Researchers at Chinese Institute of Metal Research have developed a 6,000-cycle, all-iron flow battery that uses alkaline chemistry. The key is a novel ‘iron-complex negative electrolyte’, that allows 6,000 discharge-recharge cycles without capacity loss.
Could this be the break though to low-cost, long-duration grid-scale energy storage, for which we have been waiting? The world is accelerating rapidly towards the renewable energy era, while it waits for safe, affordable, practical energy storage.
A Practical, Affordable All-Iron Flow Battery
All-iron flow batteries attract interest as ideal candidates for this exciting new role. This is because they are intrinsically safe, and able to simultaneously deliver high power and high capacity.
But the catch has been inefficient transfer of ions through electrolytes between electrodes, and decomposition of critical materials. This has in turn reduced these batteries’ practical value on account of their short cycle life.
The path to the Institute’s 6,000-cycle all-iron flow battery, lay through developing an ultra-stable iron complex negative electrolyte. The team’s report that we link to below, details how they synthesized 11 iron complexes bonded to 12 different organic molecules surrounding them.
The Solution Behind Their 6,000 Cycle Flow Battery
The Chinese Institute of Metal Research subjected these 11 options to multiple theoretical calculations, and numerous trials. They decided to use a novel, iron-based organic molecular complex, with the chemical formula [Fe(HPF)BHS]⁴.
This new compound avoided active material decomposition, while efficiently managing the flow of ions. Proven, measurable benefits include:
- The battery operated for over 6,000 cycles with no capacity decay, and an average coulombic efficiency of 99.4%.
- The energy efficiency remained at 5% at high current density, with impressive peak power density too.
This novel 6,000-cycle all-iron flow battery solution has established a new model for iron-based electrolytes. The improved and cost-effective cycle life, offers a promising solution for large-scale utility energy storage.
More Information
Earth-Abundant Iron-Based Flow Batteries
Spatiotemporal Thermal Energy Storage
Preview Image: Novel Flow Battery Performance
