JP2005322534A - Test method of polyelectrolyte type fuel cell, and polyelectrolyte type fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a test method of a fuel cell for guaranteeing the performance of the fuel cell by grasping beforehand a deterioration phenomenon of the polyelectrolyte at the time of operation of the fuel cell, and a fuel cell having high reliability. <P>SOLUTION: This is a test method of a polyelectrolyte fuel cell which generates electric power by an electrochemical reaction by supplying a fuel gas and an oxidizer gas, and comprises an acceleration operation process of carrying out operation in a state where the operation temperature of the polyelectrolyte fuel cell is higher than the rated operation time and a judgement process of judging whether the polyelectrolyte fuel cell is acceptable or not acceptable based on the result of the acceleration operation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell used in a power source for portable devices, a portable power source, a power source for electric vehicles, a domestic cogeneration system, etc., in particular, an accelerated test method for a polymer electrolyte fuel cell, and a polymer electrolyte using this test method. Type fuel cell.

  A polymer electrolyte fuel cell performs power generation by allowing a fuel gas such as hydrogen and an oxidant gas such as air to react electrochemically with a gas diffusion electrode. A general configuration of such a polymer electrolyte fuel cell is shown in FIG.

  In FIG. 1, a catalytic reaction layer 2 mainly composed of carbon powder carrying a platinum-based metal catalyst is disposed in close contact with both surfaces of a polymer electrolyte membrane 3 that selectively transports hydrogen ions. Yes. Further, on the outer surface of the catalyst reaction layer 2, a pair of diffusion layers 1 having gas permeability and conductivity are disposed in close contact with the catalyst reaction layer 2. The diffusion layer 1 and the catalytic reaction layer 2 constitute an electrode 9.

  An electrode electrolyte assembly (hereinafter referred to as MEA) 10 formed of the electrode 9 and the polymer electrolyte membrane 3 is mechanically fixed outside the electrode 9 and the adjacent MEAs are electrically connected to each other. In addition, a conductive separator plate 4 is provided in which a gas flow path 5 for supplying a reaction gas to the electrode and carrying away a gas generated by the reaction or a surplus gas is formed on one surface. . The gas flow path 5 can be provided separately from the separator plate 4, but a system in which a groove is provided on the surface of the separator plate to form a gas flow path is common.

  On the other surface of the separator plate 4 is provided a cooling flow path 7 for circulating cooling water for keeping the battery temperature constant. By circulating the cooling water in this way, the heat energy generated by the reaction can be used in the form of hot water or the like.

  Further, a gas seal material is sandwiched around the electrode 9 so that hydrogen and air do not leak out of the battery or mix with each other, and further, cooling water does not leak out of the battery. 13 and an O-ring 14 are arranged.

  As is well known, it is known that a fuel cell deteriorates with time when operated for a long period of time. Examples of the deteriorated part include an electrode catalyst, a polymer electrolyte membrane, and a gas diffusion layer. In the phosphoric acid fuel cell, an increase in the particle diameter of the electrode catalyst and a change in wettability of the electrode part are considered as causes of deterioration.

  In the case of a polymer electrolyte fuel cell, the battery performance also deteriorates due to deterioration of the polymer electrolyte membrane. Although the degradation mechanism of polymer electrolyte membranes has not been fully elucidated, it is thought that peroxides such as hydrogen peroxide generated as a side reaction of the electrocatalytic reaction are radicalized to erode the electrolyte membrane and promote degradation. Yes.

  As the polymer electrolyte, a perfluorocarbon sulfonic acid membrane (for example, a product name: Nafion membrane manufactured by DuPont, USA) is generally used. Although such a fluorine-based electrolyte membrane is considered to be a material excellent in oxidation resistance, it has recently been reported that even such a membrane is deteriorated by a radical reaction (for example, see Non-Patent Document 1). .) Also, hydrocarbon electrolyte membranes that are less expensive than fluorine-based electrolyte membranes have been developed, but it is generally considered that oxidation resistance is lower than that of fluorine-based electrolyte membranes.

  If the polymer electrolyte membrane has defects or the like, and such deterioration progresses at an accelerated rate, the polymer electrolyte membrane may be fatally damaged in a short time, and there is a risk that battery operation becomes impossible. When the fuel cell is operated for a long period of time, it is necessary to appropriately inspect such dangers as deterioration of the battery performance and breakage of the electrolyte membrane before the battery operation. In addition, it is indispensable to accurately determine the deterioration phenomenon of the polymer electrolyte in a short time and to guarantee the performance as a fuel cell in advance in order to guarantee the quality of the fuel cell.

Until now, as a method for guaranteeing the cell performance of a polymer electrolyte fuel cell, there is a method in which helium gas is injected into a fuel gas channel, an oxidant gas channel, etc., and the amount of gas leakage is accurately detected in advance. (For example, see Patent Document 1). If this method is used, the amount of gas leakage from the fuel cell can be ascertained, and therefore it is possible to determine in advance whether the gas sealing performance is good or bad.
JP 2002-334713 A FCDIC Symposium Committee's “10th Fuel Cell Symposium Proceedings” published by Fuel Cell Development Information Center (FCDIC), May 13, 2003, P261-264

  As described above, it is important from the viewpoint of quality assurance that helium gas or the like is injected into the supply gas flow path of the fuel cell and the amount of gas leakage from the fuel cell is determined in advance. This method is also effective as a method for evaluating the gas sealability of various sealing materials used in fuel cells and for determining the initial leakage due to physical defects of the MEA. However, a special inspection device such as helium gas or a leak detector for detecting gas leakage is required.

  In addition, since an inspection method that is not in the power generation state is used, it is difficult to perform quality assurance regarding the deterioration of the polymer electrolyte membrane during battery operation.

  In consideration of the above-described conventional problems, the present invention can simulate degradation of the polymer electrolyte during fuel cell operation by acceleration, or can grasp the degradation of the polymer electrolyte in advance to guarantee the performance. It is an object of the present invention to provide a test method for a polymer electrolyte fuel cell and a polymer electrolyte fuel cell using the test method.

In order to achieve the above object, the first present invention provides:
A test method for a polymer electrolyte fuel cell in which fuel gas and oxidant gas are supplied and electric power is generated by an electrochemical reaction,
An accelerating operation step of operating in a state where the operating temperature of the polymer electrolyte fuel cell is higher than that during rated operation;
A test method for a polymer electrolyte fuel cell, comprising: a determination step of determining whether the polymer electrolyte fuel cell is acceptable or unacceptable based on a result of the acceleration operation.

The second aspect of the present invention is
A test method for a polymer electrolyte fuel cell in which fuel gas and oxidant gas are supplied and electric power is generated by an electrochemical reaction,
An acceleration operation step of operating in a state where the dew point of the fuel gas and / or the oxidant gas supplied to the polymer electrolyte fuel cell is lower than that during rated operation;
It is a test method for a polymer electrolyte fuel cell, comprising a determination step for determining whether the polymer electrolyte fuel cell is acceptable or not based on a result of the acceleration operation.

The third aspect of the present invention
In the determination step, the voltage drop rate of the polymer electrolyte fuel cell at the time of the acceleration operation is expressed by the formula (1) as compared with the voltage drop rate at the rated operation of the reference polymer electrolyte fuel cell. If it is Y times, it is the test method for the polymer electrolyte fuel cell of the first or second aspect of the present invention in which the polymer electrolyte fuel cell is determined to be acceptable.

The fourth aspect of the present invention is
In the determination step, the voltage drop rate of the polymer electrolyte fuel cell during the acceleration operation is 1 of the voltage drop rate of the reference polymer electrolyte fuel cell during the acceleration operation under the same conditions as the acceleration operation. The test method for the polymer electrolyte fuel cell according to the first or second aspect of the present invention, in which the polymer electrolyte fuel cell is determined to be acceptable when the ratio is less than 5 times.

The fifth aspect of the present invention is
The voltage drop rate during rated operation or acceleration operation of the reference polymer electrolyte fuel cell is an average value of voltage drop rates of a plurality of polymer electrolyte fuel cells. It is a test method for a polymer electrolyte fuel cell of the invention.

The sixth aspect of the present invention
The voltage drop rate during rated operation or accelerated operation of the reference polymer electrolyte fuel cell is the smallest value of the voltage drop rates of the plurality of polymer electrolyte fuel cells. It is a test method for a polymer electrolyte fuel cell of the present invention.

The seventh aspect of the present invention
In the polymer electrolyte fuel cell serving as the reference, the voltage drop rate during the acceleration operation is substantially Z times the voltage drop rate during the rated operation shown in the equation (2). It is a test method for a polymer electrolyte fuel cell of the present invention.

  According to an eighth aspect of the present invention, in the determination step, the amount of decomposition product of the polymer electrolyte contained in the exhaust gas discharged from the polymer electrolyte fuel cell during the acceleration operation is a reference polymer. If the amount of decomposition product during the rated operation of the electrolyte fuel cell is Y times represented by the formula (1), the polymer electrolyte fuel cell is determined to be acceptable. This is a test method for a molecular electrolyte fuel cell.

The ninth aspect of the present invention provides
In the determination step, a decomposition product amount of the polymer electrolyte contained in the exhaust gas discharged from the polymer electrolyte fuel cell at the time of the acceleration operation becomes a reference when the acceleration operation is performed under the same conditions as the acceleration operation. In the first or second embodiment, when the amount of decomposition product of the polymer electrolyte contained in the exhaust gas discharged from the polymer electrolyte fuel cell is less than 1.5 times, the polymer electrolyte fuel cell is passed. It is a test method for a polymer electrolyte fuel cell of the present invention.

The tenth aspect of the present invention is
The eighth or ninth book, wherein the amount of decomposition products during rated operation or acceleration operation of the reference polymer electrolyte fuel cell is an average value of the amount of decomposition products of a plurality of polymer electrolyte fuel cell types It is a test method for a polymer electrolyte fuel cell of the invention.

The eleventh aspect of the present invention is
The amount of the decomposition product during rated operation or acceleration operation of the reference polymer electrolyte fuel cell is the smallest value of the amount of decomposition products of the plurality of polymer electrolyte type annual cells. This is a test method for a polymer electrolyte fuel cell of the present invention.

The twelfth aspect of the present invention is
In the reference polymer electrolyte fuel cell, the eighth or ninth book is such that the amount of decomposition products during the accelerated operation is substantially Z times the amount of decomposition products during the rated operation shown in the equation (2). It is a test method for a polymer electrolyte fuel cell of the invention.

The thirteenth aspect of the present invention is
The decomposition product amount is the amount of fluorine ions, the test method for a polymer electrolyte fuel cell according to any one of the eighth to twelfth aspects of the present invention.

The fourteenth aspect of the present invention is
In the polymer electrolyte fuel cell serving as the reference, the polymer electrolyte fuel cell test method of the thirteenth aspect of the present invention is such that the amount of fluorine ions in the exhaust gas during the rated operation is 1.0 μg / hour or less. It is.

The fifteenth aspect of the present invention is
It is a polymer electrolyte fuel cell determined to be acceptable using any one of the first to fourteenth polymer electrolyte fuel cell test methods of the present invention.

  According to the present invention, there is provided a polymer electrolyte fuel cell capable of simulating deterioration of a polymer electrolyte during operation of the fuel cell by acceleration, or grasping deterioration of the polymer electrolyte in advance and guaranteeing performance. A test method and a polymer electrolyte fuel cell using the test method can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
First, using the polymer electrolyte fuel cell shown in FIG. 1, the battery is operated under the conditions (BD) where the operating temperature is higher than the battery temperature during rated operation (Tcell (1)). It was. The fuel cell used in the present embodiment has the same configuration as the fuel cell described in (Background Art). The temperature of the polymer electrolyte fuel cell of the present invention usually corresponds to the temperature in the vicinity of the inlet of the cooling water pipe for cooling the fuel cell to the fuel cell stack.

Here, each value is shown as follows.
Tcell (1): Battery temperature during rated operation Tcell (2): Battery temperature during acceleration test ΔTa (1): Battery temperature during rated operation (Tcell (1)) and fuel gas dew point (Tad (1)) Difference ΔTa (2): Battery temperature during acceleration test (Tcell (2)) and fuel gas dew point (Tad (2)) ΔTc (1): Battery temperature during rated operation (Tcell (1)) and oxidizing agent Difference of gas dew point (Tcd (1)) ΔTc (2): Difference between battery temperature (Tcell (2)) and oxidant gas dew point (Tcd (2)) during acceleration test The battery temperature was 60 ° C., hydrogen gas (fuel utilization rate 80%) was passed through the fuel electrode, and air (air utilization rate 40%) was passed through the air electrode.

  Table 1 shows the difference between the battery temperature, the supply gas dew point, and the rated operating temperature under each operating condition. In rated operation (A), the battery temperature and the dew point of each supply gas are the same. In addition, the dew point of each supply gas and the battery temperature are the same under the BD conditions when the battery temperature is increased. I tried to become. In the B condition, the battery temperature was set 5 ° C. higher than the rated condition, in the C condition, the battery temperature was set 10 ° C. higher than the rated condition, and in the D condition, the battery temperature was set 15 ° C. higher than the rated condition.

  The relationship between the battery voltage and the operation time at this time is shown in FIG. In FIG. 2, it can be seen that the decrease in battery voltage increases as the battery temperature increases. For example, a decrease in battery voltage in rated operation A after lapse of 2000 hours corresponds to a decrease in battery voltage after lapse of 500 hours in test condition C. This indicates that the 500 hour test under the condition C corresponds to an accelerated test for 2000 hours in the rated operation A.

  In the case where the polymer electrolyte membrane of the polymer electrolyte fuel cell of Embodiment 1 is a fluorine-based electrolyte membrane, when the polymer electrolyte membrane deteriorates due to the attack of hydroxy radicals, the main components constituting the membrane The component fluorine elutes into the drain water in the off-gas. Therefore, the amount of precipitated fluorine ions can be used as an indicator of deterioration of the polymer electrolyte membrane.

  FIG. 3 is a configuration diagram of an apparatus for measuring the amount of fluorine ions deposited when the fuel cell is deteriorated. As shown in FIG. 3, this apparatus collects the exhaust gas of the anode gas of the polymer electrolyte fuel cell 15 in the anode drain tank 16 and collects the exhaust gas of the cathode gas in the cathode drain tank 17. The anode drain water is sent to the cathode drain tank 17 by the pump 18 and the amount of fluorine ions in the total collected drain water is measured over time. From this, the amount of fluorine ions per hour was calculated.

Table 2 shows the voltage drop rate and the fluorine ion amount under the conditions BD when the voltage drop rate per 1000 hours and the fluorine ion amount under the rated condition A are normalized to 1, respectively. The voltage drop rate of the present invention is, for example, ((Vt−V.) / T) in the first embodiment, where the initial voltage is V ₀ and the voltage drop amount per predetermined time t is Vt. It is a value represented by x100.

From this, it was found that both the voltage drop rate and the amount of fluorine ions increased under the B, C, and D conditions where the battery temperature was higher than the oxidizing gas dew point with respect to the rated conditions. This is considered to be because the deterioration of the polymer electrolyte was promoted by increasing the battery temperature. Each value is approximately 2 ^{(ΔTcell / 10)} at rated operation, where ΔTcell is the difference between the battery temperature under each condition (Tcell (2)) and the rated battery temperature (Tcell (1) ^). It turns out that it doubles.

  Next, battery operation was performed under conditions (EG) as shown in Table 3 in which the dew point of the oxidant gas was kept at the rated condition when the battery temperature was increased. In condition E, the battery temperature and the fuel gas dew point are both set to 5 ° C. higher than the rated condition A. In condition F, both the battery temperature and the fuel gas dew point are set to 10 ° C. higher than the rated condition A. The fuel gas dew point was set 15 ° C. higher than the rated condition A.

  The relationship between the battery voltage and the operation time at this time is shown in FIG. In the graph of FIG. 4, it can be seen that the decrease in the battery voltage accompanying the temperature rise is larger than that in the graph of FIG. 2.

  Table 4 shows the voltage drop rate and the fluorine ion amount under each condition when the voltage drop rate per 1000 hours and the fluorine ion amount under the rated conditions are normalized to 1 respectively.

  At this time, when Z is a ratio of the voltage drop rate or the amount of fluorine ions at the time of accelerated operation to the rated operation, it has been found that each value substantially matches the value represented by the following formula (3).

For example, when this condition is applied to the condition F, it becomes as follows.
Z = (2 ^(10/10) × 2 ^{((0-0) / 10)} × 2 ^{((10-0) / 10)} ) = 4
From this, when the formula (3) was used, the voltage drop rate and the amount of fluorine ions were in good agreement.

  Next, the case where the battery temperature was increased contrary to the above and the oxidant gas dew point was increased similarly to the battery temperature and only the fuel electrode gas dew point was made the same as the rated condition was also examined. As a result, the voltage drop rate and fluorine ion amount under other conditions when the voltage drop rate per 1000 hours under rated conditions and the fluorine ion amount are each normalized to 1 are calculated from the previous equation (3). The result was in good agreement with the value.

  Next, the case where the battery temperature of rated condition A was left as it was and the dew point of each supply gas was 10 ° C. lower than the battery temperature (rated condition A ′) was examined.

  Further, as shown in Table 5, the battery test was performed under the H condition in which the battery temperature and the fuel gas dew point were set 5 ° C. higher than the rated condition A ′.

  As a result, the voltage drop rate and the fluorine ion elution amount under the H condition when the voltage drop rate per 1000 hours and the fluorine ion elution amount are normalized to 1 for the rated condition A ′ are 1.9, 2. 0.

Here, when the condition H is applied to the expression (3), the following is obtained.
Z = (2 ^(5/10) × 2 ^{((10-10) / 10)} × 2 ^{((15-10) / 10)} ) = 2
From this, when the formula (3) was used, the voltage drop rate and the amount of fluorine ions were in good agreement.

  This method can provide a test method that can determine the durability of a battery in a short time by setting conditions that increase the battery temperature or lower the relative humidity, regardless of what operating conditions are rated operation. . For example, when the acceleration test is performed under condition C, a test corresponding to 2000 hours of rated operation can be performed in 500 hours. When the acceleration test is performed under the condition G, the test corresponding to the rated operation 2000 hours can be performed in about 100 hours.

  As a method of lowering the relative humidity of the fuel gas and oxidant gas, various settings can be made according to each rated test condition. In addition to increasing the battery temperature, each supply gas dew point can be kept at the same battery temperature. Can be set lower than the rated condition. Any difference can be selected as long as the difference between the battery temperature during rated operation and the dew point of each supply gas can be made larger than during rated operation.

(Embodiment 2)
Next, a fuel cell using the test method shown in Embodiment 1 will be described. Using condition F, 10 types of MEAs (a to j) having different production lots were tested and evaluated. In addition, tests were also performed for rated operation conditions for each of the ten types of MEAs.

  The relationship between the rated voltage A and the voltage drop rate of the battery under the condition F at this time is shown in FIG. 5, and the relationship between the fluorine ion elution amounts is shown in FIG. The voltage drop rate and the fluorine ion content of production lot a were normalized to 1 under the rated conditions. The production lot a is a lot that satisfies the conditions of the first embodiment, and is a lot that satisfies the absolute value of the fluorine ion deposition amount of 1.0 μg / less under the rated conditions.

  As shown in FIGS. 5 and 6, it was found that when the voltage drop rate under condition F is 6 or more, the voltage drop rate under condition A, which is the rated condition, also increases. It was also found that when the amount of fluorine ions under condition F was 6 or more, the amount of fluorine ions under rated conditions also increased.

  Z in the formula (3) represents the ratio of the accelerated operation to the rated operation of the voltage drop rate or the amount of deposited fluorine ions in the reference lot a. Therefore, taking the voltage drop rate as an example, if the voltage drop rate under the condition A (rated) in the reference lot a is aAv, and the voltage drop rate under the acceleration condition under the condition F is aFv, substantially aFv = 4 -AAv is established.

  Here, if the correction coefficient between lots is α, for example, if the voltage drop rate under the condition F of lot b is bFv, it can be expressed as bFv = α · aFv, and bFv = 4 · α · aAv. Can be expressed as Assuming that the voltage reduction rate of lot b when standardizing the voltage reduction rate of reference lot a under condition F as 1 is bYF, bYF = bFv / aAv = 4 · α.

  Although lot b has been described above, when this is extended to other lots, the voltage drop rate under the condition F of other lots is set to Fv, and the voltage drop rate of the reference lot is set to 1. If the voltage drop rate is YF, YF = Fv / aAv = 4 · α.

  Furthermore, since the acceleration test was performed under the condition F, a constant of 4 was derived from the expression (3). However, when the expression (3) that changes depending on the acceleration condition is used to expand to other conditions, the following expression (4) is obtained. To establish.

  As described above, in the graph of FIG. 5, when the voltage drop rate (Y) under the condition F is 6 or more, the voltage drop rate under the condition A is also low. Therefore, when the value of α is 1.5 or more. It was found that the voltage drop rate, which is a characteristic during rated operation, deteriorates.

  As in the case of the voltage drop rate, the above equation (4) is also established for the fluorine ion amount, and as shown in FIG. 6, the fluorine ion amount is bad when the value of α is 1.5 or more. I found out that

  From this, it was found that it is optimal from the viewpoint of quality assurance to use an MEA in which the voltage drop rate and the fluorine ion amount under condition F are α <1.5.

  Similarly, the conditions E and G performed in the first embodiment were similarly evaluated for 10 types of MEAs with different production lots. When α ≧ 1.5, the voltage drop rate and the amount of fluorine ions were In this case, the voltage drop rate under rated conditions increased and the amount of fluorine ions increased.

  Here, attention is focused on fluorine ions as a decomposition product of the polymer electrolyte. However, when a polymer film other than a fluorine-based polymer film is used, the present invention is not limited to this and can be changed according to the material to be used.

  That is, for the MEA extracted from each of a plurality of lots, an accelerated test is performed under predetermined conditions (battery temperature, fuel gas dew point, and oxidant gas dew point). By accepting a lot smaller than 1.5 times the reference lot at the time of the acceleration test, it becomes possible to determine whether or not the quality is satisfied for each lot. In the fuel cell inspection method of the present invention, since it is inspected whether the quality is satisfied by actually operating it, it is more accurate, and since the test is performed under acceleration conditions, the inspection is performed in a shorter time. Can be done.

  In the second embodiment, a lot a satisfying the formula (3) of the first embodiment and satisfying the absolute value of the amount of deposited fluorine ions in the rated operation of 1.0 μg / below is used as the reference lot. Although it has been shown that other lots can be discriminated, the following may be performed. Other discrimination methods are shown below.

  For example, a lot whose voltage drop amount under rated operating conditions is 10 μV / hour or less is used as a reference lot, and an acceleration test is performed on lots a to j under condition F in the same manner as described above. A lot having a voltage drop rate of 1.5 times or more is determined as a defective product.

  Also, the lots a to j are subjected to an acceleration test under the condition F, and the lot with the smallest voltage drop is used as a reference. A lot having a voltage drop rate of 1.5 times or more of the voltage drop rate in the condition F of the reference lot is determined as a defective product.

  Also, lots a to j are subjected to an acceleration test under condition F, and the lot having the smallest fluorine ion deposition amount is used as a reference, and a lot having 1.5 times or more fluorine ions deposited as a reference lot is identified as a defective product. To do. Here, when determining the reference lot, a threshold value that the amount of fluorine ions in the rated operation is 1.0 μg / hour or less may be provided.

  Furthermore, the reference lot may be determined by arbitrarily combining the three conditions of the first embodiment, the condition that the voltage drop is the smallest, and the condition that the fluorine ion deposition amount is the smallest.

  In the second embodiment, an acceleration test is performed under the condition F for discrimination. However, if the difference between the battery temperature during rated operation and each supply gas dew point can be made larger than during rated operation, The above determination is valid under any acceleration test conditions. The above equation of bFv = α · aFv is satisfied when the acceleration test condition is any of the above-described conditions B to E (bBv = α · aBv under condition B). That is, measure the voltage drop rate or fluoride ion deposition amount of the reference lot and other lots under the same accelerated test conditions, and improve the quality for lots with a voltage drop rate or fluoride ion deposition amount less than 1.5 times the reference lot. It can be determined that it is satisfied.

  Further, in the second embodiment, the reference lot a is also subjected to an acceleration test under the same conditions as the other lots b to j and is determined with 1.5 times the reference lot as a threshold value. It may be based on the voltage drop rate or the amount of deposited fluorine ions in the rated operation of the set standard lot.

  Specifically, an acceleration test of lots b to j is performed according to the condition F. When α <1.5 (the determination threshold obtained in the second embodiment) is applied from Fv = 4 · α · aAv described above, Fv <6 · aAv. Thus, the lots b to j under the condition F have a voltage drop rate or fluorine ion deposition amount that is less than 6 times the voltage drop rate or fluoride ion deposition amount during rated operation of the reference lot a. Can be determined. Needless to say, the threshold value for discrimination based on the voltage drop rate or the fluorine ion amount at the rated operation of the reference lot can be determined by applying the formula (4) to other acceleration test conditions.

  The formula (3) shown in the first embodiment corresponds to the formula (2) of the present invention. In the formula (4) shown in the second embodiment, the case where α <1.5 It corresponds to the formula (1).

  The embodiment of the present invention will be described more specifically as an example.

(Example 1)
First, an electrode with a catalyst layer provided with a gas diffusion layer was attached to a polymer electrolyte membrane (manufactured by DuPont, Nafion membrane, thickness 50 μm) to prepare an MEA.

  The MEA was sandwiched between a carbon separator plate having airtightness from both sides and a silicon rubber gas sealing material to constitute a single cell. Two cells of the above unit cell were stacked to obtain a battery structural unit, and a fuel cell stack was prepared with the configuration shown in FIG. The laminated unit cells consisted of 10 cells in total, and a laminated battery was prepared by arranging a copper current collector plate plated with gold at both ends, an insulating plate made of an electrically insulating material, and an end plate in order.

  In the fuel cell stack, hydrogen gas is flowed to the fuel electrode as oxidant gas to the fuel electrode, the cooling water inlet temperature (cell temperature) is 75 ° C., the fuel utilization rate is 80%, and the air utilization rate is The fuel cell was operated by adjusting the gas humidification so that the dew point was 75 ° C. for hydrogen gas and 75 ° C. for air. This condition was set as the rated condition.

  At this time, the anode and cathode exhaust gas was circulated through a drain tank configured as shown in FIG. 3 to collect drain water. For the measurement of the fluorine ion concentration, an ion chromatogram (ICS-90, manufactured by Nippon Dionex) was used, and the elution rate was calculated from the fluorine ion concentration in the drain water.

  Next, the test was conducted under the conditions shown in Table 6 where the battery temperature was higher than the rated conditions. The test was performed under the same conditions as the rated conditions except for those shown in (Table 6). As conditions shown in Table 6, in condition I, the battery temperature was set to 85 ° C., the dew point of the fuel gas was set to 85 ° C., and the dew point of the oxidant gas was set to 85 ° C. In condition J, the battery temperature was set to 95 ° C., the fuel gas dew point was set to 95 ° C., and the oxidant gas dew point was set to 95 ° C.

  The relationship between the battery voltage and the durability time at this time is shown in FIG. 7 together with the rated conditions. FIG. 8 shows a comparison of fluorine ion elution rates under various conditions.

From the results of FIGS. 7 and 8, it was found that both the voltage drop rate and the amount of fluorine ions were approximately 2 ^{(ΔTcell / 10)} times.

  The test was also conducted on the conditions shown in Table 7 where the fuel gas dew point and the oxidant gas dew point were lowered relative to the rated conditions. As the conditions shown in Table 7, under the condition K, the battery temperature was set to 75 ° C., the fuel gas dew point was set to 75 ° C., and the oxidant gas dew point was set to 60 ° C. In condition L, the battery temperature was set to 75 ° C., the fuel gas dew point was set to 60 ° C., and the oxidant gas dew point was set to 60 ° C.

  Also about this, it turned out that both a voltage fall rate and the amount of fluorine ions become about 2.8 times and 8 times, and it turned out that it corresponds with the value derived | led-out from Formula (3) substantially.

  From this, it was found that deterioration was accelerated as described above under conditions I and J where the battery temperature was increased with respect to the rated conditions and conditions K and L where the supply gas dew points were lowered.

  Here, the rated condition is a fully humidified state in which the battery temperature and each supply gas dew point are the same, but the rating condition is not limited to this, and the case where each supply gas dew point is lower than the battery temperature is also applicable. Other test conditions are not limited to the present embodiment, and any method may be used as long as the present invention is applicable.

(Example 2)
Next, using the accelerated test condition J used in Example 1 (cell temperature is 95 ° C., fuel gas dew point is 95 ° C., oxidant gas dew point is 95 ° C.), the production conditions are the same. Tests of MEAs (1-5) with different production lots were performed. In the same manner as in Example 1, each MEA was incorporated to constitute a fuel cell, and a battery test was conducted. Test conditions other than the battery temperature and the fuel gas dew point were the same as the rated conditions of Example 1. In addition, MEA1 was the same lot used in Example 1, and this MEA1 was used as a reference lot.

  FIG. 9 shows changes with time in these battery voltages. The dotted line in the figure shows a voltage curve that is 1.5 times the voltage drop rate of MEA 1 in the accelerated test under condition J. In other words, this dotted line, when applied to the equation (4), shows a voltage curve with a voltage drop rate that is six times the voltage drop rate during the rated operation of the MEA 1. The voltage drop curve indicated by the dotted line is a determination line for determining whether or not the quality is satisfied.

  From FIG. 9, it was found that the voltage drop of MEA 4 was the largest among the MEAs and was lower than the dotted voltage curve. Therefore, when this MEA 4 was tested under rated conditions, it was found that the voltage drop rate was larger than that of MEA 1.

  Further, other MEAs were also tested under rated conditions, but the voltage drop rate was almost the same as MEA1. From this, it was found that by using the equation (4) from the voltage drop rate of the test condition J, it is possible to determine the characteristic drop under the rated condition.

  Similarly, the amount of fluorine ions during the test was also measured and examined for each MEA. The result is shown in FIG. The dotted line in the figure indicates a value that is 1.5 times the fluorine ion deposition amount per hour of MEA 1 by the acceleration test under condition J. In other words, the dotted line indicates a value that is six times the amount of fluorine ions at the rated conditions of MEA1.

  The MEA 4 exceeded the dotted line. It was found that the amount of fluorine ions under the rated conditions of MEA4 also increased compared to MEA1. As a result, it was found that the deterioration of characteristics can also be determined under test condition J for the fluorine ion amount.

  In this embodiment, the acceleration test was performed under the condition that the battery temperature was increased by 20 ° C. However, other conditions may be used, and the battery temperature may be left as it is to reduce the dew point of each supply gas. it can. Also, the rated condition is not limited to the present embodiment, and the voltage drop rate and the fluorine ion amount may be α <1.5 or less in the equation (4) as compared to the rating test. In this example, since the fluorine-based polymer electrolyte membrane was used, the amount of fluorine ions was used as an index. However, for example, when a hydrocarbon-based membrane is used, these decomposition products should be used as an index instead of fluorine ions. I can do it. Oxidant gas and fuel gas composition, battery temperature, humidification conditions, etc. are not limited to the present embodiment.

  By using the present invention, for example, several MEAs are extracted for each production lot, and by performing such an acceleration test, the reliability of the fuel cell can be evaluated in advance, and MEAs that have not cleared the acceleration test are eliminated. By doing so, a highly reliable fuel cell can be constructed.

  A method for inspecting a polymer electrolyte fuel cell according to the present invention and a polymer electrolyte fuel cell using this test method can simulate deterioration of a polymer electrolyte during operation of the fuel cell by acceleration, or Test method for fuel cells such as power supplies for portable devices, power supplies for portable devices, fuel cell automobiles or household fuel cell cogeneration systems, etc. It is also applicable to.

Schematic sectional view showing the general structure of a polymer electrolyte fuel cell The figure which shows the time passage of the battery voltage in the acceleration conditions BD and the rated condition A which are the test methods of the polymer electrolyte fuel cell of Embodiment 1 concerning this invention 1 is a configuration diagram of an apparatus for measuring the amount of deposited fluorine ions in a test method for a polymer electrolyte fuel cell according to a first embodiment of the present invention. The figure which shows the time passage of the battery voltage in the acceleration conditions EG and the rated conditions A which are the test methods of the polymer electrolyte fuel cell of Embodiment 1 concerning this invention The figure which shows the difference of the voltage drop rate in the production lot in the acceleration condition F which is the test method of the polymer electrolyte fuel cell of Embodiment 2 concerning this invention, and the rated condition A The figure which shows the difference of the amount of fluorine ions in the production lot in the acceleration condition F and the rated condition A which are the test methods of the polymer electrolyte fuel cell of Embodiment 2 concerning this invention The figure which shows the time passage of the battery voltage in the acceleration conditions I and J which are the test methods of the polymer electrolyte fuel cell of Example 1 concerning this invention, and the rated conditions A The figure which shows the difference of the amount of fluorine ions in the acceleration conditions I and J which are the test methods of the polymer electrolyte fuel cell of Example 1 concerning this invention, and the rated conditions A The figure which shows the time passage of the difference of the voltage drop rate in the production lot in the acceleration condition J which is a test method of the polymer electrolyte fuel cell of Example 2 concerning this invention The figure which shows the difference of the amount of fluorine ions in the production lot in the acceleration condition J which is a test method of the polymer electrolyte fuel cell of Example 2 concerning this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Diffusion layer 2 Catalytic reaction layer 3 Polymer electrolyte membrane 4 Separator plate 5 Gas flow path 7 Cooling water flow path 9 Electrode 10 MEA
13 Gas Seal Material 14 O-ring 15 Polymer Electrolyte Fuel Cell 16 Anode Drain Tank 17 Cathode Drain Tank 18 Pump

Claims (15)

A test method for a polymer electrolyte fuel cell in which fuel gas and oxidant gas are supplied and electric power is generated by an electrochemical reaction,
An accelerating operation step of operating in a state where the operating temperature of the polymer electrolyte fuel cell is higher than that during rated operation;
A test method for a polymer electrolyte fuel cell, comprising: a determination step for determining whether the polymer electrolyte fuel cell is acceptable or unacceptable based on a result of the acceleration operation. A test method for a polymer electrolyte fuel cell in which fuel gas and oxidant gas are supplied and electric power is generated by an electrochemical reaction,
An acceleration operation step of operating in a state where the dew point of the fuel gas and / or the oxidant gas supplied to the polymer electrolyte fuel cell is lower than that during rated operation;
A test method for a polymer electrolyte fuel cell, comprising: a determination step for determining whether the polymer electrolyte fuel cell is acceptable or unacceptable based on a result of the acceleration operation. In the determination step, the voltage drop rate of the polymer electrolyte fuel cell at the time of the acceleration operation is expressed by the formula (1) as compared with the voltage drop rate at the rated operation of the reference polymer electrolyte fuel cell. 3. The test method for a polymer electrolyte fuel cell according to claim 1, wherein the polymer electrolyte fuel cell is determined to be acceptable if it is Y times.

  In the determination step, the voltage drop rate of the polymer electrolyte fuel cell during the acceleration operation is 1 of the voltage drop rate of the reference polymer electrolyte fuel cell during the acceleration operation under the same conditions as the acceleration operation. The test method for a polymer electrolyte fuel cell according to claim 1, wherein the polymer electrolyte fuel cell is determined to be acceptable when the ratio is less than 5 times.   The voltage drop rate during rated operation or acceleration operation of the polymer electrolyte fuel cell serving as the reference is an average value of voltage drop rates of a plurality of polymer electrolyte fuel cells. A test method for a polymer electrolyte fuel cell according to the description.   5. The voltage drop rate during rated operation or acceleration operation of the polymer electrolyte fuel cell serving as the reference is the smallest value of the voltage drop rates of a plurality of polymer electrolyte fuel cells. 4. A test method for a polymer electrolyte fuel cell according to 1. 5. The reference polymer electrolyte fuel cell according to claim 3 or 4, wherein the voltage drop rate during the accelerated operation is substantially Z times the voltage drop rate during the rated operation shown in the equation (2). A test method for a polymer electrolyte fuel cell according to the description.

  The determination step is performed at the rated operation of the polymer electrolyte fuel cell based on the amount of decomposition product of the polymer electrolyte contained in the exhaust gas discharged from the polymer electrolyte fuel cell during the acceleration operation. 3. The method for testing a polymer electrolyte fuel cell according to claim 1, wherein the polymer electrolyte fuel cell is determined to be acceptable if the amount of decomposition product of Y is Y times represented by formula (1).   In the determination step, a decomposition product amount of the polymer electrolyte contained in the exhaust gas discharged from the polymer electrolyte fuel cell at the time of the acceleration operation becomes a reference when the acceleration operation is performed under the same conditions as the acceleration operation. The polymer electrolyte fuel cell is accepted when it is less than 1.5 times the amount of polymer electrolyte decomposition products contained in the exhaust gas discharged from the polymer electrolyte fuel cell. 4. A test method for a polymer electrolyte fuel cell according to 1.   The amount of the decomposition product during rated operation or acceleration operation of the reference polymer electrolyte fuel cell is an average value of the amount of decomposition products of a plurality of polymer electrolyte fuel cell types. A test method for a polymer electrolyte fuel cell according to the description.   The amount of the decomposition product during rated operation or acceleration operation of the reference polymer electrolyte fuel cell is the smallest value of the amount of decomposition products of a plurality of polymer electrolyte type annual cells. 4. A test method for a polymer electrolyte fuel cell according to 1.   In the polymer electrolyte fuel cell serving as the reference, the amount of decomposition products during the acceleration operation is substantially Z times the amount of decomposition products during the rated operation shown in the equation (2). A test method for a polymer electrolyte fuel cell according to the description.   The test method for a polymer electrolyte fuel cell according to any one of claims 8 to 12, wherein the decomposition product amount is an amount of fluorine ions.   The polymer electrolyte fuel cell test method according to claim 13, wherein the reference polymer electrolyte fuel cell has a fluorine ion amount in the exhaust gas during the rated operation of 1.0 µg or less / hour.   A polymer electrolyte fuel cell determined to be acceptable by using the test method for a polymer electrolyte fuel cell according to claim 1.

Images