Development and Characterizaiton of Sulfonated Polyimide Membrane for Proton Exchange Membrane Fuel Cell Applications

Abstract

The developments of the proton exchange membrane fuel cells are introduced and synthesis and characterization of new sulfonated polyimides are described. 1,4,5,8- naphthaene-tetracarboxylic dianhydride (NTDA), 4,4’- iaminostilbene - 2,2’- disulfonic acid (DSDSA), and other common diamines, such as 4,4’- oxydianline (ODA), and 4,4’- methylene dianiline (MDA) were used to synthesize the sulfonated polyimide copolymer by using a one-step high temperature polymerization method. The sulfonation degree of the copolymers can be controlled by using different molar ratio of DSDSA to the common diamines. Flexible, brown-colored and mechanically strong membranes were successfully obtained. The membranes were characterized with Fourier transform infrared spectra, thermogravimetric analysis, differential scanning calorimetry, water uptake, ion-exchange capacity, proton conductivity measurements and mechanical tests. These results showed that the membranes had good thermal and mechanical stability and exhibited good performance when they were assembled into membrane electrode assemblies (MEAs). Fuel cell testing was performed. The SPI copolymer based MEA was tested under different hydrogen flow rates; it was also compared with the commercial Nafion® based MEA. The SPI membrane exhibited good performance compared to Nafion®.