JP4468234B2 - Liquid fuel for fuel cell, fuel cartridge for fuel cell, and fuel cell - Google Patents

Description

  The present invention relates to a liquid fuel for a fuel cell, a fuel cartridge for a fuel cell, and a fuel cell.

In a fuel cell, fuel such as hydrogen and methanol is electrochemically oxidized in the battery, thereby converting the chemical energy of the fuel directly into electric energy and taking it out. Therefore, since there is no occurrence of NO _x and SO _x from the combustion of the fuel as thermal power, it has attracted attention as a clean electric energy supply source.

  Among them, the direct liquid fuel cell can be miniaturized and has been actively developed as a portable fuel cell. Various types of direct liquid fuel cells are known, such as a liquid fuel supply type and those using a capillary force, and alcohol, formic acid, an aqueous solution thereof, and the like are used as fuel. On the other hand, in a portable fuel cell, how to replenish fuel is the key to continuous power generation. Therefore, as one of the fuel supply methods, if the fuel cartridge main body and the fuel cartridge that can be connected to the fuel cell main body are separated, the fuel cell can be continuously generated by replacing the fuel cartridge.

  In the above fuel cell, the fuel cartridge is essential for continuous power generation. On the other hand, in the direct liquid fuel type fuel cell, since the fuel is directly supplied to the power generation element (MEA: membrane electrode assembly), it has a drawback that it is very easily affected by impurities in the fuel. Since the fuel itself is synthesized and prepared by various methods, many ionic impurities may be mixed. Further, the concentration of fuel used in the fuel cartridge is required to be increased in order to increase the volume energy density. Therefore, there is a possibility that ionic impurities and the like are eluted by the fuel.

Patent Documents 1 and 2 both relate to a fuel container for a fuel cell including a container body having a sealed structure and a valve mechanism for opening and closing the supply of stored fuel. It is disclosed that by using a material, contact between the contained fuel and the metal is avoided, and elution of metal ions into the fuel is prevented.
JP 2005-5155 A JP 2005-38803 A

  An object of the present invention is to provide a liquid fuel for a fuel cell, a fuel cartridge for a fuel cell, and a fuel cell capable of achieving improvement in long-term operation performance and suppression of fuel permeation to the cathode.

The liquid fuel for a fuel cell according to the present invention is a liquid fuel for a fuel cell containing a fuel component and a cationic impurity (however, excluding H ⁺ ), and the content of the cationic impurity is 1 × 10 6. ^-7 ion equivalent / L or more and 6 × 10 ^-6 ion equivalent / L or less.

  Examples of the fuel component include a compound having an alcoholic hydroxyl group and / or an aldehyde group in the molecule, or an aqueous solution of the compound.

  Examples of the cationic impurities include at least one cation selected from alkali metal ions, alkaline earth metal ions, transition metal ions, group III metal ions, group IV metal ions, sulfonium ions, and ammonium ions. Can be mentioned.

A fuel cartridge for a fuel cell according to the present invention is a fuel cartridge for a fuel cell comprising a container having a liquid fuel outlet and a liquid fuel accommodated in the container,
The content of cationic impurities (excluding H ⁺ ) in the liquid fuel at the liquid fuel outlet is 1 × 10 ⁻⁷ ion equivalent / L or more and 6 × 10 ⁻⁶ ion equivalent / L or less. It is characterized by.

  In the fuel cartridge for a fuel cell, a cation adsorbent can be disposed in a portion of the container or the liquid fuel outlet that contacts the liquid fuel. Examples of the cation adsorbent include at least one selected from cation exchange resins and cation exchange ceramics.

  In addition, a layer that suppresses permeation of the fuel into the cartridge can be formed at the interface portion of the container that contacts the liquid fuel.

A fuel cell according to the present invention includes a container having a liquid fuel outlet, a fuel cartridge including liquid fuel accommodated in the container, and a fuel cell electromotive unit to which the liquid fuel outlet of the fuel cartridge is connected. A fuel cell comprising:
The content of cationic impurities (excluding H ⁺ ) in the liquid fuel at the liquid fuel outlet is 1 × 10 ⁻⁷ ion equivalent / L or more and 6 × 10 ⁻⁶ ion equivalent / L or less. It is characterized by.

  ADVANTAGE OF THE INVENTION According to this invention, the liquid fuel for fuel cells, the fuel cartridge for fuel cells, and a fuel cell which can achieve improvement of long-term driving performance and suppression of fuel permeation to the cathode can be provided.

The present invention has been made in the intensive study of the influence of cationic impurities on cell performance in liquid fuel cells. Cationic impurities accumulate in the membrane electrode assembly (MEA), which is the heart of the fuel cell, and poison the electrolyte, catalyst, electrolyte membrane, etc. in the catalyst layer, so that the fuel cell usage time (cumulative time) As the process progresses, there is a problem that the fuel cell performance is degraded and deteriorated. The present inventors have found that when the accumulated amount is about 10% or more of the ion exchange amount of the electrolyte used in the MEA (the total of the electrolyte membrane and the electrolyte in the electrode), rapid deterioration is observed. In order to protect the fuel cell electromotive part from performance deterioration due to cationic impurities, the total amount of cationic impurities at the liquid fuel outlet part of the fuel cartridge should be 6 × 10 ⁻⁶ ion equivalent / L or less. Is desirable. When the concentration exceeds 6 × 10 ⁻⁶ ion equivalent / L (normative), when the fuel cell is driven, the resistance of the electrolyte increases and the deterioration and deterioration of the performance of the fuel cell due to the failure of the catalytic reaction increase. The performance cannot be maintained for a long time.

Since this cationic impurity is accumulated in the MEA even at a low concentration, it should be considered that it is preferable that the cationic impurity is not present at all. Therefore, the present inventors have considered that the cationic impurity has fuel permeation to the cathode (particularly methanol crossover). It is found for the first time that it has the effect of suppressing the above-mentioned, and the amount thereof is set to 1 × 10 ⁻⁷ ion equivalent / L (specified) or more and 6 × 10 ⁻⁶ ion equivalent / L (specified) or less, thereby improving long-term operation performance It was found that the fuel can be improved and the fuel permeation to the cathode can be suppressed. A more preferable range of the total amount of the cationic impurities at the liquid fuel outlet of the fuel cartridge is 4 × 10 ⁻⁷ ion equivalent / L (specified) or more and 3 × 10 ⁻⁶ ion equivalent / L (specified) or less.

  Examples of the cationic impurities include alkali metal ions, alkaline earth metal ions, transition metal ions, group III metal ions, group IV metal ions, sulfonium ions, ammonium ions, and the like. The type of cation contained in the liquid fuel may be one type or two or more types. Among these, from the viewpoint of enhancing the fuel permeation suppressing effect, Na ion, K ion, Ca ion, Fe ion, Ni ion, Cr ion, Mn ion, Cu ion, Zn ion, Co ion, Mg ion, Sn ion, Pb ion, It is desirable that at least one cation selected from the group consisting of Al ions and ammonium ions is contained.

The fuel cartridge includes a container having a liquid fuel outlet and a liquid fuel accommodated in the container. The fuel cartridge may be detachable from the fuel cell electromotive unit and replaceable, or may be fixed to the fuel cell electromotive unit and replenished with liquid fuel. In order to set the total amount of cationic impurities at the liquid fuel outlet to 1 × 10 ⁻⁷ ion equivalent / L (normal) or more and 6 × 10 ⁻⁶ ion equivalent / L (normal) or less, for example, It is conceivable to use a liquid fuel whose total amount is within the above range. For example, the total amount of cationic impurities in the liquid fuel can be controlled within the above range by purification using an ion exchange resin or the like.

  It is desirable that the cationic impurity concentration of the liquid fuel is set in the above range in advance, and the container of the fuel cartridge is formed from a polymer or metal that does not dissolve in the fuel.

  Examples of such polymers include polyethylene, polypropylene, Teflon (registered trademark), PFA, polycarbonate, polyetheretherketone (PEEK), polysulfone, polystyrene, polymethylpentene, and epoxy resin.

  On the other hand, examples of the metal include stainless steel, molybdenum, and titanium. In addition, even a metal that can be gradually dissolved in fuel or the like can be used by providing a metal container protective layer (barrier layer) that does not dissolve inside the container. Examples of the metal container protective layer include noble metals, oxides (for example, oxides of at least one element selected from the group consisting of Ti, Si, and Zr), polymers, diamond-like carbon (DLC), and the like. It is not limited.

  Even in the above-mentioned polymer, there is a possibility that a synthesis catalyst or an additive in the polymer is eluted into the liquid fuel. Moreover, in a metal container, since a cationic impurity will produce | generate by reaction with a fuel, dissolved oxygen, etc., it is desirable to form protective layers, such as a polymer, on the inner wall of a metal container. The protective layer can be formed by, for example, a sputtering method, a CVD method, a coating method, or the like.

  In the container, in order to prevent elution of the ionic component from the protective layer and the polymer, it is preferable to form a barrier layer that suppresses the penetration of the liquid fuel at least at the interface portion in contact with the liquid fuel. The barrier layer is formed by, for example, a sputtering method, a CVD method, a coating method, or the like. The material of the specific barrier layer is selected from an oxide (for example, an oxide and composite oxide of at least one element selected from the group consisting of Ti, Zr and Si, a group consisting of Ti, Zr and Si). And at least one element selected from the group consisting of Mo, P and W), diamond-like carbon (DLC), and the like, but are not limited thereto.

  If a cationic impurity adsorbent is built in the fuel cartridge, the cationic impurity can be removed by the adsorbent even if it is eluted from the fuel cartridge. The total amount can be maintained at a specified value. Examples of adsorbents for cationic impurities include cation exchange resins and cation exchange ceramics. The kind of adsorbent to be used can be one kind or two or more kinds. The cation exchange capacity incorporated in the cartridge may be an ion exchange amount that is equal to or greater than the total amount of the cationic impurities already contained in the fuel and the expected elution amount from the fuel cartridge. Furthermore, it is better if it is more than 3 times the total amount of impurities. The adsorbent may be placed anywhere as long as it is in contact with the liquid fuel, and the shape is not particular. Specific examples include, but are not limited to, a case where it is arranged as a filter at the liquid fuel outlet portion of the cartridge, a case where it is arranged as a granular material inside the cartridge, and a case where it is attached inside the cartridge. Any polymer can be used as the cation exchange resin as long as it has at least one functional group selected from the group consisting of a sulfonic acid group, a carboxyl group, and a phosphoric acid group (phosphonic acid group) and is insoluble in liquid fuel. . Specific examples include, but are not limited to, sulfonated styrene-divinylbenzene copolymer resins. As the cation exchange ceramic, it is preferable to use a hardly soluble salt of hydrogen phosphate and / or hydrogen sulfate. Specific examples include, but are not limited to, zirconium hydrogen phosphate.

Even in the case of liquid fuel having a cationic impurity concentration exceeding 6 × 10 ⁻⁶ ion equivalent / L, the cationic impurities are removed by the adsorbent in the fuel cartridge, and the total amount of cationic impurities at the liquid fuel outlet is It can be used if it is 1 × 10 ⁻⁷ ion equivalent / L (normative) or more and 6 × 10 ⁻⁶ ion equivalent / L (normative) or less.

  When the container of the fuel cartridge is formed of a polymer, it is desirable to provide a further protective layer in order to prevent evaporation of the liquid fuel from the cartridge in addition to the protective layer. This protective layer is obtained by forming a thin film of metal or DLC by vapor deposition or sputtering at a position where the liquid in the fuel cartridge is stored and not in contact with the liquid fuel. Specific examples include aluminum and DLC, but are not limited thereto.

  As the fuel component, it is desirable to use a compound having an alcoholic hydroxyl group and / or an aldehyde group in the molecule or an aqueous solution of the compound. Specific examples of the compound include, but are not limited to, methanol, ethanol, 2-propanol, formic acid and the like. Further, the compound content in the fuel component is preferably 30% by weight or more and 100% by weight or less, and more preferably 60% by weight or more and 100% by weight or less. When the compound content in the fuel component is less than 30% by weight, the fuel tank becomes too large, and it is difficult to reduce the size. The content of water or the like as the other component of the fuel can be appropriately determined according to the amount of such a compound.

  An embodiment of a fuel cell according to the present invention is shown in FIGS.

  FIG. 1 is a schematic diagram showing a configuration example of an active liquid fuel cell according to a first embodiment of the present invention, FIG. 2 is a schematic cross-sectional view of the fuel cartridge of FIG. 1, and FIG. It is a schematic diagram which shows the structural example of the passive liquid fuel cell which concerns on 2 embodiment.

  The fuel cell shown in FIG. 1 includes a fuel cell electromotive unit 1 and a fuel cartridge 2 connected to the fuel cell electromotive unit 1. The fuel cell electromotive unit 1 includes a stack 3 including at least one set of membrane electrode assemblies (MEA), a liquid fuel tank 4, fuel pumps 5 and 23, a concentration sensor 22, and an auxiliary device 6. The membrane electrode assembly (MEA) includes an electrolyte membrane, a cathode formed on one surface of the electrolyte membrane, and an anode formed on the other surface of the electrolyte membrane. As the electrolyte membrane, for example, a proton conductive membrane such as a perfluorosulfonic acid membrane can be used. The anode (fuel electrode) includes an anode catalyst layer and an anode diffusion layer (for example, carbon paper). For the anode catalyst, for example, a Pt—Ru-based catalyst can be used. The cathode (oxidant electrode) includes a cathode catalyst layer and a cathode diffusion layer (for example, carbon paper). For the cathode catalyst, for example, a Pt-based catalyst can be used.

  The stack 3 further includes a separator having a fuel flow path disposed on the anode side of the MEA and a separator having an oxidant flow path disposed on the cathode side of the MEA.

A liquid fuel supply path 7 and a liquid fuel discharge path 8 are provided between the liquid fuel tank 4 and the stack 3. The liquid fuel supply path 7 is for supplying liquid fuel to the anode of the stack 3, and the liquid fuel discharge path 8 is for recovering the liquid fuel discharged from the anode of the stack 3 to the liquid fuel tank 4. It is. The auxiliary machine 6 includes an air pump (not shown) for supplying air to the cathode of the MEA, and a condenser (cooler) for cooling the air discharged from the cathode and the exhaust gas of the anode. An air supply path 10 and an air discharge path 11 are provided between the auxiliary machine 6 and the stack 3. Further, a condensed water recovery path 9 and a CO ₂ exhaust gas path 12 are provided between the liquid fuel tank 4 and the auxiliary machine 6. The air supply path 10 is for supplying the air sent out by the air pump to the cathode of the stack 3, and the air discharge path 11 is for returning the air discharged from the cathode to the condenser. The air discharged from the cathode is cooled by the condenser to condense moisture, and is recovered in the liquid fuel tank 4 through the condensed water recovery path 9, and the gaseous component is discharged through the exhaust gas pipe 24. Further, the exhaust gas generated at the anode is cooled by the aggregator of the auxiliary machine 6 through the CO ₂ exhaust gas passage 12 and separated into gas and liquid, and then CO ₂ is discharged to the outside through the exhaust gas pipe 24.

  As shown in FIG. 2, the liquid fuel cartridge 2 includes a container 13, a connector 14 formed in the container 13, a filter or adsorbent 15 disposed in the connector 14, and one end disposed at the bottom of the container 13. And the pipe 16 disposed at the other end in the liquid fuel outlet portion 14a of the connector 14. The pipe 16 is for efficiently guiding the liquid fuel to the liquid fuel outlet 14a when the amount of the liquid fuel in the container 13 decreases. Further, a barrier layer 17 may be formed on a portion (for example, the inner wall) of the container 13 that comes into contact with the liquid fuel.

  The connector 14 has a detachable structure and is connected to the liquid fuel tank 4 via the fuel pump 5. Therefore, the liquid fuel cartridge 2 can be replaced. If the connector 14 is not detachable and it is difficult to replace the liquid fuel cartridge 2, it is preferable to provide a supply port in the container 13 and replenish the liquid fuel from the supply port.

  The passive liquid fuel cell shown in FIG. 3 has the same configuration as the active liquid fuel cell shown in FIGS. 1 and 2 described above, except that the method for supplying fuel to the anode is different.

  The planar stack 18 to which membrane electrode assemblies (MEAs) are connected in parallel is disposed on both sides of the liquid fuel tank 19. Between the planar stack 18 and the liquid fuel tank 19, a layer 20 for controlling the supply amount of the liquid fuel (for example, a liquid diffusion control film or a gas-liquid separation film that selectively permeates the vaporized component) 20 is disposed. Yes.

  A detachable connector 14 of the liquid fuel cartridge 2 is connected to a liquid fuel tank 19 via a fuel pump 21.

[Example]
Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
Cationic impurities in 50 g (grade EL) of 99.6% methanol were analyzed by ICP-MS (measuring device; manufactured by SII Nanotechnology, SPQ-9000). As a result, Na, K, Ca, Mg, Ni, Fe, The total amount of Zn, Al, etc. was 4 × 10 ⁻⁷ normal (ion equivalent / liter). The total amount of cations in pure water was 1 × 10 ⁻⁷ normal (ion equivalent / liter) or less. This methanol is diluted with pure water to make a 1 mol / l solution, and a nitrate of Na is added to the solution so that the total amount of cationic impurities is 2.2 × 10 ⁻⁶ normal (about 50 ppb). Got fuel. The obtained liquid fuel was filled into a polyethylene fuel cartridge, and a fuel cell was evaluated under the conditions described later with a single cell having an electrode area of 12 cm ² .

(Examples 2-6 and 10-19)
A fuel cell liquid was prepared in the same manner as described in Example 1, except that metal nitrates shown in Table 1 below were added in place of Na nitrate so that the cationic impurity concentration would be the value shown in Table 1 below. Got fuel.

(Examples 7 to 8)
Al nitrate was added to a 3 molar aqueous solution of formic acid so that the cationic impurity concentration would be the value shown in Table 1 below to obtain a liquid fuel for a fuel cell.

Example 9
Al nitrate was added to a 1-mol aqueous solution of 2-propanol so that the cationic impurity concentration was a value shown in Table 1 below, to obtain a liquid fuel for a fuel cell.

(Example 20)
A liquid fuel for a fuel cell was obtained in the same manner as described in Example 1, except that ammonium nitrate was added in place of Na nitrate so that the cationic impurity concentration was a value shown in Table 1 below.

(Comparative Examples 1-7)
A liquid fuel for a fuel cell was obtained in the same manner as in Example 1 except that the types and concentrations of the cationic impurities were set as shown in Table 2 below.

(Comparative Examples 8 and 9)
A liquid fuel for a fuel cell was obtained in the same manner as in Example 7 except that the types and concentrations of the cationic impurities were set as shown in Table 2 below.

(Comparative Example 10)
A liquid fuel for a fuel cell was obtained in the same manner as in Example 9 except that the types and concentrations of the cationic impurities were set as shown in Table 2 below.

(Comparative Example 11)
A liquid fuel for a fuel cell was obtained in the same manner as in Example 1 except that no cationic species was added.

(Example 21) Evaluation of battery performance degradation due to cationic impurities In the MEA used, carbon paper was used for the gas diffusion layer (GDL). The amount of platinum loaded on the cathode was 2.0 mg / cm ² , and the amount of catalyst loaded on the anode was 3.8 mg / cm ² . The flow path of the single cell was a serpentine type. The electrode area was 12 cm ² . The operating conditions of the fuel cell were 70 ° C., an air flow rate of 120 ml / min, a fuel flow rate of 0.8 ml / min, and a change in voltage with time at a current density of 150 mA / cm ² was observed. The results are shown in Tables 1 and 2 as deterioration rates. However, deterioration rate = voltage after 500 hours / initial voltage. In addition, as shown in FIG. 4, the operation was expressed as an elapsed time by accumulating the drive time, assuming that the 10-hour operation and the 14-hour stop were 1 cycle / day.

The results of Tables 1 and 2 will be described with reference to FIG. As shown in FIG. 5, when the standard fuel was used (Comparative Example 11), the deterioration rate of the long-term performance was 4% due to deterioration of the MEA itself (deterioration of the catalyst etc.). In the fuel cells of Comparative Examples 1 to 10 where the cationic impurity concentration exceeds 6 × 10 ⁻⁶ ion equivalent / L, deterioration due to the cationic impurities occurs remarkably in addition to deterioration of the MEA itself, so long-term performance deterioration The rate increased to 9-29%.

On the other hand, in the fuel cells of Examples 1 to 20 having a cationic impurity concentration of 1 × 10 ⁻⁷ ion equivalent / L or more and 6 × 10 ⁻⁶ ion equivalent / L or less, Comparative Example 11 using a standard fuel was used. The degradation rate of long-term performance almost equivalent to Among them, Examples 1, 2, 3, ^6, 10, 15, and 17 having a cationic impurity concentration of 4 × 10 ⁻⁷ ion equivalent / L (normal) or more and 3 × 10 ⁻⁶ ion equivalent / L (normal) or less. The deterioration rate of 18 was small.

(Example 22)
Commercially available nafion 117 (electrolyte membrane) is boiled with pure water for 1 hour, boiled with 3% hydrogen peroxide solution for 1 hour, then boiled with 1M sulfuric acid for 1 hour and further with pure water for 1 hour, and then neutralized with pure water. After washing until nafion 117 was stored in pure water. The effect of cations on the pretreated nafion 117 was examined.

And an aqueous solution of Al ³⁺ comprises 2.8 × 10 ^-6 N, was prepared and an aqueous solution containing Al ³⁺ 11.1 × 10 ^-6 N, was dipped nafion117 pretreated for 4 hours, the film of pure Washed with water. The methanol permeability and membrane resistance of these membranes were measured by the following methods.

  The membrane resistance was determined by the direct current method using the measurement cell shown in FIG. A standard electrode (SCE) 32 and a Pt electrode 33 inserted in a Luggin strip 31 are immersed in the electrolytic solution (1M sulfuric acid aqueous solution) in the glass cell 30. Further, the nafion 117 film as the sample 34 is disposed between the Lugin strips 31. As a power source, ABC15-7DM manufactured by Toyo Technica was used, and CDM-2000D was used as a digital multimeter. The measurement conditions were room temperature, air, applied voltage of 15 V, and current of 1 A.

The methanol permeability was measured using the apparatus shown in FIG. During the measurement, 25 ^° C. constant temperature water 35 was circulated through the apparatus. The tanks 37 and 38 through the nafion 117 membrane as the sample 36 were filled with 3M aqueous methanol solution and pure water, and 1 μL of the pure water tank solution was sampled every 4 minutes to measure the methanol concentration. For the measurement, gas chromatography (GC-14A, manufactured by Shimadzu Corporation) was used.

The measurement results are shown in Table 3 with values normalized by the value of nafion 117 (pure water).

From the results in Table 3, it was found that when the Al ³⁺ concentration is 2.8 × 10 ⁻⁶ N, the membrane resistance hardly changes, but the methanol permeability can be suppressed lower than that of pure water. It was also found that when the Al ³⁺ concentration is 11.1 × 10 ⁻⁶ N, the methanol permeability can be further reduced, but the film resistance is increased.

After the deterioration experiment performed in Example 21, the fuel of Example 2 having a cationic impurity concentration of 2.8 × 10 ⁻⁶ N and Example 18 having a cationic impurity concentration of 0.4 × 10 ⁻⁶ N The mass balance of the fuel of Comparative Example 2 having a cationic impurity concentration of 11.1 × 10 ⁻⁶ N and the fuel of Comparative Example 11 having a cationic impurity concentration of less than 1 × 10 ⁻⁷ N were measured, and methanol cross was measured. The over-rate (the amount of methanol determined from the amount of electricity used divided by the amount of methanol used and the value obtained multiplied by 100) was calculated, and the results are shown in Table 4 below.

As is apparent from Table 4, Example 2 having a cationic impurity concentration of 2.8 × 10 ⁻⁶ N, Example 18 having a cationic impurity concentration of 0.4 × 10 ⁻⁶ N, and the cationic impurity concentration In Comparative Example 2 with a 11.1 × 10 ⁻⁶ N, the methanol crossover rate could be reduced as compared with Comparative Example 11 with a cationic impurity concentration of less than 1 × 10 ⁻⁷ N.

From the above results, by setting the cationic impurity concentration to 1 × 10 ⁻⁷ ion equivalent / L or more and 6 × 10 ⁻⁶ ion equivalent / L or less, long-term performance deterioration can be suppressed, and methanol crossover It became clear that it can be suppressed.

(Example 23)
1 g of cation exchange resin with an ion exchange capacity of about 5 meq / g is placed in a container (internal volume of 100 ml) of a fuel cartridge, and 5% methanol aqueous solution containing 100 × 10 ⁻⁶ normal of cation impurities (Al ³⁺ ) is added. After standing for a period of time, the concentration of the cationic impurities in the liquid fuel discharged from the liquid fuel outlet of the connector was determined to be 5 × 10 ^{−6 normal} concentration. When the long-term power generation performance was evaluated in the same manner as in Example 5 using the fuel of Example 23, results almost the same as in Example 5 were obtained.

(Comparative Example 12)
The change in concentration was measured in the same manner as in Example 23, except that no cation exchange resin was placed in the container of the cartridge. There was no change in the concentration of cationic impurities.

(Example 24)
A SiO _x protective layer having a thickness of 100 nm was formed on the inner wall of the polyethylene fuel cartridge container by CVD. Methanol (grade EL) was placed in this fuel cartridge, and the cartridge was closed and stored at a temperature of 40 ° C. for 1 week. Then, the amount of metal cations was measured by ICP-MS, and the total amount was hardly increased. Moreover, the weight loss before and after storage was measured. The weight loss was 0.2%.

(Example 25)
An Al film having a thickness of 500 nm was formed on the outer wall of a polyethylene fuel cartridge by sputtering. The cartridge was stored for 1 week at a temperature of 40 ° C. with the cartridge closed. The change in weight before and after storage was about 0.1%.

(Comparative Example 13)
Methanol (EL grade) was put into a polyethylene fuel cartridge, the weight was measured, and the cartridge was closed and stored at a temperature of 40 ° C. for 1 week, and then the amount of metal cation was measured by ICP-MS. The total amount was 9 × 10 ^-6 regulations, increased from the state before storage. The weight change before and after storage was about 0.5%.

  As described above in detail, according to the present invention, by providing a fuel cartridge for a fuel cell that defines the concentration of cationic impurities in the fuel supplied to the liquid fuel cell, deterioration of the fuel cell is greatly suppressed, The battery can be used for a long time, and its industrial value is tremendous.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The schematic diagram which shows the structural example of the fuel cell which concerns on the 1st Embodiment of this invention. FIG. 2 is a schematic cross-sectional view of the fuel cartridge of FIG. 1. The schematic diagram which shows the structural example of the fuel cell which concerns on the 2nd Embodiment of this invention. The schematic diagram for demonstrating the fuel cell power generation test done in the Example. The characteristic view for demonstrating the cause of performance degradation of the fuel cell of Comparative Examples 1-11. The schematic diagram which shows the resistance measuring device used by the film | membrane resistance measurement test of an Example. The schematic diagram which shows the measuring device used in the methanol crossover test of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell electromotive part, 2 ... Fuel cartridge, 3 ... Stack, 4,19 ... Liquid fuel tank, 5, 21, 23 ... Fuel pump, 6 ... Auxiliary machine, 7 ... Liquid fuel supply path, 8 ... Liquid fuel discharge path, 9 ... condensed water recovery passage, 10 ... air supply passage, 11 ... air discharge passage, 12 ... CO ₂ exhaust gas passage, 13 ... container, 14 ... connector, 14a ... liquid fuel outlet section, 15 ... filter or suction 16 ... pipe, 17 ... barrier layer, 18 ... planar stack, 20 ... fuel supply amount control layer (for example, gas-liquid separation membrane), 22 ... concentration sensor, 24 ... exhaust gas pipe.

Claims (5)

A liquid fuel for a fuel cell containing a fuel component and a cationic impurity (excluding H ⁺ ), wherein the content of the cationic impurity is 1 × 10 ⁻⁷ ion equivalent / L or more, 6 × 10 ^-6 ion equivalent / L or less, a liquid fuel for fuel cells.   2. The liquid fuel for a fuel cell according to claim 1, wherein the fuel component is a compound having an alcoholic hydroxyl group and / or an aldehyde group in a molecule or an aqueous solution of the compound.   The cationic impurity is at least one cation selected from alkali metal ions, alkaline earth metal ions, transition metal ions, group III metal ions, group IV metal ions, sulfonium ions, and ammonium ions. The liquid fuel for a fuel cell according to claim 1 or 2, characterized in that: A fuel cartridge for a fuel cell comprising a container having a liquid fuel outlet and a liquid fuel accommodated in the container,
The content of cationic impurities (excluding H ⁺ ) in the liquid fuel at the liquid fuel outlet is 1 × 10 ⁻⁷ ion equivalent / L or more and 6 × 10 ⁻⁶ ion equivalent / L or less. A fuel cartridge for a fuel cell. A fuel cell comprising: a container having a liquid fuel outlet portion; a fuel cartridge having liquid fuel contained in the container; and a fuel cell electromotive portion to which the liquid fuel outlet portion of the fuel cartridge is connected. ,
The content of cationic impurities (excluding H ⁺ ) in the liquid fuel at the liquid fuel outlet is 1 × 10 ⁻⁷ ion equivalent / L or more and 6 × 10 ⁻⁶ ion equivalent / L or less. A fuel cell.

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