Contact person: Jannes Müller und Markus Nöske
The storage of electrical energy is nowadays used in many fields. Lithium ion batteries are often used for these applications. In particular in the mobility sector an increase in cell capacity offers the potential to increase the operating range of electric vehicles significantly. In the BMBF project SiGgI (“Silicon Graphite goes Industry”) investigations regarding the increase of the anode capacity due to the use of novel active materials based on silicon-carbon composites (Si/C composites) will be carried out. Compared to conventional graphite anodes, silicon-containing anodes offer the potential to increase the theoretical capacity by a factor of 10. Various scalable process routes (see figure below) for the production of the Si/C composites and their influences on the material structure and performance will be analyzed. The starting point of the process routes is the comminution process in a stirred media mill. Therefore the components are comminuted at first separately. The goal is, to crush silicon down to the nanometer range. The influence of process and formulation parameters on the properties of the nanoparticulate silicon suspensions have to be characterized. In addition, the delamination of graphite to graphene, which is a promising carbon component for the preparation of Si/C composites, is examined in the stirred media mill.
In the second project phase the multicomponent comminution of silicon and carbon components will be investigated in detail and the obtained material structures will be analyzed. The aim is, to establish the processing of the final coating suspension for the electrode preparation directly in the stirred media mill.
Fig.: Process strategies for the production of novel silicon-carbon composites for the use in advanced lithium-ion batteries
In addition, the processing of the previously prepared silicon nanoparticles to silicon carbon composites and directly to electrodes in lithium-ion batteries is investigated. The production of composites by spray drying and fluidized bed processes will be examined closely. The composites are then processed to form the electrode coating. This will be done on a laboratory scale coater as well as on a pilot scale coater. For the coating process the formulation of the anode slurry is of particular interest because the composites must be transferred intact into the electrodes. The prepared electrodes are examined in particular with regard to their structure and the electrochemical performance.