TWI343669B - A method to manufacture the membrane electrode assembly in fuel cell - Google Patents

Description

1343669 IX. Description of the invention: [Technical field to which the invention pertains] ^ The invention belongs to the technical field of material fabrication of chemistry and chemical industry, and relates to a membrane electrode assembly required for simple production of a fuel cell stack, mainly by using a multi-pass spray of inert gas The spraying method uniformly disperses the catalyst slurry on the surface of the carbon gas diffusion layer until the required catalyst content, and then combines with the proton exchange membrane to form a membrane electrode group. [Prior Art] For a proton exchange membrane fuel cell (PEMFC), a single element that combines an anode, a proton exchange membrane, and a cathode into a sandwich structure is called a membrane electrode assembly (MEA). MEA is the core part of PEMFC. The main electrochemical reaction of the battery occurs here. Therefore, the performance of MEA directly determines the PEMFC performance catalyst layer design directly affects the total effective surface area of the effective catalyst between the reaction gas and the electrolyte interface. The catalyst layer must have two functions: one is the ionomer component, which is responsible for providing the ion (H+) conduction channel in the electrochemical reaction; the other is the gas component, The reaction gas can be quickly and smoothly transmitted to the channel of the catalyst surface. In proton exchange membrane fuel cells, proton conducting polymers are commonly used as binders, the most commonly used NafionC trade name, and the sulfonate functional group responsible for ion conduction in Nafion is hydrophilic. 'The polytetrafluoroethylene (PTFE) backbone is hydrophobic, and the hydrophobic chain is the main gas channel in the electrode catalyst layer. It must be able to balance the hydrophilic ion conduction. Channels and hydrophobic gas channels are used for maximum efficiency. The anode is mainly composed of carbon cloth (or carbon paper) and a catalyst. It is usually made by coating a carbon cloth (or carbon paper) with a catalyst mixed with platinum and carbon powder. According to the different mechanisms, it can be divided into layers of gas diffusion layer (diffUSi〇n 'lay^r) and 5 carbon paper). It is a carbon cloth (or outside the area and area, and can be used for 7 waves, Expanding the channel of the reaction zone of the catalyst. When the hydrogen molecule is supplied, the diffusion layer of the process is required to reach the diffusion layer of the process body near the catalyst. As a second formula (4), the region is called the gasification in the gas. The place where the reaction is studied, that is, the PEMFC and the box; ρ by. Hawthorn injury, in order to increase the reaction area and reduce the platinum content, and reduce the diwood f, as a catalyst carrier (s_〇rt) to improve electrocatalytic;匕 匕 匕 ί ί ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' As with the anode side, carbon cloth (or carbon is used, and in the net scorpion, the carbon cloth (or carbon paper) in the catalyst-attached pole is diffused to the electrons that will participate in the reaction, and the absorption stone is formed. f water is derived. In the active layer of the cathode, the oxygen molecules are 'after and after the electrons introduced by t The hydrogen separation of the proton exchange membrane and the reaction process of the disulfonate are slower than that of the anode, so the catalyst content of the cathode. The durability of the electrode group is mainly due to the reduction of cathode catalyst condensation and bismuth flux. The high temperature of the cathode will cause condensation, reduce the area of the contact wire and cause the membrane electrode to ΐ ί ί ϊ 目前 'currently inclined to develop dual-phase and three-phase catalyst to improve the operating temperature and time, the need to have anti-corrosion The ability to purify, so carbon is currently graphitized to increase its anti-vibration ability. The basic function of Bezier's membrane replacement is to block the two sides of the electrode, and the extension energy ions complete the reaction. The structure is basically porous solid state. The oxonium ions move to the oxygen side by migration and diffusion. The most commonly used is the Na fi 〇n shell-female replacement film produced by DuPont (10) P〇nt). The internal structure is made of polytetrafluoroethylene. The perfluoropolymerized polymer composed of pTFE and perfluorosulfonic acid ionomers has a molecular structure similar to that of polytetrafluoroethylene, and has a bulk network structure, many of which Pores (pore size of about lnm). In addition to Nafion, Japan

Asahi Chemical's Aciplex-S film, Asahi Glass's Flemion film, Japan's Chlorine Engineers' C film 'Dow Chemical'

Dow membranes are mainly composed of polyfluorinated sulfonic acid (pFSA), the structure is similar to that of Nafi〇n membrane, and the development of Honda stack fuel cell stack in Japan is quite fast. The proton exchange membrane mainly uses aromatic electrolytic membrane (Ar〇matic). Electrolytic membrane), its operating temperature is high, Dupont pem is about i5 °c, its operation durability is about 4 times higher than DuPont PEM. The technical bottleneck of the joint electrode group is cost (c〇st), performance (performance) and durability. The cost reduction can be started by mass production techniques, and the performance is improved by catalyst, proton exchange membrane, The nature of the gas expansion and the underlying layer is required. The durability is improved by the nature of the material and the design of the fuel cell stack, and the battery cells or battery packs are tested for a long time, and the cyclic voltammetry, battery impedance, and water discharge analysis are performed. In the research of related fields of MEA patent technology, the BaUar_d pQwer_ Systems patent has the largest output, accounting for 2% of the total number of patents. It is the most active company in the research and development of MEA patent technology. Uard p[) wer is in the technology of _ The research and development materials have 12 fines, and the investment is more than the high-end of the day. It is also the company with the most research and development team. The patent belongs to the recent patent. A total of 17 or more, the patent activity period is about _ years, and the number of patents of The Dow Chemical Company is small (about 6 pieces). " The main process of the membrane electrode group is to apply a catalyst to a gas diffusion cloth or transfer it to a proton exchange membrane. Uniform coating or transfer to gas-tolerance by brush coating (Painting), ultrasonic coating (Doctor Blading), or transfer (Decal, etc.) The gas is 7 hot pressing, such as E-Tek. The invention adopts the process on the gas diffusion layer. The advantages of early and Hebeibei coating brush coating are simple, no complicated equipment, and large 1 The production of human X is expensive and the catalyst is produced in large quantities. (IV) The advantage of variable transfer is that it can accurately control the catalyst content, and the mass production speed and electrode and proton exchange membrane 匕 == more and slower process steps, automatic mass production difficulties The advantage of the strong and the scraper is that the distribution of the catalyst is uniform and the coating can be reduced. The point is that the automation requires expensive equipment, and when the performance is not lost, the multi-pass film coating is difficult, and may not be the best. The advantages of sound wave spray coating are good distribution of catalyst distribution, good application of multi-pass film coating and automatic mass production ▲ miscellaneous and expensive equipment, (4) easy separation of mixture and if the design is not good, it will be obvious. Pressure method It is well known in the art and in the case of MEA manufacture, a method in which two components, such as PE% and electrodes, are combined using heat, pressure and/or # mixture. B〇nsi丨 et al. U.S. Patent No. 6,197,147 discloses a lamination process for the production of MEAs. The method comprises laminating an ion-conducting membrane, a catalytically active material, and a gas-permeable electronically conductive material. It is disclosed that the membrane and/or the electrically conductive material can be combined with a compound. Lithium uranium is contacted, which is then reduced to form platinum metal. 转印 The transfer method (deca 1 coman ia) is generally defined as the transfer of a pattern printed on a specially prepared transfer substrate to a material such as glass or metal. In the case of MEA elements, the pattern is a deposition pattern for the various layers used to produce the MEA, which is then transferred to an MEA substrate such as a PEM, gas or fluid distribution layer or bipolar plate. In particular, the ink composition is deposited On a blank cartridge, referred to herein as a transfer substrate, the transfer substrate and the MEA substrate are then clamped together and pressed in a heated environment. Heat heats the ink to the substrate, thereby transferring it from the substrate. The substrate is detached and deposited onto the substrate, which is then removed by peeling the transfer substrate from the deposited ink layer.

U.S. Patent No. 5,029,984 to Wilson discloses a method of producing MEAs by a transfer process. An ink composition comprising a supported platinum catalyst and a proton conducting polymer is applied to a release blank to form a film decal. The decal is then transferred to the PEM surface using a hot press. Transfer methods and lamination methods are advantageous because they can be deposited on fragile surfaces and are relatively simple to handle. The lamination process also provides high yields. However, the printing method and the lamination method cannot produce a fine pattern or a gradient in composition without additional processing. Moreover, it is difficult to align various MEA layers.

The use of continuous impregnation and printing to produce electrodes is disclosed in U.S. Patent No. 6,8,742, the disclosure of which is incorporated herein. First, the proton conducting polymer is impregnated on the surface of the substrate = carbon, paper. The impregnation can be accomplished using a variety of techniques, such as substituting the substrate into a solution comprising a proton conducting polymer. The electrocatalyst is then applied to the impregnated substrate. It is disclosed that the electrocatalyst can be applied to the substrate by any known method including spray screen printing and ink jet printing in the form of an aqueous ink of a proton conducting polymer included in the solution. ,

A method for producing MEAs using an ink composition containing stone particles and a zero-valent Pt compound is disclosed in U.S. Patent No. 6,500,217. This = discloses a method for the front and back layers of a polymer electrolyte membrane strip. After power

Shah et al. (Langmuir, 1999, Vol. 15, ρρ·1584_1587) opened a neosol (tetra) ink deposit' as a catalyst used in chemical stacks for microelectronic applications. ^

U.S. Patent No. 5,672,439 to Wilkinson et al. discloses an MEA for (10) wherein the crossover of liquid methanol from the anode to the cathode is reduced. To reduce bridging, the catalyst can be concentrated on the surface of the anode, wherein the catalyst particles promote oxidation of the methanol in the anode. ,

An electrochemical cell such as PEMFC is disclosed in U.S. Patent No. 6,24,848 to Dufer et al. The battery can include a dual layer for enhancing fluid transport within the battery. The bilayer is in contact with the pen tip and comprises a hydrophobic phase of carbon black and a hydrophobic polymer and a hydrophilic phase comprising a mixture of anisotropic and proton exchange resins. The double layer can be formed by a filtration transfer method.

U.S. Patent No. 6,156,449 to Zuber et al. discloses a catalyst layer as in a PEMFC comprising a proton conducting polymer, conductive carbon particles and fine particles of a noble metal such as platinum. The layer is formed from an ink composition comprising carbon particles and at least one organic precious metal coordination compound in a solution of the ionomer. The composition is coated and dried, wherein the coordination compound thermally decomposes during drying to form noble metal particles.

Susan G. Yan et al. in the US patent put) no. Us no problems such as deformation or wrinkles after spraying, mass production and automatic production are more difficult. When the membrane electrode assembly of the invention is developed, the inert gas is sprayed and sprayed to spray the catalyst on the air-expansion layer of the gas diffusion layer, and the bottom temperature of the gas diffusion layer is controlled by the temperature control jade white, which is very confined to the ancient six today 0 iMi: too A / 丄, "2005 /, _3 read 1 towel openly painted and then heated on the light, the direct spray directly on the film, the disadvantage is that it is not easy to control the uniformity of lamp heating and the film is considered to have the advantage of multi-channel The secondary film coating application is good, and the surface can be evenly distributed, providing the catalyst with effective and rapid uniform distribution in the catalyst layer, good distribution uniformity, good reproducibility, multi-pass glare coating, easy coating and automatic mass production. The disadvantage is that if only a small amount of MEA production catalyst waste amount will be obvious. [Summary of the Invention] Nano microporous carbon gas diffusion layer technology improvement, can _ 塞.

1343669 But its mechanical wealth (4) and (4) touch the advantages. The carbon cloth i has irregularities and needs to be leveled. The carbonized carbon layer is the size, distribution, conductivity and hydrophobicity of the hole, making it suitable for the body, the passage of the electron channel and the water. The invention mainly adopts a carbon cloth diffusion layer, and finely fills a high conductivity particle size, a solid amount, a pre-dip process number and a rolling condition to control the carbon gas diffusion layer = and distribution properties. The production process is shown in Figure 2. , 280~360 C heat treatment' The surfactant of the fluorocarbon polymer emulsion impregnated in the carbon cloth was removed, and the fluorocarbon polymer was hot-melted and sintered and dispersed on the carbon cloth. 77 The anti-clothing specifications used in the present invention are as shown in Table 1. The carbon cloth is advanced, and the carbon cloth is immersed in the diluted fluorinated propylene polymer (FEp) f = (FEP120J product of Dupont Company), and taken out. After drying in the air / Carbon cloth specifirptinn construction Plain Yarn input 2/27 Count (WxF) 48x44yarns / in Area weight 3, 4oz / yd2 Standard widths 33in thickness 15mil (〇. 38mm) density 1. 75g / cc Carbon content 99 % Oxidation rate(%per hour)at500°C 1.0 Surface resistivity(ohms/square) Outside:0. 3 Inside :〇· 29 Because the surface of the carbon cloth is uneven, it has an effect on the catalytic layer of the catalyst, so it is necessary to 1343669 ^ Perform leveling. The polytetrafluoroethylene emulsion (PTFE) and the conductive powder were formulated to a fixed ratio, wherein the polytetrafluoroethylene emulsion was a product of Dupont PTFE 30B. The conductive powder may be carbon black, graphite powder, activated carbon or inert metal powder. The preparation of the conductive powder slurry is the key technology for the production of the gas diffusion layer, and the distilled water is selected as the solvent. The force: into the conductive powder, polytetrafluoroethylene The ethylene emulsion is mixed with a dispersing agent to adjust the slurry solid content to about 5 to 40% by weight. In order to increase the viscosity of the slurry, add about 5 to 2 wt% of the sulfhydryl group, the vitamin. Mix the slurry with ultrasonic vibration or mechanically. The mixed slurry is pre-impregnated, coated on the hydrophobically treated carbon cloth, subjected to rolling forming, repeated pre-dip process and rolling step-to-five times until the charged carbon solid content and nanopore size and distribution are obtained. , to make the surface flat, each time the pre-dip process is removed from 6〇 to 12〇艽, and then subjected to cold rolling or hot rolling to 60 to 18〇t steps, the most f is so that the scales are sintered and thinned. For example, the content of f at the end of the preparation of the carbon gas is between 3 and 12 mg/cm2. The body m, specific surface area, total pore volume and average pore size (BET measured) of the carbon gas diffusion layer are shown in Table 2.

1343669 The steps of synthesizing membrane electrode sets and the like. On the contact ship, the medium, 5-solution and iso-alcohol, pt/c and % were placed. = f 1 2~3: Bu 20_/(: with __ body 2: heavy and medium, after the above three components are mechanically mixed evenly, spray "covering method will touch ΐ ΐΓ 4Γ = on the surface of 5 layers, this When the carbon gas diffuses, the surface temperature must reach 45~85C. Among them, U 65ΐ is better, and the anode 5wt/〇Nafion solution is thinly sprayed-time. The electrode and the proton are crossed, and the membrane is placed in the middle of the (four) pole. 'Take the knot by hot pressing method, hold fnt to add 2 heat to ~, hold the boot for 6 (four) seconds and then pressurize the second, move, 70~85kg/cm 'that is the membrane electrode set. Single electricity is as follows, for the single battery The performance reaches the most sensitive condition, ffi oxygen or air 'to determine the stoichiometric ratio of the pre-twist; L 々:: ', under the pressure (latm) gas temperature (ie hydrogen, ^ or 皿 度 degree " ^ battery The body temperature 'to maintain its engraving. = Temperature is set on the paper, discharge mode voltage, when the initial set of 2 voltage, then the voltage slave (4), time ί8 open / people depending on the current trend of rising trend), During the period and observe the current change ^^=temperature 2 to the order 'the conditions are the same as above, wait for the second ##°°又疋.time〇. 5 hours, and Check the current change situation, wait for its current H: Temple' to test, set voltage discharge and other experiments. This test: ., - v test condition is, temperature: hydrogen extreme humidification bottle temperature is such as Bin C, or battery Group) The temperature is 4 (rc~7Gt, the gas flow rate is variable. Back pressure: 1 type milk (depending on the need), humidification: external wetting, discharge electric power [Embodiment] Example 1 13 1343669 Carbon The cloth is first subjected to hydrophobic treatment, and the carbon cloth is immersed in the diluted 5 wt% FEP emulsion (FEP120J product of Dupont Co., Ltd.), taken out in the air and dried, and then dried at 100 ° C for 10 minutes, and then 35 (TC, 20). After the heat treatment of the fluorocarbon polymer, the fluorocarbon polymer is heat-sintered and uniformly dispersed on the carbon cloth. The pre-/3⁄4 material is mixed with a '39g. 5g Qin Lai water, added 3. 7g Triton, evenly mixed, 'additional 57. 5g The carbon black (ENSACO 250 Power, average particle size 40nm, BET 62mVg) was ball milled in a ball mill for 2 hours. After adding 3 times of polytetrafluoroethylene emulsion (PTFE), the ball was milled for 5 minutes. The mixture was taken out and placed at 71 g. In a pp beaker, add 〇.(10) fell or 8.57g of thiol cellulose, The cup was placed in an 80 C hot water bath for 2 hours, then stirred for 12 hours without heating, and finally allowed to stand for 6 hours. The solid of the obtained prepreg contained 7~. The mixed prepreg is coated on the hydrophobically treated carbon cloth by pre-dip process, and the pre-impregnated carbon cloth is dried by simmering it and drying in the continent for a while (12) (TC hot dry pressing, roller gap 〇 3 deletion The pressure-receiving step - times, until the required conductive carbon ί surface is flat - and then heat treated by 35Gt and 3G minutes to make clothes, demon melt k,, ·. With a bonding and hydrophobicity, a carbon gas diffusion layer is obtained. The process of 24 is shown in Figure 3. In the contact liquid configuration, the first solution of thunder and 30 grams of isopropyl alcohol are placed in a glass bottle, placed, heated, and mixed. Gas, the above three components are mechanically mixed ^ ΐ The hot iron plate is placed at the temperature of the electromagnetic jianer, and the carbon gas diffusion layer is placed.

When using a ship gas, such as nitrogen, to spray the surface temperature to 65 ° C, the temperature is uniformly dispersed in the carbon gas diffusion: Table: After drying, repeat the spraying action - times, straight (four) pole and Yin 1343669 ΐ The catalyst electrode is placed in a vacuum oven, and after vacuuming, 7 "c is kept for 60 minutes. The film is 35 mm thick and cold. 1. The surface is further 2. 5 wt% Nafion / valley, liquid / 彝Λ h - person. Then the catalyst electrode is 5cmx5cm and 7cmx7cm

Dupont f^3's 212 proton exchange membrane product was hot pressed, and the proton exchange membrane was placed in the middle of the anode and cathode. The three sheets were combined into a body by hot pressing. The hot pressing conditions were heated to 14 『c for 1 minute and 10 seconds, and the pressure was 8 Gkg/cm2, that is, a 5 cm×5 cm membrane electrode group, and the power of the membrane electrode group in air and oxygen, as shown in FIG. 4 and FIG. Example 2 Same as Example 1 Process 'This example changed the weight ratio of 20 wt% Pt/C to Nafion solid content from 2:1 to 1.75:1 to prepare a membrane electrode group, and the membrane electrode group was in air and The power in oxygen is shown in Figure 6 and Figure 7. Example 3 The same as the process of Example 1, this example changed the solid content ratio of 2〇wt% Pt/C and Nafi〇n solid content from 2:1 to 1.5:1 to prepare a membrane electrode group, and the membrane electrode group was in air and The power in oxygen is shown in Figure 8 and Figure 9. Example 4 The same procedure as in Example 1 was carried out, and the electrochemical propolar polarization curve of the MEA of Dupont's 212 proton exchange membrane was changed to 50" thickness of the composite proton exchange membrane containing water-absorbing ceramic micropowder, as shown in Fig. 10. [Simple description of the diagram] Figure 1. Photograph of the membrane electrode assembly. Figure 2, carbon gas diffusion layer production process. Figure 3. Process of making a membrane electrode assembly. Figure 4. Polarization curve of 15 mea in air at a weight ratio of 20 wt% Pt/C to Nafion solid content of 2:1. Figure 5. Polarization curve of MEA in oxygen at a weight ratio of 20 wt% Pt/C to Nafion solid content of 2:1. Figure 6. The weight ratio of 20 wt% Pt/C to Nafion solids by 丨, 75:1 MEA in air. Figure 7. Polarization curve of MEA in a gas ratio of 20 wt% Pt/C to Nafion solid content by 1.75:1. Figure 8. Polarization curve of MEA in a weight ratio of 20 wt% Pt/C to Nafion solid content by 丨.5:1. Figure 9. Polarization curve of MEA in oxygen ratio of 20 wt% Pt/C to Nafion solid content by weight ratio of 1.5:1. Figure 10, 50 " thickness of composite proton exchange enthalpy MEA polarization curve. [Description of main component symbols] X. Patent application scope: 1. A method for fabricating a fuel cell membrane electrode assembly, the process of which is a carbon gas diffusion layer preparation, a catalyst slurry preparation, and a multi-pass spray blasting method. Disperse on the surface of the carbon gas diffusion layer until the required catalyst content (the anode platinum amount is controlled at 〇. 0. 3mg/cm2 'the cathode platinum amount is 0. 3~0. 6mg/cni2), the catalyst electrode sheet is dried' last Then, a step of forming a membrane electrode group by hot pressing with a proton exchange membrane is carried out. 2. The method for producing a fuel cell membrane electrode assembly according to claim 1, wherein the ratio of Pt/C to Nafion solid content in the catalyst slurry is 1.2 to 3: b. The method for producing the fuel cell membrane electrode assembly of the present invention, wherein the Pt/C and Nafion solid content weight ratio is preferably 1.75:1.

Claims (1)

Mea polarizes the curve in the air. Figure 5. Polarization curve of MEA in oxygen at a weight ratio of 20 wt% Pt/C to Nafion solid content of 2:1. Figure 6. The weight ratio of 20 wt% Pt/C to Nafion solids by 丨, 75:1 MEA in air. Figure 7. Polarization curve of MEA in a gas ratio of 20 wt% Pt/C to Nafion solid content by 1.75:1. Figure 8. Polarization curve of MEA in a weight ratio of 20 wt% Pt/C to Nafion solid content by 丨.5:1. Figure 9. Polarization curve of MEA in oxygen ratio of 20 wt% Pt/C to Nafion solid content by weight ratio of 1.5:1. Figure 10, 50 " thickness of composite proton exchange enthalpy MEA polarization curve. [Description of main component symbols] X. Patent application scope: 1. A method for fabricating a fuel cell membrane electrode assembly, the process of which is a carbon gas diffusion layer preparation, a catalyst slurry preparation, and a multi-pass spray blasting method. Disperse on the surface of the carbon gas diffusion layer until the required catalyst content (the anode platinum amount is controlled at 〇. 0. 3mg/cm2 'the cathode platinum amount is 0. 3~0. 6mg/cni2), the catalyst electrode sheet is dried' last Then, a step of forming a membrane electrode group by hot pressing with a proton exchange membrane is carried out. 2. The method for producing a fuel cell membrane electrode assembly according to claim 1, wherein the ratio of Pt/C to Nafion solid content in the catalyst slurry is 1.2 to 3: b. The method for producing the fuel cell membrane electrode assembly of the present invention, wherein the Pt/C and Nafion solid content weight ratio is preferably 1.75:1. U343669 4. A method for fabricating a fuel cell membrane electrode assembly according to claim 1, wherein the catalyst slurry is firstly introduced with an inert gas, and then the catalyst is poured into a container and stirred. 5_ The method for manufacturing a fuel cell membrane electrode assembly according to claim 1, wherein the multi-pass spray blasting method has to reach a milk temperature of 85 t in the carbon gas diffusion layer. The production of the battery membrane electrode group described in the item is as follows: 2 ' Among them, the multi-pass spray blasting method disperses the catalyst money in the carbon gas, and the gas required for the blasting is inert gas. The method of applying the method of the fuel cell membrane electrode group described in the application of the patent (4), and the surface solvent evaporation of each pass of the Zhongxidao people's correction spray method|丨1' can be repeated repeatedly. Times. ^ For example, the production of the fuel cell membrane electrode group described in the first paragraph of the patent application scope, +, method, 3⁄4, wherein the catalyst electrode sheet is sprayed once with a thin solution of the pot. , the surface can be further 1 to 5 - 17