Ion trap membrane with confined bind-jump strategy for high-efficiency direct lithium extraction

Area of Science:

• Materials Science
• Chemical Engineering
• Electrochemistry

Background:

• Growing demand for lithium in energy storage technologies necessitates improved extraction methods.
• Traditional salt-pond lithium extraction processes result in significant lithium losses (>50%).
• Separating lithium ions from sodium and potassium ions is challenging due to similar ionic properties.

Purpose of the Study:

• To develop an efficient method for lithium extraction from salt lakes.
• To overcome the challenge of separating lithium ions from other alkali metal ions.

Main Methods:

• Developed a covalent organic framework-based ion trap membrane embedded with lithiophilic diketone molecules (2-thenoyltrifluoroacetone, HTTA).
• Utilized a "bind-jump" transport mechanism where HTTA sites selectively bind and facilitate lithium ion transport.
• Optimized membrane composition (HTTA1-1,3,5-triformylphloroglucinol-tris(4-aminophenyl)amine/polyacrylonitrile) for enhanced performance.

Main Results:

• The optimized membrane achieved high lithium ion/sodium ion selectivity (>320).
• Demonstrated high lithium ion permeance (~143 mmol/m²/h) under electrodialysis.
• The membrane exhibited stable performance over 10 cycles, indicating durability.

Conclusions:

• The developed covalent organic framework-based ion trap membrane offers a scalable strategy for efficient lithium extraction.
• The "bind-jump" mechanism effectively modulates thermodynamic and kinetic factors for selective lithium ion capture.
• This technology shows promise for improving lithium recovery from complex brines, supporting energy storage needs.