Three-chamber electrochemical reactor for selective lithium extraction from brine.

Abstract

Efficient lithium recovery from geothermal brines is crucial for the battery industry. Current electrochemical separation methods struggle with the simultaneous presence of Na⁺, K⁺, Mg²⁺, and Ca²⁺ because these cations are similar to Li⁺, making it challenging to separate effectively. We address these challenges with a three-chamber reactor featuring a polymer porous solid electrolyte in the middle layer. This design improves the transference number of Li⁺ (t_<i>Li</i>+) by 2.1 times compared to the two-chamber reactor and also reduces the chlorine evolution reaction, a common side reaction in electrochemical lithium extraction, to only 6.4% in Faradaic Efficiency. Employing a lithium-ion conductive glass ceramic (LICGC) membrane, the reactor achieved high t_<i>Li</i>+ of 97.5% in LiOH production from simulated brine, while the concentrations of Na⁺ K⁺, Mg²⁺, and Ca²⁺ are below the detection limit. Electrochemical experiments and surface analysis elucidated the cation transport mechanism, highlighting the impact of Na⁺ on Li⁺ migration at the LICGC interface.