A Study On Modified Polybenzimidazoles As High Temperature Proton Exchange Membrane Materials

In order to expand the proton exchange membrane fuel cell applications and reduce fuel cell system cost, the research of new proton exchange membranes for high temperature operation has become a research hotspot in recent years. Nowadays, polybenzimidazole (PBI) phosphoric acid (PA) proton exchange membrane, due to its excellent thermal stability and mechanical properties, has became the most successful high-temperature proton exchange membrane.However, as PBI chain contains several benzenes and hydrogen bonds between its chains, which resulting poor solubility of PBI, is difficult to process and apply large-scale commercial production.In this study, we used new monomer to prepare a polybenzimidazole(BuIPBI) which containing large alkyl groups to improve the solubility in organic solvent. Meanwhile we introduced graphite oxide (GO) and modified graphite oxide (iGO) to further enhance the BuIPBI proton conductivity through a variety of means. The major research contents of this essay are as follows:(1) Using new monomer to prepare a polybenzimidazole(BuIPBI) containing large alkyl groups to improve the solubility in organic solvent such as DMAc; and prepared BuIPBI proton exchange membrane with a series of tests, and the conductivity of BuIPBI membrane is11.4mS cm-1(2) Successfully prepared graphite oxide (GO) by modified Hummer method, and prepared a series of GO/BuIPBI proton exchange membranes. The proton conductivityof GO/BuIPBI membranes can reach to16.0mS cm-1, which is40%higher thanthe BuIPBI membrane;(3) Using tert-butyl isocyanate to modify GO and successfully prepared modified graphite oxide (iGO), and prepared a series of iGO/BuIPBI proton exchange membranes.The proton conductivity of iGO/BuIPBI membranes can reach to38.0mS cm-1, which is140%higher thanthe BuIPBI membrane;...