Sulfur-carbon composite, nonaqueous electrolyte battery including electrode containing sulfur-carbon composite, and method for producing sulfur-carbon composite

Abstract

Provided are a sulfur-carbon composite having a high discharge capacity per mass and a high sulfur utilization rate, and a nonaqueous electrolyte battery including an electrode containing the sulfur-carbon composite. In the sulfur-carbon composite, a mass loss ratio X at 500° C. in thermal mass analysis and a mass ratio Y of sulfur/(sulfur+carbon) in an observation visual field at a magnification of 1000 in SEM-EDS quantitative analysis satisfy the relationship of |X/Y−1|≤0.12, and porous carbon has a mean pore diameter of 1 to 6 nm, and a specific surface area of 2000 m2g−1 or more and 3000 m2−1 or less.

1 - 9 . (canceled) 
     
     
         10 . A sulfur-carbon composite in which sulfur is carried on porous carbon, wherein
 a mass loss ratio X of the sulfur-carbon composite, in thermal mass analysis of the sulfur-carbon composite, over a temperature range from room temperature 500° C. with respect to a mass of the sulfur-carbon composite at room temperature and a mass ratio Y of sulfur/(sulfur+carbon) in an observation visual field at a magnification of 1000 in SEM-EDS quantitative analysis of the sulfur-carbon composite satisfy the relationship of:
     |X/Y− 1|≤0.12,
 
   
       the porous carbon has a mean pore diameter of 1 to 6 nm. 
     
     
         11 . The sulfur-carbon composite according to  claim 10 , the porous carbon has a specific surface area of 2000 m 2 g −1  or more and 3000 m 2 g −1  or less. 
     
     
         12 . The sulfur-carbon composite according to  claim 10 , wherein the content of sulfur in the sulfur-carbon composite is 50% by mass or more. 
     
     
         13 . An electrode comprising the sulfur-carbon composite according to  claim 10 . 
     
     
         14 . The electrode according to  claim 13 , further comprising polyethyleneimine. 
     
     
         15 . A nonaqueous electrolyte battery comprising the electrode according to  claim 13 . 
     
     
         16 . A method for producing a sulfur-carbon composite,
 the method comprising a step of heating, in a closed container, a mixture obtained by mixing sulfur with porous carbon to form a sulfur-carbon composite,   the heating step including:   a first step of heating the mixture for 5 hours or more at a temperature at which sulfur is melted; and   a second step of heating the mixture at a temperature at which sulfur is vaporized, after the first step,   wherein the porous carbon has a mean pore diameter of 1 to 6 nm.   
     
     
         17 . A method for producing a sulfur-carbon composite,
 the method comprising a step of heating, in a closed container, a mixture obtained by mixing sulfur with porous carbon to form a sulfur-carbon composite,   the heating step including heating the mixture at a temperature rise rate of 0.5° C./minute or less to a temperature at which sulfur is melted, and to a temperature at which sulfur is vaporized,   wherein the porous carbon has a mean pore diameter of 1 to 6 nm.   
     
     
         18 . The method according to  claim 17 , further comprising, prior to the step of heating, generating carbon-coated MgO, and extracting MgO from the carbon-coated MgO to obtain the porous carbon. 
     
     
         19 . The method according to  claim 18 , further comprising, prior to the step of heating, generating carbon-coated MgO, and extracting MgO from the carbon-coated MgO to obtain the porous carbon.