Electrolytes for Next-Generation Redox Flow Batteries

Redox flow batteries are considered to be one of the promising energy storage technologies for stationary applications. They allow independent scaling of both electrical power and storage capacity and can therefore be used in applications where storage periods of several hours are required.

Vanadium redox flow batteries (VRFBs) represent the state of the art and are commercially available. However, the electrolyte costs as well as the energy density of the vanadium redox flow battery are limiting parameters that cannot be improved significantly in the future.

For the large-scale storage of renewable energy, new storage solutions are required that are efficient, powerful, and cost-effective. Hydrogen/bromine redox flow batteries for example offer higher power and energy densities than today’s vanadium redox flow batteries. An advantage of the zinc/air redox flow battery is its extremely high energy density, which means that a very high storage capacity can be achieved. A redox flow battery based on iron is considered to be particularly environmentally friendly. Furthermore, iron as an active species is inexpensive and available worldwide.