Department of Chemical Engineering, National Taiwan University of Science and Technology, 43 Keelung Road, Section 4, Taipei 106, Taiwan.
Molecules. 2020 May 6;25(9):2166. doi: 10.3390/molecules25092166.
The leaching of valuable metals (Co, Li, and Mn) from spent lithium-ion batteries (LIBs) was studied using subcritical water extraction (SWE). Two types of leaching agents, hydrochloric acid (HCl) and ascorbic acid, were used, and the effects of acid concentration and temperature were investigated. Leaching efficiency of metals increased with increasing acid concentration and temperature. Ascorbic acid performed better than HCl, which was attributed to ascorbic acid's dual functions as an acidic leaching agent and a reducing agent that facilitates leaching reactions, while HCl mainly provides acidity. The chemical analysis of leaching residue by X-ray photoelectron spectroscopy (XPS) revealed that Co(III) oxide could be totally leached out in ascorbic acid but not in HCl. More than 95% of Co, Li, and Mn were leached out from spent LIBs' cathode powder by SWE using 0.2 M of ascorbic acid within 30 min at 100 °C, initial pressure of 10 bar, and solid-to-liquid ratio of 10 g/L. The application of SWE with a mild concentration of ascorbic acid at 100 °C could be an alternative process for the recovery of valuable metal in spent LIBs. The process has the advantages of rapid reaction rate and energy efficiency that may benefit development of a circular economy.
使用亚临界水萃取（SWE）研究了从废旧锂离子电池（LIB）中浸出有价金属（Co、Li 和 Mn）。使用了两种浸出剂，盐酸（HCl）和抗坏血酸，并研究了酸浓度和温度的影响。金属的浸出效率随酸浓度和温度的升高而增加。抗坏血酸的性能优于 HCl，这归因于抗坏血酸同时作为酸性浸出剂和还原剂的双重作用，促进浸出反应，而 HCl 主要提供酸度。通过 X 射线光电子能谱（XPS）对浸出残渣的化学分析表明，Co（III）氧化物可以在抗坏血酸中完全浸出，但不能在 HCl 中浸出。使用 0.2 M 的抗坏血酸，在 100°C、初始压力为 10 巴和固液比为 10 g/L 的条件下，通过 SWE 可在 30 分钟内从废旧 LIB 阴极粉末中浸出超过 95%的 Co、Li 和 Mn。在 100°C 下使用温和浓度的抗坏血酸的 SWE 工艺可能是从废旧 LIB 中回收有价金属的替代工艺。该工艺具有快速的反应速率和节能的优点，这可能有利于发展循环经济。
