“Sodium-Ion and sodium Metal BAtteries for efficient and sustainable next-generation energy storage"

A consortium led by the TU is breaking new ground in sustainable energy storage. The “SIMBA” project aims to develop a safe, low-cost and environmentally friendly all-solid-state-sodium battery for stationary use, which could help solve a major problem of the energy revolution. The EU is supporting SIMBA with eight million euros within the "Horizon 2020” program.

Next generation of energy storage

The SIMBA concept, a H2020 project on sodium-ion and sodium metal batteries.
The SIMBA concept, a H2020 project on sodium-ion and sodium metal batteries.

Project SIMBA (“Sodium-Ion and sodium Metal Batteries for efficient and sustainable next-generation energy storage”) is being carried out by an international consortium and coordinated by Professor Ralf Riedel and Dr. Magdalena Graczyk-Zajac at the Institute of Materials Science at TU Darmstadt. It focuses on a key problem of the use of renewable energies: In principle, they are inexhaustible, but they are not available in equal quantities at all times. Reliable use requires efficient and economical energy storage technologies for grid stabilization. Electrochemical energy storage systems offer the most promising solution.

Among the battery systems available, the sodium-ion technology has the potential to represent the next generation of low cost and environmentally friendly electrochemical energy storage systems, especially for stationary energy storage applications.

The ultimate goal of SIMBA is to develop a safe and low-cost all-solid-state-sodium battery technology for stationary application. Critical raw materials will be replaced to a large extent by sustainable, recyclable battery materials, thus reducing supply risks and environmental impact, which are currently affecting other technologies, i.e. Lithium-ion batteries. The unprecedented concept of SIMBA is based on the integration of a sodium metal anode in a sodium free assembly architecture including a highly porous support on the anode side, a conductive solid electrolyte and an innovative iron-based cathode material.

By designing and modelling interfaces and a profound understanding of sodium storage and transport mechanisms within the all-solid-state system, SIMBA moves away from a conservative approach limited to Lithium-ion based systems.

Professor Ralf Riedel and Dr. Magdalena Graczyk-Zajac from the Department of Materials and Earth Sciences
Professor Ralf Riedel and Dr. Magdalena Graczyk-Zajac from the Department of Materials and Earth Sciences

Within the SIMBA consortium, the interdiscliplinary team of TU Darmstadt will research and develop innovative battery anode materials (responsible: Prof. Ralf Riedel, Department of Materials and Earth Sciences) as well as characterize transport phenomena accross the materials and interfaces experimentally by means of in-situ solid state nuclear magnetic resonance (NMR, Prof. Gerd Buntkowsky, Department of Chemistry) and theoretically by atomistic modelling (Prof. Karsten Albe, Department of Materials and Earth Sciences).

Further members are the Karlsruhe Institute of Technology – Helmholtz Institute Ulm, University of Birmingham, University of Warwick, Uppsala University, the Research Institute CEA, Fraunhofer ISE, Institute for Energy Technology IFE, the Slovak Academy of Sciences and various industrial partners. An advisory board from industry will support the consortium in the implementation of the innovative sodium solid-state batteries.


The SIMBA project is funded through the Horizon 2020 call LC.BAT-8-2020: “Building a Low-Carbon, Climate Resilient Future: Next-Generation Batteries”. SIMBA starts January 1, 2021, and will be funded for 42 months.

The project is funded by the European Union (Grant Agreement N. 963542).

Projects (Dissertations)

Dissertation: M.Sc. Marco Melzi d´Eril

Supervisors: Prof. Ralf Riedel , Dr. Magdalena Graczyk-Zajac

With the growing production of renewable energies, also the demand of storage system arises. Thus, taking advantage of the high energy density of metallic Na could provide a cheap and reliable energy storage technology. Nevertheless, practical application of NMB (Sodium Metal Batteries) is still challenging and a continuous research is needed to overcome issues like the dendrites formation, poor reversibility and low coulombic efficiency.

The focus of this PhD thesis is the design and optimization of the morphology and microstructure in highly porous ceramics (silicon carbide/carbon) which will serve as a matrix for sodium-metal plating in NMB (Sodium Metal Batteries). Such a “host-free” system should bypass all the issues related to the slow kinetic of the intercalation process, providing at the same time a high capacity. Further the ceramic matrix will support a controlled plating of the metallic sodium in the pores, hindering the formation of dendrites and providing therefore a stable and reversible mechanism limiting the volume expansion.

The tuning of the material is achieved by:

1) Tailoring porosity controlling the size of crosslinking agents and the number of Si-H groups in the precursor.

2) Optimizing the electrochemical properties via tuning of porosity and microstructural properties.