Progress of phosphoric acid doped high temperature proton exchange membrane for fuel cells

High temperature proton exchange membrane fuel cells (HT-PEMFCs) have been considered as one of the most attractive power sources for portable devices, due to their high tolerance to CO, enhanced activity of the electrocatalysts and simplified water and heat managements. As the key component, high temperature proton exchange membranes (HT-PEMs) influence a lot on fuel cell performance and long term stability. In recent years, phosphoric acid (PA) doped HT-PEMs have been proved to be one of the most promising alternatives for HT-PEMFCs because of their high proton conductivity and great thermal stability. The major technical challenges of these PA doped HT-PEMs are that the increase of PA loading enhances proton conductivity while the mechanical properties significantly decrease and the PA leaching exacerbates, which limit their wide applicability in HT-PEMFCs. This monograph summarizes recent advances for PA doped HT-PEMs on the design of new polymer, physical modification, microstructure control and so on. These developments on fundamental theories and main technologies establish a good foundation for future research.