CN1315214C

CN1315214C - Method and device for making calalyst layer of fuel cell

Info

Publication number: CN1315214C
Application number: CNB200510021404XA
Authority: CN
Inventors: 王善理
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-08-04
Filing date: 2005-08-04
Publication date: 2007-05-09
Anticipated expiration: 2025-08-04
Also published as: CN1719646A

Abstract

The present invention relates to a method and a device for making a catalyst layer of fuel cells, which belongs to an electricity generator and belongs to the field of the covering of vacuum evaporating metallic materials. The purpose of the present invention is to solve the problems of low efficiency and high cost caused by discontinuous production with the existing cathode sputtering making method. The metal on a metallic catalyst layer is made into two metal wires which are in a short circuit state by a power supply to be used as an evaporator source under the condition of vacuum degree not less than 1*10<-4>Pa. Thus, the evaporated gaseous metal can be attached to carbon paper which is arranged just at the evaporating height distance above the evaporated gaseous metal, is capable of continuously moving and has the condensation temperature between-5 DEG C and 15 DEG C. Thus, the catalyst layers Pt/C and Pt. Ru/C of fuel cells are made. Compared with the existing vacuum cathode sputtering method, the vacuum evaporating method realizes continuous manufacture and short production time, greatly raises production efficiency, lowers cost by 99 percent and ensures basically same evaporating quality, evaporating thickness and adhesion. The vacuum evaporating device independently designed by the present invention has the cost of only one tenth of the imported vacuum evaporating device. Therefore, the present invention provides conditions for mass production and promotes quick development of the fuel cells. The fuel cells can be used for the power supply of automobiles, submarines, satellites, airships, etc.

Description

Method and apparatus for making fuel cell catalyst layer

The technical field is as follows:

the invention relates to a method and a device for manufacturing a fuel cell catalyst layer, belonging to a method or a device for directly converting chemical energy into electric energy (H01M) and a method for coating a metal material by a vacuum evaporation method (C23C).

(II) background technology:

the fuel cell is a high-efficiency pollution-free power generation device, and directly converts chemical energy in stored fuel and oxidant into electric energy. Can be used as power supply for automobile, submarine, satellite and airship.

The main parts and principles of the fuel cell are as follows: see fig. 2, with flow field electrodes with gas flow 12a (anode) and 12b (cathode); anode catalyst layer 1c and cathode catalyst layer 1d, electrolyte 11, hydrogen as fuel (entering through anode inlet 13 a), air and pure oxygen as oxidant (entering through cathode inlet 14 a), gas and water being removed through anode outlet 13b and cathode outlet 14 b. Hydrogen gas is subjected to electrode reaction under the action of catalyst ( ) Electrons are generated (e) to the cathode via an external circuit, hydrogen ions are generated to the anode via the electrolyte, and oxygen, hydrogen ions and electrons are reacted at the cathode to generate water (1/2O)₂+2H+2e----H₂O), the water produced does not dilute the electrolyte but is discharged with the reaction off-gas through the electrodes.

The existing fuel cell has the following 6 types according to different electrolytes, namely ① alkaline oxyhydrogen fuel cell (AFC) ② regenerated oxyhydrogen fuel cell fuel (RFC) ③ molten carbonate fuel cell (NCFC) ④ Proton Exchange Membrane Fuel Cell (PEMFC) ⑤ Direct Methanol Fuel Cell (DMFC) ⑥ fixed oxide fuel cell (SOFC) which has new technology, high cost, unstable part process and realization of commercialization, scientific and technical personnel of various countries develop and improve, in 1983, Canada develops a perfluorinated proton sulfonic acid membrane (Nafion), DuPont company commercializes, and simultaneously adopts platinum/carbon catalyst and realizes the integration of cathode, anode and membrane hot pressing into a 'three-in-one' main part MEA.

The catalyst layer is an important part of the fuel cell, and the existing catalyst layer is prepared by ① colloid gel method, Proto tech 1997 patent (U.S 4044193), ② ion exchange method ③ H₂PcClb direct reduction method: in Chinese patent ZL99112700.5 of institute of Physics and chemistry of Chinese academy of sciences, a method for directly using H is provided₂The catalyst layers prepared by the three early preparation methods have uneven dispersion, the platinum loading exceeds 0.3mg/cm, and the catalyst layers can not be used for production practice ④ vacuum cathode sputtering method, which is a successful physical method, 99.9 percent of platinum sheet is used as a sputtering target (cathode) in vacuum, a carbon paper diffusion layer is used as an anode, the sputteringvoltage is 3000 volts, and the sputtering vacuum degree is controlled to be 5 multiplied by 10^-5Pa, according to scanning electron microscopy and energy-general analysis: the platinum loading is 1/5 of the above three methods of 0.3Mg/cm, which is very platinum material saving. The performance of the fuel cell was stable when the operation was performed according to the assembled fuel cell. However, the greatest disadvantage of the vacuum cathode sputtering method is that continuous production cannot be performed, and sputtering can be performed in vacuum only one by one (vacuum sputtering is performed one by one at a time), which results in low production efficiency and high cost.

(III) the invention content:

the invention provides a method and a device for manufacturing a fuel cell catalyst layer, which solve the problems of low efficiency and high cost caused by the fact that the existing cathode sputtering manufacturing method for manufacturing the fuel cell catalyst layer cannot continuously produce.

The technical scheme is as follows:

the method for manufacturing the fuel cell metal catalyst layer is characterized by comprising the following steps of: under vacuum degree of not less than 1 × 10^-4Under the condition of Pa, two metal wires made of the same metal of the metal catalyst layer are short-circuited by a direct-current power supply to be used as an evaporation source, so that evaporated gaseous metal is attached to a position which is arranged right above the evaporation source and has the evaporation height h, can continuously move and has the condensation temperature of-5 to-15 DEG COn carbon paper.

The moving speed V of the carbon paper can be 7-8 m/min, and can be selected according to the thickness of the catalystlayer. The evaporation height h can be adjusted and can be selected according to the power of the fuel cell. The catalyst metal may be platinum alone or platinum plus ruthenium

The preparation method can be carried out according to the following steps:

① placing carbon paper 6 required for catalyst layer on two carbon paper rollers, adhering the top of carbon paper to the bottom plate of condenser, connecting two metal wires 1b fixed to the positive and negative electrodes of DC power supply U0, placing the two metal wires 1a on roller 3, setting their ends in crucible to form evaporation source, regulating evaporation height h, ② starting vacuum evaporator to make its vacuum degree not lower than 1 × 10^-4Pa, ③ starting condenser to make its carbon paper temperature within-5-15 deg.C, ④ starting DC power supply U0 and the drive motor of metal wire roller, the roller 3 rotating to connect the metal wire 1a and 1b, ⑤ starting the drive motor of carbon paper roller to drive the carbon paper to move, ⑥ two short-circuited metal wires quickly heating to melting point to become gaseous ions, moving upwards to attach to the condensing carbon paper.

The device used by the manufacturing method comprises the following structural characteristics:

a crucible is arranged on the inner bottom surface of the vacuum evaporator, and a bolt with adjustable evaporation height h is arranged on the bottom surface; a condenser is arranged right above the crucible, and the bottom plate of the condenser is arc-shaped and is the same as the arc of the carbon paper; copper pipes are welded in the bottom plate and communicated with an external evaporator for introducing cooling medium; the condenser is fixed on the shell by a connecting piece; an isolation baffle is arranged in the range of the evaporation height h; the carbon paper winding roller is driven by a stepless speed regulating motor; insulation is arranged between the metal wire winding roller and the rotating shaft.

The invention has the beneficial effects that: i. compared with the vacuum cathode sputtering process, the vacuum evaporation method realizes the continuous manufacture of the catalyst layer, has short production time, greatly improves the production efficiency and reduces the cost by 99 percent. The evaporation quality, evaporation thickness, adhesion and the like are basically the same. The self-designed vacuum evaporator of the present invention has a cost of 1/10 for existing import equipment. Vacuum requirements are an order of magnitude lower than sputtering processes. And iv, the operation is more convenient. v. the invention provides conditions for mass production, which will promote commercialization and rapid development of fuel cells.

(IV) description of the drawings:

FIG. 1 is a schematic diagram of the method, principles and apparatus of the present invention

FIG. 2 is a schematic diagram of the main part of a fuel cell

(V) specific embodiment:

referring to fig. 1, a method for manufacturing a proton exchange membrane (also called as a perfluorinated proton sulfonic acid membrane) fuel cell metal catalyst layer adopts the following vacuum evaporation method: under vacuum degree of not less than 1 × 10^-4Under the condition of Pa, two platinum wires made of the same metal platinum of the metal catalyst layer are short-circuited by a direct current power supply to be used as an evaporation source, so that evaporated gaseous platinum is attached to carbon paper which is arranged right above the evaporation source and has the evaporation height h, can continuously move and has the condensation temperature of-5 to-15 ℃. The catalyst layer Pt/C is prepared and can be used as the cathode catalyst layer 1d (see fig. 2).

The preparation method comprises the following steps:

① in a vacuum evaporator 10, the carbon paper 6 needed by the catalyst layer 1c is arranged on two end winding rollers 7 and 8, the arc surface above the carbon paper is clung to the arc surface of a bottom plate 9.1 of a condenser 9, meanwhile, one of platinum metal wires 1a needed by the catalyst layer 1c is arranged on a winding roller 3, the other platinum metal wire 1b is fixed, the two metal wires are respectively connected with the positive and negative electrodes of a direct current power supply for short circuit, the voltage U0 is set to be 1.5-2V, the short circuit current is preset to be 100 and 200 amperes, the ends of the two metal wires can be simultaneously arranged in a crucible 4, thereby forming an evaporation source, the evaporation height h is adjusted as required, a baffle plate 5 is arranged at the position, ② starts an external vacuum pump 10.1 of the vacuum evaporator 10 or simultaneously starts a diffusion pump 10.2 as required, so that the internal vacuum degree is not lower than 1 multiplied by^-4Pa, ③ starting evaporator 9.3 at the outside of condenser 9 to gasify Freon or lithium rustide as the cooling mediumThe carbon paper is introduced into copper tubes 9.2 welded and distributed on a bottom plate 9.1, the carbon paper absorbs heat circularly to cool the carbon paper 6, the temperature reaches about-10 ℃, the carbon paper is adsorbed on the surface of the bottom plate, ④ starts a direct current power supply U0 and a driving motor of a winding roller 3, the winding roller 3 rotates to transfer a platinum wire 1a to be short-circuited with a platinum wire 1b, ⑤ simultaneously starts a winding roller 7 and a driving motorwith 8 stepless speed regulation to drive the carbon paper 6 to move slowly, the moving speed V can be selected according to the thickness delta of a catalyst layer, generally, the V can be 7.5 m/min, two platinum wires short-circuited with ⑥ quickly rise in temperature to reach a melting point to form gaseous ions, the gaseous ions move upwards to be attached to the continuously advancing and condensed carbon paper 6, and thus a catalyst layer platinum/carbon (Pt/C)1d (shown in the figure 2) which is firmly attached to an integrated catalyst layer is prepared, if a platinum/carbon layer (PtRu/C) which is a bimetallic catalyst layer is prepared, the platinum layer can be used as an anode catalyst layer (shown in the figure 2), and.

① vacuum evaporator 10, the shell 10.3 is made of stainless steel, the shell is equipped with vacuum pump 10.1 or diffusion pump 10.2 according to need, ② vacuum evaporator is equipped with crucible 4 on the bottom and bolt 4.1 which can adjust crucible height (evaporation height h) on the bottom, ③ condenser 9 on the top of vacuum evaporator, its bottom plate 9.1 is arc shape same as carbon paper, copper tube 9.2 is welded in the bottom plate and connected with evaporator 9.3 outside, to feed in freon 9.4, condenser 9 is fixed on the shell 10.3 by connecting piece 9.5, isolation baffle 5 is installed in the evaporation height h range of ④ vacuum evaporator to prevent metal gas ion diffusion, stainless steel is used, ⑤ vacuum evaporator is equipped with carbon paper speed regulating roller 7 and 8 driven by stepless motor, to conveniently and smoothly regulate carbon paper speed, ⑥ metal wire winding roller 3 and rotating shaft are all equipped with insulation.

Claims

1. The method for manufacturing the fuel cell catalyst layer is characterized by comprising the following steps of: under vacuum degree of not less than 1 × 10^-4Under the condition of Pa, two metal wires made of the same metal of the metal catalyst layer are short-circuited by a direct-current power supply to be used as an evaporation source to evaporateThe gaseous metal is attached to the carbon paper which is arranged right above the carbon paper and has the evaporation height h, can move continuously and has the condensation temperature of-5-15 ℃.

2. The method of producing a catalyst layer according to claim 1, wherein the carbon paper is moved at a speed V of 7 to 8 m/min.

3. The method for producing a catalyst layer as claimed in claim 1, wherein the evaporation height h is adjustable.

4. The method of claim 1, wherein the catalyst metal is platinum alone or platinum plus ruthenium.

5. A method for producing a catalyst layer according to claim 1, 2 or 3, characterized in that the production method comprises the steps of:

① placing carbon paper required by catalyst layer on carbon paper winding rollers at both ends, attaching the top of the carbon paper to the bottom plate of condenser, connecting two wires of the same metal required by the catalyst layer to the positive and negative electrodes of DC power supply U0, respectively, fixing one (1b) and the other (1a) on the winding rollers, placing the ends of the two wires in crucible to form evaporation source, adjusting evaporation height h according to battery power, ② starting the vacuum evaporator to make its vacuum degree not lower than 1 × 10^-4Pa, ③ starting condenser tomake carbon paper temperature within-5-15 deg.C, ④ connecting DC power supply U0 and driving motor for starting metal wire roller, the roller (3) rotating to transfer metal wire (1a) and short circuit with metal wire (1b), ⑤ starting driving motor for carbon paper roller (7) and (8) to drive carbon paper to move, ⑥ two short-circuited metal wires quickly heating to melting point to become gaseous ion, and moving upward to attach to continuously advancing condensed carbon paper.

6. The apparatus for manufacturing a catalyst layer according to claim 5, wherein the apparatus comprises the following structure: