Abstract

The growing demand for lithium-ion batteries has intensified the need for efficient processes to produce lithium hydroxide (LiOH), a compound with superior performance in cathode manufacturing compared to lithium carbonate. Conventional LiOH production from brine involves the lime conversion of lithium carbonate, which increases costs and process complexity. In this study, Donnan dialysis using an anion exchange membrane (AEM) was evaluated as a direct route for LiOH production from lithium chloride (LiCl) brines. Laboratory-scale experiments assessed the effect of operating conditions on chloride (Cl−) removal efficiency and hydroxide transfer, including LiCl concentration, NaOH concentration, temperature, and tank volume ratio. Results showed near 99.9% Cl− transfer within 4 h for low-concentration LiCl solutions (0.11% w/w Li+), with minimal Na+ leakage from the draw solution (1.94% Na+). At high NaOH concentrations (6.3% w/w NaOH) and large volume ratios (1:4.9), residual Cl− contents as low as 2.3–4.9% were achieved after 24 h. Membrane ion exchange capacity was preserved under draw-side operation at 40 °C. A phenomenological transport model, calibrated with experimental data (RMSE 2.9%) and validated with independent tests (<5.2% error), accurately described ion migration and identified NaOH concentration, LiCl concentration, and volume ratio as the most influential parameters. Optimization predicted an average Cl− flux of 0.0041 kg/m2h, with leakage of 1.7% Li+ and 3.8% Na+, achieving 91% transfer in ∼600 min versus 1500 min experimentally. These results demonstrate the potential of Donnan dialysis as a low-energy downstream conversion step for transforming LiCl streams obtained from prior extraction and purification into LiOH.