Sulfide solid electrolyte, method for producing sulfide solid electrolyte, electrode, and all solid state battery

Abstract

A main object of the present disclosure is to provide a sulfide solid electrolyte with which an electrode having excellent ion transport efficiency can be obtained. The present disclosure achieves the object by providing a sulfide solid electrolyte comprising: a Li element, a P element, and a S element; wherein a tetrahydrofuran is also included; and BET specific surface area is 8.3 m 2 /g or more.

What is claimed is: 
     
         1 . A sulfide solid electrolyte comprising:
 a Li element, a P element, and a S element; wherein   a tetrahydrofuran is also included; and   BET specific surface area is 8.3 m 2 /g or more.   
     
     
         2 . The sulfide solid electrolyte according to  claim 1 , wherein the BET specific surface area is 13.1 m 2 /g or more. 
     
     
         3 . The sulfide solid electrolyte according to  claim 1 , wherein when intensities obtained by a Raman spectroscopy: an intensity at a peak “a” derived from PS 4   3−  is regarded as Ia, and an intensity at a peak “b” derived from tetrahydrofuran is regarded as Ib, the ratio Ib/Ia, which is the ratio of the Ib to the Ia, satisfies 0.0055≤Ib/Ia<0.266. 
     
     
         4 . The sulfide solid electrolyte according to  claim 1 , wherein the sulfide solid electrolyte is amorphous. 
     
     
         5 . The sulfide solid electrolyte according to  claim 1 , wherein. the sulfide solid electrolyte is crystalline. 
     
     
         6 . A method for producing a sulfide solid electrolyte, the sulfide solid electrolyte according to  claim 1 , the method comprising:
 a precursor preparing step of mixing a raw material composition containing the constituent of the sulfide solid electrolyte with a tetrahydrofuran to obtain a precursor; and   a first burning step of volatilizing the tetrahydrofuran included in the precursor.   
     
     
         7 . The method for producing the sulfide solid electrolyte according to  claim 6 , wherein
 burning temperature in the first burning step is a temperature less than the crystallization temperature of the sulfide solid electrolyte, and   the sulfide solid electrolyte is amorphous.   
     
     
         8 . The method for producing the sulfide solid electrolyte according to  claim 7 , wherein burning temperature in the first burning step is 100° C. or less. 
     
     
         9 . The method for producing the sulfide solid electrolyte according to  claim 6 , the method further comprising:
 a second burning step of improving the crystallinity of the sulfide solid electrolyte after the first burning step; wherein   burning temperature in the second burning step is a temperature not less than the crystallization temperature of the sulfide solid electrolyte; and   the sulfide solid electrolyte is crystalline.   
     
     
         10 . The method for producing the sulfide solid electrolyte according to  claim 9 , wherein the burning temperature in the second burning step is 140° C. or more. 
     
     
         11 . An electrode to be used in an all solid state battery, the electrode comprising:
 an active material and a sulfide solid electrolyte; wherein   a tetrahydrofuran is also included; and   when the volume rate of the sulfide solid electrolyte inside the electrode is regarded as ε, ion conductivity of the sulfide solid electrolyte is regarded as σ SE , and ion conductivity of the electrode is regarded as σ ele , an ionic tortuosity factor obtained from ε*σ SE /σ ele  is 4.5 or less.   
     
     
         12 . An all solid state battery comprising:
 a cathode active material layer, an anode active material layer, and a solid electrolyte layer formed between the cathode active material layer and the anode active material layer, wherein   at least one of the cathode active material layer and the anode active material layer is the electrode according to  claim 11 .