The storage of energy in Li-ion batteries is the basis for the establishment of central future topics, such as electromobility or mobile devices with 5G technology. A key requirement in these fields of application is to increase the energy density of battery cells, but this is accompanied by challenges in complying with safety guidelines. Therefore, it is necessary to develop innovative technologies that improve the safety of LIBs of current and next generations, taking into account environmental and economic aspects, and at best contribute directly to an increase in energy density.
In PolySafe, processes and manufacturing methods will be developed for the use of the new technology of metal-polymer composite current collectors, which has exactly this potential and overcomes the limitations of the currently commercially established pure metal current collectors. Due to their lower density, they have a weight advantage over a metal foil of the same thickness. Furthermore, the deposition of the metal layer can be done exactly in the thickness required for electronic and thermal conductivity and can thus be adapted to the cell design. Therefore, the combination of metal layer and polymer substrate allows both weight/thickness advantages and economical use of material resources. In addition, the metal-polymer composite current collector can enable an intrinsic safety function by softening or melting the polymer in the event of an internal short circuit, thereby destroying the electrical conduction path, which ultimately limits the event locally and prevents thermal runaway of the entire cell.
The ifs' aim is first of all to determine process-relevant material properties for the design of manufacturing processes. This will enable clear requirements to be set for the composite current collector. Another focus is the development of an adapted contacting process for the metal-polymer composite current collector foil, which takes into account the insulating polymer substrate. This applies to contacting in conventional Li-ion pouch cells as well as future next-generation cells.
Federal Ministry of Education and Research
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