Electrochemical impedance spectroscopy study of Ce(IV) with aminopolycarboxylate ligands for redox flow batteries applications

The electrochemical behaviour of cerium with ethylenediamine tetraacetic acid (Ce(IV)–EDTA), ethylenediamine disuccinate (Ce(IV)–EDDS), nitrilotriacetic acid (Ce(IV)–NTA) and diethylenetriamine pentaacetic acid (Ce(IV)–DTPA on a platinum electrode were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) for redox flow batteries (RFB) application. The EIS results confirm the results from CV and were in good agreement with obtained data. Ce(IV)–DTPA results show the least resistance and faster electron transfer compared to Ce(IV)–EDTA, Ce(IV)–EDDS, Ce(IV)–NTA. The diffusion coefficient of 1.1 × 10−6 cm2 s−1, rate constant of 1.6 × 10−4 cm s−1, electrolyte resistance of 1.2 Ω were obtained. A single cell charge/discharge performance of Ce(IV)–DTPA shows as promise for possible application in RFB systems, because of the higher energy and voltage achieved. Therefore, Ce(IV)–DTPA will be a suitable RFB electrolyte compared to Ce(IV), Ce(IV)–EDTA, Ce(IV)–EDDS and Ce(IV)–NTA due to most favoured reversibility and electrochemical properties.

► Electrochemical behaviour of cerium in the presence of DTPA, EDTA, EDDS, NTA ligands were investigated by using CV and EIS for RFB application.
► The performance of the RFB system was evaluated with constant current charge/discharge analysis.
► We found that Ce(IV)–DTPA complex show as a promise electrolyte when compared to other complexes used in this study.