Porous substrate-reinforced composite membranes for proton exchange membrane fuel cells (PEMFC) have drawn a great deal of attention due to their strong potential for commercialization. In this study, we develop a new reinforcing substrate based on a SiO2 nanoparticle-coated polyimide (PI) nonwoven. This substrate features low thickness, high porosity, and strong affinity for water-swollen proton conducting polymers such as Nafion®. SiO2 nanoparticles, which are interconnected by polyetherimide (PEI) binders, are introduced for the purpose of improving the mechanical strength and hydrophilicity of the electrospun PI nonwoven. The increased polarity of the nonwoven substrate is expected to allow for facile impregnation of a hydrophilic Nafion solution. In contrast, the pristine, hydrophobic PI nonwoven substrate shows very poor affinity with Nafion, and consequently fails to produce a Nafion-impregnated composite membrane. Based on this understanding of the porous substrates, the effects of the SiO2/PEI-coated PI nonwoven substrate on dimensional change and proton conductivity of a Nafion-impregnated composite membrane are investigated. A noteworthy finding is that in addition to suppressing the dimensional change, the composite membrane is effective in retarding the steep decline of proton conductivity at low humidity conditions owing to the presence of the SiO2/PEI-coated PI nonwoven substrate, which is discussed in greater detail with consideration of the state of water in the membrane.
Bibliographical noteFunding Information:
This work was supported by the New and Renewable Energy R&D program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy ( 2008-N-FC12-J-01-2-100 ). This research was also supported by a grant from the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Knowledge Economy. This work was also supported by National Research Foundation of Korea Grant funded by the Korean Government (2009-0066986).
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Physical and Theoretical Chemistry
- Filtration and Separation