質子交換膜燃料電池中陰極膜電極組製備與最佳化

• Main Authors: Wang Pei-Shan, 王珮珊
• Other Authors: Do Jing-Shan
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/11653069452833282577

碩士 === 東海大學 === 化學工程學系 === 95 === The effects of the hot pressing conditions and the cathodic compositions for preparing membrane electrode assemble (MEA) on the performances of proton exchange membrane fuel cell (PEMFC) were investigated in this thesis. First, the discharge characteristics of the fuel cell were studied by using traditional experimental method with the various hot pressing temperatures, pressures and times at fixed electrode compositions, and the optimum hot pressing conditions were studied by the Box-Behnken experimental design method. Based on the method of mixture design, the optimum cathodic compositions of Pt/C, Nafion® and PTFE were investigated by using the power densities of the fuel cell as response. The effect of the contents of the Nafion® in Pt/C-Nafion® and PTFE in Pt/C-PTFE on the performance of the fuel cell was also studied in this thesis. Increasing the hor pressing temperature from 110 to 160 oC resulted in the increase in the adhesion and the contact area between the MEA and Nafion® film, and then the power densities of the fuel cell from 208.00 to 249.28 mW cm-2 when the anodic and cathodic compositions were fixed at Pt/C: Nafion®: PTFE of 0.8: 0.1: 0.1 for the Pt loading of 0.4mg cm-2. Further increase in the hot pressing temperature to 180 oC the power densities of fuel cell decreased to 241.58 mW cm-2 because of the change in the morphology and properties of the proton exchange membrane. The power densities of fuel cell decreased from 208.00 to 144.83 mW cm-2 with increasing the hot pressing pressure from 10 kg cm-2 to 40 kg cm-2 due to the compression in the carbon fiber in the electrode caused the increase in the mass transfer resistance and the decrease in the active sites of electrode catalysts. For the relative short hot pressing time the lower discharge power densities of the fuel cell was deduced to be the less adhesion of the devices and the lower utilization of the catalyst, whereas in a longer hot pressing time due to the less porosity of the MEA resulted in the increase in the mass transfer resistance and the decrease in the discharge power density of fuel cell. The experimental results indicated that the power density of fuel cell increased from 177.25 mW cm-2 to the maximum value of 208.00 mW cm-2 with the increase in the hot pressing time from 1 to 2 min. The power density decreased to 188.63 mW cm-2 by further increase the hot pressing time to 7 min. Based on the Box-Behnken design method, the optimum hot-pressed conditions were obtained to be the hot pressing temperature, pressure and time of 160℃、10 kg cm-2 and 3 min, respectively, and the maximum power density was 319 mW cm-2. The optimum composition of the cathode obtained based on the method of mixture design was found to be Pt/C:Nafion®:PTFE = 0.72:0.16:0.12. The maximum power density of fuel cell was experimental obtained of 319 mW cm-2. For the binary composition of cathode the optimum contents of the Nafion® and PTFE in Pt/C-Nafion® and Pt/C-PTFE were 0.3 and 0.28, and the maximum power densities were obtained of 265 and 168.27 mW cm-2, respectively. According to the equivalent circuit developed in this thesis the impedances of the elements of analyzed by the AC impedance for the various MEAs prepared in this work were correlated well with the experimental results.