Currently, the most advanced electrochemical energy storage systems are based on vanadium salts as the electrolyte. However, vanadium is an expensive and scarce material. A team from the CSIC has developed a new electrolyte based on iron salts, incorporating the necessary additives to enable the battery to function efficiently and at a high voltage.

Wind turbine. Image: José Alba.

The widespread adoption of renewable energy sources requires energy storage systems capable of storing energy generated during peak sunlight and wind periods, for instance.

For this reason, electrochemical energy storage devices are considered essential. These include lithium-ion batteries, electrolysers, primary and secondary batteries, fuel cells, supercapacitors, and other devices.

The most advanced electrolytes in this technology are based on vanadium salts. However, their scarcity and high cost limit broader adoption, making it necessary to explore less expensive and more abundant materials.

A team from CSIC has developed a new electrolyte based on iron salts, including the necessary additives for the battery to function effectively, stably, and at a high voltage.

The additives used in this electrolyte address the primary issues of these batteries, such as the irreversible generation of hydrogen at the negative electrode and the precipitation of iron salts at the positive electrode. These various additives include substances capable of regulating the pH and ionic conductivity of the solution, as well as other substances that maintain a reducing environment. This inhibits the oxidation of iron (II) to iron (III) and the evolution of hydrogen, without interfering with or hindering the essential battery reactions, such as the oxidation and reduction reactions of the iron species present in the medium.

Among the advantages of this technology, it is noted that the additives promote interaction with the electrode surface, enhance membrane performance, and maintain electrolyte stability under operating conditions. The only active species involved in the battery’s charge and discharge are iron cations, which can be prepared at various concentrations and participate in different redox reactions.

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