Improving Nafion/zeolite nanocomposite with a CF3SO3- based ionic liquid for PEMFC application

Abstract

Nafion/zeolite/ionic liquid composite membranes were prepared by the casting method. A fixed 3 wt% of the HZSM-5 zeolite was added to the polymer as well as the C16MI.CF3SO3 ionic liquid (IL) in various amounts in the range 6–30 wt%. The presence of zeolite and the IL in the Nafion matrix improved water absorption and proton conductivity and retained thermal stability when compared to the pure Nafion membrane (ND2020). The composite membrane, containing 5 wt% IL (N/HZ/IL-0.5), showed protonic conductivity two and half times higher than the pure Nafion. The composite membranes were tested in a single proton exchange membrane fuel cell (PEMFC) operating at 80 °C and 100 °C under low humidity conditions. The PEMFC test results indicated that the N/HZ/IL-0.5 composite membrane was the most stable material and showed better performance than the ND2020 membrane at 100 °C. The N/HZ/IL-0.5 sample showed a power density and current density approximately 200% higher than the pure Nafion membrane. These results indicate that the N/HZ/IL-0.5 composite is a material particularly well-suited to be used in PEMFC membranes operating at temperatures close to 100 oC.