LiMn2O4||Li1– x Mn2O4 Symmetric Electrochemically Switched Ion Exchange (s-ESIX) System for Li+ Extraction from Lithium Precipitation Mother Liquor

Abstract

Recovery of residual lithium from lithium precipitation mother liquor is crucial for enhancing lithium utilization efficiency. However, the high Na+ concentration in the mother liquor results in severe ion interference, cross-contamination, and low overall lithium recovery. Herein, a symmetric electrochemically switched ion exchange (s-ESIX) system with a LiMn2O4||Li1–xMn2O4 configuration and a buffer chamber equipped with two anion exchange membranes was developed for continuous lithium extraction with suppressed Na+ leakage. To maximize lithium recovery, an integrated process comprising air purging/washing, buffer-chamber isolation, and two-stage recovery was implemented. In this system, lithium recovery from actual mother liquor reached 87.67%, with a Li/Na separation factor of 171.09. High-purity (99.83%) Li2CO3 was obtained from the recovered solution, achieving an overall lithium recovery of 80.10%. Therefore, this work offers a feasible approach for lithium recovery from high-salinity mother liquor, demonstrating potential for continuous operation and further process optimization.