Composite electrolyte with crosslinking agents

Abstract

A covalent crosslinking of ion-conducting materials via sulfonic acid groups can be applied to various low cost electrolyte membrane base materials for improved fuel cell performance metrics relative to such base material. This proposed approach is due, in part, to the observation that many aromatic and aliphatic polymer materials have significant potential as proton exchange membranes if a modification can increase their physical and chemical stabilities without sacrificing electrochemical performance or significantly increasing the material and production costs.

1 . A fuel cell, comprising: 
 an anode;    a cathode    fuel supply to the anode;    oxidant supply to the cathode;    a polymer electrolyte membrane positioned between the cathode and anode and fashioned with crosslinking agent crosslinked into an ion-conducting base material through hydroxyl and sulfonic acid condensation or though amine and sulfonic acid condensation; and    a membrane electrode assembly (MEA) with the polymer electrolyte membrane.    
     
     
         2 . A method of fabricating a polymer membrane suitable for use in an electrochemical fuel cell, comprising: 
 synthesizing a polymer material of viscous nature which contains 
 (a) crosslinked polymer chains,  
 (b) a solvent for dissolving the polymer chains, and  
 (c) any quantity of inorganic additives,  
   spreading the synthesized polymer material to form a uniform thickness layer on a substrate;    allowing the solvent to evaporate under controlled atmosphere from the synthesized polymer material to yield the polymer electrolyte membrane; and    preparing the polymer electrolyte membrane for use in a fuel cell by protonation and purification.    
     
     
         3 . A material with tailorable microstructure, comprising: 
 ion conducting base material that is sulfonated; and    a crosslinking agent that is hydroxyl terminated and is crosslinked to the sulfonated ion conducting base material via direct covalent crosslinking characterized by      HO—R 1 —OH+2(HSO 3 )—R 2 →R 2 —SO 2 —O—R 1 —O—SO 2 —R 2 +2H 2 O    where R 1  is the hydroxyl terminated crosslinking agent's main chain and R 2  is the sulfonated ion conducting base material.    
     
     
         4 . A material as in  claim 3 , wherein the ion conducting base material includes an inorganic cation exchange material  
     
     
         5 . A material as in  claim 4 , wherein the inorganic cation exchange material is selected from a group consisting of clay, zeolite, hydrous oxide, and inorganic salt.  
     
     
         6 . A material as in  claim 4 , wherein the inorganic cation exchange material further includes a silica based material and a proton conducting polymer based material.  
     
     
         7 . A material as in  claim 3 , wherein the main chain includes one or more chains selected from a group consisting of an aromatic polymer chain, an aliphatic polymer chain, organic molecules and inorganic molecules.  
     
     
         8 . A material as in  claim 3 , wherein the sulfonated ion conducting base material includes, one or more chains selected from a group consisting of an aromatic polymer chain, an aliphatic polymer chain, organic molecules and inorganic molecules.  
     
     
         9 . A material with tailorable microstructure, comprising: 
 ion conducting base material that is sulfonated; and    a crosslinking agent that is amine terminated and is crosslinked to the sulfonated ion conducting base material via direct covalent crosslinking characterized by      H 2 N—R 1 —N—H 2 +2(HSO 3 )—R 2 →R 2 —SO 2 —NH—R 1 —NH—SO 2 —R 2 +2H 2 O    where R 1  is the amine terminated crosslinking agent's main chain and R 2  is the sulfonated ion conducting base material.    
     
     
         10 . A material as in  claim 9 , wherein the ion conducting base material includes an inorganic cation exchange material  
     
     
         11 . A material as in  claim 10 , wherein the inorganic cation exchange material is selected from a group consisting of clay, zeolite, hydrous oxide, and inorganic salt.  
     
     
         12 . A material as in  claim 10 , wherein the inorganic cation exchange material further includes a silica based material and a proton conducting polymer based material.  
     
     
         13 . A material as in  claim 9 , wherein the main chain includes one or more chains selected from a group consisting of an aromatic polymer chain, an aliphatic polymer chain, organic molecules and inorganic molecules.  
     
     
         14 . A material as in  claim 9 , wherein the sulfonated ion conducting base material includes, one or more chains selected from a group consisting of an aromatic polymer chain, an aliphatic polymer chain, organic molecules and inorganic molecules.  
     
     
         15 . A material with tailorable microstructure, comprising: 
 ion conducting base material that is amine or hydroxyl terminated; and    a crosslinking agent that is sulfonic acid terminated and is crosslinked to the amine or hydroxyl terminated ion conducting base material via direct covalent crosslinking characterized by, respectively,      HO 3 S—R 3 —SO 3 H+2(HO)—R 4 →R 4 —SO 2 —O—R 3 —O—SO 2 —R 4 +2H 2 O  or  HO 3 S—R 3 —SO 3 H+2(H 2 N)—R 4 →R 4 —SO 2 —NH—R 3 —NH—SO 2 —R 4 +2H 2 O    where R 3  is the sulfonic acid terminated crosslinking agent's main and R 4  is the amine or hydroxyl terminated ion conducting base.    
     
     
         16 . A material as in  claim 15 , wherein the ion conducting base material includes an inorganic cation exchange material  
     
     
         17 . A material as in  claim 16 , wherein the inorganic cation exchange material is selected from a group consisting of clay, zeolite, hydrous oxide, and inorganic salt.  
     
     
         18 . A material as in  claim 16 , wherein the inorganic cation exchange material further includes a silica based material and a proton conducting polymer based material.  
     
     
         19 . A material as in  claim 15 , wherein the main chain includes one or more chains selected from a group consisting of an aromatic polymer chain, an aliphatic polymer chain, organic molecules and inorganic molecules.  
     
     
         20 . A material as in  claim 15 , wherein the sulfonated ion conducting base material includes, one or more chains selected from a group consisting of an aromatic polymer chain, an aliphatic polymer chain, organic molecules and inorganic molecules.