Pre‐treatment Effect on the Sulfonated Poly(ether ether ketone) Membrane Transport Properties and Direct Methanol Fuel Cell Performance

Abstract

In this paper a critical study is presented on how the direct methanol fuel cell (DMFC) membrane properties are affected by a pre‐treatment. Membranes based on sulfonated poly(ether ether ketone) (sPEEK) with sulfonation degree (SD) of 42% were used, plain and modified inorganically with 1 wt.% of zirconium oxide. Nafion^® 1135 was used as reference. The results obtained show that the sPEEK polymer (SD=42%) enables the preparation of proton exchange membranes with improved properties compared to Nafion^® and to the ZrO₂‐modified sPEEK membrane, mainly due to its improved relation between proton conductivity and methanol permeation. After the pre‐treatment, the plain sPEEK membrane had a performance 6.4 times higher in terms of maximum power output when used in the DMFC.

Keywords:

• Sulfonated poly(ether ether ketone) (sPEEK)
• nafion
• conductivity
• pervaporation
• permeability coefficients and direct methanol fuel cell

Acknowledgements

The work of Vasco Silva, Valter Silva and Hugo Silva was supported by FCT (Grants SFRH/BD/6818/2001, SFRH/BD/18159/2004 and SFRH/3029/2000, respectively). Vasco Silva would like to acknowledge both FCT and GKSS for the grant assigned to him for his stay at GKSS Forschungszentrum GmbH. The present work was partially supported by FCT projects POCTI/EQU/38075/2001 and POCTI/EQU/45225/2002.