Encapsulated sulfur cathodes for rechargeable lithium batteries

Abstract

A battery includes an anode, a cathode, and an electrolyte disposed between the anode and the cathode. The cathode includes a hollow structure defining an internal volume and a sulfur-based material disposed within the internal volume. A characteristic dimension of the internal volume is at least 20 nm, and the sulfur-based material occupies less than 100% of the internal volume to define a void.

1 . A battery comprising:
 an anode;   a cathode; and   an electrolyte disposed between the anode and the cathode,   wherein the cathode includes a hollow structure defining an internal volume and a sulfur-based material disposed within the internal volume, a characteristic dimension of the internal volume is at least 20 nm, and the sulfur-based material occupies less than 100% of the internal volume to define a void.   
     
     
         2 . The battery of  claim 1 , wherein the characteristic dimension of the internal volume is at least 50 nm. 
     
     
         3 . The battery of  claim 1 , wherein the hollow structure includes a wall, and the wall is configured as a barrier to spatially segregate the sulfur-based material from the electrolyte. 
     
     
         4 . The battery of  claim 3 , wherein an interior of the wall is substantially devoid of the sulfur-based material. 
     
     
         5 . The battery of  claim 1 , wherein, in a substantially de-lithiated state of the sulfur-based material, a volume of the void is at least 1/3 of the internal volume. 
     
     
         6 . The battery of  claim 1 , wherein, in a substantially de-lithiated state of the sulfur-based material, a volume of the void is at least 2/3 of the internal volume. 
     
     
         7 . The battery of  claim 1 , wherein the hollow structure is a hollow, elongated structure having an aspect ratio of at least 5, and the sulfur-based material is disposed adjacent to an inner surface of the hollow, elongated structure. 
     
     
         8 . The battery of  claim 7 , wherein the hollow, elongated structure corresponds to one of a hollow, carbon fiber; a hollow, metal fiber; a hollow, metal oxide fiber; a hollow, metal nitride fiber; a hollow, metal sulfide fiber; and a hollow, composite fiber. 
     
     
         9 . The battery of  claim 1 , wherein the hollow structure is a hollow, spheroidal structure. 
     
     
         10 . The battery of  claim 9 , wherein the hollow, spheroidal structure is configured as an outer shell, and the sulfur-based material is configured as at least one nanostructure disposed within the outer shell. 
     
     
         11 . The battery of  claim 10 , wherein the sulfur-based material is configured as a hollow nanostructure, and the void is disposed within an interior of the hollow nanostructure. 
     
     
         12 . The battery of  claim 9 , wherein the hollow, spheroidal structure corresponds to one of a hollow, polymer shell; a hollow, metal shell; a hollow, metal oxide shell; a hollow, metal nitride shell; a hollow, metal sulfide shell; and a hollow, composite shell. 
     
     
         13 . The battery of  claim 1 , wherein, after 200 cycles at a rate of C/2, at least 85% of an initial discharge capacity is retained. 
     
     
         14 . The battery of  claim 1 , wherein, after 500 cycles at a rate of C/2, at least 80% of an initial discharge capacity is retained. 
     
     
         15 . A battery comprising:
 an anode;   a cathode; and   an electrolyte disposed between the anode and the cathode,   wherein the cathode includes an encapsulating structure defining an internal volume and a sulfur-based material disposed within the internal volume, the sulfur-based material occupies less than 100% of the internal volume to define a void, and a ratio of a volume of the void relative to a volume of the sulfur-based material is at least 1/5 for at least one cycling state of the sulfur-based material.   
     
     
         16 . The battery of  claim 15 , wherein, in a substantially de-lithiated state of the sulfur-based material, the ratio of the volume of the void relative to the volume of the sulfur-based material is at least 1/3. 
     
     
         17 . The battery of  claim 15 , wherein, in a substantially de-lithiated state of the sulfur-based material, the ratio of the volume of the void relative to the volume of the sulfur-based material is in the range of 1/2 to 3/1. 
     
     
         18 . The battery of  claim 15 , wherein a characteristic dimension of the internal volume is at least 20 nm. 
     
     
         19 . The battery of  claim 15 , wherein, after 30 cycles at a rate of C/2, no greater than 23% by weight of the sulfur-based material is present in the electrolyte. 
     
     
         20 . The battery of  claim 15 , wherein, after 100 cycles at a rate of C/2, no greater than 25% by weight of the sulfur-based material is present in the electrolyte.