Investigation of direct methanol fuel cell performance of sulfonated polyimide membrane

Sulfonated polyimide (SPI) membranes have been evaluated as electrolyte membranes in direct methanol fuel cells (DMFCs). The membrane–electrode assembly (MEA) was made by hot-pressing the membrane, an anode and a cathode, catalyzed with PtRu/CB (PtRu dispersed on carbon black) and Pt/CB bound with Nafion® ionomer, respectively. The performance of the cell based on SPI was compared with that of Nafion® 112 in various operation conditions such as cell temperature (Tcell), cathode relative humidity (RH), and methanol concentration (CMeOH). The methanol crossover at the cell based on SPI was a half of Nafion® 112, resulting in the improved cell efficiency. Advantage of the use of SPI became much distinctive from the conventional Nafion® 112 when the DMFC was operated at a higher Tcell or a higher CMeOH.