A promising method for recovery of LiMn2O4 and graphite from waste lithium-ion batteries: Roasting enhanced flotation

In this study, a roasting enhanced flotation process was proposed to recover LiMn2O4 and grapite from waste lithium-ion batteries (LIBs). The effects of roasting temperature and time on the surface modification was investigated, and a series of analytical technologies were used to reveal process mechanism. The results indicate that LiMn2O4 can be effectively separated from graphite via flotation after the roasting. The flotation grade of LiMn2O4 was significantly increased from 63.10% to 91.36% after roasting at 550 degrees C for 2 h. The TG-DTG analysis demonstrates that the difficulty in flotation separation of LiMn2O4 from graphite is caused by the organic binder and electrolytes coating on their surfaces. The XRD, SEM, XPS, and contact angle analyses confirm that the organic films on the surfaces of those materials can be effectively removed by roasting, after which the wettability of LiMn2O4 is regained and thus the surface wettability difference between the cathode and anode materials is increased significantly. The closed-circuit flotation test indicates that a LiMn2O4 sample with high grade of 99.81% is obtained, while the recovery of LiMn2O4 is as high as 99.40%. This study provides an economical and eco-friendly way to recycling waste LIBs.