Virtually all of the lithium required to manufacture batteries for portable electronics, electric vehicles and other applications in the U.S. is imported. In pursuit of a secure domestic source of the metal, researchers at U.S. Oak Ridge National Laboratory (ORNL) are developing a process for extracting lithium salts from the concentrated brine byproduct available at geothermal power plants.

There are currently 13 geothermal facilities in California’s Salton Sea region, with each a possible source of The sorbent targets lithium recovery from geothermal brines. Source: ORNL15,000 metric tons/year of lithium carbonate. A lithium-aluminum-layered double hydroxide chloride (LDH) sorbent is being formulated to harness this lithium resource.

The researchers synthesized LDH samples from alumina and gibbsite and studied the structures using neutron vibrational spectroscopy. Differences in the ordering of interlayer water molecules were observed, and a higher interlayer ordering of water was demonstrated to be directly linked to the stability of gibbsite- and alumina-derived sorbents. Substituting iron for aluminum improves thermodynamic stability of the sorbent material, and synthesized samples were shown to recover more than 91% of lithium from a simulated brine in laboratory tests.

In collaboration with industry partner All American Lithium, the researchers plan additional testing under simulated industrial-scale conditions, and to increase process efficiency with a membrane designed to concentrate the brines prior to LDH sorbent exposure.