Efficient Preparation of Battery-Grade Li₂CO₃ from Spent Battery Leachate via Integrated Solvent Extraction and Direct Precipitation

Abstract

The preparation of battery-grade Li₂CO₃ from spent lithium-ion battery leachates requires lengthy and costly multi-stage processes, including thermal evaporation, precipitation, carbonation, and thermal decomposition, resulting in significant lithium loss, high reagent/energy consumption, and elevated production costs. This study presents a simplified and green lithium extraction process that integrates the selective removal of divalent impurities via D2EHPA extraction system, the subsequent recovery of lithium with LIX54–TBP synergistic extraction system, and the direct precipitation of battery‑grade Li₂CO₃. In the impurity-removal stage, countercurrent extraction with D2EHPA reduced total divalent impurities to below 0.5 mg/L, with lithium losses of less than 2.3%. Subsequently, LIX54–TBP synergistic extraction achieved over 99.9% lithium recovery while effectively rejecting Na⁺ and anionic impurities. After scrubbing and stripping, an ultra-pure Li₂SO₄ solution was obtained, from which battery-grade Li₂CO₃ was directly precipitated by the addition of Na₂CO₃. The proposed integrated process was systematically validated through small-scale experiments, mechanistic analysis, and continuous pilot-scale operation. It offers multiple advantages, including a simplified flowsheet, high recovery efficiency, reduced environmental impact, and straightforward scalability, positioning it as a sustainable and practical solution for lithium reclamation from spent lithium-ion battery leachates.