A symmetric organic-based nonaqueous redox flow battery and its state of charge diagnostics by FTIR

Wentao Duan, Rama S. Vemuri, Jarrod D. Milshtein, Sydney Laramie, Rylan D. Dmello, Jinhua Huang, Lu Zhang, Dehong Hu, M. Vijayakumar, Wei Wang, Jun Liu, Robert M. Darling, Levi Thompson, Kyle Smith, Jeffery S. Moore, Fikile R. Brushett, Xiaoliang Wei

Research output: Contribution to journalArticlepeer-review


Redox flow batteries have shown outstanding promise for grid-scale energy storage to promote utilization of renewable energy and improve grid stability. Nonaqueous battery systems can potentially achieve high energy density because of their broad voltage window. In this paper, we report a new organic redox-active material for use in a nonaqueous redox flow battery, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) that has high solubility (>2.6 M) in organic solvents. PTIO exhibits electrochemically reversible disproportionation reactions and thus can serve as both anolyte and catholyte redox materials in a symmetric flow cell. The PTIO flow battery has a moderate cell voltage of ∼1.7 V and shows good cyclability under both cyclic voltammetry and flow cell conditions. Moreover, we demonstrate that FTIR can offer accurate estimation of the PTIO concentration in electrolytes and determine the state of charge of the PTIO flow cell, suggesting FTIR as a powerful online battery status sensor. This study is expected to inspire more insights in this under-addressed area of state of charge analysis aiming at operational safety and reliability of flow batteries.

Original languageEnglish (US)
Pages (from-to)5448-5456
Number of pages9
JournalJournal of Materials Chemistry A
Issue number15
StatePublished - Apr 21 2016

ASJC Scopus subject areas

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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