The battery of the future: energy storage produced at low cost and more sustainably

The biggest problem with renewable energies is still that the electricity generated cannot be stored and is therefore not available at all times. For this reason, the Friedrich Schiller University in Jena has been working on the battery of the future for some time. Prof. Dr. Ulrich S. Schubert, for example, is focusing his research on so-called redox flow batteries based on polymers, a class of electrochemical energy storage devices that work on the basis of aqueous electrolytes with organic macromolecules (plastics).

In the interview with COMPAMED-tradefair.com, the chemist and materials scientist talks about why he relies on polymers and what goals he is pursuing in his new project "FutureBAT", which is funded with an "ERC Advanced Grant". 

Prof. Dr. Schubert, you rely on polymer-based redox flow batteries in your research - why? What are the advantages of this type and what difficulties are there at present?

Dr. Ulrich S. Schubert: Polymer-based redox flow batteries are a fairly new invention. We presented this type of battery for the first time at the end of 2015 in a publication in the leading journal Nature. So far, this type of battery is still limited by the relatively high viscosity of the liquids (this reduces the achievable energy densities) and the limited temperature stabilities. However, the advantages are the low-cost membrane systems, the avoidance of acids or bases in electrolytes, and the scalability and principal production possibilities of organic polymers.

What role do polymers play in this?

Schubert: Redox-active polymers or redox-active organic molecules are a way of replacing critical, toxic or expensive metals as active materials in redox flow batteries. This also enables a significant reduction in the CO2 footprint of batteries. Polymers can also be produced from renewable raw materials or Power-2-X technologies (i.e., also using renewable energies). Furthermore, polymer-based redox flow batteries can also use inexpensive size-exclusion membranes, which significantly reduces the cost of electrochemical cells. Furthermore, battery systems can be constructed that do not require acid, i.e., use salt water with neutral pH.

What goals do you want to achieve in the "FutureBAT" project?

Dr. Schubert: Within the framework of the ERC Advanced Grant project, we want to develop the next generations of polymer-based redox flow batteries. To this end, we not only want to expand the chemical redox-active molecules, but also introduce new polymer carriers, vary the polymer architectures, establish new sensor systems and research radically new operating concepts. This should, for example, increase energy densities and extend the temperature window. This would allow such batteries to be operated without cooling in summer under solar radiation, for example, or to be used in underground caverns.

In the best case scenario, you succeed in doing all that. What then will make up the battery of the future and where could its areas of application lie?

Dr. Schubert: On the one hand, applications in hospitals and in decentralized medical facilities would be feasible. Use in neighborhood solutions for storing electrical energy in city districts or villages as well as large residential complexes is also very conceivable. On the other hand, the areas of application for polymer-based redox flow batteries range from use in solar and wind farms, on ferries and to supply container ships in the port, to pumpable liquid fuel in municipal waste vehicles.