JPS60189868A - Reaction fluid feed structure to fuel cell electrode layer - Google Patents

Abstract

PURPOSE:To obtain a uniform current distribution on the electrode layer surface by decreasing the diffusion resistance value from the inlet toward the outlet of fluid paths at diffusion paths where a reaction fluid is diffused i a porous electrode substrate and reaches an electrode layer. CONSTITUTION:An electrode substrate having grooves feeding fuel gas and an electrode substrate having grooves feeding oxidizer gas are closely stuck to both sides of a unit cell consisting of an electrolyte, a fuel electrode, and an oxidizer electrode, and they are laminated to form a fuel cell stack. In this case, the gas feed grooves 4a of each electrode substrate 4 are formed so that the number of branch feed grooves is increased from the inlet section toward the outlet section and the lengths of diffusion paths from the feed grooves 4a to the electrode 2 through the electrode substrate 4 are shortened. Accordingly, the density decrease of the reaction component in a reaction fluid is compensated, a uniform current distribution is obtained on the electrode layer surface, and the cell life can be extended by decreasing the diffusion resistance value toward the outlet section.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a porous electrode in contact with a nipolar layer that performs power generation in a fuel cell to which a reactive fluid containing non-reactive components is supplied. A base material is provided, and a reaction fluid is passed through a plurality of reaction fluid passages provided on the side opposite to the electrode layer, and diffuses within the electrode base material to form an electrode. The present invention relates to a structure for supplying a reactive fluid to a fuel cell electrode layer that supplies a reactive fluid to the layer.

a porous membrane with passages for the reactant fluid to the and oxidizer electrodes;
A polar crystal phase is arranged, and the reaction fluid is diffused from the passageway into the electrode A'h and supplied to the 1F/5 electrodes to perform an electrochemical reaction. Gas is used as a fluid, reforming residue mainly composed of hydrogen is used as a fuel gas as a reaction gas, air is supplied to a unit cell as an oxidizer residue, and an electrochemical reaction is carried out. Hydrogen and oxygen in the reactive gas are consumed as the reactive gas flows from the inlet to the outlet of the passage, and the levels of these components gradually decrease. The prior art will be explained below based on the drawings.

FIG. 1 is an exploded perspective view showing the structure of a conventional fuel cell, in which an electrolyte 1 is sandwiched, a fuel electrode 2 and an oxidizer electrode 3 are arranged on both sides τ10, and a fuel L12 pole 2 is placed on the outside. An electrode 4 having grooves 4a formed as passages for supplying fuel gas on the opposite side of the surface that contacts the oxidizer electrode 3 is in close contact with the fuel 1 electrode 2, and also supplies the fuel gas on the surface opposite to the surface that contacts the oxidizer electrode 3. An electrode base material 5 in which a groove 5a for supplying oxidant gas, which is provided in a direction perpendicular to the groove 4a, is formed as a passage.
is closely attached to the unit battery of the CIJ type as much as possible,
Gas non-diffusive separate plate 6 is provided between each unit battery.
These cells are interposed in multiple layers to form each cell stack.

A manifold 7 having an inlet pipe 7a for supplying fuel gas is provided on one side of the cell stack, and a manifold 7 having an outlet pipe for discharging fuel gas (not shown) is provided on the opposite side. , and a manifold 8 having an inlet pipe 8a for supplying oxidant gas, or a manifold 8 provided on the side of the cell stack perpendicular to the surface for supplying and discharging fuel gas, and having an outlet pipe for discharging oxidant gas (not shown). A fuel cell is configured by being provided on the side surface of the cell stack facing the above.

In operation of the fuel cell, fuel gas as a reaction gas is passed through the inlet pipe 7.
The fuel gas flows into the fuel gas supply groove 4a of the cell stack through the manifold 7, diffuses into the porous electrode base material 4, and is supplied to the fuel electrode 2. The fuel gas is collected in an exhaust manifold (not shown). Then, the exit part will be ejected. On the other hand, the oxidant gas is also made into J8 (4), passed through the supply manifold 8 to the supply groove 5a for the C oxidant residue, and diffused into the porous electrode halo 5 to supply the oxidant to the electrode 3.
The oxidant gas Fi is collected in a discharge manifold (not shown) and discharged through an outlet pipe, and these reaction gases are fed into the unit cell 'ii! , 'Gas chemical reaction All chemical reactions occur.0 Figure 2 is a diagram showing the situation in which the above-mentioned reaction gas diffuses inside the porous electrode base side, and the fuel gas is supplied from the electrode profiteer 4. k 4 a flows in the direction of arrow A, diffuses in the electrode crystal phase 4 in the direction of arrow B, and is supplied to fuel t4 (Wataru 2), and the oxidant gas flows through the supply groove 5a of the electrode profiteer 5 as shown in the paper. It flows in the right angle direction and diffuses in the electrode base material 5 in the direction of arrow C, and the oxidizing agent is supplied to the electrode 3, and the electrolyte in the matrix 1 and oxygen and hydrogen in the reaction gas undergo an electrochemical reaction at the electrode. .

Therefore, oxygen in the air and hydrogen in the reformed gas are loaded from the inlet to the outlet of the supply groove, which serves as a passage for the reaction scum.
i gradually decreases〇Therefore, as shown in FIG. In the conventional type using polar blades, the reaction gas is two-dimensionally diffused within the electrode base material from the reaction gas supply groove.The average diffusion resistance is constant throughout the passage, so the reaction gas supplied to each electrode is The amount of oxygen and hydrogen therein is directly influenced by the concentration of oxygen and hydrogen components in the reaction gas flowing through the feed channel.

Therefore, on the electrode surface, a non-uniform current distribution occurs, in which the generated current is large at the inlet of the reaction scum, and conversely, the generated current is small at the outlet. How does the change over time in the T-pond characteristics depend on the IL current density? b. The higher the flow density, the higher the temperature due to the increase in heat generation density, and the greater the deterioration of the resiliency over time. Therefore, when a fuel cell with an uneven current distribution is operated for a long period of time, the parts with high current density will deteriorate first, and the current density in adjacent parts will increase to compensate for the current in the deteriorated parts. , the areas of deterioration gradually expand.

is constant along the path consisting of the reactant gas supply groove, the amount of reactant gas supplied to the '7Li,' electrode is affected by the g2 degree of the reactant gas component, and an uneven current distribution is unavoidable. It has the disadvantage of frost, which has a negative effect on the lifespan of the pond.

[Purpose of the invention]

In view of the above-mentioned drawbacks, the present invention provides an IL-
It is an object of the present invention to provide a fuel cell 1 [1, a structure for supplying a reactive fluid to an electrode layer, in which the amount of components of the reactive fluid supplied to the electrode is almost uniform on the surface of the electrode layer by diffusing the polar base.

[Chivalry of invention]

In order to achieve the above object, according to the present invention, a reaction fluid containing non-reactive components is supplied with an electrolyte in a fuel cell. - a porous electrode base I is disposed adjacent to the electrode, and a plurality of threads of reaction fluid channels arranged on the side of the electrode base opposite to the electrode layer, e.g. The reaction fluid flows through the provided grooves or into the grooves provided parallel to the gas-nondiffusive plate facing the electrode base material and diffuses within the electrode group 1, supplying the electrode layer reaction fluid. However, the average diffusion resistance of the two-dimensional diffusion path where the reaction fluid diffuses from the surface η11 of the electrode base material facing the reaction fluid stop J path to the inside of the electrode base and reaches the electrode layer. , i.e. 'ij
1゜ The average diffusion resistance value determined by the length of the diffusion path within the polar base village, the porosity of the electrode base material, the temperature of the reaction component in the reaction fluid flowing through the reaction fluid passage, and the temperature from the inlet to the exit of this passage. 1 is achieved by making it proportional across the parts.

[The fruitful side of invention]

The present invention will now be described in detail based on the drawings.

FIG. 4 is a perspective view of a ribbed electrode base material according to an embodiment of the present invention; FIG.

Figure 6 is a sectional view taken along line X-X and Y-Y in Figure 4, respectively.
FIG. In addition, a) In the figures after Figure 4, the same parts as in Figures 1, 2, and 3 have the same ladle.

In FIG. 4, the fuel gas of the reaction scum as a reaction fluid flows in the direction of the arrow in the supply groove 4a as the reaction fluid 3i11 path of the porous ill and the pole base piece 4, but the number of the supply grooves 4a is the same as that of the arrow. The number of branch supply grooves increases in the direction, that is, in the direction in which the fuel gas flows from the inlet to the outlet.

Therefore, as the number of branch supply grooves increases, the distance between the supply grooves that are in contact with each other by 1 μF becomes shorter, and the length of the diffusion path that diffuses from the silk rjf to the electrode group also becomes shorter.

FIG. 5 shows a porous electrode base material 4 in which the fuel gas is supplied from the supply groove 4a.
X diffused inside and supplied to fuel 'KL 4'm '2
The state at -X section m1 is shown, and the fuel is supplied to the fuel 11 box electrode 2 after being two-dimensionally diffused in the direction of the arrow from the inner surface and bottom surface of the supply groove 4a.

Figure 6 is close to the fuel gas outlet side, so X-X
A state in which fuel gas is two-dimensionally diffused in the direction of arrow E and supplied to the fuel electrode 2 from the inner surface and bottom surface of the supply groove 4a in the Y-Y cross section in FIG. 4, which is larger than the number of supply grooves in the cross section. It is shown. Here, the number of supply grooves in the Y-Y cross section of FIG. 6 is greater than the number of supply grooves in the X-X plane of FIG. The average diffusion path length, ie, the average diffusion resistance value, becomes smaller in the direction of the arrow. That is, by increasing the number of branched supply grooves in the supply groove, the average diffusion resistance value becomes smaller.However, the same effect can be obtained by using the same structure as described above for the 1L polar base layer for oxidizing gas.

Therefore, when the reactant gas is supplied to the unit reservoir by the operation of the fuel cell having the structure described above, the reactant gas is caused by the electrochemical reaction that occurs when flowing through the electrode base material from the inlet to the outlet. Reactive component 1□: ゛, for example hydrogen,
A large amount of oxygen is consumed in the reaction, and the concentration of the reaction components decreases from the inlet to the outlet, or the average diffusion resistance value decreases gradually, although not directly proportionally at once. Since the reaction component in the reaction gas is supplied to the electrode surface in an equal amount, the current distribution on the electrode surface during operation becomes even.

FIG. 7 is a perspective view of an electrode base material according to a different embodiment of the present invention. In FIG. 7, what type of fuel gas is used as the reaction fluid? lj, the fuel gas flows in the direction of the arrow through the supply groove 4a as a profiteering route, but the depth of the supply groove 4a is gradually deepened from the inlet to the outlet of the fuel gas, and the inside d of the supply 6f^4a
The length of the diffusion path from f+ and the bottom to the fuel electrode 2 is made smaller, and the diffusion resistance is gradually reduced, and the component concentration due to the consumption of reaction components in the reaction gas accompanying the electrochemical reaction during fuel cell operation. By increasing the depth of the supply path in proportion to the decrease in t'a and t1, the diffusion resistance can be reduced, and the current density on the electrode surface can be made equal to tt'6. Note that the same effect can be obtained with the iL electrode base material for oxidant scum due to the similar structure.

In addition, as a method of sequentially decreasing the diffusion resistance of the reactive gas, it can also be obtained by increasing the porosity of the frost and polar base from the inlet to the outlet of the electrode fly through which the reactive gas flows. Figure 8 shows the present invention. This shows a different embodiment of the rib separator type unit battery.
A porous t-polar phase is interposed between the ribbed separator and the ribbed separator.
7 shows a cross-sectional view of the item. In FIG. 8, grooves 10a for supplying fuel gas as a reaction gas are provided on the lower surface of the separator with lips 10 in a direction perpendicular to the direction, while on the upper surface, fuel gas is supplied in a direction parallel to the supply grooves 10a for oxidizing gas. A gas-non-diffusible glue gap separator is provided, which is made up of grooves 10b provided so as to prevent the gas from spreading, and a porous electrode base 14 is interposed between the supply groove 10a and the fuel electrode 2, although not shown. The fuel electrode is in contact with the t# material L7. Similarly, the supply groove 10b of the lipped separator 10 is in contact with the porous t-pole base phase interposed between the oxidizing agent electrode (not shown) and the lipped separator 10. In this example, the fuel gas flows into the supply groove. When flowing through 10a, the fuel gas diffuses within the porous electrode 14 in the direction of arrow F, supplying fuel to the electrode 2.

Therefore, if the supply grooves of the lipped separator are equivalent to the reaction fluid passages having branched supply grooves provided in the electrode base material 4 of the ribbed electrode method as shown in FIG. A structure is obtained in which the reaction fluid passage decreases from the inlet to the outlet, and the same effect as described above is obtained. Further, the same effect can be obtained by increasing the porosity by J [degrees] from the population part to the outlet part of the short frame No. 11 = No. 14.

[The effective spring of IJIJ]

As is clear from the above description, according to the present invention, the reaction fluid containing the non-reacting lJk is transferred from the reaction fluid passage through the porous ?
ti: polar base monthly profit 11 female frost, diffusion in the diffusion path reaching the polar layer (1 is the resistance value, the reaction fluid is IL electricity from the part L1 of the reaction fluid passage of the electrode base material toward the exit part) #1 decreases in proportion to the decrease in the number of reactive components in the reaction fluid, which decreases due to consumption due to chemical reactions. Since the reactive components of the fluid are supplied as equal components 111, there is a moving bed in which uniform current distribution is obtained on the polar layer surface and the life of the fuel cell is extended.

[Brief explanation of the drawing]

Figure 1 is an exploded perspective view showing the configuration of a conventional fuel cell;
The figure is a partial cross-sectional explanatory diagram showing the situation in which the reaction fluid diffuses into the ribbed electrode base village in Figure 1, Figure 3 is a partial perspective view showing the crystal phase of the lip-attached electrode in Figure 1, and Figure 4 is the present invention. FIG. 5 is a partial perspective view showing the crystal phase of the electrode with a refrigeration according to the example of FIG.
□The XX cross section in Fig. 4,
7 is a partial perspective view showing a different embodiment of the present invention, and FIG. 8 is a cross-sectional view showing a situation in which a reaction fluid diffuses in another different embodiment. 2: fuel 1", electrode; 3: oxidizer electrode; 4, 5: electrode crystal phase with refill; 4a, 5a; supply path for reaction fluid; 10: lip separator; 10a, 10b: supply path for reaction fluid;
14: Pole base material. Figure 2. Figure 7

Claims (1)

[Scope of Claims] 1) A structure for supplying a reactive fluid containing a non-reactive component to an electrode layer that performs a power generation function in a fuel cell, the structure comprising a porous electrode in contact with the electrode layer. A base side is provided, and a plurality of reaction fluid passages through which a reaction fluid flows are arranged on the opposite side of the electrode base material from the electrode layer, and a groove 1 facing each reaction fluid passage is provided. The average diffusion resistance value of the two-dimensional diffusion path from the surface of the polar base until the reaction fluid diffuses inside the electrode crystal phase and reaches the electrode layer, and the concentration of the reaction component in the reaction fluid flowing through the reaction fluid path. A structure for supplying a reaction fluid to a fuel cell electrode layer, wherein the characteristics are substantially proportional to each other from an inlet to an outlet of the passage. 2. In the reaction fluid supply structure according to claim 1, the fuel cell electrode layer is characterized in that the diffusion resistance value is determined by the length of the diffusion path inside the electrode crystal phase or the porosity of the electrode base material. reaction fluid supply structure. 3) Reaction fluid supply f1/j according to claim 1
In the structure, multiple reaction fluid passages are formed by forming parallel grooves on the electrode base side, or by forming parallel grooves in a gas-inhibitory plate facing the electrode base material. Features a reactant fluid supply structure to the fuel cell electrode layer.