Investigation of sulfonated polysulfone membranes as electrolyte in a passive-mode direct methanol fuel cell mini-stack

• Published in: Journal of power sources Vol. 195; no. 23; pp. 7727 - 7733
• Main Authors: Lufrano, F., Baglio, V., Staiti, P., Stassi, A., Aricò, A.S., Antonucci, V.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.2010; Elsevier
• Subjects: Applied sciences; Density; Direct energy conversion and energy accumulation; Direct methanol fuel cells; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Electrolytes; Electrolytic cells; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fuel cells; Membranes; Methyl alcohol; Mini-stack; Optimization; Passive mode; Polymer electrolyte; Polysulfone resins; Sulfonated polysulfone; Uptakes; Sulfonated polysulfone; Polymer electrolyte; Direct methanol fuel cells; Passive mode; Mini-stack; Polymer electrolytes; Stacking; Alcohol fuel cells
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2009.11.130

This paper reports on the development of polymer electrolyte membranes (PEMs) based on sulfonated polysulfone for application in a DMFC mini-stack operating at room temperature in passive mode. The sulfonated polysulfone (SPSf) with two degrees of sulfonation (57 and 66%) was synthesized by a well-known sulfonation process. SPSf membranes with different thicknesses were prepared and investigated. These membranes were characterized in terms of methanol/water uptake, proton conductivity, and fuel cell performance in a DMFC single cell and mini-stack operating at room temperature. The study addressed (a) control of the synthesis of sulfonated polysulfone, (b) optimization of the assembling procedure, (c) a short lifetime investigation and (d) a comparison of DMFC performance in active-mode operation vs. passive-mode operation. The best passive DMFC performance was 220 mW (average cell power density of about 19 mW cm −2), obtained with a thin SPSf membrane (70 μm) at room temperature, whereas the performance of the same membrane-based DMFC in active mode was 38 mW cm −2. The conductivity of this membrane, SPSf (IEC = 1.34 mequiv. g −1) was 2.8 × 10 −2 S cm −1. A preliminary short-term test (200 min) showed good stability during chrono-amperometry measurements.