- Iron Flow battery operates 6,000 cycles without measurable loss of capacity
- New electrolyte chemistry reduces membrane degradation and crossover issues
- Iron materials offer a low-cost alternative for large-scale renewable energy storage
Chinese researchers say they have made new advances in iron-based flow batteries, which could reduce the cost of storing renewable energy while extending useful life.
According to the results published in Advanced Energy Materials.
Iron flow batteries have been studied for years but face stability problems that limit their long-term use. The active materials inside the battery tend to degrade or leak through the membranes, reducing efficiency and lifespan.
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Iron is 80 times cheaper than lithium
The researchers addressed these limitations by rethinking the molecular structure of the negative electrolyte used inside the system.
The team synthesized 11 iron complexes constructed from 12 organic ligands before identifying a compound known as [Fe(HPF)BHS]⁴⁻ as the most stable candidate.
Its bulky structure creates physical protection around the center of the iron, while negatively charged groups help prevent unwanted reactions and reduce the crossing of materials across the membrane.
Testing showed the battery operated at 80 mA cm⁻² for more than 6,000 cycles without loss of capacity and with an average coulombic efficiency of 99.4%, based on performance data published by the research team.
Under higher current conditions, the system achieved a maximum power density of 392.1 mW·cm⁻² while maintaining a power efficiency of 78.5%, indicating stable performance under higher power demand.
The researchers linked the number of cycles to long-term use, estimating that performance is equivalent to more than 16 years of daily use without measurable degradation.
Iron is a raw material more than 80 times cheaper than lithium, which could make large-scale energy storage much less expensive, provided the technology scales successfully.
Iron is also widely available, ranking among the most abundant metals on Earth, reducing concerns about supply shortages compared to lithium.
All-iron flow batteries use water-based electrolytes instead of the flammable liquids found in lithium-ion systems. This chemistry removes the conditions necessary for thermal runaway, which is the chain reaction that can lead to fires or battery explosions.
Large-scale energy storage remains one of the major technical challenges in renewable energy development, since electricity production from solar and wind fluctuates depending on weather conditions.
The research improves the stability of iron-based electrolytes, but long-term testing outside of controlled environments will determine how the chemistry performs in real grid installations.
Via SCMP
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