Fraunhofer ISE and IKA have developed a solvent-free and PFAS-free electrode coating process for sodium-ion batteries
The process could reduce capital costs by at least 15% and operating costs by 10% to 20% compared with conventional wet coating
Researchers have produced electrode films with thicknesses ranging from 80 to 180 µm, with pouch-cell scale-up planned
Germany’s Fraunhofer Institute for Solar Energy Systems ISE, in collaboration with equipment manufacturer IKA, has developed a dry-coating process for sodium-ion battery electrodes that eliminates the need for solvents and per- and polyfluoroalkyl substances (PFAS). Developed under the LAENDLE research project, the process aims to reduce manufacturing costs, energy consumption, and the environmental impact of battery production.
Battery electrodes are generally manufactured using a wet-coating process. This involves mixing electrode materials with solvents, applying the mixture to a metal foil, and drying it. Dry coating avoids solvents and reduces the energy needed for manufacturing. However, some dry-coating methods still rely on PFAS-based chemicals to bind the electrode materials together.
Fraunhofer ISE and IKA developed an alternative process using continuous kneading to prepare the electrode material without PFAS-based binders. The researchers identified two classes of PFAS-free polymer binders suitable for dry coating. At the Fraunhofer ISE Center for Electrical Energy Storage, the team produced freestanding electrode films that can be attached to a metal current-collector foil. The film thickness can be adjusted between 80 and 180 µm, although other thicknesses are also possible.
The new process also eliminates the need for an additional bonding agent on the metal foil. This removes a manufacturing step and reduces equipment and energy requirements. According to Fraunhofer ISE, the process can be integrated into existing dry-coating production lines without changes to subsequent manufacturing steps.
Fraunhofer ISE estimates that the process could reduce capital expenditure (CapEx) per production line by at least 15%. Operating expenditure (OpEx) could be approximately 10% to 20% lower than that of conventional wet-coating lines. The institute also estimates that eliminating several manufacturing steps, including drying, calendaring, and the application of bonding agents, could reduce energy consumption and associated CO₂ emissions by around 50%.
The next phase of the LAENDLE project will focus on scaling up the technology to pouch-cell production at the institute’s research facility. Researchers also plan to further reduce the amount of binder used in the electrodes to levels commonly found in commercial battery manufacturing.
According to project manager Dr. Oliver Fitz of Fraunhofer ISE, simplifying the coating process and reducing equipment requirements could make battery electrode manufacturing more accessible to small and medium-sized enterprises. The project is funded by the Baden-Württemberg Ministry of Economic Affairs, Labor, and Tourism, and is scheduled to continue until June 2027.