Research group “ThüNaBsE”: The Thuringian Forest Battery

The research group “ThüNaBsE: Thuringian sodium-ion battery for scalable energy storage“, funded by the free state of Thuringia and the European Social Fund, is a joint project of the Center for Energy and Environmental Chemistry Jena, a part of Friedrich Schiller University Jena (working groups of Prof. Martin Oschatz and Prof. Benjamin Dietzek-Ivansič) and Fraunhofer IKTS in Hermsdorf and Arnstadt. The aim of the project is to develop and evaluate a sodium-ion battery with a cycle life of 200 discharges and recharges, starting with the synthesis and investigation of active materials and leading to the 1 Ah full cell. When selecting materials, a special focus will be placed on sustainability and locally available resources. For this purpose, the raw material lignin (Fig. 1) will be utilized and components with high fluorine content will be avoided wherever possible. The project is supported by an industrial advisory board of regional companies. These include Mercer Rosenthal GmbH, Glatt Ingenieurstechnik GmbH, IBU-tec AG and EAS Batteries GmbH.  

Negative electrode

Mercer Rosenthal is providing the project consortium with lignin from their lignin center, which opened in 2024. This waste product from the wood industry can be processed further into hard carbons (Fig. 2 and 3) using thermal treatments in inert atmosphere. Such hard carbons are the crucial component of negative electrodes in sodium-ion batteries. Whereas the well-established graphite electrode known from lithium-ion batteries cannot be used in sodium-ion battery analogues, the disordered structure of hard carbons, on the other hand, is well-suited to reversibly store and release sodiumions.

Positive electrode

Prussian Blue analogues will be the material of choice to act as active material in the positive electrode. These have the advantage of containing no critical heavy metal elements or other costly components. Furthermore, they are non-toxic and can be synthesized from elements of broad abundance in Germany.

The experimental efforts will be supported by finite element simulations and spectroscopic investigations (in-operando IR-, Raman- and impedance spectroscopy etc.) to gain a deeper understanding of the material properties during cell operation and to clarify different degradation as well as ageing events. The consortium has set itself the goal of developing a 1 Ah Na-ion battery by 2026  based on the electrodes described. It aims to make an important contribution to greater independence rom critical raw materials and a shift towards cheaper, more sustainable and safer battery storage systems.