H₂O-balance-regulated cation–anion competitive coordination for selective elements extraction from spent lithium-ion batteries

Key resources necessary for lithium-ion batteries (LIBs) will deplete rapidly if recycling is not considered given the significant demand for LIBs. However, the current recovery method from spent LIBs is hindered by low efficiency, high energy consumption, and severe environmental issues, which curtail the sustainability of recycling industry. Here, we propose a new strategy for selective elements extraction from LiCoO₂ based on H₂O-balance-regulated cation–anion competitive coordination. The lithium can be preferentially precipitated in deep eutectic solvents (DES) with an appropriate amount of H₂O. Such a preferential lithium behaviors contributes to the subsequent precise separation of transition metal elements by further adjusting the water content, thus enabling the recovery of all element and direct regeneration of DES for further spent LIB recycling. The developed DES-based technology can achieve the ultrahigh leaching efficiency of 99.99% for Li and Co with an acceptable recovery efficiency of Li and Co (≥91.23%) and a desirable purity of recycled Li₂C₂O₄ and CoC₂O₄·2H₂O (≥98.43%). These Li and Co performances are still maintained at this level even after three-time regeneration of DES. This methodology can also be extended to other recycling chemistries of spent LIBs and lay the theoretical foundation for the recovery of valuable metals from spent battery materials using DESs with a simple process, low energy consumption, and waste-free recycling.