Polymer electrolyte fuel cells and water electrolysis devices

Abstract

The present invention provides a polymer electrolyte fuel cell and a water electrolysis device containing a novel deterioration inhibitor that is inexpensive and highly effective even in a smaller amount. [Solution] The solid polymer fuel cell and water electrolysis device each include a membrane-electrode-gas diffusion layer assembly (MEGA) in which catalyst layers are bonded to both sides of a solid polymer electrolyte membrane and gas diffusion layers are disposed on the outer sides of the catalyst layers, and a degradation inhibitor added to any part of the MEGA. The degradation inhibitor includes a complex in which a ligand is coordinated to an Fe ion. The ligand includes 1,10-phenanthroline-5,6-dione and / or a derivative thereof.

Description

[Technical Field]

[0001] The present invention relates to a polymer electrolyte fuel cell and a water electrolysis device, and more particularly to a polymer electrolyte fuel cell and a water electrolysis device containing an additive that has the effect of suppressing degradation of a solid polymer electrolyte. [Background technology]

[0002] A polymer electrolyte fuel cell comprises a membrane electrode assembly (MEA) in which catalyst layers are bonded to both sides of an electrolyte membrane. A gas diffusion layer is usually arranged on the outside of the catalyst layer. A laminate of the MEA and the gas diffusion layer is also called a membrane-electrode-gas diffusion layer assembly (MEGA). Furthermore, a current collector (separator) with a gas flow path is arranged on the outside of the gas diffusion layer. A polymer electrolyte fuel cell usually has a structure (stack) in which multiple unit cells each consisting of such a MEGA and a current collector are stacked. A polymer electrolyte membrane (PEM) water electrolysis device has a similar structure to a polymer electrolyte fuel cell, although its usage differs from that of a polymer electrolyte fuel cell.

[0003] The electrolyte contained in MEGA is said to be attacked and deteriorated by radicals generated directly by the direct reaction or electrochemical reaction of oxygen and hydrogen, or by radicals generated via hydrogen peroxide. In solid polymer fuel cells and PEM water electrolysis systems, radical attack is known to increase the resistance of the electrolyte membrane, increase cross-leakage, and shorten the lifespan due to thinning. Furthermore, degradation products generated by radical attack can poison the catalyst, potentially reducing electrolysis and cell performance.

[0004] Therefore, various proposals have been made in the past to solve this problem. For example, Patent Document 1 discloses a solid polymer electrolyte containing tungsten oxide formed by a hydrolysis method. The same document states: (A) Tungsten oxide functions as a catalyst for decomposing hydrogen peroxide, and (B) By using the hydrolysis method, nanometer-sized tungsten oxide can be dispersed almost uniformly throughout the solid polymer electrolyte. is stated.

[0005] Patent Document 2 discloses a solid polymer electrolyte membrane obtained by applying a liquid composition containing a sulfonic acid group-containing fluorocarbon polymer and cerium oxide onto a substrate using a die coater and drying the applied composition. The document also describes that cerium oxide has the effect of suppressing the degradation of polymers caused by hydrogen peroxide or peroxide radicals.

[0006] Patent Document 3 states: (a) An electrolyte membrane obtained by mixing bathophenanthroline, Ce(NO3)3·6H2O, and a perfluorosulfonic acid (PFSA) ionomer dispersion and casting the mixture. (b) an electrolyte membrane obtained by mixing 1,10-phenanthroline-5-amine, MnO2, and a PFSA ionomer dispersion and casting the mixture; and (c) An electrolyte membrane obtained by mixing 1,10-phenanthroline, MnO2, and a PFSA ionomer dispersion and casting the mixture. has been disclosed.

[0007] The same document states: (A) By such a method, a proton-conducting composite polymer electrolyte containing a metal-ligand complex can be obtained; (B) An electrolyte membrane containing a metal-ligand complex consisting of (Ce)(bathophenanthroline) or (Mn)(1,10-phenanthroline-5-amino) exhibits higher performance than a Nafion® 875 membrane containing no degradation inhibitor; and (C) An electrolyte membrane containing a metal-ligand complex consisting of (Mn)(1,10-phenanthroline) exhibits lower performance than a Nafion® 875 membrane containing no degradation inhibitor. is stated.

[0008] To improve the durability of polymer electrolyte fuel cells, it is important to suppress the degradation of the electrolyte membrane, and various degradation inhibitors have been proposed. Of these, tungsten oxide and cerium oxide have the effect of suppressing deterioration of the electrolyte membrane, as described in Patent Documents 1 and 2. However, when tungsten oxide is added to the electrolyte membrane, components eluted from the tungsten oxide may migrate to the cathode side and poison the electrode catalyst on the cathode side.

[0009] Furthermore, when the degradation inhibitor is a cationic material, the cationic components of the degradation inhibitor may undergo ion exchange with protons of the acid groups of the electrolyte membrane or the catalyst layer ionomer, resulting in a decrease in the proton conductivity of the electrolyte. A decrease in proton conductivity can lead to a decrease in fuel cell performance. In particular, when cerium oxide is added to the electrolyte membrane, cerium ions may be eluted from the cerium oxide. Because cerium ions have a large valence, a significant decrease in the conductivity of the electrolyte membrane occurs when they are ion exchanged with protons of the acid groups of the electrolyte membrane. On the other hand, as described in Patent Document 3, it is known that certain metal-ligand complexes have the effect of improving the durability of fuel cells. However, in order to suppress the deterioration of the electrolyte membrane, a deterioration inhibitor that is highly effective in smaller amounts is desired. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 4326271 [Patent Document 2] International Publication No. 2020 / 116645 [Patent Document 3] U.S. Patent No. 09172107 Summary of the Invention [Problem to be solved by the invention]

[0011] An object of the present invention is to provide a polymer electrolyte fuel cell and a water electrolysis device containing a novel deterioration inhibitor that is highly effective in smaller amounts. [Means for solving the problem]

[0012] In order to solve the above problems, the polymer electrolyte fuel cell according to the present invention comprises: a membrane-electrode-gas diffusion layer assembly (MEGA) in which catalyst layers are bonded to both sides of a solid polymer electrolyte membrane and gas diffusion layers are disposed on the outer sides of the catalyst layers; A deterioration inhibitor added to any part of the MEGA; Equipped with The deterioration inhibitor includes a complex in which a ligand is coordinated to an Fe ion, The ligand comprises 1,10-phenanthroline-5,6-dione and / or a derivative thereof.

[0013] The water electrolysis device according to the present invention comprises: a membrane-electrode-gas diffusion layer assembly (MEGA) in which catalyst layers are bonded to both sides of a solid polymer electrolyte membrane and gas diffusion layers are disposed on the outer sides of the catalyst layers; A deterioration inhibitor added to any part of the MEGA; Equipped with The deterioration inhibitor includes a complex in which a ligand is coordinated to an Fe ion, The ligand comprises 1,10-phenanthroline-5,6-dione and / or a derivative thereof. [Effects of the Invention]

[0014] Complexes in which certain phenanthroline-based ligands are coordinated to Fe ions have the ability to eliminate substances that cause membrane degradation (H2O2, ·OH, ·H). This is thought to be because complexes in which certain phenanthroline-based ligands are coordinated to Fe ions have an oxidation-reduction potential of 0.75 V (vs. RHE) or higher and 1.8 V (vs. RHE) or lower. Complexes with such oxidation-reduction potentials are capable of undergoing electron transfer (redox) reactions with substances that cause membrane degradation, and it is thought that the electron transfer reaction eliminates the substances that cause membrane degradation. Therefore, when a small amount of such a complex is added as a deterioration inhibitor to any part of the MEGA, the durability of the polymer electrolyte fuel cell and the water electrolysis device can be improved. [Brief explanation of the drawings]

[0015] [Figure 1] 1 shows the F-emission amounts after durability tests of the cells obtained in Example 1 and Comparative Examples 1 to 3. [Figure 2] 1 shows the F-emission amounts after durability tests of the cells obtained in Example 2 and Comparative Examples 4 to 6. DETAILED DESCRIPTION OF THE INVENTION

[0016] [Configuration 1] a membrane-electrode-gas diffusion layer assembly (MEGA) in which catalyst layers are bonded to both sides of a solid polymer electrolyte membrane and gas diffusion layers are disposed on the outer sides of the catalyst layers; A deterioration inhibitor added to any part of the MEGA; Equipped with The deterioration inhibitor includes a complex in which a ligand is coordinated to an Fe ion, The ligand comprises 1,10-phenanthroline-5,6-dione and / or a derivative thereof. Polymer electrolyte fuel cell.

[0017] [Configuration 2] 2. The polymer electrolyte fuel cell according to claim 1, wherein the content of the deterioration inhibitor is 0.0001 mol % or more and 10.0 mol % or less. however, The "content of deterioration inhibitor" refers to the ratio (=n1 × 100 / n0) of the number of moles of coordinating atoms (n1) contained in the ligand to the number of moles of acid groups (n0) contained in the solid polymer electrolyte membrane and the catalyst layer ionomer.

[0018] [Configuration 3] a membrane-electrode-gas diffusion layer assembly (MEGA) in which catalyst layers are bonded to both sides of a solid polymer electrolyte membrane and gas diffusion layers are disposed on the outer sides of the catalyst layers; A deterioration inhibitor added to any part of the MEGA; Equipped with The deterioration inhibitor includes a complex in which a ligand is coordinated to an Fe ion, The ligand comprises 1,10-phenanthroline-5,6-dione and / or a derivative thereof. Water electrolysis equipment.

[0019] [Configuration 4] 4. The water electrolysis apparatus according to claim 3, wherein the content of the deterioration inhibitor is 0.0001 mol % or more and 10.0 mol % or less. however, The "content of deterioration inhibitor" refers to the ratio (=n1 × 100 / n0) of the number of moles of coordinating atoms (n1) contained in the ligand to the number of moles of acid groups (n0) contained in the solid polymer electrolyte membrane and the catalyst layer ionomer.

[0020] An embodiment of the present invention will be described in detail below. [1. Polymer electrolyte fuel cell] The polymer electrolyte fuel cell according to the present invention comprises: a membrane-electrode-gas diffusion layer assembly (MEGA) in which catalyst layers are bonded to both sides of a solid polymer electrolyte membrane and gas diffusion layers are disposed on the outer sides of the catalyst layers; A deterioration inhibitor added to any part of the MEGA; It is equipped with:

[0021] [1.1. MEGA] The term "membrane electrode assembly (MEA)" refers to an assembly in which an anode catalyst layer is bonded to one surface of an electrolyte membrane and a cathode catalyst layer is bonded to the other surface. "Membrane-electrode-gas diffusion layer assembly (MEGA)" refers to a laminate in which an anode gas diffusion layer and a cathode gas diffusion layer are disposed on the outer sides of the anode catalyst layer and the cathode catalyst layer of an MEA, respectively. In the present invention, the materials of the components constituting the MEGA are not particularly limited, and the most suitable materials can be used depending on the purpose.

[0022] [1.1.1. Electrolyte membrane] Examples of materials for the electrolyte membrane include Nafion (registered trademark), Flemion (registered trademark), Aquivion (registered trademark), and Aciplex (registered trademark).

[0023] [1.1.2. Catalyst layer] The catalyst layer usually comprises a composite of an electrode catalyst and a catalyst layer ionomer. An electrode catalyst usually comprises a carrier and catalyst particles (active species) supported on the surface of the carrier, although the electrode catalyst may also consist of only catalyst particles.

[0024] The material of the catalyst particles is not particularly limited as long as it has hydrogen oxidation reaction activity or oxygen reduction reaction activity. (a) Precious metals (Pt, Au, Ag, Pd, Rh, Ir, Ru, Os), (b) an alloy containing two or more precious metal elements; (c) Alloys containing one or more precious metal elements and one or more base metal elements (e.g., Fe, Co, Ni, Cr, V, Ti, etc.); etc.

[0025] Examples of the carrier material include: (a) solid carbon such as carbon black; (b) Porous carbon such as mesoporous carbon; (c) SnO2, non-stoichiometric titanium oxide (TiO x ) and other conductive metal oxides or composite metal oxides etc.

[0026] Examples of the material for the catalyst layer ionomer include: (a) perfluorocarbon sulfonic acid polymers such as Nafion®, Flemion®, Aciplex®, and Aquivion®; (b) High Oxygen Permeable Ionomer (HOPI) etc.

[0027] Here, the term "highly oxygen-permeable ionomer" refers to a polymer compound containing an acid group and a cyclic structure in its molecular structure. Because the highly oxygen-permeable ionomer contains a cyclic structure in its molecular structure, it has a high oxygen permeability coefficient. Therefore, when this ionomer is used as an ionomer, the oxygen transfer resistance at the interface with the catalyst particle becomes relatively small. In other words, the "highly oxygen-permeable ionomer" refers to an ionomer having an oxygen permeability coefficient higher than that of perfluorocarbon sulfonic acid polymers such as Nafion (registered trademark).

[0028] Examples of highly oxygen-permeable ionomers include: (a) an electrolyte polymer containing a perfluorocarbon unit having an aliphatic ring structure and an acid group unit having a perfluorosulfonic acid in a side chain; (b) an electrolyte polymer containing a perfluorocarbon unit having an aliphatic ring structure and an acid group unit having a perfluoroimide in the side chain; (c) an electrolyte polymer containing a unit in which perfluorosulfonic acid is directly bonded to a perfluorocarbon having an aliphatic ring structure; (See References 1-4). [Reference 1] Japanese Patent Application Laid-Open No. 2003-036856 [Reference 2] International Publication No. 2012 / 088166 [Reference 3] JP 2013-216811 A [Reference 4] JP 2006-152249 A

[0029] [1.1.3. Gas diffusion layer] A gas diffusion layer usually includes a substrate and a water-repellent layer formed on the surface of the substrate. Examples of materials for the substrate include carbon fiber nonwoven fabric, carbon paper, carbon cloth, and porous metal sintered body. The water-repellent layer is usually made of a composite of conductive particles and water-repellent particles.

[0030] [1.2. Deterioration inhibitors] [1.2.1. Materials] In the present invention, the deterioration inhibitor includes a complex in which a ligand is coordinated to an Fe ion. The ligand contains at least 1,10-phenanthroline-5,6-dione and / or a derivative thereof, where the term "derivative" refers to a 1,10-phenanthroline-5,6-dione in which at least one of the 2-, 3-, 4-, 7-, 8-, and 9-positions is substituted with one or more functional groups selected from the group consisting of a hydroxyl group, a nitro group, an amino group, a carboxyl group, a carbonyl group, a methyl group, a methoxy group, a fluoro group, a chloro group, a bromo group, a sulfo group, a nitrile group, and a phenyl group.

[0031] The ligand coordinated to one Fe ion may consist solely of 1,10-phenanthroline-5,6-dione and / or a derivative thereof, or may contain other ligands in addition to this. Furthermore, the deterioration inhibitor may consist solely of complex A containing 1,10-phenanthroline-5,6-dione and / or its derivatives as a ligand, or may be a mixture of complex A and complex B containing neither 1,10-phenanthroline-5,6-dione nor its derivatives as a ligand.

[0032] Other ligands include, for example, (a) 1,10-phenanthroline, (b) Compounds with substituents at positions other than 1-, 2-, 9-, and 10- of 1,10-phenanthroline Examples include: An example of (b) is: 5-methyl-1,10-phenanthroline, 4,7-dimethyl-1,10-phenanthroline, 5,6-dimethyl-1,10-phenanthroline, 5-amino-1,10-phenanthroline, 4,7-dimethoxy-1,10-phenanthroline, 4,7-dihydroxy-1,10-phenanthroline etc.

[0033] [1.2.2. Addition site] In the present invention, the location of the degradation inhibitor is not particularly limited. For example, the degradation inhibitor may be added to any one of the electrolyte membrane, catalyst layer, water-repellent layer, and gas diffusion layer substrate, or may be added to two or more of them.

[0034] [1.2.3. Content] The "content of deterioration inhibitor" refers to the ratio (=n1 × 100 / n0) of the number of moles of coordinating atoms (n1) contained in the ligand to the number of moles of acid groups (n0) contained in the solid polymer electrolyte membrane and catalyst layer ionomer. The term "coordinating atom" refers to an atom contained in a ligand that can be directly bonded to the central atom of a complex.

[0035] If the content of the deterioration inhibitor is too low, it becomes difficult to suppress electrolyte degradation due to radicals. Therefore, the content of the deterioration inhibitor is preferably 0.0001 mol% or more. The content is more preferably 0.001 mol% or more, 0.01 mol% or more, 0.1 mol% or more, or 0.5 mol% or more. On the other hand, adding more than necessary of the degradation inhibitor does not make a difference in the effect and is of no practical benefit. Therefore, the content of the degradation inhibitor is preferably 10.0 mol% or less. The content is more preferably 8.0 mol% or less, 6.0 mol% or less, 4.0 mol% or less, or 2.0 mol% or less.

[0036] [2. Water electrolysis device] The water electrolysis device according to the present invention comprises: a membrane-electrode-gas diffusion layer assembly (MEGA) in which catalyst layers are bonded to both sides of a solid polymer electrolyte membrane and gas diffusion layers are disposed on the outer sides of the catalyst layers; A deterioration inhibitor added to any part of the MEGA; It is equipped with:

[0037] The material of the catalyst particles used in the water electrolysis device is not particularly limited as long as it has hydrogen generation reaction activity or oxygen generation reaction activity. Examples of materials for catalyst particles having hydrogen generation reaction activity include: (a) Precious metals (Pt, Au, Ag, Pd, Rh, Ir, Ru, Os), (b) an alloy containing two or more precious metal elements; (c) Alloys containing one or more precious metal elements and one or more base metal elements (e.g., Fe, Co, Ni, Cr, V, Ti, etc.); etc.

[0038] Examples of materials for catalyst particles having oxygen generating reaction activity include metal oxides, such as iridium oxide, ruthenium oxide, cobalt oxide, nickel oxide, iron oxide, and composite oxides of these.

[0039] Other aspects of the structure of the water electrolysis device are the same as those of the polymer electrolyte fuel cell, and therefore a description thereof will be omitted.

[0040] [3. Manufacturing method of polymer electrolyte fuel cells] The polymer electrolyte fuel cell according to the present invention comprises: (a) adding a degradation inhibitor to at least one of the electrolyte membrane, the catalyst layer, and the gas diffusion layer; (b) Catalyst layers are bonded to both sides of the electrolyte membrane to form an MEA. (c) Gas diffusion layers are placed on both sides of the MEA to form the MEGA. (d) Place separators on both sides of the MEGA. It can be produced by In this case, the method of adding the deterioration inhibitor is not particularly limited, and it is preferable to use the most suitable method depending on the location of addition. In the following description of the addition method, the term "deterioration inhibitor" refers to (a) a complex or (b) a mixture of Fe ions and a ligand.

[0041] The deterioration inhibitor can be added to the electrolyte membrane by, for example, (a) A method of obtaining an electrolyte membrane by casting a solution in which a solid polymer electrolyte and a degradation inhibitor are dispersed; (b) a method of applying a solution containing a degradation inhibitor to the surface of an electrolyte membrane that does not contain a degradation inhibitor; (c) A method in which an electrolyte membrane containing no deterioration inhibitor is immersed in a solution containing the deterioration inhibitor. etc.

[0042] The deterioration inhibitor can be added to the catalyst layer by, for example, (a) A method of applying a catalyst ink containing an electrode catalyst, a catalyst layer ionomer, and a deterioration inhibitor to a substrate surface and drying the applied ink; (b) applying a solution containing a degradation inhibitor to the surface of a catalyst layer that does not contain a degradation inhibitor; (c) A method in which a catalyst layer containing no degradation inhibitor is immersed in a solution containing a degradation inhibitor. etc.

[0043] The deterioration inhibitor can be added to the gas diffusion layer by, for example, (a) A method of applying a water-repellent layer paste containing conductive particles, water-repellent particles, and a deterioration inhibitor to the surface of a substrate and drying the paste; (b) A method of applying a solution containing a degradation inhibitor to the MEA-side surface (surface of the water-repellent layer) of a gas diffusion layer that does not contain a degradation inhibitor; (c) A method in which a gas diffusion layer that does not contain a degradation inhibitor is immersed in a solution containing a degradation inhibitor. etc.

[0044] Furthermore, during the manufacturing process of polymer electrolyte fuel cells, Fe ions may be mixed into the MEGA due to unavoidable circumstances. If Fe ion mixing is anticipated, it is possible to add only a ligand to any part of the MEGA. The ligand added to any part of the MEGA will form a complex with the Fe ions mixed into the MEGA due to unavoidable circumstances. Even such a complex functions as a degradation inhibitor.

[0045] [4. Manufacturing method of water electrolysis device] The water electrolysis device has a structure similar to that of a polymer electrolyte fuel cell, except for the material of the catalyst particles. Therefore, the water electrolysis device can be manufactured by the same method as that of a polymer electrolyte fuel cell. Other aspects of the manufacturing method of the water electrolysis device are the same as those of the polymer electrolyte fuel cell, and therefore will not be described here.

[0046] [5. Effect] Complexes in which certain phenanthroline-based ligands are coordinated to Fe ions have the ability to eliminate substances that cause membrane degradation (H2O2, ·OH, ·H). This is thought to be because complexes in which certain phenanthroline-based ligands are coordinated to Fe ions have an oxidation-reduction potential of 0.75 V (vs. RHE) or higher and 1.8 V (vs. RHE) or lower. Complexes with such oxidation-reduction potentials are capable of undergoing electron transfer (redox) reactions with substances that cause membrane degradation, and it is thought that the electron transfer reaction eliminates the substances that cause membrane degradation. Therefore, when a small amount of such a complex is added as a deterioration inhibitor to any part of the MEGA, the durability of the polymer electrolyte fuel cell and the water electrolysis device can be improved. [Example]

[0047] (Example 1, Comparative Examples 1 to 3) 1. Sample Preparation 1.1. Preparation of electrolyte membrane containing degradation inhibitor As the ionomer solution for forming the electrolyte membrane and the catalyst layer, a Nafion (registered trademark) solution (solid content: 21.5 mass%, Ew: 1000) was used.

[0048] Additives include: (a) None (Comparative Example 1), (b) Ce ions (Comparative Example 2), (c) 1,10-phenanthroline (phen) (Comparative Example 3), or (d) 1,10-phenanthroline-5,6-dione (phen-dione) (Example 1) was used. Table 1 shows the structures, redox species, and redox potentials of various additives.

[0049] [Table 1]

[0050] The ionomer solution and additives were mixed in a sample bottle. The amount of Ce ions added was 4.4 mol% of the amount of sulfonic acid groups in the ionomer. The amount of other additives added was 1.5 mol% of the amount of sulfonic acid groups in the ionomer. This ionomer solution was hand-coated onto a PET film and then dried at 140°C in air to produce an electrolyte membrane with a thickness of approximately 30 μm.

[0051] 1.2. Cell Preparation Platinum-supported carbon was dispersed in an ionomer solution to obtain a catalyst ink. This catalyst ink was applied to a PET film and dried to obtain a catalyst layer. The platinum weight of the catalyst layer was 0.2 mg / cm. 2 It was. The resulting catalyst layers were thermally transferred to both sides of the electrolyte membrane at 140°C to obtain a membrane electrode assembly (MEA). The electrode area of ​​the MEA was 4 cm. 2 The effective electrode area is 3.24 cm 2 Furthermore, the MEA was sandwiched between paper gas diffusion layers (GDLs) with water-repellent layers to form a cell.

[0052] 2. Test Method [2.1. Break-in] The above cell was run-in under the following conditions:

[0053] [Run-in] Cell temperature: 80.0℃ Humidity: Anode 20%RH, Cathode 122%RH, Gas: Anode (H2, 1.0L / min), Cathode (Air, 2.0L / min) Back pressure: 50kPa Measurement conditions: 0.1V (9 minutes) + OCV (1 minute), 6 cycles

[0054] [2.2. Initial power generation performance] The initial power generation performance of the cells after the break-in was evaluated under the following conditions:

[0055] [Power generation performance evaluation] Cell temperature: 80.0℃ Humidity: 80%RH (bubbler temperature 52.9℃) or 30%RH (bubbler temperature 74.6℃) Gas: Anode (H2, 1.0L / min), Cathode (Air, 2.0L / min) Back pressure: 0kPa Measurement conditions: OCV-0.1V-OCV, 0.02V / s, 5 cycles

[0056] 2.3. Durability test After evaluating the initial power generation performance, the cell was subjected to an open circuit voltage (OCV) retention durability test under the following conditions:

[0057] [OCV durability test] Cell temperature: 95.0℃ Humidity: 30% RH at both poles (bubbler temperature is 65°C at both poles) Gas: Anode (H2, 0.3L / min), Cathode (Air, 0.3L / min) Back pressure: 133kPa on both sides Durability: 90 hours Collection of discharged water: Collect water at 24, 48, 72, and 90 hours after the start of the durability test

[0058] [2.4. F - Calculating emissions] After the durability test, the cells were run-in again and then evaluated for power generation performance under the same conditions as above. After a predetermined time has elapsed since the start of the durability test and after the end of the durability test, the water discharged from the cell was collected, and the fluoride ions (F - ) was quantified by ion chromatography. -The amount is integrated and the integrated value is set as "F - emissions."

[0059] [3. Results] FIG. 1 shows the F of the cells obtained in Example 1 and Comparative Examples 1 to 3 after the durability test. - Figure 1 shows the amount of emissions. (1) Comparative Example 1, which does not contain any additives, is the F - The emissions are the highest, and the F - The emission rate is 608 μg / cm 2 reached. This is thought to be due to the fact that Fe ions were mixed into the cell as contaminants from the raw materials, film formation process, cell fabrication process, and piping during performance evaluation. - The increase in emissions is thought to be due to the generation of radical species from hydrogen peroxide due to the influence of Fe ions mixed into the cell, which in turn deteriorated the electrolyte membrane.

[0060] (2) In Comparative Examples 2 and 3 and Example 1, in which additives were added, F was lower than that in Comparative Example 1. - In addition, in Comparative Example 3 and Example 1, the amount of additives contained was about one-third of that in Comparative Example 2, but the amount of F discharged was significantly reduced compared to Comparative Example 1. - The emissions were significantly reduced. In particular, Example 1 showed - The discharge amount was 1 / 4 or less of that in Comparative Example 2.

[0061] (3) The electrolyte membranes obtained in Comparative Example 3 and Example 1 were discolored red immediately after the membrane formation. Furthermore, when the electrolyte membranes obtained in Comparative Example 3 and Example 1 were analyzed after the durability test, iron ions were detected. These results are considered to indicate that the additive and the Fe ions mixed in the cell formed a complex. The complexes of Fe ions with 1,10-phenanthroline or 1,10-phenanthroline-5,6-dione have redox potentials of 0.75 V (vs. SHE) to 1.8 V (vs. SHE). Therefore, it is thought that the complexes react with and eliminate the substances that cause membrane degradation (mainly OH).

[0062] (4) Example 1 is F - The amount of emissions was the lowest. This is thought to be because the complex of Fe ions and 1,10-phenanthroline 5,6-dione has the best compatibility with the causative substance in terms of electron density overlap, and is highly reactive with the causative substance.

[0063] (Example 2, Comparative Examples 4 to 6) 1. Sample Preparation 1.1. Preparation of electrolyte membrane containing degradation inhibitor As the ionomer solution for forming the electrolyte membrane and the catalyst layer, a Nafion (registered trademark) solution (solid content: 21.5 mass%, Ew: 1000) was used.

[0064] Additives include: (a) None (Comparative Example 4), (b) Ce ions (Comparative Example 5), (c) 1,10-phenanthroline (phen) (Comparative Example 6), or (d) 1,10-phenanthroline-5,6-dione (phen-dione) (Example 2) was used.

[0065] The ionomer solution, additive, and iron (II) sulfate were mixed in a sample bottle. The amount of Ce ions added was 4.4 mol% of the amount of sulfonic acid groups in the ionomer. The amounts of 1,10-phenanthroline and 1,10-phenanthroline-5,6-dione added were each 1.5 mol% of the amount of sulfonic acid groups in the ionomer. The amount of iron (II) sulfate (i.e., Fe ions) added was 0.5 mol% of the amount of sulfonic acid groups in the ionomer. This ionomer solution was hand-coated onto a PET film and then dried at 140°C in air to produce an electrolyte membrane with a thickness of approximately 30 μm.

[0066] 1.2. Cell Preparation A cell was fabricated in the same manner as in Example 1.

[0067] 2. Test Method In the same manner as in Example 1, F - The amount of emissions was measured.

[0068] [3. Results] FIG. 2 shows the F of the cells obtained in Example 2 and Comparative Examples 4 to 6 after the durability test. - 2 shows that Example 2 and Comparative Example 6 have a lower F than Comparative Examples 4 and 5. - This is thought to be because, in Comparative Examples 4 and 5, the Fe ions added to the electrolyte membrane function as a radical generation source, whereas in Example 2 and Comparative Example 6, at least a portion of the Fe ions form complexes with ligands, and the complexes function as degradation inhibitors.

[0069] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications are possible within the scope of the gist of the present invention. [Industrial Applicability]

[0070] The polymer electrolyte fuel cell according to the present invention can be used as an in-vehicle power source, a small stationary power generator, and the like. The water electrolysis device according to the present invention can be used as a hydrogen generation device and / or an oxygen generation device.

Claims

1. a membrane-electrode-gas diffusion layer assembly (MEGA) in which catalyst layers are bonded to both sides of a solid polymer electrolyte membrane and gas diffusion layers are disposed on the outer sides of the catalyst layers; A deterioration inhibitor added to any part of the MEGA; Equipped with The deterioration inhibitor includes a complex in which a ligand is coordinated to an Fe ion, The ligand comprises 1,10-phenanthroline-5,6-dione and / or a derivative thereof. Polymer electrolyte fuel cell.

2. 2. The polymer electrolyte fuel cell according to claim 1, wherein the content of the deterioration inhibitor is 0.0001 mol % or more and 10.0 mol % or less. however, The "content of the deterioration inhibitor" refers to the number of moles of acid groups (n 0 ) the number of moles of the ligand atoms contained in the ligand (n 1 ) ratio (= n 1 ×100 / n 0 )

3. a membrane-electrode-gas diffusion layer assembly (MEGA) in which catalyst layers are bonded to both sides of a solid polymer electrolyte membrane and gas diffusion layers are disposed on the outer sides of the catalyst layers; A deterioration inhibitor added to any part of the MEGA; Equipped with The deterioration inhibitor includes a complex in which a ligand is coordinated to an Fe ion, The ligand comprises 1,10-phenanthroline-5,6-dione and / or a derivative thereof. Water electrolysis equipment.

4. The water electrolysis apparatus according to claim 3 , wherein the content of the deterioration inhibitor is 0.0001 mol % or more and 10.0 mol % or less. however, The "content of the deterioration inhibitor" refers to the number of moles of acid groups (n 0 ) the number of moles of the ligand atoms contained in the ligand (n 1 ) ratio (= n 1 ×100 / n 0 )

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