In-Depth Studies on the Stability of Cathode Active Materials in Coated Electrodes from Lithium–Ion Batteries in Aqueous Media as Part of Functional Recycling Technology

With the increasing prevalence of lithium–ion batteries, the recycling of battery materials is becoming increasingly important. Functional recycling represents a promising approach in this context, one that is often based on aqueous treatment steps. This study examines the aqueous treatment of positive electrodes coated with various cathode active materials and their mixtures. To this end, the electrodes were leached in two different broad-range buffer systems in the pH range of 5 to 11. The investigations focused on the temporal evolution of the pH value, the time-dependent leaching of the active material components, and the dissolution of the aluminum current collector. The results show that process parameters, particularly the initial pH value, the treatment duration, and the composition of the process medium, influence both the leaching of the active materials and the corrosion of the aluminum current collector. Furthermore, the coated electrodes studied show significant differences in the stability of the active materials, which sometimes deviate from the properties of the respective pure active materials described in the literature, suggesting additional interactions within the electrode structure. The results highlight the need for targeted process optimization to create the conditions for the successful functional recycling of active materials from lithium–ion batteries.