Enhanced conductivity and stability of composite membranes based on poly (2,5-benzimidazole) and zirconium oxide nanoparticles for fuel cells

Poly (2,5-benzimidazole) (ABPBI) and zirconium oxide (ZrO₂) nanoparticles composite membranes were synthesized. These membranes can be fabricated into tough, dense membranes by blending Poly (2,5-benzimidazole) (ABPBI) with zirconium oxide (ZrO₂) nanoparticles, which were characterized by using FTIR, XRD, SEM, TGA, DSC and tensile test. These composite membranes showed increased conductivity compared with original ABPBI membrane. Maximum proton conductivity at 100 °C was found to be 0.069 S cm⁻¹ on 10% ZrO₂ incorporated ABPBI composite membrane, almost four times as high as the 0.018 S cm⁻¹ obtained in the case of the ABPBI membrane. The conductivity was 0.0325 S cm⁻¹ at 180 °C in dry condition for ABPBI with 10% ZrO₂ nanoparticles composite membrane, higher than the conductivity 0.011 S cm⁻¹ of the ABPBI membrane at same condition. Furthermore, the composite membranes were shown to have high thermal and mechanical stability. These results suggest that ABPBI/ZrO₂ composite membranes may be a promising polymer electrolyte for fuel cells at medium or high temperature, due to their strong physical properties.