Thermochemical Stability Study of Alkyl-Tethered Quaternary Ammonium Cations for Anion Exchange Membrane Fuel Cells

Hai Long, Bryan Pivovar, Matthew Sturgeon, Angela Mohanty, Steven Tignor, Chulsung Bae

Research output: Contribution to journalArticlepeer-review

42 Scopus Citations

Abstract

The increased interest in the use of anion exchange membranes (AEMs) for applications in electrochemical devices has prompted significant efforts in designing materials with robust stability in alkaline media. Most reported AEMs suffer from polymer backbone degradation as well as cation functional group degradation. In this report, we provide comprehensive experimental investigations for the analysis of cation functional group stability under alkaline media. A silver oxide-mediated ion exchange method and an accelerated stability test in aqueous KOH solutions at elevated temperatures using a Parr reactor were used to evaluate a broad scope of quaternary ammonium (QA) cationic model compound structures, particularly focusing on alkyl-tethered cations. Additionally, byproduct analysis was employed to gain better understanding of degradation pathways and trends of alkaline stability. Experimental results under different conditions gave consistent trends in the order of cation stability of various QA small molecule model compounds. Overall, cations that are benzyl-substituted or that are near to electronegative atoms (such as oxygen) degrade faster in alkaline media in comparison to alkyl-tethered QAs. These comprehensive model compound stability studies provide valuable information regarding the relative stability of various cation structures and can help guide researchers towards designing new and promising candidates for AEM materials.

Original languageAmerican English
Pages (from-to)F1279-F1285
JournalJournal of the Electrochemical Society
Volume164
Issue number13
DOIs
StatePublished - 2017

Bibliographical note

Publisher Copyright:
© 2017 The Electrochemical Society. All rights reserved.

NREL Publication Number

  • NREL/JA-2C00-67596

Keywords

  • alkaline membrane fuel cells
  • solid electrolyte
  • stability

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