Sun, Hong-Xu, Fu, Yao-Mei, Meng, Xing, Wang, Hai-Ning, He, Yu-Ou, Yang, Rui-Gang, and Su, Zhong-Min
Development of new proton exchange membranes for fuel-cells draw considerable attentions. A family of proton conductive membranes based on poly(sodium 4-styrene sulfonate) (PSSNa) and polyvinylidene fluoride (PVDF) combining with various additives oxalic acid (OX), phosphate (PA) and phosphomolybdic acid H 3 PMo 12 O 40 ·XH 2 O (PMo 12) have been fabricated through a slurry casting approach, and are defined as PSSNa-PVDF-OX, PSSNa-PVDF-PMo 12 and PSSNa-PVDF-PA respectively, whose proton conductivities have been systematically investigated. Among them, PSSNa-PVDF-OX shows the superior proton conductivity, compared to PSSNa-PVDF-PA and PSSNa-PVDF-PMo 12 , and the best proton conductive value can reach up to 5.0 × 10−3 S cm−1 at 60 °C and 95% relative humidity, proving the good compatibility of OX with PSSNa and PVDF, giving birth to an effective proton transport channel. In order to demonstrate the role of Na+, poly(4-styrene sulfonic acid) (PSSA) is employed to replace PSSNa, generating another series of proton conductive membranes PSSA-PVDF-OX. The proton conductivity of PSSNa-PVDF-OX is greater than those of PSSA-PVDF-OX, which is attributed to the strong interactions between Na+ and water molecules, accelerating proton movement. Summarily, the enhanced conductivity is attributed to the generated efficient conduction pathways constructed from Na+ ions, water molecules, abundant -COOH from OX and -SO 3 - groups from PSSNa as well as rich F groups from PVDF. Several proton-conductive membranes are prepared with the best value of 5.0 × 10−3 S cm−1, demonstrating Na+ play an important role for high proton conduction. [Display omitted] • A series of composite membranes with various additives based on PSSNa and PVDF have been synthesized. • PSSNa-PVDF-OX60 shows superior performance and the best proton conductive value is 5.0 × 10−3 S cm−1 at 95% RH and 60 °C. • The introduction of Na+ builds the efficient transfer pathway for protons with OX, water as well as polymers. [ABSTRACT FROM AUTHOR]