Single component sulfur-based cathodes for lithium and lithium-ion batteries

Abstract

The present invention pertains to the selection of cathode materials. The cathode materials of concern are the conducting polymer or backbone and the redox active species or sulfur species. The selection of the materials is based on the characteristics of the materials relating to the other components of the batteries and to each other. The present invention also pertains to the resultant cathode materials, particularly a selected cathode material of a single component sulfur-based conducting polymer with the sulfur species covalently linked to the conducting polymer, and most particularly a thiophene based polymer with covalently linked sulfur species. The conducting polymers have been covalently-derivatized with sulfides and/or sulfide-containing groups as battery cathode materials. The present invention also pertains to a battery employing the selection method and resultant cathode materials.

1 ) A method of selecting cathode materials for a sulfur-based Lithium battery wherein the cathode comprises a conducting polymer and a sulfur species; 
 identifying a characteristic of the conducting polymer;    identifying a characteristic of the sulfur species;    evaluating the characteristic of the conducting polymer and the sulfur species;    selecting the conducting polymer and the sulfur species based on the identified characteristic; 
 wherein the identified characteristic of the sulfur species and the identified characteristic of the conducting polymer are at least one characteristic selected from the group consisting of: ease of fabrication using straightforward synthetic procedures;  
   ionically conductive for Li +  ions; a high density of electroactive species per weight and volume/large inherent charge capacity >230 Ah/kg; good overlap of thermodynamic potentials of the sulfur species and the conducting polymer: reasonable electronic conductivity (10 −4  S/cm) of the cathode materials; no solubility in electrolyte solutions;    or electrochemically stable to many repeated charge and discharge cycles/a capacity fade of less than 10% when the cathode material is cycled 1000 times.    
   
   
       2 ) The method of  claim 1  wherein the identified characteristics are all of the at least one characteristics.  
   
   
       3 ) The method of  claim 1  wherein the at least one characteristic is good overlap of thermodynamic potentials of the sulfur species and the conducting polymer.  
   
   
       4 ) The method of  claim 1  wherein the at least one characteristic is no solubility in electrolyte solutions.  
   
   
       5 ) A cathode material for use in a sulfur-based Lithium battery comprising a sulfur species and a conducting polymer; 
 wherein the conducting polymer and the sulfur species exhibit at least one characteristic selected from the group consisting of: ease of fabrication using straightforward synthetic procedures; ionically conductive for Li +  ions; a high density of electroactive species per weight and volume/large inherent charge capacity >230 Ah/kg; good overlap of thermodynamic potentials of the sulfur species and the conducting polymer: reasonable electronic conductivity (10 −4  S/cm) of the cathode materials: no solubility in electrolyte solutions: or electrochemically stable to many repeated charge and discharge cycles/a capacity fade of less than 10% when the cathode material is cycled 1000 times.    
   
   
       6 ) The cathode material of  claim 5 , wherein the at least one characteristic includes all of the characteristics from the group consisting of: ease of fabrication using straightforward synthetic procedures: ionically conductive for Li +  ions: a high density of electroactive species per weight and volume/large inherent charge capacity >230 Ah/kg; good overlap of thermodynamic potentials of the sulfur species and the conducting polymer: reasonable electronic conductivity (10 −4  S/cm) of the cathode materials: no solubility in electrolyte solutions: or electrochemically stable to many repeated charge and discharge cycles/a capacity fade of less than 10% when the cathode material is cycled 1000 times.  
   
   
       7 ) The cathode material of  claim 5 , wherein the at least one characteristic is good overlap of thermodynamic potentials of the sulfur species and the conducting polymer.  
   
   
       8 ) The cathode material of  claim 5 , wherein the at least one characteristic is good overlap of thermodynamic potentials of the sulfur species and the conducting polymer and no solubility in electrolyte solutions.  
   
   
       9 ) A cathode material for use in a sulfur-based Lithium battery containing an electrolyte comprising, a sulfur species and a conducting polymer wherein the conducting polymer is a single component sulfur-based conducting polymer with the sulfur species covalently linked to the conducting polymer.  
   
   
       10 ) The cathode material of  claim 9 , wherein the covalent link of the sulfur species and the conducting polymer provides suitable fade characteristics by not allowing the sulfur species to be soluble in the electrolyte.  
   
   
       11 ) The cathode material of  claim 9 , wherein the electrolyte contains no other sulfur or other sulfur species except for the linked sulfur species.  
   
   
       12 ) The cathode material of  claim 9 , wherein the cathode material is a thiophene based polymer with the covalently linked sulfur species.  
   
   
       13 ) The cathode material of  claim 9 , wherein the conducting polymer are covalently-derivatized with sulfides and/or sulfide-containing groups.  
   
   
       14 ) A cathode material for use in a sulfur-based Lithium battery containing an electrolyte comprising, a sulfur species including sulfide components and a conducting polymer wherein the conducting polymer is a single component sulfur-based conducting polymer wherein physical constraints of the conducting polymer and the sulfide components via covalent bonds which are present regardless of charge state of the cathode material.  
   
   
       15 ) An electric current producing cell comprising: 
 a) an anode;    b) a cathode containg a cathode material of  claim 14;  and,    c) an electrolyte between the anode and cathode.    
   
   
       16 ) An electric current producing cell comprising: 
 a) an anode;    b) a cathode containg a cathode material of  claim 12;  and,    c) an electrolyte between the anode and cathode.    
   
   
       17 ) An electric current producing cell comprising: 
 a) an anode;    b) a cathode containg a cathode material selected by the method of  claim 2;  and,    c) an electrolyte between the anode and cathode.    
   
   
       18 ) The cathode material of  claim 13 , wherein the sulfur-derivatized conducting polymer is represented by a formula (R i ) n (Y j A k ) m  (where R is monomer or oligomer units of the conducting polymer, i is 1 to n and n is greater than 20, Y is a functionalizing group that provides additional physical or chemical properties to the conducting polymer and j is 0 to n; A is the sulfur species, k is 1 to n and m is 1 to 12.  
   
   
       19 ) The cathode material of  claim 18 , wherein n is greater than 1000.  
   
   
       20 ) The cathode material of  claim 19 , wherein n is greater than 100,000.  
   
   
       21 ) The cathode material of  claim 13 , wherein the sulfur-derivatized conducting polymer represented by a formula (R) n (YS m ) x  (where R is a conducting polymer backbone and n is greater than 20; Y is a functionalizing group; S is an organosulfur moiety, m is 1 to 12 and x is 1 to 4.  
   
   
       22 ) The cathode material of  claim 21 , wherein n is greater than 1000.  
   
   
       23 ) The cathode material of  claim 22 , wherein n is greater than 100,000.  
   
   
       24 ) The cathode material of  claim 21 , wherein R is polythiophene or its derivatives.  
   
   
       25 ) The cathode material of  claim 24 , wherein the single component sulfur-based conducting polymer is represented by:  
     
       
         
         
             
             
         
       
     
   
   
       26 ) The cathode material of  claim 24 , wherein the single component sulfur-based conducting polymer is represented by: