Kinetics of the Charge/Discharge Characteristics of Redox Flow Battery Electrolytes

Abstract

A comparison of the electrochemical behavior of Ce(IV) and its complexes of ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminedisuccinic acid (EDDS), and nitrilotriacetic acid (NTA) using cyclic voltammetry (CV) and rotating disc electrode (RDE) on Pt-electrode were carried out. All complexes had an anodic cathodic ratio greater than 1. The Ce(IV)-DTPA had the best properties: highest peak potential, better reversibility, and higher peak current. Potential usage of the Ce(IV)-DTPA in redox flow batteries (RFB) was confirmed by the electrochemical impedance spectroscopy results: lowest electrolyte and charge transfer resistance. The performance evaluation of RFB employing Ce(IV) and Ce(IV) complexes of DTPA and EDTA with constant current charge/discharge analysis proved that CE(IV)-DTPA complex has a potential as an anode in RFB. A maximum potential of 1 V and a minimum voltage of 2 V were achieved. Highest energy, voltage, and coulombic efficiencies of 85%, 93%, and 92% were obtained, respectively.

Keywords:

• Ce(IV)-DTPA
• Cerium
• Charge/discharge
• Complexes
• Electrochemical impedance spectroscopy
• Redox flow battery

Acknowledgments

This paper is part of a Special Issue of Analytical Letters focusing on papers presented at the 10th International Symposium on Kinetics in Analytical Chemistry (KAC-10).

Notes

^a Current density of 40 mA/cm².