An electro‐metathesis membrane reactor for directly producing <scp>LiOH</scp> 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 Li 2 CO 3 , Li 2 SO 4 , 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 CaCO 3 /Na 2 SO 4 /BaSO 4 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.