Spent Lithium-ion Battery Recovery With EDTA Via Mechanochemical Activation

Among rechargeable batteries,lithium ion batteries are widely used in various portable mobile devices due to their high operating voltage,high energy density,no memory effect,light weight,and small sizes.With the end of the battery life cycle,a large number of discarded lithium-ion batteries could cause serious environmental pollution and waste of resources.Recovery of spent lithium-ion batteries not only protects the environment but also saves resources and brings huge economic effects.This paper proposes the study of leaching of valuable metals in spent lithium-ion batteries after mechanochemical activation.The battery cathode materials required for subsequent experiments were obtained after discharging and disassembling in the pretreatment stage.The cathode active material was obtained by heat treatment to remove the binder on the aluminum foil.By TG-DSC analysis,the heat treatment temperature was determined to be 400?and the heat treatment time was 30 min The treated samples were characterized by FT-IR,SEM,and XRD to find whether the binder were removed and the change in the crystal structure of the sample.In the mechanochemical activation and leaching stage,the effects of ball milling speed,ball-to-powder mass ratio,milling time,adding mass of EDTA and H₂O₂concentration on the metal leaching rate were investigated.The optimum activation and leaching conditions were as follows:ball mill speed 650 rpm,ball-to-powder mass ratio 60:1,milling time 90min,the adding mass of EDTA was 1.5 g,the concentration of H₂O₂ was 0.3 vol%.Under this condition,the leaching rate of metal Co reached at100%,and the leaching rate of metal Li reached at 98.23%.In order to find the mechanism of mechanochemical activation,the mechanical activation process was fitted by the Delogu single-phase reaction exponential equation.The reason for the increase of the ball milling speed and the ball-to-powder mass ratio to enhance the metal leaching was the enhancement of the rate constant in the activation process.Via XRD,SEM characterization,particle size analysis and the analysis of degree of disorder for activated samples revealed that one reason for the enhance of leaching rate after mechanochemical activation was that the breakage of the layer structure,the basic unit of Co-O-Co and the surface of the LiCoO₂,another was a decrease in activation energy and an increase in reaction activity after mechanochemical activation.Through economic analysis of the recycling process,it was found that this research system has certain economic advantages compared with other organic acid leaching systems.Although the recovery cost is not as good as the inorganic acid leaching system,but there was no toxic gases generating in the leaching process,and the leaching solution is non-corrosive.Therefore,this research system proposed a method for efficient and economical recovery of pent lithium ion batteries.