JP2016027554A - Solid electrolyte - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid electrolyte for a new battery excellent in ionic conductivity.SOLUTION: There is provided a solid electrolyte which contains Liions, PSions and polyatomic ions having an ionic radius of 1.5 to 3.1 Å other than the PSions and is amorphous, wherein the polyatomic ions are one or more selected from SiF62-, SCN-, BF4- and AlO2-, the polyatomic ions have an ionic radius of 1.6 to 3.0 Å and the ionic conductivity of the polyatomic ions is 1.0×10to 8.0×10S/cm.SELECTED DRAWING: None

Description

  The present invention relates to a solid electrolyte and a method for producing the same.

In recent years, there has been an increasing demand for lithium ion secondary batteries used in personal digital assistants, portable electronic devices, small household power storage devices, motorcycles powered by motors, electric vehicles, hybrid electric vehicles, and the like.
As a method for ensuring the safety of a lithium ion secondary battery, an all-solid secondary battery using an inorganic solid electrolyte instead of an organic electrolyte has been studied.

  As a solid electrolyte of an all-solid secondary battery, for example, various sulfide-based solid electrolytes using sulfide as a raw material have been studied (for example, Patent Document 1).

JP 2010-199033 A

  An object of the present invention is to provide a novel solid electrolyte excellent in ionic conductivity.

According to the present invention, the following solid electrolyte and the like are provided.
1. Li ⁺ ion,
A solid electrolyte containing PS ₄ ^3- ion and polyatomic ions other than the PS ₄ ^3- ion and having an ionic radius of 1.5 to 3.1 ^３ .
2. 2. The solid electrolyte according to 1, which is amorphous.
3. The solid electrolyte according to 1 or 2, wherein the polyatomic ion is one or more selected from SiF ₆ ²⁻ , SCN ⁻ , BF ₄ ⁻ and AlO ₂ ⁻ .
4). The solid electrolyte according to any one of 1 to 3, wherein the polyatomic ion is AlO ₂ ^— .
5. The solid electrolyte according to any one of 1 to 4, wherein the polyatomic ions have an ionic radius of 1.6 to 3.0 Å.
6). The solid electrolyte according to any one of 1 to 5, wherein an ionic radius of the polyatomic ion is 1.8 to 2.8.
7). The solid electrolyte according to any one of 1 to 6, which has an ionic conductivity of 1.0 × 10 ⁻⁴ S / cm to 8.0 × 10 ⁻³ S / cm.
8). The solid electrolyte according to any one of 1 and 3 to 7, which is crystalline.
9. 9. The solid electrolyte according to 8, which contains a thiolithicone type II similar crystal phase.
10. A method for producing a solid electrolyte, comprising a step of contacting lithium sulfide, a phosphorus compound, and a compound capable of generating polyatomic ions having an ionic radius of 1.5 to 3.1.
11. 11. The method for producing a solid electrolyte according to 10, wherein the phosphorus compound is phosphorus sulfide.
12 12. The method for producing a solid electrolyte according to 11, wherein the phosphorus sulfide is diphosphorus pentasulfide.
13. The method for producing a solid electrolyte according to any one of 10 to 12, wherein the polyatomic ion is one or more selected from SiF ₆ ²⁻ , SCN ⁻ , BF ₄ ⁻ and AlO ₂ ⁻ .
14 Method for producing a solid electrolyte according to any one of 10 to 13 is ^- the polyatomic ions AlO _2.
15. The method for producing a solid electrolyte according to any one of 10 to 14, wherein the compound capable of generating the polyatomic ion is a lithium salt of the polyatomic ion.
16. The method for producing a solid electrolyte according to any one of 10 to 15, wherein the polyatomic ion has an ionic radius of 1.6 to 3.0 Å.
17. The method for producing a solid electrolyte according to any one of 10 to 16, wherein an ionic radius of the polyatomic ion is 1.8 to 2.8.
18. The manufacturing method of the solid electrolyte in any one of 10-17 including the process of further heat-processing the glass obtained by the said contact.
19. 19. The method for producing a solid electrolyte according to 18, wherein the heat treatment is performed at a glass transition temperature or higher and a crystallization temperature or lower.
20. 20. The method for producing a solid electrolyte according to 18 or 19, wherein the heat treatment is performed for 0.01 to 15 hours.
21. Including a positive electrode layer, a solid electrolyte layer, and a negative electrode layer;
A battery in which at least one of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer includes the solid electrolyte according to any one of 1 to 9.

  According to the present invention, a novel solid electrolyte excellent in ionic conductivity can be provided.

[Solid electrolyte]
The solid electrolyte of the present invention includes Li ⁺ ions, PS ₄ ^3- ions, and polyatomic ions having an ionic radius of 1.5 to 3.1 以外 other than PS ₄ ^3- ions.

In the solid electrolyte containing PS ₄ ^3- , an anion having a size equal to or smaller than that of PS ₄ ^3- contained in the solid electrolyte is dispersed in the solid electrolyte, so that these are taken into the solid electrolyte, and the structure of the solid electrolyte The ionic conductivity can be improved by causing a change in the.
In addition, since various atoms can be combined by using a polyatomic ion component, a desired size can be easily obtained.

PS ₄ ³⁻ can be generated in a solid electrolyte by including a compound capable of generating PS ₄ ³⁻ , such as a lithium salt of PS ₄ ³⁻ (Li ₃ PS ₄ ).
Moreover, by reacting lithium sulfide and a phosphorus compound (preferably diphosphorus pentasulfide) as in the production method described later, these can be reacted to produce PS ₄ ³⁻ .

The polyatomic ion is not particularly limited as long as it has an ionic radius of 1.5 to 3.1, but is preferably an anion and selected from SiF ₆ ²⁻ , SCN ⁻ , BF ₄ ⁻ and AlO ₂ ^−. 1 or more is more preferable, and AlO ₂ ^— is more preferable.

  The ionic radius of the polyatomic ions is preferably 1.6 to 3.0 and more preferably 1.8 to 2.8. For example, they are 2.0? -2.8? And 2.2? -2.8 ?. If it is this range, a polyatomic ion will be easy to be taken in in the structure of a solid electrolyte, and ionic conductivity will improve more.

Polyatomic ions can be generated in the solid electrolyte by using a compound (compound A) that can generate polyatomic ions.
The compound capable of generating a polyatomic ion is not particularly limited as long as it is ionized to generate the above polyatomic ion. For example, alkali metal salts such as lithium salt, sodium salt, potassium salt and the like of the above polyatomic ion can be used. Can be mentioned. Specifically, Li ₂ SiF ₆ , Na ₂ SiF ₆ , K ₂ SiF ₆ , KNaSiF ₆ , LiSCN, NaSCN, KSCN, LiBF ₄ , NaBF ₄ , KBF ₄ , LiAlO ₂ , NaAlO ₂ , KAlO _{2 and the} like can be mentioned. .

The ion radius of polyatomic ions is obtained as follows.
Considering that a substance containing polyatomic ions is freely rotating in a crystal, an ion radius approximated to a sphere is obtained. Specifically, the ion radius of polyatomic ions is obtained by the following formula (I) based on the ion radius calculation method by Pauling. The internuclear distance can be obtained using free software Venus (developer: Mr. Fujio Izumi).
Ion radius of polyatomic ion = internuclear distance-radius of cation (I)

  When the internuclear distance or the ionic radius of polyatomic ions is two or more numerical values, an average value is used as in a specific example described later.

Specifically, the ion radii of PS ₄ ³⁻ , SiF ₆ ²⁻ , BF ₄ ⁻ , AlO ₂ ⁻ and SCN ⁻ are calculated as follows. The following crystal structure data was used for the calculation, and the Pauling value (6-coordinate) was used for the ion radius of the cation.

PS ₄ ³⁻ : γ-Li ₃ PS ₄ (K.Homma, M.Yonemura, T.Kobayashi, M.Hirayama, R.Kanno Solid State Ionics 182,53 (2011))
SiF ₆ ²⁻ : KNaSiF ₆ (J. Fischer, K. Kramer, Mat. Res. Bull. 26,925 (1991))
BF ₄ ⁻ : NaBF ₄ (G. Brunton, Acta Cryst, B24, 1703 (1968))
AlO ₂ ⁻ : NaAlO ₂ (JAKauduk, S.Pei, J. Solid State Chem. 115, 126 (1995))
SCN ⁻ : NaSCN (JWBats, P. Coppens, A. Kvick, Acta Crystallogr. B33, 1534 (1977)

・ PS ₄ ³⁻ (γ-Li ₃ PS ₄ )
Li-P internuclear distance 3.64Å, 3.74Å (average 3.69Å)
Li ⁺ ion radius 0.6Å
PS ₄ ^3- ionic radius = 3.69-0.6 = 3.09?

・ SiF ₆ ²⁻ (KNaSiF ₆ )
K-Si internuclear distance 3.78 mm
K ⁺ ion radius 1.33Å
Na-Si internuclear distance of 3.21 mm
Na ⁺ ionic radius 0.95Å
SiF ₆ ^2-ionic radius (K-Si) = 3.78-1.33 = 2.45Å
SiF ₆ ²⁻ ionic radius (Na—Si) = 3.21−0.95 = 2.26 Å
SiF ₆ ²⁻ ionic radius (average) = 2.36 Å

· _{BF ⁴} - (NaBF ⁴⁾
Na-B internuclear distance of 3.10 mm, 3.16 mm (average 3.13 mm)
Na ⁺ ionic radius 0.95Å
Ion radius of BF ₄ ⁻ = 3.13−0.95 = 2.18Å

・ AlO ₂ ⁻ (NaAlO ₂ )
Na-Al internuclear distance of 3.22 mm, 3.37 mm (average 3.30 mm)
Na ⁺ ionic radius 0.95Å
The ionic radius of AlO ₂ ⁻ = 3.30−0.95 = 2.35 Å

· ^SCN - (NaCSN)
Na-C internuclear distance 3.71 mm, 3.44 mm (average 3.58 mm)
Na ⁺ ionic radius 0.95Å
SCN ^- ion radius = 3.58-0.95 = 2.63Å

It can be judged from the results of XRD, Raman spectroscopy, solid-NMR, and the like and from the plurality of results that PS ₄ ³⁻ and the above polyatomic ions are contained in the solid electrolyte.

The solid electrolyte of the present invention may be amorphous (amorphous) or crystalline (crystalline), and is preferably amorphous.
Glass ceramics (crystals) can be produced by heat-treating solid electrolyte glass (non-crystal) at a temperature above the glass transition temperature, and preferably by heat treatment at a temperature above the glass transition temperature and below the crystallization temperature.
As heat processing time, it is 0.01 to 15 hours, for example, Preferably it is 0.1 to 10 hours.
In the solid electrolyte of the present invention, the polyatomic ions contained in the solid electrolyte glass are contained as they are without changing even if the solid electrolyte glass ceramics is formed by the heat treatment.

Here, “glass” and “glass ceramics” representing the state of the solid electrolyte are defined as follows.
That is, “glass” refers to a solid electrolyte in which the X-ray diffraction pattern is a halo pattern that does not substantially show a peak other than the peak derived from the solid electrolyte raw material in the X-ray diffraction measurement. In addition, the presence or absence of the peak derived from a solid electrolyte raw material shall not be ask | required.
“Glass ceramics” refers to a solid electrolyte in which a peak derived from the solid electrolyte is observed. In addition, the presence or absence of the peak derived from a solid electrolyte raw material shall not be ask | required. That is, the glass ceramic includes a crystal structure derived from a solid electrolyte, and a part thereof may be a crystal structure derived from a solid electrolyte, or a whole may be a crystal structure derived from a solid electrolyte. Glass ceramics can be obtained, for example, by crystallizing glass.

As the crystal structure contained in the glass ceramic, Li ₃ PS ₄ crystal structure, Li ₄ P ₂ S ₆ crystal structure, Li ₇ PS ₆ crystal structure, Li ₇ P ₃ S ₁₁ crystal structure, Li _4-x Ge _1-x P _x S ₄ series thiolysicon type II crystal structure (see Kanno et al., Journal of The Electrochemical Society, 148 (7) A742-746 (2001)). These structures can be confirmed by X-ray diffraction (XRD) measurement.
The crystallinity is usually 20% or more and 99% or less, for example, 25% or more and 90% or less, and 30% or more and 80% or less.

The thiolithicone type II crystal structure has so far been deposited by replacing a part of Li ₃ PS ₄ with Ge (Li _4-x Ge _1-x P _x S ₄ system) to form a high ion conductive crystal. It was difficult with other elements. On the other hand, in the present invention, a high ion conductive crystal similar to the above can be precipitated in the obtained solid electrolyte glass ceramic by heat-treating the solid electrolyte glass containing polyatomic ions.
Here, “similar” means that, for example, the value of 2θ is slightly shifted or the peak intensity is slightly changed in the XRD pattern, and the effect of high ion conductivity is obtained. It means that the XRD pattern is substantially the same.

The solid electrolyte of the present invention can be produced by a solid electrolyte production method described later.
The solid electrolyte of the present invention is excellent in ionic conductivity, for example, 1.0 × 10 ^{−4 to} 8.0 × 10 ⁻³ S / cm, 1.0 × 10 ^{−4 to} 5.0 × 10 ⁻³ S / cm. 2.0 × 10 ^{−4 to} 5.0 × 10 ⁻³ S / cm. Ionic conductivity is measured by the method described in the examples.

[Method for producing solid electrolyte]
The method for producing a solid electrolyte of the present invention includes a step of contacting lithium sulfide (Li ₂ S), a phosphorus compound, and a compound (compound A) capable of generating polyatomic ions having an ionic radius of 1.5 to 3.1 接触. Compound A is the same as described above.

  Lithium sulfide can be used without particular limitation, but high purity is preferred. Lithium sulfide can be produced, for example, by the methods described in JP-A-7-330312, JP-A-9-283156, JP-A 2010-163356, and Japanese Patent Application No. 2009-233892.

  The lithium sulfide preferably has a total lithium oxide lithium salt content of 0.15% by mass or less, more preferably 0.1% by mass or less, and a lithium N-methylaminobutyrate content. The content is preferably 0.15% by mass or less, more preferably 0.1% by mass or less. When the total content of the lithium salt of sulfur oxide is 0.15% by mass or less, the solid electrolyte obtained by the melt quenching method or the mechanical milling method becomes a glassy electrolyte (fully amorphous). On the other hand, when the total content of the lithium salt of sulfur oxide exceeds 0.15% by mass, the obtained electrolyte may become a crystallized product from the beginning. The solid electrolyte, which is a crystallized product before the heat treatment, may have a low ionic conductivity and may not be expected to improve the ionic conductivity by the heat treatment.

  In addition, when the content of lithium N-methylaminobutyrate is 0.15% by mass or less, a deteriorated product of lithium N-methylaminobutyrate does not deteriorate the cycle performance of the lithium ion battery. When lithium sulfide with reduced impurities is used, a high ion conductive electrolyte can be obtained.

When lithium sulfide is produced based on the above-mentioned JP-A-7-330312 and JP-A-9-283156, it is preferable to purify the lithium sulfide because it contains a lithium salt of a sulfur oxide.
On the other hand, lithium sulfide produced by the method for producing lithium sulfide described in JP-A-2010-163356 may be used without purification because it contains a very small amount of sulfur oxide lithium salt or the like.
As a preferable purification method, for example, a purification method described in International Publication No. WO2005 / 40039 and the like can be mentioned. Specifically, the lithium sulfide obtained as described above is washed at a temperature of 100 ° C. or higher using an organic solvent.

As the phosphorus compound, phosphorus sulfide is preferable, and phosphorus pentasulfide (P ₂ S ₅ ) is more preferable. As long as diphosphorus pentasulfide is manufactured and sold industrially, it can be used without particular limitation.

  The contacting step includes an MM (mechanical milling) method, a melting method, a method of bringing a raw material into contact with a hydrocarbon solvent (International Publication No. 2009/047977), a means for bringing the raw material into contact with a hydrocarbon solvent, and a pulverizing and synthesizing means. Can be carried out by a method of alternately carrying out the above (Japanese Patent Laid-Open No. 2010-140893), a method of performing a pulverizing synthesis step after a step of contacting a raw material in a solvent (International Publication No. 2013/042371), or other methods. .

In the above manufacturing method, Li ₂ S, phosphorus compound and compound A may be contacted at once, or Li ₂ S and phosphorus compound are contacted to prepare a solid electrolyte (sulfide-based solid electrolyte), and the sulfide The physical solid electrolyte and compound A may be contacted.
In any case, a solid electrolyte in which polyatomic ions derived from the compound A are dispersed in a sulfide-based solid electrolyte using Li ₂ S and a phosphorus compound as raw materials is obtained.
The definition of “sulfide solid electrolyte” itself is generally defined as a substance that contains elemental sulfur, is solid at room temperature, and has ionic conductivity. In the present invention, it is preferable that the right range of the sulfide solid electrolyte is a sulfide solid electrolyte containing lithium element, sulfur element, and phosphorus element.
Hereinafter, a sulfide-based solid electrolyte using Li ₂ S and a phosphorus compound as raw materials will be described.

The molar ratio between Li ₂ S and the phosphorus compound is preferably 50:50 to 95: 5.
The sulfide-based solid electrolyte of Li 2 _S and a phosphorus compound as a raw material, at least Li 2 _S and phosphorus compound as the raw material sulfide-based solid electrolyte is preferable.
As a sulfide-based solid electrolyte using at least Li ₂ S and a phosphorus compound as raw materials, the molar ratio of Li ₂ S and phosphorus compound used as raw materials is Li ₂ S: P ₂ S ₅ = 60: 40 to 82:18. preferably the sulfide-based solid electrolyte, more preferably, Li ₂ S and the molar ratio _Li 2 phosphorus compound S: phosphorus compounds = 65: 35-82: 18 is a sulfide-based solid electrolyte, for example, Li ₂ S: phosphorus compound _{= 68: 32~82: 18, Li} 2 S: phosphorus compound = 72: 38 to 78: a 22.

Moreover, as the sulfide-based solid electrolyte using at least Li ₂ S and a phosphorus compound as raw materials, a sulfide-based solid electrolyte using Li ₂ S and a phosphorus compound as raw materials is preferable.
Li ₂ S and a sulfide-based solid electrolyte phosphorus compound as the raw material, is used as a raw material Li ₂ S and 2 molar ratio _Li of the phosphorus compound S: phosphorus compounds = 60: 40 to 82: 18 to become sulfide solid electrolyte, more preferably, Li ₂ S and the molar ratio _Li 2 phosphorus compound S: phosphorus compounds = 65: 35 to 82: a 18.
That, Li contained in the sulfide-based solid electrolyte, the P and S, in the case in terms of the ratio of Li ₂ S and a phosphorus compound, the molar ratio of _Li 2 S: phosphorus compound = 60: 40 to 82: the 18 preferably the sulfide-based solid electrolyte, more preferably, Li ₂ S and the molar ratio _Li 2 phosphorus compound S: phosphorus compounds = 65: 35-82: 18 is a sulfide-based solid electrolyte, for example, Li ₂ S: phosphorus compound _{= 68: 32~82: 18, Li} 2 S: phosphorus compound = 72: 38 to 78: a 22.

The sulfide-based solid electrolyte of Li 2 _S and a phosphorus compound as a raw material, other Li 2 _S and a phosphorus compound, may be further added a halide. Examples of the halide include LiI, LiBr, LiCl and the like. Specific examples of the solid electrolyte to which a halide is added include a sulfide-based solid electrolyte containing Li, P, S and I, a sulfide-based solid electrolyte containing Li, P, S and Br, Li, P, S and Examples thereof include sulfide-based solid electrolytes containing Cl.

The ratio of the molar amount of halide to the total molar amount of Li ₂ S and phosphorus compound is preferably [Li ₂ S + phosphorus compound]: halide = 50: 50 to 99: 1, more preferably [Li ₂ S + phosphorus compound]: halide = 60: 40 to 98: 2, more preferably [Li ₂ S + phosphorus compound]: halide = 70: 30 to 98: 2, particularly preferably [Li ₂ S + phosphorus]. Compound]: halide = 72: 28 to 98: 2, for example, [Li ₂ S + phosphorus compound]: halide = 72: 28 to 90:10, [Li ₂ S + phosphorus compound]: halide = 75: 25 ~ 88: 12.

Specific examples of solid electrolytes using Li ₂ S and phosphorus compounds as raw materials include Li ₂ S—P ₂ S ₅ , LiI—Li ₂ S—P ₂ S ₅ , LiBr—Li ₂ S—P ₂ S ₅ , Examples thereof include sulfide-based solid electrolytes such as LiCl—Li ₂ S—P ₂ S ₅ and Li ₃ PO ₄ —Li ₂ S—Si ₂ S.

The ratio of the molar amount of compound A to the total molar amount of Li ₂ S and phosphorus compound is [Li ₂ S + phosphorus compound]: compound A = 99: 1 to 60:40, more preferably [Li ₂ S + phosphorus]. Compound]: Compound A = 95: 5 to 70:30.

  When the solid electrolyte is crystalline, the amorphous solid electrolyte obtained above is heated to obtain a crystallization complex.

  The solid electrolyte of the present invention can be used for a secondary battery, such as a portable information terminal, a portable electronic device, a small electric power storage device for home use, a motorcycle using a motor as a power source, an electric vehicle, a hybrid electric vehicle, etc. It can be used as a battery.

Production Example 1 [Production of lithium sulfide]
(1) Production of lithium sulfide (Li ₂ S) In a 10 liter autoclave equipped with a stirring blade, N-methyl-2-pyrrolidone (NMP) 3326.4 g (33.6 mol) and lithium hydroxide 287.4 g (12 mol) ) And heated to 300 rpm and 130 ° C. After the temperature rise, hydrogen sulfide was blown into the liquid at a supply rate of 3 liters / minute for 2 hours.
Subsequently, this reaction solution was heated in a nitrogen stream (200 cc / min) to dehydrosulfide a part of the reacted hydrogen sulfide. As the temperature increased, water produced as a by-product due to the reaction between hydrogen sulfide and lithium hydroxide started to evaporate, but this water was condensed by the condenser and extracted out of the system. While water was distilled out of the system, the temperature of the reaction solution rose, but when the temperature reached 180 ° C., the temperature increase was stopped and the temperature was kept constant. After the dehydrosulfurization reaction was completed (about 80 minutes), the reaction was completed 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) above, 100 mL of dehydrated NMP was added and stirred at 105 ° C. for about 1 hour. . NMP was decanted at that temperature. Further, 100 mL of NMP was added, stirred at 105 ° C. for about 1 hour, NMP was decanted at that temperature, and the same operation was repeated a total of 4 times. After completion of the decantation, lithium sulfide was dried at 230 ° C. (temperature higher than the boiling point of NMP) under a nitrogen stream for 3 hours under normal pressure. The impurity content in the obtained lithium sulfide was measured.
Incidentally, lithium sulfite _(Li 2 _SO 3), the content of each sulfur oxide lithium sulfate _(Li 2 SO ₄₎ and lithium thiosulfate _{(Li 2 S 2 O 3)} , and N- methylamino acid lithium (LMAB) Was quantified by ion chromatography. As a result, the total content of sulfur oxides was 0.13% by mass, and LMAB was 0.07% by mass.

Production Example 2 [Production of solid electrolyte]
0.383 g (0.00833 mol) of lithium sulfide produced in Production Example 1 and 0.618 g (0.00278 mol) of diphosphorus pentasulfide (manufactured by Aldrich) were mixed well. Then, the mixed powder, 10 zirconia balls having a diameter of 10 mm, and a planetary ball mill (manufactured by Fritsch Co., Ltd .: Model No. P-7) are put into an alumina pot and completely sealed, and the alumina pot is filled with nitrogen, The atmosphere was nitrogen.

For the first few minutes, the planetary ball mill was rotated at a low speed (100 rpm) to sufficiently mix lithium sulfide and diphosphorus pentasulfide. Thereafter, the rotational speed of the planetary ball mill was gradually increased to 370 rpm. Mechanical milling was performed for 20 hours at a rotational speed of the planetary ball mill at 370 rpm. As a result of evaluating the mechanically milled white yellow powder by X-ray measurement, it was confirmed that the powder was vitrified (sulfide glass). ³¹ PNMR measurement showed a main peak at 83.0 ppm.

Example 1
0.3094 g of LiAlO ₂ , 0.6470 g of Li ₂ S (manufactured in Production Example 1), and 1.0433 g so as to have a ratio (mol%) of 20LiAlO ₂ : 60Li ₂ S: 20P ₂ S ₅ P ₂ S ₅ (manufactured by Aldrich) was mixed, and 1 g of the mixture was put into a 45 ml alumina pot. Ten zirconia balls (diameter 10 mm) were put in this, and reacted by performing mechanical milling at 370 rpm for 40 hours using a planetary ball mill (Fritche P-7). After completion of the reaction, a sample was taken out and the ionic conductivity was measured. The results are shown in Table 1. Moreover, as a result of evaluating the sample by X-ray measurement, it was confirmed that the sample was vitrified.

In addition, ion conductivity (Li ion conductivity) was measured as follows.
The composite was filled in a tablet molding machine, and a pressure of 360 MPa was applied to obtain a molded product. Furthermore, an electrode was formed by applying and drying carbon paste on both surfaces of the molded body, and a molded body for measuring conductivity (diameter of about 10 mm, thickness of about 1 mm) was produced. The molded body was subjected to ionic conductivity measurement by AC impedance measurement. The conductivity value was a value at 25 ° C.

Comparative Example 1
The solid electrolyte obtained in Production Example 2 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

  From Table 1, it can be seen that the solid electrolyte of the present invention containing a specific polyatomic ion or a compound capable of generating the same has excellent ionic conductivity.

Example 2
The glass electrolyte obtained in Example 1 was heat treated at 225 ° C., which is 5 ° C. lower than the crystallization temperature (Tc), for 0.5 hour to form glass ceramics.
As a result of XRD measurement of the obtained solid electrolyte glass ceramic, it was confirmed that a thiolithicone type II similar crystal phase was precipitated. Moreover, when the ionic conductivity was measured like Example 1 about the obtained solid electrolyte glass ceramics, conductivity was 0.51 mS / cm.

Example 3
The glass electrolyte obtained in Example 1 was heat treated at 225 ° C., which is 5 ° C. lower than the crystallization temperature (Tc), for 1 hour to form glass ceramics.
As a result of XRD measurement of the obtained solid electrolyte glass ceramic, it was confirmed that a thiolithicone type II similar crystal phase was precipitated. Further, when the ionic conductivity of the obtained solid electrolyte glass ceramics was measured in the same manner as in Example 1, the conductivity was 0.44 mS / cm.

  The battery using the solid electrolyte of the present invention can be used as a battery for a portable information terminal, a portable electronic device, a small household power storage device, a motorcycle using a motor as a power source, an electric vehicle, a hybrid electric vehicle, or the like.

Claims (21)

Li ⁺ ion,
A solid electrolyte containing PS ₄ ^3- ion and polyatomic ions other than the PS ₄ ^3- ion and having an ionic radius of 1.5 to 3.1 ^３ .   The solid electrolyte according to claim 1, which is amorphous. The solid electrolyte according to claim 1, wherein the polyatomic ion is one or more selected from SiF ₆ ²⁻ , SCN ⁻ , BF ₄ ⁻ and AlO ₂ ⁻ . The solid electrolyte according to claim 1, wherein the polyatomic ion is AlO ₂ ^— .   The solid electrolyte according to any one of claims 1 to 4, wherein the polyatomic ion has an ionic radius of 1.6 to 3.0 請求.   The solid electrolyte according to claim 1, wherein the polyatomic ion has an ionic radius of 1.8 to 2.8 Å. The solid electrolyte according to claim 1, wherein the ionic conductivity is 1.0 × 10 ⁻⁴ S / cm to 8.0 × 10 ⁻³ S / cm.   The solid electrolyte according to claim 1, which is crystalline.   The solid electrolyte according to claim 8, comprising a thiolithicone type II-like crystal phase.   A method for producing a solid electrolyte, comprising a step of contacting lithium sulfide, a phosphorus compound, and a compound capable of generating polyatomic ions having an ionic radius of 1.5 to 3.1.   The method for producing a solid electrolyte according to claim 10, wherein the phosphorus compound is phosphorus sulfide.   The method for producing a solid electrolyte according to claim 11, wherein the phosphorus sulfide is diphosphorus pentasulfide. The method for producing a solid electrolyte according to claim 10, wherein the polyatomic ion is one or more selected from SiF ₆ ²⁻ , SCN ⁻ , BF ₄ ⁻ and AlO ₂ ⁻ . The method for producing a solid electrolyte according to claim 10, wherein the polyatomic ion is AlO ₂ ^— .   The method for producing a solid electrolyte according to claim 10, wherein the compound capable of generating the polyatomic ion is a lithium salt of the polyatomic ion.   The method for producing a solid electrolyte according to any one of claims 10 to 15, wherein the polyatomic ion has an ionic radius of 1.6 to 3.0 請求.   The method for producing a solid electrolyte according to any one of claims 10 to 16, wherein an ion radius of the polyatomic ion is 1.8 to 2.8.   The manufacturing method of the solid electrolyte in any one of Claims 10-17 including the process of further heat-processing the glass obtained by the said contact.   The method for producing a solid electrolyte according to claim 18, wherein the heat treatment is performed at a glass transition temperature or more and a crystallization temperature or less.   The method for producing a solid electrolyte according to claim 18 or 19, wherein the heat treatment is performed for 0.01 hours to 15 hours. Including a positive electrode layer, a solid electrolyte layer, and a negative electrode layer;
A battery in which at least one of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer includes the solid electrolyte according to claim 1.