Nafion membranes annealed at high temperature and controlled humidity: structure, conductivity, and fuel cell performance

Author(s)

Matos, Bruno R. ^[1] ; Dresch, Mauro A. ^[1] ; Santiago, Elisabete I. ^[1] ; Moraes, Leticia P. R. ^[1] ; Carastan, Danilo J. ^[2] ; Schoenmaker, Jeroen ^[2] ; Velasco-Davalos, Ivan A. ^[3] ; Ruediger, Andreas ^[3] ; Tavares, Ana C. ^[3] ; Fonseca, Fabio C. ^[1]

Affiliation

^[1] IPEN CNEN SP, Inst Pesquisas Energet & Nucl, BR-05508000 Sao Paulo, SP - Brazil

^[2] Univ Fed ABC, BR-09219170 Santo Andre, SP - Brazil

^[3] INRS EMT, Varennes, PQ J3X 1S2 - Canada

• Document type: Journal article
• Source: Electrochimica Acta; v. 196, p. 110-117, APR 1 2016.
• Web of Science Citations: 4

Abstract

The relationship between electrical and morphological properties of annealed Nafion samples is investigated by X-ray diffraction (XRD), small angle X-ray scattering (SAXS), atomic force microscopy (AFM), and impedance spectroscopy. Experimental data reveal that the heat treatment at high temperature (T similar to 130-140 degrees C) with low relative humidity (RH similar to 0%) results in significant changes of Nafion such as increased crystallinity and decreased average distance of hydrophilic domains. Such effects were practically absent when the same heat treatment was carried out at high RH similar to 100%. The effects of annealing with controlled RH were reflected in the polymer electrolyte fuel cell (PEFC) tests in which the measured performance was markedly reduced for Nafion samples annealed at low RH. Such a feature was related to decreased microstructural stability, water sorption and proton conductivity of the annealed membrane. The observed effects are relevant to evaluate degradation of Nafion during both fuel cell assembly and harsh PEFC operating conditions. Moreover, the experimental results contribute to advance the understanding of Nafion's properties at high temperature for the development of high-performance ionomer membranes. (C) 2016 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 13/50151-5 - Development of composite electrolytes containing inorganic particles of high proton conductivity for direct ethanol fuel cells
• Grantee: Bruno Ribeiro de Matos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 14/09087-4 - Studies on the use of bioethanol in proton exchange membrane and solid oxide fuel cells
• Grantee: Marcelo Linardi
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 14/50279-4 - Brasil Research Centre for Gas Innovation
• Grantee: Julio Romano Meneghini
• Support Opportunities: Research Grants - Research Centers in Engineering Program