Abstract: The variations of cathode liquid pH and temperature and the phase composition and microstructure of Li₂CO₃ products were studied during the electrolytic process when the anolyte concentration was 300g/L and catholyte concentration were 50， 100， 200， 300 and 400g/L， respectively. The results show that the concentration or concentration difference has little effect on the reaction mechanism in the electrolysis process， while the concentration difference has a great influence on the speed and the limit of the reaction. The amount of Li₂CO₃ products and current efficiency increase with the decrease of the concentration difference or concentration of catholyte. The crystallography of Li₂CO₃ produced from electrolysis is monoclinic. Moreover， the concentration difference not only increases the crystallization degree of Li₂CO₃ products but also refines the grains. The optimal catholyte concentration of LiCl as the electrolytic parameter is 100g/L， ie， the concentration difference between anode and cathode liquid is 200g/L.

Key words: lithium chloride, electrolysis, lithium carbonate, concentration difference, ion-exchange membrane