Browsing by Author "Kaas, Alexandra"

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Open Access
Influence of a pyrolysis at different temperatures on the mechanical recycling efficiency of Li-ion batteries
(Technische Universität Bergakademie Freiberg, 2024-12-12) Kaas, Alexandra; Wilke, Christian; Born, Jannik; Ahuis, Marco; Kwade, Arno; Peuker, Urs
The integration of a pyrolysis stage into the mechanical recycling process of Li-ion batteries is supposed to improve the decoating of the electrodes, the recovery of valuable components and the overall quality of the products. The effectiveness of the pyrolysis process depends on the applied temperature as the various components of a Li-ion battery melt, evaporate and decompose at different temperatures. The decomposition temperature of the cathode binder is a crucial factor in the thermal mechanical recycling process. Temperatures below this threshold have a negative impact on the recovery rates, as the melting of binder and plastics reduces the efficiency of the recovery process. Conversely, higher temperatures facilitate the recovery of the cathode coating metals (Ni, Co, Li) into the black mass. The majority of the metals (92-98%) are recovered and, following hydrometallurgical treatment, can be reused for cell production, thereby closing the loop and reducing the consumption of raw materials and enhancing the sustainability of batteries. Moreover, the decomposition of the organic components, including binders and plastics, improves the quality of the products, thereby reducing the necessity and extent of further treatment.
Open Access
Influence of shredder and mill settings on the material recoveries and product qualities of a two-stage mechanical recycling process of automotive lithium-ion batteries
(Technische Universität Bergakademie Freiberg, 2025-03-12) Kaas, Alexandra; Wilke, Christian; Peuker, Urs
For a two stage shredding and milling process the yield of black mass and the elemental recovery of critical elements Ni and Li s investigated. I can be shown that the quality of the products resulting from the mechanical recycling of lithium-ion batteries significantly depends upon the parameters employed during the shredding process. Modifications to the settings have the potential to exert a considerable impact on the particle size, liberation of composites and de-coating of electrodes. The discharge grid size employed during the first shredding step shows a significant influence on the downstream separation behaviour of the casing material and separator foil. The mill speed utilised during the second comminution step determines the separation achieved between the cathode and anode. A reduction in grid size employed during the first shredding stage results in an increase in black mass yield, although the recovery of the casing is diminished. In total Ni recovery for all setting combinations is similar, a lower recovery in the first shredding step is compensated by a higher recovery after the second comminution. It was observed that an overall increase in the mill speed above 1750 rpm resulted in elevated levels of copper contamination within the black mass. The influence of eleven distinct combinations of shredder and mill settings on the black mass yield and its composition, the recovery of the separator foil and the casing, as well as the separation behaviour of the anode and cathode, were investigated.
Open Access
Supplementary information to the publication “Influence of foam composite in lithium-ion battery packs on their mechanical recycling”
(Technische Universität Bergakademie Freiberg, 2025-05-23) Rademacher, Paul; Kaas, Alexandra; Wilke, Christian; Peuker, Urs A.
Supplementary data to the following paper. Lithium-ion batteries (LIB) make an important contribution to the energy transition as energy storage devices for mobile and stationary applications. The recovery of the valuable materials contained in the lithium-ion batteries after their end of life is of central importance for the development of a circular economy in line with the concept of sustainability. Mechanical recycling is to be seen as a first step in this process. With processes for the mechanical recycling of LIB that have already been successfully developed and implemented, it is possible to recover most components of a LIB i.e., the materials of the anode, cathode and separator foils as well as the casing. The concentrate of the coating of the electrode foils, which is called black mass, becomes an intermediate product for hydrometallurgical recycling processes for the recovery of lithium, among other materials. Some OEM of the automotive industry are about to introduce cell-to-pack-technologies, in which individual LIB-cells are fixed and stabilised in their position inside the large battery pack with the aid of a foam material, thereby adding further materials to the battery pack. The effects of the foam on the recycling are not known yet. Within the scope of this experimental work, several technological variants to enrich and separate the foam as an individual material fraction were investigated. The holistic aim is to minimise contamination from the foam in the valuable fractions. Two different types of foam and their effect on the purity of the recycling products were analysed.
Open Access
Supplemetary information and dataset to the publication "Evaluation of the tensile adhesion strength of cathode coatings from spent lithium-ion batteries using a centrifugal method"
(Technische Universität Bergakademie Freiberg, 2025-12-22) Dahl, Konstantin; Löwer, Erik; Kaas, Alexandra; Peuker, Urs A.
Lithium-ion batteries are essential for the transition to renewable energy and electrified transport. As their use continues to grow, efficient and sustainable recycling processes are needed to recover valuable materials from spent battery cells. Such industrial recycling processes often rely on hydrometallurgical extraction of valuable metals and require selective removal of cathode coatings from metallic current collector foils beforehand. The efficiency of this decoating strongly affects the yield and purity of the recovered material fractions. In parallel, direct recycling concepts that aim to preserve the structure and functionality of cathode active materials for re-use depend even more critically on controlled decoating with minimal damage to the coating materials. In both cases, the adhesion between these coatings and their substrate foils is a key parameter that governs how easily active material layers can be detached and how efficient the resulting streams of active material and current collector foil can be separated. In this context, a centrifugal testing method was developed to quantify the tensile adhesion strength of cathode coatings and to assess fracture under defined processing conditions. The method enables a systematic evaluation of how different pre-treatment strategies, such as thermal drying, affect coating adhesion. Here it is applied to cathode foils from end-of-life NMC-111 cells thermally pre-treated in air at room temperature, 80 °C, 140 °C, 310 °C and 350 °C. Depending on the pre-treatment temperature, the fracture behavior shifts markedly between adhesive and cohesive modes.