Ladder electrodialysis: Efficient up-concentration of lithium ion and its mechanisms behind

The development of lithium extraction technology from salt lakes has seen significant demand in recent years, driven by the surge in energy storage needs for lithium-ion batteries used in electric vehicles and renewable power plants. Currently, evaporation technologies such as Mechanical Vapor Recompression (MVR) and Multi-Effect Distillation (MED) are commonly employed to concentrate lithium chloride for subsequent lithium carbonate precipitation. However, these evaporation methods limit lithium yield and increase capital and operational costs, particularly in high latitude areas. Pressure-driven membrane processes like reverse osmosis are hindered by concentration polarization and cannot significantly increase lithium chloride concentration. This study proposes a new membrane stack configuration with a laddered compartment design, termed Ladder Electrodialysis (LED), which addresses the concentration polarization issue and achieves a lithium salt (LiCl) concentration of 16.39 % (196 g·L⁻¹). Economic analysis shows that the energy consumption is only 0.42 kWh per kilogram of LiCl. Ladder electrodialysis is a novel salt concentration technology, with applications in brine valorization or disposal.