JP4996120B2 - Solid electrolyte, method for producing the same, and all-solid-state secondary battery - Google Patents

Description

  The present invention relates to a solid electrolyte, a manufacturing method thereof, and an all-solid secondary battery such as a lithium secondary battery using the solid electrolyte as a raw material.

  In the current lithium ion secondary battery, an organic electrolyte is used as an electrolyte. Although organic electrolytes exhibit high ionic conductivity, since the electrolyte is liquid and flammable, there are concerns about intrinsic safety such as leakage and ignition when used as a battery. As an electrolyte for the next generation lithium battery, development of a safer solid electrolyte is desired.

Patent Document 1 discloses that high ion conductivity is obtained by firing a sulfide-based glass having a composition of Li ₂ S: 68 to 74 mol% and P ₂ S ₅ : 26 to 32 mol% at 150 to 360 ° C. It is disclosed that a lithium ion conductive sulfide-based crystallized glass having the following can be obtained.

Although the sulfide-based crystallized glass described in Patent Document 1 has high ionic conductivity, a long time is required when the mechanical milling method is adopted for its production, and a method for producing a solid electrolyte having high ionic conductivity is required. Efficiency is not enough. This prior document also discloses a melt quench method as a method for producing a solid electrolyte having high ionic conductivity, but this method is not excellent in mass productivity. Furthermore, Patent Document 1 describes that a third component is added to Li ₂ S and P ₂ S ₅ , but there is no specific disclosure about the obtained solid electrolyte.
JP 2005-228570 A (paragraph 0017)

  The present invention has been made in view of the above-described problems, and provides a solid electrolyte having high lithium ion conductivity, excellent in mass productivity by producing raw materials in a short time, and excellent in economic efficiency. Objective.

According to this invention, the following solid electrolyte, its manufacturing method, and the all-solid-state secondary battery using the same are provided.
1. A solid electrolyte having a composition represented by the following formula (1) and showing amorphous in X-ray diffraction (CuKα: λ = 1.5418１．５).
Li _x P _y S _z A _o (1)
(In the formula, A is an element belonging to any one of groups 13, 14, 15, 16 other than P and S.
x = 9.0 to 14.0, y = 14.0 to 21.0, z = 57.0 to 71.0, and o = 0.5 to 15.0 (% by weight). )
2. It has a composition represented by the following formula (1), and in X-ray diffraction (CuKα: λ = 1.5418４), 2θ = 17.8 ± 0.3 deg, 18.2 ± 0.3 deg, 19.8 ± 0 Solid electrolyte having diffraction peaks at .3 deg, 21.8 ± 0.3 deg, 23.8 ± 0.3 deg, 25.9 ± 0.3 deg, 29.5 ± 0.3 deg, 30.0 ± 0.3 deg.
Li _x P _y S _z A _o (1)
(In the formula, A is an element belonging to any one of groups 13, 14, 15, 16 other than P and S.
x = 9.0 to 14.0, y = 14.0 to 21.0, z = 57.0 to 71.0, and o = 0.5 to 15.0 (% by weight). )
3. 3. The solid electrolyte according to 1 or 2, wherein A is one or more selected from Si, Ge, B, Al, and O.
4). The manufacturing method of the solid electrolyte of 1 which mixes the following components (a)-(c) with the following compounding ratios.
[component]
(A) Li ₂ S
(B) P ₂ S ₅ , or elemental phosphorus and elemental sulfur (c) 1 other than the above components (a) and (b), which contains any element belonging to Groups 13, 14, 15, and 16 of the periodic table Species or two or more third components [compounding ratio]
Component (a): Component (b) (molar ratio) = 65 to 75:35 to 25
4. When component (a) and component (b) are 100 mol parts in total, component (c) is 1 to 20 mol parts. 5. The method for producing a solid electrolyte according to ₄ , wherein the third component is one or more selected from Li ₄ SiO ₄ , Li ₃ PO ₄ , Li ₄ GeO ₄ , LiBO ₂ , and LiAlO ₃ .
6). The manufacturing method of the solid electrolyte of 4 or 5 manufactured by the mechanical milling method.
The manufacturing method of the solid electrolyte of 2 which heat-processes the solid electrolyte obtained by the manufacturing method in any one of 7.4-6 in 150-360 degreeC.
8). The solid electrolyte according to any one of 1 to 3, which is for a lithium secondary battery.
9. An all-solid secondary battery obtained using the solid electrolyte according to any one of 9.1 to 3 and 8.

  According to the present invention, it is possible to provide a solid electrolyte having high lithium ion conductivity, excellent in mass productivity and excellent in economic efficiency by producing a raw material in a short time.

The first solid electrolyte of the present invention has a composition represented by the following formula (1) and exhibits an amorphous shape in X-ray diffraction.
Li _x P _y S _z A _o (1)

  In Formula (1), A is an element belonging to any one of Groups 13, 14, 15, and 16 of the periodic table, and is an element other than P and S. Preferably, it is one or more elements selected from Si, Ge, B, Al and O.

In the formula (1), x, y, z, and o are weight percentages, and x = 9.0 to 14.0, y = 14.0 to 21.0, z = 57.0 to 71.0, o = 0.5-15.0, preferably x = 9.0-13.0, y = 15.0-20.0, z = 63.0-71.0, o = 0.5-9. 0.
When the composition ratio deviates from the above, the reaction does not proceed sufficiently, so that an amorphous solid electrolyte may not be obtained by X-ray diffraction, or a material that does not have high ionic conductivity even when crystallized by heat treatment or the like may be obtained.

Amorphous in X-ray diffraction means that there is no sharp peak derived from Li ₂ S in X-ray diffraction measurement. As the X-ray diffraction measurement, charts of Examples 1, 2, and 3 described later can be shown. In Example 2, a slight peak derived from Li ₂ S remains, but in the present invention, such a solid electrolyte is also an amorphous solid electrolyte by X-ray diffraction. By heat-treating an amorphous solid electrolyte by X-ray diffraction, a solid electrolyte having a high lithium ion conductivity can be obtained.
Further, quantitatively, X-ray diffraction (CuKα: λ = 1.5418４) with 2θ = 27.04 ± 0.1 deg diffraction intensity of 500 cps or less is regarded as amorphous by X-ray diffraction. .

The first solid electrolyte can be produced, for example, by mixing the following components (a) to (c) at the following blending ratio.
[component]
(A) Li ₂ S
(B) P ₂ S ₅ , or elemental phosphorus and elemental sulfur (c) 1 other than the above components (a) and (b), which contains any element belonging to Groups 13, 14, 15, and 16 of the periodic table Species or two or more third components [compounding ratio]
Component (a): Component (b) (molar ratio) = 65 to 75:35 to 25
When the total of component (a) and component (b) is 100 mol parts, component (c) is 1 to 20 mol parts

  When the compounding ratio of the component (a) and the component (b) is out of the above range, the crystal structure peculiar to the present invention is not expressed, the ionic conductivity is decreased, and sufficient performance as a solid electrolyte is not exhibited. In particular, the amount of component (a) is preferably 68 to 73 mol%, and the amount of component (b) is preferably 32 to 27 mol%.

  When the addition amount of the component (c) is out of the above range and less than 1 mol part, in the mechanical milling process described later, the efficiency of obtaining a solid electrolyte with respect to the energy input amount and the reaction time is not sufficient, and 20 mol parts In the case of exceeding, high lithium ion conductivity cannot be obtained even if the obtained solid electrolyte is heat-treated and crystallized. In particular, the amount of component (c) added is preferably 1 to 10 mole parts.

As Li ₂ S, those commercially available without particular limitation can be used, but those having high purity are preferred. For example, the Li 2 _S obtained by reacting lithium hydroxide with hydrogen sulfide in an aprotic organic solvent, an organic solvent, those purified by washing with 100 ° C. or higher temperature can be preferably used.
Specifically, in the manufacturing method disclosed in Japanese Patent Laid-Open No. 7-330312, it is preferable to produce Li ₂ S, it is obtained by purification of the Li ₂ S by the method described in International Publication WO2005 / No. 40039 preferable.

Since this Li ₂ S manufacturing method can obtain high-purity lithium sulfide by a simple means, raw material costs can be reduced. In addition, the above purification method is economically advantageous because it can remove sulfur oxide, lithium N-methylaminobutyrate (hereinafter referred to as LMAB), and the like, which are impurities contained in Li ₂ S, by a simple treatment. At the same time, the obtained solid electrolyte for a lithium secondary battery using high-purity lithium sulfide can suppress a decrease in performance due to purity, and as a result, an excellent lithium secondary battery (solid battery) can be obtained. .
Incidentally, the total amount of sulfur oxides contained in the Li ₂ S, preferably 0.15 mass% or less, LMAB is preferably not more than 0.1 mass%.

P ₂ S ₅ can be used without particular limitation as long as it is industrially manufactured and sold.
Further, instead of P ₂ S ₅ , simple phosphorus (P) and simple sulfur (S) in a corresponding molar ratio can be used. As a result, the solid electrolyte of the present invention can be produced from an easily available and inexpensive material. Simple phosphorus (P) and simple sulfur (S) can be used without particular limitation as long as they are industrially produced and sold.

The third component is preferably an inorganic compound containing oxygen, more preferably selected from boron, aluminum, silicon, phosphorus, and germanium together with oxygen, in that a solid electrolyte having high lithium ion conductivity can be obtained by heat treatment. A compound containing a seed or two or more elements, particularly preferably lithium orthooxo acid which is a compound containing lithium together with these elements. The third component is preferably one or more compounds selected from Li ₄ SiO ₄ , Li ₃ PO ₄ , Li ₄ GeO ₄ , LiBO ₂ , and LiAlO ₃ . When such lithium orthooxo acid is included, for example, glass (amorphous component) in the second solid electrolyte described later can be stabilized in the crystallized glass.

As a first method for producing a solid electrolyte of the present invention, for example, there is a mechanical milling method (hereinafter sometimes referred to as MM treatment).
It is preferable to manufacture the first solid electrolyte using the MM treatment because it can be performed at room temperature and the manufacturing process can be simplified. Furthermore, there is an advantage that it is excellent in mass productivity.

When producing the first solid electrolyte by MM treatment, it is preferable to use an atmosphere of an inert gas such as nitrogen. This is because water vapor, oxygen and the like easily react with the starting material.
In the MM treatment, it is preferable to use a ball mill. This is because large mechanical energy can be obtained.
As the ball mill, it is preferable to use a planetary ball mill. In the planetary ball mill, since the base plate revolves while the pot rotates, very high impact energy can be generated efficiently.

The conditions for the MM treatment may be appropriately adjusted depending on the equipment to be used. However, the faster the rotation speed, the faster the production rate of the first solid electrolyte, and the longer the rotation time, the more the raw material for the first solid electrolyte. Conversion is high. For example, when a general planetary ball mill is used, the rotational speed may be several tens to several hundreds of revolutions / minute, and the treatment may be performed for 0.1 hour to 10 hours. The amount of mechanical energy input is 1 to 100 kWh, preferably 6 to 50 kWh, per 1 kg of the raw material mixture. Below this, a sharp peak derived from Li ₂ S may remain, and a heat-treated product having high lithium ion conductivity may not be obtained. On the other hand, even if a longer reaction time or mechanical energy is used, no contribution to improving lithium ion conductivity is observed.

The second solid electrolyte of the present invention has a composition represented by the following formula (1), and in X-ray diffraction (CuKα: λ = 1.5418 線), 2θ = 17.8 ± 0.3 deg, 18.2 ± 0.3 deg, 19.8 ± 0.3 deg, 21.8 ± 0.3 deg, 23.8 ± 0.3 deg, 25.9 ± 0.3 deg, 29.5 ± 0.3 deg, 30.0 ± 0 Li _x P _y S _z A _o with a diffraction peak at 3 deg (1)

  In the above eight regions, the crystal structure having a diffraction peak has extremely high lithium ion conductivity.

  Moreover, in Formula (1), A and x, y, z, and o are the same as the above.

The manufacturing method of the 2nd solid electrolyte of this invention can be manufactured by heat-processing the 1st solid electrolyte at 150-360 degreeC, for example.
The heat treatment temperature for generating the second solid electrolyte is preferably 150 to 360 ° C. Especially preferably, it is 200 to 350 degreeC.
Below 150 ° C., crystallization does not proceed because the temperature is equal to or lower than the glass transition point of the second solid electrolyte. On the other hand, when it exceeds 360 ° C., a crystal having low ion conductivity may be generated. The heat treatment time is not particularly limited as long as the crystal is generated, and may be instantaneous or long. Moreover, there is no limitation in particular also about the temperature rising pattern to baking temperature.

  The reaction time of the heat treatment is preferably 0.1 to 480 hours, more preferably 0.1 to 100 hours.

The second solid electrolyte of the present invention is preferably an incombustible inorganic solid having a decomposition voltage of at least 5 V or more. Further, while maintaining the property that the lithium ion transport number is 1, it can exhibit extremely high lithium ion conductivity of 10 ⁻³ S / cm level at room temperature. Therefore, it is extremely suitable as a material for a solid electrolyte of a lithium secondary battery. Moreover, it is a solid electrolyte excellent in heat resistance.

The second solid electrolyte of the present invention can be suitably used as a lithium secondary battery, particularly as an all-solid secondary battery, in combination with a positive electrode active material and a negative electrode active material.
As a positive electrode active material of an all-solid-state secondary battery, in the sulfide system, titanium sulfide (TiS ₂ ), molybdenum sulfide (MoS ₂ ), iron sulfide (FeS, FeS ₂ ), copper sulfide (CuS), and nickel sulfide (Ni ₃₎ S ₂ ) and the like can be used. Preferably, TiS ₂ can be used.
In the oxide system, bismuth oxide (Bi ₂ O ₃ ), bismuth lead acid (Bi ₂ Pb ₂ O ₅ ), copper oxide (CuO), vanadium oxide (V ₆ O ₁₃ ), lithium cobalt oxide (LiCoO ₂ ) Lithium nickelate (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), and the like can be used. Preferably, lithium cobaltate can be used.
In addition to the above, niobium selenide (NbSe ₃ ) can be used.

  A carbon material can be used as the negative electrode active material of the all-solid-state secondary battery. Specifically, artificial graphite, graphite carbon fiber, resin-fired carbon, pyrolysis vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-fired carbon, polyacene, pitch-based carbon fiber, vapor-phase growth Examples include carbon fiber, natural graphite, and non-graphitizable carbon. Preferably, it is artificial graphite.

  The all-solid-state secondary battery of the present invention operates as a battery without causing side reactions even when the electrolyte and the electrode agent are contacted or mixed and exposed to high temperatures. In addition, the energy density is high, and safety, charge / discharge cycle characteristics, and long-term stability are excellent.

Hereinafter, the present invention will be described more specifically with reference to examples.
Production Example (1) Production of Lithium Sulfide (Li ₂ S) Lithium sulfide was produced according to the method of the first aspect (two-step method) of JP-A-7-330312. Specifically, N-methyl-2-pyrrolidone (NMP) 3326.4 g (33.6 mol) and lithium hydroxide 287.4 g (12 mol) were charged into a 10 liter autoclave equipped with a stirring blade, and 300 rpm, 130 The temperature was raised to ° 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. did. 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.
Li ₂ S thus purified was used in the following examples and comparative examples.

Example 1
Li ₂ S, P ₂ S ₅ (manufactured by Aldrich) and Li ₂ SiO ₄ (manufactured by Aldrich) purified in the above production examples were used as starting materials. About 10 g of a mixture obtained by adding 68 mol parts of Li ₂ S, 32 mol parts of P ₂ S _{5, and} 1 mol part of Li ₄ SiO ₄ and 100 alumina balls having a particle diameter of 10 mmΦ are put in a 500 mL alumina container. In a planetary ball mill (Fritsch: Model No. P-5), under a nitrogen atmosphere, at room temperature (25 ° C.), with a rotational speed of 290 rpm, mechanical milling treatment (energy: 18.2 kWh / kg electrolyte) ) To obtain a white-yellow powder.

Powder X-ray diffraction measurement was performed on the obtained powder (CuKα: λ = 1.5418Å). This X-ray diffraction spectrum chart is shown in FIG. From the spectrum chart, it was confirmed that the crystal peak of Li ₂ S was completely disappeared and vitrified, that is, amorphous.
In FIG. 1, the charts of Example 1-3 and Comparative Example 2 are translated in the direction of the vertical axis in order to eliminate the overlapping of the charts, and the vertical axis indicates the strength.

As a result of elemental analysis of this powder, the weight percentages of Li, P, and S were Li: 9.4, P: 19.1, S: 70.6, and others (denoted as A): 0.9. As the weight fraction of A, a value obtained by subtracting the sum of the weight fractions of Li, P and S from 100 was used.
The elemental analysis was performed from the following ICP analysis and LC analysis.
ICP analysis: A predetermined amount of sample was precisely weighed and placed in a platinum dish. A 1N aqueous nitric acid solution was added thereto, and the mixture was heated on a hot plate and completely dissolved. Li, P and Si were quantified by ICP analysis of this solution.
LC analysis: A predetermined amount of sample was placed on a quartz board and burned in air. After the combustion gas was absorbed in the weak alkaline aqueous solution, hydrogen peroxide solution was added to oxidize the sulfur oxide to obtain sulfate ions. The sulfate ion contained in the liquid was quantified by liquid chromatography analysis, and the sulfur content was quantified.

This powder was put in a sealed container and heat-treated at 300 ° C. for 2 hours. The obtained solid electrolyte was subjected to X-ray diffraction measurement (CuKα: λ = 1.5418 mm). As shown in FIG. 5, 2θ = 17.8 ± 0.3 deg, 18.2 ± 0.3 deg, 19 Diffraction peaks at .8 ± 0.3 deg, 21.8 ± 0.3 deg, 23.8 ± 0.3 deg, 25.9 ± 0.3 deg, 29.5 ± 0.3 deg, 30.0 ± 0.3 deg. It was confirmed that it had. Moreover, when the ionic conductivity was measured by the alternating current impedance method (measurement frequency: 100 Hz to 15 MHz), it was as high as 2 × 10 ⁻³ S / cm at room temperature (25 ° C.). Here, since generation of gas was not recognized during the heat treatment, the elemental analysis result of the heat-treated product was determined to be the same as that before the heat treatment.

Example 2
Mechanical milling treatment was performed in the same manner as in Example 1 except that the amount of Li ₂ SiO ₄ added was 10 mol parts. The obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1. This X-ray diffraction spectrum chart is shown in FIG. From the spectrum chart, it was confirmed that the crystal peak of Li ₂ S almost completely disappeared and was vitrified, that is, amorphous. Further, from FIG. 2, it was confirmed that the diffraction intensity at 2θ = 27.04 ± 0.1 deg was 500 cps or less. Moreover, the weight percentage calculated | required from the result of the elemental analysis was Li: 10.7, P: 17.3, S: 63.9, others (denoted as A): 8.1. In the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, a sharp X-ray diffraction peak was observed at the same position as in Example 1. Moreover, the ionic conductivity was as high as 2 × 10 ⁻³ S / cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

Example 3
Mechanical milling treatment was performed in the same manner as in Example 1 except that the amount of Li ₂ SiO ₄ added was 18 mol parts. The obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1. This X-ray diffraction spectrum chart is shown in FIG. From the spectrum chart, it was confirmed that the crystal peak of Li ₂ S was completely disappeared and vitrified, that is, amorphous. Further, from FIG. 3, it was confirmed that the diffraction intensity at 2θ = 27.04 ± 0.1 deg was 500 cps or less. Moreover, the weight percentage calculated | required from the result of the elemental analysis was Li: 11.6, P: 16.0, S: 59.0, others (denoted as A): 13.4. In the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, a sharp X-ray diffraction peak was observed at the same position as in Example 1. Moreover, the ionic conductivity was as high as 1 × 10 ⁻³ S / cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

Comparative Example 1
Mechanical milling was performed in the same manner as in Example 1 except that Li ₄ SiO ₄ was not added in Example 1. As a result, a peak of Li ₂ S was observed in the X-ray diffraction spectrum, and it was confirmed that the reaction was not complete and the film was not amorphous. In addition, the ionic conductivity of the solid electrolyte after the heat treatment was also low.

Comparative Example 2
Mechanical milling was performed in the same manner as in Example 1 except that the amount of Li ₂ SiO ₄ added was 25 mol parts. The obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1. This X-ray diffraction spectrum chart is shown in FIG. From the spectrum chart, it was confirmed that the crystal peak of Li ₂ S was completely disappeared and vitrified, that is, amorphous. Moreover, it has also confirmed from FIG. On the other hand, the weight percentage calculated | required from the result of the elemental analysis was Li: 12.4, P: 15.0, S: 55.2, others (denoted as A): 17.4. Although a sharp X-ray diffraction peak was observed in the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, the ionic conductivity was as low as 3 × 10 ⁻⁵ S / cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

Example 4
A mechanical milling treatment was performed in the same manner as in Example 1 except that the charging ratio of Li ₂ S and P ₂ O ₅ was changed. When the obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1, no peak of Li ₂ S was observed, and it was confirmed that the powder was amorphous. On the other hand, the weight percentage calculated | required from the result of the elemental analysis was Li: 10.0, P: 18.6, S: 70.5, and others (denoted as A): 0.9. In the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, a sharp X-ray diffraction peak was observed at the same position as in Example 1, and the ionic conductivity was 3 × 10 ⁻³ S / It was as high as cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

Example 5
Mechanical milling treatment was performed in the same manner as in Example 4 except that the amount of Li ₂ SiO ₄ added was 10 mol parts. The obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1. As a result of this X-ray diffraction, no Li ₂ S peak was observed, and it was confirmed that the film was amorphous. Moreover, the weight percentage calculated | required from the result of the elemental analysis was Li: 11.2, P: 16.8, S: 63.6, others (denoted as A): 8.3. In the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, a sharp X-ray diffraction peak was observed at the same position as in Example 1. Moreover, the ionic conductivity was as high as 2 × 10 ⁻³ S / cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

Example 6
Mechanical milling treatment was performed in the same manner as in Example 4 except that the amount of Li ₂ SiO ₄ added was 18 mol parts. The obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1. As a result of this X-ray diffraction, no Li ₂ S peak was observed, and it was confirmed that the film was amorphous. Moreover, the weight percentage calculated | required from the result of the elemental analysis was Li: 12.2, P: 15.4, S: 58.6, others (denoted as A): 13.8. In the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, a sharp X-ray diffraction peak was observed at the same position as in Example 1. Moreover, the ionic conductivity was as high as 1 × 10 ⁻³ S / cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

Comparative Example 3
Mechanical milling was performed in the same manner as in Example 1 except that Li ₄ SiO ₄ was not added in Example 4. As a result, a peak of Li ₂ S was observed in the X-ray diffraction spectrum, and it was confirmed that the reaction was not complete and the film was not amorphous. In addition, the ionic conductivity of the solid electrolyte after the heat treatment was also low.

Comparative Example 4
A mechanical milling treatment was performed in the same manner as in Example 4 except that the addition amount of Li ₂ SiO ₄ was 25 mol parts. The obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1. As a result of this X-ray diffraction, no Li ₂ S peak was observed, and it was confirmed that the film was amorphous. On the other hand, the weight percentage calculated | required from the result of the elemental analysis was Li: 12.9, P: 14.4, S: 54.8, others (denoted as A): 17.8. Although a sharp X-ray diffraction peak was observed in the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, the ionic conductivity was as low as 8 × 10 ⁻⁵ S / cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

Example 7
A mechanical milling treatment was performed in the same manner as in Example 1 except that the charging ratio of Li ₂ S and P ₂ O ₅ was changed. When the obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1, no peak of Li ₂ S was observed, and it was confirmed that the powder was amorphous. On the other hand, the weight percentage calculated | required from the result of the elemental analysis was Li: 10.0, P: 17.7, S: 70.4, and others (denoted as A): 1.0. In the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, a sharp X-ray diffraction peak was observed at the same position as in Example 1, and the ionic conductivity was 2 × 10 ⁻³ S / It was as high as cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

Example 8
Mechanical milling treatment was performed in the same manner as in Example 7 except that the amount of Li ₂ SiO ₄ added was 10 mol parts. The obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1. As a result of this X-ray diffraction, no Li ₂ S peak was observed, and it was confirmed that the film was amorphous. Moreover, the weight percentage calculated | required from the result of the elemental analysis was Li: 12.2, P: 15.8, S: 63.2, others (denoted as A): 8.7. In the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, a sharp X-ray diffraction peak was observed at the same position as in Example 1. Moreover, the ionic conductivity was as high as 2 × 10 ⁻³ S / cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

Example 9
A mechanical milling treatment was performed in the same manner as in Example 7 except that the amount of Li ₂ SiO ₄ added was 18 mol parts. The obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1. As a result of this X-ray diffraction, no Li ₂ S peak was observed, and it was confirmed that the film was amorphous. Moreover, the weight percentage calculated | required from the result of the elemental analysis was Li: 13.1, P: 14.5, S: 57.9, others (denoted as A): 14.4. In the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, a sharp X-ray diffraction peak was observed at the same position as in Example 1. Moreover, the ionic conductivity was as high as 1 × 10 ⁻³ S / cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

Comparative Example 5
A mechanical milling treatment was performed in the same manner as in Example 1 except that Li ₄ SiO ₄ was not added in Example 7. As a result, a peak of Li ₂ S was observed in the X-ray diffraction spectrum, and it was confirmed that the reaction was not complete and the film was not amorphous. In addition, the ionic conductivity of the solid electrolyte after the heat treatment was also low.

Comparative Example 6
A mechanical milling treatment was performed in the same manner as in Example 7 except that the amount of Li ₂ SiO ₄ added was 25 mol parts. The obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1. As a result of this X-ray diffraction, no Li ₂ S peak was observed, and it was confirmed that the film was amorphous. On the other hand, the weight percentage calculated | required from the result of the elemental analysis was Li: 13.8, P: 13.5, S: 54.0, others (denoted as A): 18.6. Although a sharp X-ray diffraction peak was observed in the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, the ionic conductivity was as low as 3 × 10 ⁻⁵ S / cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

Example 10
Mechanical milling was performed in the same manner as in Example 4 except that Li ₃ PO ₄ was used instead of Li ₂ SiO ₃ . When the obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1, no peak of Li ₂ S was observed, and it was confirmed that the powder was amorphous. On the other hand, the weight percentage calculated | required from the result of the elemental analysis was Li: 9.9, P: 18.9, S: 70.5, and others (denoted as A): 0.6. In the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, a sharp X-ray diffraction peak was observed at the same position as in Example 1, and the ionic conductivity was 1 × 10 ⁻³ S / It was as high as cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

Example 11
A mechanical milling treatment was performed in the same manner as in Example 10 except that the amount of Li ₃ PO ₄ added was 10 mol parts. The obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1. As a result of this X-ray diffraction, no Li ₂ S peak was observed, and it was confirmed that the film was amorphous. Moreover, the weight percentage calculated | required from the result of the elemental analysis was Li: 10.7, P: 19.6, S: 63.9, others (denoted as A): 5.8. In the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, a sharp X-ray diffraction peak was observed at the same position as in Example 1. Moreover, the ionic conductivity was as high as 2 × 10 ⁻³ S / cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

Example 12
A mechanical milling treatment was performed in the same manner as in Example 10 except that the amount of Li ₃ PO ₄ added was 18 mol parts. The obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1. As a result of this X-ray diffraction, no Li ₂ S peak was observed, and it was confirmed that the film was amorphous. Moreover, the weight percentage calculated | required from the result of the elemental analysis was Li: 11.3, P: 20.2, S: 58.9, others (denoted as A): 9.6. In the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, a sharp X-ray diffraction peak was observed at the same position as in Example 1. Moreover, the ionic conductivity was as high as 1 × 10 ⁻³ S / cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

Comparative Example 7
A mechanical milling treatment was performed in the same manner as in Example 10 except that the amount of Li ₃ PO ₄ added was 25 mol parts. The obtained powder was subjected to powder X-ray diffraction measurement in the same manner as in Example 1. As a result of this X-ray diffraction, no Li ₂ S peak was observed, and it was confirmed that the film was amorphous. On the other hand, the weight percentage calculated | required from the result of the elemental analysis was Li: 11.7, P: 20.6, S: 55.2, others (it describes as A): 12.5. Although a sharp X-ray diffraction peak was observed in the solid electrolyte obtained by heat-treating this powder in the same manner as in Example 1, the ionic conductivity was as low as 5 × 10 ⁻⁵ S / cm. Here, since generation | occurrence | production of gas was not recognized during the heat processing, it was judged that the elemental analysis result of the heat processing thing was the same as the thing before heat processing.

The solid electrolyte of the present invention exhibits high lithium ion conductivity and is suitable as a material for a solid electrolyte of a lithium secondary battery.
Moreover, the manufacturing method of this invention is a low temperature area | region with a calcination temperature of 150 to 360 degreeC, and since it can manufacture a raw material in a short time, it is excellent in mass-productivity and economical efficiency.
Furthermore, the all-solid-state secondary battery using the solid electrolyte of the present invention having the above characteristics has high energy density, and is excellent in safety and charge / discharge cycle characteristics.

It is an X-ray diffraction spectrum chart of the amorphous solid electrolyte produced in Example 1-3 and Comparative Example 2. 3 is an X-ray diffraction spectrum chart of the solid electrolyte produced in Example 2. FIG. 4 is an X-ray diffraction spectrum chart of an amorphous solid electrolyte produced in Example 3. FIG. 4 is an X-ray diffraction spectrum chart of an amorphous solid electrolyte produced in Comparative Example 2. FIG. 2 is an X-ray diffraction spectrum chart of the solid electrolyte after heat treatment prepared in Example 1. FIG.

Claims (7)

It has a composition represented by the following formula (1), and in X-ray diffraction (CuKα: λ = 1.5418４), 2θ = 17.8 ± 0.3 deg, 18.2 ± 0.3 deg, 19.8 ± 0 Solid electrolyte having diffraction peaks at .3 deg, 21.8 ± 0.3 deg, 23.8 ± 0.3 deg, 25.9 ± 0.3 deg, 29.5 ± 0.3 deg, 30.0 ± 0.3 deg.
Li _x P _y S _z A _o (1)
(In the formula, A is one or more selected from Si, Ge, B, Al, and O, and A includes O.
x = 9.0 to 14.0, y = 14.0 to 21.0, z = 57.0 to 71.0, o = 0.5 to 15.0 (% by weight). ) The solid electrolyte according to claim 1 , wherein A is O. The following components (a) to (c) are reacted at the following blending ratios, have a composition represented by the following formula (1), and exhibit amorphous in X-ray diffraction (CuKα: λ = 1.5418Å). The manufacturing method of a solid electrolyte including the process of manufacturing a solid electrolyte, and the process of heat-processing the solid electrolyte which shows the said amorphous at 150-360 degreeC.
Li _x P _y S _z A _o (1)
(In the formula, A is one or more selected from Si, Ge, B, Al, and O, and A includes O.
x = 9.0 to 14.0, y = 14.0 to 21.0, z = 57.0 to 71.0, o = 0.5 to 15.0 (% by weight). )
[component]
(A) Li ₂ S
(B) P ₂ S ₅ , or elemental phosphorus and elemental sulfur (c) an inorganic element containing one or more elements selected from Si, Ge, B, Al, O and an oxygen element Compound [Combination ratio]
Component (a): Component (b) (molar ratio) = 65 to 75:35 to 25
When the total of component (a) and component (b) is 100 mol parts, component (c) is 1 to 20 mol parts The method for producing a solid electrolyte according to claim 3 , wherein the third component is one or more selected from Li ₄ SiO ₄ , Li ₃ PO ₄ , Li ₄ GeO ₄ , LiBO ₂ , and LiAlO ₃ . The manufacturing method of the solid electrolyte of Claim 3 or 4 which manufactures the solid electrolyte which shows the said amorphous by the mechanical milling method. The solid electrolyte according to claim 1 or 2, which is used for a lithium secondary battery. The all-solid-state secondary battery obtained using the solid electrolyte as described in any one of Claims 1, 2, and 6 .

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