The Preparation And Proton Conductivity Of The Hybrid Membranes Based On ZIF/SPEES

Proton exchange membrane is the key component in proton exchange membrane fuel cells, which plays a decisive role in the performance of the fuel cell. Currently, the commercial Nafion membrane is not conducive to large-scale commercial application for fuel cells, because it is diffcult to sythesize, and it is expensive, and it could produce fluorine pollution problems. Hence, new type of fluorine-free proton exchange membrane needs to be developed for promoting fuel cell commercialization process, which has high performance and low cost.Sulfonated poly (1,4-phenylene ether ether sulfone) (SPEES) with higher proton conductivity can be prepared by sulfonated post-processing of poly (1,4-phenylene ether ether sulfone) (PEES), but its physical and chemical properties, especially the stability is affected. Zeolitic imidazolate frameworks (ZIFs) have excellent physical and chemical properties, such as larger specific surface area, pore structure and function controllable.In this paper, SPEES are prepared via sulfonated post-processing of PEES, and then mix the SPEES with ZIFs which is synthesized by hydrothermal method, finally a series of ZIFs/SPEES hybrid membranes are obtained by solution casting method. Phase composition, microstructure and other physico-chemical properties of hybrid membranes are systematically investigated by using FTIR, XRD, SEM, TG, IEC, Water uptake test, Swelling test, Chemical stability test and Proton conductivity test. The results indicate that ZIF-8/SPEES-1 hybrid membrane which is synthesized by 42.2% sulfonation degree of SPEES and 1:100 ZIF-8/SPEES weight ratio begin to decompose at 300?, the swelling ratio of hybrid membrane is only 3.81% at 80? and takes 352 min to dissolve in Fenton solvent, suggesting that thermodynamics and chemical stability of hybrid membrane are strengthened. ZIF-8/SPEES-0.4 hybrid membrane is prepared by 0.4:100 ZIF-8/SPEES weight ratio, the proton conductivity of ZIF-8/SPEES-0.4 is 0.042 S·cm-1 at 80?,90% RH, greater than that of pure SPEES membrane(0.027 S·cm-1) at the same condition.Mixing ZIF-67 and SPEES with 52% sulfonation degree, the resulting membrane maintain good thermodynamic and chemical stability, and no obvious micro-phase separation. ZIF-67/SPEES-0.3 hybrid membrane is synthesized by 0.3:100 ZIF-67/SPEES weight ratio, the proton conductivity of ZIF-67/SPEES-0.3 can achieve 0.07 S·cm-1 at 80?,90% RH. Finally, compositing the graphite oxide(GO) which contains a large number of hydrophilic group to the above materials, the resulting membrane ZIF-67/GO/SPEES not only has higher proton conductivity, but also has higher chemical stability. What's more, the proton conductivity of ZIF-67/GO/SPEES-1 hybrid membrane which is synthesized by 1:100 weight ratio of ZIF-67/GO and SPEES is further improved to 0.084 S·cm-1 at 80??90% RH.