Syntheses of nickel-rich active materials and sulfide solid electrolytes for ASSB cathodes
In recent years, All-Solid-State-Batteries (ASSB) have gained importance for energy storage systems, because of their potentially superior characteristics compared to conventional lithium ion batteries. In order to produce cells with competitive properties, such as high energy density as well as high thermal, and mechanical stability, the choice of materials at the beginning of the value-added chain of a battery is a main key. Thus, the focus of our work is to evaluate and establish new process strategies to produce and pre-treat active materials as well as solid electrolytes. For example, producing nickel-rich active materials for ASSB systems is a current topic in research and industry. We have the goal to establish and optimize a new precipitation process to synthesize such active materials. Using a stirred media mill with suitable setting parameters for optimized flow characteristics and residence times should result in an efficient process, which can easily be scaled up for industrial application. Furthermore, processes will be developed to modify the surface of active materials to especially enhance their conductivity and to increase the chemical stability against solid electrolytes. Sulfides have attracted broad interest as solid electrolytes due to their high Li+ conductivity and compliant mechanical properties. Their synthesis can be performed by high energy ball milling. However, the reaction mechanisms are still not well understood. Therefore, it is highly important to acquire extensive knowledge of the process-product interactions. Our main aim is the upscaling of the mechanochemical syntheses of sulfidic electrolytes while optimizing the process by systematic variation of parameters, such as grinding media ratio, grinding media size or temperature. The starting point for this development is the synthesis of sulfidic glasses in planetary ball mills, which is currently taking up to 25 hours for complete amorphization. Based on the obtained insights, the synthesis procedure will be adapted for the upscaling in suitable mill types such as vibrating mill and stirred media mill. The combined work on the scale-up of active material and solid electrolytes should enable high performance and low cost cathodes and thus facilitate the industrial production of ASSB.