Electrochemical device and method for controlling corrosion

1. An electrochemical device comprising:

a plurality of electrode assemblies defining a plurality of electrochemically active areas;

a non-electrically-conductive manifold including a common manifold passage to transport ionic-conductive fluids, wherein the ionic-conductive fluids contain one or more reactants that readily undergo oxidation and reduction reactions that result in different oxidation states and enable the storage of energy; and

a plurality of branch passages that extend, respectively, between the plurality of electrochemically active areas and the common manifold passage, each of the plurality of branch passages including a first region and a second region that differ in surface area.

2. The electrochemical device as recited in claim 1 , wherein each of the plurality of electrode assemblies includes a first porous electrode, a second porous electrode and a separator layer between the first porous electrode and the second porous electrode, wherein the first porous electrode and the second porous electrode each span over an area that is larger than the separator layer.

3. The electrochemical device as recited in claim 2 , wherein the first porous electrode and the second porous electrode include respective overhang portions that extend beyond a side of the separator layer, each of the overhang portions bounding the second region of a respective one of the plurality of branch passages but not bounding the first region.

4. The electrochemical device as recited in claim 1 , wherein the first region and the second region differ in wall surface roughness.

5. The electrochemical device as recited in claim 1 , wherein the second region is partially bounded by an electrically-conductive surface that is outside of the plurality of electrochemically active areas.

6. The electrochemical device as recited in claim 5 , wherein the first region is bounded by non-conductive polymeric walls.

7. The electrochemical device as recited in claim 1 , further comprising a bipolar plate that includes a plurality of channels that are fluidly connected with the plurality of branch passages, the plurality of channels being in the plurality of electrochemically active areas.

8. The electrochemical device as recited in claim 7 , where in the plurality of channels run between channel walls and each of the channel walls includes a tapered end.

9. The electrochemical device as recited in claim 8 , wherein the tapered end tapers to a point.

10. The electrochemical device as recited in claim 8 , wherein the tapered end tapers to a rounded end.

11. The electrochemical device as recited in claim 8 , wherein the plurality of channels are interdigitated channels.

12. The electrochemical device as recited in claim 7 , wherein the first porous electrode and the second porous electrode each span over an area that is larger than the bipolar plate.

13. The electrochemical device as recited in claim 2 , further comprising a seal around the perimeter of the electrode assembly, wherein the seal integrates the electrodes and the separator layer in a membrane-electrode assembly.

14. The electrochemical device as recited in claim 3 , wherein the overhang portions serve as sources or sinks for shut currents of the ionic-conductive fluids.

15. The electrochemical device as recited in claim 4 , wherein the first region is relatively smooth compared to the second region.

16. The electrochemical device as recited in claim 11 , wherein the interdigitated channels have alternating open ends and closed ends.

17. The electrochemical device as recited in claim 1 , wherein the electrochemical device is a flow battery.

18. The electrochemical device as recited in claim 1 , wherein the ion conductive fluids are vanadium liquid electrolytes.