Influence of mesoporous fillers on performance of high–temperature proton exchange membrane fuel cell

• Main Authors: Ying–Chieh Kuo, 郭英傑
• Other Authors: Hsiu–Li Lin
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/4s4kq3

博士 === 元智大學 === 化學工程與材料科學學系 === 107 === The incorporation of nanoscale additives in polybenzimidazoles (PBI) membranes is an effective way of simultaneous increasing the proton conductivity and improving the mechanical stability of the membranes during acid doping, as well as increasing their reliability with respect to membrane electrode assembly (MEA) fabrication. In this study, we tried to study the principle of mesoporous fillers on the performance of high–temperature proton exchange membrane fuel cell, and tried to observe the effects of different mesoporous filler materials on the performance of high–temperature proton exchange membrane fuel cells. In the first part of the study, we elucidated the effects of the addition of various mesoporous silicates (0–20 wt%) to the membranes used for high–temperature proton exchange membrane fuel cells (HT–PEMFCs) on cell performance. Two types of PBI–based hybrid membranes were prepared by homogeneously dispersing a predetermined amount of MCM-41 or SBA-15 within the PBI matrix. Compared to the pure PBI membrane, those with MCM-41 and SBA-15 exhibited significantly enhanced phosphoric acid doping and better mechanical properties, leading to improved HT–PEMFC performance and reduced acid migration. However, the membranes with 20 wt% silicate showed inferior performance compared to those with 10 wt% silicate. In addition, the membranes with SBA-15 exhibited noticeable aggregation, lower phosphoric acid doping, and greater phosphoric acid migration during the leaching test than did the membranes with MCM-41. Finally, during the short–term test, the PBI/MCM-41 (10 wt%) membrane showed the best performance (maximum power density of 310 mW cm–2 at 180 C). In the second part of the study, we investigated the effect of immersion times for PBI, PBI / MCM-41 and PBI / SBA-15 membranes in 85 wt% phosphoric acid solution on phosphoric acid the doping amount (PA dop) and proton conductivity. Through previous tests, we found that PBI / MCM-41 (10 wt%) membranes have the highest PAdop and the lowest degree of acid leaching (Dal). We combine PBI / MCM-41 (10 wt%) membrane and electrodes to create an MEA for high temperature PEM fuel cell (HT–PEMFC) applications. The electrical resistance, AC impedance, high–temperature PEM fuel cell performance, and short–term single–cell performance test were measured. The results showed that the PBI / MCM-41 (10% wt%) membrane impregnated with phosphoric acid for 20 h what is the PAdop was showed the best performance maximum power density (391 mW•cm–2 at 180 C) in short–term fuel cell tests.