Triggered by environmental and economic reasons, different techniques for the recycling of lithium-ion batteries (LIBs) have been studied in the recent years, which include pyrometallurgical, hydrometallurgical and direct recycling processes. The hydrometallurgical recycling seems to be the most promising technique with potential economic viability in order to achieve high recovery rates and high purity of recycled material from LIBs. In this master thesis a hydrometallurgical approach for the recycling of LIBs is studied in the context of a secondary copper refinery in order to expose possible emerging synergetic effects. The sulfuric acid leaching of the black mass from LIBs with an electrolyte bleed stream of a copper refinery is selected as the binding point between the two systems. Two battery packs from the e-mobility sector are fully characterized in terms of material composition and physical properties. Prior to the hydrometallurgical process a set of pretreatment steps, which include discharging, disassembling, pyrolysis, shredding and sieving are followed in order to obtain the black mass for the leaching experiments. The leaching media is adjusted with nickel, copper, arsenic, iron and calcium impurities to simulate the composition of an electrolyte bleed stream of a copper refinery after the third stage of liberation. Through the study of the leaching parameters of temperature, solid-to-liquid ratio, sulfuric acid concentration, hydrogen peroxide concentration, leaching time and copper concentration, a statistical experimental design has been conducted in order to determine the optimal leaching conditions. Even though the ideal leaching point lays on the edges of the experimental design, the results prove the feasibility of performing the leaching of LIBs with spent acids from an electrolyte bleed stream. Furthermore, a hypothetical copper refinery is presented in order to establish a mass balance with a LIB recycling line thanks to the material characterization of the LIB packs and the results of the optimized leaching parameters.