Iron salt

Unrivaled low costs, high availability of the iron-based storage medium and high temperature resistance make iron-salt technology the storage technology of the future.

World’s most cost-efficient battery technology

Thanks to the unrivaled low cost and unlimited material availability of the iron-based storage medium, iron salt technology has great potential to shape the future of battery storage beyond lithium. For 100% renewable energy around the clock and for a fairer and cleaner world for future generations.

How does it work?

The heart of an iron salt energy storage system is the redox flow battery unit. It is based on two battery half-cells through which liquid electrolyte is pumped in independent cycles. The half-cells are separated by a membrane and together form the full battery cell. The electrolyte is enriched with iron chloride. During charging or discharging, ions and electrons are transferred between the two half-cells, storing, or releasing energy in the electrolyte. In the uncharged state, both cells have identical oxidation levels; charging leads to reducing the electrolyte in one half-cell and oxidizing electrolyte in the other. Within the negative half-cell, the iron in the electrolyte is deposited as metal on the electrode. The battery capacity is dependent on the iron deposition: an increasing amount of iron deposition leads to a higher capacity. The reaction is fully reversible, and iron is re-dissolved in the electrolyte during discharging.

Advantages of the iron salt technology


In storage systems based on redox flow technology, power can be decoupled from capacity and scaled independently according to demand. In a configuration optimized for long duration storage, this leads to a significant reduction in cost per kWh compared to other storage systems.

Universally applicable

Iron Salt technology is a highly temperature-resistant battery technology that can be used worldwide, even in climatically challenging regions. In addition, the storage system can be connected to existing infrastructures in a space-saving and decentralized manner, which additionally ensures the self-sufficient functionality of the storage solution and increases reliability.


With redox flow technology, we are relying on a proven CO2-saving battery technology. Thanks to the ecological redox flow storage technology, power from renewable energies such as solar and wind plants can be used around the clock in a sustainable way and a contribution can be made against climate change.


With iron-salt battery technology, we are relying on an iron-based storage medium – and thus on one of the most abundant materials in the world. The use of ecological materials allows the storage technology to be scaled according to the given necessities, thus enabling economies of scale to be gained.

100% non flammable

Operational safety plays a key role in energy storage. The iron salt technology offers a decisive advantage in this respect: The iron-based electrolyte consists exclusively of non-flammable components, and is mostly pure water.

Pioneering innovations

VoltStorage continuously strives to challenge the status quo and set new standards in storage technology. With the development of the revolutionary iron salt storage technology, VoltStorage is making an important contribution to the development of groundbreaking solutions for Long Duration Batteries. You can find out more about VoltStorage’s current research and development in the Innovation Lab.