JP2002543566A - Freeze-resistant fuel cell system and method - Google Patents

Abstract

(57) Abstract: A frost-resistant fuel cell system and a method of operating the frost-resistant fuel cell system are disclosed. The freeze-tolerant fuel cell system separates the coolant loop (25) from the active membrane (12) by using gaskets (20, 21) sandwiched between the collector cell plates (18, 19). It is realized by. A method of operating a frost-resistant fuel cell system that includes flowing a coolant having a sufficiently low freezing point other than pure through a coolant loop 25 is disclosed. A method for starting and stopping the operation of the frost-resistant fuel cell system is also disclosed.

Description

DETAILED DESCRIPTION OF THE INVENTION

(Cross Reference of Related Application) [0001] The present application relates to a fuel cell and a system including a frost-resistant coolant (FUEL CEL).
L AND SYSTEM WITI (FREEZE TOLERANT CO
OLANTS), US Provisional Application No. 60 / filed April 23, 1999.
130, 801 relating to and claiming benefits. The entire contents of the provisional application are incorporated herein by reference.

FIELD OF THE INVENTION [0002] The present invention relates to fuel cell systems and, more particularly, to cooling systems for fuel cell systems. (Description of Related Art) A fuel cell is a device that generates electrical energy by directly converting chemical energy into electrical energy by an electrochemical reaction of fuel and oxygen supplied to the battery. It has a case that houses a typical battery, anode, cathode and electrolyte membrane. The electrolyte membrane is disposed between the anode and the cathode. A catalyst layer is disposed on the electrolyte-facing surface of each electrode. Suitable catalysts include nickel, silver, platinum,
In the case of a more stable zirconium oxide electrolyte, there is a base metal oxide. Platinum is most commonly used. Appropriate fuel material and oxidant are provided to the anode and cathode, respectively, and the fuel and oxidant react electrochemically to produce an electric current, and the end products of the reaction are recovered from the cell. Relatively simple types of fuel cells (commonly referred to as PEM fuel cells) use hydrogen and oxygen as the fuel and oxidant materials, respectively. Hydrogen combines with oxygen to form water and at the same time generates current and heat. More specifically, as shown in equation (1), hydrogen is consumed while emitting protons and electrons at the fuel cell anode.

(1) H ₂ → 2H ⁺ + 2e ⁻ anode reaction Protons are drawn into the fuel cell electrolyte. The generated electrons travel from the anode of the fuel cell to the anode terminal, and return to the cathode terminal and back to the cell cathode by electrical loading. The flow of ions through the electrolyte completes the circuit. Chemical reaction rates vary with location on the electrode and depend on local factors such as the concentrations of reactants and product products, and temperature. At the cathode, oxygen combines with electrons from the load and protons from the electrolyte to form water, as shown in equation (2).

(2) _1/2 O ₂ + 2H ⁺ + 2e → H ₂ O Cathodic Reaction A major advantage of fuel cells is that fuel cells can be used for fuels based on hydrocarbons or carbon, such as in conventional thermal power plants. Without having to go through any intermediate steps such as combustion
It means converting chemical energy directly into electrical energy. Fuel cells can be classified into several types depending on the electrolyte used. Relatively sophisticated fuel cells use electrolytes such as aqueous potassium hydroxide, concentrated phosphoric acid, condensed alkali carbonates, and stabilized zirconium oxide.

[0005] Since individual fuel cells can produce less than the desired voltage for a given application at full load, practical fuel cells require the following to achieve the desired voltage level: Several individual fuel cells are stacked in series by electrically connecting the cathode of one cell to the anode of an adjacent cell. Therefore, fuel cell stacks are commonly used.

[0006] The overall reaction in the battery (ie, the combination of water) is very exothermic. Therefore,
The rate of heat generation depends on the reaction rate and the heat flux across a given area of the fuel cell, and is proportional to the local reaction rate. Accordingly, there is a general need for a structure for cooling a fuel cell, which is generally designed based on a prominent peak heat flux. Water is generally used to cool the fuel cell.

[0007] PEM fuel cells generally require humidification to maintain the water content of the electrolyte membrane required for efficient fuel cell operation. Generally, a single water loop provides both humidification and fuel cell cooling.

In some fuel cell applications, such as in automotive applications, it may be necessary to initiate operation of a fuel cell stack having a core temperature below the freezing point of water. For example, SAE automobile standard (SAE automatic standa)
rd) operates between -40 ° C and 53 ° C and survives between -46 ° C and 66 ° C (
Storage). Numerous obstacles are encountered in attempting to operate fuel cells in applications below the freezing point of water. Water is known to expand significantly upon freezing. Freezing of water in a fuel cell system can destroy components of the fuel cell. Even if the freezing does not cause damage to the components, blockage of the fuel system line may occur, which may delay the start of operation of the fuel cell. Finally, for sub-zero applications, a coolant that freezes below the freezing point of water must be selected. The most available coolants with a freezing point lower than the freezing point of water, by binding to catalyst sites when such materials are allowed to contact the catalyst layer,
It is known to "poison" the catalyst layer. There is a need for a frost resistant fuel cell structure and method that allows reliable fuel cell operation at temperatures well below the freezing temperature of water.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel cell system that can be used in a sub-zero environment. Another object of the present invention is to provide a fuel cell system that can use a coolant other than a coolant that is compatible with the MEA.

Yet another object of the present invention is to provide a technique for removing water from a fuel cell when operation is stopped and rapidly reheating the fuel cell when operation is started. These and other objects of the invention are achieved by a number of embodiments that embody the features and advantages of the invention. The present invention may have a freeze-tolerant fuel cell system comprising at least one fuel cell formed from a pair of collector plates having a series of channels for a reactant stream. A first gas diffusion layer and a second gas diffusion layer are disposed between the collector plates, and the membrane electrode assembly (MEA) includes a membrane sandwiched between the two electrode layers. An MEA disposed between the gas diffusion layers;
The reactants on each side of the MEA are substantially sealed from leaking to the other side of the MEA. The fuel cell stack may include the ME while the coolant stream cools the fuel cell.
At least one for flowing a coolant stream against the collector plate so as not to contact
And two coolant channels.

According to another aspect of the invention, the coolant flowing in the coolant channel is harmful to the MEA and must thus be physically isolated from the MEA. The surface of the coolant channel in contact with the coolant may be electrically insulated, or the coolant may be non-conductive. Said isolation may be provided by providing a gasket device around a coolant port extending through the collector plate. The gasket is preferably spaced from the gas diffusion layer. Alternatively, the cooling passage can be located outside the conductive part of the collector plate and be surrounded by the housing. The housing may be integrally formed with the collector plate or connected to the collector plate.

[0012] The fuel cell coolant loop provides edge cooing within the fuel cell.
ling) or a coolant layer may be provided on the outside of the collector plate. This coolant layer is provided immediately adjacent to each reactive fuel cell or in intermittent steps throughout the fuel cell stack.

According to another aspect of the invention, the interface between the peripheral port gasket and the reaction zone membrane is filled with a subgasket to prevent compromising mechanical and electrical edge effects in the membrane. Can be supported by In a preferred embodiment, the subgasket extends across the uncoated membrane portion between the port gasket and the gas diffusion layer. The sub gasket is FEP, TFE,
ETFE, PFA, CTFE, E- CTFE, may be formed of many materials including PVF ₂ and PVF.

To equip a fuel cell system for use in a sub-zero environment, the present invention provides
Related to shutdown and start-up to prevent the presence of a significant amount of water in the fuel cell when the temperature of the fuel cell falls below the freezing point of water, such as when the fuel cell system is not operating. Improvements and techniques are further contemplated.

During operation of the fuel cell, water can accumulate in the gas diffusion layer as well as in the flow path of the collector plate. According to one aspect of the invention, the discontinuity of the reactant channels in the collector plate establishes a region of flow through the gas diffusion layer. In this configuration, as part of the freeze-resistant operation shutdown operation, purge dry gas may be pumped into the fuel cell to collect and expel water not only from the channel but also from the gas diffusion layer.

Preferably, the surface of the channel is essentially impermeable to water to reduce the accumulation of residual water after a shutdown. Further, the surface of the channel may be essentially impermeable to all fluids.

To further assist in the effective removal of water during shutdowns, the fuel cell system according to the present invention provides a gas diffusion layer on one side of the membrane so as to increase the moisture gradient and the rate of water movement. A countercurrent may be provided therein. The reactant channels of each collector plate can be configured such that the direction of the reactant stream in one gas diffusion layer is opposite the direction of the reactant stream in another gas diffusion layer.

Another improvement that assists in water removal involves placing an outlet channel to take advantage of gravity. The fuel cell system according to the present invention has a plurality of reactant outlets, at least one of which is located below the channel, so that water removal can be assisted by gravity.

Effluent can be removed from the system or collected in a reservoir, such as a tank. The tank may be isolated or freezing resistant in a variety of ways, including direct dedicated sources, or heating from temporary sources, such as heat generation from the system's fuel processor or fuel cell. May be provided. During the rest phase, the water supply in the tank may freeze if the tank is designed to allow freezing expansion of the water.

In order to protect against mechanical damage of the collector plate due to freezing expansion of the remaining water, the walls of the channels may be tapered and have rounded corners. According to the present invention, the fuel cell system can become more resistant to freezing by incorporating an operation stop procedure that contributes to the freezing environment. The operation stopping step includes a step of condensing water vapor in the fuel stack by lowering a fuel cell system temperature, a step of removing water, a liquid, and a gas from the fuel cell, and humidifying the reaction gas line. Purging with unpurified gas and reducing the system pressure to a pressure approximately equal to atmospheric pressure may be included. These steps may be performed in a different order, or alternatively, may be started simultaneously.

The shutdown procedure may include a step of further increasing the heat of the fuel cell at or immediately prior to shutdown. One preferred step comprises operating the fuel stack in a mode that produces a pulsed current output.

During start-up, the presence of significant amounts of water before the fuel is heated above its freezing point can present a risk of damage due to freezing and expansion of the water. Thus, the technique according to the invention comprises a start-up procedure for introducing water so as to prevent freezing. These techniques include flowing a dried reactant gas through the reactant line to the fuel cell, measuring the temperature of the fuel cell, and reacting the reactant gas after the fuel cell temperature rises above a predetermined temperature. Starting the humidification of the water. The predetermined temperature can be the freezing point of water at atmospheric pressure. The start-up procedure may preferably include the step of increasing the heat of the fuel cell and pressurizing to a maximum operating pressure so as to retain the molten residual water.

The operation start procedure also includes a step of providing a humidifier for humidifying the reaction gas flowing through the fuel cell, and a step of providing a water reservoir for supplying water for humidification of the reaction gas stream. The method may include heating the reservoir to melt the water in the reservoir, melting the water in the reservoir, and supplying water to a humidifier for humidifying the gas stream.

Heat for melting the water in the reservoir can be obtained from the fuel processor. The steps for performing the method include operating the fuel processor in an oxidant-rich mode to increase the generated heat, and transferring a portion of the generated heat to the storage to store the fuel in the storage. Melting the water inside, transmitting a part of the generated heat to the fuel cell to raise the fuel cell temperature, monitoring the melting of the water in the reservoir and the fuel cell temperature, Adjusting the reaction mixture in the fuel processor to increase fuel production after at least a portion of the water in the reservoir has been melted and the fuel cell temperature has reached a predetermined temperature.

All of the above structures and operating methods can be used in various combinations. These features, alone or in combination, contribute to the use of fuel cell systems in sub-zero environments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a novel frost-resistant fuel cell structure that is compatible with operation in environments that are exposed to sub-zero temperatures, hereinafter the sub-zero environment. As used throughout this specification, sub-freezing environment also refers to ambient conditions that exceed the freezing point during operation of the fuel cell, but reach the freezing point during periods of fuel cell outage. Preferably, the cooling system and the humidification system are separated. Preferably, the cooling system is also separated from the electrochemically active area of the fuel cell by use of a gasket. Due to the separation of the cooling and humidification systems and the separation of the cooling system from the electrochemically active fuel cell area, substances having a freezing point below the freezing point of water, which would otherwise be detrimental to the fuel cell, It may be used as a coolant substance.
A method of operating a frost-resistant fuel cell in sub-zero conditions is also shown. During start-up of the fuel cell from the idle mode in sub-zero conditions, the fuel cell system is operated in a mode that maximizes the heat generated by the fuel cell. Humidification is delayed until the fuel cell temperature rises above the freezing point. Shutting down a fuel cell in sub-zero conditions involves removing the maximum amount of water from the fuel cell in a minimum amount of time.

A novel frost resistant fuel cell structure having both a gasket and a subgasket is also described. During assembly of the frost-resistant fuel cell, a boundary region is formed between the gasket and the end of the electrochemically active region of the fuel cell. This region is exposed to increased mechanical and electrical stress due to the increased conductivity at the edges as compared to the electrochemically active region of the fuel cell remote from the boundary region. Disclosed is the use of a fuel cell sub-gasket coupled to a gasket to minimize mechanical and electrical stresses at the ends of the electrochemically active fuel cell and provide improved fuel cell reliability. You.

Referring to FIG. A fuel cell is indicated generally by the reference numeral 10. 1
One fuel cell 10 constituted by one cell unit 11 is shown in the figure. However, it is understood that the present invention can be used in connection with a fuel stack having a plurality of cell units. Each battery unit 11 comprises a solid ionic conductive membrane, having an anode 13 on one side of the membrane and a cathode 14 on the other side, each of which is attached directly to the exterior of the membrane. And a membrane electrode assembly (MEA) 12 formed by a suitable catalyst layer. The MEA 12 is sandwiched between the first gas diffusion layer 15 and the second gas diffusion layer 16.

As an alternative, the anode and the cathode may be in close contact with or integral with the gas diffusion layers 15, 16 and are pressed against the membrane. In a preferred embodiment, the ME
A comprises an anode 13 that is more closely adhered to with greater fuel cell efficiency due to its close contact with the electrodes as compared to the pressure contact when the electrodes are mounted on the gas diffusion layers 15,16. It is desirable that the MEA 12 extends a certain minimum distance from the outer circumference on the gas diffusion layers 15 and 16. Alternatively, the ends may be ME
ME only if properly sealed to prevent leakage of reactants around A
A can terminate at the end of the gas diffusion layer. Gas diffusion layer 15, 1
6 is between two conductive collector / separator plates 18, 19 (collector plates) commonly referred to as bipolar plates when more than one fuel cell is used to form the fuel cell stack. It is sandwiched between. The gas diffusion layers 15 and 16 are typically made of a porous conductive material such as carbon / graphite fiber paper or carbon / graphite cloth. When two or more fuel cells form a fuel cell stack, collector plates 18, 19 are provided to separate the cathode of one battery unit 11 from the anode of an adjacent battery unit (not shown). Can be

In a preferred embodiment of the present invention, the fuel cell 10 is a proton exchange membrane (PEM)
It is a fuel cell. Since individual PEM fuel cells produce less than 1 volt at full load, a commercialized PEM fuel cell may require several individual cells, such as cell unit 11, to reach a desired voltage level. Battery 1
One battery is stacked in series by electrically connecting the cathode of the battery to the anode of an adjacent battery (not shown).

The collector plates 18 and 19 have conductivity. In a preferred embodiment of the present invention,
The collector plates 18 and 19 are made of a polymer composite having conductivity by filling a polymer with conductive particles such as graphite. Collector plate 18,
19 may be designed to have a range of high permeability to nearly impervious water permeability. For some applications, it is desirable to have a permeable collector plate. For example, a permeable collector plate may supply water vapor to the fuel cell for humidifying the membrane. However, during operation of the fuel cell, the permeable collector plate stores a significant amount of water. In the application of the fuel cell at a temperature below the freezing point of water, the collector plates 18, 19 which are impermeable to water are prevented in order to avoid damage to the collector plates 18, 19 due to the expansion force exerted by freezing of the contained water. Is generally required. Therefore,
In a preferred embodiment of the present invention, the selected collector plates 18, 19 are substantially impervious to water. At least the surface of the channel may be impermeable to water and the rest of the collector plate may be permeable.

The electrochemical reaction at the cathode 14 that produces water is accompanied by a high degree of exotherm. Therefore, a cooling system is generally needed for fuel cells. To cool the fuel cell,
Deionized water is also commonly used to maintain membrane hydration ("humidification"), which is known to those skilled in the art as necessary for sufficient ion transfer through the membrane. . While this structure is quite sufficient for most fuel cell applications, in applications where the temperature can reach freezing temperatures (less than 0 ° C. at 1 atmosphere), the freezing of water will cause the solids associated with it to freeze. Pure water cannot be used as a coolant because the expansion of the water during the change will damage or destroy the fuel cell.
If necessary, the humidification of the membrane must also be redesigned to avoid freezing of the water in the fuel cell 11. If humidification is required, the present invention separates the humidification system from the coolant system. By separating humidification and cooling, it becomes possible to use a coolant other than pure water. This is important because water freezes at 0 ° C. at 1 atm and it is not possible to use pure water as the coolant in the antifreeze fuel cell.

The humidification of the membrane may be obtained by humidifying the incoming reactant gas from a source external to the fuel cell stack, for example, by using a nebulizer or bubbler. In situations where a fuel processor is used to produce hydrogen fuel, the anode does not require humidification due to the moisture produced as a by-product of the reforming process.

The dedicated coolant loop 25 has a field for coolant to flow through and between the collector plates, which forms a cooling layer adjacent to the fuel cell 11. A conductive sealant 32 binds the top and bottom collector plates. The coolant is
It flows both vertically through the passages and horizontally through the cooling layer to spread the heat evenly over the surface of the collector plate of the adjacent fuel cell 11. A return path for the coolant is provided but not shown.

The coolant loop 25 does not humidify the fuel cell 11. Further, coolant loop 25 is separated from the membrane by a minimum distance "A". Depending on the operating temperature range in which the fuel cell 11 is expected to be exposed, a coolant other than pure water is required as a coolant for the fuel cell 11. Pure water is 0 ° C because water freezes at about 0 ° C at 1 atm.
Not a viable coolant for fuel cell applications that can be During manufacture, the coolant is isolated from the membrane because the coolant system is mechanically sealed. distance"
"A" is selected to avoid contact of the coolant with the membrane and is based on the integrity of the entire fuel cell seal. In a preferred embodiment of the present invention, distance "A" is at least about 0.1 inches. The integrity of the seal is largely a function of the type of gasket material chosen.

[0036] Many coolants other than pure water contaminate fuel cells where they can contact the membrane by occupying catalyst sites. For example, it is known that hydrocarbons occupy catalyst sites. These contaminating coolants are described as "harmful" throughout this specification. Noxious coolants refer to all non-pure water coolants that can be combined with the catalyst when in contact with the MEA electrode or affect the electrochemical reaction of the fuel cell.

In an alternative embodiment of the frost-resistant fuel cell, the coolant passage is not part of the collector plate. For example, the coolant may be flowing through an external manifold adjacent the surface of the fuel cell collector plate. In yet another embodiment of the fuel cell,
The coolant channel is provided in a region of the collector plate surface remote from the fuel cell active region. In both of these alternative embodiments, the coolant does not pass between adjacent collector plates.

Refrigerants other than pure water having a freezing point well below 0 ° C. to match the expected minimum operating temperature of the fuel cell 11 are generally useful for frost-resistant fuel cells. Possible suitable coolants include: (A) Ethylene glycol alone, containing water and / or any concentration of other coolants, including lubricants, as long as the freezing point of the solution is low enough for its intended use. (B) A single propylene glycol containing water and / or any concentration of other coolants, including lubricants, as long as the freezing point of the solution is low enough for its intended use. (C) as long as the freezing point of the solution is low enough for its intended use, it contains water and / or any other cooling agent, including lubricants, and has a freezing point similar to propylene glycol and ethylene glycol And other alcohols having a boiling point, for example methanol. (D) Gas under expected operating conditions, such as nitrogen or hydrogen.

The maximum allowable coolant ionization level depends on the configuration of the coolant loop 25. If the coolant loop 25 is configured to be electrically separated from the collector plates 18, 19, an ionic coolant may be used. However, if the coolant loop 25 is not configured to be electrically isolated from the collector plates 18, 19, the liquid flowing through the coolant loop 25 will cause the adjacent collector plate 18 to be separated.
, 19 (not shown), the coolant ionization level needs to be limited. If the adjacent collector plates 18, 19 (not shown) are at different potentials and are electrically coupled by a coolant loop 25 using a conductive coolant material, the adjacent collector plates 18, 19 Collector plate 18
, 19 (not shown). In a preferred embodiment of the present invention,
If the coolant loop 25 is designed to be electrically isolated from the collector plates 18, 19, the coolant plate and flow field design becomes much more complicated and expensive, so the coolant loop 25 Are not electrically separated from the collector plates 18 and 19.

The separation of the coolant can be provided by a gasket arrangement. MEA1
2 is sandwiched between the first gasket 20 and the second gasket 21. It is desirable that the gaskets 20 and 21 are arranged so as not to overlap the gas diffusion layers 15 and 16. The gaskets 20, 21 may be made of polymeric materials such as EPDM rubber (also known as EP rubber), fluorinated hydrocarbons, butyl rubber, fluorosilicone, polysiloxane, thermoplastic elastomers such as blends containing polypropylene and EP rubber, and And / or consist of other similar substances. A boundary region 22 is formed between the gas diffusion layers 15 and 16 and the gaskets 20 and 21.

The film at or near the boundary region 22 is exposed to both increased mechanical and electrical stress relative to other portions of the active film. If a space is created between the gas diffusion layer 15 and the gas diffusion layer 16 and between the gasket 20 and the gasket 21 during the manufacture of the fuel cell 11, for example, due to a tolerance, the membrane in the boundary region 22 is not supported, May hang down or be pinched. Sagging or pinching results in the inadequate consequence of rupture, which allows reactants to flow from one flow field to another. The intensity of the mechanical stress in the boundary region 22 is reduced by effectively dividing the boundary region 22 into two parts. The boundary region 22 is effectively divided during manufacturing of the fuel cell 11 by moving the upper boundary between the gas diffusion layer 15 and the gasket 20 and the lower boundary between the gas diffusion layer 16 and the gasket 21. You. Also, during manufacture, the gas diffusion layers 15, 16 may be abutted against the gaskets 20, 21, resulting in compression of the membrane in the boundary region 22. In either case, the membrane is exposed to additional mechanical stress in the boundary region, which can result in early life loss of the fuel cell 11.

Further, since it is known that the ends of the parallel conductive plate generate a higher electric flux compared to the inside of the conductive plate, the active film in or near the boundary region 22 has a higher internal flux. When the fuel cell 11 is operated, a higher current density is received. This phenomenon is
A space is formed as shown in FIG. 1, or the gas diffusion layers 15 and 16 are
Enhance the electrical stress on the film in the boundary region, whether or not abutted against 0,21.

Even well-configured frost-resistant fuel cells require special startup, shutdown, and humidification to minimize damage due to ice formation in the frozen state from the water taken inside. I need. In a preferred embodiment of the present invention, all modes of operation of the frost-resistant fuel cell system, such as reactant flow control, temperature monitoring and control, are controlled by a central computer using a feedback control system. Next, reference is made to FIG. To start the fuel cell stack 10, heat from the fuel source is first minimized by the fuel processor 60 through the anode inlet 62 and during operation to minimize the amount of ice formed. With water, the fuel cell 10
Can be supplied to For example, partially oxidized propane based on an automatic thermal fuel processor is placed in the hot gas stream. The hydrogen concentration in the reformed gas stream is set to a desired level by varying the steam to carbon ratio, as well as the air to fuel stoichiometry in the fuel processor 60. High water yields are achieved by feeding the fuel processor 60 with an amount of air close to, or preferably in excess of, that required for complete combustion of the supplied fuel. Thereafter, the hot gas stream generated by the fuel processor 60 is
It is cooled by the coolant therein to cause water condensation, which is separated in the anode separator 68 and sent to the process water tank 64. Combustion is usually a very rapid process, and the fuel processor 60 is operated in this manner until sufficient water has been collected in the process water tank 64. The process water stored in the water tank 64 is used for steam reforming and for humidifying the cathode gas when the operating temperature in the system is above the freezing point of the water. Under start-up conditions in which the process water tank 64 initially contains ice, the fuel processor 60 is operated in the manner of combustion described above, and the hot gas flow generated by the fuel processor 60 generates the frost resistant process water tank 64. Can be used to melt the ice inside. By performing any of the start-up procedures described above, the fuel processor 60 produces a highly hydrogen-rich, high-temperature reactant stream with minimal water content in the fuel cell stack 10 during start-up. The high heat reactant stream facilitates thawing of various fuel stack components.

The humidification needs to be delayed until the temperature of the laminate and the coolant is above the freezing point of the water. During the initial phase of startup, the pressurized dry air is not humidified and the cathode 7
0 is supplied. Pressurized dry air from the cathode compressor typically has a gauge pressure of about 207 kPa (30 kPa) when the temperature of the outside air is in the range of about -10 to -20C.
Heating to a temperature in the range of 90-100 ° C. by pressing at psig). The heated cathode air also facilitates thawing of membranes and other laminate components exposed to freezing conditions. When hydrogen from the fuel processor 60 becomes available for power generation, the fuel cell stack 10 is operated in a low pressure, high current density mode to maximize heat generation. The generated heat is used to raise the temperature of the laminate 10 and the coolant. As the temperature of the stack 10 increases, the stack is activated to begin producing a higher output voltage. Therefore, as the temperature of the fuel cell stack 10 increases, the system is shifted to a more efficient power generation mode. The humidification of the cathode air is started when the temperature of the laminate 10 and the coolant has sufficiently exceeded the freezing point. Optionally, humidification of the anode may also be started simultaneously.

In an alternative embodiment of a frost-resistant fuel cell, the fuel processor shown in FIG. 6 is replaced by a substantially pure hydrogen source. Hydrogen was supplied to the anode together with a supply of oxygen to the cathode, which generated heat immediately. The heat generated raises the temperature of the antifreeze coolant. If the water tank contains ice, the heated antifreeze coolant is circulated through the water tank to melt the ice in the water tank. Once the temperature of the laminate rises above the freezing point of water, humidification of the reactant lines may be initiated.

The method of shutting down the frost-resistant fuel cell also needs to prevent the formation of ice in the fuel cell system at the time of shutting down. In the event of a system outage, the primary purpose is to remove most of the water from the fuel cell stack and system components as quickly as possible. There are three stages required for water removal from the system. First, the system temperature must be reduced to condense the water vapor in the system. The temperature is reduced more rapidly by flowing the coolant through the coolant loop. Cooling of the system allows condensation of the water contained in the gas phase fuel cell. Once the water is in the liquid phase, it can be easily separated from the gas stream and drained to the frost-resistant storage tank 64. Second, the fuel cell stack 10 and system reactant lines need to be totally purged with unhumidified gas, either internally or using an additional purging system. Finally, the entire system must be returned to atmospheric pressure. Following these three-step procedures significantly reduces the amount of condensed water remaining in the fuel cell after shutdown. If water is left in the fuel cell at the time of shutdown, it expands due to freezing and the main fuel cell components, such as anode water separator, cathode water separator, fuel cell stack, fuel processor water storage tank (used ),
And damage to the reactant supply lines.

A similar method for shutting down the anode is described below. If humidification of the anode is used, humidification of the anode gas is stopped. Thereafter, the anode gas line 62 is purged with a dry and low-temperature anode gas. This removes all humidified anode gas from the fuel cell components and removes most of the liquid droplets from the components of the fuel cell system 10.

The condensed water droplets can be separated in one or more anode separators, drained to a frost-resistant storage tank 64, or completely removed from the system. If a process water storage tank is used, the process water storage tank should be located as low as possible to allow gravity to transfer to the water storage tank.

A similar method for shutting down a fuel processor is described below. The temperature of the fuel cell stack is reduced to ambient temperature. An anode cooler / chiller is used to condense moisture from the anode stream and transfer heat to the coolant. This water is removed from the anode stream by the anode separator 74. The separated water can be drained to a frost-resistant storage tank 64 or removed completely from the system. The anode cooler / chiller flows inside the stack and holds a system coolant, which is the temperature of the stack. The laminate temperature is reduced to ambient temperature so that the anode gas temperature can also be cooled to near ambient temperature.

A similar method for shutting down the cathode is described below. Cathode shutdown must be started at the same time as anode shutdown. The humidification of the cathode gas ends. Thereafter, the cathode system is purged with dry cathode gas. The temperature and pressure of the compressor are reduced to near ambient conditions. All liquid water is separated at one or more cathode separators and can be drained to a freeze-resistant water storage tank 64 or completely removed from the system.

A similar method for shutting down the coolant loop is described below. The system layout should be such that the coolant storage tank 76 is located at the lowest point of the system. This allows the coolant to be returned to the coolant storage tank 76 by gravity. The system completes the dry reactant purge at the same time that the coolant is supplied to the coolant storage tank by gravity. Finally, the coolant pump is switched off.

In improving the shutdown process, the fuel cell stack 10 provides a dry reactant to the fuel cell while at the same time generating sufficient current through the stack to generate large amounts of heat. It is operated in the mode that performs. This condition maximizes the rate of water evaporation in the fuel cell stack 10 and results in faster downtime.

The described start-up and shut-down procedures include a number of steps that can be performed in a different order or can be started simultaneously. Please refer to FIG. In a further improvement to the shutdown process, a preferred embodiment of a fuel cell having intricate discontinuous channels in the collector plates 18, 19 is shown. With the flow field anode inlet channel 26, cathode inlet channel 28, anode outlet channel 27, and cathode outlet channel 29 being separated,
The flow through the gas diffusion layer is pumped. The illustrated channel has rounded corners. The involution and rounded corners of the flow field need not necessarily be combined to form a fuel cell improvement for frost-resistant applications. The intricate flow field structure consists of a gas diffusion layer 15,
This promotes the restriction of the amount of water taken into the fuel cell 16 and facilitates the purging of water from the gas diffusion layers 15 and 16 during shutdown of the fuel cell under freezing conditions. In addition, the walls of the channels forming the flow field are slightly tapered, and the rounded corners allow for a place for water to expand during freezing, causing damage to the fuel cell 11 in a frozen state. To minimize.

FIG. 4 adds a set of subgaskets 23 and 24 to the fuel cell having the applicant's gasket shown in FIG. The sub gaskets 23 and 24 are composed of the first and second
Between the gas diffusion layers 15, 16 and the membrane at the distal end of the region where the gas diffusion layers 15, 16 overlap the membrane. The subgaskets 23, 24 provide additional support to the fuel cell at the boundary region to reduce mechanical stress on the membrane at or near the boundary region 22. In addition, the enhanced end conduction across the membrane at the boundary 22 is reduced by moving the active end of the active membrane to the distal ends of the subgaskets 23,24. Thus, the use of subgaskets 23, 24 results in improved fuel cell reliability. In a preferred embodiment of the present invention, the sub-gaskets 23, 24 are made of a strong acid-resistant material, such as FEP, TFE, ETFE, PFA, CTFE, E-CTFE, PV.
F _2, and is formed from a PVF, has about one-tenth the thickness of the thickness of the gasket 20, 21.

As shown, the coolant loop 25 passes through the gaskets 20, 21 as well as the sub-gaskets 23, 24. As described above, the sub gasket 23
, 24 reduce mechanical and electrical stresses near the edge of the active film in the boundary region 22. The subgaskets 23, 24 do not necessarily have to extend the same end and end of the main gaskets 20, 21 on the opposite side of the active membrane. In a preferred embodiment of the invention, the subgaskets 23, 24 are added for ease of manufacture and for forming relatively short subgaskets 23, 24 that do not extend significantly outside the active membrane area. Sub-gaskets 23, 24
Due to the relatively low material cost, they are terminated with the main gaskets 20, 21 on the opposite side of the active membrane.

While the preferred embodiments of the invention have been illustrated and described, it will be clear that the invention is not so limited. Numerous improvements, changes, alternatives, permutations, and equivalents will occur to those skilled in the art without departing from the spirit and scope of the invention as set forth in the claims.

[Brief description of the drawings]

FIG. 1 is a cut-away side view of a fuel cell and coolant system according to the invention.

FIG. 2 shows a fuel cell stack connected to a fuel processor and an external cooling and humidification system, which is used to carry out the method of the present invention using a freeze-resistant fuel cell. Schematic.

FIG. 3 is a side view of a fuel cell having a collector plate with a discontinuous flow field channel having tapered and rounded corners.

FIG. 4 is a cut-away side view of a fuel cell having a first gasket and a second sub-gasket.

[Procedural Amendment] Submission of translation of Article 34 Amendment

[Submission date] April 5, 2001 (2001.4.5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Contents of correction]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0003

[Correction method] Change

[Contents of correction]

(1) H ₂ → 2H ⁺ + 2e ⁻ anode reaction Protons are drawn into the fuel cell electrolyte. The generated electrons travel from the anode of the fuel cell to the anode terminal, and return to the cathode terminal and back to the cell cathode by electrical loading. The flow of ions through the electrolyte completes the circuit. Chemical reaction rates vary with location on the electrode and depend on local factors such as the concentrations of reactants and product products, and temperature. As shown in equation (2), at the cathode , oxygen combines with electrons from the load and protons from the electrolyte to form water.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Contents of correction]

Yet another object of the present invention is to provide a technique for removing water from a fuel cell when operation is stopped and rapidly reheating the fuel cell when operation is started. These and other objects of the invention are achieved by a number of embodiments that embody the features and advantages of the invention. The present invention may have a freeze-tolerant fuel cell system comprising at least one fuel cell formed from a pair of collector plates having a series of channels for a reactant stream. A first gas diffusion layer and a second gas diffusion layer are disposed between the collector plates, and the membrane electrode assembly (MEA) includes a membrane sandwiched between the two electrode layers. An MEA disposed between the gas diffusion layers;
The reactants on each side of the MEA are substantially sealed from leaking to the other side of the MEA. The fuel cell stack further comprises at least one coolant flow path for flowing a coolant flow to the collector plate such that the coolant flow does not contact the MEA while cooling the fuel cell.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Contents of correction]

According to another aspect of the present invention, the coolant flowing through the cold却剤passage are the harmful to MEA, thus must be physically isolated from the MEA. The surface of the coolant channel in contact with the coolant may be electrically insulated, or the coolant may be non-conductive. Said isolation may be provided by providing a gasket device around a coolant port extending through the collector plate. The gasket is preferably spaced from the gas diffusion layer. Alternatively, the cooling passage can be located outside the conductive part of the collector plate and be surrounded by the housing. The housing may be integrally formed with the collector plate or connected to the collector plate.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Contents of correction]

[0012] The fuel cell coolant loop provides edge cooing within the fuel cell.
or including ling), there have may coolant layer is provided on the outside of the collector plate. This coolant layer is provided immediately adjacent to each reactive fuel cell or in intermittent steps throughout the fuel cell stack.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Contents of correction]

In order to protect against mechanical damage of the collector plate due to freezing expansion of the remaining water, the walls of the channels may be tapered and have rounded corners. According to the present invention, the fuel cell system can become more resistant to freezing by incorporating an operation stop procedure that contributes to the freezing environment. The operation stop procedure, humidification by reducing the fuel cell system temperature, a step of condensing the fuel stack steam, water from the fuel cell, a liquid, and removing the gas, the reaction gas line Purging with unpurified gas and reducing the system pressure to a pressure approximately equal to atmospheric pressure may be included. These steps may be performed in a different order, or alternatively, may be started simultaneously.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Contents of correction]

The shutdown procedure may include a step of further increasing the heat of the fuel cell at or immediately prior to shutdown. One preferred process involves causing operated in a mode that produces a pulsed current output fuel stack.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0022

[Correction method] Change

[Contents of correction]

During start-up, the presence of significant amounts of water before the fuel is heated above its freezing point can present a risk of damage due to freezing and expansion of the water. Thus, the technique according to the invention comprises a start-up procedure for introducing water so as to prevent freezing. These techniques, the step of flowing a dried reaction gas through the reaction line to the fuel cell, a step of measuring the temperature of the fuel cell, reaction after the fuel cell temperature is higher than a predetermined temperature Starting the humidification of the gas. The predetermined temperature can be the freezing point of water at atmospheric pressure. The start-up procedure may preferably include the step of increasing the heat of the fuel cell and pressurizing to a maximum operating pressure so as to retain the molten residual water.

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0024

[Correction method] Change

[Contents of correction]

Heat for melting the water in the reservoir can be obtained from the fuel processor. Process for carrying out the method, in order to increase the heat generated, a step of operating the fuel processor in oxidizing agent excess mode, the reservoir and transfer some of the heat that occurred savings built instrument a step of melting the water inside, a step of raising the fuel cell temperature by transferring some of the heat that occurred fuel cell, comprising the steps of monitoring the melting and the fuel cell temperature of the water savings built device,
Adjusting the reaction mixture in the fuel processor to increase fuel production after at least a portion of the water in the reservoir has been melted and the fuel cell temperature has reached a predetermined temperature.

[Procedure amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0029

[Correction method] Change

[Contents of correction]

As an alternative, the anode and the cathode may be in close contact with or integral with the gas diffusion layers 15, 16 and are pressed against the membrane. In a preferred embodiment, the ME
A comprises an anode 13 that is more closely adhered to with greater fuel cell efficiency due to its close contact with the electrodes as compared to the pressure contact when the electrodes are mounted on the gas diffusion layers 15,16. It is desirable that the MEA 12 extends a certain minimum distance from the outer circumference on the gas diffusion layers 15 and 16. As an alternative, each end may be M
Only if properly sealed to prevent leakage of reactants around the EA
The EA can terminate at the end of the gas diffusion layer. Gas diffusion layer 15,
16 is between two electrically conductive collector / separator plates 18, 19 (collector plates) commonly referred to as bipolar plates when more than one fuel cell is used to form the fuel cell stack. It is sandwiched between. The gas diffusion layers 15 and 16 are typically made of a porous conductive material such as carbon / graphite fiber paper or carbon / graphite cloth. When two or more fuel cells form a fuel cell stack, collector plates 18, 19 are provided to separate the cathode of one battery unit 11 from the anode of an adjacent battery unit (not shown). Can be

[Procedure amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Contents of correction]

Even well-configured frost-resistant fuel cells require special startup, shutdown, and humidification to minimize damage due to ice formation in the frozen state from the water taken inside. I need. In a preferred embodiment of the present invention, all modes of operation of the frost-resistant fuel cell system, such as reactant flow control, temperature monitoring and control, are controlled by a central computer using a feedback control system. Next, reference is made to FIG. To start the fuel cell stack 10, heat from the fuel source is first minimized by the fuel processor 60 through the anode inlet 62 and during operation to minimize the amount of ice formed. With water, the fuel cell 10
Can be supplied to For example, partial oxidation based on the autothermal fuel processor for converting a hydrocarbon such as propane in the hot gas stream. The hydrogen concentration in the reformed gas stream is set to a desired level by varying the steam to carbon ratio, as well as the air to fuel stoichiometry in the fuel processor 60. The high water yields can result in an amount of air close to, or preferably in excess of, that required for complete combustion of the supplied fuel,
This is achieved by supplying Thereafter, the hot gas stream generated by the fuel processor 60 is cooled by the coolant in the anode 66 to cause water condensation, which is separated in the anode separator 68 and sent to the process water tank 64. Combustion is usually a very rapid process, and the fuel processor 60 is operated in this manner until sufficient water has been collected in the process water tank 64. The process water stored in the water tank 64 is used for steam reforming and for humidifying the cathode gas when the operating temperature in the system is above the freezing point of the water. Under start-up conditions in which the process water tank 64 initially contains ice, the fuel processor 60 is operated in the manner of combustion described above, and the hot gas flow generated by the fuel processor 60 generates the frost resistant process water tank 64. Can be used to melt the ice inside. By performing any of the start-up procedures described above, the fuel processor 60 produces a highly hydrogen-rich, high-temperature reactant stream with minimal water content in the fuel cell stack 10 during start-up. The high heat reactant stream facilitates thawing of various fuel stack components.

[Procedure amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0045

[Correction method] Change

[Contents of correction]

In an alternative embodiment of a frost-resistant fuel cell, the fuel processor shown in FIG. 2 is replaced by a substantially pure hydrogen source. Hydrogen was supplied to the anode together with a supply of oxygen to the cathode, which generated heat immediately. The heat generated raises the temperature of the antifreeze coolant. If the water tank contains ice, the heated antifreeze coolant is circulated through the water tank to melt the ice in the water tank. Once the temperature of the laminate rises above the freezing point of water, humidification of the reactant lines may be initiated.

[Procedure amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0055

[Correction method] Change

[Contents of correction]

A coolant loop similar to the cooling loop 25 shown in FIG .
It passes through gaskets 20, 21 as well as 3, 24. As described above, the subgaskets 23, 24 reduce the mechanical and electrical stresses near the edge of the active film in the boundary region 22. The subgaskets 23, 24 do not necessarily have to extend the same end and end of the main gaskets 20, 21 on the opposite side of the active membrane. In a preferred embodiment of the invention, the subgaskets 23, 24 are added for ease of manufacture and for forming relatively short subgaskets 23, 24 that do not extend significantly outside the active membrane area. Because the material costs of the subgaskets 23, 24 are relatively low compared to the labor costs of the subgaskets 23, 24, they end with the main gaskets 20, 21 on the opposite side of the active membrane.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01M 8/10 H01M 8/10 8/24 8/24 E // H01M 8/00 8/00 Z (81 ) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OA (BF, BJ, CF) , CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW) ), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR , CU , CZ, DE, DK, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, L K, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, UZ, VN, YU, ZA, ZW (72) Inventor Barbie, Furano USA 33410 Palm Beach Gardens, Aspen Way 10163 (72) Inventor Gu, Yang United States 33407 West Palm Beach, Florida Thirty First Street 521 (72) Inventor Hussar, Attila United States 33401 West Palm Beach, Florida Executive Center Interdrive 701 Number 1015 (72) Inventor Snipas, Rachel United States 33408 Juno Beach, Florida South Lyra Circle 440 F-term (reference) 5H026 AA06 CC03 5H027 AA06 BA01 CC06 CC11 DD00 MM16 MM21

Claims (45)

 [Claims] 1. An anti-freeze fuel cell system comprising at least one fuel cell, wherein the at least one fuel cell system is a pair of collector plates, and receives a signal from a port formed through the collector plates. A membrane electrode assembly comprising: a collector plate having a series of channels for reactant flow; a first gas diffusion layer and a second gas diffusion layer disposed between the collector plates; and a membrane sandwiched between two electrode layers. (MEA), the MEA being disposed between the gas diffusion layers, and a seal provided to substantially prevent the movement of reactants around the MEA. The battery system further comprises at least one coolant flow path for flowing a coolant flow to the collector plate to cool the fuel cell, wherein the coolant flow is The fuel cell system that is not in contact with the serial MEA. 2. The fuel cell system according to claim 1, further comprising a coolant flowing in the coolant channel, wherein the coolant is harmful to the MEA. 3. The fuel cell system according to claim 1, wherein a surface of the coolant passage in contact with the coolant is electrically insulated. 4. The fuel cell system according to claim 1, wherein the coolant is non-electric. 5. The fuel cell system according to claim 1, further comprising a coolant loop, wherein the at least one coolant channel forms a part of the coolant loop. 6. The fuel cell system according to claim 5, wherein the coolant loop comprises a coolant layer outside the collector plate. 7. The fuel cell system according to claim 6, wherein said coolant layer is adjacent to one of said collector plates. 8. The fuel cell system according to claim 5, wherein the coolant loop comprises a plurality of coolant channels in the collector plate separated from the reactant channels. 9. The collector plate comprising a plurality of coolant ports separated from the reactant stream for coolant transfer, surrounding the coolant ports and disposed between the collector plates. The fuel cell system according to claim 1, further comprising a gasket. 10. The fuel cell system according to claim 1, wherein the coolant channel is accommodated in a structure outside a conductive region of the collector plate. 11. The fuel cell system according to claim 9, wherein the pair of gaskets are separated from the gas diffusion layer. 12. The fuel cell system according to claim 9, wherein at least the membrane extends over at least a part of a periphery of the gas diffusion layer, and a pair of gaskets overlap the membrane. 13. The apparatus further comprises a pair of subgaskets, each subgasket being disposed between the gaskets and extending to a location between the gas diffusion layer and the MEA to support the membrane. The fuel cell system according to claim 9. 14. The fuel cell system according to claim 13, wherein the sub gasket is formed from a fluorine-based polymer. 15. The sub gasket is made of FEP, TFE, ETFE, PF
The fuel cell system according to claim 14, wherein the fuel cell system is formed from a material selected from A, CTFE, E-CTFE, PVF2 _, and PVF. 16. The fuel cell system according to claim 1, wherein the fuel cell is a proton exchange membrane (PEM) fuel cell, and the ion exchange membrane is permeable. 17. The fuel cell system according to claim 1, wherein the discontinuity of the reactant channel establishes a reactant gas flow through a gas diffusion layer. 18. The reactant channels in each collector plate are configured such that the direction of the reactant stream in one gas diffusion layer is opposite the direction of the reactant stream in the gas diffusion layer opposite the MEA. 18. The fuel cell system according to claim 17, whereby a large water gradient is established to facilitate water movement during shutdown and purge operations. 19. The reactant channel in each collector plate, wherein a relatively dry portion of the reactant on one side of the MEA faces a relatively wet portion of the reactant on the other side of the MEA. 18. The fuel cell system of claim 17, wherein the fuel cell system is configured to establish a large water gradient to facilitate water movement during shutdown and purge operations. 20. The fuel cell system according to claim 1, wherein the surface of the channel is essentially impermeable to water. 21. The fuel cell system according to claim 20, wherein the surface of the channel is essentially impermeable to all fluids. 22. The wall of the channel is tapered and has rounded corners, so that the remaining water in the frozen fuel cell can freely expand and prevent damage to the collector plate. The fuel cell system according to claim 1, wherein 23. The method of claim 1, wherein the reactant channel has a plurality of reactant outlets, wherein at least one of the outlets is located below the channel such that water removal is assisted by gravity. Fuel cell system. 24. A water reservoir disposed outside the stack, wherein the reactant channels actuate a reactant outlet to the water reservoir to drain water from the fuel cell to the water reservoir. The fuel cell system according to claim 1, wherein the fuel cell system is electrically connected. 25. The fuel cell system according to claim 24, wherein the water reservoir is freezing resistant and comprises at least one isolation and heating source. 26. The fuel cell system according to claim 25, wherein the heating source is a storage heater. 27. The fuel cell system according to claim 25, wherein the heating source is a fuel processor. 28. The fuel cell system according to claim 25, wherein the heating source is a fuel cell. 29. A method of using a fuel cell system in an environment that is below freezing temperature, wherein the fuel cell system has at least one fuel cell,
The fuel cell comprises a membrane, a pair of gas diffusion layers, a pair of electrodes, a pair of collector plates, and at least two reactant flow lines, wherein the method comprises: Forming at least one coolant flow path to the fuel cell to prevent contact with a membrane; and flowing a harmful coolant flow through the membrane through the at least one flow path,
The coolant stream does not contact the membrane such that it is possible to use a coolant having a freezing point lower than the freezing point of water. 30. The method according to claim 29, wherein said coolant substance is a fluoropolymer. 31. A method for shutting down a fuel cell system in an environment at a temperature below freezing, wherein the fuel cell system includes a membrane, a pair of gas diffusion layers, a pair of electrodes, and a pair of collector plates. Comprising at least one fuel cell having at least two reactant flow lines, wherein water vapor in the fuel cell is condensed by lowering a fuel cell system temperature; and water, liquid, and A method comprising: removing a gas; purging at least one reactant gas line with a non-humidified gas; and reducing a system pressure to a pressure approximately equal to atmospheric pressure. 32. The method of claim 31, wherein removing water comprises purging from the system. 33. The method of claim 31, wherein removing the water comprises discharging the water to a water reservoir. 34. The method of claim 31, wherein said shutting down further comprises: operating said fuel stack in a mode that produces a pulsed current output. 35. A method for starting operation of a fuel cell system in an environment at a temperature below freezing, wherein the fuel cell system includes a membrane, a pair of gas diffusion layers, a pair of electrodes, and a pair of collector plates. Flowing at least one fuel cell having at least two reactant flow lines into the fuel cell through the at least one reactant line; and controlling the temperature of the fuel cell. A method comprising: measuring; and starting humidification of the reaction gas after the fuel cell temperature becomes higher than a predetermined temperature. 36. The method of claim 35, wherein said predetermined temperature is the freezing point of water at atmospheric pressure. 37. Preparing a humidifier for humidifying the reaction gas flowing through the fuel cell stack, providing a reservoir for supplying water for humidifying the reaction gas flow, and storage. 37. The method of claim 36, further comprising: heating the reservoir to melt the water in the vessel; melting the water in the reservoir; and supplying water to a humidifier for humidifying the gas stream. Method. 38. The step of heating the reservoir, operating the fuel processor in an oxidant-rich mode to increase the heat generated, and generating the heat to melt the water in the reservoir. Transferring a portion of the generated heat to the fuel cell to increase the temperature of the fuel cell; and melting the water in the reservoir and the fuel cell temperature to increase the temperature of the fuel cell. And adjusting the reaction mixture in the fuel processor to increase fuel production after at least a portion of the water in the reservoir has been melted and the fuel cell temperature has reached a predetermined temperature. 32. The method of claim 31, comprising: 39. A method of using a proton exchange membrane (PEM) fuel cell stack in a sub-zero environment, the fuel cell stack each comprising a membrane and a pair of gas diffusion layers at a temperature below the freezing point of water. Layer, a pair of electrodes, a pair of collector plates, and a plurality of fuel cells including at least a pair of gaskets, passing between the pair of collector plates and between the pair of gaskets of each of the fuel cells, And not passing through the membrane, forming at least one flow path, and flowing a coolant flow harmful to the membrane through the at least one flow path, so that the coolant flow does not contact the membrane, Flowing a dry reactant gas into the fuel cell through the at least two reactant lines; measuring a temperature of the fuel stack; Starting the humidification of the reaction gas after the temperature is exceeded; reducing the temperature of the fuel cell system; and purging the reaction gas line with one or more non-humidified gases. And a shutdown step for reducing the pressure of the system to a pressure approximately equal to atmospheric pressure. 40. The method of using a proton exchange membrane (PEM) fuel cell stack according to claim 39, wherein the operation stopping step further includes a step of operating the fuel stack in a mode that generates a pulse current output. 41. A fuel cell stack comprising at least one fuel cell with a gasket, the at least one fuel cell with a gasket each having a sheet of conductive material and a pair of oppositely facing flat surfaces. A first gas diffusion layer and a second gas diffusion layer, the gas diffusion layers being disposed substantially parallel to each other, a membrane electrode assembly (MEA) disposed between the gas diffusion layers, and the MEA
Has a pair of opposite surfaces, an ion exchange membrane, and a pair of electrodes disposed between the ion exchange membrane and the gas diffusion layer; The gasket, the pair of gaskets, the MEA being inserted between the ends of the gasket, the gasket not overlapping the gas diffusion layer, where the boundary is A fuel cell stack comprising: being formed; wherein the gas diffusion layer, the gasket and the MEA are all inserted between a pair of collector plates; and wherein the collector plates are provided with channels for reactant flow. . 42. The fuel cell stack according to claim 41, wherein said fuel cell is a proton exchange membrane (PEM) fuel cell and said ion exchange membrane is water permeable. 43. The fuel cell stack according to claim 42, wherein the surface of the channel is essentially impermeable to fluid. 44. The apparatus further comprising a pair of subgaskets, each subgasket being disposed between the gaskets, and between the gas diffusion layer and the MEA at an end of a region where the gas diffusion layer overlaps the MEA. 44. The fuel cell stack of claim 43, wherein the fuel cell stack extends to a location, thereby supporting the membrane boundary region. 45. The sub gasket is made of FEP, FTE, ETFE, PFA.
, CTFE, E-CTFE, fuel cell according to claim 44, which is formed from a material selected from the group consisting of PVF _2, and PVF.