JP2015141819A - Pretreatment method of fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pretreatment method of a fuel cell capable of obtaining a fuel cell excellent in power generation performance in a short time.SOLUTION: Prior to steady operation for generating power steadily from a fuel cell 1 including an electrolyte layer 4, an anode electrode 2 supplied with fuel and a cathode electrode 3 supplied with oxygen, arranged oppositely while sandwiching the electrolyte layer 4, pretreatment power generation is performed so as to increase the ratio of liquid fuel, supplied to the anode electrode 2 side and leaking to the cathode electrode 3 side, compared with that during steady operation, thus performing pretreatment of the fuel cell 1.

Description

  The present invention relates to a fuel cell pretreatment method.

  Conventionally, various fuel cells such as alkaline type (AFC), solid polymer type (PEFC), phosphoric acid type (PAFC), molten carbonate type (MCFC), solid electrolyte type (SOFC) are known as fuel cells. Yes. These fuel cells are being studied for use in various applications such as automobile applications.

  For example, a polymer electrolyte fuel cell includes a fuel-side electrode (anode catalyst layer) to which fuel is supplied and an oxygen-side electrode (cathode catalyst layer) to which oxygen is supplied. Oppositely arranged with an electrolyte layer made of a polymer membrane in between.

  As such a polymer electrolyte fuel cell, specifically, for example, a fuel cell including an electrolyte membrane, and a fuel electrode and an oxygen electrode arranged to face each other with the electrolyte membrane interposed therebetween is known. A fuel cell, a fuel supply means for supplying hydrazines as fuel to the fuel electrode, an oxygen supply means for supplying oxygen to the oxygen electrode, and an exhaust containing hydrazines discharged from the oxygen electrode side And a detoxifying means for supplying oxygen supplied from the oxygen supply means to the storing part and detoxifying the waste accumulated in the storing part have been proposed (for example, (See Patent Document 1).

  In such a fuel cell system, fuel is supplied to the fuel electrode and oxygen is supplied to the oxygen electrode, so that the fuel cell system is operated in a steady state.

  Further, such a power generation battery system is generally operated in the same manner as the steady operation as a pretreatment before the steady operation (before shipment), and the power generation efficiency is improved.

JP 2009-224219 A

  On the other hand, such a fuel cell is required to further improve the power generation performance and shorten the pretreatment time.

  Accordingly, an object of the present invention is to provide a fuel cell pretreatment method capable of obtaining a fuel cell excellent in power generation performance in a short time.

  In order to achieve the above object, a pretreatment method for a fuel cell according to the present invention includes an electrolyte layer, an anode electrode disposed opposite to the electrolyte layer, and supplied with liquid fuel, and a cathode supplied with oxygen. A pretreatment method for a fuel cell comprising an electrode, comprising: a pretreatment operation step for pretreatment power generation of the fuel cell before a steady operation for generating power constantly in the fuel cell, wherein the pretreatment operation step includes: The ratio of leakage of the liquid fuel supplied to the anode electrode side with respect to the cathode electrode side is increased more than that during the steady operation.

  In the pretreatment method for a fuel cell according to the present invention, it is preferable that the concentration of the liquid fuel during the pretreatment operation is increased more than that during the steady operation.

  In the fuel cell pretreatment method of the present invention, it is preferable that the pressure applied to the anode electrode is higher than the pressure applied to the cathode electrode during the pretreatment operation.

  In the fuel cell pretreatment method of the present invention, in the pretreatment operation step, the ratio of liquid fuel supplied to the anode electrode side to the cathode electrode side (cross leak) is determined from the ratio of cross leak during steady operation. Therefore, the cathode electrode is activated by the liquid fuel that has been cross-leaked during the pretreatment operation.

  As a result, according to such a pretreatment method for a fuel cell, a fuel cell excellent in power generation performance can be obtained in a shorter time.

FIG. 1 is a schematic configuration diagram showing a fuel cell used in one embodiment of a fuel cell pretreatment method of the present invention. FIG. 2 is a graph showing the power generation performance of the fuel cells of Example 1 and Comparative Example 1.

FIG. 3 is a graph showing the power generation performance of the fuel cells of Example 2 and Comparative Example 2.

1. 1. Overall Configuration of Fuel Cell In FIG. 1, a fuel cell 1 is a polymer electrolyte fuel cell and includes a plurality of fuel cells S, and a stack structure in which these fuel cells S are stacked (cell stack) It is formed as a body 15 (described later).

  In FIG. 1, one fuel cell S is taken out for easy illustration.

  The fuel battery cell S includes an electrolyte layer 4, an anode electrode 2 that is disposed to face the electrolyte layer 4 and that is supplied with fuel (described later), and a cathode electrode 3 that is supplied with oxygen.

  The electrolyte layer 4 is, for example, a layer in which an anion component can move, and is specifically formed using an anion exchange membrane.

The anion exchange membrane is not particularly limited as long as it is a medium in which an anion component (for example, hydroxide ion (OH ⁻ )) can move, and for example, an anion exchange group such as a quaternary ammonium group or a pyridinium group can be used. And a solid polymer membrane (anion exchange resin).

  Examples of the solid polymer forming the anion exchange membrane include hydrocarbon-based solid polymer membranes such as polystyrene and modified products thereof.

  The solid polymer forming the anion exchange membrane may have a cross-linked structure in its molecular structure.

  Such an anion exchange membrane is not particularly limited, and can be obtained by, for example, the method described in JP 2010-165459 A.

  Moreover, an anion exchange membrane is available as a commercial item, for example, Selemion (made by Asahi Glass Co., Ltd.), Neoceptor (made by Astom Corp.), etc. are mentioned.

  Moreover, the film thickness of the electrolyte layer 4 is 10-100 micrometers, for example.

  The anode electrode 2 is formed of, for example, an electrode material such as a catalyst carrier that supports a catalyst. Alternatively, a catalyst may be used as an electrode material without using a catalyst carrier, and the catalyst may be directly formed as the anode electrode 2.

  The catalyst is not particularly limited, and examples thereof include platinum group elements (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt)), iron group elements ( According to a periodic table such as iron (Fe), cobalt (Co), nickel (Ni)) (IUPAC Periodic Table of the Elements (version date 22 June 2007), the same applies hereinafter) Group 8 to 10 (VIII) elements, For example, periodic table 11th group (IB) elements, such as copper (Cu), silver (Ag), and gold (Au), and simple metals such as zinc (Zn), and alloys thereof may be used.

  These can be used alone or in combination of two or more.

  Examples of the catalyst carrier include porous substances such as carbon.

  The amount of the catalyst supported on the catalyst carrier is not particularly limited, and is appropriately set according to the purpose and application.

  The thickness of the anode electrode 2 is, for example, 10 to 200 μm, preferably 20 to 100 μm.

  The cathode electrode 3 is formed of, for example, an electrode material such as a catalyst carrier carrying a catalyst, similarly to the anode electrode 2 described above. Alternatively, a catalyst may be used as the electrode material without using the catalyst carrier, and the catalyst may be formed directly as the cathode electrode 3.

  In the cathode electrode 3, as an electrode material, for example, a complex formed of a complex-forming organic compound and / or a conductive polymer and carbon (hereinafter, this complex is referred to as “carbon composite”), and a transition metal is used. A supported catalyst can also be used.

  Examples of the transition metal include scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu ), Yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), lanthanum (La) ), Hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), and the like. Among these, Preferably, silver and cobalt are mentioned. These may be used alone or in combination of two or more.

  The complex-forming organic compound is an organic compound that forms a complex with the metal atom by coordinating with the metal atom. For example, pyrrole, porphyrin, tetramethoxyphenylporphyrin, dibenzotetraazaannulene, phthalocyanine, choline, chlorin , A complex-forming organic compound such as phenanthroline or sarcomine, or a polymer thereof. Of these, polypyrrole, phenanthroline, and sarcomin, which are pyrrole polymers, are preferable. These may be used alone or in combination of two or more.

  As the conductive polymer, there is a compound overlapping with the above complex-forming organic compound, for example, polyaniline, polypyrrole, polythiophene, polyacetylene, polyvinylcarbazole, polytriphenylamine, polypyridine, polypyrimidine, polyquinoxaline, polyphenylquinoxaline, Examples include polyisothianaphthene, polypyridinediyl, polythienylene, polyparaphenylene, polyflurane, polyacene, polyfuran, polyazulene, polyindole, and polydiaminoanthraquinone. Among these, Preferably, a polypyrrole is mentioned. These may be used alone or in combination of two or more.

  The thickness of the cathode electrode 3 is, for example, 10 to 300 μm, preferably 20 to 150 μm.

  The fuel cell S further includes a fuel supply member 5 and an oxygen supply member 6.

  The fuel supply member 5 is made of a gas-impermeable conductive member, and one surface thereof is opposed to the surface of the anode electrode 2 opposite to the surface in contact with the electrolyte layer 4. The fuel supply member 5 is formed with a fuel-side flow path 7 for bringing fuel into contact with the entire anode electrode 2 as a distorted groove recessed from one surface. The fuel-side flow path 7 is formed with a fuel supply port 8 and a fuel discharge port 9 that pass through the fuel supply member 5 continuously at the upstream end and the downstream end, respectively. Specifically, a fuel supply port 8 is formed at the upstream end (lower side in FIG. 1), and a fuel discharge port 9 is formed at the downstream end (upper side in FIG. 1).

  Similarly to the fuel supply member 5, the oxygen supply member 6 is made of a gas-impermeable conductive member, and one surface of the oxygen supply member 6 is opposite to the surface in contact with the electrolyte layer 4 in the cathode electrode 3. Is opposed to the surface. The oxygen supply member 6 also has an oxygen-side flow channel 10 for contacting oxygen (air) with the entire cathode electrode 3 as a distorted groove recessed from one surface. The oxygen-side flow path 10 also has an oxygen supply port 11 and an oxygen discharge port 12 that pass through the oxygen supply member 6 continuously formed at the upstream end portion and the downstream end portion thereof. Specifically, an oxygen supply port 11 is formed at the upstream end (upper side of the paper in FIG. 1), and an oxygen discharge port 12 is formed at the downstream end (lower side of the paper in FIG. 1).

  The fuel cell 1 is formed as a stack structure in which a plurality of fuel cells S are stacked as described above. Therefore, although not shown, the fuel supply member 5 and the oxygen supply member 6 are configured (also used) as separators in which the fuel side flow path 7 and the oxygen side flow path 10 are formed on both surfaces.

  Although not shown in FIG. 1, the fuel cell 1 is provided with a current collector plate formed of a conductive material, and the electromotive force generated in the fuel cell 1 is provided in the current collector plate. It is taken out from the terminal.

  Further, on a test (model) basis, the fuel supply member 5 and the oxygen supply member 6 are connected by an external circuit 13, and a voltmeter 14 is interposed in the external circuit 13, thereby generating the fuel cell 1. The voltage can also be measured.

  Although not shown, in the cell laminate 15, a known gas diffusion layer or the like can be laminated together with the fuel supply member 5 and the oxygen supply member 6 as necessary. Etc. can also be provided.

  In addition, such a fuel cell 1 includes a pair of covers C at both ends in the stacking direction of the cell stack 15.

  The pair of covers C are formed in a substantially rectangular flat plate shape having the same size as the fuel supply member 5 and the oxygen supply member 6 that are also used as separators. Further, the cover C on one side in the stacking direction (hereinafter referred to as the front side) is provided with a fuel supply unit 16, a fuel discharge unit 17, an oxygen supply unit 18, and an oxygen discharge unit 19.

  In order to supply fuel to the fuel-side flow path 7 of the fuel cell S, the fuel supply unit 16 has one end in the left-right direction (hereinafter, right side) and one end in the vertical direction (hereinafter, lower side) of the front cover C. It is arranged in the part. The fuel supply unit 16 is formed in a substantially cylindrical shape so as to penetrate the front cover C in the stacking direction.

  In order to discharge fuel from the fuel-side flow path 7 of the fuel cell S, the fuel discharge portion 17 is the other end in the left-right direction (hereinafter referred to as the left side) and the other side in the vertical direction (hereinafter referred to as the upper side) of the front cover C. Is arranged. The fuel discharge portion 17 is formed in a substantially cylindrical shape so as to penetrate the front cover C in the stacking direction.

  The oxygen supply unit 18 is disposed at the upper right end of the front cover C in order to supply oxygen to the oxygen side flow path 10 of the fuel cell S. The oxygen supply unit 18 is formed in a substantially cylindrical shape so as to penetrate the front cover C in the stacking direction.

  The oxygen discharge unit 19 is disposed at the lower left end of the front cover C in order to discharge oxygen from the oxygen side flow path 10 of the fuel cell S. The oxygen discharge part 19 is formed in a substantially cylindrical shape so as to penetrate the front cover C in the stacking direction.

Further, in such a fuel cell 1, a cooling medium flow path (not shown) for cooling each fuel cell S is provided in the fuel supply member 5 and / or the oxygen supply member 6 as necessary. it can. Further, in such a case, the cooling medium is discharged from the cooling medium supply section for supplying the cooling medium to the cooling medium flow path and the cooling medium flow path at the center in the left-right direction of the front cover C. A cooling medium discharge part (see broken line).
2. Steady Operation of Fuel Cell The fuel cell 1 generates electric power when air (oxygen) is supplied to the cathode electrode 3 and liquid fuel is supplied to the anode electrode 2. More specifically, in the fuel cell 1, air is supplied from the oxygen supply unit 18 to the oxygen side channel 10, and liquid fuel containing a fuel compound is supplied from the fuel supply unit 16 to the fuel side channel 7. Therefore, power is generated constantly (steady operation).

In this fuel cell 1, examples of the liquid fuel supplied to the fuel side flow path 7 include a liquid fuel containing hydrazines as a fuel compound. Examples of the liquid fuel include methanol, dimethyl ether, hydrazines ( For example, anhydrous hydrazine _(NH 2 NH 2), hydrazine hydrate _{(NH 2 NH 2 · H 2} O), triazane _{(NH 2} NHNH 2), such as Tetorazan _{(NH 2} NHNHNH 2)) and the like.

  In addition, in the case of liquid fuel, the above-mentioned fuel compound is usually dissolved in water and / or an organic solvent (for example, lower alcohols such as methanol, ethanol, propanol, and isopropanol when hydrazines are used as the fuel compound). As a solution, it is supplied.

  In such a case, the concentration of the liquid fuel (that is, the concentration of the fuel compound in the liquid fuel (solution)) varies depending on the type of the fuel compound, but is, for example, 5% by mass or more, preferably 10% during steady operation. For example, it is 20% by mass or less, and preferably 15% by mass or less.

  Further, for example, alkali metal hydroxides such as potassium hydroxide and sodium hydroxide can be added to the liquid fuel as additives. The addition amount of the additive is not particularly limited, and is appropriately set according to the purpose and application.

The power generation in the fuel cell 1 will be described more specifically. While supplying oxygen (air) to the oxygen side channel 10 of the oxygen supply member 6, the fuel described above is supplied to the fuel side channel 7 of the fuel supply member 5. In the cathode electrode 3, electrons (e ⁻ ), water (H ₂ O), oxygen (O ₂ ), which are generated in the anode electrode 2 and move through the external circuit 13, as described below. ₂ ) reacts to produce hydroxide ions (OH ⁻ ). The generated hydroxide ions (OH ⁻ ) move from the cathode electrode 3 to the anode electrode 2 through the electrolyte layer 4 made of an anion exchange membrane. In the anode electrode 2, hydroxide ions (OH ⁻ ) that have passed through the electrolyte layer 4 react with the fuel to generate electrons (e ⁻ ). The generated electrons (e ⁻ ) are moved from the fuel supply member 5 to the oxygen supply member 6 via the external circuit 13 and supplied to the cathode electrode 3. An electromotive force is generated by such an electrochemical reaction at the anode electrode 2 and the cathode electrode 3, and power generation is performed.

For example, when methanol (CH ₃ OH) is used as the fuel, the above reaction can be expressed by the following reaction formulas (1) to (3) as the anode electrode 2 and the cathode electrode 3 as a whole.
(1) CH ₃ OH + 6OH ⁻ → CO ₂ + 5H ₂ O + 6e ⁻ (fuel side electrode)
(2) O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻ (oxygen side electrode)
(3) CH ₃ OH + 3 / 2O ₂ → CO ₂ + 2H ₂ O (whole)
For example, when hydrazine (NH ₂ NH ₂ ) is used as the fuel, the above reaction can be expressed by the following reaction formulas (4) to (6) as the anode electrode 2 and the cathode electrode 3 as a whole. it can.
(4) NH ₂ NH ₂ + 4OH ⁻ → 4H ₂ O + N ₂ + 4e ⁻ (fuel side electrode)
(5) O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻ (oxygen side electrode)
(6) NH ₂ NH ₂ + O ₂ → 2H ₂ O + N ₂ (whole)
When such electrochemical reaction occurs continuously, the reaction represented by the above formula (3) or (6) occurs in the fuel cell 1 as a whole, and an electromotive force is generated in the fuel cell 1.

  Further, during such steady operation, the pressure applied to the anode electrode 2 is set to be lower than the pressure applied to the cathode electrode 3.

  More specifically, in such a fuel cell 1, since the liquid fuel is pressure-transported at a predetermined flow rate, when the liquid fuel is supplied to the anode electrode 2, pressure is applied to the anode electrode 2. Is done.

  During steady operation, the flow rate of the liquid fuel with respect to the anode electrode 2 is, for example, 0.05 L / min / cell or more, preferably 0.1 L / min / cell or more as the flow rate per fuel cell S, For example, it is 0.5 L / min / cell or less, preferably 0.4 L / min / cell or less.

  Moreover, the back pressure in the transport of the liquid fuel is, for example, 1 kPa or more, preferably 2 kPa or more, for example, 15 kPa or less, preferably 10 kPa or less.

  In such a case, the pressure applied to the anode electrode 2 is, for example, 1 kPa or more, preferably 5 kPa or more, for example, 15 kPa or less, preferably 10 kPa or less.

  The flow rate of the liquid fuel and the pressure on the anode electrode 2 can be adjusted by, for example, providing a known throttle valve (not shown) in the fuel supply unit 16 and / or the fuel discharge unit 17 and adjusting the opening thereof. Can be set.

  Further, in such a fuel cell 1, since air is pressure-transported at a predetermined flow rate, when air is supplied to the cathode electrode 3, pressure is applied to the cathode electrode 3.

  During steady operation, the flow rate of air to the cathode electrode 3 is, for example, 2.0 L / min / cell or more, preferably 5.0 L / min / cell or more, as the flow rate per fuel cell S, for example, 20 L / min / cell or less, preferably 10 L / min / cell or less.

  Further, the back pressure in such air transportation is, for example, 5 kPa or more, preferably 10 kPa or more, for example, 60 kPa or less, preferably 20 kPa or less.

  In such a case, the pressure with respect to the cathode electrode 3 is larger than the pressure with respect to the anode electrode 2, and is, for example, 10 kPa or more, preferably 15 kPa or more, for example, 60 kPa or less, preferably 20 kPa or less.

  The flow rate of air and the pressure on the cathode electrode 3 are set by, for example, providing a known throttle valve (not shown) in the oxygen supply unit 18 and / or the oxygen discharge unit 19 and adjusting the opening thereof. can do.

  In a steady operation, the difference between the pressure on the anode electrode 2 and the pressure on the cathode electrode 3 is, for example, 4 kPa or more, preferably 10 kPa or more, for example, 45 kPa or less, preferably 20 kPa or less.

Moreover, the operating temperature of the fuel cell 1 is not particularly limited. For example, the temperature of the fuel cell S is set to 30 to 100 ° C., preferably 60 to 90 ° C.
3. Pretreatment of the fuel cell The fuel cell 1 described above is activated (pretreated) before being subjected to the steady operation as described above, thereby improving the power generation efficiency. Hereinafter, the fuel cell pretreatment method will be described in detail.

  In this method, before the above-described steady operation (for example, before shipment), the fuel cell 1 is subjected to pre-processing power generation (pre-processing operation step).

  In the pretreatment operation step, air is supplied from the oxygen supply unit 18 to the oxygen side channel 10 and liquid fuel containing a fuel compound is supplied from the fuel supply unit 16 to the fuel side channel 7 in the same manner as in the above-described steady operation. The fuel cell 1 is supplied to generate electricity.

  In this method, in the pretreatment operation step, the liquid fuel supplied to the anode electrode 2 side leaks (hereinafter referred to as a cross leak) to the cathode electrode side (hereinafter referred to as the liquid fuel cross leak ratio). The power is generated so as to increase more than that in the steady operation described above.

  The method for increasing the cross leak ratio of the liquid fuel is not particularly limited. For example, a method of increasing the concentration of the liquid fuel during the pretreatment operation as compared with the concentration of the liquid fuel during the steady operation may be mentioned.

  That is, in this method, liquid fuel having a higher concentration than that used during steady operation is used during pretreatment operation.

  The concentration of the liquid fuel during the pretreatment operation (that is, the concentration of the fuel compound in the liquid fuel (solution)) is, for example, 15% by mass or more, preferably 20% by mass or more, for example, 40% by mass or less, Preferably, it is 30 mass% or less.

  The increase rate of the liquid fuel concentration during the pretreatment operation is, for example, 50% or more, preferably 100% or more, and usually 200% or less with respect to the liquid fuel concentration during the steady operation. .

  In this way, the concentration gradient between the anode electrode 2 side and the cathode electrode 3 side is increased by increasing the concentration of the liquid fuel at the time of the pretreatment operation compared to the concentration of the liquid fuel at the time of the steady operation. Liquid fuel is liable to cross leak.

  As a result, the rate at which the liquid fuel cross-leaks during the pretreatment operation can be increased more than the rate at which the liquid fuel cross-leaks during the steady operation.

  Further, as a method for increasing the cross leak ratio of the liquid fuel, in addition to the above-described method, for example, a method in which the pressure on the anode electrode 2 is made higher than the pressure on the cathode electrode 3 during the pretreatment operation.

  Specifically, in this method, for example, a known throttle valve (not shown) is provided in the fuel supply unit 16 and / or the fuel discharge unit 17, and the flow rate of the liquid fuel is adjusted by adjusting the opening degree. In addition, the pressure on the anode electrode 2 is adjusted.

  During the pretreatment operation, the flow rate of the liquid fuel with respect to the anode electrode 2 is, for example, 0.05 L / min / cell or more, preferably 0.1 L / min / cell or more as the flow rate per fuel cell S. For example, it is 0.5 L / min / cell or less, preferably 0.4 L / min / cell or less.

  Moreover, the back pressure in the transport of the liquid fuel is, for example, 10 kPa or more, preferably 20 kPa or more, for example, 60 kPa or less, preferably 40 kPa or less.

  During such pretreatment operation, the pressure applied to the anode electrode 2 is, for example, 10 kPa or more, preferably 20 kPa or more, for example, 60 kPa or less, preferably 40 kPa or less.

  Further, in this method, for example, a known throttle valve (not shown) is provided in the oxygen supply unit 18 and / or the oxygen discharge unit 19, and the opening is adjusted to adjust the flow rate of air and the cathode. The pressure on the electrode 3 is adjusted.

  During the pretreatment operation, the air flow rate with respect to the cathode electrode 3 is, for example, 2 L / min / cell or more, preferably 5 L / min / cell or more, for example, 20 L / min. Min / cell or less, preferably 10 L / min / cell or less.

  The back pressure in air transportation is, for example, 1 kPa or more, preferably 2 kPa or more, for example, 10 kPa or less, preferably 5 kPa or less.

  During such pretreatment operation, the pressure on the cathode electrode 3 is smaller than the pressure on the anode electrode 2, for example, 1 kPa or more, preferably 5 kPa or more, for example, 20 kPa or less, preferably 10 kPa or less. .

  During the pretreatment operation, the difference between the pressure on the anode electrode 2 and the pressure on the cathode electrode 3 is, for example, 10 kPa or more, preferably 15 kPa or more, for example, 60 kPa or less, preferably 40 kPa or less. .

  Thus, by making the pressure on the anode electrode 2 higher than the pressure on the cathode electrode 3 during the pretreatment operation, the liquid fuel easily cross-leaks according to the pressure.

  As a result, the rate at which the liquid fuel cross-leaks during the pretreatment operation can be increased more than the rate at which the liquid fuel cross-leaks during the steady operation.

  Preferably, the two methods described above are used in combination during the pretreatment operation. That is, during the pretreatment operation, the liquid fuel concentration during the pretreatment operation is increased more than the liquid fuel concentration during the steady operation, and the pressure applied to the anode electrode 2 is set higher than the pressure applied to the cathode electrode 3.

  Thereby, the rate at which the liquid fuel cross-leaks during the pretreatment operation can be increased particularly efficiently than the rate at which the liquid fuel cross-leaks during the steady operation.

  In this fuel cell 1 pretreatment method, the fuel cell 1 is subjected to pretreatment power generation for a predetermined time (for example, 10 to 30 hours) under the above-described conditions, and the pretreatment operation is performed. Cross leak to the cathode electrode 3 side.

  When the liquid fuel cross leaks from the anode electrode 2 side to the cathode electrode 3 side, the cathode side electrode 3 is wet-treated. Further, depending on the type of fuel compound in the liquid fuel and the type of additive (for example, alkali metal hydroxide), the cathode side electrode 3 is subjected to alkali treatment.

  As described above, the cathode electrode 3 can be activated by performing the pretreatment operation before the steady operation and treating the cathode electrode 3 (wetting treatment, alkali treatment, etc.). Improvements can be made.

  Then, as necessary, the cross-leaked liquid fuel is discharged from the oxygen-side channel 10 from the fuel cell 1 pretreated as described above, and then air is supplied to the oxygen-side channel 10. By supplying a liquid fuel containing a fuel compound to the fuel side channel 7, power generation (steady operation) can be performed.

Although not described in detail, if necessary, before the above-described pretreatment power generation step, for example, water or the like is supplied to the fuel supply passage 7 or the oxygen supply passage 10 to wet-treat the anode electrode 2 and the cathode electrode 3. You can also
4). Effects The fuel cell 1 pretreated by the above pretreatment method has excellent power generation performance.

  That is, since the cross leak of the liquid fuel in the fuel cell 1 is not originally desirable, the power generation conditions during the steady operation are conditions that can suppress the cross leak.

  In the conventional fuel cell pretreatment method, the power generation conditions are the same as those in the steady operation even when the pretreatment power generation is performed before the steady operation. Therefore, in the conventional pretreatment method, the cross leak of the liquid fuel is suppressed, and the activation of the cathode electrode 3 is insufficient.

  On the other hand, in the pretreatment method of the fuel cell 1 described above, in the pretreatment operation step, the ratio of the liquid fuel supplied to the anode electrode 2 side leaking (cross leak) to the cathode electrode 3 side is crossed during the steady operation. In order to increase the leakage rate, the cathode electrode 3 is activated by the liquid fuel that has been cross-leaked during the pretreatment operation.

  As a result, according to such a pretreatment method for the fuel cell 1, it is possible to obtain the fuel cell 1 having excellent power generation performance in a shorter time.

  Examples of the use of the fuel cell 1 include a power source for a driving motor in an automobile, a ship, and an aircraft, and a power source in a communication terminal such as a mobile phone.

  Next, although this invention is demonstrated based on an Example and a comparative example, this invention is not limited by the following Example. The numerical values of the examples shown below can be substituted for the numerical values (that is, the upper limit value or the lower limit value) described in the embodiment.

Production Example 1
<Preparation of anode electrode ink>
Using an electronic balance, 3 g of unsupported metal catalyst (NiZn alloy (Ni: Zn = 87: 13 (molar ratio)), manufactured by Cabot), solvent (mixed solvent of 1-propanol and tetrahydrofuran (mass ratio 1: 1) ) 28.8 g (14.4 g + 14.4 g) and ionomer (hydrocarbon anion exchange resin having a quaternary ammonium group at the molecular end, manufactured by Tokuyama Corporation) 16.6 g were weighed and mixed.

Next, the obtained mixed liquid was stirred for about 10 minutes by operating a homogenizer (manufactured by Taitec Corp., VP-050) at an output of about 35% to obtain an anode electrode ink as a dispersion (slurry).
<Preparation of cathode electrode ink>
In an electronic balance, 2.2 g of a metal complex catalyst (compound name: cobalt polypyrrole carbon, product number D8L001, manufactured by Hokuko Chemical Co., Ltd.), solvent (mixed solvent of 1-propanol and tetrahydrofuran (mass ratio 1: 1)) 36.0 g (18.0 g + 18.0 g) and ionomer (hydrocarbon anion exchange resin having a quaternary ammonium group at the molecular end, manufactured by Tokuyama Corporation) 36.2 g were weighed and mixed.

Next, the obtained mixture was stirred for about 3 minutes by operating a homogenizer (manufactured by Taitec Corp., VP-050) at an output of about 40% to obtain a cathode electrode ink as a dispersion (slurry).
<Fabrication of fuel cell>
Using a hand spray gun, spray the anode electrode ink on one side of the electrolyte layer (hydrocarbon anion exchange resin having a quaternary ammonium group at the molecular end, manufactured by Tokuyama), and spray the cathode electrode ink on the other side. , the amount of supported catalyst after drying (after solvent volatilization) is, 2.5 mg / cm ² at the anode, it was uniformly applied so as to be 1.0 mg / cm ² at the cathode electrode.

Then, it dried at 25 degreeC for 30 minutes, the fuel side electrode was formed in the one side surface of the electrolyte layer, respectively, and the oxygen side electrode was formed in the other side surface, and the fuel cell was obtained.
<Assembly>
Sixty fuel cell units were stacked via a fuel supply member and an oxygen supply member to form a fuel cell as a cell stack.

Example 1
Liquid fuel (hydrated hydrazine 20% by mass + 1 mol / L KOH) is supplied at a flow rate of 0.1 L / min / cell to the fuel side channel of the fuel cell obtained in Production Example 1, while the oxygen supply channel is supplied The fuel cell was generated by supplying air at 10 L / min / cell.

  Further, the back pressure on the anode electrode side at this time was 20 kPa, and the pressure on the anode electrode was 25 kPa. The back pressure on the cathode electrode side was 5 kPa, and the pressure on the cathode electrode was 10 kPa.

  Under this condition, the fuel cell was allowed to generate electricity for 30 hours.

  Next, power generation was stopped by stopping the supply of liquid fuel and air.

  As a result, a pre-generated power generation fuel cell was obtained. In addition, power generation performance during pretreatment power generation was evaluated. The result is shown in FIG.

Comparative Example 1
Liquid fuel (hydrated hydrazine 10% by mass + 1 mol / L KOH) is supplied at a flow rate of 0.1 L / min / cell to the fuel side channel of the fuel cell obtained in Production Example 1, while the oxygen supply channel The fuel cell was generated by supplying air at 10 L / min / cell.

  Further, the back pressure on the anode electrode side at this time was 2 kPa, and the pressure on the anode electrode was 5 kPa. The back pressure on the cathode electrode side was 10 kPa, and the pressure on the cathode electrode was 15 kPa.

  Under this condition, the fuel cell was allowed to generate electricity for 30 hours.

  Next, power generation was stopped by stopping the supply of liquid fuel and air.

  As a result, a pre-generated power generation fuel cell was obtained. In addition, power generation performance during pretreatment power generation was evaluated. The result is shown in FIG.

Example 2 and Comparative Example 2
<Pretreatment condition 1>
Liquid fuel (hydrated hydrazine 20% by mass + 1 mol / L KOH) is supplied at a flow rate of 0.1 L / min / cell to the fuel side channel of the fuel cell obtained in Production Example 1, while the oxygen supply channel is supplied The fuel cell was generated by supplying air at 10 L / min / cell.

  Further, the back pressure on the anode electrode side at this time was 2 kPa, and the pressure on the anode electrode was 5 kPa. The back pressure on the cathode electrode side was 10 kPa, and the pressure on the cathode electrode was 15 kPa.

Under this condition, the fuel cell was allowed to generate power for 20 hours.
<Pretreatment condition 2>
Thereafter, liquid fuel (hydrated hydrazine 10% by mass + 1 mol / L KOH) is supplied to the fuel-side flow path of the fuel cell at a flow rate of 0.1 L / min / cell, while air is supplied to the oxygen supply path at 10 L / min. The fuel cell was caused to generate electricity by supplying at / cell.

  Further, the back pressure on the anode electrode side at this time was 20 kPa, and the pressure on the anode electrode was 25 kPa. The back pressure on the cathode electrode side was 5 kPa, and the pressure on the cathode electrode was 10 kPa.

  Under this condition, the fuel cell was allowed to generate power for 20 hours.

  Next, power generation was stopped by stopping the supply of liquid fuel and air.

  As a result, a pre-generated power generation fuel cell was obtained. In addition, power generation performance during pretreatment power generation was evaluated. The result is shown in FIG.

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Anode electrode 3 Cathode electrode 4 Electrolyte layer 15 Cell laminated body S Fuel cell

Claims (3)

A fuel cell pretreatment method comprising: an electrolyte layer; an anode electrode disposed opposite to the electrolyte layer, to which liquid fuel is supplied; and a cathode electrode to which oxygen is supplied,
A pre-processing operation step of pre-processing power generation of the fuel cell before the steady operation of generating the fuel cell constantly;
In the pretreatment operation step,
A pretreatment method for a fuel cell, characterized in that a rate at which the liquid fuel supplied to the anode electrode side leaks to the cathode electrode side is increased more than that during the steady operation. 2. The fuel cell pretreatment method according to claim 1, wherein the concentration of the liquid fuel during the pretreatment operation is increased more than that during the steady operation.   2. The fuel cell pretreatment method according to claim 1, wherein, during the pretreatment operation, a pressure applied to the anode electrode is set higher than a pressure applied to the cathode electrode. 3.

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