Green regeneration and high-value utilization technology of the electrolyte from spent lithium-ion batteries

Abstract

With the rapid growth of demand and production capacity for lithium-ion batteries (LIBs), there has been a significant and cumulative increase in the number of spent LIBs, which possess dual attributes of high risk and resource value. However, current research on their recycling and utilization primarily focuses on the cathode and anode materials, neglecting the electrolyte. This article proposes a method for recycling the spent electrolyte as a commercial electrolyte which consists of extracting it as a whole, removing impurities, and adding necessary components, such as organic solvent extraction, vacuum distillation, water leaching, molecular sieve purification, and component supplements. The results show that this method can not only remove organic phosphates that affect the electrolyte performance but also avoid the toxic gases generated by the hydrolysis of LiPF6, subsequently recovering it in the form of LiF, CaF2, Ca3(PO4)2. Furthermore, it enables the purification of organic solvents within the spent electrolyte for reuse and the preparation of a regenerated electrolyte that meets commercial requirements. The regenerated electrolyte exhibits a high ionic conductivity of 2.2 S·cm−1 at 293.15 K and an apparent activation energy of 4.73 kJ/mol, closely resembling that of a commercial electrolyte with the same composition. This research represents a significant breakthrough in electrolyte recycling, enabling the reuse of the electrolyte from spent LIBs and offering guidance for achieving a complete closed-loop recycling of LIBs.