WO2024162294A1

WO2024162294A1 - Modified sulfide solid electrolyte producing method, said modified sulfide solid electrolyte, and electrode mixture and lithium-ion battery containing said modified sulfide solid electrolyte

Info

Publication number: WO2024162294A1
Application number: PCT/JP2024/002743
Authority: WO
Inventors: 祥悟門田; 淳佐藤
Original assignee: 出光興産株式会社
Priority date: 2023-01-31
Filing date: 2024-01-30
Publication date: 2024-08-08

Abstract

Provided are: a modified sulfide solid electrolyte producing method that includes heating an oxide and a sulfide solid electrolyte having an argyrodite crystal structure at 300-600°C; said modified sulfide solid electrolyte; and an electrode mixture and a lithium-ion battery which contain said modified sulfide solid electrolyte.

Description

Method for producing modified sulfide solid electrolyte, modified sulfide solid electrolyte, and electrode mixture and lithium ion battery containing modified sulfide solid electrolyte

The present invention relates to a method for producing a modified sulfide solid electrolyte, a modified sulfide solid electrolyte, an electrode mixture, and a lithium ion battery.

In recent years, with the rapid spread of information-related devices and communication devices such as personal computers, video cameras, and mobile phones, the development of batteries to be used as power sources for these devices has become important. Traditionally, batteries used for such purposes used electrolytes containing flammable organic solvents, but by making the battery fully solid-state, flammable organic solvents are not used in the battery, safety devices can be simplified, and manufacturing costs and productivity are excellent, so batteries in which the electrolyte is replaced with a solid electrolyte layer are being developed.

　Sulfide solid electrolytes have been known for some time as solid electrolytes used in solid electrolyte layers. Although sulfide solid electrolytes have high ionic conductivity, they can be affected by moisture in the atmosphere and generate hydrogen sulfide. Therefore, there is a need to develop a sulfide solid electrolyte that suppresses the generation of hydrogen sulfide while maintaining ionic conductivity.

It is known to add an oxide to a sulfide solid electrolyte.
For example, Patent Document 1 discloses a method of adding oxides such as Al ₂ O ₃ and SiO ₂ to glass ceramics and incorporating them into the crystal structure to increase the crystallinity of the high lithium ion conductive phase and improve the ion conductivity.

Patent Document 2 discloses that SiO ₂ is incorporated into the crystal structure of a sulfide solid electrolyte to form an amorphous-like crystal, improving the state of the crystal interface and reducing grain boundary resistance.
Patent Document 3 discloses that inexpensive α-alumina is incorporated into an inorganic solid electrolyte to obtain an inexpensive solid electrolyte while maintaining ionic conductivity.

Patent Document 4 discloses that by incorporating alumina into the crystal structure of a sulfide solid electrolyte, aggregation of particles of a lithium ion conductive material is less likely to occur and the dispersibility of the particles is improved, resulting in the formation of uniform ion conductivity paths in all directions and improved ion conductivity.
Patent Document 5 studies the improvement of lithium ion conductivity in a sulfide solid electrolyte having an argyrodite-type crystal structure, and Patent Document 6 studies the fact that a sulfide solid electrolyte having an argyrodite-type crystal structure remains stable without decomposition even when subjected to heat treatment at high temperatures.

JP 2015-076316 A JP 2012-022801 A JP 2012-190553 A WO2020/105604 Brochure WO2022/009934 Brochure WO2022/009935 Brochure

The present invention has been made in consideration of these circumstances, and aims to provide a method for producing a modified sulfide solid electrolyte that can obtain a modified sulfide solid electrolyte in which hydrogen sulfide generation is suppressed while maintaining the ionic conductivity of the sulfide solid electrolyte, to provide the modified sulfide solid electrolyte, and to provide an electrode mixture and a lithium ion battery that include the modified sulfide solid electrolyte.

The method for producing a modified sulfide solid electrolyte according to the present invention includes heating a sulfide solid electrolyte having an argyrodite-type crystal structure and an oxide at 300° C. or more and 600° C. or less.
The modified sulfide solid electrolyte according to the present invention includes a sulfide solid electrolyte having an argyrodite-type crystal structure containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and an oxide represented by the general formula M _m O _n (wherein M represents an atom selected from Mg, Al, Si, Ca, Ti, V, Fe, Zn, Ga, Sr, Y, Zr, Nb, Mo, Sn, Sb, Ba, Ta, W, and Bi, and m and n each independently represent an integer of 1 to 5), and satisfies the following (i) to (iii).
(i) At least one oxide in which M in the general formula M _m O _n is Al is included.
(ii) the ratio (M M /M _P ) of the total number of moles of M in all oxides contained in the modified sulfide solid electrolyte (M _M ) to the total number of moles of phosphorus atoms in the sulfide solid electrolyte ( _M _P ) is greater than 0.010.
(iii) Only one peak is observed within the range of 29.7±0.5 deg. in an X-ray diffraction spectrum (XRD pattern), or when two or more peaks are observed, _I2 / _I1 is less than 1.0, where _I1 is the intensity of the highest peak and _I2 is the intensity of the second highest peak.
The electrode mixture according to the present invention is an electrode mixture comprising the modified sulfide solid electrolyte and an electrode active material.
The lithium ion battery according to the present invention is a lithium ion battery including at least one of the modified sulfide solid electrolyte and the electrode mixture.

The present invention provides a method for producing a modified sulfide solid electrolyte that can obtain a modified sulfide solid electrolyte in which hydrogen sulfide generation is suppressed while maintaining the ionic conductivity of the sulfide solid electrolyte, provides the modified sulfide solid electrolyte, and provides an electrode mixture and a lithium ion battery that include the modified sulfide solid electrolyte.

FIG. 2 is a flow diagram illustrating an example of a preferred embodiment of the method for producing a modified sulfide solid electrolyte according to the present embodiment. 1 is an example of a device for measuring the amount of hydrogen sulfide generated. 1 is a graph showing the change over time in the integrated generation amount and instantaneous generation amount of hydrogen sulfide for the modified sulfide solid electrolyte (5), the modified sulfide solid electrolyte (C6), and the modified sulfide solid electrolyte (C8). 1 shows XRD patterns of modified sulfide solid electrolyte (5), modified sulfide solid electrolyte (C6) and modified sulfide solid electrolyte (C8).

Below, an embodiment of the present invention (hereinafter, sometimes referred to as "this embodiment") will be described. Note that in this disclosure, the upper and lower limit values of the numerical ranges "greater than or equal to," "less than or equal to," and "to" are values that can be combined in any way, and the numerical values in the examples can also be used as the upper and lower limit values. Furthermore, provisions that are considered to be preferred can be adopted in any way. In other words, one provision that is considered to be preferred can be adopted in combination with one or more other provisions that are considered to be preferred. It can be said that a combination of preferred things is more preferable.

(Findings the inventor has acquired to arrive at the present invention)
As a result of intensive research aimed at solving the above problems, the present inventors have discovered the following and have completed the present invention.
The inventions described in the above Patent Documents 1 to 3 do not relate to a sulfide solid electrolyte having an argyrodite-type crystal structure, and do not consider suppressing the generation of hydrogen sulfide from a sulfide solid electrolyte. In addition, since the purpose is not to modify the sulfide solid electrolyte, the sulfide solid electrolyte and the oxide are not treated at a sufficient temperature. For this reason, it is considered that the sulfide solid electrolyte and the oxide are not contained in the modified sulfide solid electrolyte of the present invention, as described below.

Patent Document 4 examines a sulfide solid electrolyte with an argyrodite-type crystal structure, but this differs from the present invention in that the sulfide solid electrolyte is modified. Furthermore, since the sulfide solid electrolyte and oxide are not treated at a sufficient temperature, it is believed that the sulfide solid electrolyte does not contain the sulfide solid electrolyte and oxide as described below, as in the modified sulfide solid electrolyte of the present invention.

Patent Documents

5 and 6 discuss a sulfide solid electrolyte having an argyrodite crystal structure. However, in the inventions described in

Patent Documents

5 and 6, the sulfide solid electrolyte and an oxide are treated at a high temperature of 650° C., so that, for example, in SiO ₂ , all four oxygen atoms bonded to Si become non-bridging oxygen atoms, and become oxide anions of a Q0 structure in the form of silicate ions SiO ₄ ^4- , and are completely incorporated into the argyrodite crystal structure. For this reason, it is different from the present invention, which includes a sulfide solid electrolyte and an oxide as described below. Furthermore,

Patent Documents

5 and 6 do not discuss at all the suppression of hydrogen sulfide generation. In particular, Patent Document 6 adds an oxide so that the sulfide solid electrolyte can withstand high-temperature treatment in order to effectively reduce grain boundary resistance by sintering, and the problem to be solved is significantly different from that of the present invention. Thus, in

Patent Documents

5 and 6, the composition of the sulfide solid electrolyte itself changes and the average particle size of the sulfide solid electrolyte also increases by treating the sulfide solid electrolyte at a high temperature of 650° C.

In contrast, the method for producing a modified sulfide solid electrolyte of the present invention is a method for producing a modified sulfide solid electrolyte that includes heating the sulfide solid electrolyte described below and the oxide described below as described below. This makes it possible to provide a method for producing a modified sulfide solid electrolyte that can obtain a modified sulfide solid electrolyte in which hydrogen sulfide generation is suppressed while maintaining the ionic conductivity of the sulfide solid electrolyte, to provide the modified sulfide solid electrolyte, and to provide an electrode mixture and a lithium ion battery that include the modified sulfide solid electrolyte.

The present inventors have found that it is possible to provide a method for producing a modified sulfide solid electrolyte, which can obtain a modified sulfide solid electrolyte in which generation of hydrogen sulfide is suppressed while maintaining the ionic conductivity of the sulfide solid electrolyte, by heating a sulfide solid electrolyte having an argyrodite-type crystal structure and an oxide within a specific temperature range.
In addition to the sulfide solid electrolyte exhibiting high ionic conductivity, it is desired to reduce the median diameter (D ₅₀ ) of the sulfide solid electrolyte depending on the application. The sulfide solid electrolyte can be used in the positive electrode, negative electrode, and solid electrolyte layer of an all-solid-state battery, and in the electrode (positive electrode, negative electrode), the sulfide solid electrolyte is used in combination with an electrode active material (positive electrode active material, negative electrode active material). Since the sulfide solid electrolyte and the electrode active material are both solid electrolytes, if the median diameter (D ₅₀ ) of the sulfide solid electrolyte can be reduced, it becomes easier to form a contact interface between the electrode active material and the sulfide solid electrolyte, and the paths of ionic conduction and electronic conduction become good. As a result, excellent battery performance can be obtained. Based on such knowledge, the present inventors have arrived at the following manufacturing method of this embodiment, the modified sulfide solid electrolyte, and the configuration of an electrode mixture and a lithium ion battery containing the modified sulfide solid electrolyte.
The manufacturing method of the present invention can be carried out using conventional manufacturing equipment and can be said to be excellent in productivity.

(Definition of terms)
In the present disclosure, a "solid electrolyte" refers to an electrolyte that maintains a solid state under a nitrogen atmosphere at 25° C. A "sulfide solid electrolyte" in the present disclosure is a solid electrolyte that contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms and has ionic conductivity due to lithium atoms.
In the present disclosure, the term "modified sulfide solid electrolyte" refers to a modified sulfide solid electrolyte obtained by the production method of the present embodiment, as described below.
In the present disclosure, "modification" refers to a state in which a sulfide solid electrolyte having an argyrodite-type crystal structure and an oxide are contained by a manufacturing method including heating the sulfide solid electrolyte having an argyrodite-type crystal structure and an oxide at 300°C or more and 600°C or less. "Containing" may mean that an oxide is present on the surface of a particulate sulfide solid electrolyte, and is a concept including that an oxide is attached to and bonded to the surface of the sulfide solid electrolyte. In other words, the modified sulfide solid electrolyte is a sulfide solid electrolyte that has been modified by containing an oxide. "Attachment" includes physical adsorption, and "bonding" includes chemical bonding and coordinate bonding.
In the present disclosure, the term "oxide" refers to an oxide containing a specific element, as described in detail below.

(Various aspects of the present embodiment)
The following describes the manufacturing methods for modified sulfide solid electrolytes according to the first to tenth aspects of this embodiment, the modified sulfide solid electrolytes according to the eleventh to eighteenth aspects, the electrode composite according to the nineteenth aspect, and the lithium ion battery according to the twentieth aspect.
The method for producing a modified sulfide solid electrolyte according to the first aspect of the present embodiment includes the steps of:
A method for producing a modified sulfide solid electrolyte includes heating a sulfide solid electrolyte having an argyrodite-type crystal structure and an oxide at 300° C. or more and 600° C. or less.

1 shows a flow diagram illustrating a preferred embodiment of the method for producing the modified sulfide solid electrolyte of this embodiment. The production method of this embodiment is useful because it is possible to obtain a modified sulfide solid electrolyte in which hydrogen sulfide generation is suppressed while suppressing an increase in the median diameter (D ₅₀ ) and maintaining the ionic conductivity of the sulfide solid electrolyte by heating a sulfide solid electrolyte having an argyrodite-type crystal structure and an easily available oxide within a specific temperature range. The obtained modified sulfide solid electrolyte has high ionic conductivity, so that a lithium ion battery with excellent battery performance can be obtained by using this modified sulfide solid electrolyte.

The method for producing a modified sulfide solid electrolyte according to a second aspect of the present embodiment is the same as the first aspect,
The sulfide solid electrolyte contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms.

It is preferable that the sulfide solid electrolyte contains the above-mentioned atoms, since this makes it possible to produce a modified sulfide solid electrolyte with high ionic conductivity.

The method for producing a modified sulfide solid electrolyte according to a third aspect of the present embodiment is the same as the method for producing a modified sulfide solid electrolyte according to the second aspect,
The method for producing a modified sulfide solid electrolyte includes, as the halogen atom, at least one selected from a chlorine atom and a bromine atom.

The modified sulfide solid electrolyte is preferred because it has a stable argyrodite-type crystal structure due to the inclusion of at least one selected from chlorine atoms and bromine atoms. The modified sulfide solid electrolyte having the argyrodite-type crystal structure is preferred because it maintains the ionic conductivity of the sulfide solid electrolyte, inhibits an increase in the median diameter ( _D50 ), and inhibits the generation of hydrogen sulfide.

The method for producing a modified sulfide solid electrolyte according to a fourth aspect of the present embodiment is any one of the first to third aspects,
The method for producing a modified sulfide solid electrolyte includes the oxide containing a compound represented by the general formula M _m O _n (wherein M represents an atom selected from Mg, Al, Si, Ca, Ti, V, Fe, Zn, Ga, Sr, Y, Zr, Nb, Mo, Sn, Sb, Ba, Ta, W, and Bi, and m and n each independently represent an integer of 1 to 5).

It is preferable that the oxide contains a compound represented by the general formula M _m O _n described later, because this makes it possible to obtain a modified sulfide solid electrolyte in which the ionic conductivity of the sulfide solid electrolyte is maintained, an increase in the median diameter (D ₅₀ ) is suppressed, and generation of hydrogen sulfide is suppressed.
The M may be an atom selected from Mg, Al, Si, Ca, Ti, V, Fe, Zn, Ga, Sr, Y, Zr, Nb, Mo, Sn, Sb, Ba, Ta, W, and Bi, and when m in the formula is 2 or more, it may contain two or more of the same atom (for example _, _Al2O3 ) or may contain two or more different types of atoms (for example, _CaTiO3 ).

The method for producing a modified sulfide solid electrolyte according to a fifth aspect of the present embodiment is the same as the method for producing a modified sulfide solid electrolyte according to the fourth aspect,
The present invention relates to a method for producing a modified sulfide solid electrolyte comprising an oxide in which M in the general formula M _m O _n is Al.

The oxide preferably contains aluminum oxide (Al ₂ O ₃ ), since the ionic conductivity of the modified sulfide solid electrolyte is increased and the generation of hydrogen sulfide is further suppressed while suppressing an increase in the median diameter (D ₅₀ ).

A method for producing a modified sulfide solid electrolyte according to a sixth aspect of the present embodiment comprises the steps of:
The method for producing a modified sulfide solid electrolyte is characterized in that a ratio (M _M /M _P ) of the total number of moles of M in the oxide (M _M ) to the total number of moles of phosphorus atoms in the sulfide solid electrolyte (M _P ) is greater than 0.010.

It is preferable that the M _M /M _P is greater than 0.010 because the effect of containing the oxide is increased. M _M and M _P can be calculated from the amounts of the sulfide solid electrolyte and oxide used in the production of the modified sulfide solid electrolyte.

A method for producing a modified sulfide solid electrolyte according to a seventh aspect of the present embodiment is any one of the first to sixth aspects,
The heating is carried out for one hour or more in this method for producing a modified sulfide solid electrolyte.

In the manufacturing methods described in

Patent Documents

5 and 6, heating is performed at 650° C., and the oxide is completely incorporated into the argyrodite-type crystal structure. In contrast, in the manufacturing method of the present embodiment, heating is performed at 300° C. or more and 600° C. or less, so that the oxide modifies the sulfide solid electrolyte, but the decrease in ion conductivity and the increase in median diameter (D ₅₀ ) are suppressed. Furthermore, the inclusion of the oxide, which will be described later, is preferable because it suppresses the generation of hydrogen sulfide.

The method for producing a modified sulfide solid electrolyte according to an eighth aspect of the present embodiment is any one of the first to seventh aspects,
and mixing the resulting mixture.

The method for producing the modified sulfide solid electrolyte of the present embodiment requires heating, but further includes mixing, which is preferable because it makes the sulfide solid electrolyte and oxide contained in the modified sulfide solid electrolyte uniform. Such uniform inclusion of the sulfide solid electrolyte and oxide can further suppress an increase in the median diameter ( _D50 ) and the generation of hydrogen sulfide.
The mixing may be performed while heating, before heating, or a combination of these. However, mixing before heating is preferable because the oxide is uniformly attached to the surface of the sulfide solid electrolyte, and when this is heated, it is uniformly contained on the surface of the sulfide solid electrolyte.

A method for producing a modified sulfide solid electrolyte according to a ninth aspect of the present embodiment is any one of the first to eighth aspects,
In the method for producing a modified sulfide solid electrolyte, the heating is performed by simultaneously heating the sulfide solid electrolyte and the oxide with one heater.

By simultaneously heating the sulfide solid electrolyte and the oxide with one heater, the oxide adheres uniformly to the surface of the sulfide solid electrolyte, and when this is heated, it is preferably uniformly contained on the surface of the sulfide solid electrolyte. By being uniformly contained in this way, the generation of hydrogen sulfide is further suppressed.

A method for producing a modified sulfide solid electrolyte according to a tenth aspect of the present embodiment is any one of the first to ninth aspects,
In the method for producing a modified sulfide solid electrolyte, the median diameter (D ₅₀ ) of the oxide attached to or bonded to the surface of a primary particle of the modified sulfide solid electrolyte is less than 100.0 μm.

When the median diameter (D ₅₀ ) of the oxide is less than 100.0 μm, a contact interface between the electrode active material and the modified sulfide solid electrolyte is easily formed, and paths for ionic conduction and electronic conduction are favorable, which is preferable.

The modified sulfide solid electrolyte according to the eleventh aspect of this embodiment is
a sulfide solid electrolyte having an argyrodite-type crystal structure containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms;
and an oxide represented by the general formula M _m O _n (wherein M represents an atom selected from Mg, Al, Si, Ca, Ti, V, Fe, Zn, Ga, Sr, Y, Zr, Nb, Mo, Sn, Sb, Ba, Ta, W and Bi, and m and n each independently represent an integer of 1 to 5),
The modified sulfide solid electrolyte satisfies the following (i) to (iii):
(i) At least one oxide in which M in the general formula M _m O _n is Al is included.
(ii) the ratio (M M /M _P ) of the total number of moles of M in all oxides contained in the modified sulfide solid electrolyte (M _M ) to the total number of moles of phosphorus atoms in the sulfide solid electrolyte ( _M _P ) is greater than 0.010.
(iii) Only one peak is observed within the range of 29.7±0.5 deg. in an X-ray diffraction spectrum (XRD pattern), or when two or more peaks are observed, _I2 / _I1 is less than 1.0, where _I1 is the intensity of the highest peak and _I2 is the intensity of the second highest peak.

Satisfying the above (i) means that the modified sulfide solid electrolyte contains an oxide, and satisfying (ii) means that the lower limit of the oxide content is specified by M _M /M _P. By satisfying these (i) and (ii), the modified sulfide solid electrolyte of the present embodiment is a modified sulfide solid electrolyte that can obtain a modified sulfide solid electrolyte in which the generation of hydrogen sulfide is suppressed while maintaining the ionic conductivity of the sulfide solid electrolyte. Furthermore, the above (iii) means that the modified sulfide solid electrolyte has an argyrodite-type crystal structure as a main structure. More specifically, it is considered to mean that the argyrodite-type crystal maintains its structure without being decomposed by mutual reaction with the oxide specified by (i) and (ii). As a result, the modified sulfide solid electrolyte has high ionic conductivity.

The modified sulfide solid electrolyte according to a twelfth aspect of the present embodiment is the modified sulfide solid electrolyte according to the eleventh aspect,
The modified sulfide solid electrolyte has an intensity ratio (peak intensity derived from oxide/peak intensity derived from Argyrodite-type crystal structure) of less than 0.1 between a peak intensity derived from the oxide and a peak intensity of 29.7±0.5 deg. derived from the Argyrodite-type crystal structure (the peak intensity of 29.7±0.5 deg. derived from the Argyrodite-type crystal structure is referred to as the peak intensity derived from the Argyrodite-type crystal structure in the explanation of the intensity ratio) in an X-ray diffraction spectrum (XRD pattern).

In addition to the eleventh aspect, when the intensity ratio is less than 0.1, the generation of hydrogen sulfide can be further suppressed while maintaining the ionic conductivity of the sulfide solid electrolyte, which is preferable.
In the modified sulfide solid electrolyte according to the eleventh aspect of the present embodiment, by satisfying the above (iii), the oxide is not incorporated into the crystal structure of the sulfide solid electrolyte, or even if an oxide is incorporated, the Argyrodite crystal structure is maintained, so that the peak intensity of 29.7 ± 0.5 deg. maintains the strength of the sulfide solid electrolyte. The intensity ratio (peak intensity derived from oxide/peak intensity derived from Argyrodite crystal structure) between the peak intensity derived from the oxide and the peak intensity of 29.7 ± 0.5 deg. derived from the Argyrodite crystal structure (peak intensity derived from Argyrodite crystal structure) is within a specific range, so that even if an oxide is present in the modified sulfide solid electrolyte, the oxide particles are small (hereinafter also referred to as nanoparticles. Nanoparticles mean that the particle diameter of the particles is on the nano order), and the crystallites are small enough to be undetectable by XRD. When the oxide is present as nanoparticles and the intensity ratio is less than 0.1, the formation of the contact interface by the oxide is not inhibited, the path of electronic conduction is improved, and further, the generation of hydrogen sulfide in the modified sulfide solid electrolyte is suppressed, which is preferable. In particular, when the oxide adheres to the surface of the primary particle of the sulfide solid electrolyte, the formation of secondary particles of the modified sulfide solid electrolyte is suppressed, which is preferable because an increase in the median diameter ( _D50 ) is unlikely to occur.

The modified sulfide solid electrolyte according to a thirteenth aspect of the present embodiment is the modified sulfide solid electrolyte according to the eleventh or twelfth aspect,
The modified sulfide solid electrolyte contains at least one halogen atom selected from a chlorine atom and a bromine atom.

The modified sulfide solid electrolyte according to a fourteenth aspect of the present embodiment is any one of the eleventh to thirteenth aspects,
The oxide is attached or bonded to the surface of the primary particles, forming a modified sulfide solid electrolyte.

The modified sulfide solid electrolyte of the present embodiment is required to contain the sulfide solid electrolyte and the oxide, and the oxide is preferably contained in the modified sulfide solid electrolyte in a state of being bound to the surface of the primary particles of the sulfide solid electrolyte. "Attached" and "bound" have the same meanings as described above.
The modified sulfide solid electrolyte in which the oxide is attached or bonded to the surface of the primary particles of the sulfide solid electrolyte is preferable because the oxide is not easily detached and the modified sulfide solid electrolyte is easy to maintain a stable composition and shape because the oxide is attached or bonded to the surface of the primary particles of the sulfide solid electrolyte. In addition, the oxide is attached or bonded to the surface of the primary particles of the sulfide solid electrolyte, which suppresses the formation of secondary particles in which primary particles are bonded to each other, thereby suppressing the increase in the median diameter (D ₅₀ ). In addition, the opportunity for contact of the sulfide solid electrolyte with water in the atmosphere can be reduced, which is preferable because the generation of hydrogen sulfide can be suppressed. In order to achieve these effects, it is more preferable that the oxide is bonded to the surface of the primary particles of the sulfide solid electrolyte.

The modified sulfide solid electrolyte according to a fifteenth aspect of the present embodiment is any one of the eleventh to fourteenth aspects,
The modified sulfide solid electrolyte has a median diameter (D ₅₀ ) of less than 150 μm.

When the median diameter ( _D50 ) of the modified sulfide solid electrolyte is small, a contact interface between the electrode active material and the sulfide solid electrolyte is easily formed, and the paths for ionic conduction and electronic conduction are improved. Therefore, the use of this modified sulfide solid electrolyte is preferable because it allows a lithium ion battery with excellent battery performance to be obtained.
The median diameter ( _D50 ) of the powder of the solid electrolyte such as the modified sulfide solid electrolyte and the sulfide solid electrolyte can be measured or calculated, for example, by the method described in the Examples. In addition, the particle size distribution of the solid electrolyte can be confirmed by measuring _D50 . A small particle size distribution is preferable because it makes it easier to manufacture the electrode mixture described below and also improves the paths of ion conduction and electron conduction.

The modified sulfide solid electrolyte according to a sixteenth aspect of the present embodiment is the same as the modified sulfide solid electrolyte according to the fourteenth or fifteenth aspect,
The modified sulfide solid electrolyte has a median diameter (D ₅₀ ) of the oxide attached to or bonded to the surface of the primary particles of less than 100.0 μm.

In the modified sulfide solid electrolyte of this embodiment, when the median diameter ( _D50 ) of the oxide attached or bonded to the surface of the primary particle of the sulfide solid electrolyte is less than 100.0 μm, the electrode mixture containing the modified sulfide solid electrolyte and the electrode active material is likely to form a contact interface between the electrode active material and the sulfide solid electrolyte, and the paths for ion conduction and electron conduction are improved, and the use of this modified sulfide solid electrolyte is preferable because a lithium ion battery with excellent battery performance can be obtained.
In particular, the embodiment in which the twelfth embodiment and this embodiment are combined is preferable because the oxide is not incorporated into the crystal structure of the sulfide solid electrolyte but is present in a state of being bonded to the surface of the primary particles of the sulfide solid electrolyte, and therefore the effect of suppressing the generation of hydrogen sulfide can be obtained while maintaining the ionic conductivity of the sulfide solid electrolyte. Also, as described above, this embodiment is preferable because the increase in the median diameter ( _D50 ) of the modified sulfide solid electrolyte is suppressed.

The modified sulfide solid electrolyte according to a seventeenth aspect of the present embodiment is any one of the eleventh to sixteenth aspects,
The modified sulfide solid electrolyte includes an oxide in which M in the general formula M _m O _n is Si.

The modified sulfide solid electrolyte of the present embodiment is required to contain at least one oxide in which M is Al in the general _formula _MmOn . However, it is preferable to further contain an oxide in which M is Si, because even if the content of the oxide in which M is Al is reduced, the generation of hydrogen sulfide is suppressed while maintaining ionic conductivity.

The modified sulfide solid electrolyte according to an eighteenth aspect of the present embodiment is any one of the eleventh to seventeenth aspects,
The modified sulfide solid electrolyte does not include an oxide in which M in the general formula M _m O _n is Ti.

The modified sulfide solid electrolyte of the present embodiment does not contain an oxide in which M in the general _formula _MmOn is Ti, which is preferable because it can further suppress the generation of hydrogen sulfide while maintaining the ionic conductivity of the sulfide solid electrolyte.

The electrode mixture according to the nineteenth aspect of this embodiment is
An electrode mixture comprising the modified sulfide solid electrolyte of any one of the eleventh to eighteenth aspects and an electrode active material.

The modified sulfide solid electrolyte makes it easier to form a contact interface between the electrode active material and the sulfide solid electrolyte, improving the paths for ionic and electronic conduction.

A lithium ion battery according to a twentieth aspect of this embodiment is
A lithium ion battery comprising at least one of the modified sulfide solid electrolyte of any one of the eleventh to eighteenth aspects and the electrode mixture of the nineteenth aspect.

Because the modified sulfide solid electrolyte and the electrode mixture have excellent properties as described above, lithium ion batteries using them have excellent battery properties.

The manufacturing method of the modified sulfide solid electrolyte, the modified sulfide solid electrolyte, the electrode mixture, and the lithium ion battery of this embodiment will be described in more detail below in accordance with the above-mentioned embodiment.

[Method for producing modified sulfide solid electrolyte]
The method for producing a modified sulfide solid electrolyte of the present embodiment includes heating a sulfide solid electrolyte having an argyrodite-type crystal structure and an oxide at 300° C. or more and 600° C. or less.
Hereinafter, a method for producing a modified sulfide solid electrolyte will be described, and then the sulfide solid electrolyte having an argyrodite-type crystal structure, the oxide, and the modified sulfide solid electrolyte will be described in detail.

＜Heating＞
The method for producing the modified sulfide solid electrolyte of the present embodiment is required to include heating a sulfide solid electrolyte having an argyrodite-type crystal structure described below and an oxide described below at 300° C. or more and 600° C. or less.
If the heating temperature is less than 300° C., the oxide does not adhere or bond to the surface of the primary particles of the sulfide solid electrolyte, as described below, and the effect of containing the oxide is not exhibited.If the heating temperature is higher than 600° C., the oxide is taken up into the sulfide solid electrolyte, or the argyrodite-type crystal structure is decomposed due to an interaction with the oxide, resulting in a significant decrease in ionic conductivity.
The heating temperature is preferably 350°C or higher and 580°C or lower, more preferably 400°C or higher and 560°C or lower, even more preferably 450°C or higher and 540°C or lower, and even more preferably 480°C or higher and 520°C or lower.

The heating is preferably carried out for one hour or more in order to obtain a modified sulfide solid electrolyte in which the generation of hydrogen sulfide is suppressed while maintaining the ionic conductivity of the sulfide solid electrolyte and suppressing an increase in the median diameter (D ₅₀ ), as described below.
The heating time is preferably 1 hour 30 minutes or more, more preferably 1 hour 40 minutes or more, and even more preferably 1 hour 50 minutes or more, in order to cause the oxide to adhere to or bond to the surfaces of the primary particles of the sulfide solid electrolyte.
There is no particular upper limit, but in order to maintain the argyrodite crystal structure of the sulfide solid electrolyte, the upper limit is preferably 10 hours or less, more preferably 5 hours or less, and even more preferably 3 hours or less.
That is, the heating time is preferably from 1 hour to 10 hours, more preferably from 1 hour 30 minutes to 5 hours, and even more preferably from 1 hour 40 minutes to 3 hours.

The heating is preferably performed in an inert gas atmosphere (e.g., nitrogen atmosphere, argon atmosphere) or a reduced pressure atmosphere (particularly in vacuum). For example, an inert gas atmosphere containing a certain concentration of hydrogen may be used. This is because deterioration (e.g., oxidation) of the crystalline sulfide solid electrolyte can be prevented.
The heating method is not particularly limited by the heater, and examples thereof include a method using a hot plate, a vacuum heating device, an argon gas atmosphere furnace, a baking furnace, etc. Also, for industrial purposes, a horizontal dryer having a heating means and a feeding mechanism, a horizontal vibration fluidized dryer, etc. may be used, and may be selected according to the amount of processing to be heated.

The heating is not particularly limited as long as the sulfide solid electrolyte and oxide are heated to 300°C or higher and 600°C or lower, but an oxide may be added to the heated sulfide solid electrolyte and further heated, or a sulfide solid electrolyte may be added to the heated oxide and further heated, or a mixture of the sulfide solid electrolyte and oxide may be heated. To obtain a mixture of the sulfide solid electrolyte and oxide, the sulfide solid electrolyte and oxide may be mixed as described below and then heated, or heating and mixing as described below may be performed simultaneously.

The heating is preferably performed by simultaneously heating the sulfide solid electrolyte and the oxide with a single heater. This is because a modified sulfide solid electrolyte containing the sulfide solid electrolyte and the oxide can be produced.

(Mixing)
The method for producing the modified sulfide solid electrolyte of the present embodiment preferably further includes mixing.
The mixing may be performed before the heating, or may be performed simultaneously with the heating, or a combination of these. Mixing before and/or simultaneously with the heating is preferable because the sulfide solid electrolyte is heated in a state in which the oxide is uniformly present on the surface thereof, and therefore a modified sulfide solid electrolyte in which the oxide is attached or bonded to the surfaces of the primary particles of the sulfide solid electrolyte is produced.
It is preferable to use a pulverizer to mix the sulfide solid electrolyte, as described below, since this allows the oxide to be present on the surface of the sulfide solid electrolyte while adjusting the median diameter (D ₅₀ ) of the sulfide solid electrolyte.

(Crushing)
The method for producing the modified sulfide solid electrolyte of this embodiment may further include pulverizing the sulfide solid electrolyte and/or the modified sulfide solid electrolyte. However, since the method for producing the modified sulfide solid electrolyte of this embodiment can suppress an increase in the median diameter (D ₅₀ ) of the sulfide solid electrolyte, it is preferable to heat the sulfide solid electrolyte so that the median diameter (D ₅₀ ) is a required size, and not pulverize the modified sulfide solid electrolyte after heating. This is because pulverization after heating produces a surface of the modified sulfide solid electrolyte that is not adhered with oxides. On the other hand, when the median diameter (D ₅₀ ) of the modified sulfide solid electrolyte increases due to heating, it is also preferable to pulverize the modified sulfide solid electrolyte for the purpose of crushing the secondary particles, rather than pulverizing the primary particles.

The pulverizer used for pulverizing the sulfide solid electrolyte is not particularly limited as long as it can pulverize particles, and for example, a media-type pulverizer using a pulverizing medium can be used. As the media-type pulverizer, a dry type pulverizer or a wet type pulverizer is preferable.
As the dry grinding machine, a dry media type grinding machine such as a dry bead mill, a dry ball mill, or a dry vibration mill, or a dry non-media type grinding machine such as a jet mill can be used.
As the wet grinding machine, a wet bead mill, a wet ball mill, a wet vibration mill, or the like can be used.

In addition, as a grinder used to grind the sulfide solid electrolyte and/or modified sulfide solid electrolyte, a machine capable of grinding an object using ultrasonic waves, such as a machine called an ultrasonic grinder, ultrasonic homogenizer, probe ultrasonic grinder, etc., can also be used.

The median diameter (D ₅₀ ) of the sulfide solid electrolyte and/or modified sulfide solid electrolyte obtained by pulverization is appropriately determined as desired, but is usually 0.01 μm or more and 50 μm or less, preferably 0.03 μm or more and 5 μm or less, and more preferably 0.05 μm or more and 3 μm or less.

[Modified sulfide solid electrolyte]
The modified sulfide solid electrolyte of the present embodiment is obtained by a production method including heating a sulfide solid electrolyte having an argyrodite-type crystal structure and an oxide at 300° C. or more and 600° C. or less, and includes a sulfide solid electrolyte having an argyrodite-type crystal structure containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and an oxide represented by the general formula M _m O _n (wherein M represents an atom selected from Mg, Al, Si, Ca, Ti, V, Fe, Zn, Ga, Sr, Y, Zr, Nb, Mo, Sn, Sb, Ba, Ta, W, and Bi, and m and n each independently represent an integer of 1 to 5), and satisfies the following (i) to (iii).
(i) At least one oxide in which M in the general formula M _m O _n is Al is included.
(ii) the ratio (M M /M _P ) of the total number of moles of M in all oxides contained in the modified sulfide solid electrolyte (M _M ) to the total number of moles of phosphorus atoms in the sulfide solid electrolyte ( _M _P ) is greater than 0.010.
(iii) Only one peak is observed within the range of 29.7±0.5 deg. in an X-ray diffraction spectrum (XRD pattern), or when two or more peaks are observed, _I2 / _I1 is less than 1.0, where _I1 is the intensity of the highest peak and _I2 is the intensity of the second highest peak.

The modified sulfide solid electrolyte of the present embodiment is a modified sulfide solid electrolyte that suppresses the generation of hydrogen sulfide while maintaining the ionic conductivity of the sulfide solid electrolyte. Because of such properties, it is useful as a material for an electrode mixture and a lithium ion battery, which will be described later. In addition, since the modified sulfide solid electrolyte contains an oxide, it is possible to suppress an increase in the median diameter (D ₅₀ ) of the modified sulfide solid electrolyte in particular. If the median diameter (D ₅₀ ) of the sulfide solid electrolyte can be reduced, it is preferable because it is easy to form a contact interface between the electrode active material and the sulfide solid electrolyte, and the paths for ionic conduction and electronic conduction are improved.

The modified sulfide solid electrolyte of the present embodiment is preferably a modified sulfide solid electrolyte in which the intensity ratio (peak intensity derived from oxide/peak intensity derived from argyrodite-type crystal structure) of the peak intensity derived from the oxide to the peak intensity of 29.7±0.5 deg. derived from the argyrodite-type crystal structure (peak intensity derived from argyrodite-type crystal structure) in an X-ray diffraction spectrum (XRD pattern) is less than 0.1.
As described above, when the intensity ratio is less than 0.1, the ionic conductivity of the sulfide solid electrolyte is maintained, an increase in the median diameter (D ₅₀ ) is suppressed, and generation of hydrogen sulfide can be further suppressed, which is preferable.

At first glance, the intensity ratio of less than 0.1 may be considered to mean that the oxide is not present in the modified sulfide solid electrolyte. However, considering that the oxide is added in a specified amount or more as in (i) and (ii) and should remain without interacting with the Argyrodite-type crystal structure (without contributing to the decomposition reaction of the Argyrodite-type crystal structure) as in (iii), the intensity ratio of less than 0.1 is considered to mean that the oxide itself is present in the modified sulfide solid electrolyte in a manner that is not observed in the XRD pattern. Specifically, it is presumed that the peak intensity of the XRD pattern originating from the oxide is small because the oxide is nanoparticles as described above, and the intensity ratio is small. The formation of the contact interface between the electrode active material and the modified sulfide solid electrolyte is inhibited by the oxide, but if the intensity ratio is less than 0.1, the formation of the contact interface is not inhibited and the path of electronic conduction is improved.
The modified sulfide solid electrolyte of the present embodiment is required to contain the sulfide solid electrolyte and the oxide, and preferably has the oxide attached or bonded to the surfaces of the primary particles of the sulfide solid electrolyte. The attachment and bonding are as described above.

The above (i) specifies that at least one oxide in which M is Al in the general _formula _MmOn is contained. This is preferable because it is possible to obtain a modified sulfide solid electrolyte in which the generation of hydrogen sulfide is suppressed while suppressing an increase in the median diameter ( _D50 ). Details will be described later.

As defined in (ii) above, the modified sulfide solid electrolyte of this embodiment requires that the ratio (M M /M P ) of the total number of moles of M in all oxides contained in the modified sulfide solid electrolyte (M _M ) to the total number _of moles of phosphorus atoms in the sulfide solid electrolyte (M _P ₎ is greater than 0.010.
The content ratio of an oxide, described below, and a sulfide solid electrolyte, described below, contained in the modified sulfide solid electrolyte can be roughly calculated from the above-mentioned M _M /M _P. M _M and M _P may be obtained from the oxide and sulfide solid electrolyte used in producing the modified sulfide solid electrolyte, or may be calculated by measuring the total content of M and the content of phosphorus atoms contained in the modified sulfide solid electrolyte by ICP atomic emission spectrometry or the like.
If the M _M /M _P is 0.010 or less, the effect of containing an oxide is not fully exhibited, and it is not possible to obtain a modified sulfide solid electrolyte in which the generation of hydrogen sulfide is suppressed while suppressing an increase in the median diameter (D ₅₀ ). The M _M /M _P is preferably 0.02 or more, more preferably 0.04 or more, and even more preferably 0.4 or more.
The upper limit is not particularly limited, and can be appropriately adjusted in order to maintain the ionic conductivity of the modified sulfide solid electrolyte.

In the modified sulfide solid electrolyte of this embodiment, if the median diameter ( _D50 ) is less than 150 μm, it is easy to form a contact interface between the electrode active material and the sulfide solid electrolyte, and the paths of ion conduction and electron conduction are improved, and by using this modified sulfide solid electrolyte, a lithium ion battery with excellent battery performance can be obtained, which is preferable. The median diameter ( _D50 ) is more preferably 100 μm or less, and even more preferably 80 μm or less. The lower limit is not particularly limited, but is preferably 10 μm or more.

<Sulfide solid electrolyte>
The sulfide solid electrolyte used in this embodiment is required to have an argyrodite-type crystal structure. Since the sulfide solid electrolyte has a high ionic conductivity due to the argyrodite-type crystal structure, the modified sulfide solid electrolyte also has a high ionic conductivity. The modified sulfide solid electrolyte of the present embodiment has properties equivalent to those of the sulfide solid electrolyte used in its production in terms of composition and properties.
Since the sulfide solid electrolyte used in this embodiment has an argyrodite-type crystal structure, the modified sulfide solid electrolyte of this embodiment, which is manufactured while retaining this argyrodite-type crystal structure, also has an argyrodite-type crystal structure. It will be held.
The sulfide solid electrolyte used in this embodiment is a crystalline solid electrolyte having an argyrodite-type crystal structure.
In the present disclosure, the term "crystalline solid electrolyte" refers to a solid electrolyte in which a peak derived from the solid electrolyte is observed in an X-ray diffraction pattern in an X-ray diffraction measurement, and the peak derived from the raw material of the solid electrolyte is In other words, a crystalline solid electrolyte includes a crystal structure derived from a solid electrolyte, and even if a part of the crystal structure is derived from the solid electrolyte, the whole of the crystal structure is derived from the solid electrolyte. The crystalline solid electrolyte may have a crystal structure derived from the amorphous solid electrolyte, if the crystalline solid electrolyte has the X-ray diffraction pattern as described above. It is a good thing.
The contents of lithium atoms, phosphorus atoms, and sulfur atoms in the sulfide solid electrolyte can be determined, for example, by measurement using an inductively coupled plasma (ICP) emission spectrometer.

(crystalline solid electrolyte)
The sulfide solid electrolyte used in this embodiment, and the modified sulfide solid electrolyte containing the sulfide solid electrolyte, have an argyrodite-type crystal structure.
The formula of the argyrodite crystal structure is Li _7-x-2y PS _6-x-y Cl _x (0.8≦x≦1.7, 0<y≦−0.25x+0.5). The argyrodite-type crystal structure represented by this composition formula is preferably a cubic crystal, and in X-ray diffraction measurement using CuKα radiation, the crystal structure has mainly 2θ=15.5°, 18.0°, 25.0°, It has peaks appearing at positions of 29.7°, 31.4°, 45.3°, 47.0°, and 52.0°.

Another example of the composition formula of the argyrodite-type crystal structure is Li7 _- xPS6 _-xHax ₍ Ha is Cl and/or Br, and x is preferably 0.2 to 1.8). The argyrodite-type crystal structure represented by this composition formula is preferably a cubic crystal, and has peaks that appear mainly at 2θ=15.5°, 18.0°, 25.0°, 29.7°, 31.4°, 45.3°, 47.0°, and 52.0° in X-ray diffraction measurement using CuKα radiation.
The positions of these peaks may vary within a range of ±0.5°.

Here, the sulfide solid electrolyte used in this embodiment, and the modified sulfide solid electrolyte containing this sulfide solid electrolyte, preferably contain lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms, and when atoms other than chlorine atoms are used as halogen atoms, it may not be expressed by the composition formula of "Li _7-x-2y PS _6-x-y Cl _x (0.8≦x≦1.7, 0<y≦-0.25x+0.5)". However, when it has the same diffraction peak as the diffraction peak described as the diffraction peak of the above "Argyrodite-type crystal structure", the sulfide solid electrolyte used in this embodiment, and the modified sulfide solid electrolyte containing this sulfide solid electrolyte, preferably have an Argyrodite-type crystal structure formed by lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms.

The sulfide solid electrolyte used in this embodiment and the modified sulfide solid electrolyte containing the sulfide solid electrolyte preferably contain lithium atoms, sulfur atoms, phosphorus atoms and halogen atoms. Representative examples include Li ₂ S-P 2 S ₅ , Li 2 S-P ₂ S 5 -LiI, Li ₂ S-P ₂ S ₅ -LiCl, Li ₂ S-P ₂ S ₅ -LiBr, Li ₂ S-P ₂ S ₅ -LiI, Li ₂ S-P ₂ S ₅ -LiCl-LiBr, Li ₂ S- _{P 2} _S ₅ _-LiI -LiBr, Li ₂ S- _{P 2} _S ₅ Preferred examples of the sulfide solid electrolyte include a sulfide solid electrolyte composed of lithium sulfide, phosphorus sulfide, and a lithium halide, such as _Li2S - _P2S5 -LiI, Li2S- _P2S5 -LiCl, _Li2S - _P2S5 _- LiBr, and Li2S- _P2S5 -LiI-LiBr. From the viewpoint of obtaining higher ionic conductivity, a sulfide solid electrolyte composed of lithium sulfide, phosphorus sulfide, and a lithium halide, such as _Li2S -P2S5-LiI, _Li2S - _P2S5 -LiCl, Li2S- _P2S5 -LiBr, and Li2S- _P2S5 -LiI-LiBr, is preferred.
It is preferable that the halogen atom contains at least one type selected from a chlorine atom and a bromine atom in order to stabilize the argyrodite type crystal structure.
The halogen atom preferably contains a chlorine atom, more preferably contains a bromine atom, and more preferably contains both a chlorine atom and a bromine atom.

In the sulfide solid electrolyte used in this embodiment, and in the modified sulfide solid electrolyte containing the sulfide solid electrolyte, the composition ratio (molar ratio) of lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms is preferably 1.0 to 1.8: 0.1 to 0.8: 1.0 to 2.0: 0.01 to 0.6, more preferably 1.1 to 1.7: 0.2 to 0.6: 1.2 to 1.8: 0.05 to 0.5, and even more preferably 1.2 to 1.6: 0.25 to 0.5: 1.3 to 1.7: 0.08 to 0.4.
In addition, when bromine and chlorine are used in combination as halogen atoms, the composition ratio (molar ratio) of lithium atoms, phosphorus atoms, sulfur atoms, bromine, and chlorine is preferably 1.0 to 1.8: 0.1 to 0.8: 1.0 to 2.0: 0.01 to 0.3: 0.01 to 0.3, more preferably 1.1 to 1.7: 0.2 to 0.6: 1.2 to 1.8: 0.02 to 0.25: 0.02 to 0.25, even more preferably 1.2 to 1.6: 0.25 to 0.5: 1.3 to 1.7: 0.03 to 0.2: 0.03 to 0.2, and still more preferably 1.35 to 1.45: 0.3 to 0.45: 1.4 to 1.7: 0.04 to 0.18: 0.04 to 0.18.

The above (iii) specifies that when only one peak is observed within the range of 29.7±0.5 deg. in an X-ray diffraction spectrum (XRD pattern), or when two or more peaks are observed, _I2 / _I1 is less than 1.0, where _I1 is the intensity of the highest peak and _I2 is the intensity of the second highest peak. The peak at 29.7±0.5 deg. characterizes the presence of an argyrodite-type crystal structure, and when only one peak is observed within this range, the observed peak is a peak derived from the argyrodite-type crystal structure, and when two or more peaks are observed, the highest peak is a peak derived from the argyrodite-type crystal structure (a peak with an intensity of _I1 ). The presence of peaks other than those derived from the Argyrodite-type crystal structure within the range of 29.7±0.5 deg. is considered to mean that a crystal structure similar to the Argyrodite-type crystal structure is contained in the modified sulfide solid electrolyte, and it is possible that an oxide has been incorporated into the Argyrodite-type crystal structure to change the crystal type, or that the crystalline substance has changed to something different. For this reason, it is preferable that no peaks other than those derived from the Argyrodite-type crystal structure are observed within the range of 29.7±0.5 deg., or even if they are observed, that the _I2 / _I1 is less than 1.0, since this makes it possible to obtain a modified sulfide solid electrolyte in which hydrogen sulfide generation is suppressed while maintaining the ionic conductivity of the sulfide solid electrolyte.

(Method for producing sulfide solid electrolyte)
The sulfide solid electrolyte used in the present embodiment is not particularly limited in its manufacturing method as long as it is a sulfide solid electrolyte having an argyrodite-type crystal structure containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms.
For example, the raw material components described below may be mixed, if necessary, with a solvent, and then, if necessary, dried, heated and/or pulverized to produce the toner.

(Raw material contents)
As the raw material contained in the raw material content, for example, a compound containing at least one of lithium atom, sulfur atom, and phosphorus atom can be used, and may contain halogen atom as necessary. More specifically, lithium sulfide; phosphorus sulfide such as diphosphorus trisulfide (P ₂ S ₃ ) and diphosphorus pentasulfide (P ₂ S ₅ ); and solid electrolytes such as amorphous Li ₃ PS ₄ or crystalline Li ₃ PS ₄ obtained from lithium sulfide and phosphorus sulfide and having a PS ₄ structure as a molecular structure can be mentioned. Examples of compounds containing halogen atoms include: lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide; phosphorus _halides such as various phosphorus fluorides ( _PF3 , _PF5 ), various phosphorus chlorides ( _PCl3 , _PCl5 , _P2Cl4 ), various phosphorus bromides ( _PBr3 , _PBr5 ), and various phosphorus iodides ( _PI3 , _P2I4 ); thiophosphoryl halides such as thiophosphoryl fluoride ( _PSF3 ), thiophosphoryl chloride ( _PSCl3 ), _{thiophosphoryl} bromide ( _PSBr3 ), thiophosphoryl iodide ( _PSI3 ), thiophosphoryl dichloride fluoride ( _PSCl2F ), and thiophosphoryl dibromide fluoride ( _PSBr2F ); and raw materials consisting of at least two atoms selected from the above four types of atoms, such as fluorine ( _F2 ), chlorine ( _Cl2 ), bromine ( _Br2F ), and the like. and iodine (I ₂ ). Preferred are chlorine (Cl ₂ ), bromine (Br ₂ ), and iodine (I ₂ ), and more preferred are bromine (Br ₂ ) and iodine (I ₂ ).

The raw material contents are preferably lithium sulfide and phosphorus sulfide, and the raw material containing halogen atoms more preferably contains at least one selected from lithium halide, phosphorus halide, and halogen molecules.
The use of at least one selected from lithium sulfide, phosphorus sulfide, lithium halide, phosphorus halide, and halogen molecules is preferred because it allows for the production of a sulfide solid electrolyte having high ionic conductivity. The use of lithium halide together with a complexing agent described below for the introduction of halogen atoms into the sulfide solid electrolyte is preferred because it allows for the production of a sulfide solid electrolyte having high ionic conductivity without separation of halogen atoms during removal of the solvent, etc., described below.
The halogen atom is preferably at least one selected from a chlorine atom and a bromine atom, more preferably contains a chlorine atom, more preferably contains a bromine atom, and more preferably contains both a chlorine atom and a bromine atom.

From the viewpoint of more easily obtaining a sulfide solid electrolyte having high ionic conductivity, among the above, phosphorus sulfides such as lithium sulfide, diphosphorus trisulfide (P ₂ S ₃ ), diphosphorus pentasulfide (P ₂ S ₅ ) are preferred as the raw material, and further, when a raw material containing a halogen atom is used, a halogen element (halogen molecule) such as fluorine (F ₂ ), chlorine (Cl ₂ ), bromine (Br ₂ ), iodine (I ₂ ), or a lithium halide such as lithium fluoride, lithium chloride, lithium bromide, or lithium iodide is preferred. Preferred combinations of raw materials include, for example, a combination of lithium sulfide, diphosphorus pentasulfide, and a lithium halide, and a combination of lithium sulfide, diphosphorus pentasulfide, and a halogen element, and lithium bromide and lithium chloride are preferred as the lithium halide, and bromine and chlorine are preferred as the halogen element.

The lithium sulfide used in this embodiment is preferably in the form of particles.
The median diameter (D ₅₀ ) of the lithium sulfide particles is preferably 10 μm or more and 2000 μm or less, more preferably 30 μm or more and 1500 μm or less, and even more preferably 50 μm or more and 1000 μm or less. In the present disclosure, the median diameter (D ₅₀ ) is the particle diameter at which the particle diameter reaches 50% of the whole when the particle diameter distribution cumulative curve is drawn by sequentially accumulating from the smallest particle diameter, and the volume distribution is, for example, the median diameter that can be measured using a laser diffraction/scattering type particle diameter distribution measuring device. In addition, among the examples of the raw materials, it is preferable that the solid raw materials have a median diameter of the same extent as the lithium sulfide particles. That is, it is preferable that the solid raw materials are within the same range as the median diameter of the lithium sulfide particles.

(Mixing)
The mixing in the production of the sulfide solid electrolyte may involve applying mechanical stress to the raw material contents to react while mixing, or may involve pulverization while mixing. Here, "applying mechanical stress" means mechanically applying shear force, impact force, etc. Examples of means for applying mechanical stress include pulverizers such as planetary ball mills, vibration mills, rolling mills, and bead mills, and kneaders such as single-shaft kneaders and multi-shaft kneaders.
The mixing may be carried out in the presence of a solvent (wet mixing) or without the use of a solvent (dry mixing).
In the case of dry mixing, the conditions for pulverizing and mixing are, for example, when a planetary ball mill is used as the pulverizer, a rotation speed of several tens to several hundreds of revolutions per minute and processing time of 0.5 to 100 hours.
When balls serving as grinding media are used, for example, zirconia balls, their diameter is preferably 0.2 to 20 mm.

In this embodiment, wet mixing is preferred since it may be possible to suppress the production of β-Li ₃ PS ₄ .
As the solvent, an organic solvent can be used, and preferably a non-polar solvent, a polar solvent, or a mixture thereof can be used. A non-polar solvent or a solvent mainly composed of a non-polar solvent, for example, 95% by mass or more of the total organic solvent is preferably a non-polar solvent.
The non-polar solvent is preferably a hydrocarbon solvent, and the hydrocarbon solvent may be a saturated hydrocarbon, an unsaturated hydrocarbon, or an aromatic hydrocarbon.
Examples of saturated hydrocarbons include hexane, pentane, 2-ethylhexane, heptane, decane, tridecane, and cyclohexane.

Examples of unsaturated hydrocarbons include hexene, heptene, and cyclohexene.
Examples of aromatic hydrocarbons include toluene, xylene, ethylbenzene, decalin, and 1,2,3,4-tetrahydronaphthalene.
Of these, toluene or xylene is preferred.

The hydrocarbon solvent is preferably dehydrated in advance. Specifically, the water content is preferably 100 ppm by mass or less, and more preferably 30 ppm by mass or less.
In this embodiment, the organic solvent preferably contains at least one of a nitrile compound and an ether compound.
Examples of the ether compound include tetrahydrofuran and diethyl ether.
The nitrile compound is preferably a nitrile compound represented by R(CN) _n , where R is an alkyl group having 1 to 10 carbon atoms or a group having an aromatic ring having 6 to 18 ring carbon atoms, and n is 1 or 2.

Examples of the nitrile include acetonitrile, propionitrile, 3-chloropropionitrile, benzonitrile, 4-fluorobenzonitrile, tertiary butyronitrile, isobutyronitrile, cyclohexylnitrile, capronitrile, isocapronitrile, malononitrile, and fumaronitrile. Preferred are propionitrile, isocapronitrile, and isobutyronitrile.
For example, nitrile compounds are preferred because they form an azeotrope with toluene and are therefore easily removed from the treated product together with toluene during drying.
The amount of the nitrile compound and the ether compound contained in the organic solvent is preferably from 0.01 to 5% by mass, more preferably from 0.1 to 3% by mass, and particularly preferably from 0.3 to 1% by mass.

In the wet mixing, it is preferable to use a bead mill. By mixing and grinding with a bead mill, the ground particle size of each raw material can be made smaller, which shortens the diffusion path of each element and makes each element more likely to be used to generate an _argyrodite -type crystal structure, which is thought to suppress the generation of a different phase such as a _Li3PS4 crystal structure.
The mixture of raw materials obtained by removing the solvent from the processed material after wet mixing using a bead mill is mainly composed of fine crystals. By mixing and grinding the raw materials, the raw materials are atomized, and a mixture of fine crystals of each raw material is obtained.

(Heating)
The method for producing the sulfide solid electrolyte used in the modified sulfide solid electrolyte of the present embodiment preferably further includes heating after the mixing step in the production of the sulfide solid electrolyte. It is preferable to include heating the complex to decomplex it, and heating the crystalline or amorphous sulfide solid electrolyte to obtain a crystalline solid electrolyte or a more crystallized crystalline sulfide solid electrolyte.
By including heating the complex, the complexing agent, the solvent, and the like in the complex are removed, and an amorphous sulfide solid electrolyte and/or a crystalline sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms is obtained.

The heating may be carried out in stages, such as calcination and firing.
The mixture of raw material contents is subjected to removal of the solvent to obtain a raw material mixture, which is then calcined to obtain a powdered calcined product. The heating temperature and time in the calcination can be appropriately adjusted in consideration of the composition of the calcined product, etc. For example, the heating temperature is preferably 150°C to 300°C, more preferably 160°C to 280°C, and particularly preferably 170°C to 250°C. The heating time is preferably 0.1 to 8 hours, more preferably 0.2 to 6 hours, and particularly preferably 0.25 to 4 hours.
The heating device used in the calcination is not particularly limited. For example, a shear type dryer such as an FM mixer or a Nauta mixer, a stationary furnace such as a hearth kiln, or a rotary furnace such as a rotary kiln may be used. Drying may be performed before calcination, or drying and calcination may be performed simultaneously. The atmosphere for calcination is not particularly limited, but an inert gas atmosphere such as nitrogen or argon is preferable.

When the mixture of raw material contents is calcined in a solvent, the above-mentioned non-polar solvent, polar solvent, or a mixture thereof can be used as the solvent used for calcination. The mixture is dispersed in the solvent to form a slurry, which is then heated. The solvent used for calcination may be the same as or different from the solvent used for mixing the raw materials. When the same solvent is used, it is preferable because it is not necessary to remove the solvent.
The heating temperature and time in the calcination can be appropriately adjusted taking into consideration the composition of the raw materials, etc. For example, the heating temperature is preferably 150°C to 300°C, more preferably 160°C to 280°C, further preferably 170°C to 270°C, and particularly preferably 180°C to 260°C. By setting the temperature within the above range, the _PS4 structure is formed, and halogen is easily incorporated into the argyrodite-type crystal structure. Since the raw material mixture of fine crystals is calcined in a solution, it is possible to form crystals containing the _PS4 structure at a relatively low temperature.

The heating time is preferably from 10 minutes to 6 hours, more preferably from 10 minutes to 3 hours, and particularly preferably from 30 minutes to 2 hours.
There are no particular limitations on the heating device used in the calcination, but when the heating temperature exceeds the boiling point of the solvent used, it is preferable to use an autoclave.
The solvent is removed from the slurry used in the calcination to recover the calcined product. The method for removing the solvent is not particularly limited, but the solvent can be distilled off under normal pressure or reduced pressure. In order to further increase productivity, filtration can also be used in combination.

The mixture or the calcined product obtained by mixing is fired to obtain a solid electrolyte. The heating temperature and time can be appropriately adjusted in consideration of the composition of the mixture and the calcined product. For example, the heating temperature is preferably 300°C to 470°C, more preferably more than 300°C to 460°C or less, more preferably 320°C to 450°C, further preferably 350°C to 440°C, and particularly preferably 380°C to 430°C.
The heating time is preferably from 1 to 360 minutes, more preferably from 5 to 120 minutes, and particularly preferably from 10 to 60 minutes.

The atmosphere during firing is not particularly limited, but is preferably an inert gas atmosphere such as nitrogen, argon, etc., rather than a hydrogen sulfide gas flow. For heating, a firing furnace such as a stationary hearth kiln or a rotary kiln can be used.
When the calcined product is fired, the above-mentioned non-polar solvent, polar solvent, or a mixture thereof can be used as the solvent used for heating. Heating is performed on the slurry in which the calcined product is dispersed in the solvent. The solvent used for heating may be the same as or different from the solvent used in the calcination. When the same solvent is used, it is preferable because it is not necessary to replace or remove the solvent before heating. In addition, as with the calcination, it is preferable to use an autoclave when the heating temperature exceeds the boiling point of the solvent used.
In addition, it is also preferable to heat the crystalline sulfide solid electrolyte so that the lattice constant of the argyrodite-type crystal structure can be adjusted to a preferred range, since this can increase the ionic conductivity.

The removal of the complexing agent from the complex is supported by the fact that it is clear from the results of X-ray diffraction patterns and gas chromatography analysis that the complexing agent forms a co-crystal with the raw material contents, etc., and that the sulfide solid electrolyte obtained by removing the complexing agent by heating the complex has the same X-ray diffraction pattern as the sulfide solid electrolyte obtained by the conventional method without using a complexing agent.

When the sulfide solid electrolyte is obtained by removing the complexing agent from the complex by heating the complex, the less complexing agent in the sulfide solid electrolyte, the better, but the complexing agent may be contained to an extent that does not impair the performance of the sulfide solid electrolyte. The content of the complexing agent in the sulfide solid electrolyte is usually 10 mass% or less, preferably 5 mass% or less, more preferably 3 mass% or less, and even more preferably 1 mass% or less. The lower limit is not particularly limited, since the lower the content, the better.

The heating temperature cannot be generally defined because it varies depending on the structure of the resulting crystalline sulfide solid electrolyte, but is usually preferably 250°C or less, more preferably 220°C or less, and even more preferably 200°C or less. There is no particular lower limit, but it is preferably 90°C or more, more preferably 100°C or more, and even more preferably 110°C or more.

The heating is preferably carried out under reduced pressure, preferably 0.1 Pa or more from the viewpoint of the apparatus, more preferably 1.0 Pa or more, and even more preferably 5.0 Pa or more, and from the viewpoint of obtaining a solid electrolyte with high ionic conductivity, preferably 100.0 Pa or less, more preferably 50.0 Pa or less, and even more preferably 20.0 Pa or less.

(Crushing)
The method for producing the modified sulfide solid electrolyte of the present embodiment may further include pulverizing the sulfide solid electrolyte. The pulverization is as described above. It is preferable to pulverize the sulfide solid electrolyte to reduce the median diameter (D ₅₀ ), since this also reduces the median diameter (D ₅₀ ) of the modified sulfide solid electrolyte of the present embodiment.

<Oxide>
The oxide used in the embodiment of the present application is required to contain a compound represented by the general formula M _m O _n (wherein M represents an atom selected from Mg, Al, Si, Ca, Ti, V, Fe, Zn, Ga, Sr, Y, Zr, Nb, Mo, Sn, Sb, Ba, Ta, W and Bi, and m and n each independently represent an integer of 1 to 5), and is used in the method for producing a modified sulfide solid electrolyte of the present embodiment.
In the formula, m and n are numbers appropriately determined depending on the valence of M.

In the general formula M _m O _n , M may be one type of atom or two or more types of atoms, but in consideration of availability, it is preferably one type of atom.
As the M, in order to suppress a decrease in the ionic conductivity of the sulfide solid electrolyte without affecting the argyrodite-type crystal structure, Mg, Al, Si, Ca, V, Fe, Zn, Ga, Sr, Y, Zr, Nb, Mo, Sn, Sb, Ba, Ta, W, and Bi are preferable. In order to obtain a modified sulfide solid electrolyte that is easy to obtain and suppresses the generation of hydrogen sulfide while maintaining the ionic conductivity of the sulfide solid electrolyte, Mg, Al, Si, Ti, Fe, Zn, Y, Zr, Nb, Mo, Sn, Ta, and W are more preferable, Al, Si, Ti, Zr, Nb, and Mo are even more preferable, and Al and Si are even more preferable.

It is preferable that the oxide contains an oxide (Al ₂ O ₃ ) in which M in the general formula M _m O _n is Al, and by heating together with the sulfide solid electrolyte at 300° C. to 600° C., a modified sulfide solid electrolyte in which Al ₂ O ₃ is adsorbed or bonded to the surfaces of the primary particles of the sulfide solid electrolyte can be obtained. Furthermore, when the oxide is Al ₂ O ₃ , it does not react with the sulfide solid electrolyte and the argyrodite crystal structure is maintained, so that the decrease in ion conductivity is suppressed even as a modified sulfide solid electrolyte, and it is preferable that the adsorption or bonding of Al ₂ O ₃ to the surfaces of the primary particles of the sulfide solid electrolyte can suppress an increase in the median diameter (D ₅₀ ) and a modified sulfide solid electrolyte in which hydrogen sulfide generation is suppressed can be obtained.

When the oxide contains an oxide ( _TiO4 ) in which M in the general _formula _MmOn is Ti, the argyrodite crystal structure changes, and the decrease in ionic conductivity becomes greater than when _Al2O3 is contained. However, this is preferable because the generation of _hydrogen sulfide is significantly suppressed while the increase in the median diameter ( _D50 ) is suppressed.
In particular, when _TiO4 is used as the oxide, it has been confirmed that a new peak appears at 35.4±0.5 deg. in the XRD chart of the modified sulfide solid electrolyte, although it is extremely weak compared to the peak intensity of 29.7±0.5 deg. due to the structure. This is preferable because it is found that a new crystal phase is generated by using _TiO4 , and it is possible to obtain a modified sulfide solid electrolyte in which the generation of hydrogen sulfide is suppressed while maintaining the ionic conductivity of the sulfide solid electrolyte. However, when focusing on ionic conductivity, it is preferable not to include an oxide in which M in the general _formula _MmOn is Ti.

The oxide may be only one type, or two or more types may be combined. When two or more types are combined, it is preferable to include an oxide (SiO ₂ ) in which M in the general formula M _m O _n is Si. By using SiO ₂ , it is preferable to be able to suppress the generation of hydrogen sulfide even if the amount of other oxides used is reduced. SiO ₂ can suppress the decrease in ion conductivity and suppress the generation of hydrogen sulfide. For example, when Al ₂ O ₃ and SiO ₂ are used in combination, the amount of Al ₂ O ₃ used can be reduced, so it is preferable to suppress the decrease in ion conductivity and suppress the generation of hydrogen sulfide.

The oxide may contain an oxide other than the general _formula _MmOn , but in order to suppress the generation of hydrogen sulfide while maintaining the ionic conductivity of the sulfide solid electrolyte and suppressing an increase in the median diameter ( _D50 ), the total content of the general _formula _MmOn in the oxide is preferably 80 mass% or more, more preferably 90 mass% or more, even more preferably 95 mass% or more, and even more preferably substantially only the general _formula _MmOn . In the present disclosure, "substantially" means that it is not intentionally contained.

The modified sulfide solid electrolyte is preferably in a state in which the oxide is attached or bonded to the surfaces of primary particles of the sulfide solid electrolyte, and the median diameter (D ₅₀ ) of the attached or bonded oxide is preferably less than 100.0 μm.
If the median diameter ( _D50 ) of the attached or bonded oxide is less than 100.0 μm, it becomes difficult for the oxide to come into contact with moisture in the atmosphere, and the generation of hydrogen sulfide is suppressed. This is also preferable because it suppresses the decrease in the ionic conductivity of the modified sulfide solid electrolyte and the increase in the median diameter ( _D50 ).

The median diameter (D ₅₀ ) of the attached or bonded oxide is more preferably 50.0 μm or less, and even more preferably 30.0 μm or less.
The median diameter (D ₅₀ ) of the attached or bonded oxide corresponds to the median diameter (D ₅₀ ) of the oxide used in the method for producing the modified sulfide solid electrolyte of this embodiment.

As described above, in the XRD pattern of the modified sulfide solid electrolyte, the intensity ratio (peak intensity from oxide/peak intensity from argyrodite crystal structure) between the peak intensity from the oxide and the peak intensity of 29.7±0.5 deg. from the argyrodite crystal structure (peak intensity from argyrodite crystal structure) is preferably less than 0.1, and most preferably is not substantially observable (less than the lower limit of the measuring device).

The positions of the peaks derived from oxides vary depending on the type of oxide, but as peaks that do not overlap with peaks derived from the argyrodite-type crystal structure and peaks derived from raw material contents, for example, they appear at 33.0±0.5 deg. and 37.0±0.5 deg. in alumina (Al ₂ O ₃ ), 38.0±0.5 deg. and 48.0±0.5 deg. in silica (SiO ₂ ), and 20.8±0.5 deg. and 26.5±0.5 deg. in titania (TiO 2 ) _.

[Electrode mixture]
The electrode mixture of the present embodiment is an electrode mixture containing the modified sulfide solid electrolyte of the present embodiment described above and an electrode active material.
(Electrode active material)
As the electrode active material, a positive electrode active material or a negative electrode active material is adopted depending on whether the electrode mixture is used for a positive electrode or a negative electrode.

The positive electrode active material can be any material that can promote a battery chemical reaction involving the movement of lithium ions resulting from atoms that are used to exhibit ionic conductivity in relation to the negative electrode active material, preferably lithium atoms, and is not particularly limited. Examples of such positive electrode active materials that can insert and remove lithium ions include oxide-based positive electrode active materials and sulfide-based positive electrode active materials.

Preferred examples of oxide-based positive electrode active materials include lithium-containing transition metal composite oxides such as LMO (lithium manganese oxide), LCO (lithium cobalt oxide), NMC (lithium nickel manganese cobalt oxide), NCA (lithium nickel cobalt aluminate), LNCO (lithium nickel cobalt oxide), and olivine-type compounds ( _LiMeNPO4 , Me = Fe, Co, Ni, Mn).
Examples of sulfide-based positive electrode active materials include titanium sulfide (TiS ₂ ), molybdenum sulfide (MoS ₂ ), iron sulfide (FeS, FeS ₂ ), copper sulfide (CuS), and nickel sulfide (Ni ₃ S ₂ ).
In addition to the above positive electrode active materials, niobium selenide (NbSe ₃ ) and the like can also be used.
The positive electrode active material may be used alone or in combination of two or more kinds.

The negative electrode active material can be used without any particular limitation as long as it can promote a battery chemical reaction accompanied by the movement of lithium ions caused by lithium atoms, such as an atom that is used as an atom that exhibits ion conductivity, preferably a metal that can form an alloy with lithium atoms, an oxide thereof, an alloy of the metal with lithium atoms, etc. As such a negative electrode active material capable of inserting and removing lithium ions, any material known in the battery field as a negative electrode active material can be used without any limitation.
Examples of such negative electrode active materials include metallic lithium, metallic indium, metallic aluminum, metallic silicon, metallic tin, and other metallic lithium or metals capable of forming alloys with metallic lithium, oxides of these metals, and alloys of these metals with metallic lithium.

The electrode active material used in this embodiment may have a coating layer on its surface.
Materials for forming the coating layer include ion conductors such as nitrides, oxides, and composites of atoms, preferably lithium atoms, that exhibit ion conductivity in the sulfide solid electrolyte. Specific examples include conductors having a lysicone-type crystal structure, such as Li _4-2x Zn _x GeO ₄ , which has a main structure of lithium nitride (Li ₃ N) and Li ₄ GeO ₄ , conductors having a thiolysicone-type crystal structure, such as Li _4-x Ge _1-x P _x S ₄ , which has a Li ₃ PO ₄ type skeleton structure, conductors having a perovskite-type crystal structure, such as La _2/3-x Li _3x TiO ₃ , and conductors having a NASICON-type crystal structure, such as LiTi ₂ (PO ₄ ) ₃ .
Other examples include lithium titanates such as Li _y Ti _3-y O ₄ (0<y<3) and Li ₄ Ti ₅ O ₁₂ (LTO), lithium metal oxides of metals belonging to Group 5 of the periodic table such as LiNbO ₃ and LiTaO ₃ , and oxide-based conductors such as Li ₂ O—B ₂ O ₃ —P ₂ O ₅ , Li ₂ O—B ₂ O ₃ —ZnO, and Li ₂ O—Al ₂ O ₃ —SiO ₂ —P ₂ O ₅ —TiO ₂ .

An electrode active material having a coating layer can be obtained, for example, by applying a solution containing various atoms constituting the material forming the coating layer to the surface of an electrode active material, and then baking the electrode active material after application at a temperature of preferably 200° C. or higher and 400° C. or lower.
Here, the solution containing various atoms may be a solution containing alkoxides of various metals such as lithium ethoxide, titanium isopropoxide, niobium isopropoxide, tantalum isopropoxide, etc. In this case, the solvent may be an alcohol solvent such as ethanol or butanol, an aliphatic hydrocarbon solvent such as hexane, heptane, or octane, or an aromatic hydrocarbon solvent such as benzene, toluene, or xylene.
The above attachment may be performed by immersion, spray coating, or the like.

From the viewpoint of improving manufacturing efficiency and battery performance, the firing temperature is preferably 200°C or higher and 400°C or lower, and more preferably 250°C or higher and 390°C or lower, and the firing time is usually about 1 minute to 10 hours, and preferably 10 minutes to 4 hours.

The coverage of the coating layer is preferably 90% or more, more preferably 95% or more, and even more preferably 100% based on the surface area of the electrode active material, that is, the entire surface is preferably covered. The thickness of the coating layer is preferably 1 nm or more, more preferably 2 nm or more, and the upper limit is preferably 30 nm or less, more preferably 25 nm or less.
The thickness of the coating layer can be measured by cross-sectional observation using a transmission electron microscope (TEM), and the coverage rate can be calculated from the thickness of the coating layer, elemental analysis values, and BET specific surface area.

(Other ingredients)
The electrode mixture of this embodiment may contain other components such as a conductive material, a binder, etc. in addition to the modified sulfide solid electrolyte and the electrode active material. That is, the electrode mixture of this embodiment may contain other components such as a conductive material, a binder, etc. in addition to the modified sulfide solid electrolyte and the electrode active material. The other components such as a conductive material, a binder, etc. may be further added to and mixed with the modified sulfide solid electrolyte and the electrode active material when the modified sulfide solid electrolyte and the electrode active material are mixed together.
Examples of the conductive material, from the viewpoint of improving battery performance by improving electronic conductivity, include carbon-based materials such as artificial graphite, graphite carbon fiber, resin-calcined carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads, furfuryl alcohol resin-calcined carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon.

By using a binder, the strength of the positive and negative electrodes is improved.
The binder is not particularly limited as long as it can impart functions such as binding property and flexibility, and examples thereof include fluorine-based polymers such as polytetrafluoroethylene and polyvinylidene fluoride, thermoplastic elastomers such as butylene rubber and styrene-butadiene rubber, and various resins such as acrylic resins, acrylic polyol resins, polyvinyl acetal resins, polyvinyl butyral resins, and silicone resins.

The compounding ratio (mass ratio) of the electrode active material to the modified sulfide solid electrolyte in the electrode mixture is preferably 99.5:0.5 to 40:60, more preferably 99:1 to 50:50, and even more preferably 98:2 to 60:40, in order to improve battery performance and take into consideration manufacturing efficiency.

When a conductive material is contained, the content of the conductive material in the electrode mixture is not particularly limited, but in consideration of improving battery performance and production efficiency, the content is preferably 0.5 mass% or more, more preferably 1 mass% or more, and even more preferably 1.5 mass% or more, and the upper limit is preferably 10 mass% or less, preferably 8 mass% or less, and even more preferably 5 mass% or less.
Furthermore, when a binder is contained, the content of the binder in the electrode mixture is not particularly limited, but in consideration of improving battery performance and production efficiency, the content is preferably 1 mass % or more, more preferably 3 mass % or more, and even more preferably 5 mass % or more, and the upper limit is preferably 20 mass % or less, preferably 15 mass % or less, and even more preferably 10 mass % or less.

[Lithium-ion battery]
The lithium ion battery of this embodiment is required to contain at least one selected from the modified sulfide solid electrolyte of this embodiment and the electrode mixture.

The lithium ion battery of this embodiment is not particularly limited in its configuration as long as it contains either the modified sulfide solid electrolyte of this embodiment or an electrode composite material containing the same, and it may have the configuration of a commonly used lithium ion battery.

The lithium ion battery of this embodiment preferably includes, for example, a positive electrode layer, a negative electrode layer, an electrolyte layer, and a current collector. The positive electrode layer and the negative electrode layer preferably use the electrode mixture of this embodiment, and the electrolyte layer preferably uses the modified sulfide solid electrolyte of this embodiment.

The current collector may be any known material. For example, a layer of a material that reacts with the solid electrolyte, such as Au, Pt, Al, Ti, or Cu, coated with Au or the like can be used.

The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples in any way.

(1) Measurement Method (1-1) Measurement of Ion Conductivity In this example, the measurement of ion conductivity was carried out as follows.
A circular pellet with a diameter of 10 mm (cross-sectional area S: 0.785 cm ² ) and a height (L) of 0.1 to 0.3 cm was molded from the solid electrolyte to prepare a sample. Electrode terminals were attached to the top and bottom of the sample, and measurements were made at 25°C by an AC impedance method (frequency range: 1 MHz to 100 Hz, amplitude: 10 mV) to obtain a Cole-Cole plot. The real part Z' (Ω) at the point where -Z'' (Ω) is minimum near the right end of the arc observed in the high frequency region was taken as the bulk resistance R (Ω) of the electrolyte, and the ionic conductivity σ (S/cm) was calculated according to the following formula:
R = ρ(L/S)
σ=1/ρ

(1-2) Measurement of the amount of hydrogen sulfide generated The following exposure test was carried out and the amount of hydrogen sulfide generated was measured.
First, a test apparatus (exposure test apparatus 1) used in the exposure test will be described with reference to FIG.
The exposure test apparatus 1 mainly comprises a flask 10 for humidifying nitrogen, a static mixer 20 for mixing humidified nitrogen and non-humidified nitrogen, a dew point meter 30 (M170/DMT152 manufactured by VAISALA) for measuring the moisture content of the mixed nitrogen, a double reaction tube 40 in which a measurement sample is placed, a dew point meter 50 for measuring the moisture content of the nitrogen discharged from the double reaction tube 40, and a hydrogen sulfide meter 60 (Model 3000RS manufactured by AMI) for measuring the hydrogen sulfide concentration contained in the discharged nitrogen, and is configured to be connected by pipes (not shown). The temperature of the flask 10 is set to 10° C. by a cooling tank 11.
The components were connected to each other using Teflon tubes with a diameter of 6 mm. In this figure, the tubes are omitted, and instead the flow of nitrogen is indicated by arrows.

The evaluation procedure was as follows.
In a nitrogen glove box with a dew point of −80° C., about 1.5 g of the powder sample 41 obtained in the examples and comparative examples was weighed out, placed in a reaction tube 40 so as to be sandwiched between quartz wool 42, and sealed. The evaluation was carried out at room temperature (20° C.).
Nitrogen was supplied from a nitrogen source (not shown) at 0.02 MPa into the apparatus 1. The supplied nitrogen passed through a bifurcated branch pipe BP, and a portion of the nitrogen was supplied to the flask 10 and humidified. The remaining portion was supplied directly to the static mixer 20 as unhumidified nitrogen. The amount of nitrogen supplied to the flask 10 was adjusted by a needle valve V.
The flow rates of non-humidified nitrogen and humidified nitrogen were adjusted with a flow meter FM equipped with a needle valve to control the dew point. Specifically, non-humidified nitrogen was supplied to the static mixer 20 at a flow rate of 800 mL/min, and humidified nitrogen was supplied to the static mixer 20 at a flow rate of 10 to 30 mL/min, and mixed. The dew point of the mixed gas (a mixture of non-humidified nitrogen and humidified nitrogen) was confirmed with a dew point meter 30.

After adjusting the dew point to -30°C, the three-way cock 43 was rotated to circulate the mixed gas inside the reaction tube 40 for 2 hours. The amount of hydrogen sulfide contained in the mixed gas that passed through the sample 41 was measured with a hydrogen sulfide meter 60. The amount of hydrogen sulfide was recorded at 15-second intervals. For reference, the dew point of the mixed gas after exposure was also measured with a dew point meter 50. The amounts of hydrogen sulfide ( _H2S ) generated (cumulative) for 60 minutes and 120 minutes from the start of measurement are shown in Table 1.
In order to remove hydrogen sulfide from the nitrogen after measurement, the nitrogen was passed through an alkali trap 70.

(1-3) Powder X-ray Diffraction (XRD) Measurement Powder X-ray diffraction (XRD) measurement was carried out as follows.
The powder of the modified sulfide solid electrolyte obtained in the examples and comparative examples was filled into a groove having a diameter of 20 mm and a depth of 0.2 mm, and the groove was leveled with glass to prepare a sample. The sample was sealed with a Kapton film for XRD and measured under the following conditions without exposing it to air.
Measurement device: D2 PHASER, manufactured by Bruker Corporation Tube voltage: 30 kV
Tube current: 10mA
X-ray wavelength: Cu-Kα ray (1.5418 Å)
Optical system: focusing method Slit configuration: Soller slit 4°, divergence slit 1 mm, Kβ filter (Ni plate) used Detector: semiconductor detector Measurement range: 2θ = 10-60 deg
Step width, scan speed: 0.05 deg, 0.05 deg/sec. From the obtained XRD pattern, the peak intensity derived from the oxide and the peak intensity at 29.7±0.5 deg. derived from the argyrodite crystal structure (peak intensity derived from the argyrodite crystal structure) were measured. From these peak intensities, the intensity ratio (peak intensity derived from the oxide/peak intensity derived from the argyrodite crystal structure) between the peak intensity derived from the oxide and the peak intensity at 29.7±0.5 deg. derived from the argyrodite crystal structure (peak intensity derived from the argyrodite crystal structure) was calculated.

(1-4) Median diameter ( _D50 )
The volume-based median diameter was measured using a laser diffraction/scattering particle size distribution measuring device ("Partica LA-950V2 model LA-950W2", manufactured by Horiba, Ltd.). A mixture of dehydrated toluene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade) and tertiary butyl alcohol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade) in a weight ratio of 93.8:6.2 was used as the dispersion medium. 50 ml of the dispersion medium was injected into the flow cell of the device and circulated, after which the measurement target was introduced and subjected to ultrasonic treatment, and the particle size distribution was measured. The amount of the measurement target introduced was adjusted so that the red light transmittance (R) corresponding to the particle concentration was within 80 to 90% and the blue light transmittance (B) was within 70 to 90% on the measurement screen specified by the device. In addition, 2.16 was used as the refractive index value of the measurement target, and 1.49 was used as the refractive index value of the dispersion medium, respectively, for the calculation conditions. In setting the distribution form, the number of repetitions was fixed at 15, particle size calculation was performed, and the median diameter (D ₅₀ ) of the sulfide solid electrolyte and oxide was obtained.

(2) Production of sulfide solid electrolyte (2-1) Preparation of lithium sulfide (Li ₂ S) Toluene (manufactured by Sumitomo Corporation) was dehydrated as a non-aqueous medium, and 303.8 kg of the product was added to a 500 L stainless steel reaction kettle under a nitrogen stream, followed by 33.8 kg of anhydrous lithium hydroxide (manufactured by Honjo Chemical Co., Ltd.) and maintained at 95 ° C. while stirring with a twin star stirring blade at 131 rpm. The temperature was raised to 104 ° C. while blowing hydrogen sulfide (manufactured by Sumitomo Seika Chemicals Co., Ltd.) into the slurry at a supply rate of 100 L / min. Azeotropic gas of water and toluene was continuously discharged from the reaction kettle. This azeotropic gas was dehydrated by condensing it with a condenser outside the system. During this time, toluene in the same amount as the toluene distilled was continuously supplied to maintain the reaction liquid level constant. The amount of water in the condensate gradually decreased, and 24 hours after the introduction of hydrogen sulfide, distillation of water was no longer observed. During the reaction, the solid was dispersed and stirred in the toluene, and no water was separated from the toluene. After this, hydrogen sulfide was replaced with nitrogen and circulated at 100 L/min for 1 hour. The obtained solid was filtered and dried to obtain Li ₂ S, a white powder.

(2-2) Production of sulfide solid electrolyte having an argyrodite-type crystal structure (A) Grinding step The Li ₂ S obtained in (2-1) was ground in a pin mill (100UPZ, manufactured by Hosokawa Micron Corporation) having a constant-volume feeder under a nitrogen atmosphere. The feeding rate was 80 g/min, and the rotation speed of the disk was 18,000 rpm. Similarly, P ₂ S ₅ (manufactured by Italmatch), LiBr (manufactured by Honjo Chemical Co., Ltd.), and LiCl (manufactured by Honjo Chemical Co., Ltd.) were each ground in a pin mill. The feeding rate of P ₂ S ₅ was 140 g/min, the feeding rate of LiBr was 230 g/min, and the feeding rate of LiCl was 250 g/min. The rotation speed of the disk was 18,000 rpm in each case.

(B) Preparation of raw material mixture In a glove box under nitrogen atmosphere, the compounds pulverized in (A) were weighed out so that the molar ratio was Li ₂ S:P ₂ S ₅ :LiBr:LiCl=47.5:12.5:15.0:25.0, and the total was 110 g, and the compounds were put into a glass container and roughly mixed by shaking the container. After the rough mixing, the total amount was dispersed in a mixed solvent of 1140 mL of dehydrated toluene (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) and 7 mL of dehydrated isobutyronitrile (manufactured by Kishida Chemical Co., Ltd.) under a nitrogen atmosphere to obtain a slurry of about 10% by weight. The slurry was mixed and pulverized using a bead mill (LMZ015, manufactured by Ashizawa Finetech Co., Ltd.) while maintaining the nitrogen atmosphere. Specifically, 456 g of zirconia beads having a diameter of 0.5 mm were used as the grinding medium, and the bead mill was operated under conditions of a peripheral speed of 12 m/s and a flow rate of 500 mL/min, and the slurry was charged into the mill and circulated for 1 hour. The treated slurry was placed in a nitrogen-substituted Schlenk flask and then dried under reduced pressure to prepare a raw material mixture.

(C) Calcination Step 30 g of the raw material mixture obtained in (B) was dispersed in 300 mL of ethylbenzene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to obtain a slurry. This slurry was placed in an autoclave (capacity 1000 mL, made of SUS316) equipped with a stirrer and a heating oil bath, and heat-treated at 200° C. for 2 hours while stirring at a rotation speed of 200 rpm. After the treatment, the mixture was dried under reduced pressure to remove the solvent, and a calcined product was obtained.

(D) Firing step The calcined product obtained in (C) was heated in an electric furnace (F-1404-A, manufactured by Tokyo Glass Machinery Co., Ltd.) in a glove box under a nitrogen atmosphere. Specifically, an Al ₂ O ₃ sagger (999-60S, manufactured by Tokyo Glass Machinery Co., Ltd.) was placed in the electric furnace, and the temperature was raised from room temperature (20°C) to 380°C in 1 hour and maintained at 380°C for 1 hour or more. Thereafter, the door of the electric furnace was opened, and the calcined product was quickly poured into the sagger, after which the door was immediately closed and heated for 1 hour. Thereafter, the sagger was removed from the electric furnace and slowly cooled to obtain a sulfide solid electrolyte.

(E) Microparticulation step The sulfide solid electrolyte obtained in (D) was dispersed in a mixed solvent of dehydrated toluene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and dehydrated isobutyronitrile (manufactured by Kishida Chemical Co., Ltd.) under a nitrogen atmosphere to obtain a slurry of about 8% by weight. The slurry was mixed and pulverized using a bead mill (LMZ015, manufactured by Ashizawa Finetech Co., Ltd.) while maintaining the nitrogen atmosphere. The treated slurry was placed in a nitrogen-substituted Schlenk flask, and then dried under reduced pressure to obtain a microparticulated sulfide solid electrolyte (sulfide solid electrolyte (C1)).
Example 1

(F) Oxide material addition step Under a nitrogen atmosphere, 0.150 g of _Al2O3 raw material (manufactured by _Nippon Aerosil Co., Ltd.) was weighed out for 1.350 g of the sulfide solid electrolyte (C1) obtained in (E) above, and was placed in a zirconia container (manufactured by Fritsch). Next, 80 zirconia balls with a diameter of 5 mm were poured into the zirconia container, which was then sealed. After that, a rolling mill (small ball mill AV type, manufactured by Asahi Rika Seisakusho Co., Ltd.) was used to perform dry mixing at a rotation speed of 600 rpm for 1 hour, to obtain a sulfide solid electrolyte (sulfide solid electrolyte (C2)).

(G) Secondary Firing Step The sulfide solid electrolyte (C2) obtained in (F) was heated in an electric furnace (manufactured by AS ONE Corporation) in a glove box. Specifically, an Al ₂ O ₃ crucible (manufactured by Nikkato Corporation) was placed in the electric furnace, and the temperature was raised from room temperature (20° C.) to 500° C. at a rate of 6° C./min and held at 500° C. for 2 hours or more. The crucible was then removed from the electric furnace and slowly cooled to produce a sulfide solid electrolyte having an argyrodite-type crystal structure (modified sulfide solid electrolyte (1)). The presence of the argyrodite-type crystal structure was confirmed by XRD measurement. The ionic conductivity, amount of hydrogen sulfide generated, XRD pattern, and median diameter (D ₅₀ ) were measured using the modified sulfide solid electrolyte (1). The results are shown in Table 2.

(Example 2) to (Example 5)
Modified sulfide solid electrolytes (2) to (5) were obtained in the same manner as in Example 1, except that the types and amounts of oxides used were those shown in Table 1. The ionic conductivity, amount of hydrogen sulfide generated, XRD pattern, and median diameter (D ₅₀ ) are shown in Table 2.
In Table 1, oxide 1 means the first oxide used, and the amount of oxide 1 added is recorded as added amount 1, and when a second oxide was used, it is recorded as oxide 2, and the amount of oxide 1 added is recorded as added amount 2.

(Comparative Example 1)
The sulfide solid electrolyte (C1) was used as the sulfide solid electrolyte of Comparative Example 1. Table 2 shows the ionic conductivity, the amount of hydrogen sulfide generated, the XRD pattern, and the median diameter (D ₅₀ ).

(Comparative Example 2)
The sulfide solid electrolyte (C2) was used as the sulfide solid electrolyte of Comparative Example 2. The sulfide solid electrolyte of Comparative Example 2 corresponds to the modified sulfide solid electrolyte of Example 1 before heating. The ionic conductivity, amount of hydrogen sulfide generated, XRD pattern, and median diameter (D ₅₀ ) are shown in Table 2.

(Comparative Example 3) to (Comparative Example 6)
Sulfide solid electrolytes (C3) to (C6) were obtained in the same manner as in Comparative Example 2, except that the types and amounts of oxides used were those shown in Table 1. The sulfide solid electrolytes of Comparative Examples 3 to 6 correspond to the modified sulfide solid electrolytes of Examples 2 to 5 before heating. The ionic conductivity, amount of hydrogen sulfide generated, XRD pattern, and median diameter (D ₅₀ ) are shown in Table 2.

(Comparative Example 7)
The sulfide solid electrolyte (C4) was heated at 650° C. for 2 hours under a nitrogen atmosphere. The sulfide solid electrolyte of Comparative Example 7 corresponds to the sulfide solid electrolytes described in

Patent Documents

5 and 6. The ionic conductivity, hydrogen sulfide generation amount, XRD pattern, and median diameter (D ₅₀ ) of the obtained modified sulfide solid electrolyte (modified sulfide solid electrolyte (C7)) were measured. The results are shown in Table 2.

(Comparative Example 8)
The sulfide solid electrolyte (C5) was heated at 650° C. for 2 hours under a nitrogen atmosphere. The sulfide solid electrolyte of Comparative Example 8 corresponds to the sulfide solid electrolyte described in

Patent Documents

5 and 6. The ionic conductivity, hydrogen sulfide generation amount, XRD pattern, and median diameter (D ₅₀ ) of the obtained modified sulfide solid electrolyte (modified sulfide solid electrolyte (C8)) were measured. The results are shown in Table 2.

In Table 2, M _M /M _P represents the ratio of the total number of moles of M in all oxides contained in the modified sulfide solid electrolyte (M _M ) to the total number of moles of phosphorus atoms in the sulfide solid electrolyte (M _P ), and the intensity ratio represents the intensity ratio (peak intensity derived from oxide/peak intensity derived from argyrodite-type crystal structure) between the peak intensity derived from the oxide in an X-ray diffraction spectrum (XRD pattern) and the peak intensity of 29.7±0.5 deg. derived from the argyrodite-type crystal structure (peak intensity derived from argyrodite-type crystal structure).

The median diameter (D ₅₀ ) of the oxides used in the examples and comparative examples is 13 μm for aluminum oxide (alumina, Al ₂ O ₃ ), 20 μm for silicon oxide (silica, SiO ₂ ), and 14 μm for titanium oxide (titania, TiO ₂ ).

In the table, "-" for Oxide 1 and Oxide 2 means that no oxide was used, and "-" for Addition Amount 1 and Addition Amount 2 means that no oxide was used, and therefore the addition amount is 0 mass%. "-" for heating temperature means that heating was not performed in the manufacturing method of claim 1.

In Table 2, "-" means that only one peak is observed at 29.7±0.5 deg. and there is no peak with the second highest peak intensity. _I1 means the peak intensity when only one peak is observed within the range of 29.7±0.5 deg., and means the intensity of the highest peak when two or more peaks are observed within the range of 29.7±0.5 deg. _I2 means the intensity of the second highest peak when two or more peaks are observed within the range of 29.7±0.5 deg.

The peak intensity derived from the oxide and the peak intensity at 29.7±0.5 deg. derived from the argyrodite crystal structure (peak intensity derived from the argyrodite crystal structure) are shown in Table 3.

In Table 3, "N/A" means that no peaks corresponding to oxide-derived peaks were observed.

The produced modified sulfide solid electrolyte (1), modified sulfide solid electrolyte (2), modified sulfide solid electrolyte (4) and modified sulfide solid electrolyte (5) were found to be modified sulfide solid electrolytes in which the generation of hydrogen sulfide was suppressed while maintaining the ionic conductivity of the sulfide solid electrolyte and suppressing an increase in the median diameter ( _D50 ).

In the XRD pattern of the modified sulfide solid electrolyte (3), a peak was observed at 35.4° derived from a new crystal phase, which was not observed in the XRD patterns of the modified sulfide solid electrolyte (1) and the like, and the intensity was 12,000 counts. Since a new peak appeared when _TiO4 was used as the oxide, it was confirmed that a new crystal phase was generated. Although a new crystal phase was generated, it was found that the reduction of hydrogen sulfide was significantly suppressed.

The results of Comparative Example 1 show that the modified sulfide solid electrolyte of the present embodiment can suppress the generation of hydrogen sulfide. Moreover, the results of Comparative Examples 2 to 6 show that the generation of hydrogen sulfide cannot be suppressed by simply mixing an oxide with a sulfide solid electrolyte, and that heating is necessary.
Furthermore, from the results of Comparative Examples 7 and 8, it was found that when the heating temperature was set to a high temperature such as 650° C. as in the methods for producing a sulfide solid electrolyte described in

Patent Documents

5 and 6, the ionic conductivity was significantly reduced and the median diameter (D ₅₀ ) was also increased.

3 is a graph showing the change over time in the cumulative generation amount and instantaneous generation amount of hydrogen sulfide. In FIG. 3, solid line 1 shows the cumulative generation amount (cumulative) from 0 minutes into the gas flow time of hydrogen sulfide (H ₂ S) for the modified sulfide solid electrolyte (5), solid line 2 shows the cumulative generation amount (cumulative) for each time from 0 minutes into the gas flow time of the modified sulfide solid electrolyte (C6), and solid line 3 shows the cumulative generation amount (cumulative) for each time from 0 minutes into the gas flow time of the modified sulfide solid electrolyte (C8). In FIG. 3, dashed line 4 shows the instantaneous generation amount of hydrogen sulfide (H 2 S) for the modified sulfide solid electrolyte (5), dashed line 5 shows the instantaneous generation amount of hydrogen sulfide (H 2 S) for each gas flow time for the modified sulfide solid electrolyte (C6), and dashed line 6 shows the instantaneous generation amount of hydrogen sulfide (H ₂ S) for each gas flow time for the modified sulfide solid electrolyte (C8).

The sulfide solid electrolytes of Example 5, Comparative Example 6, and Comparative Example 8 all use 2.7 mass% _Al2O3 as an oxide. However, Comparative Example 6 was not heated, Example 5 was heated at 500°C, and Comparative Example 8 was heated at 650°C. From Fig. 3, Comparative Example ₆ always has a high instantaneous generation amount and a large cumulative generation amount. In contrast, when comparing Example 5 and Comparative Example 8, it can be seen that although Comparative Example 8 has a lower initial instantaneous generation amount, the difference between the two disappears after about 60 minutes.

FIG. 4 shows XRD patterns of the sulfide solid electrolytes obtained in Example 5, Comparative Example 6, and Comparative Example 8.
From the XRD patterns of Example 5 and Comparative Example 6, it can be seen that the argyrodite-type crystal structure is maintained even when heated at 500°C. In contrast, in Comparative Example 8, it can be seen that new peaks appear before and after the peaks that showed strong peak intensities in the XRD patterns of Example 5 and Comparative Example 6. This is thought to be because, in the manufacturing method of Comparative Example 8, the sulfide solid electrolyte is heated at a high temperature together with the oxide, and the oxide is incorporated into the crystal structure of the sulfide solid electrolyte. In this way, it is thought that the sulfide solid electrolyte of Comparative Example 8 suppresses the generation of hydrogen sulfide by incorporating the oxide into the crystal structure and modifying it. However, when the sulfide solid electrolyte is modified in this way, it can be seen that the ionic conductivity of the sulfide solid electrolyte of Comparative Example 8 is greatly reduced, as shown in Table 2. In addition, the median diameter (D ₅₀ ) of the sulfide solid electrolyte of Comparative Example 8 is greatly increased by heating at a high temperature, so that it becomes necessary to crush it afterwards.

According to the present embodiment, it is possible to provide a method for producing a modified sulfide solid electrolyte that can obtain a modified sulfide solid electrolyte in which the generation of hydrogen sulfide is suppressed while suppressing an increase in the median diameter (D ₅₀ ) and maintaining the ionic conductivity of the sulfide solid electrolyte; it is also possible to provide the modified sulfide solid electrolyte; and it is also possible to provide an electrode mixture and a lithium ion battery that include the modified sulfide solid electrolyte.
The modified sulfide solid electrolyte obtained by the production method of this embodiment is suitable for use in lithium ion batteries, particularly lithium ion batteries used in information-related devices and communication devices such as personal computers, video cameras, and mobile phones.

Reference Signs List 1 Exposure test apparatus 10 Flask 11 Cooling tank 20 Static mixer 30 Dew point meter 40 Double reaction tube 41 Sample 42 Quartz wool 43 Three-way cock 50 Dew point meter 60 Hydrogen sulfide measuring instrument 70 Alkaline trap BP Bifurcated branch pipe V Needle valve FM Flow meter with needle valve

Claims

A method for producing a modified sulfide solid electrolyte, comprising heating a sulfide solid electrolyte having an argyrodite-type crystal structure and an oxide at 300°C or higher and 600°C or lower.
The method for producing a modified sulfide solid electrolyte according to claim 1, wherein the sulfide solid electrolyte contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms.
The method for producing a modified sulfide solid electrolyte according to claim 2, wherein the halogen atoms include at least one selected from chlorine atoms and bromine atoms.
The method for producing a modified sulfide solid electrolyte according to any one of claims 1 to 3, wherein the oxide comprises a compound represented by the general formula M m O n (wherein M represents an atom selected from Mg, Al, Si, Ca, Ti, V, Fe, Zn, Ga, Sr, Y, Zr, Nb, Mo, Sn, Sb, Ba, Ta, W and Bi, and m and n each independently represent an integer of 1 to 5).
The method for producing a modified sulfide solid electrolyte according to claim 4, comprising an oxide in which M in the general formula MmOn is Al.
6. The method for producing a modified sulfide solid electrolyte according to claim 5, wherein a ratio (M M /M P ) of the total number of moles of M in the oxide (M M ) to the total number of moles of phosphorus atoms in the sulfide solid electrolyte (M P ) is greater than 0.010.
The method for producing a modified sulfide solid electrolyte according to any one of claims 1 to 6, wherein the heating is carried out for one hour or more.
A method for producing the modified sulfide solid electrolyte according to any one of claims 1 to 7, further comprising mixing.
The heating step comprises:
The method for producing a modified sulfide solid electrolyte according to any one of claims 1 to 8, wherein the sulfide solid electrolyte and the oxide are heated simultaneously in one heater.
The method for producing a modified sulfide solid electrolyte according to any one of claims 1 to 9, wherein the median diameter (D 50 ) of the oxide attached to or bonded to the surface of a primary particle of the modified sulfide solid electrolyte is less than 100.0 μm.
a sulfide solid electrolyte having an argyrodite-type crystal structure containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms;
and an oxide represented by the general formula M m O n (wherein M represents an atom selected from Mg, Al, Si, Ca, Ti, V, Fe, Zn, Ga, Sr, Y, Zr, Nb, Mo, Sn, Sb, Ba, Ta, W and Bi, and m and n each independently represent an integer of 1 to 5),
A modified sulfide solid electrolyte that satisfies the following (i) to (iii):
(i) At least one oxide in which M in the general formula M m O n is Al is contained.
(ii) the ratio (M M /M P ) of the total number of moles of M in all oxides contained in the modified sulfide solid electrolyte (M M ) to the total number of moles of phosphorus atoms in the sulfide solid electrolyte ( M P ) is greater than 0.010.
(iii) Only one peak is observed within the range of 29.7±0.5 deg. in an X-ray diffraction spectrum (XRD pattern), or when two or more peaks are observed, I2 / I1 is less than 1.0, where I1 is the intensity of the highest peak and I2 is the intensity of the second highest peak.
The modified sulfide solid electrolyte according to claim 11, in which the intensity ratio (peak intensity due to oxide/peak intensity due to argyrodite crystal structure) of the peak intensity due to the oxide and the peak intensity at 29.7±0.5 deg. due to the argyrodite crystal structure (peak intensity due to argyrodite crystal structure) in an X-ray diffraction spectrum (XRD pattern) is less than 0.1.
The modified sulfide solid electrolyte according to claim 11 or 12, wherein the halogen atoms include at least one selected from chlorine atoms and bromine atoms.
The modified sulfide solid electrolyte according to any one of claims 11 to 13, in which the oxide is attached or bonded to the surface of the primary particles.
The modified sulfide solid electrolyte according to any one of claims 11 to 14, having a median diameter (D 50 ) of less than 150 μm.
16. The modified sulfide solid electrolyte of claim 14 or 15, wherein the median diameter ( D50 ) of the oxide attached or bonded to the surface of the primary particles of the modified sulfide solid electrolyte is less than 100.0 μm.
The modified sulfide solid electrolyte according to any one of claims 11 to 16, comprising an oxide in which M in the general formula M m O n is Si.
The modified sulfide solid electrolyte according to any one of claims 11 to 17, which does not include an oxide in which M in the general formula M m O n is Ti.
An electrode mixture comprising the modified sulfide solid electrolyte according to any one of claims 11 to 18 and an electrode active material.
A lithium ion battery comprising at least one of the modified sulfide solid electrolyte described in any one of claims 11 to 18 and the electrode mixture described in claim 19.