The steadily growing sales of lithium-ion batteries also increases the interest in raw material recycling of the used resources. Financial incentives and legal requirements are the driving forces in this industry. The aim of this research is to optimize existing and develop new industrial recycling processes in order to enable environmentally friendly and profitable recovery of the metals into the respective manufacturing processes. The various stages of the recycling processes can be roughly divided into preprocessing, mechanical, hydrometallurgical and pyrometallurgical processes. Pretreatment means any process that does not change the structure of the lithium-ion battery (e.g. sorting by battery type from mixed waste). Mechanical processing uses various techniques to expose, classify, and concentrate materials without changing their chemistry. After mechanical processing, refining is carried out by hydrometallurgical, pyrometallurgical or combined steps. Pyrometallurgy refers to processes at elevated temperatures in which redox reactions take place to melt and clean metals. In the meantime, hydrometallurgy serves to leach valuable elements from a solid matrix and modify them by precipitation or crystallization. Since these techniques appear to be extremely resource-intensive, there exists a strong impact of economic constraints. As part of the research on lithium-ion batteries, a new combination of process steps was developed, which enables selective recovery of a cobalt-nickel mixed product and lithium, while the removal of existing impurities takes place in selective precipitation steps. This process is characterized by the specification of optimized parameter combinations in the individual leaching and precipitation steps, which ensures the best possible recovery rates of the valuable metals.