Fraunhofer researches small rechargeable batteries using wood waste
Fraunhofer IKTS aims to make battery production more sustainable and increasingly replace critical raw materials. Wood is a potential material.
The vessel contains hard carbon made from lignin, a material that can be used in batteries to reversibly store sodium ions.
(Image: Fraunhofer IKTS)
A research team from the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS) and Friedrich Schiller University Jena is using the biopolymer lignin, found in wood residues, for use in a sustainably developed sodium-ion battery. Lignin is intended to help reduce Germany's dependence on critical raw materials for batteries and make battery production and batteries more environmentally friendly. The research is being conducted as part of the project “ThüNaBsE,” funded by the European Social Fund project “ThüNaBsE.”
Lignin is a major component of wood, found in the cell walls of trees, providing stability and compressive strength through lignification. Approximately 20 to 30 percent of the dry mass of woody plants consists of lignin. This material is abundantly available, primarily as a waste product from paper and pulp production.
Battery components from lignin
Lignin is largely composed of hydrocarbon building blocks that can be chemically utilized. One possibility is to use the material for the electrodes of sodium-ion batteries. In this way, scientists aim to increasingly forgo previously used critical metals and are testing the extent to which the fluorine content in electrodes and electrolytes can be reduced or even completely eliminated.
In their battery, the researchers are producing negative electrodes for the batteries from lignin. For this, Fraunhofer IKTS is collaborating with Mercer Rosenthal GmbH, a company specializing in the production of pulp and wood-based biochemicals. The company thermally converts the lignin into carbon in the absence of air. This carbon is then processed into electrodes.
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At the Institute of Technical Chemistry and Environmental Chemistry at Friedrich Schiller University Jena, lignin is converted into hard carbon through thermal processes. This material is suitable for reversibly storing sodium ions. It exhibits high electrochemical performance and good cycle stability.
The positive electrode is also to be replaced with a more environmentally friendly variant. It is made from Prussian blue analogues, which are non-toxic iron compounds with sodium-ion storage properties are environmentally compatible and readily available on the market.
The scientists at IKTS and Friedrich Schiller University have already built initial battery demonstrators from the materials. The batteries are currently being tested. “The laboratory cell has not yet significantly degraded after 100 charge and discharge cycles. The goal is to demonstrate 200 charge and discharge cycles for the 1 Ah full cell by the end of the project,” says scientist Dr. Lukas Medenbach from IKTS Arnstadt.
Potential applications
These batteries can later be used as stationary or mobile storage. However, they cannot be recharged very quickly. Furthermore, the energy and power demands of consumers should not be too high. The scientists mention small vehicles up to 45 km/h and forklifts as potential applications.
After the project, the researchers intend to further scale up the technology. More participants will then be involved to bring the technology to market readiness. In addition to Fraunhofer IKTS, Friedrich Schiller University Jena, and Mercer Rosenthal GmbH, Glatt Ingenieurtechnik GmbH, IBU-tec Advanced Materials AG, EAS Batteries GmbH, and Petrochemical Holding GmbH from Vienna are also involved.
(olb)
