While most electronics, including autonomous vehicles, power themselves with batteries made of lithium, the growing demand for this element is expected to exhaust our planet’s land-based reserves by 2080. Future shortages could cause battery prices to skyrocket and hinder the growth of electric vehicles and other lithium-dependent technologies such as batteries used to store renewable energy. Until we find viable alternatives that can replace lithium to power our tech, seawater may offer an opportunity to mitigate the risk associated with the element’s scarcity.
While previous efforts to extract lithium from seawater have proved to be inefficient, KAUST scientists have developed an economically viable system that can extract high-purity lithium from our oceans, potentially reducing our dependency on land-based resources.
As reported by EurekAlert!, the new process uses an electrochemical cell containing a ceramic membrane made from lithium lanthanum titanium oxide (LLTO). The membrane’s crystal structure contains holes just wide enough to let lithium ions pass through while blocking larger metal ions. The system is also made of different compartments, featuring a copper cathode and a platinum-ruthenium anode.
The researchers tested the system using seawater from the Red Sea. At a voltage of 3.25V, the cell generates hydrogen gas at the cathode and chlorine gas at the anode. This drives the transport of lithium through the LLTO membrane and into a chamber designed to hold the lithium-rich water that, reaching concentrations of more than 9,000 ppm.
To make the final product pure enough to meet battery manufacturers’ requirements, the scientists then adjusted the pH of the solution to deliver solid lithium phosphate that contains mere traces of other metal ions.
The researchers estimate that the cell would need only US$5 of electricity to extract 1 kilogram of lithium from seawater. “We will continue optimizing the membrane structure and cell design to improve the process efficiency,” says group leader Zhiping Lai, whose team hopes to collaborate with the glass industry to produce the LLTO membrane at a large scale and affordable cost.
