Advantages of a Polyimide Membrane Support in Nonhumidified Fluorohydrogenate‐Polymer Composite Membrane Fuel Cells

Abstract We have successfully prepared composite membranes consisting of the ionic liquid N ‐ethyl‐ N ‐methylpyrrolidinium fluorohydrogenate and the polymer 2‐hydroxyethylmethacrylate and have secured them on a polyimide (PI) membrane support. The resulting EMPyr(FH) 1.7 F–HEMA (9:1 molar ratio) composite possesses ionic conductivity of 75 mS cm −1 at 120 °C when a 16‐µm support is employed, showing improved performance with elevated temperature; this marks a significant difference from devices using conventional polytetrafluoroethylene supports. In the single cell test, a maximum power density of 31 mW cm −2 is observed at 120 °C. Cross‐sectional SEM images of the corresponding membrane electrode assemblies reveal no significant difference in membrane thickness before and after cell testing, implying that this support does not suffer from membrane softening issues.