Polybenzimidazole (PBI)-functionalized silica nanoparticles modified PBI nanocomposite membranes for proton exchange membranes fuel cells

Polybenzimidazole (PBI) has been chemically bonded to silica nanoparticles (SNPs) through an ozone-mediated process using N-(p-carboxyphenyl)maleimide (pCPM) functionalized SNPs (SNP-pCPM) as precursors, to enhance the interfacial compatibility between SNPs and PBI in PBI/SNP nanocomposites. The PBI-functionalized SNPs (SNP-PBI) have been well characterized and used as inorganic nanofillers for preparation of PBI/SNP-PBI membranes for fuel cells. Addition of PBI-SNP to PBI membranes enhances their thermal and mechanical properties as well as decreases their phosphoric acid uptakes. For the PBI/SNP-PBI membrane with 10 wt% of SNP-PBI, it shows a proton conductivity of about 50 mS cm−1 at 160 °C, which is 25% higher compared to the pristine PBI membrane. Consequently, the PBI/SNP-PBI membrane demonstrates a maximum power density of 650 mW cm−2 in a single cell test, compared to the value of 530 mW cm−2 read from the test for pristine PBI membrane.