JP2016141574A - Method for manufacturing solid electrolyte - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide solid electrolyte glass-ceramics having an ionic conductivity higher than that of the prior art.SOLUTION: The method for manufacturing solid electrolyte glass ceramics includes heating solid electrolyte glass including Li, P, S and halogen elements at a temperature of Tor more and Tor less. When a peak top temperature on the low temperature side is Tc1 and a peak top temperature on the high temperature side is Tc2 out of exothermic peaks observed within 150°C-350°C in differential thermal analysis DTA having a temperature rising rate of 10°C/min, Tis a temperature lower by 18°C than Tc1, and Tis a temperature lower by 2°C than Tc1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a solid electrolyte glass ceramic.

There is known a method for producing a solid electrolyte glass ceramic by heating a solid electrolyte glass containing Li element, P element, S element and halogen element at a temperature equal to or higher than its crystallization temperature (Tc) (Patent Documents 1 to 3). 3 and Non-Patent Document 1).
It is known that a solid electrolyte glass ceramic containing a halogen element has high ionic conductivity.

WO2013 / 069243 Japanese Patent No. 5443445 Japanese Patent No. 5553004

Preparation and ionic conductivity of (100-x) (0.8Li2S, 0.2P2S5), xLiI glass-ceramic electronics (J Solid State Electrochem)

An object of the present invention is to provide a solid electrolyte glass ceramic having a higher ionic conductivity than conventional ones.
The present inventor obtains a solid electrolyte glass ceramic having high ion conductivity by crystallizing the raw material solid electrolyte glass at a temperature 2 to 18 ° C. lower than the crystallization temperature (Tc1) of the raw material solid electrolyte glass. I found out.
Further, the inventors have found that the halogen electrolyte-containing solid electrolyte glass ceramics have higher ionic conductivity when they have a region II type crystal structure, thereby completing the present invention.

According to the present invention, the following method for producing a solid electrolyte glass ceramic is provided.
1. A method for producing a solid electrolyte glass ceramic, comprising heating a solid electrolyte glass containing Li element, P element, S element, and halogen element at a temperature of T ₁ or more and T ₂ or less.
In the differential thermal analysis DTA with a heating rate of 10 ° C./min, T ₁ is Tc 1, the peak top temperature on the low temperature side among the exothermic peaks observed in the range of 150 ° C. to 350 ° C., and the peak top temperature on the high temperature side. the a 18 ° C. temperature lower than Tc1 when a Tc2, the _{T 2} are a 2 ℃ temperature lower than Tc1.
2. 2. The method for producing a solid electrolyte glass ceramic according to 1, wherein the solid electrolyte glass ceramic has a region II type crystal structure.

According to the present invention, it is possible to provide a solid electrolyte glass ceramic having a higher ionic conductivity than the prior art.
ADVANTAGE OF THE INVENTION According to this invention, the method of manufacturing solid electrolyte glass ceramics whose ion conductivity is still higher than a prior art can be provided.

The analysis result by the differential thermal analysis DTA of the solid electrolyte glass manufactured by the manufacture example 2, the heat processing temperature in Examples 1-4 and Comparative Examples 1-4, and the relationship of the ionic conductivity of the obtained solid electrolyte glass ceramic are shown. It is a graph.

The method for producing a solid electrolyte glass ceramic of the present invention (hereinafter referred to as the method of the present invention) heats a solid electrolyte glass containing Li element, P element, S element and halogen element at a temperature of T ₁ or more and T ₂ or less. It is characterized by that.
T ₁ is Tc 1, the peak top temperature on the low temperature side among the exothermic peaks observed in the range of 150 ° C. to 350 ° C. in the differential thermal analysis (hereinafter referred to as DTA) at a temperature increase rate of 10 ° C./min. a 18 ° C. temperature lower than Tc1 when the peak top temperature Tc2 of said _{T 2} are a 2 ℃ temperature lower than Tc1. The solid electrolyte glass is heated and crystallized at a temperature lower by 18 ° C. to 2 ° C. than Tc1 to obtain a solid electrolyte glass ceramic.

  In Patent Documents 1 to 3, a solid electrolyte glass ceramic is obtained by heat-treating a solid electrolyte glass containing Li element, P element, S element and halogen element at a temperature equal to or higher than the crystallization temperature determined by differential thermal analysis (DTA). ing.

  On the other hand, in the present invention, a solid electrolyte glass ceramic obtained by heat-treating a solid electrolyte glass containing Li element, P element, S element and halogen element at a temperature lower by 18 to 2 ° C. than its crystallization temperature is obtained by It has been found that the ionic conductivity is higher than that of the solid electrolyte glass ceramic obtained by heat treatment at a temperature equal to or higher than the crystallization temperature.

  When heated at a temperature lower than 18 ° C. below the crystallization temperature Tc1 of the solid electrolyte glass as a raw material, or when heated at a temperature within 2 ° C. below the crystallization temperature Tc1, it was heated above the crystallization temperature. The ionic conductivity may be equal to or less than the case.

  FIG. 1 shows the solid electrolyte glass obtained when the solid electrolyte glass produced in Production Example 2 having a crystallization temperature Tc1 of 209.8 ° C. is heat-treated at the temperatures shown in Examples 1 to 4 and Comparative Examples 1 to 4. Indicates the ionic conductivity of ceramics. From FIG. 1, it can be seen that solid electrolyte glass ceramics with significantly higher ionic conductivity can be obtained when heat treatment is performed in a temperature range 18 to 2 ° C. lower than the crystallization temperature of the solid electrolyte glass.

  The heating temperature in the method of the present invention is more preferably 16 to 2 ° C. lower than the crystallization temperature of the raw solid electrolyte glass, and higher ionic conductivity is 14 to 2 ° C. lower temperature range. A solid electrolyte glass ceramic having the same is obtained, and more preferable.

  The heating time in the method of the present invention is not particularly limited, but is usually 0.5 to 10 hours, preferably 1 to 5 hours, more preferably 1.5 to 4 hours.

  The heating atmosphere in the method of the present invention is not particularly limited and may be a known atmosphere, but is preferably an inert atmosphere such as a nitrogen atmosphere or under vacuum.

  The solid electrolyte glass ceramic obtained by the method of the present invention preferably has a region II type crystal structure. By having the region II type crystal structure, a solid electrolyte glass ceramic having high ion conductivity can be obtained.

Here, the region II type crystal structure is a Li ₄ GeS ₄ -Li ₃ PS ₄ system crystal having the highest ionic conductivity among Thio-LISICON crystals, Region II Li _3.25 Ge _0.25 P _0.75. It refers to a crystal structure having the same XRD pattern as S _4.

  The fact that the solid electrolyte glass ceramic has a region II type crystal structure can be confirmed by observing a peak derived from the Thio-LISICON region II type crystal structure by X-ray diffraction (CuKα: λ = 1.5418Å).

The starting material used in the method of the present invention is not particularly limited as long as it is a solid electrolyte glass (glassy solid electrolyte) containing Li element, P element, S element and halogen element as constituent components.
Examples of the halogen element include F, Cl, Br, and I. Cl, Br, or I is preferable, and Br or I is more preferable.

Among the raw material compounds for producing the solid electrolyte glass, compounds containing Li element include Li ₂ S (lithium sulfide), Li ₄ SiO ₄ (lithium orthosilicate), Li ₃ PO ₄ (lithium phosphate), Li _4. Examples include GeO ₄ (lithium germanate), LiBO ₂ (lithium metaborate), LiAlO ₃ (lithium aluminate), and Li ₂ S is preferable.
Examples of the compound containing P element include phosphorus sulfides such as P ₂ S ₃ (phosphorus trisulfide) and P ₂ S ₅ (phosphorus pentasulfide), simple phosphorus (P), Na ₃ PO ₄ (sodium phosphate), and the like. And P ₂ S ₅ is preferable.
Examples of the compound containing S element include Li ₂ S (lithium sulfide), P ₂ S ₅ (phosphorus pentasulfide), simple sulfur (S), Na ₂ S (sodium sulfide), SiS ₂ (silicon sulfide), Al ₂ S ₃ (aluminum sulfide), GeS ₂ (germanium sulfide), B ₂ S ₃ (diarsenic trisulfide), and the like, and Li ₂ S, P ₂ S ₅ , and simple sulfur (S) are preferable.
Examples of the compound containing a halogen element include LiBr, LiCl, LiI, NaBr, NaCl, and NaI, and LiBr, LiI, and LiCl are preferable.

The composition ratio of each element can be controlled by adjusting the compounding amount of the raw material compound when producing the solid electrolyte glass or the electrolyte precursor.
When the halogen compound is lithium halide, the lithium sulfide: diphosphorus pentasulfide (molar ratio) is, for example, 65:35 to 85:15, preferably 67:33 to 83:17, more preferably 67: It is 33-80: 20, Most preferably, it is 72: 28-78: 22.
In this case, the molar ratio of lithium halide to the sum of the molar amounts of lithium sulfide and diphosphorus pentasulfide is preferably 50:50 to 99: 1, more preferably 55:45 to 97: 3, Preferably it is 60: 40-96: 4, Most preferably, it is 70: 30-96: 4.

The ionic conductivity of the raw material solid electrolyte glass is preferably 3 × 10 ⁻⁴ S / cm or more, and more preferably 5 × 10 ⁻⁴ S / cm or more. More preferably, it is 7 × 10 ⁻⁴ S / cm or more.
Note that the higher the ionic conductivity of the raw material solid electrolyte glass, the higher the ionic conductivity of the obtained solid electrolyte glass ceramic, which is preferable. For example, the upper limit is 5 × 10 ⁻² S / cm. it can.

  The ionic conductivity of the solid electrolyte glass ceramic obtained by the method of the present invention is preferably 2 times or more, more preferably 3 times or more, more preferably 4 times or more of the ionic conductivity of the raw material solid electrolyte glass. More preferably it is.

The manufacturing method of the raw material solid electrolyte glass is not specifically limited, The well-known method of manufacturing solid electrolyte glass can be used.
Hereinafter, although the example of the manufacturing method of the solid electrolyte glass used as a raw material is demonstrated, the raw material used by the method of this invention is not limited to the solid electrolyte glass manufactured by these manufacturing methods.

1. First Production Method The solid electrolyte glass can be produced by reacting the raw material a and a compound containing a halogen element by a predetermined method.
(A) Raw material a
As the raw material a, Li ₂ S (lithium sulfide), P ₂ S ₃ (phosphorus trisulfide) _, P ₂ S ₅ (phosphorus pentasulfide), 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 (diarsenic trisulfide), Li ₃ PO ₄ (lithium phosphate), Li ₄ GeO ₄ (lithium germanate), LiBO ₂ (lithium metaborate), LiAlO ₃ (lithium aluminate), Na ₂ S (sodium sulfide), Na ₄ GeO ₄ (sodium germanate), Na ₄ SiO ₄ (sodium orthosilicate), Na ₃ PO ₄ (sodium phosphate), NaBO ₂ (sodium metaborate), NaAlO ₃ ( Sodium aluminate) and the like can be used. You may use these in mixture of 2 or more types.
Preferred raw materials a include a combination of Li ₂ S and P ₂ S ₅ , phosphorus sulfide, a combination of elemental sulfur and elemental phosphorus, a combination of phosphorus sulfide and elemental sulfur, a combination of phosphorus sulfide, elemental sulfur and elemental phosphorus, and the like. .
Hereinafter, the case where the raw material a is a combination of lithium sulfide and diphosphorus pentasulfide will be described.

  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.

Specifically, lithium hydroxide and hydrogen sulfide are reacted at 70 ° C. to 300 ° C. in a hydrocarbon-based organic solvent to produce lithium hydrosulfide, and then the reaction solution is dehydrosulfurized to form lithium sulfide. Can be synthesized (Japanese Patent Laid-Open No. 2010-163356).
In addition, lithium hydroxide and hydrogen sulfide are reacted at 10 ° C. to 100 ° C. in an aqueous solvent to produce lithium hydrosulfide, and then the reaction liquid is dehydrosulfurized to synthesize lithium sulfide (special feature). Application 2009-238952).

  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.

  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 long as diphosphorus pentasulfide (P ₂ S ₅ ) is industrially manufactured and sold, it can be used without particular limitation.

(B) Compound containing halogen element As the compound containing halogen element, a compound represented by the following formula (E) can be used, and one compound or a plurality of compounds may be used.
YX ... (E)

In the formula (E), Y represents an alkali metal such as lithium, sodium or potassium. Lithium and sodium are preferred, and lithium is particularly preferred.
X is the same as X in the above formula (C).
As the compound containing a halogen element, NaI, NaF, NaCl, NaBr, LiI, LiF, LiCl, or LiBr is preferable.

Moreover, as a compound containing a halogen element, the compound shown to following formula (E ') can also be used, a single compound may be used and a several compound may be used.
M _w −X _x (E ′)
In the formula (E ′), M represents Li, B, Al, Si, P, S, Ge, As, Se, Sn, Sb, Te, Pb, or Bi. P or Li is particularly preferable. w is an arbitrary integer of 1 to 2, and x is an arbitrary integer in the range of 1 to 10.
X is the same as X in the above formula (C).

As the compound containing a halogen element, _{specifically, LiF, LiCl, LiBr, LiI} , BCl 3, BBr 3, BI 3, AlF 3, AlBr 3, AlI 3, AlCl 3, SiF 4, SiCl 4, SiCl 3 _{, Si 2 Cl 6, SiBr 4} , SiBrCl 3, SiBr 2 Cl 2, SiI 4, PF 3, PF 5, PCl 3, PCl 5, POCl 3, PBr 3, POBr 3, PI 3, P 2 Cl 4, P ₂ I ₄ , SF ₂ , SF ₄ , SF ₆ , S ₂ F ₁₀ , SCl ₂ , S ₂ Cl ₂ , S ₂ Br ₂ , GeF ₄ , GeCl ₄ , GeBr ₄ , GeI ₄ , GeF ₂ , GeCl ₂ , GeBr _{2, GeI 2, AsF 3,} AsCl 3, AsBr 3, AsI 3, AsF 5, SeF 4, SeF 6, Se _{l 2, SeCl 4, Se 2} Br 2, SeBr 4, SnF 4, SnCl 4, SnBr 4, SnI 4, SnF 2, SnCl 2, SnBr 2, SnI 2, SbF 3, SbCl 3, SbBr 3, SbI 3, _{SbF 5, SbCl 5, PbF 4} , PbCl 4, PbF 2, PbCl 2, PbBr 2, PbI 2, BiF 3, BiCl 3, BiBr 3, BiI 3, TeF 4, Te 2 F 10, TeF 6, TeCl 2, Examples include TeCl ₄ , TeBr ₂ , TeBr ₄ , TeI _4, NaI, NaF, NaCl, NaBr, etc., preferably LiCl, LiBr, LiI, PCl ₅ , PCl ₃ , PBr ₅ and PBr ₃ , more preferably LiCl, LiBr, is LiI and PBr _3.

In addition to the raw material a and the halogen-containing compound, a compound (vitrification accelerator) for reducing the glass transition temperature may be added. Examples of vitrification promoters include Li ₃ PO ₄ , Li ₄ SiO ₄ , Li ₄ GeO ₄ , Li ₃ BO ₃ , Li ₃ AlO ₃ , Li ₃ CaO ₃ , Li ₃ InO _3, Na ₃ PO ₄ , Na Examples include inorganic compounds such as ₄ SiO ₄ , Na ₄ GeO ₄ , Na ₃ BO ₃ , Na ₃ AlO ₃ , Na ₃ CaO ₃ , and Na ₃ InO ₃ .

(C) Manufacturing method of solid electrolyte glass Hereinafter, the manufacturing method of the solid electrolyte glass using lithium sulfide and diphosphorus pentasulfide as the raw material a is demonstrated.
The ratio (molar ratio) of lithium sulfide to diphosphorus pentasulfide is 60:40 to 90:10, preferably 65:35 to 85:15 or 70:30 to 90:10, and more preferably 67:33 to 83:17 or 72:28 to 88:12, particularly preferably 67:33 to 80:20 or 74:26 to 86:14. More preferably, it is 70: 30-80: 20 or 75: 25-85: 15. Most preferably, the ratio (molar ratio) of lithium sulfide to diphosphorus pentasulfide is 72:28 to 78:22 or 77:23 to 83:17.

The ratio (molar ratio) of the total molar amount of lithium sulfide and the molar amount of diphosphorus pentasulfide and the compound containing a halogen element is 50:50 to 99: 1, preferably 55:45 to 95: 5. Preferably it is 60: 40-90: 10.
The ratio of the total molar amount of lithium sulfide and the molar amount of phosphorous pentasulfide and the compound containing a halogen element (molar ratio) is preferably 50:50 to 99: 1, more preferably 55:45 to 97: 3 or 70:30 to 98: 2, more preferably 60:40 to 96: 4 or 80:10 to 98: 2, particularly preferably 70:30 to 96: 4 or 80:20 to 98: 2. is there. In addition, it is preferable to heat-process, after mixing the total amount of the molar amount of lithium sulfide and the molar amount of phosphorous pentasulfide, and the compound containing a halogen element by MM treatment or the like.

  A material obtained by mixing a compound containing lithium sulfide, diphosphorus pentasulfide and a halogen element in the above-mentioned mixing ratio is melt-quenched, mechanical milling (hereinafter, “mechanical milling” is appropriately referred to as “MM”), and in an organic solvent. The solid electrolyte glass is manufactured by processing by a slurry method or a solid phase method in which the raw materials are reacted with each other.

(A) Melting and quenching method The melting and quenching method is described, for example, in JP-A-6-279049 and WO2005 / 119706. Specifically, P ₂ S ₅ , Li ₂ S and a halogen-containing compound are mixed in a predetermined amount in a mortar and pelletized, and then placed in a carbon-coated quartz tube and vacuum-sealed. After reacting at a predetermined reaction temperature, the solid electrolyte glass is obtained by putting it in ice and rapidly cooling it.

The reaction temperature is preferably 400 ° C to 1000 ° C, more preferably 800 ° C to 900 ° C.
The reaction time is preferably 0.1 hour to 12 hours, more preferably 1 to 12 hours.

  The quenching temperature of the reactant is usually 10 ° C. or less, preferably 0 ° C. or less, and the cooling rate is usually about 1 to 10,000 K / sec, preferably 10 to 10,000 K / sec.

(B) Mechanical milling method (MM method)
The MM method is described in, for example, JP-A-11-134937, JP-A-2004-348972, and JP-A-2004-348993.
Specifically, P ₂ S ₅ , Li ₂ S and a halogen-containing compound are mixed in a predetermined amount in a mortar and reacted for a predetermined time using, for example, various ball mills, etc., thereby obtaining a solid electrolyte glass. .
The MM method using the above raw materials can be reacted at room temperature. Therefore, there is an advantage that a solid electrolyte glass having a charged composition can be obtained without thermal decomposition of the raw material.
Further, the MM method has an advantage that it can be finely powdered simultaneously with the production of the solid electrolyte glass.

Various types such as a rotating ball mill, a rolling ball mill, a vibrating ball mill, and a planetary ball mill can be used for the MM method.
As conditions for the MM method, for example, when a planetary ball mill is used, the rotational speed may be set to several tens to several hundreds of revolutions / minute, and the treatment may be performed for 0.5 hours to 100 hours.
Further, as described in JP 2010-90003 A, balls of a ball mill may be used by mixing balls having different diameters.
Further, as described in JP2009-110920A or JP2009-2111950, an organic solvent may be added to the raw material to form a slurry, and this slurry may be subjected to MM treatment.
Further, as described in JP 2010-30889 A, the temperature in the mill during MM processing may be adjusted.
The raw material temperature during the MM treatment is preferably 60 ° C. or higher and 160 ° C. or lower.

(C) Slurry method The slurry method is described in WO2004 / 093099 and WO2009 / 047977.
Specifically, a solid electrolyte glass is obtained by reacting a predetermined amount of P ₂ S ₅ particles, Li ₂ S particles, and a halogen-containing compound in an organic solvent for a predetermined time.
The halogen-containing compound is preferably dissolved in an organic solvent or is a particle.

Here, as described in JP-A-2010-140893, in order to advance the reaction, the slurry containing the raw material may be reacted while being circulated between the bead mill and the reaction vessel.
Further, as described in WO2009 / 047977, when the raw material lithium sulfide is pulverized in advance, the reaction can proceed efficiently.
Further, as described in Japanese Patent Application No. 2010-270191, in order to increase the specific surface area of the raw material lithium sulfide, it is predetermined in a polar solvent (for example, methanol, diethyl carnate, acetonitrile) having a solubility parameter of 9.0 or more. You may soak for hours.

The reaction temperature is preferably 20 ° C. or higher and 80 ° C. or lower, more preferably 20 ° C. or higher and 60 ° C. or lower.
The reaction time is preferably 1 hour or longer and 16 hours or shorter, more preferably 2 hours or longer and 14 hours or shorter.

  The amount of the organic solvent is preferably such that the raw material lithium sulfide, diphosphorus pentasulfide, and the halogen-containing compound become a solution or slurry by the addition of the organic solvent. Usually, the amount of the raw material (total amount) added to 1 liter of the organic solvent is about 0.001 kg or more and 1 kg or less. Preferably they are 0.005 kg or more and 0.5 kg or less, Most preferably, they are 0.01 kg or more and 0.3 kg or less.

The organic solvent is not particularly limited, but an aprotic organic solvent is particularly preferable.
Examples of the aprotic organic solvent include aprotic apolar organic solvents (for example, hydrocarbon organic solvents), aprotic polar organic compounds (for example, amide compounds, lactam compounds, urea compounds, organic sulfur compounds, rings) A formula organophosphorus compound or the like) can be suitably used as a single solvent or as a mixed solvent.

As the hydrocarbon organic solvent, a saturated hydrocarbon, an unsaturated hydrocarbon, or an aromatic hydrocarbon can be used.
Examples of the saturated hydrocarbon include hexane, pentane, 2-ethylhexane, heptane, decane, and cyclohexane.
Examples of the unsaturated hydrocarbon include hexene, heptene, cyclohexene and the like.
Aromatic hydrocarbons include toluene, xylene, decalin, 1,2,3,4-tetrahydronaphthalene and the like.
Of these, toluene and xylene are particularly preferable.

Some solid electrolyte glass materials are soluble in the above organic solvents, such as phosphorus tribromide, and are suitable for production using a slurry method.
For example, lithium sulfide does not dissolve in an organic solvent, but phosphorus tribromide dissolves in an organic solvent. Therefore, when lithium sulfide, phosphorus pentasulfide, and phosphorus bromide are used as raw materials, all the raw materials must be dissolved in the organic solvent. Since the reactivity is higher than when not dissolved, the reaction time can be shortened and a high purity solid electrolyte glass with little unreacted residue can be obtained.

  The hydrocarbon solvent is preferably dehydrated in advance. Specifically, the water content is preferably 100 ppm by weight or less, and particularly preferably 30 ppm by weight or less.

  In addition, you may add another solvent to a hydrocarbon type solvent as needed. Specific examples include ketones such as acetone and methyl ethyl ketone, ethers such as tetrahydrofuran, alcohols such as ethanol and butanol, esters such as ethyl acetate, and halogenated hydrocarbons such as dichloromethane and chlorobenzene.

(D) Solid-phase method The solid-phase method is described in "HJ Deiseroth, et.al., Angew.Chem.Int.Ed.2008,47,755-758", for example. Specifically, a solid electrolyte glass is obtained by mixing a predetermined amount of a compound containing P ₂ S ₅ , Li ₂ S and halogen in a mortar and heating at a temperature of 100 to 900 ° C.

Manufacturing conditions such as temperature conditions, processing time, and charge for the melt quenching method, MM method, slurry method and solid phase method can be appropriately adjusted according to the equipment used.
As the method for producing the solid electrolyte glass, the MM method, the slurry method or the solid phase method is preferable. Since it can be produced at a low cost, the MM method and the slurry method are more preferable, and the slurry method is particularly preferable.

In any case of the melt quenching method, the MM method, the slurry method, and the solid phase method, the mixing order may be such that the composition of the final electrolyte precursor is within the above-described range. For example, in the case of the mechanical milling method, the raw materials Li ₂ S, P ₂ S ₅ and LiBr may be mixed and then milled; after Li ₂ S and P ₂ S ₅ are milled, LiBr is added. Further milling may be performed; after LiBr and P ₂ S ₅ are milled, Li ₂ S may be added and further milled; after Li ₂ S and LiBr are milled, P ₂ S ₅ is added and further milled. Also good. Further, the mixture was treated milled mixture of Li 2 _S and LiBr, may be performed further milling treatment after having mixed the mixture was milled and mixed with LiBr and P ₂ S _5.
In addition to the above, when two or more mixing processes are performed, two or more different methods may be combined. For example, Li ₂ S and P ₂ S ₅ may be processed by mechanical milling, LiBr may be mixed and processed by a solid phase method, and Li ₂ S and LiBr may be processed by a solid phase method and P _2. mixing those and S _5, LiBr were melt quenching process, a solid electrolyte glass may be manufactured by performing the slurry process.

2. Second Manufacturing Method The second manufacturing method is a method in which a halogen compound is further added to the solid electrolyte glass of the first manufacturing method described above and heated at a predetermined temperature and for a predetermined time.
The solid electrolyte glass and the halogen compound are preferably mixed by MM treatment or the like. Since the manufacturing method of the solid electrolyte glass, the heating time, the heating temperature, and the like of the material in which the halogen compound is added to the solid electrolyte glass are the same as those in the first manufacturing method, the description thereof is omitted.
As a halogen compound, the compound containing the same halogen element as the 1st manufacturing method mentioned above can be used.
In the second manufacturing method, the total amount of the halogen-containing compound used as the raw material of the solid electrolyte glass and the amount of the halogen compound mixed with the solid electrolyte glass is the same as that of the solid electrolyte glass in the first manufacturing method. This is the same as the amount of the compound containing a halogen element used as a raw material. The ratio of the halogen-containing compound that is a raw material of the solid electrolyte glass and the halogen compound mixed in the solid electrolyte glass is not particularly limited.

3. Third Production Method In the third production method, a solid electrolyte glass is produced by heating a compound containing the electrolyte precursor 1 and a halogen element at a predetermined temperature and for a predetermined time.
It is preferable that the electrolyte precursor 1 is a compound which does not have a peak in 75.0 ppm or more and 80.0 ppm or less (1st peak area) in ³¹ P-NMR, and satisfy | fills following formula (F).
Li _a M _b P _c S _d (F)
(In the formula (F), M, a, b, c and d are the same as the above formula (A).)

The electrolyte precursor 1 preferably has a peak in the region of 81.0 ppm or more and 85.0 ppm or less in ³¹ P-NMR.

The third production method is different from the first production method in that the electrolyte precursor 1 is produced without adding a compound containing a halogen element to the raw material of the solid electrolyte glass, and the electrolyte precursor 1 and the halogen element. It is the point which manufactures by mixing with the compound containing this and heating for a predetermined temperature and predetermined time.
That is, the first production method except that the electrolyte precursor 1 [solid electrolyte glass] is produced only from the raw material a, and the mixture of the electrolyte precursor 1 and the halogen-containing compound is heated at a predetermined temperature and for a predetermined time. It is the same. Therefore, since the raw material a, the compound containing a halogen element, the manufacturing method of the electrolyte precursor 1, and the manufacturing conditions of the solid electrolyte are the same as those of the first manufacturing method, the description thereof is omitted.

  When the raw material a of the electrolyte precursor 1 is lithium sulfide and diphosphorus pentasulfide, the ratio (molar ratio) of lithium sulfide to diphosphorus pentasulfide is 60:40 to 90:10, preferably 65:35 to 85: 15 or 70:30 to 90:10, more preferably 67:33 to 83:17 or 72:28 to 88:12, and particularly preferably 67:33 to 80:20 or 74:26 to 86: 14. More preferably, it is 70: 30-80: 20 or 75: 25-85: 15. Most preferably, it is 72:28 to 78:22, or 77:23 to 83:17.

  The ratio (molar ratio) of the electrolyte precursor 1 and the compound containing a halogen element is 50:50 to 99: 1, preferably 55:45 to 95: 5, and particularly preferably 60:40 to 90:10. In addition, it is preferable to heat-process, after mixing the electrolyte precursor 1 and the compound containing a halogen element by MM process etc.

  The ratio (molar ratio) of the electrolyte precursor 1 and the compound containing a halogen element is preferably 50:50 to 99: 1, more preferably 55:45 to 97: 3 or 70:30 to 98: 2. Preferably they are 60: 40-96: 4 or 80: 10-98: 2, Especially preferably, they are 70: 30-96: 4 or 80: 20-98: 2. In addition, it is preferable to heat-process, after mixing the electrolyte precursor 1 and the compound containing a halogen element by MM process etc.

  The solid electrolyte glass ceramic obtained by the method of the present invention has higher ionic conductivity than conventional ones, and is similar to the binder (binder), the positive electrode active material, the negative electrode active material, the conductive additive, or the production method described above. It may be used as an electrolyte-containing material by mixing with a halogen-containing compound or an organic solvent. The electrolyte-containing material can be used as a constituent material of a battery such as a positive electrode, an electrolyte layer, and a negative electrode, and a material for forming a member (layer) constituting the battery.

Production Example 1 (Production of NMP lithium sulfide)
(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, The temperature was raised to 130 ° C. at 300 rpm. 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 purity of the obtained purified lithium sulfide was calculated by potentiometric titration, it was 98.9% by weight (lithium hydroxide 0.1% by weight).

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.

Production Example 2
[Raw material molar ratio: Li ₂ S / P ₂ S ₅ /LiBr=63.75/21.25/15): MM method]
(1) Synthesis of solid electrolyte glass Li ₂ S (manufactured in Production Example 1), P ₂ S ₅ (manufactured by Thermophos), and LiBr (manufactured by Aldrich) were used as starting materials. In a glove box in a nitrogen atmosphere, 10 g of a mixture prepared by adjusting the above-described raw materials to a molar ratio of Li ₂ S: phosphorus sulfide: LiBr = 63.75: 21.25: 15 and 600 g of zirconia balls having a diameter of 10 mm as a planet A mold ball mill (manufactured by Fritsch: Model No. P-5) was put in an alumina pot (500 mL) and completely sealed. Using a planetary ball mill, mechanical milling was performed at 220 rpm for 40 hours to synthesize a solid electrolyte glass.

The obtained solid electrolyte glass was evaluated for DTA and ion conductivity (σ).
DTA was performed at 20 to 600 ° C. in a dry nitrogen atmosphere at a heating rate of 10 ° C./min. Using a differential thermal-thermogravimetric measuring apparatus (TGA / DSC1 manufactured by METTLER TOLEDO), the measurement was performed with about 20 mg of solid electrolyte glass.
FIG. 1 shows the analysis result by DTA. Of the exothermic peaks observed in the range of 150 ° C. to 350 ° C., when the low temperature side is the first peak and the high temperature side is the second peak, the temperature of each peak top (hereinafter, Tc1 and Tc2) is Tc1 = 209. It was .8 ° C. and Tc 2 = 242.7 ° C.

The obtained solid electrolyte glass was evaluated for ionic conductivity (σ).
The measuring method of ion conductivity is as follows.
The solid electrolyte was filled in a tablet molding machine, and a pressure of 22 MPa was applied to obtain a molded body. Furthermore, carbon was placed on both surfaces of the molded body as an electrode, and pressure was again applied with a tablet molding machine to produce a molded body for measuring conductivity (diameter: about 10 mm, thickness: about 1 mm). The molded body was subjected to ionic conductivity measurement by AC impedance measurement. The conductivity value was a value at 25 ° C. The ionic conductivity of the obtained solid electrolyte glass was 8.42E-04S / cm.

Example 1
[Raw material molar ratio: Li ₂ S / P ₂ S ₅ /LiBr=63.75/21.25/15): MM method-199.8 ° C. (= Tc 1-10 ° C.) heat treated glass ceramic]
0.7 g of the solid electrolyte glass synthesized in Production Example 2 was sealed in a 50 ml Schlenk flask with a Teflon stopper in a glove box in a nitrogen atmosphere. This was immersed in an oil bath set at 199.8 ° C. in advance and heat treated at the same temperature for 2 hours to synthesize a solid electrolyte glass ceramic. The obtained solid electrolyte glass ceramics were evaluated for ionic conductivity (σ) in the same manner as in Production Example 2. The results are shown in Table 1.

  As a result of X-ray diffraction (CuKα: λ = 1.5418４) of the obtained solid electrolyte glass ceramics, a peak derived from the Thio-LISICON region II crystal structure could be observed.

Example 2
[Raw material molar ratio: Li ₂ S / P ₂ S ₅ /LiBr=63.75/21.25/15): MM method—204.8 ° C. (= Tc 1-5 ° C.) Heat-treated glass ceramic]
A solid electrolyte glass ceramic was synthesized and evaluated in the same manner as in Example 1 except that the heat treatment temperature was 204.8 ° C. The results are shown in Table 1.
As a result of X-ray diffraction (CuKα: λ = 1.5418４) of the obtained solid electrolyte glass ceramics, a peak derived from the Thio-LISICON region II crystal structure could be observed.

Comparative Example 1
[Raw material molar ratio: Li ₂ S / P ₂ S ₅ /LiBr=63.75/21.25/15): MM method−209.8 ° C. (= Tc1) heat treated glass ceramic]
A solid electrolyte glass ceramic was synthesized and evaluated in the same manner as in Example 1 except that the heat treatment temperature was 209.8 ° C. The results are shown in Table 1.

Example 3
[Raw material molar ratio: Li ₂ S / P ₂ S ₅ /LiBr=63.75/21.25/15): MM method-197.8 ° C. (= Tc 1-12 ° C.) Heat-treated glass ceramic]
A solid electrolyte glass ceramic was synthesized and evaluated in the same manner as in Example 1 except that the heat treatment temperature was 197.8 ° C. The results are shown in Table 1.
As a result of X-ray diffraction (CuKα: λ = 1.5418４) of the obtained solid electrolyte glass ceramics, a peak derived from the Thio-LISICON region II crystal structure could be observed.

Example 4
[Raw material molar ratio: Li ₂ S / P ₂ S ₅ /LiBr=63.75/21.25/15): MM method-194.8 ° C. (= Tc 1-15 ° C.) Heat-treated glass ceramic]
A solid electrolyte glass ceramic was synthesized and evaluated in the same manner as in Example 1 except that the heat treatment temperature was 194.8 ° C. The results are shown in Table 1.

Comparative Example 2
[Raw material molar ratio: Li ₂ S / P ₂ S ₅ /LiBr=63.75/21.25/15): MM method—189.8 ° C. (= Tc 1-20 ° C.) heat-treated glass ceramic]
A solid electrolyte glass ceramic was synthesized and evaluated in the same manner as in Example 1 except that the heat treatment temperature was 189.8 ° C. The results are shown in Table 1.

Comparative Example 3
[Raw material molar ratio: Li ₂ S / P ₂ S ₅ /LiBr=63.75/21.25/15): MM method-179.8 ° C. (= Tc 1-30 ° C.) Heat-treated glass ceramic]
A solid electrolyte glass ceramic was synthesized and evaluated in the same manner as in Example 1 except that the heat treatment temperature was 179.8 ° C. The results are shown in Table 1.

Comparative Example 4
[Raw material molar ratio: Li ₂ S / P ₂ S ₅ /LiBr=63.75/21.25/15): MM method−219.8 ° C. (= Tc 1 + 10 ° C.) heat-treated glass ceramic]
A solid electrolyte glass ceramic was synthesized and evaluated in the same manner as in Example 1 except that the heat treatment temperature was 219.8 ° C. The results are shown in Table 1.

From Table 1 and FIG. 1, when the solid electrolyte glass was heated and crystallized at a temperature 18 to 2 ° C. lower than the crystallization temperature Tc1 of the solid electrolyte glass to produce a solid electrolyte glass ceramic, heat treatment was performed at other temperatures. It can be seen that the ionic conductivity is significantly higher than the case.

Claims (2)

A method for producing a solid electrolyte glass ceramic, comprising heating a solid electrolyte glass containing Li element, P element, S element, and halogen element at a temperature of T ₁ or more and T ₂ or less.
In the differential thermal analysis DTA with a heating rate of 10 ° C./min, T ₁ is Tc 1, the peak top temperature on the low temperature side among the exothermic peaks observed in the range of 150 ° C. to 350 ° C., and the peak top temperature on the high temperature side. the a 18 ° C. temperature lower than Tc1 when a Tc2, the _{T 2} are a 2 ℃ temperature lower than Tc1. The method for producing a solid electrolyte glass ceramic according to claim 1, wherein the solid electrolyte glass ceramic has a region II type crystal structure.

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