WO2013027501A1 - Control device and fuel cell system - Google Patents

Abstract

Provided is a control device provided with: a detection unit that detects the state of an alkaline fuel cell provided with a membrane electrode assembly that includes an anion-conductive electrolyte membrane; a temperature changing unit for changing the temperature of the alkaline fuel cell; a current value changing unit for changing the value of a current flowing in the membrane electrode assembly of the alkaline fuel cell; and a control unit, which is connected to the detection unit, temperature changing unit, and current value changing unit, for controlling the temperature changing unit such that the temperature of the alkaline fuel cell is a prescribed temperature X or greater by increasing the temperature of the alkaline fuel cell according to the detection results from the detection unit and also for controlling the current value changing unit such that a current of a prescribed current value A or greater flows for a given amount of time in the membrane electrode assembly at a temperature of the prescribed temperature X or greater. Also provided is a fuel cell system using the control device.

Description

Control device and fuel cell system

The present invention relates to an alkaline fuel cell control device capable of operating an alkaline fuel cell with high output and power generation efficiency, and a fuel cell system using the same.

The fuel cell includes a membrane electrode assembly (MEA) having a configuration in which an electrolyte membrane is sandwiched between an anode and a cathode as a main part of power generation. Depending on the type of electrolyte membrane, a polymer electrolyte fuel cell (direct fuel) Battery), phosphoric acid fuel cell, molten carbonate fuel cell, solid oxide fuel cell, alkaline fuel cell and the like.

Among the above, the alkaline fuel cell is a fuel cell in which an anion conductive electrolyte membrane (anion exchange membrane) is used as an electrolyte membrane, and charge carriers are hydroxide ions (OH ⁻ ). In an alkaline fuel cell, when an anode electrode and a cathode electrode are electrically connected, a current flows between the anode electrode and the cathode electrode by the following electrochemical reaction, and electric energy can be obtained. That is, when an oxidizing agent (for example, oxygen or air) and water (this water may be water generated at the anode electrode and permeated through the electrolyte membrane) are supplied to the cathode electrode, the following formula (1):
Cathode electrode: 1 / 2O ₂ + H ₂ O + 2e ⁻ → 2OH ⁻ (1)
OH ⁻ is generated by the catalytic reaction represented by This OH ⁻ is transmitted to the anode side through the electrolyte membrane in a hydrated state with water molecules. On the other hand, in the anode electrode, the supplied fuel, for example, H ₂ gas and OH ⁻ transmitted from the cathode electrode are expressed by the following formula (2):
Anode electrode: H ₂ + 2OH ⁻ → 2H ₂ O + 2e ⁻ (2)
To generate water and electrons.

Alkaline fuel cells have advantages such as fewer restrictions on constituent materials such as catalysts and can be manufactured at a lower cost, but unlike other fuel cells, the electrolyte of the electrolyte membrane and catalyst layer is an anion conductive electrolyte. Therefore, the electrolyte membrane and the catalyst layer absorb carbon dioxide (CO ₂ ) in the environment, and OH ⁻ in the electrolyte membrane and the catalyst layer is represented by the following formulas (3) and (4):
CO ₂ + 2OH ⁻ → CO ₃ ²⁻ + H ₂ O (3)
^{_{CO 2 + OH - → HCO 3}} - (4)
It has an inherent problem that it is easily replaced by CO ₃ ²⁻ and / or HCO ₃ ⁻ (hereinafter sometimes referred to as “CO ₂ -derived anion”) by such a reaction. Such an increase in the concentration of CO ₂ -derived anions (decrease in OH ⁻ ion concentration) decreases the anion conductivity of the electrolyte, and as a result greatly increases the cell resistance, leading to a decrease in output and power generation efficiency.

It is known that the problem of the cell resistance increase can be improved by “self-purge” [for example, Hiroyuki Yanagi, and Kenji Fukuta, ECS Transactions, 16 (2), 257-262 (2008) (Non-patent Document 1)]. “Self-purge” refers to a CO ₂ -derived anion contained in an electrolyte membrane and a catalyst layer, which causes a decrease in anion conductivity, for example, by causing a current to flow between the anode and the cathode by operating an alkaline fuel cell. Is moved to the anode electrode, reduced by fuel, and discharged from the anode electrode as CO ₂ gas. Specifically, the following formulas (5) and (6):
H ₂ + CO ₃ ²⁻ → CO ₂ + H ₂ O + 2e ⁻ (5)
H ₂ + 2HCO ₃ ⁻ → 2CO ₂ + 2H ₂ O + 2e ⁻ (6)
Can be expressed as

By the way, in order to effectively use the power generated by the fuel cell, not limited to the alkaline fuel cell, the power generation amount of the fuel cell is adjusted according to the power consumption of the electronic device using the fuel cell as a power source. There is a need. For example, when there is no power consumption of the electronic device, the operation (power generation) of the fuel cell is stopped, or when the power consumption of the electronic device is small, the power generation amount (that is, the operating current value) of the fuel cell is decreased. If the power consumption is large, it is necessary to increase the power generation amount of the fuel cell.

However, in alkaline fuel cells, if the operation is stopped according to the power consumption of the electronic device or the operating current value is reduced, the discharge of CO ₂ gas from the anode electrode by self-purge does not proceed sufficiently, A decrease in output and power generation efficiency due to an increase in cell resistance cannot be sufficiently suppressed. There is also a problem that the reaction overvoltage at the anode electrode increases due to the accumulation of CO ₂ -derived anions on the anode electrode. An increase in reaction overvoltage also causes a decrease in output and power generation efficiency [see Yu Matsui, Morihiro Saito, Aki Masa Tasa, and Minoru Inaba, ECS Transactions, 25 (13), 105-110 (2010) (Non-Patent Document 2). ].

The present invention has been made in view of the above problems, and an object of the present invention is to provide an alkaline fuel cell control device capable of operating an alkaline fuel cell with high output and power generation efficiency, and a fuel cell system using the same. There is to do.

The present invention includes the following.
[1] A detection unit for detecting a state of an alkaline fuel cell including a membrane electrode assembly including an anion conductive electrolyte membrane;
A temperature changing unit for changing the temperature of the alkaline fuel cell;
A current value changing unit for changing a current value flowing through the membrane electrode assembly of the alkaline fuel cell;
Connected to the detection unit, the temperature change unit, and the current value change unit, and according to the detection result by the detection unit, the temperature of the alkaline fuel cell is increased so that the temperature becomes a predetermined temperature X or more. And a control for controlling the current value changing unit so that a current of a predetermined current value A or more flows through the membrane electrode assembly for a predetermined time under a temperature of the predetermined temperature X or higher. And
A control device comprising:

[2] The detection unit includes a temperature of the alkaline fuel cell, the unit time T in _0, the membrane electrode ratio T ₁ / T ₀ of the complex to a predetermined current value A or more current flows time T ₁ And the control device according to [1].

[3] The temperature changing unit includes a heating / cooling device capable of heating and cooling the alkaline fuel cell or a heating device for heating the alkaline fuel cell. Control device.

[4] The control device according to [3], wherein the temperature changing unit includes a device for supplying the heat medium to a flow path for circulating the heat medium, which is included in the alkaline fuel cell.

[5] The control device according to any one of [1] to [4], wherein the current value changing unit includes an electronic load device or a variable resistor connected to the alkaline fuel cell.

[6] The membrane electrode assembly is opposed to the first surface of the anion conductive electrolyte membrane, the first electrode laminated on the first surface of the anion conductive electrolyte membrane, and the first surface of the anion conductive electrolyte membrane. And a second electrode laminated on the second surface,
The control device according to any one of [1] to [5], wherein the temperature changing unit changes a temperature of the first electrode.

[7] The control device according to [6], wherein the first electrode is an anode electrode and the second electrode is a cathode electrode.

[8] The control according to any one of [1] to [7], wherein the predetermined temperature X is 105% to 150% of the temperature of the alkaline fuel cell immediately before the temperature is changed by the temperature changing unit. apparatus.

[9] The control device according to any one of [1] to [8], wherein the predetermined current value A is in a range of 600 to 1000 mA / cm ² .

[10] A fuel cell system comprising a fuel cell unit including the alkaline fuel cell and the control device according to any one of [1] to [9].

According to the control device and the fuel cell system of the present invention, the alkaline fuel cell can be operated with high output and power generation efficiency.

It is the schematic which shows the structure of the control apparatus which concerns on this invention, and the fuel cell system to which this is applied. A state in which a cycle in which a current of a predetermined current value A or more flows through a membrane electrode assembly of an alkaline fuel cell for a certain period of time within a certain unit time is repeated, and the state of changes in the CO ₂ -derived anion concentration at this time is shown. It is a conceptual diagram. Is a conceptual diagram showing changes in the CO ₂ from the anion concentration when flowing only once or more current predetermined current value A to the membrane electrode assembly of the alkaline fuel cell. It is the schematic which shows the control apparatus which concerns on the 1st Embodiment of this invention, and the fuel cell system to which this is applied. It is a schematic sectional drawing which shows an example of the alkaline fuel cell with which a fuel cell part can be equipped. It is a schematic sectional drawing which shows another example of the alkaline fuel cell with which a fuel cell part can be equipped. It is a schematic sectional drawing which shows another example of the alkaline fuel cell with which a fuel cell part can be equipped. It is a schematic top view which shows the 2nd separator which comprises the alkaline fuel cell shown by FIG. It is a schematic top view which shows the state which has arrange | positioned the 2nd wall on the surface of the 2nd separator shown by FIG. It is a schematic top view which shows another example of a 2nd separator.

FIG. 1 is a schematic diagram showing a configuration of a control device according to the present invention and a fuel cell system to which the control device is applied. As shown in FIG. 1, the control device of the present invention is connected to a fuel cell unit 10 including an alkaline fuel cell, and is connected to the fuel cell unit 10; a detection unit 20 for detecting the state of the alkaline fuel cell. A temperature changing unit 30 for changing the temperature of the alkaline fuel cell; a current value changing unit for changing the current value of the current connected to the fuel cell unit 10 and flowing through the membrane electrode assembly of the alkaline fuel cell 40; and basically a control unit 50 connected to the detection unit 20, the temperature changing unit 30, and the current value changing unit 40. The control unit 50 receives a detection result (information signal) related to the state of the alkaline fuel cell from the detection unit 20, and raises the temperature of the alkaline fuel cell according to the received detection result, thereby causing the temperature to reach a predetermined temperature. The temperature changing unit 30 is controlled so as to be equal to or higher than X, and the current value changing unit 40 is controlled so that a current equal to or higher than the predetermined current value A flows through the membrane electrode assembly for a predetermined time at a temperature equal to or higher than the predetermined temperature X. To do.

The fuel cell system of the present invention includes a fuel cell unit 10 including an alkaline fuel cell, and the control device. The fuel cell unit 10 includes a detection unit 20, a temperature changing unit 30, and a current value of the control device. Connected to the changing unit 40. The alkaline fuel cell constituting the fuel cell unit 10 includes a membrane electrode assembly having an anion conductive electrolyte membrane.

In the control device and the fuel cell system of the present invention, a current of a predetermined current value A or more is “a certain time” in the membrane electrode assembly of the alkaline fuel cell included in the fuel cell unit 10 at a temperature of the predetermined temperature X or higher. The fuel cell is controlled to flow. FIG. 2 is a conceptual diagram showing a state in which a cycle in which a current of a predetermined current value A or more flows for a certain period of time within a unit time is repeated in a membrane electrode assembly of an alkaline fuel cell. Referring to FIG. 2, in the present invention, “a current of a predetermined current value A or more flows through the membrane electrode assembly for a certain period of time” means that an alkaline fuel cell supplies power to an electronic device using this as a power source. This means that a current equal to or greater than the predetermined current value A flows for a certain period of time within the unit time T ₀ regardless of whether or not (that is, whether or not power is being generated). Preferably, as shown in FIG. 2, a cycle of unit time T ₀ including a certain time during which a current of a predetermined current value A or more flows (that is, a current of a predetermined current value A or more is intermittently generated). (Flowing state) is repeated.

The above “regardless of whether the alkaline fuel cell is supplying power to an electronic device using this as a power source (that is, whether or not it is generating power)” means that a current of a predetermined current value A or more is This means that it does not matter whether it is due to power generation according to a request from an electronic device or whether the control device is forced to flow.

In the case where a cycle of unit time T ₀ including a certain time during which a current of a predetermined current value A or more is flowing is repeated two or more times, all the above certain times may have the same time length, or two or more kinds Different time lengths may be included. Further, the current flowing through the membrane electrode assembly is not particularly limited as long as it is equal to or greater than the predetermined current value A, and may all be the same current value or may include two or more different current values. A current greater than or equal to the predetermined current value A may be supplied a plurality of times within the unit time T ₀ .

In FIG. 2, a cycle of a unit time T ₀ including a certain time during which a current of a predetermined current value A or more flows in the membrane electrode assembly of an alkaline fuel cell is repeated (a current of a predetermined current value A or more is The state of the change in the CO ₂ -derived anion concentration when the gas flows intermittently is also shown. As shown in the figure, by repeating a cycle of unit time T ₀ including a certain time during which a current of a predetermined current value A or more flows, self-purge with a large current of a predetermined current value A or more is repeated intermittently. Therefore, the CO ₂ -derived anion concentration in the membrane electrode assembly can be maintained at a substantially low level, and the accumulation of CO ₂ -derived anions can be suppressed. Thereby, the problem of increase in cell resistance and increase in reaction overvoltage at the anode electrode can be improved, and the output and power generation efficiency of the alkaline fuel cell can be improved.

On the other hand, FIG. 3 shows only one unit time T ₀ including a certain time during which a current of a predetermined current value A or more flows through the membrane electrode assembly of an alkaline fuel cell (a current of a predetermined current value A or more is It shows conceptually how the CO ₂ -derived anion concentration changes when it flows only once). Such a case is, for example, a case where a current of a predetermined current value A or more is forcibly supplied by the control device, and thereafter the control device and the alkaline fuel cell are not operated; When the alkaline fuel cell generates power at a current lower than a predetermined current value A after that; after the alkaline fuel cell generates power at a current higher than the predetermined current value A, and thereafter The alkaline fuel cell generates power with a current less than a predetermined current value A, or the alkaline fuel cell is stopped.

In the present invention, “a current of a predetermined current value A or more flows through the membrane electrode assembly for a certain period of time” includes a case where the current of a predetermined current value A or more flows as shown in FIG. Although there may be a case where there is only one unit time T ₀ , such a cycle of unit time T ₀ is preferably repeated as shown in FIG. This is because the CO ₂ -derived anion concentration in the membrane electrode complex can be maintained substantially always low. When there is only one unit time T ₀ including a certain time during which a current greater than or equal to the predetermined current value A flows, a sufficiently high output or power is generated when the alkaline fuel cell generates power after the unit time T _0. It may be difficult to obtain power generation efficiency. However, when the alkaline fuel cell does not generate power after the CO ₂ -derived anion is accumulated in the electrolyte membrane and the catalyst layer to such an extent that the output and power generation efficiency are remarkably reduced, a predetermined current value A or more is obtained. There may be only one unit time T ₀ including a certain time during which the current flows.

Here, one of the features of the control device and the fuel cell system of the present invention is that the temperature change unit 30 is controlled together with the current value change unit 40 to raise the temperature of the alkaline fuel cell to a predetermined temperature X or higher. The temperature is controlled so that a current of a predetermined current value A or more flows through the membrane electrode assembly for a predetermined time at the temperature. The predetermined temperature X is a temperature higher than the temperature of the alkaline fuel cell immediately before raising the temperature (hereinafter also referred to as the immediately preceding temperature). The value of current that can be passed through the membrane electrode assembly increases as the temperature of the alkaline fuel cell increases. Therefore, by adjusting the temperature of the alkaline fuel cell to a high temperature range, a current value equal to or higher than the predetermined current value A is realized more than when the temperature of the alkaline fuel cell is maintained at the immediately preceding temperature. In addition to being easy, the current value of the current that flows for a certain period of time can be increased. Since a larger current can flow, the amount of CO ₂ gas discharged from the anode electrode per unit time can be increased, and as a result, the concentration of CO ₂ -derived anions in the membrane electrode assembly can be reduced earlier. Can be made.

In the present invention, basically, when the concentration of the CO ₂ -derived anion in the membrane electrode assembly is relatively high, the temperature of the alkaline fuel cell is set to a predetermined temperature X or more, and the membrane electrode assembly has a predetermined current value A. The above current is controlled so as to flow for a certain period of time. However, when the concentration of anion derived from CO ₂ in the membrane electrode assembly is relatively high, the electrolyte in the electrolyte membrane or the electrode catalyst layer is mainly carbonate ion type. Therefore, even if the temperature of the alkaline fuel cell is raised, these deteriorations are unlikely to occur.

According to the present invention, as described above, regardless of whether the alkaline fuel cell is generating electricity (in other words, the power consumption of the electronic device using the alkaline fuel cell as a power source), the membrane electrode assembly Since the concentration of CO ₂ -derived anions in the inside can be kept substantially low at all times, an alkaline fuel cell can generate power while suppressing an increase in cell resistance and an increase in reaction overvoltage at the anode electrode. Thereby, output and power generation efficiency can be improved. Further, according to the present invention, as described above, the CO ₂ -derived anion concentration in the membrane electrode assembly can be reduced earlier, so that the length of time during which a current greater than or equal to the predetermined current value A flows (that is, Since the fixed time T ₂ ), which will be described later, can be shortened, the effect of improving the output and power generation efficiency can be obtained earlier, and it is advantageous in further reducing the surplus power and improving the output and power generation efficiency.

Furthermore, the control device of the present invention and the fuel cell system to which the control device is applied can exhibit the following operational effects.

[I] Alkaline fuel cell operation can be stopped with the CO ₂ -derived anion concentration in the membrane electrode assembly being low, and the CO ₂ -derived anion concentration can be kept low even during shutdown. Therefore, the start-up (start-up time) when starting up the alkaline fuel cell can be accelerated (that is, the time required to reach the required power generation amount can be shortened).

Note that the temperature and current value control by the control device of the present invention is performed at the time of steady operation of the alkaline fuel cell (during power generation), at the start-up after operation stop (initial operation stage), or at the standby operation of the alkaline fuel cell. It can be implemented in any one or more operation modes (state in which power is not supplied to the electronic device).

[Ii] According to the present invention in which the operating current value is controlled to increase for a certain period of time within the unit time T ₀ , as compared with the case where the operating current value is continuously increased, surplus power (required by the electronic device) Occurrence of electric power exceeding the amount to be generated) can be suppressed. This also contributes to improvement of output and power generation efficiency. Note that, in order to suppress a decrease in output and power generation efficiency due to the surplus power, surplus power may be stored in a storage battery (not shown), for example, even when the operating current value is intermittently increased.

Further, as described above, when the concentration of the CO ₂ -derived anion in the membrane electrode assembly is relatively high, deterioration of the electrolyte in the electrolyte membrane and the electrode catalyst layer hardly occurs even when the temperature of the alkaline fuel cell is increased. In view of the fact that when the concentration of anion derived from CO ₂ decreases and the electrolyte membrane or electrolyte mainly becomes OH ⁻ type, OH ⁻ tends to attack and degrade the cation site of the electrolyte membrane or electrolyte at a high temperature. In addition, control is performed so that the operating current value increases for a certain period of time within the unit time T ₀ , and only for the certain period of time, or only for the certain period of time and for the specified period before and after this period (the shorter the specified period, the better) It is preferable to control the temperature to be equal to or higher than the predetermined temperature X.

[Iii] According to the aspect in which the operation current value is intermittently increased, the high output and the power generation efficiency are maintained for a long time as compared with the case where the operation current value is increased only once, for example. be able to.

[Iv] According to the present invention which controls to increase the operating current value for a certain period of time within the unit time T ₀ , compared with the case where such control is not performed at all (no large current is passed), the alkaline type The amount of water produced at the anode of the fuel cell can be increased [see the above formula (2)]. As a result, the water content of the anion conductive electrolyte membrane can be maintained at a moderately high level and the anion conductive resistance can be maintained at a low level. This also contributes to improvement of output and power generation efficiency and shortening of startup time.

On the other hand, when the temperature of the alkaline fuel cell is increased in accordance with the control according to the present invention, the anode electrode is in an appropriate dry state due to a decrease in the relative humidity of the fuel. Even when a current of a predetermined current value A or more is applied to the composite, flooding of the anode electrode is difficult to occur, and according to an aspect in which the operating current value is intermittently increased, the flooding suppression effect is maintained for a long time. can do.

In the present invention, “the state of the fuel cell” detected by the detection unit 20 refers to an index (parameter) that can evaluate the CO ₂ -derived anion concentration in the membrane electrode assembly. Specific examples of the battery include the following.

[A] is in the unit time T in _0, the ratio T ₁ / T ₀ of the time predetermined current value A or more current flows through the membrane electrode assembly T _1,
[B] CO ₂ -derived anion concentration (or CO ₃ ²⁻ concentration of these) in the anion conductive electrolyte membrane,
[C] pH of the anion conductive electrolyte membrane,
[D] resistance value of the anion conductive electrolyte membrane,
[E] Output voltage value of alkaline fuel cell.

Among the above, since it is an index that affects the CO ₂ -derived anion concentration in the membrane electrode complex and the detection method is relatively easy, the detection unit 20 is derived from CO ₂ in the membrane electrode complex. It is preferable to detect the above [a] as a parameter for evaluating the anion concentration. In addition to the parameters for evaluating the CO ₂ -derived anion concentration in the membrane electrode assembly, the detection unit 20 can usually detect the temperature of the alkaline fuel cell and the value of the current flowing through the membrane electrode assembly.

Hereinafter, the control device and the fuel cell system of the present invention will be described in more detail with reference to embodiments. In all of the embodiments described later, the above [a] is detected as the state of the alkaline fuel cell.

FIG. 4 is a schematic diagram illustrating a control device according to the present embodiment and a fuel cell system to which the control device is applied. The control device and the fuel cell system are connected to an electronic device (electronic device 60) to which power is supplied. The structure of is shown. The control device according to the present embodiment includes the above-described detection unit 20 connected to a fuel cell unit 10a as a fuel cell unit 10 including an alkaline fuel cell including a membrane electrode assembly having an anion conductive electrolyte membrane. a] Detection unit 20a for detecting (a ratio T ₁ / T _{0 of} time T _{1 in which} a current equal to or greater than a predetermined current value A flows in the membrane electrode assembly within a certain unit time T ₀ ); connected to the fuel cell unit 10a A temperature controller 30a for changing the temperature of the alkaline fuel cell as the temperature changing unit 30; connected to the fuel cell unit 10a and connected in parallel to the electronic device 60 Electronic load device 40a for changing the current value of the current flowing through the membrane electrode assembly of the alkaline fuel cell as changing unit 40; and detection unit 20a, temperature controller 30a, and electronic load device 40 The temperature controller 30a is controlled by increasing the temperature of the alkaline fuel cell according to the detection result by the detection unit 20a so that the temperature becomes equal to or higher than the predetermined temperature X, and the predetermined temperature X A control unit 50a is provided for controlling the electronic load device 40a so that a current of a predetermined current value A or more flows through the membrane electrode assembly for a certain period of time under the above temperature.

In the present embodiment, the detection unit 20a detects the value of the current flowing through the membrane electrode assembly [more specifically, the value of the current flowing between the first electrode (for example, the anode electrode) and the second electrode (for example, the cathode electrode) of the membrane electrode assembly. ] An ammeter connected to the fuel cell unit 10a (alkaline fuel cell) and a temperature sensor (thermometer) for measuring the temperature of the fuel cell unit 10a (alkaline fuel cell). I have. The detection unit 20a also includes a time measuring means (such as a timer) for measuring the unit time T ₀ and the time T ₁ when a current equal to or greater than the predetermined current value A flows through the membrane electrode assembly, and the current value and the time T. ₀ , T ₁ storing means (memory etc.) is provided. However, the time measuring means and the storage means can be included in the control unit 50a.

Examples of the temperature controller 30a include a heating / cooling device that can heat and cool the alkaline fuel cell, and a heating device (heater, etc.) for heating the alkaline fuel cell. As the heating / cooling device, a device for heating and cooling an alkaline fuel cell using a heat medium as described later can be preferably used. As described above, when a current of a predetermined current value A or higher is passed through the membrane electrode assembly, it is necessary to raise the temperature of the alkaline fuel cell to a predetermined temperature X or higher. In a state where it is not necessary to pass a current greater than or equal to the current value A (a state where the CO ₂ -derived anion concentration is sufficiently low, etc.), from the viewpoint of suppressing deterioration of the electrolyte in the electrolyte membrane or the electrode catalyst layer, it is preferably less than a predetermined temperature X Therefore, it is preferable to use a heating / cooling device capable of heating and cooling as the temperature controller 30a.

Here, in the present embodiment, the temperature controller 30a can set the temperature of at least the first electrode (for example, the anode electrode) and the second electrode (for example, the cathode electrode) to a predetermined temperature X or higher. For example, a heating / cooling device or a heating device connected to both the first electrode and the second electrode (a heating / cooling device or a heating device connected to the first electrode and a second electrode) A heating / cooling device or a heating device may be provided separately), and a temperature-controlled thermostat housing the entire fuel cell unit 10a (alkaline fuel cell).

Conventionally known devices can be used as the electronic load device 40a, and a variable resistor can also be used. The controller 50a is not particularly limited as long as it can control the temperature controller 30a and the electronic load device 40a according to the detection result of the detector 20a, and may be a personal computer, for example.

In addition, regarding the connection between the fuel cell unit 10a and the electronic device 60, these may be connected via a converter (step-up circuit).

In the present embodiment, the detection section 20a detects always preferably the time rate T ₁ / T _0, it is determined by the control unit 50a the time ratio T ₁ / T ₀ is less than the predetermined time rate W _T In this case, the control unit 50a determines that the temperature of the alkaline fuel cell (at least the first electrode and the second electrode) is equal to the predetermined temperature X, regardless of whether the fuel cell unit 10a performs power generation (power supply to the electronic device 60). The temperature controller 30a is controlled so as to rise to the above, and at a temperature equal to or higher than the predetermined temperature X, a current equal to or higher than a predetermined current value A is supplied to the membrane electrode assembly (between the first electrode and the second electrode) for a predetermined time. The electronic load device 40a is controlled to flow (for example, to obtain a current waveform pattern as shown in FIG. 2).

More specifically, when the control unit 50a determines that the time ratio T ₁ / T ₀ is less than the predetermined time ratio W _T , the first electrode (anode electrode) is fuel and the second electrode (cathode electrode). ) While controlling the temperature controller 30a so that the temperature of the alkaline fuel cell (at least the first electrode and the second electrode) is raised to a predetermined temperature X or higher by the controller 50a. By increasing the load current flowing through the electronic load device 40a at a temperature equal to or higher than the predetermined temperature X, the first electrode-the second electrode for a certain time T ₂ such that T ₂ / T ₀ ≧ W _T is satisfied. A current of a predetermined current value A or more is passed between the two electrodes. Preferably, the time ratio T ₁ / T ₀ is constantly detected so that a cycle of unit time T ₀ including a certain time during which a current of a predetermined current value A or more flows is repeated. Also, preferably, during the predetermined time T _2, the first electrode - after flowing over the current predetermined current value A between the second electrode (i.e., out of the unit time T _0, the time other than the predetermined time T ₂₎ Controls the temperature regulator 30a so that the temperature of the alkaline fuel cell is less than the predetermined temperature X, and preferably the temperature just before the above.

As described above, in the present invention, regardless of whether the fuel cell unit 10a performs power generation (power supply to the electronic device 60) in order to achieve a substantially always low CO ₂ -derived anion concentration, Preferably, a state where a current of a predetermined current value A or more flows through the membrane electrode assembly for a certain period of time is maintained, for example, a unit time T ₀ including a certain time during which a current of a predetermined current value A or more flows. When the above cycle is repeated, at least part of the flowing current may be due to power generation performed in accordance with the request of the electronic device 60. That is, when power generation is performed in accordance with the request of the electronic device 60 and a current greater than or equal to the predetermined current value A flows through the membrane electrode assembly, the control unit 50a is forced to exceed the predetermined current value A according to the control flow. However, even in this case, since a state where a current of a predetermined current value A or more flows in the membrane electrode assembly for a certain period of time is maintained, the CO ₂ -derived anion is substantially always low. Concentration is realized.

The unit time T ₀ is not particularly limited, and can be, for example, in the range of about 10 to 30 minutes. The predetermined time ratio W _T is determined in consideration of a desired output, a degree of improvement in power generation efficiency, a degree of improvement in start-up time, and the like, and may be selected from a range of, for example, 5 to 20% (eg, 10%). it can.

The predetermined current value A is also determined in consideration of the desired output, the degree of improvement in power generation efficiency, the degree of improvement in start-up time, etc., and is in the range of 400 to 1000 mA / cm ² , preferably in the range of 600 to 1000 mA / cm ² , More preferably, it can be selected from the range of 700 to 1000 mA / cm ² . The current value (both the current value detected by the detection unit and the current value of the current that flows for a certain time (T ₂ )) in the present invention is a membrane electrode complex [first electrode (anode electrode) −second electrode]. The value obtained by dividing the amount of current flowing between (cathode electrodes) by the projected area of the cathode electrode on the electrolyte membrane.

The value of “current greater than or equal to the predetermined current value A” that is passed through the membrane electrode assembly for a certain time (time length T ₂ ) according to the detection result by the detection unit 20a is detected by the detection unit 20a as “unit time T _0. In this case, it may be the same as the “predetermined current value A” set in the ratio T ₁ / T _{0 of} the time T ₁ when the current of the predetermined current value A or more flows through the membrane electrode assembly. It can be large. T ₂ is normally set to be longer than T ₁ .

The predetermined temperature X may be any temperature that is higher than the immediately preceding temperature and that can realize a current value equal to or higher than the predetermined current value A, and is preferably 105% to 150% of the immediately preceding temperature, preferably Is a temperature of 110% to 125% of the immediately preceding temperature.

[Alkaline fuel cell]
Next, an alkaline fuel cell that can be included in the fuel cell unit 10a will be described in detail. FIG. 5 is a schematic cross-sectional view showing an example of an alkaline fuel cell that can be provided in the fuel cell unit 10a. An alkaline fuel cell 100 shown in FIG. 5 includes an anion conductive electrolyte membrane 101, a first electrode (anode electrode) 102 laminated on the first surface of the anion conductive electrolyte membrane 101, and a first electrode of the anion conductive electrolyte membrane 101. A membrane electrode assembly (MEA) composed of a second electrode (cathode electrode) 103 laminated on a second surface opposite to the first surface; laminated on the first electrode 102, comprising at least a fuel receiving portion 106 for receiving fuel A first separator 104; a second separator 105 stacked on the second electrode 103, which includes at least an oxidant receiving portion 107 for receiving an oxidant.

The first electrode 102 and the second electrode 103 are provided to face each other with the anion conductive electrolyte membrane 101 interposed therebetween. More specifically, the first electrode 102 and the second electrode 103 are laminated at substantially the center of the surface of the anion conductive electrolyte membrane 101 so that the positions in the surface of the anion conductive electrolyte membrane 101 coincide. A gasket 150 (for example, a layer made of an elastic resin such as silicone rubber or a cured material layer of a curable resin such as an epoxy resin) is provided at the periphery of the electrode in order to prevent intrusion of air or the like from the electrode end face. Is provided.

(1) Anion-conducting electrolyte membrane The anion-conducting electrolyte membrane 101 is electrically insulative in order to conduct OH ^- ions and prevent a short circuit between the first electrode 102 and the second electrode 103. Although it does not restrict | limit as long as it has, it can use an anion conductive solid polymer electrolyte membrane suitably. Preferable examples of the anion conductive solid polymer electrolyte membrane include, for example, perfluorosulfonic acid type, perfluorocarboxylic acid type, styrene vinyl benzene type, quaternary ammonium type solid polymer electrolyte membrane (anion exchange membrane). It is done. Further, a membrane obtained by impregnating a concentrated potassium hydroxide solution into polyacrylic acid, an anion conductive solid oxide electrolyte membrane, or a layered double hydroxide exhibiting hydroxide conductivity can also be used as the anion conductive electrolyte membrane 101. .

The anion conductive electrolyte membrane 101 preferably has an anion conductivity of 10 ⁻⁵ S / cm or more, and an electrolyte membrane having an anion conductivity of 10 ⁻³ S / cm or more such as a perfluorosulfonic acid polymer electrolyte membrane. It is more preferable to use The thickness of the anion conductive electrolyte membrane 101 is usually 5 to 300 μm, preferably 10 to 200 μm.

(2) 1st electrode and 2nd electrode It laminates | stacks on the 1st surface of the anion conductive electrolyte membrane 101, and is laminated | stacked on the 2nd surface facing the 1st electrode 102 which functions as an anode pole at the time of electric power generation, and a 1st surface. The second electrode 103 functioning as a cathode electrode during power generation includes at least a catalyst layer composed of a porous layer containing a catalyst and an electrolyte. These catalyst layers are laminated in contact with the surface of the anion conductive electrolyte membrane 101. The first electrode 102 catalyst (anode catalyst) is fuel and OH supplied to the first electrode 102 ^- from an anion, which catalyzes a reaction to produce water and electrons. Electrolyte contained in the catalyst layer of the first electrode 102 (anode catalyst layer), OH has been conducted from the anion conducting electrolyte membrane 101 ^- has the function of conducting anion to the catalyst reaction sites. On the other hand, the catalyst (cathode catalyst) of the second electrode 103 catalyzes the reaction of generating OH 2 ⁻ anion from the oxidant and water supplied to the second electrode 103 and the electrons transferred from the first electrode 102. . The electrolyte contained in the catalyst layer (cathode catalyst layer) of the second electrode 103 has a function of conducting the generated OH ⁻ anion to the anion conductive electrolyte membrane 101.

As the anode catalyst and the cathode catalyst, conventionally known ones can be used. For example, platinum, iron, cobalt, nickel, palladium, silver, ruthenium, iridium, molybdenum, manganese, these metal compounds, and these metals And fine particles made of an alloy containing two or more of the above. The alloy is preferably an alloy containing at least two of platinum, iron, cobalt, and nickel. For example, platinum-iron alloy, platinum-cobalt alloy, iron-cobalt alloy, cobalt-nickel alloy, iron-nickel alloy, etc. And iron-cobalt-nickel alloys. The anode catalyst and the cathode catalyst may be the same or different.

The anode catalyst and the cathode catalyst are preferably those supported on a carrier, preferably a conductive carrier. Examples of the conductive carrier include carbon black such as acetylene black, furnace black, channel black, and ketjen black, and conductive carbon particles such as graphite and activated carbon. In addition, carbon fibers such as vapor grown carbon fiber (VGCF), carbon nanotube, carbon nanowire, and the like can be used.

As the electrolyte contained in the catalyst layers of the first electrode 102 and the second electrode 103, the same electrolyte as that constituting the anion conductive solid polymer electrolyte membrane can be used. The content ratio of the catalyst to the electrolyte in each catalyst layer is usually about 5/1 to 1/4, and preferably about 3/1 to 1/3 on a weight basis.

The first electrode 102 and the second electrode 103 may each include a gas diffusion layer laminated on the catalyst layer. The gas diffusion layer has a function of diffusing the supplied fuel or oxidant in the surface and a function of transferring electrons to and from the catalyst layer.

The gas diffusion layer can be a porous layer having electrical conductivity. Specifically, for example, carbon paper; carbon cloth; epoxy resin film containing carbon particles; metal or alloy foam, sintered body Or it can be a fiber nonwoven fabric. The thickness of the gas diffusion layer is preferably 10 μm or more in order to reduce the diffusion resistance of the fuel or oxidant in the direction perpendicular to the thickness direction (in-plane direction). In order to reduce, it is preferable that it is 1 mm or less. The thickness of the gas diffusion layer is more preferably 100 to 500 μm.

(3) First Separator and Second Separator The first separator 104 and the second separator 105 are members for supplying fuel and oxidant to the first electrode 102 and the second electrode 103, respectively. The first separator 104 can be a member having at least a concave portion constituting the fuel receiving portion 106 on the surface on the anion conductive electrolyte membrane 101 side, and the second separator 105 has a concave portion constituting the oxidant receiving portion 107 as an anion. It can be a member having at least the conductive electrolyte membrane 101 side surface.

The concave portion constituting the fuel receiving portion 106 and the concave portion constituting the oxidant receiving portion 107 are the anion conductive electrolytes of the first separator 104 and the second separator 105 in the region where the first electrode 102 and the second electrode 103 are laminated, respectively. Provided on the surface of the film 101 side.

The recesses constituting the fuel receiving part 106 and the oxidant receiving part 107 can each be, for example, one or two or more flow channel grooves having a serpentine shape, a line shape, or other shapes. The recesses may be formed to spread over a relatively large area. The fuel introduced into the fuel receiving part 106 is supplied to the first electrode 102 disposed immediately above it, and the oxidant introduced into the oxidant receiving part 107 is supplied to the second electrode 103 disposed immediately below it. Is done. A fuel supply pipe and a fuel discharge pipe may be connected to the inlet side end portion and the outlet side end portion of the concave portion constituting the fuel receiving portion 106, respectively. Similarly, an oxidant supply pipe and an oxidant discharge pipe may be connected to the inlet side end part and the outlet side end part of the concave part constituting the oxidant receiving part 107, respectively.

The material of the first separator 104 and the second separator 105 is not particularly limited, but is preferably a conductive material such as a carbon material, a conductive polymer, various metals, and an alloy typified by stainless steel. By using a conductive material, it is possible to give these separators a current collecting function, that is, a function as a take-out electrode for transferring and receiving electrons with an electrode in contact with the separator. However, the first separator 104 and the second separator 105 may be made of a non-conductive material such as a plastic material, and an anode current collecting layer and a cathode current collecting layer may be provided separately. In this case, these current collection layers are arrange | positioned, for example between an electrode and a separator.

As the first separator 104 and the second separator 105, a so-called bipolar plate having both a fuel receiving portion and an oxidant receiving portion can be used. In this case, the bipolar plate has a concave portion constituting the fuel receiving portion 106 on one main surface (first surface), and the oxidant receiving portion 107 on the other main surface (second surface) opposite to the first surface. Has a recess. When this bipolar plate is used as the first separator 104, the bipolar plate is laminated on the first electrode 102 so that the first surface thereof is on the anion conductive electrolyte membrane 101 side. When a bipolar plate is used as the second separator 105, it is laminated on the second electrode 103 so that its second surface is on the anion conductive electrolyte membrane 101 side. The use of the bipolar plate is advantageous for thinning the stack structure when, for example, a stack structure is constructed by stacking a plurality of single cells.

FIG. 6 is a schematic cross-sectional view showing another example of an alkaline fuel cell that can be provided in the fuel cell unit 10a. The fuel cell unit 10a may include an alkaline fuel cell 200 as shown in FIG. The alkaline fuel cell 200 shown in FIG. 6 has an anode having a volume of the catalyst layer (anode catalyst layer) of the first electrode 102 larger than that of the catalyst layer (cathode catalyst layer) of the second electrode 103. Except that the weight of the anode catalyst contained in the catalyst layer is larger than the weight of the cathode catalyst contained in the cathode catalyst layer, it is the same as the alkaline fuel cell 100 of FIG. As a result, the amount of CO ₂ gas discharged per unit time from the first electrode (anode electrode) 102 can be increased, and as a result, the concentration of CO ₂ -derived anions in the membrane electrode assembly can be reduced earlier. be able to. This means that the length of time during which a current greater than or equal to the predetermined current value A flows (that is, the fixed time T ₂ ) can be shortened, which contributes to further reduction of surplus power and improvement of output and power generation efficiency. .

As a means for making the volume of the catalyst layer (anode catalyst layer) of the first electrode 102 larger than the volume of the catalyst layer (cathode catalyst layer) of the second electrode 103, the area of the anode catalyst layer is made larger. The area of the surface of the anode catalyst layer on the side of the anion conductive electrolyte membrane 101 is made larger than the area of the surface of the cathode catalyst layer on the side of the anion conductive electrolyte membrane 101; the thickness of the anode catalyst layer is made larger than the thickness of the cathode catalyst layer; And combinations thereof. Increasing the area and thickness of the anode catalyst layer is advantageous from the viewpoint of improving the durability of the anode catalyst layer. FIG. 6 shows an example in which the area of the anode catalyst layer is larger than that of the cathode catalyst layer.

FIG. 7 is a schematic cross-sectional view showing still another example of an alkaline fuel cell that can be provided in the fuel cell unit 10a. FIG. 8 is a schematic top view showing the second separator 105 constituting the alkaline fuel cell 300 shown in FIG. 7, and shows the surface of the second separator 105 on the anion conductive electrolyte membrane 101 side. FIG. 9 is a schematic top view showing a state in which the second wall 113 is arranged on the surface of the second separator 105.

The alkaline fuel cell 300 shown in FIG. 7 has a heat medium flow path 120 for circulating the heat medium, and the other configuration is basically the alkaline fuel cell 100 of FIG. Can be similar.

The alkaline fuel cell 300 includes an anion conductive electrolyte membrane 101, a first electrode (anode electrode) 102 stacked on the first surface 101 b of the anion conductive electrolyte membrane 101, and a first surface of the anion conductive electrolyte membrane 101. A membrane electrode assembly composed of a second electrode (cathode electrode) 103 laminated on the second surface 101a facing to 101b; a first electrode laminated on the first electrode 102, comprising at least a fuel receiving portion 106 for receiving fuel; 1 separator 104; mainly comprising a second separator 105 stacked on the second electrode 103, which includes at least an oxidant receiving portion 107 for receiving an oxidant; and a heat medium flow path 120.

In the alkaline fuel cell having a heat medium flow path such as the alkaline fuel cell 300, the temperature controller 30a (temperature changing unit) heats (preferably further cools) the alkaline fuel cell using the heat medium. It is used when doing something. In this case, the temperature controller 30a (temperature changing unit) includes a device that supplies the temperature-controlled heat medium to the heat medium flow path 120 of the alkaline fuel cell.

Hereinafter, the alkaline fuel cell 300 will be described in more detail with reference to the drawings. The heat medium flow path 120 is configured so that the heat medium is brought into contact with only the anion conductive electrolyte membrane 101 in the membrane electrode assembly. Specifically, the first heat medium flow path 122 for contacting the heat medium only to the first electrode side surface (first surface 101b) of the anion conductive electrolyte membrane 101, and the anion conductive electrolyte membrane It consists of the 2nd heat-medium flow path 121 for making a heat medium contact only to the 2nd electrode side surface (2nd surface 101a) of 101 [refer FIG. 7].

As described above, according to the alkaline fuel cell 300 including the heat medium flow channel 120 configured so that the heat medium contacts and is supplied only to the anion conductive electrolyte membrane 101 in the membrane electrode assembly, the electrode Since the temperature of the anion conductive electrolyte membrane 101 positioned directly is directly adjusted by the heat medium, it is possible to improve the heat exchange efficiency (thus shortening the time required for the fuel cell to reach a desired temperature). And the accuracy of temperature adjustment of the electrode and the anion conductive electrolyte membrane 101 can be improved.

In addition, since the heat medium is not directly supplied to the electrodes of the membrane electrode assembly, the electrode pores are blocked as represented by flooding, and the power generation efficiency and output stability of the alkaline fuel cell are reduced. It is possible to prevent the decrease, and there is no possibility that the electrode is deteriorated by a small amount of impurities in the heat medium.

In the alkaline fuel cell 300, the first electrode 102 and the second electrode 103 have an area smaller than that of the anion conductive electrolyte membrane 101, the first separator 104, and the second separator 105, and accordingly, on the side of each electrode. Thus, there is a gap (space) where no electrode exists between the anion conductive electrolyte membrane 101 and each separator. The 1st electrode 102 and the 2nd electrode 103 are laminated | stacked on the approximate center part of the anion conductive electrolyte membrane 101 surface so that the position in the anion conductive electrolyte membrane 101 surface may correspond.

The first heat medium flow path 122 is a part of a gap (space) where the above-mentioned electrode interposed between the first separator 104 and the anion conductive electrolyte membrane 101 does not exist, and is separated from the two. The first space 110 is sandwiched between the first walls 112, and more specifically, the first space 110 and the first space 110 located immediately below the first space 110 and continuing to the first space 110. 1 recess 108. The first wall 112 is formed along both ends in the width direction of the first recess 108 (similar to FIG. 9), and the anion conductivity from the surface of the first separator 104 on the anion conductive electrolyte membrane 101 side in the thickness direction. It extends to the first surface 101b of the electrolyte membrane 101. That is, the first space 110 is an internal space formed by the first separator 104, the anion conductive electrolyte membrane 101, and the two first walls 112. Thereby, the leakage of the heat medium to the outside of the first space 110 is prevented.

The first space 110 is isolated (spatially separated) from other portions of the gap (space) where no electrode exists and the first electrode 102 and the fuel receiving portion 106 by the first wall 112 provided at the periphery thereof. It is in contact with only the first surface 101b of the anion conductive electrolyte membrane 101 in the membrane electrode assembly.

The first recess 108 is a recess provided on the anion conductive electrolyte membrane 101 side surface of the first separator 104 in a region where the first electrode 102 does not exist, and is independent of the third recess constituting the fuel receiving unit 106. And is formed so as to surround the fuel receiving portion 106 (similar to FIG. 8).

Similarly, the second heat medium flow path 121 is a part of a gap (space) where the above-described electrode interposed between the second separator 105 and the anion conductive electrolyte membrane 101 does not exist, and is spaced apart. The second space 111 is sandwiched between the two second walls 113. More specifically, the second space 111 is located immediately above the second space 111 and in the second space 111. The second recess 109 is continuous. The second wall 113 is formed along both widthwise ends of the second recess 109 [see FIG. 9], and the anion conductive electrolyte from the anion conductive electrolyte membrane 101 side surface of the second separator 105 in the thickness direction. The film 101 extends to the second surface 101a. That is, the second space 111 is an internal space formed by the second separator 105, the anion conductive electrolyte membrane 101 and the two second walls 113. Thereby, the leakage of the heat medium to the outside of the second space 111 is prevented.

The second space 111 is isolated (spatially separated) from the other part of the gap (space) where no electrode exists and the second electrode 103 and the oxidant receiving portion 107 by the second wall 113 provided at the periphery thereof. In the membrane electrode assembly, only the second surface 101a of the anion conductive electrolyte membrane 101 is in contact.

The second recess 109 is a recess provided on the surface of the second separator 105 on the anion conductive electrolyte membrane 101 side in a region where the second electrode 103 does not exist, and is independent of the fourth recess constituting the oxidant receiving unit 107. And it is formed so as to surround the oxidant receiving portion 107 (see FIG. 8).

In the alkaline fuel cell 300, the first separator 104 includes a third recess that constitutes the fuel receiving portion 106 and a first recess 108 that is a part of the first heat medium flow path 122 on the anion conductive electrolyte membrane 101 side. It can be a member having at least the surface. The second separator 105 is a member having at least a fourth concave portion constituting the oxidant receiving portion 107 and a second concave portion 109 which is a part of the second heat medium flow path 121 on the surface on the anion conductive electrolyte membrane 101 side. Can be. The third recess and the fourth recess are respectively provided on the surface of the first separator 104 and the second separator 105 on the anion conductive electrolyte membrane 101 side in the region where the first electrode 102 and the second electrode 103 are laminated.

The third recess and the fourth recess can be one or more flow channel grooves having a serpentine shape, a line shape, or other shapes as shown in FIG. It can be a recess formed so as to spread. A fuel supply pipe and a fuel discharge pipe may be connected to the inlet side end and the outlet side end of the third recess, respectively. Similarly, an oxidant supply pipe and an oxidant discharge pipe may be connected to the fourth recess at the inlet side end and the outlet side end, respectively.

As shown in FIG. 8 (exemplifying the second separator 105), the first recess 108 and the second recess 109 are respectively the fuel receiving portion 106 (third recess) and the oxidant receiving portion 107 (fourth). However, the present invention is not limited to this, and various shapes can be taken in consideration of heat exchange efficiency and the like. For example, the first recess 108 and the second recess 109 have a plurality of channel grooves, branched channel grooves, and a relatively large tank shape so that the heat medium can be brought into contact over a wider area of the electrolyte membrane surface. The surface of the first separator 104 and the second separator 105 may be all or almost the entire area excluding the fuel receiving portion 106 and the oxidant receiving portion 107, respectively. It may be formed.

Further, as shown in FIG. 10 (exemplifying the second separator 105), the first recess 108 and the second recess 109 are provided in order to obtain good heat exchange efficiency and temperature uniformity in the fuel cell. The first electrode 102 and the second electrode 103 are divided into a plurality of parts, and the fuel receiving part 106 and the oxidant receiving part 107 are also divided into a plurality of parts in accordance with this, and the divided fuel receiving part 106 and oxidant receiving part 107 are divided. By adopting a configuration such as disposing the first concave portion 108 and the second concave portion 109 between the first concave portion 108 and the second concave portion 109 over the largest possible area of the surface of the first separator 104 or the second separator 105, Further, it may be arranged as uniformly as possible in the plane. By adopting such a configuration, in addition to increasing the amount of heat exchange and improving the heat exchange efficiency, it is possible to improve the temperature uniformity in the separator surface, and thus the temperature uniformity in the alkaline fuel cell. it can.

Also in the alkaline fuel cell 300, a bipolar plate having both a fuel receiving portion and an oxidant receiving portion may be used as the first separator 104 and the second separator 105.

The first wall 112 and the second wall 113 respectively pass through the first space 110 and the second space 111 that are a part of the heat medium flow path, the other part of the gap (space) in which the above-described electrode does not exist, and the electrode And a wall that is isolated from the fuel / oxidant receiving portion, and extends from the surface of the separator on the anion conductive electrolyte membrane 101 side to the surface of the anion conductive electrolyte membrane 101 in the thickness direction.

The first wall 112 and the second wall 113 are formed so as to be substantially parallel to the first concave portion 108 and the second concave portion 109 and along both ends in the width direction of the concave portion [see FIG. 9]. The first wall 112 and the second wall 113 may be formed so as to cover all gaps (spaces) where no electrode exists, except for the first space 110 and the second space 111. In that case, an alkaline fuel cell is used. When the first separator and the second separator are fastened with a fastening member or the like, the stress is equalized and the stability is improved. Fastening between the first separator and the second separator can be performed using fastening members such as screws, bolts and nuts.

Further, a part of each of the first wall 112 and the second wall 113 is fitted into a groove formed so as to extend along both ends in the width direction of the recess substantially parallel to the first recess 108 and the second recess 109. You may arrange so that it may come in. According to such a configuration, the first wall 112 and the second wall 113 can be easily positioned when the alkaline fuel cell is assembled, and the productivity is improved. In addition, since the displacement of the first wall 112 and the second wall 113 can be prevented, a highly reliable alkaline fuel cell can be provided.

The material of the first wall 112 and the second wall 113 is not particularly limited as long as it is resistant to the heat medium and is impermeable to the heat medium. For example, butyl rubber, ethylene propylene rubber, chloroprene rubber, nitrile rubber , Elastic bodies such as silicon rubber, tetrafluoroethylene propylene rubber, tetrafluoroethylene perfluoromethylvinylidene rubber; thermoplastic resin represented by tetrafluoroethylene, polypropylene, polymethylpentene, metal represented by stainless steel, or An inelastic material such as an alloy can be used.

Especially, it is preferable that the 1st wall 112 and the 2nd wall 113 consist of elastic bodies. An elastic wall formed by applying pressure in the thickness direction of the fuel cell by using an elastic wall as an isolation wall interposed between each separator and the anion conductive electrolyte membrane 101 and forming a part of the heat medium flow path space By utilizing this deformation, the elastic wall, each separator, and the anion conductive electrolyte membrane 101 can be brought into good surface contact. Thereby, the sealing performance of these interfaces can be improved, and the leakage of the heat medium to the electrode and further to the fuel receiving portion 106 / oxidant receiving portion 107 can be more reliably prevented.

In addition, by using the elastic wall, in order to obtain a good sealing property at the interface between the elastic wall and the separator and the anion conductive electrolyte membrane 101, and a sufficient reduction effect of the contact resistance between the electrode and the separator, Even when a sufficient pressure is applied in the thickness direction of the fuel cell by fastening between the first separator and the second separator, the elastic wall is appropriately crushed by the pressure to generate a repulsive force. This can effectively prevent an increase in material diffusion resistance due to pore blockage.

As the heat medium, a known heat medium such as air, water vapor, chlorofluorocarbon, hydrochlorofluorocarbon, hydrofluorocarbon, etc .; water, aqueous solution, oil, liquid such as ethylene glycol can be used, but the heat capacity is high and efficient. It is preferable to use a liquid from the viewpoints of heat exchange and handling, and it is more preferable to use water or an aqueous solution.

In addition, when water or an aqueous solution is used as a heat medium, the anion conductive electrolyte membrane 101 can be directly humidified, and moisture can be supplied to the second electrode (cathode electrode) 103 via the anion conductive electrolyte membrane 101. Therefore, it is possible to omit a humidifier for humidifying the fuel and / or oxidant, which has been conventionally required, which is advantageous for miniaturization of the fuel cell system. Further, the humidification of the anion conductive electrolyte membrane 101 can improve the power generation efficiency and startability (the time required to obtain a desired output from the start of power generation).

The alkaline fuel cell 300 having the recesses (the first recess 108 and the second recess 109) formed on the separator surface as a part of the heat medium channel has been described as an alkaline fuel cell having the heat medium channel. However, the present invention is not limited to this, and the heat medium flow path may be formed inside the separator, or may be provided at a location different from the separator (the heat medium flow path is separately provided in the alkaline fuel cell). Attached etc.).

As the fuel supplied to the first electrode (anode electrode) of the alkaline fuel cell, for example, H ₂ gas, hydrocarbon gas, alcohol such as methanol, ammonia gas, or the like can be used, and among them, H ₂ gas is used. It is preferable. As the oxidant supplied to the second electrode (cathode electrode), for example, O ₂ gas or a gas containing O ₂ such as air can be used, and air is preferably used. The fuel and / or oxidant may be humidified.

As described above, when an alkaline fuel cell having a heat medium flow path, such as the alkaline fuel cell 300, is used as the fuel cell unit 10a, the temperature regulator 30a (temperature changing unit) An apparatus for supplying a medium to a heat medium flow path of an alkaline fuel cell; As such a temperature controller 30a, for example, a connection flow path (FIG. 7) that is connected to a heat medium flow path of an alkaline fuel cell and forms a circulation flow path for circulating the heat medium together with the heat medium flow path. The temperature of the heat medium is obtained by heat exchange between the connection flow path 130 in 10 to 10), the circulation device (circulation pump or the like) that circulates the heat medium in the circulation flow path, and the heat medium in the circulation flow path. And a device having a heat exchange device for adjustment. The heat exchange device is provided, for example, in a tank that contains a heat medium (second heat medium) different from the heat medium supplied to the heat medium flow path of the alkaline fuel cell, around the connection flow path, 2 It can be a jacket or the like for circulating a heat medium.

The control device and the fuel cell system of the present invention are not limited to the embodiment described above, and various modifications are possible. For example, in the above embodiment, when the temperature of the alkaline fuel cell is raised to a temperature equal to or higher than the predetermined temperature X, at least the temperatures of both the first electrode and the second electrode (for example, the entire alkaline fuel cell) are set to the predetermined temperature. However, the temperature controller 30a (temperature changing unit) can change the temperature of any one of the electrodes so that only one of the electrodes has a predetermined temperature X or more. The other temperature may be maintained at or near the previous temperature.

In the above case, it is particularly preferable that the electrode to be raised to a temperature equal to or higher than the predetermined temperature X is an anode, and the electrode maintained at or near the temperature just above is a cathode. Thus, OH ^- generates anion, OH ^- while suppressing the electrolyte in the catalyst layer is deteriorated by the cathode is an electrode tends to anion concentration becomes higher is placed under high temperature, from the anode electrode The amount of CO ₂ gas discharged per unit time can be increased, so that the concentration of CO ₂ -derived anions in the membrane electrode assembly can be reduced early.

As a means for changing only the temperature of either one of the electrodes, for example, a temperature changing unit (including a device for supplying a heat medium to the heat medium flow path by providing a heat medium flow path only to a separator laminated on the electrode) For example, use of a temperature changing unit (temperature controller) including a heating / cooling device or a heating device connected only to the electrodes, and the like.

Further, the detection unit 20 may detect any of the above [b] to [e] as “the state of the alkaline fuel cell”. In such a case, the same effect can be obtained. obtain.

In the case of detecting the concentration of the CO ₂ -derived anion (or CO ₃ ²⁻ concentration among these) in the anion conductive electrolyte membrane as “the state of the alkaline fuel cell”, the concentration is detected by the detection unit 20. When it is detected constantly or at regular intervals and it is determined that the concentration exceeds a predetermined concentration, the control unit 50 determines the temperature of the alkaline fuel cell regardless of whether the fuel cell unit 10 is generating power. And the temperature changing unit 30 is controlled so that the temperature becomes equal to or higher than the predetermined temperature X, and a current equal to or higher than the predetermined current value A is supplied to the membrane electrode assembly for a certain period of time under the temperature equal to or higher than the predetermined temperature X. The current value changing unit 40 is controlled to flow.

[C] When detecting the pH of the anion conductive electrolyte membrane as “the state of the alkaline fuel cell”, the pH is constantly or constant by the detection unit 20 (pH meter brought into contact with the anion conductive electrolyte membrane). If it is detected every hour and it is determined that the pH is lower than the predetermined pH, the control unit 50 performs the control as described above.

In the case of detecting the resistance value of [d] anion conductive electrolyte membrane as “the state of the alkaline fuel cell”, the resistance value is constantly or constant by the detection unit 20 by a method such as current interrupt measurement or impedance measurement. When it is detected every time and it is determined that the resistance value exceeds a predetermined resistance value, the control unit 50 performs the control as described above.

[E] When detecting the output voltage value of the alkaline fuel cell as “the state of the alkaline fuel cell”, the voltage value is constantly or constant by the detection unit 20 (voltmeter connected to the membrane electrode assembly). If it is determined that the obtained voltage / current characteristic is lower than the predetermined voltage / current characteristic (inferior to the predetermined voltage / current characteristic), the control unit 50 performs the control as described above. To do.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

[Production of control device and fuel cell system]
<Example 1>
In the following procedure, an alkaline fuel cell having the same configuration as that of FIG. 7 was produced, and a control device and a fuel cell system having the same configuration as that of FIG. 4 were produced using the alkaline fuel cell.

(1) Production of membrane electrode composite Anion-conducting solid polymer for catalyst layer by chloromethylating a copolymer of aromatic polyether sulfonic acid and aromatic polythioether sulfonic acid and then amination An electrolyte was obtained. By adding this to tetrahydrofuran, a 5 wt% anion conductive solid polymer electrolyte solution was obtained.

The catalyst-supported carbon particles (“TEC10E50E” manufactured by Tanaka Kikinzoku Co., Ltd.) having a Pt-supported amount of Pt / C of 50% by weight and the above-obtained electrolyte solution have a weight ratio of 2 / 0.2. A catalyst paste for the anode catalyst layer was prepared by mixing and further adding ion exchange water and ethanol.

Similarly, a catalyst-supporting carbon particle (“TEC10E50E” manufactured by Tanaka Kikinzoku Co., Ltd.) having a Pt support amount of 50% by weight and Pt / C and the electrolyte solution obtained above are 2 / 0.2 in weight ratio. The catalyst paste for the cathode catalyst layer was prepared by mixing the mixture as described above and further adding ion exchange water and ethanol.

Next, carbon paper (“TGP-H-060” manufactured by Toray Industries Inc., thickness of about 190 μm) is cut into an anode gas diffusion layer into a size of 22.3 mm long × 22.3 mm wide, and one side of the anode gas diffusion layer The catalyst paste for the anode catalyst layer was applied using a screen printing plate having a window of 22.3 mm in length and 22.3 mm in width so that the amount of catalyst was 0.5 mg / cm ^2. The anode electrode (first electrode) 102 in which the anode catalyst layer was formed on the entire surface of one side of the carbon paper, which was the anode gas diffusion layer, was produced. The thickness of the obtained anode 102 was about 200 μm.

Similarly, carbon paper (“TGP-H-060” manufactured by Toray Industries Inc., thickness of about 190 μm) is cut into a size of 22.3 mm long × 22.3 mm wide as a cathode gas diffusion layer, and one side of the cathode gas diffusion layer Then, the above-mentioned catalyst paste for the cathode catalyst layer was applied using a screen printing plate having a window of 22.3 mm in length and 22.3 mm in width so that the amount of catalyst was 0.5 mg / cm ^2. The cathode electrode (second electrode) 103 in which the cathode catalyst layer was formed on the entire surface of one side of the carbon paper that was the cathode gas diffusion layer was produced by drying with the above. The thickness of the obtained cathode electrode 103 was about 200 μm.

Next, a fluororesin polymer electrolyte (“Aciplex” manufactured by Asahi Kasei Co., Ltd.) cut into a size of 90 mm in length × 90 mm in width is used as the anion conductive electrolyte membrane 101, and the anode electrode 102, electrolyte membrane 101, and cathode electrode are used. 103 are stacked in this order so that the respective catalyst layers face the electrolyte membrane 101, and then subjected to thermocompression bonding at 130 ° C. and 10 kN for 2 minutes, whereby the anode electrode 102 and the cathode electrode 103 are connected to the electrolyte membrane 101. To obtain a membrane electrode composite. The superposition was performed so that the positions of the anode electrode 102 and the cathode electrode 103 in the plane of the electrolyte membrane 101 coincided, and the centers of the anode electrode 102, the electrolyte membrane 101, and the cathode electrode 103 coincided.

(2) Fabrication of alkaline fuel cell The outer shape is 90 mm long × 90 mm wide × 20 mm thick, and one surface has a channel groove as shown in FIG. 8 (the fuel receiving portion 106 and the first concave portion 108 in FIG. Alternatively, two members made of a carbon material in which the oxidant receiving portion 107 and the second concave portion 109) are formed are prepared as the first separator 104 and the second separator 105 having a current collecting function, respectively. The fuel receiving portion 106 included in the first separator 104 and the oxidant receiving portion 107 included in the second separator 105 are serpentine-shaped flow channel grooves as shown in FIG. 8 (flow channel width 800 μm, depth 800 μm). . The regions where the fuel receiving portion 106 and the oxidant receiving portion 107 are formed are the centers of the first separator 104 and the second separator 105, respectively, and the size is 22.3 mm long × 22.3 mm wide. The first recess 108 and the second recess 109 have a width of 800 μm and a depth of 800 μm, and are formed so as to surround the periphery of the fuel receiving portion 106 and the oxidant receiving portion 107, respectively. The first separator 104 is formed with a hole for inserting a temperature sensor (thermocouple) constituting the detection unit 20a.

As the first wall 112 and the second wall 113, two tetrafluoroethylene propylene rubber sheets (thickness 180 μm) as shown in FIG. 9 are used, and these are shown in FIG. 9 of the first separator 104 and the second separator 105, respectively. It was arranged at the position shown in

Next, the first space 110 between the first walls 112 and 112 is formed on the anode gas diffusion layer of the membrane electrode assembly obtained in (1) so that the groove forming surface faces the anode gas diffusion layer. The first separator 104 is laminated so as to be disposed immediately above the first recess 108 (so that the anode 102 is disposed immediately above the fuel receiving portion 106), and a groove forming surface is formed on the cathode gas diffusion layer. The cathode space 103 is disposed immediately below the oxidant receiving portion 107 so as to face the cathode gas diffusion layer and the second space 111 between the second walls 113 and 113 is disposed immediately below the second recess 109. The second separator 105 was laminated and these were fastened using bolts and nuts to obtain an alkaline fuel cell.

(3) Manufacture of Control Device and Fuel Cell System A control device having the same configuration as in FIG. 4 was manufactured, and a fuel cell system was manufactured using the alkaline fuel cell manufactured above as the fuel cell unit 10a. Specifically, it is as follows.

The fuel supply pipe is connected so that fuel can be supplied to the fuel receiving portion 106 of the first separator 104, and the oxidant supply pipe is connected so that oxidant can be supplied to the fuel receiving portion 107 of the second separator 105. . Further, a charge / discharge battery system ("PFX2011" manufactured by Kikusui Electric Co., Ltd., an ammeter, a voltmeter, and an electronic load device are integrally provided) as the detection unit 20a and the electronic load device 40a is provided in the fuel cell unit 10a. While connecting to the 1 separator 104 and the 2nd separator 105, the thermocouple as the detection part 20a was inserted in the hole for temperature sensor attachment of the 1st separator 104. This detection unit 20a detects the ratio T ₁ / T ₀ of the time T ₁ during which a current of a predetermined current value A or more flows between the anode electrode and the cathode electrode of the membrane electrode assembly within the unit time T ₀ . is there.

Further, as the temperature controller 30a, SUS pipes are connected to the inlet end and the outlet end of the heat medium flow path (the heat medium flow path of both the first separator 104 and the second separator 105) of the alkaline fuel cell. Then, a circulation channel for circulating the heat medium was constructed. A double plunger pump for circulating the heat medium was interposed in the circulation channel. A part of the SUS pipe was immersed in an oil bath capable of adjusting the temperature, and the temperature of the heat medium could be controlled.

Furthermore, a personal computer [time measuring means (timer) and storage means (memory) for storing current values and times T ₀ and T ₁ as the control unit 50a is provided. Is connected to the oil bath constituting the charge / discharge battery system, the thermocouple and the temperature controller 30a so that the detection result can be received, and the control information can be transmitted to the charge / discharge battery system based on the detection result.

[Evaluation of power generation efficiency of alkaline fuel cells]
(1) Placed in an environment of 50 ° C., unit time T ₀ = 14 minutes, time ratio W _T (= T ₁ / T ₀ ) = 10%, predetermined current value A = 600 mA / cm ² , predetermined current value A In the control device (fuel cell system) of Example 1 in which the time T ₂ for flowing the current was set to a predetermined temperature X = 55 ° C. (both anode side and cathode side) for 6 minutes, humidified H ₂ gas (relative Humidity 95%) is supplied to the fuel receiving portion 106 of the alkaline fuel cell at a flow rate of 200 mL / min, and humidified oxygen gas (relative humidity 95%) is supplied to the oxidant receiving portion 107 at a flow rate of 500 mL / min. While supplying, by stopping power generation of the fuel cell unit 10a (alkaline fuel cell) (current value 0 mA / cm ² ), current value 0 mA / cm ² (14 minutes, 50 ° C.) → current value 0 mA / cm ² (2 minutes, 50 ° C to 55 ° C Temperature rise) → current value 600 mA / cm ² (6 minutes, 55 ° C.) → current value 0 mA / cm ² (2 minutes, temperature drop from 55 ° C. to 50 ° C.) → current value 0 mA / cm ² (14 minutes, 50 ° C. ) → ... A current of 600 mA / cm ² was forcibly passed through the membrane electrode assembly in a temperature and current pattern.

The current extraction in such a pattern is based on the determination by the control unit 50a that the time ratio W _T = 0. After taking out the current in the pattern as described above for 2 hours and then taking out a current of 200 mA / cm ² , the time until a power generation efficiency of 50% was obtained was 4 minutes. The current value is a value obtained by dividing the amount of current flowing between the anode and cathode by the projected area of the cathode on the electrolyte membrane.

The power generation efficiency is based on the actual voltage value (output voltage value) measured by the voltmeter included in the charge / discharge battery system, and the following formula:
Power generation efficiency = actual voltage value / 1.23
Calculated by

(2) Next, the setting is changed to a predetermined current value A = 700 mA / cm ² , and humidified H ₂ gas (relative humidity 95%) is supplied to the fuel receiving portion 106 of the alkaline fuel cell at a flow rate of 200 mL / min. While supplying the humidified oxygen gas (relative humidity 95%) to the oxidant receiving unit 107 at a flow rate of 500 mL / min, power generation in the fuel cell unit 10a (alkaline fuel cell) is stopped (current value 0 mA). by / cm ²⁾ to keep the current value 0mA / cm ² (14 min, 50 ° C.) → current 0mA / cm ^{2 (2} min, heating from 50 ° C. to 55 ° C.) → current value 700 mA / cm ² (6 minutes, 55 ° C.) → current value 0 mA / cm ² (2 minutes, temperature drop from 55 ° C. to 50 ° C.) → current value 0 mA / cm ² (14 minutes, 50 ° C.) → ... Temperature and current value pattern In the membrane electrode assembly intermittently A current of 700 mA / cm ² was forced to flow.

After taking out the current with the above pattern for 2 hours and taking out a current of 200 mA / cm ² , it took 3 minutes to obtain a power generation efficiency of 50%.

<Example 2>
Instead of the second separator 105 having the second recess 109, a separator not having the recess was used, and an alkaline fuel cell was produced in the same manner as in Example 1 except that the installation of the second wall 113 was omitted. Using this, a fuel cell system was produced in the same manner as in Example 1.

When the power generation efficiency was evaluated in the same manner as in (1) of Example 1 above (however, only the anode side is heated to 55 ° C.), the time until 50% power generation efficiency is obtained is It was 4 minutes.

<Comparative Example 1>
A fuel cell system was produced in the same manner as in Example 1 except that the temperature controller 30a was not provided.

Placed in an environment of 50 ° C., unit time T ₀ = 14 minutes, time ratio W _T (= T ₁ / T ₀ ) = 10%, predetermined current value A = 500 mA / cm ² , current of predetermined current value A In the control device (fuel cell system) of Comparative Example 1 in which the flow time T ₂ is set to 6 minutes, humidified H ₂ gas (relative humidity 95%) is supplied to the fuel receiving unit 106 of the alkaline fuel cell at 200 mL / min. While supplying at a flow rate, while supplying humidified oxygen gas (relative humidity 95%) to the oxidant receiving unit 107 at a flow rate of 500 mL / min, power generation of the fuel cell unit 10a (alkaline fuel cell) is stopped (current) Value 0 mA / cm ² ), current value 0 mA / cm ² (14 minutes, 50 ° C.) → current value 500 mA / cm ² (6 minutes, 50 ° C.) → current value 0 mA / cm ² (14 minutes, 50 ° C) → ... temperature and A current of 500 mA / cm ² was forcibly passed through the membrane electrode assembly in a current value pattern.

After taking out the current in the above pattern for 2 hours and then taking out a current of 200 mA / cm ² , the time required to obtain 50% power generation efficiency was 8 minutes.

10, 10a Fuel cell part, 20, 20a detection part, 30 temperature change part, 30a temperature regulator, 40 current value change part, 40a electronic load device, 50, 50a control part, 60 electronic device, 100, 200, 300 alkali Fuel cell, 101 anion conductive electrolyte membrane, 101a second surface, 101b first surface, 102 first electrode, 103 second electrode, 104 first separator, 105 second separator, 106 fuel receiving part, 107 oxidant receiving , 108, first recess, 109, second recess, 110, first space, 111, second space, 112, first wall, 113, second wall, 120, heat medium flow path, 121, second heat medium flow path, 122, first heat Medium flow path, 130 connection flow path, 150 gasket.

Claims (10)

1. A detection unit for detecting a state of an alkaline fuel cell including a membrane electrode assembly including an anion conductive electrolyte membrane;
   A temperature changing unit for changing the temperature of the alkaline fuel cell;
   A current value changing unit for changing a current value flowing through the membrane electrode assembly of the alkaline fuel cell;
   Connected to the detection unit, the temperature change unit, and the current value change unit, and according to the detection result by the detection unit, the temperature of the alkaline fuel cell is increased so that the temperature becomes a predetermined temperature X or more. And a control for controlling the current value changing unit so that a current of a predetermined current value A or more flows through the membrane electrode assembly for a predetermined time under a temperature of the predetermined temperature X or higher. And
   A control device comprising:
2. The detection unit at least includes the temperature of the alkaline fuel cell and a ratio T ₁ / T _{0 of} a time T ₁ during which a current of a predetermined current value A or more flows through the membrane electrode assembly within a unit time T ₀ . The control device according to claim 1, which is to be detected.
3. The control device according to claim 1, wherein the temperature changing unit includes a heating / cooling device capable of heating and cooling the alkaline fuel cell or a heating device for heating the alkaline fuel cell.
4. The control device according to claim 3, wherein the temperature changing unit includes a device for supplying the heat medium to a flow path for circulating the heat medium, which is included in the alkaline fuel cell.
5. The control device according to claim 1, wherein the current value changing unit includes an electronic load device or a variable resistor connected to the alkaline fuel cell.
6. The membrane electrode assembly includes the anion conductive electrolyte membrane, a first electrode laminated on a first surface of the anion conductive electrolyte membrane, and a second electrode facing the first surface of the anion conductive electrolyte membrane. A second electrode laminated on the surface,
   The control device according to claim 1, wherein the temperature changing unit changes a temperature of the first electrode.
7. The control device according to claim 6, wherein the first electrode is an anode electrode and the second electrode is a cathode electrode.
8. The control device according to claim 1, wherein the predetermined temperature X is 105% to 150% of the temperature of the alkaline fuel cell immediately before the temperature is raised by the temperature changing unit.
9. The control device according to claim 1, wherein the predetermined current value A is in a range of 600 to 1000 mA / cm ² .
10. A fuel cell system comprising a fuel cell unit including the alkaline fuel cell and the control device according to claim 1.

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