Abstract: An electrochemical fuel cell having an anode, an ion transfer membrane and a cathode has liquid water delivered to the fluid flow channels within the cathode so as to maintain a relative humidity of 100% throughout the fluid flow channels. A calibration method and apparatus is described for determining an optimum quantity or range of quantities of liquid water to be delivered to the cathode fluid flow channels under varying operating conditions. An operating method and apparatus is described that ensures an optimum quantity of liquid water is delivered to the cathode fluid flow channels under varying operating conditions.

Abstract: An electrochemical fuel cell having an anode, an ion transfer membrane and a cathode has liquid water delivered to the fluid flow channels within the cathode so as to maintain a relative humidity of 100% throughout the fluid flow channels. A calibration method and apparatus is described for determining an optimum quantity or range of quantities of liquid water to be delivered to the cathode fluid flow channels under varying operating conditions. An operating method and apparatus is described that ensures an optimum quantity of liquid water is delivered to the cathode fluid flow channels under varying operating conditions.

Abstract: A fuel cell comprising a membrane-electrode assembly having an anode electrode face; an anode plate adjacent said membrane-electrode assembly electrode face and coupled thereto by a sealing gasket. The sealing gasket, electrode face and anode plate together define a fluid containment volume for delivery of anode fluid to the electrode face. A sheet of porous diffuser material is situated in the fluid containment volume and having at least one plenum defined between at least one lateral edge of the sheet of diffuser material and the sealing gasket. Fluid for delivery to an active surface of the membrane-electrode assembly may be delivered by the plenum and by diffusion through the diffuser material to such an extent that fluid flow channels in the anode plate are not required.

Abstract: An electrochemical fuel cell having an anode, an ion transfer membrane and a cathode has liquid water delivered to the fluid flow channels within the cathode so as to maintain a relative humidity of 100% throughout the fluid flow channels. A calibration method and apparatus is described for determining an optimum quantity or range of quantities of liquid water to be delivered to the cathode fluid flow channels under varying operating conditions. An operating method and apparatus is described that ensures an optimum quantity of liquid water is delivered to the cathode fluid flow channels under varying operating conditions.

Abstract: One or more operating parameters, such as electrical current flow from and air flow to, a fuel cell stack within a fuel cell assembly is periodically modulated during rehydration intervals to intermittently increase hydration levels of the fuel cell stack independently of the electrical current demand on the fuel cell assembly from an external load, while maintaining electrical current delivery to that external load.

Abstract: An electrochemical fuel cell includes a membrane-electrode assembly (MEA) having a cathode face and an anode face. The MEA is between a cathode fluid flow field plate and an anode fluid flow field plate. A diffusion structure is between the MEA and a corresponding fluid flow field plate, which is either the cathode fluid flow field plate or the anode fluid flow field plate. The diffusion structure has a first face in contact with, or adjacent to, the MEA and a second face in contact with, or adjacent to, the corresponding fluid flow field plate. The diffusion structure includes a first layer having a first level of hydrophobicity and a second layer that is hydrophilic. The second layer is adjacent to the corresponding fluid flow field plate, and includes a hydrophilic binder material.

Abstract: One or more operating parameters, such as electrical current flow from and air flow to, a fuel cell stack within a fuel cell assembly is periodically modulated during rehydration intervals to intermittently increase hydration levels of the fuel cell stack independently of the electrical current demand on the fuel cell assembly from an external load, while maintaining electrical current delivery to that external load.

Abstract: An electrochemical fuel cell having an anode, an ion transfer membrane and a cathode has liquid water delivered to the fluid flow channels within the cathode so as to maintain a relative humidity of 100% throughout the fluid flow channels. A calibration method and apparatus is described for determining an optimum quantity or range of quantities of liquid water to be delivered to the cathode fluid flow channels under varying operating conditions. An operating method and apparatus is described that ensures an optimum quantity of liquid water is delivered to the cathode fluid flow channels under varying operating conditions.

Abstract: Ail electrochemical fuel cell has a membrane-electrode assembly (MEA) having a cathode face and an anode face being disposed between a cathode fluid flow field plate and an anode fluid flow field plate. Each fluid flow field plate has fluid distribution conduits in a first surface thereof facing the respective cathode face or anode face of the MEA. A diffusion structure is disposed between the MEA and a respective one of the fluid flow field plates and has a first face in contact with or adjacent to the MEA and a second face in contact with or adjacent to the respective fluid flow field plate. The diffusion structure includes a first layer having a first level of hydrophobicity and a second layer being relatively hydrophilic compared to the first layer, the second layer being adjacent to the respective fluid flow field plate.