Lithium Extraction from Seawater through Pulsed Electrochemical Intercalation

Summary

It is highly attractive to develop efficient methods to directly extract Li from seawater to secure the supply of Li. However, high concentration of Na in the seawater poses a great challenge in Li extraction. Here, we developed pulsed-rest and pulse-rest-reverse pulse-rest electrochemical intercalation methods with TiO₂-coated FePO₄ electrodes for Li extraction. The method can lower the intercalation overpotential and successfully boost the Li selectivity. Moreover, the pulse-rest-reverse pulse-rest method can also promote electrode crystal structure stability during the co-intercalation of Li and Na and prolong the lifetime of the electrode. We demonstrated 10 cycles of successful and stable Li extraction with 1:1 of Li to Na recovery from authentic seawater, which is equivalent to the selectivity of ∼1.8 × 10⁴. Also, with lake water of higher initial Li/Na ratio of 1.6 × 10⁻³, we achieved Li extraction with more than 50:1 of Li to Na recovery.