Solid acid electrolytes for electrochemical devices
Improved solid acid electrolyte materials, methods of synthesizing such materials, and electrochemical devices incorporating such materials are provided. The stable electrolyte material comprises a solid acid capable undergoing rotational disorder of oxyanion groups and capable of extended operation at elevated temperatures, that is, solid acids having hydrogen bonded anion groups; a superprotonic, trigonal, tetragonal, or cubic, disordered phase; and capable of being operating at temperatures of ˜100° C. and higher.
1. A fuel cell comprising an electrolyte Membrane, wherein the electrolyte membrane comprises a solid acid of the general formula:
MH 1+x (PO 3 A) 1−x (PO 4 ) x ,
where
M is any alkali or transition metal or other functional group having a +1 charge,
A is one of either F or H, and
X is less than 1.
2. The cell as described in claim 1 , wherein M is selected from the group consisting of: Li, Na, K, Rb, Cs, Fr, and NH 4 .
3. The fuel cell as described in claim 1 , wherein the electrolyte membrane further comprises structural binder materials.
4. The fuel cell as described in claim 3 , wherein the structural binder material is a species selected from the group consisting of: graphite, polymers, ceramics, glass, and metals.
5. The fuel cell as described in claim 1 , wherein the electrolyte membrane further comprises a separate conducting material.
6. The fuel cell as described in claim 5 , wherein the conducting material is selected from the group consisting of: conducting polymer, metals and graphite.
7. The fuel cell as described in claim 1 , wherein said solid acid comprises at least one variable valence element.
8. The fuel cell as described in claim 1 , wherein said electrolyte membrane is water soluble.
9. The fuel cell as described in claim 1 , wherein said electrolyte membrane is thermally stable at temperatures above 100° C.
10. The fuel cell as described in claim 1 , wherein said electrolyte membrane conducts protons.
11. The fuel cell as described in claim 1 , wherein said electrolyte membrane has a proton conductivity of about 10 −5 Ω −1 CM −1 or higher at the temperature of utilization.
12. The fuel cell as described in claim 1 , wherein said electrolyte membrane conducts both protons and electrons.
13. The fuel cell as described in claim 2 , wherein M is Cs.
14. The fuel cell as described in claim 1 , wherein A is H.
15. The fuel cell as described in claim 1 , wherein X is 0.
16. The fuel cell as described in claim 1 , wherein the solid acid is CsH(PO 3 H).
17. The fuel cell as described in claim 1 , wherein M comprises more than one type of cation M species.
18. The fuel cell as described in claim 2 , wherein M is K.