JP2011146224A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell of passive type capable of supplying a liquid fuel and air, without having to use an auxiliary device which uses an external power, such as a pump and a fan, and which has high power generation performance capable of supplying full power. <P>SOLUTION: The fuel cell includes a unit cell 30, having a membrane electrode assembly 20 in which a fuel electrode 11, an electrolyte membrane 10, and an air electrode 12 are laminated, in this order; a fuel supply chamber 60 which is arranged at the lower part of the fuel electrode 11; a fuel storage chamber 70 which holds the liquid fuel to be supplied to the fuel electrode 11; and a fuel transport member 61 constituted of a material that exhibits capillary action to the liquid fuel, and of which one end is arranged, at a position capable of contacting the liquid fuel held inside the fuel storage chamber 70, and the other end is arranged inside the fuel supply chamber 60 and extends so as to face the fuel electrode 11. The fuel transport member 61 is provided with a gas permeation layer 62, which is a layer that covers at least a part of its surface and permeates vapor of the liquid fuel. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel cell, and more particularly to a passive fuel cell using liquid fuel transportation by capillary action.

  Fuel cells can be used for a long time, allowing users to use the electronic equipment longer than before by refilling the fuel once, and even if the user runs out of the battery on the go, the fuel cell does not have to wait for charging. From the point of convenience that an electronic device can be used immediately by purchasing and replenishing it, there is an increasing expectation for practical use as a new power source for portable electronic devices that support the information society.

  In general, a fuel cell oxidizes a hydrocarbon gas, hydrogen gas or other fuel gas or a liquid fuel such as an alcohol aqueous solution at a fuel electrode, and causes an oxidation-reduction reaction to reduce oxygen in the air at an air electrode. Give rise to

  Fuel cells are classified into a phosphoric acid type, a molten carbonate type, a solid electrolyte type, a solid polymer type, a direct alcohol type, and the like according to the classification of the electrolyte material and fuel used. In particular, solid polymer fuel cells and direct alcohol fuel cells that use an ion exchange membrane that is a solid polymer as an electrolyte material can achieve high power generation efficiency at room temperature, and are therefore intended for application to portable electronic devices. Practical application as a small fuel cell is being studied.

  In particular, a direct alcohol fuel cell that uses alcohol or an alcohol aqueous solution as a fuel has a simplified structure of the fuel cell because the fuel storage chamber can be designed relatively easily compared to the case where the fuel is a gas. It is possible to reduce the size and space, and it is highly expected as a small fuel cell for application to portable electronic devices. In a direct alcohol fuel cell that uses a cation exchange membrane as an electrolyte membrane, when a liquid fuel that is alcohol or an alcohol aqueous solution is supplied to the fuel electrode, the liquid fuel in contact with the fuel electrode is oxidized, and a gas such as carbon dioxide and Separated into protons.

For example, when methanol is used as the alcohol,
CH ₃ OH + H ₂ O → CO ₂ ↑ + 6H ⁺ + 6e ⁻
Carbon dioxide is generated on the fuel electrode side by the oxidation reaction.

Protons generated on the fuel electrode side are transmitted to the air electrode side through the electrolyte membrane. And the proton transmitted to the air electrode and the oxygen in the air supplied to the air electrode,
3 / 2O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O
This causes a reduction reaction of water to produce water. At this time, electrons pass through an external electronic device (load), move from the fuel electrode to the air electrode, and electric power is taken out.

  On the other hand, fuel cells, particularly small fuel cells, can be broadly classified into passive types and active types from classification based on fuel supply and air supply methods. A passive fuel cell is a fuel cell that supplies fuel and air to the fuel electrode and the air electrode, respectively, without using auxiliary equipment that uses external power such as a pump or a fan. Therefore, there is a high expectation for use in portable electronic devices.

  As a passive fuel cell that transports liquid fuel by utilizing capillary action, for example, Patent Document 1 discloses that a material exhibiting capillary action such as natural fiber, glass nonwoven fabric, and synthetic fiber nonwoven fabric is brought into contact with the anode and capillary action is performed. A liquid fuel cell is disclosed in which one end of a material indicating the above is in contact with the liquid fuel.

JP 59-66066 A

  In order to realize a fuel cell exhibiting good power generation performance in a passive fuel cell in which liquid fuel is transported within a fuel cell using a member made of a material exhibiting capillary action (hereinafter also referred to as a fuel transport member). The fuel transport member must have a sufficiently high “pickup height” and a sufficiently high “pickup speed”. “Sucking height” means the position where the liquid fuel can be reached by capillary action when one end of the fuel transport member is immersed in the liquid fuel. If this is small, the liquid fuel is supplied over the entire fuel electrode. And the output of the fuel cell is reduced. “Suction speed” means the volume of liquid fuel sucked up per unit time when one end of the fuel transport member is immersed in liquid fuel, and the consumption speed of liquid fuel consumed by power generation by the fuel cell On the other hand, if the suction speed is not sufficient, the liquid fuel is depleted at any part of the fuel transport member, and the liquid fuel is not supplied to the other end of the fuel transport member. Decreases. This problem of the sucking speed is particularly remarkable when a large current is taken out from the fuel cell or when the porosity of the fuel transport member is small.

  Therefore, the present invention is a passive fuel cell capable of supplying liquid fuel and air without using an auxiliary device that uses external power such as a pump and a fan, and can generate sufficient power. It aims at providing a high fuel cell.

  The present invention provides a fuel supply comprising a unit battery cell having a membrane electrode assembly formed by laminating a fuel electrode, an electrolyte membrane and an air electrode in this order, and a space disposed below the fuel electrode and opened on the fuel electrode side A liquid storage chamber, a fuel storage chamber for holding liquid fuel supplied to the fuel electrode, and a member made of a material having a capillary action on the liquid fuel, one end of which is held in the fuel storage chamber And a fuel transport member that is disposed at a position where the other end is disposed in the fuel supply chamber and extends to face the fuel electrode, and the fuel transport member covers at least a part of the surface of the fuel transport member. A fuel cell comprising a gas permeable layer that is permeable to vapor of liquid fuel.

  The fuel supply chamber includes a first opening that communicates the interior thereof with the interior of the fuel storage chamber, or communicates the interior thereof with the outside of the fuel cell. The fuel storage chamber comprises the interior thereof and the exterior of the fuel cell. It is preferable to provide the 2nd hole which communicates.

  The gas permeable layer preferably covers the surface of the fuel transport member facing the fuel electrode, and more preferably covers the surface opposite to the surface facing the fuel electrode. The gas permeable layer can be composed of a porous resin layer having pores having a pore diameter of 0.01 to 10 μm. The gas permeable layer may have a laminated structure of two or more layers.

  The fuel transport member is preferably made of a metal porous body that exhibits a capillary action on liquid fuel. The porous metal body is preferably composed of a sintered body of a metal fiber nonwoven fabric in which the fiber surface is coated with an oxide film.

  In one preferred embodiment of the fuel cell of the present invention, the fuel storage chamber is disposed on the side of the unit battery cell and the fuel supply chamber disposed below the unit battery cell, and one end of the fuel transport member is in the fuel storage chamber. The other end of the fuel electrode is disposed at a position substantially directly below the end of the fuel electrode opposite to the fuel storage chamber side.

  In the fuel cell of the present invention, as described above, the fuel supply chamber can include a first opening that communicates the inside with the outside of the fuel cell. In this case, the first opening is a fuel transport member. It is preferable to arrange | position in the said other end vicinity.

  The unit battery cell preferably further includes an anode current collecting layer laminated on the fuel electrode and a cathode current collecting layer laminated on the air electrode.

  The fuel cell of the present invention may include two or more unit battery cells, and in this case, two or more fuel transport members may be arranged to face each of the two or more unit battery cells.

  The fuel transport member provided in the fuel cell of the present invention has an excellent sucking height and sucking speed because its surface is coated with a gas permeable layer. Therefore, the fuel cell of the present invention can supply liquid fuel at a sufficient speed over the entire fuel electrode without using an auxiliary device that uses external power such as a pump or a fan. Can be supplied. In addition, the fuel transport member formed with the gas permeable layer used in the present invention has an excellent sucking speed, so that the liquid fuel quickly penetrates the inside of the fuel transport member. The time until it is taken out can be shortened.

  The fuel cell of the present invention is suitable as a small fuel cell for application to a portable electronic device having a power consumption of several watts, particularly as a small fuel cell mounted on a portable electronic device.

It is a schematic sectional drawing which shows an example of the fuel cell of this invention. FIG. 2 is a schematic top view of the fuel cell shown in FIG. 1. It is sectional drawing in the III-III line | wire shown by FIG. It is sectional drawing in the IV-IV line shown by FIG. It is sectional drawing in the VV line shown by FIG. It is sectional drawing in the VI-VI line shown by FIG. An example when a gas permeable layer is formed on the surface opposite to the fuel electrode of the fuel transport member made of a sintered metal fiber nonwoven fabric whose metal fiber surface is coated with an oxide film and on the surface opposite to the surface. It is sectional drawing shown. It is a schematic sectional drawing which shows another example of the fuel cell of this invention. It is a schematic sectional drawing which shows another example of the fuel cell of this invention. It is a schematic sectional drawing which shows another example of the fuel cell of this invention. It is a schematic sectional drawing which shows another example of the fuel cell of this invention. It is a schematic top view which shows another example of the fuel cell of this invention. FIG. 13 is a schematic top view when the fuel cell shown in FIG. 12 is cut in a direction perpendicular to the stacking direction of the constituent members at a position where the fuel transport member exists. 2 is a schematic cross-sectional view showing a fuel cell manufactured in Comparative Example 1. FIG. It is a graph which shows the length dependence of the current density obtained at the voltage 0.2V in the fuel cell of Examples 1-3 and the comparative example 1 of the fuel electrode and the air electrode.

Hereinafter, the fuel cell of the present invention will be described in detail with reference to embodiments.
FIG. 1 is a schematic sectional view showing an example of the fuel cell of the present invention, and FIG. 2 is a schematic top view of the fuel cell. 3 to 6 are sectional views taken along lines III-III, IV-IV, VV, and VI-VI shown in FIG. 1, respectively. As shown in these drawings, the fuel cell 100 shown in FIG. 1 includes a membrane electrode assembly 20 in which a fuel electrode 11, an electrolyte membrane 10 and an air electrode 12 are laminated in this order, and a fuel electrode 11. A unit battery cell 30 comprising: an anode current collecting layer 21 laminated and electrically connected thereto; and a cathode current collecting layer 22 laminated on the air electrode 12 and electrically connected thereto; (More specifically, a fuel supply chamber 60 that is disposed below the anode current collecting layer 21 and is open to the fuel electrode 11 side; holds liquid fuel (not shown) supplied to the fuel electrode 11. And one end (the left end in FIG. 1) is disposed at a position where it can come into contact with the liquid fuel held in the fuel storage chamber 70, and the other end is located inside the fuel supply chamber 60. Arranged, fuel electrode 11 (just , And a fuel transport member 61 to which the anode current collecting layer 21 extends so as to face the) are interposed. The fuel transport member 61 is made of a material that exhibits a capillary action with respect to the liquid fuel held in the fuel storage chamber 70.

  The space immediately below the fuel electrode 11 constituting the fuel supply chamber 60 is formed by the box housing 40 and the anode current collecting layer 21 that are disposed below the unit battery cell 30 so as to be in contact with the anode current collecting layer 21. That is, the box housing 40 has a recess that constitutes the fuel supply chamber 60, and is aligned so that the recess is disposed directly below the fuel electrode 11, and the opening side of the recess is the anode current collecting layer 21. The fuel supply chamber 60 is formed by laminating the box housing 40 on the anode current collecting layer 21 so as to face to each other. Further, the box housing 40 has a portion constituting the fuel supply chamber 60 of the fuel cell 100 and a portion constituting the bottom wall and side wall of the fuel storage chamber 70 as an integral unit.

  The fuel cell 100 includes a box housing 40 and a lid housing 50 stacked on the cathode current collecting layer 22 and having a plurality of openings 51. The unit battery cell 30 is sandwiched between the box housing 40 and the lid housing 50. Has been. The lid housing 50 integrally has a portion constituting the upper wall (ceiling wall) of the fuel storage chamber 70 together with a portion laminated on the cathode current collecting layer 22, and the box housing 40, the lid housing 50, and the unit. A fuel storage chamber 70 is formed by the battery cells 30. In the fuel cell 100 shown in FIG. 1, the fuel storage chamber 70 is disposed on the side of the unit battery cell 30 and the fuel supply chamber 60 disposed below the unit battery cell 30.

  The fuel supply chamber 60 includes a first opening 63 that communicates the internal space with the internal space of the fuel storage chamber 70. The first opening 63 is a through hole provided in the box housing 40. Further, the fuel storage chamber 70 includes a second opening 71 that communicates the internal space with the outside of the fuel cell 100. The second opening 71 is a through hole provided in the lid housing 50.

  Here, the fuel cell of the present invention is characterized in that at least a part of the surface of the fuel transport member is covered with a gas permeable layer that allows the vapor of the liquid fuel to permeate, and the fuel cell 100 shown in FIG. The gas permeable layer 62 covers the surface of the fuel transport member 61 facing the fuel electrode 11 and the surface opposite to the surface facing the fuel electrode 11.

  The fuel cell of the present invention generates power by the following operation. That is, referring to the fuel cell 100 shown in FIG. 1, when liquid fuel is supplied to the fuel storage chamber 70, the liquid fuel is supplied from the end of the fuel transport member 61 on the fuel storage chamber 70 side to the fuel transport member 61. It moves to the pores that have due to capillary action. The moved liquid fuel permeates the fuel transport member 61 through the pores of the fuel transport member 61 and the capillaries formed by the fuel transport member 61 and the gas permeable layer 62, and the other end of the fuel transport member 61 (fuel It reaches to the opposite end of the storage chamber 70 side).

The liquid fuel that has permeated the fuel transport member 61 and has been transported to the fuel supply chamber 60 fills the space of the fuel supply chamber 60 in a gas state via the gas permeable layer 62 that allows the vapor of the liquid fuel to permeate. The liquid fuel in a gas state filled in the space of the fuel supply chamber 60 is supplied to the fuel electrode 11 from the opening of the anode current collecting layer 21. And as an example of an aqueous methanol solution as the liquid fuel, the gaseous methanol aqueous solution supplied to the fuel electrode 11 is:
CH ₃ OH + H ₂ O → CO ₂ ↑ + 6H ⁺ + 6e ⁻
This causes an oxidation reaction represented by the formula: On the other hand, in the air electrode 12, oxygen in the air that has reached through the opening 51 of the lid housing 50 and the opening of the cathode current collecting layer 21 and the fuel electrode 11 are transmitted to the air electrode 12 through the electrolyte membrane 10. Proton
3 / 2O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O
The reduction reaction represented by the formula Due to this oxidation-reduction reaction, electrons move in the route of the fuel electrode 11 → the anode current collecting layer 21 → the external electronic device (load) → the cathode current collecting layer 22 → the air electrode 12, and the electric power is supplied to the external electronic device. Is supplied.

  The liquid fuel in the gas state in the fuel supply chamber 60 is consumed according to the amount of current consumed by the fuel cell 100. To compensate for this, the fuel transport member 61 passes through the gas permeable layer 62. Since the liquid fuel continues to evaporate as needed, the concentration of the liquid fuel in the gas state in the fuel supply chamber 60 is kept substantially constant, and sufficiently high power can be stably supplied.

  The transportation of the liquid fuel from the fuel storage chamber 70 to the fuel supply chamber 60 (the permeation movement of the liquid fuel in the fuel transporting member 61) exclusively utilizes the capillary phenomenon. In the present invention, as the liquid fuel transporting member, the fuel transporting member 61 whose surface is covered with the gas permeable layer 62 is used. Therefore, the fuel transporting member 61 and the gas permeable layer together with the capillary force of the fuel transporting member 61 itself. Capillary force is applied by the capillary formed at the interface with 62, and as a result, a very large capillary force is obtained, and a sufficiently high suction height and suction speed are realized. Therefore, the transportation of the liquid fuel from the fuel storage chamber 70 to the fuel supply chamber 60 can be performed without using external power and substantially not affected by gravity.

  As described above, in the fuel cell 100 shown in FIG. 1, since a very large capillary force is obtained in the transport of the liquid fuel from the fuel storage chamber 70 to the fuel supply chamber 60, the orientation of the fuel cell 100 during use is particularly Even if it is a case where it uses in the state where the fuel storage chamber 70 turned down and the fuel transport member 61 stood vertically upwards, for example, sufficiently high electric power can be supplied. Further, since the suction speed is high, the time for the liquid fuel to permeate (saturate) the fuel transport member 61 is shortened, so that the time from the start of the fuel cell to the extraction of power can be shortened.

Next, each member constituting the fuel cell 100 will be described in detail.
(Fuel transportation member)
The fuel transport member 61 is a member that is disposed at least in part in the fuel supply chamber 60 and transports liquid fuel from the fuel storage chamber 70 to the fuel supply chamber 60 by utilizing capillary action. It consists of the material which shows a capillary action with respect to. Examples of the material exhibiting such capillary action include acrylic resins, ABS resins, polyvinyl chloride, polyethylene, polyethylene terephthalate, polyether ether ketone, polytetrafluoroethylene and other fluororesins, and polymer materials such as cellulose ( Plastic materials) and porous bodies having irregular pores made of metal materials such as stainless steel, titanium, tungsten, nickel, aluminum, and steel. Examples of the porous body include nonwoven fabrics, foams, and sintered bodies made of the above materials. Further, a substrate made of the above polymer material or metal material and having a regular or irregular slit pattern (groove pattern) on the surface as a capillary can be used as the fuel transport member 61.

  The pore diameter of the pores of the fuel transport member 61 is preferably 0.1 to 500 μm, preferably 1 to 300 μm, in order to cause a sufficient capillary action against gravity and to obtain a good suction height and speed. More preferably. The pore diameter of the pores of the fuel transport member 61 is a diameter measured by a mercury intrusion method.

  Among the above, a metal porous body made of a metal material such as stainless steel, titanium, tungsten, nickel, aluminum, and steel is preferable. A metal fiber nonwoven fabric obtained by processing the metal material into a fiber to obtain a nonwoven fabric, and a sintered body thereof. The metal fiber nonwoven fabric sintered body which is tied and rolled as needed is more preferable, and it is still more preferable to use a metal fiber nonwoven fabric sintered body. By using the metal fiber nonwoven fabric sintered body, sufficient strength of the fuel transport member 61 can be maintained even when the porosity is increased, so that the assembly accuracy at the time of manufacturing the fuel cell can be increased. In addition, since the porosity can be increased while maintaining sufficient strength, the amount of liquid fuel that can be held by the fuel transport member 61 can be improved. This means that when the suction height is the same, the suction speed becomes larger. Therefore, the liquid fuel is effectively supplied also to the portion of the fuel electrode 11 away from the fuel storage chamber 70. It becomes possible to do.

  The fiber diameter R of the metal fiber constituting the metal fiber nonwoven fabric and the metal fiber nonwoven fabric sintered body is not particularly limited, and can be, for example, 10 to 200 μm. The porosity of the metal fiber nonwoven fabric and the metal fiber nonwoven fabric sintered body is, for example, 30 to 90%, and preferably 50 to 80% from the viewpoint of improving the suction height and the suction speed.

  Further, as a material constituting the fuel transport member 61, a metal porous body in which a passive layer made of an oxide film is formed on the fiber surface of a metal fiber nonwoven fabric sintered body made of stainless steel, titanium, tungsten, aluminum or the like is also preferably used. It is done. When the fiber surface is coated with an oxide film, the elution of metal ions from the fuel transport member 61 to the liquid fuel is prevented, so that a metal is contained in the solid electrolyte component (ion exchange resin) contained in the membrane electrode assembly 20. Ions are trapped, and there is no risk of a decrease in output. In FIG. 7, the gas permeable layer 62 is formed on the surface opposite to the fuel electrode of the fuel transport member made of the sintered metal fiber nonwoven fabric, the surface of the metal fiber 3 being coated with the oxide film 4, and on the opposite surface. An example of the time is shown in a sectional view.

  In particular, when an alcohol aqueous solution having an alcohol concentration of 50% by weight or less is used as the liquid fuel, the wettability of the liquid fuel to the fiber surface is improved by forming a passive layer made of an oxide film. The fuel sucking speed and the lifting height are further improved. Therefore, it is possible to supply the liquid fuel more effectively to the portion of the fuel electrode 11 away from the fuel storage chamber 70.

  When using a metal fiber nonwoven fabric sintered body whose fiber surface is coated with an oxide film, the fiber diameter R of the metal fiber can be, for example, 10 to 200 μm, and the film thickness d of the oxide film is 0.1 to 10 μm. It is preferable that As long as the oxide film is formed at least at the atomic level, it is possible to obtain the effect of preventing the elution of metal ions and the effect of improving the wettability of the liquid fuel to the fiber surface, but the film thickness d of the oxide film is 0.1 μm. If it is less than this, in the manufacturing process in which the gas permeable layer 62 to be described later is thermocompression bonded to the fuel transport member 61, the oxide film may be damaged, and metal elution may occur partially or the wettability may be reduced.

  The ratio R / d between the fiber diameter R of the metal fiber and the film thickness d of the oxide film preferably satisfies 10 <R / d <100. While the oxide film is extremely hard and tough, it has brittle properties, but by making R / d within the above range, a good oxide film without breakage is formed without impairing the flexibility of the metal fiber. be able to.

  In the fuel cell 100 shown in FIG. 1, the fuel transport member 61 has a strip shape, more specifically, a rectangular parallelepiped shape (see FIGS. 1 and 5). However, the shape is not limited to this, and the shape of the fuel transport member 61 can be an appropriate shape according to the shape of the entire fuel cell, the shape of the membrane electrode assembly, and the like. As other examples other than a rectangular parallelepiped shape, for example, a cubic shape, a strip shape such as a shape whose width decreases or increases continuously or stepwise from one end to the other end (a shape whose surface is a trapezoid or a triangle, etc.) Can be mentioned.

  The length of the fuel transporting member 61 (distance from one end on the fuel storage chamber 70 side to the other end facing the fuel transporting member 70) is not particularly limited, and is appropriately determined according to the shape of the entire fuel cell, the shape of the membrane electrode assembly, and the like. However, when one end of the fuel transport member 61 is disposed at a position where it can contact the liquid fuel held in the fuel storage chamber 70, the other end is the end of the fuel electrode 11 (the fuel storage chamber). It is preferable to have such a length that it is arranged at a position substantially immediately below (the end opposite to the 70 side) or longer. Thereby, the liquid fuel can be supplied more effectively over the entire fuel electrode 11 including the end of the fuel electrode 11 opposite to the fuel storage chamber 70 side.

  As shown in FIG. 1, the “position where the liquid fuel can be contacted” refers to a wall (a part of the box housing 40) at which one end of the fuel transport member 61 partitions the fuel supply chamber 60 and the fuel storage chamber 70. ) And the case where one end of the fuel transport member 61 is located inside the fuel storage chamber 70 as in the fuel cell 800 shown in FIG. By adjusting the length of the fuel transport member 61 so that one end of the fuel transport member 61 is positioned inside the fuel storage chamber 70, liquid fuel can be used regardless of the orientation of the fuel cell 100 in use. And the fuel transport member 61 can be contacted. In this case, regardless of the direction of the fuel cell 100 in use, the side surface of the end of the fuel transport member 61 located in the fuel storage chamber 70 in order to allow the liquid fuel to penetrate into the fuel transport member 61. The surface of the fuel transport member 61 is preferably not covered with the gas permeable layer 62.

  The thickness of the fuel transport member 61 is not particularly limited, and is appropriately determined according to the thickness of the fuel cell 100, the height of the fuel supply chamber 60, and the like. For example, the thickness can be about 0.05 to 5 mm. From the viewpoint of miniaturization of 100 and improvement of the siphoning height and the siphoning speed, 0.1 to 1 mm is preferable.

  In the fuel cell 100 shown in FIG. 1, the fuel transport member 61 having a strip shape has a gas permeation of the fuel transport member 61 at a position immediately below the unit battery cell 30 having a strip shape (more specifically, a rectangular parallelepiped shape). The surface on which the layer 62 is formed is disposed so as to face the fuel electrode 11. More specifically, the fuel transport member 61 is disposed at a position directly below the fuel electrode 11 via the anode current collecting layer 21 and the upper space of the fuel supply chamber 61 and transports fuel with the fuel electrode 11. The arrangement relationship with the member 61 is parallel in both the vertical direction (stacking direction of the members of the fuel cell) (see FIG. 1) and the direction perpendicular to the direction (width direction of the fuel cell) (see FIGS. 3 to 6). is there. Such an arrangement relationship between the fuel electrode 11 and the fuel transport member 61 is extremely preferable for efficiently supplying the gaseous liquid fuel evaporated from the fuel transport member 61 through the gas permeable layer 62 to the fuel electrode 11. However, it is not limited to such an arrangement relationship. For example, the fuel transport member 61 can be disposed so as to be inclined with respect to the vertical direction so as to gradually approach or separate from the fuel electrode 11 as it is separated from the fuel storage chamber 70. Further, the fuel transport member 61 may be disposed so as to intersect the fuel electrode 11 when the fuel cell 100 is viewed from above. Further, the fuel transport member 61 is not disposed at a position immediately below the fuel electrode 11 (so that the position of the fuel transport member 61 and the position of the fuel electrode 11 coincide when the fuel cell 100 is viewed from above). It may be arranged in a shifted state.

  Further, in the fuel cell 100 shown in FIG. 1, the fuel transport member 61 is disposed in the vicinity of the center in the vertical direction in the fuel supply chamber 60, but is not limited to this, for example, the center in the vertical direction It may be disposed at a place other than the vicinity of the part, may be disposed so as to be in contact with the anode current collecting layer 21, or may be disposed so as to be in contact with the bottom surface (box housing 40) of the fuel supply chamber 60.

(Gas permeable layer)
The gas permeable layer 62 is a layer that covers at least a part of the surface of the fuel transport member 61 and is permeable to liquid fuel vapor. “Possible to transmit the vapor of the liquid fuel” means that the liquid fuel in the fuel transport member 61 can be released from the outer surface of the gas permeable layer 62 in a gas state. The liquid fuel present in the gas permeable layer 62 may be in a liquid state or a gas state. By forming the gas permeable layer 62 on the surface of the fuel transporting member 61, capillaries are also formed at the interface between the fuel transporting member 61 and the gas permeable layer 62, so that a very large capillary force can be obtained. This makes it possible to improve the suction height and speed. Further, the gas permeable layer 62 is a layer that allows the vapor of the liquid fuel to permeate without permeating the liquid fuel itself. It has the function of transporting fuel. And as a result of suppressing the transportation of the liquid fuel in the liquid state to the fuel supply chamber 60 and permeating the liquid fuel in the gas state, the gas permeable layer 62 suppresses the excessive supply of the liquid fuel to the fuel electrode 11. It also plays a function. Thereby, the output fall by the crossover to the air electrode 12 of liquid fuel and the fall of fuel utilization efficiency can be suppressed effectively. Such a liquid fuel supply suppression function can be achieved when the liquid fuel has a low water content. Specifically, the liquid fuel is an alcohol aqueous solution, and the alcohol concentration is high, such as several tens mol / L to 100% by weight of alcohol. This is particularly effective in some cases, and even when such a high-concentration liquid fuel is used, the crossover of the liquid fuel can be effectively suppressed by forming the gas permeable layer 62 according to the present invention. Therefore, the fuel cell of the present invention is particularly suitable when a high-concentration liquid fuel (liquid fuel having a low water content) is used.

The gas permeable layer 62 is, for example, a sheet made of a fluorine resin such as polytetrafluoroethylene or polyvinylidene fluoride, a polyolefin resin such as polyethylene or polypropylene, an organic or inorganic polymer material such as polyimide or silicon rubber. , Having a pore having a pore diameter of about 0.01 to 10 μm, a porous sheet having the pore as a passage hole for a liquid fuel in a gas state, and no intentionally provided pores, A non-porous sheet (for example, a stretched sheet made of the above-described polymer material) in which gaps between polymer molecular chains constituting the sheet pass through the liquid fuel in a gaseous state can be used. The pore diameter of the pores of the gas permeable layer 62 is a diameter measured by a mercury intrusion method. Further, as the gas permeable layer 62, a sheet made of an inorganic material can be used. Examples of the sheet made of an inorganic material include a porous metal sheet (or plate) such as a sheet made of a metal particle sintered body obtained by sintering metal particles made of Ti, Al, Ni or the like by heating under pressure; titania From a sintered body of (TiO ₂ ) particles or silica (SiO ₂ ) particles or porous alumina (alumina having regular nano-sized pores formed by anodizing aluminum in an acidic electrolyte) Metal oxide porous sheet (or plate) such as a sheet. Among these, it is preferable to use a sheet made of a polymer material because it can be easily laminated on the fuel transport member 61 by thermocompression bonding.

  When the gas permeable layer 62 is a porous sheet having pores, the pore diameter of the pores of the gas permeable layer 62 is preferably 0.01 to 5 μm, because only liquid fuel in a gas state is transmitted. More preferably, it is 0.01-1 micrometer. In addition, when the gas permeable layer 62 is a porous sheet having pores, the porosity of the gas permeable layer 62 is not particularly limited, but can be, for example, about 20 to 90%, and high concentration liquid fuel (for example, When using a high concentration alcohol), it is preferably 20 to 50% from the viewpoint of suppressing evaporation.

  The thickness of the gas permeable layer 62 is not particularly limited and can be, for example, about 20 to 500 μm, and is preferably 100 to 500 μm from the viewpoint of preventing breakage in the manufacturing process. When the gas permeable layer 62 is a sheet made of a polymer material bonded to the fuel transport member 61 by thermocompression bonding, the gas permeable layer 62 has a pore diameter (preferably 0) of the pores existing on the surface of the fuel transport member 61. It is preferable to have a thickness of about 0.5 to 10 times that of (.1 to 100 μm). As a result, the gas permeable layer 62 is physically joined to the irregularities formed by the pores existing on the surface of the fuel transport member 61 by the anchor effect, so that the fuel transport can be performed without using an adhesive or the like. The member 61 and the gas permeable layer 62 can be firmly bonded. When the fuel transport member 61 and the gas permeable layer 62 are bonded using an adhesive, particularly when a high-concentration alcohol such as pure methanol is used as the liquid fuel, the adhesive swells and dissolves and the gas permeable layer 62 is formed. Although peeling may occur, according to bonding by thermocompression bonding, problems such as peeling of the gas permeable layer 62 can be suppressed even when high-concentration liquid fuel is used. As a suitable example of the gas permeable layer 62 in the case of using a high-concentration liquid fuel, a stretched sheet (polymer chain) having a thickness of 20 to 500 μm made of a polymer material such as polytetrafluoroethylene, polyvinylidene fluoride, or polyethylene is used. Non-porous sheet) in which the gap is a passage hole for the liquid fuel in the gaseous state.

  As described above, the gas permeable layer 62 can have a function of suppressing excessive supply of liquid fuel to the fuel electrode 11. The fuel supply suppressing ability of such a gas permeable layer 62 is, for example, a gas It can be controlled by adjusting the thickness, pore diameter, porosity, pore wettability, and the like of the transmission layer 62. As an example of a gas permeable layer having an optimum fuel supply suppressing ability when pure methanol is used as a liquid fuel, polytetrafluoroethylene having a thickness of 100 to 500 μm, a pore diameter of 0.01 to 1 μm, and a porosity of 20 to 80% And a porous sheet having pores made of a polymer material such as polyvinylidene fluoride or polyethylene, and the inner surface of the pore can be introduced with a functional group such as a fluoroalkyl group or a silyl group, It is preferable that an oil-repellent treatment in which a fine uneven shape is formed is performed. On the other hand, when using a relatively low concentration liquid fuel such as a 50% by weight or less aqueous methanol solution, the inner surface of the pores of the gas permeable layer 62 is preferably subjected to a hydrophilic treatment. Examples of the hydrophilization treatment include a method of impregnating a water-soluble solvent having a low surface tension in advance, substituting it with an aqueous solution of hydrogen peroxide or a water-soluble organic solvent, and irradiating with laser light. By the hydrophilization treatment, a stronger capillary force can be obtained in the space formed between the pores of the fuel transport member 61 and the gas permeable layer.

  As in the example shown in FIG. 9, the gas permeable layer 62 may have a laminated structure including two or more layers. In the fuel cell 900 shown in FIG. 9, the gas permeable layer includes a first gas permeable layer 62a formed in contact with the surface of the fuel transport member 61 facing the fuel electrode 11 and the surface opposite to the surface. The second gas permeable layer 62b is laminated thereon. For example, the first gas permeable layer 62a is a hydrophilic gas permeable layer produced by the hydrophilic treatment method as described above, and the second gas permeable layer 62b is a repellent material produced by stretching a fluororesin. By using an aqueous gas permeable layer, while obtaining a stronger capillary force in the space generated between the pores of the fuel transport member 61 and the first gas permeable layer 62a, the second gas permeable layer 62b It is possible to prevent the liquid fuel in the liquid state from oozing out from the fuel transport member 61.

  The configuration in which the gas permeable layer has a laminated structure including two or more layers is also effective as a means for controlling the above-described fuel supply suppression capability. For example, an organic solvent solution or dispersion of a polyolefin resin is applied onto the first gas permeable layer 62a made of a porous sheet of a polymer material and dried, and the gap between the polymer chains is made of a liquid fuel in a gaseous state. By forming the second gas permeable layer 62b made of a non-porous layer serving as a passage hole, the fuel supply suppressing ability of the gas permeable layer can be further enhanced. At this time, the thickness of the second gas permeable layer 62b may be constant, but when the liquid fuel is an alcohol aqueous solution or alcohol, the thickness may be reduced as the distance from the fuel storage chamber 70 increases. preferable. The side near the fuel storage chamber 70 of the fuel transport member 61 has a large amount of alcohol evaporation, and the alcohol evaporation amount decreases as the alcohol concentration decreases as the distance from the fuel storage chamber 70 increases. By providing the above-described inclination to the thickness of 62b, the excessive supply of the liquid fuel is moderately suppressed on the side close to the fuel storage chamber 70, and sufficient liquid fuel can be provided even at a site away from the fuel storage chamber 70. Supply becomes possible, and a uniform reaction can be performed within the surface of the fuel electrode 11.

  In the present invention, the gas permeable layer 62 only needs to cover at least a part of the surface of the fuel transport member 61. However, like the fuel cell 100 shown in FIG. 1 or the fuel cell 1000 shown in FIG. It is preferable to cover the surface of the fuel transport member 61 that faces the fuel electrode 11. As a result, sufficient suction height and suction speed can be improved, and the fuel supply suppression function is exhibited, so that output reduction due to crossover of liquid fuel to the air electrode 12 can be effectively suppressed. In order to further improve the suction height and the suction speed, it is more preferable that the gas permeable layer 62 covers the surface opposite to the surface of the fuel transport member 61 opposite to the fuel electrode 11 (see FIG. 1). ). The gas permeable layer 62 may further cover an end side surface opposite to the fuel storage chamber 70 side. The gas permeable layer 62 may cover only the surface opposite to the surface facing the fuel electrode 11, but the gas permeable layer 62 exhibits a fuel supply suppressing function and suppresses crossover. Moreover, it is preferable that at least the surface of the fuel transport member 61 facing the fuel electrode 11 is covered with the gas permeable layer 62.

(Electrolyte membrane)
The electrolyte membrane 10 constituting the membrane electrode assembly 20 is the same as the electrolyte membrane in the membrane electrode assembly of the present invention in that protons are transmitted from the fuel electrode 11 to the air electrode 12, and the electricity between the fuel electrode 11 and the air electrode 12. It has the function of maintaining the electrical insulation and preventing short circuit. The material of the electrolyte membrane is not particularly limited as long as it has proton conductivity and electrical insulation, and a polymer membrane, an inorganic membrane, or a composite membrane can be used. As the polymer membrane, for example, Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.), which is a perfluorosulfonic acid electrolyte membrane, etc. Can be mentioned. Also, styrene-based graft polymer, trifluorostyrene derivative copolymer, sulfonated polyarylene ether, sulfonated polyetheretherketone, sulfonated polyimide, sulfonated polybenzimidazole, phosphonated polybenzimidazole, sulfonated polyphosphazene. And hydrocarbon-based electrolyte membranes.

  Examples of the inorganic film include films made of phosphate glass, cesium hydrogen sulfate, polytungstophosphoric acid, ammonium polyphosphate, and the like. Examples of the composite film include a composite film of an inorganic material such as tungstic acid, cesium hydrogen sulfate, and polytungstophosphoric acid and an organic material such as polyimide, polyetheretherketone, and perfluorosulfonic acid.

  The film thickness of the electrolyte membrane 10 is, for example, 1 to 200 μm. The EW value (dry weight per mole of proton functional groups) of the electrolyte membrane 10 is preferably about 800 to 1100. The smaller the EW value, the lower the resistance of the electrolyte membrane accompanying proton transfer and the higher output can be obtained. However, in practice, it is difficult to make it extremely small due to the problem of dimensional stability and strength of the electrolyte membrane. .

(Fuel electrode and air electrode)
The fuel electrode 11 laminated on one surface of the electrolyte membrane 10 and the air electrode 12 laminated on the other surface are provided with a catalyst layer composed of a porous layer having at least a catalyst and an electrolyte. The catalyst for the fuel electrode 11 decomposes a liquid fuel such as a methanol aqueous solution into protons and electrons, and the electrolyte has a function of conducting the generated protons to the electrolyte membrane 10. The catalyst for the air electrode 12 has a function of generating water from protons conducted through the electrolyte and oxygen in the air.

  The catalyst for the fuel electrode 11 and the air electrode 12 may be supported on the surface of a conductor such as carbon or titanium, and in particular, carbon or titanium having a hydrophilic functional group such as a hydroxyl group or a carboxyl group. It is preferably carried on the surface of the conductor. Thereby, the water retention of the fuel electrode 11 and the air electrode 12 can be improved. The electrolyte of the fuel electrode 11 and the air electrode 12 is preferably made of a material having an EW value smaller than the EW value of the electrolyte membrane 10. Specifically, the electrolyte is the same material as the electrolyte membrane 10, but the EW value. An electrolyte material having a thickness of 400 to 800 is preferred. The water retention of the fuel electrode 11 and the air electrode 12 can also be improved by using such an electrolyte material. By improving the water retention of the fuel electrode 11 and the air electrode 12, it is possible to improve the resistance of the electrolyte membrane 10 accompanying proton transfer and the potential distribution in the fuel electrode 11 and the air electrode 12. In addition, since the electrolyte with a low EW value has a high permeability of the liquid fuel at the same time, the liquid fuel in a gas state can be uniformly supplied to the catalyst layer of the fuel electrode 11 by using the electrolyte with a low EW value.

  Each of the fuel electrode 11 and the air electrode 12 may include an anode conductive porous layer and a cathode conductive porous layer laminated on the catalyst layer. These porous layers have a function of diffusing the gas (gas fuel liquid or air) supplied to the fuel electrode 11 and the air electrode 12 in the plane, and a function of exchanging electrons with the catalyst layer. . As the anode conductive porous layer and the cathode conductive porous layer, since the specific resistance is small and the decrease in voltage is suppressed, carbon materials; conductive polymers; noble metals such as Au, Pt, Pd; Ti, Porous materials comprising transition metals such as Ta, W, Nb, Ni, Al, Cu, Ag, Zn; nitrides or carbides of these metals; and alloys containing these metals typified by stainless steel Is preferably used. In the case of using a metal having poor corrosion resistance in an acidic atmosphere, such as Cu, Ag, Zn, etc., noble metals having resistance to corrosion such as Au, Pt, Pd, conductive polymers, conductive nitrides, conductive Surface treatment (film formation) may be performed with carbide, conductive oxide, or the like. More specifically, as the anode conductive porous layer and the cathode conductive porous layer, for example, foam metal, metal fabric and metal sintered body made of the above-mentioned noble metal, transition metal or alloy; and carbon paper, carbon cloth, An epoxy resin film containing carbon particles can be suitably used.

(Anode current collection layer and cathode current collection layer)
The anode current collecting layer 21 and the cathode current collecting layer 22 are laminated on the fuel electrode 11 and the air electrode 12, respectively, and constitute a unit battery cell 30 together with the membrane electrode assembly 20. Each of the anode current collecting layer 21 and the cathode current collecting layer 22 has a function of collecting electrons in the fuel electrode 11 and the air electrode 12 and a function of performing electrical wiring. The material of the current collecting layer is preferably a metal because it has a small specific resistance and suppresses a decrease in voltage even when a current is taken in the plane direction. In particular, it has electron conductivity and has an acidic atmosphere. More preferably, the metal has corrosion resistance. Such metals include noble metals such as Au, Pt, Pd; transition metals such as Ti, Ta, W, Nb, Ni, Al, Cu, Ag, Zn; and nitrides or carbides of these metals; and And alloys containing these metals typified by stainless steel. In the case of using a metal having poor corrosion resistance in an acidic atmosphere, such as Cu, Ag, Zn, etc., noble metals having resistance to corrosion such as Au, Pt, Pd, conductive polymers, conductive nitrides, conductive Surface treatment (film formation) may be performed with carbide, conductive oxide, or the like. When the anode conductive porous layer and the cathode conductive porous layer are made of, for example, metal and the conductivity is relatively high, the anode current collecting layer and the cathode current collecting layer may be omitted.

  More specifically, the anode current collecting layer 21 includes a mesh made of the above metal material or the like, which includes a plurality of through holes penetrating in the thickness direction for guiding the liquid fuel in a gas state from the fuel supply chamber 60 to the fuel electrode 11. It can be a flat plate having a shape or a punching metal shape. This through hole also functions as a discharge hole for guiding exhaust gas (carbon dioxide gas or the like) generated in the catalyst layer of the fuel electrode 11 to the fuel supply chamber 60. Similarly, the cathode current collecting layer 22 is provided with a plurality of through holes penetrating in the thickness direction for supplying air outside the fuel cell to the catalyst layer of the air electrode 12, and is formed into a mesh shape or a punching metal shape made of the above metal material or the like. It can be a flat plate.

(Fuel supply room)
The fuel supply chamber 60 is preferably disposed immediately below the fuel electrode 11, and includes a fuel transport member 61 whose surface is covered with the gas permeable layer 62 described above. The internal space of the fuel supply chamber 60 preferably has a length equal to or longer than the length from the end of the fuel electrode 11 on the side of the fuel storage chamber 70 to the end on the opposite side. It has a width equal to or greater than the width of the pole 11. The height (depth) of the internal space of the fuel supply chamber 60 is not particularly limited as long as the fuel transport member 61 whose surface is covered with the gas permeable layer 62 can be installed.

  In the fuel cell 100 shown in FIG. 1, the fuel supply chamber 60 is a box housing having a recess that constitutes an internal space of the fuel supply chamber 60 and is disposed below the unit battery cell 30 so as to be in contact with the anode current collecting layer 21. 40 and the anode current collecting layer 21. The box housing 40 integrally has a portion constituting the fuel supply chamber 60 and a portion constituting the bottom wall and side wall of the fuel storage chamber 70. However, the present invention is not limited to this. The member constituting the chamber 60 and the member constituting the fuel storage chamber 70 may be different members.

  The box housing 40 can be manufactured by using a plastic material or a metal material and molding it into an appropriate shape so as to have at least a recess that constitutes the internal space of the fuel supply chamber 60. Examples of the plastic material include polyphenylene sulfide (PPS), polymethyl methacrylate (PMMA), acrylonitrile butadiene styrene (ABS), polyvinyl chloride, polyethylene (PE), polyethylene terephthalate (PET), polyether ether ketone (PEEK). ), Polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and the like. As the metal material, for example, alloy materials such as stainless steel and magnesium alloy can be used in addition to titanium and aluminum. Among these, polyphenylene sulfide (PPS) and polyethylene (PE) are preferably used because they have high strength and can be processed inexpensively due to an increase in molecular weight due to three-dimensional crosslinking, and are lightweight.

  The fuel supply chamber 60 preferably has a first opening 63 for discharging exhaust gas (carbon dioxide gas or the like) generated in the catalyst layer of the fuel electrode 11 from the internal space of the fuel supply chamber 60. In the fuel cell 100 shown in FIG. 1, the first opening 63 is a hole that communicates the internal space of the fuel supply chamber 60 and the internal space of the fuel storage chamber 70 (a box housing constituting the internal space of the fuel supply chamber 60. 40 is a through-hole provided in a wall. As will be described later, the fuel storage chamber 70 is provided with a second opening 71 that communicates the internal space with the outside of the fuel cell. Therefore, the exhaust gas generated in the catalyst layer of the fuel electrode 11 is the fuel. The fuel is discharged outside the fuel cell through the supply chamber 60, the first opening 63, the fuel storage chamber 70, and the second opening 71 in this order.

  Further, since the first opening 63 and the second opening 71 are provided, the inside of the fuel supply chamber 60 is always maintained at the atmospheric pressure, so that the high suction height and the suction speed of the fuel transport member 61 are maintained. can do. That is, it is possible to prevent liquid fuel from permeating into the fuel transport member 61 and the fuel supply chamber 60 to be in a pressurized state, thereby reducing the suction height and the suction speed of the fuel transport member 61. In order to effectively prevent such a reduction in the suction height and the suction speed, the cross-sectional area of the first opening 63 that communicates the internal space of the fuel supply chamber 60 and the internal space of the fuel storage chamber 70 has It is preferable that the cross-sectional area of the pores of the transport member 61 is larger. As a result, the exhaust gas generated in the fuel electrode 11 passes through the first opening 63 rather than the pressure loss when the liquid fuel in the fuel transport member 61 is discharged to the fuel storage chamber 70 while pushing the liquid fuel back to the fuel storage chamber 70. Thus, the pressure loss when discharged to the fuel storage chamber 70 is much smaller, and therefore the lowering of the suction height and the suction speed of the fuel transport member 61 is effectively prevented. However, the cross-sectional area of the first opening 63 is large enough that the liquid fuel held in the fuel storage chamber 70 does not directly enter the first opening 63 and leak into the fuel supply chamber 60. Alternatively, a gas-liquid separation membrane (for example, a porous membrane made of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, or the like) for preventing liquid fuel from leaking into the fuel supply chamber 60 is first used. It is preferable to provide in the opening 63.

  The first opening 63 for discharging the exhaust gas generated in the fuel electrode 11 from the fuel supply chamber 60 needs to be a hole that connects the internal space of the fuel supply chamber 60 and the internal space of the fuel storage chamber 70. For example, as in the fuel cell 1100 shown in FIG. 11, a hole that directly communicates the internal space of the fuel supply chamber 60 and the outside of the fuel cell (the portion constituting the bottom wall of the fuel supply chamber 60 in the box housing 40). May be a through-hole provided in). In this case, the fuel supply chamber 60 and the outside of the fuel cell communicate with each other only in the gas phase without passing through the liquid phase (the first opening 63 is connected to the internal space of the fuel supply chamber 60 and the fuel storage chamber). When the liquid level of the liquid fuel held in the fuel storage chamber 70 exceeds the installation position of the first opening 63, the inside of the fuel supply chamber 60 and the fuel cell are communicated with each other. The pressure loss for discharging the exhaust gas can be further reduced, and the suction height and the suction speed of the fuel transport member 61 are further improved. be able to. In particular, at the time of starting the fuel cell, the liquid fuel instantaneously permeates the fuel transport member 61. Therefore, it is possible to further shorten the time from when the fuel cell is started until power is taken out.

  When the first opening 63 is a hole that directly communicates the internal space of the fuel supply chamber 60 and the outside of the fuel cell, the first opening 63 should be disposed as far as possible from the fuel storage chamber 70. It is preferable that the fuel transporting member 61 is disposed in the vicinity of the end opposite to the fuel storage chamber 70 side. When the liquid fuel is an aqueous alcohol solution (such as an aqueous methanol solution), the alcohol concentration of the liquid fuel in the gas state discharged through the gas permeable layer 62 becomes higher as it is closer to the fuel storage chamber 70. Since the concentration decreases as it approaches the end opposite to the fuel storage chamber 70 side, the first aperture 63 is provided at the position as described above, so that the first The amount of alcohol discharged from the opening 63 can be reduced. In order to further reduce the liquid fuel discharged from the first opening 63, it is also preferable to form a porous layer including a catalyst for burning the liquid fuel in the first opening 63.

  Note that, in the first opening 63, particularly in the first opening 63 that communicates the internal space of the fuel supply chamber 60 and the internal space of the fuel storage chamber 70, the inside of the opening is wet with liquid fuel. In order to suppress an increase in pressure loss when the exhaust gas passes, it is preferable to reduce wettability inside the first opening 63 with respect to the liquid fuel. Examples of a method for reducing the wettability include a method of performing water repellent treatment on the inner wall surface of the aperture or filling a water repellent porous material in the aperture. However, depending on the concentration and surface tension of the liquid fuel to be used, it may be preferable to perform oil repellent treatment instead of water repellent treatment. For example, when pure methanol is used as the liquid fuel, it is preferable to apply an oil repellency treatment to the inner wall surface of the opening or to fill the opening with an oil repellent porous material.

  The diameter of the first opening 63 can be set to, for example, 1 to 1000 μm, and preferably 10 to 500 μm.

(Fuel storage room)
The fuel storage chamber 70 is a chamber for holding liquid fuel, which is preferably disposed on the side of the unit battery cell 30 and the fuel supply chamber 60. The size and shape of the fuel storage chamber 70 are not particularly limited, but one end of the fuel transport member 61 covered with the gas permeable layer 62 disposed in the fuel supply chamber 60 and the liquid fuel held in the fuel storage chamber 70 It is necessary to have an opening in the side wall surface so that can be contacted. The opening may be formed from a hole penetrating a wall constituting a part of the box housing 40 that partitions the fuel supply chamber 60 and the fuel storage chamber 70. In this case, the fuel transport member 61 It is inserted into the hole so that one end is located inside the hole (FIG. 1) or located inside the fuel storage chamber 70 (FIG. 8).

  In the fuel cell 100 shown in FIG. 1, the fuel storage chamber 70 is formed by a lid housing 50, a box housing 40 and a unit battery cell 30 which are stacked on the cathode current collecting layer 22 and have a plurality of openings 51. However, it is not always necessary to configure the fuel storage chamber 70 using the lid housing 50 and the box housing 40. For example, the fuel storage chamber 70 may be provided with portions that form the upper wall (ceiling wall), side walls, and bottom wall of the fuel storage chamber 70. It can also be comprised from one member included as one.

  In the fuel cell 100 shown in FIG. 1, the lid housing 50 forms an upper wall (ceiling wall) of the fuel storage chamber 70 and prevents the unit battery cells 30 from being directly exposed. A plurality of openings 51 for allowing air to circulate (however, the number of openings may be one or more) is formed in a portion of the lid housing 50 immediately above the air electrode 12.

  The lid housing 50 can be manufactured by using a plastic material or a metal material and molding it into an appropriate shape. Examples of the plastic material include polyphenylene sulfide (PPS), polymethyl methacrylate (PMMA), acrylonitrile butadiene styrene (ABS), polyvinyl chloride, polyethylene (PE), polyethylene terephthalate (PET), polyether ether ketone (PEEK). ), Polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and the like. As the metal material, for example, alloy materials such as stainless steel and magnesium alloy can be used in addition to titanium and aluminum. Among these, polyphenylene sulfide (PPS) and polyethylene (PE) are preferably used because they have high strength and can be processed inexpensively due to an increase in molecular weight due to three-dimensional crosslinking, and are lightweight.

  The fuel storage chamber 70 preferably includes a second opening 71 that communicates the internal space with the outside of the fuel cell. Thereby, even when the liquid fuel is transported to the fuel supply chamber 60 by the fuel transport member 61, the fuel storage chamber 70 is maintained at atmospheric pressure, so that the transport of the liquid fuel is not hindered, and the fuel transport member 61. High wicking height and wicking speed can be maintained. When the first opening 63 is a hole that communicates the internal space of the fuel supply chamber 60 and the internal space of the fuel storage chamber 70, the second opening 71 allows the exhaust gas generated at the fuel electrode 11 to flow outside the fuel cell. It also has a function to discharge to In the fuel cell 100 shown in FIG. 1, the second opening 71 is a through hole that penetrates the lid housing 50 in the thickness direction, but is not limited thereto.

  In order to prevent leakage of the liquid fuel from the second opening 71, the opening diameter of the second opening 71 is preferably sufficiently small (for example, a diameter of about 100 to 500 μm, preferably 100 to 300 μm), or And providing a gas-liquid separation membrane (for example, a porous membrane made of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, or the like) in the second opening 71 for preventing leakage of liquid fuel to the outside of the fuel cell. Is preferred.

  In particular, when the second opening 71 has a function of discharging the exhaust gas generated at the fuel electrode 11 to the outside of the fuel cell, the exhaust gas due to the inside of the second opening 71 being wet with liquid fuel. In order to suppress an increase in pressure loss during passage, it is preferable to reduce wettability inside the second opening 71 with respect to the liquid fuel. Examples of a method for reducing the wettability include a method of performing water repellent treatment on the inner wall surface of the aperture or filling a water repellent porous material in the aperture. However, depending on the concentration and surface tension of the liquid fuel to be used, it may be preferable to perform oil repellent treatment instead of water repellent treatment. For example, when pure methanol is used as the liquid fuel, it is preferable to apply an oil repellency treatment to the inner wall surface of the opening or to fill the opening with an oil repellent porous material.

  As described above, the fuel cell of the present invention has been described with reference to the embodiment in which the fuel cell includes one unit battery cell. However, the fuel cell of the present invention is not limited to such a configuration. 2 or more may be included. As an example, FIG. 12 shows a schematic top view of a fuel cell having four unit battery cells 30. The layer configuration of this fuel cell may be the same as in FIG. FIG. 13 is a schematic top view when cut in a direction perpendicular to the stacking direction of the constituent members at the position where the fuel transport member 61 exists, and is a cross-sectional view taken along the line VV shown in FIG. It is an equivalent figure.

  In the fuel cells shown in FIGS. 12 and 13, each unit battery cell 30 has a strip shape (more specifically, a rectangular parallelepiped shape) like the fuel cell 100 in FIG. Are arranged so as to be parallel to each other. The width L of the gap provided between the unit battery cells 30 is, for example, about 0.5 to 10 mm. However, the unit battery cells are not necessarily arranged in parallel.

  When the fuel cell has a plurality of unit battery cells 30, the fuel transport member 61 is disposed in the fuel supply chamber 60 so as to face each unit battery cell, as shown in FIG. These members (comb teeth) may be one comb-shaped member integrated on the fuel storage chamber 70 side, or the unit battery cells 30 arranged so as to face the unit battery cells 30 respectively. The same number of fuel transport members 61 may be provided. In the example shown in FIGS. 12 and 13, the same number of fuel supply chambers 60 as the unit battery cells 30 are provided. However, the present invention is not limited to this. For example, a plurality of unit battery cells 30 may be provided. Only one fuel supply chamber 60 may be provided, and a plurality of fuel transport members 61 (or one fuel transport member 61 having a plurality of comb teeth) may be installed in the fuel supply chamber 60. Other possible modifications of the fuel cell including a plurality of unit battery cells are the same as those of the fuel cell including one unit battery cell described above.

  Examples of the liquid fuel that can be used in the fuel cell of the present invention include alcohols such as methanol and ethanol, acetals such as dimethoxymethane, carboxylic acids such as formic acid; esters such as methyl formate; An aqueous solution of The liquid fuel is not limited to one type, and may be a mixture of two or more types. In view of low cost, high energy density per volume, high power generation efficiency, etc., an aqueous methanol solution or pure methanol is preferably used.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Example 1>
A fuel cell having the same configuration as the fuel cell shown in FIGS.

(1) Production of fuel transport member 61 covered with gas permeable layer 62 Sintered titanium fiber nonwoven fabric with fiber diameter R 20 μm, thickness 0.8 mm, basis weight 700 g / m ² , porosity 81%, pore diameter 200 μm A product (manufactured by Vekinit Co., Ltd.) was prepared and cut into a width of about 30 mm and a length of about 60 mm to obtain a fuel transport member 61. In addition, a polyvinylidene fluoride membrane filter (hydrophilic durapore, manufactured by Millipore), which is a porous body having a pore diameter of 0.1 μm, a film thickness of 125 μm, and a porosity of 85%, is also prepared. Two gas-permeable layers 62 were produced by cutting to 60 mm. Next, the gas permeable layer 62 is superposed on both surfaces of the fuel transport member 61 so that their centers completely coincide with each other, and then the fuel transport member is completely used by using a stainless steel gap gauge having a thickness of 0.5 mm. While preventing the 61 from being crushed, the fuel transport member 61 and the gas permeable layer 62 were thermocompression bonded by a hot press (130 ° C., 5 kN). The obtained laminate was cut into a width of 18 mm and a length of 50 mm, and a fuel transport member 61 (hereinafter referred to as a gas transport layer-equipped fuel transport member A) having a thickness of 0.5 mm and coated on both sides with a gas permeable layer 62. ) When the obtained fuel transport member A with a gas permeable layer was immersed in methanol, ethanol, and acetone for 24 hours, the gas permeable layer was not peeled off, and even when a high concentration fuel was used. It turns out that there is no structural problem.

(2) Production of membrane electrode assembly 20 Catalyst-supported carbon particles (TEC66E50, manufactured by Tanaka Kikinzoku Co., Ltd.) having a Pt loading amount of 32.5% by weight and a Ru loading amount of 16.9% by weight, and 20% by weight of Nafion as an electrolyte (Registered trademark) alcohol solution (manufactured by Aldrich), n-propanol, isopropanol, and zirconia balls are put in a fluorine resin container at a predetermined ratio and mixed at 500 rpm for 50 minutes using a stirrer. As a result, a catalyst paste for the fuel electrode 11 was produced. Further, a catalyst paste for the air electrode 12 was prepared in the same manner as the catalyst paste for the fuel electrode 11 using catalyst-supported carbon particles (TEC10E50E, manufactured by Tanaka Kikinzoku Co., Ltd.) having a Pt loading amount of 46.8% by weight.

Next, after cutting a carbon paper (25BC, manufactured by SGL) having a water-repellent porous layer on one side into a width of about 30 mm and a length of about 50 mm, the fuel electrode 11 is formed on the porous layer. The anode conductive porous layer was applied by using a screen printing plate having a window with a width of 25 mm and a length of 45 mm so that the amount of catalyst supported was about 3 mg / cm ² and dried. A fuel electrode 11 having an anode catalyst layer formed at the center on the carbon paper and having a thickness of about 200 μm was produced. A screen having a window of 25 mm width and 45 mm length on the porous layer of carbon paper of the same size so that the catalyst loading amount of the catalyst paste for the air electrode 12 is about 1 mg / cm ^2. By applying and drying using a printing plate, an air electrode 12 having a thickness of about 200 μm in which a cathode catalyst layer was formed at the center on the carbon paper as the cathode conductive porous layer was produced.

  Next, a perfluorosulfonic acid ion exchange membrane having a thickness of about 175 μm (Nafion (registered trademark) 117, manufactured by DuPont) is cut into a width of about 30 mm and a length of 60 mm to form an electrolyte membrane 10. After superposing the electrolyte membrane 10 and the air electrode 12 in this order so that the respective catalyst layers face the electrolyte membrane 10, hot pressing is performed at 130 ° C. for 2 minutes, so that the fuel electrode 11 and the air electrode 12 are Bonded to the electrolyte membrane 10. The superposition was performed so that the positions of the fuel electrode 11 and the air electrode 12 in the plane of the electrolyte membrane 10 coincided, and the centers of the fuel electrode 11, the electrolyte membrane 10 and the air electrode 12 coincided. Next, both ends of the long side of the obtained laminate were cut to produce a membrane electrode assembly 20 having a width of 20 mm and a length of 60 mm.

(3) Production of unit battery cell 30 A stainless steel plate (NSS445M2, manufactured by Nisshin Steel Co., Ltd.) having a thickness of 100 μm, a width of 20 mm, and a length of 60 mm is prepared, and a plurality of openings having an aperture diameter of φ0.6 mm are provided in this central region. By processing holes (opening pattern: staggered 60 ° pitch 0.8mm) from both sides by wet etching using a photoresist mask, two stainless plates with multiple through holes penetrating in the thickness direction are produced. These were used as the anode current collecting layer 21 and the cathode current collecting layer 22.

  Next, the anode current collecting layer 21 is laminated on the fuel electrode 11 via a conductive adhesive layer made of carbon particles and an epoxy resin, and the cathode current collecting layer 22 is formed on the air electrode 12 with carbon particles. A unit battery cell 30 was fabricated by laminating via a conductive adhesive layer composed of a resin and an epoxy resin, and joining them by hot pressing. The anode current collecting layer 21 and the cathode current collecting layer 22 were laminated so that the regions where the holes were formed were arranged immediately above the fuel electrode 11 and the air electrode 12, respectively.

(4) Production of box housing 40 On a resin substrate (PPS) made of polyphenylene sulfide having a width of 25 mm, a length of 80 mm, and a thickness of 3 mm, a recess having a width of 23 mm, a length of 15 mm, and a depth of 2 mm is formed. In addition to cutting, a recess 18 mm in width, 45 mm in length, and 2 mm in depth forming the fuel supply chamber 60 was cut into a box housing 40. In addition, the upper part of the partition wall located between the recess forming the fuel storage chamber 70 and the recess forming the fuel supply chamber 60 was cut to a depth of 1 mm and a width of 18 mm.

(5) Production of lid housing 50 A resin substrate made of polyphenylene sulfide (PPS) having a width of 25 mm, a length of 80 mm, and a thickness of 3 mm is prepared, and 23 × 2 mm in an area disposed immediately above the air electrode 12 by cutting. In addition, a through hole having a diameter of 0.2 mm was formed as a second opening 71 in a portion constituting the ceiling wall of the fuel storage chamber 70.

(6) Fabrication of the fuel cell 100 One end of the gas transport layer-attached fuel transport member A is disposed on the partition wall on which the box housing 40 has been cut, and the other end is approximately the fuel. The fuel transport member A with a gas permeable layer was disposed so as to be located immediately below the end of the pole 11 opposite to the fuel storage chamber 70 side. At this time, the fuel transport member A with a gas permeable layer was disposed at a position immediately below the fuel electrode 11 so as to be parallel to the fuel electrode 11. Next, on the portion of the fuel transport member A with the gas permeable layer disposed on the partition wall, the first opening 63 has a width of 18 mm, a length of 10 mm, a thickness of 0.8 mm, and a porosity of 80%. The porous filters made of polytetrafluoroethylene were overlaid. Further, the unit battery cell 30 is placed on the gasket (and the fuel storage chamber) so that the thickness of the gasket formed of a silicon sheet is superimposed on the porous filter, and the space for forming the fuel supply chamber 60 is covered. In the area opposite to the 70 side, it was arranged on the box housing 40). At this time, the unit battery cell 30 was arranged such that the anode current collecting layer 21 side was the gasket side (fuel supply chamber 60 side). Then, on the cathode current collecting layer 22 of the unit battery cell 30, the above-described lid housing 50 was laminated so that the plurality of openings 51 were disposed immediately above the air electrode 12, thereby manufacturing the fuel cell 100. In this embodiment, the box housing 40 and the lid housing 50 are screwed to apply pressure in the stacking direction of each member to fix each member. The transport member A, the fuel transport member A with gas permeable layer and the porous filter, the gasket and the porous filter, the unit battery cell 30 and the lid housing 50 are various types such as thermocompression bonding using a hot-melt agent and bonding with a double-sided tape. You may join by the method. Further, referring to FIG. 6, the side surfaces of the respective members from the cathode current collecting layer 22 to the gas permeable layer 62 and the side surfaces of the box housing 40 are joined by filling with a liquid sealing agent and solidifying it. Also good.

<Example 2>
A fuel transport member B with a gas permeable layer in which the gas permeable layer 62 is formed only on the surface facing the fuel electrode 11 is produced, and the fuel cell shown in FIG. A fuel cell having the same configuration was produced.

<Example 3>
The fuel transport member C with the gas permeable layer having the gas permeable layer 62 formed only on the surface opposite to the surface facing the fuel electrode 11 is manufactured, and the fuel cell is the same as in Example 1 except that this is used. Was made.

<Example 4>
By holding the sintered product of the titanium fiber nonwoven fabric used in Example 1 on a hot plate at 300 ° C. for 2 hours, an oxide film having a thickness of about 1 μm was formed on the surface of the titanium fiber, and then a width of about 30 mm, The fuel transport member 61 was produced by cutting to a length of about 60 mm. A fuel transport member D with a gas permeable layer was produced in the same manner as in Example 1 except that this fuel transport member was used, and the fuel transport member D with a gas permeable layer was used in the same manner as in Example 1 except that the fuel transport member D with a gas permeable layer was used. A fuel cell having the same configuration as the fuel cell shown in FIG. 11 was produced.

<Example 5>
A pulp-based non-woven fabric (pigment sheet SF1) having a thickness of 1 mm, a basis weight of 200 g / m ² , a porosity of 70%, and a pore diameter of 50 μm is prepared, and this is cut into a width of about 30 mm and a length of about 60 mm. did. In addition, a polyvinylidene fluoride membrane filter (hydrophilic durapore, manufactured by Millipore), which is a porous body having a pore diameter of 0.1 μm, a film thickness of 125 μm, and a porosity of 85%, is also prepared. Two gas-permeable layers 62 were produced by cutting to 60 mm. Next, after applying a hot melt agent (PPET1600, manufactured by Toa Gosei Co., Ltd.) on one whole surface of the two gas permeable layers 62 so as to have a thickness of about 5 μm by using a bar coating method, a fuel transport member After the gas permeable layers 62 are superimposed on both surfaces of 61 so that their centers are completely coincident and the application surface of the hot melt agent is on the fuel transport member 61 side, a stainless steel having a thickness of 0.5 mm is obtained. The fuel transport member 61 and the gas permeable layer 62 were thermocompression bonded by a hot press (100 ° C., 5 kN) while preventing the fuel transport member 61 from being completely crushed by using a gap gauge made of. The obtained laminate was cut into a width of 18 mm and a length of 50 mm to produce a fuel transporting member 61 (a fuel transporting member E with a gas permeable layer) having a thickness of 0.5 mm and coated on both sides with a gas permeable layer 62. . Next, a fuel cell having the same configuration as the fuel cell shown in FIG. 11 was produced in the same manner as in Example 1 except that the gas transport layer-equipped fuel transport member E was used. Note that the layer of the hot melt agent also belongs to the gas permeable layer. Therefore, the gas permeable layer included in the fuel transport member E with the gas permeable layer has a two-layer structure.

<Comparative Example 1>
FIG. 14 shows the same manner as in Example 1 except that a fuel transport member that does not have the gas permeable layer 62 (the material and size of the fuel transport member is the same as that used in Example 1) is used. A fuel cell 1400 was produced.

(Fuel cell performance evaluation)
(1) Measurement of Open Circuit Voltage and Current Density of Fuel Cell After the fuel cells of Examples 1 to 5 and Comparative Example 1 were filled with a 15 mol / L aqueous methanol solution in the fuel chamber, the fuel cell was operated for 60 seconds. The subsequent open circuit voltage and the current density obtained at a voltage of 0.2V were measured. The results are shown in Table 1. In Table 1, the numerical value “<10” of Comparative Example 1 indicates the lower resolution limit of the apparatus. That is, the current density of the fuel cell of Comparative Example 1 at a voltage of 0.2 V could not be evaluated as the current density continued to decrease with time.

(2) Evaluation of dependency of current density on length of fuel electrode and air electrode In Examples 1 to 3 and Comparative Example 1, fuel cells in which the lengths of the fuel electrode 11 and the air electrode 12 were changed were produced, and the voltage was 0. The dependence of the current density obtained at 2 V on the length of the fuel electrode and the air electrode was evaluated. The results are shown in FIG. The lengths of the fuel electrode 11 and the air electrode 12 of the fuel cells of Examples 1 to 3 and Comparative Example 1 are both 45 mm, and this length is increased or decreased from 10 mm to a maximum of 70 mm (for Comparative Example 1). Thus, a fuel cell was manufactured in which the lengths of the fuel electrode 11 and the air electrode 12 were changed. The length of the fuel electrode 11 and the length of the air electrode 12 are the same in any fuel cell after the change, and in the fuel cell in which the lengths of the fuel electrode 11 and the air electrode 12 are changed, the fuel electrode 11 The length of the fuel transport member with a gas permeable layer (in the comparative example, the fuel transport member) was increased or decreased by the same amount as the length of the air electrode 12.

  The fuel cells of Examples 1 to 5 including the gas permeable layer have a higher open circuit voltage after 60 seconds than the fuel cell of Comparative Example 1 having no gas permeable layer. It is excellent in speed and means that the time from the start of the fuel cell until the power is taken out is shorter. In particular, the fuel cell of Example 4 using a sintered product of a titanium fiber non-woven fabric having an oxide film formed on the fiber surface as the fuel transport member 61 is 60 seconds as compared with the fuel cell of Example 1 having no oxide film. The later open circuit voltage is high and better at sucking speed. Further, in the fuel cell of Comparative Example 1 having no gas permeable layer, the current density suddenly decreases when the lengths of the fuel electrode 11 and the air electrode 12 approach 40 mm, whereas the fuels of Examples 1 to 3 In the battery, a current could be obtained even when the lengths of the fuel electrode 11 and the air electrode 12 were 40 mm or more. In particular, in the fuel cell of Example 1, even if the length was increased to 70 mm, no extreme decrease in current density observed in the fuel cell of Comparative Example 1 was observed. This is because, by forming the gas permeable layer, in particular, by providing the gas permeable layer on the surface of the fuel transporting member facing the fuel electrode and on the opposite surface, the liquid fuel sucking height and This means that the suction speed is significantly improved.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 10 Electrolyte membrane, 11 Fuel electrode, 12 Air electrode, 20 Membrane electrode composite, 21 Anode current collection layer, 22 Cathode current collection layer, 30 Unit battery cell, 40 Box housing, 50 Cover housing, 51 Opening, 60 Fuel supply chamber 61 fuel transport member, 62 gas permeable layer, 62a first gas permeable layer, 62b second gas permeable layer, 63 first aperture, 70 fuel storage chamber, 71 second aperture, 100, 800, 900, 1000, 1100, 1400 Fuel cells.

Claims (13)

A unit battery cell comprising a membrane electrode assembly formed by laminating a fuel electrode, an electrolyte membrane and an air electrode in this order;
A fuel supply chamber comprising a space disposed below the fuel electrode and having the fuel electrode side open;
A fuel storage chamber for holding liquid fuel supplied to the fuel electrode;
A member made of a material exhibiting a capillary action with respect to the liquid fuel, one end of which is disposed at a position capable of contacting the liquid fuel held in the fuel storage chamber, and the other end thereof is the fuel supply chamber A fuel transport member disposed inside and extending to face the fuel electrode;
Including
The fuel transport member includes a gas permeable layer that covers at least a part of a surface of the fuel transport member and allows a vapor of the liquid fuel to pass therethrough. The fuel supply chamber includes a first opening that communicates the interior thereof with the interior of the fuel storage chamber, or communicates the interior thereof with the outside of the fuel cell.
2. The fuel cell according to claim 1, wherein the fuel storage chamber includes a second opening that communicates the inside with the outside of the fuel cell.   The fuel cell according to claim 1, wherein the gas permeable layer covers a surface of the fuel transport member facing the fuel electrode.   The fuel cell according to claim 3, wherein the gas permeable layer further covers a surface of the fuel transporting member opposite to a surface facing the fuel electrode.   The fuel cell according to claim 1, wherein the gas permeable layer is formed of a porous resin layer having pores having a pore diameter of 0.01 to 10 μm.   The fuel cell according to claim 1, wherein the gas permeable layer has a stacked structure of two or more layers.   The fuel cell according to any one of claims 1 to 6, wherein the fuel transport member is made of a metal porous body that exhibits a capillary action with respect to the liquid fuel.   The fuel cell according to claim 7, wherein the metal porous body is made of a sintered body of a metal fiber nonwoven fabric in which a fiber surface is coated with an oxide film. The fuel storage chamber is disposed on a side of the unit battery cell and a fuel supply chamber disposed below the unit battery cell,
The fuel transport member is disposed at a position where one end of the fuel transport member can contact the liquid fuel held in the fuel storage chamber, and the other end of the fuel electrode is an end of the fuel electrode opposite to the fuel storage chamber side. The fuel cell according to any one of claims 1 to 8, which is disposed at a position substantially below. The fuel supply chamber includes a first opening that communicates the inside with the outside of the fuel cell;
The fuel cell according to claim 1, wherein the first opening is disposed in the vicinity of the other end of the fuel transport member.   The fuel cell according to claim 1, wherein the unit battery cell further includes an anode current collecting layer laminated on the fuel electrode and a cathode current collecting layer laminated on the air electrode.   The fuel cell according to any one of claims 1 to 11, comprising two or more unit battery cells.   The fuel cell according to claim 12, comprising two or more fuel transport members arranged to face each of the two or more unit battery cells.

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