GAS BARRIER FOR ELECTROCHEMICAL CELLS

1 . A membrane-electrode-assembly (MEA) for an electrochemical cell employing a gas, the MEA comprising:

a proton exchange membrane;

a first electrode disposed on one side of the membrane;

a second electrode disposed on the opposite side of the membrane; and

a metallic layer disposed between the membrane and the first electrode, the membrane and the second electrode, or both;

wherein the metallic layer has a composition and thickness suitable for reducing the amount of gas crossover at the membrane by equal to or greater than about 20% as compared to the amount of gas crossover at the membrane in the absence of the metallic layer.

2 . The MEA of claim 1 , wherein the gas comprises hydrogen.

3 . The MEA of claim 2 , wherein:

the metallic layer has a composition and thickness suitable for reducing the amount of hydrogen crossover at the membrane by equal to or greater than about 30% as compared to the amount of hydrogen crossover at the membrane in the absence of the metallic layer.

4 . The MEA of claim 2 , wherein:

the metallic layer comprises platinum, gold, or any combination comprising at least one of the foregoing.

5 . The MEA of claim 2 , wherein:

the metallic layer is semicontinuous.

6 . The MEA of claim 2 , wherein:

the metallic layer is porous.

7 . The MEA of claim 2 , wherein:

the metallic layer is pervious to hydrogen ions.

8 . The MEA of claim 2 , wherein;

the metallic layer covers equal to or greater than about 20% of the active area of the membrane.

9 . The MEA of claim 8 , wherein:

the metallic layer covers equal to or greater than about 30% of the active area of the membrane.

10 . The MEA of claim 2 , wherein:

the metallic layer is deposited on a surface of the membrane.

11 . The MEA of claim 10 , wherein:

the metallic layer is deposited on the surface of the membrane via plating, chemical reduction, or ion beam assisted deposition.

12 . The MEA of claim 2 , wherein:

the metallic layer has a thickness equal to or greater than about 1 molecule thickness.

13 . The MEA of claim 12 , wherein:

the metallic layer has a thickness equal to or greater than about 1 micro-inch.

14 . The MEA of claim 13 , wherein:

the metallic layer has a thickness equal to or greater than about 1 mil.

15 . The MEA of claim 2 , wherein:

the first electrode is disposed on the oxygen electrode side of the MEA;

the second electrode is disposed on the hydrogen electrode side of the MEA; and

the metallic layer is disposed only between the membrane and the second electrode.

16 . An electrochemical cell, comprising:

a plurality of membrane-electrode-assemblies (MEAs) alternatively arranged with a plurality of flow field members between a first cell separator plate and a second cell separator plate;

wherein at least one MEA comprises:

a proton exchange membrane;

a first electrode disposed on one side of the membrane;

a second electrode disposed on the opposite side of the membrane; and

a metallic layer disposed between the membrane and the first electrode, the membrane and the second electrode, or both;

wherein the metallic layer has a composition and thickness suitable for reducing the amount of hydrogen crossover at the membrane by equal to or greater than about 20% as compared to the amount of hydrogen crossover at the membrane in the absence of the metallic layer; and

wherein the metallic layer has a composition and thickness suitable for operating the electrochemical cell at an operating pressure difference across the at least one MEA of equal to or greater than about 50 pounds-per-square-inch (psi).

17 . The electrochemical cell of claim 16 , wherein:

the metallic layer comprises a semicontinuous or porous layer suitable for reducing the amount of hydrogen crossover at the membrane by equal to or greater than about 30% as compared to the amount of hydrogen crossover at the membrane in the absence of the metallic layer.

18 . The electrochemical cell of claim 16 , wherein:

the metallic layer comprises a semicontinuous or porous layer of platinum, gold, or any combination comprising at least one of the foregoing.

19 . An electrolysis cell, comprising:

a plurality of membrane-electrode-assemblies (MEAs) alternatively arranged with a plurality of flow field members between a first cell separator plate and a second cell separator plate;

wherein at least one MEA comprises:

a proton exchange membrane;

a first electrode disposed on one side of the membrane;

a second electrode disposed on the opposite side of the membrane; and

a metallic layer disposed between the membrane and the first electrode, the membrane and the second electrode, or both;

wherein the metallic layer has a composition and thickness suitable for reducing the amount of hydrogen crossover at the membrane by equal to or greater than about 20% as compared to the amount of hydrogen crossover at the membrane in the absence of the metallic layer; and

wherein the metallic layer has a composition and thickness suitable for operating the electrochemical cell at an operating pressure difference across the at least one MEA of equal to or greater than about 100 pounds-per-square-inch (psi).

20 . The electrochemical cell of claim 19 , wherein:

the metallic layer comprises a semicontinuous or porous layer suitable for reducing the amount of hydrogen crossover at the membrane by equal to or greater than about 30% as compared to the amount of hydrogen crossover at the membrane in the absence of the metallic layer.

21 . The electrolysis cell of claim 19 , wherein:

the metallic layer comprises a semicontinuous or porous layer of platinum, gold, or any combination comprising at least one of the foregoing.