Researchers Develop Sustainable Sodium-Ion Batteries from Lignin

Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS) and the Friedrich-Schiller-University Jena have embarked on a significant project to develop sustainable sodium-ion batteries using lignin, a by-product from the wood and pulp industry. This initiative, part of the Thuringia Sodium-Ion Battery for Scalable Energy Storage (ThüNaBsE) project, addresses the growing demand for safe, cost-effective, and environmentally friendly energy storage solutions.

The project proposes a novel battery system that utilizes lignin as a key component. Traditionally, lignin, a biopolymer that provides stability to wood, is often burned as a waste product in the paper industry. Researchers aim to transform this underutilized resource into high-performance electrodes for sodium-ion batteries. The initiative not only seeks to reduce dependence on critical raw materials, such as lithium and cobalt, but also emphasizes the importance of utilizing locally sourced, recyclable materials.

Lukas Medenbach, a research scientist at IKTS, highlighted the project’s goals: “We want to avoid critical metals such as lithium, cobalt, and nickel in the battery value chain. We also aim to minimize the fluorine content in the electrodes and electrolytes.” The focus on lignin processing is expected to yield electrodes that meet high-performance standards while being environmentally sustainable.

Innovative Use of Lignin

The lignin used in the project is supplied by Mercer Rosenthal GmbH. Researchers will thermally convert the lignin into carbon under inert conditions, which will then be further processed into electrodes. Cornelius Dirksen, a colleague of Medenbach, explained, “The structure of this hard carbon is very suitable for the reversible storage of sodium ions. Hard carbon boasts high electrochemical performance, good cycle stability, and low acquisition costs, especially if obtained from sustainable raw materials.”

The positive electrode will utilize Prussian Blue analogs, non-toxic iron compounds that have been recognized for their good availability and compatibility with sodium-ion storage. The first small demonstrator cells are currently under construction and testing at the battery test center in Arnstadt, as well as at the Friedrich-Schiller-University in Jena. The researchers are complementing their laboratory work with realistic, multi-physical simulations.

Early results from the project are promising. According to Medenbach, “After 100 charging and discharging cycles, the lab cell shows no significant degradation.” The team aims to demonstrate up to 200 cycles for the 1-Ah full cell by the conclusion of the project.

Applications and Future Prospects

Once fully developed, these lignin-based sodium-ion batteries could find applications in both stationary and mobile energy storage, particularly in settings where fast charging is not essential. Potential uses include microcars, which have a speed limit of 45 km/h, and warehouse logistics vehicles like forklifts.

As the project progresses, the consortium plans to scale the technology further, moving towards higher levels of technology maturity. Additionally, the ThüNaBsE project is committed to fostering the growth of junior researchers in Thuringia, involving several doctoral candidates in energy and battery research.

The development of sodium-ion batteries using lignin not only has the potential to enhance energy storage solutions but also represents a significant step in sustainable practices within the battery industry.