Carbon Electrode for use in aqueous electrochemical devices and method of preparation

Abstract

A high tensile strength, highly conductive flexible composite sheet consisting of fibrillated PTFE polymers, performance enhancing dopants, and carbon particles useful in electrochemical devices such as flow through capacitors, capacitive deionization, electronic water purification, fuel cells, capacitors, super-capacitors and a method of preparation. The method consists of mixing the materials and calendering to the desired thickness and strength all at room temperature and leaving the material in a wet state without further drying.

1 . A method of preparing a high tensile strength highly conductive flexible composite sheet material for use as an electrode in an electrochemical device, comprising the steps of: 
 a. distributive mixing of polytetrafluoroethylene, carbon, dopants, and solvent under low shear conditions and    b. fibrillating said mixture by biaxial calendering to desired strength and thickness whereby said electrodes can be assembled directly into said device without drying.    
   
   
       2 . The method of  claim 1  wherein said carbon consists of 8 parts activated carbon to 1 part carbon black.  
   
   
       3 . The method of  claim 1  wherein said electrode consists of 9 parts total carbon to 1 part polytetrafluoroethylene.  
   
   
       4 . The method of  claim 1  wherein said dopant is chosen from one of the many alkali halides.  
   
   
       5 . The method of  claim 1  wherein distributive mixing is performed by a planetary mixer.  
   
   
       6 . The method of  claim 1  further including a means to stabilize the water content of said electrode.  
   
   
       7 . The method of  claim 1  wherein said biaxial calender has a means for rotating said electrode material and reintroducing into said biaxial calendar.  
   
   
       8 . The method of  claim 1  further including an operation to reduce the thickness of the carbon sheet.