Suspensions for use as fuel for electrochemical fuel cells

Abstract

A fuel composition for fuel cells includes a polar solvent such as water, a first portion of a first fuel dissolved in the solvent at a saturated concentration, and a second portion of the first fuel suspended in the solvent to serve as a reservoir of fuel as the dissolved portion is consumed. Preferably, the first fuel is a hydride such as NaBH 4 . Optionally, the fuel composition also includes a second fuel such as an alcohol that also controls the solubility of the first fuel in the solvent, inhibits decomposition of the first fuel and stabilizes the suspension. Preferably, the fuel composition also includes an additive such as an alkali for stabilizing the first fuel.

What is claimed is  
     
         1 . A method of generating electricity comprising the steps of: 
 (a) providing a fuel cell including a cathode and an anode;    (b) contacting an oxidizer with said cathode; and    (c) contacting a fuel composition with said anode, said fuel composition including: 
 (i) a solvent,  
 (ii) a first portion of a fuel, dissolved in said solvent, and  
 (iii) a second portion of said fuel, suspended in said solvent.  
   
     
     
         2 . The method of  claim 1 , wherein said solvent is a polar solvent.  
     
     
         3 . The method of  claim 2 , wherein said polar solvent is water.  
     
     
         4 . The method of  claim 1 , wherein a concentration of said first portion of said fuel is at least initially substantially a saturated concentration thereof.  
     
     
         5 . The method of  claim 4 , wherein, as said first portion of said fuel is consumed, said second portion of said fuel dissolves in said solvent so as to maintain said concentration at said substantially saturated concentration.  
     
     
         6 . The method of  claim 1 , wherein said fuel is a salt, an anion whereof is a product of a reduction half-reaction, in said solvent, that has a standard reduction potential more negative than a standard reduction potential of a hydrogen electrode in said solvent.  
     
     
         7 . The method of  claim 1 , wherein said first fuel is a hydride.  
     
     
         8 . The method of  claim 1 , wherein said fuel composition further includes: 
 (iv) an additive for inhibiting decomposition of said fuel at said anode.    
     
     
         9 . The method of  claim 1 , wherein said fuel composition further includes: 
 (iv) an additive for stabilizing said first portion of said fuel in said solvent.    
     
     
         10 . The fuel composition of  claim 1 , further comprising: 
 (d) an additive for stabilizing said suspension.