Ethanol-enhanced phosphocholine leaching experiment from LCO cathode material: Raw data(2024-2025)

This study hypothesized that an ethanol-enhanced phosphocholine (PCho) coordination process could offer a more selective and efficient method for cobalt recovery from spent lithium-ion batteries (LIBs). Phosphocholine, synthesized from phosphoric acid and choline chloride, has unique bifunctional properties that enable selective coordination with cobalt ions. We posited that ethanol would enhance this process by affecting the solvation dynamics, stabilizing cobalt complexes, and increasing the efficiency of cobalt extraction without significant interference from other metal ions like lithium.
The results confirm that phosphocholine, particularly when enhanced by ethanol, can selectively recover cobalt from spent LIBs. The optimal leaching conditions were found to be 90°C for 480 minutes with an S/L ratio of 33 g/L. Under these conditions, the leach liquor contained 11,811 mg/L of lithium and 17,798 mg/L of cobalt, achieving extraction efficiencies of 99.9% for lithium and 98.8% for cobalt. These high extraction rates highlight the effectiveness of phosphocholine for leaching both metals from the black mass, primarily composed of lithium cobalt oxide (LiCoO2). Further characterization confirmed the formation of high-purity cobalt hydrogen phosphate (CoHPO4) and lithium phosphate (Li3PO4), with purities of 95.9% and 99.7%, respectively.
The ethanol-enhanced process selectively precipitated cobalt while leaving lithium in the leachate, which was recovered through pH adjustment. Ethanol's role in solvation dynamics altered cobalt coordination complexes, minimizing co-precipitation of other metal ions.
The data indicates that temperature, time, and the solid-liquid ratio are key factors influencing metal extraction. At higher temperatures (80–90°C), the extraction rates were significantly improved, with cobalt leaching peaking at 98.8% after 480 minutes at 90°C. In contrast, at lower temperatures, both cobalt and lithium extraction were significantly reduced. This finding supports the hypothesis that the efficiency of metal extraction from spent LIBs is highly temperature-dependent. Moreover, the study revealed that an S/L ratio of 30 g/L provided the best balance between extraction efficiency and reagent consumption.
The application of RSM with a central composite design (CCD) revealed that temperature had a nonlinear impact on both lithium and cobalt leaching. The interaction between temperature and solid-liquid ratio was significant, indicating that a high S/L ratio enhances the leaching efficiency at higher temperatures. Statistical analysis using analysis of variance (ANOVA) confirmed the robustness of the model for cobalt extraction, with a high R² value of 0.9606. Lithium extraction, although still efficient, showed a slightly lower fit (R² = 0.8336), suggesting potential variability in the leaching process that may be influenced by unaccounted-for factors such as the role of pH adjustments during the recovery phase.