The number of electric and hybrid electric vehicles (EVs and HEVs) as an alternative to internal combustion engines (ICE) has been rapidly growing for the last five years. When the electric cars or their traction batteries reach their end of life (EOL), an efficient recycling (from a material as well as an energetic point of view) is important to ensure sustainability and to close the materials cycle. Combining mechanical processes like crushing, screening and sorting, valuable metals such as copper, steel and aluminium can be recovered. Key to this is a sufficient liberation of components by crushing and grinding. This study focuses on safety issues of mechanical processing and on the correlation between the material composition and the required specific mechanical energy input necessary to break the Li-ion battery cell apart. Investigations on the crushing behaviour of the single components (anode-, cathode- and separator foils as well as housing materials) and entire Li-ion battery cells were done. Measured specific mechanical stress energies for the crushing of complete battery cells are compared to calculated ones. Inputs to the calculation are the measured specific stress energies of the single components comminution. As a result, the comminution can be adjusted and optimized in order to keep up with the rapid development of Li-ion batteries. With respect to the recyclability of Li-Ion battery cells, recommendations for a design appropriate for recycling are made.