One-Step Cationic Grafting of 4-Hydroxy-TEMPO and its Application in a Hybrid Redox Flow Battery with a Crosslinked PBI Membrane
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Updated: Feb 26, 2026
A Protocol for Electrochemical Evaluations and State of Charge Diagnostics of a Symmetric Organic Redox Flow Battery
Published on: February 13, 2017
Zhenjun Chang1,2,3, Dirk Henkensmeier4,5, Ruiyong Chen1,2
1Transfercenter Sustainable Electrochemistry, Saarland University, 66125, Saarbrücken, Germany.
Abstract:
By using a one-step epoxide ring-opening reaction between 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (4-hydroxy-TEMPO) and glycidyltrimethylammonium cation (GTMA+ ), we synthesized a cation-grafted TEMPO (g+ -TEMPO) and studied its electrochemical performance against a Zn2+ /Zn anode in a hybrid redox flow battery. To conduct Cl- counter anions, a crosslinked methylated polybenzimidazole (PBI) membrane was prepared and placed between the catholyte and anolyte. Compared to 4-hydroxy-TEMPO, the positively charged g+ - TEMPO exhibits enhanced reaction kinetics. Moreover, flow battery tests with g+ -TEMPO show improved Coulombic, voltage, and energy efficiencies and cycling stability over 140 cycles. Crossover of active species through the membrane was not detected.
