The aim of this study was to explore the lithium carbonate precipitation from a lithium-ion battery leachate in a batch reactor by a gas–liquid and liquid–liquid reactive process, employing carbon dioxide and sodium carbonate, respectively. The effect of operating parameters including reaction time and initial reactant concentration was investigated. The obtained crystals were observed using scanning electron microscope, the crystal size distribution was studied by laser diffraction, and the crystal structures were analyzed by X-ray diffraction. Additionally, lithium content was evaluated by inductively coupled plasma spectroscopy. In the case of the liquid–liquid precipitation, scanning electron images showed that lower initial concentrations of lithium led to the formation of larger crystals, while higher concentrations yielded smaller particles with significant agglomeration. The results also indicated a higher yield for the liquid–liquid compared to gas–liquid precipitation, which could be attributed to the reaction parameters such as temperature and pH. The reduced solubility of CO2 in water at elevated temperatures, coupled with the pH decrease during the process, likely contributed to this disparity. Nevertheless, the use of carbon dioxide is of great interest since it is a greener and cost-effective approach in the lithium carbonate precipitation process. These experiments highlight the crucial role of the operating parameters in the lithium carbonate crystals.