Related Experiment Video
Updated: Sep 17, 2025
A Protocol for Electrochemical Evaluations and State of Charge Diagnostics of a Symmetric Organic Redox Flow Battery
Published on: February 13, 2017
Elucidating Ligand Exchange Dynamics of Hexacyanochromate-Based Redox Mediators in Aqueous Iron-Chromium Redox Flow
Ji-Eun Jang1, Vithiya Muralidharan1, Yoon Seong Kim2
1School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919, Republic of Korea.
Abstract:
Aqueous redox flow batteries (AQRFBs) are revolutionizing energy storage by integrating sustainability with cutting-edge innovation. Among them, Iron-Chromium RFBs (Fe-Cr RFBs), which utilize aqueous-based electrolytes, effectively address critical challenges in renewable energy integration while offering unparalleled safety, low-cost scalability and environmental compatibility. Potassium hexacyanochromate (K3[Cr(CN)6]) has emerged as a promising negolyte material in Fe-Cr RFBs due to its favorable electrochemical properties. However, enhancing its long-term stability and elucidating its structural transformations remain crucial for optimized performance. Investigations into ligand exchange mechanism reveal connections to detrimental side reactions, notably hydrogen evolution reaction (HER) and hexacyanochromate instability, highlighting pathways for targeted improvement. Density functional theory (DFT) calculations illuminate the effects of ligand exchange dynamics and structural variations on redox stability, providing mechanistic insights into electrolyte behavior. By strategically incorporating sodium hydroxide with sodium cyanide as supporting electrolytes, our study demonstrates significantly improved stability of the redox couple, achieving a stable cycling performance over 250 cycles with an energy density of 13.91 Wh L-1 and energy efficiencies exceeding 76%-77%. This research provides valuable insights into the degradation pathways of hexacyanochromate-based negolyte and emphasizes the importance of optimized electrolyte design for advancing sustainable energy storage technologies.
More Related Videos
06:53Author Spotlight: Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
Published on: June 9, 2023
07:55Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering
Published on: April 17, 2018
Related Concept Videos
01:30Ladder Diagrams: Redox Equilibria
Consider the Fe3+/Fe2+ half-reaction, which has a standard-state potential of +0.771 V. At potentials more positive than +0.771 V, Fe3+ predominates, whereas Fe2+...
03:45Formation of Complex Ions
01:23Redox Equilibria: Overview
03:02Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
02:51Metal-Ligand Bonds
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
02:59The Nernst Equation
The interconnection between standard cell potentials and various thermodynamic parameters such as the standard free energy change ΔG° and equilibrium constant K has been previously explored. For example, a redox reaction involving zinc(II) and tin(II) ions at 1 M concentration with Eºcell = +0.291 V and ΔG° = −56.2 kJ is spontaneous.