Ocean Mining: A Fluidic Electrochemical Route for Lithium Extraction from Seawater

Mining lithium from the ocean has long been impeded by the lack of suitable lithium extracting technology. So far, adsorption and electrochemical strategies have been investigated. However, application of the adsorption method was limited by low adsorption rate and dissolution of adsorbent. In addition, experiments using the electrochemical method were either confined to lithium-enriched brine or performed in static electrochemical cell, which requires replacement of electrode. Herein, we report a fluidic electrochemical extraction (FEE) route for lithium extraction from seawater. This FEE system consists of an oxygen evolution cathode, a MnO2 working electrode, and an oxygen reduction anode. In operation, a voltage was applied on the cells to force Li+ to enter into MnO2 and release it as LiOH raw material. By virtue of the flow architecture, we have successfully extracted lithium from seawater with 7.0 ppm Li+. The highest absorption capacity reaches up to 20.6 mg Li+ per 1.0 g MnO2 for 0.8 h, corresponding to an electrical energy consumption of 7.2 Wh for extracting 1.0 g Li+. The fluidic electrochemical strategy developed in this study provides a remarkably effective method for lithium extraction from seawater and can be extended to extract other metal ions from the ocean or even in other fluids.