Fuel cell having a sealing member comprising a substrate layer containing inorganic zeolite

Abstract

The present invention provides a means for substantially suppressing the decrease in power generation performance caused by dibutylamine contained as an impurity in a fuel cell cell having a sealing member comprising a substrate layer containing polyphenylene ether. [Solution] One aspect of the present invention relates to a fuel cell having a sealing member comprising a base layer containing polyphenylene ether, a binder layer disposed on the surface of the base layer, and an adhesive layer disposed on the surface of the binder layer, wherein the base layer contains inorganic zeolite.

Description

Technical Field

[0001] The present invention relates to a fuel cell unit having a sealing member provided with a base material layer containing inorganic zeolite.

Background Art

[0002] A fuel cell generates electric power by electrochemically reacting hydrogen and oxygen. In principle, the only product generated along with power generation of the fuel cell is water. Therefore, it has attracted attention as a clean power generation system that places almost no burden on the global environment.

[0003] A fuel cell is configured with a membrane electrode assembly (hereinafter also referred to as "MEA"), in which electrode catalyst layers are arranged on both surfaces of an electrolyte membrane, as a basic unit. During operation of the fuel cell, an electromotive force is obtained by supplying a fuel gas containing hydrogen to the electrode catalyst layer on the anode (fuel electrode) side and an oxidizing gas containing oxygen to the electrode catalyst layer on the cathode (air electrode) side, respectively. An oxidation reaction proceeds at the anode, and a reduction reaction proceeds at the cathode, thereby supplying electromotive force to an external circuit.

[0004] In a fuel cell, usually, gas diffusion layers are disposed on the outer side of each electrode catalyst layer of the MEA, and separators are further disposed on the outer side of the gas diffusion layers, whereby a fuel cell unit is constituted. The fuel cell is usually used as a combination of a plurality of required fuel cell units (hereinafter also referred to as "fuel cell stack") based on desired electric power.

[0005] The separator not only blocks the fuel gas and air supplied to each fuel cell unit, but also functions as a current transmission part to the outside. For this reason, the fuel cell unit usually has a sealing member that blocks the fuel gas and air at the separator.

[0006] For example, Patent Document 1 describes a multilayer sheet including a base material layer (A) containing 40 to 99.9% by mass of polyphenylene ether (a1), 0 to 59.9% by mass of polystyrene (a2), and an epoxy group-containing polymer (a3), and an adhesive layer (B) containing an acid-modified polyolefin. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2022 / 211081 [Overview of the project] [Problems that the invention aims to solve]

[0008] As described above, a sealing member that can be used in fuel cell cells has been developed. However, conventional sealing members for fuel cell cells have problems in terms of the materials used. For example, polyphenylene ether, which is a resin contained in the base layer of the multilayer sheet described in Patent Document 1, generally uses dibutylamine as a co-catalyst during resin synthesis to improve synthesis efficiency. However, it is difficult to completely remove dibutylamine in the purification process of the synthesized resin. For this reason, molded articles using polyphenylene ether inevitably contain a certain amount of dibutylamine as an impurity. Dibutylamine can be a cause of discoloration, odor, and / or leached components in molded products. Furthermore, when a molded article using polyphenylene ether is used as a component of a fuel cell, the dibutylamine contained as an impurity can poison the carbon catalyst used as the electrode catalyst in the fuel cell, causing a decrease in power generation performance.

[0009] Therefore, the present invention aims to provide a means for substantially suppressing the decrease in power generation performance caused by dibutylamine contained as an impurity in a fuel cell cell having a sealing member comprising a substrate layer containing polyphenylene ether. [Means for solving the problem]

[0010] The inventors investigated various means to solve the above-mentioned problems. The inventors found that in a sealing member for a fuel cell cell having a base layer containing polyphenylene ether, by incorporating inorganic zeolite into the base layer, dibutylamine contained as an impurity can be adsorbed onto the inorganic zeolite, thereby substantially suppressing the decrease in power generation performance caused by dibutylamine. Based on the above findings, the inventors completed the present invention.

[0011] In other words, the present invention encompasses the following aspects and embodiments. (Embodiment 1) A substrate layer containing polyphenylene ether, A binding layer is placed on the surface of the base material layer, An adhesive layer and Equipped with, The aforementioned substrate layer contains an inorganic zeolite, A fuel cell having a sealing member. [Effects of the Invention]

[0012] The present invention makes it possible to provide a means for substantially suppressing the decrease in power generation performance caused by dibutylamine contained as an impurity in a fuel cell cell having a sealing member comprising a substrate layer containing polyphenylene ether. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view of a preferred embodiment of a sealing member included in a fuel cell according to one aspect of the present invention. [Figure 2] This graph shows the results of gas chromatography (GC) analysis of gaseous components volatilized in airtight containers containing a control test sample and test samples containing zeolite A, B, or C, during an analysis test of volatile substances. In the graph, the horizontal axis represents the test sample, and the vertical axis represents the mass concentration (ppm) of each volatile substance calculated based on the GC analysis. [Figure 3]This graph shows the current-voltage characteristics measured in the power generation performance test using a control test fuel cell, either in the absence of dibutylamine or in the presence of 3.1 ppm of dibutylamine. In the graph, the horizontal axis represents current density (A / cm2), and the vertical axis represents voltage (V). [Modes for carrying out the invention]

[0014] Preferred embodiments of the present invention will be described in detail below.

[0015] One aspect of the present invention relates to a fuel cell having a sealing member. Figure 1 shows a cross-sectional view of a preferred embodiment of the sealing member included in the fuel cell according to one aspect of the present invention. The sealing member included in the fuel cell according to this aspect will be described below with reference to the drawings.

[0016] As shown in Figure 1, the sealing member 100 included in the fuel cell cell of this embodiment comprises a base layer 11, a connecting layer 12 disposed on the surface of the base layer 11, and an adhesive layer 13 disposed on the surface of the connecting layer 12. The sealing member 100 is usually in the shape of a plate or sheet. The connecting layer 12 and the adhesive layer 13 may be disposed on only one surface of the base layer 11, or on both surfaces of the base layer 11.

[0017] In the sealing member included in the fuel cell of this embodiment, the base material layer contains polyphenylene ether. Since this material is relatively inexpensive and has sufficient strength and processability, it is suitable as a base material for the sealing member included in the fuel cell.

[0018] In the sealing member included in the fuel cell unit of the present embodiment, the base material layer contains inorganic zeolite. The present inventors have found that in a sealing member for a fuel cell unit provided with a base material layer containing polyphenylene ether, by blending inorganic zeolite into the base material layer, dibutylamine contained as an impurity can be adsorbed onto the inorganic zeolite, thereby making it possible to substantially suppress the decrease in power generation performance caused by dibutylamine. Therefore, the fuel cell unit of the present embodiment having the sealing member with the above configuration can substantially suppress the decrease in power generation performance caused by dibutylamine contained as an impurity.

[0019] In the sealing member included in the fuel cell unit of the present embodiment, the counter ion of the inorganic zeolite contained in the base material layer is preferably sodium. The structure of the inorganic zeolite is preferably Y-type. The pore diameter of the inorganic zeolite is preferably in the range of 1 to 10 Å. The silica / alumina ratio of the inorganic zeolite is preferably in the range of 1 to 100. The average particle diameter of the inorganic zeolite is preferably in the range of 1 to 10 μm. The added amount of the inorganic zeolite is preferably in the range of 1000 to 10000 ppm relative to the total mass of the base material layer. Since the base material layer of the sealing member contains the inorganic zeolite having the characteristics exemplified above, the fuel cell unit of the present embodiment can substantially suppress the decrease in power generation performance caused by dibutylamine contained as an impurity.

[0020] In the sealing member included in the fuel cell unit of the present embodiment, the structure of the inorganic zeolite contained in the base material layer can be determined, for example, by a transmission electron microscope (TEM) or a scanning electron microscope (SEM). The pore diameter and average particle diameter of the inorganic zeolite can be determined, for example, by a gas adsorption method, a molecular probe method, a mercury intrusion porosimetry method, or small-angle X-ray scattering (SAXS). The counter ion and silica / alumina ratio of the inorganic zeolite can be determined, for example, by performing elemental analysis of the base material layer by X-ray photoelectron spectroscopy (XPS).

[0021] In the sealing member included in the fuel cell of this embodiment, the bonding layer is a layer for improving the adhesion between the base material layer and the adhesive layer. The material constituting the bonding layer can be appropriately selected by a person skilled in the art based on the combination of materials of the base material layer and the adhesive layer. Preferably, the bonding layer is made of a primer used in the art.

[0022] In the sealing member included in the fuel cell of this embodiment, the adhesive layer is a layer that ensures adhesion to other members and blocks fuel gas and air. The material constituting the adhesive layer is preferably an acid-modified olefin from the viewpoint of water resistance, and more preferably an acid-modified polypropylene from the viewpoint of heat resistance. By providing the sealing member with an adhesive layer made of the material exemplified above, the fuel cell of this embodiment can have high sealing performance even in high temperature and highly acidic environments.

[0023] In each embodiment of the present invention, the impurity removal performance of the sealing member contained in the fuel cell can be evaluated, for example, by gas chromatography (GC) analysis of the gaseous components that have volatilized into the airtight container in which the sealing member contained in the fuel cell is sealed.

[0024] In each embodiment of the present invention, the power generation performance of a fuel cell cell having a sealing member can be evaluated, for example, by measuring the current-voltage characteristics of the fuel cell cell.

[0025] As described in detail above, a fuel cell cell according to one aspect of the present invention can substantially suppress the decrease in power generation performance caused by dibutylamine contained as an impurity. Therefore, a fuel cell cell according to one aspect of the present invention can be suitably used in fuel cells applied to power mobile vehicles such as automobiles, railways, ships, and aircraft, or to household or commercial power sources. [Examples]

[0026] The present invention will be described in more detail below using examples. However, the technical scope of the present invention is not limited to these examples.

[0027] <I: Preparation of Test Samples> [I-1: Preparation of Test Sample of Seal Member for Fuel Cell Unit] Inorganic zeolite was blended into a base material containing polyphenylene ether as a main component. Using the base material as a base material layer, a test sample of a seal member for a fuel cell unit including the base material layer, a tie layer and an adhesive layer was produced as shown in Figure 1. As a control, a test sample was produced in the same procedure as described above except that no inorganic zeolite was blended. The blended inorganic zeolites are shown in Table 1.

[0028] [Table 1]

[0029] [I-2: Fabrication of Fuel Cell] A cathode electrode catalyst layer and an anode electrode catalyst layer were transferred and bonded to an electrolyte membrane to produce a membrane electrode assembly (MEA). Using the control test sample produced by the procedure of I-1 above and the test sample blended with zeolite A, B or C as seal members, the MEA was sandwiched between separators to fabricate a test fuel cell unit.

[0030] <II: Evaluation of Test Samples> [II-1: Volatile Substance Analysis Test] The control test sample prepared according to the procedure in I-1 above, and the test sample containing zeolite A, B, or C, were sealed in an airtight container. The temperature was increased from 50°C to 200°C at a rate of 10°C / min, and the volatile gaseous components were collected. The collected gaseous components were cooled and liquefied. This liquefied sample was injected into a gas chromatography (GC) apparatus (JEOL, Jms-T2000GC) and analyzed under conditions of increasing temperature from 40°C to 250°C at a rate of 10°C / min. Known amounts of each volatile component were used as standard samples and subjected to GC analysis under the same conditions. Based on the results of the GC analysis of the standard samples, a concentration calibration curve for each volatile component was created. By comparing the peak retention time and peak area in the GC chromatogram of the standard samples with the peak retention time and peak area in the GC chromatogram of the test samples, each volatile component in the test sample was identified, and the mass concentration (ppm) of each volatile component was calculated. The results are shown in Figure 2. In the figure, the horizontal axis represents the test sample, and the vertical axis represents the mass concentration (ppm) of each volatile substance calculated based on GC analysis.

[0031] As shown in Figure 2, the test sample with inorganic zeolite incorporated into the base layer suppressed the volatilization of all volatile substances, including toluene, styrene, amine dehydrogenates, and dibutylamine, to approximately 1 / 10th of the amount compared to the control test sample. From these results, it was confirmed that the sealing member for fuel cell cells of the present invention, which contains inorganic zeolite in the base layer, can reduce the volatilization of contaminants.

[0032] [II-2: Power Generation Performance Test] The current-voltage characteristics were measured using a control test fuel cell prepared according to the procedure in I-2 above, either in the absence of dibutylamine or in the presence of 3.1 ppm of dibutylamine. The results are shown in Figure 3. In the figure, the horizontal axis represents the current density (A / cm²). 2 The vertical axis shows the voltage (V).

[0033] As shown in Figure 3, in the presence of 3.1 ppm of dibutylamine, the voltage of the fuel cell decreased at high current densities compared to the absence of dibutylamine. This result confirms that dibutylamine can reduce the power generation performance of fuel cells.

[0034] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail for the purpose of clearly illustrating the present invention, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to add, delete, and / or replace some of the configurations in each embodiment with other configurations. [Explanation of Symbols]

[0035] 100...Sealing material included in the fuel cell, 11...Base layer, 12...Binder layer, 13...Adhesive layer

Claims

[Claim 1] A substrate layer containing polyphenylene ether, A binding layer is placed on the surface of the base material layer, An adhesive layer and Equipped with, The aforementioned substrate layer contains an inorganic zeolite, A fuel cell having a sealing member.

Images