JPH0594831A - Fuel cell - Google Patents

Abstract

PURPOSE:To provide a fuel cell which can uniform the temperature distribution on the surface of an electrolyte plate, by controlling the flows of the fuel gas and the oxidizer gas indenpendently for the areas on the electrolyte plate. CONSTITUTION:On the periphery of a laminate body made by laminating unit cells which consist of an electrolyte plate and an anode and a cathode provided on both sides of the electrolyte plate, and separators, two pairs of the first holes which consist of penetrating holes 6a to 6m in the laminating direction are provided. Each of the separators 2 has the second holes communicating with the first holes respectively on both sides of separator plates 21. A fuel gas and an oxidizer gas flow in one sides of the pairs of the first holes, pass through the second holes, flow through both sides of the electrolyte plates 1, and finally flow in the other sides of the first holes. By regulating the flow of the reaction gas flowing through the penetrating holes of the first holes, the temperature distribution and the like on the electrolyte plates 1 can be uniformed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated fuel cell capable of efficiently distributing a fuel gas and an oxidant gas, and more particularly, to uniformize the redox reaction on the electrolyte plate to obtain a temperature distribution,
The present invention relates to a stacked fuel cell capable of achieving uniform voltage distribution and reaction product water distribution.

[0002]

2. Description of the Related Art A fuel cell is generally formed by stacking unit cells each having an electrolyte plate and anodes and cathodes provided on both sides thereof with a separator interposed therebetween.

The reaction gas consists of fuel gas and oxidant gas, and the fuel gas is supplied to the anode side of the separator.
On the other hand, the oxidant gas is supplied to the cathode side of the separator. As a result of such supply of the reaction gas, electrons are generated as the electrochemical reaction progresses, and the electrons are taken out to an external circuit to generate electric energy.

In such a so-called laminated fuel cell, a space is provided in the peripheral portion of the laminated body, and the fuel gas and the oxidant gas are allowed to flow between the opposed space portions. ..

However, in the case of the fuel cell having such a structure, since the fuel gas and the oxidant gas flow in only one direction on each electrolyte plate, the contact time between the fuel gas and the oxidant gas is short. It was found that a region where the contact time was long was formed and the redox reaction occurred nonuniformly within the same plane, resulting in nonuniformity of temperature and voltage. Therefore, the power generation efficiency of the entire fuel cell is reduced.

[0006]

[Problems to be Solved by the Invention] In the above circumstances,
Japanese Unexamined Patent Publication (Kokai) No. 62-147664 discloses a unit battery composed of a pair of electrode plates which are opposed to each other with an electrolyte plate interposed therebetween in order to overcome the above-mentioned problem of uneven distribution of temperature, voltage and the like.
In a reaction gas supply method of a fuel cell in which a reaction gas is circulated between the electrode plate and a separator of a fuel cell formed by stacking a plurality of separators via a separator, the reaction gas has a plurality of alternately facing directions. Disclosed is a method which is characterized in that the countercurrent flows which are distributed so as to form a flow and which are adjacent to each other are separated and independent from each other.

However, in the fuel cell for carrying out this reaction gas supply method, since the reaction gases are alternately opposed and flow, the reaction gas supply mechanism and piping are complicated, and the volume and weight of the entire fuel cell are increased. There is a problem of increasing.

Therefore, the present invention is to provide a fuel cell having a simple reaction gas supply mechanism and high power generation efficiency.

Another object of the present invention is to make the temperature distribution and the voltage distribution on the surface of the electrolyte plate uniform by adjusting the flow rates (flow velocities) of the fuel gas and the oxidizing gas on the surface of the electrolyte plate. It is to provide a fuel cell capable.

[0010]

As a result of earnest research in view of the above, the present inventor has found that a fuel composed of a laminated body in which unit cells composed of an electrolyte plate and anodes and cathodes provided on both sides of the electrolyte plate are laminated via a separator. In the battery, a first hole penetrating in the stacking direction and a second hole penetrating in the in-plane direction on both surface sides of the separator are provided, and the fuel gas is circulated in one of the first holes, Of the reaction gas (fuel gas and oxidant gas) by allowing the oxidant gas to flow through the other hole of the
It has been discovered that the supply mechanism can be simplified, the size of the entire fuel cell can be reduced, and the power generation efficiency can be improved. The present inventor also provides a plurality of partition walls on the porous carbon plate arranged in each separator, and causes each of the through holes of the first hole communicating with the second hole opened in the region separated by the partition walls to flow into each through hole. It was discovered that the temperature distribution and the voltage distribution on each electrolyte plate can be made uniform by controlling the flow rates of the fuel gas and the oxidant gas independently. The present invention has been completed based on these findings.

That is, the fuel cell of the present invention comprises a laminated body in which unit cells consisting of an electrolyte plate and anodes and cathodes provided on both sides of the electrolyte plate are laminated through a separator, and the laminated body has a peripheral portion. In, there are two pairs of first holes consisting of a plurality of through holes penetrating in the stacking direction,
Each of the separators is provided with a separator plate and has second holes in the in-plane direction that communicate with the first holes on both sides of the separator plate. It is characterized in that it flows into one of the first holes of the pair and also flows into the other of the first holes of each pair through both sides of each electrolyte plate through the second hole.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a fuel cell according to one embodiment of the present invention has a plurality of square electrolyte plates 1 and square separators 2 alternately stacked, and a manifold 3 at both ends. 4 is attached,
The whole is fixed by screws 5, 5 ...

As shown in FIG. 2, each electrolyte plate 1 has a plurality of openings 11a (three in this embodiment) at each peripheral portion.
~ 11 m is formed. In addition, openings (12, 12 ...) For fixing with screws (5, 5 ...) Are provided at four corners of each electrolyte plate (and also in the peripheral portion if necessary).

The electrolyte plate 1 may be made of any material as long as it is a substance having conductivity for H ⁺ ions and electrons generated by an electrochemical reaction, but Nafion 117 is used for thinning the electrolyte plate 1. It is preferable that a thin layer of Pt is formed on the conductive polymer film as described above by sputtering or the like, and an electrode catalyst layer is formed thereon. Nafion 117 is a kind of ion exchange membrane having a structure represented by the following formula (1) or (2).

[Chemical 1] However, the source of (1) is JP-A-62-195855, and the source of (2) is "Chemical One Point 8 Fuel Cell", Kyoritsu Shuppan Co., Ltd., pp. 55-56.

The electrode catalyst layer is preferably a platinum powder, carbon black or the like dispersed in a Nafion solution and applied on a Pt sputtered thin film.

As shown in FIG. 3, each separator 2 has a square separator 21 and square frame-shaped plate members (hereinafter simply referred to as "frame plates") fixed to both sides thereof with packings 22, 22. ) 23 and 24. As shown in FIG. 4, the opening 11 of the electrolyte plate 1 is provided around the separator 21.
a plurality of openings 21a-2 at positions corresponding to a-11m
1 m is formed. Further, similar to the electrolyte plate 1, screw holes 25, ... Are provided in the four corners and the like.

As shown in FIG. 5 (a), a plurality of openings 23a-23m are formed in the periphery of each frame plate 23 at positions corresponding to the openings 21a-21m of the separator plate 21. There is. Openings 23d, 23e, 23f and 23m, 23 facing each other are provided on the back surface (surface on the side of the separator 21) of the frame plate 23.
k, 23j and a plurality of groove portions 27 communicating between each inner side
d, 27e, 27f and 27m, 27k, 27j are formed, and these grooves contact the separator to form the second hole. In addition, openings 26 for fixing screws at the four corners,
・ ・ Is provided.

As shown in FIG. 5 (b), another frame plate 24
Also has a similar structure, but the openings communicating with the grooves are the openings 23d, 23e, 23f and 23m of the frame plate 23,
Openings 2 facing each other in a direction orthogonal to 3k and 23j
4a, 24b, 24c and 24g, 24h, 24i. In addition, screw fixing openings 29, ... Are provided at four corners and the like. The openings of the separator plate 21 and the frame plates 23 and 24 are aligned to form openings 2a to 2m penetrating the separator 2.

Such frame plates 23 and 24 are used for packing 2.
The separator 2, which is fixed to the separator 21 via 2 and 22, has a structure as shown in FIG. 6 when seen in the AA cross section of FIG. 3, and when it is seen in the BB cross section of FIG. Such a structure is as shown in FIG. 8 when viewed in the cross section CC of FIG. That is, in the peripheral portion of the separator 2, the openings 2a to 2c, 2d to 2f, 2g to 2i, and 2j to 2m penetrate the separator, respectively. These openings 2
The through holes 6a to 6m made of a to 2m extend in the stacking direction of the fuel cell, and the through holes 6a to 6c and 6g to 6i form a pair of first holes 6A and 6B, and the through holes 6d to 6f. And 6j
.About.6 m form another pair of first holes 6C and 6D. In the BB cross section shown in FIG. 7, the groove 2 is formed toward the frame plate 23.
7 is formed, and in the CC cross section shown in FIG. 8, a groove 28 is formed toward the frame plate 24.

Therefore, one of the reaction gases (for example, fuel gas) flows into the openings 2a, 2b, 2c, and the openings 2
When the other of the reaction gases (e.g., oxidant gas) flows into d, 2e, and 2f, the fuel gas flows under the separator 21 and the oxidant gas flows over the separator 21 in FIG. It will be. Electrolyte plate 1 and separator 2
When the electrolyte plate 1 is viewed as the center, the fuel gas flows along the upper side of the electrolyte plate 1 and the oxidant gas flows through the lower side in a direction orthogonal to each other. In this way, since different reaction gases always flow on both sides of each electrolyte plate 1, each of them is a single battery (cell).
Make up.

As shown in FIGS. 9A and 9B, porous carbon plates 7 and 8 are inserted into the central openings of the frame plates 23 and 24, respectively. Porous carbon plates 7 and 8 are frame plates 2
The size is substantially the same as that of the central openings 3 and 24, and the thickness thereof is also the same as the height of the frame plates 23 and 24 + the packing 22.

Each porous carbon plate 7, 8 has a plurality of groove portions 7
, c, ..., 8c, ... are formed,
Partition walls 7a, 7b, 8a, 8b are formed at positions corresponding to the openings 23a-23m, 24a-24m. As the partition walls 7a, 7b, 8a, 8b, a porous carbon plate provided with a partially dense portion can be used. As will be described later, since the partition walls 7a, 7b, 8a, 8b are present, by adjusting the flow rate of the reaction gas flowing into the through holes (first holes) 6a to 6m including the openings 2a to 2m. The flow rate of the reaction gas flowing on the porous carbon plate can be controlled.

In the embodiment shown in FIG. 1, one side surface of the manifold 3 is provided with pipes 31, ...
Is attached to the adjacent side surface, and a pipe 32 for discharging reaction product water and excess oxidant gas is provided on the adjacent side surface ,.
・ Is attached. On the other hand, one side surface (opposite side of the pipes 32, ...) Of the manifold 4 is provided with oxidant gas inflow pipes 41 ,. On the side), pipes 42 for discharging excess fuel gas are attached.

FIG. 10 showing a DD cross section of the manifold 3.
As is apparent from (a), the manifold 3 is provided with holes 3a, 3b, 3c communicating with the pipes 31, ... And holes 3j, 3k, 3m communicating with the pipes 32 ,. , Holes 3a, 3b, 3c are through holes 6a, 6 respectively.
The holes 3j, 3k, 3m communicate with the holes b, 6c, and the through holes 6j, 6k, 6m, respectively. Similarly, the manifold 4 has holes 4d, 4e, 4f to which the pipe 41 is connected.
And holes 4g, 4h, 4i to which the pipe 42 is connected are provided, and the holes 4d, 4e, 4f are through holes 6d, respectively.
The holes 4g, 4h, and 4i communicate with the through holes 6g, 6h, and 6i, respectively.

The other end of the pipe 31 is connected to the fuel gas flow rate varying device 51, and the other end of the pipe 41 is connected to the oxidant gas flow rate varying device 52. The other end of the pipe 32 is connected to a flow rate varying device 53 for the reaction product water to be discharged, and the other end of the pipe 42 is a flow rate varying device 54 for the discharged fuel gas.
Connected to. In each flow rate variable device, the flow rate of the reaction gas flowing through each pipe can be adjusted.

The fuel cell having the above structure can be operated as follows. First, from the flow rate varying device 51, through the pipes 31, ..., Through holes 3a to 3 of the manifold 3.
The fuel gas flows into c and the flow rate changing device 52
Through the pipes 41, ..., and the hole 4d of the manifold 4
The oxidant gas is flown into ~ 4f. Hydrogen gas is preferable as the fuel gas, and hydrogen gas is preferable as the oxidant gas.

The fuel gas flows into the first holes 6a, 6b, 6c penetrating the fuel cell in the stacking direction, and in each separator 2, the groove portions 28a, 28b, 28c of the frame plate 24 are formed.
To flow in the groove of the porous carbon plate housed in the recess of the separator, and then through the grooves 28g, 28h, 28i of the frame plate on the opposite side to the first holes 6g, 6
It flows into h and 6i. Since the split flow of the fuel gas occurs on all the separators 2, all the fuel gas eventually flows through the separator on the porous carbon plate on one side of the electrolyte plate 1.

On the other hand, the oxidant gas flows into the first holes 6d, 6e, 6f penetrating the fuel cell in the stacking direction, and in each separator 2, the groove portions 27d, 27e, 2 of the frame plate 23 are formed.
7f, the flow is divided in the lateral direction, flows through the groove portion of the porous carbon plate housed in the recess of the separator, and passes through the groove portions 27j, 27k, 27m of the frame plate 23 on the opposite side and the first hole 6
It flows into j, 6k, and 6m. Thus, as in the case of the fuel gas, all the oxidant gas flows through the separator on the porous carbon plate on the other side of the electrolyte plate 1.

The fuel gas and the oxidant gas respectively diffuse inside the porous carbon plates 8 and 7 and reach the electrolyte plate 1, where an electrochemical reaction occurs. This is typically H ₂ and O _2.
In the case of H ₂ , H ₂ is separated into H ⁺ and e ⁻ , H ⁺ ions are conducted inside the electrolyte plate 1 and reach the O ₂ side, and H ₂ + 1 / 2O ₂ → H _{2 on} the surface of the electrolyte plate 1. As the reaction of O occurs, electrons are taken out as a current from the terminals of the fuel cell.

The fuel gas inlet and the oxidant gas inlet are provided on different sides in the stacking direction of the fuel cell. However, this is because the temperature distribution and voltage distribution in the stacking direction of the fuel cell are not uniform. This is to prevent uniformization.

By the way, in general, when the fuel gas and the oxidant gas are introduced at a uniform flow rate, as shown in FIG. 14, the longer the contact time between the fuel gas and the oxidant gas, the higher the temperature and the voltage. Also, the voltage distribution becomes non-uniform. Thereby, as shown in FIG. 15, the distribution of the reaction product water becomes non-uniform as well as the distribution of temperature and voltage.

In order to solve this problem, in the fuel cell of the present invention, each porous carbon plate 7, 8 is divided into regions corresponding to the number of first holes on each side,
A plurality of partition walls 7a, 7b, 8a, 8b are formed,
Therefore, the flow rate of the reaction gas in each region of the porous carbon plates 7 and 8 can be controlled by the flow rate varying device to prevent the above-mentioned uneven distribution.

Specifically, as shown in FIG. 11, the flow rate of the fuel gas is increased in the order of F _H1 , F _H2 and F _H3 and the flow rate of the oxidant gas is also in the order of F _O1 , F _O2 and F _O3 . Enlarge. By doing so, as shown in FIG. 13, the electrolyte plate is divided into nine regions 11 to 33 with respect to the flow rate of the reaction gas. Since the contact time (oxidation-reduction reaction time) becomes longer in the direction from the region 11 to the region 33, if the flow rate (flow velocity) of the reaction gas is increased accordingly, the contact time (oxidation-reduction reaction time) is substantially different between the regions. Become the same. Therefore, as schematically shown in FIGS. 11 and 12, the temperature, the voltage, and the distribution of the reaction product water become uniform.

In the above embodiments, the case where the first hole is composed of three through-holes has been described, but the number of through-holes is not limited to this, and may be appropriately selected according to the required level of homogenization of the redox reaction. can do. If a temperature sensor is provided on the porous carbon plate electrode, the flow rate of the reaction gas can be controlled so that the temperature distribution becomes uniform. Note that the flow rate of the reaction gas flowing through each of the through holes of the first hole can be independently controlled, not limited to the above-described mode, so that the flow rate of the reaction gas can be controlled so that the highest efficiency can be obtained. Can be done finely.

[0035]

As described above in detail, in the fuel cell of the present invention, after the fuel gas and the oxidant gas respectively flow into the first hole, the fuel gas and the oxidant gas are diverted by the second hole so that the surface of each electrolyte plate is separated. Since it has a structure for circulating, the use efficiency of the reaction gas is increased and it is advantageous for downsizing of the entire fuel cell.

Further, by independently controlling the flow rates of the fuel gas and the oxidant gas flowing into the respective through holes of the first hole, the fuel flowing through the groove of the porous carbon plate through the second hole of the separator can be controlled. The flow rates of the gas and the oxidant gas are independently different, which allows the flow rate distribution of the reaction gas in the porous carbon plate to be independently controlled in a plurality of regions. Therefore, the temperature on the electrolyte plate,
It has an advantage that the voltage and the distribution of the water produced by the reaction can be made uniform. In this case, by increasing the number of the first holes and the second holes and the number of regions of the porous carbon plate on one side, it is possible to achieve more uniform distribution of temperature, voltage and reaction product water. ..

[Brief description of drawings]

FIG. 1 is a partially exploded perspective view showing the overall structure of a fuel cell according to an embodiment of the present invention.

FIG. 2 is a plan view showing an electrolyte plate used in the fuel cell of the present invention.

FIG. 3 is a perspective view showing a separator used in the fuel cell of the present invention.

FIG. 4 is a plan view showing a central separator of the separator of FIG.

5 shows a pair of frame plates used for the separator of FIG.
(a) is a bottom view showing a frame plate provided on the upper side in FIG. 3, and (b) is a plan view showing a frame plate provided on the lower side in FIG. 3.

6 is a cross-sectional view taken along the line AA of the separator of FIG.

7 is a cross-sectional view taken along line BB of the separator of FIG.

8 is a cross-sectional view taken along line CC of the separator of FIG.

9 shows a porous carbon plate placed on both sides of an electrolyte plate in a state of being housed in a recess of a separator, (a) of FIG.
It is a bottom view which shows the porous carbon plate accommodated in the separator of (a), and (b) is a top view which shows the porous carbon plate accommodated in the separator of FIG. 5 (b).

10 shows the internal structure of both manifolds of the fuel cell, (a) is a sectional view taken along the line DD of FIG. 1, (b) is an E of FIG.
It is a -E sectional view.

FIG. 11 is a schematic diagram showing the flow rate, temperature, and voltage distribution of the reaction gas on the electrolyte plate of the fuel cell of the present invention.

FIG. 12 is a schematic diagram showing the flow rate of reaction gas and the reaction product water on the electrolyte plate of the fuel cell of the present invention.

FIG. 13 is a schematic view showing a region divided by a flow rate of a reaction gas in the electrolyte plate of the fuel cell of the present invention.

FIG. 14 is a schematic diagram showing temperature and voltage distributions on an electrolyte plate when a reaction gas is introduced at a uniform flow rate.

FIG. 15 is a schematic view showing the distribution of reaction product water on the electrolyte plate when the reaction gas flows in at a uniform flow rate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrolyte plate 2 ... Separator 3, 4 ... Manifold 6A-6D ... First hole 6a-6m ... Through hole 7, 8 ... Porous carbon plate 7a, 7b, 8a, 8b ... Partitions 7c, 8c ... Grooves 11a-11m ... Openings forming first holes 21a-21m ... Openings 23a-23m forming first holes ... Openings 24a to 24m forming the first holes ... Openings 27a to 27m forming the first holes ... Grooves forming the second holes 28a to 28m ... Forming the second holes Grooves 31, 32, 41, 42 ... Pipes 51-54 ... Flow rate varying device

Claims (5)

[Claims] 1. A fuel cell comprising a laminated body in which unit cells composed of an electrolyte plate and anodes and cathodes provided on both sides of the electrolyte plate are laminated with a separator interposed therebetween, and the laminated body has a plurality of peripheral portions penetrating in the laminating direction. Has a pair of first holes each of which is a through hole, each separator is provided with a separator plate, and the separators are provided on both sides of the separator plate in the in-plane direction to communicate with the first holes. The fuel gas and the oxidant gas have two holes, respectively, and flow into one of the first holes of each pair, and pass through both sides of each electrolyte plate through the second holes and the first holes of each pair. A fuel cell characterized by flowing into the other of the holes. 2. The fuel cell according to claim 1, wherein a fuel gas inlet and an oxidant gas outlet are provided at one end of the stack, and an oxidant gas inlet and a fuel gas are provided at the other end. A fuel cell having an outlet. 3. The fuel cell according to claim 1 or 2, wherein the flow of gas flowing through each hole is independent. 4. The fuel cell according to claim 3, wherein the flow rate of gas flowing through each of the through holes of the first holes is independently controlled. 5. The fuel cell according to claim 1, wherein the first holes of each pair are provided on opposite side edges of the stack. ..