Electrochemical flow reactor for selective extraction of lithium chloride from natural brines

Abstract

An electrochemical flow reactor for the extraction of lithium chloride from natural brines has been designed and tested. It comprises two 3D porous packed bed electrodes and an anion exchange membrane. The electrodes were filled with conducting petroleum coke particles covered with LiMn2O4 (anode) in contact with dilute LiCl recovery solution and partly de-lithiated Li1-xMn2O4 (cathode) in contact with natural brine. The electrolytes were circulated at constant flow rate through the porous packed bed electrodes and a constant current was passed at the lithium deficient Li1-xMn2O4 (cathode) with Li+ ion intercalation and de-intercalation at the LiMn2O4 (anode), while a flow of chloride ions operated at the anion selective membrane to compensate charge. In a second step, the electrolytes were exchanged and LiCl was recovered from the lithiated Li1-xMn2O4, now acting as anode. A mathematical model for the flow reactor with the diffusion and migration described by the Nernst-Planck equation, the convective flow of electrolyte and the LiMn2O4 battery intercalation model has been developed using the finite element method under the COMSOL environment.