Effect of Na+ on Li extraction from brine using LiFePO4/FePO4 electrodes

LiFePO4/FePO4 electrodes are used to extract Li from brine. The root cause of the negative influences of Na+ on the intercalation/deintercalation of Li+ is found by means of electrochemical analysis. The side-effect of Na+ on the extraction of Li can be eliminated by controlling the electrolytic voltage to less than 0.3 V, and the electrode exhibits excellent cycle performance under this condition. When the electrolytic voltage is 0.25 V, the concentration of Li+ in solution reaches 432 mg · L− 1 after 10 electrolytic cycles, and the average Li+ capacity of the electrode reaches 38.6 mg · g− 1 LiFePO4.