German scientists develop a lignin-based sodium-ion battery

Against the backdrop of the global race for battery raw materials (lithium, nickel, cobalt, and graphite), a signal is coming from Germany that could, in the long term, change the rules of the game. A team of researchers from the Fraunhofer Institute for Ceramic Technologies and Systems and Friedrich Schiller University in Jena has presented a prototype sodium-ion battery in which the anode material is hard carbon derived from lignin.

From industrial waste to strategic battery material

Lignin is one of the most abundant organic polymers on Earth. Alongside cellulose and hemicellulose, it forms the cell walls of plants. On an industrial scale, it is generated as a by-product in wood processing. For decades, it was treated mainly as low-quality fuel or technological waste. Meanwhile, its chemical properties (the presence of redox groups and the possibility of being converted into conductive carbon) make it an attractive raw material for electrochemistry.

In the Fraunhofer project, lignin supplied by Mercer Rosenthal GmbH was subjected to carbonization under oxygen-free conditions, resulting in hard carbon with a structure favorable for the reversible intercalation of sodium ions. Unlike graphite (commonly used in lithium-ion batteries), hard carbon better accommodates the larger sodium ions, which have limited mobility in graphite structures.

Sodium instead of lithium

Sodium-ion batteries have for several years been seen as a potential complement (rather than a full replacement) to lithium-ion technology. Sodium:

• is many times more geographically abundant than lithium,
• is not subject to such strong geopolitical tensions and mining concentration,
• allows for lower raw material costs for energy storage systems,
• is attractive for grid-scale applications.

In the European context, the development of sodium-ion battery technologies fits into the broader EU strategy of technological sovereignty. The Fraunhofer project has a clearly stated goal: reducing dependence on critical raw materials and developing cheaper, safer, and more sustainable battery chemistries.

Test results and potential applications

The research team built full cells with a capacity of 1 Ah, which underwent testing at Fraunhofer IKTS test centers in Arnstadt and Hermsdorf, as well as at the University in Jena. After 100 charge–discharge cycles, no significant degradation of electrochemical parameters was observed. The goal of the project is to reach at least 200 stable cycles by the end of the research program.

Although 100–200 cycles is far from commercial maturity, in the context of the early stage of development of sodium-ion technologies based on bio-derived electrodes, this is a promising result. The researchers openly indicate that the target application areas are stationary energy storage systems and selected mobile applications, where:

• low material cost is important,
• resistance to temperature fluctuations matters,
• energy density requirements are less restrictive than in premium electric mobility.

It is also worth noting the organizational model of the project. Regional industrial companies from Thuringia and Austria are involved in the initiative — from material producers (IBU-tec advanced materials AG), through process engineering (Glatt Ingenieurtechnik GmbH), to battery system manufacturers (EAS Batteries GmbH). This setup represents an attempt to build a regional value chain for new battery technologies.

The lignin-based sodium-ion battery is still a research project today, but it is also a clear signal about the future direction of energy storage.