Selective Electrochemical Capture and Release of Lithium from Seawater

Background

Lithium (Li) is a valuable element that is experiencing skyrocketing demand due to the growth of Li-ion batteries for energy storage applications. Current Li extraction relies on the lime-soda solar evaporation technique from Li-rich brines. However, this process is very slow, requiring 1-2 years, and current techniques are not expected to keep up with projected market demands. Seawater, which contains vast quantities of dissolved Li+, represents an underutilized source. It is estimated that seawater contains about 10,000 more dissolved Li than all terrestrial and freshwater reserves. While many sorbent-based membrane technologies are being explored for the selective capture of Li+ from seawater or from salty brine well waters, these methods typically rely on further treatment of the membranes with strong acids to remove the extracted Li+. There is a need for techniques that extract Li+ from seawater without requiring expensive membranes or acidic workups and that do not have the related environmental impacts.

Description

Researchers at the University of California, Santa Barbara have formulated a novel electrochemical process for extracting Li+ from seawater. This new method utilizes redox-switchable lithium-selective macrocyclic donors (i.e. carboranes or Cb) to selectively capture and release Li+ from seawater under flow conditions. This technique anchors chelating Cb compounds directly to electrode surfaces, enabling lithium capture from seawater flowing across the electrode. The Li+ is subsequently released from the electrode via application of a low electric current to generate a concentrated Li+ solution. This technique offers cost savings by avoiding membranes and acidic treatments and minimizes environmental impacts by eliminating reagent waste, providing an innovative solution for the growing lithium demand.

 Additional information: https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/chem.202502902 

Advantages

• Efficient lithium capture from seawater requiring only a small electric current
• Avoids costly membranes and acid-based workups
• Minimizes chemical waste and environmental footprint

Applications

• Lithium capture and extraction for battery manufacturing and energy storage markets
• Sustainable resource development

Patent Status