PVA-SSA-HPA Mixed-Matrix-Membrane Electrolytes for DMFCs

Bhat, SD and Sahu, AK and Jalajakshi, A and Pitchumani, S and Sridhar, P and George, C and Banerjee, A and Chandrakumar, N and Shukla, AK (2010) PVA-SSA-HPA Mixed-Matrix-Membrane Electrolytes for DMFCs. In: Journal of the Electrochemical Society, 157 (10). B1403-B1412.

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Abstract

Stabilized forms of heteropolyacids (HPAs), namely phosphomolybdic acid (PMA), phosphotungstic acid (PTA), and silicotungstic acid (STA), are incorporated into poly (vinyl alcohol) (PVA) cross-linked with sulfosuccinic acid (SSA) to form mixed-matrix membranes for application in direct methanol fuel cells (DMFCs). Bridging SSA between PVA molecules not only strengthens the network but also facilitates proton conduction in HPAs. The mixed-matrix membranes are characterized for their mechanical stability, sorption capability, ion-exchange capacity, and wetting in conjunction with their proton conductivity, methanol permeability, and DMFC performance. Methanol-release kinetics is studied ex situ by volume-localized NMR spectroscopy (employing point-resolved spectroscopy'') with the results clearly demonstrating that the incorporation of certain inorganic fillers in PVA-SSA viz., STA and PTA, retards the methanol-release kinetics under osmotic drag compared to Nafion, although PVA-SSA itself exhibits a still lower methanol permeability. The methanol crossover rate for PVA-SSA-HPA-bridged-mixed-matrix membranes decreases dramatically with increasing current density rendering higher DMFC performance in relation to a DMFC using a pristine PVA-SSA membrane. A peak power density of 150 mW/cm(2) at a load current density of 500 mA/cm(2) is achieved for the DMFC using a PVA-SSA-STA-bridged-mixed-matrix-membrane electrolyte. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3465653] All rights reserved.

Item Type:	Journal Article
Publication:	Journal of the Electrochemical Society
Publisher:	The Electrochemical Society
Additional Information:	Copyright of this article belongs to The Electrochemical Society.
Keywords:	Current density, direct methanol fuel cells, electrolytes, ion exchange, mechanical stability, membranes, nuclear magnetic resonance, permeability, polymers, sorption, wetting .
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	15 Sep 2010 11:41
Last Modified:	19 Sep 2010 06:16
URI:	http://eprints.iisc.ac.in/id/eprint/32127

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