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.

本研究提出假设，采用乙醇强化的磷酸胆碱（phosphocholine, PCho）配位工艺，可为从废锂离子电池（LIBs）中回收钴提供一种选择性更强、效率更高的方法。由磷酸与氯化胆碱合成的磷酸胆碱具有独特的双功能特性，可实现与钴离子的选择性配位。我们推测，乙醇可通过调控溶剂化动力学、稳定钴配合物，在不显著干扰锂等其他金属离子的前提下，提升钴的萃取效率。

实验结果证实，磷酸胆碱经乙醇强化后，可从废LIBs中选择性回收钴。最优浸出工艺条件为：90℃下反应480分钟，固液（S/L）比33 g/L。在此条件下，浸出液中锂浓度为11811 mg/L，钴浓度为17798 mg/L，锂和钴的萃取率分别达99.9%和98.8%。上述高萃取率凸显了磷酸胆碱用于浸取以钴酸锂（LiCoO2）为主要成分的黑粉料中两种金属的有效性。进一步表征结果证实，可得到纯度分别为95.9%和99.7%的高纯度磷酸氢钴（CoHPO4）与磷酸锂（Li3PO4）。

该乙醇强化工艺可选择性沉淀钴，使锂留存于浸出液中，后续可通过pH调节回收锂。乙醇对溶剂化动力学的调控改变了钴配位配合物的结构，大幅降低了其他金属离子的共沉淀风险。

实验数据表明，温度、反应时间与固液比是影响金属萃取的关键因素。在较高温度（80~90℃）下，金属萃取率显著提升，其中90℃下反应480分钟时，钴的浸出率达到峰值98.8%；而较低温度下，锂与钴的萃取率均显著下降。该结果验证了本研究的假设：从废LIBs中萃取金属的效率与温度高度相关。此外，本研究发现固液比为30 g/L时，萃取效率与试剂消耗可达到最优平衡。

采用中心复合设计（Central Composite Design, CCD）的响应面法（Response Surface Methodology, RSM）分析显示，温度对锂与钴的浸出过程均存在非线性影响。温度与固液比的交互作用显著，表明较高的固液比可在高温环境下提升浸出效率。方差分析（Analysis of Variance, ANOVA）证实了钴萃取模型的稳健性，其决定系数R²高达0.9606；锂萃取模型的拟合度稍低（R²=0.8336），但仍保持较高效率，这暗示浸出过程可能存在未被考量的变量影响，例如回收阶段的pH调节作用。