(590c) A New Method for Lithium-Ion Battery Recycling Based on Chloroaluminate and Chloroaluminous Complexes

The sustainable electrification of transport hinges on effective recycling strategies for spent lithium-ion batteries (LIBs), given the finite nature of critical metals like lithium, cobalt, and nickel. Conventional recycling techniques, primarily pyrometallurgy and hydrometallurgy, present limitations that hinder technological advancement in this field. In response, we propose a groundbreaking recycling method that circumvents existing barriers by leveraging the facile reaction between chloroaluminate (Al-Cl complex anions) and chloroaluminous (Al-Cl complex cations) species and layered lithium transition metal oxides (LTMOs).

Our results elucidate the robust performance of AlCl₄^- in Lewis neutral chloroaluminate ionic liquid and AlCl₂⁺ in aluminum chloride solution in ethanol (AlCl₃-EtOH) in chemical delithiation of LTMOs (including lithium cobalt oxide (LiCoO₂) and lithium nickel manganese cobalt oxide (LiNi_0.6Mn_0.2Co_0.2O₂)). The strong Li-Cl attraction initiates chemical extraction Li⁺ cation from the LTMO that leads to a self-promoted reduction of transition metals to soluble lower oxidation states. This mechanism forms the basis of our innovative recycling methodology, which employs chloroaluminate and chloroaluminous complexes as highly efficient metal extraction reagents. Notably, this extraction process achieves high efficiency even under modest conditions, highlighting its potential for scalable implementation in recycling facilities.

Significantly, AlCl₃-EtOH demonstrates superior extraction efficiency under mild conditions, coupled with the recyclability of the ethanol after reaction by rotary evaporation and resulting in a blue mass which is soluble in water followed by chemical separation of highly pure cobalt hydroxide and lithium chloride. Furthermore, we showcase the applicability of our method by conducting experiments with spent real LIBs, utilizing AlCl₃-EtOH as the extraction reagent. Leading to more than 99.9% extraction efficiency for both cobalt and lithium demonstrated the viability and effectiveness of our approach in addressing the pressing need for sustainable LIB recycling. In addition to its effective extraction of valuable metals, this method facilitates the straightforward separation of graphite. Since graphite remains insoluble, it can be effortlessly filtered out prior to the chemical separation and purification of the resulting blue mass.

In conclusion, our study introduces a novel recycling paradigm that overcomes existing technological barriers, offering a sustainable solution for critical metal recovery from spent LIBs. The utilization of chloroaluminate and chloroaluminous complexes-based reagents, particularly AlCl₃-EtOH, demonstrates remarkable efficiency and practical feasibility, underscoring its potential to revolutionize the battery recycling industry and contribute to the long-term sustainability of transport electrification.