Three-chamber electrochemical reactor for selective lithium extraction from brine

Area of Science:

• Materials Science
• Electrochemistry
• Geochemistry

Background:

• Efficient lithium recovery from geothermal brines is critical for the burgeoning battery industry.
• Existing electrochemical methods face challenges in selectively separating lithium ions (Li+) from coexisting cations like Na+, K+, Mg2+, and Ca2+ due to their similar ionic properties.
• Side reactions, such as chlorine evolution, can reduce the efficiency of lithium extraction processes.

Purpose of the Study:

• To develop and evaluate a novel three-chamber electrochemical reactor for efficient lithium recovery from complex brines.
• To enhance the transference number of lithium ions (tLi+) and minimize side reactions.
• To investigate the cation transport mechanism at the electrolyte interface for optimized lithium separation.

Main Methods:

• Design and implementation of a three-chamber reactor with a central polymer porous solid electrolyte.
• Utilizing a lithium-ion conductive glass ceramic (LICGC) membrane for selective ion transport.
• Conducting electrochemical experiments to measure transference numbers and Faradaic efficiency for chlorine evolution.
• Performing surface analysis to elucidate cation transport mechanisms.

Main Results:

• The three-chamber reactor design improved the lithium transference number (tLi+) by 2.1 times compared to a two-chamber system.
• Chlorine evolution side reaction was reduced to 6.4% Faradaic Efficiency.
• The LICGC membrane enabled a high tLi+ of 97.5% in LiOH production from simulated brine.
• Concentrations of Na+, K+, Mg2+, and Ca2+ were reduced below detection limits.

Conclusions:

• The developed three-chamber reactor with a polymer solid electrolyte and LICGC membrane offers a highly efficient method for selective lithium recovery from geothermal brines.
• This approach effectively addresses the challenge of separating Li+ from interfering cations and suppresses undesirable side reactions.
• Understanding the cation transport mechanism, particularly the influence of Na+ on Li+ migration, is key to further optimizing lithium extraction technologies.