چكيده به لاتين
Abstract
Li-ion batteries have taken great attentions from various industries in recent years due to their unique properties. The increasing usage of these batteries leads to the generation of an increased amount of spent batteries, which should be recycled with regard to both environmental and economic reasons. These have encouraged many investigators towards the recovery of the contained valuable elements from spent batteries. In the present study, recycling of a LiNixMnyCozO2 type Li-ion battery was aimed with an emphasis on Li recovery. After discharging, manual dismantling and separation, the cathode of the batteries was chopped using a shredder to below 50 mm in size. The adjoined Al layer was selectively dissolved from the cathode fragments in a 2.5 M NaOH solution within 2 hours at room temperature. A response surface methodology was employed in the next step for the separation of the contained Li from the remaining solid by leaching in oxalic acid solutions. Three parameters of time (35-10 min), temperature (40-70 °C) and the concentration of oxalic acid (0.5-1.2 M) were adopted as independent variables, while dissolution efficiency of Li as well as concentration of Mn in the solution was taken as response variables. The experiments were performed and optimized based on a CCD response surface methodology. From the obtained model, an optimum condition was found to include 70 °C for temperature, 122 min for leaching time and 1.1 M for oxalic acid concentration. A verification experiment was performed, by which about 95% of Li was recovered while 98% of Mn was remained in the solid residue. At the final stage, Li was recovered from the leach solution as carbonate and phosphate precipitates by employing two different strategies.
Keywords: Recycling, Li-ion batteries, Selective dissolution, Oxalic acid, Lithium oxalate, Lithium carbonate.
