Solid Electrolyte and Preparing Method Thereof

Abstract

A method of preparing a solid electrolyte includes preparing a mixed powder with a sulfur powder, a phosphorus powder and a lithium powder. The sulfur in the sulfur powder, the phosphorus in the phosphorus powder, and the lithium in the lithium powder are each in an elemental form. The mixed powder is milled to obtain an amorphous powder. The method includes heat-treating the amorphous powder to form a crystallized solid electrolyte.

What is claimed is: 
     
         1 . A solid electrolyte derived from a single element, comprising:
 a sulfur (S) element derived from a simple substance sulfur powder;   a phosphorus (P) element derived from a simple substance phosphorus powder; and   a lithium (Li) element derived from a simple substance lithium powder.   
     
     
         2 . The solid electrolyte of  claim 1 , wherein the solid electrolyte is Li 2x P 2y S x+5y  (0.65≤x≤0.85, 0.15≤y≤0.35). 
     
     
         3 . The solid electrolyte of  claim 1 , further comprising:
 a nickel (Ni) element derived from a simple substance nickel powder.   
     
     
         4 . The solid electrolyte of  claim 3 , wherein the solid electrolyte is Li a P b S c Ni d  (12≤a≤18, 0.8≤b≤6.4, 13.2≤c≤26, 1.2≤d≤9.6). 
     
     
         5 . The solid electrolyte of  claim 3 , further comprising:
 a chlorine (Cl) element derived from a lithium chloride(LiCl) powder.   
     
     
         6 . The solid electrolyte of  claim 5 , wherein the solid electrolyte is Li a P b S c Ni d Cl e  (12≤a≤22, 0.8≤b≤6.4, 13.2≤c≤26, 1.2≤d≤9.6, 1≤e≤4). 
     
     
         7 . A method of preparing a solid electrolyte, the method comprising:
 preparing a mixed powder comprising a sulfur powder, a phosphorus powder and a lithium powder, wherein the sulfur in the sulfur powder, the phosphorus in the phosphorus powder, and the lithium in the lithium powder are each in an elemental form;   milling the mixed powder to obtain an amorphous powder; and   heat-treating the amorphous powder to form a crystallized solid electrolyte.   
     
     
         8 . The method of  claim 7 , wherein preparing the mixed powder comprises mixing the sulfur powder, the phosphorus powder and the lithium powder according to a composition of Li 2x P 2y S x+5y  (0.65≤x≤0.85, 0.15≤y≤0.35). 
     
     
         9 . The method of  claim 7 , wherein the mixed powder consists of the sulfur powder, the phosphorus powder, and the lithium powder. 
     
     
         10 . The method of  claim 7 , wherein the amorphous powder is obtained by milling the mixed powder under conditions of 300 RPM to 1000 RPM and 4 hrs to 40 hrs by using a planetary mill. 
     
     
         11 . The method of  claim 7 , wherein the milling comprises:
 forming a slurry by mixing a 1 wt % to 50 wt % of the mixed powder with 50 wt % to 99 wt % of a solvent and then wet milling the slurry to obtain the amorphous powder, wherein heat-treating the amorphous powder comprises heat-treating the wet milled slurry.   
     
     
         12 . The method of  claim 11 , wherein the solvent is at least one selected from a group consisting of:
 at least one hydrocarbon-based solvent of pentane, hexane, 2-ethyl hexane, heptane, octane, cyclohexane, and methyl cyclohexane;   at least one BTX-based solvent of benzene, toluene, xylene, and ethylbenzene;   at least one ether-based solvent of diethyl ether, tetrahydrofuran, and 1,4-dioxane;   at least one ester-based solvent of ethyl propionate, and propyl propionate; or a mixture thereof.   
     
     
         13 . The method of  claim 7 , wherein the milling comprises dry milling. 
     
     
         14 . The method of  claim 7 , wherein the heat-treating comprises heat-treating the amorphous powder at 200° C. to 500° C. and 1 min to 100 hrs. 
     
     
         15 . The method of  claim 7 , wherein the preparing, the milling, and the heat-treating are performed in a dry room. 
     
     
         16 . The method of  claim 7 , wherein the preparing comprises:
 mixing a nickel powder and a lithium chloride powder with the mixed powder, wherein the sulfur powder, the phosphorus powder, the lithium powder, the nickel powder, the lithium chloride powder are mixed according to a composition of Li a P b S c Ni d Cl e  (12≤a≤22, 0.8≤b≤6.4, 13.2≤c≤26, 1.2≤d≤9.6, 1≤e≤4), and the nickel in the nickel powder and the chloride in the lithium chloride powder are each in an elemental form.   
     
     
         17 . An all solid-state battery comprising:
 a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode,   wherein at least one of the positive electrode, the negative electrode, and the solid electrolyte layer includes the solid electrolyte of  claim 1 .   
     
     
         18 . A method of preparing a solid electrolyte, the method comprising:
 preparing a mixed powder comprising a sulfur powder, a phosphorus powder and a lithium powder, wherein the sulfur in the sulfur powder, the phosphorus in the phosphorus powder, and the lithium in the lithium powder are each in an elemental form;   adding the mixed powder in to a solvent;   wet milling the mixed powder in the solvent, wherein the wet milling amorphizes the mixed powder in the solvent; and   heat-treating the amorphized mixed powder in the solvent, wherein the heat-treating removes the solvent and crystallizes the amorphized mixed powder to form the solid electrolyte.   
     
     
         19 . The method of  claim 18 , wherein preparing the mixed powder comprises mixing the sulfur powder, the phosphorus powder and the lithium powder according to a composition of Li 2x P 2y S x+5y  (0.65≤x≤0.85, 0.15≤y≤0.35). 
     
     
         20 . The method of  claim 18 , wherein the mixed powder consists of the sulfur powder, the phosphorus powder, and the lithium powder. 
     
     
         21 . The method of  claim 18 , wherein the wet milling comprises milling the mixed powder under conditions of 300 RPM to 1000 RPM and 4 hrs to 40 hrs by using a planetary mill. 
     
     
         22 . The method of  claim 18 , wherein adding the mixed powder in to the solvent comprises:
 mixing a 1 wt % to 50 wt % of the mixed powder with 50 wt % to 99 wt % of the solvent.   
     
     
         23 . The method of  claim 18 , wherein the solvent is a solvent selected from a group consisting of:
 a hydrocarbon-based solvent of pentane, hexane, 2-ethyl hexane, heptane, octane, cyclohexane, or methyl cyclohexane;   a BTX-based solvent of benzene, toluene, xylene, or ethylbenzene;   an ether-based solvent of diethyl ether, tetrahydrofuran, or 1,4-dioxane; and   an ester-based solvent of ethyl propionate, or propyl propionate.   
     
     
         24 . The method of  claim 18 , wherein the heat-treating comprises heat-treating at 200° C. to 500° C. and 1 min to 100 hrs. 
     
     
         25 . The method of  claim 18 , wherein the preparing, the adding, the wet milling, and the heat-treating are performed in a dry room. 
     
     
         26 . The method of  claim 18 , wherein the preparing comprises:
 mixing a nickel powder and a lithium chloride powder with the mixed powder, wherein the sulfur powder, the phosphorus powder, the lithium powder, the nickel powder, the lithium chloride powder are mixed according to a composition of Li a P b S c Ni d Cl e  (12≤a≤22, 0.8≤b≤6.4, 13.2≤c≤26, 1.2≤d≤9.6, 1≤e≤4), and the nickel in the nickel powder and the chloride in the lithium chloride powder are each in an elemental form.