Spanish scientists confirm 10,000-cycle lifespan for iron-lead flow battery

Spanish research center CIC energiGUNE has successfully completed testing of an iron-lead redox flow battery, achieving as many as 10,000 charge-discharge cycles. The new technology uses inexpensive, widely available raw materials and has been designed for multi-hour energy storage in stationary power systems.

Simplified design and fluorine-free membrane

Tested at temperatures ranging from 25°C to 30°C, the battery features an innovative architecture. Unlike conventional flow batteries, which require two separate circulation loops, the Spanish design relies on a single electrolyte loop. Reducing the number of components significantly lowers the cost of the overall system.

In addition, the device uses a membrane free of fluorine compounds. This solution reduces internal resistance and limits unwanted crossover of chemical species between the two sides of the cell. An important advantage of the active materials used—iron and lead—is their widespread availability, as well as the well-established supply chains and recycling infrastructure already in place.

Scalability and next stages of development

Flow batteries store energy in liquid electrolytes kept in external tanks. This allows power and energy capacity to be scaled independently. Increasing storage capacity requires only larger tanks, while power depends on the size and number of cells. This characteristic makes the technology particularly well suited to balancing wind and solar farms, operation in microgrids, and industrial energy management.

Following successful laboratory trials on small cells and larger battery stacks, researchers at CIC energiGUNE are moving on to the next stage. This involves developing kilowatt-scale modules using computer simulations, system design, and further experimental testing.