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 LiCoxMnyNizO2 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.