Journal of The Electrochemical Society, 158 (11) B1319-B1328 (2011) B1319 0013-4651/2011/158(11)/B1319/10/$28.00 © The Electrochemical Society Bio-Composite Membrane Electrolytes for Direct Methanol Fuel Cells

A new class of bio-composite polymer electrolyte membranes comprising chitosan (CS) and certain biomolecules in particular, plant hormones such as 3-indole acetic acid (IAA), 4-chlorophenoxy acetic acid (CAA) and 1-naphthalene acetic acid (NAA) are explored to realize proton-conducting bio-composite membranes for application in direct methanol fuel cells (DMFCs). The sorption capability, proton conductivity and ion-exchange capacity of the membranes are characterized in conjunction with their thermal and mechanical behaviour. A novel approach to measure the permeability of the membranes to both water and methanol is also reported, employing NMR imaging and volume localized NMR spectroscopy, using a two compartment permeability cell. A DMFC using CS-IAA composite membrane, operating with 2M aqueous methanol and air at 70◦C delivers a peak power density of 25 mW/cm2 at a load current density of 150 mA/cm2. The study opens up the use of bio-compatible membranes in polymer-electrolyte-membrane fuel cells. © 2011 The Electrochemical Society. [DOI: 10.1149/2.030111jes] All rights reserved. Manuscript submitted February 24, 2011; revised manuscript received August 5, 2011. Published October 5, 2011. Direct Methanol Fuel Cells (DMFCs) are promising candidate for automotive and portable power applications owing to their simplified system design, and high energy density of methanol, in addition to their easy handling.1–3 During the last decade, the global market fo