At the beginning of 2020, over half the electricity consumed in Germany was derived from renewable sources. But as the share of renewables grows, the country’s energy storage capacity must be increased proportionately, which means finding better and more sustainable alternatives to the lithium-ion battery.

Redox flow batteries are considered to have great potential, but experts have only recently figured out how to harness the technology in a way that is safe and inexpensive. “In this type of battery, the energy-storing components are dissolved in a solvent and can therefore be stored at a decentralised location, which allows the battery to be scaled as required, from a few millilitres to several cubic metres of electrolyte solution,” explains Prof. Ulrich S. Schubert from the Centre for Energy and Environmental Chemistry Jena (CEEC Jena), in a press release.

The Jena chemists have discovered a promising new polymer electrolyte, which overcomes the two biggest limitations of the technology up to this point, and have published their findings in Advanced Energy Materials. Previously, toxic heavy metal salts such as vanadium dissolved in sulfuric acid would have been used to create the electrolyte material. Furthermore, as the batteries could only work within a maximum temperature of 40 degrees Celsius, an expensive cooling system had to be employed.
The new type of polymer is water-soluble and stores the electricity in iron molecules which means the electrolyte can function at higher temperatures of up to 60 degrees Celsius, eliminating the need for cooling. The new electrolyte is also a more efficient storage medium.

The benefits are manifold: it means electricity can now be stored cheaply in an environmentally-friendly way in a non-toxic, water-based solution. Redox flow batteries are particularly suitable for use in warmer regions such as Africa, India or Brazil.