JP2008140658A - Fuel cell - Google Patents

Abstract

In a fuel cell having a hollow cell, gas diffusivity is improved while maintaining a current collecting property by securing a contact area of the current collector with the hollow cell.
SOLUTION: A hollow electrolyte membrane, a pair of electrodes provided on an inner peripheral surface and an outer peripheral surface of the hollow electrolyte membrane, and a current collector connected to each of the pair of electrodes, and at least one end portion is provided A fuel cell comprising an open hollow cell,
Two or more rows of linear current collectors having a flat cross section perpendicular to their own axis are parallel to each other on at least one of the inner and outer surfaces of the hollow cell. The fuel cell is arranged so that the major axis direction of the cross section extending in a direction perpendicular to its own axis is oriented with an angle in the range of 0 to 45 degrees with respect to the normal to the electrode surface.
[Selection] Figure 2

Description

  The present invention relates to a fuel cell including a hollow cell having a hollow electrolyte membrane.

  A fuel cell directly converts chemical energy into electrical energy by supplying fuel and an oxidant to two electrically connected electrodes and causing the fuel to be oxidized electrochemically. Unlike thermal power generation, fuel cells are not subject to the Carnot cycle and thus exhibit high energy conversion efficiency. Solid polymer electrolyte fuel cells using a solid polymer electrolyte as an electrolyte have advantages such as easy miniaturization and operation at a low temperature. Has been.

In the solid polymer electrolyte fuel cell, when hydrogen is used as the fuel, the reaction of the formula (1) proceeds at the anode (hydrogen electrode).
H ₂ → 2H ⁺ + 2e ⁻ (1)
The electrons generated by the equation (1) reach the cathode (oxidant electrode) after working with an external load via an external circuit. The proton generated in the formula (1) moves in the solid polymer electrolyte membrane from the hydrogen electrode side to the oxidant electrode side by electroosmosis while being hydrated with water.

Further, when oxygen is used as the oxidizing agent, the reaction of the formula (2) proceeds at the oxidizing agent electrode.
2H ⁺ + (1/2) O ₂ + 2e ⁻ → H ₂ O (2)
The water produced at the oxidizer electrode mainly passes through the gas diffusion layer and is discharged to the outside.
As described above, the fuel cell is a clean power generation device that has no emissions other than water.

Conventionally, as a solid polymer electrolyte fuel cell, a catalyst layer serving as a hydrogen electrode and an oxidant electrode is provided on one surface of a planar solid polymer electrolyte membrane and the obtained planar membrane / Flat single cells have been developed in which gas diffusion layers are further provided on both sides of the electrode assembly and sandwiched between flat separators. A plurality of such flat single cells are stacked and used as a fuel cell stack.
In order to improve the output density of the solid polymer electrolyte fuel cell, a proton conductive polymer membrane having a very thin film thickness is used as the solid polymer electrolyte membrane. This film thickness is already 100 μm or less, and even if a thinner electrolyte membrane is used to further improve the power density, the thickness of the single cell cannot be dramatically reduced from the present one. Similarly, the catalyst layer, the gas diffusion layer, the separator, and the like have been made thinner, but there is a limit to improving the output density per unit volume even by making all these members thinner. Therefore, it is expected that it will not be possible to meet the demand for miniaturization in the future.

Moreover, the sheet-like carbon material excellent in corrosivity is normally used for the said separator. In the separator, the carbon material itself is expensive, and a gas channel groove for uniformly distributing the fuel gas and the oxidant gas over the entire surface of the planar membrane / electrode assembly is formed by micromachining. Therefore, it has become very expensive. As a result, the manufacturing cost of the fuel cell was pushed up.
In addition to the above problems, for flat single cells, the periphery of single cells stacked in multiple layers should be reliably sealed so that fuel gas and oxidant gas do not leak from the gas flow path. However, there are a number of problems such as technical difficulties and a decrease in power generation efficiency due to deflection and deformation of the planar membrane / electrode assembly.

In recent years, a solid polymer electrolyte fuel cell has been developed in which a hollow cell in which electrodes are respectively provided on an inner peripheral surface side and an outer peripheral surface side of a hollow electrolyte membrane is used as a basic power generation unit (for example, Patent Documents). 1).
Since the fuel cell having such a hollow cell has a gas flow path in the hollow, a member corresponding to a separator used in a flat type is not necessary. Since different types of gas are supplied to the inner peripheral surface and the outer peripheral surface for power generation, it is not necessary to form a gas flow path. Therefore, cost reduction is expected in the manufacture. Further, since the cell has a three-dimensional shape, the specific surface area with respect to the volume can be increased as compared with the flat single cell, and the power generation output density per volume can be expected to be improved.

In a fuel cell including a hollow cell, a reaction gas (for example, hydrogen as a fuel gas here is used as a fuel gas in the hollow cell), but the oxidant gas such as air is not limited thereto. May be generated) and a reaction gas (for example, air here but may be a fuel gas such as hydrogen) flowing through the outer peripheral surface of the hollow cell reacts to generate electric power. .
Usually, in order to obtain a large voltage, first, a plurality of hollow cells are connected in parallel. In order to obtain a large current, a plurality of hollow cell stacks in which hollow cells are connected in parallel are further connected in series.
The hollow cell has current collectors (internal current collector and external current collector) connected to electrodes provided on the inner surface and the outer surface of the hollow electrolyte membrane, and the current of each cell is taken out therefrom. When a plurality of hollow cells are connected in parallel, the current of the inner surface side electrode and the current of the outer surface side electrode of each cell are collected. Patent Document 2 discloses a membrane electrode assembly for a tube-type fuel cell including a coil-shaped current collector disposed on the outer peripheral surface or inner peripheral surface of a catalyst electrode layer. Patent Document 3 discloses a hydrogen fuel cell including a conductive winding, an electrolyte membrane, and a conductive winding in this order on the outside of a hollow member.
Usually, as the linear current collector, one having a substantially circular cross section perpendicular to the axis of the current collector is used, and such current collectors are in a hollow type with two or more rows and at an equal pitch while keeping a distance between them. It is arranged on the inner peripheral surface and / or outer peripheral surface of the cell. The current collecting effect can be improved by increasing the contact area of the current collecting material on the surface of the hollow electrode by densely arranging the linear current collecting material on the inner peripheral surface and / or the outer peripheral surface of the hollow cell. However, by arranging the linear current collectors closely, the distance between the adjacent current collectors is narrow, so that the current collector inhibits the supply of the reaction gas to the electrode surface, and the electrode surface There is a risk that the gas diffusibility to the water will deteriorate. When the gas diffusibility is lowered, the concentration overvoltage is increased, and the battery performance may be lowered.

JP-T-2004-505417 JP 2005-353484 A US Pat. No. 5,458,989

  The present invention has been accomplished in view of the above circumstances, and in a fuel cell equipped with a hollow cell, while ensuring the contact area of the current collector with the hollow cell and maintaining the current collecting property, the gas diffusibility is achieved. It aims at improving.

  The purpose of the above is to make the cross section perpendicular to the own axis of the current collector a flat shape instead of the conventional perfect circle, so that the long axis of the flat shape is as perpendicular as possible to the surface of the electrode (hollow cell) This is achieved by arranging the current collector.

A fuel cell according to a first invention has a hollow electrolyte membrane, a pair of electrodes provided on an inner peripheral surface and an outer peripheral surface of the hollow electrolyte membrane, and a current collector connected to the pair of electrodes, and A fuel cell comprising a hollow cell having at least one end opened,
Two or more rows of linear current collectors having a flat cross section perpendicular to their own axis are parallel to each other on at least one of the inner and outer surfaces of the hollow cell. The major axis direction of the cross section extending and perpendicular to its own axis is oriented with an angle in the range of 0 to 45 degrees with respect to the normal to the electrode surface.

  The linear current collector having a flat cross section may be wound around the outer peripheral surface of the hollow cell.

  Further, the linear current collector having a flat cross section may be spirally wound around the outer peripheral surface of the hollow cell.

A fuel cell according to a second invention has a hollow electrolyte membrane, a pair of electrodes provided on an inner peripheral surface and an outer peripheral surface of the hollow electrolyte membrane, and a current collector connected to the pair of electrodes, and A fuel cell comprising a hollow cell having at least one end opened,
Two or more rows of linear current collectors having a substantially elliptical cross section perpendicular to its own axis are formed on at least one of the inner and outer peripheral surfaces of the hollow cell, with an interval between the current collector and the adjacent cell. Arranged to extend in parallel, and
In the cross section obtained by cutting the contact portion between the linear current collector and the electrode in a direction perpendicular to the own axis of the linear current collector, the outer periphery of the substantially elliptical cross section perpendicular to the own axis of the linear current collector and the electrode When a tangent line of the boundary line representing the electrode surface at the contact point with the boundary line representing the surface is drawn, and two perpendicular lines that are in contact with the outer periphery of the substantially elliptical cross section and perpendicularly intersect the tangent line are drawn, two lines are drawn. When the length of a tangent line separated by a perpendicular line is r, and the diameter of a perfect circle having the same cross-sectional area as the substantially elliptical cross section of the linear current collector is R,
Following formula (1):
R> r (1)
The linear current collector is oriented with respect to the electrode surface so as to satisfy the above.

  The linear current collector having a substantially elliptical cross section may be wound around the outer peripheral surface of the hollow cell.

  Furthermore, the linear current collector having a substantially elliptical cross section may be spirally wound around the outer peripheral surface of the hollow cell.

  Further, the linear current collector having the substantially elliptical cross section is oriented so that the major axis direction of the substantially elliptical cross section perpendicular to its own axis is in the range of 0 to 45 degrees with respect to the normal to the electrode surface. May be.

  According to the present invention, on at least one of the inner peripheral surface side and the outer peripheral surface side of the hollow cell, the linear current collector having a flat cross section perpendicular to its own axis, and further having a substantially elliptical shape, The current collector is arranged in such a manner that the major axis direction of the cross section perpendicular to its own axis is as perpendicular as possible to the electrode surface as long as it extends in parallel with two or more rows with a distance from the next. It is possible to increase the gap between the current collectors while ensuring the current collecting property by contacting the current. Therefore, the gas diffusibility of the reaction gas (fuel gas and oxidant gas) can be improved without hindering the diffusion of the reaction gas to the electrode surface, and the power generation performance can be improved.

  In the fuel cell of the present invention, the cross section perpendicular to its own axis of the current collector is made flat instead of the conventional perfect circle, and the long axis of the flat shape is as perpendicular as possible to the surface of the electrode (hollow cell). Thus, based on the feature of arranging the current collector, it can be understood as the first invention and the second invention. According to the first and second aspects of the present invention, the current collector is in contact with the electrode to ensure the current collecting property, and the shape of the current collecting material is prevented from inhibiting the diffusion of the reaction gas with respect to the electrode surface. Can be improved.

A fuel cell according to a first invention has a hollow electrolyte membrane, a pair of electrodes provided on an inner peripheral surface and an outer peripheral surface of the hollow electrolyte membrane, and a current collector connected to the pair of electrodes, and A fuel cell comprising a hollow cell having at least one end opened,
Two or more rows of linear current collectors having a flat cross section perpendicular to their own axis are parallel to each other on at least one of the inner and outer surfaces of the hollow cell. The major axis direction of the cross section extending and perpendicular to its own axis is oriented with an angle in the range of 0 to 45 degrees with respect to the normal to the electrode surface.
Here, the flat shape is a shape surrounded by a continuous line such as a curved line and / or a straight line that bulges outward and / or inside, and has a major axis (major axis) and a minor axis (minor axis). What you have. For example, the flat shape includes an ellipse, a trapezoid, a rhombus, a parallelogram, and a beans shape. In the present application, the maximum length of the shape is referred to as the major axis, and when the straight line passing through the midpoint of the major axis is drawn, the length of the straight line that is divided by the intersection of the straight line and the shape. The shortest length is called the short axis. When the straight line and the shape intersect at three or more points, the major axis or minor axis is determined by the two outermost points.
As the orientation angle with respect to the normal of the electrode surface in the major axis direction of the cross section perpendicular to the self-axis, the contact portion between the linear current collector and the electrode is cut in a direction perpendicular to the self-axis of the linear current collector. When the boundary representing the electrode surface is a straight line, the angle between the major axis direction of the cross section of the linear current collector and the perpendicular to the straight line representing the electrode surface is the inclination angle. Typically, a case where a linear current collector is wound around the outer peripheral surface of the hollow electrolyte membrane perpendicular to the axial direction of the hollow electrolyte membrane is applicable.

In addition, in a cross section in which the contact portion between the linear current collector and the electrode is cut in a direction perpendicular to the axis of the linear current collector, if the boundary representing the electrode surface is a curve (arc), the linear current collector The angle between the major axis direction of the cross section of the electrical material and the perpendicular of the curve representing the electrode surface at the contact point between the cross section of the linear current collector and the curve representing the electrode surface (that is, the tangent line passing through the contact point) is the inclination angle To do. Typically, this corresponds to the case where a linear current collector is disposed on the outer peripheral surface of the hollow electrolyte membrane in parallel with the axial direction of the hollow electrolyte membrane.
The linear current collector having a flat cross section may be disposed on the outer peripheral surface and / or the inner peripheral surface of the hollow electrolyte membrane in parallel with the axial direction of the hollow electrolyte membrane. Although it may be arranged vertically, it is preferably wound around the outer peripheral surface of the hollow cell, and more preferably spirally wound, because it is relatively easy to manufacture.

A fuel cell according to a second invention has a hollow electrolyte membrane, a pair of electrodes provided on an inner peripheral surface and an outer peripheral surface of the hollow electrolyte membrane, and a current collector connected to the pair of electrodes, and A fuel cell comprising a hollow cell having at least one end opened,
Two or more rows of linear current collectors having a substantially elliptical cross section perpendicular to its own axis are formed on at least one of the inner and outer peripheral surfaces of the hollow cell, with an interval between the current collector and the adjacent cell. Arranged to extend in parallel, and
In the cross section obtained by cutting the contact portion between the linear current collector and the electrode in a direction perpendicular to the own axis of the linear current collector, the outer periphery of the substantially elliptical cross section perpendicular to the own axis of the linear current collector and the electrode When a tangent line of the boundary line representing the electrode surface at the contact point with the boundary line representing the surface is drawn, and two perpendicular lines that are in contact with the outer periphery of the substantially elliptical cross section and perpendicularly intersect the tangent line are drawn, two lines are drawn. When the length of a tangent line separated by a perpendicular line is r, and the diameter of a perfect circle having the same cross-sectional area as the substantially elliptical cross section of the linear current collector is R,
Following formula (1):
R> r (1)
The linear current collector is oriented with respect to the electrode surface so as to satisfy the above.
Here, the substantially elliptical shape is not only a mathematical ellipse but also a shape surrounded by a continuous line that swells outward in an arc shape, and has a major axis (major axis) and a minor axis (minor axis). Say.

  Similarly to the first invention, the linear current collector having a substantially elliptical cross section is also arranged on the outer peripheral surface and / or inner peripheral surface of the hollow electrolyte membrane in parallel with the axial direction of the hollow electrolyte membrane. May be arranged perpendicular to the axial direction of the hollow electrolyte membrane, but since it is relatively easy to manufacture, it is preferably wound around the outer peripheral surface of the hollow cell, and wound in a spiral shape. More preferably.

Hereinafter, a representative embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to this.
A typical embodiment of the present invention shown in FIG. 1 has a hollow electrolyte membrane, a pair of electrodes provided on the inner and outer peripheral surfaces of the hollow electrolyte membrane, and a current collector connected to the pair of electrodes, respectively. In addition, the fuel cell includes a hollow cell 1 having at least one open end, and a cross section perpendicular to its own axis is substantially elliptical on the electrode on the outer peripheral surface side of the hollow cell 1. A linear current collector 2 having a spiral shape is wound around the adjacent current collector 2.

The linear current collector 2 is formed of the same material as the current collector normally used for hollow cells described later, and has a long cross section perpendicular to its own axis, preferably a substantially elliptical shape. It is a current collector and is used as at least a part of the current collector on the inner peripheral surface or outer peripheral surface of the hollow electrolyte membrane constituting the hollow cell.
The aspect ratio of the major axis to the minor axis in the substantially elliptical shape is 1.1: 1 to 5: 1, preferably 1.2: 1 to 2: 1, more preferably 1.4: 1 to 1.8: 1. It is. Further, the length of the linear current collector 2 is arbitrary depending on the length and outer periphery of the hollow cell 1 to be used.
Since the reaction gas passes between the linear current collectors 2 and comes into contact with the electrodes and is used for an electrochemical reaction, the linear current collectors 2 are spaced apart from each other, that is, arranged in a non-contact state. ing. On the other hand, in order to improve the current collection efficiency, it is desirable to wind the linear current collector densely around the hollow cell. Since the linear current collector 2 is easy to produce, typically, as shown in FIG. 1, the intervals between the linear current collectors 2 are substantially uniform, and the angle is nearly perpendicular to the axial direction of the hollow cell 1. Placed and rolled. In consideration of such a balance between gas diffusibility and current collection efficiency, the ratio of the covering area (contact area) on the inner peripheral surface and / or outer peripheral surface of the hollow cell is 5: 1 to 1: 1. The ratio is preferably 3: 1 to 1: 1, and more preferably 1: 1. Here, the covered area refers to the area of the outer peripheral surface or inner peripheral surface of the hollow cell that the linear current collector is in contact with and covers, and thus the area where the reaction gas cannot permeate, and the ratio of the covered area is The ratio of the coating area per unit area in the inner peripheral surface and / or outer peripheral surface of the hollow cell in which the linear current collector of the present invention is used.

In addition to FIG. 1 described above, a typical embodiment of the present invention has a contact portion between the linear current collector 2 and the electrode (hollow cell 1) as shown in FIG. In the cross section cut in the direction perpendicular to the own axis of the electric material 2, the electrode surface at the contact point 4 between the outer periphery of the substantially elliptical section perpendicular to the own axis of the linear current collector 2 and the boundary line 3 representing the electrode surface is shown. When the tangent line 5 of the boundary line 3 to be drawn is drawn, and two perpendicular lines 6a and 6b that are in contact with the outer periphery of the substantially elliptical cross section of the linear current collector 2 and perpendicularly intersect the tangent line 5 are drawn, When the length of the tangent line 5 separated by the perpendiculars 6a and 6b is r, and the diameter of the perfect circle 7 having the same cross-sectional area as the substantially elliptical cross section of the linear current collector is R,
Following formula (1):
R> r (1)
In this embodiment, the linear current collector 2 is oriented with respect to the surface of the electrode (hollow cell 1) so as to satisfy the above.

Here, as described above, since the linear current collector 2 is wound substantially perpendicular to the axial direction of the hollow cell, in a cross section cut in a direction perpendicular to the own axis of the linear current collector 2 As shown in FIG. 2, the boundary line 3 representing the surface of the hollow cell 1 is a straight line, the outer periphery of a substantially elliptical cross section perpendicular to the own axis of the linear current collector 2, and the hollow cell 1. The tangent line 5 of the boundary line 3 representing the surface of the hollow cell 1 at the contact point 4 with the boundary line 3 representing the surface of the surface, that is, the tangent line 5 passing through the contact point 4 is regarded as the tangent line itself.
On the other hand, when the linear current collector 2 is not wound substantially perpendicularly to the axial direction of the hollow cell, the hollow cell is cut in the cross section cut perpendicularly to the own axis of the linear current collector 2. The boundary line 3 representing the surface of 1 (electrode) is a curve, the outer periphery of a substantially elliptical cross section perpendicular to the axis of the linear current collector 2, and the boundary line 3 representing the surface of the hollow cell 1 (electrode) The tangent line 5 of the boundary line 3 representing the electrode surface at the contact point 4 is expressed as a straight line different from the boundary line 3 (FIG. 7 described later). In the case where the linear current collector 2 is not wound substantially perpendicularly to the axial direction of the hollow cell, the linear current collector 2 is wound at an angle with respect to the axial direction of the hollow cell at a more angle than the perpendicular. In this case, there is a case where the linear current collector 2 is arranged in parallel to the axial direction of the hollow cell (FIG. 6 described later).

Formula (1) shows that the major axis of the substantially elliptical shape is greatly inclined with respect to the tangent 5, that is, the orientation angle is large, and the length r of the tangent 5 separated by the perpendiculars 6 a and 6 b is larger than the diameter R of the perfect circle 7. It means not to grow up.
When the linear current collector 2 of the present invention is wound as shown in FIG. 1, the current collector is a perfect circle 7 having a cross section perpendicular to its own axis and the same cross-sectional area as the linear current collector 2 of the present invention ( Compared with the case where the virtual current collector is hereinafter wound around the same position as the linear current collector 2 of the present invention, as shown in FIG. 2, the linear current collector of the present invention is more preferable than the virtual current collector. However, the gap between the linear current collectors is large. Therefore, the reactive gas flows between the current collectors and easily comes into contact with the electrode surface, and the gas diffusibility is high. Here, since the cross-sectional areas of the virtual current collector and the linear current collector of the present invention are the same, the electrical conductivity is the same. Further, since both the virtual current collector and the linear current collector of the present invention are in contact with the electrode on the outer peripheral surface of the hollow cell 1 at the contact point 4, current can be collected in the same manner.
For this reason, the linear current collector of the present invention has a substantially elliptical cross section perpendicular to its own axis. Therefore, the major axis of the substantially elliptical shape of the cross section of the linear current collector 2 is slightly inclined with respect to the tangent 5. However, in order to increase the gap between the linear current collectors, the major axis direction of the ellipse is as long as possible with respect to the electrode surface, that is, as described above, in the present embodiment. Is preferably placed upright with respect to the tangent 5. Therefore, r is ideally the same as the minor axis of the substantially elliptical shape.

Specifically, as shown in FIG. 3, the linear current collector having a substantially elliptical cross section has a major axis direction 8 of a substantially elliptical cross section perpendicular to its own axis. ) With respect to the vertical line 9 in the range of 0 to 45 degrees (tilt angle θ). More preferably, it is in the range of 0 ° to 30 °, more preferably 0 ° to 10 °. When the above range is exceeded, it is difficult to improve gas diffusibility, and it is difficult to maintain the orientation angle of the linear current collector.
In the embodiment shown in FIGS. 1 and 2, the linear current collector 2 of the present invention is wound around the outer peripheral surface of the hollow cell 1, but the linear current collector 2 of the present invention is wound around the hollow cell 1. It may be arranged on the inner peripheral surface side.

The linear current collector 2 is in contact with the electrode surface on the upstream side and the downstream side of the hollow cell when a power generation gradient exists such that the upstream side of the hollow cell has a higher concentration of reaction gas than the downstream side. A difference may be provided in the aspect ratio of the cross section perpendicular to the own axis of the linear current collector.
In the state where the pitch of the linear conductive material is uniform as in this embodiment, a difference is provided in the aspect ratio of the cross section between the upstream side and the downstream side of the hollow cell, and the gap between the linear conductive materials is adjusted. Thus, the degree to which the reaction gas contacts the surface of the hollow cell can be adjusted on the upstream side and the downstream side of the hollow cell. As such a form, for example, a current collector having a perfect circle (aspect ratio 1) perpendicular to its own axis is disposed on the upstream side in the axial direction of the hollow cell, and the present invention is disposed on the downstream side. A configuration in which a current collector having a substantially elliptical cross section perpendicular to its own axis is disposed, and a current collector having a relatively large inclination angle is disposed on the upstream side in the axial direction of the hollow cell, and the current collector is disposed on the downstream side. The form which arrange | positions the current collector with a comparatively small angle | corner, these combinations, etc. are mentioned. When the pitch of the linear current collector is made uniform and the cross-sectional area of the linear conductive material is equal, the current collecting performance per unit area is the same on the upstream side and the downstream side of the hollow cell.
In addition to the adjustment of the gap between the linear current collectors described above, on the upstream side and the downstream side of the hollow cell, the pitch of the linear conductive material is changed to adjust the coverage area of the electrode surface with the linear current collector, and the reaction gas It is also possible to adjust the degree of contact of the surface of the hollow cell with the upstream side and the downstream side of the hollow cell. Examples of such a form include a form in which a linear current collector is tightly wound on the upstream side of the hollow cell and the linear current collector is roughly wound on the downstream side. Since the pitch of the linear current collector is changed, it is possible to cause a difference in the current collecting performance per unit area between the upstream side and the downstream side of the hollow cell.

Hereinafter, the hollow cell 1 provided in the fuel cell of the present invention will be described with reference to FIGS. Although not shown in FIGS. 4 and 5, as described above, the linear current collector 2 is formed of the same material as the current collector normally used in a hollow cell described later, and is It is a long current collector having a substantially elliptical cross section perpendicular to the axis, and is used as at least a part of the current collector on the inner or outer peripheral surface of the hollow electrolyte membrane constituting the hollow cell.
FIG. 4 is a perspective view showing an example of a hollow cell provided in the fuel cell of the present invention, and FIG. 5 is a schematic cross-sectional view of the hollow cell of FIG. 4 and 5, a hollow cell 1 includes a tubular solid polymer electrolyte membrane (perfluorocarbon sulfonic acid resin membrane) 11 and an anode provided on the inner peripheral surface side of the solid polymer electrolyte membrane 11 (this embodiment). , The fuel electrode 12 and the cathode (air electrode in this embodiment) 13 provided on the outer peripheral surface side. Further, a columnar current collector is disposed on the surface of the anode 12 as the anode-side current collector 14, and a net-like (net-shaped) current collector 15 a made of metal wire and a rod-shaped current collector are disposed on the surface of the cathode 13 as the cathode current collector 15. An electric material 15b is arranged.
On the hollow inner peripheral surface of the hollow cell having such a structure (substantially the portion exposed to the inner peripheral surface side gas flow path formed by the groove 14a provided on the outer peripheral surface of the anode current collector 14). By supplying hydrogen gas and air to the outer peripheral surface, fuel or an oxidant is supplied to the anode and cathode to generate electricity.

  The hollow cell 1 of FIG. 4 has hollow portions open at both ends, and the fuel gas flows from one end into the hollow and flows out from the other end. As long as the hollow cell 1 can sufficiently supply the reaction gas to the inner peripheral surface side of the hollow electrolyte membrane, only one end of the hollow portion may be opened and the other end may be sealed. In particular, when a fuel electrode using hydrogen as a fuel is provided as an electrode on the inner peripheral surface side as in this embodiment, hydrogen gas containing almost no non-reactive component is supplied into the hollow of the hollow cell as a fuel gas. In addition, since the diffusibility of hydrogen molecules is high, it is possible to consume the reaction gas supplied in the hollow, so that the reaction gas can be sufficiently supplied even in the hollow portion where one end is sealed. Can do. Examples of the method of sealing one end of the hollow cell include a method of injecting resin or the like into the hollow one end, but is not particularly limited.

  In FIG. 4, the hollow cell 1 has a tubular electrolyte membrane, but the hollow electrolyte membrane in the present invention is not limited to a tubular shape, has a hollow portion, and a fuel or an oxidant flows into the hollow portion. By doing so, it is only necessary that the reaction component necessary for the electrochemical reaction can be supplied to the electrode provided in the hollow interior.

  The inner diameter, outer diameter, length, etc. of the tubular solid polymer electrolyte membrane 11 are not particularly limited, but the outer diameter of the tubular electrolyte membrane is preferably 0.01 to 10 mm, 0.1 More preferably, it is-1 mm, and it is especially preferable that it is 0.1-0.5 mm. At present, it is difficult to manufacture a tubular electrolyte membrane having an outer diameter of less than 0.01 mm due to technical problems. On the other hand, when the outer diameter exceeds 10 mm, the surface area relative to the occupied volume is not so large. The output per unit volume of the obtained hollow cell may not be sufficiently obtained.

The perfluorocarbon sulfonic acid resin membrane is preferably thin from the viewpoint of improving proton conductivity, but if it is too thin, the function of isolating gas is lowered and the permeation amount of aprotic hydrogen is increased. However, compared to conventional fuel cells in which flat single cells for fuel cells are stacked, a fuel cell manufactured by collecting a large number of cells having a hollow shape can take a large electrode area, so a slightly thicker membrane is formed. Even when used, a sufficient output can be obtained. From this viewpoint, the thickness of the perfluorocarbon sulfonic acid resin film is 10 to 100 μm, more preferably 50 to 60 μm, and still more preferably 50 to 55 μm.
Moreover, from the preferable range of said outer diameter and film thickness, the preferable range of an internal diameter is 0.01-10 mm, More preferably, it is 0.1-1 mm, More preferably, it is 0.1-0.5 mm. is there.

Since the fuel cell of the present invention has a hollow cell, the electrode area per unit volume can be made larger than that of a fuel cell having a flat cell. Therefore, as the solid polymer electrolyte membrane, perfluorocarbon sulfonic acid is used. Even when an electrolyte membrane that does not have a proton conductivity as high as that of a resin membrane is used, a fuel cell having a high output density per unit volume can be obtained.
As the solid polymer electrolyte membrane, perfluorocarbon sulfonic acid resin and materials used for the electrolyte membrane of solid polymer fuel cells can be used. For example, fluorine other than perfluorocarbon sulfonic acid resin can be used. One kind of proton exchange groups such as at least sulfonic acid groups, phosphonic acid groups, and phosphoric acid groups, based on hydrocarbons such as polyolefins such as polystyrene ion exchange resins and polystyrene cation exchange membranes having sulfonic acid groups A complex of a basic polymer and a strong acid, which is disclosed in Japanese Patent Application Laid-Open No. 11-503262, etc., in which a basic polymer such as polybenzimidazole, polypyrimidine, and polybenzoxazole is doped with a strong acid And polymer electrolytes such as solid polymer electrolytes.

  A solid polymer electrolyte membrane using such an electrolyte should be reinforced with a perfluorocarbon polymer in the form of a fibril, a fabric, a non-fabric, or a porous sheet, or the membrane surface can be coated with an inorganic oxide or metal. It can also be reinforced. In addition, examples of the perfluorocarbon sulfonic acid resin membrane include commercially available products such as Nafion manufactured by DuPont and Flemion manufactured by Asahi Glass.

In the present embodiment, a perfluorocarbon sulfonic acid resin membrane, which is a kind of proton conducting membrane and one of solid polymer electrolyte membranes, is described as an electrolyte membrane, but it is used in the fuel cell of the present invention. The electrolyte membrane to be used is not particularly limited, and may be proton-conductive or other ion-conductive such as hydroxide ion or oxide ion (O ²⁻ ). The proton conductive electrolyte membrane is not limited to the solid polymer electrolyte membrane as described above, but a porous electrolyte plate impregnated with an aqueous phosphoric acid solution, a proton conductor made of porous glass, or a hydrogel Phosphated phosphate glass, organic-inorganic hybrid proton conductive membrane having proton conductive functional groups introduced into the surface and pores of nanoporous glass, inorganic metal fiber reinforced electrolyte polymer, etc. can be used. .

  The electrodes 12 and 13 provided on the inner peripheral surface and the outer peripheral surface of the electrolyte membrane 11 can be formed using an electrode material as used in a polymer electrolyte fuel cell. Usually, an electrode configured by laminating a catalyst layer and a gas diffusion layer in order from the electrolyte membrane side is used.

The catalyst layer includes catalyst particles, and may further include a proton conductive material for increasing the utilization efficiency of the catalyst particles. As the proton conductive material, those used as the material for the electrolyte membrane can be used. As the catalyst particles, catalyst particles in which a catalyst component is supported on a conductive material such as a carbon material such as carbonaceous particles or carbonaceous fibers are preferably used.
Since the fuel cell of the present invention has a hollow cell, the electrode area per unit volume can be made larger than that of a fuel cell having a flat cell. Therefore, a catalyst component that is not as catalytic as platinum is used. However, a fuel cell having a high output density per unit volume can be obtained.

  The catalyst component is not particularly limited as long as it has a catalytic action for hydrogen oxidation reaction at the anode and oxygen reduction reaction at the cathode. For example, platinum (Pt), ruthenium (Ru), iridium (Ir) , Rhodium (Rh), palladium (Pd), osmium (Os), tungsten (W), lead (Pb), iron (Fe), chromium (Cr), cobalt (Co), nickel (Ni), manganese (Mn) , Vanadium (V), molybdenum (Mo), gallium (Ga), aluminum (Al) and other metals, or alloys thereof. Pt and an alloy made of Pt and another metal such as Ru are preferable.

As the gas diffusion layer, a porous conductive material mainly composed of a carbon material such as carbonaceous particles and / or carbonaceous fibers can be used. The sizes of the carbonaceous particles and the carbonaceous fibers may be appropriately selected in consideration of the dispersibility in the solution when the gas diffusion layer is produced, the drainage property of the obtained gas diffusion layer, and the like. The gas diffusion layer is, for example, polytetrafluoroethylene, polyvinylidene fluoride (PVDF), polytetrafluoroethylene, perfluorocarbon alkoxyalkane, ethylene-tetrafluoroethylene polymer, or these from the point of improving the drainage of moisture such as generated water It is preferable to perform water-repellent processing by impregnating a mixture of the above or the like or forming a water-repellent layer using these substances.
In addition, the structure of each electrode provided in the inner peripheral surface and outer peripheral surface of a hollow electrolyte membrane, the material used for an electrode, etc. may be the same, and may differ.

  The method for providing a pair of electrodes on the inner and outer peripheral surfaces of the tubular electrolyte membrane is not particularly limited. For example, first, a tubular electrolyte membrane is prepared. The method for preparing the tubular electrolyte membrane is not particularly limited, and a commercially available electrolyte membrane formed in a tube shape can also be used. Then, a solution containing electrolyte and catalyst particles is applied and dried on the inner and outer peripheral surfaces of the tubular electrolyte membrane to form a catalyst layer, and carbonaceous particles and / or carbonaceous matter are formed on the two catalyst layers. The method of apply | coating and drying the solution containing a fiber and forming a gas diffusion layer is mentioned. At this time, the catalyst layer and the gas diffusion layer are formed so that the hollow portion exists on the inner peripheral surface of the gas diffusion layer formed on the inner peripheral surface side of the electrolyte membrane.

  Alternatively, first, a carbon material such as carbonaceous particles and / or carbonaceous fibers and formed into a tube shape (tubular carbonaceous material) is used as a gas diffusion layer of the inner peripheral surface side electrode (anode), A solution containing an electrolyte and catalyst particles is applied to the outer peripheral surface of the gas diffusion layer and dried to form a catalyst layer of the inner peripheral surface side electrode to produce the inner peripheral surface side electrode, and then the outer peripheral surface of the catalyst layer. A solution containing an electrolyte is applied and dried to form an electrolyte membrane layer, a catalyst layer of an outer peripheral surface side electrode (cathode) is formed on the outer peripheral surface of the electrolyte membrane layer, and a solution containing a carbon material on the outer peripheral surface of the catalyst layer There is also a method of forming a gas diffusion layer of the outer peripheral surface side electrode by applying and drying. The tubular carbonaceous material can be obtained, for example, by dispersing a carbon material such as carbonaceous particles and an epoxy and / or phenolic resin in a solvent to form a tubular shape, thermosetting, and firing.

In addition, the solvent used when forming the electrolyte membrane, the catalyst layer, and the gas diffusion layer may be appropriately selected according to the material to be dispersed and / or dissolved, and the coating method when forming each layer is also as follows. It can be appropriately selected from various methods such as spraying and screen printing.
The hollow cell used in the fuel cell of the present invention is not limited to the configuration exemplified above, and layers other than the catalyst layer and the gas diffusion layer may be provided for the purpose of enhancing the function of the hollow cell. In this embodiment, the anode is provided inside the hollow electrolyte membrane and the cathode is provided outside, but the cathode may be provided inside and the anode may be provided outside.

Next, the current collector that can be provided in the fuel cell of the present invention will be described. The current collector is connected to electrodes provided on the inner peripheral surface and outer peripheral surface of the hollow electrolyte membrane of the hollow cell, and takes out the current of each cell.
The current collector of the present invention is not particularly limited as long as it is made of an electrically conductive material. Examples of the metal used as the current collector include at least one metal selected from Al, Cu, Fe, Ni, Cr, Ta, Ti, Zr, Sm, In, and the like, or those such as stainless steel The alloy is preferred. Further, the surface thereof may be coated with Au, Pt, conductive resin or the like. Of these, stainless steel and titanium are preferred because of their excellent corrosion resistance.
The shape of the current collector is not particularly limited, and may be a linear shape, a cylindrical shape, or an annular shape in addition to a columnar shape, a wire shape, or a rod shape. For example, a sheet material such as a spring-shaped metal wire, metal foil, metal sheet, or carbon sheet The thing which consists of can also be applied. The thickness of the wire and the braid density, the thickness of the rod-shaped current collector, etc. are not particularly limited.

As a form of the current collector, the linear current collector of the present invention can be disposed on the inner peripheral surface and / or outer peripheral surface of the hollow cell. The current collector can be used in combination with a plurality of forms. Other typical forms of the current collector will be described below.
For example, an anode side current collector (in this embodiment, an internal current collector disposed on the inner surface side electrode surface) 14 as shown in FIG. 5 is a columnar current collector having an outer diameter in contact with the inner peripheral surface of the hollow cell 1. On the outer peripheral surface, a groove 14a extending in the axial direction (longitudinal direction) of the hollow cell 1 is formed. A gap between the groove 14a and the inner peripheral surface side electrode 12 serves as an inner peripheral gas flow path 1a (shown in FIG. 1) for supplying hydrogen gas. As the groove 14a, at least one groove extending in the axial direction (longitudinal direction) of the hollow cell 1 is necessary, and grooves having various patterns or orientations on the outer peripheral surface of the hollow cell 1 as necessary. It is formed.

  Further, as the cathode side current collector (in this embodiment, the external current collector disposed on the outer surface side electrode surface) 15, for example, as shown in FIG. 4, the hollow cell 1 and the rod-shaped current collector 15 b are arranged in parallel. A net-like current collector 15a, which is a part of the cathode-side current collector 15 in which metal wires are braided so as to cover the outer peripheral surfaces of both of them alternately arranged, is formed. The net-like current collector 15a made of a metal wire is formed so that the plurality of hollow cells 1 and the rod-shaped current collector 15b of each hollow cell are integrated, and the cathode (outer surface side electrode) and each rod of each hollow cell. Metal wires are knitted so as to contact the current collector 15b, and the mesh-like current collector 15a is shared by a plurality of hollow cells. At this time, the cathode side current collectors (15a, 15b) of the hollow cells form a connection network electrically connected to each other. However, the shape of the current collector is merely an example and is not limited thereto.

These current collectors are fixed on the electrodes with a conductive adhesive such as a carbon-based adhesive or an Ag paste as necessary.
A reactive gas blocking material or a conductive member may be interposed between the hollow cell 1 and the current collector. As the material of the conductive member, the same material as the conductive material can be used.

Next, the heat exchange member that can be provided in the fuel cell of the present invention will be described.
The heat exchange member may be any one that can be in contact with at least a partial region along the axial length of the hollow cell and can implement the present invention, but is usually a tube provided in parallel with the hollow cell. It is preferable to have one heat medium supply port and one heat medium discharge port. This is because the seal structure for fixing the heat exchange member can be simplified by using the heat exchange member having such a structure.
The heat exchange member is connected to a heat exchanger (not shown), the heat medium circulates through the heat exchanger, and the heat medium circulates through the heat exchange member. The heat medium in the heat exchange member exchanges heat with the hollow cell, and then is collected in the heat exchanger through the flow path, returned to the original heat state, supplied to the heat exchange member again, and circulated. .

The heat exchange member is formed of a material having thermal conductivity that allows the hollow cell to be cooled or heated to a predetermined temperature range when a heat medium flows through the heat exchange member. Examples of such materials include common metals such as Cu, Al, Ti, Pt, Ag, and Au, and alloys or clad materials of combinations of these metals.
The outer diameter of the cooling pipe varies depending on the size of the hollow cell and is not particularly limited, but is usually in the range of 0.5 to 2 mm.
As the heat medium, a fluid generally used as a coolant or a heat medium heater or a boiler can be used, and may be a liquid or a gas. For example, examples of the liquid include water and ethylene glycol, and examples of the gas include air. From the viewpoint of the cooling effect, a liquid coolant is usually preferable. As the liquid coolant, ethylene glycol can be preferably used from the viewpoints of convection, freezing resistance, and corrosivity. Moreover, when heating a cell, heat medium oil, sand, etc. can be used as a heat medium.
As the heat exchanger, a general heat exchanger can be used. For example, those that radiate heat by ventilation such as a cooling fan, those that radiate heat by circulating a solvent serving as a heat medium, and those that use an air-cooling system that uses air as the outside air can be used. Among these, a radiator that radiates heat in the air is preferable.

As described above, the linear current collector used in the fuel cell of the present invention is a long current collector having a flat cross section perpendicular to its own axis, more preferably a substantially elliptical shape. Such a linear current collector is arranged on the outer peripheral surface of the hollow cell as a form in which the linear current collector is arranged so as to extend in parallel with two or more rows in a non-contact state. As a typical example, a mode in which a linear current collector is spirally wound around the outer peripheral surface of a hollow cell is shown.
In the present invention, the following modifications are given.
(First modification)
In the fuel cell of the present invention, on the electrode on the outer peripheral surface side of the hollow cell, an annular current collector having a flat cross section perpendicular to its own axis extends in parallel with two or more rows with an interval between them, In addition, the embodiment may be characterized by being wound so that the major axis direction of the cross section perpendicular to its own axis is oriented at an angle within a range of 0 to 45 degrees with respect to the normal to the electrode surface. .
The form in which the linear member is wound around the hollow cell is not limited to the form wound in a spiral shape, and a plurality of annular current collectors are arranged at a desired interval in the axial direction of the hollow cell (hollow A form that fits into a mold cell is also included. When the first modification is illustrated, a perspective view similar to FIG. 1 is obtained.
The inner diameter of the annular current collector is arbitrary according to the outer diameter of the hollow cell.
The linear current collector of the present invention may be disposed on the inner peripheral surface side of the hollow cell.
(Second modification)
As a form in which the linear current collector of the present invention is arranged so as to extend in parallel with two or more rows with an interval between adjacent ones, the linear current collector is wound around the outer peripheral surface of the hollow cell described above. In addition, the following forms are also included.
In the fuel cell of the present invention, as shown in the perspective view of FIG. 6, the linear current collector 2 having a substantially elliptical cross section perpendicular to its own axis is adjacent to the electrode on the outer peripheral surface side of the hollow cell 1. Are arranged in parallel with the axial direction of the hollow cell 1 so as to extend in parallel with two or more rows with an interval between and
As shown in the partial cross-sectional view of FIG. 7, the contact portion between the linear current collector 2 and the electrode (hollow cell 1) is cut in a direction perpendicular to the axis of the linear current collector 2. The tangent 5 of the boundary line 3 representing the electrode surface at the contact point 4 between the outer periphery of the substantially elliptical section perpendicular to the axis of the linear current collector 2 and the boundary line 3 representing the electrode surface is drawn, and the substantially elliptical section When the two perpendicular lines 6a and 6b that are in contact with the outer periphery of the line and perpendicularly intersect the tangent line 5 are drawn, the length of the tangent line 5 divided by the two perpendicular lines 6a and 6b is defined as r, and the linear collection When the diameter of a perfect circle having the same cross-sectional area as the substantially elliptical cross section of the electric material 2 is R,
Following formula (1):
R> r (1)
In another embodiment, the linear current collector 2 is oriented with respect to the electrode surface so as to satisfy the above condition.
The length of the linear current collector is arbitrary together with the length of the hollow cell 1 in the axial direction.
The linear current collector may be disposed on the inner peripheral surface side of the hollow cell.

  According to the fuel cell of the present invention as described above, the cross section perpendicular to its own axis is flat, more preferably substantially elliptical, on at least one of the inner peripheral surface side and the outer peripheral surface side of the hollow cell. Are arranged so that the major axis direction of the cross section perpendicular to its own axis is as perpendicular to the electrode surface as possible as long as possible. Thus, the gap between the current collectors can be increased while the current collectors are in contact with the electrodes to ensure current collection. Therefore, the gas diffusibility of the reaction gas (fuel gas and oxidant gas) can be improved without hindering the diffusion of the reaction gas to the electrode surface, and the power generation performance can be improved.

The fuel cell of the present invention is obtained by connecting two or more cell stacks in parallel or in series, each including at least two of the above-described hollow cell, current collector and heat exchange member in parallel or in series.
Specifically, as shown in FIG. 8, the cell stack 30 includes two or more hollow cells 1, a current collector and a heat exchange member integrated product (cell module 29). At both ends of the cell stack 30, gas manifolds 31a and 31b for circulating hydrogen gas into the hollow of the hollow cell 1 and heat medium manifolds 32a and 32b for circulating a heat medium in the heat exchange member are provided. Furthermore, a current collector (not shown) that collects the charges generated in each hollow cell 1 is provided. Partition walls 35a and 35b (external restraint members described above) disposed between the hydrogen gas flow path 33 in the gas manifolds 31a and 31b and the oxidant gas flow path 34 between the gas manifolds 31a and 31b. Through holes into which the cell modules 29 can be inserted are provided at predetermined intervals, and the plurality of cell modules 29 are inserted into the through holes of the partition walls 35a and 35b facing each other. Thus, they are aligned at predetermined intervals and in parallel with each other in the longitudinal direction. The partition walls 35a and 35b are subjected to a potting process for pouring a potting material and sealing a region including the periphery of the through hole on the side of the oxidizing gas channel, and the cell module 29 inserted into the through hole is fixed integrally. Has been.
In the cell stack 30, the hydrogen supplied to the cell stack 30 via the gas manifold (for example, 31 a) on the inlet side passes through the inner peripheral surface side gas flow path 1 a of each hollow cell 1, and the oxidant The oxygen in the air supplied from the gas flow path 34 to the outer peripheral surface of the hollow cell 1 and the electrolyte membrane through the electrolyte membrane, hydrogen and the like not used in the electrochemical reaction are gas manifolds on the outlet side. (For example, 31b). In the cell stack 30, one of the current collectors is electrically connected to the negative current collector 14 shown in FIG. 4 of the hollow cell 1, and the other is the positive current collector shown in FIG. 4. By being electrically connected to 15 (15a, 15b), the charges generated in the plurality of hollow cells 1 are collected (collected).

It is a perspective view which shows embodiment in this invention. It is a partial typical sectional view showing an embodiment in the present invention. It is a partial typical sectional view showing an embodiment in the present invention. It is a perspective view which shows one example of the hollow cell with which the fuel cell of this invention is equipped. It is sectional drawing of the hollow type cell of FIG. It is a perspective view which shows the 2nd modification in this invention. It is typical sectional drawing which shows a part of 2nd modification in this invention. It is an external view which shows roughly the example of 1 form of the cell stack of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hollow cell 1a ... Inner peripheral side gas flow path 2 ... Linear current collector 3 ... Boundary line 4 ... Contact 5 ... Tangent 6a, 6b ... Perpendicular 7 ... Perfect circle 8 ... Long diameter (major axis) direction 9 ... Electrode surface Vertical line 11 ... Hollow electrolyte membrane (perfluorocarbon sulfonic acid membrane)
12 ... Anode (inner surface side electrode)
13 ... Cathode (outer peripheral surface side electrode)
14 ... Anode-side current collector (internal current collector)
14a ... Groove 15 (15a, 15b) ... Cathode side current collector (external current collector)
DESCRIPTION OF SYMBOLS 29 ... Cell module 30 ... Cell stack 31 (31a, 31b) ... Gas manifold 32 (32a, 32b) ... Heat medium manifold 33 ... Hydrogen gas flow passage 34 ... Oxidant gas flow passage 35 (35a, 35b) ... Partition

Claims (7)

A hollow electrolyte membrane, a pair of electrodes provided on an inner peripheral surface and an outer peripheral surface of the hollow electrolyte membrane, and a current collector connected to each of the pair of electrodes, and at least one end thereof being open A fuel cell comprising a type cell,
Two or more rows of linear current collectors having a flat cross section perpendicular to their own axis are parallel to each other on at least one of the inner and outer surfaces of the hollow cell. The fuel cell is arranged so that the major axis direction of the cross section extending in a direction perpendicular to its own axis is oriented with an angle in the range of 0 to 45 degrees with respect to the normal to the electrode surface.   2. The fuel cell according to claim 1, wherein the linear current collector having a flat cross section is wound around an outer peripheral surface of the hollow cell.   3. The fuel cell according to claim 2, wherein the linear current collector having a flat cross section is wound spirally around an outer peripheral surface of the hollow cell. A hollow electrolyte membrane, a pair of electrodes provided on an inner peripheral surface and an outer peripheral surface of the hollow electrolyte membrane, and a current collector connected to each of the pair of electrodes, and at least one end thereof being open A fuel cell comprising a type cell,
Two or more rows of linear current collectors having a substantially elliptical cross section perpendicular to its own axis are formed on at least one of the inner and outer peripheral surfaces of the hollow cell, with an interval between the current collector and the adjacent cell. Arranged to extend in parallel, and
In the cross section obtained by cutting the contact portion between the linear current collector and the electrode in a direction perpendicular to the own axis of the linear current collector, the outer periphery of the substantially elliptical cross section perpendicular to the own axis of the linear current collector and the electrode When a tangent line of the boundary line representing the electrode surface at the contact point with the boundary line representing the surface is drawn, and two perpendicular lines that are in contact with the outer periphery of the substantially elliptical cross section and perpendicularly intersect the tangent line are drawn, two lines are drawn. When the length of a tangent line separated by a perpendicular line is r, and the diameter of a perfect circle having the same cross-sectional area as the substantially elliptical cross section of the linear current collector is R,
Following formula (1):
R> r (1)
The fuel cell, wherein the linear current collector is oriented with respect to the electrode surface so as to satisfy   The fuel cell according to claim 4, wherein the linear current collector having a substantially elliptical cross section is wound around an outer peripheral surface of the hollow cell.   6. The fuel cell according to claim 5, wherein the linear current collector having a substantially elliptical cross section is spirally wound around an outer peripheral surface of the hollow cell.   The linear current collector having the substantially elliptical cross section is oriented so that the major axis direction of the substantially elliptical cross section perpendicular to its own axis is in the range of 0 to 45 degrees with respect to the normal to the electrode surface. The fuel cell according to claim 4, wherein:

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