Fuel cell electrolyte membrane with basic polymer
The present invention is an electrolyte membrane comprising an acid and a basic polymer, where the acid is a low-volatile acid that is fluorinated and is either oligomeric or non-polymeric, and where the basic polymer is protonated by the acid and is stable to hydrolysis.
1. An electrolyte membrane comprising:
a fluorinated acid that contains in a range from 2 to 20 acid-functional groups per molecule and has a molecular weight of less than 10,000, wherein the fluorinated acid is selected from the group consisting of (a) perfluorinated imide acids and (b) perfluorinated sulfonic acids and perfluorinated imide acids;
a basic polymer protonated by the fluorinated acid, and comprising a polyimidazole; and
containing less than 25% by weight phosphoric acid.
2. The electrolyte membrane of claim 1 , wherein the fluorinated acid is selected from the group consisting of HO 3 S(CF 2 ) n SO 3 H, C m F 2m+1 SO 2 NHSO 2 (CF 2 ) n SO 2 NHSO 2 C m F 2m+1 , compounds there of where the (CF 2 ) n group comprises a first heteroatom, compounds thereof where the C m F 2m+1 group comprises a second heteroatom, and combinations thereof, wherein n ranges from 1-10 and m ranges from 1-8, and wherein the first heteroatom and the second heteroatom are each selected from the group consisting of oxygen and nitrogen.
3. The electrolyte membrane of claim 1 , wherein the polyimidazole is selected from the group consisting of poly[2,2′-(m-phenylene)-5,5′-bibenzimidazole], poly(2,5-benzimidazole), a polymer comprising
and combinations thereof.
4. The electrolyte membrane of claim 1 , further comprising inorganic additives.
5. The electrolyte membrane of claim 1 , further comprising a reinforcement matrix.