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 a D2EHPA extraction system, the subsequent recovery of lithium with a 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⁻¹, 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.