In the future, large quantities of end-of-life lithium-ion batteries will be sent for recycling. Current mechanical recycling processes focus on the recovering of the “black mass”, which often results in material losses, especially for aluminum. In response, mechanical processing techniques like zig zag air separator, Fe-separator, impact mill and density table, as well as X-ray sorting have been developed to enable early separation and targeted recovery of materials such as copper, iron and aluminum, and to ensure their integration into specialized recycling pathways. In the BMBF-funded DemoSens project (funding code 03XP0314A), this advanced mechanical treatment approach was tested on thermally pre-treated shredded modules (without black mass). These included module housings and peripherals made of aluminum, copper, and steel, as well as the aluminum and copper electrode foils. In addition, the aluminum electrode foil contained black mass residues.
From these tests, a model was developed to show the separation efficiencies of the advanced mechanical treatment, the recovery rate of the materials, and the material quality of the target output streams. For the recovery of the copper and aluminum electrode foils, the use of an impact mill followed by a density separation table is recommended. The sorting efficiency for copper and aluminum is about 93 – 99 %, which means that only a small amount is incorrectly sorted. Also, 95% of black mass residue can be separated. Solid aluminum can be sorted from a size of 4 mm using X-ray sorting technology, with more than 90 % recovery. However, due to process-related limitations in the shredding process, a large proportion (~40 %) of the particles can be smaller than 4 mm, so the overall recovery rate for the total amount of solid aluminum is 55 %. For the aluminum foil from the electrode, the recovery rate in the developed process is 70 % and for copper 97 %. In addition, it can be shown that advanced mechanical processing results in higher qualities of the material streams that can be fed into a further metallurgical process.
Advanced mechanical processing is a comprehensive processing chain that has the potential to increase the recycling efficiency of battery recycling. However, it should be noted that each additional sorting step requires additional effort (including energy and costs, which will be further investigated). Processing generally depends on the input, so that treatment of battery modules with a lower material variety result in fewer processing steps. In contrast, the treatment of inert or wet-processed batteries without thermal pre-treatment will be more complex, e.g. due to the treatment of waste water and the battery separator.