3.4. Ionic conductivity
Ionic conductivity is believed to be a key property for anion exchange membranes applied in alkaline AEMFCs. Table 2 lists the ionic conductivities of the six OH form membranes at 30 C. The ionic conductivities of the six OH form membranes as a function of the temperature are shown in Figs. 3 and 4. Membrane A, B and C are based on the copolymer of [VBI]Br and styrene, and Membrane D, E and F are based on the copolymer of [VMI]I and styrene. It is found that at 30 C the ionic conductivities increase with the increasing content of imidazolium cation groups. This can be explained that the more imidazolium cation groups, the more OH charge carriers. Insufficient imidazole functional groups will lower the conductivity of the membrane whereas excess imidazole functional groups will lead to poor dimensional stability and mechanical properties of the membrane.