'Nearly 80 times cheaper than lithium': China unveils low-cost 'all-iron flow battery' for renewable energy storage
Scientists from the Institute of Metal Research under the Chinese Academy of Sciences (CAS) developed a highly stable iron-based electrolyte capable of enduring more than 6,000 charge-discharge cycles with virtually no capacity loss – a record in the field.
China has unveiled a breakthrough in low-cost "all-iron flow battery" technology that could dramatically cut renewable energy storage costs while offering far longer operational life than current alternatives, reports South China Morning Post.
Scientists from the Institute of Metal Research under the Chinese Academy of Sciences (CAS) developed a highly stable iron-based electrolyte capable of enduring more than 6,000 charge-discharge cycles with virtually no capacity loss – a record in the field, according to findings published in Advanced Energy Materials.
CAS described the innovation as a "low-cost, long-life solution for large-scale energy storage" that could help address one of the biggest obstacles in the global transition to renewable power: efficiently storing intermittent energy from solar and wind sources to stabilise electricity grids.
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Iron, the researchers noted, is more than 80 times cheaper than lithium as an industrial raw material, making it a far more affordable option for large-scale battery deployment if commercial scaling proves successful.
To overcome previous limitations, the team redesigned the molecular structure of the battery's negative electrolyte, creating 11 iron complexes from 12 organic ligands before identifying [Fe(HPF)BHS]⁴⁻ as the most stable.
The compound's bulky molecular design protects the iron center, while its negatively charged groups reduce unwanted chemical reactions and minimise material crossover within the battery system.
Performance tests showed the battery operating at 80 mA·cm⁻² for over 6,000 cycles without measurable degradation, achieving an average coulombic efficiency of 99.4%.
At higher current levels, the system reached a peak power density of 392.1 mW·cm⁻² while maintaining 78.5% energy efficiency, demonstrating resilience under heavier power demand.
Researchers estimate the battery's lifespan could exceed 16 years of daily use without significant performance decline.
Beyond cost advantages, iron's abundance on Earth also offers greater supply security than lithium, while the battery's water-based electrolyte eliminates the fire risks associated with flammable lithium-ion systems.
Although the development marks a major advance in renewable energy storage, scientists caution that large-scale commercial deployment will depend on successful real-world testing beyond laboratory conditions.
