Recycling Spent Ternary Lithium-Ion Batteries into Li₄SiO₄ Sorbents and Oxygen Carriers for CO₂ Separation

Spent lithium-ion batteries (LIBs) are expected to be discarded in huge amounts due to their limited service life, causing severe environmental problems if not properly handled. It is a promising route to obtain cheap CO2 separation materials of Li-based CO2 sorbents and Ni/Mn/Co-based oxygen carriers from spent ternary LIBs, realizing a win-win outcome in terms of waste recycling and CO2 reduction. However, the migration of key impurities during the recycling of spent LIBs and the approach to synthesizing CO2 separation materials may affect their physical and chemical characteristics. Herein, the work aims to develop CO2 separation materials from spent ternary LIBs, elaborating the migration and influence of impurities, and optimizing the performance of CO2 separation materials. Results show that Ni, Co, and Mn in spent LIB cathode enter oxygen carriers with a minor amount of Li, Al, etc., while Li mainly enters Li4SiO4 sorbents with some Na and Si. After optimization, the obtained oxygen carrier of CO–OC-0.3Al possesses a stable oxygen transport capacity of 16.3% during 30 cycles of reduction and oxidation, and the sorbent of CO-Li4SiO4-0.1Na could attain an excellent CO2 capacity of 0.26 g/g within 100 cycles of adsorption and desorption. We believe that the work could lay a foundation for the efficient construction of CO2 separation materials from spent LIBs, which is of great significance for environmental protection and low-carbon energy development.