Efficient lithium extraction method could transform battery supply chains

In the race for the growing worldwide demand for lithium – a critical component in batteries for electric vehicles – a team of researchers from the Elimelech Labor at Rice University developed a breakthrough lithium extraction method that could turn the industry.

Published in her study in Science progressThe researchers showed almost perfect lithium selectivity by repeating solid-state electrolytes (SSES) as membrane material for aqueous lithium extraction. While they were originally designed for the fast line of lithium ions in solid-state batteries, as there are no other ions or liquid solvents-it was found that the strongly ordered and limited structure of SSES enables an unprecedented separation of ions and water in aqueous mixtures.

This discovery creates a possible breakthrough in sustainable resource recovery, which reduces the dependencies on conventional mining and extraction techniques, which are both time-consuming and environmental compatibility.

“The challenge is not only to increase lithium production, but also in a way that is both sustainable and economically viable,” said the corresponding author Menachem Elimelech, the professor of civil and environmental engineering from Nancy and Clint Carlson.

In order to make the lithium extraction more environmentally friendly, the researchers examine direct lithium extraction technologies that recover lithium from unconventional sources such as oil and gas-produced water, industrial waste water and geothermar brine. However, these methods have to struggle with ionenselectivity, especially if they try to separate lithium from other ions with similar size or load as magnesium and sodium.

The new approach developed by Elimelech and his team depends on a fundamental difference between SSES and conventional nanoporous membranes. While traditional membranes are dependent on hydrated nanoscala pores on the transports, shuttle lithium ions through an anhydrous hop mechanism within a heavily ordered crystalline grille.

“This means that lithium ions can migrate by the membrane, while other competing ions and even water are effectively blocked,” said the first author Sohum Patel, who is now postdoctoral at the Massachusetts Institute of Technology. “The extreme selectivity that our SSE-based approach offers makes it a highly efficient method for the lithium harvest, since energy is only selected to move the desired lithium ions over the membrane.”

The research team, which also includes Arpita Iddya, Weiyi Pan and Jianhao Qian -Postdoctoral researcher in ELIMELEBCHABOR in Rice, tested this phenomenon using an electrodialysis setup, in which an applied electrical field drove lithium ions via the membrane. The results were striking: Even with high concurring ions, the SSE showed the close perfect lithium selectivity consistently without detectable competing ions in the product current etwas could not achieve conventional membrane technologies.

Using a combination of arithmetic and experimental techniques, the team examined why the SSEs showed such remarkable lithium-ion selectivity. The results showed that the rigid and densely packed crystalline grille of the SSE water molecules and larger ions such as sodium prevented the membrane structure. Magnesium ions that have a different load than lithium ions were also not compatible with the crystal structure and thus rejected.

“The grille acts as a molecular sieve and only makes it possible to go through lithium ions,” said Elimelech. “This combination of very precise size and load exclusion makes the SSE membrane so unique.”

The researchers found that competing ions did not penetrate the SSE that their presence in the feed solution reduced the lithium flow by blocking available surface locations for ion exchange.

With lithium deficiency on the horizon, the industries that depend on lithium-ion batteries, including sectors for automobiles, electronics and renewable energies, are looking for additional lithium sources and more sustainable extraction methods. SSE-based membranes could play a crucial role in securing a stable lithium supply without the environmental impact of traditional mining.

“By integrating SSEs into electrodialysis systems, we can enable direct lithium extraction from a series of aqueous sources, which reduces the need for great evaporation ponds and chemical-intensive cleaning steps,” said Patel. “This could significantly reduce the ecological footprint of lithium production and at the same time make the process more efficient.”

The results also indicate broader applications that go beyond lithium for SSEs in ionelective separations.

“The mechanisms of ionenselectivity in SSES could inspire the development of similar membranes to extract other critical elements from water sources,” said Elimelech. “This could open the door for a new class of membrane materials to restore resources.”