Simultaneous Production of Lithium Hydroxide and Sulfuric Acid from Lithium Sulphate by Conventional Electrodialysis

Abstract

The production of lithium hydroxide from lithium sulphate has gained increasing attention due to the growing demand associated with lithium-ion batteries, with electrodialysis emerging as an attractive alternative to conventional processing routes. In this study, the simultaneous production of lithium hydroxide and sulphuric acid from lithium sulphate monohydrate was evaluated using conventional electrodialysis with a configuration consisting of cation- and anion-exchange membranes. Nine experimental trials were conducted by varying the applied voltage (6, 10.5, and 15 V) and the initial lithium sulphate concentration (6, 9, and 12 g/L), employing a three-compartment system. The experimental results indicate that the highest concentrations of lithium hydroxide and sulphuric acid were obtained when operating the electrodialysis cell at an applied voltage of 15 V and an initial lithium sulphate concentration of 12 g/L. Under these conditions, concentrations of 0.153 mol/L of LiOH and 0.067 mol/L of H2SO4 were achieved after 240 minutes of operation. Furthermore, the results showed that the average electrical efficiency reached 75%, while the specific energy consumption was approximately 15.7 kWh/kg of LiOH produced. These findings demonstrate the feasibility of conventional electrodialysis without a bipolar membrane for the simultaneous generation of LiOH and H2SO4, offering an energetically competitive alternative for the utilisation of lithium sulphate solutions.