Developing a New Generation of Sodium Batteries

Stationary Energy Storage from Readily Available Resources – The KeNaB-ART Project.

Resources are limited and today's battery materials are often criticized for being dangerous and unethically sourced. Against this background, how interesting the idea of being able to produce energy storage devices from harmless and universally available materials sounds! We are exploring this possibility together with partners in the "KeNaB-ART" project – a battery made of sodium.

The IBU-tec R&D team, together with the project partners Rauschert Heinersdorf-Pressig GmbH, Fraunhofer IKTS and EL-Cell GmbH, is investigating the potential of solid sodium electrolyte batteries. The name of the project: KeNaB-ART, short for the German: "Ceramic-based Sodium Battery with Beta-Aluminate for Applications above Room Temperature".  The project is funded by the German Federal Ministry of Education and Research (BMBF) as part of the "Battery 2020 Transfer" funding initiative for the development of new ceramic sodium batteries (03XP0404A).

The sodium battery is considered one of the most promising approaches in the search for economically and ecologically viable alternatives to conventional lithium. This type of battery is based on a solid electrolyte made of a special sodium-ion conductive ceramic as the heart of the battery cell.

The cells designed in the project consist of three main components: the ceramic solid electrolyte, a liquid metal anode and the sodium-ion cathode. From a technical point of view, the structure is conceivable as a combination of two conventional battery types, the ZEBRA and the lithium-ion (LIB) battery, combining the advantages of both. The result is a lower fire load compared to conventional liquid electrolytes, i.e. a greatly reduced hazard potential. The metallic sodium anode also has a very high achievable energy density, as no additional carbon is required, as is the case in commercial battery cells.

Organization of the Sodium Battery Development

KeNaB-ART takes on the technical challenge of developing a marketable solid-state battery cell: from raw materials to a ready-to-install product, in order to contribute to the production of more sustainable, stable and safer cells with high energy density in Germany.

Our three partners come from the production of solid electrolyte ceramics, the physicochemical and electrochemical analysis that produces the cells and tests their performance, and the manufacturer of the measurement cell systems. IBU-tec is involved in the development and production of the cathode active material in a combination of process steps in the rotary kiln and our in-house pulsation reactors.

In the initial stages of the project, a battery system was selected, performance parameters were determined, and a specific sodium cathode active material was selected: sodium manganese oxide. Despite possible performance advantages, the decision was actively made against materials containing cobalt and nickel due to their environmental and health hazards, as well as the complicated resource situation.

During the development of the electrode and electrolyte materials, a regular exchange of results with the project partners facilitated the further development and performance optimization of the cell components.

Status of the KeNaB-ART Project

After two years of project work, we have now achieved our milestones: The development and production of a phase-pure sodium manganese layer oxide cathode active material within the required specifications for the desired performance. The results will be presented to the public at the Battery 2020 Transfer status seminar in autumn.

Next Steps and Potential Applications of the Sodium Battery

The next development steps in the project will be to verify and further optimize the cycle stability of the cathode. If satisfactory results and sufficient performance are achieved, a scale-up for the production of the cathode active material will follow, while maintaining the properties achieved in the pilot stage. This would be followed by energy optimization of the process to reduce potential production costs.

We see potential applications in stationary energy storage systems that do not require cooling at operating temperatures above 100°C, even in systems above 500 kWh.