High temperature proton exchange membrane fuel cells (HT-PEMFCs)

can be directly fed with reformed gas therefore simplify the hydro-thermal management

due to their strong CO resistance

which can effectively solve the problem of hydrogen source and help achieve the carbon peaking and carbon neutrality goals. As the core component of HT-PEMFCs

high temperature proton exchange membrane (HT-PEM) has attracted much attention in recent years

especially for the most promising phosphoric acid-doped polybenzimidazole (PAPBI) electrolyte membrane. PA-PBI has many advantages

such as high mechannical/thermal/chemical stability and anhydrous proton conductivity. However

these advantages are not outstanding enough and there are still many shortcomings of traditional PA-PBI: In terms of membrane performance and operating life time

the contradiction between high proton conductivity and high mechanical properties

easily damaged by thermal stress during operating and excessive phosphoric acid loss of PA-PBI

etc

. restrict the the full-scale application of traditional PA-PBI in HT-PEMFCs. Other defects like poor film-forming properties would influence the fabrication of PA-PBI membrane. This review article is aimed to summarize some research progresses on PA-PBI

including the synthesis of PBI molecular

preparation process of PA-PBI membrane

proton transport mechanism and the the methods for improving the performance and operating life time of PA-PBI membranes such as molecular structure modification

grafting

cross-linking

and organic-inorganic composite doping are mainly discussed and prospect the future development of PA-PBI electrolyte membrane. Although the commercial application of PAPBI in HT-PEMFCs is still a long way off

scientists are gradually narrowing this distance

especially in terms of balancing proton conductivity

mechanical properties and operating lifetime of PA-PBI for the best application point. At the same time

the research on how to increase the operating temperature of PA-PBI to further enhance the performance of HT-PEMFCs has gradually attracted attention. It is believed that the full-scale application of PA-PBI in HT-PEMFCs will become a reality in the near future.