JP2007004994A - Solid polymer fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid polymer fuel cell without the use of a separator. <P>SOLUTION: In the solid polymer fuel cell (10) which is formed by serially connecting a plurality of fuel cell units (20) with the use of an organic gel electrolyte film (24), the fuel cell unit is provided with: an oxygen electrode (28) having an oxygen electrode (30) made of a carbon fiber non-woven fabric; and hydrogen electrodes (36, 42) having hydrogen electrodes (38, 44) made of a carbon fiber non-woven fabric. The unit is also configured to supply the organic gel electrolyte film with an oxygen gas introduced from a periphery of the oxygen electrode and a hydrogen gas introduced from a periphery of the hydrogen electrode, respectively. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention generally relates to small and light polymer electrolyte fuel cells. More specifically, the present invention relates to a polymer electrolyte fuel cell that does not use a separator.

  In general, a so-called stack structure in which a large number of cells are stacked using a separator is employed for a fuel cell. Since the output voltage of one unit is 0.6V to 0.8V, a fuel cell is formed by connecting a large number of units in series to obtain a high output voltage. Is done. The separator provided with gas flow paths on the front and back sides is a hydrogen gas / oxygen gas separator, and also serves to form a voltage transmission medium, a current collector, and a fuel cell skeleton.

  On the other hand, fuel cells that do not use a separator have also been developed. For example, the fuel cell described in Patent Document 1 is configured to use a carbon nonwoven fabric as an electrode and a gas flow path.

Japanese Patent Laid-Open No. 9-289027

  However, the separator has a problem that it is expensive because it needs to engrave a gas channel with a special device into a carbon material or a special alloy material. Further, as described above, the fuel cell has a problem that the weight of the fuel cell itself increases because a large number of units must be coupled in series and a separator must be inserted between the units. Furthermore, since hydrogen gas is likely to leak, the stack structure using a separator also has a problem that a structure that strongly tightens the separator must be employed. On the other hand, in the fuel cell described in Patent Document 1 described above, although the above-mentioned problems relating to price and weight appear to be solved, the shrinkage of the carbon nonwoven fabric itself, instability of the shape, lack of compressive strength, Because there are problems such as lack of complete sealing, it seems to be accompanied by various difficulties in practical use.

  Accordingly, an object of the present invention is to provide a solid polymer fuel cell that can be put into practical use without using a separator.

  In the present invention, an organic gel electrolyte that is an organic polymer is used as a method for operating a fuel cell at room temperature. From the viewpoint of fuel cell production, organic gel electrolytes have the advantage of being inexpensive and easy to produce membranes, but are mechanically weak and easy to break, and they swell by taking up a large amount of water. Therefore, it is not easy to manufacture a fuel cell having a stack structure using a separator.

  Therefore, the present inventor conducted research on the manufacture of a fuel cell that does not use a separator. That is, research was advanced to replace the function and role of the separator with other parts. In the fuel cell without a separator of the present invention, gas is supplied to the electrolyte membrane by turbulent flow passing through the gaps in the carbon fiber nonwoven fabric. At this time, since the gas flows through an irregular gap of several tens of μm, it receives turbulent resistance. Therefore, it is difficult to uniformly supply the gas from the gas supply pipe to the electrolyte membrane. Therefore, the present inventor provides a gap of 0.5 mm to 1.0 mm between the carbon fiber nonwoven fabric serving as an electrode and the surrounding frame material (gasket), and hydrogen gas or oxygen gas supplied from the gas pipe is provided. At the same time as entering the carbon fiber nonwoven fabric, the carbon fiber nonwoven fabric was allowed to flow freely into the predetermined gap and then into the carbon fiber nonwoven fabric.

  The polymer electrolyte fuel cell according to claim 1 is formed by connecting a plurality of fuel cell units using an organic gel electrolyte membrane in series, and the fuel cell unit is formed of a carbon fiber nonwoven fabric. An oxygen electrode portion having an oxygen electrode and a hydrogen electrode portion having a hydrogen electrode formed of a carbon fiber nonwoven fabric, introducing oxygen gas from the outer periphery of the oxygen electrode, and introducing hydrogen gas from the outer periphery of the hydrogen electrode The organic gel electrolyte membrane is supplied to each of the organic gel electrolyte membranes.

  The polymer electrolyte fuel cell according to claim 2 of the present application is the fuel cell according to claim 1, wherein the oxygen electrode portion includes a frame member disposed around the oxygen electrode, and the oxygen electrode and the A gap communicating with an oxygen gas flow hole provided in the frame material is provided between the frame material, oxygen gas is introduced from the oxygen gas flow hole into the oxygen electrode through the gap, and The organic gel electrolyte membrane in contact with the oxygen electrode is configured to be supplied.

  The solid polymer fuel cell according to claim 3 of the present application is the fuel cell according to claim 1 or 2, wherein the hydrogen electrode portion includes a first hydrogen electrode portion and a second hydrogen electrode portion. The electrode part has a frame member arranged around the first hydrogen electrode, the second hydrogen electrode part has a frame member arranged around the second hydrogen electrode, and the first hydrogen electrode part And the second hydrogen electrode part are formed so that the first hydrogen electrode and the second hydrogen electrode at least partially overlap each other, and between the second hydrogen electrode and the frame member A gap communicating with the hydrogen gas flow hole provided in the frame member is provided, and hydrogen gas is introduced from the hydrogen gas flow hole into the second hydrogen electrode through the gap, and the second hydrogen electrode Said first hydrogen electrode being at least partially in contact with, then And it is characterized in that it is configured to be supplied to the organic gel electrolyte film in contact with the serial first hydrogen electrode.

  The solid polymer fuel cell according to claim 4 of the present application is the fuel cell according to any one of claims 1 to 3, wherein the fuel cell unit is larger than the vertical and horizontal dimensions between the fuel cell units. A stainless steel plate having vertical and horizontal dimensions is disposed, a plurality of the fuel cell units are connected in series, and the fuel cell units are firmly fixed to each other by a fastener. .

  Since the fuel cell of the present invention does not require a separator, a lightweight and inexpensive fuel cell can be provided. Moreover, in the fuel cell of this invention, since it is comprised so that fuel gas may be supplied from the outer periphery of an electrode, fuel gas can be efficiently flowed in in the carbon fiber nonwoven fabric which forms an electrode. Further, in the fuel cell of the present invention, since the frame serves as a gasket, it is possible to efficiently prevent hydrogen gas from leaking. In the fuel cell of the present invention, since the frame material is disposed around the electrolyte membrane and the electrode, the shape of the fuel cell unit itself can be stabilized and strength can be imparted. Furthermore, in the fuel cell of the present invention, by arranging the stainless steel plates having large vertical and horizontal dimensions between the fuel cell units, the stainless steel plate not only serves as a current collector and shape retention material for the fuel cell, but also air cooling means. Also works.

  Next, a polymer electrolyte fuel cell according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. A polymer electrolyte fuel cell 10 according to a preferred embodiment of the present invention is formed by connecting a plurality of fuel cell units in series. FIG. 1 is an exploded perspective view of the fuel cell unit 20.

  The fuel cell unit 20 includes an electrolyte part 22, an oxygen electrode part 24 disposed on one side of the electrolyte part 22, and a first hydrogen electrode part 36 and a second hydrogen electrode disposed on the other side of the electrolyte part 22. Part 44.

  As shown in FIG. 2A, the electrolyte portion 22 includes a rectangular organic gel electrolyte membrane 24 and a frame member 26 disposed around the organic gel electrolyte membrane 24. As shown in FIG. 2 (b), there is substantially no gap between the outer periphery of the organic gel electrolyte membrane 24 and the inner periphery of the frame member 26 (in other words, the organic gel electrolyte membrane 24 of the organic gel electrolyte membrane 24). The outer periphery and the inner periphery of the frame member 26 are in contact). The frame member 26 is provided with an oxygen gas flow hole 26a, a hydrogen gas flow hole 26b, and a fastener insertion hole 26c.

  As shown in FIG. 3A, the oxygen electrode portion 28 includes an oxygen electrode 30 formed of a substantially rectangular carbon fiber nonwoven fabric and a frame member 32 disposed around the oxygen electrode 30. . As best shown in FIG. 3B, a gap 34 is provided between the oxygen electrode 30 and the frame member 32, and the gap 34 communicates with an oxygen gas circulation hole 32a described later. The width of the gap 34 is preferably about 0.5 mm to about 1.0 mm. The frame member 32 has an outer shape substantially the same size as the frame member 26. Further, the frame member 32 has oxygen gas flow holes 32a and hydrogen gas at substantially the same positions as the positions where the oxygen gas flow holes 26a, hydrogen gas flow holes 26b, and fastener insertion holes 26c of the frame material 26 are provided. A circulation hole 32b and a fastener insertion hole 32c are provided.

  As shown in FIG. 4A, the first hydrogen electrode portion 36 includes a first hydrogen electrode 38 formed of a substantially rectangular carbon fiber nonwoven fabric, and a frame member 40 disposed around the first hydrogen electrode 38. And have. As shown in FIG. 4B, there is substantially no gap between the outer periphery of the first hydrogen electrode 38 and the inner periphery of the frame member 40 (in other words, the first hydrogen electrode 38 has The outer periphery and the inner periphery of the frame member 40 are in contact). The frame member 40 has an outer shape that is substantially the same size as the frame member 26. In addition, the frame material 40 has oxygen gas flow holes 40a and hydrogen gas at substantially the same positions as the positions where the oxygen gas flow holes 26a, hydrogen gas flow holes 26b, and fastener insertion holes 26c of the frame material 26 are provided. A circulation hole 40b and a fastener insertion hole 40c are provided.

  As shown in FIG. 5A, the second hydrogen electrode portion 42 includes a pair of second hydrogen electrodes 44 formed of a carbon fiber nonwoven fabric, and a frame member 46 disposed around each second hydrogen electrode 44. And have. A gap 48 is provided between the second hydrogen electrode 44 and the frame member 46, as best shown in FIGS. 5B and 5C. The gap 48 is a hydrogen gas described later. It leads to the circulation hole 46b. The width of the gap 48 is preferably about 0.5 mm to about 1.0 mm. The size and position of the first hydrogen electrode 38 and the second hydrogen electrode 44 are selected so that they overlap at least partially when the first hydrogen electrode portion 36 and the second hydrogen electrode portion 42 are overlapped. . The frame member 46 has an outer shape that is substantially the same size as the frame member 26. In addition, the frame material 46 has oxygen gas flow holes 46a and hydrogen gas at substantially the same positions as the positions where the oxygen gas flow holes 26a, hydrogen gas flow holes 26b, and fastener insertion holes 26c of the frame material 26 are provided. A circulation hole 46b and a fastener insertion hole 46c are provided.

  The frame members 26, 32, 40, and 46 are formed of an appropriate synthetic resin material such as plastic having a smooth surface. Since the frame members 26, 32, 40, 46 are configured as described above, when the electrolyte part 22, the oxygen electrode part 28, the first hydrogen electrode part 36, and the second hydrogen electrode part 42 are overlapped, the outer shape is Since the oxygen gas flow holes and the hydrogen gas flow holes are located at the same location, the oxygen gas flow passage (two in the illustrated example) and the hydrogen gas flow passage (illustrated) are substantially the same. In the example, 4) will be formed.

  The carbon fiber nonwoven fabric that forms the oxygen electrode 30 and the first and second hydrogen electrodes 38 and 44 preferably uses water-repellent treatment on the surface in order to discharge water generated during power generation. .

  FIG. 7 is a diagram showing a fuel cell 10 formed by connecting a plurality of fuel cell units 20 configured as described above (eight in the illustrated example) in series. A stainless steel plate 50 is disposed between the fuel cell units 20. As shown in FIG. 6, the stainless steel plate 50 is formed so that the vertical and horizontal dimensions (for example, about 5 mm) are larger than the frame members 26, 32, 40, 46. When stacked, the oxygen gas flow hole 50a, the hydrogen gas flow hole 50b, and the fastener insertion hole 50c are respectively provided at the same positions as the positions where the oxygen gas flow hole, the hydrogen gas flow hole, and the fastener insertion hole are provided. Is provided. The stainless steel plate 50 serves as a current collector, a heat radiator, and a shape retaining material. In addition, since the stainless steel plate 50 is not in direct contact with the organic gel electrolyte membrane 24, there is no fear of corrosion.

  In FIG. 7, reference numerals 52 and 54 denote an outer plate and a fastener (screw / nut), respectively. The fastener 54 is preferably formed of an insulator (for example, glass fiber / polyamide). Further, oxygen gas supply pipes are connected to the oxygen gas flow holes 26a, 32a, 40a, 46a, 50a, and hydrogen gas supply pipes are connected to the hydrogen gas flow holes 26b, 32b, 40b, 46b, 50b. In addition, oxygen gas and hydrogen gas are respectively supplied from an oxygen gas supply source and a hydrogen gas supply source (both not shown).

  The operation of the fuel cell 10 configured as described above will be described. Oxygen gas and hydrogen gas are respectively supplied to the oxygen gas supply pipe and the hydrogen gas supply pipe. The oxygen gas that has flowed into the oxygen gas flow hole through the oxygen gas supply pipe flows into the oxygen electrode 30 from the oxygen gas flow hole 32a of the oxygen electrode portion 28, and at the same time, through the gap 34 that communicates with the oxygen gas flow hole 32a. The oxygen electrode 30 flows into the oxygen electrode 30 from the outer periphery. On the other hand, the hydrogen gas that has flowed into the hydrogen gas flow hole through the hydrogen gas supply pipe flows into the second hydrogen electrode 44 from the hydrogen gas flow hole 46b of the second hydrogen electrode portion 42, and at the same time communicates with the hydrogen gas flow hole 46a. It flows into the second hydrogen electrode 44 from the outer periphery of the second hydrogen electrode 44 through the gap 48, and then flows into the first hydrogen electrode 38 that at least partially overlaps the second hydrogen electrode 44. In this way, the fuel gas (oxygen gas, hydrogen gas) is uniformly supplied to the oxygen electrode 30 / first hydrogen electrode 38 in contact with the organic gel electrolyte membrane 24, so that power generation is performed efficiently. .

  The reason for using two hydrogen electrodes (the first hydrogen electrode 38 and the second hydrogen electrode 44) is to increase the component of hydrogen gas flowing toward the surface of the organic gel electrolyte membrane 24. On the other hand, the reason for using one oxygen electrode (oxygen electrode 30) is that it is not necessary to provide two oxygen electrodes because a large amount of air is supplied to the oxygen electrodes and the gas flow rate is high. The oxygen electrode 30 and the first hydrogen electrode 38 are preferably larger than the organic gel electrolyte membrane 24. Further, since the frame members 26, 32, 40, 46 are formed of a material having a smooth surface, leakage of fuel gas (oxygen gas / hydrogen gas) can be effectively prevented. Furthermore, since the stainless steel plate 50 is formed to have a size larger than that of the frame member, it becomes an effective air cooling means.

  FIG. 8 is a graph obtained by examining the power generation characteristics of the fuel cell unit having the above-described configuration in order to verify the effectiveness of the fuel cell of the present invention. This fuel cell unit has an outer diameter of 80 mm × 80 mm and a gel electrolyte membrane size of 40 mm × 40 mm, operates at room temperature, and starts power generation within a few seconds after the fuel gas is supplied. The organic gel electrolyte has an advantage that it is inexpensive and easy to produce a film, but has a disadvantage that it is mechanically weak and easily broken and has a strong swelling property. Therefore, the present inventor used a reinforced gel electrolyte membrane having a breaking strength of 5 times or more and an improved swelling degree of about 1/3. As shown in FIG. 8, it was verified that the fuel cell unit of the present invention has an ability comparable to that of a fuel cell (80 ° C. operation) using a Nafion electrolyte membrane that has been reported in the past. .

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say, it is something.

  For example, the shapes of the organic gel electrolyte membrane 24, the oxygen electrode 30, the first hydrogen electrode 38, and the second hydrogen electrode 44 in the above embodiment are exemplary, and other arbitrary shapes may be selected. . Also, oxygen gas flow holes 26a, 32a, 40a, 46a, 50a provided in each frame member, hydrogen gas flow holes 26b, 32b, 40b, 46b, 50b, fastener insertion holes 26c, 32c, 40c, 46c, The number and position of 50c are also exemplary and are not limited to those illustrated.

It is a disassembled perspective view of a fuel cell unit. 2A is a front view showing an electrolyte part of the fuel cell unit of FIG. 1, and FIG. 2B is a cross-sectional view taken along line 2b-2b of FIG. 2A. 3A is a front view showing the oxygen electrode portion of the fuel cell unit of FIG. 1, FIG. 3B is a cross-sectional view taken along line 3b-3b of FIG. 3A, and FIG. ) Is a cross-sectional view taken along line 3c-3c in FIG. 4A is a front view showing the first hydrogen electrode portion of the fuel cell unit of FIG. 1, and FIG. 4B is a cross-sectional view taken along line 4b-4b of FIG. 4A. 5A is a front view showing a second hydrogen electrode portion of the fuel cell unit of FIG. 1, and FIG. 5B is a cross-sectional view taken along line 5b-5b of FIG. 5A. It is a perspective view of a stainless steel plate. It is the figure which showed the fuel cell formed by joining a plurality of fuel cell units in series. It is the figure which showed the electric power generation characteristic of the fuel cell unit of FIG. 1, ie, the current-voltage curve.

DESCRIPTION OF SYMBOLS 10 Polymer electrolyte fuel cell 20 Fuel cell unit 22 Electrolyte part 24 Organic gel electrolyte membrane 26 Frame material 28 Oxygen electrode part 30 Oxygen electrode 32 Frame material 34 Crevice 36 1st hydrogen electrode part 38 1st hydrogen electrode 40 Frame material 42 1st 2 Hydrogen electrode part 44 2nd hydrogen electrode 46 Frame material 48 Gap 50 Stainless steel plate 52 Outer plate 54 Fastener 26a, 32a, 40a, 46a, 50a Oxygen gas flow hole 26b, 32b, 40b, 46b, 50b Hydrogen gas flow hole 26c 32c, 40c, 46c, 50c Fastener insertion hole

Claims (4)

A polymer electrolyte fuel cell formed by connecting a plurality of fuel cell units using an organic gel electrolyte membrane in series,
The fuel cell unit is
An oxygen electrode portion having an oxygen electrode formed of a carbon fiber nonwoven fabric;
A hydrogen electrode part having a hydrogen electrode formed of a carbon fiber nonwoven fabric,
A fuel cell, wherein oxygen gas is introduced from the outer periphery of the oxygen electrode, hydrogen gas is introduced from the outer periphery of the hydrogen electrode, and supplied to the organic gel electrolyte membrane. The oxygen electrode portion has a frame member disposed around the oxygen electrode, and a gap is formed between the oxygen electrode and the frame member so as to communicate with an oxygen gas circulation hole provided in the frame member. Oxygen gas is introduced into the oxygen electrode from the oxygen gas flow hole through the gap and is supplied to the organic gel electrolyte membrane in contact with the oxygen electrode. The fuel cell according to claim 1, wherein The hydrogen electrode part is composed of a first hydrogen electrode part and a second hydrogen electrode part, and the first hydrogen electrode part has a frame member arranged around the first hydrogen electrode,
The second hydrogen electrode portion has a frame member disposed around the second hydrogen electrode;
When the first hydrogen electrode portion and the second hydrogen electrode portion are overlapped, the first hydrogen electrode and the second hydrogen electrode are formed to overlap at least partially,
A gap is provided between the second hydrogen electrode and the frame member so as to communicate with a hydrogen gas flow hole provided in the frame member, and hydrogen gas passes through the gap from the hydrogen gas flow hole. Introduced into the second hydrogen electrode and supplied to the first hydrogen electrode at least partially in contact with the second hydrogen electrode and then to the organogel electrolyte membrane in contact with the first hydrogen electrode The fuel cell according to claim 1, wherein the fuel cell is configured. A stainless steel plate having a vertical and horizontal dimension larger than the vertical and horizontal dimensions of the fuel cell unit is arranged between the fuel cell units, a plurality of the fuel cell units are connected in series, and the fuel cell units are firmly fixed to each other by a fastener. The fuel cell according to claim 1, wherein the fuel cell is formed by being fixed to the fuel cell.

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