New Insights into Properties of Methanol Transport in Sulfonated Polysulfone Composite Membranes for Direct Methanol Fuel Cells.

Cataldo Simari,Francesco Lufrano,Isabella Nicotera,Vincenzo Baglio,Antonino Salvatore Aricò

doi:10.3390/polym13091386

Cataldo Simari, Francesco Lufrano + Show 3 more

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https://doi.org/10.3390/polym13091386

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Abstract

Methanol crossover through a polymer electrolyte membrane has numerous negative effects on direct methanol fuel cells (DMFCs) because it decreases the cell voltage due to a mixed potential (occurrence of both oxygen reduction and methanol oxidation reactions) at the cathode, lowers the overall fuel utilization and contributes to long-term membrane degradation. In this work, an investigation of methanol transport properties of composite membranes based on sulfonated polysulfone (sPSf) and modified silica filler is carried out using the PFG-NMR technique, mainly focusing on high methanol concentration (i.e., 5 M). The influence of methanol crossover on the performance of DMFCs equipped with low-cost sPSf-based membranes operating with 5 M methanol solution at the anode is studied, with particular emphasis on the composite membrane approach. Using a surface-modified-silica filler into composite membranes based on sPSf allows reducing methanol cross-over of 50% compared with the pristine membrane, making it a good candidate to be used as polymer electrolyte for high energy DMFCs.

Highlights

direct methanol fuel cells (DMFCs) utilize a polymer electrolyte membrane (PEM) as the electrolyte and separator between anode and cathode; the proton conductivity and methanol permeability of this latter are among the key factors limiting the DMFC performance, whereas the membrane cost and durability greatly influence the potential commercialization of complete devices [6,7,8]
The approach did not involve the use of thicker membranes, as conventionally used to decrease methanol crossover, but a proper tailoring of the characteristics of fillers used for the fabrication of composite membranes
A low cost sulfonated polysulfone was employed to reduce the cost of polymer electrolyte membranes and increase the efficiency of DMFC

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Direct methanol fuel cells (DMFCs) are envisaged as powerful systems for generation electronic devices, capable to sustain longer operation compared to Li-batteries without the drawbacks of the time-consuming charging process [1,2,3,4,5]. DMFCs utilize a polymer electrolyte membrane (PEM) as the electrolyte and separator between anode and cathode; the proton conductivity and methanol permeability of this latter are among the key factors limiting the DMFC performance, whereas the membrane cost and durability greatly influence the potential commercialization of complete devices [6,7,8]. State-of-the-art membranes for DMFCs are based on perfluorosulfonic acid membranes (PFSAs), such as

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