Investigations of conductivity in FEP-based radiation-grafted alkaline anion-exchange membranes

Slade, RCT and Varcoe, JR (2005) Investigations of conductivity in FEP-based radiation-grafted alkaline anion-exchange membranes Solid State Ionics, 176 (5-6). 585 - 597. ISSN 0167-2738

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Abstract

A series of radiation-grafted alkaline anion-exchange membranes (AAEMs) with degrees of grafting (by mass) in the range 20 – 26% were produced and characterised. Conductivities (from impedance spectroscopy) up to 0.023 ± 0.001 S cm-1 at 50 ± 1°C were demonstrated, which are between 20 – 50% of values for the commercial acid-form membrane Nafion®-115 (conductivity = ± 0.004 (65°C) – 0.104 ± 0.008 (50 ± 1°C) S cm-1, depending on the level of hydration (10 and 23 water molecules per sulfonate group respectively)). This significant result clearly indicates the suitability of these AAEMs for application in fuel cells at temperatures below the widely accepted alkaline membrane thermal stability limit of 60°C. Statistical analysis of the results of ion-exchange capacity and conductivity studies on the AAEMs indicate the presence of heterogeneity in the grafting levels within the AAEMs and suggest that more synthetic optimization work is required. The empirical activation energies (Arrhenius behaviour assumed) for the hydroxide ion migration in the AAEMs (12.6 ± 0.6 kJ mol-1 at the 95% confidence level) is twice the value for proton migration found for fully hydrated Nafion®-115 (6.0 ± 0.8 kJ mol-1) and shows that hydroxide ion mobility is more strongly temperature dependant.

Item Type:	Article
Additional Information:	Copyright © 2004 Elsevier B.V. All rights reserved. NOTICE: this is the author’s version of a work that was accepted for publication in Solid State Ionics. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Solid State Ionics, 176(5-6), February 2005, DOI 10.1016/j.ssi.2004.09.044.
Divisions:	Faculty of Engineering and Physical Sciences > Chemistry
Depositing User:	Mr Adam Field
Date Deposited:	23 Apr 2012 13:41
Last Modified:	23 Sep 2013 19:21
URI:	http://epubs.surrey.ac.uk/id/eprint/375321

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