JP2020031027A - SOLID ELECTROLYTE FOR ALL-SOLID-STATE LITHIUM-SULFUR BATTERY INCLUDING Li2S-P2S5-SeS2 SERIES GLASS CERAMIC, POSITIVE ELECTRODE MATERIAL SUITABLE FOR SOLID ELECTROLYTE, MANUFACTURING METHOD THEREOF, AND ALL-SOLID-STATE LITHIUM-SULFUR BATTERY INCLUDING THESE - Google Patents

Abstract

To provide a solid electrolyte for an all-solid-state lithium-sulfur battery which is improved from a LiS-PSglass ceramic and has improved lithium ion conductivity and stability of battery capacity after repeated charge and discharge, and a manufacturing method thereof.SOLUTION: There is provided a solid electrolyte for an all-solid lithium-sulfur battery in which, in a LiS-PSseries glass ceramic, a part of the PSis replaced by SeS, and the solid electrolyte consists of a LiS-PS-SeSseries glass ceramic whose content of SeSis 1 to 6 mol% of the content of PS. There is also provided a manufacturing method of the solid electrolyte for an all-solid lithium-sulfur battery.SELECTED DRAWING: None

Description

The present invention relates to a solid electrolyte for an all-solid lithium-sulfur battery made of a Li ₂ S—P ₂ S ₅ —SeS ₂ glass ceramic, a cathode material suitable for the solid electrolyte, a method for producing the same, and an all-solid lithium containing the same. Related to sulfur batteries.

  As the size, performance, and cost of lithium-ion batteries are required, all-solid-state lithium secondary batteries (for example, all-solid lithium-sulfur (Li-S) batteries) that use inorganic solid electrolytes are safe, It is attracting attention as a next-generation storage battery with excellent reliability and the like.

Non-Patent Document 1, a paper called "sulfide and development of all-solid-state battery using a glass-based electrolyte Future _{Perspectives", Li 2 S-P 2 S} 5 -based glass made of ceramic solid electrolyte various solid It has been reported that among electrolytes, high ion conductivity is exhibited, and that lithium ion conductivity varies depending on the composition (mixing ratio) of materials and the degree of disorder in the structure.

For example, use sulfur powder consisting of S ₈ called polysulfide positive electrode, metallic Li as a negative electrode, and the electrolyte Li 2 _{S-P 2} S ₅ based material and material obtained by mixing lithium iodide (LiI) of sulfide-based material It has been described that an all-solid lithium sulfur (Li-S) battery in which a cell was fabricated by pressurization exhibited a large discharge capacity density (see, for example, FIG. 2 of Non-Patent Document 1).

Further, Non-Patent Documents _1,2, Li 2 _S-P 2 in order to _{S 5} system increases the conductivity of the solid electrolyte made of glass-ceramic _{further, Li 2 S-P 2 S} 5 -based glass ceramic element It is disclosed that a method of substituting an element or adding an element is effective. For example, it is described that the conductivity was increased by replacing a part of P ₂ S ₅ with P ₂ S ₃ or P ₂ O ₅ , and that the conductivity was increased when LiI or GeS ₂ was added. ing. These increases in conductivity are believed to be due to sulfur deficiency, new crystal formation and improved crystallinity. The replacement with P ₂ O ₅ is also disclosed in Non-Patent Document 3.

"Development and Future Prospects of All-Solid-State Batteries Using Sulfide Glass-Based Electrolyte", Masahiro Tatsumi, Graduate School of Engineering, Osaka Prefecture University, 2014, Pulverization (57), 3-10, 2014 Structure, ionic conductivity and electrochemical stability of Li2S-P2S5-LiI glass and glass-ceramic electrolytes, Satoshi Ujiie, Akitoshi Hayashi, Masahiro Tatsumisago, Solid State Ionics 211 (2012) 42-45 `` Improved chemical stability and cyclability in Li2S-P2S5-P2O5-ZnO composite electrolytes for all-solid-state rechargeable lithium batteries '', Akitoshi Hayashi et al., Journal of Alloys and Compounds 591 (2014) 247-250

As described above, among solid electrolytes, research and development of solid electrolytes composed of Li ₂ S—P ₂ S ₅ glass ceramics are being promoted, but lithium ion conductivity and maintenance of battery capacity when charge and discharge are repeated are maintained. There is still room for improvement in this respect.

Therefore, the present invention relates to a solid electrolyte in which a Li ₂ SP ₂ S ₅ -based glass ceramic is improved, and which has improved lithium ion conductivity and stability of battery capacity when charge / discharge is repeated, and all-solid lithium sulfur. An object of the present invention is to provide a solid electrolyte for a battery and a method for producing the same. It is another object of the present invention to provide a positive electrode material for use in combination with the solid electrolyte, a method for producing the same, and an all-solid lithium-sulfur battery including the solid electrolyte.

The present inventors have result of intensive studies to achieve the above _object, the _Li 2 _S-P 2 S 5-SES ₂ system glass-ceramic having a specific composition having improved Li 2 _S-P 2 _{S 5} -based glass ceramic It has been found that the above object can be achieved when used, and the present invention has been completed.

That is, the present invention relates to the following solid electrolyte for an all-solid lithium-sulfur battery and a method for producing the same, a cathode material for use in combination with the solid electrolyte and a method for producing the same, and an all-solid lithium-sulfur battery including the solid electrolyte.
1. In a Li ₂ SP ₂ S ₅ glass ceramic,
The portion of the _P 2 _{S 5} has been substituted with a _{SeS 2, Li 2 S-P} 2 S 5 -SeS 2 based content SeS ₂ is 1-6 mol% of the content of _P 2 _{S 5} A solid electrolyte for an all-solid lithium-sulfur battery, comprising a glass ceramic.
2. The composition of the Li ₂ S—P ₂ S ₅ —SeS ₂ based glass ceramic is:
_{7Li 2 S- (3-x)} P 2 S 5 -xSeS 2
[However, x indicating the molar ratio of SeS ₂ is 0 <x ≦ 0.1. ]
Item 2. The solid electrolyte according to Item 1, wherein
3. The composition of the Li ₂ S—P ₂ S ₅ —SeS ₂ based glass ceramic is:
_{8Li 2 S- (2-x)} P 2 S 5 -xSeS 2
[However, x indicating the molar ratio of SeS ₂ is 0 <x ≦ 0.1. ]
Item 2. The solid electrolyte according to Item 1, wherein
4. Item 4. The solid electrolyte according to any one of Items 1 to 3, further comprising at least one element selected from the group consisting of Fe, Mg, Ca, V, Se and Sn.
5. The above-described item, wherein the raw material mixture containing the Li ₂ S powder, the P ₂ S ₅ powder, and the SeS ₂ powder is pulverized at room temperature using a ball mill, and the pulverized material is fired in an inert gas atmosphere. 5. The method for producing a solid electrolyte according to any one of 1 to 4.
6. An all-solid-state lithium-sulfur battery, a positive electrode material for use in combination with a solid electrolyte according to any one of claim 1 to 4, and the _{Li 2 S-P 2 S 5} -SeS 2 system glass ceramics, sulfur _{When, S-Li 2 S-P} 2 S 5 -SeS 2 -C based positive electrode material for all-solid lithium-sulfur battery, characterized by comprising a complex which is a composite of carbon.
7. After grinding at room temperature using a ball mill sulfur and carbon material, characterized in that ground under room temperature pulverized material and the _{Li 2 S-P 2 S 5} -SeS mixture of ₂ glass ceramics with a ball mill Item 7. The method for producing a positive electrode material according to Item 6 above.
8. An all-solid lithium-sulfur battery comprising a positive electrode material, a negative electrode material, and the solid electrolyte according to any one of the above items 1 to 4.

The solid electrolyte for an all-solid-state lithium-sulfur battery of the present invention is made of a Li ₂ S—P ₂ S ₅ —SeS ₂ system glass ceramic having a specific composition, and has a higher lithium content than a conventional Li ₂ S—P ₂ S ₅ system glass ceramic. The ionic conductivity is improved. Further, the all-solid-state lithium-sulfur battery provided with the solid electrolyte has improved stability in battery capacity when charging and discharging are repeated. In addition, the method for producing a solid electrolyte and a positive electrode material of the present invention is useful as a method for producing the solid electrolyte and a positive electrode material used in combination with the solid electrolyte, respectively.

FIG. 4 is a diagram showing the results (X-ray diffraction pattern of glass ceramic) of Test Example 1. It is a figure which shows the result (ion conductivity of glass ceramics) of Test Example 2. It is a figure showing the result (impedance plot of glass ceramics) of example 3 of an examination. It is a figure showing the result (DC current curve of glass ceramics) of example 4 of an examination. FIG. 9 is a view showing the results of Test Example 5 (charge / discharge characteristics 1 of an all-solid lithium-sulfur battery). FIG. 9 is a diagram showing the results of Test Example 6 (charge / discharge characteristics 2 of an all-solid lithium-sulfur battery). FIG. 2 is a schematic cross-sectional view showing an example of the arrangement of a positive electrode material 1, a solid electrolyte 2, a negative electrode material 3, and a stainless steel disk 4 in an all-solid lithium sulfur battery.

Solid electrolyte for all-solid lithium sulfur (Li-S) batteries (solid electrolyte)
The solid electrolyte for an all-solid lithium-sulfur battery of the present invention (hereinafter, also referred to as “the solid electrolyte of the present invention”) is a Li ₂ S—P ₂ S ₅ based glass ceramic, in which a part of P ₂ S ₅ is SeS _2. is substituted in, characterized by comprising the _{Li 2 S-P 2 S 5} -SeS 2 based glass ceramic content SeS ₂ is 1-6 mol% of the content of _P 2 _{S 5.}

The solid electrolyte of the present invention having the above characteristics is made of a Li ₂ S—P ₂ S ₅ —SeS ₂ system glass ceramic having a specific composition, and has a higher lithium ion concentration than a conventional Li ₂ S—P ₂ S ₅ system glass ceramic. The conductivity has improved. Further, the all-solid-state lithium-sulfur battery provided with the solid electrolyte has improved stability in battery capacity when charging and discharging are repeated.

The solid electrolyte of the present _invention, Li in 2 _S-P 2 _{S 5} based glass ceramics, wherein _P 2 part of _{S 5} is in been _Li 2 _S-P 2 S 5-SES ₂ based glass ceramics substituted SeS ₂ Therefore, the content of SeS ₂ may be 1 to 6 mol% of the content of P ₂ S ₅ , but among them, 1 to 5.3 mol% is preferable, and 3 to 3.5 mol% is more preferable. .

The solid electrolyte of the present invention, among the above, especially the composition of the glass ceramic,
_{7Li 2 S- (3-x)} P 2 S 5 -xSeS 2
[However, x indicating the molar ratio of SeS ₂ is 0 <x ≦ 0.1. ]
Is preferred. X indicating the content (mol%) of SeS ₂ with respect to the content of P ₂ S ₅ may be 0 <x ≦ 0.1, and among them, 0.03 ≦ x ≦ 0.1 is preferable, and 0 is particularly preferable. 0.08 ≦ x ≦ 0.1 is preferred.

Further, as another aspect, particularly the composition of the glass ceramic,
_{8Li 2 S- (2-x)} P 2 S 5 -xSeS 2
[However, x indicating the molar ratio of SeS ₂ is 0 <x ≦ 0.1. ]
Is preferred. X indicating the content (mol%) of SeS ₂ with respect to the content of P ₂ S ₅ may be 0 <x ≦ 0.1, and among them, 0.03 ≦ x ≦ 0.1 is preferable, and 0 is particularly preferable. 0.08 ≦ x ≦ 0.1 is preferred.

The solid electrolyte of the present invention preferably further contains at least one element selected from the group consisting of Fe, Mg, Ca, V, Se and Sn. By containing these elements, the effect of increasing the conductivity of the solid electrolyte is easily obtained. The content of these elements is not limited, but the content (mol%) of these elements with respect to the content of P ₂ S ₅ is preferably 0.03 to 0.3 mol%, and 0.08 to 0.3 mol%. 0.1 mol% is more preferred. These elements are contained by, for example, substituting a part of P ₂ S ₅ with at least one (additive) such as FeCl ₂ , FeCl ₃ , MgS, CaS, V ₂ S ₃ , SeCl ₂ , and SnCl _2. Can be.
(Method of manufacturing solid electrolyte)
Although the method for producing the solid electrolyte of the present invention is not limited, a raw material mixture containing Li ₂ S powder, P ₂ S ₅ powder, and SeS ₂ powder (and further containing the above additives, if necessary) is prepared using a ball mill. After pulverizing at room temperature, the pulverized product can be suitably manufactured by firing in an inert gas atmosphere. The content of the powder of each component in the raw material mixture is not limited, and each component may be blended so as to have a composition of the glass ceramic constituting the solid electrolyte of the present invention.

  When the raw material mixture is pulverized, it may be pulverized using a ball mill at room temperature. For example, pulverization is preferably performed using a high-speed planetary ball mill for 10 to 60 hours, more preferably 25 to 35 hours. The pulverized material may be fired in an inert gas atmosphere to obtain a desired glass ceramic, and is preferably fired at 230 to 280 ° C under an argon gas atmosphere, and more preferably fired at 255 to 265 ° C. More preferred. The firing time can be appropriately adjusted depending on the firing temperature, but is preferably 1 to 4 hours, more preferably 2 to 3 hours.

All-solid lithium-sulfur (Li-S) battery The solid electrolyte of the present invention is useful as a solid electrolyte for an all-solid lithium-sulfur (Li-S) battery, and the solid electrolyte is combined with a positive electrode material and a negative electrode material. Thereby, an all solid lithium sulfur battery can be configured.

(Positive electrode material)
As the cathode material is not limited, a known positive electrode materials in all-solid lithium sulfur battery _{(e.g., S-Li 2 S-P} 2 S 5 -C complex) can be used, in the present invention, the solid and _{Li 2 S-P 2 S 5} -SeS 2 based glass ceramics as a positive electrode material for use in combination with the electrolyte, and sulfur, which is a composite of _{carbon, S-Li 2 S-P} 2 S 5 -SeS 2 A cathode material composed of a —C-based composite is preferred.

Such cathode materials are in _{S-Li 2 S-P 2} S 5 -C complex of conventional, _S-Li 2 partially substituted into SeS ₂ of the _{P 2 S 5 S-P 2} S Any composite material represented by _5- SeS ₂ -C may be used. Among them, the content of SeS ₂ is 1 to 6 mol% of the content of P ₂ S ₅ similarly to the solid electrolyte of the present invention. Is preferred, and among them, 1 to 5.3 mol% is preferable, and 3 to 3.5 mol% is more preferable. In particular,
_{S-7Li 2 S- (3-} x) P 2 S 5 -xSeS 2 -C
[However, x indicating the molar ratio of SeS ₂ is 0 <x ≦ 0.1. ]
And
_{S-8Li 2 S- (2-} x) P 2 S 5 -xSeS 2 -C
[However, x indicating the molar ratio of SeS ₂ is 0 <x ≦ 0.1. ]
Is preferred. By using such a composite material, the stability of the battery capacity when charging and discharging of the all-solid-state lithium-sulfur battery is repeated is likely to be improved.

Method for producing the positive electrode material is not limited, after trituration at room temperature sulfur and carbon material by using a ball mill, pulverized and _{Li 2 S-P 2 S 5} -SeS mixture of ₂ glass ceramics It can be suitably manufactured by pulverizing at room temperature using a ball mill. The mixing ratio of the sulfur, the carbon material, and the Li ₂ S—P ₂ S ₅ —SeS ₂ based glass ceramic can be appropriately set so that the obtained positive electrode material has a desired composition.

  Examples of the carbon material include acetylene carbon black (AB), artificial graphite (Super P), graphite, vapor grown carbon fiber, and carbon nanotube.

When pulverizing the sulfur and carbon materials at room temperature using a ball mill, for example, it is preferable to pulverize using a high energy planetary ball mill for 5 to 15 hours, more preferably 8 to 10 hours. Further, when the ground under room temperature using a ball mill a mixture of pulverized material and _{Li 2 S-P 2 S 5} -SeS 2 based glass ceramics, for example, 5-15 hours milled using a high energy planetary ball mill It is more preferable to grind for 8 to 10 hours.

(Negative electrode material)
The negative electrode material is not limited, and a known negative electrode material for an all solid lithium sulfur battery can be used. For example, a composite material of lithium and a carbon material such as lithium metal, a lithium alloy (Li-In, Li-Al, Li-Si, etc.), a lithium-graphite intercalation compound, and the like can be given. These negative electrode materials can be used usually in the form of a metal foil.

(Example of Li-S battery)
FIG. 7 is a schematic cross-sectional view showing an example of the arrangement of the positive electrode material 1, the solid electrolyte 2, the negative electrode material 3, and the stainless steel disk 4 in the all-solid lithium sulfur battery.

  Li-S batteries can be assembled, for example, in a dry argon-filled glove box. As an example of an assembling method, first, a positive electrode material powder and a solid electrolyte powder are sequentially filled in a cell having a diameter of 8 to 12 mm, and then pressed at a pressure of 200 to 400 MPa for 1 to 5 minutes. Next, a lithium metal foil as a negative electrode material is placed on the surface of the solid electrolyte, and the three-layered pellet is sandwiched between two stainless steel disks. Next, the sandwiched pellet is pressed at 50 to 200 MPa at room temperature for 1 to 5 minutes to obtain a Li-S battery.

  Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples. However, the present invention is not limited to the embodiments.

Example 1 (Preparation of glass ceramic)
A mixture of powders of Li ₂ S, P ₂ S ₅ and SeS _{2 with} a molar ratio of 7: 2.9: 0.1 was charged in an argon-filled agate pot (capacity 45 cm ³ ) with 10 agate balls (diameter 10 mm). And mechanically pulverized and mixed at room temperature for 30 hours at a rotation speed of 510 rpm using a planetary ball mill. Next, the obtained powder was heated at 260 ° C. for 2 hours in an argon atmosphere to obtain 70Li ₂ S-29P ₂ S ₅ -1SeS ₂ glass ceramic.

Example 2 (Preparation of glass ceramic)
A mixture of powders of Li ₂ S, P ₂ S ₅ and SeS _{2 with} a molar ratio of 7: 2.95: 0.05 was charged in an argon-filled agate pot (capacity 45 cm ³ ) with 10 agate balls (diameter 10 mm). And mechanically pulverized and mixed at room temperature for 30 hours at a rotation speed of 510 rpm using a planetary ball mill. Next, the obtained powder was heated in an argon atmosphere at 260 ° C. for 2 hours to obtain 70Li ₂ S−29.5P ₂ S ₅ −0.5SeS ₂ glass ceramic.

Example 3 (Preparation of glass ceramic)
A mixture of powders of Li ₂ S, P ₂ S ₅ and SeS _{2 with} a molar ratio of 7: 2.97: 0.03 was charged to an argon-filled agate pot with 10 agate balls (diameter 10 mm) (capacity 45 cm ³ ) And mechanically pulverized and mixed at room temperature for 30 hours at a rotation speed of 510 rpm using a planetary ball mill. Next, the obtained powder was heated in an argon atmosphere at 260 ° C. for 2 hours to obtain 70Li ₂ S−29.7P ₂ S ₅ −0.3SeS ₂ glass ceramic.

Comparative Example 1 (Preparation of glass ceramic)
A mixture of powders of Li ₂ S and P ₂ S ₅ having a molar ratio of 7: 3 was placed in an argon-filled agate pot (capacity: 45 cm ³ ) having 10 agate balls (diameter: 10 mm), and a planetary ball mill was used. Then, the mixture was mechanically pulverized and mixed at a rotation speed of 510 rpm at room temperature for 30 hours. Next, the obtained powder was heated in an argon atmosphere at 260 ° C. for 2 hours to obtain 70Li ₂ S-30P ₂ S ₅ glass ceramic.

Comparative Example 2 (Preparation of glass ceramic)
A mixture of powders of Li ₂ S, P ₂ S ₅ and SeS _{2 having} a molar ratio of 7: 2.7: 0.3 was charged to an agate pot (45 cm ³ capacity) with 10 agate balls (diameter 10 mm). And mechanically pulverized and mixed at room temperature for 30 hours at a rotation speed of 510 rpm using a planetary ball mill. Next, the obtained powder was heated at 260 ° C. for 2 hours in an argon atmosphere to obtain 70Li ₂ S-27P ₂ S ₅ -3SeS ₂ glass ceramic.

Comparative Example 3 (Preparation of glass ceramic)
A mixture of powders of Li ₂ S, P ₂ S ₅ and SeS _{2 with} a molar ratio of 7: 2.5: 0.5 was charged to an agate pot (45 cm ³ capacity) with 10 agate balls (diameter 10 mm). And mechanically pulverized and mixed at room temperature for 30 hours at a rotation speed of 510 rpm using a planetary ball mill. Next, the obtained powder was heated in an argon atmosphere at 260 ° C. for 2 hours to obtain 70Li ₂ S-25P ₂ S ₅ -5SeS ₂ glass ceramic.

Example 4 (Production of all-solid Li-S battery)
To obtain a _{S-70Li 2 S-29P 2} S 5 -1SeS 2 -C composite positive electrode, first, sulfur (S) and carbon black powder (C) 3: 1 agate pot (wt.%) And mechanically pulverized and mixed at 370 rpm for 8 hours at room temperature using a planetary ball mill.

Next, the SC composite material and 70Li ₂ S-29P ₂ S ₅ -1SeS ₂ glass ceramic were mixed at a ratio of 2: 3 (wt%), mechanically pulverized at 370 rpm for 8 hours, and S-70Li ₂ A powder material for an S-29P ₂ S ₅ -1SeS ₂ -C composite positive electrode was obtained.

  In order to assemble the all-solid-state battery shown in FIG. 7, the composite positive electrode and the solid electrolyte powder were filled in a battery cell having a diameter of 12 mm, and then pressed at 380 MPa for 3 minutes. A Li foil was placed on the opposite side of the solid electrolyte as a counter electrode, and a pressure of 120 MPa was applied to obtain a solid battery.

Comparative Example 4 (Production of all-solid Li-S battery)
To obtain a _{S-70Li 2 S-30P 2} S 5 -C composite positive electrode, first, sulfur (S) and carbon black powder (C) 3: placed in an agate pot at a ratio of 1 (wt%), The mixture was mechanically pulverized and mixed at 370 rpm for 8 hours at room temperature using a planetary ball mill.

Next, the SC composite material and the Li ₂ SP ₂ S ₅ glass ceramic were mixed at a ratio of 2: 3 (wt%), and mechanically pulverized at 370 rpm for 8 hours to obtain S-70Li ₂ S-30P. It was obtained ₂ S ₅ -C composite positive electrode powder materials.

  In order to assemble the all-solid-state battery shown in FIG. 7, the composite positive electrode and the solid electrolyte powder were filled in a battery cell having a diameter of 12 mm, and then pressed at 380 MPa for 3 minutes. A Li foil was placed on the opposite side of the solid electrolyte as a counter electrode, and a pressure of 120 MPa was applied to obtain a solid battery.

Test example 1
The X-ray diffraction patterns of the glass ceramics prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were examined. FIG. 1 shows the results of X-ray diffraction spectrum measurement.

  According to the results of FIG. 1, the X-ray diffraction patterns of the glass ceramics of Examples 1 to 3 and Comparative Example 2 were almost the same as the X-ray diffraction patterns of Comparative Example 1 (standard). However, the X-ray diffraction pattern of the glass ceramic of Comparative Example 3 changed from the X-ray diffraction pattern of Comparative Example 1 (standard), indicating that the crystal structure of the glass ceramic changed.

Test example 2
The ionic conductivity of the glass ceramics prepared in Examples 1 to 5 was measured. FIG. 2 shows the measurement results.

According to the results of FIG. _{2, 7Li 2 S- (3-} x) P 2 S 5 -xSeS 2
[However, x indicating the molar ratio of SeS ₂ is 0 <x ≦ 0.1. ]
It has been found that in the solid electrolyte of the present invention represented by the following formula, the effect of improving the ionic conductivity is greatest when x = 0.1.

Test example 3
The impedance plots of the glass ceramics prepared in Example 1 and Comparative Example 1 were examined. FIG. 3 shows the measurement results.

According to the results of FIG. 3, the bulk resistance (R ₁ ) of the glass ceramic of Example 1 was smaller than the bulk resistance (R ₂ ) of the glass ceramic of Comparative Example 1. The glass-ceramic of Example 1 was found to have faster reaction kinetics, lower bulk and interface resistance, and higher ionic conductivity (5.28 × 10 ⁻³ S · cm ⁻¹ ).

Test example 4
The direct current curves of the glass ceramics prepared in Example 1 and Comparative Example 1 were examined. The applied voltage at the time of measurement was 1.0 V, the sample size was 12 φ, and the sample thickness was 0.51 mm. FIG. 4 shows the measurement results.

According to the results of FIG. 4, the ionic conductivity of the glass ceramic of Comparative Example 1 is 2.4 × 10 ⁻³ S · cm ⁻¹ , whereas the ionic conductivity of the glass ceramic of Example 1 is about 5 0.7 × 10 ⁻³ S · cm ⁻¹ . The addition of SeS ₂ greatly increased the ionic conductivity of the glass ceramic by more than twice. Further, the long-term compatibility of the glass ceramic of Example 1 with lithium metal is better than the glass ceramic of Comparative Example 1.

Test example 5
The charge and discharge characteristics of the solid state batteries of Example 4 and Comparative Example 4 were compared. The charge / discharge rate is 0.05C. FIG. 5 shows the measurement results.

Solid battery shows a single plateau at 1.8V corresponding to the conversion of sulfur to Li 2 _S. In the charging process, both solid-state batteries show a distinct potential plateau around about 2.4 V due to the oxidation reaction of Li ₂ S to sulfur. Although there was no significant difference in charge / discharge potential, the solid-state battery of Example 4 showed a smaller decrease in discharge capacity in repeated charge / discharge cycles of 5 cycles.

Test example 6
The charge and discharge characteristics of the solid state batteries of Example 4 and Comparative Example 4 were compared. The charge / discharge rate is 0.05 C, the charge potential is 1.0 to 3.0 V, and the discharge potential is 3.0 to 1.0 V. FIG. 6 shows the measurement results.

Solid state battery of Comparative Example 4 and Example 4, respectively, in the voltage range of 1.0~3.0V shows the discharge capacity of 950mAh · ^{g -1} and 1187mAh · ^{g -1.} In both cases, a decrease in capacity was observed due to repetition of charge / discharge, but the solid-state battery of Example 4 showed a smaller decrease in capacity.

  The coulomb efficiency of the solid state battery of Comparative Example 4 was about 91% in the initial cycle, whereas the coulomb efficiency of the solid state battery of Example 4 was about 92%. In addition, after 10 cycles, both showed an efficiency of about 98.5%. It can be seen that the solid state battery of Example 4 has better stability than the solid state battery of Comparative Example 4.

From the results of the above test examples, the solid electrolyte for an all-solid lithium-sulfur battery of the present invention has an improved lithium ion conductivity as compared with a solid electrolyte composed of a conventional Li ₂ S—P ₂ S ₅ based glass ceramic. In addition, it can be seen that the all-solid-state lithium-sulfur battery provided with the solid electrolyte of the present invention has improved stability in battery capacity when charging and discharging are repeated.

1. 1. Cathode material Solid electrolyte3. Negative electrode material4. Stainless steel disc

Claims (8)

In a Li ₂ SP ₂ S ₅ glass ceramic,
The portion of the _P 2 _{S 5} has been substituted with a _{SeS 2, Li 2 S-P} 2 S 5 -SeS 2 based content SeS ₂ is 1-6 mol% of the content of _P 2 _{S 5} A solid electrolyte for an all-solid lithium-sulfur battery, comprising a glass ceramic. The composition of the Li ₂ S—P ₂ S ₅ —SeS ₂ based glass ceramic is:
_{7Li 2 S- (3-x)} P 2 S 5 -xSeS 2
[However, x indicating the molar ratio of SeS ₂ is 0 <x ≦ 0.1. ]
The solid electrolyte according to claim 1, wherein The composition of the Li ₂ S—P ₂ S ₅ —SeS ₂ based glass ceramic is:
_{8Li 2 S- (2-x)} P 2 S 5 -xSeS 2
[However, x indicating the molar ratio of SeS ₂ is 0 <x ≦ 0.1. ]
The solid electrolyte according to claim 1, wherein   The solid electrolyte according to claim 1, further comprising at least one element selected from the group consisting of Fe, Mg, Ca, V, Se, and Sn. After grinding at room temperature Li 2 _S powder, a raw material mixture containing P ₂ S ₅ powder and SeS ₂ powder using a ball mill, and firing the pulverized product in an inert gas atmosphere, claim 5. The method for producing a solid electrolyte according to any one of 1 to 4. An all-solid-state lithium-sulfur battery, a positive electrode material for use in combination with a solid electrolyte according to any one of claims 1 to 4, and the _{Li 2 S-P 2 S 5} -SeS 2 system glass ceramics, sulfur _{When, S-Li 2 S-P} 2 S 5 -SeS 2 -C based positive electrode material for all-solid lithium-sulfur battery, characterized by comprising a complex which is a composite of carbon. After grinding at room temperature using a ball mill sulfur and carbon material, characterized in that ground under room temperature pulverized material and the _{Li 2 S-P 2 S 5} -SeS mixture of ₂ glass ceramics with a ball mill The method for producing a positive electrode material according to claim 6, wherein An all-solid lithium sulfur battery comprising a positive electrode material, a negative electrode material, and the solid electrolyte according to claim 1.