Due to growing demand for lithium-based batteries for mobile phones and cars, alternative methods are being sought after to access this material.
Conventional lithium extraction from brines takes months and uses many resources like water, generating greenhouse gases.
Also read: Princeton startup recycles rare minerals from lithium batteries
Development of Membrane Technology for Lithium Extraction
The team, which comprises Dr. Qilei Song and his team in the Department of Chemical Engineering, have developed a membrane that separates lithium from saltwater by filtering it through tiny pores.
The shortcoming with this approach is that the pores also let through magnesium and other contaminants, but the team has developed a class of special polymers that are highly selective for lithium.
Selective Polymers Enhance Lithium Purification Process
The micropores provide ordered channels through which small molecules and ions can travel.
Used in an electrodialysis device, the lithium extraction process effectively pulls lithium ions through the membrane micropores by an electrical current, while larger magnesium ions are left behind.
High Purity Lithium Carbonate Produced from Salt-lake Brines
Tested on simulated salt-lake brines, these PIM membranes were highly selective for lithium and produced high purity battery-grade lithium carbonate. “The polymer synthesis routes are based on commercially available monomers and simple chemical modifications, which makes scaling up the membranes relatively easy,” said Dingchang Yang, a PhD student in Dr. Song’s group who led the experimental work.
Scalable Lithium Extraction Technology for Various Applications
They can also be incorporated easily into commercial membrane modules and combined with other separation processes, which will also speed their use.
The team believes the technology can be used in areas such as energy storage and water purification.
