The study on the fabrication of the micro-pillard structure electrode of a PEMFC

• Main Authors: Wu-syuan Lee, 李武軒
• Other Authors: Lee, Ming-San
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/8u2e6a

碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 95 === Abstract The conventional hydrophilic electrode used to spray the catalyst on the level-off carbon layer and the utilization of catalysts can only be reacted between the gas and the catalyst; however, the internal catalyst of the proton exchange membrane cannot be reacted. In order to increase the reaction of the catalyst, the hydrophobic pillared micro structures (HPMS) are made on the carbon layer, so that the gas can reach the catalyst in the internal membrane so that a reaction on large surface between the gas and the catalyst can be achieved. It is easier to build the gas channel in the internal HPMS than the structures of the carbon layer. As a result, more gas can be sent to the internal catalyst thus enlarging the reaction zone and more reactions between the gas and the catalyst is then achieved. The carbon powder is sprayed in the conventional HPMS in the deposition process. The HPMS are formed after the gravity process while the powder is passing the metal netmask and the manufacturing time is long. The experimental design uses electroforming to make the micro porous structure so that the hydrophobic carbon layer can be stamped thereby forming the HPMS. It has been proven that the time for the manufacturing process can be shortened if the micro structured metal template is applied. The micro structured metal template is used to stamp the small and large HPMS on the side electrode of the cathode, the stamping HPMS pressure was 500kg/cm2. With the same catalyst quantity the surface of the small HPMS was raised 63% and its performance was up to 55%; the surface of the large HPMS was raised 30% and its performance was up to 30%. The catalyst quantity of the cathode was reduced from 0.5mg/cm2 to 0.25 mg/cm2 and its performance remains the same. The experiment’s results indicate that the reaction of the catalyst was only on the surface between the gas and the catalyst. Either small or large HPMS or after reducing the catalyst quantity can all raise the performance of the fuel cell as well as economize the catalyst. And by two kind of different size dimension microstructure metal template manufacture small or large HPMS, the electrode power density all may achieve 720mW/cm2 and 595mW/cm2.