The safety of lithium ion battery (LIB) cells can potentially be significantly improved by eliminating the use of combustible electrolyte fluid in all-solid-state batteries (ASSB). A dense solid electrolyte layer allows the use of lithium metal as an anode to increase the energy density by up to 70 % compared to conventional LIB. Despite promising results on a laboratory scale, there are currently only a few published papers on upscaling. Especially the cell, stack and housing design of large-format ASSB are still unclear.
This poses major challenges for production technology in the processing of the new cell materials: These include the achievable layer thicknesses for competitive energy and power densities and the processing of adhesive and reactive lithium metal, as well as targeted surface modification and production of suitable protective layers to prevent undesired side reactions. The use of ceramic materials requires novel production processes. Many solid electrolytes are very sensitive to humidity and have to be sintered at high temperatures. The aim of the "ProFeLi" project is therefore to provide a comprehensive view of the entire production value chain for the manufacture of ASSB. On the anode side, the production and processing of thin lithium metal layers and protective layers are to be researched, whereas for cathodes and solid electrolytes the focus is on the investigation of multilayer systems. In particular, the atmosphere (dryness, inert gas) necessary for the processing of the novel materials will be investigated. Furthermore, stacking and housing concepts for ASSB are to be developed, whereby the volume expansion of the active materials during the loading and unloading process plays a major role and is to be taken into account with simulation support. In order to enable a bipolar cell stack design, suitable current collector foils are being developed which are stable to both anode and cathode potential. The final goal of the project is the construction of a functional demonstrator for the production of ASSB. To this end, the necessary plant technology for cell assembly will be developed and built, then ASSB will be manufactured and tested on the basis of automotive requirements.
The consortium consists of two German research institutions (Technical University of Munich: Institute for Machine Tools & Industrial Management (iwb) and Chair for Electrical Energy Storage Technology (EES), Forschungszentrum Jülich GmbH) as well as seven German companies (Brückner Maschinenbau GmbH & Co. KG, ElringKlinger AG, GS GLOVEBOX Systemtechnik GmbH, J. Schmalz GmbH, Volkswagen AG, Zwick GmbH & Co. KG).