Preparation and performance of sulfonated polyimide/Nafion multilayer membrane for proton exchange membrane fuel cell

A novel and simple thermal imidization method is used to prepare the sulfonated polyimide/Nafion multilayer (NF-SPI-NF) membrane from sulfonated polyimide (SPI) and Nafion-containing solution (Na+ form). The NF-SPI-NF membrane is prepared by immersing a sulfonated poly(amic acid) (SPAA) membrane into the Nafion-containing solution followed by thermal imidization via solvent evaporation. This Nafion is firmly adhered to either side of the SPI membrane via thermal imidization. The prepared membranes are characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and proton conductivity. The membranes are immersed in Fenton's reagent at room temperature to test their oxidative stability and the durability of a single proton exchange membrane fuel cell (PEMFC) system. Analytical results show a marked improvement in NF-SPI-NF membrane stability by adding Nafion layer comparing with that of native SPI membrane. The performance of PEMFC with the NF-SPI-NF membrane is similar to that of PEMFC with the commercially available Nafion 212 at 70 °C.

► Nafion layer adheres to the surface of sulfonated polyimide membrane by thermal imidization via solvent evaporation.
► Nafion layer on either side of the SPI membrane have enhanced the oxidative stability.
► The adhesion between the catalyst electrode and multilayer (sulfonated polyimide/Nafion) membrane is very stable.