Design strategies for corrosion mitigation
Fuel cells are provided that are at least partially resistant to corrosion, including the use of components that are comprised of materials that are at least partially resistant to corrosion. The fuel cells include subgasket materials and designs, involving geometric arrangements of the subgasket that reduce oxygen permeation from, the cathode to the anode side of the membranes and/or hydrogen permeation from the anode to the cathode side of the membranes. In addition to using protonically non-conductive subgasket materials with lower oxygen and/or hydrogen permeabilities, versus ionomeric subgaskets which are protonically conducting and have high O 2 permeation rates, the elimination of the microporous layer (e.g., coated onto the diffusion medium) directly beneath the permeable subgasket materials will also reduce production of corrosive species. The elimination of direct contact between the bipolar plate material surface and PFSA ionomer membrane material also prevents corrosion to the metal bipolar plates.
1 . A fuel cell, comprising:
a conductive member having a region of stagnant flow;
a diffusion media layer adjacent to the electrically conductive member;
a membrane layer;
at least one catalyst layer adjacent to the membrane layer, wherein the at least one catalyst layer is adjacent to the diffusion media layer, wherein the at least one catalyst layer is spaced away from the region of stagnant flow; and
at least one subgasket layer adjacent to the membrane layer, wherein the at least one subgasket layer is adjacent to the diffusion media layer, wherein the at least one subgasket layer is in proximity to the region of stagnant flow, wherein the at least one catalyst layer and the at least one subgasket layer are spaced away from one another.
2 . The invention according to claim 1 , wherein the conductive member is a bipolar plate.
3 . The invention according to claim 1 , wherein the conductive member is comprised of a metallic material.
4 . The invention according to claim 1 , wherein the conductive member is comprised of stainless steel.
5 . The invention according to claim 1 , wherein the subgasket layer is comprised of a non-conductive material.
6 . The invention according to claim 1 , wherein the subgasket layer is comprised of a protonically non-conductive material.
7 . The invention according to claim 1 , wherein the subgasket layer is comprised of a material having substantially low oxygen permeability.
8 . The invention according to claim 1 , wherein the subgasket layer is comprised of a material having substantially low hydrogen permeability.
9 . The invention according to claim 1 , wherein the subgasket layer is comprised of a material selected from the group consisting of a polymeric material, a non-corrosive metallic material, and combinations thereof.
10 . The invention according to claim 1 , further comprising a pair of catalyst layers.
11 . The invention according to claim 1 , further comprising a pair of subgasket layers.
12 . The invention according to claim 1 , wherein the region of stagnant flow comprises a region selected from the group consisting of a dimpled area formed on the electrically conductive member, a wide land at the periphery of a membrane electrode assembly, and combinations thereof.
13 . The invention according to claim 1 , further comprising a microporous layer disposed between the diffusion media layer and at least one of the catalyst layer and the subgasket layer.
14 . The invention according to claim 1 , wherein the conductive member does not contact the membrane layer.
15 . A fuel cell, comprising:
a conductive member having a region of stagnant flow;
a diffusion media layer adjacent to the electrically conductive member;
a membrane layer;
a pair of catalyst layers disposed about the membrane layer, wherein one of the catalyst layers is adjacent to the diffusion media layer, wherein the pair of catalyst layers are spaced away from the region of stagnant flow; and
a pair of subgasket layers disposed about the membrane layer, wherein one of the subgasket layers is adjacent to the diffusion media layer, wherein the pair of subgasket layers are in proximity to the region of stagnant flow, wherein the pair of catalyst layers and pair of subgasket layers is spaced away from one another.
16 . The invention according to claim 15 , wherein the conductive member is a bipolar plate.
17 . The invention according to claim 15 , wherein the conductive member is comprised of a metallic material.
18 . The invention according to claim 15 , wherein the conductive member is comprised of stainless steel.
19 . The invention according to claim 15 , wherein the subgasket layer is comprised of a non-conductive material.
20 . The invention according to claim 15 , wherein the subgasket layer is comprised of a protonically non-conductive material.
21 . The invention according to claim 15 , wherein the subgasket layer is comprised of a material having substantially low oxygen permeability.
22 . The invention according to claim 15 , wherein the subgasket layer is comprised of a material having substantially low hydrogen permeability.
23 . The invention according to claim 15 , wherein the subgasket layer is comprised of a material selected from the group consisting of a polymeric material, a non-corrosive metallic material, and combinations thereof.
24 . The invention according to claim 15 , wherein the region of stagnant flow comprises a region selected from the group consisting of a dimpled area formed on the electrically conductive member, a wide land at the periphery of a membrane electrode assembly, and combinations thereof.
25 . The invention according to claim 15 , further comprising a microporous layer disposed between the diffusion media layer and at least one of the pair of catalyst layers and the pair of subgasket layers.
26 . The invention according to claim 15 , wherein the conductive member does not contact the membrane layer.
27 . A fuel cell, comprising:
a conductive member having first and second free-flowing channels formed therein and first and second land areas formed about the second free-flowing channel, wherein the conductive member is substantially free of regions of stagnant flow;
a diffusion media layer adjacent to the electrically conductive member, a portion of the diffusion media layer overlapping the second land area;
a membrane layer;
at least one catalyst layer adjacent to the membrane layer, wherein the at least one catalyst layer is adjacent to the diffusion media layer, wherein the at least one catalyst layer is spaced away from the second land area; and
at least one subgasket layer adjacent to the membrane layer, wherein the at least one subgasket layer is adjacent to and at least partially overlaps the diffusion media layer in proximity to the second land area, wherein the at least one catalyst layer and the at least one subgasket layer are spaced away from one another.
28 . The invention according to claim 27 , wherein the conductive member is a bipolar plate.
29 . The invention according to claim 27 , wherein the conductive member is comprised of a metallic material.
30 . The invention according to claim 27 , wherein the conductive member is comprised of stainless steel.
31 . The invention according to claim 27 , wherein the subgasket layer is comprised of a non-conductive material.
32 . The invention according to claim 27 , wherein the subgasket layer is comprised of a protonically non-conductive material.
33 . The invention according to claim 27 , wherein the subgasket layer is comprised of a material having substantially low oxygen permeability.
34 . The invention according to claim 27 , wherein the subgasket layer is comprised of a material having substantially low hydrogen permeability.
35 . The invention according to claim 27 , wherein the subgasket layer is comprised of a material selected from the group consisting of a polymeric material, a non-corrosive metallic material, and combinations thereof.
36 . The invention according to claim 27 , further comprising a pair of catalyst layers.
37 . The invention according to claim 27 , further comprising a pair of subgasket layers.
38 . The invention according to claim 27 , further comprising a microporous layer disposed between the diffusion media layer and at least one of the catalyst layer and the subgasket layer.
39 . The invention according to claim 27 , wherein the conductive member does not contact the membrane layer.
40 . The invention according to claim 27; wherein the distance of the first or second land areas is less than the distance of the second free-flowing channel.
41 . The invention according to claim 27 , wherein the distance of the first or second land areas is no more than half of the distance of the second free-flowing channel.