Blended Nafion ®/SPEEK direct methanol fuel cell membranes for reduced methanol permeability

• Published in: Journal of power sources Vol. 189; no. 2; pp. 958 - 965
• Main Authors: Tsai, Jie-Cheng, Cheng, Hui-Pin, Kuo, Jen-Feng, Huang, Yao-Hui, Chen, Chuh-Yung
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.04.2009; Elsevier
• Subjects: Applied sciences; Blend; Direct methanol fuel cell; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fuel cells; Methanol permeability; Nafion; Proton exchange membrane; Sulfonated poly(ether ether ketone); Methanol permeability; Direct methanol fuel cell; Proton exchange membrane; Sulfonated poly(ether ether ketone); Nafion; Blend; Power density; Thermal decomposition; Alcohol fuel cells; High temperature; Permeability; Open circuit voltage; Sulfuric acid; Proton conductivity; Membrane; Sulfonation; Performance; Methanol
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2008.12.071

Sulfonated poly(ether ether ketone)s (SPEEKs) were substituted on a polymer main chain that had previously been prepared by sulfonation of poly(ether ether ketone)s in concentrated sulfuric acid for a specified time. The product was then blended with Nafion ® to create composite membranes. The blended SPEEK-containing membranes featured flaky domains dispersed in the Nafion ® matrix. These blends possessed a high thermal decomposition temperature. Additionally, owing to the more crystalline, the blended membranes had a lower water uptake compared to recast Nafion ®, the methanol permeability was reduced to 1.70 × 10 −6 to 9.09 × 10 −7 cm 2 s −1 for various SPEEK concentrations, and a maximum proton conductivity of ∼0.050 S cm −1 was observed at 30 °C. The single-cell performances of the Nafion ®/SPEEK membranes, with various SPEEK concentrations and a certain degree of sulfonation, were 15–25 mW cm −2 for SPEEK53 and 19–27 mW cm −2 for SPEEK63, at 80 °C. The power density and open circuit voltage were higher than those of Nafion ® 115 (power density = 22 mW cm −2). The blended membranes satisfy the requirements of proton exchange membranes for direct methanol fuel cell (DMFC) applications.