Fuel cell electrolyte, membrane electrode assembly, and method of manufacturing fuel cell electrolyte

Abstract
A fuel cell electrolyte comprises: a basic polymer; an organic phosphonic acid expressed by the following general formula (1); and a hydrolyzable phosphate compound expressed by the following general formula (2):
Description

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, with reference to the accompanying drawings which are meant to be exemplary, not limiting, and wherein like elements are numbered alike in several Figures, in which:



FIG. 1 is a diagram schematically showing a TG chart for calculating water content;



FIG. 2 is a graph for showing time dependence of the water contents of Example 1 and Comparative Example 1 which were stored at 22° C. and 62% RH after acid doping, the water contents being determined by a particular water content evaluation method; and



FIG. 3 is a graph showing measurements of time dependence of open circuit voltage and cell resistance in a fuel electrode electrolyte according to Example 2 at 150° C. and in a nonhumidified state;



FIG. 4 is a graph showing the current-voltage characteristics of Example 2 and Comparative Example 2;



FIG. 5 is a graph showing the shrink characteristics obtained by TMA measurement on the fuel cell electrolytes of Example 1 and Example 3; and



FIG. 6 is a graph showing measurements of the time dependence of a cell voltage of a fuel cell using the fuel cell electrolyte of Example 1 and Example 4.


Claims
  • 1. A fuel cell electrolyte comprising: a basic polymer;an organic phosphonic acid expressed by the following general formula (1); anda hydrolyzable phosphate compound expressed by the following general formula (2):
  • 2. The fuel cell electrolyte according to claim 1, wherein the basic polymer is selected from the group consisting of polybenzimidazoles, poly(pyridines), poly(pyrimidines), polyimidazoles, polybenzothiazoles, polybenzoxazoles, polyoxadiazoles, polyquinolines, polyquinoxalines, polythiadiazoles, poly(tetrazapyrenes), polyoxazoles, polythiazoles, polyvinylpyridines, and polyvinylimidazoles.
  • 3. The fuel cell electrolyte according to claim 1, wherein the basic polymer contains poly-2,5-benzimidazole.
  • 4. The fuel cell electrolyte according to claim 1, wherein the basic polymer is cross-linked.
  • 5. The fuel cell electrolyte according to claim 1, wherein the organic phosphonic acid is selected from the group consisting of ethylphosphonic acid, methylphosphonic acid and octylphosphonic acid.
  • 6. The fuel cell electrolyte according to claim 1, wherein the organic phosphonic acid expressed by the following general formula (3):
  • 7. The fuel cell electrolyte according to claim 1, wherein the phosphate compound is selected from the group consisting of ethyl acid phosphate, methyl acid phosphate, butyl acid phosphate, oleyl acid phosphate, and dibutyl phosphate.
  • 8. The fuel cell electrolyte according to claim 1, wherein the phosphate compound is selected from the group consisting of monoethyl phosphate, monomethyl phosphate, mono-n-butyl phosphate, and mono-n-octyl phosphate.
  • 9. The fuel cell electrolyte according to claim 1, doped with 800 mol % or less of phosphoric acid with respect to the basic polymer as a reference.
  • 10. The fuel cell electrolyte according to claim 1, having a water content of 20% or less.
  • 11. The fuel cell electrolyte according to claim 1, having an expansion ratio of 20% or less.
  • 12. The membrane electrode assembly, comprising: the fuel cell electrolyte according to claim 1;an anode joined to one side of the fuel cell electrolyte; anda cathode joined to another side of the fuel cell electrolyte, whereinat least one of the anode and the cathode contains the organic phosphonic acid expressed by the general formula (1) and/or the hydrolyzable phosphate compound expressed by the general formula (2).
  • 13. The membrane electrode assembly, comprising: the fuel cell electrolyte according to claim 2;an anode joined to one side of the fuel cell electrolyte; anda cathode joined to another side of the fuel cell electrolyte, whereinat least one of the anode and the cathode contains the organic phosphonic acid expressed by the general formula (1) and/or the hydrolyzable phosphate compound expressed by the general formula (2).
  • 14. The membrane electrode assembly, comprising: the fuel cell electrolyte according to claim 5;an anode joined to one side of the fuel cell electrolyte; anda cathode joined to another side of the fuel cell electrolyte, whereinat least one of the anode and the cathode contains the organic phosphonic acid expressed by the general formula (1) and/or the hydrolyzable phosphate compound expressed by the general formula (2).
  • 15. The membrane electrode assembly according to claim 12, wherein at least one of the anode and the cathode contains the organic phosphonic acid selected from the group consisting of ethylphosphonic acid, methylphosphonic acid and octylphosphonic acid.
  • 16. The membrane electrode assembly according to claim 12, wherein at least one of the anode and the cathode contains the phosphate compound selected from the group consisting of ethyl acid phosphate, methyl acid phosphate, butyl acid phosphate, oleyl acid phosphate, and dibutyl phosphate.
  • 17. The membrane electrode assembly according to claim 12, wherein at least one of the anode and the cathode contains the phosphate compound selected from the group consisting of monoethyl phosphate, monomethyl phosphate, mono-n-butyl phosphate, and mono-n-octyl phosphate.
  • 18. The membrane electrode assembly according to claim 12, wherein the total sum of the amount of the organic phosphonic acid and hydrolyzable phosphate compound contained in the fuel cell electrolyte, the amount of the organic phosphonic acid and hydrolyzable phosphate compound contained in the anode, and the amount of the organic phosphonic acid and hydrolyzable phosphate compound contained in the cathode is in the range of 100% to 800% by mol with respect to the basic polymer.
  • 19. A method of manufacturing a fuel cell electrolyte comprising: depositing a basic polymer; andimpregnating the basic polymer with an aqueous solution in which the organic phosphonic acid expressed by the general formula (1) is dissolved.
  • 20. The fuel cell electrolyte according to claim 19, wherein the organic phosphonic acid is selected from the group consisting of ethylphosphonic acid, methylphosphonic acid and octylphosphonic acid.
Priority Claims (1)
Number Date Country Kind
2006-049340 Feb 2006 JP national