(380af) Selective Extraction of Lithium from Brines Via Chemical Reduction of Intercalation Materials

Worldwide demand for lithium (Li) is increasing due to production of Li-ion batteries for increasing numbers of electric vehicles and stationary energy storage systems. Li-ion batteries have a diversity of materials used in the cathode, anode, and electrolyte; however, Li is required for all of these batteries. Worldwide production of Li increased more than 20,000 metric tons (and by more than 25%) between 2020 and 2021, and Li-ion batteries were the end use for 80% of the Li. New Li production sources and technologies are needed both to more sustainably support Li production and to prevent supply shortages. Supply limitations can result in Li price fluctuations which negatively impact the cost and adoption of energy storage technologies such as electric vehicles. Increasing electric vehicle proliferation will require keeping Li-ion battery costs manageable, which means that broader decarbonization of the energy sector is reliant on Li resource supply being reliable and achieving significant growth. The system that will be described in this talk is targeted towards extraction of Li from a less conventional geothermal brine resource.

More conventional Li resources are extracted from either ores or brines and have impacts with regards to chemical and energy inputs. This presentation will describe initial efforts in the use of an extraction process based on the use of chemical redox to selectively drive Li from brine into a solid intercalation material. The brine source was intended to simulate a geothermal fluid resource, more specifically the discharge brine at the Salton Sea. To provide the driving force to reduce the solid material, soluble additives were incorporated into the brine solution to provide the necessary shift in redox potential of the brine solution. While other brine components were also included, the primary focus was separation of Li from sodium (Na), because the target component was Li and the largest concentration element in the brine was Na; the molar ratio of Li:Na was 1:78. The driving force for extraction of Li into the solid phase was chemical redox facilitated by the solution phase composition – there were no additional energy inputs during Li uptake. Li adsorption capacity as a result of extraction in some cases approached 4 mmol Li per g solid, and the selectivity factors for Li to Na for the two systems were exceeded 300 for the highest selectivity experiments. This work more broadly provided insight into enhancing Li capture selectivity through modification of redox solution compositions when capturing Li from brine using intercalation materials.