Researchers at the Institute of Metal Research under the Chinese Academy of Sciences have demonstrated an alkaline all-iron flow battery that completed more than 6,000 charge-discharge cycles with no measurable capacity loss, a result published in the 2026 edition of Advanced Energy Materials.
The cell uses a redesigned electrolyte and targets grid-scale stationary storage. Iron, the active material, costs roughly 80 times less than lithium on a raw-material basis, according to the research team.
Flow batteries separate energy capacity from power rating by storing charge in liquid electrolytes held in external tanks. That architecture makes them candidates for multi-hour and long-duration storage, where lithium-ion systems face cost and degradation constraints. The iron chemistry tested in Beijing replaces the vanadium or organic redox couples used in earlier flow designs with an abundant, low-cost metal.
Cycle life is the headline metric. Six thousand daily cycles correspond to roughly 16 years of operation without capacity fade, far exceeding the warranty periods of most lithium-ion grid assets. The paper does not disclose round-trip efficiency, power density, or system-level cost estimates, and the work remains at the laboratory stage.
Commercial deployment would require scaling the electrolyte formulation, proving stack durability under real-world thermal cycling, and building a supply chain for iron-based flow hardware — none of which are addressed in the current publication. Competing long-duration technologies, including vanadium flow, sodium-ion, and compressed-air storage, are already in pilot or early commercial operation.