Effective leaching and extraction of valuable metals from electrode material of spent lithium-ion batteries using mixed organic acids leachant

The present work focuses on simultaneous recycling of Li and Co from crushed products of mixed electrode materials using mixed organic acids, in which benzenesulfonic acid and formic acid were cooperatively used as the leaching reagents. Results show that the optimal leaching efficiency of 97% Co and 99% Li were obtained under the conditions of 1.3 mol/L benzenesulfonic acid, 1.5 mol/L formic acid, a solid to liquid (S/L) ratio of 30 g/L, and 40 min reaction time at 50 °C. Meanwhile, the leaching of Li and Co fits well to logarithmic rate model with apparent activation energy of 32.7 and 47.0 kJ/mol in this given leaching system, respectively. Besides, cobalt was directly recovered from the leach liquor as pure cobalt benzene sulfonic with the recovery efficiency of 99%, and lithium can be entirely precipitated by adding phosphoric acid. Further, the reaction mechanism involves the leaching-hydrating-complexing model of LiCoO2 particles was proposed based on the dissolution behavior of metals and then verified by morphological and phase characterization (i.e. FT-IR, XRD and SEM-EDS) of the recycling product. The whole process is found to be effective and sustainable for recovery of Li, Co and graphite from mixed industrial crushing product of spent LIBs.