Enhanced alkaline stability and performance of alkali-doped quaternized poly(vinyl alcohol) membranes for passive direct ethanol fuel cell

Direct ethanol fuel cells (DEFCs) emerge as the new research energy field since fast production of electricity, high efficiency conversion, and simple fabrication process. The production cost, conductivity properties, and ethanol permeability of membrane were the main problem that limited the DEFC performance and commercialization. In this study, a low cost, good ionic conductivity and low ethanol permeability of an anion exchange membrane based on incorporation KOH-doped quaternized poly(vinyl alcohol) (QPVA) membrane (designed as QPVA/KOH) is synthesized and cross-linked with glutaraldehyde solution. The membrane is expected to cut the production cost and enhance the performance. In this work, an optimum of alkali-doped concentration has influence the membrane performance. The membrane has reveal high chemical stability even doped with 8-M KOH solution in 100 degrees C. The morphology of membranes remained unbreakable and achieved high range of ionic conductivity (similar to 10(-2) S cm(-1)). The membranes present maximum ionic conductivity 1.29 x 10(-2) S cm(-1) at 30 degrees C and 3.07 x 10(-2) S cm(-1) at 70 degrees C. The ethanol permeability of membrane is lower compared with the commercial membranes. Power density of alkaline DEFCs with platinum-based catalyst by using cross-linked QPVA/KOH membrane is 5.88 mW cm(-2), which is higher than commercial membranes at 30 degrees C temperature. At 70 degrees C, power density has increased up to 11.28 mW cm(-2) and significantly increased up to 22.82 mW cm(-2) via the nonplatinum-based catalyst. Moreover, according to the durability test, the performance of passive alkaline DEFC by using cross-linked QPVA/KOH membrane has maintained at 36.2% level. With such efficiency, the stack current density has been able to stay above 120 mA cm(-2) for over 1000 hours, at 70 degrees C.