Adaptive Mg²⁺-Gating Membranes for Battery-Grade Lithium Extraction

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Conventional nanofiltration membranes struggle with lithium extraction from salt lakes due to fixed nanochannel sizes and variable Mg²⁺/Li⁺ ratios.
• Efficient separation of lithium from magnesium is crucial for battery-grade lithium production.

Purpose of the Study:

• To develop adaptive Mg²⁺-gating membranes for enhanced lithium extraction from salt lake brines.
• To address the limitations of conventional membranes in handling fluctuating Mg²⁺/Li⁺ ratios.

Main Methods:

• Grafting 4'-Aminobenzo 15-crown-5-ether (AB-15C5) onto polyamide (PA) membranes to create PA-15C5 membranes.
• Utilizing molecular weight cutoff (MWCO) testing and Zeta potential analyses for experimental validation.
• Employing density functional theory (DFT) and molecular dynamics (MD) simulations for theoretical validation.

Main Results:

• Demonstrated adaptive Mg²⁺-gating effect enabling responsive nanochannel dimensional switching.
• Achieved a high Li⁺/Mg²⁺ separation factor of 214.9 at a low Mg²⁺/Li⁺ molar ratio of 0.01.
• Successfully reduced Mg²⁺/Li⁺ ratio to 4.0 * 10^{- 4} and extracted battery-grade lithium with 99.97% purity in a three-stage process.

Conclusions:

• The developed PA-15C5 membranes offer a novel paradigm for lithium extraction from salt lakes.
• Adaptive gating membranes effectively convert Mg²⁺ competition into a separation advantage.
• This technology surpasses existing methods, enabling efficient and high-purity lithium recovery.