Direct lithium extraction (DLE) methods and their potential in Li-ion battery recycling
Usman Saleem, Andre Wilhelms, Jonas Sottmann, Hanna K. Knuutila, Sulalit Bandyopadhyay
Abstract
• Direct lithium extraction (DLE) methods to extract Li from recycling streams. • Mapping of technical aspects and suitable solute concentrations of several DLEs. • Optimization of pre-treatment route of spent EV battery recycling process. • Pyrolyzing the whole cells with dry crushing and flotation to minimize Li losses. • DLE can minimize Li losses in the recycling process. Lithium (Li) supply from secondary sources (e.g. batteries) will play a critical role in easing the demand from primary production (brines and minerals). To meet ambitious Li recycling targets from electric vehicle (EV) Li-ion batteries (LIBs) imposed by the European Union, it is imperative to develop innovative recycling processes at an accelerated pace. Direct Lithium Extraction (DLE) methods have been developed to produce Li from brines. Herein we assess the application of various DLE technologies to extract Li from recycling streams of EV LIBs. Technical aspects and suitable initial solute concentration ranges of several DLE methods namely solvent extraction, ion-exchange resins, sorbents, membranes, and electrochemical ion pumping have been mapped. After this, an optimum pre-treatment route of the EV LIB recycling process has been chosen by estimation of Li recoveries and losses through different combinations of dry and wet crushing followed by froth flotation for anode and cathode separation. Pyrolyzing the whole cells/modules followed by dry crushing and flotation was found to be the most ideal process which can minimize Li losses during pre-treatment. Furthermore, the estimation of concentrations, compositions, and volumes of streams for the downstream hydrometallurgical process is done to identify Li-containing streams where DLE can be used, and suitable technologies have been highlighted. The incorporation of DLE has the potential to minimize Li losses in the recycling process. However, various DLE methods may be required to recover Li in different steps, with nanofiltration and reverse osmosis, selective ion-exchange resins, and solvent extraction being the most promising options.