Cathodes for metal air electrochemical cells

Abstract

A textured dual layer metal air cathode is disclosed. The cathode includes a first layer that contains 30% to 70% organic polymer by weight, a second layer that contains 10% to 30% organic polymer by weight, and a catalyst. The first layer and the second layer contact each other at a textured interface.

What is claimed is:  
     
         1 . A cathode for a metal air electrochemical cell, the cathode comprising 
 (a) a first layer including about 30% to about 70% of an organic polymer by weight;    (b) a second layer including about 10% to about 30% of an organic polymer by weight; and    (c) a catalyst,    wherein the first layer and the second layer contact each other at a textured interface.    
     
     
         2 . The cathode of  claim 1 , wherein the cathode includes from about 0.1% to about 20% of the catalyst by weight.  
     
     
         3 . The cathode of  claim 1 , wherein the first layer includes a catalyst.  
     
     
         4 . The cathode of  claim 3 , wherein the second layer includes a catalyst.  
     
     
         5 . The cathode of  claim 4 , wherein the first layer and the second layer contain different catalysts.  
     
     
         6 . The cathode of  claim 1 , wherein the catalyst is selected from the group consisting of manganese oxides, precious metals, metal heterocycles, and cobalt, and mixtures thereof.  
     
     
         7 . The cathode of  claim 6 , wherein the catalyst is manganese dioxide.  
     
     
         8 . The cathode of  claim 7 , wherein the cathode further comprises a silver catalyst.  
     
     
         9 . The cathode of  claim 1 , wherein the textured interface is coated with a catalyst.  
     
     
         10 . The cathode of  claim 9 , wherein the first layer includes a catalyst that is different from the catalyst coating the interface.  
     
     
         11 . The cathode of  claim 10 , wherein the catalyst coating the interface is selected from the group consisting of platinum and silver catalysts.  
     
     
         12 . The cathode of  claim 11 , wherein the catalyst coating the interface is a platinum catalyst.  
     
     
         13 . The cathode of  claim 12 , wherein the cathode contains less than about 3% by weight of the platinum catalyst.  
     
     
         14 . The cathode of  claim 1 , wherein the organic polymer is polytetrafluoroethylene.  
     
     
         15 . A metal air electrochemical cell comprising: 
 an anode including an anode can and an anode gel;    a cathode, the cathode including a cathode can having at least one air access port and containing a cathode structure, the anode can and cathode can being assembled to form a cell; and    a separator electronically separating the anode and the cathode positioned between the anode gel and the cathode structure;    wherein the cathode structure comprises (a) a first layer including about 30% to about 70% of an organic polymer by weight; (b) a second layer including about 10% to about 30% of an organic polymer by weight; and (c) a catalyst, wherein the first layer and the second layer contact each other at a textured interface.    
     
     
         16 . A method of making a cathode for an electrochemical cell, the method comprising combining carbon with AgMnO 4  to form a mixture, then preparing a cathode with the mixture.  
     
     
         17 . The method of  claim 16 , wherein the electrochemical cell is a metal air cell.  
     
     
         18 . The method of  claim 16 , wherein the electrochemical cell is an air-assisted alkaline cell.  
     
     
         19 . The method of  claim 16 , further comprising combining the carbon and the AgMnO 4  with PTFE to form the mixture.  
     
     
         20 . The method of  claim 16 , wherein the method comprises combining carbon with less than about 5 percent by weight AgMnO 4  to form the mixture.  
     
     
         21 . A cathode for an electrochemical cell, wherein the cathode comprises manganese and silver, and wherein the cathode is substantially free of potassium.  
     
     
         22 . The cathode of  claim 21 , wherein the cathode comprises less than about 7 percent by weight silver.  
     
     
         23 . The cathode of  claim 21 , wherein the cathode contains less than about 3 percent by weight silver.  
     
     
         24 . A cathode for a zinc air cell that has a current density of at least 70 mA/cm 2  at a voltage of −0.25 volts, versus a Hg/HgO reference.  
     
     
         25 . The cathode of  claim 24 , wherein the cathode has a current density of at least 80 mA/cm 2  at a voltage of −0.25 volts, versus a Hg/HgO reference.  
     
     
         26 . The cathode of  claim 25 , wherein the cathode has a current density of at least 90 mA/cm 2  at a voltage of −0.25 volts, versus a Hg/HgO reference.  
     
     
         27 . The cathode of  claim 26 , wherein the cathode has a current density of at least 100 mA/cm 2  at a voltage of −0.25 volts, versus a Hg/HgO reference.  
     
     
         28 . A cathode for an electrochemical cell, the cathode comprising a catalyst, wherein the cathode is prepared using AgMnO 4  as a catalyst precursor.