JP4776224B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell having a good current collection characteristic of a plurality of fuel cells.

  In recent years, various fuel cells in which a fuel cell stack is accommodated in a storage container have been proposed as next-generation energy.

  The fuel cell stack is obtained by arranging a plurality of adjacent fuel cells electrically connected via a current collecting member in series and standing on a manifold. And as a current collection member, while ensuring the electrical connection between fuel cells reliably over a long period of time, and improving the current collection characteristics between fuel cells, a plate-like shape that can maintain elastic force for a long period of time The one that spreads the current collector piece is adopted. However, in such a fuel cell, since the electrical connection was ensured by pushing and spreading the fuel cell with a strong elastic force, the breakage of the fuel cell was promoted or the upper end of the fuel cell was changed over time. There was a tendency for the part side to spread in the arrangement direction.

In order to solve such a problem, for example, a fuel cell is known in which a rectangular frame-shaped widening prevention member is disposed as viewed from above so as to surround the vicinity of the upper end of the fuel cell stack (Patent Document). 1). There is also known a fuel cell that has a mechanism such as a spring and a screw, is supported by a fixed structure (such as an external housing of the fuel cell), and includes a pressing unit that presses the fuel cell stack (Patent Document 2). reference).
JP 2003-308857 A JP-A-8-162146

  However, in the fuel cell in which the widening prevention member described in Patent Document 1 is arranged, the spread in the arrangement direction on the upper end side of the fuel cell can be eliminated, but the fuel battery cells surrounded by the widening prevention member are inclined in the same direction. As a result, there is a problem that the current collecting member arranged at the end part may be separated from the fuel cell or the contact property may be lowered. Further, in the fuel cell having the pressing means described in Patent Document 2, for example, when a spring is used, the spring loses elasticity with the passage of a long time, and the contact property between the end current collecting member and the fuel cell decreases. When a screw is used, due to sizing regulation (gap regulation), it is impossible to follow the dimensional change of the stack, and the contact between the end current collecting member and the fuel cell is reduced like the spring. As a result, there has been a problem that the output may be lowered.

  An object of the present invention is to provide a fuel cell that is excellent in long-term reliability without deterioration in contact between the fuel cell and the end current collecting member.

  As a result of intensive studies, the present inventors have found that a constant load can be continuously applied to the fuel cell stack by utilizing the weight of the weight, and the present invention has been achieved.

That is, the present invention provides a fuel battery cell in which fuel cells and current collecting members for electrically connecting adjacent fuel cells are alternately arranged in series in one direction and are erected on a manifold. A fuel cell in which a stack is stored in a storage container, the receiving member having a first inclined surface facing obliquely upward on the fuel cell stack side, and facing the first inclined surface of the receiving member And a flat slide member having a second inclined surface at the lower end facing obliquely downward on the opposite side to the fuel cell stack, wherein the second inclined surface is the first inclined surface. When the sliding member moves downward, the pressing means for moving in the horizontal direction as it descends is provided adjacent to both sides of the fuel cell stack, and the sliding member is provided in the fuel cell cell. With comprises a fourth inclined surface and click directed obliquely upward opposite to the upper end, the said arranged above the fuel cell stack, the respective sliding members arranged on both sides of the fuel cell stack The fuel cell further comprises a frame-shaped load application member having a third inclined surface facing obliquely downward on the fuel cell stack side, which is in contact with each of the four inclined surfaces. Thus, a constant load can be continuously applied to the fuel cell stack by utilizing the weight of the weight.

Incidentally, the first one of the inclined surface and the second inclined surface of are either formed on the dimple-like over substantially the entire surface, or along the sliding direction a plurality of grooves are formed Is desirable. Or, preferably ceramic powder-like body between said first inclined surface and the second inclined surface are dispersed. Thus, it is possible to suppress the frictional force generated between the first inclined surface and the second inclined surface.

  According to the present invention, since a constant load can be applied to the fuel cell stack continuously by utilizing the dead weight of the weight, the contact property between the fuel cell and the end current collecting member is reduced. Therefore, a fuel cell having excellent long-term reliability can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 and 2 are diagrams showing an example of pressing means in the fuel cell of the present invention, and FIG. 5 shows a reference example of the fuel cell of the present invention. The fuel cell shown in FIG. 5 has fuel cells 10 and current collecting members 20 for electrically connecting adjacent fuel cells 10 alternately arranged in series and standing on a manifold 30. A fuel cell in which the fuel cell stack B is stored in a storage container, and pressing means A for preventing the fuel cell 10 from spreading in the arrangement direction is adjacent to both ends of the fuel cell stack B. The pressing means A is configured to press both ends of the fuel cell stack B by converting a load caused by the weight of the member included in the pressing means A in the horizontal direction.

  The pressing means A is composed of a pair of receiving members 11 and a slide member 21 as shown in FIG. 1 (a). As shown in FIG. 5, both ends of the fuel cell stack B (arrangement of the fuel cells 3). Are provided adjacent to each other).

  The receiving member 11 is provided with a first inclined surface 111 at a lower portion facing obliquely upward on the fuel cell stack B side in a state where it is disposed at both ends of the fuel cell stack B. Moreover, the support part 112 standingly arranged in the position which becomes a back side and both sides seeing from the fuel cell stack B is comprised. The first inclined surface 111 is formed in order to convert the load due to the weight of the slide member 21 in the horizontal direction in cooperation with a second inclined surface 211 provided at the lower end of the slide member 21 described later. It is. The support portion 112 prevents the slide member 21 (described later) from falling on the back side or the lateral direction with respect to the fuel cell stack B without pressing both ends of the fuel cell stack B. It is for supporting. Therefore, it is preferable that the space surrounded by the support portion 112 is substantially equal to the cross-sectional shape of the slide member 21.

  The slide member 21 is a flat plate-like member, and has a second inclined surface 211 that faces the first inclined surface 111 of the receiving member 11 and faces the first inclined surface 111 on the opposite side to the fuel cell stack B. It has. The second inclined surface 211 has an inclination angle substantially equal to that of the first inclined surface 111, and the second inclined surface 211 slides with respect to the first inclined surface 111, so that FIG. As shown in b), the slide member 21 moves in the horizontal direction as it descends, and the load due to the weight of the slide member 21 is converted into the horizontal direction. Since the pressing means A is adjacent to both ends of the fuel cell stack B, actually, the slide member 21 hardly moves down and moves in the horizontal direction, and the load in the horizontal direction and the fuel cell 10 It will be in the state where the force which spreads to the arrangement direction balances. Accordingly, the fact that the slide member 21 is moved in the horizontal direction as it descends means that the load due to its own weight is converted from the vertical direction to the horizontal direction in a state where it does not move but moves. Contains meanings.

Here, it is preferable to select an angle at which the load in the horizontal direction is maximized (around 45 degrees with respect to the horizontal direction) as the inclination angle of the first inclined surface 111 and the second inclined surface 211. Further, the material of the slide member 21 is used in a fuel cell storage container that becomes a high-temperature space, and therefore needs to be made of an oxidation-resistant material, and the fuel cell stack with a certain amount of load. Considering the point that it is necessary to further increase its own weight in order to press B, a relatively heavy material such as Fe—Cr refractory metal or ZrO ₂ is employed.

  Note that, when sliding between the first inclined surface 111 and the second inclined surface 211, it is necessary to suppress a decrease in load due to frictional force as much as possible. Therefore, the first inclined surface 111 and the second inclined surface 211 are used. It is preferable that either one of them is formed in a dimple shape over substantially the entire surface (a uniform recess is formed over the substantially entire surface) or a plurality of grooves are provided along the sliding direction. Further, in addition to the surface processing of the inclined surface, a ceramic powder may be dispersed between the first inclined surface 111 and the second inclined surface 211. A ceramic material such as boron nitride is preferably employed in consideration of the powdery material used at this time being used at a high temperature. The particle size of the ceramic powder is preferably 1 to 10 μm from the viewpoint of slipperiness.

The slide member 21 in the pressing means A shown in FIG. 1 is composed of one flat plate member, but a slide member 22 as shown in FIGS. 2A and 6 can also be adopted. This is divided into a plurality of sections by a cut surface 222 formed at an inclination angle substantially the same as that of the second inclined surface 221. The shown to form state in Fig. 1 (a), there is a possibility that the slide member 21 will be inclined to the rear side, the structure as shown in FIG. 2 (a), the fuel cell as shown in FIG. 2 (b) A pressing force can be applied evenly to the entire end face of the cell stack B. Since the other structure is the same as the pressing means A shown in FIGS. 1 and 5, the description thereof is omitted.

In the pressing means A shown in FIGS. 1 and 2, a load in the horizontal direction is generated by the weight of the slide members 21 and 22. At this time, depending on the size and material of the pressing means A, the slides 21 and 22 are generated. Is not so heavy, and a desired pressing force may not be applied to the fuel cell stack B. Therefore, in the present invention, by using the load application member 61 shown in FIG. 3, you to add further to its own weight.

  As shown in FIG. 3A, the load applying member 61 is shaped to simultaneously press the slide members 23 of the pair of pressing means A from above. Basically, it is composed of a rectangular frame portion 611 as viewed from above, but a portion (short side portion) in contact with the slide member 23 in the frame portion 611 is obliquely below on the fuel cell stack B side. The 3rd inclined surface 612 which faces is provided, and the frame body part 611 becomes relatively thick as it goes to the end (the lower end of the inclined surface). At this time, the length of the long side portion of the frame body portion 611 is slightly larger than the length of the fuel cell stack B in the fuel cell arrangement direction, and the length L1 of the short side portion of the frame body portion 611 is a slide. The width of the member 23 is substantially equal.

  The slide member 23 includes a fourth inclined surface 231 at the upper end facing obliquely upward on the opposite side of the fuel cell stack B so as to face the third inclined surface 612 of the load applying member 61. . The fourth inclined surface 231 has an inclination angle substantially equal to that of the third inclined surface 612. As shown in FIG. 3B, the first inclined surface 111 and the second inclined surface 232 are mutually connected. Along with the action, the interaction between the third inclined surface 612 and the fourth inclined surface 231 works to convert the load due to the weight of the slide member 23 in the horizontal direction.

  Here, the inclination angle of the first inclined surface 111 and the second inclined surface 232, the third inclined surface 612, and the fourth inclination so that the slide member 23 can apply a load in the horizontal direction without being inclined. It is preferable that the inclination angles in the surface 231 are substantially the same.

  Thus, by providing the load applying member 61 having the frame body portion 611 as a basic configuration, it is possible to increase the pressing force and to prevent the slide member 23 from tilting toward the back side. In addition, you may provide the cut surface 233 substantially parallel to the 2nd inclined surface 232 as shown in a figure.

  As still another embodiment, the pressing means shown in FIG. 4 that generates a stronger pressing force can be preferably employed.

  This is to eliminate the support portion 112 provided on the receiving member 11 shown in FIGS. 1 and 2, and to make the load applying member have the function of the support portion 112. FIG. As shown to (a), it is the load addition member 62 comprised from the frame part 621 and the drooping part 622. FIG. As described above, since the load applying member 62 functions as a support portion for supporting the slide member 24 from both sides and the back side, the frame body portion 621 shown in FIG. 4A is shown in FIG. It is formed slightly larger than the frame body portion 611. And the width L2 of the short side part in the frame part 621 shown to Fig.4 (a) is substantially equal to the sum of the thickness of the slide member 24 and the support part 112. FIG. In addition, the hanging part 622 is like the support part 112 of the receiving member 11 shown in FIG. 1 is removed and attached to the lower side of the short side part of the frame body part 621. The purpose of this shape is Since the weight of the load adding member 62 is added to the slide member 24 to increase the load (pressing force) in the horizontal direction, the slide member 24 can be lowered from the support portion 112 of the receiving member 11 shown in FIG. The amount of play is slightly shorter.

  Since the load application member 62 has the shape as described above, in this embodiment, the receiving member 12 has a shape without a support portion. In addition, an inclined surface is provided between the load application member 62 and the upper end of the slide member 24 so as to face each other. As shown in FIG. 4B, the first inclined surface 121 and the second inclined surface are provided. Along with the interaction of the surface 242, the interaction between the third inclined surface 623 and the fourth inclined surface 241 works to convert the load due to the weight of the slide member 24 into the horizontal direction. This is the same as the pressing means shown in FIG.

Next, an embodiment of a fuel cell and a fuel cell stack used in the fuel cell of the present invention will be described.
As shown in FIG. 9, the fuel cell 10 includes a flat support substrate 101 in which a plurality of fuel gas passages 101 a are formed at appropriate intervals, and various members are provided on the support substrate 101. Have a structure.

  The support substrate 101 has a flat cross section and arc-shaped portions at both ends of the flat portion. A fuel electrode layer 102 is provided so as to cover one of a pair of opposed surfaces of the flat portion and arcuate portions on both sides thereof. Further, a dense solid electrolyte layer 103 is formed so as to cover the fuel electrode layer 102. The air electrode 104 is laminated on the solid electrolyte layer 103 so as to correspond to the fuel electrode layer 102. An interconnector 105 is formed on the other surface of the flat portion where the fuel electrode layer 102 and the solid electrolyte layer 103 are not stacked. As is clear from FIG. 9, the fuel electrode layer 102 and the solid electrolyte layer 103 extend to both sides of the interconnector 105 and are configured so that the surface of the support substrate 101 is not exposed to the outside.

  In the fuel cell 10 having such a structure, the portion of the fuel electrode layer 102 facing the air electrode 104 operates as a fuel electrode to generate electric power. The current generated by such power generation is collected via the interconnector 105 attached to the support substrate 101.

Here, the support substrate 101 is required to be gas permeable in order to allow the fuel gas to permeate to the fuel electrode, and to be conductive in order to collect current via the interconnector 105. In addition to satisfying various requirements, in order to avoid the disadvantage of the difference in thermal expansion coefficient caused by simultaneous firing, an iron group metal component such as iron, nickel and cobalt and a rare earth oxide such as Y ₂ O ₃ and Yb ₂ O ₃ It consists of. Since the support substrate 101 is required to have fuel gas permeability, it is usually preferable that the open porosity is in the range of 30% or more, particularly 35 to 50%. Further, the conductivity of the support substrate 101 is preferably 300 S / cm or more, and particularly preferably 440 S / cm or more. The width of the flat portion of the support substrate 101 is normally 15 to 35 mm, the length of the arc-shaped portion (the length of the arc) is about 3 to 8 mm, and the thickness of the support substrate 101 is (on both sides of the flat portion). The distance is preferably about 2.5 to 5 mm.

The fuel electrode layer 102 is formed from porous conductive ceramics. For example, it is formed from ZrO ₂ in which a rare earth element is dissolved, and Ni and / or NiO. As ZrO ₂ (stabilized zirconia) in which the rare earth element is dissolved, the same one used for forming the solid electrolyte layer 103 described below is preferably used.

The solid electrolyte layer 103 provided on the fuel electrode layer 102 is generally formed of a dense ceramic called ZrO ₂ (usually stabilized zirconia) in which 3 to 15 mol% of a rare earth element is dissolved. . Examples of rare earth elements include Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, but they are inexpensive. From the point, Y and Yb are desirable.

The air electrode 104 is formed of a conductive ceramic made of a so-called ABO ₃ type perovskite oxide. As such a perovskite oxide, at least one of transition metal perovskite oxides, particularly LaMnO ₃ oxides, LaFeO ₃ oxides, and LaCoO ₃ oxides having La at the A site is preferable. LaFeO ₃ -based oxides are particularly suitable because they have high electrical conductivity at an operating temperature of about 1000 ° C. In the perovskite oxide, Sr and the like may exist together with La at the A site, and Co and Mn may exist together with Fe at the B site.

The interconnector 105 provided on the support substrate 101 is generally made of a lanthanum chromite perovskite oxide (LaCrO ₃ oxide). Further, in order to prevent leakage of the fuel gas passing through the inside of the support substrate 101 and the oxygen-containing gas passing through the outside of the support substrate 101, such conductive ceramics must be dense, for example, 93% or more, particularly 95%. It is preferable to have the above relative density. Although not shown, it is preferable to provide a P-type semiconductor layer made of, for example, a transition metal perovskite oxide on the outer surface (upper surface) of the interconnector 105.

As shown in FIGS. 5 to 8, the fuel battery cell stack B includes, for example, a plate-shaped current collecting member 20 formed by spreading a plurality of current collecting pieces and giving elasticity to the fuel battery cell 10 and the fuel battery. It is obtained by interposing between the cells 10 and electrically connecting a plurality of fuel cells 10 in series and arranging them on a manifold. At this time, the lower ends of the plurality of fuel cells 10 are inserted into through holes (not shown) formed in the upper lid of the manifold, and are joined by glass or the like. An end current collecting member 201 is disposed at both ends, and the end current collecting member 201 is pressed by the pressing means A. When fuel gas is supplied into the manifold, it passes through the fuel gas passage 101a of the fuel cell 10 and flows upward. 5 is a reference example in which the pressing means A shown in FIG. 1 is arranged at both ends of the fuel cell stack B, and FIG. 6 is a reference example in which the pressing means shown in FIG. 2 is arranged at both ends of the fuel cell stack. There, FIG. 7 is pressing means, 8 shown in Figure 3 is arranged at both ends of the fuel cell stack pressing means shown in FIG.

The fuel cell can be obtained by multiple housing Rutotomoni pressing means A are arranged in both ends, the further comprising a fuel cell stack B frame-shaped load application member accommodating container. By such a fuel cell stack and a fuel cell, a fuel cell excellent in long-term reliability with little voltage drop can be obtained.

In the fuel cell of the present invention, it is only necessary to press both ends of the fuel cell stack by converting the load due to the weight of the member included in the pressing means in the horizontal direction, and the shape is limited to the shape of this example. It is not something .

Here, a manufacturing method of the fuel cell and the fuel cell stack will be described.
First, a slurry is prepared by mixing an iron group metal such as Ni or its oxide powder, a rare earth oxide powder such as Y ₂ O ₃ , an organic binder, and a solvent, and extrusion using this slurry. A support substrate molded body is produced by molding and dried.

  Next, a fuel electrode layer forming material (Ni or NiO powder and stabilized zirconia powder), an organic binder, and a solvent are mixed to prepare a slurry, and a sheet for the fuel electrode layer is prepared using this slurry. Further, instead of producing a sheet for the fuel electrode layer, a paste in which the fuel electrode forming material is dispersed in a solvent is applied to a predetermined position of the formed support substrate and dried, and then the fuel electrode layer is formed. A coating layer may be formed.

Furthermore, a stabilized zirconia powder, an organic binder, and a solvent are mixed to prepare a slurry, and a solid electrolyte layer sheet is prepared using this slurry.

  The support substrate molded body, the fuel electrode sheet and the solid electrolyte layer sheet formed as described above are laminated so as to have a layer structure as shown in FIG. 9, for example, and dried. In this case, when the coating layer for the fuel electrode layer is formed on the surface of the support substrate molded body, only the solid electrolyte layer sheet may be laminated on the support substrate molded body and dried.

Thereafter, the interconnector material (e.g., LaCrO ₃ based oxide powder), an organic binder and a solvent were mixed to prepare a slurry, to produce the interconnector sheet.

  This interconnector sheet is further laminated at a predetermined position of the laminate obtained above to produce a firing laminate.

  Next, the above laminate for firing is subjected to binder removal treatment, and co-fired at 1300 to 1600 ° C. in an oxygen-containing atmosphere to obtain a sintered body.

Next, a paste containing an air electrode forming material (for example, LaFeO ₃ -based oxide powder) and a solvent and, if necessary, a P-type semiconductor layer forming material (for example, LaFeO ₃ -based) at a predetermined position of the sintered body. Oxide powder) and a solvent-containing paste were applied by dipping or the like, and an air electrode coating layer was provided on the surface of the solid electrolyte layer. At the same time, the paste is applied to the outer surface of the interconnector formed in the sintered body, a P-type semiconductor coating layer is provided, and baking is performed at 1000 to 1300 ° C.
A fuel cell is produced through the above steps.

  Then, a current collecting member processed into a desired shape is prepared using a Fe-Cr heat-resistant alloy plate having a thickness of 0.3 to 0.6 mm, and the current collecting member and the above-described fuel cell are electrically connected. In addition, a paste prepared by mixing a powder composed of the transition metal perovskite oxide, which is the P-type semiconductor, an organic binder, and a solvent for mechanical bonding, is used as the air electrode and the interconnector surface of the fuel cell. And after apply | coating to a current collection member, a fuel cell and a current collection member are laminated | stacked alternately, and it bakes at 1000-1300 degreeC. Further, the stacked fuel cell and the current collecting member are disposed in a manifold, and the fuel cell and the manifold are sealed with glass or the like, thereby producing a fuel cell stack.

  The fuel cell is manufactured by arranging the plurality of cell stacks in a storage container and piping a fuel gas introduction tube and an air introduction tube for sending the fuel cell to the fuel cell for use in power generation.

It is explanatory drawing which extracts and shows one Embodiment of the press means in the fuel cell of this invention, (a) is a perspective view, (b) is explanatory drawing of the load direction by the slide member 21 shown to (a). It is explanatory drawing which extracts and shows other embodiment of the slide member 21 shown in FIG. 1, (a) is a perspective view, (b) is explanatory drawing of the load direction by the slide member 22 shown to (a). It is an explanatory view showing an example of the implementation form that put the fuel cell of the present invention, (a) is a perspective view, (b) is illustration of the load direction by the slide member 23 shown in (a). It is an explanatory view showing another embodiment that put the fuel cell of the present invention, (a) is a perspective view, (b) is illustration of the load direction by the slide member 23 shown in (a). FIG. 2 is a reference diagram of a fuel cell including the pressing unit shown in FIG. 1. FIG. 3 is a reference diagram of a fuel cell provided with pressing means shown in FIG. 2. It is explanatory drawing of the fuel cell provided with the press means shown in FIG. It is explanatory drawing of the fuel cell provided with the press means shown in FIG. It is explanatory drawing which shows one Embodiment of the fuel cell in the fuel cell of this invention.

Explanation of symbols

A ... Pressing means B ... Fuel cell stack 10 ... Fuel cell 20 ... Current collecting member 201 ... End current collecting member 30 ... Manifold 11, 12 ... Receiving members 21, 22, 23, 24 ..Slide members 111, 121... First inclined surfaces 211, 2221, 232, 242 ..second inclined surfaces 112 ..support portions 222, 233 ..cut surfaces 61, 62. 621 ··· Frame portions 612 and 623 · · Third inclined surfaces 231 and 241 · · Fourth inclined surfaces 622 · · Hanging portions

Claims (3)

A fuel cell stack in which fuel cell cells and current collecting members for electrically connecting adjacent fuel cell cells are alternately arranged in series in one direction and are erected on a manifold A fuel cell housed inside,
A receiving member having a first inclined surface facing obliquely upward on the fuel cell stack side; and an obliquely lower side opposite to the fuel cell stack so as to face the first inclined surface of the receiving member. A flat plate-like slide member having a second inclined surface facing the lower end, and the slide member is lowered as the second inclined surface slides with respect to the first inclined surface. A pressing means that also moves in the horizontal direction is provided adjacent to both sides of the fuel cell stack,
The slide member has a fourth inclined surface at the upper end facing obliquely upward on the opposite side to the fuel cell stack, and
A third slope that is disposed above the fuel cell stack and that faces obliquely downward on the fuel cell stack side that is in contact with a fourth slope of each slide member disposed on both sides of the fuel cell stack. A fuel cell, further comprising a frame-shaped load applying member having a surface.   Either one of the first inclined surface and the second inclined surface is formed in a dimple shape over substantially the entire surface, or a plurality of grooves are formed along the sliding direction. The fuel cell according to claim 1.   The fuel cell according to claim 1 or 2, wherein a ceramic powder is dispersed between the first inclined surface and the second inclined surface.

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