Redox Flow Battery for Continuous and Energy-Effective Lithium Recovery from Aqueous Solution

Abstract

Lithium-ion batteries are the primary power source for electric vehicles and portable electronic devices, creating a massive demand to mine and extract lithium. So far, lithium extraction has focused on brine and geological deposits. Yet, access to the enormous amount of lithium (at low concentration) in the earth’s oceans and other aqueous media remains challenging. Electrodialysis with Li-selective ceramic membranes could effectively separate lithium from seawater but at a high energy cost. Reversible electrochemical processes, like redox flow batteries, can overcome the limitation of electrodialysis-based systems. Herein we propose a system combining Li-selective ceramic membranes and a simple redox flow electrolyte to accomplish continuous lithium recovery from seawater. The lithium-extraction redox flow battery (LE-RFB) extracts dissolved lithium with a purity of 93.5% from simulated seawater, corresponding to a high Li/Mg selectivity factor of about 500.000:1. Benefiting from a low operating voltage, 1 g of lithium is extracted with only 2.5 Wh of energy consumption.