Novel Approach for in Situ Recovery of Lithium Carbonate from Spent Lithium Ion Batteries Using Vacuum Metallurgy

Lithium is a rare metal because of geographical scarcity and technical barrier. Recycling lithium resource from spent lithium ion batteries (LIBs) is significant for lithium deficiency and environmental protection. A novel approach for recycling lithium element as Li₂CO₃ from spent LIBs is proposed. First, the electrode materials preobtained by mechanical separation are pyrolyzed under enclosed vacuum condition. During this process the Li is released as Li₂CO₃ from the crystal structure of lithium transition metal oxides due to the collapse of the oxygen framework. An optimal Li recovery rate of 81.90% is achieved at 973 K for 30 min with a solid-to-liquid ratio of 25 g L^-1, and the purity rate of Li₂CO₃ is 99.7%. The collapsed mechanism is then presented to explain the release of lithium element during the vacuum pyrolysis. Three types of spent LIBs including LiMn₂O₄, LiCoO₂, and LiCo_xMn_yNi_zO₂ are processed to prove the validity of in situ recycling Li₂CO₃ from spent LIBs under enclosed vacuum condition. Finally, an economic assessment is taken to prove that this recycling process is positive.