WO2024070660A1 - Solid electrolyte, solid electrolyte layer, and solid electrolyte battery - Google Patents

Abstract

This solid electrolyte contains a compound expressed by formula (1), the peak width at half intensity relative to the intensity of the most-intense peak PA within a range of 200-450 cm−1 in a Raman spectrum being 55 cm−1 or higher, and the peak width at half intensity relative to the intensity of the most-intense peak PB within a range of 80-200 cm−1 being 55 cm−1 or higher.　Formula (1): LiaAbEcJeXfHh (In the formula, A is at least one element selected from alkali metals and alkaline earth metals other than Li; E is at least one element selected from the group consisting of Al, Ga, In, Sc, Y, Ti, Zr, Hf, and lanthanoids; J is at least one group selected from the group consisting of anions; and X is at least one element selected from the group consisting of F, Cl, Br, and I.)

Description

Solid electrolyte, solid electrolyte layer and solid electrolyte battery

The present invention relates to a solid electrolyte, a solid electrolyte layer, and a solid electrolyte battery.
This application claims priority based on Japanese Patent Application No. 2022-157983, filed on September 30, 2022, the contents of which are incorporated herein by reference.

In recent years, electronics technology has made remarkable advances, with efforts being made to make portable electronic devices smaller, lighter, thinner, and more multifunctional. Accordingly, there is a strong demand for batteries, which serve as the power source for electronic devices, to be smaller, lighter, thinner, and more reliable, and solid electrolyte batteries, which use a solid electrolyte as the electrolyte, have attracted attention. Known solid electrolytes include oxide-based solid electrolytes, sulfide-based solid electrolytes, complex hydride-based solid electrolytes, and halide-based solid electrolytes.

For example, Non-Patent Document 1 describes that the ionic conductivity of Li ₃ ScCl ₆ , which is a halide-based solid electrolyte, is 3 mS/cm and that the potential window on the reduction side is 0.91 V (V vs. Li/Li ⁺ ).

JP 2022-122849 A

Jianwen Liang et al., J. Am. Chem. Soc., 2020, 142, pages 7012 to 7022. R.J.H Clark, “The impact of Laser-Raman spectroscopy on inorganic chemistry”, The SPEX Speaker Vol. XVIII, No. 1 (March, 1973)

It is said that halide-based solid electrolytes have higher ionic conductivity than oxide-based solid electrolytes, sulfide-based solid electrolytes, complex hydride-based solid electrolytes, etc. Although the ionic conductivity (3 mS/cm) of Li ₃ ScCl ₆ described in Non-Patent Document 1 is high, there are various limitations, and there are cases where the characteristics described in Non-Patent Document 1 are not expressed as they are, or other substances have to be selected. Therefore, there is a demand for materials that can relatively improve the ionic conductivity among solid electrolytes of similar structure.

Li ₂ ZrCl ₆ and Li ₂ Zr(SO ₄ )Cl ₄ (see, for example, Patent Document 1), which are known as halide-based solid electrolytes, use Zr, which has a high abundance ratio in the earth's crust, as the central metal, and are solid electrolyte materials that are advantageous in terms of resources and cost. However, their ionic conductivity is 4×10 ⁻⁴ S/cm, and the charge/discharge rate characteristics of batteries using these solid electrolytes are insufficient.

The present invention was made in consideration of the above problems, and aims to provide a solid electrolyte, a solid electrolyte layer, and a solid electrolyte battery that have high ionic conductivity.

The present inventors, through extensive research, have succeeded in improving the ionic conductivity of a halide-based solid electrolyte without changing its composition, and have thus completed the present invention.
In order to solve the above problems, the present invention provides the following solutions.

A solid electrolyte according to a first aspect of the present invention includes a compound represented by the following formula (1), and in a Raman spectrum detected by Raman spectroscopy, has one peak each in a range of 200 to 450 cm ⁻¹ and a range of 80 to 200 cm ⁻¹ , where the peak in the range of 200 to 450 cm ⁻¹ is designated as peak A, a straight line connecting starting point 1A and starting point 2A of peak A is designated as baseline A, the peak in the range of 80 to 200 cm ⁻¹ is designated as peak B, and a straight line connecting starting point 1B and starting point 2B of peak B is designated as baseline B, the peak width at half the intensity of the strongest peak P _A from baseline A of peak A is 55 cm ⁻¹ or more, and the peak width at half the intensity of the strongest peak P _B from baseline B is 55 cm ⁻¹ or more;
Li _a A _b E _c J _e X _f H _h ... (1)
(In formula (1), A is at least one element selected from alkali metals other than Li and alkaline earth metals, E is at least one element selected from the group consisting of Al, Ga, In, Sc, Y, Ti, Zr, Hf, and lanthanoids, J is at least one group selected from the group consisting of anions, X is at least one element selected from the group consisting of F, Cl, Br, and I, and 0.5≦a<6, 0≦b<6, 0<c<2, 0<e≦6, 0<f≦6.1, and 0≦h≦0.2.)

The solid electrolyte layer according to aspect 2 of the present invention includes the solid electrolyte of aspect 1.

The solid electrolyte battery according to aspect 3 of the present invention comprises a solid electrolyte layer, a positive electrode, and a negative electrode, and at least one of the positive electrode and the negative electrode contains the solid electrolyte according to aspect 1.

The solid electrolyte battery according to aspect 4 of the present invention comprises the solid electrolyte layer of aspect 2, a positive electrode, and a negative electrode.

According to an aspect of the present invention, a solid electrolyte with high ionic conductivity can be provided.

1 is a graph showing a Raman spectrum of Li ₂ ZrSO ₄ Cl ₄ having high ion conductivity, which is an example of a solid electrolyte according to the present embodiment. FIG. 2 is a diagram for explaining a method 1 for evaluating Raman spectroscopic characteristics, based on a graph in which a portion surrounded by a dotted line and indicated by P1 in the Raman spectrum shown in FIG. 1 is enlarged. FIG. 13 is a diagram for explaining evaluation method 2 of Raman spectroscopic characteristics. FIG. 13 is a diagram for explaining evaluation method 2 of Raman spectroscopic characteristics. 1 is a schematic cross-sectional view of a solid electrolyte battery according to an embodiment of the present invention. FIG. 13 is a diagram showing the Raman spectrum of Example 4, in which the Raman spectroscopic characteristics were evaluated by Evaluation Method 1. FIG. 13 is a diagram showing the Raman spectrum of Example 4, in which the Raman spectroscopic characteristics were evaluated by evaluation method 2. FIG. 2 is a diagram showing the Raman spectrum of Example 25, in which the Raman spectroscopic characteristics were evaluated by evaluation method 1. FIG. 23 is a diagram showing the Raman spectrum of Example 25, in which the Raman spectroscopic characteristics were evaluated by evaluation method 2. FIG. 1 is a diagram showing the Raman spectrum of Comparative Example 1, in which the Raman spectroscopic characteristics were evaluated by Evaluation Method 1. FIG. 13 is a diagram showing the Raman spectrum of Comparative Example 2, in which the Raman spectroscopic characteristics were evaluated by Evaluation Method 1.

The present embodiment will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may show characteristic parts in an enlarged scale for the sake of convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto. The present embodiment can be modified as appropriate within the scope of the technical requirements.
The notation "a±b" indicates a range from the value "a-b" to the value "a+b." Also, the notation "aE-b" indicates the value of "a×10 ^-b ."

"Solid electrolyte"
A solid electrolyte is a material that can move ions when an external electric field is applied. If the ionic conductivity of a solid electrolyte is high, the exchange of ions in the solid electrolyte battery becomes smoother, and the internal resistance becomes smaller.

The solid electrolyte includes a halide-based solid electrolyte represented by Li _{a Ab} E _c J _e X _f H _h ... (1). The solid electrolyte may include a material derived from the raw material powder in addition to the compound represented by the above formula (1). The material derived from the raw material powder is, for example, Li ₂ SO ₄ .

The solid electrolyte may be in the form of a powder (particles) or a sintered body obtained by sintering the powder. The solid electrolyte may also be a compact formed by compressing the powder, a compact formed by molding a mixture of the powder and a binder, or a coating formed by applying a paint containing the powder, a binder, and a solvent and then heating to remove the solvent. The main structure of the solid electrolyte may be amorphous or crystalline.

In formula (1), Li is a lithium ion. a satisfies 0.5≦a<6, preferably 2.0≦a≦4.0, and more preferably 2.5≦a≦3.5. When E is Zr or Hf, a is preferably 1.0≦a≦3.0, and more preferably 1.5≦a≦2.5. In the compound represented by formula (1), if a is 0.5≦a<6, the content of Li contained in the compound is appropriate, and the ionic conductivity of the solid electrolyte layer 10 is high.

In formula (1), A is at least one element selected from alkali metals other than Li and alkaline earth metals. A is substituted for a portion of the Li ions. A is, for example, Na or Ca. When A is Na or Ca, the potential window on the reduction side of the solid electrolyte becomes wider. b satisfies 0≦b<6. Furthermore, a+b satisfies 0.5≦a+b<6.

In formula (1), E is an essential component and is at least one element selected from the group consisting of Al, Ga, In, Sc, Y, Ti, Zr, Hf, and lanthanides (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). E preferably contains Al, Sc, Y, Zr, Hf, and La, and more preferably contains Zr and Y. E improves the ionic conductivity of the solid electrolyte. c is 0<c<2. Since the effect of including E can be obtained more effectively, c is preferably 0.6≦c. Furthermore, E is an element that forms the skeleton of the solid electrolyte. c is more preferably c≦1.

In formula (1), J is at least one group selected from the group consisting of anions. For example, the anions are OH, _BO2 , _BO3 , BO4, _B3O6 , _B4O7 , _CO3 , _NO3 , _AlO2 , _{SiO3 , SiO4, Si2O7, Si3O9, Si4O11 , Si6O18 , PO3 , PO4 , P2O7 , P3O10 , SO3 , SO4 , SO5 , S2O3 , S2O4 , S2O5, S2O6, S2O7 , S2O8 , BF4 , PF6 , BOB , ( COO ) 2} , _N , _{AlCl4 , CF3SO3} At least one group selected from the group consisting of CH ₃ COO, CF ₃ COO, OOC—(CH ₂ ) ₂ —COO, OOC—CH ₂ —COO, OOC—CH(OH)—CH(OH)—COO, OOC—CH(OH)—CH ₂ —COO, C ₆ H ₅ SO ₃ , OOC—CH═CH—COO, C(OH)(CH ₂ COOH) ₂ COO, AsO ₄ , BiO ₄ , CrO ₄ , MnO ₄ , PtF ₆ , PtCl _{6 , PtBr 6 , PtI 6 , SbO 4} , SeO ₄ , TeO ₄ , HCOO, CH ₃ COO, and O (BOB is bis(oxalato borate, OOC—(CH ₂ ) _... -COO is the anion of succinic acid, OOC-CH ₂ -COO is the anion of malonic acid, OOC-CH(OH)-CH(OH)-COO is the anion of tartaric acid, OOC-CH(OH)-CH ₂ -COO is the anion of malic acid, C ₆ H ₅ SO ₃ is the anion of benzenesulfonic acid, OOC-CH=CH-COO (trans form) is the anion of fumaric acid, OOC-CH=CH-COO (cis form) is the anion of maleic acid, and C(OH)(CH ₂ COOH) ₂ COO is the anion of citric acid.
By selecting the above anions as the group, high ionic conductivity is obtained and reduction resistance is improved.

e satisfies 0≦e≦6. e is preferably 0.5≦e because the effect of widening the potential window on the reduction side due to the inclusion of J is more pronounced. e is preferably e≦3 so that the ionic conductivity of the solid electrolyte does not decrease due to an excessively high J content.

X is at least one selected from the group consisting of F, Cl, Br, and I. In order to increase the ionic conductivity of the solid electrolyte, X is preferably at least one selected from the group consisting of Cl, Br, and I, and preferably contains either one or both of Br and I, and particularly preferably contains I. When X contains F, X becomes a solid electrolyte with high ionic conductivity, so it is preferable that X contains F and two or more selected from the group consisting of Cl, Br, and I.

When X is F, the resulting solid electrolyte has sufficiently high ionic conductivity and excellent oxidation resistance. When X is Cl, the resulting solid electrolyte has high ionic conductivity and a good balance of oxidation resistance and reduction resistance. When X is Br, the resulting solid electrolyte has sufficiently high ionic conductivity and a good balance of oxidation resistance and reduction resistance. When X is I, the resulting solid electrolyte has high ionic conductivity.

f satisfies 0<f≦6.1. It is preferable that f is 1≦f. If f is 1≦f, the strength of the pellets will be high when the solid electrolyte is pressure-molded into pellets. If f is 1≦f, the ionic conductivity of the solid electrolyte will be high. It is preferable that f is ≦5 so that the potential window of the solid electrolyte is not narrowed due to a shortage of sulfate caused by an excessively high content of X.

In formula (1), H is hydrogen. h satisfies 0≦h≦0.2.

_Examples of _solid electrolytes _{include Li2ZrSO4Cl4 , Li3YSO4Cl4 , Li3ScSO4Cl4 , and Li3InSO4Cl4 .}

(Raman Spectroscopic Characteristics (Evaluation Method 1))
The solid electrolyte according to this embodiment has one peak in each of the range of 200 to 450 cm ⁻¹ and the range of 80 to 200 cm ⁻¹ in a Raman spectrum detected by Raman spectroscopy, and when the peak in the range of 200 to 450 cm ⁻¹ is defined as peak A, the baseline A connecting the starting point 1A and the starting point 2A of the peak A is defined as peak B, and the baseline B connecting the starting point 1B and the starting point 2B of the peak B is defined as peak B, the peak width at half the intensity of ^the strongest peak from the baseline A of the peak A is 55 cm ⁻¹ or more, and the peak width at half the intensity of the strongest peak from the baseline B of the peak B is 55 cm ⁻¹ or more. The Raman spectroscopic characteristics by the evaluation method 1 will be described in detail below.

Here, in Raman spectroscopy, light is incident on a substance, and the substance is evaluated from the Raman scattered light having a different wavelength from the incident light, and since the difference in wavelength between the Raman scattered light and the incident light corresponds to the vibration energy of the substance, various physical properties of the substance can be investigated from the Raman spectrum. As a result of intensive research, the present inventor has found that it is possible to improve ionic conductivity without changing the composition, and that the improvement in ionic conductivity correlates with the characteristics of the Raman spectrum.
In the case of a solid having a regular crystal lattice and high crystallinity, the peaks corresponding to each vibration energy are sharp, but broad peaks reflect disorder in crystallinity (promotion of amorphous structure). The inventors discovered that by synthesizing a solid electrolyte with the same composition so that the crystallinity is low (promotion of amorphous structure), the ionic conductivity is increased, and the peaks in the Raman spectrum are broadened, reflecting the promotion of the amorphous structure, and thus arrived at the present invention.

A "peak portion" is an overlap of multiple peaks, and in the solid electrolyte that is the subject of this embodiment, there are two overlapping bundles of multiple peaks, one in the range of 200 to 450 cm ^-1 and one in the range of 80 to 200 cm ^-1 . The "peak portion" varies in strength reflecting the overlap of peaks, but does not touch baseline A or baseline B except at two points of contact with the spectrum that is the starting point of the baseline (when it does not touch, it is evaluated as being the same "peak portion").

Fig. 1 is a graph showing the Raman spectrum of Li ₂ ZrSO ₄ Cl ₄ having high ion conductivity, which is an example of the solid electrolyte according to the present embodiment (20 to 1000 cm ^-1 ). Fig. 2 is a graph showing an enlargement of the portion surrounded by the dotted line indicated by P1 in the Raman spectrum shown in Fig. 1 (50 to 500 cm ^-1 ).
A method 1 for evaluating the Raman spectroscopic characteristics of a solid electrolyte according to this embodiment will be described with reference to FIGS. 1 and 2. FIG.

In Figure 1, the spectrum in the area surrounded by the dotted line indicated by P1 is a spectrum derived from the vibrational energy of the metal (M)-halogen (X) bond. In the Raman spectrum detected by Raman spectroscopy, the heavier the M or X, the lower the wavenumber of the peak.
Fig. 8 in Non-Patent Document 2 shows that the peak shifts to the lower wavenumber side when X is changed from Cl to Br to I. Here, the number of peaks depends on the compound, but these peaks overlap to form two peaks, one of which is in the range of 200 to 450 cm ^-1 and the other is in the range of 80 to 200 cm ^-1 .
In the example of the Li-Sc-Cl based compound in Non-Patent Document 1, although Sc is lighter than Zr, compared with the above-mentioned example of the Li-Zr-Cl based compound, the peak at 200 to ⁴⁵⁰ cm is on the low wavenumber side, but the peak below ²⁰⁰ cm is on the high wavenumber side, and the peak is included in the range of this embodiment.
Even if M or X in a Li-M(metal)-X(halogen) compound is changed, the peak derived from the M--X bond is considered to be included in the range of this embodiment.

In the Raman spectrum (50 to 500 cm ⁻¹ ) of FIG. 2, there are two peaks, a peak indicated by the symbol A (hereinafter sometimes referred to as “peak A”) and a peak indicated by the symbol B (hereinafter sometimes referred to as “peak B”).

In this specification, the "peaks" (in FIG. 2, the character A denotes peak A, and the character B denotes peak B) are determined as follows.
A straight line that is parallel to the horizontal axis and longer than the range of wave numbers from 50 to 500 cm ^-1 is moved toward higher relative intensity while remaining parallel to the horizontal axis, and the point where the straight line first hits the Raman spectrum is called "origin 1A" (indicated by the symbol F1 in Figure 2). Origin 1A is the point where the relative intensity is the lowest in the range of wave numbers from 50 to 500 cm ^-1 . The straight line is tilted based (fixed) on this origin 1A.
Here, when origin 1A is at a wavenumber position of 350 cm ^-1 or more in the Raman spectrum, origin 1A is used as a reference (fixed), and the line is rotated left and the next point where it hits the Raman spectrum is called "origin 2A" (indicated by symbol F2 in FIG. 2). The line connecting origin 1A and origin 2A is called baseline A (indicated by symbol BL _A in FIG. 2), and the part between baseline A and the Raman spectrum is peak part A. Note that when determining origin 2A, if the line hits the Raman spectrum at a wavenumber position within a small range of about 30 cm ^-1 from the wavenumber of origin 1A, that point is not determined as origin 2A, and origin 2A is determined at the position beyond which the rise in intensity reaches its peak.
Here, in the Raman spectrum, when origin 1A is at a position of a wave number less than 350 cm ⁻¹ , the next point on the Raman spectrum that is reached by rotating the straight line clockwise from origin 1A is called origin 2A.
Next, a straight line parallel to the horizontal axis and longer than the range of wavenumbers 50 to 500 cm ⁻¹ is moved from high to low relative intensity while remaining parallel to the horizontal axis, and from the point where the straight line first hits the Raman spectrum on the low wavenumber side of peak A, it is moved further toward lower relative intensity, and the point just before the straight line first deviates from the Raman spectrum is taken as "origin 1B" (indicated by symbol F4 in FIG. 2). In the Raman spectrum, if origin 1B is at a wavenumber position of less than 150 cm ⁻¹ , the straight line is rotated left based on (fixed to) this origin 1B, and the point just before it deviates from the Raman spectrum is taken as "origin 2B" (indicated by symbol F3 in FIG. 2). The straight line between origin 1B and origin 2B is called baseline B (indicated by symbol BL _B in FIG. 2), and the part between baseline B and the Raman spectrum is peak B. When determining starting point 2B, if the straight line deviates from the Raman spectrum at a wavenumber position within a small range of about 30 cm ⁻¹ from the wavenumber of starting point 1B, that point is not determined as starting point 2B, and starting point 2B is determined at the position after the rising intensity reaches its peak.
Here, when origin 1B is at a position of a wave number of 150 cm ^-1 or more in the Raman spectrum, origin 1B is used as the reference and the point immediately before the line rotated right and next deviating from the Raman spectrum is called origin 2B.
The peak A and peak B thus determined are present in the range of 200 to 450 cm ⁻¹ and the range of 80 to 200 cm ⁻¹ , respectively, in the Raman spectrum of the solid electrolyte according to this embodiment.
The method for determining peak A and peak B based on the Raman spectrum of FIG. 2 has been described above, but peak A and peak B can also be determined for other Raman spectra in a similar manner.

In each of peak portion A and peak portion B, the peaks at the wavenumbers at which the relative intensity is maximum are referred to as the "strongest peaks." In Fig. 2, the apexes of the peaks indicated by symbols P _A and P _B are the strongest peaks in peak portion A and peak portion B, respectively.

In the solid electrolyte according to this embodiment, peak portion A has a peak width w _A at half the intensity h _A1 of the strongest peak P _A from baseline A (h _A1 +h _A2 ), and peak portion ^B has a peak width w _B at half the intensity h _B1 of the strongest peak P _B from baseline B (h _B1 ⁺ h _B2 ).
In the Li ₂ ZrSO ₄ Cl ₄ with high ion conductivity shown in Figure 2, the peak width w _A was 121.7 cm ^-1 and the peak width w _B was 85.7 cm ^-1 . In the Li ₂ ZrSO ₄ Cl ₄ without high ion conductivity, the peak width w _A was 53.6 cm ^-1 and the peak width w _B was 64.9 cm ^-1 .

In the solid electrolyte according to this embodiment, the peak width w _A is preferably 55 cm ⁻¹ or more and the peak width w _B is preferably 66 cm ⁻¹ or more, and _more preferably 80 cm ⁻¹ or more.

In the solid electrolyte according to this embodiment, it is preferable that the wave number of the strongest peak P 2 _B in the peak portion B is 140 cm ⁻¹ or less.
The Raman spectrum in the range of 80 to 200 cm ⁻¹ is a peak due to bending of the metal-halogen bond. While having a wide half-width, the position of this peak shifts to the lower wavenumber side, resulting in a metal-halogen bond with a wide energy distribution. This makes it easier for a conduction path for Li ⁺ ions to be formed, resulting in high ionic conductivity.

(Raman Spectroscopic Characteristics (Evaluation Method 2))
In the solid electrolyte according to this embodiment, when a straight line passing through a minimum point X and a second minimum point Y in a region of 400 to 1000 cm ⁻¹ in a Raman spectrum detected by Raman spectroscopy is defined as a baseline C, the intensities from the baseline C of the strongest peak P _A of the peak portion A and the strongest peak P _B of the peak portion B are defined as IA and IB, respectively, and IC is defined as an intensity at which the intensity from the baseline C is minimum between the peak portion A and the peak portion B, the relationship is 0<IC.
Due to the disturbance of the crystal structure, the distribution of the metal-halogen bond energy spreads, and the vibration mode at the lower limit of the region of peak A spreads toward the lower limit side, and the vibration mode at the upper limit of the region of peak B spreads toward the upper limit side. As a result, the distinction between the two peak regions becomes unclear, which increases the probability of Li ⁺ ion migration and results in high ionic conductivity.
The Raman spectroscopic characteristics obtained by evaluation method 2 will be described in detail below.

A method for evaluating the Raman spectroscopic characteristics of a solid electrolyte according to this embodiment will be described below with reference to FIGS. 3 and 4. FIG.
First, as shown in FIG. 3, a line passing through point X of the minimum relative intensity in the region of 400 to 1000 cm ⁻¹ and point Y of the next minimum relative intensity is defined as a baseline C.
Next, as shown in FIG. 4 , when the intensities from a baseline C of the strongest peak P _A of the peak portion A and the strongest peak P _B of the peak portion B are respectively designated as IA and IB, and the intensity at which the intensity from the baseline C between the peak portion A and the peak portion B is the smallest is designated as IC, 0<IC.

In the solid electrolyte according to this embodiment, it is preferable that the intensity IA of the strongest peak _PA in the peak portion A and the minimum intensity IC satisfy 0.2≦IC/IA≦0.6.
In the solid electrolyte according to this embodiment, the intensity IB of the strongest peak P _B in the peak portion B and the minimum intensity IC preferably satisfy 0.1≦IC/IB≦0.6.
In the solid electrolyte according to this embodiment, it is preferable that the intensity IA of the strongest peak _PA in the peak portion A and the intensity IB of the strongest peak _PB in the peak portion B satisfy IA<IB.

The solid electrolyte according to this embodiment preferably has peaks at 170±0.5 eV (where the chemical state of sulfur corresponds to _SO4 ) and 532±0.5 eV (where the chemical state of oxygen corresponds to _SO4 ) in a photoelectron spectrum measured by X-ray photoelectron spectroscopy (XPS).
The sulfur and oxygen in the solid electrolyte are tightly bonded to maintain the _SO4 structure and are present in the solid electrolyte material, which promotes an amorphous structure and makes it easier to form a conduction path for Li ⁺ ions, resulting in high ionic conductivity.

The solid electrolyte according to this embodiment preferably has peaks at 132.5±0.5 eV (where the chemical state of phosphorus corresponds to _PO4 ) and 531.5±0.5 eV (where the chemical state of oxygen corresponds to _PO4 ) in a photoelectron spectrum measured by X-ray photoelectron spectroscopy (XPS).
The sulfur and oxygen in the solid electrolyte are firmly bonded to maintain the _PO4 structure and are present in the solid electrolyte material, which promotes an amorphous structure and makes it easier to form a conductive path for Li ⁺ ions, resulting in high ionic conductivity.

"Solid electrolyte battery"
Fig. 5 is a schematic cross-sectional view of a solid electrolyte battery 100 according to this embodiment. The solid electrolyte battery 100 shown in Fig. 5 includes a power generating element 40 and an exterior body 50. The exterior body 50 covers the periphery of the power generating element 40. The power generating element 40 is connected to the outside through a pair of terminals 60, 62 that are connected to each other. Although a stacked type battery is shown in Fig. 1, a wound type battery may also be used. The solid electrolyte battery 100 is used, for example, in laminate batteries, square batteries, cylindrical batteries, coin batteries, button batteries, etc.

<Power generation element>
The power generating element 40 includes a solid electrolyte layer 10, a positive electrode 20, and a negative electrode 30. The power generating element 40 is charged or discharged by the exchange of ions between the positive electrode 20 and the negative electrode 30 via the solid electrolyte layer 10 and the exchange of electrons via an external circuit.

(Solid electrolyte layer)
The solid electrolyte layer 10 is a layer containing the solid electrolyte according to the present embodiment. The solid electrolyte layer 10 may be the solid electrolyte according to the present embodiment alone, or may be used together with a support such as a binder or a nonwoven fabric. The binder may be the same as that used for the electrodes.
The ratio of the binder to the solid electrolyte is preferably 10% or less by volume. The support such as a nonwoven fabric may be insulating like the resin, ceramics, or glass used in the binder, and preferably has an aperture ratio of 85% or more.
The solid electrolyte layer 10 is sandwiched between the positive electrode 20 and the negative electrode 30. The solid electrolyte layer 10 includes a solid electrolyte that can move ions by an externally applied voltage. For example, the solid electrolyte conducts lithium ions and inhibits the movement of electrons.

The solid electrolyte layer 10 is, for example, a halide-based solid electrolyte. The solid electrolyte layer 10 includes, for example, the above-mentioned solid electrolyte. If the positive electrode 20 or the negative electrode 30 includes the above-mentioned solid electrolyte, the solid electrolyte included in the solid electrolyte layer 10 does not have to be one of the above.

(Positive electrode)
5, the positive electrode 20 has a plate-shaped (foil-shaped) positive electrode current collector 22 and a positive electrode mixture layer 24. The positive electrode mixture layer 24 is in contact with at least one surface of the positive electrode current collector 22.

The positive electrode collector 22 may be made of any electronically conductive material that is resistant to oxidation during charging and is not easily corroded. The positive electrode collector 22 may be made of, for example, a metal such as aluminum, stainless steel, nickel, or titanium, or a conductive resin. The positive electrode collector 22 may be in the form of a powder, foil, punching, or expanded material.

The positive electrode mixture layer 24 contains a positive electrode active material, and optionally a solid electrolyte, a binder, and a conductive additive.

The positive electrode active material is not particularly limited as long as it is capable of reversibly absorbing and releasing lithium ions and inserting and removing them (intercalation and deintercalation), and any positive electrode active material used in known solid electrolyte batteries can be used. Examples of positive electrode active materials include lithium-containing metal oxides and lithium-containing metal phosphates.

Examples of lithium-containing metal oxides include lithium cobalt oxide ( _LiCoO2 ), lithium nickel oxide ( _LiNiO2 ), lithium manganese spinel ( _LiMn2O4 ), composite metal oxides represented by the general formula _{LiNixCoyMnzO2} (x _{+ y} + _z = ₁ ), lithium vanadium compounds ( _LiVOPO4 , _Li3V2 ( _PO4 ) ₃ ), olivine-type _LiMPO4 (wherein M represents at least one selected from Co, Ni, Mn, and Fe), _{and lithium titanate (Li4Ti5O12 )} .

The positive electrode active material may not contain lithium. Examples of such positive electrode active materials include non-lithium-containing metal oxides (MnO ₂ , V ₂ O ₅ , etc.), non-lithium-containing metal sulfides (MoS ₂ , etc.), and non-lithium-containing fluorides (FeF ₃ , VF ₃ , etc.). When using a positive electrode active material that does not contain lithium, the negative electrode is doped with lithium ions in advance, or a negative electrode containing lithium ions is used.

The solid electrolyte contained in the positive electrode 20 is, for example, the solid electrolyte described above. The solid electrolyte contained in the positive electrode 20 may be a halide-based solid electrolyte other than the solid electrolyte described above.

The content of the solid electrolyte in the positive electrode mixture layer 24 is not particularly limited, but is preferably 1% by mass to 50% by mass, and more preferably 5% by mass to 30% by mass, based on the total mass of the positive electrode active material, solid electrolyte, conductive additive, and binder.

The binder bonds the positive electrode active material, solid electrolyte, and conductive additive to each other in the positive electrode mixture layer 24, and also firmly bonds the positive electrode mixture layer 24 and the positive electrode current collector 22. The positive electrode mixture layer 24 preferably contains a binder. The binder preferably has oxidation resistance and good adhesiveness.

Binders used in the positive electrode mixture layer 24 include polyvinylidene fluoride (PVDF) or copolymers thereof, polytetrafluoroethylene (PTFE), polyamide (PA), polyimide (PI), polyamideimide (PAI), polybenzimidazole (PBI), polyethersulfone (PES), polyacrylic acid (PA) and copolymers thereof, metal ion crosslinked polyacrylic acid (PA) and copolymers thereof, polypropylene (PP) grafted with maleic anhydride, polyethylene (PE) grafted with maleic anhydride, or mixtures thereof. Among these, it is particularly preferable to use PVDF as the binder.

The binder content in the positive electrode mixture layer 24 is not particularly limited, but is preferably 1% by mass to 15% by mass, and more preferably 3% by mass to 5% by mass, based on the total mass of the positive electrode active material, solid electrolyte, conductive additive, and binder. If the amount of binder is too small, it tends not to be possible to form a positive electrode 20 with sufficient adhesive strength. Conversely, if the amount of binder is too large, it tends to be difficult to obtain sufficient volume or mass energy density, as typical binders are electrochemically inactive and do not contribute to the discharge capacity.

The conductive additive improves the electronic conductivity of the positive electrode mixture layer 24. Known conductive additives can be used. Examples of the conductive additive include carbon materials such as carbon black, graphite, carbon nanotubes, and graphene; metals such as aluminum, copper, nickel, stainless steel, iron, and amorphous metals; conductive oxides such as ITO; and mixtures of these. The conductive additive may be in the form of a powder or fiber.

The content of the conductive additive in the positive electrode mixture layer 24 is not particularly limited. When a conductive additive is added, the mass ratio of the conductive additive is preferably 0.5% by mass to 20% by mass, and more preferably 1% by mass to 5% by mass, based on the total mass of the positive electrode active material, solid electrolyte, conductive additive, and binder.

(Negative electrode)
5, the negative electrode 30 has a negative electrode current collector 32 and a negative electrode mixture layer 34. The negative electrode mixture layer 34 is in contact with the negative electrode current collector 32.

The negative electrode current collector 32 may have electronic conductivity. The negative electrode current collector 32 may be, for example, a metal such as copper, aluminum, nickel, stainless steel, or iron, or a conductive resin. The negative electrode current collector 32 may be in the form of a powder, foil, punching, or expanded.

The negative electrode mixture layer 34 contains a negative electrode active material, and if necessary, a solid electrolyte, a binder, and a conductive additive.

The negative electrode active material is not particularly limited as long as it can reversibly absorb and release lithium ions, and insert and remove lithium ions. The negative electrode active material may be any negative electrode active material used in known solid electrolyte batteries.

Examples of the negative electrode active material include carbon materials such as natural graphite, artificial graphite, mesocarbon microbeads, mesocarbon fiber (MCF), cokes, glassy carbon, and organic compound sintered bodies, metals that can be combined with lithium such as Si, SiO _x , Sn, and aluminum, alloys of these, composite materials of these metals and carbon materials, oxides such as lithium titanate (Li ₄ Ti ₅ O ₁₂ ) and SnO ₂ , and metallic lithium. Natural graphite is preferable as the negative electrode active material.

The solid electrolyte contained in the negative electrode 30 is, for example, the solid electrolyte described above. The solid electrolyte contained in the negative electrode 30 may be a halide-based solid electrolyte other than the solid electrolyte described above.

The binder and conductive additive contained in the negative electrode 30 are the same as the binder and conductive additive contained in the positive electrode 20.

<Exterior body>
The exterior body 50 houses the power generating element 40 therein. The exterior body 50 prevents moisture and the like from entering from the outside to the inside. As shown in Fig. 5, for example, the exterior body 50 has a metal foil 52 and a resin layer 54 laminated on each side of the metal foil 52. The exterior body 50 is a metal laminate film in which the metal foil 52 is coated with the resin layer 54 from both sides.

The metal foil 52 is, for example, an aluminum foil or a stainless steel foil. The resin layer 54 can be, for example, a resin film such as polypropylene. The materials constituting the resin layer 54 may be different on the inside and outside. For example, the outside material can be a polymer with a high melting point, such as polyethylene terephthalate (PET) or polyamide (PA), and the inside material can be polyethylene (PE) or polypropylene (PP).

<Terminals>
The terminals 60 and 62 are connected to the positive electrode 20 and the negative electrode 30, respectively. The terminal 60 connected to the positive electrode 20 is a positive electrode terminal, and the terminal 62 connected to the negative electrode 30 is a negative electrode terminal. The terminals 60 and 62 are responsible for electrical connection to the outside. The terminals 60 and 62 are made of a conductive material such as aluminum, nickel, or copper. The connection method may be welding or screwing. The terminals 60 and 62 are preferably protected with insulating tape to prevent short circuits.

[Method of manufacturing solid electrolyte battery]
Next, a method for manufacturing a solid electrolyte battery according to this embodiment will be described. First, a solid electrolyte is prepared. The solid electrolyte can be manufactured, for example, by mixing raw material powders containing predetermined elements at a predetermined molar ratio and causing a mechanochemical reaction. When carrying out the mechanochemical reaction, the unreacted raw materials are adjusted so as to remain in the solid electrolyte. Specifically, the unreacted components of the raw materials can be left by changing the rotation speed, revolution speed, synthesis time, and state of the raw material powder at the time of input of the planetary ball mill.

In order to improve the ionic conductivity of the solid electrolyte according to this embodiment, even with the same composition, the solid electrolyte is synthesized so that the crystallinity is low (promoting an amorphous structure). In this synthesis method, the synthesis of the raw material powder proceeds while suppressing excessive crystallinity. If such synthesis is possible, there are no limitations on the adjustment method, but it has been found that it is particularly important to cool immediately after the start of synthesis, shorten the synthesis time (the synthesis time that has been conventionally performed differs depending on the solid electrolyte, but the synthesis time is shorter than the conventional synthesis time for each solid electrolyte type), and adjust the dew point when the raw material powder is added and when the container is sealed.

If the raw material powder contains a halide raw material, the halide raw material is likely to evaporate when the temperature is raised. For this reason, halogen gas may be present in the atmosphere during sintering to compensate for the halogen. Also, if the raw material powder contains a halide raw material, it may be sintered by hot pressing using a highly airtight mold. In this case, the highly airtight mold can suppress the evaporation of the halide raw material due to sintering. By sintering in this way, a solid electrolyte in the form of a sintered body made of a compound having a specified composition is obtained.

Next, the positive electrode 20 is prepared. The positive electrode 20 is manufactured by applying a paste containing a positive electrode active material onto a positive electrode current collector 22 and drying it to form a positive electrode mixture layer 24. The above-mentioned solid electrolyte may be added to the paste containing the positive electrode active material.

Next, the negative electrode 30 is prepared. The negative electrode 30 is manufactured by applying a paste containing a negative electrode active material onto the negative electrode current collector 32 and drying it to form a negative electrode mixture layer 34. The above-mentioned solid electrolyte may be added to the paste containing the negative electrode active material.

The power generating element 40 can be produced, for example, by using a powder molding method. A guide with a hole is placed on top of the positive electrode 20, and the guide is filled with a solid electrolyte. The surface of the solid electrolyte is then smoothed, and the negative electrode 30 is placed on top of the solid electrolyte. This results in the solid electrolyte being sandwiched between the positive electrode 20 and the negative electrode 30. Pressure is then applied to the positive electrode 20 and the negative electrode 30 to pressure mold the solid electrolyte. By pressure molding, a laminate is obtained in which the positive electrode 20, solid electrolyte layer 10, and negative electrode 30 are stacked in this order.

Next, external terminals are welded to the positive electrode collector 22 of the positive electrode 20 and the negative electrode collector 32 of the negative electrode 30, which form the laminate, by a known method, to electrically connect the positive electrode collector 22 or the negative electrode collector 32 to the external terminal. After that, the laminate connected to the external terminal is housed in an exterior body 50, and the opening of the exterior body 50 is heat sealed to seal it. Through the above steps, the solid electrolyte battery 100 of this embodiment is obtained.

The solid electrolyte battery 100 according to this embodiment contains the above-mentioned solid electrolyte, so Li ions are smoothly conducted and the internal resistance is low.

The above describes the embodiments of the present invention in detail with reference to the drawings, but each configuration and their combinations in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications to the configurations of the present embodiments are possible without departing from the technical requirements of the present invention.

"Example 1"
(Preparation of solid electrolyte)
In a glove box with a dew point of about -75°C, zirconium chloride ( _ZrCl4 ) and _lithium sulfate ( _Li2SO4 ) were weighed out to a molar ratio of 1:8, and then placed in a zirconia sealed container for a planetary ball mill that had zirconia balls in it. Next, the sealed container was covered with a lid, the lid was screwed onto the container body, and the gap between the lid and the container was sealed with polyimide tape. The polyimide tape has the effect of blocking moisture. Next, the zirconia sealed container was set in the planetary ball mill. The rotation speed was set to 300 rpm, the revolution speed was set to 300 rpm, and the rotation direction and the revolution direction were set in the opposite directions. _A mechanochemical reaction was carried out for 2.5 hours to synthesize a solid electrolyte ( _Li4Zr0.25 ( _SO4 ) _2Cl ). The synthesis was carried out while cooling the zirconia closed vessel so that the temperature change of the lid was 10° C. or less one hour after the start of the synthesis.

The planetary ball mill is installed in a normal atmosphere (air). The zirconia sealed container for the planetary ball mill is screwed in place and further sealed with polyimide tape. When the zirconia sealed container is set in the planetary ball mill, it is firmly pressed into place. This means that even in a normal atmosphere, there is little chance of moisture entering the zirconia sealed container from the air.

<Measurement of Raman spectrum>
The Raman spectrum of the solid electrolyte of Example 1 was measured by Raman spectroscopy.
The measurement conditions for the Raman spectrum were laser wavelength: 532 nm, slit width: 100×1000 μm, aperture: 40 μm, exposure time: 60 sec, and accumulation: 2 times.
Using evaluation method 1, peak A in the range of 200 to 450 cm ⁻¹ and peak B in the range of 80 to 200 cm ⁻¹ were determined, and the strongest peak and half width of each peak were measured.
In addition, using evaluation method 2, a baseline C was determined, and the intensities IA and IB of the strongest peak P _A in peak portion A and the strongest peak P _B in peak portion B from the baseline C, as well as the intensity IC at which the intensity from the baseline C between peak portion A and peak portion B is the smallest, were measured.

<XPS Measurement>
In addition, the photoelectron spectrum of the solid electrolyte of Example 1 was measured by X-ray photoelectron spectroscopy. Sampling was performed in a glove box with a dew point of about -70°C in which argon gas was circulating, and the sample was transported to an XPS measurement device in a state not exposed to the atmosphere. The photoelectron spectrum was measured using a Quantera 2 manufactured by PHI Corporation. As a result, peaks were confirmed at 170±0.5 eV and 532±0.5 eV in the prepared solid electrolyte.

<Measurement of ionic conductivity>
Next, in a glove box with argon gas circulating at a dew point of about -70°C, the obtained solid electrolyte powder was filled into a pressure molding die and pressure molded with a load of about 30 kN to prepare a measurement cell for ion conductivity.

The pressure molding die consisted of a 10 mm diameter cylinder made of PEEK (polyether ether ketone), and upper and lower punches made of SKD11 material with a diameter of 9.99 mm.

　After that, a stainless steel disk and a Teflon (registered trademark) disk, both 50 mm in diameter and 5 mm thick and with four screw holes, were prepared, and the pressure molding die was set up as follows: Stainless steel disk / Teflon (registered trademark) disk / pressure molding die / Teflon (registered trademark) disk / stainless steel disk. The four screws were then tightened with a torque of approximately 3 N·m. Screws were also inserted into the screw holes on the sides of the upper and lower punches to serve as external connection terminals.

The external connection terminal was connected to a potentiostat (VersaSTAT3 manufactured by Princeton Applied Research) equipped with a frequency response analyzer, and the ionic conductivity was measured using an impedance measurement method. Measurement was performed at a measurement frequency range of 1 MHz to 0.1 Hz, an amplitude of 10 mV, and a temperature of 25° C. The ionic conductivity of the solid electrolyte of Example 1 was 1.1×10 ⁻³ S/cm.

The composition, molar ratio and measurement results of each raw material are summarized in Tables 1, 2 and 7 below.
In Tables 7 and 8, the width of the peak A (B) at half the intensity of the strongest peak P _A (P _B ) from the baseline A (B) is described as "half width".

"Examples 2 to 8"
In Examples 2 to 8, solid electrolytes were synthesized in the same manner as in Example 1, except that the materials and/or molar ratios of the raw material powders and the synthesis time were changed. In Examples 2 to 8, the physical properties of the solid electrolytes were measured in the same manner as in Example 1. The compositions, molar ratios, and measurement results of each raw material are summarized in Tables 1, 2, and 7 below.
6A shows the Raman spectrum of Example 4, the Raman spectroscopic characteristics of which were evaluated by Evaluation Method 1. FIG. 6B shows the Raman spectrum of Example 4, the Raman spectroscopic characteristics of which were evaluated by Evaluation Method 2.

"Example 9"
In a glove box with a dew point of about -75°C, zirconium sulfate ( _ZrSO4 ), zirconium chloride ( _ZrCl4 ), and _lithium sulfate ( _Li2SO4 ) were weighed out in a molar ratio of 0.5:1:1, and were then put into a zirconia sealed container for a planetary ball mill that had zirconia balls in it beforehand. Next, the sealed container was covered with a lid, the lid was screwed onto the container body, and the gap between the lid and the container was sealed with polyimide tape. The polyimide tape has the effect of blocking moisture. Next, the zirconia sealed container was set in the planetary ball mill. The rotation speed was set to 300 rpm, the revolution speed was set to 300 rpm, and the rotation direction and the revolution direction were set in the opposite directions, and a mechanochemical reaction was carried out for 5 hours to synthesize _a solid electrolyte ( _Li2Zr1.5 ( _SO4 ) _2Cl ).
In detail, when the raw material powder was charged into the zirconia sealed container, _{Li2SO4 was} pulverized for 1 hour before mixing using the same planetary ball mill as described above at a rotation speed of 300 rpm. Then, _ZrCl4 was added and mixed and pulverized for another hour at a rotation speed of 200 rpm. Next, the remaining raw material ( _ZrSO4 in Example 9) was added to complete the charging.
The synthesis was carried out while cooling the zirconia closed vessel so that the temperature change of the lid was 10° C. or less one hour after the start of the synthesis.
In Example 9, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The compositions and molar ratios of the raw materials and the measurement results are summarized in Tables 1, 2, and 7 below.

"Example 10"
In Example 10, a solid electrolyte was synthesized in the same manner as in Example 9, except that zirconium sulfate (ZrSO ₄ ), zirconium chloride (ZrCl ₄ ), and lithium sulfate (Li ₂ SO ₄ ) were weighed out in a molar ratio of 0.4:1:1.5.
In Example 10, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The compositions and molar ratios of the raw materials and the measurement results are summarized in Tables 1, 2, and 7 below.

"Examples 11 to 21"
In Examples 11 to 21, solid electrolytes were synthesized in the same manner as in Example 9, except that the materials and molar ratios of the raw material powders were changed. In Examples 11 to 21, the physical properties of the solid electrolytes were measured in the same manner as in Example 9. The measurement results are summarized in Tables 1, 2, 7, and 8 below.

"Example 22"
In a glove box with a dew point of about -75°C, lithium oxide (Li ₂ O) and zirconium chloride (ZrCl ₄ ) were weighed out to a molar ratio of 10:1, and then placed in a zirconia sealed container for a planetary ball mill that already contained zirconia balls. Next, the sealed container was covered with a lid, the lid was screwed onto the container body, and the gap between the lid and the container was sealed with polyimide tape. The polyimide tape has the effect of blocking moisture.
Next, the zirconia sealed container was set in a planetary ball mill. The rotation speed was set to 300 rpm, the revolution speed was set to 300 rpm, and the rotation direction and the revolution direction were set to opposite directions to perform a mechanochemical reaction for 4 hours to synthesize a solid electrolyte (Li ₁₀ ZrO ₅ Cl ₄ ).
In detail, when the raw material powders were charged into a zirconia sealed container, Li ₂ O was ground for 1 hour before mixing using the same planetary ball mill as described above at a rotation speed of 300 rpm. Next, the remaining raw materials (ZrCl ₄ in Example 22) were added.
The synthesis was carried out while cooling the zirconia closed vessel so that the temperature change of the lid was 10° C. or less one hour after the start of the synthesis.
In Example 22, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The compositions and molar ratios of the raw materials and the measurement results are summarized in Tables 3, 4, and 8 below.

"Examples 23 to 26"
In Example 23, a solid electrolyte was synthesized in the same manner as in Example 22, except that the molar ratio of the raw material powders was changed and the synthesis time was set to 6 hours.
In Example 24, a solid electrolyte was synthesized in the same manner as in Example 22, except that the molar ratio of the raw material powders was changed and the synthesis time was set to 24 hours.
In Example 25, a solid electrolyte was synthesized in the same manner as in Example 22, except that the molar ratio of the raw material powders was changed and the synthesis time was set to 48 hours.
In Example 26, a solid electrolyte was synthesized in the same manner as in Example 22, except that the molar ratio of the raw material powders was changed and the synthesis time was set to 72 hours.
In Examples 23 to 26, the physical properties of the solid electrolyte were measured in the same manner as in Example 22. The compositions and molar ratios of the raw materials and the measurement results are summarized in Tables 3, 4, and 8 below.
7A shows the Raman spectrum of Example 25, the Raman spectroscopic characteristics of which were evaluated by Evaluation Method 1. FIG. 7B shows the Raman spectrum of Example 25, the Raman spectroscopic characteristics of which were evaluated by Evaluation Method 2.

"Examples 27 to 30"
In Examples 27 to 30, solid electrolytes were synthesized in the same manner as in Example 22, except that the materials and molar ratios of the raw material powders were changed. In Examples 23 to 30, the physical properties of the solid electrolytes were measured in the same manner as in Example 22. The compositions, molar ratios, and measurement results of each raw material are summarized in Tables 3, 4, and 8 below.

"Example 31"
In Example 31, a solid electrolyte was synthesized in the same manner as in Example 1, except that the raw material powders were charged and the container was sealed in a dry room with a dew point of -40°C. In Example 31, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are summarized in Tables 3, 4, and 8 below.

"Example 32"
In Example 32, a solid electrolyte was synthesized in the same manner as in Example 1, except that the raw material powders were charged and the container was sealed in a dry room with a dew point of -60°C. In Example 32, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are summarized in Tables 3, 4, and 8 below.

"Example 33"
In Example 33, a solid electrolyte was synthesized in the same manner as in Example 1, except that the molar ratio of the raw material powders was changed. In Example 33, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are summarized in Tables 3, 4, and 8 below.

"Comparative Example 1"
In Comparative Example 1, a solid electrolyte was synthesized in the same manner as in Example 1, except that the materials and molar ratios of the raw material powders were changed, and the zirconia container was not cooled for 1 hour after the start of synthesis, and the synthesis time was 24 hours. The temperature change of the lid of the zirconia sealed container reached 20° C. or more 1 hour after the start of synthesis. In Comparative Example 1, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The composition, molar ratios, and measurement results of each raw material are summarized in Tables 5, 6, and 9 below.
FIG. 8 shows the Raman spectrum of Comparative Example 1, in which the Raman spectroscopic characteristics were evaluated by Evaluation Method 1.

"Comparative Example 2"
In Comparative Example 2, a solid electrolyte was synthesized in the same manner as in Example 1, except that the molar ratio of the raw material powders was changed, and the synthesis time was 24 hours without cooling the zirconia container 1 hour after the start of synthesis. The temperature change of the lid of the zirconia sealed container was 20° C. or more 1 hour after the start of synthesis. In Comparative Example 2, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are summarized in Tables 5, 6, and 9 below.
FIG. 9 shows the Raman spectrum of Comparative Example 2, in which the Raman spectroscopic characteristics were evaluated by Evaluation Method 1.

"Comparative Example 3"
In Comparative Example 3, the raw material powders were charged and the container was sealed in a dry room with a dew point of -20°C, and the solid electrolyte was synthesized in the same manner as in Example 1, except that the synthesis time was 5.5 hours. In Comparative Example 3, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are summarized in Tables 5, 6, and 9 below.

"Comparative Example 4"
In Comparative Example 4, a solid electrolyte was synthesized in the same manner as in Example 4, except that the zirconia vessel was not cooled for 1 hour after the start of synthesis. In Comparative Example 4, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are summarized in Tables 5, 6, and 9 below.

"Comparative Example 5"
In Comparative Example 5, a solid electrolyte was synthesized in the same manner as in Example 4, except that the synthesis time was 24 hours. In Comparative Example 5, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The compositions, molar ratios, and measurement results of the raw materials are summarized in Tables 5, 6, and 9 below.

"Comparative Example 6"
In Comparative Example 6, a solid electrolyte was synthesized in the same manner as in Example 17, except that the zirconia vessel was not cooled for 1 hour after the start of synthesis. In Comparative Example 6, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are summarized in Tables 5, 6, and 9 below.

"Comparative Example 7"
In Comparative Example 7, a solid electrolyte was synthesized in the same manner as in Example 18, except that the synthesis time was 24 hours. In Comparative Example 7, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The compositions, molar ratios, and measurement results of the raw materials are summarized in Tables 5, 6, and 9 below.

"Comparative Example 8"
In Comparative Example 8, a solid electrolyte was synthesized in the same manner as in Example 23, except that the synthesis time was 24 hours. In Comparative Example 8, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The compositions, molar ratios, and measurement results of the raw materials are summarized in Tables 5, 6, and 9 below.

"Comparative Example 9"
In Comparative Example 9, a solid electrolyte was synthesized in the same manner as in Example 24, except that the synthesis time was 48 hours. In Comparative Example 9, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The compositions, molar ratios, and measurement results of the raw materials are summarized in Tables 5, 6, and 9 below.

"Comparative Example 10"
In Comparative Example 10, a solid electrolyte was synthesized in the same manner as in Example 25, except that the zirconia container was not cooled for 1 hour after the start of synthesis. In Comparative Example 10, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are summarized in Tables 5, 6, and 9 below.

"Comparative Example 11"
In Comparative Example 11, a solid electrolyte was synthesized in the same manner as in Example 26, except that the zirconia container was not cooled for 1 hour after the start of synthesis. In Comparative Example 11, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The compositions, molar ratios, and measurement results of the raw materials are summarized in Tables 5, 6, and 9 below.

"Comparative Example 12"
In Comparative Example 12, a solid electrolyte was synthesized in the same manner as in Example 27, except that the synthesis time was 96 hours. In Comparative Example 12, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The compositions, molar ratios, and measurement results of the raw materials are summarized in Tables 5, 6, and 9 below.

"Comparative Example 13"
In Comparative Example 13, a solid electrolyte was synthesized in the same manner as in Example 33, except that the synthesis time was 72 hours. In Comparative Example 13, the physical properties of the solid electrolyte were measured in the same manner as in Example 1. The compositions, molar ratios, and measurement results of the raw materials are summarized in Tables 5, 6, and 9 below.

(Fabrication of all-solid-state batteries)
The all-solid-state battery was fabricated in a glove box with a dew point of about -70°C. The all-solid-state battery was fabricated using a pellet fabrication jig. The pellet fabrication jig had a PEEK (polyether ether ketone) holder with an inner diameter of 10 mm, and an upper punch and a lower punch with a diameter of 9.99 mm. The material of the upper and lower punches was die steel (SKD11 material).

A lower punch was inserted into the PEEK holder of the pellet making jig, and 50 mg of solid electrolyte was placed on top of the lower punch. The resin holder was then vibrated to smooth the surface of the solid electrolyte. An upper punch was then inserted on top of the solid electrolyte, and pressed with a press machine under a load of approximately 4 kN.

Next, the lower punch was removed, and 10 mg of the negative electrode mixture was placed on the solid electrolyte. Next, the PEEK holder was vibrated to level the surface of the negative electrode mixture. Next, the lower punch was inserted on the negative electrode mixture, and pressed with a press machine under a load of 3 kN. The negative electrode mixture was composed of a negative electrode active material and the above-mentioned solid electrolyte, and lithium titanate (LTO) with an average particle size of 6.0 μm was used as the negative electrode active material. Next, the upper punch was removed, and 10 mg of the positive electrode mixture was placed on the solid electrolyte layer. Next, the PEEK holder was vibrated to level the surface of the positive electrode mixture. Next, the upper punch was inserted on the positive electrode mixture, and pressed with a load of 3 kN using a press machine. The positive electrode mixture was composed of a positive electrode active material, carbon as a conductive assistant, and the above-mentioned solid electrolyte, and lithium cobalt oxide (LCO) with an average particle size of 7.5 μm was used as the positive electrode active material. In this way, an all-solid-state battery was produced in which the negative electrode mixture layer, the solid electrolyte layer, and the positive electrode mixture layer were stacked in that order.

Furthermore, two stainless steel plates with a diameter of 50 mm and a thickness of 5 mm and two Bakelite (registered trademark) plates with a diameter of 50 mm and a thickness of 2 mm were prepared. Next, four holes for passing screws were made in each of the two stainless steel plates and the two Bakelite (registered trademark) plates. The screw holes were made in positions where the two stainless steel plates and the two Bakelite (registered trademark) plates overlap in a planar view when the electrochemical cell and the two stainless steel plates and the two Bakelite (registered trademark) plates are stacked, but do not overlap in a planar view with the electrochemical cell.

　Then, a stainless steel plate, a Bakelite (registered trademark) plate, an all-solid-state battery, a Bakelite (registered trademark) plate, and a stainless steel plate were stacked in this order, and screws were inserted into the screw holes and tightened with a torque of 1 N·m. In this way, an all-solid-state battery was obtained in which the upper and lower punches of the electrochemical cell were insulated by the Bakelite (registered trademark) plate. Next, the all-solid-state battery was left to stand in a thermostatic chamber at 25°C for 48 hours to stabilize the open circuit voltage.

The rate characteristics were evaluated using the fabricated all-solid-state battery. The rate characteristics were evaluated from the ratio of the discharge capacity when discharged at a discharge rate of 1C to the discharge capacity at a discharge rate of 0.1C (0.1C/1C rate characteristics). The all-solid-state battery was placed in an environment of 25°C and constant current charged (CC charging) at a constant current of 0.1C rate until the battery voltage reached 2.7V. After reaching 2.7V, the battery was charged until the current reached 0.05C (CV charging). After that, the battery was discharged at a constant current of 0.1C rate until the battery voltage reached 1.5V (CC discharging), and the discharge capacity at 0.1C was measured. The all-solid-state battery was then charged again under the above conditions and discharged at a discharge rate of 1C until the battery voltage reached 1.5V, and the discharge capacity at 1C was measured. The measurement results are summarized in Tables 7 to 9.

Example 4, Comparative Example 2, Comparative Example 4, and Comparative Example 5 have the same composition, but the conditions of the synthesis step are different. In Example 4, the zirconia container was cooled 1 hour after the start of synthesis, and the synthesis time was 5.5 hours. In contrast, in Comparative Example 2, the zirconia container was not cooled 1 hour after the start of synthesis, and the synthesis time was 24 hours, which was longer than that of Example 4. In Comparative Example 4, like Comparative Example 2, the zirconia container was not cooled 1 hour after the start of synthesis, but the synthesis time was 5.5 hours, which was the same as that of Example 4. In Comparative Example 5, like Example 4, the zirconia container was cooled 1 hour after the start of synthesis, but the synthesis time was 24 hours, which was longer than that of Example 4.
Depending on the difference in the conditions of this synthesis process, the ionic conductivities of Example 4, Comparative Example 2, Comparative Example 4, and Comparative Example 5 were 2.3×10 ⁻³ [S/cm], 4.0×10 ⁻⁴ [S/cm], 8.9×10 ⁻⁴ [S/cm], and 6.3×10 ⁻⁴ [S/cm], respectively. Furthermore, depending on the magnitude of this ionic conductivity, the rate characteristics of Example 4, Comparative Example 2, Comparative Example 4, and Comparative Example 5 were 80%, 30%, 54%, and 43%, respectively.
As described above, even with the same composition, the ionic conductivity could be improved by adjusting the conditions of the synthesis process, and as a result, the rate characteristics could also be improved.
In Example 4, cooling was performed immediately after the start of synthesis, and the length of the synthesis time was optimized. In Comparative Example 2, cooling was not performed immediately after the start of synthesis, and the length of the synthesis time was not optimized. The ionic conductivity of Example 4 was 5.8 times that of Comparative Example 2. In Comparative Example 4, the length of the synthesis time was optimized, but cooling was not performed immediately after the start of synthesis. The ionic conductivity of Example 4 was 2.6 times that of Comparative Example 4. In Comparative Example 5, cooling was performed immediately after the start of synthesis, but the length of the synthesis time was not optimized. The ionic conductivity of Example 4 was 3.7 times that of Comparative Example 5.

Example 17 and Comparative Example 6 have the same composition, but different synthesis step conditions. In Example 17, the zirconia vessel was cooled for 1 hour after the start of synthesis. In contrast, in Comparative Example 6, the zirconia vessel was not cooled for 1 hour after the start of synthesis.
Depending on the difference in the conditions of this synthesis process, the ionic conductivities of Example 17 and Comparative Example 6 were 2.5×10 ⁻³ [S/cm] and 9.2×10 ⁻⁴ [S/cm], respectively. Also, depending on the magnitude of this ionic conductivity, the rate characteristics of Example 17 and Comparative Example 6 were 82% and 58%, respectively.
As described above, even with the same composition, the ionic conductivity could be improved by adjusting the conditions of the synthesis process, and as a result, the rate characteristics could also be improved.
The ionic conductivity of Example 17, in which cooling was performed immediately after the start of synthesis, was 2.7 times that of Comparative Example 6, in which cooling was not performed immediately after the start of synthesis.

Example 18 and Comparative Example 7 have the same composition, but the conditions of the synthesis process are different. The synthesis time in Example 18 was 5 hours, whereas the synthesis time in Comparative Example 7 was 24 hours.
Depending on the difference in the conditions of this synthesis process, the ionic conductivities of Example 18 and Comparative Example 7 were 2.7×10 ⁻³ [S/cm] and 9.5×10 ⁻⁴ [S/cm], respectively. Also, depending on the magnitude of this ionic conductivity, the rate characteristics of Example 18 and Comparative Example 7 were 84% and 62%, respectively.
As described above, even with the same composition, the ionic conductivity could be improved by adjusting the conditions of the synthesis process, and as a result, the rate characteristics could also be improved.
The ionic conductivity of Example 18, in which the synthesis time length was optimized, was 2.8 times that of Comparative Example 7, in which the synthesis time length was not optimized.

Example 23 and Comparative Example 8 have the same composition, but the conditions of the synthesis process are different. The synthesis time in Example 23 was 4 hours, whereas the synthesis time in Comparative Example 8 was 24 hours.
Depending on the difference in the conditions of this synthesis process, the ionic conductivities of Example 23 and Comparative Example 8 were 9.5×10 ⁻⁴ [S/cm] and 5.6×10 ⁻⁴ [S/cm], respectively. Also, depending on the magnitude of this ionic conductivity, the rate characteristics of Example 23 and Comparative Example 8 were 69% and 39%, respectively.
As described above, even with the same composition, the ionic conductivity could be improved by adjusting the conditions of the synthesis process, and as a result, the rate characteristics could also be improved.
The ionic conductivity of Example 23, in which the length of the synthesis time was optimized, was 3.6 times that of Comparative Example 8, in which the length of the synthesis time was not optimized.

Example 24 and Comparative Example 9 have the same composition, but the conditions of the synthesis process are different. The synthesis time in Example 24 was 4 hours, whereas the synthesis time in Comparative Example 9 was 24 hours.
Depending on the difference in the conditions of this synthesis process, the ionic conductivities of Example 24 and Comparative Example 9 were 2.6×10 ⁻³ [S/cm] and 7.7×10 ⁻⁴ [S/cm], respectively. Also, depending on the magnitude of this ionic conductivity, the rate characteristics of Example 24 and Comparative Example 9 were 83% and 47%, respectively.
As described above, even with the same composition, the ionic conductivity could be improved by adjusting the conditions of the synthesis process, and as a result, the rate characteristics could also be improved.
The ionic conductivity of Example 24, in which the synthesis time length was optimized, was 3.4 times that of Comparative Example 9, in which the synthesis time length was not optimized.

Example 25 and Comparative Example 10 have the same composition, but different synthesis step conditions. In Example 25, the zirconia vessel was cooled for 1 hour after the start of synthesis. In contrast, in Comparative Example 10, the zirconia vessel was not cooled for 1 hour after the start of synthesis.
Depending on the difference in the conditions of this synthesis process, the ionic conductivities of Example 25 and Comparative Example 10 were 3.2×10 ⁻³ [S/cm] and 9.8×10 ⁻⁴ [S/cm], respectively. Also, depending on the magnitude of this ionic conductivity, the rate characteristics of Example 25 and Comparative Example 10 were 86% and 67%, respectively.
As described above, even with the same composition, the ionic conductivity could be improved by adjusting the conditions of the synthesis process, and as a result, the rate characteristics could also be improved.
The ionic conductivity of Example 25, in which cooling was performed immediately after the start of synthesis, was 3.3 times that of Comparative Example 10, in which cooling was not performed immediately after the start of synthesis.

Example 26 and Comparative Example 11 have the same composition, but different synthesis step conditions. In Example 26, the zirconia vessel was cooled for 1 hour after the start of synthesis. In contrast, in Comparative Example 11, the zirconia vessel was not cooled for 1 hour after the start of synthesis.
Depending on the difference in the conditions of this synthesis process, the ionic conductivities of Example 26 and Comparative Example 11 were 2.3×10 ⁻³ [S/cm] and 8.2×10 ⁻⁴ [S/cm], respectively. Also, depending on the magnitude of this ionic conductivity, the rate characteristics of Example 26 and Comparative Example 11 were 80% and 55%, respectively.
As described above, even with the same composition, the ionic conductivity could be improved by adjusting the conditions of the synthesis process, and as a result, the rate characteristics could also be improved.
The ionic conductivity of Example 26, in which cooling was performed immediately after the start of synthesis, was 2.8 times that of Comparative Example 11, in which cooling was not performed immediately after the start of synthesis.

Example 27 and Comparative Example 12 have the same composition, but the conditions of the synthesis process are different. The synthesis time in Example 27 was 48 hours, whereas the synthesis time in Comparative Example 12 was 96 hours.
Depending on the difference in the conditions of this synthesis process, the ionic conductivities of Example 27 and Comparative Example 12 were 2.5×10 ⁻³ [S/cm] and 5.8×10 ⁻⁴ [S/cm], respectively. Also, depending on the magnitude of this ionic conductivity, the rate characteristics of Example 27 and Comparative Example 12 were 82% and 49%, respectively.
As described above, even with the same composition, the ionic conductivity could be improved by adjusting the conditions of the synthesis process, and as a result, the rate characteristics could also be improved.
The ionic conductivity of Example 27, in which the length of the synthesis time was optimized, was 4.3 times that of Comparative Example 12, in which the length of the synthesis time was not optimized.

Example 33 and Comparative Example 13 have the same composition, but the conditions of the synthesis process are different. The synthesis time of Example 33 was 48 hours, whereas the synthesis time of Comparative Example 13 was 72 hours.
Depending on the difference in the conditions of this synthesis process, the ionic conductivities of Example 33 and Comparative Example 13 were 2.5×10 ⁻³ [S/cm] and 4.9×10 ⁻⁴ [S/cm], respectively. Also, depending on the magnitude of this ionic conductivity, the rate characteristics of Example 33 and Comparative Example 13 were 82% and 49%, respectively.
As described above, even with the same composition, the ionic conductivity could be improved by adjusting the conditions of the synthesis process, and as a result, the rate characteristics could also be improved.
The ionic conductivity of Example 33, in which the length of the synthesis time was optimized, was 4.3 times that of Comparative Example 13, in which the length of the synthesis time was not optimized.

The solid electrolyte of this embodiment can be suitably applied to solid electrolyte batteries that serve as power sources for electronic devices.

10...solid electrolyte layer 20...positive electrode 22...positive electrode current collector 24...positive electrode mixture layer 30...negative electrode 32...negative electrode current collector 34...negative electrode mixture layer 40...power generating element 50...exterior body 52...metal foil 54...resin layers 60, 62...terminal 100...solid electrolyte battery

Claims (13)

The compound includes a compound represented by the following formula (1):
A solid electrolyte having, in a Raman spectrum detected by Raman spectroscopy, one peak each in a range of 200 to 450 cm ^-1 and a range of 80 to 200 cm ^-1 , wherein, when the peak in the range of 200 to 450 cm ^-1 is designated as peak A, a straight line connecting starting point 1A and starting point 2A of peak A is designated as baseline A, the peak in the range of 80 to 200 cm ^-1 is designated as peak B, and a straight line connecting starting point 1B and starting point 2B of peak B is designated as baseline B, the peak width at half the intensity of the strongest peak P _A from baseline A of peak A is 55 cm ^-1 or more, and the peak width at half the intensity of the strongest peak P _B from baseline B of peak B is 55 cm ^-1 or more;
Li _a A _b E _c J _e X _f H _h ... (1)
(In formula (1), A is at least one element selected from alkali metals other than Li and alkaline earth metals, E is at least one element selected from the group consisting of Al, Ga, In, Sc, Y, Ti, Zr, Hf, and lanthanoids, J is at least one group selected from the group consisting of anions, X is at least one element selected from the group consisting of F, Cl, Br, and I, and 0.5≦a<6, 0≦b<6, 0<c<2, 0<e≦6, 0<f≦6.1, and 0≦h≦0.2.) 2. The solid electrolyte according to claim 1, wherein the peak width of the peak portion B is 80 cm ⁻¹ or more. 2. The solid electrolyte according to claim 1, wherein the wave number at the strongest peak in the peak portion B is 140 cm ⁻¹ or less. In the Raman spectrum,
2. The solid electrolyte according to claim 1, wherein a straight line passing through a point X of the minimum value and a point Y of the next smallest minimum value in a region of 400 to 1000 cm ⁻¹ is defined as a baseline C, the intensities from the baseline C of the strongest peak P _A of the peak portion A and the strongest peak P _B of the peak portion B are defined as IA and IB, respectively, and an intensity at which the intensity from the baseline C is minimum between the peak portion A and the peak portion B is defined as IC, where 0<IC. The solid electrolyte according to claim 4 , wherein the intensity IA of the strongest peak P _A in the peak portion A and the intensity IC satisfy 0.2≦IC/IA≦0.6. The solid electrolyte according to claim 4 , wherein the intensity IB and the intensity IC of the strongest peak P _B in the peak portion B satisfy 0.1≦IC/IB≦0.6. The solid electrolyte according to claim 4 , wherein an intensity IA of the strongest peak _PA in the peak portion A and an intensity IB of the strongest peak _PB in the peak portion B satisfy IA<IB. The anion is OH, _BO2 , BO3, BO4, _B3O6 , _B4O7 , CO3, _NO3 , _AlO2 , _{SiO3 , SiO4, Si2O7, Si3O9, Si4O11, Si6O18 , PO3 , PO4 , P2O7 , P3O10 , SO3 , SO4 , SO5 , S2O3 , S2O4 , S2O5, S2O6 , S2O7 , S2O8 , BF4 , PF6 , BOB , ( COO ) 2 , N} , _{AlCl4 , CF3SO3} , _CH At least one group selected from the group consisting of _3COO , CF ₃ COO, OOC-(CH ₂ ) ₂ -COO, OOC-CH ₂ -COO, OOC-CH(OH)-CH(OH)-COO, OOC-CH(OH)-CH ₂ -COO, C ₆ H ₅ SO ₃ , OOC-CH═CH-COO, C(OH)(CH ₂ COOH) ₂ COO, AsO ₄ , BiO ₄ , CrO ₄ , MnO ₄ , PtF ₆ , PtCl ₆ , PtBr ₆ , PtI ₆ , SbO ₄ , SeO ₄ , TeO ₄ , HCOO, CH ₃ COO, and O (BOB is bis(oxalato borate, OOC-(CH ₂ ) ₂ -COO). 2. The solid electrolyte of claim 1, wherein -COO is an anion of succinic acid, OOC-CH ₂ -COO is an anion of malonic acid, OOC-CH(OH)-CH(OH)-COO is an anion of tartaric acid, OOC-CH(OH)-CH ₂ -COO is an anion of malic acid, C ₆ H ₅ SO ₃ is an anion of benzenesulfonic acid, OOC-CH=CH-COO (trans form) is an anion of fumaric acid, OOC-CH=CH-COO (cis form) is an anion of maleic acid, and C(OH)(CH ₂ COOH) ₂ COO is an anion of citric acid. 2. The solid electrolyte according to claim 1, having peaks at 170±0.5 eV (wherein the chemical state of sulfur corresponds to _SO4 ) and 532±0.5 eV (wherein the chemical state of oxygen corresponds to _SO4 ) in a photoelectron spectrum measured by X-ray photoelectron spectroscopy (XPS). 2. The solid electrolyte according to claim 1, having peaks at 132.5±0.5 eV (wherein the chemical state of phosphorus corresponds to _PO4 ) and 531.5±0.5 eV (wherein the chemical state of oxygen corresponds to _PO4 ) in a photoelectron spectrum measured by X-ray photoelectron spectroscopy (XPS). A solid electrolyte layer comprising the solid electrolyte according to any one of claims 1 to 10. A solid electrolyte battery comprising a solid electrolyte layer, a positive electrode, and a negative electrode, at least one of the positive electrode and the negative electrode containing the solid electrolyte according to any one of claims 1 to 10. A solid electrolyte battery comprising the solid electrolyte layer according to claim 11, a positive electrode, and a negative electrode.

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