JP2023021918A - Paste, solid electrolyte layer or electrode mixture layer, and solid-state battery - Google Patents

Abstract

To provide: a highly stable paste containing an organic solvent capable of restraining formation of lithium halide due to decomposition of halide solid electrolyte; a solid electrolyte layer or electrode mixture layer as a coating layer of the paste; and a solid-state battery having the solid electrolyte layer or electrode mixture layer.SOLUTION: A paste contains a halide solid electrolyte and an organic solvent. The halide solid electrolyte contains a halide composed of Li, M, and X (where M is at least one selected from the group consisting of metallic and semi-metallic elements other than Li, and X is at least one selected from the group consisting of F, Cl, Br, and I). The organic solvent contains at least one selected from aliphatic hydrocarbon, cyclic organic compound, chain ether having two long chain hydrocarbon groups having at least 4 carbons, and cyclic ether.SELECTED DRAWING: Figure 2

Description

The present invention relates to pastes, solid electrolyte layers or electrode mixture layers, and solid batteries.

In recent years, the demand for lithium-ion secondary batteries has increased as a power source for electric vehicles, hybrid vehicles, and the like. From the viewpoint of simplifying the system for ensuring safety, flame-retardant solid electrolytes have been actively developed as electrolytes used in these batteries.
As solid electrolytes, oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, and the like are known. When these solid electrolytes are used in a lithium ion secondary battery to form a solid battery, conventionally, it has generally been produced by press-molding a powder of the solid electrolyte or the like. Recently, however, regarding sulfide solid electrolytes, a solid electrolyte powder or a mixed powder of an electrode active material (positive electrode active material, negative electrode active material) and a solid electrolyte is slurried to obtain a solid electrolyte layer or an electrode active material layer ( A technique for forming an electrode mixture layer) has been developed. Various solvents (dispersion media) are known for use in forming the slurry (see, for example, Patent Documents 1 to 7).

In Patent Document 1, "the weight ratio of the active material (...) and the sulfide solid electrolyte (LiI-Li ₂ O-Li ₂ SP ₂ S ₅ ...) is active material: sulfide solid electrolyte = Weighed so as to be 75: 25. Further, the weight ratio of the main solvent (heptane ...) and the sub-solvent (n-butyl n-butyrate ...) was main solvent: sub-solvent = These were mixed so that the ratio was 80:20.Then, these were mixed so that the solid content rate was 63 wt%...a slurry positive electrode composition was produced.After that,...aluminum foil (... ) on the surface of ... a slurry-like positive electrode composition ... to prepare a positive electrode structure having a positive electrode current collector and a positive electrode.”, “The sulfide solid electrolyte is the positive electrode of the positive electrode structure A solid battery according to Example 1 was produced through the process of laminating the positive electrode structure, the sulfide solid electrolyte, and the negative electrode structure so that they are arranged between the and the negative electrode of the negative electrode structure.” ( See paragraphs [0037] and [0039]), and "In forming the positive electrode, the same procedure as in Example 1 above was performed except that ... anisole (...) was used as a co-solvent. Under these conditions, a solid battery according to Example 2 was produced." (see paragraph [0040]).

In Patent Document 2, ``a positive electrode active material (...) and a sulfide solid electrolyte (LiI-- _Li.sub.2O -- _{Li.sub.2SP.sub.2S.sub.5} ) have a weight _ratio of positive electrode active _material : sulfide solid electrolyte=. It was weighed and mixed so that the ratio was 75:25. ... n-decane (...) was prepared as a solvent, and the first solvent and the second solvent were weighed and mixed so that the volume ratio was the first solvent: second solvent = 90: 10. Thus, a mixed solvent was obtained.", "The mixed solvent was added to the positive electrode mixture to adjust the solid content concentration to 63% by weight.... By kneading, a positive electrode slurry was obtained. [ 0091] to [0093]), and "the first solvent used in the positive electrode slurry, the negative electrode slurry and the solid electrolyte slurry was changed to diisobutyl ketone (DIBK)", "the positive electrode slurry, the negative electrode slurry and changing the first solvent used for the solid electrolyte slurry to acetophenone” (see paragraphs [0103] and [0104]).

In Patent Document 3, "Li ₂ S..., P ₂ S ₅ ..., LiI... and LiBr... were weighed... to obtain a sulfide solid electrolyte." , "Silicon-based active material ... and the above-mentioned sulfide solid electrolyte ... were weighed and put into a dispersion solvent in which mesitylene and butyl butyrate were mixed in the ratio shown in Table 1 below, and then ... A negative electrode slurry for evaluation was obtained by mixing.” (paragraphs [0023] and [0024]). It is shown that the dispersion solvents of Examples 1 to 14 "could enhance the dispersibility of the solid content and the stability of the slurry" (paragraphs [0027] and [0028]).

In Patent Document 4, "[Example 1-1]", "(Synthesis of sulfide solid electrolyte material) ... sulfide solid electrolyte material (sulfide glass, Li ₂ S—Li ₂ OP ₂ S ₅ ) was obtained.”, “The sulfide solid electrolyte material and triethylamine were weighed so that the weight ratio of the sulfide solid electrolyte material: triethylamine was 40:60, and kneaded to obtain a slurry. ", "[Example 1-5] A slurry was obtained in the same manner as in Example 1-1, except that the sulfide solid electrolyte material was synthesized as follows.", "(Sulfide solid electrolyte Synthesis of material)... A sulfide solid electrolyte material (sulfide glass, LiI-Li ₂ SP ₂ S ₅ ) was obtained.” (from paragraph [0098] to [0100], [0107], [0108] ) and "[Examples 1-6 to 1-11] Instead of triethylamine, tributylamine, cyclopentyl methyl ether, dibutyl ether, anisole, n-butyl butyrate and ethyl benzoate were used. , a slurry was obtained in the same manner as in Examples 1-5.” (paragraph [0109]).

In Patent Document 5, "In the present invention, as the solid electrolyte to be contained in the solid electrolyte layer, a known solid electrolyte that can be used in a solid battery can be appropriately used. As such a solid electrolyte, Li ₃ PS ₄ , sulfide solid electrolytes such as Li ₂ SP 2 S ₅ prepared by mixing Li ₂ S and P ₂ S ₅ , _oxide solid electrolytes such as Li ₃ PO ₄ , and nitride solid electrolytes , and halide solid electrolytes, etc.... In addition, as the liquid used in producing the solid electrolyte layer, a slurry composition used in producing the solid electrolyte layer of the lithium ion secondary battery A known liquid that can be used when adjusting can be used as appropriate.As such a liquid, heptane can be exemplified, and a non-polar solvent can be preferably used."(Paragraph [0024] ). Further, "Heptane was added to the solid electrolyte (Li ₂ SP ₂ S ₅ ) prepared in the above steps to prepare a slurry-like solid electrolyte composition.", "Thickness: 15 μm A solid electrolyte layer having a thickness of 80 μm was formed by coating the prepared slurry-like solid electrolyte composition on the Al foil of … to prepare a foil-electrolyte laminate.” (Paragraph [0037 ], [0038]).

In Patent Document 6, "The solid electrolyte material in the present invention is not particularly limited as long as it is a material having Li ion conductivity, but for example, a sulfide solid electrolyte material, an oxide solid electrolyte material, a nitride solid electrolyte material, and inorganic solid electrolyte materials such as halide solid electrolyte materials.", "Sulfide solid electrolyte materials include, for example, Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S ₅ -LiI, Li ₂ SP ₂ S ₅ —LiCl, Li ₂ SP ₂ S ₅ —LiBr, etc.”, “… Examples of halide solid electrolyte materials include LiI, etc. can be done” (paragraphs [0031], [0032], [0035]). In addition, "20.5 parts by weight of the obtained sulfide solid electrolyte material (D ₅₀ = 0.8 µm) and 100 parts by weight of the positive electrode active material ... were weighed and dispersed in butyl butyrate as a dispersion medium. . 67.3 parts by weight of LiI--LiBr--Li ₂ SP ₂ S ₅ (D ₅₀ =1.5 μm) and 100 parts by weight of negative electrode active material were weighed and dispersed in butyl butyrate as a dispersion medium. . 100 parts by weight of LiI--LiBr--Li ₂ SP ₂ S ₅ (D ₅₀ =2.5 μm) was weighed and dispersed in heptane as a dispersion medium... Slurry for forming a solid electrolyte layer was prepared. obtained.", and "The obtained slurry was applied to a substrate ... to obtain a solid electrolyte layer" (paragraphs [0075] to [0080]).

In Patent Document 7, "The solid electrolyte in the present disclosure has ion conductivity. Examples of solid electrolytes include inorganic solid electrolytes such as sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, and halide solid electrolytes. electrolytes.", "Sulfide solid electrolytes include, for example, Li element, X element (X is at least one of P, Si, Ge, Sn, B, Al, Ga, In), and Examples include solid electrolytes containing element S. In addition, the sulfide solid electrolyte may further contain at least one of element O and halogen. include, for example, LiCl, LiI, and LiBr.", "The dispersion medium in the present disclosure imparts fluidity to the slurry. The dispersion medium may also dissolve some of the components of the slurry. Examples of the dispersion medium include esters such as butyl butyrate, dibutyl ether and ethyl acetate; ketones such as diisobutyl ketone (DIBK), methyl ketone and methyl propyl ketone; aromatic hydrocarbons such as xylene, benzene and toluene; heptane and dimethylbutane; , alkanes such as methylhexane, and amines such as tributylamine and allylamine” (paragraphs [0038] to [0040] and [0043]). In addition, "[Example 1] Lithium titanate (LTO) as an oxide active material, and a sulfide solid electrolyte (Li ₂ SP ₂ S ₅ system, average particle size 0.000) as a solid electrolyte. 5 μm, primary particles)... On the other hand, 90 parts by weight of butyl butyrate was prepared as a dispersion medium.", "As shown in Fig. 1, LTO was added to butyl butyrate. ... A precursor dispersion was obtained. A sulfide solid electrolyte was added to the obtained precursor dispersion ... to produce a slurry." (paragraphs [0062] and [0063]), Example 4] A slurry was produced in the same manner as in Example 1, except that the dispersion medium, active material, solid electrolyte, conductive material and binder as shown in Table 1 were used. Table 1 shows that Example 2 used dispersion medium: DIBK (diisobutyl ketone), active material: LTO, solid electrolyte: Li ₂ SP ₂ S ₅ , and Example 3 used dispersion medium: xylene, It shows that the active material: LTO and the solid electrolyte: Li ₂ SP ₂ S ₅ were used.

JP 2013-118143 A JP 2019-91632 A JP 2019-125468 A JP 2012-212652 A WO2013/014759 JP 2017-16793 A JP 2020-177755 A

As for the sulfide solid electrolyte, an invention is known in which a solvent (dispersion medium) such as butyl butyrate and diisobutyl ketone is used to form a slurry (see, for example, Patent Documents 1 to 4, 6, and 7).
However, as in the comparative examples described later, the inventors of the present invention prepared a halide solid electrolyte containing a lithium element and a metal element or metalloid element other than the lithium element as constituent elements using a solvent (dispersion medium) as described above. It has been found that when the solid electrolyte is made into a slurry (paste), the halide solid electrolyte is decomposed to form lithium halide, and the desired characteristics cannot be obtained.

In addition, inventions in which a sulfide solid electrolyte is made into a slurry using a solvent (dispersion medium) such as heptane, anisole, decane, mesitylene, dibutyl ether, and xylene are known (see, for example, Patent Documents 1 to 7). Furthermore, in Patent Documents 5 to 7, halide solid electrolytes such as LiCl, LiI, and LiBr are used as esters such as butyl butyrate, dibutyl ether, and ethyl acetate, ketones such as diisobutyl ketone (DIBK), methyl ketone, and methyl propyl ketone, and xylene. , benzene, toluene and other aromatic hydrocarbons, heptane, dimethylbutane, methylhexane and other alkanes. There is no disclosure of an invention in which the constituent halide solid electrolyte is made into a slurry (paste) using an organic solvent as described above.

An object of the present invention is to provide a highly stable paste containing an organic solvent that can suppress the formation of lithium halide due to decomposition of a halide solid electrolyte in the paste, and a solid electrolyte layer or electrode mixture layer that is a coating layer of the paste. and to provide a solid battery having the solid electrolyte layer or the electrode mixture layer.

A paste according to one aspect of the present invention contains a halide solid electrolyte and an organic solvent, and the halide solid electrolyte is Li, M and X (where M is a group consisting of metal elements other than Li and metalloid elements X is at least one selected from the group consisting of F, Cl, Br, and I), and the organic solvent comprises an aliphatic hydrocarbon, a ring At least one selected from a formula organic compound, a chain ether having two long-chain hydrocarbon groups with 4 or more carbon atoms, and a cyclic ether.
A solid electrolyte layer or an electrode mixture layer according to another aspect of the present invention is a coating layer of the paste.
A solid electrolyte layer or an electrode mixture layer according to still another aspect of the present invention comprises Li, M and X (wherein M is at least one selected from the group consisting of metal elements other than Li and metalloid elements, X is at least one selected from the group consisting of F, Cl, Br, and I) containing a halide solid electrolyte containing a halide composed of and the halogen in a powder X-ray diffraction diagram using CuKα The intensity ratio of the strongest diffraction peak of LiX to the strongest diffraction peak derived from the crystal structure of the compound solid electrolyte is 0.3 or less.
A solid battery according to still another aspect of the present invention has the solid electrolyte layer or the electrode mixture layer.

According to the paste according to one aspect of the present invention, a highly stable paste containing an organic solvent in which formation of lithium halide due to decomposition of a halide solid electrolyte in the paste is suppressed, and a solid that is a coating layer of the paste An electrolyte layer, an electrode mixture layer, and a solid battery having the solid electrolyte layer or electrode mixture layer can be provided.

FIG. 1 is a flowchart showing a procedure for obtaining a sample powder for evaluating the stability of a halide solid electrolyte in an organic solvent. FIG. 2 is a powder X-ray diffraction pattern of sample powder obtained by drying a paste obtained by kneading a halide solid electrolyte Li ₃ YCl ₆ with various organic solvents. FIG. 3 is a powder X-ray diffraction pattern of a sample powder obtained by drying a paste obtained by kneading a halide solid electrolyte Li ₃ InCl ₆ with organic solvents decane, tetralin, dibutyl ether, and butyl butyrate. FIG. 4 is a powder X-ray diffractogram of a sample powder obtained by drying a paste obtained by kneading a halide solid electrolyte Li ₂ ZrCl ₆ with organic solvents decane, tetralin, and butyl butyrate. FIG. 5 shows powder X-ray diffraction of a sample powder obtained by drying a paste obtained by kneading a halide solid electrolyte Li _3.2 Y _0.8 Mg _0.2 Cl ₆ with organic solvents decane, tetralin, and dibutyl ether. It is a diagram. FIG. 6 shows powder X-ray diffraction of a sample powder obtained by drying a paste obtained by kneading a halide solid electrolyte Li _3.2 Y _0.8 Ca _0.2 Cl ₆ with organic solvents decane, tetralin, and dibutyl ether. It is a diagram. FIG. 7 is a powder X-ray diffractogram of a sample powder obtained by drying a paste obtained by kneading a halide solid electrolyte Li ₃ Y _0.8 Fe _0.2 Cl ₆ with organic solvents decane, tetralin, and dibutyl ether. be. FIG. 8 shows a solid battery having a positive electrode mixture layer which is a paste coating layer containing Li ₃ YCl ₆ as a halide solid electrolyte and decane as an organic solvent, and Li ₃ YCl ₆ as a halide solid electrolyte. 3 shows charge-discharge curves of a solid battery having a positive electrode mixture layer, which is a paste layer containing butyl butyrate as an organic solvent. FIG. FIG. 9 is a see-through perspective view showing one embodiment of a solid-state battery. FIG. 10 is a schematic diagram showing an embodiment of a power storage device configured by assembling a plurality of solid-state batteries.

First, an outline of the paste, the solid electrolyte layer or the electrode mixture layer, and the solid battery having the solid electrolyte layer or the electrode mixture layer disclosed by the present specification will be described.

A paste according to one aspect of the present invention contains a halide solid electrolyte and an organic solvent, and the halide solid electrolyte is Li, M and X (where M is a group consisting of metal elements other than Li and metalloid elements X is at least one selected from the group consisting of F, Cl, Br, and I), and the organic solvent comprises an aliphatic hydrocarbon, a ring At least one selected from a formula organic compound, a chain ether having two long-chain hydrocarbon groups with 4 or more carbon atoms, and a cyclic ether. All of the organic solvents are liquid at room temperature and are dispersion media for dispersing the halide solid electrolyte in the paste.

According to this paste, as an organic solvent, at least one selected from aliphatic hydrocarbons, cyclic organic compounds, chain ethers having two long-chain hydrocarbon groups with 4 or more carbon atoms, and cyclic ethers. By containing Li, M and X (where M is at least one selected from the group consisting of metal elements and metalloid elements other than Li, X is selected from the group consisting of F, Cl, Br, and I The halide solid electrolyte containing a halide composed of (at least one of the above) is inhibited from decomposing to form LiX, and can be made highly stable.

M (metallic element and metalloid element other than Li) of the halide may be an element of Groups 2 to 15 of the periodic table. Elements of groups 2 to 13 are preferred, and elements of groups 2 and/or 3 are more preferred. These elements include Y, In, Zr, Zr, Mg, Ca, Fe, Er, Dy, Gd, Ho, La, Nd, Sc, Sm, Tb, Tm, Al, Ti, Ga, and Ge. be done. As the halide, compounds represented by the general formula _LixMyX6 (x and y are _each a real number _of 1 or more) are preferable, _{such as Li3YCl6} , _Li3YBr6 , _{Li3YI6 ,} and _{Li3. InCl6 , Li3InBr6 , Li3InF6} , _Li2ZrCl6 , _LixYyMgzCl6 ( _x + _{3y +} 2z ₌ 6 ₎ , _{LixYyCazCl6 (} x+3y ₊ 2z= ₆ ), _{Li3Yy FezCl6 (} y ₊ z=1 ₎ , _{Li3ErCl6 , Li3ErBr6} , _{Li3DyCl6 , Li3DyBr6 ,} Li3GdCl6 _{, Li3GdBr6 , Li3HoCl6 , Li3HoBr6 , Li3LaCl6 , Li3LaBr6 , Li3NdCl6 , Li3NdBr6 , Li3ScCl6 , Li3ScBr6 , Li3ScF6 , Li3SmCl6 , Li3SmBr6 , Li3TbCl6 ,} Li ₃ TbBr ₆ , Li ₃ TmCl ₆ , Li ₃ TmBr ₆ , Li ₃ AlF ₆ , Li ₃ TiF ₆ , Li ₃ GaF ₆ , Li ₃ GeF ₆ and the like.

M of the halide is more preferably one or more selected from the group consisting of Y, In, Zr, Mg, Ca and Fe.
The halides include Li ₃ YCl ₆ , Li ₃ InCl ₆ , Li ₂ ZrCl ₆ , Li _3.2 Y _0.8 Mg _0.2 Cl ₆ , Li _3.2 Y _0.8 Ca _0.2 Cl ₆ , Li ₃ Y _0.8 Fe _0.2 Cl ₆ are particularly preferred.

If one or more selected from the group consisting of Y, In, Zr, Mg, Ca, and Fe is employed as M, the decomposition of the halide solid electrolyte to generate LiX is further suppressed, and It can be made into a highly stable paste.

When the organic solvent contains an aliphatic hydrocarbon, the aliphatic hydrocarbon is preferably an alkane, more preferably an aliphatic hydrocarbon having a long-chain hydrocarbon group of 7 or more carbon atoms, heptane, and decane It may be one or more selected from.

If an aliphatic hydrocarbon having a long-chain hydrocarbon group with 7 or more carbon atoms is employed, steric hindrance occurs due to the presence of the long-chain hydrocarbon group, and the halide interacts with the metal or metalloid (M) ion. Therefore, the decomposition of the halide solid electrolyte to generate LiX is further suppressed, and a more stable paste can be obtained.

When the organic solvent contains a cyclic organic compound, the cyclic organic compound may be an aromatic compound or an alicyclic compound. When the cyclic organic compound is an aromatic compound, it may be an aromatic hydrocarbon or an aromatic compound having an ether bond, and may be selected from the group consisting of tetralin, cumene, mesitylene, and anisole. 1 or more are preferable. When the cyclic organic compound is an alicyclic compound, it may be an alicyclic hydrocarbon or an alicyclic compound having an ether bond.

If a cyclic organic compound is employed, steric hindrance occurs due to the presence of a ring structure such as an aromatic ring, which is thought to suppress the interaction of the halide with metal or metalloid (M) ions. The decomposition of the solid electrolyte to generate LiX is further suppressed, and a more stable paste can be obtained.

Preferably, the organic solvent does not contain a hetero element. Since the metal or metalloid (M) ion of the halide has a high charge density, if there is a heteroatom in which electrons are localized such as an oxygen atom or a nitrogen atom in the organic solvent, the electrostatic interaction with the oxygen atom etc. Easy to coordinate. When the metal or metalloid (M) ion of the halide is coordinated to the heteroatom to form a complex soluble in the organic solvent, the halide solid electrolyte is decomposed. For example, among metal or metalloid (M) ions, Zr ⁴⁺ , In ³⁺ , Fe ³⁺ and the like have higher charge densities than Y ³⁺ , and thus have a large electrostatic interaction.

When the organic solvent contains an ether compound, the ether compound may be a chain ether having two long-chain hydrocarbon groups having 4 or more carbon atoms, such as dibutyl ether or dipentyl ether, or a cyclic ether such as tetrahydrofuran. Preferably, the chain ether having two long-chain hydrocarbon groups having 4 or more carbon atoms is one or more selected from the group consisting of dibutyl ether, dipentyl ether, and tetrahydrofuran as the cyclic ether. Ether compounds have an oxygen element, which is a hetero element, and are considered to be effective when steric hindrance occurs due to the presence of long-chain hydrocarbon groups or ring structures. A cyclic ether is an ether compound having an oxygen element in the ring structure. The anisole is an ether compound different from a chain ether having two long-chain hydrocarbon groups having 4 or more carbon atoms and a cyclic ether, but since it is an aromatic compound, it is effective for the same reason as above. is considered to play

By employing these ether compounds, the decomposition of the halide solid electrolyte to generate LiX is further suppressed, and a more stable paste can be obtained.

A solid electrolyte layer or an electrode mixture layer according to another aspect of the present invention is a coating layer of the paste. Here, the solid electrolyte layer includes the halide solid electrolyte, and the electrode mixture layer includes the electrode active material and the halide solid electrolyte.
Moreover, the electrode mixture layer is a positive electrode mixture layer or a negative electrode mixture layer, which will be described later. The positive electrode mixture layer preferably contains the positive electrode active material and the halide solid electrolyte, and the negative electrode mixture layer preferably contains the negative electrode active material and the halide solid electrolyte.

According to this solid electrolyte layer or electrode mixture layer, the decomposition of the halide solid electrolyte to produce lithium halide is suppressed, so that the ionic conductivity of the solid electrolyte layer or electrode mixture layer does not decrease. can be suppressed.

A solid electrolyte layer or an electrode mixture layer according to still another aspect of the present invention comprises Li, M and X (wherein M is at least one selected from the group consisting of metal elements other than Li and metalloid elements, X is at least one selected from the group consisting of F, Cl, Br, and I) containing a halide solid electrolyte containing a halide composed of and the halogen in a powder X-ray diffraction diagram using CuKα The intensity ratio of the strongest diffraction peak of LiX to the strongest diffraction peak derived from the crystal structure of the compound solid electrolyte is 0.3 or less. Here, the solid electrolyte layer or the electrode mixture layer is preferably a coating layer.
M of the halide is preferably one or more selected from the group consisting of Y, In, Zr, Mg, Ca and Fe.
The halides include Li ₃ YCl ₆ , Li ₃ InCl ₆ , Li ₂ ZrCl ₆ , Li _3.2 Y _0.8 Mg _0.2 Cl ₆ , Li _3.2 Y _0.8 Ca _0.2 Cl ₆ , Li ₃ Y _0.8 Fe _0.2 Cl ₆ are more preferred.
The details of the electrode mixture layers (positive electrode mixture layer, negative electrode mixture layer) are as described above.

According to this solid electrolyte layer or electrode mixture layer, since the LiX content ratio with respect to the halide solid electrolyte is small, it is possible to suppress the decrease in the ionic conductivity of the solid electrolyte layer or electrode mixture layer.

<X-ray diffraction measurement>
The X-ray diffraction measurement of the solid electrolyte layer or electrode mixture layer (positive electrode mixture layer, negative electrode mixture layer) is performed as follows.
When the solid electrolyte layer, the positive electrode mixture layer, and the negative electrode mixture layer are available before manufacturing the solid battery, a sample is taken from the solid electrolyte layer or the electrode mixture layer. When collecting samples from the positive electrode, negative electrode, and solid electrolyte taken out after dismantling the solid battery, before dismantling the solid battery, discharge the nominal capacity (Ah) of the solid battery for 10 minutes at a current that can be discharged in 1 hour. At a current (A) that is 1, constant current discharge is performed until the battery voltage reaches the lower limit of the voltage specified during normal use, and the battery is in a completely discharged state. After adjusting to a fully discharged state, the solid battery is disassembled, and the positive electrode mixture layer, the negative electrode mixture layer, and the solid electrolyte layer are taken out.
The positive electrode mixture layer, negative electrode mixture layer, and solid electrolyte layer collected from the removed positive electrode mixture layer, negative electrode mixture layer, and solid electrolyte layer were lightly pulverized in an agate mortar and placed in a sample holder for X-ray diffraction measurement for measurement. provide. The positive electrode mixture and the negative electrode mixture preferably include a step of separating the active material, binder, etc. in the mixture to extract the solid electrolyte.
In this specification, the X-ray diffraction measurement is performed under the following conditions. A Rigaku X-ray diffractometer "MiniFlex II" is used, the radiation source is CuKα rays, the tube voltage is 30 kV, and the tube current is 15 mA. The sampling width is 0.01 deg, the scanning speed is 1.0 deg/min, the divergence slit width is 0.625 deg, the light receiving slit is open, and the scattering slit width is 8.0 mm.

<Method for calculating intensity ratio of diffraction peaks>
A method for calculating the intensity ratio of the strongest diffraction peak of LiX to the strongest diffraction peak derived from the crystal structure of the halide solid electrolyte from the powder X-ray diffraction pattern is as follows.
Rigaku software PDXL is used to obtain calculated data from X-ray diffraction measurement data by automatic reading, and the intensity of the diffraction peak is read. The autoreading process includes smoothing, background processing, background refinement, Kα2 removal, and autofitting to obtain calculated data. Since the background changes depending on the measurement conditions, it is preferable to adjust the background processing conditions for each X-ray diffraction measurement data.
The position of the strongest diffraction peak derived from the crystal structure of the halide solid electrolyte is the most intense among the diffraction peaks obtained by X-ray diffraction measurement of the as-synthesized halide solid electrolyte or a commercially available halide solid electrolyte. is identified by selecting diffraction peaks with high .
The position of the strongest diffraction peak of LiX is based on the sample in which the diffraction peak of LiX generated by decomposition of the halide solid electrolyte with an organic solvent is observed, and the diffraction peak with the highest intensity among the diffraction peaks of LiX Identify by selecting a peak. For example, for LiCl, diffraction peaks are observed at 2θ of 30°, 35°, 50°, and 59° in a powder X-ray diffraction pattern using CuKα rays. ±0.6°) is the strongest diffraction peak, so the position of the strongest diffraction peak is set at around 30°.
Calculate the ratio of the intensity of the diffraction peak at the position of the strongest diffraction peak of LiX to the intensity of the diffraction peak at the position of the strongest diffraction peak derived from the crystal structure of the halide solid electrolyte read by the above method, The intensity ratio of the strongest diffraction peak of LiX to the strongest diffraction peak derived from the crystal structure of the compound solid electrolyte.

In the solid electrolyte layer or electrode mixture layer, M in the halide solid electrolyte may be one or more selected from the group consisting of Y, In, Zr, Mg, Ca, and Fe.

If one or more selected from the group consisting of Y, In, Zr, Mg, Ca, and Fe is employed as M, the decomposition of the halide solid electrolyte to generate LiX is further suppressed. , the decrease in the ionic conductivity of the solid electrolyte layer or the electrode mixture layer can be further suppressed.

A solid battery according to still another aspect of the present invention has the solid electrolyte layer or the electrode mixture layer.

According to this solid battery, it is possible to obtain a solid electrolyte layer or an electrode mixture layer in which the halide solid electrolyte is inhibited from decomposing to form LiX, and a decrease in ionic conductivity is inhibited.

A configuration of a solid-state battery, a configuration of a power storage device, a method for manufacturing a solid-state battery, and other embodiments according to one embodiment of the present invention (hereinafter referred to as "this embodiment") will be described in detail. Note that the name of each component (each component) used in each embodiment may be different from the name of each component (each component) used in the background art.

<Structure of Solid Battery>
A solid battery according to the present embodiment includes an electrode body having a positive electrode, a negative electrode, and a solid electrolyte layer, and a container that accommodates the electrode body. A non-aqueous electrolyte may be interposed between at least one of the solid electrolyte layer and the negative electrode and between the solid electrolyte layer and the positive electrode. The electrode body is usually a laminated type in which a plurality of positive electrodes and a plurality of negative electrodes are laminated with a solid electrolyte layer interposed therebetween, or a wound type in which a positive electrode and a negative electrode are laminated with a solid electrolyte layer interposed therebetween and wound. is. When the non-aqueous electrolyte is interposed, the non-aqueous electrolyte may exist in a state of being contained in any one of the positive electrode, the negative electrode, and the solid electrolyte layer. Also, the electrode body may be of a so-called “bipolar type” in which a positive electrode mixture layer is formed on one surface of a base material and a negative electrode mixture layer is formed on the other surface thereof.

(positive electrode)
The positive electrode has a positive electrode base material and a positive electrode material mixture layer arranged directly on the positive electrode base material or via an intermediate layer.

A positive electrode base material has electroconductivity. Whether or not a material has "conductivity" is determined using a volume resistivity of 10 ⁷ Ω·cm as a threshold measured according to JIS-H-0505 (1975). As the material for the positive electrode substrate, metals such as aluminum, titanium, tantalum and stainless steel, or alloys thereof are used. Among these, aluminum or an aluminum alloy is preferable from the viewpoint of potential resistance, high conductivity, and cost. Examples of the positive electrode substrate include foil, deposited film, mesh, porous material, and the like, and foil is preferable from the viewpoint of cost. Therefore, aluminum foil or aluminum alloy foil is preferable as the positive electrode substrate. Examples of aluminum or aluminum alloy include A1085, A3003, A1N30, etc. defined in JIS-H-4000 (2014) or JIS-H-4160 (2006).

The average thickness of the positive electrode substrate is preferably 3 μm or more and 50 μm or less, more preferably 5 μm or more and 40 μm or less, even more preferably 8 μm or more and 30 μm or less, and particularly preferably 10 μm or more and 25 μm or less. By setting the average thickness of the positive electrode substrate within the above range, it is possible to increase the strength of the positive electrode substrate and increase the energy density per volume of the solid battery.

The intermediate layer is a layer arranged between the positive electrode substrate and the positive electrode material mixture layer. The intermediate layer contains a conductive agent such as carbon particles to reduce the contact resistance between the positive electrode substrate and the positive electrode mixture layer. The composition of the intermediate layer is not particularly limited, and includes, for example, a binder and a conductive agent.

The positive electrode mixture layer contains a positive electrode active material. In this embodiment, the positive electrode mixture layer preferably contains a halide solid electrolyte. The positive electrode material mixture layer contains arbitrary components such as a conductive agent, a binder (binder), a thickener, a filler, etc., as required.

The positive electrode active material can be appropriately selected from known positive electrode active materials. As a positive electrode active material for lithium ion secondary batteries, a material capable of intercalating and deintercalating lithium ions is usually used. Examples of positive electrode active materials include lithium-transition metal composite oxides having an α-NaFeO ₂ type crystal structure, lithium-transition metal composite oxides having a spinel-type crystal structure, polyanion compounds, chalcogen compounds, and sulfur. Examples of lithium transition metal composite oxides having an α-NaFeO ₂ type crystal structure include Li[Li _x Ni _(1-x) ]O ₂ (0≦x<0.5), Li[Li _x Ni _γ Co _{( 1-x-γ)} ]O ₂ (0≦x<0.5, 0<γ<1), Li[Li _x Co _(1-x) ]O ₂ (0≦x<0.5), Li[ Li _x Ni _γ Mn _(1-x-γ) ]O ₂ (0≦x<0.5, 0<γ<1), Li[Li _x Ni _γ Mn _β Co _(1-x-γ-β) ] O ₂ (0≦x<0.5, 0<γ, 0<β, 0.5<γ+β<1), Li[Li _x Ni _γ Co _β Al _(1-x-γ-β) ]O ₂ ( 0≦x<0.5, 0<γ, 0<β, 0.5<γ+β<1) and the like. Examples of lithium transition metal composite oxides having a spinel crystal structure include Li _x Mn ₂ O ₄ and Li _x Ni _γ Mn _(2-γ) O ₄ . Examples of polyanion compounds include _{LiFePO4 , LiMnPO4} , LiNiPO4 _{, LiCoPO4 , Li3V2} ( _PO4 ) ₃ , _{Li2MnSiO4 , Li2CoPO4F} and the like. Examples of chalcogen compounds include titanium disulfide, molybdenum disulfide, and molybdenum dioxide. The atoms or polyanions in these materials may be partially substituted with atoms or anionic species of other elements. These materials may be coated with other materials on their surfaces. As the positive electrode active material, one of these materials may be used alone, or two or more thereof may be mixed and used.

The positive electrode active material is usually particles (powder). The average particle size of the positive electrode active material is preferably, for example, 0.1 μm or more and 20 μm or less. By making the average particle size of the positive electrode active material equal to or more than the lower limit, the production or handling of the positive electrode active material becomes easy. By making the average particle size of the positive electrode active material equal to or less than the upper limit, the capacity during high-rate discharge can be increased. Note that when a composite of a positive electrode active material and another material is used, the average particle size of the composite is taken as the average particle size of the positive electrode active material. "Average particle size" is based on JIS-Z-8825 (2013), based on the particle size distribution measured by a laser diffraction / scattering method for a diluted solution in which particles are diluted with a solvent, JIS-Z-8819 -2 (2001) means a value at which the volume-based integrated distribution calculated according to 50%.

A pulverizer, a classifier, or the like is used to obtain the positive electrode active material with a predetermined particle size. Pulverization methods include, for example, methods using a mortar, ball mill, sand mill, vibrating ball mill, planetary ball mill, jet mill, counter jet mill, whirling jet mill, or sieve. At the time of pulverization, wet pulverization in which water or an organic solvent such as hexane is allowed to coexist can also be used. As a classification method, a sieve, an air classifier, or the like is used as necessary, both dry and wet.

The content of the positive electrode active material in the positive electrode mixture layer is preferably 33% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and even more preferably 60% by mass or more and 80% by mass or less. By setting the content of the positive electrode active material within the above range, it is possible to achieve both high energy density of the positive electrode mixture layer and manufacturability.

The halide solid electrolyte contained in the positive electrode mixture layer contains Li, M and X (where M is at least one selected from the group consisting of metal elements and metalloid elements other than Li, X is F, Cl, Br , and at least one selected from the group consisting of I). As for M, it is preferable to use at least one selected from the group consisting of the aforementioned metal elements and metalloid elements. As the solid electrolyte, a sulfide solid electrolyte or the like, which will be described later, other than the halide solid electrolyte may be used in combination.
The content of the solid electrolyte in the positive electrode mixture layer is preferably 5% by mass or more and 67% by mass or less, more preferably 10% by mass or more and 50% by mass or less, and even more preferably 20% by mass or more and 40% by mass or less.

The conductive agent is not particularly limited as long as it is a conductive material. Examples of such conductive agents include carbonaceous materials, metals, and conductive ceramics. Carbonaceous materials include graphite, non-graphitic carbon, graphene-based carbon, and the like. Examples of non-graphitic carbon include carbon nanofiber, pitch-based carbon fiber, and carbon black. Examples of carbon black include furnace black, acetylene black, and ketjen black. Graphene-based carbon includes graphene, carbon nanotube (CNT), fullerene, and the like. The shape of the conductive agent may be powdery, fibrous, or the like. As the conductive agent, one type of these materials may be used alone, or two or more types may be mixed and used. Also, these materials may be combined for use. For example, a composite material of carbon black and CNT may be used. Among these, carbon black is preferable from the viewpoint of electron conductivity and coatability, and acetylene black is particularly preferable.

The content of the conductive agent in the positive electrode mixture layer is preferably 1% by mass or more and 10% by mass or less, more preferably 3% by mass or more and 9% by mass or less. By setting the content of the conductive agent within the above range, the energy density of the solid-state battery can be increased.

Binders include, for example, fluorine resins (polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.), thermoplastic resins such as polyethylene, polypropylene, polyacryl, and polyimide; ethylene-propylene-diene rubber (EPDM), sulfone Elastomers such as modified EPDM, styrene-butadiene rubber (SBR) and fluororubber; polysaccharide polymers and the like.

The content of the binder in the positive electrode mixture layer is preferably 1% by mass or more and 10% by mass or less, more preferably 3% by mass or more and 9% by mass or less. By setting the content of the binder within the above range, the active material can be stably retained.

Examples of thickeners include polysaccharide polymers such as carboxymethylcellulose (CMC) and methylcellulose. When the thickener has a functional group that reacts with lithium or the like, the functional group may be previously deactivated by methylation or the like.

A filler is not specifically limited. Fillers include polyolefins such as polypropylene and polyethylene, inorganic oxides such as silicon dioxide, alumina, titanium dioxide, calcium oxide, strontium oxide, barium oxide, magnesium oxide and aluminosilicate, magnesium hydroxide, calcium hydroxide, hydroxide Hydroxides such as aluminum, carbonates such as calcium carbonate, sparingly soluble ionic crystals such as calcium fluoride, barium fluoride, and barium sulfate, nitrides such as aluminum nitride and silicon nitride, talc, montmorillonite, boehmite, zeolite, Mineral resource-derived substances such as apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, and mica, or artificial products thereof may be used.

The positive electrode mixture layer contains typical nonmetallic elements such as B, N, P, F, Cl, Br, and I, Li, Na, Mg, Al, K, Ca, Zn, Ga, Ge, Sn, Sr, Ba, and the like. and transition metal elements such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, Nb, and W are used as positive electrode active materials, solid electrolytes, conductive agents, binders, thickening It may be contained as a component other than agents and fillers.

(Manufacturing method of positive electrode)
In order to manufacture the positive electrode in this embodiment, the positive electrode active material, Li, M and X (where M is at least one selected from the group consisting of metal elements other than Li and metalloid elements, X is F, Cl , Br, and at least one selected from the group consisting of I). , and an organic solvent containing at least one selected from aliphatic hydrocarbons, cyclic organic compounds, chain ethers having two long-chain hydrocarbon groups with 4 or more carbon atoms, and cyclic ethers ( It is preferable that the positive electrode mixture layer is formed by kneading the dispersion medium) to prepare a paste for forming a positive electrode mixture layer, applying this paste to a positive electrode substrate or the like, and drying the paste.

The mass ratio of the positive electrode active material to the solid electrolyte contained in the positive electrode mixture layer-forming paste is preferably in the range of 0.5 to 20, and more preferably in the range of 1 to 10. .
The solid content in the positive electrode mixture layer-forming paste is preferably in the range of 40% by mass or more and 80% by mass or less, and more preferably in the range of 50% by mass or more and 70% by mass or less. Here, the solid content refers to the ratio of the mass excluding the mass of the organic solvent (dispersion medium) to the mass of the positive electrode mixture layer-forming paste.
A positive electrode active material, a solid electrolyte containing a halide solid electrolyte, and optionally optional components such as a conductive agent, a binder, a thickener, a filler, etc., in the above-mentioned mass proportions, aliphatic hydrocarbons, cyclic organic compounds , a chain ether having two long-chain hydrocarbon groups with 4 or more carbon atoms, and an organic solvent (dispersion medium) containing at least one selected from a cyclic ether to form a paste.
The paste for forming the positive electrode mixture layer may contain an aliphatic hydrocarbon, a cyclic organic compound, a chain ether having two long-chain hydrocarbon groups with 4 or more carbon atoms, and an organic solvent other than the cyclic ether. may be included as long as it does not impair the effect of
The kneading method is not particularly limited as long as a highly dispersible paste can be obtained. A general method using a homogenizer, a shaker or the like can be adopted.

The positive electrode mixture layer-forming paste can be applied to the positive electrode base material, but it can also be applied to the solid electrolyte layer.
The method of applying the paste for forming the positive electrode mixture layer is not particularly limited. method can be adopted.
The thickness of the coating layer of the positive electrode mixture layer-forming paste is appropriately selected according to the desired thickness of the electrode mixture layer.

The method for drying the coated layer of the paste for forming the positive electrode mixture layer is not particularly limited as long as it does not deteriorate the positive electrode mixture layer. Common methods such as dielectric heating drying can be employed. Examples of the drying atmosphere include inert gas atmosphere such as argon gas atmosphere and nitrogen gas atmosphere, air atmosphere, and vacuum.
As drying conditions, for example, it is preferable to dry at 80° C. to 150° C. for 10 minutes to 12 hours.
The manufacturing method of the positive electrode in this embodiment may have arbitrary steps in addition to the steps described above. Examples of such a process include a compression process. By including the compression step, a high-density positive electrode mixture layer can be obtained, and a high energy density can be achieved by thinning the positive electrode mixture layer.
By the above method, a positive electrode having a positive electrode mixture layer, which is a paste coating layer, can be manufactured.

(negative electrode)
The negative electrode has a negative electrode base material and a negative electrode mixture layer disposed on the negative electrode base material directly or via an intermediate layer. The structure of the intermediate layer is not particularly limited, and can be selected from, for example, the structures exemplified for the positive electrode.

A negative electrode base material has electroconductivity. As materials for the negative electrode substrate, metals such as copper, nickel, stainless steel, nickel-plated steel, aluminum, alloys thereof, carbonaceous materials, and the like are used. Among these, copper or a copper alloy is preferred. Examples of the negative electrode substrate include foil, deposited film, mesh, porous material, and the like, and foil is preferable from the viewpoint of cost. Therefore, copper foil or copper alloy foil is preferable as the negative electrode substrate. Examples of copper foil include rolled copper foil and electrolytic copper foil.

The average thickness of the negative electrode substrate is preferably 2 μm or more and 35 μm or less, more preferably 3 μm or more and 30 μm or less, even more preferably 4 μm or more and 25 μm or less, and particularly preferably 5 μm or more and 20 μm or less. By setting the average thickness of the negative electrode substrate within the above range, it is possible to increase the strength of the negative electrode substrate and increase the energy density per unit volume of the solid battery.

The negative electrode mixture layer contains a negative electrode active material. In the present embodiment, the negative electrode mixture layer preferably contains a halide solid electrolyte. The negative electrode mixture layer contains arbitrary components such as a conductive agent, a binder, a thickener, a filler, etc., if necessary. The solid electrolyte such as the halide solid electrolyte contained in the negative electrode mixture layer is the same as the solid electrolyte such as the halide solid electrolyte contained in the positive electrode mixture layer. Optional components such as a conductive agent, a binder, a thickener, and a filler can be selected from the materials exemplified for the positive electrode.

The negative electrode mixture layer contains typical nonmetallic elements such as B, N, P, F, Cl, Br, and I, Li, Na, Mg, Al, K, Ca, Zn, Ga, Ge, Sn, Sr, Ba, and the like. Typical metal elements, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, Ta, Hf, Nb, W and other transition metal elements are used as negative electrode active materials, solid electrolytes, conductive agents, You may contain as components other than a binder, a thickener, and a filler.

The negative electrode active material can be appropriately selected from known negative electrode active materials. Materials capable of intercalating and deintercalating lithium ions are usually used as negative electrode active materials for lithium ion secondary batteries. Examples of the negative electrode active material include metal Li; metals or metalloids such as Si and Sn; metal oxides and metalloid oxides such as Si oxide, Ti oxide and Sn oxide; Li ₄ Ti ₅ O ₁₂ ; Titanium-containing oxides such as LiTiO _{2 and} TiNb ₂ O ₇ ; polyphosphate compounds; silicon carbide; carbon materials such as graphite and non-graphitizable carbon (easily graphitizable carbon or non-graphitizable carbon) be done. Among these materials, graphite and non-graphitic carbon are preferred. In the negative electrode mixture layer, one type of these materials may be used alone, or two or more types may be mixed and used.

“Graphite” refers to a carbon material having an average lattice spacing (d ₀₀₂ ) of the (002) plane of 0.33 nm or more and less than 0.34 nm as determined by X-ray diffraction before charging/discharging or in a discharged state. Graphite includes natural graphite and artificial graphite. Artificial graphite is preferable from the viewpoint that a material with stable physical properties can be obtained.

“Non-graphitic carbon” refers to a carbon material having an average lattice spacing (d ₀₀₂ ) of the (002) plane of 0.34 nm or more and 0.42 nm or less as determined by X-ray diffraction before charging/discharging or in a discharged state. . Non-graphitizable carbon includes non-graphitizable carbon and graphitizable carbon. Examples of non-graphitic carbon include resin-derived materials, petroleum pitch or petroleum pitch-derived materials, petroleum coke or petroleum coke-derived materials, plant-derived materials, and alcohol-derived materials.

Here, the term “discharged state” means a state in which the carbon material, which is the negative electrode active material, is discharged such that lithium ions that can be intercalated and deintercalated are sufficiently released during charging and discharging. For example, in a half-cell using a negative electrode containing a carbon material as a negative electrode active material as a working electrode and metal Li as a counter electrode, the open circuit voltage is 0.7 V or higher.

The term “non-graphitizable carbon” refers to a carbon material having a d ₀₀₂ of 0.36 nm or more and 0.42 nm or less.

“Graphitizable carbon” refers to a carbon material having a d ₀₀₂ of 0.34 nm or more and less than 0.36 nm.

The negative electrode active material is usually particles (powder). The average particle size of the negative electrode active material can be, for example, 1 nm or more and 100 μm or less. When the negative electrode active material is a carbon material, a titanium-containing oxide or a polyphosphate compound, the average particle size may be 1 μm or more and 100 μm or less. When the negative electrode active material is Si, Sn, Si oxide, Sn oxide, or the like, the average particle size may be 1 nm or more and 1 μm or less. By making the average particle size of the negative electrode active material equal to or greater than the above lower limit, the production or handling of the negative electrode active material is facilitated. By setting the average particle size of the negative electrode active material to the above upper limit or less, the capacity during high-rate discharge can be increased. A pulverizer, a classifier, or the like is used to obtain the negative electrode active material with a predetermined particle size. The pulverization method and classification method can be selected from, for example, the methods exemplified for the positive electrode. When the negative electrode active material is metal such as metal Li, the negative electrode active material may be foil-shaped.

The content of the negative electrode active material in the negative electrode mixture layer is preferably 33% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and even more preferably 60% by mass or more and 80% by mass or less. By setting the content of the negative electrode active material within the above range, it is possible to achieve both high energy density of the negative electrode mixture layer and manufacturability.

(Manufacturing method of negative electrode)
In order to manufacture the negative electrode in the present embodiment, the negative electrode active material, Li, M and X (where M is at least one selected from the group consisting of metal elements and metalloid elements other than Li, X is F, Cl , Br, and at least one selected from the group consisting of I). , and an organic solvent containing at least one selected from aliphatic hydrocarbons, cyclic organic compounds, chain ethers having two long-chain hydrocarbon groups with 4 or more carbon atoms, and cyclic ethers ( dispersion medium) to prepare a paste for forming a negative electrode mixture layer, apply this paste to a negative electrode substrate or the like, and dry it to form a negative electrode mixture layer.
A negative electrode active material, a solid electrolyte containing a halide solid electrolyte, and optionally optional components such as a conductive agent, a binder, a thickener, a filler, etc., in the same mass ratio as in the case of forming the positive electrode mixture layer, and aliphatic Kneaded with an organic solvent (dispersion medium) containing at least one selected from hydrocarbons, cyclic organic compounds, chain ethers having two long-chain hydrocarbon groups with 4 or more carbon atoms, and cyclic ethers A negative electrode can be manufactured by preparing a paste for forming a negative electrode mixture layer and performing the same method as the above-described “method for manufacturing a positive electrode”.

(solid electrolyte)
In the present embodiment, the solid electrolyte contains a halide solid electrolyte, and the halide solid electrolyte is Li, M and X (wherein M is at least selected from the group consisting of metal elements other than Li and metalloid elements). and X is at least one selected from the group consisting of F, Cl, Br, and I). Here, "composed of Li, M and X" means that the halide is a compound composed of the elements Li, M and X, and the halide is composed of the halide solid electrolyte It does not exclude the inclusion of small amounts of other components other than the elements that M mentioned above includes the metal elements and metalloid elements described above, and is preferably one or more selected from the group consisting of Y, In, Zr, Mg, Ca, and Fe. As said X, Cl is preferable. As the halide, a _compound represented by the general formula _LixMyCl6 (x and y are _{each a} real number of 1 _or more) is preferable, such as _Li3YCl6 , _{Li3InCl6 , Li2ZrCl6} , _{Li3. 2Y0.8Mg0.2Cl6 , Li3.2Y0.8Ca0.2Cl6 , Li3Y0.8Fe0.2Cl6 and the like are particularly preferred .} A compound represented by the general formula Li _{x My} Cl ₄ (where x and y are each a real number of 1 or more) may also be used. Examples include Li ₂ MgCl ₄ and Li ₂ FeCl ₄ .
As the solid electrolyte, a sulfide solid electrolyte other than the halide solid electrolyte, an oxide solid electrolyte, or the like may be used in combination. Sulfide solid electrolytes include Li ₂ SP ₂ S ₅ , LiI- _{Li 2} SP 2 S ₅ , Li ₁₀ Ge-P ₂ S ₁₂ , Li ₂ SP ₂ S ₅ -LiCl, Li ₂ S _-P2S5 - _{LiBr , Li2SP2S5 - Li2O , Li2SP2S5 - Li2O} -LiI, _{Li2SP2S5 - Li3N} , _{Li 2S} —SiS ₂ , Li ₂ S—SiS ₂ —LiI, Li ₂ S—SiS ₂ —LiBr, Li ₂ S—SiS ₂ —LiCl, Li ₂ S—SiS ₂ —B ₂ S ₃ —LiI, Li ₂ S -SiS ₂ -P ₂ S ₅ -LiI, Li ₂ S-B ₂ S ₃ , Li ₂ SP ₂ S ₅ -Z _m S _2n (where m and n are positive numbers, Z is Ge, Zn , Ga.), Li ₂ S—GeS ₂ , Li ₂ S—SiS ₂ —Li ₃ PO ₄ , Li ₂ S—SiS ₂ —Li _x MO _y (where x and y are positive numbers , M is any one of P, Si, Ge, B, Al, Ga, and In.) and the like.
The content of the halide solid electrolyte is preferably 20% by mass or more and 100% by mass or less of the total solid electrolyte, and the other solid electrolyte such as a sulfide solid electrolyte is 0% by mass or more and 80% by mass of the total solid electrolyte. They can be used together in the following proportions.

(Method for producing solid electrolyte layer)
In order to produce a solid electrolyte layer in the present embodiment, Li, M and X (where M is at least one selected from the group consisting of metal elements and metalloid elements other than Li, X is F, Cl, Br , and at least one selected from the group consisting of I), and an aliphatic hydrocarbon, a cyclic organic compound, and a solid electrolyte having 4 or more carbon atoms. An organic solvent (dispersion medium) containing at least one selected from a chain ether having two long-chain hydrocarbon groups and a cyclic ether is kneaded to prepare a solid electrolyte layer forming paste, and this paste is is preferably applied to the substrate and dried to form the solid electrolyte layer.

The solid electrolyte layer-forming paste contains at least the halide solid electrolyte and the organic solvent, and if necessary, further contains other materials such as binders, thickeners, and fillers. good too. Among others, it is preferable to further contain a binder. The binder can be selected from the materials exemplified for the positive electrode. The solid electrolyte layer-forming slurry prepared in this step contains at least the sulfide solid electrolyte material and the dispersion medium, and if necessary, further contains other materials such as a nonpolar solvent and a binder. It's okay to be Among others, in this step, it is preferable to further add a binder to prepare the slurry for forming the solid electrolyte layer. The binder may be the same as described in "A. Slurry" above.

The content of the halide solid electrolyte in the solid electrolyte layer-forming paste is preferably in the range of 10% by mass or more and 90% by mass or less, and is in the range of 40% by mass or more and 70% by mass or less. is more preferred.

The solid electrolyte layer-forming paste can be applied to, for example, a metal foil, a fluororesin sheet, or other releasable material, an electrode mixture layer, or the like. When applied to the electrode mixture layer, it can be applied directly onto the positive electrode mixture layer or the negative electrode mixture layer.
As a method of applying the solid electrolyte layer forming paste, the same method as the above-described method of applying the positive electrode mixture layer forming paste can be employed. In addition, the thickness of the coating layer of the solid electrolyte layer-forming paste can be appropriately selected according to the purpose.

As a method for drying the applied layer of the paste for forming the solid electrolyte layer, the same method as the method for drying the applied layer of the paste for forming the positive electrode mixture layer described above can be employed. Further, the thickness of the solid electrolyte layer formed by this step is preferably in the range of 0.01 μm to 1000 μm, and more preferably in the range of 0.1 μm to 200 μm.

The method for manufacturing the solid electrolyte layer in the present embodiment may have arbitrary steps in addition to the steps described above. Examples of such a process include a compression process. By having a compression step, a high-density solid electrolyte layer can be obtained, and an increase in capacity can be achieved by improving ion conductivity and thinning the solid electrolyte layer.

(Non-aqueous electrolyte)
A known non-aqueous electrolyte may be appropriately used together with the solid electrolyte. The non-aqueous electrolyte can be interposed between at least one of the solid electrolyte layer and the negative electrode and between the solid electrolyte layer and the positive electrode, and exists in a state of being contained in any one of the positive electrode, the negative electrode, and the solid electrolyte layer. You may The non-aqueous electrolyte contains a non-aqueous solvent and an electrolyte salt dissolved in this non-aqueous solvent.

The non-aqueous solvent can be appropriately selected from known non-aqueous solvents. Non-aqueous solvents include cyclic carbonates, chain carbonates, carboxylic acid esters, phosphoric acid esters, sulfonic acid esters, ethers, amides, nitriles and the like. As the non-aqueous solvent, those in which some of the hydrogen atoms contained in these compounds are substituted with halogens may be used.

Cyclic carbonates include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), vinylethylene carbonate (VEC), chloroethylene carbonate, fluoroethylene carbonate (FEC), and difluoroethylene carbonate. (DFEC), styrene carbonate, 1-phenylvinylene carbonate, 1,2-diphenylvinylene carbonate and the like. Among these, EC is preferred.

Chain carbonates include diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diphenyl carbonate, trifluoroethylmethyl carbonate, bis(trifluoroethyl) carbonate and the like. Among these, EMC is preferred.

As the non-aqueous solvent, it is preferable to use a cyclic carbonate or a chain carbonate, and it is more preferable to use a combination of a cyclic carbonate and a chain carbonate. By using a cyclic carbonate, it is possible to promote the dissociation of the electrolyte salt and improve the ionic conductivity of the non-aqueous electrolyte. By using a chain carbonate, the viscosity of the non-aqueous electrolyte can be kept low. When a cyclic carbonate and a chain carbonate are used together, the volume ratio of the cyclic carbonate to the chain carbonate (cyclic carbonate:chain carbonate) is preferably in the range of, for example, 5:95 to 50:50.

The electrolyte salt can be appropriately selected from known electrolyte salts. Examples of electrolyte salts include lithium salts, sodium salts, potassium salts, magnesium salts, onium salts and the like. Among these, lithium salts are preferred.

Lithium salts include inorganic lithium salts such as LiPF ₆ , LiPO ₂ F ₂ , LiBF ₄ , LiClO ₄ and LiN(SO ₂ F) ₂ , lithium bis(oxalate) borate (LiBOB), lithium difluorooxalate borate (LiFOB). , lithium oxalate salts _such as lithium bis ₍ oxalate) difluorophosphate (LiFOP), _LiSO3CF3 , LiN( _SO2CF3 ) _{2 ,} LiN _{( SO2C2F5 ) 2} , LiN( _SO2CF3 ) (SO ₂ C ₄ F ₉ ), LiC(SO ₂ CF ₃ ) ₃ , LiC(SO ₂ C ₂ F ₅ ) ₃ and other lithium salts having a halogenated hydrocarbon group. Among these, inorganic lithium salts are preferred, and _LiPF6 is more preferred.

The content of the electrolyte salt in the non-aqueous electrolyte is preferably 0.1 mol/dm3 ^or more and 2.5 mol/dm3 or less, and 0.3 mol/ ^{dm3 or} more and 2.0 mol/dm3 or less at 20°C and 1 atm. It is more preferably ³ or less, more preferably 0.5 mol/dm ³ or more and 1.7 mol/dm ³ or less, and particularly preferably 0.7 mol/dm ³ or more and 1.5 mol/dm ³ or less. By setting the content of the electrolyte salt within the above range, the ionic conductivity of the non-aqueous electrolyte can be increased.

<Structure of Solid Battery>
The shape of the solid-state battery of this embodiment is not particularly limited, and examples thereof include a cylindrical battery, a square battery, a flat battery, a coin battery, and a button battery.
FIG. 9 shows a solid battery 1 as an example of a square battery. In addition, the same figure is taken as the figure which saw through the inside of a container. An electrode body 2 having a positive electrode and a negative electrode laminated with a solid electrolyte layer sandwiched therebetween is housed in a rectangular container 3 . The positive electrode is electrically connected to the positive electrode terminal 4 via a positive electrode lead 41 . The negative electrode is electrically connected to the negative terminal 5 via a negative lead 51 .

<Configuration of power storage device>
The solid-state battery of the present embodiment is a power source for automobiles such as electric vehicles (EV), hybrid vehicles (HEV), and plug-in hybrid vehicles (PHEV), a power source for electronic devices such as personal computers and communication terminals, or a power source for power storage. For example, it can be mounted as a power storage unit (battery module) configured by assembling a plurality of non-aqueous electrolyte power storage elements 1 . In this case, the technology of the present invention may be applied to at least one solid-state battery included in the power storage unit.
FIG. 10 shows an example of a power storage device 30 in which power storage units 20 in which two or more electrically connected solid-state batteries 1 are assembled are further assembled. The power storage device 30 may include a bus bar (not shown) that electrically connects two or more solid-state batteries 1, a bus bar (not shown) that electrically connects two or more power storage units 20, and the like. The power storage unit 20 or power storage device 30 may include a state monitoring device (not shown) that monitors the state of one or more solid state batteries.

<Method for manufacturing solid-state battery>
A method for manufacturing the solid-state battery in the present embodiment can be appropriately selected from known methods. In the manufacturing method, for example, a positive electrode mixture layer is formed by the above-described positive electrode manufacturing method, a negative electrode mixture layer is formed by the negative electrode manufacturing method, a solid electrolyte layer is formed by the solid electrolyte layer manufacturing method, and a solid The method includes forming an electrode body by laminating or winding a positive electrode having a positive electrode mixture layer and a negative electrode having a negative electrode mixture layer with an electrolyte layer interposed therebetween.
Further, in the method for manufacturing a solid battery according to the present embodiment, after forming a positive electrode mixture layer, a solid electrolyte layer is formed on the positive electrode mixture layer, and a laminate of the positive electrode mixture layer and the solid electrolyte layer, A solid battery may be assembled using the separately formed negative electrode mixture layer, or conversely, after forming the negative electrode mixture layer, the solid electrolyte layer is formed on the negative electrode mixture layer, and the solid electrolyte layer is formed on the negative electrode mixture layer. A solid battery may be assembled using a laminate of a negative electrode mixture layer and a solid electrolyte layer and a separately formed positive electrode mixture layer.
The above-described embodiment may be applied to at least one step of forming the positive electrode mixture layer, forming the negative electrode mixture layer, and forming the solid electrolyte layer, but it must be applied to all the steps. is preferred.

<Other embodiments>
The solid-state battery of the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the gist of the present invention. For example, the configuration of another embodiment can be added to the configuration of one embodiment, and part of the configuration of one embodiment can be replaced with the configuration of another embodiment or a known technique. Furthermore, some of the configurations of certain embodiments can be deleted. Also, well-known techniques can be added to the configuration of a certain embodiment.

EXAMPLES The present invention will be described in more detail below with reference to examples. The invention is not limited to the following examples.

[Example 1]
(Preparation of solid electrolyte)
As a halide solid electrolyte, Li ₃ YCl ₆ was produced as follows. YCl ₃ (purity 99.99%, manufactured by Aldrich) and LiCl (purity 99.998%, manufactured by Aldrich) were weighed in a glove box in an argon atmosphere with a dew point of −50° C. or less so as to obtain a predetermined molar ratio, A composition containing Li, Y, and Cl was prepared by mixing in a mortar. 0.8 g of the above composition was put into a sealed 80 mL zirconia pot containing about 700 zirconia balls with a diameter of 4 mm. A planetary ball mill (Premium line P-7, manufactured by FRITSCH) was used for 10 hours at a revolution speed of 510 rpm for mechanochemical treatment to obtain Li ₃ YCl ₆ .

(Evaluation of stability of solid electrolyte against organic solvent)
The stability of the resulting halide solid electrolyte against organic solvents was evaluated as follows.
As organic solvents, heptane, decane, tetralin, cumene, mesitylene, anisole, dibutyl ether, diisobutyl ketone, and butyl butyrate were prepared.
Each organic solvent was added dropwise until the halide solid electrolyte was immersed, and the mixture was stirred at 2000 rpm for 1 minute using a rotation/revolution mixer (Awatori Mixer, manufactured by Thinky) to prepare a paste. The obtained paste was dried under normal pressure at 100° C. for 30 minutes and then vacuum heat dried at 100° C. for 30 minutes to obtain a sample powder for evaluating stability against organic solvents.
FIG. 1 shows a flow chart showing the procedure for obtaining a sample powder for evaluating the stability of a halide solid electrolyte in an organic solvent.
The sample powder obtained as described above was subjected to X-ray diffraction measurement under the conditions described above. The obtained powder X-ray diffraction pattern is shown in FIG. From this diffractogram, Rigaku's software PDXL was used to obtain calculated data by automatic _{reading .} The intensity of the diffraction peak of LiCl at ±0.6° was read, and the intensity ratio I(LiCl)/I(Li ₃ YCl ₆ ) of the diffraction peak of LiCl to the diffraction peak of Li ₃ YCl ₆ was calculated.

(Measurement of ionic conductivity)
Regarding the sample powder obtained as described above, the ion conductivity was obtained by measuring the AC impedance as follows.
In an argon atmosphere with a dew point of −50° C. or less, 120 mg of the sample powder was placed in a powder molding machine with an inner diameter of 10 mm, and then uniaxially pressurized at a pressure of 50 MPa or less using a hydraulic press. After the pressure was released, 120 mg of SUS316L powder was put as a current collector on the upper surface of the sample, and then the hydraulic press was used again to carry out uniaxial pressure molding at a pressure of 50 MPa or less. Next, 120 mg of SUS316L powder as a current collector was added to the lower surface of the sample, and then uniaxial pressure molding was performed at a pressure of 360 MPa for 5 minutes to obtain pellets for ion conductivity measurement. This pellet for ion conductivity measurement was inserted into an HS cell (manufactured by Hosen), and AC impedance was measured at a predetermined temperature. The measurement conditions were an applied voltage amplitude of 20 mV, a frequency range of 1 MHz to 100 mHz, and a measurement temperature of 25°C.

Table 1 shows the intensity ratio I(LiCl)/I(Li ₃ YCl ₆ ) of the diffraction peaks of Example 1 and the ionic conductivity.

From FIG. 2 and Table 1, when the halide solid electrolyte is Li ₃ YCl ₆ , when diisobutyl ketone and butyl butyrate are used as the organic solvent, Li ₃ YCl ₆ is decomposed to form LiCl, and the ionic conductivity is reduced. In contrast, when heptane, decane, tetralin, cumene, mesitylene, anisole, or dibutyl ether is used as the organic solvent, the formation of LiCl due to the decomposition of Li ₃ YCl ₆ is suppressed, and the CuKα ray is reduced. Intensity ratio of the strongest diffraction peak of LiCl at 2θ = 30.0 ± 0.6° to the strongest diffraction peak derived from Li ₃ YCl ₆ at 2θ = 31.5 ± 0.5° in the powder X-ray diffractogram used It can be seen that I(LiCl)/I(Li ₃ YCl ₆ ) is 0.3 or less, and a solid electrolyte with high ionic conductivity can be obtained.
That is, when the halide solid electrolyte is Li ₃ YCl ₆ , aliphatic hydrocarbons (heptane, decane), cyclic organic compounds (tetralin, cumene, mesitylene, anisole), and long By using a chain ether (dibutyl ether) having two chain hydrocarbon groups, LiX (LiCl) for the strongest diffraction peak derived from the crystal structure of the halide solid electrolyte in the powder X-ray diffractogram using CuKα rays. It is possible to obtain a solid electrolyte layer or an electrode mixture layer, which is an applied layer of a paste using an organic solvent, in which the intensity ratio of the strongest diffraction peak is 0.3 or less. Here, LIX (LiCl) is LIX (LiCl) produced by decomposition of a halide solid electrolyte (Li ₃ YCl ₆ ) with an organic solvent.
When diisobutyl ketone or butyl butyrate is used as the organic solvent, a diffraction peak derived from LiCl is observed, but a diffraction peak derived from Li ₃ YCl ₆ is hardly observed. The intensity ratio of the LiCl diffraction peak to the derived diffraction peak could not be calculated.

[Example 2]
Li ₃ InCl ₆ was prepared as follows as a halide solid electrolyte. InCl ₃ (purity 99.999%, manufactured by Aldrich) and LiCl (purity 99.998%, manufactured by Aldrich) were weighed in a glove box in an argon atmosphere with a dew point of −50° C. or less so as to obtain a predetermined molar ratio, A composition containing Li, In, and Cl was prepared by mixing in a mortar. 0.8 g of the above composition was put into a sealed 80 mL zirconia pot containing about 700 zirconia balls with a diameter of 4 mm. A planetary ball mill (Premium line P-7, manufactured by FRITSCH) was used at a revolution speed of 510 rpm for 10 hours to obtain Li ₃ InCl ₆ by a mechanochemical process.
A sample powder for evaluating the stability of Li ₃ InCl ₆ to organic solvents was obtained in the same manner as in Example 1, except that decane, tetralin, dibutyl ether, and butyl butyrate were used as organic solvents.
A sample powder of Li ₃ InCl ₆ was subjected to X-ray diffraction measurement under the conditions described above. The obtained powder X-ray diffraction pattern is shown in FIG.
Also, in the same manner as in Example 1, the AC impedance was measured to obtain the ionic conductivity.

Table 2 shows the diffraction peak intensity ratio I(LiCl)/I(Li ₃ InCl ₆ ) and the ionic conductivity of Example 2.

From FIG. 3 and Table 2, when the halide solid electrolyte is Li ₃ InCl ₆ , when butyl butyrate is used as the organic solvent, Li ₃ InCl ₆ is decomposed to form LiCl, resulting in a significant decrease in ionic conductivity. In contrast, when decane, tetralin, or dibutyl ether is used as an organic solvent, the formation of LiCl due to the decomposition of Li ₃ InCl ₆ is suppressed, and 2θ = 34.5 ± The intensity ratio I(LiCl)/I(Li 3 InCl ₆ ) of the strongest diffraction peak of LiCl at 2θ=30.0±0.6° to the strongest diffraction peak derived from Li ₃ InCl ₆ at 0.5 _° is 0.3 or less, it can be seen that a solid electrolyte with high ionic conductivity can be obtained (when decane, tetralin, or dibutyl ether is used, the ionic conductivity is approximately the same as when no organic solvent is used).
That is, when the halide solid electrolyte is Li ₃ InCl ₆ , as in the case of Li ₃ YCl ₆ , an aliphatic hydrocarbon (decane), a cyclic organic compound (tetralin), and a By using a chain ether (dibutyl ether) having two long-chain hydrocarbon groups, LiX (LiCl) for the strongest diffraction peak derived from the crystal structure of the halide solid electrolyte in the powder X-ray diffractogram using CuKα rays. It is possible to obtain a solid electrolyte layer or an electrode mixture layer, which is an applied layer of a paste using an organic solvent, in which the intensity ratio of the strongest diffraction peak of is 0.3 or less. Here, LiX (LiCl) is LiX (LiCl) produced by decomposition of a halide solid electrolyte (Li ₃ InCl ₆ ) with an organic solvent.
When decane, tetralin, or dibutyl ether is used as an organic solvent, a diffraction peak is observed near 2θ of 30°. Since a similar diffraction peak is observed around °, this is a diffraction peak derived from Li ₃ InCl ₆ . Therefore, the intensity ratio I( _LiCl )/I ₍ When calculating Li ₃ InCl ₆ ), the diffraction peak near 2θ of 30° is not included in I(LiCl).
In contrast, when butyl butyrate is used, the diffraction peak near 2θ of 30° is more than twice the diffraction peak observed in the as-synthesized halide solid electrolyte before immersion in the solvent. Therefore, it can be said that LiCl produced by decomposition of Li ₃ InCl ₆ is present.

[Example 3]
As a halide solid electrolyte, Li ₂ ZrCl ₆ was prepared as follows. ZrCl ₄ (purity 99.99%, manufactured by Aldrich) and LiCl (purity 99.998%, manufactured by Aldrich) were weighed in a glove box in an argon atmosphere with a dew point of −50° C. or lower so as to obtain a predetermined molar ratio, A composition containing Li, Zr, and Cl was prepared by mixing in a mortar. 0.8 g of the above composition was put into a sealed 80 mL zirconia pot containing about 700 zirconia balls with a diameter of 4 mm. Mechanochemical treatment was performed for 10 hours at a revolution speed of 510 rpm using a planetary ball mill (Premium line P-7, manufactured by FRITSCH) to obtain Li ₂ ZrCl ₆ .
A sample powder for evaluating the stability of Li ₂ ZrCl ₆ to organic solvents was obtained in the same manner as in Example 1, except that decane, tetralin, and butyl butyrate were used as organic solvents.
The sample powder of Li ₂ ZrCl ₆ was subjected to X-ray diffraction measurement under the conditions described above. The obtained powder X-ray diffraction pattern is shown in FIG.
Also, in the same manner as in Example 1, the AC impedance was measured to obtain the ionic conductivity.

Table 3 shows the diffraction peak intensity ratio I(LiCl)/I(Li ₂ ZrCl ₆ ) and the ionic conductivity of Example 3.

From FIG. 4 and Table 3, when the halide solid electrolyte is Li ₂ ZrCl ₆ , when butyl butyrate is used as the organic solvent, Li ₂ ZrCl ₆ is decomposed to form LiCl, resulting in a significant decrease in ionic conductivity. On the other hand, when decane or tetralin is used as the organic solvent, the formation of LiCl due to the decomposition of Li ₂ ZrCl ₆ is suppressed and 2θ=32.0°±0. The intensity ratio I(LiCl)/I(Li ₂ ZrCl ₆ ) of the strongest diffraction peak of LiCl at 2θ=30.0±0.6° to the strongest diffraction peak derived from Li ₂ ZrCl ₆ at 5° is 0.0. 3 or less, it can be seen that a solid electrolyte with high ionic conductivity can be obtained (when decane or tetralin is used, the ionic conductivity is about the same as when no organic solvent is used).
That is, when the halide solid electrolyte is Li ₂ ZrCl ₆ , similarly to the case of Li ₃ YCl ₆ , by using an aliphatic hydrocarbon (decane) and a cyclic organic compound (tetralin) as an organic solvent, CuKα ray The intensity ratio of the strongest diffraction peak of LiX (LiCl) to the strongest diffraction peak derived from the crystal structure of the halide solid electrolyte in the powder X-ray diffraction pattern using the organic solvent is 0.3 or less. A solid electrolyte layer or an electrode mixture layer, which is a coating layer, can be obtained. Here, LiX (LiCl) is LiX (LiCl) produced by decomposition of a halide solid electrolyte (Li ₂ ZrCl ₆ ) with an organic solvent.
When butyl butyrate is used as the organic solvent, a diffraction peak derived from LiCl is observed, but a diffraction peak derived from Li ₂ ZrCl ₆ is hardly observed, so diffraction derived from the crystal structure of the halide solid electrolyte The intensity ratio of the LiCl diffraction peak to peak could not be calculated.

[Example 4]
As _a halide solid _electrolyte , _{Li3.2Y0.8Mg0.2Cl6} was prepared as follows _. YCl ₃ (purity 99.99%, manufactured by Aldrich), LiCl (purity 99.998%, manufactured by Aldrich), and MgCl ₂ (purity 99.9%, manufactured by Aldrich) in an argon atmosphere glove box with a dew point of −50° C. or less ) were weighed to a predetermined molar ratio and mixed in a mortar to prepare a composition containing Li, Y, Mg and Cl. 0.8 g of the above composition was put into a sealed 80 mL zirconia pot containing about 700 zirconia balls with a diameter of 4 mm. A planetary ball mill (Premium line P-7, manufactured by FRITSCH) was used for 10 hours at a revolution speed of 510 rpm to obtain Li _3.2 Y _0.8 Mg _0.2 Cl ₆ by a mechanochemical method.
A sample powder for evaluating the stability of Li _3.2 Y _0.8 Mg _0.2 Cl ₆ in organic solvents was obtained in the same manner as in Example 1, except that decane, tetralin, and dibutyl ether were used as the organic solvent. rice field.
A sample powder of Li _3.2 Y _0.8 Mg _0.2 Cl ₆ was subjected to X-ray diffraction measurement under the conditions described above. The obtained powder X-ray diffraction pattern is shown in FIG.
Also, in the same manner as in Example 1, the AC impedance was measured to obtain the ionic conductivity.

Table 4 shows the diffraction peak intensity ratio I(LiCl)/I(Li _3.2 Y _0.8 Mg _0.2 Cl ₆ ) and the ionic conductivity of Example 4.

From FIG. 5 and Table 4, when the halide solid electrolyte is Li _3.2 Y _0.8 Mg _0.2 Cl ₆ , Li _3.2 Y _0.8 Li3.2Y0.8Mg0.2Cl with 2θ = 34.0 _± 0.5° in _a powder X _- ray diffraction pattern using CuKα rays was suppressed by suppressing the formation of LiCl by decomposition _{of Mg0.2Cl6} . I(LiCl)/I( _{Li 3.2} Y _0.8 Mg _0.2 Cl ₆ ) becomes 0.3 or less, and a solid electrolyte with high ionic conductivity can be obtained (when decane, tetralin, or dibutyl ether is used, the ionic conductivity is about the same as when no organic solvent is used). .
That is, when the halide solid electrolyte is Li _3.2 Y _0.8 Mg _0.2 Cl ₆ , as in the case of Li ₃ YCl ₆ , an aliphatic hydrocarbon (decane) and a cyclic organic compound ( Tetralin), and a chain ether (dibutyl ether) having two long-chain hydrocarbon groups with 4 or more carbon atoms, derived from the crystal structure of the halide solid electrolyte in a powder X-ray diffraction diagram using CuKα rays It is possible to obtain a solid electrolyte layer or an electrode mixture layer, which is a paste coating layer using an organic solvent, in which the intensity ratio of the strongest diffraction peak of LiX (LiCl) to the strongest diffraction peak of LiX (LiCl) is 0.3 or less. .

[Example 5]
As a halide _{solid electrolyte} , _{Li3.2Y0.8Ca0.2Cl6} was prepared as follows _. YCl ₃ (purity 99.99%, manufactured by Aldrich), LiCl (purity 99.998%, manufactured by Aldrich), and CaCl ₂ (purity 99.99%, manufactured by Aldrich) in an argon atmosphere glove box with a dew point of −50° C. or less ) were weighed to a predetermined molar ratio and mixed in a mortar to prepare a composition containing Li, Y, Ca and Cl. 0.8 g of the above composition was put into a sealed 80 mL zirconia pot containing about 700 zirconia balls with a diameter of 4 mm. A planetary ball mill (Premium line P-7, manufactured by FRITSCH) was used at a revolution speed of 510 rpm for 10 hours to obtain Li _3.2 Y _0.8 Ca _0.2 Cl ₆ by a mechanochemical method.
A sample powder for evaluating the stability of Li _3.2 Y _0.8 Ca _0.2 Cl ₆ in organic solvents was obtained in the same manner as in Example 1, except that decane, tetralin, and dibutyl ether were used as the organic solvent. rice field.
A sample powder of Li _3.2 Y _0.8 Ca _0.2 Cl ₆ was subjected to X-ray diffraction measurement under the conditions described above. The obtained powder X-ray diffraction pattern is shown in FIG.
Also, in the same manner as in Example 1, the AC impedance was measured to obtain the ionic conductivity.

The ionic conductivity of Example 5 is shown in Table 5.

From FIG. 6 and Table 5, when the halide solid electrolyte is Li _3.2 Y _0.8 Ca _0.2 Cl ₆ , when decane, tetralin, and dibutyl ether are used as the organic solvent, X-ray powder diffraction using CuKα rays In the figure, diffraction peaks at 2θ near 30°, 31°, 35°, and 50° are present in the same manner as before immersion in the organic solvent, indicating that Li _3.2 Y _0.8 Ca _0.2 Cl ₆ It can be seen that the formation of LiCl due to decomposition was suppressed, and the crystal structure and ionic conductivity were maintained even after immersion in the organic solvent.
As shown in FIG. 6, Li _3.2 Y _0.8 Ca _0.2 Cl ₆ has a diffraction peak at the same position as the strongest diffraction peak of LiCl (2θ=30.0±0.6°). , the intensity ratio I(LiCl)/I(Li _3.2 Y _0.8 Ca _0.2 Cl ₆ ) could not be calculated.
However, the diffraction peak at 2θ = 30.0 ± 0.6 ° in the powder X-ray diffraction pattern using CuKα rays increased substantially after immersion in decane, tetralin, and dibutyl ether compared to before immersion in organic solvent. Therefore, this diffraction peak is derived from Li _3.2 Y _0.8 Ca _0.2 Cl ₆ , which is produced by decomposition of Li _3.2 Y _0.8 Ca _0.2 Cl ₆ It can be said that there are few substances derived from LiCl. Therefore, the strongest diffraction peak at 2θ = 30.0 ± 0.6° derived from LiCl relative to the strongest diffraction peak around 2θ = 31° derived from Li _3.2 Y _0.8 Ca _0.2 Cl ₆ There is _a high probability that the intensity ratio I(LiCl)/ _I ( _{Li3.2Y0.8Ca0.2Cl6} ) is 0.3 or _less .

[Example 6]
As a halide solid electrolyte, Li ₃ Y _0.8 Fe _0.2 Cl ₆ was produced as follows. YCl ₃ (purity 99.99%, manufactured by Aldrich), LiCl (purity 99.998%, manufactured by Aldrich), and FeCl ₃ (purity 99.9%, manufactured by Aldrich) in an argon atmosphere glove box with a dew point of −50° C. or less ) were weighed to a predetermined molar ratio and mixed in a mortar to prepare a composition containing Li, Y, Fe and Cl. 0.8 g of the above composition was put into a sealed 80 mL zirconia pot containing about 700 zirconia balls with a diameter of 4 mm. Mechanochemical treatment was performed for 10 hours at a revolution speed of 510 rpm using a planetary ball mill (Premium line P-7, manufactured by FRITSCH) to obtain Li ₃ Y _0.8 Fe _0.2 Cl ₆ .
A sample powder for evaluating the stability of Li ₃ Y _0.8 Fe _0.2 Cl ₆ to organic solvents was obtained in the same manner as in Example 1, except that decane, tetralin, and dibutyl ether were used as the organic solvent.
A sample powder of Li ₃ Y _0.8 Fe _0.2 Cl ₆ was subjected to X-ray diffraction measurement under the conditions described above. The obtained powder X-ray diffraction pattern is shown in FIG.
Also, in the same manner as in Example 1, the AC impedance was measured to obtain the ionic conductivity.

The ionic conductivity of Example 6 is shown in Table 6.

From FIG. 7 and Table 6, when the halide solid electrolyte is Li ₃ Y _0.8 Fe _0.2 Cl ₆ and decane, tetralin, and dibutyl ether are used as the organic solvent, the powder X-ray diffraction pattern using CuKα rays shows , 2θ near 30°, near 31.5°, near 35°, and near 50° exist in the same way as before immersion in the organic solvent, so that Li _3.2 Y _0.8 Ca _0.2 Cl ₆ It can be seen that the formation of LiCl due to decomposition is suppressed and the crystal structure is maintained even after immersion in the organic solvent. The ionic conductivity is maintained after immersion in organic solvents, except for dibutyl ether.
As shown in FIG. 7, Li ₃ Y _0.8 Fe _0.2 Cl ₆ has a diffraction peak at the same position as the strongest diffraction peak of LiCl (2θ=30.0±0.6°). Therefore, the intensity ratio I(LiCl)/I(Li ₃ Y _0.8 Fe _0.2 Cl ₆ ) could not be calculated.
However, the diffraction peak at 2θ = 30.0 ± 0.6 ° in the powder X-ray diffraction pattern using CuKα rays increased substantially after immersion in decane, tetralin, and dibutyl ether compared to before immersion in organic solvent. Therefore, this diffraction peak is derived from Li _3.2 Y _0.8 Fe _0.2 Cl ₆ , which is produced by decomposition of Li _3.2 Y _0.8 Fe _0.2 Cl ₆ It can be said that there are few substances derived from LiCl. Therefore, _the strongest diffraction peak at 2θ = 30.0 ± 0.6° derived from Li _3.2 Y _0.8 Fe _0.2 Cl There is a high probability that the intensity ratio I(LiCl)/I(Li _3.2 Y _0.8 Fe _0.2 Cl ₆ ) of the strongest diffraction peak is 0.3 or less.

[Example 7]
An example of a solid battery in which a paste coating layer using a halide solid electrolyte and an organic solvent is applied to the positive electrode mixture layer is shown.
(Production of solid battery)
LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (NCM523) was prepared as a positive electrode active material.
As solid electrolytes, two mixed solid electrolytes of a halide solid electrolyte Li ₃ YCl ₆ and a sulfide solid electrolyte Li ₆ PS ₅ Cl were prepared.
As a conductive agent, VGCF (registered trademark: manufactured by Showa Denko) was prepared.
Styrene-butadiene rubber (SBR) was prepared as a binder.
NCM523, Li ₃ YCl ₆ , Li ₆ PS ₅ Cl, VGCF, and SBR were mixed in an argon atmosphere glove box with a dew point of −50° C. or less. The mass ratio of the halide solid electrolyte and the sulfide solid electrolyte was 1:4. This mixture was kneaded with decane, which is an organic solvent, to prepare a paste for forming a positive electrode mixture layer. The obtained positive electrode mixture forming paste was applied on an aluminum foil (average thickness of 20 μm) as a positive electrode substrate, and the organic solvent was dried using a YBA baker applicator ^{. 2} or more and 25 mg·cm ⁻² or less. This was dried in an argon atmosphere dryer at 100° C. under normal pressure for 10 minutes and then under reduced pressure for 10 minutes to form a positive electrode material mixture layer on the positive electrode substrate. This was punched into a circle with a diameter of 10 mm to obtain a positive electrode for evaluation.
A positive electrode material mixture layer forming paste using butyl butyrate instead of decane as an organic solvent was applied to a positive electrode substrate and dried to prepare a positive electrode in the same manner.

Next, 80 mg of a sulfide solid electrolyte (Li ₆ PS ₅ Cl) was put into a ceramic powder molding machine with an inner diameter of 10 mm, and uniaxial pressure molding was performed using a hydraulic press at a pressure of 100 MPa for several seconds to form a solid electrolyte layer. formed. After releasing the pressure, the prepared positive electrode was placed on one side of the solid electrolyte layer, and bonded by uniaxial pressure molding at a pressure of 360 MPa for 5 minutes. After releasing the pressure, an indium foil (average thickness of 300 μm, diameter of 8 mm, manufactured by Nilaco) and a lithium foil (average thickness of 300 μm, diameter of 6 mm, manufactured by Honjo Metal) were applied to the surface opposite to the bonding surface of the positive electrode. A SUS316 foil (manufactured by The Nilaco Corporation) was added as a negative electrode base material, and bonded by uniaxial pressure molding at a pressure of 50 MPa for several seconds. A solid battery was obtained by removing this from the ceramic powder molding machine.

(Coulomb efficiency, resistance measurement)
An initial charge/discharge test was performed on each of the obtained solid-state batteries in the following manner.
Constant-current and constant-voltage charging was performed at 80° C. with a charging current of 0.1 C and a charge termination voltage of 3.75 V. The charging termination condition was until the charging current reached 0.025C. A rest period of 10 minutes was then provided. After charging, an AC impedance measurement was performed at 50°C. The measurement conditions were an applied voltage amplitude of 5 mV, a frequency range of 1 MHz to 10 mHz, and a measurement temperature of 50°C. Thereafter, constant current discharge was performed at 80° C. with a discharge current of 0.1 C and a discharge final voltage of 2.25 V. A rest period of 10 minutes was then provided.
The charge quantity of electricity in the initial charge and discharge, the discharge capacity, the coulombic efficiency which is the ratio of the discharge capacity to the charge quantity of charge in the initial charge and discharge, and the resistance value at 10 ³ Hz in the AC impedance measurement were obtained. FIG. 8 shows the results and the charge/discharge curves in the initial charge/discharge.

From FIG. 8 , when the positive electrode mixture layer contains Li ₃ YCl ₆ as a halide solid electrolyte, the solid battery having the positive electrode mixture layer, which is a paste coating layer containing decane as an organic solvent, has a higher organic solvent It can be seen that the discharge capacity is larger and the coulombic efficiency is higher than that of the solid battery having the positive electrode mixture layer, which is the applied layer of the paste containing butyl butyrate. The resistance value after the first charge is significantly smaller when decane is used as the organic solvent than when _{butyl butyrate} is used. It is thought that a positive electrode mixture layer with a high

According to the paste according to one aspect of the present invention, and the solid electrolyte layer or electrode mixture layer that is the coating layer of this paste, the decomposition of the halide solid electrolyte to produce lithium halide is suppressed, and the ionic conductivity It is possible to provide a solid battery having a solid electrolyte layer or an electrode mixture layer with a high . This is useful as a solid-state battery for hybrid vehicles, plug-in hybrid vehicles, and electric vehicles.

1 solid battery 2 electrode body 3 container 4 positive electrode terminal 41 positive electrode lead 5 negative electrode terminal 51 negative electrode lead 20 power storage unit 30 power storage device

Claims (13)

It contains a halide solid electrolyte and an organic solvent, and the halide solid electrolyte contains Li, M and X (wherein M is at least one selected from the group consisting of metal elements and metalloid elements other than Li, X is At least one selected from the group consisting of F, Cl, Br, and I), and the organic solvent includes an aliphatic hydrocarbon, a cyclic organic compound, and a compound having 4 or more carbon atoms. A paste containing at least one selected from chain ethers having two long-chain hydrocarbon groups and cyclic ethers. 2. The paste of claim 1, wherein M of the halide is an element from Groups 2 to 15 of the Periodic Table. 3. The paste according to claim 2, wherein the halide M is one or more selected from the group consisting of Y, In, Zr, Mg, Ca, and Fe. The paste according to claim 1, wherein the organic solvent contains an aliphatic hydrocarbon, and the aliphatic hydrocarbon has a long-chain hydrocarbon group with 7 or more carbon atoms. The paste according to claim 4, wherein the aliphatic hydrocarbon is one or more selected from heptane and decane. The paste according to claim 1, wherein the organic solvent comprises a cyclic organic compound, and the cyclic organic compound is an aromatic compound. 7. The paste according to claim 6, wherein the aromatic compound is one or more selected from the group consisting of tetralin, cumene, mesitylene, and anisole. The organic solvent includes a chain ether having two long-chain hydrocarbon groups having 4 or more carbon atoms or a cyclic ether, and the chain ether having two long-chain hydrocarbon groups having 4 or more carbon atoms is , dibutyl ether, dipentyl ether, the cyclic ether is one or more selected from the group consisting of tetrahydrofuran. A solid electrolyte layer or an electrode mixture layer, which is a coating layer of the paste according to any one of claims 1 to 8. A solid battery comprising the solid electrolyte layer or electrode mixture layer according to claim 9 . Li, M and X (wherein M is at least one selected from the group consisting of metal elements and metalloid elements other than Li, X is at least one selected from the group consisting of F, Cl, Br, and I ) and the strongest diffraction peak of LiX relative to the strongest diffraction peak derived from the crystal structure of the halide solid electrolyte in a powder X-ray diffraction diagram using CuKα rays A solid electrolyte layer or an electrode mixture layer having a strength ratio of 0.3 or less. 12. The solid electrolyte layer or electrode mixture layer according to claim 11, wherein M of said halide is one or more selected from the group consisting of Y, In, Zr, Mg, Ca and Fe. A solid battery comprising the solid electrolyte layer or electrode mixture layer according to claim 11 or 12.

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