Improved electrochemical performance of composite anion exchange membranes for fuel cells through cross linking of the polymer chain with functionalized graphene oxide
2020
Chu, Ji Young | Lee, Kyu Ha | Kim, Ae Rhan | Yoo, Dong Jin
Novel anion conductive nanocomposite membranes with superb hydroxide conductivity and chemical durability in alkaline conditions were prepared by the introduction of quaternary ammonium functionalized graphene oxide (Q-GO) into quaternized poly(arylene ether) (QPAE) random copolymer. Q-GO containing amino silane units, which induce ion cluster formation in the polymer matrix, was synthesized using (3-aminopropyl)triethoxysilane (APTS) and (3-bromopropyl)trimethyl ammonium bromide (PTMA) as the main quaternization reagents. The chemical structures and morphologies of the polymers and inorganic nanofillers were characterized by ¹H NMR, FT-IR, FE-SEM, XPS, and SAXS. GO-(APTS-c-PTMA), the so called Q-GO, was used to expand the ion transfer sites and improve the physicochemical stability of the membrane. The electrochemical properties, thermal/mechanical properties, and chemical stabilities of the anion exchange membranes (AEMs) were investigated in accordance with different contents of GO-(APTS-c-PTMA). The π-π bonds between the polymer matrix and the Q-GO resulted in improved dimensional stability and mechanical properties in the composite membrane. The QPAE/GO-(APTS-c-PTMA) 0.7 wt% membrane showed the highest hydroxide conductivity of 114.2 mS cm⁻¹ at 90 °C with an ion exchange capacity of 1.45 mmol g⁻¹, which is 2.07 times higher than the pristine membrane (55.1 mS cm⁻¹ at 90 °C). Furthermore, the single-cell performance of the QPAE/GO-(APTS-c-PTMA) 0.7 wt% as an AEM showed an excellent maximum power density of 135.8 mW cm⁻² at 70 °C.
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