A central focus of research for the "Cell and Process Development" working group is the development and optimization of recipes and manufacturing processes for electrode foils at the pilot scale. From a technological point of view, lithium-ion batteries and high-performance capacitors for mobile applications are of particular interest. Commercially available active materials, binders and additives, as well as IKTS-owned active materials (e. g. LiNi0.5Mn1.5O4) are processed so as to obtain electrode slurries and pastes, and applied onto current collector foils for research purposes. Thus, for example, ceramic functional layers can be applied to existing LFP electrodes in a further tape-casting step, replacing the separator component. For PEM fuel cells, a galvanic electrode coating process with reduced Pt catalyst quantities is being developed and scaled up with IKTS-internal working groups.
Beside the recipe, the structure and morphology of the electrodes have a significant effect on the cell’s properties and performance parameters. In order to systematically optimize the electrode design, IKTS uses empirical, knowledge-based approaches as well as model-based methods, developed at Technische Universität Dresden and validated for IKTS electrode development in joint research projects. Especially when it comes to producing electrodes with a high storage capacity load, it is possible to use simulation and optimization efforts to accurately identify the electrode’s specific design parameters (porosity, coat thickness, particle distribution). This allows the maximum achievable rate capability to be translated into a real electrode design in terms of manufacturing technology. It allows to translate the best possible current load rating into a real electrode design in terms of manufacturing technology.
In general, the long-term stability and performance of the electrodes can be improved significantly by selecting the appropriate process parameters, resulting in advantages in terms of efficiency and quality. Among other things, typical developments focus on:
- Reproducible slurries and paste production at pilot scale up to 10 kg
- Prevention of gas inclusions, cross-contamination and agglomerates
- Substitution of organic solvents by water-based solvents for improved environmental compatibility of the manufacturing process
- Optimal electrode adhesion and binder distribution after drying
- High coating speeds through roll-to-roll (R2R) processes
- Uniform surface quality (without cavities, agglomerates, creases)
- Minimized variations in layer thickness for large-format cells
- Uniform, continuous compression in the calender
Building on its experience with ceramic tapes, the working group uses extensive know-how from slurry production and pre-industrial casting and extrusion processes. This specific know-how is available for clients who intend to bring new materials from pre-development into serial production and want to identify or validate the technological process parameters beforehand in the Battery Technology Application Center, in manufacturing conditions similar to those prevalent in industrial production.
- Model-based electrode development and optimization according to client’s specification
- Manufacture of electrode slurries and pastes at pre-industrial scale
- Development and optimization of innovative manufacturing concepts for electrode production
- Performance of material and coating tests of electrode foils using the classical casting process (doctor blade or slot die) or cold or hot plastic sheet extrusion under dry room conditions
- Upscaling of manufacturing processes and technology transfer to the client
- Construction of prototypical, mono- and bipolar multilayer cells
- Electrochemical evaluation and analysis of test cells
- Feasibility studies and consulting in the field of process development