Electrochemical double layer capacitor

Abstract

Active electrode material, such as fibrillized blend of activated carbon, polymer, and conductive carbon, is pretreated by immersion in a sealing coating. After the active electrode material is dried, the coating seals micropores of the activated carbon or another porous material, thus preventing exposure of water molecules or other impurities trapped in the micropores to outside agents. At the same time, the sealing coating does not seal most mesapores of the porous material, allowing exposure of the mesapores' surface area to the outside agents. The pretreated active electrode material is used for making electrodes or electrode assemblies of electrical energy storage devices. For example, the electrodes may be immersed in an electrolyte to construct electrochemical double layer capacitors. Pretreatment with the sealing coating reduces the number of water molecules interacting with the electrolyte, enhancing the breakdown voltage of the capacitors.

1 . An electrochemical double layer capacitor comprising: 
 a first and a second electrode, wherein each electrode comprises an active electrode material comprising: 
 a porous material comprising a plurality of unsealed mesapores and a plurality of sealed micropores interspersed among the plurality of unsealed mesapores, at least a portion of the plurality of micropores having water molecules sealed therein;  
   a porous separator disposed between the first electrode material and the second electrode material; and    a first current collector and a second current collector, wherein the first electrode is disposed between the porous separator and the first current collector, and the second electrode is disposed between the porous separator and the second current collector.    
   
   
       2 . An electrochemical double layer capacitor according to  claim 1  wherein the plurality of sealed micropores comprises a coating sealing the plurality of sealed micropores.  
   
   
       3 . An electrochemical double layer capacitor according to  claim 2  wherein the plurality of unsealed mesapores is not sealed by the coating.  
   
   
       4 . An electrochemical double layer capacitor according to  claim 3  wherein the plurality of unsealed mesapores comprises at least a majority of mesapores of the porous material as measured by surface area.  
   
   
       5 . An electrochemical double layer capacitor according to  claim 1  wherein the porous material comprises a porous film material.  
   
   
       6 . An electrochemical double layer capacitor according to  claim 1  wherein the porous material comprises activated carbon, conductive carbon, and a binder.  
   
   
       7 . An electrochemical double layer capacitor according to  claim 10  further comprising an electrolyte in which at least a portion of the first electrode, at least a portion of the second electrode, and at least a portion of the separator are immersed.  
   
   
       8 . An electrochemical double layer capacitor according to claim  13  further comprises a container holding the first electrode, the second electrode, the separator, and the electrolyte.  
   
   
       9 . An electrochemical double layer capacitor according to  claim 1  wherein the porous material comprises a calendared porous film material.  
   
   
       10 . An electrochemical double layer capacitor according to  claim 1 , wherein the active electrode material of the first electrode, the active electrode material of the second electrode, and the porous separator are immersed in an electrolyte.  
   
   
       11 . An electrochemical double layer capacitor according to  claim 1 , wherein the porous material comprises activated carbon.  
   
   
       14 . An electrochemical double layer capacitor according to  claim 1 , wherein the porous material comprises dry carbon particles and binder particles.  
   
   
       15 . An electrochemical double layer capacitor comprising: 
 a first and a second electrode material, wherein the electrode material comprises a porous activated carbon comprising a plurality of unsealed mesapores and a plurality of sealed micropores interspersed among the plurality of unsealed mesapores, at least a portion of the plurality of micropores having water molecules sealed therein;    a porous separator disposed between the first electrode material and the second electrode material;    a first current collector and a second current collector, wherein the first electrode material is disposed between the porous separator and the first current collector, and the second electrode material is disposed between the porous separator and the second current collector;    an electrolyte, wherein the first electrode material, the second film electrode material and the porous separator are immersed in the electrolyte; and    a container, the container holding the electrolyte, the separator, and the first and second electrode material.    
   
   
       16 . An electrochemical double layer capacitor according to  claim 15  wherein the plurality of sealed micropores comprises a coating sealing the plurality of sealed micropores.  
   
   
       17 . An electrochemical double layer capacitor according to  16  wherein the plurality of unsealed mesapores is not sealed by the coating.  
   
   
       18 . An electrochemical double layer capacitor according to  claim 17  wherein the plurality of unsealed mesapores comprises at least a majority of mesapores of the porous material as measured by surface area.  
   
   
       19 . An electrochemical double layer capacitor according to  claim 15  wherein the porous material comprises a porous film material.  
   
   
       20 . An electrochemical double layer capacitor according to  claim 15 , wherein the electrode material comprises dry activated carbon particles and binder particles.