Electrochemical Cell Stack Design
In one embodiment, an electrochemical cell comprises: a membrane electrode assembly comprising a first active area and an opposingly positioned second active area, and a flow field support member disposed adjacent to said membrane electrode assembly. Each of the active areas comprises an electrode, and has a length to width ratio configured such that, during use of the electrochemical cell, a temperature differential measured across the shortest distance from a center of the active areas to an edge of the active areas is less than about 15° C. The flow field support member has a flow region that aligns with either the first active area or the second active area.
1 . An electrochemical cell, comprising:
a membrane electrode assembly comprising a first active area and an opposingly positioned second active area, each of said active areas comprises an electrode, and has a length to width ratio such that a temperature differential measured across the shortest distance from a center of each of said active areas to an edge of said active areas is less than about 15° C.; and
a flow field support member disposed adjacent to said membrane electrode assembly, said flow field support member having a flow region that aligns with either said first active area or said second active area.
2 . The electrochemical cell of claim 1 , further comprising a urethane spring disposed adjacent to said flow field support member to urge said flow field support member against said membrane electrode assembly to maintain said flow field support member and said membrane electrode assembly in a compressive relationship.
3 . The electrochemical cell of claim 1 , further comprising tabs disposed at peripheral edges of said membrane electrode assembly and said flow field support member, said tabs being engageable with holes disposed in a side plate to maintain said membrane electrode assembly and said flow field support member in alignment.
4 . The electrochemical cell of claim 1 , wherein each of said length to width ratio is greater than or equal to about 4:1.
5 . The electrochemical cell of claim 1 , further comprising a heater disposed at said flow field support member adjacent to said membrane electrode assembly.
6 . The electrochemical cell of claim 5 , wherein said heater is an electrically-resistive element.
7 . The electrochemical cell of claim 1 , wherein the temperature differential is less than about 10° C.
8 . A membrane electrode assembly for an electrochemical cell, said membrane electrode assembly comprising:
a proton exchange membrane having a first active area and a second active area, said first active area having a length to width ratio configured such that, during use of the membrane electrode assembly, a first temperature differential measured across the shortest distance from a center of said first active area to an edge of said first active area is less than about 15° C.;
a first electrode disposed at said first active area; and
a second electrode disposed at said second active area.
9 . The membrane electrode assembly of claim 8 , wherein a length to width ratio of said active areas is greater than or equal to about 4:1.
10 . The membrane electrode assembly of claim 8 , wherein during use of said membrane electrode assembly, said second active area has a second temperature differential across the shortest distance from a center of said second active area to an edge of said second active area of less than about 15° C.
11 . The membrane electrode assembly of claim 8 , wherein said first temperature differential and the second temperature differential are less than about 10° C.