Printed batteries

Manufacturing technology for batteries of the future: With the aid of the screen printing process, Fraunhofer IFAM offers alternatives for battery production. New manufacturing concepts allow higher active material loads and greater freedom in electrode design. Completely printed batteries help on the one hand to break free from the limitations of current manufacturing technology and on the other hand to reduce the use of solvents and subsequent drying processes. Fraunhofer IFAM combines battery expertise with profound know-how in additive manufacturing. 

Green battery of the future

The topic of energy storage is currently as present as never before. The greatest challenges include increasing the specific energy density or improved environmental friendliness through the use of alternative materials and improved recycling. In order to meet these challenges, Fraunhofer IFAM is researching and developing environmentally friendly energy storage technologies and processes, as well as solid-state batteries, which are produced using new manufacturing techniques such as multiple printing using screen printing. Prototypes of additively manufactured batteries have already been developed.

Using that manufacturing route, thicker electrode layers can be produced at Fraunhofer IFAM compared to conventional electrode manufacturing, allowing higher energy densities to be realized. Furthermore, the near-net-shape printing enables new electrode designs and higher filling degrees with reduced amount of solvent can be achieved. The manufacturing process is thus not only suitable for prototype construction, but also enables application-specific "battery production-on-demand". Another important research focus of Fraunhofer IFAM is the development of new printing pastes based on more environmentally friendly nickel- or cobalt-free materials as well as water-based formulations.

Additive manufacturing processes for battery production

Our experts have extensive know-how in paste production for printed electrodes. This includes the selection of suitable materials (active materials, conductive additives, binders, rheology additives, solvents), the formulation of the paste according to the individual, specific requirements of the application of the battery cells to be produced and the homogenization of the pastes by means of suitable dispersion processes (e.g. Dispermat, three-roll mill or extruder).

The screen printing process represents one possibility for the production of thick electrode layers. Depending on the type of electrode to be produced with the corresponding electrode material and current collector substrate, the printing process parameters are optimized at Fraunhofer IFAM. These include the screen design, the type of mesh, the squeegee angle and pressure used, the printing mode, or the printing speeds.

Cell tests for characterization of the electrode layers

The performance of the created battery electrodes is then verified at Fraunhofer IFAM by building battery cells. For example, porosity is varied by post-compression, as well as the electrolytes and the separators or the electrode matching. The cell tests include capacity utilization, cycle stability, resistance, and rate capability.

Fraunhofer IFAM has the appropriate measurement technology for the electrochemical characterization of cell components. The tests can be carried out under controlled environmental conditions.

The future of the printed battery

Secondary lithium-ion accumulators or lithium-ion batteries (LiB) are nowadays among the most promising technologies for meeting energy requirements by means of mobile and stationary energy storage systems in a performance-oriented manner. Optimizations in the field of energy density aim, among other things, to reduce the necessary electrochemically inactive materials used to a minimum. In addition to the energy density of the active materials, the electrode design in particular plays a decisive role in cell performance. The main points for the electrode design are coating thickness, porosity and the active material loading of the coating. Here, printing technology can selectively increase electrode layer thicknesses, create specifically adapted layers via multiple printing and enable correspondingly good properties in terms of tortuosity, ionic as well as electronic conductivity and thus performance.  

By reducing solvents or using water-based recipes through the use of highly filled printing pastes, the environmental impact and costs can be reduced, both investment-wise and operationally, e.g. through energy savings in the drying process.

Novel designs, including at the cell level, can also produce an improvement in overall energy density, with printing technology allowing maximum flexibility and new design approaches. The shape- and format-independent design and flexibility of printed electrodes thus offer a broad design spectrum, with individualized form factor while maintaining performance, for all types of integrated energy storage technology.

New materials and technologies often require novel process and manufacturing technology. The printing of battery components up to the printed battery supports the implementation of novel battery technologies, as well as equipment manufacturers and battery cell producers and addresses various application areas.

Battery technology and innovative manufacturing processes are important competences of Fraunhofer IFAM. Under the leadership of Daniela Fenske and Mario Kohl, the two teams "Electrochemical Energy Storage" and "Functional Printing" are researching battery manufacturing using 2D and 3D printing processes. The two teams combine battery expertise with in-depth know-how in additive manufacturing and thus develop innovative manufacturing technologies for the batteries of the future. The areas of application range from mobility, energy technology and life science to maritime technologies.