Abstract: The durability of a polymer electrolyte fuel cell is very significantly improved by using a tightening pressure of about 2 to 4 kgf/cm2 of area of electrode; or a tightening pressure of about 4 to 8 kgf/cm2 of contact area between electrode and separator plate; or by selecting a value not exceeding about 1.5 mS/cm2 for the short-circuit conductivity attributed to the DC resistance component in each unit cell; or by selecting a value not exceeding about 3 mA/cm2 for the hydrogen leak current per area of electrode of each MEA. Further, in a method of manufacturing or an inspection method for a polymer electrolyte fuel cell stack, fuel cells having high durability can be efficiently manufactured by removing such MEAs or unit cells using such MEAs or such cell stacks having short-circuit conductivity values and/or hydrogen leak current values exceeding predetermined values, respectively.

Abstract: A decrease in voltage in a polymer electrolyte fuel cell comprising stack of unit cells caused by the temperature difference between the cells located at the ends and the other cells due to a differential in heat dissipation from end plates is prevented by controlling the cooling temperature of the cells closest to the end plates of the fuel cell without affecting the output voltage of the cells in the middle by not including a coolant flow channel in the conductive separator plate between at least one of the end plates and the unit cell located closest to the one of the end plates.

Abstract: A polymer electrolyte fuel cell including a plurality of membrane electrode assemblies and a plurality of conductive separators, wherein the plurality of conductive separators include at least one separator comprising: a fuel gas inlet-side manifold aperture; a fuel gas outlet-side manifold aperture; a gas flow channel for fuel gas formed on an anode-side of the separator; an inlet-side through hole and an outlet-side through hole penetrating the separator which are formed at an inlet-side end and an outlet-side end of the gas flow channel for fuel gas; and an inlet-side connection groove and an outlet-side connection groove for connecting the inlet-side and outlet-side through holes with the fuel gas inlet-side manifold aperture and the fuel gas outlet-side manifold aperture, respectively, which are formed on a cathode-side of the separator.

Abstract: A polymer electrolyte fuel cell of the present invention includes conductive separator plates comprising molded plates of a composition comprising a binder, conductive carbon particles whose average particle diameter is not less than 50 ?m and not more than ? of the thickness of the thinnest portion of the conductive separator plate, and at least one of conductive carbon fine particles and micro-diameter carbon fibers. The separator plates do not require conventional cutting processes for gas flow channels, etc., and can be easily mass produced by injection molding and achieve a reduction in the cost.

Abstract: A highly reliable polymer electrolyte fuel cell includes an anode-side separator plate and a cathode-side separator plate that are provided with an anode-side sealing member and a cathode-side sealing member, respectively. The anode-side and cathode-side sealing members seal the cell in cooperation with a polymer electrolyte membrane at sealing parts where the anode-side and cathode-side sealing members are opposed to each other, thereby preventing gas from leaking out of gas flow channels. One of the anode-side and cathode-side sealing members has a pointed rib that comes in contact with the sealing parts in a linear manner, and the other sealing member comes in contact with the sealing parts surface to surface.

Abstract: A decrease in voltage in a polymer electrolyte fuel cell comprising stack of unit cells caused by the temperature difference between the cells located at the ends and the other cells due to a differential in heat dissipation from end plates is prevented by controlling the cooling temperature of the cells closest to the end plates of the fuel cell without affecting the output voltage of the cells in the middle by not including a coolant flow channel in the conductive separator plate between at least one of the end plates and the unit cell located closest to the one of the end plates.

Abstract: A polymer electrolyte fuel cell may have a cell stack of a plurality of unit cells. Each of the unit cells includes a hydrogen-ion conductive polymer electrolyte membrane, an anode and a cathode sandwiching the polymer electrolyte membrane, an anode-side separator having a gas flow channel for supplying a fuel gas to the anode, and a cathode-side separator having a gas flow channel for supplying an oxidant gas to the cathode. A pair of current collector plates sandwiches the cell stack, and a pair of end plates clamps the cell stack and the current collector plates under pressure. The current collector plates have a conductive carbon material as a main component, and have a terminal section for connecting a power output cable in the vicinity of an inlet-side manifold for the fuel gas or the oxidant gas.

Abstract: A polymer electrolyte fuel cell of the present invention includes a hydrogen ion-conductive polymer electrolyte membrane, an anode and a cathode sandwiching the hydrogen ion-conductive polymer electrolyte membrane, an anode-side conductive separator plate having a gas flow channel for supplying a fuel gas to the anode, and a cathode-side conductive separator plate having a gas flow channel for supplying an oxidant gas to the cathode.

Abstract: A polymer electrolyte fuel cell may include a stack of unit cells that each have a hydrogen-ion conductive polymer electrolyte membrane and an anode and a cathode sandwiching the polymer electrolyte membrane. Separators are provided between each two adjacent unit cells and include channels for supplying fuel and oxidant gas to the anode and the cathode. Anode side and cathode side current collector plates sandwich the stack of unit cells. The anode side current collector plate has a terminal section for a power output coupling and is located closer to an inlet-side manifold than to an outlet-side manifold for the fuel gas. The cathode side current collector plate has a terminal section for a power output coupling and is located closer to an inlet-side manifold than to an outlet-side manifold for the oxidant gas.

Abstract: A separator plate for a polymer electrolyte fuel cell having excellent conductivity and moldability is provided. The separator plate is injection molded, using different compounds for molding the portion that requires conductivity and the portion that does not require conductivity. The separator plate comprises: an electronic conductor portion containing conductive carbon; and an insulating portion surrounding the electronic conductor portion. The electronic conductor portion has a first flow channel of a gas or cooling water on one side and has a second flow channel of a gas or cooling water on the other side.

Abstract: A decrease in voltage in a polymer electrolyte fuel cell comprising stack of unit cells caused by the temperature difference between the cells located at the ends and the other cells due to a differential in heat dissipation from end plates is prevented by controlling the cooling temperature of the cells closest to the end plates of the fuel cell without affecting the output voltage of the cells in the middle by not including a coolant flow channel in the conductive separator plate between at least one of the end plates and the unit cell located closest to the one of the end plates.

Abstract: The durability of a polymer electrolyte fuel cell is very significantly improved by using a tightening pressure of about 2 to 4 kgf/cm2 of area of electrode; or a tightening pressure of about 4 to 8 kgf/cm2 of contact area between electrode and separator plate; or by selecting a value not exceeding about 1.5 mS/cm2 for the short-circuit conductivity attributed to the DC resistance component in each unit cell; or by selecting a value not exceeding about 3 mA/cm2 for the hydrogen leak current per area of electrode of each MEA. Further, in a method of manufacturing or an inspection method for a polymer electrolyte fuel cell stack, fuel cells having high durability can be efficiently manufactured by removing such MEAs or unit cells using such MEAs or such cell stacks having short-circuit conductivity values and/or hydrogen leak current values exceeding predetermined values, respectively.

Abstract: A fuel cell including a cell stack including plural electrically conductive separator plates and MEAs (electrolyte membrane-electrode assemblies) inserted among the separator plates. The fuel cell further includes gas communication grooves, where the gas communication grooves on one main surface of each separator plate are positioned to correspond to the ribs on the other main surface thereof, whereby thin wall portions in the separator plate can be avoided as much as possible, thereby to solve above described problems.

Abstract: A fuel cell having high operation performance and reliability is provided by optimizing the shape and properties of a gas diffusion layer and the dimensions of a gas flow channel. The fuel cell evenly supplies a reaction gas to the catalyst of a catalyst layer and promptly discharges excessive water generated therein. The gas diffusion layer of the MEA comprises a first section having a surface A coming in direct contact with a separator plate and a second section having a surface B facing the gas flow channel of the separator plate. The porosity of the first section is lower than the porosity of the second section, and the second section protrudes into the gas flow channel, which has sufficient width and depth for the protrusion of the gas diffusion layer, and the width of a rib formed by the gas flow channel is sufficiently narrow.

Abstract: A conductive separator plate for a polymer electrolyte fuel cell is disclosed which includes a cell stack and a plurality of conductive separator plates, the conductive separator plates being formed of a carbon powder and a binder, the conductive separator plates having a main portion which is raised from a peripheral portion surrounding the main portion, the main portion being in contact with an anode or cathode of the fuel cell and being provided with a gas flow path for supplying a fuel gas to the anode or a gas flow path for supplying an oxidant gas to the cathode.

Abstract: The present invention relates to a polymer electrolyte fuel cell comprising: an electrolyte membrane-electrode assembly including an anode, a cathode and a polymer electrolyte membrane interposed therebetween; an anode-side conductive separator plate having a gas flow channel for supplying a fuel gas to the anode; and a cathode-side conductive separator plate having a gas flow channel for supplying an oxidant gas to the cathode. A conductive separator plate made of carbon has poor wettability with water. This has posed the disadvantage that variations in performance are induced by nonuniform gas distribution among cells due to the accumulation of product water or humidifying water in the gas flow channel on the surface of the separator plate. The present invention employs a conductive separator plate comprising a conductive carbon having a hydrophilic functional group, at least in a portion of the gas flow channels, thereby preventing water from accumulating in the gas flow channels.

Abstract: A polymer electrolyte fuel cell including: a hydrogen ion conductive polymer electrolyte membrane; a pair of electrodes sandwiching the membrane; a pair of conductive separators each having a gas flow channel, one of which supplies a fuel gas to one of the electrodes and the other supplies an oxidant gas to the other electrode; and gaskets, each of which is sandwiched between the conductive separator and the hydrogen ion conductive polymer electrolyte membrane to surround the periphery of the electrode and the gas flow channel, wherein a gram of the conductive separator or the gasket, which is kept immersed in water of 80 to 100° C. for 50 hours, leaches into the water not more than 300 &mgr;g of TOC, not more than 50 &mgr;g of ammonium ion, not more than 50 &mgr;g of chloride ion, not more than 20 &mgr;g of bromide ion and not more than 10 &mgr;g of sulfurous acid ion.

Abstract: A polymer electrolyte fuel cell of the present invention includes conductive separator plates comprising molded plates of a composition comprising a binder, conductive carbon particles whose average particle diameter is not less than 50 &mgr;m and not more than ⅓ of the thickness of the thinnest portion of the conductive separator plate, and at least one of conductive carbon fine particles and micro-diameter carbon fibers. The separator plates do not require conventional cutting processes for gas flow channels, etc., and can be easily mass produced by injection molding and achieve a reduction in the cost.

Abstract: A polymer electrolyte fuel cell including a plurality of membrane electrode assemblies and a plurality of conductive separators, wherein the plurality of conductive separators include at least one separator comprising: a fuel gas inlet-side manifold aperture; a fuel gas outlet-side manifold aperture; a gas flow channel for fuel gas formed on an anode-side of the separator; an inlet-side through hole and an outlet-side through hole penetrating the separator which are formed at an inlet-side end and an outlet-side end of the gas flow channel for fuel gas; and an inlet-side connection groove and an outlet-side connection groove for connecting the inlet-side and outlet-side through holes with the fuel gas inlet-side manifold aperture and the fuel gas outlet-side manifold aperture, respectively, which are formed on a cathode-side of the separator.

Abstract: A polymer electrolyte fuel cell includes a stack of unit cells each including a hydrogen-ion conductive polymer electrolyte membrane, an anode and a cathode sandwiching the polymer electrolyte membrane, an anode-side separator having a gas flow channel for supplying a fuel gas to the anode, and a cathode-side separator having a gas flow channel for supplying an oxidant gas to the cathode. A pair of current collector plates sandwiches the cell stack, and a pair of end plates clamps the cell stack and the current collector plates under pressure. The current collector plates include a conductive carbon material and have a terminal section for connecting a power output coupling in the vicinity of an inlet-side manifold for the fuel gas or the oxidant gas.