Increasing demand for lithium has been largely spurred by the rapid growth of lithium-ion batteries, most notably in electric vehicles. The need for lithium will continue to increase as demand for safe, reliable, and sustainable energy grows. Global lithium production more than tripled between 1995 and 2008 to nearly 140,000 tons, and lithium demand is projected to reach as high as 1.6 million tons by 2030 with the rise of electric vehicles. Unfortunately, the global land-based lithium supply is maldistributed. A scalable electrochemical route to lithium extraction from brines and seawater is investigated. The oceans represent a nearly infinite lithium supply, containing approximately 230 billion tons of lithium compared to just 14 million tons on land, albeit at very low concentrations of approximately 0.17 ppm.

A four-step electrochemical lithium extraction method is presented. The working lithium iron phosphate (LFP) electrode is first inserted into the lithium-containing brine or seawater, and a negative current is applied to the system. During discharge, lithium ions intercalate into the working electrode. Next, the electrode is placed in a recovery solution, and the system is charged to release the lithium on the electrode surface. The lithium-free working electrode is then reused in another cycle. Once a substantial lithium concentration is achieved in the recovery solution following several cycles, soda ash is added to precipitate the lithium ions as lithium carbonate, the working form of lithium in many battery applications. The working electrode is surface treated with a lithium-selective polymer (LSP) coating to exclude larger, more concentrated metal ions such as sodium from intercalating to the electrode surface. This work explores the effectiveness of crown ethers such as Dibenzyl-14-crown-4 as LSPs.

The combination of our electrochemical extraction process and a focus on enhancing selectivity shortens the lithium production time from years to days and presents a promising image for the future of lithium mining. The ability to extract lithium from the oceans with nominal energy requirements and environmental impacts could revolutionize the lithium mining and battery industries.