JPH09219205A - Fuel cell layered product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the nonuniform amount of electrolyte between cells due to the movement of the electrolyte and the deterioration of battery property due to more or less electrolyte in the cells by providing an electrolyte absorbing plate arranged between a cooling plate and a gas supply plate on the cathode side of the cell adjacent thereto. SOLUTION: An electrolyte absorbing plate 20 is arranged between a cooling plate 17 and a gas supply plate 14 on the cathode side of a cell 8e adjacent thereto to absorb electrolyte. When a cell laminate is operated, the electrolyte is moved from a cell 8a on the positive electrode side to the cell 8e on the negative electrode side but the moved electrolyte is absorbed into the electrolyte absorbing plate 20, not accumulated on the cell 8e. In this way, there is no too much electrolyte in the cell 8e and voltage drop due to the increase of diffusive polarization is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell stack for preventing non-uniformity of the amount of electrolyte between unit cells due to electrolyte migration that occurs during operation.

[0002]

2. Description of the Related Art Conventionally, a fuel cell has been known as a device for directly converting the chemical energy of fuel into electric energy. Usually, in a fuel cell, a pair of porous electrode plates are arranged with a matrix holding an electrolyte in between, a fuel gas such as hydrogen is placed on the back surface of one electrode plate, and an oxidant such as air is placed on the back surface of the other electrode plate. Supply each gas,
By utilizing the electrochemical reaction that occurs at this time, electrical energy can be continuously extracted from between the electrodes.

FIG. 7 is an exploded perspective view of a general fuel cell. In the figure, a stack 1 formed by stacking a plurality of unit cells is clamped in the stacking direction by end plates 2 arranged at the upper and lower ends thereof, and the electric energy generated in the stack 1 is It is configured to be taken out from the output terminal 3 provided on the plate 2. Further, the fuel gas 5 and the oxidant gas 6 are supplied to the side surface of the laminated body 1 through the gasket 4.
A manifold 7 is provided for discharging.

FIG. 8 is a sectional view of the above-mentioned conventional fuel cell stack. In the same figure, a plurality of unit cells 8a ... 8e (hereinafter referred to as unit cells 8 when simply referring to the unit cells) constituting the laminated body 1 respectively include an electrolyte layer 9 formed by impregnating an electrolyte, and the electrolyte layer 9. It is composed of a pair of an anode electrode plate 10 and a cathode electrode plate 11 made of a porous carbon material, which are arranged on both sides of the anode electrode 9 with the electrode 9 interposed therebetween. A catalyst layer 12 is formed on each of the surfaces of the anode electrode plate 10 and the cathode electrode plate 11 that contact the electrolyte layer 9. Also,
On the opposite surface of each catalyst layer 12, a fuel gas supply plate 13 or an oxidant gas supply plate 14 each having a gas supply groove for supplying a reaction gas is arranged.

As described above, the conventional laminate 1 has a structure in which the unit cell 8 is sandwiched between the gas supply plates 13 and 14, and is further laminated via the gas impermeable separator 15. Further, since each unit cell 8 generates heat in an operating state, a cooling plate 17 having a heat transfer tube 16 for circulating a cooling medium embedded therein is arranged every time a plurality of unit cells 8 are stacked as a temperature control means. . In the figure, a structure in which five unit cells 8 are sandwiched between two cooling plates 17 is shown.

FIG. 9 is a cross-sectional view of another conventional laminated body.
In the figure, a plurality of unit cells 8 constituting the fuel cell stack 1 are each provided with an electrolyte layer 9 impregnated with an electrolyte.
And a pair of anode electrode plates 18 with a gas supply groove and a cathode electrode plate 19 with a gas supply groove, which are arranged on both sides of the electrolyte layer 9 with the electrolyte layer 9 interposed therebetween. Anode electrode plate 18 and cathode electrode plate 1
A catalyst layer 12 is formed on each of the surface sides of 9 which are in contact with the electrolyte layer 9. Further, the unit cells 8 are stacked in a predetermined number with a gas impermeable separator 15 interposed therebetween. Further, since each unit cell 8 generates heat in an operating state, a cooling plate 17 having a heat transfer tube 16 for circulating a cooling medium embedded therein is arranged every time a plurality of unit cells 8 are stacked as a temperature control means. . In the figure, five unit cells 8 and two cooling plates 1
The structure sandwiched by 7 is shown.

Usually, in the above-mentioned fuel cell stack, the amount of electrolyte retained in each unit cell is mentioned as a factor governing the life. It is generally well known that in a fuel cell, part of the electrolyte is lost from the cell due to the evaporation of the electrolyte into the reaction gas and the oozing from the cell edge due to the volume change of the electrolyte due to start and stop. There is. Therefore, conventionally, measures such as (1) holding the electrolytic mass lost in the battery in advance, and (2) suppressing the amount of electrolyte lost from the battery to the minimum (Japanese Patent Laid-Open No. 61-263061). ) Has been taken.

[0008]

However, not only the one-way loss of electrolyte from the battery as described above, but also the movement of the electrolyte between the stacked unit cells as described below becomes a problem. Has come to be understood.

Further, as shown in FIG. 8 or 9, each unit cell 8 is partitioned by a separator 15. The separator 15 has a function of separating the electrolyte between the individual cells 8 at the same time as separating the gas, but when the operation is long, the electrolyte passes through the separator 15 by electrophoresis,
The electrolyte retention amount of the positive electrode side unit cell 8e gradually increases, while the electrolyte retention amount of the negative electrode side unit cell 8a gradually decreases. When the amount of electrolyte in the unit cell increases or decreases in this way, the voltage decreases due to reaction gas crossover in batteries with reduced electrolyte, and the battery voltage decreases due to increased diffusion polarization in batteries with increased electrolyte. was there. Further, when the increase / decrease amount is large, there is a problem that not only the battery voltage is lowered but also the electrodes are corroded.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a fuel cell laminate in which the cell voltage does not drop even if the electrolyte moves between the cells due to long-term operation. To provide.

[0011]

In order to achieve the above object, claim 1 of the present invention provides a unit cell comprising a pair of an anode electrode and a cathode electrode arranged with an electrolyte layer interposed therebetween, and the unit cell. A plurality of gas supply plates, each of which is provided in contact with the anode electrode and the cathode electrode and has a groove for supplying a reaction gas, and a gas impermeable separator disposed between the adjacent gas supply plates. In the fuel cell stack consisting of, a cooling plate arranged instead of the separator for each of a plurality of stacked unit cells, and a gas supply plate on the cathode side of the unit cell in contact with the cooling plate. And an electrolyte absorbing plate.

According to a second aspect of the present invention, a unit cell composed of a pair of anode and cathode electrodes sandwiching an electrolyte layer, and a reaction gas disposed in contact with the anode electrode and the cathode electrode of the unit cell, respectively. A gas supply plate having a groove capable of supplying a plurality of gas impermeable separators arranged between the gas supply plates adjacent to each other, in each of a plurality of stacked unit cells A cooling plate arranged instead of the separator, an electrolyte absorption plate arranged between the gas supply plate on the cathode side of the unit cell in contact with the cooling plate, and the unit cell in contact with another cooling plate And an electrolyte supply plate disposed between the anode side gas supply plate and the anode side gas supply plate.

According to a third aspect of the present invention, in the fuel cell stack according to the second aspect, a phosphoric acid amount detection probe is attached to each of the electrolyte absorbing plate and the electrolyte replenishing plate.

According to a fourth aspect of the present invention, there is provided a unit cell comprising an anode electrode having a pair of reaction gas supply grooves and a cathode electrode having the reaction gas supply groove, which are arranged with an electrolyte layer interposed therebetween, and a unit cell of the unit cell. A fuel cell stack comprising a plurality of gas-impermeable separators arranged in between, a cooling plate arranged in place of the separator for each of the plurality of unit cells, the cooling plate and the unit cells. And an electrolyte absorption plate disposed between the cathode electrodes of the.

According to a fifth aspect of the present invention, there is provided a unit cell comprising an anode electrode having a pair of reaction gas supply grooves and a cathode electrode having the reaction gas supply groove, which are arranged with an electrolyte layer interposed therebetween, and a unit cell of the unit cell. A fuel cell stack comprising a plurality of gas-impermeable separators arranged in between, a cooling plate arranged in place of the separator for each of the plurality of unit cells, the cooling plate and the unit cells. And an electrolyte replenishing plate arranged between the other cooling plate and the anode electrode of the unit cell.

According to a sixth aspect of the present invention, in the fuel cell stack according to the fifth aspect, a phosphoric acid amount detection probe is attached to each of the electrolyte absorption plate and the electrolyte replenishment plate.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a fuel cell stack according to a first embodiment (corresponding to claim 1) of the present invention. In this embodiment, the cooling plate 17 and the unit cell 8e adjacent to the cooling plate 17 are provided.
Since the configuration in which the electrolyte absorption plate 20 capable of absorbing the electrolyte is arranged between the gas supply plate 14 on the cathode side of the above is different from the conventional fuel cell stack of FIG. 8, the other configurations are the same.
The same parts as those of the conventional example shown in FIG.

According to this embodiment, when the battery stack is operated, the electrolyte moves from the positive cell 8a to the negative cell 8e, but the moved electrolyte is not accumulated in the single cell 8e. It is absorbed by the electrolyte absorption plate 20. Therefore, the electrolyte does not become excessive in the unit cell 8e, and it is possible to prevent a decrease in voltage due to an increase in diffusion polarization.

FIG. 2 is a sectional view of a fuel cell stack according to a second embodiment (corresponding to claim 2) of the present invention. The same parts as those of the conventional example of FIG. The description is omitted.

In this embodiment, the cooling plate 17 and this cooling plate 1
Gas supply plate 14 on the cathode side of the unit cell 8e adjacent to 7
An electrolyte absorbing plate 20 capable of absorbing an electrolyte is arranged between
Further, the cooling plate 17 and the unit cell 8 adjacent to the cooling plate 17
The configuration in which an electrolyte replenishing plate 21 holding an electrolyte is arranged between the gas supply plate 13 on the anode side of a is different from the conventional fuel cell stack of FIG.

According to this embodiment, when the battery stack is operated, the electrolyte moves from the unit cell 8a on the positive side to the unit cell 8e on the negative side, but the moved electrolyte is not accumulated in the unit cell 8e. , And is absorbed by the electrolyte absorption plate 20. Further, the electrolyte can be replenished from the electrolyte replenishing plate 21 to the single cell 8a on the positive electrode side. Therefore, in the unit cell 8e, the electrolyte does not become excessive, and it is possible to prevent a voltage drop due to an increase in diffusion polarization. Also, the unit cell 8a
Therefore, the electrolyte is not deficient, and the voltage drop due to the crossover of the reaction gas can be prevented.

FIG. 3 is a sectional view of a fuel cell stack according to a third embodiment of the present invention (corresponding to claim 3). The same parts as those of the conventional example of FIG. The description is omitted.

In this embodiment, the cooling plate 17 and this cooling plate 1
Gas supply plate 14 on the cathode side of the unit cell 8e adjacent to 7
An electrolyte absorbing plate 20 capable of absorbing an electrolyte is arranged between
Further, the cooling plate 17 and the unit cell 8a adjacent to the cooling plate 17
An electrolyte replenishment plate 21 holding an electrolyte is arranged between the anode side gas supply plates, and an electrolyte mass detection probe 22 is further arranged on the electrolyte absorption plate 20 and the electrolyte replenishment plate 21. Different from the body.

According to this embodiment, when the battery stack is operated, the electrolyte moves from the unit cell 8a on the positive side to the unit cell 8e on the negative side, but the moved electrolyte is not accumulated in the unit cell 8e. , And is absorbed by the electrolyte absorption plate 20. Further, the electrolyte is replenished from the electrolyte replenishing plate 21 to the unit cell 8a on the positive electrode side. Further, the electrolytic mass detection probes 22 arranged on the electrolyte absorbing plate 20 and the electrolyte replenishing plate 21 can detect the electrolytic mass remaining on each plate.

Therefore, the electrolyte does not become excessive in the unit cell 8e, and it is possible to prevent a voltage drop due to an increase in diffusion polarization. Further, in the unit cell 8a, the electrolyte is not deficient, and the voltage drop due to the crossover of the reaction gas can be prevented. Furthermore, by measuring the electrolytic masses remaining on the electrolyte absorption plate 20 and the electrolyte replenishment plate 21, it is possible to predict a decrease in each voltage due to an increase in diffusion polarization and a crossover of the reaction gas. By replacing at least one of the absorbing plate 20 and the electrolyte replenishing plate 21 or by replacing the reaction gas supplied to the battery stack, the flow direction of the electrolyte is reversed, and it becomes possible to operate for a longer time.

FIG. 4 is a sectional view of a fuel cell stack according to a fourth embodiment of the present invention (corresponding to claim 4). The same parts as those of the conventional example of FIG. The description is omitted.

In this embodiment, the cooling plate 17 and this cooling plate 1
7 is different from the conventional fuel cell stack of FIG. 9 in that an electrolyte absorbing plate 20 capable of absorbing an electrolyte is arranged between the cathode electrode plates 19 with gas supply grooves of the unit cell 8e adjacent thereto.

According to this embodiment, when the battery stack is operated, the electrolyte moves from the positive cell 8a to the negative cell 8e, but the moved electrolyte is not accumulated in the single cell 8e. , And is absorbed by the electrolyte absorption plate 20. Therefore, the electrolyte does not become excessive in the unit cell 8e, and it is possible to prevent a decrease in voltage due to an increase in diffusion polarization.

FIG. 5 is a sectional view of a fuel cell stack of a fifth embodiment (corresponding to claim 5) of the present invention. The same parts as those of the conventional example of FIG. The description is omitted.

In this embodiment, the cooling plate 17 and this cooling plate 1
7, an electrolyte absorbing plate 20 capable of absorbing an electrolyte is arranged between the cathode electrode plates 19 with gas supply grooves of the unit cell 8e adjacent to the cooling unit, and the cooling plate 17 and the gas of the unit cell 8a adjacent to the cooling plate 17 are arranged. The configuration in which an electrolyte replenishment plate 21 holding an electrolyte is arranged between the anode electrode plates 18 with supply grooves is different from the conventional fuel cell stack of FIG.

According to this embodiment, when the battery stack is operated, the electrolyte moves from the positive cell 8a to the negative cell 8e, but the moved electrolyte is not accumulated in the single cell 8e. , And is absorbed by the electrolyte absorption plate 20. Further, the electrolyte is replenished from the electrolyte replenishing plate 21 to the unit cell 8a on the positive electrode side.

Therefore, the electrolyte does not become excessive in the unit cell 8e, and it is possible to prevent a voltage drop due to an increase in diffusion polarization. Further, in the unit cell 8a, the electrolyte is not deficient, and the voltage drop due to the crossover of the reaction gas can be prevented.

FIG. 6 is a sectional view of a fuel cell stack according to a sixth embodiment of the present invention (corresponding to claim 6). The same parts as those of the conventional example shown in FIG. The description is omitted.

In this embodiment, the cooling plate 17 and this cooling plate 1
7, an electrolyte absorbing plate 20 capable of absorbing an electrolyte is arranged between the cathode electrode plates 19 with gas supply grooves of the unit cell 8e adjacent to the cooling unit, and the cooling plate 17 and the gas of the unit cell 8a adjacent to the cooling plate 17 are arranged. An electrolyte replenishment plate 21 holding an electrolyte is arranged between anode groove plates 18 with supply grooves, and an electrolyte mass detection probe 22 is arranged on the electrolyte absorption plate 20 and the electrolyte replenishment plate 21. Different from laminated body.

According to the present embodiment, when the battery stack is operated, the electrolyte moves from the unit cell 8a on the positive side to the unit cell 8e on the negative side, but the moved electrolyte is not accumulated in the unit cell 8e. Then, it is absorbed by the electrolyte absorption plate 20.
Further, the electrolyte is replenished from the electrolyte replenishing plate 21 to the unit cell 8a on the positive electrode side. Furthermore, the electrolytic mass detection probes 22 arranged on the electrolyte absorbing plate 20 and the electrolyte replenishing plate 21 can detect the electrolytic mass remaining on each plate.

Therefore, the electrolyte does not become excessive in the unit cell 8e, and it is possible to prevent the voltage from decreasing due to the increase in diffusion polarization. Further, in the unit cell 8a, the electrolyte is not deficient, and the voltage drop due to the crossover of the reaction gas can be prevented. Furthermore, by measuring the electrolytic masses remaining on the electrolyte absorption plate 20 and the electrolyte replenishment plate 21, it is possible to predict a decrease in each voltage due to an increase in diffusion polarization and a crossover of the reaction gas. Whether at least one of the absorption plate 20 and the electrolyte supply plate 21 is replaced,
By changing the reaction gas supplied to the battery stack, the flow direction of the electrolyte is reversed, and the operation can be performed for a long time.

[0037]

As described above, according to the first aspect of the present invention.
According to claim 6, it is possible to prevent unevenness in the amount of the electrolyte between the cells due to the movement of the electrolyte that occurs during the operation of the fuel cell stack, and to prevent the deterioration of the cell characteristics due to the excess or deficiency of the electrolyte in the cell. It can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view of a fuel cell stack according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a fuel cell stack according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a fuel cell stack according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a fuel cell stack according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a fuel cell stack according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view of a fuel cell stack according to a sixth embodiment of the present invention.

FIG. 7 is an exploded perspective view showing a general configuration of a conventional fuel cell.

FIG. 8 is a sectional view showing an example of a conventional fuel cell stack.

FIG. 9 is a cross-sectional view showing another example of a conventional fuel cell stack.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laminated body, 2 ... End plate, 3 ... Output terminal, 4 ... Gasket, 5 ... Fuel gas, 6 ... Oxidizing gas, 7 ... Manifold, 8, 8a-8e ... Single cell, 9 ... Electrolyte layer, 10 ... Anode electrode plate, 11 ... Cathode electrode plate, 12 ... Catalyst layer,
13 ... Fuel gas supply plate, 14 ... Oxidant gas supply plate, 15
... Separator, 16 ... Heat transfer tube, 17 ... Cooling plate, 18 ... Anode electrode plate, 19 ... Cathode electrode plate, 20 ... Electrolyte absorbing plate, 21 ... Electrolyte replenishing plate, 22 ... Electrolyte mass detection probe.

Claims (6)

[Claims] 1. A unit cell comprising a pair of an anode electrode and a cathode electrode arranged with an electrolyte layer sandwiched therebetween, and a groove for supplying a reaction gas, which is arranged in contact with the anode electrode and the cathode electrode of the unit cell, respectively. In a fuel cell stack comprising a number of stacked gas supply plates and gas-impermeable separators arranged between adjacent gas supply plates, instead of the separator for each of a plurality of stacked unit cells. A fuel cell stack comprising: a cooling plate arranged; and an electrolyte absorbing plate arranged between a gas supply plate on the cathode side of the unit cell, which is in contact with the cooling plate. 2. A unit cell comprising a pair of an anode electrode and a cathode electrode arranged with an electrolyte layer sandwiched between them, and a groove for contacting with the anode electrode and the cathode electrode of the unit cell and for supplying a reaction gas, respectively. In a fuel cell stack comprising a number of stacked gas supply plates and gas-impermeable separators arranged between adjacent gas supply plates, instead of the separator for each of a plurality of stacked unit cells. An electrolyte absorption plate arranged between a cooling plate arranged and a gas supply plate on the cathode side of the unit cell in contact with the cooling plate, and a gas supply on the anode side of the unit cell in contact with another cooling plate. A fuel cell stack comprising: an electrolyte supply plate disposed between the plate and the electrolyte supply plate. 3. The fuel cell stack according to claim 2, wherein a phosphoric acid amount detection probe is attached to each of the electrolyte absorption plate and the electrolyte replenishment plate. 4. A unit cell comprising an anode electrode formed with a pair of reaction gas supply grooves and a cathode electrode formed with a reaction gas supply groove, and a gas arranged between the unit cells. In a fuel cell stack comprising a large number of impermeable separators stacked, a cooling plate arranged instead of the separator for each of the plurality of unit cells, and between the cooling plate and the cathode electrode of the unit cell. A fuel cell stack comprising an arranged electrolyte absorption plate. 5. A unit cell composed of an anode electrode having a pair of reaction gas supply grooves and a cathode electrode having a reaction gas supply groove, which are arranged with an electrolyte layer interposed therebetween, and a gas arranged between the unit cells. In a fuel cell stack comprising a large number of impermeable separators laminated, a cooling plate arranged in place of the separator for each of the plurality of unit cells, and between the cooling plate and the cathode electrode of the unit cell. A fuel cell stack comprising: an arranged electrolyte absorption plate; and an electrolyte supply plate arranged between the other cooling plate and the anode electrode of the unit cell. 6. The fuel cell stack according to claim 5, wherein a phosphoric acid amount detection probe is attached to each of the electrolyte absorption plate and the electrolyte supply plate.