Method and electrochemical device for low environmental impact lithium recovery from aqueous solutions

Abstract

An efficient and low environmental impact method is disclosed for the recovery of lithium from aqueous solution, for example, brines from high altitude salt lakes. The method comprises the use of an electrochemical reactor with electrodes which are highly selective for lithium, where lithium ions are inserted in the crystal structure of manganese oxide in the cathode, and extracted from the crystal structure of manganese oxide in the anode. Also disclosed are three-dimensional carbon electrodes embedded in manganese oxides formed by impregnating a porous support, for example a carbon felt, with a manganese oxide/carbon black slurry.

Description

BACKGROUND OF THE INVENTION[0001]The industrial importance of lithium either in the metallic form or as a chemical compound is rapidly increasing due to its multiple application in diverse fields such as batteries, pharmacological preparations (e.g., to treat manic depression), coolants, aluminum smelting, ceramics, enamels and glasses, nuclear fuels, or the production of electronic grade crystals of lithium niobate, tantalite and fluoride. Lithium compounds are required for the fabrication of several components in lithium-air and lithium-ion batteries for electric and hybrid electric vehicles, such as the cathode materials and electrolyte salts. Some batteries require highly pure lithium metal.[0002]In the case of lithium-ion batteries, lithium compounds can be required for the fabrication of the cathode. Lithium compounds such as lithium manganese oxide, lithium iron phosphate, or mixed metal oxides such as lithium cobalt nickel manganese oxide can be used as active materials for ...

AI Technical Summary

Benefits of technology

[0007]The present disclosure provides an efficient and low environmental impact method for the recovery of lithium from aqueous solutions, for example, brines from high altitude salt lakes. More particularly, the disclosed method comprises the use of an electrochemical device with electrodes which are highly selective for lithium. Lithium ions are inserted in the crystal structure of a battery-type lithium insertion electrode (e.g., a manganese oxide) functioning as cathode in an extraction step in which the electrolyte is a brine or other aqueous solution containing lithium. The insertion lithium is then extracted from the crystal structure of manganese oxide in an extraction or concentration step in which the battery-type lithium insertion electrode functions as the anode and the electrolyte is a diluted aqueous solution.

Problems solved by technology

The chemical process is relatively simple, however, it has a high environmental impact since it takes place in high altitude salt lakes (over 4,000 meters above sea level), were water is scarce and ecosystems are fragile.

This extraction process profoundly alters the water balance in the high altitude salt lake, introduces chemicals in the environment, and generates large volumes of chemical waste.

In seawater, lithium reserves are estimated at about 230 million tons, although lithium is present in much lower concentrations than in the brines from salt flats (0.1-0.2 ppm) and therefore it is much more expensive to extract.

Images