Ultrasonic renovation mechanism of spent LCO batteries: A mild condition for cathode materials recycling

Abstract

Recycling of spent lithium-ion batteries was an important step for the utilization of waste electric and electronic equipment. Commonly studies mainly focused on metal extraction while bringing the waste of chemical reagents, secondary pollution, and energy consumption. The reasons for the failure of lithium-ion batteries were the pore blocking by organics and the structural collapse in LiCoO2 crystal. Ultrasonic hydrothermal renovation was a promising method to directly renovate spent LiCoO2 crystal structure and remove the organics. It combined the advantages of ultrasonic and hydrothermal technologies which were high-efficiency and clean production. Ultrasonic cavitation generated by high-powered ultrasonic in liquid phase was a process with bubble formation and implosion. Under the effect of ultrasonic cavitation and advanced oxidation synergistically, the blocked channels and layer structure were effectively rebuilt, the organics were removed and the crystal structure of LiCoO2 was renovated. This experimental result showed that the optimal renovation condition was at the ultrasonic power of 1050 W, the reaction temperature of 90 ℃, the reaction time of 6 h, 1 mL of H2O2, and 0.5 MPa of Ar gas content. The renovated LiCoO2 exhibited good electrochemical properties, the first charge and discharge capacity of 132.1mAh•g − 1 and 131.0mAh•g − 1, and the first cycle efficiency arrived at 99.16%. Additionally, an environmentally friendly and efficient route for the recycling of spent lithium-ion batteries was developed.