JP4582689B2 - Polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to a polymer electrolyte fuel cell, and more particularly to a seal member that seals between an electrolyte membrane and a separator, and a polymer electrolyte fuel cell in which deterioration of the electrolyte membrane or the like is suppressed.

  A fuel cell that generates electricity by an electrochemical reaction of gas has high power generation efficiency, clean gas discharged, and extremely little influence on the environment. Therefore, in recent years, various uses such as power generation and low-pollution automobile power supplies are expected.

  Among them, the polymer electrolyte fuel cell can be operated at a low temperature of about 80 ° C. and has a large output density. In general, a polymer electrolyte fuel cell uses a polymer film having proton conductivity as an electrolyte. A pair of electrodes serving as a fuel electrode and an oxygen electrode are respectively disposed on both sides of a polymer film (electrolyte film) serving as an electrolyte, thereby forming an electrolyte membrane electrode assembly (MEA). A single cell in which the electrolyte membrane electrode assembly is sandwiched between separators serves as a power generation unit. Then, a fuel gas such as hydrogen or hydrocarbon is supplied to the fuel electrode, and an oxidant gas such as oxygen or air is supplied to the oxygen electrode, and power is generated by an electrochemical reaction at the three-phase interface between the gas, the electrolyte, and the electrode.

Here, the separator performs a function of forming a passage of a reaction gas supplied to each electrode across an adjacent single cell and a function of collecting current from each electrode. For example, when the reaction gas supplied to each electrode is mixed, problems such as reduction in power generation efficiency occur. For this reason, it is necessary to prevent mixing of the reaction gas. On the other hand, the electrolyte membrane has proton conductivity in a state containing water. For this reason, it is necessary to keep the electrolyte membrane in a wet state during battery operation. As described above, in order to prevent the reaction gas from being mixed and to keep the inside of the cell in a wet state, it is important to ensure a sealing property between the electrolyte membrane and the separator. Known methods for sealing between the electrolyte membrane and the separator include, for example, a method in which the electrolyte membrane and the separator are bonded with an adhesive, and a method in which a resin film is interposed between the electrolyte membrane and the separator. It has been. (For example, refer to Patent Documents 1 and 2.)
Japanese Patent Laid-Open No. 2002-117871 JP 2002-352845 A

  Conventionally, the polymer electrolyte fuel cell has a problem that the battery performance is deteriorated by a long-term operation. As a cause of the decrease in battery performance, for example, deterioration of an electrolyte membrane or an electrode can be mentioned. As a result of studying these deteriorations by the present inventor, it has been found that the deterioration of the end portion of the electrode is more remarkable than that of the central portion. In particular, the deterioration was significant at the interface between the electrode and the electrolyte membrane. This is presumably because the gas seal between the electrolyte membrane and the separator is not sufficient, so that the crossover gas from both electrodes is directly combusted in the vicinity of the end of the electrode and is thermally deteriorated due to the temperature rise.

During operation of the polymer electrolyte fuel cell, water is generated from hydrogen and oxygen at the oxygen electrode. On the other hand, depending on the operating conditions, the reduction of oxygen at the oxygen electrode may be stopped by a two-electron reaction, and hydrogen peroxide (H ₂ O ₂ ) may be generated. The produced hydrogen peroxide is dissolved in the produced water. The generated water tends to stay near the end of the electrode. The produced water staying in the vicinity of the end of the electrode evaporates during operation, but hydrogen peroxide has a higher boiling point than water and is likely to remain. Hydrogen peroxide undergoes radical decomposition in the presence of metal ions, for example. This hydrogen peroxide radical attacks the seal member between the electrolyte membrane and the separator. As a result, the seal member is damaged and deteriorates, and the sealing performance is lowered. Hydrogen peroxide radicals also attack electrolyte membranes and electrodes. Thereby, the electrolyte membrane and the electrode are also damaged and deteriorated.

  For the seal member between the electrolyte membrane and the separator, a fluorine resin, a silicon resin, or the like is usually used. Many of the electrolyte membranes are polymer membranes made of a hydrocarbon material or a fluorine material. Conventionally, it has been considered that fluorine-based materials are hardly damaged by peroxides such as hydrogen peroxide. However, as a result of various studies, it has been found that even fluorine-based materials may be damaged by peroxides. In this case, since the C—F bond is decomposed by the peroxide, there is a problem that fluoride ions are eluted and hydrofluoric acid is generated.

  The present invention has been made in view of such a situation, and a solid polymer fuel cell excellent in durability by suppressing deterioration of a sealing member for sealing between an electrolyte membrane and a separator, an electrolyte membrane, and the like. It is an issue to provide.

The polymer electrolyte fuel cell of the present invention comprises an electrolyte membrane having ionic conductivity, a pair of electrodes disposed on both sides of the electrolyte membrane, an electrolyte membrane electrode assembly, and the electrolyte membrane electrode assembly. A separator sandwiched from both sides, and a peroxide decomposition catalyst for decomposing peroxide is disposed on a seal member that seals between the electrolyte membrane and the separator, and the peroxide decomposition catalyst Is a macrocyclic metal complex composed of porphyrin, phthalocyanine or derivatives thereof having Co, Fe, Ti, Al, Ce or the like as a central atom, MnO ₂ , PbO ₂ , RuO ₂ , Sb ₂ O ₃ , Nb ₂ O ₃ , Ta ₂ O ₅ , Nb ₂ O ₅ , WO ₃ , SnO ₂ , Cr ₂ O ₃ , CeO ₂ , La ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ , or HfO ₂ , a sparingly soluble metal oxide, Al A poorly soluble phosphate composed of PO ₄ , TiPO ₄ , FePO ₄ , CrPO ₄ , CePO ₄ , Zr ₃ (PO ₄ ) ₄ , or La ₄ PO ₄ , AlF ₃ , FeF ₃ , CrF ₃ , CeF ₃ , ZrF ₄ Or a sparingly soluble fluoride composed of LaF ₃ , and FeWO ₄ , MnWO ₄ , (Fe, Mn) WO ₄ , CaWO ₄ , CuWO ₄ , Cu ₂ WO ₄ (OH) ₂ , Al ₂ (WO ₄ ) ₃ , SrWO _{4, BaWO 4, Ag 2 WO} 4, ZnWO 4, SnWO 4, or characterized by der Rukoto least one selected from the group consisting of _Ce 2 _{(WO 4)} consists of ₃ sparingly soluble tungsten salt.

The seal member seals a gap between the electrolyte membrane and the separator that occurs in the vicinity of the electrode end. The peroxide decomposition catalyst is disposed on the seal member. Therefore, even if hydrogen peroxide is contained in the generated water staying in the vicinity of the end of the electrode, the hydrogen peroxide is decomposed by the peroxide decomposition catalyst of the seal member. Specifically, as shown in Formula (1), on the surface of the peroxide decomposition catalyst, a so-called catalytic decomposition reaction in which two molecules of hydrogen peroxide collide and decompose into water and oxygen proceeds.
2H ₂ O ₂ → 2H ₂ O + O ₂ (1)
Thus, since hydrogen peroxide generated during operation is decomposed by the peroxide decomposition catalyst before radicalization, decomposition of the fluorine-based material and the like and reduction in molecular weight by the hydrogen peroxide radical are suppressed. . That is, the deterioration of the seal member is suppressed. As a result, a gas seal between the electrolyte membrane and the separator is ensured, and problems due to mixing of reaction gases are also eliminated. Moreover, deterioration of the electrolyte membrane and the electrode is also suppressed. Therefore, the polymer electrolyte fuel cell of the present invention is excellent in durability.

  In the polymer electrolyte fuel cell of the present invention, a peroxide decomposition catalyst is disposed on a seal member that seals between the electrolyte membrane and the separator. For this reason, even if hydrogen peroxide is generated during operation, the hydrogen peroxide is quickly decomposed and rendered harmless in the vicinity of the electrode end. Therefore, in the polymer electrolyte fuel cell of the present invention, the seal member, the electrolyte membrane, and the electrode are hardly deteriorated, and the battery performance is hardly deteriorated even when operated for a long time.

  Hereinafter, embodiments of the polymer electrolyte fuel cell of the present invention will be described. The polymer electrolyte fuel cell of the present invention is not limited to the following embodiment. The polymer electrolyte fuel cell of the present invention can be implemented in various forms that have been modified or improved by those skilled in the art without departing from the scope of the present invention.

  As described above, the polymer electrolyte fuel cell of the present invention includes an electrolyte membrane electrode assembly comprising an electrolyte membrane having ionic conductivity, and a pair of electrodes disposed on both sides of the electrolyte membrane, and the electrolyte. And a separator that sandwiches the membrane electrode assembly from both sides, and a peroxide decomposition catalyst that decomposes peroxide is disposed on a seal member that seals between the electrolyte membrane and the separator.

  The polymer electrolyte fuel cell of the present invention may follow the configuration of a known polymer electrolyte fuel cell in that it comprises an electrolyte membrane electrode assembly (hereinafter referred to as “MEA” as appropriate) and a separator. . Hereinafter, the MEA and the separator will be described in order.

  The MEA is composed of an electrolyte membrane and a pair of electrodes disposed on both sides thereof. The pair of electrodes, that is, the fuel electrode and the oxygen electrode may be constituted of a catalyst layer and a diffusion layer, respectively. The catalyst layer is a reaction field for an electrochemical reaction, and includes an electrode catalyst such as platinum supported on carbon and a polymer electrolyte. The diffusion layer serves to supply a reaction gas to the catalyst layer and exchange electrons with the catalyst layer, and is made of a porous material such as carbon cloth. In this case, a catalyst layer for each electrode may be formed on both surfaces of the electrolyte membrane described later, and a diffusion layer may be laminated on the surface of each catalyst layer to form an MEA.

  The type of the electrolyte membrane is not particularly limited. For example, a perfluorinated sulfonic acid film, a perfluorinated phosphonic acid film, a perfluorinated carboxylic acid film, a fluorinated hydrocarbon-based graft film, a perhydrocarbon-based graft film, a wholly aromatic film, or the like can be used. Moreover, you may use the composite polymer film which reinforce | strengthened the mechanical characteristic containing reinforcement materials, such as a polytetrafluoroethylene (PTFE) and a polyimide. In particular, in consideration of durability and the like, it is desirable to use a perfluorinated polymer film. Among these, it is desirable to use a perfluorinated sulfonic acid membrane because of its high performance as an electrolyte. Examples of perfluorinated sulfonic acid membranes include “Nafion” (registered trademark, manufactured by DuPont), “Aciplex” (registered trademark, manufactured by Asahi Kasei Corporation), “Flemion” (registered trademark, manufactured by Asahi Glass Co., Ltd.), etc. Can be mentioned.

  The separator is disposed on both sides of the MEA. As the separator, a fired carbon, molded carbon, or a stainless steel material whose surface is coated with a noble metal or a carbon material, which has high current collecting performance and is relatively stable even in an oxidizing water vapor atmosphere, may be used.

  As described above, when a polymer electrolyte fuel cell is constituted by the MEA and the separator, a gap is generated between the electrolyte membrane and the separator. This gap is sealed by a sealing member. The material of the seal member is not particularly limited. For example, although the gas permeability coefficient is slightly large, it does not lose elasticity at the operating temperature of the battery, it is a chemically stable fluororesin, and the chemical stability is slightly inferior to that of the fluororesin, but epoxy resin with a small gas permeability coefficient Examples thereof include silicone resins, addition polymerization type isobutylene resins having good sealing properties and adhesiveness, polyethylene naphthalate (PEN) resins and polyimide resins having a small gas permeability coefficient, and phenol resins having good heat resistance. These resins may be appropriately used as an adhesive or in the form of a film.

In the polymer electrolyte fuel cell of the present invention, a peroxide decomposition catalyst is disposed on the seal member. The peroxide decomposition catalyst is not particularly limited as long as it has a catalytic action for decomposing peroxide. For example, macrocyclic metal complex, poorly soluble metal oxides, insoluble phosphates, insoluble fluoride, alone one selected from sparingly soluble tungsten salt and the like, or Ru used as a mixture of two or more. Examples of the macrocyclic metal complex include porphyrin, phthalocyanine, and derivatives thereof having Co, Fe, Ti, Al, Ce and the like as a central atom. Examples of the hardly soluble metal oxide include MbO ₂ , PbO ₂ , and RuO _{2 having} high electrical conductivity, such as Sb ₂ O ₃ , Nb ₂ O ₃ , Ta ₂ O ₅ , Nb ₂ O ₅ , and W ₂ O _{2 having} low electrical conductivity. _{3, SnO 2, Cr 2 O} 3, CeO 2, La 2 O 3 and the like. In addition, the hardly soluble metal oxide may be Sb ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ , or HfO ₂ . Examples of the hardly soluble phosphate include AlPO ₄ , TiPO ₄ , FePO ₄ , CrPO ₄ , CePO ₄ , Zr ₃ (PO ₄ ) ₄ , LaPO _{4 and the} like. Examples of the hardly soluble fluoride include AlF ₃ , FeF ₃ , CrF ₃ , CeF ₃ , ZrF ₄ , LaF _{3 and the} like. Examples of the slightly soluble tongue salts include FeWO ₄ , MnWO ₄ , (Fe, Mn) WO ₄ , CaWO ₄ , CuWO ₄ , Cu ₂ WO ₄ (OH) ₂ , Al ₂ (WO ₄ ) ₃ , SrWO ₄ , BaWO _4. , Ag ₂ WO ₄ , ZnWO ₄ , SnWO ₄ , Ce ₂ (WO ₄ ) _{3 and the} like.

Especially, poorly conductive metal oxides, macrocyclic metal complexes, sparingly soluble phosphates, sparingly soluble fluorides and sparingly soluble tungsates with low electrical conductivity are low in electrical conductivity. Even when segregated, the insulation between the electrodes is not hindered. For this reason, it is more suitable than noble metals and poorly soluble metal oxides with high electrical conductivity. In particular , CeO ₂ , CePO ₄ , CeF ₃ , and RuO ₂ are suitable because of their high peroxide decomposition performance.

The peroxide decomposition catalyst may adhere to the surface of the sealing member or may be contained in the sealing member. Moreover, both of these may be sufficient. Depending on the arrangement form of the peroxide decomposition catalyst, the peroxide decomposition catalyst can be arranged on the seal member by the following methods (1) to (4), for example.
(1) A peroxide decomposition catalyst such as powder or sol is mixed with a predetermined resin as a raw material of the seal member.
(2) A peroxide decomposition catalyst solution in which a peroxide decomposition catalyst is dispersed in a solvent such as water is spray-coated on the surface of the seal member. Alternatively, the seal member is immersed in the peroxide decomposition catalyst solution.
(3) A peroxide decomposition catalyst is adhered to the surface of the seal member by vapor deposition, sputtering, laser ablation, or the like.
(4) In order to improve the elasticity of the sealing member, when the sealing member contains resin beads such as SiO ₂ and ZrO ₂ , the resin beads are prepared with a peroxide decomposition catalyst. Further, a peroxide decomposition catalyst is attached to the surface of the conventional resin beads.

  The amount of the peroxide decomposition catalyst to be arranged is preferably 0.1 wt% or more when the weight of the seal member is 100 wt%. This is because when the amount is less than 0.1 wt%, the effect of decomposing peroxide is small. It is more suitable when it is 0.2 wt% or more. On the other hand, the amount of peroxide decomposition catalyst is desirably 1 wt% or less. If it exceeds 1 wt%, the mechanical properties of the seal member may be affected, such as a decrease in elongation and an excessive increase in elastic modulus. Excessive addition is also uneconomical. More preferably, it is 0.5 wt% or less.

  Moreover, when employ | adopting the method of said (1)-(3), it is desirable that the average particle diameter of the peroxide decomposition catalyst to arrange | position shall be 10 micrometers or less. When it exceeds 10 μm, the adhesion between the electrolyte membrane, the separator and the seal member is lowered, which may affect the mechanical properties of the seal member. The average particle diameter of the peroxide decomposition catalyst is more preferably 1 μm or less.

  Here, when employing the above methods (2) and (3), the peroxide decomposition catalyst may be adhered to the surface of the seal member in a substantially uniform film shape, or dispersed and adhered in an island shape. You may do it. Moreover, in order to fully exhibit the decomposition effect of peroxide, it is preferable that the thickness of the attached peroxide decomposition catalyst is 0.01 μm or more. For example, when it is attached in an island shape, the thickness may be 0.01 μm or more on the assumption that it is attached to the entire surface of the seal member.

  Moreover, when employ | adopting the method of said (2)-(4), it is desirable to arrange | position a peroxide decomposition catalyst by high concentration in the electrode edge part vicinity. In the vicinity of the end of the electrode, hydrogen peroxide is easily generated, and is liable to stay in a state dissolved in the generated water. Therefore, the peroxide can be effectively decomposed by arranging the peroxide decomposition catalyst at a high concentration in the vicinity of the end portion of the electrode.

  Hereinafter, two embodiments of the polymer electrolyte fuel cell of the present invention will be described with reference to the drawings. First, the first embodiment will be described. FIG. 1 shows a partial cross-sectional view of the polymer electrolyte fuel cell according to the first embodiment of the present invention. As shown in FIG. 1, the polymer electrolyte fuel cell 1 includes an electrolyte membrane 2, a fuel electrode 3, an oxygen electrode 4, a separator 5, and a seal member 6.

  The electrolyte membrane 2 is made of Nafion 112 (trade name, manufactured by DuPont). The thickness of the electrolyte membrane 2 is 50 μm.

The fuel electrode 3 is disposed on one surface side of the electrolyte membrane 2. The fuel electrode 3 includes a fuel electrode side catalyst layer and a fuel electrode side diffusion layer (not shown). The fuel electrode side catalyst layer is formed on the surface of the electrolyte membrane 2. The fuel electrode side catalyst layer has a platinum catalyst (hereinafter referred to as “Pt / C catalyst”) supported on carbon. The amount of platinum per unit area of the fuel electrode side catalyst layer is 0.2 mg / cm ² . The fuel electrode side diffusion layer is made of carbon cloth. The fuel electrode side diffusion layer is formed by being laminated on the fuel electrode side catalyst layer.

The oxygen electrode 4 is disposed on the other surface side of the electrolyte membrane 2, that is, on the side opposite to the fuel electrode 3 with the electrolyte membrane 2 interposed therebetween. Similarly to the fuel electrode 3, the oxygen electrode 4 includes an oxygen electrode side catalyst layer and an oxygen electrode side diffusion layer (not shown). The oxygen electrode side catalyst layer is formed on the surface of the electrolyte membrane 2. The oxygen electrode side catalyst layer has a Pt / C catalyst and CePO ₄ . CePO ₄ is a peroxide decomposition catalyst and is contained at a ratio of 1 wt% with respect to Pt. The amount of platinum per unit area of the oxygen electrode side catalyst layer is 0.5 mg / cm ² . The oxygen electrode side diffusion layer is made of carbon cloth. The oxygen electrode side diffusion layer is formed by being laminated on the oxygen electrode side catalyst layer. The fuel electrode 3 and the oxygen electrode 4 correspond to a pair of electrodes constituting the present invention. The MEA is composed of the electrolyte membrane 2, the fuel electrode 3, and the oxygen electrode 4.

  The separators 5 are disposed on both sides of the MEA. The separator 5 clamps the MEA from both sides. The separator 5 is made of molded carbon. In the separator 5, a fuel gas channel 51 supplied to the fuel electrode 3 and an oxidant gas channel 52 supplied to the oxygen electrode 4 are formed.

The seal member 6 is disposed between the electrolyte membrane 2 and the separator 5 and between the opposing separators 5. The seal member 6 is made of an epoxy resin containing CeO ₂ having an average particle diameter of 0.01 μm as a peroxide decomposition catalyst. CeO ₂ is contained at a ratio of 0.5 wt% with respect to the weight of the epoxy resin.

  During operation of the polymer electrolyte fuel cell 1, fuel gas is supplied through the fuel gas passage 51. An oxidant gas is supplied through the oxidant gas flow path 52. And water produces | generates by a battery reaction. Hydrogen peroxide is also produced as a by-product. By-produced hydrogen peroxide dissolves in the produced water. The generated water stays in the vicinity of the electrode end 7. However, since the seal member 6 contains a peroxide decomposition catalyst, hydrogen peroxide in the generated water is rapidly decomposed. Therefore, deterioration of the seal member 6, the electrolyte membrane 2, the fuel electrode 3, and the oxygen electrode 4 is suppressed.

Next, a second embodiment will be described. Only the seal member is different between the second embodiment and the first embodiment. Therefore, only the differences will be described here. FIG. 2 is a partial cross-sectional view of the polymer electrolyte fuel cell according to the second embodiment of the present invention. In addition, about the site | part corresponding to FIG. 1, it shows with the same code | symbol. As shown in FIG. 2, the seal member 8 is disposed between the electrolyte membrane 2 and the separator 5. The sealing member 8 is a PEN resin film having a CeO ₂ layer having a thickness of 0.01 μm formed on the surface. The polymer electrolyte fuel cell 1 of this embodiment has the same effects as the polymer electrolyte fuel cell of the first embodiment.

  Three types of seal members containing a peroxide decomposition catalyst were produced and their durability was evaluated. Moreover, the resolution | decomposability of the peroxide was investigated about various peroxide decomposition | disassembly catalysts. Hereinafter, it demonstrates in order.

<Durability evaluation of seal member>
(1) Preparation of seal member Powdered CeO ₂ (average particle diameter 1 μm) was used as the peroxide decomposition catalyst. In addition, the material of the sealing member includes (a) SBR (styrene butadiene rubber); “CA-141” manufactured by Cemedine Co., Ltd., (b) silicone; “three bond 1211” manufactured by ThreeBond Co., Ltd., (c) epoxy resin; Konishi Three types of “Bond Quick 5” manufactured by Co., Ltd. were used. First, CeO ₂ and the above three kinds of materials were mixed on a sheet made of Teflon (registered trademark, manufactured by DuPont), respectively, and formed into a thin piece of 2 × 2 cm and a thickness of 0.2 mm. Next, after being held at 80 ° C. for 2 hours to be cured, it was peeled off from the sheet and allowed to stand at room temperature for a whole day and night. Furthermore, after heating in vacuum at a temperature of 80 ° C. for 2 hours, it was gradually cooled to obtain a seal member. The weight W1 of each sealing member at this time was measured.

(2) Durability Evaluation First, 200 ml of a 1 wt% aqueous hydrogen peroxide solution was prepared in a pressure vessel made of SUS316 having a PTFE inner cylinder. To this aqueous hydrogen peroxide solution, 10 ppm of iron ions (Fe ²⁺ ) serving as an OH radical generating catalyst was added (using the reagent FeCl ₂ .6H ₂ O) to prepare an aqueous hydrogen peroxide solution containing iron ions. Next, the three types of sealing members produced above were immersed in the prepared aqueous hydrogen peroxide solution, heated to 100 ° C. and held for 8 hours. Thereafter, the seal member was taken out and washed with running water. And after heating in vacuum at 80 degreeC temperature for 2 hours and cooling gradually, the weight W2 of each sealing member was measured. The weight change rate ΔW (%) before and after being immersed in the aqueous hydrogen peroxide solution was determined from the following formula [ΔW = (W1−W2) / W1 × 100]. Table 1 shows the weight change rate ΔW (%) of each seal member. For comparison, Table 1 also shows the results of the sealing member produced without mixing the peroxide decomposition catalyst.

表１に示すように、いずれのシール部材においても、過酸化物分解触媒を混合すると、重量変化が少なかった。これより、過酸化物分解触媒を混合することで、過酸化水素のラジカル化を抑制し、シール部材の分解等を抑制できることが確認された。

As shown in Table 1, in any sealing member, when the peroxide decomposition catalyst was mixed, the weight change was small. From this, it was confirmed that by mixing the peroxide decomposition catalyst, radicalization of hydrogen peroxide can be suppressed and decomposition of the seal member and the like can be suppressed.

<Resolution investigation of peroxide>
For various peroxide decomposition catalysts shown in Table 2 below, the resolution of the peroxide was investigated. Peroxide resolution was evaluated by the following test. First, 30 ml of a 1 wt% aqueous hydrogen peroxide solution was prepared in a pressure vessel made of SUS316 having a PTFE inner cylinder. Next, 0.1 g of each peroxide decomposition catalyst was added to the aqueous hydrogen peroxide solution. And after hold | maintaining at the temperature of 100 degreeC for 1 hour, the hydrogen peroxide concentration E2 of aqueous solution was calculated | required. The hydrogen peroxide concentration is determined by utilizing the fact that the constant potential oxidation current (after 10 minutes) at 1.2 V vs. SHE in sulfuric acid at a concentration of 0.1 mol / L is proportional to the hydrogen peroxide concentration. It was determined using a calibration curve of concentration-current value (constant potential electrochemical oxidation method).

  From the change in the hydrogen peroxide concentration of the aqueous hydrogen peroxide solution, the decomposition rate ΔE of hydrogen peroxide was determined from the following equation [ΔE = (1−E2) × 100]. Table 2 shows the average particle diameter and hydrogen peroxide decomposition rate ΔE (%) of each peroxide decomposition catalyst.

表２に示すように、試験したすべての過酸化物分解触媒が過酸化水素を分解した。これより、過酸化物分解触媒によれば、過酸化水素は速やかに分解されることが確認された。

As shown in Table 2, all tested peroxide decomposition catalysts decomposed hydrogen peroxide. From this, it was confirmed that according to the peroxide decomposition catalyst, hydrogen peroxide was rapidly decomposed.

1 is a partial cross-sectional view of a polymer electrolyte fuel cell according to a first embodiment of the present invention. The partial cross section figure of the polymer electrolyte fuel cell which is 2nd embodiment of this invention is shown.

Explanation of symbols

1: Polymer electrolyte fuel cell 2: Electrolyte membrane 3: Fuel electrode 4: Oxygen electrode 5: Separator 6, 8: Seal member 7: End of electrode

Claims (3)

An electrolyte membrane electrode assembly comprising an electrolyte membrane having ionic conductivity and a pair of electrodes disposed on both sides of the electrolyte membrane;
A separator for sandwiching the electrolyte membrane electrode assembly from both sides;
With
The seal member that seals between the electrolyte membrane and the separator is provided with a peroxide decomposition catalyst that decomposes peroxide .
The peroxide decomposition catalyst is a macrocyclic metal complex composed of porphyrin, phthalocyanine, or a derivative thereof having Co, Fe, Ti, Al, Ce or the like as a central atom, MnO ₂ , PbO ₂ , RuO ₂ , Sb ₂ O. _{3, Nb 2 O 3, Ta} 2 O 5, Nb 2 O 5, WO 3, SnO 2, Cr 2 O 3, CeO 2, La 2 O 3, ZrO 2, Y 2 O 3, or poorly consisting HfO ₂ A sparingly soluble phosphate composed of a soluble metal oxide, AlPO ₄ , TiPO ₄ , FePO ₄ , CrPO ₄ , CePO ₄ , Zr ₃ (PO ₄ ) ₄ , or La ₄ PO ₄ , AlF ₃ , FeF ₃ , CrF ₃ , A sparingly soluble fluoride composed of CeF ₃ , ZrF ₄ , or LaF ₃ , and FeWO ₄ , MnWO ₄ , (Fe, Mn) WO ₄ , CaWO ₄ , CuWO ₄ , Cu A group of poorly soluble tongues consisting of ₂ WO ₄ (OH) ₂ , Al ₂ (WO ₄ ) ₃ , SrWO ₄ , BaWO ₄ , Ag ₂ WO ₄ , ZnWO ₄ , SnWO ₄ , or Ce ₂ (WO ₄ ) ₃ polymer electrolyte fuel cell, characterized in der Rukoto least one selected from the.   2. The polymer electrolyte fuel cell according to claim 1, wherein the amount of the peroxide decomposition catalyst is 0.1 wt% or more and 1 wt% or less when the weight of the seal member is 100 wt%. 3. The polymer electrolyte fuel cell according to claim 1, wherein the peroxide decomposition catalyst has an average particle size of 10 μm or less.

Images