In this project strategies for the sustainable processing of Li-ion batteries (LIBs) at the end of their service life will be developed. Therefore, the focus of this project is on the following topics: - Development of economically profitable and environmentally friendly recycling strategies, which serve to separate and clean the different battery materials, namely anode active material (graphite), cathode active material (Co, Ni), current collectors (Cu, Al), and lithium from the electrolyte. Various methods will be developed and compared, the focus will be on modification and improvement of existing hydrometallurgical processes, including bioleaching as the most environmentally friendly option. - Characterization of the recovered active electrode materials (investigation of chemical composition and structure) - Reusing the recovered active materials in new electrochemical cells (electrochemical characterization including measurements of capacity values, rate capability, stability upon cycling and investigation of lithium diffusion coefficients). Thorough basic studies on physicochemical and electrochemical properties of the recovered products are essential to evaluate their market viability. The recycling of spent LIBs is not as well-developed as the recycling of other types of batteries, and currently is focused on recovering mainly Co, Cu, Ni, Mn, Fe and Al, while recovery of other precious elements and components such as lithium or graphite still maintains in the lab-scale. That is why the basic studies improving the recycling and recovery processes are urgently needed. The battery market is estimated to grow at a compound annual growth rate (CAGR) of 12.3% over the projection period 2020-2025. By 2025 global energy storage is predicted to move into the TWh era, making it sustainably critical to fully close the waste loop as soon as possible. According to International Energy Agency (IEA) analysis and projections, by 2030 roughly 100-120 GWh of power batteries used in electric vehicles will be phased out globally each year. Moreover, the Future Waste Forecast predicts that the cumulative end-of-life volume of electric vehicle battery modules would upsurge 4 million tons by 2030, which is already more than the present worldwide recycling capacity. Therefore, battery recycling and reusing are essential ways to balance the demand for critical components such as Co, Ni or Li as well as natural graphite.