Researchers Engineered New Alkaline Redox Flow Battery
The design uses ligand engineering to achieve stable iron-chromium energy storage with low material costs.
Updated on Sept. 30, 2026 in Energy
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Researchers have developed an alkaline iron-chromium redox flow battery that utilizes ligand engineering to suppress hydrogen evolution. The experimental system, currently in the research stage, demonstrated high efficiency over 500 charge-discharge cycles.
Why it matters
This approach addresses the historically sluggish kinetics and parasitic side reactions that have limited the viability of iron-chromium flow batteries. By tuning redox potentials at the molecular level, this method could enable lower-cost, long-duration energy storage.
The battery achieves 99.0% coulombic efficiency and 75.8% energy efficiency at 100 mA cm operating at 1.15 V. Its projected raw-material cost is $17.02 kWh with a theoretical capacity of 68.07 Ah L.
The details
The system utilizes a ligand—a molecule that binds to a central metal atom—known as 2,2-Bis(hydroxymethyl)-2,2',2"-nitrilotriethanol to stabilize an octahedral hexacoordinate chromium chelate. This configuration reshapes the electronic structure of the iron and chromium centers, effectively tuning their redox potentials to mitigate parasitic hydrogen evolution. The chromium(III/IV) couple operates at +0.34 V versus the standard hydrogen electrode, facilitating rapid reaction kinetics.
Timeline
September 30, 2026: The research results were published.
The Tech Race
This development represents a significant advancement in the competitive effort to improve iron-chromium redox flow battery performance. It builds upon existing attempts to overcome the sluggish kinetics of chromium couples that have previously hindered their adoption relative to vanadium-based systems.
This technology is currently in the research phase and is not yet available for commercial or industrial deployment. Future scaling will determine if these efficiency gains can be maintained in large-scale energy storage installations.
The takeaway
This development suggests that ligand engineering can significantly lower the barrier for cost-effective, high-efficiency grid storage. Observers should track subsequent peer-reviewed findings regarding the scalability of this specific chelate system in larger flow cell prototypes.
Further reading
For broader context on current storage innovations, visit Energy.
Source note: This article includes information reported by Nature.
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