Development of polymer electrolyte membranes for fuel cells to be operated at high temperature and low humidity

Polymer electrolyte membrane fuel cells (PEMFCs) have been looked as potential alternative energy conversion devices to conventional energy conversion systems such as combustion engines. Proton conducting membranes (PEMs) are one critical component of PEMFCs. The development of novel electrolyte membranes with dense structure, good mechanical flexibility, and high proton conductivity, but with little or no dependence on humidity at temperatures above 100¡ãC remains an important challenge to the realization of practical PEM fuel cells. In this thesis, to solve the technical difficulties existing in current high temperature PEM systems based on phosphoric acid and imidazole, a new type of proton conducting species 1H-1,2,3-triazole has been explored, and proved to have high proton conductivity and also enough electrochemical stability for fuel cell applications. In further experiments, effective methods have been developed to synthesize triazole derivatives and polymers. The properties of the synthesized polymers have studied and reported in this thesis. Preliminary computational simulations have also been performed to study the proton conducting mechanism to provide intrinsic information of the proton conducting process in 1H-1,2,3-triazole. In the final part, research works on other proton conducting species including H3PO4 and other heterocycles have been reported.Ph.D.Committee Chair: Wong, C.P.; Committee Co-Chair: Liu, Meilin; Committee Member: Barefield, Kent; Committee Member: Collard, David; Committee Member: Fahrni, Christop