Anhydrous proton conductors based on polybenzimidazole/ionic liquids composites

In this work, two types of innovative proton exchange membranes containing dicationic and monocationic ionic liquids are developed for elevated temperature fuel cells applications under anhydrous conditions. The composite membranes based on polybenzimidazole (PBI) and dicationic ionic liquid 1,6-di(3-methylimidazolium) hexane bis (hexafluorophate) (PDC6) or monocationic ionic liquid 1-Butyl-3-methylimidazolium hexafluorophosphate (PMC4) are prepared with solution casting method. The analyses of the results demonstrate promising characteristics such as high proton conductivity of phosphoric acid (PA) doped PDC6 composite membranes in comparison with PA doped PMC4 and PA doped PBI membranes at high temperatures. The proton conductivity of 78 mS/cm is achieved for PA doped PDC6 composite membranes with PBI/ionic liquid mole ratio: 4 at 180 ºC under anhydrous condition.

Keywords:

Polybenzimidazole , polymer electrolyte membranes , proton conductivity , dicationic ionic liquid