Ionic conductivity and thermal stability of room temperature molten salts perfluorosulfonic acid membranes for fuel cell application

摘要

The conductivity and the thermal stability of room temperature molten salt (RTMS) containing membrane have been investigated as a proton conductor under dry conditions. Perfluorosulfonic acid (PFSA) membranes in the exchange capacity range from 0.91 to 1.05 meq g(-1) and Polytetrafluoroethylene (PTFE) filter membranes were used as polymer matrices. 1-Ethyl-3-methylimidazolium his (trifluoromethylsulfonyl) imide, 1-ethyl-3-methylimidazolium trifluoromethanesulfortate, and 2-ethyl imidazolium tetrafluoroborate were used as RTMSs.The thermal stabilities of the PFSA/RTMS composite membranes were higher than that of PFSA and RTMS themselves, but that of the PTFE/RTMS absorbed membranes were the same as that of RTMS. The interaction between PFSAs and RTMSs enhances the thermal stability of the composite membranes. The ionic conductivities of the PFSA/RTMS composite membranes were in the range from 10(-5) to 10(-3) S cm(-1) at 120degreesC, and increase with temperature following the Arrhenius law. The conductivities of the RTMS absorbed PTFE membranes were greater than 10(-2) S cm(-1) at 120degreesC. The activity of the proton conduction media of these RTMSs is weaker than that of water but they were more stable under dry condition.