Separation of Co and Li from spent lithium-ion battery leachate using a synergistic extraction system based on Cyanex 272 and Cyphos IL 101

Spent lithium-ion batteries (LIBs) contain a significant amount of valuable metals, representing a precious secondary resource. Solvent extraction is an effective method for recovering valuable metal ions from these batteries. This study proposes the use of a traditional extractant, Cyanex 272, combined with the ionic liquid Cyphos IL 101, to extract and recover leachate from lithium cobalt oxide (LiCoO 2 ) batteries. With an organic-to-aqueous (O/A) phase ratio of 1:1 and a temperature of 25 °C, 97.12 % of Co was extracted, only 2.37 % of Li were co-extracted. The separation factor of Co and Li ( β Co/Li ) was 1390.1. Stripping was accomplished using pure water, achieving nearly 100 % efficiency, with the extractant demonstrating excellent recyclability and stability. Due to the low viscosity of the organic phase, the extraction system exhibits excellent performance even at room temperature (25 °C), eliminating the need for additional heat input. Using Fourier-transform infrared spectroscopy (FTIR), Ultraviolet-visible spectroscopy (UV-Vis), and Nuclear Magnetic Resonance (NMR), it was confirmed that a tetrahedral Co-Cyanex 272 complex is generated during the cobalt extraction process, following a cation exchange mechanism. Concurrently, Cyphos IL 101 facilitates the extraction of Co 2 + by transferring them as [CoCl 4 ] 2− complexes from the aqueous phase into the organic phase. The novel extraction system reduces raw material costs for recycling spent lithium cobalt oxide batteries. This research highlights the feasibility of solvent extraction methods for processing spent LIBs, offering an efficient approach to recover lithium cobalt oxide batteries.