Long lifespan, recyclability: Can Fe/V flow battery drive transition?

With the cost and efficiency gap with lithium-ion batteries narrowing, the Fe/V flow battery offers a robust, eco-friendly solution to power the world’s sustainable future

- ABDULAZIZ KHATTAK

In May 2025, Saudi Aramco achieved a global milestone by commissioning the world’s first megawatt-scale Iron-Vanadium (Fe/V) flow battery in Wa'ad Al-Shamal, powering gas production with solar energy backup.

This pioneering deployment underscores the growing significance of Fe/V flow batteries in sustainable energy storage.

As the world transitions to a low-carbon future, this electrochemical technology offers a compelling alternative to traditional batteries, blending cost-effectiveness, safety, and scalability.

UNDERSTANDING REDOX FLOW BATTERIES & THE FE/V VARIANT

Redox flow batteries (RFBs) are rechargeable energy storage systems that store energy in liquid electrolytes, which flow through electrochemical cells to generate electricity.

Unlike conventional batteries, RFBs separate energy storage (in electrolyte tanks) from power generation (in cell stacks), allowing independent scaling of capacity and output.

This flexibility makes them ideal for large-scale applications like grid storage and renewable energy integration.

The Iron-Vanadium (Fe/V) flow battery is a hybrid RFB that uses iron and vanadium ions as active materials in its electrolytes.

The positive electrolyte (catholyte) typically contains iron ions (Fe2+/Fe3+), while the negative electrolyte (anolyte) employs vanadium ions (V2+/V3+), separated by an ion-exchange membrane.

The Fe/V flow battery operates through redox reactions, where electrons are transferred between the iron and vanadium ions.

During charging, the iron ions in the catholyte are oxidised from Fe2+ to Fe3+, releasing electrons, while vanadium ions in the anolyte are reduced from V3+ to V2+, accepting electrons.

Discharging reverses this process, generating an electric current as the ions return to their original states.

The membrane allows ion exchange to maintain charge balance without mixing the electrolytes.