JP2017183210A - Sulfide solid electrolyte, electrode mixture, and lithium ion battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sulfide solid electrolyte that has excellent stability and also has high ionic conductivity.SOLUTION: A sulfide solid electrolyte includes lithium, phosphorus and sulfur, with 50 mol% or more and 90 mol% or less of phosphorus included in PSstructure.SELECTED DRAWING: None

Description

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

  With the recent development of mobile communication and information electronic equipment, demand for high-capacity and lightweight lithium ion secondary batteries tends to increase. Most electrolytes exhibiting high lithium ion conductivity at room temperature are liquids, and many of the commercially available lithium ion secondary batteries use organic electrolytes. In the lithium ion secondary battery using this organic electrolyte, there is a risk of leakage, ignition and explosion, and a battery with higher safety is desired. In response to the above demand, an all-solid battery using a sulfide solid electrolyte has been developed.

One of the sulfide solid electrolytes is a sulfide solid electrolyte having a Li ₄ P ₂ S ₆ crystal structure (Patent Document 1). Li ₄ P ₂ S ₆ crystal structure is considered to be an unfavorable crystal component for improving ion conductivity (Patent Document 2).

JP 2002-109955 A JP 2008-120666 A

Although the Li ₄ P ₂ S ₆ crystal structure has low ion conductivity, the P ₂ S ₆ ^4- structure that is the basis of the crystal structure is excellent in structural stability, such as having no cross-linking sulfur. it is conceivable that.
An object of the present invention is to provide a sulfide solid electrolyte having excellent stability and high ion conductivity.

The inventors of the present invention have clarified that, among the known sulfide solid electrolytes, those containing many P ₂ S ₆ ⁴⁻ structures are Li ₄ P, which is a low ion conductive phase, in the process of synthesis. A problem has been discovered that a large amount of ₂ S ₆ crystal structure is generated. As a result of intensive studies, the inventors have found the presence of a sulfide solid electrolyte having high ion conductivity despite containing a large amount of P ₂ S ₆ ⁴⁻ structure.
According to the present invention, the following sulfide solid electrolyte and the like are provided.
1. A sulfide solid electrolyte containing lithium, phosphorus and sulfur, wherein 50 mol% or more and 90 mol% or less of the phosphorus is contained in a P ₂ S ₆ ^4- structure.
2. 2. The sulfide solid electrolyte according to 1, comprising a halogen.
3. The lithium element ratio (M _Li ), phosphorus element ratio (M _P ), and sulfur element ratio (M _S ) satisfy the following formulas (1) to (3), or 1 or 2. The sulfide solid electrolyte according to 2.
0.350 ≦ M _Li ≦ 0.600 (1)
0.050 ≦ M _P ≦ 0.200 (2)
0.300 ≦ M _S ≦ 0.500 (3)
_{(Wherein, M Li} is the element ratio of lithium, _{M P} is the element ratio of phosphorus, the _{M S} represents an element ratio of sulfur.)
4). The sulfide solid electrolyte according to any one of 1 to 3, wherein a peak derived from the Li ₄ P ₂ S ₆ crystal structure is not observed in the X-ray diffraction measurement.
5. In X-ray diffraction measurement, P ₂ S ₆ ^4-a not peak derived from crystal structures to a basic unit is observed, the sulfide solid electrolyte according to any one of 1 to 4.
6). In the X-ray diffraction measurement, P _x S _y ^a- (x is an integer of 1 to 3, y is an integer of 3 to 11, and x <y. A is an integer of 3 to 7) The sulfide solid electrolyte according to any one of 1 to 5, wherein a peak derived from a crystal structure having a basic unit of 1 is not observed.
The electrode compound material containing the sulfide solid electrolyte in any one of 7.1-6, and an active material.
A lithium ion battery including at least one of the sulfide solid electrolyte according to any one of 8.1 to 6 and the electrode mixture according to 7.
The electrode compound material manufactured with the sulfide solid electrolyte in any one of 9.1-6.
10. A lithium ion battery manufactured by at least one of the sulfide solid electrolyte according to any one of 10.1 to 6, the electrode mixture according to 7, and the electrode mixture according to 9.

  According to the present invention, a sulfide solid electrolyte having excellent stability and high ion conductivity can be provided.

2 is a differential scanning calorimetry (DSC) measurement result of the sulfide solid electrolyte obtained in Example 1. 2 is an X-ray diffraction (XRD) pattern of the sulfide solid electrolyte obtained in Example 1. FIG. 3 is an XRD pattern after heat treatment of the sulfide solid electrolyte obtained in Example 1. 3 is a ³¹ P-NMR spectrum after heat treatment of the sulfide solid electrolyte obtained in Example 1. 4 is a DSC measurement result of the sulfide solid electrolyte obtained in Example 2. 3 is an XRD pattern after heat treatment of the sulfide solid electrolyte obtained in Example 2. 3 is a ³¹ P-NMR spectrum after heat treatment of the sulfide solid electrolyte obtained in Example 2. 4 is a DSC measurement result of the sulfide solid electrolyte obtained in Example 3. 3 is an XRD pattern of a sulfide solid electrolyte obtained in Example 3. 4 is an XRD pattern after heat treatment of the sulfide solid electrolyte obtained in Example 3. 3 is a ³¹ P-NMR spectrum after heat treatment of the sulfide solid electrolyte obtained in Example 3. 4 is a DSC measurement result of the sulfide solid electrolyte obtained in Example 4. 4 is an XRD pattern of the sulfide solid electrolyte obtained in Example 4. It is a XRD pattern after heat processing of the sulfide solid electrolyte obtained in Example 4. 4 is a ³¹ P-NMR spectrum after heat treatment of the sulfide solid electrolyte obtained in Example 4. 4 is a DSC measurement result of the sulfide solid electrolyte obtained in Example 5. 7 is an XRD pattern of the sulfide solid electrolyte obtained in Example 5. 7 is an XRD pattern after heat treatment of the sulfide solid electrolyte obtained in Example 5. 6 is a ³¹ P-NMR spectrum after heat treatment of the sulfide solid electrolyte obtained in Example 5. 4 is a DSC measurement result of the sulfide solid electrolyte obtained in Example 6. 7 is an XRD pattern of the sulfide solid electrolyte obtained in Example 6. It is a XRD pattern after heat processing of the sulfide solid electrolyte obtained in Example 6. It is a ³¹ P-NMR spectrum after the heat treatment of the sulfide solid electrolyte obtained in Example 6. 3 is a DSC measurement result of the sulfide glass obtained in Comparative Example 1. 3 is an XRD pattern of the sulfide glass obtained in Comparative Example 1. 3 is an XRD pattern after heat treatment of the sulfide glass obtained in Comparative Example 1. 3 is a ³¹ P-NMR spectrum after heat treatment of the sulfide glass obtained in Comparative Example 1. It is a DSC measurement result of the sulfide glass obtained in Comparative Example 2. 3 is an XRD pattern of the sulfide glass obtained in Comparative Example 2. 4 is an XRD pattern after heat treatment of the sulfide glass obtained in Comparative Example 2. 3 is a ³¹ P-NMR spectrum after heat treatment of the sulfide glass obtained in Comparative Example 2. It is a DSC measurement result of the sulfide glass obtained in Comparative Example 3. 4 is an XRD pattern of the sulfide glass obtained in Comparative Example 3. 4 is an XRD pattern after heat treatment of the sulfide glass obtained in Comparative Example 3. 4 is a ³¹ P-NMR spectrum after heat treatment of the sulfide glass obtained in Comparative Example 3.

The sulfide solid electrolyte of the present invention contains lithium, phosphorus and sulfur. _Also, P _x ^{S y a-} (where x is an integer from 1 to 3, y is an integer of 3 to 11, which is x <y .a is an integer of 3-7.) Represented by Includes structure.
The P _x S _y ^a- structure, for example, _PS ^{4 3-} _structure, P ₂ ^{S 7 4-} structures _include P ₂ ^{S 6 4-} structures. In the present _invention, P _x ^{S y a-} structure includes at least _P 2 _S ^{6 4-} _structures, including _PS ^{4 3-} structure like in addition to the P ₂ ^{S 6 4-} structures.
In the present application, the “sulfide solid electrolyte” is a substance that contains sulfur and is solid at 25 ° C. under 1 atm and has lithium ion conductivity.

The sulfide solid electrolyte of the present invention is characterized in that 50 mol% or more and 90 mol% or less of phosphorus contained in the sulfide solid electrolyte is contained in the P ₂ S ₆ ⁴⁻ structure. In the present invention, due to the high content of P ₂ S ₆ ^4- structure, it has excellent stability.
On the other hand, it has higher ionic conductivity than the sulfide solid electrolyte having a Li ₄ P ₂ S ₆ crystal structure. Of the phosphorus contained in the sulfide solid electrolyte, the phosphorus contained in the P ₂ S ₆ ⁴⁻ structure is preferably 55 mol% or more and 88 mol% or less, more preferably 57 mol% or more and 86 mol% or less, and 59 mol. It is most preferable that the amount be from 84% to 84 mol%.

In addition, in this application, the content rate (mol%) of phosphorus contained in each structure of sulfide solid electrolyte is computed from the area of the peak derived from each structure observed by ³¹ P-NMR spectrum analysis so that it may mention later. . Thus, for example, and it is a specific structure volume is very small with the sulfide solid electrolyte, a single phosphorus and phosphorus sulfide raw material, although PPS or the like sometimes remaining, ³¹ P in the measurement conditions described later -Calculated based on the area of the peak that can be observed when NMR spectrum analysis is performed, is defined as the phosphorus content (mol%) contained in each structure.

  The sulfide solid electrolyte of the present invention may or may not contain any element in addition to lithium, phosphorus and sulfur. Examples of the optional element include halogen (F, I, Br, Cl, At, etc.), B, Zn, Si, Cu, Ga, Ge, and the like. The sulfide solid electrolyte of the present invention preferably contains a halogen.

The lithium element ratio (M _Li ), phosphorus element ratio (M _P ) and sulfur element ratio (M _S ) with respect to the total of lithium, phosphorus and sulfur contained in the sulfide solid electrolyte of the present invention (Li + P + S) It is preferable to satisfy (1) to (3).
0.350 ≦ M _Li ≦ 0.600 (1)
0.050 ≦ M _P ≦ 0.200 (2)
0.300 ≦ M _S ≦ 0.500 (3)
_{(Wherein, M Li} is the element ratio of lithium, _{M P} is the element ratio of phosphorus, the _{M S} represents an element ratio of sulfur.)
More preferably, the following formula is satisfied.
0.365 ≦ M _Li ≦ 0.575
0.080 ≦ M _P ≦ 0.195
0.315 ≦ M _S ≦ 0.485
Most preferably, the following formula is satisfied.
0.380 ≦ M _Li ≦ 0.550
0.100 ≦ M _P ≦ 0.190
0.330 ≦ _{M S} ≦ 0.470

Moreover, it is preferable to make the element ratio of phosphorus contained in the sulfide solid electrolyte relatively high. Here, the relatively high element ratio of phosphorus means the following. The element ratios of lithium element, sulfur and phosphorus contained in the entire raw material of the sulfide solid electrolyte are x, y and z (x + y + z = 1), respectively, and these elements are a mixture of Li ₂ S and P ₂ S ₅ [aLi ₂ S + bP. ₂ S ₅ , (a + b = 1)], the element ratios x, y, and z are expressed by the following formulas (a) to (c).
x = 2a (a)
y = a + 5b (b)
z = 2b (c)
In the present application, the phosphorus element ratio is relatively high when the phosphorus element ratio z is higher than 2b (z> 2b).

When the sulfide solid electrolyte of the present invention contains halogen, the elemental ratio of halogen (X) (M _X = X / (Li + P + S + X)) is preferably 0.001 to 0.400, and further 0.005 Is preferably ˜0.300, more preferably 0.01 to 0.250, and particularly preferably 0.015 to 0.200.

In order to adjust the elemental composition of the sulfide solid electrolyte, for example, when using lithium sulfide and phosphorus sulfide as raw materials, further using simple phosphorus or phosphorus compounds as raw materials, the molar ratio of phosphorus is relatively high. To do. In particular, it is preferable to use simple phosphorus as a raw material.
Further, as the raw material, lithium sulfide, phosphorus sulfide, lithium halide (for example, LiI, LiBr, LiCl, LiF can be used, and one or more of them may be used) and simple phosphorus are used. May be.

In the sulfide solid electrolyte of the present invention, it is preferable that no peak derived from the Li ₄ P ₂ S ₆ crystal structure is observed in the X-ray diffraction measurement. For example, 2θ = 32.5 ± 0.5 deg is preferably not observed. Furthermore, 2θ = 16.9 ± 0.5, 27.1 ± 0.5, 40.4 ± 0.5, 51.4 ± 0.5, 52.2 ± 0.5, 59.8 ± 0. It is preferable that no peak such as 5 deg is observed.
In the X-ray diffraction measurement, a peak derived from a crystal structure having P ₂ S ₆ ^4- as a basic unit other than the Li ₄ P ₂ S ₆ crystal structure may not be observed.
Furthermore, in the X-ray diffraction measurement, a peak derived from a crystal structure having PS ₄ ^3- as a basic unit may not be observed.
Further, in the X-ray diffraction measurement, a peak derived from a crystal structure having P ₂ S ₇ ⁴⁻ as a basic unit may not be observed.

The sulfide solid electrolyte of the present invention can be produced by mixing and synthesizing raw materials containing optional elements such as lithium, phosphorus and sulfur, and the above-mentioned halogen as desired.
As raw materials, Li ₂ S (lithium sulfide), phosphorus sulfide, SiS ₂ (silicon sulfide), Li ₄ SiO ₄ (lithium orthosilicate), Al ₂ S ₃ (aluminum sulfide), simple phosphorus (P), simple sulfur (S), silicon (Si), GeS ₂ (germanium sulfide), B ₂ S ₃ (diboron trisulfide), Li ₃ PO ₄ (lithium phosphate), Li ₄ GeO ₄ (lithium germanate), Li ₂ SnO ₃ (lithium stannate), LiBO ₂ (lithium metaborate), LiAlO ₃ (lithium aluminate), LiF (lithium fluoride), LiCl (lithium chloride), LiI (lithium iodide), LiBr (lithium bromide), etc. Can be used.

Hereinafter, an example using lithium sulfide, phosphorus sulfide, simple phosphorus and lithium halide as raw materials will be described.
Lithium sulfide used as a raw material is not particularly limited, and for example, industrially available ones can be used, and Japanese Patent Application Laid-Open Nos. 7-3301212, 9-283156, 2010-163356, Lithium sulfide that can be produced by the method disclosed in JP 2011-084438 A can be used.
In JP-A-2010-163356, lithium hydroxide and hydrogen sulfide are reacted at 70 ° C. to 300 ° C. in a hydrocarbon organic solvent to produce lithium hydrosulfide, and this reaction solution is then desulfurized. Lithium sulfide is synthesized by hydrogenation. Moreover, in the said Unexamined-Japanese-Patent No. 2011-084438, lithium hydroxide and hydrogen sulfide are made to react at 10 to 100 degreeC in a water solvent, lithium lithium sulfide is produced | generated, and this reaction liquid is then dehydrosulfurized. To synthesize lithium sulfide.

  In the method for producing lithium sulfide described in JP-A-7-330312 and JP-A-9-283156, the obtained lithium sulfide contains a lithium salt of sulfur oxide and the like, and thus it is preferably purified. On the other hand, in the method for producing lithium sulfide described in JP 2010-163356 A, the obtained lithium sulfide can be used as it is without purification because it contains a very small amount of lithium oxide lithium salt or the like.

When purifying lithium sulfide, a preferable purification method includes, for example, a purification method disclosed in International Publication WO2005 / 40039, and the obtained lithium sulfide is washed with an organic solvent at a temperature of 100 ° C. or higher. To purify.
Further, the purity of the lithium sulfide is preferably 90.0% or more, more preferably 98.0% or more, more preferably 99.0% or more, and 99.9% or more. Most preferred.

There is no limitation in particular as phosphorus sulfide, For example, what was manufactured and sold industrially may be used. Specific examples include P ₂ S ₃ (phosphorus trisulfide) and P ₂ S ₅ (phosphorus pentasulfide). These phosphorus sulfides can be used alone or in combination of two or more.
The purity of phosphorus sulfide is preferably 90.0% or more, more preferably 98.0% or more, more preferably 99.0% or more, and 99.9% or more. Most preferred.

There is no limitation in particular as simple phosphorus, For example, what is manufactured and sold industrially may be used. Examples include red phosphorus, black phosphorus, purple phosphorus, and white phosphorus. Simple phosphorus can be used individually by 1 type or in combination of 2 or more types.
The purity of simple phosphorus is preferably 90.0% or more, more preferably 98.0% or more, more preferably 99.0% or more, and 99.9% or more. Most preferred.

There is no limitation in particular as lithium halide, For example, what is manufactured and sold industrially may be used. Examples thereof include LiF, LiCl, LiI, and LiBr. Lithium halides can be used alone or in combination of two or more.
Further, the purity of the lithium halide is preferably 90.0% or more, more preferably 98.0% or more, more preferably 99.0% or more, and 99.9% or more. Most preferably it is.

The ratio of lithium sulfide and phosphorus sulfide in the raw material is preferably 98 to 60 mol%: 2 to 40 mol%, preferably 95 to 62 mol%: 5 to 38 mol%, more preferably 92 to 64 mol%: 8 to 36 mol%, 90 to 66 mol%: 10 to 34 mol% is most preferable.
The amount of simple phosphorus added is, for example, when lithium sulfide, phosphorus sulfide, and red phosphorus are used as raw materials, and when the total amount of lithium sulfide, phosphorus sulfide (Li ₂ S + P ₂ S ₅ ), and red phosphorus is 100 mol% 1 mol% to 40 mol% is preferable, 2 mol% to 35 mol% is preferable, and 3 mol% to 28 mol% is more preferable.
The amount of lithium halide added is, for example, when lithium sulfide, phosphorus sulfide, and red phosphorus are used as raw materials, and the total amount of lithium sulfide, phosphorus sulfide (Li ₂ S + P ₂ S ₅ ), red phosphorus, and lithium halide is 100 mol. %, For example, it may be 0.1 mol% to 50 mol%. Moreover, 1 mol%-40 mol% may be sufficient, for example, and 3 mol%-30 mol% may be sufficient.

  As a method for producing a sulfide solid electrolyte from the above raw materials, a MM (mechanical milling) method, a melt quenching method, a method of bringing a raw material into contact in a hydrocarbon solvent (WO2009 / 047977), and a raw material in a hydrocarbon solvent. Either a method of alternately performing the contacting means and the pulverizing / synthesizing means (Japanese Patent Laid-Open No. 2010-140893) or a method of performing the pulverizing / synthesizing step after the step of contacting the raw materials in the solvent (PCT / JP2012 / 005992) may be used.

  The solvent may be a polar solvent or a nonpolar solvent. Nonpolar solvents include hydrocarbon solvents. Examples of the hydrocarbon solvent include aliphatic hydrocarbon solvents and aromatic hydrocarbon solvents, and mixing in an aromatic hydrocarbon solvent is preferable. As the aromatic hydrocarbon solvent, alkylbenzene is preferable. As the alkylbenzene, toluene is preferable.

Although the temperature at the time of manufacture does not have limitation in particular, For example, they are 0 degreeC or more and 150 degrees C or less, 5 degreeC or more and 140 degrees C or less. When using a solvent, the boiling point of the solvent or less is preferred.
The production time is not particularly limited, but is, for example, 1 hour to 72 hours, 2 hours to 48 hours.

The sulfide solid electrolyte of the present invention is obtained in the form of glass. Usually, sulfide glass is crystallized by heat treatment. Crystallization may improve ionic conductivity. On the other hand, some or all of the sulfide solid electrolyte of the present invention may not crystallize at a normal heat treatment temperature (for example, 350 ° C. or lower). Therefore, there is an advantage that the performance change due to heat is small.
Nao, sulfide solid electrolyte of the present invention, other ^P _x S _y a- structure (e.g., PS ₄ ^3- structure) also because it contains, if necessary may be heat-treated. The heat treatment temperature is preferably 160 to 350 ° C. The heating time is preferably 0.005 minutes or more and 20 hours or less. More preferably, it is 0.005 minutes or more and 10 hours or less, and particularly preferably 1 minute or more and 5 hours or less.
There is no specific specification for the temperature raising method. The temperature may be raised slowly to a predetermined temperature or heated rapidly.
Heating is preferably performed in an environment with a dew point of −40 ° C. or lower, more preferably in an environment with a dew point of −60 ° C. or lower. The atmospheric pressure during heating may be a normal pressure or a reduced pressure. The atmosphere may be in the air or an inert atmosphere.

  The sulfide solid electrolyte of the present invention can be used for a solid electrolyte layer such as a lithium ion secondary battery, a positive electrode, a negative electrode, and the like.

[Electrode compound]
The electrode mixture of the present invention includes the above-described sulfide solid electrolyte of the present invention and an active material. Or it manufactures with the sulfide solid electrolyte of this invention. When a negative electrode active material is used as the active material, a negative electrode mixture is obtained. On the other hand, when a positive electrode active material is used, it becomes a positive electrode mixture.

-Negative electrode compound material A negative electrode compound material is obtained by mix | blending a negative electrode active material with the sulfide solid electrolyte of this invention.
As the negative electrode active material, for example, a carbon material, a metal material, or the like can be used. Among these, a complex composed of two or more kinds can be used. Moreover, a negative electrode active material developed in the future can also be used.
Moreover, it is preferable that the negative electrode active material has electronic conductivity.
Examples of carbon materials include graphite (eg, artificial graphite), graphite carbon fiber, resin-fired carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-fired carbon, polyacene, pitch-based carbon. Examples thereof include fibers, vapor-grown carbon fibers, natural graphite, and non-graphitizable carbon.
Examples of the metal material include simple metals, alloys, and metal compounds. Examples of the metal simple substance include metal silicon, metal tin, metal lithium, metal indium, and metal aluminum. Examples of the alloy include an alloy containing at least one of silicon, tin, lithium, indium, and aluminum. Examples of the metal compound include metal oxides. Examples of the metal oxide include silicon oxide, tin oxide, and aluminum oxide.

The mixing ratio of the negative electrode active material and the solid electrolyte is preferably negative electrode active material: solid electrolyte = 95 wt%: 5 wt% to 5 wt%: 95 wt%, 90 wt%: 10 wt% to 10 wt%: 90 wt%. % Is more preferable, and 85% by weight: 15% by weight to 15% by weight: 85% by weight is more preferable.
When there is too little content of the negative electrode active material in a negative electrode compound material, an electrical capacity will become small. In addition, when the negative electrode active material has electronic conductivity and does not contain a conductive aid or contains only a small amount of a conductive aid, the electronic conductivity (electron conduction path) in the negative electrode is reduced, and the rate It is considered that there is a possibility that the characteristics may be lowered, or the utilization rate of the negative electrode active material may be reduced, and the electric capacity may be reduced. On the other hand, if the content of the negative electrode active material in the negative electrode mixture is too large, the ion conductivity (ion conduction path) in the negative electrode is lowered, the rate characteristics may be lowered, the utilization rate of the negative electrode active material is lowered, and We think that capacity may decrease.

The negative electrode mixture can further contain a conductive additive.
When the negative electrode active material has low electronic conductivity, it is preferable to add a conductive additive. The conductive auxiliary agent only needs to have conductivity, and its electronic conductivity is preferably 1 × 10 ³ S / cm or more, more preferably 1 × 10 ⁵ S / cm or more.
Specific examples of conductive aids are preferably carbon materials, nickel, copper, aluminum, indium, silver, cobalt, magnesium, lithium, chromium, gold, ruthenium, platinum, beryllium, iridium, molybdenum, niobium, osnium, rhodium, A substance containing at least one element selected from the group consisting of tungsten and zinc, and more preferably a carbon simple substance having a high conductivity, or a carbon material other than simple carbon; nickel, copper, silver, cobalt, magnesium, lithium, ruthenium , Gold, platinum, niobium, osnium or rhodium, simple metals, mixtures or compounds.
Specific examples of carbon materials include carbon blacks such as ketjen black, acetylene black, denka black, thermal black, and channel black; graphite, carbon fiber, activated carbon, and the like. These may be used alone or in combination of two or more. Is possible. Among these, acetylene black, denka black, and ketjen black having high electron conductivity are preferable.

  When the negative electrode mixture contains a conductive additive, the content of the conductive additive in the mixed material is preferably 1 to 40% by weight, more preferably 2 to 20% by weight. If the content of the conductive additive is too small, the electron conductivity of the negative electrode may be reduced to lower the rate characteristics, and the utilization rate of the negative electrode active material may be reduced, resulting in a decrease in electric capacity. On the other hand, when there is too much content of a conductive support agent, the quantity of a negative electrode active material and / or the quantity of a solid electrolyte will decrease. It is estimated that the electric capacity decreases when the amount of the negative electrode active material decreases. Further, when the amount of the solid electrolyte is reduced, it is considered that the ion conductivity of the negative electrode is lowered, the rate characteristics may be lowered, the utilization rate of the negative electrode active material is lowered, and the electric capacity may be lowered.

In order to tightly bind the negative electrode active material and the solid electrolyte to each other, a binder may be further included.
Binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), fluorine-containing resins such as fluorine rubber, thermoplastic resins such as polypropylene and polyethylene, ethylene-propylene-diene rubber (EPDM), and sulfonation. EPDM, natural butyl rubber (NBR) or the like can be used alone or as a mixture of two or more. In addition, an aqueous dispersion of cellulose or styrene butadiene rubber (SBR), which is an aqueous binder, can also be used.

The negative electrode mixture can be produced by mixing a solid electrolyte, a negative electrode active material, and an optional conductive additive and / or binder.
The mixing method is not particularly limited, but, for example, dry mixing using a mortar, ball mill, bead mill, jet mill, planetary ball mill, vibrating ball mill, sand mill, cutter mill; and mortar after dispersing the raw material in an organic solvent , Ball mill, bead mill, planetary ball mill, vibrating ball mill, sand mill, and wet mix, and then wet mixing to remove the solvent can be applied. Among these, wet mixing is preferable in order not to destroy the negative electrode active material particles.

-Positive electrode mixture A positive electrode mixture is obtained by mix | blending a positive electrode active material with the solid electrolyte of this invention.
The positive electrode active material is a material capable of inserting and removing lithium ions, and those known as positive electrode active materials in the battery field can be used. Moreover, the positive electrode active material developed in the future can also be used.

Examples of the positive electrode active material include metal oxides and sulfides. The sulfide includes a metal sulfide and a nonmetal sulfide.
The metal oxide is, for example, a transition metal oxide. Specifically, V ₂ O ₅ , V ₆ O ₁₃ , LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , Li (Ni _a Co _b Mn _c ) O ₂ (where 0 <a <1, 0 <b <1, 0 <c <1, a + b + c = 1), LiNi _1-Y Co _{Y 2} O ₂ , LiCo _1-Y Mn _{Y 2} O ₂ , LiNi _1-Y Mn _{Y 2} O ₂ (where 0 ≦ Y _{<1), Li (Ni a} Co b Mn c) O 4 (0 <a <2,0 <b <2,0 <c <2, a + b + c = 2), LiMn 2-Z Ni Z O 4, LiMn 2 _-Z Co _Z O ₄ (where 0 <Z <2), LiCoPO ₄ , LiFePO ₄ , CuO, Li (Ni _a Co _b Al _c ) O ₂ (where 0 <a <1, 0 <b < 1, 0 <c <1, a + b + c = 1) and the like.
Examples of the metal sulfide include titanium sulfide (TiS ₂ ), molybdenum sulfide (MoS ₂ ), iron sulfide (FeS, FeS ₂ ), copper sulfide (CuS), and nickel sulfide (Ni ₃ S ₂ ).
Other examples of the metal oxide include bismuth oxide (Bi ₂ O ₃ ) and bismuth leadate (Bi ₂ Pb ₂ O ₅ ).
Examples of non-metal sulfides include organic disulfide compounds and carbon sulfide compounds.
In addition to the above, niobium selenide (NbSe ₃ ), metal indium, and sulfur can also be used as the positive electrode active material.

The positive electrode mixture may further contain a conductive additive.
The conductive auxiliary agent is the same as the negative electrode mixture.

  The blending ratio of the solid electrolyte and the positive electrode active material of the positive electrode mixture, the content of the conductive additive, and the method for producing the positive electrode mixture are the same as those of the negative electrode mixture described above.

[Lithium ion battery]
The lithium ion battery of the present invention includes at least one of the above-described sulfide solid electrolyte and electrode mixture of the present invention. Or it manufactures with at least 1 among the sulfide solid electrolyte of this invention, and an electrode compound material.
The configuration of the lithium ion battery is not particularly limited, but generally has a structure in which a negative electrode layer, an electrolyte layer, and a positive electrode layer are laminated in this order. Hereinafter, each layer of the lithium ion battery will be described.

(1) Negative electrode layer The negative electrode layer is preferably a layer produced from the negative electrode mixture of the present invention.
Alternatively, the negative electrode layer is preferably a layer containing the negative electrode mixture of the present invention.
The thickness of the negative electrode layer is preferably from 100 nm to 5 mm, more preferably from 1 μm to 3 mm, and even more preferably from 5 μm to 1 mm.
A negative electrode layer can be manufactured by a well-known method, for example, can be manufactured by the apply | coating method and an electrostatic method (an electrostatic spray method, an electrostatic screen method, etc.).

(2) Electrolyte layer The electrolyte layer is a layer containing a solid electrolyte or a layer manufactured from a solid electrolyte. The solid electrolyte is not particularly limited, but is preferably the sulfide solid electrolyte of the present invention.
The electrolyte layer may consist only of a solid electrolyte, and may further contain a binder. As the binder, the same binder as that for the negative electrode mixture of the present invention can be used.

The thickness of the electrolyte layer is preferably 0.001 mm or more and 1 mm or less.
The solid electrolyte of the electrolyte layer may be fused. Fusion means that a part of the solid electrolyte particles is dissolved and the dissolved part is integrated with other solid electrolyte particles. The electrolyte layer may be a solid electrolyte plate, and the plate includes a case where a part or all of the solid electrolyte particles are dissolved to form a plate.
The electrolyte layer can be manufactured by a known method, and can be manufactured by, for example, a coating method or an electrostatic method (an electrostatic spray method, an electrostatic screen method, or the like).

(3) Positive electrode layer A positive electrode layer is a layer containing a positive electrode active material, Preferably it is a layer containing the positive electrode compound material of this invention, or the layer manufactured from the positive electrode compound material of this invention.
The thickness of the positive electrode layer is preferably 0.01 mm or more and 10 mm or less.
A positive electrode layer can be manufactured by a well-known method, for example, can be manufactured by the apply | coating method and an electrostatic method (an electrostatic spray method, an electrostatic screen method, etc.).

(4) Current collector The lithium ion battery of the present invention preferably further comprises a current collector. For example, the negative electrode current collector is provided on the side of the negative electrode layer opposite to the electrolyte layer side, and the positive electrode current collector is provided on the side of the positive electrode layer opposite to the electrolyte layer side.
As the current collector, a plate or foil made of copper, magnesium, stainless steel, titanium, iron, cobalt, nickel, zinc, aluminum, germanium, indium, lithium, or an alloy thereof can be used.

The lithium ion battery of the present invention can be manufactured by bonding and joining the above-described members. As a method of joining, there are a method of laminating each member, pressurizing and pressure bonding, a method of pressing through two rolls (roll to roll), and the like.
Moreover, you may join to the joining surface through the active material which has ion conductivity, and the adhesive material which does not inhibit ion conductivity.
In joining, heat fusion may be performed as long as the crystal structure of the solid electrolyte does not change.
The lithium ion battery of the present invention can also be manufactured by sequentially forming the above-described members. It can be manufactured by a known method, for example, it can be manufactured by a coating method or an electrostatic method (electrostatic spray method, electrostatic screen method, etc.).

Hereinafter, the present invention will be described in more detail with reference to examples.
The evaluation method is as follows.
(1) Ionic conductivity measurement The sulfide solid electrolyte produced in each example was filled in a tablet molding machine, and a pressure of 22 MPa was applied to obtain a molded body. Carbon was placed on both sides of the molded body as an electrode, and pressure was again applied with a tablet molding machine to prepare a molded body for measurement (diameter of about 10 mm, thickness of 0.1 to 0.2 cm). The ion conductivity of this molded body was measured by AC impedance measurement. The conductivity value was a value at 25 ° C.
In addition, in the measurement method of the ionic conductivity used in the present example, when the ionic conductivity is less than 1.0 × 10 ⁻⁶ S / cm, the ionic conductivity cannot be measured accurately, and thus cannot be measured. It was.

(2) Differential scanning calorific value (DSC) measurement It carried out in the temperature range of 50-350 degreeC by the temperature increase rate of 2 degree-C / min in dry nitrogen atmosphere. Here, since the purpose of measuring the peak is to search for the crystallization temperature, the measurement may be stopped at an arbitrary temperature before reaching 350 ° C. when the peak appears. Using a differential scanning calorimeter (Diamond DSC manufactured by Perkin Elmer), the sample was measured at about 15 mg.

(3) ³¹ P-NMR measurement About 100 mg of a powder sample was filled into an NMR sample tube, and a ³¹ P-NMR spectrum was obtained using the following apparatus and conditions. Incidentally, if there are phosphosulfurized from starting in the sulfide solid electrolyte _(P 2 _{S 5)} and _(P 2 _{S 5} there), in the absence _(P 2 _S without ₅₎ in the measurement conditions are different. Before performing this measurement, the presence or absence of P ₂ S ₅ was confirmed by separately performing XRD measurement on the powder sample. Phosphorous sulfide was not present in the sulfide solid electrolytes of Examples and Comparative Examples of the present application.
Equipment: ECZ400R equipment (manufactured by JEOL RESONANCE)
Observation nucleus: ³¹ P
Observation frequency: 161.944 MHz
Measurement temperature: room temperature Pulse series: single pulse 90 ° pulse of solid electrolyte without P ₂ S ₅
Solid electrolyte with P ₂ S ₅ 45 ° pulse used 90 ° pulse width: 3.8 μs
Wait time until the next pulse application after FID measurement:
60s _(P No 2 _{S 5)}
1500s _(P 2 _{S 5} there)
Magic angle rotation speed:
12 kHz (no P ₂ S ₅ )
15 kHz (with P ₂ S ₅ )
Integration count:
64 times (no P ₂ S ₅ )
32 times (with P ₂ S ₅ )
range of measurement:
250 ppm to -150 ppm (without P ₂ S ₅ )
350 ppm to -250 ppm (with P ₂ S ₅ )
^In the measurement of ³¹ P-NMR spectrum, the chemical shift was obtained by using (NH ₄ ) ₂ HPO ₄ (chemical shift 1.33 ppm) as an external reference.

³¹ P-NMR from the spectrum of the phosphorus contained in the sulfide solid electrolyte each _P x _S phosphorus ratio (phosphorus ratio, mol%) contained in ^{y a-} structure was measured.
_(I) P 2 Solid ³¹ P-NMR spectrum as measured in the range of 250ppm~-150ppm when P ₂ S without ₅ the sulfide solid electrolyte of _S no _5, for example, a main peak appearing in 70～120Ppm, the main A peak called a spinning sideband is observed at a chemical shift position obtained by adding or subtracting a chemical shift width corresponding to a multiple of the number of rotations of magic angle rotation from the chemical shift of the peak. The spinning sideband is a peak that occurs when the influence caused by the anisotropy of the P electron orbit attributed to the main peak cannot be completely erased by the magic angle rotation. The intensity changes according to the rotational speed. In the solid ³¹ P-NMR spectrum of the sulfide solid electrolyte without P ₂ S ₅ measured under the conditions described above, the intensity ratio of the spinning sideband to the main peak is smaller than 1/10, and the influence on the total area sum is small. Therefore, assuming that the peak of the spinning side hand is separated into each structure at the same ratio as the area ratio obtained by waveform separation of the main peak, waveform separation was performed only on the main peak, and the phosphorus ratio of each structure was obtained. In addition, the waveform separation of the main peak was performed by a non-linear least square method in which the chemical shift and the line width of each structure were within the range shown in Table 6 assuming that the peak of the structure was a Gaussian curve. As a result of this waveform separation, within the range of 70 ppm to 120 ppm, as shown in Table 1, PS ₄ ^3- structure, P ₂ S ₇ ^4- structure, P ₂ S ₆ ^4- structure (P _x S _y ^{a -} are detected peak attributed to the structure), the area of each peak was a1, a2, a3. A sum of the areas of these peaks the (= a1 + a2 + a3) was _{S a.}

Among the phosphorus contained in the sulfide solid electrolyte, the ratio of phosphorus contained in the PS ₄ ^3- structure, P ₂ S ₇ ^4- structure and P ₂ S ₆ ^4- structure (phosphorus ratio, mol%) is expressed by the following formula: I asked for it.
PS ₄ ^3- phosphorus ratio = 100 × a1 / S _a
Phosphorus ratio of P ₂ S ₆ ^4- = 100 × a2 / S _a
Phosphorus ratio of P ₂ S ₇ ^4- = 100 × a3 / S _a

_(Ii) the P 2 _{S 5} has a solid ³¹ P-NMR spectrum as measured in the range of 350ppm~-250ppm sulfide solid electrolyte when P ₂ S ₅ there _of, seen in the solid electrolyte without P 2 _{S 5} In addition to the main peak in the vicinity of 70 to 120 ppm and its spinning sideband, the main peak of P ₂ S ₅ observed in the vicinity of 44 to 64 ppm and the range of 134 to 158 ppm, −50 to −30 ppm, and −145 to −130 ppm A signal due to the spinning sideband of P ₂ S ₅ is observed. Therefore, first, integral values b1 to b6 of each peak in the region shown in Table 7 were obtained. In addition, in the solid ³¹ P-NMR spectrum obtained by measuring under the above-described measurement conditions for the sulfide solid electrolyte with P ₂ S ₅ produced by the production method described in the present application, 350 to 200 ppm of which no upper peak is observed. The amplitude fluctuation of the signal in the region was defined as the maximum noise intensity (noise level), and integration was performed only on peaks having an intensity exceeding the noise level in the chemical shift region of Table 2. Further, the sum of these integral values was S _b (= b1 + b2 + b3 + b4 + b5 + b6), and the sum of the integral values of the peaks derived from P ₂ S ₅ was S _c (= b1 + b3 + b5 + b6).

Next, the peak derived from P _x S _y ^a- structure, separated in the same manner as (i), to give the area value of each peak, and the sum S _a of the area.
PS ₄ ^3- structure, P ₂ S ₇ ^4- structure, P ₂ S ₆ ^4- structure and phosphorus ratio (mol%) of phosphorus sulfide were determined by the following formula.
PS ₄ ^3- phosphorus ratio = 100 × [a1 / S _a ] × [(b2 + b4) / S _b ]
Phosphorus ratio of P ₂ S ₆ ^4- = 100 × [a2 / S _a ] × [(b2 + b4) / S _b ]
Phosphorus ratio of P ₂ S ₇ ^4- = 100 × [a3 / S _a ] × [(b2 + b4) / S _b ]
Phosphorus sulfide phosphorus ratio = 100 × S _c / S _b

As described above, the ratio of phosphorus contained in the _P x _S ^{y a-} structure of the phosphorus contained in the sulfide solid electrolyte (phosphate ratio, mol%) ^is calculated from the 31 P-NMR spectrum. For example, if a particular P _x S _y ^a- structure present in very small amount, or, if the single phosphorus or phosphorus sulfide raw material, PPS or the like remains, it is possible that the peak caused by these can not be detected. In these cases, in the present application, the ratio of phosphorus contained in the P _x S _y ^a- structure of the phosphorus contained in the sulfide solid electrolyte (phosphate ratio, mol%) refers to the value calculated by the conditions described above Shall.

(4) X-ray diffraction (XRD) measurement From the sulfide solid electrolyte powder produced in each example, a circular pellet having a diameter of 10 mm and a height of 0.1 to 0.3 cm was formed as a sample. This sample was measured using an airtight holder for XRD without being exposed to air. The 2θ position of the diffraction peak was determined by the centroid method using the XRD analysis program JADE.
The measurement was performed under the following conditions using a powder X-ray diffraction measurement device SmartLab manufactured by Rigaku Corporation.
Tube voltage: 45kV
Tube current: 200 mA
X-ray wavelength: Cu-Kα ray (1.5418mm)
Optical system: Parallel beam method Slit configuration: Solar slit 5 °, entrance slit 1 mm, light receiving slit 1 mm
Detector: Scintillation counter Measurement range: 2θ = 10-60 °
Step width, scan speed: 0.02 °, 1 ° / min

Production Example 1
(Production of lithium sulfide (Li ₂ S))
(1) Production of lithium sulfide A 10 liter autoclave equipped with a stirring blade was charged with 3326.4 g (33.6 mol) of N-methyl-2-pyrrolidone (NMP) and 287.4 g (12 mol) of anhydrous lithium hydroxide at 300 rpm. The temperature was raised to 130 ° C. After the temperature increase, hydrogen sulfide was blown into the liquid for 2 hours at a supply rate of 3 L / min.
Subsequently, the temperature of the reaction solution was raised under a nitrogen stream (200 cc / min), and the produced lithium hydrosulfide was desulfurized to obtain lithium sulfide. As the temperature increased, water produced as a by-product due to the reaction between hydrogen sulfide and lithium hydroxide began to evaporate, and this water was condensed by a condenser and extracted out of the system. Water was distilled out of the system and the temperature of the reaction solution rose. When the temperature reached 180 ° C., the temperature increase was stopped and the temperature was kept constant. After the dehydrosulfurization reaction of lithium hydrosulfide (about 80 minutes) was completed, the reaction was terminated to obtain lithium sulfide.

(2) Purification of lithium sulfide After decanting NMP in the 500 mL slurry reaction solution (NMP-lithium sulfide slurry) obtained in (1), 100 mL of dehydrated NMP was added and stirred at 105 ° C. for about 1 hour. NMP was decanted at that temperature. The same operation was repeated 4 times in total. After completion of the decantation, 100 mL of dehydrated heptane was added, and the mixture was stirred at room temperature to remove the supernatant. This operation was repeated 5 times. The heptane slurry was collected and filtered under a nitrogen stream to remove the solvent. Vacuum drying was performed at 200 ° C. to obtain purified lithium sulfide.
When the BET specific surface area (krypton method) was evaluated, the specific surface area was 0.04 m ² / g and the pore volume was 0.001 mL / g or less.

Example 1
Lithium sulfide produced in Production Example 1 (purity 98.6%), diphosphorus pentasulfide (FS SPEC, Thermophos, purity 99.9% or more), red phosphorus (PPE02PB, manufactured by Kojundo Chemical Laboratory Co., Ltd.) , Purity 99.999% or more) and lithium bromide (lithium bromide (anhydride), Honjo Chemical Co., Ltd., purity 99.4% or more) were used as starting materials (hereinafter, in all examples) The purity of each starting material is the same). The molar ratio of lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), red phosphorus (P) and lithium bromide (LiBr) (Li ₂ S: P ₂ S ₅ : P: LiBr) is 68. .9: 7.7: 8.5: 14.9 Each raw material was mixed. Specifically, 0.4995 g of lithium sulfide, 0.2650 g of diphosphorus pentasulfide, 0.0410 g of red phosphorus, and 0.2020 g of lithium bromide were mixed to obtain a raw material mixture.
The raw material mixture and 30 g of a zirconia ball having a diameter of 10 mm were placed in a planetary ball mill (manufactured by Fritsch: Model No. P-7) made of alumina (45 mL) and completely sealed. The inside of the pot was an argon atmosphere. Mechanical milling was performed with a planetary ball mill at a rotation speed of 370 rpm for 72 hours to obtain a sulfide solid electrolyte (sulfide glass) powder.

  The differential scanning calorimetry (DSC) measurement results of the sulfide solid electrolyte obtained in Example 1 are shown in FIG. An X-ray diffraction (XRD) pattern is shown in FIG. In the DSC measurement, a clear crystallization temperature was not observed.

About 0.5 g of the sulfide solid electrolyte was heat-treated on a hot plate (manufactured by ND-1 ASONE) under a nitrogen atmosphere. Specifically, the hot plate was set to 210 ° C. in advance, and the sulfide solid electrolyte uniformly spread on the aluminum foil was placed on the hot plate and heated for 1 hour.
The ionic conductivity (σ) of the sulfide solid electrolyte after the heat treatment was measured and found to be 2.5 × 10 ⁻⁵ S / cm. FIG. 3 shows the XRD pattern of the sulfide solid electrolyte after the heat treatment. Although there are residual Li ₂ S and LiBr-derived peaks, other clear crystal structures could not be confirmed.
2 and 3, it can be confirmed that in the sulfide solid electrolyte of this example, the XRD pattern hardly changed before and after the heat treatment. In addition, although heat peaks may cause changes such as new peaks appearing and specific peak intensities increasing, it can be inferred that this is due to LiBr segregation.

The ³¹ P-NMR measurement was performed about the sulfide solid electrolyte after heat processing. The NMR spectrum is shown in FIG. As a result, the phosphorus ratio of the P ₂ S ₆ ^4- structure was 76.8 mol%, and the phosphorus ratio of the PS ₄ ^3- structure was 23.2 mol%. It was found that the P ₂ S ₆ ⁴⁻ structure occupied the majority.
Table 3 shows the element ratio of each element in the raw materials of Example 1 and Examples and Comparative Examples described later, the phosphorus ratio of the P ₂ S ₆ ^4- structure of the obtained sulfide solid electrolyte, and the ionic conductivity after heat treatment. .

Example 2
The raw materials were mixed so that the molar ratio of the raw materials (Li ₂ S: P ₂ S ₅ : P: LiBr) was 54.8: 6.1: 26.1: 13.0. Specifically, 0.4400 g of lithium sulfide, 0.2334 g of diphosphorus pentasulfide, 0.1393 g of red phosphorus, and 0.1940 g of lithium bromide were mixed to obtain a raw material mixture. A solid electrolyte was manufactured and evaluated.
The DSC measurement result of the sulfide solid electrolyte obtained in Example 2 is shown in FIG. A clear crystallization temperature was not observed.

The sulfide solid electrolyte was heat-treated in the same manner as in Example 1. The heat treatment temperature was 220 ° C. The ionic conductivity of the sulfide solid electrolyte after the heat treatment was 2.5 × 10 ⁻⁵ S / cm.
The XRD pattern of the sulfide solid electrolyte after heat treatment is shown in FIG. Although there are residual Li ₂ S and LiBr-derived peaks, other clear crystal structures could not be confirmed. In addition, although heat peaks may cause changes such as new peaks appearing and specific peak intensities increasing, it can be inferred that this is due to LiBr segregation.
^{The 31} P-NMR spectrum is shown in FIG. As a result of NMR measurement, the phosphorus ratio of the P ₂ S ₆ ^4- structure was 74.9 mol%, and the phosphorus ratio of the PS ₄ ^3- structure was 25.1 mol%. It was found that the P ₂ S ₆ ⁴⁻ structure occupied the majority.

Example 3
Each raw material was mixed so that the molar ratio of the raw materials (Li ₂ S: P ₂ S ₅ : P: LiBr) was 60.2: 15.1: 8.4: 16.4. Specifically, 0.3601 g of lithium sulfide, 0.4299 g of diphosphorus pentasulfide, 0.0332 g of red phosphorus, and 0.1824 g of lithium bromide were mixed to obtain a raw material mixture. A solid electrolyte was manufactured and evaluated.
The DSC measurement result of the sulfide solid electrolyte obtained in Example 3 is shown in FIG. An XRD pattern is shown in FIG. In DSC measurement, a clear crystallization temperature was not observed, but a minute peak was observed at around 205 ° C.

The sulfide solid electrolyte was heat-treated in the same manner as in Example 1. The heat treatment temperature was 210 ° C. The ionic conductivity of the sulfide solid electrolyte after the heat treatment was 1.8 × 10 ⁻⁴ S / cm.
The XRD pattern of the sulfide solid electrolyte after the heat treatment is shown in FIG. Although there are residual Li ₂ S and LiBr-derived peaks, other clear crystal structures could not be confirmed. In addition, although heat peaks may cause changes such as new peaks appearing and specific peak intensities increasing, it can be inferred that this is due to LiBr segregation.
^{The 31} P-NMR spectrum is shown in FIG. As a result of NMR measurement, the phosphorus ratio of the P ₂ S ₆ ^4- structure was 58.6 mol%, and the phosphorus ratio of the PS ₄ ^3- structure was 41.4 mol%. It was found that the P ₂ S ₆ ⁴⁻ structure occupied the majority.

Example 4
Each raw material was mixed so that the molar ratio of the raw materials (Li ₂ S: P ₂ S ₅ : P: LiBr) was 48.1: 12.0: 25.8: 14.1. Specifically, lithium sulfide 0.3245 g, diphosphorus pentasulfide 0.3874 g, red phosphorus 0.1156 g, and lithium bromide 0.1776 g were mixed to obtain a raw material mixture. A solid electrolyte was manufactured and evaluated.
The DSC measurement result of the sulfide solid electrolyte obtained in Example 4 is shown in FIG. An XRD pattern is shown in FIG. In the DSC measurement, a clear crystallization temperature was not observed.

The sulfide solid electrolyte was heat-treated in the same manner as in Example 1. The heat treatment temperature was 220 ° C. The ionic conductivity of the sulfide solid electrolyte after the heat treatment was 7.8 × 10 ⁻⁵ S / cm.
FIG. 14 shows an XRD pattern of the sulfide solid electrolyte after the heat treatment. Although there are residual Li ₂ S and LiBr-derived peaks, other clear crystal structures could not be confirmed. In addition, although heat peaks may cause changes such as new peaks appearing and specific peak intensities increasing, it can be inferred that this is due to LiBr segregation.
^{The 31} P-NMR spectrum is shown in FIG. As a result of NMR measurement, the phosphorus ratio of the P ₂ S ₆ ^4- structure was 74.7 mol%, and the phosphorus ratio of the PS ₄ ^3- structure was 25.3 mol%. It was found that the P ₂ S ₆ ⁴⁻ structure occupied the majority.

Example 5
Each raw material was mixed so that the molar ratio of the raw materials (Li ₂ S: P ₂ S ₅ : P: LiBr) would be 56.0: 18.7: 8.3: 17.0. Specifically, 0.3085 g of lithium sulfide, 0.4910 g of diphosphorus pentasulfide, 0.0304 g of red phosphorus, and 0.1751 g of lithium bromide were mixed to obtain a raw material mixture. A solid electrolyte was manufactured and evaluated.
The DSC measurement result of the sulfide solid electrolyte obtained in Example 5 is shown in FIG. An XRD pattern is shown in FIG. In DSC measurement, a clear crystallization temperature was not observed, but a minute peak was observed around 229 ° C.

The sulfide solid electrolyte was heat-treated in the same manner as in Example 1. The heat treatment temperature was 250 ° C. The ionic conductivity of the sulfide solid electrolyte after the heat treatment was 1.7 × 10 ⁻⁴ S / cm.
FIG. 18 shows the XRD pattern of the sulfide solid electrolyte after the heat treatment. Although there are residual Li ₂ S and LiBr-derived peaks, other clear crystal structures could not be confirmed. In addition, although heat peaks may cause changes such as new peaks appearing and specific peak intensities increasing, it can be inferred that this is due to LiBr segregation.
^{The 31} P-NMR spectrum is shown in FIG. As a result of NMR measurement, the phosphorus ratio of the P ₂ S ₆ ^4- structure was 60.3 mol%, and the phosphorus ratio of the PS ₄ ^3- structure was 39.7 mol%. It was found that the P ₂ S ₆ ⁴⁻ structure occupied the majority.

Example 6
Each raw material was mixed so that the molar ratio of the raw materials (Li ₂ S: P ₂ S ₅ : P: LiBr) was 50.5: 16.8: 16.8: 15.9. Specifically, 0.2955 g of lithium sulfide, 0.4703 g of diphosphorus pentasulfide, 0.0655 g of red phosphorus, and 0.1735 g of lithium bromide were mixed to obtain a raw material mixture. A solid electrolyte was manufactured and evaluated.
The DSC measurement result of the sulfide solid electrolyte obtained in Example 6 is shown in FIG. An XRD pattern is shown in FIG. In the DSC measurement, a clear crystallization temperature was not observed.

The sulfide solid electrolyte was heat-treated in the same manner as in Example 1. The heat treatment temperature was 250 ° C. The ionic conductivity of the sulfide solid electrolyte after the heat treatment was 8.1 × 10 ⁻⁵ S / cm.
FIG. 22 shows the XRD pattern of the sulfide solid electrolyte after the heat treatment. Although there are residual Li ₂ S and LiBr-derived peaks, other clear crystal structures could not be confirmed. In addition, although heat peaks may cause changes such as new peaks appearing and specific peak intensities increasing, it can be inferred that this is due to LiBr segregation.
^{The 31} P-NMR spectrum is shown in FIG. As a result of NMR measurement, the phosphorus ratio of the P ₂ S ₆ ^4- structure was 83.3 mol%, and the phosphorus ratio of the PS ₄ ^3- structure was 16.7 mol%. It was found that the P ₂ S ₆ ⁴⁻ structure occupied the majority.

Comparative Example 1
Each raw material was mixed so that the molar ratio (Li ₂ S: P ₂ S ₅ : LiBr) of lithium sulfide, diphosphorus pentasulfide and lithium bromide was 47.8: 31.9 :: 20.4. Specifically, a sulfide glass was produced in the same manner as in Example 1 except that 0.2016 g of lithium sulfide, 0.6418 g of diphosphorus pentasulfide, and 0.1602 g of lithium bromide were mixed to obtain a raw material mixture. evaluated.
The DSC measurement result of the sulfide glass obtained in Comparative Example 1 is shown in FIG. An XRD pattern is shown in FIG. From the DSC measurement, the crystallization temperature of the sulfide glass was 249 ° C.

The sulfide glass was heat-treated in the same manner as in Example 1. The heat treatment temperature was 260 ° C. The ionic conductivity of the sulfide after the heat treatment was not measurable.
FIG. 26 shows the XRD pattern after the heat treatment. There were peaks derived from the Li ₄ P ₂ S ₆ crystal structure at the positions of 2θ = 16.5, 26.7, 32.0, 51.2 deg. Moreover, there was a peak derived from LiBr.
25 and 26, it can be confirmed that the sulfide glass of Comparative Example 1 is crystallized by heat treatment. This is different from the result of Example 1 of the present application.
^{The 31} P-NMR spectrum is shown in FIG. Results of NMR _measurement, phosphorus ratio 94.9Mol% of P ₂ ^{S 6 4-} structures, phosphorus ratio 2.7 mol% of _PS ^{4 3-} structure, phosphorus ratio of P ₂ S ₇ ³ structure 2.0 mol%, The phosphorus ratio of the component with unknown attribution was 0.4 mol%. It was found that the P ₂ S ₆ ⁴⁻ structure occupied the majority.

Comparative Example 2
Each raw material was mixed so that the molar ratio of the raw materials (Li ₂ S: P ₂ S ₅ : P: LiBr) was 41.5: 17.8: 25.4: 15.3. Specifically, 0.2426 g of lithium sulfide, 0.4965 g of diphosphorus pentasulfide, 0.0987 g of red phosphorus, and 0.1662 g of lithium bromide were mixed to obtain a raw material mixture. A glass product was manufactured and evaluated.
The DSC measurement result of the sulfide glass obtained in Comparative Example 2 is shown in FIG. An XRD pattern is shown in FIG. In the DSC measurement, a clear crystallization temperature was not observed.

The sulfide glass was heat-treated in the same manner as in Example 1. The heat treatment temperature was 300 ° C. The ionic conductivity of the sulfide after the heat treatment was 3.6 × 10 ⁻⁶ S / cm.
FIG. 30 shows an XRD pattern of the sulfide glass after the heat treatment. There were peaks derived from the Li ₄ P ₂ S ₆ crystal structure at the positions of 2θ = 16.7, 26.9, 32.2, 40.1, 51.1, 51.8 deg. Moreover, there was a peak derived from LiBr.
From FIG. 29 and FIG. 30, in the sulfide glass of Comparative Example 2, it can be confirmed that the XRD pattern does not change much before and after the heat treatment. That is, it can be seen that a peak derived from the Li ₄ P ₂ S ₆ crystal structure is observed before the heat treatment.
^{The 31} P-NMR spectrum is shown in FIG. As a result of NMR measurement, the phosphorus ratio of the P ₂ S ₆ ⁴⁻ structure was 100 mol%.

Comparative Example 3
The raw materials were mixed so that the molar ratio of the raw materials (Li ₂ S: P ₂ S ₅ : P: LiBr) was 30.6: 13.1: 43.7: 12.6. Specifically, 0.2106 g of lithium sulfide, 0.4310 g of diphosphorus pentasulfide, 0.2000 g of red phosphorus, and 0.1620 g of lithium bromide were mixed to obtain a raw material mixture. A glass product was manufactured and evaluated.
The DSC measurement result of the sulfide glass obtained in Comparative Example 3 is shown in FIG. An XRD pattern is shown in FIG. In the DSC measurement, a clear crystallization temperature was not observed.

The sulfide glass was heat-treated in the same manner as in Example 1. The heat treatment temperature was 250 ° C. The ionic conductivity of the sulfide after the heat treatment was 2.0 × 10 ⁻⁶ S / cm.
FIG. 34 shows the XRD pattern of the sulfide glass after the heat treatment. There were peaks derived from the Li ₄ P ₂ S ₆ crystal structure at positions of 2θ = 16.6, 26.8, 32.2, 40.1, 51.1, 51.8 deg. Moreover, there was a peak derived from LiBr.
From FIG. 33 and FIG. 34, it can be confirmed that in the sulfide glass of Comparative Example 3, the XRD pattern does not change much before and after the heat treatment. That is, it can be seen that a peak derived from the Li ₄ P ₂ S ₆ crystal structure is observed before the heat treatment.
^{The 31} P-NMR spectrum is shown in FIG. As a result of NMR measurement, the phosphorus ratio of the P ₂ S ₆ ⁴⁻ structure was 100 mol%.

The sulfide solid electrolyte of the present invention can be used as a constituent material of a lithium ion battery, for example, a positive electrode, a negative electrode, an electrolyte layer, and the like.
The lithium ion battery of the present invention can be used in portable information terminals, portable electronic devices, small household power storage devices, motorcycles powered by motors, electric vehicles, hybrid electric vehicles, and the like.

Claims (10)

A sulfide solid electrolyte containing lithium, phosphorus and sulfur,
The sulfide solid electrolyte in which 50 mol% or more and 90 mol% or less of the phosphorus is contained in the P ₂ S ₆ ^4- structure.   The sulfide solid electrolyte according to claim 1, comprising a halogen. The element ratio (M _Li ) of lithium to the total of the lithium, phosphorus and sulfur, the element ratio (M _P ) of phosphorus and the element ratio (M _S ) of sulfur satisfy the following formulas (1) to (3). The sulfide solid electrolyte according to 1 or 2.
0.350 ≦ M _Li ≦ 0.600 (1)
0.050 ≦ M _P ≦ 0.200 (2)
0.300 ≦ M _S ≦ 0.500 (3)
_{(Wherein, M Li} is the element ratio of lithium, _{M P} is the element ratio of phosphorus, the _{M S} represents an element ratio of sulfur.) The sulfide solid electrolyte according to any one of claims 1 to 3, wherein a peak derived from the Li ₄ P ₂ S ₆ crystal structure is not observed in the X-ray diffraction measurement. The sulfide solid electrolyte according to any one of claims 1 to 4, wherein a peak derived from a crystal structure having P ₂ S ₆ ^4- as a basic unit is not observed in X-ray diffraction measurement. In the X-ray diffraction measurement, P _x S _y ^a- (x is an integer of 1 to 3, y is an integer of 3 to 11, and x <y. A is an integer of 3 to 7) The sulfide solid electrolyte according to any one of claims 1 to 5, wherein a peak derived from a crystal structure having a basic unit of 1 is not observed.   The electrode compound material containing the sulfide solid electrolyte in any one of Claims 1-6, and an active material.   A lithium ion battery comprising at least one of the sulfide solid electrolyte according to any one of claims 1 to 6 and the electrode mixture according to claim 7.   The electrode compound material manufactured with the sulfide solid electrolyte in any one of Claims 1-6.   A lithium ion battery produced by at least one of the sulfide solid electrolyte according to any one of claims 1 to 6, the electrode mixture according to claim 7, and the electrode mixture according to claim 9.

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