High performance cross-linked anion exchange membrane based on the aryl-ether free polymer backbones for anion exchange membrane fuel cell application

Anion exchange membrane fuel cells (AEMFCs) have attracted growing interests for favored oxygen reduction reaction (ORR) electrochemical kinetics and potential low cost in recent years, and development of high performance AEMs is always an urgent issue. In this work, a series of cross-linked AEMs with different diamine cross linkers and various degree of crosslink based on the aryl-ether free tri-block copolymer SEBS were prepared with the in-situ crosslinking method, and the FT-IR, XRF and EDS confirm the structures and the degree of crosslink of the AEMs. Moreover, the cross-linked AEMs demonstrated good mechanical properties and dimensional stability, and the tensile strength reached 18.43 MPa (ca. 4.5 times higher than that of the membrane without crosslink), and the swelling ratio of the cross-linked AEMs were only ca. 10%, which meet the requirement of the AEMFC application. In addition, the cross-linked AEMs demonstrated high ion conductivity at the relative low IECs and water uptake, and the results of the SAXS and TEM verified that the high conductivity was attributed to the good hydrophilic/hydrophobic phase separation microstructure. Furthermore, in the test of H2/O2 AEMFCs, the MEAs used the cross-linked membranes displayed good fuel cell performance, especially for the C4-CQASEBS membrane, and the fuel cell realized the peak power density of 585 mW cm-2 at 60 oC. The results indicated that the cross-linked AEMs based on the SEBS was a promising candidate material for fuel cell application.