Abstract: A fuel cell system and method for driving the same is disclosed. In one embodiment, the fuel cell system includes i) a fuel supply unit, ii) a fuel cell stack in fluid communication with the fuel supply unit, wherein the fuel cell stack has a fuel inlet and a fuel outlet and iii) a bypass pipe configured to transfer fuel received from the fuel supply unit to a fuel outflow pipe connected to the fuel outlet. In one embodiment, the driving method includes i) receiving fuel from a fuel supply unit, ii) transferring the received fuel to a fuel outflow pipe connected to a fuel outlet of a fuel cell stack and iii) discharging non-reacted fuel from a fuel inlet of the fuel cell stack.

Abstract: A fuel cell system according to exemplary embodiments of the present invention includes a fuel cell stack that generates electrical energy through the electrochemical reaction of fuel and oxidant, a fuel supply unit for supplying the fuel to the fuel cell stack, and an oxidant supply unit for supplying the oxidant to the fuel cell stack. The fuel supply unit includes a fuel permeation membrane between a space where fuel recovered from the fuel cell stack is positioned and a space where stored fuel is positioned. The fuel cell system enables easy control of the concentration of fuel supplied to the fuel cell stack.

Abstract: A direct methanol fuel cell (DMFC) system including: a separator receiving a gas-liquid mixture discharged from a stack and separating the mixture to gas and a liquid; a methanol cartridge storing high concentration methanol; and a fuel mixer for methanol dilution. The separator and the fuel mixer are separate structures, each including an agitator for stirring a liquid. The agitators can be on the same rotation axis.

Abstract: An activation method and system to selectively activate defective cells in a laminated fuel cell stack. The system includes a tank to store a polar solvent used to activate the cells; a body including a transfer unit to transfer the polar solvent to the fuel cell stack and a control unit to control the transfer unit; and a nozzle coupled to the body, to be inserted into an inlet manifold of the fuel cell stack. The nozzle has an opening positioned opposite to a channel inlet of at least one non-activated cell of the plurality of cells, to jet the polar solvent into only a channel of the non-activated cell, through the opening.

Abstract: A direct methanol type fuel cell stack and a direct methanol type fuel cell system using the same are discussed. The fuel cell stack may be configured to allow a concentration gradient of a mixed fuel in which fuel and water are not properly mixed to be uniform without increasing the volume of the fuel cell stack. The fuel cell stack may include at least one cell having an anode, a cathode, an electrolyte separating the anode and the cathode and a mixer coupled to the anode. The mixer may be configured to mix fuel and water and achieve a uniform concentration of the mixed fuel supplied to the anode.

Abstract: A fuel cell separator capable of improving stack performance by reducing the deviation in cell performance and diminishing dead space, and a fuel cell stack using the same are disclosed. The fuel cell separator may include a base member, a first channel group disposed on a surface of the base member and a second channel group disposed on the surface of the base member. The first channel group may include at least one channel and the second channel group may include at least one channel. The first channel group and the second channel group may extend parallel to each other in a first region of the surface and independent from each other in a second region of the surface.

Abstract: A direct methanol fuel cell (DMFC) that includes: an anode, a cathode, and a membrane disposed therebetween; a bipolar plate having a flow channel to supply a fluid to the anode; and a flow restrictor installed in the flow channel, to restrict the flow of the fluid.

Abstract: There are provided a coupling structure of a fuel cell stack capable of precisely and rapidly assembling a stack by a predetermined height. The fuel cell stack includes a membrane electrode assembly for generating electricity, separators disposed on both sides of the membrane electrode assembly, first and second end plates disposed on both sides an accumulated body of the membrane electrode assembly and the separators, and a coupling device penetrating the first end plate, the membrane electrode assembly, and the separators, and fastened into a fixing hole of the second end plate. The coupling device includes a head, a body, a thread, and a step formed at an interface between the body and the thread such that a cross-sectional area of the body is greater than a cross-sectional area of the thread, and stops the fixing when the step contacts the second end plate.

Abstract: Disclosed is a separator for a fuel cell stack. The separator includes a plate having a first opening and a second opening on a surface thereof. A field or a channel is formed on the surface of the plate. The field has a first end and a second end. A field inlet is formed on the surface of the plate and connects the first end of the field to the first opening, and a field outlet is formed on the surface of the plate and connects the second end of the field to the second opening. An area of a cross-section of the field inlet, which is cut perpendicular to the surface of the plate, is smaller than an area of a cross-section of the field outlet, which is cut perpendicular to the surface of the plate.

Abstract: A fuel cell stack including an electricity generating unit for generating electrical energy by electrochemically reacting a fuel and an oxidizing agent, the electricity generating unit including: a first separator; a second separator; a membrane electrode assembly (MEA) between the first separator and the second separator, each of the first and second separators including a channel on a surface facing the MEA and a manifold in the surface facing the MEA, the manifold communicating with the channel; and a gasket, positioned at an outer circumference portion of an area where the MEA is positioned, for sealing a space between the first and second separators and for covering an open area of a channel extension area of at least one of the first and second separators where the manifold communicates with the channel.

Abstract: A fuel cell stack includes a plurality of membrane electrode assemblies (MEAs) and a stamped metal separator. The metal separator is positioned between the membrane electrode assemblies. The separator includes at least one channel on both surfaces of the separator formed by a stamping process. The separator comprises a plurality of holes, each of which form a manifold communicating with each the channels.

Abstract: A fuel cell stack comprising a multitude of membrane-electrode assemblies stacked with a separator interposed therebetween is characterized in that an MEA of first a property having an anode and a cathode, and the MEA of second property having an anode electrode and a cathode electrode are stacked. Preferably the MEA of the first property is a hydrocarbon-based MEA and the MEA of the second property is a fluorine-based MEA.

Abstract: Disclosed is a separator for a fuel cell. The separator includes a plate configured to face an anode electrode and a cathode electrode of a fuel cell to generate electricity by electrochemical reaction between hydrogen and oxygen. The separator includes channels through which fluid can flow and ribs forming the channels. At least one of the ribs includes a sloping end at an outlet end thereof. The sloping end has a first inclination angle relative to a surface of the plate. Water produced in the cathode electrode is easily discharged and air is smoothly supplied to the cathode electrode, thereby enhancing the power generation efficiency of the fuel cell.

Abstract: A fuel cell stack includes at least one electric generator with a membrane electrode assembly and separators placed at both sides of the membrane electrode assembly. A plurality of common passages are arranged at a surface of at least one of the separators to permit the flow of oxygen and a coolant. A guide is formed at an inlet of the common passage to guide the oxygen and the coolant into the common passage.

Abstract: A cooling system for a fuel cell stack is provided. The fuel cell stack includes an electricity generating assembly having a plurality of unit cells, wherein each of the unit cells comprises common passages. An oxidant used to generate electric energy and a coolant used to cool the stack may both flow through the common passages.