Electrochemical lithium extraction from high Na/Li brine using LiMn2O4-Zn mixed-ion battery

The extraction of lithium from high Na/Li ratio salt lakes brine remains challenging due to the similar physicochemical properties of Li⁺ and Na⁺. In this work, a LiMn 2 O 4 (LMO)-Zn mixed-ion battery system was constructed for electrochemical lithium extraction from high Na/Li brine. The electrochemical behavior and lithium extraction performance of the system under different Na⁺ concentrations, temperatures, and current densities were systematically investigated. The results demonstrated that the LMO-Zn system maintained stable electrochemical performance in 0.1 M LiCl + 4.0 M NaCl electrolyte. At discharge rates from 0.1 C to 0.75 C, the discharge potential only slightly decreased from 2.03 V to 1.94 V, indicating favorable rate capability and electrode stability. The titanium felt current collector exhibited an initial discharge capacity of 124.3 mAh g⁻¹ and a charge capacity of 139.5 mAh g⁻¹ . ICP analysis revealed that the Li⁺ concentration in the ZnCl 2 solution increased from 0 to 2.75 mg L⁻¹ after electrochemical cycling, while the Li⁺ concentration in the Li/Na mixed solution decreased from 10 to 6.87 mg L⁻¹ , confirming effective lithium extraction and enrichment behavior. Furthermore, XRD, XPS, SEM, and GITT analyses demonstrated the good reversibility and structural stability of the LMO electrode during cycling. This work provides a promising strategy for lithium extraction from high Na/Li ratio salt lakes brine.