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 electro active 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.