Phosphonate-based iron complex for a cost-effective and long cycling aqueous iron redox flow battery.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38528014.
- Also identified by DOI 10.1038/s41467-024-45862-3 and PMC identifier 10963763.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
A promising metal-organic complex, iron (Fe)-NTMPA<sub>2</sub>, consisting of Fe(III) chloride and nitrilotri-(methylphosphonic acid) (NTMPA), is designed for use in aqueous iron redox flow batteries. A full-cell testing, where a concentrated Fe-NTMPA<sub>2</sub> anolyte (0.67 M) is paired with a Fe-CN catholyte, demonstrates exceptional cycling stability over 1000 charge/discharge cycles, and noteworthy performances, including 96% capacity utilization, a minimal capacity fade rate of 0.0013% per cycle (1.3% over 1,000 cycles), high Coulombic efficiency and energy efficiency near 100% and 87%, respectively, all achieved under a current density of 20 mA·cm<sup>-</sup>². Furthermore, density functional theory unveils two potential coordination structures for Fe-NTMPA<sub>2</sub> complexes, improving the understanding between the ligand coordination environment and electron transfer kinetics. When paired with a high redox potential Fe-Dcbpy/CN catholyte, 2,2'-bipyridine-4,4'-dicarboxylic (Dcbpy) acid and cyanide (CN) ligands, Fe-NTMPA<sub>2</sub> demonstrates a notably elevated cell voltage of 1 V, enabling a practical energy density of up to 9 Wh/L.