Abstract: An electrode/separator assembly for use in an electrochemical cell includes a porous composite layer having a total thickness in the range of about 4 ?m to about 50 ?m comprising inorganic particles having an average aggregate particle size in the range of about 0.5 ?m to about 6 ?m in an electrochemically stable polymer matrix.

Abstract: A freeze tolerant fuel cell power plant (10) includes at least one fuel cell (12), a coolant loop (18) including a freeze tolerant accumulator (22) for storing and separating a water immiscible fluid and water coolant or water component, a direct contact heat exchanger (56) for mixing the water immiscible fluid and the water coolant within a mixing region (72) of the heat exchanger (56), a coolant pump (21) for circulating the coolant through the coolant loop (18), a radiator loop (84) for circulating the water immiscible fluid through the heat exchanger (56), and a radiator (86) for removing heat from the coolant. The plant (10) utilizes the water immiscible fluid during steady-state operation to cool the fuel cell and during shut down of the plant to displace water from the fuel cell (12) to the freeze tolerant accumulator (22).

Abstract: A freeze tolerant fuel cell power plant (10) includes at least one fuel cell (12), a coolant loop (18) including a freeze tolerant accumulator (22) for storing and separating a water immiscible fluid and water coolant, a direct contact heat exchanger (56) for mixing the water immiscible fluid and the water coolant within a mixing region (72) of the heat exchanger (56), a coolant pump (21) for circulating the coolant through the coolant loop (18), a radiator loop (84) for circulating the water immiscible fluid through the heat exchanger (56), and a radiator (86) for removing heat from the coolant. The plant (10) utilizes the water immiscible fluid during steady-state operation to cool the fuel cell and during shut down of the plant to displace water from the fuel cell (12) to the freeze tolerant accumulator (22).

Abstract: A freeze tolerant fuel cell power plant (10) includes at least one fuel cell (12), a coolant loop (42) having a porous water transport plate (44) secured in a heat and mass exchange relationship with the fuel cell (12) and a coolant pump (46) for circulating a coolant through the plate (44) and for transferring water into or out of the plate (44) with the coolant. A coolant heat exchanger (52) removes heat from the coolant, and an accumulator (66) stores the coolant and fuel cell product water and directs the product water out of the accumulator (66). The coolant is a two-component mixed coolant liquid circulating through the coolant loop (42) consisting of between 80 and 95 volume percent of a low freezing temperature water immiscible fluid component and between 5 and 20 volume percent of a water component.

Abstract: A fuel cell stack (10) includes a reaction portion (20) having an end cell (12) secured adjacent to a current collector (30). The collector (30) has a sensible heat no greater than a sensible heat of the end cell (12) and an electrical resistivity no greater than 100 micro-ohms centimeters. An insulator (40) is secured adjacent the collector (30) and has a thermal conductivity that is no greater than 0.500 Watts per meter per degree Kelvin. Because of the low sensible heat of the current collector (30) and low rate of heat transfer of the insulator (40), heat does not readily leave the end cell (12) resulting in a rapid heating of the end cell (12), thereby avoiding freezing and accumulation of product water in the end cell (12) during start up in subfreezing conditions.

Abstract: A fuel cell system having a stack of proton exchange membrane fuel cells is operated in sub-freezing temperatures by draining any liquid water from the fuel cell water flow passages upon or after the previous shut-down of the stack before freezing can occur, and, thereafter a) starting-up the stack by directing fuel and oxidant reactants into the cell and connecting a load to the stack; b) using heat produced by the stack to increase the operating temperature of the stack to melt ice within the stack; and, c) upon the stack operating temperature reaching at least 0° C., circulating anti-freeze through stack coolers to maintain the temperature of the stack low enough to maintain a sufficiently low water vapor pressure within the cells to prevent cell dry out for at least as long as there is insufficient liquid water to circulate through the water flow passages.