Effect of Modification of Cathode Catalyst on the Performance of a Proton Exchange Membrane Fuel Cell

• Main Authors: Ciou,Huan-Jyun, 邱煥鈞
• Other Authors: Li,Ying-Jeng
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/84606337204605390110

碩士 === 明志科技大學 === 化學工程系碩士班 === 104 === Cathode catalyst composition of the membrane electrode assembly of a proton exchange membrane fuel cell was modified by addition of polytetrafluoroethylene and nano-sized carbon powder, respectively. The amounts of PTFE added were 0.5%, 1%, 2%, 4%, and 15%, respectively; while those of nano carbon were 1%, 4%, and 15%, respectively. The results show that at higher PTFE loading, the performance of the fuel cell membrane electrode assembly decreased significantly, especially at high temperature or low humidity conditions. It should be due to the non-conducting and hydrophobic nature of PTFE. At higher PTFE loading, not only the resistance of the MEA was increased but also water retaining ability was decreased which results in poor proton conductivity. In the case of low PTFE loading, it is helpful to the MEA performance at low temperature or high current operations. It is probably because at such operation conditions, water flooding is severe and the hydrophobic nature of PTFE is helpful. In the cases of nano carbon addition, it is found that MEA performance is always decreased regardless of the amounts of nano carbon added. Carbon supported platinum Pt/C itself is a good electronic conductor. The addition of nano carbon does not help its conductivity; while it dilutes the platinum concentration in the catalyst composition. Linear sweep voltammetry method was also employed for evaluating hydrogen crossover of the MEAs prepared by using different catalyst compositions in this study. Results show that the rate of hydrogen crossover is low and there is not obvious difference of hydrogen crossover among different MEA samples.