JP2004220857A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small fuel cell suppressing the crossover of fuel and enhancing fuel utilization efficiency by supplying fuel to an electrode according to the amount of reaction without using electric power. <P>SOLUTION: The volume contraction of a fuel storage tank is produced by operating a partition separating the fuel storage tank and a gas chamber by gas pressure inside the gas chamber, and the amount of fuel supplying to the electrode through a fuel supply passage is made variable. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell used as a power source for a small electronic device such as a mobile phone or a notebook computer.
[0002]
[Prior art]
A fuel cell is a device that electrochemically generates hydrogen ions at the anode and reduces oxygen at the cathode, and obtains an output from the potential difference between the electrodes and the current taken out by the electrochemical reaction. The fuel cell has an advantage that the conversion efficiency to electric energy is higher than that of other power supply devices, and the reaction product does not contain sulfide or nitride. In addition, when a fuel cell is driven, waste heat and gaseous reaction products and by-products are generated. This waste heat should be used as an energy source for operations necessary to drive the fuel cell. (For example, refer to Patent Document 1). However, the present situation is that the gaseous products are discarded.
[0003]
Of the fuel cells, a solid polymer type is often used for consumer use. In a polymer electrolyte fuel cell, it is common to use hydrogen as a fuel at the anode. In this case, a tank for storing hydrogen or a reformer for reforming other fuel into hydrogen is required. Here, in order to improve the energy density, it is necessary to make the tank extremely high in pressure, and the size becomes large. Further, due to the presence of the reformer, the overall dimensions must be increased.
[0004]
On the other hand, there is a direct fuel cell that generates electric power by directly contacting a liquid fuel with an electrode as a fuel cell capable of reducing the size. In this format, alcohols typified by methanol and ethanol, ethers, ketones, inorganic hydrides and the like are used as fuel. In these fuels, carbon dioxide is generated on the electrode or hydrogen is by-produced. In this fuel cell, since the liquid fuel is present in the vicinity of the electrode as a liquid, it can be in a power generation state without using a reformer, and does not require a high pressure to hold the fuel. Therefore, it is a dimensionally advantageous system for small fuel cells.
[0005]
[Patent Document 1]
Japanese Patent No. 3352716 (page 3-6, Fig. 1)
[0006]
[Problems to be solved by the invention]
However, the direct fuel cell has a problem in that a liquid fuel directly contacts the electrolyte, so that a crossover through which the fuel passes through the electrolyte is unavoidable. Crossover leads to a small potential difference between the positive electrode and the negative electrode, and wasteful discharge of fuel. In order to increase the fuel utilization rate and obtain an effective output, the crossover amount must be reduced as much as possible. The crossover amount increases as the fuel volume increases and the concentration increases. In order to reduce the volume of the fuel that is in direct contact with the electrolyte, it is only necessary to mechanically efficiently deliver the fuel. However, when a fuel cell is applied to portable and mobile electronic devices, the size of the fuel cell becomes extremely small, making it difficult to incorporate a fuel feed mechanism having a large size.
[0007]
Further, in the fuel feed mechanism that performs electrical control, electric power is used for the control monitor and the drive mechanism drive device. If the electric power is supplied by the fuel cell, the utilization efficiency of the output used to drive the electronic device is lowered. This is very disadvantageous because when the fuel cell is downsized, the effective fuel utilization efficiency is lowered.
[0008]
An object of the present invention is to solve the above problems, and to provide a fuel cell that is small and has high fuel utilization efficiency.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the fuel cell of the present invention is configured to include a fuel supply mechanism for supplying fuel from a fuel storage to the electrode using gas generated at the electrode. This makes it possible to effectively use products that have only been discarded. In other words, the surplus energy that was discarded is used for supplying fuel without using power. This leads to an improvement in fuel utilization efficiency.
[0010]
Further, a solid polymer electrolyte was used for the fuel cell. Thereby, the pressure of the generated gas can be maintained, and it becomes easy to secure surplus energy.
[0011]
The fuel cell includes an electrolyte, an electrode, a gas chamber that collects gas generated on the electrode, a fuel storage, a fuel supply passage that supplies an appropriate amount of fuel from the fuel storage to the electrode, a gas chamber, and a fuel storage And the whole partition wall or a part of the partition wall is movable.
[0012]
Thereby, the influence of the generated gas can be exerted on the fuel storage.
[0013]
The entire partition wall or a part of the partition wall is operated by the gas pressure in the gas chamber, causing volume contraction of the fuel storage, and the amount of fuel supplied to the electrode through the fuel supply path is variable.
[0014]
Thereby, according to the production amount of the gas produced | generated on the electrode, a fuel will be supplied to an electrode from a fuel storage. Conversely, if no gas is generated on the electrode, no fuel is supplied to the electrode. Therefore, the amount of fuel existing in the vicinity of the electrode can be suppressed within the required range, and the fuel crossover can be reduced.
[0015]
Specifically, the partition wall includes a movable part and a fixed part, and the movable part is a plunger that operates while contacting the fixed part.
[0016]
Thus, fuel is supplied from the fuel storage to the electrode according to the amount of movement of the movable part in response to the pressure of the gas chamber.
[0017]
Furthermore, the fuel supply path is formed in the plunger.
[0018]
As a result, there is no need to provide a fuel supply path at the fixed portion of the partition wall.
[0019]
Alternatively, the partition wall is made of a material that can be easily deformed by gas pressure in the gas chamber and cause volume contraction of the fuel storage.
[0020]
As a result, the volume of the fuel storage can be changed without providing a structure that moves under the pressure of the gas chamber.
[0021]
The fuel cell includes an electrolyte, an electrode, a gas chamber for collecting gas generated on the electrode, a fuel storage, a fuel supply path for supplying fuel from the fuel storage to the electrode in an appropriate amount, a gas chamber, A partition that separates the fuel storage, a pump provided in the fuel supply path, a mechanism that operates the pump, and a gas discharge valve that discharges gas from the gas chamber, and the pump is driven by the gas generated on the electrode It is characterized by that.
[0022]
Accordingly, an appropriate amount of fuel can be supplied to the electrode by a pump driven by surplus energy. Fuel utilization efficiency can be improved.
[0023]
The pump is operated through a mechanism that operates the pump by the pressure of gas generated on the electrode, and the amount of fuel supplied to the electrode through the fuel supply path is variable.
[0024]
Thereby, according to the production amount of the gas produced | generated on the electrode, a fuel will be supplied to an electrode from a fuel storage. Conversely, if no gas is generated on the electrode, no fuel is supplied to the electrode. Therefore, the amount of fuel existing in the vicinity of the electrode can be suppressed within a necessary range, and the crossover of fuel can be reduced. Moreover, since the driving force source of the pump is surplus energy, ie, the pressure of the generated gas, and not electric power, the fuel can be effectively used for small electronic devices. In addition, the mechanism can be reduced to a volume that can be incorporated into a fuel cell for a small electronic device.
[0025]
Specifically, the pump is driven by gas passing through the gas discharge valve.
[0026]
Thereby, since the pressure in the gas storage chamber can be made constant, a high pressure-resistant structure is not required, and the structure of the fuel cell exterior can be simplified.
[0027]
Further, as a mechanism for operating the pump, a rotor that rotates when gas passes from the gas discharge valve is provided.
[0028]
Thus, the rotor can be rotated as the gas flows out of the gas chamber, and the kinetic energy of the gas can be efficiently converted into rotational energy.
[0029]
In addition, the mechanism for operating the pump is characterized in that it is arranged at the gas discharge valve and the location from the gas discharge valve to the pump.
[0030]
Thereby, the rotational energy obtained by the rotor can be transmitted to the pump.
[0031]
Specifically, a gear train mechanism for transmitting the rotation of the rotor to the pump is provided at a location from the rotor to the pump.
[0032]
As a result, the rotational energy of the rotor can be reliably transmitted to the pump, and the pressure of the generated gas can be effectively used for driving the pump.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
The fuel cell of the present invention includes a fuel supply mechanism that supplies gas from the fuel storage to the electrode using gas generated at the electrode. In addition, it has a gas chamber that collects gas generated at the electrode and a fuel storage that stores fuel for power generation, and applies pressure to the fuel stored in the fuel supply storage using the change in the amount of gas stored in the gas chamber Therefore, the fuel was supplied from the fuel storage to the electrode. Also, a gas chamber for collecting gas generated at the electrode and a fuel storage for storing fuel for power generation are provided, and the volume of the fuel supply storage is changed according to the pressure change of the gas chamber, so that the fuel storage can be changed from the electrode to the electrode. It was decided to supply fuel. A gas chamber for collecting gas generated by the electrode; a fuel storage for storing fuel for power generation; a partition wall provided between the gas chamber and the fuel storage; movable by pressure received from the gas chamber; and a fuel storage A fuel supply passage for supplying fuel to the electrode is provided, and the fuel in the fuel storage is supplied to the electrode in accordance with the movement of the partition wall. In addition, a fuel storage for storing fuel for power generation and a pump driven by gas generated at the electrode are provided, and fuel is supplied from the fuel storage to the electrode using the pump.
[0034]
With such a configuration, it becomes possible to supply fuel to the electrode according to the reaction amount in the power generation portion. Therefore, it is possible to suppress a fuel crossover, to realize a small-sized fuel cell with high fuel utilization efficiency, and to supply appropriate fuel to the electrode without using electric power.
[0035]
Further, the fuel is supplied to the electrode through a diffusion layer that holds the fuel. Thereby, only the fuel held in the diffusion layer comes into contact with the electrode. That is, the reactant that crosses over is only the fuel retained in the diffusion layer, and it is possible to suppress a decrease in voltage and a decrease in the amount of reactant during long-term storage.
[0036]
【Example】
Example 1
A cross-sectional configuration of the fuel cell of this example is schematically shown in FIG. The fuel cell of this embodiment includes a power generation part, a fuel supply part, and a gas flow path. Specifically, the power generation portion is configured such that the solid electrolyte 1 is sandwiched between the anode electrode 2 and the cathode electrode 3. The fuel supply part includes a fuel storage 4, a fuel supply path 5 for sending fuel from the fuel storage 4 to the power generation part, and an anode electrode 2 and a fuel supply for evenly dispersing the anode electrode 2 while holding the fuel. It comprises a diffusion layer 6 disposed in contact with the outlet of the passage 5 and a valve 7 provided in the fuel supply passage 5 so that fuel does not flow except during fuel supply. The gas flow path includes a gas chamber 8 in which gas generated by the reaction of fuel at the anode electrode 2 is present, and a gas discharge valve 9 that discharges the generated gas to the outside of the fuel cell. The fuel storage 4 and the gas chamber 8 are separated by a partition wall 10.
[0037]
The fuel stored in the fuel storage 4 is sent to the diffusion layer 6 through the fuel supply path 5. When a load is applied to the anode electrode 2 and the cathode electrode 3 from the electric circuit, the fuel reacts on the anode electrode 2 to generate mainly hydrogen ions, gas, and electrons. Electrons are supplied to the electric circuit, and hydrogen ions pass through the solid electrolyte 1 and are supplied to the cathode electrode 3. In the cathode electrode 3, hydrogen ions, electrons supplied from an electric circuit, and a reducible oxide represented by oxygen react to be consumed.
[0038]
As an example of the fuel, an alcohol or ether, specifically, an aqueous solution containing at least one of methanol, ethanol, propanol, butanol, ethylene glycol, glycerin, dimethyl ether and the like is used. For the anode electrode 2, platinum, ruthenium, palladium, gold, silver, nickel, iron or the like is used. Preferably, platinum is used. The gas generated by the electrode reaction is mainly carbon dioxide.
[0039]
In the present fuel cell, the partition wall 10 is provided so as to be movable. Therefore, when the gas generated when a load is applied to the power generation portion stays in the gas chamber 8 and the pressure of the gas chamber increases, the partition wall 10 moves in a direction in which the volume of the fuel storage 4 is contracted. As a result, the fuel is supplied to the diffusion layer 6 through the fuel supply path, and the fuel is sent to the anode electrode 2. The greater the load applied to the power generation part, the more gas is generated and the pressure in the gas chamber increases. Therefore, the load applied to the partition wall 10 is large, the compression of the fuel storage 4 is increased, and a lot of fuel is sent to the diffusion layer side. Here, the pressure of the gas chamber can be controlled by the gas discharge valve 9. On the other hand, if the load is small, the amount of gas generated decreases, so the amount of fuel sent to the anode electrode 2 decreases.
[0040]
At the beginning of using the fuel cell, the fuel can be sent to the diffusion layer 6 through the fuel supply path 5 by the pressure at which the fuel is stored in the fuel storage 4. Therefore, at the beginning of use of the fuel cell, the fuel is held in the diffusion layer 6 and is in contact with the anode electrode 2.
[0041]
Moreover, in this structure, in order to prevent the gas in the gas chamber from entering the fuel chamber 4, sealing is provided between the movable partition wall 10 and the surrounding fixed portion. Resin, rubber, or the like can be used for sealing.
[0042]
The fuel reactant sent to the anode electrode 2 crosses over the solid electrolyte 1 and reaches the cathode electrode 3, which causes serious problems such as a decrease in voltage and a decrease in reactants. In the conventional configuration, since the amount of fuel sent to the anode electrode 2 is not limited, all the fuels held in the fuel cell may cross over. In particular, when the fuel cell is stored for a long time, the crossed-over fuel evaporates from the cathode electrode 3, so that a crossover always occurs and the amount of reactants is extremely reduced.
[0043]
However, in the present fuel cell, only the fuel held in the diffusion layer 6 is in contact with the anode electrode 2 by the above configuration. Therefore, the reactant that crosses over is only the fuel held in the diffusion layer 6, and the fuel in the fuel storage 4 does not cross over. Accordingly, it is possible to suppress a decrease in voltage and a decrease in the amount of reactant during long-term storage.
[0044]
(Example 2)
In this embodiment, an aqueous solution of inorganic chemical hydride is used as the fuel. More specifically, it is one of the group consisting of lithium, sodium, potassium, magnesium borohydride or aluminum halide. The structure of the fuel cell is similar to that of the first embodiment, and there are cases where a material other than platinum is used for the anode electrode 2.
[0045]
In the fuel cell of this example, the product at the electrode is hydrogen. Hydrogen generation is not limited to an electrochemical reaction, but may be hydrolysis or thermal decomposition. That is, the generated hydrogen includes a by-product generated on the anode electrode 2 by a reaction mechanism different from the power generation reaction of the fuel cell.
[0046]
Regarding the above-mentioned fuel, there are a problem of crossover, such as a decrease in voltage and a loss of fuel. The fuel that has crossed over reacts at the cathode electrode 3 to generate hydrogen, leading to a reduction in the amount of fuel in the anode electrode 2.
[0047]
(Example 3)
FIG. 2 is a cross-sectional view of the fuel cell of this example. In the fuel cell of this embodiment, the working part and the fixed part are configured in the partition wall 10 of the first example, and the plunger 11 that operates while contacting the working part with the fixed part is used.
[0048]
In this embodiment, since the fuel supply path 5 and the plunger 11 are configured in different parts, the sealing structure between the plunger 11 and the fixed part of the partition wall 10 becomes simple. Therefore, in addition to the effect of the first embodiment, there is an effect that an airtight structure is easily obtained.
[0049]
Example 4
FIG. 3 is a cross-sectional view of the fuel cell according to the present embodiment, in which the fuel supply path 5 is formed in the plunger 11 of the second embodiment. According to such a configuration, in addition to the effect obtained in the second embodiment, a part of the plunger 11 which is the working part of the partition wall is used as the fuel supply path 5, so that the fuel cell is downsized. There is an effect that can be easily done.
[0050]
(Example 5)
FIG. 4 is a cross-sectional view of the fuel cell according to the present embodiment. The partition wall according to the first embodiment is not movable but is configured to be easily deformed by pressure. Therefore, when the reaction proceeds and a large amount of gas is generated and the pressure of the gas chamber 8 is increased, the partition wall 10 is deformed in a direction that contracts the volume of the fuel storage 4. As a result, the contracted volume of fuel is supplied to the anode 2. Therefore, an elastic body is suitable for the partition wall 10. As a material of the partition wall 10, for example, any of resin, rubber-like elastic body, paper coated with resin, and cloth can be used.
[0051]
According to such a configuration, since the volume change of the fuel storage 4 is obtained by the deformation of the partition wall 10, there is no mechanism portion and a highly reliable structure can be obtained.
[0052]
(Example 6)
A schematic cross section of the fuel cell of this example is shown in FIG. The fuel cell of this embodiment includes a power generation portion, a fuel supply portion, and a gas flow path. As shown in the figure, an anode electrode 2 and a cathode electrode 3 are disposed in the power generation portion with the solid electrolyte 1 interposed therebetween. The fuel supply portion includes a fuel storage 4, a fuel supply path 5 for sending fuel from the fuel storage 4 to the anode electrode 2, and an anode electrode 2 for evenly dispersing the anode electrode 2 while holding the fuel. The diffusion layer 6 is disposed between the outlets of the fuel supply path 5. The gas flow path includes a gas chamber 8 in which a gas generated by the reaction of fuel at the anode electrode 2 is present, and a gas discharge port 12 for discharging the generated gas to the outside of the fuel cell. The fuel storage 4 and the gas chamber 8 are separated by a partition wall 10. The power generation principle and fuel of this fuel cell are the same as in the first embodiment.
[0053]
In the fuel cell of this embodiment, a rotor 13 is provided at the gas discharge port 12. A rotary pump 15 is provided at the anode electrode 2 side outlet of the fuel supply path 5. Further, a train wheel mechanism 14 is provided between the rotor 13 and the pump 15.
[0054]
The rotor 13 is rotated by the gas flow when the gas generated on the anode electrode 2 passes through the gas discharge port 12 and is discharged outside the fuel cell. This rotational force is transmitted to the pump 15 by the train wheel mechanism 14 and the pump 15 is driven. Although the train wheel mechanism 14 is used in this embodiment, a fan belt or the like may be used as long as the rotational force can be transmitted efficiently. Further, depending on the arrangement method of the rotor 13 and the pump 15, the gear train mechanism 14 may not be provided by directly combining them.
[0055]
The function of the pump 15 is to supply the fuel by driving without supplying the fuel from the fuel supply path 5 to the anode electrode 2 except when the pump 15 is driven. As a result, when the pump 15 is not driven, crossover can be suppressed. Further, since the amount of gas generated varies depending on the reaction amount of the electrode reaction, the driving degree of the pump also varies. That is, when the reaction amount is large, the pressure of the gas chamber 8 rises in a short time, and the flow rate of the gas discharged from the gas discharge port 12 increases. Accordingly, the rotational speed of the rotor 13 is increased, and the rotational speed of the pump 15 is increased. As a result, more fuel can be supplied to the anode electrode 2.
[0056]
【The invention's effect】
As described above, in a fuel cell that generates electricity by supplying liquid power generation fuel directly to an electrode, a fuel supply mechanism that supplies fuel from a fuel storage to the electrode using gas generated at the electrode is provided. Yes.
[0057]
This makes it possible to effectively use products that have only been discarded. In other words, the surplus energy that was discarded is used for supplying fuel without using power. This leads to an improvement in fuel utilization efficiency.
[0058]
The fuel cell includes an electrolyte, an electrode, a gas chamber that collects gas generated on the electrode, a fuel storage, a fuel supply passage that supplies an appropriate amount of fuel from the fuel storage to the electrode, a gas chamber, and a fuel storage And has a part where the entire partition wall or a part thereof operates.
[0059]
Further, the entire partition wall or a part of the partition wall is operated by the gas pressure in the gas chamber, causing volume contraction of the fuel storage, so that the amount of fuel supplied to the electrode through the fuel supply path is variable.
[0060]
Thereby, according to the production amount of the gas produced | generated on the electrode, a fuel will be supplied to an electrode from a fuel storage. Conversely, if no gas is generated on the electrode, no fuel is supplied to the electrode. Therefore, the amount of fuel existing in the vicinity of the electrode can be suppressed within the required range, and the fuel crossover can be reduced.
[0061]
The fuel cell includes an electrolyte, an electrode, a gas chamber for collecting gas generated on the electrode, a fuel storage, a fuel supply path for supplying fuel from the fuel storage to the electrode in an appropriate amount, a gas chamber, A partition that separates the fuel storage, a pump provided in the fuel supply path, a mechanism that operates the pump, and a gas discharge valve that discharges gas from the gas chamber, and the pump is driven by the gas generated on the electrode It has a structure.
[0062]
Furthermore, the pump is operated through a mechanism that operates the pump by the pressure of gas generated on the electrode, so that the amount of fuel supplied to the electrode through the fuel supply path is variable.
[0063]
Thereby, according to the production amount of the gas produced | generated on the electrode, a fuel will be supplied to an electrode from a fuel storage. Conversely, if no gas is generated on the electrode, no fuel is supplied to the electrode. Therefore, the amount of fuel existing in the vicinity of the electrode can be suppressed within the required range, and the fuel crossover can be reduced. Moreover, since the driving force source of the pump is surplus energy called the pressure of the generated gas and not electric power, the fuel can be effectively used for small electronic devices. In addition, the mechanism can be reduced to a volume that can be incorporated into a fuel cell for a small electronic device.
[0064]
As described above, according to the present invention, it is possible to provide a fuel cell with reduced fuel crossover, small size, and high fuel utilization efficiency.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a fuel cell of the present invention.
FIG. 2 is a cross-sectional view of Example 3 fuel cell according to the present invention.
FIG. 3 is a cross-sectional view of a fuel cell of Example 4 according to the present invention.
FIG. 4 is a cross-sectional view of a fuel cell of Example 5 according to the present invention.
FIG. 5 is a cross-sectional view of a fuel cell of Example 6 according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Solid polymer electrolyte 2 Anode electrode 3 Cathode electrode 4 Fuel storage 5 Fuel supply path 6 Diffusion layer 7 Valve 8 Gas chamber 9 Gas discharge valve 10 Partition 11 Plunger 12 Gas discharge port 13 Rotor 14 Wheel train structure 15 Pump

Claims (12)

A fuel cell for generating power by supplying liquid power generation fuel to an electrode, comprising a fuel supply mechanism for supplying fuel from a fuel storage to the electrode using gas generated at the electrode Fuel cell. A fuel cell for generating power by supplying liquid power generation fuel to an electrode, comprising: a gas chamber for collecting gas generated at the electrode; and a fuel storage for storing the power generation fuel; A fuel cell characterized in that fuel is supplied from the fuel storage to the electrode by applying pressure to the fuel stored in the fuel supply storage using a change in the amount of gas stored. A fuel cell for generating power by supplying liquid power generation fuel to an electrode, comprising: a gas chamber for collecting gas generated at the electrode; and a fuel storage for storing the power generation fuel; A fuel cell, wherein fuel is supplied from the fuel storage to the electrode by changing a volume of the fuel supply storage according to a pressure change. A fuel cell that generates power by supplying liquid power generation fuel to an electrode, the gas chamber collecting gas generated at the electrode, a fuel storage for storing the power generation fuel, the gas chamber, and the gas chamber A partition provided between the fuel storages and movable by pressure received from the gas chamber, and a fuel supply path for supplying fuel from the fuel storages to the electrodes, the fuel in the fuel storages according to the movement of the partitioning Is supplied to the electrode. The fuel cell according to claim 4, wherein the partition wall includes a movable part and a fixed part, and the movable part is a plunger that operates while contacting the fixed part. The fuel cell according to claim 5, wherein the fuel supply path is formed in the plunger. The fuel cell according to claim 4, wherein the partition wall is made of a material that can be easily deformed by gas pressure in the gas chamber and cause volume shrinkage of the fuel storage. A fuel cell for generating power by supplying liquid power generation fuel to an electrode, comprising: a fuel storage for storing the power generation fuel; and a pump driven by gas generated at the electrode, and using the pump A fuel cell, wherein fuel is supplied to the electrode from a fuel storage. A gas chamber that collects gas generated by the electrode; and a gas discharge valve that discharges gas from the gas chamber, and the pump is driven by the gas in the gas chamber passing through the gas discharge valve. The fuel cell according to claim 8. The fuel cell according to claim 9, wherein a rotor that rotates when gas passes from the gas discharge valve is provided as a mechanism for driving the pump. The fuel cell according to any one of claims 1 to 10, wherein the fuel cell generates power using a solid polymer electrolyte. The fuel cell according to any one of claims 1 to 11, wherein the fuel is supplied to the electrode through a diffusion layer that holds the fuel.

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