Review of Ultrasound-Assisted Recycling and Utilization of Cathode Materials from Spent Lithium-Ion Batteries: State-of-the-Art and Outlook

The recycling of spent lithium-ion batteries can not only reduce the potential harm caused by solid waste piles to the local environment but also provide raw materials for manufacturing new batteries. Power ultrasound is one of the effective means to enhance the resourceful recycling of spent lithium-ion batteries, and the unique physical and chemical effects are the main mechanisms that lead to the enhancement. A large number of studies reported the recycling and utilization of cathode materials from spent lithium-ion batteries with the assistance of ultrasound. In this paper, first, we discuss the pathway of ultrasonic enhancement of the resource-based recycling of spent lithium-ion batteries regarding the introduction of ultrasonic cavitation theories; second, we systematically review the research of ultrasonic applications in the separation of metal collectors from, the recovery of, and the regeneration of cathode materials of spent lithium-ion batteries; finally, shortcomings of the ultrasound-assisted technology in industrial applications are discussed, and prospects of industrial ultrasonic applications in the resource recycling and utilization of spent lithium-ion batteries are proposed.