An electro-metathesis membrane reactor for directly producing LiOH with purity exceeding 99.5%

Abstract

Producing battery-grade lithium hydroxide (LiOH) from lithium salts is essential for high-performance lithium-ion batteries. Traditional causticization methods, which involve metathesis reactions between lithium salts (such as Li₂CO₃, Li₂SO₄, or LiCl) and bases (such as Ca(OH)₂, NaOH, or Ba(OH)₂), often result in low concentrations of LiOH and significant lithium loss dragged by CaCO₃/Na₂SO₄/BaSO₄ as solid waste. To address these challenges, we developed the “electro-metathesis” membrane reactor, which integrates the metathesis reaction with an electro-membrane system based on ion-distillation technology. This technology enhances the causticization process by regulating ion migration through ion exchange membranes and blocking impurity ions stage by stage, improving lithium recovery to 84.4% and achieving high-purity (99.6%) LiOH products. Furthermore, the process cost is 3.32 $/kg LiOH, which is lower than traditional causticization processes. This research highlights the advantages of the “electro-metathesis” membrane reactor in process efficiency, product quality, and cost management, showing strong potential for industrial applications.