reduce the ionic conductivity of the solid-state battery.

[0016] The NZSP composition is a chemical composition containing Na (sodium), Zr (zirconium), Si (silicon), P (phosphorus), and O (oxygen), and may further contain at least one element selected from the group consisting of V (vanadium), Nb (niobium), Ta (tantalum), Bi (bismuth), W (tungsten), and Mo (molybdenum). If a solid electrolyte does not have an NZSP composition, for example, if it does not contain at least one element among Na (sodium), Zr (zirconium), Si (silicon), and P (phosphorus), the ionic conductivity will decrease, even if it contains some glassy material.

[0017] An example of an NZSP composition is the chemical composition represented by general formula (1).

[0018]

[0019] In equation (1), x satisfies 0 < x < 3, and from the viewpoint of further improving ionic conductivity before and after exposure to the atmosphere, it preferably satisfies 0.5 ≤ x ≤ 2.8, more preferably 1.0 ≤ x ≤ 2.6, even more preferably 1.3 ≤ x ≤ 2.5, sufficiently preferably 1.6 ≤ x ≤ 2.4, and even more sufficiently preferably 1.8 ≤ x ≤ 2.2.

[0020] A glassy substance is a substance that is not in a crystalline state (i.e., a substance that does not have a crystalline structure), and is in an amorphous state, and in the XRD diffraction pattern, it does not have peaks that originate from the crystalline structure of the composition. The fact that the solid electrolyte of this disclosure contains a glassy substance having an NZSP composition can be confirmed by the following methods (1) to (3). For example, the fact that a solid electrolyte extracted from a solid-state battery contains a glassy substance having an NZSP composition can be confirmed by the following methods (1) to (3). Note that it is not necessary to confirm by all of methods (1) to (3), but it is sufficient to confirm by at least one method selected from methods (1) to (3).

[0021] Method (1) NMR method: Because the atomic coordination environment differs between crystals and glasses, ３１In P NMR measurements, peaks are observed at different chemical shift values. The relative abundance of crystals and glass can be calculated from the integral of the peaks attributed to crystals and the peaks attributed to glass.

[0022] Method (2) XAFS method: Because the atomic coordination environments differ between crystals and glasses, XAFS measurements of constituent elements (e.g., Si-K edge, Na-K edge, P-K edge) show different spectra. By LCF analysis using the spectra of the crystalline and glass raw materials, the abundance ratio of crystals to glass can be calculated.

[0023] Method (3) XRD method: In XRD measurements, crystals show sharp peaks, while glass shows broad peaks. The relative abundance of crystals and glass can be calculated using the Direct Derivation (DD) method, which is one of the quantitative analysis methods. High-energy X-ray diffraction using synchrotron radiation can also be used.

[0024] The proportion of glassy material in the solid electrolyte of this disclosure is not particularly limited, as long as the intensity ratio of the first peak intensity to the second peak intensity (first peak intensity / second peak intensity), as described later, is within a predetermined range.

[0025] In the XRD measurement of the solid electrolyte of this disclosure, the ratio of the first peak intensity appearing at 28.0° to 28.5° in 2θ to the second peak intensity appearing at 13.3° to 14.1° (first peak intensity / second peak intensity) is not particularly limited and may be, for example, 0.0001 or more (particularly 0.0001 or more and 5.0000 or less), and from the viewpoint of further improving ionic conductivity before and after exposure to air, it is preferably greater than 0.001 and less than 2.6. From the viewpoint of further improving ionic conductivity before and after exposure to air, the ratio is more preferably 0.002 or more and 1.000 or less, even more preferably 0.010 or more and 0.500 or less, and sufficiently preferably 0.100 or more and 0.300 or less.

[0026] The intensity ratio between the first and second peak intensities (first peak intensity / second peak intensity) suggests the ratio of crystalline zirconium oxide to crystalline solid electrolyte, as well as the ratio of glass to crystal. This intensity ratio is a ratio related to the peak height in the chart obtained by XRD measurement.

[0027] The glassy substance content in the solid electrolyte of this disclosure is usually greater than 0 mol% and less than 61.0 mol% (particularly 0.1 mol% or more and 50.0 mol% or less) relative to the sum of the crystalline substance and the glassy substance in the solid electrolyte. From the viewpoint of further improving the ionic conductivity before and after exposure to air, it is preferably greater than 0.2 mol% and less than 42 mol%, more preferably 0.3 mol% or more and 20.0 mol% or less, even more preferably 1.0 mol% or more and 10.0 mol% or less, and very preferably 4.5 mol% or more and 8.0 mol% or less.

[0028] The content ratio (mol%) of glassy material in the solid electrolyte of this disclosure corresponds, for example, to the ratio X of glassy material when the ratio of crystals (crystalline material) to glass (glassy material) in NMR measurement is Y:X (X + Y = 100 mol%).

[0029] The composition of the solid electrolyte may be determined by performing SEM-EDS analysis on the solid electrolyte powder or sintered solid electrolyte body, and the elements contained in the solid electrolyte may be identified by EDS analysis. Alternatively, the elements contained in the solid electrolyte may be analyzed using bulk analysis or surface analysis methods such as XPS or SIMS.

[0030] The composition of a solid electrolyte may be quantified, for example, by inductively coupled plasma (ICP) analysis. For instance, ICP analysis may be performed on a solid electrolyte powder to analyze the types, content, and molar ratios of elements contained in the solid electrolyte. Alternatively, quantitative analysis of the solid electrolyte may be performed using XRF, AAS, or the like.

[0031] [Solid-state batteries] In this disclosure, "solid-state battery" broadly refers to a battery whose components are made of solids, and in a narrow sense refers to an all-solid-state battery whose components (particularly preferably all components) are made of solids. In one preferred embodiment, the solid-state battery in this disclosure is a stacked solid-state battery configured such that each layer constituting the battery component unit is stacked on top of each other, preferably such layers are made of a fired body. "Solid-state batteries" include not only primary batteries but also so-called "secondary batteries" that can be repeatedly charged and discharged. The term "secondary battery" is not overly restrictive and may also include, for example, energy storage devices.

[0032] The key feature of this disclosure relates to the solid electrolyte contained in the solid-state battery. The basic configuration of the solid-state battery described below will be explained. However, the configuration of the solid-state battery described here is merely an example for understanding the invention and does not limit the invention.

[0033] The solid-state battery of this disclosure includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer, and typically has a laminated structure in which the positive electrode layer and the negative electrode layer are laminated with the solid electrolyte layer in between. The positive electrode layer and the negative electrode layer may each be laminated in two or more layers, as long as a solid electrolyte layer is provided between them. The solid electrolyte layer may be in contact with the positive electrode layer and the negative electrode layer and sandwiched between them.

[0034] The solid electrolyte of this disclosure is useful as a solid electrolyte included in such a solid battery of this disclosure. Accordingly, the solid battery of this disclosure includes the solid electrolyte of this disclosure as described above. More specifically, the solid electrolyte of this disclosure is included as a solid electrolyte in at least one layer selected from the group consisting of a positive electrode layer, a negative electrode layer, and a solid electrolyte layer. This makes it possible to obtain a solid battery that exhibits higher ionic conductivity both before and after exposure to the atmosphere.

[0035] As such, the solid electrolyte of this disclosure is suitable in terms of ionic conductivity before and after exposure to air, and therefore, it is preferable that the solid electrolyte of this disclosure be included in at least the solid electrolyte layer, and more preferably in the positive electrode layer, the negative electrode layer and the solid electrolyte layer.

[0036] If the positive electrode layer contains the solid electrolyte of the present disclosure, the content of the solid electrolyte of the present disclosure is preferably 10% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, very preferably 90% by mass or more, and even more preferably 100% by mass, based on the total amount of solid electrolyte contained in the positive electrode layer, from the viewpoint of further improving the ionic conductivity before and after exposure to the atmosphere.

[0037] If the negative electrode layer contains the solid electrolyte of the present disclosure, the content of the solid electrolyte of the present disclosure is preferably 10% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, very preferably 90% by mass or more, and even more preferably 100% by mass, based on the total amount of solid electrolyte contained in the negative electrode layer, from the viewpoint of further improving the ionic conductivity before and after exposure to the atmosphere.

[0038] If the solid electrolyte layer contains the solid electrolyte of the present disclosure, the content of the solid electrolyte of the present disclosure is preferably 10% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, very preferably 90% by mass or more, and even more preferably 100% by mass, based on the total amount of solid electrolyte contained in the solid electrolyte layer, from the viewpoint of further improving the ionic conductivity before and after exposure to the atmosphere.

[0039] In a solid-state battery, each of its constituent layers may be formed by firing, and the positive electrode layer, negative electrode layer, and solid electrolyte layer may form fired layers. For example, the positive electrode layer, negative electrode layer, and solid electrolyte layer may each be fired integrally with each other, and therefore the laminate containing the positive electrode layer, negative electrode layer, and solid electrolyte layer may form an integrally fired body.

[0040] The positive electrode layer is an electrode layer containing at least a positive electrode active material. The positive electrode layer may further contain a solid electrolyte. In one aspect, the positive electrode layer is composed of a fired body containing at least positive electrode active material particles and solid electrolyte particles. On the other hand, the negative electrode layer is an electrode containing at least a negative electrode active material. The negative electrode layer may further contain a solid electrolyte. In a preferred aspect, the negative electrode layer is composed of a sintered body containing at least negative electrode active material particles and solid electrolyte particles. The positive electrode layer and the negative electrode layer having such a configuration can also be referred to as a "composite positive electrode body" and a "composite negative electrode body", respectively.

[0041] The positive electrode active material and the negative electrode active material are substances that participate in the transfer of electrons in a solid battery. Ions move (conduct) between the positive electrode layer and the negative electrode layer through the solid electrolyte, and charge and discharge are performed by the transfer of electrons. Each electrode layer of the positive electrode layer and the negative electrode layer may particularly be a layer capable of occluding and releasing sodium ions. That is, the solid battery may be an all-solid-state secondary battery in which sodium ions move between the positive electrode layer and the negative electrode layer through the solid electrolyte to perform charge and discharge of the battery.

[0042] The positive electrode active material contained in the positive electrode layer may be a known material capable of occluding and releasing sodium ions. Examples of the positive electrode active material include at least one selected from the group consisting of sodium-containing phosphate compounds having a NASICON-type structure, sodium-containing phosphate compounds having an olivine-type structure, sodium-containing layered oxides, and sodium-containing oxides having a spinel-type structure. For example, in the case of a sodium-containing phosphate compound, Na ３ V ２ (PO ４ ) ３ , NaCoFe ２ (PO ４ ) ３ , Na ２ Ni ２ Fe(PO ４ ) ３ , Na ３ Fe ２ (PO ４ ) ３ , Na ２ FeP ２ O ７ , Na４ Fe ３ (PO ４ ) ２ (P ２ O ７ ), and as a sodium-containing layered oxide, NaFeO ２ At least one selected from the group consisting of the following is an example. If the positive electrode layer and / or solid electrolyte layer contains the solid electrolyte of this disclosure, the positive electrode active material has the following compositional formula: Na ３＋ｘ V ２－ｘ (PO ４ ) ３ (II) The material may be the material represented by the formula (wherein 0 ≤ x ≤ 1) (hereinafter also referred to as NVP). When the positive electrode active material is NVP, the NVP and the solid electrolyte easily form a good firing bond surface during integral firing. This makes it possible to provide a solid-state battery that is suitable in terms of battery performance.

[0043] In addition, the positive electrode active material may be, for example, an oxide, disulfide, chalcogenide, or conductive polymer. Oxides may be, for example, titanium oxide, vanadium oxide, or manganese dioxide. Disulfides may be, for example, titanium disulfide or molybdenum sulfide. Chalcogenides may be, for example, niobium selenide. Conductive polymers may be, for example, disulfide, polypyrrole, polyaniline, polythiophene, polyparastyrene, polyacetylene, or polyacene.

[0044] The negative electrode active material contained in the negative electrode layer may be a known material capable of intercalating and deintercalating sodium ions. For example, the negative electrode active material may be at least one selected from the group consisting of oxides containing at least one element selected from the group consisting of titanium (Ti), silicon (Si), tin (Sn), chromium (Cr), iron (Fe), niobium (Nb), and molybdenum (Mo), carbon materials such as graphite, sodium-containing phosphate compounds having a nasicone-type structure, sodium-containing phosphate compounds having an olivine-type structure, and sodium-containing oxides having a spinel-type structure. When the negative electrode layer and / or solid electrolyte layer contains the solid electrolyte described above in this disclosure, the negative electrode active material has the following compositional formula: Na ３＋ｘ V ２－ｘ (PO４ ) ３ (II) The material may be the material represented by the formula (wherein 0 ≤ x ≤ 1) (hereinafter also referred to as NVP). By using NVP as the negative electrode active material, a good firing bond surface can be formed between the NVP and the solid electrolyte during integral firing. This provides a solid-state battery that is suitable in terms of battery performance.

[0045] The positive electrode layer and / or negative electrode layer may contain a conductive material. Examples of conductive materials included in the positive electrode layer and negative electrode layer include at least one of metallic materials such as silver, palladium, gold, platinum, aluminum, copper, and nickel, as well as carbon.

[0046] Furthermore, the positive electrode layer and / or negative electrode layer may contain a sintering aid. Examples of sintering aids include at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, boron oxide, silicon oxide, bismuth oxide, and phosphorus oxide.

[0047] In addition, in a solid-state battery, the positive electrode layer and the negative electrode layer may be made of the same material.

[0048] The thicknesses of the positive electrode layer and the negative electrode layer are not particularly limited, but for example, they may be 2 μm or more and 50 μm or less, and more particularly 5 μm or more and 30 μm or less, respectively.

[0049] Although not essential elements of the electrode layer, the positive electrode layer and the negative electrode layer may each comprise a positive electrode current collector layer and a negative electrode current collector layer. The positive electrode current collector layer and the negative electrode current collector layer may each be in the form of foil. However, if greater emphasis is placed on aspects such as improved electronic conductivity through integral sintering, reduction of manufacturing costs for solid-state batteries, and / or reduction of internal resistance of solid-state batteries, the positive electrode current collector layer and the negative electrode current collector layer may each be in the form of a sintered body.

[0050] The positive electrode current collector constituting the positive electrode current collector layer and the negative electrode current collector constituting the negative electrode current collector may be made of materials with high conductivity, such as silver, palladium, gold, platinum, aluminum, copper, and / or nickel. The positive electrode current collector and the negative electrode current collector may each have an electrical connection part for electrically connecting to the outside, and may be configured to be electrically connectable to terminals.

[0051] Furthermore, if the positive electrode current collector layer and the negative electrode current collector layer are in the form of sintered bodies, they may be composed of sintered bodies containing a conductive material and a sintering aid. The conductive material included in the positive electrode current collector layer and the negative electrode current collector layer may be selected from materials similar to those that may be included in the positive electrode layer and the negative electrode layer. The sintering aid included in the positive electrode current collector layer and the negative electrode current collector layer may be selected from materials similar to those that may be included in the positive electrode layer and the negative electrode layer.

[0052] As mentioned above, positive electrode current collector layers and negative electrode current collector layers are not essential for solid-state batteries, and solid-state batteries without such layers are also conceivable. In other words, the solid-state battery included in the package of this disclosure may be a solid-state battery without current collector layers.

[0053] The solid electrolyte layer contains a solid electrolyte through which sodium ions can conduct. In particular, the solid electrolyte layer that forms a battery component in a solid-state battery may be a layer through which lithium ions can conduct between the positive electrode layer and the negative electrode layer. The solid electrolyte layer only needs to be provided between the positive electrode layer and the negative electrode layer. In other words, the solid electrolyte layer may exist around the positive electrode layer and / or the negative electrode layer so as to protrude from between the positive electrode layer and the negative electrode layer.

[0054] The solid electrolyte layer may contain a sintering aid. The sintering aid contained in the solid electrolyte layer may be selected from materials similar to those that may be contained in the positive electrode layer and / or negative electrode layer.

[0055] The thickness of the solid electrolyte layer is not particularly limited. The thickness of the solid electrolyte layer located between the positive electrode layer and the negative electrode layer may be, for example, 1 μm or more and 15 μm or less, and particularly 1 μm or more and 5 μm or less.

[0056] In one embodiment, the positive electrode layer, the negative electrode layer, and / or the solid electrolyte layer may contain a solid electrolyte different from the solid electrolyte of the present disclosure described above. A different solid electrolyte is a solid electrolyte with a different composition from the solid electrolyte of the present disclosure (a solid electrolyte having a composition other than the NZSP composition). Examples of different solid electrolytes include crystalline solid electrolytes, glass-based solid electrolytes, and glass-ceramic solid electrolytes. The positive electrode layer, the negative electrode layer, and / or the solid electrolyte layer may contain one or more of the above-mentioned solid electrolytes.

[0057] Examples of solid electrolytes different from those disclosed herein include sodium-containing phosphate compounds having a nasicone structure, oxides having a perovskite structure, and oxides having a garnet-type or garnet-type similar structure. Examples of sodium-containing phosphate compounds having a nasicone structure include Na ｘ M ｙ (PO ４ ) ３ Examples include (1 ≤ x ≤ 2, 1 ≤ y ≤ 2, and M is at least one selected from the group consisting of Ti, Ge, Al, Ga, and Zr).

[0058] [Method for Manufacturing Solid Electrolyte and Method for Manufacturing Solid-State Battery] The solid electrolyte of this disclosure can be manufactured by first manufacturing a glassy solid electrolyte having an NZSP composition, and then moderately firing it. For this reason, the solid electrolyte of this disclosure can be manufactured, for example, by manufacturing a solid-state battery using a glassy solid electrolyte having an NZSP composition (more specifically, by subjecting a glassy solid electrolyte having an NZSP composition to a method for manufacturing a solid-state battery that includes a moderate firing step). The method for manufacturing the solid electrolyte of this disclosure will be described below in the example of a method for manufacturing a solid-state battery of this disclosure.

[0059] An example of a method for manufacturing a solid-state battery according to this disclosure includes the following steps: First, raw materials for a Na source, a Zr source, a Si source, and a P source (as well as other desired metal sources) are weighed in desired proportions and mixed (mixing step). Next, the resulting mixture is heated and cooled by a glass melting method to produce a glassy solid electrolyte (production step of glassy solid electrolyte). Then, a solid-state battery is manufactured using the obtained glassy solid electrolyte (production step of solid-state battery).

[0060] <Mixing Process> In this process, when mixing the raw materials that will be the source of Na, the raw materials that will be the source of Zr, the raw materials that will be the source of Si, and the raw materials that will be the source of P, the proportion of the raw materials is not particularly limited as long as the solid electrolyte of this disclosure described above can be obtained in the manufacturing process of the solid battery, and may be a proportion that can usually be obtained in a manner that yields a desired chemical composition. For example, sodium oxide (Na) can be used as a raw material that will be the source of Na. ２ Examples include O and trisodium phosphate (Na3PO4). For example, zirconium oxide (ZrO) can be used as a Zr source. ２ Examples include silicon dioxide (SiO₂) as a raw material that serves as a source of Si. ２ Examples include phosphorus pentoxide (P) as a source of phosphorus. ２ O ５ The following are examples. The mixing time is not particularly limited as long as a homogeneous mixture can be obtained, and may be, for example, 1 hour or more and 24 hours or less, and particularly 1 hour or more and 18 hours or less.

[0061] <Manufacturing Process for Glassy Solid Electrolytes> In this process, a glassy solid electrolyte is manufactured by heating the mixture obtained in the mixing process using the glass melting method and then cooling it. The glass melting method is a method of obtaining glass by melting the mixture of raw materials described above. The heating temperature is not particularly limited as long as it is the temperature at which the mixture of raw materials described above melts, and may be, for example, 1000°C to 1500°C, and more particularly 1300°C to 1500°C. The heating time is not particularly limited as long as a uniform molten material can be obtained, and may be, for example, 10 minutes to 120 minutes, and more particularly 60 minutes to 120 minutes. After a uniform molten material is obtained, the glassy solid electrolyte is usually obtained by letting it cool. A glassy solid electrolyte is usually a substance in which the entire solid electrolyte is in a glassy state.

[0062] <Solid-state battery manufacturing process> This process involves manufacturing a solid-state battery using a glassy solid electrolyte (solid-state battery manufacturing process). This process includes the formation of a solid-state battery stacking precursor, a firing process, and the formation of positive and negative electrode terminals.

[0063] The peak intensity ratio (first peak intensity / second peak intensity) and the glassy material content in the solid electrolyte of this disclosure can be controlled by adjusting the firing temperature and firing time in the firing process of the glassy solid electrolyte.

[0064] For example, lowering the firing temperature or shortening the firing time of a glassy solid electrolyte increases the peak intensity ratio (first peak intensity / second peak intensity) and the glassy substance content. Conversely, raising the firing temperature or lengthening the firing time of a glassy solid electrolyte decreases the peak intensity ratio (first peak intensity / second peak intensity) and the glassy substance content.

[0065] The magnitude of the influence of adjusting factors such as the firing temperature and firing time of the glassy solid electrolyte on the peak intensity ratio (first peak intensity / second peak intensity) and the glassy material content differs from one another. Therefore, by independently adjusting these factors, the peak intensity ratio (first peak intensity / second peak intensity) and the glassy material content can be controlled within a desired range.

[0066] (Formation Process of Solid-State Battery Stack Precursors) Solid-state battery stack precursors can be manufactured by printing methods such as screen printing, the green sheet method using green sheets, or a combination of these methods. The following describes in detail the cases where printing and green sheet methods are used, but the method is not limited to these. In other words, solid-state battery stack precursors may be manufactured in accordance with the conventional manufacturing methods for solid-state batteries. Furthermore, the order of description and other chronological matters described below are merely for explanatory purposes and are not necessarily binding.

[0067] In this process, several types of pastes are used as inks, such as paste for the positive electrode layer, paste for the negative electrode layer, paste for the solid electrolyte layer, paste for the positive electrode current collector layer, paste for the negative electrode current collector layer, and paste for the outer layer material. In other words, a solid-state battery stacking precursor with a predetermined structure is formed on a support substrate by applying and drying the paste using a printing method.

[0068] During printing, a solid-state battery stacking precursor corresponding to a predetermined solid-state battery structure can be formed on a substrate by sequentially stacking printed layers with predetermined thickness and pattern shape. The type of pattern formation method is not particularly limited as long as it is a method capable of forming the predetermined pattern, but for example, it may be one or more of the following: screen printing and gravure printing.

[0069] The paste can be prepared by wet mixing predetermined constituent materials for each layer, appropriately selected from the group consisting of positive electrode active material particles, negative electrode active material particles, conductive material, solid electrolyte material, current collector layer material, insulating material, and sintering aid, as well as other materials mentioned above, with an organic vehicle in which an organic material is dissolved in a solvent.

[0070] The paste for the positive electrode layer comprises, for example, positive electrode active material particles, an organic material and a solvent, and optionally a solid electrolyte material and / or a sintering aid. The paste for the positive electrode layer may also contain a glassy solid electrolyte.

[0071] The negative electrode layer paste comprises, for example, negative electrode active material particles, an organic material and a solvent, and optionally a solid electrolyte material and / or a sintering aid. The negative electrode layer paste may also contain a glassy solid electrolyte.

[0072] The paste for the solid electrolyte layer comprises, for example, a solid electrolyte material, an organic material, and a solvent, and optionally a sintering aid. The paste for the solid electrolyte layer may also contain a glassy solid electrolyte.

[0073] The paste for the positive electrode current collector layer comprises a conductive material, an organic material, and a solvent, and optionally a sintering aid.

[0074] The paste for the negative electrode current collector layer comprises a conductive material, an organic material, and a solvent, and optionally a sintering aid.

[0075] The outer layer paste may include, for example, an insulating material, an organic material, and a solvent, and optionally a sintering aid. The outer layer paste may also contain a glassy solid electrolyte.

[0076] The organic material contained in the paste is not particularly limited, but at least one polymer material selected from the group consisting of polyvinyl acetal resin, cellulose resin, polyacrylic resin, polyurethane resin, polyvinyl acetate resin, and polyvinyl alcohol resin can be used.

[0077] The type of solvent is not particularly limited, but may be one or more of the following organic solvents: butyl acetate, N-methylpyrrolidone, toluene, terpineol, and N-methylpyrrolidone.

[0078] In wet mixing, media can be used, specifically the ball mill method or the visco mill method. On the other hand, wet mixing methods that do not use media may also be used, such as the sand mill method, high-pressure homogenizer method, or kneader dispersion method.

[0079] The support substrate is not particularly limited as long as it is a support capable of supporting each paste layer, but for example, it may be a release film with a release treatment applied to one surface. Specifically, a substrate made of a polymer material such as polyethylene terephthalate can be used. If the paste layers are to be subjected to the firing process while remaining on the substrate, the substrate may be one that exhibits heat resistance to the firing temperature.

[0080] Alternatively, a green sheet can be formed from each paste, and the resulting green sheets can be stacked to create a solid-state battery stacking precursor.

[0081] In more detail, the support substrates to which each paste is applied are dried on a hot plate heated to 30°C to 90°C, thereby forming positive electrode layer green sheets, negative electrode layer green sheets, solid electrolyte layer green sheets, positive electrode current collector layer green sheets, negative electrode current collector layer green sheets, and / or outer layer material green sheets, each having a predetermined shape and thickness, on each support substrate (e.g., PET film).

[0082] Next, each green sheet is peeled off the substrate. After peeling, the green sheets of each component are stacked sequentially along the stacking direction to form a solid-state battery stacking precursor. After stacking, a solid electrolyte layer, insulating layer, and / or protective layer may be applied to the side regions of the electrode green sheets by screen printing.

[0083] When a glassy solid electrolyte is used in this process, its average particle size is usually 0.5 μm to 10 μm, and more preferably 0.5 μm to 5 μm, and more preferably 0.5 μm to 3 μm, from the viewpoint of further improving ionic conductivity before and after exposure to air.

[0084] (Firing Process) In the firing process, the solid-state battery stacking precursor is subjected to firing. Although this is merely an example, firing is carried out by removing organic materials by heating in a nitrogen gas atmosphere containing oxygen gas or in air at, for example, 200°C or higher, and then heating in a nitrogen gas atmosphere or in air at, for example, 980°C or higher (particularly 980°C to 1450°C), usually 1050°C to 1350°C (particularly 1100°C to 1300°C), preferably 1050°C to 1250°C, and more preferably 1050°C to 1120°C (firing temperature). Firing may be carried out while pressurizing the solid-state battery stacking precursor in the stacking direction (and possibly in the stacking direction and perpendicular to the stacking direction).

[0085] Through such firing processes, a solid-state battery stack is formed, ultimately resulting in the desired solid-state battery.

[0086] The firing time (i.e., the heating time after the removal of the organic material) is not particularly limited as long as the solid electrolyte of the present disclosure is obtained, and is, for example, 1 hour or more and 48 hours or less, preferably 1 hour or more and 24 hours or less, and more preferably 1 hour or more and 12 hours or less.

[0087] (Process for forming positive and negative terminals) For example, the positive terminal is bonded to the solid battery stack using a conductive adhesive, and the negative terminal is bonded to the solid battery stack using a conductive adhesive. In this way, the positive and negative terminals are attached to the solid battery stack. As a result, the desired solid battery can be obtained.

[0088] This disclosure encompasses the following preferred embodiments: <1> A solid electrolyte comprising a glassy substance having an NZSP composition containing Na, Zr, Si, P, and O. <2> The solid electrolyte according to <1>, wherein the NZSP composition is a chemical composition represented by the following general formula (1). (wherein x satisfies 0 < x < 3) <3> The solid electrolyte according to <1> or <2>, wherein the content of the glassy substance is greater than 0 mol% and less than 61.0 mol%. <4> The solid electrolyte according to <1> or <2>, wherein the content of the glassy substance is 0.1 mol% or more and 50.0 mol% or less. <5> The solid electrolyte according to <1> or <2>, wherein the content of the glassy substance is 0.3 mol% or more and 20.0 mol% or less. <6> The solid electrolyte according to any one of <1> to <5>, wherein in XRD measurement of the solid electrolyte, the ratio of the first peak intensity appearing at 2θ of 28.0° or more and 28.5° or less to the second peak intensity appearing at 13.3° or more and 14.1° or less (first peak intensity / second peak intensity) is greater than 0.001 and less than 2.6. <7> The solid electrolyte according to <6>, wherein the ratio (first peak intensity / second peak intensity) is 0.002 or more and 1.000 or less. <8> The solid electrolyte according to <6>, wherein the ratio (first peak intensity / second peak intensity) is 0.010 or more and 0.500 or less. <9> The solid electrolyte according to any one of <1> to <8>, wherein the solid electrolyte is included in a solid battery. <10> A sintered solid battery comprising a positive electrode layer containing a positive electrode active material, a negative electrode layer containing a negative electrode active material, and a solid electrolyte layer, wherein at least one layer selected from the group consisting of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer contains the solid electrolyte according to any one of <1> to <9>. <11> The solid battery according to <10>, wherein each of the positive electrode layer and the negative electrode layer is a layer capable of intercalating and deintercalating sodium ions. <12> A method for manufacturing a solid battery, comprising: a mixing step of mixing a raw material to be a Na source, a raw material to be a Zr source, a raw material to be a Si source, and a raw material to be a P source; a step of heating and cooling the mixture obtained in the mixing step to obtain a glassy solid electrolyte; and a step of manufacturing a solid battery using the glassy solid electrolyte. <13> The method for manufacturing a solid battery according to <12>, wherein the solid battery is the solid battery described in <10> or <11>.

[0089] The present disclosure will be described in detail below with reference to examples and comparative examples, but the present disclosure is not limited in any way to these examples.

[0090] [Example 1] (Production of solid electrolyte (glass state)) Sodium oxide (Na) is used as a raw material. ２ O, Zirconium Oxide (ZrO) ２ silicon dioxide (SiO₂) ２ and phosphorus pentoxide P ２ O ５ The materials were weighed appropriately to obtain a solid electrolyte with the chemical composition shown in Table 1, and mixed at a rotation speed of approximately 150 rpm for 16 hours (mixing step). The mixture was heated at 1400°C for 60 minutes in an air atmosphere, and then allowed to cool to obtain a solid electrolyte (production step for glassy solid electrolyte). The obtained solid electrolyte was pulverized and used.

[0091] (Manufacturing of sintered tablets (corresponding to the manufacturing process of solid-state batteries)) Solid electrolyte (average particle size 1 μm), butyral resin, and alcohol were thoroughly mixed in a weight ratio of 98:15:140. The alcohol was then removed on a hot plate at 80°C to obtain a solid electrolyte powder coated with butyral resin, which serves as a binder. Next, the solid electrolyte powder was pressed at 90 MPa using a tablet molding machine to form tablets. The obtained tablets were sandwiched between two porous setters and then fired to produce a sintered body. The firing process involved removing the butyral resin by firing at 500°C, followed by firing at 1100°C in an air atmosphere.

[0092] (Measurement of Ionic Conductivity (Before Exposure to Air)) Sintered tablets were dried at 100°C to remove moisture, then metallic Na was attached to both sides and sealed in a 2032 coin cell. Ionic conductivity was calculated by measuring the AC impedance of the sealed cell. A frequency response analyzer (FRA) (Solartron, model 125B) was used for AC impedance measurement. Measurements were performed under the conditions of a frequency range of 0.1 MHz to 1 MHz, an amplitude of ±10 mV, and a temperature of 25°C. Ionic conductivity σ was calculated from the resistance (sum of particle and grain boundary resistance) of each solid electrolyte obtained from the cole-cole plot obtained from the AC impedance measurement, using the following equation (I), and evaluated according to the following criteria: σ = (t / A) × (1 / R) (I) (wherein t: thickness of the sample, A: area of ​​the electrode, R: resistance of the solid electrolyte).

[0093] Criteria: ◎: 4.0 x 10 －４ S / cm or higher (best); ○: 2.0 × 10 －４ S / cm or more 4.0×10 －４ S / cm or less (Excellent); △: 1.0 × 10 －４ S / cm or more 2.0×10 －４ S / cm or less (Good); ▲: 5.0 x 10 －５ S / cm or more 1.0×10 －４ Less than S / cm (Pass: No practical problems); ×: 5.0 × 10 －５ Less than S / cm (Failure: Practical problems exist).

[0094] (Measurement of ionic conductivity (after exposure to air)) Ionic conductivity was measured and evaluated using the same method as described above for "Measurement of ionic conductivity (before exposure to air)," except that sintered tablets that had been left standing in the air for one month were used.

[0095] (Overall Assessment) The worse of the two assessment results, "before atmospheric exposure" and "after atmospheric exposure," is shown as the "Overall Assessment Result."

[0096] [Examples 2-6 and Comparative Example 6] Except for changing the firing temperature after removing the butyral resin during the production of the sintered tablets to the temperature shown in Table 1, the solid electrolyte and sintered tablets were produced and the ionic conductivity was measured before and after exposure to air using the same method as in Example 1.

[0097] [Comparative Examples 1-5] Except for using a solid electrolyte manufactured by the following method and changing the firing temperature after removing the butyral resin during the manufacture of the sintered tablet to the temperature shown in Table 1, the sintered tablets were manufactured and the ionic conductivity was measured before and after exposure to air using the same method as in Example 1.

[0098] (Manufacturing of solid electrolytes (crystalline state)) Sodium carbonate (Na) as a raw material ２ CO ３ Zirconium oxide (ZrO) ４ silicon dioxide (SiO₂) ２ , ammonium dihydrogen phosphate NH ４ H ２ PO ４The materials were weighed appropriately to obtain a solid electrolyte with the chemical composition shown in Table 1, and mixed at a rotation speed of approximately 150 rpm for 16 hours (mixing step). The mixture was heated in an air atmosphere at 900°C for 5 hours, and then heated at 1100°C for 20 hours to obtain a solid electrolyte. The obtained solid electrolyte was pulverized and used.

[0099]

[0100] [Evaluation of the state (crystalline / amorphous) of solid electrolytes (raw materials)] The state (crystalline / amorphous) of the solid electrolytes (raw materials) used in the manufacture of sintered tablets was evaluated. The state evaluation was performed using an X-ray diffractometer (Rigaku Corporation, SmartLab (model number)). Specifically, X-ray diffraction measurements were performed on the solid electrolyte powder under the conditions of 25°C, a scan speed of 4.0° / min, and a measurement angle range of 10° to 60°. The following was confirmed as a result of the analysis. For the solid electrolytes (raw materials) of Examples 1 to 6 and Comparative Example 6, no peaks corresponding to the XRD pattern of a NASICON-type crystal structure (PDF number 00-035-0412) were observed, except for the peak derived from zirconium oxide. Therefore, it was confirmed that they were in a glassy (amorphous) state. On the other hand, for the solid electrolytes (raw materials) of Comparative Examples 1 to 5, peaks corresponding to the XRD pattern of a NASICON-type crystal structure were observed, and it was confirmed that they were in a NASICON-type crystalline state.

[0101] [Evaluation of Peak Intensity Ratio of Solid Electrolyte (Sintered Body)] Solid electrolytes sampled from sintered tablets were evaluated. Samples were obtained by scraping off the solid electrolyte. The peak intensity ratio of the solid electrolyte was determined using an X-ray diffractometer (Rigaku Corporation, SmartLab (model number)). Specifically, X-ray diffraction measurements were performed on the solid electrolyte powder under the conditions of 25°C, a scan speed of 4.0° / min, and a measurement angle range of 10° to 60°. When using CuKα rays, the (-1 1 1) peak of zirconium oxide appearing at 2θ between 28.0° and 28.5° was defined as the first peak, and the (2 0 0) peak of NASICON-type solid electrolyte NZSP appearing at 13.3° to 14.1° was defined as the second peak. The ratio of their peak intensities ((intensity of the first peak) / (intensity of the second peak)) was calculated.

[0102] An example of the first and second peaks is shown in Figure 1. In Figure 1, the first peak is ZrO in the XRD chart of the solid electrolyte. ２ The first peak originates from the first, and the second peak originates from the crystal structure of the NZSP composition in the NASICON-type solid electrolyte. The XRD chart in Figure 1 shows ZrO ２ In addition to the XRD chart of the crystal structure of the NZSP composition, the XRD chart of the solid electrolyte in solid batteries obtained using a glassy solid electrolyte at firing temperatures of 900°C, 1000°C, 1100°C, and 1200°C is also shown.

[0103] [The solid electrolyte contains a portion of a glassy substance having an NZSP composition.] ３１ In the NMR chart based on P NMR, both peaks attributed to crystals and peaks attributed to glass were observed, confirming that the solid electrolyte "partially contains" a glassy substance having an NZSP composition. In contrast, the presence of peaks attributed to crystals and the absence of peaks attributed to glass confirmed that the solid electrolyte "does not contain" a glassy substance having an NZSP composition.

[0104] [Measurement of the glassy substance content in the solid electrolyte of sintered tablets] The solid electrolyte sampled from sintered tablets was evaluated. Samples were taken by scraping off the solid electrolyte. The solid electrolytes sampled in Examples 1 and 5 and Comparative Examples 2 and 6 were filled into sample tubes in a dry room atmosphere and subjected to NMR measurement under the following conditions: • Apparatus: Bruker AVANCE NEO 600 MHz NMR + 4 mmφ MAS probe • Pulse seq.: single pulse • Temperature: Room temperature • Resonance frequency: 242.96 MHz • Pulse width (30° pulse): 1.133 us (150 W) • Magic Angle Spinning (MAS) rotation speed: 12 kHz • Repetition time: 600 s • Number of integrations: 8 • Chemical shift reference: 85% phosphoric acid aqueous solution (0 ppm)

[0105] In the NMR chart, the NMR spectrum of Comparative Example 2, which used crystals as the raw material, was attributed to the crystal, and all other signals were attributed to the glass. The glass component content was then calculated from the peak area ratio.

[0106] For example, Figures 2 and 3 show the NMR charts of the solid electrolytes taken from the sintered tablets obtained in Example 1 and Comparative Example 2, respectively. In Figures 2 and 3, spectrum A represents the spectral peak obtained experimentally.

[0107] First, in Figure 3 (Comparative Example 2), spectrum A was separated into multiple model peaks using the analysis software dmfit. In Figure 3, spectral peaks B, C, and D are the separated model peaks and have the chemical shift values ​​shown in Table 2 (Comparative Example 2). Figure 3 also shows the sum of model peaks B, C, and D, which matches the experimentally obtained spectrum A. Therefore, it was determined that the multiple model peaks B, C, and D separated by the analysis software represent the experimental spectrum A.

[0108]

[0109] Specific solid ３１ The analysis conditions for P NMR are as follows: • Peak separation analysis of the NMR spectrum was performed using the dmfit analysis software following the procedure below. • Up to five model peaks were created according to the spectral shape, and the initial chemical shift values ​​were set to -13, -11, -7, -1, and 7 ppm, respectively. A mixed function of Gaussian and Lorentz functions was used as the function of the model peaks, and the mixing ratio of the Gaussian function (G) and the Lorentz function (L) (xG / (1-x)L) was set as follows.

[0110]

[0111] - The chemical shift value, peak intensity, and full width at half maximum of each model peak were used as variables, and the variables were adjusted so that the difference between the sum of the model peaks and the experimental spectrum was minimized. - The model was fitted to match the measured values. The model was divided into multiple model peaks.

[0112] Next, in Figure 2 (Example 1), the dmfit analysis software was used to separate spectrum A into multiple model peaks. In Figure 2, spectral peaks B to F are the separated model peaks and have the chemical shift values ​​shown in Table 4 (Example 1). Here, among the chemical shift values ​​of the model peaks shown in Table 4 (Example 1), the chemical shift values ​​of model peaks B, C, and D match the chemical shift values ​​of the crystalline components in Table 2, and were determined to be model peaks originating from the crystal, while model peaks E and F were determined to be model peaks originating from the glass. In addition, the sum of the model peaks B, C, D, E, and F is also shown in Figure 2, and it matches the spectrum A obtained experimentally. Therefore, it was determined that the multiple model peaks B, C, D, E, and F separated by the analysis software can represent the experimental spectrum A. The relative value of the sum of peak areas originating from the crystalline components (crystalline material) (Y) and the relative value of the sum of peak areas originating from the glass (X) were calculated, and a transformation was performed so that their sum is 1. The relative value (Y) corresponds to the abundance (mol%) of the crystalline component (crystalline substance), and the relative value (X) corresponds to the abundance (mol%) of the glassy component (glassy substance).

[0113]

[0114] In Examples 2-4 and 6, the glassy substance content was calculated using a converted value. Specifically, the converted value was calculated from the XRD peak intensity ratio. More specifically, the glassy substance content and XRD peak intensity ratio of three measured points (Examples 1 and 5 and Comparative Example 6) were fitted using the least squares method, and the glassy substance content in Examples 2-4 and 6 was calculated using the obtained approximation formula. A logistic function was used for the approximation formula.

[0115] [Evaluation of the chemical composition of solid electrolyte in sintered tablets] The solid electrolyte sampled from sintered tablets was evaluated. Sample collection was performed by scraping off the solid electrolyte. The collected solid electrolyte was subjected to ICP analysis to determine its chemical composition.

[0116] Figure 4 shows the relationship between the peak intensity ratio and ionic conductivity (before and after exposure to air) for the solid electrolytes produced in each example / comparative example.

[0117] From the results in Table 1 and Figure 4, the following is clear: • Solid-state batteries manufactured using a glassy solid electrolyte having an NZSP composition as a raw material (i.e., solid-state batteries containing a solid electrolyte that partially includes a glassy substance having an NZSP composition) exhibit sufficiently high ionic conductivity before and after exposure to the atmosphere. Specifically, these solid-state batteries exhibit sufficiently high ionic conductivity before exposure to the atmosphere, and also exhibit sufficiently high ionic conductivity after exposure to the atmosphere, thus maintaining the battery performance of the solid-state battery. • Although the details of the mechanism related to such phenomena are unknown, it is thought that using glass as a raw material and then firing a solid electrolyte layer containing ZrO2 and glass makes it difficult for moisture to permeate into its interior.

[0118] - A comparison between Example 1 and Comparative Example 2, or between Example 3 and Comparative Example 1, shows that when a glassy solid electrolyte is used as a raw material, the ionic conductivity is higher than when a crystalline solid electrolyte is used as a raw material.

[0119] The solid electrolytes and solid batteries of this disclosure can be used in a variety of fields where battery use or energy storage is anticipated. For illustrative purposes only, the solid batteries of this disclosure can be used in the field of electronics packaging. The solid-state batteries of this disclosure can also be used in the electrical, information and communication fields where mobile devices are used (e.g., the electrical and electronic equipment field or mobile device field, including small electronic devices such as mobile phones, smartphones, laptops and digital cameras, activity trackers, arm computers, electronic paper, wearable devices, RFID tags, card-type electronic money, and smartwatches), household and small industrial applications (e.g., power tools, golf carts, household, caregiving and industrial robots), large industrial applications (e.g., forklifts, elevators, and port cranes), transportation systems (e.g., hybrid vehicles, electric vehicles, buses, trains, electric assist bicycles, electric motorcycles, etc.), power grid applications (e.g., various power generation systems, road conditioners, smart grids, and general household energy storage systems), medical applications (medical equipment such as earphones and hearing aids), pharmaceutical applications (medication management systems, etc.), as well as IoT applications and space and deep-sea applications (e.g., space probes, submersible research vessels, etc.).

Claims

1. A solid electrolyte comprising a glassy substance having an NZSP composition containing Na, Zr, Si, P, and O.

2. The solid electrolyte according to claim 1, wherein the NZSP composition is a chemical composition represented by the following general formula (1). (In the equation, x satisfies 0 < x < 3) 3. The solid electrolyte according to claim 1 or 2, wherein the content of the glassy substance is greater than 0 mol% and less than 61.0 mol%.

4. The solid electrolyte according to claim 1 or 2, wherein the content of the glassy substance is 0.1 mol% or more and 50.0 mol% or less.

5. The solid electrolyte according to claim 1 or 2, wherein the content of the glassy substance is 0.3 mol% or more and 20.0 mol% or less.

6. The solid electrolyte according to any one of claims 1 to 5, wherein, in XRD measurement of the solid electrolyte, the ratio of the first peak intensity appearing at 2θ of 28.0° or more and 28.5° or less to the second peak intensity appearing at 13.3° or more and 14.1° or less (first peak intensity / second peak intensity) is greater than 0.001 and less than 2.

6.

7. The solid electrolyte according to claim 6, wherein the ratio (first peak intensity / second peak intensity) is 0.002 or more and 1.000 or less.

8. The solid electrolyte according to claim 6, wherein the ratio (first peak intensity / second peak intensity) is 0.010 or more and 0.500 or less.

9. The solid electrolyte according to any one of claims 1 to 8, wherein the solid electrolyte is included in a solid battery.

10. A sintered solid-state battery comprising a positive electrode layer containing a positive electrode active material, a negative electrode layer containing a negative electrode active material, and a solid electrolyte layer, wherein at least one layer selected from the group consisting of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer contains the solid electrolyte according to any one of claims 1 to 9.

11. The solid-state battery according to claim 10, wherein each of the positive electrode layer and the negative electrode layer is a layer capable of intercalating and deintercalating sodium ions.

12. A method for manufacturing a solid battery, comprising: a mixing step of mixing raw materials that will be a source of Na, raw materials that will be a source of Zr, raw materials that will be a source of Si, and raw materials that will be a source of P; a step of heating and cooling the mixture obtained in the mixing step to obtain a glassy solid electrolyte; and a step of manufacturing a solid battery using the glassy solid electrolyte.

13. The method for manufacturing a solid battery according to claim 12, wherein the solid battery is the solid battery according to claim 10 or 11.

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