An electrically switched ion exchange system with self-electrical-energy recuperation for efficient and selective LiCl separation from brine lakes

Various electrochemical separation methods have been investigated for the recovery of lithium to satisfy the global demand for lithium. However, most of them are still greatly limited by high energy consumption and deficient selectivity. To overcome these issues, in this study, an electrically switched ion exchange (ESIX) system for efficient and selective LiCl separation from brine lakes was developed based on a strategy of self-electrical-energy recuperation, in which the electric energy generated in the process of LiCl uptake was proposed to compensate the energy consumed for the desorption of ions as well as the regeneration of electrodes. λ-MnO2 film coated electrode and BiOCl@PPy film coated electrode were fabricated to capture Li+ and Cl- ions in the brine lake, respectively. In the ion uptake process, the inherent potential difference between the two electrodes was balanced due to the embeddedness of Li+ and Cl- ions, which simultaneously triggered the generation of electric energy. This generated electric energy was automatically stored and provided for the desorption of the Li+ and Cl- ions from the electrodes in the ion releasing process. As a result, this ESIX system featured with extremely low energy consumption (1.007 Wh for separating per mole of LiCl) and excellent selectivity with a LiCl recovery capacity of 10.88 mg/g. It is expected that such an ESIX system with self-electrical-energy recuperation could be a promising alternative to those current electrochemical techniques for the recovery of LiCl from brine lakes.