Sulfur nanosponge cathode for lithium-sulfur battery and methods of manufacture thereof

Abstract

The present invention is directed to lithium-sulfur batteries exhibiting a high capacity, high cycle life with low production cost and improved safety.

We claim: 
     
         1 . A cathode comprising a nanostructured sponge having a sulfur-covering-carbon structure prepared by a method comprising:
 functionalizing the surface of conductive carbon black particles, thereby forming hydroxyl and/or carboxyl groups on the surface of the conductive carbon black particles;   dispersing a mixture comprising sulfur particles and at least one surfactant in a matrix of the functionalized conductive carbon black particles; and   heating the dispersed sulfur particles and functionalized conductive carbon black particles for a time and to a temperature above the melting point of sulfur, whereby the sulfur forms a coating over the functionalized conductive carbon black particles to form the nanostructured sponge having the sulfur-covering-carbon structure.   
     
     
         2 . The cathode of  claim 1 , comprising sulfur-carbon clusters smaller than about 10 μm. 
     
     
         3 . A lithium battery comprising an anode, the cathode of  claim 1 , and an electrolyte. 
     
     
         4 . The lithium battery of  claim 3 , wherein the anode is selected from the group consisting of carbon, silicon, silicon/carbon composite, lithium titanate, and tin cobalt alloy. 
     
     
         5 . The lithium battery of  claim 3 , wherein the electrolyte is selected from the group consisting of electrolyte containing lithium salts and combination of linear and cyclic carbonates. 
     
     
         6 . A nanostructured sponge cathode comprising:
 a conductive carbon black matrix and sulfur, wherein the sulfur is disposed over the conductive carbon black particles to provide a sulfur-over-carbon structure.   
     
     
         7 . The nanostructured sponge cathode of  claim 6 , wherein the particle size of said conductive carbon black particles ranges from 80 nm to 800 nm. 
     
     
         8 . The nanostructured sponge cathode of  claim 6 , wherein the sulfur is substantially amorphous. 
     
     
         9 . The nanostructured sponge cathode of  claim 6 , further comprising a conductive polymer. 
     
     
         10 . The nanostructured sponge cathode of  claim 9 , wherein the conductive polymer comprises polypyrrole. 
     
     
         11 . The nanostructured sponge cathode of  claim 6 , wherein the amount of sulfur ranges from about 50 to about 70 wt. %.