(8b) Advances in the Ultrasound-Induced Performance Improvements of Lithium-Ion Batteries and Enhancements in the Sustainable Recovery of Valuable Spent Materials

This paper will present systematic overview of the emerging advances in ultrasound-assisted technological improvements of Lithium-ion batteries (LiBs) from the perspectives of materials synthesis, process improvements and optimization; and intensification of cathode materials recovery. LiBs are playing a critical role in the current world-wide energy revolution towards diversified and sustainable developments of renewable energy sources, which include solar, wind and hydroelectric power. Recent studies have demonstrated that ultrasound-assisted technologies are green alternatives for improvements in LiBs’ process performances such as fast-charging and materials recovery and/or re-remanufacturing. Cavitation is the main mechanism for ultrasound intensification. The unique cavitation process can be in general defined as the generation, subsequent growth and collapse of the cavities releasing large magnitudes of energy over a very small location resulting in very high energy densities. Cavitation also generates local turbulence and liquid microcirculation (acoustic streaming) in the reactor enhancing the rates of transport processes. It is well known that the sudden collapse leads to localized, transient high temperatures (³5000 K) and pressures (³1000 atm), resulting in an oxidative environment due to the generation of highly reactive species including hydroxyl (^·OH), hydrogen (H^·) and hydroperoxyl (HO₂^·) radicals, and hydrogen peroxide. The mechanical effects of cavitation are mainly responsible for the intensification of physical processing applications and also chemical processing applications limited by mass transfer. Many of the observed effects of ultrasound in electrochemical processes can be explained by the enhancement of mass transport in diffusion-controlled processes such as leaching. Ultrasonic energy enhances diffusion in pores and greater porosity results in greater mass transfer enhancements; and allow anode and cathode to be freed of inhibiting product or passivating reaction films. This paper will discuss the physical and/or chemical mechanisms involved in process improvements/intensifications and the recovery and utilization of scarce mineral resources towards remanufacturing and circular economy.