The breakthrough in electric mobility (e.g., cars) and portable electrical devices (e.g., cell phones and laptops) would not have been possible without lithium-ion batteries (LIBs). Lithium is one of the main elements of these batteries owing to its favorable properties (e.g., lightest metal, highest electrochemical potential, and highest energy density of all metals). It can be extracted from salt lakes and ores, whereby the extraction of lithium from salt lakes requires large amounts of water and is time-consuming (18–24 months). The extraction of ores is an expensive and energy-intensive process. The continuously increasing demand of LIBs will lead to a forecasted lithium shortage of about 47 million tons by 2050, if lithium is not recycled1. All of these factors lead to the urgent need of developing a recycling concept to recover lithium in high purity. Hydrometallurgical processes have been intensively studied, which have the potential to recycle more than 90% of spent battery raw materials. The recycling of valuable metals from LIBs has the advantage that the materials can be directly reused. Within this work, we demonstrate a selective sustainable hydrometallurgical leaching process to recycle lithium using (carbonated) water as sustainable leaching agent. Furthermore, the continuous precipitation of lithium carbonate is studied.
The selective leaching of lithium from black mass (shredded electrode material, NMC cathode and anode material) is done in batch-mode using water2 and carbonated water without any oxidizing agents. The influence of different process parameters (temperature, solid/liquid-ratio and mixing rate) and ultrasound are investigated. To prove the concept, the leaching process is implemented in a Taylor-Couette Disc Contactor, where a leaching efficiency of lithium of 76% and a selectivity for lithium of 96% is achieved. Afterwards, the continuous precipitation of lithium carbonate is studied, optimizing process parameters with regard to the precipitation efficiency of lithium and the particle size distribution.
This work presents a promising concept for the direct recycling of lithium carbonate and using it as raw material for new LIBs. Furthermore, the use of oxidizing agents (e.g., H2O2) is minimized and the energy consumption is reduced because no pretreatment is required.